Study probes how plague spreads through wild rodent populations

Mathematical modeling revealed how fleas with early-stage Yersinia pestis infections are insufficient to drive epizootic outbreaks but can help promote a low level of enzootic plague.

Peer-Reviewed Publication

PLOS

 

IMAGE: OROPSYLLA MONTANA (A GROUND SQUIRREL FLEA) INFECTED AND BLOCKED WITH YERSINIA PESTIS. view more 

CREDIT: MITCHELL ET AL, CC-BY 4.0, HTTPS://CREATIVECOMMONS.ORG/LICENSES/BY/4.0/)

Scientists have long been puzzled how the bubonic plague bacteria, Yersinia pestis, can cause both stable, enzootic disease among rodents, as well as sudden, lethal epizootic outbreaks that decimate the same rodent populations. A new study concludes that the difference might relate to the fleas that carry Y. pestis between animals. Fleas with only early-phase infection are insufficient to drive an epizootic among most wild rodents, and favor a more stable enzootic state, according to the research published this week in PLOS Pathogens by Joseph Hinnebusch of the National Institute of Allergy and Infections Diseases Rocky Mountain Laboratories, U.S., and colleagues.

Plague primarily afflicts rodents, including rats, mice, gerbils, squirrels, marmots and prairie dogs. The bacteria circulate within these host populations through several flea vector species. Fleas can transmit Y. pestis in different stages following an infectious blood meal; transmission can occur the very next time they feed, a phenomenon referred to as early-phase transmission. Later, “blockage-dependent transmission” occurs after Y. pestis forms a bacterial biofilm in the fleas’ digestive systems, blocking the flow of an incoming meal and causing blood to recoil back into the bite site after mixing with the biofilm.

In the new study, researchers for the first time empirically evaluated the relative efficiency of the different phases of transmission by individual fleas. Cohorts of a ground squirrel flea, Oropsylla montana, were infected by feeding on mouse or rat blood infected with Y. pestis. Transmission efficiency of individual O. montana fleas was then measured over a four-week period and the researchers created models to show how this efficiency would translate to the spread of Y. pestis through a rodent population.

The results indicated that blockage-dependent transmission is much more efficient than early-phase transmission, in terms of the probability of transmission, the number of bacteria transmitted, and the capability of driving an epizootic outbreak. Early-phase transmission, the models showed, could drive an epizootic only in naïve, very susceptible host populations and when the flea burden is high. Moreover, the low dose of bacteria typically transmitted in early-phase transmission may “immunize” many individuals, acting to promote an enzootic state.

“Our models suggest that exposure of most wild rodents to sublethal, immunizing doses of Y. pestis transmitted during the early phase may ameliorate rapid epizootic spread by reducing the number of susceptible individuals in the population,” the authors say. “In many situations early-phase transmission may be more important in maintaining the enzootic state than in driving an epizootic.”

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In your coverage, please use this URL to provide access to the freely available article in PLOS Pathogens: http://journals.plos.org/plospathogens/article?id=10.1371/journal.ppat.1010996

Citation: Mitchell CL, Schwarzer AR, Miarinjara A, Jarrett CO, Luis AD, Hinnebusch BJ (2022) A Role for Early-Phase Transmission in the Enzootic Maintenance of Plague. PLoS Pathog 18(12): e1010996. https://doi.org/10.1371/journal.ppat.1010996

Author Countries: USA

Funding: This research was funded by the Intramural Research Program of the NIH (to BJH), NIAID (ZIA AI000796-25) and by the National Science Foundation (2109828 to ADL). The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.

