Tech

In the high plains of the central Chilean Andes, an ecosystem consisting of only a few animal species is providing researchers with new insights into how predators coexist in the wild.

"The puma and the culpeo fox are the only top predators on the landscape in the Chilean Andes," said Professor Marcella Kelly, of the College of Natural Resources and Environment. "And there isn't a wide range of prey species, in part because the guanacos [closely related to llamas] aren't typically found in these areas anymore due to over-hunting. With such a simplified ecosystem, we thought we could really nail down how two rival predators interact."

Kelly worked with Christian Osorio, a doctoral student in the Department of Fish and Wildlife Conservation, and researchers from the Pontifical Catholic University of Chile to chart the locations of and potential interactions between pumas and foxes in central Chile. They focused on three axes of interaction: spatial (where the animals are on the landscape), temporal (the timing of specific activities on a given landscape), and dietary (what each species is eating).

To understand the interplay between pumas and foxes, researchers deployed 50 camera stations across two sites in central Chile, one in the Rio Los Cipreses National Reserve and another on private land where cattle and horses are raised. They also collected scat samples at both locations to analyze the diets of pumas and foxes.

The team's findings, published in the journal Diversity, showed that while pumas and foxes overlapped significantly where they lived and what time they were active, there was little overlap in what they were eating, with the puma diet consisting primarily of a large hare species introduced from Europe, while the culpeo foxes favored smaller rabbits, rodents, and seeds. The two predator species can successfully share a landscape and hunt for food over the same nighttime hours because they are, in essence, ordering from different menus.

"It is likely that foxes have realized that when they try to hunt hares, they might run into trouble with pumas," Osorio explained. "If they are hunting smaller mammals, the pumas don't care, but if the foxes start targeting larger prey, the pumas will react."

How predator species interact is a crucial question for ecologists trying to understand the dynamics that inform ecosystem balances. And while the puma has been designated a species of least concern, the animal's populations are declining and continue to be monitored by conservationists.

"Least concern does not mean no concern," Osorio noted. "We have laws in Chile that protect the species, but the data we have to make a conservation designation are very scattered. As we accumulate more consistent and reliable data, the puma may be reclassified as vulnerable or even endangered."

The hares that comprise approximately 70 percent of the biomass in the puma's diet are a nonnative species, introduced to the area by European settlers. With guanacos absent from the landscape, the puma has had to adapt its diet to survive.

With some land managers and conservationists campaigning for the removal of the introduced hare species as a way to restore the area's native ecosystem, Kelly and Osorio note that it is important to understand that pumas would be significantly impacted by a reduction in their primary food source.

A further concern, which the two are currently researching, is the interplay between wildlife and humans. The national reserve increasingly sees visitors eager to witness big cats and foxes in their natural environment, while the sheep and cattle industries are increasingly using remote terrain for livestock cultivation.

"Pumas do occasionally kill livestock, which is a challenge we're looking into right now," said Kelly, an affiliate of Virginia Tech's Fralin Life Sciences Institute. "The government would like to preserve the puma, but there are competing challenges of what kind of threat they pose to livestock and what kind of threat cattle or sheep farming poses to them."

Understanding how two predatory species can come to coexist has the potential to provide conservationists and ecologists with better ideas for how humans and wild animals can share a landscape.

A computer vision technology developed by University of Cambridge engineers has now been developed into a free mobile phone app for regular monitoring of glucose levels in people with diabetes.

The app uses computer vision techniques to read and record the glucose levels, time and date displayed on a typical glucose test via the camera on a mobile phone. The technology, which doesn't require an internet or Bluetooth connection, works for any type of glucose meter, in any orientation and in a variety of light levels. It also reduces waste by eliminating the need to replace high-quality non-Bluetooth meters, making it a cost-effective solution to the NHS.

Working with UK glucose testing company GlucoRx, the Cambridge researchers have developed the technology into a free mobile phone app, called GlucoRx Vision, which is now available on the Apple App Store and Google Play Store.

To use the app, users simply take a picture of their glucose meter and the results are automatically read and recorded, allowing much easier monitoring of blood glucose levels.

In addition to the glucose meters which people with diabetes use on a daily basis, many other types of digital meters are used in the medical and industrial sectors. However, many of these meters still do not have wireless connectivity, so connecting them to phone tracking apps often requires manual input.

"These meters work perfectly well, so we don't want them sent to landfill just because they don't have wireless connectivity," said Dr James Charles from Cambridge's Department of Engineering. "We wanted to find a way to retrofit them in an inexpensive and environmentally-friendly way using a mobile phone app."

In addition to his interest in solving the challenge from an engineering point of view, Charles also had a personal interest in the problem. He has type 1 diabetes and needs to take as many as ten glucose readings per day. Each reading is then manually entered into a tracking app to help determine how much insulin he needs to regulate his blood glucose levels.

"From a purely selfish point of view, this was something I really wanted to develop," he said.

"We wanted something that was efficient, quick and easy to use," said Professor Roberto Cipolla, also from the Department of Engineering. "Diabetes can affect eyesight or even lead to blindness, so we needed the app to be easy to use for those with reduced vision."

The computer vision technology behind the GlucoRx app is made up of two steps. First, the screen of the glucose meter is detected. The researchers used a single training image and augmented it with random backgrounds, particularly backgrounds with people. This helps ensure the system is robust when the user's face is reflected in the phone's screen.

Second, a neural network called LeDigit detects each digit on the screen and reads it. The network is trained with computer-generated synthetic data, avoiding the need for labour-intensive labelling of data which is commonly needed to train a neural network.

"Since the font on these meters is digital, it's easy to train the neural network to recognise lots of different inputs and synthesise the data," said Charles. "This makes it highly efficient to run on a mobile phone."

