Tech

Striga hermonthica, also known as purple witchweed, is an invasive parasitic plant that threatens food production in sub-Saharan Africa. It is estimated to ruin up to 40 per cent of the region's staple crops, the equivalent of $7-10 billion, putting the livelihoods and food supplies of 300 million people in danger.

Striga has an Achilles' heel: it's a parasite that attaches to the roots of other plants. If it can't find a host plant to attach to, it dies. Scientists have found a way to exploit Striga's Achilles' heel to eradicate it from farmers' fields.

Salim Al-Babili, associate professor of plant science at the King Abdullah University of Science and Technology, and colleagues found that they could trick Striga seeds that a host plant was growing nearby. When conditions are right, the Striga seeds germinate, but without a host plant to attach to, they cannot survive.

The scientists take advantage of plant hormones called strigolactones, which are exuded by plant roots. It is these hormones that trigger Striga seeds to germinate. By treating bare crop fields in Burkina Faso with artificial strigolactones, the scientists found that they were able to reduce the number of Striga plants by more than half.

The scientists' solution can be applied to crop fields over the course of a crop rotation, and doesn't require additional water - the treatment begins to work when the rains fall. This has obvious advantages in a region where water is scarce. Al-Babili has been awarded a $5 million grant by the Bill & Melinda Gates Foundation to continue developing real-world solutions to the Striga problem.

This new method will allow farmers and scientists to work together to combat the spread of the invasive Striga plant and help protect the food security of 300 million people in sub-Saharan Africa. The work will be published in Plants, People, Planet.

Physicists from MIT and elsewhere have performed the first run of a new experiment to detect axions -- hypothetical particles that are predicted to be among the lightest particles in the universe. If they exist, axions would be virtually invisible, yet inescapable; they could make up nearly 85 percent of the mass of the universe, in the form of dark matter.

Axions are particularly unusual in that they are expected to modify the rules of electricity and magnetism at a minute level. In a paper published today in Physical Review Letters, the MIT-led team reports that in the first month of observations the experiment detected no sign of axions within the mass range of 0.31 to 8.3 nanoelectronvolts. This means that axions within this mass range, which is equivalent to about one-quintillionth the mass of a proton, either don't exist or they have an even smaller effect on electricity and magnetism than previously thought.

"This is the first time anyone has directly looked at this axion space," says Lindley Winslow, principal investigator of the experiment and the Jerrold R. Zacharias Career Development Assistant Professor of Physics at MIT. "We're excited that we can now say, 'We have a way to look here, and we know how to do better!'"

Winslow's MIT co-authors include lead author Jonathan Ouellet, Chiara Salemi, Zachary Bogorad, Janet Conrad, Joseph Formaggio, Joseph Minervini, Alexey Radovinsky, Jesse Thaler, and Daniel Winklehner, along with researchers from eight other institutions.

Magnetars and munchkins

While they are thought to be everywhere, axions are predicted to be virtually ghost-like, having only tiny interactions with anything else in the universe.

"As dark matter, they shouldn't affect your everyday life," Winslow says. "But they're thought to affect things on a cosmological level, like the expansion of the universe and the formation of galaxies we see in the night sky."

Because of their interaction with electromagnetism, axions are theorized to have a surprising behavior around magnetars -- a type of neutron star that churns up a hugely powerful magnetic field. If axions are present, they can exploit the magnetar's magnetic field to convert themselves into radio waves, which can be detected with dedicated telescopes on Earth.

In 2016, a trio of MIT theorists drew up a thought experiment for detecting axions, inspired by the magnetar. The experiment was dubbed ABRACADABRA, for the A Broadband/Resonant Approach to Cosmic Axion Detection with an Amplifying B-field Ring Apparatus, and was conceived by Thaler, who is an associate professor of physics and a researcher in the Laboratory for Nuclear Science and the Center for Theoretical Physics, along with Benjamin Safdi, then an MIT Pappalardo Fellow, and former graduate student Yonatan Kahn.

The team proposed a design for a small, donut-shaped magnet kept in a refrigerator at temperatures just above absolute zero. Without axions, there should be no magnetic field in the center of the donut, or, as Winslow puts it, "where the munchkin should be." However, if axions exist, a detector should "see" a magnetic field in the middle of the donut

After the group published their theoretical design, Winslow, an experimentalist, set about finding ways to actually build the experiment.

"We wanted to look for a signal of an axion where, if we see it, it's really the axion," Winslow says. "That's what was elegant about this experiment. Technically, if you saw this magnetic field, it could only be the axion, because of the particular geometry they thought of."

In the sweet spot

It is a challenging experiment because the expected signal is less than 20 atto-Tesla. For reference, the Earth's magnetic field is 30 micro-Tesla and human brain waves are 1 pico-Tesla. In building the experiment, Winslow and her colleagues had to contend with two main design challenges, the first of which involved the refrigerator used to keep the entire experiment at ultracold temperatures. The refrigerator included a system of mechanical pumps whose activity could generate very slight vibrations that Winslow worried could mask an axion signal.

The second challenge had to do with noise in the environment, such as from nearby radio stations, electronics throughout the building turning on and off, and even LED lights on the computers and electronics, all of which could generate competing magnetic fields.

The team solved the first problem by hanging the entire contraption, using a thread as thin as dental floss. The second problem was solved by a combination of cold superconducting shielding and warm shielding around the outside of the experiment.

"We could then finally take data, and there was a sweet region in which we were above the vibrations of the fridge, and below the environmental noise probably coming from our neighbors, in which we could do the experiment."

The researchers first ran a series of tests to confirm the experiment was working and exhibiting magnetic fields accurately. The most important test was the injection of a magnetic field to simulate a fake axion, and to see that the experiment's detector produced the expected signal -- indicating that if a real axion interacted with the experiment, it would be detected. At this point the experiment was ready to go.

