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Comment by Dr. Krishna Kumari Challa on June 30, 2023 at 11:08am

The NANOGrav 15-year Data Set: Evidence for a Gravitational-Wave Background, The Astrophysical Journal Letters (2023). DOI: 10.3847/2041-8213/acdac6

Gabriella Agazie et al, The NANOGrav 15 yr Data Set: Observations and Timing of 68 Millisecond Pulsars, The Astrophysical Journal Letters (2023). DOI: 10.3847/2041-8213/acda9a

Gabriella Agazie et al, The NANOGrav 15 yr Data Set: Detector Characterization and Noise Budget, The Astrophysical Journal Letters (2023). DOI: 10.3847/2041-8213/acda88

Adeela Afzal et al, The NANOGrav 15 yr Data Set: Search for Signals from New Physics, The Astrophysical Journal Letters (2023). DOI: 10.3847/2041-8213/acdc91

Astrophysical Interpretation of a Gravitational Wave Background from Massive Black Hold Binaries (accepted for publication in ApJL)

Bayesian Limits on GWs from Individual SMBHBs (accepted for publication in ApJL)

Part 2

Comment by Dr. Krishna Kumari Challa on June 30, 2023 at 11:08am

Clamor of gravitational waves from universe's merging supermassive black holes 'heard' for first time

Following 15 years of data collection in a galaxy-sized experiment, scientists have "heard" the perpetual chorus of gravitational waves rippling through our universe for the first time—and it's louder than expected.

The groundbreaking discovery was made by scientists with the North American Nanohertz Observatory for Gravitational Waves (NANOGrav) who closely observed stars called pulsars that act as celestial metronomes. The newly detected gravitational waves—ripples in the fabric of space-time—are by far the most powerful ever measured: They carry roughly a million times as much energy as the one-off bursts of gravitational waves from black hole and neutron star mergers detected by experiments such as LIGO and Virgo.

Most of the gigantean gravitational waves are probably produced by pairs of supermassive black holes spiraling toward cataclysmic collisions throughout the cosmos, the NANOGrav scientists report in a series of new papers appearing today in The Astrophysical Journal Letters.

This is the first-ever evidence for the gravitational wave background. We've opened a new window of observation on the universe."

The existence and composition of the gravitational wave background—long theorized but never before heard—presents a treasure trove of new insights into long-standing questions, from the fate of supermassive black hole pairs to the frequency of galaxy mergers.

For now, NANOGrav can only measure the overall gravitational wave background rather than radiation from the individual "singers." 

The gravitational wave background is about twice as loud as what scientists expected. It's really at the upper end of what our models can create from just supermassive black holes.

The deafening volume may result from experimental limitations or heavier and more abundant supermassive black holes. But there's also the possibility that something else is generating powerful gravitational waves.

Part 1

Comment by Dr. Krishna Kumari Challa on June 28, 2023 at 11:54am

What BMI doesn't tell you about your health

Comment by Dr. Krishna Kumari Challa on June 27, 2023 at 10:27am

Liver fibrosis linked to reduced cognitive ability and brain volume

Researchers have found that liver fibrosis — scarring of the liver tissue that occurs in many chronic liver diseases — is associated with reduce cognitive ability and, in certain regions of the brain, reduced brain volume. And this connection may be mediated in part by inflammation.

The researchers evaluated data on liver fibrosis, cognitive function — such as working memory, the ability to solve new problems, and processing speed — and gray matter volume in different regions of the brain. They found that, compared with healthy participants, those with liver fibrosis tended to have reduced cognitive ability and reduced gray matter volume in several brain regions, including the hippocampus, thalamus, striatum, and brain stem.

With this type of study, the researchers could not establish cause and effect; they could only evaluate correlations.

A growing body of scientific evidence is revealing that brain health and body health are interconnected, such that one often affects the other. 
More and more, people are starting to realize that there’s not this split between brain-based disorders and other types of physical health. We’re starting to understand that liver disease, heart disease, and other diseases will have impacts on the brain, and brain disorders have impacts on the body

https://www.sciencedirect.com/science/article/pii/S235239642300244X

Comment by Dr. Krishna Kumari Challa on June 27, 2023 at 9:57am

A Hole in the World
There’s a hole under the Indian Ocean. Spanning more than three million square kilometers, the gouge is centered about 1,200 km southwest of the southern tip of India. Because of a low pull of gravity there, combined with higher gravity in surrounding areas, the sea level over the hole is 106 meters lower than the global average, according to a new study.

Why this is cool: Earth is not perfectly round. Rather, it is flatter at the poles and bulges around the equator, with other irregular peaks and valleys caused by different regions’ mass exerting different gravitational pulls. The hole under the Indian Ocean is the planet's most prominent gravitational anomaly.

What the experts say: Slabs of the floor of an ancient sea called the Tethys Ocean which existed 200 million years ago sank into the mantle, creating plumes of molten rock. The hole under the Indian Ocean probably took its present shape about 20 million years ago, when the plumes started to spread within the upper mantle, says Debanjan Pal, a doctoral student at the Indian Institute of Science in Bangalore, and lead author of the new study.

https://eos.org/science-updates/seismologists-search-for-the-indian...

https://www.scientificamerican.com/article/giant-gravity-hole-in-th...

Comment by Dr. Krishna Kumari Challa on June 26, 2023 at 12:54pm

In fact, as far back as 1995, researchers were arguing that babies born with both 'true' and 'pseudo' tails should undergo neuroimaging as well as surgery to make sure their development was tracking like it should.

So why have vestigial tails been reported in case studies since as though they were innocent, undisputed consequences of our genetic heritage?