"It doesn't matter which orientation the meter is in - we tested it in all types of orientations, viewpoints and light levels," said Cipolla, who is also a Fellow of Jesus College. "The app will vibrate when it's read the information, so you get a clear signal when you've done it correctly. The system is accurate across a range of different types of meters, with read accuracies close to 100%"

In addition to blood glucose monitor, the researchers also tested their system on different types of digital meters, such as blood pressure monitors, kitchen and bathroom scales. The researchers also recently presented their results at the 31st British Machine Vision Conference.

Gluco-Rx initially approached Cipolla's team in 2018 to develop a cost-effective and environmentally-friendly solution to the problem of non-connected glucose meters, and once the technology had been shown to be sufficiently robust, the company worked with the Cambridge researchers to develop the app.

"We have been working in partnership with Cambridge University on this unique solution, which will help change the management of diabetes for years to come," said Chris Chapman, Chief Operating Officer of GlucoRx. "We will soon make this solution available to all of our more than 250,000 patients."

As for Charles, who has been using the app to track his glucose levels, he said it "makes the whole process easier. I've now forgotten what it was like to enter the values in manually, but I do know I wouldn't want to go back to it. There are a few areas in the system which could still be made even better, but all in all I'm very happy with the outcome."

We are increasingly using more smart devices like smartphones, smart speakers, and wearable health and wellness sensors in our homes, offices, and public buildings. However, the batteries they use can deplete quickly and contain toxic and rare environmentally damaging chemicals, so researchers are looking for better ways to power the devices.

One way to power them is by converting indoor light from ordinary bulbs into energy, in a similar way to how solar panels harvest energy from sunlight, known as solar photovoltaics. However, due to the different properties of the light sources, the materials used for solar panels are not suitable for harvesting indoor light.

Now, researchers from Imperial College London, Soochow University in China, and the University of Cambridge have discovered that new green materials currently being developed for next-generation solar panels could be useful for indoor light harvesting. They report their findings today in Advanced Energy Materials.

Co-author Dr Robert Hoye, from the Department of Materials at Imperial, said: "By efficiently absorbing the light coming from lamps commonly found in homes and buildings, the materials we investigated can turn light into electricity with an efficiency already in the range of commercial technologies. We have also already identified several possible improvements, which would allow these materials to surpass the performance of current indoor photovoltaic technologies in the near future."

The team investigated 'perovskite-inspired materials', which were created to circumvent problems with materials called perovskites, which were developed for next-generation solar cells. Although perovskites are cheaper to make than traditional silicon-based solar panels and deliver similar efficiency, perovskites contain toxic lead substances. This drove the development of perovskite-inspired materials, which are instead based on safer elements like bismuth and antimony.

Despite being more environmentally friendly, these perovskite-inspired materials are not as efficient at absorbing sunlight. However, the team found that the materials are much more effective at absorbing indoor light, with efficiencies that are promising for commercial applications. Crucially, the researchers demonstrated that the power provided by these materials under indoor illumination is already sufficient to operate electronic circuits.

Co-author Professor Vincenzo Pecunia, from Soochow University, said: "Our discovery opens up a whole new direction in the search for green, easy-to-make materials to sustainably power our smart devices.

"In addition to their eco-friendly nature, these materials could potentially be processed onto unconventional substrates such as plastics and fabric, which are incompatible with conventional technologies. Therefore, lead-free perovskite-inspired materials could soon enable battery-free devices for wearables, healthcare monitoring, smart homes, and smart cities."

The pursuit of ever-higher imaging resolution in microscopy is coupled with growing demands for compact portability and high throughput. While imaging performance has improved, conventional microscopes still suffer from the bulky, heavy elements and architectures associated with refractive optics. Metalenses offer a solution: they're ultrathin, ultralight, and flat, and benefit from lots of recent research that has improved their efficiency, FOV, and polarization functionalities.

According to Tao Li, professor of engineering and applied sciences at Nanjing University, "An ultra-compact metalens for imaging will miniaturize and even revolutionize conventional optical devices." Despite all the ongoing work to improve metalenses, most research groups are using them as a substitute for conventional refractive lenses in conventional optical settings. For metalenses to move toward real-world application, it's important to learn how to integrate metalenses into ultracompact optical devices.

In pursuit of a compact integrated microscope system, Li's team mounted a metalens on a CMOS image sensor to create a prototype of a coin-sized imaging device. As reported in Advanced Photonics, their metalens-integrated imaging device (MIID) exhibits an ultracompact architecture with a working imaging distance in the hundreds of micrometers. Using a simple image-stitching process, they are able to obtain wide-field microscope imaging with large FOV and high resolution.

Pocket microscope system

The MIID prototype involves a millimeter-sized silicon metalens in a well-designed array of 6x6. Despite the integration of multiple lenses, imaging distance remains relatively small (~500 μm) because each single lens is sized about 200 μm. According to the authors, it can be extended to centimeter scale to cover the whole CMOS sensor.

The metalens array, which is a polarization multiplexer, has two different phase profiles corresponding to two circular light polarizations. According to Li, this arrangement ensures the elimination of blind areas.

The authors hope that the new MIID prototype heralds a new era of the pocket microscope system. They acknowledge that the imaging performance needs improvement and suggest a variety of approaches, such as adopting low-loss materials like GaN and SiN. They anticipate continuing advances in microscopy based on meta-technology in the future.

Throughout the COVID-19 pandemic, political ideology has been perhaps the strongest predictor of consumers' perceptions of the coronavirus' threat. According to a new study from Lehigh University's College of Business, the differences between conservative and liberal responses to COVID-19 are mitigated when people perceive the virus itself to have agency -- the ability to control its own actions and thus exert power over people.

