WorldWideScience

Sample records for strong polarization dependence

  1. Efficient three-photon luminescence with strong polarization dependence from a scintillating silicate glass co-doped with Gd3+ and Tb3+.

    Science.gov (United States)

    Li, Guang-Can; Zhang, Cheng-Yun; Deng, Hai-Dong; Liu, Guang-Yin; Lan, Sheng; Qian, Qi-; Yang, Zhong-Min; Gopal, Achanta Venu

    2013-03-11

    Efficient three-photon luminescence (3PL) from a scintillating silicate glass co-doped with Gd(3+) and Tb(3+) was generated by using a focused femtosecond laser beam at 800 nm. Four emission bands centered at 496, 541, 583, and 620 nm were identified as the electronic transitions between the energy levels of Tb(3+) followed by three-photon absorption (3PA) in Gd(3+) and Tb(3+) and the resonant energy transfer from Gd(3+) to Tb(3+). More interestingly, a strong polarization dependence of the 3PL was observed and it is ascribed to the polarization dependent 3PA in Gd(3+) and Tb(3+) and/or the angular distribution of photogenerated electrons in the glass.

  2. Frequency dependent polarization in blazars

    International Nuclear Information System (INIS)

    Bjoernsson, C.I.

    1984-10-01

    It is argued that the intrinsic frequency dependent polarization in blazars finds its most straightforward explanations in terms of a single rather than a multicomponent sourcemodel. In order to reproduce the observations, under the assumption that the emission mechanism is optically thin synchrotron radiation, both a well ordered magnetic field and an electron distribution with a sharp break or cuttoff are necessary. Non-uniform pitch angle distribution and/or environments where synchrotron losses are important are both conducive to producing strong frequency dependent polarization. Reasons are put forth as to why such conditions ar expected to occur in blazars. Two specific models are discussed in detail and it is shown that they are both able to produce strong frequency dependent polarization, even when the spectral index changes by a small amount only. (orig.)

  3. Polarization-dependent aluminum metasurface operating at 450 nm

    DEFF Research Database (Denmark)

    Højlund-Nielsen, Emil; Zhu, Xiaolong; Carstensen, Marcus S

    2015-01-01

    We report on a polarization-dependent plasmonic aluminum-based high-density metasurface operating at blue wavelengths. The fabricated sub-wavelength structures, tailored in size and geometry, possess strong, localized, plasmonic resonances able to control linear polarization. Best performance...

  4. ACCELERATION OF POLARIZED BEAMS USING MULTIPLE STRONG PARTIAL SIBERIAN SNAKES

    International Nuclear Information System (INIS)

    ROSER, T.; AHRENS, L.; BAI, M.

    2004-01-01

    Acceleration of polarized protons in the energy range of 5 to 25 GeV is particularly difficult since depolarizing spin resonances are strong enough to cause significant depolarization but full Siberian snakes cause intolerably large orbit excursions. Using a 20-30% partial Siberian snake both imperfection and intrinsic resonances can be overcome. Such a strong partial Siberian snake was designed for the Brookhaven AGS using a dual pitch helical superconducting dipole. Multiple strong partial snakes are also discussed for spin matching at beam injection and extraction

  5. Algorithms and Programs for Strong Gravitational Lensing In Kerr Space-time Including Polarization

    Science.gov (United States)

    Chen, Bin; Kantowski, Ronald; Dai, Xinyu; Baron, Eddie; Maddumage, Prasad

    2015-05-01

    Active galactic nuclei (AGNs) and quasars are important astrophysical objects to understand. Recently, microlensing observations have constrained the size of the quasar X-ray emission region to be of the order of 10 gravitational radii of the central supermassive black hole. For distances within a few gravitational radii, light paths are strongly bent by the strong gravity field of the central black hole. If the central black hole has nonzero angular momentum (spin), then a photon’s polarization plane will be rotated by the gravitational Faraday effect. The observed X-ray flux and polarization will then be influenced significantly by the strong gravity field near the source. Consequently, linear gravitational lensing theory is inadequate for such extreme circumstances. We present simple algorithms computing the strong lensing effects of Kerr black holes, including the effects on polarization. Our algorithms are realized in a program “KERTAP” in two versions: MATLAB and Python. The key ingredients of KERTAP are a graphic user interface, a backward ray-tracing algorithm, a polarization propagator dealing with gravitational Faraday rotation, and algorithms computing observables such as flux magnification and polarization angles. Our algorithms can be easily realized in other programming languages such as FORTRAN, C, and C++. The MATLAB version of KERTAP is parallelized using the MATLAB Parallel Computing Toolbox and the Distributed Computing Server. The Python code was sped up using Cython and supports full implementation of MPI using the “mpi4py” package. As an example, we investigate the inclination angle dependence of the observed polarization and the strong lensing magnification of AGN X-ray emission. We conclude that it is possible to perform complex numerical-relativity related computations using interpreted languages such as MATLAB and Python.

  6. ALGORITHMS AND PROGRAMS FOR STRONG GRAVITATIONAL LENSING IN KERR SPACE-TIME INCLUDING POLARIZATION

    International Nuclear Information System (INIS)

    Chen, Bin; Maddumage, Prasad; Kantowski, Ronald; Dai, Xinyu; Baron, Eddie

    2015-01-01

    Active galactic nuclei (AGNs) and quasars are important astrophysical objects to understand. Recently, microlensing observations have constrained the size of the quasar X-ray emission region to be of the order of 10 gravitational radii of the central supermassive black hole. For distances within a few gravitational radii, light paths are strongly bent by the strong gravity field of the central black hole. If the central black hole has nonzero angular momentum (spin), then a photon’s polarization plane will be rotated by the gravitational Faraday effect. The observed X-ray flux and polarization will then be influenced significantly by the strong gravity field near the source. Consequently, linear gravitational lensing theory is inadequate for such extreme circumstances. We present simple algorithms computing the strong lensing effects of Kerr black holes, including the effects on polarization. Our algorithms are realized in a program “KERTAP” in two versions: MATLAB and Python. The key ingredients of KERTAP are a graphic user interface, a backward ray-tracing algorithm, a polarization propagator dealing with gravitational Faraday rotation, and algorithms computing observables such as flux magnification and polarization angles. Our algorithms can be easily realized in other programming languages such as FORTRAN, C, and C++. The MATLAB version of KERTAP is parallelized using the MATLAB Parallel Computing Toolbox and the Distributed Computing Server. The Python code was sped up using Cython and supports full implementation of MPI using the “mpi4py” package. As an example, we investigate the inclination angle dependence of the observed polarization and the strong lensing magnification of AGN X-ray emission. We conclude that it is possible to perform complex numerical-relativity related computations using interpreted languages such as MATLAB and Python

  7. Plasmonic vortex generator without polarization dependence

    Science.gov (United States)

    Wang, Han; Liu, Lixia; Liu, Chunxiang; Li, Xing; Wang, Shuyun; Xu, Qing; Teng, Shuyun

    2018-03-01

    In view of the limitations of vortex generators with polarization dependence at present, we propose a plasmonic vortex generator composed of rectangular holes etched in silver film, in which the optical vortex can be generated under arbitrary linearly polarized light illumination. Two sets of rectangular holes are arranged equidistantly on a circle and rotate in postulate directions. Theoretical analysis provides the design principle for the vortex generator, and numerical simulations give guidance on designating the vortex generator parameters. Experimental measurements verify the performance of the proposed vortex generator. Moreover, two alternative structures for the generation of a plasmonic vortex are also provided in this paper. The resulting perfect vortex, compact structure and flexible illumination conditions will lead to wide applications of this plasmonic vortex generator.

  8. Jeans instability in collisional strongly coupled dusty plasma with radiative condensation and polarization force

    Energy Technology Data Exchange (ETDEWEB)

    Prajapati, R. P., E-mail: prajapati-iter@yahoo.co.in; Bhakta, S. [Department of Pure and Applied Physics, Guru Ghasidas Central University, Bilaspur-495009 (C.G.) (India); Chhajlani, R. K. [Retired from School of Studies in Physics, Vikram University, Ujjain-456010 (M.P.) (India)

    2016-05-15

    The influence of dust-neutral collisions, polarization force, and electron radiative condensation is analysed on the Jeans (gravitational) instability of partially ionized strongly coupled dusty plasma (SCDP) using linear perturbation (normal mode) analysis. The Boltzmann distributed ions, dynamics of inertialess electrons, charged dust and neutral particles are considered. Using the plane wave solutions, a general dispersion relation is derived which is modified due to the presence of dust-neutral collisions, strong coupling effect, polarization force, electron radiative condensation, and Jeans dust/neutral frequencies. In the long wavelength perturbations, the Jeans instability criterion depends upon strong coupling effect, polarization interaction parameter, and thermal loss, but it is independent of dust-neutral collision frequency. The stability of the considered configuration is analysed using the Routh–Hurwitz criterion. The growth rates of Jeans instability are illustrated, and stabilizing influence of viscoelasticity and dust-neutral collision frequency while destabilizing effect of electron radiative condensation, polarization force, and Jeans dust-neutral frequency ratio is observed. This work is applied to understand the gravitational collapse of SCDP with dust-neutral collisions.

  9. Hole dynamics and spin currents after ionization in strong circularly polarized laser fields

    International Nuclear Information System (INIS)

    Barth, Ingo; Smirnova, Olga

    2014-01-01

    We apply the time-dependent analytical R-matrix theory to develop a movie of hole motion in a Kr atom upon ionization by strong circularly polarized field. We find rich hole dynamics, ranging from rotation to swinging motion. The motion of the hole depends on the final energy and the spin of the photoelectron and can be controlled by the laser frequency and intensity. Crucially, hole rotation is a purely non-adiabatic effect, completely missing in the framework of quasistatic (adiabatic) tunneling theories. We explore the possibility to use hole rotation as a clock for measuring ionization time. Analyzing the relationship between the relative phases in different ionization channels we show that in the case of short-range electron-core interaction the hole is always initially aligned along the instantaneous direction of the laser field, signifying zero delays in ionization. Finally, we show that strong-field ionization in circular fields creates spin currents (i.e. different flow of spin-up and spin-down density in space) in the ions. This phenomenon is intimately related to the production of spin-polarized electrons in strong laser fields Barth and Smirnova (2013 Phys. Rev. A 88 013401). We demonstrate that rich spin dynamics of electrons and holes produced during strong field ionization can occur in typical experimental conditions and does not require relativistic intensities or strong magnetic fields. (paper)

  10. Effect of dipole polarizability on positron binding by strongly polar molecules

    International Nuclear Information System (INIS)

    Gribakin, G F; Swann, A R

    2015-01-01

    A model for positron binding to polar molecules is considered by combining the dipole potential outside the molecule with a strongly repulsive core of a given radius. Using existing experimental data on binding energies leads to unphysically small core radii for all of the molecules studied. This suggests that electron–positron correlations neglected in the simple model play a large role in determining the binding energy. We account for these by including the polarization potential via perturbation theory and non-perturbatively. The perturbative model makes reliable predictions of binding energies for a range of polar organic molecules and hydrogen cyanide. The model also agrees with the linear dependence of the binding energies on the polarizability inferred from the experimental data (Danielson et al 2009 J. Phys. B: At. Mol. Opt. Phys. 42 235203). The effective core radii, however, remain unphysically small for most molecules. Treating molecular polarization non-perturbatively leads to physically meaningful core radii for all of the molecules studied and enables even more accurate predictions of binding energies to be made for nearly all of the molecules considered. (paper)

  11. Polarization and collision velocity dependence of associative ionization in cold Na (3p)-Na(3p) collisions

    NARCIS (Netherlands)

    Meijer, H.A.J.

    1990-01-01

    We studied the polarization dependence of the associative ionization (AI) process Na(3p) + Na(3p) → Na2+ at collision velocities between 100 and 700 m/s (5 and 200 K), using linearly and circularly polarized light for the excitation. We found that the polarization dependence varies strongly in the

  12. The Impact of Strong Cathodic Polarization on SOC Electrolyte Materials

    DEFF Research Database (Denmark)

    Kreka, Kosova; Hansen, Karin Vels; Jacobsen, Torben

    2016-01-01

    current density. In case of a cell voltage above 1.6 V, p-type and n-type electronic conductivity are often observed at the anode and cathode respectively3. Hence, a considerable part of the current is lost as leakage through the electrolyte, thus lowering the efficiency of the cell considerably....... of impurities at the grain boundaries, electrode poisoning, delamination or cracks of the electrolyte etc., have been observed in cells operated at such conditions, lowering the lifetime of the cell1,2. High polarizations are observed at the electrolyte/cathode interface of an electrolysis cell operated at high...

  13. Annular billiard dynamics in a circularly polarized strong laser field

    Science.gov (United States)

    Kamor, A.; Mauger, F.; Chandre, C.; Uzer, T.

    2012-01-01

    We analyze the dynamics of a valence electron of the buckminsterfullerene molecule (C60) subjected to a circularly polarized laser field by modeling it with the motion of a classical particle in an annular billiard. We show that the phase space of the billiard model gives rise to three distinct trajectories: “whispering gallery orbits,” which hit only the outer billiard wall; “daisy orbits,” which hit both billiard walls (while rotating solely clockwise or counterclockwise for all time); and orbits that only visit the downfield part of the billiard, as measured relative to the laser term. These trajectories, in general, maintain their distinct features, even as the intensity is increased from 1010 to 1014Wcm-2. We attribute this robust separation of phase space to the existence of twistless tori.

  14. Polarization-Dependent Multi-Functional Metamaterial as Polarization Filter, Transparent Wall and Circular Polarizer using Ring-Cross Resonator

    Directory of Open Access Journals (Sweden)

    Z. Zhang

    2017-09-01

    Full Text Available We propose a polarization-dependent multi-functional metamaterial using ring-cross resonator. Based on the analysis of surface current distributions induced by different polarized incidence, we demonstrate that the proposed metamaterial serves as a polarization filter, a transparent wall and a circular polarizer under different polarization normal incidence. Additionally, parameter analyses on the control of resonance are discussed to complementally explain the physical origin. Simulated results show that the proposed metamaterial functions as a polarization filter eliminating the x-polarization wave at 10.1 GHz and y-polarization wave at 14.3 GHz, a transparent wall transmitting both x-polarized and y-polarized incident waves at 12.6 GHz, and a broadband circular polarizer converting the +45° polarized (-45° polarized incident wave to the left (right handed circularly polarized wave from 10.8 to 12.8 GHz, respectively. Measured results agree well with the simulation and validate the performance of the proposed multifunctional metamaterial.

  15. Pretransitional behaviour in the vicinity of the isotropic-nematic transition of strongly polar compounds

    International Nuclear Information System (INIS)

    Sridevi, S; Krishna Prasad, S; Shankar Rao, D S; Yelamaggad, C V

    2008-01-01

    The isotropic-nematic transition, being weakly first order, exhibits pretransitional effects signifying the appearance of the nematic-like regions in the isotropic phase. In the isotropic phase, strongly polar liquid crystals, such as the popular alkyl and alkoxy cyano biphenyl behave in a non-standard fashion: whereas far away from the transition the dielectric constant ε iso has a 1/T dependence (a feature also commonly seen in polar liquids), on approaching the nematic phase the trend reverses resulting in a maximum in ε iso , at a temperature slightly above the transition, an effect explained on the basis of short-range correlations with an antiparallel association of the neighbouring molecules. Recently, there has been a revival in studies on this behaviour to possibly associate it with the order of transition. Here we report dielectric measurements carried in the vicinity of this transition for a number of compounds having different molecular structures including a bent core system, but with a common feature that the molecules possess a strong terminal polar group, nitro in one case and cyano in the rest. Surprisingly, the convex shape of the thermal variation of ε iso was more an exception than the rule. In materials that exhibit such an anomaly we find a linear correlation between δε = (ε peak -ε IN )/ε IN and δT = T peak -T IN , where ε peak is the maximum value of the dielectric constant in the isotropic phase, ε IN the value at the transition, and T peak and T IN the corresponding temperatures.

  16. Scale dependence and small x behaviour of polarized parton distributions

    CERN Document Server

    Ball, R D; Ridolfi, G; Forte, S; Ridolfi, G

    1995-01-01

    We discuss perturbative evolution of the polarized structure function g_1 in the (x,Q^2) plane, with special regard to the small-x region. We determine g_1 in terms of polarized quark and gluon distributions using coefficient functions to order alpha_s. At small x g_1 then displays substantial scale dependence, which necessarily implies a corresponding scale dependence in the large-x region. This scale dependence has significant consequences for the extraction of the first moment from the experimental data, reducing its value while increasing the error. Conversely, the scale dependence may be used to constrain the size of the polarized gluon distribution.

  17. Strong-field ionization of polar molecules: Stark-shift-corrected strong-field approximation

    DEFF Research Database (Denmark)

    Dimitrovski, Darko; Martiny, Christian P. J.; Madsen, Lars Bojer

    2010-01-01

    We extend the molecular strong-field approximation for ionization, in the tunneling limit, to include systematically the linear and quadratic static Stark shifts of the ionizing molecular orbital. This approach, simple to implement, is capable of describing the essential physics of the process of...

  18. Polarization and Strong Infra-Red Activity in Compressed Solid Hydrogen

    OpenAIRE

    Souza, Ivo; Martin, Richard M.

    1998-01-01

    Under a pressure of ~150 GPa solid molecular hydrogen undergoes a phase transition accompanied by a dramatic rise in infra-red absorption in the vibron frequency range. We use the Berry's phase approach to calculate the electric polarization in several candidate structures finding large, anisotropic dynamic charges and strongly IR-active vibron modes. The polarization is shown to be greatly affected by the overlap between the molecules in the crystal, so that the commonly used Clausius-Mossot...

  19. The wavelength dependence of polarization in NGC 2023

    International Nuclear Information System (INIS)

    Rolph, C. D.; Scarrott, S. M.

    1989-01-01

    NGC 2023 is a bright reflection nebula illuminated by the central star HD37903. At 2 microns the nebula is seen solely by reflected light from the central star but in the NIR there is excess radiation that is supposed to arise from thermal emission from a population of small grains (Sellgren, 1984). The unexpectedly high surface brightness at R and I wavelengths has led to the suggestion that even at these wavelengths there is a significant contribution from this thermal emission process (Witt, Schild, and Kraiman, 1984). If the nebula is seen by reflected starlight then this radiation will be linearly polarized. The level of polarization depends on the scattering geometry, grain size distribution, etc., and is typically 20 to 40 percent for nebulae such as NGC 1999 which is morphologically similar to NGC 2023. If, in any waveband, there is a contribution of radiation from emission processes this radiation will be unpolarized and will serve to dilute the scattered radiation to give a lower level of observed polarization. A study of the wavelength dependence of polarization in nebulae in which there may be thermal emission from grains will indicate the contribution from this process to the total luminosity. Polarization maps were produced in BVRI wavebands for the NGC 2023 nebulosity which confirm that at all wavelengths it is a reflection nebula illuminated by a central star. The wavelength dependence of polarization at representative points in the nebula and in a scatter plot of polarization in V and I wavebands at all points at which measurements are given. Results indicate that throughout the nebula there is a general trend for the level of polarization to increase with wavelength and that maximum levels of polarization occur at the longest wavelengths. No evidence is seen in the data for any significant contribution from the thermal emission from grains in the BVRI luminosity of NGC 2023

  20. Strong dependence of ultracold chemical rates on electric dipole moments

    International Nuclear Information System (INIS)

    Quemener, Goulven; Bohn, John L.

    2010-01-01

    We use the quantum threshold laws combined with a classical capture model to provide an analytical estimate of the chemical quenching cross sections and rate coefficients of two colliding particles at ultralow temperatures. We apply this quantum threshold model (QT model) to indistinguishable fermionic polar molecules in an electric field. At ultracold temperatures and in weak electric fields, the cross sections and rate coefficients depend only weakly on the electric dipole moment d induced by the electric field. In stronger electric fields, the quenching processes scale as d 4(L+(1/2)) where L>0 is the orbital angular-momentum quantum number between the two colliding particles. For p-wave collisions (L=1) of indistinguishable fermionic polar molecules at ultracold temperatures, the quenching rate thus scales as d 6 . We also apply this model to pure two-dimensional collisions and find that chemical rates vanish as d -4 for ultracold indistinguishable fermions. This model provides a quick and intuitive way to estimate chemical rate coefficients of reactions occuring with high probability.

  1. Angle-dependent rotation of calcite in elliptically polarized light

    Science.gov (United States)

    Herne, Catherine M.; Cartwright, Natalie A.; Cattani, Matthew T.; Tracy, Lucas A.

    2017-08-01

    Calcite crystals trapped in an elliptically polarized laser field exhibit intriguing rotational motion. In this paper, we show measurements of the angle-dependent motion, and discuss how the motion of birefringent calcite can be used to develop a reliable and efficient process for determining the polarization ellipticity and orientation of a laser mode. The crystals experience torque in two ways: from the transfer of spin angular momentum (SAM) from the circular polarization component of the light, and from a torque due to the linear polarization component of the light that acts to align the optic axis of the crystal with the polarization axis of the light. These torques alternatingly compete with and amplify each other, creating an oscillating rotational crystal velocity. We model the behavior as a rigid body in an angle-dependent torque. We experimentally demonstrate the dependence of the rotational velocity on the angular orientation of the crystal by placing the crystals in a sample solution in our trapping region, and observing their behavior under different polarization modes. Measurements are made by acquiring information simultaneously from a quadrant photodiode collecting the driving light after it passes through the sample region, and by imaging the crystal motion onto a camera. We finish by illustrating how to use this model to predict the ellipticity of a laser mode from rotational motion of birefringent crystals.

  2. Off-specular polarized neutron reflectometry study of magnetic dots with a strong shape anisotropy

    CERN Document Server

    Temst, K; Moshchalkov, V V; Bruynseraede, Y; Fritzsche, H; Jonckheere, R

    2002-01-01

    We have measured the off-specular polarized neutron reflectivity of a regular array of rectangular magnetic polycrystalline Co dots, which were prepared by a combination of electron-beam lithography, molecular beam deposition, and lift-off processes. The dots have a length-to-width ratio of 4:1 imposing a strong shape anisotropy. The intensity of the off-specular satellite reflection was monitored as a function of the magnetic field applied parallel to the rows of dots and in the plane of the sample, allowing us to analyze the magnetization-reversal process using the four spin-polarized cross sections. (orig.)

  3. Polarization dependence of Na* + Na* associative ionization revisited

    NARCIS (Netherlands)

    Meijer, H.A.J.; Meulen, H.P. v.d.; Morgenstern, R.; Hertel, I.V.; Meyer, E.; Witte, R.

    1986-01-01

    The dependence of the associative ionization process Na 3 2P3/2 + Na 3 2P3/2 → Na2+ + e- on the polarization of the laser light used for Na excitation was independently investigated in Utrecht and Berlin. The purpose of this paper is to clarify discrepancies between two other earlier experimental

  4. Characterization of a magnetic trap by polarization dependent Zeeman spectroscopy

    DEFF Research Database (Denmark)

    Nielsen, Carsten Vandel; Lyngsøe, Jens Kristian; Thorseth, Anders

    2008-01-01

    This paper demonstrates a detailed experimental study of our cloverleaf magnetic trap for sodium atoms. By using polarization dependent Zeeman spectroscopy of our atomic beam, passing the magnetic trap region, we have determined important trap parameters such as gradients, their curvatures...

  5. Strong cosmic censorship for solutions of the Einstein-Maxwell field equations with polarized Gowdy symmetry

    Energy Technology Data Exchange (ETDEWEB)

    Nungesser, Ernesto; Rendall, Alan D [Max-Planck-Institut fuer Gravitationsphysik, Albert-Einstein-Institut, Am Muehlenberg 1, 14476 Potsdam (Germany)

    2009-05-21

    A proof of strong cosmic censorship is presented for a class of solutions of the Einstein-Maxwell equations, those with polarized Gowdy symmetry. A key element of the argument is the observation that by means of a suitable choice of variables the central equations in this problem can be written in a form where they are identical to the central equations for general (i.e. non-polarized) vacuum Gowdy spacetimes. Using this, it is seen that the deep results of Ringstroem on strong cosmic censorship in the vacuum case have implications for the Einstein-Maxwell case. Working out the geometrical meaning of these analytical results leads to the main conclusion.

  6. Effects of strong cathodic polarization of the Ni-YSZ interface

    DEFF Research Database (Denmark)

    Hansen, Karin Vels; Chen, Ming; Jacobsen, Torben

    2016-01-01

    Long-term strong cathodic polarization experiments of down to -2.4 V vs. E°(O2) of the Ni-YSZ interface were performed at 900°C in 97% H2/3% H2O on model electrodes. The Ni-YSZ interface underwent extensive changes and a large affected volume with a complex microstructure and phase distribution r...

  7. Periodic array of quantum rings strongly coupled to circularly polarized light as a topological insulator

    Science.gov (United States)

    Kozin, V. K.; Iorsh, I. V.; Kibis, O. V.; Shelykh, I. A.

    2018-01-01

    We demonstrate theoretically that a strong high-frequency circularly polarized electromagnetic field can turn a two-dimensional periodic array of interconnected quantum rings into a topological insulator. The elaborated approach is applicable to calculate and analyze the electron energy spectrum of the array, the energy spectrum of the edge states, and the corresponding electronic densities. As a result, the present theory paves the way to optical control of the topological phases in ring-based mesoscopic structures.

  8. Strong Linear Dichroism in Spin-Polarized Photoemission from Spin-Orbit-Coupled Surface States.

    Science.gov (United States)

    Bentmann, H; Maaß, H; Krasovskii, E E; Peixoto, T R F; Seibel, C; Leandersson, M; Balasubramanian, T; Reinert, F

    2017-09-08

    A comprehensive understanding of spin-polarized photoemission is crucial for accessing the electronic structure of spin-orbit coupled materials. Yet, the impact of the final state in the photoemission process on the photoelectron spin has been difficult to assess in these systems. We present experiments for the spin-orbit split states in a Bi-Ag surface alloy showing that the alteration of the final state with energy may cause a complete reversal of the photoelectron spin polarization. We explain the effect on the basis of ab initio one-step photoemission theory and describe how it originates from linear dichroism in the angular distribution of photoelectrons. Our analysis shows that the modulated photoelectron spin polarization reflects the intrinsic spin density of the surface state being sampled differently depending on the final state, and it indicates linear dichroism as a natural probe of spin-orbit coupling at surfaces.

  9. Polarization dependent switching of asymmetric nanorings with a circular field

    Directory of Open Access Journals (Sweden)

    Nihar R. Pradhan

    2016-01-01

    Full Text Available We experimentally investigated the switching from onion to vortex states in asymmetric cobalt nanorings by an applied circular field. An in-plane field is applied along the symmetric or asymmetric axis of the ring to establish domain walls (DWs with symmetric or asymmetric polarization. A circular field is then applied to switch from the onion state to the vortex state, moving the DWs in the process. The asymmetry of the ring leads to different switching fields depending on the location of the DWs and direction of applied field. For polarization along the asymmetric axis, the field required to move the DWs to the narrow side of the ring is smaller than the field required to move the DWs to the larger side of the ring. For polarization along the symmetric axis, establishing one DW in the narrow side and one on the wide side, the field required to switch to the vortex state is an intermediate value.

  10. Constraints on cosmological birefringence energy dependence from CMB polarization data

    International Nuclear Information System (INIS)

    Gubitosi, G.; Paci, F.

    2013-01-01

    We study the possibility of constraining the energy dependence of cosmological birefringence by using CMB polarization data. We consider four possible behaviors, characteristic of different theoretical scenarios: energy-independent birefringence motivated by Chern-Simons interactions of the electromagnetic field, linear energy dependence motivated by a 'Weyl' interaction of the electromagnetic field, quadratic energy dependence, motivated by quantum gravity modifications of low-energy electrodynamics, and inverse quadratic dependence, motivated by Faraday rotation generated by primordial magnetic fields. We constrain the parameters associated to each kind of dependence and use our results to give constraints on the models mentioned. We forecast the sensitivity that Planck data will be able to achieve in this respect

  11. Angle-dependent strong-field molecular ionization rates with tuned range-separated time-dependent density functional theory.

    Science.gov (United States)

    Sissay, Adonay; Abanador, Paul; Mauger, François; Gaarde, Mette; Schafer, Kenneth J; Lopata, Kenneth

    2016-09-07

    Strong-field ionization and the resulting electronic dynamics are important for a range of processes such as high harmonic generation, photodamage, charge resonance enhanced ionization, and ionization-triggered charge migration. Modeling ionization dynamics in molecular systems from first-principles can be challenging due to the large spatial extent of the wavefunction which stresses the accuracy of basis sets, and the intense fields which require non-perturbative time-dependent electronic structure methods. In this paper, we develop a time-dependent density functional theory approach which uses a Gaussian-type orbital (GTO) basis set to capture strong-field ionization rates and dynamics in atoms and small molecules. This involves propagating the electronic density matrix in time with a time-dependent laser potential and a spatial non-Hermitian complex absorbing potential which is projected onto an atom-centered basis set to remove ionized charge from the simulation. For the density functional theory (DFT) functional we use a tuned range-separated functional LC-PBE*, which has the correct asymptotic 1/r form of the potential and a reduced delocalization error compared to traditional DFT functionals. Ionization rates are computed for hydrogen, molecular nitrogen, and iodoacetylene under various field frequencies, intensities, and polarizations (angle-dependent ionization), and the results are shown to quantitatively agree with time-dependent Schrödinger equation and strong-field approximation calculations. This tuned DFT with GTO method opens the door to predictive all-electron time-dependent density functional theory simulations of ionization and ionization-triggered dynamics in molecular systems using tuned range-separated hybrid functionals.

  12. Polarization-dependent interfacial coupling modulation of ferroelectric photovoltaic effect in PZT-ZnO heterostructures

    Science.gov (United States)

    Pan, Dan-Feng; Bi, Gui-Feng; Chen, Guang-Yi; Zhang, Hao; Liu, Jun-Ming; Wang, Guang-Hou; Wan, Jian-Guo

    2016-03-01

    Recently, ferroelectric perovskite oxides have drawn much attention due to potential applications in the field of solar energy conversion. However, the power conversion efficiency of ferroelectric photovoltaic effect currently reported is far below the expectable value. One of the crucial problems lies in the two back-to-back Schottky barriers, which are formed at the ferroelectric-electrode interfaces and blocking most of photo-generated carriers to reach the outside circuit. Herein, we develop a new approach to enhance the ferroelectric photovoltaic effect by introducing the polarization-dependent interfacial coupling effect. Through inserting a semiconductor ZnO layer with spontaneous polarization into the ferroelectric ITO/PZT/Au film, a p-n junction with strong polarization-dependent interfacial coupling effect is formed. The power conversion efficiency of the heterostructure is improved by nearly two orders of magnitude and the polarization modulation ratio is increased about four times. It is demonstrated that the polarization-dependent interfacial coupling effect can give rise to a great change in band structure of the heterostructure, not only producing an aligned internal electric field but also tuning both depletion layer width and potential barrier height at PZT-ZnO interface. This work provides an efficient way in developing highly efficient ferroelectric-based solar cells and novel optoelectronic memory devices.

  13. Carbon nanotube growth on nanozirconia under strong cathodic polarization in steam and carbon dioxide

    DEFF Research Database (Denmark)

    Tao, Youkun; Ebbesen, Sune Dalgaard; Zhang, Wei

    2014-01-01

    Growth of carbon nanotubes (CNTs) catalyzed by zirconia nanoparticles was observed in the Ni-yttria doped zirconia (YSZ) composite cathode of a solid oxide electrolysis cell (SOEC) at approximately 875 °C during co-electrolysis of CO2 and H2O to produce CO and H 2. CNT was observed to grow under...... nanozirconia acting as a catalyst for the growth of carbon nanotubes (CNTs) during electrochemical conversion of carbon dioxide and water in a nickel-yttria- stabilized zirconia cermet under strong cathodic polarization. An electrocatalytic mechanism is proposed for the growth of the CNTs. ${{{\\rm {\\rm V...

  14. Graphene superlattices in strong circularly polarized fields: Chirality, Berry phase, and attosecond dynamics

    Science.gov (United States)

    Koochaki Kelardeh, Hamed; Apalkov, Vadym; Stockman, Mark I.

    2017-08-01

    We propose and theoretically explore states of graphene superlattices with relaxed P and T symmetries created by strong circularly polarized ultrashort pulses. The conduction-band electron distribution in the reciprocal space forms an interferogram with discontinuities related to topological (Berry) fluxes at the Dirac points. This can be studied using time- and angle-resolved photoemission spectroscopy (TR-ARPES). Our findings hold promise for control and observation of ultrafast electron dynamics in topological solids and may be applied to petahertz-scale information processing.

  15. Probing the ionization wave packet and recollision dynamics with an elliptically polarized strong laser field in the nondipole regime

    Science.gov (United States)

    Maurer, J.; Willenberg, B.; Daněk, J.; Mayer, B. W.; Phillips, C. R.; Gallmann, L.; Klaiber, M.; Hatsagortsyan, K. Z.; Keitel, C. H.; Keller, U.

    2018-01-01

    We explore ionization and rescattering in strong mid-infrared laser fields in the nondipole regime over the full range of polarization ellipticity. In three-dimensional photoelectron momentum distributions (3D PMDs) measured with velocity map imaging spectroscopy, we observe the appearance of a sharp ridge structure along the major polarization axis. Within a certain range of ellipticity, the electrons in this ridge are clearly separated from the two lobes that commonly appear in the PMD with elliptically polarized laser fields. In contrast to the well-known lobes of direct electrons, the sharp ridge is created by Coulomb focusing of the softly recolliding electrons. These ridge electrons are directly related to a counterintuitive shift of the PMD peak opposite to the laser beam propagation direction when the dipole approximation breaks down. The ellipticity-dependent 3D PMDs give access to different ionization and recollision dynamics with appropriate filters in the momentum space. For example, we can extract information about the spread of the initial wave packet and the Coulomb momentum transfer of the rescattering electrons.

  16. Anomalously strong relaxation of the polarization of muons in the magnetically ordered and paramagnetic states of the TbMnO3 multiferroic

    Science.gov (United States)

    Andrievskii, D. S.; Vorob'ev, S. I.; Getalov, A. L.; Golovenchits, E. I.; Komarov, E. N.; Kotov, S. A.; Sanina, V. A.; Shcherbakov, G. V.

    2017-09-01

    An anomalously strong relaxation of the muon polarization in a magnetically ordered state in the TbMnO3 multiferroic has been revealed by the method below the μ SR Néel temperature (42 K). Such a relaxation is due to the muon channel of relaxation of the polarization and the interaction of the magnetic moment of the muon with inhomogeneities of the internal magnetic field of an ordered state in the form of a cycloid. Above the Néel temperature, beginning with temperatures depending on the applied magnetic field, a two-phase state has been revealed where one phase has an anomalously strong relaxation of the muon polarization for a paramagnetic state. These features of the paramagnetic state are due to short-range magnetic order domains that appear in strongly frustrated TbMnO3. A true paramagnetic state has been observed only at T ≥ 150 K.

  17. Strong Circularly Polarized Luminescence from Highly Emissive Terbium Complexes in Aqueous Solution

    Energy Technology Data Exchange (ETDEWEB)

    Samuel, Amanda; Lunkley, Jamie; Muller, Gilles; Raymond, Kenneth

    2010-03-15

    Two luminescent terbium(III) complexes have been prepared from chiral ligands containing 2-hydroxyisophthalamide (IAM) antenna chromophores and their non-polarized and circularly-polarized luminescence properties have been studied. These tetradentate ligands, which form 2:1 ligand/Tb{sup III} complexes, utilize diaminocyclohexane (cyLI) and diphenylethylenediamine (dpenLI) backbones, which we reasoned would impart conformational rigidity and result in Tb{sup III} complexes that display both large luminescence quantum yield ({phi}) values and strong circularly polarized luminescence (CPL) activities. Both Tb{sup III} complexes are highly emissive, with {phi} values of 0.32 (dpenLI-Tb) and 0.60 (cyLI-Tb). Luminescence lifetime measurements in H{sub 2}O and D{sub 2}O indicate that while cyLI-Tb exists as a single species in solution, dpenLI-Tb exists as two species: a monohydrate complex with one H{sub 2}O molecule directly bound to the Tb{sup III} ion and a complex with no water molecules in the inner coordination sphere. Both cyLI-Tb and dpenLI-Tb display increased CPL activity compared to previously reported Tb{sup III} complexes made with chiral IAM ligands. The CPL measurements also provide additional confirmation of the presence of a single emissive species in solution in the case of cyLI-Tb, and multiple emissive species in the case of dpenLI-Tb.

  18. Imaging of Polarization-dependent Photocurrent in Graphene Photodevices

    Science.gov (United States)

    Kim, Minjung; Yoon, Duhee; Ang Yoon, Ho; Lee, Sang Wook; Cheong, Hyeonsik

    2012-02-01

    Recently, a metal-graphene-metal photodetector for high-speed optical communications was reported. In addition, a graphene-based photodetector was reported to be able to absorb broadband light owing to the unique band structure of graphene [Mueller et al., Nature Photonics 4, 297 (2010)]. We investigated the polarization dependence of the photocurrent generated in metal-graphene-metal junctions. The graphene photodevice was fabricated by depositing Pd/Au and Ti/Au electrodes on single-layer graphene samples. When the polarization of incident laser beam is rotated with respect to the metal-graphene-metal junction, the photocurrent is significantly modulated. In addition, we measured the exact positions where the photocurrent is generated by measuring the photocurrent and Raman images of the graphene photodevices simultaneously.

  19. Polarization-dependent responses of fluorescent indicators partitioned into myelinated axons

    Science.gov (United States)

    Micu, Ileana; Brideau, Craig; Stys, Peter K.

    2012-02-01

    Myelination, i.e. the wrapping of axons in multiple layers of lipid-rich membrane, is a unique phenomenon in the nervous systems of both vertebrates and invertebrates, that greatly increases the speed and efficiency of signal transmission. In turn, disruption of axo-myelinic integrity underlies disability in numerous clinical disorders. The dependence of myelin physiology on nanometric organization of its lamellae makes it difficult to accurately study this structure in the living state. We expected that fluorescent probes might become highly oriented when partitioned into the myelin sheath, and in turn, this anisotropy could be interrogated by controlling the polarization state of the exciting laser field used for 2-photon excited fluorescence (TPEF). Live ex vivo myelinated rodent axons were labeled with a series of lipohilic and hydrophilic fluorescenct probes, and TPEF images acquired while laser polarization was varied at the sample over a broad range of ellipticities and orientations of the major angle [see Brideau, Micu & Stys, abstract this meeting]. We found that most probes exhibited strong dependence on both the major angle of polarization, and perhaps more surprisingly, on ellipticity as well. Lipophilic vs. hydrophilic probes exhibited distinctly different behavior. We propose that polarization-dependent TPEF microscopy represents a powerful tool for probing the nanostructural architecture of both myelin and axonal cytoskeleton in a domain far below the resolution limit of visible light microscopy. By selecting probes with different sizes and physicochemical properties, distinct aspects of cellular nanoarchitecture can be accurately interrogated in real-time in living tissue.

  20. Comment on `The azimuthal dependence of surface wave polarization in a slightly anisotropic medium' by T. Tanimoto

    Science.gov (United States)

    Maupin, Valérie

    2004-10-01

    This comment points out that the simple azimuthal dependence of the polarization anomalies derived in a recent paper by Tanimoto may not be valid for the Love wave fundamental mode in oceanic or tectonic regions as a result of strong coupling with the first Rayleigh wave overtone. More generally, I also point out the fact that polarization anomalies reflect partly the anisotropy away from the station and that this usually complicates the azimuthal pattern observed at single stations.

  1. Temperature-Dependent Polarization in Field-Effect Transport and Photovoltaic Measurements of Methylammonium Lead Iodide.

    Science.gov (United States)

    Labram, John G; Fabini, Douglas H; Perry, Erin E; Lehner, Anna J; Wang, Hengbin; Glaudell, Anne M; Wu, Guang; Evans, Hayden; Buck, David; Cotta, Robert; Echegoyen, Luis; Wudl, Fred; Seshadri, Ram; Chabinyc, Michael L

    2015-09-17

    While recent improvements in the reported peak power conversion efficiency (PCE) of hybrid organic-inorganic perovskite solar cells have been truly astonishing, there are many fundamental questions about the electronic behavior of these materials. Here we have studied a set of electronic devices employing methylammonium lead iodide ((MA)PbI3) as the active material and conducted a series of temperature-dependent measurements. Field-effect transistor, capacitor, and photovoltaic cell measurements all reveal behavior consistent with substantial and strongly temperature-dependent polarization susceptibility in (MA)PbI3 at temporal and spatial scales that significantly impact functional behavior. The relative PCE of (MA)PbI3 photovoltaic cells is observed to reduce drastically with decreasing temperature, suggesting that such polarization effects could be a prerequisite for high-performance device operation.

  2. Polarization-gradient laser cooling as a way to create strongly localized structures for atom lithography

    International Nuclear Information System (INIS)

    Prudnikov, O. N.; Taichenachev, A. V.; Tumaikin, A. M.; Yudin, V. I.

    2007-01-01

    Generally, conditions for deep sub-Doppler laser cooling do not match conditions for strong atomic localization, that takes place in a deeper optical potential and leads to higher temperature. Moreover, for a given detuning in a deep optical potential the secular approximation, which is frequently used for a quantum description of laser cooling, fails. Here we investigate the atomic localization in optical potential, using a full quantum approach for atomic density matrix beyond the secular approximation. It is shown that laser cooling in a deep optical potential, created by a light field with polarization gradients, can be used as an alternative method for the formation of high contrast spatially localized structures of atoms for the purposes of atom lithography and atomic nanofabrication. Finally, we analyze possible limits for the width and contrast of localized atomic structures that can be reached in this type of light mask

  3. Polarization-angle dependence of photoluminescence intensity of ordered GaInP{sub 2} layers: observation of polarization memory

    Energy Technology Data Exchange (ETDEWEB)

    Prutskij, T.; Brito-Orta, R. [Instituto de Ciencias, BUAP, Puebla (Mexico); Pelosi, C. [IMEM/CNR, Parma (Italy)

    2008-09-15

    We compare measured and calculated polarization-angle dependencies of the intensity of the photoluminescence emission from MOVPE-grown GaInP{sub 2} layers with different ordering parameters. We measured the polarization-angle dependencies of the emission propagating along the [001],[110] and [1 anti 10] directions at room temperature. Symmetry considerations were used to calculate the dependence of the relative intensity of the PL emission which was linearly polarized along different directions and to estimate the value of the valence-band splitting by fitting the measured dependencies with calculated curves. An intriguing influence of the polarization of the exciting beam on the relative amount of the polarized PL emission was observed in the emission from the (110) plane. (copyright 2008 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim) (orig.)

  4. Polarization dependent asymmetric magneto-resistance features in nanocrystalline diamond films

    International Nuclear Information System (INIS)

    Bhattacharyya, Somnath; Churochkin, Dmitry

    2014-01-01

    Polar angle-dependence of magneto-resistance (AMR) in heavily nitrogen-incorporated ultra-nanocrystalline diamond (UNCD) films is recorded by applying high magnetic fields, which shows strong anisotropic features at low temperatures. The temperature-dependence of MR and AMR can reveal transport in the weak-localization regime, which is explained by using a superlattice model for arbitrary values of disorder and angles. While a propagative Fermi surface model explains the negative MR features for low degree of disorder the azimuthal angle-dependent MR shows field dependent anisotropy due to the aligned conducting channels on the layers normal to film growth direction. The analysis of MR and AMR can extract the temperature dependence of dephasing time with respect to the elastic scattering time which not only establishes quasi-two dimensional features in this system but also suggests a potential application in monitoring the performance of UNCD based quantum devices.

  5. Modelling polarization dependent absorption: The vectorial Lambert-Beer law

    Science.gov (United States)

    Franssens, G.

    2014-07-01

    The scalar Lambert-Beer law, describing the absorption of unpolarized light travelling through a linear non-scattering medium, is simple, well-known, and mathematically trivial. However, when we take the polarization of light into account and consider a medium with polarization dependent absorption, we now need a Vectorial Lambert-Beer Law (VLBL) to quantify this interaction. Such a generalization of the scalar Lambert-Beer law appears not to be readily available. A careful study of this topic reveals that it is not a trivial problem. We will see that the VLBL is not and cannot be a straightforward vectorized version of its scalar counterpart. The aim of the work is to present the general form of the VLBL and to explain how it arises. A reasonable starting point to derive the VLBL is the Vectorial Radiative Transfer Equation (VRTE), which models the absorption and scattering of (partially) polarized light travelling through a linear medium. When we turn off scattering, the VRTE becomes an infinitesimal model for the VLBL holding in the medium. By integrating this equation, we expect to find the VLBL. Surprisingly, this is not the end of the story. It turns out that light propagation through a medium with polarization-dependent absorption is mathematically not that trivial. The trickiness behind the VLBL can be understood in the following terms. The matrix in the VLBL, relating any input Stokes vector to the corresponding output Stokes vector, must necessarily be a Mueller matrix. The subset of invertible Mueller matrices forms a Lie group. It is known that this Lie group contains the ortho-chronous Lorentz group as a subgroup. The group manifold of this subgroup has a (well-known) non-trivial topology. Consequently, the manifold of the Lie group of Mueller matrices also has (at least the same, but likely a more general) non-trivial topology (the full extent of which is not yet known). The type of non-trivial topology, possessed by the manifold of (invertible

  6. Strong linkage of polar cod (Boreogadus saida) to sea ice algae-produced carbon: Evidence from stomach content, fatty acid and stable isotope analyses

    Science.gov (United States)

    Kohlbach, Doreen; Schaafsma, Fokje L.; Graeve, Martin; Lebreton, Benoit; Lange, Benjamin Allen; David, Carmen; Vortkamp, Martina; Flores, Hauke

    2017-03-01

    The polar cod (Boreogadus saida) is considered an ecological key species, because it reaches high stock biomasses and constitutes an important carbon source for seabirds and marine mammals in high-Arctic ecosystems. Young polar cod (1-2 years) are often associated with the underside of sea ice. To evaluate the impact of changing Arctic sea ice habitats on polar cod, we examined the diet composition and quantified the contribution of ice algae-produced carbon (αIce) to the carbon budget of polar cod. Young polar cod were sampled in the ice-water interface layer in the central Arctic Ocean during late summer 2012. Diets and carbon sources of these fish were examined using 4 approaches: (1) stomach content analysis, (2) fatty acid (FA) analysis, (3) bulk nitrogen and carbon stable isotope analysis (BSIA) and (4) compound-specific stable isotope analysis (CSIA) of FAs. The ice-associated (sympagic) amphipod Apherusa glacialis dominated the stomach contents by mass, indicating a high importance of sympagic fauna in young polar cod diets. The biomass of food measured in stomachs implied constant feeding at daily rates of ∼1.2% body mass per fish, indicating the potential for positive growth. FA profiles of polar cod indicated that diatoms were the primary carbon source, indirectly obtained via amphipods and copepods. The αIce using bulk isotope data from muscle was estimated to be >90%. In comparison, αIce based on CSIA ranged from 34 to 65%, with the highest estimates from muscle and the lowest from liver tissue. Overall, our results indicate a strong dependency of polar cod on ice-algae produced carbon. This suggests that young polar cod may be particularly vulnerable to changes in the distribution and structure of sea ice habitats. Due to the ecological key role of polar cod, changes at the base of the sea ice-associated food web are likely to affect the higher trophic levels of high-Arctic ecosystems.

  7. Competition and coexistence of polar and non-polar states in Sr1-x Ca x TiO3: an investigation using pressure dependent Raman spectroscopy

    Science.gov (United States)

    Tyagi, Shekhar; Sharma, Gaurav; Sathe, Vasant G.

    2018-03-01

    The competition and cooperation between ferroelectric and anti-ferro-distortion (AFD) instabilities are studied using pressure dependent Raman spectroscopy on polycrystalline powder samples of Sr1-x Ca x TiO3(x  =  0.0, 0.06, 0.25, 0.35). For x  =  0.0 composition, a broad polar mode is detected in the Raman spectra above 6 GPa, while for x  =  0.06 composition, the polar modes appear well above 9 GPa where the AFD modes showed strong suppression. In x  =  0.25 and 0.35 composition, the application of small pressure resulted in the appearance of strong AFD modes suppressing the polar modes. At elevated pressures, re-entrant polar modes are observed along with the broad AFD modes and some new peaks are also observed, signifying the lowering of local symmetry. The reappearance of polar modes is found to be related to pressure induced symmetry disorder at local level, suggesting its electronic origin. The re-entrant polar modes observed at higher pressure values are found to be significantly broad and asymmetric in nature, signifying the development of ferroelectric micro regions/nano domains coexisting with AFD. The lower symmetry at local length scale provides a conducive atmosphere for coexisting AFD and FE instabilities.

  8. Deep Ocean Sound Propagation in Environments with Strong Range Dependence

    Science.gov (United States)

    2010-09-30

    follow carbon dioxide uptake into the ocean from the atmosphere have been modeled to have a small but potentially detectable impact on ocean acoustic...to scattering). This work is being presented at the NPAL workshop. 8. Ambient noise level change due to ocean acidification A simplified model...range dependence. In addition, a study of oceanic acoustic response to acidification has been made. IMPACT/APPLICATIONS The research described

  9. Polarization of high harmonics generated from a hydrogen atom in a strong laser field

    International Nuclear Information System (INIS)

    Melezhik, V.S.

    1996-01-01

    The high harmonic spectrum of a hydrogen atom subject to an intense (>10 13 W/cm 2 ), elliptically polarized laser field is analyzed with a nonperturbative method of global approximation on a subspace grid. Considerable alteration of harmonics polarization with respect to laser polarization is found. 12 refs., 3 figs., 1 tab

  10. Measuring polarization dependent dispersion of non-polarizing beam splitter cubes with spectrally resolved white light interferometry

    Science.gov (United States)

    Csonti, K.; Hanyecz, V.; Mészáros, G.; Kovács, A. P.

    2017-06-01

    In this work we have measured the group-delay dispersion of an empty Michelson interferometer for s- and p-polarized light beams applying two different non-polarizing beam splitter cubes. The interference pattern appearing at the output of the interferometer was resolved with two different spectrometers. It was found that the group-delay dispersion of the empty interferometer depended on the polarization directions in case of both beam splitter cubes. The results were checked by inserting a glass plate in the sample arm of the interferometer and similar difference was obtained for the two polarization directions. These results show that to reach high precision, linearly polarized white light beam should be used and the residual dispersion of the empty interferometer should be measured at both polarization directions.

  11. Multiorbital effects in strong-field ionization and dissociation of aligned polar molecules CH3I and CH3Br

    Science.gov (United States)

    Luo, Sizuo; Zhou, Shushan; Hu, Wenhui; Li, Xiaokai; Ma, Pan; Yu, Jiaqi; Zhu, Ruihan; Wang, Chuncheng; Liu, Fuchun; Yan, Bing; Liu, Aihua; Yang, Yujun; Guo, Fuming; Ding, Dajun

    2017-12-01

    Controlling the molecular axis offers additional ways to study molecular ionization and dissociation in strong laser fields. We measure the ionization and dissociation yields of aligned polar CH3X (X =I , Br) molecules in a linearly polarized femtosecond laser field. The current data show that maximum ionization occurs when the laser polarization is perpendicular to the molecular C -X axis, and dissociation prefers to occur at the laser polarization parallel to the C -X axis. The observed angular distributions suggest that the parent ions are generated by ionization from the HOMO. The angular distribution of fragment ions indicates that dissociation occurs mainly from an ionic excited state produced by ionization from the HOMO-1.

  12. Polarized Line Formation in Arbitrary Strength Magnetic Fields Angle-averaged and Angle-dependent Partial Frequency Redistribution

    Energy Technology Data Exchange (ETDEWEB)

    Sampoorna, M.; Nagendra, K. N. [Indian Institute of Astrophysics, Koramangala, Bengaluru 560 034 (India); Stenflo, J. O., E-mail: sampoorna@iiap.res.in, E-mail: knn@iiap.res.in, E-mail: stenflo@astro.phys.ethz.ch [Institute of Astronomy, ETH Zurich, CH-8093 Zurich (Switzerland)

    2017-08-01

    Magnetic fields in the solar atmosphere leave their fingerprints in the polarized spectrum of the Sun via the Hanle and Zeeman effects. While the Hanle and Zeeman effects dominate, respectively, in the weak and strong field regimes, both these effects jointly operate in the intermediate field strength regime. Therefore, it is necessary to solve the polarized line transfer equation, including the combined influence of Hanle and Zeeman effects. Furthermore, it is required to take into account the effects of partial frequency redistribution (PRD) in scattering when dealing with strong chromospheric lines with broad damping wings. In this paper, we present a numerical method to solve the problem of polarized PRD line formation in magnetic fields of arbitrary strength and orientation. This numerical method is based on the concept of operator perturbation. For our studies, we consider a two-level atom model without hyperfine structure and lower-level polarization. We compare the PRD idealization of angle-averaged Hanle–Zeeman redistribution matrices with the full treatment of angle-dependent PRD, to indicate when the idealized treatment is inadequate and what kind of polarization effects are specific to angle-dependent PRD. Because the angle-dependent treatment is presently computationally prohibitive when applied to realistic model atmospheres, we present the computed emergent Stokes profiles for a range of magnetic fields, with the assumption of an isothermal one-dimensional medium.

  13. Counterintuitive angular shifts in the photoelectron momentum distribution for atoms in strong few-cycle circularly polarized laser pulses

    DEFF Research Database (Denmark)

    Martiny, Christian; Abu-Samha, Mahmoud; Madsen, Lars Bojer

    2009-01-01

    We solve the three-dimensional time-dependent Schrödinger equation for a three-cycle circularly polarized laser pulse interacting with an atom. The photoelectron momentum distributions show counterintuitive shifts, similar to those observed in a recent experiment (Eckle et al 2008 Science 322 1525...

  14. Magnetic field induced strong valley polarization in the three-dimensional topological semimetal LaBi

    Science.gov (United States)

    Kumar, Nitesh; Shekhar, Chandra; Klotz, J.; Wosnitza, J.; Felser, Claudia

    2017-10-01

    LaBi is a three-dimensional rocksalt-type material with a surprisingly quasi-two-dimensional electronic structure. It exhibits excellent electronic properties such as the existence of nontrivial Dirac cones, extremely large magnetoresistance, and high charge-carrier mobility. The cigar-shaped electron valleys make the charge transport highly anisotropic when the magnetic field is varied from one crystallographic axis to another. We show that the electrons can be polarized effectively in these electron valleys under a rotating magnetic field. We achieved a polarization of 60% at 2 K despite the coexistence of three-dimensional hole pockets. The valley polarization in LaBi is compared to the sister compound LaSb where it is found to be smaller. The performance of LaBi is comparable to the highly efficient bismuth.

  15. Polarization-dependent diffraction in all-dielectric, twisted-band structures

    Energy Technology Data Exchange (ETDEWEB)

    Kardaś, Tomasz M.; Jagodnicka, Anna; Wasylczyk, Piotr, E-mail: pwasylcz@fuw.edu.pl [Photonic Nanostructure Facility, Institute of Experimental Physics, Faculty of Physics, University of Warsaw, Pasteura 5, 02-093 Warszawa (Poland)

    2015-11-23

    We propose a concept for light polarization management: polarization-dependent diffraction in all-dielectric microstructures. Numerical simulations of light propagation show that with an appropriately configured array of twisted bands, such structures may exhibit zero birefringence and at the same time diffract two circular polarizations with different efficiencies. Non-birefringent structures as thin as 3 μm have a significant difference in diffraction efficiency for left- and right-hand circular polarizations. We identify the structural parameters of such twisted-band matrices for optimum performance as circular polarizers.

  16. Scale dependence and small-x behaviour of polarized parton distributions

    International Nuclear Information System (INIS)

    Ball, R.D.; Forte, S.; Ridolfi, G.

    1995-01-01

    We discuss perturbative evolution of the polarized structure function g 1 in the (x, Q 2 ) plane, with special regard to the small-x region. We determine g 1 in terms of polarized quark and gluon distributions using coefficient functions to order α s . At small x g 1 then displays substantial scale dependence, which necessarily implies a corresponding scale dependence in the large-x region. This scale dependence has significant consequences for the extraction of the first moment from the experimental data, reducing its value while increasing the error. Conversely, the scale dependence may be used to constrain the size of the polarized gluon distribution. ((orig.))

  17. Polarization signatures of strong gravity in active galactic nuclei accretion discs

    Czech Academy of Sciences Publication Activity Database

    Dovčiak, Michal; Karas, Vladimír; Matt, G.

    2004-01-01

    Roč. 355, č. 3 (2004), s. 1005-1009 ISSN 0035-8711 R&D Projects: GA ČR GA202/02/0735; GA ČR GA205/03/0902 Institutional research plan: CEZ:AV0Z1003909 Keywords : relativity * polarization * galaxies Subject RIV: BN - Astronomy, Celestial Mechanics, Astrophysics Impact factor: 5.238, year: 2004

  18. Strongly transverse-electric-polarized emission from deep ultraviolet AlGaN quantum well light emitting diodes

    Energy Technology Data Exchange (ETDEWEB)

    Reich, Christoph, E-mail: Christoph.Reich@tu-berlin.de; Guttmann, Martin; Wernicke, Tim; Mehnke, Frank; Kuhn, Christian [Institut für Festkörperphysik, Technische Universität Berlin, Hardenbergstr. 36, Berlin 10623 (Germany); Feneberg, Martin; Goldhahn, Rüdiger [Institut für Experimentelle Physik, Otto-von-Guericke-Universität, Universitätsplatz 2, Magdeburg 39106 (Germany); Rass, Jens; Kneissl, Michael [Institut für Festkörperphysik, Technische Universität Berlin, Hardenbergstr. 36, Berlin 10623 (Germany); Ferdinand-Braun-Institut, Leibniz-Institut für Höchstfrequenztechnik, Gustav-Kirchhoff-Str. 4, Berlin 12489 (Germany); Lapeyrade, Mickael; Einfeldt, Sven; Knauer, Arne; Kueller, Viola; Weyers, Markus [Ferdinand-Braun-Institut, Leibniz-Institut für Höchstfrequenztechnik, Gustav-Kirchhoff-Str. 4, Berlin 12489 (Germany)

    2015-10-05

    The optical polarization of emission from ultraviolet (UV) light emitting diodes (LEDs) based on (0001)-oriented Al{sub x}Ga{sub 1−x}N multiple quantum wells (MQWs) has been studied by simulations and electroluminescence measurements. With increasing aluminum mole fraction in the quantum well x, the in-plane intensity of transverse-electric (TE) polarized light decreases relative to that of the transverse-magnetic polarized light, attributed to a reordering of the valence bands in Al{sub x}Ga{sub 1−x}N. Using k ⋅ p theoretical model calculations, the AlGaN MQW active region design has been optimized, yielding increased TE polarization and thus higher extraction efficiency for bottom-emitting LEDs in the deep UV spectral range. Using (i) narrow quantum wells, (ii) barriers with high aluminum mole fractions, and (iii) compressive growth on patterned aluminum nitride sapphire templates, strongly TE-polarized emission was observed at wavelengths as short as 239 nm.

  19. Polarization Dependence Suppression of Optical Fiber Grating Sensor in a π-Shifted Sagnac Loop Interferometer

    Directory of Open Access Journals (Sweden)

    Jaebum Son

    2010-04-01

    Full Text Available In the sensing applications of optical fiber grating, it is necessary to reduce the transmission-type polarization dependence to isolate the sensing parameter. It is experimentally shown that the polarization-dependent spectrum of acousto-optic long-period fiber grating sensors can be suppressed in the transmission port of a π-shifted Sagnac loop interferometer. General expressions for the transmittance and reflectance are derived for transmission-type, reflection-type, and partially reflecting/transmitting-type polarization-dependent optical devices. The compensation of polarization dependence through the counter propagation in the Sagnac loop interferometer is quantitatively measured for a commercial in-line polarizer and an acousto-optic long-period fiber grating sensor.

  20. GBT Detection of Polarization-Dependent HI Absorption and HI Outflows in Local ULIRGs and Quasars

    Science.gov (United States)

    Teng, Stacy H.; Veilleux, Sylvain; Baker, Andrew J.

    2013-01-01

    We present the results of a 21-cm HI survey of 27 local massive gas-rich late-stage mergers and merger remnants with the Green Bank Telescope (GBT). These remnants were selected from the Quasar/ULIRG Evolution Study (QUEST) sample of ultraluminous infrared galaxies (ULIRGs; L(sub 8 - 1000 micron) > 10(exp 12) solar L) and quasars; our targets are all bolometrically dominated by active galactic nuclei (AGN) and sample the later phases of the proposed ULIRG-to-quasar evolutionary sequence. We find the prevalence of HI absorption (emission) to be 100% (29%) in ULIRGs with HI detections, 100% (88%) in FIR-strong quasars, and 63% (100%) in FIR-weak quasars. The absorption features are associated with powerful neutral outflows that change from being mainly driven by star formation in ULIRGs to being driven by the AGN in the quasars. These outflows have velocities that exceed 1500 km/s in some cases. Unexpectedly, we find polarization-dependent HI absorption in 57% of our spectra (88% and 63% of the FIR-strong and FIR-weak quasars, respectively). We attribute this result to absorption of polarized continuum emission from these sources by foreground HI clouds. About 60% of the quasars displaying polarized spectra are radio-loud, far higher than the approx 10% observed in the general AGN population. This discrepancy suggests that radio jets play an important role in shaping the environments in these galaxies. These systems may represent a transition phase in the evolution of gas-rich mergers into "mature" radio galaxies.

  1. Spin dependence studies with the ZGS polarized proton beam

    International Nuclear Information System (INIS)

    Wicklund, A.B.

    1977-01-01

    Selected results are summarized of recent measurements using a polarized proton beam at the Argonne ZGS. The polarized target asymmetry and the beam-target spin correlation are measured in pp→pp at 6 and 12 GeV/c. Asymmetry is slowly varying with energy while spin correlation increases considerably from 6 to 12 GeV/c. The polarized parameters in pp→pp and pn→pn elastic scattering are compared. The data show that pp and pn polarizations tend to approach mirror symmetry as the energy increases. The effective mass spectrometer has been used to study the pp→pπ + n, pn→pπ - p reactions from 2 to 6 GeV/c. For small -t values (-t 2 ) these reactions are dominated by π exchange. At large -t values other mechanisms besides π-exchange become important. The 3-body diffraction dissociation reactions have been measured at 6 GeV/c with hydrogen and deuterium targets. The reactions are pp→pπ + π - (p); pd→pπ + π - (p+n). Comparison of hydrogen and deuterium cross section reveals a considerable coherent contribution of deuterium, which has an approximately 20% larger cross section per nucleon than hydrogen

  2. On the role of strong gravity in polarization from scattering of light in relativistic flows

    Czech Academy of Sciences Publication Activity Database

    Horák, Jiří; Karas, Vladimír

    2006-01-01

    Roč. 365, č. 3 (2006), s. 813-826 ISSN 0035-8711 R&D Projects: GA MŠk(CZ) LC06014; GA AV ČR(CZ) IAA300030510; GA ČR GA205/03/0902 Institutional research plan: CEZ:AV0Z10030501 Keywords : polarization * black hole physics * relativity Subject RIV: BN - Astronomy, Celestial Mechanics, Astrophysics Impact factor: 5.057, year: 2006

  3. In vivo polarization dependant Second and Third harmonic generation imaging of Caenorhabditis elegans pharyngeal muscles

    Science.gov (United States)

    Filippidis, G.; Troulinaki, K.; Fotakis, C.; Tavernarakis, N.

    2009-07-01

    In this study Second and Third harmonic generation (SHG-THG) imaging measurements were performed to the pharyngeal muscles of the nematode Caenorhabditis elegans, in vivo with linearly polarized laser beam. Complementary information about the anatomy of the pharynx and the morphology of the anterior part of the worm were extracted. THG signals proved to have no dependence on incident light polarization, while SHG images are highly sensitive to the changes of the incident linearly polarized light.

  4. Wavelength dependence of light diffusion in strongly scattering macroporous gallium phosphide

    NARCIS (Netherlands)

    Peeters, W.H.; Vellekoop, Ivo Micha; Mosk, Allard; Lagendijk, Aart

    2008-01-01

    We present time-resolved measurements of light transport through strongly scattering macroporous gallium phosphide at various vacuum wavelengths between 705 nm and 855 nm. Within this range the transport mean free path is strongly wavelength dependent, whereas the observed energy velocity is shown

  5. Determination of the Bjorken Sum and Strong Coupling from Polarized Structure Functions

    CERN Document Server

    Altarelli, Guido; Forte, Stefano; Ridolfi, G; Altarelli, Guido; Ball, Richard D.; Forte, Stefano; Ridolfi, Giovanni

    1997-01-01

    We present a NLO perturbative analysis of all available data on the polarized structure function g_1(x,Q^2) with the aim of making a quantitative test of the validity of the Bjorken sum rule, of measuring \\alpha_s, and of deriving helicity fractions. We take particular care over the small x extrapolation, since it is now known that Regge behaviour is unreliable at perturbative scales. For fixed \\alpha_s we find that if all the most recent data are included g_A=1.18\\pm0.09, confirming the Bjorken sum rule at the 8% level. We further show that the value of \\alpha_s is now reasonably well constrained by scaling violations in the structure function data, despite the fact that it cannot yet be reliably fixed by the value of the Bjorken sum: our final result is \\alpha_s(m_Z) = 0.120+0.010-0.008. We also confirm earlier indications of a sizeable positive gluon polarization in the nucleon.

  6. Onset polarity in bipolar disorder: A strong association between first depressive episode and suicide attempts.

    Science.gov (United States)

    Cremaschi, Laura; Dell'Osso, Bernardo; Vismara, Matteo; Dobrea, Cristina; Buoli, Massimiliano; Ketter, Terence A; Altamura, A Carlo

    2017-02-01

    The role of onset polarity (OP) in patients with bipolar disorder (BD) has been increasingly investigated over the last few years, for its clinical, prognostic, and therapeutic implications. The present study sought to assess whether OP was associated with specific correlates, in particular with a differential suicidal risk in BD patients. A sample of 362 recovered BD patients was dichotomized by OP: depressed (DO) or elevated onset (EO: hypomanic/manic/mixed). Socio-demographic and clinical variables were compared between the subgroups. Additionally, binary logistic regression was performed to assess features associated with OP. DO compared with EO patients had older current age and were more often female, but less often single and unemployed. Clinically, DO versus EO had a more than doubled rate of suicide attempts, as well as significantly higher rates of BD II diagnosis, lifetime stressful events, current psychotropics and antidepressants use, longer duration of the most recent episode (more often depressive), but lower rates of psychosis and involuntary commitments. Retrospective design limiting the accurate assessment of total number of prior episodes of each polarity. Our results support the influence of OP on BD course and outcome. Moreover, in light of the relationship between DO and a higher rate of suicide attempts, further investigation may help clinicians in identifying patients at higher risk of suicide attempts. Copyright © 2016. Published by Elsevier B.V.

  7. Polarization Dependence of Surface Enhanced Raman Scattering on a Single Dielectric Nanowire

    Directory of Open Access Journals (Sweden)

    Hua Qi

    2012-01-01

    Full Text Available Our measurements of surface enhanced Raman scattering (SERS on Ga2O3 dielectric nanowires (NWs core/silver composites indicate that the SERS enhancement is highly dependent on the polarization direction of the incident laser light. The polarization dependence of the SERS signal with respect to the direction of a single NW was studied by changing the incident light angle. Further investigations demonstrate that the SERS intensity is not only dependent on the direction and wavelength of the incident light, but also on the species of the SERS active molecule. The largest signals were observed on an NW when the incident 514.5 nm light was polarized perpendicular to the length of the NW, while the opposite phenomenon was observed at the wavelength of 785 nm. Our theoretical simulations of the polarization dependence at 514.5 nm and 785 nm are in good agreement with the experimental results.

  8. Flatland Position-Dependent-Mass: Polar Coordinates, Separability and Exact Solvability

    Science.gov (United States)

    Mazharimousavi, S. Habib; Mustafa, Omar

    2010-10-01

    The kinetic energy operator with position-dependent-mass in plane polar coordinates is obtained. The separability of the corresponding Schrödinger equation is discussed. A hypothetical toy model is reported and two exactly solvable examples are studied.

  9. Wavelength Dependence of the Polarization Singularities in a Two-Mode Optical Fiber

    Directory of Open Access Journals (Sweden)

    V. V. G. Krishna Inavalli

    2012-01-01

    Full Text Available We present here an experimental demonstration of the wavelength dependence of the polarization singularities due to linear combination of the vector modes excited directly in a two-mode optical fiber. The coherent superposition of the vector modes excited by linearly polarized Gaussian beam as offset skew rays propagated in a helical path inside the fiber results in the generation of phase singular beams with edge dislocation in the fiber output. The polarization character of these beams is found to change dramatically with wavelength—from left-handed elliptically polarized edge dislocation to right-handed elliptically polarized edge-dislocation through disclinations. The measured behaviour is understood as being due to intermodal dispersion of the polarization corrections to the propagating vector modes, as the wavelength of the input beam is scanned.

