In a new quantum simulator, light behaves like a magnet

Riccardo Rota and Vincenzo Savona, the two EPFL physicists leading the study, working on the design of their quantum simulator.

When subject to the laws of quantum mechanics, systems made of many interacting particles can display behaviour so complex that its quantitative description defies the capabilities of the most powerful computers in the world. In 1981, the visionary physicist Richard Feynman argued we can simulate such complex behavior using an artificial apparatus governed by the very same quantum laws -- what has come to be known as a "quantum simulator."

One example of a complex quantum system is that of magnets placed at really low temperatures. Close to absolute zero (-273.15 degrees Celsius), magnetic materials may undergo what is known as a "quantum phase transition." Like a conventional phase transition (e.g. ice melting into water, or water evaporating into steam), the system still switches between two states, except that close to the transition point the system manifests quantum entanglement -- the most profound feature predicted by quantum mechanics. Studying this phenomenon in real materials is an astoundingly challenging task for experimental physicists.

But physicists led by Vincenzo Savona at EPFL have now come up with a quantum simulator that promises to solve the problem. "The simulator is a simple photonic device that can easily be built and run with current experimental techniques," says Riccardo Rota, the postdoc at Savona's lab who led the study. "But more importantly, it can simulate the complex behavior of real, interacting magnets at very low temperatures."

The simulator may be built using superconducting circuits -- the same technological platform used in modern quantum computers. The circuits are coupled to laser fields in such a way that it causes an effective interaction among light particles (photons). "When we studied the simulator, we found that the photons behaved in the same way as magnetic dipoles across the quantum phase transition in real materials," says Rota. In short, we can now use photons to run a virtual experiment on quantum magnets instead of having to set up the experiment itself.

"We are theorists," says Savona. "We came up with the idea for this particular quantum simulator and modelled its behavior using traditional computer simulations, which can be done when the quantum simulator addresses a small enough system. Our findings prove that the quantum simulator we propose is viable, and we are now in talks with experimental groups who would like to actually build and use it."

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Paleontologists report world's biggest Tyrannosaurus rex

The towering and battle-scarred 'Scotty' reported by UAlberta paleontologists is the world's largest Tyrannosaurus rex and the largest dinosaur skeleton ever found in Canada.

University of Alberta paleontologists have just reported the world's biggest Tyrannosaurus rex and the largest dinosaur skeleton ever found in Canada. The 13-metre-long T. rex, nicknamed "Scotty," lived in prehistoric Saskatchewan 66 million years ago.

"This is the rex of rexes," said Scott Persons, lead author of the study and postdoctoral researcher in the Department of Biological Sciences. "There is considerable size variability among Tyrannosaurus. Some individuals were lankier than others and some were more robust. Scotty exemplifies the robust. Take careful measurements of its legs, hips, and even shoulder, and Scotty comes out a bit heftier than other T. rex specimens."

Scotty, nicknamed for a celebratory bottle of scotch the night it was discovered, has leg bones suggesting a living weight of more than 8,800 kg, making it bigger than all other carnivorous dinosaurs. The scientific work on Scotty has been a correspondingly massive project.

The skeleton was first discovered in 1991, when paleontologists including T. rex expert and UAlberta professor Phil Currie were called in on the project. But the hard sandstone that encased the bones took more than a decade to remove -- only now have scientists been able to study Scotty fully-assembled and realize how unique a dinosaur it is.

It is not just Scotty's size and weight that set it apart. The Canadian mega rex also lays claim to seniority.

"Scotty is the oldest T. rex known," Persons explains. "By which I mean, it would have had the most candles on its last birthday cake. You can get an idea of how old a dinosaur is by cutting into its bones and studying its growth patterns. Scotty is all old growth."

But age is relative, and T. rexes grew fast and died young. Scotty was estimated to have only been in its early 30s when it died.

"By Tyrannosaurus standards, it had an unusually long life. And it was a violent one," Persons said. "Riddled across the skeleton are pathologies -- spots where scarred bone records large injuries."

Among Scotty's injures are broken ribs, an infected jaw, and what may be a bite from another T. rex on its tail -- battle scars from a long life.

"I think there will always be bigger discoveries to be made," said Persons "But as of right now, this particular Tyrannosaurus is the largest terrestrial predator known to science."

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Climate change affecting fish in Ontario lakes

Warmer temperatures are having a ripple effect on food webs in Ontario lakes, according to a new University of Guelph study.

Researchers have found warmer average temperatures over the past decade have forced fish to forage in deeper water. There they hunt different prey species, causing a climate-induced "rewiring" of food webs, altering the flow of energy and nutrients in the lake.

Monitoring the movement of generalist species like lake trout may offer an early warning system for impacts of climate change on ecosystems.

"We can harness the natural capacity of species to detect and respond to changes in their environment," said Tim Bartley, a post-doc in the Department of Integrative Biology and study lead author. "As species are changing their behaviour, they are telling us about what's happening around them in their environment. We can use this information. The behavioural changes we see imply major reorganization of ecosystems."

Published in the journal Nature Ecology and Evolution, the study entailed tracking lake trout movement and feeding in hundreds of lakes in northwestern Ontario.

Bartley caught fish to analyze their tissues to see what they ate. The team also used similar data about fish feeding habits and locations across the province from the Ontario Ministry of Natural Resources.

Tissue analysis showed that lake trout spend more time in deeper water than near shore, although the researchers were unable to identify specific prey species. Lake trout prefer to catch lake herring; Bartley said trout are flexible feeders that will eat other fish species as well as invertebrates.

He said warming may also be pushing lake herring into colder waters, meaning that lake trout may still feed on them in offshore locations.

Monitoring behavioural changes in species such as lake trout is important for humans who rely on ecosystems for resources and services from food to water quality, said Bartley.

Climate change effects are complicated and vary within ecosystems to create a patchwork of new conditions, he said. Other organisms, including lake trout prey, are also moving in response to warming.

Tracking the movement, feeding habits and condition of generalist species such as lake trout may give resource managers an early warning system for detecting the effects of warming.

That's important for managing the entire ecosystem and for looking after populations of lake trout, a popular sport fish for anglers, said Bartley.

But it's not just happening in lakes.

The study also includes data from American researchers showing similar ecosystem "rewiring" in grasslands involving grasshoppers and predatory spiders moving down to cooler areas nearer the soil.

The U of G researchers also point to other studies of climate change effects on rewiring of ecosystems involving beluga whales and halibut in Nunavut, polar bears and ringed seals across the Arctic, and Kodiak bears feeding on elderberries and sockeye salmon on the Pacific coast.

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Blue Brain solves a century-old neuroscience problem

Illustration of morphological types of pyramidal cells within the rodent cortical layer.

New research explains how the shapes of neurons can be classified using mathematical methods from the field of algebraic topology. Neuroscientists can now start building a formal catalogue for all the types of cells in the brain. Onto this catalogue of cells, they can systematically map the function and role in disease of each type of neuron in the brain.

"For nearly 100 years, scientists have been trying to name cells. They have been describing them in the same way that Darwin described animals and trees. Now the Blue Brain Project has developed a mathematical algorithm to objectively classify the shapes of the neurons in the brain," explains Professor Henry Markram, Blue Brain's Founder and Director. "This will allow the development of a standardized taxonomy [classification of cells into distinct groups] of all cells in the brain, which will help researchers compare their data in a more reliable manner."

The team, with lead scientist Lida Kanari, have developed an algorithm to distinguish the different shapes of the most common type of neuron in the neocortex -- the pyramidal cells. Pyramidal cells are distinctively tree-like cells that make up 80% of the neurons in the neocortex and, like antennas, collect information from other neurons in the brain. Basically, they are the redwoods of the forests of trees in the brain. They are excitatory, sending waves of electrical activity through the network, as we perceive, act, and feel.

The father of modern neuroscience, Ramón y Cajal, first drew pyramidal cells over 100 years ago, by looking at them under a microscope. Yet, up until now, scientists have not reached a consensus on the types of pyramidal neurons. Anatomists have been assigning names and debating the different types for the past century, while neuroscience has been unable to tell for sure which types of neurons are subjectively characterized. Even for visibly distinguishable neurons, there is no common ground to consistently define morphological types.

Seventeen types of pyramidal cells

The study from Blue Brain proves for the first time that objective classification of these pyramidal cells is possible, by applying tools from algebraic topology, the branch of mathematics that studies the shape, connectivity, and the emergence of global structure from local constraints.