Conservatives are generally more sensitive to threats that are relatively high in agency, propose Daniel Zane, assistant professor of marketing in Lehigh University's College of Business, and co-author Luke Nowlan, assistant professor of marketing at KU Leuven, Belgium, in their study.

"In the context of the pandemic, you have these players -- the policymakers, the American public, media organizations, your neighbors - that, at least relative to the unobservable virus, have more agency," says Zane, "whereas this virus has less agency."

According to the paper, "Getting Conservatives and Liberals to Agree on the COVID-19 Threat," published in the Journal of the Association for Consumer Research in September, conservatives tend to see free will as the primary driver of outcomes in life, whereas liberals are more accepting of the idea that randomness plays a role. Compared to liberals, conservatives tend to attribute outcomes to purposeful actions. So in the context of the pandemic, they're more likely to blame any negative outcomes in their lives on these more agentic policymakers or fellow Americans rather than the virus itself.

"According to our study, conservatives might at least in part be less likely to wear masks because they don't feel as threatened by the virus itself," says Zane. "Any hardships that they're facing in their lives around health, financial issues, even going to movie theaters or shopping malls, might not necessarily trace back to the virus for them. So, they feel like they don't have to protect themselves from it."

To get greater buy-in about safety measures like wearing masks and economic shutdowns, Zane says that at the beginning of the pandemic, and even still now, instead of throwing around statistics, policymakers and health officials should have started talking about the virus in terms that gave it more agency.

"If they talked about the virus as having a motive, as being a palpable enemy that is seeking to attack humans," says Zane, "maybe you get greater buy-in from the start on the part of conservatives. We also show in our research that liberals are not driven away by doing this, so it seems like a good move."

ITHACA, N.Y. - The seeds of a teff plant - which look similar to wheat - are tiny in stature, but they pack a nutritional wallop.

Relatively new to the U.S., teff has long been a superfood in East African - specifically Ethiopia - as a staple food crop rich in fiber.

Cornell University food scientists, led by Elad Tako, associate professor of food science, now confirm this grain greatly helps the stomach and enhances the nutritional value of iron and zinc, according to a new modeling method. Their findings were reported Oct. 2 in the journal Nutrients.

Teff was tested in Cornell food science labs to understand how its seed extracts would affect the gastrointestinal tract and other systems in living organisms, via the utilization of a unique in vivo approach.

"The grain teff is extremely valuable," said Tako, the paper's senior author. "For the first time, we were able to associate teff-seed extracts and teff consumption with positive effects on the intestinal microbiome composition and function, potentially explaining why the prevalence of dietary iron and zinc deficiencies in Ethiopia - although still significant - are lower in comparison to other neighboring African nations."

Tako and his group conducted experiments while developing and using fertile eggs from the standard domesticated chicken (Gallus gallus). The embryonic phase of Gallus gallus lasts for 21 days, during which time the embryo is surrounded by amniotic fluid (egg whites), which is naturally and orally consumed by the embryo prior to hatch on day 21.

In the experiment, the teff seed fiber extract was injected into the fertile Gallus gallus eggs' amniotic fluid, which consists mostly of water and short peptides, on day 17 of embryonic development. The amniotic fluid and the added nutritional solution are then consumed by the embryo by day 19 of embryonic incubation.

"By utilizing this unique in vivo model and research approach, we are able to test how a candidate compound - in this case the teff grain extract - or solution affects the gastrointestinal tract, but also other systems or other tissues," Tako said. "We were able to confirm positive effects on the intestinal microbiome and duodenal (small intestine) functionality and tissue morphology."

Several important bacterial metabolic pathways were enriched by the teff extract, likely due to the grain's high relative fiber concentration, demonstrating an important bacterial-host interaction that contributes to improvements in the physiological status of iron and zinc, and the functionality of the intestinal digestive and absorptive surface.

"We're taking advantage of the embryonic phase, as a unique in vivo model to assess the potential nutritional benefits of plant origin bioactive compounds," said Tako, who is guest editor for an upcoming special issue of Nutrients, "Alleviating Zinc Dietary Deficiency, and Monitoring Poor Physiological Zinc Status in Sensitive Populations."

Deep learning is everywhere. This branch of artificial intelligence curates your social media and serves your Google search results. Soon, deep learning could also check your vitals or set your thermostat. MIT researchers have developed a system that could bring deep learning neural networks to new -- and much smaller -- places, like the tiny computer chips in wearable medical devices, household appliances, and the 250 billion other objects that constitute the "internet of things" (IoT).

The system, called MCUNet, designs compact neural networks that deliver unprecedented speed and accuracy for deep learning on IoT devices, despite limited memory and processing power. The technology could facilitate the expansion of the IoT universe while saving energy and improving data security.

The research will be presented at next month's Conference on Neural Information Processing Systems. The lead author is Ji Lin, a PhD student in Song Han's lab in MIT's Department of Electrical Engineering and Computer Science. Co-authors include Han and Yujun Lin of MIT, Wei-Ming Chen of MIT and National University Taiwan, and John Cohn and Chuang Gan of the MIT-IBM Watson AI Lab.

The Internet of Things

The IoT was born in the early 1980s. Grad students at Carnegie Mellon University, including Mike Kazar '78, connected a Cola-Cola machine to the internet. The group's motivation was simple: laziness. They wanted to use their computers to confirm the machine was stocked before trekking from their office to make a purchase. It was the world's first internet-connected appliance. "This was pretty much treated as the punchline of a joke," says Kazar, now a Microsoft engineer. "No one expected billions of devices on the internet."