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JOURNAL

PLoS Pathogens

DOI

10.1371/journal.ppat.1010996 

METHOD OF RESEARCH

Experimental study

SUBJECT OF RESEARCH

Animals

ARTICLE TITLE

A Role for Early-Phase Transmission in the Enzootic Maintenance of Plague

ARTICLE PUBLICATION DATE

15-Dec-2022

Herpes vaccines could mean billions of dollars of cost savings and prevent the loss of millions of quality of life years by reducing HSV-2 infections and HSV-2 driven HIV infections, according to a modelling study in 90 low and middle income countries

Peer-Reviewed Publication

PLOS

In your coverage, please use this URL to provide access to the freely available paper in PLOS Medicine: http://journals.plos.org/plosmedicine/article?id=10.1371/journal.pmed.1003938

Article Title: Estimated economic burden of genital herpes and HIV attributable to herpes simplex virus type 2 infections in 90 low- and middle-income countries: A modeling study

Author Countries: United States, Qatar

Funding: HHA acknowledges the joint support of Qatar University and Marubeni M-QJRC-2020-5. LJA acknowledges the support of NPRP grant number 9-040-3-008 from the Qatar National Research Fund (a member of Qatar Foundation). The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.

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JOURNAL

PLoS Medicine

DOI

10.1371/journal.pmed.1003938 

METHOD OF RESEARCH

Observational study

SUBJECT OF RESEARCH

People

8 Million Popular Cleaning Products Recalled Over Bacterial Contamination Concern

Story by Shannen Zitz • 

Everything to Know About FDA Recalls

The Laundress has recalled approximately eight million units of cleaning products over bacterial contamination.

Burkholderia cepacia complex, Klebsiella aerogenes, and various species of Pseudomonas were discovered in the products.

Those with affected products should stop use immediately and follow appropriate disposal instructions.

On December 1st, The Laundress announced a voluntary recall of millions of household cleaning products due to bacterial contamination. The brand made the announcement via an Instagram post and is in cooperation with the U.S. Consumer Product Safety Commission (CPSC) and Health Canada.

The recalled products, which include various lots of all of the brand’s laundry and cleaning products, may contain a variety of bacteria, “including Burkholderia cepacia complex, Klebsiella aerogenes, and multiple different species of Pseudomonas,” according to the CPSC. Those with weakened immune systems, external medical devices, and underlying lung conditions who are exposed to the bacteria face a serious risk of infection that could require medical treatment. The bacteria can enter the body through the eyes, breaks in the skin, or if inhaled. Symptoms of these types of bacteria include fever, chills, serious upper respiratory infections to no symptoms at all, and vary based on each type. People with healthy immune systems are usually not affected by the bacteria, per the CPSC.


The Laundress voluntarily recalled around eight million units of laundry and cleaning products after multiple different species of bacteria were detected.

© Evgeniia Siiankovskaia - Getty Images

The recalled products are:

Products with lot codes that begin with the letter F and the last four digits are numbered 9354 or lower
Products with lot codes that begin with the letter H and the last four digits are numbered 2262 or lower
Products with lot codes that begin with the letter T and the last four digits are numbered 5264 or lower

The products were sold at TheLaundress.com, Amazon.com, Target, Bloomingdales, The Container Store, and other major retailers through September 2022, per the CPSC.

Anybody with contaminated products should immediately stop using and “dispose of the product by closing the bottle tightly and placing it in household trash,” The Laundress explained. “Do not empty the product prior to disposal.”

The company shared information about the recall with their customers today, urging those with affected products to cease use and navigate to their website (www.TheLaundressRecall.com) for more information about refunds, specific products involved in the recall, and product disposal.

The brand took to social media to delve a bit deeper into what happened. “We deeply apologize to all our loyal customers for this situation,” the brand wrote. “We are undertaking decisive steps with our suppliers to ensure production processes meet our safety and quality standards. Sincerely, The Laundress Team.”

Their announcement on Instagram followed a string of other updates from the brand regarding product safety beginning two weeks before the official recall. On November 17, the brand posted a “safety notice” warning customers of the “potential presence of elevated levels of bacteria in some of our products that present a safety concern.” The CPSC noted at the time of their press release that there are 11 customers who have reported Pseudomonas infections, which are under investigation for connection to the recalled products.

