Month: August 2019

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first_imgIs an LHC doomsday scenario a groundless fear or a legitimate concern? Image credit: CERN. But, right or wrong, many people continue to voice their concern about the LHC’s potential to produce a worldwide catastrophe. Some of these concerns clearly go overboard, stemmed by fear and ignorance. In the midst of this extremism, is it possible for someone outside the physics community to analyze the LHC’s risk of producing an Earth-swallowing black hole in a rational way?Eric E. Johnson, an assistant professor of law at the University of North Dakota, has undertaken this task from a legal point of view. He has recently published a paper in the Tennessee Law Review in which he investigates how the courts might handle the LHC case and other future cases of largely unprecedented, potentially dangerous sci-fi-like experiments. The 90-page paper is highly readable for non-scientists, and is available at Johnson, who admits that he is “unanxious” about a doomsday scenario, has two reasons for writing the paper: first, to present a kind of case study for debate among lawyers; and second, to prepare to solve such a legal case in real life.“I intend to provide a set of analytical and theoretical tools that are usable in the courts for dealing with this case and cases like it,” Johnson writes. “If litigation over the LHC does not put a judge in the position of saving the world, another case soon might. In a technological age of human-induced climate change, genetic engineering, nanotechnology, artificially intelligent machines, and other potential threats, the odds of the courts confronting a real doomsday scenario in the near future are decidedly non-trivial. If the courts are going to be able to play their role in upholding the rule of law in such super-extreme environments, then the courts need analytical methods that will allow for making fair and principled decisions despite the challenges such cases present.”The ScienceIn his paper, Johnson begins with an overview of the background of the LHC, as well as the lab at which it’s located, the European Organization for Nuclear Research (CERN) in Geneva, Switzerland. This overview is followed by a short history of one of the LHC’s predecessors, the Relativistic Heavy Ion Collider (RHIC) at Brookhaven National Laboratory in Upton, New York, and then a brief explanation of alleged dangers such as strangelets, magnetic monopoles, bosenovae, and vacuum transitions. Regarding the safety of these potential disaster scenarios, CERN’s argument is the same for each of them: high-energy cosmic-ray collisions (which are similar to those produced in particle colliders) have been occurring in Earth’s atmosphere throughout the planet’s history – so anything dangerous that the LHC could create would already have been produced by cosmic rays long ago. The fact that the Earth still exists is living evidence of the safety of these scenarios. Stephen Hawking tours the future of particle physics at CERN Explore further The question of the black hole risk came up recently in 1999, inspiring particle physicists at the RHIC to analyze the possibility. They found that the forces created by modern accelerators were insufficient to create a black hole – at least in a four-dimensional world. Shortly after, physicists found that black holes could be produced if there were extra dimensions, a possibility in some theories. In light of these findings, CERN physicists reexamined the safety issue and found that the LHC would likely produce black holes, but that they would rapidly evaporate due to Hawking radiation.While very few particle physicists have challenged the orthodoxy of Hawking radiation, the theory does have a few outside critics. Johnson highlights a few of these critics, including chaos theoretician Otto Rossler, who calculated that “LHC-produced black holes might grow fast enough that the world might end slightly more than five years after the LHC’s first full-energy collisions.” Although CERN physicists didn’t respond directly to Rossler’s shocking argument, media and citizen inquiries regarding the LHC’s safety prompted CERN to set up the LHC Safety Assessment Group (LSAG).In a paper written in 2008, Mangano (a CERN employee) and Giddings (who accepted a future visiting position at CERN) turned to the cosmic ray argument rather than the Hawking radiation argument, which was becoming less persuasive. However, they found that black holes produced by cosmic rays could potentially slip through the Earth, which is made mostly of empty space, while black holes produced by the LHC could remain in the vicinity for a long time, slowly gaining mass. Looking deeper into the universe, the physicists found that a kind of white dwarf star, eight of which have been observed, could likely hold black holes for a long time, and so their continued existence must serve as living evidence that the LHC is safe.Although Giddings and Mangano concluded that there is no risk of “any significance” from black holes produced by the LHC, Johnson notes that CERN’s Scientific Policy Committee (SPC) took an extra step, announcing to the public that the results excluded “any possibility” of risk. When the Giddings and Mangano paper was posted publicly in 2008, astrophysicist Rainer Plaga wrote an unpublished paper arguing that Giddings and Mangano’s paper did not exclude all possibilities of disaster. In one argument, Plaga showed that, if black holes were smaller than the CERN physicists calculated, they could conceivably sail through white dwarfs as well as the Earth, showing that the white dwarf argument isn’t conclusive.Johnson said that, while researching the subject, he was surprised at the legitimate science controversy surrounding the crazy-sounding idea of black holes destroying the Earth.