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Sample records for anderson localization excited

  1. Quantum walk and Anderson localization of rotational excitations in disordered ensembles of polar molecules

    E-print Network

    Tianrui Xu; Roman V. Krems

    2015-05-05

    We consider the dynamics of rotational excitations placed on a single molecule in spatially disordered 1D, 2D and 3D ensembles of ultracold molecules trapped in optical lattices. The disorder arises from incomplete populations of optical lattices with molecules. This leads to a model corresponding to a quantum particle with long-range tunnelling amplitudes moving on a lattice with the same on-site energy but with forbidden access to random sites (vacancies). We examine the time and length scales of Anderson localization for this type of disorder with realistic experimental parameters in the Hamiltonian. We show that for an experimentally realized system of KRb molecules on an optical lattice this type of disorder leads to disorder-induced localization in 1D and 2D systems on a time scale $t \\sim 1$ sec. For 3D lattices with $55$ sites in each dimension and vacancy concentration $ 90~\\%$, the rotational excitations diffuse to the edges of the lattice and show no signature of Anderson localization. We examine the role of the long-range tunnelling amplitudes allowing for transfer of rotational excitations between distant lattice sites. Our results show that the long-range tunnelling has little impact on the dynamics in the diffusive regime but affects significantly the localization dynamics in lattices with large concentrations of vacancies, enhancing the width of the localized distributions in 2D lattices by more than a factor of 2. Our results raise a general question whether quantum particles with long-range tunnelling can undergo quantum localization in 3D lattices with substitutional disorder.

  2. Anderson localization in laser-kicked molecules

    NASA Astrophysics Data System (ADS)

    Floß, Johannes; Fishman, Shmuel; Averbukh, Ilya Sh.

    2013-08-01

    The paper explores the prospects of observing the phenomenon of dynamical Anderson localization via nonresonant Raman-type rotational excitation of molecules by periodic trains of short laser pulses. We define conditions for such an experiment and show that current femtosecond technology used for nonadiabatic laser alignment of linear molecules is sufficient for this task. Several observables which can serve as indicators for Anderson localization are suggested for measurement, and the influence of experimental limitations imposed by the laser intensity noise, finite pulse duration, limited number of pulses in a train, and thermal effects is analyzed.

  3. Hybrid Bloch-Anderson localization of light

    E-print Network

    Stutzer, Simon; Vysloukh, Victor A; Konotop, Vladimir V; Nolte, Stefan; Torner, Lluis; Szameit, Alexander

    2013-01-01

    We investigate the interplay of Bloch oscillations and Anderson localization in optics. Gradual washing out of Bloch oscillations and the formation of nearly stationary averaged intensity distributions, which are symmetric for narrow and strongly asymmetric for broad input excitations, are observed experimentally in laser-written waveguide arrays. At large disorder levels Bloch oscillations are completely destroyed and both narrow and wide excitations lead to symmetric stationary averaged intensity distributions with exponentially decaying tails.

  4. Anderson localization of light near boundaries of disordered photonic lattices

    SciTech Connect

    Jovic, Dragana M.; Kivshar, Yuri S.; Denz, Cornelia; Belic, Milivoj R.

    2011-03-15

    We study numerically the effect of boundaries on Anderson localization of light in truncated two-dimensional photonic lattices in a nonlinear medium. We demonstrate suppression of Anderson localization at the edges and corners, so that stronger disorder is needed near the boundaries to obtain the same localization as in the bulk. We find that the level of suppression depends on the location in the lattice (edge vs corner), as well as on the strength of disorder. We also discuss the effect of nonlinearity on various regimes of Anderson localization.

  5. Anderson localization effects near the Mott metal-insulator transition

    NASA Astrophysics Data System (ADS)

    Bragança, Helena; Aguiar, M. C. O.; Vu?i?evi?, J.; Tanaskovi?, D.; Dobrosavljevi?, V.

    2015-09-01

    The interplay between Mott and Anderson routes to localization in disordered interacting systems gives rise to different transitions and transport regimes. Here, we investigate the phase diagram at finite temperatures using dynamical mean-field theory combined with typical medium theory, which is an effective theory of the Mott-Anderson metal-insulator transition. We mainly focus on the properties of the coexistence region associated with the Mott phase transition. For weak disorder, the coexistence region is found to be similar to that in the clean case. However, as we increase disorder, Anderson localization effects are responsible for shrinking the coexistence region, and at sufficiently strong disorder (approximately equal to twice the bare bandwidth) it drastically narrows, the critical temperature Tc abruptly goes to zero, and we observe a phase transition in the absence of a coexistence of the metallic and insulating phases. In this regime, the effects of interaction and disorder are found to be of comparable importance for charge localization.

  6. Ergodicity and dynamical localization for Delone-Anderson operators

    NASA Astrophysics Data System (ADS)

    Germinet, François; Müller, Peter; Rojas-Molina, Constanza

    2015-11-01

    We study the ergodic properties of Delone-Anderson operators, using the framework of randomly colored Delone sets and Delone dynamical systems. In particular, we show the existence of the integrated density of states and, under some assumptions on the geometric complexity of the underlying Delone sets, we obtain information on the almost-sure spectrum of the family of random operators. We then exploit these results to study the Lifshitz-tail behavior of the integrated density of states of a Delone-Anderson operator at the bottom of the spectrum. Furthermore, we use Lifshitz-tail estimates as an input for the multi-scale analysis to prove dynamical localization.

  7. Anderson localization of light in disordered superlattices containing graphene layers

    NASA Astrophysics Data System (ADS)

    Chaves, A. J.; Peres, N. M. R.; Pinheiro, F. A.

    2015-11-01

    We perform a theoretical investigation of light propagation and Anderson localization in one-dimensional disordered superlattices composed of dielectric stacks with graphene sheets in between. Disorder is introduced either on graphene material parameters (e.g., Fermi energy) or on the widths of the dielectric stacks. We derive an analytic expression for the localization length ? , and we compare it to numerical simulations using the transfer-matrix technique; a very good agreement is found. We demonstrate that the presence of graphene may strongly attenuate the anomalously delocalized Brewster modes, and it is at the origin of a periodic dependence of ? on frequency, in contrast to the usual asymptotic decay, ? ??-2 . By unveiling the effects of graphene on Anderson localization of light, we pave the way for new applications of graphene-based, disordered photonic devices in the THz spectral range.

  8. Centrifugal Distortion Causes Anderson Localization in Laser Kicked Molecules

    NASA Astrophysics Data System (ADS)

    Floss, Johannes; Averbukh, Ilya Sh.

    2014-05-01

    The periodically kicked 2D rotor is a textbook model in nonlinear dynamics. The classical kicked rotor can exhibit truly chaotic motion, whilst in the quantum regime this chaotic motion is suppressed by a mechanism similar to Anderson Localization. Up to now, these effects have been mainly observed in an atom optics analogue of a quantum rotor: cold atoms in a standing light wave. We demonstrate that common linear molecules (like N2, O2, CO2, ...), kicked by a train of short linearly polarized laser pulses, can exhibit a new mechanism for dynamical Anderson Localization due to their non-rigidity. When the pulses are separated by the rotational revival time trev = ?? / B , the angular momentum J grows ballistically (Quantum Resonance). We show that, due to the centrifugal distortion of fast spinning molecules, above some critical value J =Jcr the Quantum Resonance is suppressed via the mechanism of Anderson Localization. This leads to a non-sinusoidal oscillation of the angular momentum distribution, which may be experimentally observed even at ambient conditions by using current techniques for laser molecular alignment.

  9. Anderson localization on the Bethe lattice: nonergodicity of extended States.

    PubMed

    De Luca, A; Altshuler, B L; Kravtsov, V E; Scardicchio, A

    2014-07-25

    Statistical analysis of the eigenfunctions of the Anderson tight-binding model with on-site disorder on regular random graphs strongly suggests that the extended states are multifractal at any finite disorder. The spectrum of fractal dimensions f(?) defined in Eq. (3) remains positive for ? noticeably far from 1 even when the disorder is several times weaker than the one which leads to the Anderson localization; i.e., the ergodicity can be reached only in the absence of disorder. The one-particle multifractality on the Bethe lattice signals on a possible inapplicability of the equipartition law to a generic many-body quantum system as long as it remains isolated. PMID:25105646

  10. Experimental Observation of Two-Dimensional Anderson Localization with the Atomic Kicked Rotor.

    PubMed

    Manai, Isam; Clément, Jean-François; Chicireanu, Radu; Hainaut, Clément; Garreau, Jean Claude; Szriftgiser, Pascal; Delande, Dominique

    2015-12-11

    Dimension 2 is expected to be the lower critical dimension for Anderson localization in a time-reversal-invariant disordered quantum system. Using an atomic quasiperiodic kicked rotor-equivalent to a two-dimensional Anderson-like model-we experimentally study Anderson localization in dimension 2 and we observe localized wave function dynamics. We also show that the localization length depends exponentially on the disorder strength and anisotropy and is in quantitative agreement with the predictions of the self-consistent theory for the 2D Anderson localization. PMID:26705619

  11. Fractional moment methods for Anderson localization with SAW representation

    NASA Astrophysics Data System (ADS)

    Suzuki, Fumika

    2013-03-01

    The Green function contains much information about physical systems. Mathematically, the fractional moment method (FMM) developed by Aizenman and Molchanov connects the Green function and the transport of electrons in the Anderson model. Recently, it has been discovered that the Green function on a graph can be represented using self-avoiding walks on a graph, which allows us to connect localization properties in the system and graph properties. We discuss FMM in terms of the self-avoiding walks on a general graph, the only general condition being that the graph has a uniform bound on the vertex degree.

  12. Anderson localization and Mott insulator phase in the time domain

    PubMed Central

    Sacha, Krzysztof

    2015-01-01

    Particles in space periodic potentials constitute standard models for investigation of crystalline phenomena in solid state physics. Time periodicity of periodically driven systems is a close analogue of space periodicity of solid state crystals. There is an intriguing question if solid state phenomena can be observed in the time domain. Here we show that wave-packets localized on resonant classical trajectories of periodically driven systems are ideal elements to realize Anderson localization or Mott insulator phase in the time domain. Uniform superpositions of the wave-packets form stationary states of a periodically driven particle. However, an additional perturbation that fluctuates in time results in disorder in time and Anderson localization effects emerge. Switching to many-particle systems we observe that depending on how strong particle interactions are, stationary states can be Bose-Einstein condensates or single Fock states where definite numbers of particles occupy the periodically evolving wave-packets. Our study shows that non-trivial crystal-like phenomena can be observed in the time domain. PMID:26074169

  13. Anderson localization and Mott insulator phase in the time domain

    E-print Network

    Krzysztof Sacha

    2015-06-16

    Particles in space periodic potentials constitute standard models for investigation of crystalline phenomena in solid state physics. Time periodicity of periodically driven systems is a close analogue of space periodicity of solid state crystals. There is an intriguing question if solid state phenomena can be observed in the time domain. Here we show that wave-packets localized on resonant classical trajectories of periodically driven systems are ideal elements to realize Anderson localization or Mott insulator phase in the time domain. Uniform superpositions of the wave-packets form stationary states of a periodically driven particle. However, an additional perturbation that fluctuates in time results in disorder in time and Anderson localization effects emerge. Switching to many-particle systems we observe that depending on how strong particle interactions are, stationary states can be Bose-Einstein condensates or single Fock states where definite numbers of particles occupy the periodically evolving wave-packets. Our study shows that non-trivial crystal-like phenomena can be observed in the time domain.

  14. Anderson Localization, Non-linearity and Stable Genetic Diversity

    E-print Network

    Epstein, Charles L

    2009-01-01

    In many models of genotypic evolution, the vector of genotype populations satisfies a system of linear ordinary differential equations. This system of equations models a competition between differential replication rates (fitness) and mutation. Mutation operates as a generalized diffusion process on genotype space. In the large time asymptotics, the replication term tends to produce a single dominant quasispecies, unless the mutation rate is too high, in which case the populations of different genotypes becomes de-localized. We introduce a more macroscopic picture of genotypic evolution wherein a random replication term in the linear model displays features analogous to Anderson localization. When coupled with non-linearities that limit the population of any given genotype, we obtain a model whose large time asymptotics display stable genotypic diversity

  15. Quantum resonance, Anderson localization, and selective manipulations in molecular mixtures by ultrashort laser pulses

    NASA Astrophysics Data System (ADS)

    Floß, Johannes; Averbukh, Ilya Sh.

    2012-08-01

    We show that the current laser technology used for field-free molecular alignment via impulsive Raman rotational excitation allows for observing long-discussed nonlinear quantum phenomena in the dynamics of the periodically kicked rotor. This includes the scaling of the absorbed energy near the conditions of quantum resonance and Anderson-like localization in the angular momentum. Based on this, we show that periodic trains of short laser pulses provide an efficient tool for selective rotational excitation and alignment in a molecular mixture. We demonstrate the efficiency of this approach by applying it to a mixture of two nitrogen isotopologues (14N2 and 15N2), and show that strong selectivity is possible even at room temperature.

  16. Anderson localization of matter waves in quantum-chaos theory

    NASA Astrophysics Data System (ADS)

    Fratini, E.; Pilati, S.

    2015-06-01

    We study the Anderson localization of atomic gases exposed to three-dimensional optical speckles by analyzing the statistics of the energy-level spacings. This method allows us to consider realistic models of the speckle patterns, taking into account the strongly anisotropic correlations which are realized in concrete experimental configurations. We first compute the mobility edge Ec of a speckle pattern created using a single laser beam. We find that Ec drifts when we vary the anisotropy of the speckle grains, going from higher values when the speckles are squeezed along the beam propagation axis to lower values when they are elongated. We also consider the case where two speckle patterns are superimposed, forming interference fringes, and we find that Ec is increased compared to the case of idealized isotropic disorder. We discuss the important implications of our findings for cold-atom experiments.

  17. Anomalously suppressed localization in the two-channel Anderson model.

    PubMed

    Nguyen, Ba Phi; Kim, Kihong

    2012-04-01

    We study numerically the localization properties of a two-channel quasi-one-dimensional Anderson model with uncorrelated diagonal disorder within the nearest-neighbor tight-binding approximation. We calculate and analyze the disorder-averaged transmittance and the Lyapunov exponent. We find that the localization of the entire system is enhanced by increasing the interchain hopping strength t?. From the numerical investigation of the energy dependence of the Lyapunov exponent for many different interchain hopping strengths, we find that apart from the band center anomaly, which usually occurs in strictly one-dimensional disordered systems, additional anomalies appear at special spectral points. They are found to be associated with the interchain hopping strength and occur at E = ± t?/2 and ± t?. We find that the anomalies at E = ± t? are associated with the ?-coupling occurring within one energy band and those at E = ± t?/2 are associated with the ?-coupling occurring between two different energy bands. Despite having a similar origin, these two anomalies have distinct characteristics in their dependence on the strength of disorder. We also show that for a suitable range of parameter values, effectively delocalized states are observed in finite-size systems. PMID:22406739

  18. Anderson Localization for Schrödinger Operators on with Strongly Mixing Potentials

    NASA Astrophysics Data System (ADS)

    Bourgain, Jean; Schlag, Wilhelm

    In this paper we show that for a.e. x?[ 0,2 ?) the operators defined on as and with Dirichlet condition ?- 1= 0, have pure point spectrum in with exponentially decaying eigenfunctions where ? > 0 and are small. As it is a simple consequence of known techniques that for small ? one has [- 2 +?, 2-?]? spectrum (H(x)) for a.e.x?[ 0, 2 ?), we thus established Anderson localization on the spectrum up to the edges and the center. More general potentials than cosine can be treated, but only those energies with nonzero spectral density are allowed. Finally, we prove the same result for operators on the whole line with potential , where A:?2-->?2 is a hyperbolic toral automorphism, F?C1(?2), ?F= 0, and ? small. The basis for our analysis is an asymptotic formula for the Lyapunov exponent for ?--> 0 by Figotin-Pastur, and generalized by Chulaevski-Spencer. We combine this asymptotic expansion with certain martingale large deviation estimates in order to apply the methods developed by Bourgain and Goldstein in the quasi-periodic case.

  19. Anderson attractors in active arrays

    PubMed Central

    Laptyeva, Tetyana V.; Tikhomirov, Andrey A.; Kanakov, Oleg I.; Ivanchenko, Mikhail V.

    2015-01-01

    In dissipationless linear media, spatial disorder induces Anderson localization of matter, light, and sound waves. The addition of nonlinearity causes interaction between the eigenmodes, which results in a slow wave diffusion. We go beyond the dissipationless limit of Anderson arrays and consider nonlinear disordered systems that are subjected to the dissipative losses and energy pumping. We show that the Anderson modes of the disordered Ginsburg-Landau lattice possess specific excitation thresholds with respect to the pumping strength. When pumping is increased above the threshold for the band-edge modes, the lattice dynamics yields an attractor in the form of a stable multi-peak pattern. The Anderson attractor is the result of a joint action by the pumping-induced mode excitation, nonlinearity-induced mode interactions, and dissipative stabilization. The regimes of Anderson attractors can be potentially realized with polariton condensates lattices, active waveguide or cavity-QED arrays. PMID:26304462

  20. Anderson attractors in active arrays

    NASA Astrophysics Data System (ADS)

    Laptyeva, Tetyana V.; Tikhomirov, Andrey A.; Kanakov, Oleg I.; Ivanchenko, Mikhail V.

    2015-08-01

    In dissipationless linear media, spatial disorder induces Anderson localization of matter, light, and sound waves. The addition of nonlinearity causes interaction between the eigenmodes, which results in a slow wave diffusion. We go beyond the dissipationless limit of Anderson arrays and consider nonlinear disordered systems that are subjected to the dissipative losses and energy pumping. We show that the Anderson modes of the disordered Ginsburg-Landau lattice possess specific excitation thresholds with respect to the pumping strength. When pumping is increased above the threshold for the band-edge modes, the lattice dynamics yields an attractor in the form of a stable multi-peak pattern. The Anderson attractor is the result of a joint action by the pumping-induced mode excitation, nonlinearity-induced mode interactions, and dissipative stabilization. The regimes of Anderson attractors can be potentially realized with polariton condensates lattices, active waveguide or cavity-QED arrays.

  1. Anderson attractors in active arrays.

    PubMed

    Laptyeva, Tetyana V; Tikhomirov, Andrey A; Kanakov, Oleg I; Ivanchenko, Mikhail V

    2015-01-01

    In dissipationless linear media, spatial disorder induces Anderson localization of matter, light, and sound waves. The addition of nonlinearity causes interaction between the eigenmodes, which results in a slow wave diffusion. We go beyond the dissipationless limit of Anderson arrays and consider nonlinear disordered systems that are subjected to the dissipative losses and energy pumping. We show that the Anderson modes of the disordered Ginsburg-Landau lattice possess specific excitation thresholds with respect to the pumping strength. When pumping is increased above the threshold for the band-edge modes, the lattice dynamics yields an attractor in the form of a stable multi-peak pattern. The Anderson attractor is the result of a joint action by the pumping-induced mode excitation, nonlinearity-induced mode interactions, and dissipative stabilization. The regimes of Anderson attractors can be potentially realized with polariton condensates lattices, active waveguide or cavity-QED arrays. PMID:26304462

  2. Anderson attractors in active arrays

    E-print Network

    T. V. Laptyeva; A. A. Tikhomirov; O. I. Kanakov; M. V. Ivanchenko

    2015-06-28

    In dissipationless linear media, spatial disorder induces Anderson localization of matter, light, and sound waves. The addition of nonlinearity causes interaction between the eigenmodes, which results in a slow wave diffusion. We go beyond the dissipationless limit of Anderson arrays and consider nonlinear disordered systems that are subjected to the dissipative losses and energy pumping. We show that the Anderson modes of the disordered Ginsburg-Landau lattice possess specific excitation thresholds with respect to the pumping strength. When pumping is increased above the threshold for the band-edge modes, the lattice dynamics yields an attractor in the form of a stable multi-peak pattern. The Anderson attractor is the result of a joint action by the pumping-induced mode excitation, nonlinearity-induced mode interactions, and dissipative stabilization. The regimes of Anderson attractors can be potentially realized with polariton condensates lattices, active waveguide or cavity-QED arrays.

  3. Absence of transport in Anderson localization Fumihiko Nakano

    E-print Network

    that it is zero almost surely. This result has wider applicability than our previous work[12], while­diagonal compo­ nent of the conductivity tensor which recovers the famous result of quantization of Hall conductivity in quantum Hall systems. 1 Introduction Since the pioneering work of Anderson[5], where he

  4. Wireless Sensor Network Localization Techniques Guoqiang Mao, Baris Fidan and Brian D.O. Anderson

    E-print Network

    Scheuermann, Peter

    1 Wireless Sensor Network Localization Techniques Guoqiang Mao, Baris¸ Fidan and Brian D.O. Anderson Abstract-- Wireless sensor network localization is an important area that attracted significant on possible approaches to them. Index Terms-- wireless sensor networks, localization, AOA, RSS, TDOA. I

  5. Transverse Anderson localization of light near Dirac points of photonic nanostructures.

    PubMed

    Deng, Hanying; Chen, Xianfeng; Malomed, Boris A; Panoiu, Nicolae C; Ye, Fangwei

    2015-01-01

    We perform a comparative study of the Anderson localization of light beams in disordered layered photonic nanostructures that, in the limit of periodic layer distribution, possess either a Dirac point or a Bragg gap in the spectrum of the wavevectors. In particular, we demonstrate that the localization length of the Anderson modes increases when the width of the Bragg gap decreases, such that in the vanishingly small bandgap limit, namely when a Dirac point is formed, even extremely high levels of disorder are unable to localize the optical modes residing near the Dirac point. A comparative analysis of the key features of the propagation of Anderson modes formed in the Bragg gap or near the Dirac point is also presented. Our findings could provide valuable guidelines in assessing the influence of structural disorder on the functionality of a broad array of optical nanodevices. PMID:26498634

  6. Transverse Anderson localization of light near Dirac points of photonic nanostructures

    NASA Astrophysics Data System (ADS)

    Deng, Hanying; Chen, Xianfeng; Malomed, Boris A.; Panoiu, Nicolae C.; Ye, Fangwei

    2015-10-01

    We perform a comparative study of the Anderson localization of light beams in disordered layered photonic nanostructures that, in the limit of periodic layer distribution, possess either a Dirac point or a Bragg gap in the spectrum of the wavevectors. In particular, we demonstrate that the localization length of the Anderson modes increases when the width of the Bragg gap decreases, such that in the vanishingly small bandgap limit, namely when a Dirac point is formed, even extremely high levels of disorder are unable to localize the optical modes residing near the Dirac point. A comparative analysis of the key features of the propagation of Anderson modes formed in the Bragg gap or near the Dirac point is also presented. Our findings could provide valuable guidelines in assessing the influence of structural disorder on the functionality of a broad array of optical nanodevices.

  7. Transverse Anderson localization of light near Dirac points of photonic nanostructures

    PubMed Central

    Deng, Hanying; Chen, Xianfeng; Malomed, Boris A.; Panoiu, Nicolae C.; Ye, Fangwei

    2015-01-01

    We perform a comparative study of the Anderson localization of light beams in disordered layered photonic nanostructures that, in the limit of periodic layer distribution, possess either a Dirac point or a Bragg gap in the spectrum of the wavevectors. In particular, we demonstrate that the localization length of the Anderson modes increases when the width of the Bragg gap decreases, such that in the vanishingly small bandgap limit, namely when a Dirac point is formed, even extremely high levels of disorder are unable to localize the optical modes residing near the Dirac point. A comparative analysis of the key features of the propagation of Anderson modes formed in the Bragg gap or near the Dirac point is also presented. Our findings could provide valuable guidelines in assessing the influence of structural disorder on the functionality of a broad array of optical nanodevices. PMID:26498634

  8. Observation of migrating transverse Anderson localizations of light in nonlocal media.

    PubMed

    Leonetti, Marco; Karbasi, Salman; Mafi, Arash; Conti, Claudio

    2014-05-16

    We report the experimental observation of the interaction and attraction of many localized modes in a two-dimensional system realized by a disordered optical fiber supporting transverse Anderson localization. We show that a nonlocal optically nonlinear response of thermal origin alters the localization length by an amount determined by the optical power and also induces an action at a distance between the localized modes and their spatial migration. Evidence of a collective and strongly interacting regime is given. PMID:24877941

  9. Steady-state and dynamical Anderson localization of counterpropagating beams in two-dimensional photonic lattices

    SciTech Connect

    Jovic, Dragana M.; Belic, Milivoj R.

    2010-02-15

    We demonstrate Anderson localization of mutually incoherent counterpropagating beams in an optically induced two-dimensional photonic lattice. The effect is displayed in a system of two broad probe beams propagating head-on through a fixed disordered photonic lattice recorded in a photorefractive crystal. In addition to the steady-state localization, we also observe the dynamical localization; that is, the localization of time-changing beams. As compared to the localization of single beams, in which there exist no dynamical effects, the localization of counterpropagating beams is more pronounced and prone to instabilities.

  10. Properties of a localized magnetic impurity in a superconducting host: The Anderson-Holstein-BCS model

    NASA Astrophysics Data System (ADS)

    Narasimha Raju, Ch.; Chatterjee, Ashok

    2015-12-01

    A symmetric Anderson-Holstein model with a BCS interaction term is considered to investigate the effect of local electron-phonon interaction on a magnetic impurity in a superconductor. The Kikuchi-Morita Cluster variation (CV) method is used to calculate the local impurity magnetic moment and the binding energy between the impurity and the conduction electrons in the superconductor. The effect of electron-phonon interaction and the order parameter on the bound state is discussed.

  11. Observation of Anderson Localization in Ultrathin Films of Three-Dimensional Topological Insulators

    NASA Astrophysics Data System (ADS)

    Liao, Jian; Ou, Yunbo; Feng, Xiao; Yang, Shuo; Lin, Chaojing; Yang, Wenmin; Wu, Kehui; He, Ke; Ma, Xucun; Xue, Qi-Kun; Li, Yongqing

    2015-05-01

    Anderson localization, the absence of diffusive transport in disordered systems, has been manifested as hopping transport in numerous electronic systems, whereas in recently discovered topological insulators it has not been directly observed. Here, we report experimental demonstration of a crossover from diffusive transport in the weak antilocalization regime to variable range hopping transport in the Anderson localization regime with ultrathin (Bi1 -xSbx)2Te3 films. As disorder becomes stronger, negative magnetoconductivity due to the weak antilocalization is gradually suppressed, and eventually, positive magnetoconductivity emerges when the electron system becomes strongly localized. This work reveals the critical role of disorder in the quantum transport properties of ultrathin topological insulator films, in which theories have predicted rich physics related to topological phase transitions.

  12. Anderson localization in optical lattices with speckle disorder

    SciTech Connect

    Sucu, Serpil; Aktas, Saban; Okan, S. Erol; Akdeniz, Zehra; Vignolo, Patrizia

    2011-12-15

    We study the localization properties of noninteracting waves propagating in a speckle-like potential superposed on a one-dimensional lattice. Using a combined decimation-renormalization procedure, we estimate the localization length for a tight-binding Hamiltonian where site energies are square-sinc-correlated random variables. By decreasing the width of the correlation function, the disorder patterns approach a {delta}-correlated disorder, and the localization length becomes almost energy independent in the strong disorder limit. We show that this regime can be reached for a size of the speckle grains on the order of (lower than) four lattice steps.

  13. Evolution of locally excited avalanches in semiconductors

    E-print Network

    Z. L. Yuan; J. F. Dynes; A. W. Sharpe; A. J. Shields

    2010-05-25

    We show that semiconductor avalanche photodiodes can exhibit diminutive amplification noise during the early evolution of avalanches. The noise is so low that the number of locally excited charges that seed each avalanche can be resolved. These findings constitute an important first step towards realization of a solid-state noiseless amplifier. Moreover, we believe that the experimental setup used, \\textit{i.e.}, time-resolving locally excited avalanches, will become a useful tool for optimizing the number resolution.

  14. Anderson localization and topological transition in Chern insulators

    NASA Astrophysics Data System (ADS)

    Castro, Eduardo V.; López-Sancho, M. Pilar; Vozmediano, María A. H.

    2015-08-01

    We analyze the topological transition and localization evolution of disordered two-dimensional systems with nontrivial topology based on bipartite lattices. Chern insulators with broken time-reversal symmetry show nonstandard behavior for disorder realizations selectively distributed on only one of the sublattices. The Chern number survives to a much stronger disorder strength (one order of magnitude higher) than in the equally distributed disordered case, and the final state in the strongly disordered case is metallic.

  15. Simulation of Anderson localization in two-dimensional ultracold gases for pointlike disorder

    NASA Astrophysics Data System (ADS)

    Morong, W.; DeMarco, B.

    2015-08-01

    Anderson localization has been observed for a variety of media, including ultracold atomic gases with speckle disorder in one and three dimensions. However, observation of Anderson localization in a two-dimensional geometry for ultracold gases has been elusive. We show that a cause of this difficulty is the relatively high percolation threshold of a speckle potential in two dimensions, resulting in strong classical localization. We propose a realistic pointlike disorder potential that circumvents this percolation limit with localization lengths that are experimentally observable. The percolation threshold is evaluated for experimentally realistic parameters, and a regime of negligible classical trapping is identified. Localization lengths are determined via scaling theory, using both exact scattering cross sections and the Born approximation, and by direct simulation of the time-dependent Schrödinger equation. We show that the Born approximation can underestimate the localization length by four orders of magnitude at low energies, while exact cross sections and scaling theory provide an upper bound. Achievable experimental parameters for observing localization in this system are proposed.

  16. Anderson localization and Brewster anomalies in photonic disordered quasiperiodic lattices

    SciTech Connect

    Reyes-Gomez, E.; Bruno-Alfonso, A.; Cavalcanti, S. B.; Oliveira, L. E.

    2011-09-15

    A comprehensive study of the properties of light propagation through one-dimensional photonic disordered quasiperiodic superlattices, composed of alternating layers with random thicknesses of air and a dispersive metamaterial, is theoretically performed. The superlattices consist of the successive stacking of N quasiperiodic Fibonacci or Thue-Morse heterostructures. The width of the slabs in the photonic superlattice may randomly fluctuate around its mean value, which introduces a structural disorder into the system. It is assumed that the left-handed layers have a Drude-type dispersive response for both the dielectric permittivity and magnetic permeability, and Maxwell's equations are solved for oblique incidence by using the transfer-matrix formalism. The influence of both quasiperiodicity and structural disorder on the localization length and Brewster anomalies are thoroughly discussed.

  17. Ensemble-Averaged Quantum Correlations between Path-Entangled Photons Undergoing Anderson Localization

    NASA Astrophysics Data System (ADS)

    Gilead, Yehonatan; Verbin, Mor; Silberberg, Yaron

    2015-09-01

    We measure ensemble-averaged quantum correlations of path-entangled photons, propagating in a disordered lattice and undergoing Anderson localization. These result in intriguing patterns, which show that quantum interference leads to unexpected dependencies of the location of one particle on the location of the other. These correlations are shared between localized and nonlocalized components of the two-photon wave function, and, moreover, yield information regarding the nature of the disorder itself. Such effects cannot be reproduced with classical waves, and are undetectable without ensemble averaging.

  18. Perfect absorption in nanotextured thin films via Anderson-localized photon modes

    NASA Astrophysics Data System (ADS)

    Aeschlimann, Martin; Brixner, Tobias; Differt, Dominik; Heinzmann, Ulrich; Hensen, Matthias; Kramer, Christian; Lükermann, Florian; Melchior, Pascal; Pfeiffer, Walter; Piecuch, Martin; Schneider, Christian; Stiebig, Helmut; Strüber, Christian; Thielen, Philip

    2015-10-01

    The enhancement of light absorption in absorber layers is crucial in a number of applications, including photovoltaics and thermoelectrics. The efficient use of natural resources and physical constraints such as limited charge extraction in photovoltaic devices require thin but efficient absorbers. Among the many different strategies used, light diffraction and light localization at randomly nanotextured interfaces have been proposed to improve absorption. Although already exploited in commercial devices, the enhancement mechanism for devices with nanotextured interfaces is still subject to debate. Using coherent two-dimensional nanoscopy and coherent light scattering, we demonstrate the existence of localized photonic states in nanotextured amorphous silicon layers as used in commercial thin-film solar cells. Resonant absorption in these states accounts for the enhanced absorption in the long-wavelength cutoff region. Our observations establish that Anderson localization—that is, strong localization—is a highly efficient resonant absorption enhancement mechanism offering interesting opportunities for the design of efficient future absorber layers.

  19. Anderson Localization and the Quantum Phase Diagram of Three Dimensional Disordered Dirac Semimetals

    NASA Astrophysics Data System (ADS)

    Pixley, J. H.; Goswami, Pallab; Das Sarma, S.

    2015-08-01

    We study the quantum phase diagram of a three dimensional noninteracting Dirac semimetal in the presence of either quenched axial or scalar potential disorder, by calculating the average and the typical density of states as well as the inverse participation ratio using numerically exact methods. We show that as a function of the disorder strength a half-filled (i.e., undoped) Dirac semimetal displays three distinct ground states, namely an incompressible semimetal, a compressible diffusive metal, and a localized Anderson insulator, in stark contrast to a conventional dirty metal that only supports the latter two phases. We establish the existence of two distinct quantum critical points, which respectively govern the semimetal-metal and the metal-insulator quantum phase transitions and also reveal their underlying multifractal nature. Away from half-filling the (doped) system behaves as a diffusive metal that can undergo Anderson localization only, which is shown by determining the mobility edge and the phase diagram in terms of energy and disorder.

  20. One-dimensional Anderson Localization: distribution of wavefunction amplitude and phase at the band center

    SciTech Connect

    Kravtsov, V. E.; Yudson, V. I.

    2009-05-14

    The statistics of normalized wavefunctions in the one-dimensional (1d) Anderson model of localization is considered. It is shown that at any energy that corresponds to a rational filling factor f = (p/q) there is a statistical anomaly which is seen in expansion of the generating function (GF) to the order q-2 in the disorder parameter. We study in detail the principle anomaly at f = (1/2) that appears in the leading order. The transfer-matrix equation of the Fokker-Planck type with a two-dimensional internal space is derived for GF. It is shown that the zero-mode variant of this equation is integrable and a solution for the generating function is found in the thermodynamic limit.

  1. Localized excitations in UPdSn

    SciTech Connect

    Nakotte, H.; Robinson, R.A.; Swan, T.; Kelley, T.; Bull, M.; McEwen, K.A.; Ecclestone, R.A.; Brueck, E.

    1997-11-01

    The authors have measured the inelastic neutron-scattering response of UPdSn at various temperatures using the HET and PHAROS spectrometers at the ISIS and MLNSC facilities, respectively. UPdSn shows some quasielastic scattering, which may be attributed to the hybridization of the 5f electrons with the conduction electrons. Furthermore, they find a clear excitation around 40meV above 40K in addition to the phonon contribution. While this excitation may be indicative of crystal fields in UPdSn, its strong temperature dependence seems to contradict a simple crystal-field picture. Below T{sub N}, the unusual temperature dependence may be attributed to magnetically-driven distortions (and subsequent changes in the local surrounding of the U ions), but there is some evidence that other additional mechanism(s) may contribute above T{sub N}. Some possible mechanisms will be discussed.

  2. Dual nature of localization in guiding systems with randomly corrugated boundaries: Anderson-type versus entropic

    NASA Astrophysics Data System (ADS)

    Tarasov, Yu. V.; Shostenko, L. D.

    2015-05-01

    A unified theory for the conductance of an infinitely long multimode quantum wire whose finite segment has randomly rough lateral boundaries is developed. It enables one to rigorously take account of all feasible mechanisms of wave scattering, both related to boundary roughness and to contacts between the wire rough section and the perfect leads within the same technical frameworks. The rough part of the conducting wire is shown to act as a mode-specific randomly modulated effective potential barrier whose height is governed essentially by the asperity slope. The mean height of the barrier, which is proportional to the average slope squared, specifies the number of conducting channels. Under relatively small asperity amplitude this number can take on arbitrary small, up to zero, values if the asperities are sufficiently sharp. The consecutive channel cut-off that arises when the asperity sharpness increases can be regarded as a kind of localization, which is not related to the disorder per se but rather is of entropic or (equivalently) geometric origin. The fluctuating part of the effective barrier results in two fundamentally different types of guided wave scattering, viz., inter- and intramode scattering. The intermode scattering is shown to be for the most part very strong except in the cases of (a) extremely smooth asperities, (b) excessively small length of the corrugated segment, and (c) the asperities sharp enough for only one conducting channel to remain in the wire. Under strong intermode scattering, a new set of conducting channels develops in the corrugated waveguide, which have the form of asymptotically decoupled extended modes subject to individual solely intramode random potentials. In view of this fact, two transport regimes only are realizable in randomly corrugated multimode waveguides, specifically, the ballistic and the localized regime, the latter characteristic of one-dimensional random systems. Two kinds of localization are thus shown to coexist in waveguide-like systems with randomly corrugated boundaries, specifically, the entropic localization and the one-dimensional Anderson (disorder-driven) localization. If the particular mode propagates across the rough segment ballistically, the Fabry-Pérot-type oscillations should be observed in the conductance, which are suppressed for the mode transferred in the Anderson-localized regime.

