Scientists develop nanosilver-impregnated silk suture against surgical site infection

In recent years, the adherence of microorganisms to surfaces or coatings has created major health risks to humans. Among these, microbial attachment and growth on surgical suture lines accounts for more than 20% of health-related infections in patients.

As a result, extensive research has been conducted to develop strategies for preventing or reducing the formation of bacterial or fungal colonies on sutures.

Nanosilver has gained significant attention among researchers due to its long-known antimicrobial properties. Its optical and structural characteristics make it an appealing candidate for biomedical applications.

It can be synthesized using both green and chemical methods, although it typically carries a negative charge, which can compromise its stability and storage capabilities.

The biological impact of this synthesis was recently published in ACS Omega, where its effectiveness in coating silk sutures and inhibiting the growth of microorganisms was detailed by the research team.

Diego Antonio Monroy Caltzonci et al, Antimicrobial and Cytotoxic Effect of Positively Charged Nanosilver-Coated Silk Sutures, ACS Omega (2024). DOI: 10.1021/acsomega.4c01257

Quantum electronics: Charge travels like light in bilayer graphene

An international research team has demonstrated experimentally that electrons in naturally occurring double-layer graphene move like particles without any mass, in the same way that light travels. Furthermore, they have shown that the current can be "switched" on and off, which has potential for developing tiny, energy-efficient transistors—like the light switch in your house but at a nanoscale.

Graphene was identified in 2004 and is a single layer of carbon atoms. Among its many unusual properties, graphene is known for its extraordinarily high electrical conductivity due to the high and constant velocity of electrons traveling through this material. This unique feature has made scientists dream of using graphene for much faster and more energy-efficient transistors.

The challenge has been that to make a transistor, the material needs to be controlled to have a highly insulating state in addition to its highly conductive state. In graphene, however, such a "switch" in the speed of the carrier cannot be easily achieved. In fact, graphene usually has no insulating state, which has limited graphene's potential a transistor.

A research team has now found that two graphene layers, as found in the naturally occurring form of double-layer graphene, combine the best of both worlds: a structure that supports the amazingly fast motion of electrons moving like light as if they had no mass, in addition to an insulating state. The researchers showed that this condition can be changed by the application of an electric field applied perpendicularly to the material, making the double-layer graphene insulating.

This property of fast-moving electrons had been theoretically predicted as early as 2009, but it took significantly enhanced sample quality as enabled my materials supplied by NIMS and close collaboration about theory with MIT, before it was possible to identify this experimentally. While these experiments were carried out at cryogenic temperatures—at around 273° below freezing—they show the potential of bilayer graphene to make highly efficient transistors.

 Anna M. Seiler et al, Probing the tunable multi-cone band structure in Bernal bilayer graphene, Nature Communications (2024). DOI: 10.1038/s41467-024-47342-0

Pigeons are on par with primates in their numerical abilities, according to new University of Otago research appearing in the leading international journal Science.

The Department of Psychology researchers showed that pigeons can compare pairs of images picturing up to nine objects and order them by the lower to higher number with a success rate above chance.

“Pigeons on par with primates in numerical competence,” by Damian Scarf, Harlene Hayne, Michael Colombo. 23 December 2011, Vol 334, Science DOI: 10.1126/science.1213357

https://phys.org/news/2011-12-monkeys-pigeons.html#:~:text=(PhysOrg.com)%20%2D%2D%20Pigeons,the%20leading%20international%20journal%20Science.

Study reveals how humanity could unite to address global challenges

New research has found that perceptions of globally shared life experiences and globally shared biology can strengthen psychological bonding with humanity at large, which can motivate prosocial action on a global scale and help to tackle global problems. The findings have been published recently in Royal Society Open Science.

Many of the most daunting challenges facing humankind today—from the climate crisis and poverty to food insecurity and terrorism—can only be overcome through cooperation and collective action on a global scale. But what would it take to unite humanity in this way?

According to the results of a new study, the key could lie in two of the most potent drivers of social bonding known in group psychology—shared ancestry and shared transformative experiences—albeit shared not only on the level of the tribe, the nation, or the religious community, but with humanity at large.

Us-vs-them thinking is on the rise in many places all over the world, exacerbating conflicts and complicating finding solutions for pressing global problems. This new research, however, suggests that it is possible to foster a shared global identity which could facilitate cooperation on the global level. The practical implications of our findings for policymakers, NGOs, politicians, and activists are wide-ranging.

In two studies involving more than a thousand US participants in total, the researchers investigated whether shared biology and shared experiences with people across the world can foster bonding with humanity at large and motivate prosocial action on a global scale.

Part 1

To explore whether appeals to our globally shared biology can affect bonding with humanity at large, the study participants watched a TED Talk delivered by journalist A. J. Jacobs explaining how all humans share a common ancestry, portraying us as one large human family.

Those who watched the video expressed significantly stronger psychological bonds with humanity at large compared with a control group whose attitudes were measured before rather than after they had watched the video. Furthermore, participants who watched the video felt stronger social bonds with individuals supporting an opposing political party, compared with the control group.

To investigate whether globally shared experiences can strengthen social bonds on a global scale, the study focused on the common experience of motherhood. The researchers recruited a sample of mothers and showed that mothers felt stronger bonds with other women from all over the world if they shared motherhood experiences with them.

In each case, the strength of social bonds was measured using a series of images of two overlapping circles—one representing the participant and the other one a group, e.g. humanity at large or the group of all the world's mothers. The images differed in the degree of overlap between the two circles. Participants had to choose the image that best represented their relationship with the group, with the images that had the greatest amount of overlap representing the strongest social bonds with the group.

In both studies, the reported psychological bonding on a global scale was strongly reflected in measures of prosocial action. To assess this, the researchers used a measure from behavioral economics, where participants had to indicate how they would split an amount of money between members of two different groups in hypothetical scenarios. This measure is used as a practical and cost-efficient tool in experiments to shed light on how strongly participants care about different groups and has been shown to predict real-stakes behaviour very accurately.
Remembering that we are all related and all experience many of the same challenges in life could be the key to addressing a wide range of global problems, from intergroup conflicts to extreme poverty and the climate crisis, conclude teh researchers.

Why Care for Humanity?, Royal Society Open Science (2024). DOI: 10.1098/rsos.231632. royalsocietypublishing.org/doi/10.1098/rsos.231632

Part 2

Scientists discover how soil microbes survive in harsh desert environments

Prolonged droughts followed by sudden bursts of rainfall—how do desert soil bacteria manage to survive such harsh conditions? This long-debated question has now been answered by an ERC project led by a microbiologist Dagmar Woebken from the Centre for Microbiology and Environmental Systems Science (CeMESS) at the University of Vienna.

The study reveals that desert soil bacteria are highly adapted to survive the rapid environmental changes experienced with each rainfall event. These findings were recently published in the journal Nature Communications.

