Brain

MoS2 thin films of superposed alternating layers of molybdenum and sulfur atoms form a two-dimensional semiconducting surface. However, even a surprisingly low-intensity blue light pulse is enough to alter the properties of the surface and make it metallic. This has now been demonstrated by a team at BESSY II.

The exciting thing is that the MoS2 layers in this metallic phase are also particularly active catalytically. They can then be employed, for example, as catalysts for splitting of water into hydrogen and oxygen. As inexpensive catalysts, they could facilitate the production of hydrogen - an energy carrier whose combustion produces no CO2, only water.

Physicist Dr. Nomi Sorgenfrei and her team have constructed a new instrument at BESSY II to precisely measure the changes in samples using temporally-resolved electron spectroscopy for chemical analysis (trESCA) when irradiating the samples with low-intensity, ultra-short light pulses. These light pulses are generated at BESSY II using femtosecond time-slicing (femtoslicing) and are therefore both low intensity and extremely short duration. The new instrument, named SurfaceDynamics@FemtoSpeX, can also rapidly obtain meaningful measurements of electron energies, surface chemistry, and transient alterations using these low-intensity light pulses.

Analysis of the empirical data showed that the light pulse leads to a transient accumulation of charge at the surface of the sample, triggering the phase transition at the surface from a semiconducting to a metallic state.

"This phenomenon should also occur in other representatives of this class of materials, the p-doped semiconducting dichalcogenides, so it opens up possibilities of influencing functionality and catalytic activity in a deliberate way", Sorgenfrei explains.

PULLMAN, Wash. - The ability to identify misinformation only benefits people who have some skepticism toward social media, according to a new study from Washington State University.

Researchers found that people with a strong trust in information found on social media sites were more likely to believe conspiracies, which falsely explain significant events as part of a secret evil plot, even if they could identify other types of misinformation. The study, published in the journal Public Understanding of Science on March 5, showed this held true for beliefs in older conspiracy theories as well as newer ones around COVID-19.

"There was some good and bad news in this study," said Porismita Borah, an associate professor in WSU's Edward R. Murrow College of Communication and a corresponding author on the study. "The good news is that you are less susceptible to conspiracy theories if you have some media literacy skills, one of which is being able to identify misinformation. But if you blindly trust the information you find on social media, those skills might not be able to help."

Identifying misinformation is just one part of media literacy, Borah pointed out, and people may need a deeper education around social media to avoid falling for conspiracy theories.

For the study, the researchers surveyed 760 people recruited via Amazon's Mechanical Turk crowdsourcing website. The participants were roughly split between male and female as well as Democrat and Republican. The majority, 63.1%, used Facebook and 47.3% used Twitter daily. They answered a range of questions related to the level of their social media news use and trust as well as ability to identify misinformation.

The participants were also asked to rate the truth of several COVID-19 conspiracy theories, such as the belief that the virus was a weapon of biological warfare developed by foreign countries. They also were presented with older conspiracies to rate, such as that the moon landing was a hoax and that Princess Diana was killed by a British intelligence agency.

The researchers found that a greater ability to identify misinformation lowered beliefs in all conspiracy theories--except for those who had high levels of trust in social media information. This is particularly problematic because other research has shown that once a conspiracy belief takes hold, it is very hard to convince the believer that it is false.

"The patterns around trust is one of the most important findings from our study," said Borah. "We need to go deeper into what this trust means."

Borah and her co-authors, recent WSU Ph.D. Xizhu Xiao and current doctoral student Yan Su, suggest that political ideology may play a role in this trust--that people want to believe the words of political figures they admire, whether what they say is actually true or not. Borah said more research is needed to understand why conspiracy theories appeal to people and how best to combat them as there can be serious consequences.

"There are different levels of danger with these theories, but one of the prominent conspiracy beliefs about COVID-19 is that it isn't true, that the virus is a hoax and that can be really dangerous: you're putting yourself, your family members and your community at risk," said Borah.

The researchers advocate for making media literacy part of the educational system and starting it well before college. They argue that such education should include a better understanding of how information can be manipulated as well as social media environments, news production and dissemination.

"There's a long list of tasks to do to keep ourselves well informed," Borah said. "I think there is hope with media literacy and a better understanding of the information environment, but it is a complicated process."

Oxidative dispersion has been widely used in the regeneration of sintered metal catalysts as well as the fabrication of single-atom catalysts.

The consensus on the oxidative dispersion process includes the formation of mobile metal oxide species from large metal particles and the capture of these species on a support surface. Nevertheless, the mechanism of oxidation-induced dispersion has yet to be confirmed via in situ electron microscopic and/or spectroscopic characterizations.

Recently, a research team led by Prof. FU Qiang and Prof. BAO Xinhe from the Dalian Institute of Chemical Physics (DICP) of the Chinese Academy of Sciences (CAS), in collaboration with Prof. YANG Bing from DICP and Prof. GAO Yi from the Shanghai Institute of Applied Physics of CAS, reported the oxygen adsorption-induced dispersion of metallic Ag nanoclusters in a typical oxidative atmosphere.

The results were published in Nature Communications on March 3.

By utilizing in situ imaging methods such as environmental scanning electron microscopy (ESEM), and newly developed near-ambient pressure photoemission electron microscopy (NAP-PEEM), researchers found that micron-scale Ag nanowires could be dispersed into subnanometer clusters under an oxygen atmosphere.

Ex situ experiments indicated that Ag nanowires were converted into AgOx nanoclusters. Conversely, in situ near-ambient pressure photoelectron spectroscopy (NAP-XPS) directly demonstrated the presence of a transitional state of metallic Ag nanoclusters during dispersion at high temperatures, while the formation of the oxide occurred during the cooling process. The dynamic dispersion of Ag nanowires during CO oxidation was also demonstrated.

Based on experimental and theoretical calculations, chemisorption of oxygen from the O2 atmosphere was shown to be the essential driving force for the dispersion of metallic Ag nanoclusters.

This work provides a new understanding of the role of the O2 atmosphere in oxidative dispersion, which is particularly important for the prediction and control of the dynamic dispersion/redispersion of supported metal catalysts under similar reaction conditions.

Female gannets travel further than male gannets to find fish for their chicks in some years but not others, new research shows.

Scientists tracked breeding gannets from Grassholm Island in Wales over 11 years with tiny GPS devices and by measuring isotopic signatures in their blood.

Male gannets flew an average of 220km to forage for their chicks, while females averaged 260km. Some birds travelled 1,000km on a single trip.

The scientists also found that the two sexes selected different habitats and foraged at different times of day, but some years they were more in sync.

Dr Bethany Clark worked on the research during her PhD at the University of Exeter's Environmental and Sustainability Institute, and now works at BirdLife International.

"Our study used GPS tracking to investigate behaviour and stable isotopes revealed information about their diet," she said.

"The foraging differences we found might indicate that males and females respond differently to changes in environmental conditions, such as how windy it is.

"Their dietary preferences were more consistent over the years: males tended to eat larger fish from closer to shore than females.

"Our results highlight the importance of long-term studies."

Stephen Votier, Professor of Seabird Ecology at the Lyell Centre, Heriot-Watt University, in Edinburgh said: "These birds are true ocean wanderers - travelling thousands of miles at sea throughout their lives to find food. It must be a pretty challenging four and half months raising their chicks each year.

"The sexes are virtually identical so differences are not due to size. Instead, we think males stay close to home because they establish and maintain the nest and perhaps because of subtle differences in taste."

Teachers who participated in a meditation-based teacher development program utilizing the Transcendental Meditation (TM) technique for four months, had significant improvements in emotional exhaustion (the leading factor in burnout), resilience, perceived stress, fatigue, and depression according to a new randomized controlled trial published today in Frontiers in Education.