  3. Commensurability effects in one-dimensional Anderson localization: Anomalies in eigenfunction statistics

    SciTech Connect

    Kravtsov, V.E.; Yudson, V.I.

    2011-07-15

    Highlights: > Statistics of normalized eigenfunctions in one-dimensional Anderson localization at E = 0 is studied. > Moments of inverse participation ratio are calculated. > Equation for generating function is derived at E = 0. > An exact solution for generating function at E = 0 is obtained. > Relation of the generating function to the phase distribution function is established. - Abstract: The one-dimensional (1d) Anderson model (AM), i.e. a tight-binding chain with random uncorrelated on-site energies, has statistical anomalies at any rational point f=(2a)/({lambda}{sub E}) , where a is the lattice constant and {lambda}{sub E} is the de Broglie wavelength. We develop a regular approach to anomalous statistics of normalized eigenfunctions {psi}(r) at such commensurability points. The approach is based on an exact integral transfer-matrix equation for a generating function {Phi}{sub r}(u, {phi}) (u and {phi} have a meaning of the squared amplitude and phase of eigenfunctions, r is the position of the observation point). This generating function can be used to compute local statistics of eigenfunctions of 1d AM at any disorder and to address the problem of higher-order anomalies at f=p/q with q > 2. The descender of the generating function P{sub r}({phi}){identical_to}{Phi}{sub r}(u=0,{phi}) is shown to be the distribution function of phase which determines the Lyapunov exponent and the local density of states. In the leading order in the small disorder we derived a second-order partial differential equation for the r-independent ('zero-mode') component {Phi}(u, {phi}) at the E = 0 (f=1/2 ) anomaly. This equation is nonseparable in variables u and {phi}. Yet, we show that due to a hidden symmetry, it is integrable and we construct an exact solution for {Phi}(u, {phi}) explicitly in quadratures. Using this solution we computed moments I{sub m} = N< vertical bar {psi} vertical bar {sup 2m}> (m {>=} 1) for a chain of the length N {yields} {infinity} and found an essential difference between their m-behavior in the center-of-band anomaly and for energies outside this anomaly. Outside the anomaly the 'extrinsic' localization length defined from the Lyapunov exponent coincides with that defined from the inverse participation ratio ('intrinsic' localization length). This is not the case at the E = 0 anomaly where the extrinsic localization length is smaller than the intrinsic one. At E = 0 one also observes an anomalous enhancement of large moments compatible with existence of yet another, much smaller characteristic length scale.

  4. Anderson localization enhanced ferromagnetism in Zn0.95Co0.05O

    NASA Astrophysics Data System (ADS)

    Snure, Michael; Tiwari, Ashutosh

    2009-08-01

    We report an enhancement in the ferromagnetic characteristics of Zn0.95Co0.05O thin films due to the localization of charge carriers. Epitaxial thin films of Zn0.95-xCo0.05GaxO (x =0-0.05) were grown on single-crystal sapphire (0001) substrates by pulsed laser deposition technique. The role of charge carrier localization on the electrical and magnetic properties of ZnO:Co was studied by introducing Ga into the system. It was observed that Ga plays a significant role in affecting both the electrical transport mechanism as well as the magnetization of the material. Electrical resistivity of Zn0.95Co0.05O at room temperature was ˜96 m? cm and exhibited metal-like temperature dependence, although strongly influenced by electron-electron (e-e) interactions. Strong e-e interaction was understood to arise because of the randomness introduced in the crystal potential of ZnO by the cobalt dopants. As the Ga dopants are introduced, randomness in crystal potential and hence the disorder further increases resulting in the Anderson localization of the carriers. The increase in localization was accompanied by a significant enhancement in the magnetic moment from 0.75?B/Co in Zn0.95Co0.05O films to 1.6?B/Co in Zn0.90Co0.05Ga0.05O.

  5. Disorder-induced trapping versus Anderson localization in Bose-Einstein condensates expanding in disordered potentials

    E-print Network

    Laurent Sanchez-Palencia; David Clément; Pierre Lugan; Philippe Bouyer; Alain Aspect

    2008-05-01

    We theoretically investigate the localization of an expanding Bose-Einstein condensate with repulsive atom-atom interactions in a disordered potential. We focus on the regime where the initial inter-atomic interactions dominate over the kinetic energy and the disorder. At equilibrium in a trapping potential and for small disorder, the condensate shows a Thomas-Fermi shape modified by the disorder. When the condensate is released from the trap, a strong suppression of the expansion is obtained in contrast to the situation in a periodic potential with similar characteristics. This effect crucially depends on both the momentum distribution of the expanding BEC and the strength of the disorder. For strong disorder, the suppression of the expansion results from the fragmentation of the core of the condensate and from classical reflections from large modulations of the disordered potential in the tails of the condensate. We identify the corresponding disorder-induced trapping scenario for which large atom-atom interactions and strong reflections from single modulations of the disordered potential play central roles. For weak disorder, the suppression of the expansion signals the onset of Anderson localization, which is due to multiple scattering from the modulations of the disordered potential. We compute analytically the localized density profile of the condensate and show that the localization crucially depends on the correlation function of the disorder. In particular, for speckle potentials the long-range correlations induce an effective mobility edge in 1D finite systems. Numerical calculations performed in the mean-field approximation support our analysis for both strong and weak disorder.

  6. A non-Monte Carlo approach to analyzing 1D Anderson localization in dispersive metamaterials

    NASA Astrophysics Data System (ADS)

    Kissel, Glen J.

    2015-09-01

    Monte Carlo simulations have long been used to study Anderson localization in models of one-dimensional random stacks. Because such simulations use substantial computational resources and because the randomness of random number generators for such simulations has been called into question, a non-Monte Carlo approach is of interest. This paper uses a non-Monte Carlo methodology, limited to discrete random variables, to determine the Lyapunov exponent, or its reciprocal, known as the localization length, for a one-dimensional random stack model, proposed by Asatryan, et al., consisting of various combinations of negative, imaginary and positive index materials that include the effects of dispersion and absorption, as well as off-axis incidence and polarization effects. Dielectric permittivity and magnetic permeability are the two variables randomized in the models. In the paper, Furstenberg's integral formula is used to calculate the Lyapunov exponent of an infinite product of random matrices modeling the one-dimensional stack. The integral formula requires integration with respect to the probability distribution of the randomized layer parameters, as well as integration with respect to the so-called invariant probability measure of the direction of the vector propagated by the long chain of random matrices. The non-Monte Carlo approach uses a numerical procedure of Froyland and Aihara which calculates the invariant measure as the left eigenvector of a certain sparse row-stochastic matrix, thus avoiding the use of any random number generator. The results show excellent agreement with the Monte Carlo generated simulations which make use of continuous random variables, while frequently providing reductions in computation time.

  7. Coherent state, local excitation in 2D conformal field theory

    E-print Network

    Wu-Zhong Guo

    2015-10-24

    In this paper we discuss the topics concerning the local excitation and coherent state in 2D CFT. It is shown that the local excitation of primary operator can be taken as a coherent state of the global conformal group. We also discuss the entanglement property of such state. For rational CFT the entanglement entropy between the holomorphic and anti-holomorphic sector of the local excitation of some primary operator is related to the quantum dimension of the operator, consistent with previous approach, but by a differentmethod. We comment on the possible application of so-defined group coherent state in the holographic view. We also study the coherent state in the free massless boson field, their time evolution and entanglement property. We introduce the deformed local excitation and the entangled state constructed by them. It is shown the violation of Bell inequality for such entangled state.

  8. Coherent state, local excitation in 2D conformal field theory

    E-print Network

    Guo, Wu-Zhong

    2015-01-01

    In this paper we discuss the topics concerning the local excitation and coherent state in 2D CFT. It is shown that the local excitation of primary operator can be taken as a coherent state of the global conformal group. We also discuss the entanglement property of such state. For rational CFT the entanglement entropy between the holomorphic and anti-holomorphic sector of the local excitation of some primary operator is related to the quantum dimension of the operator, consistent with previous approach, but by a differentmethod. We comment on the possible application of so-defined group coherent state in the holographic view. We also study the coherent state in the free massless boson field, their time evolution and entanglement property. We introduce the deformed local excitation and the entangled state constructed by them. It is shown the violation of Bell inequality for such entangled state.

  9. Local Blockade of Rydberg Excitation in an Ultracold Gas

    NASA Astrophysics Data System (ADS)

    Tong, D.; Farooqi, S. M.; Stanojevic, J.; Krishnan, S.; Zhang, Y. P.; Côté, R.; Eyler, E. E.; Gould, P. L.

    2004-08-01

    In the laser excitation of ultracold atoms to Rydberg states, we observe a dramatic suppression caused by van der Waals interactions. This behavior is interpreted as a local excitation blockade: Rydberg atoms strongly inhibit excitation of their neighbors. We measure suppression, relative to isolated atom excitation, by up to a factor of 6.4. The dependences of this suppression on both laser irradiance and atomic density are in good agreement with a mean-field model. These results are an important step towards using ultracold Rydberg atoms in quantum information processing.

  10. Dual hidden landscapes in Anderson localization on discrete lattices Instituto de Fisica, Universidade Federal de Alagoas, 57072-970 Maceio, AL, Brazil

    E-print Network

    Mayboroda, Svitlana

    Dual hidden landscapes in Anderson localization on discrete lattices M.L.Lyra Instituto de F in continuous disordered media have been recently demon- strated to be governed by a hidden landscape localization confinement is determined by this landscape, and continuously decreases as the energy increases

  11. Emergence of Asynchronous Local Clocks in Excitable Media

    PubMed Central

    Gerum, Richard Carl; Fabry, Ben; Metzner, Claus

    2015-01-01

    Excitable media such as the myocardium or the brain consist of arrays of coupled excitable elements, in which the local excitation of a single element can propagate to its neighbors in the form of a non-linear autowave. Since each element has to pass through a refractory period immediately after excitation, the frequency of autowaves is self-limiting. In this work, we consider the case where each element is spontaneously excited at a fixed average rate and thereby initiates a new autowave. Although these spontaneous self-excitation events are modelled as independent Poisson point processes with exponentially distributed waiting times, the travelling autowaves lead collectively to a non-exponential, unimodal waiting time distribution for the individual elements. With increasing system size, a global ‘clock’ period T emerges as the most probable waiting time for each element, which fluctuates around T with an increasingly small but non-zero variance. This apparent synchronization between asynchronous, temporally uncorrelated point processes differs from synchronization effects between perfect oscillators interacting in a phase-aligning manner. Finally, we demonstrate that asynchronous local clocks also emerge in non-homogeneous systems in which the rates of self-excitation are different for all individuals, suggesting that this novel mechanism can occur in a wide range of excitable media. PMID:26559528

  12. Transverse Chiral Optical Forces by Locally Excited Surface Plasmon Polaritons

    E-print Network

    Alizadeh, M H

    2015-01-01

    Recently the new concepts of transverse spin angular momentum and Belinfante spin momentum of evanescent waves have drawn considerable attention. Here, we investigate these novel physical properties of electromagnetic fields in the context of locally excited surface plasmon polaritons. We demonstrate, both analytically and numerically, that locally excited surface plasmon polaritons possess transverse spin angular momentum and Belinfante momentum with rich and non-trivial characteristics. We also show that the transverse spin angular momentum of locally excited surface plasmon polaritons leads to the emergence of transverse chiral forces in opposite directions for chiral objects of different handedness. The magnitude of such a transverse force is comparable to the optical gradient force and scattering forces. This finding may pave the way for realization of optical separation of chiral biomolecules.

  13. Geometry of the localized ??? excited state of n-tetrasilane

    NASA Astrophysics Data System (ADS)

    Teramae, Hiroyuki; Michl, Josef

    1997-09-01

    Full optimization of the geometry of the lowest excited singlet of n-tetrasilane, Si 4H 10, at several levels of CASSCF theory yielded a floppy C 2 structure with an SiSiSiSi dihedral angle of 105° that can be increased to 180° at the cost of only 4 kcal/mol, SiSiSi valence angles of 90°, central SiSi bond stretched to 2.55 Å and terminal ones to 2.42 Å. The ??? excitation is localized in the central bond.

  14. Electrically excited, localized infrared emission from single carbon nanotubes.

    PubMed

    Freitag, Marcus; Tsang, James C; Kirtley, John; Carlsen, Autumn; Chen, Jia; Troeman, Aico; Hilgenkamp, Hans; Avouris, Phaedon

    2006-07-01

    Carbon nanotube field-effect transistors (CNTFETs) produce band gap derived infrared emission under both ambipolar and unipolar transport conditions. We demonstrate here that heterogeneities/defects in the local environment of a CNTFET perturb the local potentials and, as a result, the characteristic bias dependent motion of the ambipolar light emission. Such defects can also introduce localized infrared emission due to impact excitation by carriers accelerated by a voltage drop at the defect. The correlation of the change in the motion of the ambipolarlight emission and of the stationary electroluminescence with the electrical characteristics of the CNTFETs shows that stationaryelectroluminescence can identify "environmental defects" in carbon nanotubes and help evaluate their influence on electrical transport and device operation. A number of different defects are studied involving local dielectric environment changes (partially polymer-covered nanotubes), nanotube-nanotube contacts in looped nanotubes, and nanotube segments close to the electronic contacts. Random defects due to local charging are also observed. PMID:16834423

  15. Enhanced Electromagnetic Chirality by Locally Excited Surface Plasmon Polaritons

    E-print Network

    Alizadeh, M H

    2015-01-01

    The possibility to enhance chiral light-matter interactions through plasmonic nanostructures provides entirely new opportunities for greatly improving the detection limits of chiroptical spectroscopies down to the single molecule level. The most pronounced of these chiral interactions occur in the ultraviolet (UV) range of the electromagnetic spectrum, which is difficult to access with conventional localized plasmon resonance based sensors. Although Surface Plasmon Polaritons (SPPs) on noble metal films can sustain resonances in the desired spectral range, their transverse magnetic nature has been an obstacle for enhancing chiroptical effects. Here we demonstrate, both analytically and numerically, that SPPs excited by near-field sources can exhibit rich and non-trivial chiral characteristics. In particular, we show that the excitation of SPPs by a chiral source not only results in a locally enhanced optical chirality but also achieves manifold enhancement of net optical chirality. Our finding that SPPs facil...

  16. High Speed Switch Scheduling for Local Area Networks Thomas E. Anderson

    E-print Network

    Anderson, Tom

    performance distributed computing. Advances in laser and fiber optic technology have driven feasible link of datagram traffic. We describe a technique called statistical matching, which can be used to ensure fairness to construct a practical local area network using multiple switches and gigabit­per­second point­to­point fiber

  17. Relativistic Coulomb excitation within Time Dependent Superfluid Local Density Approximation

    E-print Network

    I. Stetcu; C. Bertulani; A. Bulgac; P. Magierski; K. J. Roche

    2015-01-13

    Within the framework of the unrestricted time-dependent density functional theory, we present for the first time an analysis of the relativistic Coulomb excitation of the heavy deformed open shell nucleus $^{238}$U. The approach is based on Superfluid Local Density Approximation (SLDA) formulated on a spatial lattice that can take into account coupling to the continuum, enabling self-consistent studies of superfluid dynamics of any nuclear shape. We have computed the energy deposited in the target nucleus as a function of the impact parameter, finding it to be significantly larger than the estimate using the Goldhaber-Teller model. The isovector giant dipole resonance, the dipole pygmy resonance and giant quadrupole modes were excited during the process. The one body dissipation of collective dipole modes is shown to lead a damping width $\\Gamma_\\downarrow \\approx 0.4$ MeV and the number of pre-equilibrium neutrons emitted has been quantified.

  18. Excitability Mediated by Localized Structures in a Dissipative Nonlinear Optical Cavity Damia` Gomila,* Manuel A. Matias,

    E-print Network

    Gomila, Damià

    Excitability Mediated by Localized Structures in a Dissipative Nonlinear Optical Cavity Damia 18 February 2005) We find and characterize an excitability regime mediated by localized structures-loop bifurcation. Beyond this point there is a regime of excitable localized structures under the application

  19. Anderson Localization of Ballooning Modes, Quantum Chaos and the Stability of Compact Quasiaxially Symmetric Stellarators

    SciTech Connect

    M.H. Redi; J.L. Johnson; S. Klasky; J. Canik; R.L. Dewar; W.A. Cooper

    2001-10-31

    The radially local magnetohydrodynamic (MHD) ballooning stability of a compact, quasiaxially symmetric stellarator (QAS), is examined just above the ballooning beta limit with a method that can lead to estimates of global stability. Here MHD stability is analyzed through the calculation and examination of the ballooning mode eigenvalue isosurfaces in the 3-space [s, alpha, theta(subscript ''k'')]; s is the edge normalized toroidal flux, alpha is the field line variable, and q(subscript ''k'') is the perpendicular wave vector or ballooning parameter. Broken symmetry, i.e., deviations from axisymmetry, in the stellarator magnetic field geometry causes localization of the ballooning mode eigenfunction, and gives rise to new types of nonsymmetric eigenvalue isosurfaces in both the stable and unstable spectrum. For eigenvalues far above the marginal point, isosurfaces are topologically spherical, indicative of strong ''quantum chaos.'' The complexity of QAS marginal isosurfaces suggests that finite Larmor radius stabilization estimates will be difficult and that fully three-dimensional, high-n MHD computations are required to predict the beta limit.

  20. A rigorous replica trick approach to Anderson localization in one dimension

    NASA Astrophysics Data System (ADS)

    Klein, Abel; Martinelli, Fabio; Perez, J. Fernando

    1986-12-01

    Let H=- ?+V on l 2(?), where V( x), x??, are i.i.d.r.v.'s, and let G L ( x, y; E+ i?)= < x|( H L-( E+ i?))-1| y>, where H L denotes the operator H restricted to {-L, -L+1,..., L} with Dirichlet boundary conditions. We use a supersymmetric replica trick to prove that 220_2005_Article_BF01463399_TeX2GIFE1.gif E(|G_L (0,x; E + i? )|^2 ) ?q K? ^{ - 2} exp \\{ - m|log ? |^{ - ? } |x|\\} for some m>0, ?>0, Klocalization by the Fröhlich, Martinelli, Scoppola, and Spencer method.

  1. Weak chaos in the disordered nonlinear Schroedinger chain: Destruction of Anderson localization by Arnold diffusion

    SciTech Connect

    Basko, D.M.

    2011-07-15

    Research Highlights: > In a one-dimensional disordered chain of oscillators all normal modes are localized. > Nonlinearity leads to chaotic dynamics. > Chaos is concentrated on rare chaotic spots. > Chaotic spots drive energy exchange between oscillators. > Macroscopic transport coefficients are obtained. - Abstract: The subject of this study is the long-time equilibration dynamics of a strongly disordered one-dimensional chain of coupled weakly anharmonic classical oscillators. It is shown that chaos in this system has a very particular spatial structure: it can be viewed as a dilute gas of chaotic spots. Each chaotic spot corresponds to a stochastic pump which drives the Arnold diffusion of the oscillators surrounding it, thus leading to their relaxation and thermalization. The most important mechanism of equilibration at long distances is provided by random migration of the chaotic spots along the chain, which bears analogy with variable-range hopping of electrons in strongly disordered solids. The corresponding macroscopic transport equations are obtained.

  2. Unusual magneto-optical behavior induced by local dielectric variations under localized surface plasmon excitations.

    PubMed

    González-Díaz, Juan B; García-Martín, Antonio; Reig, Gaspar Armelles

    2011-01-01

    We study the effect of global and local dielectric variations on the polarization conversion rps response of ordered nickel nanowires embedded in an alumina matrix. When considering local changes, we observe a non-monotonous behavior of the rps, its intensity unusually modified far beyond to what it is expected for a monotonous change of the whole refractive index of the embedding medium. This is related to the local redistribution of the electromagnetic field when a localized surface plasmon is excited. This finding may be employed to develop and improve new biosensing magnetoplasmonic devices. PMID:21711939

  3. Parametric excitation of multiple resonant radiations from localized wavepackets.

    PubMed

    Conforti, Matteo; Trillo, Stefano; Mussot, Arnaud; Kudlinski, Alexandre

    2015-01-01

    Fundamental physical phenomena such as laser-induced ionization, driven quantum tunneling, Faraday waves, Bogoliubov quasiparticle excitations, and the control of new states of matter rely on time-periodic driving of the system. A remarkable property of such driving is that it can induce the localized (bound) states to resonantly couple to the continuum. Therefore experiments that allow for enlightening and controlling the mechanisms underlying such coupling are of paramount importance. We implement such an experiment in a special optical fiber characterized by a dispersion oscillating along the propagation coordinate, which mimics "time". The quasi-momentum associated with such periodic perturbation is responsible for the efficient coupling of energy from the localized wave-packets (solitons in anomalous dispersion and shock fronts in normal dispersion) sustained by the fiber nonlinearity, into free-running linear dispersive waves (continuum) at multiple resonant frequencies. Remarkably, the observed resonances can be explained by means of a unified approach, regardless of the fact that the localized state is a soliton-like pulse or a shock front. PMID:25801054

  4. Parametric excitation of multiple resonant radiations from localized wavepackets

    PubMed Central

    Conforti, Matteo; Trillo, Stefano; Mussot, Arnaud; Kudlinski, Alexandre

    2015-01-01

    Fundamental physical phenomena such as laser-induced ionization, driven quantum tunneling, Faraday waves, Bogoliubov quasiparticle excitations, and the control of new states of matter rely on time-periodic driving of the system. A remarkable property of such driving is that it can induce the localized (bound) states to resonantly couple to the continuum. Therefore experiments that allow for enlightening and controlling the mechanisms underlying such coupling are of paramount importance. We implement such an experiment in a special optical fiber characterized by a dispersion oscillating along the propagation coordinate, which mimics “time”. The quasi-momentum associated with such periodic perturbation is responsible for the efficient coupling of energy from the localized wave-packets (solitons in anomalous dispersion and shock fronts in normal dispersion) sustained by the fiber nonlinearity, into free-running linear dispersive waves (continuum) at multiple resonant frequencies. Remarkably, the observed resonances can be explained by means of a unified approach, regardless of the fact that the localized state is a soliton-like pulse or a shock front. PMID:25801054

  5. Probing the Locality of Excited States with Linear Algebra.

    PubMed

    Etienne, Thibaud

    2015-04-14

    This article reports a novel theoretical approach related to the analysis of molecular excited states. The strategy introduced here involves gathering two pieces of physical information, coming from Hilbert and direct space operations, into a general, unique quantum mechanical descriptor of electronic transitions' locality. Moreover, the projection of Hilbert and direct space-derived indices in an Argand plane delivers a straightforward way to visually probe the ability of a dye to undergo a long- or short-range charge-transfer. This information can be applied, for instance, to the analysis of the electronic response of families of dyes to light absorption by unveiling the trend of a given push-pull chromophore to increase the electronic cloud polarization magnitude of its main transition with respect to the size extension of its conjugated spacer. We finally demonstrate that all the quantities reported in this article can be reliably approximated by a linear algebraic derivation, based on the contraction of detachment/attachment density matrices from canonical to atomic space. This alternative derivation has the remarkable advantage of a very low computational cost with respect to the previously used numerical integrations, making fast and accurate characterization of large molecular systems' excited states easily affordable. PMID:26574379

  6. Excitations Are Localized and Relaxation Is Hierarchical in Glass-Forming Liquids Aaron S. Keys

    E-print Network

    Garrahan, Juan P.

    Excitations Are Localized and Relaxation Is Hierarchical in Glass-Forming Liquids Aaron S. Keys importance sampling of trajectory space to study the structure, statistics, and dynamics of excitations responsible for structural relaxation. Excitations are detected in terms of persistent particle displacements

  7. Leona Anderson Oral History

    E-print Network

    Anderson, Leona; Gadd-Nelson, Rachel

    2009-09-18

    Oral history interview with Leona Anderson conducted by Rachel Gadd-Nelson in Burdick, Kansas, on September 18, 2009. In this interview, Leona Anderson discusses her experiences as a member of the Missouri Synod Lutheran ...

  8. Excitation of Localized Rotating Waves in Plasma Density Cavities by Scattering of Fast Magnetosonic Waves

    E-print Network

    Excitation of Localized Rotating Waves in Plasma Density Cavities by Scattering of Fast Magnetosonic Waves J. O. Hall,1,2 A. I. Eriksson,2 and T. B. Leyser2 1 Department of Astronomy and Space description of electromagnetic waves in an inhomogeneous plasma is applied to investigate excitation

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

    NASA Astrophysics Data System (ADS)

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

    2015-09-01

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

  10. Self-organization of synchronous activity propagation in neuronal networks driven by local excitation

    PubMed Central

    Bayati, Mehdi; Valizadeh, Alireza; Abbassian, Abdolhossein; Cheng, Sen

    2015-01-01

    Many experimental and theoretical studies have suggested that the reliable propagation of synchronous neural activity is crucial for neural information processing. The propagation of synchronous firing activity in so-called synfire chains has been studied extensively in feed-forward networks of spiking neurons. However, it remains unclear how such neural activity could emerge in recurrent neuronal networks through synaptic plasticity. In this study, we investigate whether local excitation, i.e., neurons that fire at a higher frequency than the other, spontaneously active neurons in the network, can shape a network to allow for synchronous activity propagation. We use two-dimensional, locally connected and heterogeneous neuronal networks with spike-timing dependent plasticity (STDP). We find that, in our model, local excitation drives profound network changes within seconds. In the emergent network, neural activity propagates synchronously through the network. This activity originates from the site of the local excitation and propagates through the network. The synchronous activity propagation persists, even when the local excitation is removed, since it derives from the synaptic weight matrix. Importantly, once this connectivity is established it remains stable even in the presence of spontaneous activity. Our results suggest that synfire-chain-like activity can emerge in a relatively simple way in realistic neural networks by locally exciting the desired origin of the neuronal sequence. PMID:26089794

  11. Self-organization of synchronous activity propagation in neuronal networks driven by local excitation.

    PubMed

    Bayati, Mehdi; Valizadeh, Alireza; Abbassian, Abdolhossein; Cheng, Sen

    2015-01-01

    Many experimental and theoretical studies have suggested that the reliable propagation of synchronous neural activity is crucial for neural information processing. The propagation of synchronous firing activity in so-called synfire chains has been studied extensively in feed-forward networks of spiking neurons. However, it remains unclear how such neural activity could emerge in recurrent neuronal networks through synaptic plasticity. In this study, we investigate whether local excitation, i.e., neurons that fire at a higher frequency than the other, spontaneously active neurons in the network, can shape a network to allow for synchronous activity propagation. We use two-dimensional, locally connected and heterogeneous neuronal networks with spike-timing dependent plasticity (STDP). We find that, in our model, local excitation drives profound network changes within seconds. In the emergent network, neural activity propagates synchronously through the network. This activity originates from the site of the local excitation and propagates through the network. The synchronous activity propagation persists, even when the local excitation is removed, since it derives from the synaptic weight matrix. Importantly, once this connectivity is established it remains stable even in the presence of spontaneous activity. Our results suggest that synfire-chain-like activity can emerge in a relatively simple way in realistic neural networks by locally exciting the desired origin of the neuronal sequence. PMID:26089794

  12. Excitation of electron cyclotron harmonic waves in the inner Saturn magnetosphere within local plasma injections

    E-print Network

    Gurnett, Donald A.

    Excitation of electron cyclotron harmonic waves in the inner Saturn magnetosphere within local magnetosphere. Using measured electron distributions from the Cassini plasma spectrometer, we calculated local and their roles in electron dynamics in the Saturnian magnetosphere. Citation: Tao, X., R. M. Thorne, R. B. Horne

  13. Global Optimization with Coupled Local Minimizers Excited by Gaussian White Noise

    E-print Network

    Global Optimization with Coupled Local Minimizers Excited by Gaussian White Noise Serkan G:{serkan.gunel,johan.suykens,joos.vandewalle}@esat.kuleuven.be Abstract--In this paper, Stochastic Coupled Local Minimizers (SCLMs) are presented for global optimization methods for global optimization incorporate random- ness to achieve global exploration of the search space

  14. Exact Three-Body Local Correlations for Excited States of the 1D Bose Gas

    SciTech Connect

    Kormos, Marton; Chou Yangzhi; Imambekov, Adilet

    2011-12-02

    We derive an exact analytic expression for the three-body local correlations in the Lieb-Liniger model of 1D Bose gas with contact repulsion. The local three-body correlations control the thermalization and particle loss rates in the presence of terms which break integrability, as is realized in the case of 1D ultracold bosons. Our result is valid not only at finite temperature but also for a large class of nonthermal excited states in the thermodynamic limit. We present finite temperature calculations in the presence of external harmonic confinement within local density approximation, and for a highly excited state that resembles an experimentally realized configuration.

  15. Localized wake-field excitation and relativistic wave-breaking

    NASA Astrophysics Data System (ADS)

    Lehmann, G.; Laedke, E. W.; Spatschek, K. H.

    2007-10-01

    The localized wake-field behavior behind a short laser pulse is analyzed numerically as well as analytically in one space dimension. A laser pulse propagating in an underdense plasma oscillates in amplitude and width. Within a certain parameter regime, the variations may be near the threshold for wake-field generation. During the times when the width becomes small enough, localized electrostatic wave-packets are generated. The latter may have amplitudes in the relativistic regime. The breaking of the wake-field wave packets is investigated. Known criteria for wave-breaking are generalized to the relativistic and inhomogeneous cases. It is found that relativistic, inhomogeneous packets break without threshold; however, not, in general, on the first oscillation. The time for wave-breaking can be estimated. The numerical findings are proven analytically by making use of a Lagrangian coordinate formulation.

  16. Nuclear charge-exchange excitations in localized covariant density functional theory

    E-print Network

    H. Z. Liang; J. Meng; T. Nakatsukasa; Z. M. Niu; P. Ring; X. Roca-Maza; N. Van Giai; P. W. Zhao

    2013-10-15

    The recent progress in the studies of nuclear charge-exchange excitations with localized covariant density functional theory is briefly presented, by taking the fine structure of spin-dipole excitations in 16O as an example. It is shown that the constraints introduced by the Fock terms of the relativistic Hartree-Fock scheme into the particle-hole residual interactions are straightforward and robust.

  17. Local liquid crystal alignment on patterned micrograting structures photofabricated by two photon excitation direct laser writing

    NASA Astrophysics Data System (ADS)

    Lee, Chee Heng; Yoshida, Hiroyuki; Miura, Yusuke; Fujii, Akihiko; Ozaki, Masanori

    2008-10-01

    The authors demonstrate local alignment of nematic liquid crystal through the fabrication of local micrograting structures by curing an ultraviolet curable material via a two-photon excitation laser-lithography process. A local twisted-nematic region was prepared using one rubbed and one fabricated micrograting surface and the resulting cell was observed with a polarizing optical microscope. The polarization optical micrographs of the locally fabricated region suggest that liquid crystal molecules align parallel to the grating structure and that local alignment is achieved. We evaluate the anchoring energies of the fabricated microgratings by the torque balance method.

  18. Journal of Statistical Physics, 11"ol.75. Nos. 1/2, 1994 Anderson Localization and the Space-Time

    E-print Network

    Stollmann, Peter.

    . There the Green's function is regularized by going to finite volumes; here, by going to complex energies. #12, is the derivation of some form of exponential decay tS) of the Green's function. In a second step, localization, i':'' IIPI.,-I>~Re-i""tP[I-' = iim limLfdEllPN>,R(h-E-iE)-'$ll 2 (2) 8 ~ m elO 7"[J The Green's function

  19. Investigation of RF excited CW CO2 waveguide lasers local oscillator - RF excitation

    NASA Technical Reports Server (NTRS)

    Hochuli, U.

    1988-01-01

    A new local oscillator housing was built which seems to have improved laser life. Laser cooling was changed from internal water cooling to the more convenient thermal contact cooling. At the present time, a conclusion can not be made if the 20 percent reduction in power output is the result of poorer cooling or poorer grating alignment. The coupling-starting network was improved from 55 to about 90 percent. It can be adjusted by varying trimmers C sub 1 and C sub 2 to match RF power levels between 10 and 30 W. If the laser admittance changes greatly with laser life rematching will have to be achieved by remote control for space applications. The same holds true if the RF power level has to be changed with a maximum efficiency constraint.

  20. Rényi entropy of locally excited states with thermal and boundary effect in 2D CFTs

    E-print Network

    Wu-Zhong Guo; Song He

    2015-05-17

    We study R\\'enyi entropy of locally excited states with considering the thermal and boundary effects respectively in two dimensional conformal field theories (CFTs). Firstly we consider locally excited states obtained by acting primary operators on a thermal state in low temperature limit. The R\\'enyi entropy is summation of contribution from thermal effect and local excitation. Secondly, we mainly study the R\\'enyi entropy of locally excited states in 2D CFT with a boundary. We show that the evolution of R\\'enyi entropy does not depend on the choice of boundary conditions and boundary will change the time evolution of R\\'enyi entropy. Moreover, in 2D rational CFTs with a boundary, we show that the R\\'enyi entropy always coincides with the log of quantum dimension of the primary operator during some periods of the evolution. We make use of a quasi-particle picture to understand this phenomenon. In terms of quasi-particle interpretation, the boundary behaves as an infinite potential barrier which reflects any energy moving towards the boundary.

  1. Local excitation of strongly coupled exciton-surface plasmons polaritons by a single nanoantenna

    SciTech Connect

    Eizner, E. Ellenbogen, T.

    2014-06-02

    We demonstrate experimentally local coupling of light from free space to exciton-surface plasmon polaritons (X-SPPs). This is achieved by using a single, sub-wavelength gold nanowire on top of a thin silver film which is covered with a 30?nm thick layer of J-aggregating dyes in polyvinyl alcohol. We show that the nanowire acts as an antenna that resonantly scatters light to X-SPPs states with a Rabi splitting of 0.1?eV. The locally excited X-SPPs properties are studied by angle resolved spectroscopy of the far-field leaky photons and are compared to the large-scale response through Kretschmann reflection measurements and to theoretical calculations. The nanowire scattering properties are studied by dark-field scattering measurements and finite-difference time-domain simulations. This method to locally excite X-SPPs can potentially be useful for future applications of hybrid light matter states.

  2. Local excitation of surface plasmon polaritons using nitrogen-vacancy centers.

    PubMed

    Garcia-Ortiz, Cesar E; Kumar, Shailesh; Bozhevolnyi, Sergey I

    2015-08-15

    Surface plasmon polaritons (SPPs) are locally excited at silver surfaces using (?100) nanometer-sized nanodiamonds (NDs) with multiple nitrogen-vacancy (NV) centers (?400). The fluorescences from an externally illuminated (at 532 nm) ND and from nearby NDs, which are not illuminated but produce out-of-plane scattering of SPPs excited by the illuminated ND, exhibit distinctly different wavelength spectra, showing short-wavelength filtering due to the SPP propagation loss. The results indicate that NDs with multiple NV centers can be used as efficient subwavelength SPP sources in planar integrated plasmonics for various applications. PMID:26274671

  3. Measurement of Localized Electrostatic Oscillations Excited by Low-Power Microwaves in a Plasma Waveguide

    NASA Astrophysics Data System (ADS)

    Minami, Kazuo; Izawa, Koichi; Kaminaga, Masanobu; Ishii, Kazushige

    1986-04-01

    Localized electron plasma oscillations excited at the resonant surface by low-power microwaves incident obliquely on an inhomogeneous unmagnetized plasma in a cylindrical waveguide are measured by a receiving antenna. The disturbance by the antenna on the electrostatic fields is significantly reduced in our condition with a steep density gradient and large angles of incidence. As a result, patterns of large and broad resonance field including phase information are observed. The peak values of the resonantly excited field are compared with numerical analyses.

  4. Measurement of localized electrostatic oscillations excited by low-power microwaves in a plasma waveguide

    NASA Astrophysics Data System (ADS)

    Minami, K.; Izawa, K.; Kaminaga, M.; Ishii, K.

