Brain

New work shows how using next-generation DNA sequencing on ancient packrat middens--nests made out of plant material, fragments of insects, bones, fecal matter, and urine--could provide ecological snapshots of Earth's past. Published today in the journal Ecology and Evolution, the study may pave the way for scientists to better understand how plant communities--and possibly animals, bacteria, and fungi as well--will respond to human-caused climate change.

"Rodent middens are powerful tools in paleoecology," said Michael Tessler, a postdoctoral fellow at the American Museum of Natural History. "We wanted to see how we could take this invaluable resource and expand its use to give us a big-picture view of what life in the Americas was like 1,000, 10,000, or even 30,000 years ago, and measure how it has changed in the time since then."

Packrats (Neotoma spp.) are long-tailed nocturnal rodents that create nests out of plant materials in dry caves and crevices. Their sticky, viscous urine helps the nests to bind together into a solid mass, capable of being preserved for tens of thousands of years--some nests even date to beyond the last ice age. These plant-rich deposits--called middens, which also can contain insects, bones, and other materials the packrats habitually collect--are found in arid parts of North America. Because the foraging range of these small rodents is limited, the contents of packrat middens represent the local environment at the time the material was gathered, providing clues about past climates and environments. Since 1960, more than 2,000 ancient packrat middens from western North America have been analyzed for fossil contents and archived.

"Midden contents are so well preserved that fragments of ancient DNA can be extracted and analyzed across millennia," said Rob Harbert, an assistant professor at Stonehill College who conceived of this study when he was a postdoc at the Museum. "They have been used to identify an extinct ground sloth preserved in southern Argentina, tell us about the history of bighorn sheep in California, and provided evidence of papillomavirus infection in packrats over the last 27,000 years. Because of their dense distribution, fossil middens in the Americas offer the chance to genetically profile entire communities through time and space, but first, we need to improve the way we analyze data from these deposits--the principal aim of this study."

The researchers analyzed ancient DNA from 25 packrat midden samples between 300 and 48,000 years old from the North American Packrat Midden Collection at the University of Arizona's Tree Ring Laboratory. The samples come from two locations: City of Rocks National Reserve in south-central Idaho, and Guadalupe Canyon in Northern Baja California, Mexico. These two sites span the range of current climatic conditions across which North American packrat middens are preserved and have been studied.

The researchers explored the use of two next-generation sequencing techniques to compare the DNA: amplicon, during which the same gene is sequenced from every sample, and shotgun, which randomly selects DNA fragments to sequence. They decided to focus on the shotgun technique for this study, finding that packrat middens up to 32,000 years old contain recoverable DNA that is consistent with fossils found in these deposits. As expected, a large portion of this DNA is bacterial, but between 20-40 percent is classified as belonging to eukaryotic organisms--those whose cells have a nucleus--including plants like grasses, pines, junipers, daisies, and roses, as well as a small number of vertebrates, including insects and fungi. Viruses were also present in small quantities.

Although this study underscores the promise of deep DNA sequencing to illuminate previous ecosystems, a great deal of progress is required to make the work more accurate. Since shotgun sequences random fragments of DNA, it requires researchers to have a strong database they can use to match the sequences to an organism. If the data for that organism do not exist, scientists only get the closest match, or no match at all. Because of this, and DNA degradation, the researchers say that they were only able to definitively match the DNA fragments to the family level and were unable to match it to genus or species groupings.

"As the costs of DNA sequencing continue to decrease and computational power increases, the prospects for using this technique will greatly improve," Harbert said. "Further investigation into the taxonomic composition of middens could refine our understanding of the timeline of past climate change, species migration, and extinction, and this will better inform the study of the effects of current and future climate change."

LA JOLLA, CALIF. - Feb. 20, 2020 - Scientists at Sanford Burnham Prebys Medical Discovery Institute and Harvard University have discovered that mitochondria trigger senescence, the sleep-like state of aged cells, through communication with the cell's nucleus--and identified an FDA-approved drug that helped suppress the damaging effects of the condition in cells and mice. The discovery, published in Genes & Development, could lead to treatments that promote healthy aging or prevent age-associated diseases such as cancer, Alzheimer's disease, heart disease and more.

"Our findings provide a foundation upon which we can start to develop drugs that extend our health span--the number of years we live a healthy life," says Peter Adams, Ph.D., a professor in Sanford Burnham Prebys' National Cancer Institute (NCI)-designated Cancer Center and senior author of the study. "Given the major social and economic hurdles we will soon face as millions of Americans grow older, interventions can't come soon enough."

The number of Americans who are age 65 or older is projected to double to more than 90 million in 2060, translating to nearly 25% of the population, due to the natural aging of the Baby Boomer generation. Today, approximately 80% of older adults have at least two chronic diseases, such as heart disease, cancer, stroke or diabetes. This trend creates a need to solve the projected onslaught of health problems we face and is fueling scientists to dive into the molecular causes of aging and find medicines that help people live long, healthy lives.

"To cope with the rise of chronic diseases from an aging population, we must understand the fundamental biological effects of aging," says Mark R. Collins, president and director of the Glenn Foundation, which partially funded the research. "These findings provide insights that bring us closer to treatment(s) that could prevent or delay the onset of many age-related diseases."

Connecting the dots

For more than a decade, Adams has studied how clusters of chromatin--the mix of DNA and protein normally found in the cell nucleus--leak out to the cytoplasm in senescent cells, triggering inflammatory signals that can promote a number of undesirable health conditions. In this study, his team set out to find what prompts the formation of chromatin clusters in the first place.

To answer this question, the scientists embarked on a series of experiments using a human lung cell model of senescence. They found that mitochondria were the culprits driving the formation of pro-inflammatory cytoplastic chromatin and did so through a retrograde communication path to the nucleus.

