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Comment by Dr. Krishna Kumari Challa on May 29, 2025 at 12:10pm

Science behind the surge in northern lights

If you feel like you've seen more of the northern lights painting the night sky lately, you'd be right. 

We're currently in a period of solar maximum, which is good news for aurora borealis enthusiasts. If you want to watch beautiful shows of the dancing northern lights, solar max is an ideal time to do that, say the experts.

The sun operates on a roughly 11-year cycle of magnetic activity. 

As the sun's magnetic field flips its north and south poles over this time, it switches between periods of lower magnetic activity (solar minimum) and periods of higher magnetic activity (solar maximum).

Surrounding the north and south magnetic poles of Earth are regions referred to as the "auroral ovals"—areas where aurora displays typically happen. During periods of solar max, these zones tend to expand a bit closer towards the equator, moving into areas where more people live.

There's more energy available, so they're more powerful, but they also move so they're at locations where they're more visible. 

Before any colors appear in the night skies over Earth, things need to turn explosive—literally—on the sun. The sun's surface is permeated by bundles of strong magnetic fields which poke out into the solar atmosphere. The ends of such magnetic loops represent cooler regions of the solar surface called sunspots. 

Loops can be stable for days and then suddenly they'll explode and launch a whole mass of charged particles into space—that's called a coronal mass ejection. It's basically a rapid release of the energy in these magnetic loops, but in the form of charged particles, which get a lot of kinetic energy and exceed the escape velocity of the sun's gravity field, blasting outwards into the solar system. 

Part 1

Comment by Dr. Krishna Kumari Challa on May 29, 2025 at 11:50am

Filtered car emissions still turn toxic after sunlight exposure, study reveals

A new international study reveals that emissions from modern gasoline cars—despite meeting the currently strictest European emission standards EURO 6d—can become significantly more harmful after being released into the atmosphere. The findings, published in Science Advances, challenge the assumption that filtered exhaust from EURO 6d-compliant vehicles is inherently safe.

The research focused on a gasoline vehicle equipped with a gasoline particulate filter (GPF), designed to drastically reduce primary particulate emissions. Freshly emitted exhaust showed no detectable cytotoxic effects on human lung cells. However, once the exhaust underwent "photochemical aging"—a natural transformation process driven by sunlight and atmospheric oxidants—it became substantially more toxic.

The aged emissions caused notable DNA damage and oxidative stress in both cancerous alveolar and normal bronchial epithelial cells. This toxicity was not only associated with newly formed particles, known as secondary organic and inorganic aerosols (SOA and SIA), but also with oxygenated volatile compounds, such as carbonyls, generated during their residence in the atmosphere.

 These findings point to a critical shortfall in current vehicle emissions testing and regulation.

While EURO 6d standards ensure low emissions at the tailpipe, they do not account for the chemical transformations those emissions undergo once released into the environment.

This new study shows that we are missing a big part of the picture by not considering how exhaust gases change—and become more harmful—after they leave the car.

The results have important implications for how air quality standards are set and monitored. Current regulations focus primarily on the emissions measured directly after combustion, without factoring in how these emissions interact with sunlight and atmospheric chemicals to form new, more harmful pollutants.

Mathilde N. Delaval et al, The efficiency of EURO 6d car particulate filters is compromised by atmospheric aging: In vitro toxicity of gasoline car exhaust, Science Advances (2025). DOI: 10.1126/sciadv.adq2348

Comment by Dr. Krishna Kumari Challa on May 29, 2025 at 11:34am

Humans are seasonal creatures, according to our circadian rhythms

It's natural to think that, with our fancy electric lights and indoor bedrooms, humanity has evolved beyond the natural influence of sunlight when it comes to our sleep routines.

But new research  shows that our circadian rhythms are still wild at heart, tracking the seasonal changes in daylight. Humans really are seasonal, even though we might not want to admit that in our modern context. 

Day length, the amount of sunlight we get,  really influences our physiology. The study shows that our biologically hardwired seasonal timing affects how we adjust to changes in our daily schedules.