    1986-06-01

    Localized electron plasma oscillations excited at the resonant surface by low-power microwaves incident obliquely on an inhomogeneous unmagnetized plasma in a cylindrical waveguide are measured by a receiving antenna. The disturbance by the antenna on the electrostatic fields is significantly reduced in the condition with a steep density gradient and large angles of incidence. As a result, patterns of large and broad resonance field including phase information are observed. The peak values of the resonantly excited field are compared with numerical analyses.

  5. Specific heat of a localized magnetic impurity in a non-magnetic host: A spectral density method for the Anderson-Holstein model

    NASA Astrophysics Data System (ADS)

    Raju, Ch. Narasimha; Chatterjee, Ashok

    2015-10-01

    The effect of electron-phonon interaction on the spectral function of a magnetic impurity in a non-magnetic host metal is studied within the framework of the Anderson-Holstein model using a spectral density method. The impurity contribution to the specific heat of the host metal is also calculated.

  6. PexLoc-Parallel excitation using local encoding magnetic fields with nonlinear and nonbijective spatial profiles.

    PubMed

    Haas, M; Ullmann, P; Schneider, J T; Post, H; Ruhm, W; Hennig, J; Zaitsev, M

    2013-11-01

    With the recent proposal of using magnetic fields that are nonlinear by design for spatial encoding, new flexibility has been introduced to MR imaging. The new degrees of freedom in shaping the spatially encoding magnetic fields (SEMs) can be used to locally adapt the imaging resolution to features of the imaged object, e.g., anatomical structures, to reduce peripheral nerve stimulation during in vivo experiments or to increase the gradient switching speed by reducing the inductance of the coils producing the SEMs and thus accelerate the imaging process. In this work, the potential of nonlinear and nonbijective SEMs for spatial encoding during transmission in multidimensional spatially selective excitation is explored. Methods for multidimensional spatially selective excitation radiofrequency pulse design based on nonlinear encoding fields are introduced, and it is shown how encoding ambiguities can be resolved using parallel transmission. In simulations and phantom experiments, the feasibility of selective excitation using nonlinear, nonbijective SEMs is demonstrated, and it is shown that the spatial resolution with which the target distribution of the transverse magnetization can be realized varies locally. Thus, the resolution of the target pattern can be increased in some regions compared with conventional linear encoding. Furthermore, experimental proof of principle of accelerated two-dimensional spatially selective excitation using nonlinear SEMs is provided in this study. PMID:23203228

  7. Characterizing the Locality of Diabatic States for Electronic Excitation Transfer by Decomposing the Diabatic Coupling

    SciTech Connect

    Vura-Weis, Josh; Newton, M. D.; Wasielewski, Michael R; Subotnik, J.E.

    2010-12-09

    A common strategy to calculate electronic coupling matrix elements for charge or energy transfer is to take the adiabatic states generated by electronic structure computations and rotate them to form localized diabatic states. In this paper, we show that, for intermolecular transfer of singlet electronic excitation, usually we cannot fully localize the electronic excitations in this way. Instead, we calculate putative initial and final states with small excitation tails caused by weak interactions with high energy excited states in the electronic manifold. These tails do not lead to substantial changes in the total diabatic coupling between states, but they do lead to a different partitioning of the total coupling between Coulomb (Förster), exchange (Dexter), and one-electron components. The tails may be reduced by using a multistate diabatic model or eliminated entirely by truncation (denoted as “chopping”). Without more information, we are unable to conclude with certainty whether the observed diabatic tails are a physical reality or a computational artifact. This research suggests that decomposition of the diabatic coupling between chromophores into Coulomb, exchange, and one-electron components may depend strongly on the number of states considered, and such results should be treated with caution.

  8. The de Broglie Wave as a Localized Excitation of the Action Function

    E-print Network

    Gregory Sivashinsky

    2010-03-12

    The Hamilton-Jacobi equation of relativistic quantum mechanics is revisited. The equation is shown to permit solutions in the form of breathers (nondispersive oscillating/spinning solitons), displaying simultaneous particle-like and wave-like behavior adaptable to the properties of the de Broglie clock. Within this formalism the de Broglie wave acquires the meaning of a localized excitation of the classical action function. The problem of quantization in terms of the breathing action function is discussed.

  9. Excitation of localized rotating waves in plasma density cavities by scattering of fast magnetosonic waves.

    PubMed

    Hall, J O; Eriksson, A I; Leyser, T B

    2004-06-25

    An analytic description of electromagnetic waves in an inhomogeneous plasma is applied to investigate excitation of localized rotating waves below the lower hybrid frequency through scattering of fast magnetosonic waves on a density cavity. The magnetosonic wave is focused to left-handed rotating oscillations. We find the amplitude of the localized oscillations, resonance frequencies, and the width of the resonances. The theory is relevant for the lower hybrid solitary structures observed in space plasmas and is shown to be consistent with observations by the Freja satellite. PMID:15245017

  10. Resonance Raman spectra of organic molecules absorbed on inorganic semiconducting surfaces: Contribution from both localized intramolecular excitation and intermolecular charge transfer excitation

    NASA Astrophysics Data System (ADS)

    Ye, ChuanXiang; Zhao, Yi; Liang, WanZhen

    2015-10-01

    The time-dependent correlation function approach for the calculations of absorption and resonance Raman spectra (RRS) of organic molecules absorbed on semiconductor surfaces [Y. Zhao and W. Z. Liang, J. Chem. Phys. 135, 044108 (2011)] is extended to include the contribution of the intermolecular charge transfer (CT) excitation from the absorbers to the semiconducting nanoparticles. The results demonstrate that the bidirectionally interfacial CT significantly modifies the spectral line shapes. Although the intermolecular CT excitation makes the absorption spectra red shift slightly, it essentially changes the relative intensities of mode-specific RRS and causes the oscillation behavior of surface enhanced Raman spectra with respect to interfacial electronic couplings. Furthermore, the constructive and destructive interferences of RRS from the localized molecular excitation and CT excitation are observed with respect to the electronic coupling and the bottom position of conductor band. The interferences are determined by both excitation pathways and bidirectionally interfacial CT.

  11. Resonance Raman spectra of organic molecules absorbed on inorganic semiconducting surfaces: Contribution from both localized intramolecular excitation and intermolecular charge transfer excitation.

    PubMed

    Ye, ChuanXiang; Zhao, Yi; Liang, WanZhen

    2015-10-21

    The time-dependent correlation function approach for the calculations of absorption and resonance Raman spectra (RRS) of organic molecules absorbed on semiconductor surfaces [Y. Zhao and W. Z. Liang, J. Chem. Phys. 135, 044108 (2011)] is extended to include the contribution of the intermolecular charge transfer (CT) excitation from the absorbers to the semiconducting nanoparticles. The results demonstrate that the bidirectionally interfacial CT significantly modifies the spectral line shapes. Although the intermolecular CT excitation makes the absorption spectra red shift slightly, it essentially changes the relative intensities of mode-specific RRS and causes the oscillation behavior of surface enhanced Raman spectra with respect to interfacial electronic couplings. Furthermore, the constructive and destructive interferences of RRS from the localized molecular excitation and CT excitation are observed with respect to the electronic coupling and the bottom position of conductor band. The interferences are determined by both excitation pathways and bidirectionally interfacial CT. PMID:26493895

  12. LES of a Jet Excited by the Localized Arc Filament Plasma Actuators

    NASA Technical Reports Server (NTRS)

    Brown, Clifford A.

    2011-01-01

    The fluid dynamics of a high-speed jet are governed by the instability waves that form in the free-shear boundary layer of the jet. Jet excitation manipulates the growth and saturation of particular instability waves to control the unsteady flow structures that characterize the energy cascade in the jet.The results may include jet noise mitigation or a reduction in the infrared signature of the jet. The Localized Arc Filament Plasma Actuators (LAFPA) have demonstrated the ability to excite a high-speed jets in laboratory experiments. Extending and optimizing this excitation technology, however, is a complex process that will require many tests and trials. Computational simulations can play an important role in understanding and optimizing this actuator technology for real-world applications. Previous research has focused on developing a suitable actuator model and coupling it with the appropriate computational fluid dynamics (CFD) methods using two-dimensional spatial flow approximations. This work is now extended to three-dimensions (3-D) in space. The actuator model is adapted to a series of discrete actuators and a 3-D LES simulation of an excited jet is run. The results are used to study the fluid dynamics near the actuator and in the jet plume.

  13. Ultrahigh Enhancement of Electromagnetic Fields by Exciting Localized with Extended Surface Plasmons

    E-print Network

    Li, Anran; Abdulhalim, Ibrahim; Li, Shuzhou

    2015-01-01

    Excitation of localized surface plasmons (LSPs) of metal nanoparticles (NPs) residing on a flat metal film has attracted great attentions recently due to the enhanced electromagnetic (EM) fields found to be higher than the case of NPs on a dielectric substrate. In the present work, it is shown that even much higher enhancement of EM fields is obtained by exciting the LSPs through extended surface plasmons (ESPs) generated at the metallic film surface using the Kretschmann-Raether configuration. We show that the largest EM field enhancement and the highest surface-enhanced fluorescence intensity are obtained when the incidence angle is the ESP resonance angle of the underlying metal film. The finite-difference time-domain simulations indicate that excitation of LSPs using ESPs can generate 1-3 orders higher EM field intensity than direct excitation of the LSPs using incidence from free space. The ultrahigh enhancement is attributed to the strong confinement of the ESP waves in the vertical direction. The drast...

  14. Localized magnetic excitation in the hybridization gap of YbAl3

    NASA Astrophysics Data System (ADS)

    Lawrence, J. M.; Goremychkin, E. A.; Bauer, E. D.

    2005-03-01

    YbAl3 is an intermediate valence (IV) compound which enters the coherent Fermi liquid phase below Tcoh = 50K.^[1] We have recently measured the magnetic scattering on the MAPS spectrometer at ISIS using high-quality single crystals. For T < 50K, the data can be fit as the sum of a background of nonmagnetic scattering and a pair of peaks at E1 = 50meV and E2 = 33meV which, in the extended zone scheme, scale with Q as the 4f form factor, as expected for magnetic scattering. The scattering near 50meV exhibits a peak in intensity near Q = (1.2, 0.5, 0.5) which also disperses somewhat with Q. Such Q-dependence is as expected for interband scattering across the hybridization gap in IV compounds. The scattering near 33meV, however, is independent of Q in both intensity and position and hence is the result of a spatially localized excitation. The energy of this excitation coincides with a deep minimum in the optical conductivity^[2], and hence the excitation energy lies in the middle of the hybridization gap. Both the magnetic excitation and the deep minimum in the conductivity gradually disappear above 50K, indicating that they are properties of the renormalized ground state. 1 A. L. Cornelius, et al, Phys. Rev. Lett. 88 (2002) 117201. 2. H. Okamura et al, Journ. Phys. Soc. Japan 73 (2004) 2045.

  15. Regular and irregular patterns of self-localized excitation in arrays of coupled phase oscillators.

    PubMed

    Wolfrum, Matthias; Omel'chenko, Oleh E; Sieber, Jan

    2015-05-01

    We study a system of phase oscillators with nonlocal coupling in a ring that supports self-organized patterns of coherence and incoherence, called chimera states. Introducing a global feedback loop, connecting the phase lag to the order parameter, we can observe chimera states also for systems with a small number of oscillators. Numerical simulations show a huge variety of regular and irregular patterns composed of localized phase slipping events of single oscillators. Using methods of classical finite dimensional chaos and bifurcation theory, we can identify the emergence of chaotic chimera states as a result of transitions to chaos via period doubling cascades, torus breakup, and intermittency. We can explain the observed phenomena by a mechanism of self-modulated excitability in a discrete excitable medium. PMID:26026325

  16. Relativistic Coulomb excitation within the time dependent superfluid local density approximation

    DOE PAGESBeta

    Stetcu, I.; Bertulani, C. A.; Bulgac, A.; Magierski, P.; Roche, K. J.

    2015-01-06

    Within the framework of the unrestricted time-dependent density functional theory, we present for the first time an analysis of the relativistic Coulomb excitation of the heavy deformed open shell nucleus 238U. The approach is based on the superfluid local density approximation formulated on a spatial lattice that can take into account coupling to the continuum, enabling self-consistent studies of superfluid dynamics of any nuclear shape. We compute the energy deposited in the target nucleus as a function of the impact parameter, finding it to be significantly larger than the estimate using the Goldhaber-Teller model. The isovector giant dipole resonance, themore »dipole pygmy resonance, and giant quadrupole modes are excited during the process. As a result, the one-body dissipation of collective dipole modes is shown to lead a damping width ???0.4 MeV and the number of preequilibrium neutrons emitted has been quantified.« less

  17. Tuning a material's properties through the excitation of localized defect modes

    NASA Astrophysics Data System (ADS)

    Serra Garcia, Marc; Lydon, Joseph; Daraio, Chiara

    2015-03-01

    Technological applications such as acoustic super-lenses and vibration mitigation devices require materials with extreme mechanical properties (Very high, zero, or negative stiffness). These properties can be achieved through buckling instabilities, local resonances and phase transitions, mechanisms that are limited to particular frequencies, strains or temperatures. In this talk I will present an alternative mechanism to tune the stiffness of a lattice. The mechanism is based on the excitation of a nonlinear localized defect mode. The oscillation of the defect mode affects the bulk properties of the lattice. This is due to the thermal expansion of the defect mode and the nonlinear coupling between the mode amplitude and the strain of the lattice. Due to the singular properties of nonlinear systems near bifurcation points, the lattice can achieve an arbitrarily large stiffness. It is possible to select point of the force-displacement relation that is being tuned by selecting the defect's excitation frequency and amplitude. Depending on the nonlinear interaction potential at the defect site, the stiffness can be tuned to extremely positive or extremely negative values. While our theoretical and experimental results have been obtained in a granular crystal, the analysis suggests that an equivalent effect should be present in other lattices with localized modes and nonlinearity.

  18. The optical theorem for local source excitation of a particle near a plane interface

    NASA Astrophysics Data System (ADS)

    Eremin, Yuri; Wriedt, Thomas

    2015-11-01

    Based on classic Maxwell's theory and the Gauss Theorem we extended the Optical Theorem to the case of a penetrable particle excited by a local source deposited near a plane interface. We demonstrate that the derived Extinction Cross-Section involves the total point source radiating cross-section and some definite integrals responsible for the scattering by the interface. The derived extinction cross-section can be employed to estimate the quantum yield and the optical antenna efficiency without computation of the absorption cross-section.

  19. Magnetic Excitations in the Nearly Localized, Itinerant Magnet Gd, Studied by Neutron Spectroscopy

    NASA Astrophysics Data System (ADS)

    Graroth, G. E.; Aczel, A. A.; Fernandez-Baca, J. A.; Nagler, S. E.

    2012-02-01

    Many of the current questions about magnetic superconductors are present when these complex materials are in the normal state. Therefore studies of simpler itinerant magnets may help provide understanding of these phenomena. We chose to study an Itinerant magnet near to the fully localized limit. The system of choice, Gd has a total moment size of ˜7.6 ?B of which ˜0.6?B of that is itinerant. We used the SEQUOIA spectrometer, at the Spallation Neutron Source at Oak Ridge National Laboratory, to measure the magnetic excitations in a 12 gm ^160Gd single crystal. The fine resolution Fermi chopper was spun at 360 Hz and phased for Ei = 50 meV. The crystal was mounted with the h0l plane horizontal and then rotated around the vertical axis in 1^o steps. This method, and the large out of plane detector coverage of SEQUOIA, provided continuous coverage of a large region of reciprocal space allowing us to map the magnetic excitations. This map provides a measured structure factor for comparison to spin wave models with and without itinerancy effects. There measurements also more clearly resolve the excitations along the h00 direction than in previous studies (J. W. Cable, R. M. Nicklow and N. Wakabayashi Phys. Rev. B 32, 1710 (1985)).

  20. The Anderson Quin Cycle

    SciTech Connect

    Anderson, J.H.; Bilbow, W.M.

    1993-03-18

    The objective of this study was to make a more refined evaluation of the Anderson Quin Cycle based on most recent information on the performance of various elements that will be used in the Anderson Quin Cycle. My original estimate of the work plan for evaluating and optimizing the Anderson Quin Cycle called for 7000 man hours of work. Since this grant was limited to 2150 man hours, we could not expect to achieve all the objectives within the allotted period of work. However, the most relevant program objectives have been completed as reported here. The analysis generally confirms the results originally estimated in my paper on the subject. (Ref. 2) Further optimizations should show even higher efficiencies. The Anderson Quin Cycle (US Patent applied for) basically consists of 5 elements in the power cycle: A refrigeration system to cool and clean the inlet air before it enters the compressor that supplies air for the gas turbine; a gas turbine consisting of a compressor, combustor, and turbine; a steam boiler and steam turbine system using the heat from the exhaust gas out of the gas turbine; a vapor turbine cycle, which utilizes the condensed heat from the exhaust of the steam turbine and the exhaust gas heat leaving the steam boiler to operate a vapor turbine cycle which utilizes another fluid than water, in this case isobutane; and the fifth element consists of a gas cooler and heat pump system, which removes the heat from the exhaust gas to lower its temperature essentially to atmospheric temperature, and at the same time permits treatment of the exhaust gas to remove acid components such as sulfur dioxide and nitrogen oxides. Current industry accepted component characteristics were incorporated in the performance analysis of the overall cycle, ensuring accurate and meaningful operating predictions. The characteristics and performance of each of the elements are described. The thermal efficiency of the optimized calculated Anderson Quin Cycle is 62 percent.

  1. Mean excitation energies for stopping powers in various materials using local plasma oscillator strengths

    NASA Technical Reports Server (NTRS)

    Wilson, J. W.; Xu, Y. J.; Kamaratos, E.; Chang, C. K.

    1984-01-01

    The basic model of Lindhard and Scharff, known as the local plasma model, is used to study the effects on stopping power of the chemical and physical state of the medium. Unlike previous work with the local plasma model, in which individual electron shifts in the plasma frequency were estimated empirically, he Pines correction derived for a degenerate Fermi gas is shown herein to provide a reasonable estimate, even on the atomic scale. Thus, the model is moved to a complete theoretical base requiring no empirical adjustments, as characteristic of past applications. The principal remaining error is in the overestimation of the low-energy absorption properties that are characteristic of the plasma model in the region of the atomic discrete spectrum, although higher-energy phenomena are accurately represented, and even excitation-to-ionization ratios are given to fair accuracy. Mean excitation energies for covalent-bonded gases and solids, for ionic gases and crystals, and for metals are calculated using first-order models of the bonded states.

  2. Prestimulus Network Integration of Auditory Cortex Predisposes Near-Threshold Perception Independently of Local Excitability.

    PubMed

    Leske, Sabine; Ruhnau, Philipp; Frey, Julia; Lithari, Chrysa; Müller, Nadia; Hartmann, Thomas; Weisz, Nathan

    2015-12-01

    An ever-increasing number of studies are pointing to the importance of network properties of the brain for understanding behavior such as conscious perception. However, with regards to the influence of prestimulus brain states on perception, this network perspective has rarely been taken. Our recent framework predicts that brain regions crucial for a conscious percept are coupled prior to stimulus arrival, forming pre-established pathways of information flow and influencing perceptual awareness. Using magnetoencephalography (MEG) and graph theoretical measures, we investigated auditory conscious perception in a near-threshold (NT) task and found strong support for this framework. Relevant auditory regions showed an increased prestimulus interhemispheric connectivity. The left auditory cortex was characterized by a hub-like behavior and an enhanced integration into the brain functional network prior to perceptual awareness. Right auditory regions were decoupled from non-auditory regions, presumably forming an integrated information processing unit with the left auditory cortex. In addition, we show for the first time for the auditory modality that local excitability, measured by decreased alpha power in the auditory cortex, increases prior to conscious percepts. Importantly, we were able to show that connectivity states seem to be largely independent from local excitability states in the context of a NT paradigm. PMID:26408799

  3. Prestimulus Network Integration of Auditory Cortex Predisposes Near-Threshold Perception Independently of Local Excitability

    PubMed Central

    Leske, Sabine; Ruhnau, Philipp; Frey, Julia; Lithari, Chrysa; Müller, Nadia; Hartmann, Thomas; Weisz, Nathan

    2015-01-01

    An ever-increasing number of studies are pointing to the importance of network properties of the brain for understanding behavior such as conscious perception. However, with regards to the influence of prestimulus brain states on perception, this network perspective has rarely been taken. Our recent framework predicts that brain regions crucial for a conscious percept are coupled prior to stimulus arrival, forming pre-established pathways of information flow and influencing perceptual awareness. Using magnetoencephalography (MEG) and graph theoretical measures, we investigated auditory conscious perception in a near-threshold (NT) task and found strong support for this framework. Relevant auditory regions showed an increased prestimulus interhemispheric connectivity. The left auditory cortex was characterized by a hub-like behavior and an enhanced integration into the brain functional network prior to perceptual awareness. Right auditory regions were decoupled from non-auditory regions, presumably forming an integrated information processing unit with the left auditory cortex. In addition, we show for the first time for the auditory modality that local excitability, measured by decreased alpha power in the auditory cortex, increases prior to conscious percepts. Importantly, we were able to show that connectivity states seem to be largely independent from local excitability states in the context of a NT paradigm. PMID:26408799

  4. Chirp- and random-based coded ultrasonic excitation for localized blood-brain barrier opening

    NASA Astrophysics Data System (ADS)

    Kamimura, H. A. S.; Wang, S.; Wu, S.-Y.; Karakatsani, M. E.; Acosta, C.; Carneiro, A. A. O.; Konofagou, E. E.

    2015-10-01

    Chirp- and random-based coded excitation methods have been proposed to reduce standing wave formation and improve focusing of transcranial ultrasound. However, no clear evidence has been shown to support the benefits of these ultrasonic excitation sequences in vivo. This study evaluates the chirp and periodic selection of random frequency (PSRF) coded-excitation methods for opening the blood-brain barrier (BBB) in mice. Three groups of mice (n??=??15) were injected with polydisperse microbubbles and sonicated in the caudate putamen using the chirp/PSRF coded (bandwidth: 1.5-1.9 MHz, peak negative pressure: 0.52?MPa, duration: 30 s) or standard ultrasound (frequency: 1.5 MHz, pressure: 0.52?MPa, burst duration: 20?ms, duration: 5?min) sequences. T1-weighted contrast-enhanced MRI scans were performed to quantitatively analyze focused ultrasound induced BBB opening. The mean opening volumes evaluated from the MRI were 9.38+/- 5.71 mm3, 8.91+/- 3.91 mm3and 35.47+/- 5.10 mm3 for the chirp, random and regular sonications, respectively. The mean cavitation levels were 55.40+/- 28.43 V.s, 63.87+/- 29.97 V.s and 356.52+/- 257.15 V.s for the chirp, random and regular sonications, respectively. The chirp and PSRF coded pulsing sequences improved the BBB opening localization by inducing lower cavitation levels and smaller opening volumes compared to results of the regular sonication technique. Larger bandwidths were associated with more focused targeting but were limited by the frequency response of the transducer, the skull attenuation and the microbubbles optimal frequency range. The coded methods could therefore facilitate highly localized drug delivery as well as benefit other transcranial ultrasound techniques that use higher pressure levels and higher precision to induce the necessary bioeffects in a brain region while avoiding damage to the surrounding healthy tissue.

  5. Thermalization and dynamics in the single-impurity Anderson model

    NASA Astrophysics Data System (ADS)

    Weymann, Ireneusz; von Delft, Jan; Weichselbaum, Andreas

    2015-10-01

    We analyze the process of thermalization, dynamics, and the eigenstate thermalization hypothesis (ETH) for the single-impurity Anderson model, focusing on the Kondo regime. For this we construct the complete eigenbasis of the Hamiltonian using the numerical renormalization group (NRG) method in the language of the matrix product states. It is a peculiarity of the NRG that while the Wilson chain is supposed to describe a macroscopic bath, very few single-particle excitations already suffice to essentially thermalize the impurity system at finite temperature, which amounts to having added a macroscopic amount of energy. Thus, given an initial state of the system such as the ground state together with microscopic excitations, we calculate the spectral function of the quantum impurity using the microcanonical and diagonal ensembles. These spectral functions are compared to the time-averaged spectral function obtained by time evolving the initial state according to the full Hamiltonian, and to the spectral function calculated using the thermal density matrix. By adding or removing particles at a certain Wilson energy shell on top of the ground state, we find qualitative agreement between the resulting spectral functions calculated for different ensembles. This indicates that the system thermalizes in the long-time limit, and can be described by an appropriate statistical-mechanical ensemble. Moreover, by calculating static quantities such as the impurity spectral density at the Fermi level as well as the dot occupancy for energy eigenstates relevant for microcanonical ensemble, we find good support for the ETH. The ultimate mechanism responsible for this effective thermalization within the NRG can be identified as Anderson orthogonality: the more charge that needs to flow to or from infinity after applying a local excitation within the Wilson chain, the more the system looks thermal afterwards at an increased temperature. For the same reason, however, thermalization fails if charge rearrangement after the excitation remains mostly local. In these cases, the different statistical ensembles lead to different results. Their behavior needs to be understood as a microscopic quantum quench only.

  6. How Local Excitation–Inhibition Ratio Impacts the Whole Brain Dynamics

    PubMed Central

    Deco, Gustavo; Hagmann, Patric; Romani, Gian Luca; Mantini, Dante; Corbetta, Maurizio

    2014-01-01

    The spontaneous activity of the brain shows different features at different scales. On one hand, neuroimaging studies show that long-range correlations are highly structured in spatiotemporal patterns, known as resting-state networks, on the other hand, neurophysiological reports show that short-range correlations between neighboring neurons are low, despite a large amount of shared presynaptic inputs. Different dynamical mechanisms of local decorrelation have been proposed, among which is feedback inhibition. Here, we investigated the effect of locally regulating the feedback inhibition on the global dynamics of a large-scale brain model, in which the long-range connections are given by diffusion imaging data of human subjects. We used simulations and analytical methods to show that locally constraining the feedback inhibition to compensate for the excess of long-range excitatory connectivity, to preserve the asynchronous state, crucially changes the characteristics of the emergent resting and evoked activity. First, it significantly improves the model's prediction of the empirical human functional connectivity. Second, relaxing this constraint leads to an unrealistic network evoked activity, with systematic coactivation of cortical areas which are components of the default-mode network, whereas regulation of feedback inhibition prevents this. Finally, information theoretic analysis shows that regulation of the local feedback inhibition increases both the entropy and the Fisher information of the network evoked responses. Hence, it enhances the information capacity and the discrimination accuracy of the global network. In conclusion, the local excitation–inhibition ratio impacts the structure of the spontaneous activity and the information transmission at the large-scale brain level. PMID:24899711

  7. Locally-excited (LE) versus charge-transfer (CT) excited state competition in a series of para-substituted neutral green fluorescent protein (GFP) chromophore models.

    PubMed

    Olsen, Seth

    2015-02-12

    In this paper, I provide a characterization of the low-energy electronic structure of a series of para-substituted neutral green fluorescent protein (GFP) chromophore models using a theoretical approach that blends linear free energy relationships (LFERs) with state-averaged complete-active-space self-consistent field (SA-CASSCF) theory. The substituents are chosen to sample the Hammett ?(p) scale from R = F to NH2, and a model of the neutral GFP chromophore structure (R = OH) is included. I analyze the electronic structure for different members of the series in a common complete-active-space valence-bond (CASVB) representation, exploiting an isolobal analogy between active-space orbitals for different members of the series. I find that the electronic structure of the lowest adiabatic excited state is a strong mixture of weakly coupled states with charge-transfer (CT) or locally excited (LE) character and that the dominant character changes as the series is traversed. Chromophores with strongly electron-donating substituents have a CT-like excited state such as expected for a push-pull polyene or asymmetric cyanine. Chromophores with weakly electron-donating (or electron-withdrawing) substituents have an LE-like excited state with an ionic biradicaloid structure localized to the ground-state bridge ? bond. PMID:25343562

  8. Localization of magnetic and electronic excitations in nanotubes with line defects

    NASA Astrophysics Data System (ADS)

    Komorowski, P. G.; Cottam, M. G.

    2015-03-01

    A matrix Green's function formalism is employed to study the excitations in long nanotubes where the dynamics are governed by nearest-neighbor interactions between atoms. Examples of the excitations, which can be characterized in terms of the tube circumference and a one-dimensional wave number along the length, include ferromagnetic spin waves in a Heisenberg exchange model and electronic modes in a tight-binding model with hopping. It is assumed that the system is a single-walled nanotube of negligible thickness and that the atoms are arranged on a simple square lattice. Defects in the form of substitutional impurity atoms are introduced to study localized modes as well as the propagating modes of the pure (host) material. The impurities have the form of one or more line defects parallel to the nanotube axis. The derived Green's functions provide a description of the frequencies of the discrete modes of the system and their spectral intensities. Numerical examples are presented for different mode types (magnetic and electronic), nanotube diameters and arrangements of impurity lines.

  9. Localized Excitation in the Hybridization Gap in YbAl{sub 3}

    SciTech Connect

    Christianson, A.D.; Fanelli, V.R.; Lawrence, J.M.; Goremychkin, E.A.; Osborn, R.; Bauer, E.D.; Sarrao, J.L.; Thompson, J.D.; Frost, C.D.; Zarestky, J. L.

    2006-03-24

    The intermediate valence compound YbAl{sub 3} exhibits a broad magnetic excitation in the inelastic neutron scattering spectrum with characteristic energy E{sub 1}{approx_equal}50 meV, equal to the Kondo energy (T{sub K}{approx}600-700 K). In the low temperature (Tlocalized excitation in the hybridization gap.

  10. Response of bare 1-3 piezocomposite array to localized electrical excitation.

    PubMed

    Guyonvarch, Jérôme; Certon, Dominique; Ratsimandresy, Leong; Patat, Frédéric; Lethiecq, Marc

    2005-01-01

    The theoretical response of a 1-3 piezocomposite plate submitted to localized electrical excitation was studied with the theory of guided waves. The theoretical modeling was based on the global matrix method, and the piezocomposite material was considered as a homogeneous medium. To validate the theoretical results, experimental displacement measurements were performed with an interferometric probe on two piezocomposite plates, one with a single element and one with an array of electrodes. The measured response on the single-element plate was mainly supported by the S0 and S3 modes of the plate. Homogenization limits of the composite in terms of frequency and wave number are defined on the basis of data from this sample. Within these limits, the piezocomposite material operates as a homogeneous medium, and comparison between theoretical and experimental results allows the equivalent electroacoustic parameters to be evaluated. A second sample was measured to study the effects of the electrode array on the electroacoustic response of the plate. Two kinds of electrical excitation were studied. PMID:15704413

  11. High spectral specificity of local chemical components characterization with multichannel shift-excitation Raman spectroscopy

    NASA Astrophysics Data System (ADS)

    Chen, Kun; Wu, Tao; Wei, Haoyun; Wu, Xuejian; Li, Yan

    2015-09-01

    Raman spectroscopy has emerged as a promising tool for its noninvasive and nondestructive characterization of local chemical structures. However, spectrally overlapping components prevent the specific identification of hyperfine molecular information of different substances, because of limitations in the spectral resolving power. The challenge is to find a way of preserving scattered photons and retrieving hidden/buried Raman signatures to take full advantage of its chemical specificity. Here, we demonstrate a multichannel acquisition framework based on shift-excitation and slit-modulation, followed by mathematical post-processing, which enables a significant improvement in the spectral specificity of Raman characterization. The present technique, termed shift-excitation blind super-resolution Raman spectroscopy (SEBSR), uses multiple degraded spectra to beat the dispersion-loss trade-off and facilitate high-resolution applications. It overcomes a fundamental problem that has previously plagued high-resolution Raman spectroscopy: fine spectral resolution requires large dispersion, which is accompanied by extreme optical loss. Applicability is demonstrated by the perfect recovery of fine structure of the C-Cl bending mode as well as the clear discrimination of different polymorphs of mannitol. Due to its enhanced discrimination capability, this method offers a feasible route at encouraging a broader range of applications in analytical chemistry, materials and biomedicine.

  12. High spectral specificity of local chemical components characterization with multichannel shift-excitation Raman spectroscopy

    PubMed Central

    Chen, Kun; Wu, Tao; Wei, Haoyun; Wu, Xuejian; Li, Yan

    2015-01-01

    Raman spectroscopy has emerged as a promising tool for its noninvasive and nondestructive characterization of local chemical structures. However, spectrally overlapping components prevent the specific identification of hyperfine molecular information of different substances, because of limitations in the spectral resolving power. The challenge is to find a way of preserving scattered photons and retrieving hidden/buried Raman signatures to take full advantage of its chemical specificity. Here, we demonstrate a multichannel acquisition framework based on shift-excitation and slit-modulation, followed by mathematical post-processing, which enables a significant improvement in the spectral specificity of Raman characterization. The present technique, termed shift-excitation blind super-resolution Raman spectroscopy (SEBSR), uses multiple degraded spectra to beat the dispersion-loss trade-off and facilitate high-resolution applications. It overcomes a fundamental problem that has previously plagued high-resolution Raman spectroscopy: fine spectral resolution requires large dispersion, which is accompanied by extreme optical loss. Applicability is demonstrated by the perfect recovery of fine structure of the C-Cl bending mode as well as the clear discrimination of different polymorphs of mannitol. Due to its enhanced discrimination capability, this method offers a feasible route at encouraging a broader range of applications in analytical chemistry, materials and biomedicine. PMID:26350355

  13. Spoof localized surface plasmons in corrugated ring structures excited by microstrip line.

    PubMed

    Yang, Bao Jia; Zhou, Yong Jin; Xiao, Qian Xun

    2015-08-10

    We have investigated the fundamental and high-order spoof localized surface plasmons (LSPs) modes in the proposed corrugated ring resonator printed on a thin dielectric substrate with or without ground plane. An efficient and ease-of-integration method to excite spoof LSPs in the textured ring resonator has been adopted to suppress unwanted high-order modes and enhance fundamental modes. A multi-band-pass filter has been proposed and numerically demonstrated. Experimental results at the microwave frequencies verify the high performances of the corrugated ring resonator and the filter, showing great agreements with the simulation results. We have also shown that the fabricated device is sensitive to the variation of the refraction index of materials under test, even when the material is as thin as paper. PMID:26367991

  14. Localization of singlet excitation in short silicon chains, Si 2Me 6 to Si 6Me 14

    NASA Astrophysics Data System (ADS)

    Plitt, Harald S.; Balaji, V.; Michl, Josef

    1993-10-01

    In argon matrix isolation, permethylated linear oligosilanes with six or fewer silicon atoms in the chain exhibit nearly identical broad strongly Stokes-shifted fluorescence. As the chain becomes shorter, the emission becomes weaker and its peak red-shifts slightly. We propose that the emission is due to a non-vertical excited state with a single greatly stretched SiSi bond, in which the excitation is localized, and support the proposal by ab initio calculations on Si 2H 6.

  15. Localization and dynamics of long-lived excitations in colloidal semiconductor nanocrystals with dual quantum confinement.

    PubMed

    Liu, Su; Borys, Nicholas J; Sapra, Sameer; Eychmüller, Alexander; Lupton, John M

    2015-06-01

    Semiconductor nanocrystals consisting of a quantum dot (QD) core and a quantum well (QW) shell, where the QD and QW are separated by a tunneling barrier, offer a unique opportunity to engineer the photophysical properties of individual nanostructures. Using the thicknesses of the corresponding layers, the excitons of the first and second excited states can be separated spatially, localizing one state to the QD and the other to the QW. Thus the wave function overlap of the two states can be minimized, suppressing non-radiative thermalization between the two wells, which in turn leads to radiative relaxation from both states. The molecular analogy to such dual emission would be the inhibition of internal conversion, a special case that violates Kasha's rule. Using nanosecond time-resolved spectroscopy of QDQW CdSe/ZnS onion-like nanocrystals, an intermediate regime of exciton separation and suppressed thermalization is identified where the non-radiative relaxation of the higher-energy state is slowed, but not completely inhibited. In this intermediate thermalization regime, the temporal evolution of the delayed emission spectra resulting from trapped carriers mimic the dynamics of such states in nanocrystals that consist of only a QD core. In stark contrast, when a higher-energy metastable state exists in the QW shell due to strongly suppressed interwell thermalization, the spectral dynamics of the long-lived excitations in the QD and QW, which are spectrally distinct, are amplified and differ from each other as well as from those in the core-only nanocrystals. This difference in spectral dynamics demonstrates the utility of exploiting well-defined exciton localization to study the nature and spatial dependence of the intriguing photophysics of colloidal semiconductor nanocrystals, and illustrates the power of nanosecond gated luminescence spectroscopy in illuminating complex relaxation dynamics which are entirely masked in steady-state or ultrafast spectroscopy. PMID:25807918

  16. 1 UCLA ANDERSON EMBA UCLA ANDERSON SCHOOL OF MANAGEMENT

    E-print Network

    Palsberg, Jens

    32 UCLA ANDERSON EMBA UCLA ANDERSON EMBA 3 International Residency Program: China China's global, economy and business culture is essential. What better solution than immersion? Our China Residency, Chinese and Islamic Economies International Exchange Programs EMBA students can take one-week elective

  17. Local-field excitations in two-dimensional lattices of resonant atoms

    SciTech Connect

    Volkov, S. N.; Kaplan, A. E.

