Comment

Comment by Dr. Krishna Kumari Challa yesterday

Physicists Find a Way to 'Split' Particles of Light in Half to Make Infinite Photons

An elementary particle such as a photon cannot be cut in two pieces. Still it must be possible to truncate a photon with an optical shutter. The result is neither another photon nor a mix of a photon and a vacuum. Instead it is a superposition and mix of photon numbers up to infinity. This state is rather complicated, but nevertheless locally equivalent to a single photon or vacuum to the left and right, respectively, of a narrow transition region.

https://journals.aps.org/prl/abstract/10.1103/94pm-hp34

Comment by Dr. Krishna Kumari Challa yesterday

Where You Carry Your Body Fat Is Directly Linked to Brain Aging

You can weigh the same as someone else, have the same BMI, and still be carrying a completely different risk to your brain.

That's the message from a growing pile of research over the past year.

Scientists have long known that obesity is linked to an increased risk of dementia

But new research suggests that it's not just how much fat you carry, it's where you carry it.

In May, a study linked visceral fat – the kind that packs in around your organs – to faster brain aging. They indicated that glucose and insulin were the likely mechanisms involved.
Researchers mapped fat distribution against brain scans and cognition scores of more than 18,000 people in the UK Biobank dataset.
According to the researchers, it's the world's first large-scale multimodal study to systematically explore the link between where fat is located and brain structure, connectivity, and cognitive performance.

What they found is that where you carry your fat is strongly associated with how fast (or slow) your brain appears to age.

Fat in different parts of the body maps out entirely different trajectories of change in the brain, which cannot be detected by body weight or BMI alone.
Their analytical model clearly demonstrates how fat in different regions causes differential damage to brain systems.
Fat in the arms, legs, trunk, and visceral cavity was each linked to distinct changes across separate brain systems – including regions tied to movement, emotion, memory, and the brainstem.
But the key message from the research is that visceral fat was the only type of fat directly linked to damage to the brain's white matter – the wiring that carries signals between neurons.

White matter damage is closely tied to the biology behind vascular cognitive impairment and small vessel disease in the brain – conditions that sit upstream of dementia risk.

While the study didn't look directly at what could be causing this link, the researchers think chronic, low-grade inflammation triggered by visceral fat may be spilling over into the brain itself, fuelling neuroinflammation.
In contrast, adiposity in the arms, trunk, and legs exhibits lower levels of inflammatory factor secretion.

Reducing visceral fat through targeted lifestyle interventions can open up new pathways for the proactive prevention and treatment of neurodegenerative diseases.

https://www.nature.com/articles/s44220-025-00501-8

Comment by Dr. Krishna Kumari Challa on Thursday

New rule explains why growing shapes suddenly crumple Scientists have discovered a previously unknown law of geometry that explains why some growing surfaces, whether in nature or in engineered materials, suddenly stop being able to stay smooth and instead form dimples and folds. A new geometric law defines a curvature threshold beyond which growing free-standing surfaces cannot remain smooth and must buckle into ordered dimples and folds. This “geometric frustration” is topological, depending on global shape and connectivity, and arises even when previous compatibility rules are satisfied. A single cut can remove the frustration, enabling smooth shapes and informing control of morphogenesis and shape-programmable materials.

Comment by Dr. Krishna Kumari Challa on Thursday

Mapping practice in the brain
To test this hypothesis, researchers conducted a long-term study to track how the brain changes as a task moves toward automaticity. Over the course of 5–10 weeks, 11 participants practiced the car-categorization task for more than 30,000 trials, learning to categorize images of morphed cars into two groups with made-up names: SOVOR and ZUPUD.

To see how practice rewired the brain, the researchers tracked both the where and the when of brain activity. fMRI (functional magnetic resonance imaging) revealed which regions were involved, while EEG (electroencephalogram) captured the split-second timing of their signals. They repeated these measurements alongside behavioral tests at different stages of the training.

They found that extensive practice taught the visual areas to handle these category decisions themselves, allowing the brain to offload the work from the prefrontal cortex. The MRI also showed that the visual areas unplugged from the prefrontal cortex and formed new, stronger connections directly to the motor areas.

The most significant result of this rewiring was a dramatic improvement in multitasking. Since the practiced task no longer needed the limited resources of the prefrontal cortex, people could perform it alongside another attention-demanding task without any interference.

