Tech

A research team led by professors from the University of Pittsburgh Department of Physics and Astronomy has announced the discovery of a new electronic state of matter.

Jeremy Levy, a distinguished professor of condensed matter physics, and Patrick Irvin, a research associate professor are coauthors of the paper "Pascal conductance series in ballistic one-dimensional LaAIO3/SrTiO3 channels." The research focuses on measurements in one-dimensional conducting systems where electrons are found to travel without scattering in groups of two or more at a time, rather than individually.

The study was published in Science on Feb. 14. A video outlining the paper's findings can be seen here: https://www.youtube.com/watch?v=kDjGiH8OnqU&feature=youtu.be

"Normally, electrons in semiconductors or metals move and scatter, and eventually drift in one direction if you apply a voltage. But in ballistic conductors the electrons move more like cars on a highway. The advantage of that is they don't give off heat and may be used in ways that are quite different from ordinary electronics. Researchers before us have succeeded in creating this kind of ballistic conductor," explained Levy.

"The discovery we made shows that when electrons can be made to attract one another, they can form bunches of two, three, four and five electrons that literally behave like new types of particles, new forms of electronic matter."

Levy compared the finding to the way in which quarks bind together to form neutrons and protons. An important clue to uncovering the new matter was recognizing that these ballistic conductors matched a sequence within Pascal's Triangle.

"If you look along different directions of Pascal's Triangle you can see different number patterns and one of the patterns was one, three, six, 10, 15, 21. This is a sequence we noticed in our data ,so it became a challenging clue as to what was actually going on. The discovery took us some time to understand but it was because we initially did not realize we were looking at particles made up of one electron, two electrons, three electrons and so forth. If you combine all this together you get the sequence of 1,3,6,10."

Levy, who is also director of the Pittsburgh Quantum Institute, noted that the new particles feature properties related to quantum entanglement, which can potentially be used for quantum computing and quantum redistribution. He said the discovery is an exciting advancement toward the next stage of quantum physics.

"This research falls within a larger effort here in Pittsburgh to develop new science and technologies related to the second quantum revolution," he said.

"In the first quantum revolution people discovered the world around them was governed fundamentally by laws of quantum physics. That discovery led to an understanding of the periodic table, how materials behave and helped in the development of transistors, computers, MRI scanners and information technology.

"Now in the 21st century, we're looking at all the strange predictions of quantum physics and turning them around and using them. When you talk about applications, we're thinking about quantum computing, quantum teleportation, quantum communications, quantum sensing--ideas that use properties of the quantum nature of matter that were ignored before."

Even under modest climate warming scenarios, the continental United States faces a significant loss of groundwater - about 119 million cubic meters, or roughly enough to fill Lake Powell four times or one quarter of Lake Erie, a first-of-its-kind study has shown.

The results, published today in Nature Communications, show that as warming temperatures shift the balance between water supply and demand, shallow groundwater storage can buffer plant water stress - but only where shallow groundwater connections are present, and not indefinitely. As warming persists, that storage can be depleted - at the expense of vital connections between surface water, such as rivers, streams and water reservoirs underground.

"Even with a 1.5 degrees Celsius warming case, we're likely to lose a lot of groundwater," said Reed Maxwell, professor of hydrology at the Colorado School of Mines, who co-authored the paper with Laura Condon of the University of Arizona and Adam Atchley of Los Alamos National Laboratory. "The East Coast could start looking like the West Coast from a water standpoint. That's going to be a real challenge."

Most global circulation models don't take into account the lateral movement of water in the subsurface. Typically, they only include limited up-and-down movement, such as rain percolating from vegetation into the soil and roots pulling up water from the ground. In addition, these models tend to limit their scope to mere meters above or below ground.

This new study goes beyond that to simulate how water moves in the subsurface and connects with the land surface.

"We asked what would the response look like if we included the entire complexity of subsurface water movement in a large-scale simulation, and we think this is the first time this has been done," said Condon, lead author of the paper and assistant professor of hydrology and atmospheric sciences at the University of Arizona.

The calculations revealed a direct response of shallow groundwater storage to warming that demonstrates the strong and early effect that even low to moderate warming may have on groundwater storage and evapotranspiration.

In the western U.S., changes in groundwater storage may remain masked for a long time, the study revealed, because the groundwater there is already deep, and dropping levels would not have as great an effect on surface waters. Additionally, the region's vegetation is already largely water limited and adapted to being disconnected from deep groundwater sources.

However, the eastern U.S. will be much more sensitive to a lowering of the water table. Groundwater and surface water are more closely linked, and depleting the groundwater will be more disruptive to vegetation, streams and rivers. Many of the systems that have been put in place in the western U.S. for handling and managing water shortage are lacking in the eastern part of the country, as well.

The study revealed that regions in the eastern U.S. may reach a tipping point sooner rather than later, when vegetation starts to lose access to shallow groundwater as storage is depleted with warming.

"Initially, plants might not be experiencing stress because they still have existing shallow groundwater available, but as we continue to have warmer conditions, they can compensate less and less, and changes are more dramatic each year," Condon said. "In other words, shallow groundwater is buffering the response to warming, but when it's depleted, it can't do that anymore."

The study's simulations were set up to keep precipitation patterns the same and only increase atmospheric temperatures according to projections ranging from 1.5 to 4 degrees Celsius. Even with a modest 1.5 degrees Celsius of warming, 119 million cubic meters of storage were lost from groundwater - or four times the volume of Lake Powell, the largest reservoir in the Upper Colorado basin. At 4 degrees Celsius, groundwater losses were projected at 324 million cubic meters - roughly 10 times the volume of Lake Powell or enough to fill nearly three-quarters of Lake Erie.

"We are facing a crisis in global groundwater storage," Condon said. "Huge groundwater reservoirs are drying up at an alarming rate, and that's a problem because they nourish major growing regions around the world."

