Comment

Comment by Dr. Krishna Kumari Challa on March 12, 2021 at 11:25am

Antarctic detector spots cosmic antineutrino

A huge neutrino detector in the Antarctic ice sheet might have seen the first evidence of a rare neutrino-interaction process called the Glashow resonance.

The IceCube Neutrino Observatory, buried in the deep ice near the Amundsen–Scott South Pole Station, observes eye-wateringly powerful neutrinos produced by sources such as active galactic nuclei and supernovae. The observatory detected a shower of secondary particles that look likely to have been caused by a collision between an electron antineutrino travelling close to th.... If confirmed by more observations, the finding provides further confirmation of the standard model of particle physics, proves the existence of cosmic antineutrinos and opens the door to a better understanding of the wild stuff going on in the cosmos.

https://www.nature.com/articles/d41586-021-00486-1?utm_source=Natur...

Comment by Dr. Krishna Kumari Challa on March 12, 2021 at 11:15am

Physicists measure smallest gravitational field yet

Physicists in Austria have measured the gravitational field from the smallest ever object: a gold sphere with a diameter of just 2 mm. Carried out using a miniature torsion balance, the measurement paves the way to even more sensitive gravitational probes that could reveal gravity’s quantum nature.

The latest work, in contrast, uses a gold sphere with a mass of just 92 mg as its source. Markus Aspelmeyer and Tobias Westphal of the Institute for Quantum Optics and Quantum Information in Vienna and colleagues positioned this mass a few millimetres away from another tiny gold sphere with about the same mass located at one end of a 4 cm-long glass rod. The rod was suspended at its centre via a silica fibre, while a third sphere at the far end of the rod acted as a counterbalance.

Such “torsion balances” have been used for more than 200 years to make precise measurements of gravity. The idea is that the source mass pulls the near end of the bar towards itself, causing the suspending fibre or wire to rotate. By measuring this rotation and balancing it against the stiffness of the wire, the strength of the gravitational interaction can be calculated. The fact that the bar moves horizontally means it is less exposed to the far larger gravitational field of the Earth.

A major challenge with such experiments is screening out noise. Aspelmeyer and colleagues did this by placing the balance in a vacuum to limit acoustic and thermal interference, while also grounding the source mass and placing a Faraday shield between it and the test mass to reduce electromagnetic interactions. In addition, they mainly collected data at night to minimize ambient sources of gravity. This is important because the gravitational attraction of the source mass is equivalent to the pull of a person standing 2.5 m from the experiment or a Vienna tram 50 m away.

To generate signals above the remaining noise, the researchers used a bending piezoelectric device to cyclically move the source towards and away from the test mass. Doing this at a fixed frequency (12.7 mHz) allowed them to look for a corresponding variation in the rotation of the balance – which they measured by bouncing a laser beam off a mirror below the silica fibre.

After repeating this process hundreds of times over a 13.5-hour period and then converting the time-series data into a frequency spectrum, Aspelmeyer and colleagues identified two clear signals above the background. These were the principle oscillation at 12.7 mHz and, at 25.4 mHz, the second harmonic generated by the gravitational field’s nonlinear variation in space. As the researchers point out, both harmonics were well above the resonant frequency of the oscillating balance and below the frequencies of readout noise.

https://www.nature.com/articles/s41586-021-03250-7.epdf?sharing_tok...

https://physicsworld.com/a/physicists-measure-smallest-gravitationa...

**

Comment by Dr. Krishna Kumari Challa on March 12, 2021 at 11:04am

Part 2 - extreme hot planets

In our study, we used publicly available data, taken by the Hubble Space Telescope, to obtain the eclipse spectrum of this planet.

We then used open-source software to extract the presence of molecules and found there were plenty of metals (made from molecules). This discovery is interesting as it was previously thought that these molecules would not be present at such extreme temperatures – they would be broken apart into smaller compounds.

Subject to the strong gravitational pull from its host star, Kelt-9 b is “tidally locked”, which means that the same face of the planet permanently faces the star. This results in a strong temperature difference between the planet’s day and night sides. As the eclipse observations probe the hotter day-side, we suggested that the observed molecules could in fact be dragged by dynamic processes from the cooler regions, such as the night-side or from deeper in the interior of the planet. These observations suggest that the atmospheres of these extreme worlds are ruled by complex processes that are poorly understood.