This finding could enable new ways to probe and understand seasonal affective disorder, a type of depression that's connected to seasonal changes. It could also open new areas of inquiry in a range of other health issues that are connected to the alignment of our sleep schedules and circadian clocks.

Researchers have previously shown that our moods are strongly affected by how well our sleep schedules align with our circadian rhythms. 

This work may have deeper implications for mental health issues, like mood and anxiety, but also metabolic and cardiovascular conditions as well.

The research also showed there is a genetic component of this seasonality in humans, which could help explain the vast differences in how strongly individuals are affected by changes in day length.

For some people they might be able to adapt better, but for other people it could be a whole lot worse.

Exploring this genetic component will help researchers and doctors understand where individuals fall on that spectrum, but getting to that point will take more time and effort. For now, this study is an early but important step that reframes how we conceive of human circadian rhythms.

A lot of people tend to think of their circadian rhythms as a single clock. What  the researchers are showing is that there's not really one clock, but there are two. One is trying to track dawn and the other is trying to track dusk, and they're talking to each other.

The fact that circadian rhythms  in people exhibited a seasonal dependence is a compelling argument for just how hardwired this feature is in humans, which isn't altogether surprising, the researchers say.

Seasonal timing and interindividual differences in shiftwork adaptation, npj Digital Medicine (2025). DOI: 10.1038/s41746-025-01678-z

Comment by Dr. Krishna Kumari Challa on May 29, 2025 at 10:41am

The researchers studied a number of antibiotic classes and how body weight affects the drugs' metabolism. Drug classes analyzed in the study included β-lactams, aminoglycosides, glycopeptides, lipoglycopeptides, and quinolones, among others. Yet, not all antibiotics require special guidelines for the obese.
Obesity modestly alters the pharmacokinetics of β-lactam antibiotics, so evidence does not support routine dose adjustments [because of body weight].
For aminoglycosides and glycopeptides, the impact of obesity on pharmacokinetics is evident and weight-based dosing is recommended.
β-lactam antibiotics include such widely prescribed drugs as the penicillins, cephalosporins, carbapenems and monobactams. They are chemically characterized by a β-lactam ring in their chemical structure. The drugs are used against a wide range of bacterial infections, including Gram-positive and Gram-negative species. But there's no need to treat obese patients differently when it comes to β-lactam medications.

Doctors, meanwhile, frequently turn to aminoglycosides to treat extremely serious infections, especially those caused by Gram-negative bacteria. Aminoglycosides include such medications as gentamicin, streptomycin, and neomycin. These drugs work by disrupting critical protein production activity inside the bacterial cell. The drugs enter bacteria and bind to the 30S ribosomal subunit, resulting in flawed protein synthesis and death of the pathogens.

Guidelines were recommended for the use of this class in the obese as well as for glycopeptide antibiotics, which include the highly potent cell-wall-disrupting drug vancomycin.
Maintenance doses [of vancomycin] should be individualized and guided by therapeutic drug monitoring to increase the probability of achieving therapeutic yet non-toxic drug exposures, the researchers say.
The team did not provide a guideline based on total body weight for the quinolones, the drug class that includes the fluoroquinolones. However, the team's recommendations stressed special consideration for administering fluoroquinolones.
Higher or more frequent dosing resulting in higher systemic exposure should be considered for patients with obesity and severe deep-seated infections to reach adequate tissue concentration," the team asserted.

Data were sparse for other antibiotic classes and will require additional study, according to findings from the research.
When making decisions on dosing in obesity, the severity of illness, site of infection, susceptibility of the pathogen, and potential toxicity of the antibiotics should be considered, they concluded.

Anne-Grete Märtson et al, The pharmacokinetics of antibiotics in patients with obesity: a systematic review and consensus guidelines for dose adjustments, The Lancet Infectious Diseases (2025). DOI: 10.1016/S1473-3099(25)00155-0

Part 2

Comment by Dr. Krishna Kumari Challa on May 29, 2025 at 10:37am

Size matters when it comes to antibiotics. Obese patients may need customized doses of certain drugs

Obesity can have a distinct impact on the absorption, effectiveness and excretion of antibiotics, medications that have been in use for more than 80 years, but only now have consensus guidelines been proposed on prescribing the drugs for patients with substantial fat mass.

