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Comment by Dr. Krishna Kumari Challa on September 18, 2023 at 9:26am

Matter found to comprise 31% of the total amount of matter and energy in the universe

One of the most interesting and important questions in cosmology is, "How much matter exists in the universe?" An international team of scientists has now succeeded in measuring the total amount of matter for the second time. Reporting in The Astrophysical Journal, the team determined that matter makes up 31% of the total amount of matter and energy in the universe, with the remainder consisting of dark energy.

Cosmologists think that only about 20% of the total matter is made of regular or 'baryonic' matter, which includes stars, galaxies, atoms, and life. About 80% is made of dark matter, whose mysterious nature is not yet known but may consist of some as-yet-undiscovered subatomic particles.

The team used a well-proven technique to determine the total amount of matter in the universe, which is to compare the observed number and mass of galaxy clusters per unit volume with predictions from numerical simulations.

The number of clusters observed at the present time, the so-called 'cluster abundance,' is very sensitive to cosmological conditions and, in particular, the total amount of matter. A higher percentage of the total matter in the universe would result in more clusters being formed. But it is difficult to measure the mass of any galaxy cluster accurately as most of the matter is dark, and we cannot see it directly with telescopes.

To overcome this difficulty, the team was forced to use an indirect tracer of cluster mass. They relied upon the fact that more massive clusters contain more galaxies than less massive clusters (mass richness relation: MRR). Because galaxies consist of luminous stars, the number of galaxies in each cluster can be utilized as a way of indirectly determining its total mass.

By measuring the number of galaxies in each cluster in their sample from the Sloan Digital Sky Survey, the team was able to estimate the total mass of each of the clusters. They were then able to compare the observed number and mass of galaxy clusters per unit volume against predictions from numerical simulations.

The best-fit match between observations and simulations was with a universe consisting of 31% of the total matter, a value that was in excellent agreement with that obtained using cosmic microwave background (CMB) observations from the Planck satellite. Notably, CMB is a completely independent technique.

They have succeeded in making the first measurement of matter density using the MRR, which is in excellent agreement with that obtained by the Planck team using the CMB method.

This work further demonstrates that cluster abundance is a competitive technique for constraining cosmological parameters and complementary to non-cluster techniques such as CMB anisotropies, baryon acoustic oscillations, Type Ia supernovae, or gravitational lensing.

 Mohamed H. Abdullah et al, Constraining Cosmological Parameters Using the Cluster Mass–Richness Relation, The Astrophysical Journal (2023). DOI: 10.3847/1538-4357/ace773

Comment by Dr. Krishna Kumari Challa on September 17, 2023 at 12:45pm

World falling dangerously short of climate goals: UN

A world facing catastrophic climate change is perilously off course in meeting goals for slashing carbon pollution and boosting finance for the developing world, according to the UN's first official progress report out Friday.

The 2015 Paris treaty has successfully driven climate action, but "much more is needed now on all fronts," said the report, which will underpin a crucial climate summit in Dubai at the end of the year.

"The world is not on track to meet the long-term goals of the Paris Agreement," including capping global warming at 1.5 degrees Celsius above mid-19th century levels, the report said.

Achieving net zero carbon emissions by 2050—another Paris goal—will also require phasing out the burning of all fossil fuels whose emissions cannot be captured or compensated.

The stocktake report also says that clean power must be dramatically ramped up, according to the first UN scorecard of the world's progress in meeting Paris Agreement climate goals.

"Scaling up renewable energy and phasing out all unabated fossil fuels are indispensable elements of just energy transitions to net zero emissions," it said.

"Unabated" refers to the absence of any technology that removes carbon emissions, either at the source or from the atmosphere.

Emissions have already peaked in developed and a few developing countries, but are continuing to rise in many of the world's largest economies.

The global stocktake report is a call for radical and immediate action to meet the goals of the Paris Agreement. 

The stocktake also highlights the need to rapidly and radically scale up financial support to developing nations so they can adapt to climate amplified weather disasters that are already eating away at their economies.

