Extreme precipitation in northeast to increase 52% by the end of the century

A Dartmouth study projects more heavy rainfall events in the region due to climate change

Peer-Reviewed Publication

DARTMOUTH COLLEGE

 

IMAGE: EXTREME PRECIPITATION CHANGE BETWEEN 2070–2099 AND 1996–2005. view more 

CREDIT: FIGURE BY C.PICARD ET AL.

With a warmer climate creating more humid conditions in the Northeast, extreme precipitation events — defined as about 1.5 or more inches of heavy rainfall or melted snowfall in a day — are projected to increase in the Northeast by 52% by the end of the century, according to a new Dartmouth study.

The findings are published in Climatic Change.

"As climate change brings warmer temperatures, you have more water vapor in the atmosphere, which creates the right conditions for extreme precipitation," says first author Christopher J. Picard '23, an earth sciences major and undergraduate researcher in the Applied Hydroclimatology Group at Dartmouth.

"Our findings show that this increase in extreme precipitation will be primarily driven by more frequent heavy rainfall events, not by the intensity of such events," says Picard. "In other words, we expect a large increase in the number of extreme precipitation days, and a smaller increase in the amount of rain on each extreme precipitation day." 

The findings also show that winter and spring contribute most to the projected 52% increase in extreme precipitation in the region by 2070­ to 2099, with increases of 109% and 89%, respectively.

Through previous research, senior author Jonathan Winter, an associate professor of geography and lead of the Applied Hydroclimatology Group at Dartmouth, and other collaborators investigated how heavy rainfall events in the Northeast have changed historically. By examining data from 1901 to 2014, they found that there was about a 50% increase in extreme precipitation from 1996 to 2014, and that the increase was linked to climate change.

"Building on our earlier work, we were particularly interested in determining how much extreme precipitation is expected to change across the Northeast in the future," says Winter.

Similar to their other papers, the new study defines the Northeast as Maine, New Hampshire, Vermont, Massachusetts, Connecticut, Rhode Island, New Jersey, New York, Pennsylvania, Maryland, Delaware, West Virginia, and Washington, D.C.

Dartmouth's study found that extreme precipitation increases are projected to be largest in West Virginia, parts of Pennsylvania, central New York, and northeastern Maine, with predominantly smaller increases along the Atlantic coast and south of Lake Ontario.

The researchers applied a regional climate model from the National Center for Atmosphere Research to simulate precipitation for a historical period of 1996 to 2005 and future period of 2070 to 2099. Then, they compared their results to simulations of changing heavy rainfall events from other regional climate models, and found that their results are consistent with the other regional climate model simulations, which predict increases in extreme precipitation ranging from 58% to 169%.

"Extreme precipitation events can pose threats to life, property, infrastructure, and the environment," says Winter.

Previous research has reported how flooding, landslides, and erosion from these events can wash out roads, trigger agricultural runoff of pollutants, and damage recreational areas. "So, understanding where the flood plain is actually located, having the right sized culverts or green infrastructure in place, and properly designing roads and bridges, are important to managing the extra water that we're likely to encounter in the future," he says.

Winter is available for comment at: Jonathan.M.Winter@dartmouth.edu. Charlotte Cockburn, Guarini '21; Janel Hanrahan at Northern Vermont University — Lyndon; Natalie Teale, a postdoctoral fellow in geography with Dartmouth's Society of Fellows; and Patrick Clemins and Brian Beckage at the University of Vermont also contributed to the study. 

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JOURNAL

Climatic Change

DOI

10.1007/s10584-023-03545-w 

METHOD OF RESEARCH

Computational simulation/modeling

SUBJECT OF RESEARCH

Not applicable

ARTICLE TITLE

Twenty-first century increases in total and extreme precipitation across the Northeastern USA

ARTICLE PUBLICATION DATE

30-May-2023

Saved from extinction, Southern California’s Channel Island Foxes now face new threat to survival

Once threatened by disease and predators, foxes inhabiting six of Southern California’s Channel Islands were saved from extinction by the Endangered Species Act. Now, a new study shows they face a different threat: their own lack of genetic diversity.

