Why the vast supergalactic plane is teeming with only one type of galaxy

Our own Milky Way galaxy is part of a much larger formation, the local Supercluster structure, which contains several massive galaxy clusters and thousands of individual galaxies. Due to its pancake-like shape, which measures almost a billion light years across, it is also referred to as the Supergalactic Plane.

Most galaxies in the universe fall into one of two categories: firstly, elliptical galaxies, made mostly of old stars and containing typically extremely massive central black holes, and secondly actively star-forming disk galaxies, with a spiral-like structure similar to the Milky Way's. Both types of galaxies are also found in the Local Supercluster, but while the Supergalactic Plane is teeming with bright ellipticals, bright disk galaxies are conspicuously absent.

A cosmic anomaly challenges the standard model of cosmology

This peculiar segregation of galaxies in the Local Universe, which has been known since the 1960s, features prominently in a recent list of "cosmic anomalies" compiled by renowned cosmologist and 2019 Nobel laureate Jim Peebles.

Now an international team led by University of Helsinki astrophysicists Till Sawala and Peter Johansson appear to have found an explanation.

In an article published in Nature Astronomy, they show how the different distributions of elliptical and disk galaxies arise naturally due to the different environments found inside and outside of the Supergalactic Plane.

"In the dense galaxy clusters that are found on the Supergalactic Plane, galaxies experience frequent interactions and mergers, which leads to the formation of ellipticals and the growth of supermassive black holes. By contrast, away from the plane, galaxies can evolve in relative isolation, which helps them preserve their spiral structure," says Till Sawala.

In their work, the team made use of the SIBELIUS (Simulations Beyond The Local Universe) simulation, that follows the evolution of the universe over 13.8 billion years, from the early universe to the present.

It was run on supercomputers in England and on CSC's Mahti supercomputer in Finland.

While most similar simulations consider random patches of the universe which cannot be directly compared to observations, the SIBELIUS simulation aims to precisely reproduce the observed structures, including the Local Supercluster.

The final simulation result is remarkably consistent with the observations.

"By chance, I was invited to a symposium in honour of Jim Peebles last December, where he presented the problem in his lecture. And I realised that we had already completed a simulation that might contain the answer," comments Till Sawala.

"Our research shows that the known mechanisms of galaxy evolution also work in this unique cosmic environment."

Read more at Science Daily

Massive Antarctic ozone hole over past four years: What is to blame?

Despite public perception, the Antarctic ozone hole has been remarkably massive and long-lived over the past four years, University of Otago researchers believe chlorofluorocarbons(CFCs) aren't the only things to blame.

In a study, just published in Nature Communications, the group analysed the monthly and daily ozone changes, at different altitudes and latitudes within the Antarctic ozone hole, from 2004 to 2022.

Lead author Hannah Kessenich, PhD candidate in the Department of Physics, says they found there is much less ozone in the centre of the ozone hole compared to 19 years ago.

"This means that the hole is not only larger in area, but also deeper throughout most of spring.

"We made connections between this drop in ozone and changes in the air that is arriving into the polar vortex above Antarctica. This reveals the recent, large ozone holes may not be caused just by CFCs," she says.

While the Montreal Protocol on Substances that Deplete the Ozone Layer, which has been in place since 1987, regulates the production and consumption of human-made chemicals known to deplete the ozone, the researchers believe other complex factors are also contributing to the ozone hole.

"Most major communications about the ozone layer over the last few years have given the public the impression that the 'ozone issue' has been solved.

"While the Montreal Protocol has vastly improved our situation with CFCs destroying ozone, the hole has been amongst the largest on record over the past three years, and in two of the five years prior to that.

"Our analysis ended with data from 2022, but as of today the 2023 ozone hole has already surpassed the size of the three years prior -- late last month it was over 26 million km2, nearly twice the area of Antarctica."

Ms Kessenich believes understanding ozone variability is important because of the major role it plays in the Southern Hemisphere's climate.

"We all know about the recent wildfires and cyclones in Australia and New Zealand and the Antarctic ozone hole is part of this picture.

"While separate from the impact of greenhouse gases on climate, the ozone hole interacts with the delicate balance in the atmosphere. Because ozone usually absorbs UV light, a hole in the ozone layer can not only cause extreme UV levels on the surface of Antarctica, but it can also drastically impact where heat is stored in the atmosphere.

"Downstream effects include changes to the Southern Hemisphere's wind patterns and surface climate, which can impact us locally."

