Culture

Some coronaviruses can add to their genetic pool some genes belonging to the host they infected. In this way, they can blend in and be less detectable to the immune system. This discovery was published in the journal Viruses by an Italian research team from the IIS (Italian Healthcare Institute), ISPRA (Institute for Environmental Protection and Research), IZSLER (Italian health authority and research organization for animal health and food safety of Lombardy and Emilia-Romagna) and the University of Bologna.

The outcome of this study demonstrates that coronaviruses encompass a sophisticated evolutionary mechanism and therefore puts increasing emphasis on the importance of studying wildlife diseases. Research in this field is fundamental to understand the functioning of illnesses that can spread from animals to humans so that we can efficiently manage ecosystems and provide a balance between the species inhabiting them", says Mauro Delogu, a researcher at the University of Bologna and one of the authors of this study.

Researchers discovered this while analysing coronaviruses found in specimens of European hedgehogs (Erinaceus europaeus). They classified this strain as EriCoV. These viruses belong to the same strain of Beta-CoV responsible for COVID-19 as well as MERS. However, there is no evidence that they can spread to humans.

These hedgehog coronaviruses are able to steal a gene (CD200) that belongs to the host. When combine with its receptor, this gene allows to prevent an excessive inflammatory response. By incorporating this gene, the virus can hinder the immune defence of the host.

Events like this have never been observed before in coronaviruses. With this evolutionary strategy, coronaviruses can influence the duration of the infection and therefore prolong the time necessary to eliminate the virus, eventually leading to chronic infections. These process goes to the advantage of the virus, as it multiplies its ability to propagate and spread thanks to a specific evolutionary strategy.

"These results pave the way for further investigations into the ability of coronaviruses of interfering with the inhibitory signals of immune cells", continues Delogu. "In this way, coronaviruses can disguise themselves so that it is harder for the immune system of the host to detect, recognize and destroy them".

Findings from a new study on Alzheimer's disease (AD), led by researchers at the University of Saskatchewan (USask), could eventually help clinicians identify people at highest risk for developing the irreversible, progressive brain disorder and pave the way for treatments that slow or prevent its onset.

The research, published in the journal Scientific Reports in early January, has demonstrated that a shorter form of the protein peptide believed responsible for causing AD (beta-amyloid 42, or Aβ42) halts the damage-causing mechanism of its longer counterpart.

"While Aβ42 disrupts the mechanism that is used by brain cells to learn and form memories, Aβ38 completely inhibits this effect, essentially rescuing the brain cells," said molecular neurochemist Darrell Mousseau, professor in USask's Department of Psychiatry and head of the Cell Signalling Laboratory.

Previous studies have hinted that Aβ38 might not be as bad as the longer form, said Mousseau, but their research is the first to demonstrate it is actually protective.

"If we can specifically take out the Aβ42 and only keep the Aβ38, maybe that will help people live longer or cause the disease to start later, which is what we all want."

Aβ42 is toxic to cells, disrupts communication between cells, and over time accumulates to form deposits called plaques. This combination of factors is believed responsible for causing AD. Experts have long thought that all forms of Aβ peptides cause AD, despite the fact that clinical trials have shown removing these peptides from the brains of patients does not prevent or treat the disease.

Mousseau said the idea behind the study was simple enough: If two more amino acids is bad, what about two less?

"We just thought: Let's compare these three peptides, the 40 amino acid one that most people have, the 42 amino acid that we think is involved in Alzheimer's, and this 38 one, the slightly shorter version," said Mousseau, who is Saskatchewan Research Chair in Alzheimer disease and related dementias, a position co-funded by the Saskatchewan Health Research Foundation and the Alzheimer Society of Saskatchewan.

The project confirmed the protective effects of the shorter protein across a variety of different analyses: in synthetic versions of the protein in test tubes; in human cells; in a worm model widely used for studying aging and neurodegeneration; in tissue preparations used to study membrane properties and memory; and in brain samples from autopsies. In the brain samples, they also found that men with AD who had more Aβ42 and less Aβ38 died at an earlier age. The fact that they didn't see this same pattern in samples from women suggests the protein peptide behaves differently in men and women.

The USask team also included Maa Quartey and Jennifer Nyarko from the Cell Signalling Lab (Department of Psychiatry), Jason Maley at the Saskatchewan Structural Sciences Centre, Carlos Carvalho in the Department of Biology, and Scot Leary in the Department of Biochemistry, Microbiology and Immunology. Joseph Buttigieg at the University of Regina and Matt Parsons at Memorial University of Newfoundland were also part of the research team.

While Mousseau wasn't surprised to see that the shorter form prevents the damage caused by the longer version, he said he was a little taken aback at how significant an effect it had.

"As soon as you put Aβ38 into it, it brings it back up to control levels, completely inhibiting the toxic effects of Aβ42. That's what was pleasantly surprising."

On a brisk November morning in 2018, a fire sparked in a remote stretch of canyon in Butte County, California, a region nestled against the western slopes of the Sierra Nevada mountains. Fueled by a sea of tinder created by drought, and propelled by powerful gusts, the flames grew and traveled rapidly. In less than 24 hours, the fire had swept through the town of Paradise and other communities, leaving a charred ruin in its wake.

The Camp Fire was the costliest disaster worldwide in 2018 and, having caused 85 deaths and destroyed more than 18,000 buildings, it became both the deadliest and most destructive wildfire in California's history, two records the fire still holds today.

What made the Camp Fire so devastating? And what lessons can we learn to prevent another disaster of this scale? Researchers at the National Institute of Standards and Technology (NIST) have begun to answer these questions by investigating the conditions leading up to the fire and meticulously reconstructing the sequence of events describing the first 24 hours of its progression. A new report containing the timeline identifies areas where more research is needed to improve life safety and reduce structural losses. It also offers a detailed look at how a large and deadly fire advances -- information that will become increasingly valuable as fire seasons continue to intensify.

"The information we collected on the timeline is extremely powerful by itself, not only for Paradise but for other similar communities, to help them understand what they may encounter and better prepare, whether it is at a community or at the first responder level," said NIST fire protection engineer Alexander Maranghides, who led the timeline reconstruction.

To piece together the puzzle of the Camp Fire, the team carried out discussions with 157 first responders, local officials and utilities personnel who were present during the fire. The team documented sightings of fire or smoke and efforts to fight the fire or evacuate, as well as insights into community preparedness and weather conditions.

The researchers sought to back up observations made during the fire with additional data sources before adding new puzzle pieces to the timeline. With the help of the California Department of Forestry and Fire Protection (CAL FIRE), Paradise Police Department and others, the team gained access to and reviewed large data sets, including radio logs, 911 calls, dashboard and body camera recordings, and drone and satellite images. They also looked to images in social and news media to corroborate the sightings of discussion participants.

