Thursday, February 09, 2023

In an astro-engineering approach to climate change mitigation, researchers calculate how dust could be fired from the Moon into space to attentuate the Sun's rays

PLOS

In an astro-engineering approach to climate change mitigation, researchers calculate how dust could be fired from the Moon into space to attentuate the Sun's rays.

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Article URL: https://journals.plos.org/climate/article?id=10.1371/journal.pclm.0000133

Article Title: Dust as a solar shield

Author Countries: USA

Funding: The University of Utah Office of Undergraduate Research provided a stipend to co-author SHK through the Undergraduate Research Opportunity Program (http://our.utah.edu/research-scholarship-opportunities/urop/). The funder(s) had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.

JOURNAL

PLOS Climate

DOI

10.1371/journal.pclm.0000133

ARTICLE TITLE

Dust as a solar shield

ARTICLE PUBLICATION DATE

8-Feb-2023

Could space dust help protect the earth from climate change?

Peer-Reviewed Publication

HARVARD-SMITHSONIAN CENTER FOR ASTROPHYSIC

Cambridge, Mass. – On a cold winter day, the warmth of the sun is welcome. Yet as humanity emits more greenhouse gases, the Earth's atmosphere traps more and more of the sun's energy, which steadily increases the Earth's temperature. One strategy for reversing this trend is to intercept a fraction of sunlight before it reaches our planet.

For decades, scientists have considered using screens or other objects to block just enough of the sun’s radiation — between 1 or 2 percent — to mitigate the effects of global warming. Now, a new study led by scientists at the Center for Astrophysics | Harvard & Smithsonian and the University of Utah explores the potential of using dust to shield sunlight.

The paper, published today in the journal PLOS Climate, describes different properties of dust particles, quantities of dust and the orbits that would be best suited for shading Earth. The team found that launching dust from Earth to a way station at the “Lagrange Point” between Earth and the sun would be most effective but would require an astronomical cost and effort.

The team proposes moondust as an alternative, arguing that lunar dust launched from the moon could be a low-cost and effective way to shade the Earth.

"It is amazing to contemplate how moon dust — which took over four billion years to generate — might help slow the rise in the Earth’s temperature, a problem that took us less than 300 years to produce,” says study co-author Scott Kenyon of the Center for Astrophysics.

The team of astronomers applied a technique used to study planet formation around distant stars — their usual research focus — to the lunar dust concept. Planet formation is a messy process that kicks up astronomical dust, which forms rings around host stars. These rings intercept light from the central star and re-radiate it in a way that can be detected.

“That was the seed of the idea; if we took a small amount of material and put it on a special orbit between the Earth and the sun and broke it up, we could block out a lot of sunlight with a little amount of mass,” says Ben Bromley, professor of physics and astronomy at the University of Utah and lead author for the study.

Casting a shadow

According to the team, a sunshield’s overall effectiveness would depend on its ability to sustain an orbit that casts a shadow on Earth. Sameer Khan, Utah undergraduate student and study co-author, led the initial exploration into which orbits could hold dust in position long enough to provide adequate shading.

“Because we know the positions and masses of the major celestial bodies in our solar system, we can simply use the laws of gravity to track the position of a simulated sunshield over time for several different orbits,” says Khan.

Two scenarios were promising. In the first scenario, the authors positioned a space station platform at the L1 Lagrange point, the closest point between Earth and the sun where the gravitational forces are balanced. Objects at Lagrange points tend to stay along a path between the two celestial bodies, which is why the James Webb Space Telescope (JWST) is located at L2, a Lagrange point on the opposite side of the Earth.

In computer simulations, the researchers shot particles from the platform to the L1 orbit, including the position of Earth, the sun, the moon, and other solar system planets, and tracked where the particles scattered. The authors found that when launched precisely, the dust would follow a path between Earth and the sun, effectively creating shade, at least for a while. The dust was easily blown off course by the solar winds, radiation, and gravity within the solar system. The team concludes that any L1 space station platform would need to create an endless supply of new dust batches to blast into orbit every few days after the initial spray dissipates.

“It was rather difficult to get the shield to stay at L1 long enough to cast a meaningful shadow. This shouldn’t come as a surprise, though, since L1 is an unstable equilibrium point,” Khan says. “Even the slightest deviation in the sunshield’s orbit can cause it to rapidly drift out of place, so our simulations had to be extremely precise.”

In the second scenario, the authors shot lunar dust from a platform on the surface of the moon towards the sun. They found that the inherent properties of lunar dust were just right to effectively work as a sunshield. The simulations tested how lunar dust scattered along various courses until they found excellent trajectories aimed toward L1 that served as an effective sunshield.

The results were welcome news, the team says, because much less energy is needed to launch dust from the moon than Earth. This is important because the amount of dust required for a solar shield is large, comparable to the output of a big mining operation here on Earth.

Kenyon says, “It is astounding that the Sun, Earth, and Moon are in just the right configuration to enable this kind of climate mitigation strategy.”

Just a moonshot?

The authors stress that their new study only explores the potential impact of this strategy, rather than evaluate whether these scenarios are logistically feasible.