Read more at Science Daily

Sophisticated swarming: Bacteria support each other across generations

When bacteria build communities, they cooperate and share nutrients across generations. Researchers at the University of Basel have been able to demonstrate this for the first time using a newly developed method. This innovative technique enables the tracking of gene expression during the development of bacterial communities over space and time.

In nature, bacteria usually live in communities. They collectively colonize our gut, also known as the gut microbiome, or form biofilms such as dental plaque.

Living in communities provides many advantages to the individual microbes.

They are more resilient against adverse environmental conditions, conquer new territories and benefit from each other.

Analyzing microbial communities in space and time

The development of bacterial communities is a highly complex process where bacteria form intricate three-dimensional structures.

In their latest study published in Nature Microbiology, the team led by Professor Knut Drescher from the Biozentrum of the University of Basel has investigated the development of bacterial swarm communities in detail.

They achieved a methodological breakthrough enabling them to simultaneously measure gene expression and image the behaviour of individual cells in microbial communities in space and time.

Bacteria provide resources for future generations

"We used Bacillus subtilis as a model organism. This ubiquitous bacterium is also found in our intestinal flora. We have revealed that these bacteria, which live in communities, cooperate and interact with each other across generations," explains Prof Knut Drescher, head of the study.

"Earlier generations deposit metabolites for later generations."

They also identified different subpopulations within a bacterial swarm, which produce and consume different metabolites.

Some of the metabolites secreted by one subpopulation become the food for other subpopulations that emerge later during swarm development.

Distribution of tasks within the community

The researchers combined state-of-the-art adaptive microscopy, gene expression analyses, metabolite analyses, and robotic sampling.

Using this innovative approach, the researchers have been able to simultaneously examine gene expression and bacterial behavior at precisely defined locations and specific times as well as to identify the metabolites secreted by the bacteria.

The bacterial swarm could thus be divided into three major regions: the swarm front, the intermediate region and the swarm center.

However, the three regions display gradual transitions.

"Depending on the region, the bacteria differ in appearance, characteristics and behavior. While they are mostly motile at the edges, the bacteria in the center form long non-motile threads, resulting in a 3D biofilm. One reason is the varying availability of space and resources," explains first author Hannah Jeckel.

"The spatial distribution of bacteria with distinct behavior enables the community to expand but also to hide in a protective biofilm." This process appears to be a widespread strategy in bacterial communities and is crucial for their survival.

Read more at Science Daily

NASA's Webb reveals new features in heart of Milky Way

The latest image from NASA's James Webb Space Telescope shows a portion of the dense center of our galaxy in unprecedented detail, including never-before-seen features astronomers have yet to explain. The star-forming region, named Sagittarius C (Sgr C), is about 300 light-years from the Milky Way's central supermassive black hole, Sagittarius A*.

"There's never been any infrared data on this region with the level of resolution and sensitivity we get with Webb, so we are seeing lots of features here for the first time," said the observation team's principal investigator Samuel Crowe, an undergraduate student at the University of Virginia in Charlottesville.

"Webb reveals an incredible amount of detail, allowing us to study star formation in this sort of environment in a way that wasn't possible previously."

"The galactic center is the most extreme environment in our Milky Way galaxy, where current theories of star formation can be put to their most rigorous test," added professor Jonathan Tan, one of Crowe's advisors at the University of Virginia.

Protostars

Amid the estimated 500,000 stars in the image is a cluster of protostars -- stars that are still forming and gaining mass -- producing outflows that glow like a bonfire in the midst of an infrared-dark cloud.

At the heart of this young cluster is a previously known, massive protostar over 30 times the mass of our Sun.

The cloud the protostars are emerging from is so dense that the light from stars behind it cannot reach Webb, making it appear less crowded when in fact it is one of the most densely packed areas of the image.

Smaller infrared-dark clouds dot the image, looking like holes in the starfield.

That's where future stars are forming.

Webb's NIRCam (Near-Infrared Camera) instrument also captured large-scale emission from ionized hydrogen surrounding the lower side of the dark cloud, shown cyan-colored in the image.

Typically, Crowe says, this is the result of energetic photons being emitted by young massive stars, but the vast extent of the region shown by Webb is something of a surprise that bears further investigation.

Another feature of the region that Crowe plans to examine further is the needle-like structures in the ionized hydrogen, which appear oriented chaotically in many directions.

