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Comment by Dr. Krishna Kumari Challa on July 29, 2021 at 12:18pm

Motivation depends on how the brain processes fatigue

How do we decide whether or not an activity which requires work is 'worth the effort'? Researchers  have shown that the willingness to work is not static, and depends upon the fluctuating rhythms of fatigue.

Fatigue—the feeling of exhaustion from doing effortful tasks—is something we all experience daily. It makes us lose motivation and want to take a break. Although scientists understand the mechanisms the brain uses to decide whether a given task is worth the effort, the influence of fatigue on this process is not yet well understood.

The research team conducted a study to investigate the impact of fatigue on a person's decision to exert effort. They found that people were less likely to work and exert effort—even for a reward—if they were fatigued. The results are published in Nature Communications.

Intriguingly, the researchers found that there were two different types of fatigue that were detected in distinct parts of the brain. In the first, fatigue is experienced as a short-term feeling, which can be overcome after a short rest. Over time, however, a second, longer term feeling builds up, stops people from wanting to work, and doesn't go away with short rests.

Tanja Müller et al, Neural and computational mechanisms of momentary fatigue and persistence in effort-based choice, Nature Communications (2021). DOI: 10.1038/s41467-021-24927-7

Comment by Dr. Krishna Kumari Challa on July 29, 2021 at 12:08pm

Earth's 'vital signs' worsening as humanity's impact deepens

The global economy's business-as-usual approach to climate change has seen Earth's "vital signs" deteriorate to record levels, an influential group of scientists said recently, warning that several climate tipping points were now imminent.

The researchers, part of a group of more than 14,000 scientists who have signed on to an initiative declaring a worldwide climate  emergency, said that governments had consistently failed to address the root cause of climate change: "the overexploitation of the Earth".

Of 31 "vital signs"—key metrics of planetary health that include greenhouse gas emissions, glacier thickness, sea-ice extent and deforestation—they found that 18 hit record highs or lows.

For example, despite a dip in pollution linked to the pandemic, levels of atmospheric CO2 and methane hit all-time highs in 2021.

Greenland and Antarctica both recently showed all-time low levels of ice mass, and glaciers are melting 31 percent faster than they did just 15 years ago, the authors said.

Both ocean heat and global sea levels set new records since 2019, and the annual loss rate of the Brazilian Amazon reached a 12-year high in 2020.

Echoing previous research, they said that forest degradation linked to fire, drought and logging was causing parts of the Brazilian Amazon to now act as a source of carbon, rather than absorb the gas from the atmosphere.

Livestock such as cows and sheep are now at record levels, numbering more than four billion and with a mass exceeding that of all humans and wild land mammals combined, they said.

We need to respond to the evidence that we are hitting climate tipping points with equally urgent action to decarbonise the global economy and start restoring instead of destroying nature, they stressed.

The researchers said there was "mounting evidence that we are nearing or have already crossed" a number of climate tipping points.

https://academic.oup.com/bioscience/advance-article/doi/10.1093/bio...

https://phys.org/news/2021-07-earth-vital-worsening-humanity-impact...

Comment by Dr. Krishna Kumari Challa on July 29, 2021 at 10:51am

The Hidden Beauty of Rainbows

Comment by Dr. Krishna Kumari Challa on July 28, 2021 at 10:35am

Physicists Have Figured Out How We Could Make Antimatter Out of Light

A new study by scientists has demonstrated how researchers may be able to create an accelerating jet of antimatter from light.

A team of physicists has shown that high-intensity lasers can be used to generate colliding gamma photons – the most energetic wavelengths of light – to produce electron-positron pairs. This, they say, could help us understand the environments around some of the Universe's most extreme objects: neutron stars.

The process of creating a matter-antimatter pair of particles – an electron and a positron – from photons is called the Breit-Wheeler process, and it's extremely difficult to achieve experimentally.

The probability of it taking place when two photons collide is very small. You need very high-energy photons, or gamma rays, and a lot of them, in order to maximize the chances of observation.

We don't yet have the capability to build a gamma-ray laser, so the photon-photon Breit-Wheeler process currently remains experimentally unachieved. But a team of physicists led by Yutong He of the University of California, San Diego (UC San Diego) has proposed a new workaround that, according to their simulations, could actually work.

It consists of a plastic block, carved with a pattern of criss-crossing channels on the micrometer scale. Two powerful lasers, one on either side of the block, fire strong pulses at this target.

"When the laser pulses penetrate the sample, each of them accelerates a cloud of extremely fast electrons. 

These two electron clouds then race toward each other with full force, interacting with the laser propagating in the opposite direction."

The resulting collision is so energetic that it produces a cloud of gamma photons. These gamma photons should collide with each other to produce electron-positron pairs,  in accordance with Einstein's theory of general relativity.

