Culture

ITHACA, N.Y. - House finches are locked in a deadly cycle of immunity and new strains of bacterial infection in battling an eye disease that halved their population when it first emerged 25 years ago, according to new research from the Cornell Lab of Ornithology.

House finch eye disease causes red, swollen, watery or crusty eyes. Afflicted birds can recover, but may die because they cannot see well enough to find food or avoid predators. The latest analyses, based on the observations of Project FeederWatch participants from eight Northeast states, addresses the long-term impact of the disease on house finch populations and points to the role of the finch immune system in the bird vs. bacteria battle.

"We have an escalating arms race," said Cornell Lab researcher Wesley Hochachka, first author of "Host Population Dynamics in the Face of an Evolving Pathogen," which published April 5 in the Journal of Animal Ecology. "Finches who become infected but survive acquire some immunity to that version of the bacteria and its predecessors. The bacteria evolve to get around the strengthened finch immunity. Then birds acquire immunity to the latest strain, and the cycle keeps repeating.

The study's authors believe that acquired immunity - when the immune system creates antibodies in response to an infection - is actually driving the arms race between the birds and the bacteria. They said imperfect acquired immunity, just like imperfect vaccines against human pathogens, creates the conditions needed to favor the proliferation of new strains of the bacteria that can overcome immunity acquired against existing strains of bacteria.

Immunity can also develop through genetic changes to the house finches, but this would be a relatively slow process, requiring multiple years for genetically novel and resistant finches to become widespread. In contrast, genetic changes to the bacteria can proliferate within hours - so fast that populations of house finches can't possibly evolve a defense quickly enough.

"We should really pay more attention to the role that acquired immunity can play in the dynamics of disease in any animal," Hochachka said. "Interactions can be much more complicated when both the host and the disease are able to change rapidly."

The overall house finch population was cut in half during the initial outbreak when the bacteria jumped to finches from poultry in 1994. House finch populations now are mostly stable at their current, lower level.

Hochachka said that's surprising because typically in other tracked animal diseases, either the animal populations rebound or fluctuate widely following the initial disease outbreak. But he thinks the finch population is not likely to return to pre-disease levels.

The finch eye disease dynamic has parallels to human health and the use of vaccines to give people acquired immunity to diseases. Here also, imperfect immunity - vaccines that do not provide perfect protection - are believed to accelerate the spread of new strains of pathogens against which vaccines are ineffective.

"The emergence of new diseases is going to keep happening," Hochachka said. "We just have to develop methods and systems for dealing with it as best we can when a lethal disease appears."

Evolution is unfolding in real time within many natural animal populations and researchers are now observing how this influences biodiversity in the field. In a newly published study in Molecular Ecology a team of Drexel University scientists examined the biological variations in pea aphids, insects that reproduce frequently enough to evolve before our eyes, by tracing the prevalence of their protective endosymbiont, Hamiltonella defensa, which the insects use to ward off parasitoid wasps.

"We know that certain organisms have many generations in a season, and we know sometimes it just takes a handful of generations for evolution to unfold; and aphids are one of those types of organisms," explained Jacob A. Russell, PhD, a professor in the College of Arts and Sciences, and senior author on the study.

Like many insects, aphids play host to symbiotic bacteria - or endosymbionts - in their blood and internal tissues. While their full range of impacts is not yet understood, these bacteria typically provide some defense against environmental pressures, like parasites and parasitoids - parasites that kill their hosts. Hamiltonella defensa, the endosymbiont focused on in this study, for instance, wards off parasitoids in pea aphids. But these bacteria are also of interest to researchers because they are heritable -- passed on from females to their offspring.

"In essence, these bacteria are inherited like mitochondrial DNA and because of this, they can serve as part of the pea aphid's adaptive arsenal, acting alongside the many thousands of genes in this sap-feeding insect's genome," said Russell.

Andrew Smith, PhD, a former Drexel graduate and current Rodale Institute Chief Scientist, led the research efforts that enabled the biologists to get a closer look at the natural forces shaping Hamiltonella prevalence. It was their hope that, through repeated field collections and routine molecular screening, they could shed light on the evolutionary forces affecting aphids in real time.

"We were motivated to try to understand why this one endosymbiont is maintained in these populations, why is it never lost and why it doesn't just go to 100% frequency," said Russell. "One idea is there must be some times when it helps the aphid, as well as times when it is slightly harmful."

To supplement their aphid collection and endosymbiont screening, the field team studied a range of environmental variables within the same alfalfa fields, including the prevalence of Aphidius ervi, a parasitoid wasp introduced in the United States to control populations of the pea aphid, which was once a threat to crops, including alfalfa. The wasps kill aphids by laying eggs inside them. Intriguingly, Hamiltonella endosymbionts prevents young wasp development, but they also come with a cost, according to the researchers.

"There's this 'rent' that the aphid has to pay to the endosymbiont just to sustain its populations," said Russell. "In the lab, we initially thought the aphids with the endosymbiont would be worse off than the aphids that did not have the endosymbiont due to this 'rent' concept."

