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Sample records for electromagnetic fluctuation induced

  1. Experimental investigation of impulsive magnetic reconnection induced by large amplitude electromagnetic fluctuations in the presence of a guide field

    NASA Astrophysics Data System (ADS)

    Kuwahata, Akihiro; Inomoto, Michiaki; Yanai, Ryoma; Ono, Yasushi

    2015-11-01

    Impulsive enhancement of magnetic reconnection is one of the potential candidates to invoke various explosive events observed in nature and laboratory plasmas. In TS-3 laboratory experiment with a guide field of Bguide /Brec = 1-2.5, impulsive growth of the reconnection electric field was observed just behind the onset of large-amplitude electromagnetic fluctuations (f = 1.5-2 fci and the amplitude was 0.1Brec). It was found that both the fluctuation amplitude and the enhanced reconnection electric field during the fluctuation period showed positive correlation with the guide field. The normalized reconnection rate of about 0.03 before the onset of fluctuations was reasonably comparable with the classical reconnection rate of Sweet-Parker model. However, the reconnection rate rose up to 0.11 after the fluctuations onset, suggesting that the transition from slow steady reconnection to fast impulsive reconnection took place. Since the fluctuation amplitude was so large that the nonlinear terms of the induced electric field was not negligible. The electric field enhancement due to the nonlinear contribution from the observed fluctuation was 650 V/m, which showed good agreement with the experimentally observed electric field increment of about 800 V/m.

  2. Theory of electromagnetic fluctuations for magnetized multi-species plasmas

    SciTech Connect

    Navarro, Roberto E. Muñoz, Víctor; Araneda, Jaime; Moya, Pablo S.; Viñas, Adolfo F.; Valdivia, Juan A.

    2014-09-15

    Analysis of electromagnetic fluctuations in plasma provides relevant information about the plasma state and its macroscopic properties. In particular, the solar wind persistently sustains a small but detectable level of magnetic fluctuation power even near thermal equilibrium. These fluctuations may be related to spontaneous electromagnetic fluctuations arising from the discreteness of charged particles. Here, we derive general expressions for the plasma fluctuations in a multi-species plasma following arbitrary distribution functions. This formalism, which generalizes and includes previous works on the subject, is then applied to the generation of electromagnetic fluctuations propagating along a background magnetic field in a plasma of two proton populations described by drifting bi-Maxwellians.

  3. Electromagnetic fluctuations and normal modes of a drifting relativistic plasma

    SciTech Connect

    Ruyer, C.; Gremillet, L.; Bénisti, D.; Bonnaud, G.

    2013-11-15

    We present an exact calculation of the power spectrum of the electromagnetic fluctuations in a relativistic equilibrium plasma described by Maxwell-Jüttner distribution functions. We consider the cases of wave vectors parallel or normal to the plasma mean velocity. The relative contributions of the subluminal and supraluminal fluctuations are evaluated. Analytical expressions of the spatial fluctuation spectra are derived in each case. These theoretical results are compared to particle-in-cell simulations, showing a good reproduction of the subluminal fluctuation spectra.

  4. Electromagnetically Induced Entanglement.

    PubMed

    Yang, Xihua; Xiao, Min

    2015-08-28

    Quantum entanglement provides an essential resource for quantum computation, quantum communication, and quantum network. How to conveniently and efficiently produce entanglement between bright light beams presents a challenging task to build realistic quantum information processing networks. Here, we present an efficient and convenient way to realize a novel quantum phenomenon, named electromagnetically induced entanglement, in the conventional Λ-type three-level atomic system driven by a strong pump field and a relatively weak probe field. Nearly perfect entanglement between the two fields can be achieved with a low coherence decay rate between the two lower levels, high pump-field intensity, and large optical depth of the atomic ensemble. The physical origin is quantum coherence between the lower doublet produced by the pump and probe fields, similar to the well-known electromagnetically induced transparency. This method would greatly facilitate the generation of nondegenerate narrow-band continuous-variable entanglement between bright light beams by using only coherent laser fields, and may find potential and broad applications in realistic quantum information processing.

  5. Multiphoton electromagnetically induced transparency

    NASA Astrophysics Data System (ADS)

    Wen, Lingling; Kang, Hoonsoo; Zhu, Yifu; Wu, Ying

    2003-05-01

    We show that in multi-level atomic systems coupled by multiple laser fields, all linear and nonlinear absorptions may be completely suppressed, leading to the multiphoton electromagnetically induced transparency (EIT). Under suitable conditions, multiphoton EIT may be used to realize selective steady-state population inversion in coherently pumped atomic systems and achieve efficient nonlinear light generation at low light intensities. As examples, we will present studies of multiphoton EIT in five-level and six-level atomic systems, which demonstrate steady-state population inversion from selective nonlinear excitation. We will also present studies of resonant hyper-Raman and four-wave mixing processes that are enhanced via suppression of the lower-order linear and nonlinear absorptions, and are capable of generating short-wavelength, coherent light at low pump intensities.

  6. Electromagnetic interactions between fluctuations near the superconducting phase transition

    SciTech Connect

    Goldenfeld, N.; Pethick, C.J.

    1989-05-01

    We calculate the amplitude ratio C/sub +//C/sub -/ for specific-heat fluctuations near the superconducting-phase transition, taking into account the lowest-order fluctuations about mean-field theory. For a U(1) Ginzburg-Landau theory, minimally coupled to electromagnetism in d dimensions, C/sub +//C/sub -/ = 2/(2/sup d/2/+kappa/sup -d/), where kappa is the Ginzburg-Landau parameter. We discuss how this result arises from the microscopic theory of superconductivity.

  7. Quasilinear theory of general electromagnetic fluctuations in unmagnetized plasmas

    SciTech Connect

    Schlickeiser, R. E-mail: yoonp@umd.edu; Yoon, P. H. E-mail: yoonp@umd.edu

    2014-09-15

    The general quasilinear Fokker-Planck kinetic equation for the plasma particle distribution functions in unmagnetized plasmas is derived, making no restrictions on the frequency of the electromagnetic fluctuations. The derived kinetic particle equation complements our earlier study of the general fluctuation's kinetic equation. For collective plasma eigenmodes and gyrotropic particle distribution functions, the two coupled kinetic equations describe the self-consistent dynamical evolution of the plasma. The limit of weakly damped collective modes correctly reproduces the well-known textbook kinetic particle equation with longitudinal Langmuir and ion-acoustic fluctuations, demonstrating, in particular, the resonant nature of parallel momentum diffusion of particles. In the limit of aperiodic modes, the Fokker-Planck equation contains the nonresonant diffusion of particles in momentum and the parallel and perpendicular momentum drag coefficients. As an application these drag and diffusion coefficients are calculated for extragalactic cosmic ray particles propagating in the unmagnetized intergalactic medium. Whereas for all cosmic rays, the perpendicular momentum diffusion in intergalactic aperiodic fluctuations is negligibly small; cosmic ray protons with energies below 10{sup 5 }GeV are affected by the plasma drag.

  8. Dipole-Induced Electromagnetic Transparency

    NASA Astrophysics Data System (ADS)

    Puthumpally-Joseph, Raiju; Sukharev, Maxim; Atabek, Osman; Charron, Eric

    2014-10-01

    We determine the optical response of a thin and dense layer of interacting quantum emitters. We show that, in such a dense system, the Lorentz redshift and the associated interaction broadening can be used to control the transmission and reflection spectra. In the presence of overlapping resonances, a dipole-induced electromagnetic transparency (DIET) regime, similar to electromagnetically induced transparency (EIT), may be achieved. DIET relies on destructive interference between the electromagnetic waves emitted by quantum emitters. Carefully tuning material parameters allows us to achieve narrow transmission windows in, otherwise, completely opaque media. We analyze in detail this coherent and collective effect using a generalized Lorentz model and show how it can be controlled. Several potential applications of the phenomenon, such as slow light, are proposed.

  9. Electron diffusion in tokamaks due to electromagnetic fluctuations

    SciTech Connect

    Horton, W.; Choi, D.I.; Yushmanov, P.N.; Parail, V.V.

    1986-05-01

    Calculations for the stochastic diffusion of electrons in tokamaks due to a spectrum of electromagnetic drift fluctuations are presented. The parametric dependence of the diffusion coefficient on the amplitude and phase velocity of the spectrum, and the bounce frequency for the electrons is studied. The wavenumber spectrum is taken to be a low order (5 x 5) randomly-phased, isotropic, Monotonic spectrum extending from k /sub perpendicular min/ approx. = ..omega../sub ci//c/sub s/ to k/sub perpendicular max/ approx. = 3..omega../sub pe//c with different power laws of decrease phi k approx. = phi 1/k/sup m/, 1 less than or equal to m less than or equal to 3. A nonlinear Ohm's law is derived for the self-consistent relation between the electrostatic and parallel vector potentials. The parallel structure of the fluctuations is taken to be such that k parallel/sup nl/upsilon/sub e/ < w/sub k/ due to the nonlinear perpendicular motion of the electrons described in the nonlinear Ohm's law. The diffusion coefficient scales approximately as the neo-Alcator and Merezhkin-Mukhovatoc empirical formulas for plasma densities above a critical density.

  10. Mechanical temporal fluctuation induced distance and force systematic errors in Casimir force experiments

    NASA Astrophysics Data System (ADS)

    Lamoreaux, Steve; Wong, Douglas

    2015-06-01

    The basic theory of temporal mechanical fluctuation induced systematic errors in Casimir force experiments is developed and applications of this theory to several experiments is reviewed. This class of systematic error enters in a manner similar to the usual surface roughness correction, but unlike the treatment of surface roughness for which an exact result requires an electromagnetic mode analysis, time dependent fluctuations can be treated exactly, assuming the fluctuation times are much longer than the zero point and thermal fluctuation correlation times of the electromagnetic field between the plates. An experimental method for measuring absolute distance with high bandwidth is also described and measurement data presented.

  11. Van Allen Probe Spacecraft Potential Fluctuations and Electromagnetic Waves: A Parameter Space Survey

    NASA Astrophysics Data System (ADS)

    Sturner, A. P.; Ergun, R.; Malaspina, D.

    2013-12-01

    The study of chorus waves, an important mechanism for the energization and loss of particles in the radiation belts and inner magnetosphere, has been significantly aided by observations of fluctuations in a spacecraft's potential, which have been shown to be correlated with plasma density structures. However, recent analysis of Van Allen Probe data suggests that the oscillatory electromagnetic fields of chorus waves may also induce spacecraft potential fluctuations via enhanced photoelectron escape, calling into question our understanding of chorus waves. We use a fully 3D particle tracing simulation to study the equilibrium potential of a model Van Allen Probe spacecraft under various plasma conditions, varying thermal temperature, electric and magnetic field strength, plasma density, etc., to better understand the parameter space under which enhanced photoelectron escape becomes important.

  12. Constraints on stable equilibria with fluctuation-induced (Casimir) forces.

    PubMed

    Rahi, Sahand Jamal; Kardar, Mehran; Emig, Thorsten

    2010-08-13

    We examine whether fluctuation-induced forces can lead to stable levitation. First, we analyze a collection of classical objects at finite temperature that contain fixed and mobile charges and show that any arrangement in space is unstable to small perturbations in position. This extends Earnshaw's theorem for electrostatics by including thermal fluctuations of internal charges. Quantum fluctuations of the electromagnetic field are responsible for Casimir or van der Waals interactions. Neglecting permeabilities, we find that any equilibrium position of items subject to such forces is also unstable if the permittivities of all objects are higher or lower than that of the enveloping medium, the former being the generic case for ordinary materials in vacuum. PMID:20868024

  13. Constraints on Stable Equilibria with Fluctuation-Induced (Casimir) Forces

    SciTech Connect

    Rahi, Sahand Jamal; Kardar, Mehran; Emig, Thorsten

    2010-08-13

    We examine whether fluctuation-induced forces can lead to stable levitation. First, we analyze a collection of classical objects at finite temperature that contain fixed and mobile charges and show that any arrangement in space is unstable to small perturbations in position. This extends Earnshaw's theorem for electrostatics by including thermal fluctuations of internal charges. Quantum fluctuations of the electromagnetic field are responsible for Casimir or van der Waals interactions. Neglecting permeabilities, we find that any equilibrium position of items subject to such forces is also unstable if the permittivities of all objects are higher or lower than that of the enveloping medium, the former being the generic case for ordinary materials in vacuum.

  14. Features of electromagnetic radiation time-and-frequency fluctuation intensity distributions from human brain structures.

    PubMed

    Kublanov, V S; Gasilov, V L; Kazakov, Y E

    2000-01-01

    Time-and-frequency fluctuation intensity distributions' analysis is made of the electromagnetic radiation obtained from deep human brain structures. The role of monitoring the distribution changes due to various cerebral circulation disorders is explained.

  15. Broadband cavity electromagnetically induced transparency

    SciTech Connect

    Wei Xiaogang; Wang Yanhua; Zhang Jiepeng; Zhu Yifu

    2011-10-15

    Cavity electromagnetically induced transparency (EIT) is created in a three-level atomic system confined in a cavity and coupled to a free-space control laser and is manifested as a narrow transmission peak of a probe laser coupled into the cavity mode and tuned to the two-photon Raman resonance with the control laser. Cavity EIT can be observed with a control laser detuned from the atomic transition frequency in a range limited by the vacuum Rabi splitting of two cavity-atom normal modes. This leads to the broadband cavity EIT obtained in the coupled-cavity-atom system with a free-space, broadband control laser. We report an experimental observation of broadband cavity EIT in cold Rb atoms with a frequency-modulated control laser and discuss its application in multichannel and multifrequency light memory.

  16. Electromagnetically induced transparency in rubidium

    NASA Astrophysics Data System (ADS)

    Olson, Abraham J.; Mayer, Shannon K.

    2009-02-01

    We investigate ladder-type electromagnetically induced transparency (EIT) in rubidium gas. The theoretical absorption profile of a weak probe laser beam at 780.2nm (5S1/2→5P3/2) is modeled in the presence of a strong coupling laser beam at 776.0nm (5P3/2→5D5/2) and the absorption transparency window is characterized. We use two grating-feedback diode lasers and observe EIT experimentally in rubidium and compare the results to the theory. This experiment brings quantum optics into the advanced undergraduate laboratory and utilizes equipment and expertise commonly available in laboratories equipped to perform diode-laser-based absorption spectroscopy of rubidium.

  17. On the fluctuation induced mass enhancement

    NASA Astrophysics Data System (ADS)

    Van Hoa, Nguyen; Tuan, Vu Ngoc; Van Xuan, Le; Lan, Nguyen Tri; Viet, Nguyen Ai

    2016-06-01

    The effective mass induced by the background fluctuation on particles is considered. The analytical results show that the effective mass depends only on the properties of fluctuation, and takes non-zero value when and only when fluctuation mean value is non-zero. The possible applications of the obtained results to complex systems such as biology and ecology where environmental factors lead to the changes of the information exchange ranges from long to short one are discussed, i.e. the possibility of using physical modeling techniques to investigate macroscopic behaviors of some complex systems under consideration.

  18. Poynting vector, energy densities, and pressure of collective transverse electromagnetic fluctuations in unmagnetized plasmas

    SciTech Connect

    Schlickeiser, R.

    2012-01-15

    A systematic calculation of the electromagnetic properties (Poynting vector, electromagnetic energy, and pressure) of the collective transverse fluctuations in unmagnetized plasmas with velocity-anisotropic plasma particle distributions functions is presented. Time-averaged electromagnetic properties for monochromatic weakly damped wave-like fluctuations and space-averaged electromagnetic properties for monochromatic weakly propagating and aperiodic fluctuations are calculated. For aperiodic fluctuations, the Poynting vector as well as the sum of the space-averaged electric and magnetic field energy densities vanish. However, aperiodic fluctuations possess a positive pressure given by its magnetic energy density. This finite pressure density p{sub a} of aperiodic fluctuations has important consequences for the dynamics of cosmic unmagnetized plasmas such as the intergalactic medium after reionization. Adopting the standard cosmological evolution model, we show that this additional pressure changes the expansion law of the universe leading to further deceleration. Negative vacuum pressure counterbalances this deceleration to an accelerating universe provided that the negative vacuum pressure is greater than 1.5p{sub a}, which we estimate to be of the order 2.1 {center_dot} 10{sup -16} dyn cm{sup -2}.

  19. Fluctuating magnetic field induced resonant activation

    SciTech Connect

    Mondal, Shrabani; Das, Sudip; Baura, Alendu; Bag, Bidhan Chandra

    2014-12-14

    In this paper, we have studied the properties of a Brownian particle at stationary state in the presence of a fluctuating magnetic field. Time dependence of the field makes the system thermodynamically open. As a signature of that the steady state distribution function becomes function of damping strength, intensity of fluctuations and constant parts of the applied magnetic field. It also depends on the correlation time of the fluctuating magnetic field. Our another observation is that the random magnetic field can induce the resonant activation phenomenon. Here correlation time is increased under the fixed variance of the fluctuating field. But if the correlation time (τ) increases under the fixed field strength then the mean first passage time rapidly grows at low τ and it almost converges at other limit. This is sharp contrast to the usual colored noise driven open system case where the mean first passage time diverges exponentially. We have also observed that a giant enhancement of barrier crossing rate occurs particularly at large strength of constant parts of the applied magnetic field even for very weak fluctuating magnetic field. Finally, break down of the Arrhenius result and disappearance of the Kramers’ turn over phenomenon may occur in the presence of a fluctuating magnetic field.

  20. Electromagnetic Fluctuations during Fast Reconnection in a Laboratory Plasma

    SciTech Connect

    Hantao Ji; Stephen Terry; Masaaki Yamada; Russell Kulsrud; Aleksey Kuritsyn; Yang Ren

    2003-02-11

    Clear evidence for a positive correlation is established between the magnitude of magnetic fluctuations in the lower-hybrid frequency range and enhancement of reconnection rates in a well-controlled laboratory plasma. The fluctuations belong to the right-hand polarized whistler wave branch, propagating obliquely to the reconnecting magnetic field, with a phase velocity comparable to the relative drift velocity between electrons and ions. The short coherence length and large variation along the propagation direction indicate their strongly nonlinear nature in three dimensions.

  1. Numerical simulation on level fluctuation in bloom casting mold with electromagnetic stirring

    NASA Astrophysics Data System (ADS)

    Zhang, H.; Ni, H. W.; Li, Y.; Zhao, Z. F.

    2016-03-01

    Based on a 380mm × 280mm bloom caster mold, the level fluctuation of steel-slag interface in the mold was simulated by the VOF model of commercial software Fluent. The effects of current intensity and frequency of EMS (electromagnetic stirring) on the level fluctuation in the mold were studied. The results show that whether or not with EMS, the maximum level fluctuation site of the mold occurs in the vicinity of the submerged entry nozzle. Compared with casting without EMS, molten steel flows horizontally rotatably under the action of the electromagnetic force by electromagnetic stirring, so the impact depth of molten steel decreases, then the level fluctuation slightly reduces, and the maximum level fluctuation value in the wide direction and the narrow direction of the mold, reduce from 4.24mm and 4.14mm to 4.04mm and 3.73mm respectively. With increasing intensity and frequency of current, the mold level fluctuation rises and the distribution uniformity of the level fluctuating amplitude worsens. The maximum level fluctuation enlarges by 0.18mm with raising the current intensity from 450A to 550A, but it enlarges by 0.79mm with 600A current intensity. The maximum level fluctuation enlarges by 0.15mm with raising the current frequency from 1.5Hz to 2.0Hz, but it quickly enlarges by 0.78mm with 2.5Hz current frequency. When the current strength and frequency are not more than 550A and 2.0Hz, level fluctuations are 4.00mm or less, which can meet requirements for controlling the bloom surface quality.

  2. Electromagnetically induced absorption via incoherent collisions

    SciTech Connect

    Yang Xihua; Sheng Jiteng; Xiao Min

    2011-10-15

    We conduct theoretical studies on electromagnetically induced absorption via incoherent collisions in an inhomogeneously broadened ladder-type three-level system with the density-matrix approach. The effects of the collision-induced coherence decay rates as well as the probe laser field intensity on the probe field absorption are examined. It is shown that with the increase of the collisional decay rates in a moderate range, a narrow dip due to electromagnetically induced transparency superimposed on the Doppler-broadened absorption background can be turned into a narrow peak under the conditions that the probe field intensity is not very weak as compared to the pump field, which results from the enhancement of constructive interference and suppression of destructive interference between one-photon and multiphoton transition pathways. The physical origin of the collision-assisted electromagnetically induced absorption is analyzed with a power-series solution of the density-matrix equations.

  3. Electromagnetic fluctuations in magnetized plasmas II: Extension of the theory for parallel wave vectors

    NASA Astrophysics Data System (ADS)

    Schlickeiser, R.; Ganz, A.; Kolberg, U.; Yoon, P. H.

    2015-10-01

    Starting from the recently derived general expressions for the electromagnetic fluctuation spectra (electric and magnetic field) from uncorrelated plasma particles in plasmas with an uniform magnetic field, the case of strictly parallel ( k ⊥ = 0 ) oriented wave vectors with the respect to the uniform magnetic field direction is investigated. To derive fluctuation spectra valid in the entire complex frequency plane, the relevant dispersion functions and form factors are analytically continued to negative values of the imaginary part of the frequency for arbitrary gyrotropic plasma particle distribution functions. The generalized fluctuation-dissipation theorems for non-collective fluctuations in isotropic equal-temperature thermal distribution functions for general complex values of the frequency of the fluctuations with parallel wave vectors are derived.

  4. Brownian motion in Robertson-Walker spacetimes from electromagnetic vacuum fluctuations

    SciTech Connect

    Bessa, Carlos H. G.; Bezerra, V. B.; Ford, L. H.

    2009-06-15

    We consider the effects of the vacuum fluctuations of a quantized electromagnetic field on particles in an expanding universe. We find that these particles typically undergo Brownian motion and acquire a nonzero mean squared velocity that depends on the scale factor of the universe. This Brownian motion can be interpreted as due to noncancellation of anticorrelated vacuum fluctuations in the time-dependent background spacetime. Alternatively, one can interpret this effect as the particles acquiring energy from the background spacetime geometry, a phenomenon that cannot occur in a static spacetime. We treat several types of coupling between the electromagnetic field and the particles and several model universes. We also consider both free particles, which, on the average, move on geodesics, and particles in bound systems. There are significant differences between these two cases, which illustrates that nongeodesic motion alters the effects of the vacuum fluctuations. We discuss the possible applications of this Brownian motion effect to cosmological scenarios.

  5. Electromagnetic fluctuation spectrum associated with the drift Alfven-cyclotron instability

    SciTech Connect

    Rha, Kicheol; Ryu, Chang-Mo; Yoon, Peter H.

    2012-07-15

    The present paper investigates the electromagnetic fluctuation spectrum associated with the drift Alfven-cyclotron instability by means of a two-dimensional particle-in-cell simulation, which may be plausibly associated with a current disruption event. The current disruption event shows localized high-amplitude electromagnetic fluctuations. In recent theories, these fluctuation characteristics are shown to correspond to the drift Alfven-cyclotron instability. A simulation is carried out to clarify this instability. The simulation shows that the drift Alfven-cyclotron instabilities are excited in two frequency regimes, a relatively low frequency mode propagating in a quasi-perpendicular direction while the second high-frequency branch propagating in a predominantly parallel propagation direction, consistent with observations as well as with a recent theory.

  6. Electromagnetic fluctuations in magnetized plasmas. I. The rigorous relativistic kinetic theory

    NASA Astrophysics Data System (ADS)

    Schlickeiser, R.; Yoon, P. H.

    2015-07-01

    Using the system of the Klimontovich and Maxwell equations, the general linear fluctuation theory for magnetized plasmas is developed. General expressions for the electromagnetic fluctuation spectra (electric and magnetic fields) from uncorrelated plasma particles in plasmas with a uniform magnetic field are derived, which are covariantly correct within the theory of special relativity. The general fluctuation spectra hold for plasmas of arbitrary composition, arbitrary momentum dependences of the plasma particle distribution functions, and arbitrary orientations of the wave vector with respect to the uniform magnetic field. Moreover, no restrictions on the values of the real and the imaginary parts of the frequency are made. The derived fluctuation spectra apply to both non-collective fluctuations and collective plasma eigenmodes in magnetized plasmas. In the latter case, kinetic equations for the components of fluctuating electric and magnetic fields in magnetized plasmas are derived that include the effect of spontaneous emission and absorption. In the limiting case of an unmagnetized plasmas, the general fluctuation spectra correctly reduce to the unmagnetized fluctuation spectra derived before.

  7. Electromagnetic fluctuations in magnetized plasmas. I. The rigorous relativistic kinetic theory

    SciTech Connect

    Schlickeiser, R. E-mail: yoonp@umd.edu; Yoon, P. H. E-mail: yoonp@umd.edu

    2015-07-15

    Using the system of the Klimontovich and Maxwell equations, the general linear fluctuation theory for magnetized plasmas is developed. General expressions for the electromagnetic fluctuation spectra (electric and magnetic fields) from uncorrelated plasma particles in plasmas with a uniform magnetic field are derived, which are covariantly correct within the theory of special relativity. The general fluctuation spectra hold for plasmas of arbitrary composition, arbitrary momentum dependences of the plasma particle distribution functions, and arbitrary orientations of the wave vector with respect to the uniform magnetic field. Moreover, no restrictions on the values of the real and the imaginary parts of the frequency are made. The derived fluctuation spectra apply to both non-collective fluctuations and collective plasma eigenmodes in magnetized plasmas. In the latter case, kinetic equations for the components of fluctuating electric and magnetic fields in magnetized plasmas are derived that include the effect of spontaneous emission and absorption. In the limiting case of an unmagnetized plasmas, the general fluctuation spectra correctly reduce to the unmagnetized fluctuation spectra derived before.

  8. Effect of the electromagnetic environment on current fluctuations in driven tunnel junctions

    NASA Astrophysics Data System (ADS)

    Frey, Moritz; Grabert, Hermann

    2016-07-01

    We examine current fluctuations in tunnel junctions driven by a superposition of a constant and a sinusoidal voltage source. In standard setups, the external voltage is applied to the tunneling element via an impedance providing an electromagnetic environment of the junction. The modes of this environment are excited by the time-dependent voltage and are the source of Johnson-Nyquist noise. We determine the autocorrelation function of the current flowing in the leads of the junction in the weak tunneling limit up to terms of second order in the tunneling Hamiltonian. The driven modes of the electromagnetic environment are treated exactly by means of a unitary transformation introduced recently. Particular emphasis is placed on the spectral function of the current fluctuations. The spectrum is found to comprise three contributions: a term arising from the Johnson-Nyquist noise of the environmental impedance, a part due to the shot noise of the tunneling element, and a third contribution which comes from the cross correlation between fluctuations caused by the electromagnetic environment and fluctuations of the tunneling current. All three parts of the spectral function occur already for devices under dc bias. The spectral function of ac driven tunneling elements can be determined from the result for a dc bias by means of a photoassisted tunneling relation of the Tien-Gordon type. Specific results are given for an Ohmic environment and for a junction driven through a resonator.

  9. Classical analog of electromagnetically induced transparency

    NASA Astrophysics Data System (ADS)

    Garrido Alzar, C. L.; Martinez, M. A. G.; Nussenzveig, P.

    2002-01-01

    We present a classical analog of electromagnetically induced transparency (EIT). In a system of just two coupled harmonic oscillators subject to a harmonic driving force, we reproduce the phenomenology observed in EIT. We also describe a simple experiment with two linearly coupled RLC circuits which can be incorporated into an undergraduate laboratory.

  10. Metamaterial transparency induced by cooperative electromagnetic interactions.

    PubMed

    Jenkins, Stewart D; Ruostekoski, Janne

    2013-10-01

    We propose a cooperative asymmetry-induced transparency, CAIT, formed by collective excitations in metamaterial arrays of discrete resonators. CAIT can display a sharp transmission resonance even when the constituent resonators individually exhibit broad resonances. We further show how dynamically reconfiguring the metamaterial allows one to actively control the transparency. While reminiscent of electromagnetically induced transparency, which can be described by independent emitters, CAIT relies on a cooperative response resulting from strong radiative couplings between the resonators.

  11. Whistler Cyclotron Electromagnetic Fluctuations in a Maxwellian and Tsallis-kappa-like Plasma

    NASA Astrophysics Data System (ADS)

    Vinas, A. F.; Moya, P. S.; Navarro, R.; Araneda, J. A.

    2014-12-01

    Observed electron velocity distributions in the Earth's magnetosphere and the solar wind exhibit a variety of non-thermal features which deviate from thermal equilibrium, for example, in the form of temperature anisotropies, suprathermal tail extensions, and field aligned beams. The state close to thermal equilibrium and its departure from it provides a source for spontaneous emissions of electromagnetic fluctuations, such as the whistler. Here we present a comparative analysis of whistler-cyclotron fluctuations based upon anisotropic plasma modeled with Maxwellian and Tsallis kappa-like particle distributions, to explain the correspondence relationship of the magnetic fluctuations as a function of the electron temperature and thermal anisotropy in the solar wind and magnetosphere plasmas. The analysis presented here considers correlation theory of the fluctuation-dissipation theorem and the dispersion relation of transverse fluctuations, with wave vectors parallel to the uniform background magnetic field, in a finite temperature anisotropic thermal bi-Maxwellian and non-thermal Tsallis-kappa-like magnetized electron-proton plasma. Dispersion analysis and stability thresholds are derived for these thermal and non-thermal distributions using plasma and field parameters relevant to the solar wind and magnetosphere environments. Our results indicate that there is an enhancement of the fluctuations level in the case of non-thermal distributions due to the effective higher-temperature and the excess of suprathermal particles. These results suggest that a comparison of the electromagnetic fluctuations due to thermal and non-thermal distributions provides a diagnostic signature by which inferences about the nature of the particle velocity distribution function can be ascertained without in-situ particle measurements.

  12. Spontaneous electromagnetic fluctuations in unmagnetized plasmas. II. Relativistic form factors of aperiodic thermal modes

    SciTech Connect

    Felten, T.; Schlickeiser, R.; Yoon, P. H.; Lazar, M.

    2013-05-15

    General expressions for the electromagnetic fluctuation spectra in unmagnetized plasmas are derived using fully relativistic dispersion functions and form factors for the important class of isotropic plasma particle distribution functions including in particular relativistic Maxwellian distributions. In order to obtain fluctuation spectra valid in the entire complex frequency plane, the proper analytical continuations of the unmagnetized form factors and dispersion functions are presented. The results are illustrated for the important special case of isotropic Maxwellian particle distribution functions providing in particular the thermal fluctuations of aperiodic modes. No restriction to the plasma temperature value is made, and the electromagnetic fluctuation spectra of ultrarelativistic thermal plasmas are calculated. The fully relativistic calculations also provide more general results in the limit of nonrelativistic plasma temperatures being valid in the entire complex frequency plane. They complement our earlier results in paper I and III of this series for negative values of the imaginary part of the frequency. A new collective, transverse, damped aperiodic mode with the damping rate γ∝−k{sup −5/3} is discovered in an isotropic thermal electron-proton plasma with nonrelativistic temperatures.

  13. Dephasing-Induced Control of Interference Nature in Three-Level Electromagnetically Induced Tansparency Systems

    PubMed Central

    Sun, Yong; Yang, Yaping; Chen, Hong; Zhu, Shiyao

    2015-01-01

    The influence of the dephasing on interference is investigated theoretically and experimentally in three-level electromagnetically induced transparency systems. The nature of the interference, constructive, no interference or destructive, can be controlled by adjusting the dephasing rates. This new phenomenon is experimentally observed in meta-atoms. The physics behind the dephasing-induced control of interference nature is the competing between stimulated emission and spontaneous emission. The random phase fluctuation due to the dephasing will result in the correlation and anti-correlation between the two dressed states, which will enhance and reduce the stimulated emission, respectively. PMID:26567708

  14. Strong ion energization by electromagnetic fluctuations in plasmoid-like magnetic structures.

    NASA Astrophysics Data System (ADS)

    Grigorenko, Elena

    2016-04-01

    Numerous studies based on data from many magnetospheric missions reported the observations of energetic ions with energies of hundreds of keV in the Earth magnetotail. The acceleration of charged particles to energies exceeding the potential drop across the tail can be produced by strong inductive electric fields generated in the course of transient processes related to changes of the magnetic field topology: e.g., magnetic reconnection, dipolarization, magnetic turbulence, and so on. The observations of energetic ion flows by Cluster/RAPID instruments in the near-Earth tail show the increase of H+, He+, and O+ fluxes in the energy range ≥130 keV during the periods of the tailward flows. The hardening of ion spectra is observed inside the plasmoid-like magnetic structures propagating tailward through the Cluster spacecraft. Simultaneously, the low-frequency electromagnetic fluctuations were observed in such structures. The analysis of 37 events demonstrated that the following factors are favorable for the ion energization: (1) the spatial scale of a plasmoid should exceed the thermal gyroradius of a given ion component in the plasmoid neutral plane; (2) the Power Spectral Density (PSD) of the magnetic fluctuations near the gyrofrequency of a particular ion component should exceed ~ 50.0 nT2/Hz for oxygen ions; while the energization of He+ and H+ takes place for much lower values of the PSD. The kinetic analysis of ion dynamics in the plasmoid-like magnetic configurations with the superimposed electromagnetic fluctuations similar to the observed ones confirms the importance of ion resonant interactions with the low-frequency electromagnetic fluctuations for ion energization inside plasmoids. The analysis also show that to be strongly accelerated ions do not need to pass a large distance in the duskward direction and the effective energization can be reached even at the localized source. Thus, ion acceleration by the electromagnetic fluctuations may smear the dawn

  15. Electromagnetic field fluctuations and optical nonlinearities in metal-dielectric composites

    NASA Astrophysics Data System (ADS)

    Sarychev, Andrey K.; Shalaev, Vladimir M.

    2000-09-01

    A scaling theory of local field fluctuations and optical nonlinearities is developed for random metal-dielectric composites near a percolation threshold. The theory predicts that in the optical and infrared spectral ranges the local fields are very inhomogeneous and consist of sharp peaks representing localized surface plasmons (s.p.). The localization maps the Anderson localization problem described by the random Hamiltonian with both on- and off-diagonal disorder. The local fields exceed the applied field by several orders of magnitudes resulting in giant enhancements of various optical phenomena. A new numerical method based on the developed theory is suggested. This method is employed to calculate the giant field fluctuations and enhancement of various optical processes in 2D metal-dielectric composites - semicontinuous metal films. The local field fluctuations appear to be highly correlated in space. These fluctuations result in dramatically enhanced Rayleigh and Raman light scattering. The scaling analysis is performed to describe the giant light scattering in a vicinity of the percolation threshold. The developed theory describes quantitatively enhancement of various nonlinear optical processes in percolation composites. It is shown that enhancement depends strongly on whether nonlinear multiphoton scattering includes an act of photon subtraction (annihilation). The magnitudes and spectral dependencies of enhancements in optical processes with photon subtraction, such as Raman and hyper-Raman scattering, Kerr refraction and four-wave mixing, are dramatically different from those processes without photon subtraction, such as sum-frequency and high-harmonic generation. Electromagnetic properties of metal-dielectric crystals and composites beyond the quasistatic approximation are also studied. Equations of macroscopic electromagnetism are presented for these systems. Both linear and nonlinear optical responses are considered in the case of a strong skin effect

  16. Solar wind thermally induced magnetic fluctuations.

    PubMed

    Navarro, R E; Moya, P S; Muñoz, V; Araneda, J A; F-Viñas, A; Valdivia, J A

    2014-06-20

    A kinetic description of Alfvén-cyclotron magnetic fluctuations for anisotropic electron-proton quasistable plasmas is studied. An analytical treatment, based on the fluctuation-dissipation theorem, consistently shows that spontaneous fluctuations in plasmas with stable distributions significantly contribute to the observed magnetic fluctuations in the solar wind, as seen, for example, in [S. D. Bale et al., Phys. Rev. Lett. 103, 211101 (2009)], even far below from the instability thresholds. Furthermore, these results, which do not require any adjustable parameters or wave excitations, are consistent with the results provided by hybrid simulations. It is expected that this analysis contributes to our understanding of the nature of magnetic fluctuations in the solar wind.

  17. Enhancement of residual stress by electromagnetic fluctuations: A quasi-linear study

    NASA Astrophysics Data System (ADS)

    Kaang, Helen H.; Jhang, Hogun; Singh, R.; Kim, Juhyung; Kim, S. S.

    2016-05-01

    A study is conducted on the impact of electromagnetic (EM) fluctuations on residual Reynolds stress in the context of the quasi-linear theory. We employ a fluid formulation describing EM ion temperature gradient turbulence. Analyses show that finite plasma β (=plasma thermal energy/magnetic energy) significantly increases the residual stress, potentially leading to the strong enhancement of flow generation in high β plasmas. We identify that this strong increase of residual stress originates from the reinforcement of radial ⟨ k ∥ ⟩ (=spectrally averaged parallel wavenumber) asymmetry due to the deformation of eigenfunctions near a rational surface.

  18. Electromagnetically induced gain in molecular systems

    NASA Astrophysics Data System (ADS)

    Mukherjee, Nandini; Patel, C. Kumar N.

    2009-12-01

    We report electromagnetically induced gain in a highly degenerate two-level rotational vibrational molecular system. Using two photon (Raman-type) interaction with right and left circularly polarized pump and probe waves, the Zeeman coherence is established within the manifold of degenerate sublevels belonging to a rotational vibrational eigenstate. We analytically and numerically calculate the third-order nonlinear optical susceptibility for a Doppler-broadened molecular transition for an arbitrary high rotational angular momentum (J≥20) . It is shown that for a Q -type open transition, a weak probe will experience an electromagnetically induced gain in presence of a strong copropagating pump wave. The inversionless gain originates due to cancellation of absorption from the interference of the coupled Λ - and V-type excitation channels in an N -type configuration. A detailed analysis of the optical susceptibility as a function of Doppler detuning explains how the gain bands are generated in a narrow transparency window from the overlapping contributions of different velocity groups. It is shown that the orientation dependent coherent interaction in presence of a strong pump induces narrow resonances for the probe susceptibility. The locations, intensity, and sign (positive or negative susceptibility) of these resonances are decided by the frequency detuning of the Doppler group and the strength of the coupling field. The availability of high power tunable quantum cascade lasers covering a spectral region from about 4 to 12μm opens up the possibility of investigating the molecular vibrational rotational transitions for a variety of coherent effects.

  19. Electromagnetically induced transparency with noisy lasers

    SciTech Connect

    Xiao Yanhong; Wang Tun; Baryakhtar, Maria; Jiang Liang; Lukin, Mikhail D.; Van Camp, Mackenzie; Crescimanno, Michael; Hohensee, Michael; Walsworth, Ronald L.; Phillips, David F.; Yelin, Susanne F.

    2009-10-15

    We demonstrate and characterize two coherent phenomena that can mitigate the effects of laser phase noise for electromagnetically induced transparency (EIT): a laser-power-broadening-resistant resonance in the transmitted intensity cross correlation between EIT optical fields, and a resonant suppression of the conversion of laser phase noise to intensity noise when one-photon noise dominates over two-photon-detuning noise. Our experimental observations are in good agreement with both an intuitive physical picture and numerical calculations. The results have wide-ranging applications to spectroscopy, atomic clocks, and magnetometers.

  20. Electromagnetically induced grating with maximal atomic coherence

    SciTech Connect

    Carvalho, Silvania A.; Araujo, Luis E. E. de

    2011-10-15

    We describe theoretically an atomic diffraction grating that combines an electromagnetically induced grating with a coherence grating in a double-{Lambda} atomic system. With the atom in a condition of maximal coherence between its lower levels, the combined gratings simultaneously diffract both the incident probe beam as well as the signal beam generated through four-wave mixing. A special feature of the atomic grating is that it will diffract any beam resonantly tuned to any excited state of the atom accessible by a dipole transition from its ground state.

  1. On the Transport and Radiative Properties of Plasmas with Small-Scale Electromagnetic Fluctuations

    NASA Astrophysics Data System (ADS)

    Keenan, Brett D.

    Plasmas with sub-Larmor-scale ("small-scale") electromagnetic fluctuations are a feature of a wide variety of high-energy-density environments, and are essential to the description of many astrophysical/laboratory plasma phenomena. Radiation from particles, whether they be relativistic or non-relativistic, moving through small-scale electromagnetic turbulence has spectral characteristics distinct from both synchrotron and cyclotron radiation. The radiation, carrying information on the statistical properties of the turbulence, is also intimately related to the particle diffusive transport. We investigate, both theoretically and numerically, the transport of non-relativistic and transrelativistic particles in plasmas with high-amplitude isotropic sub-Larmor-scale magnetic turbulence---both with and without a mean field component---and its relation to the spectra of radiation simultaneously produced by these particles. Furthermore, the transport of particles through small-scale electromagnetic turbulence---under certain conditions---resembles the random transport of particles---via Coulomb collisions---in collisional plasmas. The pitch-angle diffusion coefficient, which acts as an effective "collision" frequency, may be substantial in these, otherwise, collisionless environments. We show that this effect, colloquially referred to as the plasma "quasi-collisionality", may radically alter the expected radiative transport properties of candidate plasmas. We argue that the modified magneto-optic effects in these plasmas provide an attractive, novel, diagnostic tool for the exploration and characterization of small-scale electromagnetic turbulence. Lastly, we speculate upon the manner in which quasi-collisions may affect inertial confinement fusion (ICF), and other laser-plasma experiments. Finally, we show that mildly relativistic jitter radiation, from laser-produced plasmas, may offer insight into the underlying electromagnetic turbulence. Here we investigate the

  2. Physical origin of nonequilibrium fluctuation-induced forces in fluids.

    PubMed

    Kirkpatrick, T R; Ortiz de Zárate, J M; Sengers, J V

    2016-01-01

    Long-range thermal fluctuations appear in fluids in nonequilibrium states leading to fluctuation-induced Casimir-like forces. Two distinct mechanisms have been identified for the origin of the long-range nonequilibrium fluctuations in fluids subjected to a temperature or concentration gradient. One is a coupling between the heat or mass-diffusion mode with a viscous mode in fluids subjected to a temperature or concentration gradient. Another one is the spatial inhomogeneity of thermal noise in the presence of a gradient. We show that in fluids fluctuation-induced forces arising from mode coupling are several orders of magnitude larger than those from inhomogeneous noise.

  3. Spontaneous excitation of a circularly accelerated atom coupled to electromagnetic vacuum fluctuations

    SciTech Connect

    Jin, Yao; Hu, Jiawei; Yu, Hongwei

    2014-05-15

    We study, using the formalism proposed by Dalibard, Dupont-Roc and Cohen-Tannoudji, the contributions of the vacuum fluctuation and radiation reaction to the rate of change of the mean atomic energy for a circularly accelerated multilevel atom coupled to vacuum electromagnetic fields in the ultrarelativistic limit. We find that the balance between vacuum fluctuation and radiation reaction is broken, which causes spontaneous excitations of accelerated ground state atoms in vacuum. Unlike for a circularly accelerated atom coupled to vacuum scalar fields, the contribution of radiation reaction is also affected by acceleration, and this term takes the same form as that of a linearly accelerated atom coupled to vacuum electromagnetic fields. For the contribution of vacuum fluctuations, we find that in contrast to the linear acceleration case, terms proportional to the Planckian factor are replaced by those proportional to a non-Planck exponential term, and this indicates that the radiation perceived by a circularly orbiting observer is no longer thermal as is in the linear acceleration case. However, for an ensemble of two-level atoms, an effective temperature can be defined in terms of the atomic transition rates, which is found to be dependent on the transition frequency of the atom. Specifically, we calculate the effective temperature as a function of the transition frequency and find that in contrast to the case of circularly accelerated atoms coupled to the scalar field, the effective temperature in the current case is always larger than the Unruh temperature. -- Highlights: •We study the spontaneous excitation of a circularly accelerated atom. •Contribution of radiation reaction to the excitation is affected by acceleration. •The radiation perceived by a circularly orbiting observer is no longer thermal. •An effective temperature can be defined in terms of atomic transition rates. •Effective temperature is larger than Unruh temperature and frequency-dependent.

  4. Structural fluctuation of proteins induced by thermodynamic perturbation

    SciTech Connect

    Hirata, Fumio; Akasaka, Kazuyuki

    2015-01-28

    A theory to describe structural fluctuations of protein induced by thermodynamic perturbations, pressure, temperature, and denaturant, is proposed. The theory is formulated based on the three methods in the statistical mechanics: the generalized Langevin theory, the linear response theory, and the three dimensional interaction site model (3D-RISM) theory. The theory clarifies how the change in thermodynamic conditions, or a macroscopic perturbation, induces the conformational fluctuation, which is a microscopic property. The theoretical results are applied, on the conceptual basis, to explain the experimental finding by Akasaka et al., concerning the NMR experiment which states that the conformational change induced by pressure corresponds to structural fluctuations occurring in the ambient condition. A method to evaluate the structural fluctuation induced by pressure is also suggested by means of the 3D-RISM and the site-site Kirkwood-Buff theories.

  5. Wavelength mismatch effect in electromagnetically induced absorption

    NASA Astrophysics Data System (ADS)

    Bharti, Vineet; Wasan, Ajay; Natarajan, Vasant

    2016-07-01

    We present a theoretical investigation of the phenomenon of electromagnetically induced absorption (EIA) in a 4-level system consisting of vee and ladder subsystems. The four levels are coupled using one weak probe field, and two strong control fields. We consider an experimental realization using energy levels of Rb. This necessitates dealing with different conditions of wavelength mismatch-near-perfect match where all three wavelengths are approximately equal; partial mismatch where the wavelength of one control field is less than the other fields; and complete mismatch where all three wavelengths are unequal. We present probe absorption profiles with Doppler averaging at room temperature to account for experiments in a room temperature Rb vapor cell. Our analysis shows that EIA resonances can be studied using Rydberg states excited with diode lasers.

  6. Classical analogs of double electromagnetically induced transparency

    NASA Astrophysics Data System (ADS)

    Bai, Zhengyang; Hang, Chao; Huang, Guoxiang

    2013-03-01

    Double electromagnetically induced transparency (DEIT) in a four-level atomic system with tripod-type energy-level configuration is modeled by using two classical systems. The first is a set of three coupled harmonic oscillators subject to frictional forces and external drives and the second is a set of three coupled RLC circuits with electric resistors and alternating voltage sources. It is shown that both of the two classical systems have absorption spectra of DEIT similar to that of the four-level tripod-type atomic system. These classical analogies provide simple and intuitive physical description of quantum interference processes and can be used to illustrate experimental observations of the DEIT in quantum systems.

  7. Electromagnetic pulse-induced current measurement device

    NASA Astrophysics Data System (ADS)

    Gandhi, Om P.; Chen, Jin Y.

    1991-08-01

    To develop safety guidelines for exposure to high fields associated with an electromagnetic pulse (EMP), it is necessary to devise techniques that would measure the peak current induced in the human body. The main focus of this project was to design, fabricate, and test a portable, self-contained stand-on device that would measure and hold the peak current and the integrated change Q. The design specifications of the EMP-Induced Current Measurement Device are as follows: rise time of the current pulse, 5 ns; peak current, 20-600 A; charge Q, 0-20 microcoulombs. The device uses a stand-on parallel-plate bilayer sensor and fast high-frequency circuit that are well-shielded against spurious responses to high incident fields. Since the polarity of the incident peak electric field of the EMP may be either positive or negative, the induced peak current can also be positive or negative. Therefore, the device is designed to respond to either of these polarities and measure and hold both the peak current and the integrated charge which are simultaneously displayed on two separate 3-1/2 digit displays. The prototype device has been preliminarily tested with the EMP's generated at the Air Force Weapons Laboratory (ALECS facility) at Kirtland AFB, New Mexico.

  8. Trapped Electron Precession Shear Induced Fluctuation Decorrelation

    SciTech Connect

    T.S. Hahm; P.H. Diamond; E.-J. Kim

    2002-07-29

    We consider the effects of trapped electron precession shear on the microturbulence. In a similar way the strong E x B shear reduces the radial correlation length of ambient fluctuations, the radial variation of the trapped electron precession frequency can reduce the radial correlation length of fluctuations associated with trapped electrons. In reversed shear plasmas, with the explicit dependence of the trapped electron precession shearing rate on B(subscript)theta, the sharp radial gradient of T(subscript)e due to local electron heating inside qmin can make the precession shearing mechanism more effective, and reduce the electron thermal transport constructing a positive feedback loop for the T(subscript)e barrier formation.

  9. The JASE project: study of electromagnetic fields fluctuation from the Sun

    NASA Astrophysics Data System (ADS)

    Denies, Jonathan

    The Sun's energy has a beneficial interest for all but can be also destructive. On Earth under the protection of the magnetosphere, we can easily use this energy. Outside this protection, this situation is not the identical. Without this shield, astronauts are exposed to the radiations from Sun. Radiation is permanent. Sometimes, the Sun eject in his entourage more particles than usual increased to very high temperature. The most violent solar eruption can reach several million kilometres. During these solar eruptions, electric manifestation, named solar flares, escape from Sun. The JASE project (JUMP Astronaut Safety Experiment) consists into study electromagnetic fields fluctuation from the Sun during the JUMP Martian mission simulation in the Mars Desert Research Station (MDRS), a habitat installed by the Mars Society (MS) in the Utah desert. The aim of this study is to exploit the electromagnetic manifestation to develop a time model between the first observation of a solar flares and the mater ejection involved. This time model will give an approximation to the astronaut on the time remaining before the arrival of harmful particles. During this time, the astronaut must find a protected location (in the module life, in a cave etc.). To achieve this radio astronomy project, we need four main parts. The first one consists to design and assemble a small and portable radiotelescop developed to catch wave in a defined bandwidth. The frequency of interest is between 150 and 153Mhz. These frequencies correspond to an ejection of type II and III. The second one is to calibrate and test all device of this radiotelescop to take account of surrounding noise. These noises have several possible sources: the heat, local or global human activity, electronic, astronomical, etc. The next point consists to use this and detect all electromagnetic fluctuation. The last point consists to couple all sampling with data from a particle detector to develop the time model of the arrival

  10. Electrostatic and Electromagnetic Fluctuation in the Boundary Layer of Laboratory-Created Ionospheric Depletion

    NASA Astrophysics Data System (ADS)

    Liu, Y.; Cao, J.; Xu, L.; Zhang, X.

    2014-12-01

    Ionospheric depletions have been frequently artificially-created in the past decades from releasing attachment chemicals[Mendillo and Forbes, 1978]. In the early phase of the ionospheric depletion, a boundary layer of width of electric scale length emerged and separated the ionosphere into two regions, the ambient plasmas and the negative ion plasmas. In the localized boundary layer, there exists sharp electron gradients and strong sheared flows, which have a pronounced effect on the nonlinear evolution of many plasma systems. Therefore, it reflects essential research significance to study the boundary layer processes in an ionospheric depletion. However, until now, few experiments have specially designed and conducted to characterize and study those boundary layer processes[ Liu et al., 2014]. In the work, We studied the evolution of boundary layer in laboratory-created ionospheric depletions. These experiments were performed in plasma conditions with key dimensionless parameters scaled to those of the ionosphere. These electrons depletions were produced by releasing attachment chemicals into pre-existing plasmas. These plasmas were separated into two regions by a boundary layer of width of electric scale length. In the modeling ionospheric hole, localized boundary layer, those fluctuations of the electron density , floating potential, and magnetic field were investigated varying with the plasma pressure and the partial pressure of released chemicals. These fluctuations were recorded by Langmuir probes and magnetic probes. We analyzed the fluctuation using digital spectral analysis techniques, and electrostatic and electromagnetic fluctuations in the lower hybrid range were observed. These modes may be electron-ion hybrid(EIH) and whistler mode, respectively. The possibility will be discussed in more detail during the presentation. Reference Liu, Y., J. Cao, L. Xu, X. Zhang, P. Wang, J. Wang, Y. Du, and Z. Zheng (2014a), Coherent structure generated in the

  11. Bichromatic electromagnetically induced transparency in hot atomic vapors

    NASA Astrophysics Data System (ADS)

    Yan, Hui; Liao, Kai-Yu; Li, Jian-Feng; Du, Yan-Xiong; Zhang, Zhi-Ming; Zhu, Shi-Liang

    2013-05-01

    In a three-level Λ atomic system coupled by a symmetrical bichromatic laser field, a weak probe laser field shows multiple absorption peaks in the case of cold atoms. As for hot atomic vapors, we experimentally observe double symmetrical electromagnetically induced transparency windows instead of multiple absorption peaks. This abnormal spectrum is due to the Doppler averaging. The electromagnetically induced transparency windows observed here are useful for obtaining slow photons at different frequencies.

  12. Observation of an electromagnetically induced grating in cold sodium atoms

    NASA Astrophysics Data System (ADS)

    Mitsunaga, Masaharu; Imoto, Nobuyuki

    1999-06-01

    We have observed diffraction signals by a grating originating from electromagnetically induced transparency (EIT) in a three-level Λ system of cold sodium atoms. Theoretical and experimental analyses of this phenomenon, called the electromagnetically induced grating (EIG), have revealed that EIG spectra exhibit background-free, Lorentzian signal profiles regardless of the pump frequencies, making a clear contrast to the case of ordinary EIT spectra.

  13. Laser frequency locking based on Rydberg electromagnetically induced transparency

    NASA Astrophysics Data System (ADS)

    Yuechun, Jiao; Jingkui, Li; Limei, Wang; Hao, Zhang; Linjie, Zhang; Jianming, Zhao; Suotang, Jia

    2016-05-01

    We present a laser frequency locking to Rydberg transition with electromagnetically induced transparency (EIT) spectra in a room-temperature cesium vapor cell. Cesium levels 6S1/2, 6P3/2, and the nD5/2 state, compose a cascade three-level system, where a coupling laser drives Rydberg transition, and probe laser detects the EIT signal. The error signal, obtained by demodulating the EIT signal, is used to lock the coupling laser frequency to Rydberg transition. The laser frequency fluctuation, ∼0.7 MHz, is obtained after locking on, with the minimum Allan variance to be 8.9 × 10‑11. This kind of locking method can be used to stabilize the laser frequency to the excited transition. Project supported by the National Basic Research Program of China (Grant No. 2012CB921603), the National Natural Science Foundation of China (Grants Nos. 11274209, 61475090, 61378039, and 61378013), and the Research Project Supported by Shanxi Scholarship Council of China (Grant No. 2014-009).

  14. Laser frequency locking based on Rydberg electromagnetically induced transparency

    NASA Astrophysics Data System (ADS)

    Yuechun, Jiao; Jingkui, Li; Limei, Wang; Hao, Zhang; Linjie, Zhang; Jianming, Zhao; Suotang, Jia

    2016-05-01

    We present a laser frequency locking to Rydberg transition with electromagnetically induced transparency (EIT) spectra in a room-temperature cesium vapor cell. Cesium levels 6S1/2, 6P3/2, and the nD5/2 state, compose a cascade three-level system, where a coupling laser drives Rydberg transition, and probe laser detects the EIT signal. The error signal, obtained by demodulating the EIT signal, is used to lock the coupling laser frequency to Rydberg transition. The laser frequency fluctuation, ˜0.7 MHz, is obtained after locking on, with the minimum Allan variance to be 8.9 × 10-11. This kind of locking method can be used to stabilize the laser frequency to the excited transition. Project supported by the National Basic Research Program of China (Grant No. 2012CB921603), the National Natural Science Foundation of China (Grants Nos. 11274209, 61475090, 61378039, and 61378013), and the Research Project Supported by Shanxi Scholarship Council of China (Grant No. 2014-009).

  15. Fluctuation-induced linewidth in oscillator FEL

    NASA Astrophysics Data System (ADS)

    Shevchenko, Oleg A.; Vinokurov, Nikolay A.

    2004-08-01

    Due to relatively small number of microscopic radiators, the noise (spontaneous emission contribution to the radiation field) level in free electron lasers (FELs) is much more than in other types of lasers. The influence of this noise on the FEL linewidth is considered. A low gain optical klystron model is used. It is shown that in the most of practically interesting cases the noise-induced linewidth is negligible.

  16. Electromagnetic fluctuations of the whistler-cyclotron and firehose instabilities in a Maxwellian and Tsallis-kappa-like plasma

    NASA Astrophysics Data System (ADS)

    Viñas, Adolfo F.; Moya, Pablo S.; Navarro, Roberto E.; Valdivia, J. Alejandro; Araneda, Jaime A.; Muñoz, Víctor

    2015-05-01

    Observed electron velocity distributions in the Earth's magnetosphere and the solar wind exhibit a variety of nonthermal features which deviate from thermal equilibrium, for example, in the form of temperature anisotropies, suprathermal tail extensions, and field-aligned beams. The state close to thermal equilibrium and its departure from it provides a source for spontaneous emissions of electromagnetic fluctuations, such as the whistler. Here we present a comparative analysis of the electron whistler-cyclotron and firehose fluctuations based upon anisotropic plasma modeled with Maxwellian and Tsallis-kappa-like particle distributions, to explain the correspondence relationship of the magnetic fluctuations as a function of the electron temperature and thermal anisotropy in the solar wind and magnetosphere plasmas. The analysis presented here considers correlation theory of the fluctuation-dissipation theorem and the dispersion relation of transverse fluctuations, with wave vectors parallel to the uniform background magnetic field, in a finite temperature anisotropic thermal bi-Maxwellian and nonthermal Tsallis-kappa-like magnetized electron-proton plasma. Dispersion analysis and stability thresholds are derived for these thermal and nonthermal distributions using plasma and field parameters relevant to the solar wind and magnetosphere environments. Our results indicate that there is an enhancement of the fluctuations level in the case of nonthermal distributions due to the effective higher temperature and the excess of suprathermal particles. These results suggest that a comparison of the electromagnetic fluctuations due to thermal and nonthermal distributions provides a diagnostic signature by which inferences about the nature of the particle velocity distribution function can be ascertained without in situ particle measurements.

  17. 'Elastic' fluctuation-induced effects in smectic wetting films

    SciTech Connect

    Pikina, E. S.

    2009-11-15

    The Li-Kardar field theory approach is generalized to wetting smectic films and the 'elastic' fluctuation-induced interaction is obtained between the external flat bounding surface and distorted IA (isotropic liquid-smectic A) interface acting as an 'internal' (bulk) boundary of the wetting smectic film under the assumption that the IA interface is essentially 'softer' than the surface smectic layer. This field theory approach allows calculating the fluctuation-induced corrections in Hamiltonians of the so-called 'correlated' liquids confined by two surfaces, in the case where one of the bounding surfaces is 'rough' and with different types of surface smectic layer anchoring. We obtain that in practice, the account of thermal displacements of the smectic layers in a wetting smectic film reduces to the addition of two contributions to the IA interface Hamiltonian. The first, so-called local contribution describes the long-range thermal 'elastic' repulsion of the fluctuating IA interface from the flat bounding surface. The second, so-called nonlocal contribution is connected with the occurrence of an 'elastic' fluctuation-induced correction to the stiffness of the IA interface. An analytic expression for this correction is obtained.

  18. Electromagnetic field induced biological effects in humans.

    PubMed

    Kaszuba-Zwolińska, Jolanta; Gremba, Jerzy; Gałdzińska-Calik, Barbara; Wójcik-Piotrowicz, Karolina; Thor, Piotr J

    2015-01-01

    Exposure to artificial radio frequency electromagnetic fields (EMFs) has increased significantly in recent decades. Therefore, there is a growing scientific and social interest in its influence on health, even upon exposure significantly below the applicable standards. The intensity of electromagnetic radiation in human environment is increasing and currently reaches astronomical levels that had never before experienced on our planet. The most influential process of EMF impact on living organisms, is its direct tissue penetration. The current established standards of exposure to EMFs in Poland and in the rest of the world are based on the thermal effect. It is well known that weak EMF could cause all sorts of dramatic non-thermal effects in body cells, tissues and organs. The observed symptoms are hardly to assign to other environmental factors occurring simultaneously in the human environment. Although, there are still ongoing discussions on non-thermal effects of EMF influence, on May 31, 2011--International Agency for Research on Cancer (IARC)--Agenda of World Health Organization (WHO) has classified radio electromagnetic fields, to a category 2B as potentially carcinogenic. Electromagnetic fields can be dangerous not only because of the risk of cancer, but also other health problems, including electromagnetic hypersensitivity (EHS). Electromagnetic hypersensitivity (EHS) is a phenomenon characterized by the appearance of symptoms after exposure of people to electromagnetic fields, generated by EHS is characterized as a syndrome with a broad spectrum of non-specific multiple organ symptoms including both acute and chronic inflammatory processes located mainly in the skin and nervous systems, as well as in respiratory, cardiovascular systems, and musculoskeletal system. WHO does not consider the EHS as a disease-- defined on the basis of medical diagnosis and symptoms associated with any known syndrome. The symptoms may be associated with a single source of EMF

  19. Measurement of magnetic fluctuation-induced particle flux (invited)

    SciTech Connect

    Ding, W. X.; Brower, D. L.; Yates, T. Y.

    2008-10-15

    Magnetic field fluctuation-induced particle transport has been directly measured in the high-temperature core of the MST reversed field pinch plasma. Measurement of radial particle transport is achieved by combining various interferometry techniques, including Faraday rotation, conventional interferometry, and differential interferometry. It is observed that electron convective particle flux and its divergence exhibit a significant increase during a sawtooth crash. In this paper, we describe the basic techniques employed to determine the particle flux.

  20. Biomarkers of induced electromagnetic field and cancer.

    PubMed

    Behari, J; Paulraj, R

    2007-01-01

    The present article delineates the epidemiological and experimental studies of electromagnetic field which affects various tissues of human body. These affects lead to cell proliferation, which may lead to cancer formation. Certain biomarkers have been identified which are one way or the other responsible for tumor promotion or co-promotion. These are (i) melatonin, a hormone secreted by pineal gland, (ii) Ca2+, which is essential in the regulation of the resting membrane potential and in the sequence of events in synaptic excitation and neurotransmitter, release are affected by electromagnetic field, (iii) ornithine decarboxylase (ODC), a rate-limiting enzyme in the biosynthesis of polyamines, considered as a useful biological marker; over expression of ODC can cause cell transformation and enhancement of tumor promotion. (iv) protein kinase is an enzyme, which transfers phosphate groups from ATP to hydroxyl groups in the amino acid chains of acceptor proteins, and (v) Na+-K+ ATPase, which transports sodium and potassium ions across the membrane has a critical role in living cells. The various possible mechanisms depending upon non equilibrium thermodynamics, co-operativism, stochastic and resonance are discussed as possible models of signal transduction in cytosol, thereby controlling the transcription phenomena. Finally a mechanism comprising the extremely low frequency and radio frequency (RF)/microwave (MW) modulated field is compared.

  1. Decoherence induced by a fluctuating Aharonov-Casher phase

    SciTech Connect

    Lombardo, Fernando C.; Mazzitelli, Francisco D.; Villar, Paula I.

    2005-10-15

    Dipole interference is studied when atomic systems are coupled to classical electromagnetic fields. The interaction between the dipoles and the classical fields induces a time-varying Aharonov-Casher phase. Averaging over the phase generates a suppression of fringe visibility in the interference pattern. We show that, for suitable experimental conditions, the loss of contrast for dipoles can be observable and almost as large as the corresponding one for coherent electrons. We analyze different trajectories in order to show the dependence of the decoherence factor with the velocity of the particles.

  2. Thermoelectricity in polymer composites due to fluctuation-induced tunneling.

    PubMed

    Stedman, T; Wei, K; Nolas, G S; Woods, L M

    2015-11-01

    Transport in heavily-doped polymer composites, characterized by localized charge regions, is examined in light of the recent interest in polymers for thermoelectric applications. The developed fundamental transport theory describes carrier tunneling between charged localizations by taking into account thermally induced fluctuations of the applied potential. A range of characteristic behaviors corresponding to experimental data are described. Deviations from the Wiedemann-Franz law are also identified. This novel theory enables the determination of factors dominating the transport in polymers and a comparison to tunneling without thermal fluctuations is also provided. The obtained asymptotic expressions for the conductivity, Seebeck coefficient, and carrier thermal conductivity are particularly useful for elucidating possible routes for thermoelectric transport control and optimization. PMID:26437575

  3. Eustatic sea level fluctuations induced by polar wander

    NASA Technical Reports Server (NTRS)

    Sabadini, Roberto; Doglioni, Carlo; Yuen, David A.

    1990-01-01

    It is shown here that polar wander of a viscoelastic, stratified earth can induce global sea level fluctuations comparable to the short-term component in eustatic sea-level curves. The sign of these fluctuations, which are very sensitive to the rheological stratification, depends on the geographical location of the observation point; rises and falls in sea level can thus be coeval in different parts of the world. This finding is a distinct contrast to the main assumption underlying the reconstruction of eustatic curves, namely that global sea-level events produce the same depositional sequence everywhere. It is proposed that polar wander should be added to the list of geophysical mechanisms that can control the third-order cycles in sea level.

  4. Geometry-induced fluctuations of olfactory searches in bounded domains

    NASA Astrophysics Data System (ADS)

    Rodríguez, Juan Duque; Gómez-Ullate, David; Mejía-Monasterio, Carlos

    2014-04-01

    In olfactory search an immobile target emits chemical molecules at constant rate. The molecules are transported by the medium, which is assumed to be turbulent. Considering a searcher able to detect such chemical signals and whose motion follows the infotaxis strategy, we study the statistics of the first-passage time to the target when the searcher moves on a finite two-dimensional lattice of different geometries. Far from the target, where the concentration of chemicals is low, the direction of the searcher's first movement is determined by the geometry of the domain and the topology of the lattice, inducing strong fluctuations on the average search time with respect to the initial position of the searcher. The domain is partitioned in well-defined regions characterized by the direction of the first movement. If the search starts over the interface between two different regions, large fluctuations in the search time are observed.

  5. Explosive spread F caused by lightning-induced electromagnetic effects

    NASA Technical Reports Server (NTRS)

    Liao, C. P.; Freidberg, J. P.; Lee, M. C.

    1989-01-01

    Lightning-produced electromagnetic effects may produce significant modifications in the ionospheric plasmas. An outstanding phenomenon investigated in this paper is the so-called explosive spread F, whose close link with lightning has been identified (Woodman and Kudeki, 1984). Parametric instability excited by the lightning-induced whistler waves is proposed as a potential source mechanism causing the explosive spread F.

  6. Controllable motion of optical vortex arrays using electromagnetically induced transparency.

    PubMed

    Shwa, David; Shtranvasser, Evgeny; Shalibo, Yoni; Katz, Nadav

    2012-10-22

    We demonstrate control of the collective motion of an optical vortex array using an electromagnetically induced transparency media. Scanning the frequency detuning between the pump and probe fields changes the susceptibility of the media, producing a unique effective diffraction of the vortex array for each detuning. We measure several experimental configurations and compare them to numerical simulations.

  7. The Role of Higher-Order Modes on the Electromagnetic Whistler-Cyclotron Wave Fluctuations of Thermal and Non-Thermal Plasmas

    NASA Technical Reports Server (NTRS)

    Vinas, Adolfo F.; Moya, Pablo S.; Navarro, Roberto; Araneda, Jamie A.

    2014-01-01

    Two fundamental challenging problems of laboratory and astrophysical plasmas are the understanding of the relaxation of a collisionless plasmas with nearly isotropic velocity distribution functions and the resultant state of nearly equipartition energy density with electromagnetic plasma turbulence. Here, we present the results of a study which shows the role that higher-order-modes play in limiting the electromagnetic whistler-like fluctuations in a thermal and non-thermal plasma. Our main results show that for a thermal plasma the magnetic fluctuations are confined by regions that are bounded by the least-damped higher order modes. We further show that the zone where the whistler-cyclotron normal modes merges the electromagnetic fluctuations shifts to longer wavelengths as the beta(sub e) increases. This merging zone has been interpreted as the beginning of the region where the whistler-cyclotron waves losses their identity and become heavily damped while merging with the fluctuations. Our results further indicate that in the case of nonthermal plasmas, the higher-order modes do not confine the fluctuations due to the effective higher-temperature effects and the excess of suprathermal plasma particles. The analysis presented here considers the second-order theory of fluctuations and the dispersion relation of weakly transverse fluctuations, with wave vectors parallel to the uniform background magnetic field, in a finite temperature isotropic bi-Maxwellian and Tsallis-kappa-like magnetized electron-proton plasma. Our results indicate that the spontaneously emitted electromagnetic fluctuations are in fact enhanced over these quasi modes suggesting that such modes play an important role in the emission and absorption of electromagnetic fluctuations in thermal or quasi-thermal plasmas.

  8. Electromagnetically induced absorption in a three-resonator metasurface system

    PubMed Central

    Zhang, Xueqian; Xu, Ningning; Qu, Kenan; Tian, Zhen; Singh, Ranjan; Han, Jiaguang; Agarwal, Girish S.; Zhang, Weili

    2015-01-01

    Mimicking the quantum phenomena in metamaterials through coupled classical resonators has attracted enormous interest. Metamaterial analogs of electromagnetically induced transparency (EIT) enable promising applications in telecommunications, light storage, slow light and sensing. Although the EIT effect has been studied extensively in coupled metamaterial systems, excitation of electromagnetically induced absorption (EIA) through near-field coupling in these systems has only been sparsely explored. Here we present the observation of the EIA analog due to constructive interference in a vertically coupled three-resonator metamaterial system that consists of two bright and one dark resonator. The absorption resonance is one of the collective modes of the tripartite unit cell. Theoretical analysis shows that the absorption arises from a magnetic resonance induced by the near-field coupling of the three resonators within the unit cell. A classical analog of EIA opens up opportunities for designing novel photonic devices for narrow-band filtering, absorptive switching, optical modulation, and absorber applications. PMID:26023061

  9. Cosmological implications of modified gravity induced by quantum metric fluctuations

    NASA Astrophysics Data System (ADS)

    Liu, Xing; Harko, Tiberiu; Liang, Shi-Dong

    2016-08-01

    We investigate the cosmological implications of modified gravities induced by the quantum fluctuations of the gravitational metric. If the metric can be decomposed as the sum of the classical and of a fluctuating part, of quantum origin, then the corresponding Einstein quantum gravity generates at the classical level modified gravity models with a non-minimal coupling between geometry and matter. As a first step in our study, after assuming that the expectation value of the quantum correction can be generally expressed in terms of an arbitrary second order tensor constructed from the metric and from the thermodynamic quantities characterizing the matter content of the Universe, we derive the (classical) gravitational field equations in their general form. We analyze in detail the cosmological models obtained by assuming that the quantum correction tensor is given by the coupling of a scalar field and of a scalar function to the metric tensor, and by a term proportional to the matter energy-momentum tensor. For each considered model we obtain the gravitational field equations, and the generalized Friedmann equations for the case of a flat homogeneous and isotropic geometry. In some of these models the divergence of the matter energy-momentum tensor is non-zero, indicating a process of matter creation, which corresponds to an irreversible energy flow from the gravitational field to the matter fluid, and which is direct consequence of the non-minimal curvature-matter coupling. The cosmological evolution equations of these modified gravity models induced by the quantum fluctuations of the metric are investigated in detail by using both analytical and numerical methods, and it is shown that a large variety of cosmological models can be constructed, which, depending on the numerical values of the model parameters, can exhibit both accelerating and decelerating behaviors.

  10. Materials for damping the PTC-induced thermal fluctuations of the cold-head

    NASA Astrophysics Data System (ADS)

    Catarino, I.; Martins, D.; Sudiwala, R.