Kelt-9 b is interesting because of its inclined orbit of about 80 degrees. This suggests a violent past, with possible collisions, which in fact is also seen for many other planets of this class. It is most likely that this planet formed away from its parent star and that the collisions happened as it migrated inwards toward the star. This supports the theory that large planets tend to form away from their host star in proto-stellar disks – which give rise to solar systems – capturing gaseous and solid materials as they migrate toward their star.

https://theconversation.com/how-can-some-planets-be-hotter-than-sta...

Comment by Dr. Krishna Kumari Challa on March 12, 2021 at 11:03am

How can some planets be hotter than stars? We’ve started to unravel the mystery

Data from the Kepler mission has shown that large, gaseous exoplanets can orbit very close to their star – rather than far away from it, as is the case in our Solar System, causing them to reach temperatures exceeding 1,000K (727°C). These have been dubbed “hot” or “ultra-hot” Jupiters.

But how can hot, gaseous planets form and exist so close to their star? What kind of extreme physical processes happen here? Answers to those questions have large implications in our understanding of exoplanets and solar system planets. In our recent study, published in The Astrophysical Journal Letters, we have added another piece to the puzzle of planet formation and evolution.

The hottest exoplanet known so far is Kelt-9 b, which was discovered in 2016. Kelt-9 b orbits a star that is twice as hot as our Sun, at a distance ten times closer than Mercury orbits our star. It is a large gaseous exoplanet, with a radius 1.8 times that of Jupiter and temperatures reaching 5,000K. For comparison, this is hotter than 80% of all the stars in the universe and a similar temperature to our Sun.

In essence, hot Jupiters are a window into extreme physical and chemical processes. They offer an incredible opportunity to study physics in environmental conditions that are near impossible to reproduce on Earth. Studying them enhances our understanding of chemical and thermal processes, atmospheric dynamics and cloud formation. Understanding their origins can also help us improve planetary formation and evolution models.

To find out, we need to learn more about exoplanet compositions by observing their atmospheres.

There are two main methods to study exoplanet atmospheres. In the transit method, we can pick up stellar light that is filtered through the exoplanet’s atmosphere when it passes in front of its star, revealing the fingerprints of any chemical elements that exist there.

The other method to investigate a planet is during an “eclipse”, when it passes behind its host star. Planets also emit and reflect a small fraction of light, so by comparing the small changes in the total light when the planet is hidden and visible, we can extract the light coming from the planet.

Both types of observations are performed at different wavelengths, or colours, and since chemical elements and compounds absorb and emit at very specific wavelengths, a spectrum (light broken down by wavelength) can be produced for the planet to infer the composition of its atmosphere.

Comment by Dr. Krishna Kumari Challa on March 12, 2021 at 10:58am

Using softened wood to create electricity in homes

A multi-institutional team of researchers has found that it is possible to use a type of fungus to soften wood to the point that it could be used to generate electricity. In their paper published in the journal Science Advances, the group describes their process and how they tested it.

As the world works its way toward cleaner energy-producing systems, scientists seek novel approaches to producing electricity. One possibility is the use of piezoelectric devices that generate electricity by harnessing movement such as footsteps. In this new effort, the researchers have noted that much energy is wasted when people walk around. And while some have attempted to harness some of that energy with devices designed for shoes or legs, the researchers with this new effort wondered if it might be possible to add piezoelectrics to the floor to make use of that energy.

In studying the kinds of wood that are used to make floors, particularly in homes, the researchers noted that they do not have much give—a necessary component of an energy-harvesting system. To solve that problem, they found that applying a type of white rot fungus to pieces of balsa wood for a few weeks sped up the decaying process in a useful way. It made the wood spongier, which translated to give. When stepping on the wood, the researchers could feel it depress. They also found that after the wood returned to its former shape when pressure was removed.

To test their idea, the researchers treated a wooden veneer with the fungus and then added a piezoelectric device, which sent the power it produced through a wire attached to an LED light. The wood was then placed on a floor where people could walk on it. Each time they did so, the light came on. The researchers note that the amount of electricity generated was just 0.85 volts but the system could very easily be scaled up to include all the flooring in a home, generating enough electricity, perhaps, to power certain devices.

Jianguo Sun et al. Enhanced mechanical energy conversion with selectively decayed wood, Science Advances (2021). DOI: 10.1126/sciadv.abd9138

https://techxplore.com/news/2021-03-softened-wood-electricity-homes...

**

Comment by Dr. Krishna Kumari Challa on March 12, 2021 at 10:27am

How to spot deepfakes? Look at light reflection in the eyes

Computer scientists have developed a tool that automatically identifies deepfake photos by analyzing light reflections in the eyes.