When scientists simulated a rainfall event in the laboratory, they observed that within the first 15 to 30 minutes, almost all taxonomic groups switched from a resting mode to an active mode. This is a remarkable characteristic of desert soil bacteria, as in other types of soil many groups of bacteria take much longer to reactivate. When reactivated, the bacteria would quickly begin to generate energy and repair their genomes.
In the study, the researchers simulated rainfall events with stable isotope labeled water—water containing heavy hydrogen. Using NanoSIMS, they examined individual cells to see which of them had incorporated the heavy hydrogen atoms.

With this approach, researchers can reveal the fraction of biocrust cells that reactivate in a rain event. We can also infer if they can grow in short rain events that in arid deserts often only last 1 to 2 days.
They found that almost all biocrust cells reactivate, but that in these short rain events only a small proportion of the cells would be able to double. A large proportion of the biocrust cells can therefore use rain events to regenerate and prepare for the next drought, but cell division does not occur.
These data help scientists understand how biocrust bacteria make optimal use of the short activity windows they experience in deserts. They are ideally adapted to withstand short-term changes in soil water content, a very stressful situation for the cells. This allows them to survive the sudden increase in water content during rain, as well as the subsequent drying out.
Additionally, the diverse microbial community is capable of immediate reactivation, which is of great benefit when it must return to a dormant state within a few hours to days.
The findings of this study are relevant not only for desert areas but also for other regions. The ability to survive water limitation will become increasingly important for soil microorganisms in temperate regions, as the frequency and intensity of droughts are increasing due to climate change. Insights gained from desert soil research can help to understand which features make soil microorganisms successful in surviving these challenges.

Survival and rapid resuscitation permit limited productivity in desert microbial communities, Nature Communications (2024). DOI: 10.1038/s41467-024-46920-6

Part 2

Amazon butterflies show how new species can evolve from hybridization

If evolution was originally depicted as a tree, with different species branching off as new blooms, then new research shows how the branches may actually be more entangled. In "Hybrid speciation driven by multilocus introgression of ecological traits," published in Nature,  researchers show that hybrids between species of butterflies can produce new species that are genetically distinct from both parent species and their earlier forebears.

Writing to Charles Darwin in 1861, naturalist Henry Walter Bates described brightly colored Heliconius butterflies of the Amazon as "a glimpse into the laboratory where Nature manufactures her new species." More than 160 years later, an international team of researchers led by biologists Neil Rosser, Fernando Seixas, James Mallet, and Kanchon Dasmahapatra also focused on Heliconius to document the evolution of a new species.
Using whole-genome sequencing, the researchers have shown that a hybridization event some 180,000 years ago between Heliconius melpomene and the ancestor of today's Heliconius pardalinus produced a third hybrid species, Heliconius elevatus. Although descended from hybrids, H. elevatus is a distinct butterfly species with its own individual traits, including its caterpillar's host plant and the adult's male sex pheromones, color pattern, wing shape, flight, and mate choice. All three species now fly together across a vast area of the Amazon rainforest.

Part 1

Historically hybridization was thought of as a bad thing that was not particularly important when it came to evolution. But what genomic data have shown is that actually hybridization among species is widespread.
The implications may alter how we view species. A lot of species are not intact units. They're quite leaky, and they're exchanging genetic material.
So the species that are evolving are constantly exchanging genes, and the consequence of this is that it can actually trigger the evolution of completely new lineages.
Normally, species are thought to be reproductively isolated. They can't produce hybrids that are reproductively fertile. While there is now evidence of hybridization between species, what was difficult to confirm was that this hybridization is, in some way, involved in speciation. The question is: How can you collapse two species together and get a third species out of that collapse.

The new research provides a next step in understanding how hybridization and speciation work. Over the last 10 or 15 years, there's been a paradigm shift in terms of the importance of hybridization and evolution.
This research has the potential to play a role in the current biodiversity crisis. Understanding something as basic as "what we mean by a species is important for saving species and for conservation," particularly in the Amazon.
In addition, such work may prove useful in understanding carriers of disease. Multiple species of mosquito, for example, can carry malaria. Although these mosquitos are closely related, almost nothing is known about how they interact, and whether they hybridize with each other.

Neil Rosser, Hybrid speciation driven by multilocus introgression of ecological traits, Nature (2024). DOI: 10.1038/s41586-024-07263-w. www.nature.com/articles/s41586-024-07263-w

Part 2

Researchers identify a group of cells involved in working memory

Investigators have discovered how brain cells responsible for working memory—the type required to remember a phone number long enough to dial it—coordinate intentional focus and short-term storage of information. The study detailing their discovery was published in Nature.

They have identified for the first time a group of neurons, influenced by two types of brain waves, that coordinate cognitive control and the storage of sensory information in working memory. These neurons don't contain or store information, but are crucial to the storage of short-term memories.

Working memory, which requires the brain to store information for only seconds, is fragile and requires continued focus to be maintained. In disorders such as Alzheimer's disease or attention-deficit hyperactivity disorder, it is often not memory storage, but rather the ability to focus on and retain a memory once it is formed that is the problem,

Understanding the control aspect of working memory will be fundamental for developing new treatments for these and other neurological conditions.
Part 1

**

To explore how working memory functions, investigators recorded the brain activity of 36 hospitalized patients who had electrodes surgically implanted in their brains as part of a procedure to diagnose epilepsy. The team recorded the activity of individual brain cells and brain waves while the patients performed a task that required use of working memory.

On a computer screen, patients were shown either a single photo or a series of three photos of various people, animals, objects or landscapes. Next, the screen went blank for just under three seconds, requiring patients to remember the photos they just saw. They were then shown another photo and asked to decide whether it was the one (or one of the three) they had seen before.

When patients performing the working memory task were able to respond quickly and accurately, investigators noted the firing of two groups of neurons: "category" neurons that fire in response to one of the categories shown in the photos, such as animals, and "phase-amplitude coupling," or PAC, neurons.

PAC neurons, newly identified in this study, don't hold any content, but use a process called phase-amplitude coupling to ensure the category neurons focus and store the content they have acquired.

PAC neurons fire in time with the brain's theta waves, which are associated with focus and control, as well as to gamma waves, which are linked to information processing. This allows them to coordinate their activity with category neurons, which also fire in time to the brain's gamma waves, enhancing patients' ability to recall information stored in working memory.

Imagine when the patient sees a photo of a cat, their category neurons start firing 'cat, cat,cat, cat' while the PAC neurons are firing 'focus/remember'.
Through phase-amplitude coupling, the two groups of neurons create a harmony superimposing their messages, resulting in 'remember cat.' It is a situation where the whole is greater than the sum of its parts, like hearing the musicians in an orchestra play together. The conductor, much like the PAC neurons, coordinates the various players to act in harmony.