Source: News Agencies

Comment by Dr. Krishna Kumari Challa on September 17, 2023 at 12:29pm

Why bats carry viruses that have higher fatality rates in humans than those from other mammals

A small team of biologists and evolutionists reports why bats carry viruses that cause higher fatality rates when jumping to humans than those that come from any other mammal. In their study, reported on the open-access site PLOS Biology, the group used data from past research efforts to model the growth of viruses within bat populations as well as their spread to other animals.

Prior research has shown that when a virus jumps from bats to humans, the results can be deadlier for humans than when viruses jump from other mammals. The reason has been a matter of debate.

In this new effort, the team used data from prior research efforts, along with mathematics and modeling, to show that it is due to an innate tolerance for inflammation in bats, which, the researchers suggest, arose with their ability to fly.

To come to this conclusion, the research team first obtained data from other studies about the impact of several viruses on the immune systems of bats that had also jumped to humans. They then used that data in a mathematical model to show how a virus optimizes its chances of survival (by spreading from host to host before a host dies) by balancing transmission gains with degree of virulence. They found that a key feature of bat physiology—its ability to fly—was related to its tolerance for inflammation. This was pertinent because it made the bat more tolerant of viruses when infected. That allowed for a high growth rate of viruses in bats. And that, the researchers point out, is why the same virus would be more deadly in humans—we have a lower tolerance for inflammation. A lower tolerance, they note, leads to more grave symptoms, such as lungs that are no longer able to process enough air.

The research team extended their study to include 19 other mammals as a way to predict viral growth and the likely impact of a jump to humans in a general sense. They found reason to think that there is a low probability of a lethal virus that spreads easily from bats or other mammals to humans.

 Cara E. Brook et al, Reservoir host immunology and life history shape virulence evolution in zoonotic viruses, PLOS Biology (2023). DOI: 10.1371/journal.pbio.3002268

Comment by Dr. Krishna Kumari Challa on September 16, 2023 at 9:54am

Notorious fungus Aspergillus fumigatus completely scrambles its genome after just one bout of sex

 Researchers have found that Aspergillus fumigatus produces more meiotic crossovers than any other organism. This means that the fungus can establish its complex resistance mechanism after just one cycle of sexual reproduction. The discovery uncovers a possible cause of the rapid spread of hard-to-treat fungal infections.

It also makes it difficult to identify the source of an infection with a resistant fungus. 

Aspergillus fumigatus is naturally widespread in our environment. In fact, we inhale the spores of this fungus every day. For healthy people, this causes no problems. But it can be dangerous for seriously ill patients.

For example, it's risky for people who are in the ICU, or receiving chemotherapy, or those who have undergone an organ transplant. Infections caused by Aspergillus fumigatus are therefore treated medically with azoles, which are antifungal agents. The problem is that the fungus is increasingly resistant to this treatment, and this can be fatal to patients.

One of the causes of the resistance mechanism in the fungus is believed to be the frequent use of azoles in agriculture. Farmers and horticulturists may not use azoles specifically to combat Aspergillus fumigatus, but they do use them to tackle other fungi. Exposure to azoles has enabled Aspergillus fumigatus to develop a resistance mechanism. Compost heaps, where the fungus naturally thrives, are particular hotspots for resistance selection. And that eventually works its way into hospitals. Even patients who have never been treated with an azole can already be carrying an azole-resistant fungus.

There are isolates that have many  genetic differences to those of the fungus at the farm, but also many similarities. This may be due to the sexual reproduction of the fungus, which the researchers looked at in their PLoS Biology study.

The researchers  focused on the number of crossovers per chromosome. In humans, that would be three to four on average. This results in combinations of genes from either parent remaining strongly linked. But in Aspergillus fumigatus, they detected up to 30 crossovers. That's the highest number ever found in an organism.

This means that a single act of sexual reproduction leads to a 'complete reshuffling' of the genome—the genetic makeup of the organism. "This causes enormous variation in the population, even within a relatively limited environment.