“We aren’t experts in climate change, or the rocket science needed to move mass from one place to the other. We’re just exploring different kinds of dust on a variety of orbits to see how effective this approach might be. We do not want to miss a game changer for such a critical problem,” says Bromley.

One of the biggest logistical challenges — replenishing dust streams every few days — also has an advantage. The sun’s radiation naturally disperses the dust particles throughout the solar system, meaning the sunshield is temporary and particles do not fall onto Earth. The authors assure that their approach would not create a permanently cold, uninhabitable planet, as in the science fiction story, “Snowpiercer.”

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About the Center for Astrophysics | Harvard & Smithsonian

The Center for Astrophysics | Harvard & Smithsonian is a collaboration between Harvard and the Smithsonian designed to ask—and ultimately answer—humanity's greatest unresolved questions about the nature of the universe. The Center for Astrophysics is headquartered in Cambridge, MA, with research facilities across the U.S. and around the world.

JOURNAL

PLOS Climate

ARTICLE TITLE

Dust as a solar shield

ARTICLE PUBLICATION DATE

8-Feb-2023

Space dust as Earth’s sun shield

Dust launched from the moon’s surface or from a space station positioned between Earth and the sun could reduce enough solar radiation to mitigate the impacts of climate change.

Peer-Reviewed Publication

UNIVERSITY OF UTAH

On a cold winter day, the warmth of the sun is welcome. Yet as humanity emits more and more greenhouse gases, the Earth'satmosphere traps more and more of the sun's energy and steadily increases the Earth's temperature. One strategy for reversing this trend is to intercept a fraction of sunlight before it reaches our planet. For decades, scientists have considered using screens, objects or dust particles to block just enough of the sun’s radiation—between 1 or 2%—to mitigate the effects of global warming.

A University of Utah-led study explored the potential of using dust to shield sunlight. They analyzed different properties of dust particles, quantities of dust and the orbits that would be best suited for shading Earth. The authors found that launching dustfrom Earth to a way station at the “Lagrange Point” between Earth and the sun (L1) would be most effective but would require astronomical cost and effort. An alternative is to use moondust. The authors argue that launching lunar dust from the moon instead could be a cheap and effective way to shade the Earth.

The team of astronomers applied a technique used to study planet formation around distant stars, their usual research focus. Planet formation is a messy process that kicks up lots ofastronomical dust that can form rings around the host star. These rings intercept light from the central star and re-radiate it in a way that we can detect it on Earth. One way to discover stars that are forming new planets is to look for these dusty rings.

“That was the seed of the idea; if we took a small amount of material and put it on a special orbit between the Earth and the sun and broke it up, we could block out a lot of sunlight with a little amount of mass,” said Ben Bromley, professor of physics and astronomy and lead author of the study.

"It is amazing to contemplate how moon dust—which took over four billion years to generate—might help slow the rise in Earth’s temperature, a problem that took us less than 300 years to produce,” said Scott Kenyon, co-author of the study from the Center for Astrophysics | Harvard & Smithsonian.

The paper was published on Wednesday, Feb. 8, 2023, in the journal PLOS Climate.

Casting a shadow

A shield’s overall effectiveness depends on its ability to sustain an orbit that casts a shadow on Earth. Sameer Khan, undergraduate student and the study’s co-author, led the initial exploration into which orbits could hold dust in position long enough to provide adequate shading. Khan’s work demonstrated the difficulty of keeping dust where you need it to be.

Two scenarios were promising. In the first scenario, the authors positioned a space platform at the L1 Lagrange point, the closest point between Earth and the sun where the gravitational forces are balanced. Objects at Lagrange points tend to stay along a path between the two celestial bodies, which is why the James Webb Space Telescope (JWST) is located at L2, a Lagrange point on the opposite side of the Earth.

In computer simulations, the researchers shot test particles along the L1 orbit, including the position of Earth, the sun, the moon, and other solar system planets, and tracked where the particles scattered. The authors found that when launched precisely, the dust would follow a path between Earth and the sun, effectively creating shade, at least for a while. Unlike the 13,000-pound JWST, the dust was easily blown off course by the solar winds, radiation, and gravity within the solar system. Any L1 platform would need to create an endless supply of new dust batches to blast into orbit every few days after the initial spray dissipates.

“It was rather difficult to get the shield to stay at L1 long enough to cast a meaningful shadow. This shouldn’t come as a surprise, though, since L1 is an unstable equilibrium point. Even the slightest deviation in the sunshield’s orbit can cause it to rapidly drift out of place, so our simulations had to be extremely precise,” Khan said.

In the second scenario, the authors shot lunar dust from the surface of the moon towards the sun. They found that the inherent properties of lunar dust were just right to effectively work as a sun shield. The simulations tested how lunar dust scattered along various courses until they found excellent trajectories aimed toward L1 that served as an effective sun shield. These results are welcome news, because much less energy is needed to launch dust from the moon than from Earth. This is important because the amount of dust in a solar shield is large, comparable to the output of a big mining operation here on Earth. Furthermore, the discovery of the new sun-shielding trajectories means delivering the lunar dust to a separate platform at L1 may not be necessary.