Biosensors integrated into smartphones, smart watches, and other gadgets are about to become a reality. In a paper featured on the cover of the January issue of Sensors, researchers from the Moscow Institute of Physics and Technology describe a way to increase the sensitivity of biological detectors to the point where they can be used in mobile and wearable devices. The study was supported by the Russian Science Foundation.

A biosensor is an electrochemical device that determines the composition of biological fluids in real- time. Blood glucose meters used by diabetic patients may well be the only mass-market biosensing devices in use today. But futurologists say household appliances will soon be able to analyze sweat, saliva, aqueous humor, and other bodily fluids to identify a person, make medical tests, diagnose disease, or continuously monitor the health of an individual and make optimal diet suggestions accordingly.

Until recently, such applications were not seriously considered, because the available devices were not sensitive enough and were prohibitively expensive for the consumer market. However, it may be that a breakthrough is about to happen. A team of researchers from the MIPT Center for Photonics and 2D Materials has proposed a radically new biosensor design, which could increase detector sensitivity many times over and offer a similarly impressive reduction in price.

"A conventional biosensor incorporates a ring resonator and a waveguide positioned in the same plane," explained MIPT graduate student Kirill Voronin from the Laboratory of Nanooptics and Plasmonics, who came up with the idea used in the study. "We decided to separate the two elements and put them in two different planes, with the ring above the waveguide."

The reason researchers did not test that sensor layout before is that manufacturing a flat, single-level device is easier in a laboratory setting. By depositing a thin film and etching it, both a ring resonator and a waveguide are produced at the same time. The alternative two-level design is less convenient for manufacturing unique experimental devices, but it turned out cheaper for mass-producing sensors. The reason for this is that the technological processes at an electronics plant are geared toward layer-by-layer active component placement.

More importantly, the new two-tier biosensor design resulted in a many times higher sensitivity.

A biosensor operates by registering the slight changes in the refractive index at its surface, which are caused by organic molecule adsorption. These variations are detected via a resonator whose resonance conditions depend on the refractive index of the external medium. Since even the slightest fluctuations in the refractive index cause a significant resonant peak shift, a biosensor responds to nearly every molecule that lands on its surface.

"We have positioned the strip waveguide under the resonator, in the bulk dielectric," said paper co-author Aleksey Arsenin, a leading researcher at the MIPT Laboratory of Nanooptics and Plasmonics. "The resonator, in turn, is at the interface between the dielectric substrate and the external environment. By optimizing the refractive indices of the two surrounding media, we achieve a significantly higher sensitivity."

The newly proposed biosensor layout has both the source and the detector of light within the dielectric. The only part that remains on the outside is the sensitive element. That is, the gold ring several dozen micrometers in diameter and one-thousandth that in thickness (fig. 1).

According to Voronin, the team's method for making biosensors more responsive will take the technology to a qualitatively new level. "The new layout is intended to make biosensors much easier to manufacture, and therefore cheaper," the physicist said. "Optical lithography is the only technique necessary to produce detectors based on our principle. No moving parts are involved, and a tunable laser operating in a tight frequency range will suffice."

Valentyn Volkov, who heads the MIPT Center for Photonics and 2D Materials, estimates that it will take about three years to develop an industrial design based on the proposed technology.

An interdisciplinary team of bio-engineers and economists from KU Leuven has mapped out how wood could replace petroleum in the chemical industry. They not only looked at the technological requirements, but also whether that scenario would be financially viable. A shift from petroleum to wood would lead to a reduction in CO2 emissions, the researchers state in Science.

Our plastics, cleaning agents and building materials are usually made from chemical components derived from petroleum, rather than from renewable materials. Petroleum is currently cheaper to use as a raw material. But that doesn't have to be the case. The team of researchers previously published on how wood can be transformed into chemicals that can be used in a plethora of products. That process has now been fully mapped out. Moreover, they calculated that it can be financially feasible to build and run a biorefinery that converts wood into chemical building blocks.

To extract chemicals from wood, it is first split into a solid paper pulp and a liquid lignin oil. The pulp can be used to produce second generation biofuels or natural insulation, while the lignin oil, like petroleum oil, can be further processed to manufacture chemical building blocks, such as phenol, propylene, and components to create ink. The lignin can also be used to make alternative building blocks for plastics. Chemical compounds based on lignin are less harmful to humans, compared to those made out of petroleum.

"In the paper industry, lignin is seen as a residual product and usually burned. That's a pity, since just like petroleum, it can have many high quality uses if it can be properly separated from wood and the right chemical building blocks are extracted," explains Professor Bert Sels of the Department of Microbial and Molecular Systems. As a result, wood could replace petroleum in the chemical industry.

The new publication is an important milestone in the team's long-term research. "What's so special about this study is that we calculated the economic viability of a switch from petroleum to wood," says Bert Sels. To create a realistic scenario, the researchers joined forces with a Belgian-Japanese ink company. This is because certain compounds from lignin can be used to make ink. The calculations indicate that a chemical plant that uses wood as a raw material can be profitable after a few years.

CO2 storage

Through smart forest management, wood can be harvested sustainably. "Moreover, as a result of the shrinking paper industry, there is currently a surplus of wood in Europe", Sels explains. The researchers are also collaborating with waste processors and landscape managers to use prunings and other waste wood.

The environmental cost of using wood would be smaller than when using petroleum, since chemical compounds made from wood cause less CO2 emissions. Moreover, products made from wood derivatives can store CO2, just like trees do. "As a result, it would be possible to store carbon from CO2 in plastics - preferably recyclable ones," Sels said.

To demonstrate the application of their research, the team will now scale up the production process. The first test phase has already started. Ultimately, they want to create a wood biorefinery in Belgium. In the meantime, the researchers are in conversation with various business partners who can process the cellulose pulp and lignin oil in a variety of products.

"The chemical sector emits a lot of CO2 globally. A serious change is needed to achieve a carbon neutral chemistry," says Bert Lagrain, Sustainable Chemistry Innovation Manager. "By scaling up our research project, we hope to get the industry on board."