    2015-12-01

    The cold head on mechanical Pulse Tube Cryocoolers (PTCs) is subject to substantially less mechanical vibration and electromagnetic interference compared to that typically found in Gifford MacMahon coolers. However, thermal fluctuations at the PTC frequency are still present at the cold-head, typically at a level of 200 mK peak-to-peak at 1.4 Hz for a Cryomech Model PT405 cooler running at 4 K. It is highly desirable to damp out these fluctuations if PTCs are to be used successfully for running systems sensitive to such thermal fluctuations, for example, bolometeric detectors. We report here the characterization over the temperature range 2.5 K to 6 K of two materials, GOS (Gd2O2S) and GAP (GdAlO3), for use as low-pass thermal filters. These materials have antiferromagnetic transitions at around 4 K giving rise to an enhanced heat capacity and have a high thermal conductance. These are two highly desirable properties for thermal dampers in this application. Those materials were fired as ceramic discs to be tested as thermal dumpers. Thermal filter assemblies with discs of diameter 75 mm and thickness 2.5 mm and 1.6 mm (GOS and GAP, respectively) mounted in a PTC show thermal attenuation levels of x0.12 (GOS) and x0.11 (GAP) at 0.01Hz with a clean-side temperature of 4 K; the PTC induced fluctuations at 1.48 Hz are damped completely to within the noise limits (0.2 mK) of the thermometers. Experimentally determined thermal conductance and heat capacity data are reported. For this system, with a PTC cold-head (dirty-side) temperature of 3.3 K, a clean-side power dissipation of up to 30 mW is realized before its temperature rises above 4.2 K.

  11. Controlling the electromagnetically induced grating via spontaneously generated coherence

    NASA Astrophysics Data System (ADS)

    Bozorgzadeh, Forough; Sahrai, Mostafa; Khoshsima, Habib

    2016-09-01

    A new arrangement of an electromagnetically induced grating in a three-level Ladder-type atomic system with indirect incoherent pumping field is proposed. It is found that the diffraction intensity can efficiently be controlled by the spontaneously generated coherence (SGC). In addition, the diffraction intensity spectrum can dramatically be tuned by manipulating the coupling field intensity, resonance conditions, the rate of an indirect incoherent pumping field, and interaction length.

  12. High Frequency Atomic Magnetometer by Use of Electromagnetically Induced Transparency

    SciTech Connect

    Katsoprinakis, G.; Kominis, I. K.; Petrosyan, D.

    2006-12-08

    Atomic magnetometers have achieved magnetic sensitivities in the subfemtotesla regime. Their bandwidth is determined by the transverse spin relaxation rate, 1/T{sub 2}, which also determines the magnetic sensitivity. It is theoretically demonstrated that by using an electromagnetically induced transparent probe beam in a pump-probe atomic magnetometer, it is possible to operate the latter at frequencies much higher than its bandwidth, maintaining a high signal-to-noise ratio.

  13. Spontaneous electromagnetic fluctuations in unmagnetized plasmas. VI. Transverse, collective mode for arbitrary distribution functions

    SciTech Connect

    Felten, T.; Schlickeiser, R.

    2013-10-15

    Using the general expressions for the magnetic fluctuation spectrum from uncorrelated plasma particles, it is shown that an isotropic, unmagnetized plasma with arbitrary momentum distribution function spontaneously emits an aperiodic, collective, transverse, damped mode. The collective mode with the dispersion relation γ(k) provides the strongest contribution to the magnetic field fluctuation spectrum. Its existence has been proven before for Maxwellian and Lorentzian plasma distribution functions. Here it is demonstrated that this collective aperiodic mode exists in any isotropic unmagnetized, irrespective of the explicit form of the momentum distribution of plasma particles.

  14. Velocity Measurement by Scattering from Index of Refraction Fluctuations Induced in Turbulent Flows

    NASA Technical Reports Server (NTRS)

    Lading, Lars; Saffman, Mark; Edwards, Robert

    1996-01-01

    Induced phase screen scattering is defined as scatter light from a weak index of refraction fluctuations induced by turbulence. The basic assumptions and requirements for induced phase screen scattering, including scale requirements, are presented.

  15. Fluctuation-induced interactions in nematics with disordered anchoring energy.

    PubMed

    Haddadan, Fahimeh Karimi Pour; Naji, Ali; Shirzadiani, Nafiseh; Podgornik, Rudolf

    2014-12-17

    We examine fluctuation-induced (pseudo-Casimir) interactions in nematic liquid-crystalline films confined between two surfaces, where one of the surfaces imposes a strong homeotropic anchoring (ensuring a uniform mean director profile), while the other one is assumed to be a chemically disordered substrate exhibiting an annealed distribution of anchoring energies. We employ a saddle-point approximation to evaluate the free energy of interaction mediated between the two surfaces and investigate how the interaction force is influenced by the presence of disordered surface anchoring energy. It is shown that the disorder results in a renormalization of the effective surface anchoring parameter in a way that it leads to quantitative and qualitative changes (including a change of sign at intermediate inter-surface separations) in the pseudo-Casimir interaction force when compared with the interaction force in the absence of disorder.

  16. Engineering biphoton wave packets with an electromagnetically induced grating

    SciTech Connect

    Wen Jianming; Xiao Min; Zhai Yanhua; Du Shengwang

    2010-10-15

    We propose to shape biphoton wave packets with an electromagnetically induced grating in a four-level double-{Lambda} cold atomic system. We show that the induced hybrid grating plays an essential role in directing the new fields into different angular positions, especially for the zeroth-order diffraction. A number of interesting features appears in the shaped two-photon wave forms. For example, broadening or narrowing the spectrum would be possible in the proposed scheme even without the use of a cavity.

  17. Scattering of electromagnetic waves from random media with strong permittivity fluctuations. [with application to atmospheric turbulence effects on microwave remote sensing

    NASA Technical Reports Server (NTRS)

    Tsang, L.; Kong, J. A.

    1981-01-01

    By taking into account the singularity of the dyadic Green's function in the renormalization method, a theory is derived for vector electromagnetic wave propagation in a random medium with large permittivity fluctuations and with anisotropic correlation function. The strong fluctuation theory is then applied to a discrete scatterer problem in which the permittivity can assume only two values. The results are found to be consistent with those derived from discrete scatterer theory for all values of dielectric constants of the scatterers.

  18. The Formalism for Energy Changing Rate of an Accelerated Atom Coupled with Electromagnetic Vacuum Fluctuations

    NASA Astrophysics Data System (ADS)

    Zhang, Anwei

    2016-09-01

    The structure of the rate of variation of the atomic energy for an arbitrary stationary motion of the atom in interaction with a quantum electromagnetic field is investigated. Our main purpose is to rewrite the formalism in Zhu et al. (Phys Rev D 73:107501, 2006) and to deduce the general expressions of the Einstein A coefficients of an atom on an arbitrary stationary trajectory. The total rate of change of the energy and Einstein coefficients of the atom near a plate with finite temperature or acceleration are also investigated.

  19. Field Theoretical Investigation of Fluctuation-Induced Phenomena

    NASA Astrophysics Data System (ADS)

    Langsjoen, Luke Schell

    This thesis presents a field-theoretical investigation of the emergent properties of random fluctuations. We resolve a long-standing dilemma involving the ultraviolet divergences that often occur in Casimir calculations. We show that all formally divergent terms in the Casimir energy orgininate from geometrical properties of the boundary in question. Any material boundary will become transparent to sufficiently high-energy modes, and the formally divergent component of the energy is derived as an expansion in powers of this cutoff frequency. We demonstrate that the Casimir self-energy of a smooth boundary in two dimensions is a sum of two Weyl terms (exhibiting quadratic and logarithmic cutoff dependence), a geometrical term that is independent of the cutoff, and a non-geometrical intrinsic term. As by-products we resolve the puzzle of the divergent Casimir force on a ring and correct the sign of the coefficient of linear tension of a Dirichlet line predicted in earlier treatments. Next, we compute the generic mode sum that quantifies the effect on the spectrum of a harmonic field when a spherical shell is inserted into vacuum. We demonstrate that in the case of a scalar field obeying Dirichlet or Neumann boundary conditions on the shell surface the Casimir self-energy is cutoff-dependent while in the case of the electromagnetic field perturbed by a conductive shell the Casimir self-energy is universal. We also discuss generalized Casimir effects, for example an analog of the non-relativistic Casimir effect which can be realized in ferromagnets due to zero-point excitation of spin waves. We introduce a unique model for the Casimir effect of a boundary of finite thickness, with preliminary results. We present a calculation of the energy of N spinless non-interacting fermions confined to a one-dimensional interval. These results are shown to reinforce those obtained in the previous work of Kolomeisky et.al., [89]. Finally, we examine the classical Euler buckling

  20. Vector magnetometry based on electromagnetically induced transparency in linearly polarized light

    SciTech Connect

    Yudin, V. I.; Taichenachev, A. V.; Dudin, Y. O.; Velichansky, V. L.; Zibrov, A. S.; Zibrov, S. A.

    2010-09-15

    We develop a generalized principle of electromagnetically induced transparency (EIT) vector magnetometry based on high-contrast EIT resonances and the symmetry of atom-light interaction in the linearly polarized bichromatic fields. Operation of such vector magnetometer on the D{sub 1} line of {sup 87}Rb has been demonstrated. The proposed compass-magnetometer has an increased immunity to shifts produced by quadratic Zeeman and ac-Stark effects, as well as by atom-buffer gas and atom-atom collisions. In our proof-of-principle experiment the detected angular sensitivity to magnetic field orientation is 10{sup -3} deg/Hz{sup 1/2}, which is limited by laser intensity fluctuations, light polarization quality, and magnitude of the magnetic field.

  1. Highly-dispersive electromagnetic induced transparency in planar symmetric metamaterials.

    PubMed

    Lu, Xiqun; Shi, Jinhui; Liu, Ran; Guan, Chunying

    2012-07-30

    We propose, design and experimentally demonstrate highly-dispersive electromagnetically induced transparency (EIT) in planar symmetric metamaterials actively switched and controlled by angles of incidence. Full-wave simulation and measurement results show EIT phenomena, trapped-mode excitations and the associated local field enhancement of two symmetric metamaterials consisting of symmetrically split rings (SSR) and a fishscale (FS) metamaterial pattern, respectively, strongly depend on angles of incidence. The FS metamaterial shows much broader spectral splitting than the SSR metamaterial due to the surface current distribution variation.

  2. Mesoscopic Rydberg Gate Based on Electromagnetically Induced Transparency

    SciTech Connect

    Mueller, M.; Lesanovsky, I.; Zoller, P.; Weimer, H.; Buechler, H. P.

    2009-05-01

    We demonstrate theoretically a parallelized C-NOT gate which allows us to entangle a mesoscopic ensemble of atoms with a single control atom in a single step, with high fidelity and on a microsecond time scale. Our scheme relies on the strong and long-ranged interaction between Rydberg atoms triggering electromagnetically induced transparency. By this we can robustly implement a conditional transfer of all ensemble atoms between two logical states, depending on the state of the control atom. We outline a many-body interferometer which allows a comparison of two many-body quantum states by performing a measurement of the control atom.

  3. Pump/Probe Angular Dependence of Hanle Electromagnetically Induced Transparency

    NASA Astrophysics Data System (ADS)

    Jackson, Richard; Campbell, Kaleb; Crescimanno, Michael; Bali, Samir

    2015-05-01

    We investigate the dependence of Hanle Electromagnetically Induced Transparency (EIT) on angular separation between pump and probe field propagation directions in room-temperature Rb vapor. We observe the FWHM of the probe transmission spectrum and the amplitude of the EIT signal while varying the angular separation from 0 to 1 milliradian. Following the work of Ref., we examine potential applications in information storage and retrieval. We are grateful to Miami University for their generous financial support, and to the Miami University Instrumentation lab for their invaluable contributions.

  4. Magnetically coupled electromagnetically induced transparency analogy of dielectric metamaterial

    SciTech Connect

    Zhang, Fuli He, Xuan; Zhao, Qian; Lan, Chuwen; Zhou, Ji; Zhang, Weihong Qiu, Kepeng

    2014-03-31

    In this manuscript, we experimentally demonstrate magnetically coupled electromagnetically induced transparency (EIT) analogy effect inside dielectric metamaterial. In contrast to previous studies employed different metallic topological microstructures to introduce dissipation loss change, barium strontium titanate, and calcium titanate (CaTiO{sub 3}) are chosen as the bright and dark EIT resonators, respectively, due to their different intrinsic dielectric loss. Under incident magnetic field excitation, dielectric metamaterial exhibits an EIT-type transparency window around 8.9 GHz, which is accompanied by abrupt change of transmission phase. Numerical calculations show good agreement with experiment spectra and reveal remarkably increased group index, indicating potential application in slow light.

  5. Matched slow pulses using double electromagnetically induced transparency.

    PubMed

    MacRae, Andrew; Campbell, Geoff; Lvovsky, A I

    2008-11-15

    We implement double electromagnetically induced transparency (DEIT) in rubidium vapor using a tripod-shaped energy-level scheme consisting of hyperfine magnetic sublevels of the 5S1/2-->5P1/2 transition. We show experimentally that through the use of DEIT one can control the contrast of transparency windows as well as group velocities of the two signal fields. In particular, the group velocities can be equalized, which holds promise to greatly enhance nonlinear optical interaction between these fields.

  6. A fluctuation-induced plasma transport diagnostic based upon fast-Fourier transform spectral analysis

    NASA Technical Reports Server (NTRS)

    Powers, E. J.; Kim, Y. C.; Hong, J. Y.; Roth, J. R.; Krawczonek, W. M.

    1978-01-01

    A diagnostic, based on fast Fourier-transform spectral analysis techniques, that provides experimental insight into the relationship between the experimentally observable spectral characteristics of the fluctuations and the fluctuation-induced plasma transport is described. The model upon which the diagnostic technique is based and its experimental implementation is discussed. Some characteristic results obtained during the course of an experimental study of fluctuation-induced transport in the electric field dominated NASA Lewis bumpy torus plasma are presented.

  7. Electromagnetic interference-induced instability in CPP-GMR read heads

    NASA Astrophysics Data System (ADS)

    Khunkitti, P.; Siritaratiwat, A.; Kaewrawang, A.; Mewes, T.; Mewes, C. K. A.; Kruesubthaworn, A.

    2016-08-01

    Electromagnetic interference (EMI) has been a significant issue for the current perpendicular-to-the-plane giant magnetoresistance (CPP-GMR) read heads because it can cause magnetic failure. Furthermore, the magnetic noise induced by the spin transfer torque (STT) effect has played an important role in the CPP read heads because it can affect the stability of the heads. Accordingly, this work proposed an investigation of the magnetic instabilities induced by EMI through the STT effect in a CPP-GMR read head via micromagnetic simulations. The magnetization fluctuation caused by EMI was examined, and then, magnetic noise was evaluated by using power spectral density analysis. It was found that the magnetization orientation can be fluctuated by EMI in close proximity to the head. The results also showed a multimode spectral density. The main contributions of the spectral density were found to originate at the edges of the stripe height sides due to the characteristics of the demagnetization field inside the free layer. Hence, the magnetic instabilities produced by EMI become a significant factor that essentially impacts the reliability of the CPP-GMR read heads.

  8. Competing-fluctuation-induced anomalous magnetocaloric effects in perovskite manganites

    NASA Astrophysics Data System (ADS)

    Sakai, Hideaki; Taguchi, Yasujiro; Tokura, Yoshinori

    2010-03-01

    A magnetocaloric (MC) effect refers to the isothermal entropy change induced by applying (or removing) a magnetic field to the materials, which is a performance index of the magnetic refrigeration technology. In this study, the variation of MC effects has been systematically investigated for colossal magnetoresistive manganites R0.6Sr0.4MnO3 (R=La-Gd) by controlling the R-dependent one-electron bandwidth. With decreasing the bandwidth, the temperature profile of entropy change exhibits a larger peak at the ferromagnetic transition temperature and a steeper drop below it, due to the first-order nature of the transition promoted by a competing charge-orbital ordering instability. For the smallest-bandwidth systems adjacent to the metal- insulator phase boundary, a rectangular-shaped profile for the entropy change emerges with an anomalously wide temperature range. Model calculations have indicated that the bicritical fluctuation enhanced in the phase-competing region has a strong impact on such MC features [1]. [1] H. Sakai et al., J. Phys. Soc. Jpn. 78, 113708 (2009).

  9. Spin jam induced by quantum fluctuations in a frustrated magnet

    PubMed Central

    Yang, Junjie; Samarakoon, Anjana; Dissanayake, Sachith; Ueda, Hiroaki; Klich, Israel; Iida, Kazuki; Pajerowski, Daniel; Butch, Nicholas P.; Huang, Q.; Copley, John R. D.; Lee, Seung-Hun

    2015-01-01

    Since the discovery of spin glasses in dilute magnetic systems, their study has been largely focused on understanding randomness and defects as the driving mechanism. The same paradigm has also been applied to explain glassy states found in dense frustrated systems. Recently, however, it has been theoretically suggested that different mechanisms, such as quantum fluctuations and topological features, may induce glassy states in defect-free spin systems, far from the conventional dilute limit. Here we report experimental evidence for existence of a glassy state, which we call a spin jam, in the vicinity of the clean limit of a frustrated magnet, which is insensitive to a low concentration of defects. We have studied the effect of impurities on SrCr9pGa12-9pO19 [SCGO(p)], a highly frustrated magnet, in which the magnetic Cr3+ (s = 3/2) ions form a quasi-2D triangular system of bipyramids. Our experimental data show that as the nonmagnetic Ga3+ impurity concentration is changed, there are two distinct phases of glassiness: an exotic glassy state, which we call a spin jam, for the high magnetic concentration region (p>0.8) and a cluster spin glass for lower magnetic concentration (p<0.8). This observation indicates that a spin jam is a unique vantage point from which the class of glassy states of dense frustrated magnets can be understood. PMID:26324917

  10. Spin jam induced by quantum fluctuations in a frustrated magnet.

    PubMed

    Yang, Junjie; Samarakoon, Anjana; Dissanayake, Sachith; Ueda, Hiroaki; Klich, Israel; Iida, Kazuki; Pajerowski, Daniel; Butch, Nicholas P; Huang, Q; Copley, John R D; Lee, Seung-Hun

    2015-09-15

    Since the discovery of spin glasses in dilute magnetic systems, their study has been largely focused on understanding randomness and defects as the driving mechanism. The same paradigm has also been applied to explain glassy states found in dense frustrated systems. Recently, however, it has been theoretically suggested that different mechanisms, such as quantum fluctuations and topological features, may induce glassy states in defect-free spin systems, far from the conventional dilute limit. Here we report experimental evidence for existence of a glassy state, which we call a spin jam, in the vicinity of the clean limit of a frustrated magnet, which is insensitive to a low concentration of defects. We have studied the effect of impurities on SrCr9pGa12-9pO19 [SCGO(p)], a highly frustrated magnet, in which the magnetic Cr(3+) (s = 3/2) ions form a quasi-2D triangular system of bipyramids. Our experimental data show that as the nonmagnetic Ga(3+) impurity concentration is changed, there are two distinct phases of glassiness: an exotic glassy state, which we call a spin jam, for the high magnetic concentration region (p > 0.8) and a cluster spin glass for lower magnetic concentration (p < 0.8). This observation indicates that a spin jam is a unique vantage point from which the class of glassy states of dense frustrated magnets can be understood.

  11. Cell membrane thermal gradients induced by electromagnetic fields

    NASA Astrophysics Data System (ADS)

    Garner, Allen L.; Deminsky, Maxim; Bogdan Neculaes, V.; Chashihin, V.; Knizhnik, Andrey; Potapkin, Boris

    2013-06-01

    While electromagnetic fields induce structural changes in cell membranes, particularly electroporation, much remains to be understood about membrane level temperature gradients. For instance, microwaves induce cell membrane temperature gradients (∇T) and bioeffects with little bulk temperature change. Recent calculations suggest that nanosecond pulsed electric fields (nsPEFs) may also induce such gradients that may additionally impact the electroporation threshold. Here, we analytically and numerically calculate the induced ∇T as a function of pulse duration and pulse repetition rate. We relate ∇T to the thermally induced cell membrane electric field (Em) by assuming the membrane behaves as a thermoelectric such that Em ˜ ∇T. Focusing initially on applying nsPEFs to a uniform membrane, we show that reducing pulse duration and increasing pulse repetition rate (or using higher frequency for alternating current (AC) fields) maximizes the magnitude and duration of ∇T and, concomitantly, Em. The maximum ∇T initially occurs at the interface between the cell membrane and extracellular fluid before becoming uniform across the membrane, potentially enabling initial molecular penetration and subsequent transport across the membrane. These results, which are equally applicable to AC fields, motivate further studies to elucidate thermoelectric behavior in a model membrane system and the coupling of the Em induced by ∇T with that created directly by the applied field.

  12. Correlation between intensity fluctuations of light generated by scattering of Young’s diffractive electromagnetic waves by a quasi-homogeneous, anisotropic medium

    NASA Astrophysics Data System (ADS)

    Li, Jia; Chen, Feinan

    2016-11-01

    Based on the first-order Born approximation, formulas are derived for the correlation between intensity fluctuations (CIF) of light generated by a Young’s diffractive electromagnetic wave scattered by a spatially quasi-homogeneous (QH), anisotropic medium. It is shown that the CIF of the scattered field can be written as the summation of the Fourier transforms of the strengths and normalized correlation coefficients (NCCs) of the scattering potentials. The differences between our results and those obtained in the previous literature are discussed. Our results might be important in investigating the high-order intensity correlation of an electromagnetic wave scattered from a 3D anisotropic object.

  13. Manipulation of electromagnetically induced transparency by planar metamaterial

    NASA Astrophysics Data System (ADS)

    Yang, Helin; Hu, Sen; Liu, Dan; Lin, Hai; Xiao, Boxun; Chen, Jiao

    2016-02-01

    The transmission characteristics of a planar metamaterial, composed of a metal ring and a regular trigonometry-star-rod (TSR), have been numerically and experimentally investigated in this paper. By rotating the TSR with different angles, this structure will appear to be symmetric or asymmetric toward the incident waves and then finely controls the coupling between the ring and the TSR. Thus, the transmission spectrum of our proposed structure can exhibit an electromagnetically induced transparency (EIT)-like spectral response in microwave region. Owing to the C3 rotational symmetry of the structure, an on-to-off active modulation of the EIT-like transparency window can be realized, and it may serve as the base for a microwave optical switching. Equivalent electric dipole moments couplings are employed to explain the transmission properties. In all, our work provides a way to obtain EIT-like effect, and it may achieve potential applications in filters, sensing and some other microwave devices.

  14. Electromagnetically induced optical anisotropy of an ultracold atomic medium

    NASA Astrophysics Data System (ADS)

    Datsyuk, V. M.; Sokolov, I. M.; Kupriyanov, D. V.; Havey, M. D.

    2008-03-01

    We consider radiative transport in ultracold atomic systems under conditions of electromagnetically induced transparency. We calculate the macroscopic susceptibility and scattering tensors of the light and show that essential anisotropic optical properties such as dichroism and birefringence naturally appear. In such a case, light propagation through a spatially nonhomogeneous atomic cloud is considered for an arbitrary direction of the probe light. We determine the polarization properties of the coherently transmitted probe light as well as the polarization dependence of light incoherently scattered in an arbitrary direction. Both the steady state regime and time-dependent case are discussed. Concrete calculations are performed for the case of an inhomogeneous and ultracold sample of R87b atoms.

  15. Tailoring electromagnetically induced transparency with different coupling mechanisms

    PubMed Central

    Li, Hai-ming; Liu, Shao-bin; Wang, Shen-yun; Liu, Si-yuan; Hu, Yan; Li, Hai-bin

    2016-01-01

    Tailoring electromagnetically induced transparency with two different coupling mechanisms has been numerically demonstrated. The results show that EIT based on simultaneous electric resonance and magnetic resonance has relatively larger coupling distance compared with that based on electric resonance near field coupling to magnetic resonance. The relatively large coupling distance is due to the relatively small susceptibility change. For EIT based on simultaneous electric resonance and magnetic resonance, not only incident electric field but also the incident magnetic field pays a role on the susceptibility of system. The influence of the incident magnetic field leads to relatively smaller susceptibility change compared with that based on electric resonance near field coupling to magnetic resonance. PMID:26900016

  16. All-dielectric metasurface analogue of electromagnetically induced transparency

    NASA Astrophysics Data System (ADS)

    Yang, Yuanmu; Kravchenko, Ivan I.; Briggs, Dayrl P.; Valentine, Jason

    2014-12-01

    Metasurface analogues of electromagnetically induced transparency (EIT) have been a focus of the nanophotonics field in recent years, due to their ability to produce high-quality factor (Q-factor) resonances. Such resonances are expected to be useful for applications such as low-loss slow-light devices and highly sensitive optical sensors. However, ohmic losses limit the achievable Q-factors in conventional plasmonic EIT metasurfaces to values <~10, significantly hampering device performance. Here we experimentally demonstrate a classical analogue of EIT using all-dielectric silicon-based metasurfaces. Due to extremely low absorption loss and coherent interaction of neighbouring meta-atoms, a Q-factor of 483 is observed, leading to a refractive index sensor with a figure-of-merit of 103. Furthermore, we show that the dielectric metasurfaces can be engineered to confine the optical field in either the silicon resonator or the environment, allowing one to tailor light-matter interaction at the nanoscale.

  17. Entangler via electromagnetically induced transparency with an atomic ensemble.

    PubMed

    Yang, Xihua; Zhou, Yuanyuan; Xiao, Min

    2013-12-11

    Quantum entanglement plays an essential role in quantum information processing and quantum networks. One of the commonly-used methods to generate multiple entangled fields is to employ polarizing beam splitters. However, nonclassical input light fields are required and the generated entangled fields are always degenerate in such case. Here, we present a proof-of-principle demonstration of an efficient and convenient way to entangle multiple light fields via electromagnetically induced transparency (EIT) in an atomic ensemble. The atomic spin wave, produced through EIT in the Λ-type atomic system, can be described by a Bose operator and can act as an entangler. With such an entangler, any desired number of nondegenerate narrow-band continuous-variable entangled fields, in principle, can be generated through stimulated Raman scattering processes. This scheme holds great promise for applications in scalable quantum communication and quantum networks. PACS: 42.50.Gy, 03.67.Bg, 42.50.Dv, 42.65.Lm.

  18. Phase measurement of fast light pulse in electromagnetically induced absorption.

    PubMed

    Lee, Yoon-Seok; Lee, Hee Jung; Moon, Han Seb

    2013-09-23

    We report the phase measurement of a fast light pulse in electromagnetically induced absorption (EIA) of the 5S₁/₂ (F = 2)-5P₃/₂ (F' = 3) transition of ⁸⁷Rb atoms. Using a beat-note interferometer method, a stable measurement without phase dithering of the phase of the probe pulse before and after it has passed through the EIA medium was achieved. Comparing the phases of the light pulse in air and that of the fast light pulse though the EIA medium, the phase of the fast light pulse at EIA resonance was not shifted and maintained to be the same as that of the free-space light pulse. The classical fidelity of the fast light pulse according to the advancement of the group velocity by adjusting the atomic density was estimated to be more than 97%.

  19. Tunable Transmission-Line Metamaterials Mimicking Electromagnetically Induced Transparency

    NASA Astrophysics Data System (ADS)

    Feng, T. H.; Han, H. P.

    2016-11-01

    Tunable transmission-line (TL) metamaterials mimicking electromagnetically induced transparency (EIT) have been studied. Firstly, two types of tunable TL EIT-like metamaterial, based on the double split-ring resonator (DSRR) and single split-ring resonator (SSRR), were fabricated and their transmission properties carefully compared. The results showed that the transmittance maximum was almost invariable with shift of the transparency window for the tunable DSRR-based TL EIT-like metamaterial, but for the tunable SSRR-based TL EIT-like metamaterial, the transmittance maximum gradually diminished with shift of the transparency window toward the center of the absorption band. Moreover, the reason for these different transmission properties was explored, revealing that the reduction of the transmittance maximum of the transparency window for the tunable SSRR-based TL EIT-like metamaterial is mainly due to energy loss caused by the resistance of the loaded varactor diodes.

  20. Slow light with electromagnetically induced transparency in optical fibre

    NASA Astrophysics Data System (ADS)

    Muhamad Hatta, Agus; Kamli, Ali A.; Al-Hagan, Ola A.; Moiseev, Sergey A.

    2015-08-01

    Slow light with electromagnetically induced transparency (EIT) in the core of optical fibre containing three-level atoms is investigated. The guided modes are treated in the weakly guiding approximation which renders the analysis into a manageable form. The transparency window and permittivity profile of the core due to the strong pump field in the EIT scheme is calculated. For a specific permittivity profile of the core due to EIT, the propagation constant of the weak signal field and spatial shape of fundamental guided mode are calculated by solving the vector wave equation using the finite difference method. It is found that the transparency window and slow light field can be controlled via the optical fibre parameters. The reduced group velocity of slow light in this configuration is useful for many technological applications such as optical memories, effective control of single photon fields, optical buffers and delay lines.

  1. Light scattering under conditions of nonstationary electromagnetically induced transparency

    SciTech Connect

    Larionov, N V; Sokolov, I M

    2007-12-31

    The propagation of probe radiation pulses in ultracold atomic ensembles is studied theoretically under conditions of electromagnetically induced transparency. The pulse 'stopping' process is considered which takes place upon nonadiabatic switching off and subsequent switching on the control field. We analysed the formation of an inverted recovered probe radiation pulse, i.e. the pulse propagating in the direction opposite to the propagation direction before the pulse stopping. Based on this analysis, a scheme is proposed for lidar probing atomic or molecular clouds in which the probe pulse penetrates into a cloud over the specified depth, while information on the cloud state is obtained from the parameters of the inverted pulse. Calculations are performed for an ensemble of {sup 87}Rb atoms. (fifth seminar in memory of d.n. klyshko)

  2. Electromagnetically Induced Transparency in Potassium Vapors: Features and Restrictions

    NASA Astrophysics Data System (ADS)

    Sargsyan, A.; Petrov, P. A.; Vartanyan, T. A.; Sarkisyan, D.

    2016-03-01

    Features of electromagnetically induced transparency (EIT) in potassium vapors at the D1 line of the 39K isotope are studied. EIT resonances with a subnatural width of 3.5 MHz have been recorded upon excitation by two independent narrow-band diode lasers in a 1-cm-long cell filled with a natural mixture of potassium isotopes and buffer gas. The splitting of EIT resonances in potassium vapors in longitudinal and transverse magnetic fields has been studied for the first time. The splitted components also have a subnatural width. The smallness of the coupling factor of the hyperfine structure in 39K atoms leads to a transition to the Paschen—Back regime at relatively weaker magnetic fields than in the case of Cs, Rb, and Na atoms. Practical applications of the phenomena under study are noted. The theoretical model well explains the experiment.

  3. Tunable Transmission-Line Metamaterials Mimicking Electromagnetically Induced Transparency

    NASA Astrophysics Data System (ADS)

    Feng, T. H.; Han, H. P.

    2016-08-01

    Tunable transmission-line (TL) metamaterials mimicking electromagnetically induced transparency (EIT) have been studied. Firstly, two types of tunable TL EIT-like metamaterial, based on the double split-ring resonator (DSRR) and single split-ring resonator (SSRR), were fabricated and their transmission properties carefully compared. The results showed that the transmittance maximum was almost invariable with shift of the transparency window for the tunable DSRR-based TL EIT-like metamaterial, but for the tunable SSRR-based TL EIT-like metamaterial, the transmittance maximum gradually diminished with shift of the transparency window toward the center of the absorption band. Moreover, the reason for these different transmission properties was explored, revealing that the reduction of the transmittance maximum of the transparency window for the tunable SSRR-based TL EIT-like metamaterial is mainly due to energy loss caused by the resistance of the loaded varactor diodes.

  4. Multiplexed image storage by electromagnetically induced transparency in a solid

    NASA Astrophysics Data System (ADS)

    Heinze, G.; Rentzsch, N.; Halfmann, T.

    2012-11-01

    We report on frequency- and angle-multiplexed image storage by electromagnetically induced transparency (EIT) in a Pr3+:Y2SiO5 crystal. Frequency multiplexing by EIT relies on simultaneous storage of light pulses in atomic coherences, driven in different frequency ensembles of the inhomogeneously broadened solid medium. Angular multiplexing by EIT relies on phase matching of the driving laser beams, which permits simultaneous storage of light pulses propagating under different angles into the crystal. We apply the multiplexing techniques to increase the storage capacity of the EIT-driven optical memory, in particular to implement multiplexed storage of larger two-dimensional amounts of data (images). We demonstrate selective storage and readout of images by frequency-multiplexed EIT and angular-multiplexed EIT, as well as the potential to combine both multiplexing approaches towards further enhanced storage capacities.

  5. Double electromagnetically induced transparency and its application in quantum information

    NASA Astrophysics Data System (ADS)

    Wang, Zeng-Bin; Marzlin, Karl-Peter; Sanders, Barry C.

    2006-08-01

    Strong optical cross-phase modulation (XPM) for weak fields is tremendously important for optical quantum information (QI) processing and for all-optical switches in classical communication. A sufficiently large XPM would allow the design of deterministic controlled quantum gates for photonic qubits and thus enable universal optical quantum computation. Recently, several proposals have been brought forward to create large XPM using double electromagnetically induced transparency (DEIT) in which two weak signal light pulses travel at equally slow group velocity, but creating DEIT still poses an experimental challenge. We give a brief overview about DEIT and discuss its applications and limitations. A scheme that combines the best features of previous proposals and optimizes the large XPM parameter for DEIT schemes is outlined. Finally we devise a scheme to perform universal quantum information processing, which respects the bound on the achievable nonlinearity and addresses the requirement of quantum error correction.

  6. Electromagnetically induced transparency and fluorescence in blockaded Rydberg atomic system

    SciTech Connect

    Li, Cheng; Zheng, Huaibin; Zhang, Zhaoyang; Yao, Xin; Zhang, Yunzhe; Zhang, Yiqi; Zhang, Yanpeng

    2013-10-28

    We investigate the interaction between dark states and Rydberg excitation blockade by using electromagnetically induced transparency (EIT), fluorescence, and four-wave mixing (FWM) signals both theoretically and experimentally. By scanning the frequency detunings of the probe and dressing fields, respectively, we first observe these signals (three coexisting EIT windows, two fluorescence signals, and two FWM signals) under Rydberg excitation blockade. Next, frequency detuning dependences of these signals are obtained, in which the modulated results are well explained by introducing the dressing effects (leading to the dark states) with the corrected factor of the Rydberg excitation blockade. In addition, the variations by changing the principal quantum number n of Rydberg state shown some interesting phenomena resulting from Rydberg blockade are observed. The unique nature of such blockaded signals can have potential application in the demonstration of quantum computing.

  7. Theoretical analysis of dipole-induced electromagnetic transparency

    NASA Astrophysics Data System (ADS)

    Puthumpally-Joseph, Raiju; Atabek, Osman; Sukharev, Maxim; Charron, Eric

    2015-04-01

    We present a detailed, realistic analysis of the implementation of a proposal for dipole-induced electromagnetic transparency (DIET) [R. Puthumpally-Joseph, M. Sukharev, O. Atabek, and E. Charron, Phys. Rev. Lett. 113, 163603 (2014), 10.1103/PhysRevLett.113.163603] using an ensemble of cold atoms at high density. Using both direct numerical simulations and simple analytical models, we show how, in a realistic N -level quantum system, narrow transparency windows can appear at large densities. The existence of such windows is attributed to quantum interference effects in overlapping resonances. Our analysis is applied to the D1 transition of Rb atoms, and we show that, at high densities, Rb can behave like a simple three-level emitter exhibiting all the properties of DIET. Some interesting effects such as slow light are also presented, and their limits in the context of DIET are discussed

  8. Electromagnetically induced transparency and slow light with optomechanics.

    PubMed

    Safavi-Naeini, A H; Mayer Alegre, T P; Chan, J; Eichenfield, M; Winger, M; Lin, Q; Hill, J T; Chang, D E; Painter, O

    2011-04-01

    Controlling the interaction between localized optical and mechanical excitations has recently become possible following advances in micro- and nanofabrication techniques. So far, most experimental studies of optomechanics have focused on measurement and control of the mechanical subsystem through its interaction with optics, and have led to the experimental demonstration of dynamical back-action cooling and optical rigidity of the mechanical system. Conversely, the optical response of these systems is also modified in the presence of mechanical interactions, leading to effects such as electromagnetically induced transparency (EIT) and parametric normal-mode splitting. In atomic systems, studies of slow and stopped light (applicable to modern optical networks and future quantum networks) have thrust EIT to the forefront of experimental study during the past two decades. Here we demonstrate EIT and tunable optical delays in a nanoscale optomechanical crystal, using the optomechanical nonlinearity to control the velocity of light by way of engineered photon-phonon interactions. Our device is fabricated by simply etching holes into a thin film of silicon. At low temperature (8.7 kelvin), we report an optically tunable delay of 50 nanoseconds with near-unity optical transparency, and superluminal light with a 1.4 microsecond signal advance. These results, while indicating significant progress towards an integrated quantum optomechanical memory, are also relevant to classical signal processing applications. Measurements at room temperature in the analogous regime of electromagnetically induced absorption show the utility of these chip-scale optomechanical systems for optical buffering, amplification, and filtering of microwave-over-optical signals. PMID:21412237

  9. Effective cosmological constant induced by stochastic fluctuations of Newton's constant

    NASA Astrophysics Data System (ADS)

    de Cesare, Marco; Lizzi, Fedele; Sakellariadou, Mairi

    2016-09-01

    We consider implications of the microscopic dynamics of spacetime for the evolution of cosmological models. We argue that quantum geometry effects may lead to stochastic fluctuations of the gravitational constant, which is thus considered as a macroscopic effective dynamical quantity. Consistency with Riemannian geometry entails the presence of a time-dependent dark energy term in the modified field equations, which can be expressed in terms of the dynamical gravitational constant. We suggest that the late-time accelerated expansion of the Universe may be ascribed to quantum fluctuations in the geometry of spacetime rather than the vacuum energy from the matter sector.

  10. Qubit lattice coherence induced by electromagnetic pulses in superconducting metamaterials.

    PubMed

    Ivić, Z; Lazarides, N; Tsironis, G P

    2016-01-01

    Quantum bits (qubits) are at the heart of quantum information processing schemes. Currently, solid-state qubits, and in particular the superconducting ones, seem to satisfy the requirements for being the building blocks of viable quantum computers, since they exhibit relatively long coherence times, extremely low dissipation, and scalability. The possibility of achieving quantum coherence in macroscopic circuits comprising Josephson junctions, envisioned by Legett in the 1980's, was demonstrated for the first time in a charge qubit; since then, the exploitation of macroscopic quantum effects in low-capacitance Josephson junction circuits allowed for the realization of several kinds of superconducting qubits. Furthermore, coupling between qubits has been successfully achieved that was followed by the construction of multiple-qubit logic gates and the implementation of several algorithms. Here it is demonstrated that induced qubit lattice coherence as well as two remarkable quantum coherent optical phenomena, i.e., self-induced transparency and Dicke-type superradiance, may occur during light-pulse propagation in quantum metamaterials comprising superconducting charge qubits. The generated qubit lattice pulse forms a compound "quantum breather" that propagates in synchrony with the electromagnetic pulse. The experimental confirmation of such effects in superconducting quantum metamaterials may open a new pathway to potentially powerful quantum computing. PMID:27403780

  11. Electromagnetically induced transparency in hybrid plasmonic-dielectric system.

    PubMed

    Tang, Bin; Dai, Lei; Jiang, Chun

    2011-01-17

    We present theoretical and numerical analysis of a plasmonic-dielectric hybrid system for symmetric and asymmetric coupling between silver cut-wire pairs and silicon grating waveguide with periodic grooves. The results show that both couplings can induce electromagnetically-induced transparency (EIT) analogous to the quantum optical phenomenon. The transmission spectrum shows a single transparency window for the symmetric coupling. The strong normal phase dispersion in the vicinity of this transparent window results in the slow light effect. However, the transmission spectrum appears an additional transparency window for asymmetry coupling due to the double EIT effect, which stems from an asymmetrically coupled resonance (ACR) between the dark and bright modes. More importantly, the excitation of ACR is further associated with remarkable improvement of the group index from less than 40 to more than 2500 corresponding to a high transparent efficiency by comparing with the symmetry coupling. This scheme provides an alternative way to develop the building block of systems for plasmonic sensing, all optical switching and slow light applications.

  12. Qubit lattice coherence induced by electromagnetic pulses in superconducting metamaterials

    PubMed Central

    Ivić, Z.; Lazarides, N.; Tsironis, G. P.

    2016-01-01

    Quantum bits (qubits) are at the heart of quantum information processing schemes. Currently, solid-state qubits, and in particular the superconducting ones, seem to satisfy the requirements for being the building blocks of viable quantum computers, since they exhibit relatively long coherence times, extremely low dissipation, and scalability. The possibility of achieving quantum coherence in macroscopic circuits comprising Josephson junctions, envisioned by Legett in the 1980’s, was demonstrated for the first time in a charge qubit; since then, the exploitation of macroscopic quantum effects in low-capacitance Josephson junction circuits allowed for the realization of several kinds of superconducting qubits. Furthermore, coupling between qubits has been successfully achieved that was followed by the construction of multiple-qubit logic gates and the implementation of several algorithms. Here it is demonstrated that induced qubit lattice coherence as well as two remarkable quantum coherent optical phenomena, i.e., self-induced transparency and Dicke-type superradiance, may occur during light-pulse propagation in quantum metamaterials comprising superconducting charge qubits. The generated qubit lattice pulse forms a compound ”quantum breather” that propagates in synchrony with the electromagnetic pulse. The experimental confirmation of such effects in superconducting quantum metamaterials may open a new pathway to potentially powerful quantum computing. PMID:27403780

  13. Qubit lattice coherence induced by electromagnetic pulses in superconducting metamaterials

    NASA Astrophysics Data System (ADS)

    Ivić, Z.; Lazarides, N.; Tsironis, G. P.

    2016-07-01

    Quantum bits (qubits) are at the heart of quantum information processing schemes. Currently, solid-state qubits, and in particular the superconducting ones, seem to satisfy the requirements for being the building blocks of viable quantum computers, since they exhibit relatively long coherence times, extremely low dissipation, and scalability. The possibility of achieving quantum coherence in macroscopic circuits comprising Josephson junctions, envisioned by Legett in the 1980’s, was demonstrated for the first time in a charge qubit; since then, the exploitation of macroscopic quantum effects in low-capacitance Josephson junction circuits allowed for the realization of several kinds of superconducting qubits. Furthermore, coupling between qubits has been successfully achieved that was followed by the construction of multiple-qubit logic gates and the implementation of several algorithms. Here it is demonstrated that induced qubit lattice coherence as well as two remarkable quantum coherent optical phenomena, i.e., self-induced transparency and Dicke-type superradiance, may occur during light-pulse propagation in quantum metamaterials comprising superconducting charge qubits. The generated qubit lattice pulse forms a compound ”quantum breather” that propagates in synchrony with the electromagnetic pulse. The experimental confirmation of such effects in superconducting quantum metamaterials may open a new pathway to potentially powerful quantum computing.

  14. Qubit lattice coherence induced by electromagnetic pulses in superconducting metamaterials.

    PubMed

    Ivić, Z; Lazarides, N; Tsironis, G P

    2016-07-12

    Quantum bits (qubits) are at the heart of quantum information processing schemes. Currently, solid-state qubits, and in particular the superconducting ones, seem to satisfy the requirements for being the building blocks of viable quantum computers, since they exhibit relatively long coherence times, extremely low dissipation, and scalability. The possibility of achieving quantum coherence in macroscopic circuits comprising Josephson junctions, envisioned by Legett in the 1980's, was demonstrated for the first time in a charge qubit; since then, the exploitation of macroscopic quantum effects in low-capacitance Josephson junction circuits allowed for the realization of several kinds of superconducting qubits. Furthermore, coupling between qubits has been successfully achieved that was followed by the construction of multiple-qubit logic gates and the implementation of several algorithms. Here it is demonstrated that induced qubit lattice coherence as well as two remarkable quantum coherent optical phenomena, i.e., self-induced transparency and Dicke-type superradiance, may occur during light-pulse propagation in quantum metamaterials comprising superconducting charge qubits. The generated qubit lattice pulse forms a compound "quantum breather" that propagates in synchrony with the electromagnetic pulse. The experimental confirmation of such effects in superconducting quantum metamaterials may open a new pathway to potentially powerful quantum computing.

  15. Limits on cloud-induced fluctuation in photovoltaic generation

    SciTech Connect

    Jewell, W.T. ); Unruh, T.D. )

    1990-03-01

    When cloud shadows move across a photovoltaic (PV) array, the array's power output is reduced. It resumes full production when the shadow moves away. The utility must follow these changes with other types of generations. Under certain cloud conditions, the changes can be large and fast. A methodology is presented to assess the cost of such fluctuations and their effect on a utility's ability to serve its load. A case study is also presented.

  16. Calibration of Atmospherically Induced Delay Fluctuations Due to Water Vapor

    NASA Technical Reports Server (NTRS)

    Resch, George; Jacobs, Christopher; Keihm, Steve; Lanyi, Gabor; Naudet, Charles; Riley, Abraham; Rosenberger, Hans; Tanner, Alan

    2000-01-01

    We have completed a new generation of water vapor radiometers (WVR), the A- series, in order to support radio science experiments with the Cassini spacecraft. These new instruments sense three frequencies in the vicinity of the 22 GHz emission line of atmospheric water vapor within a 1 degree beamwidth from a clear aperture antenna that is co-pointed with the radio telescope down to 10 degree elevation. The radiometer electronics features almost an order of magnitude improvement in temperature stability compared with earlier WVR designs. For many radio science experiments, the error budget is likely to be dominated by path delay fluctuations due to variable atmospheric water vapor along the line-of-sight to the spacecraft. In order to demonstrate the performance of these new WVRs we are attempting to calibrate the delay fluctuations as seen by a radio interferometer operating over a 21 km baseline with a WVR near each antenna. The characteristics of these new WVRs will be described and the results of our preliminary analysis will be presented indicating an accuracy of 0.2 to 0.5 mm in tracking path delay fluctuations over time scales of 10 to 10,000 seconds.

  17. Rotation shear induced fluctuation decorrelation in a toroidal plasma

    SciTech Connect

    Hahm, T.S.

    1994-06-01

    The enhanced decorrelation of fluctuations by the combined effects of the E {times} B flow (V{sub E}) shear, the parallel flow (V{sub {parallel}}) shear, and the magnetic shear is studied in toroidal geometry. A two-point nonlinear analysis previously utilized in a cylindrical model shows that the reduction of the radial correlation length below its ambient turbulence value ({Delta}r{sub 0}) is characterized by the ratio between the shearing rate {omega}{sub s} and the ambient turbulence scattering rate {Delta}{omega}{sub T}. The derived shearing rate is given by {omega}{sub s}{sup 2} = ({Delta}r{sub 0}){sup 2}[1/{Delta}{phi}{sup 2}{l_brace}{partial_derivative}/{partial_derivative}r(qV{sub E}/r){r_brace}{sup 2} + 1/{Delta}{eta}{sup 2}{l_brace}{partial_derivative}/{partial_derivative}r(V{parallel}/qR){r_brace}{sup 2}], where {Delta}{phi} and {Delta}{eta} are the correlation angles of the ambient turbulence along the toroidal and parallel directions. This result deviates significantly from the cylindrical result for high magnetic shear or for ballooning-like fluctuations. For suppression of flute-like fluctuations, only the radial shear of qV{sub E}/r contributes, and the radial shear of V{parallel}/qR is irrelevant regardless of the plasma rotation direction.

  18. Large cross phase modulation using double electromagnetically induced transparency

    NASA Astrophysics Data System (ADS)

    Wang, Zeng-Bin

    This thesis deals with the engineering of accumulated cross-phase modulation (XPM) cross phase shifts (XPS) between two weak pulses based on large coherent nonlinear interaction enhanced by a medium that exhibits Electromagnetically Induced Transparency (EIT). Applications of such nonlinear phase shifts in optical quantum information processing (OQIP) are also investigated. I present a novel theoretical model to generate large XPM coefficients between two pulses while simultaneously creating Double Electromagnetically Induced Transparency (DEIT) for both signals so that detrimental effects such as absorption and distortion are significantly suppressed, leading to a large accumulated XPM XPS with near-zero absorption. Analytical solutions are derived to demonstrate the dominant physical processes. These solutions are based on analytical methods that use perturbation theory under adiabatic conditions. I also produce accurate solutions by numerically simulating the master equation and the one dimensional paraxial equation. I show how to implement this promising scheme with the D1 line of 87Rb atomic gas by applying a static magnetic field with moderate intensity. This magnetic field perturbs the atom levels according to the nonlinear Zeeman effect and thus the perturbed atomic levels provide the atomic configuration needed for this scheme. A tripod configuration inherent to the D1 line is used to create DEIT for both signals and thus allows one to slow down both signals and to flexibly manipulate the group velocities of both. I numerically simulate the master equation for this 16-level system and find a good agreement with the simplified 5-level N-Tripod system. I also investigate applications of such large XPM in OQIP. As shown in current Controlled-Phase gate (CPHASE gate) proposals based on XPS, the phase shift caused by XPM for pulses having matched group velocities would have a similar profile with the pulse shape of the single-photon pulse, which precludes a

  19. Fluctuation-induced forces in a fluid membrane under tension

    NASA Astrophysics Data System (ADS)

    Zandi, Roya

    2012-02-01

    We develop an exact method to calculate thermal Casimir forces between inclusions of arbitrary shapes and separation, embedded in a fluid membrane whose fluctuations are governed by the combined action of surface tension, bending modulus, and Gaussian rigidity. Each object's shape and mechanical properties enter only through a characteristic matrix, a static analog of the scattering matrix. We calculate the Casimir interaction between two elastic disks embedded in a membrane. In particular, we find that at short separations the interaction is strong and independent of surface tension.

  20. Optimizing Electromagnetically Induced Transparency Signals with Laguerre-Gaussian Beams

    NASA Astrophysics Data System (ADS)

    Holtfrerich, Matthew; Akin, Tom; Krzyzewski, Sean; Marino, Alberto; Abraham, Eric

    2016-05-01

    We have performed electromagnetically induced transparency in ultracold Rubidium atoms using a Laguerre-Gaussian laser mode as the control beam. Laguerre-Gaussian modes are characterized by a ring type transverse intensity profile and carry intrinsic orbital angular momentum. This angular momentum carried by the control beam can be utilized in optical computing applications which is unavailable to the more common Gaussian laser field. Specifically, we use a Laguerre-Gaussian control beam with a Gaussian probe to show that the linewidth of the transmission spectrum can be narrowed when compared to a Gaussian control beam that has the same peak intensity. We present data extending this work to compare control fields in both the Gaussian and Laguerre-Gaussian modes with constant total power. We have made efforts to find the optical overlap that best minimizes the transmission linewidth while also maintaining signal contrast. This was done by changing the waist size of the control beam with respect to the probe. The best results were obtained when the waist of a Laguerre-Gaussian control beam is equal to the waist of the Gaussian probe resulting in narrow linewidth features.

  1. Electromagnetic field generation by ATP-induced reverse electron transfer.

    PubMed

    Steele, Richard H

    2003-03-01

    This paper describes a mechanism to explain low-level light emission in biology. A biological analog of the electrical circuitry, modeled on the parallel plate capacitor, traversed by a helical structure, required to generate electromagnetic radiation in the optical spectral range, is described. The charge carrier required for the emissions is determined to be an accelerating electron driven by an ATP-induced reverse electron transfer. The radial velocity component, the emission trajectory, of the moving charges traversing helical protein structures in a cyclotron-type mechanism is proposed to be imposed by the ferromagnetic field components of the iron in the iron-sulfur proteins. The redox systems NADH, riboflavin, and chlorophyll were examined with their long-wavelength absorption maxima determining the energetic parameters for the calculations. Potentials calculated from the axial velocity components for the riboflavin and NADH systems were found to equal the standard redox potentials of these systems as measured electrochemically and enzymatically. The mechanics for the three systems determined the magnetic moments, the angular momenta, and the orbital magnetic fluxes to be adiabatic invariant parameters. The De Broglie dual wave-particle equation, the fundamental equation of wave mechanics, and the key idea of quantum mechanics, establishes the wavelengths for accelerating electrons which, divided into a given radial velocity, gives its respective emission frequency. Electrons propelled through helical structures, traversed by biologically available electric and magnetic fields, make accessible to the internal environment the optical spectral frequency range that the solar spectrum provides to the external environment.

  2. All-dielectric metasurface analogue of electromagnetically induced transparency.

    PubMed

    Yang, Yuanmu; Kravchenko, Ivan I; Briggs, Dayrl P; Valentine, Jason

    2014-01-01

    Metasurface analogues of electromagnetically induced transparency (EIT) have been a focus of the nanophotonics field in recent years, due to their ability to produce high-quality factor (Q-factor) resonances. Such resonances are expected to be useful for applications such as low-loss slow-light devices and highly sensitive optical sensors. However, ohmic losses limit the achievable Q-factors in conventional plasmonic EIT metasurfaces to values <~10, significantly hampering device performance. Here we experimentally demonstrate a classical analogue of EIT using all-dielectric silicon-based metasurfaces. Due to extremely low absorption loss and coherent interaction of neighbouring meta-atoms, a Q-factor of 483 is observed, leading to a refractive index sensor with a figure-of-merit of 103. Furthermore, we show that the dielectric metasurfaces can be engineered to confine the optical field in either the silicon resonator or the environment, allowing one to tailor light-matter interaction at the nanoscale. PMID:25511508

  3. Polariton states in circuit QED for electromagnetically induced transparency

    NASA Astrophysics Data System (ADS)

    Gu, Xiu; Huai, Sai-Nan; Nori, Franco; Liu, Yu-xi

    2016-06-01

    Electromagnetically induced transparency (EIT) has been extensively studied in various systems. However, it is not easy to observe in superconducting quantum circuits (SQCs) because the Rabi frequency of the strong-controlling field corresponding to EIT is limited by the decay rates of the SQCs. Here, we show that EIT can be achieved by engineering decay rates in a superconducting circuit QED system through a classical driving field on the qubit. Without such a driving field, the dressed states of the system, describing a superconducting qubit coupled to a cavity field, are approximately product states of the cavity and qubit states in the large-detuning regime. However, the driving field can strongly mix these dressed states. These doubly dressed states, here called polariton states, are formed by the driving field and dressed states, and are a mixture of light and matter. The weights of the qubit and cavity field in the polariton states can now be tuned by the driving field, and thus the decay rates of the polariton states can be changed. We choose the three lowest-energy polariton states with a Λ -type transition in such a driven circuit QED system, and demonstrate how EIT and Autler-Townes splitting can be realized in this compound system. We believe that this study will be helpful for EIT experiments using SQCs.

  4. Handedness Dependent Electromagnetically Induced Transparency in Hybrid Chiral Metamaterials

    PubMed Central

    Kang, Lei; Hao Jiang, Zhi; Yue, Taiwei; Werner, Douglas H.

    2015-01-01

    We provide the first experimental demonstration of the handedness dependent electromagnetically induced transparency (EIT) in chiral metamaterials during the interaction with circularly polarized waves. The observed chiral-sensitive EIT phenomena arise from the coherent excitation of a non-radiative mode in the component split ring resonators (SRRs) produced by the corresponding Born−Kuhn type (radiative) resonators that are responsible for the pronounced chirality. The coherent coupling, which is dominated by the bonding and antibonding resonances of the Born−Kuhn type resonators, leads to an extremely steep dispersion for a circularly polarized wave of predefined handedness. Accordingly, retrieved effective medium parameters from simulated results further reveal a difference of 80 in the group indices for left- and right-handed circularly polarized waves at frequencies within the EIT window, which can potentially result in handedness-sensitive pulse delays. These chiral metamaterials which enable a handedness dependent EIT effect may provide more degrees of freedom for designing circular polarization based communication devices. PMID:26183735

  5. Electromagnetically induced transparency resonances inverted in magnetic field

    SciTech Connect

    Sargsyan, A.; Sarkisyan, D. E-mail: david@ipr.sci.am; Pashayan-Leroy, Y.; Leroy, C.; Cartaleva, S.; Wilson-Gordon, A. D.; Auzinsh, M.

    2015-12-15

    The phenomenon of electromagnetically induced transparency (EIT) is investigated in a Λ-system of the {sup 87}Rb D{sub 1} line in an external transverse magnetic field. Two spectroscopic cells having strongly different values of the relaxation rates γ{sub rel} are used: an Rb cell with antirelaxation coating (L ∼ 1 cm) and an Rb nanometric- thin cell (nanocell) with a thickness of the atomic vapor column L = 795 nm. For the EIT in the nanocell, we have the usual EIT resonances characterized by a reduction in the absorption (dark resonance (DR)), whereas for the EIT in the Rb cell with an antirelaxation coating, the resonances demonstrate an increase in the absorption (bright resonances (BR)). We suppose that such an unusual behavior of the EIT resonances (i.e., the reversal of the sign from DR to BR) is caused by the influence of an alignment process. The influence of alignment strongly depends on the configuration of the coupling and probe frequencies as well as on the configuration of the magnetic field.

  6. Electromagnetically induced transparency in rubidium: An advanced undergraduate laboratory

    NASA Astrophysics Data System (ADS)

    Mayer, Shannon; Olson, Abraham

    2008-05-01

    Electromagnetically induced transparency (EIT) can be used to modify the optical response of an atomic medium to a resonant laser field. In EIT, a non-resonant pump laser beam can result in the reduction of absorption of a weak, resonant probe laser beam, provided the fields are coherently coupled by a common state. EIT provides a unique means of coherently controlling photons and has potential applications in fields ranging from quantum computing to telecommunications. In this advanced laboratory we describe the theory and experiment for investigating ladder-type EIT in rubidium gas. The theoretical absorption profile of a weak probe laser beam tuned across the 5S 1/2 to 5P 3/2 transition (780.2 nm) is modeled in the presence of a strong coupling laser beam tuned to the 5P 3/2 to 5D 5/2 transition (776.0 nm) and the absorption transparency window is characterized. Using grating-feedback diode lasers, we observe EIT experimentally in rubidium gas and compare the results to the theoretical model. Applications of EIT to high-resolution two-photon spectroscopy are also discussed. This laboratory uses much of the same equipment as the saturated absorption experiment commonly performed on the D2 line in rubidium, so it is easily implemented in laboratories with the equipment to conduct that experiment.

  7. Electromagnetically induced transparency in rubidium: An advanced undergraduate laboratory

    NASA Astrophysics Data System (ADS)

    Mayer, Shannon; Olson, Abraham

    2008-05-01

    Electromagnetically induced transparency (EIT) is a quantum interference effect used to modify the optical response of an atomic medium to a resonant laser field. In EIT, a non-resonant pump laser beam can result in the reduction of absorption of a weak, resonant probe laser beam, provided the fields are coherently coupled by a common state. EIT provides a unique means of coherently controlling photons and has potential applications in fields ranging from quantum computing to telecommunications. In this advanced laboratory we describe the theory and experiment for investigating ladder-type EIT in rubidium gas. The theoretical absorption profile of a weak probe laser beam tuned across the 5S 1/2 to 5P 3/2 transition (780.2 nm) is modeled in the presence of a strong coupling laser beam tuned to the 5P 3/2 to 5D 5/2 transition (776.0 nm) and the absorption transparency window is characterized. Using grating-feedback diode lasers, we observe EIT experimentally in rubidium gas and compare the results to the theoretical model. Applications of EIT to high-resolution two-photon spectroscopy are also discussed. This laboratory uses much of the same equipment as the saturated absorption experiment commonly performed on the D2 line in rubidium, so it is easily implemented in laboratories with the equipment to conduct that experiment.

  8. Measurements of ICRF wave-induced density fluctuations in LHD by a microwave reflectometer

    NASA Astrophysics Data System (ADS)

    Ejiri, A.; Tokuzawa, T.; Tsujii, N.; Saito, K.; Seki, T.; Kasahara, H.; Kamio, S.; Seki, R.; Mutoh, T.; Yamada, I.; Takase, Y.

    2015-12-01

    An O-mode microwave reflectometer has been developed to measure ICRF wave induced electron density fluctuations in LHD plasmas. The system has two probing frequencies (28.8 and 30.1 GHz) to measure two spatial points simultaneously. The rms density fluctuation levels are typically 0.01%. The linearity between the measured density fluctuation amplitude and the square root of the RF power is discussed. The decay length of the RF field was estimated to be 1 to 7 m under the operational condition investigated. A typical spatial distance between the two measurement points corresponding to the two probing frequencies is a few centimeters, and the fluctuation amplitudes at the two points are similar in amplitude. The phase difference between the two fluctuations show in-phase relationship on average. Out-of phase relationships, which implies a standing wave structure, are often observed when the wave absorption is expected to be poor.

  9. Spectroscopic Observation of Fluctuation-Induced Dynamo in the Edge of the Reversed-Field Pinch

    SciTech Connect

    Fontana, P. W.; Den Hartog, D. J.; Fiksel, G.; Prager, S. C.

    2000-07-17

    The fluctuation-induced dynamo has been investigated by direct measurement of v(tilde sign) and b(tilde sign) in the edge of a reversed-field pinch and is found to be significant in balancing Ohm's law. The velocity fluctuations producing the dynamo emf have poloidal mode number m=0 , consistent with MHD calculations and in contrast with the core m=1 dynamo. The velocity fluctuations exhibit the parity relative to their resonant surface predicted by linear MHD theory. (c) 2000 The American Physical Society.

  10. Vibration-induced field fluctuations in a superconducting magnet

    NASA Astrophysics Data System (ADS)

    Britton, J. W.; Bohnet, J. G.; Sawyer, B. C.; Uys, H.; Biercuk, M. J.; Bollinger, J. J.

    2016-06-01

    Superconducting magnets enable precise control of nuclear and electron spins, and are used in experiments that explore biological and condensed-matter systems, and fundamental atomic particles. In high-precision applications, a common view is that slow (<1 Hz ) drift of the homogeneous magnetic-field limits control and measurement precision. We report on previously undocumented higher-frequency field noise (10-200 Hz) that limits the coherence time of Be+9 electron-spin qubits in the 4.46 -T field of a superconducting magnet. We measure a spin-echo T2 coherence time of ˜6 ms for the Be+9 electron-spin resonance at 124 GHz , limited by part-per-billion fractional fluctuations in the magnet's homogeneous field. Vibration isolation of the magnet improved T2 to ˜50 ms.

  11. Emergent spin electromagnetism induced by magnetization textures in the presence of spin-orbit interaction (invited)

    SciTech Connect

    Tatara, Gen; Nakabayashi, Noriyuki

    2014-05-07

    Emergent electromagnetic field which couples to electron's spin in ferromagnetic metals is theoretically studied. Rashba spin-orbit interaction induces spin electromagnetic field which is in the linear order in gradient of magnetization texture. The Rashba-induced effective electric and magnetic fields satisfy in the absence of spin relaxation the Maxwell's equations as in the charge-based electromagnetism. When spin relaxation is taken into account besides spin dynamics, a monopole current emerges generating spin motive force via the Faraday's induction law. The monopole is expected to play an important role in spin-charge conversion and in the integration of spintronics into electronics.

  12. Vibrational spectra from atomic fluctuations in dynamics simulations. II. Solvent-induced frequency fluctuations at femtosecond time resolution

    NASA Astrophysics Data System (ADS)

    Schmitz, Matthias; Tavan, Paul

    2004-12-01

    The midinfrared (MIR) spectra of molecules in polar solvents exhibit inhomogeneously broadened bands whose spectral positions are shifted as compared to the gas phase. The shifts are caused by interactions with structured solvation shells and the broadenings by fluctuations of these interactions. The MIR spectra can be calculated from hybrid molecular dynamics (MD) simulations, which treat the solute molecule by density functional theory and the solvent by molecular mechanics by the so-called instantaneous normal mode analysis (INMA) or by Fourier transforming the time correlation function (FTTCF) of the molecular dipole moment. In Paper I of this work [M. Schmitz and P. Tavan, J. Chem. Phys. 121, 12233 (2004)] we explored an alternative method based on generalized virial (GV) frequencies noting, however, that GV systematically underestimates frequencies. As shown by us these artifacts are caused by solvent-induced fluctuations of the (i) equilibrium geometry, (ii) force constants, and (iii) normal mode directions as well as by (iv) diagonal and (v) off-diagonal anharmonicities. Here we now show, by analyzing the time scales of fluctuations and sample MD trajectories of formaldehyde in the gas phase and in water, that all these sources of computational artifacts can be made visible by a Fourier analysis of the normal coordinates. Correspondingly, the error sources (i) and (iii)-(v) can be removed by bandpass filtering, as long as the spectral signatures of the respective effects are well separated from the fundamental band. Furthermore, the artifacts arising from effect (ii) can be strongly diminished by a time-resolved version of the GV approach (TF-GV). The TF-GV method then yields for each mode j a trajectory of the vibrational frequency ωj(t|τ) at a time resolution τ>τj, which is only limited by the corresponding oscillation time τj=2π/ωj and, thus, is in the femtosecond range. A correlation analysis of these trajectories clearly separates the

  13. Drift- or fluctuation-induced ordering and self-organization in driven many-particle systems

    NASA Astrophysics Data System (ADS)

    Helbing, D.; Platkowski, T.

    2002-10-01

    According to empirical observations, some pattern formation phenomena in driven many-particle systems are more pronounced in the presence of a certain noise level. We investigate this phenomenon of fluctuation-driven ordering with a cellular-automaton model of interactive motion in space and find an optimal noise strength, while order breaks down at high(er) fluctuation levels. Additionally, we discuss the phenomenon of noise- and drift-induced self-organization in systems that would show disorder in the absence of fluctuations. In the future, related studies may have applications to the control of many-particle systems such as the efficient separation of particles. The rather general formulation of our model in the spirit of game theory may allow to shed some light on several different kinds of noise-induced ordering phenomena observed in physical, chemical, biological, and socio-economic systems (e.g., attractive and repulsive agglomeration, or segregation).

  14. Fluctuating Pressure Environments and Hydrodynamic Radial Force Mitigation for a Two Blade Unshrouded Inducer

    NASA Technical Reports Server (NTRS)

    Mulder, Andrew; Skelley, Stephen

    2011-01-01

    Fluctuating pressure data from water flow testing of an unshrouded two blade inducer revealed a cavitation induced oscillation with the potential to induce a radial load on the turbopump shaft in addition to other more traditionally analyzed radial loads. Subsequent water flow testing of the inducer with a rotating force measurement system confirmed that the cavitation induced oscillation did impart a radial load to the inducer. After quantifying the load in a baseline configuration, two inducer shroud treatments were selected and tested to reduce the cavitation induced load. The first treatment was to increase the tip clearance, and the second was to introduce a circumferential groove near the inducer leading edge. Increasing the clearance resulted in a small load decrease along with some steady performance degradation. The groove greatly reduced the hydrodynamic load with little to no steady performance loss. The groove did however generate some new, relatively high frequency, spatially complex oscillations to the environment.

  15. Fluctuating Pressure Environments and Hydrodynamic Radial Force Mitigation for a Two Blade Unshrouded Inducer

    NASA Technical Reports Server (NTRS)

    Mulder, Andrew; Skelley, Stephen

    2011-01-01

    Fluctuating pressure data from water flow testing of an unshrouded two blade inducer revealed a cavitation induced oscillation with the potential to induce a radial load on the turbopump shaft in addition to other more traditionally analyzed radial loads. Subsequent water flow testing of the inducer with a rotating force measurement system confirmed that the cavitation induced oscillation did impart a radial load to the inducer. After quantifying the load in a baseline configuration, two inducer shroud treatments were selected and tested to reduce the cavitation induced load. The first treatment was to increase the tip clearance, and the second was to introduce a circumferential groove near the inducer leading edge. Increasing the clearance resulted in a small decrease in radial load along with some steady performance degradation. The groove greatly reduced the hydrodynamic load with little to no steady performance loss. The groove did however generate some new, relatively high frequency, spatially complex oscillations to the flow environment.

  16. Spontaneous electromagnetic fluctuations in unmagnetized plasmas. V. Relativistic form factors of weakly damped/amplified thermal modes

    SciTech Connect

    Felten, T.; Schlickeiser, R.

    2013-08-15

    Closed analytical expressions for the spontaneously emitted fluctuation spectra of weakly damped/amplified fluctuations in unmagnetized plasmas are derived using fully relativistic dispersion functions and form factors for the important class of isotropic thermal plasmas. Especially, an electron-proton plasma is investigated in the limits of nonrelativistic and ultrarelativistic plasma temperatures. The results confirm the earlier nonrelativistic approach for positive values of the imaginary frequency γ and complete the nonrelativistic treatment for negative values of γ<0. The well known electrostatic, collective Langmuir mode also occurs within the relativistic theory of spontaneously emitted fluctuations and is analytically and graphically identified. For the first time, the ultrarelativistic temperature limit is analyzed for subluminal phase speeds, which leads to the identification of an additional, so far unknown, longitudinal subluminal collective mode.

  17. Spontaneous electromagnetic fluctuations in unmagnetized plasmas. V. Relativistic form factors of weakly damped/amplified thermal modes

    NASA Astrophysics Data System (ADS)

    Felten, T.; Schlickeiser, R.

    2013-08-01

    Closed analytical expressions for the spontaneously emitted fluctuation spectra of weakly damped/amplified fluctuations in unmagnetized plasmas are derived using fully relativistic dispersion functions and form factors for the important class of isotropic thermal plasmas. Especially, an electron-proton plasma is investigated in the limits of nonrelativistic and ultrarelativistic plasma temperatures. The results confirm the earlier nonrelativistic approach for positive values of the imaginary frequency γ and complete the nonrelativistic treatment for negative values of γ <0. The well known electrostatic, collective Langmuir mode also occurs within the relativistic theory of spontaneously emitted fluctuations and is analytically and graphically identified. For the first time, the ultrarelativistic temperature limit is analyzed for subluminal phase speeds, which leads to the identification of an additional, so far unknown, longitudinal subluminal collective mode.

  18. Fluctuation-induced noise in out-of-equilibrium disordered superconducting films

    NASA Astrophysics Data System (ADS)

    Petković, Aleksandra; Vinokur, Valerii M.

    2013-12-01

    We study out-of-equilibrium transport in disordered superconductors close to the superconducting transition. We consider a thin film connected by resistive tunnel interfaces to thermal reservoirs having different chemical potentials and temperatures. The nonequilibrium longitudinal current-current correlation function is calculated within the nonlinear sigma model description and nonlinear dependence on temperatures and chemical potentials is obtained. Different contributions are calculated, originating from the fluctuation-induced suppression of the quasiparticle density of states, Maki-Thompson and Aslamazov-Larkin processes. As a special case of our results, close-to-equilibrium we obtain the longitudinal ac conductivity using the fluctuation-dissipation theorem.

  19. Nonlinear fluctuations-induced rate equations for linear birth-death processes

    NASA Astrophysics Data System (ADS)

    Honkonen, J.

    2008-05-01

    The Fock-space approach to the solution of master equations for one-step Markov processes is reconsidered. It is shown that in birth-death processes with an absorbing state at the bottom of the occupation-number spectrum and occupation-number independent annihilation probability of occupation-number fluctuations give rise to rate equations drastically different from the polynomial form typical of birth-death processes. The fluctuation-induced rate equations with the characteristic exponential terms are derived for Mikhailov’s ecological model and Lanchester’s model of modern warfare.