Peer-Reviewed Publication

UNIVERSITY OF SOUTHERN CALIFORNIA

Island Fox - Channel Islands National Park (U.S. National Park Service) (nps.gov)

Tiny foxes — each no bigger than a five-pound housecat — inhabiting the Channel Islands off the coast of Southern California were saved from extinction in 2016. However, new research reveals that the foxes now face a different threat to their survival.

Suzanne Edmands, professor of biological sciences at USC Dornsife College of Letters, Arts and Sciences, and Nicole Adams, who earned her PhD from USC Dornsife in 2019, found that the foxes’ genetic diversity has decreased over time, possibly jeopardizing their survival and the biodiversity of the islands.

“The findings of this study highlight the alarming fact that the foxes currently inhabiting six of the Channel Islands possess extremely low genetic diversity, rendering them potentially more susceptible to dangers such as disease outbreaks and climate-induced environmental shifts,” Edmands said.

As the largest native land animals on the islands located 22 miles off the coast of Southern California, these bushy-tailed, big-eared creatures play a vital role in regulating plant and animal communities by consuming various food sources, including fruit, insects, snails, lizards, birds, and rodents. In fact, many plant species rely on them to distribute seeds through their scat.

“The importance of these animals to the overall biodiversity of the island can’t be over-emphasized. Without them, we could lose other species as well,” Edmands said.

A previous study done in 2018 lacked sufficient sampling to detect changes in genetic variation. This new study used a broader sampling method, comparing historic museum specimens and modern blood samples.

The bushy-tailed, big-eared Channel Island Foxes play a vital role in regulating plant and animal communities. (Photo: by Karl Huggins.)

Interestingly, the results indicated extremely low genetic variation even before the population declines. It also revealed that the genetic variation had dropped even further since population numbers fell. The islands that experienced the most severe losses, San Miguel and Santa Rosa, also showed the greatest reduction in genetic diversity. Santa Cruz and Santa Catalina, two islands where populations fell moderately, displayed mixed changes in genetic diversity metrics.

Placing these island foxes on the endangered species list from 2004-16 played a crucial role in population recovery. By 2017 — a year after they were removed as an endangered species —the population on Catalina was found to have increased over that 13-year period from approximately 100 to more than 2,000, while Santa Rosa Island’s fox population rose from a low of 15 to more than 1200 over the same time span. However, their depleted genetic diversity continues to hinder the foxes’ ability to adapt to future challenges, such as global warming and introduced diseases.

While genetic variation is crucial for disease resistance and adaptation to climate change, the scientists did find one silver lining in their research. They found reasonably good diversity within the foxes’ gut microbiome, a key player in bolstering immunity and overall well-being.

“This discovery suggests that the foxes may have developed an alternative mechanism to cope with changing environmental conditions,” Edmands said.

The study also reveals an increased divergence between the six islands over time. This finding complicates the possible conservation strategy of moving foxes between islands to increase genetic variation. Such a move could inadvertently disrupt local adaptation by producing offspring that are less fit or not as well adapted to their specific environments. It should be noted that each island population is recognized as a separate endemic or unique subspecies.

Given their limited ability to respond to new challenges, long-term monitoring of the fox population is crucial. To that end, researchers have already started non-invasive monitoring by sequencing bacterial communities in the foxes’ scat.

“The recovery of fox population numbers is an incredible conservation success, but their fragile genetic condition means that continued vigilance is critical to ensure their survival,” Edmands said.

About the Study

The research was funded by The Offield Family Foundation and USC Dornsife and was published in  Molecular Ecology.

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JOURNAL

Molecular Ecology

DOI

10.1111/mec.17025 

METHOD OF RESEARCH

Data/statistical analysis

SUBJECT OF RESEARCH

Animals

ARTICLE TITLE

Genomic recovery lags behind demographic recovery in bottlenecked populations of the Channel Island fox, Urocyon littoralis

Genetic change increased bird flu severity during U.S. spread

Scientists at St. Jude Children’s Research Hospital have discovered H5N1 avian influenza viruses gained the ability to cause severe disease and target the brain in mammals as they spread across North America.