  10. Dependence of extinction cross-section on incident polarization state and particle orientation

    International Nuclear Information System (INIS)

    Yang Ping; Wendisch, Manfred; Bi Lei; Kattawar, George; Mishchenko, Michael; Hu, Yongxiang

    2011-01-01

    This note reports on the effects of the polarization state of an incident quasi-monochromatic parallel beam of radiation and the orientation of a hexagonal ice particle with respect to the incident direction on the extinction process. When the incident beam is aligned with the six-fold rotational symmetry axis, the extinction is independent of the polarization state of the incident light. For other orientations, the extinction cross-section for linearly polarized light can be either larger or smaller than its counterpart for an unpolarized incident beam. Therefore, the attenuation of a quasi-monochromatic radiation beam by an ice cloud depends on the polarization state of the beam if ice crystals within the cloud are not randomly oriented. Furthermore, a case study of the extinction of light by a quartz particle is also presented to illustrate the dependence of the extinction cross-section on the polarization state of the incident light.

  11. Polarization-dependent electromagnetic responses in an A-shape metasurface.

    Science.gov (United States)

    Zhang, Ning; Xu, Quan; Li, Shaoxian; Ouyang, Chunmei; Zhang, Xueqian; Li, Yanfeng; Gu, Jianqiang; Tian, Zhen; Han, Jiaguang; Zhang, Weili

    2017-08-21

    We numerically and experimentally demonstrate polarization-dependent terahertz responses in a proposed metasurface of A-shape resonators. With the horizontal polarization incidence, the observed transmission window is formed by two resonance dips, corresponding to the inductive-capacitive resonance at the lower frequency and the high-order antisymmetric resonance at a higher frequency, respectively. When the incident wave is perpendicularly polarized, the transmission window arises from the plasmon-induced transparency spectral response. The origin of the polarization-sensitive resonance properties is revealed by mapping the electric field and terahertz-induced surface current in the proposed metamaterials. Moreover, the influence of the geometry of the A-shape microstructures on the transmission spectra is analyzed. These polarization-dependent metamaterials may provide more degrees of freedom in tuning the electromagnetic responses, thus offering a path toward robust metamaterials design.

  12. Asymmetrical edges induced strong current-polarization in embedded graphene nanoribbons

    Science.gov (United States)

    Li, Kuanhong; Zhang, Xiang-Hua

    2018-05-01

    We investigate the electronic structures and transport properties of the embedded zigzag graphene nanoribbon (E-ZGNR) in hexagonal boron nitride trenches, which are achievable in recent experiments. Our first principles results show that the E-ZGNR has a significant enhanced conductivity relative to common ZGNRs due to the existence of asymmetrical edge structures. Moreover, only one spin-orientation electrons possess a widely opened band gap at the magnetic ground state with anti-ferromagnetic configuration, resulting in a full current-polarization at low bias region. Our findings indicate that the state-of-the-art embedding technology is quite useful for tuning the electronic structure of ZGNR and building possible spin injection and spin filter devices in spintronics.

  13. Polarization-state-dependent attenuation and amplification in a columnar thin film

    Science.gov (United States)

    Mackay, Tom G.; Lakhtakia, Akhlesh

    2017-12-01

    We numerically investigated the plane-wave reflection-transmission characteristics of a columnar thin film (CTF) whose columns are made from a dissipative material but whose void regions are filled with an active material. By computing the reflectances and transmittances, we found that the CTF can simultaneously amplify s-polarized incident light and attenuate p-polarized incident light, or vice versa. This polarization-state-dependent attenuation and amplification phenomenon depends upon the angle of incidence and the thickness of the CTF.

  14. Polarized light modulates light-dependent magnetic compass orientation in birds

    Science.gov (United States)

    Muheim, Rachel; Sjöberg, Sissel; Pinzon-Rodriguez, Atticus

    2016-01-01

    Magnetoreception of the light-dependent magnetic compass in birds is suggested to be mediated by a radical-pair mechanism taking place in the avian retina. Biophysical models on magnetic field effects on radical pairs generally assume that the light activating the magnetoreceptor molecules is nondirectional and unpolarized, and that light absorption is isotropic. However, natural skylight enters the avian retina unidirectionally, through the cornea and the lens, and is often partially polarized. In addition, cryptochromes, the putative magnetoreceptor molecules, absorb light anisotropically, i.e., they preferentially absorb light of a specific direction and polarization, implying that the light-dependent magnetic compass is intrinsically polarization sensitive. To test putative interactions between the avian magnetic compass and polarized light, we developed a spatial orientation assay and trained zebra finches to magnetic and/or overhead polarized light cues in a four-arm “plus” maze. The birds did not use overhead polarized light near the zenith for sky compass orientation. Instead, overhead polarized light modulated light-dependent magnetic compass orientation, i.e., how the birds perceive the magnetic field. Birds were well oriented when tested with the polarized light axis aligned parallel to the magnetic field. When the polarized light axis was aligned perpendicular to the magnetic field, the birds became disoriented. These findings are the first behavioral evidence to our knowledge for a direct interaction between polarized light and the light-dependent magnetic compass in an animal. They reveal a fundamentally new property of the radical pair-based magnetoreceptor with key implications for how birds and other animals perceive the Earth’s magnetic field. PMID:26811473

  15. Polarization dependent nanostructuring of silicon with femtosecond vortex pulse

    Directory of Open Access Journals (Sweden)

    M. G. Rahimian

    2017-08-01

    Full Text Available We fabricated conical nanostructures on silicon with a tip dimension of ∼ 70 nm using a single twisted femtosecond light pulse carrying orbital angular momentum (ℓ=±1. The height of the nano-cone, encircled by a smooth rim, increased from ∼ 350 nm to ∼ 1 μm with the pulse energy and number of pulses, whereas the apex angle remained constant. The nano-cone height was independent of the helicity of the twisted light; however, it is reduced for linear polarization compared to circular at higher pulse energies. Fluid dynamics simulations show nano-cones formation when compressive forces arising from the radial inward motion of the molten material push it perpendicular to the surface and undergo re-solidification. Simultaneously, the radial outward motion of the molten material re-solidifies after reaching the cold boundary to form a rim. Overlapping of two irradiated spots conforms to the fluid dynamics model.

  16. Spin polarization in high density quark matter under a strong external magnetic field

    DEFF Research Database (Denmark)

    Tsue, Yasuhiko; Da Providência, João; Providência, Constança

    2016-01-01

    In high density quark matter under a strong external magnetic field, possible phases are investigated by using the two-flavor Nambu-Jona-Lasinio (NJL) model with tensor-type four-point interaction between quarks, as well as the axial-vector-type four-point interaction. In the tensor-type interact......In high density quark matter under a strong external magnetic field, possible phases are investigated by using the two-flavor Nambu-Jona-Lasinio (NJL) model with tensor-type four-point interaction between quarks, as well as the axial-vector-type four-point interaction. In the tensor...... phase appears in the wide range of the quark chemical potential. In both the interactions, the quark mass in zero and small chemical potential regions increases which indicates that the chiral symmetry breaking is enhanced, namely the magnetic catalysis occurs....

  17. Sugar-Based Polyamides: Self-Organization in Strong Polar Organic Solvents.

    Science.gov (United States)

    Rosu, Cornelia; Russo, Paul S; Daly, William H; Cueto, Rafael; Pople, John A; Laine, Roger A; Negulescu, Ioan I

    2015-09-14

    Periodic patterns resembling spirals were observed to form spontaneously upon unassisted cooling of d-glucaric acid- and d-galactaric acid-based polyamide solutions in N-methyl-N-morpholine oxide (NMMO) monohydrate. Similar observations were made in d-galactaric acid-based polyamide/ionic liquid (IL) solutions. The morphologies were investigated by optical, polarized light and confocal microscopy assays to reveal pattern details. Differential scanning calorimetry was used to monitor solution thermal behavior. Small- and wide-angle X-ray scattering data reflected the complex and heterogeneous nature of the self-organized patterns. Factors such as concentration and temperature were found to influence spiral dimensions and geometry. The distance between rings followed a first-order exponential decay as a function of polymer concentration. Fourier-Transform Infrared Microspectroscopy analysis of spirals pointed to H-bonding between the solvent and the pendant hydroxyl groups of the glucose units from the polymer backbone. Tests on self-organization into spirals of ketal-protected d-galactaric acid polyamides in NMMO monohydrate confirmed the importance of the monosaccharide's pendant free hydroxyl groups on the formation of these patterns. Rheology performed on d-galactaric-based polyamides at high concentration in NMMO monohydrate solution revealed the optimum conditions necessary to process these materials as fibers by spinning. The self-organization of these sugar-based polyamides mimics certain biological materials.

  18. Turbulence measurements in the vicinity of a strong polar jet during POLSTRACC/GWLCYCLE II/SALSA, 2016

    Science.gov (United States)

    Bramberger, Martina; Dörnbrack, Andreas; Rapp, Markus; Gemsa, Steffen; Raynor, Kevin

    2017-04-01

    In January 2016, the combined POLar STRAtosphere in a Changing Climate (POLSTRACC), Investigation of the life cycle of gravity waves (GW-LCYCLE) II and Seasonality of Air mass transport and origin in the Lowermost Stratosphere (SALSA) campaign, shortly abbreviated as PGS, took place in Kiruna, Sweden. During this campaign, on 31 January 2016, a strong polar jet with horizontal wind speeds up to 100 m/s was located above northern Great Britain. The research flight PGS12 lead the High Altitude LOng range (HALO) aircraft right above the jet streak of this polar jet, a region which is known from theoretical studies for prevalent turbulence. Here, we present a case study in which high-resolution in-situ aircraft measurements are employed to analyse and quantify turbulence in the described region with parameters such as e.g. turbulent kinetic energy and the eddy dissipation rate. This analysis is supported by idealized numerical simulations to determine involved processes for the generation of turbulence. Complementing, forecasts and operational analyses of the integrated forecast system (IFS) of the European Centre for Medium-Range Weather Forecasts (ECMWF) are used to thoroughly analyze the meteorological situation.

  19. Temperature dependence of the photoluminescence polarization of ordered III-V semiconductor alloys

    International Nuclear Information System (INIS)

    Prutskij, T.; Makarov, N.; Attolini, G.

    2016-01-01

    We studied the linear polarization of the photoluminescence (PL) emission of atomically ordered GaInAsP and GaInP alloys with different ordering parameters in the temperature range from 10 to 300 K. The epitaxial layers of these alloys were grown on GaAs and Ge (001) substrates by metal organic vapor phase epitaxy. The polarization of the PL emission propagating along different crystallographic axes depends on the value of biaxial strain in the layer and changes with temperature. We calculated the PL polarization patterns for different propagation directions as a function of biaxial strain using an existing model developed for ternary atomically ordered III-V alloys. Comparing the calculated PL polarization patterns with those obtained experimentally, we separated the variation of the PL polarization due to change of biaxial strain with temperature.

  20. A Polarization-Dependent Frequency-Selective Metamaterial Absorber with Multiple Absorption Peaks

    Directory of Open Access Journals (Sweden)

    Guangsheng Deng

    2017-06-01

    Full Text Available A polarization-dependent, frequency-selective metamaterial (MM absorber based on a single-layer patterned resonant structure intended for F frequency band is proposed. The design, fabrication, and measurement for the proposed absorber are presented. The absorber’s absorption properties at resonant frequencies have unique characteristics of a single-band, dual-band, or triple-band absorption for different polarization of the incident wave. The calculated surface current distributions and power loss distribution provide further understanding of physical mechanism of resonance absorption. Moreover, a high absorption for a wide range of TE-polarized oblique incidence was achieved. Hence, the MM structure realized on a highly flexible polyimide film, makingthe absorber suitable for conformal geometry applications. The proposed absorber has great potential in the development of polarization detectors and polarizers.

  1. Spin dynamics and spin-dependent recombination of a polaron pair under a strong ac drive

    Science.gov (United States)

    Malla, Rajesh K.; Raikh, M. E.

    2017-08-01

    We study theoretically the recombination within a pair of two polarons in magnetic field subject to a strong linearly polarized ac drive. Strong drive implies that the Zeeman frequencies of the pair partners are much smaller than the Rabi frequency, so that the rotating wave approximation does not apply. What makes the recombination dynamics nontrivial is that the partners recombine only when they form a singlet S . By admixing singlet to triplets, the drive induces the triplet recombination as well. We calculate the effective decay rate of all four spin modes. Our main finding is that, under the strong drive, the major contribution to the decay of the modes comes from short time intervals when the driving field passes through zero. When the recombination time in the absence of drive is short, fast recombination from S leads to anomalously slow recombination from the other spin states of the pair. We show that, with strong drive, this recombination becomes even slower. The corresponding decay rate falls off as a power law with the amplitude of the drive.

  2. Magnetization-dependent viscosity in brute-force-polarized liquid 3He

    DEFF Research Database (Denmark)

    Vermeulen, G.A.; Schuhl, A.; Joffrin, J.

    1988-01-01

    A new method to measure the magnetization dependence of the viscosity in polarized liquid He3 is presented. The magnetization is obtained by "brute-force polarization" at 45 mK in magnetic fields up to 11 T; it is subsequently destroyed by saturation of the NMR signal. Our result, a relative...... increase of the viscosity of (31.5)×10-3 at 3.9% polarization and a pressure of 30 bars, disagrees with a prediction based on the "nearly metamagnetic" model....

  3. Spin dependent fragmentation functions for heavy flavor baryons and single heavy hyperon polarization

    CERN Document Server

    Goldstein, G R

    2001-01-01

    Spin dependent fragmentation functions for heavy flavor quarks to fragment into heavy baryons are calculated in a quark-diquark model. The production of intermediate spin 1/2 and 3/2 excited states is explicity included. $\\Lambda_b$ , $\\Lambda_c$ and $\\Xi_c$ production rate and polarization at LEP energies are calculated and, where possible, compared with experiment. A different approach, also relying on a heavy quark-diquark model, is proposed for the small momentum transfer inclusive production of polarized heavy flavor hyperons. The predicted $\\Lambda_c$ polarization is roughly in agreement with experiment.

  4. Orientation and thickness dependence of magnetization at the interfacesof highly spin-polarized manganite thin films

    Energy Technology Data Exchange (ETDEWEB)

    Chopdekar, Rajesh V.; Arenholz, Elke; Suzuki, Y.

    2008-08-18

    We have probed the nature of magnetism at the surface of (001), (110) and (111)-oriented La{sub 0.7}Sr{sub 0.3}MnO{sub 3} thin films. The spin polarization of La{sub 0.7}Sr{sub 0.3}MnO{sub 3} thin films is not intrinsically suppressed at all surfaces and interfaces but is highly sensitive to both the epitaxial strain state as well as the substrate orientation. Through the use of soft x-ray spectroscopy, the magnetic properties of (001), (110) and (111)-oriented La{sub 0.7}Sr{sub 0.3}MnO{sub 3}/SrTiO{sub 3} interfaces have been investigated and compared to bulk magnetometry and resistivity measurements. The magnetization of (110) and (111)-oriented La{sub 0.7}Sr{sub 0.3}MnO{sub 3}/SrTiO{sub 3} interfaces are more bulk-like as a function of thickness whereas the magnetization at the (001)-oriented La{sub 0.7}Sr{sub 0.3}MnO{sub 3}/SrTiO{sub 3} interface is suppressed significantly below a layer thickness of 20 nm. Such findings are correlated with the biaxial strain state of the La{sub 0.7}Sr{sub 0.3}MnO{sub 3} films; for a given film thickness it is the tetragonal distortion of (001) La{sub 0.7}Sr{sub 0.3}MnO{sub 3} that severely impacts the magnetization, whereas the trigonal distortion for (111)-oriented films and monoclinic distortion for (110)-oriented films have less of an impact. These observations provide evidence that surface magnetization and thus spin polarization depends strongly on the crystal surface orientation as well as epitaxial strain.

  5. Asymptotic dependence of Gross–Tulub polaron ground-state energy in the strong coupling region

    Directory of Open Access Journals (Sweden)

    N.I. Kashirina

    2017-12-01

    Full Text Available The properties of translationally invariant polaron functional have been investigated in the region of strong and extremely strong coupling. It has been shown that the Gross–Tulub polaron functional obtained earlier using the methods of field theory was derived only for the region , where is the Fröhlich constant of the electron-phonon coupling. Various representations of exact and approximate polaron functionals have been considered. Asymptotic dependences of the polaron energy have been obtained using a functional extending the Gross–Tulub functional to the region of extremely strong coupling. The asymptotic dependence of polaron energies for an extremely strong coupling are (for the one-parameter variational function fk, and (for a two-parameter function . It has been shown that the virial theorem 1:3:4 holds for the two-parameter function . Minimization of the approximate functional obtained by expanding the exact Gross–Tulub functional in a series on leads to a quadratic dependence of the polaron energy. This approximation is justified for . For a two-parameter function , the corresponding dependence has the form . However, the use of approximate functionals, in contrast to the strict variational procedure, when the exact polaron functional varies, does not guarantee obtaining the upper limit for the polaron energy.

  6. Interpretation of the temperature dependence of the strong visible photoluminescence of porous silicon

    Energy Technology Data Exchange (ETDEWEB)

    Finkbeiner, S. [Max-Planck-Institut fuer Festkoerperforschung, Heisenbergstrasse 1, 70569 Stuttgart (Germany); Weber, J. [Max-Planck-Institut fuer Festkoerperforschung, Heisenbergstrasse 1, 70569 Stuttgart (Germany)

    1995-01-15

    The temperature dependence of the strong visible photoluminescence (550-850nm) is studied in differently prepared porous silicon samples. The variation in the photoluminescence intensity with temperature is a result of a decrease in the radiative decay time and an increase in the non-radiative recombination process with increasing temperatures. The strong visible photoluminescence is interpreted by a recombination of singlet and triplet excitons. The singlet-triplet splitting is comparable for all samples but depends on the detection wavelength and on sample preparation. We present similar data for the recombination process in siloxene which supports the model of a common origin of the strong visible photoluminescence in these very differently prepared samples. ((orig.))

  7. Polarization dependent micro-structuring of silicon with a femtosecond laser

    International Nuclear Information System (INIS)

    Al-Khazraji, H.; Bhardwaj, V.R.

    2015-01-01

    Highlights: • We demonstrate polarization sensitive rim formation around an ablation crater in silicon. • In n-type and intrinsic silicon, the rim height asymmetry is along laser polarization. • In p-type silicon, the rim height asymmetry is perpendicular to laser polarization. • Field enhancement during light-plasma interaction causes asymmetric energy deposition. • Motion of the molten material from the ablation center causes asymmetric rim formation. - Abstract: We experimentally demonstrate formation of a sub-micron rim around femtosecond laser ablated crater on silicon whose height and width were sensitive to laser polarization. Except for circularly polarized light we show that the rim height and width were asymmetric – larger along the direction of the laser polarization for n-type and intrinsic silicon, while in p-type silicon the asymmetry was perpendicular. Polarization dependent rim formation is attributed to the transient light–plasma interaction that gives rise to local-field enhancements resulting in an asymmetric electron density and energy deposition. Picoseconds later when the electron energy is transferred to the lattice, the asymmetry is retained in the temperature distribution within the interaction region. The temperature distribution eventually leads to non-symmetric radial outward fluid motion of a thin layer of molten material from the centre of the ablation crater that subsequently re-solidifies on a nanosecond timescale.

  8. Frequency-Dependent Solvent Impedance and Colloid Microelectrophoresis Measurements in Partially Polar Solvents.

    Science.gov (United States)

    Hayden, Edward; Aljabal, Zena; Yethiraj, Anand

    2017-05-16

    We carry out frequency-dependent solvent impedance measurements and alternating current (ac) colloid microelectrophoresis experiments in partially polar solvents in the low-frequency regime (0.25 Hz ≤ f ≤ 10 Hz). Solvent electrode polarization effects are quantified first in partially polar solvent mixtures containing bromocyclohexane (CHB). We find that the polarization capacitance from electrode polarization exhibits a clear power law behavior C p = C p0 f -m with power law exponent m = 0.25 ± 0.04. Once we account for electrode polarization effects, we are able to obtain quantitative mobilities in the low-frequency regime from our ac microelectrophoresis measurements; for these measurements, we use poly(methyl methacrylate colloids that are gravitationally confined to a plane while suspended in a low-polar solvent mixture of cis-trans decahydronapthalene and CHB. We find that the dimensionless electrophoretic mobility is constant, consistent with expectations for frequencies below the ion-diffusion frequency, and has a value E = 1.6 ± 0.4.

  9. On the temperature dependence of the spontaneous polarization of lithium niobate and lithium tantalate

    International Nuclear Information System (INIS)

    Ismailzade, I.G.; Ismailov, R.M.

    1980-01-01

    The temperature dependence of spontaneous polarization Psub(s)(T) of LiNbO 3 and LiTaO 3 ferroelectrics is studied by the precision X-ray diffraction method up to the Curie temperature - 1140 and 650 deg C, respectively. It is shown that for LiTaO 3 a deviation from continuous variation of spontaneous polarization with temperature is observed, expressing itself more disticntly at temperatures corresponding to intermediate ferroelectric phase transitions. The Psub(s)(T) obtained has whown that up to 210 deg C the value of LiNbO 3 spontaneous polarization practically remains constant and it decreases with the temperature increase, and near the phase transition temperature (transition of the first order) Psub(s)(T) is 40% of spontaneous polarization at room temperature. As in the case of lithium tantalate stepwise changes of Psub(s)(T) for LiNbO 3 are observed

  10. Dependence of polar effect on parameters of coaxial plasma-erosive switches

    International Nuclear Information System (INIS)

    Bystritskij, V.M.; Ivanov, I.B.; Krasik, Ya.E.; Ryzhakin, N.N.; Sinebryukhov, A.A.; Tolmacheva, V.G.

    1988-01-01

    The results of experimental investigations and numerical simulation of the polar effect in a coaxial plasma-erosive switch (PES) established in a circuit of a strong-current nanosecond accelerator are presented. PES characteristics (energy losses, impedance, rate of its increase, etc.) are investigated depending on mutual direction of accelerator current and plasma flow as well as on the cathode radius in the PES region. It is experimentally shown that the magnetic fields near the cathode determined by this electrode radius influences mainly on PES characteristics. Mutual direction of accelerator current and plasma flow is the second significance factor influencing on PES characteristics. The optimal mode of PES operation is realized when providing the less with respect to the positive electrode, cathode radius and coinciding in direction accelerator current and plasma flow. Numerical simulation of dynamic processes in coaxial PES for different ratios of cathode and anode radii and mutual directions of accelerator current and plasma flow gives qualitative agreement with the experimental results

  11. Polarization dependence of two-photon transition intensities in rare-earth doped crystals

    Energy Technology Data Exchange (ETDEWEB)

    Le Nguyen, An-Dien [Univ. of California, Berkeley, CA (United States)

    1996-05-01

    A polarization dependence technique has been developed as a tool to investigate phonon scattering (PS), electronic Raman scattering (ERS), and two-photon absorption (TPA) transition intensities in vanadate and phosphate crystals. A general theory for the polarization dependence (PD) of two-photon transition intensities has been given. Expressions for the polarization dependent behavior of two-photon transition intensities have been tabulated for the 32 crystallographic point groups. When the wavefunctions for the initial and final states of a rare-earth doped in crystals are known, explicit PD expressions with no unknown parameters can be obtained. A spectroscopic method for measuring and interpreting phonon and ERS intensities has been developed to study PrVO4, NdVO4, ErVO4, and TmVO4 crystals. Relative phonon intensities with the polarization of the incident and scattered light arbitrarily varied were accurately predicted and subsequently used for alignment and calibration in ERS measurements in these systems for the first time. Since ERS and PS intensities generally follow different polarization curves as a function of polar angles, the two can be uniquely identified by comparing their respective polarization behavior. The most crucial application of the technique in ERS spectroscopy is the establishment of a stringent test for the Axe theory. For the first time, the F1/F2 ratio extracted from the experimental fits of the ERS intensities were compared with those predicted by theories which include both the second- and third-order contributions. Relatively good agreement between the fitted values of F1/F2 and the predicted values using the second-order theory has been found.

  12. High-Efficiency Dielectric Metasurfaces for Polarization-Dependent Terahertz Wavefront Manipulation

    KAUST Repository

    Zhang, Huifang

    2017-11-30

    Recently, metasurfaces made up of dielectric structures have drawn enormous attentions in the optical and infrared regimes due to their high efficiency and designing freedom in manipulating light propagation. Such advantages can also be introduced to terahertz frequencies where efficient functional devices are still lacking. Here, polarization-dependent all-silicon terahertz dielectric metasurfaces are proposed and experimentally demonstrated. The metasurfaces are composed of anisotropic rectangular-shaped silicon pillars on silicon substrate. Each metasurface holds dual different functions depending on the incident polarizations. Furthermore, to suppress the reflection loss and multireflection effect in practical applications, a high-performance polarization-independent antireflection silicon pillar array is also proposed, which can be patterned at the other side of the silicon substrate. Such all-silicon dielectric metasurfaces are easy to fabricate and can be very promising in developing next-generation efficient, compact, and low-cost terahertz functional devices.

  13. Temperature dependence of low-frequency polarized Raman scattering spectra in TlInS{sub 2}

    Energy Technology Data Exchange (ETDEWEB)

    Paucar, Raul; Wakita, Kazuki [Electronics and Computer Engineering, Chiba Institute of Technology, Chiba (Japan); Shim, YongGu; Mimura, Kojiro [Graduate School of Engineering, Osaka Prefecture University, Osaka (Japan); Alekperov, Oktay; Mamedov, Nazim [Institute of Physics, Azerbaijan National Academy of Sciences, Baku (Azerbaijan)

    2017-06-15

    In this work, we examined phase transitions in the layered ternary thallium chalcogenide TlInS{sub 2} by studying the temperature dependence of polarized Raman spectra with the aid of the Raman confocal microscope system. The Raman spectra were measured over the temperature range of 77-320 K (which includes the range of successive phase transitions) in the low-frequency region of 35-180 cm{sup -1}. The optical phonons that showed strong temperature dependence were identified as interlayer vibrations related to phase transitions, while the phonons that showed weak temperature dependence were identified as intralayer vibrations. (copyright 2017 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

  14. Reduction of the Thompson scattering cross section in a strong circularly polarized light field in a plasma with the change of its spectrum. “quantum-classical” electron

    Science.gov (United States)

    Korobkin, V. V.; Romanovsky, M. Yu.

    1992-12-01

    It is shown that in a strong circularly polarized laser field a classical electron motion around ions can occur. The scattering of these electrons in a plasma has the Thompson cross section in the limit of strongs field only and for a subrelativistic motion of the electrons. There are non-ion satellites apart from the basic frequency in the scattering spectrum.

  15. arXiv Black hole superradiance and polarization-dependent bending of light

    CERN Document Server

    Plascencia, Alexis D.

    2017-01-01

    An inhomogeneous pseudo-scalar field configuration behaves like an optically active medium. Consequently, if a light ray passes through an axion cloud surrounding a Kerr black hole, it may experience a polarization-dependent bending. We explore the size and relevance of such effect considering both the QCD axion and a generic axion-like particle.

  16. Intensity-dependent change in polarization state of light in normal ...

    Indian Academy of Sciences (India)

    Intensity-dependent change in polarization state of light in normal incidence on an isotropic nonlinear Kerr medium. Hari Prakash Devendra K ... Devendra K Singh2. Department of Physics, University of Allahabad, Allahabad 211 002, India; Department of Physics, Udai Pratap Autonomous College, Varanasi 221 002, India ...

  17. Flatland Position-Dependent-Mass: Polar Coordinates, Separability and Exact Solvability

    Directory of Open Access Journals (Sweden)

    Omar Mustafa

    2010-10-01

    Full Text Available The kinetic energy operator with position-dependent-mass in plane polar coordinates is obtained. The separability of the corresponding Schrödinger equation is discussed. A hypothetical toy model is reported and two exactly solvable examples are studied.

  18. Observation of interface dependent spin polarized photocurrents in InAs/GaSb superlattice

    Energy Technology Data Exchange (ETDEWEB)

    Li, Yuan, E-mail: liyuan12@semi.ac.cn; Liu, Yu; Zhu, Laipan; Qin, Xudong; Wu, Qing; Huang, Wei; Chen, Yonghai, E-mail: yhchen@semi.ac.cn [Key Laboratory of Semiconductor Materials Science, Institute of Semiconductors, Chinese Academy of Sciences, 100083 Beijing (China); Niu, Zhichuan; Xiang, Wei; Hao, Hongyue [The State Key Laboratory of Superlattices and Microstructures, Institute of Semiconductors, Chinese Academy of Sciences, 100083 Beijing (China)

    2015-05-11

    In this letter, we investigated the spin polarized photocurrents excited by mid-infrared radiation and near-infrared radiation, respectively, in InAs/GaSb type II superlattices with different kinds of interfaces. By periodically varying the polarization state of the radiation, we analyzed Rashba-type and Dresselhaus-type spin polarized photocurrents, which present different features depending on the interface types and excitation conditions. Under mid-infrared excitation, the ratio of Rashba-type and Dresselhaus-type spin polarized photocurrents of the superlattice with InSb-like interface is obviously larger than that of the superlattice with GaAs-like interface, the ratio of the superlattice with alternate interface is in the middle. Whereas under near-infrared excitation, the ratios of the three superlattices are nearly the same. Further researches reveal the synactic effects of interface dependent strain and asymmetric interface potential on the spin splitting. Besides, the polarized Raman spectroscopies of these structures were also analyzed.

  19. Observation of interface dependent spin polarized photocurrents in InAs/GaSb superlattice

    International Nuclear Information System (INIS)

    Li, Yuan; Liu, Yu; Zhu, Laipan; Qin, Xudong; Wu, Qing; Huang, Wei; Chen, Yonghai; Niu, Zhichuan; Xiang, Wei; Hao, Hongyue

    2015-01-01

    In this letter, we investigated the spin polarized photocurrents excited by mid-infrared radiation and near-infrared radiation, respectively, in InAs/GaSb type II superlattices with different kinds of interfaces. By periodically varying the polarization state of the radiation, we analyzed Rashba-type and Dresselhaus-type spin polarized photocurrents, which present different features depending on the interface types and excitation conditions. Under mid-infrared excitation, the ratio of Rashba-type and Dresselhaus-type spin polarized photocurrents of the superlattice with InSb-like interface is obviously larger than that of the superlattice with GaAs-like interface, the ratio of the superlattice with alternate interface is in the middle. Whereas under near-infrared excitation, the ratios of the three superlattices are nearly the same. Further researches reveal the synactic effects of interface dependent strain and asymmetric interface potential on the spin splitting. Besides, the polarized Raman spectroscopies of these structures were also analyzed

  20. Brucella Dysregulates Monocytes and Inhibits Macrophage Polarization through LC3-Dependent Autophagy

    Directory of Open Access Journals (Sweden)

    Yang Wang

    2017-06-01

    Full Text Available Brucellosis is caused by infection with Brucella species and exhibits diverse clinical manifestations in infected humans. Monocytes and macrophages are not only the first line of defense against Brucella infection but also a main reservoir for Brucella. In the present study, we examined the effects of Brucella infection on human peripheral monocytes and monocyte-derived polarized macrophages. We showed that Brucella infection led to an increase in the proportion of CD14++CD16− monocytes and the expression of the autophagy-related protein LC3B, and the effects of Brucella-induced monocytes are inhibited after 6 weeks of antibiotic treatment. Additionally, the production of IL-1β, IL-6, IL-10, and TNF-α from monocytes in patients with brucellosis was suppressed through the LC3-dependent autophagy pathway during Brucella infection. Moreover, Brucella infection inhibited macrophage polarization. Consistently, the addition of 3-MA, an inhibitor of LC3-related autophagy, partially restored macrophage polarization. Intriguingly, we also found that the upregulation of LC3B expression by rapamycin and heat-killed Brucella in vitro inhibits M2 macrophage polarization, which can be reversed partially by 3-MA. Taken together, these findings reveal that Brucella dysregulates monocyte and macrophage polarization through LC3-dependent autophagy. Thus, targeting this pathway may lead to the development of new therapeutics against Brucellosis.

  1. Density-dependent electron scattering in photoexcited GaAs in strongly diffusive regime

    DEFF Research Database (Denmark)

    Mics, Zoltán; D’Angio, Andrea; Jensen, Søren A.

    2013-01-01

    In a series of systematic optical pump–terahertz probe experiments, we study the density-dependent electron scattering rate in photoexcited GaAs in the regime of strong carrier diffusion. The terahertz frequency-resolved transient sheet conductivity spectra are perfectly described by the Drude...... model, directly yielding the electron scattering rates. A diffusion model is applied to determine the spatial extent of the photoexcited electron-hole gas at each moment after photoexcitation, yielding the time-dependent electron density, and hence the density-dependent electron scattering time. We find...... that the electron scattering time decreases from 320 to 60 fs, as the electron density changes from 1015 to 1019 cm−3....

  2. A model of the plasma flow and current in Saturn's polar ionosphere under conditions of strong Dungey cycle driving

    Directory of Open Access Journals (Sweden)

    C. M. Jackman

    2006-05-01

    Full Text Available We propose a simple model of the flow and currents in Saturn's polar ionosphere. This model is motivated by theoretical reasoning, and guided quantitatively by in situ field and flow data from space missions, ground-based IR Doppler measurements, and Hubble Space Telescope images. The flow pattern consists of components which represent (1 plasma sub-corotation in the middle magnetosphere region resulting from plasma pick-up and radial transport from internal sources; (2 the Vasyliunas-cycle of internal plasma mass-loss down the magnetospheric tail at higher latitudes; and (3 the polar Dungey-cycle flow driven by the solar wind interaction. Upstream measurements of the interplanetary magnetic field (IMF indicate the occurrence of both extended low-field rarefaction intervals with essentially negligible Dungey-cycle flow, and few-day high-field compression regions in which the Dungey-cycle voltage peaks at a few hundred kV. Here we model the latter conditions when the Dungey-cycle is active, advancing on previous axi-symmetric models which may be more directly applicable to quiet conditions. For theoretical convenience the overall flow pattern is constructed by adding together two components - a purely rotational flow similar to previous axi-symmetric models, and a sun-aligned twin vortex representing the dawn-dusk asymmetry effects associated with the Vasyliunas-and Dungey-cycle flows. We calculate the horizontal ionospheric current associated with the flow and the field-aligned current from its divergence. These calculations show that a sheet of upward-directed field-aligned current flows at the boundary of open field lines which is strongly modulated in local-time by the Dungey-cycle flows. We then consider implications of the field-aligned current for magnetospheric electron acceleration and aurorae using two plasma source populations (hot outer magnetospheric electrons and cool dense magnetosheath electrons. Both sources display a strong dawn

  3. Smoothed solutions in the kinetic theory of e+e- vacuum pair creation in strong laser fields. Linear polarization

    Science.gov (United States)

    Smolyansky, S. A.; Prozorkevich, A. V.; Dmitriev, V. V.; Tarakanov, A. V.

    2014-11-01

    In this paper, the dynamical Schwinger effect of vacuum creation of electron-positron pairs driven by an intense laser pulse is studied on the basis of correct quantum kinetic theory. In the general case, the numerical solutions of corresponding system of kinetic equations exhibit complex time dependence which makes the analysis of the physical processes complicated. In particular, the question of secondary effects, such as creation of annihilation photons from the focus spot of the colliding laser beams, remains an important open problem. In our previous work [S. A. Smolyansky, M. Bonitz and A. V. Prozorkevich, Contrib. Plasma Phys.53 (2013) 788], we presented a perturbation theory which is able to capture the dominant time dependence of the produced electron-positron pair distribution during the pulse (quasiparticle excitations). In the present work, we develop appreciably this approximation scheme. We demonstrate effectiveness of the proposed method for solution of such kind nonstationary problems in the simplest models of the laser field. However, this approach opens perspective for search of the relevant approximate solutions in kinetic theory of the e+e- quasiparticle plasma for the more realistic field models (arbitrary polarization, space inhomogeneous, etc).

  4. Polarization Dependent Dynamics of CO2 Trapped in AN Optical Centrifuge

    Science.gov (United States)

    Toro, Carlos; Echebiri, Geraldine; Liu, Qingnan; Mullin, Amy S.

    2012-06-01

    An optical centrifuge (Yuan {et al}. {PNAS} 2011, 108, 6872) has been employed to prepare carbon dioxide molecules in very high rotational states (``hot'' rotors, J ˜220) in order to investigate how collisions relax ensembles of molecules with an overall angular momentum that is spatially oriented. We have performed polarization-dependent high resolution transient IR absorption measurements to study the spatial dependence of the relaxation dynamics. Our results show that the net angular momentum of the initially centrifuged molecules persists for at least 10 gas kinetic collisions and that the translational energy distributions are dependent on the probe orientation and polarization. These studies indicate that the centrifuged molecules tend to maintain the orientation of their initial angular momentum for the first set of collisions and that relatively large changes in J are involved in the first collisions.

  5. On the penetration of a hot diapir through a strongly temperature-dependent viscosity medium

    Science.gov (United States)

    Daly, S. F.; Raefsky, A.

    1985-01-01

    The ascent of a hot spherical body through a fluid with a strongly temperature-dependent viscosity has been studied using an axisymmetric finite element method. Numerical solutions range over Peclet numbers of 0.1 - 1000 from constant viscosity up to viscosity variations of 100,000. Both rigid and stress-free boundary conditions were applied at the surface of the sphere. The dependence of drag on viscosity variation was shown to have no dependence on the stress boundary condition except for a Stokes flow scaling factor. A Nusselt number parameterization based on the stress-free constant viscosity functional dependence on the Peclet number scaled by a parameter depending on the viscosity structure fits both stress-free and rigid boundary condition data above viscosity variations of 100. The temperature scale height was determined as a function of sphere radius. For the simple physical model studied in this paper pre-heating is required to reduce the ambient viscosity of the country rock to less than 10 to the 22nd sq cm/s in order for a 10 km diapir to penetrate a distance of several radii.

  6. Solar polar magnetic field dependency of geomagnetic activity semiannual variation indicated in the Aa index

    Science.gov (United States)

    Oh, Suyeon; Yi, Yu

    2018-01-01

    Three major hypotheses have been proposed to explain the well-known semiannual variation of geomagnetic activity, maxima at equinoxes and minima at solstices. This study examined whether the seasonal variation of equinoctial geomagnetic activity is different in periods of opposite solar magnetic polarity in order to understand the contribution of the interplanetary magnetic field (IMF) in the Sun-Earth connection. Solar magnetic polarity is parallel to the Earth's polarity in solar minimum years of odd/even cycles but antiparallel in solar minimum years of even/odd cycles. The daily mean of the aa, Aa indices during each solar minimum was compared for periods when the solar magnetic polarity remained in opposite dipole conditions. The Aa index values were used for each of the three years surrounding the solar minimum years of the 14 solar cycles recorded since 1856. The Aa index reflects seasonal variation in geomagnetic activity, which is greater at the equinoxes than at the solstices. The Aa index reveals solar magnetic polarity dependency in which the geomagnetic activity is stronger in the antiparallel solar magnetic polarity condition than in the parallel one. The periodicity in semiannual variation of the Aa index is stronger in the antiparallel solar polar magnetic field period than in the parallel period. Additionally, we suggest the favorable IMF condition of the semiannual variation in geomagnetic activity. The orientation of IMF toward the Sun in spring and away from the Sun in fall mainly contributes to the semiannual variation of geomagnetic activity in both antiparallel and parallel solar minimum years.

  7. Extraordinary Photoluminescence and Strong Temperature/Angle-Dependent Raman Responses in Few-Layer Phosphorene

    OpenAIRE

    Zhang, Shuang; Yang, Jiong; Xu, Renjing; Wang, Fan; Li, Weifeng; Ghufran, Muhammad; Zhang, Yong-wei; Yu, Zongfu; Zhang, Gang; Qin, Qinghua; Lu, Yuerui

    2014-01-01

    Phosphorene is a new family member of two-dimensional materials. We observed strong and highly layer-dependent photoluminescence in few-layer phosphorene (2 to 5 layers). The results confirmed the theoretical prediction that few-layer phosphorene has a direct and layer-sensitive band gap. We also demonstrated that few-layer phosphorene is more sensitive to temperature modulation than graphene and MoS2 in Raman scattering. The anisotropic Raman response in few-layer phosphorene has enabled us ...

  8. Strong temperature dependence of extraordinary magnetoresistance correlated to mobility in a two-contact device

    KAUST Repository

    Sun, Jian

    2012-02-21

    A two-contact extraordinary magnetoresistance (EMR) device has been fabricated and characterized at various temperatures under magnetic fields applied in different directions. Large performance variations across the temperature range have been found, which are due to the strong dependence of the EMR effect on the mobility. The device shows the highest sensitivity of 562ω/T at 75 K with the field applied perpendicularly. Due to the overlap between the semiconductor and the metal shunt, the device is also sensitive to planar fields but with a lower sensitivity of about 20 to 25% of the one to perpendicular fields. © 2012 The Japan Society of Applied Physics.

  9. Intensity dependent waiting time for strong electron trapping events in speckle stimulated raman scatter

    Energy Technology Data Exchange (ETDEWEB)

    Rose, Harvey [Los Alamos National Laboratory; Daughton, W [Los Alamos National Laboratory; Yin, L [Los Alamos National Laboratory

    2009-01-01

    The onset of Stimulated Raman scatter from an intense laser speckle is the simplest experimentally realizable laser-plasma-interaction environment. Despite this data and recent 3D particle simulations, the controlling mechanism at the onset of backscatter in the kinetic regime when strong electron trapping in the daughter Langmuir wave is a dominant nonlinearity is not understood. This paper explores the consequences of assuming that onset is controlled by large thermal fluctuations. A super exponential dependence of mean reflectivity on speckle intensity in the onset regime is predicted.

  10. Crystal fields of porphyrins and phthalocyanines from polarization-dependent 2p-to-3d multiplets

    DEFF Research Database (Denmark)

    Johnson, Phillip S.; García Lastra, Juan Maria; Kennedy, Colton K.

    2014-01-01

    Polarization-dependent X-ray absorption spectroscopy is combined with density functional calculations and atomic multiplet calculations to determine the crystal field parameters 10Dq, Ds, and Dt of transition metal phthalocyanines and octaethylporphyrins (Mn, Fe, Co, Ni). The polarization depende...

  11. Reduction of the Thomson scattering cross-section in a strong circularly polarized light field in plasma with the change of its spectrum

    Science.gov (United States)

    Korobkin, Vladlen V.; Romanovsky, Michael Y.

    1992-06-01

    It is shown that in a strong circularly polarized laser field, classical electron motion around the ions can occur. The non-relativistic scattering by these electrons in plasma has a certain (Thomson) cross-section only in the limit of a very strong field (it is practically the case of relativistic motion of electrons). In a circularly polarized field with an amplitude on the order of the inneratomic one, the cross section of this process is less. In the spectrum that the scattering of this field gives in plasma, there are non-ion satellites along with the basic frequency.

  12. Quantum-well exciton dipolar interaction: Polarization-dependence and Z-LT splitting

    International Nuclear Information System (INIS)

    Nguyen Ba An.

    1996-12-01

    We calculate the exciton dipolar interaction in a semiconductor quantum well. The explicit polarization-dependence, i.e, the dependence on both the exciton dipole moment μ-vector and its inplane wavevector k-vector is derived. The obtained results for the three modes (L, T and Z modes) of the long-range part of the dipolar interaction satisfy the polarization sum rule for any parameters. In the long wavelength limit there is a Z-LT splitting which decreases as the well width increases reflecting a crossover from strict 2D to quasi-2D. A rough crossover from quasi-2D to 3D is also described. (author). 18 refs, 4 figs

  13. Dependence of model-simulated response to ozone depletion on stratospheric polar vortex climatology

    Science.gov (United States)

    Lin, Pu; Paynter, David; Polvani, Lorenzo; Correa, Gustavo J. P.; Ming, Yi; Ramaswamy, V.

    2017-06-01

    We contrast the responses to ozone depletion in two climate models: Community Atmospheric Model version 3 (CAM3) and Geophysical Fuild Dynamics Laboratory (GFDL) AM3. Although both models are forced with identical ozone concentration changes, the stratospheric cooling simulated in CAM3 is 30% stronger than in AM3 in annual mean, and twice as strong in December. We find that this difference originates from the dynamical response to ozone depletion, and its strength can be linked to the timing of the climatological springtime polar vortex breakdown. This mechanism is further supported by a variant of the AM3 simulation in which the southern stratospheric zonal wind climatology is nudged to be CAM3-like. Given that the delayed breakdown of the southern polar vortex is a common bias among many climate models, previous model-based assessments of the forced responses to ozone depletion may have been somewhat overestimated.

  14. GREEN BANK TELESCOPE DETECTION OF POLARIZATION-DEPENDENT H I ABSORPTION AND H I OUTFLOWS IN LOCAL ULIRGs AND QUASARS

    Energy Technology Data Exchange (ETDEWEB)

    Teng, Stacy H. [Observational Cosmology Laboratory, NASA Goddard Space Flight Center, Greenbelt, MD 20771 (United States); Veilleux, Sylvain [Department of Astronomy, University of Maryland, College Park, MD 20742 (United States); Baker, Andrew J., E-mail: stacy.h.teng@nasa.gov [Department of Physics and Astronomy, Rutgers, State University of New Jersey, Piscataway, NJ 08854 (United States)

    2013-03-10

    We present the results of a 21 cm H I survey of 27 local massive gas-rich late-stage mergers and merger remnants with the Robert C. Byrd Green Bank Telescope. These remnants were selected from the Quasar/ULIRG Evolution Study sample of ultraluminous infrared galaxies (ULIRGs; L{sub 8{sub -{sub 1000{sub {mu}m}}}} > 10{sup 12} L{sub Sun }) and quasars; our targets are all bolometrically dominated by active galactic nuclei (AGNs) and sample the later phases of the proposed ULIRG-to-quasar evolutionary sequence. We find the prevalence of H I absorption (emission) to be 100% (29%) in ULIRGs with H I detections, 100% (88%) in FIR-strong quasars, and 63% (100%) in FIR-weak quasars. The absorption features are associated with powerful neutral outflows that change from being mainly driven by star formation in ULIRGs to being driven by the AGN in the quasars. These outflows have velocities that exceed 1500 km s{sup -1} in some cases. Unexpectedly, we find polarization-dependent H I absorption in 57% of our spectra (88% and 63% of the FIR-strong and FIR-weak quasars, respectively). We attribute this result to absorption of polarized continuum emission from these sources by foreground H I clouds. About 60% of the quasars displaying polarized spectra are radio-loud, far higher than the {approx}10% observed in the general AGN population. This discrepancy suggests that radio jets play an important role in shaping the environments in these galaxies. These systems may represent a transition phase in the evolution of gas-rich mergers into ''mature'' radio galaxies.

  15. Polarization-dependent single-beam laser-induced grating-like effects on titanium films

    International Nuclear Information System (INIS)

    Camacho-Lopez, Santiago; Evans, Rodger; Escobar-Alarcon, Luis; Camacho-Lopez, Miguel A.; Camacho-Lopez, Marco A.

    2008-01-01

    In this paper we present results on polarization-dependent laser-induced effects on titanium (Ti) thin films. We irradiated the titanium films, in ambient air, using a nanosecond Nd:YAG laser (532 nm, 9 ns pulse duration, 10 Hz). Using a series of pulses of fluence well below the ablation threshold, it was possible to form grating-like structures, whose grooves run parallel to the linear polarization of the incident beam. No grating-like structures were obtained when circularly polarized light was used. Our results revealed the remarkable formation of tiny (100 nm and even smaller diameter) craters, which self-arrange quasi-periodically along the ridges (never on the valleys) of the grating-like structure. Optical and scanning electron microscopy were used to study the laser-induced changes on the surface of the titanium films. Micro-Raman spectroscopy was used to analyze the irradiated areas on the titanium films. The Raman analysis demonstrated that the grooves in the grating-like structure, build up from the laser-induced oxidation of titanium. This is the first time, to the best of our knowledge, that periodic surface structures are reported to be induced below the ablation threshold regime, with the grooves made of crystalline metal oxide, in this case TiO 2 in the well-known Rutile phase. The laser irradiated areas on the film acquired selective (upon recording polarization) holographic reflectance

  16. Polarization-dependent single-beam laser-induced grating-like effects on titanium films

    Energy Technology Data Exchange (ETDEWEB)

    Camacho-Lopez, Santiago [Departamento de Optica, Centro de Investigacion Cientifica y de Educacion Superior de Ensenada, Km 107 Carretera Tijuana-Ensenada, Ensenada, Baja California 22860 (Mexico)], E-mail: camachol@cicese.mx; Evans, Rodger [Departamento de Optica, Centro de Investigacion Cientifica y de Educacion Superior de Ensenada, Km 107 Carretera Tijuana-Ensenada, Ensenada, Baja California 22860 (Mexico); Escobar-Alarcon, Luis [Departamento de Fisica, Instituto Nacional de Investigaciones Nucleares, Apdo. Postal 18-1027, Mexico DF 11801 (Mexico); Camacho-Lopez, Miguel A. [Facultad de Medicina, Universidad Autonoma del Estado de Mexico, Paseo Tollocan s/n, esq. Jesus Carranza, Toluca, Estado de Mexico 50120 (Mexico); Camacho-Lopez, Marco A. [Facultad de Quimica, Universidad Autonoma del Estado de Mexico, Tollocan s/n, esq. Paseo Colon, Toluca, Estado de Mexico, 50110 (Mexico)

    2008-12-30

    In this paper we present results on polarization-dependent laser-induced effects on titanium (Ti) thin films. We irradiated the titanium films, in ambient air, using a nanosecond Nd:YAG laser (532 nm, 9 ns pulse duration, 10 Hz). Using a series of pulses of fluence well below the ablation threshold, it was possible to form grating-like structures, whose grooves run parallel to the linear polarization of the incident beam. No grating-like structures were obtained when circularly polarized light was used. Our results revealed the remarkable formation of tiny (100 nm and even smaller diameter) craters, which self-arrange quasi-periodically along the ridges (never on the valleys) of the grating-like structure. Optical and scanning electron microscopy were used to study the laser-induced changes on the surface of the titanium films. Micro-Raman spectroscopy was used to analyze the irradiated areas on the titanium films. The Raman analysis demonstrated that the grooves in the grating-like structure, build up from the laser-induced oxidation of titanium. This is the first time, to the best of our knowledge, that periodic surface structures are reported to be induced below the ablation threshold regime, with the grooves made of crystalline metal oxide, in this case TiO{sub 2} in the well-known Rutile phase. The laser irradiated areas on the film acquired selective (upon recording polarization) holographic reflectance.

  17. Determination of scattering coefficient considering wavelength and absorption dependence of anisotropy factor measured by polarized beam for biological tissues

    Science.gov (United States)

    Fukutomi, D.; Ishii, K.; Awazu, K.

    2015-12-01

    Anisotropy factor g, one of the optical properties of biological tissues, is the most important parameter to accurately determine scattering coefficient μs in the inverse Monte Carlo (iMC) simulation. It has been reported that g has wavelength and absorption dependence, however, there are few attempts in order to calculate μs of biological tissue considering the wavelength and absorption dependence of g. In this study, the scattering angular distributions of biological tissue phantoms were measured in order to determine g by using goniometric measurements with three polarization conditions at strongly and weakly absorbing wavelengths of hemoglobin. Then, optical properties, especially, μs were measured by integrating sphere measurements and iMC simulation in order to confirm the influence of measured g on optical properties in comparison of with general value of g (0.9) for soft biological tissue. Consequently, it was found that μs was overestimated at strongly absorbing wavelength, however, μs was underestimated at weakly absorbing wavelength if the g was not considered its wavelength and absorption dependence.

  18. Extraordinary photoluminescence and strong temperature/angle-dependent Raman responses in few-layer phosphorene.

    Science.gov (United States)

    Zhang, Shuang; Yang, Jiong; Xu, Renjing; Wang, Fan; Li, Weifeng; Ghufran, Muhammad; Zhang, Yong-Wei; Yu, Zongfu; Zhang, Gang; Qin, Qinghua; Lu, Yuerui

    2014-09-23

    Phosphorene is a new family member of two-dimensional materials. We observed strong and highly layer-dependent photoluminescence in few-layer phosphorene (two to five layers). The results confirmed the theoretical prediction that few-layer phosphorene has a direct and layer-sensitive band gap. We also demonstrated that few-layer phosphorene is more sensitive to temperature modulation than graphene and MoS2 in Raman scattering. The anisotropic Raman response in few-layer phosphorene has enabled us to use an optical method to quickly determine the crystalline orientation without tunneling electron microscopy or scanning tunneling microscopy. Our results provide much needed experimental information about the band structures and exciton nature in few-layer phosphorene.

  19. Fast gain recovery rates with strong wavelength dependence in a non-linear SOA.

    Science.gov (United States)

    Cleary, Ciaran S; Power, Mark J; Schneider, Simon; Webb, Roderick P; Manning, Robert J

    2010-12-06

    We report remarkably fast and strongly wavelength-dependent gain recovery in a single SOA without the aid of an offset filter. Full gain recovery times as short as 9 ps were observed in pump-probe measurements when pumping to the blue wavelength side of a continuous wave probe, in contrast to times of 25 to 30 ps when pumping to the red wavelength side. Experimental and numerical analysis indicate that the long effective length and high gain led to deep saturation of the second half of the SOA by the probe. The consequent absorption of blue-shifted pump pulses in this region resulted in device dynamics analogous to those of the Turbo-Switch.

  20. Strongly enhanced temperature dependence of the chemical potential in FeSe

    Science.gov (United States)

    Rhodes, L. C.; Watson, M. D.; Haghighirad, A. A.; Eschrig, M.; Kim, T. K.

    2017-05-01

    Employing a 10-orbital tight-binding model, we present a set of hopping parameters fitted directly to our latest high-resolution angle-resolved photoemission spectroscopy (ARPES) data for the high-temperature tetragonal phase of FeSe. Using these parameters, we predict a large 10 meV shift of the chemical potential as a function of temperature. To confirm this large temperature dependence, we performed ARPES experiments on FeSe and observed a ˜25 meV rigid shift to the chemical potential between 100 and 300 K. This strong shift has important implications for theoretical models of superconductivity and of nematic order in FeSe materials.

  1. Observations of height-dependent pressure-perturbation structure of a strong mesoscale gravity wave

    Science.gov (United States)

    Starr, David O'C.; Korb, C. L.; Schwemmer, Geary K.; Weng, Chi Y.

    1992-01-01

    Airborne observations using a downward-looking, dual-frequency, near-infrared, differential absorption lidar system provide the first measurements of the height-dependent pressure-perturbation field associated with a strong mesoscale gravity wave. A pressure-perturbation amplitude of 3.5 mb was measured within the lowest 1.6 km of the atmosphere over a 52-km flight line. Corresponding vertical displacements of 250-500 m were inferred from lidar-observed displacement of aerosol layers. Accounting for probable wave orientation, a horizontal wavelength of about 40 km was estimated. Satellite observations reveal wave structure of a comparable scale in concurrent cirrus cloud fields over an extended area. Smaller-scale waves were also observed. Local meteorological soundings are analyzed to confirm the existence of a suitable wave duct. Potential wave-generation mechanisms are examined and discussed. The large pressure-perturbation wave is attributed to rapid amplification or possible wave breaking of a gravity wave as it propagated offshore and interacted with a very stable marine boundary layer capped by a strong shear layer.

  2. Morphology-dependent space charge polarization and dielectric relaxation of CdO nanomorphotypes

    Directory of Open Access Journals (Sweden)

    Paulose Thomas

    2016-12-01

    Full Text Available A versatile approach signifying the morphology-dependent dielectric polarization and relaxation mechanisms of cadmium oxide (CdO nanosphere, nanoflakes and nanoparallelepiped morphotypes as a function of frequency and temperature is presented. Variation of dielectric property is observed due to the changes of space charge/interfacial polarization resulting from the variations of surface to volume ratio of nanomorphology. Accordingly, colossal dielectric constant value has been observed in CdO nanosphere having larger surface to volume ratio. The order of dielectric constant (dc values observed for the present nanomorphologies is: dc of sphere > dc of flakes > dc of parallelepiped resembles the order of surface to volume ratios of the present morphologies respectively. The experimental data of complex impedance values are numerically fitted using theoretical models which provide the information of role of grain resistance on dielectric polarization and Cole–Cole type mechanism of dielectric relaxation process. The activation energies for electron transport are found to be 0.087eV for spheres, 0.074eV for flakes and 0.067 for parallelepiped nanomorphotypes of CdO. The dielectric and impedance spectroscopic analysis of the present material opens up wide scope for morphology-dependent tuning of nanomaterials for electrical applications.

  3. Ascaroside expression in Caenorhabditis elegans is strongly dependent on diet and developmental stage.

    Directory of Open Access Journals (Sweden)

    Fatma Kaplan

    2011-03-01

    Full Text Available The ascarosides form a family of small molecules that have been isolated from cultures of the nematode Caenorhabditis elegans. They are often referred to as "dauer pheromones" because most of them induce formation of long-lived and highly stress resistant dauer larvae. More recent studies have shown that ascarosides serve additional functions as social signals and mating pheromones. Thus, ascarosides have multiple functions. Until now, it has been generally assumed that ascarosides are constitutively expressed during nematode development.Cultures of C. elegans were developmentally synchronized on controlled diets. Ascarosides released into the media, as well as stored internally, were quantified by LC/MS. We found that ascaroside biosynthesis and release were strongly dependent on developmental stage and diet. The male attracting pheromone was verified to be a blend of at least four ascarosides, and peak production of the two most potent mating pheromone components, ascr#3 and asc#8 immediately preceded or coincided with the temporal window for mating. The concentration of ascr#2 increased under starvation conditions and peaked during dauer formation, strongly supporting ascr#2 as the main population density signal (dauer pheromone. After dauer formation, ascaroside production largely ceased and dauer larvae did not release any ascarosides. These findings show that both total ascaroside production and the relative proportions of individual ascarosides strongly correlate with these compounds' stage-specific biological functions.Ascaroside expression changes with development and environmental conditions. This is consistent with multiple functions of these signaling molecules. Knowledge of such differential regulation will make it possible to associate ascaroside production to gene expression profiles (transcript, protein or enzyme activity and help to determine genetic pathways that control ascaroside biosynthesis. In conjunction with findings

  4. Polarization-dependent X-ray absorption spectroscopy of MnWO{sub 4}

    Energy Technology Data Exchange (ETDEWEB)

    Hollmann, Nils; Hu, Zhiwei; Tjeng, Liu Hao [II. Physikalisches Institut, Universitaet zu Koeln (Germany); Bohaty, Ladislav; Becker-Bohaty, Petra [Kristallographisches Institut, Universitaet zu Koeln (Germany); Tanaka, Arata [Department of Quantum Matter, Hiroshima University (Japan)

    2008-07-01

    Multiferroic materials which combine magnetism and ferroelectricity currently attract considerable attention. One of the recently discovered multiferroic materials is MnWO{sub 4} (Huebnerite). It belongs to the group of multiferroics where a spontaneous electric polarization is caused by a spiral magnetic structure with a spin rotation axis not coinciding with the propagation vector. To investigate the details of this astonishing combination of electronic and magnetic properties, we look at the electronic structure with the use of polarization-dependent X-ray absorption spectroscopy on single crystals of MnWO{sub 4}. The analysis of the experimental data on the L-edge of Mn is done by a configuration interaction calculation and is discussed.

  5. The Hanle effect in a random magnetic field. Dependence of the polarization on statistical properties of the magnetic field

    Science.gov (United States)

    Frisch, H.; Anusha, L. S.; Sampoorna, M.; Nagendra, K. N.

    2009-07-01

    Context: The Hanle effect is used to determine weak turbulent magnetic fields in the solar atmosphere, usually assuming that the angular distribution is isotropic, the magnetic field strength constant, and that micro-turbulence holds, i.e. that the magnetic field correlation length is much less than a photon mean free path. Aims: To examine the sensitivity of turbulent magnetic field measurements to these assumptions, we study the dependence of Hanle effect on the magnetic field correlation length, its angular, and strength distributions. Methods: We introduce a fairly general random magnetic field model characterized by a correlation length and a magnetic field vector distribution. Micro-turbulence is recovered when the correlation length goes to zero and macro-turbulence when it goes to infinity. Radiative transfer equations are established for the calculation of the mean Stokes parameters and they are solved numerically by a polarized approximate lambda iteration method. Results: We show that optically thin spectral lines and optically very thick ones are insensitive to the correlation length of the magnetic field, while spectral lines with intermediate optical depths (around 10-100) show some sensitivity to this parameter. The result is interpreted in terms of the mean number of scattering events needed to create the surface polarization. It is shown that the single-scattering approximation holds good for thin and thick lines but may fail for lines with intermediate thickness. The dependence of the polarization on the magnetic field vector probability density function (PDF) is examined in the micro-turbulent limit. A few PDFs with different angular and strength distributions, but equal mean value of the magnetic field, are considered. It is found that the polarization is in general quite sensitive to the shape of the magnetic field strength PDF and somewhat to the angular distribution. Conclusions: The mean field derived from Hanle effect analysis of

  6. Spin-polarization dependent carrier recombination dynamics and spin relaxation mechanism in asymmetrically doped (110) n-GaAs quantum wells

    Science.gov (United States)

    Teng, Lihua; Jiang, Tianran; Wang, Xia; Lai, Tianshu

    2018-05-01

    Carrier recombination and electron spin relaxation dynamics in asymmetric n-doped (110) GaAs/AlGaAs quantum wells are investigated with time-resolved pump-probe spectroscopy. The experiment results reveal that the measured carrier recombination time depends strongly on the polarization of pump pulse. With the same pump photon flux densities, the recombination time of spin-polarized carriers is always longer than that of the spin-balanced carriers except at low pump photon flux densities, this anomaly originates from the polarization-sensitive nonlinear absorption effect. Differing from the traditional views, in the low carrier density regime, the D'yakonov-Perel' (DP) mechanism can be more important than the Bir-Aronov-Pikus (BAP) mechanism, since the DP mechanism takes effect, the spin relaxation time in (110) GaAs QWs is shortened obviously via asymmetric doping.

  7. Ellipticity dependence of the near-threshold harmonics of H2 in an elliptical strong laser field.

    Science.gov (United States)

    Yang, Hua; Liu, Peng; Li, Ruxin; Xu, Zhizhan

    2013-11-18

    We study the ellipticity dependence of the near-threshold (NT) harmonics of pre-aligned H2 molecules using the time-dependent density functional theory. The anomalous maximum appearing at a non-zero ellipticity for the generated NT harmonics can be attributed to multiphoton effects of the orthogonally polarized component of the elliptical driving laser field. Our calculation also shows that the structure of the bound-state, such as molecular alignment and bond length, can be sensitively reflected on the ellipticity dependence of the near-threshold harmonics.

  8. Maxwell-Wagner polarization and frequency-dependent injection at aqueous electrical interfaces.

    Science.gov (United States)

    Desmond, Mitchell; Mavrogiannis, Nicholas; Gagnon, Zachary

    2012-11-02

    We demonstrate a new type of alternating current (ac) interfacial polarization and frequency-dependent fluid displacement phenomenon at a liquid-liquid electrical interface. Two fluid streams--one with a greater electrical conductivity and the other a greater dielectric constant--are made to flow side by side in a microfluidic channel. An ac electric field is applied perpendicular to the interface formed between the liquid lamellae, and fluid is observed to displace across the liquid-liquid interface. The direction and magnitude of this displacement is frequency dependent. At low ac frequency, below the interfacial inverse charge relaxation time, the high-conductivity fluid displaces into the high-dielectric stream. At high frequency the direction of liquid displacement reverses, and the high-dielectric stream injects into the high-conductivity stream. The interfacial crossover frequency where the liquid displacement direction reverses is dependent on differences in electrical properties between the two fluid streams, and is well explained by Maxwell-Wagner polarization mechanics.

  9. Measurements of polarization-dependent angle-resolved light scattering from individual microscopic samples using Fourier transform light scattering

    Science.gov (United States)

    Jung, JaeHwang; Kim, Jinhyung; Seo, Min-Kyo; Park, YongKeun

    2018-03-01

    We present a method to measure the vector-field light scattering of individual microscopic objects. The polarization-dependent optical field images are measured with quantitative phase imaging at the sample plane, and then numerically propagated to the far-field plane. This approach allows the two-dimensional polarization-dependent angle-resolved light scattered patterns from individual object to be obtained with high precision and sensitivity. Using this method, we present the measurements of the polarization-dependent light scattering of a liquid crystal droplet and individual silver nanowires over scattering angles of 50{\\deg}. In addition, the spectroscopic extension of the polarization-dependent angle-resolved light scattering is demonstrated using wavelength-scanning illumination.

  10. Strong composition-dependent disorder in InAs1-xNx alloys

    International Nuclear Information System (INIS)

    Benaissa, H.; Zaoui, A.; Ferhat, M.

    2009-01-01

    We investigate the main causes of disorder in the InAs 1-x N x alloys (x = 0, 0.03125, 0.0625, 0.09375, 0.125, 0.25, 0.5, 0.75, 0.875, 0.90625, 0.9375, 0.96875 and 1). The calculation is based on the density-functional theory in the local-density approximation. We use a plane wave-expansion non-norm conserving ab initio Vanderbilt pseudopotentials. To avoid the difficulty of considering the huge number of atomic configurations, we use an appropriate strategy in which we consider four configurations for a given composition where the N atoms are not randomly distributed. We mainly show that the band gap decreases (increases) rapidly with increasing (decreasing) compositions of N. As a consequence the optical band gap bowing is found to be strong and composition dependent. The obtained compounds, from these alloys, may change from semi-conducting to metal (passing to a negative bowing) and could be useful for device applications, especially at certain composition.

  11. Frequency Dependent Polarization Analysis of Ambient Seismic Noise Recorded at Broadband Seismometers

    Science.gov (United States)

    Koper, K.; Hawley, V.

    2010-12-01

    Analysis of ambient seismic noise is becoming increasingly relevant to modern seismology. Advances in computational speed and storage have made it feasible to analyze years and even decades of continuous seismic data in short amounts of time. Therefore, it is now possible to perform longitudinal studies of station performance in order to identify degradation or mis-installation of seismic equipment. Long-term noise analysis also provides insight into the evolution of the ocean wave climate, specifically whether the frequency and intensity of storms have changed as global temperatures have changed. Here we present a new approach to polarization analysis of seismic noise recorded by three-component seismometers. Essentially, eigen-decomposition of the 3-by-3 Hermitian spectral matrix associated with a sliding window of data is applied to yield various polarization attributes as a function of time and frequency. This in turn yields fundamental information about the composition of seismic noise, such as the extent to which it is polarized, its mode of propagation, and the direction from which it arrives at the seismometer. The polarization attributes can be viewed as function of time or binned over 2D frequency-time space to deduce regularities in the ambient noise that are unbiased by transient signals from earthquakes and explosions. We applied the algorithm to continuous data recorded in 2009 by the seismic station SLM, located in central North America. A rich variety of noise sources was observed. At low frequencies (3 Hz), Rayleigh-type energy was again dominant, in the form of Rg waves created by nearby cultural activities. Analysis of the time dependence of noise power shows that a frequency range of at least 0.02-1.0 Hz (much larger than the microseism band) is sensitive to annual, meteorologically induced sources of noise. We are currently applying our technique to selected seismometers from USArray and the University of Utah Seismic Network.

  12. Laboratory measurements for the wavelength dependence of the linear polarization with the PROGRA2 instruments

    Science.gov (United States)

    Renard, Jean-Baptiste; Hadamcik, Edith; Levasseur-Regourd, Anny-Chantal; Carrasco, Nathalie; Couté, Benoit; Duverger, Vincent; Guerrini, Vincent

    2017-04-01

    Clouds of solid particles are present in many regions of the Solar System (comets, interplanetary dust cloud, planetary atmospheres). These clouds can be remotely studied by the light they scatter. There is a need for a data base of the light scattered by a large variety of samples at different wavelengths to interpret such measurements. The PROGRA2 instruments are used for this purpose. The PROGRA2 instruments, PROGRA2-VIS and PROGRA2-IR, are imaging polarimeters with a rotating arm to change the phase angle (angle between directions of illumination and observation). They allow to retrieve the complete polarization phase function between 10° and 165°. The light sources are at around 550 and 650 nm for PROGRA2-VIS, and 1000 and 1500 nm for PROGRA2-IR. The detectors are cameras, with a spatial resolution between 20 and 40 micrometers per pixel (PROGRA2-IR uses now new high sensitivity cameras). Measurements are conducted in the laboratory by an air draught technique for grains smaller than about 20 micrometers (which can be included in porous aggregates), and during parabolic flights on-board the A300 ZeroG and now the A310 ZeroG for larger grains; these flights campaigns are funded by the French and European Space Agencies. Hundreds of scattering phase functions have been obtained since 20 years, for a large number of samples (sands, silicon carbide, basalt, volcanic ashes, lunar and Martian simulants, tholins, meteoritic material, black carbon, carbonaceous compounds, …); the main results are available at www.icare.univ-lille1.fr/progra2/. Several samples have been already studied by the two instruments, showing a large diversity of wavelength dependences, from close-to-zero dependence for yellow and ocher sand grains to high dependence for silicon carbide and anthracite grains. These variations should be related to the wavelength dependence of the real and imaginary parts of the refractive index of the particles. We present a summary of the main results of

  13. Polarization-dependent Imaging Contrast (PIC) mapping reveals nanocrystal orientation patterns in carbonate biominerals

    Energy Technology Data Exchange (ETDEWEB)

    Gilbert, Pupa U.P.A., E-mail: pupa@physics.wisc.edu [University of Wisconsin-Madison, Departments of Physics and Chemistry, Madison, WI 53706 (United States)

    2012-10-15

    Highlights: Black-Right-Pointing-Pointer Nanocrystal orientation shown by Polarization-dependent Imaging Contrast (PIC) maps. Black-Right-Pointing-Pointer PIC-mapping of carbonate biominerals reveals their ultrastructure at the nanoscale. Black-Right-Pointing-Pointer The formation mechanisms of biominerals is discovered by PIC-mapping using PEEM. -- Abstract: Carbonate biominerals are one of the most interesting systems a physicist can study. They play a major role in the CO{sub 2} cycle, they master templation, self-assembly, nanofabrication, phase transitions, space filling, crystal nucleation and growth mechanisms. A new imaging modality was introduced in the last 5 years that enables direct observation of the orientation of carbonate single crystals, at the nano- and micro-scale. This is Polarization-dependent Imaging Contrast (PIC) mapping, which is based on X-ray linear dichroism, and uses PhotoElectron Emission spectroMicroscopy (PEEM). Here we present PIC-mapping results from biominerals, including the nacre and prismatic layers of mollusk shells, and sea urchin teeth. We describe various PIC-mapping approaches, and show that these lead to fundamental discoveries on the formation mechanisms of biominerals.