In terms of behavior, the participants reached high accuracy quickly, while their reaction times continued to drop with practice. Becoming faster without making more mistakes, alongside physical changes in the brain, showed that the task had become automatic and no longer depended on the brain's usual bottleneck.

These findings could help design training programs for jobs that require fast visual judgment, like radiology, security screening or industrial inspection. The researchers point out that the speed and automation acquired through practice come with a trade-off.

Automatic skills are fast, but they are less flexible than when the prefrontal cortex was in charge of the decision, so they may struggle if the rules suddenly change. Future research needs to clarify whether, and how, the brain can overcome this rigidity.

Patrick H. Cox et al, Extensive Experience Remodels Neural Task Circuitry to Escape the Frontal Bottleneck and Increase Automaticity of Categorization, Journal of Cognitive Neuroscience (2026). DOI: 10.1162/jocn.a.2618

Part 2

Comment by Dr. Krishna Kumari Challa on Thursday

A skill becomes automatic as the brain rewires itself to bypass its own bottleneck, new study suggests
Riding a bike, reading a book or folding laundry while watching TV can feel effortless, almost like your brain does it on autopilot. This ease comes from repetition, built through practicing the same task again and again. The prefrontal cortex (PFC), responsible for flexible thinking and decision-making, plays a role in this process, but it also creates a bottleneck. Although highly flexible, it can generally handle only one decision at a time, making multitasking difficult.
In a recent study, researchers wanted to understand how the brain changes when a person practices a specific task until it reaches cognitive automaticity. In this state, familiar actions can be performed quickly and efficiently with little conscious effort.

After sorting morphed car images more than 30,000 times, participants didn't just get better at the task. Their brains rewired themselves, shifting the work from slow, deliberate thinking to fast, effortless autopilot.

The brain's vision center, the vOTC (ventral occipito-temporal cortex), originally just recognized shapes, but with enough practice, it learned to make the categorization decisions itself. As the vision center could now handle the decision alone, it no longer needed constant guidance from the PFC. The two regions disengaged, and perception took over the job that thinking used to do.
Practice shifts the brain to autopilot
We categorize objects constantly, from recognizing a friend's face to sorting colours. Yet, most brain research on this skill only captures a few hours of practice in a lab, whereas real-world expertise takes months or years to hone the skills we rely on daily.
Earlier studies have shown that, under normal circumstances, the brain follows a two-stage process for categorization. First, the brain's visual areas identify an object's shape. Then the prefrontal cortex steps in to decide which category that shape belongs to.

The prefrontal cortex relies on cognitive control to keep the brain focused on the right task, but it can generally only handle one decision at a time. This creates a frontal bottleneck, so when you try to multitask, the two tasks interfere with each other.
However, once a task becomes automatic through practice, it no longer needs the prefrontal cortex watching over it, so it avoids the traffic jam.

The researchers hypothesized that extensive practice builds a perception-action loop, letting the brain skip the frontal bottleneck altogether. The prefrontal cortex teaches the visual system to recognize categories, then steps aside as the brain links what the eyes see directly to the motor regions of the brain.
Part 1

Comment by Dr. Krishna Kumari Challa on Wednesday

Their role in the farm effect was previously unknown. For the first time, therefore, the complete biological chain is visible: cow → barn air → bacteria → metabolic products → human receptors → protection against asthma.
The new findings can now be used by laboratory researchers to decipher the molecular and cellular mechanisms of the farm effect. This opens up the prospect of developing a drug that mimics the farm effect—without the need for children to spend time in barns.

Giulia Pagani et al, Gram-Positive Bacteria and the Inverse Association between Farm Exposure and Childhood Asthma, NEJM Evidence (2026). DOI: 10.1056/evidoa2500271

Part 2

Comment by Dr. Krishna Kumari Challa on Wednesday

Study identifies which bacteria trigger the 'farm effect' that makes children less prone to allergies

Children who grow up in a farm environment are less prone to allergies, asthma and hay fever than their classmates. This so-called farm effect has been identified in several observational studies worldwide. It is most likely attributable to the fact that various bacteria present in barn air prevent excessive inflammatory responses of the immune system that are characteristic of such diseases.