Peer-Reviewed Publication

ST. JUDE CHILDREN'S RESEARCH HOSPITAL

 

IMAGE: H5N1 AVIAN INFLUENZA SPREAD FROM EUROPE TO NORTH AMERICA, THEN THROUGHOUT THE CONTINENT VIA WILD BIRDS. INSET SHOWS CLUSTERS OF INFECTIONS DETECTED ON THE EAST COAST FROM 2021-APRIL 2023, ACCORDING TO THE FOOD AND AGRICULTURE ORGANIZATION OF THE UNITED NATIONS. view more 

CREDIT: COURTESY OF ST. JUDE CHILDREN'S RESEARCH HOSPITAL

(MEMPHIS, Tenn. – May 29, 2023) St. Jude Children’s Research Hospital scientists discovered how the current epizootic H5N1 avian influenza virus (bird flu) gained new genes and greater virulence as it spread west. Researchers showed that the avian virus could severely infect the brains of mammalian research models, a notable departure from previous related strains of the virus. The researchers genetically traced the virus’ expansion across the continent and its establishment in wild waterfowl populations to understand what makes it so different. The study was recently published in Nature Communications.

 

“We haven’t seen a virus quite like this one,” said corresponding author Richard Webby, Ph.D., St. Jude Department of Infectious Diseases. “In 24 years of tracing this particular H5N1 flu lineage, we haven’t seen this ability to cause disease but also be maintained in these wild bird populations.”

 

When the scientists tested the newer avian flu strains for their ability to cause disease in mammals by infecting a ferret model, they found an unexpectedly high amount of pathogenicity.

 

“Some of these are really nasty viruses,” Webby said. “There’s a huge amount of the virus in the brain of infected animals. That’s the hallmark of what we saw with these flu strains — increased pathogenicity associated with high virus load in the brain. That’s not the first time we’ve seen H5 viruses in the brain, but these are probably some of the most virulent we’ve looked at over 24 years of following these viruses.”

 

Previous influenza viruses that caused severe disease in North America “burned out” in their main host bird population, and the outbreaks ended quickly. This current strain was detected at high levels in sick chickens but has expanded into other species.

 

“This is not just a chicken virus now,” Webby said. “It’s also infecting other avian and mammal species in the U.S. It’s a higher exposure risk for humans and other mammals than we’ve ever had in North America. We’ve never really been exposed to this level of circulation of these highly pathogenic flu viruses.”

 

A low risk to humans (for now)

 

While the newer strains of this H5N1 influenza show a greater ability to cause disease in mammals than earlier viruses, the scientists found it to be low-risk to humans. This is because the virus appears well-adapted to transmit between birds rather than between mammals.

 

“Overall, their risk to humans is still low,” Webby said. “But that risk does seem to be changing, and these viruses are doing things that we haven’t seen H5s do before. They’ve come into the continent’s wild bird population, they’ve reassorted, and they’ve been maintained over time. There are now many different types out there, and they're very nasty.”

 

Even though the risk of spreading infection is low, the research suggests humans should be cautious interacting with wildlife.

 

“Someone would have to work pretty hard to infect themselves with this virus. But if they do happen to be infected, there’s a real chance of getting a severe disease from it,” Webby said. “People just need to be careful and remember that some of the wild animals out there potentially harbor these highly pathogenic viruses.”

 

Genetic change supercharges spread and severity

 

In the past, similar strains of influenza viruses have not caused similarly severe diseases, nor have they become far-flung in wild bird populations. Since the new strains have done so much more damage, the scientists looked for what was different. The group identified the direct ancestor to the current strains, which spread from Europe to the Americas after gaining a different version of the viral protein, neuraminidase. This new protein increased the virus’s ability to transmit between birds. Then it arrived on the East Coast of Canada and traveled to the United States.

