Climate change could mean fewer sunny days for hot regions banking on solar power

by Morgan Kelly, Princeton University

Hot, arid regions may see greater fluctuations in sunlight as the climate changes, the researchers reported. They used satellite data and climate model outputs to evaluate the intermittency of solar radiation and the reliability of photovoltaic energy under future climate conditions. They found that arid areas (pink) were more likely to experience a decrease in average solar radiation -- and thus the reliability of solar power -- in January (top) and July (bottom). Credit: Jun Yin, Nanjing University of Information Science and Technology

While solar power is a leading form of renewable energy, new research suggests that changes to regional climates brought on by global warming could make areas currently considered ideal for solar power production less viable in the future.


Princeton-based researchers recently published in the journal Nature Communications the first study to assess the day-to-day reliability of solar energy under climate change. The team used satellite data and climate models to project how sunlight reaching the ground would be affected as warmer global temperatures alter the dynamics and consistency of Earth's atmosphere.

Their study found that higher surface temperatures—and the resulting increase in the amount of moisture, aerosols and particulates in the atmosphere—may result in an overall decrease in solar radiation and an uptick in the number of cloudy days. Hot, arid regions such as the Middle East and the American Southwest—considered among the highest potential producers of solar energy—were most susceptible to greater fluctuations in sunlight, the researchers found.

"Our results could help in designing better solar power plants and optimizing storage while also avoiding the expansion of solar power capacity in areas where sunlight intermittency under future climate conditions may be too high to make solar reliable," said corresponding author Amilcare Porporato, Princeton's Thomas J. Wu '94 Professor of Civil and Environmental Engineering and the Princeton Environmental Institute (PEI). The research was supported by the Carbon Mitigation Initiative based in PEI.

"To use an academic metaphor, in terms of solar power, semiarid places are now like students who get an A nearly every day," Porporato said. "Now, climate change is disturbing the usual dynamics of the atmosphere and the regularity of the solar radiation reaching the planet's surface. We tried to quantify how much more often those A's could become B's, or even C's, as a result."

Existing research on how solar energy will fare in this irregular future has largely focused on average levels of sunlight, said first author Jun Yin, a researcher at Nanjing University of Information Science and Technology who worked on the paper at Princeton as a postdoctoral research associate with Porporato.


"The novelty of our approach was to point out that in some places there is going to be more uncertainty in day-to-day variability," Yin said. He and Porporato previously reported that climate models underestimate the cooling effect of the daily cloud cycle. They worked on the most recent paper with co-author Annalisa Molini, an associate professor of civil infrastructure and environmental engineering at Khalifa University in the United Arab Emirates.

The researchers' findings were based on probabilistic calculations similar to those used to determine the risk of flooding or drought. The reduced reliability of solar energy is related to the increased variability of atmospheric moisture and aerosols in some arid regions. Higher temperatures hold more moisture and are more turbulent, which favors the formation of clouds and keeps particles in suspension longer, Porporato said.

"Then there is the issue of soils drying, which may be even more important," Porporato said. As temperatures and atmospheric turbulence increase in arid regions such as the Middle East, dry soils potentially lead to greater amounts of dust and atmospheric aerosols that would diminish solar radiation. These trends are in fact already detectable in observations from climate-observation networks, Porporato said.

For the American Southwest, the researchers' findings were less consistent. Some models showed more solar radiation and lower intermittency in the future, while others showed less solar radiation and higher intermittency. These results illustrate the challenge of trying to predict the reliability of solar energy in an uncertain future, Yin said.

"We hope that policymakers and people in the energy industry can take advantage of this information to more efficiently design and manage photovoltaic facilities," Yin said.

"Our paper helps identify efficient solutions for different locations where intermittency could occur, but at an acceptable level," he said. "A variety of technologies such as power storage, or power-operation policies such as smart curtailment, load shaping or geographical dispersion, are promising solutions."

To follow up on their work, the researchers plan to examine climate persistency—specifically, the number of consecutive sunny or cloudy days—which is important for solar power. They also are exploring how clouds could affect the effectiveness of tree planting as a climate mitigation strategy. Trees absorb not only carbon dioxide but also solar energy, which would raise surface temperatures. A resulting increase in cloud coverage could change current estimates of how effective trees would be in reducing atmospheric carbon.

The paper, "Impacts of solar intermittency on future photovoltaic reliability," was published Sept. 22 by Nature Communications.