Just a moonshot?

The authors stress that this study only explores the potential impact of this strategy, rather than evaluate whether these scenarios are logistically feasible.

One of the biggest logistical challenges—replenishing dust streams every few days—also has an advantage. Eventually, the sun’s radiation disperses the dust particles throughout the solar system; the sun shield is temporary and shield particles do not fall onto Earth. The authors assure that their approach would not create a permanently cold, uninhabitable planet, as in the science fiction story, “Snowpiercer.”

“Our strategy could be an option in addressing climate change,” said Bromley, “if what we need is more time.”

A simulation from dust launched from the way station at Lagrange point 1. The shadow cast on Earth is exaggerated for clarity.

A simulation of dust launched from the moon’s surface as seen from Earth.

CREDIT

Ben Bromley

JOURNAL

PLOS Climate

DOI

10.1371/journal.pclm.0000133

METHOD OF RESEARCH

Computational simulation/modeling

SUBJECT OF RESEARCH

Not applicable

ARTICLE TITLE

In an astro-engineering approach to climate change mitigation, researchers calculate how dust could be fired from the Moon into space to attentuate the Sun's rays

ARTICLE PUBLICATION DATE

8-Feb-2023

THE LANCET: No new COVID-19 variants have emerged during China's recent outbreak, analysis of cases in Beijing suggests

Peer-Reviewed Publication

THE LANCET

Peer-reviewed / Observational study / People

Genome analysis of 413 new COVID-19 infections in Beijing spanning the time period when China lifted its most strict pandemic control policies suggests all were caused by existing strains.

More than 90% of local infections in Beijing between November 14 and December 20, 2022,

involved Omicron sub-variants BA.5.2 or BF.7. Imported cases during the same period mostly involved different variants to those dominant in Beijing.

The authors say the findings can be considered a snapshot of the current state of the pandemic in China.

No new COVID-19 variants have emerged in China during the recent surge in infections since the country ended its zero-COVID policy, according to an analysis of cases in Beijing.

The study, published in The Lancet, suggests two existing Omicron sub-variants, BA.5.2 and BF.7 – among the most dominant variants in Beijing during 2022 – accounted for more than 90% of local infections between November 14 and December 20 2022.

The authors say the results represent a snapshot of the pandemic in China, due to the characteristics of Beijing’s population and the circulation of highly transmissible COVID-19 strains there.

China is widely reported to have ended its zero-Covid strategy on 7 December 2022. Since the lifting of these strict COVID-19 control policies – which included targeted lockdowns, mass testing and quarantine – surging case numbers have raised concerns that new variants could emerge. In the three years since COVID-19 was declared a global pandemic, the emergence of variants such as Alpha, Beta, Gamma, Delta, and Omicron has caused multiple waves of cases around the world.

Since December 2019, the study authors routinely collected respiratory samples from imported and local COVID-19 cases in Beijing, and randomly selected samples for analysis. There had been no persistent local transmissions reported in Beijing before December 2022.

In this latest study, the authors analysed COVID-19 samples detected in Beijing in 2022. Genome sequences were generated using rapid, large-scale sequencing technology, and their evolutionary history and population dynamics analysed using existing high quality COVID-19 sequences.

From a total of 2,881 high quality sequences included in the study, 413 new samples were randomly selected and sequenced between November 14 – when infections began to increase sharply – and December 20 2022. Of these, 350 were local cases and 63 were imported. Imported cases came from 63 countries and regions.

Analysis of the 413 new sequences revealed they all belong to existing, known COVID-19 strains. The dominant strain in Beijing after November 14 2022 was BF.7, which accounted for 75.7% of local infections. Another Omicron sub-variant, BA5.2, was responsible for 16.3% of local cases.

The populations of both BA5.2 and BF.7 in Beijing increased after November 14, 2022. The effective size of the BA.5.2 population did not change substantially between November 14 and 25, 2022, but increased sharply around November 30, 2022. The rise coincided with an increased number of BA.5.2 infections around November 30, 2022. The population of BF.7 increased gradually from November 14, 2022.

Lead author Professor George Gao, of the Institute of Microbiology at the Chinese Academy of Sciences, said: “Given the impact that variants have had on the course of the pandemic, it was important to investigate whether any new ones emerged following the recent changes to China’s COVID-19 prevention and control policies. Our analysis suggests two known Omicron sub-variants – rather than any new variants – have chiefly been responsible for the current surge in Beijing, and likely China as a whole. However, with ongoing large-scale circulation of COVID-19 in China, it is important we continue to monitor the situation closely so that any new variants that might emerge are found as early as possible.” [1]

The authors acknowledge some limitations to their study. While only data in Beijing in 2022, rather than the Chinese mainland, was analysed, the authors say the data is representative of the country as a whole. The number of laboratory-confirmed COVID-19 cases in December 2022 was unavailable because mandatory large-scale testing ended, suggesting the true number of infections is underestimated, leading to a degree of sampling bias in the dataset. More sampling is required to study the transmissibility and pathogenicity of Omicron sub-variants. The evolutionary rate of the virus was assumed to be constant during the initial stage of the outbreak, though it is possible this could vary depending on the variant.