“Many of the physicists quoted in the media on LHC safety issues seem not to have engaged with the literature in any depth,” Johnson told “Physicists speaking to the public about the black-holes question portray it as a simple matter. It really is not. At the end of the day, the LHC may or may not be safe, but most of the arguments you hear in favor of the collider lack robustness.”The LawComplex disagreements such as these lead to great challenges when it comes to analyzing the risks of science experiments in a court of law. First of all, the only people who have the qualifications to understand the physics are the physicists themselves, which creates an obvious conflict of interest. The problem of insider testimony is just one of the unique problems in this kind of unprecedented case, which Johnson describes as a “jurisprudential singularity.” He explains that the legal problems posed by black holes mirror the problems they create for physics.“Physicists relate that in the vicinity of a gravitational singularity, equations break down, and the known laws of physics seem to fail,” he writes. “With reference to American law, I discuss three lines of legal doctrine that suffer similarly: preliminary-injunction analysis, expert-testimony gatekeeping, and cost-benefit analysis. Developed for a world of automobile accidents, toxic waste, and teratogenic pharmaceuticals, these doctrines all start to break down when confronted with the extreme facts of the black-hole case.”In order to stop the LHC from operating, a plaintiff would likely seek a preliminary injunction against CERN. As Johnson explains, “under American law, a preliminary injunction is a way for a court to order an immediate halt to a specified activity, without the necessity of going through a full course of discovery and trial.” Preliminary injunction requests are used, for example, to stop impending plans to demolish buildings of historical significance and as restraining orders in domestic violence cases. After a preliminary injunction has been issued, the lawsuit would continue with a more comprehensive trial. Eventually, the defendant would either receive a permanent injunction, or the suit would be dismissed and the preliminary injunction removed.Already, several suits to stop the LHC have been initiated by “a colorful assortment of plaintiffs,” but none has been successful, for various reasons. For example, in a Hawaii lawsuit, the issue was considered one of political policy. Also, CERN has signed treaties with its host states, Switzerland and France, that guarantee CERN immunity from legal processes. As Johnson explains, it would not be difficult to get a preliminary injunction if CERN overtly threatened an illegal action, which of course it has not. On the other hand, getting an injunction against a perceived future risk is rare, aside from specific situations, such as domestic violence. A plaintiff would have to show that the defendant, CERN, has been negligent and not done what a reasonable entity would do to protect others from foreseeable risks. Such cases are rare because usually there are laws that explicitly prohibit negligence of various sorts (such as traffic laws to prevent accidents). In the arena of cutting-edge science research, there are no specific laws that CERN has broken because of the uncharted territory. In addition, by performing a cost-benefit analysis using the Hand formula, Johnson shows that the risk of the LHC destroying the world can be calculated to be either infinite or nothing simply by tweaking the inputs just a tiny bit – just like the singularity of a black hole, to further his analogy. This lack of certainty in risk analysis contributes to the difficulty of getting an injunction.A Judge’s ChallengeWhen deciding whether or not to issue an injunction against CERN, Johnson suggests that a judge should perform a meta-analysis of the case, going beyond the current scientific analysis to look at four issues: errors in the scientific theory on which the safety analysis is based, errors in the calculations or assumptions in the safety analysis itself, cognitive biases such as psychological and cultural biases, and non-innocent errors motivated by self-interest.In the last 20 pages of his paper, Johnson provides several examples of these four issues. For instance, he points out how scientists tend to exercise caution when presenting their research and readily admit to its limitations, yet on the issue of LHC safety, CERN seems to show a sense of absolute confidence. Even a relatively small observational error of the eight white dwarfs could undermine the safety argument, Johnson notes, since these eight objects are all that the ultimate conclusion rests upon. Such errors would not be unprecedented in science, as even scientists are subject to human fallibility. Johnson points out that, in 2003, it was found that the two papers written to address safety concerns about a potential strangelet disaster at the RHIC both contained conceptual math errors that affected their conclusions.“Giddings and Mangano conclude that there is no conceivable risk,” Johnson writes. “But it does not follow that LHC risk is zero: An accurate assessment of risk must include the possibility that Giddings and Mangano themselves are mistaken.”Finally, Johnson suggests that the courts should look at the psychological and sociological issues that contribute to the vulnerability of the scientific process. Stopping the LHC now would destroy the investment of billions of dollars and many physicists’ careers. In this sense, an individual physicist is better off concentrating on the science research than getting involved in safety and legal issues.The CERN culture, which consists of thousands of physicists from around the world working together, is a great international collaboration that has pushed science forward. Yet, as Johnson notes, such a group culture also has the tendency to push dissenters to the fringe, and