Explore furtherClimate change impact on green energy production

More information: Jun Yin et al, Impacts of solar intermittency on future photovoltaic reliability, Nature Communications (2020). DOI: 10.1038/s41467-020-18602-6

Journal information: Nature Communications


Provided by Princeton University

Underwater robots to autonomously dock mid-mission to recharge and transfer data

by Jared Pike, Purdue University

A yellow underwater robot (left) finds its way to a mobile docking station to recharge and upload data before continuing a task. Credit: Purdue University photo/Jared Pike

Robots can be amazing tools for search-and-rescue missions and environmental studies, but eventually they must return to a base to recharge their batteries and upload their data. That can be a challenge if your robot is an autonomous underwater vehicle (AUV) exploring deep ocean waters.

Now, a Purdue University team has created a mobile docking system for AUVs, enabling them to perform longer tasks without the need for human intervention.

The team also has published papers on ways to adapt this docking system for AUVs that will explore extraterrestrial lakes, such as those of Jupiter and Saturn's moons.

"My research focuses on persistent operation of robots in challenging environments," said Nina Mahmoudian, an associate professor of mechanical engineering. "And there's no more challenging environment than underwater."

Once a marine robot submerges in water, it loses the ability to transmit and receive radio signals, including GPS data. Some may use acoustic communication, but this method can be difficult and unreliable, especially for long-range transmissions. Because of this, underwater robots currently have a limited range of operation.

"Typically these robots perform a pre-planned itinerary underwater," Mahmoudian said. "Then they come to the surface and send out a signal to be retrieved. Humans have to go out, retrieve the robot, get the data, recharge the battery and then send it back out. That's very expensive, and it limits the amount of time these robots can be performing their tasks."


Play VIDEO https://techxplore.com/news/2020-10-underwater-robots-autonomously-dock-mid-mission.html

A Purdue University team has created a mobile docking system for autonomous underwater vehicles, enabling them to perform longer tasks without the need for human intervention. Credit: Purdue University/Jared Pike

Mahmoudian's solution is to create a mobile docking station that underwater robots could return to on their own.

"And what if we had multiple docks, which were also mobile and autonomous?" she said. "The robots and the docks could coordinate with each other, so that they could recharge and upload their data, and then go back out to continue exploring, without the need for human intervention. We've developed the algorithms to maximize these trajectories, so we get the optimum use of these robots."

A paper on the mission planning system that Mahmoudian and her team developed has been published in IEEE Robotics and Automation Letters. The researchers validated the method by testing the system on a short mission in Lake Superior.


"What's key is that the docking station is portable," Mahmoudian said. "It can be deployed in a stationary location, but it can also be deployed on autonomous surface vehicles or even on other autonomous underwater vehicles. And it's designed to be platform-agnostic, so it can be utilized with any AUV. The hardware and software work hand-in-hand."

Mahmoudian points out that systems like this already exist in your living room. "An autonomous vacuum, like a Roomba, does its vacuum cleaning, and when it runs out of battery, it autonomously returns to its dock to get recharged," she said, "That's exactly what we are doing here, but the environment is much more challenging."

If her system can successfully function in a challenging underwater environment, then Mahmoudian sees even greater horizons for this technology.

"This system can be used anywhere," she said. "Robots on land, air or sea will be able to operate indefinitely. Search-and-rescue robots will be able to explore much wider areas. They will go into the Arctic and explore the effects of climate change. They will even go into space."


Explore further Blackout? Robots to the Rescue

More information: Bingxi Li et al, Collaborative Mission Planning for Long-Term Operation Considering Energy Limitations, IEEE Robotics and Automation Letters (2020). 

DOI: 10.1109/LRA.2020.3003881

Provided by Purdue University

This 'squidbot' jets around and takes pics of coral and fish

by University of California - San Diego


Engineers at the University of California San Diego have built a squid-like robot that can swim untethered, propelling itself by generating jets of water. The robot carries its own power source inside its body. It can also carry a sensor, such as a camera, for underwater exploration.

The researchers detail their work in a recent issue of Bioinspiration and Biomimetics.

"Essentially, we recreated all the key features that squids use for high-speed swimming," said Michael T. Tolley, one of the paper's senior authors and a professor in the Department of Mechanical and Aerospace Engineering at UC San Diego. "This is the first untethered robot that can generate jet pulses for rapid locomotion like the squid and can achieve these jet pulses by changing its body shape, which improves swimming efficiency."

This squid robot is made mostly from soft materials such as acrylic polymer, with a few rigid, 3-D printed and laser cut parts. Using soft robots in underwater exploration is important to protect fish and coral, which could be damaged by rigid robots. But soft robots tend to move slowly and have difficulty maneuvering.

The research team, which includes roboticists and experts in computer simulations as well as experimental fluid dynamics, turned to cephalopods as a good model to solve some of these issues. Squid, for example, can reach the fastest speeds of any aquatic invertebrates thanks to a jet propulsion mechanism.