Blue Brain has pioneered the use of algebraic topology to tackle a wide range of neuroscience problems, and with this study has once again demonstrated its effectiveness. In collaboration with Professors Kathryn Hess at EPFL and Ran Levi from the University of Aberdeen, Blue Brain developed an algorithm, which they then used to objectively classify seventeen types of pyramidal cells in the rat somatosensory cortex. The topological classification does not require expert input, and is proven to be robust.

The structure of most neurons resembles a complex tree, with multiple branches connecting to other neurons and communicating via electrical signals. If we keep the longest (persistent) components of the neuron structure and decompose the smaller branches, we can transform its tree-like structure into a barcode -- a mathematical object that can be used as input for any machine-learning algorithm that will classify the neurons into distinct groups.

"Species" of brain cells

Any neuron classification process is plagued by this question: are two cells that look different just part of a continuum of gradually changing differences (like different "strains" of a species, e.g. different types of dogs) or are they really different "species" of neurons (e.g. dogs, cats, elephants, etc.)? In other words, are they discrete or continuous morphological variations of each other? This can be answered by using the new topological classification and grouping the different "species" of brain cells, each with its own characteristic "strains."

"The Blue Brain Project is digitally reconstructing and simulating the brain, and this research provides one of the solid foundations needed to put all the types of neurons together," explains Kanari. "By removing the ambiguity of cell types, the process of identifying the morphological type of new cells will become fully automated."

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Potential new therapy for liver diseases

Drug therapy may effectively treat a potentially life-threatening condition associated with cirrhosis and other chronic liver diseases, according to a new study by Mayo Clinic researchers. The study was posted in March on Gastroenterology, the online journal of the American Gastroenterological Association. Print publication is scheduled for July.

While therapies have been available to treat some forms of liver disease, including hepatitis C and autoimmune hepatitis, options have been more limited for treating portal hypertension, a condition where there is an increase in pressure within the portal vein that carries blood from abdominal organs to the liver. Portal hypertension is associated with cirrhosis and other chronic liver diseases.

According to the study, the drug sivelestat may effectively lower portal hypertension, improving symptoms and outcomes for those patients. The study results were obtained from mouse models but have since been confirmed in liver samples from humans, according to Vijay Shah, M.D., a Mayo Clinic gastroenterologist and senior author.

"This was an exciting confirmation of our findings and their applicability to human disease," Dr. Shah says. "Sivelestat has been safely used in humans with acute lung injury and bronchopulmonary dysplasia. This suggests that sivelestat and similar drugs constitute a potential means to decrease portal hypertension in patients with chronic liver disease."

The Mayo study showed that deposits of fibrin -- microvascular blood clots -- contributed to portal hypertension, and inflammatory cells known as neutrophils contributed to the formation of fibrin. By inhibiting neutrophil function with sivelestat, they were able to decrease portal hypertension.

"Neutrophils had not previously been identified as significant drivers of portal hypertension," says Moira Hilscher, M.D., the paper's first author. Results were verified in two different models of chronic liver disease.

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Jupiter's unknown journey revealed

Jupiter was formed four times further from the sun than its current position would indicate, according to a new simulation.

It is known that gas giants around other stars are often located very near their sun. According to accepted theory, these gas planets were formed far away and subsequently migrated to an orbit closer to the star.

Now researchers from Lund University and other institutions have used advanced computer simulations to learn more about Jupiter's journey through our own solar system approximately 4.5 billion years ago. At that time, Jupiter was quite recently formed, as were the other planets in the solar system. The planets were gradually built up by cosmic dust, which circled around our young sun in a disk of gas and particles. Jupiter was no larger than our own planet.

The results show that Jupiter was formed four times further from the sun than its current position would indicate.

"This is the first time we have proof that Jupiter was formed a long way from the sun and then migrated to its current orbit. We found evidence of the migration in the Trojan asteroids orbiting close to Jupiter," explains Simona Pirani, doctoral student in astronomy at Lund University, and the lead author of the study.

These Trojan asteroids consist of two groups of thousands of asteroids that reside at the same distance from the Sun as Jupiter, but orbiting in front of and behind Jupiter, respectively. There are approximately 50 per cent more Trojans in front of Jupiter than behind it. It is this asymmetry that became the key to the researchers' understanding of Jupiter's migration.

"The asymmetry has always been a mystery in the solar system," says Anders Johansen, professor of astronomy at Lund University.

Indeed, the research community had previously been unable to explain why the two asteroid groups do not contain the same number of asteroids. However, Simona Pirani and Anders Johansen, together with other colleagues, have now identified the reason by recreating the course of events of Jupiter's formation and how the planet gradually drew in its Trojan asteroids.

Thanks to extensive computer simulations, the researchers have calculated that the current asymmetry could only have occurred if Jupiter was formed four times further out in the solar system and subsequently migrated to its current position. During its journey towards the sun, Jupiter's own gravity then drew in more Trojans in front of it than behind it.

According to the calculations, Jupiter's migration went on for around 700,000 years, in a period approximately 2-3 million years after the celestial body started its life as an ice asteroid far from the sun. The journey inwards in the solar system followed a spiralling course in which Jupiter continued to circle around the sun, albeit in an increasingly tight path. The reason behind the actual migration relates to gravitational forces from the surrounding gases in the solar system.

The simulations show that the Trojan asteroids were drawn in when Jupiter was a young planet with no gas atmosphere, which means that these asteroids most probably consist of building blocks similar to those that formed Jupiter's core. In 2021, NASA's space probe Lucy will be launched into orbit around six of Jupiter's Trojan asteroids to study them.

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World's smallest bears' facial expressions throw doubt on human superiority

Adult female sun bear in Malaysia.

The world's smallest bears can exactly mimic another bear's facial expressions, casting doubt on humans and other primates' supremacy at this subtle form of communication.

It is the first time such exact facial mimicry has been seen outside of humans and gorillas.

The research, by Dr Marina Davila-Ross and PhD candidate Derry Taylor, both at the University of Portsmouth, is published in Scientific Reports.

The researchers studied sun bears -- a solitary species in the wild, but also surprisingly playful -- for more than two years.

They found bears can use facial expressions to communicate with others in a similar way to humans and apes, strongly suggesting other mammals might also be masters of this complex social skill and, in addition, have a degree of social sensitivity.

Dr Davila-Ross said: "Mimicking the facial expressions of others in exact ways is one of the pillars of human communication. Other primates and dogs are known to mimic each other, but only great apes and humans, and now sun bears, were previously known to show such complexity in their facial mimicry.

"Because sun bears appear to have facial communication of such complexity and because they have no special evolutionary link to humans like monkeys are apes, nor are they domesticated animals like dogs, we are confident that this more advanced form of mimicry is present in various other species. This, however, needs to be further investigated.

"What's most surprising is the sun bear is not a social animal. In the wild, it's a relatively solitary animal, so this suggests the ability to communicate via complex facial expressions could be a pervasive trait in mammals, allowing them to navigate their societies."

Facial mimicry is when an animal responds to another's facial expression with the same or similar expression. Mr Taylor coded the facial expressions of 22 sun bears in spontaneous social play sessions.

The bears, aged 2-12, were housed in Bornean Sun Bear Conservation Centre in Malaysia in which enclosures were large enough to allow bears to choose whether to interact or not.

Despite the bears' preference in the wild for a solitary life, the bears in this study took part in hundreds of play bouts, with more than twice as many gentle play sessions compared to rough play.

During these encounters, the research team coded two distinct expressions -- one involving a display of the upper incisor teeth, and one without.

The bears were most likely to show precise facial mimicry during gentle play.

Mr Taylor said such subtle mimicking could be to help two bears signal that they are ready to play more roughly, or to strengthen social bonds.

He said: "It is widely believed that we only find complex forms of communication in species with complex social systems. As sun bears are a largely solitary species, our study of their facial communication questions this belief, because it shows a complex form of facial communication that until now was known only in more social species.

"Sun bears are an elusive species in the wild and so very little is known about them. We know they live in tropical rainforests, eat almost everything, and that outside of the mating season adults have little to do with one another.

"That's what makes these results so fascinating -- they are a non-social species who when face to face can communicate subtly and precisely."

Sun bears, also known as honey bears, stand at 120-150 cm tall and weigh up to 80kg. They are endangered and live in the tropical forests of south-east Asia.

Social sophistication aside, sun bear numbers are dwindling due to deforestation, poaching and being killed by farmers for eating crops. Increasingly, new mother bears are killed so their cub can be taken and raised as a pet or kept in captivity as 'bile bears' where their bile is harvested for use in some Chinese medicines.

