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Comment by Dr. Krishna Kumari Challa on May 15, 2021 at 10:59am

Meteorites - part 2

In total, scientists around the world have collected more than 60,000 meteorites, mostly from desert regions such as Antarctica or Australia's Nullarbor Plain.

We now know most of these come from the main asteroid belt—a region between Mars and Jupiter.

But might some of them have come not from asteroids, but from comets that originated in the outer reaches of the solar system? What would such meteorites be like, and how would we find them?

Fortunately, we can actively look for meteorites, rather than hoping to stumble across one lying on the ground. When a space rock is falling through the atmosphere (at this stage, it's known as a meteor), it begins to heat up and glow—hence why meteors are nicknamed "shooting stars."

Larger meteors (at least tens of centimeters across) glow brightly enough to be termed "fireballs." And by training cameras on the sky to spot them, we can track and recover any resulting meteorites.

The largest such network is the Desert Fireball Network, which features around 50 cameras covering more than 2.5 million square kilometers of the Australian outback.

The network's data has resulted in the recovery of six meteorites in Australia, and two more internationally. What's more, by tracking a fireball's flight through the atmosphere, we can not only project its path forwards to find where it landed, but also backwards to find out what orbit it was on before it got here.

Our research, published in the Planetary Science Journal, scoured every fireball tracked by the DFN between 2014 and 2020, in search of possible cometary meteorites. In total, there were 50 fireballs that came from comet-like orbits not associated with a meteor shower.

Unexpectedly, despite the fact that just under 4% of the larger debris was from comet-like orbits, none of the material featured the hallmark "dirty snowball" chemical composition of true cometary material.

We concluded that debris from comets breaks up and disintegrates before it even gets close to becoming a meteorite. In turn, this means cometary meteorites are not represented among the tens of thousands of objects in the world's meteorite collections.

The next question is: if all meteorites are asteroidal, how did some of them end up in such weird, comet-like orbits?

For this to be possible, debris from the main asteroid belt must have been knocked from its original orbit by a collision, close gravitational encounter, or some other mechanism.

Meteorites have given us our most profound insights into the formation and evolution of our solar system. However, it is now clear that these samples represent only part of the whole picture. It is definitely an argument for a sample-return mission to a comet. It's also testament to the knowledge we can gain from tracking fireballs and the meteorites they sometimes leave behind.

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Comment by Dr. Krishna Kumari Challa on May 15, 2021 at 10:58am

Where do meteorites come from? We tracked hundreds of fireballs streaking through the sky to find out

If asked where meteorites come from, you might reply "from comets." But according to  new research, which tracked hundreds of fireballs on their journey through the Australian skies, you would be wrong.

In fact, it is very likely that all meteorites—space rocks that make it all the way to Earth—come not from icy comets but from rocky asteroids. Our new study found that even those meteorites with trajectories that look like they arrived from much farther afield are in fact from asteroids that simply got knocked into strange orbits.

hat means that of the tens of thousands of meteorites in collections around the world, likely none are from comets, leaving a significant gap in our understanding of the solar system.

When the solar system formed, more than 4.5 billion years ago, a disc of dust and debris was swirling around the Sun.

Over time, this material clumped together, forming larger and larger bodies—some so large they swept up everything else in their orbit, and became planets.

Yet some debris avoided this fate and is still floating around today. Scientists traditionally classify these objects into two groups: comets and asteroids.

Asteroids are rockier and drier, because they were formed in the inner solar system. Comets, meanwhile, formed further out, where ices such as frozen water, methane or carbon dioxide can remain stable—giving them a "dirty snowball" composition.

The best way to understand the origin and evolution of our solar system is to study these objects. Many space missions have been sent to comets and asteroids over the past few decades. But these are expensive, and only two (Hayabusa and Hayabusa2) have successfully brought back samples.

Another way to study this material is to sit and wait for it to come to us. If a piece of debris happens to cross paths with Earth, and is large and robust enough to survive hitting our atmosphere, it will land as a meteorite.