But exactly which bacteria? Now, an international team has answered this question. The researchers have shown for the first time which specific bacteria in barn air trigger the farm effect, which substances within those bacteria mediate the protection and which receptors in the body they bind to. Their findings have been published in NEJM Evidence.
Barn exposure–associated protection from asthma, hay fever, and atopic eczema is largely mediated by specific Gram-positive cow-derived bacteria, including Romboutsia timonensis and Glutamicibacter arilaitensis. Their metabolites (e.g., kynurenine, xanthine, α-linolenic and stearidonic acids) activate AhR and PPARγ in airway cells, attenuating excessive inflammatory responses and explaining most of the “farm effect.”
For years, we have been hearing about the hygiene hypothesis, which was first proposed in 1989. This came after three decades of dramatic increases in allergies, asthma and hay fever among children in Western industrialized countries. These are all conditions in which the immune system mounts an exaggerated inflammatory response and mistakenly attacks the body's own tissues.

According to the hygiene hypothesis, this happens because of understimulation in early childhood. The immune systems of children who encounter too few environmental microbes and common cold viruses are more likely to malfunction.

Girls and boys who grow up on farms and are exposed to a wider variety of microbes have the problem far less often.
As their immune systems constantly contend with bacterial 'sparring partners' from barn air, they are trained to avoid excessive inflammatory responses.

However, the hygiene hypothesis has not been definitively proven, as it is largely based on observational studies. This kind of research can only show more or less convincing correlation.
But with this new study, we can make a much stronger case, because we can identify the individual links in the proposed causal chain: the bacteria, the relevant microbial metabolic products and the human receptors.
The results
Researchers identified a small number of bacteria, which they can now pinpoint down to the species level - such as Romboutsia timonensis and Glutamicibacter arilaitensis. These Gram-positive bacteria together mediate two-thirds of the entire farm effect for asthma protection and half of the effect for hay fever and atopic eczema.
The bacteria originate in cows' digestive tracts, where they produce or metabolize substances like kynurenine, xanthine, alpha-linolenic acid and stearidonic acid. These compounds are easily inhaled and recognized by two receptors on human airway cells—AhR and PPARγ. These receptors have multiple functions, including in the immune system, where they appear to prevent excessive inflammatory responses.

Part 1

Comment by Dr. Krishna Kumari Challa on Wednesday

Dreams drain energy: The REM sleep paradox

The brain demands a lot of energy compared with other organs. However, it can also make do when energy supplies are scarce, flexibly processing information using what is available. How the brain resourcefully allocates this limited energy across internal states remains a key question in neuroscience.
Sleep provides a useful window into answering this question. Although sleep is associated with rest, the brain remains highly active. This is especially true during rapid eye movement (REM) sleep, the stage closely linked to dreaming and memory processing. REM sleep is sometimes called "paradoxical sleep" because the body is largely still while the brain shows wake-like activity. Researchers have now uncovered another paradox within REM sleep: While energy supply to the dreaming brain appears to rise, the energy molecule used directly by neurons falls.
REM sleep is preceded by a cortex-wide increase in brain blood volume and astrocytic pyruvate, indicating elevated energy supply and glycolytic activity, while neuronal ATP levels paradoxically decrease. During NREM sleep, theta-band neuronal activity predicts delayed vascular changes. The results suggest state-dependent rerouting of metabolic resources and high ATP consumption for internal processing during REM sleep.
Sleep may appear peaceful, but the brain is highly active—especially when dreaming.
Non-REM (NREM) sleep is best known for strong neuronal activity in the delta-band frequency, but subtle theta-band fluctuations are also present. The researchers found that these theta-band fluctuations could predict brain blood volume changes several seconds later, suggesting that the sleeping brain adjusts vascular dynamics to ongoing neuronal activity and metabolic demand.
The transition from NREM sleep into REM sleep showed a different pattern. About 50 seconds before the classically defined onset of REM sleep, brain blood volume began to rise. This increase started in the posterior cortex and spread forward, suggesting a large-scale metabolic preparation process. After REM sleep began, astrocytic pyruvate also increased, consistent with enhanced substrate availability or elevated astrocytic glycolytic activity. Paradoxically, however, neuronal ATP decreased.
Several mechanisms may explain the ATP decrease. Neurons may consume large amounts of ATP during REM sleep to support memory-related synaptic reorganization, hippocampal-cortical communication or large-scale circuit transitions. Alternatively, metabolic transfer from astrocytes to neurons may be altered, or mitochondrial ATP production may shift.

The research also points toward a broader principle of biological computation. Unlike conventional computers, animal brains operate under strict metabolic constraints. Rather than distributing energy uniformly, the brain may reroute energy depending on behavioural state, memory demand and internal needs.
Sleep is a vital function that can help consolidate memories and keep us mentally sharp the next day. These findings about energy and sleep are a crucial step forward in helping us understand the science behind sleep and how a good night's rest is important not just for our bodies—but for our minds too.

