Leafy greens first dished up 3,500 years ago

Over 450 prehistoric pots were examined, 66 of them contained traces of lipids, that is, substances insoluble in water. On behalf of the Nok research team at Goethe University, chemists from the University of Bristol extracted lipid profiles, with the aim of revealing which plants had been used. The results have now been published in "Archaeological and Anthropological Sciences": over a third of the 66 lipid profiles displayed very distinctive and complex distributions -- indicating that different plant species and parts had been processed.

Today, leafy vegetables, for example the cooked leaves of trees such as the baobab (Adansonia digitata) or of the shrubby -- nomen est omen -- bitter leaf (Vernonia amygdalina), accompany many West African dishes. These leafy sauces are enhanced with spices and vegetables as well as fish or meat, and complement the starchy staples of the main dish, such as pounded yam in the southern part of West Africa or thick porridge made from pearl millet in the drier savannahs in the north. By combining their expertise, archaeology and archaeobotany researchers at Goethe University and chemical scientists from the University of Bristol have corroborated that the origins of such West African dishes date back 3,500 years.

The studies are part of a project funded by the German Research Foundation, which was headed by Professor Peter Breunig and Professor Katharina Neumann and ended in December 2021. For over twelve years, archaeologists and archaeobotanists from Goethe University studied the Nok culture of Central Nigeria, which is known for its large terracotta figures and early iron production in West Africa in the first millennium BC -- although the roots of the Nok culture in fact stretch back to the middle of the second millennium. Research focused above all on the social context in which the sculptures were created, that is, including eating habits and economy. Using carbonised plant remains from Central Nigeria, it was possible to prove that the Nok people grew pearl millet. But whether they also used starchy plants, such as yam, and which dishes they prepared from the pearl millet had so far been a mystery.

"Carbonised plant remains such as seeds and nutshells preserved in archaeological sediments reflect only part of what people ate back then," explains Professor Katharina Neumann. They hoped, she says, that the chemical analyses would deliver additional insights into food preparation. And indeed, with the help of lipid biomarkers and analyses of stable isotopes, the researchers from Bristol were able to show, by examining over 450 prehistoric pots, that the Nok people included different plant species in their diet.

Dr Julie Dunne from the University of Bristol's Organic Geochemistry Unit says: "These unusual and highly complex plant lipid profiles are the most varied seen (globally) in archaeological pottery to date." There appear to be at least seven different lipid profiles in the vessels, which clearly indicates the processing of various plant species and plant organs in these vessels, possibly including underground storage organs (tubers) such as yam.

Since the beginning of the project, the archaeobotanists have sought evidence for the early use of yam. After all, the Nok region is situated in the "yam belt" of West Africa, that is, the area of the continent in which yam is nowadays grown. Carbonised remains are of no further help here because the soft flesh of the tubers is often poorly preserved and mostly non-specific as well. The chemical analyses indicate that -- apart from leaves and other as yet unidentified vegetables -- the Nok people also cooked plant tissue containing suberin. This substance is found in the periderm of both overground and underground plant organs -- possibly a first indication that yam was used, if not the unequivocal proof hoped for.

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Artificial muscles made of proteins

Dr. Stefan Schiller and Dr. Matthias Huber from the University of Freiburg's livMatS Cluster of Excellence have succeeded in developing a muscle solely on the basis of natural proteins. The autonomous contractions of the material, which the researchers presented in the journal Advanced Intelligent Systems, can be controlled with the help of pH and temperature changes. The movements are driven by a chemical reaction that consumes molecular energy for this purpose. "Our artificial muscle is still a prototype," says Schiller. "However, the high biocompatibility of the material and the possibility of adjusting its composition to match particular tissue could pave the way for future applications in reconstructive medicine, prosthetics, pharmaceutics, or soft robotics."

In the past, scientists have already taken natural proteins as a basis for developing artificial muscle systems and built them into miniscule molecular machines or into polymers. However, it has not yet been possible to develop synthetic muscle materials that are entirely bio-based and move autonomously with the help of chemical energy.

Material based on the natural protein elastin

The material used by the Freiburg team is based on elastin, a natural fibrous protein that also occurs in humans, for instance giving elasticity to the skin and blood vessels. Following the model of this protein, the researchers developed two elastin-like proteins, one of which responds, for example, to fluctuations in pH, the other to changes in temperature. The scientists combined the two proteins by means of photochemical cross-linking to form a bilayered material. It is possible in this process to flexibly shape the material and set the direction of its movement.

Contractions can be switched on and off with the help of temperature changes

The researchers succeeded in inducing the rhythmic contractions by using a chemical energy source as fuel, in this case sodium sulfite. In an oscillating chemical reaction in which the pH changes in cycles due to a special linkage of several reactions, the added energy was converted into mechanical energy via non-equilibrium states of the material. In this way, the researchers induced the material to contract autonomously in a cyclical manner. They were also able to switch the contractions on and off with the help of temperature changes: The oscillating chemical reaction started at a temperature of around 20 degrees Celsius, and the material began to make rhythmic movements. In the process, it was possible to program certain states for the material to assume and to reset them again with another stimulus. The scientists thus achieved a simple system for implementing learning and forgetting at the material level.

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What wintering squirrels can teach astronauts

When bears and ground squirrels hibernate in winter, they stop eating, lasting until spring simply on the fat reserves they've stored up in their bodies. Usually, this sort of prolonged fasting and inactivity would significantly reduce the mass and function of muscle, but hibernators don't suffer this fate. How they avoid it, however, has been a mystery.

Now, in research published in Science, an Université de Montréal biologist has figured out why, and his findings could have implications for, of all things, the future of space travel . By studying a variety called the 13-lined ground squirrel that is common in North America, Matthew Regan has confirmed a theory known as "urea nitrogen salvage" dating back to the 1980s.

The theory posits that hibernators harness a metabolic trick of their gut microbes to recycle the nitrogen present in urea, a waste compound that is usually excreted as urine, and use it to build new tissue proteins.

How could this discovery be of use in space? Theoretically, Regan posits, by helping astronauts minimize their own muscle-loss problems caused by microgravity-induced suppression of protein synthesis and which they now try to reduce by intensively exercising.

If a way could be found to augment the astronauts' muscle protein synthesis processes using urea nitrogen salvage, they could be able to achieve better muscle health during long voyages into deep space in spacecraft too small for the usual exercise equipment, the argument goes.

"Because we know which muscle proteins are suppressed during spaceflight, we can compare these proteins with those that are enhanced by urea nitrogen salvage during hibernation," said Regan, who carried out this research while a postdoc at the University of Wisconsin-Madison.

He is now continuing his work through a Canadian Space Agency research grant at UdeM, where he last year took up a position as assistant professor of animal physiology in the Department of Biological Sciences.

"If," Regan continued, "there is an overlap between the proteins in spaceflight and the ones from hibernation, then it suggests this process may have benefits to muscle health during spaceflight."

A model hibernator

In his study, Regandesigned a series of techniques and experiments to investigate the major steps in the urea salvage process and provide evidence for whether or not they occur in the 13-lined ground squirrel when it hibernates.

To do that, in their lab they injected their test squirrels' blood with "double-labeled" urea, meaning the urea's carbon atom was 13C instead of the usual 12C, and its nitrogen atoms were 15N instead of the usual 14N. These labels allowed them to track the urea-sourced carbon and nitrogen through the different steps of the urea nitrogen salvage process.

That process, they found, led from the initial transport of urea from the blood into the gut, to the breakdown of urea into its component parts by gut microbes, to the flow of substances -- called metabolites -- containing urea nitrogen back into the animal, and finally to the eventual appearance of this urea nitrogen in tissue protein.

"Essentially, seeing 13C and/or 15N in metabolites at these various steps indicated that they originated from urea, and thus, that the hibernator was using urea nitrogen salvage," said Regan.

He did his experiments on squirrels with and without gut microbiomes at three times of the year: summer, when they were active and not hibernating; early winter, when they were one month into fasting and hibernation; and late winter, when they were four months into fasting and hibernation.

'Clear evidence of nitrogen salvage'

What they found was definitive: at each step of the process, there was clear evidence of urea nitrogen salvage by the squirrels with intact gut microbiomes.

Importantly, the squirrels with depleted gut microbiomes displayed no evidence of urea nitrogen salvage at any step, confirming this process was wholly dependent on the gut microbes' ability to degrade urea, something the squirrels themselves cannot do.

Regan and his team also made two other important findings:
 

• First, the incorporation of urea nitrogen into the tissue protein of the squirrels was highest during late winter, suggesting that urea nitrogen salvage becomes more active as the hibernation season proceeds. This is unlike most physiological processes during hibernation, when tend to be significantly reduced.
• Second, there was evidence the microbes themselves were using the urea nitrogen to build their own new proteins, which is useful for them because they, like the squirrel, are under conditions of fasting hibernation. Thus, both the squirrel and its microbes benefit from urea nitrogen salvage, which makes this process a true symbiosis.