On November 19th, the brand posted an update, noting the creation of an FAQ page for concerns related to the recall, writing: “We are working hard to provide as much clarity to you as possible and we understand the concerns you may feel as we await answers.”

Customers were understandably upset about the safety issues and the brand’s slowness in providing information. “This is really alarming,” one customer commented on the brand’s Instagram post announcing the recall. “I love your products but to have this kind of issue with products that are so expensive and then such a vague safety notice?”

Another added: “The more I think about this the more infuriated I become. The Laundress is the only detergent I have ever used on my 15-month-old daughter’s clothes, blankets, towels, etc. At the price points we pay for these ‘luxury’ products, this is absolutely something we should never, EVER have to worry about.”

If you have questions about the recall or would like to request reimbursement for the purchase of the affected product, you can visit The Laundress’ voluntary recall website or email the company at customerservice@thelaundress.com.

Talk to your physician if you have any health concerns related to using the product involved in the recall.

The monkeypox virus DNA-synthesizing machine

Peer-Reviewed Publication

AMERICAN ASSOCIATION FOR THE ADVANCEMENT OF SCIENCE (AAAS)

Using cryo-microscopy, researchers present a high-resolution structure of monkeypox virus DNA polymerase holoenzyme, a complex that plays a key role in the genome replication process of the virus. The findings reveal the mechanism that underlies monkeypox virus genome replication and could be used to guide the development of antiviral drugs. In July 2022, the World Health Organization declared monkeypox virus (MPXV) as a public health emergency of international concern and, as of early December 2022, more than 82,000 human monkeypox cases have been confirmed in 110 countries worldwide. New preventative and therapeutic measures against this virus are needed. In this study, Qi Peng and colleagues used cryo-electron microscopy to determine a high-resolution structure of the monkeypox virus DNA polymerase holoenzyme. According to the findings, the holoenzyme possesses an architecture that indicates a “forward sliding clamp” mechanism for DNA replication. The authors suggest that this finding could be leveraged to design anti-poxvirus drugs.

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JOURNAL

Science

DOI

10.1126/science.ade6360 

ARTICLE TITLE

Structure of monkeypox virus DNA polymerase holoenzyme

ARTICLE PUBLICATION DATE

15-Dec-2022

Prolonged geographic separation in ecologically similar environments can drive new species

Peer-Reviewed Publication

AMERICAN ASSOCIATION FOR THE ADVANCEMENT OF SCIENCE (AAAS)

Trait data from more than 1,000 different vertebrate species suggests that new species often arise not because of pressures from different environments, but because of prolonged geographic separation in ecologically similar environments. The findings contrast the classical view of divergent adaptation as the dominant driver of early speciation. While it is widely agreed upon that most speciation events require an allopatric phase – a period in which a species population becomes geographically separated long enough to have it diverge into a distinct new species – whether ecological divergence drives this critical allopatric phase is unknown. To better understand the role divergent ecological adaptation plays in allopatric speciation, Sean Anderson and Jason Weir combined new data from 129 allopatric sister pairs of bird species (speciating or recently speciated taxa) with 14 other published allopatric sister pair datasets for various other birds, mammals and amphibian species. They used the trait data to model the relative contribution of divergence adaptation to allopatric divergence. Anderson and Weir discovered that divergent ecological adaptation is a relatively minor force during allopatric divergence and that most species tend to evolve under similar selective pressures. “Using new models to analyze sister-pair trait differences, we find that adaptive ecological divergence to be the exception rather than the rule in vertebrates,” write the authors. “This result contradicts the classical idea that divergent adaptation initiates the earliest stages of speciation, and it supports an emerging picture in which new species commonly arise despite minimal ecological divergence.”

