Month: August 2019 Page 1 of 17

All languages may originate from Africa study

first_img Previous language trees only go back as far as 9,000 years and linguists have believed that language was not able to be traced farther back than that. However, Atkinson’s claims could have language going back as far as 100,000 years.In Atkinson’s study he looks, not at words, but at phonemes which are the consonants, vowels and tones which make up language. By applying mathematical methods, he has discovered a pattern within the more than 500 languages throughout the world.He has discovered that the farther humans had to travel from Africa, the less phonemes their language used. When looking at African based languages, some have more than 100 phonemes as a base. The English language only has around 45. Travel even further on the migration route, and you find Hawaiian with only 13 phonemes.These findings correlate well with the fossil and DNA evidence that modern humans originated in Africa. When it comes to genetic diversity in humans, there is also an established pattern of decreasing diversity the greater the distance from Africa. Because of this, it was not a surprise that language would follow in that same decreasing pattern. ( — Published in Science, a new report from biologist Quentin D. Atkinson from the University of Auckland is sparking controversy among linguists. Atkinson has been analyzing the sounds of the many languages around the world and has detected signals that lead to southern Africa as a place where all human language began. Use it or lose it? Study suggests the brain can remember a ‘forgotten’ language Citation: All languages may originate from Africa: study (2011, April 15) retrieved 18 August 2019 from More information: Phonemic Diversity Supports a Serial Founder Effect Model of Language Expansion from Africa, Science 15 April 2011: Vol. 332 no. 6027 pp. 346-349 DOI: 10.1126/science.1199295center_img © 2010 Explore further This document is subject to copyright. Apart from any fair dealing for the purpose of private study or research, no part may be reproduced without the written permission. The content is provided for information purposes only.last_img read more

Cane toad pioneers speed up invasions

first_img Journal information: Proceedings of the National Academy of Sciences Citation: Cane toad pioneers speed up invasions (2013, July 30) retrieved 18 August 2019 from This document is subject to copyright. Apart from any fair dealing for the purpose of private study or research, no part may be reproduced without the written permission. The content is provided for information purposes only. Explore further Associate Professor Rick Shine: “The research has implications for how we assess the impact of invasive species.” © 2013 Phys.orgcenter_img More information: Rapid shifts in dispersal behavior on an expanding range edge, PNAS, Published online before print July 29, 2013, doi: 10.1073/pnas.1303157110AbstractDispersal biology at an invasion front differs from that of populations within the range core, because novel evolutionary and ecological processes come into play in the nonequilibrium conditions at expanding range edges. In a world where species’ range limits are changing rapidly, we need to understand how individuals disperse at an invasion front. We analyzed an extensive dataset from radio-tracking invasive cane toads (Rhinella marina) over the first 8 y since they arrived at a site in tropical Australia. Movement patterns of toads in the invasion vanguard differed from those of individuals in the same area postcolonization. Our model discriminated encamped versus dispersive phases within each toad’s movements and demonstrated that pioneer toads spent longer periods in dispersive mode and displayed longer, more directed movements while they were in dispersive mode. These analyses predict that overall displacement per year is more than twice as far for toads at the invasion front compared with those tracked a few years later at the same site. Studies on established populations (or even those a few years postestablishment) thus may massively underestimate dispersal rates at the leading edge of an expanding population. This, in turn, will cause us to underpredict the rates at which invasive organisms move into new territory and at which native taxa can expand into newly available habitat under climate change. Cane toads ‘wiping out’ mini crocodiles Down Under ( —Climate change is one of a number of stressors that cause species to disperse to new locations. Scientists must be able to predict dispersal rates accurately, as the movement of a new species into an area can have a significant, and sometimes detrimental, effect on that area’s ecology. When studying dispersal rates of cane toads in Australia, Tom Lindstrom of the University of Sydney and his colleagues found that toads that are first to move into a new area travel at faster rates than toads that arrive later. Their research, published in the Proceedings of the National Academy of Sciences, shows that failure to account for this has caused scientists to severely underestimate dispersal rates. Australia’s Bureau of Sugar Experiment Stations brought cane toads from America to Australia in 1935, in order to control beetles that were infesting sugar cane. Since then, cane toad populations have spread widely, and the toads, which secrete a toxin, disrupt the native ecology. In order to predict how cane toad populations will shift in response to environmental stressors, scientists have been studying movement patterns of established toad populations. Lindstrom and his team contend that by ignoring the differences between “pioneer” toads, who are the first to enter a site, and toads that have been at a site for a few years, previous predictions of dispersal rates have been inaccurate.The team studied eight years worth of data from radio-tracked toads that had colonized a site in tropical Australia. Using a Bayesian model, the researchers analyzed the data and determined that pioneer toads were more likely move in constant directions and take long steps than toads that arrived a few years later. These toads tended to take short steps and frequently make sharp-angled turns. Because of these behavioral differences, toads at the forefront of an invasion covered almost twice as much ground as later-arriving toads.The team found physical differences between the pioneer toads and the other toads that could account for the pioneers’ faster movements. For example, pioneer toads had longer legs. The researchers speculate that because pioneers can only mate with each other, inherited physical differences between pioneers and other toads increase over time. This causes pioneers to continually become more “athletic” in comparison to the other toads. In fact, many of the cane toad pioneers had spinal arthritis, indicating that they had reached physiological or biomechanical tolerance limits. Lindstrom and his team suggest that environmental conditions may enhance the effects of physical “improvements” in pioneer populations; for example, pioneers may find travel during wet seasons easier than their slower conspecifics.The researchers claim that many other species have exhibited rapid dispersal rates during the earliest phases of invasions. By restricting data to that obtained from organisms long-established in an area and ignoring variations in environmental conditions, scientists may routinely be underestimating the speeds at which species can invade new territories.last_img read more

