Shuttling Electrons

first_img“We are trying to understand quantum nano-electro-mechanical systems,” Jason Twamley explains to PhysOrg.com. “These systems display richer dynamics and interactions than one can obtain with quantum optical systems, because it’s very hard to get photons to interact with each other.” Phonon-mediated quantum state transfer and remote qubit entanglement Citation: Shuttling Electrons (2006, June 5) retrieved 18 August 2019 from https://phys.org/news/2006-06-shuttling-electrons.html With the situation of the shuttle, the team discovered that it is possible to detect the spin. The spin on the shuttle causes the shuttle to move a tiny distance; this causes the current through the device to change. The change can be detected, measured, and interpreted, making it useful in a quantum computer or for spin-based classical computing, such as in the field of spintronics. One possibility for the shuttle is a molecule known as a “doped Buckyball.” These molecules, only recently discovered, are composed of 60 carbon atoms surrounding either phosphorous or nitrogen. The trapped atom, either nitrogen or phosphorous, sits at the center of the carbon cage and the charge neutral molecule has an overall spin of 3/2. Putting a Buckyball between two contacts and introducing a nanomagnet results in the ability to move the molecule to the left or to the right, depending on the molecule’s spin, shifting the current and providing a change to measure.Twamley readily admits that there are problems with the theory, the first being that the proposed device is a theory, and hasn’t been put into practice. “But,” he adds, “a lot of people are looking at these systems because such nano-electro-mechanical systems may yield ultra-precise measurements of the masses of biomolecules, and thus allow you to do bio-analysis on minute amounts of material.” On top of that, creating a quantum computer adds other challenges, due to the somewhat-mysterious nature of quantum mechanics. “It’s pretty wide open at the moment. What you have to be careful about is encoding qubits in degrees of freedom that are long-lived. If noise couples with them, the qubits die quickly, and can’t be used.” The trick to overcoming this, Twamley says, is experimentation. “With condensed matter systems, once you do the experiment, and probe how healthy the qubits really are in that physical system, you will know how much noise you have, and what could be done with the qubits before they die.”However, a mechanical device like that suggested by Twamley and his colleagues does have a clear advantage over optical quantum devices. “It’s hard to predict which technology will be used for quantum computing,” he explains. “But the nice thing about these nano-mechanical systems is that they interact with each other quite strongly as compared to optical systems.”By Miranda Marquit, Copyright 2006 PhysOrg.com. All rights reserved. This material may not be published, broadcast, rewritten or redistributed. Explore furthercenter_img This document is subject to copyright. Apart from any fair dealing for the purpose of private study or research, no part may be reproduced without the written permission. The content is provided for information purposes only. Artists impression of the spin-detection single molecule shuttle. The Buckyball containing the Nitrogen (or Phosphorous), is held between two gold electrodes by linking flexing molecules (shown schematically as springs). The shuttle picks up an electron (shown as glowing ball), from one electrode and then moves to the other electrode to dump the electron. The average current depends sensitively on the equilibrium position of the shuttle and via the interaction of the shuttle´s spin and nearby (unshown), nanomagnet. Credit: Jason Twamley Twamley, a professor of quantum information science at Macquarie University in Sydney, Australia, worked with various colleagues, including theorists from the University of Queensland in St. Lucia, Australia and National Taiwan University in Taipei to develop a quantum nano-mechanical system that could measure the spin of a single molecule and perhaps be part of solid-state quantum computer. Their paper on the subject, “Spin-detection in a quantum electromechanical shuttle system,” appears in the May issue of the New Journal of Physics. “Part of doing quantum computing,” Twamley explains, “is being able to input and output quantum bits (or qubits). If you are using a charge-based computer, you need to be able to read the charges. With spin-based, you need to read out spins.” Any quantum computer requires encoding quantum bits (qubits) into something. Twamley and his peers propose a readout device that would be able to detect changes in spin state of a single molecule, paving the way for spin-based input/output quantum computers in which qubits are inputted into the electron’s spin, and then decoded in the read-out to provide the asked-for information.Twamley and his colleagues propose a mechanical system, simple and based on a mobile quantum dot, often referred to as a single electron shuttle, to provide the means for measuring differences in spin. “We’re combining the charge features of the quantum dot with the dot’s motion, a combination which most nanoelectronics don’t even contemplate doing.” And while nanoelectronic systems are quite new, Twamley points out that they are already pushing beyond that: “We’ve add a ‘q’ to the front of it: quantum nano-electro-mechanical systems. We’re now working in the quantum regime and the experiments are very close to the quantum regime now.”The device comprises two electrodes, placed apart, and a quantum dot that acts as a shuttle, ferrying electrons from one to the other. Here’s how it works:“The shuttle moves toward the source electrode. There is a bit of a gap between the two, called a tunnel gap. The shuttle doesn’t touch the electrode. Classically, the tunnel gap is not something that the electron could go through. On the quantum level, though, there is a chance. The electron jumps through the tunnel, and its charge forces the shuttle to the other electrode, called the drain electrode. The electron then jumps through another tunnel to the drain electrode and the whole process repeats.”last_img read more

