Analogy of cochlea as resonator could lead to artificial copies

first_imgThis image shows the cochlea of a rabbit, which is very similar to that of most mammals, including humans. The three rows of outer hair cells could act like electrodes on a SAW resonator. Image Credit: Andrew Bell (originally from Counter, et al.). 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 squirting waves and the SAW configuration, the cochlea could theoretically provide sharp resonance frequencies typical of the human ear, in the range of 20 to 20,000 Hz.“The idea is that cells are not lonely, independent entities unaware of other cells,” said Bell. “Instead, cells appear in populations and cooperatively interact so as to perform signal processing. We have long known that nerve cells process information via a network of interactions (neural nets), but here we see a preneural example: outer hair cells act both to detect sound and pass it on to neighboring cells, which do the same. Shuttling of signals back and forth leads to positive feedback and frequency analysis, and this might prompt us to look for similar interactions among other sensing cells. Visual, olfactory, and balance cells, for example, could well work in similar ways.”Bell speculates that the main reason past artificial cochleas fell short is that their designers focused on the passive traveling wave picture. But building a cochlea based on the active processes residing in the resonator analogy may, Bell thinks, open up a much more effective way forward.“A SAW-like cochlea would form a rugged spectral analyzer—a reasoning behind existing artificial cochleas—but it could be much more sensitive then existing prototypes,” said Bell.Bell explained that more experiments and testing will determine if this idea is accurate. He also added that there may be some exciting characteristics of the ear to discover.“Future research needs to be directed to validating the SAW resonator model,” he said. “But then there are finer features which call for explanation, too. What is the purpose of the ‘V’ shape of the stereocilia, for example? There is reason to think it could relate to detecting musical ratios in sounds, and if so this would give a marvelous physical underpinning to our remarkable musical sense. The cochlea may be highly tuned—and musical.”Citation: Bell, Andrew. “Sensors, motors, and tuning in the cochlea: interacting cells could form a surface acoustic wave resonator.” Bioinspiration and Biomimetics 1 (2006) 96-101.By Lisa Zyga, Copyright 2006 All rights reserved. This material may not be published, broadcast, rewritten or redistributed in whole or part without the express written permission of A SAW resonator (top) has two sets of electrodes that generate and detect electromechanical ripples. With a similar structure, the cochlea (bottom) could use outer hair cells to sense and create standing waves. Image Credit: Andrew Bell. In developing his new idea, Bell was inspired by a discovery in 1978 that most human ears continuously emit very pure, soft tones—sounds which can be picked up with a sensitive microphone. The current theory of a hydrodynamical traveling wave stimulating hair cell stereocilia does not easily accommodate such fine tuning, leading Bell to propose that the outer hair cells in the cochlea actively cooperate to amplify sound. “When you listen to a recording of the sound that the cochlea makes, you hear something like a carillon of wind chimes,” Bell told “It’s easy to get the impression that something seems to be resonating.”He considered a design where the cochlea would function like a SAW resonator, a device in solid-state electronics commonly used in cell phones due to its small size. SAW resonators use rows of electrodes to process signals by creating electromechanical waves between them whose wavelengths correspond to the spacing of the electrodes. Bell noted a striking characteristic of the outer hair cells: they always lie in three well-defined rows, much like the electrodes on a SAW resonator. Bell thinks that the waves align with the rows of hair cells, with the first and third rows being in antiphase with the middle row. Such SAW-like behavior would also correspond well with results from past experiments in auditory science.Further, like a SAW resonator, the cochlear amplifier would operate in a feedback circuit mediated by the waves. Because the hair cells are linked to soft structures such as the gelatinous tectorial membrane, feedback in the cochlea would require a slow-moving wave, one with a very short wavelength. Recently, a prime candidate for such a wave has been identified: called “squirting waves,” these waves arise in fluids constrained in ways similar to those found in the cochlea. center_img In attempting to construct an artificial cochlea—and faced with limited knowledge of how the living chamber works—scientists might need to look no further than a simple electronic device: a surface acoustic wave (SAW) resonator. Recently, scientist Andrew Bell suggested that the cochlea exhibits similar structure and electromechanical properties to this common piece of circuitry. Citation: Analogy of cochlea as resonator could lead to artificial copies (2007, January 9) retrieved 18 August 2019 from The cochlea—a spiral-shaped, hollow bone in the inner ear—plays a vital role in sensing, processing, and amplifying sounds. The common understanding of the workings of the cochlea centers on its passive behavior, in which tiny hair cells create electrical signals from vibrations in the surrounding fluid.last_img read more

