Culture

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

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

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

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

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

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

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

Piotrowska says: "It's really exciting to see how the simulations predict exactly what we see in the real Universe. Supermassive black holes - objects with masses equivalent to millions or even billions of Suns - really do have a big effect on their surroundings. These monster objects force their host galaxies into a kind of semi-retirement from star formation."

COLUMBUS, Ohio - Flavor is the name of the game for scientists who want to optimize food for consumption in ways that improve nutrition or combat obesity.

But there is more to flavor than the substances that meet the mouth. Olfaction, our sense of smell, is a major contributor to how we perceive aromas, especially those related to what we eat.

With hopes to capitalize on the smell factor in flavor development, researchers are exploring how the route an aroma takes to get to the olfactory system, through the nose or the back of the throat, influences our response to the scent in question.

In a new study, when participants were asked to match a known scent such as rose with one of four unknown scents, they did best when the aromas were introduced in the same way, either through sniffing them in a vial or drinking them in a solution - an expected result.

The scientists were surprised to find, however, that participants were also better at matching aromas when the reference scent - the one that they were going to try to find a match for - was not labeled with its familiar name. The less they knew about the reference aroma, the higher their chances of correctly identifying a match - a finding that suggests aroma detection involves learning, memory and cognitive strategy.

The team eventually wants to consider other factors that could influence the perception of aromas and flavors, such as genetics and our microbiomes, the communities of microbes living in our nasal passages and oral cavities.

"A better understanding of these mechanisms could give us another way to modulate flavors and to modulate food-related experiences," said Christopher Simons, associate professor of food science and technology at The Ohio State University and senior author of the study. "It's really hard to understand what people experience, and I don't have access to your brain to see exactly what you're perceiving. But if there are ways to influence that perception, maybe that's a way to get people to eat healthier."

The study is published in the September 2021 issue of the journal Physiology and Behavior.

Simons and colleagues were testing the theory known as the "duality of smell," which posits that how we perceive what we're smelling depends on which path it takes to get to the olfactory system.

The theory has been supported by tests of food flavors that we're used to putting in our mouths. In this study, the researchers used less familiar floral scents - which study participants drank in a solution to activate the sense of smell through the back of the throat and sniffed from a vial to activate the sense of smell through the nose.

The 34 participants would first either sniff or drink the reference scent, which was labeled with its common name - the choices were rose, lavender, honeysuckle or jasmine - its Latin name, or a generic label that gave no information. They then sampled the same unnamed four floral scents - either through the same sense-of-smell pathway or its opposite - with the goal of finding the match to the reference aroma.

When the routes of delivery differed, participants made more mistakes, meaning there was something about those delivery systems to the nose that altered their ability to recognize similar scents - further supporting the duality of smell hypothesis.

But the finding that no information was better than a clear scent name was unexpected - and also suggests that this is where cognitive activity comes into play.

"If I say 'rose,' there's information that will affect the way you process and smell those aromas. When there's no identifying information, what you have to do is profile - smell it and find something distinguishing about that particular aroma. That's much harder than knowing what you're looking for," Simons said.

"We think there's cognitive interference from the language centers that impacts how people do this matching and searching test. ... Fundamentally, the fact you have exactly the same stimulus that activates exactly the same receptors, and you can't make a match - that's fascinating."

Simons is interested in repeating this kind of test with unpleasant aromas to see if the theory holds up, and also hopes to conduct experiments that could reveal whether our genetic makeup or the array of microbes and enzymes in our noses and mouths hold secrets to why the duality of smell exists in the first place.

Champaign, IL, July 19, 2021 - For dairy cows, the transition period--the time between a cow giving birth and beginning to produce milk--brings the greatest possibility of health problems. The current widespread belief is that the effects of excess nonesterified fatty acids (NEFA) in the bloodstream and the ensuing hyperketonemia during this period, coupled with low levels of available calcium, are largely responsible for disorders such as mastitis, metritis, retained placenta, and poor fertility. Much attention has therefore been devoted to regulating NEFA and calcium levels in transition cows--yet all these efforts have not made the transition period less of a challenge to cows and, hence, to farmers, with approximately 75 percent of disease occurring during the first months postpartum. Dairy producers literally pay the price in terms of reduced milk production, costs of treatment, early culling of cows, reduced reproductive abilities, and animal welfare.

In a new review in the Journal of Dairy Science, a team from the Iowa State University Department of Animal Science, Ames, IA, USA, led by Lance H. Baumgard, PhD, Norman L. Jacobson Endowed Professor in Dairy Nutrition, critically reviews the current accepted understanding of cow health during the transition period to investigate the reasons for these persistent problems and suggests lines of inquiry and perspectives on dairy cow health that may prove more effective. Their findings call into question the methods and conclusions of a large body of previous research and how such work has been applied in the dairy industry.

"During the last 50 years, dairy scientists have increasingly viewed elevated circulating NEFA and ketones and hypocalcemia as pathological and causal toward negative outcomes," Baumgard observed.

The team found that this tenet is largely based on observational studies, epidemiology, correlations, and ex vivo immune cell function assays. "It is becoming increasingly evident that periparturient diseases and disorders cannot be explained by the severity of changes in these simple metabolites. Interpreting biomarkers as causal agents of metabolic disorders deviates from the purpose of epidemiological studies," Baumgard added. In their review of previous research, Baumgard and colleagues emphasized the fundamental scientific principle that "correlation does not equal causation."