What this means, Regan said, is that the squirrels emerge from hibernation in the spring in good shape. This is important because the year's only mating season, which is a time of intense physical activity for both males and females, occurs directly after they emerge from hibernation. Tissue function -- particularly muscle tissue function -- is therefore highly important for a successful mating season.

"By facilitating muscle protein synthesis late in the hibernation season, urea nitrogen salvage may help optimize the emerging squirrels' muscle function and contribute to their reproductive success during the mating season," said Regan. "Urea nitrogen salvage may therefore enhance the animals' overall biological fitness."

Starving masses and the elderly

Beyond the implications for space travel and the health of astronauts, Regan's discovery could have more immediate impacts now right here on Earth -- in the starving masses of the underdeveloped world, and in the elderly.

Hundreds of millions of people globally experience muscle wasting as a consequence of various conditions -- undernourishment, for instance, affects over 805 million people globally. More prevalent in Canada is sarcopenia, an age-related decline in muscle mass stemming from anabolic insensitivity that affects all humans, leading to a 30- to 50-per-cent decline in skeletal muscle mass between the ages 40 and 80.

"The mechanisms that mammals like the 13-lined ground squirrel have naturally evolved to maintain protein balance in their own nitrogen-limited situations may inform strategies for maximizing the health of other nitrogen-limited animals, including humans," said Regan. One solution might be to develop a pre- or probiotic pill that people could take to promote a gut microbiome of the kind that hibernators like squirrels have.

"To be clear, these applications, though theoretically possible, are a long way from delivery, and a lot of additional work is needed to translate this naturally evolved mechanism safely and effectively to humans," Regan said.

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Extreme exoplanet has a complex and exotic atmosphere

An international team including researchers from the University of Bern and the University of Geneva as well as the National Centre of Competence in Research (NCCR) PlanetS analyzed the atmosphere of one of the most extreme known planets in great detail. The results from this hot, Jupiter-like planet that was first characterized with the help of the CHEOPS space telescope, may help astronomers understand the complexities of many other exoplanets -- including Earth-like planets.

The atmosphere of Earth is not a uniform envelope but consists of distinct layers that each have characteristic properties. The lowest layer that spans from sea level beyond the highest mountain peaks, for example -- the troposphere -, contains most of the water vapour and is thus the layer in which most weather phenomena occur. The layer above it -- the stratosphere -- is the one that contains the famous ozone layer that shields us from the Sun's harmful ultraviolet radiation.

In a new study that appeared in the journal Nature Astronomy, an international team of researchers led by the University of Lund show for the first time that the atmosphere of one of the most extreme known planets may have similarly distinct layers as well -- albeit with very different characteristics.

An exotic cocktail for an atmosphere

WASP-189b is a planet outside our own solar system, located 322 light years from Earth. Extensive observations with the CHEOPS space telescope in 2020 revealed among other things that the planet is 20 times closer to its host star than Earth is to the Sun and has a daytime temperature of 3200 degrees Celsius. More recent investigations with the HARPS spectrograph at the La Silla Observatory in Chile now for the first time allowed the researchers to take a closer look at the atmosphere of this Jupiter-like planet.

"We measured the light coming from the planet's host star and passing through the planet's atmosphere. The gases in its atmosphere absorb some of the starlight, similar to Ozone absorbing some of the sunlight in Earth's atmosphere, and thereby leave their characteristic 'fingerprint'. With the help of HARPS, we were able to identify the corresponding substances," lead author of the study and doctoral student at Lund University, Bibiana Prinoth, explains. According to the researchers, the gases that left their fingerprints in the atmosphere of WASP-189b included iron, chromium, vanadium, magnesium and manganese.

An "Ozone layer" on a blisteringly hot planet?

One particularly interesting substance the team found is a gas containing titanium: titanium oxide. While titanium oxide is very scarce on Earth, it could play an important role in the atmosphere of WASP-189b -- similar to that of ozone in Earth's atmosphere. "Titanium oxide absorbs short wave radiation, such as ultraviolet radiation. Its detection could therefore indicate a layer in the atmosphere of WASP-189b that interacts with the stellar irradiation similarly to how the Ozone layer does on Earth," study co-author Kevin Heng, a professor of astrophysics at the University of Bern and a member of the NCCR PlanetS, explains.

Indeed, the researchers found hints of such a layer and other layers on the ultra-hot Jupiter-like planet. "In our analysis, we saw that the 'fingerprints' of the different gases were slightly altered compared to our expectation. We believe that strong winds and other processes could generate these alterations. And because the fingerprints of different gases were altered in different ways, we think that this indicates that they exist in different layers -- similarly to how the fingerprints of water vapour and ozone on Earth would appear differently altered from a distance, because they mostly occur in different atmospheric layers," Prinoth explains. These results may change how astronomers investigate exoplanets.

A different way to look at exoplanets

"In the past, astronomers often assumed that the atmospheres of exoplanets exist as a uniform layer and try to understand it as such. But our results demonstrate that even the atmospheres of intensely irradiated giant gas planets have complex three-dimensional structures," study co-author and associate senior lecturer at Lund University Jens Hoeijmakers points out.

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A mathematical secret of lizard camouflage

The shape-shifting clouds of starling birds, the organization of neural networks or the structure of an anthill: nature is full of complex systems whose behaviors can be modeled using mathematical tools. The same is true for the labyrinthine patterns formed by the green or black scales of the ocellated lizard. A multidisciplinary team from the University of Geneva (UNIGE) explains, thanks to a very simple mathematical equation, the complexity of the system that generates these patterns. This discovery contributes to a better understanding of the evolution of skin color patterns: the process allows for many different locations of green and black scales but always leads to an optimal pattern for the animal survival. These results are published in the journal Physical Review Letters.

A complex system is composed of several elements (sometimes only two) whose local interactions lead to global properties that are difficult to predict. The result of a complex system will not be the sum of these elements taken separately since the interactions between them will generate an unexpected behavior of the whole. The group of Michel Milinkovitch, Professor at the Department of Genetics and Evolution, and Stanislav Smirnov, Professor at the Section of Mathematics of the Faculty of Science of the UNIGE, have been interested in the complexity of the distribution of colored scales on the skin of ocellated lizards.

Labyrinths of scales

The individual scales of the ocellated lizard (Timon lepidus) change color (from green to black, and vice versa) over the course of the animal's life, gradually forming a complex labyrinthine pattern as it reaches adulthood. The UNIGE researchers have previously shown that the labyrinths emerge on the skin surface because the network of scales constitutes a so-called 'cellular automaton'. "This is a computing system invented in 1948 by the mathematician John von Neumann in which each element changes its state according to the states of the neighboring elements," explains Stanislav Smirnov.

In the case of the ocellated lizard, the scales change state -- green or black -- depending on the colors of their neighbors according to a precise mathematical rule. Milinkovitch had demonstrated that this cellular automaton mechanism emerges from the superposition of, on one hand, the geometry of the skin (thick within scales and much thinner between scales) and, on the other hand, the interactions among the pigmentary cells of the skin.

The road to simplicity

Szabolcs Zakany, a theoretical physicist in Michel Milinkovitch's laboratory, teamed up with the two professors to determine whether this change in the color of the scales could obey an even simpler mathematical law. The researchers thus turned to the Lenz-Ising model developed in the 1920's to describe the behavior of magnetic particles that possess spontaneous magnetization. The particles can be in two different states (+1 or -1) and interact only with their first neighbors.

"The elegance of the Lenz-Ising model is that it describes these dynamics using a single equation with only two parameters: the energy of the aligned or misaligned neighbors, and the energy of an external magnetic field that tends to push all particles toward the +1 or -1 state," explains Szabolcs Zakany.

A maximum disorder for a better survival

The three UNIGE scientists determined that this model can accurately describe the phenomenon of scale color change in the ocellated lizard. More precisely, they adapted the Lenz-Ising model, usually organized on a square lattice, to the hexagonal lattice of skin scales. At a given average energy, the Lenz-Ising model favors the formation of all state configurations of magnetic particles corresponding to this same energy. In the case of the ocellated lizard, the process of color change favors the formation of all distributions of green and black scales that each time result in a labyrinthine pattern (and not in lines, spots, circles, or single-colored areas...).

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Cosmic physics mimicked on table-top as graphene enables Schwinger effect

Researchers at The University of Manchester have succeeded in observing the so-called Schwinger effect, an elusive process that normally occurs only in cosmic events. By applying high currents through specially designed graphene-based devices, the team -- based at the National Graphene Institute -- succeeded in producing particle-antiparticle pairs from a vacuum.

A vacuum is assumed to be completely empty space, without any matter or elementary particles. However, it was predicted by Nobel laureate Julian Schwinger 70 years ago that intense electric or magnetic fields can break down the vacuum and spontaneously create elementary particles.

This requires truly cosmic-strength fields such as those around magnetars or created transitorily during high-energy collisions of charged nuclei. It has been a long-standing goal of particle physics to probe these theoretical predictions experimentally and some are currently planned for high-energy colliders around the world.