  20. Shock induced ignition and DDT in the presence of mechanically driven fluctuations

    NASA Astrophysics Data System (ADS)

    Wang, Wentian; McDonald, James G.; Radulescu, Matei I.

    2015-11-01

    The present study addresses the problem of shock induced ignition and transition to detonation in the presence of mechanical and thermal fluctuations. These departures from a homogeneous medium are of significant importance in practical situations, where such fluctuations may promote hot-spot ignition and favor the flame transition to detonation. The problem is studied in 1D, where a piston-induced shock ignites the gas. The fluctuations in the shock-compressed medium are controlled by allowing the piston's speed to oscillate around a mean, with controllable frequency and amplitude. A Lagrangian numerical formulation is used, which allows to treat exactly the transient boundary condition at the piston head. The hydrodynamic solver is coupled with the reactive dynamics of the gas using Cantera. The code was verified by comparison with steady state ZND solutions and previous shock induced ignition results in homogeneous media. Results obtained for different fuels illustrate the strong relation of the DDT amplification length to mechanical fluctuations in systems with a high effective activation energy and fast rate of energy deposition, consistent with experiments performed on fast flame acceleration in the presence of strong mechanical perturbations. Financial support from NSERC and Shell, with A. Pekalski and M. Levin as technical monitors, are greatly acknowledged.

  1. Tunable electromagnetically induced transparency in coupled three-dimensional split-ring-resonator metamaterials

    PubMed Central

    Han, Song; Cong, Longqing; Lin, Hai; Xiao, Boxun; Yang, Helin; Singh, Ranjan

    2016-01-01

    Metamaterials have recently enabled coupling induced transparency due to interference effects in coupled subwavelength resonators. In this work, we present a three dimensional (3-D) metamaterial design with six-fold rotational symmetry that shows electromagnetically induced transparency with a strong polarization dependence to the incident electromagnetic wave due to the ultra-sharp resonance line width as a result of interaction between the constituent meta-atoms. However, when the six-fold rotationally symmetric unit cell design was re-arranged into a fourfold rotational symmetry, we observed the excitation of a polarization insensitive dual-band transparency. Thus, the 3-D split-ring resonators allow new schemes to observe single and multi-band classical analogues of electromagnetically induced transparencies that has huge potential applications in slowing down light, sensing modalities, and filtering functionalities either in the passive mode or the active mode where such effects could be tuned by integrating materials with dynamic properties. PMID:26857034

  2. Tunable electromagnetically induced transparency in coupled three-dimensional split-ring-resonator metamaterials

    NASA Astrophysics Data System (ADS)

    Han, Song; Cong, Longqing; Lin, Hai; Xiao, Boxun; Yang, Helin; Singh, Ranjan

    2016-02-01

    Metamaterials have recently enabled coupling induced transparency due to interference effects in coupled subwavelength resonators. In this work, we present a three dimensional (3-D) metamaterial design with six-fold rotational symmetry that shows electromagnetically induced transparency with a strong polarization dependence to the incident electromagnetic wave due to the ultra-sharp resonance line width as a result of interaction between the constituent meta-atoms. However, when the six-fold rotationally symmetric unit cell design was re-arranged into a fourfold rotational symmetry, we observed the excitation of a polarization insensitive dual-band transparency. Thus, the 3-D split-ring resonators allow new schemes to observe single and multi-band classical analogues of electromagnetically induced transparencies that has huge potential applications in slowing down light, sensing modalities, and filtering functionalities either in the passive mode or the active mode where such effects could be tuned by integrating materials with dynamic properties.

  3. Fluctuation Induced Structure in Chemical Reaction with Small Number of Molecules

    NASA Astrophysics Data System (ADS)

    Suzuki, Yasuhiro

    We investigate the behaviors of chemical reactions of the Lotka-Volterra model with small number of molecules; hence the occurrence of random fluctuations modifies the deterministic behavior and the law of mass action is replaced by a stochastic model. We model it by using Abstract Rewriting System on Multisets, ARMS; ARMS is a stochastic method of simulating chemical reactions and it is based on the reaction rate equation. We confirmed that the magnitude of fluctuations on periodicity of oscillations becomes large, as the number of involved molecules is getting smaller; and these fluctuations induce another structure, which have not observed in the reactions with large number of molecules. We show that the underling mechanism through investigating the coarse grained phase space of ARMS.

  4. Electromagnetically induced absorption via spontaneously generated coherence of a Λ system

    NASA Astrophysics Data System (ADS)

    Liu, Cheng-pu; Gong, Shang-qing; Fan, Xi-jun; Xu, Zhi-zhan

    2004-02-01

    The effect of spontaneously generated coherence (SGC) on the pump-probe response of a nearly degenerate Λ system is investigated by taking into account the dephasing of the low-frequency coherence. It is found, in the case of small dephasing, that instead of electromagnetically induced transparency (EIT) at resonance, electromagnetically induced absorption (EIA) can occur due to the effect of SGC. We also study the effect of relative phase between the two applied fields and find that EIA and EIT can transform mutually by adjusting the relative phase.

  5. Dimension-sensitive optical responses of electromagnetically induced transparency vapor in a waveguide

    SciTech Connect

    Jian Qishen; He Sailing

    2006-12-15

    A three-level EIT (electromagnetically induced transparency) vapor is used to manipulate the transparency and absorption properties of the probe light in a waveguide. The most remarkable feature of the present scheme is such that the optical responses resulting from both electromagnetically induced transparency and large spontaneous emission enhancement are very sensitive to the frequency detunings of the probe light as well as to the small changes of the waveguide dimension. The potential applications of the dimension- and dispersion-sensitive EIT responses are discussed, and the sensitivity limits of some waveguide-based sensors, including electric absorption modulator, optical switch, wavelength sensor, and sensitive magnetometer, are analyzed.

  6. Electromagnetic Ion Cyclotron Waves in the Helium Branch Induced by Multiple Electromagnetic Ion Cyclotron Triggered Emissions

    NASA Astrophysics Data System (ADS)

    Shoji, M.; Omura, Y.; Grison, B.; Pickett, J. S.; Dandouras, I. S.; Engebretson, M. J.

    2011-12-01

    Electromagnetic ion cyclotron (EMIC) triggered emissions with rising tones between the H+ and He+ cyclotron frequencies were found in the inner magnetosphere by the recent Cluster observations. Another type of EMIC wave with a constant frequency is occasionally observed below the He+ cyclotron frequency after the multiple EMIC triggered emissions. We performed a self-consistent hybrid simulation with a one-dimensional cylindrical magnetic flux model approximating the dipole magnetic field of the Earth's inner magnetosphere. In the presence of energetic protons with a sufficient density and temperature anisotropy, multiple EMIC triggered emissions are reproduced due to the nonlinear wave growth mechanism of rising-tone chorus emissions, and a constant frequency wave in the He+ EMIC branch is subsequently generated. Through interaction with the multiple EMIC rising-tone emissions, the velocity distribution function of the energetic protons is strongly modified. Because of the pitch angle scattering of the protons, the gradient of the distribution in velocity phase space is enhanced along the diffusion curve of the He+ branch wave, resulting in the linear growth of the EMIC wave in the He+ branch.

  7. Cardiac-induced physiologic noise in tissue is a direct observation of cardiac-induced fluctuations.

    PubMed

    Bhattacharyya, Pallab K; Lowe, Mark J

    2004-01-01

    Recent studies have shown that in certain cases, cardiac and respiratory rate fluctuations in BOLD-weighted MRI time courses may be an artifact unique to rapid sampled acquisitions and may not be present in longer repetition-time acquisitions. The implication of this is that, in these cases, cardiac and respiratory rate fluctuations are not aliased into data that undersample these effects and do not affect the resulting time course measurements. In this study, we show that these cases are specific to regions of large cerebrospinal fluid content and are not generally true for gray matter regions of the brain. We demonstrate that in many brain regions of interest, these fluctuations are directly observed as BOLD fluctuations and thus will affect measurements that undersample these effects.

  8. Fluctuation-induced transport of two coupled particles: Effect of the interparticle interaction

    NASA Astrophysics Data System (ADS)

    Makhnovskii, Yurii A.; Rozenbaum, Viktor M.; Sheu, Sheh-Yi; Yang, Dah-Yen; Trakhtenberg, Leonid I.; Lin, Sheng Hsien

    2014-06-01

    We consider a system of two coupled particles fluctuating between two states, with different interparticle interaction potentials and particle friction coefficients. An external action drives the interstate transitions that induces reciprocating motion along the internal coordinate x (the interparticle distance). The system moves unidirectionally due to rectification of the internal motion by asymmetric friction fluctuations and thus operates as a dimeric motor that converts input energy into net movement. We focus on how the law of interaction between the particles affects the dimer transport and, in particular, the role of thermal noise in the motion inducing mechanism. It is argued that if the interaction potential behaves at large distances as xα, depending on the value of the exponent α, the thermal noise plays a constructive (α > 2), neutral (α = 2), or destructive (α < 2) role. In the case of α = 1, corresponding piecewise linear potential profiles, an exact solution is obtained and discussed in detail.

  9. Fluctuation-induced noise in out-of-equilibrium disordered superconducting films

    SciTech Connect

    Petković, Aleksandra; Vinokur, Valerii M.

    2013-12-15

    We study out-of-equilibrium transport in disordered superconductors close to the superconducting transition. We consider a thin film connected by resistive tunnel interfaces to thermal reservoirs having different chemical potentials and temperatures. The nonequilibrium longitudinal current–current correlation function is calculated within the nonlinear sigma model description and nonlinear dependence on temperatures and chemical potentials is obtained. Different contributions are calculated, originating from the fluctuation-induced suppression of the quasiparticle density of states, Maki–Thompson and Aslamazov–Larkin processes. As a special case of our results, close-to-equilibrium we obtain the longitudinal ac conductivity using the fluctuation–dissipation theorem. -- Highlights: •Contributions to the current noise induced by superconducting fluctuations are calculated. •Nonequilibrium physics is studied. •Nonlinear dependence of the noise on temperatures and chemical potentials of the reservoirs is found.

  10. Extremely low frequency electromagnetic fields prevent chemotherapy induced myelotoxicity.

    PubMed

    Rossi, Edoardo; Corsetti, Maria Teresa; Sukkar, Samir; Poggi, Claudio

    2007-01-01

    Side effects of chemo-radiotherapy reduce the quality and also the survivability of patients. The consequent fatigue and infections, related to myelodepression, act to reduce the dose-intensity of the protocol. Late side effects of chemo-radiotherapy include secondary tumours, acute myeloid leukemias and cardiotoxicity. Side effects of chemotherapy are related to oxidative stress produced by the treatment. Oxidative stress also reduces the efficacy of the treatment. Antioxidative treatment with natural (dietetic) or chemical agents has been reported to reduce the toxicity of chemo-radiotherapy and improve the efficacy of treatment. We here report our experience with SEQEX, an electromedical device that generates Extremely Low Frequency ElectroMagnetic Fields (ELF-EMF) to produce endogenic cyclotronic ionic resonance, to reduce myelotoxicity consequent to ABVD protocol in patients with Hodgkin's lymphoma.

  11. Experimental distinction of Autler-Townes splitting from electromagnetically induced transparency using coupled mechanical oscillators system

    PubMed Central

    Liu, Jingliang; Yang, Hujiang; Wang, Chuan; Xu, Kun; Xiao, Jinghua

    2016-01-01

    Here we experimentally demonstrated the electromagnetically induced transparency (EIT) and Autler-Townes splitting (ATS) effects in mechanical coupled pendulums. The analogue of EIT and ATS has been studied in mechanical systems and the intrinsic physics between these two phenomena are also been discussed. Exploiting the Akaike Information Criterion, we discern the ATS effect from EIT effect in our experimental results. PMID:26751738

  12. Experimental distinction of Autler-Townes splitting from electromagnetically induced transparency using coupled mechanical oscillators system

    NASA Astrophysics Data System (ADS)

    Liu, Jingliang; Yang, Hujiang; Wang, Chuan; Xu, Kun; Xiao, Jinghua

    2016-01-01

    Here we experimentally demonstrated the electromagnetically induced transparency (EIT) and Autler-Townes splitting (ATS) effects in mechanical coupled pendulums. The analogue of EIT and ATS has been studied in mechanical systems and the intrinsic physics between these two phenomena are also been discussed. Exploiting the Akaike Information Criterion, we discern the ATS effect from EIT effect in our experimental results.

  13. Zeeman Electromagnetically Induced Transparency with crossed pump and probe beams: Small angle dependence

    NASA Astrophysics Data System (ADS)

    Campbell, Kaleb; Madkhaly, Samaya; de Medeiros, Dillon; Bali, Samir; Macklin Quantum Information Sciences Collaboration

    2016-05-01

    Progress toward undergraduate oriented experiments on image storage in room-temperature atomic vapor using Electromagnetically Induced Transparency is described. Using a scanning longitudinal magnetic field technique we diagnose and suppress stray magnetic fields and polarization impurity. We consider the pump-probe angular dependence of the EIT signal but at much smaller angles of less than a milliradian.

  14. Analytical Solution for Subsurface Gas Flow to a Well Induced by Surface Pressure Fluctuations

    SciTech Connect

    Rossabi, J.

    2001-06-20

    A simple analytical model is presented for predicting subsurface gas flow to a vadose zone well in response to atmospheric pressure fluctuations (barometric pumping). The effective radial permeability (kr) in the vicinity of the well is determined during model calibration using less than two weeks of data. By combining the flow solution with a solution for the vertical gas pressure, only atmospheric pressure data are required to predict the induced flow through a well. The ability to quantitatively predict naturally induced flow in vadose zone wells by simple and inexpensive measurements is invaluable for systems using barometric pumping for remediation.

  15. Analytical solution for subsurface gas flow to a well induced by surface pressure fluctuations.

    PubMed

    Rossabi, Joseph; Falta, Ronald W

    2002-01-01

    A simple analytical model is presented for predicting subsurface gas flow to a vadose-zone well in response to atmospheric pressure fluctuations (barometric pumping). The effective radial permeability (kr) in the vicinity of the well is determined during model calibration using less than two weeks worth of data. By combining the flow solution with a solution for the vertical gas pressure, only atmospheric pressure data are required to predict the induced flow through a well. The ability to quantitatively predict naturally induced flow in vadose-zone wells by simple and inexpensive measurements is invaluable for systems using barometric pumping for remediation. PMID:11798048

  16. Pressure induced by thermal fluctuation of an elastic filament confined within a narrow channel

    NASA Astrophysics Data System (ADS)

    Freund, L. B.

    2016-08-01

    Consider a flexible macro-molecule that is immersed in water at or above room temperature. As a result of thermal motion within the water, the filament is driven to undergo random fluctuations in shape. These fluctuations are a consequence of uncoordinated motion of water molecules. If the range of filament motion is restricted by nearby surfaces, the phenomenon becomes more complex. In this study, it is presumed that the filament is restricted to lie within a plane so that the motion is two dimensional. Furthermore, the range of the planar motion of the filament is confined to the region between inflexible straight boundaries lying in the plane of motion. A result of thermal fluctuation of the filament is that, when in close proximity to a boundary, a normal pressure is induced between the filament and that confining boundary. In the present development, frictional interaction of the filament with either confining boundary is presumed to be negligible. The goal is to determine the dependence of the induced pressure on the separation distance between the confining boundaries in terms of prevailing thermal conditions and physical characteristics of the system.

  17. Infrared Fiber Radiometer For Thermometry In Electromagnetic Induced Therapeutic Healing

    NASA Astrophysics Data System (ADS)

    Katzir, A.; Bowman, F.; Asfour, Y.; Zur, A.; Valeri, C. R.

    1988-06-01

    Hypothermia is a condition which results from prolonged exposure to a cold environment. Rapid and efficient heating is needed to rewarm the patient from 32-35°C to normal body temperature. Hyperthermia in cancer treatment involves heating malignant tumors to 42.5-43.0°C for an extended period (e.g. 30 min.) in an attempt to obtain remission. Microwave or radio frequency heating is often used for rewarming in hypothermia or for temperature elevation in hyperthermia treatment. One severe problem with such heating is the accurate measurement and control of temperature in the presence of a strong electro-magnetic field. For this purpose we have developed a fiberoptic radiometer system which is based on a non-metallic, infrared fiber probe, which can operate either in contact or in non-contact modes. In preliminary investigations the radiometer worked well in a strong microwave or radiofrequency field, with an accuracy of ±0.5°C.

  18. Continuum resonance induced electromagnetic torque by a rotating plasma response to static resonant magnetic perturbation field

    NASA Astrophysics Data System (ADS)

    Liu, Yueqiang; Connor, J. W.; Cowley, S. C.; Ham, C. J.; Hastie, R. J.; Hender, T. C.

    2012-10-01

    A numerical study is carried out, based on a simple toroidal tokamak equilibrium, to demonstrate the radial re-distribution of the electromagnetic torque density, as a result of a rotating resistive plasma (linear) response to a static resonant magnetic perturbation field. The computed electromagnetic torque peaks at several radial locations even in the presence of a single rational surface, due to resonances between the rotating response, in the plasma frame, and both Alfvén and sound continuum waves. These peaks tend to merge together to form a rather global torque distribution, when the plasma resistivity is large. The continuum resonance induced net electromagnetic torque remains finite even in the limit of an ideal plasma.

  19. Changes in Relative Thylakoid Protein Abundance Induced by Fluctuating Light in the Diatom Thalassiosira pseudonana.

    PubMed

    Grouneva, Irina; Muth-Pawlak, Dorota; Battchikova, Natalia; Aro, Eva-Mari

    2016-05-01

    One of the hallmarks of marine diatom biology is their ability to cope with rapid changes in light availability due to mixing of the water column and the lens effect. We investigated how irradiance fluctuations influence the relative abundance of key photosynthetic proteins in the centric diatom Thalassiosira pseudonana by means of mass-spectrometry-based approaches for relative protein quantitation. Most notably, fluctuating-light conditions lead to a substantial overall up-regulation of light-harvesting complex proteins as well as several subunits of photosystems II and I. Despite an initial delay in growth under FL, there were no indications of FL-induced photosynthesis limitation, in contrast to other photosynthetic organisms. Our findings further strengthen the notion that diatoms use a qualitatively different mechanism of photosynthetic regulation in which chloroplast-mitochondria interaction has overtaken crucial regulatory processes of photosynthetic light reactions that are typical for the survival of land plants, green algae, and cyanobacteria. PMID:27025989

  20. Blade Section Design of Marine Propellers with Minimum Cavitation Induced Pressure Fluctuations

    NASA Astrophysics Data System (ADS)

    Zeng, Zhibo; Kuiper, Gert

    2015-12-01

    To minimize cavitation induced pressure fluctuations by marine propellers with minimum efficiency loss, the paper presents a new design and optimization method using a blade section design method. The sheet cavity volume variation on a two-dimensional blade section in quasi-steady condition has been simplified to a relation with only a limited number of non-dimensional parameters. This results in a fast prediction method of the cavity volume of a blade section passing a wake peak, using a pre-calculated database. This makes optimization feasible. The optimization method was applied to the propeller of a container ship. Extensive tests in a towing tank and a cavitation channel validated the reduction of pressure fluctuations: 33% reduction in the first blade frequency amplitude and 18% reduction in the second blade frequency amplitude, with the same open water efficiency.

  1. Fluctuation-induced shear flow and energy transfer in plasma interchange turbulence

    SciTech Connect

    Li, B.; Sun, C. K.; Wang, X. Y.; Zhou, A.; Wang, X. G.; Ernst, D. R.

    2015-11-15

    Fluctuation-induced E × B shear flow and energy transfer for plasma interchange turbulence are examined in a flux-driven system with both closed and open magnetic field lines. The nonlinear evolution of interchange turbulence shows the presence of two confinement regimes characterized by low and high E × B flow shear. In the first regime, the large-scale turbulent convection is dominant and the mean E × B shear flow is at a relatively low level. By increasing the heat flux above a certain threshold, the increased turbulent intensity gives rise to the transfer of energy from fluctuations to mean E × B flows. As a result, a transition to the second regime occurs, in which a strong mean E × B shear flow is generated.

  2. Induced electromagnetic field by seismic waves in Earth's magnetic field

    NASA Astrophysics Data System (ADS)

    Gao, Yongxin; Chen, Xiaofei; Hu, Hengshan; Wen, Jian; Tang, Ji; Fang, Guoqing

    2014-07-01

    Studied in this article are the properties of the electromagnetic (EM) fields generated by an earthquake due to the motional induction effect, which arises from the motion of the conducting crust across the Earth's magnetic field. By solving the governing equations that couple the elastodynamic equations with Maxwell equations, we derive the seismoelectromagnetic wavefields excited by a single-point force and a double-couple source in a full space. Two types of EM disturbances can be generated, i.e., the coseismic EM field accompanying the seismic wave and the independently propagating EM wave which arrives much earlier than the seismic wave. Simulation of an Mw6.1 earthquake shows that at a receiving location where the seismic acceleration is on the order of 0.1 m/s2, the coseismic electric and magnetic fields are on the orders of 1 μV/m and 0.1 nT, respectively, agreeing with the EM data observed in 2008 Mw6.1 Qingchuan earthquake, China, and indicating that the motional induction effect is effective enough to generate observable EM signal. We also simulated the EM signals observed by Haines et al. which were called the Lorentz fields and cannot be explained by the electrokinetic effect. The result shows that the EM wave generated by a horizontal force can explain the data well, suggesting that the motional induction effect is responsible for the Lorentz fields. The motional induction effect is compared with the electrokinetic effect, showing the overall conclusion that the former dominates the mechanoelectric conversion under low-frequency and high-conductivity conditions while the latter dominates under high-frequency and low-conductivity conditions.

  3. Causal signal transmission by quantum fields. VI: The Lorentz condition and Maxwell’s equations for fluctuations of the electromagnetic field

    SciTech Connect

    Plimak, L.I.; Stenholm, S.

    2013-11-15

    The general structure of electromagnetic interactions in the so-called response representation of quantum electrodynamics (QED) is analysed. A formal solution to the general quantum problem of the electromagnetic field interacting with matter is found. Independently, a formal solution to the corresponding problem in classical stochastic electrodynamics (CSED) is constructed. CSED and QED differ only in the replacement of stochastic averages of c-number fields and currents by time-normal averages of the corresponding Heisenberg operators. All relations of QED connecting quantum field to quantum current lack Planck’s constant, and thus coincide with their counterparts in CSED. In Feynman’s terms, one encounters complete disentanglement of the potential and current operators in response picture. Based on this parallelism between QED and CSED, it is natural to expect validity of the Lorentz condition and Maxwell’s equations for the time-normal averages of the potential and current. Things however turn out to be more complicated. Maxwell’s equations under the time-normal ordering can only be demonstrated subject to cancellation of the so-called Schwinger terms by gauge-invariant regularisations. We presume this pattern to be general, formulating this as “commutativity conjecture”. Consistency of the latter with the Heisenberg uncertainty principle is discussed. -- Highlights: •The general structure of interaction in quantum electrodynamics (QED) is analysed. •A detailed parallelism between QED and classical stochastic electrodynamics is shown. •Validity of Maxwell’s equations for fluctuations of the field is discussed. •This validity turns out to be in essence a renormalisation postulate.

  4. Application of strong fluctuation random medium theory to scattering of electromagnetic waves from a half-space of dielectric mixture

    NASA Technical Reports Server (NTRS)

    Tsang, L.; Newton, R. W.; Kong, J. A.

    1982-01-01

    The strong fluctuation random medium theory is applied to calculate scattering from a half-space of dielectric mixture. The first and second moments of the fields are calculated, respectively, by using the bilocal and the distorted Born approximations, and the low frequency limit is taken. The singularity of the dyadic Green's function is taken into account. Expressions for the effective permittivity for the full space case are derived. It is shown that the derived result of the effect permittivity is identical to that of the Polder and van Santern mixing formula. The correlation function of the random medium is obtained by using simple physical arguments and is expressed in terms of the fractional volumes and particle sizes of the constituents of the mixture. Backscattering coefficients of a half-space dielectric mixture are also calculated. Numerical results of the effective permittivity and backscattering coefficients are illustrated using typical parameters encountered in microwave remote sensing of dry and wet snow. It is also shown that experimental data can be matched with the theory by using physical parameters of the medium as obtained from ground truth measurements.

  5. Geometry-induced modification of fluctuation spectrum in quasi-two-dimensional condensates

    NASA Astrophysics Data System (ADS)

    Roy, Arko; Angom, D.

    2016-08-01

    We report the structural transformation of the low-lying spectral modes, especially the Kohn mode, from radial to circular topology as harmonic confining potential is modified to a toroidal one, and this corresponds to a transition from simply to multiply connected geometry. For this we employ the Hartree–Fock–Bogoliubov theory to examine the evolution of low energy quasiparticles. We, then, use the Hartree–Fock–Bogoliubov theory with the Popov approximation to demonstrate the two striking features of quantum and thermal fluctuations. At T = 0, the non-condensate density due to interaction induced quantum fluctuations increases with the transformation from pancake to toroidal geometry. The other feature is, there is a marked change in the density profile of the non-condensate density at finite temperatures with the modification of trapping potential. In particular, the condensate and non-condensate density distributions have overlapping maxima in the toroidal condensate, which is in stark contrast to the case of pancake geometry. The genesis of this difference lies in the nature of the thermal fluctuations.

  6. Turbulence-induced pressure fluctuations in snow and their effect on heat and moisture transport

    NASA Astrophysics Data System (ADS)

    Huwald, H.; Higgins, C. W.; Drake, S.; Nolin, A. W.; Parlange, M. B.

    2010-12-01

    Accurate measurement of the heat and moisture flux components of the energy budget of a snow pack is difficult, and to date no generally satisfying solutions exist. In particular, little quantitative knowledge exists on heat and water vapor exchange associated to dynamically driven air movement in the snow pack as a consequence of atmospheric turbulence. This so-called wind-pumping constitutes a mechanism for forced release of saturated air form the snow pack and thus determines evaporation or sublimation rates from the snow and consequently affects the turbulent latent heat flux. A unique experiment and measurement system has been developed and deployed in the field to investigate and quantify the influence of atmospheric turbulence on heat and moisture transport across the snow-air interface. To this end, high-frequency measurements of 3-dimensional wind components, air temperature, and water vapor fluctuations above the snow surface were taken simultaneously together with differential air pressure fluctuations at several depths in the snow pack. The analysis addresses changes in frequency, amplitude, and penetration depth of the pressure fluctuations with depth, and the relationship of turbulence intensity to attenuation characteristics of the pressure within the snow pack. Finally, the study aims at understanding how turbulence-induced air pressure dynamics within the snow pack impacts on the heat budget of the snow pack and the turbulent sensible and latent heat flux above the snow surface.

  7. Electron fluctuation induced resonance broadening in nano electromechanical systems: the origin of shear force in vacuum.

    PubMed

    Siria, A; Barois, T; Vilella, K; Perisanu, S; Ayari, A; Guillot, D; Purcell, S T; Poncharal, P

    2012-07-11

    This article presents a study of the poorly understood "shear-force" used in an important class of near-field instruments that use mechanical resonance feedback detection. In the case of a metallic probe near a metallic surface in vacuum, we show that in the 10-60 nm range there is no such a thing as a shear-force in the sense of the nonconservative friction force. Fluctuations of the oscillator resonance frequency, likely induced by local charge variations, could account for the reported effects in the literature without introducing a dissipative force.

  8. Electromagnetically induced photonic bandgap in hot Cs atoms

    SciTech Connect

    Li, D. W.; Zhang, L.; Su, X. M.; Zhuo, Z. C.; Kim, J. B

    2010-04-15

    Three-level {Lambda}-type thermal Cs atoms are used to demonstrate the phenomenon of a photonic bandgap induced by quantum coherence with a standing wave (SW). We observed the transmitted signals of probe field driven by several kinds of SW, which are formed by a strong forward-traveling field and a backward-traveling field when a mirror reflects the forward-traveling beam. Considering Doppler inhomogeneous broadenings with a SW drive, we employ Fourier transformation to solve density-matrix equations for simulation results. The simulation results are found to be consistent with the experimental results.

  9. Low-loss metamaterial electromagnetically induced transparency based on electric toroidal dipolar response

    SciTech Connect

    Li, Hai-ming; Liu, Shao-bin Liu, Si-yuan; Ding, Guo-wen; Yang, Hua; Yu, Zhi-yang; Zhang, Hai-feng; Wang, Shen-yun

    2015-02-23

    In this paper, a low-loss and high transmission analogy of electromagnetically induced transparency based on electric toroidal dipolar response is numerically and experimentally demonstrated. It is obtained by the excitation of the low-loss electric toroidal dipolar response, which confines the magnetic field inside a dielectric substrate with toroidal geometry. The metamaterial electromagnetically induced transparency (EIT) structure is composed of the cut wire and asymmetric split-ring resonators. The transmission level is as high as 0.88, and the radiation loss is greatly suppressed, which can be proved by the surface currents distributions, the magnetic field distributions, and the imaginary parts of the effective permeability and permittivity. It offers an effective way to produce low-loss and high transmission metamaterial EIT.

  10. Reconfigurable designs for electromagnetically induced transparency in solid state plasma metamaterials with multiple transmission windows

    NASA Astrophysics Data System (ADS)

    Kong, Xiang-Kun; Mo, Jin-Jun; Yu, Zhi-Yang; Shi, Wei; Li, Hai-Ming; Bian, Bo-Rui

    2016-05-01

    A reconfigurable metamaterial analog electromagnetically-induced-transparency-like (EIT-like) effect is theoretically and numerically demonstrated in this paper. The unit cell is composed of a stimulated circular loop element and an unstimulated arc slot element, which are both constructed by semiconductor. The interaction between the two elements of the unit cell leads to a transparency window, resembling a special quantum optical phenomenon as electromagnetic (EM) induced transparency. The proposed designs can realize a continuously tunable EIT-like effect in a broad frequency range from 2.2 GHz to 3.6 GHz by changing the arc slot angle, while the number of EIT-like transmission windows can be configured by increasing the number of arc slots. This scheme which is constructed by solid state plasma (SSP) metamaterial provides an alternative way to realize the tunable plasmonic sensing and make new kinds of reconfigurable devices.

  11. Evaluating effects of wind-induced pressure fluctuations on soil-atmosphere gas exchange at a landfill using stochastic modelling.

    PubMed

    Poulsen, Tjalfe G; Møldrup, Per

    2006-10-01

    The impact of wind turbulence-induced pressure fluctuations at the soil surface on landfill gas transport and emissions to the atmosphere at an old Danish landfill site was investigated using stochastic modelling combined with soil property and gas transport data measured at the site. The impacts of soil physical properties (including air permeability and volumetric water content) and wind-induced pressure fluctuation properties (amplitude and temporal correlation) on landfill gas emissions to the atmosphere were evaluated. Soil-air permeability and pressure fluctuation amplitude were found to be the most important parameters. Wind-induced gas emissions were further compared with gas emissions caused by diffusion and by long-term pressure variations (due to passing weather systems). Here diffusion and wind-induced gas transport were found to be equally important with wind-induced gas transport becoming the most important at lower soil-air contents.

  12. Recent topics on single-molecule fluctuation analysis using blinking in surface-enhanced resonance Raman scattering: clarification by the electromagnetic mechanism.

    PubMed

    Itoh, Tamitake; Yamamoto, Yuko S

    2016-08-15

    Surface-enhanced Raman scattering (SERS) spectroscopy has become an ultrasensitive tool for clarifying molecular functions on plasmonic metal nanoparticles (NPs). SERS has been used for in situ probing of detailed behaviors of few or single molecules (SMs) at plasmonic NP junctions. SM SERS signals are commonly observed with temporal and spectral changes known as "blinking", which are related to various physical and chemical interactions between molecules and NP junctions. These temporal and spectral changes simultaneously take place, therefore resulting in serious complexities in interpretations of the SM SERS results. Dual contributions of Raman enhancement mechanisms in SERS (i.e., electromagnetic (EM) and chemical enhancements) also make interpretations more difficult. To resolve these issues and reduce the degree of complexities in SM SERS analyses, the present review is focused on the recent studies of probing SM behaviors using SERS exclusively within the framework of the EM mechanism. The EM mechanism is briefly introduced, and several recent topics on SM SERS blinking analysis are discussed in light of the EM mechanism. This review will provide a basis for clarification of complex SERS fluctuations of various molecules.

  13. Nanometer-scale elongation rate fluctuations in the Myriophyllum aquaticum (Parrot feather) stem were altered by radio-frequency electromagnetic radiation.

    PubMed

    Senavirathna, Mudalige Don Hiranya Jayasanka; Asaeda, Takashi; Thilakarathne, Bodhipaksha Lalith Sanjaya; Kadono, Hirofumi

    2014-01-01

    The emission of radio-frequency electromagnetic radiation (EMR) by various wireless communication base stations has increased in recent years. While there is wide concern about the effects of EMR on humans and animals, the influence of EMR on plants is not well understood. In this study, we investigated the effect of EMR on the growth dynamics of Myriophyllum aquaticum (Parrot feather) by measuring the nanometric elongation rate fluctuation (NERF) using a statistical interferometry technique. Plants were exposed to 2 GHz EMR at a maximum of 1.42 Wm(-2) for 1 h. After continuous exposure to EMR, M. aquaticum plants exhibited a statistically significant 51 ± 16% reduction in NERF standard deviation. Temperature observations revealed that EMR exposure did not cause dielectric heating of the plants. Therefore, the reduced NERF was due to a non-thermal effect caused by EMR exposure. The alteration in NERF continued for at least 2.5 h after EMR exposure and no significant recovery was found in post-EMR NERF during the experimental period.

  14. Nanometer-scale elongation rate fluctuations in the Myriophyllum aquaticum (Parrot feather) stem were altered by radio-frequency electromagnetic radiation

    PubMed Central

    Senavirathna, Mudalige Don Hiranya Jayasanka; Asaeda, Takashi; Thilakarathne, Bodhipaksha Lalith Sanjaya; Kadono, Hirofumi

    2014-01-01

    The emission of radio-frequency electromagnetic radiation (EMR) by various wireless communication base stations has increased in recent years. While there is wide concern about the effects of EMR on humans and animals, the influence of EMR on plants is not well understood. In this study, we investigated the effect of EMR on the growth dynamics of Myriophyllum aquaticum (Parrot feather) by measuring the nanometric elongation rate fluctuation (NERF) using a statistical interferometry technique. Plants were exposed to 2 GHz EMR at a maximum of 1.42 Wm−2 for 1 h. After continuous exposure to EMR, M. aquaticum plants exhibited a statistically significant 51 ± 16% reduction in NERF standard deviation. Temperature observations revealed that EMR exposure did not cause dielectric heating of the plants. Therefore, the reduced NERF was due to a non-thermal effect caused by EMR exposure. The alteration in NERF continued for at least 2.5 h after EMR exposure and no significant recovery was found in post-EMR NERF during the experimental period. PMID:24670369

  15. Controlling the spectrum of light pulses by dynamical electromagnetically induced transparency

    SciTech Connect

    Ignesti, Emilio; Sali, Emiliano; Tognetti, Marco V.; Buffa, Roberto; Fini, Lorenzo; Cavalieri, Stefano

    2011-05-15

    We present a theoretical and experimental study on the possibility of spectral manipulation of weak probe-laser pulses in the presence of dynamical electromagnetically induced transparency. We predict a spectral enlargement or narrowing process depending on whether the probe-laser pulse is overlapped by the rising or the falling edge of the coupling pulse, respectively. The results of an experiment in sodium atomic vapors confirm the theoretical predictions.

  16. Four-wave mixing in a three-level bichromatic electromagnetically induced transparency system

    SciTech Connect

    Yang, G. Q.; Xu, P.; Wang, J.; Zhan, M. S.; Zhu Yifu

    2010-10-15

    We investigate the four-wave mixing (FWM) phenomenon in a three-level bichromatic electromagnetically induced transparency system. Theoretical results predict that the FWM will exhibit a multipeak structure under bichromatic coupling fields. The stronger the coupling fields are, the more FWM the peaks should exhibit. Results of an experiment carried out with cold {sup 87}Rb atoms in a magneto-optical trap agree with the theoretical prediction.

  17. Electromagnetically induced transparency in an open {Lambda}-type molecular lithium system

    SciTech Connect

    Lazoudis, A.; Kirova, T.; Ahmed, E. H.; Lyyra, A. M.; Li, L.; Qi, J.

    2010-08-15

    We present an experimental study of electromagnetically induced transparency (EIT) in a {Lambda}-type molecular lithium system. Copropagating beam geometry is utilized in order to minimize the residual Doppler width. A coupling laser power dependent study of the EIT feature is carried out. Our findings have been complemented by theoretical studies of open systems that trace the presence of EIT starting from the density-matrix equations. Numerical simulations have been performed and are in good agreement with the experimental results.

  18. Electromagnetically induced transparency in Rb-filled coated hollow-core photonic crystal fiber.

    PubMed

    Light, P S; Benabid, F; Couny, F; Maric, M; Luiten, A N

    2007-05-15

    We report the observation of lambda-configuration electromagnetically induced transparency as well as optical pumping in rubidium-filled kagome-structure hollow-coated-core photonic crystal fiber. We show that a polydimethylsiloxane coating of the fiber core reduces the linewidth of the transparency below that which could be expected for an uncoated fiber. The measured 6 MHz linewidth was dominated by optical broadening.

  19. Electromagnetically induced transparency in Rb-filled coated hollow-core photonic crystal fiber

    NASA Astrophysics Data System (ADS)

    Light, P. S.; Benabid, F.; Couny, F.; Maric, M.; Luiten, A. N.

    2007-05-01

    We report the observation of lambda-configuration electromagnetically induced transparency as well as optical pumping in rubidium-filled kagome-structure hollow-coated-core photonic crystal fiber. We show that a polydimethylsiloxane coating of the fiber core reduces the linewidth of the transparency below that which could be expected for an uncoated fiber. The measured 6 MHz linewidth was dominated by optical broadening.

  20. Hanle electromagnetically induced transparency and absorption resonances with a Laguerre Gaussian beam

    SciTech Connect

    Anupriya, J.; Ram, Nibedita; Pattabiraman, M.

    2010-04-15

    We describe a computational and experimental study on Hanle electromagnetically induced transparency and absorption resonance line shapes with a Laguerre Gaussian (LG) beam. It is seen that the LG beam profile brings about a significant narrowing in the line shape of the Hanle resonance and ground-state Zeeman coherence in comparison to a Gaussian beam. This narrowing is attributed to the azimuthal mode index of the LG field.

  1. Numerical simulation of adiabatons in electromagnetically induced transparency under quasi-resonance conditions

    SciTech Connect

    Parshkov, O M; Govorenko, E R

    2014-02-28

    The evolution of adiabatons in electromagnetically induced transparency in the Λ scheme of degenerate quantum transitions J = 0 → J = 1 → J = 2 with Doppler broadening of spectral lines has been numerically simulated taking into account the effect of resonance detunings. It is shown that, in the case of linearly polarised fields, an increase in the probe-field resonance detuning (under exact-resonance conditions for the control radiation) leads to a transformation of electromagnetically induced transparency into electromagnetically induced absorption at certain stages. When the control-field resonance detuning is varied, the transparency of the medium for the probe (exactly resonant) radiation monotonically decreases with increasing detuning because of the rising role of single-photon absorption. In the case of circularly polarised control radiation and linearly polarised input probe field, a probe pulse propagating in the medium splits into two pulses with oppositely directed circular polarisations. An increase in the probe pulse resonance detuning (under exact-resonance conditions for the control radiation) leads primarily to an increase in the absorption by the medium of the probe pulse, the direction of circular polarisation for which coincides with the circular-polarisation direction for the control radiation. (nonlinear optical phenomena)

  2. Electromagnetically induced transparency in rubidium vapor prepared by a comb of short optical pulses

    SciTech Connect

    Sautenkov, Vladimir A.; Rostovtsev, Yuri V.; Ye, C.Y.; Welch, George R.; Kocharovskaya, Olga; Scully, Marlan O.

    2005-06-15

    It was shown by Kocharovskaya and Khanin [Sov. Phys. JETP 63, 945 (1986)] that a comb of optical pulses can induce a ground-state atomic coherence and change the optical response of an atomic medium. In our experiment, we studied the propagation of a comb of optical pulses produced by a mode-locked diode laser in rubidium atomic vapor. Electromagnetically induced transparency (EIT) was observed when the pulse repetition rate is a subharmonic of the hyperfine splitting of the ground state. The width of the EIT resonance is determined by the relaxation rate of the ground-state coherence. Possible applications to magnetometery, atomic clocks, and frequency chains are discussed.

  3. Plasmonic analog of electromagnetically-induced transparency of asymmetrical slots waveguide

    NASA Astrophysics Data System (ADS)

    Sun, Lin; Wang, Jicheng; Hu, Zheng-Da; Wang, Xiaosai; Chen, Jing

    2016-02-01

    In this paper, electromagnetically-induced transparency (EIT) phenomena have been investigated numerically in the plasmonic waveguides composed of unsymmetrical slot shaped metal-insulator-metal (MIM) structures. By the transmission line theory and Fabry-Perot model, the formation and evolution mechanisms of plasmon-induced transparency were exactly analyzed. The analysis showed that the peak of EIT-like transmission could be changed easily according to certain rules by adjusting the geometrical parameters of the slot structures, including the coupling distances and slot depths. We can find a new method to design nanoscale optical switch, devices in optical storage and optical computing.

  4. Electromagnetic field redistribution induced selective plasmon driven surface catalysis in metal nanowire-film systems.

    PubMed

    Pan, Liang; Huang, Yingzhou; Yang, Yanna; Xiong, Wen; Chen, Guo; Su, Xun; Wei, Hua; Wang, Shuxia; Wen, Weijia

    2015-01-01

    For the novel interpretation of Raman spectrum from molecule at metal surface, the plasmon driven surface catalysis (PDSC) reactions have become an interesting topic in the research field of surface enhanced Raman scattering (SERS). In this work, the selective PDSC reactions of p,p'-dimercaptoazobenzene (DMAB) produced from para-aminothiophenol (PATP) or 4-nitrobenzenethiol (4NBT) were demonstrated in the Ag nanowires dimer-Au film systems. The different SERS spectra collected at individual part and adjacent part of the same nanowire-film system pointed out the importance of the electromagnetic field redistribution induced by image charge on film in this selective surface catalysis, which was confirmed by the simulated electromagnetic simulated electro- magnetic field distributions. Our result indicated this electromagnetic field redistribution induced selective surface catalysis was largely affected by the polarization and wavelength of incident light but slightly by the difference in diameters between two nanowires. Our work provides a further understanding of PDSC reaction in metal nanostructure and could be a deep support for the researches on surface catalysis and surface analysis.

  5. Electromagnetic field redistribution induced selective plasmon driven surface catalysis in metal nanowire-film systems

    PubMed Central

    Pan, Liang; Huang, Yingzhou; Yang, Yanna; Xiong, Wen; Chen, Guo; Su, Xun; Wei, Hua; Wang, Shuxia; Wen, Weijia

    2015-01-01

    For the novel interpretation of Raman spectrum from molecule at metal surface, the plasmon driven surface catalysis (PDSC) reactions have become an interesting topic in the research field of surface enhanced Raman scattering (SERS). In this work, the selective PDSC reactions of p,p’-dimercaptoazobenzene (DMAB) produced from para-aminothiophenol (PATP) or 4-nitrobenzenethiol (4NBT) were demonstrated in the Ag nanowires dimer-Au film systems. The different SERS spectra collected at individual part and adjacent part of the same nanowire-film system pointed out the importance of the electromagnetic field redistribution induced by image charge on film in this selective surface catalysis, which was confirmed by the simulated electromagnetic simulated electro- magnetic field distributions. Our result indicated this electromagnetic field redistribution induced selective surface catalysis was largely affected by the polarization and wavelength of incident light but slightly by the difference in diameters between two nanowires. Our work provides a further understanding of PDSC reaction in metal nanostructure and could be a deep support for the researches on surface catalysis and surface analysis. PMID:26601698

  6. Fluctuations in central and peripheral temperatures induced by intravenous nicotine: central and peripheral contributions.

    PubMed

    Tang, Jeremy S; Kiyatkin, Eugene A

    2011-04-01

    Nicotine (NIC) is a highly addictive substance that interacts with different subtypes of nicotinic acetylcholine receptors widely distributed in the central and peripheral nervous systems. While the direct action of NIC on central neurons appears to be essential for its reinforcing properties, the role of peripheral actions of this drug remains a matter of controversy. In this study, we examined changes in locomotor activity and temperature fluctuations in the brain (nucleus accumbens and ventral tegmental area), temporal muscle, and skin induced by intravenous (iv) NIC at low human-relevant doses (10 and 30μg/kg) in freely moving rats. These effects were compared to those induced by social interaction, an arousing procedure that induces behavioral activation and temperature responses via pure neural mechanisms, and iv injections of a peripherally acting NIC analog, NIC pyrrolidine methiodide (NIC-PM) used at equimolar doses. We found that NIC at 30μg/kg induces a modest locomotor activation, rapid and strong decrease in skin temperature, and weak increases in brain and muscle temperature. While these effects were qualitatively similar to those induced by social interaction, they were much weaker and showed a tendency to increase with repeated drug administrations. In contrast, NIC-PM did not affect locomotion and induced much weaker than NIC increases in brain and muscle temperatures and decreases in skin temperature; these effects showed a tendency to be weaker with repeated drug administrations. Our data indicate that NIC's actions in the brain are essential to induce locomotor activation and brain and body hyperthermic responses. However, rapid peripheral action of NIC on sensory afferents could be an important factor in triggering its central effects, contributing to neural and physiological activation following repeated drug use. PMID:21295014

  7. Theoretical and experimental study of electromagnetic forces induced in one-dimensional photonic crystals

    NASA Astrophysics Data System (ADS)

    Lugo, J. E.; Doti, Rafael; Faubert, Jocelyn; Sanchez, Noemi; Sanchez, Javier; Palomino, Martha A.; de la Mora, M. Beatriz; del Rio, J. Antonio

    2013-10-01

    We studied theoretically and experimentally the induction of electromagnetic forces in one-dimensional photonic crystals with localized defects when light impinges transversally to the defect layer. The theoretical calculations indicate that the electromagnetic forces increases at a certain frequency that coincide with a defect photonic state. The photonic structure consists of a microcavity like structure formed of two one-dimensional photonic crystals made of free-standing porous silicon, separated by variable air gap and the working wavelength is 633 nm. The force generation is made evident by driving a laser light by means of a chopper; the light hits the photonic structure and induces a vibration and the vibration is characterized by using a very sensitive vibrometer.

  8. Electromagnetically superconducting phase of QCD vacuum induced by strong magnetic field

    SciTech Connect

    Chernodub, M. N.

    2011-05-23

    In this talk we discuss our recent suggestion that the QCD vacuum in a sufficiently strong magnetic field (stronger than 10{sup 16} Tesla) may undergo a spontaneous transition to an electromagnetically superconducting state. The possible superconducting state is anisotropic (the vacuum exhibits superconductivity only along the axis of the uniform magnetic field) and inhomogeneous (in the transverse directions the vacuum structure shares similarity with the Abrikosov lattice of an ordinary type-II superconductor). The electromagnetic superconductivity of the QCD vacuum is suggested to occur due to emergence of specific quark-antiquark condensates which carry quantum numbers of electrically charged rho mesons. A Lorentz-covariant generalization of the London transport equations for the magnetic-field-induced superconductivity is given.

  9. Induced chirality through electromagnetic coupling between chiral molecular layers and plasmonic nanostructures.

    PubMed

    Abdulrahman, Nadia A; Fan, Z; Tonooka, Taishi; Kelly, Sharon M; Gadegaard, Nikolaj; Hendry, Euan; Govorov, Alexander O; Kadodwala, Malcolm

    2012-02-01

    We report a new approach for creating chiral plasmonic nanomaterials. A previously unconsidered, far-field mechanism is utilized which enables chirality to be conveyed from a surrounding chiral molecular material to a plasmonic resonance of an achiral metallic nanostructure. Our observations break a currently held preconception that optical properties of plasmonic particles can most effectively be manipulated by molecular materials through near-field effects. We show that far-field electromagnetic coupling between a localized plasmon of a nonchiral nanostructure and a surrounding chiral molecular layer can induce plasmonic chirality much more effectively (by a factor of 10(3)) than previously reported near-field phenomena. We gain insight into the mechanism by comparing our experimental results to a simple electromagnetic model which incorporates a plasmonic object coupled with a chiral molecular medium. Our work offers a new direction for the creation of hybrid molecular plasmonic nanomaterials that display significant chiroptical properties in the visible spectral region.

  10. Quantum random walks in a coherent atomic system via electromagnetically induced transparency

    SciTech Connect

    Li Yun; Hang Chao; Ma Lei; Zhang Weiping; Huang Guoxiang

    2008-12-15

    We propose a scheme to realize the quantum random walk in a coherent five-level atomic system via electromagnetically induced transparency (EIT). From optical Bloch equations describing the dynamics of the electromagnetic field and atomic population and coherence, we show that two circular-polarized components of a probe field display different dispersion properties and hence acquire different phase-shift modifications when passing through atomic cells. We demonstrate that the quantum coherence and interference owing to the EIT effect result in a low absorption of the probe field and hence provide a possibility of realizing a many-step phase-shift quantum random walk. The scheme may be used to experimentally highlight the characteristics of quantum random walk and lead to a promising application for quantum computation.

  11. Classical analogue of electromagnetically induced transparency with a metal-superconductor hybrid metamaterial.

    PubMed

    Kurter, Cihan; Tassin, Philippe; Zhang, Lei; Koschny, Thomas; Zhuravel, Alexander P; Ustinov, Alexey V; Anlage, Steven M; Soukoulis, Costas M

    2011-07-22

    Metamaterials are engineered materials composed of small electrical circuits producing novel interactions with electromagnetic waves. Recently, a new class of metamaterials has been created to mimic the behavior of media displaying electromagnetically induced transparency (EIT). Here we introduce a planar EIT metamaterial that creates a very large loss contrast between the dark and radiative resonators by employing a superconducting Nb film in the dark element and a normal-metal Au film in the radiative element. Below the critical temperature of Nb, the resistance contrast opens up a transparency window along with a large enhancement in group delay, enabling a significant slowdown of waves. We further demonstrate precise control of the EIT response through changes in the superfluid density. Such tunable metamaterials may be useful for telecommunication because of their large delay-bandwidth products.

  12. Investigation of the static and dynamic fragmentation of metallic liquid sheets induced by random surface fluctuations

    NASA Astrophysics Data System (ADS)

    Durand, O.; Soulard, L.; Bourasseau, E.; Filippini, G.

    2016-07-01

    We perform molecular dynamics simulations to investigate the static and dynamic fragmentation of metallic liquid sheets of tin induced by random surface fluctuations. The static regime is analyzed by simulating sheets of different thicknesses, and the dynamic fragmentation is ensured by applying along the longitudinal direction of a sheet an instantaneous expansion velocity per initial unit length (expansion rate) with values ranging from 1 × 109 to 3 × 1010 s-1. The simulations show that the static/dynamic fragmentation becomes possible when the fluctuations of the upper and lower surfaces of the sheets can either overlap or make the local volume density of the system go down below a critical value. These two mechanisms cause locally in the sheet the random nucleation of pores of void, on a timescale that exponentially increases with the sheet thickness. Afterwards, the pores develop following distinct stages of growth, coalescence, and percolation, and later in time aggregates of liquid metal are formed. The simulations also show that the fragmentation of static sheets is characterized by relatively mono-dispersed surface and volume distributions of the pores and aggregates, respectively, whereas in extreme conditions of dynamic fragmentation (expansion rate typically in the range of 1 × 1010 s-1), the distributions are rather poly-dispersed and obey a power law decay with surface (volume). A model derived from the simulations suggests that both dynamic and static regimes of fragmentation are similar for expansion rates below typically 1 × 107 s-1.

  13. Solvent induced conformational fluctuation of alanine dipeptide studied by using vibrational probes.

    PubMed

    Cai, Kaicong; Du, Fenfen; Liu, Jia; Su, Tingting

    2015-02-25

    The solvation effect on the three dimensional structure and the vibrational feature of alanine dipeptide (ALAD) was evaluated by applying the implicit solvents from polarizable continuum solvent model (PCM) through ab initio calculations, by using molecular dynamic (MD) simulations with explicit solvents, and by combining these two approaches. The implicit solvent induced potential energy fluctuations of ALAD in CHCl3, DMSO and H2O are revealed by means of ab initio calculations, and a global view of conformational and solvation environmental dependence of amide I frequencies is achieved. The results from MD simulations with explicit solvents show that ALAD trends to form PPII, αL, αR, and C5 in water, PPII and C5 in DMSO, and C5 in CHCl3, ordered by population, and the demonstration of the solvated structure, the solute-solvent interaction and hydrogen bonding is therefore enhanced. Representative ALAD-solvent clusters were sampled from MD trajectories and undergone ab initio calculations. The explicit solvents reveal the hydrogen bonding between ALAD and solvents, and the correlation between amide I frequencies and the CO bond length is built. The implicit solvents applied to the ALAD-solvent clusters further compensate the solvation effect from the bulk, and thus enlarge the degree of structural distortion and the amide I frequency red shift. The combination of explicit solvent in the first hydration shell and implicit solvent in the bulk is helpful for our understanding about the conformational fluctuation of solvated polypeptides through vibrational probes.

  14. Direction reversal of fluctuation-induced biased Brownian motion on distorted ratchets.

    PubMed

    Yan, B; Miura, R M; Chen, Y D

    2001-05-21

    The biased movement of Brownian particles on a fluctuating two-state periodic potential made of identical distorted ratchets is studied. The purpose is to investigate how the direction of the particle movement is related to the asymmetry of the potential. In general, distorting one of the two linear arms of a regular symmetric ratchet (with equal arm lengths) can create a driving force for the Brownian particle to execute biased movement. The direction of the induced biased movement depends on the type of the distortion. It has been found that if one linear arm is kinked into two linear sub-arms, the direction of the movement can be either positive or negative depending on the frequency of the fluctuation and the location and the degree of the kink. In contrast, if one arm of the symmetric ratchet is replaced by a continuous nonlinear sinusoidal function, the movement is always unidirectional. Thus, for the latter case to generate the direction reversal phenomenon, the ratchets have to have an additional asymmetry. We also have found that two potentials with different distorted ratchets can generate identical fluxes if the distortions are polar symmetric about the mid-point of the arm(s) of the basic linear two-arm ratchet. The results are useful for designing experimental apparatuses for the separation of protein particles based on their sizes and charges and the viscosity of the medium.

  15. Distortion of Induced Magnetic Fields on the Nightside of the Moon and Implications for Electromagnetic Sounding

    NASA Astrophysics Data System (ADS)

    Fuqua, H.; Fatemi, S.; Delory, G. T.; Poppe, A. R.; De Pater, I.; Grimm, R. E.

    2015-12-01

    Nightside Time Domain Electromagnetic Sounding was performed during the Apollo era using transient discontinuities within the Interplanetary Magnetic Field (IMF) occurring when the Lunar Surface Magnetometer was well within the wake cavity. This analysis assumes that induced fields, generated by conducting layers within the interior of the Moon, respond as an undisturbed spherically symmetric dipole in vacuum. In actuality, the magnetohydrodynamic plasma environment interacts with the induced field. On the dayside, the induced field is confined to the surface by the dynamic pressure of the solar wind. On the nightside, Apollo era theories predicted the induced field would expand into the diamagnetic wake cavity. We present the first hybrid model studying the interaction of the wake fields with an induced dipole field at the Moon. Contrary to the assumptions during the Apollo soundings, we have found that the nightside dipole fields at the Moon are not confined within the wake cavity. The induced fields penetrate out of the rarefraction regions of the wake boundary. Furthermore, within the deep wake, near-vacuum region, distortion of the induced dipole fields due to the interaction with the wake varies between a few percent to more than 15% at the surface depending on the magnitude of the induced field, the geometry of the upstream fields, and the upstream plasma parameters. Thus, our results indicate that under cer tain conditions the assumption of a vacuum dipolar response is reasonable. For the application of this method, a two point measurement is required with altitudes below approximately 400km. Future Electromagnetic Sounding of the interior structure of the Moon with ARTEMIS will provide further insights into the lunar interior structure. These results are applicable to any airless body with a conducting interior, interacting directly with the solar wind in the absence of a parent body magnetic field.

  16. Glassiness and exotic entropy scaling induced by quantum fluctuations in a disorder-free frustrated magnet

    PubMed Central

    Klich, I.; Lee, S.-H.; Iida, K.

    2014-01-01

    When spins are arranged in a lattice of triangular motif, the phenomenon of frustration leads to numerous energetically equivalent ground states, and results in exotic states such as spin liquid and spin ice. Here we report an alternative situation: a system, classically a liquid, freezes in the clean limit into a glassy state induced by quantum fluctuations. We call such glassy state a spin jam. The case in point is a frustrated magnet, where spins are arranged in a triangular network of bipyramids. Quantum corrections break the classical degeneracy into a set of aperiodic spin configurations forming local minima in a rugged energy landscape. This is established by mapping the problem into tiling with hexagonal tiles. The number of tessellations scales with the boundary length rather than its volume, showing the absence of local zero-energy modes. Low-temperature thermodynamics is discussed to compare it with other glassy materials. PMID:24686398

  17. Observation of fluctuation-induced tunneling conduction in micrometer-sized tunnel junctions

    NASA Astrophysics Data System (ADS)

    Lai, Yu-Ren; Yu, Kai-Fu; Lin, Yong-Han; Wu, Jong-Ching; Lin, Juhn-Jong

    2012-09-01

    Micrometer-sized Al/AlOx/Y tunnel junctions were fabricated by the electron-beam lithography technique. The thin (≈ 1.5-2 nm thickness) insulating AlOx layer was grown on top of the Al base electrode by O2 glow discharge. The zero-bias conductances G(T) and the current-voltage characteristics of the junctions were measured in a wide temperature range 1.5-300 K. In addition to the direct tunneling conduction mechanism observed in low-G junctions, high-G junctions reveal a distinct charge transport process which manifests the thermally fluctuation-induced tunneling conduction (FITC) through short nanoconstrictions. We ascribe the experimental realization of the FITC mechanism to originating from the formations of "hot spots" (incomplete pinholes) in the AlOx layer owing to large junction-barrier interfacial roughness.

  18. Scattering-induced changes in the degree of polarization of a stochastic electromagnetic plane-wave pulse.

    PubMed

    Ding, Chaoliang; Cai, Yangjian; Zhang, Yongtao; Pan, Liuzhan

    2012-06-01

    The scattering of a stochastic electromagnetic plane-wave pulse on a deterministic spherical medium is investigated. An analytical formula for the degree of polarization (DOP) of the scattered field in the far zone is derived. Letting pulse duration T(0) → ∞, our formula can be applied to study the scattering of a stationary stochastic electromagnetic light wave. Numerical results show that the DOP of the far zone field is closely determined by the size of the spherical medium when the incident field is a stochastic electromagnetic plane-wave pulse. This is much different from the case when the incident field is a stationary stochastic electromagnetic light wave, where the DOP of the far zone field is independent of the size of the medium. One may obtain the information of the spherical medium by measuring the scattering-induced changes in the DOP of a stochastic electromagnetic plane-wave pulse.

  19. Generation of terahertz radiation via an electromagnetically induced transparency at ion acoustic frequency region in laser-produced dense plasmas.

    PubMed

    Nakagawa, Makoto; Kodama, Ryosuke; Higashiguchi, Takeshi; Yugami, Noboru

    2009-08-01

    Electromagnetically induced transparency is a well-known quantum phenomena that electromagnetic wave controls the refractive index of medium. It enables us to create a passband for low-frequency electromagnetic wave in a dense plasma even if the plasma is opaque for the electromagnetic wave. This technique can be used to prove the ion acoustic wave because the ion acoustic frequency is lower than the plasma frequency. We have investigated a feasibility of electromagnetic radiation at THz region corresponding to the ion acoustic frequency from a dense plasma. We confirmed that the passband is created at about 7.5 THz corresponding to the ion acoustic frequency in the electron plasma density of 10(21) cm(-3) with a Ti:Sapphire laser with the wavelength of 800 nm and the laser intensity of 10(17) W/cm(2). The estimated radiation power is around 1 MW, which is expected to be useful for nonlinear THz science and applications.

  20. Two experimental tests of a fluctuation-induced first-order phase transition: intensity fluctuation microscopy at the nematic-smectic-A transition.

    PubMed

    Yethiraj, Anand; Mukhopadhyay, Ranjan; Bechhoefer, John

    2002-02-01

    We have developed a new, extremely sensitive real-space technique (intensity fluctuation microscopy) to probe the order of the nematic-smectic-A (NA) transition. Using this technique, we show that the NA transition in 4'-n-octyl-4-cyanobiphenyl (8CB) is clearly first order, contrary to calorimetric studies but in agreement with conclusions drawn from front-velocity measurements. We characterize the strength of the discontinuity at the first-order transition by the dimensionless quantity t(0)=(T(NA)-T*)/T(*). By precisely measuring t(0), we have made the first detailed tests of predictions based on the Halperin-Lubensky-Ma (HLM) theory of fluctuation-induced, first-order phase transitions. First, we explore the effect of an external magnetic field on the NA transition. Although modest fields (of order 10 T) are predicted to drive the weakly first-order transition in pure 8CB second order, we observe no such effect; we establish instead that the lower bound on this critical field is approximately 30 T. Likewise, we observe no effect in mixtures of 8CB with its longer chemical homolog 4'-n-decyl-4-cyanobiphenyl (10CB). Second, we examine the dependence of t(0) as a function of 8CB-10CB mixture concentration and find that the data in mixtures with small nematic temperature range are well-fit by the parameters derived by Anisimov et al. based on calorimetric measurements. As we increase the nematic range (by using concentrations closer to pure 8CB), the measured t(0) deviates more and more from the HLM predictions. Smectic fluctuations, which are neglected in the HLM calculation, are an obvious candidate to explain such a discrepancy, but one's naive expectation is that they would reduce t(0) below the HLM levels, whereas the observed values are too large. However, a recent renormalization-group calculation concludes that smectic fluctuations, surprisingly, should indeed increase t(0), explaining the observations presented here.

  1. Quantum Mechanical Enhancement of the Random Dopant Induced Threshold Voltage Fluctuations and Lowering in Sub 0.1 Micron MOSFETs

    NASA Technical Reports Server (NTRS)

    Asenov, Asen; Slavcheva, G.; Brown, A. R.; Davies, J. H.; Saini, Subhash

    1999-01-01

    A detailed study of the influence of quantum effects in the inversion layer on the random dopant induced threshold voltage fluctuations and lowering in sub 0.1 micron MOSFETs has been performed. This has been achieved using a full 3D implementation of the density gradient (DG) formalism incorporated in our previously published 3D 'atomistic' simulation approach. This results in a consistent, fully 3D, quantum mechanical picture which implies not only the vertical inversion layer quantisation but also the lateral confinement effects manifested by current filamentation in the 'valleys' of the random potential fluctuations. We have shown that the net result of including quantum mechanical effects, while considering statistical fluctuations, is an increase in both threshold voltage fluctuations and lowering.

  2. Simulation of electromagnetically and magnetically induced transparency in a magnetized plasma

    NASA Astrophysics Data System (ADS)

    Hur, M. S.; Wurtele, J. S.; Shvets, G.

    2003-07-01

    Electromagnetically induced transparency (EIT), a phenomenon well known in atomic systems, has a natural analogy in a classical magnetized plasma. The magnetized plasma has a resonance for right-hand polarized electromagnetic waves at the electron cyclotron frequency Ω0, so that a probe wave with frequency ω1=Ω0 cannot propagate through the plasma. The plasma can be made transparent to such a probe by the presence of a pump wave. The pump may be an electromagnetic wave or magnetostatic wiggler. Simulations and theory show that the physical reason for the transparency is that the beating of the probe wave with the pump wave sets up a plasma oscillation, and the upper sideband of the pump wave cancels the resonant plasma current due to the probe. The theory of plasma EIT derived here extends that found in the earlier work to include the effects of the lower sideband of the pump and renormalization of the plasma frequency and an analysis of the transient response. A detailed comparison of theory to one-dimensional particle-in-cell simulations is presented and estimates for the performance ion accelerator using the EIT interaction are given. The dispersion relation and estimates for the phase velocity and amplitude of the plasma wave are in good agreement with particle-in-cell simulations.

  3. Microwave tunneling in heterostructures with electromagnetically induced transparency-like metamaterials based on solid state plasma

    NASA Astrophysics Data System (ADS)

    Kong, Xiang-kun; Li, Hai-ming; Bian, Bo-rui; Xue, Feng; Ding, Guo-wen; Yu, Shao-jie; Liu, Si-yuan

    2016-06-01

    Interference induced electromagnetic induced transparency (EIT)-like effect has demonstrated the ability to realize narrow transmission resonances within the single-resonator stop band. Due to the limited plasma density in actual devices, only few reports discuss the plasma metamaterials and truncated photonic crystals which support electromagnetically induced transparency. However, solid state plasma realized by some semiconductors have the advantages of higher order plasma density and the characteristics of the reconfiguration and tunability. Here, we conduct a numerical study of the perfect microwave tunneling in heterostructures composed of solid state plasma metamaterials and truncated photonic crystal. There is particular emphasis on the tunability of tunneling frequency by changing plasma frequency in solid state plasma, as well as the electric energy density distributions in heterostructures. It was found that, compared to conventional metal photonic crystal, the reflectance of tunneling mode can be reduced from -25.8 dB to -41.7 dB with an optimized Q-factor. Further study on electric energy density distribution confirms that EM wave in-plane localization originated from the EIT-like solid state plasma, which gives rise to the three-dimensional enhancement of sub-wavelength EM wave localization, is stronger than EM wave confinement along the propagation direction. Owing to the tunability of plasma, the tunneling frequency channel can be adjusted or reconfigured in a certain range without adjusting the geometry of the heterostructure. It suggests the fabrication for highly sensitive dielectric sensing, optical switches, and so on.

  4. Rayleigh-Taylor-Induced Electromagnetic Fields in Laser-Produced Plasmas

    NASA Astrophysics Data System (ADS)

    Manuel, Mario J.-E.

    Spontaneous electromagnetic fields can be important to the dynamic evolution of a plasma by directing heat flow as well as providing additional pressures on the conducting fluids through the Lorentz force. Electromagnetic fields are predicted to affect fluid behavior during the core-collapse of supernovae through generation of fields due to hydrodynamic instabilities. In the coronae of stars, self-generated magnetic fields lead to filamentary structure in the hot plasma. Recent experiments by Gregori et al. investigated sources of protogalactic magnetic fields generated by laser-produced shock waves. In inertial confinement fusion experiments, self-generated electromagnetic fields can also play a role and have recently become of great interest to the community. Present day laser facilities provide a unique opportunity to study spontaneous field-generation in these extreme environments under controlled conditions. Instability-induced electromagnetic fields were investigated using a novel monoenergetic-proton radiography system. Fusion protons generated by an 'exploding-pusher' implosion were used to probe laser-irradiated plastic foils with various preimposed surface perturbations. Imaging protons are sensitive to electromagnetic fields and density modulations in the plasma through the Lorentz force and Coulomb collisions, respectively. Corresponding x-ray radiographs of these targets provided mass density distributions and Coulomb effects on protons were assessed using a Monte Carlo code written using the Geant4 framework. Proton fluence distributions were recorded on CR-39 detectors and Fourier analyzed to infer path-integrated field strengths. Rayleigh-Taylor (RT) growth of preimposed surface perturbations generated magnetic fields by the RT-induced Biermann battery and were measured for the first time. Good data were obtained during linear growth and when compared to ideal calculations, demonstrated that field diffusion near the source played an important role

  5. Photon wave-packet manipulation via dynamic electromagnetically induced transparency in multilayer structures

    SciTech Connect

    Bariani, Francesco; Carusotto, Iacopo

    2010-01-15

    We present a theoretical study of the dynamics of a light pulse propagating through a multilayer system consisting of alternating blocks of electromagnetically induced transparency (EIT) media and vacuum. We study the effect of a dynamical modulation of the EIT control field on the shape of the wave packet. Interesting effects due to the group velocity mismatch at the interfaces are found. Modulation schemes that can be realized in ultracold atomic samples with standard experimental techniques are proposed and discussed. Calculations are performed using a modified slowly varying envelope approximation of the Maxwell-Bloch equations and are compared to an effective description based on a continuity equation for the polariton flow.

  6. Multi-normal mode-splitting for an optical cavity with electromagnetically induced transparency medium.

    PubMed

    Yu, Xudong; Zhang, Jing

    2010-03-01

    We theoretically study the cavity transmission spectra with three-level atoms coupled by a coherent external control field in the superstrong coupling regime (atoms-cavity coupling strength g [square root] N is near or larger than the cavity free-spectral range DeltaFSR). When satisfying the superstrong coupling condition by increasing the number of the interaction atoms, more than one FSR cavity modes interact with atoms and each mode will split three peaks, which can be well explained by the linear dispersion enhancement of electromagnetically induced transparency medium due to the largely increased atomic density in the cavity.

  7. Theoretical study on electromagnetically induced transparency in molecular aggregate models using quantum Liouville equation method

    SciTech Connect

    Minami, Takuya; Nakano, Masayoshi

    2015-01-22

    Electromagnetically induced transparency (EIT), which is known as an efficient control method of optical absorption property, is investigated using the polarizability spectra and population dynamics obtained by solving the quantum Liouville equation. In order to clarify the intermolecular interaction effect on EIT, we examine several molecular aggregate models composed of three-state monomers with the dipole-dipole coupling. On the basis of the present results, we discuss the applicability of EIT in molecular aggregate systems to a new type of optical switch.

  8. Quantum theory for pulse propagation in electromagnetically-induced-transparency media beyond the adiabatic approximation

    NASA Astrophysics Data System (ADS)

    Chuang, You-Lin; Yu, Ite A.; Lee, Ray-Kuang

    2015-06-01

    Beyond the adiabatic approximation, we develop a quantum theory for optical probe pulses propagating in electromagnetically-induced-transparency (EIT) media by including Langevin noise operators and asking the field operator to satisfy bosonic commutation relation. Influences on the degradation of quantum noise squeezing from optical depth of atomic ensemble, strength of control field, and ground-state decoherence are studied in the slow light, as well as storage and retrieval, for a squeezed probe pulse. Moreover, to give guidelines for realization of quantum interfaces based on EIT media, we demonstrate that the quantum squeezing of output probe pulses could be preserved with a stronger classical control field.

  9. Electromagnetically-induced transparency in Cs and Rb in the same vapor cell

    NASA Astrophysics Data System (ADS)

    Simons, Matt; Gordon, Joshua; Holloway, Christopher

    2016-05-01

    We demonstrate simultaneous electromagnetically-induced transparency (EIT) in both cesium and rubidium in the same vapor cell with coincident optical fields. Each atomic system can detect radio frequency (RF) field strengths through modification of the EIT signal. We show that these two systems can detect the same RF field strength simultaneously. This allows us to perform the same measurement in two effective ``laboratories,'' providing an immediate independent reference, which will lead to an SI-traceable RF E-field measurement. We examine the impact of coincident, simultaneous EIT on RF field metrology and the EIT signal.

  10. Comparison of electromagnetically induced transparency between silver, gold, and aluminum metamaterials at visible wavelengths.