Researchers at Texas Heart Institute (THI) and UCLA crossed a significant milestone in the development of wirelessly powered, leadless pacemakers. In an article in the Nature Research journal Scientific Reports, the team used their innovative pacing system to reveal the ability to provide synchronized biventricular pacing to a human-sized heart in a preclinical research model.

Led by Dr. Mehdi Razavi, Director of Electrophysiology Clinical Research & Innovations at THI and Associate Professor at Baylor College of Medicine and Prof. Aydin Babakhani, Director of UCLA Integrated Sensors Laboratory, the research explores technology that could give doctors an entirely new therapeutic option for treating patients with arrhythmias and other cardiovascular comorbidities or conditions such as heart failure.

Approximately 30% of patients with chronic heart failure also have electrical conduction problems in their heart that require a type of therapy to resynchronize the heart's conduction system in its two largest chambers. In these cases, doctors prescribe cardiac resynchronization therapy or CRT. CRT is delivered by long wires, called leads, that are attached to pacemakers to pace both of the bottom chambers of the heart. When a patient needs both chambers of the heart synchronized, called biventricular pacing, a traditional pacemaker with leads is currently the only commercially available option. Unfortunately, these leads are prone to fracturing, dislodging, and migrating away from the original location.

Although patients do see improvements with CRT, usually within 6 months, roughly a third of patients do not respond well to the therapy, and non-responder rates can be as high as 43%.

By allowing simultaneous pacing from multiple sites in the heart, THI and UCLA's new leadless, wirelessly powered pacemaker system aims to reduce the complications associated with the traditional pacemakers in use today and opens the door for safer and more effective biventricular pacing options.

Previous research by the team proved the system's ability to wirelessly power a single site in the hearts of small, medium, and large open-chest research models. In the new study, the tiny pacemakers--only a fraction of the size of a quarter --were shown to work in a closed-chest porcine model via wireless powered transfer to custom-designed low power integrated circuits on the heart.

The pacemaker's potential clinical benefit, verified through measurements of electrical activity with an EKG and blood flow in the heart during the testing, was impressive. Specifically, the biventricular pacing strategy improved important clinical outcomes measures when compared to single-chamber pacing. Overall, the results advance the possibility of using wirelessly powered, multisite pacing to address cardiac resynchronization challenges.

The team is currently working on further miniaturizing the wirelessly powered pacemaker to make it implantable at one or more desired pacing sites on the heart in a minimally invasive manner. This will eliminate the need for intravascular leads and, most importantly, allow for synchronized and leadless pacing across multiple chambers of the heart, which offers the ability to provide patient-specific CRT.

A significant challenge of this new technology is maintaining the efficiency of wireless power transfer as the device becomes very small and the antenna becomes less efficient. The team addressed this issue by significantly lowering the power consumption of the electronics used in the pacemaker, integrating all the elements on a single chip, and designing antennas that resonate strongly with the input circuitry of the pacing chips, according to Prof. Babakhani, an associate professor of electrical and computer engineering at UCLA Samueli School of Engineering.

Babakhani's laboratory, funded by UCLA, has pushed the limits of miniaturization so that an entire pacemaker can fit inside a vein. The miniaturized pacemaker eliminates the need for bulky onboard batteries as it receives energy and commands wirelessly through electromagnetic waves from an external controller.

The pacing device is based on silicon-based integrated microchips that were built in Prof. Babakhani's laboratory at UCLA. Postdoctoral scholar Hongming Lyu and Ph.D. students, Hamed Rahmani and Yuxiang Sun of Prof. Babakhani's laboratory at UCLA designed the earlier version of the device.

"Miniaturized implantable medical devices are already on the market today. They are used in neural implants, in microchips that can be wirelessly programmed to deliver doses of osteoporosis drugs, and in disposable video capsules that can be swallowed to wirelessly transmit images of the GI tract while traveling through the body. So why not miniaturize the pacemaker?" stated Dr. Razavi.

The team's ultimate goal is to build a pacing system that can diagnose the pacing needs of the heart in real-time, provide critical feedback to the care team if needed, and deliver tailored treatments. Thus, the pacemaker will eventually be able to harness the power of artificial intelligence (A.I.) by learning from the data it generates to identify patterns and make adjustments. This A.I. capability could ensure constant, optimal patient-specific therapy according to THI research engineers, Dr. Allison Post and Mathews John. THI and UCLA are already collaborating with Rice University on the algorithms to accomplish this goal. Although this was not part of the research published in the Scientific Reports article, the Rice research team participated in the study discussions.

"We are creating a smart pacemaker that will constantly read the heart's electrical needs and self-correct or continuously adjust and recalibrate to deliver a personalized pacing treatment in real-time, for each individual," added Dr. Razavi.

Dr. Abdi Rasekh, an electrophysiologist, and cardiologist with the THI Electrophysiology Clinical Research & Innovations team said the continued investment in robust research infrastructure has allowed the team to form productive collaborations and attract talented engineers, and cardiologists. "We have a highly supportive environment for developing innovative cardiac arrhythmia management solutions that could significantly improve quality of life, "added Dr. Rasekh.

ATHENS, Ohio (Feb. 13, 2020) - Researchers at Ohio University have published a new study in collaboration with Ugandan scientists, cautioning that humans place endangered mountain gorillas at risk of disease transmission during tourism encounters.

Mountain gorillas (Gorilla beringei beringei) are an endangered species of great ape found only in eastern Africa. Over 40% of the 1,059 mountain gorillas that remain on the planet today reside in Bwindi Impenetrable National Park in southwestern Uganda, and these apes are the heart of a growing tourism industry that has incentivized their continued protection. But close proximity between humans and gorillas during tourism encounters presents well-documented risks for disease transmission.

