Saturday, May 23, 2020

Supercomputer model simulations reveal cause of Neanderthal extinction

INSTITUTE FOR BASIC SCIENCE

IMAGE: COMPUTER SIMULATIONS OF POPULATION DENSITY OF NEANDERTHALS (LEFT) AND HOMO SAPIENS (RIGHT) 43,000 YEARS AGO (UPPER) AND 38,000 YEARS AGO (LOWER). ORANGE (GREEN) CIRCLES INDICATE ARCHEOLOGICAL SITES OF NEANDERTHALS (HOMO... view more

CREDIT: IBS

Climate scientists from the IBS Center for Climate Physics discover that, contrary to previously held beliefs, Neanderthal extinction was neither caused by abrupt glacial climate shifts, nor by interbreeding with Homo sapiens. According to new supercomputer model simulations, only competition between Neanderthals and Homo sapiens can explain the rapid demise of Neanderthals around 43 to 38 thousand years ago.

Neanderthals lived in Eurasia for at least 300,000 years. Then, around 43 to 38 thousand years ago they quickly disappeared off the face of the earth, leaving only weak genetic traces in present-day Homo sapiens populations. It is well established that their extinction coincided with a period of rapidly fluctuating climatic conditions, as well as with the arrival of Homo sapiens in Europe. However, determining which of these factors was the dominant cause, has remained one of the biggest challenges of evolutionary anthropology.

To quantify which processes played a major role in the collapse of Neanderthal populations one needs to use mathematical models that can realistically simulate the migration of Neanderthals and Homo sapiens, their interactions, competition and interbreeding in a changing climatic environment. Such models did not exist previously.

In a new paper published in the journal Quaternary Science Review, Axel Timmermann, Director of the IBS Center for Climate Physics at Pusan National University, presents the first realistic computer model simulation of the extinction of Neanderthals across Eurasia (Figure 1). The model which is comprised of several thousands of lines of computer code and is run on the IBS supercomputer Aleph, solves a series of mathematical equations that describe how Neanderthals and Homo sapiens moved in a time-varying glacial landscape and under shifting temperature, rainfall and vegetation patterns. In the model both hominin groups compete for the same food resources and a small fraction is allowed to interbreed. The key parameters of the model are obtained from realistic climate computer model simulations, genetic and demographic data.

"This is the first time we can quantify the drivers of Neanderthal extinction," said Timmermann. "In the computer model I can turn on and off different processes, such as abrupt climate change, interbreeding or competition" he said. By comparing the results with existing paleo-anthropological, genetic and archeological data (e.g. Figure 1), Timmermann demonstrated that a realistic extinction in the computer model is only possible, if Homo sapiens had significant advantages over Neanderthals in terms of exploiting existing food resources. Even though the model does not specify the details, possible reasons for the superiority of Homo sapiens could have been associated with better hunting techniques, stronger resistance to pathogens or higher level of fecundity.

What exactly caused the rapid Neanderthal demise has remained elusive for a long time. This new computer modeling approach identifies competitive exclusion as the likely reason for the disappearance of our cousins. "Neanderthals lived in Eurasia for the last 300,000 years and experienced and adapted to abrupt climate shifts, that were even more dramatic than those that occurred during the time of Neanderthal disappearance. It is not a coincidence that Neanderthals vanished just at the time, when Homo sapiens started to spread into Europe" says Timmermann. He adds "The new computer model simulations show clearly that this event was the first major extinction caused by our own species".

A research team at the IBS Center for Climate Physics is now improving the computer model to also include megafauna and implement more realistic climate forcings. "This is a new field of research in which climate scientists can interact with mathematicians, geneticists, archeologists and anthropologists", said Axel Timmermann.

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Bumblebees speed up flowering by piercing plants

by Peter Rüegg, ETH Zurich

When pollen is in short supply, bumblebees damage plant leaves in a way that accelerates flower production, as an ETH research team headed up by Consuelo De Moraes and Mark Mescher has demonstrated.

Spring has sprung earlier than ever before this year, accompanied by temperatures more typical of early summertime. Many plants were already in full bloom by mid-April, about three to four weeks earlier than normal. These types of seasonal anomalies are becoming increasingly frequent due to climate change, and the resulting uncertainty threatens to disrupt the timing of mutualistic relationships between plants and their insect pollinators.

