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Comment by Dr. Krishna Kumari Challa on November 30, 2021 at 9:10am

Salt grain size camera!

Micro-sized cameras have great potential to spot problems in the human body and enable sensing for super-small robots, but past approaches captured fuzzy, distorted images with limited fields of view.

But now, researchers  have overcome these obstacles with an ultracompact camera the size of a coarse grain of salt. The new system can produce crisp, full colour images on par with a conventional compound camera lens 500,000 times larger in volume, the researchers reported in a paper published Nov. 29 in Nature Communications.

Enabled by a joint design of the camera's hardware and computational processing, the system could enable minimally invasive endoscopy with medical robots to diagnose and treat diseases, and improve imaging for other robots with size and weight constraints. Arrays of thousands of such cameras could be used for full-scene sensing, turning surfaces into cameras.

While a traditional camera uses a series of curved glass or plastic lenses to bend light rays into focus, the new optical system relies on a technology called a metasurface, which can be produced much like a computer chip. Just half a millimeter wide, the metasurface is studded with 1.6 million cylindrical posts, each roughly the size of the human immunodeficiency virus (HIV).

Each post has a unique geometry, and functions like an optical antenna. Varying the design of each post is necessary to correctly shape the entire optical wavefront. With the help of machine learning-based algorithms, the posts' interactions with light combine to produce the highest-quality images and widest field of view for a full-color metasurface camera developed to date.

A key innovation in the camera's creation was the integrated design of the optical surface and the signal processing algorithms that produce the image. This boosted the camera's performance in natural light conditions.

 Ethan Tseng et al, Neural nano-optics for high-quality thin lens imaging, Nature Communications (2021). DOI: 10.1038/s41467-021-26443-0

https://phys.org/news/2021-11-camera-size-salt-grain.html?utm_sourc...

Comment by Dr. Krishna Kumari Challa on November 30, 2021 at 9:05am

Study suggests Sun is likely an unaccounted source of the Earth's water

Researchers have helped unravel the enduring mystery of the origins of the Earth's water, finding the Sun to be a surprising likely source. They found the solar wind, comprised of charged particles from the Sun largely made of hydrogen ions, created water on the surface of dust grains carried on asteroids that smashed into the Earth during the early days of the Solar System.

 Earth 's very water-rich compared to other rocky planets in the Solar System, with oceans covering more than 70 percent of its surface, and scientists had long puzzled over the exact source of it all.

An existing theory is that water was carried to Earth in the final stages of its formation on C-type asteroids, however previous testing of the isotopic 'fingerprint' of these asteroids found they, on average, didn't match with the water found on Earth meaning there was at least one other unaccounted for source.

New work  suggests the solar wind created water on the surface of tiny dust grains and this isotopically lighter water likely provided the remainder of the Earth's water.

This new solar wind theory is based on meticulous atom-by-atom analysis of miniscule fragments of an S-type near-Earth asteroid known as Itokawa, samples of which were collected by the Japanese space probe Hayabusa and returned to Earth in 2010. A world-class atom probe tomography system allowed the researchers to take an incredibly detailed look inside the first 50 nanometres or so of the surface of Itokawa dust grains, which they found contained enough water that, if scaled up, would amount to about 20 liters for every cubic meter of rock.

Luke Daly, Solar wind contributions to Earth's oceans, Nature Astronomy (2021). DOI: 10.1038/s41550-021-01487-w. www.nature.com/articles/s41550-021-01487-w

Researchers discover how water is regenerated on asteroids

https://phys.org/news/2021-11-sun-unaccounted-source-earth.html?utm...

Comment by Dr. Krishna Kumari Challa on November 28, 2021 at 11:09am

Water disinfection byproduct disrupts reproductive hormones, damages pituitary in female mice

 Chemical disinfection makes water from both natural sources and wastewater streams drinkable; however, the process also creates byproducts, not all of which are understood or regulated. A new study from University of Illinois Urbana-Champaign researchers has found that one byproduct disrupts hormones in the brain that regulate the female reproductive cycle in mice and also damages cells in the pituitary gland.

Iodoacetic acid, or IAA, is created when an oxidizing disinfectant such as chlorine reacts with the iodide naturally present in water, said study leader Lori Raetzman, a professor of molecular and integrative physiology. The new study’s findings of IAA’s effects on reproductive regulation in the brain complement previous work by study co-author Jodi Flaws, a professor of comparative biosciences, which found that IAA also disrupts function in and causes damage to ovary cells, indicating that the chemical could impact the entire reproductive system.

We know we need to disinfect water, but the water that’s coming out of our taps isn’t pure – regulators only screen for the things they know about. Water regulatory bodies have not been looking for IAA. This study is contributing to the growing body of evidence that suggests that IAA may impact reproduction, so it might be reasonable to have screening for this too, and to establish a safe level for it.

In the new study, published in the journal Toxological Sciences, the researchers gave mice drinking water containing IAA at levels comparable to possible human exposure, as well as a control group of mice that were given water with no IAA present, for 35-40 days. Then they measured the production of reproduction-regulating factors in two key parts of the neuroendocrine system – the hypothalamus and the pituitary.