The new research arrives amid two major global health crises: In 2022, the World Health Organization declared that 43% of the global adult population is overweight, and an estimated 16% of adults are considered obese, some severely so. Also, in recent years, the WHO has stressed the need for more efficient use of antibiotics to preserve their usefulness as drug-resistant superbugs become an increasingly lethal threat.

Now, an international team of medical investigators reports that obesity can interfere with antibiotics, resulting in too much or too little drug exposure to treat infections. And because dosages that effectively work in normal weight individuals don't seem to treat the obese, the research team has developed obesity-specific antibiotic dosing guidelines for certain classes of the drugs.

Writing in The Lancet Infectious Diseases, the team describes its research as an in-depth systematic review of the medical literature on dosing and antibiotics. Conclusions drawn from the research created the framework for the guidelines.

Obesity can alter antibiotic pharmacokinetics due to physiological changes, such as body composition and organ dysfunction that result in increased or decreased drug exposures in plasma or at the site of infection, say the researchers.

Researchers used the standard definition of obesity, a BMI of 30 or higher, and underscored that "substantial changes can occur in the volume of [systemic antibiotic] distribution due to increased fat and muscle mass." In other words, obesity can alter how antibiotics are absorbed, distributed and excreted from the body.

The team began its systematic investigation with a review of 6,113 studies on obesity and antibiotic dosing. After eliminating duplicate studies, the team narrowed that number to 128 studies from which conclusions in the study were drawn.

A pictorial chart in the study illustrated problems facing the obese when it comes to taking antibiotics: increased fat mass, impaired kidney and/or liver function. Of special concern in the liver is the dysfunction of cytochrome P450, the group of enzymes responsible for metabolizing drugs.

Part 1

Comment by Dr. Krishna Kumari Challa on May 28, 2025 at 3:35pm

Trees May Be Able to Warn Us When a Volcano Is About to Erupt

The science of predicting volcanic eruptions can genuinely save lives – potentially, a lot of lives – and researchers have shown that tree leaf colors can act as warning signals around a volcano that's about to blow. As volcanoes get more active and closer to an eruption, they push magma up closer to the surface, releasing higher levels of carbon dioxide. That in turn can boost the health of the surrounding trees, making leaves greener. And those changes – specifically in the measurement known as the normalized difference vegetation index (NDVI) – can be spotted by satellites in space. We could be looking at an early warning system for eruptions that doesn't require any local field work or ground sensors, so it could work in remote and difficult-to-access areas.

https://www.sciencedirect.com/science/article/abs/pii/S003442572400...

Comment by Dr. Krishna Kumari Challa on May 28, 2025 at 2:42pm

Silent X chromosome awakens with age: New explanation for sex differences in age-related diseases

Women age differently from men when it comes to health—particularly in conditions like cardiovascular disease and neurodegenerative disorders such as dementia and Parkinson's.

A research team proposed a new explanation for this. In aging female mice, genes on the previously silenced second X chromosome become active again. This mechanism might also influence women's health later in life. The study is published in the journal Nature Aging.

Unlike men, who carry one X and one Y chromosome, women have two X chromosomes in each cell. However, one of the two X chromosomes is effectively silenced. It folds into a compact structure known as the Barr body and can no longer be read. Without this mechanism, the genes on the X chromosome would be read twice as often in women as in men.

Scientists have known for some time that some genes can escape inactivation in the Barr body, resulting in higher gene activity in women. These genes are suspected to influence disease.

Researchers have now shown for the first time that with increasing age, more and more genes escape the inactivation of the Barr body.

The researchers examined the major organs of mice at different stages of life. In the older animals, the proportion of genes that had escaped was on average twice as high as in adult animals—6% instead of 3% of the genes on the X chromosome. In some organs, the numbers were even higher: in the kidneys, for instance, nearly 9%.