    2010-04-15

    We study excitations of the local field (locsitons) in nanoscale two-dimensional (2D) lattices of strongly interacting resonant atoms and various unusual effects associated with them. Locsitons in low-dimensional systems and the resulting spatial strata and more complex patterns on a scale of just a few atoms were predicted by us earlier [A. E. Kaplan and S. N. Volkov, Phys. Rev. Lett. 101, 133902 (2008)]. These effects present a radical departure from the classical Lorentz-Lorenz theory of the local field (LF), which assumes that the LF is virtually uniform on this scale. We demonstrate that the strata and patterns in the 2D lattices may be described as an interference of plane-wave locsitons, build an analytic model for such unbounded locsitons, and derive and analyze dispersion relations for the locsitons in an equilateral triangular lattice. We draw useful analogies between 1D and 2D locsitons but also show that the 2D case enables locsitons with the most diverse and unusual properties. Using the nearest-neighbor approximation, we find the locsiton frequency band for different mutual orientations of the lattice and the incident field. We demonstrate a formation of distinct vector locsiton patterns consisting of multiple vortices in the LF distribution and suggest a way to design finite 2D lattices that exhibit such patterns at certain frequencies. We illustrate the role of lattice defects in supporting localized locsitons and also demonstrate the existence of 'magic shapes', for which the LF suppression at the exact atomic resonance is canceled.

  18. Tunable local excitation of surface plasmon polaritons by sum-frequency generation in ZnO nanowires

    NASA Astrophysics Data System (ADS)

    Brincker, Mads; Pedersen, Kjeld; Skovsen, Esben

    2015-12-01

    Tunable local excitation of surface plasmon polaritons (SPP) by sum-frequency generation (SFG) in Zinc Oxide (ZnO) nanowires on a smooth and thin silver film has been studied by applying angle resolved leakage radiation spectroscopy. SFG between an infrared (IR) source, with a variable wavelength in the telecom range between 1350 nm and 1550 nm, and a near-infrared (NIR) source with a fixed wavelength of 790 nm resulted in the excitation of SPP's at wavelengths between 498 nm and 523 nm. The SFG to SPP coupling efficiency was studied as a function of the excitation angle and the wavelength of the IR source. It was shown that the SPP coupling was most efficient at oblique excitation angles, and that SFG in ZnO nanowires allows for the coherent conversion of optical signals at telecom frequencies to SPP's with frequencies within the visible range.

  19. Transition from charge-transfer to largely locally excited exciplexes, from structureless to vibrationally structured emissions.

    PubMed

    Young, Ralph H; Feinberg, Adam M; Dinnocenzo, Joseph P; Farid, Samir

    2015-01-01

    Exciplexes of 9,10-dicyanoanthracene (DCA) with alkylbenzene donors in cyclohexane show structureless emission spectra, typical of exciplexes with predominantly charge-transfer (CT) character, when the donor has a relatively low oxidation potential (Eox ), e.g. hexamethylbenzene (HMB). With increasing Eox and stronger mixing with a locally excited (LE) state, vibrational structure begins to appear with 1,2,3,5-tetramethylbenzene and becomes prominent with p-xylene (p-Xy). A simple theoretical model reproduces the spectra and the radiative rate constants, and it reveals several surprises: Even in this nonpolar solvent, the fractional CT character of a highly mixed exciplex varies widely in response to fluctuations in the microscopic environment. Environments that favor the LE (or CT) state contribute more to the blue (or red) side of the overall spectrum. It is known that sparsely substituted benzene radical cations, e.g., p-Xy(•+) , are stabilized more in acetonitrile than the heavily substituted HMB(•+) . Remarkably, ion pairing with DCA(•-) in cyclohexane leads to even larger differences in the stabilization of these radical cations. The spectra of the low-Eox donors are almost identical except for displacements that approximately equal the differences in Eox , even though the exciplexes have varying degrees of CT character. These similarities result from compensation among several nonobvious, but quantified factors. PMID:25363042

  20. Anderson's Orthogonality Catastrophe

    NASA Astrophysics Data System (ADS)

    Gebert, Martin; Küttler, Heinrich; Müller, Peter

    2014-08-01

    We give an upper bound on the modulus of the ground-state overlap of two non-interacting fermionic quantum systems with N particles in a large but finite volume L d of d-dimensional Euclidean space. The underlying one-particle Hamiltonians of the two systems are standard Schrödinger operators that differ by a non-negative compactly supported scalar potential. In the thermodynamic limit, the bound exhibits an asymptotic power-law decay in the system size L, showing that the ground-state overlap vanishes for macroscopic systems. The decay exponent can be interpreted in terms of the total scattering cross section averaged over all incident directions. The result confirms and generalises P. W. Anderson's informal computation (Phys. Rev. Lett. 18:1049-1051, 1967).

  1. Observation of Infinite-Range Intensity Correlations above, at, and below the Mobility Edges of the 3D Anderson Localization Transition

    E-print Network

    Page, John

    Observation of Infinite-Range Intensity Correlations above, at, and below the Mobility Edges. Our ultrasonic experiments are designed to unambig- uously detect a recently predicted infinite the transition between diffuse and localized behavior occurs. Moreover, a new type of infinite-range intensity

  2. Characterizing the Locality of Diabatic States forElectronic Excitation Transfer By Decomposing theDiabatic Coupling

    SciTech Connect

    Newton, M.D.; Vura-Weis, J.; Wasielewski, M.R.; Subotnik, J.E.

    2010-10-19

    A common strategy to calculate electronic coupling matrix elements for charge or energy transfer is to take the adiabatic states generated by electronic structure computations and rotate them to form localized diabatic states. In this paper, we show that, for intermolecular transfer of singlet electronic excitation, usually we cannot fully localize the electronic excitations in this way. Instead, we calculate putative initial and final states with small excitation tails caused by weak interactions with high energy excited states in the electronic manifold. These tails do not lead to substantial changes in the total diabatic coupling between states, but they do lead to a different partitioning of the total coupling between Coulomb (Forster), exchange (Dexter), and one-electron components. The tails may be reduced by using a multistate diabatic model or eliminated entirely by truncation (denoted as 'chopping'). Without more information, we are unable to conclude with certainty whether the observed diabatic tails are a physical reality or a computational artifact. This research suggests that decomposition of the diabatic coupling between chromophores into Coulomb, exchange, and one-electron components may depend strongly on the number of states considered, and such results should be treated with caution.

  3. Anderson transition for Google matrix eigenstates

    NASA Astrophysics Data System (ADS)

    Zhirov, O. V.; Shepelyansky, D. L.

    2015-10-01

    We introduce a number of random matrix models describing the Google matrix G of directed networks. The properties of their spectra and eigenstates are analyzed by numerical matrix diagonalization. We show that for certain models it is possible to have an algebraic decay of PageRank vector with the exponent similar to real directed networks. At the same time the spectrum has no spectral gap and a broad distribution of eigenvalues in the complex plain. The eigenstates of G are characterized by the Anderson transition from localized to delocalized states and a mobility edge curve in the complex plane of eigenvalues.

  4. Anderson transition for Google matrix eigenstates

    E-print Network

    Zhirov, O V

    2015-01-01

    We introduce a number of random matrix models describing the Google matrix G of directed networks. The properties of their spectra and eigenstates are analyzed by numerical matrix diagonalization. We show that for certain models it is possible to have an algebraic decay of PageRank vector with the exponent similar to real directed networks. At the same time the spectrum has no spectral gap and a broad distribution of eigenvalues in the complex plain. The eigenstates of G are characterized by the Anderson transition from localized to delocalized states and a mobility edge curve in the complex plane of eigenvalues.

  5. Describing excited state relaxation and localization in TiO2 nanoparticles using TD-DFT

    DOE PAGESBeta

    Berardo, Enrico; Hu, Han -Shi; van Dam, Hubertus J. J.; Shevlin, Stephen A.; Woodley, Scott M.; Kowalski, Karol; Zwijnenburg, Martijn A.

    2014-02-26

    We have investigated the description of excited state relaxation in naked and hydrated TiO2 nanoparticles using Time-Dependent Density Functional Theory (TD-DFT) with three common hybrid exchange-correlation (XC) potentials; B3LYP, CAM-B3LYP and BHLYP. Use of TD-CAM-B3LYP and TD-BHLYP yields qualitatively similar results for all structures, which are also consistent with predictions of coupled cluster theory for small particles. TD-B3LYP, in contrast, is found to make rather different predictions; including apparent conical intersections for certain particles that are not observed with TD-CAM-B3LYP nor with TD-BHLYP. In line with our previous observations for vertical excitations, the issue with TD-B3LYP appears to be themore »inherent tendency of TD-B3LYP, and other XC potentials with no or a low percentage of Hartree-Fock Like Exchange, to spuriously stabilize the energy of charge-transfer (CT) states. Even in the case of hydrated particles, for which vertical excitations are generally well described with all XC potentials, the use of TD-B3LYP appears to result in CT-problems for certain particles. We hypothesize that the spurious stabilization of CT-states by TD-B3LYP even may drive the excited state optimizations to different excited state geometries than those obtained using TD-CAM-B3LYP or TD-BHLYP. In conclusion, focusing on the TD-CAM-B3LYP and TD-BHLYP results, excited state relaxation in naked and hydrated TiO2 nanoparticles is predicted to be associated with a large Stokes’ shift.« less

  6. Boson localization and excitations of liquid 4 He confined in gelsil

    E-print Network

    Glyde, Henry R.

    neutron scattering measurements of the phonon-roton P-R modes of liquid 4 He at saturated vapor pressure confined in 44 Å mean pore diameter gelsil in the wave vector range 0.4 Q 2.15 Å-1 . Layer modes, modes comparisons with predictions. In contrast, mea- surement of the excitations of liquid 4 He in porous media has

  7. Conservation genetics of a rare Gerbil species: a comparison of the population genetic structures and demographic histories of the locally rare Pygmy Gerbil and the common Anderson's Gerbil

    PubMed Central

    2010-01-01

    Background One of the major challenges in evolutionary biology is identifying rare species and devising management plans to protect them while also sustaining their genetic diversity. However, in attempting a broad understanding of rarity, single-species studies provide limited insights because they do not reveal whether the factors that affect rare species differ from those that affect more common species. To illustrate this important concept and to arrive at a better understanding of the form of rarity characterizing the rare Gerbillus henleyi, we explored its population genetic structure alongside that of the locally common Gerbillus andersoni allenbyi. We trapped gerbils in several locations in Israel's western and inner Negev sand dunes. We then extracted DNA from ear samples, and amplified two mitochondrial sequences: the control region (CR) and the cytochrome oxidase 2 gene (CO2). Results Nucleotide diversity was low for all sequences, especially for the CR of G. a. allenbyi, which showed no diversity. We could not detect any significant population genetic structure in G. henleyi. In contrast, G. a. allenbyi's CO2 sequence showed significant population genetic structure. Pairwise PhiPT comparisons showed low values for G. henleyi but high values for G. a. allenbyi. Analysis of the species' demographic history indicated that G. henleyi's population size has not changed recently, and is under the influence of an ongoing bottleneck. The same analysis for G. a. allenbyi showed that this species has undergone a recent population expansion. Conclusions Comparing the two species, the populations of G. a. allenbyi are more isolated from each other, likely due to the high habitat specificity characterizing this species. The bottleneck pattern found in G. henleyi may be the result of competition with larger gerbil species. This result, together with the broad habitat use and high turnover rate characterizing G. henleyi, may explain the low level of differentiation among its populations. The evidence for a recent population expansion of G. a. allenbyi fits well with known geomorphological data about the formation of the Negev sand dunes and paleontological data about this species' expansion throughout the Levant. In conclusion, we suggest that adopting a comparative approach as presented here can markedly improve our understanding of the causes and effects of rarity, which in turn can allow us to better protect biodiversity patterns. PMID:20525191

  8. Superdiffusive Transport and Energy Localization in Disordered Granular Crystals

    E-print Network

    Alejandro J. Martínez; P. G. Kevrekidis; Mason A. Porter

    2015-09-11

    We study the spreading of initially localized excitations in 1D disordered granular crystals. We thereby investigate localization phenomena in strongly nonlinear systems, which we demonstrate to be fundamentally different from localization in linear and weakly nonlinear systems. We compare wave dynamics in chains with 3 different types of disorder: an uncorrelated (Anderson-like) disorder and 2 types of correlated disorders (random dimer arrangements), and for 2 types of initial conditions: displacement excitations and velocity excitations. For strongly precompressed chains, the dynamics depend strongly on the initial condition. For displacement excitations, the long-time behavior of the second moment $\\tilde{m}_2$ has oscillations that depend on the type of disorder, with a complex trend that differs markedly from a power law and which is particularly evident for an Anderson disorder. For velocity excitations, we find a scaling $\\tilde{m}_2\\sim t^{\\gamma}$ (for a constant $\\gamma$) for all 3 types of disorder. For weakly precompressed (strongly nonlinear) chains, $\\tilde{m}_2$ and the inverse participation ratio $P^{-1}$ satisfy $\\tilde{m}_2\\sim t^{\\gamma}$ and $P^{-1}\\sim t^{-\\eta}$, and the dynamics is superdiffusive for all examined cases. When precompression is strong, the IPR decreases slowly for all 3 types of disorder, and we observe a partial localization around the core and the leading edge of the wave. For an Anderson disorder, displacement perturbations lead to localization of energy primarily in the core, and velocity perturbations cause the energy to be divided between the core and the leading edge. This localization phenomenon does not occur in the sonic-vacuum regime, which yields the surprising result that the energy is no longer contained in strongly nonlinear waves but instead is spread across many sites. In this regime, the exponents are very similar in all cases.

  9. Local conformations and excited state dynamics of porphyrins and nucleic acids by 2-dimensional fluorescence spectroscopy

    NASA Astrophysics Data System (ADS)

    Widom, Julia R.

    Biological systems present many challenges to researchers attempting to study them using spectroscopy. Low specificity, low sensitivity, and broad and overlapping lineshapes limit the amount of information that can be obtained in experiments. Two-dimensional fluorescence spectroscopy (2D FS) is a highly sensitive and information-rich spectroscopic technique that was developed to study the conformations and excited state dynamics of systems exhibiting exciton coupling. In this dissertation, I describe a variety of extensions of 2D FS that further increase its utility for the study of biological systems. I describe experiments on a dimer of zinc tetraphenylporphyrin embedded in a membrane, in which the signals from two conformational subpopulations were separated in order to study the thermodynamics of their interconversion. I present proof-of-principle experiments on nucleic acids that utilize fluorescence resonance energy transfer to separate signals from different subpopulations. I also describe experiments in which 2D FS was performed using ultraviolet excitation to determine the conformation of a dinucleotide of a fluorescent analogue of the nucleic acid base adenine. I discuss experiments on porphyrin dimers in which 2D FS was used as a probe of excited state dynamics. Finally, I present model calculations for a proposed variation of 2D FS in which entangled photons would be used as the excitation source. These calculations suggest that this approach has the potential to yield significantly narrower spectral lineshapes than conventional 2D FS. These experiments and calculations yield new insight into the systems investigated and establish a `toolbox' of variations of 2D FS that can be used to gain as much information as possible from experiments on challenging systems such as protein-DNA complexes.

  10. Local Investigation in Dynamic Behavior of Excited Water Nanoclusters on Cu(111) Surface

    NASA Astrophysics Data System (ADS)

    Guo, Yang; Gong, Huiqi; Dong, Li; Li, Lailai; Wang, Jinchuan; Shan, Xinyan; Lu, Xinghua

    2014-03-01

    Dynamic behavior of water molecules on surfaces is important for surface-mediated water dissociations and reactions. Here we present investigations in dynamic behavior of excited water nanoclusters on Cu (111) surface by using a low temperature scanning tunneling microscope (STM). It is found that excess electrons in a single water nanocluster can be injected from a metallic STM tip under a positive voltage. Such injection of electrons results in both the diffusion of single H2O molecules within the nanocluster and directional diffusion of water nanoclusters on surface. The range of lateral diffusion is limited to several nanometers from the tip because of the electrical screening effect from Cu substrate for the excess electrons in the nanocluster. In addition, femto-second laser pulses are employed to excite the water nanoclusters during STM imaging with tip in the tunneling condition. Significant changes in topographic profile of H2O nanoclusters are observed under the photoexciation, as compared with that of the nanoclusters in the ground state. The results obtained in this study provide a microscopic understanding of the diffusion mechanism of excited water nanoclusters on surface. the National Science Foundation of China (Grant No. 11174347, 61376100) and the Ministry of Science and Technology of China (Grant No. 2012CB933002).

  11. Localized electronic excitations in NiO studied with resonant inelastic X-Ray scattering at the Ni M threshold: evidence of spin flip.

    PubMed

    Chiuzb?ian, S G; Ghiringhelli, G; Dallera, C; Grioni, M; Amann, P; Wang, X; Braicovich, L; Patthey, L

    2005-11-01

    We studied the neutral electronic excitations of NiO localized at the Ni sites by measuring the resonant inelastic x-ray scattering (RIXS) spectra at the Ni M2,3 edges. The good energy resolution allows an unambiguous identification of several spectral features due to excitations. The dependence of the RIXS spectra on the excitation energy gives evidence of local spin flip and yields a value of 125 +/- 15 meV for the antiferromagnetic exchange interaction. Accurate crystal field parameters are also obtained. PMID:16384022

  12. 2014 Integrated Scholar: Todd Anderson

    E-print Network

    Rock, Chris

    in Home Texas Tech Today Media Resources News Experts Guide Emergency Communications TTYou Social Media/06/2014-integrated-scholar-todd-anderson/[6/6/2014 12:05:26 PM] TTU Home Communications & Marketing Home Texas Tech. Texas Tech Today Resources Communications & Marketing Resources Texas Tech University Home RSS Feeds

  13. M D Anderson Cancer Center

    Cancer.gov

    This proposal will establish a Small Animal Imaging Research Program (SAIRP) at The University of Texas M. D. Anderson Cancer Center. The proposed SAIRP will complement the existing institutional facility that provides small animal imaging services to NIH funded investigators. The broad goal of this SAIRP is to develop novel imaging approaches to solve cancer related biological questions and evaluate new cancer therapies.

  14. Solvent effects on the optical spectra and excited-state decay of triphenylamine-thiadiazole with hybridized local excitation and intramolecular charge transfer.

    PubMed

    Fan, Di; Yi, Yuanping; Li, Zhendong; Liu, Wenjian; Peng, Qian; Shuai, Zhigang

    2015-05-28

    The triphenylamine-thiadiazole molecule (TPA-NZP) is a newly popular, highly efficient OLED fluorescent emitter with exciton utilization efficiency exceeding the upper limit of spin statistics (25%). In this work, the optical spectra and the radiative and nonradiative decay rate constants have been investigated theoretically for TPA-NZP in hexane, ethyl ether, tetrahydrofuran, and dimethylformamide solvents, in comparison with the gas phase. We observed the evolutions of the excited states from the hybridized local and charge-transfer (HLCT) character to complete intramolecular charge transfer (CT) character with the increase of the solvent polarities. It is found that upon increasing the solvent polarity, the amount of red shift in the absorption peak is much less than that of emission, resulting in breakdown of the mirror symmetry. This is because that 0-0 transition energy is red-shifted but the vibrational relaxation increases with the solvent polarity, leading to subtraction in absorption while addition in emission. The radiative decay rate constant is calculated to be almost independent of polarity. The nonradiative decay rate increases by almost one order of magnitude from that in nonpolar hexane to the strongly polarized dimethylformamide, which is attributed to the dual effects of the red shift in the gap and enhancement of the vibrational relaxation by solvent polarity. PMID:25402947

  15. Predicting Accurate Electronic Excitation Transfer Rates via Marcus Theory with Boys or Edmiston-Ruedenberg Localized Diabatization

    SciTech Connect

    Subotnik, Joseph E.; Vura-Weis, Josh; Sodt, Alex J.; Ratner, Mark A.

    2010-05-06

    We model the triplet-triplet energy-transfer experiments from the Closs group [Closs, G. L.; et al. J. Am. Chem. Soc. 1988, 110, 2652.] using a combination of Marcus theory and either Boys or Edmiston-Ruedenberg localized diabatization, and we show that relative and absolute rates of electronic excitation transfer may be computed successfully. For the case where both the donor and acceptor occupy equatorial positions on a rigid cyclohexane bridge, we find ?calc = 2.8 per C-C bond, compared with the experimental value ?exp = 2.6. This work highlights the power of using localized diabatization methods as a tool for modeling nonequilibrium processes.

  16. Probing exciton localization/delocalization: transient dc photoconductivity studies of excited states of symmetrical porphyrin monomers, oligomers, and supramolecular assemblies.

    PubMed

    She, Chunxing; McGarrah, James E; Lee, Suk Joong; Goodman, Joshua L; Nguyen, SonBinh T; Williams, J A G; Hupp, Joseph T

    2009-07-23

    Solution-phase transient dc photoconductivity (TDCP) measurements are used to address the question of exciton localization/delocalization in strongly coupled oligomeric porphyrins and in well-defined, higher-order assemblies of oligomers (ladder and prism assemblies). The approach used is determination of the excited-state excess polarizability volume, Delta alpha(V)--a quantity known to report on exciton delocalization. The measurements reveal for the oligomers that singlet excitons are substantially delocalized but that triplet excitons are much more localized. For each of the two higher-order assemblies, the measurements reveal that excitons are transiently confined to individual oligomeric subunits rather than being delocalized over the entire assembly. PMID:19569676

  17. The cortical innate immune response increases local neuronal excitability leading to seizures

    PubMed Central

    Rodgers, Krista M.; Hutchinson, Mark R.; Northcutt, Alexis; Maier, Steven F.; Watkins, Linda R.

    2009-01-01

    Brain glial cells, five times more prevalent than neurons, have recently received attention for their potential involvement in epileptic seizures. Microglia and astrocytes, associated with inflammatory innate immune responses, are responsible for surveillance of brain damage that frequently results in seizures. Thus, an intriguing suggestion has been put forward that seizures may be facilitated and perhaps triggered by brain immune responses. Indeed, recent evidence strongly implicates innate immune responses in lowering seizure threshold in experimental models of epilepsy, yet, there is no proof that they can play an independent role in initiating seizures in vivo. Here, we show that cortical innate immune responses alone produce profound increases of brain excitability resulting in focal seizures. We found that cortical application of lipopolysaccharide, binding to toll-like receptor 4 (TLR4), triples evoked field potential amplitudes and produces focal epileptiform discharges. These effects are prevented by pre-application of interleukin-1 receptor antagonist. Our results demonstrate how the innate immune response may participate in acute seizures, increasing neuronal excitability through interleukin-1 release in response to TLR4 detection of the danger signals associated with infections of the central nervous system and with brain injury. These results suggest an important role of innate immunity in epileptogenesis and focus on glial inhibition, through pharmacological blockade of TLR4 and the pro-inflammatory mediators released by activated glia, in the study and treatment of seizure disorders in humans. PMID:19567702

  18. Spatial dispersion effects upon local excitation of extrinsic plasmons in a graphene micro-disk

    NASA Astrophysics Data System (ADS)

    Mencarelli, D.; Bellucci, S.; Sindona, A.; Pierantoni, L.

    2015-11-01

    Excitation of surface plasmon waves in extrinsic graphene is studied using a full-wave electromagnetic field solver as analysis engine. Particular emphasis is placed on the role played by spatial dispersion due to the finite size of the two-dimensional material at the micro-scale. A simple instructive set up is considered where the near field of a wire antenna is held at sub-micrometric distance from a disk-shaped graphene patch. The key-input of the simulation is the graphene conductivity tensor at terahertz frequencies, being modeled by the Boltzmann transport equation for the valence and conduction electrons at the Dirac points (where a linear wave-vector dependence of the band energies is assumed). The conductivity equation is worked out in different levels of approximations, based on the relaxation time ansatz with an additional constraint for particle number conservation. Both drift and diffusion currents are shown to significantly contribute to the spatially dispersive anisotropic features of micro-scale graphene. More generally, spatial dispersion effects are predicted to influence not only plasmon propagation free of external sources, but also typical scanning probe microscopy configurations. The paper sets the focus on plasmon excitation phenomena induced by near field probes, being a central issue for the design of optical devices and photonic circuits.

  19. Dynamic Localization of Electronic Excitation in Photosynthetic Complexes Revealed with Chiral Two-Dimensional Spectroscopy

    PubMed Central

    Fidler, Andrew F.; Singh, Ved P.; Long, Phillip D.; Dahlberg, Peter D.; Engel, Gregory S.

    2014-01-01

    Time-resolved ultrafast optical probes of chiral dynamics provide a new window allowing us to explore how interactions with such structured environments drive electronic dynamics. Incorporating optical activity into time-resolved spectroscopies has proven challenging due to the small signal and large achiral background. Here, we demonstrate that two-dimensional electronic spectroscopy can be adapted to detect chiral signals and that these signals reveal how excitations delocalize and contract following excitation. We dynamically probe the evolution of chiral electronic structure in the light harvesting complex 2 of purple bacteria following photoexcitation by creating a chiral two-dimensional mapping. The dynamics of the chiral two-dimensional signal directly reports on changes in the degree of delocalization of the excitonic state following photoexcitation. The mechanism of energy transfer in this system may enhance transfer probability due to the coherent coupling among chromophores while suppressing fluorescence that arises from populating delocalized states. This generally applicable spectroscopy will provide an incisive tool to probe ultrafast transient molecular fluctuations that are obscured in non-chiral experiments. PMID:24504144

  20. Publications for Bart Anderson Anderson, B. (2015). Bart Anderson. Current Biology, 25(15),

    E-print Network

    Müller, Dietmar

    2015-01-01

    ] Ratnasingam, S., Anderson, B. (2015). The role of chromatic variance in modulating color appearance. Journal, B. (2014). The perceptual organzation of depth, lightness, color, and opacity. In John S Werner, Leo surface completion in stereoscopic transparency. Frontiers in Psychology, 3(SEP 2012), 1-11.

  1. Quantum criticality at the Anderson transition: A typical medium theory perspective

    NASA Astrophysics Data System (ADS)

    Mahmoudian, Samiyeh; Tang, Shao; Dobrosavljevi?, Vladimir

    2015-10-01

    We present a complete analytical and numerical solution of the typical medium theory (TMT) for the Anderson metal-insulator transition. This approach self-consistently calculates the typical amplitude of the electronic wave functions, thus representing the conceptually simplest order-parameter theory for the Anderson transition. We identify all possible universality classes for the critical behavior, which can be found within such a mean-field approach. This provides insights into how interaction-induced renormalizations of the disorder potential may produce qualitative modifications of the critical behavior. We also formulate a simplified description of the leading critical behavior, thus obtaining an effective Landau theory for Anderson localization.

  2. Localization in active incommensurate arrays

    E-print Network

    T. V. Laptyeva; S. V. Denisov; G. V. Osipov; M. V. Ivanchenko

    2014-12-01

    In a dissipationless linear lattice, spatial disorder or incommensurate modulation induce localization of the lattice eigenstates and block spreading of wave packets. Additionally, incommensurate arrays allow for the metal-insulator transition at a finite modulation amplitude already in one dimension. The addition of nonlinearity to the lattice Hamiltonian causes interaction between the eigenstates, which results in a slow packet spreading. We go beyond the dissipationless limit and consider nonlinear quasi-periodic arrays that are subjected to the dissipative losses and energy pumping. We find that there is a finite excitation of oscillations threshold in both metallic and insulating regimes. Moreover, excitation in the metallic and weakly insulating regime displays features of the second order phase transition to global oscillations, in contrast to disordered arrays. The Anderson attractor regime is recovered only in the limit of strong localization. The identified transition, and the further onset of chaos and synchronization can be potentially realized with polariton condensates lattices and cavity-QED arrays.

  3. Characterization of Two-photon Excitation Fluorescence Lifetime Imaging Microscopy for Protein Localization

    E-print Network

    Localization YE CHEN1 AND AMMASI PERIASAMY1,2 * 1 W.M. Keck Center for Cellular Imaging, University of Virginia-Rad Radiance2100 confocal/mul- tiphoton microscopy system. Microsc. Res. Tech. 63:72­80, 2004. © 2003 Wiley in probe fluorescence lifetime provides an enormous ad- vantage for imaging dynamic cellular events (Herman

  4. Direct picosecond time resolution of unimolecular reactions initiated by local mode excitation

    NASA Technical Reports Server (NTRS)

    Scherer, N. F.; Doany, F. E.; Zewail, A. H.; Perry, J. W.

    1986-01-01

    Attention is given to the first results of direct, picosec measurements of the Delta-nu(OH) 5 local mode transition of H2O2. These time-resolved studies yield a direct measure of the unimolecular dissociation rate, and furnish a lower limit for the rate of energy redistribution from the OH stretch to the O-O reaction coordinate. The data thus determined may be used to ascertain the domain of validity for statistical unimolecular reaction rate theories.

  5. Spectroscopic manifestations of local crystal distortions in excited 4f states in crystals of huntite structure

    SciTech Connect

    Malakhovskii, A. V.; Gnatchenko, S. L.; Kachur, I. S.; Piryatinskaya, V. G.; Sukhachev, A. L.; Sokolov, A. E.; Strokova, A. Ya.; Kartashev, A. V.; Temerov, V. L.

    2013-01-15

    Optical absorption spectra of YbAl{sub 3}(BO{sub 3}){sub 4}, TmAl{sub 3}(BO{sub 3}){sub 4} and TbFe{sub 3}(BO{sub 3}){sub 4} trigonal crystals have been studied in temperature range 2-300 K. Temperature behavior of absorption lines parameters has shown, that during some f-f transitions the local environment of rare earth ions undergo distortions, which are absent in the ground state.

  6. Conservation laws, radiative decay rates, and excited state localization in organometallic complexes with strong spin-orbit coupling.

    PubMed

    Powell, B J

    2015-01-01

    There is longstanding fundamental interest in 6-fold coordinated d(6) (t(2g)(6)) transition metal complexes such as [Ru(bpy)3](2+) and Ir(ppy)3, particularly their phosphorescence. This interest has increased with the growing realisation that many of these complexes have potential uses in applications including photovoltaics, imaging, sensing, and light-emitting diodes. In order to design new complexes with properties tailored for specific applications a detailed understanding of the low-energy excited states, particularly the lowest energy triplet state, T1, is required. Here we describe a model of pseudo-octahedral complexes based on a pseudo-angular momentum representation and show that the predictions of this model are in excellent agreement with experiment - even when the deviations from octahedral symmetry are large. This model gives a natural explanation of zero-field splitting of T1 and of the relative radiative rates of the three sublevels in terms of the conservation of time-reversal parity and total angular momentum modulo two. We show that the broad parameter regime consistent with the experimental data implies significant localization of the excited state. PMID:26123864

  7. Conservation laws, radiative decay rates, and excited state localization in organometallic complexes with strong spin-orbit coupling

    E-print Network

    B. J. Powell

    2015-01-05

    There is longstanding fundamental interest in 6-fold coordinated $d^6$ ($t_{2g}^6$) transition metal complexes such as [Ru(bpy)$_3$]$^{2+}$ and Ir(ppy)$_3$, particularly their phosphorescence. This interest has increased with the growing realisation that many of these complexes have potential uses in applications including photovoltaics, imaging, sensing, and light-emitting diodes. In order to design new complexes with properties tailored for specific applications a detailed understanding of the low-energy excited states, particularly the lowest energy triplet state, $T_1$, is required. Here we describe a model of pseudo-octahedral complexes based on a pseudo-angular momentum representation and show that the predictions of this model are in excellent agreement with experiment - even when the deviations from octahedral symmetry are large. This model gives a natural explanation of zero-field splitting of $T_1$ and of the relative radiative rates of the three sublevels in terms of the conservation of time-reversal parity and total angular momentum modulo two. We show that the broad parameter regime consistent with the experimental data implies significant localization of the excited state.

  8. Conservation laws, radiative decay rates, and excited state localization in organometallic complexes with strong spin-orbit coupling

    PubMed Central

    Powell, B. J.

    2015-01-01

    There is longstanding fundamental interest in 6-fold coordinated d6 () transition metal complexes such as [Ru(bpy)3]2+ and Ir(ppy)3, particularly their phosphorescence. This interest has increased with the growing realisation that many of these complexes have potential uses in applications including photovoltaics, imaging, sensing, and light-emitting diodes. In order to design new complexes with properties tailored for specific applications a detailed understanding of the low-energy excited states, particularly the lowest energy triplet state, T1, is required. Here we describe a model of pseudo-octahedral complexes based on a pseudo-angular momentum representation and show that the predictions of this model are in excellent agreement with experiment - even when the deviations from octahedral symmetry are large. This model gives a natural explanation of zero-field splitting of T1 and of the relative radiative rates of the three sublevels in terms of the conservation of time-reversal parity and total angular momentum modulo two. We show that the broad parameter regime consistent with the experimental data implies significant localization of the excited state. PMID:26123864

  9. Local response to light excitation in the charge-ordered phase of (EDO-TTF ) 2Sb F6

    NASA Astrophysics Data System (ADS)

    Servol, Marina; Moisan, Nicolas; Collet, Eric; Cailleau, Hervé; Kaszub, Wawrzyniec; Toupet, Loïc; Boschetto, Davide; Ishikawa, Tadahiko; Moréac, Alain; Koshihara, Shinya; Maesato, Mitsuhiko; Uruichi, Mikio; Shao, Xiangfeng; Nakano, Yoshiaki; Yamochi, Hideki; Saito, Gunzi; Lorenc, Maciej

    2015-07-01

    The family of materials (EDO-TTF ) 2X F6 represents quasi-one-dimensional quarter filled systems exhibiting insulator-to-metal (I-M) phase transition at thermal equilibrium. (EDO-TTF ) 2P F6 is known to undergo a photoinduced I-M conversion with cooperative response to light excitation. Here we use femtosecond pump-probe experiments to study the photoresponse of (EDO-TTF ) 2Sb F6 made of a larger counteranion Sb F6 compared to the well studied (EDO-TTF ) 2P F6 . In the early stage of the photoinduced process, we reveal a multicomponent coherent oscillating feature. The evolution of this feature with excitation density and temperature points to the local nature of the photoswitching in (EDO-TTF ) 2Sb F6 . At longer time scale, we did not detect the features associated with the transformation to the M phase, albeit observed in the P F6 derivative. We propose a scenario whereby the bigger size of the counteranion in (EDO-TTF ) 2Sb F6 hinders the establishment of this transformation at macroscopic scale.

  10. Anderson testifies on Planet Earth

    NASA Astrophysics Data System (ADS)

    Wainger, Lisa A.

    AGU president Don Anderson joined former astronaut Sally Ride and National Aeronautics and Space Administration official Lennard Fisk March 8 in testifying before the Senate committee on Commerce, Science, and Transportation. The three had been asked to speak on the future of the Mission to Planet Earth, proposed both in a National Academy of Sciences report and a NASA study.Anderson was chairman of the National Academy of Science's Task Group on Earth Sciences, which prepared the report Mission to Planet Earth as part of the series Space Science in the Twenty-First Century. In his testimony, Anderson highlighted parts of the report and quoted the frontispiece “We now have the technology and the incentive to move boldly forward on a Mission to Planet Earth. We call on the nation to implement an integrated global program using both spaceborne and earth-based instrumentation for fundamental research on the origin, evolution and nature of our planet, its place in our solar system, and its interaction with living things, including mankind.”

