Scientists Break the Direction of Time Down To the Cellular Level In Mind-Bending Study

A new study looks at interactions between microscopic neurons in salamanders to understand how the “arrow of time” is biologically generated. Motherboard reports: The second law of thermodynamics says that everything tends to move from order to disorder, a process known as entropy that defines the arrow of time. A stronger arrow of time means it would be harder for a system to go back to a more ordered state. “Everything that we perceive as a difference between the past and the future stems fundamentally from that one principle about the universe,” said Christopher Lynn, the lead author of the study. Lynn said that his motivation for the study was “to understand how the arrows of time we see in life” fit into this larger idea of entropy on the scale of the entire universe.

Using previously done research on salamanders, Lynne and colleagues at City University of New York and Princeton examined how the arrow of time is represented in interactions between the amphibians’ neurons in response to watching a movie. Their research is soon to be published in the journal Physical Review Letters. On one hand, it’s somewhat obvious that an arrow of time would be biologically produced. “To be alive, almost, you have to have an arrow of time because you develop from a baby to an adult, and you’re constantly moving and taking in stimuli,” Lynne said. Indeed, entropy here is irreversible — you cannot go back. What the team found was anything but intuitive, however.

Lynne and colleagues looked at a separate 2015 study where researchers had salamanders watch two different movies. One depicted a scene of fish swimming around, similar to what a salamander might experience in everyday life. As in the real world, the video had a clear arrow of time — that is, if you watched it in reverse, it would look different than if you played it forwards. The other video contained only a gray screen with a black, horizontal bar in the middle of the screen, which moved quickly up and down in a random, jittery way. This video didn’t have an obvious arrow of time. A major question for the researchers was if they could pick out signs of “local irreversibility” in interactions between small groups of retinal neurons in response to this stimulus. Would interactions with irreversibility — they would look different if played in reverse, having an “arrow of time” — present in simpler or more complex interactions between neurons? “You can go look at a system and you can ask: are the more complicated interactions strongly producing the arrow of time, or is it the simpler dynamics?” said Lynn.

The researchers found that the interactions between simple pairs of neurons primarily determined the arrow of time, no matter which movie the salamanders watched. In fact, the authors found a stronger arrow of time for the neurons when salamanders watched the video with the gray screen and black bar — in other words, the video without an arrow of time in its content elicited a greater arrow of time in the neurons. “We naively thought that if the stimulus has a stronger arrow of time, that would show up on your retina,” said Lynn. “But it was the opposite. So that’s why it was surprising to us.” While the researchers can’t say for sure why this is, Lynn said that it might be because salamanders are more used to seeing something like the fish movie, and processing the more artificial movie took greater energy. In a more disordered system, which would have a greater arrow of time, more energy is consumed. “Being alive will still define an arrow of time,” Lynne said, no matter the stimulus.

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Psilocybin Therapy Sharply Reduces Excessive Drinking, Small Study Shows

A small study on the therapeutic effects of using psychedelics to treat alcohol use disorder found that just two doses of psilocybin magic mushrooms paired with psychotherapy led to an 83 percent decline in heavy drinking among the participants. Those given a placebo reduced their alcohol intake by 51 percent. From a report: By the end of the eight-month trial, nearly half of those who received psilocybin had stopped drinking entirely compared with about a quarter of those given the placebo, according to the researchers. The study, published Wednesday in JAMA Psychiatry, is the latest in a cascade of new research exploring the benefits of mind-altering compounds to treat a range of mental health problems, from depression, anxiety and post-traumatic stress disorder to the existential dread experienced by the terminally ill.

Although most psychedelics remain illegal under federal law, the Food and Drug Administration is weighing potential therapeutic uses for compounds like psilocybin, LSD and MDMA, the drug better known as Ecstasy. Dr. Michael Bogenschutz, director at NYU Langone Center for Psychedelic Medicine and the study’s lead investigator, said the findings offered hope for the nearly 15 million Americans who struggle with excessive drinking — roughly 5 percent of all adults. Excessive alcohol use kills an estimated 140,000 people each year.

