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Comment by Dr. Krishna Kumari Challa on November 11, 2021 at 8:24am

Humans are guilty of breaking an oceanic law of nature: study

A new international study has examined the distribution of biomass across all life in the oceans, from bacteria to whales. Their quantification of human impact reveals a fundamental alteration to one of life's largest scale patterns.

Scientists have used advances in ocean observation and large meta-analyses to show that human impacts have already had major consequences for the larger oceanic species, and have dramatically changed one of life's largest scale patterns—a pattern encompassing the entire ocean's biodiversity, from bacteria to whales.

Early samples of marine plankton biomass from 50 years ago led researchers to hypothesize that roughly equal amounts of biomass occur at all sizes. For example, although bacteria are 23 orders of magnitude smaller than a blue whale, they are also 23 orders of magnitude more abundant. This size-spectrum hypothesis has since remained unchallenged, even though it was never verified globally from bacteria to whales. The authors of the study, published in the journal Science Advances, sought to test this hypothesis on a global scale for the first time. They used historical reconstructions and marine ecosystem models to estimate biomass before industrial scale fishing got underway (pre-1850) and compared this data to the present-day.

One of the biggest challenges to comparing organisms spanning bacteria to whales is the enormous differences in scale.

The ratio of their masses is equivalent to that between a human being and the entire Earth. Researchers estimated organisms at the small end of the scale from more than 200,000 water samples collected globally, but larger marine life required completely different methods.

Their approach focused on 12 major groups of aquatic life over roughly 33,000 grid points of the ocean. Evaluating the pre-industrial ocean conditions (pre-1850) largely confirmed the original hypothesis: There is a remarkably constant biomass across size classes.

Researchers were amazed to see that each order of magnitude size class contains approximately 1 gigaton of biomass globally.

While bacteria are over-represented in the cold, dark regions of the ocean, the largest whales are relatively rare, thus highlighting exceptions from the original hypothesis.

In contrast with an even biomass spectrum in the pre-1850 ocean, an investigation of the spectrum at present revealed human impacts on ocean biomass through a new lens. While fishing and whaling only account for less than 3 percent of human food consumption, their effect on the biomass spectrum is devastating: large fish and marine mammals such as dolphins have experienced a biomass loss of 2 Gt (60% reduction), with the largest whales suffering an unsettling almost 90% decimation. The authors estimate that these losses already outpace potentialbiomass losses even under extreme climate change scenarios.

Humans have impacted the ocean in a more dramatic fashion than merely capturing fish. It seems that we have broken the size spectrum—one of the largest power law distributions known in nature.  These results provide a new quantitative perspective on the extent to which anthropogenic activities have altered life at the global scale. 

Ian A. Hatton et al, The global ocean size spectrum from bacteria to whales, Science Advances (2021). DOI: 10.1126/sciadv.abh3732

https://phys.org/news/2021-11-humans-guilty-oceanic-law-nature.html

Comment by Dr. Krishna Kumari Challa on November 10, 2021 at 11:54am

White-tailed deer found to be huge reservoir of coronavirus infection

New research from the US has shown that white-tailed deer are being infected with SARS-CoV-2, the virus that causes COVID-19 in humans. Antibodies were found in 40% of deer that were tested from January to March 2021 across Michigan, Pennsylvania, Illinois and New York state. A second unpublished study has detected the virus in 80% of deer sampled in Iowa between November 2020 and January 2021.

Such high levels of infection led the researchers to conclude that deer are actively transmitting the virus to one another. The scientists also identified different SARS-CoV-2 variants, suggesting there have been many human-to-deer infections.

The large numbers of white-tailed deer in North America and the fact that they often live close to people provide several opportunities for the disease to move between the two species. This can include wildlife management operations, field research, recreation, tourism and hunting. In fact, hunters are likely to be one of the most obvious sources of potential reinfection as they regularly handle dead animals. It has also been suggested that water sources contaminated with SARS-CoV-2 might provide a pathway for transmission, although this has yet to be proved.

Human-to-deer and deer-to-deer transmission are believed to be driving the rapid spread of the disease within white-tailed deer populations across the US. This is particularly apparent during the early months of 2021 when COVID infections were spiking in the human population. Previous studies have shown that SARS-CoV-2 can be passed from humans to domestic and captive animals including cats, dogs, zoo animals and, most notably, farmed mink. But, until now, the disease had not been shown to spread in wildlife species.

There is the possibility that viral mutation in a reservoir host, such as white-tailed deer, could lead to new variants of the disease. These variants may lead to greater infection rates, increased virulence (severity of symptoms) and prove more effective at evading the human immune system. Likewise, any reinfection from wildlife reservoirs could also complicate our long-term efforts to fight and suppress the disease.

https://www.pnas.org/content/118/47/e2114828118

https://www.biorxiv.org/content/10.1101/2021.10.31.466677v1

https://theconversation.com/white-tailed-deer-found-to-be-huge-rese...

