It’s possible that I shall make an ass of myself. But in that case one can always get out of it with a little dialectic. I have, of course, so worded my proposition as to be right either way (K.Marx, Letter to F.Engels on the Indian Mutiny)
Tuesday, September 01, 2020
Aluminum recycling technology boosted by crystallization research
Under the influence of magnetic stirring, helical screw-like crystals form in molten alloy. Credit: Dr Biao Cai
An innovative method for aluminum recycling has been boosted by research showing the microscopic changes that take place when molten alloys cool.
Researcher Dr. Biao Cai from the University of Birmingham's School of Metallurgy and Materials used sophisticated high-speed X-ray imaging to record the formation of micro-crystals as alloys cool and solidify, under a magnetic field.
A mathematical model was developed by his collaborator Dr. Andrew Kao from the University of Greenwich to predict whether micro-crystals would form, and what shape they would have.
The model predicted that that helical 'screw-like' crystals would form under the influence of strong magnetic stirring, and the high-speed X-ray confirmed that this occurred.
Although these elegant crystals are just micro-meters wide (ten times smaller than a human hair), they have implications for industrial-scale processes.
Biao explains: "These microscopic crystals ultimately determine the physical properties of the alloy. To be able to adjust their shape, structure and direction of growth will enable us to perfect processes for both manufacturing and recycling of metals and alloys".
Biao has already invented technique to improve aluminum recycling by removing iron. Iron is a detrimental element that can make aluminum brittle, and limit its use in premium applications such as aircraft.
More information: B. Cai et al. Revealing the mechanisms by which magneto-hydrodynamics disrupts solidification microstructures, Acta Materialia (2020). DOI: 10.1016/j.actamat.2020.06.041
Workplace climate drives nurses' perception of burnout
(HealthDay)—Workplace climate is the factor most associated with burnout in nurses, according to a study published Sept. 1 in the American Journal of Critical Care.
Lakshmana Swamy, M.D., from the Boston Medical Center, and colleagues evaluated the frequency of burnout and individual and organizational characteristics associated with burnout among critical care nurses across a national integrated health care system using data from an annual survey. Analysis included responses to the 2017 survey from 2,352 critical care nurses from 94 sites.
The researchers found that one-third of nurses reported burnout, which varied significantly across sites. Workplace climate was the strongest predictor of burnout (odds ratio [OR], 2.20), but other significant variables included overall hospital quality (OR, 1.44), urban location (OR, 1.93), and nurse tenure (OR, 2.11). The workplace climate subthemes of perceptions of workload and staffing, supervisors and senior leadership, culture of teamwork, and patient experience were each significantly associated with burnout.
"Drivers of burnout are varied, yet interventions frequently target only the individual," the authors write.
A tagged loggerhead near the ocean surface after release. Credit: NOAA Northeast Fisheries Science Center
In early June 2011, NOAA Fisheries researchers and colleagues placed satellite tags on 26 loggerhead sea turtles in the Mid-Atlantic Bight. The tagging was part of ongoing studies of loggerhead movements and behavior. The Mid-Atlantic Bight, off the U.S. East Coast, is the coastal region from Cape Hatteras, North Carolina to southern Massachusetts. A little more than 2 months later, on August 28, Hurricane Irene passed through the area, putting 18 of the tagged turtles in its direct path. The researchers were able to track changes in the turtles' behavior coinciding with the hurricane, and found that they reacted in various ways.
"Hurricanes are some of the most intense weather events loggerheads in the mid-Atlantic experience, and we thought it was worth investigating how turtles in our dataset may be influenced by these dramatic environmental changes," said Leah Crowe, a contract field biologist at the NOAA Northeast Fisheries Science Center's laboratory in Woods Hole, Massachusetts, and lead author of the study published recently in Movement Ecology. "It was a perfect storm situation in terms of location, timing, and oceanographic conditions. We found that the turtles responded to the changes in their habitat in different ways."
Satellite tags attached to a turtle's carapace, or shell, transmitted the turtles' location and dive behavior. They also recorded sea-surface temperatures and temperature-depth profiles for approximately 13 months. This enabled the researchers to investigate the movements of 18 juvenile and adult-sized loggerhead turtles and associated oceanographic conditions as the hurricane moved through the region.
Most of the turtles moved northward during the hurricane, aligning themselves with the surface currents—perhaps to conserve energy. Researchers observed longer dive durations after the hurricane for turtles that stayed in their pre-storm foraging areas. Some dives lasted an hour or more, compared with less than 30 minutes for a typical dive before the storm.
The turtles that left their foraging areas after the hurricane passed moved south earlier than would be expected, based on their normal seasonal movements. This change was also more than a month earlier than the typical seasonal cooling in the water column, which is also when the foraging season for loggerhead turtles ends in the Mid-Atlantic Bight.