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Scientists study why the blind salamander lives so long

first_img © 2010 PhysOrg.com This document is subject to copyright. Apart from any fair dealing for the purpose of private study or research, no part may be reproduced without the written permission. The content is provided for information purposes only. Scientists develop resource to study animal aging More information: Extreme lifespan of the human fish (Proteus anguinus): a challenge for ageing mechanisms, Biology Letters, Published online before print July 21, 2010, doi:10.1098/rsbl.2010.0539 The blind salamander (Proteus anguinus), also known as the olm, has the longest lifespan of any amphibian, often living to over 70 in zoos, and with a predicted maximum age of over 100. It reaches sexual maturity during its fifteenth year and lays about 35 eggs every 12.5 years.The amphibian spends its entire life in water in the dark limestone caves in southern Europe. Its eyes are atrophied and it has almost no skin pigments. The skin looks pink because the blood shows through, leading to the olm sometimes being called the “human fish”.The olm is a snake-like creature 25-30 cm long and weighing only up to 20 grams. Most tiny creatures have short lifespans, which is thought to be due to having higher metabolisms that in essence burn the creatures out more quickly, but the olm has a similar metabolic rate to its closest relatives, which have much shorter lifespans. There is also no unusual antioxidant activity in the olm that might explain its longevity.Scientists at a cave station set up at Moulis, Saint-Girons in France have been studying the olm, an endangered species, since 1952. The cave is a faithful reproduction of the olm’s natural habitat and has over 400 salamanders in residence. It is the only successful breeding program of the amphibian, and the project is operated by the National Center for Scientific Research in France. Data on deaths and breeding activity have been recorded at the cave station since 1958.Ecophysiologist Yann Voituron and colleagues, from the Université Claude Bernard Lyon, have been studying the salamanders to try to understand why they live so long in comparison to their relatives. Voituron said they would like to look at the “usual genes associated with increases in lifespan, and maybe hope to detect something new.” They would also like to analyze the creatures on a cellular level and examine their mitochondria, for example, but this would necessitate killing the animals, and they do not want to do this because they have so few to work with.The scientists estimated the maximum age from the knowledge the oldest inhabitants of the cave are now at least 48 and probably in their mid or late fifties, and in related species the average lifespan is between 10 and 67 percent of the longest lifespan known for the species. This gives a conservative estimate of a maximum lifespan of 102 years for the olm, or almost double the maximum lifespan of other long-lived amphibians such as the Japanese giant salamander, with a maximum of 55 years.Voituron said the studies have shown the olm is extremely inactive and rarely moves except to feed and to reproduce (which only happens every 12.5 years). There are no predators in the caves, so they live a stress-free life. The researchers think the salamander’s limited activity and an adjusted physiology may be a way to reduce production of reactive oxygen species (that damage cells as they age) without increased antioxidants or a lower basal metabolic rate. The paper, published online in the journal Royal Society Biology Letters concludes the olm raises questions about agiing and “appears as a promising model” to study mechanisms preventing aging processes in vertebrates. Citation: Scientists study why the blind salamander lives so long (2010, July 22) retrieved 18 August 2019 from https://phys.org/news/2010-07-scientists-salamander.html Explore further (PhysOrg.com) — Scientists have long been intrigued by the longevity of a tiny amphibian known as the blind salamander, but it now seems it may live a long time because it basically has no life. Proteus anguinus. Image crecit: CNRSlast_img read more

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Scientists suggest spacetime has no time dimension

