Producing light in the terahertz range gets tricky, though: “Currently, the way to generate this radiation at room temperature involves solid state lasers that are bulky and energy consuming.” In order to facilitate the creation of practical terahertz devices and systems, Belkin points out that “we want to create a compact electrically-pumped terahertz source, similar to semiconductor lasers in infrared and visible that you can fit in a laser pointer, and to be able to operate it at room temperature.” The applications for a laser device operating in the terahertz range include security screening, radio astronomy, biomedical imaging, and spectroscopy. “The main funding for our work comes from the security aspect,” Belkin explains. “Terahertz rays can penetrate through cardboard, plastic, clothing, and many other materials, so that we can image a concealed weapon, or detect chemical and biological agents through sealed packages.” Along with colleagues at Texas A&M University and the Swiss Federal Institute of Technology, Zürich, Belkin believes a first step has been made in developing a practical room-temperature electrically-pumped semiconductor laser device that produces terahertz radiation. The key is to combine, in one device, a dual-wavelength infrared semiconductor laser and giant optical nonlinearity for difference-frequency mixing. Their current device produces approximately 300nW of 5THz radiation at room temperature. The findings are published in the article “Room temperature terahertz quantum cascade laser source based on intracavity difference-frequency generation” in the May 19 issue of Applied Physics Letters.“We undertook an unusual approach to the problem, going around with a dual-wavelength quantum cascade laser operating at room-temperature in mid-infrared and utilizing a nonlinear optical process of difference-frequency generation inside the laser cavity to produce terahertz radiation,” explains Belkin, expounding via email. He continues: “In order to make the concept work, we needed to integrate giant optical nonlinearity inside the laser cavity. This has been done by growing a structure containing a stack of ultra-thin atomic layers of semiconductor materials on top of each other. This approach allowed us to adjust the energy levels in the structure to create an artificial medium with very large optical nonlinearity.”Right now, Belkin admits, the terahertz power output of their current devices is smaller that he and his colleagues would like. However, they have demonstrated the first room-temperature electrically-pumped semiconductor laser source of terahertz radiation. Additionally, the team is already making changes to the design to improve the terahertz power output. “We are confident that the power output of our devices can be improved several orders of magnitude when the structure is fully optimized,” Belkin says. Citation: Terahertz laser source at room temperature (2008, June 3) retrieved 18 August 2019 from https://phys.org/news/2008-06-terahertz-laser-source-room-temperature.html Engineers demonstrate first room-temperature semiconductor source of coherent Terahertz radiation Explore further “There is a growing interest in utilizing terahertz radiation, or T-rays, for a variety of applications,” Mikhail Belkin, a scientist at Harvard University, tells PhysOrg.com. “The terahertz region is a part of the electromagnetic spectrum that lies between the radio waves and infrared/visible light.” 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.
Month: August 2019
Journal information: Biology Letters 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. Mourning cuttlefish are not actually fish, they are more closely related to squid and octopus, and like them they can not only shoot ink into the water to make a hasty escape from predators, but can change the coloring of their skin at will. Up until now, researchers had assumed the coloring changes were used only to help the cuttlefish hide from predators passing by. After witnessing one specimen change his coloring on just one side of his body to mask his presence from a rival male while simultaneously displaying different coloring on the other, the team looked a little deeper, studying pictures and video of the cuttlefish taken over time of cuttlefish that lived in Sydney Harbor and discovered something that had been missed before; males displaying split-down-the-middle coloring when trying to mate with a female while at the same time, hiding that fact from other males in the area. This video shows tactical deception employed in the mesocosm. Rival males are to the right of screen. This research was published in the journal Biology Letters in the paper: It pays to cheat: tactical deception in a cephalopod social signalling system by Culum Brown, Martin P. Garwood and Jane E. Williamson. It doesn’t work every time of course as sometimes the rivals catch on, which generally results in a fight; something cuttlefish want to avoid because sometimes another rival can sneak in while two others are