"If you take the data and run it through an audio program, you can hear the sounds that the fridge makes," Winslow says. "We also see other noise going on and off, from someone next door doing something, and then that noise goes away. And when we look at this sweet spot, it holds together, we understand how the detector works, and it becomes quiet enough to hear the axions."

Seeing the swarm

In 2018, the team carried out ABRACADABRA's first run, continuously sampling between July and August. After analyzing the data from this period, they found no evidence of axions within the mass range of 0.31 to 8.3 nanoelectronvolts that change electricity and magnetism by more than one part in 10 billion.

The experiment is designed to detect axions of even smaller masses, down to about 1 femtoelectronvolts, as well as axions as large as 1 microelectronvolts.

The team will continue running the current experiment, which is about the size of a basketball, to look for even smaller and weaker axions. Meanwhile, Winslow is in the process of figuring out how to scale the experiment up, to the size of a compact car -- dimensions that could enable detection of even weaker axions.

"There is a real possibility of a big discovery in the next stages of the experiment," Winslow says. "What motivates us is the possibility of seeing something which would change the field. It's high-risk, high-reward physics."

The results of a study led by a team from the Barcelona Institute for Global Health (ISGlobal), a centre supported by "la Caixa", suggest that the risk of a child developing symptoms of attention deficit hyperactivity disorder (ADHD) may be modulated by the mother's diet during pregnancy. The study, published in the Journal of Pediatrics, analysed samples of umbilical cord plasma to quantify the levels of omega-6 and omega-3 that reach the foetus. The statistical analysis showed a higher omega-6:omega-3 ratio to be associated with a higher risk of ADHD symptoms at seven years of age.

Omega-6 and omega-3 are long-chain polyunsaturated fatty acids that play a crucial role in the function and architecture of the central nervous system, particularly during the later stages of gestation. These two fatty acids compete for incorporation into cell membranes and are primarily obtained through diet. Since omega-6 and omega-3 have opposing physiological functions--the former promotes systemic pro-inflammatory states, while the latter promotes anti-inflammatory states--a balanced intake of these two fatty acids is important. Previous research had shown that children with ADHD symptoms have a higher omega-6:omega-3 ratio.

The authors studied data from 600 children living in four Spanish regions (Asturias, Basque Country, Catalonia and Valencia) who are participating in the INMA Project. They analysed umbilical cord plasma samples and data from questionnaires completed by the children's mothers. ADHD symptoms were assessed using two standard questionnaires: the first completed by the children's teachers at age four years, and the second by their parents at age seven years.

The results showed that, at age seven years, the number of ADHD symptoms increased by 13% per each unit increase in the omega-6:omega-3 ratio in umbilical cord plasma. The study analysed the number of symptoms in the children who met the diagnostic criteria for ADHD (minimum six symptoms) and also in the children with a smaller number of ADHD symptoms. The ratio of the two fatty acids was associated with the number of ADHD symptoms present but not with diagnosis of the disorder, and only in the assessment carried out at seven years of age. The authors suggest that the assessment carried out at four years of age may have been affected by a measurement error because ADHD symptoms reported at early ages may be caused by a neurodevelopmental delay falling within the normal range.

"Our findings are in line with previous studies that established a relationship between the omega-6:omega-3 ratio in mothers and various early neurodevelopmental outcomes," commented Mónica López-Vicente, ISGlobal researcher and lead author of the study.

"Although the association was not clinically significant, our findings are important at the level of the population as a whole," noted López-Vicente. "If a large proportion of the population is exposed to a high omega-6:omega-3 ratio, the distribution for ADHD symptom scores would likely move to the right and the prevalence of extreme values would increase, leading to a negative impact on the community's health costs and productivity."

"This study adds more evidence to the growing body of research on the importance of maternal diet during pregnancy," commented ISGlobal researcher Jordi Júlvez, a co-author of the study. "The nutrient supply during the earliest stages of life is essential in that it programs the structure and function of the organs, and this programming, in turn, has an impact on health at every stage of life. As the brain takes a long time to develop, it is particularly vulnerable to misprogramming. Alterations of this sort could therefore lead to neurodevelopmental disorders."

COLUMBUS, Ohio--Maybe running comes easy, each stride pleasant and light. Maybe it comes hard, each step a slog to the finish. Either way, the human body is constantly calibrating, making microscopic adjustments to keep us from falling as we weekend-warrior our way to greatness.

Runners constantly--and unconsciously--make minor corrections to their running form to keep their bodies upright, a recent study has found.

"You might think running is just a repetition of identical steps, and it might look like that to the naked eye," said Nidhi Seethapathi, lead author of the study. "But actually, there are really small errors that happen when you run, and you have to constantly correct to avoid falling down. Our muscles and our senses are not perfect, and that leads to errors. If we didn't correct for these self-generated errors, we would fall. Our study investigates how people correct such errors."

The study was part of Seethapathi's doctoral thesis in mechanical and aerospace engineering at The Ohio State University and was published earlier this month in the journal eLife. She has since accepted a postdoctoral position at The University of Pennsylvania.

"The tasks that your body does almost subconsciously have all these tiny movements behind them," said Manoj Srinivasan, a co-author of the study and associate professor of mechanical and aerospace engineering at Ohio State. "Those little movements were what we were looking to understand."

To understand how humans run without falling, the research team put volunteers on a treadmill and had them run at three different constant speeds. The team monitored and measured motion in each runner's torso, the placement of each footstep and the force with which the leg pushes against the ground. The volunteers were average runners--not couch potatoes, but not marathoners, either.