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Ancient birds out of the egg running

Feathers revealed in a ~125 million-year-old fossil of a bird hatchling shows it came "out of the egg running". Specimen MPCM-LH-26189 from Los Hoyas, Spain is preserved between two slabs of rock: (a) 'counter' slab under normal light (b) Laser-Stimulated Fluorescence (LSF) image combining the results from both rock slabs. This reveals brown patches around the specimen that include clumps of elongate feathers associated with the neck and wings and a single long vaned feather associated with the left wing. (c) Normal light image of the main slab. Scale is 5mm.

The ~125 million-year-old Early Cretaceous fossil beds of Los Hoyas, Spain have long been known for producing thousands of petrified fish and reptiles. However, one special fossil stands unique and is one of the rarest of fossils -- a nearly complete skeleton of a hatchling bird. Using their own laser imaging technology, Dr Michael Pittman from the Department of Earth Sciences at The University of Hong Kong and Thomas G Kaye from the Foundation for Scientific Advancement in the USA determined the lifestyle of this ~3cm long hatchling bird by revealing the previously unknown feathering preserved in the fossil specimen.

Chickens and ducks are up and about within hours of hatching, they are "precocial." Pigeons and eagles are "altricial," they stay in the nest and are looked after by their parents. How do you tell if a hatchling came "out of the egg running" or was "naked and helpless in the nest"? Feathers. When precocial birds hatch they have developed down feathers and partly developed large feathers and can keep warm and get around without mum's help. "Previous studies searched for but failed to find any hints of feathers on the Los Hoyas hatchling. This meant that its original lifestyle was a mystery," says Dr Pittman.

Michael Pittman and Thomas Kaye brought new technology to the study of Los Hoyas fossils in the form of a high power laser. This made very small chemical differences in the fossils become visible by fluorescing them different colours, revealing previously unseen anatomical details. They recently had tremendous success with the first discovered fossil feather which they disassociated from the famous early bird Archaeopteryx by recovering the chemical signature of its fossil quill, a key part of the feather's identification that had been previously unverified for ~150 years. The new results on the hatchling bird finally answered the question about its lifestyle as it did indeed have feathers at birth and was thus precocial and out of the egg running. The feathers were made of carbon which has low fluorescence using Laser-Stimulated Fluorescence (LSF), but the background matrix did glow making the feathers stand out in dramatic dark silhouette. "Previous attempts using UV lights and synchrotron beams failed to detect the feathers, underscoring that the laser technology stands alone as a new tool in palaeontology" added Tom Kaye, the study's lead author.

This discovery via new technology demonstrates that some early birds adopted a precocial breeding strategy just like modern birds. Thus, in the time of the dinosaurs, some enantiornithine bird babies had the means to avoid the dangers of Mesozoic life perhaps by following their parents or moving around themselves. "One of the feathers discovered was of a substantial size and preserves features seen in other hatchlings. It indicates that our hatchling had reasonably well-developed flight feathers at the time of birth," says Jesús Marugán-Lobón, a co-author from the Universidad Autónoma of Madrid, Spain. This and other "illuminating" discoveries are adding to our knowledge of ancient life with details surviving in the fossil record that were never thought possible even a couple decades ago.

From Science Daily

Physicists reveal why matter dominates our universe

Why does matter dominate our universe?

Physicists in the College of Arts and Sciences at Syracuse University have confirmed that matter and antimatter decay differently for elementary particles containing charmed quarks.

Distinguished Professor Sheldon Stone says the findings are a first, although matter-antimatter asymmetry has been observed before in particles with strange quarks or beauty quarks.

He and members of the College's High-Energy Physics (HEP) research group have measured, for the first time and with 99.999-percent certainty, a difference in the way D0mesons and anti-D0 mesons transform into more stable byproducts.

Mesons are subatomic particles composed of one quark and one antiquark, bound together by strong interactions.

"There have been many attempts to measure matter-antimatter asymmetry, but, until now, no one has succeeded," says Stone, who collaborates on the Large Hadron Collider beauty (LHCb) experiment at the CERN laboratory in Geneva, Switzerland. "It's a milestone in antimatter research."

The findings may also indicate new physics beyond the Standard Model, which describes how fundamental particles interact with one another. "Till then, we need to await theoretical attempts to explain the observation in less esoteric means," he adds.

Every particle of matter has a corresponding antiparticle, identical in every way, but with an opposite charge. Precision studies of hydrogen and antihydrogen atoms, for example, reveal similarities to beyond the billionth decimal place.

When matter and antimatter particles come into contact, they annihilate each other in a burst of energy -- similar to what happened in the Big Bang, some 14 billion years ago.

"That's why there is so little naturally occurring antimatter in the Universe around us," says Stone, a Fellow of the American Physical Society, which has awarded him this year's W.K.H. Panofsky Prize in Experimental Particle Physics.

The question on Stone's mind involves the equal-but-opposite nature of matter and antimatter. "If the same amount of matter and antimatter exploded into existence at the birth of the Universe, there should have been nothing left behind but pure energy. Obviously, that didn't happen," he says in a whiff of understatement.

Thus, Stone and his LHCb colleagues have been searching for subtle differences in matter and antimatter to understand why matter is so prevalent.

The answer may lie at CERN, where scientists create antimatter by smashing protons together in the Large Hadron Collider (LHC), the world's biggest, most powerful particular accelerator. The more energy the LHC produces, the more massive are the particles -- and antiparticles -- formed during collision.

It is in the debris of these collisions that scientists such as Ivan Polyakov, a postdoc in Syracuse's HEP group, hunt for particle ingredients.

"We don't see antimatter in our world, so we have to artificially produce it," he says. "The data from these collisions enables us to map the decay and transformation of unstable particles into more stable byproducts."

HEP is renowned for its pioneering research into quarks -- elementary particles that are the building blocks of matter. There are six types, or flavors, of quarks, but scientists usually talk about them in pairs: up/down, charm/strange and top/bottom. Each pair has a corresponding mass and fractional electronic charge.

In addition to the beauty quark (the "b" in "LHCb"), HEP is interested in the charmed quark. Despite its relatively high mass, a charmed quark lives a fleeting existence before decaying into something more stable.

Recently, HEP studied two versions of the same particle. One version contained a charmed quark and an antimatter version of an up quark, called the anti-up quark. The other version had an anti-charm quark and an up quark.

Using LHC data, they identified both versions of the particle, well into the tens of millions, and counted the number of times each particle decayed into new byproducts.

"The ratio of the two possible outcomes should have been identical for both sets of particles, but we found that the ratios differed by about a tenth of a percent," Stone says. "This proves that charmed matter and antimatter particles are not totally interchangeable."

Adds Polyakov, "Particles might look the same on the outside, but they behave differently on the inside. That is the puzzle of antimatter."

The idea that matter and antimatter behaves differently is not new. Previous studies of particles with strange quarks and bottom quarks have confirmed as such.

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Evidence for a Human Geomagnetic Sense

Research shows the changes in alpha wave amplitude --- a measure of whether the brain is being engaged or is in a resting or "autopilot" mode --- following rotations of an Earth-strength magnetic field. On the left, counterclockwise rotations induce a widespread drop in alpha wave amplitude. No drop is observed after clockwise rotation or in the FIXED condition.

Scientists develop a robust experiment that shows human brain waves respond to changes in Earth-strength magnetic fields.

Many humans are able to unconsciously detect changes in Earth-strength magnetic fields, according to scientists at Caltech and the University of Tokyo.

The study, led by geoscientist Joseph Kirschvink (BS, MS '75) and neuroscientist Shin Shimojo at Caltech as well as neuroengineer Ayu Matani at the University of Tokyo, offers experimental evidence that human brain waves respond to controlled changes in Earth-strength magnetic fields. Kirschvink and Shimojo say this is the first concrete evidence of a new human sense: magnetoreception. Their findings were published by the journal eNeuro on March 18.

"Many animals have magnetoreception, so why not us?" asks Connie Wang, Caltech graduate student and lead author of the eNeuro study. For example, honeybees, salmon, turtles, birds, whales, and bats use the geomagnetic field to help them navigate, and dogs can be trained to locate buried magnets. It has long been theorized that humans may share a similar ability. However, despite a flurry of research attempting to test for it in the '80s, it has never been conclusively demonstrated.