"Loggerheads experience environmental changes in the entire water column from the surface to the bottom, including during extreme weather events," said Crowe. "This study was an opportunistic look at turtle behavior during a hurricane. Their behavior makes loggerheads good observers of oceanographic conditions where they forage."
The study was conducted by researchers at the Northeast Fisheries Science Center and colleagues at the nearby Coonamessett Farm Foundation in East Falmouth, Massachusetts. The team has tagged more than 200 loggerheads in the Mid-Atlantic Bight since 2009.
This work has created a continuous time-series of data on loggerhead sea turtles. With 10 years of data, researchers can now get a deeper understanding of how turtles behave and what environmental factors drive them. They can also look back at the data and ask new questions, as they did in this study.
Waters in the Mid-Atlantic Bight are highly stratified, or layered, by temperature in the summer. At the surface, water is warm. A cold layer, also called a cold pool, forms beneath this warm layer and is present from May to October. The presence of the cold pool overlaps with the Atlantic hurricane season, which runs from June through November. It also overlaps with the presence of foraging loggerheads that are in the area between May and September.
Hurricane modeling is especially difficult in the Mid-Atlantic Bight because of the cold pool. In this study, it was unclear which aspect of the environmental changes prompted behavioral changes. Previous studies have found that loggerhead behavior appears to be sensitive to changes in water temperatures throughout the water column. Hurricanes cause the water layers to mix, which creates cooler surface temperatures. The mixing also disrupts the thermocline—the boundary layer between warm surface waters and colder, deeper waters.
Ocean temperature data recorded by the turtles' satellite tags are consistent with observations from weather buoys and autonomous gliders operating in the region. Depending on how many tags are deployed, data from tagged turtles can cover a more extensive area within a season than other oceanographic data sources.
More measurements of water temperatures throughout the water column in the region could help improve oceanographic models. Researchers say data from the turtle tags are an underused resource that has the potential to improve weather models, including hurricane models.
Many of the natural and human-induced impacts on sea turtle behavior, or the environments that sea turtles live in, are still unknown.
Previous studies indicate that sounds from dredge operations, seismic activity,offshore wind farm development, and marine recreation may also impact sea turtle distribution and dive behavior. Turtles might be impacted directly or through habitat alterations. While studies have looked at how tropical storms and hurricanes affect some marine species, there are few examples of examining sea turtle interactions with large storms.
In this study, turtle behavior did not return to pre-storm behavior within 2 weeks after the storm.
"The long-term cumulative effects of a changing climate and the increase in intensity of hurricanes and other storms is something that needs to be looked at. Changes in sea turtle movements and behavior can affect abundance estimates and management decisions," Crowe said. "This study reminds us that turtles live in a dynamic environment, and we cannot assume their behavior will be consistent throughout space and time."
More information: Leah M. Crowe et al, Riders on the storm: loggerhead sea turtles detect and respond to a major hurricane in the Northwest Atlantic Ocean, Movement Ecology (2020). DOI: 10.1186/s40462-020-00218-6
First-ever study of electronic waste shredding trucks shows the need for better safety guidelines.
A new Boston University School of Public Health study published in Annals of Work Exposure and Health is the first to evaluate the exposures faced by workers in mobile e-shredding, a new service to securely destroy hard drives, laptops, and other electronics containing confidential information on site.
Even proper electronic waste disposal still exposes workers to toxic metals such as lead and cadmium, as well as toxic chemicals—all of it usually ground into a fine powder that's easy to melt down for new gadgets, but also easy to inhale or even absorb through skin.
Dr. Diana Ceballos, assistant professor of environmental health at the Boston University School of Public Health (BUSPH), saw the growing use of mobile e-shredding trucks to destroy e-waste on site, including on university campuses, and was worried.
"I became particularly concerned with the almost non-existent safety measures, and potentially dangerous working conditions," Ceballos says.
She noticed workers not wearing masks or eye protection as they ground electronics to dust inside trucks that had no ventilation other than an open back door.
Ceballos and colleagues from the Harvard T.H. Chan School of Public Health evaluated the exposures during and after a 65-minute shredding job by one worker in a truck in the Greater Boston area.
Ceballos collected air samples (at the level of the worker's head) and surface wipes in different parts of the truck. The researchers found the concentrations of metal in the air near the shredder peaked at 2,500 ultrafine particles per cubic meter, including 2.9 micrograms of lead per cubic meter. "These exposures are similar to those experienced during a fire, or when using a diesel generator at a campsite," Ceballos says, "but the biggest challenge for the worker is that these levels are inside a truck and could accumulate to dangerous levels."