"In school we learned that the role of mitochondria is to generate energy--and that DNA controls everything the cell does," says Adams. "Research is now showing that mitochondria are important sensors for the cell and have a lot of cross-talk with the nucleus, which makes sense given their duty to respond to the cell's metabolic needs."

The scientists also found that an HDAC inhibitor, an FDA-approved drug currently used to treat certain cancers, transformed senescent cells from a large and flat form to a healthier and more visually youthful condition. The HDAC inhibitor-treated cells also had better mitochondrial function, less cytoplasmic chromatin and produced less inflammatory signals. The scientists observed similar beneficial effects when examining the livers of mice in which senescence was induced through radiation or high doses of acetaminophen. However, the side effects of HDAC inhibitors--which include fatigue, nausea and more--make the drugs too toxic for use in preventing disease in healthy individuals.

As a next step, the scientists hope to screen for less toxic senescence-inhibiting drugs at the Institute's Conrad Prebys Center for Chemical Genomics. For example, a compound that interrupts the communication between the mitochondria and the nucleus would hold promise as a treatment that promotes healthy aging.

"This study provides the first concrete link between several known hallmarks of aging--dysfunctional mitochondria, inflammation and senescent cells--which historically were studied as separate events," says Adams. "We are hopeful that targeting the molecular drivers of senescence will lead us to safe and effective medicines that help more people stay as healthy as possible, for as long as possible."

LOS ANGELES, Feb. 20, 2020 -- A brain stent appears safe and effective for reducing the risk of recurrent stroke in patients with cholesterol-clogged brain arteries, according to late breaking science presented today at the American Stroke Association's International Stroke Conference 2020. The conference, Feb. 19-21 in Los Angeles, is a world premier meeting for researchers and clinicians dedicated to the science of stroke and brain health.

A previous study, the WEAVE trial, showed a low 2.6% stroke and death rate within the first few days of the procedure in patients received the Wingspan stent for intracranial atherosclerotic disease. The current study yielded a long-term 8.5% total one-year stroke and death rate.

"This trial is unique because prior studies included off-label patients. This is the largest intracranial stent trial for atherosclerotic disease performed according to the FDA indication for the Wingspan stent," said Michael J. Alexander, M.D., professor and vice chairman of neurosurgery at Cedars-Sinai Medical Center in Los Angeles. "The stroke and death rates were substantially lower than the one-year rate of 20% in the stenting arm of the SAMMPRIS trial and slightly better than the 12.2% stroke and death rate in the medical arm of SAMMPRIS."

The current study - Wingspan One-year Vascular Imaging, Events and Neurologic Outcomes, known as WOVEN - is the largest on-label, intracranial stenting trial to-date with long-term follow-up. Intracranial stents are mesh tubes that act as permanent implants to open clogged brain arteries, which improve blood in flow to the brain.

WOVEN - conducted at 16 U.S. centers - followed 152 patients who were treated with the self-expanding Wingspan stent from the WEAVE trial according to the FDA guidelines for use. Data on subsequent strokes and deaths were collected, and follow-up imaging assessed possible reclogging of the stent.

"The long-term results of the WOVEN study are important to determine if safer stenting practices and lower complication rates from the treatment itself resulted in improved patient outcomes at one-year," Alexander said. "Intracranial stenting could provide an alternative

when medical therapy and other treatments have been unsuccessful."

These results will likely lead to a randomized clinical trial comparing intracranial stenting to medical therapy alone.

Researchers at the Faculty of Physics at the University of Warsaw, with colleagues from Poland and China used liquid crystal elastomer technology to demonstrate a rotary micromotor powered with light. The 5-millimeter diameter ring, driven and controlled by a laser beam, can rotate and perform work, e.g. by rotating another element installed on the same axis.

Rotational movement in nature is very rare, while at the same time ubiquitous in our civilization. While we can build a variety of rotary motors, they usually consist of many elements and it makes their miniaturization difficult. However, there is a group of materials that enable construction of small, moving and/or mobile devices - liquid crystal elastomers (LCE). Research on these materials focuses mainly on design of LCE shape and its change upon laser illumination (e.g. shrinking, bending).

Liquid crystal elastomers are smart materials that can exhibit macroscopic, fast, reversible shape change under different stimuli, including illumination with visible light. They can be fabricated in various forms in the micro- and millimeter scales and, by the molecular orientation engineering, they can perform complex modes of actuation.

Researcher from the University of Warsaw with colleagues from the Department of Mathematical Sciences at Xi'an Jiaotong-Liverpool University in Suzhou, China, Institute of Applied Physics at Military University of Technology in Warsaw, and Centre of Polymer and Carbon Materials of Polish Academy of Science in Zabrze, Poland, have now developed a micromotor that rotates thanks to the traveling deformation of the soft material, caused by the laser beam and its interaction with the ground. The main part - the rotor is a 5 millimeter ring. Appropriate design of the orientation of the elastomer molecules provides stable performance of the micromotor or can increase the rotation speed.

- Despite low speed, around one rotation per minute, our motor allows us to look at the micromechanics of intelligent soft materials from a different perspective and gives food for thought when it comes to their potential use - says Dr. Klaudia Dradrach from the Photonic Nanostructure Facility. - The motor design has been inspired by ring piezoelectric motors, often found in autofocus mechanisms of photographic lenses. The contribution of scientists from the Polish Academy of Sciences in Zabrze and the Military University of Technology was crucial to the development of the method of reproducible fabrication of LCE miniature components. Notably, young researchers took part in the study, including Mikolaj Rogoz and Przemyslaw Grabowski, PhD students from the Faculty of Physics of the University of Warsaw.

Researchers who have previously demonstrated a light-powered snail robot moving like its natural relatives believe that new intelligent materials combined with advanced fabrication methods will allow them to build further miniature components and drives.