first_imgScientists propose that clocks measure the numerical order of material change in space, where space is a fundamental entity; time itself is not a fundamental physical entity. Image credit: Wikimedia Commons. (PhysOrg.com) — The concept of time as a way to measure the duration of events is not only deeply intuitive, it also plays an important role in our mathematical descriptions of physical systems. For instance, we define an object’s speed as its displacement per a given time. But some researchers theorize that this Newtonian idea of time as an absolute quantity that flows on its own, along with the idea that time is the fourth dimension of spacetime, are incorrect. They propose to replace these concepts of time with a view that corresponds more accurately to the physical world: time as a measure of the numerical order of change. © 2010 PhysOrg.com In the future, the scientists plan to investigate the possibility that quantum space has three dimensions of space, as Sorli explained.“The idea of time being the fourth dimension of space did not bring much progress in physics and is in contradiction with the formalism of special relativity,” he said. “We are now developing a formalism of 3D quantum space based on Planck work. It seems that the universe is 3D from the macro to the micro level to the Planck volume, which per formalism is 3D. In this 3D space there is no ‘length contraction,’ there is no ‘time dilation.’ What really exists is that the velocity of material change is ‘relative’ in the Einstein sense.”Numerical order in spaceThe researchers give an example of this concept of time by imagining a photon that is moving between two points in space. The distance between these two points is composed of Planck distances, each of which is the smallest distance that the photon can move. (The fundamental unit of this motion is Planck time.) When the photon moves a Planck distance, it is moving exclusively in space and not in absolute time, the researchers explain. The photon can be thought of as moving from point 1 to point 2, and its position at point 1 is “before” its position at point 2 in the sense that the number 1 comes before the number 2 in the numerical order. Numerical order is not equivalent to temporal order, i.e., the number 1 does not exist before the number 2 in time, only numerically. As the researchers explain, without using time as the fourth dimension of spacetime, the physical world can be described more accurately. As physicist Enrico Prati noted in a recent study, Hamiltonian dynamics (equations in classical mechanics) is robustly well-defined without the concept of absolute time. Other scientists have pointed out that the mathematical model of spacetime does not correspond to physical reality, and propose that a timeless “state space” provides a more accurate framework.The scientists also investigated the falsifiability of the two notions of time. The concept of time as the fourth dimension of space – as a fundamental physical entity in which an experiment occurs – can be falsified by an experiment in which time does not exist, according to the scientists. An example of an experiment in which time is not present as a fundamental entity is the Coulomb experiment; mathematically, this experiment takes place only in space. On the other hand, in the concept of time as a numerical order of change taking place in space, space is the fundamental physical entity in which a given experiment occurs. Although this concept could be falsified by an experiment in which time (measured by clocks) is not the numerical order of material change, such an experiment is not yet known.“Newton theory on absolute time is not falsifiable, you cannot prove it or disprove it, you have to believe in it,” Sorli said. “The theory of time as the fourth dimension of space is falsifiable and in our last article we prove there are strong indications that it might be wrong. On the basis of experimental data, time is what we measure with clocks: with clocks we measure the numerical order of material change, i.e., motion in space.”How it makes senseIn addition to providing a more accurate description of the nature of physical reality, the concept of time as a numerical order of change can also resolve Zeno’s paradox of Achilles and the Tortoise. In this paradox, the faster Achilles gives the Tortoise a head start in the race. But although Achilles can run 10 times faster than the Tortoise, he can never surpass the Tortoise because, for every distance unit that Achilles runs, the Tortoise also runs 1/10 that distance. So whenever Achilles reaches a point where the Tortoise has been, the Tortoise has also moved slightly ahead. Although the conclusion that Achilles can never surpass the Tortoise is obviously false, there are many different proposed explanations for why the argument is flawed.Here, the researchers explain that the paradox can be resolved by redefining velocity, so that the velocity of both runners is derived from the numerical order of their motion, rather than their displacement and direction in time. From this perspective, Achilles and the Tortoise move through space only, and Achilles can surpass Tortoise in space, though not in absolute time.The researchers also briefly examine how this new view of time fits with how we intuitively perceive time. Many neurological studies have confirmed that we do have a sense of past, present, and future. This evidence has led to the proposal that the brain represents time with an internal “clock” that emits neural ticks (the “pacemaker-accumulator” model). However, some recent studies have challenged this traditional view, and suggest that the brain represents time in a spatially distributed way, by detecting the activation of different neural populations. Although we perceive events as occurring in the past, present, or future, these concepts may just be part of a psychological frame in which we experience material changes in space.Finally, the researchers explain that this view of time does not look encouraging for time travelers.“In our view, time travel into the past and future are not possible,” Sorli said. “One can travel in space only, and time is a numerical order of his motion.” Citation: Scientists suggest spacetime has no time dimension (2011, April 25) retrieved 18 August 2019 from https://phys.org/news/2011-04-scientists-spacetime-dimension.html More information: Physicists investigate lower dimensions of the universe This document is subject to copyright. Apart from any fair dealing for the purpose of private study or research, no part may be reproduced without the written permission. The content is provided for information purposes only. In two recent papers (one published and one to be published) in Physics Essays, Amrit Sorli, Davide Fiscaletti, and Dusan Klinar from the Scientific Research Centre Bistra in Ptuj, Slovenia, have described in more detail what this means. No time dimensionThey begin by explaining how we usually assume that time is an absolute physical quantity that plays the role of the independent variable (time, t, is often the x-axis on graphs that show the evolution of a physical system). But, as they note, we never really measure t. What we do measure is an object’s frequency, speed, etc. In other words, what experimentally exists are the motion of an object and the tick of a clock, and we compare the object’s motion to the tick of a clock to measure the object’s frequency, speed, etc. By itself, t has only a mathematical value, and no primary physical existence.This view doesn’t mean that time does not exist, but that time has more to do with space than with the idea of an absolute time. So while 4D spacetime is usually considered to consist of three dimensions of space and one dimension of time, the researchers’ view suggests that it’s more correct to imagine spacetime as four dimensions of space. In other words, as they say, the universe is “timeless.”“Minkowski space is not 3D + T, it is 4D,” the scientists write in their most recent paper. “The point of view which considers time to be a physical entity in which material changes occur is here replaced with a more convenient view of time being merely the numerical order of material change. This view corresponds better to the physical world and has more explanatory power in describing immediate physical phenomena: gravity, electrostatic interaction, information transfer by EPR experiment are physical phenomena carried directly by the space in which physical phenomena occur.”As the scientists added, the roots of this idea come from Einstein himself.“Einstein said, ‘Time has no independent existence apart from the order of events by which we measure it,’” Sorli told PhysOrg.com. “Time is exactly the order of events: this is my conclusion.” Explore further Amrit Sorli, Davide Fiscaletti, and Dusan Klinar. “Replacing time with numerical order of material change resolves Zeno problems of motion.” Physics Essays, 24, 1 (2011). DOI: 10.4006/1.3525416Amrit Sorli, Dusan Klinar, and Davide Fiscaletti. “New Insights into the Special Theory of Relativity.” Physics Essays 24, 2 (2011). To be published.last_img read more