A research team led by ETH Professors Consuelo De Moraes and Mark Mescher has now discovered that one peculiar bumblebee behavior may help to overcome such challenges by facilitating coordination between the bees and the plants they pollinate. The group has found that bumblebee workers use their mouth parts to pinch into the leaves of plants that haven't flowered yet, and that the resulting damage stimulates the production of new flowers that bloom earlier than those on plants that haven't been given this "nudge."

Credit: ETH Zurich

Their study has just been published in the journal Science. "Previous work has shown that various kinds of stress can induce plants to flower, but the role of bee-inflicted damage in accelerating flower production was unexpected," Mescher says.

Surprising behavior from bumblebees

The researchers first noticed the behavior during other experiments being undertaken by one of the authors, Foteini Pashalidou: pollinators were biting the leaves of test plants in the greenhouse. "On further investigation, we found that others had also observed such behaviors, but no one had explored what the bees were doing to the plants or reported an effect on flower production," Mescher explains.

Following up on their observations, the ETH researchers devised several new laboratory experiments, and also conducted outdoor studies using commercially available bumblebee colonies—typically sold for the pollination of agricultural crops—and a variety of plant species.

Based on their lab studies, the researchers were able to show that the bumblebees' propensity to damage leaves has a strong correlation with the amount of pollen they can obtain: Bees damage leaves much more frequently when there is little or no pollen available to them. They also found that damage inflicted on plant leaves had dramatic effects on flowering time in two different plant species. Tomato plants subjected to bumblebee biting flowered up to 30 days earlier than those that hadn't been targeted, while mustard plants flowered about 14 days earlier when damaged by the bees.

"The bee damage had a dramatic influence on the flowering of the plants—one that has never been described before," De Moraes says. She also suggests that the developmental stage of the plant when it is bitten by bumblebees may influence the degree to which flowering is accelerated, a factor the investigators plan to explore in future work.

The researchers tried to manually replicate the damage patterns caused by bees to see if they could reproduce the effect on flowering time. But, while this manipulation did lead to somewhat earlier flowering in both plant species, the effect was not nearly as strong as that caused by the bees themselves. This leads De Moraes to suggest that some chemical or other cue may also be involved. "Either that or our manual imitation of the damage wasn't accurate enough," she says. Her team is currently trying to identify the precise cues responsible for inducing flowering and characterizing the molecular mechanisms involved in the plant response to bee damage.

Phenomenon also observed in the field

The ETH research team was also able to observe the bees' damaging behavior under more natural conditions, with doctoral student Harriet Lambert leading follow-up studies on the rooftops of two ETH buildings in central Zurich. In these experiments, the researchers again observed that hungry bumblebees with insufficient pollen supplies frequently damaged the leaves of non-blooming plants. But the damaging behavior was consistently reduced when the researchers made more flowers available to the bees.

Furthermore, it was not only captive-bred bumblebees from the researchers' experimental colonies that damaged plant leaves. The investigators also observed wild bees from at least two additional bumblebee species biting the leaves of plants in their experimental plots. Other pollinating insects, such as honeybees, did not exhibit such behavior, however: they seemed to ignore the non-flowering plants entirely, despite being frequent visitors to nearby patches of flowering plants.

Delicate balance starting to tip

"Bumblebees may have found an effective method of mitigating local shortages of pollen," De Moraes says. "Our open fields are abuzz with other pollinators, too, which may also benefit from the bumblebees' efforts." But it remains to be seen whether this mechanism is sufficient to overcome the challenges of changing climate. Insects and flowering plants have evolved together, sharing a long history that strikes a delicate balance between efflorescence and pollinator development. However, global warming and other anthropogenic environmental changes have the potential to disrupt the timing of these and other ecologically important interactions among species. Such rapid environmental change could result in insects and plants becoming increasingly out of sync in their development, for example. "And that's something from which both sides stand to lose," Mescher says.'Bee' thankful for the evolution of pollen

More information: Foteini G. Pashalidou et al. Bumble bees damage plant leaves and accelerate flower production when pollen is scarce, Science (2020). DOI: 10.1126/science.aay0496

Journal information: Science

Provided by ETH Zurich

When do plants help or hinder each other?

by Universitaet Tübingen

When plants grow close together, each individual plant has less chance of doing well—at least, that was the accepted wisdom in environmental research. Now Dr. Ruichang Zhang and Professor Katja Tielbörger from the Institute of Evolution and Ecology at the University of Tübingen are challenging that principle. Their investigation of the combined effects of environmental stress and competition on plants has led them to develop a new theoretical model suggesting that plants can 'help' each other out. The researchers were able to confirm their model predictions in detail in an experiment with real plants. Their study has been published in the latest Nature Communications.

