Physicists capture the sound of a 'perfect' fluid

For physicists, a perfect flow is more specific, referring to a fluid that flows with the smallest amount of friction, or viscosity, allowed by the laws of quantum mechanics. Such perfectly fluid behaviour is rare in nature, but it is thought to occur in the cores of neutron stars and in the soupy plasma of the early universe.

Now physicists have created a perfect fluid in the laboratory, and listened to how sound waves travel through it. The recording is a product of a glissando of sound waves that the team sent through a carefully controlled gas of elementary particles known as fermions. The pitches that can be heard are the particular frequencies at which the gas resonates like a plucked string.

The researchers analyzed thousands of sound waves traveling through this gas, to measure its "sound diffusion," or how quickly sound dissipates in the gas, which is related directly to a material's viscosity, or internal friction.

Surprisingly, they found that the fluid's sound diffusion was so low as to be described by a "quantum" amount of friction, given by a constant of nature known as Planck's constant, and the mass of the individual fermions in the fluid.

This fundamental value confirmed that the strongly interacting fermion gas behaves as a perfect fluid, and is universal in nature. The results, published today in the journal Science, demonstrate the first time that scientists have been able to measure sound diffusion in a perfect fluid.

Scientists can now use the fluid as a model of other, more complicated perfect flows, to estimate the viscosity of the plasma in the early universe, as well as the quantum friction within neutron stars—properties that would otherwise be impossible to calculate. Scientists might even be able to approximately predict the sounds they make.

"Universal sound diffusion in a strongly interacting Fermi gas" Science (2020). science.sciencemag.org/cgi/doi … 1126/science.aaz5756

https://phys.org/news/2020-12-physicists-capture-fluid.html?utm_sou...

**How plants compete for underground real estate affects climate change and food production

You might have observed plants competing for sunlight—the way they stretch upwards and outwards to block each other's access to the sun's rays—but out of sight, another type of competition is happening underground. In the same way that you might change the way you forage for free snacks in the break room when your colleagues are present, plants change their use of underground resources when they're planted alongside other plants.

In a paper published today in Science, an international team of researchers  sheds light on the underground life of plants. Their research used a combination of modeling and a greenhouse experiment to discover whether plants invest differently in root structures when planted alone versus when planted alongside a neighbour.

Plants make two different types of roots: fine roots that absorb water and nutrients from the soil, and coarse transportation roots that transport these substances back to the plant's center. Plant "investment" in roots involves both the total volume of roots produced and the way in which these roots are distributed throughout the soil. A plant could concentrate all of its roots directly beneath its shoots, or it could spread its roots out horizontally to forage in the adjacent soil—which risks competition with the roots of neighboring plants.

The team's model predicted two potential outcomes for root investment when plants find themselves sharing soil. In the first outcome, the neighboring plants "cooperate" by segregating their root systems to reduce overlap, which leads to producing less roots overall than they would if they were solitary. In the second outcome, when a plant senses reduced resources on one side due to the presence of a neighbor, it shortens its root system on that side but invests more in roots directly below its stem.

Natural selection predicts this second scenario, because each plant acts to increase its own fitness, regardless of how those actions impact other individuals. If plants are very close together, this increased investment in root volume, despite segregation of those roots, could result in a tragedy of the commons, whereby the resources (in this case, soil moisture and nutrients) are depleted.

When this was tested on pepper plants, the team discovered that the outcome depends on how close a pair of plants are to each other. If planted very close together, plants will be more likely to heavily invest in their root systems to try to outcompete each other for finite underground resources; if they are planted further apart, they will likely invest less in their root systems than a solitary plant would.

Specifically, they found that when planted near others, pepper plants increased investment in roots locally and reduced how far they stretched their roots horizontally, to reduce overlap with neighbors. There was no evidence for a "tragedy of the commons" scenario, since there was no difference in the total root biomass or relative investment in roots compared to aboveground structures (including the number of seeds produced per plant) for solitary versus co-habiting plants.

 C. Cabal el al., "The exploitative segregation of plant roots," Science (2020). science.sciencemag.org/cgi/doi … 1126/science.aba9877

https://phys.org/news/2020-12-underground-real-estate-affects-clima...

Scientists predict 'optimal' organism stress levels

Scientists have created an evolutionary model to predict how animals should react in stressful situations.

Almost all organisms have fast-acting stress responses, which help them respond to threats—but being stressed uses energy, and chronic stress can be damaging.

The new study—by an international team including the University of Exeter—suggests most animals remain stressed for longer than is optimal after a stress-inducing incident.

The reasons for this are not clear, but one possibility is that there is a limit to how quickly the body can remove stress hormones from circulation.

So scientists have created one of the first mathematical models to understand how organisms have evolved to deal with stressful events. It combines existing research on stress physiology in a variety of organisms with analysis of optimal responses that balance the costs and benefits of stress.

We know stress responses vary hugely between different species and even among individuals of the same species—as we see in humans. This  study is a step towards understanding why stress responses are so variable.

The researchers define stress as the process of an organism responding to "stressors" (threats and challenges in their environment), including both detection and the stress response itself. A key point highlighted in the study is the importance of how predictable threats are.

The model suggests that an animal living in a dangerous environment should have a high "baseline" stress level, while an animal in a safer environment would benefit from being able to raise and reduce stress levels rapidly.

This approach reveals environmental predictability and physiological limits as key factors shaping the evolution of stress responses.

Barbara Taborsky et al, Towards an Evolutionary Theory of Stress Responses, Trends in Ecology & Evolution (2020). DOI: 10.1016/j.tree.2020.09.003

https://phys.org/news/2020-12-scientists-optimal-stress.html?utm_so...

Medicine-carriers made from human cells can cure lung infections

Scientists used human white blood cell membranes to carry two drugs, an antibiotic and an anti-inflammatory, directly to infected lungs in mice.

The nano-sized drug delivery method developed successfully treated both the bacterial growth and inflammation in the mice's lungs. The study, recently published in Communications Biology, shows a potential new strategy for treating infectious diseases, including COVID-19.