PAC neurons do this work in the hippocampus, a part of the brain that has long been known to be important for long-term memory. This study offers the first confirmation that the hippocampus also plays a role in controlling working memory.

Ueli Rutishauser, Control of working memory by phase–amplitude coupling of human hippocampal neurons, Nature (2024). DOI: 10.1038/s41586-024-07309-z. www.nature.com/articles/s41586-024-07309-z

Part 2

Sink to source: Does what we put into our plumbing end up back in the water supply?

When you see an advertisement for a detergent promising to brighten your clothes, something called a fluorescent whitening compound, or optical brightener, is probably involved. Such material absorbs UV light and emits visible blue light via fluorescence. The result? Brighter whites, vibrant colors. Yes, your clothes are glowing.

However, these brighteners can make their way into the water supply!

 When limestone and dolomite dissolve, they can form spectacular caves and sinkholes characteristic of a karst terrain. Karst aquifers can also feature interconnected fractures that create conduits that channel water. These aquifers are a major source of drinking water around the world. Unfortunately, they're also exceptionally vulnerable to pollution. Features that connect Earth's surface directly with an aquifer can funnel pollutants into water supplies.

Researchers have detected high concentrations of fluorescent whitening compounds and microplastics in these waters.

 When fluorescent whitening compounds, which definitely come from humans, and microplastics rise and fall together in water samples, that covariation indicates that microplastic contamination is probably coming from wastewater. Indeed, this is the first study to show such a link in samples from karst springs.

Luka Vucinic et al, Understanding the impacts of human wastewater effluent pollution on karst springs using chemical contamination fingerprinting techniques, EGU General Assembly (2024). DOI: 10.5194/egusphere-egu24-11063

Scientists Discover How Tardigrades Survive Blasts of Radiation

Tardigrades are possibly the most indestructible animal on Earth. These microscopic little beasties can take almost anything humans throw at them, and waddle away perfectly intact.

The strategies behind these feats of superheroic survival are multiple, from a damage suppressor protein that literally protects their DNA, to a dehydrated, suspended animation 'tun' state that they can enter when external conditions get untenable.

And now, scientists have uncovered a new one. They're able to turn up the dial on damage repair to 11.

They blasted tardigrades with gamma rays, and watched to see how they responded.

We've known about tardigrades' fascinating resistance to ionizing radiation for decades. They can survive around 1,000 times the dose that would be lethal to humans, and continue going about their tiny lives as though it were nothing.

The damage suppression protein, Dsup, is thought to play a role in this for some tardigrades, but not all tardigrade species have Dsup or a homolog thereof, suggesting that there is some other means of survival at play.

Part 1

To figure it out, the researchers investigated the effect of gamma radiation on a species of tardigrade called Hypsibius exemplaris. They placed tardigrades in a benchtop irradiator that exposed the critters to gamma rays emitted by the beta decay of cesium-137. Since the amount of radiation is known, they were able to expose the tardigrades to specific doses – one lower dose that is within tolerable levels, and a much higher median lethal dose.

To their surprise, although H. exemplaris does have Dsup, the radiation exposure didn't seem to trigger it. In fact, the tardigrades' DNA took a pretty big whack of radiation damage.

Rather than prophylactic protection, the tardigrades ramped up production of DNA repair genes to such a degree that their products became some of the most abundant in their microscopic bodies. By 24 hours after radiation exposure, the tardigrades had repaired most of the DNA broken by ionizing radiation.
In a follow-up, the researchers expressed some of the tardigrade repair genes in a culture of Escherichia coli, and exposed samples of the bacterium to ionizing radiation. Bacteria that had been inoculated with tardigrade genes showed a similar DNA repair ability to that seen in H. exemplaris, but not seen in untreated E. coli.
This suggests, the researchers found, that H. exemplaris is able to sense ionizing radiation, and mount a response that allows it to survive doses that would obliterate other animals.

These animals are mounting an incredible response to radiation, and that seems to be a secret to their extreme survival abilities.

https://www.cell.com/current-biology/abstract/S0960-9822(24)00316-6

Scientists uncover 95 regions of the genome linked to PTSD

In post-traumatic stress disorder (PTSD), intrusive thoughts, changes in mood, and other symptoms after exposure to trauma can greatly impact a person's quality of life. About 6% of people who experience trauma develop the disorder, but scientists don't yet understand the neurobiology underlying PTSD.

Now, a new genetic study of more than 1.2 million people has pinpointed 95 loci, or locations in the genome, that are associated with risk of developing PTSD, including 80 that had not been previously identified. The study, from the PTSD working group within the Psychiatric Genomics Consortium (PGC—PTSD) together with Cohen Veterans Bioscience, is the largest and most diverse of its kind, and also identified 43 genes that appear to have a role in causing PTSD. The work appears in Nature Genetics.

This discovery firmly validates that heritability is a central feature of PTSD based on the largest PTSD genetics study conducted to date and reinforces there is a genetic component that contributes to the complexity of PTSD.

The findings both confirm previously discovered genetic underpinnings of PTSD and provide many novel targets for future investigation that could lead to new prevention and treatment strategies.

Genome-wide association analyses identify 95 risk loci and provide insights into the neurobiology of post-traumatic stress disorder, Nature Genetics (2024). DOI: 10.1038/s41588-024-01707-9

AI tool predicts responses to cancer therapy using information from each cell of the tumour

With more than 200 types of cancer and every cancer individually unique, ongoing efforts to develop precision oncology treatments remain daunting. Most of the focus has been on developing genetic sequencing assays or analyses to identify mutations in cancer driver genes, then trying to match treatments that may work against those mutations.

But many, if not most, cancer patients do not benefit from these early targeted therapies. In a new study published in the journal Nature Cancer, scientists describe a first-of-its-kind computational pipeline to systematically predict patient response to cancer drugs at single-cell resolution. 

Dubbed PERsonalized Single-Cell Expression-Based Planning for Treatments in Oncology, or PERCEPTION, the new artificial intelligence–based approach dives deeper into the utility of transcriptomics—the study of transcription factors, the messenger RNA molecules expressed by genes that carry and convert DNA information into action.

A tumor is a complex and evolving beast. Using single-cell resolution can allow us to tackle both of these challenges.

PERCEPTION allows for the use of rich information within single-cell omics to understand the clonal architecture of the tumor and monitor the emergence of resistance (In biology, omics refers to the sum of constituents within a cell).

The ability to monitor the emergence of resistance is the most exciting part for researchers. It has the potential to allow them to adapt to the evolution of cancer cells and even modify their treatment strategy.