This concept, that aphids with Hamiltonella endosymbionts were worse off than those without them in the absence of the wasps, was supported by prior lab experiments. But despite this expectation, the authors found no significant relationship between wasp prevalence and endosymbionts. But they did see aphid populations evolving over time - with the endosymbiont's prevalence shifting rapidly, on several occasions. Correlating most clearly with these shifts was the temperature of the aphids' surrounding environment.

Their results suggest "the cost of 'rent' is higher for aphids harboring these endosymbionts when it's cool," said Russell, who thinks "it's actually pretty useful for the aphids to have these endosymbionts when it's warm."

The authors conclude that the endosymbiont's dynamics, and hence real time evolution of the pea aphid, likely result from an evolutionary phenomenon known as "balancing selection," which happens due to changing costs and benefits of harboring the endosymbiont at different temperatures.

This would render Hamiltonella as a fair weather friend, useful when it's warm, and harmful when it's not. Though the mechanism of this seasonality remains undetermined, their results suggest that temperature could serve as a major factor in conjuring the occurrence of Hamiltonella endosymbionts in aphids.

This discovery was only possible because the team made its observations in the field. "We tend to do our lab experiments in these pretty one-dimensional lab environments and temperature is held constant," said Russell, "so those lab findings might not be fully transferable,".

This work provides one of the first examples of a study on seasonal insect adaptation that's enabled not by variation in insect genes, but by variation in their endosymbionts. As such, it is among the first to show that maternally transmitted microbes - found in most insect species - respond to the pendulum-like nature of changing environments across the seasons.

Given the longer-term trends in global climate, it is possible, too, that endosymbionts may govern the future success of insect species in our rapidly warming world.

DES PLAINES, IL - The diagnostic value of the Head-Impulse, Nystagmus, Test of Skew (HINTS) exam in the emergency department setting is limited. This is the result of a study titled Diagnostic Accuracy of the HINTS Exam in an Emergency Department: A Retrospective Chart Review, which will be published in the April issue of the Academic Emergency Medicine (AEM) journal, a peer-reviewed journal of the Society for Academic Emergency Medicine (SAEM).

The lead author of the study is Cait Dmitriew, PhD, from the department of undergraduate medicine at the Northern Ontario School of Medicine, Sudbury, Ontario, Canada.

The HINTS exam is a series of bedside ocular motor tests designed to distinguish between central and peripheral causes of dizziness in patients with continuous dizziness, nystagmus, and gait unsteadiness. The study found that HINTS exam use was high, but frequently used in patients who did not meet criteria to receive it. Most often this was because patients lacked documentation of nystagmus or described their symptoms as intermittent. In addition, many patients received both HINTS and Dix-Hallpike exams, which are intended for use in mutually exclusive patient populations. In no case was dizziness due to a central cause identified using the HINTS exam.

The results suggest that the test is of limited utility as currently used by emergency department physicians and that further training in how to identify appropriate candidates and interpret the results of the ocular motor exam may improve its diagnostic accuracy. The authors advise that additional training of emergency physicians may be required to improve test sensitivity and specificity.

A team of researchers from the Africa Climate and Development Initiative (ACDI) led a global team of 21 climate risk scholars to better understand and inform decision making around climate change risks in Africa and globally by examining how the drivers of risk interact.

Their work extends on existing risk frameworks with the hope that this research could help decision makers, managers and researchers understand the inherent complexity of climate change.

"Understanding the interactions among risks holds potential to change the way we respond to the risks. This is important because policy makers may worry about the risk of implementing a response as much, or more so, than the risk the response aims to reduce. This can lead to inaction at the very time when we need to be most active and investing heavily in our response to climate change," said Dr Nick Simpson, lead author of the paper published in One Earth, and postdoctoral fellow at the ACDI based at the University of Cape Town (UCT).

Two important responses to climate change - adaptation and mitigation - are often not considered as part of climate risk assessment. In the article, the team, extends the existing risk framework used by the Intergovernmental Panel on Climate Change (IPCC) by including response options, identifying multiple interactions of drivers of risk, and risk interactions in risk assessment.

Across the suite of terms that have been applied to climate change risk for human and natural systems, there is a commonality: an interaction or aggregation of the determinants of risk (hazard, exposure, vulnerability), and of multiple risks. The researchers expand on this by explicitly recognising that a response to climate change can also be a driver of risk as shown in the diagram.

For example, biological responses to heatwaves can create faster than normal soil moisture depletion known as a 'false spring' as a response to unusual early season growth increasing risk of wildfire and compound conditions of extreme heat (hazard), duration of heatwave (exposure) and increased fuel load (vulnerability).

Yet, response has been generally considered separately or secondarily to interactions between hazards, exposures and vulnerabilities. As a result, response is considered for how it can manage or reduce risk rather than how it might also create risk. But response should be at the centre of climate risk assessment and management.

Simpson highlighted the importance of this innovation: "If human and biological response to climate change was better integrated with conceptualisation of risk, its assessment would be more policy relevant and better reflect real-world decision making around risk," he said.

