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Comment by Dr. Krishna Kumari Challa on October 31, 2022 at 11:37am

Physicists see light waves moving through a metal

When we encounter metals in our day-to-day lives, we perceive them as shiny. That's because common metallic materials are reflective at visible light wavelengths and will bounce back any light that strikes them. While metals are well suited to conducting electricity and heat, they aren't typically thought of as a means to conduct light.

But in the burgeoning field of quantum materials, researchers are increasingly finding examples that challenge expectations about how things should behave. In new research published in Science Advances, a research team describes a metal capable of conducting light. These results defy our daily experiences and common conceptions.

Researchers have been  exploring the optical properties of a semimetal material known as ZrSiSe. They  showed that ZrSiSe shares electronic similarities with graphene, the first so-called Dirac material discovered in 2004. ZrSiSe, however, has enhanced electronic correlations that are rare for Dirac semimetals.

Whereas graphene is a single, atom-thin layer of carbon, ZrSiSe is a three-dimensional metallic crystal made up of layers that behave differently in the in-plane and out-of-plane directions, a property known as anisotropy. It's sort of like a sandwich: One layer acts like a metal while the next layer acts like an insulator. Whereas graphene is a single, atom-thin layer of carbon, ZrSiSe is a three-dimensional metallic crystal made up of layers that behave differently in the in-plane and out-of-plane directions, a property known as anisotropy. "It's sort of like a sandwich: One layer acts like a metal while the next layer acts like an insulator.

They observed such zigzag movement of light, so-called hyperbolic waveguide modes, through ZrSiSe samples of varying thicknesses. Such waveguides can guide light through a material and here, result from photons of light mixing with electron oscillations to create hybrid quasiparticles called plasmons.

Although the conditions to generate plasmons that can propagate hyperbolically are met in many layered metals, it is the unique range of electron energy levels, called electronic band structure, of ZrSiSe that allowed the team to observe them in this material.

Yinming Shao et al. Infrared plasmons propagate through a hyperbolic nodal metal. Science Advances (2022). DOI: 10.1126/sciadv.add6169

Comment by Dr. Krishna Kumari Challa on October 29, 2022 at 8:38am

Heat waves driven by climate change have cost global economy trillions since the 1990s

Massive economic losses due to sweltering temperatures brought on by human-caused climate change are not just a problem for the distant future. A study in the journal Science Advances has found that more severe heat waves resulting from global warming have already cost the world economy trillions of dollars since the early 1990s—with the world's poorest and lowest carbon-emitting nations suffering the most.

Researchers combined newly available, in-depth economic data for regions worldwide with the average temperature for the hottest five-day period—a commonly used measurement of heat intensity—for each region in each year. They found that from 1992–2013, heat waves statistically coincided with variations in economic growth and that an estimated $16 trillion was lost to the effects of high temperatures on human health, productivity and agricultural output.

The findings stress the immediate need for policies and technologies that protect people during the hottest days of the year, particularly in the world's warmest, most economically vulnerable nations, the researchers report.

Christopher W. Callahan et al, Globally unequal effect of extreme heat on economic growth, Science Advances (2022). DOI: 10.1126/sciadv.add3726. www.science.org/doi/10.1126/sciadv.add3726

Comment by Dr. Krishna Kumari Challa on October 29, 2022 at 7:01am

The study also shows remarkable similarities, or convergence, among placental mammals with most mammal skull shapes evolving in much the same way throughout the fossil record. The biggest exceptions are whales and rodents.

What makes mammals evolve fast?

A key aim of this study is to better predict how different species may respond to rapid changes in their environment—the kind we are likely to see throughout the current planetary emergency. To do this the team investigated the characteristics of mammals that evolve fast and found the key influencers to be habitat, social behaviors, diet, parental care and time of activity.

Social structures hugely differentiate the rate which mammals evolve. Mammals which are social evolve much faster than those that are solitary. This is easily witnessed in ungulates which have evolved horns and antlers for fighting and social display. Mammals that live in aquatic environments, including whales but also manatees, seals and walruses are also fast evolvers. Herbivores also evolve faster than carnivores, probably because they track changes in plants and the environment more closely than meat eaters do.

Parental care also seems to be a big factor slowing down the speed of evolution. Precocial animals that require little primary care, such as horses and antelopes, evolve a lot faster than altricial mammals that are reliant on caregivers in infancy, such as primates. When animals are active also makes a difference, with species with a strict schedule, whether nocturnal or diurnal, evolving slower than animals without a fixed activity pattern.

Unexpectedly, the groups of mammals with the most species, rodents and bats, don't appear to evolve very quickly, suggesting that diversity in shape and diversity in number aren't closely linked in mammals.