    PubMed

    Hokari, Ryohei; Kanamori, Yoshiaki; Hane, Kazuhiro

    2014-02-10

    Electromagnetically induced transparency (EIT)-like effects in silver, gold, and aluminum metamaterials consisting of dipole resonators and quadrupole resonators were demonstrated at visible wavelengths. Optical characteristics of the metamaterials could be controlled by the gap distance between the two resonators. EIT-like effects were observed at wavelengths between 603 and 789 nm, 654 and 834 nm, and 462 and 693 nm for the silver, gold, and aluminum EIT metamaterials, respectively. At wavelengths longer than around 650 nm, the silver metamaterials had better EIT-like features. At wavelengths shorter than around 650 nm, on the other hand, the aluminum metamaterials showed promising EIT-like results.

  11. Observation of quantum interference between dressed states in an electromagnetically induced transparency

    NASA Astrophysics Data System (ADS)

    Li, Yong-Qing; Xiao, Min

    1995-06-01

    We report on an experimental observation of quantum interference between two dressed states created by a coherent pumping laser in an electromagnetically induced transparency. In a Λ-type three-level atomic system in rubidium vapor, we reduce the Rabi frequency of the pumping laser in one arm down below the spontaneous decay rate of the common excited state and still observe a narrow dip with subnatural linewidth in the absorption curve of a probe beam in another arm. This clearly demonstrates that the absorption reduction at the low pumping intensity is mainly due to the interference between the two dressed states, not due to the ac-Stark-shift effect.

  12. Fracture induced electromagnetic emissions: extending laboratory findings by observations at the geophysical scale

    NASA Astrophysics Data System (ADS)

    Potirakis, Stelios M.; Contoyiannis, Yiannis; Kopanas, John; Kalimeris, Anastasios; Antonopoulos, George; Peratzakis, Athanasios; Eftaxias, Konstantinos; Nomicos, Constantinos

    2014-05-01

    Under natural conditions, it is practically impossible to install an experimental network on the geophysical scale using the same instrumentations as in laboratory experiments for understanding, through the states of stress and strain and their time variation, the laws that govern the friction during the last stages of EQ generation, or to monitor (much less to control) the principal characteristics of a fracture process. Fracture-induced electromagnetic emissions (EME) in a wide range of frequency bands are sensitive to the micro-structural chances. Thus, their study constitutes a nondestructive method for the monitoring of the evolution of damage process at the laboratory scale. It has been suggested that fracture induced MHz-kHz electromagnetic (EM) emissions, which emerge from a few days up to a few hours before the main seismic shock occurrence permit a real time monitoring of the damage process during the last stages of earthquake preparation, as it happens at the laboratory scale. Since the EME are produced both in the case of the laboratory scale fracture and the EQ preparation process (geophysical scale fracture) they should present similar characteristics in these two scales. Therefore, both the laboratory experimenting scientists and the experimental scientists studying the pre-earthquake EME could benefit from each- other's results. Importantly, it is noted that when studying the fracture process by means of laboratory experiments, the fault growth process normally occurs violently in a fraction of a second. However, a major difference between the laboratory and natural processes is the order-of-magnitude differences in scale (in space and time), allowing the possibility of experimental observation at the geophysical scale for a range of physical processes which are not observable at the laboratory scale. Therefore, the study of fracture-induced EME is expected to reveal more information, especially for the last stages of the fracture process, when it

  13. Observation of Doppler-free electromagnetically induced transparency in atoms selected optically with specific velocity

    SciTech Connect

    Yu, Hoon; Kim, Kwan Su; Kim, Jung Dong; Lee, Hyun Kyung; Kim, Jung Bog

    2011-11-15

    We observed an electromagnetically induced transparency signal in a four-level system with optically selected rubidium atoms at specific velocities in a room-temperature vaporized cell. Since the atoms behave like cold atoms in the selected atomic view, the observed signals coincide with a trapped atomic system. According to this result, we can observe Doppler-free signals, which correspond from 1.2 to 1.0 K in a Doppler-broadened medium. And the selected atoms have velocity components of {+-}(131 {+-} 3) MHz per wave number. Our experimental results can provide insight for research in cold media.

  14. Atom-membrane cooling and entanglement using cavity electromagnetically induced transparency

    SciTech Connect

    Genes, Claudiu; Ritsch, Helmut; Drewsen, Michael; Dantan, Aurelien

    2011-11-15

    We investigate a hybrid optomechanical system composed of a micromechanical oscillator as a movable membrane and an atomic three-level ensemble within an optical cavity. We show that a suitably tailored cavity field response via electromagnetically induced transparency (EIT) in the atomic medium allows for strong coupling of the membrane's mechanical oscillations to the collective atomic ground-state spin. This facilitates ground-state cooling of the membrane motion, quantum state mapping, and robust atom-membrane entanglement even for cavity widths larger than the mechanical resonance frequency.

  15. Scalable network of quadrangle entanglements via multiple phase-dependent electromagnetically induced transparency

    SciTech Connect

    Hu Xiangming; Sun Hong; Wang Fei

    2010-10-15

    One important class of multipartite continuous variable entanglement is described by a closed polygon, where every vertex represents one optical field and every side corresponds to the entanglement between the two connected vertices. Here we show that it is possible to obtain a scalable network of quadrangle entanglements by using multiple phase-dependent electromagnetically induced transparency. For 4,6,8,...,2n (n{>=}2) mode cases the network consists of 1,9,36,...,(1/4)n{sup 2} (n-1){sup 2} quadrangles, respectively. This suggests an efficient way of creating complex quantum networks and has great potentials for quantum information and computation.

  16. Electromagnetically induced transparency in terahertz plasmonic metamaterials via dual excitation pathways of the dark mode

    NASA Astrophysics Data System (ADS)

    Liu, Xiaojun; Gu, Jianqiang; Singh, Ranjan; Ma, Yingfang; Zhu, Jun; Tian, Zhen; He, Mingxia; Han, Jiaguang; Zhang, Weili

    2012-03-01

    We observe the excitation and tuning of electromagnetically induced transparency (EIT) by the interference between different excitation pathways of the dark mode in a planar terahertz metamaterial. The EIT unit cell consists of a cut wire as the bright resonator and a pair of split ring resonators (SRRs) as the dark element. The dark mode resonance is excited by both the electric and magnetic fields when the SRR pair translates along the wire without altering the lateral distance between the resonators. The electric and magnetic pathways of exciting the dark mode allows for a giant amplitude modulation of the EIT resonance.

  17. Correlation spectroscopy in cold atoms: Light sideband resonances in electromagnetically-induced-transparency condition

    NASA Astrophysics Data System (ADS)

    Florez, H. M.; Kumar, A.; Theophilo, K.; Nussenzveig, P.; Martinelli, M.

    2016-07-01

    The correlation spectroscopy has been successfully employed in the measurement of the intrinsic linewidth of electromagnetically induced transparency (EIT) in time and frequency domain. We study the role of the sidebands of the intense fields in the measured spectra, analyzing the information that can be recovered working with different analysis frequencies. In this case, the nonzero one-photon detuning appears as a necessary condition for spectrally resolving the sideband resonances in the correlation coefficient. Our experimental findings are supported by the perturbative model defined in the frequency domain.

  18. Coherent perfect absorption in an electromagnetically induced transparency-like (EIT-like) system

    NASA Astrophysics Data System (ADS)

    Zhu, Lei; Guo, Jing; Dong, Liang; Meng, Fan-Yi; Wu, Qun

    2016-09-01

    We propose a scheme for realizing the coherent perfect absorption (CPA) by exploiting the moderate coupling between the electric and magnetic resonators in an electromagnetically induced transparency-like (EIT-like) system. Moreover, the ideal parity-time (PT) symmetry can be established in such a passive system by precisely engineering the rate between the scattering and dissipative losses of resonators as well as their coupling. Specifically, by controlling the phase difference between two incident waves, the absorption ratio of CPA at the peak frequency can be dynamically modulated from 1 to 0. Such a scheme provides an effective route to construct absorbing devices.

  19. A stable frequency comb directly referenced to rubidium electromagnetically induced transparency and two-photon transitions

    SciTech Connect

    Hou, Dong; Wu, Jiutao; Zhang, Shuangyou; Ren, Quansheng; Zhang, Zhigang; Zhao, Jianye

    2014-03-17

    We demonstrate an approach to create a stable erbium-fiber-based frequency comb at communication band by directly locking the combs to two rubidium atomic transitions resonances (electromagnetically induced transparency absorption and two-photon absorption), respectively. This approach directly transfers the precision and stability of the atomic transitions to the comb. With its distinguishing feature of compactness by removing the conventional octave-spanning spectrum and f-to-2f beating facilities and the ability to directly control the comb's frequency at the atomic transition frequency, this stable optical comb can be widely used in optical communication, frequency standard, and optical spectroscopy and microscopy.

  20. Birefringence lens effects of an atom ensemble enhanced by an electromagnetically induced transparency

    SciTech Connect

    Zhang, H. R.; Sun, C. P.; Zhou Lan

    2009-07-15

    We study the optical control for birefringence of a polarized light by an atomic ensemble with a tripod configuration, which is mediated by the electromagnetically induced transparency with a spatially inhomogeneous laser. The atomic ensemble splits the linearly polarized light ray into two orthogonally polarized components, whose polarizations depend on quantum superposition of the initial states of the atomic ensemble. Accompanied with this splitting, the atomic ensemble behaves as a birefringent lens, which allows one polarized light ray passing through straightly while focuses the other light of vertical polarization with finite aberration of focus.

  1. Analogue of electromagnetically induced transparency in integrated plasmonics with radiative and subradiant resonators.

    PubMed

    Wang, Ting; Zhang, Yusheng; Hong, Zhi; Han, Zhanghua

    2014-09-01

    We propose the use of radiative and subradiant resonators coupled to a metal-insulator-metal waveguide to represent the three-level energy diagram in conventional atomic systems and demonstrate a new realization of on-chip plasmonic analogue of electromagnetically-induced transparency (EIT) in integrated plasmonics. The radiative resonator is achieved with the help of aperture-coupling while evanescent coupling is relied for the subradiant resonator. Numerical simulation results demonstrate well-pronounced intermediate transmission peak through the bus waveguide and also show that the EIT effect can be easily controlled by the relative position of the two Fabry-Perot resonators.

  2. A method for detection of muon induced electromagnetic showers with the ANTARES detector

    NASA Astrophysics Data System (ADS)

    Aguilar, J. A.; Al Samarai, I.; Albert, A.; André, M.; Anghinolfi, M.; Anton, G.; Anvar, S.; Ardid, M.; Assis Jesus, A. C.; Astraatmadja, T.; Aubert, J. J.; Baret, B.; Basa, S.; Bertin, V.; Biagi, S.; Bigi, A.; Bigongiari, C.; Bogazzi, C.; Bou-Cabo, M.; Bouhou, B.; Bouwhuis, M. C.; Brunner, J.; Busto, J.; Camarena, F.; Capone, A.; Cârloganu, C.; Carminati, G.; Carr, J.; Cecchini, S.; Charif, Z.; Charvis, P.; Chiarusi, T.; Circella, M.; Coniglione, R.; Costantini, H.; Coyle, P.; Curtil, C.; Decowski, M. P.; Dekeyser, I.; Deschamps, A.; Distefano, C.; Donzaud, C.; Dornic, D.; Dorosti, Q.; Drouhin, D.; Eberl, T.; Emanuele, U.; Enzenhöfer, A.; Ernenwein, J. P.; Escoffier, S.; Fermani, P.; Ferri, M.; Flaminio, V.; Folger, F.; Fritsch, U.; Fuda, J. L.; Galatà, S.; Gay, P.; Giacomelli, G.; Giordano, V.; Gómez-González, J. P.; Graf, K.; Guillard, G.; Halladjian, G.; Hallewell, G.; van Haren, H.; Hartman, J.; Heijboer, A. J.; Hello, Y.; Hernández-Rey, J. J.; Herold, B.; Hößl, J.; Hsu, C. C.; de Jong, M.; Kadler, M.; Kalekin, O.; Kappes, A.; Katz, U.; Kavatsyuk, O.; Kooijman, P.; Kopper, C.; Kouchner, A.; Kreykenbohm, I.; Kulikovskiy, V.; Lahmann, R.; Lamare, P.; Larosa, G.; Lattuada, D.; Lefèvre, D.; Lim, G.; Lo Presti, D.; Loehner, H.; Loucatos, S.; Mangano, S.; Marcelin, M.; Margiotta, A.; Martinez-Mora, J. A.; Meli, A.; Montaruli, T.; Moscoso, L.; Motz, H.; Neff, M.; Nezri, E.; Palioselitis, D.; Păvălaş, G. E.; Payet, K.; Payre, P.; Petrovic, J.; Piattelli, P.; Picot-Clemente, N.; Popa, V.; Pradier, T.; Presani, E.; Racca, C.; Reed, C.; Richardt, C.; Richter, R.; Rivière, C.; Robert, A.; Roensch, K.; Rostovtsev, A.; Ruiz-Rivas, J.; Rujoiu, M.; Russo, G. V.; Salesa, F.; Sapienza, P.; Schöck, F.; Schuller, J. P.; Schüssler, F.; Shanidze, R.; Simeone, F.; Spies, A.; Spurio, M.; Steijger, J. J. M.; Stolarczyk, T.; Sánchez-Losa, A.; Taiuti, M.; Tamburini, C.; Toscano, S.; Vallage, B.; Van Elewyck, V.; Vannoni, G.; Vecchi, M.; Vernin, P.; Wijnker, G.; Wilms, J.; de Wolf, E.; Yepes, H.; Zaborov, D.; Zornoza, J. D.; Zúñiga, J.

    2012-05-01

    The primary aim of ANTARES is neutrino astronomy with upward going muons created in charged current muon neutrino interactions in the detector and its surroundings. Downward going muons are background for neutrino searches. These muons are the decay products of cosmic-ray collisions in the Earth's atmosphere far above the detector. This paper presents a method to identify and count electromagnetic showers induced along atmospheric muon tracks with the ANTARES detector. The method is applied to both cosmic muon data and simulations and its applicability to the reconstruction of muon event energies is demonstrated.

  3. Theory of spin-fluctuation induced superconductivity in iron-based superconductors

    SciTech Connect

    Zhang, Junhua

    2011-01-01

    In this dissertation we focus on the investigation of the pairing mechanism in the recently discovered high-temperature superconductor, iron pnictides. Due to the proximity to magnetic instability of the system, we considered short-range spin fluctuations as the major mediating source to induce superconductivity. Our calculation supports the magnetic fluctuations as a strong candidate that drives Cooper-pair formation in this material. We find the corresponding order parameter to be of the so-called ss-wave type and show its evolution with temperature as well as the capability of supporting high transition temperature up to several tens of Kelvin. On the other hand, our itinerant model calculation shows pronounced spin correlation at the observed antiferromagnetic ordering wave vector, indicating the underlying electronic structure in favor of antiferromagnetic state. Therefore, the electronic degrees of freedom could participate both in the magnetic and in the superconducting properties. Our work shows that the interplay between magnetism and superconductivity plays an important role to the understanding of the rich physics in this material. The magnetic-excitation spectrum carries important information on the nature of magnetism and the characteristics of superconductivity. We analyze the spin excitation spectrum in the normal and superconducting states of iron pnictides in the magnetic scenario. As a consequence of the sign-reversed gap structure obtained in the above, a spin resonance mode appears below the superconducting transition temperature. The calculated resonance energy, scaled with the gap magnitude and the magnetic correlation length, agrees well with the inelastic neutron scattering (INS) measurements. More interestingly, we find a common feature of those short-range spin fluctuations that are capable of inducing a fully gapped ss state is the momentum anisotropy with elongated span along the direction transverse to the antiferromagnetic momentum

  4. Fluctuations in induced charge introduced by Te inclusions within CdZnTe radiation detectors

    SciTech Connect

    Bale, Derek S.

    2010-07-15

    Recently, homogenization theory based on a multiple-scale perturbation of the electron transport equation has been used to derive a mathematical framework for modeling the excess charge lost to Te inclusions within radiation detectors based on semi-insulating cadmium zinc telluride (CdZnTe). In that theory, the heterogeneous material is mathematically replaced by a homogenized CdZnTe crystal whose effective electron attenuation length incorporates the additional uniform electron trapping caused by the inclusions. In this paper, the homogenization theory is extended to incorporate fluctuations in the induced charge (i.e., charge collection nonuniformities) introduced by the random position and size distributions of a noncorrelated population of small (i.e, <20 {mu}m) Te inclusions. Analysis of the effective parameters derived within the homogenized framework is used to develop a probability distribution of effective electron attenuation lengths, and therefore effective mobility-lifetime products, as a function of both the position and size distribution of Te inclusions. Example distributions are detailed for the case of an exponential size distribution at various number densities. Further, it is demonstrated that the inclusion-induced material nonuniformities derived in this paper can be numerically sampled efficiently, making them applicable to Monte Carlo device simulation of realistic CdZnTe detectors. Simulated charge induction maps and pulse-height spectra are presented and compared to recently published measurements.

  5. Earthquake-induced water-level fluctuations at Yucca Mountain, Nevada, June 1992

    SciTech Connect

    O`Brien, G.M.

    1993-07-01

    This report presents earthquake-induced water-level and fluid-pressure data for wells in the Yucca Mountain area, Nevada, during June 1992. Three earthquakes occurred which caused significant water-level and fluid-pressure responses in wells. Wells USW H-5 and USW H-6 are continuously monitored to detect short-term responses caused by earthquakes. Two wells, monitored hourly, had significant, longer-term responses in water level following the earthquakes. On June 28, 1992, a 7.5-magnitude earthquake occurred near Landers, California causing an estimated maximum water-level change of 90 centimeters in well USW H-5. Three hours later a 6.6-magnitude earthquake occurred near Big Bear Lake, California; the maximum water-level fluctuation was 20 centimeters in well USW H-5. A 5.6-magnitude earthquake occurred at Little Skull Mountain, Nevada, on June 29, approximately 23 kilometers from Yucca Mountain. The maximum estimated short-term water-level fluctuation from the Little Skull Mountain earthquake was 40 centimeters in well USW H-5. The water level in well UE-25p {number_sign}1, monitored hourly, decreased approximately 50 centimeters over 3 days following the Little Skull Mountain earthquake. The water level in UE-25p {number_sign}1 returned to pre-earthquake levels in approximately 6 months. The water level in the lower interval of well USW H-3 increased 28 centimeters following the Little Skull Mountain earthquake. The Landers and Little Skull Mountain earthquakes caused responses in 17 intervals of 14 hourly monitored wells, however, most responses were small and of short duration. For several days following the major earthquakes, many smaller magnitude aftershocks occurred causing measurable responses in the continuously monitored wells.

  6. Electromagnetically induced transparency with large delay-bandwidth product induced by magnetic resonance near field coupling to electric resonance

    SciTech Connect

    Li, Hai-ming; Liu, Shao-bin Liu, Si-yuan; Zhang, Hai-feng; Bian, Bo-rui; Kong, Xiang-kun; Wang, Shen-yun

    2015-03-16

    In this paper, we numerically and experimentally demonstrate electromagnetically induced transparency (EIT)-like spectral response with magnetic resonance near field coupling to electric resonance. Six split-ring resonators and a cut wire are chosen as the bright and dark resonator, respectively. An EIT-like transmission peak located between two dips can be observed with incident magnetic field excitation. A large delay bandwidth product (0.39) is obtained, which has potential application in quantum optics and communications. The experimental results are in good agreement with simulated results.

  7. Depletion-induced forces and crowding in polymer-nanoparticle mixtures: Role of polymer shape fluctuations and penetrability.

    PubMed

    Lim, Wei Kang; Denton, Alan R

    2016-01-14

    Depletion forces and macromolecular crowding govern the structure and function of biopolymers in biological cells and the properties of polymer nanocomposite materials. To isolate and analyze the influence of polymer shape fluctuations and penetrability on depletion-induced interactions and crowding by nanoparticles, we model polymers as effective penetrable ellipsoids, whose shapes fluctuate according to the probability distributions of the eigenvalues of the gyration tensor of an ideal random walk. Within this model, we apply Monte Carlo simulation methods to compute the depletion-induced potential of mean force between hard nanospheres and crowding-induced shape distributions of polymers in the protein limit, in which polymer coils can be easily penetrated by smaller nanospheres. By comparing depletion potentials from simulations of ellipsoidal and spherical polymer models with predictions of polymer field theory and free-volume theory, we show that polymer depletion-induced interactions and crowding depend sensitively on polymer shapes and penetrability, with important implications for bulk thermodynamic phase behavior.

  8. Exposure to 50Hz-sinusoidal electromagnetic field induces DNA damage-independent autophagy.

    PubMed

    Shen, Yunyun; Xia, Ruohong; Jiang, Hengjun; Chen, Yanfeng; Hong, Ling; Yu, Yunxian; Xu, Zhengping; Zeng, Qunli

    2016-08-01

    As electromagnetic field (EMF) is commonly encountered within our daily lives, the biological effects of EMF are of great concern. Autophagy is a key process for maintaining cellular homeostasis, and it can also reveal cellular responses to environmental stimuli. In this study, we aim to investigate the biological effects of a 50Hz-sinusoidal electromagnetic field on autophagy and we identified its mechanism of action in Chinese Hamster Lung (CHL) cells. CHL cells were exposed to a 50Hz sinusoidal EMF at 0.4mT for 30min or 24h. In this study, we found that a 0.4mT EMF resulted in: (i) an increase in LC3-II expression and increased autophagosome formation; (ii) no significant difference in the incidence of γH2AX foci between the sham and exposure groups; (iii) reorganized actin filaments and increased pseudopodial extensions without promoting cell migration; and (iv) enhanced cell apoptosis when autophagy was blocked by Bafilomycin A1. These results implied that DNA damage was not directly involved in the autophagy induced by a 0.4mT 50Hz EMF. In addition, an EMF induced autophagy balanced the cellular homeostasis to protect the cells from severe adverse biological consequences.

  9. Coherent processes in electromagnetically induced absorption: a steady and transient study

    NASA Astrophysics Data System (ADS)

    Dimitrijević, J.; Arsenović, D.; Jelenković, B. M.

    2011-03-01

    A perturbation method was used to solve optical Bloch equations (OBEs) for the transition Fg=1→Fe=2, in order to describe the role of ground-level Zeeman coherences in the formation of electromagnetically induced absorption (EIA). A narrow Lorentzian peak, centered at zero value of the scanning magnetic field, appears in the analytical expression of the second-order correction of a density-matrix element for ground-level Zeeman coherences, (ρg-1, g+1)x2. Through analytical expressions for lower-order corrections of density-matrix elements, we were able to establish clear relations between the narrow Lorentzian in (ρg- 1, g+1)x2 and higher-order corrections of optical coherences, i.e. EIA. We see from analytical expressions that these two resonances have opposite signs and that EIA becomes electromagnetically induced transparency (EIT) in the limit of low efficiency of spontaneous transfer of coherences from excited-level to ground-level Zeeman sublevels. The transient behavior of EIA follows the time evolution of (ρg- 1, g+1)x2. After the coupling laser is turned on, both the Lorentzian peak in (ρg- 1, g+1)x2 and EIA reach steady state via over-damped oscillations.

  10. Electromagnetically-induced-absorption resonance with high contrast and narrow width in the Hanle configuration

    NASA Astrophysics Data System (ADS)

    Brazhnikov, D. V.; Taichenachev, A. V.; Tumaikin, A. M.; Yudin, V. I.

    2014-12-01

    The method for observing the high-contrast and narrow-width resonances of electromagnetically induced absorption (EIA) in the Hanle configuration under counter-propagating pump and probe light waves is proposed. Here, as an example, we study a ‘dark’ type of atomic dipole transition {{F}\\text{g}}={1}\\to {{F}\\text{e}}={1} in D1 line of 87Rb, where usually the electromagnetically induced transparency can be observed. To obtain the EIA signal one should properly choose the polarizations of light waves and intensities. In contrast to regular schemes for observing EIA signals (under a single traveling light wave in the Hanle configuration or under a bichromatic light field consisting of two traveling waves), the proposed scheme allows one to use buffer gas for significantly improving the properties of the resonance. Also the dramatic influence of atomic transition openness on the contrast of the resonance is revealed, which is advantageous in comparison with cyclic atomic transitions. The nonlinear resonances in a probe-wave transmitted signal with contrast close to 100% and sub-kHz widths can be obtained. The results are interesting in high-resolution spectroscopy, nonlinear and magneto-optics.

  11. Exposure to 50Hz-sinusoidal electromagnetic field induces DNA damage-independent autophagy.

    PubMed

    Shen, Yunyun; Xia, Ruohong; Jiang, Hengjun; Chen, Yanfeng; Hong, Ling; Yu, Yunxian; Xu, Zhengping; Zeng, Qunli

    2016-08-01

    As electromagnetic field (EMF) is commonly encountered within our daily lives, the biological effects of EMF are of great concern. Autophagy is a key process for maintaining cellular homeostasis, and it can also reveal cellular responses to environmental stimuli. In this study, we aim to investigate the biological effects of a 50Hz-sinusoidal electromagnetic field on autophagy and we identified its mechanism of action in Chinese Hamster Lung (CHL) cells. CHL cells were exposed to a 50Hz sinusoidal EMF at 0.4mT for 30min or 24h. In this study, we found that a 0.4mT EMF resulted in: (i) an increase in LC3-II expression and increased autophagosome formation; (ii) no significant difference in the incidence of γH2AX foci between the sham and exposure groups; (iii) reorganized actin filaments and increased pseudopodial extensions without promoting cell migration; and (iv) enhanced cell apoptosis when autophagy was blocked by Bafilomycin A1. These results implied that DNA damage was not directly involved in the autophagy induced by a 0.4mT 50Hz EMF. In addition, an EMF induced autophagy balanced the cellular homeostasis to protect the cells from severe adverse biological consequences. PMID:27177844

  12. Electromagnetically induced transparency in a spherical quantum dot with hydrogenic impurity in the external magnetic field

    NASA Astrophysics Data System (ADS)

    Pavlović, Vladan; Stevanović, Ljiljana

    2016-04-01

    In this paper we analyzed the realization of the electromagnetically induced transparency (EIT) effect in the spherical quantum dot with on-center hydrogenic impurity under the influence of the external magnetic field. Three energy levels of hydrogen impurity 1s0, 2p-1, and 3d-2, together with the probe and control laser fields, which induce σ- transitions between the given states, form a ladder configuration. Optical Bloch equations for such a system are solved in a stationary regime. Dependence of the susceptibility for such a system on the Rabi frequency of the control field, intensity of the external magnetic field, detuning of the control field, and decay rates coefficients are then discussed in detail. Finally, the explanation in dressed state picture is given.

  13. Optical Analog to Electromagnetically Induced Transparency in Cascaded Ring-Resonator Systems

    PubMed Central

    Wang, Yonghua; Zheng, Hua; Xue, Chenyang; Zhang, Wendong

    2016-01-01

    The analogue of electromagnetically induced transparency in optical methods has shown great potential in slow light and sensing applications. Here, we experimentally demonstrated a coupled resonator induced transparency system with three cascaded ring coupled resonators in a silicon chip. The structure was modeled by using the transfer matrix method. Influences of various parameters including coupling ratio of couplers, waveguide loss and additional loss of couplers on transmission characteristic and group index have been investigated theoretically and numerically in detail. The transmission character of the system was measured by the vertical grating coupling method. The enhanced quality factor reached 1.22 × 105. In addition, we further test the temperature performance of the device. The results provide a new method for the manipulation of light in highly integrated optical circuits and sensing applications. PMID:27463720

  14. Graphene-based electromagnetically induced transparency with coupling Fabry-Perot resonators.

    PubMed

    Zhuang, Huawei; Kong, Fanmin; Li, Kang; Sheng, Shiwei

    2015-08-20

    We investigate the plasmonic analog of electromagnetically induced transparency (EIT) using two adjacent graphene-based Fabry-Perot (F-P) resonators side coupling to a nanoribbon waveguide. By the coupling mode theory in time and F-P resonant model, the destructive interference from the coupling of the two F-P resonators results in the EIT-like optical response. The induced peak and width of the transparency window can be dynamically manipulated by varying the coupling distance of the two resonators, and the transparent window is easily shifted by tuning the resonator length or the chemical potential of the graphene nanoribbon. In order to verify the characteristics of slow light, the group index profile is analyzed at different coupling distances. The proposed graphene-based EIT-like system could open up new opportunities for potential applications in plasmonic slow light and optical information buffering devices.

  15. Plasmonic analog of electromagnetic-induced transparency of asymmetrical slots waveguide

    NASA Astrophysics Data System (ADS)

    Sun, Lin; Wang, Jicheng; Tang, Baojie; Wang, Xiaosai

    2015-08-01

    Electromagnetically induced transparency (EIT) has been proposed numerically in the plasmonic waveguides composed of unsymmetrical slots shaped metal-insulator-metal (MIM) structures. By the transmission line theory and Fabry-Perot model, the formation and evolution mechanisms of Plasmon induced transparency are exactly analyzed. The analysis shows that the peak of EIT-like transmission can be changed easily according to certain rules by adjusting the geometrical parameters of the slot structures, including the coupling distances and slot depths. We can find a new method to design nanoscale optical switch, devices in optical storage and optical computing. It is found that the slow light effects are emerged in the unsymmetrical slot structures. A small group velocity(c/80) can be achieved.

  16. Application of an induced field sensor for assessment of electromagnetic exposure from compact fluorescent lamps.

    PubMed

    Nadakuduti, Jagadish; Douglas, Mark; Capstick, Myles; Kühn, Sven; Kuster, Niels

    2012-02-01

    The development of scientifically sound instrumentation, methods, and procedures for the electromagnetic exposure assessment of compact fluorescent lamps (CFLs) is investigated. The incident and induced fields from 11 CFLs have been measured in the 10 kHz-1 MHz range, and they are compared with the levels for incandescent and light emitting diode (LED) bulbs. Commercially available equipment was used to measure the incident fields, while a novel sensor was built to assess the induced fields in humans. Incident electric field levels significantly exceed the International Commission on Non-Ionizing Radiation Protection (ICNIRP) reference levels at close distances for some sources, while the induced fields are within the ICNIRP basic restrictions. This demonstrates the importance of assessing the induced fields rather than the incident fields for these sources. Maximum current densities for CFLs are comparable to the limits (in the range of 9% to 56%), demonstrating the need for measurements to establish compliance. For the frequency range investigated, the induced fields were found to be considerably higher for CFLs than for incandescent light bulbs, while the exposure from the two LED bulbs was low. The proposed instrumentation and methods offer several advantages over an existing measurement standard, and the measurement uncertainty is significantly better than the assessment of electric and magnetic fields at close distances.

  17. Field models and numerical dosimetry inside an extremely-low-frequency electromagnetic bioreactor: the theoretical link between the electromagnetically induced mechanical forces and the biological mechanisms of the cell tensegrity.

    PubMed

    Mognaschi, Maria Evelina; Di Barba, Paolo; Magenes, Giovanni; Lenzi, Andrea; Naro, Fabio; Fassina, Lorenzo

    2014-01-01

    We have implemented field models and performed a detailed numerical dosimetry inside our extremely-low-frequency electromagnetic bioreactor which has been successfully used in in vitro Biotechnology and Tissue Engineering researches. The numerical dosimetry permitted to map the magnetic induction field (maximum module equal to about 3.3 mT) and to discuss its biological effects in terms of induced electric currents and induced mechanical forces (compression and traction). So, in the frame of the tensegrity-mechanotransduction theory of Ingber, the study of these electromagnetically induced mechanical forces could be, in our opinion, a powerful tool to understand some effects of the electromagnetic stimulation whose mechanisms remain still elusive.

  18. Suppression of nuclear spin bath fluctuations in self-assembled quantum dots induced by inhomogeneous strain.

    PubMed

    Chekhovich, E A; Hopkinson, M; Skolnick, M S; Tartakovskii, A I

    2015-02-23

    Interaction with nuclear spins leads to decoherence and information loss in solid-state electron-spin qubits. One particular, ineradicable source of electron decoherence arises from decoherence of the nuclear spin bath, driven by nuclear-nuclear dipolar interactions. Owing to its many-body nature nuclear decoherence is difficult to predict, especially for an important class of strained nanostructures where nuclear quadrupolar effects have a significant but largely unknown impact. Here, we report direct measurement of nuclear spin bath coherence in individual self-assembled InGaAs/GaAs quantum dots: spin-echo coherence times in the range 1.2-4.5 ms are found. Based on these values, we demonstrate that strain-induced quadrupolar interactions make nuclear spin fluctuations much slower compared with lattice-matched GaAs/AlGaAs structures. Our findings demonstrate that quadrupolar effects can potentially be used to engineer optically active III-V semiconductor spin-qubits with a nearly noise-free nuclear spin bath, previously achievable only in nuclear spin-0 semiconductors, where qubit network interconnection and scaling are challenging.

  19. Suppression of nuclear spin bath fluctuations in self-assembled quantum dots induced by inhomogeneous strain

    NASA Astrophysics Data System (ADS)

    Chekhovich, E. A.; Hopkinson, M.; Skolnick, M. S.; Tartakovskii, A. I.

    2015-02-01

    Interaction with nuclear spins leads to decoherence and information loss in solid-state electron-spin qubits. One particular, ineradicable source of electron decoherence arises from decoherence of the nuclear spin bath, driven by nuclear-nuclear dipolar interactions. Owing to its many-body nature nuclear decoherence is difficult to predict, especially for an important class of strained nanostructures where nuclear quadrupolar effects have a significant but largely unknown impact. Here, we report direct measurement of nuclear spin bath coherence in individual self-assembled InGaAs/GaAs quantum dots: spin-echo coherence times in the range 1.2-4.5 ms are found. Based on these values, we demonstrate that strain-induced quadrupolar interactions make nuclear spin fluctuations much slower compared with lattice-matched GaAs/AlGaAs structures. Our findings demonstrate that quadrupolar effects can potentially be used to engineer optically active III-V semiconductor spin-qubits with a nearly noise-free nuclear spin bath, previously achievable only in nuclear spin-0 semiconductors, where qubit network interconnection and scaling are challenging.

  20. Fluctuations of visual awareness: Combining motion-induced blindness with binocular rivalry

    PubMed Central

    Jaworska, Katarzyna; Lages, Martin

    2014-01-01

    Binocular rivalry (BR) and motion-induced blindness (MIB) are two phenomena of visual awareness where perception alternates between multiple states despite constant retinal input. Both phenomena have been extensively studied, but the underlying processing remains unclear. It has been suggested that BR and MIB involve the same neural mechanism, but how the two phenomena compete for visual awareness in the same stimulus has not been systematically investigated. Here we introduce BR in a dichoptic stimulus display that can also elicit MIB and examine fluctuations of visual awareness over the course of each trial. Exploiting this paradigm we manipulated stimulus characteristics that are known to influence MIB and BR. In two experiments we found that effects on multistable percepts were incompatible with the idea of a common oscillator. The results suggest instead that local and global stimulus attributes can affect the dynamics of each percept differently. We conclude that the two phenomena of visual awareness share basic temporal characteristics but are most likely influenced by processing at different stages within the visual system. PMID:25240063

  1. Fluctuations of visual awareness: combining motion-induced blindness with binocular rivalry.

    PubMed

    Jaworska, Katarzyna; Lages, Martin

    2014-09-19

    Binocular rivalry (BR) and motion-induced blindness (MIB) are two phenomena of visual awareness where perception alternates between multiple states despite constant retinal input. Both phenomena have been extensively studied, but the underlying processing remains unclear. It has been suggested that BR and MIB involve the same neural mechanism, but how the two phenomena compete for visual awareness in the same stimulus has not been systematically investigated. Here we introduce BR in a dichoptic stimulus display that can also elicit MIB and examine fluctuations of visual awareness over the course of each trial. Exploiting this paradigm we manipulated stimulus characteristics that are known to influence MIB and BR. In two experiments we found that effects on multistable percepts were incompatible with the idea of a common oscillator. The results suggest instead that local and global stimulus attributes can affect the dynamics of each percept differently. We conclude that the two phenomena of visual awareness share basic temporal characteristics but are most likely influenced by processing at different stages within the visual system.

  2. Suppression of nuclear spin bath fluctuations in self-assembled quantum dots induced by inhomogeneous strain.

    PubMed

    Chekhovich, E A; Hopkinson, M; Skolnick, M S; Tartakovskii, A I

    2015-01-01

    Interaction with nuclear spins leads to decoherence and information loss in solid-state electron-spin qubits. One particular, ineradicable source of electron decoherence arises from decoherence of the nuclear spin bath, driven by nuclear-nuclear dipolar interactions. Owing to its many-body nature nuclear decoherence is difficult to predict, especially for an important class of strained nanostructures where nuclear quadrupolar effects have a significant but largely unknown impact. Here, we report direct measurement of nuclear spin bath coherence in individual self-assembled InGaAs/GaAs quantum dots: spin-echo coherence times in the range 1.2-4.5 ms are found. Based on these values, we demonstrate that strain-induced quadrupolar interactions make nuclear spin fluctuations much slower compared with lattice-matched GaAs/AlGaAs structures. Our findings demonstrate that quadrupolar effects can potentially be used to engineer optically active III-V semiconductor spin-qubits with a nearly noise-free nuclear spin bath, previously achievable only in nuclear spin-0 semiconductors, where qubit network interconnection and scaling are challenging. PMID:25704639

  3. Spatiotemporal patterns of water table fluctuations and evapotranspiration induced by riparian vegetation in a semiarid area

    NASA Astrophysics Data System (ADS)

    Yue, Weifeng; Wang, Tiejun; Franz, Trenton E.; Chen, Xunhong

    2016-03-01

    Groundwater evapotranspiration (ETg) links various ecohydrological processes and is an important component in regional water budgets. In this study, an extensive monitoring network was established in a semiarid riparian area to investigate various controls on the spatiotemporal pattern of water table fluctuations (WTFs) and ETg induced by riparian vegetation. Along a vegetation gradient (˜1200 m), diurnal WTFs were observed during a growing season in areas covered by woody species (Populus sect. Aigeiros and Juniperus virginiana) and wet slough vegetation (Panicum virgatum and Bromus inermis) with deeper root systems; whereas, no diurnal WTFs were found in the middle section with shallower-rooted grasses (Poa pratensis and Carex sp.). The occurrence of diurnal WTFs was related to temperature-controlled plant phenology at seasonal scales and to radiation at subdaily scales. Daily ETg in the mid-growing season was calculated using the White method. The results revealed that depth to water table (DTWT) was the dominant control on ETg, followed by potential evapotranspiration (ETp). By combining the effects of DTWT and ETp, it was found that at shallower depths, ETg was more responsive to changes in ETp, due to the closer linkage of land surface processes with shallower groundwater. Finally, exponential relationships between ETg/ETp and DTWT were obtained at the study site, although those relationships varied considerably across the sites. This study demonstrates the complex interactions of WTFs and ETg with surrounding environmental variables and provides further insight into modeling ETg over different time scales and riparian vegetation.

  4. Electromagnetically Induced Transparency Experiments for the Advanced Undergraduate Laboratory: Suppression of Polarization Impurity and Stray Magnetic Fields

    NASA Astrophysics Data System (ADS)

    Campbell, Kaleb; Jackson, Richard; van Vleet, Matthew; Kuhnash, Kodi; Worth, Bradley; Day, Amanda; Bali, Samir

    2014-05-01

    We investigate electromagnetically induced transparency (EIT) and electromagnetically induced absorption (EIA) in rubidium vapor using a single laser beam and a scanning magnetic field co-aligned with the laser propagation direction. We show that polarization impurity, stray magnetic fields and imperfect optical alignments cause broadening of the EIT/EIA signal and other spurious effects. We describe a systematic approach to minimizing these undesired effects, which produces EIT/EIA signals nearly two orders of magnitude narrower than the natural linewidth. We gratefully acknowledge funding from the American Chemical Society Petroleum Research Fund and Miami University. We also acknowledge the Miami University Instrumentation Laboratory for their invaluable contributions.

  5. Underwater sediment analyses by laser induced breakdown spectroscopy and calibration procedure for fluctuating plasma parameters

    NASA Astrophysics Data System (ADS)

    Lazic, V.; Colao, F.; Fantoni, R.; Spizzichino, V.; Jovićević, S.

    2007-01-01

    Laser Induced Breakdown Spectroscopy (LIBS) was applied on sediments directly under water. The aim of the research was to develop a method for measuring the sediment elemental composition, including minor elements, which could be implemented in-situ. The plasma was generated by a double-pulse, Q-Switched Nd:YAG laser operated at 1064 nm. For signal detection, both ICCD and non-gated, compact detectors were used. The major difficulties in underwater sediment analyses are related to the natural and laser induced surface roughness, and to the sample softness. The latter is responsible for the formation of particle clouds above the surface, which scatter both the laser and plasma radiation, and often results in breakdown formation above the analyzed surface. In such cases, a broad sonoluminescence emission from water, formed during the gas bubble collapse was sometimes registered. Under optimized experimental conditions, even by using a non-gated detector and single shot acquisition, it was possible to detect several minor sediment constituents, such as titanium, barium, manganese and others. A crude estimation of the Limit of Detection (LODs) for these elements was performed by underwater measurements on certified soils/sediments. Due to strong shot-to-shot fluctuations in the plasma temperature, well correlated calibration curves, aimed for quantitative analyses, could only be obtained after applying an appropriate data processing procedure. The latter selects automatically only the spectra characterized by similar plasma parameters, which are related to their continuum spectral distribution. Application of such a procedure improves the measurement accuracy also in other surroundings and on samples different from the ones analyzed here.

  6. Disinfection of wastewater effluents with the Fenton-like process induced by electromagnetic fields.

    PubMed

    Rodríguez-Chueca, J; Mediano, A; Ormad, M P; Mosteo, R; Ovelleiro, J L

    2014-09-01

    This research work is focused on the application and assessment of effectiveness of the Fenton-like processes induced by radiofrequency for the inactivation of faecal bacteria (Escherichia coli and Enterococcus sp.) present in treated urban wastewater effluents. Fenton processes were carried out at near neutral pH (pH 5) with different iron sources, such as iron salts (ferric chloride, 5, 50 and 100 mg/L Fe(3+)), magnetite (1 g/L) and clay (80 g/L), hydrogen peroxide (25 mg/L) and in absence and presence of radiofrequency. Two different electromagnetic field intensities (1.57 and 3.68 kA/m) were used in Fenton processes induced by radiofrequency. Different agents used in the Fenton processes induced by electromagnetic fields (iron source, hydrogen peroxide and RF) were analyzed individually and in combination under the same experimental conditions. First assays of ferromagnetic material/H2O2/radiofrequency processes achieved promising results in terms of bacterial inactivation. For instance, Fe(3+)/H2O2/Radiofrequency achieved a maximum level of E. coli inactivation of 3.55 log after 10 min of treatment. These results are higher than those obtained in absence of radiofrequency. The thermal activation of iron atoms allows the Fenton reaction to intensify, increasing the final yield of the treatment. On the other hand, different behavior was observed in the inactivation of E. coli and Enterococcus sp. due to the structural differences between Gram-negative and Gram-positive bacteria.

  7. A field investigation of phreatophyte-induced fluctuations in the water table

    USGS Publications Warehouse

    Butler, J.J.; Kluitenberg, G.J.; Whittemore, D.O.; Loheide, S.P.; Jin, W.; Billinger, M.A.; Zhan, X.

    2007-01-01

    Hydrographs from shallow wells in vegetated riparian zones frequently display a distinctive pattern of diurnal water table fluctuations produced by variations in plant water use. A multisite investigation assessed the major controls on these fluctuations and the ecohydrologic insights that can be gleaned from them. Spatial and temporal variations in the amplitude of the fluctuations are primarily a function of variations in (1) the meteorological drivers of plant water use, (2) vegetation density, type, and vitality, and (3) the specific yield of sediments in the vicinity of the water table. Past hydrologic conditions experienced by the riparian zone vegetation, either in previous years or earlier within the same growing season, are also an important control. Diurnal water table fluctuations can be considered a diagnostic indicator of groundwater consumption by phreatophytes at most sites, so the information embedded within these fluctuations should be more widely exploited in ecohydrologic studies. Copyright 2007 by the American Geophysical Union.

  8. Underground Measurements of Electromagnetic Radiation Related to Stress-induced Fractures in the Odenwald Mountains (Germany)

    NASA Astrophysics Data System (ADS)

    Lichtenberger, Marco

    2006-08-01

    The regional stress field at Wald-Michelbach (Odenwald Mountains, Germany) induces a secondary stress field around the space of the local railway tunnel. Resulting maximum shear stresses produce microfractures, which emit electromagnetic radiation (EMR). From EMR measured along the cross section and the long axis of the tunnel, the regional stress field is determined by a correlation of detected impulses per time with stresses calculated from the orientation of the tunnel, its diameter, and topographic load. The major horizontal principal stress has an azimuth of 103°. At times, strongly alternating EMR values are observed, which indicate electromagnetic disturbances of unknown origin. Such disturbances are identified by repeated measurements and are not evaluated. The repeated measurements, which are not disturbed, differ with median 112 impulses per 100 ms. This difference corresponds to 0.037 MPa and indicates a good reproducibility of the results. Regional stress magnitudes and the WNW-ESE orientation of the major horizontal principal stress indicate a minor N S directed tensional force at the western shoulder of the Upper Rhine Graben.

  9. Attosecond Electro-Magnetic Forces Acting on Metal Nanospheres Induced By Relativistic Electrons

    NASA Astrophysics Data System (ADS)

    Lagos, M. J.; Batson, P. E.; Reyes-Coronado, A.; Echenique, P. M.; Aizpurua, J.

    2014-03-01

    Swift electron scattering near nanoscale materials provides information about light-matter behavior, including induced forces. We calculate time-dependent electromagnetic forces acting on 1-1.5 nm metal nanospheres induced by passing swift electrons, finding both impulse-like and oscillatory response forces. Initially, impulse-like forces are generated by a competition between attractive electric forces and repulsive magnetic forces, lasting a few attoseconds (5-10 as). Oscillatory, plasmonic response forces take place later in time, last a few femtoseconds (1- 5 fs), and apparently rely on photon emission by decay of the electron-induced surface plasmons. A comparison of the strength of these two forces suggests that the impulse-like behavior dominates the process, and can transfer significant linear momentum to the sphere. Our results advance understanding of the physics behind the observation of both attractive and repulsive behavior of gold nano-particles induced by electron beams in aberration-corrected electron microscopy. Work supported under DOE, Award # DE-SC0005132, Basque Gov. project ETORTEK inano, Spanish Ministerio de Ciencia e Innovacion, No. FIS2010-19609-C02-01.

  10. Resolution of hyperfine transitions in metastable 83Kr using electromagnetically induced transparency

    NASA Astrophysics Data System (ADS)

    Kale, Y. B.; Mishra, S. R.; Tiwari, V. B.; Singh, S.; Rawat, H. S.

    2015-05-01

    Narrow linewidth signals of electromagnetically induced transparency (EIT) in the metastable 83Kr have been observed. Various hyperfine transitions in the 4 p55 s [3/2 ] 2 to 4 p55 p [5/2 ] 3 manifolds of 83Kr have been identified through the experimentally observed EIT signals. Some unresolved or poorly resolved hyperfine transitions in saturated absorption spectroscopy (SAS) are clearly resolved in the present work. Using the spectral separation of these EIT identified hyperfine transitions, the magnetic hyperfine constant (A ) and the electric quadrupole hyperfine constant (B ) are determined with improved accuracy for 4 p55 s [3/2 ] 2 and 4 p55 p [5/2 ] 3 manifolds.

  11. Method for identifying electromagnetically induced transparency in a tunable circuit quantum electrodynamics system

    NASA Astrophysics Data System (ADS)

    Liu, Qi-Chun; Li, Tie-Fu; Luo, Xiao-Qing; Zhao, Hu; Xiong, Wei; Zhang, Ying-Shan; Chen, Zhen; Liu, J. S.; Chen, Wei; Nori, Franco; Tsai, J. S.; You, J. Q.

    2016-05-01

    Electromagnetically induced transparency (EIT) has been realized in atomic systems, but fulfilling the EIT conditions for artificial atoms made from superconducting circuits is a more difficult task. Here we report an experimental observation of the EIT in a tunable three-dimensional transmon by probing the cavity transmission. To fulfill the EIT conditions, we tune the transmon to adjust its damping rates by utilizing the effect of the cavity on the transmon states. From the experimental observations, we clearly identify the EIT and Autler-Townes splitting (ATS) regimes as well as the transition regime in between. Also, the experimental data demonstrate that the threshold ΩAIC determined by the Akaike information criterion can describe the EIT-ATS transition better than the threshold ΩEIT given by the EIT theory.

  12. Electromagnetically induced transparency and steady-state propagation characteristics in Doppler broadened diamond systems

    NASA Astrophysics Data System (ADS)

    Baig Mirza, Azeem; Singh, Suneel

    2015-01-01

    We explore the feasibility of attaining simultaneous electromagnetically induced transparency (EIT) and efficient nonlinear generation in different configurations of Doppler broadened diamond (double-cascade) systems such as, the frequency up-conversion, nearly degenerate and degenerate scheme. We show that EIT and nonlinear generation efficiency depend critically on the type of residual Doppler broadening present in each of the two cascade subsystems constituting the diamond system. Furthermore, it is observed that nonlinear generation with perfect EIT simultaneously in both subsystems is not possible as the process of nonlinear generation actually tends to oppose EIT. Yet in an extended medium, on resonance field propagation under matched conditions for probe and generated signal can occur when a balance (equilibrium) is established between these two competing processes.

  13. Electromagnetically induced transparency in an inhomogeneously broadened {Lambda} transition with multiple excited levels

    SciTech Connect

    Mishina, O. S.; Scherman, M.; Lombardi, P.; Ortalo, J.; Bramati, A.; Laurat, J.; Giacobino, E.; Felinto, D.; Sheremet, A. S.; Kupriyanov, D. V.

    2011-05-15

    Electromagnetically induced transparency (EIT) has mainly been modeled for three-level systems. In particular, considerable interest has been dedicated to the {Lambda} configuration, with two ground states and one excited state. However, in the alkali-metal atoms, which are commonly used, the hyperfine interaction in the excited state introduces several levels which simultaneously participate in the scattering process. When the Doppler broadening is comparable with the hyperfine splitting in the upper state, the three-level {Lambda} model does not reproduce the experimental results. Here we theoretically investigate the EIT in a hot vapor of alkali-metal atoms and demonstrate that it can be strongly reduced by the presence of multiple excited levels. Given this model, we also show that well-designed optical pumping enables us to significantly recover the transparency.

  14. Electromagnetically induced transparency metamaterial based on spoof localized surface plasmons at terahertz frequencies

    PubMed Central

    Liao, Zhen; Liu, Shuo; Ma, Hui Feng; Li, Chun; Jin, Biaobing; Cui, Tie Jun

    2016-01-01

    We numerically and experimentally demonstrate a plasmonic metamaterial whose unit cell is composed of an ultrathin metallic disk and four ultrathin metallic spiral arms at terahertz frequencies, which supports both spoof electric and magnetic localized surface plasmon (LSP) resonances. We show that the resonant wavelength is much larger than the size of the unit particle, and further find that the resonant wavelength is very sensitive to the particle’s geometrical dimensions and arrangements. It is clearly illustrated that the magnetic LSP resonance exhibits strong dependence to the incidence angle of terahertz wave, which enables the design of metamaterials to achieve an electromagnetically induced transparency effect in the terahertz frequencies. This work opens up the possibility to apply for the surface plasmons in functional devices in the terahertz band. PMID:27277417

  15. Localization of atomic excitation beyond the diffraction limit using electromagnetically induced transparency

    NASA Astrophysics Data System (ADS)

    Miles, J. A.; Das, Diptaranjan; Simmons, Z. J.; Yavuz, D. D.

    2015-09-01

    We experimentally demonstrate the localization of excitation between hyperfine ground states of 87Rb atoms to as small as λ /13 -wide spatial regions. We use ultracold atoms trapped in a dipole trap and utilize electromagnetically induced transparency (EIT) for the atomic excitation. The localization is achieved by combining a spatially varying coupling laser (standing wave) with the intensity dependence of EIT. The excitation is fast (150 ns laser pulses) and the dark-state fidelity can be made higher than 94% throughout the standing wave. Because the width of the localized regions is much smaller than the wavelength of the driving light, traditional optical imaging techniques cannot resolve the localized features. Therefore, to measure the excitation profile, we use an autocorrelation-like method where we perform two EIT sequences separated by a time delay, during which we move the standing wave.

  16. Temporal buildup of electromagnetically induced transparency and absorption resonances in degenerate two-level transitions

    NASA Astrophysics Data System (ADS)

    Valente, P.; Failache, H.; Lezama, A.

    2003-01-01

    The temporal evolution of electromagnetically induced transparency (EIT) and absorption (EIA) coherence resonances in pump-probe spectroscopy of degenerate two-level atomic transition is studied for light intensities below saturation. Analytical expressions for the transient absorption spectra are given for simple model systems and a model for the calculation of the time-dependent response of realistic atomic transitions, where the Zeeman degeneracy is fully accounted for, is presented. EIT and EIA resonances have a similar (opposite sign) time-dependent line shape, however, the EIA evolution is slower and thus narrower lines are observed for long interaction time. Qualitative agreement with the theoretical predictions is obtained for the transient probe absorption on the 85Rb D2 line in an atomic beam experiment.

  17. Surface oscillations — A possible source of fracture induced electromagnetic radiation

    NASA Astrophysics Data System (ADS)

    Rabinovitch, A.; Frid, V.; Bahat, D.

    2007-02-01

    Radio frequency electromagnetic radiation (EMR) registered hundreds of kilometres away from an earthquake epicentre is detected hours before earthquakes. Yet, accurate earthquakes prediction by their self-induced EMR still remains in its infancy due in part to the lack of understanding of EMR's origin. Here we present a viable model of this origin, according to which EMR is emitted by an oscillating dipole created by ions moving collectively as a surface wave on both sides of the crack; when the crack halts, the EMR pulse amplitude decays by interaction with bulk phonons. The model is shown to be able to provide crack dimensions and velocities, to explain some general similarities of different fracturing processes and indicate the existence of a general failure mechanism. Results raise the hope of developing an EMR based genuine earthquake prediction system.

  18. Tuning all-Optical Analog to Electromagnetically Induced Transparency in nanobeam cavities using nanoelectromechanical system

    PubMed Central

    Shi, Peng; Zhou, Guangya; deng, Jie; Tian, Feng; Chau, Fook Siong

    2015-01-01

    We report the observations of all-optical electromagnetically induced transparency in nanostructures using waveguide side-coupled with photonic crystal nanobeam cavities, which has measured linewidths much narrower than individual resonances. The quality factor of transparency resonance can be 30 times larger than those of measured individual resonances. When the gap between cavity and waveguide is reduced to 10 nm, the bandwidth of destructive interference region can reach 10 nm while the width of transparency resonance is 0.3 nm. Subsequently, a comb-drive actuator is introduced to tune the line shape of the transparency resonance. The width of the peak is reduced to 15 pm and the resulting quality factor exceeds 105. PMID:26415907

  19. Electromagnetically induced transparency metamaterial based on spoof localized surface plasmons at terahertz frequencies.

    PubMed

    Liao, Zhen; Liu, Shuo; Ma, Hui Feng; Li, Chun; Jin, Biaobing; Cui, Tie Jun

    2016-01-01

    We numerically and experimentally demonstrate a plasmonic metamaterial whose unit cell is composed of an ultrathin metallic disk and four ultrathin metallic spiral arms at terahertz frequencies, which supports both spoof electric and magnetic localized surface plasmon (LSP) resonances. We show that the resonant wavelength is much larger than the size of the unit particle, and further find that the resonant wavelength is very sensitive to the particle's geometrical dimensions and arrangements. It is clearly illustrated that the magnetic LSP resonance exhibits strong dependence to the incidence angle of terahertz wave, which enables the design of metamaterials to achieve an electromagnetically induced transparency effect in the terahertz frequencies. This work opens up the possibility to apply for the surface plasmons in functional devices in the terahertz band. PMID:27277417

  20. Coherent pump-probe spectroscopy in sodium vapor: From electromagnetically induced transparency to parametric amplification

    SciTech Connect

    Takahashi, Ken-ichi; Hayashi, Nobuhito; Kido, Hiroaki; Sugimura, Shota; Hombo, Naoya; Mitsunaga, Masaharu

    2011-06-15

    We have theoretically and experimentally investigated coherent pump-probe spectra for the 3S{sub 1/2}-3P{sub 1/2} D1 transition of sodium atomic vapor. Probe transmission spectra in the presence of a coupling beam exhibit dramatic changes depending on experimental conditions. In the weak-excitation, low-atomic-density limit, the spectra are mainly characterized by electromagnetically induced transparency (EIT) and saturated absorption, but for the strong-excitation, high-density case, parametric amplification (PA) is dominant, featuring high probe gain and Stokes-wave generation. We have developed a theory that can explain these two seemingly totally different phenomena (EIT and PA) within the same theoretical framework by manipulating a few experimentally controllable parameters, and have successfully reproduced the observed spectra. Other than the main spectral features, many other interesting physical processes have been predicted and observed.

  1. Two-photon dichroic atomic vapor laser lock using electromagnetically induced transparency and absorption

    SciTech Connect

    Becerra, F. E.; Willis, R. T.; Rolston, S. L.; Orozco, L. A.

    2009-07-15

    We demonstrate a technique to lock the frequency of a laser to a transition between two excited states in Rb vapor using a two-photon process in the presence of a weak magnetic field. We use a ladder configuration from specific hyperfine sublevels of the 5S{sub 1/2}, 5P{sub 3/2}, and 5D{sub 5/2} levels. This atomic configuration can show electromagnetically induced transparency and absorption processes. The error signal comes from the difference in the transparency or absorption felt by the two orthogonal polarizations of the probe beam. A simplified model is in good quantitative agreement with the observed signals for the experimental parameters. We have used this technique to lock the frequency of the laser up to 1.5 GHz off atomic resonance.

  2. Nonlinear Generation of Electromagnetic Waves through Induced Scattering by Thermal Plasma.

    PubMed

    Tejero, E M; Crabtree, C; Blackwell, D D; Amatucci, W E; Mithaiwala, M; Ganguli, G; Rudakov, L

    2015-01-01

    We demonstrate the conversion of electrostatic pump waves into electromagnetic waves through nonlinear induced scattering by thermal particles in a laboratory plasma. Electrostatic waves in the whistler branch are launched that propagate near the resonance cone. When the amplitude exceeds a threshold ~5 × 10(-6) times the background magnetic field, wave power is scattered below the pump frequency with wave normal angles (~59°), where the scattered wavelength reaches the limits of the plasma column. The scattered wave has a perpendicular wavelength that is an order of magnitude larger than the pump wave and longer than the electron skin depth. The amplitude threshold, scattered frequency spectrum, and scattered wave normal angles are in good agreement with theory. The results may affect the analysis and interpretation of space observations and lead to a comprehensive understanding of the nature of the Earth's plasma environment. PMID:26647962

  3. Spectral shift and dephasing of electromagnetically induced transparency in an interacting Rydberg gas

    NASA Astrophysics Data System (ADS)

    Han, Jingshan; Vogt, Thibault; Li, Wenhui

    2016-10-01

    We perform spectroscopic measurements of electromagnetically induced transparency (EIT) in a strongly interacting Rydberg gas. We observe a significant spectral shift and attenuation of the transparency resonance due to the presence of interactions between Rydberg atoms. We characterize the attenuation as the result of an effective dephasing and show that the shift and the dephasing rate increase versus atomic density, probe Rabi frequency, and principal quantum number of Rydberg states. Moreover, we find that the spectral shift is reduced if the size of a Gaussian atomic cloud is increased and that the dephasing rate increases with the EIT pulse duration at large-parameter regimes. We simulate our experiment with a semianalytical model, which yields results in good agreement with our experimental data.

  4. Large Fizeau's light-dragging effect in a moving electromagnetically induced transparent medium

    NASA Astrophysics Data System (ADS)

    Kuan, Pei-Chen; Huang, Chang; Chan, Wei Sheng; Kosen, Sandoko; Lan, Shau-Yu

    2016-10-01

    As one of the most influential experiments on the development of modern macroscopic theory from Newtonian mechanics to Einstein's special theory of relativity, the phenomenon of light dragging in a moving medium has been discussed and observed extensively in different types of systems. To have a significant dragging effect, the long duration of light travelling in the medium is preferred. Here we demonstrate a light-dragging experiment in an electromagnetically induced transparent cold atomic ensemble and enhance the dragging effect by at least three orders of magnitude compared with the previous experiments. With a large enhancement of the dragging effect, we realize an atom-based velocimeter that has a sensitivity two orders of magnitude higher than the velocity width of the atomic medium used. Such a demonstration could pave the way for motional sensing using the collective state of atoms in a room temperature vapour cell or solid state material.

  5. Subluminal and superluminal terahertz radiation in metamaterials with electromagnetically induced transparency.

    PubMed

    Bai, Zhengyang; Hang, Chao; Huang, Guoxiang

    2013-07-29

    We propose a scheme to design a new type of optical metamaterial that can mimic the functionality of four-state atomic systems of N-type energy-level configuration with electromagnetically induced transparency (EIT). We show that in such metamaterial a transition from a single EIT to a double EIT of terahertz radiation may be easily achieved by actively tuning the intensity of the infrared pump field or passively tuning the geometrical parameters of resonator structures. In addition, the group velocity of the terahertz radiation can be varied from subluminal to superluminal by changing the pump field intensity. The scheme suggested here may be used to construct chip-scale slow and fast light devices and to realize rapidly responded switching of terahertz radiation at room temperature.

  6. Nonlinear Generation of Electromagnetic Waves through Induced Scattering by Thermal Plasma.

    PubMed

    Tejero, E M; Crabtree, C; Blackwell, D D; Amatucci, W E; Mithaiwala, M; Ganguli, G; Rudakov, L

    2015-01-01

    We demonstrate the conversion of electrostatic pump waves into electromagnetic waves through nonlinear induced scattering by thermal particles in a laboratory plasma. Electrostatic waves in the whistler branch are launched that propagate near the resonance cone. When the amplitude exceeds a threshold ~5 × 10(-6) times the background magnetic field, wave power is scattered below the pump frequency with wave normal angles (~59°), where the scattered wavelength reaches the limits of the plasma column. The scattered wave has a perpendicular wavelength that is an order of magnitude larger than the pump wave and longer than the electron skin depth. The amplitude threshold, scattered frequency spectrum, and scattered wave normal angles are in good agreement with theory. The results may affect the analysis and interpretation of space observations and lead to a comprehensive understanding of the nature of the Earth's plasma environment.

  7. Optical control of light propagation in photonic crystal based on electromagnetically induced transparency

    NASA Astrophysics Data System (ADS)

    Dan, Wang; Jin-Ze, Wu; Jun-Xiang, Zhang

    2016-06-01

    A kind of photonic crystal structure with modulation of the refractive index is investigated both experimentally and theoretically for exploiting electromagnetically induced transparency (EIT). The combination of EIT with periodically modulated refractive index medium gives rise to high efficiency reflection as well as forbidden transmission in a three-level atomic system coupled by standing wave. We show an accurate theoretical simulation via transfer-matrix theory, automatically accounting for multilayer reflections, thus fully demonstrate the existence of photonic crystal structure in atomic vapor. Project supported by the National Natural Science Foundation of China (Grant No. 11574188) and the Project for Excellent Research Team of the National Natural Science Foundation of China (Grant No. 61121064).

  8. Perturbative approach in the frequency domain for the intensity correlation spectrum in electromagnetically induced transparency

    NASA Astrophysics Data System (ADS)

    Florez, H. M.; González, C.; Martinelli, M.

    2016-07-01

    Correlation spectroscopy has been proposed as a spectroscopic technique for measuring the coherence between the ground states in electromagnetically induced transparency (EIT). While in the time domain the steep dispersion in the EIT condition accounts for the robustness of the correlation linewidth against power broadening, such physical insight was not directly established in the frequency domain. We propose a perturbative approach to describe the correlation spectroscopy of two noisy lasers coupled to a Λ transition in cold atoms, leading to EIT. Such approach leads to an analytical expression that maps the intensity correlation directly in terms of the absorption and dispersion of the light fields. Low and high perturbative regimes are investigated and demonstrate that, for coherent light sources, the first-order term in perturbation expansion represents a sufficient description for the correlation. Sideband resonances are also observed, showing the richness of the frequency domain approach.

  9. Electromagnetically induced transparency using a superconducting artificial atom with optimized level anharmonicity

    NASA Astrophysics Data System (ADS)

    Shao, Zhu-Lei; Feng, Zhi-Bo

    2016-04-01

    We propose a theoretical scheme to implement electromagnetically induced transparency (EIT) using an artificial atom of superconducting circuit. Allowed by the selection rule, two kinds of interactions between the atom and driving fields can be obtained, in which we focus on the leakage effect. In terms of dark-state mechanism in generating EIT, the leakage could destroy the EIT considerably. By removing the leakage effect in an optimized three-level atom, we consider a realization of EIT through the technique of density matrix. Furthermore, another effective way to optimize the level anharmonicity is analyzed in a dressing-state method. The scheme could provide a promising approach for experimentally improving EIT with the artificial atoms.

  10. Nonlinear Generation of Electromagnetic Waves through Induced Scattering by Thermal Plasma

    PubMed Central

    Tejero, E. M.; Crabtree, C.; Blackwell, D. D.; Amatucci, W. E.; Mithaiwala, M.; Ganguli, G.; Rudakov, L.

    2015-01-01

    We demonstrate the conversion of electrostatic pump waves into electromagnetic waves through nonlinear induced scattering by thermal particles in a laboratory plasma. Electrostatic waves in the whistler branch are launched that propagate near the resonance cone. When the amplitude exceeds a threshold ~5 × 10−6 times the background magnetic field, wave power is scattered below the pump frequency with wave normal angles (~59°), where the scattered wavelength reaches the limits of the plasma column. The scattered wave has a perpendicular wavelength that is an order of magnitude larger than the pump wave and longer than the electron skin depth. The amplitude threshold, scattered frequency spectrum, and scattered wave normal angles are in good agreement with theory. The results may affect the analysis and interpretation of space observations and lead to a comprehensive understanding of the nature of the Earth’s plasma environment. PMID:26647962

  11. Large Fizeau's light-dragging effect in a moving electromagnetically induced transparent medium

    PubMed Central

    Kuan, Pei-Chen; Huang, Chang; Chan, Wei Sheng; Kosen, Sandoko; Lan, Shau-Yu

    2016-01-01

    As one of the most influential experiments on the development of modern macroscopic theory from Newtonian mechanics to Einstein's special theory of relativity, the phenomenon of light dragging in a moving medium has been discussed and observed extensively in different types of systems. To have a significant dragging effect, the long duration of light travelling in the medium is preferred. Here we demonstrate a light-dragging experiment in an electromagnetically induced transparent cold atomic ensemble and enhance the dragging effect by at least three orders of magnitude compared with the previous experiments. With a large enhancement of the dragging effect, we realize an atom-based velocimeter that has a sensitivity two orders of magnitude higher than the velocity width of the atomic medium used. Such a demonstration could pave the way for motional sensing using the collective state of atoms in a room temperature vapour cell or solid state material. PMID:27694938

  12. Ag induced electromagnetic interference shielding of Ag-graphite/PVDF flexible nanocomposites thinfilms

    NASA Astrophysics Data System (ADS)

    Kumaran, R.; Alagar, M.; Dinesh Kumar, S.; Subramanian, V.; Dinakaran, K.

    2015-09-01

    We report Ag nanoparticle induced Electromagnetic Interference (EMI) shielding in a flexible composite films of Ag nanoparticles incorporated graphite/poly-vinylidene difluoride (PVDF). PVDF nanocomposite thin-films were synthesized by intercalating Ag in Graphite (GIC) followed by dispersing GIC in PVDF. The X-ray diffraction analysis and the high-resolution transmission electron microscope clearly dictate the microstructure of silver nanoparticles in graphite intercalated composite of PVDF matrix. The conductivity values of nanocomposites are increased upto 2.5 times when compared to neat PVDF having a value of 2.70 S/cm at 1 MHz. The presence of Ag broadly enhanced the dielectric constant and lowers the dielectric loss of PVDF matrix proportional to Ag content. The EMI shielding effectiveness of the composites is 29.1 dB at 12.4 GHz for the sample having 5 wt. % Ag and 10 wt. % graphite in PVDF.

  13. Line-shape comparison of electromagnetically induced transparency and Raman Ramsey fringes in sodium vapor

    NASA Astrophysics Data System (ADS)

    Yoshida, Ichiro; Hayashi, Nobuhito; Fujita, Kazuki; Taniguchi, Shuya; Hoshina, Yoshitaka; Mitsunaga, Masaharu

    2013-02-01

    We have simultaneously studied electromagnetically induced transparency (EIT) and Raman Ramsey fringes (RRF) in sodium vapor, in the same theoretical framework and the same experimental scheme. RRF spectra and EIT spectra can be simply distinguished by whether the gate timing of the detection is set at the beginning (RRF) or at the end (EIT) of the excitation pulses. The EIT spectral peaks exhibited pronounced ac Stark shifts linearly depending upon the pumping power (8.8 kHz/mW), while in the RRF spectra such shifts were almost negligible (0.19 kHz/mW), provided that the pulse separation is sufficiently large. This fact promotes RRF as a strong candidate for next-generation compact atomic clocks. Transient spectra in between RRF and EIT have also been investigated by changing the gate timing within the excitation pulse, and the transition time from RRF to EIT was found to be of the order of a few microseconds.

  14. Goos-Hänchen shift in a standing-wave-coupled electromagnetically-induced-transparency medium

    NASA Astrophysics Data System (ADS)

    Zhang, Xiao-Jun; Wang, Hai-Hua; Liang, Zhi-Peng; Xu, Yan; Fan, Cun-Bo; Liu, Cheng-Zhi; Gao, Jin-Yue

    2015-03-01

    The Goos-Hänchen shift of the system composed by two cavity walls and an intracavity atomic sample is presented. The atomic sample is treated as a four-level double-Λ system, driven by the two counterpropagating coupling fields. The probe field experiences the discontinuous refractive index variation and is reflected. Moreover, under the phase-matching condition, the four-wave mixing effect based on electromagnetically induced transparency can cause effective reflection. The Goos-Hänchen shifts appear in both situations and are carefully investigated in this article. We refer to the first one with the incident and reflected light having identical wavelength as the linear Goos-Hänchen shift, and the second one with the reflection wavelength determined by the phase-matching condition as the nonlinear Goos-Hänchen shift. The differences between the two kinds of shifts, such as the incident angle range, conditions for the shift peaks, and controllability, are discussed.

  15. Electromagnetically induced transparency without a Doppler background in a multilevel ladder-type cesium atomic system

    SciTech Connect

    Yang Baodong; Gao Jing; Zhang Tiancai; Wang Junmin

    2011-01-15

    We present an investigation of electromagnetically induced transparency (EIT) without Doppler background due to a locked probe laser. The EIT is theoretically studied based on a multilevel ladder-type cesium atomic system 6S{sub 1/2}-6P{sub 3/2}-8S{sub 1/2} in a room-temperature vapor cell. The experimental results agree with the theoretical calculations. Compared with the traditional EIT spectra with a Doppler profile limiting the spectral resolution for keeping the coupling laser locked and scanning the probe laser, these EIT spectra with the probe laser locked and the coupling laser scanned have a flat background, which seem be of great benefit for applications such as the measurement of hyperfine intervals between excited states, the study of highly excited Rydberg states, laser-frequency stabilization, etc.

