Comment

Comment by Dr. Krishna Kumari Challa on November 19, 2021 at 9:16am

the results also show a clear inverse relationship between the level of antigenic diversity in a given year and epidemic levels. When Thailand experienced large epidemic outbreaks, antigenic diversity was low. But in years when epidemic levels were lower than average, the antigenic diversity was higher.

"In general, it's been thought that if you get infected with one serotype of DENV then you are immune to that serotype for the rest of your life. But there have been observations where that seems to not be strictly true."

One explanation for re-infections is that dengue viruses may be subject to natural selective forces to evade the immune system of previously infected individuals. In essence, they must change just enough to avoid immune detection in a host where another serotype has already caused an infection.

These findings suggest that the dengue viruses are moving away from the viruses that generated immunity in the population in the past. It's sort of like the flu story, dengue is evolving to escape the immunity that is in the population at any particular time. But it seems to be happening at a slower pace with dengue than influenza.

Researchers already knew that there is a complex interplay between immunity and the dengue virus. When someone is exposed to a serotype of this virus, they will typically experience a mild infection that results in partial infection. But when they are exposed again, the partial immunity can trigger an overreaction that can lead to serious outcomes. The dengue virus appears, in these cases, to not only evade the immune response, but use it to its advantage to potentially increase its rate of growth.

Ninety to 95% of the people showing up at a hospital in Bangkok with dengue are having their second infection. "And most people who live their whole lives in Bangkok are getting infected multiple times."

This enhanced infection phenomenon may also contribute to the evolution of the pathogen, selecting for viruses that are similar enough to take advantage of the Immune response.

Overall, viruses were growing more different from each other over time, but scientists also observed that they grew closer together during some periods of time, particularly early in the time series. This indicates a tradeoff between evading immunity and taking advantage of partial immunity.

This paper is suggesting that the dengue viruses are changing and we need to update how we do surveillance to better understand immunity in populations and to ultimately reduce the number of people who get sick.

Leah Katzelnick et al, Antigenic evolution of dengue viruses over 20 years, Science (2021). DOI: 10.1126/science.abk0058. www.science.org/doi/10.1126/science.abk0058

https://phys.org/news/2021-11-host-immunity-viral-evolution-dengue....

Part 3

Comment by Dr. Krishna Kumari Challa on November 19, 2021 at 9:11am

The new study used 1,944 archival blood samples from Bangkok. The samples were preserved from people known to be ill with dengue and they represent all four dengue virus strains from every year between 1994 and 2014. The team genetically sequenced more than 2,000 virus samples.

The researchers then performed tests on a smaller subset of samples that represented a time series of each strain. From this, they then characterized the antigenic relationship of the strains to each other through time. Antigenic relationships characterize how well an immune response to one virus protects against other viruses.

Researchers  found that there is a pattern like influenza, where you get different viruses every year that are driven by natural selection for viruses that evade the human immune response to the population.  This work shown that that this is also happening with dengue.

The team used a process called antigenic cartography which makes a map to visualize the relatedness of viruses.

"When two viruses are close on that map, then that means immune responses 'sees' the viruses as similar," Katzelnick says. "For example, if you are infected with one virus, then an immune response to that virus would protect you against another virus that is nearby on the map."

The team found an overall pattern of dengue virus strains evolving away from each other over the 20-year study timeframe. While the serotypes at times oscillated closer, in general they grew further apart.

Part 2

Comment by Dr. Krishna Kumari Challa on November 19, 2021 at 9:09am

Host immunity drives viral evolution of dengue

New research by a team of investigators, provides evidence that host immunity drives evolution of the dengue virus. The work, published recently in Science, retrospectively analyzes two decades of dengue virus genetic variation from Thailand, alongside population-level measures of infection and immunity.

There are four types of dengue virus, and all four have co-circulated in Thailand since the early 1960s. This provides an opportunity to study how the viruses compete against each other for human hosts.

Dengue virus types are grouped according to how their surface proteins, or antigens, interact with infection-fighting antibodies in human blood. The four types, also called serotypes, are noted as DENV1 through DENV4. Although there is genetic variation between each dengue virus type, there is also variation within each dengue virus type.

