It’s possible that I shall make an ass of myself. But in that case one can always get out of it with a little dialectic. I have, of course, so worded my proposition as to be right either way (K.Marx, Letter to F.Engels on the Indian Mutiny)
Tuesday, February 03, 2026
Paid sick leave as disease prevention
With new evidence from home service workers, George Mason University researchers found that paid sick leave can function as a public health intervention.
Home service workers—those who provide care, inspections, or repairs inside private homes—can often lack paid sick leave, making illness a direct financial risk. New research from George Mason University College of Public Health suggests paid sick leave should be understood not only as an employee benefit, but as a preventive health intervention.
In the study led by assistant nursing professor Suyoung Kwon, paid sick leave was linked to lower perceived infection risk, reduced job stress, and higher job satisfaction. During the early months of COVID-19, the research team surveyed more than 1,600 home service workers in South Korea, including home nurses, childcare workers, appliance repair technicians, and gas meter inspectors.
Notably, workers reported that their highest level of stress was not after a confirmed diagnosis of COVID, but during the window when workers are deciding whether to show up sick or stay home.
“Paid sick leave can function much like personal protective equipment or vaccination for workers in high-contact roles,” said Kwon. “It reduces exposure before harm occurs.”
The study was published in the Journal of Occupational and Environmental Medicine.
Study findings
Workers with paid sick leave reported significantly lower perceived risk of COVID-19 exposure than those with unpaid leave or no leave at all.
Higher perceived risk of infection was associated with greater job stress, which in turn predicted lower job satisfaction. Paid sick leave interrupted that chain.
Workers with no access to sick leave experienced both direct and indirect drops in job satisfaction, suggesting compounded harms when workers lack any safety net.
Why it matters
Many home service workers enter multiple private homes each day. When paid sick leave is available only after a documented diagnosis (like a positive test for COVID-19), workers face a high-stakes choice during their most contagious period: lose income or risk exposing others.
The researchers contend that paid sick leave should be treated as a preventive mechanism that allows workers to stay home when symptoms first appear—before diagnosis or transmission. As policymakers revisit pandemic lessons and prepare for future public health emergencies, this study suggests that expanding paid sick leave is not only a worker protection, but a population-level prevention strategy.
Did we just see a black hole explode? UMass Amherst’s physicists think so. This artist's concept takes a fanciful approach to imagining small primordial black holes.
AMHERST, Mass. — In 2023, a subatomic particle called a neutrino crashed into Earth with such a high amount of energy that it should have been impossible. In fact, there are no known sources anywhere in the universe capable of producing such energy—100,000 times more than the highest-energy particle ever produced by the Large Hadron Collider, the world’s most powerful particle accelerator. However, a team of physicists at the University of Massachusetts Amherst recently hypothesized that something like this could happen when a special kind of black hole, called a “quasi-extremal primordial black hole,” explodes.
In new research published byPhysical Review Letters, the team not only accounts for the otherwise impossible neutrino but shows that the elementary particle could reveal the fundamental nature of the universe.
Black holes exist, and we have a good understanding of their life cycle: an old, large star runs out of fuel, implodes in a massively powerful supernova and leaves behind an area of spacetime with such intense gravity that nothing, not even light, can escape. These black holes are incredibly heavy and are essentially stable.
But, as physicist Stephen Hawking pointed out in 1970, another kind of black hole—a primordial black hole (PBH), could be created not by the collapse of a star, but from the universe’s primordial conditions shortly after the Big Bang. PBHs exist only in theory so far, and, like standard black holes, are so massively dense that almost nothing can escape them—which is what makes them “black.” However, despite their density, PBHs could be much lighter than the black holes we have so far observed. Furthermore, Hawking showed that PBHs could slowly emit particles via what is now known as “Hawking radiation” if they got hot enough.