Part of the problem is that it is not yet known if a true tail is directly derived from the embryonic tail, as some scientists have suggested. There simply isn't enough research on where the congenital abnormality lies – partly because of how rare these case studies are.

Regardless of where a baby's tail came form, however, evidence strongly suggests it is the result of a congenital issue and is not a harmless vestigial trait.

For the life and health of these children, that's an important message that needs to be cleared up once and for all.

Part 3

**

https://www.sciencealert.com/some-babies-are-born-with-tails-but-no...

Comment by Dr. Krishna Kumari Challa on June 26, 2023 at 12:53pm

As it turns out, both rare appendages probably represent an incomplete fusion of the spinal column, or what's known as a spinal dysraphism. This suggests their formation is not a harmless 'regression' in the evolutionary process but a concerning disturbance in an embryo's growth most likely resulting from a mix of genetic and environmental factors.

When a human embryo reaches about five weeks of development, it sprouts a tail-like structure composed of a neural tube and notochord, which is kind of like an early spinal cord.

By the eighth week of development, this tail is typically reabsorbed back into the embryo's body. If it sticks around until birth, it could indicate the presence of a larger birth defect.

In fact, human babies that are born with tails tend to have serious associated neurological defects. In 2008, for instance, a paper argued that "true vestigial tails are not benign" because they may be associated with underlying dysraphism.

Roughly half of the cases reviewed were associated with either meningocele or spina bifida occulta.

This suggests babies born with tails need greater medical attention than a simple surgery. And it strongly disagrees with the 1985 paper that argued "the true human tail is a benign condition not associated with any underlying [spinal] cord malformation."

Part 2

Comment by Dr. Krishna Kumari Challa on June 26, 2023 at 12:52pm

Some Babies Are Born With 'Tails'

 In very rare cases, humans can be born with boneless rear-end appendages, sometimes up to 18 centimeters long. To date, official records have tallied about 40 babies born with 'true tails', consisting of soft, boneless, finger-like protrusions that are easily removed via surgery.

Nevertheless, the rare case studies tend to generate "an unusual amount of interest, excitement and anxiety", according to researchers. Often, this is because the 'tails' are conisidered to be benign, evolutionary remnants of a long lost ancestor.

As it turns out, that's based on an outdated theory that has been contentious for decades now. The reality for these children may be much darker, and they deserve medical attention, not our morbid fascination.

The appendages some babies are born with have historically been deemed 'true' or 'vestigial' tails. But that's a bit of a misnomer, as they aren't really like any other tail known in nature. They typically don't contain bones, cartilage, or a spinal cord. They just kind of hang there without a clear function.

Still, that doesn't mean these appendages are as harmless as scientists used to think.

The misunderstanding over the tail's origin starts with Charles Darwin himself. Over a century ago, Darwin proposed that human vestigial tails are evolutionary accidents, or rudimentary leftovers from a primate ancestor that was once tailed itself.

In the 1980s, scientists took this theory and ran with it. They argued that a genetic mutation, evolved by humans to erase our tails, could sometimes revert back to its ancestral state.

In 1985, a seminal paper defined two different types of 'tails' that human babies can be born with. The first, as mentioned before, is a vestigial or true tail, originally thought to be inherited from our ancestors.

But another type of outgrowth from the tailbone, which sometimes does include bone, is known as a 'pseudotail'.

Historically, the pseudotail has been the one associated with birth defects, and as such, it is not considered vestigial.

Part 1

Comment by Dr. Krishna Kumari Challa on June 26, 2023 at 12:24pm

Understanding Earth gives us the means to better protect it.

Comment by Dr. Krishna Kumari Challa on June 24, 2023 at 10:17am

All the immunity, none of the symptoms, through dietary intervention

Worldwide, more than a million deaths occur each year due to diarrheal diseases that lead to dehydration and malnutrition. Yet, no vaccine exists to fight or prevent these diseases, which are caused by bacteria like certain strains of E. coli. Instead, people with bacterial infections must rely on the body taking one of two defense strategies: kill the intruders or impair the intruders but keep them around. If the body chooses to impair the bacteria, then the disease can occur without the diarrhea, but the infection can still be transmitted—a process called asymptomatic carriage.

Now,  scientists have found that pairing specific diets with disease-causing bacteria can create lasting immunity in mice without the costs of developing sickness, revealing a new potential vaccination strategy. Their findings, published in Science Advances on June 23, 2023, pave the way for the development of new vaccines that could promote immunity for those with diarrheal diseases and possibly other infections.

They  discovered that immunization against diarrheal infections is possible if they allow the bacteria to retain some of its disease-causing behaviour.

Researchers looked at how dietary interventions can create an asymptomatic infection, which they call a cooperative relationship between bacteria and host (the person or animal that the bacteria have infected) where the host does not experience any symptoms. They discovered that an iron-rich diet enabled mice to survive a normally lethal bacterial infection without ever developing signs of sickness or disease.

The high-iron diet increased unabsorbed sugar (glucose) in the mice's intestines, which the bacteria could feast on. The excess sugar served as a "bribe" for the bacteria, keeping them full and incentivized to not attack the host.

This process produced long-term asymptomatic infection with the bacteria, leading the researchers to think that the adaptive immune system (cells and proteins that "remember" infections) may be involved.

Grischa Chen et al, Cooperation between physiological defenses and immune resistance produces asymptomatic carriage of a lethal bacterial pathogen, Science Advances (2023). DOI: 10.1126/sciadv.adg8719. www.science.org/doi/10.1126/sciadv.adg8719

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