"Aristotle described the five basic senses as including vision, hearing, taste, smell, and touch," says Kirschvink, co-corresponding author of the eNeuro study and Nico and Marilyn Van Wingen Professor of Geobiology. "However, he did not consider gravity, temperature, pain, balance, and several other internal stimuli that we now know are part of the human nervous system. Our animal ancestry argues that geomagnetic field sensors should also be there representing not the sixth sense but perhaps the 10th or 11th human sense to be discovered."

To try to determine whether humans do sense magnetic fields, Kirschvink and Shimojo built an isolated radiofrequency-shielded chamber and had participants sit in silence and utter darkness for an hour. During that time, they shifted the magnetic field silently around the chamber and measured participants' brain waves via electrodes positioned at 64 locations on their heads.

The test was performed with 34 human participants from a wide age range and a variety of ethnicities. During a given session, the participants consciously experienced nothing more interesting than sitting alone in the dark. However, among many participants, changes in their brain waves correlated with changes in the magnetic field around them. Specifically, the researchers tracked the alpha rhythm in the brain, which occurs at between 8 and 13 Hertz and is a measure of whether the brain is being engaged or is in a resting or "autopilot" mode. When a human brain is unengaged, the alpha power is high. When something catches its attention, consciously or unconsciously, its alpha power drops. Several other sensory stimuli like vision, hearing, and touch are known to cause abrupt drops in the amplitude of alpha waves in the first few seconds after the stimulus.

The experiments showed that, in some participants, alpha power began to drop from baseline levels immediately after magnetic stimulation, decreasing by as much as 60 percent over several hundred milliseconds, then recovering to baseline a few seconds after the stimulus. "This is a classic, well-studied brain wave response to a sensory input, termed event-related desynchronization, or alpha-ERD," says Shimojo, Gertrude Baltimore Professor of Experimental Psychology and affiliated faculty member of the Tianqiao and Chrissy Chen Institute for Neuroscience at Caltech.

The tests further revealed that the brain appears to be actively processing magnetic information and rejecting signals that are not "natural." For example, when the vertical component of the magnetic field pointed steadily upward during the experiments, there were no corresponding changes in brain waves. Because the magnetic field normally points down in the Northern Hemisphere, it seems that the brain is ignoring signals that are obviously "wrong." This component of the study could be verified by replicating the experiment in the Southern Hemisphere, Kirschvink suggests, where the opposite pattern should hold.

"Alpha-ERD is a strong neural signature of sensory detection and the resulting attention shift. The fact that we see it in response to simple magnetic rotations like we experience when turning or shaking our head is powerful evidence for human magnetoreception. The large individual differences we found are also intriguing with regard to human evolution and the influences of modern life," says Shimojo. "As for the next step, we ought to try bringing this into conscious awareness."

One of the challenges in early attempts to test human magnetoreception was the difficulty of making sure that those changes in brain waves were, indeed, correlated to the magnetic field and not to some other confounding effect. For example, if the coils generating the magnetic field around the chamber created an audible hum, that might be enough to trigger a change in alpha power in participants.

To address those issues, the chamber used in this study was not only pitch black and isolated, the copper wires for altering the magnetic field were wrapped and cemented in place in duplicate: each coil has a pair of wires rather than a single strand. When current is directed through these wire pairs in the same direction, the magnetic field in the chamber is altered. However, running the current in opposite directions through the wires in the pairs cancels their magnetic fields, while yielding the same electrical heating and mechanical artifacts. Computers completely controlled the experiments and recorded the data. Results were processed automatically with turn-key computer scripts and no subjective steps. In this fashion, the team was able to show that the human brains did, indeed, respond to the magnetic field as opposed to just the energizing of the coils themselves.

"Our results rule out electrical induction and the 'quantum compass' hypotheses for the magnetic sense," says Kirschvink, naming two possibilities that have been proposed for explaining the mechanism behind magnetoreception. Kirschvink suggests instead that the results implicate biological magnetite as the sensory agent for human magnetoreception. In 1962, Heinz A. Lowenstam, a Caltech professor from 1954 until his death in 1993, discovered that magnetite, a naturally magnetic mineral, occurs in mollusk teeth. Since then, biological magnetite has been found to exist in organisms from bacteria to humans and has been linked to the geomagnetic sense in many of them.

By developing and demonstrating a robust methodology for testing humans for magnetoreception, Kirschvink says he hopes this study can act as a roadmap for other researchers who are interested in attempting to replicate and extend this research. "Given the known presence of highly evolved geomagnetic navigation systems in species across the animal kingdom, it is perhaps not surprising that we might retain at least some functioning neural components, especially given the nomadic hunter-gatherer lifestyle of our not-too-distant ancestors. The full extent of this inheritance remains to be discovered," he says.

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Giant X-ray 'chimneys' are exhaust vents for vast energies produced at Milky Way's center

Galactic chimneys (yellow-orange areas) are centered on the supermassive black hole at the center of our galaxy. (This is a false-color image; white patches indicate spots where unrelated, bright X-ray sources have been removed from the image.)

The center of our galaxy is a frenzy of activity. A behemoth black hole -- 4 million times as massive as the sun -- blasts out energy as it chows down on interstellar detritus while neighboring stars burst to life and subsequently explode.

Now, an international team of astronomers has discovered two exhaust channels -- dubbed "galactic center chimneys" -- that appear to funnel matter and energy away from the cosmic fireworks in the Milky Way's center, about 28,000 light-years from Earth.

Mark Morris, a UCLA professor of astronomy and astrophysics, contributed to the research, which will be published March 21 in the journal Nature.

"We hypothesize that these chimneys are exhaust vents for all the energy released at the center of the galaxy," Morris said.

All galaxies are giant star-forming factories, but their productivity can vary widely -- from one galaxy to the next and even over the course of each galaxy's lifetime. One mechanism for throttling the rate of star production is the fountain of matter and energy whipped up by the heavyweight black hole that lurks at a galaxy's center.

"Star formation determines the character of a galaxy," Morris said. "And that's something we care about because stars produce the heavy elements out of which planets -- and life -- are made."

To better understand what becomes of that outflow of energy, Morris and his colleagues pointed the European Space Agency's XMM-Newton satellite, which detects cosmic X-rays, toward the center of the Milky Way. Because X-rays are emitted by extremely hot gas, they are especially useful for mapping energetic environments in space.

In images they collected from 2016 to 2018 and in 2012, the researchers found two plumes of X-rays -- the galactic center chimneys -- stretching in opposite directions from the central hub of the galaxy. Each plume originates within about 160 light-years of the supermassive black hole and spans over 500 light-years.

The chimneys hook up to two gargantuan structures known as the Fermi bubbles, cavities carved out of the gas that envelops the galaxy. The bubbles, which are filled with high-speed particles, straddle the center of the galaxy and stretch for 25,000 light-years in either direction. Some astronomers suspect that the Fermi bubbles are relics of massive eruptions from the supermassive black hole, while others think the bubbles are blown out by hordes of newly born stars. Either way, the chimneys could be the conduits through which high-speed particles get there.

Understanding how energy makes its way from a galaxy's center to its outer limits could provide insights into why some galaxies are bursting with star formation whereas others are dormant.

"In extreme cases, that fountain of energy can either trigger or shut off star formation in the galaxy," Morris said.

Our galaxy isn't quite that extreme -- other galaxies have fountains powered by central black holes weighing a thousand times more than ours -- but the Milky Way's center provides an up-close look at what might be happening in galaxies that are more energetic.

"We know that outflows and winds of material and energy emanating from a galaxy are crucial in sculpting and altering that galaxy's shape over time -- they're key players in how galaxies, and other structures, form and evolve throughout the cosmos," said lead author Gabriele Ponti of the Max Planck Institute for Extraterrestrial Physics in Garching, Germany. "Luckily, our galaxy gives us a nearby laboratory to explore this in detail, and probe how material flows out into the space around us."

Morris said the centers of the nearest galaxies are hundreds to thousands of times farther away than our own. "The amount of energy coming out of the center of our galaxy is limited, but it's a really good example of a galactic center that we can observe and try to understand," he said.

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Butterfly numbers down by two thirds

Hominy Blue (Polyommatus icarus).

Meadows adjacent to high-intensity agricultural areas are home to less than half the number of butterfly species than areas in nature preserves. The number of individuals is even down to one-third of that number. These are results of a research team led by Jan Christian Habel at the Technical University of Munich (TUM) and Thomas Schmitt at the Senckenberg Nature Research Society.

Germany is home to roughly 33,500 species of insects -- but their numbers are decreasing dramatically. Of the 189 species of butterflies currently known from Germany, 99 species are on the Red List, 5 have already become extinct, and 12 additional species are threatened with extinction.