Spinning Orbita Mouse Available in January

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. Explore further It looks like a large shiny button, but the round object is actually the world’s first wireless three-axis mouse, according to its designers, an Australian technology company called Cyber Sport. The company designed the Orbita mouse to overcome some of the limitations of conventional mice by replacing the conventional scroll wheel with a 360° spinning “jog wheel.” An oracle for object-oriented programmers Citation: Spinning ‘Orbita’ Mouse Available in January (2008, December 15) retrieved 18 August 2019 from Cyber Sport’s Orbita mouse replaces the scroll wheel with a spinning jog wheel for more intuitive navigation. Image credit: Cyber Sport. Cyber Sport says that the new mouse provides a more intuitive control center, better ergonomic handling, and higher efficiency. Rather than scrolling down a page with jerky vertical finger movement, users of the Orbita mouse can navigate by rotating the mouse left or right in a natural dialing motion.The Orbita mouse has a small white button at the top, which serves as the orientation button. Pressing that button calibrates the mouse in the same direction as the arrow on the screen is currently pointing, so that left, right, up, and down navigating directions are based on that orientation. The orientation feature is particularly useful for navigating in 3D gaming environments, Google Earth maps, and 3D CAD designs. The mouse could also have advantages in audio and video applications for frame-by-frame manipulation. Because the mouse can be used at any angle, the buttons can also be used at any angle. The mouse has one “push” button and a series of “squeeze” buttons to serve as a “right click.”A third button, the “jog dimple” button, can be used to either spin the mouse or it can work like a standard scroll wheel button on a conventional mouse. By pressing this button, users can also switch between vertical and horizontal scrolling. Besides rotating the mouse with a finger, the device is sensitive enough that users can flick it to make it spin freely and continuously. The Orbita mouse, which works with both Macs and PCs, will be sold for $98.50 starting in January 2009. More information:” alt=”last_img” /> read more