Research on soft microrobots and polymer actuators is funded by the National Science Center (Poland) within the project "Micro-scale actuators based on photo-responsive polymers", by the Polish Ministry of Science and Higher Education with "Diamentowy Grant" awarded to M. Rogoz, Ministry of National Defense (Poland) and Xi'an Jiaotong-Liverpool University funds.

Physics and Astronomy first appeared at the University of Warsaw in 1816, under the then Faculty of Philosophy. In 1825 the Astronomical Observatory was established. Currently, the Faculty of Physics' Institutes include Experimental Physics, Theoretical Physics, Geophysics, Department of Mathematical Methods and an Astronomical Observatory. Research covers almost all areas of modern physics, on scales from the quantum to the cosmological. The Faculty's research and teaching staff includes ca. 200 university teachers, of which 78 are employees with the title of professor. The Faculty of Physics, University of Warsaw, is attended by ca. 1000 students and more than 170 doctoral students.

Using mindfulness training as a cognitive enhancement tool, two new studies from University of Miami researchers show that firefighters and soldiers who participated in short-form mindfulness training programs tailored for their respective professional contexts, benefited from improved attention and resilience. These benefits, the researchers argue, better equip these professionals to manage stressors on the frontlines of their high-demand occupations.

Acknowledging the similarities faced by first responders and active-duty military service personnel in high-stress, high-demand environments, Amishi Jha, a cognitive neuroscientist and associate professor of psychology in the University's College of Arts and Sciences, built upon previous research utilizing Mindfulness-based Attention Training (MBAT)--an innovative program co-developed in 2013 by Jha and Scott L. Rogers, director of the Mindfulness in Law Program at the University of Miami School of Law .

The MBAT program was developed by Jha and Rogers for delivery to psychologically and physically healthy individuals in high-demand, time-pressed workplace environments and comprises four central themes: concentration, body awareness, open monitoring and connection.

"For firefighters, soldiers, as well as medical professionals, business leaders and many others--success matters, not only for themselves but for all they serve and lead," Jha said. "Many of our participants are highly motivated to learn how to gain a 'mental edge' so they can succeed in very demanding circumstances. In these projects, we contextualized our training to highlight why and how mindfulness training offered in the MBAT program provides tools and skills to succeed, even under Volatile, Uncertain, Complex, and Ambiguous (VUCA) circumstances."

"Is Resilience Trainable? An Initial Study Comparing Mindfulness and Relaxation Training in Firefighters," published in the journal Psychiatry Research, investigated the effectiveness of offering short-form mindfulness training to bolster firefighters' resilience--an important factor known to mitigate the damaging effects of occupational stress on the mental health of first responders.

Ekaterina Denkova, the first author on the firefighter study and research assistant professor in the Department of Psychology, together with Jha, Rogers, and post-doctoral researcher Anthony Zanesco, wanted to know if resilience is trainable. And if so, how mindfulness training, which emphasizes present moment attention and nonreactivity, might compare to a well-matched comparison program involving relaxation (i.e., visualization and progressive muscle relaxation).

Partnering with the Miami-Dade Fire Rescue Department, the researchers examined resilience, mood, and attention in 121 Miami-Dade firefighters who were assigned to one of three groups. Two groups received either mindfulness training or relaxation training, respectively, while the third received no training and served as a control group. For both training programs, Jha and Rogers consulted with Gary Gonzalez, a retired Battalion Chief from Miami-Dade Fire Rescue Department, to ensure that the programs would resonate with firefighters.

Findings from the firefighter study include:

Psychological resilience showed a greater increase over time in firefighters who received a four-week mindfulness training compared to those who received relaxation training, or no training at all.

Self-reported positive mood and objective attentional performance also showed a greater increase over the 4-week study interval in participants from the mindfulness group who spent more days per week engaging in guided mindfulness exercises.

"We have recently experienced fires in Australia unlike any we have ever encountered," said Dennis Smith, senior station officer for the Country Fire Authority in South Warrandyte, Victoria, Australia. "It has been a dangerous and exhausting season for our firefighters. Since the intensity and frequency of fires is unlikely to abate, we need better training for our readiness and recovery. The results from Dr. Jha's study give us hope. As firefighters, we can train our minds to be more attentive, positive, and resilient with mindfulness training. We can practice a proven method that will help our first responders with the unrelenting demands of this job, so we can operate at our best and focus on rebuilding our damaged communities."

A second study, "Bolstering Cognitive Resilience via Train-the-Trainer Delivery of Mindfulness Training in Applied High-Demand Settings," published in the journal Mindfulness, investigated train-the-trainer delivery of MBAT by trainers who were highly experienced in mindfulness or novices. The novice trainers were military trainers and thus, highly familiar with soldiers' professional challenges. A total of 180 active-duty soldiers from the U.S. Army were recruited to participate in the study and assigned to be in one of three groups. Two of the groups received training from the experienced or novice trainers, respectively, and the third received no training.

Jha and her team wanted to test whether mindfulness-naïve, context-familiar military trainers could successfully deliver MBAT to soldiers after being trained for just 12 weeks.

Findings include:

Intensive military field training designed to prepare soldiers for deployment can degrade cognitive capacities, such as their attention skills.

Soldiers who received MBAT from military trainers had less cognitive decline than those in the other two groups.

These results provide a cost-effective and time-efficient strategy for rapid dissemination of short-form mindfulness training to military cohorts.

"While mindfulness training is growing in popularity, accessibility to training is limited, especially for groups where the professional climate is time pressured with its own unique culture, challenges, and demands," Jha said of the train-the-trainer research approach.

The findings from both studies suggest that it is possible to improve accessibility of mindfulness training programs for such high-demand professionals.

"What we learned here is that in addition to ensuring that mindfulness training is contextualized for participants' professional lives, trainers' context familiarity is key, perhaps even more so than having extensive mindfulness expertise. We also learned that trainers can be 'trained up' to effectively deliver mindfulness training in as little as 12 weeks. Knowing this should help empower those who wish to make mindfulness training more accessible for specialized professions."