Writing in a linked Comment, Professor Wolfgang Preiser and Dr Tongai Maponga of the University of Stellenbosch, South Africa, who were not involved in the study, said: “It is welcome to see this much-needed data from China. It is certainly reassuring that this study yielded no evidence for novel variants but not a surprise: the surge is amply explained by the abrupt cessation of effective control measures.” However, they urge caution in drawing conclusions about China as a whole based on data from Beijing, saying: “The SARS-CoV-2 molecular epidemiological profile in one region of a vast and densely populated country cannot be extrapolated to the entire country. In other regions of China other evolutionary dynamics might unfold, possibly including animal species that could become infected by human beings and “spill back” a further evolved virus.”

NOTES TO EDITORS

This study was funded by the National Key Research and Development Program of China and the Strategic Priority Research Program of the Chinese Academy of Sciences. It was conducted by researchers from the Beijing Center for Disease Prevention and Control, Chinese Academy of Sciences, Chinese Center for Disease Control and Prevention, and University of Chinese Academy of Sciences.

[1] Quote direct from author and cannot be found in the text of the Article.

The labels have been added to this press release as part of a project run by the Academy of Medical Sciences seeking to improve the communication of evidence. For more information, please see: http://www.sciencemediacentre.org/wp-content/uploads/2018/01/AMS-press-release-labelling-system-GUIDANCE.pdf if you have any questions or feedback, please contact The Lancet press office pressoffice@lancet.com

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JOURNAL

The Lancet

METHOD OF RESEARCH

Observational study

SUBJECT OF RESEARCH

People

ARTICLE TITLE

Characterisation of SARS-CoV-2 variants in Beijing during 2022: an epidemiological and phylogenetic analysis

ARTICLE PUBLICATION DATE

8-Feb-2023

Self-fulfilling prophecy: When physicians associate race and culture with poor health outcomes

Clinicians who attribute the prevalence of poor health outcomes among disadvantaged patients to race-based genetic and cultural differences are more likely to employ race-based care that reinforces disparities, investigators report in the American Journal

Peer-Reviewed Publication

ELSEVIER

Ann Arbor, February 9, 2023 – A novel study in the American Journal of Preventive Medicine, published by Elsevier, is the first to show a direct relationship between belief in race as a cultural phenomenon driving health disparities and the use of race in care. It found that family physicians at academic medical organizations who believe genetics and cultural attitudes are at the root of poor health outcomes of ethnic minority patients are likely to consider race when providing care.

“Disadvantaged and marginalized peoples are at greater risk of poor health outcomes than their White American counterparts. This reality has been used to justify the inclusion of race and ethnicity in medical recommendations, guidelines, and algorithms driving treatment thresholds and interventions – often without mention of the mechanisms through which these identities result in poor health. Using race without recognizing the social, political, and economic factors that contribute to racial inequity can stigmatize racially minoritized people as biologically inferior and normalize their poor health, worsening health disparities by codifying them as inevitable,” explained lead investigator Ebiere Okah, MD, MS, Department of Family Medicine and Community Health, University of Minnesota Medical School, Minneapolis, MN, USA.

The study cites the example of how until 2021 the vaginal birth after Cesarean (VBAC) calculator, which estimates the probability of a successful vaginal delivery after a Cesarean, used Black race and Hispanic ethnicity to predict an increased risk of failure, reducing the likelihood of these patients being offered a vaginal birth, a preferable birthing option. That changed in 2021 after more and more major medical societies began disavowing policies and practices that use race to ascertain disease risk.

Dr. Okah noted that physicians who believed social factors were responsible for racial differences in health were not more (or less) likely to use race to guide care. This implies that the belief that social factors contribute to racial inequity are not related to race-based practice.

The study is based on a cross-sectional national survey of 689 US academic family physicians conducted in 2021. It is the first to show a direct relationship between the belief that racially linked genetic and cultural factors drive health disparities and the employment of race-based care. The Racial Attributes in Critical Evaluation (RACE) scale was used to evaluate the degree to which race is used in clinical practices. High RACE scores were associated with the belief in genetic and cultural – but not socioeconomic -- causality.

According to the investigators, the question that remains unanswered is which specific clinician behaviors are related to viewing race as cultural. More needs to be known as to how clinicians differentially treat and counsel their patients based on racialized assumptions about their patients’ cultural values.

“The next step in this work is determining how to challenge the belief that race is related to cultural values. Part of the solution lies in advancing cultural humility as an alternative to cultural competency, acknowledging the cultural diversity that exists within racial groups, and considering the ways in which structural factors create what we perceive to be culture,” added Dr. Okah.