VIDEO https://techxplore.com/news/2020-10-squidbot-jets-pics-coral-fish.html

Engineers at the University of California San Diego have built a squid-like robot that can swim untethered, propelling itself by generating jets of water. The robot carries its own power source inside its body. It can also carry a sensor, such as a camera, for underwater exploration. Credit: University of California San Diego

Their robot takes a volume of water into its body while storing elastic energy in its skin and flexible ribs. It then releases this energy by compressing its body and generates a jet of water to propel itself.

At rest, the squid robot is shaped roughly like a paper lantern, and has flexible ribs, which act like springs, along its sides. The ribs are connected to two circular plates at each end of the robot. One of them is connected to a nozzle that both takes in water and ejects it when the robot's body contracts. The other plate can carry a water-proof camera or a different type of sensor.

Engineers first tested the robot in a water testbed in the lab of Professor Geno Pawlak, in the UC San Diego Department of Mechanical and Aerospace Engineering. Then they took it out for a swim in one of the tanks at the UC San Diego Birch Aquarium at the Scripps Institution of Oceanography.


They demonstrated that the robot could steer by adjusting the direction of the nozzle. As with any underwater robot, waterproofing was a key concern for electrical components such as the battery and camera.They clocked the robot's speed at about 18 to 32 centimeters per second (roughly half a mile per hour), which is faster than most other soft robots.

"After we were able to optimize the design of the robot so that it would swim in a tank in the lab, it was especially exciting to see that the robot was able to successfully swim in a large aquarium among coral and fish, demonstrating its feasibility for real-world applications," said Caleb Christianson, who led the study as part of his Ph.D. work in Tolley's research group. He is now a senior medical devices engineering at San Diego-based Dexcom.

Researchers conducted several experiments to find the optimal size and shape for the nozzle that would propel the robot. This in turn helped them increase the robot's efficiency and its ability to maneuver and go faster. This was done mostly by simulating this kind of jet propulsion, work that was led by Professor Qiang Zhu and his team in the Department of Structural Engineering at UC San Diego. The team also learned more about how energy can be stored in the elastic component of the robot's body and skin, which is later released to generate a jet.


Explore further Transparent eel-like soft robot can swim silently underwater

More information: Caleb Michael Christianson et al, Cephalopod-inspired robot capable of cyclic jet propulsion through shape change, Bioinspiration & Biomimetics (2020). DOI: 10.1088/1748-3190/abbc72 

Journal information: Bioinspiration and Biomimetics


Provided by University of California - San Diego

Hacked hospital chain says all 250 US facilities affected

by Frank Bajak

In this March 14, 2014, file photo, a representative of GCHQ points to a screen showing all the teams progress in completing the task during a mock cyberattack scenario with teams of amateur computer experts taking part and trying to fight this simulated attack in London. Computer systems across a major hospital chain operating in the U.S. and Britain were down Monday, Sept. 28, 2020, due to what the company termed an unspecified technology "security issue." Universal Health Services Inc., which operates more than 400 hospitals and other clinical care facilities, said in a short statement p osted to its website Monday that its network was offline and doctors and nurses were resorting to "back-up processes" including paper records. (AP Photo/Alastair Grant, File)

The hospital chain Universal Health Services said Thursday that computer services at all 250 of its U.S. facilities were hobbled in last weekend's malware attack and efforts to restore hospital networks were continuing.

Doctors and nurses at affected hospitals and clinics, many already burdened with coronavirus care, have had to rely on manual record-keeping, with lab work slowed. Employees have described chaotic conditions impeding patient care.

The chain has not commented on reports it was hit by ransomware, though its description of the attack in a statement Thursday was consistent with malware variety that encrypts data into gibberish that can only be restored with software keys after ransoms are paid.

King of Prussia, Pennsylvania-based UHS said its "systems were quickly disconnected and the network was shut down in order to prevent further propagation."

The company, with 90,000 employees, said electronic medical records systems were not impacted by the attack and it was making steady progress restoring and reconnecting systems. Company spokeswoman Jane Crawford said via email that all 250 U.S. facilities were affected.

UHS workers reached by The Associated Press at company facilities in Texas and Washington, D.C., earlier in the week described mad scrambles after the outage began to render care, including longer emergency room waits and anxiety over determining which patients might be infected with the virus that causes COVID-19.

BleepingComputer, an online cybersecurity news site, spoke to UHS employees who described ransomware with the characteristics of Ryuk, which has been widely linked to Russian cybercriminals and used against large enterprises.

UHS operates hospitals and clinics, many treating behavioral health and addiction problem. Its acute care hospitals are concentrated in states including California, Texas, Nevada and Florida.