In their ongoing work, Jha, Rogers, and the university-based research team are working with military spouses who have been trained in peer-to-peer delivery of MBAT with encouraging results, Jha said.

As social beliefs and values change over time, scientists have struggled with effectively communicating the facts of their research with the public. Now, a team of researchers from the University of Missouri and the University of Colorado believe scientists can gain trust with their audience by showing their human side. The researchers say it can be as simple as using "I" and first-person narratives to help establish a personal connection with the audience.

The study was published in the journal PLOS ONE, one of the world's leading peer-reviewed journals focused on science and medicine.

Traditionally, scientists might not always consider the audience evaluating them when sharing the facts of their research, said SiSi Hu, a graduate instructor and research assistant in the Missouri School of Journalism and corresponding author on the study.

"Most of the time the public understands what the scientist is presenting to them, but each person understands in their own way," Hu said. "Therefore, there needs to be a sense of mutual understanding -- the scientist must trust the audience as much as the audience trusts the scientist with his or her message."

After completing a literature review of perceived authenticity, the team did not find any appropriate measures relating to science communication. Therefore, based on existing literature, they created a theory of perceived authenticity in science communication -- a scientist is someone with their own belief system beyond institutional affiliations, and their messaging reflects those values.

Study participants tested the theory by completing a 19-question survey on authenticity. Survey questions were based on a description of published plant science research and a group of randomly assigned narrative messages attempting to explain that research. The group of messages included a story drawn from the real-life experiences of J. Chris Pires of how he became interested in plant science. Pires is a Curators Distinguished Professor in the Division of Biological Sciences in the MU College of Arts and Science, and an investigator in the Christopher S. Bond Life Sciences Center.

Researchers found that if a scientist shares the story of the development of the origin of his or her interest in the subject through a first-person narrative -- without use of institutional affiliations -- people are more inclined to perceive him or her as authentic. Additionally, if a scientist only uses a first-person narrative, people are more inclined to perceive a scientist as authentic based on a feeling of connection.

The team also found the narrative qualities of perceived authenticity align closely with existing literature on benevolence and integrity, two personality traits that can help an audience build trust with the person delivering the message.

"We hope our findings will provide some wisdom, guidance and tools that scientists can use to enhance their communication of their research -- that is also accessible and will be trusted by the public," said Lise Saffran, director of the Master of Public Health program at the MU School of Health Professions, and lead author on the study. "People want to know the person talking to them is a human being with their own values and point of view, and that the message they share reflects those values."

At the Department for Materials of the ETH in Zurich, Pietro Gambardella and his collaborators investigate tomorrow's memory devices. They should be fast, retain data reliably for a long time and also be cheap. So-called magnetic "random access memories" (MRAM) achieve this quadrature of the circle by combining fast switching via electric currents with durable data storage in magnetic materials. A few years ago researchers could already show that a certain physical effect - the spin-orbit torque - makes particularly fast data storage possible. Now Gambardella's group, together with the R&D-centre IMEC in Belgium, managed to temporally resolve the exact dynamics of a single such storage event - and to use a few tricks to make it even faster.

Magnetising with single spins

To store data magnetically, one has to invert the direction of magnetisation of a ferromagnetic (that is, permanently magnetic) material in order to represent the information as a logic value, 0 or 1. In older technologies, such as magnetic tapes or hard drives, this is achieved through magnetic fields produced inside current-carrying coils. Modern MRAM-memories, by contrast, directly use the spins of electrons, which are magnetic, much like small compass needles, and flow directly through a magnetic layer as an electric current. In Gambardella's experiments, electrons with opposite spin directions are spatially separated by the spin-orbit interaction. This, in turn, creates an effective magnetic field, which can be used to invert the direction of magnetisation of a tiny metal dot.

"We know from earlier experiments, in which we stroboscopically scanned a single magnetic metal dot with X-rays, that the magnetisation reversal happens very fast, in about a nanosecond", says Eva Grimaldi, a post-doc in Gambardella's group. "However, those were mean values averaged over many reversal events. Now we wanted to know how exactly a single such event takes place and to show that it can work on an industry-compatible magnetic memory device."

Time resolution through a tunnel junction

To do so, the researchers replaced the isolated metal dot by a magnetic tunnel junction. Such a tunnel junction contains two magnetic layers separated by an insulation layer that is only one nanometre thick. Depending on the spin direction - along the magnetisation of the magnetic layers, or opposite to it - the electrons can tunnel through that insulating layer more or less easily. This results in an electrical resistance that depends on the alignment of the magnetization in one layer with respect to the other and thus represents "0" and "1". From the time dependence of that resistance during a reversal event, the researchers could reconstruct the exact dynamics of the process. In particular, they found that the magnetisation reversal happens in two stages: an incubation stage, during which the magnetisation stays constant, and the actual reversal stage, which lasts less than a nanosecond.

Small fluctuations

"For a fast and reliable memory device it is essential that the time fluctuations between the individual reversal events are minimized", explains Gambardella's PhD student Viola Krizakova. So, based on their data the scientists developed a strategy to make those fluctuations as small as possible. To that end, they changed the current pulses used to control the magnetisation reversal in such a way as to introduce two additional physical phenomena. The so-called spin-transfer torque as well as a short voltage pulse during the reversal stage now resulted in a reduction of the total time for the reversal event to less than 0,3 nanoseconds, with temporal fluctuations of less than 0,2 nanoseconds.

Application-ready technology

"Putting all of this together, we have found a method whereby data can be stored in magnetic tunnel junctions virtually without any error and in less than a nanosecond", says Gambardella. Moreover, the collaboration with the research centre IMEC made it possible to test the new technology directly on an industry-compatible wafer. Kevin Garello, a former post-doc from Gambardella's lab, produced the chips containing the tunnel contacts for the experiments at ETH and optimized the materials for them. In principle, the technology would, therefore, be immediately ready for use in a new generation of MRAM.