New mass spectrometry technique studies kinetics of fast reactions

first_img More information: “Microdroplet fusion mass spectrometry for fast reaction kinetics” Jae Kyoo Lee, Samuel Kim, Hong Gil Nam, and Richard N. Zare, PNAS, investigated the fusion of high-speed liquid droplets as a way to record the kinetics of liquid-phase chemical reactions on the order of microseconds. Two streams of micrometer-size droplets collide with one another. The droplets that fused (13 μm in diameter) at the intersection of the two streams entered the heated capillary inlet of a mass spectrometer. The mass spectrum was recorded as a function of the distance x between the mass spectrometer inlet and the droplet fusion center. Fused droplet trajectories were imaged with a high-speed camera, revealing that the droplet fusion occurred approximately within a 500-μm radius from the droplet fusion center and both the size and the speed of the fused droplets remained relatively constant as they traveled from the droplet fusion center to the mass spectrometer inlet. Evidence is presented that the reaction effectively stops upon entering the heated inlet of the mass spectrometer. Thus, the reaction time was proportional to x and could be measured and manipulated by controlling the distance x. Kinetic studies were carried out in fused water droplets for acid-induced unfolding of cytochrome c and hydrogen–deuterium exchange in bradykinin. The kinetics of the former revealed the slowing of the unfolding rates at the early stage of the reaction within 50 μs. The hydrogen–deuterium exchange revealed the existence of two distinct populations with fast and slow exchange rates. These studies demonstrated the power of this technique to detect reaction intermediates in fused liquid droplets with microsecond temporal resolution. (—As chemical reactions proceed, the reactants combine to form intermediates and those short-lived intermediates eventually become products. Reaction kinetics is concerned with how long it takes for the reaction mechanism, from reactants to intermediates to products, to progress. Often, it is the intermediates that provide clues to what pathway the reaction follows, but these intermediates are typically difficult to study in fast reactions. Synthesis and characterization of an important intermediate for biocatalysts They, then, wanted to test if the reaction stops at the inlet and whether they can discern rate data from a reaction with a known kinetic profile. They used 2, 6-dichlorophenolindophenol (DCIP) and ascorbic acid, which have been extensively studied to measure reaction rates in the liquid phase. This reaction behaves as a pseudo-first-order system, provided that one reagent is in excess concentration compared to the other. Their study confirmed that the reaction stopped upon entering the heated inlet of the mass spectrometer. They also found that droplet mixing was nearly complete at 0.7mm with a measured rate constant of approximately 1.0 x 105 s-1. This rate is much faster than what has been measured in bulk solution, indicating differences in chemical behavior in bulk solution verses a droplet.The next test was to see if their technique could study the kinetics of protein unfolding. Mass spectrometry has been used to provide information on protein folding by looking at changes in the charged states, but if a protein undergoes structural changes very quickly, a slower technique would miss the initial intermediate states. The authors used cytochrome c as their model system. It unfolds in acid. They observed the typical states for cytochrome c unfolding, but they also observed additional intermediate charge states occurring on the microsecond scale.Finally, Lee et al. looked at the hydrogen-deuterium exchange rate in bradykinin, a peptide with nine amino acids. They observed a gradual increase in mass as deuterium replaced hydrogen in the peptide. This technique is often used to discern higher-order structural changes in proteins and peptides because certain hydrogens are more prone to deuterium change than others. They observed a rapid deuterium exchange until approximately 17 microseconds, followed by three slow deuterium exchanges at 30 microseconds.While the reactions that occur at the microdroplet scale do not precisely mimic those in bulk solution, they still progress through the same major reaction pathway. This experiment has shown that microdroplet mixing coupled with mass spectrometry may be a robust tool for discerning the intermediate components and kinetics of fast reactions in the liquid phase. Journal information: Proceedings of the National Academy of Sciences Schematic (not to scale) of experimental setup for studying reaction kinetics in fused droplets. (Inset) The definition of the droplet fusion center, which is the intersection of the two droplet streams. Most fusion events take place in a circle (dotted black) of about 500 μm surrounding the droplet fusion center. Credit: (c)2015 Jae Kyoo Lee, Samuel Kim, Hong Gil Nam, and Richard N. Zare, PNAS, DOI: 10.1073/pnas.1503689112 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 order to study reaction intermediates of fast reactions, scientists need to address two problems: 1) the time it takes to mix two reactants in bulk solutions, or the diffusion-limiting mixing times, and 2) finding a method that can analyze reaction components microseconds after the reaction begins. Jae Kyoo Lee, Samuel Kim, Hong Gil Nam, and Richard N. Zare from Stanford University and the Institute for Basic Sciences and DGIST and in Daegu, Republic of Korea developed a new method that overcomes these two limiting factors for analyzing fast reactions using a combination of a microdroplet fusion technique and mass spectrometry. Their research appears in the Proceedings of the National Academy of Sciences.Prior studies have used fused microdroplets as a way to mix reactants in several hundred microseconds. It is possible to get even faster mixing times by making the microdroplets smaller and colliding them at a faster speed. While this technique has been used for fast mixing times, it has never been used for kinetic measurements. Lee et al developed a droplet generation and fusion platform and combined it with mass spectrometry, which can detect small amounts of substance quickly, to investigate reaction kinetics at on the microsecond scale.In order to obtain data on how the reaction is progressing, the authors need to ensure that the mass spectrometer is measuring the components of the reaction at a various time points as the reaction progresses. Other studies had shown that many liquid reactions stop progressing once they enter the mass spectrometer inlet and become gaseous ions. If this is the case, then varying the distance between microdroplet fusion and the mass spectrometer inlet would make reaction progress a function of length. With knowledge of the average velocity of the droplet, these measurements can then be converted to a function of time. Explore further 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 Play Colored dots and lines indicating tracked droplets were overlaid. Credit: Jae Kyoo Lee, PNAS, doi: 10.1073/pnas.1503689112 To test their technique, Lee et al. first looked at pure water droplets. They used a high-speed camera to characterize droplet generation, fusion, and velocity. They determined that evaporation of the pure water droplets was negligible, maintaining nearly constant droplet sizes. They were able to make droplets on the order of 13 micrometers and 93% of fusion occurred approximately within 500 micrometers from the center point of combination. This defined the distance for the start of the reaction time for subsequent studies. Citation: New mass spectrometry technique studies kinetics of fast reactions (2015, March 24) retrieved 18 August 2019 from © 2015 Phys.orglast_img read more