Since that Coke machine, everyday objects have become increasingly networked into the growing IoT. That includes everything from wearable heart monitors to smart fridges that tell you when you're low on milk. IoT devices often run on microcontrollers -- simple computer chips with no operating system, minimal processing power, and less than one thousandth of the memory of a typical smartphone. So pattern-recognition tasks like deep learning are difficult to run locally on IoT devices. For complex analysis, IoT-collected data is often sent to the cloud, making it vulnerable to hacking.

"How do we deploy neural nets directly on these tiny devices? It's a new research area that's getting very hot," says Han. "Companies like Google and ARM are all working in this direction." Han is too.

With MCUNet, Han's group codesigned two components needed for "tiny deep learning" -- the operation of neural networks on microcontrollers. One component is TinyEngine, an inference engine that directs resource management, akin to an operating system. TinyEngine is optimized to run a particular neural network structure, which is selected by MCUNet's other component: TinyNAS, a neural architecture search algorithm.

System-algorithm codesign

Designing a deep network for microcontrollers isn't easy. Existing neural architecture search techniques start with a big pool of possible network structures based on a predefined template, then they gradually find the one with high accuracy and low cost. While the method works, it's not the most efficient. "It can work pretty well for GPUs or smartphones," says Lin. "But it's been difficult to directly apply these techniques to tiny microcontrollers, because they are too small."

So Lin developed TinyNAS, a neural architecture search method that creates custom-sized networks. "We have a lot of microcontrollers that come with different power capacities and different memory sizes," says Lin. "So we developed the algorithm [TinyNAS] to optimize the search space for different microcontrollers." The customized nature of TinyNAS means it can generate compact neural networks with the best possible performance for a given microcontroller -- with no unnecessary parameters. "Then we deliver the final, efficient model to the microcontroller," say Lin.

To run that tiny neural network, a microcontroller also needs a lean inference engine. A typical inference engine carries some dead weight -- instructions for tasks it may rarely run. The extra code poses no problem for a laptop or smartphone, but it could easily overwhelm a microcontroller. "It doesn't have off-chip memory, and it doesn't have a disk," says Han. "Everything put together is just one megabyte of flash, so we have to really carefully manage such a small resource." Cue TinyEngine.

The researchers developed their inference engine in conjunction with TinyNAS. TinyEngine generates the essential code necessary to run TinyNAS' customized neural network. Any deadweight code is discarded, which cuts down on compile-time. "We keep only what we need," says Han. "And since we designed the neural network, we know exactly what we need. That's the advantage of system-algorithm codesign." In the group's tests of TinyEngine, the size of the compiled binary code was between 1.9 and five times smaller than comparable microcontroller inference engines from Google and ARM. TinyEngine also contains innovations that reduce runtime, including in-place depth-wise convolution, which cuts peak memory usage nearly in half. After codesigning TinyNAS and TinyEngine, Han's team put MCUNet to the test.

MCUNet's first challenge was image classification. The researchers used the ImageNet database to train the system with labeled images, then to test its ability to classify novel ones. On a commercial microcontroller they tested, MCUNet successfully classified 70.7 percent of the novel images -- the previous state-of-the-art neural network and inference engine combo was just 54 percent accurate. "Even a 1 percent improvement is considered significant," says Lin. "So this is a giant leap for microcontroller settings."

The team found similar results in ImageNet tests of three other microcontrollers. And on both speed and accuracy, MCUNet beat the competition for audio and visual "wake-word" tasks, where a user initiates an interaction with a computer using vocal cues (think: "Hey, Siri") or simply by entering a room. The experiments highlight MCUNet's adaptability to numerous applications.

"Huge potential"

The promising test results give Han hope that it will become the new industry standard for microcontrollers. "It has huge potential," he says.

The advance "extends the frontier of deep neural network design even farther into the computational domain of small energy-efficient microcontrollers," says Kurt Keutzer, a computer scientist at the University of California at Berkeley, who was not involved in the work. He adds that MCUNet could "bring intelligent computer-vision capabilities to even the simplest kitchen appliances, or enable more intelligent motion sensors."

MCUNet could also make IoT devices more secure. "A key advantage is preserving privacy," says Han. "You don't need to transmit the data to the cloud."

Analyzing data locally reduces the risk of personal information being stolen -- including personal health data. Han envisions smart watches with MCUNet that don't just sense users' heartbeat, blood pressure, and oxygen levels, but also analyze and help them understand that information. MCUNet could also bring deep learning to IoT devices in vehicles and rural areas with limited internet access.

Plus, MCUNet's slim computing footprint translates into a slim carbon footprint. "Our big dream is for green AI," says Han, adding that training a large neural network can burn carbon equivalent to the lifetime emissions of five cars. MCUNet on a microcontroller would require a small fraction of that energy. "Our end goal is to enable efficient, tiny AI with less computational resources, less human resources, and less data," says Han.

Scientists using an instrument aboard NASA's Mars Atmosphere and Volatile EvolutioN, or MAVEN, spacecraft have discovered that water vapor near the surface of the Red Planet is lofted higher into the atmosphere than anyone expected was possible. There, it is easily destroyed by electrically charged gas particles -- or ions -- and lost to space.

Researchers said that the phenomenon they uncovered is one of several that has led Mars to lose the equivalent of a global ocean of water up to hundreds of feet (or up to hundreds of meters) deep over billions of years. Reporting on their finding on Nov. 13 in the journal Science, researchers said that Mars continues to lose water today as vapor is transported to high altitudes after sublimating from the frozen polar caps during warmer seasons.

"We were all surprised to find water so high in the atmosphere," said Shane W. Stone, a doctoral student in planetary science at the University of Arizona's Lunar and Planetary Laboratory in Tucson. "The measurements we used could have only come from MAVEN as it soars through the atmosphere of Mars, high above the planet's surface."