The framework goes on to identify two more categories of complex climate change risk and highlights the importance of also considering the interactions of the multiple drivers of risk and interactions between risks themselves. This is particularly important in the African context where there is unique vulnerability and exposure challenges for particular populations and is well illustrated by the interactions of risks during the Cape Town drought.

Effective responses to the drought were delayed due to the political risk of declaring a disaster and a lack of feasible water supply alternatives. Responses became increasingly urgent in early 2018 as the potential of a 'Day Zero' event became possible, the point at which a city of four million people might run out of water. The risk of 'Day Zero' was anticipated to cascade to affect risks to health, economic output and security and responses by different groups interacted to generate risks to municipal finance.

Considering interactions among these multiple risk and risk drivers is important as it shifts risk assessment from a concentration on individual climate hazards or interactions of hazards as a single 'event', such as a drought or flood, to situate that climate hazard within a set of multiple events interacting continuously with evolving social and economic conditions.

Access the full study: Simpson, N.P., et al. (2021). Assessing and responding to complex climate change risks, One Earth. DOI https://doi.org/10.1016/j.oneear.2021.03.005.

Extremist perpetrators of violence often quote verses from their religion's holy scriptures that authorize, or even prescribe, attacks on enemies of the faith. Abdullah H., the Syrian now on trial who stabbed a homosexual couple with a knife and killed a man in Dresden in October 2020, also testified that he had been inspired to commit the crime by a Quranic sura. However, whether the religious motivation that extremist perpetrators of violence emphasize is causally related to their actions is often doubted. Now, WZB researchers Ruud Koopmans and Eylem Kanol can prove for the first time that verses in religious scriptures that legitimize violence can increase support for killing enemies of the faith.

Together with Dietlind Stolle, a German-Canadian political scientist, they designed an experimental study in which they asked 8,000 Christians, Muslims, and Jews in seven countries (Germany, the United States, Cyprus, Lebanon, Israel, the Palestinian territories, and Kenya) whether or not they thought lethal violence against enemies of the faith was justified. Half of the respondents were asked the question without any introduction, while the other half were first presented with a quote from the Bible, Koran, or Torah that endorsed violence against alleged enemies of the faith.

The results show that reference to scriptural passages legitimizing violence significantly increased support for lethal violence in all three religions and in all seven countries (see graph). However, this effect was weaker among Jews and Christians than among Muslims. Across all seven countries, 9 percent of Christian believers supported violence without receiving a scriptural quote beforehand, against 12 percent among those who were given such a quote. Among Jewish believers, the figures were 3 and 7 percent, respectively. Among Muslims, 29 percent supported violence against enemies of the faith without and 47 percent with prior reference to a Quranic quote. In Germany, however, these figures were considerably lower: among German Christians, support for violence was 2 without and 3 percent with a biblical quotation; among German Muslims, 5 without and 16 percent with a Koran quotation (seeh graph).

The most important reason for the differences between the three religions, the researchers show, is the larger proportion of Muslim believers who adhere to a fundamentalist interpretation of their faith. Fundamentalist believers are characterized by the fact that they take the holy scriptures of their religion literally and consider them to be unambiguously valid in the present. Therefore, they are comparatively more susceptible to attempts to legitimize violence by referring to religious scriptural sources.

The findings have significance for countering religious extremism. "Religious causes and motivations must be taken seriously. Violence should not be reduced to socio-economic and psychological causes alone," says Ruud Koopmans, director at the WZB. The task of religious leaders and associations, he says, must be to actively counter fundamentalist interpretations of faith and to promote interpretations that take the historical and social context into consideration.

In a rare exchange, scientists and water resources engineers from Iran and Utah are collaborating on a bold scientific study to restore one of the world's largest saline lakes.

Lake Urmia -- a massive salt lake in Iran's northwest and a sister to Utah's Great Salt Lake -- has lost nearly 95 percent of its volume over the last two decades. As water levels drop, salinity spikes, threatening the lake's brine shrimp population and the flamingos and other bird species that depend on the shrimp for food. Lake levels are so low that at some coastal resorts, tourism boats must be pulled a kilometer (0.6 mile) or more from shore by tractor before reaching suitable depths. In addition, new land bridges are forming in the drying lake bed which allows mainland predators to threaten endangered mammals living in the southern islands. The vast, dry lakebed imposes a growing dust problem for the five million residents who live in the Lake Urmia basin. What's more, the area's ecotourism industry has collapsed, and now experts fear an environmental disaster awaits if drastic changes are not made.

"We're at the tipping point," said assistant professor and lead author Somayeh Sima of Tarbiat Modares University in Iran. "Every single step matters. We have to take action now." Sima's work will be used to update Iran's $1 billion Lake Urmia Restoration Program. In 2018, she traveled to Utah on a visiting scholarship from the Semnani Family Foundation to collaborate with Utah State University water resources professor David Rosenberg who studies integrated water management and water conservation in Western U.S. river basins, including rivers that feed the Great Salt Lake. Prof. Wayne Wurtsbaugh, Sarah Null, and Karin Kettenring from the USU Quinney College of Natural Resources also collaborated in the limnology and ecology parts of this multidisciplinary research.