Gorillas are particularly susceptible to infectious diseases that affect humans, and respiratory infections are the most common, causing up to 20% of sudden deaths in gorillas. Accordingly, the Uganda Wildlife Authority has developed rules to protect the health of the gorillas, limiting each habituated gorilla group to a single hour-long visit per day by a group of no more than eight tourists. Current rules emphasize that humans must maintain a seven-meter (or greater) distance from gorillas at all times, which in the absence of wind is the minimum safe distance to avoid a sneezed droplet carrying infectious particles.

A number of studies over the years have documented that not all tour groups respect the seven-meter rule.

In a new study published in Frontiers in Public Health, Ohio University researchers documented tourist-gorilla spacing during 53 gorilla treks during a recent tourism high season in Bwindi Impenetrable National Park. They report that although 96% of pre-trek briefings conducted by park rangers emphasized the need to maintain greater than seven-meter human-gorilla spacing, the seven-meter distance rule was violated in over 98% (52 out of 53) of the tours examined in the study. Using observational data collected at two-minute intervals during gorilla-viewing tourism encounters, the researchers documented that nearly 70% of all observations took place at a distance less than or equal to seven meters.

"Although I had heard tourists were getting too close to the gorillas, I was surprised by the extent of the problem," observed study co-author Annalisa Weber, a graduate student in the Environmental Studies Program at Ohio University when the research was conducted, and now a senior research associate at Emory University. "We found that seven-meter rule was violated in visits to all of the gorilla groups habituated at the time of the study. And in 14% of observations, human-gorilla spacing was three meters or less."

"This points to a growing pattern of risk that is a cause of concern to sustaining long term gorilla-viewing tourism," noted Dr. Gladys Kalema-Zikusoka, CEO of Conservation Through Public Health and a co-author on the study. "Action is needed to limit disease risks caused by tourists viewing mountain gorillas."

Importantly, the researchers also explored opportunities to improve tourist adherence to park rules. For example, over 73% of the 243 tourists surveyed in the study responded that that they would be willing to utilize precautionary measures to protect gorilla health, for example in wearing protective face masks during viewing encounters. Indeed, wearing masks is considered best practice among scientists working in primate conservation, and this measure is already in place in The Democratic Republic of the Congo, where tourists regularly wear protective face masks during gorilla tourism encounters.

The use of protective masks could have logistical and financial limitations, and the researchers urge that the best strategy is to encourage tourists to maintain a safe distance from gorillas. "As tourism increases, and gorillas become increasingly habituated to human presence, new strategies will be needed for endangered great ape populations to thrive into the future," observed Dr. Nancy Stevens, Professor in the Department of Biomedical Sciences in the Heritage College of Osteopathic Medicine at Ohio University and corresponding author on the study. "Fortunately, we have talked with many insightful and empowered park officials who are poised to take action to protect gorilla health."

PROVIDENCE, R.I. [Brown University] -- A new study reveals good news for the possibility of using perovskite materials in next-generation solar cells.

The study, published in the journal Acta Materialia, finds that though perovskite films tend to crack easily, those cracks are easily healed with some compression or a little bit of heat. That bodes well, the researchers say, for the use of inexpensive perovskites to replace or complement pricy silicon in solar cell technologies.

"The efficiency of perovskite solar cells has grown very quickly and now rivals silicon in laboratory cells," said Nitin Padture, the Otis E. Randall Professor in Brown's School of Engineering and director of Brown's Institute for Molecular and Nanoscale Innovation. "Everybody's chasing high efficiency, which is important, but we also need to be thinking about things like long-term durability and mechanical reliability if we're going to bring this solar cell technology to the market. That's what this research was about."

Perovskites, a broad class of crystalline materials, were first incorporated into solar cells in 2009. Those first perovskite solar cells had a power conversion efficiency of around 4%, but now that exceeds 25% -- essentially the same as traditional silicon. The advantage of perovskite solar cells is that they can be made for a fraction of the cost of silicon, potentially cutting the cost of solar power installations. Perovskites can also be made into thin films that are semi-transparent and flexible, potentially clearing the way for energy-generating windows or for lightweight, flexible solar cells in tents or backpacks.

But the low-cost and ease of making perovskite solar cells comes with a cost.

"In material science, things that are easy to make also tend to be easy to break," said Padture who led the study. "That's certainly true of perovskites, which are quite brittle. But here we show they're also quite easy to fix -- cracks in perovskite films can be healed by compressing them or with moderate heat."

For the study, Srinivas Yadavalli, a doctoral student working in Padture's laboratory and the first author of the paper, deposited perovskite films on plastic substrates. He then bent the substrate to put tensile (pulling apart) stress on the perovskite film while using a scanning electron microscope (SEM) to detect cracks. Once the film was cracked, the researchers then bent the substrate in the opposite direction to see if compressive stress might heal those cracks.

Sure enough, SEM imaging showed that the cracks had disappeared. To make sure the cracks were fully healed and not merely hidden, the researchers used a technique known as X-ray diffraction. By measuring the size of a material's atomic lattice, the technique can reveal whether a formerly cracked area is now able to carry a mechanical load -- a surefire sign that the crack is healed. Those tests also indicated fully healed cracks.

The researchers found that heat was just as effective in healing cracks. Temperatures around 100 degrees Celsius -- quite modest heating by material science standards -- were enough to completely heal cracks in perovskite films.

Padture says that the research was aimed at better understanding the basic properties of perovskite materials, and more work needs be done to develop methods of applying this information in a commercial setting. But knowing that perovskite films are easily healed could be useful as these kinds of solar cells move toward commercialization.

"It's good news," Padture said. "It suggests that fairly simple healing methods may help maintain performance in these kinds of solar cells."

BINGHAMTON, NY -- A team of mechanical engineers at Binghamton University, State University of New York investigating a revolutionary kind of micro-switch has found another application for its ongoing research.

After finding a new type of MEMS (microelectromechanical system) that allows better control, the researchers have used that knowledge to build an air-pressure sensor that could improve many everyday devices.

"This is the same mechanism as devices we've designed in the past, but it's a different application," said principal investigator Shahrzad "Sherry" Towfighian, an associate professor of mechanical engineering at Binghamton's Thomas J. Watson School of Engineering and Applied Science.