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Physicists Discover a ‘Family’ of Robust, Superconducting Graphene Structures

In 2018, MIT researchers found that if two graphene layers are stacked at a very specific “magic” angle, the twisted bilayer structure could exhibit robust superconductivity, a widely sought material state in which an electrical current can flow through with zero energy loss. Now the team reports that […] four and five graphene layers can be twisted and stacked at new magic angles to elicit robust superconductivity at low temperatures. Phys.Org reports: This latest discovery, published this week in Nature Materials, establishes the various twisted and stacked configurations of graphene as the first known “family” of multilayer magic-angle superconductors. The team also identified similarities and differences between graphene family members. The findings could serve as a blueprint for designing practical, room-temperature superconductors. If the properties among family members could be replicated in other, naturally conductive materials, they could be harnessed, for instance, to deliver electricity without dissipation or build magnetically levitating trains that run without friction.

In the current study, the team looked to level up the number of graphene layers. They fabricated two new structures, made from four and five graphene layers, respectively. Each structure is stacked alternately, similar to the shifted cheese sandwich of twisted trilayer graphene. The team kept the structures in a refrigerator below 1 kelvin (about -273 degrees Celsius), ran electrical current through each structure, and measured the output under various conditions, similar to tests for their bilayer and trilayer systems. Overall, they found that both four- and five-layer twisted graphene also exhibit robust superconductivity and a flat band. The structures also shared other similarities with their three-layer counterpart, such as their response under a magnetic field of varying strength, angle, and orientation.

These experiments showed that twisted graphene structures could be considered a new family, or class of common superconducting materials. The experiments also suggested there may be a black sheep in the family: The original twisted bilayer structure, while sharing key properties, also showed subtle differences from its siblings. For instance, the group’s previous experiments showed the structure’s superconductivity broke down under lower magnetic fields and was more uneven as the field rotated, compared to its multilayer siblings. The team carried out simulations of each structure type, seeking an explanation for the differences between family members. They concluded that the fact that twisted bilayer graphene’s superconductivity dies out under certain magnetic conditions is simply because all of its physical layers exist in a “nonmirrored” form within the structure. In other words, there are no two layers in the structure that are mirror opposites of each other, whereas graphene’s multilayer siblings exhibit some sort of mirror symmetry. These findings suggest that the mechanism driving electrons to flow in a robust superconductive state is the same across the twisted graphene family.

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Engineers Demonstrate Quantum Integrated Circuit Made Up of Just a Few Atoms

Engineers in Sydney have demonstrated a quantum integrated circuit made up of just a few atoms. By precisely controlling the quantum states of the atoms, the new processor can simulate the structure and properties of molecules in a way that could unlock new materials and catalysts. New Atlas reports: The new quantum circuit comes from researchers at the University of New South Wales (UNSW) and a start-up company called Silicon Quantum Computing (SQC). It’s essentially made up of 10 carbon-based quantum dots embedded in silicon, with six metallic gates that control the flow of electrons through the circuit. It sounds simple enough, but the key lies in the arrangement of these carbon atoms down to the sub-nanometer scale. Relative to each other, they’re precisely positioned to mimic the atomic structure of a particular molecule, allowing scientists to simulate and study the structure and energy states of that molecule more accurately than ever before.

In this case, they arranged the carbon atoms into the shape of the organic compound polyacetylene, which is made up of a repeating chain of carbon and hydrogen atoms with an alternating pattern of single and double carbon bonds between them. To simulate those bonds, the team placed the carbon atoms at different distances apart. Next, the researchers ran an electrical current through the circuit to check whether it would match the signature of a natural polyacetylene molecule — and sure enough, it did. In other tests, the team created two different versions of the chain by cutting bonds at different places, and the resulting currents matched theoretical predictions perfectly. The significance of this new quantum circuit, the team says, is that it could be used to study more complicated molecules, which could eventually yield new materials, pharmaceuticals, or catalysts. This 10-atom version is right on the limit of what classical computers can simulate, so the team’s plans for a 20-atom quantum circuit would allow for simulation of more complex molecules for the first time. The research has been published in the journal Nature.

