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Comment by Dr. Krishna Kumari Challa on August 11, 2022 at 12:48pm

Rainwater unsafe to drink due to chemicals: study

Rainwater everywhere on the planet is unsafe to drink due to levels of toxic chemicals known as PFAS that exceed the latest guidelines, according to a new study by scientists.

Commonly known as 'forever chemicals' because they disintegrate extremely slowly, PFAS (per- and polyfluoroalkyl substances) were initially found in packaging, shampoo or makeup but have spread to our entire environment, including water and air.

There is nowhere on Earth where the rain would be safe to drink, according to the measurements that scientists have taken now.

Even in Antarctica or the Tibetan plateau, the levels in the rainwater are above the drinking water guidelines that the US EPA (Environmental Protection Agency) proposed.

According to some studies, exposure can also lead to problems with fertility, development delays in children, increased risks of obesity or certain cancers (prostate, kidney and testicular), an increase in cholesterol levels.
—Planet 'irreversibly contaminated'—

We have made the planet inhospitable to human life by irreversibly contaminating it now so that nothing is clean anymore. And to the point that's it's not clean enough to be safe.

We have crossed a planetary boundary. And we have to learn to live with it.

 Per- and polyfluoroalkyl substances (PFAS) define a new planetary boundary for novel entities that has been exceeded, Environmental Science & Technology (2022). DOI: 10.1021/acs.est.2c02765

Comment by Dr. Krishna Kumari Challa on August 11, 2022 at 8:49am

Methane satellites find landfills with the same climate impact as several hundred thousand cars

Methane is almost thirty times more powerful as a greenhouse gas than CO₂. Researchers from SRON Netherlands Institute for Space Research therefore scan the entire globe for large methane leaks. A landfill in Buenos Aires turns out to emit tens of tons of methane per hour, comparable to the climate impact of one and a half million cars. They also detect large emissions from landfills in India and Pakistan, identifying new low-hanging fruit in the battle against climate change. The work was published on August 10 in Science Advances.

Methane is the second largest anthropogenic contributor to the greenhouse effect, after CO₂. This is due to its large global warming potential over 100 years (GWP-100). Methane is almost 30 times more potent per ton as a greenhouse gas than CO₂. When methane is released through human activity—by oil installations, coal mines, cattle sheds or landfills—it can be made less harmful by flaring it and thereby converting it to CO₂. Even better, if you capture it, you can put it to good use in boilers or stoves. Researchers from SRON Netherlands Institute for Space Research have now used satellite data to locate a number of landfills that are low-hanging fruit in the fight against climate change. Four landfills in Argentina, India and Pakistan emit several or even tens of tons of methane per hour.

 Buenos Aires, Delhi, Lahore and Mumbai stood out, with urban emissions on average twice as high as estimated in global inventories. The landfill in Buenos Aires emits 28 tons of methane per hour, comparable to the climate impact of 1.5 million cars. The three other landfills are responsible for, respectively, three, six and 10 tons of methane per hour, which still amounts to the impact of 130,000 to 500,000 cars.

Methane is odorless and colorless, so leaks are notoriously difficult to detect. But satellites are ideally suited for this. Landfills are super-emitters that pump large amounts of methane into the atmosphere. That is painful to watch because you can solve it with relatively little effort. You could, for example, separate and compost the organic waste, which would drastically reduce methane production. And even in the case of mixed waste, you can still collect or flare the methane produced. Methane has a lifetime of only about 10 years in the atmosphere, so if we act now, we will quickly see results in the form of less global warming.

Joannes D. Maasakkers, Daniel J. Varon, Aldís Elfarsdóttir, Jason McKeever, Dylan Jervis, Gourav Mahapatra, Sudhanshu Pandey, Alba Lorente, Tobias Borsdorff, Lodewijck R. Foorthuis, Berend J. Schuit, Paul Tol, Tim A. van Kempen, Richard van Hees, Ilse Aben, 'Using satellites to uncover large methane emissions from landfills', Science Advances, 2022. science.org/doi/10.1126/sciadv.abn9683

Comment by Dr. Krishna Kumari Challa on August 11, 2022 at 8:40am

Watch tiny electromechanical robots that are faster than cheetahs for their size

Comment by Dr. Krishna Kumari Challa on August 9, 2022 at 9:24am

Mystery cells that create blood stem cells in mammals identified

Imagine if one day blood transfusions from strangers were not needed because they could be produced from cells that line your own blood vessels' cells.

While that day is still some years off, medical researchers at UNSW Sydney have made an important first step by identifying—in mice—a mechanism that is used naturally in mammals to make blood from cells that line blood vessels.

It was already known that a process termed "endothelial to hematopoietic transition" takes place in mammalian embryos, whereby cells lining blood vessels (endothelial cells) change into blood stem cells.

But the identity of the cells that regulate this process had up until now been a mystery.

In a paper published recently in the journal Nature Cell Biology, a team of researchers describe how they solved this puzzle by identifying the cells in the embryo that can convert adult endothelial cells into blood stem cells. The cells—known as "Mesp1-derived PDGFRA+ stromal cells"—reside underneath the aorta.