Gambardella stresses that MRAM memories are particularly interesting because, differently from conventional main memories such as SRAM or DRAM, they don't lose their information when the computer is switched off, but are still equally fast. He concedes, though, that the market for MRAM memories currently does not demand such high writing speeds since other technical bottlenecks such as power losses caused by large switching currents limit the access times. In the meantime, he and his co-workers are already planning further improvements: they want to shrink the tunnel junctions and use different materials that use current more efficiently.

Coherence in quantum dynamics is at the heart of fascinating phenomena beyond the realm of classical physics, such as quantum interference effects, entanglement production and geometric phases.

Quantum processes of inherent dynamical nature defy a description in terms of an equilibrium statistical physics ensemble. Up to now, to identify general principles behind the underlying unitary quantum dynamics which preserve quantum coherence remains a key challenge.

Quantum walks provide a powerful and flexible platform to experimentally realize and probe coherent quantum time evolution far from thermal equilibrium. As opposed to classical random walks, quantum walks are characterized by quantum superpositions of amplitudes rather than classical probability distributions. This genuine quantum character has already been harnessed in various fields of physics, ranging from the design of efficient algorithms in quantum information processing, observation of correlated dynamics and Anderson localization, to the realization of exotic physical phenomena in the context topological phases.

While the topological order can be retrieved in the real space, accessing the full complex amplitude information characterizing the coherent superposition remains as one of the key challenges in quantum walk experiments.

In a new paper published in Light Science & Application, scientists from the CAS Key Laboratory of Quantum Information, University of Science and Technology of China, the Max-Planck-Institut für Physik komplexer Systeme, Germany, Institute of Theoretical Physics, Technische Universität Dresden, Germany, and co-workers reported on the direct observation of a dynamical topological order parameter (DTOP) that provides a dynamical characterization of quantum walks.

To this end, they realized a split-step quantum walk in a photonic system using the framework of time multiplexing. Using a previously developed technique, they achieved full state tomography of the time-evolved quantum state for up to 10 complete time steps. Importantly, this provided the full complex amplitude information of the quantum walk state.

"This is essential for our central goal of a dynamical classification of the quantum walk using the DTOP, since the DTOP measures the phase winding number ω_D (t) in momentum-space, namely of the so called Pancharatnam geometric phase (PGP)".

From the experimental results, they found that dynamical transitions between topologically distinct classes of quantum walks can be uniquely distinguished by the observed time-dependent behavior of ω_D (t).

"For a quench between two systems with the same topological character, we find ω_D (t)=0 for all time steps; instead, for a quench between two topologically different systems, ω_D (t) also starts at ω_D (t=0)=0, but monotonously changes its value at certain critical times" they added.

Generalizing these observations, they further established a unique relation between the behavior of ω_D (t) and the change over a parameter quench in the topological properties of an effective Floquet Hamiltonian that stroboscopically describes the quantum walk.

"In this way we provide a nonequilibrium perspective onto quantum walks, which can be understood as a starting point towards approaching time-dependent processes from an inherently dynamical angle that goes beyond the notion of equilibrium statistical physics. With this and the mapping onto quenches in an equivalent quantum many-body system, our experiment offers a versatile platform to study coherent nonequilibrium dynamics of many paradigmatic models such as the Su-Schrieffer-Heeger model, the p-wave Kitaev chain, or the transverse field Ising model in the future." the scientists forecast.

PHILADELPHIA, Pa.--February 18, 2020 --A strong majority of Americans agree that organ and tissue donation for research contributes to health and medical breakthroughs and acknowledge significant shortfalls for donation. This is according to a new survey released today commissioned by Research!America in partnership with The National Disease Research Interchange (NDRI).

The survey finds that most Americans (93%) agree that donated organs and tissues help researchers make scientific breakthroughs. Similarly, respondents have tremendous support for organ and tissue donation for transplant at death (85%) as well as donation for research at death (84%). More than four out of five respondents (81%) acknowledge significant shortages of both organs and tissues available for transplant and research. Continued public outreach to encourage individuals to become donors was identified by respondents as important. Despite the widespread support for organ and tissue donation for research and transplant, and recognition of shortages, slightly more than half of respondents (55%) say they are registered organ or tissue donors.

The survey finds that for those who are not registered donors, nearly half are undecided (22%) or do not have a reason (29%) for not wanting their organs to be donated for research upon death.

"The gifts of organ and tissue donations are selfless acts of generosity that provide opportunities to advance discovery, improve health, and save lives," said Bill Leinweber, President and CEO of NDRI. "For forty years, NDRI has been a world leader in the procurement and distribution of organs and tissues for research across the full spectrum of disease and disorders. Knowing that the public values this research and wants us to continue to do more of it means that we have to tell more of our story."

Some 500 scientists from across the globe are served with human biospecimens each year by NDRI. Mary J.C. Hendrix, PhD, Chair of the NDRI Board of Directors and President of Shepherd University noted, "Millions of patients with diseases such as diabetes, HIV, and cystic fibrosis are alive today as a result of therapies derived from research utilizing human organs and tissue. NDRI is committed to meeting emerging needs of the scientific community and has demonstrated tremendous value in providing organ and tissue samples to support research on a variety of initiatives, including autism spectrum disorder, traumatic brain injury, opioid addiction, Alzheimer's disease, and arthritis."

Additional highlights from the Research!America/NDRI survey include:

A total of 91% of those surveyed had heard of organ and tissue donation, and 88% of respondents had heard of donating organs and tissues for research. However, only 63% of respondents have sought information about organ and tissue donation from any source.

African-American, Asian-American, and Hispanic-American respondents were somewhat less likely than Caucasian respondents to support organ and tissue donation for transplant and research at death and are less likely to report being registered as organ or tissue donors.