"Teachers are under high levels of stress as they are asked every day to support their students' learning amidst numerous challenges," said Laurent Valosek, lead author of the study and executive director of the Center for Wellness and Achievement in Education. "This study demonstrates the benefits of meditation for strengthening teachers' mental and physical health. There is a growing body of research on the harmful effects of burnout and the need for resilience. School districts are looking to give their teachers tools for reducing fatigue and emotional exhaustion to support a more effective, sustainable teaching experience and better student outcomes."

BURNOUT AFFECTS TEACHERS WORLDWIDE

It is estimated that 70% of professionals are under constant stress, with over 20% experiencing burnout. Teachers, in particular, face significant daily demands, stress, and fatigue due to their classroom challenges and other professional activities. Burnout includes emotional exhaustion, depersonalization, and reduced sense of personal accomplishment. Signs of teacher burnout include absenteeism from work, impatience with students and colleagues, lack of commitment, poor job performance, and turnover.

TRANSCENDENTAL MEDITATION REDUCES BURNOUT AND IMPROVES RESILIENCE IN TEACHERS

A new randomized control study published in Frontiers in Education involved 78 teachers in the San Francisco Unified School District. The study found that during a four-month period, those practicing the Transcendental Meditation (TM) technique experienced significant improvements in measures of mental, physical, and emotional health.

These findings are consistent with past research on TM showing benefits related to stress reduction and emotional health. This was the first study to investigate the effects of a meditation-based teacher development program on burnout and resilience, two key factors associated with overall mental health.

The primary outcome in the study was emotional exhaustion (the main factor in burnout), as measured by the Maslach Burnout Inventory (MBI). In addition to observing improvements in burnout, the researchers also found improvements in resilience, perceived stress, fatigue, and depression.

CONNECTION BETWEEN TEACHER BURNOUT AND STUDENT STRESS AND LEARNING OUTCOMES

Recent research has begun to show a direct link between teacher stress and the levels of stress in their students. Middle school students in British Columbia showed significant increases in blood cortisol levels linked to their teacher's level of burnout.

Teacher burnout is also associated with reduced student academic performance due to decreased commitment to students, less preparation, and absenteeism. Teacher absenteeism brings results in students learning from less qualified substitute teachers, and eventually results in higher teacher turnover. This research suggests a potential benefit from meditation-based teacher development programs designed to promote emotional wellness and health in teachers and build healthy emotional climates, which are associated with positive student learning.

In a new study by the Yale Department of Immunobiology and Yale Cancer Center, researchers report combined liver and growth factor humanization enhances human red blood cell production and survival in circulation the immunodeficient murine host. The discovery could help in the development of treatments of life-threatening blood disorders, such as myelodysplastic syndrome, and diseases afflicting red blood cells, including sickle cell disease and malaria. The study is published online today in the journal Science.

"Red blood cell diseases, such as thalassemia and sickle cell disease involve approximately 5% of the population worldwide," said Yuanbin Song, MD, adjunct Assistant Professor of Medicine (Hematology) at Yale Cancer Center and co-lead author of the study. "Our findings highlight the unique potential of this model in studies of diseases that intricately link red blood cells and the liver, such as malaria."

"MISTRG" mice were developed in the Yale laboratory of Richard Flavell, PhD, Sterling Professor of Immunobiology at Yale University School of Medicine and Yale Cancer Center and co-senior author of the study to have human growth factors and a human-like immune system. Analysis of the fate of human red cells in MISTRG mice revealed that the mouse liver represents one of the major sites of red blood cell sequestration and destruction. Deletion of the fumarylacetoacetate hydrolase (Fah) gene in MISTRG mice allowed replacement of mouse with human hepatocytes and rescue of human red blood cells in circulation.

Human red blood cells, one of the most common cell types in the body, have been under intense genetic selection throughout human evolution, the damaging consequences of which place a heavy burden on many human populations and healthcare systems.

"This is the first xenotransplantation model with circulating human red cells and it will open novel avenues for the study of disease pathophysiological mechanisms and for preclinical testing of treatments for many diseases, including myelodysplasia, bone marrow failure, sickle cell disease, and others," said Stephanie Halene, MD, PhD, Associate Professor of Medicine (Hematology), Chief of Hematology at Yale Cancer Center and Smilow Cancer Hospital and co-senior author of the study.

It is millions of trillions of times brighter than the sunlight and a whopping 1,000 trillionth of a second, appropriately called the instantaneous light. It is the X-ray Free Electron Laser (XFEL) light that opens a new scientific paradigm. Combining it with AI, an international research team has succeeded in filming and restoring the 3D structure of nanoparticles that share structural similarities with viruses. With the fear of a new pandemic growing around the world due to COVID-19, this discovery is attracting the attention among academic circles for imaging the structure of the virus with both high accuracy and speed.

An international team of researchers from POSTECH, National University of Singapore (NUS), KAIST, GIST, and IBS have successfully analyzed the structural heterogeneities in 3D structures of nanoparticles by irradiating thousands of nanoparticles per hour using the XFEL at Pohang Accelerator Laboratory (PAL) in Korea and restoring 3D multi-models through machine learning. The research team led by Professor Changyong Song and Ph.D. candidate Do Hyung Cho of Department of Physics at POSTECH has driven the international research collaboration to realize it.

Nanoparticles have a peculiar function that may not be available from native bulk materials, and one can control their physical and chemical properties by designing 3D structures and compositions of constituting elements.

The commonality between nanoparticles and viruses is that they exist in the form of independent particles, rather than in crystal-regular, periodic arrangements, and, as such, their structures are not uniform at the nanometer level. To precisely understand their structures, it is necessary to statistically analyze the structure of individual particles using the whole ensemble distribution of structures from thousands to hundreds of thousands of specimens. However, electron microscopes often fall short of providing enough penetration to limit the size of the sample to be probed; conventional X-rays may damage the sample by X-ray radiation itself, making it difficult to obtain sufficient resolution.

The research team overcame the practical limitations of the conventional method by using the X-ray free electron laser and the machine learning method to observe the statistical distribution of the 3D structure of thousands of nanoparticles at the nanometer level. As a result, 3D structures of nanoparticles having a size of 300 nm were obtained with a resolution better than 20 nm.

This achievement was particularly significant for restoring the 3D structure of thousands of nanoparticles using machine learning. Since conventional single-particle imaging techniques often assume an identical 3D structure of the specimens, it was difficult to restore the structure in actual experimental data where the sample structure is not homogeneous. However, with the introduction of the multi-model this time, the researchers succeeded in restoring the representative 3D structures. This research has enabled the classification of nanoparticles into four major shapes, and confirmed that about 40% of them had similar structures.

In addition, through quantitative analysis of the restored 3D structure, the international research collaboration team also uncovered the internal elastic strain distribution accompanied by the characteristic polyhedron structure of the nanoparticles and the inhomogeneous density distribution.

"These findings enable the observation of 3D structure of noncrystalline viral specimens with inhomogeneously distributed internal molecules," explained Professor Changyong Song of POSTECH. "Adding the 3D image restoration algorithm to this through machine learning shows promise to be applicable to studies of macromolecule structures or viruses in living organisms."

As odd as it sounds, many scientists have attempted to place extremely small diamonds inside living cells. Why? Because nanodiamonds are consistently bright and can give us unique knowledge about the inner life of cells over a long time. Now physics researchers at Lund University in Sweden have succeeded in injecting a large number of nanodiamonds directly to the cell interior.

Diamonds are not only sought after for their beauty, but also for their uniquely luminescent properties, at least among scientists. Unlike other fluorescent materials, they do not bleach.

"We actually think of them as a dye. In addition, they are biocompatible", says Elke Hebisch, researcher at solid state physics at Lund University.

Together with Professor Christelle Prinz, she has "injected" fluorescent nano-sized diamonds into living cells.