  14. A strong angular dependence of magnetic properties of magnetosome chains: Implications for rock magnetism and paleomagnetism

    Science.gov (United States)

    Li, Jinhua; Ge, Kunpeng; Pan, Yongxin; Williams, Wyn; Liu, Qingsong; Qin, Huafeng

    2013-10-01

    Single-domain magnetite particles produced by magnetotactic bacteria (magnetosomes) and aligned in chains are of great interest in the biosciences and geosciences. Here, we investigated angular variation of magnetic properties of aligned Magnetospirillum magneticum AMB-1 cells, each of which contains one single fragmental chain of magnetosomes. With measurements at increasing angles from the chain direction, we observed that (i) the hysteresis loop gradually changes from nearly rectangular to a ramp-like shape (e.g., Bc and remanence decrease), (ii) the acquisition and demagnetization curves of IRM shift toward higher fields (e.g., Bcr increases), and (iii) the FORC diagram shifts toward higher coercivity fields (e.g., Bc,FORC increases). For low-temperature results, compared to unoriented samples, the samples containing aligned chains have a much lower remanence loss of field-cooled (δFC) and zero-field-cooled (δZFC) remanence upon warming through the Verwey transition, higher δ-ratio (δ = δFC/δZFC) for the measurement parallel to the chain direction, and lower δ-ratio, larger δFC and δZFC values for the perpendicular measurement. Micromagnetic simulations confirm the experimental observations and reveal that the magnetization reversal of magnetosome chain appears to be noncoherent at low angles and coherent at high angles. The simulations also demonstrate that the angular dependence of magnetic properties is related to the dispersion degree of individual chains, indicating that effects of anisotropy need to be accounted for when using rock magnetism to identify magnetosomes or magnetofossils once they have been preserved in aligned chains. Additionally, this study experimentally demonstrates an empirical correspondence of the parameter Bc,FORC to Bcr rather than Bc, at least for magnetite chains with strong shape anisotropy. This suggests FORC analysis is a good discriminant of magnetofossils in sediments and rocks.

  15. Suppressing an anti-inflammatory cytokine reveals a strong age-dependent survival cost in mice.

    Directory of Open Access Journals (Sweden)

    Virginia Belloni

    Full Text Available BACKGROUND: The central paradigm of ecological immunology postulates that selection acts on immunity as to minimize its cost/benefit ratio. Costs of immunity may arise because the energetic requirements of the immune response divert resources that are no longer available for other vital functions. In addition to these resource-based costs, mis-directed or over-reacting immune responses can be particularly harmful for the host. In spite of the potential importance of immunopathology, most studies dealing with the evolution of the immune response have neglected such non resource-based costs. To keep the immune response under control, hosts have evolved regulatory pathways that should be considered when studying the target of the selection pressures acting on immunity. Indeed, variation in regulation may strongly modulate the negative outcome of immune activation, with potentially important fitness consequences. METHODOLOGY/PRINCIPAL FINDINGS: Here, we experimentally assessed the survival costs of reduced immune regulation by inhibiting an anti-inflammatory cytokine (IL-10 with anti-IL-10 receptor antibodies (anti-IL-10R in mice that were either exposed to a mild inflammation or kept as control. The experiment was performed on young (3 months and old (15 months individuals, as to further assess the age-dependent cost of suppressing immune regulation. IL-10 inhibition induced high mortality in old mice exposed to the mild inflammatory insult, whereas no mortality was observed in young mice. However, young mice experienced a transitory lost in body mass when injected with the anti-IL-10R antibodies, showing that the treatment was to a lesser extent also costly for young individuals. CONCLUSIONS: These results suggest a major role of immune regulation that deserves attention when investigating the evolution of immunity, and indicate that the capacity to down-regulate the inflammatory response is crucial for late survival and longevity.

  16. Polarized dependence of nonlinear susceptibility in a single layer graphene system in infrared region

    Energy Technology Data Exchange (ETDEWEB)

    Solookinejad, G., E-mail: ghsolooki@gmail.com

    2016-09-15

    In this study, the linear and nonlinear susceptibility of a single-layer graphene nanostructure driven by a weak probe light and an elliptical polarized coupling field is discussed theoretically. The Landau levels of graphene can be separated in infrared or terahertz regions under the strong magnetic field. Therefore, by using the density matrix formalism in quantum optic, the linear and nonlinear susceptibility of the medium can be derived. It is demonstrated that by adjusting the elliptical parameter, one can manipulate the linear and nonlinear absorption as well as Kerr nonlinearity of the medium. It is realized that the enhanced Kerr nonlinearity can be possible with zero linear absorption and nonlinear amplification at some values of elliptical parameter. Our results may be having potential applications in quantum information science based on Nano scales devices.

  17. Polarization-Dependent Measurements of Molecular Super Rotors with Oriented Angular Momenta

    Science.gov (United States)

    Murray, Matthew J.; Toro, Carlos; Liu, Qingnan; Mullin, Amy S.

    2014-05-01

    Controlling molecular motion would enable manipulation of energy flow between molecules. Here we have used an optical centrifuge to investigate energy transfer between molecular super rotors with oriented angular momenta. The polarizable electron cloud of the molecules interacts with the electric field of linearly polarized light that angularly accelerates over the time of the optical pulse. This process drives molecules into high angular momentum states that are oriented with the optical field and have energies far from equilibrium. High resolution transient IR spectroscopy reveals the dynamics of collisional energy transfer for these super excited rotors. The results of this study leads to a more fundamental understanding of energy balance in non-equilibrium environments and the physical and chemical properties of gases in a new regime of energy states. Results will be presented for several super rotor species including carbon monoxide, carbon dioxide, and acetylene. Polarization-dependent measurements reveal the extent to which the super rotors maintain spatial orientation of high angular momentum states.

  18. Polarization Dependent Bulk-sensitive Valence Band Photoemission Spectroscopy and Density Functional Theory Calculations: Part I. 3d Transition Metals

    Science.gov (United States)

    Ueda, Shigenori; Hamada, Ikutaro

    2017-12-01

    The X-ray polarization dependent valence band HAXPES spectra of 3d transition metals (TMs) of Ti-Zn were measured to investigate the orbital resolved electronic structures by utilizing that the fact the photoionization cross-section of the atomic orbitals strongly depends on the experimental geometry. We have calculated the HAXPES spectra, which correspond to the cross-section weighted densities of states (CSW-DOSs), where the DOSs were obtained by the density functional theory calculations, and we have determined the relative photoionization cross-sections of the 4s and 4p orbitals to the 3d orbital in the 3d TMs. The experimentally obtained bulk-sensitive 3d and 4s DOSs were good agreement with the calculated DOSs in Ti, V, Cr, and Cu. In contrast, the deviations between the experimental and calculated 3d DOSs for Mn, Fe, Co, Ni were found, suggesting that the electron correlation plays an important role in the electronic structures for these materials.

  19. Effects of strong inter-hydrogen bond dynamical couplings in the polarized IR spectra of adipic acid crystals

    Energy Technology Data Exchange (ETDEWEB)

    Flakus, Henryk T., E-mail: flakus@ich.us.edu.pl [Institute of Chemistry, University of Silesia, 9 Szkolna Street, Pl-40-006 Katowice (Poland); Tyl, Aleksandra; Jablonska, Magdalena [Institute of Chemistry, University of Silesia, 9 Szkolna Street, Pl-40-006 Katowice (Poland)

    2009-10-16

    This paper presents the results of the re-investigation of polarized IR spectra of adipic acid and of its d{sub 2}, d{sub 8} and d{sub 10} deuterium derivative crystals. The spectra were measured at 77 K by a transmission method using polarized light for two different crystalline faces. Theoretical analysis concerned linear dichroic effects and H/D isotopic effects observed in the spectra of the hydrogen and deuterium bonds in adipic acid crystals at the frequency ranges of the {nu}{sub O-H} and the {nu}{sub O-D} bands. The two-branch fine structure pattern of the {nu}{sub O-H} and {nu}{sub O-D} bands and the basic linear dichroic effects characterizing them were ascribed to the vibronic mechanism of vibrational dipole selection rule breaking for IR transitions in centrosymmetric hydrogen bond dimers. It was proved that for isotopically diluted crystalline samples of adipic acid, a non-random distribution of protons and deuterons occurs in the dimers (H/D isotopic 'self-organization' effect). This effect results from the dynamical co-operative interactions involving the dimeric hydrogen bonds.

  20. Effects of strong inter-hydrogen bond dynamical couplings in the polarized IR spectra of adipic acid crystals

    Science.gov (United States)

    Flakus, Henryk T.; Tyl, Aleksandra; Jablońska, Magdalena

    2009-10-01

    This paper presents the results of the re-investigation of polarized IR spectra of adipic acid and of its d2, d8 and d10 deuterium derivative crystals. The spectra were measured at 77 K by a transmission method using polarized light for two different crystalline faces. Theoretical analysis concerned linear dichroic effects and H/D isotopic effects observed in the spectra of the hydrogen and deuterium bonds in adipic acid crystals at the frequency ranges of the νO-H and the νO-D bands. The two-branch fine structure pattern of the νO-H and νO-D bands and the basic linear dichroic effects characterizing them were ascribed to the vibronic mechanism of vibrational dipole selection rule breaking for IR transitions in centrosymmetric hydrogen bond dimers. It was proved that for isotopically diluted crystalline samples of adipic acid, a non-random distribution of protons and deuterons occurs in the dimers (H/D isotopic " self-organization" effect). This effect results from the dynamical co-operative interactions involving the dimeric hydrogen bonds.

  1. Polarization-dependent Goos-Hänchen shift at a graded dielectric interface

    Science.gov (United States)

    Löffler, W.; van Exter, M. P.; 't Hooft, G. W.; Eliel, E. R.; Hermans, K.; Broer, D. J.; Woerdman, J. P.

    2010-09-01

    We examine the polarization differential Goos-Hänchen beam shift upon total internal reflection, for a graded-index dielectric interface. We find a generic scaling law where the magnitude of this shift depends solely on the product of wavelength and gradient steepness. The analytic results are extended using transmission matrix calculations in cases where the assumptions made to allow analytical treatment might become questionable. Two important cases in this category are: (i) incident angle close to the critical angle and (ii) gradients with an overall thickness of the order of a wavelength. We demonstrate this effect experimentally using a polymer-blend sample with a gradual refractive-index transition induced by diffusion.

  2. Polarization dependent behavior of CdS around the first and second LO-phonon modes

    Energy Technology Data Exchange (ETDEWEB)

    Frausto-Reyes, C., E-mail: cfraus@cio.mx [Centro de Investigaciones en Optica AC, Unidad Aguascalientes, Prolong., Constitucion 607, Fracc. Reserva Loma Bonita, CP 20200, Apartado Postal 507, Ags. (Mexico); Molina-Contreras, J.R., E-mail: rmolina@correo.ita.mx [Departamento de Ingenieria Electrica y Electronica, Instituto Tecnologico de Aguascalientes, Av. Lopez Mateos 1081 Oriente, Fracc. Bonna Gens, CP 20256, Aguascalientes, Ags. (Mexico); Lopez-Alvarez, Y.F. [Departamento de Ingenieria Electrica y Electronica, Instituto Tecnologico de Aguascalientes, Av. Lopez Mateos 1081 Oriente, Fracc. Bonna Gens, CP 20256, Aguascalientes, Ags. (Mexico); Medel-Ruiz, C.I.; Perez Ladron de Guevara, H. [Universidad de Guadalajara, Centro Universitario de los Lagos, Av. Enrique Diaz de Leon s/n, Fracc. Paseos de la Montana, CP 47460, Lagos de Moreno, Jal. (Mexico); Ortiz-Morales, M. [Centro de Investigaciones en Optica AC, Unidad Aguascalientes, Prolong., Constitucion 607, Fracc. Reserva Loma Bonita, CP 20200, Apartado Postal 507, Ags. (Mexico)

    2010-10-25

    The present work report studies on resonant Raman experimental line shape for CdS around the first and second LO-phonon modes. The application of our method to the study of LO-phonon modes of CdS suggests that the scattered intensity is dominated by the surface and dependent on polarization. Results showed that the Raman spectra for CdS, roughly fall into three groups: a broad line-wing with apparent maxima around 194 cm{sup -1} in the range of 140 and 240 cm{sup -1} which can be ascribed to overtone scattering from acoustic phonons; a band near the 1LO phonon mode which can be attributed to a combination of one-phonon scattering and peak acoustic phonon and finally, a band near the 2LO phonon mode which can be attributed to a combination of two-phonon scattering and peak acoustic phonon.

  3. On the angular dependence and scattering model of polar mesospheric summer echoes at VHF

    Science.gov (United States)

    Sommer, Svenja; Stober, Gunter; Chau, Jorge L.

    2016-01-01

    We present measurements of the angular dependence of polar mesospheric summer echoes (PMSE) with the Middle Atmosphere Alomar Radar System in Northern Norway (69.30° N, 16.04° E). Our results are based on multireceiver and multibeam observations using beam pointing directions with off-zenith angles up to 25° as well as on spatial correlation analysis (SCA) from vertical beam observations. We consider a beam filling effect at the upper and lower boundaries of PMSE in tilted beams, which determines the effective mean angle of arrival. Comparing the average power of the vertical beam to the oblique beams suggests that PMSE are mainly not as aspect sensitive as in contrast to previous studies. However, from SCA, times of enhanced correlation are found, indicating aspect sensitivity or a localized scattering mechanism. Our results suggest that PMSE consist of nonhomogeneous isotropic scattering and previously reported aspect sensitivity values might have been influenced by the inhomogeneous nature of PMSE.

  4. Strong invariance principles for sequential Bahadur--Kiefer and Vervaat error processes of long-range dependent sequences

    OpenAIRE

    Csörgő, Miklós; Szyszkowicz, Barbara; Wang, Lihong

    2006-01-01

    In this paper we study strong approximations (invariance principles) of the sequential uniform and general Bahadur--Kiefer processes of long-range dependent sequences. We also investigate the strong and weak asymptotic behavior of the sequential Vervaat process, that is, the integrated sequential Bahadur--Kiefer process, properly normalized, as well as that of its deviation from its limiting process, the so-called Vervaat error process. It is well known that the Bahadur--Kiefer and the Vervaa...

  5. Strong renormalization scheme dependence in τ-lepton decay: Fact or fiction?

    International Nuclear Information System (INIS)

    Chyla, J.

    1995-01-01

    The question of the renormalization scheme dependence of the τ semileptonic decay rate is examined in response to a recent criticism. Particular attention is payed to a distinction between a consistent quantitative description of this dependence and the actual selection of a subset of ''acceptable'' renormalization schemes. It is pointed out that this criticism is valid only within a particular definition of the ''strength'' of the renormalization scheme dependence and should not discourage further attempts to use the semileptonic τ decay rate for quantitative tests of perturbative QCD

  6. On local strong solutions to the three-dimensional nonhomogeneous incompressible magnetohydrodynamic equations with density-dependent viscosity and vacuum

    Science.gov (United States)

    Song, Sisi

    2018-04-01

    This paper concerns the three-dimensional nonhomogeneous incompressible magnetohydrodynamic equations with density-dependent viscosity and vacuum on Ω \\subset R^3. The domain Ω \\subset R^3 is a general connected smooth one, either bounded or unbounded. In particular, the initial density can have compact support when Ω is unbounded. First, we obtain the local existence and uniqueness of strong solution to the three-dimensional nonhomogeneous incompressible magnetohydrodynamic equations without any compatibility condition assumed on the initial data. Then, we also prove the continuous dependence of strong solution on the initial data under an additional compatibility condition.

  7. STRONG VELOCITY DEPENDENCE OF ELECTRON-CAPTURE IN COLLISIONS BETWEEN ALIGNED NA-ASTERISK(3P) AND HE-2+

    NARCIS (Netherlands)

    SCHLATMANN, AR; HOEKSTRA, R; MORGENSTERN, R; OLSON, RE; PASCALE, J

    1993-01-01

    By analyzing spectra of emitted photons, we have studied state-selective electron capture in collisions of He2+ on aligned Na*(3p) atoms that span the ''velocity-matching'' energy between projectile and target electron. We find a strong dependence of the capture cross sections on the Na*(3p) orbital

  8. A note on the almost sure central limit theorems for the maxima of strongly dependent nonstationary Gaussian vector sequences

    Directory of Open Access Journals (Sweden)

    Xiang Zeng

    2016-06-01

    Full Text Available Abstract We prove some almost sure central limit theorems for the maxima of strongly dependent nonstationary Gaussian vector sequences under some mild conditions. The results extend the ASCLT to nonstationary Gaussian vector sequences and give substantial improvements for the weight sequence obtained by Lin et al. (Comput. Math. Appl. 62(2:635-640, 2011.

  9. Rapid Transition of the Hole Rashba Effect from Strong Field Dependence to Saturation in Semiconductor Nanowires.

    Science.gov (United States)

    Luo, Jun-Wei; Li, Shu-Shen; Zunger, Alex

    2017-09-22

    The electric field manipulation of the Rashba spin-orbit coupling effects provides a route to electrically control spins, constituting the foundation of the field of semiconductor spintronics. In general, the strength of the Rashba effects depends linearly on the applied electric field and is significant only for heavy-atom materials with large intrinsic spin-orbit interaction under high electric fields. Here, we illustrate in 1D semiconductor nanowires an anomalous field dependence of the hole (but not electron) Rashba effect (HRE). (i) At low fields, the strength of the HRE exhibits a steep increase with the field so that even low fields can be used for device switching. (ii) At higher fields, the HRE undergoes a rapid transition to saturation with a giant strength even for light-atom materials such as Si (exceeding 100 meV Å). (iii) The nanowire-size dependence of the saturation HRE is rather weak for light-atom Si, so size fluctuations would have a limited effect; this is a key requirement for scalability of Rashba-field-based spintronic devices. These three features offer Si nanowires as a promising platform for the realization of scalable complementary metal-oxide-semiconductor compatible spintronic devices.

  10. All-optical clocked flip-flops and random access memory cells using the nonlinear polarization rotation effect of low-polarization-dependent semiconductor optical amplifiers

    Science.gov (United States)

    Wang, Yongjun; Liu, Xinyu; Tian, Qinghua; Wang, Lina; Xin, Xiangjun

    2018-03-01

    Basic configurations of various all-optical clocked flip-flops (FFs) and optical random access memory (RAM) based on the nonlinear polarization rotation (NPR) effect of low-polarization-dependent semiconductor optical amplifiers (SOA) are proposed. As the constituent elements, all-optical logic gates and all-optical SR latches are constructed by taking advantage of the SOA's NPR switch. Different all-optical FFs (AOFFs), including SR-, D-, T-, and JK-types as well as an optical RAM cell were obtained by the combination of the proposed all-optical SR latches and logic gates. The effectiveness of the proposed schemes were verified by simulation results and demonstrated by a D-FF and 1-bit RAM cell experimental system. The proposed all-optical clocked FFs and RAM cell are significant to all-optical signal processing.

  11. Dependence of black fragment azimuthal and projected angular distributions on polar angle in silicon-emulsion collisions at 4.5A GeV/c

    International Nuclear Information System (INIS)

    Liu Fuhu; Abd Allah, Nabil N.; Singh, B.K.

    2004-01-01

    The experimental results of dependence of black fragment azimuth (φ) and projected angle (ψ) distributions on polar angle θ in silicon-emulsion collisions at 4.5A GeV/c (the Dubna momentum) are reported. There are two regions of enhancement around φ=±90 deg. for different θ ranges. These enhancements are due to directed (v 1 ) and elliptic (v 2 ) flows. The v 1 and v 2 dependence of values on θ shows that the directed flow is weak and the elliptic flow is strong in these collisions. A multisource ideal gas model is used to describe the experimental results of dependence. The Monte Carlo calculated results are approximately in agreement with the experimental data

  12. Laser based imaging of time depending microscopic scenes with strong light emission

    Science.gov (United States)

    Hahlweg, Cornelius; Wilhelm, Eugen; Rothe, Hendrik

    2011-10-01

    Investigating volume scatterometry methods based on short range LIDAR devices for non-static objects we achieved interesting results aside the intended micro-LIDAR: the high speed camera recording of the illuminated scene of an exploding wire -intended for Doppler LIDAR tests - delivered a very effective method of observing details of objects with extremely strong light emission. As a side effect a schlieren movie is gathered without any special effort. The fact that microscopic features of short time processes with high emission and material flow might be imaged without endangering valuable equipment makes this technique at least as interesting as the intended one. So we decided to present our results - including latest video and photo material - instead of a more theoretical paper on our progress concerning the primary goal.

  13. Temperature dependent polarization reversal mechanism in 0.94(Bi1/2Na1/2)TiO3-0.06Ba(Zr0.02Ti0.98)O3 relaxor ceramics

    Science.gov (United States)

    Glaum, Julia; Simons, Hugh; Hudspeth, Jessica; Acosta, Matias; Daniels, John E.

    2015-12-01

    The temperature at which the electric field induced long-range ordered ferroelectric state undergoes transition into the short-range ordered relaxor state, TF-R, is commonly defined by the onset of strong dispersion of the dielectric permittivity. However, this combined macroscopic property and structural investigation of the polarization reversal process in the prototypical lead-free relaxor 0.94(Bi1/2Na1/2)TiO3-0.06Ba(Zr0.02Ti0.98)O3 reveals that an applied electric field can trigger depolarization and onset of relaxor-like behavior well below TF-R. The polarization reversal process can as such be described as a combination of (1) ferroelectric domain switching and (2) a reversible phase transition between two polar ferroelectric states mediated by a non-polar relaxor state. Furthermore, the threshold fields of the second, mediated polarization reversal mechanism depend strongly on temperature. These results are concomitant with a continuous ferroelectric to relaxor transition occurring over a broad temperature range, during which mixed behavior is observed. The nature of polarization reversal can be illustrated in electric-field-temperature (E-T) diagrams showing the electric field amplitudes associated with different polarization reversal processes. Such diagrams are useful tools for identifying the best operational temperature regimes for a given composition in actuator applications.

  14. On Strong Positive Frequency Dependencies of Quality Factors in Local-Earthquake Seismic Studies

    Science.gov (United States)

    Morozov, Igor B.; Jhajhria, Atul; Deng, Wubing

    2018-03-01

    Many observations of seismic waves from local earthquakes are interpreted in terms of the frequency-dependent quality factor Q( f ) = Q0 f^{η } , where η is often close to or exceeds one. However, such steep positive frequency dependencies of Q require careful analysis with regard to their physical consistency. In particular, the case of η = 1 corresponds to frequency-independent (elastic) amplitude decays with time and consequently requires no Q-type attenuation mechanisms. For η > 1, several problems with physical meanings of such Q-factors occur. First, contrary to the key premise of seismic attenuation, high-frequency parts of the wavefield are enhanced with increasing propagation times relative to the low-frequency ones. Second, such attenuation cannot be implemented by mechanical models of wave-propagating media. Third, with η > 1, the velocity dispersion associated with such Q(f) occurs over unrealistically short frequency range and has an unexpected oscillatory shape. Cases η = 1 and η > 1 are usually attributed to scattering; however, this scattering must exhibit fortuitous tuning into the observation frequency band, which appears unlikely. The reason for the above problems is that the inferred Q values are affected by the conventional single-station measurement procedure. Both parameters Q 0 and are apparent, i.e., dependent on the selected parameterization and inversion method, and they should not be directly attributed to the subsurface. For η ≈ 1, parameter Q 0 actually describes the frequency-independent amplitude decay in access of some assumed geometric spreading t -α , where α is usually taken equal one. The case η > 1 is not allowed physically and could serve as an indicator of problematic interpretations. Although the case 0 < η < 1 is possible, its parameters Q 0 and may also be biased by the measurement procedure. To avoid such difficulties of Q-based approaches, we recommend measuring and interpreting the amplitude-decay rates

  15. Polarization-dependent Character of 1x3 Beam Splitter Using Self-Imaging Phenomena in Air-Slab PhCW

    DEFF Research Database (Denmark)

    Zhang, Min; Malureanu, Radu; Kristensen, Martin

    2010-01-01

    A 1x3 beam splitter in PhCWs using multi-mode interference (MMI) based on self-imaging principle is investigated. The 1x3 splitter is polarization-dependent. The total TE-polarized transmission of the 1x3 splitter is almost equal to the corresponding length of W1 PhCW. The TE-polarized input power...

  16. Polarized angular dependent light scattering from plasmonic nanoparticles: Modeling, measurements, and biomedical applications

    Science.gov (United States)

    Fu, Kun

    Several significant applications have been realized for light scattering in biomedical imaging. In order to improve imaging results with light scattering-based techniques, a variety of nanoparticles have been investigated as contrast agents, including gold nanoshells. As a method for studying the optical properties of plasmonic gold nanoparticles used as contrast agents for molecular imaging, we developed an automated goniometer instrumentation system. This system, which allows us to specifically study polarized angular-dependent light scattering of plasmonic nanoparticles, allowed us to perform a series of theoretical and experimental step-wise studies. The basic optical properties of the following gold nanoparticles were progressively investigated: (1) bare nanoshells at multipolar plasmonic resonances, (2) nanoshells with PEG modifications, (3) surface-textured nanoshells and (4) immunotargeted nanoshells (nanoshell-antibody bioconjugates) for cancer imaging. Based on the results from these studies, a new technique was developed to quantitatively measure the number of immunotargeted nanoparticles that bind to HER2-positive SKBR3 human breast cancer cells. Preliminary studies of determining the minimal incubation time of immunotargeted nanoshells with SKBR3 cells were also carried out to evaluate the potential clinical application of using gold nanoshells intraoperatively. We, therefore, anticipate that our findings will provide the theoretical groundwork required for further studies aimed at optimizing the application of plasmonic nanoparticles in scattering-based optical imaging techniques.

  17. Orientation-dependent chemistry and band-bending of Ti on polar ZnO surfaces.

    Science.gov (United States)

    Borghetti, Patrizia; Mouchaal, Younes; Dai, Zongbei; Cabailh, Gregory; Chenot, Stéphane; Lazzari, Rémi; Jupille, Jacques

    2017-04-19

    Orientation-dependent reactivity and band-bending are evidenced upon Ti deposition (1-10 Å) on polar ZnO(0001)-Zn and ZnO(0001[combining macron])-O surfaces. At the onset of the Ti deposition, a downward band-bending was observed on ZnO(0001[combining macron])-O while no change occurred on ZnO(0001)-Zn. Combining this with the photoemission analysis of the Ti 2p core level and Zn L 3 (L 2 )M 45 M 45 Auger transition, it is established that the Ti/ZnO reaction is of the form Ti + 2ZnO → TiO 2 + 2Zn on ZnO(0001)-Zn and Ti + yZnO → TiZn x O y + (y - x)Zn on ZnO(0001[combining macron])-O. Consistently, upon annealing thicker Ti adlayers, the metallic zinc is removed to leave ZnO(0001)-Zn surfaces covered with a TiO 2 -like phase and ZnO(0001[combining macron])-O surfaces covered with a defined (Ti, Zn, O) compound. Finally, a difference in the activation temperature between the O-terminated (500 K) and Zn-terminated (700 K) surfaces is observed, which is tentatively explained by different electric fields in the space charge layer at ZnO surfaces.

  18. Retrieval of Polar Stratospheric Cloud Microphysical Properties from Lidar Measurements: Dependence on Particle Shape Assumptions

    Science.gov (United States)

    Reichardt, J.; Reichardt, S.; Yang, P.; McGee, T. J.; Bhartia, P. K. (Technical Monitor)

    2001-01-01

    A retrieval algorithm has been developed for the microphysical analysis of polar stratospheric cloud (PSC) optical data obtained using lidar instrumentation. The parameterization scheme of the PSC microphysical properties allows for coexistence of up to three different particle types with size-dependent shapes. The finite difference time domain (FDTD) method has been used to calculate optical properties of particles with maximum dimensions equal to or less than 2 mu m and with shapes that can be considered more representative of PSCs on the scale of individual crystals than the commonly assumed spheroids. Specifically. these are irregular and hexagonal crystals. Selection of the optical parameters that are input to the inversion algorithm is based on a potential data set such as that gathered by two of the lidars on board the NASA DC-8 during the Stratospheric Aerosol and Gas Experiment 0 p (SAGE) Ozone Loss Validation experiment (SOLVE) campaign in winter 1999/2000: the Airborne Raman Ozone and Temperature Lidar (AROTEL) and the NASA Langley Differential Absorption Lidar (DIAL). The 0 microphysical retrieval algorithm has been applied to study how particle shape assumptions affect the inversion of lidar data measured in leewave PSCs. The model simulations show that under the assumption of spheroidal particle shapes, PSC surface and volume density are systematically smaller than the FDTD-based values by, respectively, approximately 10-30% and approximately 5-23%.

  19. Development of an in situ polarization-dependent total-reflection fluorescence XAFS measurement system.

    Science.gov (United States)

    Chun, W J; Tanizawa, Y; Shido, T; Iwasawa, Y; Nomura, M; Asakura, K

    2001-03-01

    An in situ polarization-dependent total-reflection fluorescence X-ray absorption fine structure (PTRF-XAFS) spectroscopy system has been developed, which enables PTRF-XAFS experiments to be performed in three different orientations at various temperatures (273-600 K) and pressures (10(-10) approximately 760 torr). The system consists of a measurement chamber and a preparation chamber. The measurement chamber has a high-precision six-axis goniometer and a multielement solid-state detector. Using a transfer chamber, also operated under ultra-high-vacuum conditions, the sample can be transferred to the measurement chamber from the preparation chamber, which possesses low-energy electron diffraction, Auger electron spectroscopy and X-ray photoelectron spectroscopy facilities, as well as a sputtering gun and an annealing system. The in situ PTRF-EXAFS for Cu species on TiO2 (110) has been measured in three different orientations, revealing anisotropic growth of Cu under the influence of the TiO2 (110) surface.

  20. Polarization modeling and predictions for DKIST part 3: focal ratio and thermal dependencies of spectral polarization fringes and optic retardance

    Science.gov (United States)

    Harrington, David M.; Sueoka, Stacey R.

    2018-01-01

    Data products from high spectral resolution astronomical polarimeters are often limited by fringes. Fringes can skew derived magnetic field properties from spectropolarimetric data. Fringe removal algorithms can also corrupt the data if the fringes and object signals are too similar. For some narrow-band imaging polarimeters, fringes change the calibration retarder properties and dominate the calibration errors. Systems-level engineering tools for polarimetric instrumentation require accurate predictions of fringe amplitudes, periods for transmission, diattenuation, and retardance. The relevant instabilities caused by environmental, thermal, and optical properties can be modeled and mitigation tools developed. We create spectral polarization fringe amplitude and temporal instability predictions by applying the Berreman calculus and simple interferometric calculations to optics in beams of varying F/ number. We then apply the formalism to superachromatic six-crystal retarders in converging beams under beam thermal loading in outdoor environmental conditions for two of the world's largest observatories: the 10-m Keck telescope and the Daniel K. Inouye Solar Telescope (DKIST). DKIST will produce a 300-W optical beam, which has imposed stringent requirements on the large diameter six-crystal retarders, dichroic beamsplitters, and internal optics. DKIST retarders are used in a converging beam with F/ ratios between 8 and 62. The fringe spectral periods, amplitudes, and thermal models of retarder behavior assisted DKIST optical designs and calibration plans with future application to many astronomical spectropolarimeters. The Low Resolution Imaging Spectrograph with polarimetry instrument at Keck also uses six-crystal retarders in a converging F / 13 beam in a Cassegrain focus exposed to summit environmental conditions providing observational verification of our predictions.

  1. Temperature dependence of cross-effect dynamic nuclear polarization in rotating solids

    DEFF Research Database (Denmark)

    Geiger, Michel-Andreas; Orwick-Rydmark, Marcella; Märker, Katharina

    2016-01-01

    Dynamic nuclear polarization exploits electron spin polarization to boost signal-to-noise in magic-angle-spinning (MAS) NMR, creating new opportunities in materials science, structural biology, and metabolomics studies. Since protein NMR spectra recorded under DNP conditions can show improved...

  2. Orientation dependent slip and twinning during compression and tension of strongly textured magnesium AZ31 alloy

    Energy Technology Data Exchange (ETDEWEB)

    Al-Samman, T., E-mail: al-samman@imm.rwth-aachen.de [Institut fuer Metallkunde und Metallphysik, RWTH Aachen, Kopernikusstr. 14, D-52064 Aachen (Germany); Li, X. [Institut fuer Metallkunde und Metallphysik, RWTH Aachen, Kopernikusstr. 14, D-52064 Aachen (Germany); Chowdhury, S. Ghosh [CSIR National Metallurgical Laboratory, MST Division, Jamshedpur 831007 (India)

    2010-06-15

    Over recent years there have been a remarkable number of studies dealing with compression of magnesium. A literature search, however, shows a noticeably less number of papers concerned with tension and a very few papers comparing both modes, systematically, in one study. The current investigation reports the anisotropic deformation behavior and concomitant texture and microstructure evolution investigated in uniaxial tension and compression tests in two sample directions performed on an extruded commercial magnesium alloy AZ31 at different Z conditions. For specimens with the loading direction parallel to the extrusion axis, the tension-compression strength anisotropy was pronounced at high Z conditions. Loading at 45{sup o} from the extrusion axis yielded a tension-compression strength behavior that was close to isotropic. During tensile loading along the extrusion direction the extrusion texture resists twinning and favors prismatic slip (contrary to compression). This renders the shape change maximum in the basal plane and equal to zero along the c-axis, which resulted in the orientation of individual grains remaining virtually intact during all tension tests at different Z conditions. For the other investigated sample direction, straining was accommodated along the c-axis, which was associated with a lattice rotation, and thus, a change of crystal orientation. Uniaxial compression at a low Z condition (400 deg. C/10{sup -4} s{sup -1}) yielded a desired texture degeneration, which was explained on the basis of a more homogeneous partitioning of slip systems that reduces anisotropy and enhanced dynamic recrystallization (DRX), which counteracts the strong deformation texture. The critical strains for the nucleation of DRX in tensiled specimens at the highest investigated Z condition (200 deg. C/10{sup -2} s{sup -1}) were found to range between 4% and 5.6%.

  3. Tunable photonic crystal for THz radiation in layered superconductors: Strong magnetic-field dependence of the transmission coefficient

    International Nuclear Information System (INIS)

    Savel'ev, Sergey; Rakhmanov, A.L.; Nori, Franco

    2006-01-01

    Josephson plasma waves are scattered by the Josephson vortex lattice. This scattering results in a strong dependence, on the in-plane magnetic-field H ab , of the reflection and transmission of THz radiation propagating in layered superconductors. In particular, a tunable band-gap structure (THz photonic crystal) occurs in such a medium. These effects can be used, by varying H ab , for the selective frequency-filtering of THz radiation

  4. Strong dependence of rain-induced lidar depolarization on the illumination angle: experimental evidence and geometrical-optics interpretation.

    Science.gov (United States)

    Roy, G; Bissonnette, L R

    2001-09-20

    Backscatter and depolarization lidar measurements from clouds and precipitation are reported as functions of the elevation angle of the pointing lidar direction. We recorded the data by scanning the lidar beam (Nd:YAG) at a constant angular speed of ~3.5 degrees /s while operating at a repetition rate of 10 Hz. We show that in rain there is an evident and at times spectacular dependence on the elevation angle. That dependence appears to be sensitive to raindrop size. We have developed a three-dimensional polarization-dependent ray-tracing algorithm to calculate the backscatter and the depolarization ratio by large nonspherical droplets. We have applied it to raindrop shapes derived from existing static and dynamic (oscillating) models. We show that many of the observed complex backscatter and depolarization features can be interpreted to a good extent by geometrical optics. These results suggest that there is a definite need for more extensive calculations of the scattering phase matrix elements for large deformed raindrops as functions of the direction of illumination. Obvious applications are retrieval of information on the liquid-solid phase of precipitation and on the size and the vibration state of raindrops.

  5. PROLARM: Cancer risk from medical diagnostic exposures is strongly dependent upon patients' prognosis

    International Nuclear Information System (INIS)

    Eschner, Wolfgang; Schmidt, Matthias; Dietlein, Markus; Schicha, Harald

    2008-01-01

    Full text: Purpose: a) To evaluate the impact of the reduced life expectancy of patients (compared to a non-patient group with same age distribution) on their risk of developing cancer from the diagnostic use of radiation. b) To find an approximation to such reduction in risk which depends only on the patient's age, a, and his life expectancy, but is independent of the choice of values for the baseline risk of cancer incidence, m(a), and the enhanced relative risk ERR(a) from radiation exposure. Method: The lifetime attributable risk LAR (of a radiation-induced malignancy to manifest itself) is a function of age at exposure, e, and given by integrating over attained age, a, the product of ERR(a), baseline cancer risk m(a) and the relative probability of surviving to age a, S'(a,e). We define a 'prognosis-based LAR modifier' (PROLARM) as the ratio of risks for non-patient, LAR(a), and patient, LAR p (a), a dimensionless quantity that gives a measure of reduction of LAR due to the patient's prognosis. With the survival of the patient group, S p ' (a,e), and for any choice of fitted function for ERR(a) like those used in BEIR VII report, PROLARM ≥∫d'(a,e) da/∫S p '(a,e) da, i.e. the ratio of the survival integrals gives a lower (thus conservative) estimate of the reduction in risk. Results: The method was applied to n=4285 patients with metastatic breast cancer for whom survival as a function of age at metastasis was known. Figure shows that LAR is decreased significantly for all ages at exposure. At younger ages, this decrease is more pronounced (PROLARM ≥ 20 for e ≤ 65). Example: using ERR values of BEIR VII, the LAR due to 10 mSv effective dose at age a = 50 would drop from 1.2 E-3 for non-patient to 4.3E-5 for a patient, i.e. by a factor (PROLARM) of 29. Using only survival data, that factor is 27 (but no LAR can be computed). In other words: 10 mSv for a patient correspond risk-wise to 0.4 mSv for non-patient. The method can be applied to any pathology

  6. Energy and polarization dependence of resonant inelastic X-ray scattering in Nd2CuO4

    International Nuclear Information System (INIS)

    Hill, J.P.; Kao, C.C.; Haemaelaeinen, K.

    1998-01-01

    The authors report the energy and polarization dependence of resonant inelastic x-ray scattering from Nd 2 CuO 4 . An energy loss feature at ∼6 eV is observed in the vicinity of the Cu K-edge. Numerical calculations based on the Anderson impurity model identify this as a charge transfer excitation to the anti-bonding state. The incident polarization is shown to select the intermediate states participating in the resonance process. Resonances are observed at 8,990 eV and 9,000 eV with the incident polarization perpendicular and parallel to the CuO planes, respectively. In contrast to the single-site model calculations, no resonances are observed associated with the 1s3d 10 L intermediate states, suggesting non-local effects play a role

  7. Polarity-Dependent Isomerization of an Unsymmetrical Overcrowded Ethylene Promoted by Zwitterionic Contribution in the Twisted Isomer.

    Science.gov (United States)

    Hirao, Yasukazu; Nagamachi, Nobuhiro; Hosoi, Katsuma; Kubo, Takashi

    2018-03-02

    The twisted form of bianthrone is known as a metastable state provided by a photo-induced or thermal-induced isomerization of the folded form, and thus prevents the isolation and the detailed analysis of its electronic structure. In this study, an unsymmetrical bianthrone (2), consisting of the electron-withdrawing anthrone and electron-donating acridane, have been synthesized and shown to exhibit a solvent-polarity-dependent isomerization reaction between the folded and twisted isomers. With increasing the polarity of the solvent, 2 showed an isomerization reaction from the folded form to the twisted form. The stabilization of the twisted isomer in polar solvents can be interpreted as proof of its relatively large zwitterionic character. The DMF solution of 2 displayed paramagnetically-broadened NMR signals from the thermally populated triplet state resulting from rotation of the weakened ethylenic double bond of the twisted isomer. © 2018 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

  8. Polarized neutron reflectometry study on BiFeO3/Co0.9Fe0.1 heterostructures: enhanced magnetization in BiFeO3 and strong magnetic coupling at interface

    Science.gov (United States)

    Wang, Qiang; Gao, Ya; Ramesh, Ramamoorthy; Fitzsimmons, Michael

    2015-03-01

    Polarized neutron reflectometry (PNR) quantified the uncompensated magnetization occurring throughout the thickness of a BiFeO3 (BFO)/ Co0.9Fe0.1 (CoFe) heterostructures. The net uncompensated magnetization (1.0 μB/Fe) within BFO layer is much larger than that which has been theoretically predicted (0.1 μB/Fe) due to the Dzyaloshinskii-Moriya (DM) type interaction. The field dependent study indicates strong interfacial coupling between BFO and CoFe which extends into CoFe layer within about 1 nm interfacial region. The study also suggests the uncompensated magnetization in the BFO layer has relatively small anisotropy.

  9. Polarization-dependent atomic dipole traps behind a circular aperture for neutral-atom quantum computing

    International Nuclear Information System (INIS)

    Gillen-Christandl, Katharina; Copsey, Bert D.

    2011-01-01

    The neutral-atom quantum computing community has successfully implemented almost all necessary steps for constructing a neutral-atom quantum computer. We present computational results of a study aimed at solving the remaining problem of creating a quantum memory with individually addressable sites for quantum computing. The basis of this quantum memory is the diffraction pattern formed by laser light incident on a circular aperture. Very close to the aperture, the diffraction pattern has localized bright and dark spots that can serve as red-detuned or blue-detuned atomic dipole traps. These traps are suitable for quantum computing even for moderate laser powers. In particular, for moderate laser intensities (∼100 W/cm 2 ) and comparatively small detunings (∼1000-10 000 linewidths), trap depths of ∼1 mK and trap frequencies of several to tens of kilohertz are achieved. Our results indicate that these dipole traps can be moved by tilting the incident laser beams without significantly changing the trap properties. We also explored the polarization dependence of these dipole traps. We developed a code that calculates the trapping potential energy for any magnetic substate of any hyperfine ground state of any alkali-metal atom for any laser detuning much smaller than the fine-structure splitting for any given electric field distribution. We describe details of our calculations and include a summary of different notations and conventions for the reduced matrix element and how to convert it to SI units. We applied this code to these traps and found a method for bringing two traps together and apart controllably without expelling the atoms from the trap and without significant tunneling probability between the traps. This approach can be scaled up to a two-dimensional array of many pinholes, forming a quantum memory with single-site addressability, in which pairs of atoms can be brought together and apart for two-qubit gates for quantum computing.

  10. Calcium-dependent protein kinases regulate polarized tip growth in pollen tubes.

    Science.gov (United States)

    Myers, Candace; Romanowsky, Shawn M; Barron, Yoshimi D; Garg, Shilpi; Azuse, Corinn L; Curran, Amy; Davis, Ryan M; Hatton, Jasmine; Harmon, Alice C; Harper, Jeffrey F

    2009-08-01

    Calcium signals are critical for the regulation of polarized growth in many eukaryotic cells, including pollen tubes and neurons. In plants, the regulatory pathways that code and decode Ca(2+) signals are poorly understood. In Arabidopsis thaliana, genetic evidence presented here indicates that pollen tube tip growth involves the redundant activity of two Ca(2+)-dependent protein kinases (CPKs), isoforms CPK17 and -34. Both isoforms appear to target to the plasma membrane, as shown by imaging of CPK17-yellow fluorescent protein (YFP) and CPK34-YFP in growing pollen tubes. Segregation analyses from two independent sets of T-DNA insertion mutants indicate that a double disruption of CPK17 and -34 results in an approximately 350-fold reduction in pollen transmission efficiency. The near sterile phenotype of homozygous double mutants could be rescued through pollen expression of a CPK34-YFP fusion. In contrast, a transgene rescue was blocked by mutations engineered to disrupt the Ca(2+)-activation mechanism of CPK34 (CPK34-YFP-E465A,E500A), providing in vivo evidence linking Ca(2+) activation to a biological function of a CPK. While double mutant pollen tubes displayed normal morphology, relative growth rates for the most rapidly growing tubes were reduced by more than three-fold compared with wild type. In addition, while most mutant tubes appeared to grow far enough to reach ovules, the vast majority (>90%) still failed to locate and fertilize ovules. Together, these results provide genetic evidence that CPKs are essential to pollen fitness, and support a mechanistic model in which CPK17 and -34 transduce Ca(2+) signals to increase the rate of pollen tube tip growth and facilitate a response to tropism cues.

  11. Temperature dependence measurements and structural characterization of trimethyl ammonium ionic liquids with a highly polar solvent.

    Science.gov (United States)

    Attri, Pankaj; Venkatesu, Pannuru; Hofman, T

    2011-08-25

    We report the synthesis and characterization of a series of an ammonium ionic liquids (ILs) containing acetate, dihydrogen phosphate, and hydrogen sulfate anions with a common cation. To characterize the thermophysical properties of these newly synthesized ILs with the highly polar solvent N,N-dimethylformamide (DMF), precise measurements such as densities (ρ) and ultrasonic sound velocities (u) over the whole composition range have been performed at atmospheric pressure and over wide temperature ranges (25-50 °C). The excess molar volume (V(E)) and the deviation in isentropic compressibilities (Δκ(s)) were predicted using these temperature dependence properties as a function of the concentration of ILs. The Redlich-Kister polynomial was used to correlate the results. The ILs investigated in the present study included trimethylammonium acetate [(CH(3))(3)NH][CH(3)COO] (TMAA), trimethylammonium dihydrogen phosphate [(CH(3))(3)NH][H(2)PO(4)] (TMAP), and trimethylammonium hydrogen sulfate [(CH(3))(3)NH][HSO(4)] (TMAS). The intermolecular interactions and structural effects were analyzed on the basis of the measured and the derived properties. In addition, the hydrogen bonding between ILs and DMF has been demonstrated using semiempirical calculations with help of Hyperchem 7. A qualitative analysis of the results is discussed in terms of the ion-dipole, ion-pair interactions, and hydrogen bonding between ILs and DMF molecules and their structural factors. The influence of the anion of the protic IL, namely, acetate (CH(3)COO), dihydrogen phosphate (H(2)PO(4)), and hydrogen sulfate (HSO(4)), on the thermophysical properties is also provided. © 2011 American Chemical Society

  12. Low-frequency (0.7-7.4 mHz geomagnetic field fluctuations at high latitude: frequency dependence of the polarization pattern

    Directory of Open Access Journals (Sweden)

    L. Cafarella

    2001-06-01

    Full Text Available A statistical analysis of the polarization pattern of low-frequency geomagnetic field fluctuations (0.7-7.4 mHz covering the entire 24-h interval was performed at the Antarctic station Terra Nova Bay (80.0°S geomagnetic latitude throughout 1997 and 1998. The results show that the polarization pattern exhibits a frequency dependence, as can be expected from the frequency dependence of the latitude where the coupling between the magnetospheric compressional mode and the field line resonance takes place. The polarization analysis of single pulsation events shows that wave packets with different polarization sense, depending on frequency, can be simultaneously observed.

  13. Angle and Polarization Dependent Fluorescence EXAFS Measurements on Al-doped Single Crystal V_2O3 Above and Below the Transition Temperature

    Science.gov (United States)

    Müller, O.; Pfalzer, P.; Schramme, M.; Urbach, J.-P.; Klemm, M.; Horn, S.; Frenkel, A. I.; Denboer, M. L.

    1998-03-01

    We present angle and polarisation dependent flourescence EXAFS measured on Al-doped single crystal V_2O3 below and above the structural phase transition from monoclinic to trigonal. Strong self-absorption distorted the spectra; this was corrected by using the procedure described by Tröger et al. (L. Tröger, D. Arvantis, K. Baberschke, H. Michaelis, U. Grimm, and E. Zschech, Phys. Rev. B,.46), 3238 (1992), generalized to the Lytle detector employed in our work. The spectra show pronounced dependence on the angle between the threefold symmetry axes and the polarization of the incident photons, making it possible to measure the local atomic distances in different directions. We compare our results with the measurements of Frenkel et al. (A. I. Frenkel, E. A. Stern, and F. A. Chudnovsky, Sol. State Comm.102), 637 (1997) on pure V_2O3 They found that locally the monoclinic distortion persists in the trigonal metallic phase.

  14. Depth enhancement of multi-layer light field display using polarization dependent internal reflection.

    Science.gov (United States)

    Jo, Na-Young; Lim, Hong-Gi; Lee, Sung-Keun; Kim, Yong-Soo; Park, Jae-Hyeung

    2013-12-02

    A technique to enhance the depth range of the multi-layer light field three-dimensional display is proposed. A set of the optical plates are stacked in front of the conventional multi-layer light field display, creating additional internal reflection for one polarization state. By switching between two orthogonal polarization states in synchronization with the displayed three-dimensional images, the depth range of the display can be doubled. The proposed method is verified experimentally, confirming its feasibility.

  15. Laser damage resistance of RbTiOPO(4): evidence of polarization dependent anisotropy.

    Science.gov (United States)

    Wagner, F R; Hildenbrand, A; Natoli, J Y; Commandré, M; Théodore, F; Albrecht, H

    2007-10-17

    Nanosecond-laser induced damage of RbTiOPO(4) crystals (RTP) has been studied at 1064 nm as a function of propagation direction and polarization orientation. A significant difference in the Laser Induced Damage Threshold (LIDT) was observed for x-cut and y-cut crystals in Pockels cell configuration, where the light propagation direction is along the x and y axes of the crystal respectively. In Pockels cell configuration the polarization is oriented at 45? with respect to the z-axis of the crystal. Experiments with the polarization oriented parallel to the principal axes of the crystal pointed out the importance of the polarization direction for the LIDT whereas the propagation direction did not significantly influence the LIDT. Comparison of the experimental data with a simple model reveals the influence of frequency doubling on the LIDT in Pockels cell configuration. In the case of the y-cut Pockels cell, the generation of frequency doubled light causes an LIDT below the LIDT of x and z-polarized light at the fundamental wavelength.

  16. Modulation of human macrophage activity by Ascaris antigens is dependent on macrophage polarization state

    DEFF Research Database (Denmark)

    Almeida, Sara; Nejsum, Peter; Williams, Andrew R.

    2018-01-01

    Parasitic worms (helminths) are known to actively modulate host immune responses and inflammation. The aim of this study was to investigate if adult body fluid (ABF) from the helminth Ascaris suum has immunomodulatory effects on different subtypes of human monocyte-derived macrophages (Mɸ) in vitro....... Mɸs were exposed to A. suum ABF at different stages of their differentiation and/or polarization. Mɸ were first differentiated from monocytes into either uncommitted (M-), classically activated (M(GM-CSF)) or alternatively activated (M(M-CSF)) phenotypes and then stimulated with lipopolysaccharide...... Mɸ to either type 1 or type 2 Mɸ, monocytes were differentiated with human serum into (M-)s and then polarized by IFN-γ/LPS or IL-4 treatment in the presence of ABF. Under these conditions, ABF did not modulate cytokine secretion but did reduce CD80 expression in IFNγ/LPS-polarized cells but not IL-4...

  17. Planck intermediate results. XXII. Frequency dependence of thermal emission from Galactic dust in intensity and polarization

    DEFF Research Database (Denmark)

    Cardoso, J. F.; Delabrouille, J.; Ganga, K.

    2015-01-01

    of the cosmic microwave background. We use a mask that focuses our analysis on the diffuse interstellar medium at intermediate Galactic latitudes. We determine the spectral indices of dust emission in intensity and polarization between 100 and 353 GHz, for each sky patch. Both indices are found to be remarkably......)% from 353 to 70 GHz. We discuss this result within the context of existing dust models. The decrease in p could indicate differences in polarization efficiency among components of interstellar dust (e.g., carbon versus silicate grains). Our observational results provide inputs to quantify and optimize...

  18. Polarity-dependence of the defect formation in c-axis oriented ZnO by the irradiation of an 8 MeV proton beam

    Science.gov (United States)

    Koike, Kazuto; Yano, Mitsuaki; Gonda, Shun-ichi; Uedono, Akira; Ishibashi, Shoji; Kojima, Kazunobu; Chichibu, Shigefusa F.

    2018-04-01

    The polarity dependence of the radiation hardness of single-crystalline ZnO bulk crystals is studied by irradiating the Zn-polar and O-polar c-planes with an 8 MeV proton beam up to the fluence of 4.2 × 1016 p/cm2. To analyze the hardness, radiation-induced defects were evaluated using positron annihilation (PA) analysis, and the recovery by post-annealing was examined using continuous-wave photoluminescence (PL) and time-resolved photoluminescence (TRPL) measurements. It was suggested by the PA and PL analyses that the major defects in both polarities were VZnVO divacancies. While the PA data did not show the clear dependence on the polarity, the PL and TRPL results showed that the Zn-polar c-plane had a little higher radiation tolerance than that of the O-polar c-plane, which was consistent with the result that the increase in the electrical resistance by proton beam irradiation was smaller for the former one. Considering these results in total, the polarity dependence is considered to be not so large, but the Zn-polar c-plane has a little higher tolerance than that of the O-polar one.

  19. "Depend on, Rely on, Count on": Economic Subjectivities Aboard "The Polar Express"

    Science.gov (United States)

    Saltmarsh, Sue

    2009-01-01

    Christmas literature and film produced for children is an important, albeit under-researched, site for the production of cultural values and norms. This paper analyses Chris Van Allsburg's 1985 picture book "The Polar Express", the 2004 Warner Brothers feature film of the same title, the film's official website, and resources for teachers…

  20. Improved geophysical excitations constrained by polar motion observations and GRACE/SLR time-dependent gravity

    Directory of Open Access Journals (Sweden)

    Wei Chen

    2017-11-01

    Full Text Available At seasonal and intraseasonal time scales, polar motions are mainly excited by angular momentum fluctuations due to mass redistributions and relative motions in the atmosphere, oceans, and continental water, snow, and ice, which are usually provided by various global atmospheric, oceanic, and hydrological models (some with meteorological observations assimilated; e.g., NCEP, ECCO, ECMWF, OMCT and LSDM etc.. Unfortunately, these model outputs are far from perfect and have notable discrepancies with respect to polar motion observations, due to non-uniform distributions of meteorological observatories, as well as theoretical approximations and non-global mass conservation in these models. In this study, the LDC (Least Difference Combination method is adopted to obtain some improved atmospheric, oceanic, and hydrological/crospheric angular momentum (AAM, OAM and HAM/CAM, respectively functions and excitation functions (termed as the LDCgsm solutions. Various GRACE (Gravity Recovery and Climate Experiment and SLR (Satellite Laser Ranging geopotential data are adopted to correct the non-global mass conservation problem, while polar motion data are used as general constraints. The LDCgsm solutions can reveal not only periodic fluctuations but also secular trends in AAM, OAM and HAM/CAM, and are in better agreement with polar motion observations, reducing the unexplained excitation to the level of about 5.5 mas (standard derivation value; about 1/5–1/4 of those corresponding to the original model outputs.

  1. Prediction of strong acceleration motion depended on focal mechanism; Shingen mechanism wo koryoshita jishindo yosoku ni tsuite

    Energy Technology Data Exchange (ETDEWEB)

    Kaneda, Y.; Ejiri, J. [Obayashi Corp., Tokyo (Japan)

    1996-10-01

    This paper describes simulation results of strong acceleration motion with varying uncertain fault parameters mainly for a fault model of Hyogo-ken Nanbu earthquake. For the analysis, based on the fault parameters, the strong acceleration motion was simulated using the radiation patterns and the breaking time difference of composite faults as parameters. A statistic waveform composition method was used for the simulation. For the theoretical radiation patterns, directivity was emphasized which depended on the strike of faults, and the maximum acceleration was more than 220 gal. While, for the homogeneous radiation patterns, the maximum accelerations were isotopically distributed around the fault as a center. For variations in the maximum acceleration and the predominant frequency due to the breaking time difference of three faults, the response spectral value of maximum/minimum was about 1.7 times. From the viewpoint of seismic disaster prevention, underground structures including potential faults and non-arranging properties can be grasped using this simulation. Significance of the prediction of strong acceleration motion was also provided through this simulation using uncertain factors, such as breaking time of composite faults, as parameters. 4 refs., 4 figs., 1 tab.

  2. A model of the plasma flow and current in Saturn's polar ionosphere under conditions of strong Dungey cycle driving

    Directory of Open Access Journals (Sweden)

    C. M. Jackman

    2006-05-01

    Full Text Available We propose a simple model of the flow and currents in Saturn's polar ionosphere. This model is motivated by theoretical reasoning, and guided quantitatively by in situ field and flow data from space missions, ground-based IR Doppler measurements, and Hubble Space Telescope images. The flow pattern consists of components which represent (1 plasma sub-corotation in the middle magnetosphere region resulting from plasma pick-up and radial transport from internal sources; (2 the Vasyliunas-cycle of internal plasma mass-loss down the magnetospheric tail at higher latitudes; and (3 the polar Dungey-cycle flow driven by the solar wind interaction. Upstream measurements of the interplanetary magnetic field (IMF indicate the occurrence of both extended low-field rarefaction intervals with essentially negligible Dungey-cycle flow, and few-day high-field compression regions in which the Dungey-cycle voltage peaks at a few hundred kV. Here we model the latter conditions when the Dungey-cycle is active, advancing on previous axi-symmetric models which may be more directly applicable to quiet conditions. For theoretical convenience the overall flow pattern is constructed by adding together two components - a purely rotational flow similar to previous axi-symmetric models, and a sun-aligned twin vortex representing the dawn-dusk asymmetry effects associated with the Vasyliunas-and Dungey-cycle flows. We calculate the horizontal ionospheric current associated with the flow and the field-aligned current from its divergence. These calculations show that a sheet of upward-directed field-aligned current flows at the boundary of open field lines which is strongly modulated in local-time by the Dungey-cycle flows. We then consider implications of the field-aligned current for magnetospheric electron acceleration and aurorae using two plasma source populations (hot outer magnetospheric electrons and cool dense magnetosheath electrons. Both sources display a

  3. SNP rs16969968 as a Strong Predictor of Nicotine Dependence and Lung Cancer Risk in a North Indian Population

    Science.gov (United States)

    Pandey, Namita; Pal, Soumyadip; Sharma, Lokesh Kumar; Guleria, Randeep; Mohan, Anant; Srivastava, Tapasya

    2017-01-01

    Background: The 15q24-25 loci contain genes (CHRNA5 and CHRNA3) encoding nicotinic acetylcholine receptor subunits. We here determined for the first time the association of genetic variants rs16969968 and rs3743074 in CHRNA5 and CHRNA3, respectively, on nicotine dependence and lung cancer risk in a North Indian population by a case-control approach. Methods: Venous blood samples were obtained from 324 participants (108 lung cancer patients and 216 healthy individuals). DNA was extracted and PCR amplified with primers flanking the SNPs rs16969968 and rs3743074. Amplicons were subjected to sequencing and logistic regression was used to analyze association between variables. Results: The risk variant SNP rs16969968 in both heterozygous and homozygous forms appeared to exert a significant effect on nicotine dependence [GA (OR=2.77) and AA (OR=2.53)]. As expected, smoking was strongly associated with lung cancer (OR= 2.62). Risk allele rs16969968 in CHRNA5 also showed a significant association with increased lung cancer risk in our cohort, alone (OR= 4.99) and with smoking as a co-variable (OR= 4.28). Comparison of our analysis with other populations suggested that individuals with rs16969968 risk allele in the Indian population are more susceptible to lung cancer. Conclusion: Overall, the results strongly indicated that, in our cohort North Indian population, the genetic variant rs16969968, but not rs3743074, is significantly associated with both nicotine dependence and increased risk of lung cancer. While the results are significant, there is further need to increase the sample size and improve precision of our risk prediction. PMID:29172281

  4. Impedance of vapor feed direct methanol fuel cells--polarization dependence of elementary processes at the anode

    International Nuclear Information System (INIS)

    Fukunaga, Hiroshi; Ishida, Tomohiro; Teranishi, Nozomu; Arai, Chikao; Yamada, Koichi

    2004-01-01

    Membrane electrode assemblies of direct methanol fuel cells (DMFCs) with different catalyst and ionomer loading were prepared. Anode performance and impedance spectra were measured to clarify the characteristics of vapor feed DMFCs (VF-DMFCs). The impedance spectra were deconvolved into three semi-circles with different time constants, each showing a different dependence on the anodic polarization. The middle-frequency range arc decreased as the anodic polarization increased, indicating that this process represents the oxidation reaction of methanol. The high-frequency range arc showed little dependence on the anodic polarization, but increased with the thickness of the electrode, indicating that this process might be related to proton conduction through the electrode. The low-frequency range arc was observed only when the methanol concentration was low, in contrast to liquid feed DMFCs (LF-DMFCs), for which the removal of the product gas presents a large resistance. A simpler design can therefore be used for a VF-DMFC, giving it an advantage over an LF-DMFC. A decreasing ionomer to catalyst ratio (I/C) caused the interfacial conductivity (σ E ) to increase, but it intensively decreased when I/C was below 0.25. Thus, the connection of the catalysts is important for the anode's performance

  5. Real-time photonic sampling with improved signal-to-noise and distortion ratio using polarization-dependent modulators

    Science.gov (United States)

    Liang, Dong; Zhang, Zhiyao; Liu, Yong; Li, Xiaojun; Jiang, Wei; Tan, Qinggui

    2018-04-01

    A real-time photonic sampling structure with effective nonlinearity suppression and excellent signal-to-noise ratio (SNR) performance is proposed. The key points of this scheme are the polarization-dependent modulators (P-DMZMs) and the sagnac loop structure. Thanks to the polarization sensitive characteristic of P-DMZMs, the differences between transfer functions of the fundamental signal and the distortion become visible. Meanwhile, the selection of specific biases in P-DMZMs is helpful to achieve a preferable linearized performance with a low noise level for real-time photonic sampling. Compared with the quadrature-biased scheme, the proposed scheme is capable of valid nonlinearity suppression and is able to provide a better SNR performance even in a large frequency range. The proposed scheme is proved to be effective and easily implemented for real time photonic applications.

  6. Polarization-dependent transverse-stress sensing based on photonic crystal fiber with gold-coated air-holes

    Science.gov (United States)

    Liu, Hai; Zhu, Chenghao; Wang, Yan; Tan, Ce; Li, Hongwei; Cheng, Deqiang

    2017-05-01

    A transverse-stress sensor with polarization filtering function based on a specially designed photonic crystal fiber (PCF) is proposed. Four ultralarge side-holes are introduced into the cladding layer, and two of them are gold-coated to enhance the stress sensitivity. The finite element method is applied to study the polarization-dependent wavelength-selective sensing characteristics at the optical communication wavelength. Results reveal that the sensor can achieve a high sensitivity in either direction that can be divided into an x-direction component and a y-direction component. Combining the advantages of side-hole structure and surface plasmon resonance technology, the proposed sensor is believed to be an excellent candidate for the transverse-stress measurement.

  7. Polarization dependence of the spin-density-wave excitations in single-domain chromium

    Energy Technology Data Exchange (ETDEWEB)

    Boeni, P. [Paul Scherrer Inst. (PSI), Villigen (Switzerland); Roessli, B. [Institut Max von Laue - Paul Langevin, 75 - Paris (France); Sternlieb, B.J. [Brookhaven (United States); Lorenzo, E. [Centre National de la Recherche Scientifique (CNRS), 38 - Grenoble (France); Werner, S.A. [Missouri (United States)

    1997-09-01

    A polarized neutron scattering experiment has been performed with a single-Q, single domain sample of chromium in a magnetic field of 4 T. It is confirmed that the longitudinal fluctuations are enhanced for small energy transfers and that the spin wave modes with {delta}S parallel to Q and {delta}S perpendicular to Q are similar. (author) 2 figs., 1 tab., 2 refs.

  8. Theoretical Analysis of Thermal Transport in Graphene Supported on Hexagonal Boron Nitride: The Importance of Strong Adhesion Due to π -Bond Polarization

    Science.gov (United States)

    Pak, Alexander J.; Hwang, Gyeong S.

    2016-09-01

    One important attribute of graphene that makes it attractive for high-performance electronics is its inherently large thermal conductivity (κ ) for the purposes of thermal management. Using a combined density-functional theory and classical molecular-dynamics approach, we predict that the κ of graphene supported on hexagonal boron nitride (h -BN) can be as large as 90% of the κ of suspended graphene, in contrast to the significant suppression of κ (more than 70% reduction) on amorphous silica. Interestingly, we find that this enhanced thermal transport is largely attributed to increased lifetimes of the in-plane acoustic phonon modes, which is a notable contrast from the dominant contribution of out-of-plane acoustic modes in suspended graphene. This behavior is possible due to the charge polarization throughout graphene that induces strong interlayer adhesion between graphene and h -BN. These findings highlight the potential benefit of layered dielectric substrates such as h -BN for graphene-based thermal management, in addition to their electronic advantages. Furthermore, our study brings attention to the importance of understanding the interlayer interactions of graphene with layered dielectric materials which may offer an alternative technological platform for substrates in electronics.

  9. In-situ methylation of strongly polar organic acids in natural waters supported by ion-pairing agents for headspace GC-MSD analysis

    Energy Technology Data Exchange (ETDEWEB)

    Neitzel, P.L.; Walther, W. [Dresden University of Technology, Institute for Groundwater Managemant, Dresden (Germany); Nestler, W. [Institute for Technology and Economics, Department of Civil Engineering and Architecture, Dresden (Germany)

    1998-06-01

    Strongly polar organic substances like halogenated acetic acids have been analyzed in surface water and groundwater in the catchment area of the upper Elbe river in Saxony since 1992. Coming directly from anthropogenic sources like industry, agriculture and indirectly by rainfall, their concentrations can increase up to 100 {mu}g/L in the aquatic environment of this catchment area. A new static headspace GC-MSD method without a manual pre-concentration step is presented to analyze the chlorinated acetic acids relevant to the Elbe river as their volatile methyl esters. Using an ion-pairing agent as modifier for the in-situ methylation of the analytes by dimethylsulfate, a minimal detection limit of 1 {mu}g/L can be achieved. Problems like the thermal degradation of chlorinated acetic acids to halogenated hydrocarbons and changing reaction yields during the headspace methylation, could be effectively reduced. The method has been successfully applied to monitoring bank infiltrate, surface water, groundwater and water works pumped raw water according to health provision principles. (orig.) With 3 figs., 2 tabs., 29 refs.

  10. Carrier and polarization dynamics in monolayer MoS2: temperature and power dependence

    Science.gov (United States)

    Urbaszek, Bernhard; Lagarde, D.; Bouet, L.; Amand, T.; Marie, X.; Zhu, C. R.; Liu, B. L.; Tan, P. H.

    2014-03-01

    In monolayer (ML) MoS2 optical transitions across the direct bandgap are governed by chiral selection rules, allowing optical k-valley initialization. Here we present the first time resolved photoluminescence (PL) polarization measurements in MoS2 MLs, providing vital information on the electron valley dynamics. Using quasi-resonant excitation of the A-exciton transitions, we can infer that the PL decays within τ ~= 4ps. The PL polarization of Pc ~ 60 % remains nearly constant in time for experiments from 4K - 300K, a necessary condition for the success of future Valley Hall experiments. τ does not vary significantly over this temperature range. This is surprising when considering the decrease of Pc in continuous wave experiments when going from 4K to 300K reported in the literature. By tuning the laser following the shift of the A-exciton resonance with temperature we are able to recover at 300K ~ 80 % of the polarization observed at 4K. For pulsed laser excitation, we observe a decrease of Pc with increasing laser power at all temperatures.

  11. HbA1c as the diagnostic criterion for diabetes reduces incidence and prevalence of DM2 by 25% but strongly depending on analytical quality

    DEFF Research Database (Denmark)

    Brandslund, Ivan; Nielsen, Aneta Aleksandra; Hyldtoft Petersen, Per

    HbA1c as the diagnostic criterion for diabetes reduces incidence and prevalence of DM2 by 25% but strongly depending on analytical quality......HbA1c as the diagnostic criterion for diabetes reduces incidence and prevalence of DM2 by 25% but strongly depending on analytical quality...