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Researchers show bacteria use natural materials to transfer electrons

first_imgGeobacter grows on an electrode. The bacteria feeds on electrons, enabling it to “breathe in” carbon dioxide and “exhale” fuels. Image credit: UMass, Geobacter.org. This document is subject to copyright. Apart from any fair dealing for the purpose of private study or research, no part may be reproduced without the written permission. The content is provided for information purposes only. Researchers discover how bacteria can immobilize uranium Journal information: Proceedings of the National Academy of Sciences Explore further Citation: Researchers show bacteria use natural materials to transfer electrons (2012, June 6) retrieved 18 August 2019 from https://phys.org/news/2012-06-bacteria-natural-materials-electrons.htmlcenter_img Scientists have speculated since the 1960’s that microorganisms are able to communicate with one another or other organisms though conductive material in soil, but until now, the idea was just theory. And just two years ago, researches in Denmark had found that microorganisms living in the sediment at the bottom of sea were somehow able to exchange electrons with those that live on the surface, which resulted in oxygen being made available for those in the sediment enabling them to survive.In this newest research the team added two types of bacteria, Geobacter sulfurreducens and Thiobacillus denitrificans, to a sample of soil and then added acetate and nitrate, the food that the two microorganisms normally eat. But neither would do so. To help them out, the team mixed in the electrically conducting mineral magnetite. That spurred both into action. The idea is that neither of the two types of bacteria can eat without the ability to transfer electrons from one to another and magnetite is the conduit they use to accomplish that feat. To make sure their observations were correct, the team tried using the poor conductor rusted red iron and found the bacteria slowed their eating as a result. And when a non-conductor was mixed in instead, both stopped eating altogether.The team speculates that based on their results it’s likely that many microorganisms communicate by passing electrons through soil, though one small detail still needs to be worked out. How can they rely on the conductive material to be spaced just right in the soil to allow for the passing of electrons? At this time no one is really sure, but some have suggested that it’s possible that the bacteria may actually cause so-called electrical grids to be built to allow them to communicate, though thus far there is no evidence to support the theory, intriguing as it may be. © 2012 Phys.Org (Phys.org) — For years scientists have known that plants and animals transfer electrons between cells and because of that are able to consume food and use it to gain energy. They’ve also known that some microorganisms are able to transfer electrons between themselves and other organisms that are some distance apart. What’s not been known is how they do that. Now, a new study by a team of Japanese researchers has found that at least some bacteria use natural elements in the soil to transfer electrons and thus enable their survival. In their paper published in the Proceedings of the National Academy of Sciences, they describe how they recreated the process by which bacteria communicate over distances in their lab by adding magnetite to the soil which caused previously non-communicating bacteria to begin interacting over a small distance. More information: Microbial interspecies electron transfer via electric currents through conductive minerals, PNAS, Published online before print June 4, 2012, doi: 10.1073/pnas.1117592109AbstractIn anaerobic biota, reducing equivalents (electrons) are transferred between different species of microbes [interspecies electron transfer (IET)], establishing the basis of cooperative behaviors and community functions. IET mechanisms described so far are based on diffusion of redox chemical species and/or direct contact in cell aggregates. Here, we show another possibility that IET also occurs via electric currents through natural conductive minerals. Our investigation revealed that electrically conductive magnetite nanoparticles facilitated IET from Geobacter sulfurreducens to Thiobacillus denitrificans, accomplishing acetate oxidation coupled to nitrate reduction. This two-species cooperative catabolism also occurred, albeit one order of magnitude slower, in the presence of Fe ions that worked as diffusive redox species. Semiconductive and insulating iron-oxide nanoparticles did not accelerate the cooperative catabolism. Our results suggest that microbes use conductive mineral particles as conduits of electrons, resulting in efficient IET and cooperative catabolism. Furthermore, such natural mineral conduits are considered to provide ecological advantages for users, because their investments in IET can be reduced. Given that conductive minerals are ubiquitously and abundantly present in nature, electric interactions between microbes and conductive minerals may contribute greatly to the coupling of biogeochemical reactions.last_img read more