Explore further Cyberattack hobbles major hospital chain's US facilities

© 2020 The Associated Press. All rights reserved. This material may not be published, broadcast, rewritten or redistributed without permission.

Transportation barriers to care may increase likelihood of emergency surgical intervention

by American College of Surgeons


Transportation barriers, such as personal access to a vehicle or public transportation, disproportionally affect minority communities, according to results of a new study presented at the virtual American College of Surgeons (ACS) Clinical Congress 2020.


The study was performed by researchers at the University of Colorado at Aurora who used geographic information systems (GIS) to better understand traffic paths to hospitals offering elective and emergency surgical care throughout Denver. They tracked public transportation routes across census tracts and found areas with higher minority populations have nearly double the travel time burden to health care facilities when using public transportation.

Facilities with acute surgical capacity (emergency department, intensive care unit, and acute care surgery services) were identified within a 20-mile radius of the city center. Travel times were then estimated from the center of each census tract to the nearest facility by the shortest route. Using this method, the researchers determined travel times for individuals traveling by both car and public bus for a Monday morning appointment, weighted by percentage of the population in each census tract without vehicle access according to the American Community Survey.

For the 144 census tracts within Denver, the researchers found patients traveling by car were likely to spend approximately 12 minutes time driving to a health care facility as opposed to 33 minutes each way when traveling by public transportation. The overall drive times weighted by lack of vehicle access across the city are estimated to be 11 minutes by car and 28 minutes by bus. Additionally, census tracts with higher minority populations and higher populations without access to a personal vehicle saw approximately 3 minutes in increased travel time by bus for every 10 percent increase in the minority population.

Impact of Transportation Access on Medical Care

Barriers to health care access like race, income, and having insurance are well-documented, but structural barriers, like geography, can act in similar ways. In Denver specifically, freeway routes dividing the city and communities have shut residents off from resources to which they were previously able to walk. Prior work by the same group found that lack of health care coverage was not a significant barrier to surgical care where the majority of patients who presented emergently had some health care coverage, and many of the patients had sufficient coverage such that they had already been scheduled for elective surgical consultation, or even surgery itself.


Regardless of type of health care coverage, patients who presented emergently tended to live in areas of higher social vulnerability and were overwhelmingly non-white. Qualitative data derived from narrative data in the charts revealed that a common factor leading to emergent presentation included difficulties arranging transportation. In fact, approximately 3.6 million people in the United States forgo medical care due to transportation issues, such as lack of vehicle access, inadequate infrastructure, long distances, and lengthy travel times to reach services. As a result, procedures that could be treated in an outpatient appointment can frequently run the risk of becoming emergency situations.

Transportation patterns in areas where people don't have access to a vehicle can add 30 or more minutes to travel to an appointment. "When you factor in that people have to take additional time off from their jobs to go to an appointment to get elective care, and add in the fact that a lot of people have jobs where they don't have a lot of paid time off or the ability to take off that much time in a day, you may be looking at them having to take an entire day off to be able to make it to an elective surgical appointment. So, you're adding barrier after barrier, and these things tend to compound themselves," said study coinvestigator Catherine Velopulos, MD, MHS, FACS, a health services researcher and associate professor of surgery at the University of Colorado School of Medicine.

The findings also suggest a double effect of transportation barriers. Not only are some patients facing a greater barrier in terms of the percent of the population that has access to a private vehicle, but those same populations also have longer public transportation times per mile to acute care surgical facilities.

Using GIS to improve health care access

Census data can be used with GIS mapping to collect information about the environment, allowing local governments to identify communities with disproportionate transportation burden to acute care surgical services. By identifying where increased burden exists, cities can make structural changes to accommodate these needs.

"Place truly matters. Where you're located and where you live affects your health care outcomes," said coinvestigator Heather Carmichael, MD, a surgical resident at the University of Colorado School of Medicine. "If you can identify where patients are coming from, that gives you a lot of information about the environment that they're in that can affect their health care outcomes. And location of residence may be easier to determine in a research setting than in individually collecting each of those sociodemographic variables for an individual patient."

Understanding this combined data helps communities focus on where best to place resources like outreach programs and other forms of health care navigation, like Colorado's Non-Emergent Medical Transportation services, as well as to reevaluate traditional bus routes and pick up locations to better suit the needs of the community.

"A lot of people's access to the health care system is through surgical disease," added Dr. Velopulos, "And it's important for us as surgeons to recognize that we have a duty to improve access to care all around because it makes our patients healthier and our surgical outcomes better, and it allows us to reach our patients at an earlier point in their disease."

