Chain letters reveal surprising circulation patterns

first_img 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. The chain e-mail originated sometime in 2002, and claimed to be a petition to organize opposition to the impending US-Iraq war. Tens of thousands of people signed their names to several hundred copies of the petition, with some copies appearing on Web archives. Like most Internet chain letters, the petition had its origins in a hoax, but its widespread dissemination is one of the few instances of a single piece of traceable information spreading on a global scale.“Given the many ways in which information, news, and new ideas are constantly spreading through our social networks, it’s surprising how difficult it is to collect data on the ways in which this spreading happens,” researchers David Liben-Nowell and Jon Kleinberg told PhysOrg.com. “Data from chain-letter petitions lets us look at processes that are otherwise essentially invisible, and begin to formulate theories for the patterns we observe.”Liben-Nowell and Kleinberg are computer scientists from Carleton College and Cornell University, respectively. The duo used online search engines to collect copies of the signed petitions that were posted on numerous Web sites. When they analyzed the 20,000 names on the 637 lists they found, and removed various “mutations,” they discovered some surprising patterns. Contrary to predictions that large-scale information spreads exponentially, like an explosive epidemic, the researchers found that the letter did not reach a large number of individuals in a few steps. Rather, it took hundreds of steps of people forwarding the e-mail on to reach the 20,000 who signed the found copies. As the researchers explain, this pattern suggests that the mechanics of a single piece of information spreading on a global scale is more complex than originally thought. Some of their results, which appear in a recent issue of the Proceedings of the National Academy of Sciences, reveal that people who forwarded the letter generally forwarded it to large numbers of other individuals. By contrast, most senders (94%) produced just one “daughter” that signed the letter. In other words, it seemed that most people ignored the e-mail. Citation: Chain letters reveal surprising circulation patterns (2008, April 10) retrieved 18 August 2019 from https://phys.org/news/2008-04-chain-letters-reveal-circulation-patterns.html A chain letter hoax that fooled thousands of people may help computer scientists understand how information spreads on a global scale. The final result was a “tree” of nodes and connections that was long and thin, not one that funneled out as in the case of rapidly spreading information. Gossip in smaller communities may fan out quickly, but – as the new study shows – such a pattern changes with scale. This large-scale spreading of information is a rare case, since most circulated e-mail messages never reach such a large number of recipients.“A natural assumption going into this study was that information would spread explosively, reaching many people in only a few steps,” said Liben-Nowell and Kleinberg. “Instead, a much more complex picture emerges, with the chain letter following longer, narrower paths. After this initial surprise, we eventually found possible ways to reconcile the deep, narrow structures we observed with the facts we knew about human social networks.”A couple things that might explain the pattern include individuals “forwarding” the petition to the same group of e-mail addresses copied on the e-mail they received (“replying to all”). Individuals who received the petition more than once typically only signed one of them, leaving others as dead ends. Also, individuals in the same network might have tried to all sign the same petition, and keep forwarding it to each other rather then adding their names to different lists – which produces the observed “single daughter” characteristic.Understanding how a single piece of information spreads on a large scale may have applications in a variety of areas, such as word-of-mouth marketing and investigating the spreading of technological innovations, news, and opinions. Contrary to spreading explosively, information traveling on large scales seems to be quite fragile, with many opportunities for getting lost. The pattern might hold true for different kinds of information spreading, as well.“We expect this kind of pattern would show up in certain other settings, but it’s an open question how general it is,” the researchers said. “For example, the other large-scale chain-letter for which we have data – a petition to support funding of National Public Radio – exhibits a spreading pattern that looks very similar. It’s natural to believe that jokes and news clippings on the Internet may well spread in similar ways, though there certainly could be differences in spreading patterns between information that is politically charged and information that is free of controversy.“Once we look more generally – say, at the spread of new technologies or new products by word-of-mouth, or the rise in name recognition of new celebrities or new political figures – it’s a fascinating open question to consider how diverse the different spreading patterns might be. But we expect that in all these cases, the spreading will likely have a structure that is more complex than simple models have suggested.” More information: Liben-Nowell, David, and Kleinberg, Jon. “Tracing information flow on a global scale using Internet chain-letter data.” Proceedings of the National Academy of Sciences, March 25, 2008, vol. 105, no. 12. 4633-4638.Copyright 2008 PhysOrg.com. All rights reserved. This material may not be published, broadcast, rewritten or redistributed in whole or part without the express written permission of PhysOrg.com. Medical researchers seek eradication of peste des petits ruminants diseaselast_img read more