otherwise engaged and make the whole bout moot.The researchers say the deceptive ploy by the male cuttlefish is yet another instance of intelligence and that the males are smart enough to employ the technique only when it has a fair chance of working. Thus, if more than two males (or multiple females) are around, they don’t even bother. The fact that the behavior is so directed indicates the cuttlefish are aware of what they are doing, which shows that some sort of thinking is going on. Being cephalopods, cuttlefish are members of one the smartest groups of creatures that live under the sea, with bigger brains relative to body size than any other invertebrate. They’re also very social. Some have been seen to bond with schools of fish when separated from their own kind. © 2012 Phys.org Image: Macquarie University (Phys.org) — Researchers in Australia have discovered that mourning cuttlefish (Sepia plangon) have the unique property of being able to change the coloring on one side of their body to mimic the coloring of a female to fool rivals, while displaying typically male coloring on the side that a nearby female sees; all at the same time. The team, led by Culum Brown at Macquarie University first noticed the sly behavior in a large test tank. Subsequent research showed that the ploy was prevalent in the wild as well. The team has had their paper describing their findings published in the journal Biology Letters. More information: It pays to cheat: tactical deception in a cephalopod social signalling system, Biology Letters, Published online before print July 4, 2012, doi: 10.1098/rsbl.2012.0435AbstractSignals in intraspecific communication should be inherently honest; otherwise the system is prone to collapse. Theory predicts, however, that honest signalling systems are susceptible to invasion by cheats, the extent of which is largely mediated by fear of reprisal. Cuttlefish facultatively change their shape and colour, an ability that evolved to avoid predators and capture prey. Here, we show that this ability is tactically employed by male mourning cuttlefish (Sepia plangon) to mislead conspecifics during courtship in a specific social context amenable to cheating 39 per cent of the time, while it was never employed in other social contexts. Males deceive rival males by displaying male courtship patterns to receptive females on one side of the body, and simultaneously displaying female patterns to a single rival male on the other, thus preventing the rival from disrupting courtship. The use of tactical deception in such a complex communication network indicates that sociality has played a key role in the cognitive evolution of cephalopods. Citation: Researchers discover cuttlefish able to mimic female on half its body (w/ Video) (2012, July 4) retrieved 18 August 2019 from https://phys.org/news/2012-07-cuttlefish-mimic-female-body-video.html Cuttlefish have high definition polarization vision, researchers discover Explore further
The 8-cm-long silica-on-silicon photonic chip in the center of the picture served as the 4-photon QBSM. Arrays of single-mode fibers are glued to the left and right sides of the chip. For viewing purposes, a red laser is coupled into two of the single mode fibers (right side of picture), which illuminate a portion of the on-chip interferometric network. For the boson sampling experiment, the red laser was replaced with single photon sources. There are five thermal phase shifting elements on top of the chip, though they were not used in this experiment. This image relates to the paper by Dr. Spring and colleagues. Credit: Dr. James C. Gates Explore further , Science While interest remains high in creating a true quantum computer, thus far, real world results have been less than promising. Because of that, some experts in the field have suggested that perhaps what’s needed is a new way of looking at the problem. MIT’s Scott Aaronson, for example, has suggested that rather than trying to start by building a quantum computer from the ground up, a better approach might be to build specialty devices that solve just one type of problem. He has suggested that a Galton board created using quantum mechanics principles should be possible. In response, several research teams around the globe have been trying to do just that.Quantum versions of the Galton board take the form of a board that uses photons instead of wooden balls and pegs and are named after the family of particles to which they belong: bosons. The sampling devices work much the same as the Victorian models except in one important way. When a photon in the sampler meets another photon, both must go left, or right – in the real-world physical board, balls can go individually either way on their own. The result should be a device that can calculate far faster than any conventional computer. Using such a setup, one team, led by Justin Spring, has built a sampler capable of computing the permanent of a matrix. Another led by Matthew Broome, has sent three photons through a maze that describe