Researchers generate 3D images using just one photon per pixel w video

first_img Explore further Citation: Researchers generate 3D images using just one photon per pixel (w/ video) (2016, July 13) retrieved 18 August 2019 from Play Video comparing the new algorithm with a conventional filtered-histogram method. As the number of detected photons decreases, the new method substantially outperforms the conventional method in both reflectivity and depth reconstructions. Credit: Shin et al. By requiring vastly fewer photons than conventional cameras, single-photon cameras have potential applications in low-light conditions, such as biological imaging, astronomy, and providing 3D vision for self-navigating advanced robotic systems, such as unmanned aerial vehicles and exploration rovers.In the future, the researchers plan to pursue various applications by collaborating with researchers with different specialties. Working with MIT’s chemistry department, for example, they have begun to apply their photon-efficient approach to fluorescence imaging, an imaging modality that has many applications in biology. They are also pushing the technology to its limits under DARPA sponsorship as part of DARPA’s Revolutionary Enhancement of Visibility by Exploiting Active Light-fields (REVEAL) program. REVEAL’s goal is to use all the information available in the light field to see into occluded spaces without using mirrors.”We’re going to use laser light and single-photon detection to see around a corner,” Shapiro explained. “Our approach will rely on diffuse reflections from a wall. Because the light returned from the hidden objects will be very weak, photon efficiency is essential.” The researchers, led by Jeffrey Shapiro, a professor of electrical engineering and computer science at the Massachusetts Institute of Technology (MIT), along with coauthors at MIT, Politecnico di Milano, and Boston University, have published a paper on the new photon-efficient approach to imaging with a single-photon camera in a recent issue of Nature Communications.”Our work shows that we can use these new photon-counting cameras at much lower fluxes and much higher efficiencies than previously thought,” Shapiro told to other camera-based 3D imaging techniques that have recently been developed, the new framework has the highest photon efficiency to date, resulting in a visibly better reconstruction accuracy and an order of magnitude better depth resolution. To demonstrate how the new single-photon imaging algorithm works in low-light environments, the researchers illuminated a scene of interest (such as a mannequin and sunflower) with a pulsed laser that emits low-light pulses every 50 nanoseconds. A light diffuser spatially spreads out the pulses so that they flood the entire scene. Play Video showing the three stages of the reconstruction algorithm. Credit: Shin et al. A single-photon camera then captures the light reflected by the illuminated objects, along with some background light that the researchers added to simulate a realistic environment. The key element of the camera is a single-photon avalanche diode (SPAD) array, which detects incoming photons and records their precise times of arrival. In order to reconstruct a scene from a very small number of detected photons, the new algorithm accounts for the fact that a scene’s features are statistically correlated. Whereas most camera systems treat each pixel independently, the new algorithm recognizes that neighboring pixels often have strong spatial correlations, which are punctuated by sharp boundaries that separate two different features (such as the mannequin’s shirt and the sunflower in the test scene). By solving a mathematical problem of convex optimization, the new algorithm exploits these correlations to generate high-resolution 3D images using very few photons. Single-photon camera imaging set-up. Credit: Shin et al. © 2016 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 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: Dongeek Shin et al. “Photon-efficient imaging with a single-photon camera.” Nature Communications. DOI: 10.1038/ncomms12046 See more details at the researchers’ project page. (—Every time you take a photograph, your camera detects more than a billion photons. For a basic one-megapixel camera, that’s more than 1,000 photons per pixel. Now in a new study, researchers have developed an algorithm that is so efficient that it can generate high-quality 3D images using a single-photon camera that detects just one signal photon per pixel. Journal information: Nature Communications Creative Cameras exhibit explores light-in-flight imaging The images in this experiment have a final resolution of 384 x 384 pixels, and an average of one signal photon and one background light photon are detected per pixel.Another advantage of the new single-photon camera is that images can be captured very quickly, making it useful for applications that require fast and accurate imaging using extremely small amounts of light. 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 fullscreenlast_img read more