They found that those runners automatically corrected for minor deviations in the movement of their torsos--their center of mass--by making slight changes to the place each footstep landed and by making miniscule adjustments to the amount of force with which their leg hit the ground. Seethapathi and Srinivasan found that they could predict how runners would change their footsteps or force by noting changes in the location of their torsos.

They also found that runners, by and large, corrected imperfections in a step by their very next step, indicating that the human body has the ability to "fix" its running gait in order to stay upright. And their research showed that imperfections in a running stride that would have caused a runner to fall to the side were corrected more quickly than errors that would have caused a runner to topple forward or backward.

None of the errors examined in this study included external factors--a crack in pavement, for example, or a tree root on a trail. But what they did show was the human body's great capacity for keeping itself upright while moving--something that robots, in general, struggle to do.

"We try to work at the intersection of robotics and human movement," Seethapathi said, "in that we use metrics that are traditionally used in robotics on human movement and then take inspiration from humans to inform robotic movement."

The study's findings could be used to engineer robots that are able to walk or run without toppling over, or to build an exoskeleton that moves more intuitively with the human body, Srinivasan said.

"In terms of movement, humans are just vastly superior to current robots," Srinivasan said. "Our research is sort of reverse engineering the human body to understand how humans and animals control their bodies to do these amazing tasks. While walking and running maybe don't sound amazing to people--because it is something most humans do almost every day--there have been a lot of technical challenges to making a robot that can walk or run without falling over, or to building an exoskeleton, for example, that can help a human regain movement while recovering from a stroke."

An exoskeleton is exactly what it sounds like: A mechanical skeleton, or parts of a skeleton, that people wear to help the human body do everything from lift heavy objects to regain movement after an injury or stroke.

This study builds on previous research in Srinivasan's lab that examined the ways humans walk.

They are the scavengers of the deep and the dead.

Hagfish are slimy bottom-dwellers that live off the carcasses of dead sea creatures and thrive in deep waters where oxygen is hard to come by. In fact, their hearts can keep on beating for 36 hours without any oxygen, making hagfish a champion among anoxia-tolerant fish.

A human heart, by contrast, becomes permanently damaged after just a few minutes without oxygen.

Now, University of Guelph research has uncovered clues as to how hagfish keep their hearts pumping even when they've run out oxygen. By unravelling the mysteries of the hagfish heart, this work could provide new ideas on how to protect the human heart when oxygen delivery is impaired, such as during a heart attack.

"We want to understand how these fish hearts can work for so long without oxygen because this could lead to innovative strategies for preserving human cardiac tissue during myocardial infarction or heart transplant," said Prof. Todd Gillis, who led this study along with recent MSc graduate Lauren Gatrell.

Gillis is a professor in the Department of Integrative Biology, and a founding member of U of G's Centre for Cardiovascular Investigations.

Gatrell and Gillis sought to understand what fuels hagfish hearts when they've run out of oxygen.

"We wanted to know which metabolic fuels were being used and how they were using them, given that the hearts of most vertebrates run out of cellular energy when oxygen is removed. This is what leads to the tissue damage."

Published in the Journal of Comparative Physiology, the study tested two potential fuel sources: glucose and glycerol.

Previously, Gillis found that during the beginning of an anoxia exposure, hagfish hearts use glycogen for energy, a form of stored glucose in muscles. But these glycogen stores aren't enough to keep the heart pumping during continuous anoxia exposure, and it was unclear what fuel took over once glycogen was depleted.

Gatrell exposed isolated hagfish hearts to 12 hours of anoxia or normoxia during which time she supplied the hearts with saline containing either glucose, glycerol or no fuel source, while measuring heart contraction.

During these experiments, the hearts continued to pump, even without oxygen.

"If you treated a mammalian heart in a similar manner, it would quickly stop beating and become permanently damaged. You'd also have to keep stimulating it with a mild electrical shock just to keep it beating. But the hagfish heart continues to generate enough electrical potential to keep working," Gillis said."They're kind of like zombie hearts; they literally will just keep beating. It's pretty amazing to see."

The experiments revealed that providing the hearts with glycerol during anoxia clearly enhanced the hearts' contraction -- even more so than when the hearts were supplied with glucose, which is typically the fuel that muscles prefer.

"We're still trying to figure out what this means," said Gillis. "These results raise so many more exciting questions. Is there a benefit to using glycerol? Is it some ancestral anomaly or the result of evolution that they are stimulated by glycerol?"

Gillis suspects that glycerol is being delivered to the heart from the liver.

"We think it's circulating through the fish in their blood," he said. "We found very high levels of glycerol in the liver, which is where it would be produced and then transported to the tissues."

He said he's fascinated that hagfish hearts react so strongly to glycerol and admitted he found it a bit weird.

"But just about everything about hagfish is bizarre. This is just another weird thing that they can do. Now we need to know how and why they do it."

Biophysicists have used an automated method to model a living system -- the dynamics of a worm perceiving and escaping pain. The Proceedings of the National Academy of Sciences (PNAS) published the results, which worked with data from experiments on the C. elegans roundworm.

"Our method is one of the first to use machine-learning tools on experimental data to derive simple, interpretable equations of motion for a living system," says Ilya Nemenman, senior author of the paper and a professor of physics and biology at Emory University. "We now have proof of principle that it can be done. The next step is to see if we can apply our method to a more complicated system."

The model makes accurate predictions about the dynamics of the worm behavior, and these predictions are biologically interpretable and have been experimentally verified.

Collaborators on the paper include first author Bryan Daniels, a theorist from Arizona State University, and co-author William Ryu, an experimentalist from the University of Toronto.

The researchers used an algorithm, developed in 2015 by Daniels and Nemenman, that teaches a computer how to efficiently search for the laws that underlie natural dynamical systems, including complex biological ones. They dubbed the algorithm "Sir Isaac," after one of the most famous scientists of all time -- Sir Isaac Newton. Their long-term goal is to develop the algorithm into a "robot scientist," to automate and speed up the scientific method of forming quantitative hypotheses, then testing them by looking at data and experiments.