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JOURNAL

Science

DOI

10.1126/science.abo7719 

ARTICLE TITLE

The role of divergent ecological adaptation during allopatric speciation in vertebrates

ARTICLE PUBLICATION DATE

15-Dec-2022

A call to designate World Heritage Environmental Datasets

Data longevity & accessibility are essential to understanding global change

Reports and Proceedings

CARY INSTITUTE OF ECOSYSTEM STUDIES

 

IMAGE: WEIR AT HUBBARD BROOK EXPERIMENTAL FOREST IN THE WHITE MOUNTAINS OF NEW HAMPSHIRE. view more 

CREDIT: CLAIRE NEMES

“Some environmental datasets are so integral to our understanding of the world around us and our place in it that leaving their continuation to the vagaries of fate or government funding cycles is illogical and irresponsible.”  So reports a Letter, published today in Science by a team of leading ecologists calling for the designation of World Heritage Datasets. 

Long-term datasets such as CO2 measurements at Mauna Loa Observatory in Hawaii (Keeling Curve), cherry blossom dates in Kyoto, Japan, and precipitation and stream water chemistry at Hubbard Brook in New Hampshire have provided information vital to science-based environmental policy, resource management, and climate change adaptation. But the future of these and other vital datasets hangs in the balance due to funding threats and weak support infrastructure. 

The authors note that “high-impact, long-term datasets that document our changing environment are a part of our cultural heritage,” and “by establishing the value of long-term environmental records, World Heritage designation would help secure funds, ensure data longevity and accessibility, and encourage the creation of new datasets of significance for understanding global change.”

 

Authors of the letter include:

Emma J. Rosi, Cary Institute of Ecosystem Studies, Millbrook, NY

Emily S. Bernhardt, Dept. of Biology, Duke University, Durham, NC

Christopher T.  Solomon, Cary Institute of Ecosystem Studies, Millbrook, NY

Gene E. Likens, Cary Institute of Ecosystem Studies, Millbrook, NY; Institute of the Environment, University of Connecticut, Storrs, CT

William. H. McDowell, Department of Natural Resources and the Environment, University of New Hampshire, Durham, NH

Irena F. Creed, Department of Physical and Environmental Sciences, University of Toronto, Toronto

Corresponding author Emma J. Rosi - rosie@caryinstitute.org

  

Cherry Blossoms in Kyoto, Japan

; https://www.flickr.com/photos/rurinoshima/16498769573/

Mauna Loa Observatory on Mauna Loa, on the island of Hawaii.

CREDIT

I. Vtorov / Wikimedia Commons https://upload.wikimedia.org/wikipedia/commons/e/e2/2017-MaunaLoaObservatory.jpg

JOURNAL

Science

METHOD OF RESEARCH

Commentary/editorial

SUBJECT OF RESEARCH

Not applicable

ARTICLE TITLE

Designate World Heritage Datasets

ARTICLE PUBLICATION DATE

15-Dec-2022

Disclaimer: A

PHILOSOPHERS STONE

Dynamical fractal discovered in clean magnetic crystal

Peer-Reviewed Publication

UNIVERSITY OF CAMBRIDGE

 

IMAGE: EXAMPLE OF THE FRACTAL STRUCTURES IN SPIN ICE TOGETHER WITH A FAMOUS EXAMPLE OF A FRACTAL (THE MANDELBROT SET), ON TOP OF A PHOTOGRAPH OF WATER ICE. view more 

CREDIT: JONATHAN N. HALLÉN, CAVENDISH LABORATORY, UNIVERSITY OF CAMBRIDGE

The nature and properties of materials depend strongly on dimension. Imagine how different life in a one-dimensional or two-dimensional world would be from the three dimensions we’re commonly accustomed to. With this in mind, it is perhaps not surprising that fractals – objects with fractional dimension – have garnered significant attention since their discovery. Despite their apparent strangeness, fractals arise in surprising places – from snowflakes and lightning strikes to natural coastlines.