Astronomers discover Earthsized exoplanet with very short orbital period

first_img Explore further (—An international team of astronomers has detected a new Earth-sized exoplanet in an ultra-short period around its parent star. The alien world, designated EPIC 228813918 b, circles its host every four hours and 20 minutes, which makes it the second-shortest orbital period of a planet known to date. The finding was presented in a paper published July 14 on More information: EPIC 228813918 b: an Earth-sized planet in a 4.3-hour orbit around an M-dwarf, arXiv:1707.04549 [astro-ph.EP] report the discovery from K2 of a transiting terrestrial planet in an ultra-short-period orbit around an M3-dwarf. EPIC 228813918 b completes an orbit in only 4.3 hours, the second-shortest orbital period of any known planet, just 4 minutes longer than that of KOI 1843.03, which also orbits an M-dwarf. Using a combination of archival images, AO imaging, RV measurements, and light curve modelling, we show that no plausible eclipsing binary scenario can explain the K2 light curve, and thus confirm the planetary nature of the system. The planet, whose radius we determine to be 0.89 +/- 0.09 Earth radii, and which must have a iron mass fraction greater than 0.45, orbits a star of mass 0.463 +/- 0.052 Msol and radius 0.442 +/- 0.044 Rsol. EPIC 228813918 b was identified by a group of researchers led by Alexis Smith of German Aerospace Center’s (DLR) Institute of Planetary Research in Berlin, Germany. The transit signal was detected using NASA’s prolonged Kepler mission, known as K2, during its Campaign 10, lasting from July 6 to September 20, 2016.The planetary nature of this signal was confirmed by adaptive optics imaging, radial velocity measurements, light curve modeling and analysis of archival images, which excluded the possibility that the star EPIC 228813918 could be an eclipsing binary.For follow-up observations, the researchers used a variety of instruments, including the Infrared Camera and Spectrograph (IRCS) on the 8.2-m Subaru telescope at Mauna Kea, Hawaii, the HIRES instrument of the 10-m Keck I telescope, also on Mauna Kea, the NESSI imager on the 3.5-m WIYN telescope at the Kitt Peak National Observatory, Arizona, and the Andalucia Faint Object Spectrograph and Camera (ALFOSC) mounted at the NOT telescope of Roque de los Muchachos Observatory (La Palma, Spain).”We use its K2 light curve, radial velocities, archival images, adaptive optics imaging and a catalog of eclipsing binaries (EBs) to demonstrate that EPIC 228813918 is a transiting planetary system, and not an EB,” the paper reads.The newly found planet is slightly smaller than Earth (0.89 Earth radii). However, it’s extremely massive – its estimated maximum mass is 0.7 Jupiter masses. The exoplanet orbits an M-dwarf star nearly half the size and mass of our sun every 4.3 hours. The planetary system is located some 310 light years away from the Earth.The ultra-short orbital period of EPIC 228813918 b makes it the second shortest-orbital-period alien world discovered so far. The record holder is still KOI-1843 b (also orbiting an M-dwarf star), which has an orbital period just four minutes shorter than that of the newly detected planet.The researchers also managed to determine the chemical composition of EPIC 228813918 b. According to them, the planet has an iron core and a silicate mantle. The minimum iron mass fraction was found to be about 0.52, which is greater than that of Earth, Venus or Mars, but smaller than that of Mercury.The authors of the study concluded that the discovery of such extreme planetary systems like EPIC 228813918 is important for improving our knowledge about planet formation processes.”Discovering and characterizing extreme systems, such as ultra-short-period planets like EPIC 228813918, is important, as they offer constraints for planet formation theories. Furthermore, they allow us to begin to constrain their interior structure and potentially that of longer-period planets too, if they are shown to be a single population of objects,” the astronomers wrote in the paper. Citation: Astronomers discover Earth-sized exoplanet with very short orbital period (2017, July 19) retrieved 18 August 2019 from Archival images of EPIC 228813918, demonstrating its proper motion over nearly six decades. The images are from (i) 1954, (ii) 1992, and (iii) 2012. Each image is 50 by 50, and in each case North is up and East is to the left. The position of EPIC 228813918 (J2000 epoch) is indicated with a red reticle. The blue reticle in the leftmost panel indicates the position of the star used to determine the limiting magnitude of the image. The arbitrarily-positioned green rectangle in image (ii) indicates the size of the photometric aperture used by Vanderburg & Johnson (2014) to extract the flux of EPIC 228813918. The cyan (NE of target) and magenta (SE of target) reticles in image (ii) indicate the positions of EPIC 228814238 and EPIC 228813721, respectively. Credit: Smith et al., 2017. © 2017 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. New ‘hot Jupiter’ exoplanet detected by K2 missionlast_img read more