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HP Labs find memristors can compute w Video

first_img(PhysOrg.com) — Researchers at HP Labs, the central research arm of HP, have discovered that a resistor with memory, a “memristor” can also perform logic operations. This means chips storing data may also be able to carry out computations without the need for a central processing unit (CPU). The discovery could mean computers will be able to become more compact and efficient than imagined previously. HP Labs first demonstrated the memristor in 2008 (see the PhysOrg article), but its theoretical existence was postulated in 1971 by Professor Leon Chua of the University of California at Berkeley. He named them memristors since they combine the electrical properties of a memory element and a resistor. They are able to retain a memory of the amount of charge that flowed through them after the power is turned off, and the resistance depends on the voltage history. According to HP Labs these tiny devices are the fourth basic building blocks of electronics, the others being resistors, capacitors and inductors. Explore further * Nature paper: www.nature.com/nature/journal/ … ull/nature08940.html* Memristor FAQ An image of a circuit with 17 memristors captured by an atomic force microscope. Each memristor is composed of two layers of titanium dioxide connected by wire. As electrical current is applied to one layer, the small signal resistance of the other layer is changed, which may in turn be used as a method to register data. © 2010 PhysOrg.com Self-Programming Hybrid Memristor/Transistor Circuit Could Continue Moore’s Law Now a team of researchers from the HP Information and Quantum Systems Laboratory at Palo Alto, California, have created architectures for memory chips using memristors, including one in which a stack of memristors are layered in a single chip. The team, led by the director of the laboratory, R. Stanley Williams, believe devices using the element could be developed for commercial use within a few years. These could allow supercomputers to work dramatically faster than today, and because memristors retain their memory, computers based on them could be turned off and on like a light switch. In a news release HP Labs said memristors are faster than current storage devices such as flash memory, and they use less energy and can store more than double the data. They could also be used in handheld devices with ten times more embedded memory than today’s devices. HP Lab predicts memristor-based processors could eventually replace silicon in uses such as e-reader display screens.Memristors are also unaffected by radiation, which can affect transistor-based technologies, and this means they could enable the development of smaller and more powerful devices, since the use of transistors is limited by Moore’s Law, which says the number of transistors that can be packed into a chip for a fixed cost has doubled every two years. Transistors on the most advanced chips have feature sizes as low as 22 nanometers, but there is a limit to how small they can become.Williams said that as “our brains are made of memristors,” the discovery could lead to computers that work more like human brains.The paper was published in Nature last week. Citation: HP Labs find memristors can compute (w/ Video) (2010, April 9) retrieved 18 August 2019 from https://phys.org/news/2010-04-hp-labs-memristors-video.html More information: 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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Jupiter has lost one of its cloud stripes

first_img Explore further (PhysOrg.com) — New photographs of the gas giant Jupiter, the first taken on May 9, show the massive reddish band of clouds known as the Southern Equatorial Belt in the planet’s southern hemisphere has disappeared from view. The South Equatorial Belt (SEB) has faded away leaving just the north belt (NEB) viewable in small telescopes. Image credit: Anthony Wesley 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: Jupiter has lost one of its cloud stripes (2010, May 14) retrieved 18 August 2019 from https://phys.org/news/2010-05-jupiter-lost-cloud-stripes.html © 2010 PhysOrg.com Aus amateur tells of ‘one in a million’ Jupiter spot The first photographs were taken by a noted Australian amateur astronomer, Anthony Wesley from Murrumbateman in New South Wales, using a 14.5 inch telescope. Wesley said he had been eagerly waiting to take photographs after Jupiter disappeared behind the sun and out of view for three months. In mid 2009 it was clear to Jupiter watchers the cloud band, which encircles the planet, was beginning to enter a new fading cycle. Wesley, an enthusiastic Jupiter observer, said the exact time the cloud belt will revive is unknown, but it fades every three to 15 years. Previous fading cycles have been characterized by violent and dramatic storms in the southern equatorial latitudes. The Northern and Southern Equatorial belts are composed of ammonia ice with phosphorus and some sulfur.It is not known why the belt periodically disappears, but it may be that it sinks lower if it cools, and then the view of it is obscured by clouds pouring in over the top of it. The clouds on Jupiter are tens of thousands of kilometers deep. Wesley said the phenomenon could be linked to storm activity that preceded the change.Wesley said Jupiter, the largest planet in the solar system, is fascinating to observe and photograph because the internal heat deep within the atmosphere makes it so dynamic and dramatic, and it can look different even from one day to the next. Watch Jupiter rotate and its cloud belts move with the winds. The time-lapse video was made using images shot during Voyager 1’s flyby of the planet in 1979. The most dramatic feature on Jupiter is the Great Red Spot, which now stands out more than usual since it is on the edge of the Southern Equatorial Belt, which has now faded from view. The Great Red Spot is a huge storm twice the size of Earth that has raged for at least three centuries, although astronomers said last year it appears to be shrinking. The photographs taken by Wesley have been released by The Planetary Society in California, and are also available on Wesley’s own website. In July last year Wesley was first to notice a dark blemish on Jupiter, probably caused by a comet. It is possible to see the features of Jupiter even with quite a modest telescope.last_img read more