JOURNAL

American Journal of Preventive Medicine

DOI

10.1016/j.amepre.2022.10.019

METHOD OF RESEARCH

Survey

SUBJECT OF RESEARCH

People

ARTICLE TITLE

Race-Based Care and Beliefs Regarding the Etiology of Racial Differences in Health Outcomes

ARTICLE PUBLICATION DATE

9-Feb-2023

Endangered Bahamas bird may be lost from island following hurricane

Peer-Reviewed Publication

UNIVERSITY OF EAST ANGLIA

The endangered Bahama Warbler may be surviving on just one island following Hurricane Dorian’s devastation in 2019, according to researchers at the University of East Anglia.

A new study shows the bird’s distribution and ecology on Grand Bahama before the hurricane struck.

But the team says that the warbler may now only survive on neighbouring Abaco island, after hurricane Dorian destroyed the bird’s forest habitat on Grand Bahama.

The research comes from the same team that found what is thought to have been the last living Bahama Nuthatch, previously thought to have been extinct.

The fieldwork was conducted by two students on UEA’s Masters in Applied Ecology and Conservation, David Pereira and Matthew Gardner, who spent three months surveying the island for the Bahama Warbler and Bahama Nuthatch.

Their supervisor Prof Diana Bell, from UEA’s School of Biological Sciences, said: “Although more than half the endemic birds of the Bahamas are judged in danger of global extinction, there has been little international engagement to help remedy the situation.”

The Bahama Warbler is a little grey and yellow bird with a long bill and is only found on the islands of Grand Bahama and Abaco in the Bahamas.

But it is now classed as an endangered species - largely because its pine forest habitat has been seriously affected by urban development, human-induced fires, fly-tipping, logging and increased strength and frequency of hurricanes.

The team wanted to assess the birds’ conservation status and determine its habitat requirements after a Category 4 Hurricane (Matthew) hit the island in 2016. They also wanted to find out more about its habitat preferences for conservation purposes.

Pereira and Gardner searched for the little bird across 464 pine forest locations in Grand Bahama. They played recorded warbler song to attract the birds and also surveyed the habitat at each location, paying close attention to habitat damaged by hurricanes and fires.

They found a total of 327 warblers present in 209 of the 464 points surveyed. 71 per cent of sightings were in forests in the centre of the island and 29 per cent were in the East.

David Pereira said: “We found that the warblers were more likely to be present in sites with fewer needleless mature trees and some burnt vegetation. They seem to prefer living among taller, more mature, Thatch Palms. This is likely because these trees are capable of surviving forest fires and are also home to insects that warblers feed on.

“They also found that the species are quite adaptable, particularly when it comes to areas that have been affected by fire. This is probably because they can forage on tree trunks and use their bills to get under burnt peeling bark.”

Their co-supervisor Prof Nigel Collar, from BirdLife International, said: “We assume that Hurricane Matthew, which struck Grand Bahama only 18 months before our 2018 survey began, killed a significant proportion of the Bahama Warblers on the island. And it is possible that our findings on the bird’s preferences largely reflect the habitat that provided the best shelter.”

Fifteen months after the fieldwork ended, Hurricane Dorian devastated Grand Bahama with winds of 295 km per hour for over 24 hours, creating such human misery and economic damage that three years later the situation of the island’s wildlife remains unclear.

Matthew Gardner said: “It is possible that Grand Bahama’s entire population of Bahama Warblers was wiped out, but we know that the only other population of the species, on Abaco, has survived in the south of the island, where much of the forest remained standing.”

“We hope that our ecological insights will help conservation management on Abaco, but both islands now need to be surveyed,” added Prof Bell.

This research was funded by Thrigby Hall Wildlife Gardens and the Sir Philip Reckitt Educational Trust. The project was led by the University of East Anglia and BirdLife International in collaboration with the University of Chester.

‘Distribution and habitat requirements of the Bahama Warbler Setophaga flavescens on Grand Bahama in 2018’ is published in the journal Bird Conservation International.

ENDS

The endangered Bahama Warbler, which may be surviving on just one island following Hurricane Dorian’s devastation in 2019.

The endangered Bahama Warbler, which may be surviving on just one island following Hurricane Dorian’s devastation in 2019.

CREDIT

David Pereira

Searching for the endangered Bahama Warbler

CREDIT

Matthew Gardner

JOURNAL

Bird Conservation International

METHOD OF RESEARCH

Observational study

SUBJECT OF RESEARCH

Animals

ARTICLE TITLE

Distribution and habitat requirements of the Bahama Warbler Setophaga flavescens on Grand Bahama in 2018’

ARTICLE PUBLICATION DATE

9-Feb-2023

Breastfeeding may reduce arsenic exposure in infants in arsenic-contaminated areas

Texas A&M School of Public Health researchers use biomonitoring to measure how arsenic passes between mothers and their babies.

Peer-Reviewed Publication

TEXAS A&M UNIVERSITY

Arsenic contamination is a significant threat to human health in many parts of the world. Exposure to high levels of arsenic has been associated with a range of health problems such as diabetes, cognitive dysfunction, and certain types of cancer. In addition, arsenic exposure during pregnancy can cause miscarriages, reduced fetal growth and greater risk of health problems for children born in regions with high levels of arsenic. However, little is known about exactly how arsenic passes between mothers and their babies—both born and unborn—in populations living in contaminated areas.