Competition leads to fewer resources being available for each individual organism. "If the crowding becomes too much, this can even lead to the death of individual plants," says Katja Tielbörger. Yet there are many empirical studies that show that plants can also facilitate each other. Tielbörger says this is often the case when plants grow under stressful conditions—for instance, when the soil is saline or the temperatures are high. "When it's very hot, for example, large plants can provide shade, which in turn can create better conditions for smaller plants that grow under the canopy of the larger ones," she adds. It seems logical that such positive interactions are most important when environmental stress is high. It has therefore long been postulated that facilitation in bad times may turn into competition when conditions are good.

Experiments with Arabidopsis

The two Tübingen researchers have now combined the density and stress factors in a novel mathematical model. "This showed that under intense stress, it can be advantageous to have many neighbors and that competition only occurs at very high densities," Tielbörger sums up. From the point of view of the individual plant, the relationship between density and thriving is like a hump-shaped curve. The Tübingen researchers simulated the model conditions in an experiment using Arabidopsis thaliana or thale cress—the plant commonly used as a model in molecular biology. "The experiment confirmed all the predictions arising from our model," says Tielbörger. For example, the plants suffered considerably less from salt stress when they had many neighbors. And they suffered from competition by neighbors only when they were not under stress.

Because of the complexity of ecological systems, models are a popular method for better understanding nature. Tielbörger says it is remarkable to find such a close match between theory and reality in ecological research: "This shows how robust and universally valid our actually quite simple model is." The model may help to better predict the response of plants to stress—such as increased heat and drought—which are to be expected as the climate changes.Hormone keys plant growth or stress tolerance, but not both

More information: Ruichang Zhang et al. Density-dependence tips the change of plant–plant interactions under environmental stress, Nature Communications (2020). DOI: 10.1038/s41467-020-16286-6

Journal information: Nature Communications

Provided by Universitaet Tübingen

Researchers create global arsenic-in-groundwater maps to highlight threats

by Bob Yirka , Phys.org

Modeled probability of arsenic concentration in groundwater exceeding 10 µg per liter (red: high probability, blue: low probability). Credit: Joel Podgorski, Michael Berg, Eawag

A pair of researchers at the Swiss Federal Institute of Aquatic Science and Technology has created a global map that highlights areas where there are likely dangerous levels of arsenic in groundwater. In their paper published in the journal Science, Joel Podgorski and Michael Berg describe combining data from a variety of sources to train a machine learning algorithm to highlight possible hot spots on a global map. Yan Zheng, with Southern University of Science and Technology has published a Perspective piece outlining the work by the research pair in the same journal issue.

The current pandemic has captured the attention of the world, and for good reason. But other threats continue to put millions of people at risk. One of these, as Zheng notes, is arsenic consumption. Commonly known as a type of poison used to kill rivals, arsenic is a metalloid that, when consumed, can cause serious medical problems and, of course, death. It is also a chemical element that is commonly found in soil and rocks. In some cases, conditions exist that allow arsenic to make its way into groundwater, where it can be pulled up and consumed, putting people at risk.

Scientists have been aware of the problem of arsenic poisoning groundwater in such places as Argentina, Bangladesh and Vietnam. The WHO is also aware of the problem—they have set a concentration of 10 micrograms per liter as a safety limit in consumable water. In this new effort, Podgorski and Berg, an environmental scientist and hydrologist respectively, suspected that there are likely more hotspots than are currently known, so they set themselves the task of revealing likely hotspots around the world by analyzing vast amounts of data.

Play

https://phys.org/news/2020-05-global-arsenic-in-groundwater-highlight-threats.html

Modeled probability of arsenic concentration in groundwater exceeding 10 µg per liter (red: high probability, blue: low probability). Credit: Joel Podgorski, Michael Berg, Eawag

The work involved assembling data from over 80 studies and then using a machine learning algorithm that processed the data and made estimates on the likelihood of arsenic levels in groundwater for 1-km2-patches covering the entire globe. They then used the predictions to create a map showing arsenic threat levels. The map showed that up to 220 million people around the globe may be at risk of drinking water contaminated with dangerous levels of arsenic.