While Newton's Three Laws of Motion can be used to predict dynamics for mechanical systems, the biophysicists want to develop similar predictive dynamical approaches that can be applied to living systems.

For the PNAS paper, they focused on the decision-making involved when C. elegans responds to a sensory stimulus. The data on C. elegans had been previously gathered by the Ryu lab, which develops methods to measure and analyze behavioral responses of the roundworm at the holistic level, from basic motor gestures to long-term behavioral programs.

C. elegans is a well-established laboratory animal model system. Most C. elegans have only 302 neurons, few muscles and a limited repertoire of motion. A sequence of experiments involved interrupting the forward movement of individual C. elegans with a laser strike to the head. When the laser strikes a worm, it withdraws, briefly accelerating backwards and eventually returning to forward motion, usually in a different direction. Individual worms respond differently. Some, for instance, immediately reverse direction upon laser stimulus, while others pause briefly before responding. Another variable in the experiments is the intensity of the laser: Worms respond faster to hotter and more rapidly rising temperatures.

The researchers fed the Sir Isaac platform the motion data from the first few seconds of the experiments -- before and shortly after the laser strikes a worm and it initially reacts. From this limited data, the algorithm was able to capture the average responses that matched the experimental results and also to predict the motion of the worm well beyond these initial few seconds, generalizing from the limited knowledge. The prediction left only 10 percent of the variability in the worm motion that can be attributed to the laser stimulus unexplained. This was twice as good as the best prior models, which were not aided by automated inference.

"Predicting a worm's decision about when and how to move in response to a stimulus is a lot more complicated than just calculating how a ball will move when you kick it," Nemenman says. "Our algorithm had to account for the complexities of sensory processing in the worms, the neural activity in response to the stimuli, followed by the activation of muscles and the forces that the activated muscles generate. It summed all this up into a simple and elegant mathematical description."

The model derived by Sir Isaac was well-matched to the biology of C. elegans, providing interpretable results for both the sensory processing and the motor response, hinting at the potential of artificial intelligence to aid in discovery of accurate and interpretable models of more complex systems.

"It's a big step from making predictions about the behavior of a worm to that of a human," Nemenman says, "but we hope that the worm can serve as a kind of sandbox for testing out methods of automated inference, such that Sir Isaac might one day directly benefit human health. Much of science is about guessing the laws that govern natural systems and then verifying those guesses through experiments. If we can figure out how to use modern machine learning tools to help with the guessing, that could greatly speed up research breakthroughs."

Thousands of military service members lost their lives or were severely injured while serving our country during America's longest war, known as the Global War on Terrorism. A researcher at The University of Texas at San Antonio (UTSA) is now documenting the war's casualty statistics, mortality trends and treatment advances.

UTSA researcher, Jeffrey Howard, published an article today in JAMA Surgery that takes a closer look at the casualties of war and the trauma care they received during the military conflicts in Afghanistan and Iraq that began after September 11, 2001.

Howard, the paper's lead author and an assistant professor in the Department of Kinesiology, Health and Nutrition in the UTSA College of Education and Human Development (COEHD), and his collaborators analyzed data compiled from Department of Defense (DoD) databases about the 56,763 injuries recorded in Afghanistan and Iraq from October 1, 2001 through December 31, 2017.

The researchers assessed casualty status (alive, killed in action (KIA) or died of wounds (DOW), the case-fatality rate (CFR) and the contribution of different interventions (use of tourniquets, blood transfusions, and transport to surgical facility within 60 minutes) to changes in the CFR.

"The Afghanistan and Iraq conflicts have the lowest case-fatality rates in U.S. history, but the
purpose of this study was to provide the most comprehensive assessment of the trauma system by compiling the most complete data on the conflicts and analyzing multiple interventions and policy changes simultaneously," explained Howard. "We used novel analytical methods to simulate what mortality would have been without key interventions."

Key findings suggest that injury patterns and the severity of sustained injuries increased during the war. For example:

Injuries caused by explosives increased 26 percent in Afghanistan and 14 percent in Iraq

Head injuries increased 96 percent in Afghanistan and 150 percent in Iraq

Survival for critically injured casualties increased from 2.2 percent to 39.9 percent in Afghanistan and from 8.9 percent to 32.9 percent in Iraq

The case-fatality rate was cut in half from 2001 to 2017 (Afghanistan from 20 percent to 8.6 percent and Iraq from 20.4 percent to 10.1 percent) even as injury patterns and severity increased

Three key interventions (increased use of tourniquets, increased use of blood transfusion, and more rapid hospital transport times, especially in Afghanistan) were responsible for about a 44 percent of the reduction in mortality. The researchers estimate that 1,622 lives were saved from these interventions.

They also found that without these changes in intervention and policy, an estimated 3,600 additional deaths would have occurred between 2001 and 2017.

Howard says the paper is an extension of his previous work as a DoD epidemiologist and researcher evaluating trauma care practices, like the use of blood transfusions and the transport of casualties to medical treatment facilities.

"My prior work involved evaluating the DoD policy changes mandated by former Secretary of Defense Robert Gates regarding the reduction of transportation times and other trauma care guidelines," said Howard. "In the past, we had to assess these questions with less complete data than what was compiled for this current study."

The UTSA researcher noted that more critically injured military service members reached surgical care, with increased survival rates, which suggests that there were improvements in hospital care as well.

Howard said one of the main goals of this current work is to ensure that the lessons of war are not lost.

"Many of the lessons from the current war had actually been learned before in prior wars," he said. "My colleagues and I are trying to propagate these lessons throughout the scientific and medical literature to inform military trauma care policies for the future."