The tool proved 94% effective with portrait-like photos in experiments described in a paper accepted at the IEEE International Conference on Acoustics, Speech and Signal Processing to be held in June in Toronto, Canada.

The cornea is almost like a perfect semisphere and is very reflective. So, anything that is coming to the eye with a light emitting from those sources will have an image on the cornea. The two eyes should have very similar reflective patterns because they're seeing the same thing. It's something that we typically don't typically notice when we look at a face.

When we look at something, the image of what we see is reflected in our eyes. In a real photo or video, the reflections on the eyes would generally appear to be the same shape and color.

However, most images generated by artificial intelligence—including generative adversary network (GAN) images—fail to accurately or consistently do this, possibly due to many photos combined to generate the fake image.

Now the researchers tool exploits this shortcoming by spotting tiny deviations in reflected light in the eyes of deepfake images.

While promising, this new technique has limitations.

For one, you need a reflected source of light. Also, mismatched light reflections of the eyes can be fixed during editing of the image. Additionally, the technique looks only at the individual pixels reflected in the eyes—not the shape of the eye, the shapes within the eyes, or the nature of what's reflected in the eyes.

Finally, the technique compares the reflections within both eyes. If the subject is missing an eye, or the eye is not visible, the technique fails.

Exposing GAN-generated Faces Using Inconsistent Corneal Specular Highlights. arXiv:2009.11924v2 [cs.CV] arxiv.org/abs/2009.11924

https://techxplore.com/news/2021-03-deepfakes-eyes.html?utm_source=...

Comment by Dr. Krishna Kumari Challa on March 12, 2021 at 10:14am

Classic math problem solved: Computer scientists have developed a s...

One of the most classic algorithmic problems deals with calculating the shortest path between two points. A more complicated variant of the problem is when the route traverses a changing network—whether this be a road network or the internet. For 40 years, researchers have sought an algorithm that provides an optimal solution to this problem. Now, computer scientist Christian Wulff-Nilsen of the University of Copenhagen and two research colleagues have come up with a recipe.

When heading somewhere new, most of us leave it to computer algorithms to help us find the best route, whether by using a car's GPS, or public transport and map apps on their phone. Still, there are times when a proposed route doesn't quite align with reality. This is because road networks, public transportation networks and other networks aren't static. The best route can suddenly be the slowest, e.g. because a queue has formed due to roadworks or an accident.

People probably don't think about the complicated math behind routing suggestions in these types of situations. The software being used is trying to solve a variant for the classic algorithmic "shortest path" problem, the shortest path in a dynamic network. For 40 years, researchers have been working to find an algorithm that can optimally solve this mathematical conundrum. Now, Christian Wulff-Nilsen of the University of Copenhagen's Department of Computer Science has succeeded in cracking the nut along with two colleagues.

The researchers represent a network as a so-called dynamic graph. In this context, a graph is an abstract representation of a network consisting of edges, roads for example, and nodes, representing intersections, for example. When a graph is dynamic, it means that it can change over time. The new algorithm handles changes consisting of deleted edges—for example, if the equivalent of a stretch of a road suddenly becomes inaccessible due to road work.

Traditional algorithms assume that a graph is static, which is rarely true in the real world. When these kinds of algorithms are used in a dynamic network, they need to be rerun every time a small change occurs in the graph—which wastes time.

Aaron Bernstein, et al. Near-Optimal Decremental SSSP in Dense Weighted Digraphs. arXiv:2004.04496v2 [cs.DS] arxiv.org/abs/2004.04496

https://techxplore.com/news/2021-03-classic-math-problem-scientists...

Comment by Dr. Krishna Kumari Challa on March 12, 2021 at 10:10am

The secrets of the best rainbows on Earth

Why Hawai'i the rainbow capital of the world

Rainbows are some of the most spectacular optical phenomena in the natural world

Hawai'i's location in the subtropical Pacific means the overall weather pattern is dominated by trade winds, with frequent rain showers and clear skies between the showers.

Businger outlines four additional factors affecting the prevalence of rainbows throughout the islands.

"At night a warm sea surface heats the atmosphere from below, while radiation to space cools cloud tops, resulting in deeper rain showers in the morning that produce rainbows in time for breakfast," said Businger.

Another critical factor in producing frequent rainbows is Hawai'i's mountains, which cause trade wind flow to be pushed up, forming clouds and producing rainfall. Without mountains, Hawai'i would be a desert with a scant 17 inches annual rainfall.