Two ways to improve optical sensing using different resonator techniques

first_img This document is subject to copyright. Apart from any fair dealing for the purpose of private study or research, no part may be reproduced without the written permission. The content is provided for information purposes only. Three teams find a way to measure frequencies with far better precision than previous techniques As Rechtsman notes, optical sensors are used in a variety of applications that involve very slight mechanical vibrations or changes in temperature. They are also used when working with nanoparticles or in the analysis of biomolecules. All such sensors have a single problem, however—their performance is limited by the strength of the perturbations under study. In this new effort, both research teams sought to overcome this limitation by coupling modes of light, allowing them to coalesce—this occurs in places called “exceptional points,” and they only arise in what are known as Hermitian systems. In such systems, prior research has shown, photon loss is a main feature, as opposed to conventional systems in which the opposite is true. In either case, the result is increased sensitivity, which, of course, translates to more precision.In the first effort, the researchers connected three ring-shaped sensors together and then added gold heating elements beneath them to fine tune the sensors and to emulate perturbations. In the second effort, the researchers used just one ring-shaped sensor but sent light around it in both directions (both clockwise and counterclockwise) at the same time to cause coalescence. Then, they used a fiber tip to fine tune the sensor and a second tip to cause perturbations.Both techniques come with a trade-off, Rechtsman notes, between fine-tuning and sensitivity, and there remains the question of whether either or both can be modified to achieve even higher sensitivities. Citation: Two ways to improve optical sensing using different resonator techniques (2017, August 10) retrieved 18 August 2019 from Structures called optical resonators trap light at certain frequencies. When the environment of such a resonator is perturbed, these frequencies shift, which allows optical resonators to be used as sensors. a, Hodaei et al. report a sensor that consists of three ring-shaped resonators that are coupled (red arrows). The authors use gold heating elements both to precisely tune the sensor and to emulate perturbations. b, By contrast, Chen et al. use a single toroidal resonator, and couple light that travels in clockwise (blue arrow) and anticlockwise (yellow arrow) directions. The authors use two fibre tips to tune the sensor and another type of tip to introduce perturbations. c, In conventional sensors, the shift in frequency caused by a perturbation is directly proportional to the strength of the perturbation (grey line). Hodaei et al. and Chen et al. demonstrate that the frequency shift in their sensing devices scales with the cube root (red line) or square root (blue line) of the perturbation strength, respectively. This leads to a dramatic improvement in the scaling of sensitivity of such sensors in comparison to conventional devices. Credit: Mikael C. Rechtsman, Nature 548, 161–162 (10 August 2017) doi:10.1038/548161a (—Two independent teams working on research aimed at improving optical sensing have used techniques that involve coupling two or more modes of light such that their modes and their corresponding frequencies coalesce, resulting in more sensitivity. In the first effort, a team from Washington University in St. Lois and Otto-von-Guericke University Magdeburg, in Germany, connected three traditional sensors for more precise tuning. In the second effort, a team from the University of Central Florida and Michigan Technological University used just one resonator but coupled light traveling in both directions around it. Both teams have published papers describing their efforts and results in the journal Nature. Mikael Rechtsman with the Pennsylvania State University offers a News & Views piece outlining optical sensing techniques and