If a doctor simply gives two drugs to a patient, they don't go directly to the lungs. They circulate in the whole body, so potentially there's a lot of toxicity. Instead, researchers can load the two types of drugs into these vesicles that specifically target the lung inflammation.

The research team has developed a method to essentially peel the membrane from neutrophils, the most common type of white blood cells that lead the body's immune system response. Once emptied, these membranes can be used as nanovesicles, tiny empty sacks only 100 to 200 nanometers wide, which scientists can then fill with medicine.

These nanovesicles retain some of the properties of the original white blood cells, so when they are injected into a patient, they travel directly to the inflamed area just as the cells would normally, but these nanovesicles carry the medicines that the scientists implanted to attack the infection.

Jin Gao et al, Co-delivery of resolvin D1 and antibiotics with nanovesicles to lungs resolves inflammation and clears bacteria in mice, Communications Biology (2020). DOI: 10.1038/s42003-020-01410-5

https://phys.org/news/2020-12-medicine-carriers-human-cells-lung-in...

Common pipe alloy can form cancer-causing chemical in drinking water

Rusted iron pipes can react with residual disinfectants in drinking water distribution systems to produce carcinogenic hexavalent chromium in drinking water, reports a study by engineers .

Chromium is a metal that occurs naturally in the soil and groundwater. Trace amounts of trivalent chromium eventually appear in the drinking water and food supply and are thought to have neutral effects on health. Chromium is often added to iron to make it more resistant to corrosion.

Certain chemical reactions can change chromium atoms into a hexavalent form that creates cancer-causing genetic mutations in cells.

Cheng Tan et al, Hexavalent Chromium Release in Drinking Water Distribution Systems: New Insights into Zerovalent Chromium in Iron Corrosion Scales, Environmental Science & Technology (2020). DOI: 10.1021/acs.est.0c03922

https://phys.org/news/2020-12-common-pipe-alloy-cancer-causing-chem...

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Engineers invent fast and safe way to store natural gas for useful ...

applications

Natural gas is the cleanest of all fossil fuels, but storing it safely and affordably remains a challenge. Now, engineers from the National University of Singapore (NUS) have devised a method to convert natural gas into a non-explosive solid that can be easily stored and transported. Using a novel, low-toxicity additive mixture they formulated, the conversion can be completed in just 15 minutes—the fastest time so far.

The NUS team worked on a process of converting natural gas into a sold form known as gas hydrates, or combustible ice, which consists of molecules of natural gas trapped in "cages" formed by water molecules. In fact, nature stores natural gas this way, but the process is extremely slow. Other researchers have previously managed to speed it up artificially, but they resorted to using highly toxic additives which are unsafe for both the environment and personnel involved.

The new additive mixture formulated by the NUS researchers contains L-tryptophan, well known as an essential amino acid in people's diet. This muscle-building amino acid can also greatly speed up the caging of natural gas into solid hydrate. The NUS formulation produces the fastest reaction rate to date—more than twice as fast as existing standards—while being less toxic and safer to handle.

Gaurav Bhattacharjee et al. Ultra-rapid uptake and the highly stable storage of methane as combustible ice, Energy & Environmental Science (2020). DOI: 10.1039/D0EE02315A

Climate change is resulting in profound, immediate and worsening health impacts, over 120 researchers say

This year's annual report of The Lancet Countdown on Health and Climate Change, released today, presents the latest data on health impacts from a changing climate.

Among its results, the report found there were 296,000 heat-related premature deaths in people over 65 years in 2018 (a 54% increase in the last two decades), and that global yield potential for major crops declined by 1.8–5.6% between 1981 and 2019.

based on current population data, 145 million people face potential inundation with global mean sea-level rise of one metre. This jumps to 565 million people with a five metre sea-level rise.

Unless urgent action is taken, the health consequences of climate change will worsen. A globally coordinated effort tackling COVID-19 and climate change in unison is vital, and will mean a triple win: better public health, a more sustainable economy and environmental protection.

https://theconversation.com/climate-change-is-resulting-in-profound...

Voyager spacecraft detect new type of solar electron burst

In a new study, a team of physicists led by the University of Iowa report the first detection of bursts of cosmic ray electrons accelerated by shock waves originating from major eruptions on the sun. The detection, made by instruments onboard both the Voyager 1 and Voyager 2 spacecraft, occurred as the Voyagers continue their journey outward through interstellar space, thus making them the first craft to record this unique physics in the realm between stars.

These newly detected electron bursts are like an advanced guard accelerated along magnetic field lines in the interstellar medium; the electrons travel at nearly the speed of light, some 670 times faster than the shock waves that initially propelled them. The bursts were followed by plasma wave oscillations caused by lower-energy electrons arriving at the Voyagers' instruments days later—and finally, in some cases, the shock wave itself as long as a month after that.

The shock waves emanated from coronal mass ejections, expulsions of hot gas and energy that move outward from the sun at about one million miles per hour. Even at those speeds, it takes more than a year for the shock waves to reach the Voyager spacecraft, which have traveled further from the sun (more than 14 billion miles and counting) than any human-made object.

Astronomical Journal (2020). DOI: 10.3847/1538-3881/abc337

https://phys.org/news/2020-12-voyager-spacecraft-solar-electron.htm...

Lab-Grown Chicken Meat Is Finally Going on Sale in a World First

Lab-grown chicken will soon be available in restaurants in Singapore after the country became the first to green-light meat created without slaughtering any animals.

Consumption of regular meat is an environmental threat as cattle produce methane, a potent greenhouse gas, while logging forests to make way for animals destroys natural barriers against climate change.

Demand for sustainable meat alternatives is rising due to growing pressure from consumers about the environment and animal welfare, but other products in the market are plant-based.

There were concerns that lab-grown varieties would be too expensive, but a spokesman for Eat Just said the company had made "considerable progress" in lowering the cost.

https://www.sciencealert.com/singapore-will-be-the-first-country-to...

Anti-gravity: How a boat can float upside down

Here on Earth, everything is subject to gravity—it makes objects fall to the ground and rivers flow from higher ground to the sea. We know what would happen without it, thanks to images of astronauts floating around their spaceship. But could we design an anti-gravity machine, something that would make objects fall upwards, oceans levitate, and boats float upside down?