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MIT team shows system that tracks people through walls

first_imgThe IDG News Service video noted a few drawbacks in the system as-is. It can only track one person at a time; the rest of the area needs to be completely clear of movement. Another item on the to-do list is to make the system more compact. Zach Kabelac, masters student, said in the IDG News Service video that “We can put a lot more work into miniaturizing the hardware. The antennas don’t need to be as far apart as they are now. We can bring these closer together to the size of a Kinect, possibly smaller—in the process lose a little bit of accuracy but compared to the gains our system provides, it’s minimal.”The group recently filed a patent, although there are no immediate plans for commercialization. © 2013 Phys.org (Phys.org) —A team of researchers at MIT have been working this year on a system that can track people through walls with impressive accuracy using radio waves. The team showed the system earlier this month. IDG News Service made a video of the demo, which took place at MIT’s Computer Science and Artificial Laboratory (CSAIL) in Cambridge, Massachusetts. The system is still in a proof of concept stage but the team spoke with reps from wireless and component companies during an open house recently. The system was developed by Professor and CSAIL Principal Investigator Dina Katabi and PhD student Fadel Adib. The technology uses low-power signals to track human movement and to decipher motions behind walls. Adib said their accuracy is higher than even state of the art Wi-Fi localization. The approach involves three radio antennas—two transmitting and one receiving, pointed at a wall. In the demo, a person walked around the room on the other side of the wall. The system represented that person as a red dot on a computer screen. and could place the person on the other side of the wall n MIT project can track a user with an accuracy of +/- 10 centimeters. Earlier this year, another report from MIT that was following the CSAIL project’s progress, noted that while researchers have long attempted to build a device capable of seeing people through walls, previous efforts involved expensive and bulky radar technology. The system at MIT uses low-cost technology. The goal is to come up with a device that is low-power, portable and simple enough for use to see through walls and closed doors.Possible scenarios making use of such a system include law enforcement, to avoid personnel walking into an ambush; hostage standoffs; emergency responders trying to see through collapsed structures; and gaming. In addition, the system could be put to use for everyday needs in monitoring children and the elderly. More information: people.csail.mit.edu/fadel/wivi/design.htmlwww.itworld.com/hardware/37824 … h-walls-x-ray-vision Low-power Wi-Fi signal tracks movement—even behind walls Explore further Citation: MIT team shows system that tracks people through walls (2013, October 16) retrieved 18 August 2019 from https://phys.org/news/2013-10-mit-team-tracks-people-walls.html This document is subject to copyright. Apart from any fair dealing for the purpose of private study or research, no part may be reproduced without the written permission. The content is provided for information purposes only.last_img read more

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Researchers find storm periodicity in southern oceans

first_imgCredit: Tiago Fioreze / Wikipedia Citation: Researchers find storm periodicity in southern oceans (2014, February 7) retrieved 18 August 2019 from https://phys.org/news/2014-02-storm-periodicity-southern-oceans.html This document is subject to copyright. Apart from any fair dealing for the purpose of private study or research, no part may be reproduced without the written permission. The content is provided for information purposes only. Explore further Future weather conditions are hard to predict due in part to their seemingly random nature, but one part of the world may not be as random as has thought. In this new effort, the research duo pulled out atmospheric data (from balloons, surface temperature readings and satellite observations) relevant to southern hemispheric oceans, covering the past thirty years. In so doing, they focused primarily on circulation of large atmospheric events in the middle latitudes over the southern oceans. That led them to the discovery of a near rhythmic flow of heat as it was carried from the tropical regions into the colder mid-latitudes. That flow, they noted, tended to cause an imbalance in atmospheric conditions that led to the development of storms. It happens, they report, over and over, with storms occurring roughly every 20 to 30 days.Atmospheric scientists have long known about tropic based circulation patterns—so well-known are they that some of them have names, such as the Quasi-Biennial or Madden-Julian Oscillation. What’s surprising is that such circulation patterns are apparently indirectly impacting weather patterns in the mid-latitudes in the south—so much so that the weather there has become periodic as a result. At least as startling, perhaps, is that no one until now has noticed this weather system—at least not in the scientific community—anecdotal evidence suggests sailors have known about it for years.The team used what they had learned to build a computer model to simulate the conditions that were evident in the data record and found the same result, which they suggest means that storms really do follow a periodic pattern in the oceanic part of the Southern Hemisphere—a finding that could prove invaluable for weather forecasters in South America, Africa, Australia or even Antarctica. (Phys.org) —A pair of researchers with the Department of Atmospheric Science at Colorado State University has found that storms in the Southern Hemisphere tend to occur on a 20 to 30 day periodic basis. In their paper published in the journal Science, David Thompson and Elizabeth Barnes describe how they analyzed thirty years of atmospheric data and used it to create a weather model that revealed the periodic behavior of weather patterns in the Southern Hemisphere.center_img Journal information: Science More information: Periodic Variability in the Large-Scale Southern Hemisphere Atmospheric Circulation, Science 7 February 2014: Vol. 343 no. 6171 pp. 641-645. DOI: 10.1126/science.1247660AbstractPeriodic behavior in the climate system has important implications not only for weather prediction but also for understanding and interpreting the physical processes that drive climate variability. Here we demonstrate that the large-scale Southern Hemisphere atmospheric circulation exhibits marked periodicity on time scales of approximately 20 to 30 days. The periodicity is tied to the Southern Hemisphere baroclinic annular mode and emerges in hemispheric-scale averages of the eddy fluxes of heat, the eddy kinetic energy, and precipitation. Observational and theoretical analyses suggest that the oscillation results from feedbacks between the extratropical baroclinicity, the wave fluxes of heat, and radiative damping. The oscillation plays a potentially profound role in driving large-scale climate variability throughout much of the mid-latitude Southern Hemisphere. © 2014 Phys.org Changing atmospheric circulation over North Atlantic less likely to steer Sandy-like storms into the US coastlast_img read more