Yusuke Takahashi et al, Energy paradox in REM sleep: balancing supply and consumption in brain metabolism, Communications Biology (2026). DOI: 10.1038/s42003-026-10646-6

Comment by Dr. Krishna Kumari Challa on Wednesday

'Fire clouds', the ominous phenomenon seen in France

Firefighters battling devastating fires in France have had to contend with a new threat: immense fire clouds that create their own wind and even lightning that can spark fresh blazes.
Known as "fire clouds" or pyrocumulonimbus clouds, these ominous-looking thunderstorms are created by extreme wildfires and can exacerbate already dangerous conditions.

This phenomenon, which is new to France, is yet another consequence of human-caused climate change, according to French researcher Jean-Baptiste Filippi, who studies wildfires.

As firefighters in southwest France struggle to bring a forest inferno under control before yet another heat wave descends on the country.
What is a fire cloud?
It is a storm where a column of air forms above a fire.

It starts off as a cute little white cloud—a cumulus cloud, which forms because water vapor has turned into tiny droplets.

As the sun heats the ground, the water vapor suddenly condenses. The cumulus becomes a much larger cloud, containing thousands of tonnes of suspended water.
Then, when the surrounding air becomes heated enough, it forms a column with an anvil-shaped cloud—the cumulonimbus.

This condenses even more air and generates more energy, with updrafts of more than 150 kilometers (90 miles) an hour.

It then rains, but the rain evaporates before it reaches the ground.

But it still cools the atmosphere where it falls, creating strong downdrafts.
It is a common phenomenon in Portugal, California and Australia, where firefighters are more used to them. In Portugal, they had been rare until the deadly 2017 fires in Pedrogao Grande changed things.

Is climate change to blame?
Yes, it is. A consequence of global warming is more frequent heat waves. While thunderstorms are common in the region of this fire, thunderstorm conditions after three successive heat waves are a new combination.

Are they predictable?
Weather services can predict thunderstorms. But because these storms are located directly above a fire, we would need to know the fire's exact location in advance. That's impossible.

We can predict the conditions that will lead to these fires, but we won't know exactly where they are.
The biggest challenge is how unpredictable they are. The fire in France's southwestern Gironde region started with northerly winds, then westerly, then southerly, then easterly, then back again to the south, then the west...

On top of that, there is this potential energy in the atmosphere that meant that, locally, the convection column sucked up the embers and carried the fire further afield.

The local conditions became catastrophic, and the rate of the fire's spread was staggering.

Source: News Agencies

and original article.

Comment by Dr. Krishna Kumari Challa on Wednesday

Chemicals present in drinking water may carry a hidden risk tied to uterine cancer

In a recent study, researchers examined whether certain chemicals present in public drinking water are linked to uterine cancer, the most common gynecological cancer that has been steadily increasing in incidence.

Researchers found that long-term exposure to certain drinking water disinfectant by products was linked to a higher risk of uterine cancer. The risk was greatest among women living in areas with higher levels of trihalomethanes (THMs), chemicals formed when chlorine reacts with organic matter in water. This increased risk remained even when THM levels were within the government's legal limits.

Drinking water is a likely contributor, since it can carry contaminants that are known or suspected to cause cancer. While there are legal limits for contaminants, these limits are set based on what's technically possible, affordable and beneficial for health.

Common contaminants include natural substances like nitrate, arsenic and uranium, as well as byproducts created during water disinfection, such as THMs and haloacetic acids (HAA).

 The analysis found that exposure to certain chemicals used to disinfect public drinking water was associated with a higher risk of uterine cancer. In contrast, no association was found with other common contaminants, including nitrate, arsenic or uranium.

THMs, particularly chloroform, showed the strongest association with endometrioid tumors, which account for more than 95% of uterine cancer cases. Women exposed to the highest levels of THMs had an 18% higher risk of uterine cancer overall. Higher exposure to HAAs was associated with nearly twice the risk of developing nonendometrioid tumors.

The findings could help water utilities explore ways to reduce harmful disinfection byproducts while continuing to protect communities from waterborne infections. The results show an association between these chemicals in drinking water and uterine cancer risk, but they do not establish that they cause cancer.

Maya Spaur et al, Drinking Water Contaminant Exposures and Risk of Uterine Cancer, JAMA Network Open (2026). DOI: 10.1001/jamanetworkopen.2026.24391

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