Boats floating at the interfaces of the levitating liquid layer.

Inverted pendulum with a vertically oscillated pivot.

Creation of a levitating liquid layers

Vision-restoring brain implants spell breakthrough

Scientists are a step closer to restoring vision for the blind, after building an implant that bypasses the eyes and allows monkeys to perceive artificially induced patterns in their brains. The technology, developed by a team at the Netherlands Institute for Neuroscience (NIN), was described in the journal Science on Thursday. It builds on an idea first conceived decades ago: electrically stimulating the brain so it "sees" lighted dots known as phosphenes, which can also be thought of as artificial pixels. But the concept had never realized its full potential because of technical limitations. A team led by NIN director Pieter Roelfsema developed implants consisting of 1024 electrodes wired into the visual cortex of two sighted monkeys, resulting in a much higher resolution than has previously been achieved. The visual cortex is located at the back of the brain and many of its features are common to humans and other primates. 

The NIN team profited from advances in miniaturization, and also devised a system to make sure their input currents were big enough to create noticeable dots, but not so great that the pixels grew too large.

They achieved this by placing some electrodes at a more advanced stage of the visual cortex, to monitor how much signal was coming through and then adjust the input.

https://science.sciencemag.org/content/370/6521/1168

https://researchnews.cc/news/3931/Vision-restoring-brain-implants-s...

Graphic on how scientists are developing techniques they hope will one day help restore sight to people with damaged eyes, by sending electronic signals directly to the brain. AFP.

Self-repairing gelatin-based film could be a smart move for electro...

Dropping a cell phone can sometimes cause superficial cracks to appear. But other times, the device can stop working altogether because fractures develop in the material that stores data. Now, researchers reporting in ACS Applied Polymer Materials have made an environmentally friendly, gelatin-based film that can repair itself multiple times and still maintain the electronic signals needed to access a devices data. The material could be used someday in smart electronics and health-monitoring devices.

https://www.acs.org/content/acs/en/pressroom/presspacs/2020/acs-pre...

Scientists Confirm Certain Spider Bites Inject Something Even Worse Than Venom: dreadful bacteria

A tiny brown invasive species of spider that's creeping its way across the UK has a dangerous reputation for dissolving flesh.

There's now compelling evidence suggesting that stories of the false widow spider (Steatoda nobilis) causing horrid skin infections has at least some basis in fact.

In most cases, the worst you might expect from a false widow spider bite is a few hours of pain around the injection site, and maybe a day or two of stiff joints. No worse than a wasp sting, really.

It's not the venom we need to be concerned about though – it's the risk posed by bacteria found on its fangs.

Every now and then a story will hit UK headlines of an arachnid bite leaving victims with something far worse than a throbbing finger. Swollen hands, rotting holes of pus, threats of amputation, or even deaths have provided ample nightmare fuel.

Though formal identification isn't always possible, the false widow typically cops the blame regardless.

Experts have understandably come to the spider's defence, arguing that even if it is guilty of leaving a couple of holes, it's the victim who supplies the necrotising bacteria by scratching at the site with dirty fingernails.

Hard evidence in support of either explanation has been scarce. So Dunbar's team collected specimens of false widows along with some lace-webbed (Amaurobius similis) and giant house spiders (Eratigena atrica) from gardens and pathways, and took them back to the lab.

There the arachnids had their bodies and chelicerae (appendages by their mouth parts) swabbed for bacteria, and venom collected from the false widows.

The study demonstrates that spiders are not just venomous but are also carriers of dangerous bacteria capable of producing severe infections. The biggest threat is that some of these bacteria are multi-drug resistant, making them particularly difficult to treat with regular medicine

https://www.nature.com/articles/s41598-020-77839-9

https://www.sciencealert.com/scientists-confirm-spider-s-bite-injec...

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3 kinds of bias that shape your perception of science

China turns on nuclear-powered 'artificial sun' (Update)

China successfully powered up its "artificial sun" nuclear fusion reactor for the first time, state media reported Friday, marking a great advance in the country's nuclear power research capabilities.

The HL-2M Tokamak reactor is China's largest and most advanced nuclear fusion experimental research device, and scientists hope that the device can potentially unlock a powerful clean energy source.

It uses a powerful magnetic field to fuse hot plasma and can reach temperatures of over 150 million degrees Celsius, according to the People's Daily—approximately ten times hotter than the core of the sun.

Located in southwestern Sichuan province and completed late last year, the reactor is often called an "artificial sun" on account of the enormous heat and power it produces.

https://phys.org/news/2020-12-china-nuclear-powered-artificial-sun....

Research reveals how airflow inside a car may affect COVID-19 transmission risk

A new study of airflow patterns inside a car's passenger cabin offers some suggestions for potentially reducing the risk of COVID-19 transmission while sharing rides with others.

The study used computer models to simulate the airflow inside a compact car with various combinations of windows open or closed. The simulations showed that opening windows—the more windows the better—created airflow patterns that dramatically reduced the concentration of airborne particles exchanged between a driver and a single passenger. Blasting the car's ventilation system didn't circulate air nearly as well as a few open windows, the researchers found.

Driving around with the windows up and the air conditioning or heat on is definitely the worst scenario, according to the computer simulations by this team.

The best scenario they found was having all four windows open, but even having one or two open was far better than having them all closed.

The researchers stress that there's no way to eliminate risk completely—and, of course, current guidance from the U.S. Centers for Disease Control (CDC) notes that postponing travel and staying home is the best way to protect personal and community health. The goal of the study was simply to study how changes in airflow inside a car may worsen or reduce risk of pathogen transmission.

Varghese Mathai et al, Airflows inside passenger cars and implications for airborne disease transmission, Science Advances (2020). DOI: 10.1126/sciadv.abe0166

https://phys.org/news/2020-12-car-pandemic-windows.html?utm_source=...

Reviving puppetry for science, technology communication

https://www.freepressjournal.in/bhopal/madhya-pradesh-reviving-pupp...