Most of what we know about the solar system's history comes from these curious space rocks. However, unlike space mission samples, we don't know exactly where they originated.

Meteorites have been curiosities for centuries, yet it was not until the early 19th century that they were identified as extraterrestrial. They were speculated to come from lunar volcanoes, or even from other star systems.

Today, we know all meteorites come from small bodies in our solar system. But the big question that remains is: are they all from asteroids, or do some come from comets?

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Part 1

Comment by Dr. Krishna Kumari Challa on May 15, 2021 at 10:51am

Mammals can breathe through anus in emergencies

Rodents and pigs share with certain aquatic organisms the ability to use their intestines for respiration, finds a study . The researchers demonstrated that the delivery of oxygen gas or oxygenated liquid through the rectum provided vital rescue to two mammalian models of respiratory failure.

Artificial respiratory support plays a vital role in the clinical management of respiratory failure due to severe illnesses such as pneumonia or acute respiratory distress syndrome.

Several aquatic organisms have evolved unique intestinal breathing mechanisms to survive under low-oxygen conditions using organs other than lungs or gills. For example, sea cucumbers, freshwater fish called loaches, and certain freshwater catfish use their intestines for respiration. But it has been heavily debated whether mammals have similar capabilities.

In the new study, researchers provide evidence for intestinal breathing in rats, mice, and pigs. First, they designed an intestinal gas ventilation system to administer pure oxygen through the rectum of mice. They showed that without the system, no mice survived 11 minutes of extremely low-oxygen conditions. With intestinal gas ventilation, more oxygen reached the heart, and 75% of mice survived 50 minutes of normally lethal low-oxygen conditions.

Ryo Okabe et al, Mammalian enteral ventilation ameliorates respiratory failure, Med (2021). DOI: 10.1016/j.medj.2021.04.004

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Because the intestinal gas ventilation system requires abrasion of the intestinal muscosa, it is unlikely to be clinically feasible, especially in severely ill patients—so the researchers also developed a liquid-based alternative using oxygenated perfluorochemicals. These chemicals have already been shown clinically to be biocompatible and safe in humans.

The intestinal liquid ventilation system provided therapeutic benefits to rodents and pigs exposed to non-lethal low-oxygen conditions. Mice receiving intestinal ventilation could walk farther in a 10% oxygen chamber, and more oxygen reached their heart, compared to mice that did not receive intestinal ventilation. Similar results were evident in pigs. Intestinal liquid ventilation reversed skin pallor and coldness and increased their levels of oxygen, without producing obvious side effects. Taken together, the results show that this strategy is effective in providing oxygen that reaches circulation and alleviates respiratory failure symptoms in two mammalian model systems.

https://phys.org/news/2021-05-mammals-anus-emergencies.html?utm_sou...

Comment by Dr. Krishna Kumari Challa on May 15, 2021 at 10:46am

Observations show marine clouds amplify warming

A new analysis of satellite cloud observations finds that global warming causes low-level clouds over the oceans to decrease, leading to further warming.

These clouds, such as the stratocumulus clouds responsible for the often gloomy conditions in summers, are widespread over the global oceans and strongly cool the planet by shading the surface from sunlight. The new study finds that, overall, this cooling effect will be modestly reduced as the concentration of carbon dioxide (CO₂) in the atmosphere increases. The warming initially caused by increasing CO₂ gets an extra push from reductions in clouds—an amplifying feedback.

 Timothy A. Myers et al. Observational constraints on low cloud feedback reduce uncertainty of climate sensitivity, Nature Climate Change (2021). DOI: 10.1038/s41558-021-01039-0

S. C. Sherwood et al. An Assessment of Earth's Climate Sensitivity Using Multiple Lines of Evidence, Reviews of Geophysics (2020). DOI: 10.1029/2019RG000678

https://phys.org/news/2021-05-marine-clouds-amplify.html?utm_source...