PERCEPTION: Predicting patient treatment response and resistance via single-cell transcriptomics of their tumors, Nature Cancer (2024). DOI: 10.1038/s43018-024-00756-7

Discovery of new ancient giant snake in India

A new ancient species of snake dubbed Vasuki Indicus, which lived around 47 million years ago in the state of Gujarat in India, may have been one of the largest snakes to have ever lived, suggests new research published in Scientific Reports. The new species, which reached an estimated length of between 11 and 15 meters, was part of the now extinct madtsoiidae snake family, but represented a distinct lineage that originated in India.

Researchers describe a new specimen recovered from the Panandhro Lignite Mine, Kutch, Gujarat State, India, which dates to the Middle Eocene period, approximately 47 million years ago. The new species is named Vasuki indicus after the mythical snake round the neck of the Hindu deity Shiva and in reference to its country of discovery, India. The authors describe 27 mostly well-preserved vertebra, some of which are articulated, which appear to be from a fully-grown animal.

The vertebrae measure between 37.5 and 62.7 millimeters in length and 62.4 and 111.4 millimeters in width, suggesting a broad, cylindrical body. Extrapolating from this, the authors estimate that V. Indicus may have reached between 10.9 and 15.2 meters in length. This is comparable in size to the longest known snake to have ever lived, the extinct Titanoboa, although the authors highlight the uncertainty around these estimates. They further speculate that V. Indicus's large size made it a slow-moving, ambush predator akin to an anaconda.

The authors identify V. Indicus as belonging to the madtsoiidae family, which existed for around 100 million years from the Late Cretaceous to the Late Pleistocene and lived in a broad geographical range including Africa, Europe, and India. They suggest that V. Indicus represents a lineage of large madtsoiids that originated in the Indian subcontinent and spread via southern Europe to Africa during the Eocene, approximately 56 to 34 million years ago.

Debajit Datta, Largest known madtsoiid snake from warm Eocene period of India suggests intercontinental Gondwana dispersal, Scientific Reports (2024). DOI: 10.1038/s41598-024-58377-0. www.nature.com/articles/s41598-024-58377-0

Researchers crack mystery of swirling vortexes in egg cells

Egg cells are the largest single cells on the planet. Their size—often several to hundreds of times the size of a typical cell—allows them to grow into entire organisms, but it also makes it difficult to transport nutrients and other molecules around the cell. Scientists have long known that maturing egg cells, called oocytes, generate internal, twister-like fluid flows to transport nutrients, but how those flows arise in the first place has been a mystery.

Now, research led by computational scientists, has revealed that these flows—which look like microscopic tornados—arise organically from the interactions of a few cellular components.

Their work, published in Nature Physics, used theory, advanced computer modeling, and experiments with fruit fly egg cells to uncover the twisters' mechanics. The results are helping scientists better understand foundational questions about egg cell development and cellular transport.

In a typical human cell, it takes only 10 to 15 seconds for a typical protein molecule to meander from one side of the cell to the other via diffusion; in a small bacterial cell, this trip can happen in just a single second. But in the fruit fly egg cells studied here, diffusion alone would take an entire day—much too long for the cell to function properly. Instead, these egg cells have developed 'twister flows' that circle around the interior of the oocyte to distribute proteins and nutrients quickly, just as a tornado can pick up and move material much farther and quicker than wind alone. 

Sayantan Dutta et al, Self-organized intracellular twisters, Nature Physics (2024). DOI: 10.1038/s41567-023-02372-1

Why zebrafish can regenerate damaged heart tissue, while other fish species cannot

A heart attack will leave a permanent scar on a human heart, yet other animals, including some fish and amphibians, can clear cardiac scar tissue and regrow damaged muscle as adults.

Scientists have sought to figure out how special power works in hopes of advancing medical treatments for human cardiac patients, but the great physiological differences between fish and mammals make such inquiries difficult.

So biologists tackled the problem by comparing two fish species: zebra fish, which can regenerate its heart, and medaka, which cannot.

By comparing these two fish that have similar heart morphology and live in similar habitats, researchers could have a better chance of actually finding what the main differences are.

They  identified a few possible explanations, mostly associated with the immune system, for how zebrafish fix cardiac tissue, according to research published in Biology Open.

Their study shed new light on the molecular and cellular mechanisms at play in zebrafish's heart regeneration. It told them these two hearts that look very similar are actually very different.

Both members of the teleost family of ray-finned fish, zebrafish (Danio rerio) and medaka (Oryzias latipes) descended from a common ancestor that lived millions of years ago. Both are about 1.5 inches long, inhabit freshwater and are equipped with two-chamber hearts. Medaka are native to Japan and zebrafish are native to the Ganges River basin.

According to the study, the existence of non-regenerating fish presents an opportunity to contrast the differing responses to injury to identify the cellular features unique to regenerating species. The research team suspect heart regeneration is an ancestral trait common to all teleosts.

Understanding the evolutionary path that led to the loss of this ability in some teleost species could offer parallel insights into why mammals cannot regenerate as adults.

part 1

To conduct their experiments, the  researchers used a device called a cryoprobe to injure the fish hearts in ways that mimic heart attacks in humans, then extracted the hearts after certain time frames to learn how the two species responded differently.

They found that Zebrafish have this immune response that is typical of what you might see during a viral infection, called an interferon response. That response is completely absent in medaka.

The study documented differences in immune cell recruitment and behavior, epicardial and endothelial cell signaling, and alterations in the structure and makeup of the heart. For example, medaka lack a certain type of muscle cells that are present in zebrafish.

The study indicates the zebrafish's ability to regenerate has something to do with its immune system, but understanding exactly how would take more research. For example, far more macrophages, specialized immune cells, migrated into the wound site in zebrafish than in medaka.

Unlike medaka, the zebrafish form a transient scar that doesn't calcify into rigid tissue.

What you do with that scar is what matters. Researchers think that the interferon response causes these specialized macrophage cells to come into that wound site and start to promote the growth of new blood vessels.

Over time new muscle replaces the damaged cardiac tissue and the heart heals.

The scientists' hope is that they build this knowledge base in animals that are really accessible and can be studied in incredible detail, then use that knowledge to generate more focused experiments in mammals, and then maybe someday in human patients.

Clayton M. Carey et al, Distinct features of the regenerating heart uncovered through comparative single-cell profiling, Biology Open (2024). DOI: 10.1242/bio.060156

Part 2

Keys, wallet, phone: the neuroscience behind working memory

Working memory is a fundamental process that allows us to temporarily store important information, such as the name of a person we’ve just met. However distractions can easily interrupt this process, leading to these memories vanishing. By looking at the brain activity of people doing working-memory tasks, a team have now confirmed that working memory requires two brain regions: one to hold a memory as long as you focus on it; and another to control its maintenance by helping you to not get distracted.

Some Microbes Are Tiny 'Vampires' With a Deadly Attraction to Human Blood
Researchers have discovered what they describe as 'bacterial vampirism', identifying particular types of bacteria that are attracted to human blood – an attraction that can lead to fatal infections.
Researchers outline how these deadly bacteria are drawn to serum – the liquid part of our blood – because of the nutrients and energy it provides.