The first observation of three massive gauge bosons produced in proton-proton collisions

The Standard Model, the most exhaustive existing theory outlining fundamental particle interactions, predicts the existence of what are known as triboson interactions. These interactions are processes in which three-gauge bosons are simultaneously produced from one Large Hadron Collider event.

Triboson interactions are incredibly rare, often up to hundreds of times rarer than Higgs boson events, as they typically take place once every 100 billion proton-proton collisions. Although the Standard Model predicts their existence, physicists had so far been unable to observe them experimentally.

The CMS Collaboration, a large group of researchers from numerous physics institutes worldwide have recently observed the production of three massive gauge bosons in proton-proton collisions for the first time ever. Their paper, published in Physical Review Letters, offers the first experimental evidence of the existence of triboson interactions, opening up new possibilities for the study the interactions between fundamental massive gauge bosons, namely the W±, Z, and Higgs boson.

Observation of the production of three massive gauge bosons at √s=13  TeV. Physical Review Letters(2020). DOI: 10.1103/PhysRevLett.125.151802.

https://phys.org/news/2020-12-triple-threat-massive-gauge-bosons.ht...

Scientists Discover an Unexpected Structure Hidden Inside Plant Cells

A team of researchers has just published a paper describing a surprising structure existing within an organelle – one that has remained hidden in plain sight for decades.

The organelle is called a peroxisome – a bubble-like single membrane filled with a granular protein matrix called a lumen. They aren't the most important cell machinery (not exactly a mitochondria or nucleus) but these very, very tiny cell organs have key roles in breaking down and synthesising molecules. Inside the peroxisomes of plant cells, researchers were surprised to find vesicles – something we didn't think the organelles had. Peroxisomes float around the cells of all multicellular organisms removing reactive molecules containing oxygen and helping break down fats. In humans and other mammals, they're only 0.1 micrometres – small enough that even with high power microscopes, there's not much to see. "Peroxisomes in yeast and mammalian cells are smaller than the resolution of light.

With fluorescence microscopy, you could only ever see a dot. That's just the limit that light can do.

https://www.nature.com/articles/s41467-020-20099-y

https://www.sciencealert.com/scientists-discover-surprise-structure...

**Elementary particles part ways with their properties

Yakir Aharonov and Daniel Rohrlich What is nonlocal in counterfactual quantum communication?, Physical Review Letters, Accepted Manuscript. journals.aps.org/prl/accepted/ … bc9200223328b0ab042b

Arxiv: arxiv.org/abs/2011.11667

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**Research: Millions of smart devices vulnerable to hacking

https://techxplore.com/news/2020-12-millions-smart-devices-vulnerab...

Using targeted microbubbles to administer toxic cancer drugs

New research has shown how microbubbles carrying powerful cancer drugs can be guided to the site of a tumour using antibodies.

Microbubbles are small manufactured spheres half the size of a red blood cell—and scientists think they can be used to transport drugs to highly specific locations within the body.

Scientists have targeted microbubbles through the use of a 'navigational aid' - antibodies attracted to the growth hormone found in high levels in the blood vessels supplying a tumour.

The antibodies were attached to the microbubbles—and as a result of being attracted to the growth hormone, the microbubbles became concentrated at the site of the tumour. A pulse from an ultrasound device was used to burst open the microbubbles, and that released the anti-cancer agent.

One of the big problems with cancer drugs is that they are highly toxic to the rest of the body too. Microbubble technology allows us to use these very powerful drugs with precision and that reduces the risk of the drug damaging healthy cells nearby.

This work is about finely focused drug delivery. The animal-based study also revealed that by attaching the drug directly to the microbubbles allowed it to circulate in the body for longer, increasing delivery into the tumour—in effect making the drug more potent. As a result, the scientists were able to slow cancer growth with a much smaller drug dose.

Nicola Ingram et al, Ultrasound-triggered therapeutic microbubbles enhance the efficacy of cytotoxic drugs by increasing circulation and tumor drug accumulation and limiting bioavailability and toxicity in normal .tissues, Theranostics (2020). DOI: 10.7150/thno.49670

https://phys.org/news/2020-12-microbubbles-toxic-cancer-drugs.html?...

It's Not Just Humans. Sparrows Have Been Seen Using Preventative Medicine

 we might not be the only species that knows certain things in nature can help treat our ills.

A new correspondence paper has put forward the idea that russet sparrows (Passer cinnamomeus) in China are using wormwood (Artemisia verlotorum) leaves in their nest as a preventative medicine, to reduce parasites and help their babies get bigger.

The conclusion that animals can use medicinal plants to their benefit is not necessarily new
 Pregnant elephants in Kenya eat a particular leaf to induce birth, while many other mammals use medicinal plants to self-medicate – sometimes to prevent disease or just generally feel better from an ailment.

But it's still pretty amazing that a tiny sparrow might know that some plants are more important than others for protecting against disease.

"In China, russet sparrows incorporate wormwood leaves into their nests around the same time that local people hang wormwood from their doors as a traditional custom during the Dragon Boat Festival

The belief that this behaviour confers protection against ill health is supported by the description of anti-parasite compounds in wormwood. It has been suggested that the incorporation of fresh wormwood leaves into nests may serve a similar function for sparrows. the birds actively seek out nest locations close to the available wormwood and resupply established nests with fresh wormwood leaves gathered based solely on the leaves smell.

The nests containing wormwood leaves had lower parasite loads. By decreasing the number of parasites such as mites, the sparrows that add more wormwood leaves to their nest produce heavier and healthier chicks.

Sparrows use a medicinal herb to defend against parasites and increase offspring condition

https://www.cell.com/current-biology/fulltext/S0960-9822(20)31525-6

https://www.sciencealert.com/sparrows-have-been-seen-using-preventa...

Space weather discovery puts 'habitable planets' at risk

A discovery that links stellar flares with radio-burst signatures will make it easier for astronomers to detect space weather around nearby stars outside the Solar System. Unfortunately, the first weather reports from our nearest neighbour, Proxima Centauri, are not promising for finding life as we know it.

Astronomers have recently found there are two 'Earth-like' rocky planets around Proxima Centauri, one within the 'habitable zone' where any water could be in liquid form. 

Proxima Centauri is just 4.2 light years from Earth.