Now a team led by Prof. Jan-Christian Habel of the Department of Terrestrial Ecology of the Technical University of Munich and Prof. Thomas Schmitt, Director of the Senckenberg German Entomological Institute in Muencheberg in Brandenburg, has examined the specific effects of the intensity of agricultural use on the butterfly fauna.

Reduced biodiversity also on areas around intensively cultivated fields

The research team recorded the occurrence of butterfly species in 21 meadow sites east of Munich. Of these study sites, 17 are surrounded by agriculturally used areas, and four are in nature preserves with near-natural cultivation.

They recorded a total of 24 butterfly species and 864 individuals in all study sites. Specialists among the butterflies were particularly dependent on near-natural habitats, while the more adaptable "generalists" were also found in other grassland sites.

"In the meadows that are surrounded by agriculturally used areas we encountered an average of 2.7 butterfly species per visit; in the four study sites within the protected areas 'Dietersheimer Brenne' and 'Garchinger Heide' near Munich we found an average of 6.6 species," adds Prof. Werner Ulrich of the Copernicus University in Thorn, Poland.

Negative impact of the industrialized agriculture demands rethinking

"Our results show an obvious trend: in the vicinity of intensively cultivated fields that are regularly sprayed with pesticides, the diversity and numbers of butterflies are significantly lower than in meadows near less used or unused areas," explains the study's lead author, Prof. Jan Christian Habel.

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Tiny song bird makes record migration

Blackpoll warbler wearing tiny 'backpack.'

It's an epic journey for a tiny bird.

For the first time, University of Guelph biologists have tracked an annual migration of up to 20,000 kilometres made by the 12-gram blackpoll warbler, one of the fastest declining songbirds in North America.

The bird's trek between its breeding grounds in the central and western boreal forest of North America and its winter home in the Amazon Basin -- one of the longest songbird migrations recorded -- is the topic of a new paper by a research team headed by U of G biologist Ryan Norris.

The paper was published today in the journal Ecology.

Describing a "great circle route" arcing across North America and including a transoceanic flight to South America, the study confirms an epic migration journey that scientists had long suspected but not yet proved.

In 2015, Norris and other biologists were the first to show that blackpolls breeding in the Maritimes and New England complete a non-stop transoceanic flight of up to three days and about 2,700 km along the eastern coast of the United States.

For this new study, they looked at the full migration of birds from central and western breeding populations.

"It's amazing," said Norris, who worked on the study with Hilary Cooke, associate conservation scientist with Wildlife Conservation Society Canada. "A bird weighing a couple of loonies travels from the western edge of North America all the way to the Amazon basin -- and, in between, traverses the Atlantic Ocean."

Other co-authors were integrative biology professor Amy Newman and U of G grad students Bradley Woodworth, Nikole Freeman and Alex Sutton, as well as researchers from other universities, conservation groups and national parks in Canada, the U.S. and Australia.

For the study, researchers tracked birds outfitted with tiny geolocators from four boreal forest sites across northern Canada and Alaska.

Total southward migration took about 60 days on average over distances ranging from 6,900 km for birds breeding in Churchill, Manitoba, to 10,700 km for populations on the western edge of the continent in Nome, Alaska.

Blackpolls from Nome took 18 days to fly across North America to the Atlantic coast of the Carolinas. There, the birds spent almost a month fattening up to double their body weight before a non-stop, 2 ½-day flight across open water to overwintering grounds in northern Colombia, Venezuela and Brazil.

They covered between 2,250 and 3,400 km for that transoceanic hop.

Norris said scientists had long believed that blackpolls followed the great circle route. Few of the birds have ever been found in the central or western States during fall migration.

He said population numbers have fallen in recent years, perhaps caused by habitat loss and declines in insect prey related to climate change.

"To understand what's causing the decline, we need to know their full annual cycle," he said.

In their paper, the researchers say climate change may make extreme coastal weather events more frequent and more extreme, with unknown impacts on long-distance migratory birds.

"As a conservation scientist, what strikes me most is that in a single year a blackpoll warbler has to navigate 20,000 kilometres across land and ocean, facing risks of cat predation, storms and collisions with buildings and vehicles, all while trying to find islands of habitat to rest and refuel in our human-dominated landscapes,"said Cooke. "In comparison, the boreal region of northern Canada provides safe and high-quality breeding habitat for this declining species. Protecting Canada's boreal forest is critical to saving this amazing songbird."

Read more at Science Daily

Water-bearing minerals on asteroid Bennu

This mosaic image of the asteroid Bennu is composed of 12 PolyCam images collected by the OSIRIS-REx spacecraft from 15 miles away. An SwRI-led team is looking at the spectral data from the surface to better understand the composition of the asteroid.

A Southwest Research Institute-led team discovered evidence of abundant water-bearing minerals on the surface of the near-Earth asteroid (101955) Bennu. Using early spectral data from NASA's OSIRIS-REx spacecraft orbiting the asteroid, the team identified infrared properties similar to those in a type of meteorite called carbonaceous chondrites.

"Scientists are interested in the composition of Bennu because similar objects may have seeded the Earth with water and organic materials," said SwRI's Dr. Victoria Hamilton, a mission co-investigator and lead author of a paper outlining the discovery published March 19 in Nature Astronomy. "OSIRIS-REx data confirm previous ground-based observations pointing to aqueously altered, hydrated minerals on the surface of the asteroid."

Typical planetary models show that around 4.6 billion years ago, the solar system formed from the gravitational collapse of a giant nebular cloud. The Sun, planets and other objects such as asteroids and comets formed as materials within the collapsing cloud clumped together in a process known as accretion. Carbonaceous chondrites, which come from asteroids, show evidence for post-accretion interactions with water and/or ice that led to chemical reactions that produce hydrated minerals. Because these meteorites and their parent bodies formed close to the beginning of the solar system, they may provide clues to the distribution, abundance and movements of water in the solar disk at these times.

"During planetary formation, scientists believe that water was one of many chemical components that accreted to form Earth; however, most scientists think additional water was delivered in part by comets and pieces of asteroids, including water-bearing carbonaceous meteorites," Hamilton said. "Many of these meteorites also contain prebiotic organic chemicals and amino acids, which are precursors to the origin of life. The details of water delivery to Earth as well as the larger issue of the different inventories of water ice in the early solar system affect how we view solar system formation."

Two types of carbonaceous chondrites called CI and CM chondrites contain several percent by weight of organic compounds and some also contain water in abundances of 10-15 percent and as much as 20 percent in rare cases. The presence of volatile organic chemicals and water indicates that they have not undergone substantial heating.

"Because asteroids with hydrated minerals are found throughout the main asteroid belt, significant ice must have been present in the disk during and shortly after the time of carbonaceous asteroid accretion," Hamilton said.

In summer of 2020, OSIRIS-REx will touch Bennu's surface to collect a sample the surface regolith for return to Earth. The spectral measurements used in this study will be confirmed by lab experiments when a sample of Bennu's surface materials arrives back at Earth in 2023.

The geological characteristics of Bennu's surface indicate that it is an old rubble pile of gravitationally bound, unconsolidated fragments, left over from an ancient collision in the asteroid belt. These and future, higher-resolution spectral observations from OSIRIS-REx will provide vital context for analyzing the returned sample to evaluate the aqueous alteration experienced by Bennu's parent body based on details of mineral distribution, abundance and composition.

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The rise and fall of Ziggy star formation and the rich dust from ancient stars

Based on the observations with ALMA and HST, researchers assume that this galaxy contains stellar clusters with a mix of old and young stars. The clouds of gas and dust are illuminated by stellar light.

Researchers have detected a radio signal from abundant interstellar dust in MACS0416_Y1, a galaxy 13.2 billion light-years away in the constellation Eridanus. Standard models can't explain this much dust in a galaxy this young, forcing us to rethink the history of star formation. Researchers now think MACS0416_Y1 experienced staggered star formation with two intense starburst periods 300 million and 600 million years after the Big Bang with a quiet phase in between.

Stars are the main players in the Universe, but they are supported by the unseen backstage stagehands: star dust and gas. Cosmic clouds of dust and gas are the sites of star formation and masterful storytellers of the cosmic history.

"Dust and relatively heavy elements such as oxygen are disseminated by the deaths of stars," said Yoichi Tamura, an associate professor at Nagoya University and the lead author of the research paper, "Therefore, a detection of dust at some point in time indicates that a number of stars have already formed and died well before that point."