Part 1

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Comment by Dr. Krishna Kumari Challa on November 19, 2021 at 9:03am

Energizer atoms: Physicists find new way to keep atoms excited

Researchers have tricked nature by tuning a dense quantum gas of atoms to make a congested "Fermi sea," thus keeping atoms in a high-energy state, or excited, for about 10% longer than usual by delaying their normal return to the lowest-energy state. The technique might be used to improve quantum communication networks and atomic clocks.

Quantum systems such as atoms that are excited above their resting state naturally calm down, or decay, by releasing light in quantized portions called photons. This common process is evident in the glow of fireflies and emission from LEDs. The rate of decay can be engineered by modifying the environment or the internal properties of the atoms. Previous research has modified the electromagnetic environment; the new work focuses on the atoms.

The new  method relies on a rule of the quantum world known as the Pauli exclusion principle, which says identical fermions (a category of particles) can't share the same quantum states at the same time. Therefore, if enough fermions are in a crowd—creating a Fermi sea—an excited fermion might not be able to fling out a photon as usual, because it would need to then recoil. That recoil could land it in the same quantum state of motion as one of its neighbors, which is forbidden due to a mechanism called Pauli blocking.

The blocking achievement is described in the Nov. 19 issue of Science. 

Pauli blocking uses well-organized quantum motional states of a Fermi sea to block the recoil of an atom that wants to decay, thus prohibiting spontaneous decay. It is a profound quantum effect for the control of matter's properties that was previously deemed unchangeable.

Christian Sanner et al, Pauli blocking of atom-light scattering, Science (2021). DOI: 10.1126/science.abh3483. www.science.org/doi/10.1126/science.abh3483

https://phys.org/news/2021-11-energizer-atoms-physicists.html?utm_s...

Comment by Dr. Krishna Kumari Challa on November 18, 2021 at 10:22am

Seaweed-Like Device Generates Electricity Underwater

Comment by Dr. Krishna Kumari Challa on November 18, 2021 at 10:18am

Using nematodes to sniff out cancer

 A screening test using tiny worms to detect early signs of pancreatic cancer in urine has been developed by a  biotech firm, which hopes it could help boost routine screening.

Scientists have long known that the bodily fluids of cancer patients smell different to those of healthy people, with dogs trained to detect the disease in breath or urine samples.

But Hirotsu Bio Science has genetically modified a type of worm called "C. elegans" -- around one millimetre long, with an acute sense of smell -- to react to the urine of people with pancreatic cancer, which is notoriously difficult to detect early.

The  firm has already used the worms to detect cancer in screening tests, though without specifying which type.

The new test is not meant to diagnose pancreatic cancer, but could help boost routine screening as urine samples can be collected at home without the need for a hospital visit.

 If the worms raise the alarm, the patient would then be referred to a doctor for further testing. In separate tests conducted by the firm, the worms correctly identified all 22 urine samples from pancreatic cancer patients, including people with early stages of the disease.

https://journals.plos.org/plosone/article?id=10.1371/journal.pone.0...

https://researchnews.cc/news/10038/What-a-worm--Japan-firm-uses-nem...

Comment by Dr. Krishna Kumari Challa on November 18, 2021 at 9:03am

Understanding how proteins are broken down in cells using advanced microscopes

How do organisms break down proteins when they are finished doing their job?

Protein degradation is a carefully orchestrated process. Proteins are marked for disposal with a molecular label called ubiquitin, and then fed into proteasomes, a kind of cellular paper shredder that chops up the proteins into small pieces. This process of ubiquitination, or labeling proteins with ubiquitin, is involved in a wide range of cellular processes, including cell division, DNA repair, and immune responses.

In a new study published in Nature on November 17, 2021, researchers used advanced electron microscopes to delve deeper into the process of protein degradation. They described the structure of a key enzyme that helps mediate ubiquitination in yeast, part of a cellular process called the N-degron pathway that may be responsible for determining the rate of degradation for up to 80% of equivalent proteins in humans. Malfunctions in this pathway can lead to accumulation of damaged or misfolded proteins, which underlies the aging process, neurodegeneration, and some rare autosomal recessive disorders, so understanding it better provides an opportunity to develop treatments.

Researchers were able to describe the structure of several intermediate enzyme complexes involved in the pathway, which will help researchers looking for ways to target proteins with drugs or intervene in a malfunctioning protein degradation process.