Examining data both from dairy cows and across species, the team concluded that postcalving changes to energetic and calcium metabolism reflect normal biological processes. Healthy animals use these processes to maximize milk production. In other words, conditions that have been widely regarded as indicating poor health may in fact represent normal and even advantageous functions--and some of the ways in which the challenges of the transition period are addressed may actually make problems worse. Unhealthy cows (metritis, mastitis etc.) utilize similar processes to support an effective immune system. Thus, the unhealthy cow and high-producing healthy cow share similar metabolic profiles.

Baumgard and colleagues provide a basis for further investigating this perspective, with the suggestion that future research might focus on preventing immune system activation in cows, thereby reducing the negative effects of inflammation. Proceeding thus, with careful attention to scientific rigor, they hope to make progress in overcoming the transition cow health problems that remain key obstacles to profitable dairy farming and improving overall agricultural sustainability.

UCC-UCM, 13 July. The Giant Galapagos tortoises which live in contact with human farming and tourism activities, or in urbanised zones, have more bacterial resistance to antibiotics than those that live in more isolated ecosystems.

This is the main conclusion of the research published in Environmental Pollution on which Universidad Complutense de Madrid participated together with the Charles Darwin Foundation (FCD), the Institute for Conservation Medicine of the Saint Louis Zoo (ICM), the Centre for Animal Health Research (INIA-CISA) and Universidad Europea de Madrid.

Ainoa Nieto, the lead author, researcher at ICM/FCD and collaborator in practical teaching and doctoral student at UCM, explains the new information provided by the study: "Human activities are facilitating the dispersal of resistance into the environment, which has already been observed in other parts of the world, but which has never been demonstrated on the Galapagos Islands."

Resistance to antibiotics is one of the major threats to public health on the planet. The WHO has estimated that by 2050 it could be leading to more deaths than cancer, diabetes or traffic accidents. The detection of these bacteria in the Galapagos archipelago for the first time turn them into environmental pollutants and the tortoises into potential "sentinels or bioindicators" of the health of ecosystems.

PCR to identify genes and bacteria

To carry out the study, samples were taken from 270 tortoises in 2018 and 2019 in two locations with different characteristics in the Galapagos Islands: the island of Santa Cruz, which has the largest human population, and the remote volcano of Alcedo on the island Isabela.

The analyses of resistance were carried out in the INIA-CISA laboratory in Madrid using a new methodology that allows the detection of resistance genes without the need to cultivate the bacteria, through PCR reactions in real time. This technique helps identify the genes and also the number of bacteria with resistant genes that are present in a sample. In total, 21 genes were analysed that codify resistance for eight of the antibiotic families most commonly used in human and animal medicine.

"We don't know the real implications that this discovery could have for the health of giant tortoises, but resistance is considered environmental pollution, and the fact that species as iconic as Galapagos tortoises are entering into contact with these resistant bacteria implies that the ecosystem in which they live is being contaminated," explains Casilda Rodríguez, a researcher at the Department of Pharmacology and Toxicology at UCM.

Finally, Ainoa Nieto recalls that antibiotics can be bought in the Galapagos without a medical prescription, for both human and veterinarian use. The authorities do not restrict their use, as happens in Spain or other countries in the world.

When it comes to transitioning from carbon-based to renewable source energy systems, Americans are on board. They're less keen, however, having these new energy infrastructures--wind turbines or solar farms--built close to their homes, which creates hurdles for policymakers. That's according to a study from University of Georgia researcher Thomas Lawrence.

Lawrence and an international team conducted surveys in the United States, Germany and Ireland to assess people's attitudes about renewable energy technologies and their willingness to have the necessary infrastructures built nearby.

"People in Germany and Ireland were more open to having renewable energy technologies closer to where they lived, perhaps because they have less space than in the U.S.," said Lawrence, professor of practice in the College of Engineering. "In the U.S., I was happily surprised to see overall support for a transition of power sources--especially to solar and wind--in the electrical grid, and it was stronger than I would have guessed."

Chilly reception for fossil fuels

Respondents in each country were asked to evaluate five energy sources--wind turbines, solar power technology, and more traditional electrical power generation using biomass, coal or natural gas as the power source. They also were asked questions about what distance from their home would be acceptable for the corresponding infrastructure and these energy sources. (The surveys were conducted using the local unit system of the three countries--miles for the U.S. and kilometers for Ireland and Germany. Five kilometers is roughly 3 miles.)

In all three countries, respondents were overwhelmingly opposed to having coal-fired or natural gas power plants located close to their residences. More than 80% chose "greater than 5 km/miles" and "reject regardless of distance" as their preferred distance for coal-fired power plants (89% in Ireland, 91% in the U.S. and 81% in Germany). More than 50% chose "greater than 5 km/miles" and "reject regardless of distance" as their preferred distance for natural gas power plants (80% in Ireland, 77% in the U.S. and 51% in Germany). They were generally more in favor of having renewable energy technologies located closer to their homes.