A study published in the International Journal of Environmental Research and Public Health used biomonitoring techniques to gain insight into different possible routes of arsenic exposure in pregnant women and their children. Findings from the study show that arsenic can be passed through the placenta during pregnancy, and breastfeeding may reduce arsenic exposure in infants compared to formula feeding.

In this study, Taehyun Roh, PhD, assistant professor at the Texas A&M University School of Public Health, joined colleagues from several research institutions in Mexico to compare arsenic levels of people living in arsenic-contaminated areas of Mexico and a comparison population with lower levels of exposure.

Inorganic arsenic species, which are most commonly found in drinking water and crops grown using contaminated water, are known to cause oxidative stress and inflammation in humans, which can lead to a vast number of diseases over time. The health risks of arsenic exposure led the World Health Organization to set a safe maximum level of 10 micrograms per liter. In Comarca Lagunera, a region in northern Mexico, average arsenic levels in drinking water are 82 micrograms per liter, far exceeding the recommended maximum.

Roh and colleagues collected samples of drinking water, maternal blood, urine and breast milk along with samples of placenta and umbilical cord blood right after birth. They also collected neonatal urine samples immediately and three to four days after delivery. The researchers compared concentrations of arsenic in these samples against samples collected from populations living in areas with safe arsenic levels.

The researchers found significantly higher levels of arsenic in maternal blood and urine, umbilical cord blood, and breast milk in mothers living in Comarca Lagunera compared to uncontaminated regions. They also found that arsenic levels in cord blood were associated with levels in drinking water, and maternal urine samples from mothers and infants. These findings point to the placental passage as a major in utero transmission route for arsenic.

Infant urine samples collected days after birth showed continued high levels of arsenic, indicating a continuing source of arsenic contamination after birth. However, breast milk samples showed notably lower levels of arsenic than formula prepared with contaminated water.

This study found a clear association between maternal and neonatal arsenic exposure. The findings indicate transmission of arsenic through the placenta, which is consistent with existing research, and point to breastfeeding as a possible way to reduce arsenic exposure in infants compared to formula feeding. These findings highlight the importance of the further study of arsenic exposure and the need to develop interventions to reduce exposure in vulnerable groups.

JOURNAL

International Journal of Environmental Research and Public Health

DOI

10.3390/ijerph192316232

ARTICLE TITLE

Comparative biomonitoring of arsenic exposure in mothers and their neonates in Comarca Lagunera, Mexico

The ants go marching … methodically

Most biologists have assumed that ants wander aimlessly around a new environment. New University of Arizona research suggests that one species of rock ants actually searches in a more methodical way.

Peer-Reviewed Publication

UNIVERSITY OF ARIZONA

An ant belonging to the genus Temnothorax, a close relative to the ants used in this study. — IMAGE: THE ROCK ANTS STUDIED BY THE RESEARCHERS BELONG TO THE GENUS TEMNOTHORAX (PICTURED HERE IS A CLOSELY RELATED SPECIES). ROCK ANTS LIVE IN SMALL COLONIES AND OFTEN BUILD THEIR NESTS INSIDE ROCK CREVICES. view more
CREDIT: GILLES SAN MARTIN/WIKIMEDIA COMMONS

When strolling through an unfamiliar grocery store, you may find yourself methodically walking down each aisle to ensure you find everything you need without crossing the same path twice. At times, you'll stray from this orderly process, such as when you see a vibrant "for sale" sign from across the store or realize that you forgot something. According to a study led by researchers at the University of Arizona, some ants go about their search for food and shelter in a similar manner.

In a recent paper published in the journal iScience, UArizona researchers found that when a colony of rock ants is placed in an unfamiliar environment in the lab, the ants wander in a way that's not as random as previously thought. The ants followed a systematic meandering pattern combined with some random movement – a method with the potential to optimize exploration in their natural environment.

"Previously, researchers in the field assumed that ants move in a pure random walk when searching for targets of which they don't know their location," said Stefan Popp, the first author of the paper and graduate student in UArizona Department of Ecology and Evolutionary Biology. "We found that rock ants show a striking, regular meandering pattern when exploring the area around their nests."

In Arizona, these ants can be found nesting between or under rocks in areas above elevations of 7000 feet. These slow-moving critters are only about half the length of a medium grain of rice.

The study finds that the ants' meandering, or zigzag, walking pattern may make their search more efficient than a purely random search. This is because the ants can explore a large area in less time, as they cross their own paths less frequently.

"These ants don't form obvious foraging trails like many ants we are familiar with," Popp said. "Instead, the colony depends on individual foragers finding resources, making their search strategy a crucial part of colony success."

According to the researchers, the evolutionary advantage of meandering found in these rock ants could have possibly evolved in other species of insects and animals as well. The ants' movement could someday be used to inform the design of autonomous swarms of robots performing search and rescue missions in disaster areas or exploring landscapes on other worlds.