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Government Scientists Discover Biggest Bacteria Ever, Visible To Naked Eye

An anonymous reader quotes a report from Motherboard: Scientists have discovered a bacteria with cells that measure a full centimeter in length, an astonishing size that makes it by far the largest bacterial species ever found and even “challenges our concept of a bacterial cell,” reports a new study. Bacteria are an extraordinarily diverse group of organisms that have inhabited Earth for billions of years and have evolved to occupy a dizzying variety of niches. Still, almost all of these microbes are composed of simple cells that measure about two microns in diameter, which is about 40 times smaller than a strand of human hair.

Thiomargarita magnifica, a bacteria discovered on sunken red mangrove leaves in Guadeloupe, Lesser Antilles, has blown this standard scale out of the water. The species has evolved filamentary cells that are “larger than all other known giant bacteria by ~50-fold,” making them “visible to the naked eye,” according to a study published on Thursday in Science.
Scientists led by Jean-Marie Volland, a marine biologist who holds joint appointments at the Laboratory for Research in Complex Systems and the Joint Genome Institute (JGI), a U.S. Department of Energy office at Lawrence Berkeley National Laboratory, suspect that this record-breaking adaptation is partly due to the astonishing number of duplicated genes wielded by T. magnifica, an ability that is known as polyploidy. […]

The results revealed that these bacteria contain DNA clusters in their cells, which are located in compartments bordered by membranes that the team called “pepins.” These organized pepins provide a stark contrast to the free-floating DNA seen in the cells of most bacteria. In addition, the team’s genetic sequencing revealed that T. magnifica contains hundreds of thousands of genome copies that are dispersed across the cell, adding up to about three times the number of genes in most bacteria, which is an extreme example of polyploidy. “These cellular features likely allow the organism to grow to an unusually large size and circumvent some of the biophysical and bioenergetic limitations on growth,” Volland and his colleagues said.

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Physicists Say They’ve Built an Atom Laser That Can Run ‘Forever’

A new breakthrough has allowed physicists to create a beam of atoms that behaves the same way as a laser, and that can theoretically stay on “forever.” ScienceAlert reports: At the root of the atom laser is a state of matter called a Bose-Einstein condensate, or BEC. A BEC is created by cooling a cloud of bosons to just a fraction above absolute zero. At such low temperatures, the atoms sink to their lowest possible energy state without stopping completely. When they reach these low energies, the particles’ quantum properties can no longer interfere with each other; they move close enough to each other to sort of overlap, resulting in a high-density cloud of atoms that behaves like one ‘super atom’ or matter wave. However, BECs are something of a paradox. They’re very fragile; even light can destroy a BEC. Given that the atoms in a BEC are cooled using optical lasers, this usually means that a BEC’s existence is fleeting.

Atom lasers that scientists have managed to achieve to date have been of the pulsed, rather than continuous variety; and involve firing off just one pulse before a new BEC needs to be generated. In order to create a continuous BEC, a team of researchers at the University of Amsterdam in the Netherlands realized something needed to change. “In previous experiments, the gradual cooling of atoms was all done in one place. In our setup, we decided to spread the cooling steps not over time, but in space: we make the atoms move while they progress through consecutive cooling steps,” explained physicist Florian Schreck. “In the end, ultracold atoms arrive at the heart of the experiment, where they can be used to form coherent matter waves in a BEC. But while these atoms are being used, new atoms are already on their way to replenish the BEC. In this way, we can keep the process going — essentially forever.” The research has been published in the journal Nature.