As a researcher, having such a reporter from inside a cell has many advantages: gaining new knowledge about the cell, as well as monitoring what happens inside the cell over time.

"Especially the latter would be a great step forward, as it is currently possible to take snapshots of, for example, proteins in a cell, but difficult to follow changes over time", explains Elke Hebisch.

What would researchers want to know? It could be about separating healthy cells from diseased ones, targeting disease-causing proteins and other proteins within a specific cell, or monitoring variations in temperature and pH-levels. The knowledge gained could be pure basic research but can also be used to understand diseases and develop drugs.

Other researchers have previously tried to do the same thing, but the diamonds were then taken care of by the cell's "cleaners", the so-called lysosomes, that quickly encapsulated the foreign substance.

"In that scenario,they are not useful since they are trapped in lysosomes and unable to interact with the cell components. Others have managed to get the diamonds into the cell one cell at a time, but that is far too time-consuming to become a realistic alternative", says Christelle Prinz.

The same technique could eventually be used to transport other molecules in order to alter cells or heal diseased cells.

On a final note: is using nanodiamonds expensive? No, Elke Hebisch explains - the quantities needed are extremely small. They are bought in a bottle where they are suspended around in water, and cost the same as regular antibodies.

How it works:

The researchers built nanostraws onto a substrate. They then added cells on the nanostraws , and when mild electrical pulses were applied across the subtrate, the "pores" of the cell membrane dilated and the nanodiamonds went through the nanostraws into the cells. The method was inspired by a similar method developed at Standford University for a different purpose.

BROOKLYN, New York, Wednesday, March 3, 2021 - Machine-learning (ML) systems are becoming pervasive not only in technologies affecting our day-to-day lives, but also in those observing them, including face expression recognition systems. Companies that make and use such widely deployed services rely on so-called privacy preservation tools that often use generative adversarial networks (GANs), typically produced by a third party to scrub images of individuals' identity. But how good are they?

Researchers at the NYU Tandon School of Engineering, who explored the machine-learning frameworks behind these tools, found that the answer is "not very." In the paper "Subverting Privacy-Preserving GANs: Hiding Secrets in Sanitized Images," presented last month at the 35th AAAI Conference on Artificial Intelligence, a team led by Siddharth Garg, Institute Associate Professor of electrical and computer engineering at NYU Tandon, explored whether private data could still be recovered from images that had been "sanitized" by such deep-learning discriminators as privacy protecting GANs (PP-GANs) and that had even passed empirical tests. The team, including lead author Kang Liu, a Ph.D. candidate, and Benjamin Tan, research assistant professor of electrical and computer engineering, found that PP-GAN designs can, in fact, be subverted to pass privacy checks, while still allowing secret information to be extracted from sanitized images.

Machine-learning-based privacy tools have broad applicability, potentially in any privacy sensitive domain, including removing location-relevant information from vehicular camera data, obfuscating the identity of a person who produced a handwriting sample, or removing barcodes from images. The design and training of GAN-based tools are outsourced to vendors because of the complexity involved.

"Many third-party tools for protecting the privacy of people who may show up on a surveillance or data-gathering camera use these PP-GANs to manipulate images," said Garg. "Versions of these systems are designed to sanitize images of faces and other sensitive data so that only application-critical information is retained. While our adversarial PP-GAN passed all existing privacy checks, we found that it actually hid secret data pertaining to the sensitive attributes, even allowing for reconstruction of the original private image."

The study provides background on PP-GANs and associated empirical privacy checks, formulates an attack scenario to ask if empirical privacy checks can be subverted, and outlines an approach for circumventing empirical privacy checks.

The team provides the first comprehensive security analysis of privacy-preserving GANs and demonstrate that existing privacy checks are inadequate to detect leakage of sensitive information. ?

Using a novel steganographic approach, they adversarially modify a state-of-the-art PP-GAN to hide a secret (the user ID), from purportedly sanitized face images. ?

They show that their proposed adversarial PP-GAN can successfully hide sensitive attributes in "sanitized" output images that pass privacy checks, with 100% secret recovery rate. ?

Noting that empirical metrics are dependent on discriminators' learning capacities and training budgets, Garg and his collaborators argue that such privacy checks lack the necessary rigor for guaranteeing privacy.

"From a practical standpoint, our results sound a note of caution against the use of data sanitization tools, and specifically PP-GANs, designed by third parties," explained Garg. "Our experimental results highlighted the insufficiency of existing DL-based privacy checks and the potential risks of using untrusted third-party PP-GAN tools."

Injecting hydrogels containing stem cell or exosome therapeutics directly into the pericardial cavity could be a less invasive, less costly, and more effective means of treating cardiac injury, according to new research from North Carolina State University and the University of North Carolina at Chapel Hill.

Stem cell therapy holds promise as a way to treat cardiac injury, but delivering the therapy directly to the site of the injury and keeping it in place long enough to be effective are ongoing challenges. Even cardiac patches, which can be positioned directly over the site of the injury, have drawbacks in that they require invasive surgical methods for placement.

"We wanted a less invasive way to get therapeutics to the injury site," says Ke Cheng, Randall B. Terry, Jr. Distinguished Professor in Regenerative Medicine at NC State's Department of Molecular Biomedical Sciences and professor in the NC State/UNC-Chapel Hill Joint Department of Biomedical Engineering. "Using the pericardial cavity as a natural "mold" could allow us to create cardiac patches - at the site of injury - from hydrogels containing therapeutics."

In a proof-of-concept study, Cheng and colleagues from NC State and UNC-Chapel Hill looked at two different types of hydrogels - one naturally derived and one synthetic - and two different stem cell-derived therapeutics in mouse and rat models of heart attack. The therapeutics were delivered via intrapericardial (iPC) injection.

Via fluorescent imaging the researchers were able to see that the hydrogel spread out to form a cardiac patch in the pericardial cavity. They also confirmed that the stem cell or exosome therapeutics can be released into the myocardium, leading to reduced cell death and improved cardiac function compared to animals in the group who received only the hydrogel without therapeutics.

The team then turned to a pig model to test the procedure's safety and feasibility. They delivered the iPC injections using a minimally invasive procedure that required only two small incisions, then monitored the pigs for adverse effects. They found no breathing complications, pericardial inflammation, or changes in blood chemistry up to three days post-procedure.

"Our hope is that this method of drug delivery to the heart will result in less invasive, less costly procedures with higher therapeutic efficacy," Cheng says. "Our early results are promising - the method is safe and generates a higher retention rate of therapeutics than those currently in use. Next we will perform additional preclinical studies in large animals to further test the safety and efficacy of this therapy, before we can start a clinical trial."

"I anticipate in a clinical setting in the future, iPC injection could be performed with pericardial access similar to the LARIAT procedure. In that regard, only one small incision under local anesthesia is needed on the patient's chest wall," says Dr. Joe Rossi, associate professor in the division of cardiology at UNC-Chapel Hill and co-author of the paper.

CHAMPAIGN, Ill. -- A smartphone app called Harbor, currently under development by researchers at the University of Illinois Urbana-Champaign, teaches young adults how to talk to a peer if they are concerned about that other person's drinking or drug use.

Designed for people ages 18-29, Harbor teaches young adults how they can "act as first responders for their close friends who demonstrate risky substance use behaviors," according to the app's lead developer, social work professor Douglas C. Smith. Smith, the director of the Center for Prevention Research and Development at the U. of I., focuses his research on substance use and interventions for young people.

While young adults have the highest rates of substance use, they are also the people least likely to seek treatment, he said.

"If you're an individual who gets referred to treatment, or who is in need of treatment, it's pretty likely that people in your social network are worried about you," he said. "And there's probably a mix of people in your social network who also have elevated substance use as well."

In an online survey of more than 450 young adults conducted for the current study, 45% of the respondents indicated that they were concerned about a close friend's drug or alcohol use. The study was published in the Journal of Medical Internet Research.