Using ALMA (Atacama Large Millimeter/submillimeter Array), Tamura and his team observed the distant galaxy MACS0416_Y1. Because of the finite speed of light, the radio waves we observe from this galaxy today had to travel for 13.2 billion years to reach us. In other words they provide an image of what the galaxy looked like 13.2 billion years ago, which is only 600 million years after the Big Bang.

The astronomers detected a weak but telltale signal of radio emissions from dust particles in MACS0416_Y1 (Note 1). The Hubble Space Telescope, the Spitzer Space Telescope, and the European Southern Observatory's Very Large Telescope have observed the light from stars in the galaxy; and from its color they estimate the stellar age to be 4 million years.

"It ain't easy," said Tamura half-lost in a moonage daydream. "The dust is too abundant to have been formed in 4 million years. It is surprising, but we need to hang onto ourselves. Older stars might be hiding in the galaxy, or they may have died out and disappeared already."

"There have been several ideas proposed to overcome this 'dust budget crisis'," said Ken Mawatari, a researcher at the University of Tokyo. "However, no one is conclusive. We made a new model which doesn't need any extreme assumptions diverging far from our knowledge of the life of stars in today's Universe. The model well explains both the color of the galaxy and the amount of dust." In this model, the first burst of star formation started at 300 million years and lasted 100 million years. After that, the star formation activity went quiet for a time, and then restarted at 600 million years. The researchers think ALMA observed this galaxy at the beginning of its second generation of star formation.

Read more at Science Daily

It's spring already? Physics explains why time flies as we age

The 'endless days' of childhood.

A Duke University researcher has a new explanation for why those endless days of childhood seemed to last so much longer than they do now -- physics.

According to Adrian Bejan, the J.A. Jones Professor of Mechanical Engineering at Duke, this apparent temporal discrepancy can be blamed on the ever-slowing speed at which images are obtained and processed by the human brain as the body ages.

The theory was published online on March 18 in the journal European Review.

"People are often amazed at how much they remember from days that seemed to last forever in their youth," said Bejan. "It's not that their experiences were much deeper or more meaningful, it's just that they were being processed in rapid fire."

Bejan attributes this phenomenon to physical changes in the aging human body. As tangled webs of nerves and neurons mature, they grow in size and complexity, leading to longer paths for signals to traverse. As those paths then begin to age, they also degrade, giving more resistance to the flow of electrical signals.

These phenomena cause the rate at which new mental images are acquired and processed to decrease with age. This is evidenced by how often the eyes of infants move compared to adults, noted Bejan -- because infants process images faster than adults, their eyes move more often, acquiring and integrating more information.

The end result is that, because older people are viewing fewer new images in the same amount of actual time, it seems to them as though time is passing more quickly.

"The human mind senses time changing when the perceived images change," said Bejan. "The present is different from the past because the mental viewing has changed, not because somebody's clock rings. Days seemed to last longer in your youth because the young mind receives more images during one day than the same mind in old age."

From Science Daily

Mammals' unique arms started evolving before the dinosaurs existed

Photographs of the upper arm bones from seven kinds of early mammal relatives. The three bones on the left are from an early group called pelycosaurs, and the bones are all roughly the same shape. The four bones on the right are from therapsids, the group that includes today's mammals, and they show the greater variety of shapes and sizes that characterize therapsid limbs. The black scale bars represent 2cm.

Bats fly, whales swim, gibbons swing from tree to tree, horses gallop, and humans swipe on their phones -- the different habitats and lifestyles of mammals rely on our unique forelimbs. No other group of vertebrate animals has evolved so many different kinds of arms: in contrast, all birds have wings, and pretty much all lizards walk on all fours. Our forelimbs are a big part of what makes mammals special, and in a new study in the Proceedings of the National Academy of Sciences, scientists have discovered that our early relatives started evolving diverse forelimbs 270 million years ago -- a good 30 million years before the earliest dinosaurs existed.

"Aside from fur, diverse forelimb shape is one of the most iconic characteristics of mammals," says the paper's lead author Jacqueline Lungmus, a research assistant at Chicago's Field Museum and a doctoral candidate at the University of Chicago. "We were trying to understand where that comes from, if it's a recent trait or if this has been something special about the group of animals that we belong to from the beginning."

To determine the origins of mammals' arms today, Lungmus and her co-author, Field Museum curator Ken Angielczyk, examined the fossils of mammals' ancient relatives. About 312 million years ago, land-dwelling vertebrates split into two groups -- the sauropsids, which went on to include dinosaurs, birds, crocodiles, and lizards, and the synapsids, the group that mammals are part of. A key difference between sauropsids and synapsids is the pattern of openings in the skull where jaw muscles attach. While the earliest synapsids, called pelycosaurs, were more closely related to humans than to dinosaurs, they looked like hulking reptiles. Angielczyk notes, "If you saw a pelycosaur walking down the street, you wouldn't think it looked like a mammal -- you'd say, 'That's a weird-looking crocodile.'"

About 270 million years ago, though, a more diverse (and sometimes furry) line of our family tree emerged: the therapsids. "Modern mammals are the only surviving therapsids -- this is the group that we're part of today," explains Lungmus. Therapsids were the first members of our family to really branch out -- instead of just croc-like pelycosaurs, the therapsids included lithe carnivores, burly-armed burrowers, and tree-dwelling plant-eaters.

Lungmus and Angielczyk set out to see if this explosion of diversity came with a corresponding explosion in different forelimb shapes. "This is the first study to quantify forelimb shape across a big sample of these animals," says Lungmus. The team examined the upper arm bones of hundreds of fossil specimens representing 73 kinds of pelycosaurs and therapsids, taking measurements near where the bones joined the shoulder and the elbow. They then analyzed the shapes of the bones using a technique called geometric morphometrics.

When they compared the shapes of arm bones, the researchers found a lot more variation in the bones of the therapsids than the pelycosaurs. They also noted that the upper part of the arm, near the shoulder, was especially varied in therapsids -- a feature that might have let them move more freely than the pelycosaurs, whose bulky and tightly-fitting shoulder bones likely gave them a more limited range of motion.

Lungmus and Angielczyk found that a wide variety of different forelimb shapes evolved within the therapsids 270 million years ago. "The therapsids are the first synapsids to increase the variability of their forelimbs -- this study dramatically pushes that trait back in time," says Lungmus. Prior to this study, the earliest that paleontologists had been able to definitively trace back mammals' diverse forelimbs was 160 million years ago. With Lungmus and Angielczyk's work, that's been pushed back by more than a hundred million years.

The researchers note that the study helps explain how mammals evolved traits that have made us what we are today. "So much of what we do every day is related to the way our forelimbs evolved -- even simple things like holding a phone," says Angielczyk.

Read more at Science Daily

Natural selection favors cheaters

Acmispon strigosus is an annual herb that is native to California.

Mutualisms, which are interactions between members of different species that benefit both parties, are found everywhere -- from exchanges between pollinators and the plants they pollinate, to symbiotic interactions between us and our beneficial microbes.

Natural selection -- the process whereby organisms better adapted to their environment tend to survive and produce more offspring -- predicts, however, that mutualisms should fall apart. Individuals that gain from the cooperation of others but do not reciprocate (so-called cheaters) should arise and destabilize mutualisms. Yet to date, surprisingly little evidence of such cheating or destabilization exists.

A team of biologists at the University of California, Riverside, has now found strong evidence of this cheating. Focusing on the interaction between nitrogen-fixing bacteria, or rhizobia, and their legume hosts spanning about 530 miles of California habitat, the researchers found that natural selection in their study populations favors cheating rhizobia.

The study, appearing in Ecology Letters, is the first to uncover cheater strains in natural populations and show how natural selection favors them.

The researchers used a previously published database to quantify the landscape abundance of different rhizobial strains. They focused on naturally occurring populations of rhizobia in the genus Bradyrhizobium and the native annual plants, Acmispon strigosus, that these bacteria inhabit. Within these datasets they found that the fewer benefits the rhizobia provide to their host plants, the more common the rhizobia are.

"Our data show that natural selection favors cheating rhizobia, and support predictions that rhizobia can often subvert plant defenses and evolve to exploit hosts," said Joel Sachs, a professor of biology in the Department of Evolution, Ecology & Organismal Biology, who led the research team.

Sachs explained that beneficial bacteria are increasingly appreciated to be key for human health as well as the productivity of crops and livestock. Little is understood, however, about how much these bacterial services vary in natural systems and the forces that modulate them.