 

As the researchers studied the virus further, they pinpointed which viruses — distinct from previous ones —caused the current outbreaks. They found that after reaching North America, the virus rapidly changed again to become more virulent. It mixed with flu viruses in North American wild birds, swapping several genes. This reassortment of genes had two effects. One, the virus seemed to become even more adapted to the bird population, infecting many different types of birds. This included atypical hosts, such as buzzards and eagles, which typically do not get the flu. Second, the virus gained its severe disease-causing properties.

 

“The surprising thing was that just a few reassortment events did change these viruses’ ability to cause disease in our models,” Webby said. “And those events generated many different genotypes from that mixing. Then those viruses spread and have now become established in the North American wild bird population.”

 

Webby’s group and others continue to monitor the ongoing avian flu pandemic globally to assess its continually evolving risk to both humans and birds.

 

Authors and funding

The study’s co-first authors are Ahmed Kandeil, Christopher Patton, Jeremy Jones, Trushar Jeevan and Walter Harrington, all of St. Jude. The other authors are Sanja Trifkovic, Jon Seiler, Thomas Fabrizio, Karlie Woodard, Jasmine Turner, Jeri-Carol Crumpton, Lance Miller, Adam Rubrum, Jennifer DeBeauchamp, Charles Russell, Elena Govorkova, Peter Vogel and Lisa Kercher, St. Jude; Mia Kim-Torchetti, National Veterinary Services Laboratories, Animal and Plant Health Inspection Service (APHIS), US Department of Agriculture (USDA); Yohannes Berhane, National Centre for Foreign Animal Disease and the University of Manitoba and David Stallknecht and Rebecca Poulson, The University of Georgia.

 

The study was supported by grants and contracts from the National Institute of Allergy and Infectious Diseases (HHSN272201400006C, 7 5N93021C00016 and R01AI150745), the National Science Foundation (1911955) and ALSAC, the fundraising and awareness organization of St. Jude.

 

St. Jude Media Relations Contacts

 

Michael Sheffield
Desk: (901) 595-0221
Cell: (901) 379-6072
michael.sheffield@stjude.org
media@stjude.org

 

St. Jude Children's Research Hospital

St. Jude Children's Research Hospital is leading the way the world understands, treats and cures childhood cancer, sickle cell disease and other life-threatening disorders. It is the only National Cancer Institute-designated Comprehensive Cancer Center devoted solely to children. Treatments developed at St. Jude have helped push the overall childhood cancer survival rate from 20% to 80% since the hospital opened more than 60 years ago. St. Jude shares the breakthroughs it makes to help doctors and researchers at local hospitals and cancer centers around the world improve the quality of treatment and care for even more children. To learn more, visit stjude.org, read St. Jude Progress blog, and follow St. Jude on social media at @stjuderesearch. 

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JOURNAL

Nature Communications

METHOD OF RESEARCH

Experimental study

SUBJECT OF RESEARCH

Animals

ARTICLE TITLE

Rapid evolution of A(H5N1) influenza viruses after intercontinental spread to North America

ARTICLE PUBLICATION DATE

29-May-2023

Can phrases like ‘isn’t it?’ or ‘right?’ compromise classroom learning? New study answers

A researcher in Japan noted that the use of interrogative tags such as ‘isn’t it?’ and ‘right?’ by the teachers can limit student involvement and learning

Peer-Reviewed Publication

DOSHISHA UNIVERSITY

 

IMAGE: WHILE TEACHERS USE THE THIRD-TURN REPEAT STRATEGY TO ENCOURAGE STUDENT INCLUSION, IT MIGHT SILENCE CURIOSITY. view more 

CREDIT: MIKA ISHINO

Classroom education, in an ideal sense, must engage all students in a constructive discussion with the teacher, making it the latter’s responsibility to utilize different inclusive strategies. To bring the attention of distracted students back to the classroom discussion, teachers often have to use different methods to remind them that they are an equal and important part of this shared activity. This task can be tricky since most teachers attend to multiple students in a classroom. What strategies do teachers use to draw the attention of all the students to the common thread of a classroom discussion?