Because it is difficult to track ants in their natural environment, Popp and his team collected rock ant colonies from atop and around Mount Lemmon just north of Tucson. The team then moved the ants to the lab, placing them in an enclosed arena with a paper floor. The enclosure measured 2 by 3 meters – giant compared to the tiny scurrying ants.

After being introduced to a new home, the ants were eager to explore.

"These ants may have been patrolling the area for other competitor ants," Popp said, explaining that there is a selective pressure to keep other ants from intruding on their nest. "They may have also been searching for food and new nest sites."

The researchers soon noticed the meandering pattern of the ants as they walked around. It raised an immediate question: Were these patterns just random squiggles, or were the ants moving in a methodical, non-random way?

To address this question, the researchers set up cameras and used automatic-tracking software, coupled with manual corrections, to track the individual paths of each marching insect over the course of five hours. The ants' journeys were then compared to simulated ants walking in a random fashion.

"We looked at whether the direction in which an ant was moving in some way depended on the direction that it was moving before," said study co-author Anna Dornhaus, a professor in the UArizona Department of Ecology and Evolutionary Biology. "These methods helped us realize that the ants' search behavior was not completely random, as biologists had previously thought."

In other words, the researchers used statistics to determine that the direction an ant turned was directly correlated to the turns it had taken previously.

"Our research showed that the ants smoothly alternate left and right turns on a relatively regular length scale of roughly three body lengths," Popp said, "For some ants, the meandering-like search pattern was even more extreme than others, kind of like a meandering river in the Amazon basin. I am fascinated by this and wonder how the ants ensure that they don't cross their own path again and again, while still doing extreme turns and loops."

Popp and Dornhaus noted that they don't know how this search behavior changes across an ant's lifetime, or even if individual ants are aware of it. Regardless, the combination of meandering and randomness may be optimal for searching for resources in an unknown environment. The systematic approach can keep an ant close to its nest without crossing back and forth on previously explored ground. The added randomness accounts for obstacles that come with an unpredictable, natural environment.

"Until now, the widespread assumption was that free-searching animals are incapable of searching for new resources methodically," Popp said. "Most of the previous research on search behavior only focused on situations where the animal is already familiar with where it's going, such as going back to the nest entrance or going back to a memorable food source."

"Based on these results, many animals may be using complex combinations of random and systematic search that optimize efficiency and robustness in real and complex habitats," Dornhaus said. "This discovery opens up a whole new way of looking at all animal movement."

The researchers believe their discovery has the potential to unify different fields of science, including biology and robotics. The wanderings of these ants may have applications for real environments where a completely systematic search would fail when faced with an obstacle.

"This discovery could possibly lead to applications for roboticists as they program robots to be able to find their way around or search for something," Dornhaus said. "In this way, they can make their algorithms more robust, so they don't immediately fail as soon as the robot loses track of its exact location."

The researchers compared the walking paths of these ants to random simulations and discovered that these ants explored their newfound home with methodical movements, combined with some randomness.

This image shows all included ant tracks recorded during one 5-hour trial. The white circle indicates the position of the nest entrance. Zoom window shows a part of one track with an image of an ant to scale.

CREDIT

Dornhaus Lab/University of Arizona

JOURNAL

iScience

DOI

10.1016/j.isci.2022.105916

METHOD OF RESEARCH

Observational study

SUBJECT OF RESEARCH

Animals

ARTICLE TITLE

Ants combine systematic meandering and correlated random walks when searching for unknown resources

Trained dogs can sniff out a deadly deer disease

The proof-of-concept investigation by University of Pennsylvania researchers suggests detection dogs could be an asset in the effort to identify, contain, and manage chronic wasting disease, a highly contagious ailment

Peer-Reviewed Publication

UNIVERSITY OF PENNSYLVANIA

Charlie, Jari, and Kiwi are pet dogs with a superpower: Their sensitive noses can distinguish between a healthy deer and one sick with chronic wasting disease (CWD), all from a whiff of the deer’s poop.

That’s the finding of a study by scientists from Penn’s School of Veterinary Medicine, published in the journal Prion. Using feces samples from CWD-positive deer and deer in which CWD was not detected, the researchers trained the dogs to identify the odor of CWD, alerting their handlers to its presence in the lab and in the field.

“We were already quite certain that the dogs could detect the volatile organic compounds released by chronic wasting disease in feces,” says Amritha Mallikarjun, a postdoctoral researcher in Penn Vet’s Working Dog Center and lead author on the study. “Not only did we show this was possible, but we also answered a second, more interesting question, which is, Can they detect the disease in a simulated field setting, as they would if we were using the dogs to find the disease in the landscape of a forest or on a deer farm?”

The dogs indeed could, with enough accuracy to suggest that detection dogs could be a useful strategy in the fight to manage CWD.

“We learned a lot through the study and are now set up well to continue refining our training,” says Cynthia Otto, the senior author on the study and director of the Working Dog Center.

CWD is a disease that affects a variety of deer species, including white-tailed deer, mule deer, and elk. Always fatal and highly contagious, the disease can hide away in an affected animal for a year or two before symptoms manifest: the deer losing weight—“wasting”—and developing neurological signs, like stumbling and drooling. No cure or treatment exists.