Now the research team -- led by another Nobel laureate, Prof Sir Andre Geim in collaboration with colleagues from UK, Spain, US and Japan -- has used graphene to mimic the Schwinger production of electron and positron pairs.

In January 2022 issue of Science, they report specially designed devices such as narrow constrictions and superlattices made from graphene, which allowed the researchers to achieve exceptionally strong electric fields in a simple, table-top setup. Spontaneous production of electron and hole pairs was clearly observed (holes are a solid-state analogue of positrons) and the process' details agreed well with theoretical predictions.

The scientists also observed another unusual high-energy process that so far has no analogies in particle physics and astrophysics. They filled their simulated vacuum with electrons and accelerated them to the maximum velocity allowed by graphene's vacuum, which is 1/300 of the speed of light. At this point, something seemingly impossible happened: electrons seemed to become superluminous, providing an electric current higher than allowed by general rules of quantum condensed matter physics. The origin of this effect was explained as spontaneous generation of additional charge carriers (holes). Theoretical description of this process provided by the research team is rather different from the Schwinger one for the empty space.

"People usually study the electronic properties using tiny electric fields that allows easier analysis and theoretical description. We decided to push the strength of electric fields as much as possible using different experimental tricks not to burn our devices," said the paper's first author Dr Alexey Berduygin.

Co-lead author Dr Na Xin added: "We just wondered what could happen at this extreme. To our surprise, it was the Schwinger effect rather than smoke coming out of our set-up."

Dr Roshan Krishna Kumar, another leading contributor, said: "When we first saw the spectacular characteristics of our superlattice devices, we thought 'wow … it could be some sort of new superconductivity'. Although the response closely resembles that routinely observed in superconductors, we soon found that the puzzling behaviour was not superconductivity but rather something in the domain of astrophysics and particle physics. It is curious to see such parallels between distant disciplines."

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Even light drinking can be harmful to health

Drinking less than the UK's recommended limit of 14 units of alcohol per week still increases the risk of cardiovascular issues such as heart and cerebrovascular disease, according to new research published in the journal Clinical Nutrition.

Academics from Anglia Ruskin University (ARU) examined hospitalisations related to cardiovascular events among more than 350,000 UK residents aged between 40 and 69 from data obtained from the UK Biobank study.

The sample included 333,259 people who drank alcohol. Participants had been asked about their overall weekly alcohol intake and their intake of specific types of alcohol including beer, wine and spirits. Those participants were followed up for a median of approximately seven years, capturing all incidents where patients had been hospitalised through cardiovascular events.

Anyone who had suffered a previous cardiovascular event was excluded from the analysis, as were former drinkers or those who had not completed information on alcohol intake.

The analysis found that, for those participants that drank less than 14 units of alcohol per week -- the limit recommended by the UK's Chief Medical Officers -- each additional 1.5 pints of beer at 4% strength (alcohol by volume) is associated with a 23% increased risk of suffering a cardiovascular event.

The authors argue that biases in existing epidemiological evidence have resulted in the widespread acceptance of the "J-shaped curve" that wrongly suggests low to moderate alcohol consumption can be beneficial to cardiovascular health.

These biases include using non-drinkers as a reference group when many do not drink for reasons of existing poor health, pooling of all drink types when determining the alcohol intake of a study population, and embedding the lower risk observed of coronary artery disease among wine drinkers, potentially distorting the overall cardiovascular risk from the drink.

Lead author Dr Rudolph Schutte, course leader for the BSc Hons Medical Science programme and Associate Professor at ARU, said:

"The so-called J-shaped curve of the cardiovascular disease-alcohol consumption relationship suggesting health benefit from low to moderate alcohol consumption is the biggest myth since we were told smoking was good for us.

"Among drinkers of beer, cider and spirits in particular, even those consuming under 14 units a week had an increased risk of ending up in hospital through a cardiovascular event involving the heart or the blood vessels. While we hear much about wine drinkers having lower risk of coronary artery disease, our data shows their risk of other cardiovascular events is not reduced.

"Biases embedded in epidemiological evidence mask or underestimate the hazards associated with alcohol consumption. When these biases are accounted for, the adverse effects of even low-level alcohol consumption are revealed.

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Physicist solves century old problem of radiation reaction

A Lancaster physicist has proposed a radical solution to the question of how a charged particle, such as an electron, responded to its own electromagnetic field.

This question has challenged physicists for over 100 years but mathematical physicist Dr Jonathan Gratus has suggested an alternative approach -- published in the Journal of Physics A- with controversial implications.

It is well established that if a point charge accelerates it produces electromagnetic radiation. This radiation has both energy and momentum, which must come from somewhere. It is usually assumed that they come from the energy and momentum of the charged particle, damping the motion.

The history of attempts to calculate this radiation reaction (also known as radiation damping) date back to Lorentz in 1892. Major contributions were then made by many well known physicists including Plank, Abraham, von Laue, Born, Schott, Pauli, Dirac and Landau. Active research continues to this day with many articles published every year.

The challenge is that according to Maxwell's equations, the electric field at the actual point where the point particle is, is infinite. Hence the force on that point particle should also be infinite.

Various methods have been used to renormalise away this infinity. This leads to the well established Lorentz-Abraham-Dirac equation.

Unfortunately, this equation has well known pathological solutions. For example, a particle obeying this equation may accelerate forever with no external force or accelerate before any force is applied. There is also the quantum version of radiation damping. Ironically, this is one of the few phenomena where the quantum version occurs at lower energies than the classical one.

Physicists are actively searching for this effect. This requires `colliding' very high energy electrons and powerful laser beams, a challenge as the biggest particle accelerators are not situated near the most powerful lasers. However, firing lasers into plasmas will produce high energy electron, which can then interact with the laser beam. This only requires a powerful laser. Current results show that quantum radiation reaction does exist.

The alternative approach is to consider many charged particles, where each particle responds to the fields of all the other charged particles, but not itself. This approach was hitherto dismissed, since it was assumed that this would not conserve energy and momentum.

However, Dr Gratus shows that this assumption is false, with the energy and momentum of one particle's radiation coming from the external fields used to accelerate it.

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Scientists explain mysterious finger-like features in solar flares

In January 1999, scientists observed mysterious motions within a solar flare.

Unlike typical flares that showed bright energy erupting outwards from the Sun, this solar flare also displayed a downward flow of motion, as if material was falling back towards the Sun. Described as "downward-moving dark voids," astronomers wondered what exactly they were seeing.

Now, in a study published today in Nature Astronomy, astronomers at the Center for Astrophysics | Harvard & Smithsonian (CfA) offer a new explanation for the poorly understood downflows, now referred to as supra-arcade downflows (SADs) by the scientific community.

"We wanted to know how these structures occur," says lead author and CfA astronomer Chengcai Shen, who describes the structures as "dark finger-like features." "What's driving them and are they truly tied to magnetic reconnection?"

Scientists have assumed that SADs are tied to magnetic reconnection since their discovery in the 90s. The process occurs when magnetic fields break, releasing fast moving and extremely energetic radiation, and then reform.

"On the Sun, what happens is you have a lot of magnetic fields that are pointing in all different directions. Eventually the magnetic fields are pushed together to the point where they reconfigure and release a lot of energy in the form of a solar flare," says study co-author and CfA astronomer Kathy Reeves.

Reeves adds, "It's like stretching out a rubber band and snipping it in the middle. It's stressed and stretched thin, so it's going to snap back."

Scientists assumed the dark downflows were signs of the broken magnetic fields "snapping back" to the Sun after a solar flare eruption.

But there was a catch.

Most of the downflows observed by scientists are "puzzlingly slow," says co-author Bin Chen, an astronomer at the New Jersey Institute of Technology.

Shen explains, "This is not predicted by classic reconnection models, which show the downflows should be much quicker. It's a conflict that requires some other explanation."

To find out what was happening, the team analyzed downflow images captured by the Atmospheric Imaging Assembly (AIA) onboard NASA's Solar Dynamics Observatory. Designed and built partially at the CfA and led by the Lockheed Martin Solar Astrophysics Laboratory, the AIA takes images of the Sun every twelve seconds in seven different wavelengths of light to measure variations in the Sun's atmosphere.

They then made 3D simulations of solar flares and compared them to the observations.

The results show that most SADs are not generated by magnetic reconnection after all. Instead, they form on their own in the turbulent environment and are the result of two fluids with different densities interacting.

Reeves says scientists are essentially seeing the same thing that happens when water and oil are mixed together: the two different fluid densities are unstable and ultimately separate.

"Those dark, finger-like voids are actually an absence of plasma. The density is much lower there than the surrounding plasma," Reeves says.

The team plans to continue studying SADs and other solar phenomenon using 3D simulations to better understand magnetic reconnection. By understanding the processes that drive solar flares and eruptions from the Sun, they may ultimately help develop tools to forecast space weather and mitigate its impacts.