By the end of the painstaking process, the authors of the report incorporated more than 2,200 observations into the timeline, which is broken up into 15 separate segments to capture concurrent events throughout different sections of Butte County.

The team's investigation revealed several conditions throughout Butte County that, taken together, created favorable conditions for an inferno. On the day the fire broke out, wind gusts were powerful, blowing up to about 48 kilometers (30 miles) per hour, and were almost exclusively pointed southwest, toward Paradise and the smaller communities of Magalia and Concow. The 200 days of drought preceding the fire had also transformed much of the region's lush terrain into combustible ground.

And perhaps counterintuitively, Maranghides said, the relatively large distance between the fire's origin and the edge of Paradise (about 11 kilometers, or 7 miles) contributed to the massive, 3.2-kilometer (2-mile)-long fire front that crashed into the town.

"If a fire starts far away, upwind, then it has time to develop and expand. By the time it hits the community it is so large and so powerful that it could wipe everything out," Maranghides said. "But if it ignites closer, the fire can be so much smaller. It takes a much smaller bite out of the community, and people may have a fighting chance."

The report indicates that town officials in Butte County went to great lengths to prepare for fires, having cleared vegetative fuels near critical infrastructure and bolstered emergency communications in the weeks and months prior. However, dense vegetation had still accumulated throughout Paradise -- a factor enhanced by the nearly 100 years the town had gone without experiencing a wildfire.

The researchers learned that, although Paradise made resources available for residents to remove trees, many did not take the city up on its offer. One participant in the reconstruction noted that residents were often attracted to the lifestyle of "living in the forest" provided by the town.

With a gamut of unfavorable conditions at play, a spark in the wilderness quickly became a raging inferno.

The fire's siege on Paradise, which ultimately destroyed 85% of the town's buildings, began before its front line reached the city limits. Showers of burning debris were carried by the wind ahead of the main fire into town, where the embers ignited buildings and vegetation, riddling the town with dozens of smaller fires that ate up precious firefighting resources.

Propelling the Camp Fire's structure-destroying spree were fires that spread within and between plots of land, or parcels, rather than from the fire front. Sources such as burning sheds, plants, vehicles and neighboring houses caused many buildings to catch fire, either through direct contact with flames or embers generated in parcels.

Paradise's defenses quickly fell once the fire front reached town. The incident commander leading the emergency response recognized the fire's speed and intensity and ordered his personnel to abandon all firefighting efforts just 45 minutes after the fire arrived. "Save lives, keep evacuation moving," the incident commander said over the radio.

Although the focus of emergency response narrowed on saving lives, evacuation efforts were stifled by burnovers -- life-threatening events in which residents or first responders are overrun by flames, cutting them off from escape routes. Across Paradise and Concow there were 19 burnovers at least, some of which involved downed power lines or flaming vegetation that blocked off roads, causing gridlock and putting lives in danger.

In the past, recorded burnovers were sparse, with reports attributing few or none to most fires. Hardly any have been scrutinized as heavily as the Camp Fire, however, which could partially explain the event's high number of documented burnovers. Another critical contributor was likely Paradise's heavily wooded nature, Maranghides said.

The abundance of burnovers during the Camp Fire may not be an isolated event, but part of a larger trend, particularly for communities where vegetative fuels have built up over many years.

"The significant activity we've experienced in the last few years may indicate that burnovers are becoming more frequent than they used to be," said CAL FIRE chief Steven Hawks, a co-author of the report. "My sense is that because fires are burning so fast now, there is more potential for people to become trapped."

With this report, NIST has shone light on the many aspects of the Camp Fire's multipronged attack. Research into these threats could fill critical knowledge gaps, paving the way for science-based codes, standards and practices that could help communities outsmart fires.

What's urgently needed, the authors write, are methods of capturing the severity of burnovers and a better understanding of how they occur in the first place. Studies in this area could make way for guidelines on reducing their likelihood and protecting evacuation routes.

As for buildings, there are already two known options for increasing their chances of surviving a wildfire. The first is to make sure combustible items within a parcel (plants, sheds, etc.) are not too close to a structure, and the second is to increase the fire resistance of a structure's materials. But striking a cost-effective balance between the two is difficult with the limited information on how various fuel sources threaten buildings.

"We need to improve our understanding at the parcel level because it's the parcel-level exposures that drive the building's survivability," Maranghides said. "You cannot just look at the building in absence of what's around it."

Once researchers can put numbers to the behavior of embers and combustibles in parcels, it may become more clear what a particular building needs in terms of spacing and hardening to hold up to a wildfire.

City officials could use the report's timeline for emergency planning as well. By having a detailed description of events such as burnovers in front of them, members of city councils or public works departments in wildfire-prone regions could evaluate their own emergency plans and potentially identify vulnerabilities.

There is currently no standard method of comparing the wildfire hazards of communities. So, although the researchers could draw individual similarities between Paradise and other communities in Northern California, they were unsure how the town compared as a whole. The team aimed to bridge this gap by developing a framework in the form of a document encouraging city officials to record specific information on fuels, population, emergency notifications and other aspects of the community.

If adopted and employed statewide in California and in other wildfire-prone areas, the framework, which appears in the report, could reveal areas most at risk and worthy of attention and resources, Maranghides said.

In the hands of first responders, the new report could become valuable training material. Using data on how quickly and intensely the fire grew, commanders could build tabletop exercises to practice deploying firefighting resources to counter its spread and save lives.

An event on the scale of the Camp Fire makes it clear that action is needed at all levels to protect communities from wildfires, Hawks said. And that need is perhaps more urgent now than ever.

"Going forward, there's no reason to believe that fire activity and severity is going to lessen anytime soon," Hawks said. "We're never going to get rid of wildfires, natural or human-caused. But we can learn how to live with and work together to mitigate them."

The full report is now available, along with several maps portraying the fire spread. The timeline of fire progression will form the basis for subsequent reports on evacuation and emergency response during the Camp Fire that the NIST team plans to publish in the coming months.

An unusual biologically active porphyrin compound was isolated from seabed dweller Ophiura sarsii. The substance might be used as an affordable light-sensitive drug for innovative photodynamic therapy and for targeted treatment of triple-negative breast cancer and some other cancers. Researchers from the School of Biomedicine of Far Eastern Federal University (FEFU) and the University of Geneva reported the findings in Marine Drugs.