  11. Unified parameter for localization in isotope-selective rotational excitation of diatomic molecules using a train of optical pulses

    NASA Astrophysics Data System (ADS)

    Matsuoka, Leo

    2015-04-01

    We obtained a simple theoretical unified parameter for the characterization of rotational population propagation of diatomic molecules in a periodic train of terahertz optical pulses around the condition of so-called quantum resonance. The parameter comprises the peak intensity and interval between the pulses, and the level energies of the initial and final rotational states of the molecule. Using the unified parameter, we can predict the upper and lower boundaries of probability localization on the rotational level network, including the effect of centrifugal distortion. The unified parameter was tentatively derived from an analytical expression obtained by performing rotating-wave approximation and spectral decomposition of the time-dependent Schrödinger equation under an assumption of time-order invariance. The validity of the parameter was confirmed by comparison with numerical simulations for isotope-selective rotational excitation of KCl molecules.

  12. Unified parameter for localization in isotope-selective rotational excitation of diatomic molecules using a train of optical pulses

    E-print Network

    Leo Matsuoka

    2015-01-27

    We obtained a simple theoretical unified parameter for the characterization of rotational population propagation of diatomic molecules in a periodic train of resonant optical pulses. The parameter comprises the peak intensity and interval between the pulses, and the level energies of the initial and final rotational states of the molecule. Using the unified parameter, we can predict the upper and lower boundaries of probability localization on the rotational level network, including the effect of centrifugal distortion. The unified parameter was tentatively derived from an analytical expression obtained by performing rotating-wave approximation and spectral decomposition of the time-dependent Schr\\"{o}dinger equation under an assumption of time-order invariance. The validity of the parameter was confirmed by comparison with numerical simulations for isotope-selective rotational excitation of KCl molecules.

  13. Kubo-Anderson Mixing in the Turbulent Boundary Layer

    NASA Astrophysics Data System (ADS)

    Dekker, H.; de Leeuw, G.; Brink, A. Maassen Van Den

    A novel ab initio analysis of the Reynolds stress is presented in order to model non-local turbulence transport. The theory involves a sample path space and a stochastic hypothesis. A scaling relation maps the path space onto the boundary layer. Analytical sampling rates are shown to model mixing by exchange. Nonlocal mixing involves a scaling exponent ??0.58 (??? in the diffusion limit). The resulting transport equation represents a nondiffusive (Kubo-Anderson or kangaroo) type stochastic process.

  14. A rational reduction of CI expansions: combining localized molecular orbitals and selected charge excitations.

    PubMed

    Krah, Tim; Ben Amor, Nadia; Maynau, Daniel; Berger, J A; Robert, Vincent

    2014-07-01

    Based on localized molecular orbitals, the proposed method reduces large configuration interaction (CI) spaces while maintaining agreement with reference values. Our strategy concentrates the numerical effort on physically pertinent CI-contributions and is to be considered as a tool to tackle large systems including numerous open-shells. To show the efficiency of our method we consider two 4-electron parent systems. First, we illustrate our approach by describing the van der Waals interactions in the (H2)2 system. By systematically including local correlation, dispersion and charge transfer mechanisms, we show that 90% of the reference full CI dissociation energy of the H2 dimer is reproduced using only 3% of the full CI space. Second, the conformational cis/trans rotation barrier of the butadiene molecule is remarkably reproduced (97% of the reference value) with less than 1% of the reference space. This work paves the way to numerical strategies which afford the electronic structure determination of large open-shell systems avoiding the exponential limitation. At the same time, a physical analysis of the contents of the wave function is offered. PMID:24935105

  15. Local chemical reaction of benzene on Cu(110) via STM-induced excitation

    NASA Astrophysics Data System (ADS)

    Komeda, T.; Kim, Y.; Fujita, Y.; Sainoo, Y.; Kawai, Maki

    2004-03-01

    We have investigated the mechanism of the chemical reaction of the benzene molecule adsorbed on Cu(110) surface induced by the injection of tunneling electrons using scanning tunneling microscopy (STM). With the dosing of tunneling electrons of the energy 2-5 eV from the STM tip to the molecule, we have detected the increase of the height of the benzene molecule by 40% in the STM image and the appearance of the vibration feature of the ?(C-H) mode in the inelastic tunneling spectroscopy (IETS) spectrum. It can be understood with a model in which the dissociation of C-H bonds occurs in a benzene molecule that induces a bonding geometry change from flat-lying to up-right configuration, which follows the story of the report of Lauhon and Ho on the STM-induced change of benzene on the Cu(100) surface. [L. J. Lauhon and W. Ho, J. Phys. Chem. A 104, 2463 (2000)]. The reaction probability shows a sharp rise at the sample bias voltage at 2.4 V, which saturates at 3.0 V, which is followed by another sharp rise at the voltage of 4.3 V. No increase of the reaction yield is observed for the negative sample voltage up to 5 eV. In the case of a fully deuterated benzene molecule, it shows the onset at the same energy of 2.4 eV, but the reaction probability is 103 smaller than the case of the normal benzene molecule. We propose a model in which the dehydrogenation of the benzene molecule is induced by the formation of the temporal negative ion due to the trapping of the electrons at the unoccupied resonant states formed by the ? orbitals. The existence of the resonant level close to the Fermi level (˜2.4 eV) and multiple levels in less than ˜5 eV from the Fermi level, indicates a fairly strong interaction of the Cu-?* state of the benzene molecule. We estimated that the large isotope effect of ˜103 can be accounted for with the Menzel-Gomer-Redhead (MGR) model with an assumption of a shallow potential curve for the excited state.

  16. Statistics of excitations in the electron glass model

    NASA Astrophysics Data System (ADS)

    Palassini, Matteo

    2011-03-01

    We study the statistics of elementary excitations in the classical electron glass model of localized electrons interacting via the unscreened Coulomb interaction in the presence of disorder. We reconsider the long-standing puzzle of the exponential suppression of the single-particle density of states near the Fermi level, by measuring accurately the density of states of charged and electron-hole pair excitations via finite temperature Monte Carlo simulation and zero-temperature relaxation. We also investigate the statistics of large charge rearrangements after a perturbation of the system, which may shed some light on the slow relaxation and glassy phenomena recently observed in a variety of Anderson insulators. In collaboration with Martin Goethe.

  17. Circularly polarized luminescence spectroscopy reveals low-energy excited states and dynamic localization of vibronic transitions in CP43.

    PubMed

    Hall, Jeremy; Renger, Thomas; Picorel, Rafael; Krausz, Elmars

    2016-01-01

    Circularly polarized luminescence (CPL) spectroscopy is an established but relatively little-used technique that monitors the chirality of an emission. When applied to photosynthetic pigment assemblies, we find that CPL provides sensitive and detailed information on low-energy exciton states, reflecting the interactions, site energies and geometries of interacting pigments. CPL is the emission analog of circular dichroism (CD) and thus spectra explore the optical activity only of fluorescent states of the pigment-protein complex and consequently the nature of the lowest-energy excited states (trap states), whose study is a critical area of photosynthesis research. In this work, we develop the new approach of temperature-dependent CPL spectroscopy, over the 2-120K temperature range, and apply it to the CP43 proximal antenna protein of photosystem II. Our results confirm strong excitonic interactions for at least one of the two well-established emitting states of CP43 named "A" and "B". Previous structure-based models of CP43 spectra are evaluated in the light of the new CPL data. Our analysis supports the assignments of Shibata et al. [Shibata et al. J. Am. Chem. Soc. 135 (2013) 6903-6914], particularly for the highly-delocalized B-state. This state dominates CPL spectra and is attributed predominantly to chlorophyll a's labeled Chl 634 and Chl 636 (alternatively labeled Chl 43 and 45 by Shibata et al.). The absence of any CPL intensity in intramolecular vibrational sidebands associated with the delocalized "B" excited state is attributed to the dynamic localization of intramolecular vibronic transitions. PMID:26449206

  18. Local Control Model of Excitation–Contraction Coupling in Skeletal Muscle

    PubMed Central

    Stern, Michael D.; Pizarro, Gonzalo; Ríos, Eduardo

    1997-01-01

    This is a quantitative model of control of Ca2+ release from the sarcoplasmic reticulum in skeletal muscle, based on dual control of release channels (ryanodine receptors), primarily by voltage, secondarily by Ca2+ (Ríos, E., and G. Pizarro. 1988. NIPS. 3:223–227). Channels are positioned in a double row array of between 10 and 60 channels, where exactly half face voltage sensors (dihydropyridine receptors) in the transverse (t) tubule membrane (Block, B.A., T. Imagawa, K.P. Campbell, and C. Franzini-Armstrong. 1988. J. Cell Biol. 107:2587–2600). We calculate the flux of Ca2+ release upon different patterns of pulsed t-tubule depolarization by explicit stochastic simulation of the states of all channels in the array. Channels are initially opened by voltage sensors, according to an allosteric prescription (Ríos, E., M. Karhanek, J. Ma, A. González. 1993. J. Gen. Physiol. 102:449–482). Ca2+ permeating the open channels, diffusing in the junctional gap space, and interacting with fixed and mobile buffers produces defined and changing distributions of Ca2+ concentration. These concentrations interact with activating and inactivating channel sites to determine the propagation of activation and inactivation within the array. The model satisfactorily simulates several whole-cell observations, including kinetics and voltage dependence of release flux, the “paradox of control,” whereby Ca2+-activated release remains under voltage control, and, most surprisingly, the “quantal” aspects of activation and inactivation (Pizarro, G., N. Shirokova, A. Tsugorka, and E. Ríos. 1997. J. Physiol. 501:289–303). Additionally, the model produces discrete events of activation that resemble Ca2+ sparks (Cheng, H., M.B. Cannell, and W.J. Lederer. 1993. Science (Wash. DC). 262:740–744). All these properties result from the intersection of stochastic channel properties, control by local Ca2+, and, most importantly, the one dimensional geometry of the array and its mesoscopic scale. Our calculations support the concept that the release channels associated with one face of one junctional t-tubule segment, with its voltage sensor, constitute a functional unit, termed the “couplon.” This unit is fundamental: the whole cell behavior can be synthesized as that of a set of couplons, rather than a set of independent channels. PMID:9379173

  19. Anderson transition and multifractals in the spectrum of the Dirac operator of quantum chromodynamics at high temperature

    NASA Astrophysics Data System (ADS)

    Ujfalusi, László; Giordano, Matteo; Pittler, Ferenc; Kovács, Tamás G.; Varga, Imre

    2015-11-01

    We investigate the Anderson transition found in the spectrum of the Dirac operator of quantum chromodynamics at high temperature, studying the properties of the critical quark eigenfunctions. Applying multifractal finite-size scaling we determine the critical point and the critical exponent of the transition, finding agreement with previous results, and with available results for the unitary Anderson model. We estimate several multifractal exponents, finding also in this case agreement with a recent determination for the unitary Anderson model. Our results confirm the presence of a true Anderson localization-delocalization transition in the spectrum of the quark Dirac operator at high temperature, and further support that it belongs to the 3D unitary Anderson model class.

  20. Spin-dependent localized Hartree-Fock density-functional calculation of singly, doubly, and triply excited and Rydberg states of He- and Li-like ions

    E-print Network

    Chu, Shih-I; Zhou, Zhongyuan

    2005-02-28

    A spin-dependent density-functional approach for the calculation of highly and multiply excited state of atomic system is proposed based on the localized Hartree-Fock density-functional method and Slater’s diagonal sum rule. In this approach...

  1. Damage detection of metro tunnel structure through transmissibility function and cross correlation analysis using local excitation and measurement

    NASA Astrophysics Data System (ADS)

    Feng, Lei; Yi, Xiaohua; Zhu, Dapeng; Xie, Xiongyao; Wang, Yang

    2015-08-01

    In a modern metropolis, metro rail systems have become a dominant mode for mass transportation. The structural health of a metro tunnel is closely related to public safety. Many vibration-based techniques for detecting and locating structural damage have been developed in the past several decades. However, most damage detection techniques and validation tests are focused on bridge and building structures; very few studies have been reported on tunnel structures. Among these techniques, transmissibility function and cross correlation analysis are two well-known diagnostic approaches. The former operates in frequency domain and the latter in time domain. Both approaches can be applied to detect and locate damage through acceleration data obtained from sensor arrays. Furthermore, the two approaches can directly utilize structural response data without requiring excitation measurement, which offers advantages in field testing on a large structure. In this research, a numerical finite element model of a metro tunnel is built and different types of structural defects are introduced at multiple locations of the tunnel. Transmissibility function and cross correlation analysis are applied to perform structural damage detection and localization, based on simulated structural vibration data. Numerical results demonstrate that the introduced defects can be successfully identified and located. The sensitivity and feasibility of the two approaches have been verified when sufficient distribution of measurement locations is available. Damage detection results of the two different approaches are compared and discussed.

  2. Localized excitation of magnetostatic surface spin waves in yttrium iron garnet by shorted coaxial probe detected via spin pumping and rectification effect

    SciTech Connect

    Soh, Wee Tee Ong, C. K.; Peng, Bin

    2015-04-21

    We demonstrate the localized excitation and dc electrical detection of magnetostatic surface spin waves (MSSWs) in yttrium iron garnet (YIG) by a shorted coaxial probe. Thin films of NiFe and Pt are patterned at different regions onto a common bulk YIG substrate. A shorted coaxial probe is used to excite spin precession locally near various patterned regions. The dc voltages across the corresponding regions are recorded. For excitation of the Pt regions, the dc voltage spectra are dominated by the spin pumping of MSSWs from YIG, where various modes can be clearly distinguished. For the NiFe region, it is also found that spin pumping from MSSWs generated in YIG dominated the spectra, indicating that the spin pumped currents are dissipated into charge currents via the inverse Spin Hall effect (ISHE) in NiFe. For all regions, dc signals from YIG MSSWs are observed to be much stronger than the ferromagnetic resonance (FMR) uniform mode, likely due to the nature of the microwave excitation. The results indicate the potential of this probe for microwave imaging via dc detection of spin dynamics in continuous and patterned films.

  3. Coherent Backscattering Reveals the Anderson Transition

    NASA Astrophysics Data System (ADS)

    Ghosh, S.; Delande, D.; Miniatura, C.; Cherroret, N.

    2015-11-01

    We develop an accurate finite-time scaling analysis of the angular width of the coherent backscattering (CBS) peak for waves propagating in 3D random media. Applying this method to ultracold atoms in optical speckle potentials, we show how to determine both the mobility edge and the critical exponent of the Anderson transition from the temporal behavior of the CBS width. Our method could be used in experiments to fully characterize the 3D Anderson transition.

  4. Quantum phase transitions in a pseudogap Anderson-Holstein model

    NASA Astrophysics Data System (ADS)

    Cheng, Mengxing; Ingersent, Kevin

    2013-02-01

    We study a pseudogap Anderson-Holstein model of a magnetic impurity level that hybridizes with a conduction band whose density of states vanishes in power-law fashion at the Fermi energy, and couples, via its charge, to a nondispersive bosonic mode (e.g., an optical phonon). The model, which we treat using poor-man's scaling and the numerical renormalization group, exhibits quantum phase transitions of different types depending on the strength of the impurity-boson coupling. For weak impurity-boson coupling, the suppression of the density of states near the Fermi energy leads to quantum phase transitions between strong-coupling (Kondo) and local-moment phases. For sufficiently strong impurity-boson coupling, however, the bare repulsion between a pair of electrons in the impurity level becomes an effective attraction, leading to quantum phase transitions between strong-coupling (charge Kondo) and local-charge phases. Even though the Hamiltonian exhibits different symmetries in the spin and charge sectors, the thermodynamic properties near the two types of quantum phase transition are closely related under spin-charge interchange. Moreover, the critical responses to a local magnetic field (for small impurity-boson coupling) and to an electric potential (for large impurity-boson coupling) are characterized by the same exponents, whose values place these quantum-critical points in the universality class of the pseudogap Anderson model. One specific case of the pseudogap Anderson-Holstein model may be realized in a double-quantum-dot device, where the quantum phase transitions manifest themselves in the finite-temperature linear electrical conductance.

  5. Quantum localization without disorder in interacting Bose-Einstein condensates

    E-print Network

    Franzosi, Roberto; Illuminati, Fabrizio

    2010-01-01

    We discuss the possibility of exponential quantum localization in systems of ultracold bosonic atoms with repulsive interactions in open optical lattices without disorder. We show that exponential localization occur in the maximally excited state of the lowest energy band. We establish the conditions under which the presence of the upper energy bands can be neglected, determine the successive stages and the quantum phase boundaries at which localization occurs, and discuss how to detect it experimentally by visibility measurements. The discussed mechanism is a bona fide type of quantum localization, solely due to the interplay between nonlinearity and a bounded energy spectrum. In particular, it does not require the presence of random disorder or other local sources of noise, in striking contrast with Anderson localization.

  6. Lifshitz tails in the 3D Anderson model

    E-print Network

    Alexander Elgart

    2008-04-21

    Consider the 3D Anderson model with a zero mean and bounded i.i.d. random potential. Let $\\lambda$ be the coupling constant measuring the strength of the disorder, and $\\sigma(E)$ the self energy of the model at energy $E$. For any $\\epsilon>0$ and sufficiently small $\\lambda$, we derive almost sure localization in the band $E \\le -\\sigma(0)-\\lambda^{4-\\epsilon}$. In this energy region, we show that the typical correlation length $\\xi_E$ behaves roughly as $O((|E|-\\sigma(E))^{-1/2})$, completing the argument outlined in the unpublished work of T. Spencer.

  7. The Use of Digital Ink in Lecture Presentation Richard Anderson, Ruth Anderson!!!!, Crystal Hoyer,

    E-print Network

    Anderson, Richard

    The Use of Digital Ink in Lecture Presentation Richard Anderson, Ruth Anderson!!!!, Crystal Hoyer 600 800 1000 1200 1 2 3 4 5 6 7 8 Professor B Segmentation of ink strokes for two lectures Professional Masters' Program class Webviewer for lecture replay Instructor view of Classroom Presenter Ink

  8. H{sub 2} EXCITATION STRUCTURE ON THE SIGHTLINES TO {delta} SCORPII AND {zeta} OPHIUCI: FIRST RESULTS FROM THE SUB-ORBITAL LOCAL INTERSTELLAR CLOUD EXPERIMENT

    SciTech Connect

    France, Kevin; Nell, Nicholas; Kane, Robert; Green, James C.; Burgh, Eric B.

    2013-07-20

    We present the first science results from the Sub-orbital Local Interstellar Cloud Experiment (SLICE): moderate resolution 1020-1070 A spectroscopy of four sightlines through the local interstellar medium. High signal-to-noise (S/N) spectra of {eta} Uma, {alpha} Vir, {delta} Sco, and {zeta} Oph were obtained during a 2013 April 21 rocket flight. The SLICE observations constrain the density, molecular photoexcitation rates, and physical conditions present in the interstellar material toward {delta} Sco and {zeta} Oph. Our spectra indicate a factor of two lower total N(H{sub 2}) than previously reported for {delta} Sco, which we attribute to higher S/N and better scattered light control in the new SLICE observations. We find N(H{sub 2}) = 1.5 Multiplication-Sign 10{sup 19} cm{sup -2} on the {delta} Sco sightline, with kinetic and excitation temperatures of 67 and 529 K, respectively, and a cloud density of n{sub H} = 56 cm{sup -3}. Our observations of the bulk of the molecular sightline toward {zeta} Oph are consistent with previous measurements (N(H{sub 2}) Almost-Equal-To 3 Multiplication-Sign 10{sup 20} cm{sup -2} at T{sub 01}(H{sub 2}) = 66 K and T{sub exc} = 350 K). However, we detect significantly more rotationally excited H{sub 2} toward {zeta} Oph than previously observed. We infer a cloud density in the rotationally excited component of n{sub H} Almost-Equal-To 7600 cm{sup -3} and suggest that the increased column densities of excited H{sub 2} are a result of the ongoing interaction between {zeta} Oph and its environment; also manifest as the prominent mid-IR bowshock observed by WISE and the presence of vibrationally excited H{sub 2} molecules observed by the Hubble Space Telescope.

  9. Describing excited state relaxation and localization in TiO2 nanoparticles using TD-DFT

    SciTech Connect

    Berardo, Enrico; Hu, Han -Shi; van Dam, Hubertus J. J.; Shevlin, Stephen A.; Woodley, Scott M.; Kowalski, Karol; Zwijnenburg, Martijn A.

    2014-02-26

    We have investigated the description of excited state relaxation in naked and hydrated TiO2 nanoparticles using Time-Dependent Density Functional Theory (TD-DFT) with three common hybrid exchange-correlation (XC) potentials; B3LYP, CAM-B3LYP and BHLYP. Use of TD-CAM-B3LYP and TD-BHLYP yields qualitatively similar results for all structures, which are also consistent with predictions of coupled cluster theory for small particles. TD-B3LYP, in contrast, is found to make rather different predictions; including apparent conical intersections for certain particles that are not observed with TD-CAM-B3LYP nor with TD-BHLYP. In line with our previous observations for vertical excitations, the issue with TD-B3LYP appears to be the inherent tendency of TD-B3LYP, and other XC potentials with no or a low percentage of Hartree-Fock Like Exchange, to spuriously stabilize the energy of charge-transfer (CT) states. Even in the case of hydrated particles, for which vertical excitations are generally well described with all XC potentials, the use of TD-B3LYP appears to result in CT-problems for certain particles. We hypothesize that the spurious stabilization of CT-states by TD-B3LYP even may drive the excited state optimizations to different excited state geometries than those obtained using TD-CAM-B3LYP or TD-BHLYP. In conclusion, focusing on the TD-CAM-B3LYP and TD-BHLYP results, excited state relaxation in naked and hydrated TiO2 nanoparticles is predicted to be associated with a large Stokes’ shift.

  10. Evidence of excited state localization and static disorder in LH2 investigated by 2D-polarization single-molecule imaging at room temperature.

    PubMed

    Tubasum, Sumera; Camacho, Rafael; Meyer, Matthias; Yadav, Dheerendra; Cogdell, Richard J; Pullerits, Tõnu; Scheblykin, Ivan G

    2013-12-01

    Two-dimensional polarization fluorescence imaging of single light harvesting complexes 2 (LH2) of Rps. acidophila was carried out to investigate the polarization properties of excitation and fluorescence emission simultaneously, at room temperature. In two separate experiments we excited LH2 with a spectrally narrow laser line matched to the absorption bands of the two chromophore rings, B800 and B850, thereby indirectly and directly triggering fluorescence of the B850 exciton state. A correlation analysis of the polarization modulation depths in excitation and emission for a large number of single complexes was performed. Our results show, in comparison to B800, that the B850 ring is a more isotropic absorber due to the excitonic nature of its excited states. At the same time, we observed a strong tendency for LH2 to emit with dipolar character, from which preferential localization of the emissive exciton, stable for minutes, is inferred. We argue that the observed effects can consistently be explained by static energetic disorder and/or deformation of the complex, with possible involvement of exciton self-trapping. PMID:24145962

  11. Universality and the QCD Anderson transition.

    PubMed

    Giordano, Matteo; Kovács, Tamás G; Pittler, Ferenc

    2014-03-14

    We study the Anderson-type transition previously found in the spectrum of the QCD quark Dirac operator in the high-temperature, quark-gluon plasma phase. Using finite size scaling for the unfolded level spacing distribution, we show that in the thermodynamic limit there is a genuine mobility edge, where the spectral statistics changes from Poisson to Wigner-Dyson statistics in a nonanalytic way. We determine the correlation length critical exponent ? and find that it is compatible with that of the unitary Anderson model. PMID:24679282

  12. New superconducting state of the Anderson-lattice model

    SciTech Connect

    Lee, D.H. ); Zimanyi, G.T. )

    1989-11-01

    We discuss the possible existence of a new superconducting state, the two-component superconducting (TCSC) state, of the Anderson-lattice model, when the antiferromagnetic Heisenberg exchange energy {ital J}{sub {ital H}} generated by the hybridization between the conduction band and localized orbitals exceeds a constant multiple of the Kondo energy {ital k}{sub {ital B}}T{sub K}. In this new state, holes in both the conduction band and localized orbitals exhibit two-particle off-diagonal long-range order, and the condensate wave function is a coherent mixture of both types of singlet pairs. We propose that the TCSC phase is a possible candidate for the superconducting phase in the high-{ital T}{sub {ital c}} copper oxides.

  13. The Lost Career of Paul Y. Anderson.

    ERIC Educational Resources Information Center

    Lambeth, Edmund B.

    1983-01-01

    Examines major episodes in the reporting career of Paul Y. Anderson, Washington, D.C., newspaper correspondent and magazine columnist, to see how he helped maintain the practice and standing of enterprise journalism in the 1920s and 1930s. (FL)

  14. Peter G. Anderson, Computer Science Department

    E-print Network

    Anderson, Peter G.

    of identical clones A Genetic Algorithm must combine · Exploration (e.g., random search) · Exploitation (e#12;GA Issues Peter G. Anderson, Computer Science Department Rochester Institute of Technology & create two children Add the children to the new population pg. 12 #12;Mutation: Preserve Genetic

  15. The conductivity measure for the Anderson model

    E-print Network

    Abel Klein; Peter Müller

    2007-09-21

    We study the ac-conductivity in linear response theory for the Anderson tight-binding model. We define the electrical ac-conductivity and calculate the linear-response current at zero temperature for arbitrary Fermi energy. In particular, the Fermi energy may lie in a spectral region where extended states are believed to exist.

  16. Lifshits tails in the hierarchical Anderson model

    E-print Network

    Simon Kuttruf; Peter Müller

    2011-08-21

    We prove that the homogeneous hierarchical Anderson model exhibits a Lifshits tail at the upper edge of its spectrum. The Lifshits exponent is given in terms of the spectral dimension of the homogeneous hierarchical structure. Our approach is based on Dirichlet-Neumann bracketing for the hierarchical Laplacian and a large-deviation argument.

  17. Forecasting Total Risk Greg Anderson y

    E-print Network

    Forecasting Total Risk #3; Greg Anderson y Barra, Inc. Lisa Goldberg y Barra, Inc. Alec N. Kercheval z Florida State University Guy Miller y Barra, Inc. Kathy Sorge y Barra, Inc. May 1, 2003 x, optimization. y Barra, Inc., 2100 Milvia Street, Berkeley, CA 94704 USA z Department of Mathematics, Florida

  18. The Anderson Quin Cycle. Final report

    SciTech Connect

    Anderson, J.H.; Bilbow, W.M.

    1993-03-18

    The objective of this study was to make a more refined evaluation of the Anderson Quin Cycle based on most recent information on the performance of various elements that will be used in the Anderson Quin Cycle. My original estimate of the work plan for evaluating and optimizing the Anderson Quin Cycle called for 7000 man hours of work. Since this grant was limited to 2150 man hours, we could not expect to achieve all the objectives within the allotted period of work. However, the most relevant program objectives have been completed as reported here. The analysis generally confirms the results originally estimated in my paper on the subject. (Ref. 2) Further optimizations should show even higher efficiencies. The Anderson Quin Cycle (US Patent applied for) basically consists of 5 elements in the power cycle: A refrigeration system to cool and clean the inlet air before it enters the compressor that supplies air for the gas turbine; a gas turbine consisting of a compressor, combustor, and turbine; a steam boiler and steam turbine system using the heat from the exhaust gas out of the gas turbine; a vapor turbine cycle, which utilizes the condensed heat from the exhaust of the steam turbine and the exhaust gas heat leaving the steam boiler to operate a vapor turbine cycle which utilizes another fluid than water, in this case isobutane; and the fifth element consists of a gas cooler and heat pump system, which removes the heat from the exhaust gas to lower its temperature essentially to atmospheric temperature, and at the same time permits treatment of the exhaust gas to remove acid components such as sulfur dioxide and nitrogen oxides. Current industry accepted component characteristics were incorporated in the performance analysis of the overall cycle, ensuring accurate and meaningful operating predictions. The characteristics and performance of each of the elements are described. The thermal efficiency of the optimized calculated Anderson Quin Cycle is 62 percent.

  19. Theoretical Study of One-Electron Oxidized Mn(III)- and Ni(II)-Salen Complexes: Localized vs Delocalized Ground and Excited States in Solution.

    PubMed

    Aono, Shinji; Nakagaki, Masayuki; Kurahashi, Takuya; Fujii, Hiroshi; Sakaki, Shigeyoshi

    2014-03-11

    One-electron oxidized Mn(III)- and Ni(II)-salen complexes exhibit unique mixed-valence electronic structures and charge transfer (CT) absorption spectra. We theoretically investigated them to elucidate the reason why the Mn(III)-salen complex takes a localized electronic structure (class II mixed valence compound by Robin-Day classification) and the Ni(II)-analogue has a delocalized one (class III) in solution, where solvation effect was taken into consideration either by the three-dimensional reference interaction site model self-consistent field (3D-RISM-SCF) method or by the mean-field (MF) QM/MM-MD simulation. The geometries of these complexes were optimized by the 3D-RISM-SCF-U-DFT/M06. The vertical excitation energy and the oscillator strength of the first excited state were evaluated by the general multiconfiguration reference quasi-degenerate perturbation theory (GMC-QDPT), including the solvation effect based on either 3D-RISM-SCF- or MF-QM/MM-MD-optimized solvent distribution. The computational results well agree with the experimentally observed absorption spectra and the experimentally proposed electronic structures. The one-electron oxidized Mn(III)-salen complex with a symmetrical salen ligand belongs to the class II, as experimentally reported, in which the excitation from the phenolate anion to the phenoxyl radical moiety occurs. In contrast, the one-electron oxidized Ni(II)-salen complex belongs to the class III, in which the excitation occurs from the doubly occupied delocalized ?1 orbital of the salen radical to the singly occupied delocalized ?2 orbital; the ?1 is a bonding combination of the HOMOs of two phenolate moieties and the ?2 is an antibonding combination. Solvation effect is indispensable for correctly describing the mixed-valence character, the geometrical distortion, and the intervalence CT absorption spectra of these complexes. The number of d electrons and the d orbital energy level play crucial roles to provide the localization/delocalization character of these complexes. PMID:26580183

  20. Wet Interface of Benzylhexadecyldimethylammonium Chloride Reverse Micelle Revealed by Excited State Proton Transfer of a Localized Probe.

    PubMed

    Phukon, Aparajita; Barman, Nabajeet; Sahu, Kalyanasis

    2015-11-24

    Excited state proton transfer (ESPT) of an anionic photoacid 8-hydroxypyrene-1,3,6-trisulfonic acid (HPTS or pyranine) has been studied inside a cationic reverse micelle (RM), water/benzylhexadecyldimethylammonium chloride (BHDC)/benzene, using steady-state and time-resolved fluorescence spectroscopy. The observed ESPT behavior is found to be remarkably different from the known ESPT trend of HPTS inside anionic AOT and cationic CTAB RMs; the ESPT dynamics approaches that of bulk water at higher w0 (?10) inside AOT RM while no ESPT was observed for CTAB reverse micelle [ Sedgwick J. Am. Chem. Soc. 2012 , 134 , 11904 - 11907 ]. The ESPT dynamics inside BHDC RM is remarkably slower compared to that of water at all w0 (= [water]/[surfactant]) values and relatively much less sensitive to w0 variation compared to AOT RM. 2D NOESY and fluorescence anisotropy measurements reveal that the probe (HPTS) is embedded inside the positive interface of BHDC RM. Despite its trapped location, HPTS is able to undergo ESPT due to significant penetration of water molecules into the interface. Furthermore, facile ESPT at higher w0 is consistent with higher degree of interface hydration as predicted by a recent MD simulation [ Agazzi Langmuir 2014 , 30 , 9643 - 9653 ]. The study shows that ESPT dynamics inside RM varies not only with the interface charge but also on the nature of the headgroup and solvation. PMID:26540303

  1. Nuclear excitation by electron transition rate confidence interval in a Hg201 local thermodynamic equilibrium plasma

    NASA Astrophysics Data System (ADS)

    Comet, M.; Gosselin, G.; Méot, V.; Morel, P.; Pain, J.-C.; Denis-Petit, D.; Gobet, F.; Hannachi, F.; Tarisien, M.; Versteegen, M.

    2015-11-01

    Nuclear excitation by electron transition (NEET) is predicted to be the dominant excitation process of the first Hg201 isomeric state in a laser heated plasma. This process may occur when the energy difference between a nuclear transition and an atomic transition is close to zero, provided the quantum selection rules are fulfilled. At local thermodynamic equilibrium, an average atom model may be used, in a first approach, to evaluate the NEET rate in plasma. The statistical nature of the electronic transition spectrum is then described by the means of a Gaussian distribution around the average atom configuration. However, using a continuous function to describe the electronic spectrum is questionable in the framework of a resonant process, such as NEET. In order to get an idea of when it can be relied upon to predict a NEET rate in plasma, we present in this paper a NEET rate calculation using a model derived from detailed configuration accounting. This calculation allows us to define a confidence interval of the NEET rate around its average atom mean value, which is the first step to design a future experiment.

  2. Surface hopping dynamics using a locally diabatic formalism: Charge transfer in the ethylene dimer cation and excited state dynamics in the 2-pyridone dimer

    NASA Astrophysics Data System (ADS)

    Plasser, Felix; Granucci, Giovanni; Pittner, Jiri; Barbatti, Mario; Persico, Maurizio; Lischka, Hans

    2012-12-01

    In this work, the advantages of a locally diabatic propagation of the electronic wave function in surface hopping dynamics proceeding on adiabatic surfaces are presented providing very stable results even in challenging cases of highly peaked nonadiabatic interactions. The method was applied to the simulation of transport phenomena in the stacked ethylene dimer radical cation and the hydrogen bonded 2-pyridone dimer. Systematic tests showed the reliability of the method, in situations where standard methods relying on an adiabatic propagation of the wave function and explicit calculation of the nonadiabatic coupling terms exhibited significant numerical instabilities. Investigations of the ethylene dimer radical cation with an intermolecular distance of 7.0 Å provided a quantitative description of diabatic charge trapping. For the 2-pyidone dimer, a complex dynamics was obtained: a very fast (<10 fs) initial S2/S1 internal conversion; subsequent excitation energy transfers with a characteristic time of 207 fs; and the occurrence of proton coupled electron transfer (PCET) in 26% of the trajectories. The computed characteristic excitation energy transfer time of 207 fs is in satisfactory agreement with the experimental value of 318 fs derived from the vibronic exciton splittings in a monodeuterated 2-pyridone dimer complex. The importance of nonadiabatic coupling for the PCET related to the electron transfer was demonstrated by the dynamics simulations.

  3. Femtosecond hole-burning spectroscopy of the dye DCM in solution: the transition from the locally excited to a charge-transfer state

    NASA Astrophysics Data System (ADS)

    Kovalenko, S. A.; Ernsting, N. P.; Ruthmann, J.

    1996-08-01

    Transient spectra of the styryl dyM (4-dicyanomethylene-2-methyl-6- p-dimethylaminostyryl-4H-pyran) in methanol were studied by the pump-supercontinuum probe technique with 40 fs time resolution. A theory of measurements with a supercontinuum probe is presented. Gain and absorption spectra were measured from 400 to 800 nm with 1.5 nm resolution. Before 70 fs, prominent spectral structure is observed which is mainly due to resonant Raman processes. At longer times the spectrum undergoes a red shift and change of shape (time constant 140 fs) with a well-defined isosbestic point. After 300 fs solvation becomes apparent. The early transient spectrum is assigned to the locally excited state of DCM.

  4. Detection of Influenza Virus with Specific Subtype by Using Localized Surface Plasmons Excited on a Flat Metal Surface

    NASA Astrophysics Data System (ADS)

    Ning, Jun; Nagata, Kotaro; Ainai, Akira; Hasegawa, Hideki; Kano, Hiroshi

    2013-08-01

    We report on a method to determine subtype of influenza viruses by using surface plasmons localized in microscopic region on a flat metal surface. In this method, refractive index variation arisen from interactions between viruses and their monoclonal antibodies is measured. The developed sensor shows stability of refractive index in the order of 10-4 against sample exchange. In our experiment, A/H1N1 viruses are distinguished from A/H3N2 viruses by using monoclonal antibodies immobilized on the metal surface. Since the measurement probe has the volume of ˜6 al, the method has potential to handle multiple subtypes in the measurement of a sample with ultra small volume.

  5. Nonlinear energy channeling in the two-dimensional, locally resonant, unit-cell model. II. Low energy excitations and unidirectional energy transport

    NASA Astrophysics Data System (ADS)

    Vorotnikov, K.; Starosvetsky, Y.

