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Comment by Dr. Krishna Kumari Challa on July 29, 2025 at 11:27am

Changes in female body odor during ovulation elicit measurable reactions in men, finds study

Researchers explored how female body odor can influence behaviors in men. They found that certain scent compounds in female body odor increased during ovulation and can subtly influence how men feel.

When these scents were added to armpit odor samples, men rated them as more pleasant and faces associated with the samples as more attractive. The scents also seemed to reduce stress. The team states this is not evidence of pheromones in humans, but that smell might subtly shape how people interact.

This study show something measurable and interesting is happening, analogous to the idea of pheromones.

The researchers  identified three body odor components that increased during women's ovulatory periods. When men sniffed a mix of those compounds and a model armpit odor, they reported those samples as less unpleasant, and accompanying images of women as more attractive and more feminine.

Furthermore, those compounds were found to relax the male subjects, compared to a control, and even suppressed the increase in the amount of amylase (a stress biomarker) in their saliva. These results suggest that body odor may in some way contribute to communication between men and women.

Previous studies by different groups have already discovered that female body odor changes throughout the menstrual and that the changes in the ovulatory phase can be perceived by men and are reported as being pleasant. But the specific nature of these odors went unidentified and is something this latest study managed to achieve.

 These tests were done "blind," meaning the participants did not receive any hints about what they were smelling or why, with some participants being given nothing at all as a measure of control.

This way, psychological factors and expectations were reduced or eliminated.

But the researchers say they cannot conclusively say at this time that the compounds they found which increase during the ovulation period are human pheromones. 

Human ovulatory phase-increasing odors cause positive emotions and stress-suppressive effects in males, iScience (2025). DOI: 10.1016/j.isci.2025.113087

Comment by Dr. Krishna Kumari Challa on July 29, 2025 at 11:19am

Coolness hits the skin uniquely; now scientists know why

Researchers have illuminated a complete sensory pathway showing how the skin communicates the temperature of its surroundings to the brain.

This discovery, believed to be the first of its kind, reveals that cool temperatures have their own pathway, indicating that evolution has created different circuits for hot and cold temperatures. This creates an elegant solution for ensuring precise thermal perception and appropriate behavioral responses to environmental changes.

 More than 70% of people who have undergone chemotherapy experience pain caused by cool temperatures. 

The new study found that the neural circuit responsible for sensing innocuous cool does not mediate this type of cold pain. But, in understanding how the cool-sensing circuitry works when it's functioning properly under normal conditions, researchers now have a better chance of discovering what goes wrong in disease or injury. It could also aid in the development of targeted therapies to restore healthy sensation without impairing normal temperature perception.

The researchers used   sophisticated imaging techniques and electrophysiology to observe how mice transmitted the sensation of cool temperatures from their skin to the brain.

These tools have allowed them to identify the neural pathways for chemical itch and mechanical itch previously.

The cool signal starts at the skin, which is home to molecule sensors that can detect a specific range of temperatures between about 15 and 25 degrees Celsius—equivalent to 59 and 77 degrees Fahrenheit. When those sensors engage, they excite primary sensory neurons, which send the cool signal to the spinal cord. Here, the team found that the signal is amplified by specialized interneurons, which then activate projection neurons that connect to the brain.

With the amplifier disabled, the cool signal becomes lost in the noise, the team found.

Although the study was performed in mice, each component of the circuit has been shown to be in humans through genetic sequencing. 

So it's likely that we have the same pathway to thank for the refreshing sensation of stepping into an air-conditioned room on a hot summer day.

 A dedicated skin-to-brain circuit for cool sensation in mice, Nature Communications (2025). DOI: 10.1038/s41467-025-61562-y

Comment by Dr. Krishna Kumari Challa on July 29, 2025 at 11:11am

Increasing forest cover also carries significant benefits for carbon sequestration, as both the CLT itself and the forests needed to create it store carbon. Depending on how quickly the global market adopts CLT, researchers predict that CLT demand would increase the amount of carbon stored on land by 20.3–25.2 gigatons (carbon dioxide equivalent) by 2100. This effect is amplified by lowering demand for traditional construction materials like steel and concrete caused by an increase in CLT demand.
When we increase usage of CLT, we decrease demand for those traditional construction materials. When you use less traditional materials, you emit less greenhouse gases while creating those materials
All of these effects combine over the entire lifecycle of the CLT to create the environmental benefits.