The seabed dweller Ophiura sarsii, the source of the new compound, was isolated at a depth of 15-18 meters in Bogdanovich Bay, Russky Island (Vladivostok, Russia). Ophiuras may resemble a starfish, however, these are two completely different classes, belonging to the type of echinoderms. Recognized back in 1855, O. sarsii is an abundant inhabitant of ocean shallows and at depths. This abundance renders the species as a natural source of a strong medicinal compound with little risk of the species extinction. It's also easy to collect compared to the deep-sea species of this group of marine life.

Initially, biologically active molecules from O. sarsii were scrutinized for the ability to suppress the development of triple-negative breast cancer cells. After the antitumor effect confirmed positive, scientists became interested in the compound's formula. They were surprised when it turned out to represent a variant of a compound class known as porphyrins, that had previously been obtained only through complex artificial synthesis. From Ophiuras, it in contrast can be obtained in just one step without expensive technological processes.

"The compound belongs to the group of porphyrins, substances that previously have never been found in the Ophiurae. It has not been previously identified in natural sources but instead has been only obtained through organic synthesis. In photodynamic therapy, porphyrins can be applied as photosensitizers, agents that, when induced by laser, release active oxygen that kills tumor cells, minimally affecting the rest of the body. Photodynamic therapy was introduced to treatm cancer of the bladder, esophagus, lungs, and basal cell carcinoma. Now it is also used for various dermatological procedures". Explains Vladimir Katanaev, the leading author of the study, Head of the Laboratory of the Pharmacology of Natural Compounds, FEFU. "Artificial synthesis of photosensitizers and, in particular, porphyrin is quite expensive. That makes scientists around the world look for new sources of such compounds. We managed to obtain one by a simple method from a natural source. This discovery might further the biomedicine and, in particular, the developments in the field of targeted anti-cancer therapy based on natural compounds."

The study includes evaluation data for the market of photodynamic therapy pointing out that it could reach nearly $12 billion by 2027. While so, the market depends on a very limited set of therapeutic compounds. New sources of photosensitizers will help expanding the therapy options and make the procedure more affordable.

"Molecules of the porphyrin group were also detected in other marine organisms. For example, in dinoflagellates, the algae that are to blame for the notorious red tides that kill all life. However, a medical version of the substance from them was never attempted to be developed. If and when the medical efficacy of the substance we have discovered is proven, it is quite possible to scale up its production from Ophiurae via mariculture methods, or by optimizing the existing synthesis methods on the basis of the natural compounds to simplify and make them cost-effective," says Vladimir Katanaev.

Natural compounds from Ophiura also demonstrate a strong potential of blocking the WNT-signaling pathway in tumor cells. This pathway' activity is extremely important at the stage of human embryonic development, but their restart in adults is one of the reasons for the development of a triple-negative form of breast cancer, colon cancer, and some other tumors. Scientists will investigate the anti-WNT potential of new compounds from Ophiurae at the next stages.

It remains to be seen whether O. sarsii produces the porphyrin compound on their own or resulting from certain dietary "preferences." Additionally, researchers are interested if the species contains the compound throughout its vast habitat, or it is just a local phenomenon in the region of the Russky Island.

Earlier, scientists from the FEFU School of Biomedicine found that human RSP-12 protein might be a potential target for anti-cancer therapy. For the study, they used the developing eye of Drosophila as a test platform.

COLUMBUS, Ohio - We know that what happens in the mouth doesn't stay in the mouth - but the oral cavity's connection to the rest of the body goes way beyond chewing, swallowing and digestion.

The healthy human oral microbiome consists of not just clean teeth and firm gums, but also energy-efficient bacteria living in an environment rich in blood vessels that enables the organisms' constant communication with immune-system cells and proteins.

A growing body of evidence has shown that this system that seems so separate from the rest of our bodies is actually highly influential on, and influenced by, our overall health, said Purnima Kumar, professor of periodontology at The Ohio State University, speaking at a science conference this week.

For example, type 2 diabetes has long been known to increase the risk for gum disease. Recent studies showing how diabetes affects the bacteria in the mouth help explain how periodontitis treatment that changes oral bacteria also reduces the severity of the diabetes itself.

Connections have also been found between oral microbes and rheumatoid arthritis, cognitive abilities, pregnancy outcomes and heart disease, supporting the notion that an unhealthy mouth can go hand-in-hand with an unhealthy body.

"What happens in your body impacts your mouth, and that in turn impacts your body. It's truly a cycle of life," Kumar said.

When the American Association for the Advancement of Science (AAAS) themed this year's annual meeting around dynamic ecosystems, Kumar saw an opportunity to put the mouth on the map, so to speak, as a vibrant microbial community that can tell us a lot about ourselves.

"What is more dynamic than the gateway to your body - the mouth? It's so ignored when you think about it, and it's the most forward-facing part of your body that interfaces with the environment, and it's connected to this entire tubing system," she said. "And yet we study everything but the mouth."

Kumar organized a session at the AAAS meeting today (Feb. 8, 2021) that she titled "Killer Smile: The Link Between the Oral Microbiome and Systemic Diseases."

The oral microbiome refers to the collection of bacteria - some helpful to humans and some not - that live inside our mouths.

Kumar has led and collaborated on recent research further explaining the link between oral health and type 2 diabetes, which was first described in the 1990s. She was the lead author of a 2020 study that compared the oral microbiomes of people with and without type 2 diabetes and how they responded to nonsurgical treatment of chronic periodontitis.

The team found that periodontitis allows bacteria - rather than the human host - to take the reins in determining the mix of microbes and inflammatory molecules in the mouth. Treating the gum disease led to eventual restoration of a normal host-microbiome relationship, but it happened more slowly in people with diabetes.

"Our studies have led up to the conclusion that people with diabetes have a different microbiome from people who are not diabetic," Kumar said. "We know that changing the bacteria in your mouth and restoring them back to what your body knows as healthy and friendly bacteria actually improves your glycemic control."

Though there remains a lot to learn, the basics of these relationship between the oral microbiome and systemic disease have become clear.

Oral bacteria use oxygen to breathe and break down simple molecules of carbohydrates and proteins to stay alive. Something as simple as not brushing your teeth for a few days can set off a cascade of changes, choking off the oxygen supply and causing microbes to shift to a fermentative state.

"That creates a septic tank, which produces byproducts and toxins that stimulate the immune system," Kumar said. An acute inflammatory response follows, producing signaling proteins that bacteria see as food.

"Then this community - it's an ecosystem - shifts. Organisms that can break down protein start growing more, and organisms that can breathe in an oxygen-starved environment grow. The bacterial profile and, more importantly, the function of the immune system changes," she said.

The inflammation opens pores between cells that line the mouth and blood vessels get leaky, allowing what have become unhealthy bacteria to enter circulation throughout the body.