  16. Electromagnetically induced transparency metamaterial based on spoof localized surface plasmons at terahertz frequencies

    NASA Astrophysics Data System (ADS)

    Liao, Zhen; Liu, Shuo; Ma, Hui Feng; Li, Chun; Jin, Biaobing; Cui, Tie Jun

    2016-06-01

    We numerically and experimentally demonstrate a plasmonic metamaterial whose unit cell is composed of an ultrathin metallic disk and four ultrathin metallic spiral arms at terahertz frequencies, which supports both spoof electric and magnetic localized surface plasmon (LSP) resonances. We show that the resonant wavelength is much larger than the size of the unit particle, and further find that the resonant wavelength is very sensitive to the particle’s geometrical dimensions and arrangements. It is clearly illustrated that the magnetic LSP resonance exhibits strong dependence to the incidence angle of terahertz wave, which enables the design of metamaterials to achieve an electromagnetically induced transparency effect in the terahertz frequencies. This work opens up the possibility to apply for the surface plasmons in functional devices in the terahertz band.

  17. Resonant Rydberg Dressing of Alkaline-Earth Atoms via Electromagnetically Induced Transparency.

    PubMed

    Gaul, C; DeSalvo, B J; Aman, J A; Dunning, F B; Killian, T C; Pohl, T

    2016-06-17

    We develop an approach to generate finite-range atomic interactions via optical Rydberg-state excitation and study the underlying excitation dynamics in theory and experiment. In contrast to previous work, the proposed scheme is based on resonant optical driving and the establishment of a dark state under conditions of electromagnetically induced transparency (EIT). Analyzing the driven dissipative dynamics of the atomic gas, we show that the interplay between coherent light coupling, radiative decay, and strong Rydberg-Rydberg atom interactions leads to the emergence of sizable effective interactions while providing remarkably long coherence times. The latter are studied experimentally in a cold gas of strontium atoms for which the proposed scheme is most efficient. Our measured atom loss is in agreement with the theoretical prediction based on binary effective interactions between the driven atoms. PMID:27367387

  18. Heterogeneity in (2-butoxyethanol + water) mixtures: Hydrophobicity-induced aggregation or criticality-driven concentration fluctuations?

    NASA Astrophysics Data System (ADS)

    Indra, Sandipa; Biswas, Ranjit

    2015-05-01

    Micro-heterogeneity in aqueous solutions of 2-butoxyethanol (BE), a system with closed loop miscibility gap, has been explored via absorption and time-resolved fluorescence measurements of a dissolved dipolar solute, coumarin 153 (C153), in the water-rich region at various BE mole fractions (0 ≤ XBE ≤ 0.25) in the temperature range, 278 ≤ T/K ≤ 320. Evidences for both alcohol-induced H-bond strengthening and subsequent structural transition of H-bond network have been observed. Analyses of steady state and time-resolved spectroscopic data for these aqueous mixtures and comparisons with the results for aqueous solutions of ethanol and tertiary butanol indicate that alcohol aggregation in BE/water mixtures is driven by hydrophobic interaction with no or insignificant role for criticality-driven concentration fluctuations preceding phase separation. Excitation energy dependence of fluorescence emission of C153 confirms formation of aggregated structures at very low BE mole fractions. No asymptotic critical power law dependence for relaxation rates of the type, k ∝ (|T - Tc|/Tc)γ, with γ denoting universal critical constant, has been observed for both solute's rotational relaxation and population relaxation rates in these mixtures upon either approaching to critical concentration or critical temperature. Estimated activation energies for rotational relaxation rate of C153 and solution viscosity have been found to follow each other with no abrupt changes in either of them at any mixture composition. In addition, measured C153 rotation times at various compositions and temperatures reflect near-hydrodynamic viscosity coupling through the dependence, <τr> ∝ (η/T)p, with p = 0.8-1.0, suggesting solute's orientational relaxation dynamics being, on an average, temporally homogeneous.

  19. Comparison of theories for gravity wave induced fluctuations in airglow emissions

    NASA Technical Reports Server (NTRS)

    Walterscheid, R. L.; Schubert, G.; Hickey, M. P.

    1994-01-01

    A comparison is undertaken of theories for the gravity wave induced fluctuations in the intensity of airglow emissions and the associated temperature of the source region. The comparison is made in terms of Krassovsky's ratio eta(sub E) for a vertically extended emission region (eta(sub E) is the ratio of the vertically integrated normalized intensity perturbation to the vertically integrated intensity-weighted temperature perturbation). It is shown that the formulas for eta(sub E) in the works by Tarasick and Hines (1990) and Schubert et al. (1991) are in agreement for the case of an inviscid atmosphere. The calculation of eta(sub E) using the theory of Tarasick and Hines (1990) requires determination of their function chi; we show that chi is simply related to the 'single-level' Krassovsky's ratio eta of Schubert et al. (1991). The general relationship between chi and eta is applied to a simple chemical-dynamical model of the O2 atmospheric airglow and the altitude dependence of these quantities is evaluated for nonsteady state chemistry. Though the Tarasick and Hines (1990) formula for eta(sub E) does not explicitly depend on the scale heights of the minor constituents involved in airglow chemistry, eta(sub E) implicitly depends upon these scale heights through its dependences on chemical production and loss contained in chi. We demonstrate this dependence of eta(sub E) for the OH nightglow on atomic oxygen scale height by direct numerical evaluation of eta(sub E) in this case the dependence originates in the chemical production of perturbed ozone.

  20. Comparison of the genotoxic effects induced by 50 Hz extremely low-frequency electromagnetic fields and 1800 MHz radiofrequency electromagnetic fields in GC-2 cells.

    PubMed

    Duan, Weixia; Liu, Chuan; Zhang, Lei; He, Mindi; Xu, Shangcheng; Chen, Chunhai; Pi, Huifeng; Gao, Peng; Zhang, Yanwen; Zhong, Min; Yu, Zhengping; Zhou, Zhou

    2015-03-01

    Extremely low-frequency electromagnetic fields (ELF-EMF) and radiofrequency electromagnetic fields (RF-EMF) have been considered to be possibly carcinogenic to humans. However, their genotoxic effects remain controversial. To make experiments controllable and results comparable, we standardized exposure conditions and explored the potential genotoxicity of 50 Hz ELF-EMF and 1800 MHz RF-EMF. A mouse spermatocyte-derived GC-2 cell line was intermittently (5 min on and 10 min off) exposed to 50 Hz ELF-EMF at an intensity of 1, 2 or 3 mT or to RF-EMF in GSM-Talk mode at the specific absorption rates (SAR) of 1, 2 or 4 W/kg. After exposure for 24 h, we found that neither ELF-EMF nor RF-EMF affected cell viability using Cell Counting Kit-8. Through the use of an alkaline comet assay and immunofluorescence against γ-H2AX foci, we found that ELF-EMF exposure resulted in a significant increase of DNA strand breaks at 3 mT, whereas RF-EMF exposure had insufficient energy to induce such effects. Using a formamidopyrimidine DNA glycosylase (FPG)-modified alkaline comet assay, we observed that RF-EMF exposure significantly induced oxidative DNA base damage at a SAR value of 4 W/kg, whereas ELF-EMF exposure did not. Our results suggest that both ELF-EMF and RF-EMF under the same experimental conditions may produce genotoxicity at relative high intensities, but they create different patterns of DNA damage. Therefore, the potential mechanisms underlying the genotoxicity of different frequency electromagnetic fields may be different.

  1. Possible Ionospheric Electromagnetic Perturbations Induced by the Ms7.1 Yushu Earthquake

    NASA Astrophysics Data System (ADS)

    Zhima, Zeren; Xuhui, Shen; Xuemin, Zhang; Jinbin, Cao; Jianping, Huang; Xinyan, Ouyang; Jing, Liu; Lu, Bingqing

    2012-06-01

    The power spectrum density (PSD) of magnetic field in the ELF/VLF band recorded by the experiment IMSC onboard the DEMETER satellite were used to study the Ms7.1 Yushu earthquake taking place on April 13, 2010 in China. The results indicate that possible ionospheric electromagnetic perturbations occurring 4 days before the earthquake in the frequency range [370-897 Hz]. Along the orbit 30880_up, which passed over the epicenter area on 9 April, enhanced PSD value of magnetic field at 410 Hz was detected both over the epicentral area and its conjugate point in the southern hemisphere. While on revisited orbits during other days (before and after the earthquake) the magnetic field spectra remained at a relatively low level. In order to be sure that the electromagnetic disturbances were induced by this Yushu earthquake, relative variations of the magnetic field in the ELF/VLF range [370-897 Hz] were calculated and compared with the normal background during 3 years (2007, 2008 and 2009) in the time interval from Jan. 1st to Apr. 30 and in the area [23°N-43°N, 86°E-106°E]. The results show that the normal level of magnetic field in this area is relatively low (~10-7 nT2/Hz), but a large increase occurred from Apr. 1st to Apr. 14 which exceeds 5σb. After the earthquake, the magnetic field in the ELF/VLF range gradually decreased. In order to exclude the influence of geomagnetic field activity, we selected only the data recorded during magnetically quiet local night-times. In addition, artificial noises were also removed from the dataset used in the present paper. Therefore the observed perturbations were independent of geomagnetic field disturbances, and might be attributed to seismic activity.

  2. Electromagnetic millimeter wave induced hypoalgesia: frequency dependence and involvement of endogenous opioids.

    PubMed

    Radzievsky, A A; Gordiienko, O V; Alekseev, S; Szabo, I; Cowan, A; Ziskin, M C

    2008-05-01

    Millimeter wave treatment (MMWT) is based on the systemic biological effects that develop following local skin exposure to low power electromagnetic waves in the millimeter range. In the present set of experiments, the hypoalgesic effect of this treatment was analyzed in mice. The murine nose area was exposed to MMW of "therapeutic" frequencies: 42.25, 53.57, and 61.22 GHz. MMWT-induced hypoalgesia was shown to be frequency dependent in two experimental models: (1) the cold water tail-flick test (chronic non-neuropathic pain), and (2) the wire surface test (chronic neuropathic pain following unilateral constriction injury to the sciatic nerve). Maximum hypoalgesic effect was obtained when the frequency was 61.22 GHz. Other exposure parameters were: incident power density = 13.3 mW/cm(2), duration of each exposure = 15 min. Involvement of delta and kappa endogenous opioids in the MMWT-induced hypoalgesia was demonstrated using selective blockers of delta- and kappa-opioid receptors and the direct ELISA measurement of endogenous opioids in CNS tissue. Possible mechanisms of the effect and the perspectives of the clinical application of MMWT are discussed.

  3. Role of electromagnetically induced transparency in resonant four-wave-mixing schemes

    NASA Astrophysics Data System (ADS)

    Petch, J. C.; Keitel, C. H.; Knight, P. L.; Marangos, J. P.

    1996-01-01

    The effect of electromagnetically induced transparency in resonant four-wave-mixing schemes is investigated in an analysis that goes beyond perturbation theory in the coherent driving field. In addition we examine the case where the two-photon pump field is sufficiently strong to necessitate a nonperturbative treatment. This allows us to examine the cases where either one or both of the driving fields are strong. Phase matching is included in a plane-wave propagation treatment that matches the situation most likely to be encountered in actual experiments. The calculations are in part intended to model real experimental situations and thus incorporate driving and pump-field linewidths via the phase-diffusion model and Doppler broadening. With a strong pump-field laser, large enhancements in the efficiency of light generation occur at frequencies corresponding to the Autler-Townes satellites induced by the strong driving field. In this situation gain and high four-wave-mixing efficiency are simultaneously present, resulting in the production of a large intensity of coherent radiation.

  4. 18 GHz electromagnetic field induces permeability of Gram-positive cocci

    PubMed Central

    Nguyen, The Hong Phong; Shamis, Yury; Croft, Rodney J.; Wood, Andrew; McIntosh, Robert L.; Crawford, Russell J.; Ivanova, Elena P.

    2015-01-01

    The effect of electromagnetic field (EMF) exposures at the microwave (MW) frequency of 18 GHz, on four cocci, Planococcus maritimus KMM 3738, Staphylococcus aureus CIP 65.8T, S. aureus ATCC 25923 and S. epidermidis ATCC 14990T, was investigated. We demonstrate that exposing the bacteria to an EMF induced permeability in the bacterial membranes of all strains studied, as confirmed directly by transmission electron microscopy (TEM), and indirectly via the propidium iodide assay and the uptake of silica nanospheres. The cells remained permeable for at least nine minutes after EMF exposure. It was shown that all strains internalized 23.5 nm nanospheres, whereas the internalization of the 46.3 nm nanospheres differed amongst the bacterial strains (S. epidermidis ATCC 14990T~ 0%; Staphylococcus aureus CIP 65.8T S. aureus ATCC 25923, ~40%; Planococcus maritimus KMM 3738, ~80%). Cell viability experiments indicated that up to 84% of the cells exposed to the EMF remained viable. The morphology of the bacterial cells was not altered, as inferred from the scanning electron micrographs, however traces of leaked cytosolic fluids from the EMF exposed cells could be detected. EMF-induced permeabilization may represent an innovative, alternative cell permeability technique for applications in biomedical engineering, cell drug delivery and gene therapy. PMID:26077933

  5. Measurement of air-fluorescence-light yield induced by an electromagnetic shower

    NASA Astrophysics Data System (ADS)

    MACFLY Collaboration; Colin, P.; Chukanov, A.; Grebenyuk, V.; Naumov, D.; Nédélec, P.; Nefedov, Yu.; Onofre, A.; Porokhovoi, S.; Sabirov, B.; Tkatchev, L.

    2009-01-01

    For most of the ultra-high-energy cosmic ray (UHECR) experiments and projects (HiRes, AUGER, TA, JEM-EUSO, TUS, …), the detection technique of extensive air showers is based, at least, on the measurement of the air-fluorescence-induced signal. The knowledge of the fluorescence-light yield (FLY) is of paramount importance for the UHECR energy reconstruction. The MACFLY experiment was designed to perform absolute measurements of the air FLY and to study its properties. Here, we report the result of measurement of dry-air FLY induced by 50 GeV electromagnetic showers as a function of the shower age and as a function of the pressure. The experiment was performed at CERN using a SPS-electron-test-beam line. The result shows the air FLY is proportional to the energy deposited in air (Ed). The ratio FLY/Ed and its pressure dependence remain constant independently of shower age, and more generally, independently of the excitation source used (single-electron track or air shower).

  6. 18 GHz electromagnetic field induces permeability of Gram-positive cocci.

    PubMed

    Nguyen, The Hong Phong; Shamis, Yury; Croft, Rodney J; Wood, Andrew; McIntosh, Robert L; Crawford, Russell J; Ivanova, Elena P

    2015-06-16

    The effect of electromagnetic field (EMF) exposures at the microwave (MW) frequency of 18 GHz, on four cocci, Planococcus maritimus KMM 3738, Staphylococcus aureus CIP 65.8(T), S. aureus ATCC 25923 and S. epidermidis ATCC 14990(T), was investigated. We demonstrate that exposing the bacteria to an EMF induced permeability in the bacterial membranes of all strains studied, as confirmed directly by transmission electron microscopy (TEM), and indirectly via the propidium iodide assay and the uptake of silica nanospheres. The cells remained permeable for at least nine minutes after EMF exposure. It was shown that all strains internalized 23.5 nm nanospheres, whereas the internalization of the 46.3 nm nanospheres differed amongst the bacterial strains (S. epidermidis ATCC 14990(T) ~  0%; Staphylococcus aureus CIP 65.8(T) S. aureus ATCC 25923, ~40%; Planococcus maritimus KMM 3738, ~ 80%). Cell viability experiments indicated that up to 84% of the cells exposed to the EMF remained viable. The morphology of the bacterial cells was not altered, as inferred from the scanning electron micrographs, however traces of leaked cytosolic fluids from the EMF exposed cells could be detected. EMF-induced permeabilization may represent an innovative, alternative cell permeability technique for applications in biomedical engineering, cell drug delivery and gene therapy.

  7. 18 GHz electromagnetic field induces permeability of Gram-positive cocci.

    PubMed

    Nguyen, The Hong Phong; Shamis, Yury; Croft, Rodney J; Wood, Andrew; McIntosh, Robert L; Crawford, Russell J; Ivanova, Elena P

    2015-01-01

    The effect of electromagnetic field (EMF) exposures at the microwave (MW) frequency of 18 GHz, on four cocci, Planococcus maritimus KMM 3738, Staphylococcus aureus CIP 65.8(T), S. aureus ATCC 25923 and S. epidermidis ATCC 14990(T), was investigated. We demonstrate that exposing the bacteria to an EMF induced permeability in the bacterial membranes of all strains studied, as confirmed directly by transmission electron microscopy (TEM), and indirectly via the propidium iodide assay and the uptake of silica nanospheres. The cells remained permeable for at least nine minutes after EMF exposure. It was shown that all strains internalized 23.5 nm nanospheres, whereas the internalization of the 46.3 nm nanospheres differed amongst the bacterial strains (S. epidermidis ATCC 14990(T) ~  0%; Staphylococcus aureus CIP 65.8(T) S. aureus ATCC 25923, ~40%; Planococcus maritimus KMM 3738, ~ 80%). Cell viability experiments indicated that up to 84% of the cells exposed to the EMF remained viable. The morphology of the bacterial cells was not altered, as inferred from the scanning electron micrographs, however traces of leaked cytosolic fluids from the EMF exposed cells could be detected. EMF-induced permeabilization may represent an innovative, alternative cell permeability technique for applications in biomedical engineering, cell drug delivery and gene therapy. PMID:26077933

  8. Analysis of Numerical Simulation Database for Pressure Fluctuations Induced by High-Speed Turbulent Boundary Layers

    NASA Technical Reports Server (NTRS)

    Duan, Lian; Choudhari, Meelan M.

    2014-01-01

    Direct numerical simulations (DNS) of Mach 6 turbulent boundary layer with nominal freestream Mach number of 6 and Reynolds number of Re(sub T) approximately 460 are conducted at two wall temperatures (Tw/Tr = 0.25, 0.76) to investigate the generated pressure fluctuations and their dependence on wall temperature. Simulations indicate that the influence of wall temperature on pressure fluctuations is largely limited to the near-wall region, with the characteristics of wall-pressure fluctuations showing a strong temperature dependence. Wall temperature has little influence on the propagation speed of the freestream pressure signal. The freestream radiation intensity compares well between wall-temperature cases when normalized by the local wall shear; the propagation speed of the freestream pressure signal and the orientation of the radiation wave front show little dependence on the wall temperature.

  9. An observational study of MHD wave-induced density fluctuations upstream of the earth's bow shock

    NASA Technical Reports Server (NTRS)

    Spangler, Steven; Fey, Alan; Anderson, Gregory; Fuselier, Stephen

    1988-01-01

    An investigation of plasma density fluctations upstream of the earth's bow shock and their association with MHD waves is reported. The normalized density fluctuation was 14 percent on a day when the plasma beta was less than unity and the waves were circularly polarized and of relatively low amplitude, and 17 percent on a day when the plasma beta was in excess of unity and the waves were elliptically polarized and of large fractional amplitude. On both days there was a feature of the density power spectrum at the MHD carrier wave frequency attributable to oblique propagation of the waves with propagation angles of a few degrees with respect to the mean field. Ponderomotive effects due to spatial gradient in the MHD wave energy density are proposed as responsible for a correlation betweeen density and transverse wave intensity on both days. Generation of density fluctuations by linear polarized MHD waves is not an important contributor to the observed density fluctuations.

  10. Geographic variation in the flood-induced fluctuating temperature requirement for germination in Setaria parviflora seeds.

    PubMed

    Mollard, F P O; Insausti, P

    2011-07-01

    Our aim was to search for specific seed germinative strategies related to flooding escape in Setaria parviflora, a common species across the Americas. For this purpose, we investigated induction after floods, in relation to fluctuating temperature requirements for germination in seeds from mountain, floodplain and successional grasslands. A laboratory experiment was conducted in which seeds were imbibed or immersed in water at 5°C. Seeds were also buried in flood-prone and upland grasslands and exhumed during the flooding season. Additionally, seeds were buried in flooded or drained grassland mesocosms. Germination of exhumed seeds was assayed at 25°C or at 20°C/30°C in the dark or in the presence of red light pulses. After submergence or soil flooding, a high fraction (>32%) of seeds from the floodplain required fluctuating temperatures to germinate. In contrast, seeds from the mountains showed maximum differences in germination between fluctuating and constant temperature treatment only after imbibition (35%) or in non-flooded soil conditions (40%). The fluctuating temperature requirement was not clearly related to the foregoing conditions in the successional grassland seeds. Maximum germination could also be attained with red light pulses to seeds from mountain and successional grasslands. Results show that the fluctuating temperature requirement might help floodplain seeds to germinate after floods, indicating a unique feature of the dormancy of S. parviflora seeds from floodplains, which suggests an adaptive advantage aimed at postponing emergence during inundation periods. In contrast, the fluctuating temperature required for germination among seeds from mountain and successional grasslands show its importance for gap detection. PMID:21668607

  11. Analysis of the Radiated Field in an Electromagnetic Reverberation Chamber as an Upset-Inducing Stimulus for Digital Systems

    NASA Technical Reports Server (NTRS)

    Torres-Pomales, Wilfredo

    2012-01-01

    Preliminary data analysis for a physical fault injection experiment of a digital system exposed to High Intensity Radiated Fields (HIRF) in an electromagnetic reverberation chamber suggests a direct causal relation between the time profile of the field strength amplitude in the chamber and the severity of observed effects at the outputs of the radiated system. This report presents an analysis of the field strength modulation induced by the movement of the field stirrers in the reverberation chamber. The analysis is framed as a characterization of the discrete features of the field strength waveform responsible for the faults experienced by a radiated digital system. The results presented here will serve as a basis to refine the approach for a detailed analysis of HIRF-induced upsets observed during the radiation experiment. This work offers a novel perspective into the use of an electromagnetic reverberation chamber to generate upset-inducing stimuli for the study of fault effects in digital systems.

  12. Fluctuating plasma phosphorus level by changes in dietary phosphorus intake induces endothelial dysfunction.

    PubMed

    Watari, Eriko; Taketani, Yutaka; Kitamura, Tomoyo; Tanaka, Terumi; Ohminami, Hirokazu; Abuduli, Maerjianghan; Harada, Nagakatsu; Yamanaka-Okumura, Hisami; Yamamoto, Hironori; Takeda, Eiji

    2015-01-01

    High serum phosphorus (P) impairs endothelial function by increasing oxidative stress and decreasing nitric oxide production. Serum P levels fluctuate due to circadian rhythms or dietary P intake in healthy people and due to dialysis in end-stage chronic kidney disease patients. Here we examined whether fluctuating plasma P caused by changes in dietary P intake may be involved in endothelial dysfunction, resulting in increased cardiovascular risk. Rats were fed a diet containing 0.6% P for 16 days (control group), or a diet alternating between 0.02% P and 1.2% P (LH group) or between 1.2% P and 0.02% P (HL group) every 2 days; the total amount of P intake among the groups during the feeding period was similar. In the LH and HL groups, endothelial-dependent vasodilation significantly decreased plasma 8-(OH)dG level significantly increased, and the expression of inflammatory factors such as MCP-1 increased in the endothelium as compared with the control group. These data indicate that repetitive fluctuations of plasma P caused by varying dietary P intake can impair endothelial function via increased oxidative stress and inflammatory response. Taken together, these results suggest that habitual fluctuation of dietary P intake might be a cause of cardiovascular disease through endothelial dysfunction, especially in chronic kidney disease patients.

  13. Fluctuation-induced dielectric permittivity in the isotropic phase of cholesteric liquid crystals

    NASA Astrophysics Data System (ADS)

    Mukherjee, Prabir K.; Das, Asok K.

    2016-03-01

    The temperature and pressure dependence of the static dielectric permittivity in the isotropic phase of the isotropic to cholesteric phase transition is calculated using Landau-de Gennes’s fluctuation theory, allowing spatial variation of the orientational order parameter. A comparison is made with experimental data available in the isotropic phase of the isotropic to cholesteric phase transition.

  14. Fluctuating plasma phosphorus level by changes in dietary phosphorus intake induces endothelial dysfunction

    PubMed Central

    Watari, Eriko; Taketani, Yutaka; Kitamura, Tomoyo; Tanaka, Terumi; Ohminami, Hirokazu; Abuduli, Maerjianghan; Harada, Nagakatsu; Yamanaka-Okumura, Hisami; Yamamoto, Hironori; Takeda, Eiji

    2015-01-01

    High serum phosphorus (P) impairs endothelial function by increasing oxidative stress and decreasing nitric oxide production. Serum P levels fluctuate due to circadian rhythms or dietary P intake in healthy people and due to dialysis in end-stage chronic kidney disease patients. Here we examined whether fluctuating plasma P caused by changes in dietary P intake may be involved in endothelial dysfunction, resulting in increased cardiovascular risk. Rats were fed a diet containing 0.6% P for 16 days (control group), or a diet alternating between 0.02% P and 1.2% P (LH group) or between 1.2% P and 0.02% P (HL group) every 2 days; the total amount of P intake among the groups during the feeding period was similar. In the LH and HL groups, endothelial-dependent vasodilation significantly decreased plasma 8-(OH)dG level significantly increased, and the expression of inflammatory factors such as MCP-1 increased in the endothelium as compared with the control group. These data indicate that repetitive fluctuations of plasma P caused by varying dietary P intake can impair endothelial function via increased oxidative stress and inflammatory response. Taken together, these results suggest that habitual fluctuation of dietary P intake might be a cause of cardiovascular disease through endothelial dysfunction, especially in chronic kidney disease patients. PMID:25678749

  15. Respiratory-Induced Prostate Motion Using Wavelet Decomposition of the Real-Time Electromagnetic Tracking Signal

    SciTech Connect

    Lin, Yuting; Liu, Tian; Yang, Xiaofeng; Wang, Yuenan; Khan, Mohammad K.

    2013-10-01

    Purpose: The objective of this work is to characterize and quantify the impact of respiratory-induced prostate motion. Methods and Materials: Real-time intrafraction motion is observed with the Calypso 4-dimensional nonradioactive electromagnetic tracking system (Calypso Medical Technologies, Inc. Seattle, Washington). We report the results from a total of 1024 fractions from 31 prostate cancer patients. Wavelet transform was used to decompose the signal to extract and isolate the respiratory-induced prostate motion from the total prostate displacement. Results: Our results show that the average respiratory motion larger than 0.5 mm can be observed in 68% of the fractions. Fewer than 1% of the patients showed average respiratory motion of less than 0.2 mm, whereas 99% of the patients showed average respiratory-induced motion ranging between 0.2 and 2 mm. The maximum respiratory range of motion of 3 mm or greater was seen in only 25% of the fractions. In addition, about 2% patients showed anxiety, indicated by a breathing frequency above 24 times per minute. Conclusions: Prostate motion is influenced by respiration in most fractions. Real-time intrafraction data are sensitive enough to measure the impact of respiration by use of wavelet decomposition methods. Although the average respiratory amplitude observed in this study is small, this technique provides a tool that can be useful if one moves to smaller treatment margins (≤5 mm). This also opens ups the possibility of being able to develop patient specific margins, knowing that prostate motion is not unpredictable.

  16. Analogy of transistor function with modulating photonic band gap in electromagnetically induced grating.

    PubMed

    Wang, Zhiguo; Ullah, Zakir; Gao, Mengqin; Zhang, Dan; Zhang, Yiqi; Gao, Hong; Zhang, Yanpeng

    2015-09-09

    Optical transistor is a device used to amplify and switch optical signals. Many researchers focus on replacing current computer components with optical equivalents, resulting in an optical digital computer system processing binary data. Electronic transistor is the fundamental building block of modern electronic devices. To replace electronic components with optical ones, an equivalent optical transistor is required. Here we compare the behavior of an optical transistor with the reflection from a photonic band gap structure in an electromagnetically induced transparency medium. A control signal is used to modulate the photonic band gap structure. Power variation of the control signal is used to provide an analogy between the reflection behavior caused by modulating the photonic band gap structure and the shifting of Q-point (Operation point) as well as amplification function of optical transistor. By means of the control signal, the switching function of optical transistor has also been realized. Such experimental schemes could have potential applications in making optical diode and optical transistor used in quantum information processing.

  17. Polarized linewidth-controllable double-trapping electromagnetically induced transparency spectra in a resonant plasmon nanocavity

    PubMed Central

    Wang, Luojia; Gu, Ying; Chen, Hongyi; Zhang, Jia-Yu; Cui, Yiping; Gerardot, Brian D.; Gong, Qihuang

    2013-01-01

    Surface plasmons with ultrasmall optical mode volume and strong near field enhancement can be used to realize nanoscale light-matter interaction. Combining surface plasmons with the quantum system provides the possibility of nanoscale realization of important quantum optical phenomena, including the electromagnetically induced transparency (EIT), which has many applications in nonlinear quantum optics and quantum information processing. Here, using a custom-designed resonant plasmon nanocavity, we demonstrate polarized position-dependent linewidth-controllable EIT spectra at the nanoscale. We analytically obtain the double coherent population trapping conditions in a double-Λ quantum system with crossing damping, which give two transparent points in the EIT spectra. The linewidths of the three peaks are extremely sensitive to the level spacing of the excited states, the Rabi frequencies and detunings of pump fields, and the Purcell factors. In particular the linewidth of the central peak is exceptionally narrow. The hybrid system may have potential applications in ultra-compact plasmon-quantum devices. PMID:24096943

  18. Dressed-state electromagnetically induced transparency for light storage in uniform-phase spin waves

    NASA Astrophysics Data System (ADS)

    Šibalić, N.; Kondo, J. M.; Adams, C. S.; Weatherill, K. J.

    2016-09-01

    We present, experimentally and theoretically, a scheme for dressed-state electromagnetically induced transparency (EIT) in a three-step cascade system in which a four-level system is mapped into an effective three-level system. Theoretical analysis reveals that the scheme provides coherent-state control via adiabatic following and a generalized protocol for light storage in uniform phase spin-waves that are insensitive to motional dephasing. The three-step driving enables a number of other features, including spatial selectivity of the excitation region within the atomic medium, and kick-free and Doppler-free excitation that produces narrow resonances in thermal vapor. As a proof of concept, we present an experimental demonstration of the generalized EIT scheme using the 6 S1 /2→6 P3 /2→7 S1 /2→8 P1 /2 excitation path in thermal cesium vapor. This technique could be applied to cold and thermal ensembles to enable longer storage times for Rydberg polaritons.

  19. Controlled Electromagnetically Induced Transparency and Fano Resonances in Hybrid BEC-Optomechanics

    PubMed Central

    Yasir, Kashif Ammar; Liu, Wu-Ming

    2016-01-01

    Cavity-optomechanics, a tool to manipulate mechanical effects of light to couple optical field with other physical objects, is the subject of increasing investigations, especially with regards to electromagnetically induced transparency (EIT). EIT, a result of Fano interference among different atomic transition levels, has acquired a significant importance in many areas of physics, such as atomic physics and quantum optics. However, controllability of such multi-dimensional systems has remained a crucial issue. In this report, we investigate the controllability of EIT and Fano resonances in hybrid optomechanical system composed of cigar-shaped Bose-Einstein condensate (BEC), trapped inside high-finesse Fabry-Pérot cavity with one vibrational mirror, driven by a single mode optical field and a transverse pump field. The transverse field is used to control the phenomenon of EIT. It is detected that the strength of transverse field is not only efficiently amplifying or attenuating out-going optical mode but also providing an opportunity to enhance the strength of Fano-interactions which leads to the amplification of EIT-window. To observe these phenomena in laboratory, we suggest a certain set of experimental parameters. The results provide a route for tunable manipulation of optical phenomena, like EIT, which could be a significant step in quantum engineering. PMID:26955789

  20. Light storage based on four-wave mixing and electromagnetically induced transparency in cold atoms

    NASA Astrophysics Data System (ADS)

    Wu, Jinghui; Liu, Yang; Ding, Dong-Sheng; Zhou, Zhi-Yuan; Shi, Bao-Sen; Guo, Guang-Can

    2013-01-01

    We performed an experiment to observe the storage of an input probe field and an idler field generated through an off-axis four-wave mixing (FWM) process via a double-Λ configuration in a cold atomic ensemble. We analyzed the underlying physics in detail and found that the retrieved idler field came from two parts if there was no single-photon detuning for the pump pulse: Part 1 was from the collective atomic spin (the input probe field, the coupling field, and the pump field combined to generate the idler field through FWM; then the idler was stored through electromagnetically induced transparency). Part 2 was from the generated new FWM process during the retrieval process (the retrieved probe field, the coupling field, and the pump field combined to generate a new FWM signal). If there was single-photon detuning for the pump pulse, then the retrieved idler was mainly from part 2. The retrieved two fields exhibited damped oscillations with the same oscillatory period when a homogeneous external magnetic field was applied, which was caused by the Larmor spin precession. We also experimentally realized the storage and retrieval of an image of light using FWM, in which an image was added into the input signal. After the storage, the retrieved idler beams and input signal carried the same image. This image storage technique holds promise for applications in image processing, remote sensing, and quantum communication.

  1. Analogy of transistor function with modulating photonic band gap in electromagnetically induced grating

    NASA Astrophysics Data System (ADS)

    Wang, Zhiguo; Ullah, Zakir; Gao, Mengqin; Zhang, Dan; Zhang, Yiqi; Gao, Hong; Zhang, Yanpeng

    2015-09-01

    Optical transistor is a device used to amplify and switch optical signals. Many researchers focus on replacing current computer components with optical equivalents, resulting in an optical digital computer system processing binary data. Electronic transistor is the fundamental building block of modern electronic devices. To replace electronic components with optical ones, an equivalent optical transistor is required. Here we compare the behavior of an optical transistor with the reflection from a photonic band gap structure in an electromagnetically induced transparency medium. A control signal is used to modulate the photonic band gap structure. Power variation of the control signal is used to provide an analogy between the reflection behavior caused by modulating the photonic band gap structure and the shifting of Q-point (Operation point) as well as amplification function of optical transistor. By means of the control signal, the switching function of optical transistor has also been realized. Such experimental schemes could have potential applications in making optical diode and optical transistor used in quantum information processing.

  2. Density matrix reconstruction of three-level atoms via Rydberg electromagnetically induced transparency

    NASA Astrophysics Data System (ADS)

    Gavryusev, V.; Signoles, A.; Ferreira-Cao, M.; Zürn, G.; Hofmann, C. S.; Günter, G.; Schempp, H.; Robert-de-Saint-Vincent, M.; Whitlock, S.; Weidemüller, M.

    2016-08-01

    We present combined measurements of the spatially resolved optical spectrum and the total excited-atom number in an ultracold gas of three-level atoms under electromagnetically induced transparency conditions involving high-lying Rydberg states. The observed optical transmission of a weak probe laser at the center of the coupling region exhibits a double peaked spectrum as a function of detuning, while the Rydberg atom number shows a comparatively narrow single resonance. By imaging the transmitted light onto a charge-coupled-device camera, we record hundreds of spectra in parallel, which are used to map out the spatial profile of Rabi frequencies of the coupling laser. Using all the information available we can reconstruct the full one-body density matrix of the three-level system, which provides the optical susceptibility and the Rydberg density as a function of spatial position. These results help elucidate the connection between three-level interference phenomena, including the interplay of matter and light degrees of freedom and will facilitate new studies of many-body effects in optically driven Rydberg gases.

  3. Analogy of transistor function with modulating photonic band gap in electromagnetically induced grating

    PubMed Central

    Wang, Zhiguo; Ullah, Zakir; Gao, Mengqin; Zhang, Dan; Zhang, Yiqi; Gao, Hong; Zhang, Yanpeng

    2015-01-01

    Optical transistor is a device used to amplify and switch optical signals. Many researchers focus on replacing current computer components with optical equivalents, resulting in an optical digital computer system processing binary data. Electronic transistor is the fundamental building block of modern electronic devices. To replace electronic components with optical ones, an equivalent optical transistor is required. Here we compare the behavior of an optical transistor with the reflection from a photonic band gap structure in an electromagnetically induced transparency medium. A control signal is used to modulate the photonic band gap structure. Power variation of the control signal is used to provide an analogy between the reflection behavior caused by modulating the photonic band gap structure and the shifting of Q-point (Operation point) as well as amplification function of optical transistor. By means of the control signal, the switching function of optical transistor has also been realized. Such experimental schemes could have potential applications in making optical diode and optical transistor used in quantum information processing. PMID:26349444

  4. Ag induced electromagnetic interference shielding of Ag-graphite/PVDF flexible nanocomposites thinfilms

    SciTech Connect

    Kumaran, R.; Alagar, M.; Dinesh Kumar, S.; Subramanian, V.; Dinakaran, K.

    2015-09-14

    We report Ag nanoparticle induced Electromagnetic Interference (EMI) shielding in a flexible composite films of Ag nanoparticles incorporated graphite/poly-vinylidene difluoride (PVDF). PVDF nanocomposite thin-films were synthesized by intercalating Ag in Graphite (GIC) followed by dispersing GIC in PVDF. The X-ray diffraction analysis and the high-resolution transmission electron microscope clearly dictate the microstructure of silver nanoparticles in graphite intercalated composite of PVDF matrix. The conductivity values of nanocomposites are increased upto 2.5 times when compared to neat PVDF having a value of 2.70 S/cm at 1 MHz. The presence of Ag broadly enhanced the dielectric constant and lowers the dielectric loss of PVDF matrix proportional to Ag content. The EMI shielding effectiveness of the composites is 29.1 dB at 12.4 GHz for the sample having 5 wt. % Ag and 10 wt. % graphite in PVDF.

  5. Electromagnetically induced transparency with hybrid silicon-plasmonic traveling-wave resonators

    NASA Astrophysics Data System (ADS)

    Ketzaki, Dimitra A.; Tsilipakos, Odysseas; Yioultsis, Traianos V.; Kriezis, Emmanouil E.

    2013-09-01

    Spectral filtering and electromagnetically induced transparency (EIT) with hybrid silicon-plasmonic traveling-wave resonators are theoretically investigated. The rigorous three-dimensional vector finite element method simulations are complemented with temporal coupled mode theory. We show that ring and disk resonators with sub-micron radii can efficiently filter the lightwave with minimal insertion loss and high quality factors (Q). It is shown that disk resonators feature reduced radiation losses and are thus advantageous. They exhibit unloaded quality factors as high as 1000 in the telecom spectral range, resulting in all-pass filtering components with sharp resonances. By cascading two slightly detuned resonators and providing an additional route for resonator interaction (i.e., a second bus waveguide), a response reminiscent of EIT is observed. The EIT transmission peak can be shaped by means of resonator detuning and interelement separation. Importantly, the respective Q can become higher than that of the single-resonator structure. Thus, the possibility of exploiting this peak in switching applications relying on the thermo-optic effect is, finally, assessed.

  6. Energetic-particle-induced electromagnetic geodesic acoustic mode in tokamak plasmas

    NASA Astrophysics Data System (ADS)

    Wang, Lingfeng; Dong, J. Q.; He, Zhixiong; He, Hongda; Shen, Y.

    2014-07-01

    Energetic-particle-induced kinetic electromagnetic geodesic acoustic modes (EKEGAMs) are numerically studied in low β (=plasma pressure/magnetic pressure) tokamak plasmas. The parallel component of the perturbed vector potential is considered along with the electrostatic potential perturbation. The effects of finite Larmor radius and finite orbit width of the bulk and energetic ions as well as electron parallel dynamics are all taken into account in the dispersion relation. Systematic harmonic and ordering analysis are performed for frequency and growth rate spectra of the EKEGAMs, assuming ( k ρ i ) ˜ q - 3 ˜ β ≪ 1, where q, k, and ρi are the safety factor, radial component of the EKEGAMs wave vector, and the Larmor radius of the ions, respectively. It is found that there exist critical βh/βi values, which depend, in particular, on pitch angle of energetic ions and safety factor, for the mode to be driven unstable. The EKEGAMs may also be unstable for pitch angle λ 0 B < 0.4 in certain parameter regions. Finite β effect of the bulk ions is shown to have damping effect on the EKEGAMs. Modes with higher radial wave vectors have higher growth rates. The damping from electron dynamics is found decreasing with decrease of the temperature ratio Te/Ti. The modes are easily to be driven unstable in low safety factor q region and high temperature ratio Th/Ti region. The harmonic features of the EKEGAMs are discussed as well.

  7. Tunable electromagnetically induced transparency at terahertz frequencies in coupled graphene metamaterial

    NASA Astrophysics Data System (ADS)

    Ding, Guo-Wen; Liu, Shao-Bin; Zhang, Hai-Feng; Kong, Xiang-Kun; Li, Hai-Ming; Li, Bing-Xiang; Liu, Si-Yuan; Li, Hai

    2015-11-01

    A graphene-based metamaterial with tunable electromagnetically induced transparency (EIT)-like transmission is numerically studied in this paper. The proposed structure consists of a graphene layer composed of coupled cut-wire pairs printed on a substrate. The simulation confirms that an EIT-like transparency window can be observed due to indirect coupling in a terahertz frequency range. More importantly, the peak frequency of the transmission window can be dynamically controlled over a broad frequency range by varying the Fermi energy levels of the graphene layer through controlling the electrostatic gating. The proposed metamaterial structure offers an additional opportunity to design novel applications such as switches or modulators. Project supported by the National Natural Science Foundation of China (Grant No. 61307052), the Youth Funding for Science & Technology Innovation in Nanjing University of Aeronautics and Astronautics, China (Grant No. NS2014039), the Chinese Specialized Research Fund for the Doctoral Program of Higher Education (Grant No. 20123218110017), the Innovation Program for Graduate Education of Jiangsu Province, China (Grant Nos. KYLX_0272, CXZZ13_0166, and CXLX13_155), the Open Research Program in National State Key Laboratory of Millimeter Waves of China (Grant No. K201609), and the Fundamental Research Funds for the Central Universities of China (Grant No. kfjj20150407).

  8. Slow-light Airy wave packets and their active control via electromagnetically induced transparency

    NASA Astrophysics Data System (ADS)

    Hang, Chao; Huang, Guoxiang

    2013-07-01

    We propose a scheme to generate (3+1)-dimensional slow-light Airy wave packets in a resonant Λ-type three-level atomic gas via electromagnetically induced transparency. We show that in the absence of dispersion the Airy wave packets formed by a probe field consist of two Airy wave packets accelerated in transverse directions and a longitudinal Gaussian pulse with a constant propagating velocity lowered to 10-5c (c is the light speed in vacuum). We also show that in the presence of dispersion it is possible to generate another type of slow-light Airy wave packet consisting of two Airy beams in transverse directions and an Airy wave packet in the longitudinal direction. In this case, the longitudinal velocity of the Airy wave packet can be further reduced during propagation. Additionally, we further show that the transverse accelerations (or bending) of the both types of slow-light Airy wave packets can be completely eliminated and the motional trajectories of them can be actively manipulated and controlled by using a Stern-Gerlach gradient magnetic field.

  9. Three-dimensional forward calculation of the electromagnetic fields induced by tsunamis

    NASA Astrophysics Data System (ADS)

    Utada, H.; Zhang, L.; Shimizu, H.; Baba, K.; Maeda, T.

    2012-12-01

    The motion of seawater induces electromotive force of significant intensity (Sanford, 1971) due to Faraday's law, and resulting electromagnetic (EM) field can be recorded by instruments installed on land or at ocean bottom (Tyler, 2005; Toh et al. 2011). However, only a few studies were successfully simulating Tsunami induced EM fields by an exact and accurate application of Maxwell equations that is essential for a quantitative interpretation to get geophysical information from observations of tsunami-related EM signals. There are a number of observations of such EM fields that were caused by the devastating Tohoku tsunami of 2011 not only on land observatories but also at some seafloor sites (e.g. Utada et al., 2011; Ichihara et al., 2012). Here we present a 3-D modeling scheme to simulate these observed fields. We apply a 3-D EM induction code in Cartesian coordinate system with the heterogeneous source term, which is based on the modified iterative dissipative method (MIDM) (Zhang et al. 2012), and several underground electrical conductivity structures were assumed in the calculations. The source current distribution is predicted by the flow data calculated by a tsunami simulation (Maeda and Furumura, 2011) which solves Navier-Stokes equations in 3-D Cartesian coordinates. In our previous study (Utada et al., 2011), we estimated tsunami-induced fields by applying Biot-Savart law to the same set of flow data and obtained qualitative agreement between observations on land and model results. However quantitatively, we noticed that the present result generally gives smaller amplitude than the result of Biot-Savart calculation. This can be ascribed to the EM induction effect in the sea. We also tried some underground structures, but the effect of the underground structure is negligible compared with that of the induction in the sea. Meanwhile, we found that the effect of the source current by the vertical motion, which was ignored in the previous study, can be

  10. Structure-fluctuation-induced abnormal thermoelectric properties in semiconductor copper selenide

    SciTech Connect

    Liu, Huili; Shi, Xun; Kirkham, Melanie J; Wang, Hsin; Li, Qiang; Uher, Ctirad; Zhang, Wenqing; Chen, Lidong

    2013-01-01

    Thermoelectric effects and related technologies have attracted a great interest due to the world-wide energy harvesting. Thermoelectricity has usually been considered in the context of stable material phases. Here we report that the fluctuation of structures during the second-order phase transition in Cu2Se semiconductor breaks the conventional trends of thermoelectric transports in normal phases, leading to a critically phase-transition-enhanced thermoelectric figure of merit zT above unity at 400K, a three times larger value than for the normal phases. Dynamic structural transformations introduce intensive fluctuations and extreme complexity, which enhance the carrier entropy and thus the thermopower, and strongly scatter carriers and phonons as well to make their transports behave critically.

  11. Deformation-induced spatiotemporal fluctuation, evolution and localization of strain fields in a bulk metallic glass

    DOE PAGESBeta

    Wu, Yuan; Bei, Hongbin; Wang, Yanli; Lu, Zhaoping; George, Easo P.; Gao, Yanfei

    2015-05-16

    Deformation behavior and local strain evolutions upon loading and unloading of a bulk metallic glass (BMG) were systematically investigated by in situ digital image correlation (DIC). Distinct fluctuations and irreversible local strains were observed before the onset of macroscopic yielding. Statistical analysis shows that these fluctuations might be related to intrinsic structural heterogeneities, and that the evolution history and characteristics of local strain fields play an important role in the subsequent initiation of shear bands. Effects of sample size, pre-strain, and loading conditions were systematically analyzed in terms of the probability distributions of the resulting local strain fields. It ismore » found that a higher degree of local shear strain heterogeneity corresponds to a more ductile stressestrain curve. Implications of these findings are discussed for the design of new materials.« less

  12. Deformation-induced spatiotemporal fluctuation, evolution and localization of strain fields in a bulk metallic glass

    SciTech Connect

    Wu, Yuan; Bei, Hongbin; Wang, Yanli; Lu, Zhaoping; George, Easo P.; Gao, Yanfei

    2015-05-16

    Deformation behavior and local strain evolutions upon loading and unloading of a bulk metallic glass (BMG) were systematically investigated by in situ digital image correlation (DIC). Distinct fluctuations and irreversible local strains were observed before the onset of macroscopic yielding. Statistical analysis shows that these fluctuations might be related to intrinsic structural heterogeneities, and that the evolution history and characteristics of local strain fields play an important role in the subsequent initiation of shear bands. Effects of sample size, pre-strain, and loading conditions were systematically analyzed in terms of the probability distributions of the resulting local strain fields. It is found that a higher degree of local shear strain heterogeneity corresponds to a more ductile stressestrain curve. Implications of these findings are discussed for the design of new materials.

  13. Homotopy Perturbation Method-Based Analytical Solution for Tide-Induced Groundwater Fluctuations.

    PubMed

    Munusamy, Selva Balaji; Dhar, Anirban

    2016-05-01

    The groundwater variations in unconfined aquifers are governed by the nonlinear Boussinesq's equation. Analytical solution for groundwater fluctuations in coastal aquifers under tidal forcing can be solved using perturbation methods. However, the perturbation parameters should be properly selected and predefined for traditional perturbation methods. In this study, a new dimensional, higher-order analytical solution for groundwater fluctuations is proposed by using the homotopy perturbation method with a virtual perturbation parameter. Parameter-expansion method is used to remove the secular terms generated during the solution process. The solution does not require any predefined perturbation parameter and valid for higher values of amplitude parameter A/D, where A is the amplitude of the tide and D is the aquifer thickness.

  14. Computational Investigation of Block Copolymer Surfactants for Stabilizing Fluctuation-Induced Polymeric Microemulsions

    NASA Astrophysics Data System (ADS)

    Delaney, Kris; Fredrickson, Glenn

    2013-03-01

    High molecular weight diblock copolymers introduced into a blend of immiscible homopolymers can act as a surfactant to suppress macroscopic two-fluid phase separation. With variation of block copolymer composition, the crossover between low-temperature ordering into microphase or macrophase separated states is marked by a mean-field isotropic Lifshitz multi-critical point. Strong fluctuations close to the Lifshitz point are observed to suppress the low-temperature ordering; a microemulsion state emerges, with large, co-continuous domains of segregated fluid lacking any long-range order. We study this phenomenon with fully fluctuating field-theoretic simulations based on complex Langevin sampling, and we attempt to design new block polymer surfactants that can produce the microemulsion state with a wider composition tolerance.

  15. Piston slap induced pressure fluctuation in the water coolant passage of an internal combustion engine

    NASA Astrophysics Data System (ADS)

    Ohta, Kazuhide; Wang, Xiaoyu; Saeki, Atsushi

    2016-02-01

    Liner cavitation is caused by water pressure fluctuation in the water coolant passage (WCP). When the negative pressure falls below the saturated vapor pressure, the impulsive pressure following the implosion of cavitation bubbles causes cavitation erosion of the wet cylinder liner surface. The present work establishes a numerical model for structural-acoustic coupling between the crankcase and the acoustic field in the WCP considering their dynamic characteristics. The coupling effect is evaluated through mutual interaction terms that are calculated from the mode shapes of the acoustic field and of the crankcase vibration on the boundary. Water pressure fluctuations in the WCP under the action of piston slap forces are predicted and the contributions of the uncoupled mode shapes of the crankcase and the acoustic field to the pressure waveform are analyzed. The influence of sound speed variations on the water pressure response is discussed, as well as the pressure on the thrust sides of the four cylinders.

  16. Precipitation-Induced Voltage-Dependent Ion Current Fluctuations in Conical Nanopores

    SciTech Connect

    Vlassiouk, Ivan V

    2010-01-01

    Single conically shaped nanopores produce stable ion current fluctuations when in contact with weakly soluble salts, such as calcium hydrogen phosphate (CaHPO{sub 4}) and cobalt hydrogen phosphate (CoHPO{sub 4}). The pore spontaneously switches between high and low conductance states, called open and closed states, respectively. Pore opening and closing are linked to the dynamic formation of the calcium and cobalt precipitates at the small opening of the pore. The probabilities of pore opening and closing are voltage-dependent, and this characteristic of ion current signal is known for biological voltage-gated channels. We show that new types of ion current fluctuations are obtained in conditions at which precipitates of CaHPO{sub 4} and CoHPO{sub 4} can form in the pore at the same time.

  17. Model for fluctuating inflaton coupling: sneutrino induced adiabatic perturbations and nonthermal leptogenesis.

    PubMed

    Mazumdar, Anupam

    2004-06-18

    We discuss a unique possibility of generating adiabatic density perturbations and leptogenesis from the spatial fluctuations of the inflaton decay rate. The key assumption is that the initial isocurvature perturbations are created in the right-handed sneutrino sector during inflation which is then converted into adiabatic perturbations when the inflaton decays. We discuss distinct imprints on the cosmic microwave background radiation, which can distinguish nonthermal versus thermal leptogenesis.

  18. Linear and nonlinear coupling of electromagnetic and electrostatic fluctuations with one dimensional trapping of electrons using product bi (r,q) distribution

    NASA Astrophysics Data System (ADS)

    Aziz, Tahir; Masood, W.; Qureshi, M. N. S.; Shah, H. A.; Yoon, P. H.

    2016-06-01

    In the present paper, we have investigated the ramifications of adiabatic trapping of electrons using a bi product ( r , q ) distribution function on obliquely propagating Alfven waves in a low β plasma. In this regard, we have analyzed the linear and nonlinear dispersion characteristics of finite amplitude coupled kinetic Alfven-acoustic solitary waves using the two-potential theory and employing Sagdeev potential approach. We have deliberated upon the results of the present inquest and highlighted its importance by citing works that have reported the simultaneous presence of electromagnetic pulses and flat-topped distribution of electrons.

  19. Field models and numerical dosimetry inside an extremely-low-frequency electromagnetic bioreactor: the theoretical link between the electromagnetically induced mechanical forces and the biological mechanisms of the cell tensegrity.

    PubMed

    Mognaschi, Maria Evelina; Di Barba, Paolo; Magenes, Giovanni; Lenzi, Andrea; Naro, Fabio; Fassina, Lorenzo

    2014-01-01

    We have implemented field models and performed a detailed numerical dosimetry inside our extremely-low-frequency electromagnetic bioreactor which has been successfully used in in vitro Biotechnology and Tissue Engineering researches. The numerical dosimetry permitted to map the magnetic induction field (maximum module equal to about 3.3 mT) and to discuss its biological effects in terms of induced electric currents and induced mechanical forces (compression and traction). So, in the frame of the tensegrity-mechanotransduction theory of Ingber, the study of these electromagnetically induced mechanical forces could be, in our opinion, a powerful tool to understand some effects of the electromagnetic stimulation whose mechanisms remain still elusive. PMID:25202652

  20. Spatial mobility fluctuation induced giant linear magnetoresistance in multilayered graphene foam

    NASA Astrophysics Data System (ADS)

    Li, Peng; Zhang, Qiang; He, Xin; Ren, Wencai; Cheng, Hui-Ming; Zhang, Xi-xiang

    2016-07-01

    Giant, positive, and near-temperature-independent linear magnetoresistance (LMR), as large as 340%, was observed in graphene foam with a three-dimensional flexible network. Careful analysis of the magnetoresistance revealed that Shubnikov-de Haas (SdH) oscillations occurred at low temperatures and decayed with increasing temperature. The average classical mobility ranged from 300 (2 K) to 150 (300 K) c m2V-1s-1 , which is much smaller than that required by the observed SdH oscillations. To understand the mechanism behind the observation, we performed the same measurements on the microsized graphene sheets that constitute the graphene foam. Much more pronounced SdH oscillations superimposed on the LMR background were observed in these microscaled samples, which correspond to a quantum mobility as high as 26 ,500 c m2V-1s-1 . Moreover, the spatial mobility fluctuated significantly from 64 ,200 c m2V-1s-1 to 1370 c m2V-1s-1 , accompanied by a variation of magnetoresistance from near 20,000% to less than 20%. The presence of SdH oscillations actually excludes the possibility that the observed LMR originated from the extreme quantum limit, because this would demand all electrons to be in the first Landau level. Instead, we ascribe the large LMR to the second case of the classical Parish and Littlewood model, in which spatial mobility fluctuation dominates electrical transport. This is an experimental confirmation of the Parish and Littlewood model by measuring the local mobility randomly (by measuring the microsized graphene sheets) and finding the spatial mobility fluctuation.

  1. Flow-induced agitations create a granular fluid: Effective viscosity and fluctuations

    NASA Astrophysics Data System (ADS)

    Nichol, Kiri; van Hecke, Martin

    2012-06-01

    We fluidize a granular medium with localized stirring in a split-bottom shear cell. We probe the mechanical response of quiescent regions far from the main flow by observing the vertical motion of cylindrical probes rising, sinking, and floating in the grains. First, we find that the probe motion suggests that the granular material behaves in a liquid-like manner: high-density probes sink and low-density probes float at the depth given by Archimedes’ law. Second, we observe that the drag force on moving probes scales linearly with their velocity, which allows us to define an effective viscosity for the system. This effective viscosity is inversely proportional to the rotation rate of the disk which drives the split bottom flow. Moreover, the apparent viscosity depends on radius and mass of the probe: despite the linear dependence of the drag forces on sinking speed of the probe, the granular medium is not simply Newtonian, but exhibits a more complex rheology. The decrease of viscosity with filling height of the cell, combined with the poor correlation between local strain rate and viscosity, suggests that the fluid-like character of the material is set by agitations generated in the stirred region: the relation between applied stress and observed strain rate in one location depends on the strain rate in another location. We probe the nature of the granular fluctuations that we believe mediates these nonlocal interactions by characterizing the small and random up and down motion that the probe experiences. These Gaussian fluctuations exhibit a mix of diffusive and subdiffusive behavior at short times and saturate at a value of roughly 1/10th of a grain diameter longer times, consistent with the picture of a random walker in a potential well. The product of crossover time and effective viscosity is constant, evidencing a direct link between fluctuations and viscosity.

  2. Fluctuation-Induced Forces Between Inclusions in a Fluid Membrane Under Tension

    NASA Astrophysics Data System (ADS)

    Lin, Hsiang-Ku; Zandi, Roya; Mohideen, Umar; Pryadko, Leonid P.

    2011-11-01

    We develop an exact method to calculate thermal Casimir forces between inclusions of arbitrary shapes and separation, embedded in a fluid membrane whose fluctuations are governed by the combined action of surface tension, bending modulus, and Gaussian rigidity. Each object’s shape and mechanical properties enter only through a characteristic matrix, a static analog of the scattering matrix. We calculate the Casimir interaction between two elastic disks embedded in a membrane. In particular, we find that at short separations the interaction is strong and independent of surface tension.

  3. Fluctuation-induced forces between inclusions in a fluid membrane under tension.

    PubMed

    Lin, Hsiang-Ku; Zandi, Roya; Mohideen, Umar; Pryadko, Leonid P

    2011-11-25

    We develop an exact method to calculate thermal Casimir forces between inclusions of arbitrary shapes and separation, embedded in a fluid membrane whose fluctuations are governed by the combined action of surface tension, bending modulus, and Gaussian rigidity. Each object's shape and mechanical properties enter only through a characteristic matrix, a static analog of the scattering matrix. We calculate the Casimir interaction between two elastic disks embedded in a membrane. In particular, we find that at short separations the interaction is strong and independent of surface tension.

  4. Feasibility of measuring temperature and density fluctuations in air using laser-induced O2 fluorescence

    NASA Technical Reports Server (NTRS)

    Massey, G. A.; Lemon, C. J.

    1984-01-01

    A tunable line-narrowed ArF laser can selectively excite several rotation al lines of the Schumann-Runge band system of O2 in air. The resulting ultraviolet fluorescence can be monitored at 90 deg to the laser beam axis, permitting space and time resolved observation of density and temperature fluctuations in turbulence. Experiments and calculations show that + or - 1 K, + or - 1 percent density, 1 cu mm spatial, and 1 microsecond temporal resolution can be achieved simultaneously under some conditions.

  5. Combined effects of flow-induced shear stress and electromagnetic field on neural differentiation of mesenchymal stem cells.

    PubMed

    Mascotte-Cruz, Juan Uriel; Ríos, Amelia; Escalante, Bruno

    2016-01-01

    Differentiation of bone marrow-derived mesenchymal stem cells (MSCs) into neural phenotype has been induced by either flow-induced shear stress (FSS) or electromagnetic fields (EMF). However, procedures are still expensive and time consuming. In the present work, induction for 1 h with the combination of both forces showed the presence of the neural precursor nestin as early as 9 h in culture after treatment and this result lasted for the following 6 d. In conclusion, the use of a combination of FSS and EMF for a short-time renders in neurite-like cells, although further investigation is required to analyze cell functionality.

  6. Lightning induced inappropriate ICD shock: an unusual case of electromagnetic interference.

    PubMed

    Anderson, Daniel R; Gillberg, Jeffrey M; Torrey, Jeffrey W; Koneru, Jayanthi N

    2012-06-01

    An unusual case of electromagnetic interference is presented. As a result of a lightning shock to a Shower House, our patient received two shocks. An elucidation of the different mechanisms for the two shocks is presented.

  7. Directivity of a Sparse Array in the Presence of Atmospheric-Induced Phase Fluctuations for Deep Space Communications

    NASA Technical Reports Server (NTRS)

    Nessel, James A.; Acosta, Robert J.

    2010-01-01

    Widely distributed (sparse) ground-based arrays have been utilized for decades in the radio science community for imaging celestial objects, but have only recently become an option for deep space communications applications with the advent of the proposed Next Generation Deep Space Network (DSN) array. But whereas in astronomical imaging, observations (receive-mode only) are made on the order of minutes to hours and atmospheric-induced aberrations can be mostly corrected for in post-processing, communications applications require transmit capabilities and real-time corrections over time scales as short as fractions of a second. This presents an unavoidable problem with the use of sparse arrays for deep space communications at Ka-band which has yet to be successfully resolved, particularly for uplink arraying. In this paper, an analysis of the performance of a sparse antenna array, in terms of its directivity, is performed to derive a closed form solution to the expected array loss in the presence of atmospheric-induced phase fluctuations. The theoretical derivation for array directivity degradation is validated with interferometric measurements for a two-element array taken at Goldstone, California. With the validity of the model established, an arbitrary 27-element array geometry is defined at Goldstone, California, to ascertain its performance in the presence of phase fluctuations. It is concluded that a combination of compact array geometry and atmospheric compensation is necessary to ensure high levels of availability.

  8. Numerical study on the partitioning of the molecular polarizability into fluctuating charge and induced atomic dipole contributions.

    PubMed

    Mei, Ye; Simmonett, Andrew C; Pickard, Frank C; DiStasio, Robert A; Brooks, Bernard R; Shao, Yihan

    2015-06-01

    In order to carry out a detailed analysis of the molecular static polarizability, which is the response of the molecule to a uniform external electric field, the molecular polarizability was computed using the finite-difference method for 21 small molecules, using density functional theory. Within nine charge population schemes (Löwdin, Mulliken, Becke, Hirshfeld, CM5, Hirshfeld-I, NPA, CHELPG, MK-ESP) in common use, the charge fluctuation contribution is found to dominate the molecular polarizability, with its ratio ranging from 59.9% with the Hirshfeld or CM5 scheme to 96.2% with the Mulliken scheme. The Hirshfeld-I scheme is also used to compute the other contribution to the molecular polarizability coming from the induced atomic dipoles, and the atomic polarizabilities in eight small molecules and water pentamer are found to be highly anisotropic for most atoms. Overall, the results suggest that (a) more emphasis probably should be placed on the charge fluctuation terms in future polarizable force field development and (b) an anisotropic polarizability might be more suitable than an isotropic one in polarizable force fields based entirely or partially on the induced atomic dipoles.

  9. Numerical Study on the Partitioning of the Molecular Polarizability into Fluctuating Charge and Induced Atomic Dipole Contributions

    PubMed Central

    Mei, Ye; Simmonett, Andrew C.; Pickard, Frank C.; DiStasio, Robert A.; Brooks, Bernard R.; Shao, Yihan

    2015-01-01

    In order to carry out a detailed analysis of the molecular static polarizability, which is the response of the molecule to a uniform external electric field, the molecular polarizability was computed using the finite-difference method for 21 small molecules, using density functional theory. Within nine charge population schemes (Löwdin, Mulliken, Becke, Hirshfeld, CM5, Hirshfeld-I, NPA, CHELPG, MK-ESP) in common use, the charge fluctuation contribution is found to dominate the molecular polarizability, with its ratio ranging from 59.9% with the Hirshfeld or CM5 scheme to 96.2% with the Mulliken scheme. The Hirshfeld-I scheme is also used to compute the other contribution to the molecular polarizability coming from the induced atomic dipoles, and the atomic polarizabilities in 8 small molecules and water pentamer are found to be highly anisotropic for most atoms. Overall, the results suggest that (a) more emphasis probably should be placed on the charge fluctuation terms in future polarizable force field development; (b) an anisotropic polarizability might be more suitable than an isotropic one in polarizable force fields based entirely or partially on the induced atomic dipoles. PMID:25945749

  10. Impact of random discrete dopant in extension induced fluctuation in gate-source/drain underlap FinFET

    NASA Astrophysics Data System (ADS)

    Wang, Yijiao; Huang, Peng; Xin, Zheng; Zeng, Lang; Liu, Xiaoyan; Du, Gang; Kang, Jinfeng

    2014-01-01

    In this work, three dimensional technology computer-aided design (TCAD) simulations are performed to investigate the impact of random discrete dopant (RDD) including extension induced fluctuation in 14 nm silicon-on-insulator (SOI) gate-source/drain (G-S/D) underlap fin field effect transistor (FinFET). To fully understand the RDD impact in extension, RDD effect is evaluated in channel and extension separately and together. The statistical variability of FinFET performance parameters including threshold voltage (Vth), subthreshold slope (SS), drain induced barrier lowering (DIBL), drive current (Ion), and leakage current (Ioff) are analyzed. The results indicate that RDD in extension can lead to substantial variability, especially for SS, DIBL, and Ion and should be taken into account together with that in channel to get an accurate estimation on RDF. Meanwhile, higher doping concentration of extension region is suggested from the perspective of overall variability control.

  11. The radioprotective effects of Moringa oleifera against mobile phone electromagnetic radiation-induced infertility in rats

    PubMed Central

    Bin-Meferij, Mashael Mohammed; El-kott, Attalla Farag

    2015-01-01

    The present study has investigated the effects of mobile phone electromagnetic radiation (EMR) on fertility in rats. The purpose of this study was to explore the capability of polyphenolic-rich Moringa oleifera leaf extract in protecting rat testis against EMR-induced impairments based on evaluation of sperm count, viability, motility, sperm cell morphology, anti-oxidants (SOD & CAT), oxidative stress marker, testis tissue histopathology and PCNA immunohistochemistry. The sample consisted of sixty male Wistar rats which were divided into four equal groups. The first group (the control) received only standard diet while the second group was supplemented daily and for eight weeks with 200 mg/kg aqueous extract of Moringa leaves. The third group was exposed to 900 MHz fields for one hour a day and for (7) days a week. As for the fourth group, it was exposed to mobile phone radiation and received the Moringa extract. The results showed that the EMR treated group exhibited a significantly decrease sperm parameters. Furthermore, concurrent exposure to EMR and treated with MOE significantly enhanced the sperm parameters. However, histological results in EMR group showed irregular seminiferous tubules, few spermatogonia, giant multinucleated cells, degenerated spermatozoa and the number of Leydig cells was significantly reduced. PCNA labeling indices were significant in EMR group versus the control group. Also, EMR affects spermatogenesis and causes to apoptosis due to the heat and other stress-related EMR in testis tissue. This study concludes that chronic exposure to EMR marked testicular injury which can be prevented by Moringa oleifera leaf extract. PMID:26550159

  12. Short-pulse cross-phase modulation in an electromagnetically-induced-transparency medium

    NASA Astrophysics Data System (ADS)

    Feizpour, Amir; Dmochowski, Greg; Steinberg, Aephraim M.

    2016-01-01

    Electromagnetically induced transparency (EIT) has been proposed as a way to greatly enhance cross-phase modulation, with the possibility of leading to few-photon-level optical nonlinearities [Schmidt and Imamoglu, Opt. Lett. 21, 1936 (1996), 10.1364/OL.21.001936]. This enhancement grows as the transparency window width, ΔEIT, is narrowed. Decreasing ΔEIT, however, has been shown to increase the response time of the nonlinear medium. This suggests that, for a given pulse duration, the nonlinearity would diminish once the window width became narrower than this pulse bandwidth. We show that this is not the case: the peak phase shift saturates but does not decrease. We show that in the regimes of most practical interest—narrow EIT windows perturbed by short signal pulses—the enhancement offered by EIT is not only in the magnitude of the nonlinear phase shift but also in its increased duration. That is, for the case of signal pulses much shorter (temporally) than the inverse EIT bandwidth, the narrow window serves to prolong the effect of the passing signal pulse, leading to an integrated phase shift that grows linearly with 1 /ΔEIT ; this continued growth of the integrated phase shift improves the detectability of the phase shift, in principle, without bound. For many purposes, it is this detectability which is of more interest than the absolute magnitude of the peak phase shift. We present analytical expressions based on a linear time-invariant model that accounts for the temporal behavior of the cross-phase modulation for several parameter ranges of interest. We conclude that in order to optimize the detectability of the EIT-based cross-phase shift, one should use the narrowest possible EIT window and a signal pulse that is as broadband as the excited-state linewidth and detuned by half a linewidth.

  13. The radioprotective effects of Moringa oleifera against mobile phone electromagnetic radiation-induced infertility in rats.

    PubMed

    Bin-Meferij, Mashael Mohammed; El-Kott, Attalla Farag

    2015-01-01

    The present study has investigated the effects of mobile phone electromagnetic radiation (EMR) on fertility in rats. The purpose of this study was to explore the capability of polyphenolic-rich Moringa oleifera leaf extract in protecting rat testis against EMR-induced impairments based on evaluation of sperm count, viability, motility, sperm cell morphology, anti-oxidants (SOD & CAT), oxidative stress marker, testis tissue histopathology and PCNA immunohistochemistry. The sample consisted of sixty male Wistar rats which were divided into four equal groups. The first group (the control) received only standard diet while the second group was supplemented daily and for eight weeks with 200 mg/kg aqueous extract of Moringa leaves. The third group was exposed to 900 MHz fields for one hour a day and for (7) days a week. As for the fourth group, it was exposed to mobile phone radiation and received the Moringa extract. The results showed that the EMR treated group exhibited a significantly decrease sperm parameters. Furthermore, concurrent exposure to EMR and treated with MOE significantly enhanced the sperm parameters. However, histological results in EMR group showed irregular seminiferous tubules, few spermatogonia, giant multinucleated cells, degenerated spermatozoa and the number of Leydig cells was significantly reduced. PCNA labeling indices were significant in EMR group versus the control group. Also, EMR affects spermatogenesis and causes to apoptosis due to the heat and other stress-related EMR in testis tissue. This study concludes that chronic exposure to EMR marked testicular injury which can be prevented by Moringa oleifera leaf extract.

  14. The radioprotective effects of Moringa oleifera against mobile phone electromagnetic radiation-induced infertility in rats.

    PubMed

    Bin-Meferij, Mashael Mohammed; El-Kott, Attalla Farag

    2015-01-01

    The present study has investigated the effects of mobile phone electromagnetic radiation (EMR) on fertility in rats. The purpose of this study was to explore the capability of polyphenolic-rich Moringa oleifera leaf extract in protecting rat testis against EMR-induced impairments based on evaluation of sperm count, viability, motility, sperm cell morphology, anti-oxidants (SOD & CAT), oxidative stress marker, testis tissue histopathology and PCNA immunohistochemistry. The sample consisted of sixty male Wistar rats which were divided into four equal groups. The first group (the control) received only standard diet while the second group was supplemented daily and for eight weeks with 200 mg/kg aqueous extract of Moringa leaves. The third group was exposed to 900 MHz fields for one hour a day and for (7) days a week. As for the fourth group, it was exposed to mobile phone radiation and received the Moringa extract. The results showed that the EMR treated group exhibited a significantly decrease sperm parameters. Furthermore, concurrent exposure to EMR and treated with MOE significantly enhanced the sperm parameters. However, histological results in EMR group showed irregular seminiferous tubules, few spermatogonia, giant multinucleated cells, degenerated spermatozoa and the number of Leydig cells was significantly reduced. PCNA labeling indices were significant in EMR group versus the control group. Also, EMR affects spermatogenesis and causes to apoptosis due to the heat and other stress-related EMR in testis tissue. This study concludes that chronic exposure to EMR marked testicular injury which can be prevented by Moringa oleifera leaf extract. PMID:26550159

  15. Barometric and tidal-induced aquifer water level fluctuation near the Ariake Sea.

    PubMed

    Dong, Linyao; Shimada, Jun; Kagabu, Makoto; Yang, Heejun

    2015-01-01

    Observations of water levels in coastal aquifers and corresponding tides coupled with meteorological variances near the Ariake Sea show that groundwater in this area mainly fluctuates with atmospheric and tidal variations. Tidal effects occur with semi-monthly, diurnal, or semi-diurnal periodicity, whereas the barometric influences commonly act in the low-frequency domain. Tidal and barometric effects in water levels are separable using wavelet techniques and can be evaluated statistically. Results show the following. (1) The tidal coefficients are 0.002-0.154, attenuating roughly exponentially from the seashore. The time lags in water levels increase linearly approximately with increasing inshore distance. Relations between tidal coefficients and time lags and the inshore distance indicate higher hydraulic diffusivity in the south aquifer, which was confirmed by the hydraulic property calibrations in analytical simulations. (2) Water levels related to meteorological phenomena fluctuate inversely according to barometric loading variation with time lags of 2-3 h. The effective barometric efficiencies are 0.022-0.12. Lower barometric influences were found in the south aquifer.