Play

https://phys.org/news/2020-05-global-arsenic-in-groundwater-highlight-threats.html

Modeled probability of arsenic concentration in groundwater exceeding 10 µg per liter (red: high probability, blue: low probability). Credit: Joel Podgorski, Michael Berg, Eawag

River-groundwater hot spot for arsenic

More information: Joel Podgorski et al. Global threat of arsenic in groundwater, Science (2020). DOI: 10.1126/science.aba1510

Environmentalists suggest COVID-19 could represent a new opportunity for a more diverse future

by Bob Yirka , Phys.org

tropical plants — Credit: CC0 Public Domain

A team of environmental researchers at the Australian Rivers Institute–Coast & Estuaries, School of Environment and Science, Griffith University, is suggesting in a Letters piece in the journal Science that the COVID-19 pandemic could represent a new opportunity for a more diverse future—they suggest that with proper planning, we could use what has been learned from the global lockdown to improve global biodiversity.

As the global pandemic has kept millions of people the world over isolating in their homes, nature has reacted. Reports of wild animals roaming city streets and small towns alike have made headlines. Also, the air has become cleaner, and many cities have become quiet. Such changes have served as a reminder that humans are not the sole residents of planet Earth.

In their paper, the team in Australia suggests that the changes we have observed might be presenting the world with a new opportunity to alter the ways that governments and environmentalists approach the issue of diversification as we move into a post-pandemic world. They note that history has shown that dramatic world events can lead to change—the Chernobyl meltdown in Ukraine, for example, led to humans abandoning huge swaths of land, allowing nature to take its course. The result has been the creation of a very large wilderness area now designated as an ecological reserve.

Another example was the Columbian conflict, which, for years, served as a protection zone for plants and animals because humans were afraid to venture into areas occupied by armed rebels. They suggest the lockdown effect could have a similar impact if long-term strategies are put in place to preserve the positive changes that nature has made, and to expand on them to increase biodiversity in other places.

The key, they claim, is for legislation protecting areas where biodiversity is present and to push for more areas to join them. They also note that the lockdown has coaxed people into rethinking some of their consumer habits—and maybe to changing some as the pandemic ends. They argue that the pandemic could represent a tipping-point in how the human race views the planet. This could be a time for development of new strategies, they suggest, and to implement them—to tip the balance in favor of a more diverse, environmentally friendly planet.Review study shows social interaction a major factor in both morbidity and mortality

More information: Jennifer Sills et al. COVID-19 recovery can benefit biodiversity, Science (2020). DOI: 10.1126/science.abc1430

Journal information: Science

Discovery about the edge of fusion plasma could help realize fusion power

by John Greenwald, Princeton Plasma Physics Laboratory

MAY 22, 2020

PPPL physicist Ammar Hakim, left, and graduate student Noah Mandell with figures from Mandell's paper showing the first computer simulations of kinetic plasma turbulence near the edge of fusion devices that can account for fluctuations of magnetic field lines. Credit: Elle Starkman/PPPL Office of Communications and Krell Institute; composite by Elle Starkman.

A major roadblock to producing safe, clean and abundant fusion energy on Earth is the lack of detailed understanding of how the hot, charged plasma gas that fuels fusion reactions behaves at the edge of fusion facilities called "tokamaks." Recent breakthroughs by researchers at the U.S. Department of Energy's (DOE) Princeton Plasma Physics Laboratory (PPPL) have advanced understanding of the behavior of the highly complex plasma edge in doughnut-shaped tokamaks on the road to capturing the fusion energy that powers the sun and stars. Understanding this edge region will be particularly important for operating ITER, the international fusion experiment under construction in France to demonstrate the practicality of fusion energy.

First-of-a-kind finding

Among the first-of-a-kind findings has been the discovery that accounting for the turbulent fluctuations in the magnetic fields that confine the plasma that fuels fusion reactions can significantly reduce the turbulent particle flux near the plasma edge. Computer simulations show that the net particle flux can go down by as much as 30 percent, despite the fact that the average magnitude of turbulent particle density fluctuation goes up by 60 percent—indicating that even though the turbulent density fluctuations are more virulent, they are moving particles out of the device less effectively.

Researchers have developed a specialized code called "Gkeyll"—pronounced just like "Jekyll" in Robert Louis Stevenson's "The Strange Case of Dr. Jekyll and Mr. Hyde"—that makes these simulations feasible. The mathematical code, a form of modeling called "gyrokinetics," simulates the orbiting of plasma particles around the magnetic field lines at the edge of a fusion plasma.