Kai Lan et al, Global land and carbon consequences of mass timber products, Nature Communications (2025). DOI: 10.1038/s41467-025-60245-y

Part 2

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Comment by Dr. Krishna Kumari Challa on July 29, 2025 at 11:10am

Building a high rise out of wood? Cross-laminated timber could make it possible

A new study finds that adopting cross-laminated timber as a primary construction material could have significant environmental benefits, from carbon storage to global reforestation and increased forest cover.

Cross-laminated timber (CLT) is created by stacking multiple layers of timber and then adhering the layers together. This results in strong, light wooden panels up to 60 feet long, big enough to form an entire wall or other structures. These panels are also fire-resistant. When exposed to fire, the outer layer of a CLT panel turns to char, which seals the rest of the wood away and prevents it from igniting.

Because CLT is such a promising construction material, researchers wanted to determine the effects of adopting it more broadly. To do this, they combined an environmental assessment tool known as a life cycle assessment (LCA), which tracks the environmental effects of a product throughout its life cycle, with the Global Timber Model (GTM), an economic model which examines the effects of land use and policy on the global timber market.

Researchers integrated data from the two tools to predict the economic and environmental impacts of a broad move toward CLT in construction globally. They found that a move to CLT would increase forest cover worldwide, as the production of CLT would necessitate larger and more intensely managed forests to supply raw timber. While a small portion of natural forest would need to be converted, the increase in managed forests and plantation land could lead to an overall increase in forest area of nearly 30 million hectares globally by 2100.

Economically, the GTM showed that increased demand for CLT results in an increase in timber prices, as projected forest cover increases only add around 11% to the global wood supply even in the most aggressive adoption scenario. This leads to a 26.3% increase in sawtimber prices and a 25.9% increase in pulpwood prices by 2100, compared to no CLT adoption. Sawtimber is used to make traditional wood products like plywood, lumber and wood panels, while pulpwood is used in paper products. Part 1

Comment by Dr. Krishna Kumari Challa on July 29, 2025 at 11:09am

Building a high rise out of wood? Cross-laminated timber could make it possible

A new study finds that adopting cross-laminated timber as a primary construction material could have significant environmental benefits, from carbon storage to global reforestation and increased forest cover.

Cross-laminated timber (CLT) is created by stacking multiple layers of timber and then adhering the layers together. This results in strong, light wooden panels up to 60 feet long, big enough to form an entire wall or other structures. These panels are also fire-resistant. When exposed to fire, the outer layer of a CLT panel turns to char, which seals the rest of the wood away and prevents it from igniting.

Because CLT is such a promising construction material, researchers wanted to determine the effects of adopting it more broadly. To do this, they combined an environmental assessment tool known as a life cycle assessment (LCA), which tracks the environmental effects of a product throughout its life cycle, with the Global Timber Model (GTM), an economic model which examines the effects of land use and policy on the global timber market.

Researchers integrated data from the two tools to predict the economic and environmental impacts of a broad move toward CLT in construction globally. They found that a move to CLT would increase forest cover worldwide, as the production of CLT would necessitate larger and more intensely managed forests to supply raw timber. While a small portion of natural forest would need to be converted, the increase in managed forests and plantation land could lead to an overall increase in forest area of nearly 30 million hectares globally by 2100.

Economically, the GTM showed that increased demand for CLT results in an increase in timber prices, as projected forest cover increases only add around 11% to the global wood supply even in the most aggressive adoption scenario. This leads to a 26.3% increase in sawtimber prices and a 25.9% increase in pulpwood prices by 2100, compared to no CLT adoption. Sawtimber is used to make traditional wood products like plywood, lumber and wood panels, while pulpwood is used in paper products. Part 1

Comment by Dr. Krishna Kumari Challa on July 27, 2025 at 11:53am

Forever chemicals, lasting effects: Prenatal PFAS exposure shapes baby immunity

New research reveals that tiny amounts of PFAS—widely known as "forever chemicals"—cross the placenta and breast milk to alter infants' developing immune systems, potentially leaving lasting imprints on their ability to fight disease.

