Can vapes save the world from smoking? When a weak intensity and high intensity beam are aimed at a liquid crystal valve, the output pulse is split into different diffracted pulses, each showing a different group velocity. The images at left demonstrate image delay: image (a) is an original image imposed on the input pulse, and image (b) is the image from an output pulse delayed by several milliseconds. Credit: S. Residori, et al. Explore further In a vacuum, the speed of a light pulse is always a constant at 186,000 miles (300,000 km) per second. But by changing the medium through which light travels, physicists can slow down light pulses, and possibly create highly sensitive light interferometers, among other devices. Over the past decade, researchers have demonstrated several methods that can slow light, such as using ultracold atoms, silicon waveguides, or the quantum coherence effect. But now, for the first time, researchers have shown that liquid crystals can also slow light, and can provide group velocities of less than 0.2 millimeters per second – the slowest so far achieved. The study, performed by physicists Stefania Residori and Umberto Bortolozzo of the Institut Non Lineaire de Nice, and Jean-Pierre Huignard of Thales Research and Technology, both in France, appears in a recent issue of Physical Review Letters.The key to liquid crystals’ ability to slow light is the large dispersion properties associated with two-photon wave mixing. When the researchers aimed two beams – one with weak intensity and one with higher intensity – at a liquid crystal valve, the liquid crystal acted like a hologram and split the beam into several beams that went off in different directions. Each of these diffracted beams had a different delay or no delay at all, depending on the direction of their path within the liquid crystal.“The main point is that slowing down optical pulses is equivalent to making the pulses travel inside a medium that has a very large refractive group index,” Residori explained to PhysOrg.com. “Thus, even though the light pulse travels over a small distance, its effective path becomes very large. Since the precision of an interferometer is given by the difference of the optical path between the two arms, then by inserting the slow light device on one arm, it will be possible to reach unprecedented sensitivity.”The researchers also used the technique to demonstrate image delay. They imposed a 1-cm2 image on the low-intensity beam for a pulse duration of 180 milliseconds, and illuminated the image with the high-intensity beam. The output beams showed that the image was delayed by 82 milliseconds as it traveled through the liquid crystal. The image, which had a spatial resolution of 15 micrometers, appeared without any significant distortion due to the crystal’s homogeneity. The ability to achieve both fast and slow light in a single device could have many optical uses. As the researchers explained, there is an optimum trade-off between amplifying the slow light pulses and reducing the intensity of the fast light pulses to achieve a good balance. In addition to optical communication networks, ultraslow group velocities could be useful for greatly increasing the sensitivity of light interferometers, testing fundamental laws of physics, and for precision metrology measurements. “Liquid crystal technology is very well developed and liquid crystal devices could be easily commercialized,” Residori explained as some advantages of the technique. “Moreover, the device is very compact and of small size (20x20x1 mm), and the experimental apparatus is relatively simple compared to other techniques.”More information: Residori, S.; Bortolozzo, U.; and Huignard, J. P. “Slow and Fast Light in Liquid Crystal Light Valves.” Physical Review Letters 100, 203603 (2008).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. Citation: Liquid Crystals Slow Light Pulses to a Snail’s Pace (2008, June 10) retrieved 18 August 2019 from https://phys.org/news/2008-06-liquid-crystals-pulses-snail-pace.html This document is subject to copyright. Apart from any fair dealing for the purpose of private study or research, no part may be reproduced without the written permission. The content is provided for information purposes only.