Read more at Science Daily

Even dim light before bedtime may disrupt a preschooler’s sleep

Even slight exposure to light can prompt the critical sleep-promoting hormone melatonin to plummet in preschoolers in the hour before bedtime, potentially disrupting slumber long after the light goes out, according to new CU Boulder research.

The study, published this month, is the latest in a series, funded by the National Institutes of Health, examining how the central body clock of young children is unique. It suggests that preschoolers are highly susceptible to the physiological impacts of light at night, and some children may be even more sensitive than others.

"Our previous work showed that one, fairly high intensity of bright light before bedtime dampens melatonin levels by about 90% in young children," said first author Lauren Hartstein, a postdoctoral fellow in the Sleep and Development Lab at CU Boulder. "With this study, we were very surprised to find high melatonin suppression across all intensities of light, even dim ones."

Light: The body's strongest time cue

Light is the body's primary time cue, influencing circadian rhythms that regulate everything from when we feel tired or hungry to what our body temperature is throughout the day.

When light hits the retina, a signal transmits to a part of the brain called the suprachiasmatic nucleus, which coordinates rhythms throughout the body, including nightly production of melatonin. If this exposure happens in the evening as melatonin is naturally increasing, it can slow or halt it, delaying the body's ability to transition into biological nighttime.

Because children's eyes have larger pupils and more transparent lenses than adults, light streams into them more freely. (One recent study showed that the transmission of blue light through a 9-year-old's eye is 1.2-times higher than that of an adult).

"Kids are not just little adults," said senior author Monique LeBourgeois, an associate professor of Integrative Physiology and one of the few researchers in the world to study the circadian biology of young children. "This heightened sensitivity to light may make them even more susceptible to dysregulation of sleep and the circadian system."

Research in a "cave"

To quantify how susceptible they are, the researchers collaborated with Colorado School of Mines mathematician Cecilia Diniz Behn for a new study.

They enlisted 36 healthy children, ages 3 to 5 years, for a nine-day protocol in which they wore a wrist monitor that tracked their sleep and light exposure. For seven days, parents kept the children on a stable sleep schedule to normalize their body clocks and settle them into a pattern in which their melatonin levels rose at about the same time each evening.

On the eighth day, researchers transformed the children's home into what they playfully described as a "cave" -- with black plastic on the windows and lights dimmed -- and took saliva samples every half hour starting in the early afternoon until after bedtime. This enabled the scientists to get a baseline of when the children's biological night naturally began and what their melatonin levels were.

On the last day of the study, the young study subjects were asked to play games on a light table in the hour before bedtime, a posture similar to a person looking at a glowing phone or tablet. Light intensity varied between individual children, ranging from 5 lux to 5,000 lux. (One lux is defined as the light from a candle 1 meter, or about 3 feet, away).

When compared to the previous night with minimal light, melatonin was suppressed anywhere from 70% to 99% after light exposure. Surprisingly, the researchers found little-to-no relationship between how bright the light was and how much the key sleep hormone fell. In adults, this intensity-dependent response has been well documented.

Even in response to light measured at 5 to 40 lux, which is much dimmer than typical room light, melatonin fell an average of 78%. And even 50 minutes after the light extinguished, melatonin did not rebound in more than half of children tested.

"Together, our findings indicate that in preschool-aged children, exposure to light before bedtime, even at low intensities, results in robust and sustained melatonin suppression," said Hartstein.

What parents can do

This does not necessarily mean that parents must throw away the nightlight and keep children in absolute darkness before bedtime. But at a time when half of children use screen media before bed, the research serves as a reminder to all parents to shut off the gadgets and keep light to a minimum to foster good sleep habits in their kids. Notably, a tablet at full brightness held 1 foot from the eyes in a dark room measures as much as 100 lux.

Read more at Science Daily

Ancient ice reveals mysterious solar storm

Through analysis of ice cores from Greenland and Antarctica, a research team led by Lund University in Sweden has found evidence of an extreme solar storm that occurred about 9,200 years ago. What puzzles the researchers is that the storm took place during one of the sun's more quiet phases -- during which it is generally believed our planet is less exposed to such events.

The sun is a prerequisite for life on Earth. But our life-giving companion can also cause problems. When there is strong activity on the surface of the sun, more energy is released, something that can give rise to geomagnetic storms. This in turn can cause power outages and communication disturbances.

Predicting solar storms is difficult. It is currently believed that they are more likely during an active phase of the sun, or solar maximum, during the so-called sunspot cycle. However, the new study published in Nature Communications shows that this may not always be the case for very large storms.

"We have studied drill cores from Greenland and Antarctica, and discovered traces of a massive solar storm that hit Earth during one of the sun's passive phases about 9,200 years ago," says Raimund Muscheler, geology researcher at Lund University.

The researchers scoured the drill cores for peaks of the radioactive isotopes beryllium-10 and chlorine-36. These are produced by high-energy cosmic particles that reach Earth, and can be preserved in ice and sediment.

"This is time consuming and expensive analytical work. Therefore, we were pleasantly surprised when we found such a peak, indicating a hitherto unknown giant solar storm in connection with low solar activity," says Raimund Muscheler.

If a similar solar storm were to take place today, it could have devastating consequences. In addition to power outages and radiation damage to satellites, it could pose a danger to air traffic and astronauts as well as a collapse of various communication systems.

Read more at Science Daily

Suitable growing regions for coffee, cashews, and avocados predicted to shift as Earth warms

A new analysis predicts that, as climate change progresses, the most suitable regions for growing coffee arabica, cashews, and avocados will decline in some of the main countries that produce these crops. Roman Grüter and colleagues at Zurich University of Applied Sciences, Switzerland, present these findings in the open-access journal PLOS ONE on January 26, 2022.

Coffee, cashews, and avocados are important crops for consumers and for tropical small-scale farmers around the world. Extensive research suggests that climate change will reduce suitability for growing coffee arabica—the dominant coffee species—in most regions where it is currently grown. However, such studies have not considered land and soil characteristics that could also impact suitability. Meanwhile, no studies have addressed how climate change will impact avocado and cashew suitability at a global scale.

To address these knowledge gaps, Grüter and colleagues combined climate change projections and soil factors to computationally model and predict how suitable different regions worldwide will be for growing coffee, cashews, and avocados in 2050. They used projections from 14 global climate models under three different future emission scenarios and incorporated land and soil requirements for the crops, such as pH, texture, and slope.

The analysis predicts that some regions will become more suitable and some less suitable for each crop. Coffee is the most susceptible of the three, with predicted declines in suitability in all major producing regions, including Brazil, Vietnam, Indonesia, and Colombia. For cashews, highly suitable regions are predicted to decrease in some major producing countries, including India, Côte d’Ivoire, and Benin. Suitable areas for avocados will also decline for some major producers, such as the Dominican Republic, Peru, and Indonesia.

Meanwhile, areas suitable for all three crops may expand at higher altitudes and latitudes, especially for cashews and avocados. Areas with greater future suitability are located in regions such as the United States, Argentina, China, and East Africa.

These findings suggest the need for climate change adaptations in major producing countries, such as breeding for varieties adapted to higher temperatures or drought. Strategies will also be needed to mitigate the environmental impact of any expansion to new locations.

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Mysterious object unlike anything astronomers have seen before

A team mapping radio waves in the Universe has discovered something unusual that releases a giant burst of energy three times an hour, and it's unlike anything astronomers have seen before.

The team who discovered it think it could be a neutron star or a white dwarf -- collapsed cores of stars -- with an ultra-powerful magnetic field.

Spinning around in space, the strange object sends out a beam of radiation that crosses our line of sight, and for a minute in every twenty, is one of the brightest radio sources in the sky.

Astrophysicist Dr Natasha Hurley-Walker, from the Curtin University node of the International Centre for Radio Astronomy Research, led the team that made the discovery.

"This object was appearing and disappearing over a few hours during our observations," she said.

"That was completely unexpected. It was kind of spooky for an astronomer because there's nothing known in the sky that does that.

"And it's really quite close to us -- about 4000 lightyears away. It's in our galactic backyard."

The object was discovered by Curtin University Honours student Tyrone O'Doherty using the Murchison Widefield Array (MWA) telescope in outback Western Australia and a new technique he developed.

"It's exciting that the source I identified last year has turned out to be such a peculiar object," said Mr O'Doherty, who is now studying for a PhD at Curtin.

"The MWA's wide field of view and extreme sensitivity are perfect for surveying the entire sky and detecting the unexpected."

Objects that turn on and off in the Universe aren't new to astronomers -- they call them 'transients'.

ICRAR-Curtin astrophysicist and co-author Dr Gemma Anderson said that "when studying transients, you're watching the death of a massive star or the activity of the remnants it leaves behind."

'Slow transients' -- like supernovae -- might appear over the course of a few days and disappear after a few months.

'Fast transients' -- like a type of neutron star called a pulsar -- flash on and off within milliseconds or seconds.

But Dr Anderson said finding something that turned on for a minute was really weird.

