Comment

Comment by Dr. Krishna Kumari Challa on Tuesday

Half of the universe's hydrogen gas, long unaccounted for, has been found

Astronomers tallying up all the normal matter—stars, galaxies and gas—in the universe today have come up embarrassingly short of the total matter produced in the Big Bang 13.6 billion years ago. In fact, more than half of normal matter—half of the 15% of the universe's matter that is not dark matter—cannot be accounted for in the glowing stars and gas we see.

New measurements, however, seem to have found this missing matter in the form of very diffuse and invisible ionized hydrogen gas, which forms a halo around galaxies and is more puffed out and extensive than astronomers thought.

The findings not only relieve a conflict between astronomical observations and the best, proven model of the evolution of the universe since the Big Bang, they also suggest that the massive black holes at the centers of galaxies are more active than previously thought, fountaining gas much farther from the galactic center than expected—about five times farther, the team found.

The new  measurements are certainly consistent with finding all of the gas. 

The results of the study, co-authored by 75 scientists from institutions around the world, have been presented at recent scientific meetings, posted as a preprint on arXiv and are undergoing peer review at the journal Physical Review Letters.

While the still mysterious dark matter makes up the bulk—about 84%—of matter in the universe, the remainder is normal matter. Only about 7% of normal matter is in the form of stars, while the rest is in the form of invisible hydrogen gas—most of it ionized—in galaxies and the filaments that connect galaxies in a kind of cosmic network.

The ionized gas and associated electrons strung out in this filament network are referred to as the warm-hot intergalactic medium, which is too cold and too diffuse to be seen with the usual techniques at astronomers' disposal, and therefore has remained elusive until now.

In the new paper, the researchers estimated the distribution of ionized hydrogen around galaxies by stacking images of approximately 7 million galaxies—all within about 8 billion light-years of Earth—and measuring the slight dimming or brightening of the cosmic microwave background caused by a scattering of the radiation by electrons in the ionized gas, the so-called kinematic Sunyaev-Zel'dovich effect.

B. Hadzhiyska et al, Evidence for large baryonic feedback at low and intermediate redshifts from kinematic Sunyaev-Zel'dovich observations with ACT and DESI photometric galaxies, arXiv (2024). DOI: 10.48550/arxiv.2407.07152

Comment by Dr. Krishna Kumari Challa on Tuesday

Scientists uncover why carbon-rich meteorites rarely reach Earth

An international team of researchers may have answered one of space science's long-running questions—and it could change our understanding of how life began. Carbon-rich asteroids are abundant in space yet make up less than 5% of meteorites found on Earth.

Published in Nature Astronomy, researchers analyzed close to 8,500 meteoroids and meteorite impacts, using data from 19 fireball observation networks across 39 countries—making it the most comprehensive study of its kind. The paper is titled "Perihelion history and atmospheric survival as primary drivers of Earth's meteorite record."

The team discovered Earth's atmosphere and the sun act like giant filters, destroying fragile, carbon-rich (carbonaceous) meteoroids before they reach the ground.

Scientists have long suspected that weak, carbonaceous material doesn't survive atmospheric entry. What this research shows is many of these meteoroids don't even make it that far: they break apart from being heated repeatedly as they pass close to the sun. The ones that do survive getting cooked in space are more likely to also make it through Earth's atmosphere.

The study also found meteoroids created by tidal disruptions—when asteroids break apart from close encounters with planets—are especially fragile and almost never survive atmospheric entry.

Carbonaceous meteorites are particularly important because they contain water and organic molecules—key ingredients linked to the origin of life on Earth. Carbon-rich meteorites are some of the most chemically primitive materials we can study—they contain water, organic molecules and even amino acids.

However, scientists have so few of them in their meteorite collections that they risk having an incomplete picture of what's actually out there in space and how the building blocks of life arrived on Earth.

Understanding what gets filtered out and why is key to reconstructing our solar system's history and the conditions that made life possible.

 Patrick M. Shober et al, Perihelion history and atmospheric survival as primary drivers of the Earth's meteorite record, Nature Astronomy (2025). DOI: 10.1038/s41550-025-02526-6

Comment by Dr. Krishna Kumari Challa on Tuesday

Besides harming health, high levels of surface ozone reduce photosynthesis by damaging photosystems, CO₂ fixation and pigments. This leads to a reduction in carbon assimilation that results in the decline of crop yields.

According to the ozone study, India's rice yield loss due to ozone pollution rose from 7.39 million tons to 11.46 million tons between 2005 and 2020, costing around US$2.92 billion and impacting food security.

Even if precursor emissions remain at the current level, climate change alone could contribute to the increase in surface ozone in the highly polluted regions of South Asia by 2050 with the Indo-Gangetic Plains, one of the most fertile regions in the region, likely to face significant crop yield losses.

Much of the surface ozone generated is taken care of by nature, such as the monsoon rains. Dealing with the reported increase in ozone levels is best done by reducing the precursors—nitrogen oxides, methane and PM_2.5.