Researchers at the University of Cambridge, the Max Planck Institute for the Physics of Complex Systems in Dresden, the University of Tennessee, and the Universidad Nacional de La Plata have uncovered an altogether new type of fractal appearing in a class of magnets called spin ices. The discovery was surprising because the fractals were seen in a clean three-dimensional crystal, where they conventionally would not be expected. Even more remarkably, the fractals are visible in dynamical properties of the crystal, and hidden in static ones. These features motivated the appellation of "emergent dynamical fractal".

The fractals were discovered in crystals of the material dysprosium titanate, where the electron spins behave like tiny bar magnets. These spins cooperate through ice rules that mimic the constraints that protons experience in water ice. For dysprosium titanate, this leads to very special properties.

Jonathan Hallén of the University of Cambridge is a PhD student and the lead author on the study. He explains that “at temperatures just slightly above absolute zero the crystal spins form a magnetic fluid.” This is no ordinary fluid, however.

“With tiny amounts of heat the ice rules get broken in a small number of sites and their north and south poles, making up the flipped spin, separate from each other traveling as independent magnetic monopoles.”

The motion of these magnetic monopoles led to the discovery here. As Professor Claudio Castelnovo, also from the University of Cambridge, points out: “We knew there was something really strange going on. Results from 30 years of experiments didn’t add up.”

Referring to a new study on the magnetic noise from the monopoles published earlier this year, Castelnovo continued, “After several failed attempts to explain the noise results, we finally had a eureka moment, realizing that the monopoles must be living in a fractal world and not moving freely in three dimensions, as had always been assumed.”

In fact, this latest analysis of the magnetic noise showed the monopole’s world needed to look less than three-dimensional, or rather 2.53 dimensional to be precise! Professor Roderich Moessner, Director of the Max Planck Institute for the Physics of Complex Systems in Germany, and Castelnovo proposed that the quantum tunneling of the spins themselves could depend on what the neighboring spins were doing.

As Hallén explained, “When we fed this into our models, fractals immediately emerged. The configurations of the spins were creating a network that the monopoles had to move on. The network was branching as a fractal with exactly the right dimension.”

But why had this been missed for so long?

Hallén elaborated that, “this wasn’t the kind of static fractal we normally think of. Instead, at longer times the motion of the monopoles would actually erase and rewrite the fractal.”

This made the fractal invisible to many conventional experimental techniques.

Working closely with Professors Santiago Grigera of the Universidad Nacional de La Plata, and Alan Tennant of the University of Tennessee, the researchers succeeded in unravelling the meaning of the previous experimental works.

 “The fact that the fractals are dynamical meant they did not show up in standard thermal and neutron scattering measurements,” said Grigera and Tennant. “It was only because the noise was measuring the monopoles motion that it was finally spotted.”

As regards the significance of the results, which appear in Science this week, Moessner explains: “Besides explaining several puzzling experimental results that have been challenging us for a long time, the discovery of a mechanism for the emergence of a new type of fractal has led to an entirely unexpected route for unconventional motion to take place in three dimensions.”

Overall, the researchers are interested to see what other properties of these materials may be predicted or explained in light of the new understanding provided by their work, including ties to intriguing properties like topology. With spin ice being one of the most accessible instances of a topological magnet, Moessner said, “the capacity of spin ice to exhibit such striking phenomena makes us hopeful that it holds promise of further surprising discoveries in the cooperative dynamics of even simple topological many-body systems.”.

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 [PP1]Reference perhaps?