She said the mysterious object was incredibly bright and smaller than the Sun, emitting highly-polarised radio waves -- suggesting the object had an extremely strong magnetic field.

Dr Hurley-Walker said the observations match a predicted astrophysical object called an 'ultra-long period magnetar'.

"It's a type of slowly spinning neutron star that has been predicted to exist theoretically," she said.

"But nobody expected to directly detect one like this because we didn't expect them to be so bright.

"Somehow it's converting magnetic energy to radio waves much more effectively than anything we've seen before."

Dr Hurley-Walker is now monitoring the object with the MWA to see if it switches back on.

"If it does, there are telescopes across the Southern Hemisphere and even in orbit that can point straight to it," she said.

Dr Hurley-Walker plans to search for more of these unusual objects in the vast archives of the MWA.

"More detections will tell astronomers whether this was a rare one-off event or a vast new population we'd never noticed before," she said.

MWA Director Professor Steven Tingay said the telescope is a precursor instrument for the Square Kilometre Array -- a global initiative to build the world's largest radio telescopes in Western Australia and South Africa.

"Key to finding this object, and studying its detailed properties, is the fact that we have been able to collect and store all the data the MWA produces for almost the last decade at the Pawsey Research Supercomputing Centre. Being able to look back through such a massive dataset when you find an object is pretty unique in astronomy," he said.

"There are, no doubt, many more gems to be discovered by the MWA and the SKA in coming years."

Read more at Science Daily

Urban greening 'not a panacea' for dealing with extreme weather

Urban greening is unlikely to provide a single fix for tackling extreme weather events brought on by climate change, scientists have suggested.

A team led by researchers from Cardiff University has shown that the majority of cities around the world will not be able to reduce instances of heatwaves and flooding at the same time through the introduction of strategies such as green roofs, living walls, vegetated urban spaces and parks.

Publishing their findings today in the journal Nature Communications, the team show that the cooling or flood-reducing potential of green urban spaces depends strongly on the prevailing climate of the city in question, with flood protection likely to be more successful in arid environments, whilst a cooling effect more likely in more humid climates.

Urban areas each have unique climates that pose significant risks, even more so as climate change increases the likelihood and severity of extreme weather events in the future.

Heatwaves within our cities can be attributed to the urban heat island effect (UHI), caused by the predominance of concrete and steel that absorb and retain heat, and the lack of cooling by water evaporating from plants. Flooding is part of the urban stream syndrome (USS), whereby city structures and systems negatively affect the natural runoff of rainwater back into the environment.

To tackle these problems, a commonly proposed strategy is to implement urban greening in our cities in the form of green roofs, living walls, vegetated urban spaces or parks.

Not only can these measures reduce the UHI and USS effects in our cities, they can also support local wildlife, reduce pollution and improve the general wellbeing of local populations.

In their study, the team used global climate model outputs and weather information from 175 cities around the world spanning 15 years of daily observations, from 2000 to 2015.

This data was used in conjunction with theories taken from soil science to calculate water infiltration into soils, which act like a sponge to reduce rainwater runoff, and the evaporation of water from plants, which can induce the desired cooling effect.

"Our research found that the ability of urban greening to mitigate local flooding and excess heat is not automatic nor, in some areas, even possible," said lead author of study Dr Mark Cuthbert, from Cardiff University's School of Earth and Environmental Sciences.

"Local and regional climatic conditions significantly impact the capacity of urban soils and plant growth to simultaneously defend against flooding and extreme heating. In fact, our findings indicate that in many, possibly the majority, of global cities, urban greening will not be able to mitigate cooling and flooding at the same time."

The team also found that increasing variability in rainfall patterns due to climate change may reduce the performance of thinner green structures, such as green roofs, more quickly compared to larger greened areas with thicker soils and root systems.

They say these things must be considered by urban planners in order to find the best solution for each individual city, with a balance needed between performance, cost and viability.

"While urban greening may not be a panacea, our results show what's possible in designing the cities of the future," Dr Cuthbert concluded.

Read more at Science Daily

Lead lurking in your soil? New Chicago project maps distribution

Lead exposure in early childhood can have lifelong consequences, including brain damage, developmental delays, and learning and behavioral disorders. Preventing these devastating outcomes means avoiding lead, but that's only possible if you know where to find it.

Lead haunts old homes in chipping paint and pipes, but it also lurks outside, in soil. It's the stuff of mud pies and garden plots, crumbling from boot treads to join household dust in forgotten corners. It's easily overlooked, but soil can be an important source of lead where children live and play.

A new soil sampling endeavor from the University of Illinois and Illinois Extension reveals elevated lead in parkways and backyards across Chicago. According to the study, every single sample measured lead above the naturally occurring level of 20 parts per million (ppm). And the median value across the city's parkways was 11 times that amount: 220 ppm.

"The previous soil lead assessment of Chicago took only 57 samples, so we went up by orders of magnitude," says Andrew Margenot, assistant professor in the Department of Crop Sciences at U of I and lead author on the study. "But we found the same result overall -- approximately 10 times enrichment above naturally occurring soil lead levels."

The U.S. Environmental Protection Agency sets the maximum threshold for soil lead at 400 ppm for bare soil where children play, and Illinois uses the same standard. Other states, such as California and Minnesota, set the threshold far more conservatively at 80 and 100 ppm, respectively.

In Chicago, 93% of soil samples came in above 80 ppm. But, using the federal and Illinois EPA standard, 94% of the samples were below the threshold of 400 ppm.

"We're in this weird gray area, where depending on what government guidelines you follow, you're either OK or you're not for most of the city," Margenot says. "Frankly, though, I was surprised our mean values weren't higher. Individual backyards in this study measured as high as 3,000 ppm and many U.S. cities have hotspots far exceeding that. So it could have been a lot worse."

Still, Margenot favors California's more conservative standard, citing a 2015 analysis linking soil lead exposure with child blood lead levels and IQ. He notes, however, that soil lead doesn't always translate neatly into blood lead levels. Bioavailability depends on a lot of factors, including soil clay content and organic matter and, more practically, whether soil is bare or covered with turf or cement.

The team found lead unevenly distributed across Chicago's metro area. Broadly speaking, lead levels fell off in concentric rings around the city center, known as the Loop. But localized hotspots threw off what could otherwise have been a tidy correlation between lead levels and distance from the Loop.

"It was in the south, especially the southeast shore, where we found the highest amount. We also detected higher-lead pockets to the west, where you find Garfield Park, and then also going up north where you typically find higher-income areas," Margenot says. "The pattern reflects the historical nature of lead contamination, back when lead paint and leaded gas were used. More houses, more car traffic, more lead was put down in these areas.

"There's a strong environmental justice reality here," he adds. "Under-resourced communities, especially African Americans in Chicago, are disproportionately affected by these contaminants. Redlining policies forced Black Americans into the parts of cities that were typically the worst polluted. This problem is not going away. City leaders and society as a whole need to be willing to invest in monitoring and mitigation efforts to remedy the situation."

Chicago citizens can check their general area against Margenot's map, but despite his team's high-density sampling efforts, the map can't pinpoint lead levels for an individual address. He's working with the Chicago Urban Agriculture Mapping Project to add soil lead to their interactive map, and the data has already been integrated into MapMyEnvironment, an open-source database to visualize environmental hazards. For now, Margenot says people should get their soil tested if they live in high-lead neighborhoods before gardening or sending the kids out to play.

Some parts of the city, specifically near both local airports -- O'Hare and Midway -- were surprisingly low in lead.

"Leaded gasoline is still used in airplane fuel -- small engines like Cessnas -- but not jet fuel. A lot of stakeholders we talked to thought the airports must be full of pollutants, but they were fine with respect to lead. So that's good news," Margenot says.

Although the research team focused on lead in this study, they analyzed a subset of samples for other heavy metals including mercury, cadmium, and arsenic. Margenot says these metals didn't co-occur with lead.

That's not necessarily a good thing.

"In some cities where the source of contaminants is the same, like a smelting operation, all the nasty things are co-deposited together. So if you measure lead, one of the easier heavy metals to measure, you know there's a risk for all the other metals. That's not the case here, which speaks to the diverse sources of metal contaminants in Chicago," he says. "That's an unfortunate finding. It means just because you have low lead doesn't mean you have low arsenic or cadmium, which can be enriched in these soils."

The sampling effort provides a blueprint for other cities interested in mapping soil lead contamination. Margenot's team collected nearly 1,000 soil samples from parkways, that strip between sidewalks and roadways often zoned as public land. Another 156 were collected by citizen scientists from backyards across the city. Although the sample sizes differed significantly, statistical comparisons showed the two types of soils could produce city-wide maps of lead with very similar patterns and levels.

"In backyards, we think most lead is coming from leaded paint, versus roadways where lead is most likely a remnant from leaded gasoline. But the two types of samples gave us a similar distribution of lead across the city. That's good, because if you have to go door to door knocking, it takes longer to develop city-wide assessments." Margenot says.