a 6 node optical circuit.What’s perhaps most compelling about the work being done by all of the teams in this area is the promise of scalability. Not in making the boards or balls bigger, but in making the samplers more and more complex by adding more ways that the photons can be manipulated as they move through the device. Theoretically, doing so offers the promise of a universal computer capable of performing limitless numbers of applications. Whether it will be possible to construct such complex devices in the real world however, remains to be seen. Journal information: arXiv © 2012 Phys.org (Phys.org)—Separate teams working on boson samplers report progress in separate papers uploaded to the preprint server arXiv and in the journal Science. Each relate the progress being made in developing a quantum version of a Victorian era Galton board – where balls are dropped across a peg board resulting in the representation of a binomial distribution at the bottom. Chinese team builds first quantum router More information: Photonic Boson Sampling in a Tunable Circuit, Science, DOI: 10.1126/science.1231440ABSTRACTQuantum computers are unnecessary for exponentially efficient computation or simulation if the Extended Church-Turing thesis is correct. The thesis would be strongly contradicted by physical devices that efficiently perform tasks believed to be intractable for classical computers. Such a task is boson sampling: sampling the output distributions of n bosons scattered by some linear-optical unitary process. Here, we test the central premise of boson sampling, experimentally verifying that 3-photon scattering amplitudes are given by the permanents of submatrices generated from a unitary describing a 6-mode integrated optical circuit. We find the protocol to be robust, working even with the unavoidable effects of photon loss, non-ideal sources, and imperfect detection. Scaling this to large numbers of photons will be a much simpler task than building a universal quantum computer.Boson Sampling on a Photonic Chip, Science, DOI: 10.1126/science.1231692ABSTRACTWhile universal quantum computers ideally solve problems such as factoring integers exponentially more efficiently than classical machines, the formidable challenges in building such devices motivate the demonstration of simpler, problem-specific algorithms that still promise a quantum speedup. We construct a quantum boson sampling machine (QBSM) to sample the output distribution resulting from the nonclassical interference of photons in an integrated photonic circuit, a problem thought to be exponentially hard to solve classically. Unlike universal quantum computation, boson sampling merely requires indistinguishable photons, linear state evolution, and detectors. We benchmark our QBSM with three and four photons and analyze sources of sampling inaccuracy. Scaling up to larger devices could offer the first definitive quantum-enhanced computation.Arxiv papers: arxiv.org/abs/1212.2783 and arxiv.org/abs/1212.2240 Citation: Boson samplers offering promise for new kinds of computing devices (2012, December 21) retrieved 18 August 2019 from https://phys.org/news/2012-12-boson-samplers-kinds-devices.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.
Journal information: Physical Review Letters Citation: Magnetic shell provides unprecedented control of magnetic fields (2013, January 4) retrieved 18 August 2019 from https://phys.org/news/2013-01-magnetic-shell-unprecedented-fields.html Magnetic shells can be used to increase the magnetic energy of multiple magnets: The four magnetic dipoles in (a) interact very weakly, even when they are moved closer together in (b). However, when all four dipoles are surrounded by a shell as in (c), their exterior fields become enhanced, yielding a stronger magnetic field in the center region. Credit: Carles Navau, et al. ©2012 American Physical Society Explore further The newly designed magnetic shell can either expel or concentrate magnetic energy. In the left panels, a small dipole magnet in (a) is surrounded by a magnetic shell in (b), which expels its magnetic energy further outward. In (c), a second shell harvests the energy and concentrates it into its center hole; in this way, magnetic energy is transferred through empty space. In the right panels, two dipole magnets in (d) are surrounded by shells in (e) that expel their magnetic energy. As shown in (f), the result is magnetic coupling between the two dipoles. Credit: Carles Navau, et al. ©2012 American Physical Society The physicists, Carles Navau, Jordi Prat-Camps, and Alvaro Sanchez at the Autonomous University of Barcelona in Spain, have published their results on their new method of magnetic energy distribution and concentration in a recent issue of Physical Review Letters.”We have tried with this work to open new ways of shaping magnetic fields in space,” Sanchez told Phys.org. “Since magnetic fields are so crucial for so many technologies (e.g., almost 100% of the energy generated uses magnetic fields), finding these new