Even more excitingly, this process should generate powerful magnetic fields that collimate the positrons (rather than the electrons) into strongly accelerated, jet-shaped beams. In a distance of just 50 micrometers, the researchers found, the acceleration should increase the energy of the particles to one gigaelectronvolt.

Using a complex computer simulation, the researchers tested their model, and found that it should work, even when using less powerful lasers than previous proposals.

Not only would the collimation and acceleration of the positron beam improve the detection rate of the particles, but it bears a strong similarity to the powerful collimated particle jets beamed out by strongly magnetic, rapidly rotating neutron stars known as pulsars.

Scientists believe that processes that take place close to these stars could result in clouds of gamma radiation, similar to their proposed experiment.

https://www.nature.com/articles/s42005-021-00636-x

https://www.sciencealert.com/physicists-have-figured-out-how-we-cou...

Comment by Dr. Krishna Kumari Challa on July 28, 2021 at 9:50am

Fingertip-powered wearable

Comment by Dr. Krishna Kumari Challa on July 28, 2021 at 9:47am

'Good cholesterol' may protect liver

 The body's so-called good cholesterol may be even better than we realize. New research from Washington University School of Medicine in St. Louis suggests that one type of high-density lipoprotein (HDL) has a previously unknown role in protecting the liver from injury. This HDL protects the liver by blocking inflammatory signals produced by common gut bacteria. The study was published July 23 in the journal Science. HDL is mostly known for mopping up cholesterol in the body and delivering it to the liver for disposal. But in the new study, the researchers identified a special type of HDL called HDL3 that, when produced by the intestine, blocks gut bacterial signals that cause liver inflammation. If not blocked, these bacterial signals travel from the intestine to the liver, where they activate immune cells that trigger an inflammatory state, which leads to liver damage. Even though HDL has been considered good cholesterol,’ drugs that increase overall HDL levels have fallen out of favor in recent years because of clinical trials that showed no benefit in cardiovascular disease.  study suggests that raising levels of this specific type of HDL, and specifically raising it in the intestine, may hold promise for protecting against liver disease, which, like heart disease, also is a major chronic health problem.

Any sort of intestinal damage can impact how a group of microbes called Gram-negative bacteria can affect the body. Such microbes produce an inflammatory molecule called lipopolysaccharide that can travel to the liver via the portal vein. The portal vein is the major vessel that supplies blood to the liver, and it carries most nutrients to the liver after food is absorbed in the intestine. Substances from gut microbes may travel along with nutrients from food to activate immune cells that trigger inflammation. In this way, elements of the gut microbiome may drive liver disease, including fatty liver disease and liver fibrosis, in which the liver develops scar tissue.

https://researchnews.cc/news/8017/-Good-cholesterol--may-protect-li...

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Comment by Dr. Krishna Kumari Challa on July 28, 2021 at 9:39am

When our defences turn on us

When the body becomes the target of its own defensive arsenal, medicine must step in. This Nature Outlook explores why autoimmune disease is around three times more common in women than in men, the genetic variants that increase the risk of autoimmunity and how the microbes in our gut might sometimes be to blame. It also reveals how the possible links between long COVID and the immune system might finally prove that viruses can spark autoimmune disease.

Nature | Full collection

Comment by Dr. Krishna Kumari Challa on July 27, 2021 at 1:04pm

The Universe has an average colour – and it’s called cosmic latte

In a 2002 study, astronomers found that the light coming from galaxies (and the stars within them) – alongside all the visible clouds of gas and dust in the Universe – when averaged, would produce an ivory colour very close to white. They named this colour ‘cosmic latte’.

The ‘beigeness’ of the Universe is because there are slightly more regions that produce red, yellow and green light than those that produce blue. Averaged over the entire sky, however, this beige colour is diluted and appears almost, but not entirely, black.

https://www.sciencefocus.com/space/universe-average-colour-cosmic-l...

Comment by Dr. Krishna Kumari Challa on July 27, 2021 at 12:51pm

Acoustic Manipulation off a Reflective Surface

https://www.sciencealert.com/scientists-have-developed-a-new-way-to...

Comment by Dr. Krishna Kumari Challa on July 27, 2021 at 12:39pm

A Lagoon in Argentina Turned Bright Pink, But This Time The Reason Is Unnatural

A lagoon in Argentina's southern Patagonia region has turned bright pink in a striking, but frightful phenomenon experts and activists blame on pollution by a chemical used to preserve prawns for export.

The color is caused by sodium sulfite, an anti-bacterial product used in fish factories, whose waste is blamed for contaminating the Chubut river that feeds the Corfo lagoon and other water sources in the region, according to activists.

Residents have long complained of foul smells and other environmental issues around the river and lagoon.

Environmental engineer and virologist Federico Restrepo told AFP the coloration was due to sodium sulfite in fish waste, which by law, should be treated before being dumped.

https://www.sciencealert.com/prawn-chemical-turns-argentina-lake-br...

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