"The body is producing inflammation in response to these bacteria, and those inflammatory products are also moving to the bloodstream, so now you're getting hammered twice. Your body is trying to protect you and turning against itself," Kumar said. "And these pathogens are having a field day, crossing boundaries they were never supposed to cross."

The exact mechanisms of the links between the oral microbiome and specific diseases are complex and still being investigated, but the secret to a healthy mouth is no secret at all: Prevention of oral disease is as simple as brushing and flossing, and visiting the dentist twice a year for a professional cleaning, Kumar said.

The Office of the U.S. Surgeon General announced in 2018 that it had commissioned an update to its 2000 report on oral health, which was the first to be published on the topic.

Kumar said the national emphasis on oral health as an integral element of overall well-being bolsters her argument that the mouth should be an "equal opportunity player" in determinants of health.

"Putting the mouth back into the body - that's my goal here," she said.

DURHAM, N.C. -- The world's most technologically advanced robots would lose in a competition with a tiny crustacean.

Just the size of a sunflower seed, the amphipod Dulichiella cf. appendiculata has been found by Duke researchers to snap its giant claw shut 10,000 times faster than the blink of a human eye.

The claw, which only occurs on one side in males, is impressive, reaching 30% of an adult's body mass. Its ultrafast closing makes an audible snap, creating water jets and sometimes producing small bubbles due to rapid changes in water pressure, a phenomenon known as cavitation.

Three things make this ultra-fast movement unique said Sarah Longo, who studied the amphipods as part of her postdoctoral studies at Duke: the amphipods' really small size, the fact that they live in water, and the repeatability of their movements.

Other animals have comparable accelerations, but none has the same set of constraints: the jaws of trap-jaw ants are faster, but move through air. Mantis shrimp are comparably fast and aquatic, but much larger. Jellyfish stinging cells are ejected with higher acceleration, but only once.

"We take repeatability for granted in biology," said Longo, a visiting assistant professor at Towson University and first author on the paper. "Lots of ultrafast movements are not repeatable, such as ballistic seed ejection by plants. Some of these seeds are going even faster than this amphipod and traveling an impressive distance, but they are one-off events."

Repeatability is a big challenge for engineering, said Longo. Parts that move very fast often become disconnected, break, or have to be manually reloaded.

"The fact that this movement is repeatable is marking an interesting boundary," Longo said. "There appears to be a cutoff where you are going so fast that you inherently have to give up repeatability. These animals are showing how fast you can actually go without breaking."

"These organisms are doing things with capabilities that we currently cannot build. Engineered systems that can be used repeatedly are several orders of magnitude slower and bigger than these animals," said Sheila Patek, a professor at Duke Biology and senior author on the paper.

The potential behind ultrafast movements is so great that the Army is paying attention to these small animals.

"Small organisms achieve incredible actuation authority with no adherence to the rules we use for engineering using motors, springs, and structures," said Samuel Stanton, program manager, Army Research Office, an element of the U.S. Army Combat Capabilities Development Command's Army Research Laboratory. "There is a myriad of organisms from which we can learn a great deal for future Army small robotics and this research team is discovering a whole new set of rules we should be following."

"There is a lot that biology can tell us," Longo said. "Evolution has had millions of years to come up with solutions to all sorts of problems that we can't even articulate yet."

This discovery is surprising given that these amphipods are very common, being found all over the Eastern coast of North America.

"The majority of biologists tend not to pay much attention to amphipods, because they are so small," said Rich Palmer, a professor at the University of Alberta and co-author on the paper. "We would never have guessed that they make these ultra fast movements."

Palmer had his attention drawn to these animals when colleagues mentioned in a casual conservation that certain amphipods made snapping noises.

Intrigued, he suggested to Patek a trip to the Duke Marine Laboratory, in Beaufort, NC, in order to investigate these snaps further. To everyone's surprise and delight, they found thousands of these ultra fast animals right off the docks.

"Hanging in debris, off a dock, in some junky algae, are creatures whose capabilities we didn't even know existed," says Patek. "This is what happens if you take a second look at a weird animal and just take the time to figure out what they are doing."

"You have to be curious, you have to be brave, and you can't be afraid of wasting time," said Palmer. "That is how amazing discoveries are made."

Ebola and Marburg are among the most deadly viruses, with mortality rates from these infections ranging from 25% to 90%. While no drugs currently are available on the market to prevent infection from these viruses -- they belong to a category of viruses called filoviruses, which are known to cause hemorrhagic fever -- researchers have identified a few small drug molecules that can block filoviruses from infecting cells by occupying a single site on a glycoprotein in the virus.

Now, researchers at the University of Illinois Chicago have identified a second site on the filovirus glycoprotein to which small drug molecules can bind and prevent infection. The researchers say that small drug molecules that block both glycoprotein sites may be more effective and reduce the risk of side effects.

These findings are reported in the journal PLOS Pathogens.

"We need to identify how these filoviruses get into cells as a means to help us identify or develop drugs that can prevent infection," said Lijun Rong, UIC professor of microbiology and immunology at the College of Medicine and a corresponding author of the paper. "Even though at the moment Ebola and Marburg are not in the news that often, having drugs in our arsenal in case of a flare-up is invaluable. These viruses also mutate constantly, so having a better understanding of how they work will let us develop next-generation viral inhibitors."

Rong's group and his collaborators, led by Rui Xiong, UIC research assistant professor of pharmaceutical sciences at the College of Pharmacy, identified the second glycoprotein binding site by pairing the virus with hundreds of different small drug molecules thought to possibly have an effect on viral entry into cells. Several of the drugs were able to prevent viral entry.

Through a series of experiments using molecular, biophysical and structural experimental techniques, they were able to look more closely at how these drugs were interacting with the virus. They found that the drugs were binding to a previously unknown site on the viral surface glycoprotein required for cell infection.

"The good news is that there are already drugs approved by the FDA that can bind to the new site we identified," Rong said. "If we can give drugs that bind to the site we newly identified and the site previously identified, it can help prevent viral infection with lower doses of each drug. Interfering with both sites on the viral surface glycoprotein, it also reduces the chances of the glycoprotein mutating to the point that it escapes the effect of the drug combination and is able to infect cells once again."

(Santa Barbara, Calif.) -- Researchers in the labs of Christopher Bates, an assistant professor of materials at UC Santa Barbara, and Michael Chabinyc, a professor of materials and chair of the department, have teamed to develop the first 3D-printable "bottlebrush" elastomer. The new material results in printed objects that have unusual softness and elasticity -- mechanical properties that closely resemble those of human tissue.