That can be a particular problem for people with irritable bowel disease (IBD), where intestinal bleeding can offer gut bacteria a route into the bloodstream. However, these findings also shed light on potential new treatment routes.
Bacteria infecting the bloodstream can be lethal. Some of the bacteria that most commonly cause bloodstream infections actually sense a chemical in human blood and swim toward it.
The researchers used a customized device for injecting tiny amounts of fluid and a high-powered microscope to analyze the interaction of bacteria and blood.

Strains of three bacteria known to cause fatal infections, belonging to the species Salmonella enterica, Escherichia coli, and Citrobacter koseri, were found to be attracted to the human serum.

What's more, the team identified some of the biological interactions: it looks as though the amino acid serine is one of the chemicals the bacteria can sense, seek out, and consume, via particular protein receptors.
Part 1

This response doesn't take long at all either. In the experiments run for the study, it took less than a minute for these types of bacteria to realize that blood was nearby and to head towards it.

"We show here that the bacterial attraction response to serum is robust and rapid," write the researchers in their published paper.

The types of bacteria investigated here, from the family Enterobacteriaceae, have already been linked to conditions such as gastrointestinal bleeding and sepsis, particularly where IBD is involved.
The thinking is that these bacteria are latching on to the internal bleeding that often comes with IBD, which is how fatalities can occur.
Knowing more about how bacteria sense the serum in blood, and make use of it, might eventually save lives if treatments are focused on this. By learning how these bacteria are able to detect sources of blood, in the future we could develop new drugs that block this ability.
Bacterial vampirism mediated through taxis to serum:

https://elifesciences.org/reviewed-preprints/93178v2

Researchers find lower grades given to students with surnames that come later in alphabetical order

Knowing your ABCs is essential to academic success, but having a last name starting with A, B or C might also help make the grade.

What's in a name? A lot!

An analysis by  researchers of more than 30 million grading records from U-M finds students with alphabetically lower-ranked names receive lower grades. This is due to sequential grading biases and the default order of students' submissions in Canvas—the most widely used online learning management system—which is based on the alphabetical rank of their surnames. What's more, they find, those alphabetically disadvantaged students receive comments that are notably more negative and less polite, and exhibit lower grading quality measured by post-grade complaints from students.

 Researchers suspect that fatigue is one of the major factors that is driving this effect, because when you're working on something for a long period of time, you get tired and then you start to lose your attention and your cognitive abilities  are dropping.

The researchers note the option exists to grade the assignments in a random order, and some educators do, but alphabetical order is the default mode in Canvas and other online learning management systems. One simple fix would be to make random order the default setting.

They also suggest academic institutions could hire more graders for larger classes, distribute the workload among more people or train them to be aware of and lessen the bias while grading.

The study is under review by the journal Management Science and currently available as a working paper.

Researchers find lower grades given to students with surnames that come later in alphabetical order

(This title is somewhat misleading, please read on to know why)

Knowing your ABCs is essential to academic success, but having a last name starting with A, B or C might also help make the grade.

What's in a name? A lot!

An analysis by researchers of more than 30 million grading records from U-M finds students with alphabetically lower-ranked names receive lower grades. This is due to sequential grading biases and the default order of students' submissions in Canvas—the most widely used online learning management system—which is based on the alphabetical rank of their surnames. What's more, they find, those alphabetically disadvantaged students receive comments that are notably more negative and less polite, and exhibit lower grading quality measured by post-grade complaints from students.

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Their research uncovered a clear pattern of a decline in grading quality as graders evaluate more assignments. According to Wang, students whose surnames start with A, B, C, D or E received a 0.3-point higher grade out of 100 possible points than compared to when they were graded randomly. Likewise, students with later-in-the-alphabet surnames received a 0.3-point lower grade—creating a 0.6-point gap.

A 0.6-point difference might seem small, but such a disparity did affect students' course grade-point averages, which negatively influences opportunities in their respective career paths.

The Researchers suspect that fatigue among the examiners is one of the major factors that is driving this effect, because when you're working on something for a long period of time, you get tired and then you start to lose your attention and your cognitive abilities are dropping.

The researchers note the option exists to grade the assignments in a random order, and some educators do, but alphabetical order is the default mode in Canvas and other online learning management systems. One simple fix would be to make random order the default setting.

They also suggest academic institutions could hire more graders for larger classes, distribute the workload among more people or train them to be aware of and lessen the bias while grading.

The study is under review by the journal Management Science and currently available as a working paper.

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(PS: Please take this work with a pinch of salt because we are waiting for reproduction of these results.

This is still under review and the point difference is small.

And, students, this is not an excuse for your laziness. Because this need not be the case every time you write your exams. Most of the time in my practical and viva part of exams I was the last person to submit my results and got interviewed but still got top ranks).

Zhihan (Helen) Wang et al, 30 Million Canvas Grading Records Reveal Widespread Sequential Bias and System-Induced Surname Initial Disparity (2023). On SSRN: ssrn.com/abstract=4603146

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Persistent questioning of knowledge takes a toll: New study supports theories that baseless discrediting harms

It can be demoralizing for a person to work in a climate of repetitive skepticism and doubt about what they know, a new study shows.

This is  not about healthy, well-founded skepticism. This is about failures-of-exchange when a person is persistently overlooked, unheard, brushed off and explained to. 

Why? Something about who the person is—their identity—suggests to their interlocuter that they couldn't possibly be right due to the interlocuter's bias. These biases take many forms: race or ethnicity, manner of speaking, weight, attractiveness, age, style and so on.

Researchers have theorized that baseless discrediting of what people with marginalized social identities know is a central driver of prejudice and discrimination.

They conducted experiments that backed up these theories, finding that people are emotionally invested in being treated as credible, even in anonymous games. Further, they found that emotional impact of discreditation varies based on gender, race and experience with racial discrimination. 

The authors think that hostility in intellectual arenas is an ethical issue.

Discrediting of a person as a legitimate knower can be subtle, which makes it difficult to isolate, and, therefore, understudied.

But growing research shows regular exposure to even relatively subtle prejudice and discrimination degrades physical and mental health, leading to outcomes like high blood pressure, chronic stress and depression.

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To deepen their understanding of the impact of epistemic injustice—injustice around the domain of knowledge—the researchers focused on the emotional consequences of feedback. They modeled epistemic injustice in the lab by creating an experiment to safely simulate everyday experiences of invalidation. Participants observed a game, then shared their knowledge about the game—either how it worked or how they felt about it.

The crucial part of the experiment came next; participants received feedback, supposedly from their partner in the game, about what they shared. Some feedback was validating, some was discrediting, and some was mildly insulting.