Respondents in Ireland and the U.S. were less willing to accept biomass power technology in their immediate vicinity, with more than 70% choosing "greater than 5 km/miles" or "reject regardless of distance" options. German respondents were somewhat more accepting, with 55% accepting biomass at distances less than 5 km/miles from their homes. According to Lawrence, the U.S. result may be because people here do not understand "biomass power," which is in essence burning biomass such as wood scraps to power a more traditional electrical generation facility.

A warmer response for renewable energy

Americans were more open to having renewable energy technologies located near their homes, compared to traditional energy technologies, with 24% agreeing to solar infrastructure and 17% agreeing to wind turbines located 0-1 km/miles from their residences. Irish respondents had higher acceptance rates for solar, with 42% agreeing to solar infrastructure 0-1 km/miles from their homes, and slightly lower rates for wind turbines, with 13% agreeing to wind turbines at the same distance. German respondents were far more open to these energy sources, with 74% agreeing to solar and 33% agreeing to wind turbines located 0-1 km/miles from their homes.

Greater acceptance of renewable energy sources in Germany is not a surprise, according to Lawrence.

"Germany has been leading the charge in transitioning away from carbon-based energy sources," he said. "Over 30% of their power right now is through wind or solar. People there are used to seeing wind farms and solar panels on rooftops."

The study, published in The Energy Journal, also examined preferences related to different national energy policy objectives: economic viability, environmental sustainability, reliability of energy supply and social acceptance.

Results revealed that social acceptance is a more significant energy policy concern for Ireland compared to either Germany or the U.S. Respondents in Ireland rank social acceptance as more important than environmental sustainability or reliability of supply. They also place more importance on those three variables compared to economic viability.

In contrast, German respondents rank all the national policy objectives examined as more important than social acceptance, though similarly, they place greater importance on environmental sustainability and reliability of supply than economic viability. Respondents from the U.S. place much lower importance on social acceptance as a national policy objective, compared to the other three policy objectives.

"Respondents in all three countries were generally more in favor of having renewable energy technologies close to their homes--unlike conventional energy technologies like coal and natural gas--but 'close to my home' was different in the U.S. than Europe," Lawrence said. "Five miles was the cutoff, at least in the U.S. Once you get beyond that point, it's out of sight, out of mind. People in Germany and Ireland often don't have the luxury of five miles."

A serendipitous flythrough of the tail of a disintegrated comet has offered scientists a unique opportunity to study these remarkable structures, in new research presented today at the National Astronomy Meeting 2021.

Comet ATLAS fragmented just before its closest approach to the Sun last year, leaving its former tail trailing through space in the form of wispy clouds of dust and charged particles. The disintegration was observed by the Hubble Space Telescope in April 2020, but more recently the ESA spacecraft Solar Orbiter has flown close to the tail remnants in the course of its ongoing mission.

This lucky encounter has presented researchers with a unique opportunity to investigate the structure of an isolated cometary tail. Using combined measurements from all of Solar Orbiter's in-situ instruments, the scientists have reconstructed the encounter with ATLAS's tail. The resulting model indicates that the ambient interplanetary magnetic field carried by the solar wind 'drapes' around the comet, and surrounds a central tail region with a weaker magnetic field.

Comets are typically characterized by two separate tails; one is the well-known bright and curved dust tail, the other - typically fainter - is the ion tail. The ion tail originates from the interaction between the cometary gas and the surrounding solar wind, the hot gas of charged particles that constantly blows from the Sun and permeates the whole Solar System.

When the solar wind interacts with a solid obstacle, like a comet, its magnetic field is thought to bend and 'drape' around it. The simultaneous presence of magnetic field draping and cometary ions released by the melting of the icy nucleus then produces the characteristic second ion tail, which can extend for large distances downstream from the comet's nucleus.

Lorenzo Matteini, a solar physicist at Imperial College London and leader of the work, says: "This is quite a unique event, and an exciting opportunity for us to study the makeup and structure of comet tails in unprecedented detail. Hopefully with the Parker Solar Probe and Solar Orbiter now orbiting the Sun closer than ever before, these events may become much more common in future!"

This is the first comet tail detection occurring so close to the Sun - well inside the orbit of Venus. It is also one of the very few cases where scientists have been able to make direct measurements from a fragmented comet. Data from this encounter is expected to contribute greatly to our understanding of the interaction of comets with the solar wind and the structure and formation of their ion tails.

RESEARCH TRIANGLE PARK, N.C. -- Army-funded research identified a new material that may lead to lightweight armor, protective coatings, blast shields and other impact-resistant structures.

Researchers at the U.S. Army's Institute for Soldier Nanotechnologies at the Massachusetts Institute of Technology, Caltech and ETH Zürich found that materials formed from precisely patterned nanoscale trusses are tougher than Kevlar and steel.

In experiments, the ultralight structures, called nanoarchitectured materials, absorbed the impact of microscopic projectiles accelerated to supersonic speeds.

"Increasing protection while simultaneously decreasing the weight that soldiers carry is an overreaching theme in our research," said Dr. James Burgess, ISN program manager for the U.S. Army Combat Capabilities Development Command, known as DEVCOM, Army Research Laboratory. "This project is a really good example of such efforts where projectile energy absorption is nanostructured mechanism based."

The research, published in Nature Materials, found that the material prevented the projectiles from tearing through it.

"The same amount of mass of our material would be much more efficient at stopping a projectile than the same amount of mass of Kevlar," said Dr. Carlos Portela, assistant professor of mechanical engineering at MIT, the study's lead author.