  16. Barometric and tidal-induced aquifer water level fluctuation near the Ariake Sea.

    PubMed

    Dong, Linyao; Shimada, Jun; Kagabu, Makoto; Yang, Heejun

    2015-01-01

    Observations of water levels in coastal aquifers and corresponding tides coupled with meteorological variances near the Ariake Sea show that groundwater in this area mainly fluctuates with atmospheric and tidal variations. Tidal effects occur with semi-monthly, diurnal, or semi-diurnal periodicity, whereas the barometric influences commonly act in the low-frequency domain. Tidal and barometric effects in water levels are separable using wavelet techniques and can be evaluated statistically. Results show the following. (1) The tidal coefficients are 0.002-0.154, attenuating roughly exponentially from the seashore. The time lags in water levels increase linearly approximately with increasing inshore distance. Relations between tidal coefficients and time lags and the inshore distance indicate higher hydraulic diffusivity in the south aquifer, which was confirmed by the hydraulic property calibrations in analytical simulations. (2) Water levels related to meteorological phenomena fluctuate inversely according to barometric loading variation with time lags of 2-3 h. The effective barometric efficiencies are 0.022-0.12. Lower barometric influences were found in the south aquifer. PMID:25467417

  17. Increase in the Random Dopant Induced Threshold Fluctuations and Lowering in Sub 100 nm MOSFETs Due to Quantum Effects: A 3-D Density-Gradient Simulation Study

    NASA Technical Reports Server (NTRS)

    Asenov, Asen; Slavcheva, G.; Brown, A. R.; Davies, J. H.; Saini, S.

    2000-01-01

    In this paper we present a detailed simulation study of the influence of quantum mechanical effects in the inversion layer on random dopant induced threshold voltage fluctuations and lowering in sub 100 nm MOSFETs. The simulations have been performed using a 3-D implementation of the density gradient (DG) formalism incorporated in our established 3-D atomistic simulation approach. This results in a self-consistent 3-D quantum mechanical picture, which implies not only the vertical inversion layer quantisation but also the lateral confinement effects related to current filamentation in the 'valleys' of the random potential fluctuations. We have shown that the net result of including quantum mechanical effects, while considering statistical dopant fluctuations, is an increase in both threshold voltage fluctuations and lowering. At the same time, the random dopant induced threshold voltage lowering partially compensates for the quantum mechanical threshold voltage shift in aggressively scaled MOSFETs with ultrathin gate oxides.

  18. Analysis of the damage threshold of the GaAs pseudomorphic high electron mobility transistor induced by the electromagnetic pulse

    NASA Astrophysics Data System (ADS)

    Xi, Xiao-Wen; Chai, Chang-Chun; Liu, Yang; Yang, Yin-Tang; Fan, Qing-Yang; Shi, Chun-Lei

    2016-08-01

    An electromagnetic pulse (EMP)-induced damage model based on the internal damage mechanism of the GaAs pseudomorphic high electron mobility transistor (PHEMT) is established in this paper. With this model, the relationships among the damage power, damage energy, pulse width and signal amplitude are investigated. Simulation results show that the pulse width index from the damage power formula obtained here is higher than that from the empirical formula due to the hotspot transferring in the damage process of the device. It is observed that the damage energy is not a constant, which decreases with the signal amplitude increasing, and then changes little when the signal amplitude reaches up to a certain level. Project supported by the National Basic Research Program of China (Grant No. 2014CB339900) and the Open Fund of Key Laboratory of Complex Electromagnetic Environment Science and Technology, China Academy of Engineering Physics (CAEP) (Grant No. 2015-0214.XY.K).

  19. Plasma Density and Electro-Magnetic Field Perturbations Hf-Induced in the Outer Ionosphere: Review of Experimental Results

    NASA Astrophysics Data System (ADS)

    Frolov, Vladimir; Rauch, Jean-Louis; Parrot, Michel; Rapoport, Victor; Shorokhova, Elena

    In the report we consider features of plasma density and electro-magnetic field perturbations induced in the Earth’s outer ionosphere by modification of F _{2} region by O-mode powerful HF radio waves radiated by the SURA heating facility. Experiments presented were carried out in 2005 - 2010. Plasma density perturbations were detected at altitudes of about of 700 km by instruments onboard the French DEMETER satellite when it intersected the disturbed magnetic flux tube. The formation of artificial HF-induced plasma density ducts in the outer ionosphere is a central discovery, which was made during the SURA-DEMETER experiments [1,2]. Analysis of experimental data available makes it possible to formulate ducts features and point out the conditions under which the formation of such ducts takes place. 1. Under night conditions ducts are characterized by the increased plasma density in the range from 20% to 80% relatively to its background value. As this takes place, the excess in the plasma ion component is due to O (+) ions dominating at altitudes of about 700 km, whereas the densities of lower mass H (+) and He ({+) } ions typically decrease by a percentage amount that is much more the relative increase in the density of O (+) ions. The duct formation was never observed under daytime conditions. According to [3] the HF-induced ducts were observed by ionosphere pumping in morning and evening hours but in these cases their intensity was no more than a few percentages. 2. The size of the ducts along the satellite orbits is of about 80 - 100 km. It is a reason why such ducts can be observed only if the minimal distance between the satellite and the center of the heated flux tube is less than 50 km. 3. The formation of ducts is observed only if the effective radiated power is more than 40 MW. For the SURA facility, to heat the ionosphere at higher efficiency due to the “magnetic-zenith effect”, the HF beam is often inclined by 12 - 16(°) southward. 4. The pump

  20. Cholesterol-induced suppression of membrane elastic fluctuations at the atomistic level.

    PubMed

    Molugu, Trivikram R; Brown, Michael F

    2016-09-01

    Applications of solid-state NMR spectroscopy for investigating the influences of lipid-cholesterol interactions on membrane fluctuations are reviewed in this paper. Emphasis is placed on understanding the energy landscapes and fluctuations at an emergent atomistic level. Solid-state (2)H NMR spectroscopy directly measures residual quadrupolar couplings (RQCs) due to individual C-(2)H labeled segments of the lipid molecules. Moreover, residual dipolar couplings (RDCs) of (13)C-(1)H bonds are obtained in separated local-field NMR spectroscopy. The distributions of RQC or RDC values give nearly complete profiles of the order parameters as a function of acyl segment position. Measured equilibrium properties of glycerophospholipids and sphingolipids including their binary and tertiary mixtures with cholesterol show unequal mixing associated with liquid-ordered domains. The entropic loss upon addition of cholesterol to sphingolipids is less than for glycerophospholipids and may drive the formation of lipid rafts. In addition relaxation time measurements enable one to study the molecular dynamics over a wide time-scale range. For (2)H NMR the experimental spin-lattice (R1Z) relaxation rates follow a theoretical square-law dependence on segmental order parameters (SCD) due to collective slow dynamics over mesoscopic length scales. The functional dependence for the liquid-crystalline lipid membranes is indicative of viscoelastic properties as they emerge from atomistic-level interactions. A striking decrease in square-law slope upon addition of cholesterol denotes stiffening relative to the pure lipid bilayers that is diminished in the case of lanosterol. Measured equilibrium properties and relaxation rates infer opposite influences of cholesterol and detergents on collective dynamics and elasticity at an atomistic scale that potentially affects lipid raft formation in cellular membranes. PMID:27154600

  1. Suppression of insolation heating induced by electromagnetic scatteringdue to fine spheres

    NASA Astrophysics Data System (ADS)

    Horie, J.; Mikada, H.; Goto, T.; Takekawa, J.; Manaka, Y.; Taniguchi, K.; Ashida, Y.

    2013-12-01

    The 2011 off the Pacific coast of Tohoku Earthquake, i.e., the greatest earthquake in the Japanese history, and the successive disaster at the Fukushima Daiichi Nuclear Power Plant have caused a fatal electric power shortage problem in summer in 2011. It is of key importance to reduce electricity demand and to save the energy. About one third of the total electricity demand at the peak consumption in summer is for the air-conditioning in the household and office sectors in Japan. It is, therefore, necessary to think deliberately of the reduction of electric power demand for air-conditioning. In fact, the temperature of materials rises when they are exposed to the sunlight (insolation heating) in particular in summer and the air-conditioning would become necessary for restoring the comfort in insolated housings. The energy for the air-conditioning is spent to pump out the heat changed in the materials of the insolated housings and would be proportional to the temperature to lower down. It is, therefore, clear that the reduction of the energy for the air-conditioning would strongly depend on relaxation of temperature rise or the insulation of insolated materials. Insolation heating could be suppressed when the materials are coated with paint admixed with fine silica spheres (insulating paint). By coating buildings' walls and roofs with such paint, the temperature of interior rooms could be kept lower without air-conditioning. These insulation effects are well known and have been utilized in the past, but have hardly been analyzed theoretically yet. Theoretical analysis would greatly enhance the effects of the suppression of insolation heating. In preceding studies, Ohkawa et al.(2009; 2011) and Mikada et al.(2011) focused on the electromagnetic wave scattering induced by fine spheres and developed the analytical method using superposition of scattered waves from each sphere (the first Born approximation), and indicated that the size of the spheres is one of the

  2. Terahertz electromagnetic fields (0.106 THz) do not induce manifest genomic damage in vitro.

    PubMed

    Hintzsche, Henning; Jastrow, Christian; Kleine-Ostmann, Thomas; Kärst, Uwe; Schrader, Thorsten; Stopper, Helga

    2012-01-01

    Terahertz electromagnetic fields are non-ionizing electromagnetic fields in the frequency range from 0.1 to 10 THz. Potential applications of these electromagnetic fields include the whole body scanners, which currently apply millimeter waves just below the terahertz range, but future scanners will use higher frequencies in the terahertz range. These and other applications will bring along human exposure to these fields. Up to now, only a limited number of investigations on biological effects of terahertz electromagnetic fields have been performed. Therefore, research is strongly needed to enable reliable risk assessment.Cells were exposed for 2 h, 8 h, and 24 h with different power intensities ranging from 0.04 mW/cm(2) to 2 mW/cm(2), representing levels below, at, and above current safety limits. Genomic damage on the chromosomal level was measured as micronucleus formation. DNA strand breaks and alkali-labile sites were quantified with the comet assay. No DNA strand breaks or alkali-labile sites were observed as a consequence of exposure to terahertz electromagnetic fields in the comet assay. The fields did not cause chromosomal damage in the form of micronucleus induction.

  3. Terahertz Electromagnetic Fields (0.106 THz) Do Not Induce Manifest Genomic Damage In Vitro

    PubMed Central

    Hintzsche, Henning; Jastrow, Christian; Kleine-Ostmann, Thomas; Kärst, Uwe; Schrader, Thorsten; Stopper, Helga

    2012-01-01

    Terahertz electromagnetic fields are non-ionizing electromagnetic fields in the frequency range from 0.1 to 10 THz. Potential applications of these electromagnetic fields include the whole body scanners, which currently apply millimeter waves just below the terahertz range, but future scanners will use higher frequencies in the terahertz range. These and other applications will bring along human exposure to these fields. Up to now, only a limited number of investigations on biological effects of terahertz electromagnetic fields have been performed. Therefore, research is strongly needed to enable reliable risk assessment. Cells were exposed for 2 h, 8 h, and 24 h with different power intensities ranging from 0.04 mW/cm2 to 2 mW/cm2, representing levels below, at, and above current safety limits. Genomic damage on the chromosomal level was measured as micronucleus formation. DNA strand breaks and alkali-labile sites were quantified with the comet assay. No DNA strand breaks or alkali-labile sites were observed as a consequence of exposure to terahertz electromagnetic fields in the comet assay. The fields did not cause chromosomal damage in the form of micronucleus induction. PMID:23029508

  4. Potential protection of green tea polyphenols against 1800 MHz electromagnetic radiation-induced injury on rat cortical neurons.

    PubMed

    Liu, Mei-Li; Wen, Jian-Qiang; Fan, Yu-Bo

    2011-10-01

    Radiofrequency electromagnetic fields (EMF) are harmful to public health, but the certain anti-irradiation mechanism is not clear yet. The present study was performed to investigate the possible protective effects of green tea polyphenols against electromagnetic radiation-induced injury in the cultured rat cortical neurons. In this study, green tea polyphenols were used in the cultured cortical neurons exposed to 1800 MHz EMFs by the mobile phone. We found that the mobile phone irradiation for 24 h induced marked neuronal cell death in the MTT (3-(4,5-dimethylthiazole-2-yl)-2,5-diphenyl-tetrazolium bromide) and TUNEL (TdT mediated biotin-dUTP nicked-end labeling) assay, and protective effects of green tea polyphenols on the injured cortical neurons were demonstrated by testing the content of Bcl-2 Assaciated X protein (Bax) in the immunoprecipitation assay and Western blot assay. In our study results, the mobile phone irradiation-induced increases in the content of active Bax were inhibited significantly by green tea polyphenols, while the contents of total Bax had no marked changes after the treatment of green tea polyphenols. Our results suggested a neuroprotective effect of green tea polyphenols against the mobile phone irradiation-induced injury on the cultured rat cortical neurons.

  5. Seismic wave attenuation and dispersion due to wave-induced fluid flow in rocks with strong permeability fluctuations.

    PubMed

    Germán Rubino, J; Monachesi, Leonardo B; Müller, Tobias M; Guarracino, Luis; Holliger, Klaus

    2013-12-01

    Oscillatory fluid movements in heterogeneous porous rocks induced by seismic waves cause dissipation of wave field energy. The resulting seismic signature depends not only on the rock compressibility distribution, but also on a statistically averaged permeability. This so-called equivalent seismic permeability does not, however, coincide with the respective equivalent flow permeability. While this issue has been analyzed for one-dimensional (1D) media, the corresponding two-dimensional (2D) and three-dimensional (3D) cases remain unexplored. In this work, this topic is analyzed for 2D random medium realizations having strong permeability fluctuations. With this objective, oscillatory compressibility simulations based on the quasi-static poroelasticity equations are performed. Numerical analysis shows that strong permeability fluctuations diminish the magnitude of attenuation and velocity dispersion due to fluid flow, while the frequency range where these effects are significant gets broader. By comparing the acoustic responses obtained using different permeability averages, it is also shown that at very low frequencies the equivalent seismic permeability is similar to the equivalent flow permeability, while for very high frequencies this parameter approaches the arithmetic average of the permeability field. These seemingly generic findings have potentially important implications with regard to the estimation of equivalent flow permeability from seismic data. PMID:25669286

  6. Seismic wave attenuation and dispersion due to wave-induced fluid flow in rocks with strong permeability fluctuations.

    PubMed

    Germán Rubino, J; Monachesi, Leonardo B; Müller, Tobias M; Guarracino, Luis; Holliger, Klaus

    2013-12-01

    Oscillatory fluid movements in heterogeneous porous rocks induced by seismic waves cause dissipation of wave field energy. The resulting seismic signature depends not only on the rock compressibility distribution, but also on a statistically averaged permeability. This so-called equivalent seismic permeability does not, however, coincide with the respective equivalent flow permeability. While this issue has been analyzed for one-dimensional (1D) media, the corresponding two-dimensional (2D) and three-dimensional (3D) cases remain unexplored. In this work, this topic is analyzed for 2D random medium realizations having strong permeability fluctuations. With this objective, oscillatory compressibility simulations based on the quasi-static poroelasticity equations are performed. Numerical analysis shows that strong permeability fluctuations diminish the magnitude of attenuation and velocity dispersion due to fluid flow, while the frequency range where these effects are significant gets broader. By comparing the acoustic responses obtained using different permeability averages, it is also shown that at very low frequencies the equivalent seismic permeability is similar to the equivalent flow permeability, while for very high frequencies this parameter approaches the arithmetic average of the permeability field. These seemingly generic findings have potentially important implications with regard to the estimation of equivalent flow permeability from seismic data.

  7. Chronic exposure to environmental stressors induces fluctuating asymmetry in shrews inhabiting protected Mediterranean sites.

    PubMed

    Sánchez-Chardi, Alejandro; García-Pando, Marián; López-Fuster, María José

    2013-10-01

    Many ecotoxicological studies have addressed the effects of contaminant exposure at various levels of biological organization. However, little information exists on the effects of toxicants on wildlife populations. Here we examined exposure of populations of the greater white-toothed shrew Crocidura russula (Soricomorpha, Soricidae) occupying two protected Mediterranean sites (a polluted area, the Ebro Delta, and a control site, Garraf Massif). Bioaccumulation of selected elements (Pb, Hg, Cd, Zn, Cu, Fe, Mn, Cr, Mo, Sr, Ba, and B), a body condition index (BCI) and fluctuating asymmetry (FA) were used to assess the chronic exposure to environmental pollution. BCI was correlated neither to metal concentrations nor to FA, suggesting that this fitness measure only reflects environmental disturbances at a local level. However, shrews from the polluted area showed higher concentrations of metals and metalloids (Pb, Hg, B, and Sr) and greater shape FA than specimens from the reference area. A correlation between FA was found for both first and second principal component vectors suggesting that developmental instability increases as a result of exposure to multiple pollutants. Our results corroborate the suitability of C. russula as a bioindicator of environmental quality and show that FA is an appropriate index to examine impact of developmental stressors in populations inhabiting disturbed areas.

  8. Shear-induced force fluctuations and acoustic emissions in granular material

    NASA Astrophysics Data System (ADS)

    Michlmayr, Gernot; Cohen, Denis; Or, Dani

    2013-12-01

    We conducted a series of strain-controlled experiments to study the characteristics of a shear zone forming in dense flow of confined dry granular media. The primary objective was to link force fluctuations due to jamming and force network reformation with episodic release of elastic energy as passively monitored by acoustic emission sensors. Under constant deformation rate, the shear stress exhibits a characteristic sawtooth behavior reflecting the strong influence of micromechanical processes on the macroscopic stress-strain behavior. Measured shear stress jumps were highly correlated with low-frequency (< 20 kHz) acoustic emission events. High-frequency (30 kHz-80 kHz) acoustic signals that were measured with different sensors appear to be directly linked to continual grain-scale interactions (e.g., friction, rolling). A conceptual mechanical fiber bundle model (FBM) was used to represent dynamics at the shear zone of large granular assemblies. The model was capable of reproducing the dynamics of stress jumps and associated elastic energy release events. The combination of acoustic emission (AE) measurements and FBM framework offers new insights into the behavior of shear failure and enhances capabilities for resolving grain-scale mechanical processes and for predicting rapid mass movement such as shallow landslides and debris flows.

  9. Cholesterol-induced variations in the volume and enthalpy fluctuations of lipid bilayers.

    PubMed

    Halstenberg, S; Heimburg, T; Hianik, T; Kaatze, U; Krivanek, R

    1998-07-01

    The sound velocity and density of suspensions of large unilamellar liposomes from dimyristoylphosphatidylcholine with admixed cholesterol have been measured as a function of temperature around the chain melting temperature of the phospholipid. The cholesterol-to-phospholipid molar ratio xc has been varied over a wide range (0 fluctuations within the samples. A theoretical relation between the compressibility and the excess heat capacity of the bilayer system has been derived. Comparison of the compressibilities (and sound velocity numbers) with heat capacity traces display the close correlation between these quantities for bilayer systems. This correlation appears to be very useful as it allows some of the mechanical properties of membrane systems to be calculated from the specific heat capacity data and vice versa. PMID:9649386

  10. Synchronization transitions induced by the fluctuation of adaptive coupling strength in delayed Newman-Watts neuronal networks.

    PubMed

    Wang, Qi; Gong, Yubing; Wu, Yanan

    2015-11-01

    Introducing adaptive coupling in delayed neuronal networks and regulating the dissipative parameter (DP) of adaptive coupling by noise, we study the effect of fluctuations of the changing rate of adaptive coupling on the synchronization of the neuronal networks. It is found that time delay can induce synchronization transitions for intermediate DP values, and the synchronization transitions become strongest when DP is optimal. As the intensity of DP noise is varied, the neurons can also exhibit synchronization transitions, and the phenomenon is delay-dependent and is enhanced for certain time delays. Moreover, the synchronization transitions change with the change of DP and become strongest when DP is optimal. These results show that randomly changing adaptive coupling can considerably change the synchronization of the neuronal networks, and hence could play a crucial role in the information processing and transmission in neural systems.

  11. Detection of discrete surface charge dynamics in GaAs-based nanowire through metal-tip-induced current fluctuation

    NASA Astrophysics Data System (ADS)

    Sato, Masaki; Yin, Xiang; Kuroda, Ryota; Kasai, Seiya

    2016-02-01

    We investigated the detection of discrete charge dynamics of an electron trap in a GaAs-based nanowire surface through current fluctuation induced by a metallic scanning probe tip. An equivalent circuit model indicated that the charge state in the surface strongly reflects the channel potential when the local surface potential is fixed by the metal tip, which suggests that random charging and discharging dynamics of the trap appears as random telegraph signal (RTS) noise in the nanowire current. Experimental demonstration of the concept was carried out using a GaAs-based nanowire and an atomic force microscope (AFM) system with a conductive tip. We observed the RTS noise in the drain current and superposition of the Lorentzian component in the noise spectrum when the metal tip was in contact with the nanowire surface at specific positions. The obtained results indicate the possibility of detecting charge dynamics of the individual surface trap in semiconductor devices.

  12. Particle modelling of low-pressure radio-frequency magnetron discharges including the effects of self-induced electromagnetic fields

    NASA Astrophysics Data System (ADS)

    Benyoucef, D.; Yousfi, M.

    2014-08-01

    Modelling of radio-frequency (RF) magnetron discharges is performed using a particle-in-cell/Monte Carlo technique in the case of low-pressure argon gas at 4 mTorr and high external magnetic field in order to self-maintain the discharge and to generate an energetic quasi-ion beam required for cathode sputtering applications. An emphasis is made, for the first time in the literature in the case of low-pressure RF discharges, on the development of a particle model coupled with the full set of electromagnetic field equations. The aim is to analyse the effect on the RF plasma features of the plasma-induced magnetic field resulting from the coupling of the Maxwell-Ampere equation. We also analysed the effect of the electric field due to the time variation of magnetic field resulting from the coupling of the Maxwell-Faraday equation. For the present asymmetrical plasma reactor, the mean relative difference on, for instance, the ion density with and without the consideration of plasma-induced magnetic and electric fields due to the time variation of the magnetic field can reach about 2.5% in the region of the plasma bulk and about 10% in the lateral sheath. The effects of these two induced electromagnetic fields are in fact higher in the regions where the radial magnetic field generated by the external magnets belonging to the magnetron configuration is low. These non-negligible relative differences clearly show the importance of rigorously taking into account, beyond the usual Poisson's equation for the space charge electric field, the full set of electromagnetic Maxwell equations for a more accurate modelling of these low-pressure discharges, particularly when the total current density reaches a few mA cm-2.

  13. The structure of electromagnetic wave-induced 557.7-nm emission associated with a sporadic- E event over arecibo

    PubMed

    Kagan; Kelley; Garcia; Bernhardt; Djuth; Sulzer; Tepley

    2000-07-01

    We report observations of electromagnetic wave-induced 557.7-nm emission in correspondence with a sporadic low-altitude plasma layer (the sporadic- E layer, E(s)). We show that the structure of 557. 7-nm emission seen for some events results from a transformation of transmitted energy by ionization clouds, compiling the patchy type E(s), and presents a projection of the sporadic- E layer structure on the emission altitude. This allows us to propose the first method for visualizing a horizontal structure of sporadic- E layers. PMID:10991198

  14. The structure of electromagnetic wave-induced 557.7-nm emission associated with a sporadic- E event over arecibo

    PubMed

    Kagan; Kelley; Garcia; Bernhardt; Djuth; Sulzer; Tepley

    2000-07-01

    We report observations of electromagnetic wave-induced 557.7-nm emission in correspondence with a sporadic low-altitude plasma layer (the sporadic- E layer, E(s)). We show that the structure of 557. 7-nm emission seen for some events results from a transformation of transmitted energy by ionization clouds, compiling the patchy type E(s), and presents a projection of the sporadic- E layer structure on the emission altitude. This allows us to propose the first method for visualizing a horizontal structure of sporadic- E layers.

  15. Propagation of a probe pulse inside a Bose-Einstein condensate under conditions of electromagnetically induced transparency

    NASA Astrophysics Data System (ADS)

    Barberis-Blostein, Pablo; Aguilar-Loreto, Omar

    2015-06-01

    We obtain a partial differential equation for a pulse travelling inside a Bose-Einstein condensate under conditions of electromagnetically induced transparency. The equation is valid for a weak probe pulse. We solve the equation for the case of a three-level BEC in Λ configuration with one of its ground state spatial profiles initially constant. The solution characterizes, in detail, the effect that the evolution of the condensate wave function has on pulse propagation, including the process of stopping and releasing it.

  16. Electromagnetically induced transparency and lasing without inversion in three-level atoms imbedded in a frequency-dependent environment

    NASA Astrophysics Data System (ADS)

    Radeonychev, Y. V.; Erukhimova, M. A.; Kocharovskaya, O. A.; Vilaseca, R.

    2004-10-01

    The response of a three-level atomic system driven by a resonant coherent field acting on a transition near the photonic band-edge of a photonic band-gap material as well as the general case of a frequency-dependent reservoir is studied. The strong frequency dependence of the radiation mode spectral density on the scale of the driving field Rabi frequency is shown to lead to essential and controllable changes in the refractive index, as well as to effects of electromagnetically induced transparency and lasing without inversion. Such an effective dynamic control of the atomic response enables for applications in nonlinear optics and optical computing and communications.

  17. Chemotherapy Drug Induced Discoordination of Mitochondrial Life Cycle Detected by Cardiolipin Fluctuation

    PubMed Central

    Chao, Yu-Jen; Chan, Jui-Fen; Hsu, Yuan-Hao Howard

    2016-01-01

    Chemotherapy drugs have been prescribed for the systemic treatment of cancer. We selected three chemotherapy drugs, including methotrexate, mitomycine C and vincristine to inhibit the proliferation of HT1080 human fibrosarcoma cells in S, G2 and M phases of the cell cycle respectively. These chemotherapy drugs showed significant toxicity and growth inhibition to the cancer cells measured by MTT assay. After treated with a 50% inhibitory dosage for 48 hours, these cancer cells showed significant accumulation of cardiolipin (CL), which was a reverse trend of the nutritional deficiency induced arrest at G1 phase. The quantity of each CL species was further semi-quantitated by HPLC-ion trap mass spectrometer. Methotraxate treatment caused unique increases of acyl chain length on CL, which were the opposite of the serum starvation, mitomycine C and vincristine treatments. Although mitomycine C and vincristine have different mechanisms to induce cell cycle arrest, these two drugs displayed similar effects on decreasing chain length of CL. Continuation of CL synthesis during cell cycle arrest indicated the chemotherapy drugs resulting in the discoordination of the mitochondrial life cycle from the cell cycle and thus caused the accumulation of CL. These finding reveals that the pre-remodeling nascent CL accumulates during the methotraxate induced arrest; however, the post-remodeling mature CL accumulates during the mitomycine C and vincristine induced arrest after the synthesis phase. PMID:27627658

  18. Chemotherapy Drug Induced Discoordination of Mitochondrial Life Cycle Detected by Cardiolipin Fluctuation.

    PubMed

    Chao, Yu-Jen; Chan, Jui-Fen; Hsu, Yuan-Hao Howard

    2016-01-01

    Chemotherapy drugs have been prescribed for the systemic treatment of cancer. We selected three chemotherapy drugs, including methotrexate, mitomycine C and vincristine to inhibit the proliferation of HT1080 human fibrosarcoma cells in S, G2 and M phases of the cell cycle respectively. These chemotherapy drugs showed significant toxicity and growth inhibition to the cancer cells measured by MTT assay. After treated with a 50% inhibitory dosage for 48 hours, these cancer cells showed significant accumulation of cardiolipin (CL), which was a reverse trend of the nutritional deficiency induced arrest at G1 phase. The quantity of each CL species was further semi-quantitated by HPLC-ion trap mass spectrometer. Methotraxate treatment caused unique increases of acyl chain length on CL, which were the opposite of the serum starvation, mitomycine C and vincristine treatments. Although mitomycine C and vincristine have different mechanisms to induce cell cycle arrest, these two drugs displayed similar effects on decreasing chain length of CL. Continuation of CL synthesis during cell cycle arrest indicated the chemotherapy drugs resulting in the discoordination of the mitochondrial life cycle from the cell cycle and thus caused the accumulation of CL. These finding reveals that the pre-remodeling nascent CL accumulates during the methotraxate induced arrest; however, the post-remodeling mature CL accumulates during the mitomycine C and vincristine induced arrest after the synthesis phase. PMID:27627658

  19. Cold induces micro- and nano-scale reorganization of lipid raft markers at mounds of T-cell membrane fluctuations.

    PubMed

    Chen, Yong; Qin, Jie; Cai, Jiye; Chen, Zheng W

    2009-01-01

    Whether and how cold causes changes in cell-membrane or lipid rafts remain poorly characterized. Using the NSOM/QD and confocal imaging systems, we found that cold caused microscale redistribution of lipid raft markers, GM1 for lipid and CD59 for protein, from the peripheral part of microdomains to the central part on Jurkat T cells, and that cold also induced the nanoscale size-enlargement (1/3- to 2/3-fold) of the nanoclusters of lipid raft markers and even the colocalization of GM1 and CD59 nanoclusters. These findings indicate cold-induced lateral rearrangement/coalescence of raft-related membrane heterogeneity. The cold-induced re-distribution of lipid raft markers under a nearly-natural condition provide clues for their alternations, and help to propose a model in which raft lipids associate themselves or interact with protein components to generate functional membrane heterogeneity in response to stimulus. The data also underscore the possible cold-induced artifacts in early-described cold-related experiments and the detergent-resistance-based analyses of lipid rafts at 4 degrees C, and provide a biophysical explanation for recently-reported cold-induced activation of signaling pathways in T cells. Importantly, our fluorescence-topographic NSOM imaging demonstrated that GM1/CD59 raft markers distributed and re-distributed at mounds but not depressions of T-cell membrane fluctuations. Such mound-top distribution of lipid raft markers or lipid rafts provides spatial advantage for lipid rafts or contact molecules interacting readily with neighboring cells or free molecules.

  20. Ultra low frequency (ULF) electromagnetic anomalies associated with large earthquakes in Java Island, Indonesia by using wavelet transform and detrended fluctuation analysis

    NASA Astrophysics Data System (ADS)

    Febriani, F.; Han, P.; Yoshino, C.; Hattori, K.; Nurdiyanto, B.; Effendi, N.; Maulana, I.; Gaffar, E.

    2014-04-01

    Indonesia is one of the most seismically active regions in the world and mitigation of seismic hazard is important. It is reported that Ultra low frequency (ULF) geomagnetic anomalies are one of the most convincing phenomena preceding large earthquakes (EQs). In this paper we have analyzed geomagnetic data at Pelabuhan Ratu (PLR) (7.01° S, 106.56° E), Sukabumi, West Java, Indonesia, from 1 September 2008 to 31 October 2010. There are twelve moderate-large EQs (M ≥ 5) within 160 km from the station during the analyzed period. The largest one is the M =7.5 EQ (depth = 57 km, epicentral distance = 135 km, 2 September 2009) based on EQ catalog of Indonesian Meteorological, Climatological and Geophysical Agency (BMKG). To investigate the ULF geomagnetic anomalous variations preceding all the EQs, spectral density ratio at the frequency range of 0.01 ± 0.003 Hz based on wavelet transform (WT) and detrended fluctuation analysis (DFA) have been carried out. The spectral density ratio results show the enhancements a few weeks before the largest EQ. The enhancement persists about one week and reaches a maximum on 16 August 2009. At the same time, the result of the DFA presents the decrease of α value. For other EQs, there are no clear increases of the spectral density ratio with simultaneous decrease of α value. When these phenomena occur, the value of Dst index shows that there are no peculiar global geomagnetic activities at the low latitude region. The above results are suggestive of the relation between the detected anomalies and the largest EQ.

  1. Fluctuations in Brain Temperature Induced by Lypopolysaccharides: Central and Peripheral Contributions

    PubMed Central

    Tang, Jeremy S.; Kiyatkin, Eugene A.

    2010-01-01

    In this study, we examined changes in central (anterior-preoptic hypothalamus) and peripheral (temporal muscle and facial skin) temperatures in freely moving rats following intravenous administration of bacterial lipopolysaccharides (LPS) at low doses (1 and 10 μg/kg) at thermoneutral conditions (28°C). Recordings were made with high temporal resolution (5-s bin) and the effects of LPS were compared with those induced by a tail-pinch, a standard arousing somato-sensory stimulus. At each dose, LPS moderately elevated brain, muscle and skin temperatures. In contrast to rapid, monophasic and relatively short hyperthermic responses induced by a tail-pinch, LPS-induced increases in brain and muscle temperatures occurred with ~40 min onset latencies, showed three not clearly defined phases, were slightly larger with the 10 μm/kg dose and maintained for the entire 4-hour post-injection recording duration. Based on dynamics of brain-muscle and skin-muscle temperature differentials, it appears that the hyperthermic response induced by LPS at the lowest dose originates from enhanced peripheral heat production, with no evidence of brain metabolic activation and skin vasoconstriction. While peripheral heat production also appears to determine the first phase of brain and body temperature elevation with LPS at 10 μg/kg, a further prolonged increase in brain-muscle differentials (onset at ~100 min) suggests metabolic brain activation as a factor contributing to brain and body hyperthermia. At this dose, skin temperature increase was weaker than in temporal muscle, suggesting vasoconstriction as another contributor to brain/ body hyperthermia. Therefore, although both LPS at low doses and salient sensory stimuli moderately increase brain and body temperatures, these hyperthermic responses have important qualitative differences, reflecting unique underlying mechanisms. PMID:21150339

  2. Wave-induced mass transport affects daily Escherichia coli fluctuations in nearshore water

    USGS Publications Warehouse

    Ge, Zhongfu; Whitman, Richard L.; Nevers, Meredith B.; Phanikumar, Mantha S.

    2012-01-01

    Characterization of diel variability of fecal indicator bacteria concentration in nearshore waters is of particular importance for development of water sampling standards and protection of public health. Significant nighttime increase in Escherichia coli (E. coli) concentration in beach water, previously observed at marine sites, has also been identified in summer 2000 from fixed locations in waist- and knee-deep waters at Chicago 63rd Street Beach, an embayed, tideless, freshwater beach with low currents at night (approximately 0.015 m s–1). A theoretical model using wave-induced mass transport velocity for advection was developed to assess the contribution of surface waves to the observed nighttime E. coli replenishment in the nearshore water. Using average wave conditions for the summer season of year 2000, the model predicted an amount of E. coli transported from water of intermediate depth, where sediment resuspension occurred intermittently, that would be sufficient to have elevated E. coli concentration in the surf and swash zones as observed. The nighttime replenishment of E. coli in the surf and swash zones revealed here is an important phase in the cycle of diel variations of E. coli concentration in nearshore water. According to previous findings in Ge et al. (Environ. Sci. Technol. 2010, 44, 6731–6737), enhanced current circulation in the embayment during the day tends to displace and deposit material offshore, which partially sets up the system by the early evening for a new period of nighttime onshore movement. This wave-induced mass transport effect, although facilitating a significant base supply of material shoreward, can be perturbed or significantly influenced by high currents (orders of magnitude larger than a typical wave-induced mass transport velocity), current-induced turbulence, and tidal forcing.

  3. Influence of Plasma Pressure Fluctuation on RF Wave Propagation

    NASA Astrophysics Data System (ADS)

    Liu, Zhiwei; Bao, Weimin; Li, Xiaoping; Liu, Donglin; Zhou, Hui

    2016-02-01

    Pressure fluctuations in the plasma sheath from spacecraft reentry affect radio-frequency (RF) wave propagation. The influence of these fluctuations on wave propagation and wave properties is studied using methods derived by synthesizing the compressible turbulent flow theory, plasma theory, and electromagnetic wave theory. We study these influences on wave propagation at GPS and Ka frequencies during typical reentry by adopting stratified modeling. We analyzed the variations in reflection and transmission properties induced by pressure fluctuations. Our results show that, at the GPS frequency, if the waves are not totally reflected then the pressure fluctuations can remarkably affect reflection, transmission, and absorption properties. In extreme situations, the fluctuations can even cause blackout. At the Ka frequency, the influences are obvious when the waves are not totally transmitted. The influences are more pronounced at the GPS frequency than at the Ka frequency. This suggests that the latter can mitigate blackout by reducing both the reflection and the absorption of waves, as well as the influences of plasma fluctuations on wave propagation. Given that communication links with the reentry vehicles are susceptible to plasma pressure fluctuations, the influences on link budgets should be taken into consideration. supported by the National Basic Research Program of China (No. 2014CB340205) and National Natural Science Foundation of China (No. 61301173)

  4. Surface-induced weak orientational order and role of isotropic-nematic interface fluctuations in the appearance of an induced nematic film.

    PubMed

    Pikina, E; Rosenblatt, C

    2012-09-01

    Recently the nontrivial spatial and temperature dependence of the surface-induced weak planar orientational order parameter Q(z, T) was determined just above the isotropic-nematic (IN) phase transition point (Ji-H. Lee et al., Phys. Rev. Lett. 102, 167801 (2009)). In this paper we present a theoretical explanation of the observed behaviour. We obtain expressions for the short-range and long-range contributions to the interface potential of the induced nematic film and specify the repulsive character of the interaction between the soft IN interface and the external bounding substrate. It is shown that the small value of the IN interfacial tension results in the renormalization of the repulsive interaction potential due to the thermal fluctuations of the soft IN interface. This leads to an increase of the equilibrium thickness of the induced nematic film and the appearance of a step-like orientational order parameter profile. We find that only renormalized short-range and thermal pseudo-Casimir interactions are essential for the appearance of the induced nematic film, which provide the observed thickness, h ~ 30 nm, of this film. The long-range van der Waals interaction is shown to be negligibly small and the dominant role is played by the renormalized short-range repulsion. Fitting of the experimental order parameter profiles (Ji-H. Lee et al. (2009)) with the expressions based on these interactions makes it possible to determine the material parameters of the system, including the amplitudes of the surface interaction, the IN interfacial tension and the interfacial coherence length. The agreement between theory and experiment confirms the importance of the interface fluctuation renormalization of the interface potentials for soft interfaces.

  5. Fluctuating pulse propagation in resonant nonlinear media: self-induced transparency random phase soliton formation.

    PubMed

    Mokhtarpour, Laleh; Ponomarenko, Sergey A

    2015-11-16

    We numerically investigate partially coherent short pulse propagation in nonlinear media near optical resonance. We examine how the pulse state of coherence at the source affects the evolution of the ensemble averaged intensity, mutual coherence function, and temporal degree of coherence of the pulse ensemble. We report evidence of self-induced transparency random phase soliton formation for the relatively coherent incident pulses with sufficiently large average areas. We also show that random pulses lose their coherence on propagation in resonant media and we explain this phenomenon in qualitative terms.

  6. Two-dimensional electromagnetically induced grating via gain and phase modulation in a two-level system

    NASA Astrophysics Data System (ADS)

    Cheng, Guang-Ling; Cong, Lu; Chen, Ai-Xi

    2016-04-01

    A scheme for two-dimensional (2D) electromagnetically induced grating via spatial gain and phase modulation is presented in a two-level atomic system. Based on the interactions of two orthogonal standing-wave fields, the atom could diffract the weak probe beam into high-order directions and a 2D diffraction grating is generated. It is shown that the diffraction efficiency of the grating can be efficiently manipulated by controlling the Rabi frequencies of control fields, the detunings of the control and probe fields, and interaction length. Different from 2D cross-grating via electromagnetically induced transparency in a four-level atomic system, the present scheme results from the spatial modulation of gain and phase in a simple two-level system, which could lead to 2D gain-phase grating with larger diffraction intensities in the diffraction directions. The studies we present may have potential applications in developing photon devices for optical-switching, optical imaging and quantum information processing.

  7. Stimulated electromagnetic terahertz emissions (SEE) from laser-induced plasma filaments

    NASA Astrophysics Data System (ADS)

    Isham, Brett; Kunhardt, Erich

    2016-07-01

    Advances in terawatt laser technology have made it possible to ionize the troposphere in long (centimeters to kilometers), narrow (less than 1 mm), wire-like plasma filaments. These filaments emit high-power stimulated electromagnetic emissions (SEE) at terahertz (submillimeter) frequencies, a frontier in the electromagnetic spectrum lying between the microwave and far infrared bands. Using an accepted model for the plasma oscillations in the filament and a thin-wire approximation, we have calculated the current density and the resulting pattern of terahertz radiation emitted by the filament. The conical shape and opening angle of the calculated radiation pattern match those of recent measurements. Future work could include measurements of both the radiation pattern and of the frequency spectrum, for comparison with detailed calculations of filament plasma processes. Potential applications include high-resolution imaging and remote spectroscopic identification of chemical substances.

  8. Evolution of laser induced electromagnetic postsolitons in multi-species plasma

    SciTech Connect

    Liu, Yue Gu, Yanjun; Weber, Stefan; Korn, Georg; Klimo, Ondřej; Esirkepov, Timur Zh.; Bulanov, Sergei V.

    2015-11-15

    The evolution of an s-polarized relativistic electromagnetic soliton created in multi-species plasma by an intense short laser pulse is investigated using two-dimensional particle-in-cell simulations. The multi-component plasma consists of electrons and high-Z ions with a small addition of protons. By comparison, the evolution of postsoliton is very different from that in hydrogen plasma. A halo-like structure is found in spatial patterns of both electromagnetic fields and electron densities. The process of energy depletion is much slower due to the smaller charge-to-mass ratio of ions, which implies a better way of detecting postsolitons in simulations and experiments. In addition, it is found that the Coulomb explosion of high-Z ions in the postsoliton stage facilitates low-Z ion acceleration, and the maximum energy of low-Z ions increases with the component ratio of high-Z to low-Z ions.

  9. Beat-induced fluctuations in auditory cortical beta-band activity: using EEG to measure age-related changes

    PubMed Central

    Cirelli, Laura K.; Bosnyak, Dan; Manning, Fiona C.; Spinelli, Christina; Marie, Céline; Fujioka, Takako; Ghahremani, Ayda; Trainor, Laurel J.

    2014-01-01

    People readily extract regularity in rhythmic auditory patterns, enabling prediction of the onset of the next beat. Recent magnetoencephalography (MEG) research suggests that such prediction is reflected by the entrainment of oscillatory networks in the brain to the tempo of the sequence. In particular, induced beta-band oscillatory activity from auditory cortex decreases after each beat onset and rebounds prior to the onset of the next beat across tempi in a predictive manner. The objective of the present study was to examine the development of such oscillatory activity by comparing electroencephalography (EEG) measures of beta-band fluctuations in 7-year-old children to adults. EEG was recorded while participants listened passively to isochronous tone sequences at three tempi (390, 585, and 780 ms for onset-to-onset interval). In adults, induced power in the high beta-band (20–25 Hz) decreased after each tone onset and rebounded prior to the onset of the next tone across tempo conditions, consistent with MEG findings. In children, a similar pattern was measured in the two slower tempo conditions, but was weaker in the fastest condition. The results indicate that the beta-band timing network works similarly in children, although there are age-related changes in consistency and the tempo range over which it operates. PMID:25071691

  10. The 4-Dimensional Plant: Effects of Wind-Induced Canopy Movement on Light Fluctuations and Photosynthesis

    PubMed Central

    Burgess, Alexandra J.; Retkute, Renata; Preston, Simon P.; Jensen, Oliver E.; Pound, Michael P.; Pridmore, Tony P.; Murchie, Erik H.

    2016-01-01

    Physical perturbation of a plant canopy brought about by wind is a ubiquitous phenomenon and yet its biological importance has often been overlooked. This is partly due to the complexity of the issue at hand: wind-induced movement (or mechanical excitation) is a stochastic process which is difficult to measure and quantify; plant motion is dependent upon canopy architectural features which, until recently, were difficult to accurately represent and model in 3-dimensions; light patterning throughout a canopy is difficult to compute at high-resolutions, especially when confounded by other environmental variables. Recent studies have reinforced the expectation that canopy architecture is a strong determinant of productivity and yield; however, links between the architectural properties of the plant and its mechanical properties, particularly its response to wind, are relatively unknown. As a result, biologically relevant data relating canopy architecture, light- dynamics, and short-scale photosynthetic responses in the canopy setting are scarce. Here, we hypothesize that wind-induced movement will have large consequences for the photosynthetic productivity of our crops due to its influence on light patterning. To address this issue, in this study we combined high resolution 3D reconstructions of a plant canopy with a simple representation of canopy perturbation as a result of wind using solid body rotation in order to explore the potential effects on light patterning, interception, and photosynthetic productivity. We looked at two different scenarios: firstly a constant distortion where a rice canopy was subject to a permanent distortion throughout the whole day; and secondly, a dynamic distortion, where the canopy was distorted in incremental steps between two extremes at set time points in the day. We find that mechanical canopy excitation substantially alters light dynamics; light distribution and modeled canopy carbon gain. We then discuss methods required for

  11. Experimental study on unsteady cloud cavity behaviour and induced pressure fluctuation in a convergent-divergent channel using simultaneous measurement technique

    NASA Astrophysics Data System (ADS)

    Chen, G. H.; Y Wang, G.; Huang, B.; Huang, X.; Gao, Y.

    2013-12-01

    To address the unsteady cavity behaviour and induced pressure fluctuation in cloud cavitating flow, cavitation images and pressure fluctuation signals are simultaneously acquired by high speed visualization system and 4 piezo-electric transducers in a convergent-divergent channel. The cavitation images are processed by using a home-developed software to obtain the time evolutions of global cavity area. Frequency analysis is conducted for both global cavity area and pressure signal. Bubble dynamics is introduced to analyze the correlation between pressure fluctuation in the downstream and global cavity behaviour. Two conclusions are achieved: First, in cloud cavitating flow, the time evolution of both the cavity behaviour and pressure fluctuation are quasi-periodic, one quasi-period can be divided into three main stages: growth of attached cavity, shedding of attached cavity, coalescence and collapse of detached cavity. Second, the dominant frequency of global cavity area and pressure fluctuation on 4 transducers are the same, it's 20Hz in this study. Third, it's found that during the stage of growth of attached cavity and growth, collapse of detached cavity, the correlation between global cavity area and induced pressure in the downstream is similar with that of a single bubble; while, such correlation is not clear when several travelling cavities exist at the same time.

  12. Fluctuations of electrical and mechanical properties of diamond induced by interstitial hydrogen

    NASA Astrophysics Data System (ADS)

    Zhuang, Chun-Qiang; Liu, Lei

    2015-01-01

    While experimental evidence demonstrates that the presence of hydrogen (H) impurities in diamond films plays a significant role in determining their physical properties, the small radius of the H atom makes detecting such impurities quite a challenging task. In the present work, first-principles calculations were employed to provide an insight into the effects of the interstitial hydrogen on the electrical and mechanical properties of diamond crystals at the atomic level. The migrated pathways of the interstitial hydrogen are dictated by energetic considerations. Some new electronic states are formed near the Fermi level. The interstitial hydrogen markedly narrows the bandgap of the diamond and weakens the diamond crystal. The obvious decrement of the critical strain clearly implies the presence of an H-induced embrittlement effect. Project supported by the Project of Construction of Innovative Teams and Teacher Career Development for Universities and Colleges under Beijing Municipality, China (Grant No. IDHT20140504), the National Natural Science Foundation of China (Grant No. 51402009), and the Foundation for Young Scholars of Beijing University of Technology, China.

  13. Induced Polarization with Electromagnetic Coupling: 3D Spectral Imaging Theory EMSP Project No. 73836

    SciTech Connect

    Morgan, F. Dale

    2003-06-01

    This report summarizes the research work completed on the project between December 2001 and September 2002. (1) A model of all Spectral IP capacitive couplings revealed that potential bearing electrodes should be carefully chosen to obviate some of the capacitive coupling problems. This need becomes more important for borehole sampling. Thus, work had been done to design a porous pot electrode hat has all the desired characteristics (low input impedance = 100{Omega}, low noise = 1 {micro}V/{radical} z, low temperature sensitivity = 10{micro}V/{sup o}C) and that can be implanted in a borehole for up to two ears. Further constructional/fabrication details will be given in the final report. The attached pictures are rom a sample of the prototype electrode. Four strings, each consisting of 14 electrodes (7 potential electrodes alternated with 7 metallic-copper current electrodes, each electrode 6ft apart), were constructed and are to be employed into the four boreholes. (They were eventually deployed in Dec. 2002 and measurements acquired in March 2003). (2) The MIT's Earth Resources Laboratory (ERL) performed Spectral Induced Polarization SIP and Time Domain Induced Polarization (TDIP) measurements at the A-14 Outfall during the summer of Y01 as a participant in a DOE-sponsored exercise to assess the state-of-the-art in cross-borehole IP technology for delineating subsurface contaminants. To demonstrate the utility of SIP to map DNAPL contaminants, we inverted cross-borehole SIP data, taken within a very narrow frequency bandwidth of 1/32 o 9/32 Hz. The narrow bandwidth was selected after carefully studying when effects of emc, electrode polarization, etc. begin to set in. The upper frequency is limited by electromagnetic couplings (emc) and strong capacitive behavior observed for the electrodes and the low-frequency limit is set by the time to take measurements. Because below 9/32 Hz, the IP response seems to be greater than emc in all our measurements, the data was

  14. Zero field splitting fluctuations induced phase relaxation of Gd3+ in frozen solutions at cryogenic temperatures

    NASA Astrophysics Data System (ADS)

    Raitsimring, A.; Dalaloyan, A.; Collauto, A.; Feintuch, A.; Meade, T.; Goldfarb, D.

    2014-11-01

    Distance measurements using double electron-electron resonance (DEER) and Gd3+ chelates for spin labels (GdSL) have been shown to be an attractive alternative to nitroxide spin labels at W-band (95 GHz). The maximal distance that can be accessed by DEER measurements and the sensitivity of such measurements strongly depends on the phase relaxation of Gd3+ chelates in frozen, glassy solutions. In this work, we explore the phase relaxation of Gd3+-DOTA as a representative of GdSL in temperature and concentration ranges typically used for W-band DEER measurements. We observed that in addition to the usual mechanisms of phase relaxation known for nitroxide based spin labels, GdSL are subjected to an additional phase relaxation mechanism that features an increase in the relaxation rate from the center to the periphery of the EPR spectrum. Since the EPR spectrum of GdSL is the sum of subspectra of the individual EPR transitions, we attribute this field dependence to transition dependent phase relaxation. Using simulations of the EPR spectra and its decomposition into the individual transition subspectra, we isolated the phase relaxation of each transition and found that its rate increases with |ms|. We suggest that this mechanism is due to transient zero field splitting (tZFS), where its magnitude and correlation time are scaled down and distributed as compared with similar situations in liquids. This tZFS induced phase relaxation mechanism becomes dominant (or at least significant) when all other well-known phase relaxation mechanisms, such as spectral diffusion caused by nuclear spin diffusion, instantaneous and electron spin spectral diffusion, are significantly suppressed by matrix deuteration and low concentration, and when the temperature is sufficiently low to disable spin lattice interaction as a source of phase relaxation.

  15. Zero field splitting fluctuations induced phase relaxation of Gd3+ in frozen solutions at cryogenic temperatures.

    PubMed

    Raitsimring, A; Dalaloyan, A; Collauto, A; Feintuch, A; Meade, T; Goldfarb, D

    2014-11-01

    Distance measurements using double electron-electron resonance (DEER) and Gd(3+) chelates for spin labels (GdSL) have been shown to be an attractive alternative to nitroxide spin labels at W-band (95GHz). The maximal distance that can be accessed by DEER measurements and the sensitivity of such measurements strongly depends on the phase relaxation of Gd(3+) chelates in frozen, glassy solutions. In this work, we explore the phase relaxation of Gd(3+)-DOTA as a representative of GdSL in temperature and concentration ranges typically used for W-band DEER measurements. We observed that in addition to the usual mechanisms of phase relaxation known for nitroxide based spin labels, GdSL are subjected to an additional phase relaxation mechanism that features an increase in the relaxation rate from the center to the periphery of the EPR spectrum. Since the EPR spectrum of GdSL is the sum of subspectra of the individual EPR transitions, we attribute this field dependence to transition dependent phase relaxation. Using simulations of the EPR spectra and its decomposition into the individual transition subspectra, we isolated the phase relaxation of each transition and found that its rate increases with |ms|. We suggest that this mechanism is due to transient zero field splitting (tZFS), where its magnitude and correlation time are scaled down and distributed as compared with similar situations in liquids. This tZFS induced phase relaxation mechanism becomes dominant (or at least significant) when all other well-known phase relaxation mechanisms, such as spectral diffusion caused by nuclear spin diffusion, instantaneous and electron spin spectral diffusion, are significantly suppressed by matrix deuteration and low concentration, and when the temperature is sufficiently low to disable spin lattice interaction as a source of phase relaxation. PMID:25442776

  16. Modeling and Simulation of Upset-Inducing Disturbances for Digital Systems in an Electromagnetic Reverberation Chamber

    NASA Technical Reports Server (NTRS)

    Torres-Pomales, Wilfredo

    2014-01-01

    This report describes a modeling and simulation approach for disturbance patterns representative of the environment experienced by a digital system in an electromagnetic reverberation chamber. The disturbance is modeled by a multi-variate statistical distribution based on empirical observations. Extended versions of the Rejection Samping and Inverse Transform Sampling techniques are developed to generate multi-variate random samples of the disturbance. The results show that Inverse Transform Sampling returns samples with higher fidelity relative to the empirical distribution. This work is part of an ongoing effort to develop a resilience assessment methodology for complex safety-critical distributed systems.

  17. Effect of disorder on temporal fluctuations in drying-induced cracking.

    PubMed

    Villalobos, Gabriel; Kun, Ferenc; Muñoz, José D

    2011-10-01

    We investigate by means of computer simulations the effect of structural disorder on the statistics of cracking for a thin layer of material under uniform and isotropic drying. For this purpose, the layer is discretized into a triangular lattice of springs with a slightly randomized arrangement. The drying process is captured by reducing the natural length of all springs by the same factor, and the amount of quenched disorder is controlled by varying the width ξ of the distribution of the random breaking thresholds for the springs. Once a spring breaks, the redistribution of the load may trigger an avalanche of breaks, not necessarily as part of the same crack. Our computer simulations revealed that the system exhibits a phase transition with the amount of disorder as control parameter: at low disorders, the breaking process is dominated by a macroscopic crack at the beginning, and the size distribution of the subsequent breaking avalanches shows an exponential form. At high disorders, the fracturing proceeds in small-sized avalanches with an exponential distribution, generating a large number of microcracks, which eventually merge and break the layer. Between both phases, a sharp transition occurs at a critical amount of disorder ξ(c)=0.40±0.01, where the avalanche size distribution becomes a power law with exponent τ=2.6±0.08, in agreement with the mean-field value τ=5/2 of the fiber bundle model. Moreover, good quality data collapses from the finite-size scaling analysis show that the average value of the largest burst ⟨Δ(max)⟩ can be identified as the order parameter, with β/ν=1.4 and 1/ν≃1.0, and that the average ratio ⟨m(2)/m(1)⟩ of the second m(2) and first moments m(1) of the avalanche size distribution shows similar behavior to the susceptibility of a continuous transition, with γ/ν=1, 1/ν≃0.9. These results suggest that the disorder-induced transition of the breakup of thin layers is analogous to a continuous phase transition

  18. Effect of disorder on temporal fluctuations in drying-induced cracking.

    PubMed

    Villalobos, Gabriel; Kun, Ferenc; Muñoz, José D

    2011-10-01

    We investigate by means of computer simulations the effect of structural disorder on the statistics of cracking for a thin layer of material under uniform and isotropic drying. For this purpose, the layer is discretized into a triangular lattice of springs with a slightly randomized arrangement. The drying process is captured by reducing the natural length of all springs by the same factor, and the amount of quenched disorder is controlled by varying the width ξ of the distribution of the random breaking thresholds for the springs. Once a spring breaks, the redistribution of the load may trigger an avalanche of breaks, not necessarily as part of the same crack. Our computer simulations revealed that the system exhibits a phase transition with the amount of disorder as control parameter: at low disorders, the breaking process is dominated by a macroscopic crack at the beginning, and the size distribution of the subsequent breaking avalanches shows an exponential form. At high disorders, the fracturing proceeds in small-sized avalanches with an exponential distribution, generating a large number of microcracks, which eventually merge and break the layer. Between both phases, a sharp transition occurs at a critical amount of disorder ξ(c)=0.40±0.01, where the avalanche size distribution becomes a power law with exponent τ=2.6±0.08, in agreement with the mean-field value τ=5/2 of the fiber bundle model. Moreover, good quality data collapses from the finite-size scaling analysis show that the average value of the largest burst ⟨Δ(max)⟩ can be identified as the order parameter, with β/ν=1.4 and 1/ν≃1.0, and that the average ratio ⟨m(2)/m(1)⟩ of the second m(2) and first moments m(1) of the avalanche size distribution shows similar behavior to the susceptibility of a continuous transition, with γ/ν=1, 1/ν≃0.9. These results suggest that the disorder-induced transition of the breakup of thin layers is analogous to a continuous phase transition.

  19. Zero-resistance states induced by electromagnetic-wave excitation in GaAs/AlGaAs heterostructures.

    PubMed

    Mani, Ramesh G; Smet, Jürgen H; von Klitzing, Klaus; Narayanamurti, Venkatesh; Johnson, William B; Umansky, Vladimir

    2002-12-12

    The observation of vanishing electrical resistance in condensed matter has led to the discovery of new phenomena such as, for example, superconductivity, where a zero-resistance state can be detected in a metal below a transition temperature T(c) (ref. 1). More recently, quantum Hall effects were discovered from investigations of zero-resistance states at low temperatures and high magnetic fields in two-dimensional electron systems (2DESs). In quantum Hall systems and superconductors, zero-resistance states often coincide with the appearance of a gap in the energy spectrum. Here we report the observation of zero-resistance states and energy gaps in a surprising setting: ultrahigh-mobility GaAs/AlGaAs heterostructures that contain a 2DES exhibit vanishing diagonal resistance without Hall resistance quantization at low temperatures and low magnetic fields when the specimen is subjected to electromagnetic wave excitation. Zero-resistance-states occur about magnetic fields B = 4/5 Bf and B = 4/9 Bf, where Bf = 2pifm*/e,m* is the electron mass, e is the electron charge, and f is the electromagnetic-wave frequency. Activated transport measurements on the resistance minima also indicate an energy gap at the Fermi level. The results suggest an unexpected radiation-induced, electronic-state-transition in the GaAs/AlGaAs 2DES.

  20. Functional brain measurements within the prefrontal area on pseudo-"blindsight" induced by extremely low frequency electromagnetic stimulations

    NASA Astrophysics Data System (ADS)

    Nakagawa, Hidenori; Ueno, Shoogo

    2015-05-01

    For evaluating the effects of phosphene as pseudo-blindsight closely, we used functional near-infrared spectroscopy to investigate whether or not the phosphene appearance itself substantially affects the hemodynamic responses of the prefrontal area. Seven healthy volunteers ranging in age from 22 to 72 participated in the visual stimulation experiments. First, we examined the influences of electromagnetic stimulations at around the threshold (10 mT) for a blindsight-like phosphene on the responses. According to the results of the aged volunteers, we found the possibility that the delay in the phosphene perception might be caused by aging beyond a certain age. In the results of our measurements using the stimulation of 50 mT, no significant difference in the perception delay for all the volunteers could be detected. When the field strength was decreased from 50 mT to the threshold in steps of 10 mT, the results obtained at the threshold are equivalent to that obtained at 50 mT. Our data strongly support the hypothesis that pseudo-blindsight induced by electromagnetic stimulation of above 50 mT is able to excite all the volunteers' retinal photoreceptor cells provisionally. Hence the continuous stimulations for a long period of time might gradually activate synaptic plasticity on the neural network of the retina.

  1. Fluctuations between multiple EF-G-induced chimeric tRNA states during translocation on the ribosome

    NASA Astrophysics Data System (ADS)

    Adio, Sarah; Senyushkina, Tamara; Peske, Frank; Fischer, Niels; Wintermeyer, Wolfgang; Rodnina, Marina V.

    2015-06-01

    The coupled translocation of transfer RNA and messenger RNA through the ribosome entails large-scale structural rearrangements, including step-wise movements of the tRNAs. Recent structural work has visualized intermediates of translocation induced by elongation factor G (EF-G) with tRNAs trapped in chimeric states with respect to 30S and 50S ribosomal subunits. The functional role of the chimeric states is not known. Here we follow the formation of translocation intermediates by single-molecule fluorescence resonance energy transfer. Using EF-G mutants, a non-hydrolysable GTP analogue, and fusidic acid, we interfere with either translocation or EF-G release from the ribosome and identify several rapidly interconverting chimeric tRNA states on the reaction pathway. EF-G engagement prevents backward transitions early in translocation and increases the fraction of ribosomes that rapidly fluctuate between hybrid, chimeric and posttranslocation states. Thus, the engagement of EF-G alters the energetics of translocation towards a flat energy landscape, thereby promoting forward tRNA movement.

  2. Neuroprotective effects of lotus seedpod procyanidins on extremely low frequency electromagnetic field-induced neurotoxicity in primary cultured hippocampal neurons.

    PubMed

    Yin, Chunchun; Luo, Xiaoping; Duan, Yuqing; Duan, Wenyi; Zhang, Haihui; He, Yuanqing; Sun, Guibo; Sun, Xiaobo

    2016-08-01

    The present study investigated the protective effects of lotus seedpod procyanidins (LSPCs) on extremely low frequency electromagnetic field (ELF-EMF)-induced neurotoxicity in primary cultured rat hippocampal neurons and the underlying molecular mechanism. The results of MTT, morphological observation, superoxide dismutase (SOD) and malondialdehyde (MDA) assays showed that compared with control, incubating neurons under ELF-EMF exposure significantly decreased cell viability and increased the number of apoptotic cells, whereas LSPCs evidently protected the hippocampal neurons against ELF-EMF-induced cell damage. Moreover, a certain concentration of LSPCs inhibited the elevation of intracellular reactive oxygen species (ROS) and Ca(2+) level, as well as prevented the disruption of mitochondrial membrane potential induced by ELF-EMF exposure. In addition, supplementation with LSPCs could alleviate DNA damage, block cell cycle arrest at S phase, and inhibit apoptosis and necrosis of hippocampal neurons under ELF-EMF exposure. Further study demonstrated that LSPCs up-regulated the activations of Bcl-2, Bcl-xl proteins and suppressed the expressions of Bad, Bax proteins caused by ELF-EMF exposure. In conclusion, these findings revealed that LSPCs protected against ELF-EMF-induced neurotoxicity through inhibiting oxidative stress and mitochondrial apoptotic pathway. PMID:27470406

  3. A new theoretical model for transmembrane potential and ion currents induced in a spherical cell under low frequency electromagnetic field.

    PubMed

    Zheng, Yu; Gao, Yang; Chen, Ruijuan; Wang, Huiquan; Dong, Lei; Dou, Junrong

    2016-10-01

    Time-varying electromagnetic fields (EMF) can induce some physiological effects in neuronal tissues, which have been explored in many applications such as transcranial magnetic stimulation. Although transmembrane potentials and induced currents have already been the subjects of many theoretical studies, most previous works about this topic are mainly completed by utilizing Maxwell's equations, often by solving a Laplace equation. In previous studies, cells were often considered to be three-compartment models with different electroconductivities in different regions (three compartments are often intracellular regions, membrane, and extracellular regions). However, models like that did not take dynamic ion channels into consideration. Therefore, one cannot obtain concrete ionic current changes such as potassium current change or sodium current change by these models. The aim of the present work is to present a new and more detailed model for calculating transmembrane potentials and ionic currents induced by time-varying EMF. Equations used in the present paper originate from Nernst-Plank equations, which are ionic current-related equations. The main work is to calculate ionic current changes induced by EMF exposure, and then transmembrane potential changes are calculated with Hodgkin-Huxley model. Bioelectromagnetics. 37:481-492, 2016. © 2016 Wiley Periodicals, Inc. PMID:27438778

  4. Intrinsic spontaneous emission-induced fluctuations of the output optical beam power and phase in a diode amplifier

    NASA Astrophysics Data System (ADS)

    Bogatov, A. P.; Drakin, A. E.; D'yachkov, N. V.; Gushchik, T. I.

    2016-08-01

    Output optical beam intensity and phase fluctuations are analysed in a classical approach to describing the propagation and amplification of spontaneous emission in the active region of a laser diode with a gain saturated by input monochromatic light. We find their spectral densities and dispersion and the correlation coefficient of the two-dimensional probability distribution function of the fluctuations.

  5. Sub-wavelength imaging and field mapping via electromagnetically induced transparency and Autler-Townes splitting in Rydberg atoms

    SciTech Connect

    Holloway, Christopher L. Gordon, Joshua A.; Schwarzkopf, Andrew; Anderson, David A.; Miller, Stephanie A.; Thaicharoen, Nithiwadee; Raithel, Georg

    2014-06-16

    We present a technique for measuring radio-frequency (RF) electric field strengths with sub-wavelength resolution. We use Rydberg states of rubidium atoms to probe the RF field. The RF field causes an energy splitting of the Rydberg states via the Autler-Townes effect, and we detect the splitting via electromagnetically induced transparency (EIT). We use this technique to measure the electric field distribution inside a glass cylinder with applied RF fields at 17.04 GHz and 104.77 GHz. We achieve a spatial resolution of ≈100 μm, limited by the widths of the laser beams utilized for the EIT spectroscopy. We numerically simulate the fields in the glass cylinder and find good agreement with the measured fields. Our results suggest that this technique could be applied to image fields on a small spatial scale over a large range of frequencies, up into the sub-terahertz regime.

  6. Controlling multi-wave mixing signals via photonic band gap of electromagnetically induced absorption grating in atomic media.

    PubMed

    Zhang, Yiqi; Wu, Zhenkun; Yao, Xin; Zhang, Zhaoyang; Chen, Haixia; Zhang, Huaibin; Zhang, Yanpeng

    2013-12-01

    We experimentally demonstrate dressed multi-wave mixing (MWM) and the reflection of the probe beam due to electromagnetically induced absorption (EIA) grating can coexist in a five-level atomic ensemble. The reflection is derived from the photonic band gap (PBG) of EIA grating, which is much broader than the PBG of EIT grating. Therefore, EIA-type PBG can reflect more energy from probe than EIT-type PBG does, which can effectively affect the MWM signal. The EIA-type as well as EIT-type PBG can be controlled by multiple parameters including the frequency detunings, propagation angles and powers of the involved light fields. Also, the EIA-type PBG by considering both the linear and third-order nonlinear refractive indices is also investigated. The theoretical analysis agrees well with the experimental results. This investigation has potential applications in all-optical communication and information processing.

  7. Weak-light rogue waves, breathers, and their active control in a cold atomic gas via electromagnetically induced transparency

    NASA Astrophysics Data System (ADS)

    Liu, Junyang; Hang, Chao; Huang, Guoxiang

    2016-06-01

    We propose a scheme to demonstrate the existence of optical Peregrine rogue waves and Akhmediev and Kuznetsov-Ma breathers and realize their active control via electromagnetically induced transparency (EIT). The system we suggest is a cold, Λ -type three-level atomic gas interacting with a probe and a control laser fields and working under EIT condition. We show that, based on EIT with an incoherent optical pumping, which can be used to cancel optical absorption, (1+1)-dimensional optical Peregrine rogue waves, Akhmediev breathers, and Kuznetsov-Ma breathers can be generated with very low light power. In addition, we demonstrate that the Akhmediev and Kuznetsov-Ma breathers in (2+1)-dimensions obtained can be actively manipulated by using an external magnetic field. As a result, these breathers can display trajectory deflections and bypass obstacles during propagation.

  8. Zero to π Continuously Controllable Cross Phase Modulation in Doppler Broadened N-Type Electromagnetically Induced Transparency Medium

    PubMed Central

    Li, R. B.; Zhu, C. J.; Deng, L.; Hagley, E. W.

    2016-01-01

    We demonstrate an observation of zero to π continuously controllable cross-phase-modulation based on N-type electromagnetically induced transparency scheme in a room-temperature 87Rb vapor. We theoretically and experimentally show that the signal field acquires a π phase shift compared with the reference light in the presence of the phase-control field. Using the method of the optical Mach-Zehnder interferometer, we demonstrate that a zero to π continuously controllable phase gate can be built by modulating the phase-control field. In addition, our theoretical calculation agrees well with the experimental observation, and the results presented in this work hold the potential applications for the orthogonal polarization/vector gate in the quantum information processing. PMID:27453675

  9. Effect of hydrostatic pressure and magnetic field on electromagnetically induced transparency based nonlinear frequency conversion in quantum ring

    NASA Astrophysics Data System (ADS)

    Gumber, Sukirti; Gambhir, Monica; Jha, Pradip Kumar; Mohan, Man

    2016-10-01

    We study the combined effect of hydrostatic pressure and magnetic field on electromagnetically induced transparency in quantum ring. The high flexibility in size and shape of ring makes it possible to fabricate a nearly perfect two-dimensional quantum structure. We also explore the dependence of frequency conversion, measured in terms of third order nonlinear susceptibility χ(3) , on coupling field, hydrostatic pressure and magnetic field. Although, a dip in χ(3) is observed with the introduction of strong coupling field, it renders the ring structure transparent to generated wave thus effectively enhancing the output of nonlinear frequency conversion process. At a fixed coupling strength, the output can be further enhanced by increasing the magnetic field while it shows an inverse relationship with pressure. These parameters, being externally controlled, provide an easy handle to control the output of quantum ring which can be used as frequency converter in communication networks.

  10. Electromagnetically induced transparency in a Zeeman-sublevels Λ-system of cold 87Rb atoms in free space

    NASA Astrophysics Data System (ADS)

    Xiaojun, Jiang; Haichao, Zhang; Yuzhu, Wang

    2016-03-01

    We report the experimental investigation of electromagnetically induced transparency (EIT) in a Zeeman-sublevels Λ-type system of cold 87Rb atoms in free space. We use the Zeeman substates of the hyperfine energy states 52S1/2, F = 2 and 52P3/2, F‧ = 2 of 87Rb D2 line to form a Λ-type EIT scheme. The EIT signal is obtained by scanning the probe light over 1 MHz in 4 ms with an 80 MHz arbitrary waveform generator. More than 97% transparency and 100 kHz EIT window are observed. This EIT scheme is suited for an application of pulsed coherent storage atom clock (Yan B, et al. 2009 Phys. Rev. A 79 063820). Project supported by the National Basic Research Program of China (Grant No. 2011CB921504) and the National Natural Science Foundation of China (Grant No. 91536107).