To make their discovery, Stone and his colleagues relied on data from MAVEN's Neutral Gas and Ion Mass Spectrometer (NGIMS), which was developed at NASA's Goddard Space Flight Center in Greenbelt, Maryland. The mass spectrometer inhales air and separates the ions that comprise it by their mass, which is how scientists identify them.

Stone and his team tracked the abundance of water ions high over Mars for more than two Martian years. In doing so, they determined that the amount of water vapor near the top of the atmosphere at about 93 miles, or 150 kilometers, above the surface is highest during summer in the southern hemisphere. During this time, the planet is closest to the Sun, and thus warmer, and dust storms are more likely to happen.

The warm summer temperatures and strong winds associated with dust storms help water vapor reach the uppermost parts of the atmosphere, where it can easily be broken into its constituent oxygen and hydrogen. The hydrogen and oxygen then escape to space. Previously, scientists thought that water vapor was trapped close to the Martian surface like it is on Earth.

"Everything that makes it up to the higher part of the atmosphere is destroyed, on Mars or on Earth," Stone said, "because this is the part of the atmosphere that is exposed to the full force of the Sun."

The researchers measured 20 times more water than usual over two days in June 2018, when a severe global dust storm enveloped Mars (the one that put NASA's Opportunity rover out of commission). Stone and his colleagues estimated Mars lost as much water in 45 days during this storm as it typically does throughout an entire Martian year, which lasts two Earth years.

"We have shown that dust storms interrupt the water cycle on Mars and push water molecules higher in the atmosphere, where chemical reactions can release their hydrogen atoms, which are then lost to space," said Paul Mahaffy, director of the Solar System Exploration Division at NASA Goddard and principal investigator of NGIMS.

Other scientists have also found that Martian dust storms can lift water vapor far above the surface. But nobody realized until now that the water would make it all the way to the top of the atmosphere. There are abundant ions in this region of the atmosphere that can break apart water molecules 10 times faster than they're destroyed at lower levels.

"What's unique about this discovery is that it provides us with a new pathway that we didn't think existed for water to escape the Martian environment," said Mehdi Benna, a Goddard planetary scientist and co-investigator of MAVEN's NGIMS instrument. "It will fundamentally change our estimates of how fast water is escaping today and how fast it escaped in the past."

When air quality worsens, either from the smoke and ozone of summer or the inversion of winter, most of us stay indoors. But for individuals experiencing homelessness, that's not always an option. In a new study, researchers from the University of Utah document the effect of air pollution on people experiencing homelessness, finding that nearly all notice and are impacted by air pollution, whether or not they reside in shelters.

The study, funded by the Interdisciplinary Exchange for Utah Science (NEXUS) at the University of Utah, is published in the International Journal of Environmental Research and Public Health.

Life lived outdoors

People experiencing homelessness, particularly those who sleep outdoors at night, are the most vulnerable and exposed population to environmental hazards, says Daniel Mendoza, a research assistant professor in the Department of Atmospheric Sciences and visiting assistant professor in the Department of City & Metropolitan Planning. Mendoza also holds appointments as an adjunct assistant professor in the Pulmonary Division in the School of Medicine and as a senior scientist at NEXUS. "Many individuals sleep near a road or under a bridge," he says, "which leads to exposure to high levels of traffic related emissions. Further compounding the issue is the fact that during sleep, many people breathe through their mouth and breathe more deeply."

This life lived outdoors makes homelessness an environmental justice issue, says Jeff Rose, assistant professor in the Department of Parks, Recreation and Tourism.

"People experiencing unsheltered homelessness often live, eat, sleep, socialize, use the bathroom, and other basic human functions outdoors, with close and regular interaction with the environment," he says. Environmental justice research looks at uneven exposures to pollution and other environmental risks. "Increasingly, scholars are considering people experiencing unsheltered homelessness as fitting in this framework."

While other researchers have looked at how people experiencing homelessness experience environmental injustice in the form of access to safe drinking water or parks, the U team says it is among the first to look at how people experiencing homelessness also experience the intermittent poor air quality of Salt Lake County.

Gathering experiences

To collect people's stories, Angelina DeMarco, a doctoral student in anthropology and Rebecca Hardenbrook, a doctoral student in mathematics, went to several Salt Lake City resource centers to meet with people experiencing sheltered homelessness.

"We sat in the dining hall of each center and invited all residents that came by to interview," DeMarco says. In partnership with the Volunteers of America outreach team, they also interviewed people at the Salt Lake City library, on downtown streets, outside the St. Vincent de Paul dining hall and at local parks. Outdoor interviews took place often during harsh winter conditions, DeMarco says.

They interviewed everyone they encountered, 138 people total, and asked them open-ended questions about when and how they knew the air was polluted, and how air pollution make them feel. With the interviewees' permission, the researchers also examined health records kept by the state Homeless Management Information System.

Sheltered and unsheltered

More than half of the participants reported having physical reactions to air pollution including headaches and difficulty breathing, and more than a third reported emotional stress associated with air pollution. 89% reported seeking medical treatment for their symptoms.

But the researchers also wanted to look at whether the duration of homelessness or residing within a shelter would affect individuals' experiences with air pollution. Surprisingly, they found no significant differences in heart and lung health outcomes between sheltered and unsheltered individuals, as well as between people experiencing chronic (more than a year) or non-chronic homelessness.

"These results indicate that sheltered and unsheltered, short-term and long-term homeless populations experience negative health outcomes that are associated with air pollution," DeMarco says. The mental health impacts of air pollution exposure, she says, merit additional study.

The message for governmental leaders, the researchers say, is that shelters and day centers that protect people from the elements may not be shielding them from air pollution and other environmental impacts, which can have a significant effect on their health. Affordable housing policies and efforts to place people experiencing homelessness in housing, they say, may do much more to protect a vulnerable population from an environmental hazard.