Anjali Goswami et al, Attenuated evolution of mammals through the Cenozoic, Science (2022). DOI: 10.1126/science.abm7525

Part 2

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Comment by Dr. Krishna Kumari Challa on October 29, 2022 at 6:59am

Social mammals evolve faster than solitary ones, according to new study of evolution

A groundbreaking new research project has analyzed the evolution of the placental mammal skull using 3D scans of 322 specimens housed in more than 20 international museum collections, and crafted a new model of how mammals diversified based on the emerging patterns.

By gathering data on the skulls of all major groups of placental mammals, both extinct and extant, the team of researchers have gained a unique look across time and taxa to trace the adaptive radiation (rapid evolution which fills a variety of ecological niches) of mammals and decipher what drove their incredible rise in the wake of the dinosaur extinction.

Although the earliest mammals existed alongside dinosaurs, they were relatively constrained in their diversity, with the largest mammals of the Mesozoic Era growing to be the size of a small dog. However, immediately after the extinction of the dinosaurs there is an incredible explosion of diversity among placental mammals with the earliest ancestors of today's living groups appearing in the fossil record within a few 100,000 years of this event.

However, this new study shows that after the initial burst of mammal diversification, the pace of evolution quickly slows down. Later bursts of faster evolution do occur, but their impacts get smaller and smaller through time, and never match the speed of that first peak. While uncertainty in the exact timing of these later bursts makes it is difficult to attribute them to specific events, they are likely caused by periods of rapid or sustained climate change and the global cooling through the Cenozoic era.

Part 1

Comment by Dr. Krishna Kumari Challa on October 28, 2022 at 12:55pm

The link between gut bacteria and rheumatoid arthritis

Researchers have discovered that a unique bacteria found in the gut could be responsible for triggering rheumatoid arthritis (RA) in people already at risk for the autoimmune disease.

They established that  they can identify people who are at risk for RA based on serologic markers, and that these markers can be present in the blood for many years before diagnosis. 

The researchers  took the antibodies created by immune cells  from individuals whose blood markers showed they were at risk for the disease and mixed them with the feces of the at-risk individuals to find the bacteria that were tagged by the antibodies.

To further test their hypothesis, the researchers used animal models to host the newly discovered bacteria. Those experiments showed that not only did the bacteria cause the animal models to develop the blood markers found in individuals at risk for RA; but some of the models showed development of full-blown RA as well.

They confirmed that the T cells in the blood of people with RA will respond to these bacteria, but people who are otherwise healthy do not respond to these bacteria. 

If the unique species of bacteria is indeed driving the immune response that leads to RA in individuals already at risk for the disease. It might be possible to target the bacteria with medication to prevent that response from happening.

 Meagan E. Chriswell et al, Clonal IgA and IgG autoantibodies from individuals at risk for rheumatoid arthritis identify an arthritogenic strain of Subdoligranulum, Science Translational Medicine (2022). DOI: 10.1126/scitranslmed.abn5166

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Comment by Dr. Krishna Kumari Challa on October 28, 2022 at 9:03am

1. Brassard, Gilles; Cleve, Richard; Tapp, Alain (1999). "Cost of Exactly Simulating Quantum Entanglement with Classical Communication". Physical Review Letters. 83 (9): 1874–1877. arXiv:quant-ph/9901035. Bibcode:1999PhRvL..83.1874B. doi:10.1103/PhysRevLett.83.1874. S2CID 5837965.
2. ^ Brassard, Gilles; Broadbent, Anne; Tapp, Alain (2003). "Multi-party Pseudo-Telepathy". Algorithms and Data Structures. Lecture Notes in Computer Science. Vol. 2748. pp. 1–11. arXiv:quant-ph/0306042. doi:10.1007/978-3-540-45078-8_1. ISBN 978-3-540-40545-0. S2CID 14390319.

Part 2

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Birds getting smaller, 'wingier' as planet warms, research finds

A UCLA-led study published today reveals that migratory birds across North America are getting smaller, a change the researchers attribute to the rapidly warming climate.

Comment by Dr. Krishna Kumari Challa on October 28, 2022 at 9:03am

Quantum pseudo-telepathy is the fact that in certain Bayesian games with asymmetric information, players who have access to a shared physical system in an entangled quantum state, and who are able to execute strategies that are contingent upon measurements performed on the entangled physical system, are able to achieve higher expected payoffs in equilibrium than can be achieved in any mixed-strategy Nash equilibrium of the same game by players without access to the entangled quantum system.

In their 1999 paper,[1] Gilles Brassard, Richard Cleve and Alain Tapp demonstrated that quantum pseudo-telepathy allows players in some games to achieve outcomes that would otherwise only be possible if participants were allowed to communicate during the game.

This phenomenon came to be referred to as quantum pseudo-telepathy,[2] with the prefix pseudo referring to the fact that quantum pseudo-telepathy does not involve the exchange of information between any parties. Instead, quantum pseudo-telepathy removes the need for parties to exchange information in some circumstances.