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How to make ethical robots

first_img Copyright 2012 PhysOrg.com. All rights reserved. This material may not be published, broadcast, rewritten or redistributed in whole or part without the express written permission of PhysOrg.com. (PhysOrg.com) — In the future according to robotics researchers, robots will likely fight our wars, care for our elderly, babysit our children, and serve and entertain us in a wide variety of situations. But as robotic development continues to grow, one subfield of robotics research is lagging behind other areas: roboethics, or ensuring that robot behavior adheres to certain moral standards. In a new paper that provides a broad overview of ethical behavior in robots, researchers emphasize the importance of being proactive rather than reactive in this area. Citation: How to make ethical robots (2012, March 12) retrieved 18 August 2019 from https://phys.org/news/2012-03-ethical-robots.html The authors, Ronald Craig Arkin, Regents’ Professor and Director of the Mobile Robot Laboratory at the Georgia Institute of Technology in Atlanta, Georgia, along with researchers Patrick Ulam and Alan R. Wagner, have published their overview of moral decision making in autonomous systems in a recent issue of the Proceedings of the IEEE.“Probably at the highest level, the most important message is that people need to start to think and talk about these issues, and some are more pressing than others,” Arkin told PhysOrg.com. “More folks are becoming aware, and the very young machine and robot ethics communities are beginning to grow. They are still in their infancy though, but a new generation of researchers should help provide additional momentum. Hopefully articles such as the one we wrote will help focus attention on that.”The big question, according to the researchers, is how we can ensure that future robotic technology preserves our humanity and our societies’ values. They explain that, while there is no simple answer, a few techniques could be useful for enforcing ethical behavior in robots.One method involves an “ethical governor,” a name inspired by the mechanical governor for the steam engine, which ensured that the powerful engines behaved safely and within predefined bounds of performance. Similarly, an ethical governor would ensure that robot behavior would stay within predefined ethical bounds. For example, for autonomous military robots, these bounds would include principles derived from the Geneva Conventions and other rules of engagement that humans use. Civilian robots would have different sets of bounds specific to their purposes.Since it’s not enough just to know what’s forbidden, the researchers say that autonomous robots must also need emotions to motivate behavior modification. One of the most important emotions for robots to have would be guilt, which a robot would “feel” or produce whenever it violates its ethical constraints imposed by the governor, or when criticized by a human. Philosophers and psychologists consider guilt as a critical motivator of moral behavior, as it leads to behavior modifications based on the consequences of previous actions. The researchers here propose that, when a robot’s guilt value exceeds specified thresholds, the robot’s abilities may be temporarily restricted (for example, military robots might not have access to certain weapons). Explore further Though it may seem surprising at first, the researchers suggest that robots should also have the ability to deceive people – for appropriate reasons and in appropriate ways – in order to be truly ethical. They note that, in the animal world, deception indicates social intelligence and can have benefits under the right circumstances. For instance, search-and-rescue robots may need to deceive in order to calm or gain cooperation from a panicking victim. Robots that care for Alzheimer’s patients may need to deceive in order to administer treatment. In such situations, the use of deception is morally warranted, although teaching robots to act deceitfully and appropriately will be challenging.The final point that the researchers touch on in their overview is ensuring that robots – especially those that care for children and the elderly – respect human dignity, including human autonomy, privacy, identity, and other basic human rights. The researchers note that this issue has been largely overlooked in previous research on robot ethics, which mostly focuses on physical safety. Ensuring that robots respect human dignity will likely require interdisciplinary input.The researchers predict that enforcing ethical behavior in robots will face challenges in many different areas.“In some cases it’s perception, such as discrimination of combatant or non-combatant in the battlespace,” Arkin said. “In other cases, ethical reasoning will require a deeper understanding of human moral reasoning processes, and the difficulty in many domains of defining just what ethical behavior is. There are also cross-cultural differences which need to be accounted for.”An unexpected benefit from developing an ethical advisor for robots is that the advising might assist humans when facing ethically challenging decisions, as well. Computerized ethical advising already exists for law and bioethics, and similar computational machinery might also enhance ethical behavior in human-human relationships.“Perhaps if robots could act as role models in situations where humans have difficulty acting in accord with moral standards, this could positively reinforce ethical behavior in people, but that’s an unproven hypothesis,” Arkin said.center_img Researchers give robots the capability for deceptive behavior RI-MAN, a robot developed by researchers at RIKEN in Japan, was designed for human care. Image credit: RIKEN, Bio-Mimetic Control Research Center More information: Ronald Craig Arkin, et al. “Moral Decision Making in Autonomous Systems: Enforcement, Moral Emotions, Dignity, Trust, and Deception.” Proceedings of the IEEE. Vol. 100, No. 3, March 2012. DOI: 10.1109/JPROC2011.2173265 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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Physicist creates ice cream that changes colors as its licked