  11. Effect of buffer gas on an electromagnetically induced transparency in a ladder system using thermal rubidium vapor

    SciTech Connect

    Sargsyan, Armen; Sarkisyan, David; Krohn, Ulrich; Keaveney, James; Adams, Charles

    2010-10-15

    We report on the observation of electromagnetically induced transparency in a ladder system in the presence of a buffer gas. In particular, we study the 5S{sub 1/2}-5P{sub 3/2}-5D{sub 5/2} transition in thermal rubidium vapor with a neon buffer gas at a pressure of 6 Torr. In contrast to the line-narrowing effect of buffer gas on {Lambda} systems, we show that the presence of the buffer gas leads to an additional broadening of (34{+-}5) MHz, which suggests a cross section for Rb(5D{sub 5/2})-Ne of {sigma}{sub k}{sup (D)}=(23{+-}4)x10{sup -19} m{sup 2}. However, in the limit where the coupling Rabi frequency is larger than the collisional dephasing, a strong transparency feature can still be observed.

  12. Efficient reflection via four-wave mixing in a Doppler-free electromagnetically-induced-transparency gas system

    SciTech Connect

    Zhou, Hai-Tao; Wang, Dan; Zhang, Jun-Xiang; Wang, Da-Wei; Zhu, Shi-Yao

    2011-11-15

    We experimentally demonstrate the high-efficiency reflection of a probe field in {Lambda}-type three-level atoms of cesium vapor driven by two counterpropagating coupling fields. More than 60% of reflection efficiency is observed at the phase-matching angle. The underlying mechanism theoretically is investigated as the four-wave mixing is enhanced by the electromagnetically-induced transparency. Both of the two Doppler-free two-photon resonances (one for the probe and co-propagating fields, the other for the reflected and the counterpropagation fields) play an important role in satisfying the phase matching in the reflection direction. The phase compensation due to the anomalous dispersion and the decrease of effective absorption length in the atomic system allow the efficient reflection to be observed in a wide range of incident angles of the probe field and detunings of the coupling field.

  13. Direct measurement of excited-state dipole matrix elements using electromagnetically induced transparency in the hyperfine Paschen-Back regime

    NASA Astrophysics Data System (ADS)

    Whiting, Daniel J.; Keaveney, James; Adams, Charles S.; Hughes, Ifan G.

    2016-04-01

    Applying large magnetic fields to gain access to the hyperfine Paschen-Back regime can isolate three-level systems in a hot alkali metal vapors, thereby simplifying usually complex atom-light interactions. We use this method to make the first direct measurement of the |<5 P ||e r ||5 D >| matrix element in 87Rb. An analytic model with only three levels accurately models the experimental electromagnetically induced transparency spectra and extracted Rabi frequencies are used to determine the dipole matrix element. We measure |<5 P3 /2||e r ||5 D5 /2>| =(2.290 ±0 .002stat±0 .04syst) e a0 , which is in excellent agreement with the theoretical calculations of Safronova, Williams, and Clark [Phys. Rev. A 69, 022509 (2004), 10.1103/PhysRevA.69.022509].

  14. Ultra-wide band electromagnetic radiation does not affect UV-induced recombination and mutagenesis in yeast.

    PubMed

    Pakhomova, O N; Belt, M L; Mathur, S P; Lee, J C; Akyel, Y

    1998-01-01

    Cell samples of the yeast Saccharomyces cerevisiae were exposed to 100 J/m2 of 254 nm ultraviolet (UV) radiation followed by a 30 min treatment with ultra-wide band (UWB) electromagnetic pulses. The UWB pulses (101-104 kV/m, 1.0 ns width, 165 ps rise time) were applied at the repetition rates of 0 Hz (sham), 16 Hz, or 600 Hz. The effect of exposures was evaluated from the colony-forming ability of the cells on complete and selective media and the number of aberrant colonies. The experiments established no effect of UWB exposure on the UV-induced reciprocal and non-reciprocal recombination, mutagenesis, or cell survival.

  15. Transformation of electromagnetically induced transparency into absorption in a thermal potassium optical cell with spin preserving coating

    NASA Astrophysics Data System (ADS)

    Gozzini, S.; Lucchesini, A.; Marinelli, C.; Marmugi, L.; Gateva, S.; Tsvetkov, S.; Cartaleva, S.

    2016-03-01

    We report a new experimental approach where an order of magnitude enhancement of the electromagnetically induced absorption (EIA) resonance contrast, thus making it similar to that of the EIT resonance contrast is observed under the same conditions. The EIA signal results from the interaction of a weak probe beam with a ground state that has been driven by the pump (counter-propagating) beam. Probe absorption spectra are presented where the laser frequency is slowly detuned over the D1 line of 39K vapor contained in a cell with a PDMS antirelaxation coating. In addition to the frequency detuning, a magnetic field orthogonal to the laser beams is scanned around zero value at a higher rate. With both laser beams linearly polarized, an EIT resonance is observed. However, changing the pump beam polarization from linear to circular reverses the resonance signal from EIT to EIA.

  16. Analog of the electromagnetically-induced-transparency effect for two nanomechanical or micromechanical resonators coupled to a spin ensemble

    SciTech Connect

    Chang Yue; Sun, C. P.

    2011-05-15

    We study a hybrid nanomechanical system coupled to a spin ensemble as a quantum simulator to favor a quantum interference effect, electromagnetically induced transparency (EIT). This system consists of two nanomechanical resonators (NAMRs), each of which is coupled to a nuclear spin ensemble, and can be regarded as a crucial element in the quantum network of NAMR arrays coupled to spin ensembles. Here, the nuclear spin ensembles behave as a long-lived transducer to store and transfer the NAMRs' quantum information. This system shows the analog of the EIT effect under the driving of a probe microwave field. The double EIT phenomenon emerges in the large-N (the number of nuclei) limit within the low excitation approximation, because the interactions between the spin ensemble and the two NAMRs are reduced to the coupling of three harmonic oscillators. Furthermore, the group velocity is reduced in the two absorption windows.

  17. Plasma enhancement of femtosecond laser-induced electromagnetic pulses at metal and dielectric surfaces

    NASA Astrophysics Data System (ADS)

    Varma, Sanjay; Spicer, Jane; Brawley, Benjamin; Miragliotta, Joseph

    2014-05-01

    In a previous report, we have shown that the long wavelength, electromagnetic-pulsed (EMP) energy generated by ultrashort (38 fs) laser pulse ablation of a metal target is enhanced by an order of magnitude due to a preplasma generated by a different, 14-ns-long laser pulse. Here, we further investigate this EMP enhancement effect in a 2- to 16-GHz microwave region with different target materials and laser parameters. Specifically, we show a greater than two orders of magnitude enhancement to the EMP energy when the nanosecond and ultrashort laser pulses are coincident on a glass target, and greater than one order of magnitude enhancement when the pulses are coincident on a copper target.

  18. Pulsed electromagnetic wave exposure induces ultrastructural damage and upregulated expression of heat shock protein 70 in the rat adenohypophysis.

    PubMed

    Cheng, Kang; Ren, Dong-Qing; Yi, Jun; Zhou, Xiao-Guang; Yang, Wen-Qing; Chen, Yong-Bin; Li, Yong-Qiang; Huang, Xiao-Feng; Zeng, Gui-Ying

    2015-08-01

    The aim of the present study was to investigate the ultrastructural damage and the expression of heat shock protein 70 (HSP70) in the rat adenohypophysis following pulsed electromagnetic wave (PEMW) exposure. The rats were randomly divided into four groups: Sham PEMW exposure, 1 x 10(4) pulses of PEMW exposure, 1 x 10(5) pulses of PEMW exposure and 3 x 10(5) pulses of PEMW exposure. Whole body radiation of 1 x 10(4) pulses, 1 x 10(5) pulses and 3 x 10(5) pulses of PEMW were delivered with a field strength of 100 kV/m. The rats in each group (n=6 in each) were sacrificed 12, 24, 48 and 96 h after PEMW exposure. Transmission electron microscopy was then used to detect the ultrastructural changes and immunocytochemistry was used to examine the expression of HSP70. Cellular damage, including mitochondrial vacuolation occurred as early as 12 h after PEMW exposure.More severe cellular damages, including cell degeneration and necrosis, occurred 24 and 48 h after PEMW exposure. The PEMW-induced cellular damage increased as the number of PEMW pulses increased. In addition, the expression of HSP70 significantly increased following PEMW exposure and peaked after 12 h. These findings suggested that PEMW induced ultrastructural damages in the rat adenohypophysis and that HSP70 may have contributed to the PEMW-induced adenohypophyseal damage.

  19. Measurements of laser phase fluctuations induced by atmospheric turbulence over 2 km and 17.5 km distances.

    PubMed

    Ridley, Kevin D

    2011-09-10

    A laser heterodyne system was used to measure the phase fluctuations imposed on a 1.5 μm wavelength laser beam when double-passed over long atmospheric paths. Two distances were used: 2 and 17.5 km. Results are given for intensity scintillation, phase fluctuation time series and spectra, and phase structure function. The results are found to agree well with theory: the spectrum of phase fluctuations follows the 8/3 power law predicted for Kolmogorov turbulence over 3 orders of magnitude in frequency. The methods reported here could be used to investigate large-scale temperature variations in the atmosphere. PMID:21946989

  20. Bidirectional effect of electromagnetic fields on ketanserin-induced yawning in patients with multiple sclerosis: the role of melatonin.

    PubMed

    Sandyk, R

    1996-03-01

    5-HT2 receptors regulate sleep including yawning behavior. Ritanserin, a selective 5-HT2A receptor antagonist, increases the duration of slow wave in rats and humans. This effect is more pronounced during the light period when melatonin plasma levels are low; melatonin inhibits the sleep effects of ritanserin. These findings indicate that melatonin co-determines the effects of ritanserin on sleep. In a cohort of multiple sclerosis (MS) patients ketanserin, a selective 5-HT2A receptor antagonist, induces recurrent yawning particularly when administered in daytime. The frequency of yawning induced by the drug was modified by AC pulsed picotesla flux electromagnetic fields (EMFs) which affect melatonin secretion. Two MS patients are presented in whom the frequency of ketanserin-induced yawning was altered in opposite directions by these EMFs. The first patient, a 50 year old woman with a remitting-relapsing course, developed recurrent yawning and sleepiness after administration of ketanserin (10 mg, PO). Yawning was decreased dramatically during application of EMFs but was unaffected by a placebo EMFs treatment. The second patient, a 35 year old man with a chronic progressive course, manifested a single and brief yawn after administration of an equal dose of ketanserin. Yawning was increased dramatically during application of EMFs while remaining unchanged during a placebo EMFs treatment. These observations demonstrate a bidirectional effect of picotesla flux EMFs on ketanserin-induced yawning which may be related to differences in daytime melatonin plasma levels among MS patients. If validated by estimations of melatonin plasma levels in a larger cohort of patients the information derived from the effects of picotesla EMFs on ketanserin-induced yawning could be used to: (a) assess pineal melatonin functions in patients with MS; (b) indicate differences in pineal functions between male and female MS patients; and (c) indicate a relationship between plasma melatonin

  1. Phenotypic plasticity in growth and fecundity induced by strong population fluctuations affects reproductive traits of female fish.

    PubMed

    Karjalainen, Juha; Urpanen, Olli; Keskinen, Tapio; Huuskonen, Hannu; Sarvala, Jouko; Valkeajärvi, Pentti; Marjomäki, Timo J

    2016-02-01

    Fish are known for their high phenotypic plasticity in life-history traits in relation to environmental variability, and this is particularly pronounced among salmonids in the Northern Hemisphere. Resource limitation leads to trade-offs in phenotypic plasticity between life-history traits related to the reproduction, growth, and survival of individual fish, which have consequences for the age and size distributions of populations, as well as their dynamics and productivity. We studied the effect of plasticity in growth and fecundity of vendace females on their reproductive traits using a series of long-term incubation experiments. The wild parental fish originated from four separate populations with markedly different densities, and hence naturally induced differences in their growth and fecundity. The energy allocation to somatic tissues and eggs prior to spawning served as a proxy for total resource availability to individual females, and its effects on offspring survival and growth were analyzed. Vendace females allocated a rather constant proportion of available energy to eggs (per body mass) despite different growth patterns depending on the total resources in the different lakes; investment into eggs thus dictated the share remaining for growth. The energy allocation to eggs per mass was higher in young than in old spawners and the egg size and the relative fecundity differed between them: Young females produced more and smaller eggs and larvae than old spawners. In contrast to earlier observations of salmonids, a shortage of maternal food resources did not increase offspring size and survival. Vendace females in sparse populations with ample resources and high growth produced larger eggs and larvae. Vendace accommodate strong population fluctuations by their high plasticity in growth and fecundity, which affect their offspring size and consequently their recruitment and productivity, and account for their persistence and resilience in the face of high

  2. Quantum fluctuations of radiation pressure

    SciTech Connect

    Wu, Chun-Hsien; Ford, L. H.

    2001-08-15

    Quantum fluctuations of electromagnetic radiation pressure are discussed. We use an approach based on the quantum stress tensor to calculate the fluctuations in velocity and position of a mirror subjected to electromagnetic radiation. Our approach reveals that radiation pressure fluctuations in the case of a coherent state are due to a cross term between vacuum and state dependent terms in a stress tensor operator product. Thus observation of these fluctuations would entail experimental confirmation of this cross term. We first analyze the pressure fluctuations on a single, perfectly reflecting mirror, and then study the case of an interferometer. This involves a study of the effects of multiple bounces in one arm, as well as the correlations of the pressure fluctuations between arms of the interferometer. In all cases, our results are consistent with those previously obtained by Caves using different methods. We argue that the agreement between the different methods supports the reality of the cross term and justifies the methods used in its evaluation.

  3. Thermally induced chronic developmental stress in coho salmon: Integrating measures of mortality, early growth and fluctuating asymmetry

    USGS Publications Warehouse

    Campbell, W.B.; Emlen, J.M.; Hershberger, W.K.

    1998-01-01

    Developmental stability, or homeostasis, facilitates the production of consistent phenotypes by buffering against stress. Fluctuating asymmetry is produced by developmental instability and is manifested as small random departures from bilateral symmetry. Increased fluctuating asymmetry is thought to parallel compromised fitness, in part, because stress promotes energy dissipation. Compensatory energy expenditures within the organism are required to complete development, thus promoting instability through reductions in homeostasis. Increased heterozygosity may enhance developmental stability by reducing energy dissipation from stress through increased metabolic efficiency, possibly by providing greater flexibility in metabolic pathways. Traditionally, fluctuating asymmetry has been used as a bioindicator of chronic stress, provided that selective mortality of less fit individuals did not reduce stress-mediated increases in fluctuating asymmetry to background levels produced by natural developmental error, or create data inconsistencies such as higher asymmetry in groups exposed to lower stress. Unfortunately, absence of selective mortality and its effects, while often assumed, can be difficult to substantiate. We integrated measures of early growth, mortality, fluctuating asymmetry (mandibular pores, pectoral finrays, pelvic finrays, and gillrakers on the upper and lower arms of the first branchial arch) and directional asymmetry (branchiostegal rays) to assess chronic thermal stress (fluctuating temperatures as opposed to ambient temperatures) in developing eggs from two different coho salmon (Oncorhynchus kisutch) stocks and their reciprocal hybrids. Hybridization provided insight on the capacity of heterozygosity to reduce stress during development. Although egg losses were consistently higher in crosses exposed to fluctuating temperatures, egg mortality was predominantly a function of maternal stock of origin. Post-hatch losses were higher in crosses exposed to

  4. Oxidative changes and apoptosis induced by 1800-MHz electromagnetic radiation in NIH/3T3 cells.

    PubMed

    Hou, Qingxia; Wang, Minglian; Wu, Shuicai; Ma, Xuemei; An, Guangzhou; Liu, Huan; Xie, Fei

    2015-03-01

    To investigate the potential adverse effects of mobile phone radiation, we studied reactive oxygen species (ROS), DNA damage and apoptosis in mouse embryonic fibroblasts (NIH/3T3) after intermittent exposure (5 min on/10 min off, for various durations from 0.5 to 8 h) to an 1800-MHz GSM-talk mode electromagnetic radiation (EMR) at an average specific absorption rate of 2 W/kg. A 2',7'-dichlorofluorescin diacetate fluorescence probe was used to detect intracellular ROS levels, immunofluorescence was used to detect γH2AX foci as a marker for DNA damage, and flow cytometry was used to measure apoptosis. Our results showed a significant increase in intracellular ROS levels after EMR exposure and it reached the highest level at an exposure time of 1 h (p < 0.05) followed by a slight decrease when the exposure continued for as long as 8 h. No significant effect on the number of γH2AX was detected after EMR exposure. The percentage of late-apoptotic cells in the EMR-exposed group was significantly higher than that in the sham-exposed groups (p < 0.05). These results indicate that an 1800-MHz EMR enhances ROS formation and promotes apoptosis in NIH/3T3 cells.

  5. Intraspinal temperatures during regional deep hyperthermia induced by electromagnetic radiation in the Macaca mulatta.

    PubMed

    van der Zee, J; Wiersema, H D; Broekmeyer-Reurink, M P; van Rhoon, G C

    1997-01-01

    A capacitive ring system operating at 27 MHz was tested for temperature distribution in the abdominal cavity of the living Rhesus monkey. Catheters were introduced through the abdomen and their location checked after the experiment. During two of these experiments a catheter was also introduced into the intraspinal canal. Temperature distribution was rather homogeneous within the abdominal cavity. Core temperature remained 3-5 degrees C below intra-abdominal temperatures. The intraspinal temperature increase was of the same magnitude compared with intra-abdominal temperature increase. Similar findings in other species have been reported by others. It is concluded that during non-invasive induction of regional hyperthermia by electromagnetic radiation, where a high level of energy is directed close to the spine, the intraspinal temperatures may be increased as high as the temperatures within the surrounding tissues. The central nervous system may be relatively sensitive to hyperthermia and hyperthermia may sensitize the spinal cord to radiation. Therefore, when hyperthermia is targeted at areas near the spine, either alone or in combination with radiotherapy applied to the tolerance limit of the spinal cord, these findings will have to be taken into consideration.

  6. Neuroprotective effects of sevoflurane against electromagnetic pulse-induced brain injury through inhibition of neuronal oxidative stress and apoptosis.

    PubMed

    Deng, Bin; Xu, Hao; Zhang, Jin; Wang, Jin; Han, Li-Chun; Li, Li-Ya; Wu, Guang-Li; Hou, Yan-Ning; Guo, Guo-Zhen; Wang, Qiang; Sang, Han-Fei; Xu, Li-Xian

    2014-01-01

    Electromagnetic pulse (EMP) causes central nervous system damage and neurobehavioral disorders, and sevoflurane protects the brain from ischemic injury. We investigated the effects of sevoflurane on EMP-induced brain injury. Rats were exposed to EMP and immediately treated with sevoflurane. The protective effects of sevoflurane were assessed by Nissl staining, Fluoro-Jade C staining and electron microscopy. The neurobehavioral effects were assessed using the open-field test and the Morris water maze. Finally, primary cerebral cortical neurons were exposed to EMP and incubated with different concentration of sevoflurane. The cellular viability, lactate dehydrogenase (LDH) release, superoxide dismutase (SOD) activity and malondialdehyde (MDA) level were assayed. TUNEL staining was performed, and the expression of apoptotic markers was determined. The cerebral cortexes of EMP-exposed rats presented neuronal abnormalities. Sevoflurane alleviated these effects, as well as the learning and memory deficits caused by EMP exposure. In vitro, cell viability was reduced and LDH release was increased after EMP exposure; treatment with sevoflurane ameliorated these effects. Additionally, sevoflurane increased SOD activity, decreased MDA levels and alleviated neuronal apoptosis by regulating the expression of cleaved caspase-3, Bax and Bcl-2. These findings demonstrate that Sevoflurane conferred neuroprotective effects against EMP radiation-induced brain damage by inhibiting neuronal oxidative stress and apoptosis.

  7. Investigation and optimization of intraband electromagnetically induced transparency in strained InAs quantum dot/wetting layer structures

    NASA Astrophysics Data System (ADS)

    Parvizi, R.; Rezaei, G.

    2016-01-01

    In this work, effects of the shape and size on the optical properties and optimization of the intersubband electromagnetically induced transparency in the Infra-red region of three-dimensional strained truncated pyramid-shaped InAs/GaAs quantum dot (QD) were investigated in detail. More precisely, within the density matrix approach, the probe absorption and group velocity along with the refractive index of the medium were studied with respect to their dependence on the dephasing rates and the Rabi frequencies of the probe and coupling fields for different QD heights and wetting layer (WL) thicknesses. It is found that the slow-down factors, group index, and absorption coefficient are inversely proportional to the width of the transparency window and proportional to the depth of the transparency window. The optimized transparency window can be achieved by varying the dot height and the WL thickness such that the tall dots with thin WL thickness induce significant enhancements at a fixed resonant peak position of Rabi frequency of the coupling field. The physical reasons behind these interesting phenomena were also explained based on the polarized features of intersubband transitions.

  8. Strong Pitch-Angle Diffusion of the Ring Current Ions Induced by Electromagnetic ion Cyclotron Waves

    NASA Astrophysics Data System (ADS)

    Gamayunov, K. V.; Khazanov, G. V.

    2005-12-01

    Deep and intense circulation of the magnetospheric plasma during geomagnetic storm is building up an energy content of the terrestrial ring current (RC) to an unusually high level, and the RC intensity strongly influence the storm-time space weather. The recovery of Dst index takes place hours or days after Dst minimum, and is caused by the decay of magnetopause and magnetotail current systems, and removal of the RC ions due to charge exchange, convection through the dayside magnetopause, Coulomb scattering, RC interaction with electromagnetic ion cyclotron (EMIC) waves, and scattering by field-line curvature. During the early recovery phase, the RC loss rate is about one hour or less, and it is more rapid than charge exchange can support. Ion scattering into the loss cone by EMIC waves is believed to be responsible for such fast RC decay during this storm stage. However, most RC-EMIC wave interaction models do not predict the strong pitch-angle diffusion that is theoretically discussed and observed in the Earth magnetosphere (particularly by SEPS detectors on board of the POLAR satellite). In present work, we employ our self-consistent RC-EMIC wave model in order to study systematically the occurrence of the RC strong pitch-angle diffusion caused by interaction with waves during the May 1998 storm. Most of cases of the strong diffusion and of the intense EMIC waves are located in the afternoon-premidnight MLT sector at 3 < L < 6, and exhibit significant linear correlation. During the early recovery phase (at about 08 UT on May 4), the entire RC energy range (less than 450 keV) is subject to strong pitch-angle diffusion. Although the flux transitions between trapped zone and loss cone are steeper for higher energy RC protons than for main body of the distribution function, the pitch-angle distributions are highly isotropic for all energies both inside and outside of the loss cone.

  9. Fluctuations as stochastic deformation

    NASA Astrophysics Data System (ADS)

    Kazinski, P. O.

    2008-04-01

    A notion of stochastic deformation is introduced and the corresponding algebraic deformation procedure is developed. This procedure is analogous to the deformation of an algebra of observables like deformation quantization, but for an imaginary deformation parameter (the Planck constant). This method is demonstrated on diverse relativistic and nonrelativistic models with finite and infinite degrees of freedom. It is shown that under stochastic deformation the model of a nonrelativistic particle interacting with the electromagnetic field on a curved background passes into the stochastic model described by the Fokker-Planck equation with the diffusion tensor being the inverse metric tensor. The first stochastic correction to the Newton equations for this system is found. The Klein-Kramers equation is also derived as the stochastic deformation of a certain classical model. Relativistic generalizations of the Fokker-Planck and Klein-Kramers equations are obtained by applying the procedure of stochastic deformation to appropriate relativistic classical models. The analog of the Fokker-Planck equation associated with the stochastic Lorentz-Dirac equation is derived too. The stochastic deformation of the models of a free scalar field and an electromagnetic field is investigated. It turns out that in the latter case the obtained stochastic model describes a fluctuating electromagnetic field in a transparent medium.

  10. Fluctuations as stochastic deformation.

    PubMed

    Kazinski, P O

    2008-04-01

    A notion of stochastic deformation is introduced and the corresponding algebraic deformation procedure is developed. This procedure is analogous to the deformation of an algebra of observables like deformation quantization, but for an imaginary deformation parameter (the Planck constant). This method is demonstrated on diverse relativistic and nonrelativistic models with finite and infinite degrees of freedom. It is shown that under stochastic deformation the model of a nonrelativistic particle interacting with the electromagnetic field on a curved background passes into the stochastic model described by the Fokker-Planck equation with the diffusion tensor being the inverse metric tensor. The first stochastic correction to the Newton equations for this system is found. The Klein-Kramers equation is also derived as the stochastic deformation of a certain classical model. Relativistic generalizations of the Fokker-Planck and Klein-Kramers equations are obtained by applying the procedure of stochastic deformation to appropriate relativistic classical models. The analog of the Fokker-Planck equation associated with the stochastic Lorentz-Dirac equation is derived too. The stochastic deformation of the models of a free scalar field and an electromagnetic field is investigated. It turns out that in the latter case the obtained stochastic model describes a fluctuating electromagnetic field in a transparent medium.

  11. Electromagnetic Gauge Study of Laser-Induced Shock Waves in Aluminium Alloys

    NASA Astrophysics Data System (ADS)

    Peyre, P.; Fabbro, R.

    1995-12-01

    The laser-shock behaviour of three industrial aluminum alloys has been analyzed with an Electromagnetic Gauge Method (EMV) for measuring the velocity of the back free surface of thin foils submitted to plane laser irradiation. Surface pressure, shock decay in depth and Hugoniot Elastic Limits (HEL) of the materials were investigated with increasing thicknesses of foils to be shocked. First, surface peak pressures values as a function of laser power density gave a good agreement with conventional piezoelectric quartz measurements. Therefore, comparison of experimental results with computer simulations, using a 1D hydrodynamic Lagrangian finite difference code, were also in good accordance. Lastly, HEL values were compared with static and dynamic compressive tests in order to estimate the effects of a very large range of strain rates (10^{-3} s^{-1} to 10^6 s^{-1}) on the mechanical properties of the alloys. Cet article fait la synthèse d'une étude récente sur la caractérisation du comportement sous choc-laser de trois alliages d'aluminium largement utilisés dans l'industrie à travers la méthode dite de la jauge électromagnétique. Cette méthode permet de mesurer les vitesses matérielles induites en face arrière de plaques d'épaisseurs variables par un impact laser. La mise en vitesse de plaques nous a permis, premièrement, de vérifier la validité des pressions d'impact superficielles obtenues en les comparant avec des résultats antérieurs obtenus par des mesures sur capteurs quartz. Sur des plaques d'épaisseurs croissantes, nous avons caractérisé l'atténuation des ondes de choc en profondeur dans les alliages étudiés et mesuré les limites d'élasticité sous choc (pressions d'Hugoniot) des alliages. Les résultats ont été comparés avec succès à des simulations numériques grâce à un code de calcul monodimensionnel Lagrangien. Enfin, les valeurs des pressions d'Hugoniot mesurées ont permis de tracer l'évolution des contraintes d

  12. Fluctuations of fresh-saline water interface and of water table induced by sea tides in unconfined aquifers

    NASA Astrophysics Data System (ADS)

    Levanon, Elad; Shalev, Eyal; Yechieli, Yoseph; Gvirtzman, Haim

    2016-10-01

    This study examines effects of tides on fluctuations of the fresh-saline water interface and the groundwater level in unconfined coastal aquifers using a two-dimensional numerical model. The time-lags of the simulated hydraulic heads and salinities fluctuations compared to sea level fluctuations are analyzed using cross-correlation analysis. The results show that both the fresh-saline water interface and the groundwater level are affected harmonically by sea tide fluctuations. However, significantly different time-lags are obtained between the hydraulic head in the deeper and upper parts of the aquifer, and between head and salinity in the fresh-saline water interface. The hydraulic head in the deeper part of the aquifer responses much faster to sea level fluctuations than in the upper part. Surprisingly, a similar difference is detected between the time-lag of the hydraulic head in the fresh-saline water interface and the time-lag of the salinity at the same location. Furthermore, the time-lag of the salinity in the fresh-saline water interface is similar to the time-lag of the water table. We suggest a comprehensive mechanism for tidal influence on the coastal groundwater system, in which two main processes act simultaneously. First, sea tide causes a pressure head wave which propagates into the saturated zone of the aquifer, governed by the diffusivity of the aquifer (Ks/Ss). Second, this pressure head wave is attenuated at the water table due to the unsaturated flow within the capillary fringe which occurs during groundwater level oscillations. Because the tidal forcing acts on the sea-floor boundary and the attenuation of the groundwater level due to capillary effect acts on the groundwater table, two dimensional distributions of time-lag and hydraulic head amplitude are created. The capillary effect in the unsaturated zone plays a key role not only in the water table fluctuations as shown previously, but also on the salinity fluctuations in the fresh

  13. Ion-Specific Induced Fluctuations and Free Energetics of Aqueous Protein Hydrophobic Interfaces: Toward Connecting to Specific-Ion Behaviors at Aqueous Liquid–Vapor Interfaces

    PubMed Central

    2015-01-01

    We explore anion-induced interface fluctuations near protein–water interfaces using coarse-grained representations of interfaces as proposed by Willard and Chandler (J. Phys. Chem. B2010, 114, 1954−195820055377). We use umbrella sampling molecular dynamics to compute potentials of mean force along a reaction coordinate bridging the state where the anion is fully solvated and one where it is biased via harmonic restraints to remain at the protein–water interface. Specifically, we focus on fluctuations of an interface between water and a hydrophobic region of hydrophobin-II (HFBII), a 71 amino acid residue protein expressed by filamentous fungi and known for its ability to form hydrophobically mediated self-assemblies at interfaces such as a water/air interface. We consider the anions chloride and iodide that have been shown previously by simulations as displaying specific-ion behaviors at aqueous liquid–vapor interfaces. We find that as in the case of a pure liquid–vapor interface, at the hydrophobic protein–water interface, the larger, less charge-dense iodide anion displays a marginal interfacial stability compared with that of the smaller, more charge-dense chloride anion. Furthermore, consistent with the results at aqueous liquid–vapor interfaces, we find that iodide induces larger fluctuations of the protein–water interface than chloride. PMID:24701961

  14. Blast-induced electromagnetic fields in the brain from bone piezoelectricity.

    PubMed

    Lee, Ka Yan Karen; Nyein, Michelle K; Moore, David F; Joannopoulos, J D; Socrate, Simona; Imholt, Timothy; Radovitzky, Raul; Johnson, Steven G

    2011-01-01

    In this paper, we show that bone piezoelectricity-a phenomenon in which bone polarizes electrically in response to an applied mechanical stress and produces a short-range electric field-may be a source of intense blast-induced electric fields in the brain, with magnitudes and timescales comparable to fields with known neurological effects. We compute the induced charge density in the skull from stress data on the skull from a finite-element full-head model simulation of a typical IED-scale blast wave incident on an unhelmeted human head as well as a human head protected by a kevlar helmet, and estimate the resulting electric fields in the brain in both cases to be on the order of 10 V/m in millisecond pulses. These fields are more than 10 times stronger than the IEEE safety guidelines for controlled environments (IEEE Standards Coordinating Committee 28, 2002) and comparable in strength and timescale to fields from repetitive Transcranial Magnetic Stimulation (rTMS) that are designed to induce neurological effects (Wagner et al., 2006a). They can be easily measured by RF antennas, and may provide the means to design a diagnostic tool that records a quantitative measure of the head's exposure to blast insult.

  15. Blast-induced electromagnetic fields in the brain from bone piezoelectricity.

    PubMed

    Lee, Ka Yan Karen; Nyein, Michelle K; Moore, David F; Joannopoulos, J D; Socrate, Simona; Imholt, Timothy; Radovitzky, Raul; Johnson, Steven G

    2011-01-01

    In this paper, we show that bone piezoelectricity-a phenomenon in which bone polarizes electrically in response to an applied mechanical stress and produces a short-range electric field-may be a source of intense blast-induced electric fields in the brain, with magnitudes and timescales comparable to fields with known neurological effects. We compute the induced charge density in the skull from stress data on the skull from a finite-element full-head model simulation of a typical IED-scale blast wave incident on an unhelmeted human head as well as a human head protected by a kevlar helmet, and estimate the resulting electric fields in the brain in both cases to be on the order of 10 V/m in millisecond pulses. These fields are more than 10 times stronger than the IEEE safety guidelines for controlled environments (IEEE Standards Coordinating Committee 28, 2002) and comparable in strength and timescale to fields from repetitive Transcranial Magnetic Stimulation (rTMS) that are designed to induce neurological effects (Wagner et al., 2006a). They can be easily measured by RF antennas, and may provide the means to design a diagnostic tool that records a quantitative measure of the head's exposure to blast insult. PMID:20547228

  16. GRADFLEX: Fluctuations in Microgravity

    NASA Technical Reports Server (NTRS)

    Vailati, A.; Cerbino, R.; Mazzoni, S.; Giglio, M.; Nikolaenko, G.; Cannell, D. S.; Meyer, W. V.; Smart, A. E.

    2004-01-01

    We present the results of experimental investigations of gradient driven fluctuations induced in a liquid mixture with a concentration gradient and in a single-component fluid with a temperature gradient. We also describe the experimental apparatus being developed to carry out similar measurement under microgravity conditions.

  17. Spin-fluctuation induced non-Fermi-liquid behaviour with suppressed superconductivity in LiFe1-xCoxAs

    NASA Astrophysics Data System (ADS)

    Miao, Hu; Dai, Yaomin; Xing, Lingyi; Wang, Xiancheng; Wang, Pengshuai; Xiao, Hong; Qian, Tian; Richard, Pierre; Qiu, Xianggang; Yu, Weiqiang; Jin, Changqing; Wang, Ziqiang; Johnson, P. D.; Homes, C. C.; Ding, Hong

    We study a series of LiFe1-xCoxAs compounds with different Co concentrations by transport, optical spectroscopy, angle-resolved photoemission spectroscopy, and nuclear magnetic resonance. We observe a Fermi-liquid to non-Fermi-liquid to Fermi-liquid (FL-NFL-FL) crossover alongside a monotonic suppression of the superconductivity with increasing Co content. In parallel to the FL-NFL-FL crossover, we find that both the low-energy spin fluctuations and Fermi surface nesting are enhanced and then diminished, strongly suggesting that the NFL behaviour in LiFe1-xCoxAs is induced by low-energy spin fluctuations that are very likely tuned by Fermi surface nesting. Our study reveals a unique phase diagram of LiFe1-xCoxAs where the region of NFL is moved to the boundary of the superconducting phase, implying that they are probably governed by different mechanisms.

  18. Spin-Fluctuation-Induced Non-Fermi-Liquid Behavior with Suppressed Superconductivity in LiFe1 -xCoxAs

    NASA Astrophysics Data System (ADS)

    Dai, Y. M.; Miao, H.; Xing, L. Y.; Wang, X. C.; Wang, P. S.; Xiao, H.; Qian, T.; Richard, P.; Qiu, X. G.; Yu, W.; Jin, C. Q.; Wang, Z.; Johnson, P. D.; Homes, C. C.; Ding, H.

    2015-07-01

    We study a series of LiFe1 -xCox As compounds with different Co concentrations by transport, optical spectroscopy, angle-resolved photoemission spectroscopy, and nuclear magnetic resonance. We observe a Fermi-liquid to non-Fermi-liquid to Fermi-liquid (FL-NFL-FL) crossover alongside a monotonic suppression of the superconductivity with increasing Co content. In parallel to the FL-NFL-FL crossover, we find that both the low-energy spin fluctuations and Fermi surface nesting are enhanced and then diminished, strongly suggesting that the NFL behavior in LiFe1 -xCox As is induced by low-energy spin fluctuations that are very likely tuned by Fermi surface nesting. Our study reveals a unique phase diagram of LiFe1 -xCox As where the region of NFL is moved to the boundary of the superconducting phase, implying that they are probably governed by different mechanisms.

  19. Accommodative lag and fluctuations when optical aberrations are manipulated.

    PubMed

    Gambra, Enrique; Sawides, Lucie; Dorronsoro, Carlos; Marcos, Susana

    2009-06-09

    We evaluated the accommodative response to a stimulus moving from 0 to 6 D following a staircase function under natural, corrected, and induced optical aberrations, using an adaptive-optics (AO) electromagnetic deformable mirror. The accommodative response of the eye (through the mirror) and the change of aberrations were measured on 5 subjects using a Hartmann-Shack wavefront sensor operating at 12.8 Hz. Five conditions were tested: (1) natural aberrations, (2) AO correction of the unaccommodated state and induction (over 6-mm pupils) of (3) +1 microm and (4) -1 microm of spherical aberration and (5) -2 microm of vertical coma. Four subjects showed a better accommodative response with AO correction than with their natural aberrations. The induction of negative spherical aberration also produced a better accommodative response in the same subjects. Accommodative lag increased in all subjects when positive spherical aberration and coma were induced. Fluctuations of the accommodative response (computed during each 1-D period of steady accommodation) increased with accommodative response when high-order aberrations were induced. The largest fluctuations occurred for induced negative spherical aberration and the smallest for natural and corrected aberrations. The study demonstrates that aberrations influence accommodative lag and fluctuations of accommodation and that correcting aberrations improves rather than compromises the accommodative response.

  20. Noise-induced resonance-like phenomena in InP crystals embedded in fluctuating electric fields

    NASA Astrophysics Data System (ADS)

    Persano Adorno, D.; Pizzolato, N.; Spagnolo, B.

    2016-05-01

    We explore and discuss the complex electron dynamics inside a low-doped n-type InP bulk embedded in a sub-THz electric field, fluctuating for the superimposition of an external source of Gaussian correlated noise. The results presented in this study derive from numerical simulations obtained by means of a multi-valley Monte Carlo approach to simulate the nonlinear transport of electrons inside the semiconductor crystal. The electronic noise characteristics are statistically investigated by calculating the correlation function of the velocity fluctuations, its spectral density and the integrated spectral density, i.e. the total noise power, for different values of both amplitude and frequency of the driving oscillating electric field and for different correlation times of the field fluctuations. Our results show that the nonlinear response of electrons is strongly affected by the field fluctuations. In particular, crucially depending on the relationship between the correlation times of the external Gaussian noise and the timescales of complex phenomena involved in the electron dynamical behavior: (i) electrons self-organize among different valleys, giving rise to intrinsic noise suppression; (ii) this cooperative behavior causes the appearance of a resonance-like phenomenon in the noise spectra.

  1. Exposure to 1800 MHz radiofrequency electromagnetic radiation induces oxidative DNA base damage in a mouse spermatocyte-derived cell line.

    PubMed

    Liu, Chuan; Duan, Weixia; Xu, Shangcheng; Chen, Chunhai; He, Mindi; Zhang, Lei; Yu, Zhengping; Zhou, Zhou

    2013-03-27

    Whether exposure to radiofrequency electromagnetic radiation (RF-EMR) emitted from mobile phones can induce DNA damage in male germ cells remains unclear. In this study, we conducted a 24h intermittent exposure (5 min on and 10 min off) of a mouse spermatocyte-derived GC-2 cell line to 1800 MHz Global System for Mobile Communication (GSM) signals in GSM-Talk mode at specific absorption rates (SAR) of 1 W/kg, 2 W/kg or 4 W/kg. Subsequently, through the use of formamidopyrimidine DNA glycosylase (FPG) in a modified comet assay, we determined that the extent of DNA migration was significantly increased at a SAR of 4 W/kg. Flow cytometry analysis demonstrated that levels of the DNA adduct 8-oxoguanine (8-oxoG) were also increased at a SAR of 4 W/kg. These increases were concomitant with similar increases in the generation of reactive oxygen species (ROS); these phenomena were mitigated by co-treatment with the antioxidant α-tocopherol. However, no detectable DNA strand breakage was observed by the alkaline comet assay. Taking together, these findings may imply the novel possibility that RF-EMR with insufficient energy for the direct induction of DNA strand breaks may produce genotoxicity through oxidative DNA base damage in male germ cells.

  2. All-dielectric metasurface analogue of electromagnetically induced transparency [High Quality Factor Fano-Resonant All-Dielectric Metamaterials

    DOE PAGESBeta

    Yang, Yuanmu; Kravchenko, Ivan I.; Briggs, Dayrl P.; Valentine, Jason

    2014-12-16

    Fano-resonant plasmonic metamaterials and nanostructures have become a major focus of the nanophotonics fields over the past several years due their ability to produce high quality factor (Q-factor) resonances. The origin of such resonances is the interference between a broad and narrow resonance, ultimately allowing suppression of radiative damping. However, Fano-resonant plasmonic structures still suffer non-radiative damping due to Ohmic loss, ultimately limiting the achievable Q-factors to values less than ~10. Here, we report experimental demonstration of Fano-resonant silicon-based metamaterials that have a response that mimics the electromagnetically induced transparency (EIT) found in atomic systems. Due to extremely low absorptionmore » loss, a record-high quality factor (Q-factor) of 306 was experimentally observed. Furthermore, the unit cell of the metamaterial was designed with a feed-gap which results in strong local field enhancement in the surrounding medium resulting in strong light-matter interaction. This allows the metamaterial to serve as a refractive index sensor with a figure-of-merit (FOM) of 101, far exceeding the performance of previously demonstrated localized surface plasmon resonance sensors.« less

  3. All-dielectric metasurface analogue of electromagnetically induced transparency [High Quality Factor Fano-Resonant All-Dielectric Metamaterials

    SciTech Connect

    Yang, Yuanmu; Kravchenko, Ivan I.; Briggs, Dayrl P.; Valentine, Jason

    2014-12-16

    Fano-resonant plasmonic metamaterials and nanostructures have become a major focus of the nanophotonics fields over the past several years due their ability to produce high quality factor (Q-factor) resonances. The origin of such resonances is the interference between a broad and narrow resonance, ultimately allowing suppression of radiative damping. However, Fano-resonant plasmonic structures still suffer non-radiative damping due to Ohmic loss, ultimately limiting the achievable Q-factors to values less than ~10. Here, we report experimental demonstration of Fano-resonant silicon-based metamaterials that have a response that mimics the electromagnetically induced transparency (EIT) found in atomic systems. Due to extremely low absorption loss, a record-high quality factor (Q-factor) of 306 was experimentally observed. Furthermore, the unit cell of the metamaterial was designed with a feed-gap which results in strong local field enhancement in the surrounding medium resulting in strong light-matter interaction. This allows the metamaterial to serve as a refractive index sensor with a figure-of-merit (FOM) of 101, far exceeding the performance of previously demonstrated localized surface plasmon resonance sensors.

  4. Cavity electromagnetically induced transparency of driven-three-level atoms: A transparent window narrowing below a natural width

    NASA Astrophysics Data System (ADS)

    Bentley, Cleo L.; Liu, Jiaren; Liao, Yan

    2000-02-01

    Steady-state dynamics of a Λ atom in a ring cavity driven by two coherent fields are studied for arbitrary detunings, arbitrary incoherent pumping, and coherent driving intensities. Effects of both cavity and effective atom number on electromagnetically induced transparency (EIT) are pointed out. New physical pictures for cavity EIT are given in terms of collective cooperative coefficients and dispersion experienced by the probe. In the regime of smaller collective cooperative coefficients, an absorption-gain profile is reduced to that of a general EIT estimated by the imaginary part of a corresponding dipole moment, and its transparency window is directly proportional to power broadening, if the total Rabi frequency is large enough. But in the region of larger collective cooperative coefficients which means a dense atomic medium, longer optical path, or high-Q cavity, EIT is determined not only by the imaginary part but also by the real part of the corresponding dipole moment, which results in the possibility of observing an EIT central peak with a subnatural width, while there may be nearly no power broadening.

  5. Spatial transport of atomic coherence in electromagnetically induced absorption with a paraffin-coated Rb vapor cell.

    PubMed

    Lee, Yoon-Seok; Moon, Han Seb

    2014-06-30

    We report the spatial transport of spontaneously transferred atomic coherence (STAC) in electromagnetically induced absorption (EIA), which resulted from moving atoms with the STAC of the 5S(1/2) (F = 2)-5P(3/2) (F' = 3) transition of (87)Rb in a paraffin-coated vapor cell. In our experiment, two channels were spatially separate; the writing channel (WC) generated STAC in the EIA configuration, and the reading channel (RC) retrieved the optical field from the spatially transported STAC. Transported between the spatially separated positions, the fast light pulse of EIA in the WC and the delayed light pulse in the RC were observed. When the laser direction of the RC was counter-propagated in the direction of the WC, we observed direction reversal of the transported light pulse in the EIA medium. Furthermore, the delay time, the magnitude, and the width of the spatially transported light pulse were investigated with respect to the distance between the two channels. PMID:24977849

  6. Children and adults exposed to electromagnetic fields at the ICNIRP reference levels: theoretical assessment of the induced peak temperature increase

    NASA Astrophysics Data System (ADS)

    Bakker, J. F.; Paulides, M. M.; Neufeld, E.; Christ, A.; Kuster, N.; van Rhoon, G. C.

    2011-08-01

    To avoid potentially adverse health effects of electromagnetic fields (EMF), the International Commission on Non-Ionizing Radiation Protection (ICNIRP) has defined EMF reference levels. Restrictions on induced whole-body-averaged specific absorption rate (SARwb) are provided to keep the whole-body temperature increase (Tbody, incr) under 1 °C during 30 min. Additional restrictions on the peak 10 g spatial-averaged SAR (SAR10g) are provided to prevent excessive localized tissue heating. The objective of this study is to assess the localized peak temperature increase (Tincr, max) in children upon exposure at the reference levels. Finite-difference time-domain modeling was used to calculate Tincr, max in six children and two adults exposed to orthogonal plane-wave configurations. We performed a sensitivity study and Monte Carlo analysis to assess the uncertainty of the results. Considering the uncertainties in the model parameters, we found that a peak temperature increase as high as 1 °C can occur for worst-case scenarios at the ICNIRP reference levels. Since the guidelines are deduced from temperature increase, we used Tincr, max as being a better metric to prevent excessive localized tissue heating instead of localized peak SAR. However, we note that the exposure time should also be considered in future guidelines. Hence, we advise defining limits on Tincr, max for specified durations of exposure.

  7. Assessment of induced SAR in children exposed to electromagnetic plane waves between 10 MHz and 5.6 GHz

    NASA Astrophysics Data System (ADS)

    Bakker, J. F.; Paulides, M. M.; Christ, A.; Kuster, N.; van Rhoon, G. C.

    2010-06-01

    To avoid potentially adverse health effects of electromagnetic fields (EMF), the International Commission on Non-Ionizing Radiation Protection (ICNIRP) has defined EMF reference levels from the basic restrictions on the induced whole-body-averaged specific absorption rate (SARwb) and the peak 10 g spatial-averaged SAR (SAR10g). The objective of this study is to assess if the SAR in children remains below the basic restrictions upon exposure at the reference levels. Finite difference time domain (FDTD) modeling was used to calculate the SAR in six children and two adults when exposed to all 12 orthogonal plane wave configurations. A sensitivity study showed an expanded uncertainty of 53% (SARwb) and 58% (SAR10g) due to variations in simulation settings and tissue properties. In this study, we found that the basic restriction on the SARwb is occasionally exceeded for children, up to a maximum of 45% in small children. The maximum SAR10g values, usually found at body protrusions, remain under the limit for all scenarios studied. Our results are in good agreement with the literature, suggesting that the recommended ICNIRP reference levels may need fine tuning.

  8. Children and adults exposed to electromagnetic fields at the ICNIRP reference levels: theoretical assessment of the induced peak temperature increase.

    PubMed

    Bakker, J F; Paulides, M M; Neufeld, E; Christ, A; Kuster, N; van Rhoon, G C

    2011-08-01

    To avoid potentially adverse health effects of electromagnetic fields (EMF), the International Commission on Non-Ionizing Radiation Protection (ICNIRP) has defined EMF reference levels. Restrictions on induced whole-body-averaged specific absorption rate (SAR(wb)) are provided to keep the whole-body temperature increase (T(body, incr)) under 1 °C during 30 min. Additional restrictions on the peak 10 g spatial-averaged SAR (SAR(10g)) are provided to prevent excessive localized tissue heating. The objective of this study is to assess the localized peak temperature increase (T(incr, max)) in children upon exposure at the reference levels. Finite-difference time-domain modeling was used to calculate T(incr, max) in six children and two adults exposed to orthogonal plane-wave configurations. We performed a sensitivity study and Monte Carlo analysis to assess the uncertainty of the results. Considering the uncertainties in the model parameters, we found that a peak temperature increase as high as 1 °C can occur for worst-case scenarios at the ICNIRP reference levels. Since the guidelines are deduced from temperature increase, we used T(incr, max) as being a better metric to prevent excessive localized tissue heating instead of localized peak SAR. However, we note that the exposure time should also be considered in future guidelines. Hence, we advise defining limits on T(incr, max) for specified durations of exposure.

  9. Assessment of induced SAR in children exposed to electromagnetic plane waves between 10 MHz and 5.6 GHz.

    PubMed

    Bakker, J F; Paulides, M M; Christ, A; Kuster, N; van Rhoon, G C

    2010-06-01

    To avoid potentially adverse health effects of electromagnetic fields (EMF), the International Commission on Non-Ionizing Radiation Protection (ICNIRP) has defined EMF reference levels from the basic restrictions on the induced whole-body-averaged specific absorption rate (SAR(wb)) and the peak 10 g spatial-averaged SAR (SAR(10g)). The objective of this study is to assess if the SAR in children remains below the basic restrictions upon exposure at the reference levels. Finite difference time domain (FDTD) modeling was used to calculate the SAR in six children and two adults when exposed to all 12 orthogonal plane wave configurations. A sensitivity study showed an expanded uncertainty of 53% (SAR(wb)) and 58% (SAR(10g)) due to variations in simulation settings and tissue properties. In this study, we found that the basic restriction on the SAR(wb) is occasionally exceeded for children, up to a maximum of 45% in small children. The maximum SAR(10g) values, usually found at body protrusions, remain under the limit for all scenarios studied. Our results are in good agreement with the literature, suggesting that the recommended ICNIRP reference levels may need fine tuning.

  10. Spatial transport of atomic coherence in electromagnetically induced absorption with a paraffin-coated Rb vapor cell.

    PubMed

    Lee, Yoon-Seok; Moon, Han Seb

    2014-06-30

    We report the spatial transport of spontaneously transferred atomic coherence (STAC) in electromagnetically induced absorption (EIA), which resulted from moving atoms with the STAC of the 5S(1/2) (F = 2)-5P(3/2) (F' = 3) transition of (87)Rb in a paraffin-coated vapor cell. In our experiment, two channels were spatially separate; the writing channel (WC) generated STAC in the EIA configuration, and the reading channel (RC) retrieved the optical field from the spatially transported STAC. Transported between the spatially separated positions, the fast light pulse of EIA in the WC and the delayed light pulse in the RC were observed. When the laser direction of the RC was counter-propagated in the direction of the WC, we observed direction reversal of the transported light pulse in the EIA medium. Furthermore, the delay time, the magnitude, and the width of the spatially transported light pulse were investigated with respect to the distance between the two channels.

  11. Generation of atom-photon entangled states in atomic Bose-Einstein condensate via electromagnetically induced transparency

    SciTech Connect

    Kuang Leman; Zhou Lan

    2003-10-01

    In this paper, we present a method to generate continuous-variable-type entangled states between photons and atoms in atomic Bose-Einstein condensate (BEC). The proposed method involves an atomic BEC with three internal states, a weak quantized probe laser, and a strong classical coupling laser, which form a three-level {lambda}-shaped BEC system. We consider a situation where the BEC is in electromagnetically induced transparency with the coupling laser being much stronger than the probe laser. In this case, the upper and intermediate levels are unpopulated, so that their adiabatic elimination enables an effective two-mode model involving only the atomic field at the lowest internal level and the quantized probe laser field. Atom-photon quantum entanglement is created through laser-atom and interatomic interactions, and two-photon detuning. We show how to generate atom-photon entangled coherent states and entangled states between photon (atom) coherent states and atom-(photon-) macroscopic quantum superposition (MQS) states, and between photon-MQS and atom-MQS states.

  12. Dimethyl sulfoxide induced structural transformations and non-monotonic concentration dependence of conformational fluctuation around active site of lysozyme

    NASA Astrophysics Data System (ADS)

    Roy, Susmita; Jana, Biman; Bagchi, Biman

    2012-03-01

    Experimental studies have observed significant changes in both structure and function of lysozyme (and other proteins) on addition of a small amount of dimethyl sulfoxide (DMSO) in aqueous solution. Our atomistic molecular dynamic simulations of lysozyme in water-DMSO reveal the following sequence of changes on increasing DMSO concentration. (i) At the initial stage (around 5% DMSO concentration) protein's conformational flexibility gets markedly suppressed. From study of radial distribution functions, we attribute this to the preferential solvation of exposed protein hydrophobic residues by the methyl groups of DMSO. (ii) In the next stage (10-15% DMSO concentration range), lysozome partially unfolds accompanied by an increase both in fluctuation and in exposed protein surface area. (iii) Between 15-20% concentration ranges, both conformational fluctuation and solvent accessible protein surface area suddenly decrease again indicating the formation of an intermediate collapse state. These results are in good agreement with near-UV circular dichroism (CD) and fluorescence studies. We explain this apparently surprising behavior in terms of a structural transformation which involves clustering among the methyl groups of DMSO. (iv) Beyond 20% concentration of DMSO, the protein starts its final sojourn towards the unfolding state with further increase in conformational fluctuation and loss in native contacts. Most importantly, analysis of contact map and fluctuation near the active site reveal that both partial unfolding and conformational fluctuations are centered mostly on the hydrophobic core of active site of lysozyme. Our results could offer a general explanation and universal picture of the anomalous behavior of protein structure-function observed in the presence of cosolvents (DMSO, ethanol, tertiary butyl alcohol, dioxane) at their low concentrations.

  13. Tsunami-induced electromagnetic fields at the seafloor caused by earthquakes on both sides of the Kuril trench

    NASA Astrophysics Data System (ADS)

    Toh, H.; Hamano, Y.; Goto, T.

    2009-12-01

    It is generally known that electromagnetic (EM) fields can be generated by ocean currents moving through the Earth’s magnetic field. Theory of motional induction in the ocean (Longuet-Higgins, 1949; Sanford, 1971; Chave and Luther, 1991) indicates that observations of the induced EM fields by oceanic dynamo effect can reveal large scale oceanic flows, which is usually difficult by other methods. Especially, detection of tsunami propagation in off-shore areas is very important to predict accurate arrival times and tsunami heights at the sea shore. Unlike conventional tsunami sensors such as ocean bottom pressure gauges, simultaneous measurements of seafloor electric and magnetic fields are superior in detecting arrival directions and particle motions of tsunami flows by a single station, since EM measurements are essentially vector measurements. Recently, it was found, for the first time, that EM time-series from seafloor observatories in the northwest Pacific captured clear signals of the tsunami-induced EM variations. We have been operating one long-term seafloor electromagnetic station at a site called NWP in the northwest Pacific basin since August, 2001 and the other (WPB) in the west Philippine basin since June, 2006 (Toh et al., 2004; 2006). Both stations have successfully provided seafloor EM time-series for slightly less than 2000 days at NWP and more than 900 days at WPB so far. On the other hand, the three years from the end of 2004 were found seismically so active in the Pacific region that the time period covered large tsunami-generating earthquakes such as off the west coast of northern Sumatra earthquake occurred on December 26, 2004. Among the tsunami-generated earthquakes, we focused our analysis to a pair of earthquakes occurred successively on both sides of the Kuril Trench in November, 2006 and January, 2007. It turned out the seafloor EM station at NWP succeeded in capturing the tsunami-induced EM fields. The most dominant periods of the

  14. A non-linear induced polarization effect on transient electromagnetic soundings

    NASA Astrophysics Data System (ADS)

    Hallbauer-Zadorozhnaya, Valeriya Yu.; Santarato, Giovanni; Abu Zeid, Nasser; Bignardi, Samuel

    2016-10-01

    In a TEM survey conducted for characterizing the subsurface for geothermal purposes, a strong induced polarization effect was recorded in all collected data. Surprisingly, anomalous decay curves were obtained in part of the sites, whose shape depended on the repetition frequency of the exciting square waveform, i.e. on current pulse length. The Cole-Cole model, besides being not directly related to physical parameters of rocks, was found inappropriate to model the observed distortion, due to induced polarization, because this model is linear, i.e. it cannot fit any dependence on current pulse. This phenomenon was investigated and explained as due to the presence of membrane polarization linked to constrictivity of (fresh) water-saturated pores. An algorithm for mathematical modeling of TEM data was then developed to fit this behavior. The case history is then discussed: 1D inversion, which accommodates non-linear effects, produced models that agree quite satisfactorily with resistivity and chargeability models obtained by an electrical resistivity tomography carried out for comparison.

  15. Protective effect of procyanidins extracted from the lotus seedpod on immune function injury induced by extremely low frequency electromagnetic field.

    PubMed

    Zhang, Haihui; Cheng, Yanxiang; Luo, Xiaoping; Duan, Yuqing

    2016-08-01

    This study aimed to evaluate the protective effect of Lotus seedpod procyanidins (LSPCs) from extremely low frequency electromagnetic field (ELF-EMF) exposure (50Hz, 8mT, 28 days) and their protective mechanism against radiation damage. The results showed that LSPCs increased the organ index of mice and made the damaged blood-producing function and cytokine(INF-γ, TNF-α, IL-2, IL-6 and IL-10 in spleen) levels by ELF-EMF-irradiation recovered to normal appearance. And experimental results proved that dosing LSPCs inhibit more stagnation of splenocytes in G0/G1 phase caused by ELF-EMF, thus the spleen cells from G0/G1 phase to S phase shift, restore normal cell metabolism, promote the splenocytes proliferation, reduced the apoptosis of spleen cells, effective protect the damage induced by the ELF-EMF radiation. In addition, LSPCs prevented the decline of DNA content caused by ELF-EMF. Western blot determinated the levels of apoptosis genes including Bcl-2, Bax, Bcl-cl, Caspase-3 and Caspase-9. The results revealed that a significant suppression in Bcl-2 expression and increase in Bax, Caspase-3 and Caspase-9 expression in splenic cells in ELF-EMF group. However, LSPCs restored these changes. Taking these results together, it may be summarized that LSPCs could protect hematopoietic tissues and the immune system from ELF-EMF. And it may be hypothesized that ELF-EMF-induced apoptosis in splenocytes might occur via triggers the trans-activation of Bax and activates caspases-3 and -9, which then cleaves the death substrates, leading to apoptosis in splenocytes of mice treated with ELF-EMF. PMID:27470374

  16. Plasma parameters and electromagnetic forces induced by the magneto hydro dynamic interaction in a hypersonic argon flow experiment

    NASA Astrophysics Data System (ADS)

    Cristofolini, Andrea; Neretti, Gabriele; Borghi, Carlo A.

    2012-08-01

    This work proposes an experimental analysis on the magneto hydro dynamic (MHD) interaction induced by a magnetic test body immersed into a hypersonic argon flow. The characteristic plasma parameters are measured. They are related to the voltages arising in the Hall direction and to the variation of the fluid dynamic properties induced by the interaction. The tests have been performed in a hypersonic wind tunnel at Mach 6 and Mach 15. The plasma parameters are measured in the stagnation region in front of the nozzle of the wind tunnel and in the free stream region at the nozzle exit. The test body has a conical shape with the cone axis in the gas flow direction and the cone vertex against the flow. It is placed at the nozzle exit and is equipped with three permanent magnets. In the configuration adopted, the Faraday current flows in a closed loop completely immersed into the plasma of the shock layer. The electric field and the pressure variation due to MHD interaction have been measured on the test body walls. Microwave adsorption measurements have been used for the determination of the electron number density and the electron collision frequency. Continuum recombination radiation and line radiation emissions have been detected. The electron temperature has been determined by means of the spectroscopic data by using different methods. The electron number density has been also determined by means of the Stark broadening of Hα and the Hβ lines. Optical imaging has been utilized to visualize the pattern of the electric current distribution in the shock layer around the test body. The experiments show a considerable effect of the electromagnetic forces produced by the MHD interaction acting on the plasma flow around the test body. A comparison of the experimental data with simulation results shows a good agreement.

  17. Plasma parameters and electromagnetic forces induced by the magneto hydro dynamic interaction in a hypersonic argon flow experiment

    SciTech Connect

    Cristofolini, Andrea; Neretti, Gabriele; Borghi, Carlo A.

    2012-08-01

    This work proposes an experimental analysis on the magneto hydro dynamic (MHD) interaction induced by a magnetic test body immersed into a hypersonic argon flow. The characteristic plasma parameters are measured. They are related to the voltages arising in the Hall direction and to the variation of the fluid dynamic properties induced by the interaction. The tests have been performed in a hypersonic wind tunnel at Mach 6 and Mach 15. The plasma parameters are measured in the stagnation region in front of the nozzle of the wind tunnel and in the free stream region at the nozzle exit. The test body has a conical shape with the cone axis in the gas flow direction and the cone vertex against the flow. It is placed at the nozzle exit and is equipped with three permanent magnets. In the configuration adopted, the Faraday current flows in a closed loop completely immersed into the plasma of the shock layer. The electric field and the pressure variation due to MHD interaction have been measured on the test body walls. Microwave adsorption measurements have been used for the determination of the electron number density and the electron collision frequency. Continuum recombination radiation and line radiation emissions have been detected. The electron temperature has been determined by means of the spectroscopic data by using different methods. The electron number density has been also determined by means of the Stark broadening of H{sub {alpha}} and the H{sub {beta}} lines. Optical imaging has been utilized to visualize the pattern of the electric current distribution in the shock layer around the test body. The experiments show a considerable effect of the electromagnetic forces produced by the MHD interaction acting on the plasma flow around the test body. A comparison of the experimental data with simulation results shows a good agreement.

  18. [Comparative study of effect of infrared, submillimeter, and millimeter electromagnetic radiation on wing somatic mutations in Drosophila melanogaster induced by gamma-irradiation].

    PubMed

    Fedorov, V I; Pogodin, A S; Dubatolova, T D; Varlamov, A V; Leont'ev, K V; Khamoian, A G

    2001-01-01

    It was shown that the number of spontaneous and gamma-radiation-induced somatic mutations in wing cells of fruit flies (third instar larvae) exposed to laser irradiation of submillimeter range (lambda = 81.5 microns) was significantly lower than in control. Laser irradiation did not affect the number of recombinations. Exposure to laser radiation in the infrared range and electromagnetic waves of the millimeter range (lambda = 3.8 mm) enhanced the effect of gamma-irradiation.

  19. Casimir effect, quantum fluctuations and related topics

    NASA Astrophysics Data System (ADS)

    Hushwater, Velvel Shaia

    Casimir forces are the very long-range (retarded) forces between electrically neutral systems. Such forces may be thought of as arising from the quantum fluctuations of the electromagnetic field. Contrary to popular opinion such forces need not be attractive. After giving a foundation of the method of the change in the 'zero-point energy' we show how other methods to compute Casimir forces follow from it. We consider the repulsion between electric and magnetic dipoles induced by vacuum fluctuations of electromagnetic field. The calculation are made by the use of the Heisenberg picture operators and by the stochastic electrodynamics approach. We present a purely geometrical proof of the image method, and use it to discuss the Casimir interaction between an atom and a plate. We study the Casimir repulsion between a perfectly conducting and an infinitely permeable plate with the radiation pressure approach. This example illustrates how a repulsive force arises as a consequence of the redistribution of vacuum-field modes corresponding to specific boundary conditions. We show that result is independent of a cutoff function. Discussing the connection with perturbation theory, we prove the negativity of the leading order shift in the ground state. The Casimir effect supports the reality of the 'zero- point energy.' To clarify this we present a novel approach to quantum theory, based on the principle of the quantization of the ensemble-averaged action variable. This quantization leads to the probabilistic description of coordinates and momentum as random variables, which satisfy the uncertainty relation. Using such variables we show that the 'quantum momentum function' must satisfy the Riccati differential equation, which can be converted to the Schrodinger equation for the Ψ function. We derive also the form of basic operators and the rule for probabilities in quantum mechanics. We show that the approach leads to a simple interpretation of gauge invariance, and discuss

  20. Effects of extremely low frequency electromagnetic field (50 Hz) on pentylenetetrazol-induced seizures in mice.

    PubMed

    Fadakar, Kaveh; Saba, Valiallah; Farzampour, Shahrokh

    2013-06-01

    The electromagnetic fields (EMF) have various behavioral and biological effects on human body. There are growing concerns about the consequences of exposure to EMF. However, some studies have shown beneficial effects of these waves on human. In this paper, we study the effect of acute, sub acute and long-term exposure to 50 Hz, 0.1 mT magnetic fields (MF) on the seizure induction threshold in mice. 64 mice are used and divided into four groups. Eight mice in any group were selected to be exposed to MF for specific duration and the others were used as a control group. The duration of the applied exposures was as follows: (1) 1 day (acute), (2) 3 days (sub acute), (3) 2 weeks (sub acute), (4) 1 month (long term). The mice were exposed 2 h for a day. After exposure, the pentylentetrazol (PTZ) is injected to the mice to induce seizure and the needed dose for the seizure induction threshold is measured. In the acute exposure, the threshold to induce seizure in the exposed and sham-exposed groups was 44.25 and 46.5 mg, respectively, while the difference was not significant (p value = 0.5). In the sub acute exposure (3 days), the mean amount of drug to induce seizure was 47.38 mg in the exposed and 43.88 mg in the sham-exposed groups, however, the difference was not significant (p value = 0.3). The results were 52.38 and 46.75 mg after 2 weeks of exposure which were not significantly different either (p value = 0.2). After 1 month of exposure to MF, the threshold for the induction of seizure was significantly increased (p value < 0.05). The mean dosage to induce seizure in the exposed and control group was 54.3 and 45.75 mg, respectively. However, considering the p value, the difference in the seizure induction threshold between the exposed and sham-exposed groups after acute and sub acute exposure was not significant, analyzing the effects of acute, sub acute and long-term exposures totally indicates that increasing the exposure time increases the

  1. Observation of an electromagnetically induced change of absorption in multilevel rubidium atoms

    NASA Astrophysics Data System (ADS)

    Li, Yong-Qing; Jin, Shao-Zheng; Xiao, Min

    1995-03-01

    A 64.4% reduction in absorption at the rubidium D2 line is observed when a pumping field at 775.8 nm is tuned on resonance to the transition between the excited states 5P3/2 and 5D5/2. As the pumping field is tuned off resonance, an absorption peak appears at the side of the Doppler-broadened D2 line. This modification in absorption is related to pumping-induced atomic coherence in this three-level ladder-type system. This experiment is done in a Rb vapor cell at room temperature and with cw diode lasers for both pumping and probe beams in a Doppler-free configuration.

  2. Random numbers from vacuum fluctuations

    NASA Astrophysics Data System (ADS)

    Shi, Yicheng; Chng, Brenda; Kurtsiefer, Christian

    2016-07-01

    We implement a quantum random number generator based on a balanced homodyne measurement of vacuum fluctuations of the electromagnetic field. The digitized signal is directly processed with a fast randomness extraction scheme based on a linear feedback shift register. The random bit stream is continuously read in a computer at a rate of about 480 Mbit/s and passes an extended test suite for random numbers.

  3. Induced Polarization with Electromagnetic Coupling: 3D Spectral Imaging Theory, EMSP Project No. 73836

    SciTech Connect

    Morgan, F. Dale; Sogade, John

    2004-12-14

    This project was designed as a broad foundational study of spectral induced polarization (SIP) for characterization of contaminated sites. It encompassed laboratory studies of the effects of chemistry on induced polarization, development of 3D forward modeling and inversion codes, and investigations of inductive and capacitive coupling problems. In the laboratory part of the project a physico-chemical model developed in this project was used to invert laboratory IP spectra for the grain size and the effective grain size distribution of the sedimentary rocks as well as the formation factor, porosity, specific surface area, and the apparent fractal dimension. Furthermore, it was established that the IP response changed with the solution chemistry, the concentration of a given solution chemistry, valence of the constituent ions, and ionic radius. In the field part of the project, a 3D complex forward and inverse model was developed. It was used to process data acquired at two frequencies (1/16 Hz and 1/ 4Hz) in a cross-borehole configuration at the A-14 outfall area of the Savannah River Site (SRS) during March 2003 and June 2004. The chosen SRS site was contaminated with Tetrachloroethylene (TCE) and Trichloroethylene (PCE) that were disposed in this area for several decades till the 1980s. The imaginary conductivity produced from the inverted 2003 data correlated very well with the log10 (PCE) concentration derived from point sampling at 1 ft spacing in five ground-truth boreholes drilled after the data acquisition. The equivalent result for the 2004 data revealed that there were significant contaminant movements during the period March 2003 and June 2004, probably related to ground-truth activities and nearby remediation activities. Therefore SIP was successfully used to develop conceptual models of volume distributions of PCE/TCE contamination. In addition, the project developed non-polarizing electrodes that can be deployed in boreholes for years. A total of 28

  4. Parallel magnetic field-induced conductance fluctuations in GaAs/AlGaAs ballistic quantum dots.

    NASA Astrophysics Data System (ADS)

    Faniel, S.; Gustin, C.; Melinte, S.; Hackens, B.; Bayot, V.; Shayegan, M.

    2004-03-01

    We present magnetotransport measurements in ballistic quantum dots under a parallel magnetic field. The dots were fabricated on two different GaAs/AlGaAs quantum wells with thicknesses of 15 and and 45 nm and with one and two subbands occupied, respectively. The samples were patterned using e-beam lithography and wet etching. A Cr/Au electrostatic top gate was used in order to tune the width of the dot openings. The measurements were performed down to 300 mK with the magnetic field applied strictly parallel to the plane of the two-dimensional electron gas. For both dots, we observe universal conductance fluctuations and, in the case of the wide quantum well, a reduction of their amplitude at large magnetic field. We discuss these conductance fluctuations in terms of orbital effect(V.I. Fal'ko and T. Jungwirth, Phys Rev B 65), 081306 (2002) and magnetic subband depopulation.

  5. Modeling of wave-induced irradiance fluctuations at near-surface depths in the ocean: a comparison with measurements.

    PubMed

    You, Yu; Stramski, Dariusz; Darecki, Miroslaw; Kattawar, George W

    2010-02-20

    We develop a computationally fast radiative transfer model for simulating the fluctuations of the underwater downwelling irradiance E(d) at near-surface depths, which occur due to focusing of sunlight by wind-driven surface waves. The model is based on the hybrid matrix operator-Monte Carlo method, which was specifically designed for simulating radiative transfer in a coupled atmosphere-surface-ocean system involving a dynamic ocean surface. In the current version of the model, we use a simplified description of surface waves, which accounts for surface slope statistics, but not surface wave elevation, as a direct source of underwater light fluctuations. We compare the model results with measurements made in the Santa Barbara Channel. The model-simulated and measured time series of E(d)(t) show remarkable similarity. Major features of the probability distribution of instantaneous irradiance, the frequency content of irradiance fluctuations, and the statistical properties of light flashes produced by wave focusing are also generally consistent between the model simulations and measurements for a few near-surface depths and light wavelengths examined. Despite the simplification in the representation of surface waves, this model provides a reasonable first-order approximation to modeling the wave focusing effects at near-surface depths, which require high temporal and spatial resolution (of the order of 1 ms and 1 mm, respectively) to be adequately resolved.