WASHINGTON, D.C., March 27, 2019 -- Driving across Iowa, Hendrik J. Viljoen, distinguished professor of chemical and biological engineering at the University of Nebraska, noticed that soybean fields were becoming increasingly infested with weeds each season. The culprit is a glyphosate-resistant weed called "palmer amaranth," which is threatening crops in the Midwest.

One pesticide currently used for controlling palmer amaranth is "Dicamba," but it has devastating effects on adjacent areas, harming trees and other crops, because it tends to drift when sprayed during windy conditions.

As a firm believer in the concept that our well-being is closely tied to the health of the crops and animals within our food chain, Viljoen reports in the journal Physics of Fluids, from AIP Publishing, that he was inspired to create a way to spot treat weeds that eliminates any risk of pesticide drift.

"A pesticide solution can be stabilized on a rotating horizontal cylinder/roller akin to a wooden honey dipper," said Viljoen. "Its stability depends on the speed at which the applicator rotates. But the roller is only one part of a bigger process, and there are some technical details regarding the roller that we're also addressing, namely replenishing the pesticide load via wicking from a reservoir at the center of the cylinder."

The manner in which pesticides are applied to plants makes a difference. They can be sprayed from the top of the leaf, rolled on, or delivered by a serrated roller to simultaneously scuff it and apply the pesticide. "We will only arrive at an optimum design if we understand how the active ingredient in the pesticide is delivered to the weed, how it enters the phloem (the plant's vascular system that transports the active ingredient), and the efficacy of its killing mechanism," Viljoen explained.

To apply the pesticide to weeds, rollers can be mounted onto small robots or tractors. "Our current research objective is to develop a system where unmanned aerial vehicles image fields and feed the images to trained neural networks to identify the weeds," he said. "The information on weed species and their exact location will then be used by the robots to spot treat the weeds."

One key finding by Viljoen's group is that the preferred way to operate the roller is to rotate it so that the original velocity at the roller's underside coincides with the direction the robot is traveling. They're now doing experiments to determine any uptake bias for palmer amaranth, as well as exploring making part of the roller's surface serrated. "The idea is to physically penetrate the epidermis to enhance the amount of active ingredient that's delivered to the weed," he said. "To broaden our understanding, we've developed a mathematical model of the transport of the pesticide in the phloem."

The significance of this work is that while there's increasing pressure to produce enough food for a growing population, the current approach is unsustainable. The trend today is to use increased amounts and more potent chemicals to control weeds and invasive species that have developed resistance to previously effective pesticides.

"We must minimize the impact of our practices on the environment and reduce the use of chemicals, their residues and metabolites within our food chain and on the greater ecology," Viljoen said. "Technologies exist that can help us achieve these goals. Precision spray technologies use artificial intelligence to identify weeds and only spray specific areas, but we can do better. We should eliminate the risk of drift and minimize exposure of crops and soil to pesticides."

Developing a drift-free, weed-specific applicator will pave the way for autonomous weed control with smart robots. "At this stage, we can't envision the full utility of these robots, but they offer us the opportunity to survey fields and alert us to disease breakouts, blights or nematodes," said Viljoen. "In the future, the roller -- with some modifications -- could also be used to deliver small RNA molecules to plants. Smaller farm operations that focus on specialized products will likely be the first adopters of the technology."

The dark brown melanin pigment, eumelanin, colors hair and eyes, and protects our skin from sun damage. It has also long been known to conduct electricity, but too little for any useful application - until now.

In a landmark study published in Frontiers in Chemistry, Italian researchers subtly modified the structure of eumelanin by heating it in a vacuum.

"Our process produced a billion-fold increase in the electrical conductivity of eumelanin," say study senior authors Dr. Alessandro Pezzella of University of Naples Federico II and Dr. Paolo Tassini of Italian National Agency for New Technologies, Energy and Sustainable Economic Development. "This makes possible the long-anticipated design of melanin-based electronics, which can be used for implanted devices due to the pigment's biocompatibility."

Eumelanin is a biocompatible conductor

A young Pezzella had not even begun school when scientists first discovered that a type of melanin can conduct electricity. Excitement quickly rose around the discovery because eumelanin - the dark brown pigment found in hair, skin and eyes - is fully biocompatible.

"Melanins occur naturally in virtually all forms of life. They are non-toxic and do not elicit an immune reaction," explains Pezzella. "Out in the environment, they are also completely biodegradable."

Decades later, and despite extensive research on the structure of melanin, nobody has managed to harness its potential in implantable electronics.

"To date, conductivity of synthetic as well as natural eumelanin has been far too low for valuable applications," he adds.

Some researchers tried to increase the conductivity of eumelanin by combining it with metals, or super-heating it into a graphene-like material - but what they were left with was not truly the biocompatible conducting material promised.

Determined to find the real deal, the Neapolitan group considered the structure of eumelanin.

"All of the chemical and physical analyses of eumelanin paint the same picture - of electron-sharing molecular sheets, stacked messily together. The answer seemed obvious: neaten the stacks and align the sheets, so they can all share electrons - then the electricity will flow."

Heat treatment straightens out hair pigment

This process, called annealing, is used already to increase electrical conductivity and other properties in materials such as metals.

For the first time, the researchers put films of synthetic eumelanin through an annealing process under high vacuum to neaten them up - a little like hair straightening, but with only the pigment.

"We heated these eumelanin films - no thicker than a bacterium - under vacuum conditions, from 30 min up to 6 hours," describes Tassini. "We call the resulting material High Vacuum Annealed Eumelanin, HVAE."

The annealing worked wonders for eumelanin: the films slimmed down by more than half, and picked up quite a tan.