the work done by the two teams in the same journal issue.center_img Journal information: Nature © 2017 More information: 1. Weijian Chen et al. Exceptional points enhance sensing in an optical microcavity, Nature (2017). DOI: 10.1038/nature23281AbstractSensors play an important part in many aspects of daily life such as infrared sensors in home security systems, particle sensors for environmental monitoring and motion sensors in mobile phones. High-quality optical microcavities are prime candidates for sensing applications because of their ability to enhance light–matter interactions in a very confined volume. Examples of such devices include mechanical transducers, magnetometers, single-particle absorption spectrometers3, and microcavity sensors for sizing single particles and detecting nanometre-scale objects such as single nanoparticles and atomic ions. Traditionally, a very small perturbation near an optical microcavity introduces either a change in the linewidth or a frequency shift or splitting of a resonance that is proportional to the strength of the perturbation. Here we demonstrate an alternative sensing scheme, by which the sensitivity of microcavities can be enhanced when operated at non-Hermitian spectral degeneracies known as exceptional points. In our experiments, we use two nanoscale scatterers to tune a whispering-gallery-mode micro-toroid cavity, in which light propagates along a concave surface by continuous total internal reflection, in a precise and controlled manner to exceptional points. A target nanoscale object that subsequently enters the evanescent field of the cavity perturbs the system from its exceptional point, leading to frequency splitting. Owing to the complex-square-root topology near an exceptional point, this frequency splitting scales as the square root of the perturbation strength and is therefore larger (for sufficiently small perturbations) than the splitting observed in traditional non-exceptional-point sensing schemes. Our demonstration of exceptional-point-enhanced sensitivity paves the way for sensors with unprecedented sensitivity.2. Hossein Hodaei et al. Enhanced sensitivity at higher-order exceptional points, Nature (2017). DOI: 10.1038/nature23280AbstractNon-Hermitian degeneracies, also known as exceptional points, have recently emerged as a new way to engineer the response of open physical systems, that is, those that interact with the environment. They correspond to points in parameter space at which the eigenvalues of the underlying system and the corresponding eigenvectors simultaneously coalesce1, 2, 3. In optics, the abrupt nature of the phase transitions that are encountered around exceptional points has been shown to lead to many intriguing phenomena, such as loss-induced transparency4, unidirectional invisibility5, 6, band merging7, 8, topological chirality9, 10 and laser mode selectivity11, 12. Recently, it has been shown that the bifurcation properties of second-order non-Hermitian degeneracies can provide a means of enhancing the sensitivity (frequency shifts) of resonant optical structures to external perturbations13. Of particular interest is the use of even higher-order exceptional points (greater than second order), which in principle could further amplify the effect of perturbations, leading to even greater sensitivity. Although a growing number of theoretical studies have been devoted to such higher-order degeneracies14, 15, 16, their experimental demonstration in the optical domain has so far remained elusive. Here we report the observation of higher-order exceptional points in a coupled cavity arrangement—specifically, a ternary, parity–time-symmetric photonic laser molecule—with a carefully tailored gain–loss distribution. We study the system in the spectral domain and find that the frequency response associated with this system follows a cube-root dependence on induced perturbations in the refractive index. Our work paves the way for utilizing non-Hermitian degeneracies in fields including photonics, optomechanics10, microwaves9 and atomic physics17, 18. Explore furtherlast_img read more