In a study that was recently published in Classroom Discourse, Dr. Mika Ishino of Doshisha University explored this question by analyzing the video recordings of classroom interactions between teachers and students in Japan. Dr. Ishino specifically examined how teachers employed the epistemic stance marker ‘ne’ during the classroom discussions, to make the interaction more inclusive with all the students. An epistemic stance marker is a word that modifies the tone of a sentence, to increase the interpersonal interaction between the speaker and the listener. “‘ne’ is roughly equivalent to English interrogative tags ‘you know’, ‘isn’t it’, and ‘right?’. It mainly marks the sharedness of the referent information between the speaker and the hearer,” explains Professor Ishino.

The study found that the epistemic stance marker ‘ne’ is commonly used in the third-turn during teacher-student interactions. In the first turn, the teacher asks a question to the class as a whole. In the second turn, one student usually answers the question. For the third-turn, the teacher then repeats the answer and adds ‘ne’ to open the interaction and include the rest of the students in this exchange.

“When the teachers produced their third-turn repeat in response to an individual student’s reply, they marked the repeated item with the Japanese epistemic stance marker, ‘ne’ or ‘na’, and shifted their gaze from the respondent individual to other students or ‘public space’ such as the blackboard”, Dr. Ishino observes. She further adds, “In doing so, the teachers treated the rest of the students as the party who also had access to the questioning item in the same manner as the respondent student.”

By using the third-turn repeat ‘ne’, teachers modify the nature of the interaction such that all students in the class, including the distracted, are given equal status in the discussion. Once this happens, the teacher moves on to the next question. However, Dr. Ishino found that this practice can have a negative impact on student involvement and learning. When the teachers use the third-turn repeat as a consistent strategy without checking if all the students are in sync, they potentially curtail the chance of any follow-up questions that the students can ask. “If there is a possibility that some students were not on the same page with the respondent student or did not know the answer to the questioning items, the inclusive third-turn repeat is designed to limit the students’ responses to a silent agreement,” Dr. Ishino concludes.

The study reveals that in an interaction with multiple students, it is crucial for teachers to ensure that no student is more privileged than others. Furthermore, the use of third-term repeats like ‘ne’ may be a helpful way to encourage inclusive learnings during classroom discussions. However, it can have serious negative consequences on student involvement and learning in the long term.

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About Dr. Mika Ishino from Doshisha University, Japan
Dr. Mika Ishino is an associate professor in the Faculty of Global and Regional Studies, Department of Global and Regional Studies at Doshisha University. Her academic interests include applied linguistics, language teacher education, and conversation analysis. She has previously worked at public high schools in Japan as an English teacher. Her research interest mainly lies in how teachers accomplish the pedagogical goals in their classroom institutional settings. She has also been the recipient of the ‘Best Paper Award’ by the Japan Society of Educational Sociology.

Funding information
The Japan Society supported this work for the Promotion of Science under Grant number: 19K13305.

Media contact:
Organization for Research Initiatives & Development
Doshisha University
Kyotanabe, Kyoto 610-0394, JAPAN
E-mail：jt-ura@mail.doshisha.ac.jp

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JOURNAL

Classroom Discourse

DOI

10.1080/19463014.2023.2190033 

METHOD OF RESEARCH

Observational study

SUBJECT OF RESEARCH

People

ARTICLE TITLE

Inclusive Third-Turn Repeats: Managing or Constraining Students’ Epistemic Status?

ARTICLE PUBLICATION DATE

29-May-2023

WAIT, WHAT?!

Reduced emissions during the pandemic led to increased climate warming

Peer-Reviewed Publication

STOCKHOLM UNIVERSITY

 

IMAGE: ÖRJAN GUSTAFSSON IN THE TOWER AT HANIMAADHOO MEASURING STATION. view more 

CREDIT: PHOTO: JOAKIM ROMSON

The Covid pandemic shutdowns in South Asia greatly reduced the concentration of short-lived cooling particles in the air, while the concentration of long-lived greenhouse gases was barely affected. Researchers were thus able to see how reduced emissions of air pollution leads to cleaner air but also stronger climate warming.