The optomechanical Kerker effect Controlling light with vibrating nanoparticles

first_img © 2019 Science X Network Credit: Poshakinskiy & Poddubny. “Even though the light scattering has been understood for more than a century after the works of Rayleigh, Raman, Landsberg and Mandelstam, it remains both a fundamental and applied challenge to route light scattered at the nanoscale in the direction at will,” Alexander Poshakinskiy, one of the researchers who carried out the study, told “The ability to control the direction, frequency and polarization of the scattered light is essential for operation of optical circuits.”Devices that can control the direction of scattered light could have numerous useful applications, particularly for the operation of antennas and routing of light. In the 1980s, researchers theorized that a directional scattering of light can be achieved via the so-called Kerker effect. This effect essentially exploits the interference of electric and magnetic dipole emission patterns, which have different spatial parity, yielding the suppression of forward or backward scattering when they are superposed. “Realization of the conventional Kerker effect requires the particles to have electric and magnetic polarizabilities of the same strength,” Poshakinskiy said. “However, this is challenging because magnetic response at optical frequencies is extremely weak. A possible workaround is to use large submicron-size nanoparticles hosting both electric and magnetic Mie resonances. However, optical Kerker effect for the particles smaller than the wavelength in the medium is still unfeasible. In our work, we show that even small particles, that lack magnetic response when at rest, do acquire it when they start trembling in space, enabling realization of what we call optomechanical Kerker effect.”In the optomechanical Kerker effect, proposed by Poshakinskiy and his colleague Alexander Poddubny, the tunable directional scattering of light is attained for a particle that lacks magnetic resonances as it trembles in space. The trembling motion of the electric dipole in space leads to the appearance of a magnetic dipole, as one could expect from the Lorentz transformation. 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: A. V. Poshakinskiy et al. Optomechanical Kerker Effect, Physical Review X (2019). DOI: 10.1103/PhysRevX.9.011008 Journal information: Physical Review X Explore further Citation: The optomechanical Kerker effect: Controlling light with vibrating nanoparticles (2019, March 6) retrieved 18 August 2019 from For the Kerker effect to occur, particles need to have electric and magnetic polarizabilities of the same strength. This, however, is very challenging to achieve, as magnetic optical resonances in small particles are relatively weak. Researchers at Ioffe Institute, in St. Petersburg, have recently shown that a similar effect can be attained when small particles are trembling in space. Tiny particles with varied shapes scatter light in useful and unusual ways “We show that magnetic and electric dipole induced in the trembling particle by incident light counterintuitively are of the same order when inelastic scattering is considered,” Poshakinskiy explained. “The phase difference between the electric and magnetic dipoles is governed by the frequency dependence of the particle permittivity. For a resonant particle, this enables control of the scattering direction via the detuning of light frequency from the resonance: The light is scattered preferably forward at resonance and backward away from it. ” The researchers show that in the optomechanical Kerker effect, the figure of merit that quantifies how much of the light is scattered in a particular direction compared to all other directions (i.e. directivity), can be as high as 5.25. This exceeds the directivity of 3 attained in the classical Kerker effect, due to the additional electric quadrupole momentum induced by the mechanical motion. In their study, Poshakinskiy and Poddubny also introduced a second effect, which they refer to as ‘the optomechanical spin-Hall effect.’ In this effect, a directional inelastic scattering of light, depending on its circular polarization, is realized for a small trembling particle.”The optomechanical spin-Hall effect can be achieved when a particle vibrates around a circular trajectory rather that a straight line,” Poshakinskiy said. “We show that the angular mechanical momentum of the particle can be transferred to the spin of light. Then the electromagnetic waves scattered by the trembling particle to the left and to the right attain opposite circular polarization.” The findings gathered by Poshakinskiy and Poddubny suggest that the interaction between light and mechanical motion has an intrinsically multipolar nature. This quality could be exploited in a variety of systems, ranging from cold atoms to two-dimensional materials and superconducting qubits. “We believe that the proposed optomechanical Kerker opens a new multidisciplinary field by uncovering, for the first time, to our knowledge, a highly untrivial link between optomechanics and nanophotonics,” Poshakinskiy said. “From a practical point of view, the proposed effects can be used to design non-reciprocal nanoscale optical devices.”Optical non-reciprocity, meaning that light is transmitted forward and backward through an optical circuit differently, is crucial for optical signal processing. Most existing non-reciprocal optomechanical devices are based on optical resonators, which limit their minimal size to sub-microns. The results collected by Poshakinskiy and Poddubny show that tunable optomechanical non-reciprocity can also occur at nanoscale when using small trembling particles with resonant polarizability. “Optical non-reciprocity is also a key ingredient for the design of photonic topological circuits,” Poshakinskiy added. “In an array of trembling particles, one can expect a disorder-robust propagation of light and sound, ensured by the time modulation of optical and mechanical properties.”The study carried out by Poshakinskiy and Poddubny shows how the tunable directional scattering of light can be achieved at nanoscale, introducing the optomechanical Kerker and spin-Hall effects. In the future, their findings could have several interesting applications, for instance, informing the design of non-reciprocal topological circuits. The researchers are now planning to demonstrate the optomechanical Kerker effect in lab experiments. “The proof of concept would be observation of the directional backscattering by trembling objects, which can be realized even away from material resonances,” Poshakinskiy said “We believe that this can be done in a variety of systems e.g., semiconductor quantum dots, transitional metal dichalcogenides or graphene. However, the key feature of the optomechanical Kerker effect is the possibility to switch the direction of scattering between forward and backward. This requires particles with extremely sharp resonances in their electromagnetic response. Our estimations show that such switching can be realized for cold atoms in optical traps or superconducting qubits in radio-frequency circuits.”last_img read more