  12. He 2++ molecular ion in a strong time-dependent magnetic field: a current-density functional study.

    Science.gov (United States)

    Vikas

    2011-08-01

    The He 2++ molecular ion exposed to a strong ultrashort time-dependent (TD) magnetic field of the order of 10(9) G is investigated through a quantum fluid dynamics (QFD) and current-density functional theory (CDFT) based approach using vector exchange-correlation (XC) potential and energy density functional that depend not only on the electronic charge-density but also on the current density. The TD-QFD-CDFT computations are performed in a parallel internuclear-axis and magnetic field-axis configuration at the field-free equilibrium internuclear separation R = 1.3 au with the field-strength varying between 0 and 10(11) G. The TD behavior of the exchange- and correlation energy of the He 2++ is analyzed and compared with that obtained using a [B-TD-QFD-density functional theory (DFT)] approach based on the conventional TD-DFT under similar computational constraints but using only scalar XC potential and energy density functional dependent on the electronic charge-density alone. The CDFT based approach yields TD exchange- and correlation energy and TD electronic charge-density significantly different from that obtained using the conventional TD-DFT based approach, particularly, at typical magnetic field strengths and during a typical time period of the TD field. This peculiar behavior of the CDFT-based approach is traced to the TD current-density dependent vector XC potential, which can induce nonadiabatic effects causing retardation of the oscillating electronic charge density. Such dissipative electron dynamics of the He 2++ molecular ion is elucidated by treating electronic charge density as an electron-"fluid" in the terminology of QFD. Copyright © 2011 Wiley Periodicals, Inc.

  13. Noise-induced extinction for a ratio-dependent predator-prey model with strong Allee effect in prey

    Science.gov (United States)

    Mandal, Partha Sarathi

    2018-04-01

    In this paper, we study a stochastically forced ratio-dependent predator-prey model with strong Allee effect in prey population. In the deterministic case, we show that the model exhibits the stable interior equilibrium point or limit cycle corresponding to the co-existence of both species. We investigate a probabilistic mechanism of the noise-induced extinction in a zone of stable interior equilibrium point. Computational methods based on the stochastic sensitivity function technique are applied for the analysis of the dispersion of random states near stable interior equilibrium point. This method allows to construct a confidence domain and estimate the threshold value of the noise intensity for a transition from the coexistence to the extinction.

  14. Size-dependent Young’s modulus in ZnO nanowires with strong surface atomic bonds

    Science.gov (United States)

    Fan, Shiwen; Bi, Sheng; Li, Qikun; Guo, Qinglei; Liu, Junshan; Ouyang, Zhongliang; Jiang, Chengming; Song, Jinhui

    2018-03-01

    The mechanical properties of size-dependent nanowires are important in nano-electro-mechanical systems (NEMSs), and have attracted much research interest. Characterization of the size effect of nanowires in atmosphere directly to broaden their practical application instead of just in high vacuum situations, as reported previously, is desperately needed. In this study, we systematically studied the Young’s modulus of vertical ZnO nanowires in atmosphere. The diameters ranged from 48 nm to 239 nm with a resonance method using non-contact atomic force microscopy. The values of Young’s modulus in atmosphere present extremely strong increasing tendency with decreasing diameter of nanowire due to stronger surface atomic bonds compared with that in vacuum. A core-shell model for nanowires is proposed to explore the Young’s modulus enhancement in atmosphere, which is correlated with atoms of oxygen occurring near the nanowire surface. The modified model is more accurate for analyzing the mechanical behavior of nanowires in atmosphere compared with the model in vacuum. Furthermore, it is possible to use this characterization method to measure the size-related elastic properties of similar wire-sharp nanomaterials in atmosphere and estimate the corresponding mechanical behavior. The study of the size-dependent Young’s modulus in ZnO nanowires in atmosphere will improve the understanding of the mechanical properties of nanomaterials as well as providing guidance for applications in NEMSs, nanogenerators, biosensors and other related areas.

  15. Polarization-dependent NEXAFS study of adsorption of long-chain surfactants on mechanically milled iron powder

    Energy Technology Data Exchange (ETDEWEB)

    Syugaev, A.V., E-mail: syual@mail.ru; Maratkanova, A.N.

    2014-08-15

    Highlights: • Plate-like particles modified with surfactant molecules were obtained under high-energy ball milling. • Adsorption layers were studied with polarization-dependent NEXAFS spectroscopy. • For the first time, arrangement of surfactants molecules on the powdered metal surface has been determined. • Tails of surfactant molecules (C-F/C-H) are shown to be oriented perpendicular to the particle surface. • Arrangement of carboxylate groups on the particle surfaces is discussed. - Abstract: In this work we have demonstrated the possibility of using the polarization-dependent NEXAFS spectra to study the structure of organic layers at the surface of powdered materials with plate-like shaped particles. The polarization dependence of the NEXAFS spectra may be easily obtained by just changing the angle between the X-ray beam direction and the substrate onto which the powder particles are set. For the first time, we have carried out a detailed study of the surfactant layers (n-perfluorononanoic and stearic acid), which are formed at the surface of iron plate-like particles under mechanical milling of iron powder with an addition of corresponding surfactants. The surfactant molecules are predominantly oriented perpendicular to the surface of the mechanically milled particles. Such orientation is similar to the arrangement of the molecules in the layers formed under equilibrium conditions, e.g. deposition from solutions. The changes in the chemical environment occurring in the molecule tails (defluorination or dehydrogenation) under mechanochemical treatment, do not result in a significant change in the molecular orientation and disordering of the adsorbed layer.

  16. Polarization Spectra of Extrasolar Giant Planets

    NARCIS (Netherlands)

    Stam, D.M.

    2004-01-01

    We present simulated spectra of the flux and degree of polarization of starlight that is reflected by extrasolar giant planets (EGPs). In particular the polarization depends strongly on the structure of the planetary atmosphere, and appears to be a valuable tool for the characterization of EGPs.

  17. Strong linkage of polar cod ( Boreogadus saida ) to sea ice algae-produced carbon: Evidence from stomach content, fatty acid and stable isotope analyses

    NARCIS (Netherlands)

    Kohlbach, Doreen; Schaafsma, Fokje L.; Graeve, Martin; Lebreton, Benoit; Lange, Benjamin Allen; David, Carmen; Vortkamp, Martina; Flores, Hauke

    2017-01-01

    The polar cod (Boreogadus saida) is considered an ecological key species, because it reaches high stock biomasses and constitutes an important carbon source for seabirds and marine mammals in high-Arctic ecosystems. Young polar cod (1–2 years) are often associated with the underside of sea ice. To

  18. Polarization-dependent in-line quasi-Michelson interferometer based on PM-PCF reflection.

    Science.gov (United States)

    Du, Yanying; Qiao, Xueguang; Rong, Qiangzhou; Zhang, Jing; Feng, Dingyi; Wang, Ruohui; Sun, Hao; Hu, Manli; Feng, Zhongyao

    2013-05-20

    An in-line fiber quasi-Michelson interferometer (IFQMI) working on reflection is proposed and experimentally demonstrated. The sensing head is fabricated by splicing a section of polarization-maintaining photonic crystal fiber (PM-PCF) with a lead-in single mode fiber (SMF). Some cladding modes are excited into the PM-PCF via the mismatch-core splicing interface between PM-PCF and SMF. Besides, two orthogonal polarized-modes are formed due to the inherent multiholes cladding structure of the PM-PCF. A well-defined interference pattern is obtained as the result of cladding-orthogonal modes interference. The IFQMI with 20 cm long PM-PCF is proposed for strain and torsion measurements. A strain sensitivity of -1.3 pm/με and a torsion sensitivity of -19.17 pm/deg are obtained, respectively. The proposed device with 10 cm long PM-PCF exhibits a considered temperature sensitivity of 9.9 pm/°C. The IFQMI has a compact structure and small size, making it a good candidate for multiparameter measurements.

  19. The phenomenology of optically pumped 13C NMR in diamond at 7.05 T: Room temperature polarization, orientation dependence, and the effect of defect concentration on polarization dynamics

    Science.gov (United States)

    Scott, Eric; Drake, Melanie; Reimer, Jeffrey A.

    2016-03-01

    Room temperature optical illumination of NV- imbibed single crystal diamonds with a 532 nm laser produces 13C polarization enhancements up to 200 times greater than that of the thermal equilibrium value at 7.05 T. We report high field NV- mediated 13C polarization as a function of the number and type (NV- and P1) of defects in commercially available diamonds. Surprisingly, both positive and negative 13C polarizations are observed depending on the orientation of the crystal with respect to the external magnetic field and the electric field vector of the optical illumination. The data reported herein cannot be explained by a previously proposed mechanism.

  20. Fitness Effects of Chlorpyrifos in the Damselfly Enallagma cyathigerum Strongly Depend upon Temperature and Food Level and Can Bridge Metamorphosis.

    Directory of Open Access Journals (Sweden)

    Lizanne Janssens

    Full Text Available Interactions between pollutants and suboptimal environmental conditions can have severe consequences for the toxicity of pollutants, yet are still poorly understood. To identify patterns across environmental conditions and across fitness-related variables we exposed Enallagma cyathigerum damselfly larvae to the pesticide chlorpyrifos at two food levels or at two temperatures and quantified four fitness-related variables (larval survival, development time, mass at emergence and adult cold resistance. Food level and temperature did not affect survival in the absence of the pesticide, yet the pesticide reduced survival only at the high temperature. Animals reacted to the pesticide by accelerating their development but only at the high food level and at the low temperature; at the low food level, however, pesticide exposure resulted in a slower development. Chlorpyrifos exposure resulted in smaller adults except in animals reared at the high food level. Animals reared at the low food level and at the low temperature had a higher cold resistance which was not affected by the pesticide. In summary our study highlight that combined effects of exposure to chlorpyrifos and the two environmental conditions (i were mostly interactive and sometimes even reversed in comparison with the effect of the environmental condition in isolation, (ii strongly differed depending on the fitness-related variable under study, (iii were not always predictable based on the effect of the environmental condition in isolation, and (iv bridged metamorphosis depending on which environmental condition was combined with the pesticide thereby potentially carrying over from aquatic to terrestrial ecosystems. These findings are relevant when extrapolating results of laboratory tests done under ideal environmental conditions to natural communities.

  1. Mycolactone-Dependent Depletion of Endothelial Cell Thrombomodulin Is Strongly Associated with Fibrin Deposition in Buruli Ulcer Lesions.

    Directory of Open Access Journals (Sweden)

    Joy Ogbechi

    2015-07-01

    Full Text Available A well-known histopathological feature of diseased skin in Buruli ulcer (BU is coagulative necrosis caused by the Mycobacterium ulcerans macrolide exotoxin mycolactone. Since the underlying mechanism is not known, we have investigated the effect of mycolactone on endothelial cells, focussing on the expression of surface anticoagulant molecules involved in the protein C anticoagulant pathway. Congenital deficiencies in this natural anticoagulant pathway are known to induce thrombotic complications such as purpura fulimans and spontaneous necrosis. Mycolactone profoundly decreased thrombomodulin (TM expression on the surface of human dermal microvascular endothelial cells (HDMVEC at doses as low as 2 ng/ml and as early as 8 hrs after exposure. TM activates protein C by altering thrombin's substrate specificity, and exposure of HDMVEC to mycolactone for 24 hours resulted in an almost complete loss of the cells' ability to produce activated protein C. Loss of TM was shown to be due to a previously described mechanism involving mycolactone-dependent blockade of Sec61 translocation that results in proteasome-dependent degradation of newly synthesised ER-transiting proteins. Indeed, depletion from cells determined by live-cell imaging of cells stably expressing a recombinant TM-GFP fusion protein occurred at the known turnover rate. In order to determine the relevance of these findings to BU disease, immunohistochemistry of punch biopsies from 40 BU lesions (31 ulcers, nine plaques was performed. TM abundance was profoundly reduced in the subcutis of 78% of biopsies. Furthermore, it was confirmed that fibrin deposition is a common feature of BU lesions, particularly in the necrotic areas. These findings indicate that there is decreased ability to control thrombin generation in BU skin. Mycolactone's effects on normal endothelial cell function, including its ability to activate the protein C anticoagulant pathway are strongly associated with this

  2. Effect of Stabilization Heat Treatment on Time-Dependent Polarization Losses in Sintered Nd-Fe-B Permanent Magnets

    Directory of Open Access Journals (Sweden)

    Tuominen S.

    2013-01-01

    Full Text Available Some companies in the motor and generator industry utilizing sintered NdFeB magnets have adopted pre-ageing heat treatment in order to improve the stability of the magnets. The parameters of this stabilization heat treatment are based mainly on assumptions rather than on any published research results. In this work, the effects of pre-ageing treatment on the time-dependent polarization losses of two different types of commercial sintered NdFeB magnets were studied. The material showing the squarer J(H curve did not benefit from the pre-ageing treatment, since it seems to be stable under a certain critical temperature. In contrast, a stabilizing effect was observed in the material showing rounder J(H curve. After the stabilization heat treatment, the polarization of the magnets was found to be at lower level, but unchanged over a certain period of time. The length of this period depends on the temperature and the duration of the pre-ageing treatment. In addition, our analysis reveals that the stabilization heat treatment performed in an open circuit condition does not stabilize the magnet uniformly.

  3. How to measure a complete set of polarization-dependent differential cross sections in a scattering experiment with aligned reagents?

    Energy Technology Data Exchange (ETDEWEB)

    Wang, Fengyan, E-mail: fengyanwang@fudan.edu.cn, E-mail: kliu@po.iams.sinica.edu.tw [Institute of Atomic and Molecular Sciences, Academia Sinica, P. O. Box 23-166, Taipei 10617, Taiwan (China); Department of Chemistry, Fudan University, Shanghai 200433 (China); Lin, Jui-San; Liu, Kopin, E-mail: fengyanwang@fudan.edu.cn, E-mail: kliu@po.iams.sinica.edu.tw [Institute of Atomic and Molecular Sciences, Academia Sinica, P. O. Box 23-166, Taipei 10617, Taiwan (China)

    2014-02-28

    Polarization-dependent differential cross section (PDDCS) is one of the three-vector correlations (k, k{sup ′}, j) in molecular collisions, which provides the most detailed insights into the steric requirements of chemical reactions, i.e., how the reactivity depends on the polarization of reagents. Only quite recently has such quantity been fully realized experimentally in the study of the reaction of the aligned CHD{sub 3}(v{sub 1} = 1, |jK〉 = |10〉) molecules with Cl({sup 2}P{sub 3/2}) atoms. Theoretically, PDDCS is a relatively new concept; experimental realization of the theoretical construct requires some careful considerations that are not readily available in the literature. Here, we present the “know-how” behind the full PDDCS measurements to fill the gaps and to provide a clear roadmap for future applications. To make the connection apparent between the methodology presented here and the stereodynamics revealed in previous reports, the same Cl + aligned CHD{sub 3} reaction is used for illustration.

  4. Solvent dependency of the UV-Vis spectrum of indenoisoquinolines: role of keto-oxygens as polarity interaction probes.

    Directory of Open Access Journals (Sweden)

    Andrea Coletta

    Full Text Available Indenoisoquinolines are the most promising non-campthotecins topoisomerase IB inhibitors. We present an integrated experimental/computational investigation of the UV-Vis spectra of the IQNs parental compound (NSC314622 and two of its derivatives (NSC724998 and NSC725776 currently undergoing Phase I clinical trials. In all the three compounds a similar dependence of the relative absorption intensities at 270 nm and 290 nm on solvent polarity is found. The keto-oxygens in positions 5 and 11 of the molecular scaffold of the molecule are the principal chromophores involved in this dependence. Protic interactions on these sites are also found to give rise to absorptions at wavelength <250 nm observed in water solution, due to the stabilization of highly polarized tautomers of the molecule. These results suggest that the keto-oxygens are important polarizable groups that can act as useful interactors with the molecular receptor, providing at the same time an useful fingerprint for the monitoring of the drug binding to topoisomerase IB.

  5. How to measure a complete set of polarization-dependent differential cross sections in a scattering experiment with aligned reagents?

    International Nuclear Information System (INIS)

    Wang, Fengyan; Lin, Jui-San; Liu, Kopin

    2014-01-01

    Polarization-dependent differential cross section (PDDCS) is one of the three-vector correlations (k, k ′ , j) in molecular collisions, which provides the most detailed insights into the steric requirements of chemical reactions, i.e., how the reactivity depends on the polarization of reagents. Only quite recently has such quantity been fully realized experimentally in the study of the reaction of the aligned CHD 3 (v 1 = 1, |jK〉 = |10〉) molecules with Cl( 2 P 3/2 ) atoms. Theoretically, PDDCS is a relatively new concept; experimental realization of the theoretical construct requires some careful considerations that are not readily available in the literature. Here, we present the “know-how” behind the full PDDCS measurements to fill the gaps and to provide a clear roadmap for future applications. To make the connection apparent between the methodology presented here and the stereodynamics revealed in previous reports, the same Cl + aligned CHD 3 reaction is used for illustration

  6. Comparing the epidermal growth factor interaction with four different cell lines: intriguing effects imply strong dependency of cellular context.

    Directory of Open Access Journals (Sweden)

    Hanna Björkelund

    Full Text Available The interaction of the epidermal growth factor (EGF with its receptor (EGFR is known to be complex, and the common over-expression of EGF receptor family members in a multitude of tumors makes it important to decipher this interaction and the following signaling pathways. We have investigated the affinity and kinetics of (125I-EGF binding to EGFR in four human tumor cell lines, each using four culturing conditions, in real time by use of LigandTracer®.Highly repeatable and precise measurements show that the overall apparent affinity of the (125I-EGF - EGFR interaction is greatly dependent on cell line at normal culturing conditions, ranging from K(D ≈ 200 pM on SKBR3 cells to K(D≈8 nM on A431 cells. The (125I-EGF - EGFR binding curves (irrespective of cell line have strong signs of multiple simultaneous interactions. Furthermore, for the cell lines A431 and SKOV3, gefitinib treatment increases the (125I-EGF - EGFR affinity, in particular when the cells are starved. The (125I-EGF - EGFR interaction on cell line U343 is sensitive to starvation while as on SKBR3 it is insensitive to gefitinib and starvation.The intriguing pattern of the binding characteristics proves that the cellular context is important when deciphering how EGF interacts with EGFR. From a general perspective, care is advisable when generalizing ligand-receptor interaction results across multiple cell-lines.

  7. Strong Dependence of U.S. Summertime Air Quality on the Decadal Variability of Atlantic Sea Surface Temperatures

    Science.gov (United States)

    Shen, Lu; Mickley, Loretta J.; Leibensperger, Eric M.; Li, Mingwei

    2017-12-01

    We find that summertime air quality in the eastern U.S. displays strong dependence on North Atlantic sea surface temperatures, resulting from large-scale ocean-atmosphere interactions. Using observations, reanalysis data sets, and climate model simulations, we further identify a multidecadal variability in surface air quality driven by the Atlantic Multidecadal Oscillation (AMO). In one-half cycle ( 35 years) of the AMO from cold to warm phase, summertime maximum daily 8 h ozone concentrations increase by 1-4 ppbv and PM2.5 concentrations increase by 0.3-1.0 μg m-3 over much of the east. These air quality changes are related to warmer, drier, and more stagnant weather in the AMO warm phase, together with anomalous circulation patterns at the surface and aloft. If the AMO shifts to the cold phase in future years, it could partly offset the climate penalty on U.S. air quality brought by global warming, an effect which should be considered in long-term air quality planning.

  8. Magnetic-field dependence of strongly anisotropic spin reorientation transition in NdFeO3: a terahertz study.

    Science.gov (United States)

    Jiang, Junjie; Song, Gaibei; Wang, Dongyang; Jin, Zuanming; Tian, Zhen; Lin, Xian; Han, Jiaguang; Ma, Guohong; Cao, Shixun; Cheng, Zhenxiang

    2016-03-23

    One of the biggest challenges in spintronics is finding how to switch the magnetization of a material. One way of the spin switching is the spin reorientation transition (SRT), a switching of macroscopic magnetization rotated by 90°. The macroscopic magnetization in a NdFeO3 single crystal rotates from Γ4 to Γ2 via Γ24 as the temperature is decreased from 170 to 100 K, while it can be switched back to Γ4 again by increasing the temperature. However, the precise roles of the magnetic-field induced SRT are still unclear. By using terahertz time-domain spectroscopy (THz-TDS), here, we show that the magnetic-field induced SRT between Γ4 and Γ2 is strongly anisotropic, depending on the direction of the applied magnetic field. Our experimental results are well interpreted by the anisotropy of rare-earth Nd(3+) ion. Furthermore, we find that the critical magnetic-field required for SRT can be modified by changing the temperature. Our study suggests that the anisotropic SRT in NdFeO3 single crystal provides a platform to facilitate the potential applications in robust spin memory devices.

  9. Polarization-dependent optical characterization of poly(phenylquinoxaline) thin films

    Science.gov (United States)

    Ksianzou, V.; Velagapudi, R. K.; Grimm, B.; Schrader, S.

    2006-09-01

    Linear optical properties of two types of poly(phenylquinoxaline) (PPQ) are studied by multiwavelength prism coupling technique and optical absorption spectroscopy. Surface roughness measurements are done using atomic force microscopy. PPQs form smooth films of high optical quality having refractive indices above 1.7 in the visible and near infrared spectral ranges. Enhanced birefringence of Δn ˜0.04 has been observed in both PPQ films prepared by spin coating. Sellmeier coefficients are derived for the wavelength range starting from 0.532to1.064μm for both TE and TM polarizations. Quantum chemical calculations both on the semiempirical and on the ab initio level are carried out in order to calculate the first-order molecular polarizability tensors of the polymer repeat units. From the obtained tensor elements, theoretical values for both the average refractive indices and the maximum expectable birefringence are calculated. Based on these values a more detailed interpretation of the experimental findings is carried out. The dispersion of refractive index is quantified by the value of Abbe's constant (νd). In our case the value νd≈11 indicates high dispersion in the visible spectral range. The imaginary part k of the complex refractive index n*=n-ik reaches values of k ⩽10-3 in the wavelength range from 0.5to1μm.

  10. A Density-Dependent Switch Drives Stochastic Clustering and Polarization of Signaling Molecules

    Science.gov (United States)

    Jilkine, Alexandra; Angenent, Sigurd B.; Wu, Lani F.; Altschuler, Steven J.

    2011-01-01

    Positive feedback plays a key role in the ability of signaling molecules to form highly localized clusters in the membrane or cytosol of cells. Such clustering can occur in the absence of localizing mechanisms such as pre-existing spatial cues, diffusional barriers, or molecular cross-linking. What prevents positive feedback from amplifying inevitable biological noise when an un-clustered “off” state is desired? And, what limits the spread of clusters when an “on” state is desired? Here, we show that a minimal positive feedback circuit provides the general principle for both suppressing and amplifying noise: below a critical density of signaling molecules, clustering switches off; above this threshold, highly localized clusters are recurrently generated. Clustering occurs only in the stochastic regime, suggesting that finite sizes of molecular populations cannot be ignored in signal transduction networks. The emergence of a dominant cluster for finite numbers of molecules is partly a phenomenon of random sampling, analogous to the fixation or loss of neutral mutations in finite populations. We refer to our model as the “neutral drift polarity model.” Regulating the density of signaling molecules provides a simple mechanism for a positive feedback circuit to robustly switch between clustered and un-clustered states. The intrinsic ability of positive feedback both to create and suppress clustering is a general mechanism that could operate within diverse biological networks to create dynamic spatial organization. PMID:22102805

  11. Polarization dependent Pd deposition structure on LiNbO3 {0001} surface

    Science.gov (United States)

    Kim, Seungchul; Rappe, Andrew M.

    2011-03-01

    We investigate effects of polarization orientation on atomic structure of palladium deposited on lithium niobate (LiNb O3) {0001} surface, using density functional theory (DFT) and kinetic Monte Carlo (kMC) simulations. Adsorption, diffusion, aggregation and clustering process -- include geometries, paths and energies -- of Pd clusters were calculated from DFT simulations. It has been observed that energy barriers of Pd motions on the negatively poled (c-) surface are much larger than those on the positively poled surface (c+), which indicates the Pd motions on the c- surface are much slower than that of c+ surface. We demonstrate, using kMC with kinetic parameters from DFT, very slow motion of Pd on c- surface leads dispersed small clusters or atoms while fast motion on c+ surface leads large clusters, indicating larger Pd-covered area on c- surface than c+ after Pd deposition. This work has been supported by US-DOE (grant DE-FG02-07ER15920), and by AROSR (FA9550-07-1-0397). Computational support was provided by HPCMO of the US-DoD.

  12. A density-dependent switch drives stochastic clustering and polarization of signaling molecules.

    Directory of Open Access Journals (Sweden)

    Alexandra Jilkine

    2011-11-01

    Full Text Available Positive feedback plays a key role in the ability of signaling molecules to form highly localized clusters in the membrane or cytosol of cells. Such clustering can occur in the absence of localizing mechanisms such as pre-existing spatial cues, diffusional barriers, or molecular cross-linking. What prevents positive feedback from amplifying inevitable biological noise when an un-clustered "off" state is desired? And, what limits the spread of clusters when an "on" state is desired? Here, we show that a minimal positive feedback circuit provides the general principle for both suppressing and amplifying noise: below a critical density of signaling molecules, clustering switches off; above this threshold, highly localized clusters are recurrently generated. Clustering occurs only in the stochastic regime, suggesting that finite sizes of molecular populations cannot be ignored in signal transduction networks. The emergence of a dominant cluster for finite numbers of molecules is partly a phenomenon of random sampling, analogous to the fixation or loss of neutral mutations in finite populations. We refer to our model as the "neutral drift polarity model." Regulating the density of signaling molecules provides a simple mechanism for a positive feedback circuit to robustly switch between clustered and un-clustered states. The intrinsic ability of positive feedback both to create and suppress clustering is a general mechanism that could operate within diverse biological networks to create dynamic spatial organization.

  13. About angular dependence of intensity of absent-minded radiation in approach of the strong dissipation of colliding ionic-sound waves

    International Nuclear Information System (INIS)

    Solikhov, D.K.

    2015-01-01

    Present article is devoted to angular dependence of intensity of absent-minded radiation in approach of the strong dissipation of colliding ionic-sound waves. The operation angular dependence of dimensionless of intensity of absent-minded radiation in two-dimensional field of localisation of a wave of a rating in approach of the strong dissipation of passers is ionic-sound waves is viewed. (author)

  14. Constraints on direction-dependent cosmic birefringence from Planck polarization data

    Science.gov (United States)

    Contreras, Dagoberto; Boubel, Paula; Scott, Douglas

    2017-12-01

    Cosmic birefringence is the process that rotates the plane of polarization by an amount, α, as photons propagate through free space. Such an effect arises in parity-violating extensions to the electromagnetic sector, such as the Chern-Simons term common in axion models, quintessence models, or Lorentz-violating extensions to the standard model. Most studies consider the monopole of this rotation, but it is also possible for the effect to have spatial anisotropies. Paying particular attention to large scales, we implement a novel pixel-based method to extract the spherical harmonics for L 30. Our results are consistent with no detection and we set 95 % upper limits on the amplitude of a scale-invariant power spectrum of L(L+1)CL/2π<[2.2 (stat.)±0.7 (syst.)]×10-5=[0.07 (stat.)±0.02 (syst.)] deg2, on par with previous constraints. This implies specific limits on the dipole and quadrupole amplitudes to be √C1/4π lesssim 0.o2 and √C2/4π lesssim 0.o1, at 95 % CL, respectively, improving previous constraints by an order of magnitude. We further constrain a model independent M=0 quadrupole in an arbitrary direction to be α20 = 0.o02 ± 0.o21, with an unconstrained direction. However, we find an excess of dipolar power with an amplitude √3C1/4π = 0.o32±0.o10 (stat.)±0.o08 (syst.)], in the direction (l,b)=(295o,17o)±(22o,17o) (stat.)±(5o,16o) (syst.), larger than 1.4 % of simulations with no birefringence. We attribute part of this signal to the contamination of residual foregrounds not accounted for in our simulations, although this should be further investigated.

  15. Polarization-Dependent Photoinduced Bias-Stress Effect in Single-Crystal Organic Field-Effect Transistors.

    Science.gov (United States)

    Choi, Hyun Ho; Najafov, Hikmet; Kharlamov, Nikolai; Kuznetsov, Denis V; Didenko, Sergei I; Cho, Kilwon; Briseno, Alejandro L; Podzorov, Vitaly

    2017-10-04

    Photoinduced charge transfer between semiconductors and gate dielectrics can occur in organic field-effect transistors (OFETs) operating under illumination, leading to a pronounced bias-stress effect in devices that are normally stable while operating in the dark. Here, we report an observation of a polarization-dependent photoinduced bias-stress effect in two prototypical single-crystal OFETs, based on rubrene and tetraphenylbis(indolo{1,2-a})quinolin. We find that the decay rate of the source-drain current in these OFETs under illumination is a periodic function of the polarization angle of incident photoexcitation with respect to the crystal axes, with a periodicity of π. The angular positions of maxima and minima of the bias-stress rate match those of the optical absorption coefficient of the corresponding crystals. The analysis of the effect shows that it stems from a charge transfer of "hot" holes, photogenerated in the crystal within a very short thermalization length (≪μm) from the semiconductor-dielectric interface. The observed phenomenon is a type of intrinsic structure-property relationship, revealing how molecular packing affects parameter drift in organic transistors under illumination. We also demonstrate that a photoinduced charge transfer in OFETs can be used for recording rewritable accumulation channels with an optically defined geometry and resolution, which can be used in a number of potential applications.

  16. The spin-dependent structure function $g_1(x)$ of the proton from polarized deep-inelastic muon scattering

    CERN Document Server

    Adeva, B; Arvidson, A; Badelek, B; Bardin, G; Baum, G; Berglund, P; Betev, L; Birsa, R; De Botton, N R; Bradamante, Franco; Bravar, A; Bressan, A; Bültmann, S; Burtin, E; Crabb, D; Cranshaw, J; Çuhadar-Dönszelmann, T; Dalla Torre, S; Van Dantzig, R; Derro, B R; Deshpande, A A; Dhawan, S K; Dulya, C M; Eichblatt, S; Fasching, D; Feinstein, F; Fernández, C; Forthmann, S; Frois, Bernard; Gallas, A; Garzón, J A; Gilly, H; Giorgi, M A; Görtz, S; Gracia, G; De Groot, N; Haft, K; Von Harrach, D; Hasegawa, T; Hautle, P; Hayashi, N; Heusch, C A; Horikawa, N; Hughes, V W; Igo, G; Ishimoto, S; Iwata, T; Kabuss, E M; Kageya, T; Karev, A G; Ketel, T; Kiryluk, J; Kiselev, Yu F; Krivokhizhin, V G; Kröger, W; Kukhtin, V V; Kurek, K; Kyynäräinen, J; Lamanna, M; Landgraf, U; Le Goff, J M; Lehár, F; de Lesquen, A; Lichtenstadt, J; Litmaath, M; Magnon, A; Mallot, G K; Marie, F; Martin, A; Martino, J; Matsuda, T; Mayes, B W; McCarthy, J S; Medved, K S; Meyer, W T; Van Middelkoop, G; Miller, D; Miyachi, Y; Mori, K; Moromisato, J H; Nassalski, J P; Naumann, Lutz; Niinikoski, T O; Oberski, J; Ogawa, A; Grosse-Perdekamp, M; Pereira, H; Perrot-Kunne, F; Peshekhonov, V D; Pinsky, L; Platchkov, S K; Pló, M; Pose, D; Postma, H; Pretz, J; Puntaferro, R; Rädel, G; Rijllart, A; Reicherz, G; Rodríguez, M; Rondio, Ewa; Roscherr, B; Sabo, I; Saborido, J; Sandacz, A; Savin, I A; Schiavon, R P; Schiller, A; Sichtermann, E P; Simeoni, F; Smirnov, G I; Staude, A; Steinmetz, A; Stiegler, U; Stuhrmann, H B; Szleper, M; Tessarotto, F; Thers, D; Tlaczala, W; Tripet, A; Ünel, G; Velasco, M; Vogt, J; Voss, Rüdiger; Whitten, C; Windmolders, R; Wislicki, W; Witzmann, A; Ylöstalo, J; Zanetti, A M; Zaremba, K

    1997-01-01

    We present a new measurement of the virtual photon proton asymmetry $A_1^{\\rm p}$ from deep inelastic scattering of polarized muons on polarized protons in the kinematic range $0.0008 1$ GeV$^{2}$. A perturbative QCD evolution in next-to-leading order is used to determine $g_1^{\\rm p}(x)$ at a constant $Q^2$. At $Q^{2} = 10$ GeV$^{2}$ we find, in the measured range, $\\int_{0.003}^{0.7} g_{1}^{\\rm p}(x){\\rm d}x = 0.139 \\pm 0.006~({\\rm stat})\\pm 0.008~({\\rm syst)} \\pm 0.006~({\\rm evol})$. The value of the first moment $\\Gamma_{1}^{\\rm p} = \\int_{0}^{1} g_{1}^{\\rm p}(x){\\rm d}x$ of $g_{1}^{\\rm p}$ depends on the approach used to describe the behaviour of $g_{1}^{\\rm p}$ at low $x$. We find that the Ellis-Jaffe sum rule is violated. With our published result for $\\Gamma_{1}^{\\rm d}$ we confirm the Bjorken sum rule with an accuracy of $\\approx 15\\%$ at the one standard deviation level.

  17. The spin-dependent structure function $g_{1}(x)$ of the deuteron from polarized deep-inelastic muon scattering

    CERN Document Server

    Adams, D; Adeva, B; Akdogan, T; Arik, E; Arvidson, A; Badelek, B; Ballintijn, M K; Bardin, Dimitri Yuri; Bardin, G; Baum, G; Berglund, P; Betev, L; Bird, I G; Birsa, R; Björkholm, P; Bonner, B E; De Botton, N R; Boutemeur, M; Bradamante, Franco; Bravar, A; Bressan, A; Bültmann, S; Burtin, E; Cavata, C; Crabb, D; Cranshaw, J; Çuhadar-Dönszelmann, T; Dalla Torre, S; Van Dantzig, R; Derro, B R; Deshpande, A A; Dhawan, S K; Dulya, C M; Dyring, A; Eichblatt, S; Faivre, Jean-Claude; Fasching, D; Feinstein, F; Fernández, C; Frois, Bernard; Gallas, A; Garzón, J A; Gaussiran, T; Giorgi, M A; von Goeler, E; Gómez, F; Gracia, G; De Groot, N; Grosse-Perdekamp, M; Von Harrach, D; Hasegawa, T; Hautle, P; Hayashi, N; Heusch, C A; Horikawa, N; Hughes, V W; Igo, G; Ishimoto, S; Iwata, T; Kabuss, E M; Kageya, T; Kalinovskaya, L V; Karev, A G; Kessler, H J; Ketel, T; Kiryluk, J; Kishi, A; Kiselev, Yu F; Klostermann, L; Krämer, Dietrich; Krivokhizhin, V G; Kröger, W; Kukhtin, V V; Kurek, K; Kyynäräinen, J; Lamanna, M; Landgraf, U; Le Goff, J M; Lehár, F; de Lesquen, A; Lichtenstadt, J; Lindqvist, T; Litmaath, M; Loewe, M; Magnon, A; Mallot, G K; Marie, F; Martin, A; Martino, J; Matsuda, T; Mayes, B W; McCarthy, J S; Medved, K S; Van Middelkoop, G; Miller, D; Mori, K; Moromisato, J H; Nagaitsev, A P; Nassalski, J P; Naumann, Lutz; Niinikoski, T O; Oberski, J; Ogawa, A; Ozben, C; Parks, D P; Perrot-Kunne, F; Peshekhonov, V D; Piegaia, R; Pinsky, L; Platchkov, S K; Pló, M; Polec, J; Pose, D; Postma, H; Pretz, J; Puntaferro, R; Pussieux, T; Pyrlik, J; Rädel, G; Rijllart, A; Roberts, J B; Rock, S E; Rodríguez, M; Rondio, Ewa; Rosado, A; Sabo, I; Saborido, J; Sandacz, A; Savin, I A; Schiavon, R P; Schüler, K P; Seitz, R; Semertzidis, Y K; Sever, F; Shanahan, P; Sichtermann, E P; Simeoni, F; Smirnov, G I; Staude, A; Steinmetz, A; Steigler, U; Stuhrmann, H B; Szleper, M; Teichert, K M; Tessarotto, F; Tlaczala, W; Trentalange, S; Tripet, A; Ünel, G; Velasco, M; Vogt, J; Voss, Rüdiger; Weinstein, R; Whitten, C; Windmolders, R; Willumeit, R; Wislicki, W; Witzmann, A; Yañez, A; Ylöstalo, J; Zanetti, A M; Zaremba, K; Zhao, J

    1997-01-01

    We present a new measurement of the spin-dependent structure function $g_{1}^{\\rm d}$ of the deuteron from deep inelastic scattering of 190 GeV polarized muons on polarized deuterons. The results are combined with our previous measurements of $g_{1}^{\\rm d}$. A perturbative QCD evolution in next-to-leading order is used to compute $g_{1}^{\\rm d}(x)$ at a constant $Q^{2}$. At $Q^{2} = 10$ GeV$^{2}$, we obtain a first moment $\\Gamma_{1}^{\\rm d} = \\int_{0}^{1} g_{1}^{\\rm d}{\\rm d}x = 0.041 \\pm 0.008$, a flavour-singlet axial charge of the nucleon $a_{0} = 0.30 \\pm 0.08$, and an axial charge of the strange quark $a_{s} = -0.09 \\pm 0.03$. Using our earlier determination of $\\Gamma_{1}^{\\rm p}$, we obtain $\\Gamma_1^{\\rm p} - \\Gamma_1^{\\rm n} = 0.183 \\pm 0.035$ at $Q^2 = 10\\,\\mbox{GeV}^2$. This result is in agreement with the Bjorken sum rule which predicts $\\Gamma_1^{\\rm p} - \\Gamma_1^{\\rm n} = 0.186 \\pm 0.002$ at the same $Q^2$.

  18. Mammalian diaphanous-related formin 1 regulates GSK3β-dependent microtubule dynamics required for T cell migratory polarization.

    Directory of Open Access Journals (Sweden)

    Baoxia Dong

    Full Text Available The mammalian diaphanous-related formin (mDia1, a Rho-regulated cytoskeletal modulator, has been shown to promote T lymphocyte chemotaxis and interaction with antigen presenting cells, but the mechanisms underpinning mDia1 roles in these processes have not been defined. Here we show that mDia1(-/- T cells exhibit impaired lymphocyte function-associated antigen 1 (LFA-1-mediated T cell adhesion, migration and in vivo trafficking. These defects are associated with impaired microtubule (MT polarization and stabilization, altered MT dynamics and reduced peripheral clustering of the MT plus-end-protein, adenomatous polyposis coli (APC in migrating T cells following LFA-1-engagement. Loss of mDia1 also leads to impaired inducible inactivation of the glycogen synthase kinase (GSK 3β as well as hyperphosphorylation and reduced levels of APC in migrating T cells. These findings identify essential roles for the mDia1 formin in modulating GSK3β-dependent MT contributions to induction of T-cell polarity, adhesion and motility.

  19. Vertebrate kidney tubules elongate using a planar cell polarity-dependent, rosette-based mechanism of convergent extension.

    Science.gov (United States)

    Lienkamp, Soeren S; Liu, Kun; Karner, Courtney M; Carroll, Thomas J; Ronneberger, Olaf; Wallingford, John B; Walz, Gerd

    2012-12-01

    Cystic kidney diseases are a global public health burden, affecting over 12 million people. Although much is known about the genetics of kidney development and disease, the cellular mechanisms driving normal kidney tubule elongation remain unclear. Here, we used in vivo imaging to show for the first time that mediolaterally oriented cell intercalation is fundamental to vertebrate kidney morphogenesis. Unexpectedly, we found that kidney tubule elongation is driven in large part by a myosin-dependent, multicellular rosette-based mechanism, previously only described in Drosophila melanogaster. In contrast to findings in Drosophila, however, non-canonical Wnt and planar cell polarity (PCP) signaling is required to control rosette topology and orientation during vertebrate kidney tubule elongation. These data resolve long-standing questions concerning the role of PCP signaling in the developing kidney and, moreover, establish rosette-based intercalation as a deeply conserved cellular engine for epithelial morphogenesis.

  20. Direct transverse load profile determination using the polarization-dependent loss spectral response of a chirped fiber Bragg grating.

    Science.gov (United States)

    Descamps, Frédéric; Bette, Sébastien; Kinet, Damien; Caucheteur, Christophe

    2016-06-01

    The determination of stress profiles created by transverse loads was proved to be important in different domains, such as structural health monitoring and biomechanics, and, more specifically, in the prostheses domain. In this paper, we report an original method to estimate the transverse load profile from the polarization-dependent loss (PDL) spectrum of a chirped fiber Bragg grating (CFBG). This method makes use of the relationship between the integration of the PDL of a CFBG, and the force profile has the advantage of not requiring any iterative method to estimate the transverse load profile. The relationship linking the integration of the PDL and the force profile is demonstrated using an analytical approximation of the transmission spectrum of CFBGs. The validity of this method for the determination of non-uniform load profiles is then shown using a numerical analysis. An experimental demonstration is finally reported using a 48 mm-long CFBG subject to different step transverse load profiles.

  1. A note on polarized light from magnetars

    Energy Technology Data Exchange (ETDEWEB)

    Capparelli, L.M.; Damiano, A.; Polosa, A.D. [Sapienza Universita di Roma, Dipartimento di Fisica, Rome (Italy); INFN, Rome (Italy); Maiani, L. [CERN, Theory Department, Geneva (Switzerland)

    2017-11-15

    In a recent paper it is claimed that vacuum birefringence has been experimentally observed for the first time by measuring the degree of polarization of visible light from a magnetar candidate, a neutron star with a magnetic field presumably as large as B ∝ 10{sup 13} G. The role of such a strong magnetic field is twofold. First, the surface of the star emits, at each point, polarized light with linear polarization correlated with the orientation of the magnetic field. Depending on the relative orientation of the magnetic axis of the star with the direction to the distant observer, a certain degree of polarization should be visible. Second, the strong magnetic field in the vacuum surrounding the star could enhance the effective degree of polarization observed: vacuum birefringence. We compare experimental data and theoretical expectations concluding that the conditions to support a claim of strong evidence of vacuum birefringence effects are not met. (orig.)

  2. Temperature Dependence of the Inhibition of Positronium by Chlorine- Substituted Hydrocarbons in Non-Polar Liquids

    DEFF Research Database (Denmark)

    Wikander, G.; Mogensen, O.E.; Pedersen, Niels Jørgen

    1984-01-01

    Positron annihilation lifetime spectra were measured for solutions of 1,2,3,5-C6H2Cl4 in hexane, toluene, m-xylene and mesitylene, CCl4 in hexane and toluene, and C2HCl3 in n-hexane for concentrations below 1 M and at various temperatures between −30°C and 67°C. The Ps inhibition by C6H2Cl4...... was roughly 14 times stronger at −30°C than at 67°C in toluene, m-xylene, and mesitylene, while that of CCl4 displayed hardly any temperature dependence in hexane and toluene. Previously, the Ps inhibition by C6H2Cl4 in various liquids at 20°C was explained by a competition between electron pick off...

  3. Scattering of polarized 7Li by 120Sn and projectile-target spin-dependent interactions

    International Nuclear Information System (INIS)

    Sakuragi, Y.; Yahiro, M.; Kamimura, M.; Tanifuji, M.

    1986-07-01

    Scattering of 7 Li by 120 Sn targets at E lab = 44 MeV is investigated in the coupled-channel frame by taking account of the projectile virtual excitations to the lowest three excited states. Calculations are performed by the cluster-folding (CF) interactions and the double-folding (DF) one. Both interactions reproduce very well the expeimental data on the cross section, the vector analyzing power, the second-rank tensor ones and the third-rank tensor one in elastic and projectile inelastic scattering, although some differences are found between the CF results and the DF ones. In the calculation, the virtual excitations of the projectile are important for most of the analyzing powers and the spin-orbit interaction is indispensable for the vector analyzing power. These features are in contrast to those in 7 Li - 58 Ni scattering at 20 MeV and are interpreted as over-Coulomb-barrier effects. The scattering amplitudes and the analyzing powers are investigated by the invariant amplitude method, which provides a key connecting the spin-dependent interactions to the analyzing powers. The method proposes an important relationship between the tensor analyzing powers, which is useful in analyses of both theoretical and experimental results. Finally, it is found that in the elastic scattering the second-rank tensor analyzing powers are proportional to the strength of the second-rank tensor interaction and the vector and third-rank tensor analyzing powers to the square or cube of the strength of this interaction, while in the inelastic scattering the cross section is proportional to the square of the strength of the tensor interaction, other quantities being weakly dependent on the strength. (author)

  4. DISTRIBUTION AND MIGRATION OF POLAR BEARS, PACIFIC WALRUSES AND GRAY WHALES DEPENDING ON ICE CONDITIONS IN THE RUSSIAN ARCTIC (17th Symposium on Polar Biology)

    OpenAIRE

    Stanislav, BELIKOV; Andrei, BOLTUNOV; Yuri, GORBUNOV

    1996-01-01

    This report presents a review of available data concerning the influence of ice cover on distribution, density and migration of three species of marine mammals inhabiting the Russian Arctic. Association of marine mammals with ice cover is as follows: (1) the polar bear is distributed in ice zone in the whole year, (2) the walrus is associated with the ice zone only in summer, and (3) the gray whale inhabits the southern area of the ice zone.

  5. Extending the strong-field approximation of high-order harmonic generation to polar molecules: gating mechanisms and extension of the harmonic cutoff

    DEFF Research Database (Denmark)

    Etches, Adam; Madsen, Lars Bojer

    2010-01-01

    Polar molecules such as CO are interesting target systems for high-order harmonic generation (HHG) as they can be oriented with current laser techniques, thus allowing the study of systems without inversion symmetry. However, the asymmetry of the molecule also means that the molecular orbitals...... (enhanced) every other half-cycle. We show that the Stark shift weakens the strength of system-induced gating and also determines the relative contribution from opposite orientations in field-induced gating. Finally, we propose a novel scheme for extending the high-order harmonic cutoff by letting the two...

  6. PH-DEPENDENT PROTON PERMEABILITY OF THE PLASMA-MEMBRANE IN A REGULATING MECHANISM OF POLAR TRANSPORT THROUGH THE SUBMERGED LEAVES OF POTAMOGETON-LUCENS

    NARCIS (Netherlands)

    MIEDEMA, H; PRINS, HBA

    Recently it has been hypothesized that light-induced polarity in leaves of the submerged angiosperms Potamogeton and Elodea results in part from a pH-dependent change in the permeability of the plasma membrane for protons. It is assumed that the proton permeability increases at high pH. In this

  7. Investigation of photon detection probability dependence of SPADnet-I digital photon counter as a function of angle of incidence, wavelength and polarization

    Energy Technology Data Exchange (ETDEWEB)

    Játékos, Balázs, E-mail: jatekosb@eik.bme.hu; Ujhelyi, Ferenc; Lőrincz, Emőke; Erdei, Gábor

    2015-01-01

    SPADnet-I is a prototype, fully digital, high spatial and temporal resolution silicon photon counter, based on standard CMOS imaging technology, developed by the SPADnet consortium. Being a novel device, the exact dependence of photon detection probability (PDP) of SPADnet-I was not known as a function of angle of incidence, wavelength and polarization of the incident light. Our targeted application area of this sensor is next generation PET detector modules, where they will be used along with LYSO:Ce scintillators. Hence, we performed an extended investigation of PDP in a wide range of angle of incidence (0° to 80°), concentrating onto a 60 nm broad wavelength interval around the characteristic emission peak (λ=420 nm) of the scintillator. In the case where the sensor was optically coupled to a scintillator, our experiments showed a notable dependence of PDP on angle, polarization and wavelength. The sensor has an average PDP of approximately 30% from 0° to 60° angle of incidence, where it starts to drop rapidly. The PDP turned out not to be polarization dependent below 30°. If the sensor is used without a scintillator (i.e. the light source is in air), the polarization dependence is much less expressed, it begins only from 50°.

  8. On the model dependence of the determination of the strong coupling constant in second order QCD from e+e--annihilation into hadrons

    International Nuclear Information System (INIS)

    Achterberg, O.; D'Agostini, G.; Apel, W.D.; Engler, J.; Fluegge, G.; Forstbauer, B.; Fries, D.C.; Fues, W.; Gamerdinger, K.; Henkes, T.; Hopp, G.; Krueger, M.; Kuester, H.; Mueller, H.; Randoll, H.; Schmidt, G.; Schneider, H.; Boer, W. de; Buschhorn, G.; Grindhammer, G.; Grosse-Wiesmann, P.; Gunderson, B.; Kiesling, C.; Kotthaus, R.; Kruse, U.; Lierl, H.; Lueers, D.; Oberlack, H.; Schacht, P.; Bonneaud, G.; Colas, P.; Cordier, A.; Davier, M.; Fournier, D.; Grivaz, J.F.; Haissinski, J.; Journe, V.; Laplanche, F.; Le Diberder, F.; Mallik, U.; Ros, E.; Veillet, J.J.; Behrend, H.J.; Fenner, H.; Schachter, M.J.; Schroeder, V.; Sindt, H.

    1983-12-01

    Hadronic events obtained with the CELLO detector at PETRA are compared with second order QCD predictions using different models for the fragmentation of quarks and gluons into hadrons. We find that the model dependence in the determination of the strong coupling constant persists when going from first to second order QCD calculations. (orig.)

  9. miRNA independent hepacivirus variants suggest a strong evolutionary pressure to maintain miR-122 dependence

    DEFF Research Database (Denmark)

    Yu, Yingpu; Scheel, Troels K.H.; Luna, Joseph M.

    2017-01-01

    Hepatitis C virus (HCV) requires the liver specific micro-RNA (miRNA), miR-122, to replicate. This was considered unique among RNA viruses until recent discoveries of HCV-related hepaciviruses prompting the question of a more general miR-122 dependence. Among hepaciviruses, the closest known HCV...... generated infectious NPHV/HCV chimeric viruses with the 5’ end of NPHV replacing orthologous HCV sequences. These chimeras were viable even in cells lacking miR-122, although miR-122 presence enhanced virus production. No other miRNAs bound this region. By random mutagenesis, we isolated HCV variants...... partially dependent on miR-122 as well as robustly replicating NPHV/HCV variants completely independent of any miRNAs. These miRNA independent variants even replicate and produce infectious particles in non-hepatic cells after exogenous delivery of apolipoprotein E (ApoE). Our findings suggest that miR-122...

  10. Unitary Dynamics of Strongly Interacting Bose Gases with the Time-Dependent Variational Monte Carlo Method in Continuous Space

    Science.gov (United States)

    Carleo, Giuseppe; Cevolani, Lorenzo; Sanchez-Palencia, Laurent; Holzmann, Markus

    2017-07-01

    We introduce the time-dependent variational Monte Carlo method for continuous-space Bose gases. Our approach is based on the systematic expansion of the many-body wave function in terms of multibody correlations and is essentially exact up to adaptive truncation. The method is benchmarked by comparison to an exact Bethe ansatz or existing numerical results for the integrable Lieb-Liniger model. We first show that the many-body wave function achieves high precision for ground-state properties, including energy and first-order as well as second-order correlation functions. Then, we study the out-of-equilibrium, unitary dynamics induced by a quantum quench in the interaction strength. Our time-dependent variational Monte Carlo results are benchmarked by comparison to exact Bethe ansatz results available for a small number of particles, and are also compared to quench action results available for noninteracting initial states. Moreover, our approach allows us to study large particle numbers and general quench protocols, previously inaccessible beyond the mean-field level. Our results suggest that it is possible to find correlated initial states for which the long-term dynamics of local density fluctuations is close to the predictions of a simple Boltzmann ensemble.

  11. The extent to which ATP demand controls the glycolytic flux depends strongly on the organism and conditions for growth

    DEFF Research Database (Denmark)

    Købmann, Brian Jensen; Westerhoff, H.V.; Snoep, J.L.

    2002-01-01

    Using molecular genetics we have introduced uncoupled ATPase activity in two different bacterial species, Escherichia coli and Lactococcus lactis, and determined the elasticities of the growth rate and glycolytic flux towards the intracellular [ATP]/[ADP] ratio. During balanced growth in batch...... cultures of E. coli the ATP demand was found to have almost full control on the glycolytic flux (FCC=0.96) and the flux could be stimulated by 70%. In contrast to this, in L. lactis the control by ATP demand on the glycolytic flux was close to zero. However, when we used non-growing cells of L. lactis...... (which have a low glycolytic flux) the ATP demand had a high flux control and the flux could be stimulated more than two fold. We suggest that the extent to which ATP demand controls the glycolytic flux depends on how much excess capacity of glycolysis is present in the cells....

  12. Long-periodic strong radar echoes in the summer polar D region correlated with oscillations of high-speed solar wind streams

    Science.gov (United States)

    Lee, Young-Sook; Kirkwood, Sheila; Shepherd, Gordon G.; Kwak, Young-Sil; Kim, Kyung-Chan

    2013-08-01

    We report long-periodic oscillations of polar mesospheric summer echoes (PMSEs) correlated with high-speed solar wind streams (HSSs) as observed between 1 June and 8 August in the solar minimum years 2006 and 2008. PMSEs (80-90 km altitudes) were observed by 52 MHz VHF radar measurements at Esrange, Sweden (67.8°N, 20.4°E). Correlations between PMSE volume reflectivity/counts, HSSs, and AE index are primarily found at 7-day, 9-day, and 13-day periodicities as well as 9-day and 13.5-day periodicities in 2006 and 2008, respectively. The observations show that the effects of HSSs appear in PMSEs. During corotating interaction region (CIR)-induced HSSs, the long-lasting enhancement of PMSEs, geomagnetic disturbances, and D-region ionization suggests that a favorable condition in generating PMSEs can be provided by the precipitating energetic electrons (>30 keV), which are frequently multiplied in the magnetosphere during HSSs.

  13. Laser polarization dependence of proton emission from a thin foil target irradiated by a 70 fs, intense laser pulse

    International Nuclear Information System (INIS)

    Fukumi, A.; Nishiuchi, M.; Daido, H.; Li, Z.; Sagisaka, A.; Ogura, K.; Orimo, S.; Kado, M.; Hayashi, Y.; Mori, M.; Bulanov, S.V.; Esirkepov, T.; Nemoto, K.; Oishi, Y.; Nayuki, T.; Fujii, T.; Noda, A.; Nakamura, S.

    2005-01-01

    A study of proton emission from a 3-μm-thick Ta foil target irradiated by p-, s-, and circularly polarized laser pulses with respect to the target plane has been carried out. Protons with energies up to 880 keV were observed in the target normal direction under the irradiation by the p-polarized laser pulse, which yielded the highest efficiency for proton emission. In contrast, s- and circularly polarized laser pulses gave the maximum energies of 610 and 680 keV, respectively. The difference in the maximum energy between the p- and s-polarized cases was associated with the difference between the sheath fields estimated from electron spectra

  14. SU-C-304-07: Are Small Field Detector Correction Factors Strongly Dependent On Machine-Specific Characteristics?

    International Nuclear Information System (INIS)

    Mathew, D; Tanny, S; Parsai, E; Sperling, N

    2015-01-01

    Purpose: The current small field dosimetry formalism utilizes quality correction factors to compensate for the difference in detector response relative to dose deposited in water. The correction factors are defined on a machine-specific basis for each beam quality and detector combination. Some research has suggested that the correction factors may only be weakly dependent on machine-to-machine variations, allowing for determinations of class-specific correction factors for various accelerator models. This research examines the differences in small field correction factors for three detectors across two Varian Truebeam accelerators to determine the correction factor dependence on machine-specific characteristics. Methods: Output factors were measured on two Varian Truebeam accelerators for equivalently tuned 6 MV and 6 FFF beams. Measurements were obtained using a commercial plastic scintillation detector (PSD), two ion chambers, and a diode detector. Measurements were made at a depth of 10 cm with an SSD of 100 cm for jaw-defined field sizes ranging from 3×3 cm 2 to 0.6×0.6 cm 2 , normalized to values at 5×5cm 2 . Correction factors for each field on each machine were calculated as the ratio of the detector response to the PSD response. Percent change of correction factors for the chambers are presented relative to the primary machine. Results: The Exradin A26 demonstrates a difference of 9% for 6×6mm 2 fields in both the 6FFF and 6MV beams. The A16 chamber demonstrates a 5%, and 3% difference in 6FFF and 6MV fields at the same field size respectively. The Edge diode exhibits less than 1.5% difference across both evaluated energies. Field sizes larger than 1.4×1.4cm2 demonstrated less than 1% difference for all detectors. Conclusion: Preliminary results suggest that class-specific correction may not be appropriate for micro-ionization chamber. For diode systems, the correction factor was substantially similar and may be useful for class-specific reference

  15. Low-frequency ac electroporation shows strong frequency dependence and yields comparable transfection results to dc electroporation.

    Science.gov (United States)

    Zhan, Yihong; Cao, Zhenning; Bao, Ning; Li, Jianbo; Wang, Jun; Geng, Tao; Lin, Hao; Lu, Chang

    2012-06-28

    Conventional electroporation has been conducted by employing short direct current (dc) pulses for delivery of macromolecules such as DNA into cells. The use of alternating current (ac) field for electroporation has mostly been explored in the frequency range of 10kHz-1MHz. Based on Schwan equation, it was thought that with low ac frequencies (10Hz-10kHz), the transmembrane potential does not vary with the frequency. In this report, we utilized a flow-through electroporation technique that employed continuous 10Hz-10kHz ac field (based on either sine waves or square waves) for electroporation of cells with defined duration and intensity. Our results reveal that electropermeabilization becomes weaker with increased frequency in this range. In contrast, transfection efficiency with DNA reaches its maximum at medium frequencies (100-1000Hz) in the range. We postulate that the relationship between the transfection efficiency and the ac frequency is determined by combined effects from electrophoretic movement of DNA in the ac field, dependence of the DNA/membrane interaction on the ac frequency, and variation of transfection under different electropermeabilization intensities. The fact that ac electroporation in this frequency range yields high efficiency for transfection (up to ~71% for Chinese hamster ovary cells) and permeabilization suggests its potential for gene delivery. Copyright © 2012 Elsevier B.V. All rights reserved.

  16. Quark matter and quark stars in strong magnetic fields at finite temperature within the confined-isospin-density-dependent mass model

    Science.gov (United States)

    Chu, Peng-Cheng; Li, Xiao-Hua; Ma, Hong-Yang; Wang, Bin; Dong, Yu-Min; Zhang, Xiao-Min

    2018-03-01

    We study the properties of strange quark matter (SQM) and quark stars (QSs) in strong magnetic fields within the extended confined isospin-density-dependent mass (CIDDM) model including the temperature dependence of the equivalent mass for quarks. The quark symmetry energy, quark symmetry free energy, and the equation of state (EOS) of SQM in constant magnetic fields at finite temperature are investigated, and it is found that including the temperature dependence in CIDDM model and considering strong magnetic fields can both significantly influence the properties of the SQM and the maximum mass of quark stars. Using the density-dependent magnetic field and assuming two extreme cases for the magnetic field orientation in QSs (the radial orientation in which the local magnetic fields are along the radial direction and the transverse orientation in which the local magnetic fields are randomly oriented but perpendicular to the radial orientation), we analyze the mass-radius relations for different stages of the protoquark stars (PQSs) along the star evolution. Our results indicate that the maximum mass of magnetized PQSs may depend on not only the strength distribution and the orientation of the magnetic fields inside the PQSs, but also the heating process and the cooling process in the star evolution.

  17. The formation of quiescent glomerular endothelial cell monolayer in vitro is strongly dependent on the choice of extracellular matrix coating

    Energy Technology Data Exchange (ETDEWEB)

    Pajęcka, Kamilla, E-mail: kpaj@novonordisk.com [Global Research, Novo Nordisk A/S, Måløv (Denmark); Department of Endocrinology and Internal Medicine, Aarhus University Hospital, Aarhus (Denmark); Nielsen, Malik Nygaard [Global Research, Novo Nordisk A/S, Måløv (Denmark); Hansen, Troels Krarup [Department of Endocrinology and Internal Medicine, Aarhus University Hospital, Aarhus (Denmark); Williams, Julie M. [Global Research, Novo Nordisk A/S, Måløv (Denmark)

    2017-04-01

    Background and aims: Nephropathy involves pathophysiological changes to the glomerulus. The primary glomerular endothelial cells (GEnCs) have emerged as an important tool for studying glomerulosclerotic mechanisms and in the screening process for drug-candidates. The success of the studies is dependent on the quality of the cell model. Therefore, we set out to establish an easy, reproducible model of the quiescent endothelial monolayer with the use of commercially available extracellular matrices (ECMs). Methods: Primary hGEnCs were seeded on various ECMs. Cell adhesion was monitored by an impedance sensing system. The localization of junctional proteins was assessed by immunofluorescence and the barrier function by passage of fluorescent dextrans and magnitude of VEGF response. Results: All ECM matrices except recombinant human laminin 111 (rhLN111) supported comparable cell proliferation. Culturing hGEnCs on rhLN521, rhLN511 or fibronectin resulted in a physiologically relevant barrier to 70 kDa dextrans which was 82% tighter than that formed on collagen type IV. Furthermore, only hGEnCs cultured on rhLN521 or rhLN511 showed plasma-membrane localized zonula occludens-1 and vascular endothelial cadherin indicative of proper tight and adherens junctions (AJ). Conclusion: We recommend culturing hGEnCs on the mature glomerular basement membrane laminin - rhLN521 – which, as the only commercially available ECM, promotes all of the characteristics of the quiescent hGEnC monolayer: cobblestone morphology, well-defined AJs and physiological perm-selectivity. - Highlights: • rhLN521, rhLN511 and hFN assure physiologically relevant permeability. • rhLN521 and rhLN511 ensure best cell morphology and adherens junction formation. • Collagen IV and I based coating results in disorganized hGEnC monolayer. • Physiologically relevant ECM may lead to down-regulation of self-produced matrices.

  18. The formation of quiescent glomerular endothelial cell monolayer in vitro is strongly dependent on the choice of extracellular matrix coating

    International Nuclear Information System (INIS)

    Pajęcka, Kamilla; Nielsen, Malik Nygaard; Hansen, Troels Krarup; Williams, Julie M.

    2017-01-01

    Background and aims: Nephropathy involves pathophysiological changes to the glomerulus. The primary glomerular endothelial cells (GEnCs) have emerged as an important tool for studying glomerulosclerotic mechanisms and in the screening process for drug-candidates. The success of the studies is dependent on the quality of the cell model. Therefore, we set out to establish an easy, reproducible model of the quiescent endothelial monolayer with the use of commercially available extracellular matrices (ECMs). Methods: Primary hGEnCs were seeded on various ECMs. Cell adhesion was monitored by an impedance sensing system. The localization of junctional proteins was assessed by immunofluorescence and the barrier function by passage of fluorescent dextrans and magnitude of VEGF response. Results: All ECM matrices except recombinant human laminin 111 (rhLN111) supported comparable cell proliferation. Culturing hGEnCs on rhLN521, rhLN511 or fibronectin resulted in a physiologically relevant barrier to 70 kDa dextrans which was 82% tighter than that formed on collagen type IV. Furthermore, only hGEnCs cultured on rhLN521 or rhLN511 showed plasma-membrane localized zonula occludens-1 and vascular endothelial cadherin indicative of proper tight and adherens junctions (AJ). Conclusion: We recommend culturing hGEnCs on the mature glomerular basement membrane laminin - rhLN521 – which, as the only commercially available ECM, promotes all of the characteristics of the quiescent hGEnC monolayer: cobblestone morphology, well-defined AJs and physiological perm-selectivity. - Highlights: • rhLN521, rhLN511 and hFN assure physiologically relevant permeability. • rhLN521 and rhLN511 ensure best cell morphology and adherens junction formation. • Collagen IV and I based coating results in disorganized hGEnC monolayer. • Physiologically relevant ECM may lead to down-regulation of self-produced matrices.

  19. Tiny cause with huge impact: polar instability through strong magneto-electric-elastic coupling in bulk EuTiO3.

    Science.gov (United States)

    Reuvekamp, Patrick; Caslin, Kevin; Guguchia, Zurab; Keller, Hugo; Kremer, Reinhard K; Simon, Arndt; Köhler, Jürgen; Bussmann-Holder, Annette

    2015-07-08

    EuTiO3 exhibits strong magneto-electric coupling at the onset of antiferromagnetic order below TN = 5.7 K. The dielectric permittivity drops at TN by 7% and recovers to normal values with increasing magnetic field. This effect is shown to stem from tiny lattice effects as seen in magnetostriction data which directly affect the soft optic mode and its polarizability coordinate. By combining experimental results with theory we show that marginal changes in the lattice parameter of the order of 0.01% have a more than 1000% effect on the transverse optic soft mode of ETO and thus easily induce a ferroelectric instability.

  20. Beta4 integrin-dependent formation of polarized three-dimensionalarchitecture confers resistance to apoptosis in normal and malignantmammary epithelium

    Energy Technology Data Exchange (ETDEWEB)

    Weaver, Valerie M.; Lelievre, Sophie; Lakins, Johnathon N.; Chrenek, Micah A.; Jones, Jonathan C.R.; Giancotti, Filippo; Werb, Zena; Bissell, Mina J.

    2002-08-27

    Tumor cells can evade chemotherapy by acquiring resistanceto apoptosis. We investigated the molecular mechanism whereby malignantand nonmalignant mammary epithelial cells become insensitive toapoptosis. We show that regardless of growth status formation ofpolarized, three-dimensional structures driven by basement membraneconfers protection to apoptosis in both nonmalignant and malignantmammary epithelial cells. By contrast, irrespective of their malignantstatus, nonpolarized structures are sensitive to induction of apoptosis.Resistance to apoptosis requires ligation of beta4 integrins, whichregulates tissue polarity, hemidesmosome formation and NFkB activation.Expression of beta4 integrin that lacks the hemidesmosome targetingdomain interferes with tissue polarity and NFkB activation and permitsapoptosis. These results indicate that integrin-induced polarity maydrive tumor cell resistance to apoptosis-inducing agents via effects onNFkB.

  1. Signals involved in the early TH1/TH2 polarization of an immune response depending on the type of antigen.

    Science.gov (United States)

    Bellinghausen, I; Brand, U; Enk, A H; Knop, J; Saloga, J

    1999-02-01

    The early production of distinct cytokines by epidermal cells (ECs) in response to antigen exposure may govern the development of TH1 -like immune responses, such as contact sensitivity, or TH2 -like immune responses, such as IgE-dependent allergies of the immediate type, depending on the type of antigen. The aim of this study was to compare the signals induced by protein allergens with those induced by haptens in ECs and subsequently in local draining lymph node cells (LNCs) or splenocytes. BALB/c mice were primed in vivo with the protein allergens ovalbumin or birch pollen or the haptens 2, 4-dinitrofluorobenzene or trinitrochlorbenzene, respectively, and cytokine and immunoglobulin secretions of responding splenocytes were measured by ELISA after in vitro coculture with ECs. Induction of cytokine mRNA expression in ECs and LNCs was analyzed by reverse transcriptase-PCR. In the presence of protein allergens, ECs enhance the induction of a TH2 immune response (IL-4 and IgE production of splenocytes), whereas a TH1 immune response (IFN-gamma and IgG2a production) was only induced in the context of haptens. Heat inactivation of ovalbumin did not diminish the development of a TH2 immune response. One direct effect of antigen on ECs was the earlier expression of IL-10 mRNA after stimulation with protein allergens (30 minutes) than with haptens (2 hours) in vitro. By using an in vivo approach, sensitization of the skin with trinitrochlorbenzene, but not with ovalbumin, resulted in an early induction of IL-1beta, IL-12p40, and IFN-gamma mRNA in LNCs, whereas IL-18 was induced by both. These data indicate that the type of antigen strongly influences the type of immune response by eliciting distinct signals already in the epithelium.

  2. Laser polarization dependent and magnetically control of group velocity in a dielectric medium doped with nanodiamond nitrogen vacancy centers

    Energy Technology Data Exchange (ETDEWEB)

    Asadpour, Seyyed Hossein; Rahimpour Soleimani, H., E-mail: Rahimpour@guilan.ac.ir

    2014-03-01

    In this paper, group velocity control of Gaussian beam in a dielectric medium doped with nanodiamond nitrogen vacancy (NV) centers under optical excitation is discussed. The shape of transmitted and reflected pulses from dielectric can be tuned by changing the intensity of magnetic field and polarization of the control beam. The effect of intensity of control beam on group velocity is also investigated.

  3. Visualization of Excitonic Structure in the Fenna-Matthews-OlsonPhotosynthetic Complex by Polarization-Dependent Two-DimensionalElectronic Spectroscopy

    Energy Technology Data Exchange (ETDEWEB)

    Department of Chemistry, The University of Chicago; Department of Biology, Department of Chemistry, Washington University; Fleming, Graham; Read, Elizabeth L.; Schlau-Cohen, Gabriela S.; Engel, Gregory S.; Wen, Jianzhong; Blankenship, Robert E.; Fleming, Graham R.

    2008-05-26

    Photosynthetic light-harvesting proceeds by the collection and highly efficient transfer of energy through a network of pigment-protein complexes. Inter-chromophore electronic couplings and interactions between pigments and the surrounding protein determine energy levels of excitonic states and dictate the mechanism of energy flow. The excitonic structure (orientation of excitonic transition dipoles) of pigment-protein complexes is generally deduced indirectly from x-ray crystallography in combination with predictions of transition energies and couplings in the chromophore site basis. Here, we demonstrate that coarse-grained excitonic structural information in the form of projection angles between transition dipole moments can be obtained from polarization-dependent two-dimensional electronic spectroscopy of an isotropic sample, particularly when the nonrephasing or free polarization decay signal rather than the photon echo signal is considered. The method provides an experimental link between atomic and electronic structure and accesses dynamical information with femtosecond time resolution. In an investigation of the Fenna-Matthews-Olson complex from green sulfur bacteria, energy transfer connecting two particular exciton states in the protein is isolated as being the primary contributor to a cross peak in the nonrephasing 2D spectrum at 400 fs under a specific sequence of polarized excitation pulses. The results suggest the possibility of designing experiments using combinations of tailored polarization sequencesto separate and monitor individual relaxation pathways.