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Rutgers Scientist Develops Antimicrobial, Plant-Based Food Wrap Designed To Replace Plastic

Aiming to produce environmentally friendly alternatives to plastic food wrap and containers, a Rutgers scientist has developed a biodegradable, plant-based coating that can be sprayed on foods, guarding against pathogenic and spoilage microorganisms and transportation damage. From a report: Their article, published in the science journal Nature Food, describes the new kind of packaging technology using the polysaccharide/biopolymer-based fibers. Like the webs cast by the Marvel comic book character Spider-Man, the stringy material can be spun from a heating device that resembles a hair dryer and “shrink-wrapped” over foods of various shapes and sizes, such as an avocado or a sirloin steak. The resulting material that encases food products is sturdy enough to protect bruising and contains antimicrobial agents to fight spoilage and pathogenic microorganisms such as E. coli and listeria.

The research paper includes a description of the technology called focused rotary jet spinning, a process by which the biopolymer is produced, and quantitative assessments showing the coating extended the shelf life of avocados by 50 percent. The coating can be rinsed off with water and degrades in soil within three days, according to the study. […] The paper describes how the new fibers encapsulating the food are laced with naturally occurring antimicrobial ingredients — thyme oil, citric acid and nisin. Researchers in the Demokritou research team can program such smart materials to act as sensors, activating and destroying bacterial strains to ensure food will arrive untainted. This will address growing concern over food-borne illnesses as well as lower the incidence of food spoilage […].

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Why Chemists Can’t Quit Palladium

A retracted paper highlights chemistry’s history of trying to avoid the expensive, toxic — but necessary — catalyst. From a report: It’s hard to find a place on Earth untouched by palladium. The silvery-white metal is a key part of catalytic converters in the world’s 1.4 billion cars, which spew specks of palladium into the atmosphere. Mining and other sources add to this pollution. As a result, traces of palladium show up in some of the most remote spots on Earth, from Antarctica to the top of the Greenland ice sheet. Palladium is also practically indispensable for making drugs. That’s because catalysts with palladium atoms at their core have an unmatched ability to help stitch together carbon –carbon bonds. This kind of chemical reaction is key to building organic molecules, especially those used in medications.

“Every pharmaceutical we produce at some point or another has a palladium-catalysed step in it,” says Per-Ola Norrby, a pharmaceutical researcher at drug giant AstraZeneca in Gothenburg, Sweden. Palladium-catalysed reactions are so valuable that, in 2010, their discoverers shared a Nobel prize. But despite its versatility, chemists are trying to move away from palladium. The metal is more expensive than gold, and molecules that contain palladium can also be extremely toxic to humans and wildlife. Chemical manufacturers have to separate out all traces of palladium from their products and carefully dispose of the hazardous waste, which adds extra expense. Thomas Fuchb, a medicinal chemist at the life-sciences company Merck in Darmstadt, Germany, gives the example of a reaction to make 3 kilograms of a drug molecule for which the ingredients cost US$250,000. The palladium catalyst alone adds $100,000; purifying it out of the product another $30,000.

Finding less-toxic alternatives to the metal could help to reduce environmental harm from palladium waste and move the chemicals industry towards ‘greener’ reactions, says Tianning Diao, an organometallic chemist at New York University. Researchers hope to swap palladium for more common metals, such as iron and nickel, or invent metal-free catalysts that sidestep the issue altogether. Several times in the past two decades, researchers have reported finding palladium-free catalysts. But in what has become a recurring pattern for the field, each heralded discovery turned out to be a mistake.