Comment by Dr. Krishna Kumari Challa on November 10, 2021 at 11:42am

Modified silk cloth keeps skin cooler than cotton

A team of researchers has developed a modified textile that can keep skin cooler than materials made of cotton. In their paper published in the journal Nature Nanotechnology, the group describes their approach to developing garments that are cooler when worn in outdoor conditions.

The researchers noted that silk does a good job of reflecting sunlight in the mid-infrared range, which suggests it could be suitable as a cooling garment material. But because it is made by spiders, it contains a protein component that tends to absorb ultraviolet radiation, making the material and its wearer grow hotter under direct sunlight.

To make the silk material UV reflective, the researchers dipped a standard piece of silk fabric into a liquid solution containing highly refractive inorganic oxide nanoparticles. These adhered to the silk fabric, allowing it to become evenly saturated throughout the material. They allowed the fabric to dry and then tested it to see if the addition of the nanoparticles made the material more UV reflective. They found that under peak sunlight conditions, the temperature under the material was approximately 3.5 degrees Celsius cooler than the ambient air temperature. Next, they placed the material on a patch of simulated skin and found the skin temperature was approximately 8 degrees Celsius cooler than the same type of simulated skin without the material covering. They also found that it kept the artificial skin approximately 12.5 degrees Celsius cooler than standard cotton material. Further testing showed that the material was able to reflect approximately 95% of sunlight, preventing it from passing through to the skin underneath.

Bin Zhu et al, Subambient daytime radiative cooling textile based on nanoprocessed silk, Nature Nanotechnology (2021). DOI: 10.1038/s41565-021-00987-0

https://phys.org/news/2021-11-silk-skin-cooler-cotton.html?utm_sour...

Comment by Dr. Krishna Kumari Challa on November 10, 2021 at 11:28am

How are epilepsy and autism linked?

Epilepsy and autism spectrum disorders, or ASD, show a remarkable degree of comorbidity and may share pathological mechanisms. Questions that have bogged down scientists about these disorders include: Does autism lead to an increase in epilepsy? Or does epilepsy alter the brain circuit, which then leads to autism?

One hypothesis is that during brain development, inhibitory neurons,  which regulate brain rhythms, develop in an abnormal manner. If this is true, then how the brain circuit gets set up is abnormal, which may lead to both autism and epilepsy. 

unlike excitatory neurons that lead to a forward propagation of information, inhibitory neurons work like a brake by suppressing and sculpting the activity of downstream neurons.

The researchers generated mice with a global mutation in all cells that prevented the inhibitory neurons from migrating to their normal location in mature brain circuits. Not surprisingly, they found a reduction in inhibitory currents in the hippocampus, a region of the brain known for memory function. Notably, the mutant mice showed behavioral traits associated with ASD and were more prone to seizures.

Results of the study suggest that a common underlying defect in circuit formation could contribute to both ASD and epilepsy.

Carol Eisenberg et al, Reduced hippocampal inhibition and enhanced autism-epilepsy comorbidity in mice lacking neuropilin 2, Translational Psychiatry (2021). DOI: 10.1038/s41398-021-01655-6

https://medicalxpress.com/news/2021-11-epilepsy-autism-linked.html?...

Comment by Dr. Krishna Kumari Challa on November 10, 2021 at 8:11am

We don’t ‘believe in’ Newton’s laws. We trust them and accepted them because there is genuine evidence that they work.

Newton's laws of motion are three laws of classical mechanics that describe the relationship between the motion of an object and the forces acting on it. These laws can be paraphrased as follows (1):

Law 1. A body continues in its state of rest, or in uniform motion in a straight line, unless acted upon by a force.

Law 2. A body acted upon by a force moves in such a manner that the time rate of change of momentum equals the force.

Law 3. If two bodies exert forces on each other, these forces are equal in magnitude and opposite in direction.

Newton's laws were verified by experiment and observation for over 200 years, and they are excellent approximations at the scales and speeds of everyday life. 

1. https://en.wikipedia.org/wiki/Newton%27s_laws_of_motion

Comment by Dr. Krishna Kumari Challa on November 9, 2021 at 8:12am

Why teapots always drip

The "teapot effect" has been threatening spotless white tablecloths for ages: if a liquid is poured out of a teapot too slowly, then the flow of liquid sometimes does not detach itself from the teapot, finding its way into the cup, but dribbles down at the outside of the teapot.