possibilities may bring benefits.”The basis of the technique lies in transformation optics, a field that deals with the control of electromagnetic waves and involves metamaterials and invisibility cloaks. While researchers have usually focused on using transformation optics ideas to control light, here the researchers applied the same ideas to control magnetic fields by designing a magnetic shell with specific electromagnetic properties. The shell can be used to control magnetic fields in two ways, depending on its location relative to a magnetic source. When a magnetic source is placed inside the shell, the shell expels the magnetic energy outside. When the shell is placed near a magnetic source located outside the shell, the shell harvests and concentrates the magnetic energy from the source into a hole in the shell’s center. For practical purposes, this approximation is sufficient to work for a variety of potential applications, in which the magnetic shell’s two functions (transferring and concentrating) can be used together or independently. For instance, by surrounding two magnetic dipoles with their own shells, the magnetic coupling between them can be enhanced, which could be used to improve the efficiency of wireless power transmission between a source and a receiver.With its ability to concentrate nearby magnetic fields, a single magnetic shell could also be used to increase the sensitivity of magnetic sensors. The scientists demonstrated that a magnetic sensor placed inside the shell can detect a much larger magnetic flux from an external magnetic source than it would when using a typical concentration strategy involving superconductors. Magnetic sensors are often used in consumer electronics, factory automation, navigation, and many other areas. The magnetic shell could also have medical applications, such as for biosensors that measure the brain’s response in magnetoencephalography, a technique used for mapping brain activity. The physicists also showed that the shells can be used to surround multiple magnetic sources arranged in a circle, allowing them to concentrate magnetic energy in the center of the circle. This arrangement could be used in transcranial magnetic stimulation (TMS), a technique used to treat psychiatric disorders. While TMS generally targets regions near the brain’s surface, the magnetic shells could help extend the reach of magnetic fields to deeper targets.Magnetic energy also plays a vital role in power applications, such as in power plants, magnetic memories, and motors. All of these applications require magnetic energy to be spatially distributed or concentrated in a certain way. By enabling the control of magnetic energy in new ways, the magnetic shells could improve these applications and others due to their many possible configurations.”We are presently working on extending these ideas of applying transformation optics to the magnetic case into different directions, and see how future designs can be implemented in practice (in the present case, we suggested superconductors and ferromagnetic materials as a practical implementation of the magnetic shell),” Sanchez said. Complexity in core-shell nanomagnets 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: Carles Navau, et al. “Magnetic Energy Harvesting and Concentration at a Distance by Transformation Optics.” PRL 109, 263903 (2012). DOI: 10.1103/PhysRevLett.109.263903 Copyright 2013 Phys.org All rights reserved. This material may not be published, broadcast, rewritten or redistributed in whole or part without the express written permission of Phys.org. In both cases, the shell works by dividing the space into an exterior and interior zone and then transferring the magnetic energy completely into one domain or the other. This method differs from the way that superconductors and ferromagnets distribute magnetic energy, where the energy always returns to the domain where the magnetic sources are.Although no material exists that can perfectly meet the requirements for the magnetic shell’s properties, the physicists showed that they could closely approximate these properties by using wedges of alternating superconducting and ferromagnetic materials. (Phys.org)—A general property of magnetic fields is that they decay with the distance from their magnetic source. But in a new study, physicists have shown that surrounding a magnetic source with a magnetic shell can enhance the magnetic field as it moves away from the source, allowing magnetic energy to be transferred to a distant location through empty space. By reversing this technique, the scientists showed that the transferred magnetic energy can be captured by a second magnetic shell located some distance away from the first shell. The second shell can then concentrate the captured magnetic energy into a small interior region. The achievement represents an unprecedented ability to transport and concentrate magnetic energy, and could have applications in the wireless transmission of energy, medical techniques, and other areas.