Read more at Science Daily

Stem cell discoveries hold potential to improve cancer treatment

Two recent discoveries by stem cell scientists at Cedars-Sinai may help make cancer treatment more efficient and shorten the time it takes for people to recover from radiation and chemotherapy.

In the first study, published in the journal Blood, investigators discovered a protein that is expressed by blood stem cells that could aid in identifying, studying and deploying the cells for treatments.

"We show that this protein, syndecan-2, identifies primitive blood stem cells and it regulates stem cell function," said John Chute, MD, director of the Division of Hematology and Cellular Therapy at Cedars-Sinai and senior author of the study.

Blood stem cells are found in small quantities in the bone marrow and in peripheral blood -- the type that travels through the heart, arteries, capillaries and veins. These stem cells are of interest to scientists because they produce all blood cells and immune cells in the body. They are used in the curative treatment of people with leukemia and lymphoma.

This approach faces a major challenge: Hematopoietic stem cells make up less than 0.01% of cells in the bone marrow and peripheral blood, and there is not yet a good way to separate them from other cells. This means that when people receive infusions of bone marrow and peripheral blood cells, they get a tiny number of stem cells that are therapeutic along with a lot of other cells that are not.

To study this phenomenon, investigators at the Chute laboratory led by first author Christina M. Termini, PhD, extracted bone marrow cells from adult mice and ran the samples through a device that can detect hundreds of different types of cells based on the proteins that live on their surfaces.This process revealed that hematopoietic stem cells have a high concentration of syndecan-2, which is part of a family of proteins called heparan sulfate proteoglycans, on the cell surface.

The researchers found this protein plays an important role in how hematopoietic stem cells reproduce. When stem cells that express syndecan-2 were transplanted into mice following irradiation, their cells repopulated. But when stem cells that lacked syndecan-2 were transplanted, the cells stopped replicating.

By transplanting only cells that express syndecan-2, it may be possible to make blood stem cell transplants more efficient and less toxic.

Second Discovery

The second discovery by Chute and his team -- published in the journal Nature Communications -- revealed a mechanism through which the blood vessels in the bone marrow respond to injury, such as from chemotherapy or radiation.

When people receive radiation or chemotherapy as part of their cancer treatment, their blood counts plummet. It typically takes several weeks for these counts to return to normal levels.

Chute and colleages found that when mice receive radiation treatment, the cells that line the inner walls of the blood vessels in the bone marrow produce a protein called semaphorin 3A. This protein tells another protein, called neuropilin 1, to kill damaged blood vessels in the bone marrow.

When the investigators blocked the ability of these blood vessel cells to produce neuropilin 1 or semaphorin 3A, or injected an antibody that blocks semaphorin 3A communication with neuropilin 1, the bone marrow vasculature regenerated following irradiation. In addition, blood counts increased dramatically after one week.

"We've discovered a mechanism that appears to control how blood vessels regenerate following injury," said Chute, senior author of the paper. "Inhibiting this mechanism causes rapid recovery of the blood vessels and blood cells in bone marrow following chemotherapy or irradiation. In principle, targeting this mechanism could allow patients to recover following chemotherapy in one to two weeks, instead of three or four weeks as currently experienced."

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Liquid water beneath Martian south polar cap?

A Southwest Research Institute scientist measured the properties of ice-brine mixtures as cold as -145 degrees Fahrenheit to help confirm that salty water likely exists between grains of ice or sediment under the ice cap at Mars' south pole. Laboratory measurements conducted by SwRI geophysicist Dr. David Stillman support oddly bright reflections detected by the MARSIS subsurface sounding radar aboard ESA's Mars Express orbiter.

With a 130-foot antenna, MARSIS flies over the planet, bouncing radio waves over a selected area and then receiving and analyzing the echoes or reflections. Any near-surface liquid water should send a strong bright signal, whereas the radar signal for ice and rock would be much smaller.

Because conventional models assume the Mars south polar cap experiences temperatures much lower than the melting point of water, many scientists have questioned the presence of liquid water. Clay, hydrated salts and saline ices have been proposed as potential explanations for the source of the bright basal reflections. The Italian-led team investigating the proposed phenomena used previously published data, simulations and new laboratory measurements.

"Lakes of liquid water actually exist beneath glaciers in Arctic and Antarctic regions, so we have Earth analogs for finding liquid water below ice," said Stillman, a specialist in detecting water in any format -- liquid, ice or absorbed -- on planetary bodies and co-author of a paper describing these findings. "The exotic salts that we know exist on Mars have amazing 'antifreeze' properties allowing brines to remain liquid down to -103 degrees Fahrenheit. We studied these salts in our lab to understand how they would respond to radar."

Stillman has over a decade of experience measuring the properties of materials at cold temperatures to detect and characterize subsurface ice, unfrozen water and the potential for life throughout the solar system. For this project, Stillman measured the properties of perchlorate brines in an SwRI environmental chamber that produces near-liquid-nitrogen temperatures at Mars-like pressures.

"My Italian colleagues reached out to see if my laboratory experiment data would support the presence of liquid water beneath the Martian ice cap," Stillman said. "The research showed that we don't have to have lakes of perchlorate and chloride brines, but that these brines could exist between the grains of ice or sediments and are enough to exhibit a strong dielectric response. This is similar to how seawater saturates grains of sand at the shoreline or how flavoring permeates a slushie, but at -103 degrees Fahrenheit below a mile of ice near the South Pole of Mars."

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Researchers provide insight into how the brain multitasks while walking

New research turns the old idiom about not being able to walk and chew gum on its head. Scientists with the Del Monte Institute for Neuroscience at the University of Rochester have shown that the healthy brain is able to multitask while walking without sacrificing how either activity is accomplished.

"This research shows us that the brain is flexible and can take on additional burdens," said David Richardson, an MD/PhD student in his fifth year in the Pathology & Cell Biology of Disease Program, and first author of the study recently published in the journal NeuroImage. "Our findings showed that the walking patterns of the participants improved when they performed a cognitive task at the same time, suggesting they were actually more stable while walking and performing the task than when they were solely focused on walking."

During these experiments, researchers used a Mobile Brain/Body Imaging system, or MoBI, located in the Del Monte Institute's Frederick J. and Marion A. Schindler Cognitive Neurophysiology Lab. The platform combines virtual reality, brain monitoring, and motion capture technology. While participants walk on a treadmill or manipulate objects on a table, 16 high speed cameras record the position markers with millimeter precision, while simultaneously measuring their brain activity.

The MoBI was used to record the brain activity of participants as they walked on a treadmill and were cued to switch tasks. Their brain activity was also recorded as they performed these same tasks while sitting. Brain changes were measured between the cued tasks and showed that during the more difficult the tasks the neurophysiological difference was greater between walking and sitting -- highlighting the flexibility of a healthy brain and how it prepares for and executes tasks based on difficulty level.

"The MoBI allows us to better understand how the brain functions in everyday life," said Edward Freedman, Ph.D., lead author on the study. "Looking at these findings to understand how a young healthy brain is able to switch tasks will give us better insight to what's going awry in a brain with a neurodegenerative disease like Alzheimer's disease."

"Understanding how a young healthy brain can successfully 'walk and talk' is an important start, but we also need to understand how these findings differ in the brains of healthy older adults, and adults with neurodegenerative diseases," said Richardson. "The next stage is expanding this research to include a more diverse group of brains."

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Redefining alcohol use disorder

Researchers at the University of Missouri have developed a new framework that they believe will help identify people previously overlooked for alcohol use disorder (AUD). This framework focuses on 13 risk factors, such as impulsive behavior, reward sensitivity, and punishment sensitivity, that could lead to someone developing an AUD.

"We know from decades of research that there are a lot of different pathways to alcohol use disorder," said Cassie Boness, a former graduate student at MU in the Department of Psychological Sciences. "So, we want to make sure that we are targeting people's specific pathways as accurately as possible in order to be most effective in identifying and treating AUD."

Throughout her career, Boness has been interested in the causes, diagnosis and assessment of substance use disorders, including AUD, a chronic medical condition characterized by ongoing alcohol use despite adverse consequences. For Boness, it's personal -- after seeing her loved ones stigmatized for their addiction to alcohol, and then watching them struggle to get connected with treatment, she wanted to help reduce the amount of suffering people may experience with AUD.

While today's assessment tools, such as the Diagnostic and Statistical Manual of Mental Disorders, Fifth Edition (DSM-5) can help health care professionals diagnose someone with AUD, Boness believes the current methods are too narrowly focused on the consequences of someone's actions, rather than incorporating a broad list of potential risk factors that may lead to an AUD diagnosis.

Boness, who is now a research assistant professor at the University of New Mexico, hopes their framework can be a step forward toward a comprehensive diagnosis of AUD throughout the health care community. However, she stresses that this tool is not meant to be the only solution, but rather a way for other researchers like her to build upon and enhance the existing research on the subject.

"Eventually, we'd like to see assessment tools that more comprehensively capture the factors articulated in our framework so that we can identify individual profiles of risk and potentially intervene during earlier stages of addiction," Boness said.