Plastic pollution is ubiquitous today, with microplastic particles from disposable goods found in natural environments throughout the globe, including Antarctica. But how those particles move through and accumulate in the environment is poorly understood. Now a Princeton University study has revealed the mechanism by which microplastics, like Styrofoam, and particulate pollutants are carried long distances through soil and other porous media, with implications for preventing the spread and accumulation of contaminants in food and water sources.

The study, published in Science Advances on November 13, reveals that microplastic particles get stuck when traveling through porous materials such as soil and sediment but later break free and often continue to move substantially further. Identifying this stop-and-restart process and the conditions that control it is new, said Sujit Datta, assistant professor of chemical and biological engineering and associated faculty of the Andlinger Center for Energy and the Environment, the High Meadows Environmental Institute and the Princeton Institute for the Science and Technology of Materials. Previously, researchers thought that when microparticles got stuck, they generally stayed there, which limited understanding of particle spread.

Datta led the research team, which found that the microparticles are pushed free when the rate of fluid flowing through the media remains high enough. The Princeton researchers showed that the process of deposition, or the formation of clogs, and erosion, their breakup, is cyclical; clogs form and then are broken up by fluid pressure over time and distance, moving particles further through the pore space until clogs reform.

"Not only did we find these cool dynamics of particles getting stuck, clogged, building up deposits and then getting pushed through, but that process enables particles to get spread out over much larger distances than we would have thought otherwise," said Datta.

The team included Navid Bizmark, a postdoctoral research associate in the Princeton Institute for the Science and Technology of Materials, graduate student Joanna Schneider, and Rodney Priestley, professor of chemical and biological engineering and vice dean for innovation.

They tested two types of particles, "sticky" and "nonsticky," which correspond with actual types of microplastics found in the environment. Surprisingly, they found that there was no difference in the process itself; that is, both still clogged and unclogged themselves at high enough fluid pressures. The only difference was where the clusters formed. The "nonsticky" particles tended to get stuck only at narrow passageways, whereas the sticky ones seemed to be able to get trapped at any surface of the solid medium they encountered. As a result of these dynamics, it is now clear that even "sticky" particles can spread out over large areas and throughout hundreds of pores.

In the paper, the researchers describe pumping fluorescent polystyrene microparticles and fluid through a transparent porous media developed in Datta's lab, and then watching the microparticles move under a microscope. Polystyrene is the plastic microparticle that makes up Styrofoam, which is often littered into soils and waterways through shipping materials and fast food containers. The porous media they created closely mimics the structure of naturally-occurring media, including soils, sediments, and groundwater aquifers.

Typically porous media are opaque, so one cannot see what microparticles are doing or how they flow. Researchers usually measure what goes in and out of the media, and try to infer the processes going on inside. By making transparent porous media, the researchers overcame that limitation.

"Datta and colleagues opened the black box," said Philippe Coussot, a professor at Ecole des Ponts Paris Tech and an expert in rheology who is unaffiliated with the study.

"We figured out tricks to make the media transparent. Then, by using fluorescent microparticles, we can watch their dynamics in real time using a microscope," said Datta. "The nice thing is that we can actually see what individual particles are doing under different experimental conditions."

The study, which Coussot described as a "remarkable experimental approach," showed that although the Styrofoam microparticles did get stuck at points, they ultimately were pushed free, and moved throughout the entire length of the media during the experiment.

The ultimate goal is to use these particle observations to improve parameters for larger scale models to predict the amount and location of contamination. The models would be based on varying types of porous media and varying particle sizes and chemistries, and help to more accurately predict contamination under various irrigation, rainfall, or ambient flow conditions. The research can help inform mathematical models to better understand the likelihood of a particle moving over a certain distance and reaching a vulnerable destination, such as a nearby farmland, river or aquifer. The researchers also studied how the deposition of microplastic particles impacts the permeability of the medium, including how easily water for irrigation can flow through soil when microparticles are present.

Datta said this experiment is the tip of the iceberg in terms of particles and applications that researchers can now study. "Now that we found something so surprising in a system so simple, we're excited to see what the implications are for more complex systems," said Datta.

He said, for example, this principle could yield insight into how clays, minerals, grains, quartz, viruses, microbes and other particles move in media with complex surface chemistries.

The knowledge will also help the researchers understand how to deploy engineered nanoparticles to remediate contaminated groundwater aquifers, perhaps leaked from a manufacturing plant, farm, or urban wastewater stream.

Beyond environmental remediation, the findings are applicable to processes across a spectrum of industries, from drug delivery to filtration mechanisms, effectively any media in which particles flow and accumulate, Datta said.

What The Study Did: This randomized trial compares the effects of fluvoxamine, a selective serotonin reuptake inhibitor with immunomodulatory effects, versus placebo on a composite of dyspnea or pneumonia and oxygen desaturation among adult outpatients with polymerase chain reaction-confirmed mild COVID-19 illness.

Authors: Eric J. Lenze, M.D., of the Washington University School of Medicine in St. Louis, is the corresponding author.

To access the embargoed study: Visit our For The Media website at this link https://media.jamanetwork.com/

(doi:10.1001/jama.2020.22760)

Editor's Note: The article includes conflict of interest and funding/support disclosures. Please see the article for additional information, including other authors, author contributions and affiliations, conflict of interest and financial disclosures, and funding and support.

Researchers from Kumamoto University (Japan) have developed a system to quickly and easily measure the antioxidant capacity of food. The new electrochemical system uses a gel form Bicontinuous Microemulsion (BME), a mixture of water and oil that do not normally mix, integrated with a sheet-type electrode. This system can easily be used by anyone anywhere and is expected to be used for quality control in the production, manufacturing and sale of food products.