In love with the desert skies

first_imgThe exhibition Rajasthan – Under the Desert Sky and the coffee book Looking Beyond the Surface are initiatives by photographer Rajesh Bedi, all set to be revealed in the Capital. The photo exhibition and book are unique in their approach as they reveal Rajasthan and its secrets in a manner unmatched by any previous attempt at documenting this beautiful region.Salman Khurshid, Minister of External Affairs and Jaswant Singh, Member of Parliament (Lok Sabha) will be the guest of honor for the event and Maharaja Gaj Singh II of Marwar-Jodhpur will inaugurate the exhibition.  Also Read – ‘Playing Jojo was emotionally exhausting’For most visitors Rajasthan is a state that represents grandeur and intoxicating royalty. But the photographer’s quest was to look beyond the customary splendour of Rajasthan. Using hot air balloons, microlite and cameras mounted on high-flying kites, he has experimented with photography to present the vastnesses of Rajasthan from a fresh perspective.  The outstanding aerial landscapes that have resulted complement the ground-level photographs.This work has been a labour of love spread over several years. Having spent weeks in the company of desert and tribal communities, accompanying them as they graze their flocks and travel to the spectacular fairs and religious occasions to capture the vibrant character of its people.  Also Read – Leslie doing new comedy special with NetflixThe lensman has climbed into the high fastnesses of the Aravallis, to discover deserted forts and primitive rock shelters that are inhabited to this day. The symmetry and ornate splendour of ancient step wells and mandana paintings by women folk have mesmerized him. For him the lines and shapes also have a powerful visual rhythm. From his large collection of photographs only 47 blowups on canvas will be on display at the exhibition.As a wildlife photographer, he has tried to capture rare glimpses of Rajasthan’s wildlife and gained moving insights into the communities that protect wild animals as an article of faith. Perhaps most rare in a sense of universal motherhood is the image of Kiran Bishnoi of Jodhpur district offering suckle to the young chinkara gazelle and her own son in chorus; a unique example in the world of harmony between  man and nature. This picture forms the back cover of the coffee table book, Rajasthan, Under the Desert Sky, published by Roli Books. The book has 100 images and text by Gillian Wright.  Kiran Bishnoi has consented to be present at the opening of Exhibition and would be happy to share her experience in raising the chinkara fawn and also about the values of conservation practiced by Bishnoi community.  Rajesh Bedi is one of India’s best-known freelance photographers on the international scene. He has travelled extensively to get freeze frames in shimmering heat and shifting dunes across the desert state of Rajasthan. The book Rajasthan: Under the Desert Sky is a labour of love, born of his desire to reveal Rajasthan and her secrets in a manner unmatched by any previous attempt at documenting this beautiful region.His photographs have been published in leading international magazines, such as National Geographic, Life, Geo, and Audubon Society Book, in various encyclopaedias and also been adopted on Indian Postage stamps. His published works include pictorial books on Banaras, Ladakh, Sikkim, and Sadhus – The Holy Men.His recent book Sadhu – The Seekers of Salvation is a monumental photographic study of the esoteric monastic orders. It offers in great detail the very first glimpse of women sadhavies and practicing Aghori ascetics, the most rarely seen of all the Indian sanyasis and sadhus.Also regarded as a leading photographer on wildlife in India, his large-format  pictorial book titled India’s Wild Wonders was one of the first wildlife books on India’s rich  fauna. He was adjudged Wildlife Photographer of the year 1986 in a worldwide competition. WHERE: Visual Arts Gallery, India Habitat CentreWHEN: 8 – 13 August,  10 am to 8 pmlast_img read more