This phenomenon has been studied scientifically for decades—now a research team  has succeeded in describing the "teapot effect" completely and in detail with an elaborate theoretical analysis and numerous experiments: An interplay of different forces keeps a tiny amount of liquid directly at the edge, and this is sufficient to redirect the flow of liquid under certain conditions.

The "teapot effect" was first described by Markus Reiner in 1956.

So rheology is the science of flow behavior. Again and again, scientists have tried to explain this effect precisely. Although this is a very common and seemingly simple effect, it is remarkably difficult to explain it exactly within the framework of fluid mechanics. 

The sharp edge on the underside of the teapot beak plays the most important role: a drop forms, the area directly below the edge always remains wet. The size of this drop depends on the speed at which the liquid flows out of the teapot. If the speed is lower than a critical threshold, this drop can direct the entire flow around the edge and dribbles down on the outside wall of the teapot.

Researchers  have now succeeded for the first time in providing a complete theoretical explanation of why this drop forms and why the underside of the edge always remains wetted. 

 The mathematics behind it is complicated—it is an interplay of inertia, viscous and capillary forces. The inertial force ensures that the fluid tends to maintain its original direction, while the capillary forces slow the fluid down right at the beak. The interaction of these forces is the basis of the teapot effect. However, the capillary forces ensure that the effect only starts at a very specific contact angle between the wall and the liquid surface. The smaller this angle is or the more hydrophilic (i.e. wettable) the material of the teapot is, the more the detachment of the liquid from the teapot is slowed down.

Interestingly, the strength of gravity in relation to the other forces that occur does not play a decisive role. Gravity merely determines the direction in which the jet is directed, but its strength is not decisive for the teapot effect. The teapot effect would therefore also be observed when drinking tea on a moon base, but not on a space station with no gravity at all.

B. Scheichl et al, Developed liquid film passing a smoothed and wedge-shaped trailing edge: small-scale analysis and the 'teapot effect' at large Reynolds numbers, Journal of Fluid Mechanics (2021). DOI: 10.1017/jfm.2021.612

https://phys.org/news/2021-11-teapots.html?utm_source=nwletter&...

Comment by Dr. Krishna Kumari Challa on November 8, 2021 at 11:43am

Comment by Dr. Krishna Kumari Challa on November 8, 2021 at 8:17am

Why Arthritis Keeps Flaring Up in The Same Joints

According to new research conducted on mice, this could be because our immune system keeps a record of these past afflictions, creating a personalized disease pattern in each individual. Understanding more about how and why this happens could open up new opportunities for treating the disorder.

This latest study zooms in on the T cells in mice's bodies, white blood cells that are key to the immune system. In particular, the T cells in the synovium – the tissue lining the inside of the capsule around each joint – appear to hold a memory of previous RA problems.

Overwhelmingly, flares occur in a previously involved joint. The study shows that  these T cells anchor themselves in the joints and stick around indefinitely after the flare is over, waiting for another trigger. If you delete these cells, arthritis flares stop.

This was demonstrated through two mouse models using chemical triggers to cause joint inflammation and one mouse model using a genetic trigger to generate the same effect: The researchers removed a protein that blocked the pro-inflammatory cytokine IL-1.

These triggers caused T cells to rally other cells to the immunity cause, leading to arthritis flare-ups in specific joints in the mice. When these T cells were taken out, additional inflammation was prevented. These T cells don't move between joints and take up "long-term residency" where they are, the researchers say, ready to be reactivated again.

The approach taken here was actually inspired by skin studies. T cells with a form of memory are known to reside in the skin, leading to repeating patterns in skin problems such as psoriasis. It also happens with reactions to nickel in jewelry or wristwatches.

The research team thinks that other types of autoimmune arthritis could work in the same way, which could lead to better treatments and approaches to these issues. The next step is to confirm that the same process happens in humans and find out ways to target it.

https://www.cell.com/cell-reports/fulltext/S2211-1247(21)01372-3

https://www.sciencealert.com/immune-system-memory-might-explain-why...

Comment by Dr. Krishna Kumari Challa on November 8, 2021 at 6:54am

Dr. Kamal Ranadive’s 104th BirthdayToday’s (google's) Doodle celebrates Indian cell biologist Dr. Kamal Ranadive, who is best known for her groundbreaking cancer research and devotion to creating a more equitable society through science and education.

Kamal Ranadive was an Indian biomedical researcher who is known for her research in cancer about the links between cancers and viruses. She was a founder member of the Indian Women Scientists' Association.

Comment by Dr. Krishna Kumari Challa on November 7, 2021 at 12:08pm

How bacteria can clean up oil spills too 

Bacteria are often painted as our adversaries, but when it comes to oil spills, toxic chemicals, and radioactive waste, they could be what save us from ourselves.

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