Some of the oxygen taken into the body is converted into highly reactive oxygen species (ROS). Excessive production of ROS can lead to arteriosclerosis, cancer, aging, and decreased immune function. Antioxidants inhibit the generation of ROS and their function, or can even remove ROS themselves. Fat-soluble antioxidants, such as vitamins and polyphenols, are easily soluble in oil rather than water. It is important to evaluate the antioxidant capacity of food to maintain a healthy diet, but conventional evaluation methods require complex separation, extraction, and colorimetric analysis, which makes it difficult to measure fat-soluble antioxidants in colorful or cloudy food samples.

Professor Masashi Kunitake's research group has developed a new electrochemical system that allows easy measurement of antioxidant capacity anywhere. This was achieved by creating a new BME gel and integrating it with sheet electrodes to significantly simplify the measurement process.

Normally, an electrochemical analysis is taken by dissolving a sample into an electrolyte solution and measuring the currents from three electrodes (working, reference, & counter). In the new system, however, the gel membrane affixed to the electrodes acts as its own electrolyte solution. Even oily substances that are not soluble can be analyzed in their original state without separation and extraction. The system's electrodes are simply dipped into the sample or a drop of the sample is placed on the electrode—no extensive equipment or special treatment required. The antioxidant capacity of the sample can now be easily assessed without the complexities previously performed in the laboratory. This system has already been used to measure vitamin E in commercial olive oil as proof of concept.

"Our system can be used for quality control of meat, fish, vegetables, fruits, chocolate, cosmetics, and other products at production, manufacturing, and retail outlets," said Professor Kunitake. "If the analysis of food products becomes more accessible to producers and consumers, it could give added value to food products, help find the best cultivation conditions for production, and eventually become a criterion for judging whether food products are both tasty and safe to eat. We hope that this system will contribute to increased healthy food production for society."

The quest for high throughput intelligent computing paradigms - for big data and artificial intelligence - and the ever-increasing volume of digital information has led to an intensified demand for high-speed and low-power consuming next-generation electronic devices. The "forgotten" world of antiferromagnets (AFM), a class of magnetic materials, offers promise in future electronic device development and complements present-day ferromagnet-based spintronic technologies (Fig. 1).

Formidable challenges for AFM-based functional spintronic device development are high-speed electrical manipulation (recording), detection (retrieval), and ensuring the stability of the recorded information - all in a semiconductor industry-friendly material system.

Researchers at Tohoku University, University of New South Wales (Australia), ETH Zürich (Switzerland), and Diamond Light Source (United Kingdom) successfully demonstrated current-induced switching in a polycrystalline metallic antiferromagnetic heterostructure with high thermal stability. The established findings show potential for information storage and processing technologies.

The research group used a Mn-based metallic AFM (PtMn)/heavy metal (HM) heterostructure - attractive because of its significant antiferromagnetic anisotropy and its compatibility with PtMn Silicon-based electronics (Fig. 2(a)). Electrical recording of resistance states (1 or 0) was obtained through the spin-orbit interaction of the HM layer; a charge current in the adjacent HM resulted in spin-orbit torques acting on the AFM, leading to a change in the resistance level down to a microsecond regime (Fig. 2(b)).

"Interestingly, the switching degree is controllable by the strength of the current in the HM layer and shows long-term data retention capabilities," said Samik DuttaGupta, corresponding author of the study (Fig. 2(c)). "The experimental results from electrical measurements were supplemented by a magnetic X-ray imaging, helping to clarify the reversible nature of switching dynamics localized within nm-sized AFM domains." (Fig. 2(d),(e)).

The results are the first demonstration of current-induced switching of an industry-compatible AFM down to the microsecond regime within the field of metallic antiferromagnetic spintronics. These findings are expected to initiate new avenues for research and encourage further investigations towards the realization of functional devices using metallic AFMs for information storage and processing technologies.

When you cool down liquid water, it crystallizes into ice. Consider a bucket filled with water, for example. When the water is liquid, the water molecules can be anywhere inside the bucket. In this sense, every point inside the bucket is equivalent. Once the water freezes, however, the water molecules occupy well-defined positions in space. Thus, not every point inside the bucket is equivalent anymore. Physicists refer to this phenomenon as spontaneous symmetry breaking. Here the translation symmetry in space is broken by the formation of the crystal.

Is it possible for crystals to form in time instead of space? While it appears like an outlandish notion, it turns out that a time crystal may emerge when a physical system of many interacting particles is periodically driven. The defining feature of a time crystal is that a macroscopic observable, such as the electric current in a solid, oscillates at a frequency that is smaller than the driving frequency.

So far, time crystals have been realized in artificial model systems. But now, what about real systems? A piece of a high-temperature superconductor is such a real system - you can buy it online. It is not much to look at, with its brownish, rusty color. Yet its frictionless electron flow at temperatures up to 100 K ( 173 °C) constitutes one of the most spectacular phenomena of material science.

"We propose to turn a high-temperature superconductor into a time crystal by shining a laser on it", explains first author Guido Homann from the Department of Physics at Universität Hamburg. The frequency of the laser needs to be tuned to the sum resonance of two fundamental excitations of the material. One of these excitations is the elusive Higgs mode, which is conceptually related to the Higgs boson in particle physics. The other excitation is the plasma mode, corresponding to an oscillatory motion of electron pairs, which are responsible for superconductivity.

Co-author Dr. Jayson Cosme from Universität Hamburg, now University of the Philippines, adds that "the creation of a time crystal in a high-temperature superconductor is an important step because it establishes this genuine dynamical phase of matter in the domain of solid-state physics". Controlling solids by light is not only fascinating from a scientific perspective but also technologically relevant, as emphasized by group leader Prof. Dr. Ludwig Mathey. "The ultimate goal of our research is to design quantum materials on demand." With their novel proposal, this fascinating endeavor is now advanced towards dynamical states of matter, rather than the usual static states of matter, by laying out a strategy to design time crystals instead of regular crystals, which opens up a new and surprising direction of material design.