There were 171 micrograms of particulate matter 2.5 millimeters or less in diameter (known as PM2.5) per cubic meter. For comparison, the air in downtown Boston generally has 10-30 micrograms of PM2.5 per cubic meter, with notable and sometimes fatal effects.
After the job, the shredder and surfaces near it were coated with 1,190 micrograms of lead per square centimeter, and Ceballos found lead and other metals on surfaces as far away and separated from the shredder as the truck's cabin. Ceballos didn't take samples from the worker's clothes or skin, but notes that such contaminants can also come home with a worker and harm family members.
At least the generator powering the shredder in this truck was a new hybrid; with an older diesel generator and a differently configured truck, Ceballos says, a worker could be exposed to potentially fatal levels of carbon monoxide as well.
The verdict: Ceballos and colleagues found that the levels of metals and other contaminants in the truck were comparable to what they and other researchers have found in regulation-abiding, non-mobile e-recycling facilities. But workers in those facilities are supposed to wear protective equipment, and the facilities have exhaust ventilation (not just an open door) and regular cleaning.
(Ceballos says the trucks don't pose a risk to passersby out in the open air.)
"These trucks have become very popular and are a great service," Ceballos says. "My goal with this publication is to work with industry certifications to improve on their guidelines to strengthen the health and safety in these trucks."
But she says it isn't enough to just bring the trucks up to the same safety levels as non-mobile facilities.
E-recycling standards still aren't strict enough to fully protect the health of workers, in large part because the industry is so new, growing so quickly, and handling ever-changing technology, leaving government regulations in the dust.
The workers are also disproportionately "vulnerable," according to a new commentary in the American Journal of Industrial Medicine by Ceballos and colleagues at academic and government institutions including the Harvard Chan School, the University of Montreal, the National Institute for Occupational Safety and Health (NIOSH), and the Institut de recherche Robert-Sauvé en santé et en sécurité du travail (IRSST) in Quebec.
E-recycling workers, much like workers in many other high-risk and low-paying jobs, are much more likely to be members of racial/ethnic minorities, immigrants, under 25 years old, not fluent in English, and/or have physical or mental disabilities, the commentary authors write. Many are also currently or formerly incarcerated, including workers at nearly a dozen prison e-recycling sites in the US.
Ceballos says the e-recycling industry is one more example of how new hazards most affect groups who already face other health inequities. "Perhaps the public can understand this more clearly now during the pandemic," she says, "where the most vulnerable populations are those that have had the hardest time tackling the new virus.'Take-home' exposures are public health hazard
More information: Diana Ceballos et al, Metals and Particulates Exposure from a Mobile E-Waste Shredding Truck: A Pilot Study, Annals of Work Exposures and Health (2020). DOI: 10.1093/annweh/wxaa058
Many hospital workers infected with coronavirus don't show symptoms
by E.j. Mundell, Healthday Reporter
(HealthDay)—A new study of 13 U.S. medical centers finds that 6% of staff tested positive for prior infection with the new coronavirus, with almost half (44%) having no idea they'd ever contracted SARS-CoV-2.
In the study, blood antibody testing of more than 3,200 doctors, nurses and other hospital staff was conducted between early April and mid-June. About 1 in 16 of the tests came up positive, researchers found, and 29% of those positive results arose in people who said they'd had no symptoms suggestive of COVID-19.
Infection rates among staff also varied widely between hospitals, ranging from just 0.8% at one center to more than 31% at another. According to the study author, that likely reflects the level of coronavirus circulating in the city each hospital served.
One thing was clear, however: Use of masks, gowns, gloves and other protective gear by staff kept infection rates down. And when hospitals faced shortages of personal protective equipment (PPE), COVID-19 infections rose.
"A higher percentage of participants who reported a PPE shortage had detectable SARS-CoV-2 antibodies [9%] than did those who did not report a PPE shortage [6%]," reported researchers led by Dr. Wesley Self of Vanderbilt University Medical Center in Nashville, Tenn. About 12% of the workers interviewed in the study said they'd already encountered some form of PPE shortage at their medical center.
One emergency physician working on the frontlines of the pandemic agreed that prevention is key.
"Having an adequate supply of PPE is vital in order to mitigate the increased risk that all health care workers face on the frontlines," explained Dr. Robert Glatter, who practices at Lenox Hill Hospital in New York City.
"This represents one of the major ongoing challenges that has confronted hospitals and medical centers as the pandemic continues," he said.
Frequent testing of frontline health care workers is also crucial to curbing outbreaks early on because "a high proportion of personnel with antibodies did not suspect that they had been previously infected," Self's group said.
"What's important is that health care workers don't become a reservoir for asymptomatic spread of infection within the hospital setting or in the community," Glatter said. "As a result, we must invest in frequent testing of such vital workers."
The new study was published Aug. 31 in Morbidity and Mortality Weekly Report, a journal of the U.S. Centers for Disease Control and Prevention.