perhaps artificially inflate the certainty of unanimously enforced views. These sociological factors are difficult to acknowledge, since they are at odds with the field of science itself, which attempts to be as objective as possible. Nevertheless, from a judge’s point of view, all humans are subject to the same human law.Scientists have a responsibility to the rest of the world to ensure that their experiments are safe. While scientists are not above the law, the case of the LHC is obviously a unique situation that deserves special treatment – especially since it may be setting a precedent for future cases as scientists continue to make extraordinary advancements. Without offending the profession, the question is fair to ask: what is the best way to continue to make scientific discoveries without risking human life? Is it possible to agree on an accepted level of risk?Or, as Johnson puts it, “Can human law survive in a realm ‘where physical law ends’?” He argues that the courts have the power to perform an in-depth analysis – involving a thorough review of the evidence and gathering testimony from scientists with no personal stake in the LHC – that could provide answers to these questions.“At the end of the day, whether the LHC represents an intolerable danger is, in my view, an open question,” Johnson concludes. “I have not endeavored to provide a definitive answer. But I think the courts should. … Courts must develop tools to deal meaningfully with such complexity. Otherwise, the wildly expanding sphere of human knowledge will overwhelm the institution of the courts and undo the rule of law – just when we need it most.” ( — Just bringing up the topic of the Large Hadron Collider (LHC) creating a black hole that destroys the Earth might seem unscientific and out of place on a science news website. After all, the subject is generally considered to be out of place in the particle physics community, since peer-reviewed studies have shown that there is no significant risk of an LHC doomsday scenario.center_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. More information: Eric E. Johnson. “The Black Hole Case: The Injunction Against the End of the World.” 76 Tennessee Law Review 819 (2009). Also available at Citation: A Lawyer’s View of the Risk of Black Hole Catastrophe at the LHC (2010, January 22) retrieved 18 August 2019 from Copyright 2010 All rights reserved. This material may not be published, broadcast, rewritten or redistributed in whole or part without the express written permission of read more

first_img Samsung Flexible AMOLED Display at CES 2011 According to reports, Samsung’s earliest models, of the inflexible kind, will be covered with a layer of glass that is 0.4mm thick. The panels, compared to current generation panels, will be a thinner 0.6mm — in contrast to the current measurement of 1.8mm thick , but with rigid protective glass on top. Observers say that by manufacturing these screens now, Samsung gains experience in producing them for traditional, rigid devices such as phones and tablets. When OEMs will start thinking about flexible gadgets, Samsung intends to be ready with ample supply.The company has an internal goal to mass-produce truly flexible displays by 2014. Samsung is confident of a coming upswing in demand. Samsung predicts that by 2014, 50 percent of cell phones may carry AMOLED displays and by 2015 it could be the main TV panel technology.Latest developments suggest Samsung strategy regarding the displays are on course. In its quarterly earnings call in October last year, Samsung’s vice president of investor relations, Robert Yi, told an audience of investors and analysts that flexible displays would be introduced in 2012 and that the application “probably will start from the handset side.” According to those close to developments at Samsung, the real deal AMOLED displays with flexible substrates will appear in 2014. The early batch at the least will carry the AMOLED features of being very thin, with one third the thickness of current mobile screens. OLED displays are thinner, more efficient and offer better picture quality than LCD or plasma displays; OLED is a flat light emitting technology made by placing a series of organic thin films between two conductors. OLEDs also can be made to be flexible and transparent. The term AMOLED stands for Active-Matrix Organic Light Emitting Diode, an advanced display technology that is still considered in an embryonic stage. Asia has become the hub of AMOLED display manufacturing activity, with South Korea, Taiwan and China the key players. The United States represents the single largest market for AMOLED displays. Samsung tablet concept shows a see-through, bendable future (w/ video) ( — Samsung is set to begin manufacturing its “Youm” displays which have been generating pre-launch excitement as ultra-thin AMOLED panels that will be bendable, stretchable, rollable and foldable like a piece of paper. Samsung expects to begin production of its 0.6mm Youm displays this quarter, with a goal of seeing the first products with the technology to market by the end of the year. Oddly, though, the displays to roll out this year in the first batch will not have a flexible substrate. They will have a protective glass layer, which in turn will make them unable to take other forms or shapes, the very bend-it, fold-it feature that draws interest at industry shows. Citation: Samsung readies first batch of super-thin bendable AMOLED displays (2012, July 22) retrieved 18 August 2019 from More information: Samsung tablet concept shows a see-through, bendable future (w/ video): … hrough-bendable.html © 2012 Explore further 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