  6. Influence of environment induced correlated fluctuations in electronic coupling on coherent excitation energy transfer dynamics in model photosynthetic systems

    NASA Astrophysics Data System (ADS)

    Huo, Pengfei; Coker, David F.

    2012-03-01

    Two-dimensional photon-echo experiments indicate that excitation energy transfer between chromophores near the reaction center of the photosynthetic purple bacterium Rhodobacter sphaeroides occurs coherently with decoherence times of hundreds of femtoseconds, comparable to the energy transfer time scale in these systems. The original explanation of this observation suggested that correlated fluctuations in chromophore excitation energies, driven by large scale protein motions could result in long lived coherent energy transfer dynamics. However, no significant site energy correlation has been found in recent molecular dynamics simulations of several model light harvesting systems. Instead, there is evidence of correlated fluctuations in site energy-electronic coupling and electronic coupling-electronic coupling. The roles of these different types of correlations in excitation energy transfer dynamics are not yet thoroughly understood, though the effects of site energy correlations have been well studied. In this paper, we introduce several general models that can realistically describe the effects of various types of correlated fluctuations in chromophore properties and systematically study the behavior of these models using general methods for treating dissipative quantum dynamics in complex multi-chromophore systems. The effects of correlation between site energy and inter-site electronic couplings are explored in a two state model of excitation energy transfer between the accessory bacteriochlorophyll and bacteriopheophytin in a reaction center system and we find that these types of correlated fluctuations can enhance or suppress coherence and transfer rate simultaneously. In contrast, models for correlated fluctuations in chromophore excitation energies show enhanced coherent dynamics but necessarily show decrease in excitation energy transfer rate accompanying such coherence enhancement. Finally, for a three state model of the Fenna-Matthews-Olsen light

  7. ELECTROMAGNETIC PUMP

    DOEpatents

    Pulley, O.O.

    1954-08-17

    This patent reiates to electromagnetic pumps for electricity-conducting fluids and, in particular, describes several modifications for a linear conduction type electromagnetic interaction pump. The invention resides in passing the return conductor for the current traversing the fiuid in the duct back through the gap in the iron circuit of the pump. Both the maximum allowable pressure and the efficiency of a linear conduction electromagnetic pump are increased by incorporation of the present invention.

  8. Understanding possible electromagnetic counterparts to loud gravitational wave events: Binary black hole effects on electromagnetic fields

    SciTech Connect

    Palenzuela, Carlos; Lehner, Luis; Yoshida, Shin

    2010-04-15

    In addition to producing loud gravitational waves, the dynamics of a binary black hole system could induce emission of electromagnetic radiation by affecting the behavior of plasmas and electromagnetic fields in their vicinity. We study how the electromagnetic fields are affected by a pair of orbiting black holes through the merger. In particular, we show how the binary's dynamics induce a variability in possible electromagnetically induced emissions as well as an enhancement of electromagnetic fields during the late-merge and merger epochs. These time dependent features will likely leave their imprint in processes generating detectable emissions and can be exploited in the detection of electromagnetic counterparts of gravitational waves.

  9. Fluctuating shells under pressure

    PubMed Central

    Paulose, Jayson; Vliegenthart, Gerard A.; Gompper, Gerhard; Nelson, David R.

    2012-01-01

    Thermal fluctuations strongly modify the large length-scale elastic behavior of cross-linked membranes, giving rise to scale-dependent elastic moduli. Whereas thermal effects in flat membranes are well understood, many natural and artificial microstructures are modeled as thin elastic shells. Shells are distinguished from flat membranes by their nonzero curvature, which provides a size-dependent coupling between the in-plane stretching modes and the out-of-plane undulations. In addition, a shell can support a pressure difference between its interior and its exterior. Little is known about the effect of thermal fluctuations on the elastic properties of shells. Here, we study the statistical mechanics of shape fluctuations in a pressurized spherical shell, using perturbation theory and Monte Carlo computer simulations, explicitly including the effects of curvature and an inward pressure. We predict novel properties of fluctuating thin shells under point indentations and pressure-induced deformations. The contribution due to thermal fluctuations increases with increasing ratio of shell radius to thickness and dominates the response when the product of this ratio and the thermal energy becomes large compared with the bending rigidity of the shell. Thermal effects are enhanced when a large uniform inward pressure acts on the shell and diverge as this pressure approaches the classical buckling transition of the shell. Our results are relevant for the elasticity and osmotic collapse of microcapsules. PMID:23150558

  10. The CB1 cannabinoid receptor agonist reduces L-DOPA-induced motor fluctuation and ERK1/2 phosphorylation in 6-OHDA-lesioned rats.

    PubMed

    Song, Lu; Yang, Xinxin; Ma, Yaping; Wu, Na; Liu, Zhenguo

    2014-01-01

    The dopamine precursor L-3,4-dihydroxyphenylalanine (L-DOPA) has been used as an effective drug for treating dopamine depletion-induced Parkinson's disease (PD). However, long-term administration of L-DOPA produces motor complications. L-DOPA has also been found to modify the two key signaling cascades, protein kinase A/dopamine- and cAMP-regulated phosphoprotein of 32 kDa (DARPP-32) and extracellular signal-regulated kinases 1 and 2 (ERK1/2), in striatal neurons, which are thought to play a pivotal role in forming motor complications. In the present study, we tested the possible effect of a CB1 cannabinoid receptor agonist on L-DOPA-stimulated abnormal behavioral and signaling responses in vivo. Intermittent L-DOPA administration for 3 weeks induced motor fluctuation in a rat model of PD induced by intrastriatal infusion of dopamine-depleting neurotoxin 6-hydroxydopamine (6-OHDA). A single injection of a CB1 cannabinoid receptor agonist WIN-55,212-2 had no effect on L-DOPA-induced motor fluctuation. However, chronic injections of WIN-55,212-2 significantly attenuated abnormal behavioral responses to L-DOPA in 6-OHDA-lesioned rats. Similarly, chronic injections of WIN-55,212-2 influence the L-DOPA-induced alteration of DARPP-32 and ERK1/2 phosphorylation status in striatal neurons. These data provide evidence for the active involvement of CB1 cannabinoid receptors in the regulation of L-DOPA action during PD therapy.

  11. The CB1 cannabinoid receptor agonist reduces L-DOPA-induced motor fluctuation and ERK1/2 phosphorylation in 6-OHDA-lesioned rats

    PubMed Central

    Song, Lu; Yang, Xinxin; Ma, Yaping; Wu, Na; Liu, Zhenguo

    2014-01-01

    The dopamine precursor L-3,4-dihydroxyphenylalanine (L-DOPA) has been used as an effective drug for treating dopamine depletion-induced Parkinson’s disease (PD). However, long-term administration of L-DOPA produces motor complications. L-DOPA has also been found to modify the two key signaling cascades, protein kinase A/dopamine- and cAMP-regulated phosphoprotein of 32 kDa (DARPP-32) and extracellular signal-regulated kinases 1 and 2 (ERK1/2), in striatal neurons, which are thought to play a pivotal role in forming motor complications. In the present study, we tested the possible effect of a CB1 cannabinoid receptor agonist on L-DOPA-stimulated abnormal behavioral and signaling responses in vivo. Intermittent L-DOPA administration for 3 weeks induced motor fluctuation in a rat model of PD induced by intrastriatal infusion of dopamine-depleting neurotoxin 6-hydroxydopamine (6-OHDA). A single injection of a CB1 cannabinoid receptor agonist WIN-55,212-2 had no effect on L-DOPA-induced motor fluctuation. However, chronic injections of WIN-55,212-2 significantly attenuated abnormal behavioral responses to L-DOPA in 6-OHDA-lesioned rats. Similarly, chronic injections of WIN-55,212-2 influence the L-DOPA-induced alteration of DARPP-32 and ERK1/2 phosphorylation status in striatal neurons. These data provide evidence for the active involvement of CB1 cannabinoid receptors in the regulation of L-DOPA action during PD therapy. PMID:25395834

  12. Slow and stored light under conditions of electromagnetically induced transparency and four wave mixing in an atomic vapor

    NASA Astrophysics Data System (ADS)

    Phillips, Nathaniel Blair

    The recent prospect of efficient, reliable, and secure quantum communication relies on the ability to coherently and reversibly map nonclassical states of light onto long-lived atomic states. A promising technique that accomplishes this employs Electromagnetically Induced Transparency (EIT), in which a strong classical control field modifies the optical properties of a weak signal field in such a way that a previously opaque medium becomes transparent to the signal field. The accompanying steep dispersion in the index of refraction allows for pulses of light to be decelerated, then stored as an atomic excitation, and later retrieved as a photonic mode. This dissertation presents the results of investigations into methods for optimizing the memory efficiency of this process in an ensemble of hot Rb atoms. We have experimentally demonstrated the effectiveness of two protocols for yielding the best memory efficiency possible at a given atomic density. Improving memory efficiency requires operation at higher optical depths, where undesired effects such as four-wave mixing (FWM) become enhanced and can spontaneously produce a new optical mode (Stokes field). We present the results of experimental and theoretical investigations of the FWM-EIT interaction under continuous-wave (cw), slow light, and stored light conditions. In particular, we provide evidence that indicates that while a Stokes field is generated upon retrieval of the signal field, any information originally encoded in a seeded Stokes field is not independently preserved during the storage process. We present a simple model that describes the propagation dynamics and provides an intuitive description of the EIT-FWM process.

  13. Probing Nanoscale Surface Enhanced Raman Scattering Fluctuation Dynamics using Correlated AFM and Confocal Ultramicroscopy

    SciTech Connect

    Suh, Yung D.; Schenter, Gregory K.; Zhu, Leyun; Lu, H PETER.

    2003-10-01

    We have studied the laser-excitation-intensity-dependent and Ag-nanocluster interstitial-site-dependent SERS intensity fluctuations under low molecule surface coverage of rhodamine 6G and cytochrome c. a new two-channel photon time-stamping system coupled with atomic force microscopic (AFM), Raman spectroscopic, and imaging microscopy was developed and applied to record Raman intensity fluctuation trajectories at sub-microsecond resolution correlated with in-situ characterization of the nanoparticle clusters. Our experimental results suggest that the nanoconfinement of the local electromagnetic-field enhancement and the interaction of the local field with the molecules, presumably under rotational motions, result in nano-Raman fluctuations. The SERS spectral fluctuation was pertinent to the nanoscale local enhancement and local interaction of the molecules with the surface when the number of molecules to contribute the microscopic Raman signal collected from a diffraction-limited focus spot. The SERS fluctuation dynamics were both photo-induced and spontaneous for rhodamine 6G, but only the photo-induced interstitial sites with heterogeneous geometries. To interpret the observed nano-SERS fluctuation dynamics, we used computer simulation of optical multiple scattering, based on multi-sphere scattering Mie theory, and rotational diffusion of molecules at an interstitial site, based on a random walk in orientation space.

  14. Phase speed saturation of Farley-Buneman waves due to stochastic, self-induced fluctuations in the background flow

    NASA Astrophysics Data System (ADS)

    Rojas, E. L.; Young, M. A.; Hysell, D. L.

    2016-06-01

    The phase speed saturation of Farley-Buneman waves is studied as an interaction with the random turbulent fluctuations in the background. We used the formalism of stochastic differential equations to model the complex interactions with a linearized system plus a stochastic term. Applying an averaging technique, we can obtain an augmented linear system that depends on the random behavior of the waves. The results show that following this approach we can obtain phase velocities that saturate close to the ion acoustic speed (Cs). This approach seems promising for the study of the influence of plasma turbulence generated by different kinds of instabilities on the mean state of the ionosphere.

  15. On the Coupling Between Gravity and Electromagnetism Through Quantum Vacuum

    NASA Astrophysics Data System (ADS)

    Maxmilian Caligiuri, Luigi

    The possible unification between electromagnetism and gravity is one of greatest challenges in Physics. According to the so-called "Zero-Point Field Inertia Hypothesis" inertia and gravity could be interpreted, through a semi-classical approach, as the electromagnetic reaction force to the interaction between charged elementary particles contained in a body and quantum vacuum fluctuating electromagnetic modes interacting with them. In a late paper this author, sharing this idea as a starting point but moving within the framework of QFT, proposed a novel model in which inertia emerges from a superradiant phase transition of quantum vacuum due to the coherent interaction between matter-wave and em fields quanta. In both the approaches a resonant-type mechanism is involved in describing the dynamic interaction between a body and ZPF in which it is "immersed". So it is expected that if a change in the related resonance frequency is induced by modifying the boundary conditions as, for example, through the introduction of a strong electromagnetic field of suitable frequency, the inertial and gravitational mass associated to that body will also be modified. In this paper we have shown, also basing on previous results and starting from the assumption that not only inertia but also gravitational constant G could be truly a function of quantum vacuum energy density, that the application of an electromagnetic field is able to modify the ZPF energy density and, consequently, the value of G in the region of space containing a particle or body. This result particularly suggests a novel interpretation of the coupling between electromagnetic and gravitational interaction ruled by the dynamical features of ZPF energy. Apart from its theoretical consequences, this model could also proposes new paths towards the so-called ZPF-induced gravitation with very interesting applications to advanced technology.

  16. Electromagnetic Attraction.

    ERIC Educational Resources Information Center

    Milson, James L.

    1990-01-01

    Three activities involving electromagnetism are presented. Discussed are investigations involving the construction of an electromagnet, the effect of the number of turns of wire in the magnet, and the effect of the number of batteries in the circuit. Extension activities are suggested. (CW)

  17. Variance of phase fluctuations of waves propagating through a random medium

    NASA Technical Reports Server (NTRS)

    Chu, Nelson C.; Kong, Jin AU; Yueh, Simon H.; Nghiem, Son V.; Fleischman, Jack G.; Ayasli, Serpil; Shin, Robert T.

    1992-01-01

    As an electromagnetic wave propagates through a random scattering medium, such as a forest, its energy is attenuated and random phase fluctuations are induced. The magnitude of the random phase fluctuations induced is important in estimating how well a Synthetic Aperture Radar (SAR) can image objects within the scattering medium. The two-layer random medium model, consisting of a scattering layer between free space and ground, is used to calculate the variance of the phase fluctuations induced between a transmitter located above the random medium and a receiver located below the random medium. The scattering properties of the random medium are characterized by a correlation function of the random permittivity fluctuations. The effective permittivity of the random medium is first calculated using the strong fluctuation theory, which accounts for large permittivity fluctuations of the scatterers. The distorted Born approximation is used to calculate the first-order scattered field. A perturbation series for the phase of the received field in the Rytov approximation is then introduced and the variance of the phase fluctuations is also calculated assuming that the transmitter and receiver are in the paraxial limit of the random medium, which allows an analytic solution to be obtained. Results are compared using the paraxial approximation, scalar Green's function formulation, and dyadic Green's function formulation. The effects studied are the dependence of the variance of the phase fluctuations on receiver location in lossy and lossless regions, medium thickness, correlation length and fractional volume of scatterers, depolarization of the incident wave, ground layer permittivity, angle of incidence, and polarization.

  18. Theoretical studies on rapid fluctuations in solar flares

    NASA Technical Reports Server (NTRS)

    Vlahos, Loukas

    1986-01-01

    Rapid fluctuations in the emission of solar bursts may have many different origins e.g., the acceleration process can have a pulsating structure, the propagation of energetic electrons and ions can be interrupted from plasma instabilities and finally the electromagnetic radiation produced by the interaction of electrostatic and electromagnetic waves may have a pulsating behavior in time. In two separate studies the conditions for rapid fluctuations in solar flare driven emission were analyzed.

  19. Fluctuation-induced first-order phase transitions in type-1.5 superconductors in zero external field

    NASA Astrophysics Data System (ADS)

    Meier, Hannes; Babaev, Egor; Wallin, Mats

    2015-03-01

    In a single-component Ginzburg-Landau model which possesses thermodynamically stable vortex excitations, the zero-field superconducting phase transition is second order even when fluctuations are included. Beyond the mean-field approximation the transition is described in terms of proliferation of vortex loops. Here we determine the order of the superconducting transition in an effective 3D vortex-loop model for the recently proposed multiband type-1.5 superconductors. The vortex interaction is nonmonotonic, i.e., exponentially screened and attractive at large separations, and short-range repulsive. We show that the details of the vortex interaction, despite its short-range nature, can lead to very different properties of the superconducting transition than found in type-1 and type-2 systems. Namely, the type-1.5 regime with nonmonotonic intervortex interaction can have a first-order vortex-driven phase transition not found in the single-band case.

  20. Shear-induced concentration fluctuations and form factor changes in polymer solution in the good-solvent regime.

    PubMed

    Morfin, I; Lindner, P; Boué, F

    2004-09-01

    Small-Angle Scattering from sheared semidilute polymer solution is reported in the good-solvent regime, at variance with former light and neutron measurements in the theta regime. First, concentration fluctuations are observed: the scattering increases noticeably along the flow at low q, but at variance with former results for the theta-solvent regime, no demixing is observed at higher shear. Here, instead, the effects follow a time-temperature superposition and saturate above a Weissenberg number around 5, like the stress which is known to present a plateau for these systems. Using the Zero Average Contrast technique, we have also measured the form factor, which displays the same saturation effect reaching a deformation ratio of the order of 2. These results agree with the Convective Constraint Release models (CCR) elaborated in order to predict the stress effects in the non-Newtonian regime (Marrucci-Ianniruberto) and their extension predicting also the scattering (Likhtman-Milner-McLeish).

  1. Protein-fluctuation-induced water-pore formation in ion channel voltage-sensor translocation across a lipid bilayer membrane

    NASA Astrophysics Data System (ADS)

    Rajapaksha, Suneth P.; Pal, Nibedita; Zheng, Desheng; Lu, H. Peter

    2015-11-01

    We have applied a combined fluorescence microscopy and single-ion-channel electric current recording approach, correlating with molecular dynamics (MD) simulations, to study the mechanism of voltage-sensor domain translocation across a lipid bilayer. We use the colicin Ia ion channel as a model system, and our experimental and simulation results show the following: (1) The open-close activity of an activated colicin Ia is not necessarily sensitive to the amplitude of the applied cross-membrane voltage when the cross-membrane voltage is around the resting potential of excitable membranes; and (2) there is a significant probability that the activation of colicin Ia occurs by forming a transient and fluctuating water pore of ˜15 Å diameter in the lipid bilayer membrane. The location of the water-pore formation is nonrandom and highly specific, right at the insertion site of colicin Ia charged residues in the lipid bilayer membrane, and the formation is intrinsically associated with the polypeptide conformational fluctuations and solvation dynamics. Our results suggest an interesting mechanistic pathway for voltage-sensitive ion channel activation, and specifically for translocation of charged polypeptide chains across the lipid membrane under a transmembrane electric field: the charged polypeptide domain facilitates the formation of hydrophilic water pore in the membrane and diffuses through the hydrophilic pathway across the membrane; i.e., the charged polypeptide chain can cross a lipid membrane without entering into the hydrophobic core of the lipid membrane but entirely through the aqueous and hydrophilic environment to achieve a cross-membrane translocation. This mechanism sheds light on the intensive and fundamental debate on how a hydrophilic and charged peptide domain diffuses across the biologically inaccessible high-energy barrier of the hydrophobic core of a lipid bilayer: The peptide domain does not need to cross the hydrophobic core to move across a

  2. Protein-fluctuation-induced water-pore formation in ion channel voltage-sensor translocation across a lipid bilayer membrane.

    PubMed

    Rajapaksha, Suneth P; Pal, Nibedita; Zheng, Desheng; Lu, H Peter

    2015-01-01

    We have applied a combined fluorescence microscopy and single-ion-channel electric current recording approach, correlating with molecular dynamics (MD) simulations, to study the mechanism of voltage-sensor domain translocation across a lipid bilayer. We use the colicin Ia ion channel as a model system, and our experimental and simulation results show the following: (1) The open-close activity of an activated colicin Ia is not necessarily sensitive to the amplitude of the applied cross-membrane voltage when the cross-membrane voltage is around the resting potential of excitable membranes; and (2) there is a significant probability that the activation of colicin Ia occurs by forming a transient and fluctuating water pore of ∼15 Å diameter in the lipid bilayer membrane. The location of the water-pore formation is nonrandom and highly specific, right at the insertion site of colicin Ia charged residues in the lipid bilayer membrane, and the formation is intrinsically associated with the polypeptide conformational fluctuations and solvation dynamics. Our results suggest an interesting mechanistic pathway for voltage-sensitive ion channel activation, and specifically for translocation of charged polypeptide chains across the lipid membrane under a transmembrane electric field: the charged polypeptide domain facilitates the formation of hydrophilic water pore in the membrane and diffuses through the hydrophilic pathway across the membrane; i.e., the charged polypeptide chain can cross a lipid membrane without entering into the hydrophobic core of the lipid membrane but entirely through the aqueous and hydrophilic environment to achieve a cross-membrane translocation. This mechanism sheds light on the intensive and fundamental debate on how a hydrophilic and charged peptide domain diffuses across the biologically inaccessible high-energy barrier of the hydrophobic core of a lipid bilayer: The peptide domain does not need to cross the hydrophobic core to move across a

  3. Protein-fluctuation-induced water-pore formation in ion channel voltage-sensor translocation across a lipid bilayer membrane.

    PubMed

    Rajapaksha, Suneth P; Pal, Nibedita; Zheng, Desheng; Lu, H Peter

    2015-01-01

    We have applied a combined fluorescence microscopy and single-ion-channel electric current recording approach, correlating with molecular dynamics (MD) simulations, to study the mechanism of voltage-sensor domain translocation across a lipid bilayer. We use the colicin Ia ion channel as a model system, and our experimental and simulation results show the following: (1) The open-close activity of an activated colicin Ia is not necessarily sensitive to the amplitude of the applied cross-membrane voltage when the cross-membrane voltage is around the resting potential of excitable membranes; and (2) there is a significant probability that the activation of colicin Ia occurs by forming a transient and fluctuating water pore of ∼15 Å diameter in the lipid bilayer membrane. The location of the water-pore formation is nonrandom and highly specific, right at the insertion site of colicin Ia charged residues in the lipid bilayer membrane, and the formation is intrinsically associated with the polypeptide conformational fluctuations and solvation dynamics. Our results suggest an interesting mechanistic pathway for voltage-sensitive ion channel activation, and specifically for translocation of charged polypeptide chains across the lipid membrane under a transmembrane electric field: the charged polypeptide domain facilitates the formation of hydrophilic water pore in the membrane and diffuses through the hydrophilic pathway across the membrane; i.e., the charged polypeptide chain can cross a lipid membrane without entering into the hydrophobic core of the lipid membrane but entirely through the aqueous and hydrophilic environment to achieve a cross-membrane translocation. This mechanism sheds light on the intensive and fundamental debate on how a hydrophilic and charged peptide domain diffuses across the biologically inaccessible high-energy barrier of the hydrophobic core of a lipid bilayer: The peptide domain does not need to cross the hydrophobic core to move across a

  4. Polarized electromagnetic response of the moon

    NASA Technical Reports Server (NTRS)

    Sonett, C. P.; Smith, B. F.; Colburn, D. S.; Schubert, G.; Schwartz, K.

    1974-01-01

    The strong anisotropy in Apollo 15 Lunar Surface Magnetometer (LSM) signals resulting from electromagnetic induction in the moon, forced by fluctuations of the interplanetary magnetic field, is shown to result from intense polarization of the induced field. Arguments are given to show that the anisotropy cannot be explained wholly by asymmetric lunar induction in the presence of the diamagnetic cavity, but must be related to a regional influence. The weaker Apollo 12 anisotropy may also be associated with a regional influence. The site of Apollo 15 LSM at the edge of the Imbrium Basin suggests a preliminary model for calculations based on the possibility that Imbrium and perhaps Serenitatis are sources of the regional effect. Lastly, since the very low frequency induction seems free of the anisotropy, our earlier estimate of deep conductivity remains unchanged.

  5. Market applications of Resistivity, Induced Polarisation, Magnetic Resonance and Electromagnetic methods for Groundwater Investigations, Mining Exploration, Environmental and Engineering Surveys

    NASA Astrophysics Data System (ADS)

    Bernard, J.

    2012-12-01

    The Manufacturers of geophysical instruments have been facing these past decades the fast evolution of the electronics and of the computer sciences. More automatisms have been introduced into the equipment and into the processing and interpretation software which may let believe that conducting geophysical surveys requires less understanding of the method and less experience than in the past. Hence some misunderstandings in the skills that are needed to make the geophysical results well integrated among the global information which the applied geologist needs to acquire to be successful in his applications. Globally, the demand in geophysical investigation goes towards more penetration depth, requiring more powerful transmitters, and towards a better resolution, requiring more data such as in 3D analysis. Budgets aspects strongly suggest a high efficiency in the field associated to high speed data processing. The innovation is required in all aspects of geophysics to fit with the market needs, including new technological (instruments, software) and methodological (methods, procedures, arrays) developments. The structures in charge of the geophysical work can be public organisations (institutes, ministries, geological surveys,…) or can come from the private sector (large companies, sub-contractors, consultants, …), each one of them getting their own constraints in the field work and in the processing and interpretation phases. In the applications concerning Groundwater investigations, Mining Exploration, Environmental and Engineering surveys, examples of data and their interpretation presently carried out all around the world will be presented for DC Resistivity (Vertical Electrical Sounding, 2D, 3D Resistivity Imaging, Resistivity Monitoring), Induced Polarisation (Time Domain 2D, 3D arrays for mining and environmental), Magnetic Resonance Sounding (direct detection and characterisation of groundwater) and Electromagnetic (multi-component and multi

  6. Impact of environmentally induced fluctuations on quantum mechanically mixed electronic and vibrational pigment states in photosynthetic energy transfer and 2D electronic spectra

    SciTech Connect

    Fujihashi, Yuta; Ishizaki, Akihito; Fleming, Graham R.

    2015-06-07

    Recently, nuclear vibrational contribution signatures in two-dimensional (2D) electronic spectroscopy have attracted considerable interest, in particular as regards interpretation of the oscillatory transients observed in light-harvesting complexes. These transients have dephasing times that persist for much longer than theoretically predicted electronic coherence lifetime. As a plausible explanation for this long-lived spectral beating in 2D electronic spectra, quantum-mechanically mixed electronic and vibrational states (vibronic excitons) were proposed by Christensson et al. [J. Phys. Chem. B 116, 7449 (2012)] and have since been explored. In this work, we address a dimer which produces little beating of electronic origin in the absence of vibronic contributions, and examine the impact of protein-induced fluctuations upon electronic-vibrational quantum mixtures by calculating the electronic energy transfer dynamics and 2D electronic spectra in a numerically accurate manner. It is found that, at cryogenic temperatures, the electronic-vibrational quantum mixtures are rather robust, even under the influence of the fluctuations and despite the small Huang-Rhys factors of the Franck-Condon active vibrational modes. This results in long-lasting beating behavior of vibrational origin in the 2D electronic spectra. At physiological temperatures, however, the fluctuations eradicate the mixing, and hence, the beating in the 2D spectra disappears. Further, it is demonstrated that such electronic-vibrational quantum mixtures do not necessarily play a significant role in electronic energy transfer dynamics, despite contributing to the enhancement of long-lived quantum beating in 2D electronic spectra, contrary to speculations in recent publications.

  7. Cholesterol favors the emergence of a long-range autocorrelated fluctuation pattern in voltage-induced ionic currents through lipid bilayers.

    PubMed

    Corvalán, Natalia A; Kembro, Jackelyn M; Clop, Pedro D; Perillo, María A

    2013-08-01

    The present paper was aimed at evaluating the effect of cholesterol (CHO) on the voltage-induced lipid pore formation in bilayer membranes through a global characterization of the temporal dynamics of the fluctuation pattern of ion currents. The bilayer model used was black lipid membranes (BLMs) of palmitoyloleoylphosphatidylethanolamine and palmitoyloleoylphosphatidylcholine (POPE:POPC) at a 7:3 molar ratio in the absence (BLM0) or in the presence of 30 (BLM30), 40 (BLM40) or 50(BLM50)mol% of cholesterol with respect to total phospholipids. Electrical current intensities (I) were measured in voltage (ΔV) clamped conditions at ΔV ranging between 0 and ±200mV. The autocorrelation parameter α derived from detrended fluctuation analysis (DFA) on temporal fluctuation patterns of electrical currents allowed discriminating between non-correlated (α=0.5, white noise) and long-range correlated (0.5<α<1) behaviors. The increase in |ΔV| as well as in cholesterol content increased the number of conductance states, the magnitude of conductance level, the capacitance of the bilayers and increased the tendency towards the development of long-range autocorrelated (fractal) processes (0.5<α<1) in lipid channel generation. Experiments were performed above the phase transition temperature of the lipid mixtures, but compositions used predicted a superlattice-like organization. This leads to the conclusion that structural defects other than phase coexistence may promote lipid channel formation under voltage clamped conditions. Furthermore, cholesterol controls the voltage threshold that allows the percolation of channel behavior where isolated channels become an interconnected network.

  8. Expectations induced by natural-like temporal fluctuations are independent of attention decrement: evidence from behavior and early visual evoked potentials.

    PubMed

    Derosiere, Gerard; Farrugia, Nicolas; Perrey, Stéphane; Ward, Tomas; Torre, Kjerstin

    2015-01-01

    Temporal expectations and attention decrement affect human behavior in opposing ways: the former positively, the latter negatively yet both exhibit similar neural signatures - i.e., reduction in the early event-related potential components' amplitude - despite different underlying mechanisms. Furthermore, there is a significant and growing debate in the literature regarding the putative role of attention in the encoding of expectations in perception. The question then arises as to what are the behavioral and neural consequences, if any, of attention decrement on temporal expectations and related enhancement of sensory information processing. Here, we investigated behavioral performance and visual N1a, N1p and P1 components during a sustained attention reaction time task inducing attention decrement under two conditions. In one condition, the inter-stimulus intervals (ISIs) were randomly distributed to impede expectation effects while for the other, the ISI exhibited natural-like long-term correlations supposed to induce temporal expectations. Behavioral results show that natural-like fluctuations in ISI indeed induced faster RT due to temporal expectations. These temporal expectations were beneficial even under attention decrement circumstances. Further, temporal expectations were associated with reduced N1a amplitude while attention decrement was associated with reduced N1p amplitude. Our findings provide evidence that the effects of temporal expectations and attention decrement induced in a single task can be independent at the behavioral level, and are supported at separate information processing stages at the neural level in vision. PMID:25224996

  9. Electromagnetic fasteners

    DOEpatents

    Crane, Randolph W.; Marts, Donna J.

    1994-11-01

    An electromagnetic fastener for manipulating objects in space uses the matic attraction of various metals. An end effector is attached to a robotic manipulating system having an electromagnet such that when current is supplied to the electromagnet, the object is drawn and affixed to the end effector, and when the current is withheld, the object is released. The object to be manipulated includes a multiplicity of ferromagnetic patches at various locations to provide multiple areas for the effector on the manipulator to become affixed to the object. The ferromagnetic patches are sized relative to the object's geometry and mass.

  10. Electromagnetic fasteners

    DOEpatents

    Crane, Randolph W.; Marts, Donna J.

    1994-01-01

    An electromagnetic fastener for manipulating objects in space uses the matic attraction of various metals. An end effector is attached to a robotic manipulating system having an electromagnet such that when current is supplied to the electromagnet, the object is drawn and affixed to the end effector, and when the current is withheld, the object is released. The object to be manipulated includes a multiplicity of ferromagnetic patches at various locations to provide multiple areas for the effector on the manipulator to become affixed to the object. The ferromagnetic patches are sized relative to the object's geometry and mass.

  11. Frequency fluctuations in silicon nanoresonators

    PubMed Central

    Sansa, Marc; Sage, Eric; Bullard, Elizabeth C.; Gély, Marc; Alava, Thomas; Colinet, Eric; Naik, Akshay K.; Villanueva, Luis Guillermo; Duraffourg, Laurent; Roukes, Michael L.; Jourdan, Guillaume; Hentz, Sébastien

    2016-01-01

    Frequency stability is key to performance of nanoresonators. This stability is thought to reach a limit with the resonator’s ability to resolve thermally-induced vibrations. Although measurements and predictions of resonator stability usually disregard fluctuations in the mechanical frequency response, these fluctuations have recently attracted considerable theoretical interest. However, their existence is very difficult to demonstrate experimentally. Here, through a literature review, we show that all studies of frequency stability report values several orders of magnitude larger than the limit imposed by thermomechanical noise. We studied a monocrystalline silicon nanoresonator at room temperature, and found a similar discrepancy. We propose a new method to show this was due to the presence of frequency fluctuations, of unexpected level. The fluctuations were not due to the instrumentation system, or to any other of the known sources investigated. These results challenge our current understanding of frequency fluctuations and call for a change in practices. PMID:26925826

  12. Frequency fluctuations in silicon nanoresonators

    NASA Astrophysics Data System (ADS)

    Sansa, Marc; Sage, Eric; Bullard, Elizabeth C.; Gély, Marc; Alava, Thomas; Colinet, Eric; Naik, Akshay K.; Villanueva, Luis Guillermo; Duraffourg, Laurent; Roukes, Michael L.; Jourdan, Guillaume; Hentz, Sébastien

    2016-06-01

    Frequency stability is key to the performance of nanoresonators. This stability is thought to reach a limit with the resonator's ability to resolve thermally induced vibrations. Although measurements and predictions of resonator stability usually disregard fluctuations in the mechanical frequency response, these fluctuations have recently attracted considerable theoretical interest. However, their existence is very difficult to demonstrate experimentally. Here, through a literature review, we show that all studies of frequency stability report values several orders of magnitude larger than the limit imposed by thermomechanical noise. We studied a monocrystalline silicon nanoresonator at room temperature and found a similar discrepancy. We propose a new method to show that this was due to the presence of frequency fluctuations, of unexpected level. The fluctuations were not due to the instrumentation system, or to any other of the known sources investigated. These results challenge our current understanding of frequency fluctuations and call for a change in practices.

  13. Superfluid helium sloshing dynamics induced oscillations and fluctuations of angular momentum, force and moment actuated on spacecraft driven by gravity gradient or jitter acceleration associated with slew motion

    NASA Technical Reports Server (NTRS)

    Hung, R. J.

    1994-01-01

    The generalized mathematical formulation of sloshing dynamics for partially filled liquid of cryogenic superfluid helium II in dewar containers driven by the gravity gradient and jitter accelerations associated with slew motion for the purpose to perform scientific observation during the normal spacecraft operation are investigated. An example is given with the Advanced X-Ray Astrophysics Facility-Spectroscopy (AXAF-S) for slew motion which is responsible for the sloshing dynamics. The jitter accelerations include slew motion, spinning motion, atmospheric drag on the spacecraft, spacecraft attitude motions arising from machinery vibrations, thruster firing, pointing control of spacecraft, crew motion, etc. Explicit mathematical expressions to cover these forces acting on the spacecraft fluid systems are derived. The numerical computation of sloshing dynamics is based on the non-inertia frame spacecraft bound coordinate, and solve time-dependent, three-dimensional formulations of partial differential equations subject to initial and boundary conditions. The explicit mathematical expressions of boundary conditions to cover capillary force effect on the liquid-vapor interface in microgravity environments are also derived. The formulations of fluid moment and angular moment fluctuations in fluid profiles induced by the sloshing dynamics, together with fluid stress and moment fluctuations exerted on the spacecraft dewar containers have also been derived. Examples are also given for cases applicable to the AXAF-S spacecraft sloshing dynamics associated with slew motion.

  14. Analysis of liquid sodium purity by laser-induced breakdown spectroscopy. Modeling and correction of signal fluctuation prior to quantitation of trace elements

    NASA Astrophysics Data System (ADS)

    Maury, Cécile; Sirven, Jean-Baptiste; Tabarant, Michel; L'Hermite, Daniel; Courouau, Jean-Louis; Gallou, Catherine; Caron, Nadège; Moutiers, Gilles; Cabuil, Valérie

    2013-04-01

    Liquid sodium is used as coolant in sodium-cooled fast nuclear reactors. Among many parameters to monitor to ensure the safe operation of the reactor, the coolant chemical purity is a relevant indicator of several undesirable situations, like corrosion of structural materials or sodium contamination, which may release different elements in the coolant. Several techniques have already been implemented to measure the sodium purity, but their response time is long and not suited for continuous monitoring. Therefore, as a complement to them, laser-induced breakdown spectroscopy (LIBS) is considered as a promising technique for real-time analysis of the coolant purity. In this paper we report on the first LIBS quantitative measurements performed in liquid sodium at 150 °C. Calibration curves were traced for lead and indium using the standard addition method. Important intensity drifts and fluctuations were observed, mostly due to pressure variations in the sodium oven. Background subtraction and/or normalization was used to compensate for those intensity fluctuations. To describe the effect of these corrections on the analytical signal noise, a simple model was proposed and its results were found to satisfactorily fit the experimental data. Using this approach, the best detection limits were obtained for the background-subtracted and normalized data, and were found to be 6 ppm for lead and 5 ppm for indium.

  15. Identification of LAMBDA-like systems in Er{sup 3+}:Y{sub 2}SiO{sub 5} and observation of electromagnetically induced transparency

    SciTech Connect

    Baldit, E.; Bencheikh, K.; Monnier, P.; Briaudeau, S.; Levenson, J. A.; Crozatier, V.; Lorgere, I.; Bretenaker, F.; Le Goueet, J. L.; Guillot-Noeel, O.; Goldner, Ph.

    2010-04-01

    Electromagnetically induced transparency (EIT) is reported in a solid-state material doped with erbium ions. In this paper we introduce the spectroscopic investigations we have conducted in order to identify the adequate LAMBDA-like three-level systems in Er{sup 3+}:Y{sub 2}SiO{sub 5} crystal, relevant for the demonstration of EIT. These results pave the way for nonlinear and quantum optics applications based on EIT at the telecom wavelength around 1.5 mum.

  16. Effect of electromagnetic radiation modulated by biostructures on the course of alloxan-induced diabetes mellitus in rats.

    PubMed

    Garyaev, P P; Kokaya, A A; Mukhina, I V; Leonova-Garyaeva, E A; Kokaya, N G

    2007-02-01

    Exposure of rats with experimental diabetes mellitus to wide-band electromagnetic radiation generated by He-Ne laser and modulated by the pancreas and spleen is informing and phenomenological method prolonging animal life span, normalizing blood glucose level, and promoting regeneration of the pancreas.

  17. Evolution of magnetic fluctuations through the Fe-induced paramagnetic to ferromagnetic transition in Cr2B

    NASA Astrophysics Data System (ADS)

    Arčon, D.; Schoop, L. M.; Cava, R. J.; Felser, C.

    2016-03-01

    In itinerant ferromagnets, the quenched disorder is predicted to dramatically affect the ferromagnetic to paramagnetic quantum phase transition driven by external control parameters at zero temperature. Here we report a study on Fe-doped Cr2B , which, starting from the paramagnetic parent, orders ferromagnetically for Fe-doping concentrations x larger than xc=2.5 % . In parent Cr2B , 11B nuclear magnetic resonance data reveal the presence of both ferromagnetic and antiferromagnetic fluctuations. The latter are suppressed with Fe doping, before the ferromagnetic ones finally prevail for x >xc . Indications for non-Fermi-liquid behavior, usually associated with the proximity of a quantum critical point, were found for all samples, including undoped Cr2B . The sharpness of the ferromagneticlike transition changes on moving away from xc, indicating significant changes in the nature of the magnetic transitions in the vicinity of the quantum critical point. Our data provide some constraints for understanding quantum phase transitions in itinerant ferromagnets in the limit of weak quenched disorder.

  18. Density-of-states Fluctuation-induced Negative Out-of-plane Magnetoresistance in Overdoped Bi-2212

    NASA Astrophysics Data System (ADS)

    Usui, Tomohiro; Adachi, Shintaro; Watanabe, Takao; Nishizaki, Terukazu

    We analyzed the in-plane and out -of-plane m agnetoresistance (MR) f or o verdoped B i1.6Pb0.4Sr2CaCu2O8+δ (Bi-2212) s ingle crystals us ing s uperconductive f luctuation t heory, which considers the d ensity-of-states (DOS) contribution i n l ayered superconductors with the conventional s-wave pairing state. The out-of-plane results are well reproduced by the theory, implying that the large, negative out-of-plane MR as well as the sharp increase in the zero-field out-of-plane resistivityρc near the superconducting transition temperature Tc originate from the superconductive DOS fluctuation effect. On the other hand, the in-plane results are better reproduced without the D OS c ontribution (i.e., using only th e Aslamazov-Larkin (AL) contribution), which may be e xplained in terms of the d-wave superconductivity of the layered superconductors.

  19. Rapid fluctuations in extracellular brain glucose levels induced by natural arousing stimuli and intravenous cocaine: fueling the brain during neural activation

    PubMed Central

    Lenoir, Magalie

    2012-01-01

    Glucose, a primary energetic substrate for neural activity, is continuously influenced by two opposing forces that tend to either decrease its extracellular levels due to enhanced utilization in neural cells or increase its levels due to entry from peripheral circulation via enhanced cerebral blood flow. How this balance is maintained under physiological conditions and changed during neural activation remains unclear. To clarify this issue, enzyme-based glucose sensors coupled with high-speed amperometry were used in freely moving rats to evaluate fluctuations in extracellular glucose levels induced by brief audio stimulus, tail pinch (TP), social interaction with another rat (SI), and intravenous cocaine (1 mg/kg). Measurements were performed in nucleus accumbens (NAcc) and substantia nigra pars reticulata (SNr), which drastically differ in neuronal activity. In NAcc, where most cells are powerfully excited after salient stimulation, glucose levels rapidly (latency 2–6 s) increased (30–70 μM or 6–14% over baseline) by all stimuli; the increase differed in magnitude and duration for each stimulus. In SNr, where most cells are transiently inhibited by salient stimuli, TP, SI, and cocaine induced a biphasic glucose response, with the initial decrease (−20–40 μM or 5–10% below baseline) followed by a reboundlike increase. The critical role of neuronal activity in mediating the initial glucose response was confirmed by monitoring glucose currents after local microinjections of glutamate (GLU) or procaine (PRO). While intra-NAcc injection of GLU transiently increased glucose levels in this structure, intra-SNr PRO injection resulted in rapid, transient decreases in SNr glucose. Therefore, extracellular glucose levels in the brain change very rapidly after physiological and pharmacological stimulation, the response is structure specific, and the pattern of neuronal activity appears to be a critical factor determining direction and magnitude of physiological

  20. [Electromagnetic fields hypersensitivity].

    PubMed

    Sobiczewska, Elzbieta; Szmigielski, Stanisław

    2009-01-01

    The development of industry, particularly of new technologies in communication systems, gives rise to the number and diversty of electromagnetic field (EMF) sources in the environment. These sources, including power-frequent, radiofrequent and microwaves, make human life richer, safer and easier. But at the same time, there is growing concern about possible health risks connected with EMF exposure. An increasing number of persons have recently reported on a variety of health problems induced, in their opinion, by exposure to EMF. It is important to note that EMF levels to which these individuals are exposed are generally well below the recommended exposure limits and are certainly far below those known to produce any adverse effects. These persons call themselves "electromagnetic hypersensitivity individuals" And complain about experiencing various types of non-specific symptoms, including dermatological, neurological and vegetative. In the present paper, the problem of electromagnetic hypersensitivity phenomenon is discussed based on the recently published literature.

  1. Differential equations governing slip-induced pore-pressure fluctuations in a water-saturated granular medium

    USGS Publications Warehouse

    Iverson, R.M.

    1993-01-01

    Macroscopic frictional slip in water-saturated granular media occurs commonly during landsliding, surface faulting, and intense bedload transport. A mathematical model of dynamic pore-pressure fluctuations that accompany and influence such sliding is derived here by both inductive and deductive methods. The inductive derivation shows how the governing differential equations represent the physics of the steadily sliding array of cylindrical fiberglass rods investigated experimentally by Iverson and LaHusen (1989). The deductive derivation shows how the same equations result from a novel application of Biot's (1956) dynamic mixture theory to macroscopic deformation. The model consists of two linear differential equations and five initial and boundary conditions that govern solid displacements and pore-water pressures. Solid displacements and water pressures are strongly coupled, in part through a boundary condition that ensures mass conservation during irreversible pore deformation that occurs along the bumpy slip surface. Feedback between this deformation and the pore-pressure field may yield complex system responses. The dual derivations of the model help explicate key assumptions. For example, the model requires that the dimensionless parameter B, defined here through normalization of Biot's equations, is much larger than one. This indicates that solid-fluid coupling forces are dominated by viscous rather than inertial effects. A tabulation of physical and kinematic variables for the rod-array experiments of Iverson and LaHusen and for various geologic phenomena shows that the model assumptions commonly are satisfied. A subsequent paper will describe model tests against experimental data. ?? 1993 International Association for Mathematical Geology.

  2. Experimental system for real-time assessment of potential changes in protein conformation induced by electromagnetic fields.

    PubMed

    Beyer, Christian; Christen, Philipp; Jelesarov, Ilian; Fröhlich, Jürg

    2013-09-01

    A novel experimental system to distinguish between potential thermal and non-thermal effects of electromagnetic fields (EMFs) on the conformational equilibrium and folding kinetics of proteins is presented. The system comprises an exposure chamber installed within the measurement compartment of a spectropolarimeter and allows real-time observation of the circular dichroism (CD) signal of the protein during EMF exposure. An optical temperature probe monitors the temperature of the protein solution at the site of irradiation. The electromagnetic, thermal, and fluid-dynamic behavior of the system is characterized by numerical and experimental means. The number of repeated EMF on/off cycles needed for achieving a certain detection limit is determined on the basis of the experimentally assessed precision of the CD measurements. The isolated thermosensor protein GrpE of the Hsp70 chaperone system of Eschericha coli serves as the test protein. Long-term experiments show high thermal reproducibility as well as thermal stability of the experimental setup.

  3. Electromagnetically induced generation, gain in delayed wave mixing, and measuring coherent states using quantum-interference windows

    NASA Astrophysics Data System (ADS)

    Pop, I.; Moorman, L.

    1999-07-01

    A three-level atom interacting with classical electromagnetic fields is coherently excited by a two-photon transition near resonance and subsequently makes a second transition driven at resonance by a weak ir field at the noise level. Our calculation predicts generation of an electromagnetic field at a third frequency in the uv from zero field. Calculations show a gain of the uv radiation with propagation through the medium, though the populations of the two levels involved are never inverted. Other calculations produce a pulsed amplifier, two-photon optical nutation, and free induction memory. An effective susceptibility is defined and its imaginary part is found to be a good indicator of mode specific absorption and emission by the atomic state, and its real part a good indicator of dispersion. These calculations exemplify the possibility of coherent control over an atomic vapor and the production of a superradient macroscopic ensemble of states in the retarded frame for realistic parameters.

  4. Experimental Demonstration of the Effectiveness of Electromagnetically Induced Transparency for Enhancing Cross-Phase Modulation in the Short-Pulse Regime

    NASA Astrophysics Data System (ADS)

    Dmochowski, Greg; Feizpour, Amir; Hallaji, Matin; Zhuang, Chao; Hayat, Alex; Steinberg, Aephraim M.

    2016-04-01

    We present an experiment using a sample of laser-cooled Rb atoms to show that cross-phase modulation schemes continue to benefit from electromagnetically induced transparency (EIT) even as the transparency window is made narrower than the signal bandwidth (i.e., for signal pulses much shorter than the response time of the EIT system). Addressing concerns that narrow EIT windows might not prove useful for such applications, we show that while the peak phase shift saturates in this regime, it does not drop, and the time-integrated effect continues to scale inversely with EIT window width. This integrated phase shift is an important figure of merit for tasks such as the detection of single-photon-induced cross-phase shifts. Only when the window width approaches the system's dephasing rate γ does the peak phase shift begin to decrease, leading to an integrated phase shift that peaks when the window width is equal to 4 γ .

  5. Dynamical control of soliton formation and propagation in a Y-type atomic system with dual ladder-type electromagnetically induced transparency

    NASA Astrophysics Data System (ADS)

    Si, Liu-Gang; Lü, Xin-You; Hao, Xiangying; Li, Jia-Hua

    2010-03-01

    We have investigated the nonlinear interaction between a weak-pulsed probe field and a four-level Y-type atomic system with dual ladder-type electromagnetically induced transparency. Two strong coupling fields induce a quantum destructive interference effect which depletes the population in the two nearly degenerate uppermost levels of the system and dramatically enhances the linear as well as nonlinear dispersion while simultaneously significantly suppressing the probe field absorption. We present the semiclassical quantum analysis of the system. The perturbation method of multiple scales is used to derive a differential envelope equation that describes the propagation of the probe field in the Y-type atomic system. It is then demonstrated that bright and dark optical solitons can be formed in this system.

  6. Dissociable effects of antipsychotics on ketamine-induced changes in regional oxygenation and inter-regional coherence of low frequency oxygen fluctuations in the rat.

    PubMed

    Li, Jennifer; Ishiwari, Keita; Conway, Michael W; Francois, Jennifer; Huxter, John; Lowry, John P; Schwarz, Adam J; Tricklebank, Mark; Gilmour, Gary

    2014-06-01

    Typical and atypical antipsychotics have been shown to alleviate N-methyl-D-aspartate (NMDA) receptor antagonist-induced BOLD signals in healthy humans and animals to differing degrees; factors that might relate to their different molecular mechanisms and clinical profiles. Recent studies have also extended these investigations to the analysis of resting state functional connectivity measures of BOLD signals in different brain regions. Using constant potential amperometry, we examined the effects of the NMDA receptor antagonist S-(+)-ketamine on tissue oxygen levels in medial prefrontal cortex (mPFC) and medial ventral striatum (mVS), and temporal coherence of low-frequency oxygen fluctuations between these regions in freely moving rats. Furthermore, we assessed the extent to which the atypical antipsychotic clozapine and the typical antipsychotic haloperidol could modulate the effects of S-(+)-ketamine on these measures. Acute S-(+)-ketamine (5-25 mg/kg) produced dose-dependent increases in both tissue O2 levels and coherence. Although effects of clozapine and haloperidol alone were relatively minor, their effects on ketamine-induced signals were markedly more distinct. Clozapine dose-dependently attenuated the absolute S-(+)-ketamine (25 mg/kg) O2 signal in both regions, and also attenuated ketamine-induced increases in regional coherence. Haloperidol had no effect on the absolute ketamine O2 signal yet potentiated increases in regional coherence. The dissociable effects of haloperidol and clozapine on ketamine-induced hyperoxygenation and mPFC-mVS coherence elucidate potentially important mechanistic differences between these classes of pharmacology. This study demonstrates for the first time that in vivo amperometry can measure both regional brain tissue O2 levels and inter-regional coherence, advancing BOLD-like measurements of functional connectivity into awake, unconstrained animals.

  7. On zero frequency magnetic fluctuations in plasmas

    SciTech Connect

    Tajima, T.; Cable, S. . Inst. for Fusion Studies); Kulsrud, R.M. . Dept. of Astrophysical Sciences)

    1992-01-01

    A plasma sustains fluctuations of electromagnetic fields and particle density even in a thermal equilibrium and such fluctuations have a large zero frequency peak. The level of fluctuations in the plasma for a given wavelength and frequency of electromagnetic fields is calculated through the fluctuation-dissipation theorem. The frequency spectrum shows that the energy contained in this peak is complementary to the energy lost'' by the plasma cutoff effect. The level of the zero (or nearly zero) frequency magnetic is computed as {l angle}B{sup 2}{r angle}{sup 0}/ 8{pi} = 1/2{pi}{sup 3}T({omega}{sub p}/c){sup 3}, where T and {omega}{sub p} are the temperature and plasma frequency. The relation between the nonradiative and radiative fluctuations is elucidated. Both a simple collision model and a kinetic theoretic treatment are presented with essentially the same results. The size of the fluctuations is {lambda} {approximately} (c/{omega}{sub p})({eta}/{omega}){sup {1/2}}, where {eta} and {omega} are the collision frequency and the (nearly zero) frequency of magnetic fields oscillations. Perhaps the most dramatic application of the present theory, however, is to the cosmological plasma of early epoch. Implications of these magnetic fields in the early Universe are discussed. Quantum mechanical calculations are also carried out for degenerate plasmas.

  8. On zero frequency magnetic fluctuations in plasmas

    SciTech Connect

    Tajima, T.; Cable, S.; Kulsrud, R.M.

    1992-01-01

    A plasma sustains fluctuations of electromagnetic fields and particle density even in a thermal equilibrium and such fluctuations have a large zero frequency peak. The level of fluctuations in the plasma for a given wavelength and frequency of electromagnetic fields is calculated through the fluctuation-dissipation theorem. The frequency spectrum shows that the energy contained in this peak is complementary to the energy ``lost`` by the plasma cutoff effect. The level of the zero (or nearly zero) frequency magnetic is computed as {l_angle}B{sup 2}{r_angle}{sup 0}/ 8{pi} = 1/2{pi}{sup 3}T({omega}{sub p}/c){sup 3}, where T and {omega}{sub p} are the temperature and plasma frequency. The relation between the nonradiative and radiative fluctuations is elucidated. Both a simple collision model and a kinetic theoretic treatment are presented with essentially the same results. The size of the fluctuations is {lambda} {approximately} (c/{omega}{sub p})({eta}/{omega}){sup {1/2}}, where {eta} and {omega} are the collision frequency and the (nearly zero) frequency of magnetic fields oscillations. Perhaps the most dramatic application of the present theory, however, is to the cosmological plasma of early epoch. Implications of these magnetic fields in the early Universe are discussed. Quantum mechanical calculations are also carried out for degenerate plasmas.

  9. Can the Gulf Stream induce coherent short-term fluctuations in sea level along the US East Coast? A modeling study

    NASA Astrophysics Data System (ADS)

    Ezer, Tal

    2016-02-01

    Much attention has been given in recent years to observations and models that show that variations in the transport of the Atlantic Meridional Overturning Circulation (AMOC) and in the Gulf Stream (GS) can contribute to interannual, decadal, and multi-decadal variations in coastal sea level (CSL) along the US East Coast. However, less is known about the impact of short-term (time scales of days to weeks) fluctuations in the GS and their impact on CSL anomalies. Some observations suggest that these anomalies can cause unpredictable minor tidal flooding in low-lying areas when the GS suddenly weakens. Can these short-term CSL variations be attributed to changes in the transport of the GS? An idealized numerical model of the GS has been set up to test this proposition. The regional model uses a 1/12° grid with a simplified coastline to eliminate impacts from estuaries and small-scale coastal features and thus isolate the GS impact. The GS in the model is driven by inflows/outflows, representing the Florida Current (FC), the Slope Current (SC), and the Sargasso Sea (SS) flows. Forcing the model with an oscillatory FC transport with a period of 2, 5, and 10 days produced coherent CSL variations from Florida to the Gulf of Maine with similar periods. However, when imposing variations in the transports of the SC or the SS, they induce CSL variations only north of Cape Hatteras. The suggested mechanism is that variations in GS transport produce variations in sea level gradient across the entire GS length and this large-scale signal is then transmitted into the shelf by the generation of coastal-trapped waves (CTW). In this idealized model, the CSL variations induced by variations of ˜10 Sv in the transport of the GS are found to resemble CSL variations induced by ˜5 m s-1 zonal wind fluctuations, though the mechanisms of wind-driven and GS-driven sea level are quite different. Better understanding of the relation between variations in offshore currents and CSL will help

  10. Understanding the influence of solvent field and fluctuations on the stability of photo-induced charge-separated state in molecular triad

    NASA Astrophysics Data System (ADS)

    Balamurugan, D.; Aquino, Adelia; Lischka, Hans; Dios, Francis; Flores, Lionel; Cheung, Margaret

    2013-03-01

    Molecular triad composed of fullerene, porphyrin, and carotene is an artificial analogue of natural photosynthetic system and is considered for applications in solar energy conversion because of its ability to produce long-lived photo-induced charge separated state. The goal of the present multiscale simulation is to understand how the stability of photo-induced charge-separated state in molecular triad is influenced by a polar organic solvent, namely tetrahydrofuran (THF). The multiscale approach is based on combined quantum, classical molecular dynamics, and statistical physics calculations. The quantum chemical calculations were performed on the triad using the second order algebraic diagrammatic perturbation and time-dependent density functional theory. Molecular dynamics simulations were performed on triad in a box of THF solvent with the replica exchange method. The two methods on different length and time scales are bridged through an important sampling technique. We have analyzed the free energy landscape, structural fluctuations, and the long- range electrostatic interactions between triad and solvent molecules. The results suggest that the polarity and re-organization of the solvent is critical in stabilization of charge-separated state in triad. Supported by DOE (DE-FG02-10ER16175)

  11. On the mechanism of seismo-electromagnetic phenomena and their possible role in the electromagnetic radiation during periods of earthquakes, foreshocks and aftershocks

    NASA Astrophysics Data System (ADS)

    Khatiashvili, N. G.; Perel'man, M. E.

    1989-10-01

    We describe generation of low- and radio-frequency electromagnetic radiation (EMR) by seismic waves of pressure applied to a neutral nonpiezoelectrical medium. The EMR is induced during the process of ionic crystal fracture and formation of a mosaic of fluctuation charges on the opposite sides of the cracks, the formation and oscillation of charged dislocations and the vibrations of very small conducting or magnetized particles in dielectrics with fluctuating charges proportional to their radius and temperature. The most interesting source of EMR emission is the process of formation and oscillation of double electric layers (DEL). The DEL can be modelled as a system of capacitors or electric dipoles. The variation of their parameters by external pressure, by changes of water content, etc., leads directly to the EMR emission. As DELs are widespread in rocks, they can make an essential contribution to the EMR. DEL oscillation induced by tectonic processes is probably the main contribution.

  12. Long-term electromagnetic pulse exposure induces Abeta deposition and cognitive dysfunction through oxidative stress and overexpression of APP and BACE1.

    PubMed

    Jiang, Da-Peng; Li, Jin-Hui; Zhang, Jie; Xu, Sheng-Long; Kuang, Fang; Lang, Hai-Yang; Wang, Ya-Feng; An, Guang-Zhou; Li, Jing; Guo, Guo-Zhen

    2016-07-01

    A progressively expanded literature has been devoted in the past years to the noxious or beneficial effects of electromagnetic field (EMF) to Alzheimer׳s disease (AD). This study concerns the relationship between electromagnetic pulse (EMP) exposure and the occurrence of AD in rats and the underlying mechanisms, focusing on the role of oxidative stress (OS). 55 healthy male Sprague Dawley (SD) rats were used and received continuous exposure for 8 months. Morris water maze (MWM) test was conducted to test the ability of cognitive and memory. The level of OS was detected by superoxide dismutase (SOD) activity and glutathione (GSH) content. We found that long-term EMP exposure induced cognitive damage in rats. The content of β-amyloid (Aβ) protein in hippocampus was increased after long-term EMP exposure. OS of hippocampal neuron was detected. Western blotting and immunohistochemistry (IHC) assay showed that the content of Aβ protein and its oligomers in EMP-exposed rats were higher than that of sham-exposed rats. The content of Beta Site App Cleaving Enzyme (BACE1) and microtubule-associated protein 1 light chain 3-II (LC3-II) in EMP-exposed rats hippocampus were also higher than that of sham-exposed rats. SOD activity and GSH content in EMP-exposed rats were lower than sham-exposed rats (p<0.05). Several mechanisms were proposed based on EMP exposure-induced OS, including increased amyloid precursor protein (APP) aberrant cleavage. Although further study is needed, the present results suggest that long-term EMP exposure is harmful to cognitive ability in rats and could induce AD-like pathological manifestation. PMID:26972535

  13. Long-term electromagnetic pulse exposure induces Abeta deposition and cognitive dysfunction through oxidative stress and overexpression of APP and BACE1.

    PubMed

    Jiang, Da-Peng; Li, Jin-Hui; Zhang, Jie; Xu, Sheng-Long; Kuang, Fang; Lang, Hai-Yang; Wang, Ya-Feng; An, Guang-Zhou; Li, Jing; Guo, Guo-Zhen

    2016-07-01

    A progressively expanded literature has been devoted in the past years to the noxious or beneficial effects of electromagnetic field (EMF) to Alzheimer׳s disease (AD). This study concerns the relationship between electromagnetic pulse (EMP) exposure and the occurrence of AD in rats and the underlying mechanisms, focusing on the role of oxidative stress (OS). 55 healthy male Sprague Dawley (SD) rats were used and received continuous exposure for 8 months. Morris water maze (MWM) test was conducted to test the ability of cognitive and memory. The level of OS was detected by superoxide dismutase (SOD) activity and glutathione (GSH) content. We found that long-term EMP exposure induced cognitive damage in rats. The content of β-amyloid (Aβ) protein in hippocampus was increased after long-term EMP exposure. OS of hippocampal neuron was detected. Western blotting and immunohistochemistry (IHC) assay showed that the content of Aβ protein and its oligomers in EMP-exposed rats were higher than that of sham-exposed rats. The content of Beta Site App Cleaving Enzyme (BACE1) and microtubule-associated protein 1 light chain 3-II (LC3-II) in EMP-exposed rats hippocampus were also higher than that of sham-exposed rats. SOD activity and GSH content in EMP-exposed rats were lower than sham-exposed rats (p<0.05). Several mechanisms were proposed based on EMP exposure-induced OS, including increased amyloid precursor protein (APP) aberrant cleavage. Although further study is needed, the present results suggest that long-term EMP exposure is harmful to cognitive ability in rats and could induce AD-like pathological manifestation.

  14. DIRECT CURRENT ELECTROMAGNETIC PUMP

    DOEpatents

    Barnes, A.H.

    1957-11-01

    An improved d-c electromagnetic pump is presented in which the poles, and consequently the magetic gap at the poles, are tapered to be wider at the upstream end. In addition, the cross section of the tube carryiQ the liquid metal is tapered so that the velocity of the pumped liquid increases in the downstream direction at a rate such that the counter-induced voltage in the liquid metal remains constant as it traverses the region between the poles. This configuration compensates for the distortion of the magnetic field caused by the induced voltage that would otherwise result in the lowering of the pumping capacity. This improved electromagnetic pump as practical application in the pumping of liquid metal coolants for nuclear reactors where conventional positive displacement pumps have proved unsatisfactory due to the high temperatures and the corrosive properties of the liquid metals involved.

  15. Orientation-induced enhancement in electromagnetic properties of ZnFe2O4/SiO2/PANI core/shell/shell nanostructured disks

    NASA Astrophysics Data System (ADS)

    Wang, Jiaheng; Or, Siu Wing

    2016-05-01

    ZnFe2O4/SiO2/PANI (ZSP) core/shell/shell nanostructured disks are prepared and fabricated into paraffin-bonded ZSP composite rings with random, vertical, and horizontal orientations of the easy magnetization planes of the ZSP disks in the paraffin binder in order to study the effect of directional orientation of the easy magnetization planes on their electromagnetic properties. The easy magnetization planes induced by shape anisotropy and oriented by a magnetic field in the vertically oriented ring result in a general enhancement in permeability of 7-60% in the broad UHF-Ku (0.1-18 GHz) bands, while those in the horizontally oriented ring lead to a significant enhancement of 58-1100% in the low-frequency L and S (1-4 GHz) bands, in comparison with the randomly oriented ring. The observed permeability agrees with the theoretical prediction based on the Landau-Lifshitz-Gilbert equation and the Bruggeman's effective medium theory. The horizontal and vertical arrangements of dipolar polarizations in the vertically and horizontally oriented rings give rise to 3-11% enhancement and weakening in permittivity, respectively, compared to the randomly oriented ring. The enhancement in permeability also improves and broadens the electromagnetic wave absorption in both vertically and horizontally oriented rings, especially in the L and S bands for the horizontally oriented ring.

  16. Heat Shock–Induced Fluctuations in Clock and Light Signaling Enhance Phytochrome B–Mediated Arabidopsis Deetiolation[C][W

    PubMed Central

    Karayekov, Elizabeth; Sellaro, Romina; Legris, Martina; Yanovsky, Marcelo J.; Casal, Jorge J.

    2013-01-01

    Moderately warm constant ambient temperatures tend to oppose light signals in the control of plant architecture. By contrast, here we show that brief heat shocks enhance the inhibition of hypocotyl growth induced by light perceived by phytochrome B in deetiolating Arabidopsis thaliana seedlings. In darkness, daily heat shocks transiently increased the expression of PSEUDO-RESPONSE REGULATOR7 (PRR7) and PRR9 and markedly enhanced the amplitude of the rhythms of LATE ELONGATED HYPOCOTYL (LHY) and CIRCADIAN CLOCK ASSOCIATED1 (CCA1) expression. In turn, these rhythms gated the hypocotyl response to red light, in part by changing the expression of PHYTOCHROME INTERACTING FACTOR4 (PIF4) and PIF5. After light exposure, heat shocks also reduced the nuclear abundance of CONSTITUTIVE PHOTOMORPHOGENIC1 (COP1) and increased the abundance of its target ELONGATED HYPOCOTYL5 (HY5). The synergism between light and heat shocks was deficient in the prr7 prr9, lhy cca1, pif4 pif5, cop1, and hy5 mutants. The evening element (binding site of LHY and CCA1) and G-box promoter motifs (binding site of PIFs and HY5) were overrepresented among genes with expression controlled by both heat shock and red light. The heat shocks experienced by buried seedlings approaching the surface of the soil prepare the seedlings for the impending exposure to light by rhythmically lowering LHY, CCA1, PIF4, and PIF5 expression and by enhancing HY5 stability. PMID:23933882

  17. Damage effect and mechanism of the GaAs pseudomorphic high electron mobility transistor induced by the electromagnetic pulse

    NASA Astrophysics Data System (ADS)

    Xiao-Wen, Xi; Chang-Chun, Chai; Gang, Zhao; Yin-Tang, Yang; Xin-Hai, Yu; Yang, Liu

    2016-04-01

    The damage effect and mechanism of the electromagnetic pulse (EMP) on the GaAs pseudomorphic high electron mobility transistor (PHEMT) are investigated in this paper. By using the device simulation software, the distributions and variations of the electric field, the current density and the temperature are analyzed. The simulation results show that there are three physical effects, i.e., the forward-biased effect of the gate Schottky junction, the avalanche breakdown, and the thermal breakdown of the barrier layer, which influence the device current in the damage process. It is found that the damage position of the device changes with the amplitude of the step voltage pulse. The damage appears under the gate near the drain when the amplitude of the pulse is low, and it also occurs under the gate near the source when the amplitude is sufficiently high, which is consistent with the experimental results. Project supported by the National Basic Research Program of China (Grant No. 2014CB339900), and the Open Fund of Key Laboratory of Complex Electromagnetic Environment Science and Technology, China Academy of Engineering Physics (CAEP) (Grant No. 2015-0214.XY.K).

  18. Remote-controlled eradication of astrogliosis in spinal cord injury via electromagnetically-induced dexamethasone release from "smart" nanowires.

    PubMed

    Gao, Wen; Borgens, Richard Ben

    2015-08-10

    We describe a system to deliver drugs to selected tissues continuously, if required, for weeks. Drugs can be released remotely inside the small animals using pre-implanted, novel vertically aligned electromagnetically-sensitive polypyrrole nanowires (PpyNWs). Approximately 1-2mm(2) dexamethasone (DEX) doped PpyNWs was lifted on a single drop of sterile water by surface tension, and deposited onto a spinal cord lesion in glial fibrillary acidic protein-luc transgenic mice (GFAP-luc mice). Overexpression of GFAP is an indicator of astrogliosis/neuroinflammation in CNS injury. The corticosteroid DEX, a powerful ameliorator of inflammation, was released from the polymer by external application of an electromagnetic field for 2h/day for a week. The GFAP signal, revealed by bioluminescent imaging in the living animal, was significantly reduced in treated animals. At 1week, GFAP was at the edge of detection, and in some experimental animals, completely eradicated. We conclude that the administration of drugs can be controlled locally and non-invasively, opening the door to many other known therapies, such as the cases that dexamethasone cannot be safely applied systemically in large concentrations. PMID:25979326

  19. Societal Impacts of Solar Electromagnetic Radiation

    NASA Astrophysics Data System (ADS)

    Lean, J. L.

    2000-05-01

    Changes in solar electromagnetic radiation, which occur continuously and at all wavelengths of the spectrum, can have significant societal impacts on a wide range of time scales. Detection of climate change and ozone depletion requires reliable specification of solar-induced processes that mask or exacerbate anthropogenic effects. Living with, and mitigating, climate change and ozone depletion has significant economic, habitat and political impacts of international extent. As an example, taxes to restrict carbon emission may cause undue economic stress if the role of greenhouse gases in global warming is incorrectly diagnosed. Ignoring solar-induced ozone changes in the next century may lead to incorrect assessment of the success of the Montreal Protocol in protecting the ozone layer by limiting the use of ozone-destroying chlorofluorocarbons. Societal infrastructure depends in many ways on space-based technological assets. Communications and navigation for commerce, industry, science and defense rely on satellite signals transmitted through, and reflected by, electrons in the ionosphere. Electron densities change in response to solar flares, and by orders of magnitude in response to EUV and X-ray flux variations during the Sun's 11-year activity cycle. Spacecraft and space debris experience enhanced drag on their orbits when changing EUV radiation causes upper atmosphere densities to increase. Especially affected are spacecraft and debris in lower altitude orbits, such as Iridium-type communication satellites, and the International Space Station (ISS). Proper specification of solar-induced fluctuations in the neutral upper atmosphere can, for example, aid in tracking the ISS and surrounding space debris, reducing the chance of ISS damage from collisions, and maximizing its operations. Aspects of solar electromagnetic radiation variability will be briefly illustrated on a range of time scales, with specific identification of the societal impacts of different

  20. Synthetic gelatinases inhibitor attenuates electromagnetic pulse-induced blood-brain barrier disruption by inhibiting gelatinases-mediated ZO-1 degradation in rats.

    PubMed

    Qiu, Lian-Bo; Zhou, Yan; Wang, Qi; Yang, Long-Long; Liu, Hai-Qiang; Xu, Sheng-Long; Qi, Yu-Hong; Ding, Gui-Rong; Guo, Guo-Zhen

    2011-07-11

    Previously we found that exposure to electromagnetic pulse (EMP) induced an increase in blood-brain-barrier (BBB) permeability and the degradation of tight junction protein ZO-1 in rats. Matrix metalloproteinases (MMPs), in particular gelatinases (MMP-2 and MMP-9), play a key role in degradation of tight junction proteins, are known mediators of BBB compromise. We hypothesized that the degradation of ZO-1 by gelatinases contributed to EMP-induced BBB opening. To test this hypothesis, the mRNA level of ZO-1, protein levels of MMP-2, MMP-9 and tissue inhibitor of metalloproteinases (TIMP-1 and TIMP-2) were detected in rat cerebral cortex after exposing rats to EMP at 200 kV/m for 200 pulses. It was found that the mRNA level of ZO-1 was unaltered at different time points after EMP exposure. The protein levels of MMP-2 and MMP-9 significantly increased at 3 h and 0.5 h, respectively. However, TIMP-1 (inhibitor of MMP-9) and TIMP-2 (inhibitor of MMP-2) only moderately increased after EMP exposure. In addition, in situ zymography results showed that the gelatinase activity increased in cerebral microvessels at 3 h after EMP exposure. When rats were treated with gelatinases inhibitor (SB-3CT) before EMP exposure, the EMP-induced BBB opening was attenuated and the ZO-1 degradation was reversed. Our results suggested that EMP-induced BBB opening was related to gelatinase mediated ZO-1 degradation.