Explore further Cost, distance from hospitals present barriers to surgical care

More information: When More is Less: Increased Time Burden and Disparity in Access to Surgical Care by Transportation Means. Scientific Forum, American College of Surgeons Clinical Congress 2020, October 3-7, 2020.

Provided by American College of Surgeons

Black children more than twice as likely to die after surgical complications

by American Society of Anesthesiologists

Credit: Pixabay/CC0 Public Domain

When it comes to surgery, minority children lag far behind white children, according to two analyses of large national databases being presented at the ANESTHESIOLOGY 2020 annual meeting. One found Black children are more than twice as likely as white children to die following surgical complications that require an unplanned additional operation. Another study determined Black, Asian and Hispanic children are about half as likely to have surgery as white children.


"All parents want the best medical care for their children, and ensuring that quality surgical care is available for minority as well as white children will require a multifaceted solution," said Ethan L. Sanford, M.D., lead author of one of the studies and assistant professor of anesthesiology and pain management at UT Southwestern Medical Center, Dallas. "Clearly we have a lot of work to do."

Black children more likely to die after reoperation

Researchers at Nationwide Children's Hospital in Columbus, Ohio, set out to better assess a surgical outcome known as "failure to rescue" in Black children. In this context, failure to rescue means the patient suffered a post-surgical complication that led to a second unplanned operation, but ultimately died. While previous studies have looked at racial disparities related to this outcome in children having heart surgery, this study looked at failure to rescue in all surgeries.

The researchers analyzed data from the American College of Surgeons' National Surgical Quality Improvement Pediatric Participant Use Data file and found that of 276,917 children who had an inpatient surgical procedure between 2012 and 2017, 10,425 (8,409 white children and 2,016 Black children) suffered a complication that sent them back to the operating room. Two-hundred and nine children subsequently died, 135 white (1.6% of all white children who suffered a complication) and 74 Black (3.7% of all Black children who suffered a complication), meaning Black children were more than twice as likely to die.

They found the racial disparities in failure to rescue were greatest among the sickest children and when the reoperation occurred within four days of the initial surgery.

The researchers note there are many possible factors that lead to failure to rescue in Black children after surgery, including: socioeconomic status and access to quality care and preventive measures; and health risk factors, such as higher incidence of obesity, asthma and sleep apnea.


"We don't fully understand all of the issues that place a Black child at greater risk and how all of these issues interact with each other," said Brittany Willer, M.D., lead author of the study and a pediatric anesthesiologist at Nationwide Children's Hospital. "Our study gives physician anesthesiologists and surgeons insight into those at highest risk to heighten their awareness of the most vulnerable patients during the early post-operative period, which may have the biggest immediate impact on easing racial disparities."

Minority children less likely to have surgery than white children

Researchers at UT Southwestern Medical Center conducted the first study to assess the difference in the incidence of surgery between Black, Hispanic, Asian, and white children. They analyzed data from the National Health Interview Survey, which is conducted by the Centers for Disease Control and Prevention (CDC). The study included 227,025 children age 18 or younger, of whom 11,018 had received any type of inpatient or outpatient surgery within the previous 12 months.

Even after adjusting for factors, such as the health of the child, poverty, whether the child was insured and the level of education attained by the parents, minority children were about half as likely as white children to have surgery. The authors note there is no evidence to suggest that white children are more likely to need surgery or to have cosmetic procedures—factors that potentially could play a role in the large difference between the two groups.

"We must consider implicit systemic biases within perioperative health care," said Dr. Sanford. "Bias can occur at several points, from deciding whether to refer a child to a surgeon, when a surgeon is deciding whether or not to operate on a child and when a physician anesthesiologist is deciding whether it is safe for a child to proceed with surgery. Further, some minority families may mistrust the health system, there may be communication or cultural difficulties, as well as barriers such as travel and the ability to take time off work."

Dr. Sanford said he hopes the research will help lead to broader health disparities research, such as routine collection of race and ethnicity data for children during all health care visits. Also important are quality improvement initiatives such as standardized teaching for health care workers about systemic bias and cultural competency, as well as increasing workforce diversity.

ASA's Committee on Professional Diversity recently posted a "living" document, "Anesthesiology and Health Equity," which looks into health care disparities in resources, quality of care, outcomes and mortality based on race and socioeconomic status. The committee anticipates the document will be reviewed and updated as new insights and perspectives on the issue are brought to its attention.


Explore further 15-year trend persists in disparate insulin pump use in children

Provided by American Society of Anesthesiologists

CANADIAN STUDY

Mask mandates shown to significantly reduce spread of COVID-19

by Simon Fraser University

Credit: Pixabay/CC0 Public Domain

A new study by Simon Fraser University (SFU) researchers has found clear evidence that wearing a mask can have a significant impact on the spread of COVID-19. The researchers, from SFU's Department of Economics, have determined that mask mandates are associated with a 25 per cent or larger weekly reduction in COVID-19 cases.