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JOURNAL

Science

DOI

10.1126/science.add1644 

ARTICLE TITLE

Dynamical fractal and anomalous noise in a clean magnetic crystal

ARTICLE PUBLICATION DATE

15-Dec-2022

One is the loneliest number: game theory shows why sexual misconduct is underreported

Peer-Reviewed Publication

UNIVERSITY OF TORONTO, ROTMAN SCHOOL OF MANAGEMENT

 

IMAGE: ING-HAW CHENG IS AN ASSOCIATE PROFESSOR OF FINANCE AT ATHE UNIVERSITY OF TORONTO'S ROTMAN SCHOOL OF MANAGEMENT. HE RESEARCHES HOW BELIEFS AND INCENTIVES AFFECT CAPITAL MARKETS AND THE ECONOMY. RECENT WORK INCLUDES STUDIES OF VOLATILITY AND COMMODITY DERIVATIVES MARKETS, THE IMPACT OF COVID-19 AND THE 2008 GREAT FINANCIAL CRISIS ON MARKETS, AND NEW AND EMERGING TOPICS IN ECONOMICS AND FINANCE. view more 

CREDIT: ROTMAN SCHOOL OF MANAGEMENT

Toronto - The idea that there’s safety in numbers was a major driver behind the #MeToo movement, which encouraged people who had been targets of sexual misconduct to come forward.

While there have been many heated debates about why people who have experienced abuse don’t report, a pair of economists used their academic discipline’s tools to dispassionately explain why underreporting is at its highest when misconduct is widespread, and why awareness-raising campaigns like #MeToo can help.

“There are real economic reasons why people don’t come forward,” says Ing-Haw Cheng, an associate professor of finance at the University of Toronto’s Rotman School of Management who co-authored the research with Alice Hsiaw of Brandeis University.

The pair built a model of the decision to report using game theory, which applies mathematics to represent situations where the outcome for each individual’s decision is affected by everybody else’s choices.

In an environment where sexual misconduct by one or more individuals is an open secret, those who have been their targets face uncertainty over whether others will come forward. If one person chooses to report misconduct, they do not know if their information will be backed by other reports, or if it will be an outlier, weakening their credibility and making them vulnerable to reprisals. In the language of game theory, the complainant who sticks their neck out to report faces a “first mover disadvantage,” with significant potential costs.

"Uncertainty over whether others will come forward can be so strong enough that no one will report even when misconduct is widespread, creating a 'culture of silence',” says Prof. Cheng.

Reporting improves when individuals are aware that other reports have been made, when problematic behaviour is penalized, or when people who have been targeted by sexual misconduct receive damage awards, such as through a lawsuit, the model shows.

However, it also shows that movements like #MeToo can have unintended consequences, something Prof. Cheng says are unavoidable. As awareness of sexual misconduct rises, some managers choose not to act as mentors to junior employees. If those managers have a tendency towards misconduct, it reduces the number of incidents and the number of reports, leading once again to reluctance to report. If the managers who shy away from mentoring behave ethically, junior employees lose out by not having access to good mentors.

Some organizations attempt to deal with the uncertainty hurdle through a “holding tank” system where misconduct reports are received and held confidentially, but only acted on once there are multiple complaints for an individual. However, the researchers found that the approach does not always help because complainants may again be unsure whether their report will lead to action.

The findings are useful for understanding how to overcome the culture of silence that prevents people from speaking up when they see behaviour that runs counter to a group or organization’s rules, ethics or values.

“A model in economics provides a chain of logic that rests on a set of assumptions,” says Prof. Cheng. “We can use this as a basis for a sensible conversation in an emotionally charged topic.”

The paper appears in the November issue of American Economic Journal: Microeconomics.

Bringing together high-impact faculty research and thought leadership on one searchable platform, the new Rotman Insights Hub offers articles, podcasts, opinions, books and videos representing the latest in management thinking and providing insights into the key issues facing business and society.

Visit www.rotman.utoronto.ca/insightshub.

The Rotman School of Management is part of the University of Toronto, a global centre of research and teaching excellence at the heart of Canada’s commercial capital. Rotman is a catalyst for transformative learning, insights and public engagement, bringing together diverse views and initiatives around a defining purpose: to create value for business and society. For more information, visit www.rotman.utoronto.ca

 

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JOURNAL

American Economic Journal Microeconomics

DOI

10.1257/mic.20200218 

METHOD OF RESEARCH

Data/statistical analysis

SUBJECT OF RESEARCH

People

ARTICLE TITLE

Reporting Sexual Misconduct in the #MeToo Era

Marsquake!