 Minglei Zhao, Structural insights into Ubr1-mediated N-degron polyubiquitination, Nature (2021). DOI: 10.1038/s41586-021-04097-8. www.nature.com/articles/s41586-021-04097-8

https://phys.org/news/2021-11-advanced-microscopes-scientists-cells...

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Comment by Dr. Krishna Kumari Challa on November 18, 2021 at 8:39am

Researchers find the finger snap to have the highest acceleration the human body produces

Snapping of fingers: Using an intermediate amount of friction, not too high and not too low, a snap of the finger produces the highest rotational accelerations observed in humans, even faster than the arm of a professional baseball pitcher. The results were published Nov. 17 in the Journal of the Royal Society Interface.

 In earlier work researc

hers had developed a general framework for explaining the surprisingly powerful and ultrafast motions observed in living organisms. The framework seemed to naturally apply to the snap. It posits that organisms depend on the use of a spring and latching mechanism to store up energy, which they can then quickly release.

Using high-speed imaging, automated image processing, and dynamic force sensors, the researchers analyzed a variety of finger snaps. They explored the role of friction by covering fingers with different materials, including metallic thimbles to simulate the effects of trying to snap while wearing a metallic gauntlet, much like Thanos.

For an ordinary snap with bare fingers, the researchers measured maximal rotational velocities of 7,800 degrees per second and rotational accelerations of 1.6 million degrees per second squared. The rotational velocity is less than that measured for the fastest rotational motions observed in humans, which come from the arms of professional baseball players during the act of pitching. However, the snap acceleration is the fastest human angular acceleration yet measured, almost three times faster than the rotational acceleration of a professional baseball pitcher's arm.

The finger snap occurs in only seven milliseconds, more than twenty times faster than the blink of an eye, which takes more than 150 milliseconds.

When the fingertips of the subjects were covered with metal thimbles, their maximal rotational velocities decreased dramatically, confirming the researchers' imaginations.

Reducing both the compressibility and friction of the skin by using things like metal armours make it a lot harder to build up enough force in your fingers to actually snap.

Surprisingly, increasing the friction of the fingertips with rubber coverings also reduce speed and acceleration. The researchers concluded that a Goldilocks zone of friction was necessary—too little friction and not enough energy was stored to power the snap, and too much friction led to energy dissipation as the fingers took longer to slide past each other, wasting the stored energy into heat.

The ultrafast snap of a finger is mediated by skin friction, Journal of the Royal Society Interface (2021). DOI: 10.1098/rsif.2021.0672. rsif.royalsocietypublishing.or … .1098/rsif.2021.0672

https://phys.org/news/2021-11-art-finger-snap-highest-human.html?ut...

Comment by Dr. Krishna Kumari Challa on November 17, 2021 at 10:29am

The results : The most striking result is the very high estimated probability of winning when batting second in Dubai (where Australia triumphed in the tournament’s final). Even when the batting-second team was ranked lower than its opponent, there still was a high estimated probability of victory.

The analysis revealed some evidence that it was beneficial to bat second in this world cup, but this is likely to depend greatly on the conditions. If we assume a match is played on a randomly selected pitch from the four venues used, and there is a 50% chance the higher-ranked team bats second, my model estimates the probability of winning when batting second is around 0.6, with a 95% confidence interval of 0.48 to 0.71.

So there is a likely benefit to batting second, but it’s far from a foregone conclusion.

https://theconversation.com/does-batting-second-in-t20-world-cup-cr...

Part 4

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Comment by Dr. Krishna Kumari Challa on November 17, 2021 at 10:06am

 analysis found that the timing of the match did not statistically influence the winning probability of the team batting second. In other words, the advantage of batting first or second did not depend on whether the match was staged during the afternoon or the evening.

That leaves two variables that might conceivably influence the situation: the venue hosting the match, and whether the team batting second has a higher or lower ranking than its opponent. That gives eight possible combinations (four venues times two possibilities for batting order) for which the statistical model can generate results.

Because there is just a handful of matches in each category, we can strengthen our statistical analysis using a concept called the “95% confidence interval”. Rather than generating only a single probability estimate, we can also calculate an upper and lower limit to our estimate, between which we can be 95% confident that the true probability is found.

Part 3

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