  4. Quantum fluid dynamics based current-density functional study of a helium atom in a strong time-dependent magnetic field

    Science.gov (United States)

    Vikas, Hash(0x125f4490)

    2011-02-01

    Evolution of the helium atom in a strong time-dependent (TD) magnetic field ( B) of strength up to 1011 G is investigated through a quantum fluid dynamics (QFD) based current-density functional theory (CDFT). The TD-QFD-CDFT computations are performed through numerical solution of a single generalized nonlinear Schrödinger equation employing vector exchange-correlation potentials and scalar exchange-correlation density functionals that depend both on the electronic charge-density and the current-density. The results are compared with that obtained from a B-TD-QFD-DFT approach (based on conventional TD-DFT) under similar numerical constraints but employing only scalar exchange-correlation potential dependent on electronic charge-density only. The B-TD-QFD-DFT approach, at a particular TD magnetic field-strength, yields electronic charge- and current-densities as well as exchange-correlation potential resembling with that obtained from the time-independent studies involving static (time-independent) magnetic fields. However, TD-QFD-CDFT electronic charge- and current-densities along with the exchange-correlation potential and energy differ significantly from that obtained using B-TD-QFD-DFT approach, particularly at field-strengths >109 G, representing dynamical effects of a TD field. The work concludes that when a helium atom is subjected to a strong TD magnetic field of order >109 G, the conventional TD-DFT based approach differs "dynamically" from the CDFT based approach under similar computational constraints.

  5. Quantum fluid dynamics based current-density functional study of a helium atom in a strong time-dependent magnetic field

    International Nuclear Information System (INIS)

    Vikas

    2011-01-01

    Evolution of the helium atom in a strong time-dependent (TD) magnetic field (B) of strength up to 10 11 G is investigated through a quantum fluid dynamics (QFD) based current-density functional theory (CDFT). The TD-QFD-CDFT computations are performed through numerical solution of a single generalized nonlinear Schroedinger equation employing vector exchange-correlation potentials and scalar exchange-correlation density functionals that depend both on the electronic charge-density and the current-density. The results are compared with that obtained from a B-TD-QFD-DFT approach (based on conventional TD-DFT) under similar numerical constraints but employing only scalar exchange-correlation potential dependent on electronic charge-density only. The B-TD-QFD-DFT approach, at a particular TD magnetic field-strength, yields electronic charge- and current-densities as well as exchange-correlation potential resembling with that obtained from the time-independent studies involving static (time-independent) magnetic fields. However, TD-QFD-CDFT electronic charge- and current-densities along with the exchange-correlation potential and energy differ significantly from that obtained using B-TD-QFD-DFT approach, particularly at field-strengths >10 9 G, representing dynamical effects of a TD field. The work concludes that when a helium atom is subjected to a strong TD magnetic field of order >10 9 G, the conventional TD-DFT based approach differs 'dynamically' from the CDFT based approach under similar computational constraints. (author)

  6. Material and device studies for the development of ultra-violet light emitting diodes (UV-LEDS) along polar, non-polar and semi-polar directions

    Science.gov (United States)

    Chandrasekaran, Ramya

    Over the past few years, significant effort was dedicated to the development of ultraviolet light emitting diodes (UV-LEDs) for a variety of applications. Such applications include chemical and biological detection, water purification and solid-state lighting. III-Nitride LEDs based on multiple quantum wells (MQWs) grown along the conventional [0001] (polar) direction suffer from the quantum confined Stark effect (QCSE), due to the existence of strong electric fields that arise from spontaneous and piezoelectric polarization. Thus, there is strong motivation to develop MQW-based III-nitride LED structures grown along non-polar and semi-polar directions. The goal of this dissertation is to develop UV-LEDs along the [0001] polar and [11 2¯ 0] non-polar directions by the method of Molecular Beam Epitaxy (MBE). The polar and non-polar LEDs were grown on the C-plane and R-plane sapphire substrates respectively. This work is a combination of materials science studies related to the nucleation, growth and n- and p-type doping of III-nitride films on these two substrates, as well as device studies related to fabrication and characterization of UV-LEDs. It was observed that the crystallographic orientation of the III-nitride films grown on R-plane sapphire depends strongly on the kinetic conditions of growth of the Aluminum Nitride (AIN) buffer. Specifically, growth of the AIN buffer under group III-rich conditions leads to nitride films having the (11 2¯ 0) non polar planes parallel to the sapphire surface, while growth of the buffer under nitrogen rich conditions leads to nitride films with the (11 2¯ 6) semi-polar planes parallel to the sapphire surface. The electron concentration and mobility for the films grown along the polar, non-polar and semi-polar directions were investigated. P-type doping of Gallium Nitride (GaN) films grown on the nonpolar (11 2¯ 0) plane do not suffer from polarity inversion and thus the material was doped p-type with a hole concentration

  7. First measurement of the polarization observable E and helicity-dependent cross sections in single π0 photoproduction from quasi-free nucleons

    Directory of Open Access Journals (Sweden)

    M. Dieterle

    2017-07-01

    Full Text Available The double-polarization observable E and the helicity-dependent cross sections σ1/2 and σ3/2 have been measured for the first time for single π0 photoproduction from protons and neutrons bound in the deuteron at the electron accelerator facility MAMI in Mainz, Germany. The experiment used a circularly polarized photon beam and a longitudinally polarized deuterated butanol target. The reaction products, recoil nucleons and decay photons from the π0 meson were detected with the Crystal Ball and TAPS electromagnetic calorimeters. Effects from nuclear Fermi motion were removed by a kinematic reconstruction of the π0N final state. A comparison to data measured with a free proton target showed that the absolute scale of the cross sections is significantly modified by nuclear final-state interaction (FSI effects. However, there is no significant effect on the asymmetry E since the σ1/2 and σ3/2 components appear to be influenced in a similar way. Thus, the best approximation of the two helicity-dependent cross sections for the free neutron is obtained by combining the asymmetry E measured with quasi-free neutrons and the unpolarized cross section corrected for FSI effects under the assumption that the FSI effects are similar for neutrons and protons.

  8. Polarization-dependent transverse-stress sensing characters of the gold-coated and liquid crystal filled photonic crystal fiber based on Surface Plasmon Resonance

    Science.gov (United States)

    Liu, Hai; Zhu, Chenghao; Wang, Yan; Tan, Ce; Li, Hongwei

    2018-03-01

    A transverse-stress sensor with enhanced sensitivity based on nematic liquid crystal (NLC) filled photonic crystal fiber (PCF) is proposed and analyzed by using the finite element method (FEM). The central hole of the PCF is infiltrated with NLC material with an adjustable rotation angle to achieve the polarization-dependent wavelength-selective sensing. And the combined use of side-hole structure and Surface Plasmon Resonance (SPR) technology enhanced the transverse-stress sensitivity enormously. Results reveal that the sensor can achieve a high sensitivity based on the polarization filter characteristic at special wavelengths. Besides that, the temperature and the transverse-stress in either direction can be effectively discriminated through dual-parameter demodulation method by adjusting the rotation angle of the NLC to introduce a new degree of freedom for sensing.

  9. Polarization dependence of the magnetic fluctuations in the weak itinerant ferromagnet MnSi below T{sub c}

    Energy Technology Data Exchange (ETDEWEB)

    Boeni, P.; Tixier, S. [Paul Scherrer Inst. (PSI), Villigen (Switzerland); Endoh, Y. [Tohoku Univ., Sendai (Japan); Roessli, B. [Institut Max von Laue - Paul Langevin, 75 - Paris (France); Shirane, G. [Brookhaven (United States)

    1997-09-01

    The dispersion of the spin-flip and non-spin-flip excitations in the weak itinerant ferromagnet MnSi have been measured in the ferromagnetic phase using inelastic polarized neutron scattering. Spin wave excitations are well defined at energy transfers as large as 7 meV. The cross section of the non-spin-flip excitations is compatible with a quasielastic response function. (author) 2 figs., 3 refs.

  10. Dependence of InGaN solar cell performance on polarization-induced electric field and carrier lifetime

    International Nuclear Information System (INIS)

    Yang Jing; Zhao De-Gang; Jiang De-Sheng; Liu Zong-Shun; Chen Ping; Li Liang; Wu Liang-Liang; Le Ling-Cong; Li Xiao-Jing; He Xiao-Guang; Yang Hui; Wang Hui; Zhu Jian-Jun; Zhang Shu-Ming; Zhang Bao-Shun

    2013-01-01

    The effects of Mg-induced net acceptor doping concentration and carrier lifetime on the performance of a p—i—n InGaN solar cell are investigated. It is found that the electric field induced by spontaneous and piezoelectric polarization in the i-region could be totally shielded when the Mg-induced net acceptor doping concentration is sufficiently high. The polarization-induced potential barriers are reduced and the short circuit current density is remarkably increased from 0.21 mA/cm 2 to 0.95 mA/cm 2 by elevating the Mg doping concentration. The carrier lifetime determined by defect density of i-InGaN also plays an important role in determining the photovoltaic properties of solar cell. The short circuit current density severely degrades, and the performance of InGaN solar cell becomes more sensitive to the polarization when carrier lifetime is lower than the transit time. This study demonstrates that the crystal quality of InGaN absorption layer is one of the most important challenges in realizing high efficiency InGaN solar cells. (interdisciplinary physics and related areas of science and technology)

  11. Spin-dependent energy distribution of B-hadrons from polarized top decays considering the azimuthal correlation rate

    Directory of Open Access Journals (Sweden)

    S.M. Moosavi Nejad

    2016-04-01

    Full Text Available Basically, the energy distribution of bottom-flavored hadrons produced through polarized top quark decays t(↑→W++b(→Xb, is governed by the unpolarized rate and the polar and the azimuthal correlation functions which are related to the density matrix elements of the decay t(↑→bW+. Here we present, for the first time, the analytical expressions for the O(αs radiative corrections to the differential azimuthal decay rates of the partonic process t(↑→b+W+ in two helicity systems, which are needed to study the azimuthal distribution of the energy spectrum of the hadrons produced in polarized top decays. These spin-momentum correlations between the top quark spin and its decay product momenta will allow the detailed studies of the top decay mechanism. Our predictions of the hadron energy distributions also enable us to deepen our knowledge of the hadronization process and to test the universality and scaling violations of the bottom-flavored meson fragmentation functions.

  12. Quantitative analysis with advanced compensated polarized light microscopy on wavelength dependence of linear birefringence of single crystals causing arthritis

    Science.gov (United States)

    Takanabe, Akifumi; Tanaka, Masahito; Taniguchi, Atsuo; Yamanaka, Hisashi; Asahi, Toru

    2014-07-01

    To improve our ability to identify single crystals causing arthritis, we have developed a practical measurement system of polarized light microscopy called advanced compensated polarized light microscopy (A-CPLM). The A-CPLM system is constructed by employing a conventional phase retardation plate, an optical fibre and a charge-coupled device spectrometer in a polarized light microscope. We applied the A-CPLM system to measure linear birefringence (LB) in the visible region, which is an optical anisotropic property, for tiny single crystals causing arthritis, i.e. monosodium urate monohydrate (MSUM) and calcium pyrophosphate dihydrate (CPPD). The A-CPLM system performance was evaluated by comparing the obtained experimental data using the A-CPLM system with (i) literature data for a standard sample, MgF2, and (ii) experimental data obtained using an established optical method, high-accuracy universal polarimeter, for the MSUM. The A-CPLM system was found to be applicable for measuring the LB spectra of the single crystals of MSUM and CPPD, which cause arthritis, in the visible regions. We quantitatively reveal the large difference in LB between MSUM and CPPD crystals. These results demonstrate the usefulness of the A-CPLM system for distinguishing the crystals causing arthritis.

  13. Spin-dependent scattering and the spin polarization of a diffusive current in partly disordered L10 epitaxial FePd

    International Nuclear Information System (INIS)

    Seemann, K M; Hickey, M C; Baltz, V; Hickey, B J; Marrows, C H

    2010-01-01

    We report magnetic domain wall (DW) resistance in epitaxial films of FePd. When equal numbers of Fe and Pd atoms are present, this material forms an ordered structure with alternating crystal planes of Fe and Pd. We prepared films enriched with Pd to varying degrees, gradually degrading this structure. As might be expected, this increased the electrical resistivity of the films by introducing extra defects that can scatter electrons. However, unexpectedly, the additional resistance arising from the ∼10 nm thick DWs rose as a proportion of the overall resistivity, roughly doubling when halving the degree of chemical ordering-as determined from x-ray diffraction measurements-within the films. These data can be used to infer a rise in the spin polarization of the current flowing in the layers when extra Pd atoms are introduced. On the other hand, a separate measurement of spin polarization using a superconducting point contact technique that is insensitive to electron scattering revealed no changes as extra Pd was introduced. We conclude that Pd atoms scatter electrons of one spin far more strongly than the other, suggesting a possible means of producing highly spin-polarized currents for use in spintronic devices.

  14. Preliminary Analysis of Chinese GF-3 SAR Quad-Polarization Measurements to Extract Winds in Each Polarization

    Directory of Open Access Journals (Sweden)

    Lin Ren

    2017-11-01

    Full Text Available This study analyzed the noise equivalent sigma zero (NESZ and ocean wind sensitivity for Chinese C-band Gaofen-3 (GF-3 quad-polarization synthetic aperture radar (SAR measurements to facilitate further operational wind extraction from GF-3 data. Data from the GF-3 quad-polarization SAR and collocated winds from both NOAA/NCEP Global Forecast System (GFS atmospheric model and National Data Buoy Center (NDBC buoys were used in the analysis. For NESZ, the co-polarization was slightly higher compared to the cross-polarization. Regarding co-polarization and cross-polarization, NESZ was close to RadarSAT-2 and Sentinel-1 A. Wind sensitivity was analyzed by evaluating the dependence on winds in terms of normalized radar cross-sections (NRCS and polarization combinations. The closest geophysical model function (GMF and the polarization ratio (PR model to GF-3 data were determined by comparing data and the model results. The dependence of co-polarized NRCS on wind speed and azimuth angle was consistent with the proposed GMF models. The combination of CMOD5 and CMOD5.N was considered to be the closest GMF in co-polarization. The cross-polarized NRCS exhibited a strong linear relationship with moderate wind speeds higher than 4 m·s−1, but a weak correlation with the azimuth angle. The proposed model was considered as the closest GMF in cross-polarization. For polarization combinations, PR and polarization difference (PD were considered. PR increased only with the incidence angle, whereas PD increased with wind speed and varied with azimuth angle. There were three very close PR models and each can be considered as the closest. Preliminary results indicate that GF-3 quad-polarization data are valid and have the ability to extract winds in each polarization.

  15. Quantum fluid dynamics based current-density functional study of a helium atom in a strong time-dependent magnetic field

    Energy Technology Data Exchange (ETDEWEB)

    Vikas [Quantum Chemistry Group, Department of Chemistry and Centre of Advanced Studies in Chemistry, Panjab University, 160014 Chandigrah (India)

    2011-02-15

    Evolution of the helium atom in a strong time-dependent (TD) magnetic field (B) of strength up to 10{sup 11} G is investigated through a quantum fluid dynamics (QFD) based current-density functional theory (CDFT). The TD-QFD-CDFT computations are performed through numerical solution of a single generalized nonlinear Schroedinger equation employing vector exchange-correlation potentials and scalar exchange-correlation density functionals that depend both on the electronic charge-density and the current-density. The results are compared with that obtained from a B-TD-QFD-DFT approach (based on conventional TD-DFT) under similar numerical constraints but employing only scalar exchange-correlation potential dependent on electronic charge-density only. The B-TD-QFD-DFT approach, at a particular TD magnetic field-strength, yields electronic charge- and current-densities as well as exchange-correlation potential resembling with that obtained from the time-independent studies involving static (time-independent) magnetic fields. However, TD-QFD-CDFT electronic charge- and current-densities along with the exchange-correlation potential and energy differ significantly from that obtained using B-TD-QFD-DFT approach, particularly at field-strengths >10{sup 9} G, representing dynamical effects of a TD field. The work concludes that when a helium atom is subjected to a strong TD magnetic field of order >10{sup 9} G, the conventional TD-DFT based approach differs 'dynamically' from the CDFT based approach under similar computational constraints. (author)

  16. Thickness Dependence of Magnetic Relaxation and E-J Characteristics in Superconducting (Gd-Y)-Ba-Cu-O Films with Strong Vortex Pinning

    Energy Technology Data Exchange (ETDEWEB)

    Polat, Ozgur [ORNL; Sinclair IV, John W [ORNL; Zuev, Yuri L [ORNL; Thompson, James R [ORNL; Christen, David K [ORNL; Cook, Sylvester W [ORNL; Kumar, Dhananjay [ORNL; Chen, Y [SuperPower Incorporated, Schenectady, New York; Selvamanickam, V. [SuperPower Incorporated, Schenectady, New York

    2011-01-01

    The dependence of the critical current density Jc on temperature, magnetic field, and film thickness has been investigated in (Gd-Y)BaCu-oxide materials of 0.7, 1.4, and 2.8 m thickness. Generally, the Jc decreases with film thickness at investigated temperatures and magnetic fields. The nature and strength of the pinning centers for vortices have been identified through angular and temperature measurements, respectively. These films do not exhibit c-axis correlated vortex pinning, but do have correlated defects oriented near the ab-planes. For all film thicknesses studied, strong pinning dominates at most temperatures. The vortex dynamics were investigated through magnetic relaxation studies in the temperature range of 5 77 K in 1 T and 3 T applied magnetic fields, H || surface-normal. The creep rate S is thickness dependent at high temperatures, implying that the pinning energy is also thickness dependent. Maley analyses of the relaxation data show an inverse power law variation for the effective pinning energy Ueff ~ (J0/J) . Finally, the electric field-current density (E-J) characteristics were determined over a wide range of dissipation by combining experimental results from transport, swept field magnetometry (VSM), and Superconducting Quantum Interference Device (SQUID) magnetometry. We develop a self-consistent model of the combined experimental results, leading to an estimation of the critical current density Jc0(T) in the absence of flux creep.

  17. Spin-polarized relativistic linear-muffin-tin-orbital method: Volume-dependent electronic structure and magnetic moment of plutonium

    International Nuclear Information System (INIS)

    Solovyev, I.V.; Liechtenstein, A.I.; Gubanov, V.A.; Antropov, V.P.; Andersen, O.K.

    1991-01-01

    The linear-muffin-tin-orbital method is generalized to the case of relativistic and spin-polarized self-consistent band calculations. Our formalism is analogous to the standard orthogonal--linear-muffin-tin-orbital formalism, except that the potential functions and the potential parameters are now matrices. The method is used to perform density-functional calculations for fcc plutonium with different atomic volumes. The formation of spin and orbital magnetic moments, as well as the changes in the energy bands for volume changes corresponding to the α-δ transition, are investigated. The calculated magnetic moments agree quite well with the experimental ones

  18. Suomi National Polar-Orbiting Partnership Visible Infrared Imaging Radiometer Suite Polarization Sensitivity Analysis

    Science.gov (United States)

    Sun, Junqiang; Xiong, Xiaoxiong; Waluschka, Eugene; Wang, Menghua

    2016-01-01

    The Visible Infrared Imaging Radiometer Suite (VIIRS) is one of five instruments onboard the Suomi National Polar-Orbiting Partnership (SNPP) satellite that launched from Vandenberg Air Force Base, California, on October 28, 2011. It is a whiskbroom radiometer that provides +/-56.28deg scans of the Earth view. It has 22 bands, among which 14 are reflective solar bands (RSBs). The RSBs cover a wavelength range from 410 to 2250 nm. The RSBs of a remote sensor are usually sensitive to the polarization of incident light. For VIIRS, it is specified that the polarization factor should be smaller than 3% for 410 and 862 nm bands and 2.5% for other RSBs for the scan angle within +/-45deg. Several polarization sensitivity tests were performed prelaunch for SNPP VIIRS. The first few tests either had large uncertainty or were less reliable, while the last one was believed to provide the more accurate information about the polarization property of the instrument. In this paper, the measured data in the last polarization sensitivity test are analyzed, and the polarization factors and phase angles are derived from the measurements for all the RSBs. The derived polarization factors and phase angles are band, detector, and scan angle dependent. For near-infrared bands, they also depend on the half-angle mirror side. Nevertheless, the derived polarization factors are all within the specification, although the strong detector dependence of the polarization parameters was not expected. Compared to the Moderate Resolution Imaging Spectroradiometer on both Aqua and Terra satellites, the polarization effect on VIIRS RSB is much smaller.

  19. Drosophila tensin plays an essential role in cell migration and planar polarity formation during oogenesis by mediating integrin-dependent extracellular signals to actin organization.

    Science.gov (United States)

    Cha, In Jun; Lee, Jang Ho; Cho, Kyoung Sang; Lee, Sung Bae

    2017-03-11

    Oogenesis in Drosophila involves very dynamic cellular changes such as cell migration and polarity formation inside an ovary during short period. Previous studies identified a number of membrane-bound receptors directly receiving certain types of extracellular inputs as well as intracellular signalings to be involved in the regulation of these dynamic cellular changes. However, yet our understanding on exactly how these receptor-mediated extracellular inputs lead to dynamic cellular changes remains largely unclear. Here, we identified Drosophila tensin encoded by blistery (by) as a novel regulator of cell migration and planar polarity formation and characterized the genetic interaction between tensin and integrin during oogenesis. Eggs from by mutant showed decreased hatching rate and morphological abnormality, a round-shape, compared to the wild-type eggs. Further analyses revealed that obvious cellular defects such as defective border cell migration and planar polarity formation might be primarily associated with the decreased hatching rate and the round-shape phenotype of by mutant eggs, respectively. Moreover, by mutation also induced marked defects in F-actin organization closely associated with both cell migration and planar polarity formation during oogenesis of Drosophila. Notably, all these defective phenotypes observed in by mutant eggs became much severer by reduced level of integrin, indicative of a close functional association between integrin and tensin during oogenesis. Collectively, our findings suggest that tensin acts as a crucial regulator of dynamic cellular changes during oogenesis by bridging integrin-dependent extracellular signals to intracellular cytoskeletal organization. Copyright © 2017 Elsevier Inc. All rights reserved.

  20. Strongly Nonlinear Dependence of Energy Transfer Rate on sp(2) Carbon Content in Reduced Graphene Oxide-Quantum Dot Hybrid Structures.

    Science.gov (United States)

    Dong, Yitong; Son, Dong Hee

    2015-01-02

    The dependence of the energy transfer rate on the content of sp(2)-hybridized carbon atoms in the hybrid structures of reduced graphene oxide (RGO) and Mn-doped quantum dot (QD(Mn)) was investigated. Taking advantage of the sensitivity of QD(Mn)'s dopant luminescence lifetime only to the energy transfer process without interference from the charge transfer process, the correlation between the sp(2) carbon content in RGO and the rate of energy transfer from QD(Mn) to RGO was obtained. The rate of energy transfer showed a strongly superlinear increase with increasing sp(2) carbon content in RGO, suggesting the possible cooperative behavior of sp(2) carbon domains in the energy transfer process as the sp(2) carbon content increases.

  1. Verification test problems for the calculation of probability of loss of assured safety in temperature-dependent systems with multiple weak and strong links.

    Energy Technology Data Exchange (ETDEWEB)

    Johnson, Jay Dean (ProStat, Mesa, AZ); Oberkampf, William Louis; Helton, Jon Craig (Arizona State University, Tempe, AZ)

    2006-06-01

    Four verification test problems are presented for checking the conceptual development and computational implementation of calculations to determine the probability of loss of assured safety (PLOAS) in temperature-dependent systems with multiple weak links (WLs) and strong links (SLs). The problems are designed to test results obtained with the following definitions of loss of assured safety: (1) Failure of all SLs before failure of any WL, (2) Failure of any SL before failure of any WL, (3) Failure of all SLs before failure of all WLs, and (4) Failure of any SL before failure of all WLs. The test problems are based on assuming the same failure properties for all links, which results in problems that have the desirable properties of fully exercising the numerical integration procedures required in the evaluation of PLOAS and also possessing simple algebraic representations for PLOAS that can be used for verification of the analysis.

  2. Polarization Optics

    OpenAIRE

    Fressengeas, Nicolas

    2010-01-01

    The physics of polarization optics *Polarized light propagation *Partially polarized light; DEA; After a brief introduction to polarization optics, this lecture reviews the basic formalisms for dealing with it: Jones Calculus for totally polarized light and Stokes parameters associated to Mueller Calculus for partially polarized light.

  3. Assessment Of Mold-Design Dependent Textures In CIM-Components By Polarized Light Optical Texture Analysis (PLOTA)

    International Nuclear Information System (INIS)

    Kern, Frank; Rauch, Johannes; Gadow, Rainer

    2007-01-01

    By thermoplastic ceramic injection moulding (CIM) ceramic components of high complexity can be produced in a large number of items at low dimensional tolerances. The cost advantage by the high degree of automation leads to an economical mass-production. The structure of injection-moulded components is determined by the form filling behaviour and viscosity of the feedstock, the machine parameters, the design of the mold and the gate design. With an adapted mold- and gate-design CIM-components without textures are possible. The ''Polarized Light Optical Texture analysis'' (PLOTA) makes it possible to inspect the components and detect and quantify the textures produced by a new mold. Based on the work of R. Fischer (2004) the PLOTA procedure was improved by including the possibility to measure the inclination angle and thus describe the orientation of the grains in three dimensions. Sampled thin sections of ceramic components are analysed under the polarization microscope and are brought in diagonal position. Pictures are taken with a digital camera. The pictures are converted in the L*a*b*- colour space and the crystals color values a* and b* in the picture are measured. The color values are compared with the values of a quartz wedge, which serves as universal standard. From the received values the inclination angle can be calculated relative to the microscope axis. It is possible to use the received data quantitatively e.g. for the FEM supported simulation of texture-conditioned divergences of mechanical values. Thus the injection molding parameters can be optimized to obtain improved mechanical properties

  4. The interplanetary magnetic field By-dependent field-aligned current in the dayside polar cap under quiet conditions

    International Nuclear Information System (INIS)

    Yamauchi, M.; Araki, T.

    1989-01-01

    Spatial distribution and temporal variation of the interplanetary magnetic field (IMF) B y -dependent cusp region field-aligned currents (FACs) during quiet periods were studied by use of magnetic data observed by Magsat. The analysis was made for 11 events (each event lasts more than one and a half days) when the IMF B y component was steadily large and B x was relatively small (|B z | y |). Results of the analysis of total 62 half-day periods for the IMF B y -dependent cusp region FAC are summarized as follows: (1) the IMF B y -dependent cusp region FAC is located at around 86 degree-87 degree invariant latitude local noon, which is more poleward than the location of the IMF B z -dependent cusp region FAC; (2) the current density of this FAC is greater than previous studies (≥ 4 μA/m 2 for IMF B y = 6 nT); (3) there are two time scales for the IMF B y -dependent cusp region FAC to appear: the initial rise of the current is on a short time scale, ∼ 10 min, and it is followed by a gradual increase on a time scale of several hours to a half day; (4) the seasonal change of this FAC is greater than that of the nightside region 1 or region 2 FACs; (5) the IMF B z -dependent cusp region FAC is not well observed around the cusp when the IMF B y -dependent cusp region FAC is intense

  5. Low-cost fabrication and polar-dependent switching uniformity of memory devices using alumina interfacial layer and Ag nanoparticle monolayer

    Directory of Open Access Journals (Sweden)

    Peng Xia

    2017-11-01

    Full Text Available A facile and low-cost process was developed for fabricating write-once-read-many-times (WORM Cu/Ag NPs/Alumina/Al memory devices, where the alumina passivation layer formed naturally in air at room temperature, whereas the Ag nanoparticle monolayer was in situ prepared through thermal annealing of a 4.5 nm Ag film in air at 150°C. The devices exhibit irreversible transition from initial high resistance (OFF state to low resistance (ON state, with ON/OFF ratio of 107, indicating the introduction of Ag nanoparticle monolayer greatly improves ON/OFF ratio by four orders of magnitude. The uniformity of threshold voltages exhibits a polar-dependent behavior, and a narrow range of threshold voltages of 0.40 V among individual devices was achieved upon the forward voltage. The memory device can be regarded as two switching units connected in series. The uniform alumina interfacial layer and the non-uniform distribution of local electric fields originated from Ag nanoparticles might be responsible for excellent switching uniformity. Since silver ions in active layer can act as fast ion conductor, a plausible mechanism relating to the formation of filaments sequentially among the two switching units connected in series is suggested for the polar-dependent switching behavior. Furthermore, we demonstrate both alumina layer and Ag NPs monolayer play essential roles in improving switching parameters based on comparative experiments.

  6. Low-cost fabrication and polar-dependent switching uniformity of memory devices using alumina interfacial layer and Ag nanoparticle monolayer

    Science.gov (United States)

    Xia, Peng; Li, Luman; Wang, Pengfei; Gan, Ying; Xu, Wei

    2017-11-01

    A facile and low-cost process was developed for fabricating write-once-read-many-times (WORM) Cu/Ag NPs/Alumina/Al memory devices, where the alumina passivation layer formed naturally in air at room temperature, whereas the Ag nanoparticle monolayer was in situ prepared through thermal annealing of a 4.5 nm Ag film in air at 150°C. The devices exhibit irreversible transition from initial high resistance (OFF) state to low resistance (ON) state, with ON/OFF ratio of 107, indicating the introduction of Ag nanoparticle monolayer greatly improves ON/OFF ratio by four orders of magnitude. The uniformity of threshold voltages exhibits a polar-dependent behavior, and a narrow range of threshold voltages of 0.40 V among individual devices was achieved upon the forward voltage. The memory device can be regarded as two switching units connected in series. The uniform alumina interfacial layer and the non-uniform distribution of local electric fields originated from Ag nanoparticles might be responsible for excellent switching uniformity. Since silver ions in active layer can act as fast ion conductor, a plausible mechanism relating to the formation of filaments sequentially among the two switching units connected in series is suggested for the polar-dependent switching behavior. Furthermore, we demonstrate both alumina layer and Ag NPs monolayer play essential roles in improving switching parameters based on comparative experiments.

  7. Resonant inelastic X-ray spectroscopy of atoms and simple molecules: Satellite features and dependence on energy detuning and photon polarization

    Energy Technology Data Exchange (ETDEWEB)

    Žitnik, M., E-mail: matjaz.zitnik@ijs.si [Jožef Stefan Institute, P.O. Box 3000, SI-1001 Ljubljana (Slovenia); University of Ljubljana, Faculty of Mathematics and Physics, Jadranska 21, SI-1000 Ljubljana (Slovenia); Kavčič, M.; Bohinc, R.; Bučar, K.; Mihelič, A. [Jožef Stefan Institute, P.O. Box 3000, SI-1001 Ljubljana (Slovenia); Cao, W. [Research Centre for Molecular Materials, University of Oulu, P.O. Box 3000, FIN-90014 Oulu (Finland); Guillemin, R.; Journel, L.; Marchenko, T.; Carniato, S.; Kawerk, E. [Sorbonne Universités, UPMC Univ Paris 06, UMR 7614, Laboratoire de Chimie Physique Matière et Rayonnement, F-75005 Paris (France); CNRS, UMR 7614, Laboratoire de Chimie Physique Matière et Rayonnement, F-75005 Paris (France); Piancastelli, M.N. [Sorbonne Universités, UPMC Univ Paris 06, UMR 7614, Laboratoire de Chimie Physique Matière et Rayonnement, F-75005 Paris (France); CNRS, UMR 7614, Laboratoire de Chimie Physique Matière et Rayonnement, F-75005 Paris (France); Department of Physics and Astronomy, Uppsala University, P.O. Box 516, 75120 Uppsala (Sweden); Simon, M. [Sorbonne Universités, UPMC Univ Paris 06, UMR 7614, Laboratoire de Chimie Physique Matière et Rayonnement, F-75005 Paris (France); CNRS, UMR 7614, Laboratoire de Chimie Physique Matière et Rayonnement, F-75005 Paris (France)

    2015-10-15

    We summarize recent results dealing with high resolution (resonant) X-ray spectroscopy of atomic and molecular targets in the tender X-ray energy region. We comment on advantages, new possibilities and problems related to RIXS spectroscopy with respect to the standard photoabsorption technique, where scanning the probe energy is the only option. In particular, three research areas are covered: X-ray emission mediated by energy dependent photoabsorption to multi-electron excited states, the Cl K core-hole clock studies exemplified by systematic study of chloro(fluoro)-hydrocarbon targets and the polarization dependent X-ray emission studies. Due to its spectral selectivity and simultaneous detection capability, high resolution wavelength dispersive X-ray spectroscopy has the capability to resolve structural and dynamical properties of matter within new instrumentation frontiers.

  8. Effect of atomic vibrations in XANES: polarization-dependent damping of the fine structure at the Cu K-edge of (creat)2CuCl4.

    Science.gov (United States)

    Šipr, Ondřej; Vackář, Jiří; Kuzmin, Alexei

    2016-11-01

    Polarization-dependent damping of the fine structure in the Cu K-edge spectrum of creatinium tetrachlorocuprate [(creat) 2 CuCl 4 ] in the X-ray absorption near-edge structure (XANES) region is shown to be due to atomic vibrations. These vibrations can be separated into two groups, depending on whether the respective atoms belong to the same molecular block; individual molecular blocks can be treated as semi-rigid entities while the mutual positions of these blocks are subject to large mean relative displacements. The effect of vibrations can be efficiently included in XANES calculations by using the same formula as for static systems but with a modified free-electron propagator which accounts for fluctuations in interatomic distances.

  9. Polarization in Sagittarius A*

    OpenAIRE

    Bower, Geoffrey C.

    2000-01-01

    We summarize the current state of polarization observations of Sagittarius A*, the compact radio source and supermassive black hole candidate in the Galactic Center. These observations are providing new tools for understanding accretion disks, jets and their environments. Linear polarization observations have shown that Sgr A* is unpolarized at frequencies as high as 86 GHz. However, recent single-dish observations indicate that Sgr A* may have strong linear polarization at frequencies higher...

  10. Using a quantum well heterostructure to study the longitudinal and transverse electric field components of a strongly focused laser beam

    NARCIS (Netherlands)

    Kihara Rurimo, G.; Schardt, M.; Quabis, S.; Malzer, S.; Dotzler, C.; Winkler, A.; Leuchs, G.; Döhler, G.H.; Driscoll, D.; Hanson, M.; Gossard, A.C.; Pereira, S.F.

    2006-01-01

    We report a method to measure the electric energy density of longitudinal and transverse electric field components of strongly focused polarized laser beams. We used a quantum well photodetector and exploited the polarization dependent optical transitions of light holes and heavy holes to probe the

  11. Carbon dots with strong excitation-dependent fluorescence changes towards pH. Application as nanosensors for a broad range of pH

    Energy Technology Data Exchange (ETDEWEB)

    Barati, Ali [Faculty of Chemistry, Institute for Advanced Studies in Basic Sciences, Zanjan (Iran, Islamic Republic of); Department of Chemistry, Razi University, Kermanshah (Iran, Islamic Republic of); Shamsipur, Mojtaba, E-mail: mshamsipur@yahoo.com [Department of Chemistry, Razi University, Kermanshah (Iran, Islamic Republic of); Abdollahi, Hamid, E-mail: abd@iasbs.ac.ir [Faculty of Chemistry, Institute for Advanced Studies in Basic Sciences, Zanjan (Iran, Islamic Republic of)

    2016-08-10

    In this study, preparation of novel pH-sensitive N-doped carbon dots (NCDs) using glucose and urea is reported. The prepared NCDs present strong excitation-dependent fluorescence changes towards the pH that is a new behavior from these nanomaterials. By taking advantage of this unique behavior, two separated ratiometric pH sensors using emission spectra of the NCDs for both acidic (pH 2.0 to 8.0) and basic (pH 7.0 to 14.0) ranges of pH are constructed. Additionally, by considering the entire Excitation–Emission Matrix (EEM) of NCDs as analytical signal and using a suitable multivariate calibration method, a broad range of pH from 2.0 to 14.0 was well calibrated. The multivariate calibration method was independent from the concentration of NCDs and resulted in a very low average prediction error of 0.067 pH units. No changes in the predicted pH under UV irradiation (for 3 h) and at high ionic strength (up to 2 M NaCl) indicated the high stability of this pH nanosensor. The practicality of this pH nanosensor for pH determination in real water samples was validated with good accuracy and repeatability. - Highlights: • Novel pH-sensitive carbon dots with strong FL changes towards pH are reported. • Ratiometric FL pH-sensors for both acidic and basic ranges of pH are constructed. • Multivariate calibration methods were used to calibrate a broad range of pH. • Using EEM of carbon dots and ANN, pH from 2.0 to 14.0 was well calibrated. • The pH prediction is stable even at high ionic strength up to 2 M NaCl.

  12. Linear Polarization, Circular Polarization, and Depolarization of Gamma-ray Bursts: A Simple Case of Jitter Radiation

    Energy Technology Data Exchange (ETDEWEB)

    Mao, Jirong; Wang, Jiancheng, E-mail: jirongmao@mail.ynao.ac.cn [Yunnan Observatories, Chinese Academy of Sciences, 650011 Kunming, Yunnan Province (China)

    2017-04-01

    Linear and circular polarizations of gamma-ray bursts (GRBs) have been detected recently. We adopt a simplified model to investigate GRB polarization characteristics in this paper. A compressed two-dimensional turbulent slab containing stochastic magnetic fields is considered, and jitter radiation can produce the linear polarization under this special magnetic field topology. Turbulent Faraday rotation measure (RM) of this slab makes strong wavelength-dependent depolarization. The jitter photons can also scatter with those magnetic clumps inside the turbulent slab, and a nonzero variance of the Stokes parameter V can be generated. Furthermore, the linearly and circularly polarized photons in the optical and radio bands may suffer heavy absorptions from the slab. Thus we consider the polarized jitter radiation transfer processes. Finally, we compare our model results with the optical detections of GRB 091018, GRB 121024A, and GRB 131030A. We suggest simultaneous observations of GRB multi-wavelength polarization in the future.

  13. Vibrational tug-of-war: The pKA dependence of the broad vibrational features of strongly hydrogen-bonded carboxylic acids

    Science.gov (United States)

    Van Hoozen, Brian L.; Petersen, Poul B.

    2018-04-01

    of strongly hydrogen-bonded structures depend on the relative pKA and other structural parameters will guide studies of biological structures and analysis of proton transfer studies using photoacids.

  14. Excision Efficiency Is Not Strongly Coupled to Transgenic Rate: Cell Type-Dependent Transposition Efficiency of Sleeping Beauty and piggyBac DNA Transposons

    Science.gov (United States)

    Kolacsek, Orsolya; Erdei, Zsuzsa; Apáti, Ágota; Sándor, Sára; Izsvák, Zsuzsanna; Ivics, Zoltán; Sarkadi, Balázs

    2014-01-01

    Abstract The Sleeping Beauty (SB) and piggyBac (PB) DNA transposons represent an emerging new gene delivery technology, potentially suitable for human gene therapy applications. Previous studies pointed to important differences between these transposon systems, depending on the cell types examined and the methodologies applied. However, efficiencies cannot always be compared because of differences in applications. In addition, “overproduction inhibition,” a phenomenon believed to be a characteristic of DNA transposons, can remarkably reduce the overall transgenic rate, emphasizing the importance of transposase dose applied. Therefore, because of lack of comprehensive analysis, researchers are forced to optimize the technology for their own “in-house” platforms. In this study, we investigated the transposition of several SB (SB11, SB32, SB100X) and PB (mPB and hyPB) variants in various cell types at three levels: comparing the excision efficiency of the reaction by real-time PCR, testing the overall transgenic rate by detecting cells with stable integrations, and determining the average copy number when using different transposon systems and conditions. We concluded that high excision activity is not always followed by a higher transgenic rate, as exemplified by the hyperactive transposases, indicating that the excision and the integration steps of transposition are not strongly coupled as previously thought. In general, all levels of transposition show remarkable differences depending on the transposase used and cell lines examined, being the least efficient in human embryonic stem cells (hESCs). In spite of the comparably low activity in those special cell types, the hyperactive SB100X and hyPB systems could be used in hESCs with similar transgenic efficiency and with reasonably low (2–3) transgene copy numbers, indicating their potential applicability for gene therapy purposes in the future. PMID:25045962

  15. A chemo-mechanical free-energy-based approach to model durotaxis and extracellular stiffness-dependent contraction and polarization of cells.

    Science.gov (United States)

    Shenoy, Vivek B; Wang, Hailong; Wang, Xiao

    2016-02-06

    We propose a chemo-mechanical model based on stress-dependent recruitment of myosin motors to describe how the contractility, polarization and strain in cells vary with the stiffness of their surroundings and their shape. A contractility tensor, which depends on the distribution of myosin motors, is introduced to describe the chemical free energy of the cell due to myosin recruitment. We explicitly include the contributions to the free energy that arise from mechanosensitive signalling pathways (such as the SFX, Rho-Rock and MLCK pathways) through chemo-mechanical coupling parameters. Taking the variations of the total free energy, which consists of the chemical and mechanical components, in accordance with the second law of thermodynamics provides equations for the temporal evolution of the active stress and the contractility tensor. Following this approach, we are able to recover the well-known Hill relation for active stresses, based on the fundamental principles of irreversible thermodynamics rather than phenomenology. We have numerically implemented our free energy-based approach to model spatial distribution of strain and contractility in (i) cells supported by flexible microposts, (ii) cells on two-dimensional substrates, and (iii) cells in three-dimensional matrices. We demonstrate how the polarization of the cells and the orientation of stress fibres can be deduced from the eigenvalues and eigenvectors of the contractility tensor. Our calculations suggest that the chemical free energy of the cell decreases with the stiffness of the extracellular environment as the cytoskeleton polarizes in response to stress-dependent recruitment of molecular motors. The mechanical energy, which includes the strain energy and motor potential energy, however, increases with stiffness, but the overall energy is lower for cells in stiffer environments. This provides a thermodynamic basis for durotaxis, whereby cells preferentially migrate towards stiffer regions of the

  16. Carbon dots with strong excitation-dependent fluorescence changes towards pH. Application as nanosensors for a broad range of pH.

    Science.gov (United States)

    Barati, Ali; Shamsipur, Mojtaba; Abdollahi, Hamid

    2016-08-10

    In this study, preparation of novel pH-sensitive N-doped carbon dots (NCDs) using glucose and urea is reported. The prepared NCDs present strong excitation-dependent fluorescence changes towards the pH that is a new behavior from these nanomaterials. By taking advantage of this unique behavior, two separated ratiometric pH sensors using emission spectra of the NCDs for both acidic (pH 2.0 to 8.0) and basic (pH 7.0 to 14.0) ranges of pH are constructed. Additionally, by considering the entire Excitation-Emission Matrix (EEM) of NCDs as analytical signal and using a suitable multivariate calibration method, a broad range of pH from 2.0 to 14.0 was well calibrated. The multivariate calibration method was independent from the concentration of NCDs and resulted in a very low average prediction error of 0.067 pH units. No changes in the predicted pH under UV irradiation (for 3 h) and at high ionic strength (up to 2 M NaCl) indicated the high stability of this pH nanosensor. The practicality of this pH nanosensor for pH determination in real water samples was validated with good accuracy and repeatability. Copyright © 2016 Elsevier B.V. All rights reserved.

  17. Hormonal regulation of gluconeogenesis in cereal aleurone is strongly cultivar-dependent and gibberellin action involves SLENDER1 but not GAMYB.

    Science.gov (United States)

    Eastmond, Peter J; Jones, Russell L

    2005-11-01

    Storage oil is a major constituent in the cereal aleurone layer. The aim of this study was to investigate how gibberellin (GA) and abscisic acid (ABA) regulate conversion of oil to sugar in barley aleurone. The activity of the glyoxylate cycle enzyme isocitrate lyase (ICL) was surveyed in eight barley cultivars. Surprisingly, some cultivars do not require GA for the induction of ICL (e.g. Himalaya), whereas some do (e.g. Golden Promise). Furthermore, in Golden Promise, GA also stimulates triacylglycerol breakdown and enhances the net flux of carbon from acetate to sugar. In contrast, ABA strongly represses ICL activity and the flux of carbon from oil to sugar in both Golden Promise and Himalaya. Biolistics using a promoter reporter showed that GA and ABA regulate ICL at the level of transcription. Studies using barley and rice mutants and pharmacological agents show that GA-dependent induction of ICL activity is mediated by SLENDER1 and requires cGMP, but does not involve the transcription factor GAMYB. Gibberellin and ABA therefore act antagonistically to regulate gluconeogenesis in the aleurone layer as well as controlling the production and secretion of hydrolases into the starchy endosperm. We suggest that the variation between different barley cultivars might be a result of selective breeding to alter seed dormancy.

  18. Effect of delayed link failure on probability of loss of assured safety in temperature-dependent systems with multiple weak and strong links.

    Energy Technology Data Exchange (ETDEWEB)

    Johnson, J. D. (ProStat, Mesa, AZ); Oberkampf, William Louis; Helton, Jon Craig (Arizona State University, Tempe, AZ)

    2007-05-01

    Weak link (WL)/strong link (SL) systems constitute important parts of the overall operational design of high consequence systems, with the SL system designed to permit operation of the system only under intended conditions and the WL system designed to prevent the unintended operation of the system under accident conditions. Degradation of the system under accident conditions into a state in which the WLs have not deactivated the system and the SLs have failed in the sense that they are in a configuration that could permit operation of the system is referred to as loss of assured safety. The probability of such degradation conditional on a specific set of accident conditions is referred to as probability of loss of assured safety (PLOAS). Previous work has developed computational procedures for the calculation of PLOAS under fire conditions for a system involving multiple WLs and SLs and with the assumption that a link fails instantly when it reaches its failure temperature. Extensions of these procedures are obtained for systems in which there is a temperature-dependent delay between the time at which a link reaches its failure temperature and the time at which that link actually fails.

  19. Next-to-leading order corrections to the spin-dependent energy spectrum of hadrons from polarized top quark decay in the general two Higgs doublet model

    Directory of Open Access Journals (Sweden)

    S. Mohammad Moosavi Nejad

    2017-08-01

    Full Text Available In recent years, searches for the light and heavy charged Higgs bosons have been done by the ATLAS and the CMS collaborations at the Large Hadron Collider (LHC in proton–proton collision. Nevertheless, a definitive search is a program that still has to be carried out at the LHC. The experimental observation of charged Higgs bosons would indicate physics beyond the Standard Model. In the present work, we study the scaled-energy distribution of bottom-flavored mesons (B inclusively produced in polarized top quark decays into a light charged Higgs boson and a massless bottom quark at next-to-leading order in the two-Higgs-doublet model; t(↑→bH+→BH++X. This spin-dependent energy distribution is studied in a specific helicity coordinate system where the polarization vector of the top quark is measured with respect to the direction of the Higgs momentum. The study of these energy distributions could be considered as a new channel to search for the charged Higgs bosons at the LHC. For our numerical analysis and phenomenological predictions, we restrict ourselves to the unexcluded regions of the MSSM mH+−tan⁡β parameter space determined by the recent results of the CMS [13] and ATLAS [14] collaborations.

  20. Slot-dimer babinet metamaterials as polarization shapers for terahertz waves

    DEFF Research Database (Denmark)

    Zhukovsky, Sergei; Chigrin, D. N.; Lavrinenko, Andrei

    2013-01-01

    We theoretically study optical properties of free-standing metallic membranes patterned with an array of two-slot elements (dimers) comprising two rectangular slots of different dimensions and orientation. It is shown that these structures feature extraordinary optical transmission with strong...... and spectrally selective polarization conversion capabilities. The output polarization is highly dependent on the dimer geometry, which can be used in the design of compact polarization shapers for terahertz waves....

  1. Spin and Angular Momentum in Strong-Field Ionization

    Science.gov (United States)

    Trabert, D.; Hartung, A.; Eckart, S.; Trinter, F.; Kalinin, A.; Schöffler, M.; Schmidt, L. Ph. H.; Jahnke, T.; Kunitski, M.; Dörner, R.

    2018-01-01

    The spin polarization of electrons from multiphoton ionization of Xe by 395 nm circularly polarized laser pulses at 6 ×1013 W /cm2 has been measured. At this photon energy of 3.14 eV the above-threshold ionization peaks connected to Xe+ ions in the ground state (J =3 /2 , ionization potential Ip=12.1 eV ) and the first excited state (J =1 /2 , Ip=13.4 eV ) are clearly separated in the electron energy distribution. These two combs of above-threshold ionization peaks show opposite spin polarizations. The magnitude of the spin polarization is a factor of 2 higher for the J =1 /2 than for the J =3 /2 final ionic state. In turn, the data show that the ionization probability is strongly dependent on the sign of the magnetic quantum number.

  2. Portable ultrahigh-vacuum sample storage system for polarization-dependent total-reflection fluorescence x-ray absorption fine structure spectroscopy

    Energy Technology Data Exchange (ETDEWEB)

    Watanabe, Yoshihide, E-mail: e0827@mosk.tytlabs.co.jp; Nishimura, Yusaku F.; Suzuki, Ryo; Beniya, Atsushi; Isomura, Noritake [Toyota Central R& D Labs., Inc., Yokomichi 41-1, Nagakute, Aichi 480-1192 (Japan); Uehara, Hiromitsu; Asakura, Kiyotaka; Takakusagi, Satoru [Catalysis Research Center, Hokkaido University, Kita 21-10, Sapporo, Hokkaido 001-0021 (Japan); Nimura, Tomoyuki [AVC Co., Ltd., Inada 1450-6, Hitachinaka, Ibaraki 312-0061 (Japan)

    2016-03-15

    A portable ultrahigh-vacuum sample storage system was designed and built to investigate the detailed geometric structures of mass-selected metal clusters on oxide substrates by polarization-dependent total-reflection fluorescence x-ray absorption fine structure spectroscopy (PTRF-XAFS). This ultrahigh-vacuum (UHV) sample storage system provides the handover of samples between two different sample manipulating systems. The sample storage system is adaptable for public transportation, facilitating experiments using air-sensitive samples in synchrotron radiation or other quantum beam facilities. The samples were transferred by the developed portable UHV transfer system via a public transportation at a distance over 400 km. The performance of the transfer system was demonstrated by a successful PTRF-XAFS study of Pt{sub 4} clusters deposited on a TiO{sub 2}(110) surface.

  3. Collective effects in spin polarized plasmas

    International Nuclear Information System (INIS)

    Coppi, B.; Cowley, S.; Detragiache, P.; Kulsrud, R.; Pegoraro, F.

    1984-10-01

    A fusing plasma with coherently polarized spin nuclei can be subject to instabilities due to the anisotropy of the reaction product distributions in velocity space, which is a result of their polarization. The characteristics of these instabilities depend strongly on the plasma spatial inhomogeneities and a significant rate of spin depolarization can be produced by them if adequate fluctuation amplitudes are reached. The results of the relevant analysis are, in addition, of interest for plasma heating processes with frequencies in the range of the cyclotron frequencies of the considered nuclei

  4. Endogenous proteolytic cleavage of disease-associated prion protein to produce C2 fragments is strongly cell- and tissue-dependent.

    Science.gov (United States)

    Dron, Michel; Moudjou, Mohammed; Chapuis, Jérôme; Salamat, Muhammad Khalid Farooq; Bernard, Julie; Cronier, Sabrina; Langevin, Christelle; Laude, Hubert

    2010-04-02

    The abnormally folded form of the prion protein (PrP(Sc)) accumulating in nervous and lymphoid tissues of prion-infected individuals can be naturally cleaved to generate a N-terminal-truncated fragment called C2. Information about the identity of the cellular proteases involved in this process and its possible role in prion biology has remained limited and controversial. We investigated PrP(Sc) N-terminal trimming in different cell lines and primary cultured nerve cells, and in the brain and spleen tissue from transgenic mice infected by ovine and mouse prions. We found the following: (i) the full-length to C2 ratio varies considerably depending on the infected cell or tissue. Thus, in primary neurons and brain tissue, PrP(Sc) accumulated predominantly as untrimmed species, whereas efficient trimming occurred in Rov and MovS cells, and in spleen tissue. (ii) Although C2 is generally considered to be the counterpart of the PrP(Sc) proteinase K-resistant core, the N termini of the fragments cleaved in vivo and in vitro can actually differ, as evidenced by a different reactivity toward the Pc248 anti-octarepeat antibody. (iii) In lysosome-impaired cells, the ratio of full-length versus C2 species dramatically increased, yet efficient prion propagation could occur. Moreover, cathepsin but not calpain inhibitors markedly inhibited C2 formation, and in vitro cleavage by cathepsins B and L produced PrP(Sc) fragments lacking the Pc248 epitope, strongly arguing for the primary involvement of acidic hydrolases of the endolysosomal compartment. These findings have implications on the molecular analysis of PrP(Sc) and cell pathogenesis of prion infection.

  5. Endogenous Proteolytic Cleavage of Disease-associated Prion Protein to Produce C2 Fragments Is Strongly Cell- and Tissue-dependent*

    Science.gov (United States)

    Dron, Michel; Moudjou, Mohammed; Chapuis, Jérôme; Salamat, Muhammad Khalid Farooq; Bernard, Julie; Cronier, Sabrina; Langevin, Christelle; Laude, Hubert

    2010-01-01

    The abnormally folded form of the prion protein (PrPSc) accumulating in nervous and lymphoid tissues of prion-infected individuals can be naturally cleaved to generate a N-terminal-truncated fragment called C2. Information about the identity of the cellular proteases involved in this process and its possible role in prion biology has remained limited and controversial. We investigated PrPSc N-terminal trimming in different cell lines and primary cultured nerve cells, and in the brain and spleen tissue from transgenic mice infected by ovine and mouse prions. We found the following: (i) the full-length to C2 ratio varies considerably depending on the infected cell or tissue. Thus, in primary neurons and brain tissue, PrPSc accumulated predominantly as untrimmed species, whereas efficient trimming occurred in Rov and MovS cells, and in spleen tissue. (ii) Although C2 is generally considered to be the counterpart of the PrPSc proteinase K-resistant core, the N termini of the fragments cleaved in vivo and in vitro can actually differ, as evidenced by a different reactivity toward the Pc248 anti-octarepeat antibody. (iii) In lysosome-impaired cells, the ratio of full-length versus C2 species dramatically increased, yet efficient prion propagation could occur. Moreover, cathepsin but not calpain inhibitors markedly inhibited C2 formation, and in vitro cleavage by cathepsins B and L produced PrPSc fragments lacking the Pc248 epitope, strongly arguing for the primary involvement of acidic hydrolases of the endolysosomal compartment. These findings have implications on the molecular analysis of PrPSc and cell pathogenesis of prion infection. PMID:20154089

  6. Sensitivity of Helicobacter pylori detection by Giemsa staining is poor in comparison with immunohistochemistry and fluorescent in situ hybridization and strongly depends on inflammatory activity.

    Science.gov (United States)

    Kocsmár, Éva; Szirtes, Ildikó; Kramer, Zsófia; Szijártó, Attila; Bene, László; Buzás, György Miklós; Kenessey, István; Bronsert, Peter; Csanadi, Agnes; Lutz, Lisa; Werner, Martin; Wellner, Ulrich Friedrich; Kiss, András; Schaff, Zsuzsa; Lotz, Gábor

    2017-08-01

    Conventional stainings (including H&E and special stains like Giemsa) are the most widely applied histopathologic detection methods of Helicobacter pylori (HP). We aimed to compare the diagnostic performance of Giemsa staining with immunohistochemistry (IHC) and fluorescent in situ hybridization (FISH) on a monocentric cohort of 2896 gastric biopsies and relate results to histologic alterations in order to find such histopathologic subgroups in which these methods underperform. All cases were categorized regarding presence or absence of chronic gastritis, inflammatory activity, and mucosal structural alterations. Giemsa revealed 687 cases (23.7%), IHC 795 cases (27.5%), and FISH 788 cases (27.2%) as being HP positive. Giemsa showed significantly lower overall sensitivity (83.3%) compared to IHC (98.8%) and FISH (98.0%). Moreover, the sensitivity of Giemsa dramatically dropped to 33.6% in the nonactive cases. We found that sensitivity of Giemsa strongly depends on HP density and, accordingly, on the presence of activity. Structural alterations (intestinal metaplasia, atrophy, etc.) had only no or weak effect on sensitivity of the three stainings. Both IHC and FISH proved to be equally reliable HP detecting techniques whose diagnostic performance is minimally influenced by mucosal inflammatory and structural alterations contrary to conventional stainings. We highly recommend immunohistochemistry for clinically susceptible, nonactive chronic gastritis cases, if the conventional stain-based HP detection is negative. Moreover, we recommend to use IHC more widely as basic HP stain. Helicobacter pylori FISH technique is primarily recommended to determine bacterial clarithromycin resistance. Furthermore, it is another accurate diagnostic tool for HP. © 2017 John Wiley & Sons Ltd.

  7. Airborne Laser Polarization Sensor

    Science.gov (United States)

    Kalshoven, James, Jr.; Dabney, Philip

    1991-01-01

    Instrument measures polarization characteristics of Earth at three wavelengths. Airborne Laser Polarization Sensor (ALPS) measures optical polarization characteristics of land surface. Designed to be flown at altitudes of approximately 300 m to minimize any polarizing or depolarizing effects of intervening atmosphere and to look along nadir to minimize any effects depending on look angle. Data from measurements used in conjunction with data from ground surveys and aircraft-mounted video recorders to refine mathematical models used in interpretation of higher-altitude polarimetric measurements of reflected sunlight.

  8. Lattice dynamics approach to determine the dependence of the time-of-flight of transversal polarized acoustic waves on external stress

    Science.gov (United States)

    Tarar, K. S.; Pluta, M.; Amjad, U.; Grill, W.

    2011-04-01

    Based on the lattice dynamics approach the dependence of the time-of-flight (TOF) on stress has been modeled for transversal polarized acoustic waves. The relevant dispersion relation is derived from the appropriate mass-spring model together with the dependencies on the restoring forces including the effect of externally applied stress. The lattice dynamics approach can also be interpreted as a discrete and strictly periodic lumped circuit. In that case the modeling represents a finite element approach. In both cases the properties relevant for wavelengths large with respect to the periodic structure can be derived from the respective limit relating also to low frequencies. The model representing a linear chain with stiffness to shear and additional stiffness introduced by extensional stress is presented and compared to existing models, which so far represent each only one of the effects treated here in combination. For a string this effect is well known from musical instruments. The counteracting effects are discussed and compared to experimental results.

  9. Two-Photon Polarization Dependent Spectroscopy in Chirality: A Novel Experimental-Theoretical Approach to Study Optically Active Systems

    Directory of Open Access Journals (Sweden)

    Florencio E. Hernández

    2011-04-01

    Full Text Available Many phenomena, including life itself and its biochemical foundations are fundamentally rooted in chirality. Combinatorial methodologies for catalyst discovery and optimization remain an invaluable tool for gaining access to enantiomerically pure compounds in the development of pharmaceuticals, agrochemicals, and flavors. Some exotic metamaterials exhibiting negative refractive index at optical frequencies are based on chiral structures. Chiroptical activity is commonly quantified in terms of circular dichroism (CD and optical rotatory dispersion (ORD. However, the linear nature of these effects limits their application in the far and near-UV region in highly absorbing and scattering biological systems. In order to surmount this barrier, in recent years we made important advancements on a novel non linear, low-scatter, long-wavelength CD approach called two-photon absorption circular dichroism (TPACD. Herein we present a descriptive analysis of the optics principles behind the experimental measurement of TPACD, i.e., the double L-scan technique, and its significance using pulsed lasers. We also make an instructive examination and discuss the reliability of our theoretical-computational approach, which uses modern analytical response theory, within a Time-Dependent Density Functional Theory (TD-DFT approach. In order to illustrate the potential of this novel spectroscopic tool, we first present the experimental and theoretical results obtained in C2-symmetric, axially chiral R-(+-1,1'-bi(2-naphthol, R-BINOL, a molecule studied at the beginning of our investigation in this field. Next, we reveal some preliminary results obtained for (R-3,3′-diphenyl-2,2′-bi-1-naphthol, R-VANOL, and (R-2,2′-diphenyl-3,3′-(4-biphenanthrol, R-VAPOL. This family of optically active compounds has been proven to be a suitable model for the structure-property relationship study of TPACD, because its members are highly conjugated yet photo-stable, and easily

  10. Unconventional superconductivity in cuprates, cobaltates and graphene. What is universal and what is material-dependent in strongly versus weakly correlated materials?

    International Nuclear Information System (INIS)

    Kiesel, Maximilian Ludwig

    2013-01-01

    A general theory for all classes of unconventional superconductors is still one of the unsolved key issues in condensed-matter physics. Actually, it is not yet fully settled if there is a common underlying pairing mechanism. Instead, it might be possible that several distinct sources for unconventional (not phonon-mediated) superconductivity have to be considered, or an electron-phonon interaction is not negligible. The focus of this thesis is on the most probable mechanism for the formation of Cooper pairs in unconventional superconductors, namely a strictly electronic one where spin fluctuations are the mediators. Studying different superconductors in this thesis, the emphasis is put on material-independent features of the pairing mechanism. In addition, the investigation of the phase diagrams enables a view on the vicinity of superconductivity. Thus, it is possible to clarify which competing quantum fluctuations enhance or weaken the propensity for a superconducting state. The broad range of superconducting materials requires the use of more than one numerical technique to study an appropriate microscopic description. This is not a problem but a big advantage because this facilitates the approach-independent description of common underlying physics. For this evaluation, the strongly correlated cuprates are simulated with the variational cluster approach. Especially the question of a pairing glue is taken into consideration. Furthermore, it is possible to distinguish between retarded and non-retarded contributions to the gap function. The cuprates are confronted with the cobaltate Na x CoO 2 and graphene. These weakly correlated materials are investigated with the functional renormalization group (fRG) and reveal a comprehensive phase diagram, including a d+id-wave superconductivity, which breaks time-reversal symmetry. The corresponding gap function is nodeless, but for NaCoO, it features a doping-dependent anisotropy. In addition, some general considerations on

  11. Unconventional superconductivity in cuprates, cobaltates and graphene. What is universal and what is material-dependent in strongly versus weakly correlated materials?

    Energy Technology Data Exchange (ETDEWEB)

    Kiesel, Maximilian Ludwig

    2013-02-08

    A general theory for all classes of unconventional superconductors is still one of the unsolved key issues in condensed-matter physics. Actually, it is not yet fully settled if there is a common underlying pairing mechanism. Instead, it might be possible that several distinct sources for unconventional (not phonon-mediated) superconductivity have to be considered, or an electron-phonon interaction is not negligible. The focus of this thesis is on the most probable mechanism for the formation of Cooper pairs in unconventional superconductors, namely a strictly electronic one where spin fluctuations are the mediators. Studying different superconductors in this thesis, the emphasis is put on material-independent features of the pairing mechanism. In addition, the investigation of the phase diagrams enables a view on the vicinity of superconductivity. Thus, it is possible to clarify which competing quantum fluctuations enhance or weaken the propensity for a superconducting state. The broad range of superconducting materials requires the use of more than one numerical technique to study an appropriate microscopic description. This is not a problem but a big advantage because this facilitates the approach-independent description of common underlying physics. For this evaluation, the strongly correlated cuprates are simulated with the variational cluster approach. Especially the question of a pairing glue is taken into consideration. Furthermore, it is possible to distinguish between retarded and non-retarded contributions to the gap function. The cuprates are confronted with the cobaltate Na{sub x}CoO{sub 2} and graphene. These weakly correlated materials are investigated with the functional renormalization group (fRG) and reveal a comprehensive phase diagram, including a d+id-wave superconductivity, which breaks time-reversal symmetry. The corresponding gap function is nodeless, but for NaCoO, it features a doping-dependent anisotropy. In addition, some general

  12. Alfvénic fluctuations in "newborn"' polar solar wind

    Directory of Open Access Journals (Sweden)

    B. Bavassano

    2005-06-01

    Full Text Available The 3-D structure of the solar wind is strongly dependent upon the Sun's activity cycle. At low solar activity a bimodal structure is dominant, with a fast and uniform flow at the high latitudes, and slow and variable flows at low latitudes. Around solar maximum, in sharp contrast, variable flows are observed at all latitudes. This last kind of pattern, however, is a relatively short-lived feature, and quite soon after solar maximum the polar wind tends to regain its role. The plasma parameter distributions for these newborn polar flows appear very similar to those typically observed in polar wind at low solar activity. The point addressed here is about polar wind fluctuations. As is well known, the low-solar-activity polar wind is characterized by a strong flow of Alfvénic fluctuations. Does this hold for the new polar flows too? An answer to this question is given here through a comparative statistical analysis on parameters such as total energy, cross helicity, and residual energy, that are of general use to describe the Alfvénic character of fluctuations. Our results indicate that the main features of the Alfvénic fluctuations observed in low-solar-activity polar wind have been quickly recovered in the new polar flows developed shortly after solar maximum. Keywords. Interplanetary physics (MHD waves and turbulence; Sources of the solar wind – Space plasma physics (Turbulence

  13. Polarization Diversity DPSK Demodulator on the Silicon-on-Insulator Platform with Simple Fabrication

    DEFF Research Database (Denmark)

    Ding, Yunhong; Huang, Bo; Ou, Haiyan

    2013-01-01

    We demonstrate a novel polarization diversity DPSK demodulator on the SOI platform with low polarization dependent loss (1.6 dB) and low polarization dependent extinction ratio (<3 dB). System experiments verify the low polarization dependency....

  14. A model of quasi-free scattering with polarized protons

    International Nuclear Information System (INIS)

    Teodoro, M.R.

    1976-01-01

    A quantitative evaluation, based on a simple model for spin-free coplanar and asymmetric reaction in 16 O, for 215 MeV incoming polarized protons confirms the use of the strong effective polarization of the knocked-out proton by the spin-orbit coupling and of the strong dependence of free, medium energy, proton-proton cross section on the relative orientation of the proton spins. Effective polarizations, momentum distributions and correlation cross sections have been calculated for the 1p sub(1/2), 1 p sub(3/2) and 1s sub(1/2) states in 16 O, using protons totally polarized orthogonal to the scattering plane. Harmonic oscillator and square wells have been used to generate the bound state wave functions, whereas the optical potentials have been taken spin-independent and purely imaginary [pt

  15. Circular polarization in a non-magnetic resonant tunneling device

    Directory of Open Access Journals (Sweden)

    Airey Robert

    2011-01-01

    Full Text Available Abstract We have investigated the polarization-resolved photoluminescence (PL in an asymmetric n-type GaAs/AlAs/GaAlAs resonant tunneling diode under magnetic field parallel to the tunnel current. The quantum well (QW PL presents strong circular polarization (values up to -70% at 19 T. The optical emission from GaAs contact layers shows evidence of highly spin-polarized two-dimensional electron and hole gases which affects the spin polarization of carriers in the QW. However, the circular polarization degree in the QW also depends on various other parameters, including the g-factors of the different layers, the density of carriers along the structure, and the Zeeman and Rashba effects.

  16. Micromagnetic investigation of the dynamics of magnetization switching induced by a spin polarized current

    Science.gov (United States)

    Lee, Kyung-Jin; Dieny, Bernard

    2006-03-01

    Using micromagnetic modeling, we tested a prediction of single-domain spin-torque theory which switching current density depends only weakly on magnetic cell size. The switching time and current density are strongly affected by the cell size for low spin polarization. Larger samples with a small length-to-width ratio and small spin polarization can exhibit a nonmonotonous dependence of switching time on current. Excitation of incoherent spin waves caused by the circular Oersted field due to the current is responsible for this nonmonotonous dependence. However, the magnetic dynamics recovers a single-domain-like behavior when the spin polarization is high and/or the cell size is small.

  17. Spin-Polarized Semiconductor Induced by Magnetic Impurities in Graphene

    OpenAIRE

    Daghofer, Maria; Zheng, Nan; Moreo, Adriana

    2010-01-01

    Magnetic impurities adsorbed on graphene are coupled magnetically via the itinerant electrons. This interaction opens a gap in the band structure of graphene. The result strongly depends on how the magnetic impurities are distributed. While random doping produces a semiconductor, if all or most impurities are located in the same sublattice, the spin degeneracy is removed and a spin-polarized semiconductor arises.

  18. Interpretation of the Global Anisotropy in the Radio Polarizations of ...

    Indian Academy of Sciences (India)

    data. We also find that a generalized statistic shows a very strong signal in the entire data without imposing the RM dependent cut. Finally we argue that an anisotropic background ... high-redshift—cosmology: miscellaneous—elementary particles. 1. .... Statistical analysis of the angular correlation in polarizations. We next ...

  19. Polarized Raman spectroscopy of chemically vapour deposited diamond films

    International Nuclear Information System (INIS)

    Prawer, S.; Nugent, K.W.; Weiser, P.S.

    1994-01-01

    Polarized micro-Raman spectra of chemically vapour deposited diamond films are presented. It is shown that important parameters often extracted from the Raman spectra such as the ratio of the diamond to non-diamond component of the films and the estimation of the level of residual stress depend on the orientation of the diamond crystallites with respect to the polarization of the incident laser beam. The dependence originates from the fact that the Raman scattering from the non-diamond components in the films is almost completely depolarized whilst the scattering from the diamond components is strongly polarized. The results demonstrate the importance of taking polarization into account when attempting to use Raman spectroscopy in even a semi-quantitative fashion for the assessment of the purity, perfection and stress in CVD diamond films. 8 refs., 1 tab. 2 figs

  20. Solar Illumination Control of the Polar Wind

    Science.gov (United States)

    Maes, L.; Maggiolo, R.; De Keyser, J.; André, M.; Eriksson, A. I.; Haaland, S.; Li, K.; Poedts, S.