While more research is needed before this can be translated into clinical practice, the discovery could be an important step in regenerative medicine by providing a potential new tool to generate engraftable hematopoietic stem cells.

Vashe Chandrakanthan et al, Mesoderm-derived PDGFRA+ cells regulate the emergence of hematopoietic stem cells in the dorsal aorta, Nature Cell Biology (2022). DOI: 10.1038/s41556-022-00955-3

Comment by Dr. Krishna Kumari Challa on August 9, 2022 at 9:15am

Chances of climate catastrophe are ignored, scientists say

Experts are ignoring the worst possible climate change catastrophic scenarios, including collapse of society or the potential extinction of humans, however unlikely, a group of top scientists claim.

Eleven scientists from around the world are calling on the United Nations' Intergovernmental Panel on Climate Change, the world's authoritative climate science organization, to do a special science report on "catastrophic climate change" to "bring into focus how much is at stake in a worst-case scenario." In their perspective piece in Monday's Proceedings of the National Academy of Sciences they raise the idea of human extinction and worldwide societal collapse in the third sentence, calling it "a dangerously underexplored topic."

The scientists said they aren't saying that worst is going to happen. They say the trouble is no one knows how likely or unlikely a "climate endgame" is and the world needs those calculations to battle global warming.

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Comment by Dr. Krishna Kumari Challa on August 9, 2022 at 8:45am

Dry lightning is cloud-to-ground (CG) lightning without any accompanied rainfall nearby.

Dry lightning sparks some of the most destructive and costly wildfires in California, study finds

A new study has found dry lightning outbreaks are the leading cause of some of the largest wildfire outbreaks in modern California history.

Researchers have developed the first long-term climatology of dry lightning—lightning which occurs with less than 2.5 mm of rainfall.

They found that moisture and instability high in the atmosphere—above a hot, dry, lower atmosphere—were key drivers of dry lightning across all regions in central and northern California and that widespread dry lightning outbreaks can occur anytime between May–October, even in "quiet" years for lightning activity.

Meteorological and geographical factors associated with dry lightning in central and northern California, Environmental Research: Climate (2022) DOI: 10.1088/2752-5295/ac84a0

https://phys.org/news/2022-08-lightning-destructive-costly-wildfire...

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Comment by Dr. Krishna Kumari Challa on August 9, 2022 at 8:34am

Robotic motion in curved space defies standard laws of physics

When humans, animals, and machines move throughout the world, they always push against something, whether it's the ground, air, or water. Until recently, physicists thought this to be a constant, following the law of conservation momentum. Now, researchers have proven the opposite—when bodies exist in curved spaces, it turns out that they can in fact move without pushing against something.

The findings were published in Proceedings of the National Academy of Sciences on July 28, 2022. In the paper, a team of researchers created a robot confined to a spherical surface with unprecedented levels of isolation from its environment, so that these curvature-induced effects would predominate.

The researchers found that as the robot changed its shape, it inched forward around the sphere in a way that could not be attributed to environmental interactions.

The researchers set out to study how an object moved within a curved space. To confine the object on the sphere with minimal interaction or exchange of momentum with the environment in the curved space, they let a set of motors drive on curved tracks as moving masses. They then connected this system holistically to a rotating shaft so that the motors always move on a sphere. The shaft was supported by air bearings and bushings to minimize the friction, and the alignment of the shaft was adjusted with the Earth's gravity to minimize the residual force of gravity.

From there, as the robot continued to move, gravity and friction exerted slight forces on it. These forces hybridized with the curvature effects to produce a strange dynamic with properties neither could induce on their own. The research provides an important demonstration of how curved spaces can be attained and how it fundamentally challenges physical laws and intuition designed for flat space. 

While the effects are small, as robotics becomes increasingly precise, understanding this curvature-induced effect may be of practical importance, just as the slight frequency shift induced by gravity became crucial to allow GPS systems to accurately convey their positions to orbital satellites. Ultimately, the principles of how a space's curvature can be harnessed for locomotion may allow spacecraft to navigate the highly curved space around a black hole.

Also because spacetime is very slightly curved, a device could actually move forward without any external forces or emitting a propellant—a novel discovery.

Shengkai Li et al, Robotic swimming in curved space via geometric phase, Proceedings of the National Academy of Sciences (2022). DOI: 10.1073/pnas.2200924119

Comment by Dr. Krishna Kumari Challa on August 7, 2022 at 1:01pm

Israeli scientists create the world's first 'Artificial Embryos' 