The participants then rated how positive or negative that feedback made them feel, the key measure of their emotional responses. The researchers combined the experiment with surveys of variables thought to factor into epistemic injustice—race, gender and experiences with race-based discrimination and trauma.

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The experiment conducted by researchers revealed an important generality about knowledge. People find it more emotionally taxing to have their understanding of facts questioned than to have their feelings questioned.

But more important findings came from the experiment outcomes combined with the surveys, which showed that race and gender factored into the experimental results.

These findings are consistent, with research on prejudice and discrimination showing that Black men experience more racial discrimination in areas where credibility is extremely important—such as employment, educational settings and interactions with law enforcement—but where credibility can be undermined by emotional responses.

Another consistent finding underscored the importance of individual differences. Validation—when participants were told that they were right—was significantly more positive for white women compared with white men, which resonates with studies showing that positive interventions boost women's academic performance.

Insights from this study could benefit managers, educators and people interested in living and working in safer and more just communities. For universities, we think the results highlight the world of emotional coping mechanisms spoken about too rarely, but always under the surface in intellectual spaces.

Laura Niemi et al, The emotional impact of baseless discrediting of knowledge: An empirical investigation of epistemic injustice, Acta Psychologica (2024). DOI: 10.1016/j.actpsy.2024.104157

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Physicists Say The Ultimate Battery Could Harness The Power of Black Holes

In theory, oppositely charged micro black holes could then be brought together, one by one, leading them to merge into a single black hole that 'evaporates' very quickly into pure energy. The extracted energy wouldn't come from within the black hole, but just outside it: where gravity concentrates.
This mind-bending suggestion is not beyond the realms of possibility. Tiny, primordial black holes are thought to exist, but have never been detected – perhaps because they have radiated away most of their energy after forming in the primeval plasma that filled the Universe following the Big Bang.
But the prospect of 'micro black hole batteries' will more than likely remain purely hypothetical, saying more about how far trends in battery technology have to go than where we'll actually end up.

"Today's batteries are extremely inefficient compared to their ultimate potential, and we are likely just at the very beginning of a battery revolution," Espen Haug, a theoretical physicist and finance analyst at the Norwegian University of Life Sciences, and Gianfranco Spavieri, a physicist at the University of the Andes Venezuela, write in their published paper.
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Haug and Spavieri estimate that a micro black hole battery weighing just one kilogram could provide "enough energy for a family for generations" – approximately 470 million times the energy of the most efficient 200-kilogram lithium battery that currently exists.

"While achieving such a level of technological advancement is certainly not imminent, it's not inconceivable that battery technology development could follow a trajectory similar to that of computer technology," Haug and Spavieri write.
The pair aren't the first team to suggest such a wild idea, which just goes to show the gravity (pun intended) of the energy transition we face, to power the world without burning fossil fuels that are cooking the planet.

Previous work has considered similarly small Schwarzschild black holes, but Haug and Spavieri reason the charged black holes described by the Reissner–Nordström metric are eight times more energy-dense.

Of course, whether such tiny, non-rotating black holes exist, or even be created in a practical setting, is a project for future imaginations.

"If we use strategically placed neutron stars as magnets, this would still require [a particle] accelerator around the size of the Solar System," Haug and Spavieri note. "This solution seems quite unrealistic, but never say never."

https://www.sciencedirect.com/science/article/pii/S1574181824000247...

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Crucial building blocks of life on Earth can more easily form in outer space, says new research

The origin of life on Earth is still enigmatic, but we are slowly unraveling the steps involved and the necessary ingredients. Scientists think life arose in a primordial soup of organic chemicals and biomolecules on the early Earth, eventually leading to actual organisms.

It's long been suspected that some of these ingredients may have been delivered from space. Now a new study, published in Science Advances, shows that a special group of molecules, known as peptides, can form more easily under the conditions of space than those found on Earth. That means they could have been delivered to the early Earth by meteorites or comets—and that life may be able to form elsewhere, too.

DNA, or deoxyribonucleic acid, comprises two long strands forming a double helix structure. Each strand is composed of smaller molecules called nucleotides. Every nucleotide contains three components: a sugar molecule (deoxyribose in DNA), a phosphate group, and a nitrogenous base. There are four types of nitrogenous bases in DNA: adenine (A), thymine (T), cytosine (C), and guanine (G). These bases pair specifically (A with T, C with G) to form the rungs of the double helix ladder, with the sugar and phosphate groups forming the backbone of the DNA molecule.

Peptides are an assemblage of amino acids in a short chain-like structure. Peptides can be made up of as little as two amino acids, but also range to hundreds of amino acids.

The assemblage of amino acids into peptides is an important step because peptides provide functions such as "catalyzing," or enhancing, reactions that are important to maintaining life. They are also candidate molecules that could have been further assembled into early versions of membranes, confining functional molecules in cell-like structures.

However, despite their potentially important role in the origin of life, it was not so straightforward for peptides to form spontaneously under the environmental conditions on the early Earth. In fact, the scientists behind the current study had previously shown that the cold conditions of space are actually more favourable to the formation of peptides.

In the very low density of clouds of molecules and dust particles in a part of space called the interstellar medium, single atoms of carbon can stick to the surface of dust grains together with carbon monoxide and ammonia molecules. They then react to form amino acid-like molecules. When such a cloud becomes denser and dust particles also start to stick together, these molecules can assemble into peptides.
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In their new study, the scientists look at the dense environment of dusty disks, from which a new solar system with a star and planets emerges eventually. Such disks form when clouds suddenly collapse under the force of gravity. In this environment, water molecules are much more prevalent—forming ice on the surface of any growing agglomerates of particles that could inhibit the reactions that form peptides.

By emulating the reactions likely to occur in the interstellar medium in the laboratory, the study shows that, although the formation of peptides is slightly diminished, it is not prevented. Instead, as rocks and dust combine to form larger bodies such as asteroids and comets, these bodies heat up and allow for liquids to form. This boosts peptide formation in these liquids, and there's a natural selection of further reactions resulting in even more complex organic molecules. These processes would have occurred during the formation of our own solar system.

Many of the building blocks of life such as amino acids, lipids and sugars can form in the space environment. Many have been detected in meteorites.

Because peptide formation is more efficient in space than on Earth, and because they can accumulate in comets, their impacts on the early Earth might have delivered loads that boosted the steps towards the origin of life on Earth.
So what does all this mean for our chances of finding alien life? Well, the building blocks for life are available throughout the universe. How specific the conditions need to be to enable them to self-assemble into living organisms is still an open question. Once we know that, we'll have a good idea of how widespread, or not, life might be.

Serge A. Krasnokutski et al, Formation of extraterrestrial peptides and their derivatives, Science Advances (2024). DOI: 10.1126/sciadv.adj7179

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When one vulnerable species stalks another

What can be done when one threatened animal kills another? Scientists studying critically endangered lemurs in Madagascar confronted this difficult reality when they witnessed attacks on lemurs by another vulnerable species, a carnivore called a fosa.