    2017-11-01

    Polar wind outflow is an important process through which the ionosphere supplies plasma to the magnetosphere. The main source of energy driving the polar wind is solar illumination of the ionosphere. As a result, many studies have found a relation between polar wind flux densities and solar EUV intensity, but less is known about their relation to the solar zenith angle at the ionospheric origin, certainly at higher altitudes. The low energy of the outflowing particles and spacecraft charging means it is very difficult to measure the polar wind at high altitudes. We take advantage of an alternative method that allows estimations of the polar wind flux densities far in the lobes. We analyze measurements made by the Cluster spacecraft at altitudes from 4 up to 20 RE. We observe a strong dependence on the solar zenith angle in the ion flux density and see that both the ion velocity and density exhibit a solar zenith angle dependence as well. We also find a seasonal variation of the flux density.

  1. Polarization measurement of laser-accelerated protons

    Energy Technology Data Exchange (ETDEWEB)

    Raab, Natascha; Engels, Ralf; Engin, Ilhan; Greven, Patrick; Holler, Astrid; Lehrach, Andreas; Maier, Rudolf [Institut für Kernphysik and Jülich Center for Hadron Physics, Forschungszentrum Jülich, 52425 Jülich (Germany); Büscher, Markus, E-mail: m.buescher@fz-juelich.de [Institut für Kernphysik and Jülich Center for Hadron Physics, Forschungszentrum Jülich, 52425 Jülich (Germany); Peter Grünberg Institut (PGI-6), Forschungszentrum Jülich, 52425 Jülich (Germany); Institute for Laser- and Plasma Physics, Heinrich-Heine Universität Düsseldorf, Universitätsstr. 1, 40225 Düsseldorf (Germany); Cerchez, Mirela; Swantusch, Marco; Toncian, Monika; Toncian, Toma; Willi, Oswald [Institute for Laser- and Plasma Physics, Heinrich-Heine Universität Düsseldorf, Universitätsstr. 1, 40225 Düsseldorf (Germany); Gibbon, Paul; Karmakar, Anupam [Institute for Advanced Simulation, Jülich Supercomputing Centre, Forschungszentrum Jülich, 52425 Jülich (Germany)

    2014-02-15

    We report on the successful use of a laser-driven few-MeV proton source to measure the differential cross section of a hadronic scattering reaction as well as on the measurement and simulation study of polarization observables of the laser-accelerated charged particle beams. These investigations were carried out with thin foil targets, illuminated by 100 TW laser pulses at the Arcturus laser facility; the polarization measurement is based on the spin dependence of hadronic proton scattering off nuclei in a Silicon target. We find proton beam polarizations consistent with zero magnitude which indicates that for these particular laser-target parameters the particle spins are not aligned by the strong magnetic fields inside the laser-generated plasmas.

  2. Spectral dependence of backscattering coefficient of mixed phase clouds over West Africa measured with two-wavelength Raman polarization lidar: Features attributed to ice-crystals corner reflection

    Science.gov (United States)

    Veselovskii, I.; Goloub, P.; Podvin, T.; Tanre, D.; Ansmann, A.; Korenskiy, M.; Borovoi, A.; Hu, Q.; Whiteman, D. N.

    2017-11-01

    The existing models predict that corner reflection (CR) of laser radiation by simple ice crystals of perfect shape, such as hexagonal columns or plates, can provide a significant contribution to the ice cloud backscattering. However in real clouds the CR effect may be suppressed due to crystal deformation and surface roughness. In contrast to the extinction coefficient, which is spectrally independent, consideration of diffraction associated with CR results in a spectral dependence of the backscattering coefficient. Thus measuring the spectral dependence of the cloud backscattering coefficient, the contribution of CR can be identified. The paper presents the results of profiling of backscattering coefficient (β) and particle depolarization ratio (δ) of ice and mixed-phase clouds over West Africa by means of a two-wavelength polarization Mie-Raman lidar operated at 355 nm and 532 nm during the SHADOW field campaign. The lidar observations were performed at a slant angle of 43 degree off zenith, thus CR from both randomly oriented crystals and oriented plates could be analyzed. For the most of the observations the cloud backscatter color ratio β355/β532 was close to 1.0, and no spectral features that might indicate the presence of CR of randomly oriented crystals were revealed. Still, in two measurement sessions we observed an increase of backscatter color ratio to a value of nearly 1.3 simultaneously with a decrease of the spectral depolarization ratio δ355/δ532 ratio from 1.0 to 0.8 inside the layers containing precipitating ice crystals. We attribute these changes in optical properties to corner reflections by horizontally oriented ice plates.

  3. Peculiarities of spin polarization inversion at a thiophene/cobalt interface

    KAUST Repository

    Wang, Xuhui

    2013-03-20

    We perform ab initio calculations to investigate the spin polarization at the interface between a thiophene molecule and cobalt substrate. We find that the reduced symmetry in the presence of a sulfur atom (in the thiophene molecule) leads to a strong spatial dependence of the spin polarization of the molecule. The two carbon atoms far from the sulfur acquire a polarization opposite to that of the substrate, while the carbon atoms bonded directly to sulfur possess the same polarization as the substrate. We determine the origin of this peculiar spin interface property as well as its impact on the spin transport.

  4. Measurement of inclusive quasielastic scattering of polarized electrons from polarized 3He

    International Nuclear Information System (INIS)

    Woodward, C.E.; Beise, E.J.; Belz, J.E.; Carr, R.W.; Filippone, B.W.; Lorenzon, W.B.; McKeown, R.D.; Mueller, B.; O'Neill, T.G.; Dodson, G.; Dow, K.; Farkhondeh, M.; Kowalski, S.; Lee, K.; Makins, N.; Milner, R.; Thompson, A.; Tieger, D.; van den Brand, J.; Young, A.; Yu, X.; Zumbro, J.

    1990-01-01

    We report a measurement of the asymmetry in spin-dependent quasielastic scattering of longitudinally polarized electrons from a polarized 3 He gas target. This measurement represents the first demonstration of a new method for studying electromagnetic nuclear structure: the scattering of polarized electrons from a polarized nuclear target. The measured asymmetry is in good agreement with a Faddeev calculation and supports the picture of spin-dependent quasielastic scattering from polarized 3 He as predominantly scattering from a polarized neutron

  5. Precision Polarization of Neutrons

    Science.gov (United States)

    Martin, Elise; Barron-Palos, Libertad; Couture, Aaron; Crawford, Christopher; Chupp, Tim; Danagoulian, Areg; Estes, Mary; Hona, Binita; Jones, Gordon; Klein, Andi; Penttila, Seppo; Sharma, Monisha; Wilburn, Scott

    2009-05-01

    Determining polarization of a cold neutron beam to high precision is required for the next generation neutron decay correlation experiments at the SNS, such as the proposed abBA and PANDA experiments. Precision polarimetry measurements were conducted at Los Alamos National Laboratory with the goal of determining the beam polarization to the level of 10-3 or better. The cold neutrons from FP12 were polarized using optically polarized ^3He gas as a spin filter, which has a highly spin-dependent absorption cross section. A second ^ 3He spin filter was used to analyze the neutron polarization after passing through a resonant RF spin rotator. A discussion of the experiment and results will be given.

  6. The grain size dependency of vesicular particle shapes strongly affects the drag of particles. First results from microtomography investigations of Campi Flegrei fallout deposits

    Science.gov (United States)

    Mele, Daniela; Dioguardi, Fabio

    2018-03-01

    Acknowledging the grain size dependency of shape is important in volcanology, in particular when dealing with tephra produced and emplaced during and after explosive volcanic eruptions. A systematic measurement of the tridimensional shape of vesicular pyroclasts of Campi Flegrei fallout deposits (Agnano-Monte Spina, Astroni 6 and Averno 2 eruptions) varying in size from 8.00 to 0.016 mm has been carried out by means of X-Ray Microtomography. Data show that particle shape changes with size, especially for juvenile vesicular clasts, since it is dependent on the distribution and size of vesicles that contour the external clast outline. Two drag laws that include sphericity in the formula were used for estimating the dependency of settling velocity on shape. Results demonstrate that it is not appropriate to assume a size-independent shape for vesicular particles, in contrast with the approach commonly employed when simulating the ash dispersion in the atmosphere.

  7. Outcome of Treatment of Human HeLa Cervical Cancer Cells With Roscovitine Strongly Depends on the Dosage and Cell Cycle Status Prior to the Treatment

    Czech Academy of Sciences Publication Activity Database

    Wesierska-Gadek, J.; Borza, A.; Walzi, E.; Kryštof, Vladimír; Maurer, M.; Komina, O.; Wandl, S.

    2009-01-01

    Roč. 106, č. 5 (2009), s. 937-955 ISSN 0730-2312 Institutional research plan: CEZ:AV0Z50380511 Keywords : APOPTOSIS * CELL CYCLE ARREST * CYCLIN-DEPENDENT KINASES Subject RIV: ED - Physiology Impact factor: 2.935, year: 2009

  8. Exploring the entrance of proton pathways in cytochrome c oxidase from Paracoccus denitrificans: surface charge, buffer capacity and redox-dependent polarity changes at the internal surface.

    Science.gov (United States)

    Kirchberg, Kristina; Michel, Hartmut; Alexiev, Ulrike

    2013-03-01

    Cytochrome c oxidase (CcO), the terminal oxidase of cellular respiration, reduces molecular oxygen to water. The mechanism of proton pumping as well as the coupling of proton and electron transfer is still not understood in this redox-linked proton pump. Eleven residues at the aqueous-exposed surfaces of CcO from Paracoccus denitrificans have been exchanged to cysteines in a two-subunit base variant to yield single reactive cysteine variants. These variants are designed to provide unique labeling sites for probes to be used in spectroscopic experiments investigating the mechanism of proton pumping in CcO. To this end we have shown that all cysteine variants are enzymatically active. Cysteine positions at the negative (N-) side of the membrane are located close to the entrance of the D- and K-proton transfer pathways that connect the N-side with the catalytic oxygen reduction site. Labeling of the pH-indicator dye fluorescein to these sites allowed us to determine the surface potential at the cytoplasmic CcO surface, which corresponds to a surface charge density of -0.5 elementary charge/1000Å(2). In addition, acid-base titrations revealed values of CcO buffer capacity. Polarity measurements of the label environment at the N-side provided (i) site-specific values indicative of a hydrophilic and a more hydrophobic environment dependent on the label position, and (ii) information on a global change to a more apolar environment upon reduction of the enzyme. Thus, the redox state of the copper and heme centers inside the hydrophobic interior of CcO affect the properties at the cytoplasmic surface. Copyright © 2012 Elsevier B.V. All rights reserved.

  9. Ehrenfest's theorem and the validity of the two-step model for strong-field ionization

    DEFF Research Database (Denmark)

    Shvetsov-Shilovskiy, Nikolay; Dimitrovski, Darko; Madsen, Lars Bojer

    By comparison with the solution of the time-dependent Schrodinger equation we explore the validity of the two-step semiclassical model for strong-field ionization in elliptically polarized laser pulses. We find that the discrepancy between the two-step model and the quantum theory correlates...

  10. Solvent Dependence of (14)N Nuclear Magnetic Resonance Chemical Shielding Constants as a Test of the Accuracy of the Computed Polarization of Solute Electron Densities by the Solvent.

    Science.gov (United States)

    Ribeiro, Raphael F; Marenich, Aleksandr V; Cramer, Christopher J; Truhlar, Donald G

    2009-09-08

    Although continuum solvation models have now been shown to provide good quantitative accuracy for calculating free energies of solvation, questions remain about the accuracy of the perturbed solute electron densities and properties computed from them. Here we examine those questions by applying the SM8, SM8AD, SMD, and IEF-PCM continuum solvation models in combination with the M06-L density functional to compute the (14)N magnetic resonance nuclear shieldings of CH3CN, CH3NO2, CH3NCS, and CH3ONO2 in multiple solvents, and we analyze the dependence of the chemical shifts on solvent dielectric constant. We examine the dependence of the computed chemical shifts on the definition of the molecular cavity (both united-atom models and models based on superposed individual atomic spheres) and three kinds of treatments of the electrostatics, namely the generalized Born approximation with the Coulomb field approximation, the generalized Born model with asymmetric descreening, and models based on approximate numerical solution schemes for the nonhomogeneous Poisson equation. Our most systematic analyses are based on the computation of relative (14)N chemical shifts in a series of solvents, and we compare calculated shielding constants relative to those in CCl4 for various solvation models and density functionals. While differences in the overall results are found to be reasonably small for different solvation models and functionals, the SMx models SM8, and SM8AD, using the same cavity definitions (which for these models means the same atomic radii) as those employed for the calculation of free energies of solvation, exhibit the best agreement with experiment for every functional tested. This suggests that in addition to predicting accurate free energies of solvation, the SM8 and SM8AD generalized Born models also describe the solute polarization in a manner reasonably consistent with experimental (14)N nuclear magnetic resonance spectroscopy. Models based on the

  11. Polarization fluctuations in stationary light beams

    International Nuclear Information System (INIS)

    Shevchenko, A.; Setaelae, T.; Kaivola, M.; Friberg, A.T.; Royal Institute of Technology , Department of Microelectronics and Applied Physics; Sweden)

    2009-01-01

    For stationary beams the degree of polarization contains only limited information on time dependent polarization. Two approaches towards assessing a beams polarization dynamics, one based on Poincare and the other on Jones vector formalism, are described leading to the notion of polarization time. Specific examples of partially temporally coherent electromagnetic beams are discussed. (Author)

  12. Dye concentration dependence of spectral triplet in one-dimensional photonic crystal with cyanine dye J-aggregate in strong coupling regime

    Science.gov (United States)

    Suzuki, Makoto; Sakata, Tomohiro; Takenobu, Ryouya; Uemura, Shinobu; Miyagawa, Hayato; Nakanishi, Shunsuke; Tsurumachi, Noriaki

    2017-10-01

    We report on the dye concentration dependence of nonlinear transmission properties of one-dimensional photonic crystal microcavities containing cyanine dye J-aggregates. Using femtosecond nonlinear transmission spectroscopy, we observed a transition from a polariton doublet state to a spectral triplet state over the whole tested concentration range, even at room temperature. In these samples, changes in the dye concentration affected the Rabi splitting energy in the linear transmission measurements; however, we found that changes in the concentration did not greatly affect the triplet formation.

  13. Polarization developments

    International Nuclear Information System (INIS)

    Prescott, C.Y.

    1993-07-01

    Recent developments in laser-driven photoemission sources of polarized electrons have made prospects for highly polarized electron beams in a future linear collider very promising. This talk discusses the experiences with the SLC polarized electron source, the recent progress with research into gallium arsenide and strained gallium arsenide as a photocathode material, and the suitability of these cathode materials for a future linear collider based on the parameters of the several linear collider designs that exist

  14. Role of quantum-confined stark effect on bias dependent photoluminescence of N-polar GaN/InGaN multi-quantum disk amber light emitting diodes

    Science.gov (United States)

    Tangi, Malleswararao; Mishra, Pawan; Janjua, Bilal; Prabaswara, Aditya; Zhao, Chao; Priante, Davide; Min, Jung-Wook; Ng, Tien Khee; Ooi, Boon S.

    2018-03-01

    We study the impact of quantum-confined stark effect (QCSE) on bias dependent micro-photoluminescence emission of the quantum disk (Q-disk) based nanowires light emitting diodes (NWs-LED) exhibiting the amber colored emission. The NWs are found to be nitrogen polar (N-polar) verified using KOH wet chemical etching and valence band spectrum analysis of high-resolution X-ray photoelectron spectroscopy. The crystal structure and quality of the NWs were investigated by high-angle annular dark field - scanning transmission electron microscopy. The LEDs were fabricated to acquire the bias dependent micro-photoluminescence spectra. We observe a redshift and a blueshift of the μPL peak in the forward and reverse bias conditions, respectively, with reference to zero bias, which is in contrast to the metal-polar InGaN well-based LEDs in the literature. Such opposite shifts of μPL peak emission observed for N-polar NWs-LEDs, in our study, are due to the change in the direction of the internal piezoelectric field. The quenching of PL intensity, under the reverse bias conditions, is ascribed to the reduction of electron-hole overlap. Furthermore, the blueshift of μPL emission with increasing excitation power reveals the suppression of QCSE resulting from the photo-generated carriers. Thereby, our study confirms the presence of QCSE for NWs-LEDs from both bias and power dependent μPL measurements. Thus, this study serves to understand the QCSE in N-polar InGaN Q-disk NWs-LEDs and other related wide-bandgap nitride nanowires, in general.

  15. Role of quantum-confined stark effect on bias dependent photoluminescence of N-polar GaN/InGaN multi-quantum disk amber light emitting diodes

    KAUST Repository

    Tangi, Malleswararao

    2018-03-09

    We study the impact of quantum-confined stark effect (QCSE) on bias dependent micro-photoluminescence emission of the quantum disk (Q-disk) based nanowires light emitting diodes (NWs-LED) exhibiting the amber colored emission. The NWs are found to be nitrogen polar (N-polar) verified using KOH wet chemical etching and valence band spectrum analysis of high-resolution X-ray photoelectron spectroscopy. The crystal structure and quality of the NWs were investigated by high-angle annular dark field - scanning transmission electron microscopy. The LEDs were fabricated to acquire the bias dependent micro-photoluminescence spectra. We observe a redshift and a blueshift of the μPL peak in the forward and reverse bias conditions, respectively, with reference to zero bias, which is in contrast to the metal-polar InGaN well-based LEDs in the literature. Such opposite shifts of μPL peak emission observed for N-polar NWs-LEDs, in our study, are due to the change in the direction of the internal piezoelectric field. The quenching of PL intensity, under the reverse bias conditions, is ascribed to the reduction of electron-hole overlap. Furthermore, the blueshift of μPL emission with increasing excitation power reveals the suppression of QCSE resulting from the photo-generated carriers. Thereby, our study confirms the presence of QCSE for NWs-LEDs from both bias and power dependent μPL measurements. Thus, this study serves to understand the QCSE in N-polar InGaN Q-disk NWs-LEDs and other related wide-bandgap nitride nanowires, in general.

  16. Strong dependence of a pioneer shrub on seed dispersal services provided by an endemic endangered lizard in a Mediterranean island ecosystem.

    Science.gov (United States)

    Neghme, Constanza; Santamaría, Luís; Calviño-Cancela, María

    2017-01-01

    The accelerating rate of vertebrate extinctions and population declines threatens to disrupt important ecological interactions, altering key ecosystem processes such as animal seed dispersal. The study of highly specialized mutualistic interactions is crucial to predict the consequences of population declines and extinctions. Islands offer unique opportunities to study highly specialized interactions, as they often have naturally depauperated faunas and are experiencing high rates of human-driven extinctions. In this study, we assess the effect of seed dispersal on seedling recruitment of Ephedra fragilis (Ephedraceae) on a Mediterranean island ecosystem. We used field data and stochastic simulation modeling to estimate seed fate and recruitment patterns of this pioneer shrub typical of arid and semiarid areas, and to estimate the dependence of recruitment on the lizard Podarcis lilfordi (Lacertidae), its only known seed disperser. Ephedra fragilis recruitment highly depended on lizards: lizards produced 3.8 times more newly-emerged seedlings than non-dispersed seeds and no seedlings from undispersed seeds survived the study period. Seed dispersal by lizards was mostly to open sites, which was key for the increased success observed, while undispersed seeds, falling under mother plants, suffered higher predation and lower seedling emergence and survival. The ability of this pioneer shrub to get established in open ground is crucial for vegetation colonization and restoration, especially on degraded lands affected by desertification, where they act as nurse plants for other species. Lizards are key in this process, which has important consequences for community structure and ecosystem functioning.

  17. Unitary Dynamics of Strongly Interacting Bose Gases with the Time-Dependent Variational Monte Carlo Method in Continuous Space

    Directory of Open Access Journals (Sweden)

    Giuseppe Carleo

    2017-08-01

    Full Text Available We introduce the time-dependent variational Monte Carlo method for continuous-space Bose gases. Our approach is based on the systematic expansion of the many-body wave function in terms of multibody correlations and is essentially exact up to adaptive truncation. The method is benchmarked by comparison to an exact Bethe ansatz or existing numerical results for the integrable Lieb-Liniger model. We first show that the many-body wave function achieves high precision for ground-state properties, including energy and first-order as well as second-order correlation functions. Then, we study the out-of-equilibrium, unitary dynamics induced by a quantum quench in the interaction strength. Our time-dependent variational Monte Carlo results are benchmarked by comparison to exact Bethe ansatz results available for a small number of particles, and are also compared to quench action results available for noninteracting initial states. Moreover, our approach allows us to study large particle numbers and general quench protocols, previously inaccessible beyond the mean-field level. Our results suggest that it is possible to find correlated initial states for which the long-term dynamics of local density fluctuations is close to the predictions of a simple Boltzmann ensemble.

  18. Nanocrystal Size-Dependent Efficiency of Quantum Dot Sensitized Solar Cells in the Strongly Coupled CdSe Nanocrystals/TiO2 System.

    Science.gov (United States)

    Yun, Hyeong Jin; Paik, Taejong; Diroll, Benjamin; Edley, Michael E; Baxter, Jason B; Murray, Christopher B

    2016-06-15

    Light absorption and electron injection are important criteria determining solar energy conversion efficiency. In this research, monodisperse CdSe quantum dots (QDs) are synthesized with five different diameters, and the size-dependent solar energy conversion efficiency of CdSe quantum dot sensitized solar cell (QDSSCs) is investigated by employing the atomic inorganic ligand, S(2-). Absorbance measurements and transmission electron microscopy show that the diameters of the uniform CdSe QDs are 2.5, 3.2, 4.2, 6.4, and 7.8 nm. Larger CdSe QDs generate a larger amount of charge under the irradiation of long wavelength photons, as verified by the absorbance results and the measurements of the external quantum efficiencies. However, the smaller QDs exhibit faster electron injection kinetics from CdSe QDs to TiO2 because of the high energy level of CBCdSe, as verified by time-resolved photoluminescence and internal quantum efficiency results. Importantly, the S(2-) ligand significantly enhances the electronic coupling between the CdSe QDs and TiO2, yielding an enhancement of the charge transfer rate at the interfacial region. As a result, the S(2-) ligand helps improve the new size-dependent solar energy conversion efficiency, showing best performance with 4.2-nm CdSe QDs, whereas conventional ligand, mercaptopropionic acid, does not show any differences in efficiency according to the size of the CdSe QDs. The findings reported herein suggest that the atomic inorganic ligand reinforces the influence of quantum confinement on the solar energy conversion efficiency of QDSSCs.

  19. High night temperature strongly impacts TCA cycle, amino acid and polyamine biosynthetic pathways in rice in a sensitivity-dependent manner.

    Science.gov (United States)

    Glaubitz, Ulrike; Erban, Alexander; Kopka, Joachim; Hincha, Dirk K; Zuther, Ellen

    2015-10-01

    Global climate change combined with asymmetric warming can have detrimental effects on the yield of crop plants such as rice (Oryza sativa L.). Little is known about metabolic responses of rice to high night temperature (HNT) conditions. Twelve cultivars with different HNT sensitivity were used to investigate metabolic changes in the vegetative stage under HNT compared to control conditions. Central metabolism, especially TCA cycle and amino acid biosynthesis, were strongly affected particularly in sensitive cultivars. Levels of several metabolites were correlated with HNT sensitivity. Furthermore, pool sizes of some metabolites negatively correlated with HNT sensitivity under control conditions, indicating metabolic pre-adaptation in tolerant cultivars. The polyamines putrescine, spermidine and spermine showed increased abundance in sensitive cultivars under HNT conditions. Correlations between the content of polyamines and 75 other metabolites indicated metabolic shifts from correlations with sugar-phosphates and 1-kestose under control to correlations with sugars and amino and organic acids under HNT conditions. Increased expression levels of ADC2 and ODC1, genes encoding enzymes catalysing the first committed steps of putrescine biosynthesis, were restricted to sensitive cultivars under HNT. Additionally, transcript levels of eight polyamine biosynthesis genes were correlated with HNT sensitivity. Responses to HNT in the vegetative stage result in distinct differences between differently responding cultivars with a dysregulation of central metabolism and an increase of polyamine biosynthesis restricted to sensitive cultivars under HNT conditions and a pre-adaptation of tolerant cultivars already under control conditions with higher levels of potentially protective compatible solutes. © The Author 2015. Published by Oxford University Press on behalf of the Society for Experimental Biology.

  20. Decrypting Strong and Weak Single-Walled Carbon Nanotubes Interactions with Mitochondrial Voltage-Dependent Anion Channels Using Molecular Docking and Perturbation Theory.

    Science.gov (United States)

    González-Durruthy, Michael; Werhli, Adriano V; Seus, Vinicius; Machado, Karina S; Pazos, Alejandro; Munteanu, Cristian R; González-Díaz, Humberto; Monserrat, José M

    2017-10-16

    The current molecular docking study provided the Free Energy of Binding (FEB) for the interaction (nanotoxicity) between VDAC mitochondrial channels of three species (VDAC1-Mus musculus, VDAC1-Homo sapiens, VDAC2-Danio rerio) with SWCNT-H, SWCNT-OH, SWCNT-COOH carbon nanotubes. The general results showed that the FEB values were statistically more negative (p  (SWCNT-VDAC1-Mus musculus) > (SWCNT-VDAC1-Homo sapiens) > (ATP-VDAC). More negative FEB values for SWCNT-COOH and OH were found in VDAC2-Danio rerio when compared with VDAC1-Mus musculus and VDAC1-Homo sapiens (p  r 2  > 0.97) was observed between n-Hamada index and VDAC nanotoxicity (or FEB) for the zigzag topologies of SWCNT-COOH and SWCNT-OH. Predictive Nanoparticles-Quantitative-Structure Binding-Relationship models (nano-QSBR) for strong and weak SWCNT-VDAC docking interactions were performed using Perturbation Theory, regression and classification models. Thus, 405 SWCNT-VDAC interactions were predicted using a nano-PT-QSBR classifications model with high accuracy, specificity, and sensitivity (73-98%) in training and validation series, and a maximum AUROC value of 0.978. In addition, the best regression model was obtained with Random Forest (R 2 of 0.833, RMSE of 0.0844), suggesting an excellent potential to predict SWCNT-VDAC channel nanotoxicity. All study data are available at https://doi.org/10.6084/m9.figshare.4802320.v2 .

  1. Two-photon spin-polarization spectroscopy in silicon-doped GaAs.

    Science.gov (United States)

    Miah, M Idrish

    2009-05-14

    We generate spin-polarized electrons in bulk GaAs using circularly polarized two-photon pumping with excess photon energy (DeltaE) and detect them by probing the spin-dependent transmission of the sample. The spin polarization of conduction band electrons is measured and is found to be strongly dependent on DeltaE. The initial polarization, pumped with DeltaE=100 meV, at liquid helium temperature is estimated to be approximately 49.5%, which is very close to the theoretical value (50%) permitted by the optical selection rules governing transitions from heavy-hole and light-hole states to conduction band states in a bulk sample. However, the polarization pumped with larger DeltaE decreases rapidly because of the exciting carriers from the split-off band.

  2. Polarization, political

    NARCIS (Netherlands)

    Wojcieszak, M.; Mazzoleni, G.; Barnhurst, K.G.; Ikeda, K.; Maia, R.C.M.; Wessler, H.

    2015-01-01

    Polarization has been studied in three different forms: on a social, group, and individual level. This entry first focuses on the undisputed phenomenon of elite polarization (i.e., increasing adherence of policy positions among the elites) and also outlines different approaches to assessing mass

  3. Unoccupied density of states of La2–xSrxNiO4+δ studied by polarization-dependent x-ray-absorption spectroscopy and bremsstrahlung isochromat spectroscopy

    NARCIS (Netherlands)

    Kuiper, P.; Elp, J. van; Sawatzky, G.A.; Fujimori, A.; Hosoya, S.; Leeuw, D.M. de

    1991-01-01

    Oxygen 1s x-ray-absorption measurements of La2–xSrxNiO4+δ (0≤x≤1.15) are presented, together with O 1s polarization-dependent x-ray absorption on single-crystal La1.85Sr0.15NiO4. It is concluded that the charge-compensating holes have mainly oxygen 2p character. The Ni 3d9 final states reached

  4. Light- and pH-dependent conformational changes in protein structure induce strong bending of purple membranes--active membranes studied by cryo-SEM.

    Science.gov (United States)

    Rhinow, Daniel; Hampp, Norbert A

    2008-10-16

    Bacteriorhodopsin (BR) undergoes a conformational change during the photocycle and the proton transport through the membrane. For the first time, we could demonstrate by direct imaging of freely suspended native purple membranes (PMs) that the flat disk-like shape of PMs changes dramatically as soon as most of the BRs are in a state characterized by a deprotonated Schiff base. Light-induced shape changes are easily observed with mutated BRs of the BR-D96N type, i.e., all variants which show an increased M 2 lifetime. On the other hand, large-scale shape changes are induced by pH changes with PM containing mutated BRs of the BR-D85T type, where Asp85 is replaced for a neutral amino acid. In such PMs, all BRs are titrated simultaneously and the resulting shape of the membranes depends on the initial shape only. As the majority of PMs in the "flat" state are more or less round disks, the bent membranes often comprise bowl-like and tube-like bent structures. The method presented here enables one to derive size changes of membrane-embedded BRs on the single molecule level from "macroscopic", easily accessible data like the curvature radii observed in cryo-SEM. The potential of BR as a pH-controlled and/or light-controlled microscaled biological actuator needs further consideration.

  5. Polarization holography

    DEFF Research Database (Denmark)

    Nikolova, L.; Ramanujam, P.S.

    Current research into holography is concerned with applications in optically storing, retrieving, and processing information. Polarization holography has many unique properties compared to conventional holography. It gives results in high efficiency, achromaticity, and special polarization...... properties. This books reviews the research carried out in this field over the last 15 years. The authors provide basic concepts in polarization and the propagation of light through anisotropic materials, before presenting a sound theoretical basis for polarization holography. The fabrication...... and characterization of azobenzene based materials, which remain the most efficient for the purpose, is described in detail. This is followed by a description of other materials that are used in polarization holography. An in-depth description of various applications, including display holography and optical storage...

  6. Dynamic nuclear spin polarization

    Energy Technology Data Exchange (ETDEWEB)

    Stuhrmann, H.B. [GKSS-Forschungszentrum Geesthacht GmbH (Germany)

    1996-11-01

    Polarized neutron scattering from dynamic polarized targets has been applied to various hydrogenous materials at different laboratories. In situ structures of macromolecular components have been determined by nuclear spin contrast variation with an unprecedented precision. The experiments of selective nuclear spin depolarisation not only opened a new dimension to structural studies but also revealed phenomena related to propagation of nuclear spin polarization and the interplay of nuclear polarisation with the electronic spin system. The observation of electron spin label dependent nuclear spin polarisation domains by NMR and polarized neutron scattering opens a way to generalize the method of nuclear spin contrast variation and most importantly it avoids precontrasting by specific deuteration. It also likely might tell us more about the mechanism of dynamic nuclear spin polarisation. (author) 4 figs., refs.

  7. HER2 signaling pathway activation and response of breast cancer cells to HER2-targeting agents is dependent strongly on the 3D microenvironment

    Energy Technology Data Exchange (ETDEWEB)

    Weigelt, Britta; Lo, Alvin T; Park, Catherine C; Gray, Joe W; Bissell, Mina J

    2009-07-27

    Development of effective and durable breast cancer treatment strategies requires a mechanistic understanding of the influence of the microenvironment on response. Previous work has shown that cellular signaling pathways and cell morphology are dramatically influenced by three-dimensional (3D) cultures as opposed to traditional two-dimensional (2D) monolayers. Here, we compared 2D and 3D culture models to determine the impact of 3D architecture and extracellular matrix (ECM) on HER2 signaling and on the response of HER2-amplified breast cancer cell lines to the HER2-targeting agents Trastuzumab, Pertuzumab and Lapatinib. We show that the response of the HER2-amplified AU565, SKBR3 and HCC1569 cells to these anti-HER2 agents was highly dependent on whether the cells were cultured in 2D monolayer or 3D laminin-rich ECM gels. Inhibition of {beta}1 integrin, a major cell-ECM receptor subunit, significantly increased the sensitivity of the HER2-amplified breast cancer cell lines to the humanized monoclonal antibodies Trastuzumab and Pertuzumab when grown in a 3D environment. Finally, in the absence of inhibitors, 3D cultures had substantial impact on HER2 downstream signaling and induced a switch between PI3K-AKT- and RAS-MAPKpathway activation in all cell lines studied, including cells lacking HER2 amplification and overexpression. Our data provide direct evidence that breast cancer cells are able to rapidly adapt to different environments and signaling cues by activating alternative pathways that regulate proliferation and cell survival, events that may play a significant role in the acquisition of resistance to targeted therapies.

  8. HER2 signaling pathway activation and response of breast cancer cells to HER2-targeting agents is dependent strongly on the 3D microenvironment.

    Science.gov (United States)

    Weigelt, Britta; Lo, Alvin T; Park, Catherine C; Gray, Joe W; Bissell, Mina J

    2010-07-01

    Development of effective and durable breast cancer treatment strategies requires a mechanistic understanding of the influence of the microenvironment on response. Previous work has shown that cellular signaling pathways and cell morphology are dramatically influenced by three-dimensional (3D) cultures as opposed to traditional two-dimensional (2D) monolayers. Here, we compared 2D and 3D culture models to determine the impact of 3D architecture and extracellular matrix (ECM) on HER2 signaling and on the response of HER2-amplified breast cancer cell lines to the HER2-targeting agents Trastuzumab, Pertuzumab and Lapatinib. We show that the response of the HER2-amplified AU565, SKBR3 and HCC1569 cells to these anti-HER2 agents was highly dependent on whether the cells were cultured in 2D monolayer or 3D laminin-rich ECM gels. Inhibition of beta1 integrin, a major cell-ECM receptor subunit, significantly increased the sensitivity of the HER2-amplified breast cancer cell lines to the humanized monoclonal antibodies Trastuzumab and Pertuzumab when grown in a 3D environment. Finally, in the absence of inhibitors, 3D cultures had substantial impact on HER2 downstream signaling and induced a switch between PI3K-AKT- and RAS-MAPK-pathway activation in all cell lines studied, including cells lacking HER2 amplification and overexpression. Our data provide direct evidence that breast cancer cells are able to rapidly adapt to different environments and signaling cues by activating alternative pathways that regulate proliferation and cell survival, events that may play a significant role in the acquisition of resistance to targeted therapies.

  9. Angular-momentum-assisted dissociation of CO in strong optical fields

    Science.gov (United States)

    Mullin, Amy; Ogden, Hannah; Murray, Matthew; Liu, Qingnan; Toro, Carlos

    2017-04-01

    Filaments are produced in CO gas by intense, chirped laser pulses. Visible emission from C2 is observed as a result of chemical reactions of highly excited CO. At laser intensities greater than 1014 W cm-2, the C2 emission shows a strong dependence on laser polarization. Oppositely chirped pulses of light with ω0 = 800 nm are recombined spatially and temporally to generate angularly accelerating electric fields (up to 30 THz) that either have an instantaneous linear polarization or act as a dynamic polarization grating that oscillates among linear and circular polarizations. The angularly accelerating linear polarization corresponds to an optical centrifuge that concurrently drives molecules into high rotational states (with J 50) and induces strong-field dissociation. Higher order excitation is observed for the time-varying laser polarization configuration that does not induce rotational excitation. The results indicate that the presence of rotational angular momentum lowers the threshold for CO dissociation in strong optical fields by coupling nuclear and electronic degrees of freedom. Support from NSF CHE-1058721 and the University of Maryland.

  10. Overexpression of KIR inhibitory ligands (HLA-I) determines that immunosurveillance of myeloma depends on diverse and strong NK cell licensing.

    Science.gov (United States)

    Martínez-Sánchez, María V; Periago, Adela; Legaz, Isabel; Gimeno, Lourdes; Mrowiec, Anna; Montes-Barqueros, Natividad R; Campillo, José A; Bolarin, José M; Bernardo, María V; López-Álvarez, María R; González, Consuelo; García-Garay, María C; Muro, Manuel; Cabañas-Perianes, Valentin; Fuster, Jose L; García-Alonso, Ana M; Moraleda, José M; Álvarez-Lopez, María R; Minguela, Alfredo

    2016-04-01

    -missing-self cancers, e.g., myeloma, mainly depends on NKc licensing.

  11. Strain dependence on polarization properties of AlGaN and AlGaN-based ultraviolet lasers grown on AlN substrates

    Energy Technology Data Exchange (ETDEWEB)

    Bryan, Zachary, E-mail: zabryan@ncsu.edu; Bryan, Isaac; Sitar, Zlatko; Collazo, Ramón [Department of Materials Science and Engineering, North Carolina State University, Raleigh, North Carolina 27695 (United States); Mita, Seiji [HexaTech, Inc., 991 Aviation Pkwy., Suite 800, Morrisville, North Carolina 27560 (United States); Tweedie, James [Adroit Materials, 2054 Kildaire Farm Rd., Suite 205, Cary, North Carolina 27518 (United States)

    2015-06-08

    Since the band ordering in AlGaN has a profound effect on the performance of UVC light emitting diodes (LEDs) and even determines the feasibility of surface emitting lasers, the polarization properties of emitted light from c-oriented AlGaN and AlGaN-based laser structures were studied over the whole composition range, as well as various strain states, quantum confinements, and carrier densities. A quantitative relationship between the theoretical valence band separation, determined using k•p theory, and the experimentally measured degree of polarization is presented. Next to composition, strain was found to have the largest influence on the degree of polarization while all other factors were practically insignificant. The lowest crossover point from the transverse electric to transverse magnetic polarized emission of 245 nm was found for structures pseudomorphically grown on AlN substrates. This finding has significant implications toward the efficiency and feasibility of surface emitting devices below this wavelength.

  12. Polar Bears

    Science.gov (United States)

    Amstrup, Steven C.; Douglas, David C.; Reynolds, Patricia E.; Rhode, E.B.

    2002-01-01

    Polar bears (Ursus maritimus) are hunted throughout most of their range. In addition to hunting polar bears of the Beaufort Sea region are exposed to mineral and petroleum extraction and related human activities such as shipping road-building, and seismic testing (Stirling 1990).Little was known at the start of this project about how polar bears move about in their environment, and although it was understood that many bears travel across political borders, the boundaries of populations had not been delineated (Amstrup 1986, Amstrup et al. 1986, Amstrup and DeMaster 1988, Garner et al. 1994, Amstrup 1995, Amstrup et al. 1995, Amstrup 2000).As human populations increase and demands for polar bears and other arctic resources escalate, managers must know the sizes and distributions of the polar bear populations. Resource managers also need reliable estimates of breeding rates, reproductive intervals, litter sizes, and survival of young and adults.Our objectives for this research were 1) to determine the seasonal and annual movements of polar bears in the Beaufort Sea, 2) to define the boundaries of the population(s) using this region, 3) to determine the size and status of the Beaufort Sea polar bear population, and 4) to establish reproduction and survival rates (Amstrup 2000).

  13. Variety of Polarized Line Profiles in Interacting Supernovae

    Science.gov (United States)

    Hoffman, Jennifer L.; Huk, L. N.; Peters, C. L.

    2013-01-01

    The dense circumstellar material that creates strong emission lines in the spectra of interacting supernovae also gives rise to complex line polarization behavior. Viewed in polarized light, the emission line profiles of these supernovae encode information about the geometrical and optical characteristics of their surrounding circumstellar material (CSM) that is inaccessible by other observational techniques. To facilitate quantitative interpretation of these spectropolarimetric signatures, we have created a large grid of model polarized line profiles using a three-dimensional radiative transfer code that simulates polarization via electron and resonant/fluorescent line scattering. The simulated polarized lines take on an array of profile shapes that vary with viewing angle and CSM properties. We present the major results from the grid and investigate the dependence of polarized line profiles on CSM characteristics including temperature, optical depth, and geometry. These results will allow more straightforward interpretation of polarized line profiles in interacting supernovae than has previously been possible. This research is supported by the National Science Foundation through the AAG program and the XSEDE collaboration, and uses the resources of the Texas Advanced Computing Center.

  14. Photocyclization reaction of a diarylmaleimide derivative in polar solvents.

    Science.gov (United States)

    Ohsumi, Masato; Hazama, Masaki; Fukaminato, Tuyoshi; Irie, Masahiro

    2008-07-28

    Photochromism of a symmetric diarylmaleimide derivative, having two thiophene rings (1), and a non-symmetric derivative having a S,S-dioxide thiophene ring and a thiophene ring (2) as the aryl moieties, was studied in various solvents. The photocyclization quantum yield of gradually decreased with increasing the solvent polarity and the reaction was not observed in polar solvents, such as ethanol and acetonitrile; on the other hand, such a strong solvent dependence of the photocyclization reaction was not observed for ; the different behavior is attributed to the weaker electron donating ability of the S,S-dioxide thiophene ring.

  15. Polarization properties of below-threshold harmonics from aligned molecules H2+ in linearly polarized laser fields.

    Science.gov (United States)

    Dong, Fulong; Tian, Yiqun; Yu, Shujuan; Wang, Shang; Yang, Shiping; Chen, Yanjun

    2015-07-13

    We investigate the polarization properties of below-threshold harmonics from aligned molecules in linearly polarized laser fields numerically and analytically. We focus on lower-order harmonics (LOHs). Our simulations show that the ellipticity of below-threshold LOHs depends strongly on the orientation angle and differs significantly for different harmonic orders. Our analysis reveals that this LOH ellipticity is closely associated with resonance effects and the axis symmetry of the molecule. These results shed light on the complex generation mechanism of below-threshold harmonics from aligned molecules.

  16. Optimization of s-Polarization Sensitivity in Apertureless Near-Field Optical Microscopy

    Directory of Open Access Journals (Sweden)

    Yuika Saito

    2012-01-01

    Full Text Available It is a general belief in apertureless near-field microscopy that the so-called p-polarization configuration, where the incident light is polarized parallel to the axis of the probe, is advantageous to its counterpart, the s-polarization configuration, where the incident light is polarized perpendicular to the probe axis. While this is true for most samples under common near-field experimental conditions, there are samples which respond better to the s-polarization configuration due to their orientations. Indeed, there have been several reports that have discussed such samples. This leads us to an important requirement that the near-field experimental setup should be equipped with proper sensitivity for measurements with s-polarization configuration. This requires not only creation of effective s-polarized illumination at the near-field probe, but also proper enhancement of s-polarized light by the probe. In this paper, we have examined the s-polarization enhancement sensitivity of near-field probes by measuring and evaluating the near-field Rayleigh scattering images constructed by a variety of probes. We found that the s-polarization enhancement sensitivity strongly depends on the sharpness of the apex of near-field probes. We have discussed the efficient value of probe sharpness by considering a balance between the enhancement and the spatial resolution, both of which are essential requirements of apertureless near-field microscopy.

  17. Polarization of Bremsstrahlung

    International Nuclear Information System (INIS)

    Miller, J.

    1957-01-01

    The numerical results for the polarization of Bremsstrahlung are presented. The multiple scattering of electrons in the target is taken into account. The angular-and photon energy dependences are seen on the curves for an incident 25 MeV electron energy. (Author) [fr

  18. Polarization-dependent X-ray-absorption spectroscopy of $RNi_{2} B_{2}$ C (R=Er $\\to$ Lu) Reduced Ni-3d occupancy in $YbNi_{2} B_{2} C$

    CERN Document Server

    Mazumdar, C; Von Lips, H; Golden, M S; Fink, J; Canfield, P C; Kaindl, G

    2001-01-01

    We present here the results of polarization-dependent X-ray- absorption near-edge structure (XANES) studies at the B-K, C-K, and Ni-L/sub 3/ thresholds of single-crystalline borocarbide compounds RNi/sub 2/B/sub 2/C (with R=Er to Lu) using bulk-sensitive fluorescence yield technique. The Ni-L/sub 3/ XANES spectrum for YbNi /sub 2/B/sub 2/C with photon polarization parallel to the ab plane is significantly more intense than in analogous spectra of other members of this series. This indicates a reduced Ni-3d occupancy in the Ni /sub 2/B/sub 2/ layer in YbNi/sub 2/B/sub 2/C, a fact that might be responsible for the absence of superconductivity in this material. (26 refs).

  19. Spin-polarization reversal at the interface between benzene and Fe(100)

    KAUST Repository

    Goumri-Said, Souraya

    2013-01-03

    The spin-polarization at the interface between Fe(100) and a benzene is investigated theoretically using density functional theory for two positions of the organic molecule: planar and perpendicular with respect to the substrate. The electronic and magnetic properties as well as the spin-polarization close to the Fermi level strongly depend on the benzene position on the iron surface. An inversion of the spin-polarization is induced by p-d hybridization and charge transfer from the iron to the carbon sites in both configurations.

  20. Valley polarization in magnetically doped single-layer transition-metal dichalcogenides

    KAUST Repository

    Cheng, Yingchun

    2014-04-28

    We demonstrate that valley polarization can be induced and controlled in semiconducting single-layer transition-metal dichalcogenides by magnetic doping, which is important for spintronics, valleytronics, and photonics devices. As an example, we investigate Mn-doped MoS2 by first-principles calculations. We study how the valley polarization depends on the strength of the spin orbit coupling and the exchange interaction and discuss how it can be controlled by magnetic doping. Valley polarization by magnetic doping is also expected for other honeycomb materials with strong spin orbit coupling and the absence of inversion symmetry.

  1. Effect of polarization force on the Jeans instability in collisional dusty plasmas

    Science.gov (United States)

    A, ABBASI; M, R. RASHIDIAN VAZIRI

    2018-03-01

    The Jeans instability in collisional dusty plasmas has been analytically investigated by considering the polarization force effect. Instabilities due to dust-neutral and ion-neutral drags can occur in electrostatic waves of collisional dusty plasmas with self-gravitating particles. In this study, the effect of gravitational force on heavy dust particles is considered in tandem with both the polarization and electrostatic forces. The theoretical framework has been developed and the dispersion relation and instability growth rate have been derived, assuming the plane wave approximation. The derived instability growth rate shows that, in collisional dusty plasmas, the Jeans instability strongly depends on the magnitude of the polarization force.

  2. Polarized electrogowdy spacetimes censored

    Energy Technology Data Exchange (ETDEWEB)

    Nungesser, Ernesto, E-mail: ernesto.nungesser@aei.mpg.d [Max-Planck-Institut fuer Gravitationsphysik, Albert-Einstein-Institut, Am Muehlenberg 1, 14476 Potsdam (Germany)

    2010-05-01

    A sketch of the proof of strong cosmic censorship is presented for a class of solutions of the Einstein-Maxwell equations, those with polarized Gowdy symmetry. A key element of the argument is the observation that by means of a suitable choice of variables the central equations in this problem can be written in a form where they are identical to the central equations for general (i.e. non-polarized) vacuum Gowdy spacetimes. Using this it is seen that the results of Ringstroem on strong cosmic censorship in the vacuum case have implications for the Einstein-Maxwell case. Working out the geometrical meaning of these analytical results leads to the main conclusion.

  3. Using ZnO-Cr2O3-ZnO heterostructures to characterize polarization penetration depth through non-polar films.

    Science.gov (United States)

    Zhu, Xiaodong; Jhang, Jin-Hao; Zhou, Chao; Dagdeviren, Omur E; Chen, Zheng; Schwarz, Udo D; Altman, Eric I

    2017-12-13

    The ability to affect the surface properties of non-polar Cr 2 O 3 films through polar ZnO(0001) and (0001[combining macron]) supports was investigated by characterizing the polarity of ZnO films grown on top of the Cr 2 O 3 surfaces. The growth and geometric and electronic structures of the ZnO films were characterized with X-ray photoelectron spectroscopy, ultra-violet photoelectron spectroscopy, reflection high-energy electron diffraction, low-energy electron diffraction, and X-ray diffraction. The ZnO growth mode was Stranski-Krastanov, which can be attributed to the ZnO layers initially adopting a non-polar structure with a lower surface tension before transitioning to the polar bulk structure with a higher surface energy. A similar result has been reported for ZnO growth on α-Al 2 O 3 (0001), which is isostructural with Cr 2 O 3 . The polarity of the added ZnO layer was determined by examining the surface morphology following wet chemical etching with atomic force microscopy and by characterizing the surface reactivity via temperature-programmed desorption of alcohols, which strongly depends on the ZnO polarization direction. Consistent with prior work on ZnO growth on bulk Cr 2 O 3 (0001), both measurements indicate that thick Cr 2 O 3 layers support ZnO(0001[combining macron]) growth regardless of the underlying ZnO substrate polarization; however, the polarization direction of ZnO films grown on Cr 2 O 3 films less than three repeat units thick follows the direction of the underlying substrate polarization. These findings show that it is possible to manipulate the surface properties of non-polar materials with a polar substrate, but that the effect does not penetrate past just a couple of repeat units.

  4. On the nature of IMF polarity dependent asymmetries in solar wind plasma properties during the minimum of sunspot cycles 23 and 24

    Science.gov (United States)

    Pereira, B. Felix; Philip, Bijoy John; Girish, T. E.

    2016-03-01

    The monthly solar wind speed and density observed near 1 AU in IMF sectors of opposite magnetic polarity are studied during the minimum of sunspot cycles 23 and 24. During sunspot minima, the IMF is pointing away from the sun (Away sector) in the north of the Heliospheric Current Sheet (HCS) and pointing towards the sun (Toward sector) in the south of HCS during odd sunspot cycles and the same process is reversed during the even cycles. During this period, the solar wind plasma parameters (number density and speed) show a systematic month to month variation with solar wind number density decreases and velocity increases from equator to poles (heliomagnetic latitudinal organization) only in 'Away' IMF sectors compared to 'Toward' IMF sectors. This feature is particularly more evident for low speed solar wind and happens in a helio-hemisphere with a larger polar coronal hole. The association of the above phenomena with north-south asymmetry in coronal and solar wind flow characteristics will be discussed.

  5. Monitoring the distributed impact wave on a concrete slab due to the traffic based on polarization dependence on stimulated Brillouin scattering

    International Nuclear Information System (INIS)

    Bao Xiaoyi; Zhang Chunshu; Li Wenhai; Eisa, M; El-Gamal, S; Benmokrane, B

    2008-01-01

    For the first time to our knowledge, distributed impact waves due to the highway traffic on concrete slabs reinforced with FRP bars are monitored in real time using stimulated Brillouin scattering. The impact wave is caused by the traffic passing on the highway pavement at high speed (>100 km h −1 ), which induced pressure on the concrete slabs, and in turn created a local birefringence change, leading to variation of the local state of polarization change (SOP). The pump and probe waves of the stimulated Brillouin scattering 'see' the SOP change and react with a decrease of the Brillouin gain or loss signal, when the pump and probe waves have the same input polarization state. The frequency difference between the pump and probe waves are locked at the static-strain-related Brillouin frequency. Optical fiber was embedded throughout the concrete pavement continuously reinforced with FRP bars in Highway 40 East, Montréal, Quebec to detect impact waves caused by cars and trucks passing on these pavements at a sampling rate of 10 kHz. A spatial resolution of 2 m was used over a sensing length of 300 m

  6. Quantitative cell polarity imaging defines leader-to-follower transitions during collective migration and the key role of microtubule-dependent adherens junction formation.

    Science.gov (United States)

    Revenu, Céline; Streichan, Sebastian; Donà, Erika; Lecaudey, Virginie; Hufnagel, Lars; Gilmour, Darren

    2014-03-01

    The directed migration of cell collectives drives the formation of complex organ systems. A characteristic feature of many migrating collectives is a 'tissue-scale' polarity, whereby 'leader' cells at the edge of the tissue guide trailing 'followers' that become assembled into polarised epithelial tissues en route. Here, we combine quantitative imaging and perturbation approaches to investigate epithelial cell state transitions during collective migration and organogenesis, using the zebrafish lateral line primordium as an in vivo model. A readout of three-dimensional cell polarity, based on centrosomal-nucleus axes, allows the transition from migrating leaders to assembled followers to be quantitatively resolved for the first time in vivo. Using live reporters and a novel fluorescent protein timer approach, we investigate changes in cell-cell adhesion underlying this transition by monitoring cadherin receptor localisation and stability. This reveals that while cadherin 2 is expressed across the entire tissue, functional apical junctions are first assembled in the transition zone and become progressively more stable across the leader-follower axis of the tissue. Perturbation experiments demonstrate that the formation of these apical adherens junctions requires dynamic microtubules. However, once stabilised, adherens junction maintenance is microtubule independent. Combined, these data identify a mechanism for regulating leader-to-follower transitions within migrating collectives, based on the relocation and stabilisation of cadherins, and reveal a key role for dynamic microtubules in this process.

  7. The Bochum Polarized Target

    International Nuclear Information System (INIS)

    Reicherz, G.; Goertz, S.; Harmsen, J.; Heckmann, J.; Meier, A.; Meyer, W.; Radtke, E.

    2001-01-01

    The Bochum 'Polarized Target' group develops the target material 6 LiD for the COMPASS experiment at CERN. Several different materials like alcohols, alcanes and ammonia are under investigation. Solid State Targets are polarized in magnetic fields higher than B=2.5T and at temperatures below T=1K. For the Dynamic Nuclear Polarization process, paramagnetic centers are induced chemically or by irradiation with ionizing beams. The radical density is a critical factor for optimization of polarization and relaxation times at adequate magnetic fields and temperatures. In a high sensitive EPR--apparatus, an evaporator and a dilution cryostat with a continuous wave NMR--system, the materials are investigated and optimized. To improve the polarization measurement, the Liverpool NMR-box is modified by exchanging the fixed capacitor for a varicap diode which not only makes the tuning very easy but also provides a continuously tuned circuit. The dependence of the signal area upon the circuit current is measured and it is shown that it follows a linear function

  8. Political polarization

    OpenAIRE

    Dixit, Avinash K.; Weibull, Jörgen W.

    2007-01-01

    Failures of government policies often provoke opposite reactions from citizens; some call for a reversal of the policy, whereas others favor its continuation in stronger form. We offer an explanation of such polarization, based on a natural bimodality of preferences in political and economic contexts and consistent with Bayesian rationality.

  9. Political polarization.

    Science.gov (United States)

    Dixit, Avinash K; Weibull, Jörgen W

    2007-05-01

    Failures of government policies often provoke opposite reactions from citizens; some call for a reversal of the policy, whereas others favor its continuation in stronger form. We offer an explanation of such polarization, based on a natural bimodality of preferences in political and economic contexts and consistent with Bayesian rationality.

  10. Velocity barrier-controlled of spin-valley polarized transport in monolayer WSe2 junction

    Science.gov (United States)

    Qiu, Xuejun; Lv, Qiang; Cao, Zhenzhou

    2018-05-01

    In this work, we have theoretically investigated the influence of velocity barrier on the spin-valley polarized transport in monolayer (ML) WSe2 junction with a large spin-orbit coupling (SOC). Both the spin-valley resolved transmission probabilities and conductance are strong dependent on the velocity barrier, as the velocity barrier decreases to 0.06, a spin-valley polarization of exceeding 90% is observed, which is distinct from the ML MoS2 owing to incommensurable SOC. In addition, the spin-valley polarization is further increased above 95% in a ML WSe2 superlattice, in particular, it's found many extraordinary velocity barrier-dependent transport gaps for multiple barrier due to evanescent tunneling. Our results may open an avenue for the velocity barrier-controlled high-efficiency spin and valley polarizations in ML WSe2-based electronic devices.

  11. π--induced single charge exchange on polarized 3He

    International Nuclear Information System (INIS)

    Zhao, Q.; Burleson, S.; Blanchard, T.

    1995-01-01

    Asymmetries, A y , for the (π - ,π 0 ) reaction on polarized 3 He were measured using the pion beam of the P3W channel at LAMPF. The π 0 were detected with the new Neutral Meson Spectrometer (NMS) in coincidence with recoiling tritons. The recoil detector consisted of scintillation-counter telescopes and a wire chamber that provided energy-loss and direction information, respectively. The polarized gaseous 3 He target developed at TRIUMF was modified and run with the use of two diode lasers. Polarizations were typically 50%. The A y taken at T π = 200 MeV between 60 and 105 degrees were found to be strongly angle-dependent. The results will be compared with the theoretical predictions

  12. Evolutionary divergence of plant borate exporters and critical amino acid residues for the polar localization and boron-dependent vacuolar sorting of AtBOR1

    KAUST Repository

    Wakuta, Shinji

    2015-01-24

    Boron (B) is an essential micronutrient for plants but is toxic when accumulated in excess. The plant BOR family encodes plasma membrane-localized borate exporters (BORs) that control translocation and homeostasis of B under a wide range of conditions. In this study, we examined the evolutionary divergence of BORs among terrestrial plants and showed that the lycophyte Selaginella moellendorffii and angiosperms have evolved two types of BOR (clades I and II). Clade I includes AtBOR1 and homologs previously shown to be involved in efficient transport of B under conditions of limited B availability. AtBOR1 shows polar localization in the plasma membrane and high-B-induced vacuolar sorting, important features for efficient B transport under low-B conditions, and rapid down-regulation to avoid B toxicity. Clade II includes AtBOR4 and barley Bot1 involved in B exclusion for high-B tolerance. We showed, using yeast complementation and B transport assays, that three genes in S. moellendorffii, SmBOR1 in clade I and SmBOR3 and SmBOR4 in clade II, encode functional BORs. Furthermore, amino acid sequence alignments identified an acidic di-leucine motif unique in clade I BORs. Mutational analysis of AtBOR1 revealed that the acidic di-leucine motif is required for the polarity and high-B-induced vacuolar sorting of AtBOR1. Our data clearly indicated that the common ancestor of vascular plants had already acquired two types of BOR for low- and high-B tolerance, and that the BOR family evolved to establish B tolerance in each lineage by adapting to their environments. © The Author 2015. Published by Oxford University Press on behalf of Japanese Society of Plant Physiologists.

  13. Current-induced spin polarization in a spin-polarized two-dimensional electron gas with spin-orbit coupling

    International Nuclear Information System (INIS)

    Wang, C.M.; Pang, M.Q.; Liu, S.Y.; Lei, X.L.

    2010-01-01

    The current-induced spin polarization (CISP) is investigated in a combined Rashba-Dresselhaus spin-orbit-coupled two-dimensional electron gas, subjected to a homogeneous out-of-plane magnetization. It is found that, in addition to the usual collision-related in-plane parts of CISP, there are two impurity-density-free contributions, arising from intrinsic and disorder-mediated mechanisms. The intrinsic parts of spin polarization are related to the Berry curvature, analogous with the anomalous and spin Hall effects. For short-range collision, the disorder-mediated spin polarizations completely cancel the intrinsic ones and the total in-plane components of CISP equal those for systems without magnetization. However, for remote disorders, this cancellation does not occur and the total in-plane components of CISP strongly depend on the spin-orbit interaction coefficients and magnetization for both pure Rashba and combined Rashba-Dresselhaus models.

  14. Polarization potentials for the 208Pb(7Li,6Li)209Pb transfer

    Science.gov (United States)

    Keeley, N.; Rusek, K.

    1997-12-01

    Recent optical model analyses of near-barrier 7Li+208Pb elastic scattering data found a peak in the energy dependence of WOM, the strength of the imaginary part of the optical model potential at the strong absorption radius. It was speculated that this might be due to the polarization potentials produced by couplings to the 208Pb(7Li,6Li)209Pb transfer channels. In this Brief Report we show explicitly that such couplings do indeed produce polarization potentials with the same energy dependence as that observed for the empirical optical potentials.

  15. Polarized advanced fuel reactors

    International Nuclear Information System (INIS)

    Kulsrud, R.M.

    1987-07-01

    The d- 3 He reaction has the same spin dependence as the d-t reaction. It produces no neutrons, so that if the d-d reactivity could be reduced, it would lead to a neutron-lean reactor. The current understanding of the possible suppression of the d-d reactivity by spin polarization is discussed. The question as to whether a suppression is possible is still unresolved. Other advanced fuel reactions are briefly discussed. 11 refs

  16. Hyperosmotic stress strongly potentiates serum response factor (SRF)-dependent transcriptional activity in ehrlich lettré ascites cells through a mechanism involving p38 mitogen-activated protein kinase

    DEFF Research Database (Denmark)

    Gorbatenko, Andrej; Wiwel, Maria; Klingberg, Henrik

    2011-01-01

    ) and cAMP response element-binding protein (CREB) are differentially regulated in ELA cells. SRF Ser103 phosphorylation and SRF-dependent transcriptional activity were strongly augmented 5–30¿min and 24¿h, respectively, after hyperosmotic stress (50% increase in extracellular ionic strength), in a p38...... is transiently inhibited while p38 MAPK is activated, in turn impacting on cell survival (Pedersen et al., 2007, Cell Physiol Biochem 20: 735–750). Here, we show that downstream of these kinases, two transcription factors with major roles in control of cell proliferation and death, serum response factor (SRF......Long-term osmotic stress results in altered gene transcription, however, with the exception of the TonE/TonEBP system, the underlying mechanisms are poorly understood. We previously showed that upon osmotic shrinkage of Ehrlich Lettré Ascites (ELA) fibroblasts, the MEK1-ERK1/2 pathway...

  17. Optical properties of InN nanocolumns: Electron accumulation at InN non-polar surfaces and dependence on the growth conditions

    Energy Technology Data Exchange (ETDEWEB)

    Segura-Ruiz, J.; Cantarero, A. [Materials Science Institute, University of Valencia (Spain); Garro, N. [Materials Science Institute, University of Valencia (Spain); Fundacio General de la Universitat de Valencia, Valencia (Spain); Iikawa, F. [Instituto de Fisica ' ' Gleb Wataghin' ' , UNICAMP, Campinas-SP (Brazil); Denker, C.; Malindretos, J.; Rizzi, A. [IV. Physikalisches Institut, Georg-August Universitaet Goettingen (Germany)

    2009-06-15

    InN nanocolumns grown by plasma-assisted molecular beam epitaxy have been studied by photoluminescence (PL) and photoluminescence excitation (PLE). The PL peak energy was red-shifted with respect to the PLE onset and both energies were higher than the low temperature band-gap reported for InN. PL and PLE experiments for different excitation and detection energies indicated that the PL peaks were homogeneously broadened. This overall phenomenology has been attributed to the effects of an electron accumulation layer present at the non-polar surfaces of the InN nanocolumns. Variations in the growth conditions modify the edge of the PLE spectra and the PL peak energies evidencing that the density of free electrons can be somehow controlled by the growth parameters. It was observed that In-BEP and substrate temperature leading to shorter In diffusion lengths diminished the effects of the electron accumulation layer on the optical properties. (copyright 2009 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim) (orig.)

  18. Optical properties of InN nanocolumns: Electron accumulation at InN non-polar surfaces and dependence on the growth conditions

    International Nuclear Information System (INIS)

    Segura-Ruiz, J.; Cantarero, A.; Garro, N.; Iikawa, F.; Denker, C.; Malindretos, J.; Rizzi, A.

    2009-01-01

    InN nanocolumns grown by plasma-assisted molecular beam epitaxy have been studied by photoluminescence (PL) and photoluminescence excitation (PLE). The PL peak energy was red-shifted with respect to the PLE onset and both energies were higher than the low temperature band-gap reported for InN. PL and PLE experiments for different excitation and detection energies indicated that the PL peaks were homogeneously broadened. This overall phenomenology has been attributed to the effects of an electron accumulation layer present at the non-polar surfaces of the InN nanocolumns. Variations in the growth conditions modify the edge of the PLE spectra and the PL peak energies evidencing that the density of free electrons can be somehow controlled by the growth parameters. It was observed that In-BEP and substrate temperature leading to shorter In diffusion lengths diminished the effects of the electron accumulation layer on the optical properties. (copyright 2009 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim) (orig.)

  19. Schrodinger-Poisson Modeling of AlxGa1-xN/GaN Heterostructures Employing Tailored Depth-Dependent Aluminum Concentration for Polarization Grading

    Science.gov (United States)

    Calame, Jeffrey; Chernyavskiy, Igor; Ancona, Mario; Meyer, David

    Polarization-gradient profiling of AlxGa1-xN/GaN heterostructures in the vertical (depth) direction, achieved by deliberate spatial tailoring of the aluminum concentration profile, can be used to control the spatial structure of the conducting electron gas in high electron mobility transistors. In particular, the typical two-dimensional electron gas of abrupt heterostructures can exhibit a more three-dimensional distribution in graded structures. This offers the possibility of improved device linearity through deliberate vertical heterostructure engineering, which can minimize or compensate for various scattering mechanisms that contribute to nonlinearity. Schrodinger-Poisson modeling (i.e., the Hartree approximation) is used to study the electron density profiles that result from such deliberate grading, and how those profiles evolve with the application of biasing vertical electric fields across the heterostructure. Implications of the results on device linearity will be discussed. Comparisons between the electron density profiles predicted by the Schrodinger-Poisson modeling and those obtained by density-gradient theory will be made in selected examples. Work supported by the U.S. Office of Naval Research.

  20. Polarization-Directed Surface Plasmon Polariton Launching

    Energy Technology Data Exchange (ETDEWEB)

    Gong, Yu; Joly, Alan G.; El-Khoury, Patrick Z.; Hess, Wayne P.

    2017-01-05

    The relative intensities of propagating surface plasmons (PSPs) simultaneously launched from opposing edges of a symmetric trench structure etched into a silver thin film may be controllably varied by tuning the linear polarization of the driving field. This is demonstrated through transient multiphoton photoemission electron microscopy measurements performed using a pair of spatially separated phase-locked femtosecond pulses. Our measurements are rationalized using finite-difference time domain simulations, which reveal that the coupling efficiency into the PSP modes is inversely proportional to the magnitude of the localized surface plasmon fields excited at the trench edges. Additional experiments on single step edges also show asymmetric PSP launching with respect to polarization, analogous to the trench results. Our combined experimental and computational results allude to the interplay between localized and propagating surface plasmon modes in the trench; strong coupling to the localized modes at the edges correlates to weak coupling to the PSP modes. Simultaneous excitation of the electric fields localized at both edges of the trench results in complex interactions between the right- and left-side PSP modes with Fabry-Perot and cylindrical modes. This results in a trench width-dependent PSP intensity ratio using otherwise identical driving fields. A systematic exploration of polarization directed PSP launching from a series of trench structures reveals an optimal PSP contrast ratio of 4.2 using a 500 nm-wide trench.

  1. Dependence of matrix effect on ionization polarity during LC-ESI-MS analysis of derivatized amino acids in some natural samples.

    Science.gov (United States)

    Oldekop, Maarja-Liisa; Rebane, Riin; Herodes, Koit

    2017-10-01

    Matrix effect, the influence of co-eluting components on the ionization efficiency of the analyte, affects the trueness and precision of the LC-ESI-MS analysis. Derivatization can reduce or eliminate matrix effect, for example, diethyl ethoxymethylenemalonate (DEEMM) derivatives have shown less matrix effect compared to other derivatives. Moreover, the use of negative ion mode can further reduce matrix effect. In order to investigate the combination of derivatization and different ionization modes, an LC-ESI-MS/MS method using alternating positive/negative ion mode was developed and validated. The analyses in positive and negative ion modes had comparable limit of quantitation values. The influence of ESI polarity on matrix effect was investigated during the analysis of 22 DEEMM-derivatized amino acids in herbal extracts and honeys. Sample dilution approach was used for the evaluation of the presence of matrix effect. Altogether, 4 honeys and 11 herbal extracts were analyzed, and the concentrations of 22 amino acids in the samples are presented. In the positive ion mode, matrix effect was observed for several amino acid derivatives and the matrix effect was stronger in honey samples compared to the herbal extracts. The negative ion mode was free from matrix effect, with only few exceptions in honeys (average relative standard deviation over all analytes and matrices was 8%; SD = 7%). The matrix effect was eliminated in the positive ion mode by sample dilution and agreement between concentrations from the two ion modes was achieved for most amino acids. In conclusion, it was shown that the combination of derivatization and negative ion mode can be a powerful tool for minimizing matrix effect in more complicated applications.

  2. Study of the polarization dependence of the photoelectric effect in the soft X-ray band - A focal plane photoelectric stellar X-ray polarimeter for the Spectrum-X-Gamma mission

    International Nuclear Information System (INIS)

    Heckler, A.; Blaer, A.; Kaaret, P.; Novick, R.

    1989-01-01

    An experimental study of the polarization dependence of the photoelectric effect in cesium iodide in the soft X-ray band was started (Heckler et al., 1989). At a grazing angle of 10 degrees and a photon energy of 2.6 keV, it is found that the photoelectric yield from a thin layer of evaporated cesium iodide varies by 12.4 percent as the polarization vector of the incident X-ray beam is rotated about the line-of-sight. The rotation angle corresponding to the maximum photoyield is displaced by 16 degrees from the normal to the photocathode. This modulation and phase shift are in good agreement with the results recently reported by Fraser, et al. (1989) It is shown that a focal plane stellar X-ray polarimeter based on this photoelectric effect will be substantially more efficient than convential X-ray polarimeters such as those based on either Bragg reflection or scattering from low atomic number targets. 7 refs

  3. Repulsive polarons and itinerant ferromagnetism in strongly polarized Fermi gases

    DEFF Research Database (Denmark)

    Massignan, Pietro; Bruun, Georg

    2011-01-01

    We analyze the properties of a single impurity immersed in a Fermi sea. At positive energy and scattering lengths, we show that the system possesses a well-defined but metastable excitation, the repulsive polaron, and we calculate its energy, quasiparticle residue and effective mass. From a therm...