Respondents admire those who donate organ and tissue for transplant (77% saying 'a great deal') as well as those who donate organ and tissue for research (71% saying 'a great deal').

Most respondents (79%) are comfortable with their donated organs and tissue being used in research by a nonprofit, but fewer (57%) are comfortable with their donated organ and tissue being used in research by a for-profit organization.

"Consistent with other surveys we've commissioned on other topics, the public tells us they place a high value on medical research," said Research!America President and CEO Mary Woolley. "Americans believe in the hope research presents to improve the health and well-being of individuals, families, and communities. Organ and tissue research offer a unique opportunity to drive innovative discoveries and find solutions to what ails us."

NDRI is a 24/7 operation that partners with a nationwide network of over 130 tissue source sites (TSS), including organ procurement organizations (OPOs), tissue banks, eye banks, and hospitals. Throughout NDRI's 40-year history, the organization has worked tirelessly to provide researchers with organs, cells, and tissues to advance research toward treatments and cures to improve the lives of patients and their families.

Howard Nathan, NDRI Board Member and President and CEO of Gift of Life of Philadelphia, a leading OPO that has worked with NDRI since its founding, shared, "Thanks to the selflessness and generosity of donors and their families, groundbreaking science and community support, our nation leads the world in donation, transplantation and research. Yet this poll shows that with education and outreach we can do even more to ensure that no one dies waiting for a transplant and to enable researchers to find cures for so many disabling and deadly diseases. We are proud of our partnership with NDRI and to be able to offer families the legacy of advancing science and medical care through donation."

Irvine, Calif. February 18, 2020 - Low oxygen levels in the heart have long been known to produce life-threatening arrhythmias, even sudden death. Until now, it was not clear how.

New findings, in a study led by Steve A. N. Goldstein, MD, PhD, vice chancellor for Health Affairs at the University of California, Irvine, and distinguished professor in the UCI School of Medicine Departments of Pediatrics and Physiology & Biophysics, reveal the underlying mechanism for this dangerous heart disorder.

"Our research shows that within seconds, at low levels of oxygen (hypoxia), a protein called small ubiquitin-like modifier (SUMO) is linked to the inside of the sodium channels which are responsible for starting each heartbeat," said Goldstein. "And, while SUMOylated channels open as they should to start the heartbeat, they re-open when they should be closed. The result is abnormal sodium currents that predispose to dangerous cardiac rhythms."

Titled, "Hypoxia produces pro-arrhythmic late sodium current in cardiac myocytes by SUMOylation of NaV1.5 channels," the study was published today in Cell Reports. Lead author, Leigh D. Plant, PhD, assistant professor at the Bouvé College of Health Sciences, Department of Pharmaceutical Sciences at Northeastern University, was a former post-doctoral fellow with Dr. Goldstein.

Every heartbeat begins when sodium channels open and ions to rush into heart cells--this starts the action potential that causes the heart muscle to contract. When functioning normally, the sodium channels close quickly after opening and stay closed. Thereafter, potassium channels open, ions leave the heart cells, and the action potential ends in a timely fashion, so the muscle can relax in preparation for the next beat. If sodium channels re-open and produce late sodium currents, as observed in this study with low oxygen levels, the action potential is prolonged and new electrical activity can begin before the heart has recovered risking dangerous, disorganized rhythms.

Fifteen years ago, the Goldstein group reported SUMO regulation of ion channels at the surface of cells, an unexpected finding since the SUMO pathway had been thought to operate solely to control gene expression in the nucleus.

"This new research shows how rapid SUMOylation of cell surface cardiac sodium channels causes late sodium current in response to hypoxia, a challenge that confronts many people with heart disease," said Goldstein. "Previously, the danger of late sodium current was recognized in patients with rare, inherited mutations of sodium channels that cause cardiac Long QT syndrome, and to result from a common polymorphism in the channel we identified in a subset of babies with sudden infant death syndrome (SIDS)."

The information, gained through the current study, offers new targets for therapeutics to prevent late current and arrhythmia associated with heart attacks, chronic heart failure and other life-threatening low oxygen cardiac conditions.

A comparison of the strengths and challenges of primary care between hospital-based practices and community-based office practices was observed in a cross-sectional study in Japan. Each type of practice had its strengths in terms of patient experiences and challenges. Patients at community-based office practices reported better patient experiences of community orientation than those in hospital-based practices. Hospital-based practices were associated with better patient experience of first contact, compared with office-based practices. Six small and medium-sized hospitals and 19 community-based office practices participated in the study of 1,725 patients. Patient experience was measured using a Japanese version of the Primary Care Assessment Tool, which was comprised of first contact, longitudinality, coordination, comprehensiveness (services provided), and community orientation. Understanding the strengths of each practice type with respect to patient experience may inform future efforts to improve the patient experience overall.

Genetic mechanisms that govern brain plasticity - the brain's ability to change and adapt - have been uncovered by researchers at the University of Birmingham.

The work was carried out using the fruit-fly Drosophila, an important organism in neuroscience because it enables researchers to study an entire nervous system. That means genes can be identified and linked all the way from to specific neurons, to neural circuits, brain structure and behaviour.

This fundamental research could pave the way to a deeper understanding of how the human brain adapts over time, and the links between plasticity and neurodegeneration.

Scientists have known for some time that human brains are adaptable and plastic. For example, our brains change as we learn new things, or enable us to adapt and compensate after an amputation or if part of our brain becomes damaged. The mechanisms behind this plasticity, however, are not well understood.

In a new study, published in the journal eLife on 18 February 2020, researchers in the University of Birmingham's School of Biosciences have identified a particular set of genes that regulate brain plasticity.

The genes encode proteins called Toll receptors - responsible for receiving and transmitting signals within cells. Tolls are known to play a central role in the body's immune system, but the Birmingham team, led by Professor Alicia Hidalgo, had shown that they also influence nervous system formation. Now, linking Tolls to brain plasticity is a further significant and surprising development.