first_imgCredit: Cocinatis Spanish physicist, engineer, professor and ice cream lover Manuel Linares has together with a couple of colleagues created an ice cream that changes colors when it’s licked—in a cone. Not content with the life of a physics professor, Linares signed up for training with Asociación Empresarial Nacional de Elaboradores Artesanos y Comerciantes de Helados y Horchatas—a craftsmen and businessmen association in Spain that offers mentored coursework. Uber brings back on-demand ice cream trucks Explore further © 2014 Phys.orgcenter_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. Citation: Physicist creates ice cream that changes colors as it’s licked (2014, July 30) retrieved 18 August 2019 from https://phys.org/news/2014-07-physicist-ice-cream.html Linares pursued what he has described as a “Masters Diploma in Creating Artisan Ice Cream.” Intrigued by the ice that changes color under fluorescent lights, created by Charlie Francis, Linares set his sights on figuring out a way to create a type of ice cream that would change color in response to temperature changes and acids found in the human mouth. He enlisted the assistance of a couple of unnamed buddies and they all got to work in a lab that Linares put together with his own funds. Linares has told the press that it took the three of them just one week to come up with the color changing ice cream. The final product, which reportedly has a similar taste to tutti-frutti, has been named Xamaleón. The color changing comes about, some suspect due to the types of fruit that are used—plus a secondary ingredient, a spritz called the “love elixir” that gets sprayed onto the ice cream after its been scooped into a cone, which Linares has hinted, accelerates the color changing process. It starts out as periwinkle blue, then changes to pink and eventually becomes purple, as it’s licked.The ice cream is made of all natural materials, Linares has revealed, but other than listing some of the normal ingredients found in regular ice cream, he’s kept mum. That’s because he has big plans for the ice cream. He’s already opened a shop in Blanes, his hometown, with the goal of creating many more types of exotic ice cream, such as a variety that mimics the ice created by Francis, and another he’s already named Xamán—it will be made with Peruvian and African medicinal plants which will supposedly provide an aphrodisiac effect.last_img read more