The disease has been in Pennsylvania since 2012, and the state has invested significantly in trying to contain it, with several tools in place for keeping tabs on its spread. One hurdle is figuring out which deer are affected. A healthy-looking but infected animal could shed prions, malformed and infectious proteins, for many months or even years before succumbing to the illness. What’s more, prions are known to bind to soil, potentially contaminating the land on which other animals may roam.

The gold-standard diagnostic test can only be performed after death by assessing an affected animal’s brain. Some alternative tests have been trialed that involve taking a biopsy from a potentially infected animal while it’s still alive, but deer are known to be highly stressed by being captured, and collecting these samples can be physically and logistically difficult for the people involved as well.

The Working Dog Center, the Pennsylvania Department of Agriculture, and the Wildlife Futures Program, a partnership between Penn Vet and the Pennsylvania Game Commission, were well positioned to try to contribute an additional technique for managing the disease: dogs and their highly sensitive noses. Ideally, dogs trained to discern CWD-positive from CWD-not-detected feces in a forest or deer farm could help state agencies and private landowners understand whether further testing or management would be needed to keep their land and herds free from the disease.

First, scientists had to prove the dogs could make this distinction reliably. The Working Dog Center began by enlisting three dogs from their citizen science program—Labrador retrievers Charlie and Kiwi and Finnish spitz Jari—to train on the Center’s “scent wheel,” a contraption equipped with eight ports, each containing a specific substance or scent.

The dogs proved adept at this task. Once they had been trained, using samples provided by the U.S. Department of Agriculture and processed by the Wildlife Futures Program, the dogs responded with great specificity, passing by the not-detected samples 90-95% of the time. Their sensitivity, however, was not as strong, alerting to just 40% of the positive samples. Overall, the researchers found that the dogs spent more time at the ports containing positive samples than those with not-detected samples, suggesting that they perceived a difference even if they didn’t always produce the trained response, such as a bark or sitting down when they smelled the positive sample.

Moving toward a more naturalistic setting, the researchers then experimented with having the dogs and their handlers try to discern CWD-positive samples placed throughout a large, privately owned field. To avoid contaminating the soil or having the dogs come in contact with the samples, two-gram samples of feces were placed in jars with mesh lids to allow the odor to waft out and then partially buried in the ground in different areas.

The researchers observed that the dogs responded to the positive samples more often than the not-detect samples in the field trial. In total, they detected eight of 11 positive samples in the field, with a false negative rate of 13%. Both handlers and dogs seemed to improve as they went, their accuracy increasing after their first field search.

“Given the amount of time that we trained these dogs and the novel environment, not to mention the fact that these are pet dogs and not trained search dogs, our results are promising,” says Mallikarjun. “As we move forward and work with dogs that are specifically trained to search in a field setting and devote their entire lives to detecting this odor, they are going to do an even better job.”

That’s a step the Wildlife Futures Program is already taking, with canine handlers training “professional” detection dogs how to canvas fields and forests, searching for CWD.

The researchers believe that, while dogs don’t represent a silver bullet in the fight against CWD, they may prove useful as an early warning system, helping fill gaps in knowledge from other monitoring systems and management approaches.

“These dogs could increase the odds of catching an outbreak early,” says Lisa Murphy, a study co-author and co-director of the Wildlife Futures Program.

The Penn Vet team is also collaborating with other groups not only to work with detection dogs but also to identify the odor dogs may be responding to in order to develop other systems for early detection. The lessons learned could be broadly useful.

“If we’re able to tap into what we’ve learned with chronic wasting disease and apply it to other issues in agriculture and conservation, these dogs could be a major asset,” Otto says.

Amritha Mallikarjun is a postdoctoral fellow in the University of Pennsylvania School of Veterinary Medicine.

Lisa Murphy is resident director of PADLS New Bolton Center, a professor of toxicology, associate director of the Institute for Infectious and Zoonotic Diseases, and co-director of the Wildlife Futures Program at Penn’s School of Veterinary Medicine.

Cynthia Otto is a professor of working dog sciences and sports medicine and director of the Working Dog Center in Penn’s School of Veterinary Medicine.

Mallikarjun, Murphy, and Otto’s coauthors were Penn Vet’s Ben Swartz, Sarah A. Kane, Michelle Gibison, Isabella Wilson, Amanda Collins, Madison B. Moore, Ila Charendoff, and Julie Ellis and the U.S. Department of Agriculture’s Tracy Nichols. Mallikarjun is corresponding author on the study.

The work was supported by the Pennsylvania Department of Agriculture and the Wildlife Futures Program at the University of Pennsylvania School of Veterinary Medicine.

JOURNAL

Prion

DOI

10.1080/19336896.2023.2169519

METHOD OF RESEARCH

Experimental study

SUBJECT OF RESEARCH

Animals

ARTICLE TITLE

Canine detection of chronic wasting disease (CWD) in laboratory and field settings

ARTICLE PUBLICATION DATE

5-Feb-2023