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Using the eye as a window into heart disease

Scientists have developed an artificial intelligence (AI) system that can analyse eye scans taken during a routine visit to an optician or eye clinic and identify patients at a high risk of a heart attack.

Doctors have recognised that changes to the tiny blood vessels in the retina are indicators of broader vascular disease, including problems with the heart.

In the research, led by the University of Leeds, deep learning techniques were used to train the AI system to automatically read retinal scans and identify those people who, over the following year, were likely to have a heart attack.

Deep learning is a complex series of algorithms that enable computers to identify patterns in data and to make predictions.

Writing in the journal Nature Machine Intelligence, the researchers report that the AI system had an accuracy of between 70% and 80% and could be used as a second referral mechanism for in-depth cardiovascular investigation.

The use of deep learning in the analysis of retinal scans could revolutionise the way patients are regularly screened for signs of heart disease.

Professor Alex Frangi, who holds the Diamond Jubilee Chair in Computational Medicine at the University of Leeds and is a Turing Fellow at the Alan Turing Institute, supervised the research. He said: "Cardiovascular diseases, including heart attacks, are the leading cause of early death worldwide and the second-largest killer in the UK. This causes chronic ill-health and misery worldwide.

"This technique opens-up the possibility of revolutionising the screening of cardiac disease. Retinal scans are comparatively cheap and routinely used in many optician practices. As a result of automated screening, patients who are at high risk of becoming ill could be referred to specialist cardiac services.

"The scans could also be used to track the early signs of heart disease."

The study involved a worldwide collaboration of scientists, engineers and clinicians from the University of Leeds; Leeds Teaching Hospitals' NHS Trust; the University of York; the Cixi Institute of Biomedical Imaging in Ningbo, part of the Chinese Academy of Sciences; the University of Cote d'Azur, France; the National Centre for Biotechnology Information and the National Eye Institute, both part of the National Institutes for Health in the US; and KU Leuven in Belgium.

The UK Biobank provided data for the study.

Chris Gale, Professor of Cardiovascular Medicine at the University of Leeds and a Consultant Cardiologist at Leeds Teaching Hospitals NHS Trust, was one of the authors of the research paper.

He said: "The AI system has the potential to identify individuals attending routine eye screening who are at higher future risk of cardiovascular disease, whereby preventative treatments could be started earlier to prevent premature cardiovascular disease."

Deep learning

During the deep learning process, the AI system analysed the retinal scans and cardiac scans from more than 5,000 people. The AI system identified associations between pathology in the retina and changes in the patient's heart.

Once the image patterns were learned, the AI system could estimate the size and pumping efficiency of the left ventricle, one of the heart's four chambers, from retinal scans alone. An enlarged ventricle is linked with an increased risk of heart disease.

With information on the estimated size of the left ventricle and its pumping efficiency combined with basic demographic data about the patient, their age and sex, the AI system could make a prediction about their risk of a heart attack over the subsequent 12 months.

Currently, details about the size and pumping efficiency of a patient's left ventricle can only be determined if they have diagnostic tests such as echocardiography or magnetic resonance imaging of the heart. Those diagnostic tests can be expensive and are often only available in a hospital setting, making them inaccessible for people in countries with less well-resourced healthcare systems -- or unnecessarily increasing healthcare costs and waiting times in developed countries.

Read more at Science Daily

Tug of sun, moon could be driving plate motions on ‘imbalanced’ Earth

A study led by geophysicist Anne M. Hofmeister in Arts & Sciences at Washington University in St. Louis proposes that imbalanced forces and torques in the Earth-moon-sun system drive circulation of the whole mantle.

The new analysis provides an alternative to the hypothesis that the movement of tectonic plates is related to convection currents in the Earth's mantle. Convection involves buoyant rise of heated fluids, which Hofmeister and her colleagues argue does not apply to solid rocks. They argue that force, not heat, moves large objects. The new research is published in a special paper of the Geological Society of America, as part of a forthcoming collection assembled in honor of geologist Warren B. Hamilton.

Earth's internal workings are popularly modeled as dissipating heat generated by internal radioactivity and from leftover energy created during collisions when our planet formed. But even mantle convection proponents recognize that that amount of internal heat-energy is insufficient to drive large-scale tectonics. And there are other problems with using convection to explain observed plate motions.

Instead, Earth's plates might be shifting because the sun exerts such a strong gravitational pull on the moon that it has caused the moon's orbit around Earth to become elongated.

Over time, the position of the barycenter -- the center of mass between the orbiting bodies of the Earth and the moon -- has moved closer to Earth's surface and now oscillates 600 km per month relative to the geocenter, Hofmeister said. This sets up internal stresses, as the Earth continues to spin.

"Because the oscillating barycenter lies ~4600 km from the geocenter, Earth's tangential orbital acceleration and solar pull are imbalanced except at the barycenter," Hofmeister said. "The planet's warm, thick and strong interior layers can withstand these stresses, but its thin, cold, brittle lithosphere responds by fracturing."

Daily spin flattens the Earth from a perfect spherical shape, which contributes to this brittle failure of the lithosphere. These two independent stresses create the mosaic of plates observed in the outer shell, the authors suggest. The variety of plate motions comes from the changes in size and direction of the imbalanced gravitational forces with time.

But how to test this alternative? Hofmeister suggested: "One test would be a detailed examination of the tectonics of Pluto, which is too small and cold to convect, but has a giant moon and a surprisingly young surface."

The study includes a comparison of rocky planets that shows that the presence and longevity of volcanism and tectonism depend on the particular combination of moon size, moon orbital orientation, proximity to the sun and rates of body spin and cooling.

Earth is the only rocky planet with all the factors needed for plate tectonics, Hofmeister noted.

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Scientists identify new genus and species of legume, now mysteriously extinct

Oregon State University researchers have described a new legume tree from flowers embedded in several lumps of amber recovered from deep within an amber mine in the mountains of the Dominican Republic.

OSU's George Poinar Jr. and Kenton Chambers placed the 20- to 30-million-year-old flowers in a novel genus and species, Salpinganthium hispaniolanum, in the family Fabaceae.

"The flowers are quite striking with their spreading sepals and petals, along with the 10 extended stamens," said Poinar, an international expert in using plant and animal life forms preserved in amber to learn about the biology and ecology of the distant past. "While now darkened with age, the petals were probably white, yellow or even pink, which are the petal colors of the closely related purpleheart tree, whose strong, durable, purplish wood is prized by artists, ship builders, furniture makers and other crafts people."

Groves of purpleheart trees continue to grow along rivers in tropical rain forests in Central and South America, particularly in the Amazon basin, said Poinar, professor emeritus in the Oregon State College of Science.

Poinar and Chambers, professor emeritus in the OSU College of Agricultural Sciences, derived the name of the genus from the Greek words for tube, trumpet and flower. The species name is based on the Caribbean island, Hispaniola, where the fossil originated.

"While purpleheart trees are still with us, Salpinganthium trees have disappeared," said Poinar. "We can only speculate about why these fossil trees have become extinct."

They could have succumbed to some unique biological and/or physical events, such as the loss of a pollinator, presence of a pathogen or climatic change that ravaged populations throughout their entire range, Poinar said. Finding their flowers in five separate pieces of amber shows that they were well established in the Dominican amber forest, he added.

Poinar and Chambers placed Salpinganthium hispaniolanum, the latest in a number of flowers described by the authors from Dominican amber mines, in the resin-producing tribe Detarieae; the tribe's members have sepals and petals dotted with glands.

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Transparency in butterflies, from A-Z: It’s more of a superpower than we thought

Like invisibility in legends, transparency in nature is a powerful tool. Most transparent animals live in the ocean, where a close visual match with the water renders them almost invisible to predators.

On land, transparency is rare and difficult to achieve, but some butterflies and moths (Lepidoptera) do have transparent wings. And a new study indicates transparency can serve not only to camouflage them, but in other cases to signal and warn predators, "Don't eat me! I'm toxic."

This flexible weapon for self-defense is one of many findings from a multiyear study spanning the physics, biology, ecology, and evolution of transparency in Lepidoptera conducted by several groups, including the lab of Nipam Patel, director of the Marine Biological Laboratory (MBL).

"This is one of those interdisciplinary studies you dream about, where you want to understand [a biological structure] from its physics to its development and ecology," says Patel of the international study, which began as a project in the MBL Embryology course and ended up being funded by the Human Frontier Science Program. Ph.D. candidate Aaron Pomerantz in Patel's lab is also on the team.

Mimicry for Self-Defense

The group's latest paper adds a unique perspective on Lepidoptera self-defense. In some species, vivid wing coloration indicates the presence of chemical defenses that make the butterfly unpalatable or toxic, and predators learn to avoid them. Accordingly, palatable species can evolve to mimic the toxic ones, so predators leave them alone, too. In addition, multiple unpalatable species may converge in their warning colorations, thereby sharing in the benefits of the warning coloration process. Large "mimicry rings" can even form containing both toxic and nontoxic species, all displaying strikingly similar patterns and color combinations.