  4. Strategic Polarization.

    Science.gov (United States)

    Kalai, Adam; Kalai, Ehud

    2001-08-01

    In joint decision making, similarly minded people may take opposite positions. Consider the example of a marriage in which one spouse gives generously to charity while the other donates nothing. Such "polarization" may misrepresent what is, in actuality, a small discrepancy in preferences. It may be that the donating spouse would like to see 10% of their combined income go to charity each year, while the apparently frugal spouse would like to see 8% donated. A simple game-theoretic analysis suggests that the spouses will end up donating 10% and 0%, respectively. By generalizing this argument to a larger class of games, we provide strategic justification for polarization in many situations such as debates, shared living accommodations, and disciplining children. In some of these examples, an arbitrarily small disagreement in preferences leads to an arbitrarily large loss in utility for all participants. Such small disagreements may also destabilize what, from game-theoretic point of view, is a very stable equilibrium. Copyright 2001 Academic Press.

  5. Ca(2+-dependent regulation of the Ca(2+ concentration in the myometrium mitochondria. II. Ca(2+ effects on mitochondria membranes polarization and [Ca(2+](m

    Directory of Open Access Journals (Sweden)

    L. G. Babich

    2017-06-01

    Full Text Available It is known that Ca2+ accumulation in the mitochondria undergoes complex regulation by Ca2+ itself. But the mechanisms of such regulation are still discussed. In this paper we have shown that Ca ions directly or indirectly regulate the level of myometrium mitochondria membranes polarization. The additions of 100 µM Ca2+ were accompanied by depolarization of the mitochondria membranes. The following experiments were designed to study the impact of Ca2+ on the myometrium mitochondria [Ca2+]m. Isolated myometrium mitochondria were preincubated without or with 10 μM Са2+ followed by 100 μM Са2+ addition. Experiments were conducted in three mediums: without ATP and Mg2+ (0-medium, in the presence of 3 mM Mg2+ (Mg-medium and 3 mM Mg2+ + 3 mM ATP (Mg,ATP-medium. It was shown that the effects of 10 μM Са2+ addition were different in different mediums, namely in 0- and Mg-medium the [Ca2+]m values increased, whereas in Mg,ATP-medium statistically reliable changes were not registered. Preincubation of mitochondria with 10 μM Са2+ did not affect the [Ca2+]m value after the addition of 100 μM Са2+. The [Ca2+]m values after 100 μM Са2+ addition were the same in 0- and Mg,ATP-mediums and somewhat lower in Mg-medium. Preliminary incubation of mitochondria with 10 μM Са2+ in 0- and Mg-mediums reduced changes of Fluo 4 normalized fluorescence values that were induced by 100 μM Са2+ additions, but in Mg,ATP-medium such differences were not recorded. It is concluded that Са2+ exchange in myometrium mitochondria is regulated by the concentration of Ca ions as in the external medium, so in the matrix of mitochondria. The medium composition had a significant impact on the [Са2+]m values in the absence of exogenous cation. It is suggested that light increase of [Са2+]m before the addition of 100 μM Са2+ may have a positive effect on the functional activity of the mitochondria.

  6. Mechanical writing of ferroelectric polarization.

    Science.gov (United States)

    Lu, H; Bark, C-W; Esque de los Ojos, D; Alcala, J; Eom, C B; Catalan, G; Gruverman, A

    2012-04-06

    Ferroelectric materials are characterized by a permanent electric dipole that can be reversed through the application of an external voltage, but a strong intrinsic coupling between polarization and deformation also causes all ferroelectrics to be piezoelectric, leading to applications in sensors and high-displacement actuators. A less explored property is flexoelectricity, the coupling between polarization and a strain gradient. We demonstrate that the stress gradient generated by the tip of an atomic force microscope can mechanically switch the polarization in the nanoscale volume of a ferroelectric film. Pure mechanical force can therefore be used as a dynamic tool for polarization control and may enable applications in which memory bits are written mechanically and read electrically.

  7. Mechanical Writing of Ferroelectric Polarization

    Science.gov (United States)

    Lu, H.; Bark, C.-W.; Esque de los Ojos, D.; Alcala, J.; Eom, C. B.; Catalan, G.; Gruverman, A.

    2012-04-01

    Ferroelectric materials are characterized by a permanent electric dipole that can be reversed through the application of an external voltage, but a strong intrinsic coupling between polarization and deformation also causes all ferroelectrics to be piezoelectric, leading to applications in sensors and high-displacement actuators. A less explored property is flexoelectricity, the coupling between polarization and a strain gradient. We demonstrate that the stress gradient generated by the tip of an atomic force microscope can mechanically switch the polarization in the nanoscale volume of a ferroelectric film. Pure mechanical force can therefore be used as a dynamic tool for polarization control and may enable applications in which memory bits are written mechanically and read electrically.

  8. DISCOVERY OF POLARIZATION REVERBERATION IN NGC 4151

    Energy Technology Data Exchange (ETDEWEB)

    Gaskell, C. Martin; Shoji, Masatoshi [Department of Physics and Astronomy, University of Nebraska, Lincoln, NE 68588-0111 (United States); Goosmann, Rene W. [Observatoire astronomique de Strasbourg, 11 rue de l' Universite, F-67000 Strasbourg (France); Merkulova, Nelly I.; Shakhovskoy, Nikolay M., E-mail: martin.gaskell@uv.cl, E-mail: mshoji@astro.as.utexas.edu, E-mail: rene.goosmann@astro.unistra.fr [Crimean Astrophysical Observatory, Nauchny, Crimea 98409 (Ukraine)

    2012-04-20

    Observations of the optical polarization of NGC 4151 in 1997-2003 show variations of an order of magnitude in the polarized flux while the polarization position angle remains constant. The amplitude of variability of the polarized flux is comparable to the amplitude of variability of the total U-band flux, except that the polarized flux follows the total flux with a lag of 8 {+-} 3 days. The time lag and the constancy of the position angle strongly favor a scattering origin for the variable polarization rather than a non-thermal synchrotron origin. The orientation of the position angle of the polarized flux (parallel to the radio axis) and the size of the lag imply that the polarization arises from electron scattering in a flattened region within the low-ionization component of the broad-line region. Polarization from dust scattering in the equatorial torus is ruled out as the source of the lag in polarized flux because it would produce a larger lag and, unless the half-opening angle of the torus is >53 Degree-Sign , the polarization would be perpendicular to the radio axis. We note a long-term change in the percentage of polarization at similar total flux levels, and this could be due either to changing non-axisymmetry in the optical continuum emission or a change in the number of scatterers on a timescale of years.

  9. Study of temperature dependent local structure by polarized Cu K-edge EXAFS measurements on La sub 2 sub - sub x Sr sub x CuO sub 4 (x=0.105, 0.13, 0.20)

    CERN Document Server

    Saini, N L; Bianconi, A; Oyanagi, H; Ito, T; Oka, K

    2003-01-01

    We have studied temperature dependent local structure of superconducting La sub 2 sub - sub x Sr sub x CuO sub 4 (0.105, 0.13, 0.20) single crystals by Cu K-edge extended x-ray absorption fine structure (EXAFS) measurements with polarization parallel to the in-plane Cu-O bonds. We find that, while underdoped crystals (x=0.105, 0.13) show anomalous temperature dependence, similar to the case of optimally doped system (x=0.15), overdoped crystal (x=0.20) does not reveal such anomaly. Correlated Debye-Waller factor (DWF) of the Cu-O bonds (distance broadening) has been used as an order parameter to determine characteristic local displacements in the CuO sub 2 plane. The amplitude of temperature dependent step-like increase in the DWF at low temperature decreases with increasing doping. It has been discussed that decreasing electron-lattice interaction with increasing doping, shown by angle resolved photoemission measurements, is closely related to the evolving anomalous local CuO sub 2 distortion and charge inho...

  10. Magnetic polarization and two-phonon states

    International Nuclear Information System (INIS)

    Tsoneva, N.; Stoyanov, Ch.; Grinberg, M.; Vdovin, A.

    1997-01-01

    Influence of magnetic core polarization on properties of 2 - member of two-phonon quintet of states 2 1 + x 3 1 - is analyzed. Like for recently identified lowest 1 - member of this quintet, an excitation probability of 2 - state is strongly affected by polarization of the nucleus

  11. Few-body experiments with polarized beams and polarized targets

    International Nuclear Information System (INIS)

    Simmons, J.E.

    1983-01-01

    A survey is presented concerning recent polarization experiments in the elastic p-d, p- 3 He, and p- 4 He systems. Mention is made of selected neutron experiments. The nominal energy range is 10 to 1000 MeV. Recent results and interpretations of the p-d system near 10 MeV are discussed. New experiments on the energy dependence of back angle p-d tensor polarization are discussed with respect to resolution of discrepancies and difficulty of theoretical interpretation. Progress is noted concerning multiple scattering interpretation of forward p-d deuteron polarization. Some new results are presented concerning the p- 3 He system and higher energy p- 4 He polarization experiments. 52 references

  12. Precessing deuteron polarization

    International Nuclear Information System (INIS)

    Sitnik, I.M.; Volkov, V.I.; Kirillov, D.A.; Piskunov, N.M.; Plis, Yu.A.

    2002-01-01

    The feasibility of the acceleration in the Nuclotron of deuterons polarized in the horizontal plane is considered. This horizontal polarization is named precessing polarization. The effects of the main magnetic field and synchrotron oscillations are included. The precessing polarization is supposed to be used in studying the polarization parameters of the elastic dp back-scattering and other experiments

  13. Use of the Strong Collision Model to Calculate Spin Relaxation

    Science.gov (United States)

    Wang, D.; Chow, K. H.; Smadella, M.; Hossain, M. D.; MacFarlane, W. A.; Morris, G. D.; Ofer, O.; Morenzoni, E.; Salman, Z.; Saadaoui, H.; Song, Q.; Kiefl, R. F.

    The strong collision model is used to calculate spin relaxation of a muon or polarized radioactive nucleus in contact with a fluctuating environment. We show that on a time scale much longer than the mean time between collisions (fluctuations) the longitudinal polarization decays exponentially with a relaxation rate equal to a sum of Lorentzians-one for each frequency component in the static polarization function ps(t).

  14. The origin of radio pulsar polarization

    Science.gov (United States)

    Dyks, J.

    2017-12-01

    Polarization of radio pulsar profiles involves a number of poorly understood, intriguing phenomena, such as the existence of comparable amounts of orthogonal polarization modes (OPMs), strong distortions of polarization angle (PA) curves into shapes inconsistent with the rotating vector model (RVM), and the strong circular polarization V which can be maximum (instead of zero) at the OPM jumps. It is shown that the comparable OPMs and large V result from a coherent addition of phase-delayed waves in natural propagation modes, which are produced by a linearly polarized emitted signal. The coherent mode summation implies opposite polarization properties to those known from the incoherent case, in particular, the OPM jumps occur at peaks of V, whereas V changes sign at a maximum linear polarization fraction L/I. These features are indispensable to interpret various observed polarization effects. It is shown that statistical properties of emission and propagation can be efficiently parametrized in a simple model of coherent mode addition, which is successfully applied to complex polarization phenomena, such as the stepwise PA curve of PSR B1913+16 and the strong PA distortions within core components of pulsars B1933+16 and B1237+25. The inclusion of coherent mode addition opens the possibility for a number of new polarization effects, such as inversion of relative modal strength, twin minima in L/I coincident with peaks in V, 45° PA jumps in weakly polarized emission, and loop-shaped core PA distortions. The empirical treatment of the coherency of mode addition makes it possible to advance the understanding of pulsar polarization beyond the RVM model.

  15. Structure-dependent degradation of polar compounds in weathered oils observed by atmospheric pressure photo-ionization hydrogen/deuterium exchange ultrahigh resolution mass spectrometry

    Energy Technology Data Exchange (ETDEWEB)

    Islam, Ananna; Kim, Donghwi [Kyungpook National University, Department of Chemistry, Daegu 702-701 (Korea, Republic of); Yim, Un Hyuk; Shim, Won Joon [Oil and POPs Research Group, Korea Institute of Ocean Science and Technology, KIOST, Geoje 656-834 (Korea, Republic of); Kim, Sunghwan, E-mail: sunghwank@knu.ac.kr [Kyungpook National University, Department of Chemistry, Daegu 702-701 (Korea, Republic of); Green Nano Center, Department of Chemistry, Daegu 702-701 (Korea, Republic of)

    2015-10-15

    Highlights: • We examined source crude oil and weathered oils from M/V Hebei accident. • APPI hydrogen/deuterium exchange ultrahigh mass spectrometry was applied. • N{sub 1} class compounds with 2° and/or 3° amine decrease in larger scale than pyridines. • Preferential degradation of nitrogen-containing compounds was confirmed. • Significant increase in S{sub 1}O{sub 1} compounds was observed as the weathering proceeds. - Abstract: The resin fractions of fresh mixtures of three oils spilled during the M/V Hebei Spirit oil spill, as well as weathered oils collected at weathering stages II and IV from the oil spill site were analyzed and compared by atmospheric pressure photo-ionization hydrogen/deuterium exchange mass spectrometry (HDX MS). The significantly decreased abundance of N{sup +}· and [N − H + D]{sup +} ions suggested that secondary and tertiary amine-containing compounds were preferentially degraded during the early stage of weathering. [N + H]{sup +} and [N + D]{sup +} ions previously attributed to pyridine-type compounds degraded more slowly than secondary and tertiary amine-containing compounds. The preferential degradation of nitrogen-containing compounds was confirmed by photo-degradation experiments using 15 standard compounds. In addition, significant increases of [S{sub 1}O{sub 1} + H]{sup +} and [S{sub 1}O{sub 1} + D]{sup +} ions with higher DBE values were observed from fresh oil mixtures as compared to stages II and IV samples, and that could be linked with the decrease of higher DBE compounds of the S{sub 1} class. This study presented convincing arguments and evidence demonstrating that secondary and tertiary amines were more vulnerable to photo-degradation than compounds containing pyridine, and hence, preferential degradation depending on chemical structures must be considered in the production of hazardous or toxic components.

  16. Structure-dependent degradation of polar compounds in weathered oils observed by atmospheric pressure photo-ionization hydrogen/deuterium exchange ultrahigh resolution mass spectrometry

    International Nuclear Information System (INIS)

    Islam, Ananna; Kim, Donghwi; Yim, Un Hyuk; Shim, Won Joon; Kim, Sunghwan

    2015-01-01

    Highlights: • We examined source crude oil and weathered oils from M/V Hebei accident. • APPI hydrogen/deuterium exchange ultrahigh mass spectrometry was applied. • N 1 class compounds with 2° and/or 3° amine decrease in larger scale than pyridines. • Preferential degradation of nitrogen-containing compounds was confirmed. • Significant increase in S 1 O 1 compounds was observed as the weathering proceeds. - Abstract: The resin fractions of fresh mixtures of three oils spilled during the M/V Hebei Spirit oil spill, as well as weathered oils collected at weathering stages II and IV from the oil spill site were analyzed and compared by atmospheric pressure photo-ionization hydrogen/deuterium exchange mass spectrometry (HDX MS). The significantly decreased abundance of N + · and [N − H + D] + ions suggested that secondary and tertiary amine-containing compounds were preferentially degraded during the early stage of weathering. [N + H] + and [N + D] + ions previously attributed to pyridine-type compounds degraded more slowly than secondary and tertiary amine-containing compounds. The preferential degradation of nitrogen-containing compounds was confirmed by photo-degradation experiments using 15 standard compounds. In addition, significant increases of [S 1 O 1 + H] + and [S 1 O 1 + D] + ions with higher DBE values were observed from fresh oil mixtures as compared to stages II and IV samples, and that could be linked with the decrease of higher DBE compounds of the S 1 class. This study presented convincing arguments and evidence demonstrating that secondary and tertiary amines were more vulnerable to photo-degradation than compounds containing pyridine, and hence, preferential degradation depending on chemical structures must be considered in the production of hazardous or toxic components

  17. Polare maskuliniteter

    Directory of Open Access Journals (Sweden)

    Marit Anne Hauan

    2012-05-01

    Full Text Available In this paper my aim is to read and understand the journal of Gerrit de Veer from the last journey of William Barents to the Arctic Regions in 1596 and the journal of captain Junge on his hunting trip from Tromsø to Svalbard in 1834.It is nearly 240 years between this to voyages. The first journal is known as the earliest report from the arctic era. Gerrit de Veer adds instructive copper engravings to his text and give us insight in the crews meeting with this new land. Captain Junges journal is found together with his dead crew in a house in a fjord nearby Ny-Ålesund and has no drawings, but word. Both of these journals may be read as sources of the knowledge and understanding of the polar region. They might also unveil the ideas of how to deal with and survive under the challenges that is given. In addition one can ask if the sources can tell us more about how men describe their challenges. Can the way they expressed themselves in the journals give us an understanding of masculinity? And not least help us to create good questions of the change in the ideas of masculinities which is said to follow the change in understanding of the wilderness.

  18. Modeling optical and UV polarization of AGNs. IV. Polarization timing

    Science.gov (United States)

    Rojas Lobos, P. A.; Goosmann, R. W.; Marin, F.; Savić, D.

    2018-03-01

    Context. Optical observations cannot resolve the structure of active galactic nuclei (AGN), and a unified model for AGN was inferred mostly from indirect methods, such as spectroscopy and variability studies. Optical reverberation mapping allowed us to constrain the spatial dimension of the broad emission line region and thereby to measure the mass of supermassive black holes. Recently, reverberation was also applied to the polarized signal emerging from different AGN components. In principle, this should allow us to measure the spatial dimensions of the sub-parsec reprocessing media. Aim. We conduct numerical modeling of polarization reverberation and provide theoretical predictions for the polarization time lag induced by different AGN components. The model parameters are adjusted to the observational appearance of the Seyfert 1 galaxy NGC 4151. Methods: We modeled scattering-induced polarization and tested different geometries for the circumnuclear dust component. Our tests included the effects of clumpiness and different dust prescriptions. To further extend the model, we also explored the effects of additional ionized winds stretched along the polar direction, and of an equatorial scattering ring that is responsible for the polarization angle observed in pole-on AGN. The simulations were run using a time-dependent version of the STOKES code. Results: Our modeling confirms the previously found polarization characteristics as a function of the observer`s viewing angle. When the dust adopts a flared-disk geometry, the lags reveal a clear difference between type 1 and type 2 AGN. This distinction is less clear for a torus geometry where the time lag is more sensitive to the geometry and optical depth of the inner surface layers of the funnel. The presence of a scattering equatorial ring and ionized outflows increased the recorded polarization time lags, and the polar outflows smooths out dependence on viewing angle, especially for the higher optical depth of the

  19. Flexoelectric charge separation and size dependent piezoelectricity in dielectric solids

    Energy Technology Data Exchange (ETDEWEB)

    Ma, Wenhui [Department of Physics, Shantou University, Shantou, Guangdong 515063 (China)

    2010-01-15

    Flexoelectric charge separation and the associated size dependent piezoelectricity are investigated in centrosymmetric dielectric solids. Direct piezoelectricity can exist as external mechanical stress is applied to non-piezoelectric dielectrics with shapes such as truncated pyramids, due to elastic strain gradient induced flexoelectric polarization. Effective piezoelectric coefficient is analyzed in truncated pyramids, which is strongly enhanced by size reduction and depends on flexoelectricity, elastic compliance, and aspect ratio of the non-piezoelectric dielectric solids. (Abstract Copyright [2010], Wiley Periodicals, Inc.)

  20. Polarization Monitoring of the Lens System JVAS B0218+357

    Directory of Open Access Journals (Sweden)

    Andrew Biggs

    2017-10-01

    Full Text Available Monitoring of the lens system JVAS B0218+357 with the Fermi Gamma-ray Space Telescope measured a different time delay to that derived from radio observations. We have re-analysed three months of archival Very Large Array data to produce variability curves with an average sampling of one epoch per day in total flux, polarized flux and polarization position angle (PPA at 15, 8.4 and 5 GHz. The variability is particularly strong in polarized flux. Dense sampling and improved subtraction of the Einstein ring has allowed us to produce superior variability curves and a preliminary analysis has resulted in a time delay (11.5 days which agrees well with the γ -ray value. Both images of 0218+357 are subject to strong Faraday rotation and depolarization as a result of the radio waves passing through the interstellar medium of the spiral lens galaxy. Our data reveal frequency-dependent variations in the PPA that are different in each image and which must therefore result from variable Faraday rotation in the lens galaxy on timescales of a few days. Our analysis has revealed systematic errors in the polarization position angle measurements that strongly correlate with hour angle. Although we have been able to correct for these, we caution that all VLA polarization observations are potentially affected.

  1. Testing strong interaction theories

    International Nuclear Information System (INIS)

    Ellis, J.

    1979-01-01

    The author discusses possible tests of the current theories of the strong interaction, in particular, quantum chromodynamics. High energy e + e - interactions should provide an excellent means of studying the strong force. (W.D.L.)

  2. Linearly and circularly polarized laser photoinduced molecular order in azo dye doped polymer films

    Directory of Open Access Journals (Sweden)

    Saad Bendaoud

    2017-01-01

    Full Text Available Photo-induced behavior of Azo Disperse one (AZD1 doped Poly(Methyl MethAcrylate (PMMA using both linear and circular polarized light is studied. The anisotropy is not erased by the circular polarization light. The circular polarization light combined with relatively long lifetime of the cis state in azo dye doped polymers activate all transverse directions of the angular hole burning through the spot in the film inducing anisotropy. Under circular polarized light, there is no orientation perpendicularly to the helex described by the rotating electric field vector, trans molecules reorients in the propagation direction of the pump beam. The polarization state of the probe beam after propagation through the pumped spot depends strongly on the angle of incidence of both pump and probe beams on the input face. In the case where circular polarized pump and probe beams are under the same angle of incidence, the probe beam “sees” anisotropic film as if it is isotropic. Results of this work shows the possibility to reorient azobenzene-type molecules in two orthogonal directions using alternately linearly and circularly polarized beams.

  3. Study of proton polarization in charge exchange process on optically oriented sodium atoms

    International Nuclear Information System (INIS)

    Zelenskij, A.N.; Kokhanovskij, S.A.

    1984-01-01

    Using high-power adjustable dye lasers for electron spin orientation in a charge-exchange target enables to significantly increase the proton polarization efficiency. A device is described that permits to avoid growth of the polarized proton beam emittance in a charge-exchange process in a strong magnetic field. The devise main feature is the use of an intensive source of neutral hydrogen atoms and the presence of a helium additional charge-exchange target which actualy is a proton ''source''. The helium charge-exchange cell is placed in the same magnetic field of a solenoid where a cell with oriented sodium is placed, a polarized electron being captured by a proton in the latter cell. In this case the beam at the solenoid inlet and outlet is in a neutral state; emittance growth related to the effect of end magnetic fields is not observed. The device after all prouduces polarized protons, their polarization degree is measured and the effect of various factors on polarization degree is studied. The description of the laser source and laser system is given. Measurement results have shown the beam intensity of neutral 7 keV atoms which passed through a polarizer to be 2 mA. The proton current doesn't depend. On the beeld fin the region of chrge exchange for the 8 kGs magnetic field. The degree of sodium polarization was 80% and polarized proton current approximately 70 μA at a temperature of the polarized sodium cell corresponding to the density of sodium vapar approximately 3x10 13 at/cm 2

  4. Magnetic Field Perturbations from Currents in the Dark Polar Regions During Quiet Geomagnetic Conditions

    DEFF Research Database (Denmark)

    Friis-Christensen, Eigil; Finlay, Chris; Hesse, M.

    2017-01-01

    In the day-side sunlit polar ionosphere the varying and IMF dependent convection creates strong ionospheric currents even during quiet geomagnetic conditions. Observations during such times are often excluded when using satellite data to model the internal geomagneticmain field. Observations from...... the night-side or local winter during quiet conditions are, however, also influenced by variations in the IMF. In this paper we briefly review the large scale features of the ionospheric currents in the polar regions with emphasis on the current distribution during undisturbed conditions. We examine...

  5. Observation of self-polarization in BSA protected Au20 clusters

    Science.gov (United States)

    Swain, D. K.; Narzary, A.; Singh, A. K.; Chandra, A.; Nagasawa, T.; Yamamoto, S.; Mitsuishi, M.; Rath, S.

    2017-11-01

    Bovine serum albumin (BSA)-protected gold clusters (atomicity ˜ 20), prepared using a wet chemical route, show strong dipolar radiative transition with a gap energy of 1.93 eV due to the high oscillator strength, as confirmed by the emission studies. Self-arrangement of the clusters with fixed atomicity yields a low dispersive dielectric and electric self-polarization nature. The electrical hysteresis loop measurements returned a remanent polarization of 0.05 μC cm-2, which can be correlated with the dipolar orientation (activation energy ˜ 45.32 meV), originating from the structure-dependent deformation of the charge density.

  6. Shotgun lipidomics on a LTQ Orbitrap mass spectrometer by successive switching between acquisition polarity modes

    DEFF Research Database (Denmark)

    Schuhmann, K.; Almeida, R.; Baumert, M.

    2012-01-01

    Topdown shotgun lipidomics relies on direct infusion of total lipid extracts into a high-resolution tandem mass spectrometer and implies that individual lipids are recognized by their accurately determined m/z. Lipid ionization efficiency and detection specificity strongly depend on the acquisition...... polarity, and therefore it is beneficial to analyze lipid mixtures in both positive and negative modes. Hybrid LTQ Orbitrap mass spectrometers are widely applied in topdown lipidomics; however, rapid polarity switching was previously unfeasible because of the severe and immediate degradation of mass...

  7. Polarization-independent, differential-phase-shift, quantum-key distribution system using upconversion detectors.

    Science.gov (United States)

    Iwai, Yuki; Honjo, Toshimori; Inoue, Kyo; Kamada, Hidehiko; Nishida, Yoshiki; Tadanaga, Osamu; Asobe, Masaki

    2009-05-15

    We propose and demonstrate a polarization-independent, differential-phase-shift, quantum-key distribution system with upconversion detectors. Even though the detectors have polarization dependency, use of alternative polarization modulation and a two-bit delay interferometer achieves polarization-insensitive operation. In an experiment, sifted key bits were polarization-independently generated over 50 km fiber.

  8. Dipolar collisions of polar molecules in the quantum regime.

    Science.gov (United States)

    Ni, K-K; Ospelkaus, S; Wang, D; Quéméner, G; Neyenhuis, B; de Miranda, M H G; Bohn, J L; Ye, J; Jin, D S

    2010-04-29

    Ultracold polar molecules offer the possibility of exploring quantum gases with interparticle interactions that are strong, long-range and spatially anisotropic. This is in stark contrast to the much studied dilute gases of ultracold atoms, which have isotropic and extremely short-range (or 'contact') interactions. Furthermore, the large electric dipole moment of polar molecules can be tuned using an external electric field; this has a range of applications such as the control of ultracold chemical reactions, the design of a platform for quantum information processing and the realization of novel quantum many-body systems. Despite intense experimental efforts aimed at observing the influence of dipoles on ultracold molecules, only recently have sufficiently high densities been achieved. Here we report the experimental observation of dipolar collisions in an ultracold molecular gas prepared close to quantum degeneracy. For modest values of an applied electric field, we observe a pronounced increase in the loss rate of fermionic potassium-rubidium molecules due to ultracold chemical reactions. We find that the loss rate has a steep power-law dependence on the induced electric dipole moment, and we show that this dependence can be understood in a relatively simple model based on quantum threshold laws for the scattering of fermionic polar molecules. In addition, we directly observe the spatial anisotropy of the dipolar interaction through measurements of the thermodynamics of the dipolar gas. These results demonstrate how the long-range dipolar interaction can be used for electric-field control of chemical reaction rates in an ultracold gas of polar molecules. Furthermore, the large loss rates in an applied electric field suggest that creating a long-lived ensemble of ultracold polar molecules may require confinement in a two-dimensional trap geometry to suppress the influence of the attractive, 'head-to-tail', dipolar interactions.

  9. Charge transport in non-polar and semi-polar III-V nitride heterostructures

    International Nuclear Information System (INIS)

    Konar, Aniruddha; Verma, Amit; Fang, Tian; Zhao, Pei; Jana, Raj; Jena, Debdeep

    2012-01-01

    Compared to the intense research focus on the optical properties, the transport properties in non-polar and semi-polar III-nitride semiconductors remain relatively unexplored to date. The purpose of this paper is to discuss charge-transport properties in non-polar and semi-polar orientations of GaN in a comparative fashion to what is known for transport in polar orientations. A comprehensive approach is adopted, starting from an investigation of the differences in the electronic bandstructure along different polar orientations of GaN. The polarization fields along various orientations are then discussed, followed by the low-field electron and hole mobilities. A number of scattering mechanisms that are specific to non-polar and semi-polar GaN heterostructures are identified, and their effects are evaluated. Many of these scattering mechanisms originate due to the coupling of polarization with disorder and defects in various incarnations depending on the crystal orientation. The effect of polarization orientation on carrier injection into quantum-well light-emitting diodes is discussed. This paper ends with a discussion of orientation-dependent high-field charge-transport properties including velocity saturation, instabilities and tunneling transport. Possible open problems and opportunities are also discussed. (paper)

  10. Polarized electron sources

    Energy Technology Data Exchange (ETDEWEB)

    Prepost, R. [Univ. of Wisconsin, Madison, WI (United States)

    1994-12-01

    The fundamentals of polarized electron sources are described with particular application to the Stanford Linear Accelerator Center. The SLAC polarized electron source is based on the principle of polarized photoemission from Gallium Arsenide. Recent developments using epitaxially grown, strained Gallium Arsenide cathodes have made it possible to obtain electron polarization significantly in excess of the conventional 50% polarization limit. The basic principles for Gallium and Arsenide polarized photoemitters are reviewed, and the extension of the basic technique to strained cathode structures is described. Results from laboratory measurements of strained photocathodes as well as operational results from the SLAC polarized source are presented.

  11. Polar vortex evolution during Northern Hemispheric winter 2004/05

    Directory of Open Access Journals (Sweden)

    T. Chshyolkova

    2007-06-01

    Full Text Available As a part of the project "Atmospheric Wave Influences upon the Winter Polar Vortices (0–100 km" of the CAWSES program, data from meteor and Medium Frequency radars at 12 locations and MetO (UK Meteorological Office global assimilated fields have been analyzed for the first campaign during the Northern Hemispheric winter of 2004/05. The stratospheric state has been described using the conventional zonal mean parameters as well as Q-diagnostic, which allows consideration of the longitudinal variability. The stratosphere was cold during winter of 2004/05, and the polar vortex was relatively strong during most of the winter with relatively weak disturbances occurring at the end of December and the end of January. For this winter the strongest deformation with the splitting of the polar vortex in the lower stratosphere was observed at the end of February. Here the results show strong latitudinal and longitudinal differences that are evident in the stratospheric and mesospheric data sets at different stations. Eastward winds are weaker and oscillations with planetary wave periods have smaller amplitudes at more poleward stations. Accordingly, the occurrence, time and magnitude of the observed reversal of the zonal mesospheric winds associated with stratospheric disturbances depend on the local stratospheric conditions. In general, compared to previous years, the winter of 2004/05 could be characterized by weak planetary wave activity at stratospheric and mesospheric heights.

  12. Polarized electroluminescence from silicon nanostructures

    Energy Technology Data Exchange (ETDEWEB)

    Bagraev, Nikolay; Danilovsky, Eduard; Gets, Dmitry; Klyachkin, Leonid; Kudryavtsev, Andrey; Kuzmin, Roman; Malyarenko, Anna [Ioffe Physical-Technical Institute, 194021 St. Petersburg (Russian Federation); Mashkov, Vladimir [St. Petersburg State Polytechnical University, 195251 St. Petersburg (Russian Federation)

    2012-05-15

    We present the first findings of the circularly polarized electroluminescence (CPEL) from silicon nanostructures which are the p-type ultra-narrow silicon quantum well (Si-QW) confined by {delta}-barriers heavily doped with boron. The CPEL dependences on the forward current and lateral electric field show the circularly polarized light emission which appears to be caused by the exciton recombination through the negative-U dipole boron centers at the Si-QW-{delta}-barriers interface with the assistance of phosphorus donors. (copyright 2012 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim) (orig.)

  13. Waves in strong centrifugal fields: dissipationless gas

    Science.gov (United States)

    Bogovalov, S. V.; Kislov, V. A.; Tronin, I. V.

    2015-04-01

    Linear waves are investigated in a rotating gas under the condition of strong centrifugal acceleration of the order 106 g realized in gas centrifuges for separation of uranium isotopes. Sound waves split into three families of the waves under these conditions. Dispersion equations are obtained. The characteristics of the waves strongly differ from the conventional sound waves on polarization, velocity of propagation and distribution of energy of the waves in space for two families having frequencies above and below the frequency of the conventional sound waves. The energy of these waves is localized in rarefied region of the gas. The waves of the third family were not specified before. They propagate exactly along the rotational axis with the conventional sound velocity. These waves are polarized only along the rotational axis. Radial and azimuthal motions are not excited. Energy of the waves is concentrated near the wall of the rotor where the density of the gas is largest.

  14. Magnetic properties of strongly asymmetric nuclear matter

    International Nuclear Information System (INIS)

    Kutschera, M.; Wojcik, W.

    1988-01-01

    We investigate stability of neutron matter containing a small proton admixture with respect to spin fluctuations. We establish conditions under which strongly asymmetric nuclear matter could acquire a permanent magnetization. It is shown that if the protons are localized, the system becomes unstable to spin fluctuations for arbitrarily weak proton-neutron spin interactions. For non-localized protons there exists a threshold value of the spin interaction above which the system can develop a spontaneous polarization. 12 refs., 2 figs. (author)

  15. Circularly polarized microwaves for magnetic resonance study in the GHz range: Application to nitrogen-vacancy in diamonds

    Energy Technology Data Exchange (ETDEWEB)

    Mrózek, M., E-mail: mariusz.mrozek@uj.edu.pl; Rudnicki, D. S.; Gawlik, W. [Institute of Physics, Jagiellonian University, Lojasiewicza 11, 30-348 Krakow (Poland); Mlynarczyk, J. [Department of Electronics, AGH University of Science and Technology, Mickiewicza 30, 30-059 Krakow (Poland)

    2015-07-06

    The ability to create time-dependent magnetic fields of controlled polarization is essential for many experiments with magnetic resonance. We describe a microstrip circuit that allows us to generate strong magnetic field at microwave frequencies with arbitrary adjusted polarization. The circuit performance is demonstrated by applying it to an optically detected magnetic resonance and Rabi nutation experiments in nitrogen-vacancy color centers in diamond. Thanks to high efficiency of the proposed microstrip circuit and degree of circular polarization of 85%; it is possible to address the specific spin states of a diamond sample using a low power microwave generator. The circuit may be applied to a wide range of magnetic resonance experiments with a well-controlled polarization of microwaves.

  16. Generating highly polarized nuclear spins in solution using dynamic nuclear polarization

    DEFF Research Database (Denmark)

    Wolber, J.; Ellner, F.; Fridlund, B.

    2004-01-01

    A method to generate strongly polarized nuclear spins in solution has been developed, using Dynamic Nuclear Polarization (DNP) at a temperature of 1.2K, and at a field of 3.354T, corresponding to an electron spin resonance frequency of 94GHz. Trityl radicals are used to directly polarize 13C...... and other low-γ nuclei. Subsequent to the DNP process, the solid sample is dissolved rapidly with a warm solvent to create a solution of molecules with highly polarized nuclear spins. Two main applications are proposed: high-resolution liquid state NMR with enhanced sensitivity, and the use...

  17. Influence of the initial angular distribution on strong-field molecular dissociation

    Science.gov (United States)

    Yu, Youliang; Zeng, Shuo; Hernández, J. V.; Wang, Yujun; Esry, B. D.

    2016-08-01

    We study few-cycle, strong-field dissociation of aligned H2+ by solving the time-dependent Schrödinger equation including rotation. We examine the dependence of the final angular distribution, the kinetic energy release spectrum, and the total dissociation yield on the initial nuclear angular distribution. In particular, we look at the dependence on the relative angle θ0 between the laser polarization and the symmetry axis of a well-aligned initial distribution, as well as the dependence on the delay between the "pump" pulse that prepares the alignment and the few-cycle probe pulse. Surprisingly, we find the dissociation probability for θ0=90∘ can be appreciable even though the transitions involved are purely parallel. We therefore address the limits of the commonly held "ball-and-stick" picture for molecules in intense fields as well as the validity of the axial recoil approximation.

  18. Strongly Correlated Topological Insulators

    Science.gov (United States)

    2016-02-03

    Strongly Correlated Topological Insulators In the past year, the grant was used for work in the field of topological phases, with emphasis on finding...surface of topological insulators. In the past 3 years, we have started a new direction, that of fractional topological insulators. These are materials...in which a topologically nontrivial quasi-flat band is fractionally filled and then subject to strong interactions. The views, opinions and/or

  19. Anomalous electrodynamics of neutral pion matter in strong magnetic fields

    Energy Technology Data Exchange (ETDEWEB)

    Brauner, Tomáš [Department of Mathematics and Natural Sciences, University of Stavanger,N-4036 Stavanger (Norway); Kadam, Saurabh V. [Indian Institute of Science Education and Research (IISER),Pune 411008 (India)

    2017-03-03

    The ground state of quantum chromodynamics in sufficiently strong external magnetic fields and at moderate baryon chemical potential is a chiral soliton lattice (CSL) of neutral pions https://arxiv.org/abs/1609.05213. We investigate the interplay between the CSL structure and dynamical electromagnetic fields. Our main result is that in presence of the CSL background, the two physical photon polarizations and the neutral pion mix, giving rise to two gapped excitations and one gapless mode with a nonrelativistic dispersion relation. The nature of this mode depends on the direction of its propagation, interpolating between a circularly polarized electromagnetic wave https://www.doi.org/10.1103/PhysRevD.93.085036 and a neutral pion surface wave, which in turn arises from the spontaneously broken translation invariance. Quite remarkably, there is a neutral-pion-like mode that remains gapped even in the chiral limit, in seeming contradiction to the Goldstone theorem. Finally, we have a first look at the effect of thermal fluctuations of the CSL, showing that even the soft nonrelativistic excitation does not lead to the Landau-Peierls instability. However, it leads to an anomalous contribution to pressure that scales with temperature and magnetic field as T{sup 5/2}(B/f{sub π}){sup 3/2}.

  20. Managing light polarization via plasmon-molecule interactions within an asymmetric metal nanoparticle trimer

    International Nuclear Information System (INIS)

    Shegai, Timur; Li, Zhipeng; Zhang, Zhenyu; Xu, Hongxing; Haran, Gilad

    2008-01-01

    The interaction of light with metal nanoparticles leads to novel phenomena mediated by surface plasmon excitations. In this paper we use single molecules to characterize the interaction of surface plasmons with light, and show that such interaction can strongly modulate the polarization of the emitted light. The simplest nanostructures that enable such polarization modulation are asymmetric silver nanocrystal trimers, where individual Raman scattering molecules are located in the gap between two of the nanoparticles. The third particle breaks the dipolar symmetry of the two-particle junction, generating a wavelength-dependent polarization pattern. Indeed, the scattered light becomes elliptically polarized and its intensity pattern is rotated in the presence of the third particle. We use a combination of spectroscopic observations on single molecules, scanning electron microscope imaging, and generalized Mie theory calculations to provide a full picture of the effect of particles on the polarization of the emitted light. Furthermore, our theoretical analysis allows us to show that the observed phenomenon is very sensitive to the size of the trimer particles and their relative position, suggesting future means for precise control of light polarization on the nanoscale.

  1. Radio wave propagation in the Martian polar deposits: models and implications for radar sounding.

    Science.gov (United States)

    Ilyushin, Ya. A.

    In the present study the propagation of electromagnetic waves in the northern polar ice sheet of Mars is considered Several different scenarios of the structure of the polar deposits and composition of the ice compatible with previously published observational data are proposed Both analytical and numerical simulations of ultra wide band chirp radar pulse propagating through the cap are performed Approximate approach based on the non-coherent theory of the radiative transfer in layered media has been applied to the problem of the propagation of radar pulses in the polar caps Both 1D and 2D and 3D geometry applicable to the orbital and landed radar instruments are studied The side clutter and phase distortions of the signal are also addressed analyzed The possibilities of retrieval of the geological information depending on transparency of the polar cap for radio waves are discussed If the polar cap is relatively transparent the echo from the base of the sheet should be clearly distinctive and interpretable in terms of basal topography of the cap In the case of moderate optical thickness coherent basal echo is corrupted by strong multiple scattering in the layered structure However some conclusions about basal conditions could be made from the signals for example the subglacial lakes may be detected Finally optically thick polar caps prevent any sounding of the base so only the medium itself can be characterized by GPR measurements e g the impurity content in the ice can be found Ilyushin Y A R Seu

  2. POLAR - novel hard X-ray polarimeter for Gamma Ray Bursts

    Science.gov (United States)

    Hajdas, Wojtek

    Our present knowledge of the Gamma Ray Bursts GRBs - the most powerful explosions in the universe after the Big Bang - links them with a birth of the black holes and localize at cosmological distances. There is also a strong evidence relating some of them with Supernovae and thus with gravitational waves. Despite of such significant role of GRBs only little is known about their mechanisms and progenitors. Existing theories still have troubles describing bursts prompt emissions while predictions of the photon polarization show large divergences. On the observational side there are just few isolated measurements of the hard X-ray polarization affected by large experimental uncertainties. Nevertheless, it became clear that determining the GRB polarization could be an ultimate step for understanding their genuine nature. To participate in this task we propose POLAR - novel instrument for hard X-ray and low energy gamma ray polarimetry. The instrument goal is to perform highly precise polarization studies from a very large number of GRBs. Measurements of the linear polarization in the GRB prompt emission at photon energies from 5 keV to 500 keV will be carried out using continuous observations of the sky. Our calculations showed that for several bursts per year the experimental precision will reach a 1 sigma level of 3 per cent. For the strongest events it will be possible to study polarization as a function of energy achieving much more detailed view of the emitting system structure. POLAR uses a uniform array of 1600 weakly shielded plastic detectors coupled with the new multi-anode photo-multipliers. The polarization measurement is based on Compton scattering and relies on detection of fast coincidences between plastic scintillator bars. The total mass (28 kg) and power requirements (30 W) are very moderate. POLAR has relatively small dimensions and it was designed to be not only non-intrusive but also highly adaptable. The qualification model is currently under

  3. Strong Cosmic Censorship

    Science.gov (United States)

    Isenberg, James

    2017-01-01

    The Hawking-Penrose theorems tell us that solutions of Einstein's equations are generally singular, in the sense of the incompleteness of causal geodesics (the paths of physical observers). These singularities might be marked by the blowup of curvature and therefore crushing tidal forces, or by the breakdown of physical determinism. Penrose has conjectured (in his `Strong Cosmic Censorship Conjecture`) that it is generically unbounded curvature that causes singularities, rather than causal breakdown. The verification that ``AVTD behavior'' (marked by the domination of time derivatives over space derivatives) is generically present in a family of solutions has proven to be a useful tool for studying model versions of Strong Cosmic Censorship in that family. I discuss some of the history of Strong Cosmic Censorship, and then discuss what is known about AVTD behavior and Strong Cosmic Censorship in families of solutions defined by varying degrees of isometry, and discuss recent results which we believe will extend this knowledge and provide new support for Strong Cosmic Censorship. I also comment on some of the recent work on ``Weak Null Singularities'', and how this relates to Strong Cosmic Censorship.

  4. Geographical Income Polarization

    DEFF Research Database (Denmark)

    Azhar, Hussain; Jonassen, Anders Bruun

    inter municipal income inequality. Counter factual simulations show that rising property prices to a large part explain the rise in polarization. One side-effect of polarization is tendencies towards a parallel polarization of residence location patterns, where low skilled individuals tend to live......In this paper we estimate the degree, composition and development of geographical income polarization based on data at the individual and municipal level in Denmark from 1984 to 2002. Rising income polarization is reconfirmed when applying new polarization measures, the driving force being greater...

  5. Electron Beam Polarization Measurement Using Touschek Lifetime Technique

    Energy Technology Data Exchange (ETDEWEB)

    Sun, Changchun; /Duke U., DFELL; Li, Jingyi; /Duke U., DFELL; Mikhailov, Stepan; /Duke U., DFELL; Popov, Victor; /Duke U., DFELL; Wu, Wenzhong; /Duke U., DFELL; Wu, Ying; /Duke U., DFELL; Chao, Alex; /SLAC; Xu, Hong-liang; /Hefei, NSRL; Zhang, Jian-feng; /Hefei, NSRL

    2012-08-24

    Electron beam loss due to intra-beam scattering, the Touschek effect, in a storage ring depends on the electron beam polarization. The polarization of an electron beam can be determined from the difference in the Touschek lifetime compared with an unpolarized beam. In this paper, we report on a systematic experimental procedure recently developed at Duke FEL laboratory to study the radiative polarization of a stored electron beam. Using this technique, we have successfully observed the radiative polarization build-up of an electron beam in the Duke storage ring, and determined the equilibrium degree of polarization and the time constant of the polarization build-up process.

  6. Synthesis of a polar ordered oxynitride perovskite

    Science.gov (United States)

    Vadapoo, Rajasekarakumar; Ahart, Muhtar; Somayazulu, Maddury; Holtgrewe, Nicholas; Meng, Yue; Konopkova, Zuzana; Hemley, Russell J.; Cohen, R. E.

    2017-06-01

    For decades, numerous attempts have been made to produce polar oxynitride perovskites, where some of the oxygen is replaced by nitrogen, but a polar ordered oxynitride has never been demonstrated. Caracas and Cohen [Appl. Phys. Lett. 91, 092902 (2007), 10.1063/1.2776370] studied possible ordered polar oxynitrides within density-functional theory (DFT) and found a few candidates that were predicted to be insulating and at least metastable. YSi O2N stood out with huge predicted polarization and nonlinear optic coefficients. In this study, we demonstrate the synthesis of perovskite-structured YSi O2N by using a combination of a diamond-anvil cell and in situ laser-heating techniques. Subsequent in situ x-ray diffraction, second-harmonic generation, and Raman-scattering measurements confirm that it is polar and a strong nonlinear optical material, with structure and properties similar to those predicted by DFT.

  7. Synthesis of a polar ordered oxynitride perovskite

    Energy Technology Data Exchange (ETDEWEB)

    Vadapoo, Rajasekarakumar; Ahart, Muhtar; Somayazulu, Maddury; Holtgrewe, Nicholas; Meng, Yue; Konopkova, Zuzana; Hemley, Russell J.; Cohen, R. E.

    2017-06-01

    For decades, numerous attempts have been made to produce polar oxynitride perovskites, where some of the oxygen is replaced by nitrogen, but a polar ordered oxynitride has never been demonstrated. Caracas and Cohen [Appl. Phys. Lett. 91, 092902 (2007)] studied possible ordered polar oxynitrides within density-functional theory (DFT) and found a few candidates that were predicted to be insulating and at least metastable. YSi O 2 N stood out with huge predicted polarization and nonlinear optic coefficients. In this study, we demonstrate the synthesis of perovskite-structured YSi O 2 N by using a combination of a diamond-anvil cell and in situ laser-heating techniques. Subsequent in situ x-ray diffraction, second-harmonic generation, and Raman-scattering measurements confirm that it is polar and a strong nonlinear optical material, with structure and properties similar to those predicted by DFT.

  8. Induction of transverse polarity by blue light: an all-or-none response.

    Science.gov (United States)

    Nick, P; Schafer, E

    1991-10-01

    Phototropic stimulation induces a spatial memory. This was inferred from experiments with maize (Zea mays L.) coleoptiles involving opposing blue-light pulses, separated by variable time intervals, and rotation on a horizontal clinostat (Nick and Schafer, 1988b, Planta 175, 380-388). In those experiments, individual seedlings either curved towards the first or towards the second pulse, or they remained straight. Bending, if it occurred, seemed to be an all-or-none response. Intermediates, i.e. plants, bending only weakly, were not observed. In the first part of the present study it was attempted to create such intermediates. For this purpose the strength of the first, inducing, and the second, opposing, pulse was varied. The result was complex: (i) Individual seedlings maintained the all-or-none expression of spatial memory. (ii) However, on the level of the whole population, the time intervals at which a given response type dominated depended on the fluence ratio. (iii) Furthermore, the final curvature was determined by the fluence ratio. These results are discussed in terms of a blue-light-induced transverse polarity. This polarity initiates from a labile precursor, which can be reoriented by an opposing stimulation (indicated by the strong bending towards the second pulse). The strong curvatures towards the first pulse over long time intervals reveal that, eventually, the blue-light-induced transverse polarity becomes stabilised and thus immune to the counterpulse. In the second part of the study, the relation between phototropic transduction and transverse polarity was characterised by a phenomenological approach involving the following points: (i) Sensory adaptation for induction of transverse polarity disappears with a time course similar to that for phototropic sensory adaptatation. (ii) The fluence response for induction of transverse polarity is a saturation curve and not bell-shaped like the curve for phototropism (iii) For strong counterpulses and long

  9. Large polarization gradients and temperature-stable responses in compositionally-graded ferroelectrics

    Science.gov (United States)

    Damodaran, Anoop R.; Pandya, Shishir; Qi, Yubo; Hsu, Shang-Lin; Liu, Shi; Nelson, Christopher; Dasgupta, Arvind; Ercius, Peter; Ophus, Colin; Dedon, Liv R.; Agar, Josh C.; Lu, Hongling; Zhang, Jialan; Minor, Andrew M.; Rappe, Andrew M.; Martin, Lane W.

    2017-05-01

    A range of modern applications require large and tunable dielectric, piezoelectric or pyroelectric response of ferroelectrics. Such effects are intimately connected to the nature of polarization and how it responds to externally applied stimuli. Ferroelectric susceptibilities are, in general, strongly temperature dependent, diminishing rapidly as one transitions away from the ferroelectric phase transition (TC). In turn, researchers seek new routes to manipulate polarization to simultaneously enhance susceptibilities and broaden operational temperature ranges. Here, we demonstrate such a capability by creating composition and strain gradients in Ba1-xSrxTiO3 films which result in spatial polarization gradients as large as 35 μC cm-2 across a 150 nm thick film. These polarization gradients allow for large dielectric permittivity with low loss (εr~775, tan δ<0.05), negligible temperature-dependence (13% deviation over 500 °C) and high-dielectric tunability (greater than 70% across a 300 °C range). The role of space charges in stabilizing polarization gradients is also discussed.

  10. Polar catastrophe at the MgO(100)/SnO2(110) interface

    KAUST Repository

    Albar, Arwa

    2016-11-14

    First principles calculations, based on density functional theory, are used to investigate the structural and electronic properties of the epitaxial MgO(100)/SnO2(110) interface of wide band gap insulators. Depending on the interface termination, nonmagnetic metallic and half-metallic interface states are observed. The formation of these states is explained by a polar catastrophe model for nonpolar-polar interfaces. Strong lattice distortions and buckling develop in SnO2, which influence the interface properties as the charge discontinuity is partially screened. Already a single unit cell of SnO2 is sufficient to drive the polar catastrophe scenario. © 2016 The Royal Society of Chemistry.

  11. Scalar-vector soliton fiber laser mode-locked by nonlinear polarization rotation.

    Science.gov (United States)

    Wu, Zhichao; Liu, Deming; Fu, Songnian; Li, Lei; Tang, Ming; Zhao, Luming

    2016-08-08

    We report a passively mode-locked fiber laser by nonlinear polarization rotation (NPR), where both vector and scalar soliton can co-exist within the laser cavity. The mode-locked pulse evolves as a vector soliton in the strong birefringent segment and is transformed into a regular scalar soliton after the polarizer within the laser cavity. The existence of solutions in a polarization-dependent cavity comprising a periodic combination of two distinct nonlinear waves is first demonstrated and likely to be applicable to various other nonlinear systems. For very large local birefringence, our laser approaches the operation regime of vector soliton lasers, while it approaches scalar soliton fiber lasers under the condition of very small birefringence.

  12. Photon polarization effects in b →sγg decay

    International Nuclear Information System (INIS)

    Aliev, T.M.; Pak, N.K.; Rekalo, M.P.

    1995-01-01

    We analyze the polarization properties of photons which are produced in the unpolarized b-quark decay, b → sγg. Using the structure function formalism we carry out a general analysis of the polarization characteristics of γ in terms of the standard Stokes parameters. The expressions for five independent structure functions are constructed in terms of the weak magnetic transition form factors of the vertices b → sγ and b → sg. Numerical calculations of the Stokes parameters and various differential distributions for b → sγg are performed for the two-Higgs doublet model (2HDM). We studied the dependences of all these characteristics to the model parameters. These results were compared with the Standard Model predictions for different top quark masses. Strong sensitivity of the Stokes parameters, which defines the linear photon polarization, to the model is demonstrated. (orig.)

  13. Theoretical analysis of polarized structure functions

    International Nuclear Information System (INIS)

    Altarelli, G.; ); Ball, R.D.; Forte, S.; Ridolfi, G.

    1998-01-01

    We review the analysis of polarized structure function data using perturbative QCD and NLO We use the most recent experimental data to obtain updated results for polarized parton distributions, first moments and the strong coupling. We also discuss several theoretical issues involving in this analysis and in the interpretation of its results. Finally, we compare our results with other similar analyses in the recent literature. (author)

  14. Theoretical Analysis of Polarized Structure Functions

    CERN Document Server

    Altarelli, Guido; Forte, Stefano; Ridolfi, G

    1998-01-01

    We review the analysis of polarized structure function data using perturbative QCD at next-to-leading order. We use the most recent experimental data to obtain updated results for polarized parton distributions, first moments and the strong coupling. We also discuss several theoretical issues involved in this analysis and in the interpretation of its results. Finally, we compare our results with other similar analyses in the recent literature.

  15. Polarization and Conflict: Theoretical and Empirical Issues

    OpenAIRE

    Esteban, Joan; Schneider, Gerald

    2008-01-01

    Recent formal and statistical research in political science and economics strongly indicates that various forms of political and social polarization increase the risk of violent conflict within and between nation states. The articles collected for this issue explore this crucial relationship and provide answers to a variety of topics: First, contributors address how institutions and other contingent factors mediate the conflict potential in polarized societies. Second, this special issue comp...

  16. Polarization and ellipticity of high-order harmonics from aligned molecules generated by linearly polarized intense laser pulses

    International Nuclear Information System (INIS)

    Le, Anh-Thu; Lin, C. D.; Lucchese, R. R.

    2010-01-01

    We present theoretical calculations for polarization and ellipticity of high-order harmonics from aligned N 2 , CO 2 , and O 2 molecules generated by linearly polarized lasers. Within the rescattering model, the two polarization amplitudes of the harmonics are determined by the photo-recombination amplitudes for photons emitted with polarization parallel or perpendicular to the direction of the same returning electron wave packet. Our results show clear species-dependent polarization states, in excellent agreement with experiments. We further note that the measured polarization ellipse of the harmonic furnishes the needed parameters for a 'complete' experiment in molecules.

  17. Switching the response of metasurfaces in polarization standing waves

    OpenAIRE

    Fang, X.; MacDonald, K.F.; Zheludev, N.I.

    2015-01-01

    We demonstrate experimentally that standing waves of polarization, as opposed to intensity, can be engaged to coherently control light-matter interactions in planar photonic nanostructures, presenting unique opportunities for all-optical data processing and polarization-dependent molecular spectroscopy. Such waves, formed by counter-propagating (linear or circular) orthogonally polarized beams can, for example, uniquely detect polarization conversion, planar chirality and related asymmetric t...

  18. Polarized Light Corridor Demonstrations.

    Science.gov (United States)

    Davies, G. R.

    1990-01-01

    Eleven demonstrations of light polarization are presented. Each includes a brief description of the apparatus and the effect demonstrated. Illustrated are strain patterns, reflection, scattering, the Faraday Effect, interference, double refraction, the polarizing microscope, and optical activity. (CW)

  19. Ehrenfest's theorem and the validity of the two-step model for strong-field ionization

    DEFF Research Database (Denmark)

    Shvetsov-Shilovskiy, Nikolay; Dimitrovski, Darko; Madsen, Lars Bojer

    2013-01-01

    with situations where the ensemble average of the force deviates considerably from the force calculated at the average position of the trajectories of the ensemble. We identify the general trends for the applicability of the semiclassical model in terms of intensity, ellipticity, and wavelength of the laser pulse......By comparison with the solution of the time-dependent Schrödinger equation we explore the validity of the two-step semiclassical model for strong-field ionization in elliptically polarized laser pulses. We find that the discrepancy between the two-step model and the quantum theory correlates...

  20. Strong Arcwise Connectedness

    OpenAIRE

    Espinoza, Benjamin; Gartside, Paul; Kovan-Bakan, Merve; Mamatelashvili, Ana

    2012-01-01

    A space is `n-strong arc connected' (n-sac) if for any n points in the space there is an arc in the space visiting them in order. A space is omega-strong arc connected (omega-sac) if it is n-sac for all n. We study these properties in finite graphs, regular continua, and rational continua. There are no 4-sac graphs, but there are 3-sac graphs and graphs which are 2-sac but not 3-sac. For every n there is an n-sac regular continuum, but no regular continuum is omega-sac. There is an omega-sac ...

  1. Abortion: Strong's counterexamples fail

    DEFF Research Database (Denmark)

    Di Nucci, Ezio

    2009-01-01

    This paper shows that the counterexamples proposed by Strong in 2008 in the Journal of Medical Ethics to Marquis's argument against abortion fail. Strong's basic idea is that there are cases--for example, terminally ill patients--where killing an adult human being is prima facie seriously morally......'s scenarios have some valuable future or admitted that killing them is not seriously morally wrong. Finally, if "valuable future" is interpreted as referring to objective standards, one ends up with implausible and unpalatable moral claims....

  2. Polarized Moessbauer transitions

    International Nuclear Information System (INIS)

    Barb, D.

    1975-01-01

    Theoretical aspects of the emission, absorption and scattering of polarized gamma rays are reviewed for a general case of combined magnetic and electric hyperfine interactions; various possibilities of obtaining polarized gamma sources are described and examples are given of the applications of Moessbauer spectroscopy with polarized gamma rays in solving problems of solid state physics. (A.K.)

  3. A strong comeback

    International Nuclear Information System (INIS)

    Marier, D.

    1992-01-01

    This article presents the results of a financial rankings survey which show a strong economic activity in the independent energy industry. The topics of the article include advisor turnover, overseas banks, and the increase in public offerings. The article identifies the top project finance investors for new projects and restructurings and rankings for lenders

  4. Polarized semi-inclusive deep-inelastic scattering on transversely and longitudinally polarized nucleons at HERMES

    International Nuclear Information System (INIS)

    Hommes, B.

    2005-01-01

    The HERMES experiment has measured double spin asymmetries in the cross section for deep-inelastic scattering of longitudinal polarized positrons off longitudinal polarized hydrogen and deuterium targets. From these asymmetries, based on inclusive and semi-inclusive measurements, polarized quark distributions were extracted as a function of x. Single-spin azimuthal asymmetries in semi-inclusive pion production were measured by the HERMES experiment for the first time, with a transversely polarized hydrogen target. Two different sine-dependencies were extracted which can be related to the quark transversity distribution h q 1 (x) and the Sivers function (Author)

  5. Physics results from polarized DIS

    International Nuclear Information System (INIS)

    Ramsey, G. P.

    1998-01-01

    We have extracted polarized nucleon distributions from recent data at CERN, SLAC and DESY. The flavor-dependent valence and sea quark spin distributions are determined for each experiment. We take into account possible differences in the up and down sea distributions, and assume that the strange sea contribution is suppressed by mass effects. Physics results determined from different experiments are compared, including higher order corrections

  6. Physics results from polarized DIS.

    Energy Technology Data Exchange (ETDEWEB)

    Ramsey, G. P.

    1998-03-23

    We have extracted polarized nucleon distributions from recent data at CERN, SLAC and DESY. The flavor-dependent valence and sea quark spin distributions are determined for each experiment. We take into account possible differences in the up and down sea distributions, and assume that the strange sea contribution is suppressed by mass effects. Physics results determined from different experiments are compared, including higher order corrections.

  7. Computational efficiency improvement with Wigner rotation technique in studying atoms in intense few-cycle circularly polarized pulses

    International Nuclear Information System (INIS)

    Yuan, Minghu; Feng, Liqiang; Lü, Rui; Chu, Tianshu

    2014-01-01

    We show that by introducing Wigner rotation technique into the solution of time-dependent Schrödinger equation in length gauge, computational efficiency can be greatly improved in describing atoms in intense few-cycle circularly polarized laser pulses. The methodology with Wigner rotation technique underlying our openMP parallel computational code for circularly polarized laser pulses is described. Results of test calculations to investigate the scaling property of the computational code with the number of the electronic angular basis function l as well as the strong field phenomena are presented and discussed for the hydrogen atom

  8. Strongly correlating liquids and their isomorphs

    OpenAIRE

    Pedersen, Ulf R.; Gnan, Nicoletta; Bailey, Nicholas P.; Schröder, Thomas B.; Dyre, Jeppe C.

    2010-01-01

    This paper summarizes the properties of strongly correlating liquids, i.e., liquids with strong correlations between virial and potential energy equilibrium fluctuations at constant volume. We proceed to focus on the experimental predictions for strongly correlating glass-forming liquids. These predictions include i) density scaling, ii) isochronal superposition, iii) that there is a single function from which all frequency-dependent viscoelastic response functions may be calculated, iv) that...

  9. Optimization of strong and weak coordinates

    NARCIS (Netherlands)

    Swart, M.; Bickelhaupt, F.M.

    2006-01-01

    We present a new scheme for the geometry optimization of equilibrium and transition state structures that can be used for both strong and weak coordinates. We use a screening function that depends on atom-pair distances to differentiate strong coordinates from weak coordinates. This differentiation

  10. Climate change and the increasing impact of polar bears on bird populations

    Directory of Open Access Journals (Sweden)

    Jouke eProp

    2015-03-01

    Full Text Available The Arctic is becoming warmer at a high rate, and contractions in the extent of sea ice are currently changing the habitats of marine top-predators dependent on ice. Polar bears (Ursus maritimus depend on sea ice for hunting seals. For these top-predators, longer ice-free seasons are hypothesized to force the bears to hunt for alternative terrestrial food, such as eggs from colonial breeding birds. We analyzed time-series of polar bear observations at four locations on Spitsbergen (Svalbard and one in east Greenland. Summer occurrence of polar bears, measured as the probability of encountering bears and the number of days with bear presence, has increased significantly from the 1970/80s to the present. The shifts in polar bear occurrence coincided with trends for shorter sea ice seasons and less sea ice during the spring in the study area. This resulted in a strong inverse relationship between the probability of bear encounters on land and the length of the sea ice season. Within ten years after their first appearance on land, polar bears had advanced their arrival dates by almost 30 days. Direct observations of nest predation showed that polar bears may severely affect reproductive success of the barnacle goose (Branta leucopsis, common eider (Somateria mollissima and glaucous gull (Larus hyperboreus. Nest predation was strongest in years when the polar bears arrived well before hatch, with more than 90% of all nests being predated. The results are similar to findings from Canada, and large-scale processes, such as climate and subsequent habitat changes, are pinpointed as the most likely drivers in various parts of the Arctic. We suggest that the increasing, earlier appearance of bears on land in summer reflects behavioral adaptations by a small segment of the population to cope with a reduced hunting range on sea ice. This exemplifies how behavioral adaptations may contribute to the cascading effects of climate change.

  11. Emission polarization study on quartz and calcite.

    Science.gov (United States)

    Vincent, R. K.

    1972-01-01

    Calculation of the spectral emission polarization of quartz and calcite polished plates for observation angles of 20 and 70 deg by the substitution of complex index of refraction values for each mineral into Fresnel's equations. The emission polarization is shown to be quite wavelength-dependent, demonstrating that selected narrow or medium-width spectral bands exhibit a significantly higher percentage of polarization than a broad spectral band for these two minerals. Field measurements with a broadband infrared radiometer yield polarizations on the order of 2% for a coarse-grained granite rock and beach sand (both quartz-rich). This implies that a more sensitive detector with a selected medium-width filter may be capable of measuring emission polarization accurately enough to make this parameter useful as a remote sensing tool for discrimination among rocks on the basis of texture.

  12. Temperature dependent polarization reversal mechanism in 0.94(Bi1/2Na1/2) TiO3-0.06Ba(Zr0.02Ti0.98)O3 relaxor ceramics

    DEFF Research Database (Denmark)

    Glaum, Julia; Simons, Hugh; Hudspeth, Jessica

    2015-01-01

    The temperature at which the electric field induced long-range ordered ferroelectric state undergoes transition into the short-range ordered relaxor state, TF-R, is commonly defined by the onset of strong dispersion of the dielectric permittivity. However, this combined macroscopic property and s...... associated with different polarization reversal processes. Such diagrams are useful tools for identifying the best operational temperature regimes for a given composition in actuator applications....... and structural investigation of the polarization reversal process in the prototypical lead-free relaxor 0.94(Bi1/2Na1/2)TiO3-0.06Ba(Zr0.02Ti0.98)O3 reveals that an applied electric field can trigger depolarization and onset of relaxor-like behavior well below TF-R. The polarization reversal process can....... These results are concomitant with a continuous ferroelectric to relaxortransition occurring over a broad temperature range, during which mixed behavior is observed. The nature of polarization reversal can be illustrated in electric-field-temperature (E-T) diagrams showing the electric field amplitudes...

  13. An important role of temperature dependent scattering time in understanding the high temperature thermoelectric behavior of strongly correlated system: La0.75Ba0.25CoO3.

    Science.gov (United States)

    Singh, Saurabh; Kumar, Devendra; Pandey, Sudhir K

    2017-03-15

    In the present work, we report the temperature dependent thermopower (α) behavior of La 0.75 Ba 0.25 CoO 3 compound in the temperature range 300-600 K. Using the Heikes formula, the estimated value of α corresponding to high-spin configuration of Co 3+ and Co 4+ ions is found to be  ∼16 [Formula: see text], which is close to the experimental value, ∼13 [Formula: see text], observed at  ∼600 K. The temperature dependent TE behavior of the compound is studied by combining the WIEN2K and BoltzTrap code. The self consistency field calculations show that the compound have ferromagnetic ground state structure. The electronic structure calculations give half metallic characteristic with a small gap of  ∼50 meV for down spin channel. The large and positive value for down spin channel is obtained due to the unique band structure shown by this spin channel. The temperature dependent relaxation time for both the spin-channel charge carriers is considered to study the thermopower data in temperature range 300-600 K. For evaluation of α, almost linear values of [Formula: see text] and a non-linear values of [Formula: see text] are taken into account. By taking the temperature dependent values of relaxation time for both the spin channels, the calculated values of α using two current model are found to be in good agreement with experimental values in the temperature range 300-600 K. At 300 K, the calculated value of electrical conductivity by using the same value of relaxation time, i.e. 0.1 [Formula: see text] 10 -14 seconds for spin-up and [Formula: see text] seconds for spin-dn channel, is found to be equal to the experimentally reported value.

  14. Quantum Hydrodynamical Formulation of Time-Dependent Density Functional Theory for Probing Strong-Field Multiphoton Processes: Application to the Study of High-Order Harmonic Generation of He and Ne in Intense Laser Fields

    Science.gov (United States)

    Roy, A. K.; Chu, Shih-I.

    2002-05-01

    We extend the quantum hydrodynamical (QFD) formulation of time-dependent density functional theory (TDDFT) to the study of multiphoton processes of many-electron atomic systems in intense laser fields (A. K. Roy and S. I. Chu, Phys. Rev. A (in press).). The QFD-TDDFT formulation results in a single generalized nonlinear Schrodinger equation (GNLSE) and includes the many-body effects through a local time-dependent exchange-correlation (xc) potential. The GNLSE is solved by the time- dependent generalized pseudospectral method (X. M. Tong and S.I. Chu, Chem. Phys. 217) (1997) 119. (X. Chu and S. I. Chu, Phys. Rev. A 63) (2001) 023411.. The procedure is applied to the study of multiphoton ionization (MPI) and high harmonic generation (HHG) of He and Ne in intense laser fields. Four different xc energy functionals are used in the study with an aim to explore the roles of exchange and correlation ovn MPI/HHG processes in details ^1.

  15. Optically pumped electron spin polarized targets for use in the production of polarized ion beams

    International Nuclear Information System (INIS)

    Anderson, L.W.

    1979-01-01

    The production of relatively dense electron spin polarized alkali metal vapor targets by optical pumping with intense cw dye lasers is discussed. The target density and electron spin polarization depend on the dye laser intensity and bandwidth, the magnetic field at the target, and the electron spin depolarization time. For example in a magnetic field of 1.5 x 10 3 G, and using 1 W dye laser with a bandwidth of 10 10 Hz one can construct an electron spin polarized Na vapor target with a target thickness of 1.6 x 10 13 atoms/cm 2 and an average electron spin polarization of about 90% even though the Na atoms are completely depolarized at every wall collision. Possible uses of the electron spin polarized targets for the production of intense beams of polarized H - or 3 He - ions are discussed. (orig.)