By removing the need to engage in communication to achieve mutually advantageous outcomes in some circumstances, quantum pseudo-telepathy could be useful if some participants in a game were separated by many light years, meaning that communication between them would take many years. This would be an example of a macroscopic implication of quantum non-locality.

Quantum pseudo-telepathy is generally used as a thought experiment to demonstrate the non-local characteristics of quantum mechanics. However, quantum pseudo-telepathy is a real-world phenomenon which can be verified experimentally. It is thus an especially striking example of an experimental confirmation of Bell inequality violations.

Comment by Dr. Krishna Kumari Challa on October 27, 2022 at 9:44am

Doctors say 'fossil fuel addiction' kills, starves millions

Extreme weather from climate change triggered hunger in nearly 100 million people and increased heat deaths by 68% in vulnerable populations worldwide as the world's "fossil fuel addiction" degrades public health each year, doctors reported in a new study.

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Earth on track to warm above 2 degrees Celsius despite climate action

Government plans to cut greenhouse gas emissions aren't enough to avoid catastrophic global warming, with the planet on track to heat up between 2.1 and 2.9 degrees Celsius by the end of the century compared to pre-industrial times, according to a new report from the United Nations Framework Convention on Climate Change.

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Bacteria could last on Mars for 280 million years

Researchers have discovered that certain hardy bacteria could survive in the hostile Martian conditions for millions of years, by testing the ability of a selection of ‘extremophile’ microbes — which can live in harsh environments — to survive in cold, radioactive conditions similar to those on Mars. The team found that, when dried and frozen, the Deinococcus radiodurans microbe could survive under the surface of Mars for 280 million years. The findings increase the chance that life could be found in future samples from the red planet.

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The scientists trying to rewind ageing

Research laboratories and biotech companies are applying cellular-reprogramming techniques to animals to see whether they can make them more youthful. The methods are based on the Nobel-prizewinning discovery in 2006 by Japanese scientist Shinya Yamanaka, who turned adult cells into stem cells that resemble embryonic cells. Some scientists say they have found evidence of the procedure rejuvenating the animals and their organs. “We think we can turn back the clock,” Richard Klausner, chief scientist of the company Altos Labs, told an audience at an event in June. Investors are throwing billions into these initiatives, despite a lack of consensus among scientists on what causes ageing and when ageing even begins.

Comment by Dr. Krishna Kumari Challa on October 27, 2022 at 9:37am

Scientists warn in report that climate change has pushed Earth to 'code red'

Writing in the journal BioScience, an international coalition of  researchers says in a report published today that the Earth's vital signs have reached "code red" and that "humanity is unequivocally facing a climate emergency."

In the special report, "World Scientists' Warning of a Climate Emergency 2022," the authors note that 16 of 35 planetary vital signs they use to track climate change are at record extremes. The report's authors share new data illustrating increasing frequency of extreme heat events, rising global tree cover loss because of fires, and a greater prevalence of the mosquito-borne dengue virus. Further, they note that atmospheric carbon dioxide levels have reached 418 parts per million, the highest on record.

The report follows by five years the "World Scientists' Warning to Humanity: A Second Notice" published by Ripple and colleagues in BioScience and co-signed by more than 15,000 scientists in 184 countries.

As we can see by the annual surges in climate disasters, we are now in the midst of a major climate crisis, with far worse to come if we keep doing things the way we've been doing them, say the scientists. 

The report points out that in the three decades since more than 1,700 scientists signed the original "World Scientists' Warning to Humanity" in 1992, global greenhouse gas emissions have increased by 40%.

As Earth's temperatures are creeping up, the frequency or magnitude of some types of climate disasters may actually be leaping up.

William J Ripple et al, World Scientists' Warning of a Climate Emergency 2022, BioScience (2022). DOI: 10.1093/biosci/biac083

William J. Ripple et al, World Scientists' Warning to Humanity: A Second Notice, BioScience (2017) DOI: 10.1093/biosci/bix125

Comment by Dr. Krishna Kumari Challa on October 27, 2022 at 9:13am

Scientists discover exotic quantum state at room temperature

For the first time, physicists have observed novel quantum effects in a topological insulator at room temperature. This breakthrough, published as the cover article of the October issue of Nature Materials, came when  scientists explored a topological material based on the element bismuth.

The scientists have used topological insulators to demonstrate quantum effects for more than a decade, but this experiment is the first time these effects have been observed at room temperature. Typically, inducing and observing quantum states in topological insulators requires temperatures around absolute zero, which is equal to -459 degrees Fahrenheit (or -273 degrees Celsius).

This finding opens up a new range of possibilities for the development of efficient quantum technologies, such as spin-based electronics, which may potentially replace many current electronic systems for higher energy efficiency.

Nana Shumiya et al, Evidence of a room-temperature quantum spin Hall edge state in a higher-order topological insulator, Nature Materials (2022). DOI: 10.1038/s41563-022-01304-3

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