The researchers calculate that the new material absorbs impacts more efficiently than steel, Kevlar, aluminum and other impact-resistant materials of comparable weight.

"The knowledge from this work...could provide design principles for ultra-lightweight impact resistant materials [for use in] efficient armor materials, protective coatings, and blast-resistant shields desirable in defense and space applications," said co-author Dr. Julia R. Greer, a professor of materials science, mechanics, and medical engineering at Caltech, whose lab fabricated the material.

Nanoarchitected materials are known to feature impressive properties like exceptional lightness and resilience; however, until now, the potential for additional applications has largely been untested.

"We only know about its response in a slow-deformation regime, whereas a lot of their practical use is hypothesized to be in real-world applications where nothing deforms slowly," Portela said.

To help fill this vital knowledge gap, the research team set out to study nanoarchitected materials undergoing fast deformation, such as that caused by high-velocity impacts. At Caltech, researchers first fabricated a repeating pattern known as a tetrakaidecahedron--a lattice configuration composed of microscopic struts--using two-photo lithography, a technique that uses a high-powered laser to solidify microscopic structures in photosensitive resin.

To test the tetrakaidecahedron's resilience to extreme, rapid deformation, the team performed experiments at MIT using the ISN-developed laser-induced particle impact array. This device aims an ultrafast laser through a glass slide.. As the laser passes through the slide, it generates a plasma, an immediate expansion of gas that launches the particles toward the target.

By adjusting the laser's power to control the speed of the microparticle projectiles, the researchers tested microparticle velocities within the supersonic range.

"Some experiments achieved twice the speed of sound, easily," Portela said.

Using a high-speed camera, the researchers captured videos of the microparticles impacting the nanoarchitected material. They had fabricated material of two different densities. A comparison of the two materials' impact response, found the denser one to be more resilient, and microparticles tended to embed in the material rather than tear through it.

To get a closer look, the researchers carefully sliced through the embedded microparticles and nanarchitectured target. They found that the struts below the embedded particle had crumpled and compacted in response to the impact, but the surrounding struts remained intact.

"We show the material can absorb a lot of energy because of this shock compaction mechanism of struts at the nanoscale, versus something that's fully dense and monolithic, not nanoarchitected," Portela said.

Going forward, Portela plans to explore various nanostructured configurations other than carbon, and ways to scale up the production of these nanostructures, all with the goal of designing tougher, lighter materials.

"Nanoarchitected materials truly are promising as impact-mitigating materials," Portela said. "There's a lot we don't know about them yet, and we're starting this path to answering these questions and opening the door to their widespread applications."

It's no secret that studies show that sexually diverse youth - in particular, lesbian, gay and bisexual (LGB) youth - use more cannabis and experience more mental health challenges than their heterosexual peers.

But what about the changes that occur in the rates of cannabis use: do they precede those related to mental health or is it the other way around? A new study from Université de Montréal offers some answers.

In the Journal of Abnormal Psychology, Kira London-Nadeau, a doctoral student and CIHR Vanier Scholar in the Department of Psychology at UdeM and the CHU Sainte-Justine Research Centre, provides an update.

In her study, conducted under the direction of Professor Natalie Castellanos-Ryan and with the support of Professors Jean Séguin and Sophie Parent, London-Nadeau analyzed data collected from 1,548 adolescent boys and girls - including 128 LGB adolescents - as part of the Longitudinal Study of Child Development in Quebec supported by CIHR and the Institut de la Statistique du Québec.

Participants were followed from the age of five months and the study was based on their responses to questionnaires collected at ages 13, 15 and 17. Although there was an association between depressive symptoms at age 15 and increased cannabis use at age 17 in the general sample, the association was five times stronger among LGB youth.

According to London-Nadeau, this relationship may signal a practice of LGB youth self-medicating with cannabis to cope with depressive symptoms. The use of cannabis for these purposes could also indicate that other sources of support for depressive symptoms are lacking or inadequate for the realities of LGB youth.

Unexpectedly, the study also found that anxiety symptoms among LGBs at age 15 predicted reduced cannabis use at age 17. This finding thus seems to run counter to the finding of an association between depression and cannabis use in the LGB group.

"The difference between the depression-cannabis relationship and the anxiety-cannabis relationship could indicate different realities that LGB youth would experience, particularly with respect to their public display of their minority sexual orientation," said London-Nadeau.

Thus, the researcher believes that social factors related to the experience of a minority sexual orientation would play an important role in both cannabis use and mental health challenges and the relationship between the two among adolescents.

In this regard, London-Nadeau emphasizes the need for youth services, particularly mental health services, to be better equipped to understand the issues specific to sexual diversity communities.

"As a teenager, you're constantly trying to figure out your identity as a person, which in itself is pretty difficult," said the young researcher, who identifies herself as gay. "When you add the discovery of a minority sexual orientation to that identity development, things get even more complicated."

"Now it's a matter of digging deeper into the why of these associations and making sure to include other communities that may be having similar experiences, including trans and non-binary teens, as well as sexually and gender diverse young adults," she continued.

"These results will be crucial for these communities, as they will allow us to better target their needs to ultimately achieve a more equitable level of parity in their health."