Comment by Dr. Krishna Kumari Challa on May 14, 2021 at 10:34am

A paradigm shift to combat indoor respiratory infection

Call for 'paradigm shift' to fight airborne spread of COVID-19 indoors

40 researchers from 14 countries in a call published in Science for a shift in standards in ventilation requirements equal in scale to the transformation in the 1800s when cities started organising clean water supplies and centralised sewage systems.

The international group of air quality researchers called on the World Health Organisation to extend the indoor air quality guidelines to include airborne pathogens and to recognise the need to control hazards of airborne transmission of respiratory infections.

https://science.sciencemag.org/content/372/6543/689

 L. Morawska at Queensland University of Technology in Brisbane, Australia el al., "A paradigm shift to combat indoor respiratory infection," Science (2021). science.sciencemag.org/cgi/doi … 1126/science.abg2025

https://phys.org/news/2021-05-paradigm-shift-airborne-covid-indoors...

Comment by Dr. Krishna Kumari Challa on May 14, 2021 at 10:13am

New evidence for electron's dual nature found in a quantum spin liquid

A new discovery led by Princeton University could upend our understanding of how electrons behave under extreme conditions in quantum materials. The finding provides experimental evidence that this familiar building block of matter behaves as if it is made of two particles: one particle that gives the electron its negative charge and another that supplies its magnet-like property, known as spin.

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Causes of concrete and asphalt deterioration explained

Scientists have revealed that the deterioration of modern concrete and asphalt structures is due to the presence of trace quantities of organic matter in these structures.

Comment by Dr. Krishna Kumari Challa on May 14, 2021 at 10:11am

Cancer has ripple effect on distant tissues

A new study with zebrafish shows that a deadly form of skin cancer—melanoma—alters the metabolism of healthy tissues elsewhere in the body. The research from Washington University in St. Louis suggests that these other tissues could potentially be targeted to help treat cancer.

Tumors rely on a constant supply of nutrients to grow. Instead of competing with tumors for nutrients, other tissues can reprogram their metabolism to be complementary. In some instances, this may even allow healthy tissues to feed the tumour. 

The scientists examined tissues in the liver, intestine, fin, muscle, brain, blood, and eye of the zebrafish that has melanoma.. They observed metabolic dysregulation across most of the tissues—indicating that melanoma broadly impacts whole-body metabolism.

Patti, Gary J. et al.: "Isotope tracing in adult zebrafish reveals alanine cycling between melanoma and liver" Cell Metabolism (2021). DOI: 10.1016/j.cmet.2021.04.014 , www.cell.com/cell-metabolism/f … 1550-4131(21)00180-7

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Cancer consumes tremendous amounts of glucose, a key source of energy for cells in the body. Glucose, or blood sugar, is derived from food and transported around the body through the bloodstream after eating. Tumors actively soak up glucose as a fuel to support their rapid growth.

This trait is so well known that physicians regularly use it as a diagnostic test for cancer, where patients are administered a specific form of glucose that can be monitored with a PET scan. What is less clear is how a tumor's penchant for glucose affects other tissues.

"Glucose levels are tightly regulated," Patti said. "When glucose levels get too low, it's dangerous. We wanted to know whether a tumor with a high avidity for glucose might influence glucose levels in the blood."

Even when healthy people go a long period of time without eating, blood glucose levels are kept relatively constant. That is because glucose can be made by the liver when it cannot be obtained directly from food.

As it turns out, the liver counters the impact of the tumor by synthesizing glucose. It's very similar to what occurs during a fast.

 the scientists observed that melanoma tissues in the body consume about 15 times more glucose than the other tissues they measured. Despite this burden, the zebrafish were able to maintain circulating glucose levels, apparently by making glucose in the liver through a process that is ordinarily triggered when we go without eating.

https://medicalxpress.com/news/2021-05-cancer-ripple-effect-distant...