With aging, epigenetic processes gradually loosen the tightly packed structure of the inactive X chromosome. This mainly happens at the ends of the chromosome, allowing for genes located in those regions to be read again.

Many of the genes that become active again with age are associated with disease. These new  findings are based on mice, but since the X chromosome is very similar in humans,  the same may happen in aging women. 

According to the researchers, this doubled gene activity could have positive effects in some cases and negative effects in others.

ACE2, for example—a gene that escapes in the lungs with age—can help limit pulmonary fibrosis. Increased activity of the gene TLR8 in old age, however, may play a role in autoimmune diseases such as late-onset lupus.

Sex differences in age-related disease are incredibly complex.

So far, scientific explanations have mostly focused on hormonal or lifestyle factors. While the role of the X chromosome and some escape genes have been studied before, the discovery that many genes on the inactive X can reactivate with age opens up entirely new lines of research.

Sarah Hoelzl et al, Aging promotes reactivation of the Barr body at distal chromosome regions, Nature Aging (2025). DOI: 10.1038/s43587-025-00856-8

Comment by Dr. Krishna Kumari Challa on May 28, 2025 at 2:24pm

Scientists have attempted to expand its scope to active imaging applications such as light detection and ranging or LiDAR, but the lack of suitable thermal light sources and robust image reconstruction algorithms make the process challenging.

To overcome these issues, the researchers created an intensity interferometer setup with pseudothermal illumination achieved by superimposing light from 8-phase-independent multiple laser emitters. This setup included two telescopes and an infrared laser system on a shared optical bench.

The laser system produced thermal illumination, and reconstructed sparse, noisy data being collected into a high-resolution image with the help of a computational algorithm.

To test the super-resolution capabilities of the device, the letters "USTC" were crafted out of hollowed-out blackened aluminum sheets which were then covered in retroreflective sheets and used as a complex imaging target positioned over a kilometer away.
Using the designed active intensity interferometer, the researchers successfully demonstrated super-resolution imaging of millimeter-scale targets at a distance of 1.36 km in an outdoor urban environment. The imaging system achieved a resolution of 3 mm, which is 14 times higher than the diffraction limit of a single telescope, typically around 42.5 mm.

Once scaled for use beyond the laboratory, this device could significantly accelerate advancements in long-range, high-resolution remote sensing, surveillance, and non-invasive imaging in challenging environments.

Lu-Chuan Liu et al, Active Optical Intensity Interferometry, Physical Review Letters (2025). DOI: 10.1103/PhysRevLett.134.180201

Part 2

Comment by Dr. Krishna Kumari Challa on May 28, 2025 at 2:22pm

New high-resolution laser device reads millimeter-scale text from a mile away

According to the study published in Physical Review Letters, the developed setup includes multiple laser emitters that enable super-resolution imaging of targets as small as millimeters in scale from a 1.36 kilometers (0.85 miles) distance in an outdoor urban environment. The device successfully images letter-shaped physical targets measuring 8×9 mm, with letter widths of 1.5 mm, placed at the far end of its imaging range.

Interferometry is a widely used imaging technique in astronomy which works by merging light from different sources to create an interference pattern. These interference patterns are formed when light waves interact to either reinforce or cancel each other depending on their phase differences. These patterns carry detailed information about the object or phenomenon being studied.
Intensity interferometry, on the other hand, does not rely on combining light amplitudes or maintaining phase information but on light from a single source being measured separately by two detectors or telescopes, and the variations in their recorded intensities are compared.

Studying intensity fluctuations, correlations and their changes with the distance between the detectors can help extract spatial details about the object being studied.

What makes intensity interferometry stand out? It can cut through atmospheric turbulence and ignore flaws in telescope optics—making it ideal for long-distance, high-resolution imaging. Yet, its applications have mostly been limited to observing bright stars or objects that can be lit up with nearby light sources.

Part 1

Comment by Dr. Krishna Kumari Challa on May 27, 2025 at 12:49pm

What would we see at the speed of light?

What does the speed of light look like on earth?

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