It is well known that emissions of sulfur and nitrogen oxides and other air pollutants lead to the formation of aerosols (particles) in the air that can offset, or mask, the full climate warming caused by greenhouse gases such as carbon dioxide and methane. But there has been a lack of knowledge about this ‘masking effect’. In order to determine the size, large-scale experiments involving huge regions would be required – this is infeasible.

The Covid pandemic became such a ‘natural’ experiment. In the spring of 2020, the activity of many industries and transportation worldwide decreased due to pandemic restrictions. This created a unique opportunity to study what happens to the climate if emissions of gases and aerosols are rapidly reduced.

Measuring station in the northernmost Maldives
At Hanimaadhoo, a measuring station in the northernmost Maldives off the coast of India, researchers have been measuring  the atmospheric composition and radiation for soon two decades. (Measurements reveal the impact of air pollution on climate and health in southern Asia) The measuring station is strategically placed to capture air masses from the Asian subcontinent and located in an area with few regional emission sources. When emissions suddenly decreased during the pandemic in South Asia (mainly Pakistan, India and Bangladesh), an opportunity was created to see what impact this had on the climate.

Short-lived air particles decreased but not greenhouse gases
A new article in the scientific journal NPJ Climate and Atmospheric Science shows that the concentrations of polluting short-lived air particles decreased significantly, while the concentrations of longer-lived greenhouse gases were barely affected in the air mass over South Asia. The cooling effect of the aerosols comes from the fact that they reflect incoming solar radiation back into space. With a lower aerosol content, there is less cooling, and thus less ‘masking’ of the warming effect of the significantly longer-lived climate gases. Measurements taken at the same time over the northern Indian Ocean revealed a seven percent increase in solar radiation reaching the Earth’s surface, thus increasing temperatures.

“Through this large-scale geophysical experiment, we were able to demonstrate that while the sky became bluer and the air cleaner, climate warming increased when these cooling air particles were removed,” says Professor Örjan Gustafsson at Stockholm University, who is responsible for the measurements in the Maldives and who led the study.

The results show that a complete phasing out of fossil fuel combustion in favor of renewable energy sources with zero emissions could result in rapid ‘unmasking’ of aerosols, while greenhouse gases linger.

“During a couple of decades, emission reductions risk leading to net climate warming due to the ‘masking’ effect of air particles, before the temperature reduction from reduced greenhouse gas emissions takes over. But despite an initial climate warming effect, we obviously still urgently need a powerful emission reduction,” says Örjan Gustafsson.

Hanimaadhoo measuring station in the northernmost Maldives.

CREDIT

Photo: Joakim Romson

Contact:
Örjan Gustafsson, professor of biogeochemistry at Stockholm University
E-mail: orjan.gustafsson@aces.su.se Phone: 0046703247317

Read article in NPJ Climate and Atmospheric Science.

Additional reading: Measurements reveal the impact of air pollution on climate and health in southern Asia

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JOURNAL

npj Climate and Atmospheric Science

ARTICLE TITLE

Aerosol demasking enhances climate warming over South Asia

1 in 5 teachers feel carrying gun to class would make schools safer; More than half think armed teachers would make students less safe

Reports and Proceedings

RAND CORPORATION

U.S. teachers are divided on whether arming themselves would make schools safer, with one in five saying they would be interested in carrying a gun to school, according to a nationally representative survey conducted by the RAND Corporation.

The survey found that 54% of teachers believe teachers carrying firearms would make schools less safe, 20% believe teacher-carry would make schools safer, and 26% feel it would make schools neither more nor less safe.

Yet even more concerning to teachers than guns is bullying, which teachers listed as their top safety concern.

The survey, conducted in October and November 2022, focused on how K-12 teachers view safety in their schools.

“Even with the unfortunate regularity of gun violence in U.S. schools, which often drives the policy debate around school safety, only 5% of teachers overall selected gun violence as their largest safety concern,” said Heather L. Schwartz, a report author and senior policy researcher at RAND, a nonprofit, nonpartisan research organization. “Despite the prevalence of anti-bullying programs, everyday school violence is a concern for teachers. Bullying, not active shooters, was teachers’ most common top safety concern, followed by fights and drugs.”