Seismic waves from the largest marsquake ever detected revealed possible past meteoroid impact

Peer-Reviewed Publication

UNIVERSITY OF CALIFORNIA - LOS ANGELES

The largest earthquake ever detected on Mars has revealed layers in its crust that could indicate past collision with a massive object, such as a meteoroid. Previous data has suggested the past occurrence of a large impact, and the findings offer evidence that might support this hypothesis.

The research, led by UCLA planetary scientists and published in two papers in Geophysical Research Letters, could also indicate that alternating layers of volcanic and sedimentary rocks lie beneath the surface.

The 4.7 magnitude earthquake, or marsquake, happened in May 2022 and lasted more than four hours, releasing five times more energy than any previously recorded quake. Though moderate by Earth standards, the temblor was nonetheless powerful enough to send seismic surface waves completely around the planet’s circumference, the first time this phenomenon has been observed on Mars.

The readings were taken from InSight, which landed on Mars in 2018. InSight is the first outer space seismometer to study in-depth the “inner space” of Mars: its crust, mantle and core.

“The seismometer aboard the InSight lander has recorded thousands of marsquakes but never one this large, and it took over three years after landing to record it,” said corresponding author Caroline Beghein, a professor of Earth, planetary and space sciences. “This quake generated different kinds of waves, including two types of waves trapped near the surface. Only one of those two has been observed on Mars before, after two impact events, never during a marsquake.”

Mapping the seismic activity, the location and frequency of impacts on Mars and the interior structure is important for future missions to the red planet as it will inform scientists and engineers where and how to build structures to ensure the safety of future human explorers.

As on Earth, studying how seismic waves travel through rocks can give scientists clues about the temperature and composition of the planet below the surface that help inform the search for underground water or magma. It also helps scientists understand the past forces that shaped the planet.

Beghein’s group combined measurements from two types of surface waves, called Love and Rayleigh waves, to infer the speed of underground shear-waves, which travel horizontally and move rocks perpendicular to the direction of wave propagation. This is the first time Love waves have been observed in conjunction with Rayleigh waves on Mars.

The measurements showed that the shear-waves move faster in the crust when rocks between 10 and 25 kilometers underground oscillate in a direction almost parallel to the planet surface than if the rocks vibrate in the vertical direction.

“This wave speed information is related to deformations inside the crust,” Beghein said. “Alternating volcanic rocks and sedimentary layers, which were deposited long ago, or a very large impact, such as a meteoroid, most likely account for the seismic wave measurements we observed.”

These data also enabled Jiaqi Li, a UCLA postdoctoral researcher in Beghein’s group, to learn that shear-waves move faster in the Martian southern highland areas than in the northern lowlands. The northern hemisphere of Mars has a lower elevation and is covered with more craters than the southern hemisphere. A large impact in the lowlands has been the prevalent theory to explain the origin of this difference.

The new data point toward the presence of thick accumulations of sedimentary rocks and relatively higher porosity in the lowlands.  Larger amounts of gas, such as trapped air in these sedimentary rocks, slow the waves down.  

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JOURNAL

Geophysical Research Letters

DOI

10.1029/2022GL101508 

METHOD OF RESEARCH

Observational study

SUBJECT OF RESEARCH

Not applicable

ARTICLE TITLE

Crustal Anisotropy in the Martian Lowlands From Surface Waves

ARTICLE PUBLICATION DATE

14-Dec-2022

Some claim culture affects our basic visual perception. A UCLA study takes a fresh look

Researchers found little difference in how people of East Asian and European descent performed on a famous test

Peer-Reviewed Publication

UNIVERSITY OF CALIFORNIA - LOS ANGELES

Research claims made over recent years that people of East Asian and European descent perform differently on a well-known visual perception test as a result of fundamental cultural differences may be overstated, according to UCLA psychologists.