But given Proxima Centauri is a cool, small red-dwarf star, it means this habitable zone is very close to the star; much closer in than Mercury is to our Sun.

Some present research shows is that this makes the planets very vulnerable to dangerous ionising radiation that could effectively sterilise the planets. astronomers have for the first time shown a definitive link between optical flares and radio bursts on a star that is not the Sun. The finding, published today in The Astrophysical Journal, is an important step to using radio signals from distant stars to effectively produce space weather reports.

 Astrophysical Journal (2020). DOI: 10.3847/1538-4357/abca90

https://phys.org/news/2020-12-space-weather-discovery-habitable-pla...

Manmade mass now outweighs life on Earth: study

For the first time in history manmade materials now likely outweigh all life on Earth, scientists said recently in research detailing the "crossover point" at which humanity's footprint is heavier than that of the natural world.

The weight of roads, buildings and other constructed or manufactured materials is doubling roughly every 20 years, and authors of the research said it currently weighed 1.1 teratonnes (1.1 trillion tonnes).

As mankind has ramped up its insatiable consumption of natural resources, the weight of living biomass—trees, plants and animals—has halved since the agricultural revolution to stand at just 1 teratonne currently, the study found.

Estimating changes in global biomass and manmade mass since 1990, the research showed that the mass of human-produced objects stood at just three percent of the weight of biomass at the start of the 20th century.

But since the post-World War II global production boom, manufacturing has surged to the extent that humans now produce the equivalent of the weight of every person on Earth every week on average.

Global human-made mass exceeds all living biomass, Nature (2020). DOI: 10.1038/s41586-020-3010-5 , www.nature.com/articles/s41586-020-3010-5

https://phys.org/news/2020-12-manmade-mass-outweighs-life-earth.htm...

Why did Mount Everest's height change?

The world's highest mountain is now officially a little higher. China and Nepal presented a new official figure of 8,848.86 meters (29,031.69 feet) above sea level. 

China and Nepal agreed this week on a new standard height for Mount Everest. Geological changes, the complicated business of measuring a mountain and varying criteria for determining the world's highest peak will likely ensure the question isn't settled for good.

The mountain's height changes. The movement of tectonic plates can lift it up ever so gradually, while earthquakes can bring it down.

The countervailing forces may help maintain a degree of stability over time.

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There's more than one way to measure a mountain.

Last year, a Nepalese team set up a satellite navigation marker on Everest's peak to gauge its exact position via GPS satellites. A Chinese team undertook a similar mission this spring, though it used the Chinese-made Beidou constellation of navigation satellites, along with other equipment.

At the same time, Nepalese crews took measurements with modern, laser-equipped versions of instruments called theodolites, first used to gauge the mountain's height in 1856 by measuring angles using trigonometry.

The Nepalese team also used ground penetrating radar to measure the amount of snow and ice that sits on top of its highest rock.

The new height is 0.86 meters (more than 2 feet) above the higher of the countries' two previous figures, that given by Nepal. The two had diverged for year over the mountain's actual height.

Measuring the height above sea level has always been tricky because ocean levels vary considerably depending on tides, magnetism and other factors. Rising sea levels are creating another factor for future measurements.

How high above sea level is just one way of measuring a mountain's height. One reason Everest wins the prize is that its base sits high up on already lofty foothills.

As measured from the Earth's core, Ecuador's Mount Chimborazo is the world's highest, standing more than 2,072 meters (6,800 feet) above Everest. Because the Earth bulges in the middle, mountains along the equator are farther from the core.

Measuring from the foot of the mountain to the peak, Hawaii's Mauna Kea is the tallest. Most of it, however, is under the sea.

https://phys.org/news/2020-12-mount-everest-height.html?utm_source=...

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Pesticides in contact with plastic mulch take longer to degrade

The use of plastic mulch (plastic covering on crop lines) is a widespread technique used in agricultural regions in order to increase the profitability of the crops. According to the European Commission, 100,000 tons of plastic mulch was used per year in the European Union in 2016. Taking these figures into account and the fact that after the harvest some plastic usually remains in the soil, the accumulation of plastic in territories of intensive agriculture is an environmental problem that is of concern in the sector and also for public administration.

Scientists discover how COVID-19 virus causes multiple organ failure in mice

 Researchers  created a version of COVID-19 in mice that shows how the disease damages organs other than the lungs. Using their model, the scientists discovered that the SARS-CoV-2 virus can shut down energy production in cells of the heart, kidneys, spleen and other organs.

Understanding how this virus can hijack our cells might eventually lead to new ways to prevent or treat the organ failure that can accompany COVID-19 in humans. 

Research in humans has suggested that SARS-CoV-2 can circulate through the bloodstream to reach multiple organs. So in the UCLA experiment, the researchers first engineered mice to have the human version of ACE2 in the heart and other vital organs. Then, they infected half of the animals by injecting SARS-CoV-2 into their bloodstreams. Over the following days, the researchers tracked the animals’ overall health and analyzed how levels of certain genes and proteins in their bodies changed.

Within seven days, all of the mice with COVID-19 had stopped eating and were completely inactive, and had lost, on average, about 20% of their body weight. Animals that had been engineered to carry the human ACE2 protein but had not been infected with the virus, on the other hand, did not lose a significant amount of weight.

Moreover, the COVID-19 infected animals had altered levels of immune cells, swelling of the heart tissue and wasting away of the spleen — all symptoms that have been observed in people who are critically ill with COVID-19.

The research team also looked at which genes were turned on and off in the mice infected with SARS-CoV-2, and they discovered other signs of disease. Common molecular processes that help cells generate energy — through mechanisms known as the tricarboxylic acid cycle, or TCA cycle, and electron transport chain — were shut off in the heart, kidney, spleen and lungs.

If a virus snuffs out the energy-generating pathways in multiple organs of the body, that’s going to really wreak havoc.