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Signs Are Not Enough To Save Beachgoers from Deadly Currents

Keeping people out of rip currents is more about reading human behavior than reading warning signs. From a report: Worldwide, rips cause hundreds of drownings and necessitate tens of thousands of rescues every year. In Australia, where 85 percent of the population lives within an hour’s drive of the coast, rips cause more fatalities than floods, cyclones, and shark attacks combined. In 1938, one of the country’s most popular beaches, Sydney’s Bondi Beach, was the site of an infamous rip-current tragedy: within minutes, roughly 200 swimmers were swept away by a rip, leaving 35 people unconscious and five dead. More often, however, rips take one life at a time, garnering little media attention. For many casual beach visitors, the toll of rip currents goes unnoticed. […] Although almost three-quarters of beach users said they knew what a rip current is, only 54 percent could correctly define it. In addition, only half of the people she surveyed remembered seeing either the warning signs or the colored flags denoting surf conditions that were posted on or near the main access point to each beach. An even smaller percentage could recall what color the flags had been — green for calm, yellow for moderate, or red for dangerous conditions. “I was genuinely shocked,” Locknick says.

[…] Part of the challenge of preventing rip-related drownings stems from the lack of a simple method to escape them. Rip currents form when waves pile water near the shoreline. The water then gushes back out to sea, taking the path of least resistance. It might flow along channels carved in between sandbars or next to solid structures, such as jetties or rocky headlands. These types of rips can stick around year after year. Others are more erratic, creating fleeting bursts of seaward-flowing water on smooth, open beaches. People often mislabel rip currents as undertows or rip tides. Rip currents are not caused by tides, however, and undertows are a different, weaker current, formed when water pushed onto the beach moves back offshore along the seabed. Some telltale signs of a rip include a streak of churned-up, sandy water or a dark, flat gap between breaking waves.

It’s not surprising that rip currents are often misunderstood by the public because, for decades, beach-safety experts also had an oversimplified perception of their mechanics. In some of the earliest research on rips in the mid-20th century, American scientists watched sticks, pieces of kelp, and volleyballs float out to sea and described lanes of flowing water extending more than 300 meters offshore. This work formed the basis for the popular view of rip currents as jets flowing perpendicular to the beach, shooting out past the surf. To escape the river of current, experts recommended that bathers swim parallel to the beach — a message once broadcast through education campaigns and warning signs in the United States and Australia. As it turns out, that approach may not always work.

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Short-Sightedness Was Rare. In Asia, It Is Becoming Ubiquitous

Researchers have found that being outside drastically reduces the risk of developing short-sightedness. From a report: In the early 1980s Taiwan’s army realised it had a problem. More and more of its conscripts seemed to be short-sighted, meaning they needed glasses to focus on distant objects. “They were worried that if the worst happened [ie, an attack by China] their troops would be fighting at a disadvantage,” says Ian Morgan, who studies myopia at Australian National University, in Canberra. An island-wide study in 1983 confirmed that around 70% of Taiwanese school leavers needed glasses or contact lenses to see properly. These days, that number is above 80%. But happily for Taiwan’s generals, the military disparity has disappeared. Over the past few decades myopia rates have soared across East Asia (see chart 1 in the linked story). In the 1960s around 20-30% of Chinese school-leavers were short-sighted. These days they are just as myopic as their cousins across the straits, with rates in some parts of China running at over 80%.

Elsewhere on the continent things are even worse. One study of male high-school leavers in Seoul found 97% were short-sighted. Hong Kong and Singapore are not far behind. And although the problem is worst in East Asia, it is not unique to it. Reliable numbers for America and Europe are harder to come by. But one review article, published in 2015, claimed a European rate of between 20% and 40% — an order of magnitude higher than that which people working in the field think is the “natural,” background rate. For most of those affected, myopia is a lifelong, expensive nuisance. But severe myopia can lead to untreatable vision loss, says Annegret Dahlmann-Noor, a consultant ophthalmologist at Moorfields Eye Hospital, in London. A paper published in 2019 concluded that each one-dioptre worsening in myopia was associated with a 67% increase in prevalence of myopic maculopathy, an untreatable condition that causes blindness. (A dioptre is a measure of a lens’s focusing power.) In some parts of East Asia, 20% of young people have severe myopia, defined as -6 dioptres or worse (see chart 2 in linked story). “This is storing up a big problem for the coming decades,” says Kathryn Rose, head of orthoptics at the University of Technology, Sydney.

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