Explore further (Phys.org) —Scientists have a great deal of evidence to support the fact that the universe contains much more baryonic matter than baryonic anti-matter, a phenomenon known as baryon asymmetry. Baryons, which are defined as being made of three quarks, include protons and neutrons and make up the bulk of the atomic matter that we’re familiar with in everyday life. But much less is known about the possibility of a lepton asymmetry, in which there are unequal amounts of leptons and anti-leptons in the universe. The best known examples of leptons are electrons and neutrinos. Neutrinos in particular are much harder to detect than baryons because they’re much lighter, and so much less energetic. Citation: Observations of early universe hint at a giant excess of anti-neutrinos (2013, March 21) retrieved 18 August 2019 from https://phys.org/news/2013-03-early-universe-hint-giant-excess.html More information: Dominik J. Schwarz and Maik Stuke. “Does the CMB prefer a leptonic Universe?” New Journal of Physics. 15 (2013) 033021. DOI: 10.1088/1367-2630/15/3/033021 Journal information: New Journal of Physics 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. Copyright 2013 Phys.org All rights reserved. This material may not be published, broadcast, rewritten or redistributed in whole or part without the express written permission of Phys.org. Nine year WMAP image of background cosmic radiation (2012) Credit: NASA Could dark baryons explain dark matter? In a new study, physicists Dominik J. Schwarz and Maik Stuke at Bielefeld University in Germany have published a paper in the New Journal of Physics in which they show that recent data from cosmic microwave background (CMB) experiments suggests that the universe contains an excess of anti-neutrinos (defined by their opposite chirality rather than opposite charge) compared with normal neutrinos. Further, this lepton asymmetry could potentially exceed the baryon asymmetry, which is 10-10, by several orders of magnitude. The total number of leptons could also exceed the total number of baryons in the universe.”A ‘leptonic universe’ is a universe that contains many more leptons than baryons,” Schwarz told Phys.org. “A universe with a vast amount of anti-neutrinos in it would be something unexpected. I can’t say how it would change the overall picture, as we are just at the beginning to explore this idea.”Finding evidence for a lepton asymmetry is not easy. For one thing, leptons have such low energy that large numbers of them can easily hide in the neutrino background and escape scientists’ attempts to detect them. But, as Schwarz and Stuke explain, leptons could be observable in the early universe because they would have affected nucleosynthesis (the production of nuclei that occurred just a few moments after the Big Bang) and the CMB (the radiation left over from the photon decoupling that occurred when the universe was about 400,000 years old).In particular, leptons would have affected the production of helium in the early universe. In this study, the physicists measured the abundance of primordial helium in the universe using new CMB data from three sources: the Atacama Cosmology Telescope, the Southpole Telescope, and the WMAP Team. By comparing the results of this global analysis with previous results of helium abundance from local observations of extragalactic regions, the scientists could put some constraints on lepton asymmetry. The data indicated that we may live in a universe ruled by anti-neutrinos instead of normal ones, which could have implications for how we currently understand what happened in the early universe. In addition, the anti-neutrino surplus would theoretically lead to an increase in the expansion rate of the universe. However, the data so far does not rule out the standard scenario of Big Bang nucleosynthesis. “With regard to Big Bang Nucleosynthesis, [confirmed lepton asymmetry] would certainly falsify the standard scenario, which assumes that there is no lepton asymmetry,” Schwarz said. “However, the new model for nucleosynthesis would not be radically different; it would just incorporate this new ingredient.”In the future, the physicists hope that upcoming CMB data releases and improved measurements of primordial abundances will allow for further testing of lepton asymmetry. “I think it would be surprising if the asymmetry in leptons turns out to be much larger than the asymmetry in baryons,” Schwarz said. “Although in some sense, we should honestly admit that we don’t know how the matter anti-matter asymmetry comes along. Thus we should not be surprised but rather open-minded.”