This dynamic can be particularly complex when the predation occurs in an isolated or poor-quality habitat, according to research by scientists  in Madagascar.

In the new paper published in Ecology and Evolution, researchers describe how they were observing small groups of critically endangered diademed sifaka lemurs (Propithecus diadema) at Betampona Strict Nature Reserve when the predator struck.

"We were conducting our daily behavioural observations when we came across a very unusual sight—a predation attempt by a fosa, which is the biggest predator in Madagascar", the researchers depicted the story.

"What we saw was very rare," they wrote in their paper. "There are other small carnivores in Madagascar, but they are not big enough to be able to prey upon an adult diademed sifaka because they are among the biggest lemurs. There are not so many predators that could actually get them."

With slender bodies and long tails, fosas (or fossas, Crytoprocta ferox) have many cat-like features. They are great climbers and are sometimes compared to small cougars, though they are actually part of the weasel family.

The fosa is categorized as vulnerable by the International Union for Conservation of Nature and Natural Resources, and is at risk of extinction, as are almost all of its lemur prey. Fosas also eat other small animals such as birds and rodents.

But they're rarely caught in the act. Fosas are stealthy hunters. Researchers have mostly determined what fosas eat by examining bones and other evidence left behind in scat.

"We noticed that a female diademed sifaka that we were following after the first attack didn't run away very far," they said. "Instead she stayed still and remained vigilant, looking at the fosa."

 also documented the later discovery of the remains of another diademed sifaka, presumed to have been killed by a fosa because of the condition of the remains and because of the way that branches had been broken in the area. Signs indicated a struggle in the trees.

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The researchers also described other instances over a period of 19 months of observation when fosas appeared to stalk lemurs but were unsuccessful in bringing one down as food.

The impact of predation—combined with low reproductive rates and potentially high inbreeding of the lemur population of Betampona—could affect the survival of this species at this site, researchers said.

These most recent observations of fosa attacks are especially troubling, as the observation of predation attacks, especially by the elusive fosa, are very rare.

"It leads to questions of why the fosa are so bold to predate on lemurs in front of humans, and whether the fosa leave Betampona to hunt elsewhere and then return, or whether they are targeting the lemurs within the reserve,"the researchers say. "It is an incredible scenario in which you have a vulnerable species potentially over-predating on several critically endangered species."

G. Bonadonna et al, Response of diademed sifaka (Propithecus diadema) to fosa (Cryptoprocta ferox) predation in the Betampona Strict Nature Reserve, Madagascar, Ecology and Evolution (2024). DOI: 10.1002/ece3.11248

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Electron videography captures moving dance between proteins and lipids

In a first demonstration of "electron videography," researchers have captured a microscopic moving picture of the delicate dance between proteins and lipids found in cell membranes. The technique can be used to study the dynamics of other biomolecules, breaking free of constraints that have limited microscopy to still images of fixed molecules.

Scientists are now  are going beyond taking single snapshots, which gives structure but not dynamics, to continually recording the molecules in water, their native state.

They can really see how proteins change their configuration and, in this case, how the whole protein-lipid self-assembled structure fluctuates over time.

The researchers reported their technique and findings in the journal Science Advances.

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Electron microscopy techniques image at the molecular or atomic scale, yielding detailed, nanometer-scale pictures. However, they often rely on samples that have been frozen or fixed in place, leaving scientists to try to infer how molecules move and interact—like trying to map the choreography of a dance sequence from a single frame of film.

Usually, researchers have to crystalize or freeze a protein, which poses challenges in capturing high-resolution images of flexible proteins. Alternately, some techniques use a molecular tag that they track, rather than watching the protein itself. In this study they are seeing the protein as it is, behaving how it does in a liquid environment, and seeing how lipids and proteins interact with each other.

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The researchers achieved videography by combining a novel water-based transmission electron microscopy method with detailed, atom-level computational modeling. The water-based technique involves encapsulating nanometer-scale droplets in graphene so they can withstand the vacuum in which the microscope operates. Comparing the resulting video data to molecular models, which show how things should move based on the laws of physics, helps the researchers not only interpret but also validate their experimental data.
Currently, this is really the only experimental way to film this kind of motion over time. Life is in liquid, and it's in motion. Scientists 're trying to get to the finest details of that connection in an experimental way.
For the new study—the first published demonstration of the electron videography technique—the researchers examined nanoscale discs of lipid membranes and how they interacted with proteins normally found on the surface of or embedded in cell membranes.
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The researchers now plan to use their electron videography technique to study other types of membrane proteins and other classes of molecules and nanomaterials.

 John W. Smith et al, Electron videography of a lipid–protein tango, Science Advances (2024). DOI: 10.1126/sciadv.adk0217

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New models of Big Bang show that visible universe and invisible dark matter co-evolved

Physicists have long theorized that our universe may not be limited to what we can see. By observing gravitational forces on other galaxies, they've hypothesized the existence of "dark matter," which would be invisible to conventional forms of observation.

95% of the universe is dark, is invisible to the eye. 

However, we know that the dark universe is there by its gravitational pull on stars. Other than its gravity, dark matter has never seemed to have much effect on the visible universe.

Yet the relationship between these visible and invisible domains, especially as the universe first formed, has remained an open question.

Now, physicists say that there is mounting evidence that these two supposedly distinct realms actually co-evolved.

Through a series of computer models, physicists have discovered that the visible and the hidden sectors, as they call them, likely co-evolved in the moments after the Big Bang, with profound repercussions for how the universe developed thereafter.

They say there was a time when some physicists effectively wrote off this hidden sector, as they can explain most of what happens within the visible—that is, if our models can accurately portray what we can see happening around us, why bother trying to measure something that has no discernible effect?

The question is, what's the influence of the hidden sector on the visible sector?"  "But what do we care? We can explain everything."

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But we can't explain everything, the authors of this study contends. There are anomalies that don't seem to fit the so-called "Standard Model" of the universe.

That the visible and hidden sectors are mutually isolated is a misconception, they say, based on an assumption "that the visible and the hidden sectors evolved independently of each other." The new work wants to turn that assumption on its head.

In a paper published in Physical Review D, "Big Bang Initial Conditions and Self-Interacting Hidden Dark Matter, they want to ask what they call "the more important question: How do we know that they evolved independently?"

One major variable is the temperature of the hidden sector during the Big Bang.

The visible sector, we can be fairly certain, started out very hot at the moment of the Big Bang. As the universe cools, Nath says, "what we see is the remnant of that period of the universe."

But by studying the evolution of the two sectors, Nath and his team could model both conditions—a hidden sector that started out hot, and another hidden sector that started out cold.