Teachers’ beliefs about whether teacher-carry policies would make schools safer varied both by their own race and ethnicity as well as by the racial and ethnic composition of the student population in their school. White teachers were more likely than Black teachers to feel that teachers carrying firearms would make schools safer, and male teachers in rural schools were most likely to say they would personally carry a firearm at school if allowed.

Important to school safety is a system of threat reporting and intervention, as well as a climate that encourages adults to prevent violence before it occurs. Most teachers surveyed were confident that threats would get reported.

Visible school safety measures, beyond armed staff, were also viewed as affecting school climate positively. The most common physical safety measures – which 80% or more of teachers said their school had in place – were visitor systems, exterior and interior locks, and staff IDs.

Based on the survey results, the researchers suggest several areas for further research. One is developing better approaches for school safety and security planning that might balance the frequent, lower-level forms of school violence such as bullying with lower-probability, extreme forms of school violence like shootings.

Other authors of the report, “Teachers’ Views on School Safety: Consensus on Many Security Measures, But Stark Division About Arming Teachers,” are Brian A. Jackson, Melissa Kay Diliberti and Pauline Moore.

This research was undertaken by the RAND Homeland Security Research Division and RAND Education and Labor.

Four ways to advance equity and justice goals in climate action planning

Peer-Reviewed Publication

UNIVERSITY OF WATERLOO

Municipal climate action plans often identify equity and justice as goals, but engagement with these concepts is mostly rhetorical. A new study from the University of Waterloo details how planners can bridge the gap and challenge the current state of climate change and social inequity.   

The study asserts that developing participatory approaches to public consultation and community engagement that actively and intentionally involve vulnerable populations who are most affected by climate change is critical. Expanding the sphere of knowledge we consider when talking about climate change reshapes the questions that are asked and the possible solutions and alternatives that are up for discussion. 

“The urban governance community is not as explicit as it should be about the need to prioritize vulnerable residents during decision-making processes about climate change,” said Kayleigh Swanson, PhD candidate in Waterloo’s School of Planning. “Consequently, the voices of people experiencing various forms of oppression are largely excluded from so-called participatory climate action planning processes.”  

In pursuing participatory methods, the study advises practitioners to keep four actions top of mind: consistently modifying strategies, designing collaborative spaces that recognize various ways of knowing, addressing the gap between what is said and what is done, and attending to the underlying social processes that drive vulnerability to climate change.  

“Challenging the status quo is not an easy task, but the evidence shows that climate actions are more effective if they are designed and implemented with engagement by local actors,” said Dr. Mark Seasons, professor in Waterloo’s School of Planning. “Urban governance actors can influence the conditions that determine whether people can participate effectively and help to frame important issues being considered by decision-makers.”  

Building inclusionary planning processes is a considerable challenge for urban governance actors, but these processes are necessary to realize equitable distributive outcomes. Exclusion runs the risk of creating a triple injustice whereby those who contribute to climate change the least are positioned to suffer the most from its effects and are disproportionately affected by climate action policies that exacerbate the social, economic, and environmental challenges the groups already face.  

The study, Centering Equity and Justice in Participatory Climate Action Planning: Guidance for Urban Governance Actors, appears in the journal Planning Theory & Practice. 

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JOURNAL

Planning Theory & Practice

Actively reducing noise by ionizing air

Peer-Reviewed Publication

ECOLE POLYTECHNIQUE FÉDÉRALE DE LAUSANNE

 

IMAGE: PLASMA VALVES DARK view more 

CREDIT: © STANISLAV SERGEEV & MATHIAS DELAHAYE

Did you know that wires can be used to ionize air to make a loudspeaker? Simply put, it’s possible to generate sound by creating an electric field in a set of parallel wires, aka a plasma transducer, strong enough to ionize the air particles. The charged ions are then accelerated along the magnetic field lines, pushing the residual non-ionized air in a way to produce sound.

If a loudspeaker can generate sound, it can also absorb it.