 Researchers tracked 200  healthy mother–baby pairs, measuring common PFAS compounds in maternal blood during pregnancy and then profiling infants' key T‑cell populations at birth, six months, and one year. By age 12 months, babies whose mothers had higher prenatal PFAS exposure exhibited significantly fewer T follicular helper (Tfh) cells—vital coaches that help B cells produce strong, long‑lasting antibodies—and disproportionately more Th2, Th1, and regulatory T cells (Tregs), each linked to allergies, autoimmunity, or immune suppression when out of balance.

The study is published in the journal Environmental Health Perspectives.

Identification of these particular cells and pathways opens up the potential for early monitoring or mitigation strategies for the effects of PFAS exposure, in order to prevent lifelong diseases, stress the researchers.

Darline Castro Meléndez et al, In utero per – and polyfluoroalkyl substances (PFAS) exposure and changes in infant T helper cell development among UPSIDE-ECHO cohort participants., Environmental Health Perspectives (2025). DOI: 10.1289/EHP16726

Comment by Dr. Krishna Kumari Challa on July 27, 2025 at 11:48am

Beetroot juice lowers blood pressure in older people by changing oral microbiome, study shows

The blood pressure-lowering effect of nitrate-rich beetroot juice in older people may be due to specific changes in their oral microbiome, according to the largest study of its kind.

Researchers  conducted the study, published in the journal Free Radical Biology and Medicine, comparing responses between a group of older adults to that of younger adults. Previous research has shown that a high nitrate diet can reduce blood pressure, which can help reduce the risk of heart disease. The paper is titled "Ageing modifies the oral microbiome, nitric oxide bioavailability and vascular responses to dietary nitrate supplementation."

Nitrate is crucial to the body and is consumed as a natural part of a vegetable-rich diet. When the older adults drank a concentrated beetroot juice shot twice a day for two weeks, their blood pressure decreased—an effect not seen in the younger group.

The new study provides evidence that this outcome was likely caused by the suppression of potentially harmful bacteria in the mouth.

An imbalance between beneficial and harmful oral bacteria can decrease the conversion of nitrate (abundant in vegetable-rich diets) to nitric oxide. Nitric oxide is key to healthy functioning of the blood vessels, and therefore the regulation of blood pressure.

Encouraging older adults to consume more nitrate-rich vegetables could have significant long-term health benefits. The good news is that if you don't like beetroot, there are many nitrate-rich alternatives, like spinach, arugula, fennel, celery and kale, say the researchers.

Anni Vanhatalo et al, Ageing modifies the oral microbiome, nitric oxide bioavailability and vascular responses to dietary nitrate supplementation, Free Radical Biology and Medicine (2025). DOI: 10.1016/j.freeradbiomed.2025.07.002

Comment by Dr. Krishna Kumari Challa on July 27, 2025 at 11:39am

New study shows how sweat really forms

If you're currently experiencing a hot summer, the chances are the sweat is pouring off you, soaking your clothing. This clear, odorless substance is a vital component of a healthy bodily function that helps cool you down and prevent overheating. However, the process by which sweat forms and emerges from the skin is more intricate than previously thought.

Sweat may often appear as a series of discrete droplets seeping from the skin, but a new study in the Journal of the Royal Society Interface tells a different story. Instead of forming distinct beads, sweat rises like a tide through the pores to saturate the top layer of skin. It gathers in a shallow pool in each pore before merging with others to form a complete film across the skin's surface.

These  findings challenge the traditional conceptualization of sweat emerging from pores as hemispherical droplets, demonstrating that sweat commonly forms a shallow meniscus in the pore.

In the experiments conducted, the subjects were heated, cooled, then heated again while researchers measured the sweat forming on their foreheads. They began to perspire within 15 minutes, with sweat emerging and evaporating from their pores in a repeating cycle. Instead of forming little droplets, the sweat was nearly flat, settling in each pore until it spilled out and connected with sweat from other pores to create a puddle, which then formed a film coating the skin.