"In crop plants, in particular, agronomists have attempted -- and failed -- for several decades to design crop biofertilizers based on beneficial bacteria," he said. "Similar challenges have been faced in applying bacteria in other host systems -- probiotics, for example, which rarely affect host microbes. Our dataset suggests a potential flaw in these approaches; the bacteria, with their own evolutionary interests, can destabilize these interactions."

In their paper, the researchers show how benefits of bacterial symbionts vary over space and time, and how rapidly these systems can evolve.

"We often view the services of bacteria as fixed, but this is not at all true," Sachs said. "Just as each human varies a great deal in almost any trait we can measure, bacterial populations are even more highly variable. Understanding this variation and its drivers will be key to usefully harnessing these bacteria for our own purposes."

Already, his team is actively working to better understand how beneficial bacteria can be applied to improve plant growth. Preliminary data show that it is crucial to carefully select among bacterial variants to avoid using harmful strains.

"Simply applying beneficial bacteria to a crop is often not going to be sufficient since exploitative strains are expected to be lurking within these populations," Sachs said.

Read more at Science Daily

Weird, wild gravity of asteroid Bennu

The asteroid Bennu as seen by the OSIRIS-REx spacecraft. The flying saucer-like shape of Bennu is generated, in part, by its spin.

Research led by the University of Colorado Boulder is revealing the Alice in Wonderland-like physics that govern gravity near the surface of the asteroid Bennu.

The new findings are part of a suite of papers published today by the team behind NASA's Origins, Spectral Interpretation, Resource Identification, Security-Regolith Explorer (OSIRIS-REx) mission. And they come just three months after OSIRIS-REx first encountered Bennu on Dec. 3, 2018.

Since then, the spacecraft has completed a few dozen laps around the asteroid, which is about as tall as the Empire State Building, circling Bennu from a distance of about a mile. And those early circuits are giving scientists a whole new look at this mysterious rock, said CU Boulder's Daniel Scheeres, who leads the mission's radio science team.

In research appearing in Nature Astronomy, for example, his team reports the mass of that asteroid: a respectable 73 billion kilograms.

But Scheeres and his colleagues are also working to develop a map of the asteroid's gravitational pull. Their findings suggest that Bennu exists in a delicate balance between two competing forces, the result of the asteroid's wild spin. Bennu completes a full revolution about once every four hours.

And, Scheeres said, those forces could play an important role in the asteroid's long-term evolution -- and potential demise.

"When you spin this guy up, you create a competition between the gravity that's holding you down and the centrifugal acceleration, which is trying to throw you off," said Scheeres, distinguished professor in the Ann and H.J. Smead Department of Aerospace Engineering Sciences who leads the mission's radio science team.

To study those forces, Scheeres and his colleagues use OSIRIS-REx's navigational instruments to measure the minute tug that the asteroid exerts on the spacecraft.

And they dug up more than they expected. Based on the group's calculations, the region around Bennu's equator is trapped within a gravitational feature called a rotational Roche lobe -- something that scientists had not yet clearly observed on an asteroid.

In practice, that feature gets weird. If you were standing inside the boundaries of Bennu's Roche lobe and slipped on a banana peel, for example, not much would happen -- you'd be captured by the lobe and fall back to the surface.

"But if you were outside of the Roche lobe and slipped on a banana peel, you would roll toward the equator," Scheeres said. "And you could gain enough energy so that you'd roll off the equator and maybe up into orbit and then out into space."

It sounds like the sort of environment that Lewis Carroll could appreciate. But it also matters for the lifespan of Bennu, he added.

That's because radiation from the sun is causing Bennu to spin faster and faster over time. And as the asteroid's whirling builds up speed, its Roche lobe might also be shrinking, along with the forces that are holding Bennu together.

"As that Roche lobe narrows further and further around the equator, it becomes easier and easier for this asteroid to lose material," Scheeres said. "So far, that material has been trapped by gravity, but at some point, if the asteroid keeps spinning faster, then you fall off the cliff."

In other words, Bennu could be in the process of spinning itself into oblivion.

Understanding those physics matters for advance OSIRIS-REx's scientific mission, too, said Jay McMahon, an assistant professor in aerospace engineering and a co-author of the new study.

He explained that in 2020, mission scientists will nudge OSIRIS-REx to within a few feet of Bennu, using the spacecraft's retractable arm to collect a sample of material from the surface. And to do that safely, they will need to know the rock's physics inside and out.

"You need to know the gravitational field for spacecraft operations, really to enable all the other science," McMahon said.

"When you're going to a new world, you have some idea of what it might look like," Scheeres said. "Then you actually go there, and you can start comparing what you thought it might look like versus reality."

The University of Arizona leads science operations for OSIRIS-REx, which was built by the Colorado-based Lockheed Martin Space. NASA's Goddard Space Flight Center in Maryland manages the overall mission.

Read more at Science Daily

Researchers create hydrogen fuel from seawater

A prototype device used solar energy to create hydrogen fuel from seawater.

Stanford researchers have devised a way to generate hydrogen fuel using solar power, electrodes and saltwater from San Francisco Bay.

The findings, published March 18 in Proceedings of the National Academy of Sciences, demonstrate a new way of separating hydrogen and oxygen gas from seawater via electricity. Existing water-splitting methods rely on highly purified water, which is a precious resource and costly to produce.

Theoretically, to power cities and cars, "you need so much hydrogen it is not conceivable to use purified water," said Hongjie Dai, J.G. Jackson and C.J. Wood professor in chemistry at Stanford and co-senior author on the paper. "We barely have enough water for our current needs in California."

Hydrogen is an appealing option for fuel because it doesn't emit carbon dioxide, Dai said. Burning hydrogen produces only water and should ease worsening climate change problems.

Dai said his lab showed proof-of-concept with a demo, but the researchers will leave it up to manufacturers to scale and mass produce the design.

Tackling corrosion

As a concept, splitting water into hydrogen and oxygen with electricity -- called electrolysis -- is a simple and old idea: a power source connects to two electrodes placed in water. When power turns on, hydrogen gas bubbles out of the negative end -- called the cathode -- and breathable oxygen emerges at the positive end -- the anode.

But negatively charged chloride in seawater salt can corrode the positive end, limiting the system's lifespan. Dai and his team wanted to find a way to stop those seawater components from breaking down the submerged anodes.

The researchers discovered that if they coated the anode with layers that were rich in negative charges, the layers repelled chloride and slowed down the decay of the underlying metal.

They layered nickel-iron hydroxide on top of nickel sulfide, which covers a nickel foam core. The nickel foam acts as a conductor -- transporting electricity from the power source -- and the nickel-iron hydroxide sparks the electrolysis, separating water into oxygen and hydrogen. During electrolysis, the nickel sulfide evolves into a negatively charged layer that protects the anode. Just as the negative ends of two magnets push against one another, the negatively charged layer repels chloride and prevents it from reaching the core metal.

Without the negatively charged coating, the anode only works for around 12 hours in seawater, according to Michael Kenney, a graduate student in the Dai lab and co-lead author on the paper. "The whole electrode falls apart into a crumble," Kenney said. "But with this layer, it is able to go more than a thousand hours."

Previous studies attempting to split seawater for hydrogen fuel had run low amounts of electric current, because corrosion occurs at higher currents. But Dai, Kenney and their colleagues were able to conduct up to 10 times more electricity through their multi-layer device, which helps it generate hydrogen from seawater at a faster rate.

"I think we set a record on the current to split seawater," Dai said.

The team members conducted most of their tests in controlled laboratory conditions, where they could regulate the amount of electricity entering the system. But they also designed a solar-powered demonstration machine that produced hydrogen and oxygen gas from seawater collected from San Francisco Bay.

And without the risk of corrosion from salts, the device matched current technologies that use purified water. "The impressive thing about this study was that we were able to operate at electrical currents that are the same as what is used in industry today," Kenney said.

Surprisingly simple

Looking back, Dai and Kenney can see the simplicity of their design. "If we had a crystal ball three years ago, it would have been done in a month," Dai said. But now that the basic recipe is figured out for electrolysis with seawater, the new method will open doors for increasing the availability of hydrogen fuel powered by solar or wind energy.

In the future, the technology could be used for purposes beyond generating energy. Since the process also produces breathable oxygen, divers or submarines could bring devices into the ocean and generate oxygen down below without having to surface for air.

Read more at Science Daily

Scientists hunt down the brain circuit responsible for alcohol cravings

Confocal analysis at 63x magnification, followed by the three-dimensional reconstruction of neuronal cell bodies and branches. The image shows an example of eYFP and CRF in the same neuron. This rendered isosurface analysis demonstrated the colocalization of CRF immunoreactivity within CeA neurons that also expressed Cre-dependent eYFP and validates the crh-Cre rat as a tool to gain more direct access to CRF neurons to study their functional neuroanatomy.