Comment by Dr. Krishna Kumari Challa on August 6, 2022 at 2:59pm

Early-life acquisition of antimicrobial resistance in newborn children from low- and middle-income countries
Every year, almost 7 million potentially serious bacterial infections are estimated to occur in newborns, resulting in more than 550,000 annual neonatal deaths. Most of these infections and deaths happen in LMICs, where often scarce resources can limit the capacity to diagnose and treat sepsis. These problems are further complicated by the global rise of antimicrobial resistance (AMR), particularly the rapid spread of gram-negative bacteria that are resistant to antibiotics—including Klebsiella pneumoniae, Escherichia coli, and Enterobacter cloacae that are no longer susceptible to ß-lactam antibiotics, such as ampicillin and ceftazidime. AMR is already estimated to account for approximately 5 million deaths a year worldwide, and has been predicted to result in 10 million annual deaths by 2050.
Despite neonatal sepsis representing such a major health problem in LMICs, it is still unclear how, when, and where newborn babies acquire life-threatening infections. Furthermore, the factors associated with the presence of AMR in these cases are also still being elucidated. For example, there have been no studies in LMICs examining whether the presence of antibiotic-resistant bacteria in mothers is linked to the development of sepsis in their newborns.

In a new study published in Nature Microbiology, scientists decided to look at the presence of antibiotic resistance genes (ARGs) in the gut microbiota—the collection of microbes that are present in the human gut—of mothers and their babies from 7 LMICs in Africa and South Asia. As part of the "Burden of Antibiotic Resistance in Neonates from Developing Societies" study, or BARNARDS—a network of 12 clinical sites across Bangladesh, Ethiopia, India, Nigeria, Pakistan, Rwanda and South Africa—they recruited 35,040 mothers and 36,285 neonates. From these, they collected 18,148 rectal swabs (15,217 from mothers and 2,931 from neonates, including 626 with sepsis), which were used to grow the bacteria present in these samples and assess the presence of clinically important ARGs in the microbiota of mothers and their babies. The authors found that a large number of samples carried genes linked to antibiotic resistance, suggesting that AMR is far more widespread in these settings than previously anticipated.

For example, samples from around 1 in 5 neonates (18.5%) were positive for blaNDM, a gene that encodes New Delhi metallo-beta-lactamase, which is an enzyme that can destroy ß-lactam antibiotics including the commonly used carbapenems, resulting in the bacteria being resistant against this drug. Importantly, the researchers found that ARGs were present in neonates within hours of birth, indicating that initial colonization of the newborns with antibiotic-resistant bacteria occurred at birth or soon after, likely through contact with the mother or from the hospital environment.

Maria Carvalho, Antibiotic resistance genes in the gut microbiota of mothers and linked neonates with or without sepsis from low- and middle-income countries, Nature Microbiology (2022). DOI: 10.1038/s41564-022-01184-y. www.nature.com/articles/s41564-022-01184-y

Comment by Dr. Krishna Kumari Challa on August 6, 2022 at 2:58pm

Sterile mice produce rat sperm

Researchers generated rat sperm cells inside sterile mice using a technique called blastocyst complementation. The advance appears August 4 in the journal Stem Cell Reports.
This new study shows that scientists can use sterile animals as hosts for the generation of germ cells from other animal species.
Aside from a conceptual advancement, this notion can be utilized to produce endangered animal species gametes inside more prevalent animals. Other implications may involve an improved method to produce rat transgenic models for biomedical research.
Pluripotent stem cells (PSCs) provide a powerful tool for biomedical research, but the generation of gametes in the form of eggs or sperm cells from PSCs is a highly challenging endeavor. In prior studies, researchers used a technique called blastocyst complementation to generate rat organs in mice using PSCs and mutated mouse embryos that cannot produce specific organs. Building on this work, Bar-Nur and his collaborators wondered whether it would be possible to generate rat sperm inside mice that carry a genetic mutation that otherwise renders them sterile.

To test this idea, the researchers injected rat PSCs into mouse embryos to produce mouse-rat chimeras. An essential gene for sperm production was mutated in the mouse blastocysts. The rat stem cells developed together with the mouse cells, thereby generating a chimeric animal composed of genotypes from the two species. As a consequence of the genetic sterility-inducing mutation, an empty niche developed inside the testes, which enabled the rat cells to colonize them and exclusively generate rat sperm in mouse-rat chimeras. The sperm cells could fertilize rat egg cells, but the embryos did not develop normally or give rise to live offspring.

The interesting thing observed in this study was that all the sperm cells inside the chimeras were of rat origin. As such, the mouse host environment, which was sterile due to a genetic mutation, was still able to support efficient sperm cell production from a different animal species.

Although the researchers were able to generate rat sperm cells that morphologically appeared indistinguishable from normal rat sperm cells, these cells were immotile and the fertilization rates of rat eggs was significantly lower in comparison to rat sperm cells produced in rats. Nonetheless, the work provides a proof-of-principle that one can generate sperm cells of one animal species in another by mixing the two species in an artificially generated organism called a chimera. Using sterile mice for genetically modified rat PSCs may speed up the production of transgenic rats to model human diseases in biomedical research.

Ori Bar-Nur, Exclusive generation of rat spermatozoa in sterile mice utilizing blastocyst complementation with pluripotent stem cells, Stem Cell Reports (2022). DOI: 10.1016/j.stemcr.2022.07.005. www.cell.com/stem-cell-reports … 2213-6711(22)00364-2

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