“Mice are often used as models for the human reproductive system because they have estrous cycles that are similar to human menstrual cycles. The hypothalamus and the pituitary are the master regulators of the endocrine system. It’s a good foundation to say that a human exposed to a certain amount of IAA could potentially have similar effects.

The researchers found that, even at low levels, IAA disrupted production of a key reproduction-regulating factor in the hypothalamus. At higher levels, IAA reduced pituitary production of follicle stimulating hormone, a key hormone for promoting egg maturation in the ovaries leading up to ovulation. The hormone also is linked to estrogen production.

n addition, the researchers saw toxic effects, including DNA damage, in the pituitaries of the mice that consumed IAA. Because of this finding and the earlier findings from the Flaws lab regarding ovarian cell damage, the researchers are now investigating whether and how exposing pregnant mice to IAA in drinking water affects their pups.

https://pubmed.ncbi.nlm.nih.gov/34453833/

DOI: 10.1093/toxsci/kfab106

https://researchnews.cc/news/10224/Water-disinfection-byproduct-dis...

Comment by Dr. Krishna Kumari Challa on November 27, 2021 at 12:10pm

Supercomputer Simulations Test Star-destroying Black Holes

Comment by Dr. Krishna Kumari Challa on November 27, 2021 at 12:05pm

Warm weather or bright lights can influence tree greening

How both global warming and bright city lights can impact phenology in trees (when they begin to grow leaves in the spring?

 In her paper published in the journal Science, Meng, the Science & SciLifeLab Prize  for young scientist's award winner, outlines her study of satellite data showing green areas in cities along with artificial light sources and also trees growing in the Alps.

Prior research has shown that higher temperatures in cities can impact vegetation growth. In this new effort, Meng wondered what city warming, combined with global warming might be doing to the times that trees "green up" in the spring each year. To find out, she obtained and analyzed satellite data that showed when trees begin producing leaves in the spring each year for 85 U.S. cities over the years 2001 to 2014.

She found that tree green-up happens on average 6 days earlier in urban areas compared to rural areas. She also found that trees in the city are responding to climate change faster than trees in rural areas.

Meng also wondered about the impact of bright lights on trees and whether they might make trees start growing their leaves earlier in the spring each year. She studied trees growing in the Alps in Europe—noting that it is a place with a rather uniform temperature distribution but also has changing lengths of daylight across latitudes. She found evidence of a reduction in an early green-up likely due to global warming. She then studied data from NASA's Black Marble satellite, which measures artificial light in cities and also phenology data from the USA National Phenology Network. This allowed her to compare conditions in cities both with and without artificial light in the U.S., and she found that artificial light pushed spring green-up by nine days in the most extreme cases.

Meng concludes by suggesting that artificial light, by supplementing day length, leads to additions of earlier spring greening in cities, adding to the impact of earlier greening due to global warming. 

Lin Meng, Green with phenology, Science (2021). DOI: 10.1126/science.abm8136

https://phys.org/news/2021-11-weather-bright-tree-greening.html?utm...

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Comment by Dr. Krishna Kumari Challa on November 27, 2021 at 11:58am

The experiment by the team involved creating a beam of deuterium and helium molecules in a chamber cooled to –272°C. They then used pairs of polarized laser bursts to push deuterium molecules into a certain vibrational and rotational state with different orientations—at right angles to one another. These served as the slits for the experiment. The team also forced other deuterium molecules into a state where they were suppositions of both of the orientations of the slits. As helium atoms scattered off the superposed molecules (along different paths that interfered with one another), the deuterium could in a sense "feel" them both at the same time. And as the helium atoms collided with the molecules, the deuterium atoms were released back to their original state at which point, they were ionized and studied by the research team.

The researchers suggest that in addition to conducting the double-slit experiment in a new way, their work also lays the groundwork for studying quantum behavior in a new way—by preparing new types of matter. They conclude by suggesting that their techniques could also be adapted for use in studying decoherence.

Haowen Zhou et al, Quantum mechanical double slit for molecular scattering, Science (2021). DOI: 10.1126/science.abl4143

https://phys.org/news/2021-11-molecules-atoms-double-slit.html?utm_...

Part 2

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Comment by Dr. Krishna Kumari Challa on November 27, 2021 at 11:57am

Using molecules and atoms to conduct the double-slit experiment

A team of researchers  has developed a way to conduct the famous double-slit experiment at the molecular level. In their paper published in the journal Science, the group describes their technique and suggest that it could be used to assist with other molecular experiments.

In 1801, Thomas Young conducted what has come to be known as the double-slit experiment. At the time, he used it as a means to prove that light behaves as a wave. Since that time, light has been found to also behave as a particle of course, and the double-slit experiment has since been conducted in various ways under various conditions. Others have shown that electrons and atoms and molecules exhibit the same type of behavior. In this new effort, the researchers have taken the experiment to a new level by using nothing but molecules, single atoms and lasers. In the original double-slit experiment, the light passed through both slits in a superposition of trajectories. In this new method, there is only one slit, but it is in a superposition of positions.