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Study shows differences in brain activity of humans and macaques engaged in

first_img Pictured are the increases (orange-yellow) and decreases (blue) of neural activity in the brains of humans and macaques while performing the same attention task as measured by functional magnetic resonance imaging. In this study, the researchers found that the attention networks in humans fundamentally differ from those of macaques in three ways: the networks contain more areas, more information is shared between brain hemispheres, and humans possess an entire attention control network that is missing from macaques. The results suggest that the attention network has evolved to support uniquely human cognitive functions. Credit: Image courtesy of Gaurav Patel/New York State Psychiatric Institute/Columbia University Medical Center 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 National Academy of Sciences Barbary macaques. Credit: Wikipedia/Flickr/Karyn Sig At least two regions of the brain decide what we perceive As part of the experiment, one assumption has been that the macaque brain is likely very similar to the brain early humans had when the last common ancestors of the two species branched off in different directions. This means that the team was free to suggest that the differences they saw in the brain scans, likely indicate evolutionary changes that have occurred to our brains over the past 25 million years. Explore furthercenter_img © 2015 Phys.org In trying to better understand how it is the human brain works, scientists sometimes use macaques as stand-ins—that is because sometimes the experiments conducted cannot be performed on humans. One problem with this approach is that it is still not clear just how alike the brains of humans and macaques actually are. To learn more, the group conducted experiments that looked into which parts of the brain are active in both species engaged in the same task.The experiments consisted of putting eight human beings and two macaques in an fMRI machine while they engaged in the same task and watching which parts of the brain lit up. The task consisted of staring at a single point on a computer screen while objects were displayed near the single point and pressing a button when a certain image appeared. All the volunteers were trained on the task prior to being put into the fMRI machine.In analyzing the results the researchers discovered that the temporoparietal junction was much more active in the humans—they also noted that some other areas of the brain were more active as well. Furthermore, they discovered that there was more communication going on between the two brain hemispheres. In looking at all the differences taken together, the researchers conclude that humans have a more advanced attention control network, which they note, makes sense, because we humans need to filter information more than macaques—the monkeys, presumably, must be able to react to dangerous situations much more quickly than us. (Phys.org)—A group of researchers with affiliations to several institutions in the U.S. has identified some of the ways the human brain differs in the way it focuses on a task as compared to macaques. In their paper published in Proceedings of the National Academy of Sciences, the researchers detail experiments they carried out with both humans and macaques using fMRI scans. Citation: Study shows differences in brain activity of humans and macaques engaged in the same task (2015, July 14) retrieved 18 August 2019 from https://phys.org/news/2015-07-differences-brain-humans-macaques-engaged.html More information: Functional evolution of new and expanded attention networks in humans, Gaurav H. Patel, Proceedings of the National Academy of Sciences, DOI: 10.1073/pnas.1420395112AbstractMacaques are often used as a model system for invasive investigations of the neural substrates of cognition. However, 25 million years of evolution separate humans and macaques from their last common ancestor, and this has likely substantially impacted the function of the cortical networks underlying cognitive processes, such as attention. We examined the homology of frontoparietal networks underlying attention by comparing functional MRI data from macaques and humans performing the same visual search task. Although there are broad similarities, we found fundamental differences between the species. First, humans have more dorsal attention network areas than macaques, indicating that in the course of evolution the human attention system has expanded compared with macaques. Second, potentially homologous areas in the dorsal attention network have markedly different biases toward representing the contralateral hemifield, indicating that the underlying neural architecture of these areas may differ in the most basic of properties, such as receptive field distribution. Third, despite clear evidence of the temporoparietal junction node of the ventral attention network in humans as elicited by this visual search task, we did not find functional evidence of a temporoparietal junction in macaques. None of these differences were the result of differences in training, experimental power, or anatomical variability between the two species. The results of this study indicate that macaque data should be applied to human models of cognition cautiously, and demonstrate how evolution may shape cortical networks.last_img read more

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The hidden evolutionary relationship between pigs and primates revealed by genomewide study