A third factor conducive to rainbow sightings is daytime heating, which drives island-scale circulations. During periods of lighter winds, showers form over the ridge crests over Oahu and Kauai in the afternoon, resulting in prolific rainbows as the sun sets.

Due to the remoteness of the Hawaiian Islands, the air is exceptionally clean and free of pollution, continental dust, and pollen. This is the fourth factor that contributes to the numerous bright rainbows with the full spectrum of colors.

Steven Businger, The Secrets of the Best Rainbows on Earth, Bulletin of the American Meteorological Society (2020). DOI: 10.1175/BAMS-D-20-0101.1

https://phys.org/news/2021-03-secrets-rainbows-earth.html?utm_sourc...

**

Comment by Dr. Krishna Kumari Challa on March 12, 2021 at 10:00am

Foodborne fungus impairs intestinal wound healing in Crohn's disease

Eating is a dangerous business. Naturally occurring toxins in food and potentially harmful foodborne microbes can do a number on our (injure) intestines, leading to repeated minor injuries. In healthy people, such damage typically heals in a day or two. But in people with Crohn's disease, the wounds fester, causing abdominal pain, bleeding, diarrhea and other unpleasant symptoms.

Crohn's is a subtype of inflammatory bowel disease. As the name suggests, it is driven by chronic inflammation in the digestive tract and primarily treated with immunosuppressive medications. Crohn's patients endure repeated cycles of gastrointestinal symptom flare-up and remission. During a flare, their digestive tracts are dotted with inflamed, open sores that can persist for weeks or even months.

Researchers discovered that a fungus found in foods such as cheese and processed meats can infect sites of intestinal damage in mice and people with Crohn's and prevent healing. Moreover, treating infected mice with antifungal medication eliminates the fungus and allows the wounds to heal.

The findings, published March 12 in the journal Science, suggest that antifungal drugs and dietary changes are potential new approaches to improving intestinal wound healing and reducing symptoms of Crohn's disease.

 U. Jain el al., "Debaryomyces is enriched in Crohn's disease intestinal tissue and impairs healing in mice," Science (2021). science.sciencemag.org/cgi/doi … 1126/science.abd0919

https://medicalxpress.com/news/2021-03-foodborne-fungus-impairs-int...

Comment by Dr. Krishna Kumari Challa on March 12, 2021 at 9:43am

Observing the birth of a quasiparticle

Over the past decades, physicists worldwide have been trying to gain a better understanding of non-equilibrium dynamics in quantum many-body systems. Some studies investigated what are known as quasiparticles, disturbances or entities in physical systems that exhibit behavior similar to that of particles.

Researchers at Aarhus University recently carried out a study investigating the non-equilibrium dynamics of a quantum impurity immersed in a bosonic environment. Their paper, published in Nature Physics, sheds light on the dynamical behavior of interacting many-body systems, while also improving the current understanding of how Bose polarons are formed.

Quasiparticles are extremely interesting, since they may consist of countless particles and their excitations.

The idea of quasiparticles was first introduced in the 1930s by physicist Lev Landau, who was trying to gain a better understanding of complex quantum systems. The experiments carried out now build on models created by Landau.

In their studies, the researchers prepared coherent superposition states of atoms in a Bose-Einstein condensate with a small impurity-state component using an interferometric technique. Subsequently, they monitored the evolution of these quantum superpositions and their transition into polaronic quasiparticles.

Remarkably, the researchers were able to observe the birth of a unique class of quasiparticles, called Bose polarons, for the very first time. While in the past several research groups detected signs of these quasiparticles in laboratory settings, so far observing their gradual formation over time proved highly challenging, mainly because the processes through which they are formed are exceedingly fast.

Non-equilibrium quantum dynamics and formation of the Bose polaron. Nature Physics(2021). DOI: 10.1038/s41567-021-01184-5.

Bipolarons in a Bose-Einstein condensate. Physical Review Letters(2018).
DOI: 10.1103/PhysRevLett.121.013401.

Observation of attractive and repulsive polarons in a Bose-Einstein condensate. Physical Review Letters(2016). DOI: 10.1103/PhysRevLett.117.055302.

Bose polarons in the strongly interacting regime. Physical Review Letters(2016). DOI: 10.1103/PhysRevLett.117.055301.

Bose polarons near quantum criticality. Science(2020). DOI: 10.1126/science.aax5850.

https://phys.org/news/2021-03-birth-quasiparticle.html?utm_source=n...

• ‹ Previous
• 1
• …
• 658
• 659
• 660
• 661
• 662
• …
• 1081
• Next ›
• Page