Professor Hidalgo explains: "The specific molecules we identified are well known for the role they play in regulating the body's immune system. Perhaps in evolution the nervous system and the immune system shared a common origin, as they share similar functions - for example, the immune system helps to protect us from microbes, while our nervous system through behaviour plays a role in protecting us from larger dangers, like reacting to threats. And it seems that brain plasticity re-activates the mechanisms that operate during the formation of the brain in development."

The researchers found that the Toll receptors, of which there are 9 in the Drosophila brain and 11 in the human brain, are present across different areas of the brain dedicated to different functions. From here they regulate neuronal number and brain size.

"This arrangement of the Tolls suggests they can work independently of each other, perhaps to control the response to different sensory stimuli such as smell, or vision," says Professor Hidalgo. "These can then be modulated to influence the formation and maintenance of particular types of neurons in response to experience."

It is not yet known how closely these mechanisms, identified in Drosophila will match those in the human brain, but the work gives us important clues into what to look for in the human brain to understand brain plasticity.

"Drosophila is a powerful model organism because we can show that brain plasticity has a genetic basis and identify how genes control this process," says Professor Hidalgo. "This gives us a really useful set of clues and insights into the molecular mechanisms of plasticity also in human brains."

Oxidative stress affects all living organisms, and the damage it causes is believed to play a part in cancer, diabetes, Alzheimer's disease and a number of other health conditions. Some animals have developed remarkable, even radical strategies for combating its effects. Researchers at EPFL observed that, under acute oxidative stress, flies belonging to the genus Drosophila, commonly known as fruit flies, remove and excrete damage-causing lipids, or fats, from their blood. The team has published its findings in the journal Immunity.

Like humans, fruit flies produce molecules known as reactive oxygen species (ROS), a group that includes free radicals. Although they tend to get a bad press for the harm they cause to our cells, these molecules also have beneficial effects, for instance alerting the immune system to an infection or repairing damaged tissue.

In normal circumstances, their harmful effects are counteracted by our cells' natural defense mechanisms, and by antioxidants such as vitamins C and E. Yet pathogens, smoking and ultraviolet light can upset this delicate balance by sending ROS production into overdrive, eventually overwhelming our body's natural defenses.

Dropping like flies

The EPFL team, led by Professor Bruno Lemaitre, happened upon a previously unknown defense strategy against ROS in fruit flies after observing that mutant individuals grown in the lab were dying a few days after exposure to a normally benign pathogen.

An initial investigation revealed the reason: fruit flies normally produce a fat-binding protein in their kidneys, but a mutated gene was depriving the genetically altered flies of this capability.

"Because the flies were dropping fast, we decided to have a bit of fun," says Prof. Lemaitre. "We named the mutated gene and the protein after Marco Materazzi, the Italian soccer player on the receiving end of Zinedine Zidane's infamous headbutt in the World Cup final."

A previously unknown mechanism

At this point, the team still hadn't made the link between the flies' death, the genetic mutation and oxidative stress. "We were baffled by what we discovered," explains Prof. Lemaitre. "Why were insects under pathogen-induced stress dying because they couldn't produce a fat-binding protein in their kidneys?"

The answer lies in a secondary mechanism of oxidative stress, by which free radicals attack lipids in the blood, producing toxic compounds and even more ROS. This self-perpetuating process, known as lipid peroxidation, has to be brought under control at all costs.

Fruit flies have a simple yet effective way of stopping this process from spiraling out of control: they remove one part of the equation altogether. Certain stressors cause the fly's kidneys to begin producing the Materazzi protein, which binds to the lipids in its blood. These are then passed out in the insect's feces.

"As we saw with our mutants, this mechanism really is a matter of life and death for a stressed insect," says Xiaoxue Li, a scientist in Prof. Lemaitre's group and the paper's lead author.

The scientists suspect this same mechanism could play an important role in other insects, and perhaps even in other animals. Previous studies have identified an allergen in cockroach droppings that bears many similarities to the Materazzi protein.

"Just like the flies in our study, all living organisms have to deal with oxidative stress damage," adds Prof. Lemaitre. "I wouldn't be surprised to see it become a major public health issue."

Inexpensive near-to-mid infrared (IR) sources and detectors operating at room temperature (rather than cooled to low or even cryogenic temperatures) are expected to revolutionize current technologies for the realization of various night vision and security systems, sensing and spectroscopy tools, etc. Colloidal semiconductor quantum dots (QDs) characterized by a high photoluminescence quantum yield (PL QY), which reaches up to at least 40% in the near to short wavelength IR (1-2 μm) range nowadays, represent a promising material for the realization of these devices. Unfortunately, at longer wavelengths, further into the IR, the PL QY rapidly drops as the radiative emission rate decreases following a basic rule of physics termed Fermi's Golden Rule, and non-radiative recombination channels compete more effectively with the light emission process. So, the brightness of the PL emission is hard to maintain at longer IR wavelengths. To achieve the ultimate performance of such devices it is important to control the emission properties of the QDs, providing a means of restoring the chances of radiative emission over non-radiative recombination.

In a recent paper published in Light Science & Application, scientists from the Department of Materials Science and Engineering, and Centre for Functional Photonics (CFP) of City University of Hong Kong; Institute of Automation and Control Processes of Far Eastern Branch of Russian Academy of Sciences; Far Eastern Federal University; University of Technology Sydney; Engineering Research Center of Nano-Geomaterials of Ministry of Education of China University of Geosciences; Department of Electronic Engineering of The Chinese University of Hong Kong; and Swinburne University of Technology, developed ordered arrays of plasmonic nanoantennas which can resonantly interact with a pump radiation beam used to excite the IR QDs and significantly tailor the spontaneous radiative emission rates, the lifetime of an excited state, and the resulting emission spectrum of the IR-emitting HgTe QDs in a broad spectral range up to 3 μm (a limit set by current array patterning and the strength of the interaction with the excitation light). This interaction modifies the emission rate and helps to offset the proportion of the excitation that is lost to competing non-emissive recombination processes.