"The most amazing place to see this is the Amazon," Patel says. "You'll find a group of species that are distantly related to each other, yet they've all converged on a similar wing pattern."

Surprisingly, mimicry rings have also been found among clear-wing species in the Amazon. "So we asked, 'Wait, why would a species be transparent and unpalatable at the same time?'" Patel says. And, structurally, how would a clear-wing species accomplish that trick?

The team looked at the optical and structural properties of transparent butterfly wings within mimicry rings to see if they were convergent, and found in some rings, they were.

"In one transparency ring we studied (see photo 1, middle row), the key unpalatable butterfly doesn't have an anti-glare coating on its transparent wing, so in sunlight, it's really easy to see," Patel says. "It may be signaling a warning pattern to predators when it's in bright sun, and it's camouflaged when in shadows. So it kind of cheats: it has the best of both worlds."

Previously, the team reported on the developmental origins of transparency in a clear-wing species, Greta oto. They also compared wing transparency across 123 Lepidoptera species for its structural basis, optical properties, and biological relevance in relation to concealment, thermoregulation, and protection against UV. Those results showed a wide diversity of solutions to achieve transparency, suggesting that transparency has likely evolved multiple times independently.

Approaching transparency from multiple disciplines brought emergent knowledge and interesting new questions, Patel said. "Now that we've identified different Lepidoptera groups that have found different ways to achieve transparency, we can ask, how did they actually do this? Or, alternatively, if two very distant lineages have come up with the same solution for transparency, did they solve the problem in the same way?"

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My heart will go on: Patient-derived heart cells mimic disease in vitro

How can you mend a broken heart? According to researchers from Japan, in some cases gene replacement therapy just might do the trick.

In a study published in January in Stem Cell Reports, researchers from Osaka University report that heart cells from a patient with an inherited heart disease called arrhythmogenic cardiomyopathy do not contract correctly when grown in the laboratory, and that replacing the mutated gene responsible for this effect fixes this defect.

Arrhythmogenic cardiomyopathy occurs due to mutations in genes involved in desmosomes, which form 'welds' between cells that help them communicate and move in a coordinated way. One of these genes, PKP2, encodes a protein known as plakophilin-2 that is crucial to maintaining heart cell structure.

"Previous studies carried out in cardiomyocytes have shown that mutations in PKP2 play a pathological role in arrhythmogenic cardiomyopathy," says lead author of the study Hiroyuki Inoue. "However, the cells used in those experiments were derived from healthy individuals and were not assessed for contractile function."

To investigate how cells derived from patients behave in the laboratory, the researchers first took a blood sample from a young patient with arrhythmogenic cardiomyopathy, induced some of the blood cells to become stem cells, and then differentiated these stem cells into heart cells. They then modified this original batch of heart cells into three different cell lines with precisely adjusted PKP2 expression based on how many mutated or intact copies of the gene were present.

"The cells with two mutated copies of PKP2 clearly exhibited reduced contractility and impaired desmosome assembly due to plakophilin-2 deficiency," explains Shuichiro Higo, senior author. "These effects were also observed in cells with only one mutated copy of PKP2, although they were less severe."

Replacing the mutated PKP2 with an intact copy of the gene repaired the defects in both cell contraction and desmosome assembly, which the researchers were able to observe using a time-lapse approach and fluorescently labeled desmosomes.

"These findings suggest that our cardiomyocyte cell lines recapitulate the pathology of arrhythmogenic cardiomyopathy and provide a rapid and convenient platform for developing gene-based therapies for this disease," says Higo.

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Sidewinding young stellar jets spied by Gemini South

Sinuous stellar jets meander lazily across a field of stars in new images captured from Chile by the international Gemini Observatory, a Program of NSF's NOIRLab. The gently curving stellar jets are the outflow from young stars, and astronomers suspect their sidewinding appearances are caused by the gravitational attraction of companion stars. These crystal-clear observations were made using the Gemini South telescope's adaptive optics system, which helps astronomers counteract the blurring effects of atmospheric turbulence.

Young stellar jets are a common by-product of star formation and are thought to be caused by the interplay between the magnetic fields of rotating young stars and the disks of gas surrounding them. These interactions eject twin torrents of ionized gas in opposite directions, such as those pictured in two images captured by astronomers using the Gemini South telescope on Cerro Pachón on the edge of the Chilean Andes. Gemini South is one half of the international Gemini Observatory, a Program of NSF's NOIRLab, that comprises twin 8.1-meter optical/infrared telescopes on two of the best observing sites on the planet. Its counterpart, Gemini North, is located near the summit of Maunakea in Hawai'i.

The jet in the first image, named MHO 2147, is roughly 10,000 light-years from Earth, and lies in the galactic plane of the Milky Way, close to the boundary between the constellations Sagittarius and Ophiuchus. MHO 2147 snakes across a starry backdrop in the image -- an appropriately serpentine appearance for an object close to Ophiuchus. Like many of the 88 modern astronomical constellations, Ophiuchus has mythological roots -- in ancient Greece it represented a variety of gods and heroes grappling with a serpent. MHO 1502, the jet pictured in the second image, is located in the constellation of Vela, approximately 2000 light-years away.

Most stellar jets are straight but some can be wandering or knotted. The shape of the uneven jets is thought to be related to a characteristic of the object or objects that created them. In the case of the two bipolar jets MHO 2147 and MHO 1502, the stars which created them are obscured from view.

In the case of MHO 2147, this young central star, which has the catchy identifier IRAS 17527-2439, is embedded in an infrared dark cloud -- a cold, dense region of gas that is opaque at the infrared wavelengths represented in this image. The sinuous shape of MHO 2147 is caused because the direction of the jet has changed over time, tracing out a gentle curve on either side of the central star. These almost unbroken curves suggest that MHO 2147 has been sculpted by continuous emission from its central source. Astronomers found that the changing direction (precession) of the jet may be due to the gravitational influence of nearby stars acting on the central star. Their observations suggest that IRAS 17527-2439 could belong to a triple star system separated by more than 300 billion kilometers (almost 200 billion miles).

MHO 1502, on the other hand, is embedded in a totally different environment -- an area of star formation known as an HII region. The bipolar jet is composed of a chain of knots, suggesting that its source, thought to be two stars, has been intermittently emitting material.

These detailed images were captured by the Gemini South Adaptive Optics Imager (GSAOI), an instrument on the 8.1-meter-diameter Gemini South telescope. Gemini South is perched on the summit of Cerro Pachón, where dry air and negligible cloud cover provide one of the best observing sites on the planet. Even atop Cerro Pachón, however, atmospheric turbulence causes the stars to blur and twinkle.

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In visual memory, size matters

Every day we encounter images on the wall, in newspapers, books, and electronic devices. Some become etched in our memory and some don't. The elements influencing whether we remember one image and not the other aren't yet known, but researchers have assumed that image size and memory aren't connected to one another, since we usually understand what appears in an image, whether it is large or small.

A new study led by Dr. Sharon Gilaie-Dotan, of Bar-Ilan University's School of Optometry and Vision Science and Gonda (Goldschmied) Multidisciplinary Brain Research Center, sought to determine whether large images are better remembered than small ones during natural daily behavior. Her assumption was based on the fact that large images require the visual system to utilize greater resources for processing them.

The results of the study, just published in the journal Proceedings of the National Academy of Sciences, show for the first time that in natural vision, visual memory of images is affected by the size of the image on the retina. These findings can have many implications, including on the use of different types of electronic screens and the quality of information processing when we rely on large vs. small screens.

Shaimaa Masarwa and Olga Kreichman, PhD students in Dr. Gilaie-Dotan's lab, examined what happens to visual memory when participants were asked to look at pictures without knowing anything about a memory task to come. Each participant was shown different pictures in different sizes, each presented to them just once.

One hundred eighty-two subjects participated in seven different experiments. Time and time again the researchers found that the large images were better remembered (1.5 times more) than the small images. This phenomenon was not dependent on specific stimuli, the order in which the images appeared, their resolution, or the amount of information they contained.

To understand whether this result was determined by size rather than amount of detail, the researchers also examined whether large, blurred images are better etched in memory than clear, small images, where the large images contained the same details as the small images. To their surprise, they found that even in this case, the participants remembered the large, blurry images better than the small, clear images.

They also found that most images were better remembered when they were presented as bigger relative to when they were presented as smaller.

"In areas of the brain that represent the retinal image, more resources will be directed to processing large images than to processing small images because the processing is determined by the area of the retina that the image stimulates," says Dr. Gilaie-Dotan. She points out that additional factors may contribute to remembering large images, such as different eye movements, and more attention and interest that large images elicit.

The study was conducted on young adults aged 18-40, ages in which vision is completely developed but has not yet begun to age. Different ages may be affected by the size of the stimuli in a different way, since both age and experience with screens are quite different between young and old.

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