"The heart of the sensor still consists of four electrodes, and conventional sensors have two electrodes," said Towfighian. "That allows us to better tune the properties of the system."

The study was funded through a $480,958 grant from the National Science Foundation. Binghamton University PhD student Mark Pallay conducted much of the research under the supervision of Towfighian and her co-principal investigator, Distinguished Professor Ronald N. Miles of the Mechanical Engineering Department. Pallay has since graduated and started working at Seagate Technology as a research and development engineer.

One advantage of this MEMS -- a microscopic device with moving parts that is produced in the same way as electronics -- is its self-contained design. There's no need for a computer to analyze the readings, making the response time faster and more reliable.

"It not only senses the pressure but also triggers a switch," Towfighian said. "Usually a sensor needs to sense the pressure, process it through software to decide if the right conditions have been met and then trigger the switch. This one is a compact pressure sensor and switch, so by sending the voltage to one of the electrodes, you can make it work at different pressures."

As with all the MEMS switches that the Binghamton University team has designed so far, this new offering can have a multitude of uses, such as measuring barometric pressure, monitoring oxygen for premature babies at hospitals or detecting tire pressure in vehicles.

"Sometimes it's critical to detect the pressure threshold," Towfighian said. "For example, you're in an airplane and you want the air masks to come down if the air pressure drops below a certain amount. It's very easy to set the bias voltage to trigger automatically."

She added that the way the switch is built with four electrodes also means a longer lifespan: "Often there is a problem with the current devices that they have a limited lifespan because of having two electrodes, but having two other electrodes enables us to make it more durable and increase the life of the device."

The paper, "A Tunable Electrostatic MEMS Pressure Switch," was published in IEEE Transactions on Industrial Electronics.

Leesburg, VA, February 12, 2020--Mobile devices proved both reliable and accurate for the clinical decision to administer IV thrombolysis in patients with acute stroke, according to an ahead-of-print article in the April issue of the American Journal of Roentgenology (AJR).

To assess reliability and accuracy of IV thrombolysis recommendations made after interpretation of head CT images of patients with acute stroke symptoms displayed on smartphone or laptop reading systems--compared with those made after interpretation of images displayed on a medical workstation monitor--Antonio J. Salazar at the University of Los Andes in Bogotá, Columbia utilized a factorial design with 188 patients, four radiologists, and three reading systems to produce 2256 interpretations.

To evaluate reliability, Salazar and colleagues calculated the intraobserver and interobserver agreements using the intraclass correlation coefficient (ICC) and five interpretation variables: hemorrhagic lesions, intraaxial neoplasm, stroke dating (acute, subacute, chronic), hyperdense arteries, and infarct size assessment. Accuracy equivalence tests were also performed for the IV thrombolysis recommendation; for this variable, sensitivity, specificity, and ROC curves were evaluated.

Good or very good intraobserver agreements were observed for all the variables. Specifically, for those variables required to establish contraindications for IV thrombolysis, the agreements were ranked as very good. "This finding is important," wrote Salazar et al., "because it reflects the good performance of mobile devices to evaluate the most significant imaging variables for clinical decisions."

For IV thrombolysis recommendation, the main subject of this evaluation, the interobserver agreements for the three reading systems were ranked as very good (ICC > 0.88). Similarly, very good intraobserver agreements were observed for all comparisons (ICC > 0.84). The AUC values (0.83-0.84) and sensitivities (0.94-0.95) for IV thrombolysis recommendation were equivalent among all the reading systems at a 5% equivalent threshold.

A unique assessment of imaging-based recommendations for the administration of IV recombinant tissue plasminogen activator based on unenhanced brain CT scans, Salazar also noted: "These results constitute a strong foundation for the development of mobile-based telestroke services because they increase neuroradiologist availability and the possibility of using reperfusion therapies in resource-limited countries."

GAINESVILLE, Fla. --- Birds of a feather don't always flock together: Peer into a forest canopy, and you will likely spot multiple bird species flying and feeding together, a phenomenon most spectacular in the Amazon where 50 species may travel as a unit. But are birds in these mixed flocks cooperating with one another or competing?

A new study suggests both.

In an analysis of nearly 100 North Florida flocks, Florida Museum of Natural History researchers found similar bird species were significantly more likely to flock together than hunt alone, working as a group to stay safe from predators while cruising the canopy in search of insects. Species kept competition within the flock low, however, by differentiating their foraging technique, their choice of hunting spot or the general distance they kept from a tree trunk.

In other words, think of flock dynamics like a K-pop band, said study lead author Harrison Jones.

"You have to be similar enough to the other members to get along as a group but specialized in some way: There's the leader, the one who raps, the one who plays guitar," said Jones, a doctoral student in the University of Florida's department of biology. "It's the same with birds. They hang out together because they share things in common, but they can't share too much. If you're so similar that you're eating each other's lunch, then you have a serious problem."

North Florida's winter flocking community is "probably the most complex in North America," Jones said, featuring dozens of migratory species and a bevy of foraging opportunities. Still, the researchers were surprised to see how specialized the birds' foraging habits were - a feature more reminiscent of the Amazon than North America.

The study documented previously unknown foraging behaviors in Florida, including the yellow-throated warbler's habit of hanging sideways or upside down on palm fronds to feed on insects. Orange-crowned warblers probed the interior of dead leaves while pine warblers combed through air plants.

"These are very tropical features - not something I expected to see in a subtropical environment like Florida," said study co-author Scott Robinson, Florida Museum Ordway Eminent Scholar and Jones' adviser. Robinson has studied tropical bird species since 1977, with a focus on Central and South America. "Palm trees are not easy to feed from. It takes a very specialized bird using a specialized technique."