    2015-07-01

    This paper completes a series of two publications devoted to the analytical investigation of energy channeling phenomena, emerging in a locally resonant unit-cell model. The system under consideration comprises an outer mass with internal rotator and subject to the 2D nonlinear local potential. In the present study, we focus on the analysis of the regimes of two-dimensional, nonlinear energy transport forming in the special asymptotic limit of low energy excitations. Unlike the previously considered case, this limit can also be characterized by the absence of resonant interactions between the internal rotator and the motion of an outer element. In the considered limit, we report the emergence of all new, highly nonlinear, transient regimes of unidirectional energy channeling. This phenomenon is manifested by partial and complete targeted energy flow from axial to lateral vibrations, controlled by an internal device. Here, we also show that regimes corresponding to the bidirectional energy channeling as well as the spontaneous energy locking reported in the first paper of the series—persist in the low energy limit as well. In this study, we use a regular multi-scale asymptotic procedure and completely unveil the intrinsic mechanisms governing bi- and unidirectional energy channeling. Numerical simulations are found to be in a fairly good agreement with the predictions of analytic model.

  6. Comment on 'Mapping of localized spin-wave excitations by near-field Brillouin light scattering' [Appl. Phys. Lett. 97, 152502 (2010)].

    SciTech Connect

    Giovannini, L.; Montoncello, F.; Nizzoli, F.; Vavassori, P.; Grimsditch, M.

    2011-11-04

    The authors reported in their letter some outstanding experimental results of spin excitations in nano-particles investigated by near-field Brillouin scattering. They conclude from their observations that existing theories -- in particular micromagnetic simulations -- do not correctly describe the behavior of the spin modes. Since excellent agreement has been reported between spin-wave mode frequencies obtained from Brillouin scattering experiments and those obtained from micromagnetic-based simulations, it is somewhat surprising that the simulations should fail for the particles investigated in Ref. 1. In the literature, there is also evidence of various kinds and degrees of mode localization when exchange competes with dipolar interactions. When dipolar long-range interactions are taken into account, the eigenmodes can be seen as the superposition of plane waves, leading to different localizations and in particular to the appearence of bulk-dead modes. We have simulated the normal modes of the particles used in Ref. 1, with the dynamical matrix method; the results are shown in Fig. 1 for different values of the applied field. In addition to the lowest frequency non-localized mode (1-BA), several localized modes are present. Large particles exhibit modes with oscillations along the field direction;8 for such modes, we use the label n-BA-loc, with n the number of nodes. While the profile of the pure end-mode, i.e., 0-BA-loc, has its maximum at the edge with the amplitude monotonously decreasing toward the interior of the ellipse, as correctly described by the authors, the localized modes with n > 0, not considered by them, do not have this characteristic: see inset of Fig. 1. Based on Fig. 1, we believe that the assumption that the mode they observe is 'the' localized spin mode is not correct. Instead, we believe that the mode detected in the experiment at H > 700 Oe is a combinations (due to non-linear excitation conditions of the experiment) of several n-BA-loc modes, with n?>?0. In this picture, the sharp peaks of the n-BA-loc modes are smoothed in the experimental measurements, thanks to the superposition of modes with different nodal lines. Finally, at 350 Oe, the measured profile and frequency suggest that the mode seen in the experiment may be well due to the 1-BA mode. The observed change in mode profile at 350 Oe is substantiated by the frequency behavior shown in Fig. 3(b) of Ref. 1, where it can be observed that the frequency of the low-field point does not lie on the same curve as the high-field points. In summary, before concluding that micromagnetic-based simulations of spin wave modes in nano-particles are unreliable, we believe that it is necessary to await either the simulation of large particles using small cell sizes or for more exhaustive experiments reaching lower frequencies on particles of varying size. The comparison of calculations with experiment would greatly benefit if the authors were to provide the field dependence of all the modes detected in their experiment (in order to achieve a proper assignment).

  7. Theory of Anderson pseudospin resonance with Higgs mode in superconductors

    NASA Astrophysics Data System (ADS)

    Tsuji, Naoto; Aoki, Hideo

    2015-08-01

    A superconductor illuminated by an ac electric field with frequency ? is theoretically found to generate a collective precession of Anderson's pseudospins, and hence a coherent amplitude oscillation of the order parameter, with a doubled frequency 2 ? through a nonlinear light-matter coupling. We provide a fundamental theory, based on the mean-field formalism, to show that the induced pseudospin precession resonates with the Higgs amplitude mode of the superconductor at 2 ? =2 ? with 2 ? being the superconducting gap. The resonant precession is accompanied by a divergent enhancement of the third-harmonic generation (THG). By decomposing the THG susceptibility into the bare one and vertex correction, we find that the enhancement of the THG cannot be explained by individual quasiparticle excitations (pair breaking), so that the THG serves as a smoking gun for an identification of the collective Higgs mode. We further explore the effect of electron-electron scattering on the pseudospin resonance by applying the nonequilibrium dynamical mean-field theory to the attractive Hubbard model driven by ac electric fields. The result indicates that the pseudospin resonance is robust against electron correlations, although the resonance width is broadened due to electron scattering, which determines the lifetime of the Higgs mode.

  8. Surface excitations in a Bose-Einstein condensate Collective modes which have no radial nodes and are localized close to the surface of

    E-print Network

    Surface excitations in a Bose-Einstein condensate Collective modes which have no radial nodes these excitations can be considered the mesoscopic counterpart to tidal waves at the macroscopic level. Those excitations are of special interest since they show a crossover between collective and single

  9. A Study of Diagrammatic Ink in Lecture Richard Anderson a

    E-print Network

    Anderson, Richard

    A Study of Diagrammatic Ink in Lecture Richard Anderson a Ruth Anderson b Crystal Hoyer a Craig ink, identifying phases in discussion of a diagram, and constructing the active context in a diagram. The technology to support presentation is rapidly advancing, in particular, there is growing use of digital ink

  10. The University of Texas MD Anderson Cancer Center

    Cancer.gov

    The University of Texas MD Anderson Cancer Center (MD Anderson) was established by the Texas State Legislature in 1941and is a free-standing, degree-granting health institution within The University of Texas System. Mission areas include patient care, research, education, and prevention.

  11. Magnetoresistance of an Anderson Insulator of Bosons Anirban Gangopadhyay,1

    E-print Network

    Müller, Markus

    in speckle potentials (where artificial gauge fields can mimic a magnetic field), as well as in disordered insulators. We describe the change in spatial decay of localized excitations in response to a magnetic field). We explain the observed scaling using a simplified droplet model which incorporates the nontrivial

  12. Cryogenic exciter

    SciTech Connect

    Bray, James William; Garces, Luis Jose

    2012-03-13

    The disclosed technology is a cryogenic static exciter. The cryogenic static exciter is connected to a synchronous electric machine that has a field winding. The synchronous electric machine is cooled via a refrigerator or cryogen like liquid nitrogen. The static exciter is in communication with the field winding and is operating at ambient temperature. The static exciter receives cooling from a refrigerator or cryogen source, which may also service the synchronous machine, to selected areas of the static exciter and the cooling selectively reduces the operating temperature of the selected areas of the static exciter.

  13. Passive control of buckling deformation via Anderson Localization Phenomenon

    NASA Technical Reports Server (NTRS)

    Elishakoff, Isaac; Li, Y. W.; Starnes, J. H., Jr.

    1998-01-01

    Buckling problems of two types of multi-span elastic plates with transverse stiffeners are considered using a method based on the finite difference calculus. The discreteness of the stiffeners is accounted for. It is found that the torsional rigidity of the stiffener plays an important role in the buckling mode pattern. When the torsional rigidity is properly adjusted, the stiffener can act as an isolator of deformation for the structure at buckling so that the deflection is only limited to a small area.

  14. Jack R. Anderson Jack R. Anderson has had an illustrious career as a music educator in Pennsylvania. Inhis 42

    E-print Network

    Sibille, Etienne

    Jack R. Anderson Jack R. Anderson has had an illustrious career as a music educator in Pennsylvania throughout Pennsylvania, Ohio, and West Virginia. Jack was born and raised in Sharon, Pennsylvania the University of Pittsburgh and a Masters of Education in Music from Edinboro University of Pennsylvania. During

  15. The Role of Contrast in the Perception of Achromatic Transparency: Comment on Singh and Anderson (2002) and Anderson (2003)

    ERIC Educational Resources Information Center

    Albert, Marc K.

    2008-01-01

    M. Singh and B. L. Anderson proposed a perceptual theory of achromatic transparency in which the perceived transmittance of a perceived transparent filter is determined by the ratio of the Michelson contrast seen in the region of transparency to that of the background seen directly. Subsequently, B. L. Anderson, M. Singh, and J. Meng proposed that…

  16. Between a metal and an insulator: the critical state of the Anderson transition

    E-print Network

    Gabriel Lemarié; Hans Lignier; Dominique Delande; Pascal Szriftgiser; Jean Claude Garreau

    2010-05-10

    Using a three-frequency one-dimensional kicked rotor experimentally realized with a cold atomic gas, we study the transport properties at the critical point of the metal-insulator Anderson transition. We accurately measure the time-evolution of an initially localized wavepacket and show that it displays at the critical point a scaling invariance characteristic of this second-order phase transition. The shape of the momentum distribution at the critical point is found to be in excellent agreement with the analytical form deduced from self-consistent theory of localization.

  17. The magnetocaloric effect with critical behavior of a periodic Anderson-like organic polymer.

    PubMed

    Ding, L J; Zhong, Y; Fan, S W; Zhu, L Y

    2016-01-01

    We study the magnetocaloric effect and the critical behavior of a periodic Anderson-like organic polymer using Green's function theory, in which the localized f orbitals hybridize with the conduction orbitals at even sites. The field-induced metal-insulator transitions with the magnetic Grüneisen parameter showing |?h|?T(-1) power-law critical behaviour are revealed, which provides a new thermodynamic means for probing quantum phase transitions. It is found that the competition of up-spin and down-spin hole excitations is responsible for the double peak structure of magnetic entropy change (-?S) for the dominant Kondo coupling case, implying a double magnetic cooling process via demagnetization, which follows a power law dependence of the magnetic field h: -?S?h(n). The local exponent n tends to 1 and 2 below and above TC, while has a minimum of 0.648 at TC, which is in accordance with the experimental observation of perovskite manganites Pr0.55Sr0.45MnO3 and Nd0.55Sr0.45MnO3 (J. Y. Fan et al., Appl. Phys. Lett., 2011, 98, 072508; Europhys. Lett., 2015, 112, 17005) corresponding to the conventional ferromagnets within the mean field theory -?S?h(2/3). At TC, the -?S?h curves with a convex curvature superpose each other for small V values, which are separated by the large V case, distinguishing the RKKY interaction and Kondo coupling explicitly. Furthermore, the critical scaling law n(TC) = 1 + (?- 1)/(? + ?) = 1 + 1/?(1 - 1/?) is related to the critical exponents (?, ?, and ?) extracted from the Arrott-Noakes equation of state and the Kouvel-Fisher method, which fulfill the Widom scaling relation ? = 1 + ??(-1), indicating the self-consistency and reliability of the obtained results. In addition, based on the scaling hypothesis through checking the scaling analysis of magnetization, the M-T-h curves collapse into two independent universal branches below and above TC. PMID:26617276

  18. Anderson metal-insulator transitions with classical magnetic impurities

    SciTech Connect

    Jung, Daniel; Kettemann, Stefan

    2014-08-20

    We study the effects of classical magnetic impurities on the Anderson metal-insulator transition (AMIT) numerically. In particular we find that while a finite concentration of Ising impurities lowers the critical value of the site-diagonal disorder amplitude W{sub c}, in the presence of Heisenberg impurities, W{sub c} is first increased with increasing exchange coupling strength J due to time-reversal symmetry breaking. The resulting scaling with J is compared to analytical predictions by Wegner [1]. The results are obtained numerically, based on a finite-size scaling procedure for the typical density of states [2], which is the geometric average of the local density of states. The latter can efficiently be calculated using the kernel polynomial method [3]. Although still suffering from methodical shortcomings, our method proves to deliver results close to established results for the orthogonal symmetry class [4]. We extend previous approaches [5] by combining the KPM with a finite-size scaling analysis. We also discuss the relevance of our findings for systems like phosphor-doped silicon (Si:P), which are known to exhibit a quantum phase transition from metal to insulator driven by the interplay of both interaction and disorder, accompanied by the presence of a finite concentration of magnetic moments [6].

  19. Promise cut short: the career of William Anderson.

    PubMed

    Beasley, A W

    2012-03-01

    This paper traces the career of William Anderson, naval surgeon and naturalist, who served in Cook's ship Resolution on the second and final voyages, and died of tuberculosis high in the Arctic. PMID:22441070

  20. The influence of local heating by nonlinear pulsed laser excitation on the transmission characteristics of a ZnO nanowire waveguide

    NASA Astrophysics Data System (ADS)

    Voss, Tobias; Svacha, Geoffry T.; Mazur, Eric; Müller, Sven; Ronning, Carsten

    2009-03-01

    We perform a transmission experiment on a ZnO nanowire waveguide to study its transmission characteristics under nonlinear femtosecond-pulse excitation. We find that both the second harmonic and the photoluminescence couple into low-order waveguide modes of the nanowires but with distinctly different efficiencies. We measure the transmission spectrum of a single ZnO nanowire waveguide for near-UV light generated by interband recombination processes. The transmission spectrum allows us to determine the absorption edge of the excited nanowire and to study the temperature profile of the nanowire under femtosecond-pulse excitation.

  1. Magnetic Moments of Chromium-Doped Gold Clusters: The Anderson Impurity Model in Finite Systems

    E-print Network

    Hirsch, K; Langenberg, A; Niemeyer, M; Langbehn, B; Möller, T; Terasaki, A; Issendorff, B v; Lau, J T

    2013-01-01

    The magnetic moment of a single impurity atom in a finite free electron gas is studied in a combined x-ray magnetic circular dichroism spectroscopy and density functional theory study of size-selected free chromium-doped gold clusters. The observed size-dependence of the local magnetic moment can essentially be understood in terms of the Anderson impurity model. Electronic shell closure in the host metal minimizes the interaction of localized impurity states with the confined free electron gas and preserves the full magnetic moment of $\\unit[5]{\\mu_B}$ in $\\mathrm{CrAu}_{2}^{+}$ and $\\mathrm{CrAu}_{6}^{+}$ clusters. Even for open-shell species, large local moments are observed that scale with the energy gap of the gold cluster. This indicates that an energy gap in the free electron gas generally stabilizes the local magnetic moment of the impurity.

  2. Characterization of the Localized Excited State of Monosubstituted Ruthenium (ii) Complexes, and Thermodynamic and Structural Investigations on Langmuir Monolayers and Built-Up Multilayers.

    NASA Astrophysics Data System (ADS)

    Samuels, Alan Christopher

    This dissertation consists of two parts. The first part is contained in chapter one, which describes an Electron Spin Resonance (ESR) investigation of the metal -ligand charge transfer (MLCT) excited state of monodiimine complexes of ruthenium (II). Specifically, the electrochemically reduced mono-substituted diimine complexes [ {rm Ru(bpy)(CN)}_4]^ {2-}, [{rm Ru(bpm)(CN)}_4]^{2- }, and [{rm Ru(bpz)(CN) }_4]^{2-}, where bpy = 2,2^'-bipyridine, bpm = 2,2^'-bipyrimidine, and bpz = 2,2^'-bipyrazine, were characterized by ESR spectroscopy. Well-resolved hyperfine structure (hfs) was observed in all three complexes, and coupling constants were calculated from the observed spectra. The hyperfine coupling constants derived from the ESR spectra indicate that the electronic spin density is largely localized within the pi* orbitals of the reduced species. Emission spectra, solvatochromic absorption spectra, and cyclic voltammetry data are also presented and discussed. The second part of this dissertation constitutes the remaining chapters, and details a comprehensive series of investigations on a monolayer fatty acid film system prepared by the classical Langmuir technique. Specifically, monolayer and multilayer films composed of mixtures of behenic acid and platinum bis(2-(2-thienyl)-pyridine were prepared by the Langmuir-Blodgett and Langmuir-Schaefer techniques, and characterized by FTIR transmission and reflectance-absorbance spectroscopy, visible dichroism, emission spectroscopy, transmission electron microscopy and electron diffraction. Langmuir film properties were investigated as a function of subphase temperature to elucidate the phase changes observed in the pressure-area isotherms for these mixtures. Chromatographic analysis of phenacyl derivatives of the fatty acids coupled with luminescence measurements on the platinum complex was performed to elucidate the composition and structure of the multilayer films. The results suggest that the platinum complex assumes a vertical orientation relative to the substrate in the multilayer films, and retains this relative orientation after expulsion from the fatty acid matrix, which occurs at and below 45 mN/m in the film at the air-water interface.

  3. Anderson-Fabry disease in children.

    PubMed

    Sestito, Simona; Ceravolo, Ferdinando; Concolino, Daniela

    2013-01-01

    Although clinical evidence of major organ damage is typical of adulthood, many of the signs and symptoms of Anderson Fabry Disease (AFD) occur frequently in childhood. The clinical phenotype of AFD in pediatric patients has been described in several studies which show a higher incidence and an earlier onset of symptoms in male patients than in females. These include neurological manifestations (acroparaesthesias, chronic neuropathic pain, hypo-anhidrosis, tinnitus, hearing, loss), gastrointestinal (GI) symptoms (abdominal pain and diarrhea), angiokeratomas, ocular abnormalities (cornea verticillata, tortuous retinal vessels and subcapsular cataracts). Such manifestations may impair quality of life and, because of their unspecific nature, rarely lead to an early diagnosis. In addition, signs of major organ damage (microalbuminuria or proteinuria, urinary hyperfiltration, impaired heart rate variability, left ventricular hypertrophy, stroke) are encountered in children with AFD. Clinical trials of enzyme replacement therapy (ERT) with agalsidase alfa and agalsidase beta have been conducted in children, with clinical and pharmacodinamc effects proved by both enzyme formulations, whereas differences in safety profile and administration were found. Although several studies suggest that ERT should be started before irreversible damage in critical organs have occurred, the issue of when to initiate it has not yet been resolved. More controlled trials must be done in order to demonstrate that an early start of ERT could prevent adult complications and to assess the optimal timing of treatment in children with AFD. This review aims to provide an update of the current understanding for a better approach of pediatric AFD. PMID:23448455

  4. An effective medium approach to the asymptotics of the statistical moments of the parabolic Anderson model and Lifshitz tails

    E-print Network

    Bernd Metzger

    2011-06-28

    Originally introduced in solid state physics to model amorphous materials and alloys exhibiting disorder induced metal-insulator transitions, the Anderson model $H_{\\omega}= -\\Delta + V_{\\omega} $ on $l^2(\\bZ^d)$ has become in mathematical physics as well as in probability theory a paradigmatic example for the relevance of disorder effects. Here $\\Delta$ is the discrete Laplacian and $V_{\\omega} = \\{V_{\\omega}(x): x \\in \\bZ^d\\}$ is an i.i.d. random field taking values in $\\bR$. A popular model in probability theory is the parabolic Anderson model (PAM), i.e. the discrete diffusion equation $\\partial_t u(x,t) =-H_{\\omega} u(x,t)$ on $ \\bZ^d \\times \\bR_+$, $u(x,0)=1$, where random sources and sinks are modelled by the Anderson Hamiltonian. A characteristic property of the solutions of (PAM) is the occurrence of intermittency peaks in the large time limit. These intermittency peaks determine the thermodynamic observables extensively studied in the probabilistic literature using path integral methods and the theory of large deviations. The rigorous study of the relation between the probabilistic approach to the parabolic Anderson model and the spectral theory of Anderson localization is at least mathematically less developed. We see our publication as a step in this direction. In particular we will prove an unified approach to the transition of the statistical moments $$ and the integrated density of states from classical to quantum regime using an effective medium approach. As a by-product we will obtain a logarithmic correction in the traditional Lifshitz tail setting when $V_{\\omega}$ satisfies a fat tail condition.

  5. Anderson’s orthogonality catastrophe in one dimension induced by a magnetic field

    NASA Astrophysics Data System (ADS)

    Konrad Knörr, Hans; Otte, Peter; Spitzer, Wolfgang

    2015-08-01

    According to Anderson’s orthogonality catastrophe, the overlap of the N-particle ground states of a free Fermi gas with and without an (electric) potential decays in the thermodynamic limit. For the finite one-dimensional system various boundary conditions are employed. Unlike the usual setup the perturbation is introduced by a magnetic (vector) potential. Although such a magnetic field can be gauged away in one spatial dimension there is a significant and interesting effect on the overlap caused by the phases. We study the leading asymptotics of the overlap of the two ground states and the two-term asymptotics of the difference of the ground-state energies. In the case of periodic boundary conditions our main result on the overlap is based upon a well-known asymptotic expansion by Fisher and Hartwig on Toeplitz determinants with a discontinuous symbol. In the case of Dirichlet boundary conditions no such result is known to us and we only provide an upper bound on the overlap, presumably of the right asymptotic order.

  6. Analytic Flow Equations for the Fermi Liquid Parameters of the Anderson Impurity Model

    NASA Astrophysics Data System (ADS)

    Pandis, Vassilis; Hewson, Alex C.

    2015-08-01

    The low temperature behavior of a Fermi liquid can be described in terms of quasiparticle excitations that are in 1-1 correspondence with those of the noninteracting system. Because of adiabatic continuity, the Landau parameters, which describe the interactions between the quasiparticles, must evolve continuously as the interactions are turned on and be described by a set of flow equations. For strongly correlated electron systems it is not possible to follow this flow in perturbation theory when the interactions become strong. We explore the idea here of overcoming this problem by renormalizing the quasiparticles in this flow using a renormalized perturbation theory. This approach is tested in the case of a single impurity Anderson model. Analytic flow equations are derived which give excellent results for the Landau parameters in the strong correlation regime.

  7. Modified Anderson Model——Dynamics of Brittle Faulting

    NASA Astrophysics Data System (ADS)

    Tong, H.

    2014-12-01

    Anderson's model has been a basic theory of fault mechanical analysis in one century. However, because of the assumptions, there are some major limitations in Anderson model, and it does not account for frequently observed oblique slips, complicated fault cases in nature and the slips occurring on pre-existing planes of weakness. On the basis of Reactivation Tendency Analysis theory proposed by Tong and Yin (2011), we proposed Modified Anderson model and extended Anderson model from 1) homogeneous media to Inhomogeneous media with pre-existing weakness(es); 2) Andersonian stress state to arbitrary stress state; 3) transient activity trend analysis to fault formation and evolution, and verified with sandbox experiments and natural cases. With Modified Anderson model, we can predict 1) the sequence of fault formation; 2) fault orientations and distribution; 3) slip directions (dip slip, oblique-dip slip, oblique slip, oblique strike slip and strike sip) of different fault when the directions of principal stress, orientations and mechanical properties (cohesion and frictional coefficient) of pre-existing weakness(es) are given. The origin of the complicated fault systems in nature can be explained reasonably. There will be a wide applications for oil and gas exploration and development, coal mining, earthquake risk evaluation, etc.

  8. Renal involvement in Anderson-Fabry disease.

    PubMed

    Sessa, Adalberto; Meroni, Mietta; Battini, Graziana; Righetti, Marco; Maglio, Alessia; Tosoni, Antonella; Nebuloni, Manuela; Vago, Gianluca; Giordano, Ferdinando

    2003-01-01

    Anderson-Fabry disease (AFd) is a rare X-linked lisosomal storage disorder of glycosphingolipid (GL) metabolism, caused by a deficiency of the activity of alpha-galactosidase A (alpha-gal A). The progressive accumulation of GL in tissues results in the clinical manifestations of the disease, that are more evident in hemizygous males, and include characteristic skin lesions (angiokeratomas), neurological symptoms (acroparesthesia), ocular features (cornea verticillata), cardiac involvement (left ventricular enlargement, conduction abnormalities), cerebrovascular manifestations (thromboses, hemorrhage, etc.), and kidney involvement with progression to end-stage renal failure (ESRF). ESRF is a common manifestation in hemizygous males (3rd-5th decade) and death occurs around the 5th decade of life because of severe cardiac and/or cerebrovascular complications. Heterozygous females have an attenuated form of this systemic disease. In the kidney, accumulation of GL occurs in the endothelial cells of every vessel, in the epithelial cells of every tubular segment, and in all kinds of glomerular cells. The broad spectrum of renal lesions is a pathophysiological continuum with progressive impairment in the renal function related to continuous intracellular deposition of GL. Electron microscopic study of renal biopsies shows typical osmiophilic inclusion bodies in the cytoplasm of all kind of renal cells, characterized by concentric lamellation of clear and dark layers (35-50 A of periodicity). ESRF is treated by dialysis and kidney transplantation: neither treatment modifies the progression of the cardiovascular and cerebrovascular lesions due to progressive GL deposition. The outcome of kidney transplantation seems to be similar to that found in other non-diabetic patients, but the survival rate on dialysis is lower than in patients with other causes of ESRF. Nowadays, treatment with enzyme replacement infusion with purified alpha-Gal A, produced by a genetically engineered human cell line or Chinese hamster ovocytes, seems to be effective and safe. PMID:12774774

  9. Near-field optical imaging of light localization in GaN nanocolumn system

    NASA Astrophysics Data System (ADS)

    Sakai, Masaru; Inose, Yuta; Ohtsuki, Tomi; Ema, Kazuhiro; Kishino, Katsumi; Saiki, Toshiharu

    2014-03-01

    The first near-field optical imaging of light localization in a GaN nanocolumn system was performed. The sample used was a randomly arranged GaN nanocolumn with high aspect ratio. We attached an InGaN single quantum well at the apex of each GaN nanocolumn as an illuminant antenna and observed luminescence from the illuminant using an aperture-type scanning near-field optical microscope. By this technique, we directly obtained optical images of luminescence and its spatial distribution for the GaN nanocolumn system. These images, along with histogram analysis, excitation wavelength dependence, and numerical calculations, offer evidence of Anderson localization of light.

  10. VOLUME 89, NUMBER 4 P H Y S I C A L R E V I E W L E T T E R S 22 JULY 2002 Coherent X-Ray Raman Spectroscopy: A Nonlinear Local Probe for Electronic Excitations

    E-print Network

    Mukamel, Shaul

    of coherent Raman spectroscopy provide an excellent real-space probe that carries most valuable structural Spectroscopy: A Nonlinear Local Probe for Electronic Excitations Satoshi Tanaka1,3 and Shaul Mukamel1,2 1-ray frequencies across the valence excitations, it is possible to probe the entire manifold of molecular

  11. Lifshitz tails for matrix-valued Anderson models

    E-print Network

    Hakim Boumaza; Hatem Najar

    2013-10-20

    This paper is devoted to the study of Lifshitz tails for a continuous matrix-valued Anderson-type model $H_{\\omega}$ acting on $L^2(\\R^d)\\otimes \\C^{D}$, for arbitrary $d\\geq 1$ and $D\\geq 1$. We prove that the integrated density of states of $H_{\\omega}$ has a Lifshitz behavior at the bottom of the spectrum. We obtain a Lifshitz exponent equal to $-d/2$ and this exponent is independent of $D$. It shows that the behaviour of the integrated density of states at the bottom of the spectrum of a quasi-d-dimensional Anderson model is the same as its behaviour for a d-dimensional Anderson model.

  12. Fractal Superconductivity near Localization Threshold

    E-print Network

    Fominov, Yakov

    Fractal Superconductivity near Localization Threshold Mikhail Feigel'man Landau Institute, Moscow-electron states are extended but fractal and populate small fraction of the whole volume How BCS theory should be modified to account for eigenstates fractality ? #12;Mean-Field Eq. for Tc #12;#12;3D Anderson model: = 0

  13. Multi-Particle Anderson Localisation: Induction on the Number of Particles

    E-print Network

    Victor Chulaevsky; Yuri Suhov

    2008-11-15

    This paper is a follow-up of our recent papers \\cite{CS08} and \\cite{CS09} covering the two-particle Anderson model. Here we establish the phenomenon of Anderson localisation for a quantum $N$-particle system on a lattice $\\Z^d$ with short-range interaction and in presence of an IID external potential with sufficiently regular marginal cumulative distribution function (CDF). Our main method is an adaptation of the multi-scale analysis (MSA; cf. \\cite{FS}, \\cite{FMSS}, \\cite{DK}) to multi-particle systems, in combination with an induction on the number of particles, as was proposed in our earlier manuscript \\cite{CS07}. Similar results have been recently obtained in an independent work by Aizenman and Warzel \\cite{AW08}: they proposed an extension of the Fractional-Moment Method (FMM) developed earlier for single-particle models in \\cite{AM93} and \\cite{ASFH01} (see also references therein) which is also combined with an induction on the number of particles. An important role in our proof is played by a variant of Stollmann's eigenvalue concentration bound (cf. \\cite{St00}). This result, as was proved earlier in \\cite{C08}, admits a straightforward extension covering the case of multi-particle systems with correlated external random potentials: a subject of our future work. We also stress that the scheme of our proof is \\textit{not} specific to lattice systems, since our main method, the MSA, admits a continuous version. A proof of multi-particle Anderson localization in continuous interacting systems with various types of external random potentials will be published in a separate papers.

  14. Anderson Acceleration of the Alternating Projections Method for Computing the Nearest

    E-print Network

    Higham, Nicholas J.

    Anderson Acceleration of the Alternating Projections Method for Computing the Nearest Correlation ISSN 1749-9097 #12;Anderson Acceleration of the Alternating Projections Method for Computing number of iterations to converge to within a given tolerance. We show that Anderson acceleration

  15. Price-Anderson Amendments Act UT-B Contracts Div Page 1 of 1

    E-print Network

    Price-Anderson Amendments Act UT-B Contracts Div Dec 2010 Page 1 of 1 paaa-ext-dec10.docx PRICE-ANDERSON AMENDMENTS ACT (December 2010) (a) This Agreement is subject to the Price-Anderson Amendments Act, Section 234A of the Atomic Energy Act (AEA) of 1954, as amended, and DOE's implementing regulations at 10 C

  16. Valence fluctuations and electric reconstruction in the extended Anderson model on the two-dimensional Penrose lattice

    NASA Astrophysics Data System (ADS)

    Takemura, Shinichi; Takemori, Nayuta; Koga, Akihisa

    2015-04-01

    We study the extended Anderson model on the two-dimensional Penrose lattice, combining the real-space dynamical mean-field theory with the noncrossing approximation. It is found that the Coulomb repulsion between localized and conduction electrons does not induce a valence transition, but the crossover between the Kondo and mixed valence states is in contrast to the conventional periodic system. In the mixed-valence region close to the crossover, nontrivial valence distributions appear, characteristic of the Penrose lattice, demonstrating that the mixed-valence state coexists with local Kondo states in certain sites. The electric reconstruction in the mixed valence region is also addressed.

  17. Excited Insects

    E-print Network

    Hacker, Randi

    2011-04-06

    but not killing them doesn't actually count as true celebration. Now, China. There's a country that knows how to make a bug feel good. Bugs have their very own holiday in the Chinese calendar. It's called the Feast of the Excited Insects and it falls on March 5th...

  18. Localization of polaritons in disordered polar media

    NASA Astrophysics Data System (ADS)

    Satanin, Arkady; Joe, Yong; Kim, Chang Sub; Vasilevskiy, Mikhail

    2004-03-01

    The main goal of this work is developing a simple theory of polariton propagation in disordered polar media. We have applied the generalized Born-Huang theory to find effective equations for polaritons in inhomogeneous media. In our approach we have considered dielectric functions and phonon-photon coupling parameter as local characteristics of media (random functions). It is shown that the problem of polariton localization may be formulated as the Anderson model with non-symmetric matrix, which describes the coupled phonon-photon modes. We have performed the exact diagonalization of the non-symmetric matrix for two-dimensional systems to find eigenfunctions and eigenvalues near the polaritonic gap. The density of states and some characteristics of localization have been calculated. The investigation of the density of states near the polariton "bottleneck" was shown that when the disorder in the medium is increased, the localized modes appear inside of the polaritonic gap, and then these states form tails inside of the gap. With the increasing of the magnitude of disorder the tails in the gap overlap and the collapse of the gap is occurred. As the strength of disorder is increased the localization is observed to be enhanced over broad energy ranges. To test localization we have investigated a generalized participation ratio, bathed on coupled phonon-photon eigenstates. In addition, the nearest-neighbor level statistics have been investigated. We found different behavior for the level statistics of the upper and lower polaritonic excitations: if the level distribution for the upper branch is a typical Wigner function, then the level distribution for the lower branch has a long tail for the large nearest-neighbor energy intervals. We found a link between this behavior and the peck of density states near the edge of the lower polaritonic band. *Supported by the Indiana 21st Century Research and Technology Fund

  19. Localized excitation effects in (E,E)-2,5- bis[2-(4-N,N-dipropylaminophenyl) ethylenyl]-3,6-dimethylpyrazine and generation of its different forms in solution

    NASA Astrophysics Data System (ADS)

    Nemkovich, N. A.; Detert, H.; Sobchuk, A. N.

    2012-01-01

    Dipole moments of (E,E)-2,5- bis[2-(4-N,N-dipropylaminophenyl)ethylenyl]-3,6-dimethylpyrazine (VS365) quadrupolar dye in 1,4-dioxane and cyclohexane in addition to its instantaneous fluorescence spectra and fluorescence lifetimes in dichloromethane (pure and with added trifluoroacetic acid) were measured. Quantumchemical calculations show that the ? - ? conjugated system is localized in the flattest part of the molecule due to disorder in the ground-state geometry of the dye molecule and that this part is the one responsible for light absorption. The effect of localized excitation of the dye causes a considerable change in its dipole moment ?a?. Various fluorescent forms of the dye that feature considerably spaced emission spectra and different fluorescence lifetimes originate by adding trifluoroacetic acid to the solution of oligophenylenevinylene in dichloromethane.

  20. Visiting Committee Meeting Forest Club Room, Anderson Hall

    E-print Network

    Brown, Sally

    Visiting Committee Meeting Forest Club Room, Anderson Hall October 10, 2007 Attendees: Committee milestone with a celebration of the completion of Phase I of the Pacific Connections Garden reported that the UW, City of Seattle, and Arboretum Botanical Garden Committee have taken the lead to make

  1. A Data Programming CS1 Course Ruth E. Anderson,

    E-print Network

    Ernst, Michael

    programming by means of real-world data analysis. We have found that students can be motivated to learn field, and "Big Data" is in the news everywhere [16]. Graduate students find they need to takeA Data Programming CS1 Course Ruth E. Anderson, Michael D. Ernst University of Washington Seattle

  2. Absolutely Continuous Spectrum for the Anderson Model on Trees

    E-print Network

    Fournier, John J.F.

    on the Green Function at an Arbitrary Site . . . . . . . . . 49 3.5 On a recursion relation.2 The nodes in the recurrence relation for the forward Green function. . . . . 32 3.3 Rearrangement of a tree . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 27 3 Absolutely Continuous Spectrum for the Anderson Model on Some Tree-like Graphs

  3. Markovian Anderson Model: Bounds for the Rate of Propagation

    NASA Astrophysics Data System (ADS)

    Tcheremchantsev, Serguei

    We consider the Anderson model in with potentials whose values at any site of the lattice are Markovian independent random functions of time. For solutions to the time-dependent Schrödinger equation we show under some conditions that with probability 1 where for d=1,2 and for .

  4. TESLA: Temporally Enhanced System Logic Assertions Jonathan Anderson

    E-print Network

    Haddadi, Hamed

    TESLA: Temporally Enhanced System Logic Assertions Jonathan Anderson Robert N. M. Watson David and are not easily expressed in assertions. TESLA is a description, analysis, and validation tool that allows systems can span the interfaces between libraries and even lan- guages. TESLA exposes run-time behaviour using

  5. Best Practices for Lecturing with Digital Ink Richard Anderson

    E-print Network

    Anderson, Richard

    Best Practices for Lecturing with Digital Ink Richard Anderson Department of Computer Science@cs.washington.edu ABSTRACT Systems allowing instructors to write on top of electronic slides with digital ink are becoming widely available. The combination of high quality projected images and rich ink offers new levels

  6. Credit: Michael Anderson. NOAA Selects St. Louis River Estuary as

    E-print Network

    Credit: Michael Anderson. NOAA Selects St. Louis River Estuary as Habitat Focus Area The St. Louis scale. A Watershed in Need The St. Louis River runs along the border of Minnesota and Wisconsin will be an important addition to the restoration effort. The objectives we have identified in the St. Louis River

  7. UCLA ANDERSON SCHOOL OF MANAGEMENT FACULTY EXPERTISE GUIDE

    E-print Network

    Alwan, Abeer

    to view various regions and economies, and instills in students the necessary global social, intellectual knowledge into applicable practices within the global economy. www.anderson.ucla.edu/x27544.xml Ivo Welch watched and often-cited economic outlooks for California and the nation and was unique in predicting both

  8. Mary anderson she received a patent for her

    E-print Network

    Firestone, Jeremy

    Mary anderson she received a patent for her "window cleaning device"in 1903.Within about a decade.s. patent. Hers was granted on July 14, 1885. hedy laMarr a Hollywood star, once dubbed"the most beautiful fabrics. Mary dixon kies In 1809, she received the first U.s. patent awarded to a woman

  9. Interpolation Processes in Object Perception: Reply to Anderson (2007)

    ERIC Educational Resources Information Center

    Kellman, Philip J.; Garrigan, Patrick; Shipley, Thomas F.; Keane, Brian P.