Conventional elastomers, i.e. rubbers, are stiffer than many biological tissues. That's due to the size and shape of their constituent polymers, which are long, linear molecules that easily entangle like cooked spaghetti. In contrast, bottlebrush polymers have additional polymers attached to the linear backbone, leading to a structure more akin to a bottle brush you might find in your kitchen. The bottlebrush polymer structure imparts the ability to form extremely soft elastomers.

The ability to 3D-print bottlebrush elastomers makes it possible to leverage these unique mechanical properties in applications that require careful control over the dimensions of objects ranging from biomimetic tissue to high-sensitivity electronic devices, such as touch pads, sensors and actuators.

Two postdoctoral researchers -- Renxuan Xie and Sanjoy Mukherjee -- played key roles in developing the new material. Their findings were published in the journal Science Advances.

Xie's and Mukherjee's key discovery involves the self-assembly of bottlebrush polymers at the nanometer length scale, which causes a solid-to-liquid transition in response to applied pressure. This material is categorized as a yield-stress fluid, meaning it begins as a semi-soft solid that holds its shape, like butter or toothpaste, but when sufficient pressure is applied, it liquefies and can be squeezed through a syringe. The team exploits this property to create inks in a 3D-printing process called direct ink writing (DIW).

The researchers can tune the material to flow under various amounts of pressure to match the desired processing conditions. "For instance, maybe you want the polymer to hold its shape under a different level of stress, such as when vibration is present," says Xie. "Our material can hold its shape for hours. That's important, because if the material sags during printing, the printed part will have poor structural stability."

Once the object is printed, UV light is shined onto it to activate crosslinkers that Mukherjee synthesized and included as a part of the ink formulation. The crosslinkers can link up nearby bottlebrush polymers, resulting in a super-soft elastomer. At that point, the material becomes a permanent solid -- it will no longer liquefy under pressure -- and exhibits extraordinary properties.

"We start with long polymers that are not crosslinked," said Xie. "That allows them to flow like a fluid. But, after you shine the light on them, the small molecules between the polymer chains react and are linked together into a network, so you have a solid, an elastomer that, when stretched, will return to its original shape."

The softness of a material is measured in terms of its modulus, and for most elastomers, it is rather high, meaning their stiffness and elasticity are similar to those of a rubber band. "The modulus of our material is a thousand times smaller than that of a rubber band," Xie notes. "It is super-soft -- it feels very much like human tissue -- and very stretchy. It can stretch about three to four times its length."

An Accidental Ink

Mukherjee discovered the material by accident, while trying to develop a material for a different project, one that would increase the amount of charge that can be stored by an actuator. When the elastomer came to Xie for characterization, he knew immediately that it was special. "I could see right away that it was different, because it could hold its shape so well," he recalled.

"When we saw this really well-defined yield stress, it dawned on everyone collectively that we could 3D-print it," Bates said, "and that would be cool, because none of the 3D-printable materials we know of have this super-soft property."

Bottlebrush polymers have been around for more than twenty years. But, Bates said, "The field has exploded in the past ten years thanks to advances in synthetic chemistry that provide exquisite control over the size and shape of these unique molecules.

"These super-soft elastomers might be applicable as implants," he added. "You may be able to reduce inflammation and rejection by the body if the mechanical properties of an implant match native tissue."

Another important element of the new material is that it is pure polymer, Chabinyc noted.

"There's no water or other solvent in them to artificially make them softer," he said.

To understand the importance of having no water in the polymer, it's helpful to think of Jell-O, which is mostly water and can hold its shape, but only as long as the water remains inside. "If the water went away, then you'd just have a shapeless pile of material," said Chabinyc. "With a conventional polymer, you must figure out how to keep the right amount of water in it to maintain its structure, but this new material is all solid, so it will never change."

Moreover, the new material can be 3D-printed and processed without solvent, which is also unusual. "People often add solvent to liquify a solid so that it can be squeezed out of a nozzle," said Xie, "but if you add solvent, it has to evaporate after printing causing the object to change its shape or crack."

Mukherjee added, "We wanted the material and the printing process to be as clean and as easy as possible, so we played a chemistry trick with solubility and self-assembly, which enabled the solvent-free process. The fact that we don't use solvent is a tremendous advantage."

Alexandria, Va., USA -- High-volume aspirators are recommended in dental clinics during the COVID-19 pandemic, but the study "SARS-CoV-2 Seropositivity Among Dental Staff and the Role of Aspirating Systems" published in the JDR Clinical & Translational Research (JDR CTR), shows that the type of aspirating system significantly affects the incidence of SARS-CoV-2 infection among dental specialists.

In this retrospective cohort study of 157 healthcare workers in Ekaterinburg, Russia, data on the seroprevalence of COVID-19 from dental clinics using three different types of aspirating systems were compared. Clinic A and B used a V6000 aspirating system with a vacuum controller and high-efficiency particulate air (HEPA) filters, but the aspirating system in clinic A functioned in dry mode and the system in clinic B function in semi-dry mode. Clinic C used the VS900 system which discharges air into the dental operatory, closely resembling natural dispersion, and no HEPA filter.

The estimated prevalence of SARS-CoV-2 infection was 11.5% (19 HCWs) across all clinics over the 5-month period (May to August 2020). The results show that the prevalence of SARS-CoV-2 infection was significantly higher in clinic C, which did not utilize HEPA filters, and was significantly lower in clinic A, which did utilize HEPA filters and operated in dry mode. In dry suction systems, the separation of aspirated fluids from the air occurs at every treatment unit, whereas in semi-dry suction systems the separation occurs via a central separation unit connected to multiple treatment units.

"No comparative studies have investigated the effects of the type of aspirating system on the risk of SARS-CoV-2 infection among dentists and dental assistants," said JDR CTR Editor-in-Chief Jocelyne S. Feine, McGill University, Montréal, Quebec, Canada. "Based on the results of this pilot study, we recommend the use of aspirating systems installed with HEPA filters that evacuate and dissipate aerosols into specialized areas. Studies that provide a deeper understanding of this topic are warranted."

Systems designed to detect deepfakes --videos that manipulate real-life footage via artificial intelligence--can be deceived, computer scientists showed for the first time at the WACV 2021 conference which took place online Jan. 5 to 9, 2021.

Researchers showed detectors can be defeated by inserting inputs called adversarial examples into every video frame. The adversarial examples are slightly manipulated inputs which cause artificial intelligence systems such as machine learning models to make a mistake. In addition, the team showed that the attack still works after videos are compressed.

"Our work shows that attacks on deepfake detectors could be a real-world threat," said Shehzeen Hussain, a UC San Diego computer engineering Ph.D. student and first co-author on the WACV paper. "More alarmingly, we demonstrate that it's possible to craft robust adversarial deepfakes in even when an adversary may not be aware of the inner workings of the machine learning model used by the detector."