GAINESVILLE, Fla. --- Plants are DNA hoarders. Adhering to the maxim of never throwing anything out that might be useful later, they often duplicate their entire genome and hang on to the added genetic baggage. All those extra genes are then free to mutate and produce new physical traits, hastening the tempo of evolution.

A new study shows that such duplication events have been vitally important throughout the evolutionary history of gymnosperms, a diverse group of seed plants that includes pines, cypresses, sequoias, ginkgos and cycads. Published today in Nature Plants, the research indicates that a genome duplication in the ancestor of modern gymnosperms might have directly contributed to the origin of the group over 350 million years ago. Subsequent duplications provided raw material for the evolution of innovative traits that enabled these plants to persist in dramatically changing ecosystems, laying the foundation for a recent resurgence over the last 20 million years.

"This event at the start of their evolution created an opportunity for genes to evolve and create totally new functions that potentially helped gymnosperms transition to new habitats and aided in their ecological ascendance," said Gregory Stull, a recent doctoral graduate of the Florida Museum of Natural History and lead author of the study.

Taking a closer look at gymnosperms

While having more than two sets of chromosomes - a phenomenon called polyploidy - is rare in animals, in plants it is commonplace. Most of the fruits and vegetables we eat, for example, are polyploids, often involving hybridization between two closely related species. Many plants, including wheat, peanuts, coffee, oats and strawberries, benefit from having multiple divergent copies of DNA, which can lead to faster growth rates and an increase in size and weight.

Until now, however, it's been unclear how polyploidy may have influenced the evolution of gymnosperms. Although they have some of the largest genomes in the plant kingdom, they have low chromosome numbers, which for decades prompted scientists to assume that polyploidy wasn't as prevalent or important in these plants.

Gymnosperm genetics are also complex. Their large genomes make them challenging to study, and much of their DNA consists of repeating sequences that don't code for anything.

"What makes gymnosperm genomes complex is they seem to have a proclivity for accumulating lots of repetitive elements," said study co-author Douglas Soltis, Florida Museum curator and University of Florida distinguished professor. "Things like ginkgos, cycads, pines and other conifers are loaded with all this repetitive stuff that has nothing to do with genome duplication."

However, a recent collaborative effort among plant biologists, including Soltis, to obtain massive numbers of genetic sequences from more than 1,000 plants has opened new doors for scientists attempting to piece together the long history of land plant evolution. Stull, now a postdoctoral researcher at the Chinese Academy of Sciences' Kunming Institute of Botany, and his colleagues used a combination of these data and newly generated sequences to give gymnosperms another look.

Genome duplication gave rise to gymnosperms

By comparing the DNA of living gymnosperms, the researchers were able to peer back in time, uncovering evidence for multiple ancient genome duplication events that coincided with the origin of major groups.

Gymnosperms have undergone significant extinctions throughout their long history, making it difficult to decipher the exact nature of their relationships. But the genomes of all living gymnosperms share the signature of an ancient duplication in the distant past, more than 350 million years ago. More than 100 million years later, another duplication gave rise to the pine family, while a third led to the origin of podocarps, a group containing mostly trees and shrubs that today are primarily restricted to the Southern Hemisphere.

In each case, analyses revealed a strong link between duplicated DNA and the evolution of unique traits. While future studies are needed to determine exactly which traits arose due to polyploidy, possible candidates include the strange egglike roots of cycads that harbor nitrogen-fixing bacteria and the diverse cone structures found across modern conifers. Podocarp cones, for example, are highly modified and look deceptively like fruit, said Stull: "Their cones are very fleshy, have various colors and are dispersed by different animals."

Competition and climate change led to extinction and diversification

Stull and his colleagues also wanted to know whether genome duplications influenced the rate at which new gymnosperm species evolved through time. But instead of a clear-cut pattern, they found a complex interplay of extinction and diversification amidst a backdrop of a significantly changing global climates.

Today, there are about 1,000 gymnosperm species, which may not seem like many when compared with the 300,000 or so species of flowering plants. But in their heyday, gymnosperms were much more diverse.

Gymnosperms were still thriving prior to the asteroid extinction event 66 million years ago, best known for the demise of dinosaurs. But the dramatic ecological changes brought about by the impact tipped the scales: After the dinosaurs disappeared, flowering plants quickly began outcompeting gymnosperm lineages, which suffered major bouts of extinction as a result. Some groups were snuffed out entirely, while others barely managed to survive to the present. The once flourishing ginkgo family, for example, is today represented by a single living species.

But the results from this study indicate that at least some gymnosperm groups made a comeback starting around 20 million years ago, coinciding with Earth's transition to a cooler, drier climate.

"We see points in history where gymnosperms didn't just continue to decline, but they actually diversified in species numbers as well, which makes for a more dynamic picture of their evolutionary history," said co-author Pamela Soltis, Florida Museum curator and UF distinguished professor.

While some gymnosperms failed to cope with the dual specter of climate change and competition, others had an advantage in certain habitats due to the very traits that caused them to lose out in their ancient rivalry with flowering plants. Groups such as pines, spruces, firs and junipers got fresh starts.

"In some respects, gymnosperms maybe aren't that flexible," Pamela Soltis said. "They kind of have to 'wait around' until climate is more favorable in order for them to diversify."