"If they're responding affirmatively to that question, there's a good chance their friend is probably using at some sort of risky level," said graduate student Kyle M. Bennett, the first author of the study.

"They're probably not just an occasional user; they're probably going out frequently and experiencing some of those nasty side effects of whatever substance they may be using."

However, while many young people may be troubled by friends' drug or alcohol use, many of them are also uncertain how to talk with them about it, Bennett said.

"You hear this often: 'I would have done something, but I just didn't know what to do or I didn't know what to say or how to approach the topic,'" Bennett said. "The Harbor app guides them in supporting their friend without being confrontational or enabling."

The app prompts the user to answer several questions about their friend's substance use behaviors and provides feedback on the potential seriousness - a feature that may be especially helpful to people who feel conflicted about intervening, Smith said.

Smith said the idea for the mobile phone app sprang from a prior project, funded by a five-year grant from the National Institute on Alcohol Abuse and Alcoholism, that explored the efficacy of having young people with alcohol or marijuana problems invite a close friend to participate in some of their treatment sessions with them to provide social support.

"Since young adults have really low rates of coming to treatment, we thought that this peer model might be a way of expanding the benefits of treatment to people who don't usually seek it," Smith said. "A surprising finding from that study was that both the client and their friend made changes in their substance use behaviors and got better within six months."

That study, published in the Journal of Substance Abuse Treatment in 2015, found that both the client and their friend reduced their binge drinking and increased the number of days that they abstained. Smith's co-authors were Western Ontario University psychology professor Tara Dumas and then-U. of I. graduate students Jordan P. Davis and the late Daniel J. Ureche.

Harbor provides the app user with possible text messages and dialogues for conveying their concerns to their friend. Smith said a challenge for the team was writing messages that could be applied in differing situations without being overly generic and that also sounded conversational and reflected young people's speech patterns.

"Ultimately, you're trying to communicate a message while encouraging them to adopt some of these practices and empowering them to put it in their own words when they talk with their friend," Smith said.

When young adults in the study reviewed the sample scripts and messages, "more than 95% of them indicated the scripts would be useful in talking with their friends about their substance use," Bennett said. "And about 98% of respondents rated the script dialogues as realistic. If young adults felt the language in the scripts was inauthentic, I think it's safe to assume they would be less likely to use the app."

Participants also were asked to evaluate the language in the app's messages and rate each of them as supportive, enabling or confrontational. While most of the participants accurately identified the enabling and confrontational responses, they were less consistent at recognizing the supportive responses, Smith said.

The researchers were uncertain why that occurred but said it may have been because participants had not been given the app's educational module first and lacked the information or personal experience to accurately interpret supportive responses.

The team is currently refining and beta-testing the Harbor app to deploy it in a controlled trial with young adults and their friends in a clinic setting this spring.

The coronavirus pandemic has drawn new attention to the digital divide, as the need for online schooling and working from home has disproportionately hurt those without computer equipment and skills.

Research by Paul A. Pavlou, dean of the C. T. Bauer College of Business at the University of Houston, found that people with basic Information Technology (IT) skills - including the ability to use email, copy and paste files and work with an Excel spreadsheet - are more likely to be employed, even in jobs that aren't explicitly tied to those skills.

People with more advanced IT skills generally earned higher salaries, the researchers found. The work is described in Information Systems Research.

"Unemployment and low wages remain pressing societal challenges in the wake of increased automation, more so for traditionally-disadvantaged groups in the labor market, such as women, minorities, and the elderly," the researchers wrote. "However, workers who possess relevant IT skills might have an edge in an increasingly digital economy."

The findings, Pavlou said, reinforce the need for robust public policy to ensure people, especially women, older workers and others who are more likely to face employment discrimination, have the basic IT skills needed for the modern working world, since few companies provide on-the-job training in those skills.

"Very few people can get these skills from their employer. Workers are expected to obtain these IT skills themselves, in order to get a job in the first place" he said. "And the less-privileged population they are, the harder time they have obtaining these skills that require computer equipment and internet access."

That leaves many workers, especially from under-represented populations in the labor market, unable to even apply for work, as more job applications - and now, interviews - are handled online.

In addition to Pavlou, co-authors on the paper include Hilal Atasoy of Rutgers University and Rajiv Banker from Temple University.

The analysis was conducted using two datasets from the Turkish Statistical Institute, and Pavlou said the findings are especially relevant for the developing world, where people are less likely to have IT skills and access to computer equipment than they are in the United States.

But the pandemic has laid bare unequal access to technology in the United States, too, as schools and universities struggle to provide students with computers, internet hotspots and other equipment to continue their educations online.

The work thus has implications for marginalized workers in the United States and other developed countries, Pavlou said. That includes women and older workers, who are more likely to opt out of the labor force if they cannot work from home - jobs that are more likely to require at least basic tech savvy.

"The digital divide is a major societal problem," Pavlou said. "I think the pandemic will make it even more pronounced. People with basic IT skills will have access to more opportunities, and it is imperative for educational institutions to provide these IT skills, especially in traditionally-disadvantaged populations."

Scientists at the University of Bath in the UK have found a way to bind together two photons of different colours, paving the way for important advancements in quantum-electrodynamics - the field of science that describes how light and matter interact. In time, the team's findings are likely to impact developments in optical and quantum communication, and precision measurements of frequency, time and distances.

APPLE AND WAVE: THEY BOTH HAVE A MASS

An apple falling from a tree has velocity and mass, which together give it momentum. 'Apple energy' derived from motion depends on the fruit's momentum and mass.

Most people find the concept of momentum and energy (and therefore mass) an easy one to grasp when it is associated with solid objects. But the idea that non-material objects, such as light waves (everything from sunlight to laser radiation), also have a mass is surprising to many. Among physicists, however, it's a well-known fact. This apparently paradoxical idea that waves have a mass marks the place where quantum physics and the physical world come together.

The wave-particle duality, proposed by French physicist Louis de Broglie in 1924, is a powerful concept that describes how every particle or quantum entity can be described as either a particle or a wave. Many so-called quasiparticles have been discovered that combine either two different types of matter particles, or light waves bound to a particle of matter. A list of exotic quasiparticles includes phonons, plasmons, magnons and polaritons.

The team of physicists at Bath has now reported a way to create quasiparticles that bind together two differently coloured particles of light. They have named these formations photon-photon polaritons.

DETECTING PHOTON-PHOTON POLARITONS

The opportunity to discover, and manipulate, photon-photons is possible thanks to the relatively new development of high-quality microresonators. For light, microresonators act as miniature racetracks, with photons zipping around the internal structure in loops. The signature left by photon-photons in the light exiting the microresonator can be linked to the Autler-Townes effect, a peculiar phenomenon in quantum theory that describes strong photon-atom interactions. To achieve this effect in microresonators, a laser is tuned to the specific resonance frequency where a photon is expected to be absorbed, yet no resonance absorption happens. Instead, the photon-photon interaction makes up two new resonance frequencies away from the old one.

A significant feature that has emerged from the Bath research is that the microresonator provided a whole set of split resonances, where each photon-photon pair displayed its own momentum and energy, allowing the researchers to apply the quasiparticle concept and calculate mass. According to the researchers' predictions, photon-photons are 1,000+ times lighter than electrons.

Professor Dmitry Skryabin, the physicist who led the research, said: "We now have a situation where microresonators - which are millimeter-scale objects - behave like giant atoms. The artificial atoms concept is rapidly gaining ground in the quantum-electrodynamics of microwaves in superconducting circuits, while here we are looking at the similar opportunity in the optical range of frequencies.

"The small mass of photon-photons could lead to further developments of many important analogies between light and fluids, where other families of quasiparticles have already being used."