G.S. Gopikrishnan et al, Exposure to surface ozone and its associated health effects and economic burden in India, Global Transitions (2025). DOI: 10.1016/j.glt.2025.03.002

Footnotes:

1. Estimating the effect of annual PM2-5 exposure on mortality in India: a difference-in-differences approach, The Lancet Planetary Health (2024). DOI: 10.1016/S2542-5196(24)00248-1. www.thelancet.com/journals/lan … (24)00248-1/fulltext

Part 2

Comment by Dr. Krishna Kumari Challa on Tuesday

'Ozone-climate penalty' adds to India's air pollution

India's cities are already ranked among the world's most polluted, based on concentrations of fine particulate matter in the air. Now new research indicates they are battling rising levels of another life-threatening pollutant—surface ozone.

A study published in the journal Global Transitions says deaths from ozone in India exceeded 50,000 in 2022 and caused losses of around US$16.8 billion—about 1.5 times the government's total health spending that year.

Surface ozone is a toxic gas that not only affects public health but also impacts ecosystems and climate due to the greenhouse effect.

Ozone, a variant of oxygen, occurs at ground level as well as in the upper atmosphere. Formed naturally, the ozone in the stratosphere helps filter out harmful ultraviolet rays that are a part of the sun's radiation. However, surface ozone, also called ground-level ozone, is generated by interactions between pollutants. For example, nitrogen oxides found in vehicular exhaust can react with volatile organic compounds released by industrial activity and waste dumps to produce ozone. Surface ozone is the primary component of smog and can have negative effects on human health and the environment.

Short-term exposure to ozone increases the risk of death from heart disease, stroke, hypertension and respiratory issues, while long-term exposure may decrease lung capacity, induce oxidative stress, suppress immune response and cause lung inflammation.

Climate change, rising temperatures and altered weather patterns can raise surface ozone in a phenomenon described by experts as the "ozone-climate penalty". Factors that affect ozone generation include solar radiation, humidity, precipitation and the presence of precursors—substances that lead to the formation of a pollutant through a chemical reaction—such as methane, nitrogen oxides and volatile organic compounds.

Ozone pollution increases during the hot summer months and declines during the monsoon period from June to September as heavy rains wash out the pollutants, and reduced solar radiation limits photochemical reactions.

Critically, human exposure to fine particulate matter—known as PM_2.5—may worsen the health effects of ozone. 

PM_2.5 refers to particles smaller than 2.5 microns, which can enter the bloodstream through the lungs.

According to the 2024 World Air Quality Report, 11 of the world's 20 cities carrying the highest burden of PM_2.5 are in India.

A study (1) published in The Lancet Planetary Health found that the whole of the population of India lives in areas where PM_2.5 levels exceed WHO guidelines.

Part 1

Comment by Dr. Krishna Kumari Challa on Sunday

Venom characteristics of a deadly snake depends on climate .... and can be predicted from local climate

Local climate can be used to predict the venom characteristics of a deadly snake that is widespread in India, helping clinicians to provide targeted therapies for snake bite victims, according to a study published in PLOS Neglected Tropical Diseases

Russell's viper (Daboia russelii) is found across the Indian subcontinent and is responsible for over 40% of snake bite-related deaths in India each year. Its venom is extremely variable, and snake bites cause different symptoms in different regions of India.

The toxic effects of snake venom are caused by the concentrations of different enzymes, which can be influenced by many factors, including prey availability and climate. However, the factors driving variation in Russell's viper venom are unknown.

To investigate, researchers analyzed venom samples from 115 snakes collected in 34 locations across India. They tested the activity of venom toxins, including enzymes that break down proteins, phospholipids and amino acids.

Next, they used historical climate data to understand the relationship between venom composition and the local climate where the snakes were caught. They found that temperature and rainfall partly explained regional variation in snake venom composition.

Protease activity showed the closest relationship to climate variables, whereas the activity of amino acid oxidases was unaffected by climate. Snakes in drier regions of India tended to have higher protease activity.

The researchers used this data to create a map of expected venom types across Russell's viper's range in India, which could be used to predict the clinical symptoms of snake bites in different regions.

The venom maps developed in this study could help clinicians select the most appropriate treatment for patients with snake bites, or to develop targeted therapies such as toxin-specific antibodies, the researchers say.

PLOS Neglected Tropical Diseases (2025). DOI: 10.1371/journal.pntd.0012949

Comment by Dr. Krishna Kumari Challa on April 12, 2025 at 3:41pm

Researchers identify simple rules for folding the genome

An international team of researchers have identified rules that tell cells how to fold DNA into the tightly packed, iconic X-shaped chromosomes formed during mitosis that help ensure the accurate passing of genetic information between cells during cell division.

Published in the journal Science, these findings illuminate basic biological functions underlying mitosis on a micrometer scale. Understanding how the cells accomplish this critical task may provide important new insights into inheritance and DNA stability and repair, as well as genetic mutations that lead to human diseases such as cancer.