"Our recent paper summarizes the Gkeyll group's efforts in the area of gyrokinetic simulation," said PPPL physicist Ammar Hakim, lead author of a Physics of Plasmas paper that provides an overview of the group's achievements, based on an invited talk he gave at the American Physical Society's Division of Plasma Physics (APS-DPP) conference last Fall. The research, coauthored by scientists from six institutions, adapts a state-of-the-art algorithm to the gyrokinetic system to develop the "key numerical breakthroughs needed to provide accurate simulations," Hakim said.

Worldwide effort

Such breakthroughs are part of the worldwide effort to grasp the science behind the production of fusion reactions on Earth. Fusion reactions combine light elements in the form of plasma—the hot, charged state of matter composed of free electrons and atomic nuclei that makes up 99 percent of the visible universe—to generate massive amounts of energy that could provide a virtually inexhaustible supply of power to generate electricity for humanity.

Noah Mandell, a graduate student in the Princeton University Program in Plasma Physics, built on the team's work to develop the first gyrokinetic code able to handle magnetic fluctuations in what is called the plasma scrape-off layer (SOL) at the edge of tokamak plasmas. The British Journal of Plasma Physics has published andhighlighted his report as a featured article .

Mandell explores how blob-like plasma turbulence bends magnetic field lines, leading to the dynamics of "dancing field lines." He finds that field lines usually move smoothly but when dancing can abruptly reconfigure into reconnection events that cause them to converge and violently snap apart.

Mandell's findings are best described as "proof-of-concept" with regard to the magnetic fluctuations, he said. "We know there are more physical effects that need to be added to the code for detailed comparisons with experiments, but already the simulations are showing interesting properties near the plasma edge," he said. "The ability to handle bending of the magnetic field lines will also be essential for future simulations of edge localized modes (ELMs), which we would like to do better to understand the bursts of heat they cause that must be controlled to prevent tokamak damage."

Very challenging

What makes this finding unique is that previous gyrokinetic codes have simulated SOL blobs but assumed that the field lines were rigid, Mandell noted. Extending a gyrokinetic code to calculate the movement of magnetic fields lines is computationally very challenging, requiring special algorithms to ensure that two large terms balance each other to an accuracy of better than 1 part in a million.

Moreover, while codes that model turbulence in the core of the tokamak can include magnetic fluctuations, such codes cannot simulate the SOL region. "The SOL requires specialized codes like Gkeyll that can handle much larger plasma fluctuations and interactions with the walls of the reactor," Mandell said.

Future steps for the Gkeyll group will include investigating the precise physical mechanism that affects the dynamics of the plasma edge, an effect likely connected to the bending field lines. "This work provides stepping stones that I think are very important," Hakim said. "Without the algorithms that we made, these findings would be very difficult to apply to ITER and other machines."

New explanation for sudden collapses of heat in plasmas can help create fusion energy on Earth

More information: N. R. Mandell et al, Electromagnetic full- gyrokinetics in the tokamak edge with discontinuous Galerkin methods, Journal of Plasma Physics (2020).

DOI: 10.1017/S0022377820000070

Does MRI have an environmental impact?

Gadolinium found in elevated amounts near water treatment plants in Tokyo rivers

TOKYO METROPOLITAN UNIVERSITY

NEWS RELEASE 23-MAY-2020

IMAGE: SAMPLES WERE TAKEN ALONG RIVERS AROUND TOKYO. MEASUREMENTS OF RARE EARTH ELEMENT QUANTITIES INDICATE A CLEARLY ELEVATED AMOUNT OF GADOLINIUM COMPARED TO THAT IN NATURAL SHALE. view more

CREDIT: TOKYO METROPOLITAN UNIVERSITY

Tokyo, Japan - Researchers from Tokyo Metropolitan University have surveyed the amount of gadolinium found in river water in Tokyo. Gadolinium is contained in contrast agents given to patients undergoing medical magnetic resonance imaging (MRI) scans, and it has been shown in labs to become toxic when exposed to ultraviolet rays. The researchers found significantly elevated levels, particularly near water treatment plants, highlighting the need for new public policy and removal technologies as MRI become even more commonplace.

Modern medicine owes a lot to magnetic resonance imaging (MRI). Doctors can see tumors, inflammation and hemorrhaging deep inside the human body without the need for invasive surgery; unlike CT scans, patients are also not exposed to any ionizing radiation. Its many benefits have meant that MRI machines are now more wide-spread than ever. For example, in 1995, Japan had 6.12 machines per million residents; in 2017, it had 55.21, the highest number per million in the world.