Citation: Scientists Extend the Lifetime of Quantum Memory (2009, January 2) retrieved 18 August 2019 from https://phys.org/news/2009-01-scientists-lifetime-quantum-memory.html (PhysOrg.com) — Storing and sending information using quantum phenomena is one of the hottest areas of research today; scientists across the globe are investigating how to make quantum communication possible for real-life applications. In a key step, a group of researchers was recently able to greatly improve the lifetime of a form of quantum memory. The electrons quickly decayed from the c level, but jumped down to a rather than back to b. This is due to energy loss from the light they emitted during the jump, know as Raman radiation.Finally a “read” laser was applied to the atom array, exciting the a-to-c transition. The electrons decayed from c to b, emitting a second, weaker round of Raman emission, known as the “idler” field. The idler field is detected and interpreted, allowing the researchers to “read off” the information that had been briefly stored.This approach differs from previous rubidium quantum-memory schemes. The longest memory time prior to this work was achieved using a free-moving, magnetically sensitive rubidium-atom ensemble; it had a lifetime of 32 microseconds. But the atoms were able to fall freely, which, in conjunction with small magnetic fields, resulted in a limited memory time.In this case, the atoms’ motion is greatly suppressed and the clock transition is not sensitive to magnetism. These features greatly improve the memory time.Quantum communication is based on the phenomenon of entanglement, the mysterious way in which two quantum entities, such as photons (light particles), can “know” each other’s quantum state despite never having been in contact. Parties in remote locations share and store the entangled state, thus transmitting a quantum bit across a distance.More information: Nature advance online publication, 7 December 2008 DOI: 10.1038/nphys1152Copyright 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. In this case the research group achieved a quantum memory lifetime of 6 ms, more than 100 times as long as the next-best reported time. The scientists—from the Georgia Institute of Technology, the University of Maryland, and Università degli Studi dell’Insubria (Unviersity of Insubria), in Italy—describe their work in the December 7 online edition of Nature Physics.“Though several technical hurdles still remain, this advance represents a significant step toward the realization of quantum networks and the distribution of entangled states over long distances,” said corresponding author Stewart Jenkins to PhysOrg.com. Jenkins is affiliated with both Georgia Tech and the University of Insubria.Quantum memory schemes are extremely sensitive to the surrounding environment, limiting how long they can store data. To transmit quantum information over a long distance, the storage times must be longer than scientists have been able to achieve thus far. Transmitting quantum information across 1,000 kilometers, for example, takes a minimum of 5 milliseconds (ms), meaning that a quantum-memory scheme must be viable for at least that long.This group’s work takes advantage of rubidium’s “clock transition,” the movement of electrons between two specific energy levels. This electron jump is what makes rubidium atoms appropriate for use in atomic clocks, in which the standard for keeping time is based on the precise (and unchanging) frequency of microwaves emitted when the electrons undergo the transition.The transition is the medium by which the atoms store quantum information. The process involves three key atomic energy levels, denoted a, b, and c, where a is the lowest and c is the highest. The energy difference between a and b is very small; they are “hyperfine” levels of the ground state, the lowest state of an atom.Jenkins and his colleagues trapped between 100,000 and one million super-chilled rubidium atoms within a lattice of laser beams, which separated and immobilized the atoms into a grid-like pattern. They then “set” the atoms to the proper excitation state using a “write” laser, imparting the atom’s electrons with enough energy to move from b up to c. The transition represents a value of one bit, the most basic unit of information, typically denoted as a “0” or “1.” (In conventional memory schemes, bits are often defined by capacitors, with a charged capacitor representing a “1” and an uncharged capacitor representing a “0.”) Creating two-dimensional layered Zintl phase by dimensional manipulation of the crystal structure 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.
More information: www.zenrobotics.com/english/company/media/ (PhysOrg.com) — The Finnish firm ZenRobotics has designed and built a robot that can sort through construction waste and pluck out recyclable material moving by on conveyer belt and then deposit it in an appropriate bin. The robot is currently able to correctly identify roughly half of the material it processes, which may not sound that impressive, until you consider that as things stand now, nearly 100% of such construction waste now winds up in landfills, un-recycled and polluting the planet. Citation: Finnish robotics firm develops trash recycling robot (2011, April 20) retrieved 18 August 2019 from https://phys.org/news/2011-04-finnish-robotics-firm-trash-recycling.html Robot Trash Collectors Are Roaming the Streets of Italy (w/ Video) 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. Using such a robot would not only help to recycle construction waste, which some believe accounts for up to half of all landfill material, but would be able to do so in an environment that oftentimes is hazardous to humans due to the wide mix of sometimes toxic materials that arise when buildings are being built or torn down. © 2010 PhysOrg.com This type of work is groundbreaking due to the fact that robots have been traditionally relegated to performing more easily definable tasks, such as repeatedly welding two pieces of metal together. To separate good trash from the bad, however, a robot must first be programmed to recognize very basic materials, and then to “learn” as it goes, by doing, i.e. it must have some degree of artificial intelligence. In the current setup, construction waste is deposited onto a conveyer belt where it is carried into a processing room where the robot resides. The robot reaches down and grabs stuff off the conveyer, analyzes it, and if it recognizes what it sees, drops it into a nearby bin marked for just that type of material. Anything not recognized stays on the belt and is deemed trash. Currently, the robot is able to identify certain types of plastics, metals, concrete and wood. The as yet unnamed robot is basically an arm with a gripper connected to a computer and uses various already proven technologies to perform its task, such as metal detection, weight measurement, 3-D scanning, tactile feedback and spectrometer analysis to measure light waves bounced back off of different materials. It’s easy to see how new measuring devices could be added as they become available, especially when you consider the massive amounts of money already invested by various space agencies for probes sent to space to do essentially the same thing as they investigate planets, comets, etc.