Capital celebrations draw to an end

first_imgDelhi – a city which is all encompassing, modern and forward looking. A ‘mini-India’, the national capital is a melting pot for people from all parts of country who bring to it their diverse religious and cultural beliefs that enrich and augment Delhi’s all encompassing spirit.Concluding the Delhi Carnival on its third day organised with a view to celebrate the ‘Spirit of Delhi’, the organisers today hailed the tremendous public response and promised to come up with similar cultural ceremonies in the future. Also Read – ‘Playing Jojo was emotionally exhausting’In a unique and special initiative to celebrate this spirit of the Capital city, a three-day folk festival presented by Delhi Government’s Department of Art, Culture and Languages and the Sahitya Kala Parishad  that kicked off on Friday, concluded today. Inaugurated by Sheila Dikshit on Friday, the Delhi Carnival was being showcased in such a manner that it brings forth the rich cultural heritage of India to the people.  A 64/40 feet multi-level stage, 250 performers from across India and two special songs by noted singer Palash Sen and Euphoria  – added to the grandeur of the mega event. Also Read – Leslie doing new comedy special with NetflixThe festival which for the first time took place at the East Delhi-situated Yamuna Sports Complex was a specially choreographed presentation of the folk music and dances from various parts of India.“This mega event presented the best of Indian people’s art to Delhi’s audiences for the first time in such a big way. We are very happy with the terrific response we received on all three days. We wholeheartedly thank the people of Delhi who came here in large numbers and the Delhi government for their active support. The festival was in one way a celebration of the ‘Spirit of Delhi’ that is a microscopic representation of India. The specially created songs by Palash Sen added to the glory of the event,’ said eminent theatre personality Bhanu Bharti, who also was the program director. ‘250 performers from across the country- from Assam, Tripura, Manipur, Madhya Pradesh, Rajasthan, Andhra Pradesh and others,  had put their best in an attempt to enthrall the Delhi audience through this endeavor that celebrated cultural diversity and the richness it brings to a civilization,’ Bharti added.The performances on three days which lasted for an hour and a half began at 7 pm during which people got to experience the multiple folk art forms of the country.’Folk music and folk art depicts the richness of your culture and it is very important to keep your folk arts alive and thriving. Delhi is a city that loves culture and absorbs everything that comes its way. The people of Delhi, I hope have loved this event and every next day, the crowd exceeded the previous day I sincerely feel, this will stay with them for a long time,’ said SS Yadav, Secretary, Department of Art, Culture and Languages.last_img read more

Relief at last Modi gives Rs 1000cr to Hudhudhit Andhra

first_img‘The central government is with Andhra Pradesh government in this hour of crisis,’ said Modi who reviewed the damage done by the cyclone on Tuesday. PM arrived in Visakhapatnam on Tuesday afternoon to visit cyclone-hit area and other parts of north coastal Andhra.Soon after landing at Visakhapatnam airport, he inspected the facility extensively damaged by cyclonic storm Hudhud on Sunday. Officials briefed him about the damages. Andhra Pradesh governor ESL Narasimhan, chief minister N Chandrababu Naidu, central government ministers M Venkaiah Naidu and Ashok Gajapati Raju received him at the airport. Also Read – Need to understand why law graduate’s natural choice is not legal profession: CJIPeople in the cyclone-ravaged town of Visakhapatnam continue to live without electricity and communication facilities for the third day in the row since Sunday. The scarcity of drinking water, milk and other essential commodities have added to the woes of this port town.Two days after the severe cyclonic storm Hudhud battered the coastline, the city of 18 lakh people remained in darkness and mostly deprived of potable water. Piped potable water supplies have run out, too. Motor pumps installed in homes and apartments aren’t running, with power supply yet to be restored. Also Read – Health remains key challenge in India’s development: KovindThe authorities haven’t been able to supply water in tankers either, the citizens complained. Cashing in on the situation are greedy retailers, selling 20 litre water bottles for Rs 300 each. Women carrying children too are running around to buy milk, some of them standing in long queues. In some areas, half-litre packets of milk were sold at Rs 50 each, which is twice their actual price. Mobile phones remain dead here for the third day in a row, with telecom services yet to be restored. ATM machines aren’t working either.last_img read more

Build shelter homes or face consequences SC to states

first_imgSending a stern warning to state governments, a bench headed by Chief Justice HL Dattu said the states will have to face consequences if they fail to put shelter homes before the onset of winter.‘We will be very harsh to you if the shelter homes are not ready,’ the bench said.The bench was hearing a PIL filed by advocate E R Kumar alleging seeking its direction to governments to build shelter homes as many homeless people die due to cold in winter. Also Read – Need to understand why law graduate’s natural choice is not legal profession: CJIThe bench said that it will send court commissioners to find out whether the governments have set up night shelters or not.The apex court had earlier passed a series of orders for providing shelter to homeless people saying that right to shelter is a fundamental right.‘Nothing is more important for the State than to preserve and protect the lives of the most vulnerable, weak, poor and helpless people. The homeless people are constantly exposed to the risk of life while living on the pavements and the streets and the threat to life is particularly imminent in the severe and biting cold winter, especially in the northern India,’ the apex court had said.last_img read more

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