But it might not be all good news. MRI imaging is often carried out after patients are injected with a contrast agent which makes features inside the body clearer in scans. It contains gadolinium, an originally toxic rare earth element that is rendered safe for medical use by binding it to a chelation agent, making it unreactive. After completing its task, 98% of the compound is expelled from a patient's body within 24 hours in the urine and makes its way through the wastewater system. Common wastewater treatment plants cannot remove it, so it passes directly into the environment, albeit in small quantities. On exposure to UV light, lab experiments have shown that it may transform back into a toxic state. This makes it vital to track how much gadolinium finds its way into the environment.

Thus, a team led by Professor Kazumasa Inoue of Tokyo Metropolitan University set out to measure how much gadolinium was being released into rivers in Tokyo. They took samples from a number of locations along the many major rivers of the city. Correcting for the amounts expected in natural shale, they carried out a broad survey of rare earths using mass spectrometry and found a significant elevation in the amount of gadolinium in the water. Importantly, they noticed large spikes in the amounts depending on proximity to water treatment plants. These findings are in agreement with previous work for samples taken inside a treatment plant on the River Weser, Germany.

It should be remembered that the reason why gadolinium is released in the first place is that a patient's kidneys safely pass it from the body. This means that, for the most part, it is also non-reactive in the environment. But as more MRI machines are installed to cater to an ageing population with more healthcare needs, the research team noted that new public policy and the development of new treatment techniques are vital to mitigating the environmental impact of this well-established, lifesaving medical technology.

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Now closer to reality: Prosthetics that can feel

by Daniel Strain, University of Colorado at Boulder

Humans do a lot of things with their hands: We squeeze avocados at the grocery story, scratch our dogs behind the ears and hold our significant others' hands. They are things that many people who have lost limbs can't do.

CU Boulder biomedical engineer Jacob Segil is working to bring back that sense of touch for amputees, including veterans of the wars in Iraq and Afghanistan.

Segil, an instructor in the Engineering Plus Program and program director for the Center for Translational Research at CU Boulder, is part of a long-running effort to achieve the stuff of science fiction: designing artificial limbs that may one day allow amputees to feel the world around them through electronic sensors. Picture Luke Skywalker twitching after he gets poked in his robotic hand.

"In my field, we have a gold standard, which is the physiological hand," said Segil, also a research healthcare scientist at the U.S. Department of Veterans Affairs. "We're trying to recreate it, and we're still so far off."

Far off, but closer than you might think. Through an effort led by Case Western Reserve University and the VA, Segil and his colleagues have used a unique "neural interface" to give a small number of amputees back the sense of touch in their missing fingers. In a new study, published this month in the journal Scientific Reports, the team demonstrated just how effective this sensory restoration technology can be—helping one amputee to feel his hand adopt a series of postures, such as a gesture resembling the thumbs-up sign.

For Segil, who recently received a $1 million Career Development Award from the VA to continue his work, the project is a chance to use his engineering skills to help real people.

"A lot of us engineers would just be happy building stuff," Segil said. "But as a VA researcher, your work can help the people who served our country. It's a powerful motivator."

Body sense

Segil grew up in a family of physicians and had long been fascinated by the idea of studying the human body as a machine—albeit a pretty complicated one.

"It's really just a bunch of wires and actuators, with a huge microprocessor in your head," Segil said.

That interest led him to earn his Ph.D. in mechanical engineering from CU Boulder and to take on a postdoctoral research position split between two VA centers: the Louis Stokes Cleveland VA Medical Center in Ohio and the Rocky Mountain Regional VA Medical Center in Aurora, Colorado. In Cleveland, Segil worked with biomedical engineer Dustin Tyler and explored the benefit of prosthetic limbs that can feel.

In the 2000s, Tyler invented a way to, essentially, hotwire the human nervous system.

His interface, called a nerve cuff electrode, surrounds the nerves and zaps them with electronic pulses. Adjust those signals just right, and they will travel to the brain, tricking it into thinking that it can feel fingers, even if there are no fingers to feel.

"We're tapping into that wire before it gets to the brain, and then the brain can't tell whether it's coming from the finger or from our artificial system," said Tyler, a professor at Case Western and a VA researcher.