The sweat soaked through the outermost layer of dead skin cells (stratum corneum), and once it was completely soaked, the sweat pooled on top. When the participants were cooled down, the newly formed film of sweat rapidly evaporated, leaving behind a thin layer of salt.

After heating the participants again, the sweat emerged quicker than before. This time, the salt layer allowed the sweat to soak more quickly into the stratum corneum, and the second sweat layer bypassed the droplet stage entirely, emerging as a film.

 Cibin T. Jose et al, A micro-to-macroscale and multi-method investigation of human sweating dynamics, Journal of The Royal Society Interface (2025). DOI: 10.1098/rsif.2025.0407

Comment by Dr. Krishna Kumari Challa on July 27, 2025 at 10:59am

Electrical stimulation of facial muscles influences how people perceive others' emotions, study finds

Psychology research suggests that the human body, particularly the muscles on our face, plays a key part in the processing of others' emotions. For instance, past findings suggest that when we see another person smiling or frowning, we often unconsciously mimic their facial expression, and this helps us interpret their emotions.

Theories suggest that the mimicry of facial expressions sends signals from our facial muscles to the brain, broadly referred to as "facial feedback," which in turn contributes to the interpretation of other people's emotions. So far, however, the contribution of this feedback to emotion recognition and how its contribution unfolds over time remain poorly understood.

Researchers recently carried out a study to investigate the effects of facial feedback on the perception of emotions at different stages of visual processing, using a technique known as facial neuromuscular electrical stimulation (fNMES). Their findings, published in Communications Psychology, suggest that signals generated by the movements of muscles on people's faces influence how they interpret the emotions of others, particularly during the earlier stages of visual processing.

When the researchers stimulated Zygomaticus Major muscles (the main muscles involved in smiling), people reported to feel happier, however when they stimulated the Depressor Anguli Oris muscles (involved in frowning), people reported the opposite. In another paper, they found that stimulating smiling muscles made people more likely to see happiness in ambiguous faces.

A key implication of this  study is that facial feedback can reduce the brain's reliance on visual processing when interpreting emotional expressions.

This suggests that when the body provides relevant emotional signals—such as those from the smiling muscles—the visual system doesn't need to work as hard to make sense of visual ambiguities. These results have important consequences for how we understand emotion perception: it's not just about what we see, but also about what our body is telling us.

J. Baker et al, Electrical stimulation of smiling muscles reduces visual processing load and enhances happiness perception in neutral faces, Communications Psychology (2025). DOI: 10.1038/s44271-025-00281-y.

Comment by Dr. Krishna Kumari Challa on July 26, 2025 at 11:06am

Globally, over 2.5 million COVID deaths prevented worldwide thanks to vaccines, data indicate

Thanks to vaccinations against SARS-CoV-2 in the period 2020–2024, 2.533 million deaths were prevented at the global level; one death was avoided for every 5,400 doses of vaccine administered.

Some 82% of the lives saved by vaccines involved people vaccinated before encountering the virus, 57% during the omicron period, and 90% involved people aged 60 years and older. In all, vaccines have saved 14.8 million years of life (one year of life saved for 900 doses of vaccine administered).

These are some of the data released in an unprecedented study published in the journal Jama Health Forum.

The experts studied worldwide population data, applying a series of statistical methods to figure out who among the people who became ill with COVID did either before or after getting vaccinated, before or after the omicron period, and how many of them died (and at what age).

They compared this data with the estimated data modeled in the absence of COVID vaccination and were then able to calculate the numbers of people who were saved by COVID vaccines and the years of life gained as a result of them.

It also turned out that most of the saved years of life (76%) involved people over 60 years of age, but residents in long-term care facilities contributed only 2% of the total number. Children and adolescents (0.01% of lives saved and 0.1% of life years saved) and young adults aged 20–29 (0.07% of lives saved and 0.3% of life years saved) contributed very little to the total benefit.

Most of the benefits, in terms of lives and life-years saved, have been secured for a portion of the global population who are typically more fragile, the elderly.

Global Estimates of Lives and Life-Years Saved by COVID-19 Vaccination During 2020-2024, JAMA Health Forum (2025).

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