"The HVAE films were now dark brown and about as thick as a virus," Tassini reports.

Crucially, the films had not simply been burnt to a crisp.

"All our various analyses agree that these changes reflect reorganization of eumelanin molecules from a random orientation to a uniform, electron-sharing stack. The annealing temperatures were too low to break up the eumelanin, and we detected no combustion to elemental carbon."

A billion-fold increase in conductivity

Having achieved the intended structural changes to eumelanin, the researchers proved their hypothesis in spectacular fashion.

"The conductivity of the films increased billion-fold to an unprecedented value of over 300 S/cm, after annealing at 600°C for 2 hours," Pezzella confirms.

Although well short of most metal conductors - copper has a conductivity of around 6 x 107 S/cm - this finding launches eumelanin well into a useful range for bioelectronics.

What's more, the conductivity of HVAE was tunable according to the annealing conditions.

"The conductivity of the films increased with increasing temperature, from 1000-fold at 200°C. This opens the possibility of tailoring eumelanin for a wide range of applications in organic electronics and bioelectronics. It also strongly supports the conclusion from structural analysis that annealing reorganized the films, rather than burning them."

There is one potential dampener: immersion of the films in water results in a marked decrease in conductivity.

"This contrasts with untreated eumelanin which, albeit in a much lower range, becomes more conductive with hydration (humidity) because it conducts electricity via ions as well as electrons. Further research is needed to fully understand the ionic vs. electronic contributions in eumelanin conductivity, which could be key to how eumelanin is used practically in implantable electronics." concludes Pezzella.

DURHAM, N.C. -- Materials scientists at Duke University have theorized a new "oil-and-vinegar" approach to engineering self-assembling materials of unusual architectures made out of spherical nanoparticles. The resulting structures could prove useful to applications in optics, plasmonics, electronics and multi-stage chemical catalysis.

The novel approach appeared online on March 25 in the journal ACS Nano.

Left to their own tendencies, a system of suspended spherical nanoparticles designed to clump together will try to maximize their points of contact by packing themselves as tightly as possible. This results in the formation of either random clusters or a three-dimensional, crystalline structure.

But materials scientists often want to build more open structures of lower dimensions, such as strings or sheets, to take advantage of certain phenomena that can occur in the spaces between different types of particles. And they're always on the lookout for clever ways to precisely control the sizes and placements of those spaces and particles.

In the new study, Gaurav Arya, associate professor of mechanical engineering and materials science at Duke, proposes a method that takes advantage of the layers formed by liquids that, like a bottle of vinaigrette left on the shelf for too long, refuse to mix together.

When spherical nanoparticles are placed into such a system, they tend to form a single layer at the interface of the opposing liquids. But they don't have to stay there. By attaching "oil" or "vinegar" molecules to the particles' surfaces, researchers can make them float more on one side of the dividing line than the other.

"The particles want to maximize their number of contacts and form bulk-like structures, but at the same time, the interface of the different liquids is trying to force them into two layers," said Arya. "So you have a competition of forces, and you can use that to form different kinds of unique and interesting structures."

Arya's idea is to precisely control the amount that each spherical nanoparticle is repelled by one liquid or the other. And according to his calculations, by altering this property along with others such as the nanoparticles' composition and size, materials scientists can make all sorts of interesting shapes, from spindly molecule-like structures to zig-zag structures where only two nanoparticles touch at a time. One could even imagine several different layers working together to arrange a system of nanoparticles.

In the proof-of-concept paper, the nanoparticles could be made out of anything. Gold or semiconductors could be useful for plasmonic and electrical devices, while other metallic elements could catalyze various chemical reactions. The opposing substrates that form the interface, meanwhile, are modeled after various types of polymers that could also be used in such applications.

"So far in this paper, we have only introduced the assembly approach and demonstrated its potential to create these exotic arrangements that you wouldn't normally get," said Arya. "There are so many more things to do next. For one, we'd like to explore the full repertoire of possible structures and phases researchers could make using this concept. We are also working closely with experimentalists to test the full capabilities of this approach."

SYRACUSE, N.Y. - Tomasz Skwarnicki, professor of physics in the College of Arts and Sciences at Syracuse University, has uncovered new information about a class of particles called pentaquarks. His findings could lead to a new understanding of the structure of matter in the universe.

Assisted by Liming Zhang, an associate professor at Tsinghua University in Beijing, Skwarnicki has analyzed data from the Large Hadron Collider beauty (LHCb) experiment at CERN's Large Hadron Collider (LHC) in Switzerland. The experimental physicist has uncovered evidence of three never-before-seen pentaquarks, each divided into two parts.

"Until now, we had thought that a pentaquark was made up of five elementary particles [called quarks], stuck together. Our findings prove otherwise," says Skwarnicki, a Fellow of the American Physical Society.

Skwarnicki is part of a team of researchers, including members of Syracuse's High-Energy Physics (HEP) Group, studying fundamental particles and forces in the Universe. Most of their work takes place at the CERN laboratory, whose LHC is the biggest, most powerful particle detector in the world.

It is within the LHC that protons are flung together at high energies, only to collide with one another. What lies inside the particles, when cracked open, helps scientists probe the mysteries of the fundamental universe.

Studying proton collisions from 2015-18, Skwarnicki has confirmed the existence of substructure within a pentaquark. The giveaway, he says, was a trio of narrow peaks in the LHC kinematic data.

Each peak refers to a particular pentaquark--specifically, one divided into two parts: a baryon, containing three quarks, and a meson, with two quarks.

A peak also suggests resonance, a short-lived phenomenon during particle decay, in which one unstable particle transforms into several others. Resonance happens when protons (a type of baryon) meet--or, more accurately, glide into one another--during an LHC collision.