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Study shows fairy wrens aware that their mating plumage attracts predators

first_imgMale in breeding plumage subspecies cyaneus. Credit: JJ Harrison/Wikipedia A lot of research has been done on male bird plumage and its impact on breeding, but little has been done to learn more about possible side-effects of such plumage displays. In this new effort, the researchers sought to learn more about how sporting bright feathers causes male faerie wrens to alter their behavior due to fear of increased attention from predators.Faerie wrens live in Australia and Tasmania—the natural coloring of both genders is soft brown and white. But just prior to mating season, some of the males shed their feathers and grow new ones that are several shades of blue to replace them. The feathers are quite naturally meant to attract females, but they also make it easier for predators to spot them. To learn more about how growing such plumage impacts male behavior, the researchers recorded predator warning calls by the birds and then played them back as a means of monitoring behavior.Because only some of the males turn blue for mating season, it was possible to compare the behavior of both blue and non-blue males, as well as that of females and younger birds. Also, because the males do not change color every year, it was possible to compare the behavior of males when hearing warning calls during times when they were blue, versus when they were not.The researchers report that males behaved much more cautiously during their blue periods compared to their behavior when they remained brown and compared to other males. They tended to be more sensitive to low-risk calls and responded faster to high-risk calls. They were also more likely to abandon activities they were engaged in prior to hearing a call. The researchers also found that other faerie wrens in the vicinity of the blue-plumed birds were less careful, though it was not clear if was because they felt that a predator would go for the blue bird or if they used the highly sensitive blue birds as sentries. More information: Alexandra McQueen et al. Bright birds are cautious: seasonally conspicuous plumage prompts risk avoidance by male superb fairy-wrens, Proceedings of the Royal Society B: Biological Sciences (2017). DOI: 10.1098/rspb.2017.0446AbstractIncreased predation risk is considered a cost of having conspicuous colours, affecting the anti-predator behaviour of colourful animals. However, this is difficult to test, as individual factors often covary with colour and behaviour. We used alarm call playback and behavioural observations to assess whether individual birds adjust their response to risk according to their plumage colour. Male superb fairy-wrens (Malurus cyaneus) change from a dull brown to conspicuous blue plumage each year, allowing the behaviour of different coloured birds to be compared while controlling for within-individual effects. Because the timing of colour change varies among males, blue and brown birds can also be compared at the same time of year, controlling for seasonal effects on behaviour. While blue, fairy-wrens fled more often in response to alarm calls, and took longer to emerge from cover. Blue fairy-wrens also spent more time foraging in cover and being vigilant. Group members appeared to benefit from the presence of blue males, as they reduced their response to alarms, and allocated less time to sentinel behaviour when a blue male was close by. We suggest that fairy-wrens perceive themselves to be at a higher risk of predation while in conspicuous plumage and adjust their behaviour accordingly.Press release © 2017 Phys.org Citation: Study shows fairy wrens aware that their mating plumage attracts predators (2017, June 28) retrieved 18 August 2019 from https://phys.org/news/2017-06-fairy-wrens-aware-plumage-predators.html Why are so many fairy-wrens blue?center_img Journal information: Proceedings of the Royal Society B Explore further (Phys.org)—A team of researchers with Monash University and Australian National University has found that male superb fairy wrens are aware that their seasonal bright plumage attracts predators and take extra precautions because of it. In their paper published in Proceedings of the Royal Society B, the group describes experiments they carried out with the birds and what they learned about them. This document is subject to copyright. Apart from any fair dealing for the purpose of private study or research, no part may be reproduced without the written permission. The content is provided for information purposes only.last_img read more