In some environments, gymnosperms adapted to live at the extremes. In pine forests of southeastern North America, longleaf pines are adapted to frequent fires that incinerate their competition, and conifers dominate the boreal forests of the far north. But take away the fire or the cold, and flowering plants quickly start to encroach.

While gymnosperms are still in the process of diversifying, they've been interrupted by human-made changes to the environment. Currently, more than 40% of gymnosperms are threatened by extinction due to the cumulative pressures of climate change and habitat loss. Future studies clarifying how their underlying genetics enabled them to persist to the present may give scientists a better framework for ensuring they survive well into the future.

"Even though some conifer and cycad groups have diversified considerably over the past 20 million years, many species have highly restricted distributions and are at risk of extinction," Stull said. "Efforts to reduce habitat loss are likely essential for conserving the many species currently threatened by extinction."

Errors in the metabolic processes of mitochondria are responsible for a variety of diseases such as Parkinson's and Alzheimer's. Scientists needed to find out just how the necessary building blocks are imported into the complex biochemical apparatus of these cell areas. The TOM complex (translocase of the outer mitochondrial membrane) is considered the gateway to the mitochondrion, the proverbial powerhouse of the cell. The working group headed by Professor Chris Meisinger at the Institute of Biochemistry and Molecular Biology at the University of Freiburg has now demonstrated - in human cells - how signaling molecules control this gate. A signaling protein called DYRK1A modifies the molecular machinery of TOM and makes it more permeable for enzymes that are important for the cell metabolism. The group has thus discovered the first signaling protein that directly influences this import process in humans. Their work has been published in the journal Nature Communications.

Developmental disorders in a new light

In neurodevelopmental disorders such as autism, microcephaly and Down's syndrome, DYRK1A is defective. "The connection with mitochondria is new. These results allow us to better understand these disorders and develop treatment strategies," says Dr. Adinarayana Marada, a member of Meisinger's team.

"For a long time, researchers thought that the TOM complex was a rigid structure in the mitochondrial membrane whose doors were always open," Meisinger explains. His team recently demonstrated signaling mechanisms in baker's yeast that alter the subunits of the TOM complex depending on the metabolic state of the cell, or in response to sudden stress. In this way, the cell can specifically control the influx of precursor proteins for building elements of the metabolism, and it can adapt the function of the mitochondria to an altered cellular state. Whether such mechanisms also exist in humans was previously unknown.

DYRK1A acts upon the TOM complex

The first authors of the study, Dr. Corvin Walter and Dr. Adinarayana Marada of Meisinger's research group, developed a systematic approach to track down signaling mechanisms such as those triggered by protein kinases, in humans. Over several years, they tested candidates using cell biological and bioinformatic methods and found what they were looking for - DYRK1A, one such protein kinase, acts on the TOM complex. "With this, we actually found the needle in the haystack," says Walter.

Three decades ago, child development researchers found that low-income children heard tens of millions fewer words in their homes than their more affluent peers by the time they reached kindergarten. This "word gap" was and continues to be linked to a socioeconomic disparity in academic achievement.

While parenting deficiencies have long been blamed for the word gap, new research from the University of California, Berkeley, implicates the economic context in which parenting takes place -- in other words, the wealth gap.

The findings, published this month in the journal Developmental Science, provide the first evidence that parents may talk less to their kids when experiencing financial scarcity.

"We were interested in what happens when parents think about or experience financial scarcity and found evidence that such strain could suppress their speech to their children," said study senior author Mahesh Srinivasan, a professor of psychology at UC Berkeley.

"Our results suggest that parenting training may not be sufficient to close the academic achievement gap without addressing the broader issue of income inequality," Srinivasan added.

The study's preliminary results lend credence to the developmental and educational benefits of such poverty-cutting government programs as the federal American Rescue Plan's Child Tax Credit and other supplemental cash payouts for needy families.

"Existing interventions toward eliminating the word gap have often focused on improving parenting skills," Srinivasan said. "But our findings suggest that relieving parents of their financial burdens, such as through direct cash transfers, could also substantially change the ways they engage with their kids."

In the first experiment, researchers sought to observe how parents would interact with their children (in this case, 3-year-olds) after the parents were asked to describe times in which they had recently experienced scarcity. A control group of parents were instead asked to describe other recent activities.

Of the 84 parents in the study, those in the experimental group who described their experiences of financial scarcity spoke less to their 3-year-olds during laboratory observations than parents who reflected on other forms of scarcity (like not having enough fruit), or parents who had not been asked to recollect experiences of resource insecurity.

The second experiment used existing data collected via LENA technology, tiny "talk pedometer" devices worn by children that record their conversations and count the words they hear and say.

As the researchers predicted, analyses revealed that parents engaged in fewer conversational turns with their children at the month's end, a time that typically coincides with money being tight as parents await paychecks or other sources of income.

"Because we had recordings from the same parents at different times of the month, we could essentially use parents as their own controls," said study lead author Monica Ellwood-Lowe, a Ph.D. student in psychology at UC Berkeley.

"This allowed us to really pinpoint differences in their speech patterns when they were more or less likely to be experiencing financial strain, independent of any of their own personal characteristics."

The term "word gap" was coined in the early 1990s when University of Kansas researchers Betty Hart and Todd Risley tracked verbal interactions in the homes of 42 families to study early language development in the children's first three years.

Each day, the researchers recorded an hour of conversation in each household, then counted all the words the children heard during those recording times.