“The lighter a black hole is, the hotter it should be and the more particles it will emit,” says Andrea Thamm, co-author of the new research and assistant professor of physics at UMass Amherst. “As PBHs evaporate, they become ever lighter, and so hotter, emitting even more radiation in a runaway process until explosion. It’s that Hawking radiation that our telescopes can detect.”
If such an explosion were to be observed, it would give us a definitive catalog of all the subatomic particles in existence, including the ones we have observed, such as electrons, quarks and Higgs bosons, the ones that we have only hypothesized, like dark matter particles, as well as everything else that is, so far, entirely unknown to science. The UMass Amherst team has previously shown that such explosions could happen with surprising frequency—every decade or so—and if we were to pay attention, our current cosmos-observing instruments could register these explosions.
So far, so theoretical.
Then, in 2023, an experiment called the KM3NeT Collaboration captured that impossible neutrino—exactly the kind of evidence the UMass Amherst team hypothesized we might soon see.
But there was a hitch: A similar experiment, called IceCube, also set up to capture high-energy cosmic neutrinos, not only didn’t register the event, it had never clocked anything with even one hundredth of its power. If the universe is relatively thick with PBHs, and they are exploding frequently, shouldn’t we be showered in high-energy neutrinos? What can explain the discrepancy?
“We think that PBHs with a ‘dark charge’—what we call quasi-extremal PBHs—are the missing link,” says Joaquim Iguaz Juan, a postdoctoral researcher in physics at UMass Amherst and one of the paper’s co-authors. The dark charge is essentially a copy of the usual electric force as we know it, but which includes a very heavy, hypothesized version of the electron, which the team calls a “dark electron.”
“There are other, simpler models of PBHs out there,” says Michael Baker, co-author and an assistant professor of physics at UMass Amherst; “our dark-charge model is more complex, which means it may provide a more accurate model of reality. What’s so cool is to see that our model can explain this otherwise unexplainable phenomenon.”
“A PBH with a dark charge,” adds Thamm, “has unique properties and behaves in ways that are different from other, simpler PBH models. We have shown that this can provide an explanation of all of the seemingly inconsistent experimental data.
The team is confident that, not only can their dark-charge model PBHs explain the neutrino, it can also answer the mystery of dark matter. “Observations of galaxies and the cosmic microwave background suggest that some kind of dark matter exists,” says Baker.
“If our hypothesized dark charge is true,” adds Iguaz Juan, “then we believe there could be a significant population of PBHs, which would be consistent with other astrophysical observations, and account for all the missing dark matter in the universe.”
“Observing the high-energy neutrino was an incredible event,” Baker concludes. “It gave us a new window on the universe. But we could now be on the cusp of experimentally verifying Hawking radiation, obtaining evidence for both primordial black holes and new particles beyond the Standard Model, and explaining the mystery of dark matter.”
The flagship of the commonwealth, the University of Massachusetts Amherst is a nationally ranked public land-grant research university that seeks to expand educational access, fuel innovation and creativity and share and use its knowledge for the common good. Founded in 1863, UMass Amherst sits on nearly 1,450-acres in scenic Western Massachusetts and boasts state-of-the-art facilities for teaching, research, scholarship and creative activity. The institution advances a diverse, equitable, and inclusive community where everyone feels connected and valued—and thrives, and offers a full range of undergraduate, graduate and professional degrees across 10 schools and colleges and 100 undergraduate majors.
A swarm of small earthquakes within the Karoo Basin in South Africa has revealed a critically stressed fault that could be perturbed by potential shale gas exploration in the area, according to a new report in Seismological Research Letters.
The analysis by Benjamin Whitehead of the University of Cape Town and colleagues concludes that the Karoo microseismicity occurred along a buried fault that may extend through sedimentary layers to the crystalline bedrock, which would increase its vulnerability to stresses produced by shale gas exploration.
Previous research suggests damaging earthquakes can occur even in relatively seismically stable, intraplate regions such as South Africa if regional faults are stressed by hydraulic fracturing, wastewater disposal and other similar techniques used in unconventional oil and gas exploration.