first_img Journal information: Journal of the American Chemical Society The researchers, Darya Asheghali, Pornnipa Vichchulada, and Associate Professor Marcus D. Lay at the University of Georgia in Athens, have published their paper on converting m-SWNTs to s-SWNTs in a recent issue of the Journal of the American Chemical Society.Previous studies have attempted to overcome the problem of m-SWNTs by using methods that are often complex and expensive. Some approaches involve using specialized SWNT growth methods that select for s-SWNTs, while other approaches involve post-growth solution processing to remove m-SWNTs.The approach proposed in the new study could provide a simpler solution to obtain large amounts of s-SWNTs. After growing the SWNTs using a conventional bulk growth method, the researchers deposited sub-10-nm copper oxide nanoparticles on all of the nanotubes, both metallic and semiconducting. This single step converts the m-SWNTs into s-SWNTs and also improves the electric properties of the original s-SWNTs.When the researchers incorporated these decorated s-SWNTs into transistors, they found that the transistors’ on/off current ratios increased from about 21 to 4300, representing a 205-fold improvement. The reason that the nanoparticles have this effect is because of the way they change the SWNTs’ band gaps. Since a band gap is the energy range in a material where electrons cannot exist, generally a large band gap corresponds to low electrical conductivity, and vice versa. Typically, insulators have large band gaps, semiconductors have smaller band gaps, and conductors have very small or no band gaps. In the current study, the m-SWNTs originally have no band gap, making them good conductors. Although high conductivity is good when transistors are in the on state (when electrons flow), it is a liability in the off state (where electrons don’t flow). Being highly conductive, the m-SWNTs leak a lot of current in the off state. As the researchers demonstrate here, the copper oxide nanoparticles can open up a band gap in the m-SWNTs, which restricts the current flow and greatly reduces the leakage current when the transistor is in the off state. Now that the m-SWNTs have a band gap, they are by definition s-SWNTs. The nanoparticles also increase the band gaps of the s-SWNTs, which improves both their uniformity and current efficiency. 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. Citation: Metallic-to-semiconducting nanotube conversion greatly improves transistor performance (2013, May 28) retrieved 18 August 2019 from © 2013 All rights reserved. Scientists reach the ultimate goal: Controlling chirality in carbon nanotubes ( —Future transistors made of semiconducting single-walled carbon nanotubes (s-SWNTs) have the potential to perform much better than today’s transistors. However, when SWNTs are grown in bulk, only about two-thirds of them are semiconducting, while the other one-third are metallic (m-SWNTs). Since m-SWNTs have a higher conductivity than s-SWNTs, their presence allows current leakage in a transistor’s off state, which greatly decreases the transistor’s on/off current ratio and overall performance. In a new study, scientists have demonstrated that simply decorating the m-SWNTs with copper oxide nanoparticles can convert them into s-SWNTs, resulting in a 205-fold increase in a transistor’s on/off current ratio. The researchers explain that the copper oxide nanoparticles create/increase these band gaps by withdrawing electron density from the SWNTs at the point of contact. In a sense, the nanoparticles act like tiny valves along a wire that increase the SWNTs’ sensitivity to gate voltages at certain points, changing the conductivity of the SWNTs overall.Although the researchers describe the effect as a conversion of metallic SWNTs to semiconducting SWNTs, they also clarify that, when it comes down to it, m-SWNTs are not true metals. Instead, they should be considered semimetals or zero band gap semiconductors because true metals could not be made sensitive to the gate voltage. Graphene also falls into this category of semimetals. However, it is more complicated to open a band gap in graphene because graphene is a 2-D material. The researchers explain that the 1-D nature of SWNTs simplifies the process of band gap tuning by allowing the nanoparticles to act like valves on a wire and locally halt electron transport. This approach cannot carry over to planar graphene due do its different geometry.This relatively simple method of using nanoparticles to convert m-SWNTs into s-SWNTs, and the significant performance improvement that results, has great potential to further the development of SWNT-based transistors in the future, as well as carry over to other areas.”The ability to open a bandgap in graphite-based semiconductors like SWNTs and graphene will have applications in sensors and energy conversion,” Lay told for SWNT field-effect transistors (FETs), Lay explained that other challenges remain before they can become commercially widespread.”The biggest problem facing SWNT FETs is the dearth of purification and suspension formation methods that separate the high aspect ratio SWNTs needed for structural and electronic applications from the soot and catalyst particles that make up about 50% of SWNT samples with common bulk growth methods,” he said. “Another major roadblock is the lack of deposition methods that allow control over the density and alignment of SWNTs.”Lay and his group have contributed significantly to these two areas in another recent study1. When copper nanoparticles are deposited on SWNT networks (left: aligned network; right: crossbar network), the nanoparticles create band gaps in the metallic SWNTs, which decreases leakage current and improves a transistor’s on/off ratio. Credit: D. Asheghali, et al. Explore further More information: D. Asheghali, P. Vichchulada, and M. D. Lay. “Conversion of Metallic Single-Walled Carbon Nanotube Networks to Semiconducting through Electrochemical Ornamentation.” J. Am. Chem. Soc., 2013, 135 (20), 7511–7522. DOI: 10.1021/ja311721gNote: 1 N. P. Bhatt, P. Vichchulada, and M. D. Lay. “Bulk Purification and Deposition Methods for Selective Enrichment in High Aspect Ratio Single-Walled Carbon Nanotubes.” J. Am. Chem. Soc., 134 (2012) 9352-9361, DOI: 10.1021/ja302136xlast_img read more