In new experiments conducted by the UCLA researchers, white, Asian American and recent Asian immigrant college students in the U.S. performed similarly on the test, known as the rod-and-frame task, which measures the influence of surrounding contextual visual information on perception.  

The findings, published in PLOS One suggest that the basics of visual perception, such as object orientation, are largely independent of cultural variation and apply broadly across human populations.

What is the rod-and-frame task and what is the debate?

The rod-and-frame task asks participants to view a single line within a square frame and to orient that line straight up and down vertically. The difficulty comes when the surrounding frame is tilted in various ways, which can influence viewers’ perception of the vertical orientation of the line.

Historically, much of this type of research had been conducted in Western countries with college students as participants, raising questions about how accurate the data is for people in other cultures and parts of the world.

In some previous, highly publicized work produced since 2000, researchers exploring that question found that East Asians and Europeans performed differently on the rod-and-frame task; East Asians, the researchers said, tended to focus on the square frame first or give equal attention to the frame and the line, while Europeans placed more emphasis on the line.

These researchers hypothesized that cultural influences could be at the root of the differences, with participants from East Asian cultures, which social scientists say emphasize the embeddedness of individuals within collective groups, perceiving more holistically and taking context into consideration. Similarly, participants from Western cultures, which social scientists say tend to elevate individuals over groups, may perceive more analytically and independently of context. The claims bucked against a fundamental assumption in visual neuroscience research that basic visual functions are the same for humans everywhere, as well as for non-human primates.

“If culture influences even the most basic visual functions, then all studies must take into consideration the cultures of the participants and the fact that findings might not apply to other cultures,” said Zili Liu, a UCLA psychology professor and the current study’s corresponding author. “Perhaps more importantly, vision research with animals will have limited utility.”

If these previous findings were true, Liu noted, it would stand to reason that people who have been immersed in another’s culture for enough time will start to perform similarly to people raised in that culture on the rod-and-frame task.

“I thought UCLA was a good place to test this because we have many Asian American students, as well as more recent Asian immigrants to the U.S., and they should serve as supportive evidence that the longer people have lived here, the less the data would look like Asian nations,” Liu said.

Reassessing the influence of culture on the rod-and-frame task

Chéla R Willey, a UCLA doctoral student at the time of the study who is now an assistant professor at Loyola Marymount University, recruited a diverse group of 342 UCLA students to perform the rod-and-frame task using virtual reality goggles. All participating students answered a questionnaire about their ethnicity and country of citizenship. In this first experiment, participants used a computer mouse to rotate the center line to make it vertical.

In a second experiment, 216 of the 342 students judged whether the line was clockwise or counter-clockwise with respect to the vertical.

Among the 84 East Asian participants who completed both experiments, 40 were second-generation Americans (born in the U.S. with at least one immigrant parent) or beyond and 44 were first generation or non-citizens. Among the white dual-experiment participants, nearly all — 51 out of 57 — were second-generation Americans or beyond, while six were first generation or non-citizens.

The results of the first experiment revealed that a participant’s cultural background had little, if anything, to do with how they judged the line’s vertical orientation inside both tilted and non-tilted frames. In the second experiment, the researchers once again found no significant difference between ethnicity or generation. They did, however, observe a well-known gender difference in which frame tilt affects the perception of women more than men.

“The gender finding replicates what has been found in many other studies, indicating that our data are of reasonable quality,” Liu said. “Our failure to replicate the cultural effect therefore suggests that culture might not influence orientation perception that much.”

The work lends support to research showing that some basic mechanisms of visual perception are universal and that for these kinds of studies, it might not matter much which population the researchers use.

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JOURNAL

PLoS ONE

DOI

10.1371/journal.pone.0276393 

METHOD OF RESEARCH

Experimental study

SUBJECT OF RESEARCH

People

ARTICLE TITLE

Re-assessing the role of culture on the visual orientation perception of the rod and frame test