Small electronic circuits power our everyday lives, from the tiny cameras in our phones to the microprocessors in our computers. To make those devices even smaller, scientists and engineers are designing circuitry components out of single molecules. Not only could miniaturized circuits offer the benefits of increased device density, speed, and energy efficiency -- for example in flexible electronics or in data storage -- but harnessing the physical properties of specific molecules could lead to devices with unique functionalities. However, developing practical nanoelectronic devices from single molecules requires precise control over the electronic behavior of those molecules, and a reliable method by which to fabricate them.

Now, as reported in the journal Nature Electronics, researchers have developed a method to fabricate a one-dimensional array of individual molecules and to precisely control its electronic structure. By carefully tuning the voltage applied to a chain of molecules embedded in a one-dimensional carbon (graphene) layer, the team led by researchers at Lawrence Berkeley National Laboratory (Berkeley Lab) found they could control whether all, none, or some of the molecules carry an electric charge. The resulting charge pattern could then be shifted along the chain by manipulating individual molecules at the end of the chain.

"If you're going to build electrical devices out of individual molecules, you need molecules that have useful functionality and you need to figure out how to arrange them in a useful pattern. We did both of those things in this work," said Michael Crommie, a senior faculty scientist in Berkeley Lab's Materials Sciences Division, who led the project. The research is part of a U.S. Department of Energy (DOE) Office of Science-funded program on Characterization of Functional Nanomachines, whose overarching goal is to understand the electrical and mechanical properties of molecular nanostructures, and to create new molecule-based nanomachines capable of converting energy from one form to another at the nanoscale.

The key trait of the fluorine-rich molecule selected by the Berkeley Lab team is its strong tendency to accept electrons. To control the electronic properties of a precisely-aligned chain of 15 such molecules deposited on a graphene substrate, Crommie, who is also a UC Berkeley professor of physics, and his colleagues placed a metallic electrode underneath the graphene that was also separated from it by a thin insulating layer. Applying a voltage between the molecules and the electrode drives electrons into or out of the molecules. In that way, the graphene-supported molecules behave somewhat like a capacitor, an electrical component used in a circuit to store and release charge. But, unlike a "normal" macroscopic capacitor, by tuning the voltage on the bottom electrode the researchers could control which molecules became charged and which remained neutral.

In previous studies of molecular assemblies, the molecules' electronic properties could not be both tuned and imaged at atomic length scales. Without the additional imaging capability the relationship between structure and function can not be fully understood in the context of electrical devices. By placing the molecules in a specially-designed template on the graphene substrate developed at Berkeley Lab's Molecular Foundry nanoscale science user facility, Crommie and his colleagues ensured that the molecules were completely accessible to both microscope observation and electrical manipulation.

As expected, applying a strong positive voltage to the metallic electrode underneath the graphene supporting the molecules filled them with electrons, leaving the entire molecular array in a negatively charged state. Removing or reversing that voltage caused all the added electrons to leave the molecules, returning the entire array to a charge neutral state. At an intermediate voltage, however, electrons fill only every other molecule in the array, thus creating a "checkerboard" pattern of charge. Crommie and his team explain this novel behavior by the fact that electrons repel each other. If two charged molecules were to momentarily occupy adjacent sites, then their repulsion would push one of the electrons away and force it to settle one site further down the molecular row.

"We can make all the molecules empty of charge, or all full, or alternating. We call that a collective charge pattern because it's determined by electron-electron repulsion throughout the structure," said Crommie.

Calculations suggested that in an array of molecules with alternating charges the terminal molecule in the array should always contain one extra electron since that molecule does not have a second neighbor to cause repulsion. In order to experimentally investigate this type of behavior, the Berkeley Lab team removed the final molecule in an array of molecules that had alternating charges. They found that the original charge pattern had shifted over by one molecule: sites that had been charged became neutral and vice versa. The researchers concluded that before the charged terminal molecule was removed, the molecule adjacent to it must have been neutral. In its new position at the end of the array, the formerly second molecule then became charged. To maintain the alternating pattern between charged and uncharged molecules, the entire charge pattern had to shift by one molecule.

If the charge of each molecule is thought of as a bit of information, then removing the final molecule causes the entire pattern of information to shift by one position. That behavior mimics an electronic shift register in a digital circuit and provides new possibilities for transmitting information from one region of a molecular device to another. Moving a molecule at one end of the array could serve as flipping a switch on or off somewhere else in the device, providing useful functionality for a future logic circuit.

"One thing that we found really interesting about this result is that we were able to alter the electronic charge and therefore the properties of molecules from very far away. That level of control is something new," said Crommie.

With their molecular array the researchers achieved the goal of creating a structure that has very specific functionality; that is, a structure whose molecular charges may be finely tuned between different possible states by applying a voltage. Changing the charge of the molecules causes a change in their electronic behavior and, as a result, in the functionality of the entire device. This work came out of a DOE effort to construct precise molecular nanostructures that have well-defined electromechanical functionality.

The Berkeley Lab team's technique for controlling molecular charge patterns could lead to new designs for nanoscale electronic components including transistors and logic gates. The technique could also be generalized to other materials and incorporated into more complex molecular networks. One possibility is to tune the molecules to create more complex charge patterns. For example, replacing one atom with another in a molecule can change the molecule's properties. Placing such altered molecules in the array could create new functionality. Based on these results the researchers plan to explore the functionality that arises from new variations within molecular arrays, as well as how they can potentially be used as tiny circuit components. Ultimately, they plan to incorporate these structures into more practical nanoscale devices.