In deepfakes, a subject's face is modified in order to create convincingly realistic footage of events that never actually happened. As a result, typical deepfake detectors focus on the face in videos: first tracking it and then passing on the cropped face data to a neural network that determines whether it is real or fake. For example, eye blinking is not reproduced well in deepfakes, so detectors focus on eye movements as one way to make that determination. State-of-the-art Deepfake detectors rely on machine learning models for identifying fake videos.

The extensive spread of fake videos through social media platforms has raised significant concerns worldwide, particularly hampering the credibility of digital media, the researchers point out. ""If the attackers have some knowledge of the detection system, they can design inputs to target the blind spots of the detector and bypass it," " said Paarth Neekhara, the paper's other first coauthor and a UC San Diego computer science student.

Researchers created an adversarial example for every face in a video frame. But while standard operations such as compressing and resizing video usually remove adversarial examples from an image, these examples are built to withstand these processes. The attack algorithm does this by estimating over a set of input transformations how the model ranks images as real or fake. From there, it uses this estimation to transform images in such a way that the adversarial image remains effective even after compression and decompression.??

The modified version of the face is then inserted in all the video frames. The process is then repeated for all frames in the video to create a deepfake video. The attack can also be applied on detectors that operate on entire video frames as opposed to just face crops.

The team declined to release their code so it wouldn't be used by hostile parties.

High success rate

Researchers tested their attacks in two scenarios: one where the attackers have complete access to the detector model, including the face extraction pipeline and the architecture and parameters of the classification model; and one where attackers can only query the machine 

learning model to figure out the probabilities of a frame being classified as real or fake. In the first scenario, the attack's success rate is above 99 percent for uncompressed videos. For compressed videos, it was 84.96 percent. In the second scenario, the success rate was 86.43 percent for uncompressed and 78.33 percent for compressed videos. This is the first work which demonstrates successful attacks on state-of-the-art deepfake detectors.

"To use these deepfake detectors in practice, we argue that it is essential to evaluate them against an adaptive adversary who is aware of these defenses and is intentionally trying to foil these defenses,"� the researchers write. "We show that the current state of the art methods for deepfake detection can be easily bypassed if the adversary has complete or even partial knowledge of the detector."

To improve detectors, researchers recommend an approach similar to what is known as adversarial training: during training, an adaptive adversary continues to generate new deepfakes that can bypass the current state of the art detector; and the detector continues improving in order to detect the new deepfakes.

The Atala butterfly (Eumaeus atala) and its five closest relatives in the genus Eumaeus like to display their toxicity. This sextet's toxicity comes from what they eat as caterpillars: plants called cycads that have been around since before dinosaurs roamed the Earth and contain a potent liver toxin called cycasin.

Because they are filled with poison, Eumaeus are big, gaudily iridescent and flap about like they have no place to go. Even their caterpillars are conspicuous, congregating in groups to munch cycad plants all while sporting flashy red and gold coloration. Their ostentatious qualities all signal to predators that they are a not a good meal; in nature, being toxic protects organisms from being attacked if their predators know it.

Now, new research led by the Smithsonian's National Museum of Natural History butterfly curator Bob Robbins tells the evolutionary tale of how these six poisonous butterflies gained their toxin-laced defenses as well as the bold colors and behaviors that tell all would-be predators to steer clear.

"Butterflies don't have teeth or claws to defend themselves," Robbins said. "But they use their wing color and flight behavior as a signal of their unsavory qualities to predators, sometimes deceptively and in others truthfully, as in the case of Eumaeus. With the newfound ability to sequence genomes with relative ease, we have the opportunity to look at that in great detail for the first time."

The paper, published in the Feb. 8 issue of the journal the Proceedings of the National Academy of Sciences, relies on 46 sequenced butterfly genomes, including all six members of Eumaeus and a number of members of the 1,000-strong group of butterflies Eumaeus is related to--the hairstreaks.

Hairstreaks occur widely in North and South America, and almost all of them are small, evasive and nondescript. Their caterpillars, which typically eat a varied diet of flowering plants, usually are well camouflaged and do not congregate in groups. Eumaeus' ranks are notable exceptions; so much so that for years some researchers suggested that Eumaeus might not even be hairstreaks at all. In addition, because of cycads' ancient evolutionary history, most scientists had assumed that the six members of Eumaeus developed their tolerance for cycasin and their conspicuousness a very long time ago in their evolutionary history.

To settle the matter, Robbins and his colleagues set about sequencing the genomes of Eumaeus' six members and a bevy of other hairstreaks around three years ago, drawing on the wealth of diverse specimens held in the museum's collections as well as some samples from wild butterflies. Those results definitively showed that Eumaeus butterflies were not an ancient evolutionary departure from the rest of the hairstreaks. In fact, they are closely related to a pair of rather typical genera called Theorema and Mithras.

The results also showed that the ability to eat poisonous cycads was such a boon to Eumaeus that it spurred a frenzy of rapid evolutionary change that outpaced all other hairstreaks. The team also learned that Eumaeus had split in two evolutionary lines after they began to eat cycads, so they were able to analyze the evolutionary dash twice, including the marked genetic similarities the two lineages had in responding to their new poisonous diet.

When the team started analyzing the Eumaeus genomes, they saw a striking amount of genetic change to parts of these butterflies' genomes related to building various types of proteins. To narrow down whether these proteins might be related to eating cycads, the researchers compared the Eumaeus genomes to butterflies in Theorema, their closest non-toxic relatives, which have camouflaged, solitary caterpillars that eat a standard range of flowering plants.

Theorema also had some regions of fast evolving DNA that coded the construction of various proteins. When Robbins and his co-authors compared the two genomes they discarded any regions of rapid change that overlapped between the two to hopefully isolate the genetic changes involved in coping with the cycad's toxins.

"Sure enough, there was a core group of proteins that had gone through a lot of rapid change in Eumaeus but not in the hairstreaks that don't eat cycads," Robbins said. "When we looked at the function of the proteins that changed quickly, it was very strong on the proteins that would destroy cells, proteins that would remove dead cell debris and proteins to create new cells."

Robbins said these proteins are exactly what an organism would need if it had to find a way to safely ingest cycasin-type toxin. "If the cycad toxins were killing cells at high rates, the organism would need to break those cells down, clean them out and then very rapidly make new ones to avoid any ill effects," he said.

This research details the evolution of a toxic defense mechanism in these six butterfly species and the genetic consequences that result. Though the emergence of warning coloration and lazy flight might not be as easy to pick out in Eumaeus' genes, it appeared in parallel with the change in diet.