PhD student Vlad Pankratov, who participated in the project, said: "After a year of running models and collecting data, these are incredibly exciting findings for us. The potential applications of our results are in the terabit and quantum optical communication schemes, and in the area of precision measurements."

ENDS.

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Boulder, Colo., USA: Several new articles were published online ahead of
print for Geology in February. Topics include stress in survivor
plants following the collapse of land ecosystems, the Gulf of Aden, whether
the Denali fault is still active, the first reported Burgess Shale–type
fauna rediscovered, and redefining the age of the lower Colorado River.
These Geology articles are online at

http://geology.geoscienceworld.org/content/early/recent

.

Discovery of a large subsoil nitrate reservoir in an arroyo floodplain
and associated aquifer contamination

Benjamin S. Linhoff; John J. Lunzer

Abstract:
In an area of elevated nitrate (NO3) groundwater concentrations
in the northern Chihuahuan Desert in central New Mexico (United States), a
large reservoir of nitrate was found in the subsoil of an arroyo
floodplain. Nitrate inventories in the floodplain subsoils ranged from
10,000 to 38,000 kg NO3-N/ha—over twice as high as any
previously measured arid region. The floodplain subsoil NO3
reservoir was over 100 times higher than the adjacent desert (59–95 kg NO 3-N/ha). Chloride mass balance calculations of subsoils indicate
arroyo floodplain subsoils have undergone negative recharge since 2600–8600
yr ago, while the surrounding desert has had negative recharge since
13,000–17,000 yr ago. Compared to the adjacent desert, plant communities
are larger and more abundant in the floodplain, though subsoil NO 3 is apparently not utilized. We demonstrate that NO3
accumulates in the subsoil of the floodplain through evaporation of monsoon
season precipitation funneled into the arroyo. Through a one-dimensional
vadose zone model, we show that the NO3 inventories in the
arroyo floodplain could be acquired 8 to 75 times faster than through
atmospheric deposition through the lateral movement.

View article:
https://pubs.geoscienceworld.org/gsa/geology/article-abstract/doi/10.1130/G47916.1/594886/Discovery-of-a-large-subsoil-nitrate-reservoir-in

Homeostatic response of Aptian gymnosperms to changes in atmospheric CO 2 concentrations

Germán Mora; Ana M. Carmo; William Elliott

Abstract:
The sensitivity of plant carbon isotope fractionation (13Δleaf) to changes in atmospheric CO2 concentrations ( Ca) is the subject of heavy debate, with some studies
finding no sensitivity, while others show a strong dependency. We tested
the hypothesis of photosynthetic homeostasis by using δ13C of
n-alkanes, cuticles, and bulk organic matter of gymnosperm-rich rocks
(Arundel Clay) from two sites deposited during the Aptian, a time that
experienced significant Ca variations. Our results show
no effect of Ca on 13Δleaf, and a
relatively constant Ci/Ca (0.64 ±
0.04, 1σ; i—intercellular space), a value that is similar to that of modern
gymnosperms. These results suggest that Aptian gymnosperms used homeostatic
adjustments with rising Ca, probably involving
increased carbon assimilation and/or stomatal closure, a response also
found in modern gymnosperms. The similarity between Aptian and modern
gymnosperms suggests that the processes responsible for regulating CO 2 and water vapor exchange during photosynthesis have remained
unaltered in gymnosperms for the past 128 m.y.

View article:
https://pubs.geoscienceworld.org/gsa/geology/article-abstract/doi/10.1130/G48037.1/594887/Homeostatic-response-of-Aptian-gymnosperms-to

The Parker Quarry Lagerstätte of Vermont—The first reported Burgess Shale–type fauna rediscovered

Giovanni Pari; Derek E.G. Briggs; Robert R. Gaines

Abstract:
Soft-bodied fossils of Cambrian age, now known as Burgess Shale–type
biotas, were first described from the Parker Slate of the northwest Vermont
(USA) slate belt in the late 19th century, 25 years before the
discovery of the Burgess Shale in British Columbia, Canada. Here, we report
the rediscovery of fossiliferous horizons at Parker’s Cobble, the site of
the original quarry, which was thought to have been exhausted by
excavation. New discoveries include a radiodont, multiple specimens of a
new bivalved arthropod, a priapulid, and other undescribed forms. Pervasive
soft-sediment deformation suggests accumulation near the toe of a steep
unstable slope, similar to the setting of the Burgess Shale. Although
fossils are rare, the exceptional preservation of some soft-bodied taxa
suggests that recovered diversity was limited by transport into an
inhospitable benthic setting rather than by decay, and this implies a
potential for future discoveries of new taxa.

View article:
https://pubs.geoscienceworld.org/gsa/geology/article-abstract/doi/10.1130/G48422.1/594888/The-Parker-Quarry-Lagerstatte-of-Vermont-The-first

Redefining the age of the lower Colorado River, southwestern United
States

R.S. Crow; J. Schwing; K.E. Karlstrom; M. Heizler; P.A. Pearthree ...

Abstract:
Sanidine dating and magnetostratigraphy constrain the timing of integration
of the lower Colorado River (southwestern United States and northern
Mexico) with the evolving Gulf of California. The Colorado River arrived at
Cottonwood Valley (Nevada and Arizona) after 5.24 Ma (during or after the
Thvera subchron). The river reached the proto–Gulf of California once
between 4.80 and 4.63 Ma (during the C3n.2r subchron), not at 5.3 Ma and 5.0 Ma as previously proposed. Duplication of section across
newly identified strands of the Earthquake Valley fault zone (California)
probably explains the discrepancy. The data also imply the start of focused
plate motion and basin development in the Salton Trough (California) at
6–6.5 Ma and relative tectonic stability of the southernmost part of the
lower Colorado River corridor after its integration. After integration, the
Colorado River quickly incised through sediment-filled basins and divides
between them as it also likely excavated Grand Canyon (Arizona). The
liberated sediment from throughout the system led to deposition of hundreds
of meters of Bullhead Alluvium downstream of Grand Canyon after 4.6 Ma as
the river adjusted to its lower base level.

View article:
https://pubs.geoscienceworld.org/gsa/geology/article-abstract/doi/10.1130/G48080.1/594889/Redefining-the-age-of-the-lower-Colorado-River

Subduction erosion and crustal material recycling indicated by adakites
in central Tibet

Zong-Yong Yang; Qiang Wang; Lu-Lu Hao; Derek A. Wyman; Lin Ma ...

Abstract:
Subduction erosion is important for crustal material recycling and is
widespread in modern active convergent margins. However, such a process is
rarely identified in fossil convergent systems, which casts doubt on the
importance of subduction erosion through the geological record. We report
on ca. 155 Ma Kangqiong (pluton) intrusive rocks of a Mesozoic magmatic arc
in the southern Qiangtang terrane, central Tibet. These rocks mainly
consist of trondhjemites and tonalites and are similar to slab-derived
adakites with mantle-like zircon oxygen isotope compositions (δ 18O = 5.2‰–5.6‰), they display more evolved Sr-Nd isotopes and
higher Th/La relative to mid-oceanic ridge basalts from the Bangong-Nujiang
suture, and they contain abundant amphibole and biotite. These
characteristics indicate magma generation via H2O-fluxed melting
of eroded forearc crust debris with subducted oceanic crust at 1.5–2.5 GPa
and 700–800 °C. In addition, the intrusions are exposed <20 km north of
the Bangong-Nujiang suture. Given the formation of adakites, narrow
arc-suture distance, migration of the Jurassic frontal arc toward the
continent interior, and other independent geological archives, we suggest
that the hydrated forearc crust materials were removed from the overlying
plate and carried into the mantle by subduction erosion. Our study provides
the first direct magmatic evidence for a subduction erosion process in
pre-Cenozoic convergent systems, which confirms an important role for such
processes in subduction-zone material recycling.