Study: Cancer cases likely in those exposed to atomic test
by Susan Montoya Bryan
Credit: CC0 Public Domain
After decades of study, the National Cancer Institute said Tuesday that some people probably got cancer from the radioactive fallout that wafted across New Mexico after the U.S. government detonated the first atomic bomb in 1945. However, the exact number is unknown.
The institute disclosed its conclusions in a series of scientific papers on radiation doses and cancer risks resulting from the Trinity Test, which marked a key point in the once-secret Manhattan Project. The Congress considers legislation that would include the downwinders in New Mexico in a federal compensation program for people exposed to radiation released during atmospheric tests or employees in the uranium industry.
"Too many of these unwilling participants in our country's national security strategy are still struggling with illness or have lost loved ones to radiation exposure," U.S. Rep. Ben Ray Lujan, a sponsor of the legislation, said after organizing a meeting in August with lawmakers, former miners, survivor groups from New Mexico, Idaho and Guam and others.
Downwinders have said their communities have been plagued by cancer, birth defects and stillbirths.
Tina Cordova, a co-founder of the Tularosa Basin Downwinders Consortium and a cancer survivor, has said the government did nothing at the time or in the decades after to monitor what was happening because of the fallout.
She has pointed to research published in 2019 in the Bulletin of the Atomic Scientists on data that showed a spike in infant mortality with no known cause other than it began after the Trinity Test. She said the increase followed what had been a steady decline in infant mortality in New Mexico up until August 1945.
The National Cancer Institute's research was aimed at trying to estimate the range of possible radiation-related cancer cases in New Mexico related to the Trinity Test. The team looked at published data on fallout from the test and gathered information about the typical diet and lifestyle of people living in the area in 1945.
Small focus groups were formed and interviews were done with 11 older adults who were in the same communities where they lived during the 1940s or 1950s.
The researchers described the process for estimating radiation doses as lengthy, saying the work involved more than 120 million calculations to estimate doses to the organs or tissues at greatest risk from fallout exposure. At the top of the list is the thyroid.
They estimated that the largest doses would have occurred in Torrance and Guadalupe counties based on the fallout pattern. All of the state's counties were included in the analysis.
While the full impact on New Mexico residents is difficult to gauge, officials with the institute say the models used and the review of possible paths for exposure—from inhaling dust contaminated by fallout to drinking water or milk and eating vegetables from the garden—make the Trinity study one of the most detailed assessments of exposure from nuclear testing fallout to have ever been conducted.
New research suggests that American mastodons were avid travelers, migrating vast distances across North America in response to dramatic climate change during the ice ages of the Pleistocene. The study, conducted by an international team of scientists and published today in the journal Nature Communications, also reveals that mastodon populations that headed northward to the Arctic during warm periods were less genetically diverse, making them vulnerable to extinction. The findings could be useful for modern conservation science.
"Today, you might think that it's great to see animals like brown bears in northern Canada and the Arctic islands, well beyond their historical range. They are obviously benefitting, just like these mastodons did for a time, as a result of natural climate change," said Ross MacPhee, a senior curator in the Museum's Department of Mammalogy and one of the authors on the study. "But that benefit can be very limited. It's important to realize that what we might think is beneficial change at one level for some species is not necessarily all that good for others."
Mastodons, which belong to a group closely related to modern-day elephants and extinct mammoths, were among the largest living land animals on Earth at the time, roaming from present-day Alaska and the Yukon east to Nova Scotia and south to Central Mexico. The species went extinct about 11,000 years ago along with other large mammals such as mammoths, sabre-toothed cats, and giant ground sloths.
Mastodon fossils discovered previously in northern climates indicate that the species likely had a large range, but scientists remained in the dark about when these migrations happened and whether mastodon populations took repeated trips or only went once. To find out more, the researchers reconstructed complete mitochondrial genomes from the fossilized teeth, tusks, and bones of 33 mastodons. The results show that the animals traveled extreme distances in response to warming climate conditions and melting ice sheets, from warmer environments to the northernmost parts of the continent.
"These mastodons were living in Alaska at a time when it was warm, as well as in Mexico and parts of Central America. These weren't stationary populations. The data show there was constant movement back and forth," said evolutionary geneticist Hendrik Poinar, director of the McMaster University Ancient DNA Centre and an author on the study.
The researchers suggest that examining how different ecologically adapted Pleistocene megafauna responded genetically and ecologically to such climate transitions can provide valuable information on how climate change is affecting modern-day species in the north.
"It's really interesting because a lot of species presently, like moose and beaver, are rapidly expanding their range northwards by as much as tens to hundreds of kilometers every century," said Emil Karpinksi, lead author on the study and a graduate student at the Ancient DNA Centre and the Department of Biology at McMaster University.