The team synthesized 40 years of data to define eight metrics that define the health of Lake Urmia and its many ecosystems. Their findings were published in the latest edition of the Journal of Hydrology: Regional Studies. One key finding shows that setting a target water level will not necessarily solve Lake Urmia's problems.

"We can't say that restoring the lake to some magic number will improve the overall situation," said Rosenberg. "Instead, we need to consider how the lake's ecosystem services are interconnected and how a varying lake level will impact those systems over time."

"We have to embrace lake level variability and focus our restoration efforts where it makes sense," Sima added. "Restoration is not an easy task. It is everyone's responsibility, and we'll need public support to make meaningful change."

The problems facing Lake Urmia are not unique to Iran. Water levels at the Great Salt Lake are also at their lowest in recent years, and similar problems of land bridges, dust, changes in salinity, and ecological damage have experts concerned.

To promote transparency and reproducibility in science and encourage further collaborations, the researchers published their article open access (free to readers) and shared their data and code on the HydroShare.org repository.

"This partnership between U.S. and Iranian researchers is valuable because we have so much in common on this topic, said Sima. "Only together can we begin to understand how to solve these problems."

Smoking is the leading cause of preventable death in America and causes about 30% of all cancer deaths. That's why researchers with the UC Davis Comprehensive Cancer Center wanted to study the impact of a California law passed in 2016 that raised the tobacco sales age from 18 to 21. Their new study published in Preventive Medicine examines smoking behavior after the state implemented one of the first tobacco 21 (T21) policies.

The study, conducted by UC Davis researchers Melanie Dove, Susan Stewart and Elisa Tong, looked at smoking patterns before and after the law passed and compared California and other states without a T21 policy. The data was from the 2012-2019 Behavioral Risk Factor Surveillance System.

"Most adult tobacco users start smoking cigarettes before the age of 18, when the brain is still developing and is especially susceptible to nicotine and addiction," said Dove, assistant professor of UC Davis Department of Public Health Sciences, Division of Health Policy and Management and lead author of the paper. "The new T21 law has the potential, over time, of dramatically reducing the number of youth who begin smoking regularly and that's why it is important to track the impact."

The study showed that the new T21 law was associated with a greater decrease in smoking, at least when it came to daily smoking, in 18-20-year-olds compared to 21-23-year-olds in California.

"The great news is that the prevalence of 'daily' smoking among 18-20-year-olds went from 2.2% in 2016 to nearly zero in 2019," said Stewart, professor with UC Davis Department of Public Health Sciences, Division of Biostatistics. "A possible reason that we may have seen a decrease in 'daily' smoking, but not 'non-daily' smoking, is that 'daily' smokers are more likely to buy their own cigarettes--so they are more likely to be impacted by sales restrictions."

There was no decrease found in 'non-daily' smoking and that's likely because these users don't smoke regularly and often get cigarettes from a friend or family member. Additionally, there was no associated decrease in 'ever' or 'current' smoking patterns with California's T21 law, at least three years post-implementation.

While it may be surprising that the new T21 law didn't reduce cigarette smoking across all types of smoking behavior, explanations include pre-existing declines in smoking nationwide, enforcement challenges at the state level, increased use of other products (e-cigarettes and marijuana), definitions of smokers in the study, sales outside of retail stores and other tobacco control policies.

"Future studies should examine the role of e-cigarette use, policy enforcement as well as online sales," said Tong, an internist and associate professor who directs tobacco cessation initiatives at the UC Davis Comprehensive Cancer Center. "These are important public health issues that deserve examination and, potentially, new policy solutions in order to protect our youth in California from the deadly diseases that often result from addiction to tobacco products."

A breakthrough astrophysics code, named Octo-Tiger, simulates the evolution of self-gravitating and rotating systems of arbitrary geometry using adaptive mesh refinement and a new method to parallelize the code to achieve superior speeds.

This new code to model stellar collisions is more expeditious than the established code used for numerical simulations. The research came from a unique collaboration between experimental computer scientists and astrophysicists in the Louisiana State University Department of Physics & Astronomy, the LSU Center for Computation & Technology, Indiana University Kokomo and Macquarie University, Australia, culminating in over of a year of benchmark testing and scientific simulations, supported by multiple NSF grants, including one specifically designed to break the barrier between computer science and astrophysics.

"Thanks to a significant effort across this collaboration, we now have a reliable computational framework to simulate stellar mergers," said Patrick Motl, professor of physics at Indiana University Kokomo. "By substantially reducing the computational time to complete a simulation, we can begin to ask new questions that could not be addressed when a single-merger simulation was precious and very time consuming. We can explore more parameter space, examine a simulation at very high spatial resolution or for longer times after a merger, and we can extend the simulations to include more complete physical models by incorporating radiative transfer, for example."