Numerous butterfly species have evolved to make themselves less attractive to predators by eating toxic substances, and Robbins said this evolutionary accounting of how Eumaeus honed its defense could offer an evolutionary model for how species adapt to living with these toxins inside their bodies.

PITTSBURGH, Feb. 8, 2021 - With the aid of sophisticated machine learning, researchers at UPMC and the University of Pittsburgh School of Medicine demonstrated that a tool they developed can rapidly predict mortality for patients facing transfer between hospitals in order to access higher-acuity care. This research, published today in PLOS One, could help physicians, patients and their families avoid unnecessary hospital transfers and low-value treatments, while better focusing on the goals of care expressed by patients.

Each year, nearly 1.6 million patients--or as much as 3.5% of all inpatient admissions--are transferred from one hospital to another to access specialized care for complex conditions. "However, securing these services often requires burdensome travel and reduced community support for patients and their families. While some may recover from the acute illness, many others realize little benefit in terms of improved outcomes," said Daniel E. Hall, M.D., corresponding author of the study, as well as medical director of high-risk populations and outcomes at the UPMC Wolff Center and associate professor of surgery at Pitt's School of Medicine.

To address this gap in the coordination of patient care, which currently relies on the ad hoc judgement of bedside clinicians, Hall and his team developed a real-time tool that can predict mortality outcomes for patients at the time of hospital transfer and deliver these results to physicians in less than five minutes.

Using data from nearly 21,000 patients aged 18 and older who were transferred to a UPMC hospital during a 12-month period, the researchers developed and validated a mortality risk-assessment tool dubbed "SafeNET" (Safe Nonelective Emergent Transfers). After studying other mortality risk models currently used in hospital intensive care unit and admission settings, Hall and his team constructed a list of 70 independent variables used in one or more of these models, including patient demographics, vital signs, lab tests and other factors.

They then analyzed UPMC billing data and inpatient electronic health records to determine if these variables were recorded by the receiving hospital and focused only on those available within three hours of transfer. That culled the list to 54 of the 70 variables. Using guided machine learning on both training and test sets of the data, the team ultimately developed their SafeNET algorithm composed of 14 variables that reliably and rapidly predict in-hospital, 30-day and 90-day mortality for transferred patients. They also compared SafeNET's predictive ability to another tool used for patients with infection--and found that the SafeNET algorithm was more accurate and could be used in a more general patient population.

"Our overarching goal was to provide much-needed information to front-line physicians to trigger and inform shared decisions about the highest risk patients," said Hall. "This tool could help to direct additional resources to these patients to ensure that the plan of care is consistent with the patient's values and goals. Frequently, transferred patients and their families don't understand the severity of the illness they are facing and have unrealistic expectations about the outcomes that a transfer for higher-level care will produce."

By piloting the tool in three hospitals within the UPMC system, the researchers built SafeNET as an easily accessible, web-based application. SafeNET guided users to enter as many of the variables as were immediately available and then generated a predicted mortality risk--doing so accurately even when at least one variable was missing, which occurred more than half the time.

Hall cautions that further work is needed before widely deploying SafeNET. Since the data were restricted to a single, multi-hospital system, the findings may not generalize to other care settings. And some of the information that feeds the algorithm may be subject to bias.

Work is ongoing at UPMC to build care pathways triggered by the SafeNET score that direct needed resources to patients at greatest risk of poor outcomes. For instance, the tool is being used in pilot studies to initiate goal-clarification conferences among clinicians contemplating a transfer between hospitals, and to deliver remote, video-conferenced palliative care services to patients being considered for transfer.

"SafeNET is not meant to supersede clinical judgement," Hall noted. "Instead, its intent is to trigger a 'pause' so that clinicians are better prepared to inform and guide patients and families, preferably before a critically ill patient is transferred. We know that patients or their surrogates who participate in conversations with physicians about their values tend to receive care that is consistent with their preferences. SafeNET may be an effective and inexpensive tool for facilitating those important conversations."

Economic growth is often prescribed as a sure way of increasing the well-being of people in low-income countries, but a study led by McGill and the Institute of Environmental Sciences and Technologies at the Universitat Autònoma de Barcelona (ICTA-UAB) suggests that there may be good reason to question this assumption. The researchers set out to find out how people rate their subjective well-being in societies where money plays a minimal role, and which are not usually included in global happiness surveys. They found that the majority of people reported remarkably high levels of happiness. This was especially true in the communities with the lowest levels of monetization, where citizens reported a degree of happiness comparable to that found in Scandinavian countries which typically rate highest in the world. The results suggest that high levels of subjective well-being can be achieved with minimal monetization, challenging the perception that economic growth will automatically raise life satisfaction among low-income populations.

Measuring happiness

To explore how monetization affects people's sense of well-being, the researchers spent time in several small fishing communities, with varying degrees of monetization, in the Solomon Islands and Bangladesh, two very low-income countries. Over a period of a few months, with the help of local translators, they interviewed citizens in both rural and urban areas a number of times. The interviews, which took place both in person and through phone calls at unexpected moments, were designed to elicit information about what constituted happiness for the study subjects, as well as to get a sense of their passing moods, their lifestyle, fishing activities, household income, and level of market integration.

In all, the researchers interviewed 678 people, ranging in age between their mid-twenties and early fifties, with an average age of about 37. Almost 85 % of the study participants were male. The disproportionate number of men in the study was due to the fact that cultural norms in Bangladesh made it difficult to interview women. In the Solomon Islands, responses to the study questions from men and women were not significantly different. However, this is not necessarily applicable to the situation in Bangladesh, as men and women's social realities and lifestyles differ so much. Further research will need to address whether gender-related societal norms impact the association found in this study.

Early stages of monetization may be detrimental to happiness

The researchers found that in the communities where money was in greater use, such as in urban Bangladesh, residents reported lower levels of happiness.

"Our study hints at possible ways of achieving happiness that are unrelated to high incomes and material wealth," says Eric Galbraith, a professor in McGill's Department of Earth and Planetary Sciences and the senior author on the study, which was recently published in PLOS One. "This is important, because if we replicate these results elsewhere and can pinpoint the factors that contribute to subjective well-being, it may help us circumvent some of the environmental costs associated with achieving social well-being in the least developed nations."

"In less monetized sites, we found that people reported a greater proportion of time spent with family and contact with nature as being responsible for making them happy," explains Sara Miñarro, the lead author on the study who is a Postdoctoral Research Fellow at (ICTA-UAB). "But with increasing monetization, we found that the social and economic factors commonly recognized in industrialized countries played a bigger role. Overall, our findings suggest that monetization, especially in its early stages, may actually be detrimental to happiness."

Interestingly, while other research has found that technology and access to information from faraway cultures with different lifestyles may affect people's sense of their own well-being by offering standards to which people compare their own lives, this did not appear to be the case in these communities.