PlayNew research from an international team of scientists suggests that dramatic environmental changes accompanying the shift or melting of continental glaciers played a key role as American mastodons moved north from their southern ranges. Credit: McMaster University
The scientists also analyzed the genetics of the "pioneer" populations that made it to the north, finding that their genetic diversity was very low.
"That is always a danger signal for vertebrate species," said Grant Zazula, an author on the study and paleontologist with the Government of Yukon. "If you lose genetic diversity, you are losing ability to respond to new conditions. In this case, they were not up there long enough to adapt to northern conditions when they cycled back to cold."American mastodons made warm Arctic, subarctic temporary home 125,000 years ago
Although face shields block the initial forward motion of the jet, the expelled droplets move around the visor with relative ease and spread out over a large area depending on light ambient disturbances. Credit: Florida Atlantic University's College of Engineering and Computer Science
If the United States Centers for Disease Control and Prevention (CDC) guidelines aren't enough to convince you that face shields alone shouldn't be used to stop the spread of COVID-19, then maybe a new visualization study will.
To increase public awareness about the effectiveness of face shields alone as well as face masks with exhalation valves, researchers from Florida Atlantic University's College of Engineering and Computer Science used qualitative visualizations to test how face shields and masks with valves perform in impeding the spread of aerosol-sized droplets. Widespread public use of these alternatives to regular masks could potentially have an adverse effect on mitigation efforts.
For the study, just published in the journal Physics of Fluids, researchers employed flow visualization in a laboratory setting using a laser light sheet and a mixture of distilled water and glycerin to generate the synthetic fog that made up the content of a cough-jet. They visualized droplets expelled from a mannequin's mouth while simulating coughing and sneezing. By placing a plastic face shield and an N95-rated face mask with a valve, they were able to map out the paths of droplets and demonstrate how they performed.
Results of the study show that although face shields block the initial forward motion of the jet, the expelled droplets move around the visor with relative ease and spread out over a large area depending on light ambient disturbances. Visualizations for the face mask equipped with an exhalation port indicate that a large number of droplets pass through the exhale valve unfiltered, which significantly reduces its effectiveness as a means of source control.
PlayTo demonstrate the performance of the face shield, researchers used a horizontal laser sheet in addition to a vertical laser sheet revealing how the droplets cross the horizontal plane. Not only did the researchers observe forward spread of the droplets, they found that droplets also spread in the reverse direction. Credit: Florida Atlantic University's College of Engineering and Computer Science
"From this latest study, we were able to observe that face shields are able to block the initial forward motion of the exhaled jet, however, aerosolized droplets expelled with the jet are able to move around the visor with relative ease," said Manhar Dhanak, Ph.D., department chair, professor, and director of SeaTech, who co-authored the paper with Siddhartha Verma, Ph.D., lead author and an assistant professor; and John Frankenfeld, a technical professional, all within FAU's Department of Ocean and Mechanical Engineering. "Over time, these droplets can disperse over a wide area in both lateral and longitudinal directions, albeit with decreasing droplet concentration."
To demonstrate the performance of the face shield, researchers used a horizontal laser sheet in addition to a vertical laser sheet revealing how the droplets cross the horizontal plane. Not only did the researchers observe forward spread of the droplets, they found that droplets also spread in the reverse direction. Notably, face shields impede forward motion of the exhaled droplets to some extent, and masks with valves do so to an even lesser extent. However, once released into the environment, the aerosol-sized droplets get dispersed widely depending on light ambient disturbances.
Far-field view of a droplet spread when a face shield is used to impede the jet, 2.97 seconds after the initiation of the emulated cough. Credit: Siddhartha Verma, Manhar Dhanak, John Frankenfield
Like the N-95-rated face mask used in this study, other types of masks such as certain cloth-based masks that are available commercially also come equipped with one to two exhale ports, located on either side of the facemask. The N95-rated face mask with the exhale valve used in this study had a small amount of exhaled droplets that escaped from the gap between the top of the mask and the bridge of the nose. Moreover, the exhalation port significantly reduced the effectiveness of the mask as a means of source control, as a large number of droplets passed through the valve unfiltered and unhindered.
Researchers also tested an N-95 rated face mask with exhalation valves and found the exhalation port significantly reduced the effectiveness of the mask as a means of source control, as a large number of droplets passed through the valve unfiltered and unhindered. Credit: Florida Atlantic University's College of Engineering and Computer Science
"There is an increasing trend of people substituting regular cloth or surgical masks with clear plastic face shields as well as using masks that are equipped with exhalation valves," said Verma. "A driving factor for this increased adoption is better comfort compared to regular masks. However, face shields have noticeable gaps along the bottom and the sides, and masks with exhalation ports include a one-way valve which restricts airflow when breathing in, but allows free outflow of air. The inhaled air gets filtered through the mask material, but the exhaled breath passes through the valve unfiltered."