The results were detailed in their 1995 book, Meaningful Differences in the Everyday Experience of Young American Children, and in a 2003 follow-up article, "The Early Catastrophe: The 30 Million Word Gap by Age 3."

While some have questioned Hart and Risley's methodology, their basic finding has been replicated many times, prompting calls for approaches to narrow the disparity. Enter Srinivasan and his research team:

"It struck us that what was missing from the conversation about the word gap was the possibility that poverty, and the many difficult experiences associated with it, could itself affect parents' speech," Srinivasan said.

Preliminary findings support the researchers' hypothesis but also call for a deeper dive into the relationship between money worries and parents' verbal engagement with their children, he said.

"This research doesn't mean that children whose parents are struggling financially are doomed to have smaller vocabularies," Ellwood-Lowe said. "The takeaway here is really just the importance of making sure parents have the resources they need to parent."

"If you are worried about putting food on the table tonight, or scraping together money for that medical bill, or figuring out where to enroll your child in school now that you have been evicted from your neighborhood, you may be less likely to narrate the color of the sky to your child as you ride together on the bus," the study concludes.

The link between on-road traffic and air pollution is well-known, as are the negative health impacts of pollution exposure. However, the many factors that may influence commuters' exposure to pollutants - such as frequency, time, and duration of commute - and the overall impact of commuting remains a matter of on-going scientific discovery.

Dr. Jenna Krall, assistant professor at the George Mason University College of Health and Human Services, is using statistical methods to better understand exposure to air pollution. Krall studies how commuting patterns impact exposure to fine particulate matter (PM2.5) from various traffic-related sources such as tailpipe emissions, road salts, and brake wear.

New research from Krall and colleagues published in Environmental Research examines commuter characteristics to better understand how factors such as departure time, commute length, and number of trips are associated with exposure to PM2.5. Building on a study of 46 women's exposure to PM2.5 using personal air pollution monitors, the new research clustered commuters to determine whether these clusters were associated with traffic pollution exposures. The new study reveals that commuters that travel to work during rush hour have higher overall exposure to traffic-related air pollution compared to sporadic commuters, though the difference was not statistically significant.

As COVID-19 infection rates decline in most areas of the country and employers weigh whether to continue work-from-home policies, studies such as this provide important insight into the role that daily commutes can play in personal air pollution exposure and the public's health.

"This is one of the first studies to utilize in-vehicle monitoring, specifically on-board diagnostics data loggers, to understand real-world commuting behaviors for environmental health," said Krall, "Linking these data with personal air pollution monitoring allowed us to better understand how commuter characteristics are associated with sources of air pollution exposures."

"The current research cannot tell us whether modifying commutes, for example by avoiding highways or commuting outside of rush hour, will lower traffic pollution exposures for commuters. More research is needed to determine what changes would be effective to lower exposures," says Krall.

Krall's on-going research seeks to distinguish between similar sources of traffic pollution, such as pollution generated by brake wear or from tailpipe emissions, and to develop statistical methods to better estimate exposure to pollution sources.

Study participants included 46 women commuters in northern Virginia who were exposed to pollution generated by mobile vehicles, road salts, and other sources throughout a 48-hour period.

Although people in early 2020 hoarded toilet paper, washed their hands incessantly, and wouldn't leave home, 11 months later the public pushed the envelope on COVID-19 safety precautions and ignored warnings as time went on, a new University of California, Davis, study suggests.

Researchers in the Department of Communication examined people's reactions and expressions of anxiety about news articles on Twitter. Additionally, they investigated reactions to fear-inducing health news over time, despite the steadily rising COVID-19 death toll, said Hannah Stevens, a doctoral student in communication and lead author of the paper.

The paper, "Desensitization to Fear-Inducting COVID-19 Health News on Twitter: Observational Study," was published in the Journal of Medical Internet Research Infodemiology on July 16. The researchers examined how COVID-19 news articles shared to Twitter were first met with anxiety-ridden tweets early in the pandemic, during a coinciding spike in instances of panic-buying, extreme social distancing and quarantine measures. Despite the increased death toll, those behaviors then gave way over time to less concerned responses to COVID-19 news, along with increases in societal risk-taking during that time period.

"COVID-19 has made an indelible mark on history, and now it's time to consider what went wrong so we can do better in communicating more effectively during future health crises, and even now, as the delta variant becomes more widespread," said Stevens. "First and foremost, we need to understand how and why scary health news lost impact over time, despite the rapidly increasing death toll."

The authors set out to test the hypothesis that early fear-based health messages in news reports significantly motivated individuals to take actions to control the threat, yet over-exposure to the same messages desensitized people -- or made them less likely to feel anxious over time.

During a period of 11 months, the team used a computerized methodology to analyze linguistic anxiety levels in hundreds of COVID-19 news articles on Twitter, along with the anxiety levels in corresponding user tweets. They then correlated the findings with the COVID-19 death toll in the United States.

"Our study shows a need to delve deeper into how to re-sensitize the public and motivate them to take action in the face of an ongoing emergency. Testing the effectiveness of various health-risk communication strategies could quite possibly mean the difference between life and death in the future," Stevens said.

"If another health crisis occurred today, or COVID-19 takes another turn for the worse, it is essential for public health officials to consider that they are communicating to a desensitized public. I hope that this paper can be an impetus to get that discussion started."