"This work adds to a growing realization that important supports for happiness are not in principle related to economic output," adds Chris Barrington-Leigh, a professor in McGill's Bieler School of the Environment. "When people are comfortable, safe, and free to enjoy life within a strong community, they are happy - regardless of whether or not they are making any money."

ITHACA, N.Y. - Soft robots may not be in touch with human feelings, but they are getting better at feeling human touch.

Cornell University researchers have created a low-cost method for soft, deformable robots to detect a range of physical interactions, from pats to punches to hugs, without relying on touch at all. Instead, a USB camera located inside the robot captures the shadow movements of hand gestures on the robot's skin and classifies them with machine-learning software.

The group's paper, "ShadowSense: Detecting Human Touch in a Social Robot Using Shadow Image Classification," published in the Proceedings of the Association for Computing Machinery on Interactive, Mobile, Wearable and Ubiquitous Technologies. The paper's lead author is doctoral student, Yuhan Hu.

The new ShadowSense technology is the latest project from the Human-Robot Collaboration and Companionship Lab, led by the paper's senior author, Guy Hoffman, associate professor in the Sibley School of Mechanical and Aerospace Engineering.

The technology originated as part of an effort to develop inflatable robots that could guide people to safety during emergency evacuations. Such a robot would need to be able to communicate with humans in extreme conditions and environments. Imagine a robot physically leading someone down a noisy, smoke-filled corridor by detecting the pressure of the person's hand.

Rather than installing a large number of contact sensors - which would add weight and complex wiring to the robot, and would be difficult to embed in a deforming skin - the team took a counterintuitive approach. In order to gauge touch, they looked to sight.

"By placing a camera inside the robot, we can infer how the person is touching it and what the person's intent is just by looking at the shadow images," Hu said. "We think there is interesting potential there, because there are lots of social robots that are not able to detect touch gestures."

The prototype robot consists of a soft inflatable bladder of nylon skin stretched around a cylindrical skeleton, roughly four feet in height, that is mounted on a mobile base. Under the robot's skin is a USB camera, which connects to a laptop. The researchers developed a neural-network-based algorithm that uses previously recorded training data to distinguish between six touch gestures - touching with a palm, punching, touching with two hands, hugging, pointing and not touching at all - with an accuracy of 87.5 to 96%, depending on the lighting.

The robot can be programmed to respond to certain touches and gestures, such as rolling away or issuing a message through a loudspeaker. And the robot's skin has the potential to be turned into an interactive screen.

By collecting enough data, a robot could be trained to recognize an even wider vocabulary of interactions, custom-tailored to fit the robot's task, Hu said.

The robot doesn't even have to be a robot. ShadowSense technology can be incorporated into other materials, such as balloons, turning them into touch-sensitive devices.

In addition to providing a simple solution to a complicated technical challenge, and making robots more user-friendly to boot, ShadowSense offers a comfort that is increasingly rare in these high-tech times: privacy.

"If the robot can only see you in the form of your shadow, it can detect what you're doing without taking high fidelity images of your appearance," Hu said. "That gives you a physical filter and protection, and provides psychological comfort."

URBANA, Ill. - From flooded spring fields to summer hailstorms and drought, farmers are well aware the weather is changing. It often means spring planting can't happen on time or has to happen twice to make up for catastrophic losses of young seedlings.

According to a joint study between University of Illinois and USDA-ARS, it also means common pre-emergence herbicides are less effective. With less weed control at the beginning of the season, farmers are forced to rely more heavily on post-emergence herbicides or risk yield loss.

"We're having more variable precipitation, including conditions where folks aren't able to plant because fields are too wet. In those cases, pre-emergence herbicide applications are getting pushed back into a period that is consistently drier," says Marty Williams, USDA-ARS ecologist, affiliate professor in the Department of Crop Sciences at Illinois, and corresponding author on the study.

Drier weather may be better for getting equipment onto the field for planting, but it's a problem for pre-emergence herbicides. Using data spanning 25 years and 252 unique weather environments, Williams and his team found most pre-emergence herbicides needed 5 to 15 centimeters of rain within 15 days of application. If that didn't happen, weed control rates plummeted.

"We already knew some rain after application was critical for the herbicide to move into the soil, but we didn't know how much or when," Williams says. "As we look to the future, having more variable rainfall and potentially increasing the frequency of falling below a critical rainfall threshold is problematic."

Christopher Landau, a doctoral candidate on the project, leveraged the university's long-running herbicide evaluation program, for which digital data are available across multiple Illinois locations from 1992 forward. He evaluated the effects of four common pre-emergence herbicides (atrazine, acetochlor, S-metolachlor, and mesotrione) alone and in combination, on three economically important weed species: common lambsquarters, giant foxtail, and waterhemp. He also extracted rainfall and soil temperature data.

The analyses clearly showed the overall need for rain after application, but the pre-emergence herbicides varied in their requirements for rainfall within that 15-day post-application window. For example, S-metolachlor required 10 to 15 centimeters of rainfall to maximize waterhemp control, whereas acetochlor only needed 5 centimeters to control the same weed.

Results also indicated herbicide combinations helped to minimize the amount of rainfall required for successful control. Continuing the example, when atrazine was added to S-metolachlor, the combination needed only 5 centimeters to achieve the same level of control.

"Herbicide combinations often provide additional benefits to weed control programs, including more consistent weed control. The continual evolution of herbicide resistance in species such as waterhemp requires more integrated control measures, and herbicide combinations can be one component of integrated systems designed to minimize weed seed production," says Aaron Hager, study co-author and associate professor and faculty Extension specialist in crop sciences at Illinois.

When the researchers considered the effect of soil temperature alone on herbicide efficacy, they didn't find a consistent pattern. But temperature was clearly important in low-rainfall scenarios.

"When rainfall was 10 centimeters or more within 15 days, the probability of successful weed control with most treatments was maximized under all soil temperatures. However, when rainfall was below 10 centimeters, higher soil temperatures either increased or decreased the probability of successful weed control, depending on the herbicide or herbicide combination. Ultimately, future temperatures in rainfall-limited conditions are likely to exacerbate variability in herbicide efficacy," Williams says.

The researchers note their findings may be especially important in the western Corn Belt, where erratic weather and low rainfall probabilities are even more common than in Illinois. But they still recommend the use of pre-emergence herbicides in combination, and urge farmers to be strategic in timing their application when rain is in the forecast.

"The development and adoption of more integrated weed management strategies that utilize pre-emergence herbicides, in combination with additional cultural, mechanical, biological, and postemergence chemical control options, are needed as U.S. corn production prepares to adapt to a changing climate," Landau says.