The finding of their study, still in preprint and not yet peer-reviewed, conclude that mandating indoor masks nationwide in early July could have reduced the weekly number of new cases in Canada by 25 to 40 per cent in mid-August, which translates into 700 to 1,100 fewer cases per week.

The study analyzed the impact of mask mandates that were implemented across Ontario's 34 Public Health Units (PHUs) over the course of two months.

Researchers compared the results of PHUs that adopted mask mandates earlier to those that adopted mandates later. They determined that, in the first few weeks after their introduction, mask mandates were associated with an average weekly reduction of 25 to 31 per cent in newly diagnosed COVID-19 cases, relative to the trend in mask mandate absence, in July and August.

A further Canada-wide analysis with province-level data found a significantly negative association between mask mandates and subsequent COVID-19 case growth—up to a 46 percent average reduction in weekly cases in the first several weeks after adoption.

These results were supported by additional survey data that showed mask mandates increase self-reported mask usage in Canada by 30 percentage points, suggesting that the policy has a significant impact on behavior.

Jointly, these results suggest that mandating indoor mask wear in public places is a powerful policy measure to slow the spread of COVID-19, with little associated economic disruption in the short term.

The study also found that relaxed restrictions on businesses and gatherings (including retail, restaurants and bars) were positively associated with subsequent COVID-19 case growth—a factor that could offset and obscure the health benefits of mask mandates.

The most stringent restrictions on businesses and gatherings observed in the data were associated with a weekly decrease of 48 to 57 per cent in new cases, relative to the trend in the absence of restrictions.

The study authors note that while the results are significant, their sample period does not allow them to definitively say whether the effect of mask mandates persists or weakens beyond the first few weeks after implementation. However, they conclude that, combined with other policy measures, mask mandates can be a potent policy tool for slowing the spread of COVID-19.

Key Finding:
Mask mandates are associated with a 25 to 46 per cent average reduction in weekly COVID-19 cases across Canada.

Requiring indoor masks nationwide in early July could have reduced new COVID-19 cases in Canada by 25 to 40 per cent in mid-August, which translates into 700 to 1,100 fewer cases per week.

Mask mandates were shown to increase self-reported mask usage in Canada by 30 percentage points.

The most stringent restrictions on businesses and gatherings (including retail, restaurants and bars) were associated with a weekly decrease of 48 to 57 per cent in new cases, relative to the trend in the absence of restrictions.

Explore further  Follow the latest news on the coronavirus (COVID-19) outbreak

More information: Alexander Karaivanov et al, Face Masks, Public Policies and Slowing the Spread of COVID-19: Evidence from Canada, (2020).

DOI: 10.1101/2020.09.24.20201178

Provided by Simon Fraser University

Evidence of a cat recognizing and mimicking human behavior

by Bob Yirka , Phys.org

Credit: Animal Cognition (2020). DOI: 10.1007/s10071-020-01428-6

A small team of researchers with Eötvös Loránd University's Department of Ethology in Budapest has observed an instance of a house cat recognizing and then mimicking human behavior. The group has written a paper describing their observations and published it in the journal Animal Cognition.

Very few species have been observed imitating human behavior—only orcas, apes, elephants, dolphins and magpies—and now, that list has grown to include house cats. The finding comes as a surprise because cats were not thought to possess the necessary cognitive abilities to intentionally mimic the actions of other creatures.

The work was inspired in a roundabout way. Lead researcher Claudia Fugazza, an animal behaviorist, met with a colleague named Fumi Higaki who related that she had taught her pet cat to copy some of her behavior on command. Both Fugazza and Higaki had been studying an animal training technique called "Do as I do," whereby an animal is trained to perform an action, such as roll over, and then is taught to do it when the trainer speaks the words "do as I do." The training then progresses until an animal is shown a new behavior it has not performed before, and is asked to do it by the trainer once again speaking the worlds "do as I do." Fugazza and Higaki had both been studying the technique with dogs; thus, it was a surprise when Higaki related that she had used the technique to train her cat.

Higaki set up a demonstration of the cat in action at her pet store. To keep from spooking the cat, Fugazza sat some distance away from Higaki and her cat, which was named Ebisu. Fugazza observed as the cat responded to 18 requests to perform an action it had never done before following requests mimic Higaki, including opening a drawer, spinning around, reaching out and touching a toy, and laying down in a certain position. The cat was found to respond as desired approximately 81 percent of the time. The researchers suggest that the cat demonstrated the capability of mapping its own body parts to those of another creature, and to understand how those parts could be used in similar ways.