Species that pick insects off live leaves and nab them in the air - the most common foraging techniques - were relatively abundant in mixed flocks. These included ruby-crowned kinglets, blue-gray gnatcatchers and pine warblers. But birds that hunt exclusively in harder-to-find material tended to be represented by a single member per flock. These specialists called repeatedly, as though to warn others of their kind "Hands off! This is my flock," Jones said.

The diversity of Florida's flocks ranged from three to 12 species and four to 36 individuals per flock. The researchers identified 14 species as regular participants in mixed flocks, with 10 species appearing in more than 80% of mixed flocks.

"We didn't know birds were spending 80-90% of their time in these flocks," Jones said. "It's clear that this behavior is really important to their ecology and may explain why there's so much partitioning of resources within the flock. They're spending almost all their waking hours together."

One-flock shopping

Mixed-species flocks only occur during winter, birds' non-breeding season. Finding enough food in colder months is vital for birds, which must strike the right balance between putting on sufficient body fat to survive the night while staying lean enough to make a quick escape from a predator, Jones said.

Hunting insects as a group can be a life-saver. Flock members rely on sentinel species, which also direct the flock's movements and pace, to sound the alarm if an owl or hawk swoops in. This allows the majority of birds in the flock to devote more attention to finding food. Traveling in numbers also lessens a bird's chance of being the unlucky victim if a predator attacks.

In North Florida's mixed-species flocks, tufted titmice and Carolina chickadees play the role of sentinels - "blabbermouth birds," Jones said.

"They're always giving little contact calls to one another as an 'all clear,'" he said. "If they stop, everybody else is on edge. When they see a predator, they give an alarm call, and everybody in the flock will freeze."

But these sentinel species don't appear to be actively recruiting flock members, Jones said: "They're just going about their business, and everyone else joins them."

As with any good K-pop band, group choreography is key. Jones and his co-author and birding partner Mitchell Walters, also a UF doctoral student in biology, noticed mixed flocks were dominated by small, swift birds. Larger insect-eating birds, such as woodpeckers, often couldn't keep up, joining temporarily but dropping behind when the flock moved on.

Birds that foraged in the understory, such as thrushes, didn't flock at all.

To piece together the story of Florida's mixed flocks, Jones and Walters, both seasoned birders, spent many hours in Gainesville's upland hammocks, developing cricks in their necks as they stared into the canopy through their binoculars.

"By the end of the study, we started to recognize how each of these species has its own way of moving and foraging, its own personality - something birders often talk about," Jones said. "In many ways, this study was inspired by talking to local birdwatchers and just going birding. They'll say things like 'Of course you only get one vireo per flock.' And the science agreed."

Warfighters on the battlefield often rely on machines, vehicles and other technologies with rotating parts to complete their mission. Army researchers have devised a new method of testing for a major factor in equipment failure and breakdown in order to ensure that those tools meet the proper standard of quality.

When mechanical parts slide against each other for long periods of time, the constant grinding may wear down the metal surfaces until the parts are no longer functional. The study of friction, wear and lubrication as two or more surfaces interact in relative motion is known as tribology, and its importance in material science and engineering has led researchers to find new ways to examine dry mechanical contact.

Researchers at the U.S. Army Combat Capabilities Development Command's Army Research Laboratory recently developed a new approach to analyze the tribological response between steel and silicon nitride that takes place as the two metals interact, rather than after the samples have cooled off.

This latest method of studying wear and tear may allow researchers to observe fleeting chemical reactions that occur at the contact site.

"The mechanical system is very dynamic during operation," said Dr. Stephen Berkebile, Army research physicist. "If it is not captured during operation and, instead, measured when not moving quickly, the transient chemical reactions and physical changes would not be captured since the system may change after cooling down from the frictional heating."

Berkebile acted as one of the Army researchers working together with the University of North Texas to study the sliding interaction between steel and silicon nitride. More specifically, the team was trying to investigate why increasing the sliding speed between steel and silicon nitride decreased their rate of friction and wear as they made contact.

According to the researchers, the interaction between steel and silicon nitride is one that commonly takes place during the dry machining process of certain cutting tools and in emergency situations with high speed bearings when they lose their lubrication source, like those in jet engine turbines. Understanding the kinetics behind the high-speed sliding contact between these two metals would be vital in developing better and safer vehicles and equipment for Soldiers.

"Hybrid bearings with the steel/silicon nitride contact are increasingly being used in turbomachinery within helicopter propulsion systems," Berkebile said. "Such hybrid bearings are finding more and more use in rotorcraft and helicopter propulsion systems where they are operated at high speeds."

The researchers conducted the experiment using a Ball on Disk tribometer that slid a rolling silicon nitride ball against a steel rotating disk that was heated to 120 degrees Celsius with a hot plate underneath.

A stereo-optical microscope with a color Charge-Coupled Device, or CCD, camera and an infrared camera obtained thermal imaging data as the rotating speed of the disk sped up from 1 m/s to 16 m/s. Afterwards, the researchers conducted an analysis of the wear tracks using a backscatter electron detector that mapped the elemental composition of the leftover film residue.

"By combining two optical methods with real-time friction data, we could understand the chemical transition in the wear mechanism," Berkebile said. "We were able to correlate the friction, temperature and chemical state of the mechanical contact during active operation of the experiment as the chemical reaction was occurring."

According to the researchers, this experiment represented the first known attempt to analyze the tribological response of steel and silicon nitride in the middle of a high sliding speed test.

Furthermore, the data resulting from this bold venture provided new information about the nature of tribological effects that took place.

The team discovered that the frictional heating caused at a threshold sliding speed of around 4.5 m/s induced a chemical reaction that left behind a lubricating thin film at the highly loaded contact zone.

This slippery thin film was what allowed the mechanical interaction between steel and silicon nitride to demonstrate lower friction and wear as the sliding speed increased. Using the new approach, the team managed to pinpoint the exact time that the chemical reaction occurred from observations of the wear tracks' color change during the experiment.

Additionally, the researchers determined that this phenomenon is fully active when the sliding speed rose above 9 m/s under gear- and bearing-like conditions.