first_img Explore further The researchers were able to identify additional PRE-1 elements using a ‘BLAST’ search of similar sequences. They also were able to predict the secondary assembled structure of PRE-1 RNA using RNAstructure Webservers ( rna.urmc.rochester.edu/RNAstru … edict1/Predict1.html ). The upshot of all this work, in the author’s own words, is that the ‘genomic performance of PRE-1 in terms of 7SL RNA-derived SINEs seemed convincing enough to classify the suidae into a family mainly inhabited by primates’.It has not escaped our attention that many readers of physorg who may have availed themselves of our previous coverage of the human hybrid origins theory, and a later follow up report, might come to premature conclusions here. With that in mind, I talked the creator of the hybrid origins theory, Eugene McCarthy, to get his take on this new research. He had this to say:”People have been congratulating me on this SINE study as if it somehow proved the hybrid theory of human origins. That’s nice of them, but it’s just one run in a nine-inning game. True, it does show that pigs are more closely related to primates than has generally been thought, which in turn suggests that a hybrid cross between pig and chimpanzee is more feasible than many have supposed. But to establish whether we’re actually descendants of an ancient cross between pig and chimpanzee, will require a detailed search of the human genome, not just a study of SINEs. I’ve explained the relevant issues in a recent rebuttal of some of the most common criticisms of the hybrid theory. It’s not as simple as some people like to think.” © 2015 Phys.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. More information: biorxiv.org/content/biorxiv/ea … 8/31/025791.full.pdf Who and exactly what were these generously-named beasts you might be asking yourself? The Laurasiatheria are the placental mammals believed to have hailed from the northern supercontinent of Laurasia after it split from Gondwana when Pangaea broke up. Their sister group, the Euarchontoglires, are the Supraprimates. These consensus classifications were made using the larger family of retrotransposons of which SINEs, and longer related LINEs, are themselves members of.In the pig genetics business, the preferred classification term for the family is ‘suidae’. Suidae PRE elements have been known since their original discovery back in 1987. The researchers identified the PRE1 element as a polymorphic insertion in the 5′-flanking region (about 686~985 bp upstream from the transcription initiator ATG codon) of the insulin growth factor binding protein (IGFBP7). Postulating that this 300 base pair insert sequence might be related to Alu inserts, they compared it with representative primate Alu sequences selected from the AF-1 database (software.iiar.res.in/af1/index.html). Incidentally, we should note that pig geneticists don’t have a monopoly on the term PRF-1. In related areas of pursuit, like drosophila genetics for example, a search for ‘PRE-1’ might be just as likely to return ‘photoreceptor regulatory element 1’. (Phys.org)—In the past, geneticists focused primarily on the evolution of genes in order to trace the relationships between species. More recently, genetic elements called SINEs (short interspersed elements) have emerged as a much better way to trace mammalian phylogeny, at least in the time since its massive radiation some 60 million years ago. That’s because the prolific SINE family evolved differently in every lineage to become widespread throughout the entire genome of each. But SINEs are more than just highly mobile markers, they have specific functions—functions which researchers are now decoding to understand not just how, but why they move about like they do.center_img Credit: overlay by Eugene McCarthy Secondary structure of ALU RNAs. Credit: rna.berkeley.edu/translation.html In humans, the most familiar and abundant SINE is the Alu transposable element. Originally derived from a small cytoplasmic signal recognition conglomerate known as the 7SL RNA, Alu inserts have since propagated themselves to generate an extended family over a million strong representing 11% of our entire genome. With the exception of the Alu inserts in the primate superfamily (and one seemingly anomalous occurrence of the ‘B1’ SINE the rat) all other SINEs were believed to have been derived from tRNAs rather than the 7SL RNA.A recent paper published in the bioRxiv now suggests that another species—the pig—has a unique family of SINEs whose evolution has closely paralleled ours. This collaboration between researchers from China, and Firefly Bioworks Inc. here in the US, reports that the swine SINE known as PRE-1 (for porcine repeat element), also likely derives from 7SL RNA. This work potentially pushes back the divergence time of 7SL RNA products to 80-100 million years ago—a re-adjustment that would presumably ground the 7SL RNA diversification or hybridization events to a place before the so-called boreoeutherians diversified into Laurasiatheria and Euarchontoglires. Citation: The hidden evolutionary relationship between pigs and primates revealed by genome-wide study of transposable elements (2015, September 23) retrieved 18 August 2019 from https://phys.org/news/2015-09-hidden-evolutionary-relationship-pigs-primates.html Orangutans harbor ancient primate Alulast_img read more