The researchers say that the key takeaway from this latest study illustrates that face shields and masks with exhale valves may not be as effective as regular face masks in restricting the spread of aerosolized droplets. Despite the increased comfort that these alternatives offer, they say it may be preferable to use well-constructed, high quality cloth or surgical masks that are of a plain design, instead of face shields and masks equipped with exhale valves. Widespread public adoption of the alternatives, in lieu of regular masks, could potentially have an adverse effect on ongoing mitigation efforts against COVID-19.
"The research conducted by professors Dhanak and Verma on the importance of proper face coverings to stop the spread of COVID-19 has literally illuminated the world," said Stella Batalama, Ph.D., dean of FAU's College of Engineering and Computer Science. "While broad acceptance regarding the need for face coverings has risen steadily, there is an increasing trend of people who are substituting regular cloth or surgical masks with clear plastic face shields, and with masks equipped with exhalation valves. This latest research provides important evidence to further support CDC guidelines and inform the public to make better selections in their choice for face coverings for their benefit and for public safety."
Iceberg in Antarctica: Temperature in the Southern Ocean was more tightly linked to the extent of the Antarctic glaciation during past greenhouse climates than previously thought. Credit: Alfred Wegener Institute, Thomas Ronge CC-BY 4.0
A new study published in Nature Geoscience shows that temperature in the Southern Ocean was more tightly linked to the extent of Antarctic glaciation during past greenhouse climates than previously thought. This affects how we see the complex mechanisms driving climate change around Antarctica, a region that is considered especially vulnerable to future changes.
Around 15 million years ago, in the Miocene, the Earth experienced high global temperatures and a greenhouse climate similar to that expected for the future. The warm period was followed by an abrupt transition towards cooler conditions and an expansion of the Antarctic ice sheet.
Although these changes went along with a drop in atmospheric CO2 concentrations, it was previously thought that the main reason for the ice sheet growth were changes in the Southern Ocean surrounding Antarctica. This is because previous data suggested a pronounced cooling in that ocean prior to the ice expansion, implying only an indirect role of CO2 for the ice sheet behavior.
"However, estimating ocean temperatures from the Miocene epoch, millions of years ago, is a major challenge," says Thomas Leutert, lead author of the new study.
Together, researchers with the Bjerknes Center of Climate Research and the University of Bergen and colleagues from the Max Planck Institute for Chemistry in Mainz, Germany, have applied not just one, but two independent methods for reconstructing temperatures in the upper waters of the Southern Ocean.
Two independent methods—The new results show that ocean temperature in the Southern Ocean cooled in lock-step with the expansion of the Antarctic ice sheet, challenging the previous notion that Southern Ocean surface waters cooled first and thereby triggered ice sheet growth on Antarctica, Thomas Leutert says.
The study is part of his doctoral thesis at the University of Bergen and the Bjerknes Center for Climate Research. Together with his supervisor Nele Meckler, Thomas Leutert studied the composition of tiny shells of microorganisms called foraminifera, found in the sediment cores collected from the Southern Ocean sea floor.
This tiny shell is a microfossil of a foraminifera called Globigerina bulloides, caught in a scanning electron microscope image. The small organism that produced the shell lived in the Southern Ocean millions of years ago. Analysis of the shell's isotopic composition tells of the ocean temperature when the organism was alive. Credit: Thomas Leutert, Image modified from Nature Geoscience
Based on the relatively new approach of "clumped isotope thermometry," analyses of isotopes in the microfossils tell of ocean temperatures during their lifetime.
In Germany, their colleagues at the Max Planck Institute for Chemistry applied another technique for reconstructing ocean temperatures, using the composition of molecules stemming from the soft tissues of a different kind of organism (Archaea).
The two techniques come with very different types of uncertainties and therefore do not necessarily yield consistent estimates of past ocean temperatures, even if applied at the same location. Consistent results, on the other hand, greatly increase confidence in the temperature reconstructions.
"And indeed, the results from both methods agree surprisingly well, and show a different picture than previous data," Thomas Leutert notes.
CO2 as a common factor
In the light of the results, the researchers argue that it becomes more likely that a common factor led to both ice growth and ocean cooling. This puts declining atmospheric CO2 levels back into focus: The decline in CO2 is likely to have led to both ocean cooling and ice sheet growth.
The new study provides a new perspective on the interactions between atmospheric CO2, Southern Ocean, and Antarctica across a dramatic transition in global climate. The findings of the study support the interpretation of a strong sensitivity of high-latitude climate to atmospheric CO2 changes, also in times long past.