View article:
https://pubs.geoscienceworld.org/gsa/geology/article-abstract/doi/10.1130/G48486.1/594890/Subduction-erosion-and-crustal-material-recycling

Abrasion regimes in fluvial bedrock incision

Alexander R. Beer; Michael P. Lamb

Abstract:
River incision into bedrock drives landscape evolution and couples surface
changes to climate and tectonics in uplands. Mechanistic bedrock erosion
modeling has focused on plucking—the hydraulic removal of large loosened
rock fragments—and on abrasion—the slower fracturing-driven removal of rock
due to impacts of transported sediment—which produces sand- or silt-sized
fragments at the mineral grain scale (i.e., wear). An abrasion subregime
(macro-abrasion) has been hypothesized to exist under high impact energies
typical of cobble or boulder transport in mountain rivers, in which larger
bedrock fragments can be generated. We conducted dry impact abrasion
experiments across a wide range of impact energies and found that
gravel-sized fragments were generated when the impact energy divided by
squared impactor diameter exceeded 1 kJ/m2. However, the total
abraded volume followed the same kinetic-energy scaling regardless of
fragment size, holding over 13 orders of magnitude in impact energy and
supporting a general abrasion law. Application to natural bedrock rivers
shows that many of them likely can generate large fragments, especially in
steep mountain streams and during large floods, transporting boulders in
excess of 0.6 m diameter. In this regime, even single impacts can cause
changes in riverbed topography that may drive morphodynamic feedbacks.

View article:
https://pubs.geoscienceworld.org/gsa/geology/article-abstract/doi/10.1130/G48466.1/594891/Abrasion-regimes-in-fluvial-bedrock-incision

External signal preservation in halokinetic stratigraphy: A discrete
element modeling approach

Zoë A. Cumberpatch; Emma Finch; Ian A. Kane

Abstract:
Subsurface salt movement in the absence of external tectonic forces can
affect contemporaneous sediment deposition, mask allocyclic signals, and
deform older strata. We used a discrete element model (DEM) to better
understand salt-related modification of a sedimentary sequence with an
increasing sedimentation rate. This permitted quantification of thinning
rates and analysis of the lateral extent of synkinematic layers. Results
show realistic evolution of salt-related faults, defining two
salt-withdrawal basins, beyond which strata are undeformed. Thinning of
stratigraphy is four times greater between the salt flank and crest than
between the undeformed zone and flank, confirming an intense zone of
halokinetic modulation adjacent to the diapir. Early, slowly aggrading
layers are isolated within the salt-withdrawal basin and strongly
influenced by salt growth, whereas later, quickly aggrading layers are more
laterally extensive, matching inferences made from subsurface and outcrop
data. Halokinetic modulation reduces up the stratigraphic section,
mirroring observations around the Pierce diapirs, in the North Sea,
offshore UK. Our DEM provides quantitative insights into the dynamic
interplay between halokinetic and allocyclic controls on salt-stratigraphic
relationships.

View article:
https://pubs.geoscienceworld.org/gsa/geology/article-abstract/doi/10.1130/G48448.1/594892/External-signal-preservation-in-halokinetic

Extreme Quaternary plate boundary exhumation and strike slip localized
along the southern Fairweather fault, Alaska, USA

Richard O. Lease; Peter J. Haeussler; Robert C. Witter; Daniel F. Stockli;
Adrian M. Bender ...

Abstract:
The Fairweather fault (southeastern Alaska, USA) is Earth’s
fastest-slipping intracontinental strike-slip fault, but its long-term role
in localizing Yakutat–(Pacific–)North America plate motion is poorly
constrained. This plate boundary fault transitions northward from pure
strike slip to transpression where it comes onshore and undergoes a
<25°, 30-km-long restraining double bend. To the east, apatite (U-Th)/He
(AHe) ages indicate that North America exhumation rates increase stepwise
from ~0.7 to 1.7 km/m.y. across the bend. In contrast, to the west, AHe
age-depth data indicate that extremely rapid 5–10 km/m.y. Yakutat
exhumation rates are localized within the bend. Further northwest, Yakutat
AHe and zircon (U-Th)/He (ZHe) ages gradually increase from 0.3 to 2.6 Ma
over 150 km and depict an interval of extremely rapid >6–8 km/m.y.
exhumation rates that increases in age away from the bend. We interpret
this migration of rapid, transient exhumation to reflect prolonged
advection of the Cenozoic–Cretaceous sedimentary cover of the eastern
Yakutat microplate through a stationary restraining bend along the edge of
the North America plate. Yakutat cooling ages imply a long-term strike-slip
rate (54 ± 6 km/m.y.) that mimics the millennial (53 ± 5 m/k.y.) and
decadal (46 mm/yr) rates. Fairweather fault slip can account for all
Pacific–North America relative plate motion throughout Quaternary time and
indicates stability of highly localized plate boundary strike slip on a
single fault where extreme rock uplift rates are persistently localized
within a restraining bend.

View article:
https://pubs.geoscienceworld.org/gsa/geology/article-abstract/doi/10.1130/G48464.1/594893/Extreme-Quaternary-plate-boundary-exhumation-and

Phanerozoic variation in dolomite abundance linked to oceanic anoxia

Mingtao Li; Paul B. Wignall; Xu Dai; Mingyi Hu; Haijun Song

Abstract:
The abundance of dolomitic strata in the geological record contrasts with
the general rarity of locations where dolomite forms today, a discrepancy
that has long posed a problem for their interpretation. Recent culture
experiments show that dolomite can precipitate at room temperature, raising
the possibility that many ancient dolomites may be of syngenetic origin. We
compiled a large geodata set of secular variations in dolomite abundance in
the Phanerozoic, coupled with compilations of genus richness of marine
benthic invertebrates and sulfur-isotope variations in marine carbonates.
These data show that dolomite abundance is negatively correlated to genus
diversity, with four dolomite peaks occurring during mass extinctions.
Dolomite peaks also correspond to the rapid increase in sulfur-isotope
composition (δ34S), an indicator of enhanced sulfate reduction,
in anoxic oceans. These results confirm that variations in dolomite
abundance during the Phanerozoic were closely linked with changes in marine
benthic diversity, with both in turn related to oceanic redox conditions.

View article:
https://pubs.geoscienceworld.org/gsa/geology/article-abstract/doi/10.1130/G48502.1/594894/Phanerozoic-variation-in-dolomite-abundance-linked

Metal-induced stress in survivor plants following the end-Permian
collapse of land ecosystems

Daoliang Chu; Jacopo Dal Corso; Wenchao Shu; Song Haijun; Paul B., Wignall
...

Abstract:
Teratological spores and pollen are widespread in sediments that record the
Permian- Triassic mass extinction. The malformations are thought to be the
result of extreme environmental conditions at that time, but the mutagenic
agents and the precise timing of the events remain unclear. We examined the
abundance of teratological sporomorphs and metal concentrations in a
Permian-Triassic tropical peatland succession of southwestern China. We
find a significant peak of spore tetrads of lycopsid plants (as much as 19%
of all sporomorphs) coeval with increases in Cu and Hg concentrations above
the main terrestrial extinction interval, which marks the loss of Permian Gigantopteris forests, increased wildfire activity, and the
disappearance of coal beds. Thus, in tropical peatlands, mutagenesis
affected only surviving plants. Mutagenesis was likely caused by metal
toxicity, linked to increased Hg and Cu loading, but was not itself a
direct cause of the terrestrial crisis.

View article:
https://pubs.geoscienceworld.org/gsa/geology/article-abstract/doi/10.1130/G48428.1/594557/Biomineralization-of-the-Cambrian-chancelloriids

Inherited lithospheric structures control arc-continent collisional
heterogeneity

M.S. Miller; P. Zhang; M.P. Dahlquist; A.J. West; T.W. Becker ...