Capital gets a Mahatma Calling

first_imgOne of the best known theatre directors of India Bhanu Bharti, is bringing for the people of Delhi a story of Bapu’s last days, performed in a one actor play by actor Sunit Tandon. The play is all set to hit the proscenium this monthBapu – A Saga of Truth, compassion and non-violence is being presented by the Aaj Theatre Company. The play depicts Bapu’s indomitable courage and will power to surmount all adversities but even he who baffled a mighty empire through his dedication to non-violence, was a helpless man in his last days.  Also Read – ‘Playing Jojo was emotionally exhausting’The play which has earlier been performed in Hindi, is being played out in English for the first time. Audience will get to reflect and contemplate on the history of partition as the director tries to re-explore what went on inside the great mind at that point of time.’If we talk about humanity, violence has been our constant companion. Even today it is, and this is the reason why Bapu will always remain relevant. Our play unfolds against the backdrop of the tragedy of 1947, the partition of the subcontinent and the violence that accompanied it. It is in this backdrop that we observe the helpless personality of the man who worked so hard to ensure that the Indian independence was a bloodless revolution,’said Bhanu Bharti.Bharti ,revered by Delhi for his path-breaking presentations of Andha Yug and Tughlaq, is set to present the story of the inner turmoil of Mahatma Gandhi with his intrinsic directorial finesse.last_img read more

Of progressive sciences

first_imgDoordarshan’s new series A Question Of Science will fulfill viewers scientific curiosity and the chase for answers in a 26 part series on the most exciting and cutting-edge research and innovation happening across India’s science labs and technology hubs.Each 22-24 minute episode introduces viewers to a team of researchers, working to solve a pressing problem of science. Doordarshan traverse a wide range of fields – from genetics to particle physics, from wildlife conservation to radio-astronomy, from biomedical engineering to agricultural innovation – every aspect of India’s scientific landscape will be explored. Also Read – ‘Playing Jojo was emotionally exhausting’This quest took A Question Of Science across the length and breadth of India and beyond (including CERN at Geneva). In each story, viewers will meet the researchers and understand the basic questions they are trying to answer. Using simple scientific explanations, analogies and state-of-the-art 2D/3D animation to bring the science alive. The show will also delve into how science is ‘done’ – the ups and downs, the challenges, triumphs and failures of scientific pursuit. Also Read – Leslie doing new comedy special with NetflixAn episode on particle physics will show India’s contribution to the experiments at the Large Hadron Collider, the India-based neutrino observatory. Also a wildlife conservation episode will show underwater acoustics in conservation of Gangetic river dolphin, technologies at LaCones, conservation of Olive Ridley turtles and more.Stem cell innovation in restoring corneal sight, artificial heart pumps and heart valves, sleep research, brain bank will be highlighted in an episode of medicine and biomedical engineering.Another show on agriculture will talk about improved strains of high-yield rice using DNA marker technology, apomixis in seed production An array of topics like astronomy and space, industrial innovation, new-Age energy, stratospheric balloon technology, DNA Fingerprinting, insect Flight will also be covered.When: Every Wednesday, 9 amlast_img read more