first_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. Journal information: Proceedings of the Royal Society B Explore further Footage of the Grimalditeuthis bonplandi that was observed at 1000 m depth in the Monterey Submarine Canyon, California, September 25, 2005. (1) When first encountered, the squid was maintaining its position in the water column, and gently undulating the primary fins. (2) The flapping of the club’s trabecular protective membranes move the tentacle. The resemblance of this movement to small organisms may be used to lure prey. (3) A presumed response to disturbance was observed: the squid is slowly swimming backward, when the distal portion of arms I-III are rapidly retracted toward the head and curl into spirals, while the fourth arms remain straight supporting the tentacle, and the squid swims forward toward the arms, enveloping the tentacle with the arms within the brachial crown. (4) A close-up of the head, visceral mass, and tail; the eye-stripe was maintained throughout the entire observation. Credit: Monterey Bay Aquarium Research Institute After analyzing all the video, the researchers on this new effort suggest that the squid uses its tentacle as a lure, casting it about in hopes of attracting the attention of prey. The lure, or club as it’s called, would be the envy of human fishermen as it has thin membranes on its sides that can be manipulated to allow for controlling where it goes. The researchers believe the squid captures the attention of other organisms in the nearby water with its movements, causing some of them to turn on their bioluminescence, which allows the squid to see and perhaps grab prey with its “arms.” It’s also possible, they suggest, that the movement of the club causes vibrations that attract small prey. Citation: ROV video offers clues on how rare squid catches prey (2013, August 28) retrieved 18 August 2019 from Two Grimalditeuthis bonplandi specimens observed in the Gulf of Mexico by ROVs used in the offshore oil industry. The first specimen ‘swims out’ both tentacles by what appears to be the undulating movements of the tentacular clubs. The second specimen has only one tentacle stalk and maneuvers the tentacle club in a way that suggests mimicry of the movements of another organism. Credit: Monterey Bay Aquarium Research Institute Most squid catch prey by extending tentacles with suckers or hooks on them and grabbing what they’re after—G bonplandi can’t do that because it’s single tentacle is too thin and doesn’t have either suckers or hooks—or any other tools for grabbing anything. For that reason, researchers have been mystified for years regarding how it catches prey. Observing the squid has been difficult—they live at depths greater than 1000 meters where it’s pitch black dark. Until 2005, no one had ever captured one on video before, much less seen it in person in its native habitat—prior to that marine biologists only knew about its existence because specimens had been found in the bellies of fish.Since 2005, other video cameras aboard ROVs or affixed to oil platforms have also captured video of the mysterious squid. Unfortunately none of the video shows the squid actually capturing and eating something. But the video does offer tantalizing clues. Study shows one kind of squid can jettison parts of its arm (w/ Video) More information: First in situ observations of the deep-sea squid Grimalditeuthis bonplandi reveal unique use of tentacles, Published 28 August 2013 DOI: 10.1098/rspb.2013.1463AbstractThe deep-sea squid Grimalditeuthis bonplandi has tentacles unique among known squids. The elastic stalk is extremely thin and fragile, whereas the clubs bear no suckers, hooks or photophores. It is unknown whether and how these tentacles are used in prey capture and handling. We present, to our knowledge, the first in situ observations of this species obtained by remotely operated vehicles (ROVs) in the Atlantic and North Pacific. Unexpectedly, G. bonplandi is unable to rapidly extend and retract the tentacle stalk as do other squids, but instead manoeuvres the tentacles by undulation and flapping of the clubs’ trabecular protective membranes. These tentacle club movements superficially resemble the movements of small marine organisms and suggest the possibility that G. bonplandi uses aggressive mimicry by the tentacle clubs to lure prey, which we find to consist of crustaceans and cephalopods. In the darkness of the meso- and bathypelagic zones the flapping and undulatory movements of the tentacle may: (i) stimulate bioluminescence in the surrounding water, (ii) create low-frequency vibrations and/or (iii) produce a hydrodynamic wake. Potential prey of G. bonplandi may be attracted to one or more of these as signals. This singular use of the tentacle adds to the diverse foraging and feeding strategies known in deep-sea cephalopods. ( —Video captured by a camera aboard a Remotely Operated Vehicle (ROV) off the coast of southern California is offering scientists clues to help explain how the rare squid Grimalditeuthis bonplandi, manages to catch prey without benefit of suckers or hooks. The research team behind the project (with the Monterey Bay Aquarium Research Institute) has published a paper in Proceedings of the Royal Society B describing their findings and offering a perspective on how the squid might use its unique appendage to capture prey. © 2013 Phys.orglast_img read more