Tokyo, Japan - Designing materials that have the necessary properties to fulfill specific functions is a challenge faced by researchers working in areas from catalysis to solar cells. To speed up development processes, modeling approaches can be used to predict information to guide refinements. Researchers from The University of Tokyo Institute of Industrial Science have developed a machine learning model to determine characteristics of bonded and adsorbed materials based on parameters of the individual components. Their findings are published in Applied Physics Express.

Factors such as the length and strength of bonds in materials play crucial roles in determining the structures and properties we experience on the macroscopic scale. The ability to easily predict these characteristics is therefore valuable when designing new materials.

The density of states (DOS) is a parameter that can be calculated for individual atoms, molecules, and materials. Put simply, it describes the options available to the electrons that arrange themselves in a material. A modeling approach that can take this information for selected components and produce useful data for the desired product--with no need to make and analyze the material--is an attractive tool.

The researchers used a machine learning approach--where the model refines its response without human intervention--to predict four different properties of products from the DOS information of the individual components. Although the DOS has been used as a descriptor to establish single parameters before, this is the first time multiple different properties have been predicted.

"We were able to quantitatively predict the binding energy, bond length, number of covalent electrons, and the Fermi energy after bonding for three different general types of system," explains study first author Eiki Suzuki. "And our predictions were very accurate across all of the properties."

Because the calculation of DOS of an isolated state is less complex than for bonded systems, the analysis is relatively efficient. In addition, the neural network model used performed well even when only 20% of the dataset was used for training.

"A significant advantage of our model is that it is general and can be applied to a wide variety of systems," study corresponding author Teruyasu Mizoguchi explains. "We believe that our findings could make a significant contribution to numerous development processes, for example in catalysis, and could be particularly useful in newer research areas such as nano clusters and nanowires."

Testing of an entire Italian town shows antibody levels remain high nine months after SARS-CoV-2 infection, whether symptomatic or asymptomatic.

Researchers from the University of Padua and Imperial College London tested more than 85 percent of the 3,000 residents of Vo', Italy, in February/March 2020 for infection with SARS-CoV-2, the virus that causes COVID-19, and tested them again in May and November 2020 for antibodies against the virus.

The team found that 98.8 percent of people infected in February/March showed detectable levels of antibodies in November, and there was no difference between people who had suffered symptoms of COVID-19 and those that had been symptom-free. The results are published today in Nature Communications.

Antibody levels were tracked using three 'assays' - tests that detect different types of antibodies that respond to different parts of the virus. The results showed that while all antibody types showed some decline between May and November, the rate of decay was different depending on the assay.

The team also found cases of antibody levels increasing in some people, suggesting potential re-infections with the virus, providing a boost to the immune system.

Lead author Dr Ilaria Dorigatti, from the MRC Centre for Global Infectious Disease Analysis and the Abdul Latif Jameel Institute for Disease and Emergency Analytics (J-IDEA) at Imperial, said: "We found no evidence that antibody levels between symptomatic and asymptomatic infections differ significantly, suggesting that the strength of the immune response does not depend on the symptoms and the severity of the infection.

"However, our study does shows that antibody levels vary, sometimes markedly, depending on the test used. This means that caution is needed when comparing estimates of infection levels in a population obtained in different parts of the world with different tests and at different times."

Professor Enrico Lavezzo, from the University of Padua, said: "The May testing demonstrated that 3.5 percent of the Vo' population had been exposed to the virus, even though not all of these subjects were aware of their exposure given the large fraction of asymptomatic infections.

"However, at the follow-up, which was performed roughly nine months after the outbreak, we found that antibodies were less abundant, so we need to continue to monitor antibody persistence for longer time spans."

The team also investigated the infection status of household members, to estimate how likely an infected member is to pass on the infection within the household. Their modelling suggests that there was a probability of about 1 in 4 that a person infected with SARS-CoV-2 passes the infection to a family member and that most transmission (79 percent) is caused by 20 percent of infections.

This finding confirms that there are large differences in the number of secondary cases generated by infected people, with the majority of infections generating no further infections and a minority of the infections generating a large number of infections.

The large differences in how one infected person may infect others in the population suggests that behavioural factors are key for epidemic control, and physical distancing, as well as limiting the number of contacts and mask wearing, continue to be important to reduce the risk of transmitting the disease, even in highly vaccinated populations.

The team's dataset, which includes the results of the two mass PCR testing campaigns conducted in February and March and the antibody survey conducted in May and then again in November, also allowed them to tease apart the impact of various control measures.

They showed that, in the absence of case isolation and short lockdowns, manual contact tracing alone would not have been enough to suppress the epidemic.

Project lead Professor Andrea Crisanti, from the Department of Life Sciences at Imperial and the Department of Molecular Medicine at the University of Padua, said: "Our study also shows that manual contact tracing - the search for positive individuals on the basis of known and declared contacts - would have had a limited impact on the containment of the epidemic, had it not been accompanied by a mass screening."

Dr Dorigatti added: "It is clear that the epidemic is not over, neither in Italy nor abroad. Moving forward, I think that it is of fundamental importance to continue administering first and second vaccine doses as well as to strengthen surveillance including contact tracing. Encouraging caution and limiting the risk of acquiring SARS-CoV-2 will continue to be essential."