"The galactic center is a crowded, tumultuous place. There are turbulent, magnetized gas clouds that are forming stars, which then impact the surrounding gas with their outflowing winds, jets, and radiation," said Rubén Fedriani, a co-investigator of the project at the Instituto Astrofísica de Andalucía in Spain.

"Webb has provided us with a ton of data on this extreme environment, and we are just starting to dig into it."

Around 25,000 light-years from Earth, the galactic center is close enough to study individual stars with the Webb telescope, allowing astronomers to gather unprecedented information on how stars form, and how this process may depend on the cosmic environment, especially compared to other regions of the galaxy.

For example, are more massive stars formed in the center of the Milky Way, as opposed to the edges of its spiral arms?

Read more at Science Daily

First comprehensive look at effects of 2020-2021 California megafires on terrestrial wildlife habitat

The only thing constant is change -- isn't that how the saying goes? We know that wildlife in western forests evolved with changing habitat and disturbances like wildfire. Each species responds differently, some benefiting from openings, others losing critical habitat. What we don't know is how increasing fire severity at large scales is impacting their habitat and survival, because many species are not adapted to these types of "megafires." Researchers at the Rocky Mountain Research Station set about finding some answers. They summarize their findings in "The 2020-2021 California megafires and their impacts to wildlife habitat," a paper that published today in the Proceedings of the National Academy of Sciences.

Why California and why this time period? In 2020 and 2021, California experienced fire activity unlike anything recorded in the modern record.

When the smoke cleared, the amount of burned forest totaled ten times more than the annual average going back to the late 1800s.

Nearly half of the forests that burned experienced high-severity fire, killing 75-100% of the vegetation, and much of this fire covered large continuous areas, rather than a patchy mosaic.

California's Department of Fish and Wildlife curates a comprehensive wildlife database, mapping habitat suitability of hundreds of species across the state.

Coupling that with Forest Service records of wildfires and some fancy computer footwork gave researchers an opportunity to take a broad look at how these types of "megafires" are shaping wildlife habitat within the state.

Jessalyn Ayars, the lead author, said, "Our intent was to take a broad look to gain a better understanding of the impacts of these kinds of fires on wildlife habitat as a whole." She continued, "and since each species is different, this study provides a good jumping-off point for others to be able to focus on a single species of interest or small group of species that share similar habitats."

The fires and habitat studied were mostly located in the Sierra Nevada, southern Cascades, and Klamath mountain regions of California.

Researchers looked at more than 600 wildlife species and found that for 50 species, fires spanned 15-30% of habitat within their range in the state.

One hundred species experience high severity fire over more than 10% of their geographic range within California.

Sixteen of those species are considered species of management concern, such as the great gray owl, wolverine, Pacific marten, and northern rubber boa.

Previous research shows that some species such as great gray owls may benefit from fire in terms of foraging habitat and can be somewhat resilient, but again, the unknown is whether that benefit holds true with this magnitude of habitat change in such a short time.

Some good news is that by looking more closely at some of the details around habitat change by species, scientists learned that these fires are not disproportionately impacting habitats for species of conservation concern compared to wildlife species in general, a finding that suggests that where these species live may serve as refugia for them.

Read more at Science Daily

From the first bite, our sense of taste helps pace our eating

When you eagerly dig into a long-awaited dinner, signals from your stomach to your brain keep you from eating so much you'll regret it -- or so it's been thought. That theory had never really been directly tested until a team of scientists at UC San Francisco recently took up the question.

The picture, it turns out, is a little different.

The team, led by Zachary Knight, PhD, a UCSF professor of physiology in the Kavli Institute for Fundamental Neuroscience, discovered that it's our sense of taste that pulls us back from the brink of food inhalation on a hungry day. Stimulated by the perception of flavor, a set of neurons -- a type of brain cell -- leaps to attention almost immediately to curtail our food intake.

"We've uncovered a logic the brainstem uses to control how fast and how much we eat, using two different kinds of signals, one coming from the mouth, and one coming much later from the gut," said Knight, who is also an investigator with the Howard Hughes Medical Institute and a member of the UCSF Weill Institute for Neurosciences. "This discovery gives us a new framework to understand how we control our eating."

The study, which appears Nov. 22, 2023 in Nature, could help reveal exactly how weight-loss drugs like Ozempic work, and how to make them more effective.