More information: Thomas J. Leutert et al. Coupled Southern Ocean cooling and Antarctic ice sheet expansion during the middle Miocene, Nature Geoscience (2020). DOI: 10.1038/s41561-020-0623-0
1 in 20 older Americans smoke pot regularly, survey finds
by Dennis Thompson, Healthday Reporter
Credit: CC0 Public Domain
(HealthDay)—Marijuana use is on the rise among older Americans, with one in 20 saying they had used within the previous month, according to a new study.
About 5% of men and women aged 55 and older said they'd used marijuana or hashish in the previous month between 2016 and 2018, according to an annual federal government survey on potentially risky behaviors.
Use was twice as high among men, with about 6.7% reporting cannabis use during that three-year period compared to 3.5% of women.
There could be several explanations, an author of the new study said.
"It could be there are more people using marijuana for medical conditions. It could be there are more using it for recreational uses. It could be more people acknowledging use, in an environment when it's easier to say that you use products when talking to someone from the government," said co-researcher Bill Jesdale, an assistant professor at the University of Massachusetts Medical School, in Worcester.
Survey results found that reported cannabis use increased yearly between 2016 and 2018, rising from 4.2% of people 55 and older in 2016 to 5.9% in 2018.
Use among men rose from 5.5% in 2016 to 8.3% in 2018, while use among women went from 3.2% to 3.9%, the survey showed.
The largest increases occurred in the 11 states where recreational use of pot is legal, but pot use among seniors went up almost everywhere else as well, Jesdale said.
In all, 33 states have passed laws broadly legalizing marijuana in some form.
"Of course, we saw an increase in cannabis use in states where adult use is legal, and we saw an increase in states where medicinal use is legal, but we also saw an increase in states where there is no legal provision for use of cannabis," Jesdale said.
"Whether that's some sort of spillover effect as people see neighboring states loosening up and they start to feel more comfortable with it and interested in trying it out, it's hard to know," he added.
There are a number of concerns related to the increase in seniors using pot, said Pat Aussem, who reviewed the findings. She's associate vice president of consumer clinical content development at the Partnership to End Addiction in New York City.
"Aside from recreational use, older adults are using marijuana for pain relief, neuropathy, anxiety, depression, insomnia and a host of other medical conditions," she said. "The evidence supporting its use is sparse, as the marketing of it is way ahead of research with the exception of chronic pain, spasms related to multiple sclerosis, and nausea and vomiting resulting from chemotherapy."
One concern is that seniors who toked at Woodstock might not be ready for the increased potency of today's carefully cultivated marijuana, Aussem said.
Seniors also tend to take more medications than younger folks, increasing the risk that their pot might interact with their prescriptions in harmful ways, she added.
"There are hundreds of medications that interact with marijuana. For example, there is a concern that use of marijuana may increase the risk for bleeding in older adults on blood thinners," Aussem said. "There are only a handful of states that mandate pharmacist involvement in medical marijuana dispensing, so many older adults are on their own to figure out product selection, dosing, drug interactions and adverse effects."
These states highlight the need for more medical research on marijuana, to better inform seniors who are interested in trying pot either for fun or medicinally, she said.
"Seniors often seek guidance from their primary care doctors, but physicians are typically not equipped to guide patients with respect to choosing the right strain, dosing level and method of administration," Aussem said. "Even when speaking to a doctor to get a medical marijuana card, many seniors are surprised to learn that they may get a few recommendations, but not the prescription they are accustomed to getting."
The findings were published Sept. 1 in the Annals of Internal Medicine.
An ecological reconstruction of a 165-million-year-old lacewing mimicking a lichen that existed during the same time period. Credit: Xiaoran Zuo (CC BY 4.0)
Scientists have uncovered the earliest known evidence of an insect mimicking a lichen as a survival strategy, according to new findings published today in eLife.
The study suggests that the Jurassic moth lacewingLichenipolystoechotes mimicked the fossil lichen Daohugouthallus to help conceal itself from predators. This interaction predates modern lichen-insect associations by 165 million years, indicating that the lichen-insect mimicry (or 'mimesis') system was well established during the mid-Mesozoic period and provided lacewings with highly-honed survival strategies.
Animals sometimes mimic other organisms or use camouflage to deceive predators. Lichens, which consist of a fungus and alga living in close proximity, sometimes have a plant-like appearance and are occasionally mimicked by modern animals and insects. One of the most well-known cases of a lichen-insect association is when the peppered moth acquired a mutation that turned it black during the Industrial Revolution in Britain, allowing the moth to blend in with tree trunks and lichen darkened by soot.
"As lichen models are almost absent in the fossil record of mimesis, it is still unclear as to when and how the mimicry association between lichen and insect first arose," explains lead author Hui Fang, a Ph.D. student at the College of Life Sciences and Academy for Multidisciplinary Studies, Capital Normal University, Beijing, China. "The key to answer this question is to find early examples of a lichen-like insect and a co-occuring lichen fossil."