Explore further Your dog remembers what you did

More information: Claudia Fugazza et al. Did we find a copycat? Do as I Do in a domestic cat (Felis catus), Animal Cognition (2020). DOI: 10.1007/s10071-020-01428-6

Journal information: Animal Cognition


© 2020 Science X Network

A better understanding of how cirrus clouds form

by Steve Tally, Purdue University

New research from a team led by scientists at Purdue University has found that trees and plants play an important role in the formation of cirrus clouds, a finding that has implications for agriculture, urban development, and climate change modeling. 

Credit: J. Duclos via Unsplash.com

New research provides insights into how cirrus clouds form, with implications for agriculture, urban development and climate-change predictions. The study shows that trees and plants play an important role that affects precipitation and global climate change.

An international team combined theory, field measurements and lab experiments to develop a better understanding of the formation of clouds.

Daniel Cziczo, professor and head of Purdue University's Department of Earth, Atmospheric, and Planetary Sciences, said that, surprisingly, scientists didn't previously have a full understanding of how cirrus clouds form.

"These clouds have an effect on climate and precipitation—things we humans care deeply about," he said. "This paper tells us how particles in the atmosphere, whether from natural or human-made sources, can impact clouds in a way that we previously didn't understand."

Scientists knew that particles in the air from smoke and auto emissions would influence the creation of clouds, but this new research spotlights the importance of volatile emissions from plants and organic material, which the scientists call "secondary organic aerosols."

"This data will help us better predict how activities such as deforestation or reforestation will affect the world's climate, because these secondary organic aerosols are derived from plants," Cziczo said. "If the levels of these organic aerosols change, we'll now have a better understanding of what effects this will have and be able to use this information in global climate models."

Cziczo and the other authors of the paper were able to take data supplied by other researchers on the project and use it to create cirrus-like ice clouds in his Purdue laboratory, and then analyze the results using a specialized spectrometry instrument.

The research was published in Nature Communications.

"Everybody's heard of greenhouse gases and global warming, but I don't think many understand that clouds are a big player in climate change, too," Cziczo said. "The clouds also affect precipitation, which has an obviously large role in agriculture and human activities.

The cloud-formation mechanism described in the journal paper highlights the intricate interplay between human activities, the environment, and natural resources, such as rainfall.

"If our water resources change dramatically, that has huge consequences on our food production, land and resource utilization, things like that. So, we're really trying to understand both the water cycle and climate from the perspective of the atmosphere."

The science of clouds extends beyond what we see in the sky above us, Cziczo said, and the same chemistry and physics are at work in clouds on other planets.

"It does snow on Mars, and Mars has clouds. We've used some of our laboratory equipment that we use to understand clouds on Earth and adapted them to Martian conditions or conditions on Saturn's moon Titan using data from probes."

Explore further Thin tropical clouds cool the climate

More information: Martin J. Wolf et al. A biogenic secondary organic aerosol source of cirrus ice nucleating particles, Nature Communications (2020).

DOI: 10.1038/s41467-020-18424-6

Journal information: Nature Communications

Provided by Purdue University

Revising climate models with new aerosol field data

by Colorado State University

Instrumentation inlets and the view from the top of the tower at the Manitou Experimental Forest Observatory near Woodland Park, Colorado Credit: Delphine Farmer, CSU

Smoke from the many wildfires burning in the West have made air quality hazardous for millions of people in the United States. And it is the very tiniest of the aerosol particles in that air that make it particularly harmful to human health. But for decades, we haven't known how long these particles actually stay aloft.


New research by Colorado State University scientists is giving us a much better understanding of this process, which can help not only in air quality forecasting, but also in global climate modeling.

Aerosol particles, whether from wildfire smoke or car exhaust, play a large role in how much heat is absorbed or deflected by the atmosphere. However, we haven't entirely understood how quickly these tiny particles were pulled out of the air—especially in the absence of moisture. This has added substantial uncertainty to already-complex climate models.

Delphine Farmer, an associate professor in the Department of Chemistry in the CSU College of Natural Sciences, knew it was time we could do better.

Farmer and her colleagues recently announced that they have been able to detect, in real-world environments—from forests to grasslands—the rate at which these important particles actually leave the atmosphere. Their findings first appeared online the week of October 5 in the Proceedings of the National Academy of Sciences.

"This work really highlights the importance and power of field measurements," Farmer said. "We can directly use observations from field studies to narrow the uncertainties in climate models, and to improve our understanding of climate-relevant processes."