The study also revealed that some changes were long-lasting throughout the organs in mice with COVID-19. In addition to temporarily altering which genes were turned on and off in some cells, the virus made epigenetic changes — chemical alterations to the structure of DNA that cause more lasting effects. This could explain why, in some people with COVID-19, symptoms persist for weeks or months after their bodies are rid of the virus.

https://newsroom.ucla.edu/releases/covid-19-multiple-organ-failure-...

https://researchnews.cc/news/4027/Scientists-discover-how-COVID-19-...

These simple steps can help prevent heat-related fatalities

Dogs Probably Don't Understand Us as Well as We Think, Brain Scans Reveal

Dogs may never learn that every sound of a word matters

https://www.sciencealert.com/dogs-may-not-actually-understand-us-as...

This Teen's Brilliantly Simple Explainer on Quantum Mechanics Just Won a Global Prize

Blocking protein restores strength, endurance in old mice, study finds

Muscle loss during aging is known as sarcopenia, and it accounts for billions of dollars of health care expenditures  each year as people lose the ability to care for themselves, experience more falls and become increasingly less mobile. It is due to changes in muscle structure and function: The muscle fibers shrink and the number and function of the cellular powerhouses known as mitochondria dwindle.

Blocking the activity of a single protein in old mice for one month restores mass and strength to the animals' withered muscles and helps them run longer on a treadmill, according to a study by researchers. Conversely, increasing the expression of the protein in young mice causes their muscles to atrophy and weaken.

The improvement is really quite dramatic. The old mice are about 15% to 20% stronger after one month of treatment, and their muscle fibres look like young muscle. Considering that humans lose about 10% of muscle strength per decade after about age 50, this is quite remarkable.

The protein hasn't previously been implicated in aging. The researchers show that the amount of the protein, called 15-PGDH, is elevated in old muscle and is widely expressed in other old tissues. Experiments they conducted in human tissue raise hopes for a future treatment for the muscle weakness that occurs as people age.

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Prostaglandin E2 levels are regulated by 15-PGDH, which breaks down prostaglandin E2. The researchers used a highly sensitive version of mass spectrometry, a method for differentiating closely related molecules, to determine that compared with young mice, the 15-PGDH levels are elevated in the muscles of older animals, and the levels of prostaglandin E2 are lower.

They found a similar pattern of 15-PGDH expression in human muscle tissues, as those from people in their 70s and early 80s expressed higher levels than those from people in their mid-20s.

"We knew from our previous work that prostaglandin E2 was beneficial for regeneration of young muscles.

"Inhibition of prostaglandin-degrading enzyme 15-PGDH rejuvenates aged muscle mass and strength" Science (2020). science.sciencemag.org/lookup/ … 1126/science.abc8059

https://medicalxpress.com/news/2020-12-blocking-protein-strength-mi...

Researchers identify the physical mechanism that can kill bacteria with gold nanoparticles

Finding alternatives to antibiotics is one of the biggest challenges facing the research community. Bacteria are increasingly resistant to these drugs, and this resistance leads to the deaths of more than 25,000 around the world. Now, a multidisciplinary team of researchers have discovered that the mechanical deformation of bacteria is a toxic mechanism that can kill bacteria with gold nanoparticles. The results of this research have been published in the journal Advanced Materials and are a breakthrough in researchers' understanding the antibacterial effects of nanoparticles and their efforts to find new materials with bactericide properties.

Since the times of Ancient Egypt, gold has been used in a range of medical applications and, more recently, as for diagnosing and treating diseases such as cancer. This is due to the fact that gold is a chemically inert material, that is, it does not react or change when it comes into contact with an organism. Amongst the scientific community, nanoparticles are known for their ability to make tumors visible and for their applications in nanomedicine.

This new research shows that these chemically inert nanoparticles can kill bacteria thanks to a physical mechanism that deforms the cell wall. To demonstrate this, the researchers have synthesized in the laboratory gold nanoparticles in the shape of an almost perfect sphere and others in the shape of stars, all measuring 100 nanometres (8 times thinner than a hair). The group analyzed how these particle interact with living bacteria. Researchers found that the bacteria become deformed and deflate like a ball that is having the air let out before dying in the presence of these nanoparticles as if the cell wall had spontaneously exploded. 

The scientists thought that a physical mechanism might be responsible for the death of the bacteria. Consequently, they carried out aa numerical simulations to analyze how a homogenous layer of individual nanoparticles could apply sufficient mechanical tension to the cell wall of the bacteria that it ends up breaking seemingly by stretching, like a balloon that is inflated from different points until it exploded.

To confirm this hypothesis, the researchers created an artificial model of a bacterial cell membrane to evaluate its response when it entered into contact with the 100 nm gold nanoparticles. They found that the model spontaneously contracted until it completely collapsed, thus proving the hypothesis that nanoparticles apply a mechanical stretch on the cell membrane of the bacteria.

Denver P. Linklater et al, Antibacterial Action of Nanoparticles by Lethal Stretching of Bacterial Cell Membranes, Advanced Materials (2020). DOI: 10.1002/adma.202005679

https://phys.org/news/2020-12-physical-mechanism-bacteria-gold-nano...

** The greening of the Earth is approaching its limit

When plants absorb this gas to grow, they remove it from the atmosphere and it is sequestered in their branches, trunk or roots. An article published today in Science shows that this fertilizing effect of CO2 is decreasing worldwide, according to the text co-directed by Professor Josep Peñuelas of the CSIC at CREAF and Professor Yongguan Zhang of the University of Nanjin, with the participation of CREAF researchers Jordi Sardans and Marcos Fernández. The study, carried out by an international team, concludes that the reduction has reached 50% progressively since 1982 due basically to two key factors: the availability of water and nutrients.

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COVID-19 and other pandemics are the effects of our negative impact...

There is increasing awareness that the COVID-19 pandemic is the consequence of environmental and societal crises. A new paper just published in the scientific journal Science of the Total Environment by international research fellows of the Konrad Lorenz Institute for Evolution and Cognition Research (KLI), an Austrian independent center for advanced studies in the life and sustainability sciences, presents an interdisciplinary approach to analyze the COVID-19 pandemic as a phenomenon affecting the diversity of all spheres of the total environment.

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Bad news for fake news: New research helps combat social media misi...

Rice University researchers have discovered a more efficient way for social media companies to keep misinformation from spreading online using probabilistic filters trained with artificial intelligence.