What is unique about each of these three pentaquarks is that its mass is slightly lower than the sum of its parts--in this case, the masses of the baryon and meson. "The pentaquark didn't decay by its usual easy, fall-apart process," Skwarnicki says. "Instead, it decayed by slowly and laboriously rearranging its quarks, forming a narrow resonance."

Understanding how particles interact with and bind together is Skwarnicki's specialty. In 2015, he and then Ph.D. student Nathan Jurik G'16, Distinguished Professor Sheldon Stone and Zhang made headlines with their role in LHCb's detection of a pentaquark. Theorized a half century earlier, their discovery drew on LHC data from 2011-12.

LHCb's latest data utilized an energy beam that was nearly twice as strong. This method, combined with more refined data-selection criteria, produced a greater range of proton collisions.

"It also gave us 10 times more data and enabled us to observe pentaquark structures more clearly than before," Skwarnicki says. "What we thought was just one pentaquark turned out to be two narrow ones, with little space between them."

The data also revealed a third "companion" pentaquark. "All three pentaquarks had the same pattern--a baryon with a meson substructure. Their masses were below appropriate the baryon-meson thresholds," he adds.

Skwarnicki's discovery occurred relatively fast, considering that LHCb stopped collecting data less than three months ago.

Eric Sedore, associate CIO for infrastructure services in Information Technology Services (ITS), played a supporting role. His Research Computing Team provided the necessary computer firepower for Skwarnicki to achieve his goals.

In addition to Skwarnicki and Stone, HEP includes Professors Marina Artuso and Steven Blusk and Assistant Professor Matthew Rudolph. The group currently is building an apparatus on campus called the Upstream Tracker (UT), being shipped to and installed at CERN next year as part of a major LHCb upgrade.

"The UT will significantly enhance LHCb, which is composed of about 10 different sub-detectors. I am hopeful that the UT will lead to more discoveries," says Skwarnicki, adding that Artuso and Stone are the UT Project's leader and deputy, respectively.

Skwarnicki is excited about LHCb because it helps explain how the smallest constituents of matter behave. His latest discovery, for instance, proves that pentaquarks are built the same way as protons and neutrons, which are bound together in the nucleus of an atom.

"Pentaquarks may not play a significant role in the matter we are made of," he says, "but their existence may significantly affect our models of the matter found in other parts of the universe, such as neutron stars."

Populations with a high prevalence of AIDS-immunocompromised people are more likely to see the emergence of antibiotic-resistant bacterial infections, according to a study coauthored by researchers at the University of Tennessee, Knoxville, and published in PLOS One.

"People with weakened immune systems are more vulnerable to opportunistic bacterial infections and are therefore frequently prescribed antibiotics to prevent or treat these infections," said Nina Fefferman, a professor in UT's Department of Ecology and Evolutionary Biology and coauthor of the study. "This increases the exposure of those bacteria to antibiotics, giving them more chances to evolve to become resistant to the medication and contributing to the current serious public health threat of drug-resistant diseases."

The research was led by Ashley DeNegre, who at the time of the study was an ecology and evolutionary biology PhD student at Rutgers University-New Brunswick. Kellen Myers, research assistant in UT's Department of Ecology and Evolutionary Biology and the UT-based National Institute of Mathematical and Biological Synthesis, also participated in the research.

For the study, scientists used mathematical models to integrate and extend results from many previous studies to consider the effect on the emergence of antibiotic resistance in two populations: the African nation of Swaziland, where there was a reported HIV/AIDS prevalence of 27.4 percent of the population, and Indonesia, in southeast Asia, where there was a much lower reported HIV/AIDS prevalence of 0.46 percent.

The results provide a better understanding of epidemiological patterns in populations with a high number of immunocompromised people due to AIDS and HIV, with special attention to low-income communities in the developing world.

"This work will hopefully help inform public health decision makers about how antibiotic stewardship should be tailored differently in high-prevalence AIDS-affected communities to help combat the rising global risk of drug-resistant infections," said Fefferman.

COLUMBUS, Ohio - Researchers with The Ohio State University College of Medicine and The Ohio State University Wexner Medical Center have identified a metabolic process in the heart that, if treated, could someday prevent or slow the progression of heart failure.

The American Heart Association journal Circulation published the findings today.

Before any physical signs or symptoms of heart failure are present, the first maladaptive changes occur in cardiac cell metabolism - how the heart fuels itself to pump blood through the body constantly.

"Our hearts burn fuel, much like combustion engines in cars. Instead of gasoline, our heart cells burn fats and a small amount of glucose," said Doug Lewandowski, director of translational research at Ohio State's Dorothy M. Davis Heart and Lung Research Institute. "When our hearts become chronically stressed, they try to adapt, but some of those changes make things worse."

For their research, Lewandowski's team examined both mouse models of heart failure and human heart tissue obtained from heart failure patients before and after heart assist devices were surgically implanted. They found that the amount of a reactive fat compound, called acyl-CoA, is nearly 60 percent lower in failing hearts compared to normal hearts. This disruption in the heart's normal metabolism creates toxic fats that impair the heart's ability to function and pump properly.

Then the team tested mice that overexpressed a gene for a protein called ACSL1, that's known to make acyl-CoA. When exposed to conditions that cause heart failure, the mice kept making normal amounts of acyl-CoA and the extent of heart failure was reduced and delayed.

"By maintaining this fat compound, acyl-CoA, the hearts retained their ability to burn fat and generate energy. Importantly, overexpression of ACSL1 also reduced toxic fats, normalized cell function and reduced the progressive loss of function in the enlarged mouse hearts," said Lewandowski, who is also a professor of internal medicine at Ohio State's College of Medicine.

When the team examined failing human hearts that had the help of a left ventricular assist device (LVAD), they found similar effects - the levels of acyl-CoA had restored to normal when the sick hearts didn't have to work beyond their capacity.