Abstract:
From west to east along the Sunda-Banda arc, convergence of the
Indo-Australian plate transitions from subduction of oceanic lithosphere to
arc-continent collision. This region of eastern Indonesia and Timor-Leste
provides an opportunity for unraveling the processes that occur during
collision between a continent and a volcanic arc, and it can be viewed as
the temporal transition of this process along strike. We collected a range
of complementary geological and geophysical data to place constraints on
the geometry and history of arc-continent collision. Utilizing ~4 yr of new
broadband seismic data, we imaged the structure of the crust through the
uppermost mantle. Ambient noise tomography shows velocity anomalies along
strike and across the arc that are attributed to the inherited structure of
the incoming and colliding Australian plate. The pattern of anomalies at
depth resembles the system of salients and embayments that is present
offshore western Australia, which formed during rifting of east Gondwana.
Previously identified changes in geochemistry of volcanics from Pb isotope
anomalies from the inner arc islands correlate with newly identified
velocity structures representing the underthrusted and subducted
Indo-Australian plate. Reconstruction of uplift from river profiles from
the outer arc islands suggests rapid uplift at the ends of the islands of
Timor and western Sumba, which coincide with the edges of the
volcanic-margin protrusions as inferred from the tomography. These findings
suggest that the tectonic evolution of this region is defined by inherited
structure of the Gondwana rifted continental margin of the incoming plate.
Therefore, the initial template of plate structure controls orogenesis.

View article
:
https://pubs.geoscienceworld.org/gsa/geology/article-abstract/doi/10.1130/G48246.1/594556/Inherited-lithospheric-structures-control-arc

Biomineralization of the Cambrian chancelloriids

Hao Yun; Xingliang Zhang; Glenn A. Brock; Luoyang Li; Guoxiang Li

Abstract:
As extinct animals that flourished during the Cambrian explosion,
chancelloriids have a unique body plan lacking guts but with a flexible
integument and a suite of star-shaped, hollow sclerites. Due to this body
plan, along with the paucity of knowledge on sclerite biomineralization,
the phylogenetic position of chancelloriids within the Metazoa is still
controversial. Integration of analyses of diverse fossils from Cambrian
stage 2 to the Wuliuan Stage of China and Australia indicates that
chancelloriid sclerites possess an encasement-like organic layer and a
fibrous aragonitic layer. The organic layer is inferred to be a specialized
trait derived from the epidermal integument of the animal body. The
sclerites were likely biomineralized by using the outer organic layer as a
template to absorb cations and precipitate crystal nuclei, reflecting a
strategy adopted by a range of eumetazoans with a developed epidermis.
Therefore, the hypothesis that chancelloriids represent an
epitheliozoan-grade animal and an early explorer of template-based
biomineralization is supported.

View article:
https://pubs.geoscienceworld.org/gsa/geology/article-abstract/doi/10.1130/G48428.1/594557/Biomineralization-of-the-Cambrian-chancelloriids

High-precision U-Pb age constraints on the Permian floral turnovers,
paleoclimate change, and tectonics of the North China block

Qiong Wu; Jahandar Ramezani; Hua Zhang; Jun Wang; Fangui Zeng ...

Abstract:
The Permian marine-terrestrial system of the North China block provides an
exceptional window into the evolution of northern temperate ecosystems
during the critical transition from icehouse to greenhouse following the
late Paleozoic ice age (LPIA). Despite many studies on its rich hydrocarbon
reserves and climate-sensitive fossil flora, uncertain temporal constraints
and correlations have hampered a thorough understanding of the records of
geologic, biologic, and climatic change from the North China block. We
present a new chronostratigraphy based on high-precision U-Pb chemical
abrasion–isotope dilution–thermal ionization mass spectrometry (CA-ID-TIMS)
geochronology of tuffs from a near-complete latest Carboniferous–Permian
succession in North China. The results indicate that the predominance of
continental red beds, climate aridification, and the disappearance of coals
and characteristic tropical flora were well under way during the Cisuralian
(Early Permian) in the North China block, significantly earlier than
previously thought. A nearly 20 m.y. hiatus spanning the early Kungurian to
the mid-Guadalupian (or later) is revealed in the northern North China
block to have close temporal and spatial associations with the closure
and/or subduction of the Paleo-Asian Ocean and its related tectonic
convergence. This long hiatus was concomitant with the prominent loss of
the highly diverse and abundant Cathaysian floras and the widespread
invasion of the monotonous Angaran floras under arid climate conditions in
the North China block. Similarities in the floral and climate shift
histories between Euramerica and North China suggest that aside from the
regional tectonic controls and continental movement, extensive volcanism
during the Cisuralian may have played a major role in the global warming
and aridification in the aftermath of the LPIA.

View article:
https://pubs.geoscienceworld.org/gsa/geology/article-abstract/doi/10.1130/G48051.1/594558/High-precision-U-Pb-age-constraints-on-the-Permian

Apatite nanoparticles in 3.46–2.46 Ga iron formations: Evidence for
phosphorus-rich hydrothermal plumes on early Earth

Birger Rasmussen; Janet R. Muhling; Alexandra Suvorova; Woodward W. Fischer

Abstract:
Phosphorus is an essential nutrient that is thought to have regulated
primary productivity in global oceans after the advent of oxygenic
photosynthesis. The prime source of seawater phosphorus is regarded to be
continental weathering of phosphate minerals. Ancient seawater phosphorus
concentrations have been constrained using the phosphorus content of
iron-rich chemical sediments—banded iron formations (BIFs); however, the
removal processes and depositional phases remain unclear. Here we report
that nanometer-sized apatite crystals (<500 nm) are ubiquitous in
3.46–2.46 Ga BIFs and cherts from the Kaapvaal (South Africa) and Yilgarn
and Pilbara (Western Australia) cratons. The apatite is uniformly dispersed
in a chemical sediment comprising greenalite nanoparticles, which were
encased in very early diagenetic silica cement that limited compaction and
chemical reactions. The lack of organic carbon (below detection; <0.3
wt%) and absence of primary iron oxides implies that the phosphorus was not
derived from the degradation of organic matter or seawater scavenging by
oxide particles. Instead, the occurrence of apatite in sediments derived
from hydrothermally sourced Fe2+ and SiO2(aq)
suggests that phosphorus too was derived from vent plumes. Today, seawater
P is rapidly removed from vent fluids due to scavenging by oxidized Fe 2+. However, prior to the Great Oxidation Event (2.45–2.32 Ga),
dissolved phosphorus released during anoxic alteration of seafloor basalts
escaped the iron-oxidation trap. Our results point to the existence of a
submarine hydrothermal flux of dissolved phosphorus that supplied nutrients
to the early anoxic oceans. High amounts of seawater P may help to explain
why phosphorus is ubiquitous in cell biology—it was not limiting during the
origin and early evolution of life.

View article:
https://pubs.geoscienceworld.org/gsa/geology/article-abstract/doi/10.1130/G48374.1/594559/Apatite-nanoparticles-in-3-46-2-46-Ga-iron

Recalibrating Rodinian rifting in the northwestern United States

Daniel T. Brennan; Zheng-Xiang Li; Kai Rankenburg; Noreen Evans; Paul K.
Link ...

Abstract:
A lack of precise age constraints for Neoproterozoic strata in the
northwestern United States (Washington State), including the Buffalo Hump
Formation (BHF), has resulted in conflicting interpretations of Rodinia
amalgamation and breakup processes. Previous detrital zircon (DZ) studies
identified a youngest ca. 1.1 Ga DZ age population in the BHF, interpreted
to reflect mostly first-cycle sourcing of unidentified but proximal
magmatic rocks intruded during the amalgamation of Rodinia at ca. 1.0 Ga.
Alternatively, the ca. 1.1 Ga DZ population has been suggested to represent
a distal source with deposition occurring during the early phases of
Rodinia rifting, more than 250 m.y. after zircon crystallization. We
combined conventional laser-ablation split-stream analyses of U-Pb/Lu-Hf
isotopes in zircon with a method of rapid (8 s per spot) U-Pb analysis to
evaluate these opposing models. Our study of ~2000 DZ grains from the BHF
identified for the first time a minor (~1%) yet significant ca. 760 Ma
population, which constrains the maximum depositional age. This new
geochronology implies that the BHF records early rift deposition during the
breakup of Rodinia and correlates with sedimentary rocks found in other
late Tonian basins of southwestern Laurentia.