Based on the analysis of the wear tracks, the researchers verified that a series of oxidation reactions must have taken place as a result of the interplay between iron, oxygen and silicon under high temperatures from frictional heating.

"We found that a smooth transition between one chemical reaction to another occurs during the transition between the low friction and wear state and the high friction and wear state," Berkebile said. "The chemical reaction also requires frictional heating to be maintained, and thus can 'extinguish' itself after a few seconds if the low friction state is achieved and the frictional heating is reduced at intermediate speeds."

According to Berkebile, this new in-situ approach to examining dry sliding mechanical contacts holds the potential to significantly improve the Army's efforts to develop machinery that can better withstand high temperatures, loads and speeds.

"Army helicopters have a requirement to operate for 30 minutes after lubrication has been lost from the drive system," Berkebile said. "From this study, we have learned that for drive systems that contain hybrid components, such as silicon nitride/steel bearings, the materials may actually last longer if they are sliding at a higher rather than lower speed, which is really counterintuitive."

Transmission of diseases from wildlife to livestock is a common threat in Alberta, according to new research by University of Alberta biologists. Foothills in the southwestern part of the province are home to wild elk as well as cattle on ranchlands--and when the species intermingle, the potential for disease to spread grows.

"One of the biggest risks to the livestock industry is the transmission of disease from wildlife to livestock," said Mark Boyce, professor in the Department of Biological Sciences. "There is a long list of diseases that occur between livestock and wildlife, including anthrax, bovine tuberculosis, brucellosis, and many species of worms. And in addition to infecting one another, many of the diseases that are shared by wildlife and livestock are zoonotic, meaning that they also can infect humans."

The researchers used data gathered from combined with cattle management information from 16 cattle operations in southern Alberta to identify locations and times where the probability of disease transmission is high. For example, the highest risk occurs in winter months, when livestock and elk are in the same pastures and accessing the same resources.

Based on these data, the researchers have developed guidelines to help producers minimize the risk of infection.

"Livestock management that minimizes the risk of contact with wildlife will reduce the risk of disease transmission," said Boyce. "This includes keeping cattle in pastures near farm buildings during winter and calving season. It is also important to keep mineral supplements and hay next to ranch buildings, again to reduce the contact between cattle and elk.

The Global Precipitation Measurement mission or GPM satellite provided a look at the rainfall occurring within Tropical Cyclone Uesi and found heaviest rainfall in the southern quadrant of the storm.

Uesi is in the South Pacific Ocean and has been affecting New Caledonia. New Caledonia is a collectivity of France, located south of Vanuatu and about 1,210 km (750 miles) east of Australia.

The GPM's core satellite passed over Uesi on Feb. 12 at 12:11 p.m. EST (1711 UTC). GPM found heaviest rainfall southwest of the center, falling at a rate of 1.6 inches (40 mm) per hour. Directly south of the center were areas where rainfall rates were falling at a rate of 1 inch (25 mm) per hour. Scattered light rain, falling at less than 0.2 inches (less than 5 millimeters) per hour appeared to be occurring in the rest of the storm.

On Feb 12 at 1 a.m. EST (5 p.m. New Caledonia local time), Meteo-France, which forecasts for New Caledonia, noted that Uesi's maximum sustained winds were near 110 kph (68 mph/59 knots). Uesi was moving to the southwest. It was centered near latitude 23.5 degrees south and longitude 162.8 degrees east, about 450 km (280 miles) west-southwest of Noumea.

Meteo-France noted, "The rains eased in the afternoon, except over the Canala region where the showers are still continuing this evening. In the past 12 hours, we have noted 80 to 130 mm (3.1 to 5.1 inches) in the relief of the South and 80 mm (3.1 inches) in 3 hours in the town of Canala. The wind remains strong with gusts up to 90 kph (60 mph/49 knots) on the chain, on the West Coast and the South. Uesi is moving away from the Caledonian coasts, its influence is still felt throughout the country. Conditions remain disturbed overnight, with a gradual improvement in the north."

Uesi is expected to turn to the southwest and become subtropical after a day or two, off the coast of eastern Australia.

Tropical cyclones/hurricanes are the most powerful weather events on Earth. NASA's expertise in space and scientific exploration contributes to essential services provided to the American people by other federal agencies, such as hurricane weather forecasting.

What if the key to a better understanding of schizophrenia has been here all along--but researchers haven't had the resources to study it?

Now, thanks to the pooled data and insights from researchers around the world, USC researchers have the clearest picture yet of brain abnormalities associated with the serious mental illness that impacts 20 million people worldwide.

A new study, published February 12 in the American Journal of Psychiatry, analyzed MRI scans of individuals with 22q11.2 deletion syndrome, also referred to as "22q" or DiGeorge syndrome, a genetic disorder caused by a small segment of missing DNA on chromosome 22. This tiny missing portion of chromosome 22 can affect every system in the body and is the strongest known genetic risk factor for schizophrenia.

Compared to a control group, those with 22q had overall significantly lower brain volumes, as well as lower volumes in specific structures including the thalamus, hippocampus and amygdala, compared with the control group. They also had higher volumes in several brain structures. The magnitude of these abnormalities, especially in those 22q individuals with psychosis, was larger than is typical in many other common psychiatric conditions.

About a quarter of people with 22q develop schizophrenia or experience psychotic symptoms, so studying the syndrome provides a unique window into how such psychiatric problems develop over time. But the disorder is rare--about one in 4,000 people have it, making it tough for researchers at any single institution to study the syndrome.

To address that problem, the Enhancing Neuro Imaging Genetics through Meta-Analysis (ENIGMA) consortium launched a new working group to study 22q using data collected by researchers across the U.S., Canada, Europe, Australia and South America. ENIGMA is led by Paul Thompson, associate director of the Mark and Mary Stevens Neuroimaging and Informatics Institute (INI) at the Keck School of Medicine of USC, who has been uniting researchers around the world to pool data and insights on rare diseases for a decade.