Scientists at Scripps Research have found that they can reverse the desire to drink in alcohol-dependent rats -- with the flip of a switch. The researchers were able to use lasers to temporarily inactivate a specific neuronal population, reversing alcohol-seeking behavior and even reducing the physical symptoms of withdrawal.

"This discovery is exciting -- it means we have another piece of the puzzle to explain the neural mechanism driving alcohol consumption," says Olivier George, PhD, an associate professor at Scripps Research and senior author of the new study, published March 18, 2019 in the journal Nature Communications.

Although the laser treatment is far from ready for human use, George believes identifying these neurons opens the door to developing drug therapies or even gene therapies for alcohol addiction.

"We need compounds that are specific to this neuronal circuitry," George says.

According to the National Institute on Alcohol Abuse and Alcoholism, more than 15.1 million adults in the United States suffer from alcohol use disorder. Previous work at Scripps Research has shown that transitioning from casual drinking to dependent drinking occurs alongside fundamental changes in how the brain sends signals. These signals drive the intense cravings that make it so difficult for many people to scale back their alcohol consumption.

George and his colleagues have been hunting for the brain cells that driving drinking in an alcohol-addicted rat model. In 2016, they reported that they had found a possible source: a neuronal "ensemble," or group of connected cells in a brain region called the central nucleus of the amygdala (CeA). This finding marked major progress in mapping the brain, but the researchers needed to characterize the identity of the neurons in this ensemble.

For the new study, they tested the role of a subset of neurons in the ensemble, called corticotropin-releasing factor (CRF) neurons. The George laboratory had found that these CRF neurons make up 80 percent of the ensemble. Were these neurons the masterminds driving alcohol cravings?

The researchers studied these neurons using optogenetics, a technique that involves the use of light to control cells in living tissue. Rats used in this study were surgically implanted with optic fibers aimed to shine light on the CRF neurons -- to inactivate them at the flip of a switch.

First, the scientists established a baseline for how much the rats would drink before they got addicted to alcohol. The rats drank little this point -- the equivalent of a glass of wine or one beer for a human. The scientists then spent several months increasing consumption in these rats to establish alcohol dependence.

The researchers then withdrew the alcohol, prompting withdrawal symptoms in the rats. When they offered alcohol again, the rats drank more than ever. The CeA neuronal ensemble was active, telling the rats to drink more.

Then the scientists flipped on the lasers to inactivate the CRF neurons -- and the results were dramatic. The rats immediately returned to their pre-dependent drinking levels. The intense motivation to drink had gone away. Inactivating these neurons also reduced the physical symptoms of withdrawal, such as abnormal gait and shaking.

"In this multidisciplinary study, we were able to characterize, target and manipulate a critical subset of neurons responsible for excessive drinking." says Giordano de Guglielmo, PhD, first author of the study and staff scientist at Scripps Research. "This was a team effort, and while we used challenging techniques, working with experts in the field and with the right tools, made everything easier and enjoyable."

The effect was even reversible. Turn off the lasers, and the rats returned to their dependent behavior.

From a basic science standpoint, this breakthrough is huge: It reveals wiring in the brain that drives a specific, destructive behavior. George says the next step in translating this work to humans is to find a way to selectively inhibit only these specific CRF neurons, perhaps using a novel or repurposed compound identified using high-throughput screening of large libraries of compounds.

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Trembling aspen leaves could save future Mars rovers

The traditional harvester on the left, and the new harvester on the right.

Researchers at the University of Warwick have been inspired by the unique movement of trembling aspen leaves, to devise an energy harvesting mechanism that could power weather sensors in hostile environments and could even be a back-up energy supply that could save and extend the life of future Mars rovers.

University of Warwick third year engineering undergraduates have in recent years been set the task of the examining the puzzle of why Aspen leaves quiver in the presence of a slightest breeze. University of Warwick Engineering researchers Sam Tucker Harvey, Dr Igor A. Khovanov, and Dr Petr Denissenko were inspired to look more closely at this task they were annually setting for their students and to take the phenomenon one step further.

They decided to investigate whether the underlying mechanisms that produce the low wind speed quiver in Aspen leaves could efficiently and effectively generate electrical power, simply by exploiting the wind generated mechanical movement of a device modelled on the leaf. They have today 18th March 2019 published the answer to that question as a paper entitled "A Galloping Energy Harvester with Flow Attachment" in Applied Physics Letters and the answer is a resounding yes.

University of Warwick PhD engineering researcher Sam Tucker Harvey, the lead author on the paper, said:

"What's most appealing about this mechanism is that it provides a mechanical means of generating power without the use of bearings, which can cease to work in environments with extreme cold, heat, dust or sand. While the amount of potential power that could be generated is small, it would be more than enough to power autonomous electrical devices, such as those in wireless sensor networks. These networks could be utilised for applications such as providing automated weather sensing in remote and extreme environments."

Dr Petr Denissenko further noted that one future application could be as a backup power supply for future Mars landers and rovers.

"The performance of the Mars rover Opportunity far exceeded its designers' wildest dreams but even its hard working solar panels were probably eventually overcome by a planetary-scale dust storm. If we could equip future rovers with a backup mechanical energy harvester based on this technology, it may further the lives of the next generation of Mars rovers and landers."

The key to Aspen leaves' low wind but large amplitude quiver isn't just the shape the leaf but more importantly relates to the effectively flat shape of the stem.

The University of Warwick researchers used mathematical modelling to come up with a mechanical equivalent of the leaf. They then used a low speed wind tunnel to test a device with a cantilever beam like the flat stem of the Aspen leaf, and a curved blade tip with a circular arc cross section acting like the main leaf.

The blade was then oriented perpendicular to the flow direction, which allows the harvester to produce self-sustained oscillations at uncharacteristically low wind speeds like the aspen leaf. The tests showed that the air flow becomes attached to the rear face of the blade when the blade's velocity becomes high enough, hence acting more similarly to an aerofoil rather than to the bluff bodies which have typically been studied in the context of wind energy harvesting.

In nature, the propensity of a leaf to quiver is also enhanced by the thin stem's tendency to twist in the wind in two different directions. However, the researchers modelling and testing found that they did not need to replicate the additional complexity of a further degree of movement in their mechanical model. Simply replicating the basic properties of the flat stem in as a cantilever beam and curved blade tip with a circular arc cross section acting like the main leaf was enough to create sufficient mechanical movement to harvest power.

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Alligator study reveals insight into dinosaur hearing

American Alligators make neural maps of sound the same way birds do.

To determine where a sound is coming from, animal brains analyze the minute difference in time it takes a sound to reach each ear -- a cue known as interaural time difference. What happens to the cue once the signals get to the brain depends on what kind of animal is doing the hearing.

Scientists have known that birds are exceptionally good at creating neural maps to chart the location of sounds, and that the strategy differs in mammals. Little was known, however, about how alligators process interaural time difference.

A new study of American alligators found that the reptiles form neural maps of sound in the same way birds do. The research by Catherine Carr, a Distinguished University Professor of Biology at the University of Maryland, and her colleague Lutz Kettler from the Technische Universität München, was published in the Journal of Neuroscience on March 18, 2019.

Most research into how animals analyze interaural time difference has focused on physical features such as skull size and shape, but Carr and Kettler believed it was important to look at evolutionary relationships.

Birds have very small head sizes compared with alligators, but the two groups share a common ancestor -- the archosaur -- which predates dinosaurs. Archosaurs began to emerge around 246 million years ago and split into two lineages; one that led to alligators and one that led to dinosaurs. Although most dinosaurs died out during the mass extinction event 66 million years ago, some survived to evolve into modern birds.

Carr and Kettler's findings indicate that the hearing strategy birds and alligators share may have less to do with head size and more to do with common ancestry.

"Our research strongly suggests that this particular hearing strategy first evolved in their common ancestor," Carr said. "The other option, that they independently evolved the same complex strategy, seems very unlikely."

To study how alligators identify where sound comes from, the researchers anesthetized 40 American Alligators and fitted them with earphones. They played tones for the sleepy reptiles and measured the response of a structure in their brain stems called the nucleus laminaris. This structure is the seat of auditory signal processing. Their results showed that alligators create neural maps very similar to those previously measured in barn owls and chickens. The same maps have not been recorded in the equivalent structure in mammal brains.

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