Playing for summer

first_imgAn artiste knows no seasonal bounds! There is no heat, no chill that can overwhelm an artistic heart. As people of the capital look for summer retreats and ways to beat the heat, we remind you about the large group of artistes who are to present a mega theatrical extravaganza The Summer Theatre Festival next week for Delhiites reeling under the hot weather. From the story of a family broken by the devastating Indian partition to an adaptation of Shakespearse’s classic Merchant of Venice to an adult comedy satiring Indian men, three widely different and interesting plays will be staged over three days. Also Read – ‘Playing Jojo was emotionally exhausting’The three grand productions are full of emotions and liveliness, are supported effectively by Indian music and have a rich content that will both entertain you and touch you deep inside. The USP of this festival is the variety it is offering. While Couple Trouble is an adult comedy which subtly underlines the double standards of married men, Saudagar has been adapted from Shakespeare’s Merchant of Venice in an Indian set-up. The last play of the festival, Wo Lahore, will introduce to you to a small blissful family living in Lahore which is eventually destroyed as a consequence of India’s partition.When: 20 – 22 June Where: Shri Ram Centre Timing: 7 pmlast_img read more

CM to meet Delhi farmers

first_imgDelhi Chief Minister Arvind Kejriwal will meet farmers of the national Capital in the wake of unseasonal rains, which have damaged the standing crops in North India. Besides, Kejriwal is likely to lay out his government’s roadmap for the dwellers of the unauthorised colonies in the capital, government sources said. “The Chief Minister will address the Sahyog Rally in Mundka on Saturday. He would listen to their problems especially of those whose crops have been damaged by rain,” he said. The rally will be held at Mundka in north west Delhi where a sizeable number of farmers live. “Kejriwal will also share with those living in unauthorised colonies his government’s plans for them,” an official said, adding that he will meet them and listen to their problems on Sunday.last_img read more

Showcasing the Islamic heritage of Assam

first_imgThe Indira Gandhi National Centre for the Arts (IGNCA) Film Circle screens two films a month on the second and fourth Friday. This Friday, Islamic Heritage of Assam directed by Abdul Majid will be screened. The documentary deals with some of the key factors and aspects of Islamic heritage in Assam, such as, the formation of the Muslim community, invasions and post invasion settlements and migrations during the time of Ahom kings from Shuhungmung (1497-1539) to Rudra Singha (1696-1714). Also Read – ‘Playing Jojo was emotionally exhausting’Islamic Heritage of Assam looks at the life-cycle events of Sufi saints, Islamic institutions, creative heritage, folk songs and creative traditions in Assam. It shows that Islamic heritage in Assam has been shaped over eight centuries since the first footing of the Muslims in this part of the country through interface and interaction of the community with the local non-Muslims.The liberal Vaishnava tradition in healthy conjunction with the Sufi tradition offered unique opportunities to the Muslims to identify and integrate themselves into local lifestyles and build a harmonious customary and liberal Islamic heritage. The film has been produced under the Confluence of Tradition and Composite Cultures program of the Janapada Sampada Division of the IGNCA.last_img read more

Now Puja committees to get online police permission

first_imgKolkata: In a major step to streamline the process of giving permission to the puja committees, Bidhannagar Police has decided to give it online.A high-level meeting to discuss the matter was held on Wednesday. Sabyasachi Dutta, mayor of Bidhannagar Municipal Corporation (BMC), Krishna Chakraborty, chairperson of BMC and Sujit Basu, MLA Bidhannagar attended the meeting along with Debashis Sen, chairman of Housing Infrastructure Development Corporation ( HIDCO). Also Read – Rain batters Kolkata, cripples normal lifeThe representatives of Salt Lake, Lake Town and Sribhumi attended the meeting. Earlier, the puja organisers had to obtain permission from the Fire and Emergency department and local civic body and then apply for police permission. The process was elaborate and the organizers often complained of harassment. To put an end to the harassment of the organizers, they can now apply for police permission online after getting the required clearance. It is a major development and will reduce the time of giving permission. The authorities of HIDCO will sit with the puja committees at New Town on Thursday. HIDCO has decided to select the best Puja through Blockchain to ensure fair competition.last_img read more