It makes it very difficult to identify the transmission route of an infection, from the environment to a patient. The fungus can also efficiently reproduce asexually as well as sexually. So you could simultaneously find the fungus with identical genomes in isolates located thousands of kilometers apart. That makes it very challenging to figure out the transmission of this fungus.

Ben Auxier et al, The human fungal pathogen Aspergillus fumigatus can produce the highest known number of meiotic crossovers, PLOS Biology (2023). DOI: 10.1371/journal.pbio.3002278

Comment by Dr. Krishna Kumari Challa on September 16, 2023 at 9:47am

The bottleneck, potentially caused by a period of global cooling, continued until 813,000 years ago, the study said.

Then there was a population boom, possibly sparked by a warming climate and "control of fire", it added.

The researchers suggested that inbreeding during the bottleneck could explain why humans have a significantly lower level of genetic diversity compared to many other species.

The population squeeze could have even contributed to the separate evolution of Neanderthals, Denisovans and modern humans, all of which are thought to have potentially split from a common ancestor roughly around that time, the study suggested.

It could also explain why so few fossils of human ancestors have been found from the period.

However, archaeologists have pointed out that some fossils dating from the time have been discovered in Kenya, Ethiopia, Europe and China, which may suggest that our ancestors were more widespread than such a bottleneck would allow.
The hypothesis of a global crash does not fit in with the archaeological and human fossil evidence.
In response, the study's authors said that hominins then living in Eurasia and East Asia may not have contributed to the ancestry of modern humans.

"The ancient small population is the ancestor of all modern humans. Otherwise we would not carry the traces in our DNA.
Some experts are "extremely skeptical" that the researchers had accounted for the statistical uncertainty involved in this kind of analysis. They said it will "never be possible" to use genomic analysis of modern humans to get such a precise number as 1,280 from that long ago, emphasizing that there are normally wide ranges of estimations in such research.

The authors of the paper said their range was between 1,270 and 1,300 individuals—a difference of just 30.
But sceptics say that the paper was unconvincing".

Our ancestors may have neared extinction at some point but the ability of modern genomic data to infer such an event was "very weak"they say.

"It's probably one of those questions that we're not going to answer in the near future."
Source: AFP

Part 2

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Comment by Dr. Krishna Kumari Challa on September 16, 2023 at 9:43am

Skepticism about claim human ancestors nearly went extinct

Could the lives of the eight billion people currently on Earth have depended on the resilience of just 1,280 human ancestors who very nearly went extinct 900,000 years ago?

That is the finding of a recent study which used genetic analysis modeling to determine that our ancestors teetered on the brink of annihilation for nearly 120,000 years.

However, scientists not involved in the research have criticized the claim, one telling AFP there was "pretty much unanimous" agreement among population geneticists that it was not convincing.
None denied that the ancestors of humans could have neared extinction at some point, in what is known as a population bottleneck.

But experts expressed doubts that the study could be so precise, given the extraordinarily complicated task of estimating population changes so long ago, and emphasized that similar methods had not spotted this massive population crash.

It is extremely difficult to extract DNA from the few fossils of human relatives dating from more than a couple of hundred thousand years ago, making it hard to know much about them.

But advances in genome sequencing mean that scientists are now able to analyze genetic mutations in modern humans, then use a computer model that works backwards in time to infer how populations changed—even in the distant past.

The study, published in the journal Science earlier this month, looked at the genomes of more than 3,150 modern-day humans.

The Chinese-led team of researchers developed a model to crunch the numbers, which found that the population of breeding human ancestors shrank to about 1,280 around 930,000 years ago.

99 percent of ancestors wiped out?
"About 98.7 percent of human ancestors were lost" at the start of the bottleneck.
Part 1

Comment by Dr. Krishna Kumari Challa on September 15, 2023 at 11:06am

Rivers are rapidly warming, losing oxygen: Aquatic life at risk, study finds

Rivers are warming and losing oxygen faster than oceans, according to a  study published in the journal Nature Climate Change. The study shows that of nearly 800 rivers, warming occurred in 87% and oxygen loss occurred in 70%.

The study also projects that within the next 70 years, river systems, especially in the American South, are likely to experience periods with such low levels of oxygen that the rivers could "induce acute death" for certain species of fish and threaten aquatic diversity at large.