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Researchers shed new light on mysteries behind the light emission o...

A team of researchers from the NYU Abu Dhabi's (NYUAD) Smart Materials Lab (SML) led by Professor of Chemistry Panče Naumov has conducted a thorough review of the scientific literature surrounding the natural production of light, called bioluminescence, and developed conclusions that will help others in the field direct their research to uncover the mysteries behind this fascinating natural phenomenon.

Distinct Microbiome and Metabolites Linked with Depression

Since its completion in November 1963, the Telescope had been used for radar astronomy and radio astronomy, and had been part of the Search for extraterrestrial intelligence (SETI) program. It was also used by NASA for Near-Earth object detection.
Arecibo joins with telescopes in Europe and with the Russian Radio Astron satellite to form the largest telescope ever – 20 times the size of the Earth. Arecibo continues to obtain orbit refinement of potentially hazardous near-Earth asteroids (PHAs) to identify possible future Earth impactors.
It has several acheivements since it started working
http://www.naic.edu/about/accomplishments.html#:~:text=Arecibo%20jo....

Scientists build whole functioning thymus from human cells

Researchers at the Francis Crick Institute and University College London have rebuilt a human thymus, an essential organ in the immune system, using human stem cells and a bioengineered scaffold. Their work is an important step towards being able to build artificial thymi which could be used as transplants.

The thymus is an organ in the chest where T lymphocytes, which play a vital role in the immune system, mature. If the thymus does not work properly or does not form during foetal development in the womb, this can lead to diseases such as severe immunodeficiency, where the body cannot fight infectious diseases or cancerous cells, or autoimmunity, where the immune system mistakenly attacks the patient's own healthy tissue.

In their proof-of-concept study, published in Nature Communications today, the scientists rebuilt thymi using stem cells taken from patients who had to have the organ removed during surgery. When transplanted into mice, the bioengineered thymi were able to support the development of mature and functional human T lymphocytes.

While researchers have previously rebuilt other organs or sections of organs, this is the first-time scientists have successfully rebuilt a whole working human thymus. 

Campinoti, S et al. (2020). Reconstitution of a functional human thymus by postnatal stromal progenitor cells and natural whole-organ scaffolds. Nature Communications, DOI: 10.1038/s41467-020-20082-7

https://medicalxpress.com/news/2020-12-scientists-functioning-thymu...

Some droughts during the Indian monsoon are due to unique North Atl...

A team of researchers from the Indian Institute of Science and Cotton University has found that some droughts during monsoon season in India are due to unique North Atlantic disturbances. In their paper published in the journal Science, the group describes their study of weather patterns in South Asia over the past century and what it showed about monsoon season droughts.

P. J. Borah et al. Indian monsoon derailed by a North Atlantic wavetrain, Science (2020). DOI: 10.1126/science.aay6043

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Current pace of action on climate change is "unthinkable" state ex ...

Justifiable pride can be taken in the incremental accomplishments of international climate change cooperation, but it is "unthinkable" to continue at the current pace. The global response to climate change is completely insufficient and leaves the world on a "road to hell".

Climate Policy (2020). DOI: 10.1080/14693062.2020.1860567

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Black holes gain new powers when they spin fast enough

General relativity is a profoundly complex mathematical theory, but its description of black holes is amazingly simple. A stable black hole can be described by just three properties: its mass, its electric charge and its rotation or spin. Since black holes aren't likely to have much charge, it really takes just two properties. If you know a black hole's mass and spin, you know all there is to know about the black hole.

This property is often summarized as the no-hair theorem. Specifically, the theorem asserts that once matter falls into a black hole, the only characteristic that remains is mass. You could make a black hole out of a sun's worth of hydrogen, chairs or those old copies of National Geographic from Grandma's attic, and there would be no difference. Mass is mass as far as general relativity is concerned. In every case, the event horizon of a black hole is perfectly smooth, with no extra features. "The balck holes have no hair."

But with all its predictive power, general relativity has a problem with quantum theory. This is particularly true with black holes. If the no-hair theorem is correct, the information within an object is destroyed when it crosses the event horizon. Quantum theory says that information can never be destroyed. So the valid theory of gravity is contradicted by the valid theory of the quanta. This leads to problems such as the firewall paradox, which can't decide whether an event horizon should be hot or cold.

Several theories have been proposed to solve this contradiction, often involving extensions to relativity. The difference between standard relativity and these modified theories can only be seen in extreme situations, making them difficult to study observationally. But a new paper in Physical Review Letters shows how they might be studied through the spin of a black hole.

Many modified relativity theories have an extra parameter not seen in the standard theory. Known as a massless scalar field, it allows Einstein's model to connect with quantum theory  in a way that isn't contradictory. In this new work, the team looked at how such a scalar field connects to the rotation of a black hole. They found that at low spins, a modified black hole is indistinguishable from the standard model, but at high rotations, the scalar field allows a black hole to have extra features. In other words, in these alternative models, rapidly rotating black holes can have hair.

The hairy aspects of rotating black holes would only be seen near the event horizon itself, but they would also affect merging black holes. As the authors point out, future gravitational wave observatories should be able to use rapidly rotating black holes to determine whether an alternative to general relativity is valid.

Einstein's theory of general relativity has passed every observational challenge so far, but it will likely break down in the most extreme environments of the universe. Studies such as this show how we might be able to discover the theory that comes next.

 Alexandru Dima et al. Spin-Induced Black Hole Spontaneous Scalarization, Physical Review Letters (2020). DOI: 10.1103/PhysRevLett.125.231101

https://phys.org/news/2020-12-black-holes-gain-powers-fast.html?utm...

How epigenetic switches control gene expression

Scientists at Tokyo Institute of Technology have deciphered how to quantitatively assess the effects of specific epigenetic changes on the rate of transcription by developing a mathematical model. Using their method, they successfully generated reconstituted chromatin-bearing histone modifications in vitro. Their study published in Nucleic Acids Research provides an accurate quantitative approach for understanding how site-specific changes to histone proteins impact the accessibility of chromatin and gene expression levels.