New views into the brainstem

Pavlov proposed over a century ago that the sight, smell and taste of food are important for regulating digestion. More recent studies in the 1970s and 1980s have also suggested that the taste of food may restrain how fast we eat, but it's been impossible to study the relevant brain activity during eating because the brain cells that control this process are located deep in the brainstem, making them hard to access or record in an animal that's awake.

Over the years, the idea had been forgotten, Knight said.

New techniques developed by lead author Truong Ly, PhD, a graduate student in Knight's lab, allowed for the first-ever imaging and recording of a brainstem structure critical for feeling full, called the nucleus of the solitary tract, or NTS, in an awake, active mouse. He used those techniques to look at two types of neurons that have been known for decades to have a role in food intake.

The team found that when they put food directly into the mouse's stomach, brain cells called PRLH (for prolactin-releasing hormone) were activated by nutrient signals sent from the GI tract, in line with traditional thinking and the results of prior studies.

However, when they allowed the mice to eat the food as they normally would, those signals from the gut didn't show up. Instead, the PRLH brain cells switched to a new activity pattern that was entirely controlled by signals from the mouth.

"It was a total surprise that these cells were activated by the perception of taste," said Ly. "It shows that there are other components of the appetite-control system that we should be thinking about."

While it may seem counterintuitive for our brains to slow eating when we're hungry, the brain is actually using the taste of food in two different ways at the same time. One part is saying, "This tastes good, eat more," and another part is watching how fast you're eating and saying, "Slow down or you're going to be sick."

"The balance between those is how fast you eat," said Knight.

The activity of the PRLH neurons seems to affect how palatable the mice found the food, Ly said. That meshes with our human experience that food is less appetizing once you've had your fill of it.

Brain cells that inspire weight-loss drugs

The PRLH-neuron-induced slowdown also makes sense in terms of timing. The taste of food triggers these neurons to switch their activity in seconds, from keeping tabs on the gut to responding to signals from the mouth.

Meanwhile, it takes many minutes for a different group of brain cells, called CGC neurons, to begin responding to signals from the stomach and intestines. These cells act over much slower time scales -- tens of minutes -- and can hold back hunger for a much longer period of time.

"Together, these two sets of neurons create a feed-forward, feed-back loop," said Knight. "One is using taste to slow things down and anticipate what's coming. The other is using a gut signal to say, 'This is how much I really ate. Ok, I'm full now!'"

The CGC brain cells' response to stretch signals from the gut is to release GLP-1, the hormone mimicked by Ozempic, Wegovy and other new weight-loss drugs.

These drugs act on the same region of the brainstem that Ly's technology has finally allowed researchers to study. "Now we have a way of teasing apart what's happening in the brain that makes these drugs work," he said.

A deeper understanding of how signals from different parts of the body control appetite would open doors to designing weight-loss regimens designed for the individual ways people eat by optimizing how the signals from the two sets of brain cells interact, the researchers said.

Read more at Science Daily

Telescope Array detects second highest-energy cosmic ray ever

In 1991, the University of Utah Fly's Eye experiment detected the highest-energy cosmic ray ever observed. Later dubbed the Oh-My-God particle, the cosmic ray's energy shocked astrophysicists. Nothing in our galaxy had the power to produce it, and the particle had more energy than was theoretically possible for cosmic rays traveling to Earth from other galaxies. Simply put, the particle should not exist.

The Telescope Array has since observed more than 30 ultra-high-energy cosmic rays, though none approaching the Oh-My-God-level energy. No observations have yet revealed their origin or how they are able to travel to the Earth.

On May 27, 2021, the Telescope Array experiment detected the second-highest extreme-energy cosmic ray. At 2.4 x 1020eV, the energy of this single subatomic particle is equivalent to dropping a brick on your toe from waist height. Led by the University of Utah (the U) and the University of Tokyo, the Telescope Array consists of 507 surface detector stations arranged in a square grid that covers 700 km2 (~270 miles2) outside of Delta, Utah in the state's West Desert. The event triggered 23 detectors at the north-west region of the Telescope Array, splashing across 48 km2 (18.5 mi2). Its arrival direction appeared to be from the Local Void, an empty area of space bordering the Milky Way galaxy.

"The particles are so high energy, they shouldn't be affected by galactic and extra-galactic magnetic fields. You should be able to point to where they come from in the sky," said John Matthews, Telescope Array co-spokesperson at the U and co-author of the study. "But in the case of the Oh-My-God particle and this new particle, you trace its trajectory to its source and there's nothing high energy enough to have produced it. That's the mystery of this -- what the heck is going on?"