Citation: Turtle embryos move to bask in the sun (2011, May 25) retrieved 18 August 2019 from https://phys.org/news/2011-05-turtle-embryos-bask-sun.html More information: Behavioral thermoregulation by turtle embryos, PNAS, Published online before print May 23, 2011, doi: 10.1073/pnas.1102965108AbstractMobile ectothermic animals can control their body temperatures by selecting specific thermal conditions in the environment, but embryos—trapped within an immobile egg and lacking locomotor structures—have been assumed to lack that ability. Falsifying that assumption, our experimental studies show that even early stage turtle embryos move within the egg to exploit small-scale spatial thermal heterogeneity. Behavioral thermoregulation is not restricted to posthatching life and instead may be an important tactic in every life-history stage. Sea turtles make comeback on Texas coast 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. (PhysOrg.com) — Turtles, like the majority of reptiles, are unable to regulate their own body heat and use their environment to control their temperature. In order to stay warm, reptiles will bask in this sun. Researchers believed that this was a learned behavior, however, in a journal published in the Proceedings of the National Academy of Sciences, Wei-Guo Du from the Chinese Academy of Sciences have found that this basking behavior starts while the turtle is still in the egg. Turtle eggs. Image credit: naturescrusaders © 2010 PhysOrg.com Du collected 260 Chinese soft shelled turtle (Pelodiscus sinensis) eggs from local turtle farms and placed them in jars and warmed them with a heat lamp. The side of the egg where the heat lamp was placed created a temperature increase of one degree Celsius. With a combination of candling (the use of light through a shell to see the embryo) and a partial removal of shells, Du discovered that the embryos seemed to sense this and moved to the side of the egg closest to the heat. When the light was moved, the embryos would follow to the warmer side.In another, more natural experiment, Du used 540 eggs and buried them in natural nest settings like a sloping river bank or a flat field. When the eggs were placed into the nests, he arranged them so that the embryos were in the uppermost part of the egg. After about 20 days, the embryos which had been buried on the slop had moved to toward the bank while those in the flat field, which had the sun shining from directly overhead, had stayed in the same position.This ability to move and control their temperature can be a big difference for the young turtle. A change in temperature for the turtle embryo by only one degree Celsius can mean it will hatch 4.5 days sooner and reduce their risk of becoming a meal for egg predators. This ability to determine their path also raises an interesting question which Du plans to research. For many reptiles, the sex is determined by the temperature they were incubated in. Those in the 22.5 – 27 degree range are usually male while those at 30 degrees are usually female. The question is, are these turtle embryos then able to determine if they are going to be a boy or a girl? Explore further
Experimental cell and sketch of the twist excitation. The pictures show the initial (left) and final (right) states for a ensemble of 25 000 cubes submitted to N = 3×105 twists of intensity Γ=1.01. Credit: Physical Review Letters (2017). DOI: 10.1103/PhysRevLett.119.228002 Predicting a die throw (Phys.org)—A small team of researchers from Universidad de Navarrahas in Spain and Cinvestav Unidad Monterrey in Mexico has found that applying alternating twists to a cylinder full of square dice causes the dice to line up. In their paper published in the journal Physical Review Letters, the group describes their experiments with agitating dice and what they found. Most people have witnessed what