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Researchers suggest Little Foot is an entirely new species of early human

first_img © 2018 Science X Network Citation: Researchers suggest ‘Little Foot’ is an entirely new species of early human (2018, December 10) retrieved 18 August 2019 from https://phys.org/news/2018-12-foot-species-early-human.html South African skeleton shows humans learned to walk upright in the trees This document is subject to copyright. Apart from any fair dealing for the purpose of private study or research, no part may be reproduced without the written permission. The content is provided for information purposes only. The curved left forearms bones of the StW 573 Australopithecus skeleton shown with superior toward the top of the image. The ulna (left) is near-lateral view and radius (right) is in anterior view. Credit: Bilateral Asymmetry of the Forearm Bones as Possible Evidence of Antemortem Trauma in the StW 573 Australopithecus Skeleton from Sterkfontein Member 2 (South Africa), The skeleton first became known when Ronald Clarke of the University of Witwatersrand looked through a bone collection back in the 1990s—he came across foot bones that were labeled as monkey bones. After determining that they were not ape, he and colleagues ventured to the Sterkfontein caves near Johannesburg in 1994, where the bones had been found, and began digging. Because of the challenges involved, it took the team approximately 10 years to fully extricate the skeleton from the rock in which it was embedded. It took another 10 years to fully clean and study the skeleton. Four teams with ties to Clarke have written papers describing aspects of the skeleton, all of which conclude that it represents a unique species. Clarke and his team have therefore given it a name: Australopithecus Prometheus. The researchers are offering some details of their findings as their papers make their way first onto bioRxiv, and then presumably into a journal.The researchers report that the skeleton was from an elderly woman with an arm bowed due to injury. They also report that the woman would have stood just over four feet tall and had legs that were longer than her arms—a hallmark of bipedalism. She was also vegetarian. The details regarding the skeletal remains have been released prior to publication because other groups have recently been granted access to the remains, and the original team does not want to be scooped.The researchers have told the press that Little Foot’s face is flatter than the faces of members of A. africanus (which includes Lucy). There are also other differences in skull shape and tooth arrangement and size. They suggest differences in the hip bone alone are enough to support their claim that Little Foot is a new species. More information: Robin Huw Crompton et al. Functional Anatomy, Biomechanical Performance Capabilities and Potential Niche of StW 573: an Australopithecus Skeleton (circa 3.67 Ma) From Sterkfontein Member 2, and its significance for The Last Common Ancestor of the African Apes and for Hominin Origins, (2018). DOI: 10.1101/481556 Ronald J Clarke et al. The skull of StW 573, a 3.67 Ma Australopithecus skeleton from Sterkfontein Caves, South Africa, (2018). DOI: 10.1101/483495 Laurent Bruxelles et al. A multiscale stratigraphic investigation of the context of StW 573 Little Foot and Member 2, Sterkfontein Caves, South Africa, (2018). DOI: 10.1101/482711 A.J. Heile et al. Bilateral Asymmetry of the Forearm Bones as Possible Evidence of Antemortem Trauma in the StW 573 Australopithecus Skeleton from Sterkfontein Member 2 (South Africa), (2018). DOI: 10.1101/486076 Explore further Several teams of researchers have announced that the skeletal remains of a hominin believed to have lived approximately 3.67 million years ago represent a new species of early human. The researchers report that the specimen, known as “Little Foot,” has characteristics that make it unlike any other known species.last_img read more

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Astronomers discover nine new variable stars

first_img Dozens of new variable stars found in a dense globular cluster This document is subject to copyright. Apart from any fair dealing for the purpose of private study or research, no part may be reproduced without the written permission. The content is provided for information purposes only. Explore further A team of astronomers from Chile has detected nine new variable stars in the globular cluster NGC 6652 and its background stream. Six of the newly found stars were classified as eclipsing binaries, one as an SX Phoenicis star, and two remain unclassified. The finding is detailed in a paper published December 10 on arXiv.org. Variable stars could offer important hints into aspects of stellar structure and evolution. They could be also helpful for better understanding of the distance scale of the universe.In particular, studies of variable stars in star clusters are of special interest for astronomers as they have the potential to help identify systematic errors that affect stellar distance indicators. However, although stellar variability in globular clusters (GCs) of the Milky Way galaxy is one of the oldest branches of astronomy, there are still many galactic GCs in which the census of their variable star content is far from complete.One such understudied cluster is NGC 6652, residing some 32,600 light-years away from the Earth and about 8,800 light-years from the center of the Milky Way, in front of the Sagittarius dwarf spheroidal galaxy. It is an old (about 11.7 billion years), fairly metal-rich galactic globular cluster associated either with the Milky Way’s inner halo or the outer parts of the bulge.A group of researchers led by Ricardo Salinas of Gemini Observatory in Chile, has conducted a search for variable stars in NGC 6652 and the background Sagittarius stream. They have analyzed archival data from the Gemini Multiobject Spectrograph (GMOS) at the Gemini South telescope, which resulted in finding nine new variable stars.”We conducted a variable star search on the metal-rich galactic globular cluster NGC 6652 using archival Gemini-S/GMOS data. We report the discovery of nine new variable stars in the NGC 6652 field, of which we classify six as eclipsing binaries and one as an SX Phoenicis star, leaving two variables without classification,” the astronomers wrote in the paper. The newly detected variable stars received provisional designation from V15 to V23. V17 is an SX Phoenicis star, while the classification of V15 and V21 is currently unknown. The most interesting find presented in the paper is V17 – a pulsating blue straggler. It is a member of the Sagittarius stream and has a well-defined period of 0.039 days.In general, SX Phoenicis stars like V17 have spectral types between A2 and F5, vary in magnitude by up to 0.7, and short period pulsation behavior varying on timescales from 0.03 to 0.08 days. All known SX Phoenicis variables in GCs are blue straggler stars as they are more luminous and bluer than stars at the main sequence turnoff point for the cluster.When it comes to the six binaries, V16 was found to be a long-period eclipsing binary, V18 a Beta Lyra-type eclipsing binary, and V19 most likely a W Uma type, although a Beta Lyra membership cannot be excluded. According to the researchers, V20 is also most likely of W Uma type, V22 could be a RGB star in an eclipsing system, while V23 is an eclipsing variable of the Algol type. © 2018 Science X Network Citation: Astronomers discover nine new variable stars (2018, December 19) retrieved 18 August 2019 from https://phys.org/news/2018-12-astronomers-variable-stars.html A finding chart for the discovered variables in the NGC 6652 field, based on a GMOS r image. The position of V14 is also indicated. The fov is 5.5′ ×5.5′ . North is up, East to the left. Credit: Salinas et al., 2018. More information: Ricardo Salinas et al. New variable stars in NGC 6652 and its background Sagittarius stream. arXiv:1812.03605 [astro-ph.SR] arxiv.org/abs/1812.03605last_img read more