Journal information: Proceedings of the National Academy of Sciences © 2013 Phys.org Explore further Yangtze River’s ancient origins revealed More information: Pre-Miocene birth of the Yangtze River, PNAS, Published online before print April 22, 2013, doi: 10.1073/pnas.1216241110AbstractThe development of fluvial systems in East Asia is closely linked to the evolving topography following India–Eurasia collision. Despite this, the age of the Yangtze River system has been strongly debated, with estimates ranging from 40 to 45 Ma, to a more recent initiation around 2 Ma. Here, we present 40Ar/39Ar ages from basalts interbedded with fluvial sediments from the lower reaches of the Yangtze together with detrital zircon U–Pb ages from sand grains within these sediments. We show that a river containing sediments indistinguishable from the modern river was established before ∼23 Ma. We argue that the connection through the Three Gorges must postdate 36.5 Ma because of evaporite and lacustrine sedimentation in the Jianghan Basin before that time. We propose that the present Yangtze River system formed in response to regional extension throughout eastern China, synchronous with the start of strike–slip tectonism and surface uplift in eastern Tibet and fed by strengthened rains caused by the newly intensified summer monsoon. Citation: New research suggests Yangtze River is at least 23 million years old (2013, April 23) retrieved 18 August 2019 from https://phys.org/news/2013-04-yangtze-river-million-years.html Topographic map of East Asia, showing major rivers and the locations mentioned in the text. SBSYB, Subei–South Yellow Sea Basin; BHB, Bohai Basin; ECSB, East China Sea Basin; PRB, Pearl River Mouth Basin; YB, Yinggehai Basin; SPG, Songpan Garze; QB, Qiangtang Block. Red circles show locations of Yellow River samples (31). Major faults marked are taken from Replumaz and Tapponnier (59). Credit: (c)2013 PNAS, Published online before print April 22, 2013, doi: 10.1073/pnas.1216241110 (Phys.org) —An exhaustive study conducted by a combined team of Chinese, Japanese, American and Australian researchers has found that the third longest river in the world, the Yangtze, located in China, is at least 23 million years old, but no older than 36.5 million years old. The team describes their research and results in their paper they’ve had published in the Proceedings of the National Academy of Sciences. The Yangtze (Long River, in Chinese) has a long and varied history, going back thousands of years. But until now, no one has been able to say just how long the river has been in existence. To find out, the researchers studied Lower Miocene sediments and compared them with sediments that came about in modern times. They found virtually no differences between the two which the teams suggests, means that a river very much like the one that exists today, existed as far back as 23 million years ago. The river flows from the mountainous glaciers of the Tibetan plateau 3,988 miles across China to the East China Sea at Shanghai and is responsible for draining a fifth of the runoff that occurs in that country.Most research to date has suggested that the river changed direction during an uplifting of the Tibetan Plateau following an India-Eurasian plate collision millions of years ago. Still, estimates of the river’s age have varied from 45 million years ago, to just 2 million years ago. To get a better estimate, the team studied rocks taken from the Jianghan Basin, downstream from the Three Gorges Dam. The rocks there were virtually indistinguishable from rocks found in the modern era, and because such rocks can only form in the presence of moving water, the researchers concluded that the river must have existed in close to its present state, approximately 23 million years ago—the age of the rocks they examined. And because no such rocks could be found that were dated older than 36.5 million years, the researchers used that number to estimate the earliest possible date of formation of the river.The researchers note that their estimation of the age of the river coincides with both the Tibatan Plateau uplifting timeframe and a permanent increase in summer monsoon rains, which would of course have fed more water to the river contributing to both its size and the path it forged to the sea. 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.