"We've pieced together many of the major research centers studying 22q11DS around the world to create the largest-ever neuroimaging study of the disorder," said Christopher Ching, a postdoctoral researcher at the INI and first author of the study.

To get a clear picture of the brain abnormalities associated with schizophrenia in individuals with 22q, the study's authors examined magnetic resonance imaging (MRI) scans from 533 people with the disorder and 330 healthy control subjects. Using advanced analytic techniques developed at the INI, the authors measured and mapped structural differences between the brains of the two groups.

Notably, the brain changes seen in people with 22q and psychosis significantly overlapped with the brain changes observed in previous neuroimaging studies of schizophrenia and other serious mental illnesses including bipolar disorder, major depression and obsessive-compulsive disorder.

"That's important because these overlapping brain signatures add evidence to support 22q11DS as a good model for understanding schizophrenia in the wider population," Ching said. "And thanks to these large ENIGMA studies, we now have a way to directly compare standardized brain markers across major psychiatric illnesses on an unprecedented scale."

All the elements are there to begin with, so to speak; it's just a matter of figuring out what they are capable of - alone or together. For Leslie Schoop's lab, one recent such investigation has uncovered a layered compound with a trio of properties not previously known to exist in one material.

With an international interdisciplinary team, Schoop, assistant professor of chemistry, and Postdoctoral Research Associate Shiming Lei, published a paper last week in Science Advances reporting that the van der Waals material gadolinium tritelluride (GdTe3) displays the highest electronic mobility among all known layered magnetic materials. In addition, it has magnetic order, and can easily be exfoliated.

Combined, these properties make it a promising candidate for new areas like magnetic twistronic devices and spintronics, as well as advances in data storage and device design.

The Schoop team initially uncovered these unique characteristics in early 2018 shortly after beginning the project. Their first success was in demonstrating that GdTe3 is easily exfoliable down to ultrathin flakes below 10nm. Subsequently, the team spent two years refining the purity of the material crystals to a state that only served to amplify the results. The lab has already shipped a number of samples to researchers eager to explore how the compound fits into a category previously occupied only by black phosphorous and graphite. High mobility is rare in layered materials.

The properties detailed in the study, described as quantum oscillations or "wiggles" that can be measured, are so pronounced that they were observed without the special probes and equipment generally found in national laboratories.

"Usually, if you see these oscillations, it depends partly on the quality of your sample. We really sat down and made the best crystals possible. Over the course of two years we improved the quality, so that these oscillations became more and more dramatic," said Schoop. "But the first samples already showed them, even though with the first crystals we grew we didn't know exactly what we were doing," Schoop said.

"It was very exciting for us. We saw these results of highly mobile electrons in this material that we didn't expect. Of course we were hoping for good results. But I didn't anticipate it to be as dramatic," Schoop added.

Lei characterized the news as a "breakthrough" largely because of the high mobility. "Adding this material into the zoo of 2D van der Waals materials is like adding a newly discovered ingredient for cooking, which allows for new flavors and dishes," he said.

"So first, you get these materials out. The next thing is identifying the potential: what is the function of the device you can make from it? What is the performance we can further improve as a next generation of materials along this line?"

A rare-earth tritelluride, GdTe3 has a carrier mobility beyond 60,000 cm2V-1s-1. This means that if a field of one volt per cm is applied to the material, the electrons move with a net speed of 60,000 cm per second. To compare, mobilities in other magnetic materials are often found to be only a few hundred cm2V-1s-1 .

"High mobility is important because this means that electrons inside the materials are able to travel at high speeds with minimal scattering, thus reducing the heat dissipation of any electronic devices built from it," said Lei.

Van der Waals materials - in which the layers are bound by a weak force - are the parent compounds of 2D materials. Researchers are studying them for next-generation device fabrication and also for use in twistronics, first described in the science community only a few years ago. With twistronics, the layers of 2D materials are misaligned or twisted as they lay atop one another. The judicious misalignment of the crystal lattice can change electrical, optical and mechanical properties in ways that may yield new opportunities for applications.

In addition, it was discovered some 15 years ago that van der Waals materials could be exfoliated down to the thinnest layer by using something as commonplace as scotch tape. This revelation excited many new developments in physics. Finally, 2D materials were only recently revealed to exhibit magnetic order, in which the spins of electrons are aligned to each other. All "thin" devices -- hard drives, for example - are based on materials ordering magnetically in different ways that produce different efficiencies.

"We have found this material where the electrons shoot through as on a highway - perfect, very easily, fast," said Schoop. "Having this magnetic order in addition and the potential to go to two dimensions is just something that was uniquely new for this material."

The results of the study are a strong showing for Schoop's young lab, established just over two years ago. They are the product of a collaboration with the Princeton Center for Complex Materials, an NSF-funded Materials Research Science and Engineering Center, and co-authors Nai Phuan Ong, Sanfeng Wu, and Ali Yazdani, all faculty with Princeton's Department of Physics.

To fully understand the electronic and magnetic properties of GdTe3, the team also collaborated with Boston College for exfoliation tests, and Argonne National Laboratory and the Max Planck Institute for Solid State Research to understand the electronic structure of the material using synchroton radiation.

From a broader perspective, what satisfied Schoop most about the study was the "chemical intuition" that led the team to begin the investigation with GdTe3 in the first place. They suspected there would be promising results. But the fact that GdTe3 yielded them so quickly and emphatically is a sign, said Schoop, that chemistry has significant contributions to make to the field of solid state physics.

"We're a group in the chemistry department and we figured out that this material should be of interest for highly mobile electrons based on chemical principles," said Schoop. "We were thinking about how the atoms were arranged in these crystals and how they should be bonded to each other, and not based on physical means, which is often understanding the energy of electrons based on Hamiltonians.

"But we took a very different approach, much more related to drawing pictures, like chemists do, related to orbitals and things like that," she said. "And we were successful with this approach. It's just such a unique and different approach in thinking about exciting materials."