To date, only four patients have undergone the surgery needed to receive that sensory feedback. But the project is a huge breakthrough in prosthetics, Segil said. He explained that while artificial hands have grown more high-tech in recent years, many amputees still choose not to use them—in large part, because these devices are numb.

"All prosthetic devices that have ever been used are 'disembodied,'" he said. "They are a tools, external to the body. They're the equivalent of a tennis player and their racket."

In the recently published case study, Segil and his colleagues began to probe whether sensing prosthetics could do more—becoming a meaningful part of a person's body.

The researchers worked with one volunteer, a man in his 40s who had lost his arm below his elbow six years before. They fed his neural interface varying patterns of sensory information—say, cues that he was picking up a penny. The group then asked the man to, while his prosthetic was hidden from view, decide what position his hand was in from a menu of seven postures.

The interface did the trick. With enough practice, the man was able to identify the seven postures with up to 95% accuracy.

"When you have five points of information, the user is able to synthesize those to get a broader view of what the state of the hand is," Tyler said.

The team is still a long way from their Star Wars moment. But it's a good start.

"I think we need to go further into this embodiment space where the artificial and the physical are blurred," Segil said. "That's the stuff the goes beyond prosthetic limbs and redefines the interface between man and machine."

Stories to tell

Segil is planning to push his mind-bending research further with his new funding, which will be split between the VA centers in Ohio and Colorado. His current work will focus on the psychology of prosthetics as much as the engineering—what will it take for amputees to think of their artificial limbs as real body parts? He also hopes that patients in Colorado will soon be able to receive their own neural interfaces.

For now, the engineer takes his inspiration from people like the (anonymous) human subject who volunteered to participate in his recent study.

"Every amputee has a story," he said. "Everyone has their physical scars, but also emotional triumphs, how they get through their day-to-day. It's a wonderful environment to work in."

New fingertip sensors to help veterans feel through their prosthetics

More information: Jacob L. Segil et al. Combination of Simultaneous Artificial Sensory Percepts to Identify Prosthetic Hand Postures: A Case Study, Scientific Reports (2020). DOI: 10.1038/s41598-020-62970-4

Journal information: Scientific Reports

Provided by University of Colorado at Boulder

A 'sole' mate to prevent diabetic foot ulcers

by UT Southwestern Medical Center

THIS IS HOW I LOST MY FOOT

A new cooling insole developed by UT Southwestern scientists reduced the foot temperature of patients with diabetic neuropathy by several degrees, diminishing a significant risk factor for diabetic foot ulcers. This new device, detailed in an article published online ahead of print May 6 in The Journal of Foot & Ankle Surgery, could eventually prevent thousands of amputations that take place worldwide each year because of this condition.

Just in the U.S., more than 100,000 lower extremity amputations take place every year, many of them prompted by diabetic foot ulcers. These ulcers are associated with numerous quality-of-life and health consequences, including a mortality rate of 50 percent within five years for patients who develop them. Although the exact cause of this common diabetes complication is unclear, high foot pressure has long been considered a prevailing cause. Consequently, the most prescribed preventive treatment for diabetic foot ulcers is pressure-relieving insoles.

However, says Metin Yavuz, D.Eng., an associate professor in the School of Health Professions' Division of Prosthetics and Orthotics at UT Southwestern Medical Center, this prophylactic intervention isn't accomplishing its goal, since diabetic amputation rates have been on the rise despite widely available pressure-reliving insoles. "Even when patients receive therapeutic shoes and insoles, education, and close monitoring," he says, "30 to 40 percent of patients who have had one diabetic foot ulcer will still develop another within a year."

Hoping to decrease these numbers, Yavuz and his colleagues focused on another risk factor for these ulcers: foot temperature. Animal studies have shown that skin maintained between 25 and 30 degrees C is less likely to break down under pressure than skin at higher temperatures. The feet of diabetic patients already tend to be warmer due to inflammation associated with the disease, Yavuz explains, compounded by friction from walking and the stiff therapeutic shoes that patients wear, which are usually made of synthetic materials that act as heat insulators.

"We thought, why don't we break that vicious cycle by cooling the foot?" he says.