In their observation that published on Nov. 24, 2023, in the journal Science, an international collaboration of researchers describe the ultra-high-energy cosmic ray, evaluate its characteristics, and conclude that the rare phenomena might follow particle physics unknown to science. The researchers named it the Amaterasu particle after the sun goddess in Japanese mythology. The Oh-My-God and the Amaterasu particles were detected using different observation techniques, confirming that while rare, these ultra-high energy events are real.

"These events seem like they're coming from completely different places in the sky. It's not like there's one mysterious source," said John Belz, professor at the U and co-author of the study. "It could be defects in the structure of spacetime, colliding cosmic strings. I mean, I'm just spit-balling crazy ideas that people are coming up with because there's not a conventional explanation."

Natural particle accelerators

Cosmic rays are echoes of violent celestial events that have stripped matter to its subatomic structures and hurled it through universe at nearly the speed of light. Essentially cosmic rays are charged particles with a wide range of energies consisting of positive protons, negative electrons, or entire atomic nuclei that travel through space and rain down onto Earth nearly constantly.

Cosmic rays hit Earth's upper atmosphere and blasts apart the nucleus of oxygen and nitrogen gas, generating many secondary particles. These travel a short distance in the atmosphere and repeat the process, building a shower of billions of secondary particles that scatter to the surface. The footprint of this secondary shower is massive and requires that detectors cover an area as large as the Telescope Array. The surface detectors utilize a suite of instrumentation that gives researchers information about each cosmic ray; the timing of the signal shows its trajectory and the amount of charged particles hitting each detector reveals the primary particle's energy.

Because particles have a charge, their flight path resembles a ball in a pinball machine as they zigzag against the electromagnetic fields through the cosmic microwave background. It's nearly impossible to trace the trajectory of most cosmic rays, which lie on the low- to middle-end of the energy spectrum. Even high-energy cosmic rays are distorted by the microwave background. Particles with Oh-My-God and Amaterasuenergy blast through intergalactic space relatively unbent. Only the most powerful of celestial events can produce them.

"Things that people think of as energetic, like supernova, are nowhere near energetic enough for this. You need huge amounts of energy, really high magnetic fields to confine the particle while it gets accelerated," said Matthews.

Ultra-high-energy cosmic rays must exceed 5 x 1019 eV. This means that a single subatomic particle carries the same kinetic energy as a major league pitcher's fast ball and has tens of millions of times more energy than any human-made particle accelerator can achieve. Astrophysicists calculated this theoretical limit, known as the Greisen-Zatsepin-Kuzmin (GZK) cutoff, as the maximum energy a proton can hold traveling over long distances before the effect of interactions of the microwave background radiation take their energy. Known source candidates, such as active galactic nuclei or black holes with accretion disks emitting particle jets, tend to be more than 160 million light years away from Earth. The new particle's 2.4 x 1020 eV and the Oh-My-God particle's 3.2 x 1020 eV easily surpass the cutoff.

Researchers also analyze cosmic ray composition for clues of its origins. A heavier particle, like iron nuclei, are heavier, have more charge and are more susceptible to bending in a magnetic field than a lighter particle made of protons from a hydrogen atom. The new particle is likely a proton. Particle physics dictates that a cosmic ray with energy beyond the GZK cutoff is too powerful for the microwave background to distort its path, but back tracing its trajectory points towards empty space.

"Maybe magnetic fields are stronger than we thought, but that disagrees with other observations that show they're not strong enough to produce significant curvature at these ten-to-the-twentieth electron volt energies," said Belz. "It's a real mystery."

Expanding the footprint

The Telescope Array is uniquely positioned to detect ultra-high-energy cosmic rays. It sits at about 1,200 m (4,000 ft), the elevation sweet-spot that allows secondary particles maximum development, but before they start to decay. Its location in Utah's West Desert provides ideal atmospheric conditions in two ways: the dry air is crucial because humidity will absorb the ultraviolet light necessary for detection; and the region's dark skies are essential, as light pollution will create too much noise and obscure the cosmic rays.

Read more at Science Daily

Protect delicate polar ecosystems by mapping biodiversity

Polar regions contain vast, undiscovered biodiversity but are both the most-threatened and least-understood areas of the world.