    2007-01-01

    P. J. Kellman, P. Garrigan, & T. F. Shipley presented a theory of 3-D interpolation in object perception. Along with results from many researchers, this work supports an emerging picture of how the visual system connects separate visible fragments to form objects. In his commentary, B. L. Anderson challenges parts of that view, especially the idea…

  10. Fuzzy Xor Classes from Quantum Computing Anderson Avila1

    E-print Network

    Kreinovich, Vladik

    Fuzzy Xor Classes from Quantum Computing Anderson ´Avila1 , Murilo Schmalfuss1 , Renata Reiser1 modelling for fuzzy connectives and the corresponding computations of quantum states can be simultaneously and their dual constructions. So, via quantum computing not only the interpretation based on traditional quantum

  11. Neurological complications of Anderson-Fabry disease.

    PubMed

    Tuttolomondo, Antonino; Pecoraro, Rosaria; Simonetta, Irene; Miceli, Salvatore; Arnao, Valentina; Licata, Giuseppe; Pinto, Antonio

    2013-01-01

    Characteristic clinical manifestations of AFD such as acroparesthesias, angiokeratoma, corneal opacity, hypo/ and anhidrosis, gastrointestinal symptoms, renal and cardiac dysfunctions can occur in male and female patients, although heterozygous females with AFD usually seem to be less severely affected. The most prominent CNS manifestations consist of cerebrovascular events such as transient ischaemic attacks (TIAs) and (recurrent) strokes. For the most part, CNS complications in AFD have been attributed to cerebral vasculopathy, including anatomical abnormalities. The natural history of Fabry patients includes transitory cerebral ischaemia and strokes, even in very young persons of both genders. The mechanism is partly due to vascular endothelial accumulation of Gb-3. White matter lesions (WML) on occur MRI. Both males and females can be safely treated with enzyme replacement; and thus screening for Fabry disease of young stroke populations should be considered. There are, however, no hard data of treatment effect on mortality and morbidity. Stroke in Anderson-Fabry disease study of 721 patients with cryptogenic stroke, aged 18-55 years, showed a high prevalence of Fabry disease in this group: 5% (21/432) of men and 3% (7/289) of women. Combining results of both sexes showed that 4% of young patients with stroke of previously unknown cause had Fabry disease, corresponding to about 1-2% of the general population of young stroke patients. Cerebral micro- and macro-vasculopathy have been described in Fabry disease. Neuronal globotriaosylceramide accumulation in selective cortical and brain stem areas including the hippocampus has been reported by autopsy studies in FD, but clinical surrogates as well as the clinical relevance of these findings have not been investigated so far. Another Neurologic hallmark of Fabry disease (FD) includes small fiber neuropathy as well as cerebral micro- and macroangiopathy with premature stroke. Cranial MRI shows progressive white matter lesions (WML) at an early age, increased signal intensity in the pulvinar, and tortuosity and dilatation of the larger vessels. Conventional MRI shows a progressive load of white matter lesions (WMLs) due to cerebral vasculopathy in the course of FD. Another study has been conducted to quantify brain structural changes in clinically affected male and female patients with FD. The peripheral neuropathy in Fabry disease manifests as neuropathic pain, reduced cold and warm sensation and possibly gastrointestinal disturbances. Patients with Fabry disease begin having pain towards the end of the first decade of life or during puberty. Children as young as 6 years of age have complained of pain often associated with febrile illnesses with reduced heat and exercise tolerance. The patients describe the pain as burning that is often associated with deep ache or paresthesiae. Some patients also have joint pain. A high proportion of patients with Fabry disease is at increased risk of developing neuropsychiatric symptoms, such as depression and neuropsychological deficits. Due to both somatic and psychological impairment, health-related quality of life (QoL) is considerably reduced in patients with Fabry disease. Targeted screening for Fabry disease among young individuals with stroke seems to disclose unrecognized cases and may therefore very well be recommended as routine in the future. Furthermore, ischemic stroke is related to inflammation and arterial stiffness and no study had addressed this relationship in patients with AF disease and cerebrovascular disease, so this topic could represent a possible future research line. PMID:23448452

  12. Excited Delirium

    PubMed Central

    Takeuchi, Asia; Ahern, Terence L.; Henderson, Sean O.

    2011-01-01

    Excited (or agitated) delirium is characterized by agitation, aggression, acute distress and sudden death, often in the pre-hospital care setting. It is typically associated with the use of drugs that alter dopamine processing, hyperthermia, and, most notably, sometimes with death of the affected person in the custody of law enforcement. Subjects typically die from cardiopulmonary arrest, although the cause is debated. Unfortunately an adequate treatment plan has yet to be established, in part due to the fact that most patients die before hospital arrival. While there is still much to be discovered about the pathophysiology and treatment, it is hoped that this extensive review will provide both police and medical personnel with the information necessary to recognize and respond appropriately to excited delirium. PMID:21691475

  13. Excited baryons

    SciTech Connect

    Mukhopadhyay, N.C.

    1986-01-01

    The status of the theory of the low-energy approach to hadron structure is reviewed briefly by surveying a few relevant models. A few examples of tests needed to sort out the predictions of different models pertaining to the quark-gluon structure of hadrons are discussed, and given the resulting physics objectives, a few experimental options for excited baryon research at CFBAF are suggested. (LEW)

  14. Particle Beam Excitation Electron Beam Excitation

    E-print Network

    Schroder, Dieter K.

    Particle Beam Excitation Electron Beam Excitation Scanning Electron Microscopy (SEM) Electron Microprobe Microanalysis (EMP) Transmission Electron Microscopy (TEM) Scanning Auger Microscopy (SAM Backscattering Spectrometry (RBS) X-ray Excitation X-ray Fluorescence (XRF) X-ray Photoelectron Spectroscopy (XPS

  15. Paleontological analysis of a lacustrine carbonaceous uranium deposit at the Anderson mine, Date Creek basin, west-central Arizona (U.S.A.)

    USGS Publications Warehouse

    Otton, J.K.; Bradbury, J.P.; Forester, R.M.; Hanley, J.H.

    1990-01-01

    The Tertiary sedimentary sequence of the Date Creek basin area of Arizona is composed principally of intertonguing alluvial-fan and lacustrine deposits. The lacustrine rocks contain large intermediate- to, locally, high-grade uranium deposits that form one of the largest uranium resources in the United States (an estimated 670,000 tons of U3O8 at an average grade of 0.023% is indicated by drilling to date). At the Anderson mine, about 50,000 tons of U3O8 occurs in lacustrine carbonaceous siltstones and mudstones (using a cutoff grade of 0.01%). The Anderson mine constitutes a new class of ore deposit, a lacustrine carbonaceous uranium deposit. Floral and faunal remains at the Anderson mine played a critical role in creating and documenting conditions necessary for uranium mineralization. Organic-rich, uraniferous rocks at the Anderson mine contain plant remains and ostracodes having remarkably detailed preservation of internal features because of infilling by opaline silica. This preservation suggests that the alkaline lake waters in the mine area contained high concentrations of dissolved silica and that silicification occurred rapidly, before compaction or cementation of the enclosing sediment. Uranium coprecipitated with the silica. Thinly laminated, dark-colored, siliceous beds contain centric diatoms preserved with carbonaceous material suggesting that lake waters at the mine were locally deep and anoxic. These alkaline, silica-charged waters and a stagnant, anoxic environment in parts of the lake were necessary conditions for the precipitation of large amounts of uranium in the lake-bottom sediments. Sediments at the Anderson mine contain plant remains and pollen that were derived from diverse vegetative zones suggesting about 1500 m of relief in the area at the time of deposition. The pollen suggests that the valley floor was semiarid and subtropical, whereas nearby mountains supported temperate deciduous forests. ?? 1990.

  16. Correlation Estimates in the Anderson Model

    NASA Astrophysics Data System (ADS)

    Bellissard, Jean V.; Hislop, Peter D.; Stolz, Günter

    2007-11-01

    We give a new proof of correlation estimates for arbitrary moments of the resolvent of random Schrödinger operators on the lattice that generalizes and extends the correlation estimate of Minami for the second moment. We apply this moment bound to obtain a new n-level Wegner-type estimate that measures eigenvalue correlations through an upper bound on the probability that a local Hamiltonian has at least n eigenvalues in a given energy interval. Another consequence of the correlation estimates is that the results on the Poisson statistics of energy level spacing and the simplicity of the eigenvalues in the strong localization regime hold for a wide class of translation-invariant, selfadjoint, lattice operators with decaying off-diagonal terms and random potentials.

  17. Magnetic Moments of Chromium-Doped Gold Clusters: The Anderson Impurity Model in Finite Systems

    NASA Astrophysics Data System (ADS)

    Hirsch, K.; Zamudio-Bayer, V.; Langenberg, A.; Niemeyer, M.; Langbehn, B.; Möller, T.; Terasaki, A.; Issendorff, B. v.; Lau, J. T.

    2015-02-01

    The magnetic moment of a single impurity atom in a finite free electron gas is studied in a combined x-ray magnetic circular dichroism spectroscopy, charge transfer multiplet calculation, and density functional theory study of size-selected free chromium-doped gold clusters. The observed size dependence of the local magnetic moment can be understood as a transition from a local moment to a mixed valence regime. This shows that the Anderson impurity model essentially describes finite systems even though the discrete density of states introduces a significant deviation from a bulk metal, and the free electron gas is only formed by less than 10 electrons. Electronic shell closure in the gold host minimizes the interaction of localized impurity states with the confined free electron gas and preserves the magnetic moment of 5 ?B fully in CrAu2+ and almost fully in CrAu6+. Even for open-shell species, large local moments are observed that scale with the energy gap of the gold cluster. This indicates that an energy gap in the free electron gas stabilizes the local magnetic moment of the impurity atom.

  18. Competition between Hund's coupling and Kondo effect in a one-dimensional extended periodic Anderson model

    NASA Astrophysics Data System (ADS)

    Hagymási, I.; Sólyom, J.; Legeza, Ö.

    2015-07-01

    We study the ground-state properties of an extended periodic Anderson model to understand the role of Hund's coupling between localized and itinerant electrons using the density-matrix renormalization group algorithm. By calculating the von Neumann entropies we show that two phase transitions occur and two new phases appear as the hybridization is increased in the symmetric half-filled case due to the competition between Kondo effect and Hund's coupling. In the intermediate phase, which is bounded by two critical points, we found a dimerized ground state, while in the other spatially homogeneous phases the ground state is Haldane-like and Kondo-singlet-like, respectively. We also determine the entanglement spectrum and the entanglement diagram of the system by calculating the mutual information thereby clarifying the structure of each phase.

  19. Tunable Anderson metal-insulator transition in quantum spin-Hall insulators

    NASA Astrophysics Data System (ADS)

    Chen, Chui-Zhen; Liu, Haiwen; Jiang, Hua; Sun, Qing-feng; Wang, Ziqiang; Xie, X. C.

    2015-06-01

    We numerically study disorder effects in the Bernevig-Hughes-Zhang (BHZ) model, and we find that the Anderson transition of a quantum spin-Hall insulator (QSHI) is determined by model parameters. The BHZ Hamiltonian is equivalent to two decoupled spin blocks that belong to the unitary class. In contrast to the common belief that a two-dimensional unitary system scales to an insulator except at certain critical points, we find, through calculations scaling properties of the localization length, level statistics, and participation ratio, that a possible exotic metallic phase emerges between the QSHI and normal insulator phases in the InAs/GaSb-type BHZ model. On the other hand, direct transition from a QSHI to a normal insulator is found in the HgTe/CdTe-type BHZ model. Furthermore, we show that the metallic phase originates from the Berry phase and can survive both inside and outside the gap.

  20. Topologically invariant tensor renormalization group method for the Edwards-Anderson spin glasses model

    NASA Astrophysics Data System (ADS)

    Wang, Chuang; Qin, Shao-Meng; Zhou, Hai-Jun

    2014-11-01

    Tensor renormalization group (TRG) method is a real space renormalization group approach. It has been successfully applied to both classical and quantum systems. In this paper, we study a disordered and frustrated system, the two-dimensional Edwards-Anderson model, by a new topological invariant TRG scheme. We propose an approach to calculate the local magnetizations and nearest pair correlations simultaneously. The Nishimori multicritical point predicted by the topological invariant TRG agrees well with the recent Monte Carlo results. The TRG schemes outperform the mean-field methods on the calculation of the partition function. We notice that it might obtain a negative partition function at sufficiently low temperatures. However, the negative contribution can be neglected if the system is large enough. This topological invariant TRG can also be used to study three-dimensional spin glass systems.

  1. Three-Dimensional Numerical Simulation on Passively Excited Flows by Distributed Local Hot Sources Settled at the D" Layer Below Hotspots and/or Large-Scale Cool Masses at Subduction Zones Within the Static Layered Mantle

    NASA Astrophysics Data System (ADS)

    Eguchi, T.; Matsubara, K.; Ishida, M.

    2001-12-01

    To unveil dynamic process associated with three-dimensional unsteady mantle convection, we carried out numerical simulation on passively exerted flows by simplified local hot sources just above the CMB and large-scale cool masses beneath smoothed subduction zones. During the study, we used our individual code developed with the finite difference method. The basic three equations are for the continuity, the motion with the Boussinesq (incompressible) approximation, and the (thermal) energy conservation. The viscosity of our model is sensitive to temperature. To get time integration with high precision, we used the Newton method. In detail, the size and thermal energy of the hot or cool sources are not uniform along the latitude, because we could not select uniform local volumes assigned for the sources within the finite difference grids throughout the mantle. Our results, thus, accompany some latitude dependence. First, we treated the case of the hotspots, neglecting the contribution of the subduction zones. The local hot sources below the currently active hotspots were settled as dynamic driving forces included in the initial condition. Before starting the calculation, we assumed that the mantle was statically layered with zero velocity component. The thermal anomalies inserted instantaneously in the initial condition do excite dynamically passive flows. The type of the initial hot sources was not 'plume' but 'thermal.' The simulation results represent that local upwelling flows which were directly excited over the initial heat sources reached the upper mantle by approximately 30 My during the calculation. Each of the direct upwellings above the hotspots has its own dynamic potential to exert concentric down- and up-welling flows, alternately, at large distances. Simultaneously, the direct upwellings interact mutually within the spherical mantle. As an interesting feature, we numerically observed secondary upwellings somewhere in a wide region covering east Eurasia to the Bering Sea where no hot sources were initially input. It seems that the detailed location of the secondary upwellings depends partly on the numerical parameters such as the radial profile of mantle viscosity especially at the D" layer, etc., because the secondary flows are provoked by dynamic interaction among the distributed direct upwellings just above the CMB. Our results suggest that if we assume not only non-zero time delays during the input of the local hot sources but also parameters related with the difference of their historical surface flux rates, the pattern of the passively excited flows will be different from that obtained with the simultaneously settled hot sources stated above. Second, we simultaneously incorporated simplified thermal anomaly models associated with both the distributed local hotspots and the global subduction zones, as dynamic origins in the initial condition for the static layered mantle. In this case, the simulation result represents that the pattern of secondary radial flows, being different from those in the earlier case, is sensitive to the relative strength between the positive dynamic buoyancy integrated over all of the local hot sources below the hotspots and the total negative buoyancy beneath the subduction zones.

  2. Multi-Stepped Optogenetics: A Novel Strategy to Analyze Neural Network Formation and Animal Behaviors by Photo-Regulation of Local Gene Expression, Fluorescent Color and Neural Excitation

    NASA Astrophysics Data System (ADS)

    Hatta, Kohei; Nakajima, Yohei; Isoda, Erika; Itoh, Mariko; Yamamoto, Tamami

    The brain is one of the most complicated structures in nature. Zebrafish is a useful model to study development of vertebrate brain, because it is transparent at early embryonic stage and it develops rapidly outside of the body. We made a series of transgenic zebrafish expressing green-fluorescent protein related molecules, for example, Kaede and KikGR, whose green fluorescence can be irreversibly converted to red upon irradiation with ultra-violet (UV) or violet light, and Dronpa, whose green fluorescence is eliminated with strong blue light but can be reactivated upon irradiation with UV or violet-light. We have recently shown that infrared laser evoked gene operator (IR-LEGO) which causes a focused heat shock could locally induce these fluorescent proteins and the other genes. Neural cell migration and axonal pattern formation in living brain could be visualized by this technique. We also can express channel rhodopsine 2 (ChR2), a photoactivatable cation channel, or Natronomonas pharaonis halorhodopsin (NpHR), a photoactivatable chloride ion pump, locally in the nervous system by IR. Then, behaviors of these animals can be controlled by activating or silencing the local neurons by light. This novel strategy is useful in discovering neurons and circuits responsible for a wide variety of animal behaviors. We proposed to call this method ‘multi-stepped optogenetics’.

  3. STS-107 Crew Interviews: Michael Anderson, Mission Specialist

    NASA Technical Reports Server (NTRS)

    2002-01-01

    STS-107 Mission Specialist 3 and Payload Commander Michael Anderson is seen during this preflight interview, where he gives a quick overview of the mission before answering questions about his inspiration to become an astronaut and his career path. He outlines his role in the mission in general, and specifically in conducting onboard science experiments. He discusses the following instruments and sets of experiments in detail: CM2 (Combustion Module 2), FREESTAR (Fast Reaction Enabling Science Technology and Research, MEIDEX (Mediterranean Israeli Dust Experiment) and MGM (Mechanics of Granular Materials). Anderson also mentions on-board activities and responsibilities during launch and reentry, mission training, and microgravity research. In addition, he touches on the dual work-shift nature of the mission, the use of crew members as research subjects including pre and postflight monitoring activities, the emphasis on crew safety during training and the value of international cooperation.

  4. Rydberg excitation of Bose-Einstein condensates

    E-print Network

    Rolf Heidemann; Ulrich Raitzsch; Vera Bendkowsky; Björn Butscher; Robert Löw; Tilman Pfau

    2007-10-30

    Rydberg atoms provide a wide range of possibilities to tailor interactions in a quantum gas. Here we report on Rydberg excitation of Bose-Einstein condensed 87Rb atoms. The Rydberg fraction was investigated for various excitation times and temperatures above and below the condensation temperature. The excitation is locally blocked by the van der Waals interaction between Rydberg atoms to a density-dependent limit. Therefore the abrupt change of the thermal atomic density distribution to the characteristic bimodal distribution upon condensation could be observed in the Rydberg fraction. The observed features are reproduced by a simulation based on local collective Rydberg excitations.

  5. Solar hot water system installed at Anderson, South Carolina

    NASA Technical Reports Server (NTRS)

    1978-01-01

    A description is given of the solar energy hot water system installed in the Days Inns of America, Inc., at Anderson, South Carolina. The building is a low-rise, two-story 114-room motel. The solar system was designed to provide 40 percent of the total hot water demand. The collector is a flat plate, liquid with an area of 750 square feet. Operation of this system was begun in November 1977, and has performed flawlessly for one year.

  6. Block Lanczos density-matrix renormalization group method for general Anderson impurity models: Application to magnetic impurity problems in graphene

    NASA Astrophysics Data System (ADS)

    Shirakawa, Tomonori; Yunoki, Seiji

    2014-11-01

    We introduce a block Lanczos (BL) recursive technique to construct quasi-one-dimensional models, suitable for density-matrix renormalization group (DMRG) calculations, from single- as well as multiple-impurity Anderson models in any spatial dimensions. This new scheme, named BL-DMRG method, allows us to calculate not only local but also spatially dependent static and dynamical quantities of the ground state for general Anderson impurity models without losing elaborate geometrical information of the lattice. We show that the BL-DMRG method can be easily extended to treat a multiorbital Anderson impurity model where not only inter- and intraorbital Coulomb interactions but also Hund's coupling and pair hopping interactions are included. We also show that the symmetry adapted BL bases can be utilized, when it is appropriate, to reduce the computational cost. As a demonstration, we apply the BL-DMRG method to three different models for graphene with a structural defect and with a single hydrogen or fluorine absorbed, where a single Anderson impurity is coupled to conduction electrons in the honeycomb lattice. These models include (i) a single adatom on the honeycomb lattice, (ii) a substitutional impurity in the honeycomb lattice, and (iii) an effective model for a single carbon vacancy in graphene. Our analysis of the local dynamical magnetic susceptibility and the local density of states at the impurity site reveals that, for the particle-hole symmetric case at half-filling of electron density, the ground state of model (i) behaves as an isolated magnetic impurity with no Kondo screening, while the ground state of the other two models forms a spin-singlet state where the impurity moment is screened by the conduction electrons. We also calculate the real-space dependence of the spin-spin correlation functions between the impurity site and the conduction sites for these three models. Our results clearly show that, reflecting the presence or absence of unscreened magnetic moment at the impurity site, the spin-spin correlation functions decay as ? r-3, differently from the noninteracting limit (? r-2), for model (i) and as ? r-4, exactly the same as the noninteracting limit, for models (ii) and (iii) in the asymptotic r , where r is the distance between the impurity site and the conduction site. Finally, based on our results, we shed light on recent experiments on graphene where the formation of local magnetic moments as well as the Kondo-like behavior have been observed.

  7. Topological Anderson insulator induced by inter-cell hopping disorder

    SciTech Connect

    Lv, Shu-Hui; Song, Juntao Li, Yu-Xian

    2013-11-14

    We have studied in detail the influence of same-orbit and different-orbit hopping disorders in HgTe/CdTe quantum wells. Intriguingly, similar to the behavior of the on-site Anderson disorder, a phase transition from a topologically trivial phase to a topological phase is induced at a proper strength of the same-orbit hopping disorder. For different-orbit hopping disorder, however, the phase transition does not occur. The results have been analytically verified by using effective medium theory. A consistent conclusion can be obtained by comparing phase diagrams, conductance, and conductance fluctuations. In addition, the influence of Rashba spin-orbit interaction (RSOI) on the system has been studied for different types of disorder, and the RSOI shows different influence on topological phase at different disorders. The topological phase induced by same-orbit hopping disorder is more robust against the RSOI than that induced by on-site Anderson disorder. For different-orbit hopping disorder, no matter whether the RSOI is included or not, the phase transition does not occur. The results indicate, whether or not the topological Anderson insulator can be observed depends on a competition between the different types of the disorder as well as the strength of the RSOI in a system.

  8. Variational exact diagonalization method for Anderson impurity models

    NASA Astrophysics Data System (ADS)

    Schüler, M.; Renk, C.; Wehling, T. O.

    2015-06-01

    We describe a variational approach to solving Anderson impurity models by means of exact diagonalization. Optimized parameters of a discretized auxiliary model are obtained on the basis of the Peierls-Feynman-Bogoliubov principle. Thereby, the variational approach resolves ambiguities related to the bath discretization, which is generally necessary to make Anderson impurity models tractable by exact diagonalization. The choice of variational degrees of freedom made here allows systematic improvements of total energies over mean-field decouplings like Hartree-Fock. Furthermore, our approach allows us to embed arbitrary bath discretization schemes in total-energy calculations and to systematically optimize and improve on traditional routes to the discretization problem such as fitting of hybridization functions on Matsubara frequencies. Benchmarks in terms of a single orbital Anderson model demonstrate that the variational exact diagonalization method accurately reproduces free energies as well as several single- and two-particle observables obtained from an exact solution. Finally, we demonstrate the applicability of the variational exact diagonalization approach to realistic five-orbital problems with the example system of Co impurities in bulk Cu and compare it to continuous-time Monte Carlo calculations. The accuracy of established bath discretization schemes is assessed in the framework of the variational approach introduced here.

  9. Effect of wave localization on plasma instabilities. Ph.D. Thesis

    NASA Technical Reports Server (NTRS)

    Levedahl, William Kirk

    1987-01-01

    The Anderson model of wave localization in random media is involved to study the effect of solar wind density turbulence on plasma processes associated with the solar type III radio burst. ISEE-3 satellite data indicate that a possible model for the type III process is the parametric decay of Langmuir waves excited by solar flare electron streams into daughter electromagnetic and ion acoustic waves. The threshold for this instability, however, is much higher than observed Langmuir wave levels because of rapid wave convection of the transverse electromagnetic daughter wave in the case where the solar wind is assumed homogeneous. Langmuir and transverse waves near critical density satisfy the Ioffe-Reigel criteria for wave localization in the solar wind with observed density fluctuations -1 percent. Numerical simulations of wave propagation in random media confirm the localization length predictions of Escande and Souillard for stationary density fluctations. For mobile density fluctuations localized wave packets spread at the propagation velocity of the density fluctuations rather than the group velocity of the waves. Computer simulations using a linearized hybrid code show that an electron beam will excite localized Langmuir waves in a plasma with density turbulence. An action principle approach is used to develop a theory of non-linear wave processes when waves are localized. A theory of resonant particles diffusion by localized waves is developed to explain the saturation of the beam-plasma instability. It is argued that localization of electromagnetic waves will allow the instability threshold to be exceeded for the parametric decay discussed above.

  10. Astronaut Clay Anderson Speaks With S.C. Students - Duration: 25 minutes.

    NASA Video Gallery

    From NASA's International Space Station Mission Control Center, NASA astronaut Clay Anderson participates in a Digital Learning Network (DLN) event with students at Crayton Middle School, Columbia,...

  11. Systematics and the origin of species from the viewpoint of a botanist: edgar anderson prepares the 1941 jesup lectures with ernst mayr.

    PubMed

    Kleinman, Kim

    2013-01-01

    The correspondence between Edgar Anderson and Ernst Mayr leading into their 1941 Jesup Lectures on "Systematics and the Origin of Species" addressed population thinking, the nature of species, the relationship of microevolution to macroevolution, and the evolutionary dynamics of plants and animals, all central issues in what came to be known as the Evolutionary Synthesis. On some points, they found ready agreement; for others they forged only a short term consensus. They brought two different working styles to this project reflecting their different appreciations of what was possible at this point in evolutionary studies. For Mayr, it was a focused project with definitive short term conclusions imminent while Anderson viewed it as an episode in an ongoing historical process that, while exciting and suggestive, remained openended. Thus, Mayr and Anderson represent two distinct perspectives on the Evolutionary Synthesis in formation; by understanding both of their points of view, we can grasp more fully the state of evolutionary theory at this key moment. PMID:22684268

  12. Band excitation Kelvin probe force microscopy utilizing photothermal excitation

    SciTech Connect

    Collins, Liam E-mail: liq1@ORNL.gov; Rodriguez, Brian J.; Jesse, Stephen; Balke, Nina; Kalinin, Sergei; Li, Qian E-mail: liq1@ORNL.gov

    2015-03-09

    A multifrequency open loop Kelvin probe force microscopy (KPFM) approach utilizing photothermal as opposed to electrical excitation is developed. Photothermal band excitation (PthBE)-KPFM is implemented here in a grid mode on a model test sample comprising a metal-insulator junction with local charge-patterned regions. Unlike the previously described open loop BE-KPFM, which relies on capacitive actuation of the cantilever, photothermal actuation is shown to be highly sensitive to the electrostatic force gradient even at biases close to the contact potential difference (CPD). PthBE-KPFM is further shown to provide a more localized measurement of true CPD in comparison to the gold standard ambient KPFM approach, amplitude modulated KPFM. Finally, PthBE-KPFM data contain information relating to local dielectric properties and electronic dissipation between tip and sample unattainable using conventional single frequency KPFM approaches.

  13. Confinement effect on Anderson-Higgs modes in superfluid 3He-B

    NASA Astrophysics Data System (ADS)

    Mizushima, T.; Sauls, J. A.

    2015-03-01

    Superfluid 3He is a prototype to observe the spectrum of Anderson-Higgs (AH) modes associated with spontaneous symmetry breaking. In bulk superfluid 3He, AH modes have been observed experimentally through attenuation of zero sound, propagation of transverse sound and its acoustic Faraday rotation. Starting from a Lagrangian formulation, we examine the AH modes of 3He-B confined in a restricted geometry. For bulk 3He-B this formalism leads to the well known spectrum of bosonic collectives modes of the bulk B-phase labelled by the quantum numbers for total angular momentum, J = 0 , 1 , 2 , ... , the projection along an axis, Jz = - J , ... , + J , and the parity under particle-hole conversion, K = +/- 1 . For the equilibrium phases of 3He confinement induces pair breaking and leads to symmetry breaking, giving rise to a rich topological phase diagram. In terms of the bosonic excitations, we find that confinement induces symmetry breaking and leads to mixing of modes with different J, as well as to level splittings of the AH modes that are otherwise degenerate in bulk 3He-B. We find a new spectrum of Bosonic modes is generated that are bound to the surface of superfluid 3He in a restricted geometry. We also report on the coupling of the AH modes to ultra-sound.

  14. STS-118 Astronauts Rick Mastracchio and Clay Anderson Perform EVA

    NASA Technical Reports Server (NTRS)

    2007-01-01

    As the construction continued on the International Space Station (ISS), STS-118 astronaut and mission specialist Rick Mastracchio was anchored on the foot restraint of the Canadarm2 as he participated in the third session of Extra Vehicular Activity (EVA) for the mission. Assisting Mastracchio was Expedition 15 flight engineer Clay Anderson (out of frame). During the 5 hour, 28 minute space walk, the two relocated the S-band Antenna Sub-Assembly from the Port 6 (P6) truss to the Port 1 (P1) truss, installed a new transponder on P1 and retrieved the P6 transponder.

  15. STS-107 Payload Commander Michael Anderson checks equipment at SPACEHAB

    NASA Technical Reports Server (NTRS)

    2002-01-01

    KENNEDY SPACE CENTER, FLA. -- STS-107 Payload Commander Michael Anderson checks equipment during training at SPACEHAB. STS-107 is a research mission. The primary payload is the first flight of the SHI Research Double Module (SHI/RDM). The experiments range from material sciences to life sciences (many rats). Also part of the payload is the Fast Reaction Experiments Enabling Science, Technology, Applications and Research (FREESTAR) that incorporates eight high priority secondary attached shuttle experiments. STS-107 is scheduled to launch July 11, 2002

  16. Note: Work function change measurement via improved Anderson method

    SciTech Connect

    Sabik, A. Go?ek, F.; Antczak, G.

    2015-05-15

    We propose the modification to the Anderson method of work function change (??) measurements. In this technique, the kinetic energy of the probing electrons is already low enough for non-destructive investigation of delicate molecular systems. However, in our implementation, all electrodes including filament of the electron gun are polarized positively. As a consequence, electron bombardment of any elements of experimental system is eliminated. Our modification improves cleanliness of the ultra-high vacuum system. As an illustration of the solution capabilities, we present ?? of the Ag(100) surface induced by cobalt phthalocyanine layers.

  17. Event-based Document Sensing for Insider Threats Kenneth Anderson, Antonio Carzaniga, Dennis Heimbigner, Alexander Wolf

    E-print Network

    Wolf, Alexander L.

    Event-based Document Sensing for Insider Threats Kenneth Anderson, Antonio Carzaniga, Dennis University of Colorado Boulder, Colorado 80309-0430 #12;#12;1 Event-based Document Sensing for Insider Threats Kenneth Anderson, Antonio Carzaniga, Dennis Heimbigner, Alexander Wolf 6 February 2004 Abstract

  18. 75 FR 34170 - Plastic Omnium Automotive Exteriors, LLC, Anderson, SC; Plastic Omnium Automotive Exteriors, LLC...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2010-06-16

    ... Assistance on March 18, 2010, applicable to workers of Plastic Omnium Automotive Exteriors, LLC, Anderson, South Carolina. The notice was published in the Federal Register April 23, 2010 (75 FR 21356). The... and Training Administration Plastic Omnium Automotive Exteriors, LLC, Anderson, SC; Plastic...

  19. Benjamin Olney Anderson, MD, FACS Chair and Director, The Breast Health Global Initiative, Fred Hutch

    E-print Network

    Brent, Roger

    Health, University of Washington Director Breast Health Clinic, Seattle Cancer Care Alliance Dr. Anderson practice is devoted to caring for patients with breast health issues and cancer. Dr. Anderson's clinical contributed to the 2005 World Health Organization (WHO) Cancer Prevention and Control Resolution. The American

  20. 78 FR 41835 - Inflation Adjustments to the Price-Anderson Act Financial Protection Regulations

    Federal Register 2010, 2011, 2012, 2013, 2014

    2013-07-12

    ...NRC-2013-0072] RIN 3150-AJ25 Inflation Adjustments to the Price-Anderson Act...specified in the Price-Anderson Act for inflation at least once during each 5-year period...70 FR 61885), and the first periodic inflation adjustments on September 29,...

  1. Phase Boundaries of the Pseudogap Anderson Impurity Model

    NASA Astrophysics Data System (ADS)

    Mohammed, Aaron; Chowdhury, Tathagata; Ingersent, Kevin

    2015-03-01

    As the temperature of metals containing dilute concentrations of magnetic impurities reach very low temperatures, a phenomenon known as the Kondo effect takes place in which the resistance increases. This is due to the domination of spin-exchange processes that occur between the electrons of the metal and the electrons of the magnetic impurity near absolute zero. The Anderson model is a quantum impurity model that was developed in the 1960s to explain this phenomenon. It involves a single magnetic impurity tunnel-coupled to the conduction band of a metal. If the conduction band of this system contains a pseudogap, or a power-law decrease in the density of states around the Fermi energy, then quantum phase transitions will occur. The phase boundaries of the pseudogap Anderson impurity model have been previously approximated using poor man's scaling analysis. Here, we focus on using the more accurate numerical renormalization group method to calculate the location of these boundaries. We then compare these numerical results with the predictions derived from the scaling approximations. The development of nanotechnology like quantum dots and STM have rekindled interest in the Kondo effect since it can now be studied within controlled settings. Supported by the NSF REU Grant DMR-1156737: REU Site in Materials Physics at the University of Florida.

  2. Fluctuations of the Local Density of States Probe Localized Surface Plasmons on Disordered Metal Films

    E-print Network

    Paris 7 - Denis Diderot, Université

    media is stimulated by fundamental issues in mesoscopic physics [1,2], including Anderson localization are a particularly striking example, since they exhibit optical properties that strongly differ from those of bulk states (LDOS) on disordered fractal metallic films. The LDOS is a fundamental quantity

  3. Quench dynamics of Anderson impurity model using configuration interaction method

    NASA Astrophysics Data System (ADS)

    Lin, Chungwei; Demkov, Alexander A.

    2015-10-01

    We study the quench dynamics of an Anderson impurity model using the configuration interaction (CI) method. In particular, we focus on the relaxation behavior of the impurity occupation. The system is found to behave very differently in the weak-coupling and strong-coupling regimes. In the weak-coupling regime, the impurity occupation relaxes to a time-independent constant quickly after only a few oscillations. In the strong-coupling regime, the impurity occupation develops a fast oscillation, with a much slower relaxation. We show that it is the multipeak structure in the many-body energy spectrum that separates these two regimes. The characteristic behavior, including the power-law decay and the period of oscillation, can also be related to certain features in the many-body energy spectrum. The respective advantages of several impurity solvers are discussed, and the convergence of different CI truncation schemes is provided.

  4. Anderson and Stoner Published White Dwarf Mass Limits Before Chandrasekhar

    E-print Network

    Blackman, Eric G

    2011-01-01

    In their engaging recountals of Chandrasekhar's extraordinary career (Physics Today, vol 63, Issue 12, Dec 2010), neither Dyson nor Wali mention that Chandrasekhar was the third person not the first, to publish a white dwarf mass limit incorporating a relativistic treatment of degenerate electrons. As it has become a common misconception that Chandrasekhar was the first, a clarifying reminder on this historical point is warranted. In short, the white dwarf mass limit widely attributed to Chandrasekhar (1931) should be the specific white dwarf mass limit calculated for a polytrope. The insight that a relativistic treatment of degeneracy leads to the existence of a white dwarf mass limit first appeared in papers of W. Anderson (1929) and E.C. Stoner (1930) for a uniform density star. Accordingly, Chandrasekhar (1931) cites Stoner (1930) and points out that the polytrope white dwarf mass limit is less than Stoner's uniform density white dwarf mass limit by about 20%.

  5. Strong feedbacks between hydrology and sliding of a small alpine Robert S. Anderson,1,2

    E-print Network

    Loso, Michael G.