While this plasma loudspeaker concept is not new, EPFL scientists went ahead and built a demonstration of the plasma transducer, with the aim to study noise reduction. They came up with a new concept, what they call the active “plasmacoustic metalayer” that can be controlled to cancel out noise. Their results are published in Nature Communications.

The scientists were intrigued by the idea of using plasma to reduce noise, since it gets rid of one of the most important aspects of conventional loudspeakers: the membrane.  Loudspeakers equipped with membranes, like the ones in your car or at home, are some of the most studied solution for active noise reduction. It’s active because the membrane can be controlled to cancel out different sounds, as opposed to a wall that does the job passively.

The problem with using the conventional loudspeaker as a sound absorber is that its membrane limits the frequency range of operation. For sound absorption, the membrane behaves mechanically, vibrating to cancel out the sound waves in the air. The fact that the membrane is relatively heavy, i.e. the inertia of the membrane, limits its ability to interact efficiently with fast changing sounds or at high frequencies.

“We wanted to reduce the effect of the membrane as much as possible, since it’s heavy. But what can be as light as air? The air itself,”explains Stanislav Sergeev, postdoc at EPFL’s Acoustic Group and first author. “We first ionize the thin layer of air between the electrodes that we call a plasmacoustic metalayer. The same air particles, now electrically charged, can instantaneously respond to external electrical field commands and effectively interact with sound vibrations in the air around the device to cancel them out.”

Sergeev continues, “As expected, the communication between the electrical control system of the plasma and the acoustic environment is much faster than with a membrane.”

Not only is the plasma efficient at high frequencies, but it is also versatile since it can be tuned to work at low frequencies as well. Indeed, the scientists show that the dynamics of thin layers of air plasma can be controlled to interact with sound over deep-subwavelength distances, to actively respond to noise and cancel it out over a broad bandwidth. The fact that their device is active is key, since passive noise reduction technologies are limited in the band of frequencies that can be controlled.

The plasma absorber is also more compact that most conventional solutions. Exploiting the unique physics of plasmacoustic metalayers, the scientists experimentally demonstrate perfect sound absorption: “100% of the incoming sound intensity is absorbed by the metalayer and nothing is reflected back,” says EPFL’s Acoustic Group’s senior scientist Hervé Lissek. They also show tunable acoustic reflection from several Hz to the kHz range, with transparent plasma layers of thicknesses down to only a thousandth of a given wavelength, much smaller than conventional noise reduction solutions. 

To give an idea of how much more compact the plasma absorber is, consider a low, audible sound frequency of 20 Hz, where the sonic wavelength is 17m meters long. The plasma layer would only need to be 17 mm thick to absorb the noise, whereas most conventional noise reduction solutions, like absorbing walls, would need to be at least 4 m thick which often limits its feasibility.

“The most fantastic aspect in this concept is that, unlike conventional sound absorbers relying on porous bulk materials or resonant structures, our concept is somehow ethereal. We have unveiled a completely new mechanism of sound absorption, that can be made as thin and light as possible, opening new frontiers in terms of noise control where space and weight matter, especially at low frequencies” says Hervé Lissek.

EPFL has partnered with Sonexos SA, a Swiss-based audio technology company, to develop cutting-edge active sound absorbers that use the plasmacoustic metalayer concept. Together, they aim to provide novel and efficient solutions for reducing noise in a wide range of applications, including the automotive, consumer, commercial, and industrial sectors.

“This strategic collaboration leverages EPFL's expertise in material science and acoustics, as well as Sonexos' proven track record in delivering high-performance audio solutions,” explains Mark Donaldson, CEO and Founder of Sonexos. 

EPFL scientists show that a thin layer of plasma, created by ionizing air, could be promising as an active sound absorber, with applications in noise control and room acoustics.

CREDIT

© Alain Herzog / EPFL

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JOURNAL

Nature Communications

DOI

10.1038/s41467-023-38522-5 

ARTICLE TITLE

Ultrabroadband sound control with deep- subwavelength plasmacoustic metalayers