"This tells us there's an important relationship between fat metabolism in the heart and the inability to pump well, and we need to learn more. We believe targeting the normalization of acyl-CoA through gene or drug therapy or, potentially, dietary protocols, is a new approach to explore," Lewandowski said.

"Heart failure is the only form of heart disease that hasn't dropped in 35 years. As findings like these help identify the metabolic underpinnings of the disease, it gives hope for promising new therapies for patients," said Dr. K. Craig Kent, dean of the College of Medicine.

Next, Lewandowski's team wants to explore how normalizing acyl-CoA helps reduce toxic fats and increase protective fats inside the heart. Soon, they hope to use advanced imaging to track fat metabolism and function in patients' hearts.

"We need to understand how we're manipulating the chemical reactions and what exactly is leading to the improvement. Then we can look at whether we can supply the heart with fats, supplements or medications that assist with creating acyl-CoA. Ultimately, it's about trying to prevent or slow the progression toward heart failure," Lewandowski said.

Prostate cancer cells change the behaviour of other cells around them, including normal cells, by 'spitting out' a protein from their nucleus, new research has found.

The tiny pieces of protein are taken up by the other cells, provoking changes that promote tumour growth and - the researchers believe - help the cancer hide from the body's immune system.

The process has been captured for the first time on video by researchers at the University of Bradford and University of Surrey. The research is published today [26 March] in Scientific Reports.

Lead researcher, Professor Richard Morgan from the University of Bradford, said: "For tumours to survive, grow bigger and spread they need to control the behaviour of cancer cells and the normal cells around them and we've found a means by which they do this. Blocking this process could be a potential target for future cancer therapy."

The research focused on a protein called EN2 that has a role in early development of the brain but has also been found at high levels in many types of cancer cells.

The team highlighted the protein using a green florescent tag. The researchers then studied its activity in human prostate cancer cells, normal prostate cells and in bladder cancer, melanoma and leukaemia cells. They found that both cancer and normal cells took up the protein from other cells.

They also did time lapse photography of prostate cancer cells, taking pictures every five minutes for 24 hours. The resulting video shows the cells eject small parts of themselves containing the green florescent protein that are then taken up by otherwise dormant cancer cells, causing them to reactivate, changing shape or fusing together.

Professor Morgan explains: "We think this is significant because cell fusion in cancer is relatively unusual and is associated with very aggressive disease. It can lead to new and unpredictable hybrid cells that are frequently better at spreading to different sites and surviving chemotherapy and radiotherapy."

Molecular analysis of the normal prostate cells showed that take up of EN2 caused them to express a gene called MX2 that generates an anti-viral response.

"We believe the cancer is trying to minimise the chances of the cells around it being infected by a virus, to avoid scrutiny by the immune system," says Professor Morgan.

"This could undermine the effectiveness of immunotherapy treatments, which try to use viruses to kill cancer by stimulating the immune system to attack it."

The researchers were also surprised to find the EN2 protein in the cell membrane as well as in the nucleus - which is very unusual for this type of protein. This provides an opportunity to block its action, and the team were able to identify that part of the protein that was accessible at the cell surface to be a potential target for treatment.

Hardev Pandha, Professor of Medical Oncology at the University of Surrey, says: "This work follows on from earlier studies at Surrey where detection of EN2 in urine, after secretion from prostate cancer cells, was shown to be a robust diagnostic biomarker of prostate cancer. The more we learn about prostate cancer the more that can be done to identify and treat this devastating disease."

In Canada, as in other higher latitudes, there is not enough natural light for production of many greenhouse commodities during the darker months of the year. In these regions, it is necessary for growers of year-round commodities to augment their naturally occurring lighting deficit with artificial lighting to meet their crops' economic minimum lighting requirements.

Until recently, the most economically viable supplemental lighting solution available to greenhouse growers has been high-pressure sodium (HPS) lamps. However, light-emitting diode (LED) technology has improved significantly in recent years and now offers the promise of providing greater energy efficiency and targeted wavelength light in long-lasting fixtures.

Some horticultural LED technologies can dramatically modify intensity and spectral output in real time, increasing their potential to be used for photosynthetic, photomorphogenic, and photoperiodic applications.

Dave Llewellyn, Katherine Schiestel, and Youbin Zheng conducted a study at the University of Guelph to determine the degree to which these LED advancements could benefit greenhouses in the care and proliferation of plants during longer-term exposure to supplemental lighting and to investigate the potential for LED lighting technologies to replace conventional HPS lighting systems. The researchers investigated the production of here varieties of cut gerbera under either HPS or LED supplemental lighting at the same canopy-level intensities.

Their conclusions are detailed in the article "Light-emitting Diodes Can Replace High-pressure Sodium Lighting for Cut Gerbera Production", found in HortScience.

Most of the treatment effects on harvest and postharvest quality metrics of marketable flowers indicated that the LED treatment usually produced higher-quality flowers than the HPS treatment. However, it is unclear whether the magnitude of any of the observed treatment differences would result in economically significant increases in crop productivity or profit.

The authors concluded that LEDs were capable of replacing HPS for supplemental lighting for cut gerbera production during darker periods. Economic factors related to initial cost and potential electricity costs would need to be evaluated on a case-by-case basis to determine which supplemental lighting solution is most appropriate for every grower and production scenario.

It is a commonly held belief that supplemental HPS lighting increases the canopy temperature relative to LED lighting due to inherently higher levels of radiant heat directed from HPS fixtures toward the canopy. Whether added heat is a benefit or a liability depends on the production scenario and environmental control strategy, although foliar heating is often touted as a benefit of HPS lighting.

The researchers discovered that LED lighting is generally more beneficial to greenhouse production than is HPS lighting.