To do that, Yavuz and his lab, aided by a pilot grant from UTSW's Center for Translational Medicine, developed a system that circulates cool water into pressure-relieving insoles. The device, which the researchers named Temperature and Pressure Monitoring and Regulating Insoles (TAPMARI), consists of a small box strapped to the wearer's calf that houses a cooling unit, a small water pump, a battery pack, and a thermostat. The cooling unit harnesses a type of thermoelectric cooling called the Peltier effect to chill water to a desired temperature that's then pumped into insoles placed in the wearer's shoes. Yavuz later teamed up with the engineering company Vivonics Inc. and obtained funding from the National Institutes of Health to improve the design.

The researchers tested the improved device in eight volunteers: one man and seven women of a median age of 45 years. Five of these volunteers were healthy and three had diabetic neuropathy.

Using an infrared thermal camera, the researchers took photos of the subjects' feet at baseline before wearing the insoles, then placed a cooling insole in only their right shoes. They took more thermal photos after the subjects walked five minutes on a treadmill and again after they wore the insoles an additional two hours and walked five minutes on the treadmill again.

Results showed that the mean baseline foot temperature in the group was 28.1 degrees C. Mean foot temperatures at the end of the study were 31.7 degrees C for the left foot and 25.9 degrees C for the right, which was cooled by TAPMARI. Although the diabetics' feet got warmer than those of the healthy volunteers during walking, they still maintained a mean temperature of 27.5 degrees C in the right foot, suggesting that the insoles could maintain temperature in a range that protects against skin breakdown.

Cool temperatures from the insoles didn't cause vasoconstriction (narrowing of blood vessels) in the foot, which could have damaged tissue, Yavuz says. However, sole temperatures reached as high as 30.8 degrees C in some regions of the cooled feet, particularly in the midfoot, suggesting that the design of the insole needs to be improved. Other design elements could also be tweaked, he says, such as reducing the size of the unit worn on the calf.

Eventually, Yavuz says, these devices could change the course for patients with diabetes, preventing this common and often serious complication.

"Diabetic foot ulcers can be a major burden on patients, their families, caregivers, and the health system," he says. "What we're doing now to prevent these ulcers or simply maintain the status quo isn't working. TAPMARI could be the start of a whole new approach."

Other researchers who contributed to this study include Ali Ersen and Lawrence A. Lavery of UTSW; Aakshita Monga and Yasser Salem of the University of North Texas Health Science Center; Alan Garrett of the John Peter Smith Hospital; and Gordon B. Hirschman and Ryan Myers of Vivonics Inc.

How to avoid foot amputation in diabetic patients

More information: Metin Yavuz et al, Temperature- and Pressure-Regulating Insoles for Prevention of Diabetic Foot Ulcers, The Journal of Foot and Ankle Surgery (2020). DOI: 10.1053/j.jfas.2019.05.009

Provided by UT Southwestern Medical Center

Disinfecting effect of copper on SARS-CoV-2 and other viruses
https://www.physicsforums.com/threads/disinfecting-effect-of-copper-on-sars-cov-2-and-other-viruses.989075/

May 14, 2020

When researchers reported last month that the novel coronavirus causing the COVID-19 pandemic survives for days on glass and stainless steel but dies within hours after landing on copper, the only thing that surprised Bill Keevil was that the pathogen lasted so long on copper

https://www.smithsonianmag.com/science-nature/copper-virus-kill-180974655/

Keevil, a microbiology researcher at the University of Southampton (U.K.), has studied the antimicrobial effects of copper for more than two decades. He has watched in his laboratory as the simple metal slew one bad bug after another. He began with the bacteria that causes Legionnaire's Disease and then turned to drug-resistant killer infections like Methicillin-resistant Staphylococcus aureus (MRSA). He tested viruses that caused worldwide health scares such as Middle East Respiratory Syndrome (MERS) and the Swine Flu (H1N1) pandemic of 2009. In each case, copper contact killed the pathogen within minutes. "It just blew it apart," he says.

https://www.nih.gov/news-events/news-releases/new-coronavirus-stable-hours-surfaces

The virus that causes coronavirus disease 2019 (COVID-19) is stable for several hours to days in aerosols and on surfaces, according to a new study from National Institutes of Health, CDC, UCLA and Princeton University scientists in The New England Journal of Medicine. The scientists found that severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) was detectable in aerosols for up to three hours, up to four hours on copper, up to 24 hours on cardboard and up to two to three days on plastic and stainless steel. The effect of copper seems to be independently verified. One should continue to use hand sanitizer and wear a protective face cover/mask.

https://www.physicsforums.com/threads/disinfecting-effect-of-copper-on-sars-cov-2-and-other-viruses.989075/

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