happens when randomly agitating a jar full of rocks, nuts or other hard objects—over a short time, they line up in a way that causes them to become more compacted. Manufacturers have learned to take advantage of this by designing machines that agitate or tap containers to compress the materials. In this new effort, the researchers report that alternating agitation does an even better job, at least with small, square objects.In their experiments, the researchers loaded 25,000 plastic dice, each approximately a half-centimeter on a side, into a clear cylinder. They then applied different agitation effects to the cylinder to see which might cause the most effective compaction. They found that an alternating twisting, similar to that used by a common clothes washing machines worked best—but only when enough acceleration was applied. They found that the applied rotation exerted an outward force against the walls of the cylinder while the jolt that occurred when a spin motion was suddenly halted and then reversed caused the dice to shuffle slightly. Applying the alternating twisting technique caused the dice to line up top to bottom and also to form concentric circles when looked at from above. Play With the angular acceleration below the threshold, the twisting oscillation does not lead to complete ordering of the dice in the center, even after a day of agitation (100,000 twists), as shown in this time-lapse video. (A logarithmic time scale is used, with identical intervals of time passing between images for 100; 1000; 10,000; and 100,000 cycles.). Credit: K. Asencio et al., Phys. Rev. Lett. (2017) The researchers also found that for the technique to work, enough rotational acceleration had to be applied to sufficiently cause a useful amount of movement by the dice when it was suddenly halted. More specifically, they found that acceleration of approximately half that of gravity caused the dice to reach a maximum density after 10,000 alternating twists. Lower accelerations were not sufficient to cause the dice to line up in a reasonable amount of time.The researchers suggest their findings offer a possible new means of compacting materials as part of a manufacturing processes. PausePlay% buffered00:0000:00UnmuteMuteDisable captionsEnable captionsSettingsCaptionsDisabledQuality0SpeedNormalCaptionsGo back to previous menuQualityGo back to previous menuSpeedGo back to previous menu0.5×0.75×Normal1.25×1.5×1.75×2×Exit fullscreenEnter fullscreen More information: K. Asencio et al. Experimental Study of Ordering of Hard Cubes by Shearing, Physical Review Letters (2017). DOI: 10.1103/PhysRevLett.119.228002ABSTRACTWe experimentally analyze the compaction dynamics of an ensemble of cubic particles submitted to a novel type of excitation. Instead of the standard tapping procedure used in granular materials we apply alternative twists to the cylindrical container. Under this agitation, the development of shear forces among the different layers of cubes leads to particle alignment. As a result, the packing fraction grows monotonically with the number of twists. If the intensity of the excitations is sufficiently large, an ordered final state is reached where the volume fraction is the densest possible compatible with the boundary condition. This ordered final state resembles the tetratic or cubatic phases observed in colloids. Explore further Journal information: Physical Review Letters © 2017 Phys.org Citation: Applying alternating twists to cylindrical container found to cause dice to line up (2017, December 7) retrieved 18 August 2019 from https://phys.org/news/2017-12-alternating-cylindrical-dice-line.html This document is subject to copyright. Apart from any fair dealing for the purpose of private study or research, no part may be reproduced without the written permission. The content is provided for information purposes only.