View article:
https://pubs.geoscienceworld.org/gsa/geology/article-abstract/doi/10.1130/G48435.1/594560/Recalibrating-Rodinian-rifting-in-the-northwestern

Gulf of Aden spreading does not conform to triple-junction formation

Khalid A. Almalki; Peter G. Betts

Abstract:
The Gulf of Aden represents an evolving example of a juvenile ocean system
and is considered the most evolved rift arm of the Afar triple junction. We
have undertaken analysis of recent coupled satellite and marine
potential-field data to understand the first-order crustal architecture
along the entire length of the gulf. Our interpretation suggests the Gulf
of Aden has three domains with distinct free-air gravity and magnetic
characteristics. These domains record a progression from active seafloor
spreading in the eastern domain, through isolated and discontinuous
spreading segments in the central domain, to active continental rifting in
the western domain immediately adjacent to the Afar triple junction.
Forward models suggest the presence of transitional crust, which displays
linear magnetic stripe–like anomalies that bound oceanic stripes in the
central domain and covering the majority of the western domain. Magnetic
anomalies differ from magnetic stripes sensu stricto because they
are discontinuous and cannot be correlated along the length of the gulf.
Detection of northwest-southeast extension in the central domain based on
magnetic stripe orientation is inconsistent with the regional
northeast-southwest extension. Our observations reflect heterogeneous
opening of the Gulf of Aden basins, in which spreading is migrating toward
Afar as a series of isolated spreading segments, rather than initiating at
the junction as proposed by classical platetectonic theory. This mechanism
of ocean initiation is inconsistent with transtensional models that involve
wholesale tearing of continental crust and contradicts conceptual models
that rely on the Afar plume in initiating or driving the extension.

View article:
https://pubs.geoscienceworld.org/gsa/geology/article-abstract/doi/10.1130/G48529.1/594561/Gulf-of-Aden-spreading-does-not-conform-to-triple

Is the Eastern Denali fault still active?

Minhee Choi; David W. Eaton; Eva Enkelmann

Abstract:
The Denali fault, a transcurrent fault system that extends from
northwestern Canada across Alaska toward the Bering Sea, is partitioned
into segments that exhibit variable levels of historical seismicity. A pair
of earthquakes (M 6.2 and 6.3) on 1 May 2017, in proximity to the Eastern
Denali fault (EDF), exhibited source mechanisms and stress conditions
inconsistent with expectations for strike-slip fault activation. Precise
relocation of ~1500 aftershocks revealed distinct fault strands that are
oblique to the EDF. Calculated patterns of Coulomb stress show that the
first earthquake likely triggered the second one. The EDF parallels the
Fairweather transform, which separates the obliquely colliding Yakutat
microplate from North America. In our model, inboard transfer of stress is
deforming and shortening the mountainous region between the EDF and the
Fairweather transform. This is supported by historical seismicity
concentrated southwest of the EDF, suggesting that it now represents a
structural boundary that controls regional deformation but is no longer an
active fault.

View article:
https://pubs.geoscienceworld.org/gsa/geology/article-abstract/doi/10.1130/G48461.1/594562/Is-the-Eastern-Denali-fault-still-active

Wide-blocky veins explained by dependency of crystal growth rate on
fracture surface type: Insights from phase-field modeling

Liene Spruženiece; Michael Späth; Janos L. Urai; Estibalitz Ukar; Michael
Selzer ...

Abstract:
Vein microstructures contain a wealth of information on coupled chemical
and mechanical processes of fracturing, fluid transport, and crystal
growth. Numerical simulations have been used for exploring the factors
controlling the development of vein microstructures; however, they have not
been quantitatively validated against natural veins. Here we combined
phase-field modeling with microtextural analysis of previously unexplained
wide-blocky calcite veins in natural limestone and of the fresh fracture
surface in this limestone. Results show that the wide-blocky vein textures
can only be reproduced if ~10%–20% of crystals grow faster than the rest.
This fraction corresponds to the amount of transgranularly broken grains
that were observed on the experimental fracture surfaces, which are
dominantly intergranular. We hypothesize that transgranular fractures allow
faster growth of vein minerals due to the lack of clay coatings and other
nucleation discontinuities that are common along intergranular cracks. Our
simulation results show remarkable similarity to the natural veins and
reproduce the nonlinear relationship between vein crystal width and vein
aperture. This allows accurate simulations of crystal growth processes and
related permeability evolution in fractured rocks.

View article:
https://pubs.geoscienceworld.org/gsa/geology/article-abstract/doi/10.1130/G48472.1/594563/Wide-blocky-veins-explained-by-dependency-of

In a world first, an international team of researchers has read an unopened letter from Renaissance Europe - without breaking its seal or damaging it in any way.

The research, published in Nature Communications, describes how an X-ray scanner used in dental research and 'virtual unfolding' allowed the interdisciplinary team to read the contents of a securely and intricately folded letter which has remained unopened for 300 years, while preserving its valuable physical evidence.

A highly sensitive X-ray microtomography scanner, developed at Queen Mary University of London's dental research labs, was used to scan a batch of unopened letters from a 17th-century postal trunk full of undelivered mail.

The senders of these letters had closed them using 'letterlocking' - the historical process of intricately folding and securing a flat sheet of paper to become its own envelope. Letterlocking was common practice for secure communication before modern envelopes came into use, and is considered to be the missing link between ancient physical communications security techniques and modern digital cryptography.

Until now these letterpackets could only be studied and read by cutting them open, often damaging the historical documents. Now the team have been able to examine the letters' contents without irrevocably damaging the systems that secured them.

Professor Graham Davis from Queen Mary University of London said: "We designed our X-ray scanner to have unprecedented sensitivity for mapping the mineral content of teeth, which is invaluable in dental research. But this high sensitivity has also made it possible to resolve certain types of ink in paper and parchment. It's incredible to think that a scanner designed to look at teeth has taken us this far."

Dr David Mills from Queen Mary University of London said: "We've been able to use our scanners to X-ray history. The scanning technology is similar to medical CT scanners, but using much more intense X-rays which allow us to see the minute traces of metal in the ink used to write these letters. The rest of the team were then able to take our scan images and turn them into letters they could open virtually and read for the first time in over 300 years."

This process revealed the contents of a letter dated July 31, 1697. It contains a request from Jacques Sennacques to his cousin Pierre Le Pers, a French merchant in The Hague, for a certified copy of a death notice of one Daniel Le Pers (full transcript and images available). The letter gives a fascinating insight into the lives and concerns of ordinary people in a tumultuous period of European history, when correspondence networks held families, communities, and commerce together over vast distances.

Following the X-ray microtomography scanning of the letter packets, the international team then applied computational algorithms to the scan images to identify and separate the different layers of the folded letter and 'virtually unfold' it.

The authors suggest that the virtual unfolding method, and categorisation of folding techniques, could help researchers to understand this historical version of physical cryptography, while at the same time conserving their cultural heritage.

"This algorithm takes us right into the heart of a locked letter," the research team explains. "Sometimes the past resists scrutiny. We could simply have cut these letters open, but instead we took the time to study them for their hidden, secret, and inaccessible qualities. We've learned that letters can be a lot more revealing when they are left unopened. Using virtual unfolding to read an intimate story that has never seen the light of day - and never even reached its recipient - is truly extraordinary."