first_img Cosmologists weigh cosmic filaments and voids 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. Tangled web. A simulation of gravitationally interacting dark matter particles in the Universe shows the stringy nature of dark matter, peppered with voids, over the largest distance scales. Credit: N. Hamaus/Paris Inst. of Astrophys. & M. Warren/Los Alamos National Lab, via Physics More information: Universal Density Profile for Cosmic Voids, Phys. Rev. Lett. 112, 251302 – Published 27 June 2014: … ysRevLett.112.251302 . On Arxiv: present a simple empirical function for the average density profile of cosmic voids, identified via the watershed technique in ΛCDM N-body simulations. This function is universal across void size and redshift, accurately describing a large radial range of scales around void centers with only two free parameters. In analogy to halo density profiles, these parameters describe the scale radius and the central density of voids. While we initially start with a more general four-parameter model, we find two of its parameters to be redundant, as they follow linear trends with the scale radius in two distinct regimes of the void sample, separated by its compensation scale. Assuming linear theory, we derive an analytic formula for the velocity profile of voids and find an excellent agreement with the numerical data as well. In our companion paper [Sutter et al., arXiv:1309.5087 [Mon. Not. R. Astron. Soc. (to be published)]], the presented density profile is shown to be universal even across tracer type, properly describing voids defined in halo and galaxy distributions of varying sparsity, allowing us to relate various void populations by simple rescalings. This provides a powerful framework to match theory and simulations with observational data, opening up promising perspectives to constrain competing models of cosmology and gravity. , arXiv Explore further Journal information: Physical Review Letters Scientists still don’t know much about dark matter—it’s believed to make up most of the known universe (as evidenced by gravitational studies) and doesn’t interact much with parts of the universe we can see, which of course, includes light. To gain a better understanding of it, researchers have been creating computer simulations based on what is observable. Such simulations in the past have shown that dark matter is not uniform, in fact, if we could see it, it would look a lot like the inside of bones—lots of air pockets (voids) with boundary material between them. The simulations indicate that the voids in dark matter form as dark matter akin to a gas, collapses under its own gravity into sheets or filaments that form the boundary between the voids. They also have shown that there appears to be more void, than boundary. Some theories suggest that such structures gave rise to the parts of the universe we are able to see. In this new effort, the research trio has created a new simulation that provides a better perspective on the size and shapes of the voids—focusing specifically on density profiles. Their simulation excluded matter that can be seen but did include dark energy.The new simulation showed voids of various sizes and shapes as has been seen with other simulations—what was new with this simulation was that the team showed that the average density of dark matter reached its maximum in the walls that formed the borders between the voids. They also found that the spherical densities believed to exist at the center of the voids, applies not only to voids of all shapes and sizes, but to those that existed in earlier cosmic history. Interestingly, the researchers found they could fit the profiles empirically using just two parameters in a single formula. © 2014 ( —Three physicists affiliated with several universities in the U.S. and France have built a computer simulation of the bubble-like voids that exist in dark matter which offers better density information. In their paper published in the journal Physical Review Letters, the researchers describe how their simulation showed that such voids have a wide range of sizes and ages with highest densities occurring in boundary areas. Citation: Trio of physicists create computer simulation of dark matter using an empirical function (2014, July 3) retrieved 18 August 2019 from read more

first_img UW fusion reactor concept could be cheaper than coal The old promise of Atoms for Peace was a noble one, but the technology wasn’t right for it. “We can achieve that grand vision and bring clean power to people. The true Atomic Age can start,” he said.Lockheed defines fusion as “the process by which a gas is heated up and separated into its ions and electrons. When the ions get hot enough, they can overcome their mutual repulsion and collide, fusing together. When this happens, they release a lot of energy – about one million times more powerful than a chemical reaction and 3-4 times more powerful than a fission reaction.” A reactor small enough to fit on a truck could provide enough power for a small city of up to 100,000 people. In a discussion of the Skunk Works effort in Aviation Week, Lockheed’s McGuire spoke about the company’s interest in attracting interest in the project. “One of the reasons we are becoming more vocal with our project is that we are building up our team as we start to tackle the other big problems. We need help and we want other people involved. It’s a global enterprise, and we are happy to be leaders in it,” he said. “We have a long ways to go, and there are lots of challenges, but we have a path to do it and a community of fusion researchers and national labs. There’s a collaborative atmosphere and we have got some really good feedback so far.” Lockheed Martin aims to get at a prototype in five years. According to the Aviation Week report, the prototype would demonstrate ignition conditions and the ability to run for upward of 10 sec. in a steady state after the injectors, used to ignite the plasma, are turned off. It would not be at full power like a working concept reactor, “but basically just showing that all the physics works,” McGuire