Citation: Imagining the possibility of life in a universe without the weak force (2018, February 5) retrieved 18 August 2019 from https://phys.org/news/2018-02-possibility-life-universe-weak.html © 2018 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. Explore further More information: Universes without the Weak Force: Astrophysical Processes with Stable Neutrons, arXiv:1801.06081 [astro-ph.GA] arxiv.org/abs/1801.06081v1AbstractWe investigate a class of universes in which the weak interaction is not in operation. We consider how astrophysical processes are altered in the absence of weak forces, including Big Bang Nucleosynthesis (BBN), galaxy formation, molecular cloud assembly, star formation, and stellar evolution. Without weak interactions, neutrons no longer decay, and the universe emerges from its early epochs with a mixture of protons, neutrons, deuterium, and helium. The baryon-to-photon ratio must be smaller than the canonical value in our universe to allow free nucleons to survive the BBN epoch without being incorporated into heavier nuclei. At later times, the free neutrons readily combine with protons to make deuterium in sufficiently dense parts of the interstellar medium, and provide a power source before they are incorporated into stars. Almost all of the neutrons are incorporated into deuterium nuclei before stars are formed. As a result, stellar evolution proceeds primarily through strong interactions, with deuterium first burning into helium, and then helium fusing into carbon. Low-mass deuterium-burning stars can be long-lived, and higher mass stars can synthesize the heavier elements necessary for life. Although somewhat different from our own, such universes remain potentially habitable. A team of researchers at the University of Michigan has conducted a thought experiment regarding the nature of a universe that could support life without the weak force. In their paper uploaded to the ArXiv preprint server, the researchers suggest life could be possible in such an alternative universe, but it would definitely be different from what we observe in ours. MWA radio telescope expansion complete—Exploration of the universe’s first stars begins Credit: CC0 Public Domain Physicists have debated the possibility of the existence of alternate universes for some time, though there is no evidence they exist. In this new thought experiment, the team at UM wondered if one or more of the laws of physics that we have discovered in this universe might not exist in others—if they do exist. Because it would be hard to imagine a universe that could exist without gravity and the strong and electromagnetic forces, the team instead focused on the weak force—the one behind such things as neutrons decaying into protons.The team wondered what a universe without the weak force would look like. To visualize it, they created a simulation of such a universe starting from the Big Bang. In the simulation, matter was still created and condensed into stars, but from there on, things would be different, because in our universe, the weak force is responsible for the creation of the heavier elements. In a universe without the weak force, the existence of anything other than stars would require more free protons and fewer neutrons (because they could not decay). In such a universe, neutrons and protons could link up to make deuterium.Stars fueled by deuterium instead of hydrogen, the researchers note, would still shine, they would just look different—likely redder and larger. But such stars could also serve as the source of all of the elements in the periodic table prior to iron, and the stellar winds could carry them out into space. If planets happened to form, they further note, they could hold water made from deuterium rather than hydrogen—and it is not impossible to imagine, they suggest, life forms made with deuterium water. Journal information: arXiv
Amidst the din, a corner in Delhi is going to be lit up spiritually to take devotion to its zenith. The lilting tunes of Bhakti Sangeet have the power of transporting a being into another world. Are you ready to be one as the spiritually buoyant genre of music Bhakti Sangeet plays out live for a three day long programmme organised by Sahitya Kala Parishad and Department of art and culture. The festival will be inaugrated by the honorable chief minister of Delhi, Sheila Dixit. Also Read – ‘Playing Jojo was emotionally exhausting’From the uplifting vedic chants to the intensity of qawallis, the festival will feature all of it. It will paint your days with myriad cultural forms of devotion through bhajans, vedic chants, carnatic music, qawwalis and sufiana kalams. While Madan Gopal Singh and Jaipu Khan Langa bring you the sufi poetry of Punjab and the rich Bhakti music of Rajasthan, respectively,the pop sensation Daler Mehndi will done a new avatar with his renditions of Sufi music. It will bring together a number of artistes from across the country to delve you into a different world altogether.Bhakti and sufi saints have laid down the foundation of a composite culture; with these musical evenings, the challenge is to bring together devotional music of different genres. What better means could it have than music?DETAILWhen: April 19 to 21 Where: Nehru Park, Chanakya Puri
Who said there are no takers for poetry? The crowd that gathered in a city cafe on Thursday for a poetry reading session by Jeet Thayil from the book The Right Kind of Dog by Adil Jussawalla, reverses the theory. A set of subtle poems–sometimes funny, sometimes sad, but always thought-provoking, The Right Kind of Dog talks about the things that young people struggle with: rejection, learning to find their feet, trying to fit in and being forced to conform. Written in Adil Jussawalla’s terse and sharp style, with stunning and suggestive illustrations, the book is a must have. Adil Jussawalla is the author of three books of poems, the most recent being Trying to Say Goodbye (Almost Island Books, 2011).