Zeroing in on uncertainty

Aerosol particles fall out of the air in two main ways. The first and most common is known as "wet" deposition, when moisture plucks them out of the air, whether through cloud formation, snow, or rainfall. Scientists have had a fairly good handle on this force, which accounts for some 80% of the aerosol effect in the atmosphere.

But the other force, "dry" deposition, has been much more mysterious, although it plays a not-insignificant role globally. Because aerosols are so small (measured in nanometers and microns) they don't simply come tumbling down due to gravity. They can waft along in currents of air for a long time. Just how long, however, has been the question.


"When a particle is emitted into the atmosphere, the amount of time it hangs out in the air depends on these removal processes," Farmer said. This is crucial, she explained, because "the longer a particle hangs out in the atmosphere, the more opportunity it has to travel farther, or make clouds, or impact human health. So getting the removal process right is essential for predicting particle concentrations—and their effects."

Early results from theoretical calculations in the 1970s and '80s, and cruder measurements completed over smooth surfaces around 2000, have been fed into climate models for decades.

This is where Farmer, who has made a research career tracking atmospheric chemistry with high-resolution instruments, saw an opportunity for improvement.

Improved climate models—and human health

Farmer and her colleagues knew that, of course, the land—and even ocean—surface isn't all smooth. So they wanted to see what was actually happening to these particles in the real world.

In particular, they looked at the forces beyond gravity that were driving these aerosols' journeys. "For the small, climate- and health-relevant particles, turbulence in the atmosphere brings particles down to surfaces and allows those particles to get stuck," Farmer said.

And because of this, these small particles don't have a straight path to a surface—especially in a complex surface environment like a forest. Farmer explained it as each microscopic aerosol particle running its own gauntlet, "kind of like American Ninja Warrior, where the particle has to avoid hitting different obstacles in order to stay in the atmosphere. And each gauntlet is particularly challenging for different sizes of particles."

To see how these variously sized particles were faring in this obstacle course, the researchers deployed an ultra-high sensitivity aerosol spectrometer, which uses a laser to count particles. They set up measuring stations in a pine forest in the Manitou Experimental Forest in Colorado, and in grasslands in the Southern Great Plains in Oklahoma, to capture real-world data on these particles as they eventually landed.

"We measured how fast different particles run this gauntlet," Farmer explained. "Then we used those measurements to figure out which part of the gauntlet slowed different particles down."

They found a much narrower range of lifetimes for these important particles than had been suggested by earlier modeling. In fact, the old predictions were counting on a faster removal of the very small particles (those less than 100 microns) and a slower removal of the larger particles (those greater than 400 microns).

"This means that we may have been underestimating the aerosol indirect effect in models," Farmer said. "The good news is that we have been overestimating the uncertainty—we now know particle loss rates better."

The new findings can be applied to all sorts of uneven surfaces, from forests to grasslands to agricultural areas even to choppy seas.

More aerosol effects over land

When integrating their findings into models of the aerosol effects globally, Farmer and her coauthors predict there will be more aerosol effect than previously assumed over certain land areas, including parts of North America, Europe, Asia, South America, Australia, and sub-Saharan Africa—and a lowering of the aerosol effect over oceans.

"It turns out that the particles' race to settle on a surface is pretty important for predicting radiative effects" and what the future climate might look like, Farmer said.

Their new data also suggests we've been underestimating the amount of the aerosols in the air that are most harmful to human health, those smaller than 2.5 nanometers (also known as PM2.5), which are, for example, the most commonly hazardous part of wildfire smoke.

"Our revised [number] increases surface PM2.5 concentrations by 11% globally and 6.5% over land," Farmer and her collaborators wrote in their new paper. Which is important to know because "exposure to PM2.5 is linked to respiratory and cardiovascular diseases."

Coauthors on the study included Jeffery Pierce, an associate professor in the Department of Atmospheric Sciences in the Walter Scott, Jr. College of Engineering, and Kelsey Bilsback, a postdoctoral researcher there; as well as doctoral researchers in the Department of Chemistry Ethan Emerson, Anna Hodshire, and Holly DeBolt; and Gavin McMeeking from the Handix Scientific company in Boulder.

This important work also demonstrates just how advanced—and impactful—field measurement technologies are becoming.

"To me, the most exciting aspect of this work is that we are able to take real-world measurements over a forest and a grassland site and use them to directly improve our understanding of the climate system," Farmer said.


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More information: Ethan W. Emerson et al, Revisiting particle dry deposition and its role in radiative effect estimates, Proceedings of the National Academy of Sciences (2020).

DOI: 10.1073/pnas.2014761117

Journal information: Proceedings of the National Academy of Sciences

Provided by Colorado State University