The earthquake swarm near Leeu Gamka is in a part of the southern Karoo Basin undergoing strategic environmental assessment before potential shale gas development. To learn more about this swarm, which began suddenly in 2007, the researchers used data collected from an array of geophones, along with previously collected geophysical data.
“Our local array deployment enabled us to characterize and interpret this seismicity in a more rigorous way, to identify the location and scale of the structure on which the earthquakes occurred, and to determine that this structure was likely to be hydraulically connected to the depths which could be effected by unconventional shale gas development,” said Whitehead.
Although regional networks initially discovered this earthquake cluster (the largest at magnitude 4.8), the new analysis confirmed a depth, direction and extent for the swarm of low magnitude earthquakes. Whitehead and colleagues also showed that the earthquake swarm is associated with a region in the crust where seismic waves abruptly change their velocity, which helped to further delineate the fault structure.
The researchers were able to image Rayleigh wave group velocities using ambient seismic “noise” collected by the array to image seismic structures, even though the array was not configured for this purpose. “I think this is a nice example of successfully reusing data for something it was originally not intended for,” Whitehead explained.
Together, the results “suggest that a critically stressed fault extends from the proposed target for shale gas exploration down to the basement, and so the necessary preconditions for significant induced seismicity may be met,” the authors write.
University of Cape Town researchers continue to deploy geophone arrays to better understand the seismic hazard in South Africa, Whitehead said.
“Interesting questions include whether some of the currently observed clusters of low-magnitude seismicity may be long-lived aftershock sequences for larger earthquakes, associated with the repeated activity on long-lived weak fault zones, or if very ancient stresses are being released and seismicity is likely to migrate to other regions once they are released locally,” he noted.
There are large fault scarps in southern Africa, indicating that large (magnitude 7 or larger) earthquakes may be rare but do occur, he added. “Knowing where and how often these larger events occur can help engineers, regulators and policymakers in the region make more informed decisions.”
The research team has made its data freely available, Whitehead said. “Our group has been involved in this research area for some time and continues to be open to advising regulators and shale gas developers, if development is to proceed.”
This study is part of an upcoming SRL Focus Section on intraplate earthquakes.
An Intraplate Seismic Swarm in the Karoo Basin, South Africa, Highlights the Presence of Critically Stressed Faults in an Area of Proposed Shale Gas Exploration
Human vaginal microbiome is shaped by competition for resources
Credit: Manuel Medina, Flickr (CC0, https://creativecommons.org/publicdomain/zero/1.0/)
The vaginal microbiota is shaped by bacterial access to specific nutritional resources, influencing health outcomes. This study uses a resource-based model supported by clinical data to identify key ecological mechanisms underlying microbiota composition and potential bacterial vaginosis interventions.
In your coverage, please use this URL to provide access to the freely available paper in PLOS Biology: https://plos.io/4qaZ2kt
Article title: Resource landscape shapes the composition and stability of the human vaginal microbiota
Author countries: France, United States
Funding: Research reported in this publication was supported by the Fondation pour la Recherche Medicale (award SPF202005011951 to TK), the Expos’UM institute (to NT) and also in part by the National Institute for Allergy and Infectious Diseases (awards R01NR015495 to JR) and the National Institute of Nursing Research of the National Institutes of Health under (award UH2AI083264 to JR), the Gates Foundation (award OPP1189205 to JR), and the CUPS2 project from the Agence Nationale de la Recherche (award ANR-22-CE34-0024 to SA). The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.
Competing interests: We have read the journal’s policy and the authors of this manuscript have the following competing interests: JR is the cofounder of LUCA Biologics, a biotechnology company focusing on translating microbiome research into live biotherapeutics drugs for women’s health, and a member of Ancilia Bio Scientific Advisory Board. The other authors have declared that no competing interests exist.