  16. The Physics of Polarization

    Science.gov (United States)

    Landi Degl'Innocenti, Egidio

    2015-10-01

    The introductory lecture that has been delivered at this Symposium is a condensed version of an extended course held by the author at the XII Canary Island Winter School from November 13 to November 21, 2000. The full series of lectures can be found in Landi Degl'Innocenti (2002). The original reference is organized in 20 Sections that are here itemized: 1. Introduction, 2. Description of polarized radiation, 3. Polarization and optical devices: Jones calculus and Muller matrices, 4. The Fresnel equations, 5. Dichroism and anomalous dispersion, 6. Polarization in everyday life, 7. Polarization due to radiating charges, 8. The linear antenna, 9. Thomson scattering, 10. Rayleigh scattering, 11. A digression on Mie scattering, 12. Bremsstrahlung radiation, 13. Cyclotron radiation, 14. Synchrotron radiation, 15. Polarization in spectral lines, 16. Density matrix and atomic polarization, 17. Radiative transfer and statistical equilibrium equations, 18. The amplification condition in polarized radiative transfer, and 19. Coupling radiative transfer and statistical equilibrium equations.

  17. Strong Electroweak Symmetry Breaking

    CERN Document Server

    Grinstein, Benjamin

    2011-01-01

    Models of spontaneous breaking of electroweak symmetry by a strong interaction do not have fine tuning/hierarchy problem. They are conceptually elegant and use the only mechanism of spontaneous breaking of a gauge symmetry that is known to occur in nature. The simplest model, minimal technicolor with extended technicolor interactions, is appealing because one can calculate by scaling up from QCD. But it is ruled out on many counts: inappropriately low quark and lepton masses (or excessive FCNC), bad electroweak data fits, light scalar and vector states, etc. However, nature may not choose the minimal model and then we are stuck: except possibly through lattice simulations, we are unable to compute and test the models. In the LHC era it therefore makes sense to abandon specific models (of strong EW breaking) and concentrate on generic features that may indicate discovery. The Technicolor Straw Man is not a model but a parametrized search strategy inspired by a remarkable generic feature of walking technicolor,...

  18. Polarization digital holographic microscopy using low-cost liquid crystal polarization rotators

    Science.gov (United States)

    Dovhaliuk, Rostyslav Yu

    2018-02-01

    Polarization imaging methods are actively used to study anisotropic objects. A number of methods and systems, such as imaging polarimeters, were proposed to measure the state of polarization of light that passed through the object. Digital holographic and interferometric approaches can be used to quantitatively measure both amplitude and phase of a wavefront. Using polarization modulation optics, the measurement capabilities of such interference-based systems can be extended to measure polarization-dependent parameters, such as phase retardation. Different kinds of polarization rotators can be used to alternate the polarization of a reference beam. Liquid crystals are used in a rapidly increasing number of different optoelectronic devices. Twisted nematic liquid crystals are widely used as amplitude modulators in electronic displays and light valves or shutter glass. Such devices are of particular interest for polarization imaging, as they can be used as polarization rotators, and due to large-scale manufacturing have relatively low cost. A simple Mach-Zehnder polarized holographic setup that uses modified shutter glass as a polarization rotator is demonstrated. The suggested approach is experimentally validated by measuring retardation of quarter-wave film.

  19. Plasmons in strong superconductors

    International Nuclear Information System (INIS)

    Baldo, M.; Ducoin, C.

    2011-01-01

    We present a study of the possible plasmon excitations that can occur in systems where strong superconductivity is present. In these systems the plasmon energy is comparable to or smaller than the pairing gap. As a prototype of these systems we consider the proton component of Neutron Star matter just below the crust when electron screening is not taken into account. For the realistic case we consider in detail the different aspects of the elementary excitations when the proton, electron components are considered within the Random-Phase Approximation generalized to the superfluid case, while the influence of the neutron component is considered only at qualitative level. Electron screening plays a major role in modifying the proton spectrum and spectral function. At the same time the electron plasmon is strongly modified and damped by the indirect coupling with the superfluid proton component, even at moderately low values of the gap. The excitation spectrum shows the interplay of the different components and their relevance for each excitation modes. The results are relevant for neutrino physics and thermodynamical processes in neutron stars. If electron screening is neglected, the spectral properties of the proton component show some resemblance with the physical situation in high-T c superconductors, and we briefly discuss similarities and differences in this connection. In a general prospect, the results of the study emphasize the role of Coulomb interaction in strong superconductors.

  20. Tunnel magnetoresistance and linear conductance of double quantum dots strongly coupled to ferromagnetic leads

    Energy Technology Data Exchange (ETDEWEB)

    Weymann, Ireneusz, E-mail: weymann@amu.edu.pl [Faculty of Physics, Adam Mickiewicz University, 61-614 Poznań (Poland)

    2015-05-07

    We analyze the spin-dependent linear-response transport properties of double quantum dots strongly coupled to external ferromagnetic leads. By using the numerical renormalization group method, we determine the dependence of the linear conductance and tunnel magnetoresistance on the degree of spin polarization of the leads and the position of the double dot levels. We focus on the transport regime where the system exhibits the SU(4) Kondo effect. It is shown that the presence of ferromagnets generally leads the suppression of the linear conductance due to the presence of an exchange field. Moreover, the exchange field gives rise to a transition from the SU(4) to the orbital SU(2) Kondo effect. We also analyze the dependence of the tunnel magnetoresistance on the double dot levels' positions and show that it exhibits a very nontrivial behavior.

  1. Surface-polarization electrooptic effect in a nematic liquid crystal

    International Nuclear Information System (INIS)

    Lavrentovich, O.D.; Nazarenko, V.G.; Pergamenshchik, V.M.; Sergan, V.V.; Sorokin, V.M.

    1991-01-01

    A new electrooptic effect was observed experimentally in a homeotropic layer of a nematic with a positive anisotropy of the permittivity and of the electrical conductivity. This effect appeared in an external vertical static electric field and was manifested by the appearance of circular or elongated domain structures due to static distortions of the director near the anode or cathode of a cell. The polarity of the effect depended on the nature of an orienting coating. The origin of the effect was the nematic surface polarization which was sufficiently strong (∼10 -2 dyn 1/2 ) to induce an instability even under the conditions where other mechanisms (dielectric, flexoelectric, anisotropic electrohydrodynamic) impeded stability. Special attention was given to the separation of the surface polarization mechanism of the investigated effect from the flexoelectric and isotropic electrodynamic mechanisms. A hierarchy of static structures observed experimentally was clearly accounted for by a theory based on an equilibrium thermodynamic approach allowing for the anisotropic properties and for the real geometry of the system

  2. High antibody-dependent cellular cytotoxicity responses are correlated with strong CD8 T cell viral suppressive activity but not with B57 status in HIV-1 elite controllers.

    Directory of Open Access Journals (Sweden)

    Olivier Lambotte

    Full Text Available The role of Antibody-dependent cellular cytotoxicity (ADCC responses in HIV-1 controllers is still unclear due to the heterogeneity of these patients. We analyzed 67 HIV-1 controllers and found significantly higher levels of ADCC antibodies in controllers versus viremic subjects (p = 0.017. Moreover, multivariate analysis revealed significantly higher ADCC titers in HLA B57- controllers compared to HLA-B57+ ones (p = 0.0086. These data suggest a role for ADCC in immune control of HIV, especially in HLA B57 negative controllers.

  3. How to measure the linear polarization of gluons in unpolarized proton using the heavy-quark pair leptoproduction

    Science.gov (United States)

    Efremov, A. V.; Ivanov, N. Ya.; Teryaev, O. V.

    2018-02-01

    We study the azimuthal cos ⁡ φ and cos ⁡ 2 φ asymmetries in heavy-quark pair leptoproduction, lN →l‧ Q Q bar X, as probes of linearly polarized gluons inside unpolarized proton, where the azimuth φ is the angle between the lepton scattering plane (l ,l‧) and the heavy quark production plane (N , Q). First, we determine the maximal values for the cos ⁡ φ and cos ⁡ 2 φ asymmetries allowed by the photon-gluon fusion with unpolarized gluons; these predictions are large, (√{ 3 } - 1) / 2 and 1/3, respectively. Then we calculate the contribution of the transverse-momentum dependent gluonic counterpart of the Boer-Mulders function, h1⊥g, describing the linear polarization of gluons inside unpolarized proton. Our analysis shows that the maximum values of the azimuthal distributions depend strongly on the gluon polarization; they vary from 0 to 1 depending on h1⊥g. We conclude that the azimuthal cos ⁡ φ and cos ⁡ 2 φ asymmetries in heavy-quark pair leptoproduction are predicted to be large and very sensitive to the contribution of linearly polarized gluons. For this reason, future measurements of the azimuthal distributions in charm and bottom production at the proposed EIC and LHeC colliders seem to be very promising for determination of the linear polarization of gluons inside unpolarized proton.

  4. How to measure the linear polarization of gluons in unpolarized proton using the heavy-quark pair leptoproduction

    Directory of Open Access Journals (Sweden)

    A.V. Efremov

    2018-02-01

    Full Text Available We study the azimuthal cos⁡φ and cos⁡2φ asymmetries in heavy-quark pair leptoproduction, lN→l′QQ¯X, as probes of linearly polarized gluons inside unpolarized proton, where the azimuth φ is the angle between the lepton scattering plane (l,l′ and the heavy quark production plane (N,Q. First, we determine the maximal values for the cos⁡φ and cos⁡2φ asymmetries allowed by the photon–gluon fusion with unpolarized gluons; these predictions are large, (3−1/2 and 1/3, respectively. Then we calculate the contribution of the transverse-momentum dependent gluonic counterpart of the Boer–Mulders function, h1⊥g, describing the linear polarization of gluons inside unpolarized proton. Our analysis shows that the maximum values of the azimuthal distributions depend strongly on the gluon polarization; they vary from 0 to 1 depending on h1⊥g. We conclude that the azimuthal cos⁡φ and cos⁡2φ asymmetries in heavy-quark pair leptoproduction are predicted to be large and very sensitive to the contribution of linearly polarized gluons. For this reason, future measurements of the azimuthal distributions in charm and bottom production at the proposed EIC and LHeC colliders seem to be very promising for determination of the linear polarization of gluons inside unpolarized proton.

  5. Polarization phenomena in quantum chromodynamics

    Energy Technology Data Exchange (ETDEWEB)

    Brodsky, S.J. [Stanford Univ., CA (United States)

    1994-12-01

    The author discusses a number of interrelated hadronic spin effects which test fundamental features of perturbative and nonperturbative QCD. For example, the anomalous magnetic moment of the proton and the axial coupling g{sub A} on the nucleon are shown to be related to each other for fixed proton radius, independent of the form of the underlying three-quark relativistic quark wavefunction. The renormalization scale and scheme ambiguities for the radiative corrections to the Bjorken sum rule for the polarized structure functions can be eliminated by using commensurate scale relations with other observables. Other examples include (a) new constraints on the shape and normalization of the polarized quark and gluon structure functions of the proton at large and small x{sub bj}; (b) consequences of the principle of hadron retention in high x{sub F} inclusive reactions; (c) applications of hadron helicity conservation to high momentum transfer exclusive reactions; and (d) the dependence of nuclear structure functions and shadowing on virtual photon polarization. The author also discusses the implications of a number of measurements which are in striking conflict with leading-twist perturbative QCD predictions, such as the extraordinarily large spin correlation A{sub NN} observed in large angle proton-proton scattering, the anomalously large {rho}{pi} branching ratio of the J/{psi}, and the rapidly changing polarization dependence of both J/{psi} and continuum lepton pair hadroproduction observed at large x{sub F}. The azimuthal angular dependence of the Drell-Yan process is shown to be highly sensitive to the projectile distribution amplitude, the fundamental valence light-cone wavefunction of the hadron.

  6. Maris polarization in neutron-rich nuclei

    Science.gov (United States)

    Shubhchintak; Bertulani, C. A.; Aumann, T.

    2018-03-01

    We present a theoretical study of the Maris polarization effect and its application in quasi-free reactions to assess information on the structure of exotic nuclei. In particular, we explore the dependence of the polarization effect on neutron excess and neutron-skin thickness. We discuss the uncertainties in the calculations of triple differential cross sections and of analyzing powers due the choices of various nucleon-nucleon interactions and optical potentials and the limitations of the method. Our study implies that polarization variables in (p, 2p) reactions in inverse kinematics can be an effective probe of single-particle structure of nuclei in radioactive-beam facilities.

  7. Projective geometry for polarization in geometric quantization

    International Nuclear Information System (INIS)

    Campbell, P.; Dodson, C.T.J.

    1976-12-01

    It is important to know the extent to which the procedure of geometric quantization depends on a choice of polarization of the symplectic manifold that is the classical phase space. Published results have so far been restricted to real and transversal polarizations. Here we also consider these cases by presenting a formulation in terms of projective geometry. It turns out that there is a natural characterization of real transversal polarizations and maps among them using projective concepts. We give explicit constructions for Rsup(2n)

  8. On the thermal properties of polarized nuclear matter

    International Nuclear Information System (INIS)

    Hassan, M.Y.M.; Montasser, S.S.; Ramadan, S.

    1979-08-01

    The thermal properties of polarized nuclear matter are calculated using Skyrme III interaction modified by Dabrowski for polarized nuclear matter. The temperature dependence of the volume, isospin, spin and spin isospin pressure and energies are determined. The temperature, isospin, spin and spin isospin dependence of the equilibrium Fermi momentum is also discussed. (author)

  9. Current density functional theory for optical spectra : A polarization functional

    NARCIS (Netherlands)

    Boeij, P.L. de; Kootstra, F.; Berger, J.A.; Leeuwen, R. van; Snijders, J.G.

    2001-01-01

    In this paper we present a new approach to calculate optical spectra, which for the first time uses a polarization dependent functional within current density functional theory (CDFT), which was proposed by Vignale and Kohn. This polarization dependent functional includes exchange-correlation (xc)

  10. Advantages of polarization experiments at RHIC

    International Nuclear Information System (INIS)

    Underwood, D.G.

    1990-01-01

    We point out various spin experiments that could be done if the polarized beam option is pursued at RHIC. The advantages of RHIC for investigating several current and future physics problems are discussed. In particular, the gluon spin dependent structure function of the nucleon could be measured cleanly and systematically. Relevant experience developed in conjunction with the Fermilab Polarized Beam program is also presented. 8 refs., 2 tabs

  11. The HIP 79977 debris disk in polarized light

    Science.gov (United States)

    Engler, N.; Schmid, H. M.; Thalmann, Ch.; Boccaletti, A.; Bazzon, A.; Baruffolo, A.; Beuzit, J. L.; Claudi, R.; Costille, A.; Desidera, S.; Dohlen, K.; Dominik, C.; Feldt, M.; Fusco, T.; Ginski, C.; Gisler, D.; Girard, J. H.; Gratton, R.; Henning, T.; Hubin, N.; Janson, M.; Kasper, M.; Kral, Q.; Langlois, M.; Lagadec, E.; Ménard, F.; Meyer, M. R.; Milli, J.; Mouillet, D.; Olofsson, J.; Pavlov, A.; Pragt, J.; Puget, P.; Quanz, S. P.; Roelfsema, R.; Salasnich, B.; Siebenmorgen, R.; Sissa, E.; Suarez, M.; Szulagyi, J.; Turatto, M.; Udry, S.; Wildi, F.

    2017-11-01

    density dependence is described by (r/r0)α with a steep (positive) power law index α = 5 inside r0 and a more shallow (negative) index α = -2.5 outside r0. The scattering asymmetry factor lies between g = 0.2 and 0.6 (forward scattering) adopting a scattering-angle dependence for the fractional polarization such as that for Rayleigh scattering. Conclusions: Polarimetric imaging with SPHERE-ZIMPOL of the edge-on debris disk around HIP 79977 provides accurate profiles for the polarized flux. Our data are qualitatively very similar to the case of AU Mic and they confirm that edge-on debris disks have a polarization minimum at a position near the star and a maximum near the projected separation of the main debris belt. The comparison of the polarized flux contrast ratio (Fpol)disk/F∗ with the fractional infrared excess provides strong constraints on the scattering albedo of the dust.

  12. Strongly-correlated ultracold atoms in optical lattices

    International Nuclear Information System (INIS)

    Dao, Tung-Lam

    2008-01-01

    liquids, but also in unusual phases such as the normal state of high-temperature superconductivity with a pseudo gap (leading to a differentiation between nodes and anti-nodes) observed in condensed mater physics. In the second part of this thesis, we have performed theoretical studies of several phases of strongly correlated fermions in optical lattices in the framework of theoretical models such as the Hubbard model. We have implemented and developed analytical methods (Hartree-Fock mean field theory at weak coupling, mapping on a effective spin model at strong coupling) and numerical methods (the dynamic mean field theory approach). This work has led to two particular types of studies. The first one studies the competition between a superfluid phase and a density wave (or phase separation) for fermions with mass imbalance and attractive interaction. We have shown that the superfluid phase is unstable beyond a certain value of the mass ratio, which depends on the interaction. The second study treats a gas with imbalanced populations (polarized gas) with an attractive interaction in a three dimensional optical lattice. The main result is a phase diagram showing the stability of a uniform superfluid phase with polarization (Sarma phase or breached pair phase) in a certain parameter regime. Via an energetic argument, we concluded that the stability of the polarized superfluid phase is due to the reduction of the polarizability and the critical field of the non-polarized superfluid phase. In the strong coupling regime of the Hubbard model, within the DMFT method, we have shown that the formation of the preformed pair in the normal state reduces the polarizability and favors the stability of the breached pair phase. Although some aspects have been addressed in this thesis, many interesting questions still remain open for future work. In the first part, the framework of the novel spectroscopy method established in chapter 2 can allow for different concrete studies of the

  13. Polarized radio emission of an intense active region on the Sun in July 1974 at wavelengths of 1.9; 2.5 and 3.5 cm

    International Nuclear Information System (INIS)

    Bachurin, A.F.; Dvoryashin, A.S.; Eryushev, N.N.; Tsvetkov, L.I.

    1980-01-01

    The circularly polarized radio emission of an intense active region on the Sun (spot group N 96, McMath regions 13043) was considered at the begining of July 1974. The observations were performed with the 22-m radio telescope of the Crimean astrophysical observatory at wavelengths of 1.9; 2.5 and 3.5 cm simultaneously. Main results are: 1. The spectrum of degree of polarization of a local source of radio emission in the 1.9-3.5 cm wavelength range varies appreciably with time. Spectral maximum of degree of polarization displaces towards shorter wavelengths when activity of the sunspot group increases. 2. The degree of polarization of radio emission of the local source varies considerably at wavelengths of 1.9 and 2.5 cm from day to day. At the 3.5 cm wavelength these changes were not observed. Appreciable variations of the degree of polarization can be observed during a time interval of 10-20 min even if radio bursts are not recorded. 3. The sense of polarization of radio emission for comparatively strong bursts, in most cases, coincides with that for a local source. 4. The change of sense of polarization for a burst depending on wavelength is observed on different wavelengths in the 1.9-3.5 cm range. At a fixed wavelength of the range under review, one sense of polarization can change during the burst to the other in a few seconds

  14. Strong-coupling approximations

    International Nuclear Information System (INIS)

    Abbott, R.B.

    1984-03-01

    Standard path-integral techniques such as instanton calculations give good answers for weak-coupling problems, but become unreliable for strong-coupling. Here we consider a method of replacing the original potential by a suitably chosen harmonic oscillator potential. Physically this is motivated by the fact that potential barriers below the level of the ground-state energy of a quantum-mechanical system have little effect. Numerically, results are good, both for quantum-mechanical problems and for massive phi 4 field theory in 1 + 1 dimensions. 9 references, 6 figures

  15. Strong interaction and QFD

    International Nuclear Information System (INIS)

    Ebata, T.

    1981-01-01

    With an assumed weak multiplet structure for bosonic hadrons, which is consistent with the ΔI = 1/2 rule, it is shown that the strong interaction effective hamiltonian is compatible with the weak SU(2) x U(1) gauge transformation. Especially the rho-meson transforms as a triplet under SU(2)sub(w), and this is the origin of the rho-photon analogy. It is also shown that the existence of the non-vanishing Cabibbo angle is a necessary condition for the absence of the exotic hadrons. (orig.)

  16. Strong Coupling Holography

    CERN Document Server

    Dvali, Gia

    2009-01-01

    We show that whenever a 4-dimensional theory with N particle species emerges as a consistent low energy description of a 3-brane embedded in an asymptotically-flat (4+d)-dimensional space, the holographic scale of high-dimensional gravity sets the strong coupling scale of the 4D theory. This connection persists in the limit in which gravity can be consistently decoupled. We demonstrate this effect for orbifold planes, as well as for the solitonic branes and string theoretic D-branes. In all cases the emergence of a 4D strong coupling scale from bulk holography is a persistent phenomenon. The effect turns out to be insensitive even to such extreme deformations of the brane action that seemingly shield 4D theory from the bulk gravity effects. A well understood example of such deformation is given by large 4D Einstein term in the 3-brane action, which is known to suppress the strength of 5D gravity at short distances and change the 5D Newton's law into the four-dimensional one. Nevertheless, we observe that the ...

  17. Incident angle dependence of reactions between graphene and hydrogen atom by molecular dynamics simulation

    International Nuclear Information System (INIS)

    Saito, Seiki; Nakamura, Hiroaki; Ito, Atsushi

    2010-01-01

    Incident angle dependence of reactions between graphene and hydrogen atoms are obtained qualitatively by classical molecular dynamics simulation under the NVE condition with modified Brenner reactive empirical bond order (REBO) potential. Chemical reaction depends on two parameters, i.e., polar angle θ and azimuthal angle φ of the incident hydrogen. From the simulation results, it is found that the reaction rates strongly depend on polar angle θ. Reflection rate becomes larger with increasing θ, and the θ dependence of adsorption rate is also found. The θ dependence is caused by three dimensional structure of the small potential barrier which covers adsorption sites. φ dependence of penetration rate is also found for large θ. (author)

  18. Polar Heat Flow on Io

    Science.gov (United States)

    Veeder, G. J.; Matson, D. L.; Johnson, T. V.; Davies, A. G.; Blaney, D. L.

    2003-01-01

    Recently, Galileo spacecraft data have revealed Io's polar regions to be much warmer than previously expected. This unexpected development came from Photo-Polarimeter Radiometer (PPR) data which show that the minimum night temperatures are in the range of 90-95 K virtually everywhere on Io. The minimum night temperatures show no dependence upon latitude and, when away from the sunset terminator, they show no dependence upon time of night. This is indeed bizarre behavior for surface units which generally had been assumed to be passive with respect to Io's pervasive volcanism. Night temperatures of 90-95 K at high, polar latitudes are particularly hard to explain. Even assuming infinite thermal inertia, at these latitudes there is insufficient sunlight to support these warm night temperatures. Thus, through the process of elimination of other possibilities, we come to the conclusion that these surfaces are volcanically heated. Taking previously passive units and turning them into new sources of heat flow is a radical departure from previous thermophysical model paradigms. However, the geological interpretation is straight forward. We are simply seeing the effect of old, cool lava flows which cover most of the surface of Io but yet have some heat to radiate. Under these new constraints, we have taken on the challenge of formulating a physical model which quantitatively reproduces all of the observations of Io's thermal emission. In the following we introduce a new parametric model which suffices to identify a previously unrecognized polar component of Io's heat flow.

  19. [Review] Polarization and Polarimetry

    Science.gov (United States)

    Trippe, Sascha

    2014-02-01

    Polarization is a basic property of light and is fundamentally linked to the internal geometry of a source of radiation. Polarimetry complements photometric, spectroscopic, and imaging analyses of sources of radiation and has made possible multiple astrophysical discoveries. In this article I review (i) the physical basics of polarization: electromagnetic waves, photons, and parameterizations; (ii) astrophysical sources of polarization: scattering, synchrotron radiation, active media, and the Zeeman, Goldreich-Kylafis, and Hanle effects, as well as interactions between polarization and matter (like birefringence, Faraday rotation, or the Chandrasekhar-Fermi effect); (iii) observational methodology: on-sky geometry, influence of atmosphere and instrumental polarization, polarization statistics, and observational techniques for radio, optical, and X/γ wavelengths; and (iv) science cases for astronomical polarimetry: solar and stellar physics, planetary system bodies, interstellar matter, astrobiology, astronomical masers, pulsars, galactic magnetic fields, gamma-ray bursts, active galactic nuclei, and cosmic microwave background radiation.

  20. Strong piezoelectricity in bioinspired peptide nanotubes.

    Science.gov (United States)

    Kholkin, Andrei; Amdursky, Nadav; Bdikin, Igor; Gazit, Ehud; Rosenman, Gil

    2010-02-23

    We show anomalously strong shear piezoelectric activity in self-assembled diphenylalanine peptide nanotubes (PNTs), indicating electric polarization directed along the tube axis. Comparison with well-known piezoelectric LiNbO(3) and lateral signal calibration yields sufficiently high effective piezoelectric coefficient values of at least 60 pm/V (shear response for tubes of approximately 200 nm in diameter). PNTs demonstrate linear deformation without irreversible degradation in a broad range of driving voltages. The results open up a wide avenue for developing new generations of "green" piezoelectric materials and piezonanodevices based on bioactive tubular nanostructures potentially compatible with human tissue.

  1. Tunable polarization sensitive absorber made of graphene-based hyperbolic metamaterials

    Science.gov (United States)

    Madani, Amir; Babaei, Maryam

    2017-02-01

    Theoretically, the absorption properties of a hyperbolic metamaterial (HMM) slab constructed from graphene-dielectric multilayers are investigated using the transfer matrix method. The effective medium approximation reveals that the graphene-based HMM slab is an anisotropic and homogeneous medium. It is shown that the absorption of the slab depend on the polarization and incidence angle due to the strong anisotropy of the HMMs. The results revealed that the complete absorption is only possible for the TM-polarized waves in a broad region of wavelength. It is found that the region of total absorption can be controlled and tuned using some controlling parameters such as incidence angle, the orientation of the optical axis of the HMM medium and the chemical potential of the graphene monolayers. Finally, the intensity distribution of a TM-polarized Gaussian beam is simulated which verifies the strong absorption of the waves inside the HMM slab. This absorber may have potential applications in the design of tunable filters, polarizers, detectors, photovoltaic devices and so on.

  2. Switchable thulium-doped fiber laser from polarization rotation vector to scalar soliton.

    Science.gov (United States)

    Wu, Zhichao; Fu, Songnian; Jiang, Kai; Song, Jue; Li, Huizi; Tang, Ming; Shum, Ping; Liu, Deming

    2016-10-06

    We experimentally demonstrate switchable temporal soliton generation from a thulium-doped fiber laser (TDFL), using carbon nanotubes as the mode-locker. With the help of residual polarization dependent loss of a wavelength division multiplexer, a weak nonlinear polarization rotation (NPR) effect can be achieved within the laser cavity, which may provide joint contribution for passive mode-locking operation. By finely adjusting the polarization to alter the strength of NPR-based saturable absorption, the TDFL either approaches the operation regime of scalar soliton with strong NPR effect, or generates polarization rotation locked vector soliton (PRLVS) with weak NPR effect. The scalar solitons and PRLVSs possess 3-dB optical spectrum bandwidth of 2.2 nm and 2 nm, pulse-width of 1.8 ps and 2 ps, respectively. Moreover, the PRLVSs demonstrate a typical energy exchange between two polarized components on optical spectra and a period-doubling feature in time domain. Such operation principle can also be used in 1550 nm band fiber lasers and other nonlinear systems.

  3. White-beaked dolphins trapped in the ice and eaten by polar bears

    Directory of Open Access Journals (Sweden)

    Jon Aars

    2015-06-01

    Full Text Available Polar bears (Ursus maritimus depend on sea ice, where they hunt ice-associated seals. However, they are opportunistic predators and scavengers with a long list of known prey species. Here we report from a small fjord in Svalbard, Norwegian High Arctic, a sighting of an adult male polar bear preying on two white-beaked dolphins (Lagenorhynchus albirostris on 23 April 2014. This is the first record of this species as polar bear prey. White-beaked dolphins are frequent visitors to Svalbard waters in summer, but have not previously been reported this far north in early spring. We suggest they were trapped in the ice after strong northerly winds the days before, and possibly killed when forced to surface for air at a small opening in the ice. The bear had consumed most parts of one dolphin. When observed he was in the process of covering the mostly intact second dolphin with snow. Such caching behaviour is generally considered untypical of polar bears. During the following ice-free summer and autumn, at least seven different white-beaked dolphin carcasses were observed in or near the same area. We suggest, based on the area and the degree to which these dolphins had decayed, that they were likely from the same pod and also suffered death due to entrapment in the ice in April. At least six different polar bears were seen scavenging on the carcasses.

  4. Spectral and Angular Degree of Polarization of the Water Leaving Radiance from the Ocean

    Science.gov (United States)

    Gray, D. J.; Gillis, D. B.; Bowles, J. H.; Korwan, D.; Miller, D.; Lamela, G.

    2016-02-01

    The polarization of the light field reflected from the ocean is now being recognized to contain additional information that can aid in the retrieval of biogeochemical properties of the ocean. But there are currently very few remote sensing systems that can take advantage of this information. We have developed a hyperspectral polarimeter to measure the full linear polarization of the ocean reflectance. The polarimeter uses four lenses with calcite polarizers oriented at 0, 45, 90, and 135 degrees relative to horizontal and measures the linear Stokes vector parameters (I, Q, U) over the spectral range from 350 - 950 nm. The degree and angle of polarization were measured in different water types and found to strongly depend on the inherent optical properties of the water, specifically on the single-scatter albedo, but also phase function, and viewing geometry. We show results for different water types as a function of viewing angle relative to nadir and azimuthal angle relative to the sun. We also show the importance of understanding the effects of the atmosphere on the upwelling polarization signal.

  5. Polarization transfer in relativistic magnetized plasmas

    Science.gov (United States)

    Heyvaerts, Jean; Pichon, Christophe; Prunet, Simon; Thiébaut, Jérôme

    2013-04-01

    The polarization transfer coefficients of a relativistic magnetized plasma are derived. These results apply to any momentum distribution function of the particles, isotropic or anisotropic. Particles interact with the radiation either in a non-resonant mode when the frequency of the radiation exceeds their characteristic synchrotron emission frequency or quasi-resonantly otherwise. These two classes of particles contribute differently to the polarization transfer coefficients. For a given frequency, this dichotomy corresponds to a regime change in the dependence of the transfer coefficients on the parameters of the particle's population, since these parameters control the relative weight of the contribution of each class of particles. Our results apply to either regimes as well as the intermediate one. The derivation of the transfer coefficients involves an exact expression of the conductivity tensor of the relativistic magnetized plasma that has not been used hitherto in this context. Suitable expansions valid at frequencies much larger than the cyclotron frequency allow us to analytically perform the summation over all resonances at high harmonics of the relativistic gyrofrequency. The transfer coefficients are represented in the form of two-variable integrals that can be conveniently computed for any set of parameters by using Olver's expansion of high-order Bessel functions. We particularize our results to a number of distribution functions, isotropic, thermal or power law, with different multipolar anisotropies of low order, or strongly beamed. Specifically, earlier exact results for thermal distributions are recovered. For isotropic distributions, the Faraday coefficients are expressed in the form of a one-variable quadrature over energy, for which we provide the kernels in the high-frequency limit and in the asymptotic low-frequency limit. An interpolation formula extending over the full energy range is proposed for these kernels. A similar reduction to a

  6. Polarization feedback laser stabilization

    Science.gov (United States)

    Esherick, P.; Owyoung, A.

    1987-09-28

    A system for locking two Nd:YAG laser oscillators includes an optical path for feeding the output of one laser into the other with different polarizations. Elliptical polarization is incorporated into the optical path so that the change in polarization that occurs when the frequencies coincide may be detected to provide a feedback signal to control one laser relative to the other. 4 figs.

  7. General solution for calculating polarization electric fields in the auroral ionosphere and application examples

    Science.gov (United States)

    Amm, O.; Fujii, R.; VanhamäKi, H.; Yoshikawa, A.; Ieda, A.

    2013-05-01

    We devise an approach to calculate the polarization electric field in the ionosphere, when the ionospheric conductances, the primary (modeled) or the total (measured) electric field, and the Cowling efficiency are given. In contrast to previous studies, our approach is a general solution which is not limited to specific geometrical setups, and all parameters may have any kind of spatial dependence. The solution technique is based on spherical elementary current (vector) systems (SECS). This way, we avoid the need to specify explicit boundary conditions for the searched polarization electric field of its potential which would be required if the problem was solved in a differential equation approach. Instead, we solve an algebraic matrix equation, and the implicit boundary condition that the divergence of the polarization electric field vanishes outside our analysis area is sufficient. In order to illustrate our theory, we then apply it to two simple models of auroral electrodynamic situations, the first being a mesoscale strong conductance enhancement in the early morning sector within a relatively weak southward primary electric field, and a morning sector auroral arc with only a weak conductance enhancement, but a large southward primary electric field at the poleward flank of the arc. While the significance of the polarization electric field for maximum Cowling efficiency is large for the first case, it is rather minor for the second one. Both models show that the polarization electric field effect may not only change the magnitude of the current systems but also their overall geometry. Furthermore, the polarization electric field may extend into regions where the primary electric field is small, thus even dominating the total electric field in these regions. For the first model case, the total Joule heating integrated over the analysis area decreases by a factor of about 4 for maximum Cowling efficiency as compared to the case of vanishing Cowling efficiency

  8. Polarization at SLC

    International Nuclear Information System (INIS)

    Swartz, M.L.

    1988-07-01

    The SLAC Linear Collider has been designed to readily accommodate polarized electron beams. Considerable effort has been made to implement a polarized source, a spin rotation system, and a system to monitor the beam polarization. Nearly all major components have been fabricated. At the current time, several source and polarimeter components have been installed. The installation and commissioning of the entire system will take place during available machine shutdown periods as the commissioning of SLC progresses. It is expected that a beam polarization of 45% will be achieved with no loss in luminosity. 13 refs., 15 figs

  9. LIGO: The strong belief

    CERN Multimedia

    Antonella Del Rosso

    2016-01-01

    Twenty years of designing, building and testing a number of innovative technologies, with the strong belief that the endeavour would lead to a historic breakthrough. The Bulletin publishes an abstract of the Courier’s interview with Barry Barish, one of the founding fathers of LIGO.   The plots show the signals of gravitational waves detected by the twin LIGO observatories at Livingston, Louisiana, and Hanford, Washington. (Image: Caltech/MIT/LIGO Lab) On 11 February, the Laser Interferometer Gravitational-Wave Observatory (LIGO) and Virgo collaborations published a historic paper in which they showed a gravitational signal emitted by the merger of two black holes. These results come after 20 years of hard work by a large collaboration of scientists operating the two LIGO observatories in the US. Barry Barish, Linde Professor of Physics, Emeritus at the California Institute of Technology and former Director of the Global Design Effort for the Internat...

  10. Field theory of polar continua

    International Nuclear Information System (INIS)

    Heinz, C.

    1988-01-01

    A Lagrangian density in the polar space X 1+3+3 depending of the potentials and their derivativs and of the fluxes is introduced. The potentials are then the mechanical and electromagnetic potentials, the potentials of gravity and in the polar space X 1+3+3 the components of affine connection. The fluxes are essentially the tangential motors of the mechanical and electromagnetic world-lines multiplied with the density of mass and electric charge. The Hamilton principle gives, with the in variational calculus usual integrations by part, here done via the theorem of Gauss, the equations of motion and the field equations. The conditions of integrability for these equations are discussed. (author)

  11. Soluble immune complexes shift the TLR-induced cytokine production of distinct polarized human macrophage subsets towards IL-10.

    Directory of Open Access Journals (Sweden)

    Carmen A Ambarus

    Full Text Available BACKGROUND: Costimulation of murine macrophages with immune complexes (ICs and TLR ligands leads to alternative activation. Studies on human myeloid cells, however, indicate that ICs induce an increased pro-inflammatory cytokine production. This study aimed to clarify the effect of ICs on the pro- versus anti-inflammatory profile of human polarized macrophages. MATERIALS AND METHODS: Monocytes isolated from peripheral blood of healthy donors were polarized for four days with IFN-γ, IL-4, IL-10, GM-CSF, M-CSF, or LPS, in the presence or absence of heat aggregated gamma-globulins (HAGGs. Phenotypic polarization markers were measured by flow cytometry. Polarized macrophages were stimulated with HAGGs or immobilized IgG alone or in combination with TLR ligands. TNF, IL-6, IL-10, IL-12, and IL-23 were measured by Luminex and/or RT-qPCR. RESULTS: HAGGs did not modulate the phenotypic polarization and the cytokine production of macrophages. However, HAGGs significantly altered the TLR-induced cytokine production of all polarized macrophage subsets, with the exception of MΦ(IL-4. In particular, HAGGs consistently enhanced the TLR-induced IL-10 production in both classically and alternatively polarized macrophages (M1 and M2. The effect of HAGGs on TNF and IL-6 production was less pronounced and depended on the polarization status, while IL-23p19 and IL-12p35 expression was not affected. In contrast with HAGGs, immobilized IgG induced a strong upregulation of not only IL-10, but also TNF and IL-6. CONCLUSION: HAGGs alone do not alter the phenotype and cytokine production of in vitro polarized human macrophages. In combination with TLR-ligands, however, HAGGs but not immobilized IgG shift the cytokine production of distinct macrophage subsets toward IL-10.

  12. Dual-polarization wavelength conversion of 16-QAM signals in a single silicon waveguide with a lateral p-i-n diode [Invited

    DEFF Research Database (Denmark)

    Da Ros, Francesco; Gajda, Andrzej; Liebig, Erik

    2018-01-01

    with an optical signal-to-noise ratio penalty below 0.7 dB. High-quality converted signals are generated thanks to the low polarization dependence (≤0.5 dB) and the high conversion efficiency (CE) achievable. The strong Kerr nonlinearity in silicon and the decrease of detrimental free-carrier absorption due......A polarization-diversity loop with a silicon waveguide with a lateral p-i-n diode as a nonlinear medium is used to realize polarization insensitive four-wave mixing. Wavelength conversion of seven dual-polarization 16-quadrature amplitude modulation (QAM) signals at 16 GBd is demonstrated...... to the reverse-biased p-i-n diode are key in ensuring high CE levels....

  13. Calculated Hanle transmission and absorption spectra of the 87Rb D1 line with residual magnetic field for arbitrarily polarized light

    International Nuclear Information System (INIS)

    Noh, Heung-Ryoul; Moon, Han Seb

    2010-01-01

    This paper reports a theoretical study on the transmission spectra of an arbitrarily polarized laser beam through a rubidium cell with or without a buffer gas in Hanle-type coherent population trapping (CPT). This study examined how laser polarization, transverse magnetic field, and collisions with buffer gas affects the spectrum. The transmission spectrum due to CPT and the absorption spectrum due to the level crossing absorption (LCA) were calculated according to the laser polarization. The results show that the LCA is strongly dependent on the transverse magnetic field and interaction time of the atoms with a laser light via collisions with the buffer gas. In addition, the spectral shape of the calculated Hanle spectrum is closely related to the direction between the (stray) transverse magnetic field and polarization of the laser.

  14. PREFACE: Strongly correlated electron systems Strongly correlated electron systems

    Science.gov (United States)

    Saxena, Siddharth S.; Littlewood, P. B.

    2012-07-01

    make use of 'small' electrons packed to the highest possible density. These are by definition 'strongly correlated'. For example: good photovoltaics must be efficient optical absorbers, which means that photons will generate tightly bound electron-hole pairs (excitons) that must then be ionised at a heterointerface and transported to contacts; efficient solid state refrigeration depends on substantial entropy changes in a unit cell, with large local electrical or magnetic moments; efficient lighting is in a real sense the inverse of photovoltaics; the limit of an efficient battery is a supercapacitor employing mixed valent ions; fuel cells and solar to fuel conversion require us to understand electrochemistry on the scale of a single atom; and we already know that the only prospect for effective high temperature superconductivity involves strongly correlated materials. Even novel IT technologies are now seen to have value not just for novel function but also for efficiency. While strongly correlated electron systems continue to excite researchers and the public alike due to the fundamental science issues involved, it seems increasingly likely that support for the science will be leveraged by its impact on energy and sustainability. Strongly correlated electron systems contents Strongly correlated electron systemsSiddharth S Saxena and P B Littlewood Magnetism, f-electron localization and superconductivity in 122-type heavy-fermion metalsF Steglich, J Arndt, O Stockert, S Friedemann, M Brando, C Klingner, C Krellner, C Geibel, S Wirth, S Kirchner and Q Si High energy pseudogap and its evolution with doping in Fe-based superconductors as revealed by optical spectroscopyN L Wang, W Z Hu, Z G Chen, R H Yuan, G Li, G F Chen and T Xiang Structural investigations on YbRh2Si2: from the atomic to the macroscopic length scaleS Wirth, S Ernst, R Cardoso-Gil, H Borrmann, S Seiro, C Krellner, C Geibel, S Kirchner, U Burkhardt, Y Grin and F Steglich Confinement of chiral magnetic

  15. Effects of Booster Scraping in Polarized Proton Runs 2006 and 2008

    Energy Technology Data Exchange (ETDEWEB)

    Zhang,S.Y.; Ahrens, L.; Huang, H.; Zeno, K.

    2009-01-02

    Effects of the Booster vertical scraping on the RHIC beam polarization, the RHIC beam emittance, and on the Booster to AGS transfer efficiency and AGS transmission as well, are further studied. In [1], the strong dependence of the RHIC beam polarization and emittance on bunch intensity in proton run 2008 (pp08) is compared with the proton run 2006 (pp06), where the dependence is much weaker. The setting in the AGS Booster, mainly the vertical scraping, is suspected to having played a role in the different patterns in the two runs. In this note, we further study the effects of the Booster vertical scraping on the RHIC beam polarization, and on the RHIC beam emittance as well. With the improvement of the RHIC bunch intensity in mind, the Booster scraping effects on the Booster to AGS transfer (BtA) efficiency and the AGS transmission are also studied. For simplicity and to be more useful, only the RHIC fills after the one-week shutdown in pp06 and the fills using the AGS User 2 in pp08 are shown. For these fills, the machine settings in AGS are similar in pp06 and pp08 runs. Furthermore, this setting might be used for next polarized proton run, at least at the beginning of the run.

  16. Probing strong-field electron-nuclear dynamics of polyatomic molecules using proton motion

    International Nuclear Information System (INIS)

    Markevitch, Alexei N.; Smith, Stanley M.; Levis, Robert J.; Romanov, Dmitri A.

    2007-01-01

    Proton ejection during Coulomb explosion is studied for several structure-related organic molecules (anthracene, anthraquinone, and octahydroanthracene) subjected to 800 nm, 60 fs laser pulses at intensities from 0.50 to 4.0x10 14 W cm -2 . The proton kinetic energy distributions are found to be markedly structure specific. The distributions are bimodal for anthracene and octahydroanthracene and trimodal for anthraquinone. Maximum (cutoff) energies of the distributions range from 50 eV for anthracene to 83 eV for anthraquinone. The low-energy mode (∼10 eV) is most pronounced in octahydroanthracene. The dependence of the characteristic features of the distributions on the laser intensity provides insights into molecular specificity of such strong-field phenomena as (i) nonadiabatic charge localization and (ii) field-mediated restructuring of polyatomic molecules polarized by a strong laser field

  17. High energy physics with polarized beams and targets. [65 papers

    Energy Technology Data Exchange (ETDEWEB)

    Marshak, M L [ed.

    1976-01-01

    Sixty-six papers are presented as a report on conference sessions held from August 23-27, 1976, at Argonne National Laboratory. Topics covered include: (1) strong interactions; (2) weak and electromagnetic interactions; (3) polarized beams; and (4) polarized targets. A separate abstract was prepared for each paper for ERDA Energy Research Abstracts (ERA) and for the INIS Atomindex. (PMA)

  18. Experiment on the melting pressure of spin polarized He3

    DEFF Research Database (Denmark)

    Chapellier, M.; Olsen, M.; Rasmussen, Finn Berg

    1981-01-01

    In liquid He in a Pomeranchuk cell, the melting curve has been observed to be suppressed, presumably in regions with a strong local spin polarization. In the temperature range 30-50 mK the observed suppression was 60-80 kPa. The corresponding local polarization is estimated, in a crude model, to ...

  19. RHIC Polarized proton operation

    International Nuclear Information System (INIS)

    Huang, H.; Ahrens, L.; Alekseev, I.G.; Aschenauer, E.; Atoian, G.; Bai, M.; Bazilevsky, A.; Blaskiewicz, M.; Brennan, J.M.; Brown, K.A.; Bruno, D.; Connolly, R.; Dion, A.; D'Ottavio, T.; Drees, K.A.; Fischer, W.; Gardner, C.; Glenn, J.W.; Gu, X.; Harvey, M.; Hayes, T.; Hoff, L.; Hulsart, R.L.; Laster, J.; Liu, C.; Luo, Y.; MacKay, W.W.; Makdisi, Y.; Marr, G.J.; Marusic, A.; Meot, F.; Mernick, K.; Michnoff, R.; Minty, M.; Montag, C.; Morris, J.; Nemesure, S.; Poblaguev, A.; Ptitsyn, V.; Ranjibar, V.; Robert-Demolaize, G.; Roser, T.; Schmidke, B.; Schoefer, V.; Severino, F.; Smirnov, D.; Smith, K.; Steski, D.; Svirida, D.; Tepikian, S.; Trbojevic, D.; Tsoupas, N.; Tuozzolo, J.E.; Wang, G.; Wilinski, M.; Yip, K.; Zaltsman, A.; Zelenski, A.; Zeno, K.; Zhang, S.Y.

    2011-01-01

    The Relativistic Heavy Ion Collider (RHIC) operation as the polarized proton collider presents unique challenges since both luminosity(L) and spin polarization(P) are important. With longitudinally polarized beams at the experiments, the figure of merit is LP 4 . A lot of upgrades and modifications have been made since last polarized proton operation. A 9 MHz rf system is installed to improve longitudinal match at injection and to increase luminosity. The beam dump was upgraded to increase bunch intensity. A vertical survey of RHIC was performed before the run to get better magnet alignment. The orbit control is also improved this year. Additional efforts are put in to improve source polarization and AGS polarization transfer efficiency. To preserve polarization on the ramp, a new working point is chosen such that the vertical tune is near a third order resonance. The overview of the changes and the operation results are presented in this paper. Siberian snakes are essential tools to preserve polarization when accelerating polarized beams to higher energy. At the same time, the higher order resonances still can cause polarization loss. As seen in RHIC, the betatron tune has to be carefully set and maintained on the ramp and during the store to avoid polarization loss. In addition, the orbit control is also critical to preserve polarization. The higher polarization during this run comes from several improvements over last run. First we have a much better orbit on the ramp. The orbit feedback brings down the vertical rms orbit error to 0.1mm, much better than the 0.5mm last run. With correct BPM offset and vertical realignment, this rms orbit error is indeed small. Second, the jump quads in the AGS improved input polarization for RHIC. Third, the vertical tune was pushed further away from 7/10 snake resonance. The tune feedback maintained the tune at the desired value through the ramp. To calibrate the analyzing power of RHIC polarimeters at any energy above

  20. RHIC Polarized proton operation

    Energy Technology Data Exchange (ETDEWEB)

    Huang, H.; Ahrens, L.; Alekseev, I.G.; Aschenauer, E.; Atoian, G.; Bai, M.; Bazilevsky, A.; Blaskiewicz, M.; Brennan, J.M.; Brown, K.A.; Bruno, D.; Connolly, R.; Dion, A.; D' Ottavio, T.; Drees, K.A.; Fischer, W.; Gardner, C.; Glenn, J.W.; Gu, X.; Harvey, M.; Hayes, T.; Hoff, L.; Hulsart, R.L.; Laster, J.; Liu, C.; Luo, Y.; MacKay, W.W.; Makdisi, Y.; Marr, G.J.; Marusic, A.; Meot, F.; Mernick, K.; Michnoff, R,; Minty, M.; Montag, C.; Morris, J.; Nemesure, S.; Poblaguev, A.; Ptitsyn, V.; Ranjibar, V.; Robert-Demolaize, G.; Roser, T.; J.; Severino, F.; Schmidke, B.; Schoefer, V.; Severino, F.; Smirnov, D.; Smith, K.; Steski, D.; Svirida, D.; Tepikian, S.; Trbojevic, D.; Tsoupas, N.; Tuozzolo, J. Wang, G.; Wilinski, M.; Yip, K.; Zaltsman, A.; Zelenski, A.; Zeno, K.; Zhang, S.Y.

    2011-03-28

    The Relativistic Heavy Ion Collider (RHIC) operation as the polarized proton collider presents unique challenges since both luminosity(L) and spin polarization(P) are important. With longitudinally polarized beams at the experiments, the figure of merit is LP{sup 4}. A lot of upgrades and modifications have been made since last polarized proton operation. A 9 MHz rf system is installed to improve longitudinal match at injection and to increase luminosity. The beam dump was upgraded to increase bunch intensity. A vertical survey of RHIC was performed before the run to get better magnet alignment. The orbit control is also improved this year. Additional efforts are put in to improve source polarization and AGS polarization transfer efficiency. To preserve polarization on the ramp, a new working point is chosen such that the vertical tune is near a third order resonance. The overview of the changes and the operation results are presented in this paper. Siberian snakes are essential tools to preserve polarization when accelerating polarized beams to higher energy. At the same time, the higher order resonances still can cause polarization loss. As seen in RHIC, the betatron tune has to be carefully set and maintained on the ramp and during the store to avoid polarization loss. In addition, the orbit control is also critical to preserve polarization. The higher polarization during this run comes from several improvements over last run. First we have a much better orbit on the ramp. The orbit feedback brings down the vertical rms orbit error to 0.1mm, much better than the 0.5mm last run. With correct BPM offset and vertical realignment, this rms orbit error is indeed small. Second, the jump quads in the AGS improved input polarization for RHIC. Third, the vertical tune was pushed further away from 7/10 snake resonance. The tune feedback maintained the tune at the desired value through the ramp. To calibrate the analyzing power of RHIC polarimeters at any energy above

  1. Strong gauge boson scattering at the LHC

    CERN Document Server

    Rindani, S.D.

    2009-01-01

    In the standard model with electroweak symmetry breaking through the Higgs mechanism, electroweak gauge-boson scattering amplitudes are large if the Higgs boson is heavy, and electroweak gauge interactions become strong. In theories with electroweak symmetry breaking through alternative mechanisms, there could be a strongly interacting gauge sector, possibly with resonances in an accessible energy region. In general, the scattering of longitudinally polarized massive gauge bosons can give information on the mechanism of spontaneous symmetry breaking. At energies below the symmetry breaking scale, the equivalence theorem relates the scattering amplitudes to those of the "would-be" Goldstone modes. In the absence of Higgs bosons, unitarity would be restored by some new physics which can be studied through WW scattering. Some representatives models are discussed. Isolating WW scattering at a hadron collider from other contributions involving W emission from parton lines needs a good understanding of the backgrou...

  2. John Strong (1941 - 2006)

    CERN Multimedia

    Wickens, F

    Our friend and colleague John Strong was cruelly taken from us by a brain tumour on Monday 31st July, a few days before his 65th birthday John started his career working with a group from Westfield College, under the leadership of Ted Bellamy. He obtained his PhD and spent the early part of his career on experiments at Rutherford Appleton Laboratory (RAL), but after the early 1970s his research was focussed on experiments in CERN. Over the years he made a number of notable contributions to experiments in CERN: The Omega spectrometer adopted a system John had originally developed for experiments at RAL using vidicon cameras to record the sparks in the spark chambers; He contributed to the success of NA1 and NA7, where he became heavily involved in the electronic trigger systems; He was responsible for the second level trigger system for the ALEPH detector and spent five years leading a team that designed and built the system, which ran for twelve years with only minor interventions. Following ALEPH he tur...

  3. Stirring Strongly Coupled Plasma

    CERN Document Server

    Fadafan, Kazem Bitaghsir; Rajagopal, Krishna; Wiedemann, Urs Achim

    2009-01-01

    We determine the energy it takes to move a test quark along a circle of radius L with angular frequency w through the strongly coupled plasma of N=4 supersymmetric Yang-Mills (SYM) theory. We find that for most values of L and w the energy deposited by stirring the plasma in this way is governed either by the drag force acting on a test quark moving through the plasma in a straight line with speed v=Lw or by the energy radiated by a quark in circular motion in the absence of any plasma, whichever is larger. There is a continuous crossover from the drag-dominated regime to the radiation-dominated regime. In the crossover regime we find evidence for significant destructive interference between energy loss due to drag and that due to radiation as if in vacuum. The rotating quark thus serves as a model system in which the relative strength of, and interplay between, two different mechanisms of parton energy loss is accessible via a controlled classical gravity calculation. We close by speculating on the implicati...

  4. Strong-interaction nonuniversality

    International Nuclear Information System (INIS)

    Volkas, R.R.; Foot, R.; He, X.; Joshi, G.C.

    1989-01-01

    The universal QCD color theory is extended to an SU(3) 1 direct product SU(3) 2 direct product SU(3) 3 gauge theory, where quarks of the ith generation transform as triplets under SU(3)/sub i/ and singlets under the other two factors. The usual color group is then identified with the diagonal subgroup, which remains exact after symmetry breaking. The gauge bosons associated with the 16 broken generators then form two massive octets under ordinary color. The interactions between quarks and these heavy gluonlike particles are explicitly nonuniversal and thus an exploration of their physical implications allows us to shed light on the fundamental issue of strong-interaction universality. Nonuniversality and weak flavor mixing are shown to generate heavy-gluon-induced flavor-changing neutral currents. The phenomenology of these processes is studied, as they provide the major experimental constraint on the extended theory. Three symmetry-breaking scenarios are presented. The first has color breaking occurring at the weak scale, while the second and third divorce the two scales. The third model has the interesting feature of radiatively induced off-diagonal Kobayashi-Maskawa matrix elements

  5. Retinal pigment epithelium findings in patients with albinism using wide-field polarization-sensitive optical coherence tomography.

    Science.gov (United States)

    Schütze, Christopher; Ritter, Markus; Blum, Robert; Zotter, Stefan; Baumann, Bernhard; Pircher, Michael; Hitzenberger, Christoph K; Schmidt-Erfurth, Ursula

    2014-11-01

    To investigate pigmentation characteristics of the retinal pigment epithelium (RPE) in patients with albinism using wide-field polarization-sensitive optical coherence tomography compared with intensity-based spectral domain optical coherence tomography and fundus autofluorescence imaging. Five patients (10 eyes) with previously genetically diagnosed albinism and 5 healthy control subjects (10 eyes) were imaged by a wide-field polarization-sensitive optical coherence tomography system (scan angle: 40 × 40° on the retina), sensitive to melanin contained in the RPE, based on the polarization state of backscattered light. Conventional intensity-based spectral domain optical coherence tomography and fundus autofluorescence examinations were performed. Retinal pigment epithelium-pigmentation was analyzed qualitatively and quantitatively based on depolarization assessed by polarization-sensitive optical coherence tomography. This study revealed strong evidence of polarization-sensitive optical coherence tomography to specifically image melanin in the RPE. Depolarization of light backscattered by the RPE in patients with albinism was reduced compared with normal subjects. Heterogeneous RPE-specific depolarization characteristics were observed in patients with albinism. Reduction of depolarization observed in the light backscattered by the RPE in patients with albinism corresponds to expected decrease of RPE pigmentation. The degree of depigmentation of the RPE is possibly associated with visual acuity. Findings suggest that different albinism genotypes result in heterogeneous levels of RPE pigmentation. Polarization-sensitive optical coherence tomography showed a heterogeneous appearance of RPE pigmentation in patients with albinism depending on different genotypes.

  6. Atoms in strong laser fields

    International Nuclear Information System (INIS)

    L'Huillier, A.

    2002-01-01

    When a high-power laser focuses into a gas of atoms, the electromagnetic field becomes of the same magnitude as the Coulomb field which binds a 1s electron in a hydrogen atom. 3 highly non-linear phenomena can happen: 1) ATI (above threshold ionization): electrons initially in the ground state absorb a large number of photons, many more than the minimum number required for ionization; 2) multiple ionization: many electrons can be emitted one at a time, in a sequential process, or simultaneously in a mechanism called direct or non-sequential; and 3) high order harmonic generation (HHG): efficient photon emission in the extreme ultraviolet range, in the form of high-order harmonics of the fundamental laser field can occur. The theoretical problem consists in solving the time dependent Schroedinger equation (TDSE) that describes the interaction of a many-electron atom with a laser field. A number of methods have been proposed to solve this problem in the case of a hydrogen atom or a single-active electron atom in a strong laser field. A large effort is presently being devoted to go beyond the single-active approximation. The understanding of the physics of the interaction between atoms and strong laser fields has been provided by a very simple model called ''simple man's theory''. A unified view of HHG, ATI, and non-sequential ionization, originating from the simple man's model and the strong field approximation, expressed in terms of electrons trajectories or quantum paths is slowly emerging. (A.C.)

  7. Beam broadening of polar molecules and clusters in deflection experiments.

    Science.gov (United States)

    Bulthuis, J; Kresin, V V

    2012-01-07

    A beam of rotating dipolar particles (molecules or clusters) will broaden when passed through an electric or magnetic field gradient region. This broadening, which is a common experimental observable, can be expressed in terms of the variance of the distribution of the resulting polarization orientation (the direction cosine). Here, the broadening for symmetric-top and linear rotors is discussed. These two types of rotors have qualitatively different low-field orientation distribution functions, but behave similarly in a strong field. While analytical expressions for the polarization variance can be derived from first-order perturbation theory, for experimental guidance it is important to identify the applicability and limitations of these expressions, and the general dependence of the broadening on the experimental parameters. For this purpose, the analytical results are compared with the full diagonalization of the rotational Stark-effect matrices. Conveniently for experimental estimations, it is found that for symmetric tops, the dependence of the broadening parameter on the rotational constant, the axial ratio, and the field strength remains similar to the analytical expression even outside of the perturbative regime. Also, it is observed that the shape envelope, the centroid, and the width of the orientation distribution function for a symmetric top are quite insensitive to the value of its rotational constant (except at low rotational temperatures).

  8. Our Polar Past

    Science.gov (United States)

    Clary, Renee; Wandersee, James

    2009-01-01

    The study of polar exploration is fascinating and offers students insights into the history, culture, and politics that affect the developing sciences at the farthest ends of Earth. Therefore, the authors think there is value in incorporating polar exploration accounts within modern science classrooms, and so they conducted research to test their…

  9. Terahertz polarization imaging

    NARCIS (Netherlands)

    Van der Valk, N.C.J.; Van der Marel, W.A.M.; Planken, P.C.M.

    2005-01-01

    We present a new method to measure the polarization state of a terahertz pulse by using a modified electrooptic sampling setup. To illustrate the power of this method, we show two examples in which the knowledge of the polarization of the terahertz pulse is essential for interpreting the results:

  10. Polarized proton beams

    International Nuclear Information System (INIS)

    Roser, T.

    1995-01-01

    The acceleration of polarized proton beams in circular accelerators is complicated by the presence of numerous depolarizing spin resonances. Careful and tedious minimization of polarization loss at each of these resonances allowed acceleration of polarized proton beams up to 22 GeV. It has been the hope that Siberian Snakes, which are local spin rotators inserted into ring accelerators, would eliminate these resonances and allow acceleration of polarized beams with the same ease and efficiency that is now routine for unpolarized beams. First tests at IUCF with a full Siberian Snake showed that the spin dynamics with a Snake can be understood in detail. The author now has results of the first tests of a partial Siberian Snake at the AGS, accelerating polarized protons to an energy of about 25 GeV. These successful tests of storage and acceleration of polarized proton beams open up new possibilities such as stored polarized beams for internal target experiments and high energy polarized proton colliders

  11. Polar Science Is Cool!

    Science.gov (United States)

    Weeks, Sophie

    2012-01-01

    Children are fascinated by the fact that polar scientists do research in extremely cold and dangerous places. In the Arctic they might be viewed as lunch by a polar bear. In the Antarctic, they could lose toes and fingers to frostbite and the wind is so fast it can rip skin off. They camp on ice in continuous daylight, weeks from any form of…

  12. Optically polarized 3He

    Science.gov (United States)

    Gentile, T. R.; Nacher, P. J.; Saam, B.; Walker, T. G.

    2018-01-01

    This article reviews the physics and technology of producing large quantities of highly spin-polarized 3He nuclei using spin-exchange (SEOP) and metastability-exchange (MEOP) optical pumping. Both technical developments and deeper understanding of the physical processes involved have led to substantial improvements in the capabilities of both methods. For SEOP, the use of spectrally narrowed lasers and K-Rb mixtures has substantially increased the achievable polarization and polarizing rate. For MEOP nearly lossless compression allows for rapid production of polarized 3He and operation in high magnetic fields has likewise significantly increased the pressure at which this method can be performed, and revealed new phenomena. Both methods have benefitted from development of storage methods that allow for spin-relaxation times of hundreds of hours, and specialized precision methods for polarimetry. SEOP and MEOP are now widely applied for spin-polarized targets, neutron spin filters, magnetic resonance imaging, and precision measurements. PMID:29503479

  13. Optically polarized 3He

    Science.gov (United States)

    Gentile, T. R.; Nacher, P. J.; Saam, B.; Walker, T. G.

    2017-10-01

    This article reviews the physics and technology of producing large quantities of highly spin-polarized 3He nuclei using spin-exchange (SEOP) and metastability-exchange (MEOP) optical pumping. Both technical developments and deeper understanding of the physical processes involved have led to substantial improvements in the capabilities of both methods. For SEOP, the use of spectrally narrowed lasers and K-Rb mixtures has substantially increased the achievable polarization and polarizing rate. For MEOP nearly lossless compression allows for rapid production of polarized 3He and operation in high magnetic fields has likewise significantly increased the pressure at which this method can be performed, and revealed new phenomena. Both methods have benefitted from development of storage methods that allow for spin-relaxation times of hundreds of hours, and specialized precision methods for polarimetry. SEOP and MEOP are now widely applied for spin-polarized targets, neutron spin filters, magnetic resonance imaging, and precision measurements.

  14. Parallel Polarization State Generation.

    Science.gov (United States)

    She, Alan; Capasso, Federico

    2016-05-17

    The control of polarization, an essential property of light, is of wide scientific and technological interest. The general problem of generating arbitrary time-varying states of polarization (SOP) has always been mathematically formulated by a series of linear transformations, i.e. a product of matrices, imposing a serial architecture. Here we show a parallel architecture described by a sum of matrices. The theory is experimentally demonstrated by modulating spatially-separated polarization components of a laser using a digital micromirror device that are subsequently beam combined. This method greatly expands the parameter space for engineering devices that control polarization. Consequently, performance characteristics, such as speed, stability, and spectral range, are entirely dictated by the technologies of optical intensity modulation, including absorption, reflection, emission, and scattering. This opens up important prospects for polarization state generation (PSG) with unique performance characteristics with applications in spectroscopic ellipsometry, spectropolarimetry, communications, imaging, and security.

  15. Stability of superfluid phases in the 2D spin-polarized attractive Hubbard model

    Science.gov (United States)

    Kujawa-Cichy, A.; Micnas, R.

    2011-08-01

    We study the evolution from the weak coupling (BCS-like limit) to the strong coupling limit of tightly bound local pairs (LPs) with increasing attraction, in the presence of the Zeeman magnetic field (h) for d=2, within the spin-polarized attractive Hubbard model. The broken symmetry Hartree approximation as well as the strong coupling expansion are used. We also apply the Kosterlitz-Thouless (KT) scenario to determine the phase coherence temperatures. For spin-independent hopping integrals (t↑=t↓), we find no stable homogeneous polarized superfluid (SCM) state in the ground state for the strong attraction and obtain that for a two-component Fermi system on a 2D lattice with population imbalance, phase separation (PS) is favoured for a fixed particle concentration, even on the LP (BEC) side. We also examine the influence of spin-dependent hopping integrals (mass imbalance) on the stability of the SCM phase. We find a topological quantum phase transition (Lifshitz type) from the unpolarized superfluid phase (SC0) to SCM and tricritical points in the h-|U| and t↑/t↓-|U| ground-state phase diagrams. We also construct the finite temperature phase diagrams for both t↑=t↓ and t↑≠t↓ and analyze the possibility of occurrence of a spin-polarized KT superfluid.

  16. Polarized targets in high energy physics

    Energy Technology Data Exchange (ETDEWEB)

    Cates, G.D. Jr. [Princeton Univ., NJ (United States)

    1994-12-01

    Various approaches are discussed for producing polarized nuclear targets for high energy physics experiments. As a unifying theme, examples are drawn from experiments to measure spin dependent structure functions of nucleons in deep inelastic scattering. This single physics goal has, over roughly two decades, been a driving force in advances in target technology. Actual or planned approaches have included solid targets polarized by dynamic nuclear polarization (DNP), several types of internal targets for use in storage rings, and gaseous {sup 3}He targets polarized by spin-exchange optical pumping. This last approach is the type of target adopted for SLAC E-142, an experiment to measure the spin structure function of the neutron, and is described in detail.

  17. Channel-closing effects in strong-field ionization by a bicircular field

    Science.gov (United States)

    Milošević, D. B.; Becker, W.

    2018-03-01

    Channel-closing effects, such as threshold anomalies and resonantlike intensity-dependent enhancements in strong-field ionization by a bicircular laser field are analyzed. A bicircular field consists of two coplanar corotating or counter-rotating circularly polarized fields having different frequencies. For the total detachment rate of a negative ion by a bicircular field we observe threshold anomalies and explain them using the Wigner threshold law and energy and angular momentum conservation. For the corotating bicircular case, these effects are negligible, while for the counter-rotating case they are pronounced and their position depends on the magnetic quantum number of the initial state. For high-order above-threshold ionization of rare-gas atoms by a counter-rotating bicircular laser field we observe very pronounced intensity-dependent enhancements. We find all four types of threshold anomalies known from collision theory. Contrary to the case of linear polarization, channel-closing effects for a bicircular field are visible also in the cutoff region of the electron energy spectrum, which is explained using quantum-orbit theory.

  18. Ion Concentration Polarization by Bifurcated Current Path.

    Science.gov (United States)

    Kim, Junsuk; Cho, Inhee; Lee, Hyomin; Kim, Sung Jae

    2017-07-11

    Ion concentration polarization (ICP) is a fundamental electrokinetic process that occurs near a perm-selective membrane under dc bias. Overall process highly depends on the current transportation mechanisms such as electro-convection, surface conduction and diffusioosmosis and the fundamental characteristics can be significantly altered by external parameters, once the permselectivity was fixed. In this work, a new ICP device with a bifurcated current path as for the enhancement of the surface conduction was fabricated using a polymeric nanoporous material. It was protruded to the middle of a microchannel, while the material was exactly aligned at the interface between two microchannels in a conventional ICP device. Rigorous experiments revealed out that the propagation of ICP layer was initiated from the different locations of the protruded membrane according to the dominant current path which was determined by a bulk electrolyte concentration. Since the enhancement of surface conduction maintained the stability of ICP process, a strong electrokinetic flow associated with the amplified electric field inside ICP layer was significantly suppressed over the protruded membrane even at condensed limit. As a practical example of utilizing the protruded device, we successfully demonstrated a non-destructive micro/nanofluidic preconcentrator of fragile cellular species (i.e. red blood cells).

  19. The lambda sigma calculus and strong normalization

    DEFF Research Database (Denmark)

    Schack-Nielsen, Anders; Schürmann, Carsten

    Explicit substitution calculi can be classified into several dis- tinct categories depending on whether they are confluent, meta-confluent, strong normalization preserving, strongly normalizing, simulating, fully compositional, and/or local. In this paper we present a variant of the λσ-calculus......, which satisfies all seven conditions. In particular, we show how to circumvent Mellies counter-example to strong normalization by a slight restriction of the congruence rules. The calculus is implemented as the core data structure of the Celf logical framework. All meta-theoretic aspects of this work...

  20. [Cell polarity in the cardiovascular system].

    Science.gov (United States)

    Haller, C; Kübler, W

    1999-05-01

    The importance of cell polarity as a fundamental biological principle is increasingly recognized in the cardiovascular system. Polar cell mechanisms underlie not only the development of the heart and blood vessels, but also play a major role in the adult organism for polarized endothelial functions such as the separation of the intra- and extravascular compartment and the vectorial exchange of substances between these compartments. Endothelial cells are connected through intercellular junctions which separate the functionally and structurally distinct luminal and abluminal cell surfaces. The luminal plasma membrane is in contact with the blood and takes part in the regulation of hemostasis. The abluminal cell membrane connects the endothelial cell with the basement membrane and modulates blood flow through the release of vasoactive substances. Results from epithelial model systems have shown that the polarized cell phenotype is generated by specific protein sorting and regulated protein trafficking between the trans-Golgi network and the cell surface. The polarized distribution of cell membrane proteins is maintained by anchorage with the cytoskeleton and limitation of lateral diffusion by tight junctions. Disturbances of cell polarity may contribute to the pathogenesis of disease states, including ischemic and radiocontrast-induced acute renal failure and carcinomas. Recent results have demonstrated the importance of cholesterol for protein traffic from the trans-Golgi network to the apical cell membrane. This novel intracellular function of cholesterol could point to a connection between cell polarity and the pathogenesis of arteriosclerosis. The polarity of the endothelium also has to be taken into account when developing gene-therapeutic strategies, since therapeutic success will not only depend on the efficient expression of the desired gene product, but also on its correct cellular location or secretion into the correct extracellular compartment. These