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California Says Its Cannabis Revenue Has Falle

first_img by NPR News Bill Chappell 8.23.19 3:58pm California’s cannabis excise tax generated only $74.2 million in the second quarter of 2019, the state says, announcing numbers that are short of projections that were set months ago. It’s the latest sign that the country’s largest marijuana market has struggled to take off since sales of recreational pot became legal last year. The second-quarter figure reflected a gain over the $63.1 million excise revenue from the first three months of 2019. But earlier this year, the results prompted Gov. Gavin Newsom to revise his office’s estimates of how much money the state would net from its cannabis industry.”In January, Gov. Gavin Newsom’s proposed budget forecast $355 million and $514 million in excise tax revenues for fiscal years 2019 and 2020, respectively,” as member station Capital Public Radio reported. In May, Newsom’s budget lowered its expectations for the cannabis excise tax, to $288 million in the current fiscal year and to $359 million in 2020.Compared to other states, California’s legal cannabis market has stumbled rather than soared. When California moved from a loosely regulated medical marijuana system to a fully regulated retail system in 2018, it watched legal sales drop to $2.5 billion, from around $3 billion the year before. “After adjusting for population, the Golden State raised the second-least amount of revenue from cannabis taxes during the second quarter among states with legal sales, ahead of only Massachusetts,” according to the Institute on Taxation and Economic Policy. The result was a departure from the spikes seen in states such as Colorado, Washington and Oregon after those states legalized recreational markets.”What had happened was that those markets typically doubled in the first year,” says Tom Adams, of the cannabis industry research firm BDS Analytics. In those three states, he adds, they “posted 50 to 90 percent compound annual growth for three years straight.”As for what’s holding California back, Adams says licensed stores can be hard to find, because many local areas have refused to allow retailers to open. And then there are the tax and regulatory costs: In addition to requiring wholesale distribution, California imposes a number of levies on the cannabis industry.”It’s typically 9% to 11% retail sales tax” in California, Adams says. But local city and county governments can impose their own taxes on cannabis products, and those rates vary widely.California also imposes a 15% excise tax, along with a cultivation tax of $9.25 that growers must pay for each ounce of dried cannabis flowers. Of the decision to levy a set tax that’s based on weight rather than on a fluctuating market price, Adams says that if “instead of going with a percentage of revenue tax you go with a per ounce tax, that gets painful really quickly.”Confronted with high taxes in the legal market and new requirements for getting an annual medical marijuana card, many cannabis users in California have turned to the illegal market. The number of medicinal customers has shrunk drastically in the past year, Adams notes. And he says the state’s rules about keeping inventories separate for recreational and medicinal sales have either increased costs or prompted some retailers to abandon the medical market altogether.In addition to the state excise tax, California’s cultivation tax pulled in $22.6 million and its state sales tax totaled $47.4 million, for a total cannabis revenue boost of $144.2 million for the second quarter, the California Department of Tax and Fee Administration reported this week. The state’s figures do not include taxes collected at the local level. Despite the market’s challenges, BDS Analytics released a report earlier this month that predicts California’s legal cannabis sales will grow by 23% in 2019 to $3.1 billion, and will rise to $7.2 billion in 2024. But the firm also believes that even five years from now, the illicit market will still account for 53% of all cannabis sales in California. By contrast, the firm says, “States with more supportive regulatory regimes are expecting illicit sales to make up less than 30%” of all sales.Copyright 2019 NPR. To see more, visit NPR. California Says Its Cannabis Revenue Has Fallen Short Of… Elijah Nouvelagelast_img read more

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