Comment by Dr. Krishna Kumari Challa on May 14, 2021 at 9:55am

Food dyes may cause disease when the immune system is dysregulated, researchers report

Artificial food colorants can cause disease when the immune system has become dysregulated, researchers report. The study, published in Cell Metabolism in May, was the first to show this phenomenon.

The study, conducted in mice, found that the mice developed colitis when they consumed food with the artificial food colorants FD&C Red 40 and Yellow 6 when a specific component of their immune system, known as cytokine IL-23, was dysregulated. While it remains unclear whether food colorants have similar effects in humans, researchers plan to investigate exactly how cytokine IL-23 promotes the development of colitis after food colorant exposure.

Colitis is a form of inflammatory bowel disease (IBD), and cytokine IL-23 dysregulation is known to be a factor in the development of IBD in humans. Medicines that block its function are now successfully used in patients. Food colorants such as Red 40 and Yellow 6 are widely used in food, drink, and medicine. These two food colorants are the most commonly used in the world.

Both genetic predisposition and environmental factors appear to play a role in whether a person develops IBD, a condition that affects millions of people worldwide, but the exact environmental factors have remained elusive.

For the study, the researchers created mouse models that had a dysregulated expression of cytokine IL-23. To their surprise, the mice with the dysregulated immune response did not develop inflammatory bowel disease spontaneously even though dysregulated IL-23 is a factor in people with the disease.

When given a diet with the food dyes Red 40 or Yellow 6, the altered mice developed colitis. However, mice that had the dye-infused diet but had a normal immune system did not develop IBD. To prove that the food colorant was indeed responsible, the researchers fed the altered mice diets without the food colorant and water containing it; in both cases, the disease developed when the mice consumed the colorant, but not otherwise. They repeated this finding for several diets and several food colorants.

The dramatic changes in the concentration of air and water pollutants and the increased use of processed foods and food additives in the human diet in the last century correlate with an increase in the incidence of inflammatory and autoimmune diseases

https://medicalxpress.com/news/2021-05-food-dyes-disease-immune-dys...

https://www.eurekalert.org/pub_releases/2021-05/tmsh-fdm050621.php#...(May%2013,first%20to%20show%20this%20phenomenon.

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Comment by Dr. Krishna Kumari Challa on May 13, 2021 at 12:39pm

Tides Under Ocean’s Surface

Comment by Dr. Krishna Kumari Challa on May 13, 2021 at 11:41am

Study of ancient corals in Indonesia reveals slowest earthquake eve...

A slow-motion earthquake lasting 32 years—the slowest ever recorded—eventually led to the catastrophic 1861 Sumatra earthquake, researchers at the Nanyang Technological University, Singapore (NTU Singapore) have found.

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Study finds 'ghost forests' contribute to greenhouse gas emissions

A new study from North Carolina State University finds that greenhouse gas (GHG) emissions from standing dead trees in coastal wetland forests—colloquially called "tree farts"—need to be accounted for when assessing the environmental impact of so-called "ghost forests."

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Mechanism deciphered: How organic acids are formed in the atmosphere

The acidity of the atmosphere is increasingly determined by carbon dioxide and organic acids such as formic acid. The second of these contribute to the formation of aerosol particles as a precursor of raindrops and therefore impact the growth of clouds and pH of rainwater. In previous atmospheric chemistry models of acid formation, formic acid tended to play a small role. The chemical processes behind its formation were not well understood. An international team of researchers under the aegis of Forschungszentrum Jülich has now succeeded in filling this gap and deciphering the dominant mechanism in the formation of formic acid. This makes it possible to further refine atmosphere and climate models. The results of the study have now been published in the peer-reviewed journal Nature.

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A low-cost solution to remove arsenic from drinking water

High levels of a naturally occurring chemical called arsenic have been a source of contamination of ground-based drinking water, such as well-water, for people in many countries around the world, including parts of the United States. Consuming arsenic-contaminated water is a serious public health issue, leading to severe health complications including skin, lung, bladder, kidney and liver cancers, according to the National Institute of Environmental Health Sciences.

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