Now scientists led by the University of East Anglia (UEA) and the British Antarctic Survey (BAS) are calling for a roadmap of polar ecosystems to fill that knowledge gap, preserve polar life and even protect "our everyday life and our planet's health." The study would map all biodiversity in those regions, from the atmosphere to the deep sea and from land to the oceans.

The authors said concerted action is required to mitigate the impact of warming on polar ecosystems via conservation efforts, to sustainably manage these unique habitats and their ecosystem services, and for the sustainable bioprospecting of novel genes and compounds for societal gain.

'Multi-omics for studying and understanding polar life', is published today in Nature Communications. The paper is co-authored by UEA, BAS and the University of Bielefeld, Germany.

Polar ecosystems are the most threatened because they are the most sensitive to global warming. They are being lost at a rapid pace and with them all the biology that provides ecosystem services and biology-driven regulation of the climate, including the carbon cycle.

Prof Thomas Mock, Professor of Marine Microbiology in UEA's School of Environmental Sciences, is the joint lead author with Prof Melody Clark, Project Leader for the British Antarctic Survey.

Prof Thomas Mock said: "Biodiversity projections for the polar regions can only be reliably constructed if we have a sufficiently profound understanding of the diversity, ecological functions, and interrelations of polar organisms, as well as their resilience to climate change.

"These remote regions play substantial, often underappreciated, roles in the carbon cycle and drive global nutrient and dissolved organic matter fluxes. Consequently, polar environmental and ecological processes are intimately connected with our everyday life and our planet's health, much of which is underpinned by the endemic biota, from viruses to large animals.

"There is strong evidence that climate-induced changes in the polar regions are already altering species distributions on land and in the sea, with major impacts on ecosystem function."

Some species have shifted poleward, which has a knock-on effect on the food chain. Polar life, from microbes to seals, whales and polar bears, largely depends on overall low temperature and a substantial snow and ice cover, which are experiencing the impacts of global warming.

In the Arctic, temperatures are rising at least four times faster than elsewhere, destabilising the Arctic jet stream and increasing the likelihood of extreme weather events including heat waves, drought and flooding in temperate regions.

On land, permafrost melting and collapsing Arctic coastlines are dramatically altering ecological interactions and biogeochemistry due to the release of millennia-old carbon stores, trace elements, nutrients and potentially even deep-frozen ancient viruses and pathogenic bacteria.

In the oceans, the increased seasonal melting of sea ice is stabilizing surface waters too much, which reduces the amount of nutrients required for primary production to take place.

Similarly, the situation in the Southern Ocean and Antarctic continent is equally bleak, particularly for the Antarctic Peninsula, which has already experienced substantial levels of warming that has increased the loss of sea ice and glaciers.

The Southern Ocean is responsible for the uptake of three-quarters of the anthropogenic heat absorbed by the ocean and up to half of the carbon drawdown. It accounts for around 40 per cent of the global oceanic uptake of anthropogenic CO2 and around 50 per cent of the total atmospheric uptake. Furthermore, sequestering carbon by the organisms living in polar seas is probably the largest natural negative feedback against climate change.

The climate impacts on biodiversity and ecosystem functioning in both the Arctic and Antarctic serve as a bellwether for the consequences of global warming, including the persistence of biodiversity on Earth.

Prof Clark said: "Sequencing technologies have massively changed our abilities to decipher how organisms work. However the uptake in polar biology has been relatively low, especially when considering the tens of thousands of species that reside at the poles and are at threat in our warming world.

"Understanding how lots of very strange organisms living in extreme cold can help answer globally questions and provide real benefits for society. Failure to act now will result in a substantial loss of knowledge regarding evolutionary adaptation to the cold."

Genomic screening not only offers the possibility of identifying populations under stress, but it can also be used for the monitoring of invasive species, thereby facilitating early interventions.

Prof Mock said: "With the cold regions of our planet diminishing, there is a real imperative to obtain full genome sequences for diverse organisms inhabiting polar ecosystems, from the deep oceans to the permafrost on land, for both the Arctic and Antarctic. This will enable the wider application of omics technologies to polar species, which will revolutionise our understanding of evolution in the cold and adaptive responses to a warming world."

Read more at Science Daily

'Strange metal' is strangely quiet in noise experiment

True to form, a "strange metal" quantum material proved strangely quiet in recent quantum noise experiments at Rice University. Published this week in Science, the measurements of quantum charge fluctuations known as "shot noise" provide the first direct evidence that electricity seems to flow through strange metals in an unusual liquidlike form that cannot be readily explained in terms of quantized packets of charge known as quasiparticles.