Recently published in Monthly Notices of the Royal Astronomical Society, "Octo-Tiger: A New, 3D Hydrodynamic Code for Stellar Mergers That Uses HPX Parallelisation," investigates the code performance and precision through benchmark testing. The authors, Dominic C. Marcello, postdoctoral researcher; Sagiv Shiber, postdoctoral researcher; Juhan Frank, professor; Geoffrey C. Clayton, professor; Patrick Diehl, research scientist; and Hartmut Kaiser, research scientist, all at Louisiana State University--together with collaborators Orsola De Marco, professor at Macquarie University and Patrick M. Motl, professor at Indiana University Kokomo--compared their results to analytic solutions, when known and other grid-based codes, such as the popular FLASH. In addition, they computed the interaction between two white dwarfs from the early mass transfer through to the merger and compared the results with past simulations of similar systems.

"A test on Australia's fastest supercomputer, Gadi (#25 in the World's Top 500 list), showed that Octo-Tiger, running on a core count over 80,000, displays excellent performance for large models of merging stars," De Marco said. "With Octo-Tiger, we cannot only reduce the wait time dramatically, but our models can answer many more of the questions we care to ask."

Octo-Tiger is currently optimized to simulate the merger of well-resolved stars that can be approximated by barotropic structures, such as white dwarfs or main sequence stars. The gravity solver conserves angular momentum to machine precision, thanks to a correction algorithm. This code uses HPX parallelization, allowing the overlap of work and communication and leading to excellent scaling properties to solve large problems in shorter time frames.

"This paper demonstrates how an asynchronous task-based runtime system can be used as a practical alternative to Message Passing Interface to support an important astrophysical problem," Diehl said.

The research outlines the current and planned areas of development aimed at tackling a number of physical phenomena connected to observations of transients.

"While our particular research interest is in stellar mergers and their aftermath, there are a variety of problems in computational astrophysics that Octo-Tiger can address with its basic infrastructure for self-gravitating fluids," Motl said.

The animation (https://www.youtube.com/watch?v=hg9MQNLLJw4) was prepared by Shiber, who says: "Octo-Tiger shows remarkable performance both in the accuracy of the solutions and in scaling to tens of thousands of cores. These results demonstrate Octo-Tiger as an ideal code for modeling mass transfer in binary systems and in simulating stellar mergers."

Anyone with children knows that while controlling one child can be hard, controlling many at once can be nearly impossible. Getting swarms of robots to work collectively can be equally challenging, unless researchers carefully choreograph their interactions -- like planes in formation -- using increasingly sophisticated components and algorithms. But what can be reliably accomplished when the robots on hand are simple, inconsistent, and lack sophisticated programming for coordinated behavior?

A team of researchers led by Dana Randall, ADVANCE Professor of Computing and Daniel Goldman, Dunn Family Professor of Physics, both at Georgia Institute of Technology, sought to show that even the simplest of robots can still accomplish tasks well beyond the capabilities of one, or even a few, of them. The goal of accomplishing these tasks with what the team dubbed "dumb robots" (essentially mobile granular particles) exceeded their expectations, and the researchers report being able to remove all sensors, communication, memory and computation -- and instead accomplishing a set of tasks through leveraging the robots' physical characteristics, a trait that the team terms "task embodiment."

The team's BOBbots, or "behaving, organizing, buzzing bots" that were named for granular physics pioneer Bob Behringer, are "about as dumb as they get," explains Randall. "Their cylindrical chassis have vibrating brushes underneath and loose magnets on their periphery, causing them to spend more time at locations with more neighbors." The experimental platform was supplemented by precise computer simulations led by Georgia Tech physics student Shengkai Li, as a way to study aspects of the system inconvenient to study in the lab.

Despite the simplicity of the BOBbots, the researchers discovered that, as the robots move and bump into each other, "compact aggregates form that are capable of collectively clearing debris that is too heavy for one alone to move," according to Goldman. "While most people build increasingly complex and expensive robots to guarantee coordination, we wanted to see what complex tasks could be accomplished with very simple robots."

Their work, as reported April 23, 2021 in the journal Science Advances, was inspired by a theoretical model of particles moving around on a chessboard. A theoretical abstraction known as a self-organizing particle system was developed to rigorously study a mathematical model of the BOBbots. Using ideas from probability theory, statistical physics and stochastic algorithms, the researchers were able to prove that the theoretical model undergoes a phase change as the magnetic interactions increase -- abruptly changing from dispersed to aggregating in large, compact clusters, similar to phase changes we see in common everyday systems, like water and ice.

"The rigorous analysis not only showed us how to build the BOBbots, but also revealed an inherent robustness of our algorithm that allowed some of the robots to be faulty or unpredictable," notes Randall, who also serves as a professor of computer science and adjunct professor of mathematics at Georgia Tech.