Fang and her team discovered deposits at the Daohugou 1 locality of Inner Mongolia in northeastern China that showed the 165-million-year-old lichen mimesis. The samples involved two lacewing species resembling a co-existing lichen from the latest Middle Jurassic.
After confirming the occurrence of the Jurassic lichen, the team then documented this mimetic relationship by describing structural similarities and detailed measurements of the lacewing and lichen. Their results suggest that when the lacewings rested in a lichen-rich habitat, a near-perfect match of their appearances would assist the insects' concealment from predators.
"Our findings indicate that a micro-ecosystem consisting of lichens and insects existed 165 million years ago in Northeastern China," concludes senior author Yongjie Wang, Associated Professor at the College of Life Sciences and Academy for Multidisciplinary Studies, Capital Normal University, Beijing. "This adds to our current understanding of the interactions between insects and their surroundings in the Mesozoic Era, and implies that there are many more interesting insect relationships awaiting discov
New Zealand startup eyes global wireless electrical grid
by Peter Grad , Tech Xplore
Credit: Unsplash/CC0 Public Domain
A startup energy company in New Zealand believes it can power the world with a wireless electric transmission system that can bring power to hard-to-reach areas and do so at lower cost than with traditional power lines.
The startup, Emrod, has teamed up with a leading power supply company to test power transmission using a series of antennas. The only limiting factor is the antennas must be within line of sight with each other.
The system consists of a power source, a transmitting antenna, multiple relay stations, and a receiving antenna, often referred to as a "rectenna."
Emrod converts electric energy into microwaves, which in turn are transmitted through a cylindrical beam to relay stations. Those stations refocus the beam and guide it along its path to the rectennas, where the microwaves are converted back to electricity.
The concept is not new. In fact, futurist, electrical engineer, and inventor Nikola Tesla envisioned a wireless electric system more than 100 years ago. Transcontinental microwave relay networks opened telephone communications between Europe and America in the 1950s, and recent decades have brought us increasingly efficient wireless network and satellite communication technologies.
What makes Emrod's system notable is its high degree of efficiency and near total absence of energy loss.
"The efficiency of all the components we've developed are pretty good, close to 100 percent," said Emrod founder Greg Kushnir. He said his system uses many of the same elements as the common household microwave oven, which achieves only a 70 percent efficiency. The development of newer materials for energy transmission in recent years helps to minimize energy loss, he said.
"We're not the first [to apply this technology], but we're the first ones to have a commercially viable solution," Kushnir said.
Emrod has tested the system over short distances, up to 130 feet so far. Company officials say there is no reason to believe the system will not work perfectly over hundreds miles. Offshore facilities could transmit power to hard-to-reach destinations. Power could be transmitted easily through mountainous regions or areas that would be too treacherous or too costly to lay traditional wiring through. Wireless power stations could be set up quickly in the aftermath of hurricanes or other natural disasters.
"We can use the exact same technology to transmit 100 times more power over much longer distances," Kushnir said. "Wireless systems using Emrod technology can transmit any amount of power current wired solutions transmit."
Could wildlife, such as birds, get zapped by the microwave beams? Emrod officials say a protective ring of laser beams acting as bodyguards around the microwave transmissions will shut off the beams when objects such as birds, other animals or humans, approach. The momentary outages should not affect overall power transmission. Facilities using sensitive equipment, such as medical devices, would need to have battery backups for the occasional power interruptions where stoppages of even just seconds could be critical.
Besides, the power density is low. "It's not just how much power you deliver, it's how much power you deliver per square meter," Kushnir said. "The levels of density we're using are relatively low. At the moment, it's about the equivalent of standing outside at noon in the sun, about 1 kW per square meter."
He says bad weather or adverse atmospheric conditions will have no impact on transmission. Should there be a failure in transmission, mobile stations attached to trucks could be dispatched relatively quickly.
"We have an abundance of clean hydro, solar, and wind energy available around the world but there are costly challenges that come with delivering that energy using traditional methods," Kushnir said. "I wanted to come up with a solution to move all that clean energy around from where it's abundant to where it's needed, in a cost-effective, eco-friendly way."
"Energy generation and storage methods have progressed tremendously over the last century but energy transmission has remained virtually unchanged" for 150 years, he said.
The joint project with Powerco will begin in October. The company also has plans to beam power across 19 miles of water from the New Zealand mainland to Stewart Island, at what is expected to be nearly half the cost of a traditional wired system.
The Warren mastodon, which was the first complete American mastodon skeleton found in the United States, on display in the Paul and Irma Milstein Hall of Advanced Mammals at the American Museum of Natural History. Credit: D. Finnin/ © AMNH