Masatoshi Wakamori et al, Quantification of the effect of site-specific histone acetylation on chromatin transcription rate, Nucleic Acids Research (2020). DOI: 10.1093/nar/gkaa1050

https://phys.org/news/2020-12-epigenetic-gene.html?utm_source=nwlet...

Researchers find why 'lab-made' proteins have unusually high temperature stability

Bioengineers have found why proteins that are designed from scratch tend to be more tolerant to high temperatures than proteins found in nature.

Rie Koga et al, Robust folding of a de novo designed ideal protein even with most of the core mutated to valine, Proceedings of the National Academy of Sciences (2020). DOI: 10.1073/pnas.2002120117

https://phys.org/news/2020-12-lab-made-proteins-unusually-high-temp...

Study sheds light on diabetes and COVID interaction
NASHVILLE, TN.- COVID-19 has been linked to cases of new-onset diabetes, diabetes-related emergencies and a higher death rate among diabetes patients. While this suggests that SARS-CoV-2, the virus that causes COVID-19, may infect and damage the insulin-producing beta cells of the pancreas, that does not appear to be the case, according to a report by researchers at Vanderbilt University Medical Center published Dec. 1 in the journal Cell Metabolism. “This is important information in terms of understanding the interaction of diabetes and SARS-CoV-2 and COVID-19,” said Katie Coate, PhD, who led the study with Jeeyeon Cha, MD, PhD. “There are other potential pathways for how SARS-CoV-2 infects cells, and these are just beginning to be described or are as yet undiscovered

Charles Darwin was right about why insects are losing the ability to fly

Most insects can fly.

Yet scores of species have lost that extraordinary ability, particularly on islands.

On the small islands that lie halfway between Antarctica and continents like Australia, almost all the insects have done so.

Flies walk, moths crawl.

Of course, Charles Darwin knew about this wing loss habit of island insects. He and the famous botanist Joseph Hooker had a substantial argument about why this happens. Darwin's position was deceptively simple. If you fly, you get blown out to sea. Those left on land to produce the next generation are those most reluctant to fly, and eventually evolution does the rest. 

But since Hooker expressed his doubt, many other scientists have too.

In short, they have simply said Darwin got it wrong.

Yet almost all of these discussions have ignored the place that is the epitome of flight loss—those 'sub-Antarctic' islands. Lying in the 'roaring forties' and 'furious fifties', they're some of the windiest places on Earth.

If Darwin really got it wrong, then wind would not in any way explain why so many insects have lost their ability to fly on these islands.

Using a large, new dataset on insects from sub-Antarctic and Arctic islands, Monash University researchers examined every idea proposed to account for flight loss in insects, including Darwin's wind idea.

Reporting today in Proceedings of the Royal Society B, they show that Darwin was right for this 'most windy of places'. None of the usual ideas (such as those proposed by Hooker) explain the extent of flight loss in sub-Antarctic insects, but Darwin's idea does. Although in a slightly varied form, in keeping with modern ideas on how flight loss actually evolves.

Windy conditions make insect flight more difficult and energetically costly. Thus, insects stop investing in flight and its expensive underlying machinery (wings, wing muscles) and redirect the resources to reproduction.

Wind plays a major but not exclusive role in the prevalence of insect flight loss on remote islands.

 Proceedings of the Royal Society B, rspb.royalsocietypublishing.or … .1098/rspb.2020.2121

https://phys.org/news/2020-12-charles-darwin-insects-ability.html?u...

Expandable Foam Supersizes 3D-Printed Objects - Headline Science

Physicists create time-reversed optical waves

Optics researchers  have developed a new technique to demonstrate the time reversal of optical waves, which could transform the fields of advanced biomedical imaging and telecommunications.

Time reversal of waves in physics doesn't mean traveling back to the future; it describes a special type of wave which can retrace a path backwards through an object, as if watching a movie of the traveling wave, played in reverse.

UQ's Dr. Mickael Mounaix and Dr. Joel Carpenter, together with Dr. Nick Fontaine's team at Nokia Bell Labs, are the first to demonstrate this time reversal of optical waves, using a new device they developed that allows full 3-D control of light through an optical fiber.

Time reversed optical waves by arbitrary vector spatiotemporal field generation 

https://phys.org/news/2020-12-physicists-time-reversed-optical.html...

** Toward imperceptible electronics that you cannot see or feel

Transparent electronics—such as head-up displays that allow pilots to read flight data while keeping their eyes ahead of them—improve safety and allow users to access data while in transit. For healthcare applications, the electronics need to not only be cheap and straightforward to fabricate, but also sufficiently flexible to conform to skin. Silver nanowire networks meet these criteria. However, current methods of development create random nanowire alignment that's insufficient for advanced applications.

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Nanoparticles, from hype to actual clinical product

Ph.D. candidate Jaleesa Bresseleers, of the TU/e department of Biomedical Engineering, investigated a robust and scalable manufacturing process for nanocarriers and their building blocks. With these insights, the road to widely available clinical applications for nanocarriers has become much shorter.

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The moon controls the release of methane in Arctic Ocean

It may not be very well known, but the Arctic Ocean leaks enormous amounts of the potent greenhouse gas methane. These leaks have been ongoing for thousands of years but could be intensified by a future warmer ocean. The potential for this gas to escape the ocean, and contribute to the greenhouse gas budget in the atmosphere, is an important mystery that scientists are trying to solve.

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A young but completely evolved entirely self-made galaxy

So young and already so evolved: Thanks to observations obtained at the Large Binocular Telescope, an international team of researchers coordinated by Paolo Saracco of the Istituto Nazionale di Astrofisica (INAF, Italy) was able to reconstruct the wild evolutionary history of an extremely massive galaxy that existed 12 billion years ago, when the universe was only 1.8 billion years old, less than 13% of its present age. This galaxy, dubbed C1-23152, formed in only 500 million years, an incredibly short time to give rise to a mass of about 200 billion suns. To do so, it produced as many as 450 stars per year, more than one per day, a star formation rate almost 300 times higher than the current rate in the Milky Way. The information obtained from this study will be fundamental for galaxy formation models for objects it for which it is currently difficult to account.