Osaka, Japan - Scientists at Osaka University, in cooperation with JOANNEUM RESEARCH (Weiz, Austria), introduced wireless health monitoring patches that use embedded piezoelectric nanogenerators to power themselves with harvested biomechanical energy. This work may lead to new autonomous health sensors as well as battery-less wearable electronic devices.

As wearable technology and smart sensors become increasingly popular, the problem of providing power to all of these devices become more relevant. While the energy requirements of each component may be modest, the need for wires or even batteries become burdensome and inconvenient. That is why new energy harvesting methods are needed. Also, the ability for integrated health monitors to use ambient motion to both power and activate sensors will help accelerate their adoption in doctor's offices.

Now, an international team of researchers from Japan and Austria has invented new ultraflexible patches with a ferroelectric polymer that can not only sense a patient's pulse and blood pressure, but also power themselves from normal movements. The key was starting with a substrate just one micron thick. Using a strong electric field, ferroelectric crystalline domains in a copolymer were aligned so that the sample had a large electric dipole moment. Based on the piezoelectric effect, which is very efficient in converting natural motion into small electric voltages, the device responds rapidly to strain or pressure changes. These voltages can be transduced either into signals for the medical sensors or to directly harvest the energy. "Our e-health patches may be employed as part of screening for lifestyle-related diseases such as heart disorders, signs of stress, and sleep apnea," first-author Andreas Petritz says.

The authors estimate that multilayer patches can harvest up to 200 millijoules per day from biomechanical motions if placed on joints, like knees or elbows. This is enough to monitor cardiovascular parameters several times a day. And the patches are so thin that they are barely perceptible thus making a necessary evil for many patients—daily health monitoring—less unpleasant.

"We expect that our findings will assist in the development of other sheet-type sensor systems that can perform precise biomonitoring when affixed to the skin surface," senior author Tsuyoshi Sekitani says. Additional modules allow other features, such as wireless communication with a smartphone or computer.

Sophia Antipolis - 23 April 2021: A study of 2.4 million hospitalised cannabis users has found that those with an arrhythmia were 4.5 times more likely to die while in hospital than those without. The research is presented at EHRA 2021, an online scientific congress of the European Society of Cardiology (ESC).1

"People should be aware of this devastating outcome and be careful when using cannabis if they have a concomitant heart problem," said study author Dr. Sittinun Thangjui of Bassett Healthcare Network, Cooperstown, US.

Marijuana or cannabis is the most commonly used psychoactive substance worldwide.2 However, there is limited knowledge about safety of the drug in people with cardiac arrhythmias. This study examined the burden of arrhythmias in drug users admitted to hospital. It also compared length of hospital stay and deaths in hospital between those with and without an arrhythmia.

The study was conducted using the National Inpatient Sample database, which covers 97% of the US population. The study included 2,457,544 adult cannabis users admitted to hospital in 2016 to 2018. Of those, 187,825 (7.6%) patients had an arrhythmia. Atrial fibrillation was the most common, followed by abnormally slow heart rate and abnormally fast heart rate.

Patients in arrhythmia group were older: the average age was 50.5 years compared to 38.3 years for those without an arrhythmia. Those with arrhythmias also had more co-existing health conditions.

The researchers compared deaths between the two groups after adjusting for factors that could influence the relationship including age, sex, race, income, diabetes, heart failure, chronic kidney disease, obesity, and hospital location. Cannabis users with an arrhythmia had a 4.5 times higher odds of in-hospital mortality compared to those without an arrhythmia. Patients with an arrhythmia had a longer length of hospital stay (5.7 days) compared to those without (5.1 days).

Dr. Thangjui said: "Our study highlights that heart rhythm disorders may be a warning sign for an increased risk of death in people who use cannabis. More studies are needed to confirm our results. In the meantime, it seems sensible to screen these patients for arrhythmias if they present to hospital so that those with a heart rhythm problem can be closely monitored."

Among the first lessons any grade school science student learns is that white light is not white at all, but rather a composite of many photons, those little droplets of energy that make up light, from every color of the rainbow - red, orange, yellow, green, blue, indigo, violet.

Now, researchers at Stanford University have developed an optical device that allows engineers to change and fine-tune the frequencies of each individual photon in a stream of light to virtually any mixture of colors they want. The result, published April 23 in Nature Communication, is a new photonic architecture that could transform fields ranging from digital communications and artificial intelligence to cutting-edge quantum computing.

"This powerful new tool puts a degree of control in the engineer's hands not previously possible," said Shanhui Fan, a professor of electrical engineering at Stanford and senior author of the paper.

The clover-leaf effect

The structure consists of a low-loss wire for light carrying a stream of photons that pass by like so many cars on a busy throughway. The photons then enter a series of rings, like the off-ramps in a highway cloverleaf. Each ring has a modulator that transforms the frequency of the passing photons - frequencies which our eyes see as color. There can be as many rings as necessary, and engineers can finely control the modulators to dial in the desired frequency transformation.

Among the applications that the researchers envision include optical neural networks for artificial intelligence that perform neural computations using light instead of electrons. Existing methods that accomplish optical neural networks do not actually change the frequencies of the photons, but simply reroute photons of a single frequency. Performing such neural computations through frequency manipulation could lead to much more compact devices, say the researchers.