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Sediment study of African lake may help explain huge number of related

first_img © 2015 Phys.org 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. Drilling site in nearly 2000’ of water on Lake Malawi. Drill cores at this location penetrated more than 1250’ below the bottom of the lake. Credit: Jason Agnich, University of Minnesota Duluth. Journal information: Proceedings of the National Academy of Sciences (Phys.org)—A team of researchers affiliated with several universities in the U.S. has conducted a drilling study of Lake Malawi in South-East Africa and suggest their findings may help explain the large number of cichlid species that call the lake their home. In their paper published in Proceedings of the National Academy of Sciences, the team describes their drilling expedition, what the sediment samples showed and why they believe their findings may help explain the unusual number of related fish species.center_img Study shows evolution does not always mean more diversification Citation: Sediment study of African lake may help explain huge number of related fish species (2015, December 8) retrieved 18 August 2019 from https://phys.org/news/2015-12-sediment-african-lake-huge-fish.html More information: Continuous 1.3-million-year record of East African hydroclimate, and implications for patterns of evolution and biodiversity, Robert P. Lyons, DOI: 10.1073/pnas.1512864112AbstractThe transport of moisture in the tropics is a critical process for the global energy budget and on geologic timescales, has markedly influenced continental landscapes, migratory pathways, and biological evolution. Here we present a continuous, first-of-its-kind 1.3-My record of continental hydroclimate and lake-level variability derived from drill core data from Lake Malawi, East Africa (9–15° S). Over the Quaternary, we observe dramatic shifts in effective moisture, resulting in large-scale changes in one of the world’s largest lakes and most diverse freshwater ecosystems. Results show evidence for 24 lake level drops of more than 200 m during the Late Quaternary, including 15 lowstands when water levels were more than 400 m lower than modern. A dramatic shift is observed at the Mid-Pleistocene Transition (MPT), consistent with far-field climate forcing, which separates vastly different hydroclimate regimes before and after ∼800,000 years ago. Before 800 ka, lake levels were lower, indicating a climate drier than today, and water levels changed frequently. Following the MPT high-amplitude lake level variations dominate the record. From 800 to 100 ka, a deep, often overfilled lake occupied the basin, indicating a wetter climate, but these highstands were interrupted by prolonged intervals of extreme drought. Periods of high lake level are observed during times of high eccentricity. The extreme hydroclimate variability exerted a profound influence on the Lake Malawi endemic cichlid fish species flock; the geographically extensive habitat reconfiguration provided novel ecological opportunities, enabling new populations to differentiate rapidly to distinct species. Scientists have debated amongst themselves the possible reasons for such a large number of cichlid species in one lake—over a 1000, which is more than any other lake. Possible ideas have included unknown environmental factors or biological tendencies of the cichlid in general. In this new effort, the researchers suggest it might have been because lake levels changed so dramatically over the years.To learn more, the researchers traveled to the lake and conducted drilling operations, collecting sediment samples that revealed lake level changes over the past 1.3 million years. In looking at the data, the team found that that there were approximately 24 dry periods where the lake level dropped at least 650 feet and multiple periods where excessive moisture caused the lake to overflow into the surrounding area. There was also a big change that occurred approximately 800,000 years ago where the climate shifted from one that was mostly dry, to one that was much wetter. They noted that during some of the low level periods the lake likely broke into several pieces.The researchers suggest that such dramatic fluctuations in lake levels could account for the huge number of cichlid species, a dominant fish that would have had to be able to change quickly to adapt to new conditions—lower lake levels, for example, would have meant the water would have been a lot saltier with dramatically different pH levels, and if the lake broke up for long periods of time it would have led to isolation of some species.If the theory by the team is correct, it still does not explain, as they acknowledge, how it was that so many of the species that developed managed to survive till today. That answer will likely take a genetic study.last_img read more

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A novel way to put flame retardant in a lithium ion battery