Part 1

Comment by Dr. Krishna Kumari Challa on November 27, 2021 at 11:17am

COVID-19 : Measuring viral RNA to predict which patients will die

The amount of a SARS-CoV-2 genetic material—viral RNA—in the blood is a reliable indicator in detecting which patients will die of the disease, a team  of researchers has found.

In this study, scientists were able to determine which biomarkers are predictors of mortality in the 60 days following the onset of symptoms. They have successfully developed and validated a statistical model based on one blood biomarker, viral RNA.  Several biomarkers have been identified in other studies, but juggling the profusion of parameters is not possible in a clinical setting and hinders doctors' ability to make quick medical decisions.

Using blood samples collected from 279 patients during their hospitalization for COVID-19, ranging in degrees of severity from moderate to critical, the  team measured amounts of inflammatory proteins, looking for any that stood out.

At the same time, they measured the amounts of viral RNA and  the levels of antibodies targeting the virus. Samples were collected 11 days after the onset of symptoms and patients were monitored for a minimum of 60 days after that.

The goal: to test the hypothesis that immunological indicators were associated with increased mortality. Among all of the biomarkers they evaluated, they showed that the amount of viral RNA in the blood was directly associated with mortality and provided the best predictive response, once their model was adjusted for the age and sex of the patient. They even found that including additional biomarkers did not improve predictive quality.

It made no difference which hospital the patients were treated at, nor which period of the pandemic they fell into: in all cases, the predictive model worked. Now the researchers  want to put it to practical use.

Elsa Brunet-Ratnasingham et al, Integrated immunovirological profiling validates plasma SARS-CoV-2 RNA as an early predictor of COVID-19 mortality, Science Advances (2021). DOI: 10.1126/sciadv.abj5629. www.science.org/doi/10.1126/sciadv.abj5629

https://medicalxpress.com/news/2021-11-covid-viral-rna-patients-die...

Comment by Dr. Krishna Kumari Challa on November 27, 2021 at 9:58am

quantified the entropy produced by a system evolving in quantum superposition of processes with opposite time arrows. We found this most often results in projecting the system onto a well-defined time's direction, corresponding to the most likely process of the two. And yet, when small amounts of entropy are involved (for instance, when there is so little toothpaste spilled that one could see it being reabsorbed into the tube), then one can physically observe the consequences of the system having evolved along the forward and backward temporal directions at the same time.

Aside from the fundamental feature that time itself might not be well-defined, the work also has practical implications in quantum thermodynamics. Placing a quantum system in a superposition of alternative time's arrows could offer advantages in the performance of thermal machines and refrigerators.

Although time is often treated as a continuously increasing parameter, this study shows the laws governing its flow in quantum mechanical contexts are much more complex. This may suggest that we need to rethink the way we represent this quantity in all those contexts where quantum laws play a crucial role.

Quantum superposition of thermodynamic evolutions with opposing time's arrows, Communications Physics (2021). DOI: 10.1038/s42005-021-00759-1

https://phys.org/news/2021-11-quantum-realm.html?utm_source=nwlette...

Part 2

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Comment by Dr. Krishna Kumari Challa on November 27, 2021 at 9:03am

In the quantum realm, not even time flows as you might expect

A team of physicists has shown how quantum systems can simultaneously evolve along two opposite time arrows—both forward and backward in time.

The study, published in the latest issue of Communications Physics, necessitates a rethink of how the flow of time is understood and represented in contexts where quantum laws play a crucial role.

For centuries, philosophers and physicists have been pondering the existence of time. Yet, in the classical world, our experience seems to extinguish any doubt that time exists and goes on. Indeed, in nature, processes tend to evolve spontaneously from states with less disorder to states with more disorder, and this propensity can be used to identify an arrow of time. In physics, this is described in terms of 'entropy', which is the physical quantity defining the amount of disorder in a system.

If a phenomenon produces a large amount of entropy, observing its time-reversal is so improbable as to become essentially impossible. However, when the entropy produced is small enough, there is a non-negligible probability of seeing the time-reversal of a phenomenon occur naturally.

An example. If we were shown our toothpaste moving from the toothbrush back into its tube, we would be in no doubt it was a rewinded recording of our day. However, if we squeezed the tube gently so only a small part of the toothpaste came out, it would not be so unlikely to observe it re-entering the tube, sucked in by the tube's decompression.

The authors of this study applied this idea to the quantum realm, one of whose peculiarities is the principle of quantum superposition, according to which if two states of a quantum system are both possible, then that system can also be in both states at the same time.

Extending this principle to time's arrows, it results that quantum systems evolving in one or the other temporal direction (the toothpaste coming out of or going back into the tube), can also find themselves evolving simultaneously along both temporal directions.

"Although this idea seems rather nonsensical when applied to our day-to-day experience, at its most fundamental level, the laws of the universe are based on quantum-mechanical principles. This begs the question of why we never encounter these superpositions of time flows in nature.

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