What happens when different artists from around the world come together and display array of their works? It’s an art fair, full of creative energy and colours. If you want to see some crazy art unbounded to any particular genre or vision then a visit to, United Art Fair-2013 is a must.The second edition of UAF will continue its model of an artist-driven fair, to expand on the parameters of contemporary art by displaying a wider variety of disciplines, practitioners, media and materials. This year under the curation of well known artist Peter Negy, group and solo shows will take place. Also Read – ‘Playing Jojo was emotionally exhausting’While paintings, sculptures, photography and works-on-paper would constitute the majority of works at the fair, it will also include examples from all fields of design like, graphic art, fashion, textiles, furniture, and ceramics among others. One will also find works from the genres of folk and tribal art, crafts and ritual arts.The United Art Fair had its premiere in September 2012. It radically ventured away from the normal art fair model, choosing instead to showcase works of art which could be sourced from artists directly, without the intermediary of a gallery or a dealer, but could be available for sale to the public visiting the fair. Also Read – Leslie doing new comedy special with NetflixLooking at the commercialised art scenario, where the fresh talent do not have any support system, beauty of this fair lies in the fact that, each artist would contribute to the fair by giving their art work to the organisers for their participation, while the organisers themselves would be responsible for selling the multiple works on display directly to the collectors and paying the artists for their works which had been sold.The design of the fair has been in response to the works of art themselves, to create a diversity of spaces to encounter a diversity of art works. In fact, this diversity has been our foundation, with the curatorial team and collaborators brought in specifically to gain access to a wider range of materials to be exhibited. The works will all be installed in communication with each other, standing as individual works by individual artists, not sequestered into ghettos defined by neither mediums nor the curators who have chosen them for inclusion.The emphasis of the fair will be on younger, undiscovered talent new to the marketplace and outside of the existing gallery system, overlooked work of a few senior artists will also be exhibited. So, mark your calendars and do pay a visit to have a fresh breath of art!When: 14 to 17 September, 3:30pm onwardsWhere: Pragati Maidan
The Governor has just had a child and his wife is incredibly jealous of the attention that he gives to his son. The Governor’s brother, the Fat Prince, stages an insurrection on Easter Sunday. He kills the Governor and forces his wife to flee. In her haste, she leaves behind the child, who is found and taken care of by Grusha, a kitchen maid. Time passes as political upheaval continues. Azdak is appointed Judge and eventually he takes over the case of Grusha and the child. The Governor’s wife wants the child back while Grusha wants to keep the child, whom she has raised for the past two years and loves deeply. Matters come to a head as Azdak employs a unique strategy to resolve the situation. Also Read – ‘Playing Jojo was emotionally exhausting’The play by group Triveni, titled Gopal Ane Sayaji is a play written by Makarand Musale, to commemorate the 150th Birth Anniversary of the Maharaja Sayajirao III of the erstwhile Baroda state. Though a prince of a native state, he jealously guarded his rights and status even at the cost of annoying the British Indian Government. The play examines the crises in the life of Sayajirao, the ruler, and the conflict within him as a ruler and as a simple village man, Gopalrao. Both the central characters, Gopalrao and Sayajirao, travel through times of history, unfolding the crisis and drama with the British Raj and the social rigidity. Also Read – Leslie doing new comedy special with NetflixAnother play Blackboard Land explores the psyche of human violence. The plot revolves around 3 people who are caught in an isolated place at the periphery of war. The place is situated near the merging borders of two states, or rather regions, which may have a common ethnic background.The dialects spoken by the characters differ from each other, which further aggravates the conflict between them to a point when the mistrust starts bordering on physical violence. This adapted presentation is an attempt to reach the depths of the human psyche through the layers of culture, religion, ethnicity and language. A play based on Brecht’s Exception and the Rule, adapted and translated into the Hindi by Shrikant Kishore, Saudagar basically speaks metaphorically of how First World countries have hollowed out the pre-existing societies under the pretence of discovery and modernisation. The Saudagar in the play is the bigger man who gets away with all the wrong-doing. With a hired guide and coolie, he sets out in search of oil to become even richer. He is unable to digest the fact that the guide and the coolie are becoming friends, and finally ends up shooting and killing the coolie.Once a wrong is committed it must be covered up, and so the plot proceeds.When: Till 15 January