first_img Schematic illustration for the fabrication of the microfibers by electrospinning. Credit: Liu et al. Sci. Adv. 2017;3:e1601978 More information: Kai Liu et al. Electrospun core-shell microfiber separator with thermal-triggered flame-retardant properties for lithium-ion batteries, Science Advances (2017). DOI: 10.1126/sciadv.1601978AbstractAlthough the energy densities of batteries continue to increase, safety problems (for example, fires and explosions) associated with the use of highly flammable liquid organic electrolytes remain a big issue, significantly hindering further practical applications of the next generation of high-energy batteries. We have fabricated a novel “smart” nonwoven electrospun separator with thermal-triggered flame-retardant properties for lithium-ion batteries. The encapsulation of a flame retardant inside a protective polymer shell has prevented direct dissolution of the retardant agent into the electrolyte, which would otherwise have negative effects on battery performance. During thermal runaway of the lithium-ion battery, the protective polymer shell would melt, triggered by the increased temperature, and the flame retardant would be released, thus effectively suppressing the combustion of the highly flammable electrolytes. Safer, more environmentally friendly flame retardant with first-of-its-kind dual effects SEM image of the TPP@PVDF-HFP microfibers. Scale bar, 5 μm. Credit: Liu et al. Sci. Adv. 2017;3:e1601978 Schematic of the “smart” electrospun separator with thermal-triggered flame-retardant properties for lithium-ion batteries. Credit: Liu et al. Sci. Adv. 2017;3:e1601978 Reports of phones and hoverboards catching fire due to short circuits in batteries have caused alarm in the personal electronics industry—both by users and those that make the devices. Unfortunately, up until now, engineers have not been able to solve the problem completely. Most such efforts involve re-engineering devices to prevent short-circuiting and thus overheating, or attempting to put flame retardant directly in the batteries. Neither approach has proven to be entirely satisfactory. Re-engineering does not always solve the problem and the addition of flame retardant greatly reduces battery efficiency. In this new effort, the researchers describe an approach that thus far appears to offer some help—it does not stop overheating from occurring, but it is able to prevent fire.The new approach involves encapsulating a common flame retardant called triphenyl phosphate in an extremely tiny sheath made of plastic fibers and then inserting several of them into the electrolyte that sits between the anode and cathode. The sheath keeps the retardant from actually coming into contact with the electrolyte material, which is flammable and the source of most battery fires. But the plastic fibers in the sheath have a melting point of 160° Celsius—if that temperature is reached, the plastic melts and the retardant is released into the electrolyte quashing a potential fire. Journal information: Science Advances In test devices using their encapsulated flame retardant, the researchers report that the sheaths melted and the retardant was released and merged with the electrolyte in just 0.4 seconds and because of that fires were averted.In practice, it is presumed that such an occurrence in a device would initiate a hardware error before the battery stopped working to alert a user to what had occurred. Thereafter, a user would also presumably have to purchase a new battery in order to continue using their device which would survive the overheating event. GIF animation showing the EC/DEC electrolyte is highly flammable. Credit: Liu et al. Sci. Adv. 2017;3:e1601978 Schematic illustration for the fabrication of the microfibers by electrospinning. Credit: Liu et al. Sci. Adv. 2017;3:e1601978center_img GIF animation showing the EC/DEC electrolyte is highly flammable. Credit: Liu et al. Sci. Adv. 2017;3:e1601978 Explore further © 2017 Phys.org GIF animation showing the flammability of the EC/DEC electrolytes in the presence of the TPP@PVDF-HFP separator. The flames of the electrolyte diminish rapidly and are completely extinguished within 0.4 seconds. Credit: Liu et al. Sci. Adv. 2017;3:e1601978 (Phys.org)—A team of researchers at Stanford University has found a novel way to introduce flame retardant into a lithium ion battery to prevent fires from occurring. In their paper published in the journal Science Advances, the team describes their technique and their results when testing it. GIF animation showing the combustion of EC/DEC electrolyte with the flame-retardant TPP. Credit: Liu et al. Sci. Adv. 2017;3:e1601978 Citation: A novel way to put flame retardant in a lithium ion battery (2017, January 16) retrieved 18 August 2019 from https://phys.org/news/2017-01-flame-retardant-lithium-ion-battery.html This document is subject to copyright. 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Fantasy called India

To celebrate their 25th anniversary year, Abu Jani and Sandeep Khosla have come out with India Fantastique, published by Thames & Hudson, in two volumes – Fashion [Volume I] and Interiors [Volume II].Known both for their fashion creations for men and women and for interior design, their reputation extends far beyond India: many international celebrities wear Jani-Khosla creations, among them Dames Judi Dench and Maggie Smith, Sophie Marceau and Sarah Brown. Also Read – ‘Playing Jojo was emotionally exhausting’The first volume of India Fantastique displays dozens of the duo’s impossibly elegant designs created over the past 25 years, including close-ups of exquisitely crafted details. The second volume focuses on their extensive work in interior design. Their hallmark maximalism runs riot in privately commissioned interiors, which incorporate art, artifacts, antiques and vintage textiles. An exhibition of the designers’ work was held at Sotheby’s London in September to coincide with the launch of India Fantastique. read more

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