© 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. In other news, Steven Dick, an astronomer with ties to the Library of Congress, stirred interest in and out of the science community by openly asking the question: How would the world change if we found extraterrestrial life? Scientists would be thrilled of course, he notes, but how would everyone else react? Seems reasonable to ponder the implications since we are trying so hard to find it. Meanwhile another team of deep thinkers has been looking into how countries treat one another when oil is at stake and their study showed that crude conspiracy theories could be right—the need for energy does appear to be a justification for some countries interfering with the running of other countries. And while it might be difficult to find a good use for it, a combined team of chemists from the U.S. and Australia found a way to unboil eggs—at least the whites. The work is actually part of learning how to pull apart tangled proteins and letting them refold, which could have a big impact on the medical and food industries. Also a team of researchers in the U.S. found a higher dementia risk can be linked to more use of common medications and a group of paleontologists unearthed a long-necked “dragon” in China—it is actually a dinosaur, of course.And finally, if you are a Craigslist user you might be interested in knowing that a team of researchers at the University of Minnesota recently uncovered a connection between Craigslist personal ads and HIV trends. They do not attempt to explain why the advent of Craigslist has led to a 15.9 percent increase in reported HIV cases, but the assumption seems to be that the site promotes risky hookups. Citation: Best of Last Week – Popper’s experiment realized again, unboiling eggs and the connection between Craigslist and HIV (2015, February 2) retrieved 18 August 2019 from https://phys.org/news/2015-02-week-popper-unboiling-eggs-craigslist.html Explore further A ‘Fermi surface’ is kind of three-dimensional map representing the collective energy states of electrons in a material. These computer-generated illustrations show how the Fermi surface for CeRhIn5 changes, depending upon whether the electrons are strongly interacting (left) or weakly interacting (right). Credit: Q. Si/Rice University and J.X. Zhu/Los Alamos National Laboratory (Phys.org)—It was an interesting week for physics as Popper’s experiment was realized again, by a different team this time, using a different approach, causing physicists to wonder what it actually means because the results still do not violate the uncertainty principle. Also in an international effort, a team found that evidence is mounting for quantum criticality theory which suggests that some odd electronic behavior can be attributable to quantum fluctuations of strongly correlated electrons. Another team at the University of California used the idea of a quantum computer as a detector to show that space is not squeezed—confirming the assumption, based on the theory of special relativity, that space looks the same in all directions. Research uncovers connection between Craigslist personals, HIV trends
How are we to think of how we think? Are our minds a separate internal world in which we manipulate mere proxies—symbols, ideas, representations—for real things? Are they software running in the brain whose connection to the real, “external” world is then a further mystery in need of explanation? Or is it rather that we are embodied all the way down, such that even our most abstract thoughts—about mathematics, say, or relations between ideas—are still creatures of our creaturely nature? In “Mind in Motion,” the distinguished cognitive scientist Barbara Tversky makes the case that our embodiment as living, acting creatures is no mere add-on to our problem-solving cognitive capacities. Rather, she argues, the fact that we live and move and act in a physical world is fundamental, in very particular ways, to the very nature of our thought. Moving beyond theory, she draws lessons about how to design education, our environment and our problem-solving strategies to help us to live and think better. Read the whole story: The Wall Street Journal
Blooming Tree school, Janakpuri celebrated its fifth Annual Day with great fervour on December 21 at Dr. Sarvapalli Radhakrishnan Auditorium, Delhi Cantonment. The function commenced with Ganesh Vandana and lighting of the lamp by the chief guest and eminent educationist, Lata Vaidyanathan, Former Principal, Modern School, Barakhamba Road, Member, Governing Body of CBSE and Director of Teri Prakriti School, Gurgaon.250 students aged between 2 to 4 years performed at the event, which was a colourful extravaganza of music, dance and drama with foot tapping music and enthralling dance sequences. The children looked resplendent in their colourful costumes. The musical production titled Joy Ride was a story about a boy who never stopped dreaming and whose dream was finally fulfilled. The play concluded with the words of Walt Disney that ‘Dreams do come true for those who have the courage to pursue them’. The chief guest and parents were overwhelmed by the mesmerizing performances of the children. The children were given a standing ovation by the audience. Parents and grandparents lauded the efforts of the staff and students.
Delhi Police Commissioner B S Bassi on Friday hinted that Congress MP Shashi Tharoor will be questioned “soon” by the Special Investigation Team (SIT) which is probing the mysterious death case of his wife Sunanda Pushkar.“I think in the next couple of days, all the key persons who have to be questioned by us will be questioned. We would like to complete it soon. I think the SIT will soon do it,” he told reporters here today outside Police Headquarters when asked when would Tharoor be questioned in the case. He also denied reports that the viscera samples which are almost one-year-old must have been spoilt by now and would not reveal the kind of poison that caused Sunanda’s death even if it is sent abroad.