"Our device is a significant departure from existing methods with a small footprint and yet offering tremendous new engineering flexibility," said Avik Dutt, a post-doctoral scholar in Fan's lab and second author of the paper.

Seeing the light

The color of a photon is determined by the frequency at which the photon resonates, which, in turn, is a factor of its wavelength. A red photon has a relatively slow frequency and a wavelength of about 650 nanometers. At the other end of the spectrum, blue light has a much faster frequency with a wavelength of about 450 nanometers.

A simple transformation might involve shifting a photon from a frequency of 500 nanometers to, say, 510 nanometers - or, as the human eye would register it, a change from cyan to green. The power of the Stanford team's architecture is that it can perform these simple transformations, but also much more sophisticated ones with fine control.

To further explain, Fan offers an example of an incoming light stream comprised of 20 percent photons in the 500-nanometer range and 80 percent at 510 nanometers. Using this new device, an engineer could fine-tune that ratio to 73 percent at 500 nanometers and 27 percent at 510 nanometers, if so desired, all while preserving the total number of photons. Or the ratio could 37 and 63 percent, for that matter. This ability to set the ratio is what makes this device new and promising. Moreover, in the quantum world, a single photon can have multiple colors. In that circumstance, the new device actually allows changing of the ratio of different colors for a single photon.

"We say this device allows for 'arbitrary' transformation but that does not mean 'random,'" said Siddharth Buddhiraju, who was a graduate student in Fan's lab during the research and is first author of the paper and who now works at Facebook Reality Labs. "Instead, we mean that we can achieve any linear transformation that the engineer requires. There is a great amount of engineering control here."

"It's very versatile. The engineer can control the frequencies and proportions very accurately and a wide variety of transformations are possible," Fan added. "It puts new power in the engineer's hands. How they will use it is up to them."

Sugar is not just something we eat. On the contrary. Sugar is one of the most naturally occurring molecules, and all cells in the body are covered by a thick layer of sugar that protects the cells from bacteria and virus attacks. In fact, close to 80 per cent of all viruses and bacteria bind to the sugars on the outside of our cells.

Sugar is such an important element that scientists refer to it as the third building block of life - after DNA and protein. And last autumn, a group of researchers found that the spike protein in corona virus needs a particular sugar to bind to our cells efficiently.

Now the same group of researchers have completed a new study that further digs into the cell receptors to which sugars and thus bacteria and virus bind.

'We have established how the sugars bind to and activate the so-called Siglec receptors that regulate immunity. These receptors play a major role, as they tell the immune system to decrease or increase activities. This is an important mechanism in connection with autoimmune diseases', says the first author of the study, Postdoc Christian Büll from the Copenhagen Center for Glycomics (CCG) at the University of Copenhagen.

The unique sugar language

When the immune system receives wrong signals, it can lead to autoimmune diseases, which is when the immune system attacks itself. The Siglec receptors receive signals via the sialic acid sugar, a carbohydrate that typically closes the sugar chains on the surface of our cells. When Siglec receptors meet the right sugar chains, the immune system is told to dampen or activate.

'As part of the new study, we have created a cell library that can be used to study how various sugars bind to and interact with receptors. We have done this by creating tens of thousands of cells each containing a bit of the unique sugar language, which enables us to distinguish them from one another and to study their individual effect and process. This knowledge can help us develop better treatment options in the future', says Associate Professor Yoshiki Narimatsu from CCG, who also contributed to the study.

'The surface of the cells in the library is the same as the one found on cells in their natural environment. This means that we can study the sugars in an environment with the natural occurrence of e.g. proteins and other sugars, and we can thus study the cells in the form in which virus and bacteria find them', Yoshiki Narimatsu explains.

Important discovery for Alzheimer's

Working on the new study, the researchers identified the sugars that bind to the specific receptor that plays a main role in the development of Alzheimer's disease.

'Our main finding concerns the Siglec-3 receptor. Mutations in the Siglec-3 receptor is already known to play a role in connection with Alzheimer's, but we did not know what the receptor specifically binds to. Our method has now identified a potential natural sugar that binds specifically to the Siglec-3 receptor. This knowledge represents an important step forwards in understanding the genetic defects that cause a person to develop the disease', says Christian Büll.

It is 2,250 kilometers long, but only 355 kilometers wide at its widest point - on a world map, the Red Sea hardly resembles an ocean. But this is deceptive. A new, albeit still narrow, ocean basin is actually forming between Africa and the Arabian Peninsula. Exactly how young it is and whether it can really be compared with other young oceans in Earth's history has been a matter of dispute in the geosciences for decades. The problem is that the newly formed oceanic crust along the narrow, north-south aligned rift is widely buried under a thick blanket of salt and sediments. This complicates direct investigations.