"The noise is greatly suppressed compared to ordinary wires," said Rice's Douglas Natelson, the study's corresponding author.

"Maybe this is evidence that quasiparticles are not well-defined things or that they're just not there and charge moves in more complicated ways. We have to find the right vocabulary to talk about how charge can move collectively."

The experiments were performed on nanoscale wires of a quantum critical material with a precise 1-2-2 ratio of ytterbium, rhodium and silicon (YbRh2Si2), which has been studied in great depth during the past two decades by Silke Paschen, a solid-state physicist at the Vienna University of Technology (TU Wien). The material contains a high degree of quantum entanglement that produces a very unusual ("strange") temperature-dependent behavior that is very different from the one in normal metals such as silver or gold.

In such normal metals, each quasiparticle, or discrete unit, of charge is the product of incalculable tiny interactions between countless electrons.

First put forward 67 years ago, the quasiparticle is a concept physicists use to represent the combined effect of those interactions as a single quantum object for the purposes of quantum mechanical calculations.

Some prior theoretical studies have suggested that the charge in a strange metal might not be carried by such quasiparticles, and shot noise experiments allowed Natelson, study lead author Liyang Chen, a former student in Natelson's lab, and other Rice and TU Wien co-authors to gather the first direct empirical evidence to test the idea.

"The shot noise measurement is basically a way of seeing how granular the charge is as it goes through something," Natelson said.

"The idea is that if I'm driving a current, it consists of a bunch of discrete charge carriers. Those arrive at an average rate, but sometimes they happen to be closer together in time, and sometimes they're farther apart."

Applying the technique in YbRh2Si2 crystals presented significant technical challenges.

Shot noise experiments cannot be performed on single macroscopic crystals but, rather, require samples of nanoscopic dimensions.

Thus, the growth of extremely thin but nevertheless perfectly crystalline films had to be achieved, something that Paschen, Maxwell Andrews and their collaborators at TU Wien managed after almost a decade of hard work.

Next, Chen had to find a way to maintain that level of perfection while fashioning wires from these thin films that were about 5,000 times narrower than a human hair.

Rice co-author Qimiao Si, the lead theorist on the study and the Harry C. and Olga K. Wiess Professor of Physics and Astronomy, said he, Natelson and Paschen first discussed the idea for the experiments while Paschen was a visiting scholar at Rice in 2016.

Si said the results are consistent with a theory of quantum criticality he published in 2001 that he has continued to explore in a nearly two-decade collaboration with Paschen.

"The low shot noise brought about fresh new insights into how the charge-current carriers entwine with the other agents of the quantum criticality that underlies the strange metallicity," said Si, whose group performed calculations that ruled out the quasiparticle picture.

"In this theory of quantum criticality, the electrons are pushed to the verge of localization, and the quasiparticles are lost everywhere on the Fermi surface."

Natelson said the larger question is whether similar behavior might arise in any or all of the dozens of other compounds that exhibit strange metal behavior.

"Sometimes you kind of feel like nature is telling you something," Natelson said.

"This 'strange metallicity' shows up in many different physical systems, despite the fact that the microscopic, underlying physics is very different. In copper-oxide superconductors, for example, the microscopic physics is very, very different than in the heavy-fermion system we're looking at. They all seem to have this linear-in-temperature resistivity that's characteristic of strange metals, and you have to wonder is there something generic going on that is independent of whatever the microscopic building blocks are inside them."

Read more at Science Daily

'Woman the hunter': Studies aim to correct history

When Cara Ocobock was a young child, she often wondered at the images in movies, books, comics and cartoons portraying prehistoric men and women as such: "man the hunter" with spear in hand, accompanied by "woman the gatherer" with a baby strapped to her back and a basket of crop seeds in hand.

"This was what everyone was used to seeing," Ocobock said. "This was the assumption that we've all just had in our minds and that was carried through in our museums of natural history."

Many years later, Ocobock, an assistant professor in the Department of Anthropology and director of the Human Energetics Laboratory at the University of Notre Dame, found herself as a human biologist studying physiology and prehistoric evidence and discovering that many of these conceptions about early women and men weren't quite accurate. The accepted reconstruction of human evolution assumed males were biologically superior, but that interpretation wasn't telling the whole story.