Scientists know that a warming climate has led to warming and oxygen loss in oceans, but did not expect this to happen in flowing, shallow rivers. They found that rivers are warming up and deoxygenating faster than oceans, which could have serious implications for aquatic life—and the lives of humans. 

Widespread deoxygenation in warming rivers, Nature Climate Change (2023). DOI: 10.1038/s41558-023-01793-3

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Electrons from Earth may be forming water on the moon

A team of researchers, led by a University of Hawai'i (UH) at Mānoa planetary scientist, discovered that high energy electrons in Earth's plasma sheet are contributing to weathering processes on the moon's surface and, importantly, the electrons may have aided the formation of water on the lunar surface. The study was published in Nature Astronomy.

Comment by Dr. Krishna Kumari Challa on September 15, 2023 at 10:55am

Selective removal of aging cells opens new possibilities for treating age-related diseases

A research team  has achieved a significant breakthrough in the treatment of age-related diseases. Their cutting-edge technology offers a promising new approach by selectively removing aging cells, without harming normal healthy cells. This groundbreaking development is poised to redefine the future of health care and usher in a new era of targeted therapeutic interventions.

Aging cells, known as senescent cells, contribute to various inflammatory conditions and age-related ailments as humans age. To address this issue, the research team focused on developing a technology that could precisely target and eliminate aging cells, while sparing normal healthy cells. In their study, the team designed organic molecules that selectively target receptors overexpressed in the membranes of aging cells. By leveraging the higher levels of reactive oxygen species (ROS) found in aging cells, these molecules promote the formation of disulfide bonds and create oligomers that bind together. The research is published in the Journal of the American Chemical Society.

Through self-assembly of these oligomers, the researchers successfully created artificial proteins with a stable α-helix secondary structure. These protein-like nanoassemblies exhibited strong binding affinity to the mitochondrial membranes of aging cells, leading to membrane disruption and subsequent cell self-destruction.

"The selective removal of aging cells by targeting the mitochondria and inducing dysfunction has been successfully demonstrated in their experiments. This approach represents a new paradigm for treating age-related diseases.

This innovative technology offers several advantages, including minimal toxicity concerns and a wide therapeutic window by specifically targeting organelles within cells. It opens up exciting possibilities for designing preclinical and clinical trials in the future.

Sangpil Kim et al, Supramolecular Senolytics via Intracellular Oligomerization of Peptides in Response to Elevated Reactive Oxygen Species Levels in Aging Cells, Journal of the American Chemical Society (2023). DOI: 10.1021/jacs.3c06898

Comment by Dr. Krishna Kumari Challa on September 14, 2023 at 11:32am

Expansion Rate: The Hubble Tension

Comment by Dr. Krishna Kumari Challa on September 14, 2023 at 11:09am

Exposure to One Metal May Cause More Heart Disease Than Smoking or Cholesterol

Lead poisoning has a far greater impact on global health than previously thought, potentially contributing to over five million deaths a year and posing a similar threat to air pollution, modelling research suggested recently. The study, described as "a wake-up call", also estimated that exposure to the toxic metal causes young children in developing countries to lose an average of nearly six IQ points each. Lead pollution has been shown to cause a range of serious health problems, particularly relating to heart disease and the brain development of small children, resulting in leaded gasoline being banned worldwide. But people can still be exposed to the potent neurotoxin via food, soil, cookware, fertilisers, cosmetics, lead–acid car batteries and other sources. The researchers' model estimates that 5.5 million adults died from heart disease in 2019 because of lead exposure, 90 percent of them in low- and middle-income countries. That is six times higher than the previous estimate, and represents around 30 percent of all deaths from cardiovascular disease – the leading cause of death worldwide. It would mean that lead exposure is a bigger cause of heart disease than smoking or cholesterol.

https://www.businesswire.com/news/home/20230911634611/en/Pure-Earth....

https://www.thelancet.com/journals/lanplh/article/PIIS2542-5196(23)00166-3/fulltext

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