In the international journal Nature Communications, scientists from GEOMAR Helmholtz Centre for Ocean Research Kiel, King Abdullah University for Science and Technology in Thuwal (Saudi Arabia) and the University of Iceland have now published a study that makes a good case for the Red Sea being quite mature and having an almost classical oceanic evolution. "Using a combination of different methods, we can show for the first time that the structures in the Red Sea are typical for a young but already fully developed ocean basin." says Dr. Nico Augustin from GEOMAR, lead author of the study.

In addition to information from high-resolution seafloor maps and chemical investigations of rock samples, the team primarily used gravity and earthquake data to develop a new tectonic model of the Red Sea basin. Gravity anomalies have already helped to detect hidden seafloor structures such as rift axes, transform faults and deep-sea mountains in other regions, for example in the Gulf of Mexico, the Labrador Sea or the Andaman Sea.

The authors of the current study compared gravity patterns of the Red Sea axis with comparable mid-ocean ridges and found more similarities than differences. For example, they identified positive gravity anomalies running perpendicular to the rift axis, which are caused by variations in crustal thickness running along the axis. "These so-called 'off-axis segmentation trails' are very typical features of oceanic crust originating from magmatically more active, thicker and thus, heavier areas along the axis. However, this observation is new for the Red Sea," says Dr. Nico Augustin.

Bathymetric maps as well as earthquake data also support the idea of an almost continuous rift valley throughout the Red Sea basin. This is also confirmed by geochemical analyses of rock samples from the few areas that are not overlain by salt masses. "All the samples we have from the Red Sea rift have geochemical fingerprints of normal oceanic crust," says Dr. Froukje van der Zwan, co-author of the study.

With this new analysis of gravity and earthquake data, the team constrains the onset of ocean expansion in the Red Sea to about 13 million years ago. "That's more than twice the generally accepted age," Dr. Augustin says. That means the Red Sea is no longer a baby ocean, but a young adult with a structure similar to the young southern Atlantic some 120 million years ago.

The model now presented is, of course, still being debated in the scientific community, says the lead author, "but it is the most straightforward interpretation of what we observe in the Red Sea. Many details in salt- and sediment-covered areas that were previously difficult to explain suddenly make sense with our model." While it has thus been able to answer some questions about the Red Sea, the model also raises many new ones that inspire further research in the Red Sea from a whole new scientific perspective.

Tsukuba, Japan - Blood vessels can be injured by the build-up of atherosclerosis and long-standing hypertension, among other conditions. As a consequence, blood vessels may undergo a process called remodeling, whereby their walls thicken and cause blockages (known as occlusion). In a new study, researchers from the University of Tsukuba discovered how cells marked by platelet-derived growth factor receptor alpha (PDGFRa+) residing predominantly in the most outer layer of blood vessels contribute to their remodeling.

Blood vessels comprise three layers, each of which fulfills a unique role in the function and stability of blood vessels: The innermost layer (the intima) is lined with endothelial cells that regulate the exchange between the blood and tissues; the medial layer (the media) consists of smooth muscle cells that regulate the tone of the blood vessel; and the outermost layer (the adventitia) contains various cell types and connective tissue to provide structural integrity and stability to the blood vessels. The intima is highly sensitive to pathologic conditions, such as atherosclerosis and hypertension, but also vascular occlusion due to stent implantation (also called in-stent restenosis). When the intima is damaged, the blood vessel undergoes remodeling, whereby smooth muscle cells in the media multiply and result in the blocking of the vessel wall. While adventitial cells are also known to contribute to this process, how and to what extent they do so remains unknown.

"Neointima formation is a major complication of vascular disorders and stent implantations," says lead author of the study Assistant Professor Kenichi Kimura. "Because they contribute to the overall morbidity and mortality of patients, it's important to understand the mechanism leading to neointima formation, so we can provide a therapeutic approach to patients. The role of the media in neointima formation has been heavily studied in the past. Therefore, in this study we wanted to understand how adventitial cells may contribute to it."

To achieve their goal, the researchers used lineage tracing and marked PDGFRa+ cells of mice with a fluorescent protein. By doing so, they were able to identify and track cell populations and their progeny over time. To understand how PDGFRa+ cells contribute to neointima formation, the researchers applied three different types of injury to blood vessels of mice: Carotid artery ligation (tying off the major blood vessel in the neck), denudation (using a wire to injure the blood vessel from within) and pressure overload (tying off the aorta to increase the blood pressure in the vessels arising from the aorta).

Intriguingly, the researchers found that the responses of the PDGFRa+ cells differed depending on the type of injury. While these cells populated the neointima slowly and developed into immature vessel muscle cells after carotid artery ligation, this process was accelerated in the case of denudation injury and PDGFRa+ cells developed into mature vessel smooth muscle cells. Furthermore, after pressure overload injury, PDGFRa+ cells proliferated in the adventitia and produced connective tissue there.

"These are striking results that show how PDGFRa+ cells exhibit a context-dependent response to vascular injuries. We hope that our findings may help provide a new therapeutic avenue for patients affected by neointima formation and vessel occlusion," says Professor Hiromi Yanagisawa.