said. © 2014 Tech Xplore Explore further Lockheed Martin is making news this week with declarations about putting the Atomic Age on Restart and advancing in the realm of energy. “We are on the fast track to developing compact nuclear fusion reactors to serve the world’s ever-growing energy needs.”center_img The company’s Skunk Works has provided new details to the public about its work in compact fusion. “At Lockheed Martin Skunk Works, we’re making advancements in the development of fusion energy, the ultimate form of renewable power. Our scientists and engineers are looking at the biggest natural fusion reactor for inspiration – the sun. By containing the power of the sun in a small magnetic bottle, we are on the fast track to developing compact fusion reactors to serve the world’s ever-growing energy needs.” Thomas McGuire, compact fusion project lead, said they think they can get to a prototype in about five years. “That’s what we are doing here; we are testing the concept out.” He said, 50 years ago when people were “super-excited” about nuclear power, “we tried putting it on everything,” including airplanes. He said some big operational issues prevented widespread use. “Fusion is a much safer option,” he stated. The next generation of airplanes not relying on fuel can just stay aloft—with unlimited range, unlimited endurance. That’s what nuclear fusion can do for an airplane. Citation: Lockheed Martin pursues compact fusion reactor concept (2014, October 16) retrieved 18 August 2019 from 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

first_imgSchematic representation of a double spin domain system coupled to a single reservoir. Here we denote the first spin domain containing N1 spins as D1 where the spins are shown as red arrows, the second spin domain 2 with N2 spins is labelled as D2 with the spins represented by the blue arrows. In both domains, each spin couples with the bosonic reservoir (at temperature T ) with the coupling constant g. Credit: arXiv:1612.08963 [quant-ph] Citation: When collective spins in a double domain system relax towards a negative-temperature state (2018, February 16) retrieved 18 August 2019 from The concept of temperature has evolved over a very long period of time, from descriptions of simple sensations to theoretical states of physical systems. In their paper, the researchers with this new effort describe their investigation of relaxation in dual collective spins in a double domain system and some configurations that can result under certain extreme circumstances. Of particular interest are situations involving spin domains in antiparallel configurations, which, when unbalanced, can wind up relaxing toward a negative temperature state. At first glance, such an occurrence would seem impossible, because it suggests there is a circumstance in which some bit of material could be cooled below absolute zero, which, of course, goes against current understanding—but theory suggests it is possible.The idea of a negative temperature state is used by the researchers as an explanation of an occurrence in the real world—population inversion, in which atoms are pushed from a lower energy level to a higher energy level and are then allowed to fall back, resulting in light emission. This is how laser pointers work. When physicists discovered such a property was possible, they took another look at spin, which gives atoms their magnetic properties, and found that spin systems could be coaxed into behaving in more ways than was thought possible—some have even been found to become inverted, which could lead to a system that flows naturally upward in energy levels. In this new effort, the researchers report the possibility of pockets of atoms, two in this case, to have spins that share a reservoir, and which have a fixed temperature. When the two pockets are the same size, the math showed, half of the spins wind up in a higher state, and the other half in the lower state. But when the pockets are different sizes, the spins wind up flowing toward the higher state, making one pocket more inverted than the other, leading to the idea of negative temperatures. Explore further Researchers observe dynamical quantum phase transitions in an interacting many-body system 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. More information: Yusuke Hama et al. Relaxation to Negative Temperatures in Double Domain Systems, Physical Review Letters (2018). DOI: 10.1103/PhysRevLett.120.060403 , On Arxiv: engineering of quantum systems and their environments has led to our ability now to design composite or complex systems with the properties one desires. In fact, this allows us to couple two or more distinct systems to the same environment where potentially unusual behavior and dynamics can be exhibited. In this Letter we investigate the relaxation of two giant spins or collective spin ensembles individually coupled to the same reservoir. We find that, depending on the configuration of the two individual spin ensembles, the steady state of the composite system does not necessarily reach the ground state of the individual systems, unlike what one would expect for independent environments. Further, when the size of one individual spin ensemble is much larger than the second, collective relaxation can drive the second system to an excited steady state even when it starts in the ground state; that is, the second spin ensemble relaxes towards a negative-temperature steady state. © 2018 Journal information: Physical Review Letters A team of researchers from several institutions in Japan has described a physical system that can be described as existing above “absolute hot” and also below absolute zero. In their paper published in the journal Physical Review Letters, the group outlines their ideas on collective spins in double domain systems and the interesting situations that can occur within them. , arXivlast_img read more