Relying on both physiological and archaeological evidence, Ocobock and her research partner, Sarah Lacy, an anthropologist with expertise in biological archaeology at the University of Delaware, recently published two studies simultaneously in the journal American Anthropologist. Their joint research, coming from these two angles, found that not only did prehistoric women engage in the practice of hunting, but their female anatomy and biology would have made them intrinsically better suited for it.

Of her and her co-author's dual-pronged research, which was the cover story for the November issue of Scientific American, Ocobock said, "Rather than viewing it as a way of erasing or rewriting history, our studies are trying to correct the history that erased women from it."

Female physiology and estrogen, the 'unsung hero of life'

In their physiological study, the two researchers explained that prehistoric females were quite capable of performing the arduous physical task of hunting prey and were likely able to hunt successfully over prolonged periods of time. From a metabolic standpoint, Ocobock explained, the female body is better suited for endurance activity, "which would have been critical in early hunting because they would have had to run the animals down into exhaustion before actually going in for the kill."

Two huge contributors to that enhanced metabolism are hormones -- in this case, estrogen and adiponectin, which are typically present in higher quantities in female bodies than in male. These two hormones play a critical role in enabling the female body to modulate glucose and fat, a function that is key in athletic performance.

Estrogen, in particular, helps regulate fat metabolism by encouraging the body to use its stored fat for energy before using up its carbohydrate stores. "Since fat contains more calories than carbs do, it's a longer, slower burn," Ocobock explained, "which means that the same sustained energy can keep you going longer and can delay fatigue."

Estrogen also protects the body's cells from damage during heat exposure due to extreme physical activity. "Estrogen is really the unsung hero of life, in my mind," Ocobock said. "It is so important for cardiovascular and metabolic health, brain development and injury recovery."

Adiponectin also amplifies fat metabolism while sparing carbohydrate and/or protein metabolism, allowing the body to stay the course during extended periods, especially over great distances. In this way, adiponectin is able to protect the muscles from breaking down and keeps them in better condition for sustained exercise, Ocobock explained.

The female body structure itself is another element Ocobock and Lacy found to be of advantage in terms of endurance and effectiveness for prehistoric hunters. "With the typically wider hip structure of the female, they are able to rotate their hips, lengthening their steps," Ocobock detailed. "The longer steps you can take, the 'cheaper' they are metabolically, and the farther you can get, faster.

"When you look at human physiology this way, you can think of women as the marathon runners versus men as the powerlifters."

Archaeology tells more of the story of 'woman the hunter'

Several archaeological findings indicate prehistoric women not only shared in the resulting injuries of the dangerous business of close-contact hunting, but that it was an activity held in high esteem and valued by them. "We have constructed Neandertal hunting as an up-close-and-personal style of hunting," Ocobock said, "meaning that hunters would often have to get up underneath their prey in order to kill them. As such, we find that both males and females have the same resulting injuries when we look at their fossil records."

Ocobock described those traumatic injuries as being similar to those received by modern-day rodeo clowns -- injuries to the head and chest where they were kicked by the animal, or to the limbs where they were bitten or received a fracture. "We find these patterns and rates of wear and tear equally in both women and men," she said. "So they were both participating in ambush-style hunting of large game animals."

Second, Ocobock said, there is evidence of early female hunters in the Holocene period in Peru where females were buried with hunting weapons. "You don't often get buried with something unless it was important to you or was something that you used frequently in your life.

"Furthermore, we have no reason to believe that prehistoric women abandoned their hunting while pregnant, breastfeeding or carrying children," Ocobock added, "nor do we see in the deep past any indication that a strict sexual division of labor existed."

The bottom line, Ocobock noted, was that "hunting belonged to everyone, not just to males," especially in prehistoric societies where survival was an all-hands-on-deck activity. "There weren't enough people living in groups to be specialized in different tasks. Everyone had to be a generalist to survive."

Fighting bias

"This revelation is especially important in the current political moment of our society where sex and gender are in a spotlight," Ocobock said. "And I want people to be able to change these ideas of female physical inferiority that have been around for so long."

When talking about reconstructing the past in order to better understand it -- and to conduct "good science" -- Ocobock said scientists have to be extremely careful about how modern-day bias can seep into one's interpretations of the past. She cautioned that researchers have to be aware of their own biases and make sure they are asking the proper questions so the questions don't lead them down the road of looking for what it is they want to see.

Read more at Science Daily