The novel plasmonic platform, the nanobump array, contains millions of properly arranged conical-shape nanobumps, which were fabricated via direct processing of an Au film with fs laser pulses. The developed fabrication approach is reproducible (in terms of the nanobump shape variations and spacings), inexpensive and easily scalable to process squared centimeter areas, opening a pathway for realistic applications and devices. The plasmonic structure arrangement used supports both localized and lattice-type surface plasmon resonances (both types are useful), which were shown to efficiently tailor and enhance the emission properties of a thin capping layer of IR-emitting HgTe QDs. The reported results open new avenues for precise tuning of the IR-emitting QDs' emission which are expected to improve the performance of various types of IR devices.

Scientists have summarized the key points of their study as follows:

"We experimentally demonstrated the ability to boost and tailor the spontaneous near-to-mid IR emission of HgTe quantum dots via their coupling to Au plasmonic arrays. In particular, we have achieved a 5-fold enhancement of the PL quantum yield and reduced the proportion of non-radiative PL decay from a HgTe QD layer capping a laser-printed nanobump array, where different plasmonic resonances of the Au structure were appropriately matched to the emission and absorption bands of the attached QD emitters."

"Considering the ease of the chemical synthesis and processing of the HgTe QDs combined with the scalability of the direct laser fabrication of nanoantennas with tailored plasmonic responses, our results provide an important step towards the design of IR-range devices for various applications. The combination of the QDs with nanoplasmonic substrates enhances the IR performance and combats a fundamental physics limitation imposed on the QDs when operating in isolation."

"The other important result is that we can also overcome the negative absorption dips in a PL spectrum arising from IR vibration bands of the organic ligand used to stabilize the QDs. Such ligand vibration overtone and combination bands can couple strongly with the QD excitons directly via a trapped charge/vibrational mode quasi particle mediated transfer mechanism and provide an unwelcome but efficient non-radiative decay channel. We showed that matching the first-order lattice resonance of the nanobump array with a vibration band of the stabilizing ligand decreases the degree of non-radiative decay (by allowing radiative recombination to occur more rapidly than the unwanted non-radiative process) in this spectral range providing a smooth nearly Gaussian-shaped spectrum without the coupling dip."

Scientists at Tokyo Institute of Technology (Tokyo Tech) demonstrate the first visible-light photoelectrochemical system for water splitting using TiO2 enhanced with an earth-abundant material - cobalt. The proposed approach is simple and represents a stepping stone in the quest to achieve affordable water splitting to produce hydrogen, a clean alternative to fossil fuel.

Photoelectrochemical water splitting, the process by which light energy is used to split water molecules into hydrogen (H2) and oxygen (O2), is a promising approach to obtain pure hydrogen for use as an alternative clean fuel. This process is carried out in electrochemical cells that contain an anode and a cathode submerged in water, which are connected through an external circuit.

At the anode, water oxidation occurs, whereby O2 is produced by drawing energy from light waves. These waves transfer energy to the electrons of the anode material, allowing them to move through the external circuit to reach the cathode. Here, the received electrons and the cathode material cause H2 to form.

To date, it has been difficult to find photoelectrochemical systems that carry this process efficiently due to various reasons. Titanium dioxide (TiO2), a well-known and widely used photoanode material, can only absorb energy from light in the ultraviolet region; that is, high-energy light. Because it would be preferable to leverage the energy from longer-wavelength light, TiO2 can be mixed with noble metals (such as gold or silver) to sensitize it to visible light, but this would be expensive in large-scale applications.

To find a solution to this problem, a research team from Tokyo Tech created the first visible-light photoanode made of TiO2 enhanced with an earth-abundant material - cobalt. Their study published in ACS Applied Materials & Interfaces explains the surprisingly simple process of photoanode fabrication; thin TiO2 films are grown onto a substrate through a standard procedure and then cobalt is introduced by immersing them into an aqueous cobalt nitrate solution. "This study demonstrates that a visible light-driven photoelectrochemical cell for water oxidation can be constructed through the use of earth-abundant metals without the need for complicated preparation procedures," remarks Prof. Kazuhiko Maeda, who led the research.

Through multiple types of spectrometry analyses and scanning electron microscopy, the researchers identified the specific composition and structure of the cobalt-modified surface of the TiO2 photoanode to understand how cobalt allows the material to absorb visible light to mobilize electrons and cause water oxidation. It turns out that cobalt domains not only capture visible light and transfer charges (electrons) at the TiO2 interface, but also serve as catalytic sites that facilitate water oxidation. Moreover, the researchers found that the structure of the base TiO2 thin film affects the performance of the final modified photoanode, presumably by allowing for a better or worse accommodation of cobalt atoms. The structure of the TiO2 film can be easily tuned by adjusting fabrication parameters, which allowed the team to carry out multiple tests to gain insight on this phenomenon.

More work still needs to be done, as it will be necessary to further optimize the design of the photoanode to improve the charge transfer process that occurs between the cobalt atoms and the TiO2 substrate to achieve higher water oxidation rates. Nevertheless, a major advantage of the proposed water oxidation system is that it is non-sacrificial; in other words, the materials employed do not rely on energy-rich oxidants and/or reductants (i.e., sacrificial reagents). "So far, cobalt-sensitized water photooxidation systems had been comprised of powder-based photocatalysis, which work only in the presence of a sacrificial electron acceptor. Therefore, the present study also demonstrates sacrificial reagent-free visible-light water splitting using a cobalt-sensitized semiconductor material (TiO2)," concludes Prof. Maeda. This study will hopefully serve as a stepping stone for all those trying to achieve affordable water splitting to ensure a greener future.