first_img Partial baboon skeleton from Misgrot Cave, South Africa. This is one of the comparative assemblages the authors used in the analysis. Credit: PNAS Explore further More information: Charles P. Egeland et al. Hominin skeletal part abundances and claims of deliberate disposal of corpses in the Middle Pleistocene, Proceedings of the National Academy of Sciences (2018). DOI: 10.1073/pnas.1718678115AbstractHumans are set apart from other organisms by the realization of their own mortality. Thus, determining the prehistoric emergence of this capacity is of significant interest to understanding the uniqueness of the human animal. Tracing that capacity chronologically is possible through archaeological investigations that focus on physical markers that reflect “mortality salience.” Among these markers is the deliberate and culturally mediated disposal of corpses. Some Neandertal bone assemblages are among the earliest reasonable claims for the deliberate disposal of hominins, but even these are vigorously debated. More dramatic assertions center on the Middle Pleistocene sites of Sima de los Huesos (SH, Spain) and the Dinaledi Chamber (DC, South Africa), where the remains of multiple hominin individuals were found in deep caves, and under reported taphonomic circumstances that seem to discount the possibility that nonhominin actors and processes contributed to their formation. These claims, with significant implications for charting the evolution of the “human condition,” deserve scrutiny. We test these assertions through machine-learning analyses of hominin skeletal part representation in the SH and DC assemblages. Our results indicate that nonanthropogenic agents and abiotic processes cannot yet be ruled out as significant contributors to the ultimate condition of both collections. This finding does not falsify hypotheses of deliberate disposal for the SH and DC corpses, but does indicate that the data also support partially or completely nonanthropogenic formational histories. © 2018 Study shows changes in anatomy would have made walking easier without reducing muscles for climbing in early hominins An international team of researchers has used a machine learning algorithm to assess whether hominin bones found in caves were placed there as part of a burial service by early human ancestors. In their paper published in Proceedings of the National Academy of Sciences, the group describes the factors they fed into the algorithm, and what it revealed. The researchers report that the algorithm assigned both sites to scavenged corpses, which suggests that the bones made their way into the caves via carrion animals carrying them to feed in relative peace. They note that the algorithm did not rule out the possibility of early hominins conducting burial services in general, just in these two cases.The findings by the team will not settle the debate, of course. Research surrounding the remains in the two caves will undoubtedly continue, with each side using evidence, such as the learning algorithm, to bolster their case.last_img read more

first_imgA pair of researchers affiliated with Duke University and the Max Planck Institute for Evolutionary Anthropology has found that great apes tend to bond with one another when they watch a video together. In their paper published in Proceedings of the Royal Society B, Wouter Wolf and Michael Tomasello describe their work involving studying chimpanzees and bonobos as they watched videos together and how they behaved afterward. © 2019 Science X Network Citation: Great apes found to bond when watching videos together (2019, July 18) retrieved 18 August 2019 from Most people have experienced the feeling of bonding with another person, or even several people, when watching a movie or TV show together. Until now, behavioral scientists have believed such feelings were restricted to humans. In this new effort, Wolf and Tomasello have shown that great apes have similar experiences.The experiments involved seating pairs of chimps together in front of a television so that they could watch a video, and the researchers took measurements of bonding-type behavior after the video was over. They then compared the behavior they observed with a control group. They report that chimps that watched the videos together engaged in more bonding-type behaviors.The videos watched by the chimps were of other chimps engaging in various activities—prior research had shown it was their favorite subject. And the chimps were encouraged to remain in place watching the video by feeding them grape juice. Bonding-type interactions were described as touching, how long they stayed in proximity with one another and how much they paid attention to one another. The researchers also used eye-tracking systems to show that the chimps were actually watching the videos. The researchers also paired up bonobos in the same fashion, and also human-chimp pairs. They report that in all instances, increased bonding was observed for those participating in the shared social events.The researchers suggest their results show that great apes are capable of social bonding when participating in shared events. They suggest that such types of social bonding have deeper evolutionary roots than has been realized. They also suggest that their findings hint at what is lost as humans cease participating in shared social events, preferring instead to engage privately in social media. Journal information: Proceedings of the Royal Society B 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.center_img More information: Wouter Wolf et al. Visually attending to a video together facilitates great ape social closeness, Proceedings of the Royal Society B: Biological Sciences (2019). DOI: 10.1098/rspb.2019.0488 Explore further Credit: CC0 Public Domain Bonobos found to focus more on feel-good imagery than danger or aggressionlast_img read more