 Kumiko Samejima et al, Rules of engagement for condensins and cohesins guide mitotic chromosome formation, Science (2025). DOI: 10.1126/science.adq1709

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Comment by Dr. Krishna Kumari Challa on April 10, 2025 at 11:38am

While often discussed as two main types, diabetes actually encompasses several categories, including type 1, type 2, gestational diabetes, and other specific types like MODY (Maturity-Onset Diabetes of the Young).
Here's a breakdown of the main types of diabetes:
Type 1 Diabetes:
An autoimmune condition where the body's immune system mistakenly attacks and destroys the insulin-producing cells in the pancreas.
Type 2 Diabetes:
A condition where the body becomes resistant to insulin, and the pancreas may not produce enough insulin to maintain normal blood sugar levels.
Gestational Diabetes:
A form of diabetes that develops during pregnancy, often due to hormonal changes that make the body less sensitive to insulin.
Other Specific Types of Diabetes:
MODY (Maturity-Onset Diabetes of the Young): A genetic form of diabetes that typically develops in childhood or early adulthood, often before the age of 25.
LADA (Latent Autoimmune Diabetes in Adults): A type of diabetes that is similar to type 1 but develops more slowly, with the damage to the insulin-producing cells in the pancreas happening gradually.
Neonatal Diabetes: A rare form of diabetes that occurs in newborns or infants.
Secondary Diabetes: Diabetes that develops as a result of other medical conditions or medications, such as cystic fibrosis, pancreatitis, or corticosteroid use.

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Comment by Dr. Krishna Kumari Challa on April 10, 2025 at 11:37am

Research leads to designation of new type of diabetes: Type 5

Malnutrition-related diabetes—typically affecting lean, malnourished teens and young adults in low- and middle-income countries—is now officially recognized as a distinct form of the disease, known as type 5 diabetes.

Diabetes that is caused by obesity, known as type 2 diabetes, accounts for the majority of diabetes cases in developing countries. But increasingly young people are being diagnosed with diabetes caused not by too much food but by too little—by malnutrition, in other words. Type 5 diabetes is estimated to affect 20-to-25 million people worldwide, mainly in Asia and Africa.

Doctors are still unsure how to treat these patients, who often don't live for more than a year after diagnosis.

**

Comment by Dr. Krishna Kumari Challa on April 10, 2025 at 11:33am

Handheld electro-shockers can pose risk for individuals with cardiac implants, study finds

Research has found that handheld electro-shockers commonly used for self-defense can potentially interact with cardiac implantable electronic devices (CIEDs) such as pacemakers, putting individuals at risk.

The study in Heart Rhythm shows that the individual interactive risk is primarily based on the applied voltage, but also on the manufacturer and type of implanted CIED.

The use of TASER pistols by security forces has been controversial because of associated health risks for subjects receiving a TASER shock. In contrast to TASER pistols, which shoot electrical darts over a distance of up to 10 meters and transmit electrical currents through large parts of a person's body, a handheld electro-shocker delivers energy superficially by directly applying the device to a target.

The handheld electro-shockers tested in this study are legal to own and carry in most countries and therefore, patients with CIEDs might have an increased risk of coming into contact with these devices. This is the first time a study has evaluated the effects of these electro-shockers on CIEDs.

Effects of handheld electro-shockers on cardiac implantable electronic devices, Heart Rhythm (2025). DOI: 10.1016/j.hrthm.2025.02.025

Comment by Dr. Krishna Kumari Challa on April 10, 2025 at 11:24am

Study finds pet dogs pose significant threat to wildlife and ecosystems

New research into the overlooked environmental impact of pet dogs has found far-reaching negative effects on wildlife, ecosystems and climate.

While ecological damage caused by cats has been extensively studied, the new research found dogs, as the world's most common large carnivores, present a significant and multifaceted environmental threat.

The paper, "Bad Dog? The environmental effects of owned dogs," has been published in Pacific Conservation Biology.

The research found that human-owned, pet dogs disturb and directly harm wildlife, particularly shorebirds, even when leashed.

As well as predatory behavior like chasing wildlife, dogs leave scents, urine and feces, which can disrupt animal behavior long after the dogs have left. Studies have found that animals like deer, foxes and bobcats  are less active or completely avoid areas where dogs are regularly walked, even in the absence of the dogs.

Dog waste also contributes to pollution in waterways and inhibits plant growth, while wash-off from chemical treatments used to clean and guard dogs from parasites can add toxic compounds to aquatic environments. In addition, the pet food industry, driven by a vast global dog population, has a substantial carbon, land and water footprint.

Addressing these challenges required a careful balance between reducing environmental harm and maintaining the positive role of dogs as companions and working animals, say the researchers.

The sheer number of pet dogs globally, combined with uninformed or lax behaviors by some owners, is driving environmental issues that we can no longer ignore.

Bad Dog? The environmental effects of owned dogs, Pacific Conservation Biology (2025). doi.org/10.1071/PC24071

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