What they observed was surprising: Despite significant differences between the models, with major implications on what the universe looked like in early times, both the hot and cold models were consistent with the visible sector we can observe today.
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Our current measurements of the visible universe, in other words, are insufficient to confirm which side the hidden sector fell on at the beginning—hot or cold.

Nath is quick to point out that, rather than a failing of the experiment, this is an example of the mathematical models outrunning our current experimental capabilities.

It's not that the difference between a hot or cold hidden sector has no bearing on the visible universe, but that we haven't performed experiments—yet—with high enough precision. Nath mentions the Webb Telescope as one example of the next generation of tools that will be able to make such precise observations.

The ultimate goal of all this modeling work is to make better predictions about the state of the universe, how it all functions and what we'll find when we look deeper and deeper into the night sky.

As our experiments gain more accuracy, the questions baked into Nath's models—was the hidden sector hot or cold?—will find their answers, and those clarified models will help predict the solutions to ever-deeper questions.
"What's the significance of this?" Nath asks. Human beings, he says, "want to find their place in the universe." And more than that, "they want to answer the question, why is there a universe?

"And we are exploring those issues. It is the ultimate quest of human beings."

Jinzheng Li et al, Big bang initial conditions and self-interacting hidden dark matter, Physical Review D (2023). DOI: 10.1103/PhysRevD.108.115008

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Study suggests that living near green spaces reduces the risk of depression and anxiety

Over the past decades, a growing number of people have migrated to urban areas, while the size and population of rural areas have drastically declined. While parks and other green spaces are often viewed as beneficial for the well-being of those living in cities and urban regions, so far very few studies have explored the impact of these spaces on mental health.

Researchers recently carried out a study investigating the potential link between long-term exposure to green spaces in proximity of one's home and two of the most common mental health disorders: depression and anxiety. Their findings, published in Nature Mental Health, suggest that living close to parks and green areas can reduce the risk of becoming depressed and experiencing anxiety.

As part of their study, the researchers analyzed data gathered from 409,556 people and stored in the UK Biobank database. They specifically looked at the distance between participants and green areas, in conjunction with their self-reported well-being scores, as well as hospitalizations, hospital admissions, and deaths in their residential area.

The results of the analyses suggest that there is a link between prolonged proximity to residential green areas and the incidence of both depression and anxiety. Specifically, they suggest that living closer to parks and other green areas reduces the risk of experiencing both depression and anxiety.

Researchers draw the important conclusion that long-term exposure to residential greenness is associated with a decreased risk of incident depression and anxiety, and reduced air pollution in the greenest areas probably plays an important role in this trend. This  study thus implies that expanding urban green spaces could promote good mental health.

Jianing Wang et al, Long-term exposure to residential greenness and decreased risk of depression and anxiety, Nature Mental Health (2024). DOI: 10.1038/s44220-024-00227-z.

How light can vaporize water without the need for heat

It's the most fundamental of processes—the evaporation of water from the surfaces of oceans and lakes, the burning off of fog in the morning sun, and the drying of briny ponds that leaves solid salt behind. Evaporation is all around us, and humans have been observing it and making use of it for as long as we have existed.

And yet, it turns out, we've been missing a major part of the picture all along.

In a series of painstakingly precise experiments, a team of researchers  has demonstrated that heat isn't alone in causing water to evaporate. Light, striking the water's surface where air and water meet, can break water molecules away and float them into the air, causing evaporation in the absence of any source of heat.

The astonishing new discovery could have a wide range of significant implications. It could help explain mysterious measurements over the years of how sunlight affects clouds, and therefore affect calculations of the effects of climate change on cloud cover and precipitation. It could also lead to new ways of designing industrial processes such as solar-powered desalination or drying of materials.

The findings, and the many different lines of evidence that demonstrate the reality of the phenomenon and the details of how it works, are described recently in the Proceedings of the National Academy of Sciences.

The authors say their study suggests that the effect should happen widely in nature—everywhere from clouds to fogs to the surfaces of oceans, soils, and plants—and that it could also lead to new practical applications, including in energy and clean water production.

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The new work builds on research reported* last year, which described this new "photomolecular effect" but only under very specialized conditions: on the surface of specially prepared hydrogels soaked with water. In the new study, the researchers demonstrate that the hydrogel is not necessary for the process; it occurs at any water surface exposed to light, whether it's a flat surface like a body of water or a curved surface like a droplet of cloud vapour.

* Yaodong Tu et al, Plausible photomolecular effect leading to water evaporation exceeding the thermal limit, Proceedings of the National Academy of Sciences (2023). DOI: 10.1073/pnas.2312751120

researchers have proposed a physical mechanism that can explain the angle and polarization dependence of the effect, showing that the photons of light can impart a net force on water molecules at the water surface that is sufficient to knock them loose from the body of water. But they cannot yet account for the color dependence, which they say will require further study.

They have named this the photomolecular effect, by analogy with the photoelectric effect that was discovered by Heinrich Hertz in 1887 and finally explained by Albert Einstein in 1905. That effect was one of the first demonstrations that light also has particle characteristics, which had major implications in physics and led to a wide variety of applications, including LEDs. Just as the photoelectric effect liberates electrons from atoms in a material in response to being hit by a photon of light, the photomolecular effect shows that photons can liberate entire molecules from a liquid surface, the researchers say.

The finding of evaporation caused by light instead of heat provides new disruptive knowledge of light-water interaction.
It could help us gain new understanding of how sunlight interacts with cloud, fog, oceans, and other natural water bodies to affect weather and climate. It has significant potential practical applications such as high-performance water desalination driven by solar energy.
The finding may solve an 80-year-old mystery in climate science. Measurements of how clouds absorb sunlight have often shown that they are absorbing more sunlight than conventional physics dictates possible. The additional evaporation caused by this effect could account for the longstanding discrepancy, which has been a subject of dispute since such measurements are difficult to make.

Those experiments are based on satellite data and flight data. They fly an airplane on top of and below the clouds, and there are also data based on the ocean temperature and radiation balance. And they all conclude that there is more absorption by clouds than theory could calculate. However, due to the complexity of clouds and the difficulties of making such measurements, researchers have been debating whether such discrepancies are real or not. And what was discovered now suggests that hey, there's another mechanism for cloud absorption, which was not accounted for, and this mechanism might explain the discrepancies.
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There are many lines of evidence. The flat region in the air-side temperature distribution above hot water will be the easiest for people to reproduce. That temperature profile "is a signature" that demonstrates the effect clearly.
It is quite hard to explain how this kind of flat temperature profile comes about without invoking some other mechanism" beyond the accepted theories of thermal evaporation.
The observations in the manuscript points to a new physical mechanism that foundationally alters our thinking on the kinetics of evaporation.

Guangxin Lv et al, Photomolecular effect: Visible light interaction with air–water interface, Proceedings of the National Academy of Sciences (2024). DOI: 10.1073/pnas.2320844121

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