    , Alaska, glacier dynamics, glacial sliding, glacial hydrology, GPS Citation: Anderson, R. S., S. P.1029/2004JF000120. 1. Introduction [2] The rate of subglacier erosion, both by abrasion and by quarrying

  6. Taking on Titan: Meet Carrie Anderson - Duration: 2 minutes, 45 seconds.

    NASA Video Gallery

    When she was a little girl, Carrie Anderson dreamed of becoming an astronomer. Now, as a space scientist at NASA Goddard Space Flight Center, Carrie studies the atmosphere on Titan: one of Saturn's...

  7. An Archaeological Survey of a Proposed Borrow Pit in Anderson County, Texas 

    E-print Network

    Moore, William

    2015-07-10

    An archaeological survey of a 15 acre borrow pit in a floodplain setting adjacent to the Trinity River in northern Anderson County was conducted by Brazos Valley Research Associates in September 2003. Six trackhoe trenches were dug through clay...

  8. A guide to source materials of the life and work of Lawrence B. Anderson '30

    E-print Network

    Laguette, Victoria.

    1998-01-01

    From 1933 to 1976, Professor Lawrence B. Anderson taught in the MIT Department of Architecture, and from 1947 to 1971, he served as its chairman and dean. Concurrently, from 1937 to 1972 , he was principal partner in the ...

  9. Supporting Nested Locking in Multiprocessor Real-Time Systems Bryan C. Ward and James H. Anderson

    E-print Network

    Anderson, James

    Supporting Nested Locking in Multiprocessor Real-Time Systems Bryan C. Ward and James H. Anderson Department of Computer Science, University of North Carolina at Chapel Hill Abstract This paper presents

  10. CONFORMAL IMMERSIONS OF PRESCRIBED MEAN CURVATURE IN R3 MICHAEL T. ANDERSON

    E-print Network

    Anderson, Michael

    CONFORMAL IMMERSIONS OF PRESCRIBED MEAN CURVATURE IN R3 MICHAEL T. ANDERSON Abstract.We prove the existence of (branched) conformal immersions F : S2* *igher genus. 1.Introduction Consider an immersed closed surface

  11. Composite pairing in a mixed-valent two-channel Anderson model

    E-print Network

    Nevidomskyy, Andriy H.

    Using a two-channel Anderson model, we develop a theory of composite pairing in the 115 family of heavy fermion superconductors that incorporates the effects of f-electron valence fluctuations. Our calculations introduce ...

  12. 75 FR 34170 - Plastic Omnium Automotive Exteriors, LLC, Anderson, SC; Plastic Omnium Automotive Exteriors, LLC...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2010-06-16

    ...TA-W-73,230; TA-W-73,230A] Plastic Omnium Automotive Exteriors, LLC, Anderson, SC; Plastic Omnium Automotive Exteriors, LLC, Troy...March 18, 2010, applicable to workers of Plastic Omnium Automotive Exteriors, LLC,...

  13. A review of "Queen Anne: Patroness of Arts" by James Anderson Winn 

    E-print Network

    McClain, Molly

    2015-01-01

    seventeenth-century news James Anderson Winn. Queen Anne: Patroness of Arts. New York: Oxford University Press, 2014. xxi + 792 pp. + 35 illus. + 18 col. pl. + 28 mus. ex. $39.95. Review by Molly McClain, University of San Diego. Known for gambling heavily..., and visual artists. James Anderson Winn reveals the extensive menu of literary, theatrical, and musical entertainments enjoyed by English elites. Unfortunately, he burdens that information with a political narrative and a biography (of sorts) that takes...

  14. Non-Fermi Liquid and Fermi Liquid in Two-Channel Anderson Lattice Model: Theory for PrA2Al20 (A = V, Ti) and PrIr2Zn20

    NASA Astrophysics Data System (ADS)

    Tsuruta, Atsushi; Miyake, Kazumasa

    2015-11-01

    We theoretically investigate electronic states and physical properties in a two-channel Anderson lattice model to understand the non-Fermi liquid behaviors observed in PrV2Al20 and PrIr2Zn20, whose ground state of the crystalline electric field for a local f-electron is the ?3 non-Kramers doublet of f2-configuration and whose excited state is the ?7 Kramers doublet of f1-configuration. We use the expansion from the limit of the large degeneracy N of the ground state (1/N-expansion), with N being the spin–orbital degeneracy. The inclusion of the self-energy of conduction electrons up to the order of O(1/N) leads to heavy electrons with channel and spin–orbit degeneracies. We find that the electrical resistivity is proportional to the temperature T in the limit T ? 0 and follows the sqrt{T} -law in a wide temperature region, i.e., Tx < T < T0, where the typical values of Tx and T0 are Tx ˜ 10?3TK and T0 ˜ 10?2TK, respectively, TK being the Kondo temperature of the model. We also find non-Fermi liquid behaviors at T ? TK in a series of physical quantities; chemical potential, specific heat, and magnetic susceptibility, which explain the non-Fermi liquid behaviors observed in PrV2Al20 and PrIr2Zn20. At the same time, we find that the Fermi liquid behavior becomes prominent for the system with a small hybridization between f- and conduction electrons, explaining the Fermi liquid behaviors observed in PrTi2Al20.

  15. Dynamical localization in molecular alignment of kicked quantum rotors

    NASA Astrophysics Data System (ADS)

    Kamalov, A.; Broege, D. W.; Bucksbaum, P. H.

    2015-07-01

    The periodically ? -kicked quantum linear rotor is known to experience nonclassical bounded energy growth due to quantum dynamical localization in angular momentum space. We study the effect of random deviations of the kick period in simulations and experiments. This breaks the energy and angular momentum localization and increases the rotational alignment, which is the analog of the onset of Anderson localization in one-dimensional chains.

  16. Acoustically excited heated jets. 1: Internal excitation

    NASA Technical Reports Server (NTRS)

    Lepicovsky, J.; Ahuja, K. K.; Brown, W. H.; Salikuddin, M.; Morris, P. J.

    1988-01-01

    The effects of relatively strong upstream acoustic excitation on the mixing of heated jets with the surrounding air are investigated. To determine the extent of the available information on experiments and theories dealing with acoustically excited heated jets, an extensive literature survey was carried out. The experimental program consisted of flow visualization and flowfield velocity and temperature measurements for a broad range of jet operating and flow excitation conditions. A 50.8-mm-diam nozzle was used for this purpose. Parallel to the experimental study, an existing theoretical model of excited jets was refined to include the region downstream of the jet potential core. Excellent agreement was found between theory and experiment in moderately heated jets. However, the theory has not yet been confirmed for highly heated jets. It was found that the sensitivity of heated jets to upstream acoustic excitation varies strongly with the jet operating conditions and that the threshold excitation level increases with increasing jet temperature. Furthermore, the preferential Strouhal number is found not to change significantly with a change of the jet operating conditions. Finally, the effects of the nozzle exit boundary layer thickness appear to be similar for both heated and unheated jets at low Mach numbers.

  17. Trapping and steering on lattice strings: Virtual slow waves and directional and nonpropagating excitations.

    PubMed

    Essl, Georg

    2004-06-01

    Using a lattice string model, a number of peculiar excitation situations related to nonpropagating excitations and nonradiating sources are demonstrated. External fields can be used to trap excitations locally but also lead to the ability to steer such excitations dynamically as long as the steering is slower than the field's wave propagation. I present explicit constructions of a number of examples, including temporally limited nonpropagating excitations, directional excitation and virtually slowed propagation. Using these dynamical lattice constructions I demonstrate that neither persistent temporal oscillation nor static localization are necessary for nonpropagating excitations to occur. PMID:15244758

  18. Exponential Gain in Quantum Computing of Quantum Chaos and Localization

    E-print Network

    B. Georgeot; D. L. Shepelyansky

    2001-03-26

    We present a quantum algorithm which simulates the quantum kicked rotator model exponentially faster than classical algorithms. This shows that important physical problems of quantum chaos, localization and Anderson transition can be modelled efficiently on a quantum computer. We also show that a similar algorithm simulates efficiently classical chaos in certain area-preserving maps.

  19. Spatiotemporal control of nanooptical excitations

    PubMed Central

    Aeschlimann, Martin; Bauer, Michael; Bayer, Daniela; Brixner, Tobias; Cunovic, Stefan; Dimler, Frank; Fischer, Alexander; Pfeiffer, Walter; Rohmer, Martin; Schneider, Christian; Steeb, Felix; Strüber, Christian; Voronine, Dmitri V.

    2010-01-01

    The most general investigation and exploitation of light-induced processes require simultaneous control over spatial and temporal properties of the electromagnetic field on a femtosecond time and nanometer length scale. Based on the combination of polarization pulse shaping and time-resolved two-photon photoemission electron microscopy, we demonstrate such control over nanoscale spatial and ultrafast temporal degrees of freedom of an electromagnetic excitation in the vicinity of a nanostructure. The time-resolved cross-correlation measurement of the local photoemission yield reveals the switching of the nanolocalized optical near-field distribution with a lateral resolution well below the diffraction limit and a temporal resolution on the femtosecond time scale. In addition, successful adaptive spatiotemporal control demonstrates the flexibility of the method. This flexible simultaneous control of temporal and spatial properties of nanophotonic excitations opens new possibilities to tailor and optimize the light–matter interaction in spectroscopic methods as well as in nanophotonic applications. PMID:20212153

  20. Renal ultrastructural findings in Anderson-Fabry disease.

    PubMed

    Sessa, Adalberto; Toson, Antonella; Nebuloni, Manuela; Pallotti, Francesco; Giordano, Ferdinando; Battini, Graziana; Maglio, Alessia; Meroni, Mietta; Calconi, Gilberto; Bertolone, Gabriele; Gatti, Pierlucio

    2002-01-01

    Anderson-Fabry disease (AFd) is caused by an X-linked inborn error in the glycosphingoLipid metabolic pathway due to an enzymatic defect in a lysosomal hydrolase: alpha-galactosidase A. The defect results in the progressive accumulation of neutral glycosphingolipids in most body fluids and several tissues. The clinical manifestations of AFd are related to organ damage and, obviously, are more severe in hemizygous males than in heterozygous females. In the third decade of life, the course of the disease involves severe deterioration of kidney function progressing to end-stage renal failure. All kind of cells of renal structures are filled with glycosphingolipid deposits. Electron microscopic studies document typical intracytoplasmic osmiophilic bodies with a characteristic "zebra" or "onion-skin" appearance due to concentric lamellation of alternating clear and dark layers. Clinical interest in Fabry patients is related to recent advances in treatment with an intravenous specific enzyme to modify the biochemical error of the glycosphingolipid catabolic pathway. PMID:12018625

  1. Localization in interacting, disordered, Bose systems

    SciTech Connect

    Scalettar, R.T.; Batrouni, G.G.; Zimanyi, G.T. Lawrence Livermore National Laboratory, P.O. Box 808, Livermore, California 94550)

    1991-06-17

    We use quantum Monte Carlo techniques to study a one-dimensional, disordered, interacting, Bose Hamiltonian. The effect of disorder on the Mott-insulator portion of the phase diagram is determined. We observe the destruction of superfluidity by disorder at incommensurate densities, for the first time demonstrating the emergence of a Bose-glass'' phase. In addition to these strong-coupling phases, we observe an unanticipated re-entrance into an Anderson-type localized regime for weak couplings.

  2. The Anderson-Condon-Shortley Site in X-ray Spectroscopies of Solids

    NASA Astrophysics Data System (ADS)

    Delley, Bernard; Uldry, Anne-Christine

    2014-03-01

    Electronic structures of compounds involving open d- and f- shell are studied frequently by X-ray and electron spectroscopies. The excitation, especially core excitation, is localized on a single site makes this the problem of impurity site states interacting with the continuum of bands. on the other hande, the electron-electron interaction whithin the d- or f- shell leads to a multiplet problem as addressed long ago for isolated atoms. Building on our easy to use program multiX (*), which treats an atom in a general crystal field environment without symmetry analysis, we now address the interaction of this atomic entity with the band continuum. The crossover from atomic to bandlike spectra is the focus of interest. We discuss experimental examples where available and accessible to our methods. Swiss SNF grant 200021-129970 is gratefully acknowledged.

  3. Ultrafast optical excitation of magnetic skyrmions.

    PubMed

    Ogawa, N; Seki, S; Tokura, Y

    2015-01-01

    Magnetic skyrmions in an insulating chiral magnet Cu2OSeO3 were studied by all-optical spin wave spectroscopy. The spins in the conical and skyrmion phases were excited by the impulsive magnetic field from the inverse-Faraday effect, and resultant spin dynamics were detected by using time-resolved magneto-optics. Clear dispersions of the helimagnon were observed, which is accompanied by a distinct transition into the skyrmion phase, by sweeping temperature and magnetic field. In addition to the collective excitations of skyrmions, i.e., rotation and breathing modes, several spin precession modes were identified, which would be specific to optical excitation. The ultrafast, nonthermal, and local excitation of the spin systems by photons would lead to the efficient manipulation of nano-magnetic structures. PMID:25897634

  4. Superposition of Fragment Excitations for Excited States of Large Clusters with Application to Helium Clusters.

    PubMed

    Closser, Kristina D; Ge, Qinghui; Mao, Yuezhi; Shao, Yihan; Head-Gordon, Martin

    2015-12-01

    We develop a local excited-state method, based on the configuration interaction singles (CIS) wave function, for large atomic and molecular clusters. This method exploits the properties of absolutely localized molecular orbitals (ALMOs), which strictly limits the total number of excitations, and results in formal scaling with the third power of the system size for computing the full spectrum of ALMO-CIS excited states. The derivation of the equations and design of the algorithm are discussed in detail, with particular emphasis on the computational scaling. Clusters containing ?500 atoms were used in evaluating the scaling, which agrees with the theoretical predictions, and the accuracy of the method is evaluated with respect to standard CIS. A pioneering application to the size dependence of the helium cluster spectrum is also presented for clusters of 25-231 atoms, the largest of which results in the computation of 2310 excited states per sampled cluster geometry. PMID:26609558

  5. Timingbased Mutual Exclusion with Local Spinning # YongJik Kim and James H. Anderson

    E-print Network

    Anderson, James

    on reads, writes, and comparison primitives under the remote­memory­reference (RMR) time measure. Thus, for algorithms in this class, logarithmic or near­logarithmic RMR time complexity is fundamentally required. In this paper, we show that lower RMR time complexity is attainable in semi

  6. Timing-based Mutual Exclusion with Local Spinning Yong-Jik Kim and James H. Anderson

    E-print Network

    Anderson, James

    on reads, writes, and comparison primitives under the remote-memory-reference (RMR) time measure. Thus, for algorithms in this class, logarithmic or near-logarithmic RMR time complexity is fundamentally required. In this paper, we show that lower RMR time complexity is attainable in semi

  7. Asymptotic wave propagation in excitable media.

    PubMed

    Bernus, Olivier; Vigmond, Edward

    2015-07-01

    Wave shape and velocity are important issues in reaction-diffusion systems, and are often the result of competition in media with heterogeneous conduction properties. Asymptotic wave front propagation at maximal conduction velocity has been previously reported in the context of anisotropic cardiac tissue, but it is unknown whether this is a universal property of excitable tissues where conduction velocity can be locally modulated by mechanisms other than anisotropy. Here, we investigate the impact of conduction heterogeneities and boundary effects on wave propagation in excitable media. Following a theoretical analysis, we find that wave-front cusps occur where local velocity is reduced and that asymptotic wave fronts propagate at the maximal translational conduction velocity. Simulations performed in different reaction-diffusion systems, including cardiac tissue, confirm our theoretical findings. We conclude that this property can be found in a wide range of reaction-diffusion systems with excitable dynamics and that asymptotic wave-front shapes can be predicted. PMID:26274110

  8. 8. POWERHOUSE INTERIOR SHOWING EXCITER No. 1 IN FOREGROUND, EXCITER ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    8. POWERHOUSE INTERIOR SHOWING EXCITER No. 1 IN FOREGROUND, EXCITER No. 2., AND GENERATOR UNITS BEHIND EXCITER No. 2 IN BACKGROUND. EXCITER No. 1 GENERATOR HAS A COVER OVER TOP HALF OF COMMUTATOR ELEMENT. VIEW TO NORTHWEST. - Rush Creek Hydroelectric System, Powerhouse Exciters, Rush Creek, June Lake, Mono County, CA

  9. Supersolitons: Solitonic Excitations in Atomic Soliton Chains

    SciTech Connect

    Novoa, David; Michinel, Humberto; Perez-Garcia, Victor M.

    2008-10-03

    We show that, by tuning interactions in nonintegrable vector nonlinear Schroedinger equations modeling Bose-Einstein condensates and other relevant physical systems, it is possible to achieve a regime of elastic particlelike collisions between solitons. This would allow one to construct a Newton's cradle with solitons and supersolitons: localized collective excitations in solitary-wave chains.

  10. Abrupt physical and chemical changes during 1992-1999, Anderson Springs, SE Geyser Geothermal Field, California

    USGS Publications Warehouse

    Janik, Cathy J.; Goff, Fraser; Walter, Stephen R.; Sorey, Michael L.; Counce, Dale; Colvard, Elizabeth M.

    2000-01-01

    The Anderson Springs area is located about 90 miles (145 kilometers) north of San Francisco, California, in the southwestern part of Lake County. The area was first developed in the late 1800s as a health resort, which was active until the 1930s. Patrons drank a variety of cool to hot mineral waters from improved springs, swam in various baths and pools, and hiked in the rugged hills flanking Anderson Creek and its tributaries. In the bluffs to the south of the resort were four small mercury mines of the eastern Mayacmas quicksilver district. About 1,260 flasks of mercury were produced from these mines between 1909 and 1943. By the early 1970s, the higher ridges south and west of Anderson Springs became part of the southeast sector of the greater Geysers geothermal field. Today, several electric power plants are built on these ridges, producing energy from a vapor-dominated 240 °C reservoir. Only the main hot spring at Anderson Springs has maintained a recognizable identity since the 1930s. The hot spring is actually a cluster of seeps and springs that issue from a small fault in a ravine southwest of Anderson Creek. Published and unpublished records show that the maximum temperature (Tm) of this cluster fell gradually from 63°C in 1889 to 48°C in 1992. However, Tm of the cluster climbed to 77°C in 1995 and neared boiling (98°C) in 1998. A new cluster of boiling vents and small fumaroles (Tm = 99.3°C) formed in 1998 about 30 m north of the old spring cluster. Several evergreen trees on steep slopes immediately above these vents apparently were killed by the new activity. Thermal waters at Anderson Hot Springs are mostly composed of near-surface ground waters with some added gases and condensed steam from The Geysers geothermal system. Compared to gas samples from Southeast Geysers wells, the hot spring gases are higher in CO2 and lower in H2S and NH3. As the springs increased in temperature, however, the gas composition became more like the mean composition of steam discharges from the Southeast Geysers. The hot spring waters are low in ions of Cl, B, and Li, but relatively high in HCO3, SO4 and NH4. The stable-isotope compositions (deuterium and oxygen-18) of these waters plot near the global meteoric water line. Geochemical data through time reveal apparent maxima in the concentrations of SO4, Fe, and Mn in 1991 to 1992, before the cluster became hotter. The black-to-gray deposits from the new spring cluster are rich in pyrite and contain anomalous metals. About one-half mile to the east of the hot springs, mineralized water discharges intermittently from an old adit of the Schwartz (Anderson) mine, and enters a tributary of Anderson Creek. This drainage increased substantially in July 1998, and a slurry of mine water and precipitates were transported down the tributary and into Anderson Creek. In December 1998, the adit water was 22°C, and had a chemical composition that was similar to spring waters that once discharged in the ravines surrounding the old Anderson Springs resort. The cause for the abrupt changes that have occurred in thermal features at Anderson Springs is still not resolved. One possibility is that these changes are a response to withdrawal of steam from The Geysers geothermal field over more than 20 years of production. Pressure declines in the geothermal reservoir may have caused a "drying out" of the overlying condensation zone. Induced boiling in this zone and upflow of deep steam to shallower depths would cause heating and vaporization of shallow ground waters. In addition, earthquakes occurring in the vicinity of Anderson Springs have increased significantly after nearby geothermal power plants began operation. These earthquakes may have enhanced surface discharge of thermal fluids along fractures and faults.

  11. R. SCHUMANNand K. ELK:Thermal Conductivity of the Periodic Anderson Model 221 phys. stat. sol. (b)119, 221 (1983)

    E-print Network

    Schumann, Rolf

    1983-01-01

    R. SCHUMANNand K. ELK:Thermal Conductivity of the Periodic Anderson Model 221 phys. stat. sol. (b BY It.SCHUMANNand K. ELK The periodic Anderson model is used as a simple niodel describing intermediate.SGHUMANNand K. ELK Then the thermopower X is given by and the thermal conductivity ~tfollows from I n

  12. Quantum computation of the Anderson transition in the presence of imperfections A. A. Pomeransky and D. L. Shepelyansky*

    E-print Network

    Shepelyansky, Dima

    Quantum computation of the Anderson transition in the presence of imperfections A. A. Pomeransky sensitivity to static imperfections in a quantum computer. In the vicinity of the critical point the algorithm to the known classical algorithms. We show that the Anderson transition can be detected on quantum computers

  13. Collective excitations in solids

    SciTech Connect

    Di Bartolo, B.

    1983-01-01

    This book is based on the NATO Advanced Study Institute on ''Collective Excitations in Solids'' held in Italy in 1981. The objective of the Institute was to formulate a unified and coherent treatment of various collective excitation processes by drawing on the current advances in various branches of the physics of the solid state. Topics include the quantum mechanical description of solids; an introduction to collective excitations in solids; quasi-particles and excitons (models of structure and correlation); coherent wavepackets of phonons; an introduction to exciton physics; excitons in semiconductors; excitons in insulators; inelastic scattering of fast particles by plasmons; from magnons to solitons; quasiparticles in magnetic metals; polaritons; polarons; surface collective excitations; collective excitations in concentrated Mn/sup 2 +/ systems (spectral properties); optical dynamics in concentrated Mn/sup 2 +/ systems; spectroscopy of stoichiometric laser materials (excitons or incoherent transfers.); exciton-hole droplets in semiconductors; excitons and plasmons (collective excitations in semiconductors); picosecond exciton phenomena in chlorophyll complexes; and present trends in collective excitations in solids.

  14. Excitability dependent pattern formation

    NASA Astrophysics Data System (ADS)

    Prabhakara, Kaumudi; Gholami, Azam; Bodenschatz, Eberhard

    2014-03-01

    On starvation, the amoebae Dictyostelium discoideum emit the chemo-attractant cyclic adenosine monophosphate (cAMP) at specific frequencies. The neighboring amoebae sense cAMP through membrane receptors and produce their own cAMP. Soon the cells synchronize and move via chemotaxis along the gradient of cAMP. The response of the amoebae to the emission of cAMP is seen as spiral waves or target patterns under a dark field microscope. The causal reasons for the selection of one or the other patterns are still unclear. Here we present a possible explanation based on excitability. The excitability of the amoebae depends on the starvation time because the gene expression changes with starvation. Cells starved for longer times are more excitable. In this work, we mix cells of different excitabilities to study the dependence of the emergent patterns on the excitability. Preliminary results show a transition from spirals to target patterns for specific excitabilities. A phase map of the patterns for different combinations of excitability and number densities is obtained. We compare our findings with numerical simulations of existing theoretical models.

  15. Excitable solitons in a semiconductor laser with a saturable absorber

    NASA Astrophysics Data System (ADS)

    Turconi, Margherita; Prati, Franco; Barland, Stéphane; Tissoni, Giovanna

    2015-11-01

    Self-pulsing cavity solitons may exist in a semiconductor laser with an intracavity saturable absorber. They show locally the passive Q -switching behavior that is typical of lasers with saturable absorbers in the plane-wave approximation. Here we show that excitable cavity solitons are also possible in a suitable parameter range and characterize their excitable dynamics and properties.

  16. Main-Chain Conformational Tendencies of Amino Acids Robert J. Anderson,1,2

    E-print Network

    Weng, Zhiping

    Main-Chain Conformational Tendencies of Amino Acids Robert J. Anderson,1,2 Zhiping Weng,2 Robert K tendencies of an amino acid. Despite forty years of research, the shape of Ramachandran plots is still tendencies among amino acids, and showed that the conformational relationships of amino ac- ids are well

  17. Potential energy surface for the hydrogen-iodine reaction James B. Anderson

    E-print Network

    Anderson, James B.

    Potential energy surface for the hydrogen-iodine reaction James B. Anderson Department of Chemistry valenceelectronsand with effectivepotentials for the iodine core electrons.The favored pathway for the overall-H-H-I. The pathway is accessibleto bound and unbound iodine atom pairs and it allows the bimolecular and termolecular

  18. 78 FR 41835 - Inflation Adjustments to the Price-Anderson Act Financial Protection Regulations

    Federal Register 2010, 2011, 2012, 2013, 2014

    2013-07-12

    ... operate a combination of 2 or more nuclear reactors located at a single site, each of which has a rated... made the initial changes to the Price-Anderson Act amounts on October 27, 2005 (70 FR 61885), and the first periodic inflation adjustments on September 29, 2008 (73 FR 56451). This final rule makes...

  19. Tor Instead of IP Vincent Liu, Seungyeop Han, Arvind Krishnamurthy, Thomas Anderson

    E-print Network

    Anderson, Tom

    Tor Instead of IP Vincent Liu, Seungyeop Han, Arvind Krishnamurthy, Thomas Anderson University, and denial of service. Al- though anonymizing overlays such as Tor [2] provide some help to end users approach: instead of running Tor on top of IP, we propose to run Tor instead of IP. We ask: what might

  20. AUTO ANSWER CIRCUIT DESIGN FOR AN ANDERSON JACOBSON AD 342 MODEM

    EPA Science Inventory

    The report describes a circuit which connects a Western Electric Model 1001F Data Accessing Arrangement to an Anderson Jacobson Model AD 342 Modem. It automatically answers the phone and holds a data connection as long as a received carrier is present. It self resets upon loss of...

  1. Understanding Diagrammatic Ink in Lecture Richard Anderson, Crystal Hoyer, Craig Prince,

    E-print Network

    Anderson, Richard

    Understanding Diagrammatic Ink in Lecture Richard Anderson, Crystal Hoyer, Craig Prince, Jonathan We are interested in understanding how digital ink and speech are used together in presentation. Our long range goal is to develop tools to analyze the ink and speech channels of recorded lectures

  2. 54. August 18, 1939 Oakland, California A.E. Anderson Taken during ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    54. August 18, 1939 Oakland, California A.E. Anderson Taken during trials on San Fransico Bay. Photograph taken for the U.S. Lighthouse Service. Currently in collection at Columbia River Maritime Museum. (Negative #67-133.3) - U.S. Coast Guard Cutter FIR, Puget Sound Area, Seattle, King County, WA

  3. Bio390 Glucose and the Kidney ANSWERS thanks to Dr. J.F. Anderson,

    E-print Network

    Prestwich, Ken

    1 Bio390 Glucose and the Kidney ANSWERS thanks to Dr. J.F. Anderson, Dept Zoology Univ of Florida of urine formation: 1.0 ml min plasma glucose concentration: 80 mg 100 ml plasma urine glucose concentration: 0 mg ml CALCULATE: the reabsorption rate for glucose ANS: 100 mg glucose / min Since glucose

  4. Quantum vacuum instability of "eternal" de Sitter space Paul R. Anderson*

    E-print Network

    Anderson, Paul R.

    Quantum vacuum instability of "eternal" de Sitter space Paul R. Anderson* Department of Physics invariant one is constructed, which is also not a stable vacuum state under perturbations. The role by quantum fluctuations. Potential consequences of this result for cosmology and the problem of vacuum energy

  5. The effects of interannual climate variability on the moraine"! Leif S. Anderson1

    E-print Network

    Anderson, Robert S.

    ! "! The effects of interannual climate variability on the moraine"! record#! Leif S. Anderson1(! ABSTRACT)! Glacial moraines are commonly used to infer mean climate conditions (annual*! precipitation and melt-season temperature) at the time of moraine formation. However, recent"+! research has demonstrated

  6. Bio390 Problem: Gas Laws thanks to Dr. J.F. Anderson,

    E-print Network

    Prestwich, Ken

    Bio390 Problem: Gas Laws thanks to Dr. J.F. Anderson, Dept. Zoology Univ. of Florida, Gainesville atmosphere has the following composition, all on a dry gas basis: (a) oxygen = 70%; (b) carbon dioxide = 3 the percent concentration on a dry gas basis and the partial pressure of each gas in the chamber atmosphere

  7. Generation of the S boxes of Tiger Ross Anderson 1 and Eli Biham 2

    E-print Network

    Biham, Eli

    Generation of the S boxes of Tiger Ross Anderson 1 and Eli Biham 2 1 Cambridge University, England algorithm of the S boxes of Tiger uses the compression func­ tion of Tiger in order to achieve random the S boxes to the unity columns, and the state to the initial value of the state of Tiger. Then it randomizes

  8. On the Stability of Web Crawling and Web Reid Anderson1

    E-print Network

    Borgs, Christian

    On the Stability of Web Crawling and Web Search Reid Anderson1 , Christian Borgs1 , Jennifer Chayes moti- vated by web crawling. We introduce a notion of stable cores, which is the set of web pages that are usually contained in the crawling buffer when the buffer size is smaller than the total number of web

  9. An Expressive Text-Driven 3D Talking Head Robert Anderson1

    E-print Network

    Cipolla, Roberto

    An Expressive Text-Driven 3D Talking Head Robert Anderson1 , Bj¨orn Stenger2 , Vincent Wan2 Introduction Creating a realistic talking head, which given an arbitrary text as input generates a realistic looking face speaking the text, has been a long standing research challenge. Talking heads which cannot

  10. Publications for Xiaohui Sun Sun, X., Rudnick, L., Akahori, T., Anderson, C., Bell, M., Bray,

    E-print Network

    Müller, Dietmar

    Publications for Xiaohui Sun 2015 Sun, X., Rudnick, L., Akahori, T., Anderson, C., Bell, M., Bray Reich, W., Sun, X., Reich, P., Gao, X., Xiao, L., Han, J. (2014). A Sino-German λ6 cm polarisation-10. [More Information] Sun, X., Gaensler, B

  11. CONFORMAL IMMERSIONS OF PRESCRIBED MEAN CURVATURE IN R 3 MICHAEL T. ANDERSON

    E-print Network

    Anderson, Michael

    CONFORMAL IMMERSIONS OF PRESCRIBED MEAN CURVATURE IN R 3 MICHAEL T. ANDERSON Abstract. We prove the existence of (branched) conformal immersions F : S 2 # R 3 with mean curvature H > 0 arbitrarily prescribed and partial results for surfaces of higher genus. 1. Introduction Consider an immersed closed surface F

  12. CONFORMAL IMMERSIONS OF PRESCRIBED MEAN CURVATURE IN R3 MICHAEL T. ANDERSON

    E-print Network

    Anderson, Michael

    CONFORMAL IMMERSIONS OF PRESCRIBED MEAN CURVATURE IN R3 MICHAEL T. ANDERSON Abstract. We prove the existence of (branched) conformal immersions F : S2 R3 with mean curvature H > 0 arbitrarily prescribed up and partial results for surfaces of higher genus. 1. Introduction Consider an immersed closed surface F : S R

  13. Einstein/MMC CFAR Awarded Pilot Projects for 2006 Dr. Matthew Anderson, Department of

    E-print Network

    Emmons, Scott

    Einstein/MMC CFAR Awarded Pilot Projects for 2006 PI Title Dr. Matthew Anderson, Department retention of gp160 Einstein/MMC CFAR Awarded Pilot Projects for 2005 PI Title Dr. Carol Harris, Department Einstein/MMC CFAR Awarded Pilot Projects for 2004 PI Title Dr. Laura Santambrogio, Department of Pathology

  14. Thomas Young's research on fluid transients: 200 years on Arris S Tijsseling Alexander Anderson

    E-print Network

    Eindhoven, Technische Universiteit

    1 Thomas Young's research on fluid transients: 200 years on Arris S Tijsseling Alexander Anderson The Netherlands United Kingdom ABSTRACT Thomas Young published in 1808 his famous paper (1) in which he derived, solid transients, wave speed, history, Thomas Young NOTATION c sonic wave speed, m/s D internal tube

  15. LEGO MindStorms: Not Just for K-12 Anymore Frank Klassner, Scott D. Anderson

    E-print Network

    Klassner, Frank

    the possibility of using the Lego Mindstorms robots to support the ACM Computing Curriculum 2001, using them 2001, curriculum development, robotics, Lego Mindstorms Introduction The fields of RoboticsLEGO MindStorms: Not Just for K-12 Anymore Frank Klassner, Scott D. Anderson Department

  16. Melissa L. Anderson: APA/APAGS Award for Distinguished Graduate Student in Professional Psychology

    ERIC Educational Resources Information Center

    American Psychologist, 2012

    2012-01-01

    Presents a short biography of the winner of the American Psychological Association/American Psychological Association of Graduate Students Award for Distinguished Graduate Student in Professional Psychology. The 2012 winner is Melissa L. Anderson for her ongoing commitment to understanding, treating, and preventing domestic violence in Deaf women…

  17. Quartz: A Tool for Tuning Parallel Program Performance Thomas E. Anderson andEdward D. Lazowska

    E-print Network

    Anderson, Tom

    Quartz: A Tool for Tuning Parallel Program Performance Thomas E. Anderson andEdward D. Lazowska on the quality of the instrumentation that is available to the programmer. This paper describes Quartz, a new underlying Quartz was inspired by that of the sequential UNIX tool gprof: to appropriately direct

  18. Polar Sea Ice Mapping Using SeaWinds Data Hyrum S. Anderson and David G. Long

    E-print Network

    Long, David G.

    Polar Sea Ice Mapping Using SeaWinds Data Hyrum S. Anderson and David G. Long Brigham Young for mapping polar sea ice extent. In this study, a new al- gorithm for polar sea ice mapping is developed for use with the SeaWinds instrument. The approach utilizes a priori information within the framework

  19. Serial exploitation of global sea cucumber fisheries Sean C Anderson1

    E-print Network

    Myers, Ransom A.

    Serial exploitation of global sea cucumber fisheries Sean C Anderson1 , Joanna Mills Flemming2 trajectory of sea cucumber fisheries 5 Drivers of sea cucumber fisheries 6 Rate of development 8 Distance in catch and value worldwide. One increasingly harvested group is sea cucumbers (class Holothuroidea

  20. Lamport on Mutual Exclusion: 27 Years of Planting Seeds James H. Anderson

    E-print Network

    Anderson, James

    Lamport on Mutual Exclusion: 27 Years of Planting Seeds James H. Anderson Department of Computer Science University of North Carolina at Chapel Hill Abstract Mutual exclusion is a topic that Leslie on the mutual exclusion problem than any other single researcher. In this survey article, I describe some of his

  1. Natural Decompositions of Perceived Transparency: Reply to Albert (2008) Barton L. Anderson

    E-print Network

    Singh, Manish

    2008-01-01

    Natural Decompositions of Perceived Transparency: Reply to Albert (2008) Barton L. Anderson proposed a model based on ratios of Michelson contrasts to explain how human observers quantitatively scale general model based on ratios of perceived contrasts. M. K. Albert's (2008) main experiment aimed to test

  2. Lifshitz tails estimate for the density of states of the Anderson model

    E-print Network

    Jean-Michel Combes; Fran\\c cois Germinet; Abel Klein

    2010-08-27

    We prove an upper bound for the (differentiated) density of states of the Anderson model at the bottom of the spectrum. The density of states is shown to exhibit the same Lifshitz tails upper bound as the integrated density of states.

  3. PDF tails and self-organization of shear flows Johan Anderson

    E-print Network

    PDF tails and self-organization of shear flows Johan Anderson Department of Applied Mathematics and motivation · Goal: To find the generic analytical expression for the PDF tails. · The tails are often close to Gaussian but reveals a significant deviation from Gaussianity at the tails (intermittency

  4. Replacement of the Green Bank Telescope azimuth track Robert Anderson*, Arthur Symmes, Dennis Egan

    E-print Network

    Groppi, Christopher

    of the Green Bank Telescope did not perform as designed. Relative movement of components was noted duringReplacement of the Green Bank Telescope azimuth track Robert Anderson*, Arthur Symmes, Dennis Egan National Radio Astronomy Observatory (NRAO) P.O. Box 2, Green Bank, WV USA 24944 ABSTRACT The azimuth track

  5. Wildlife Protection, Mitigation, and Enhancement Plans, Anderson Ranch and Black Canyon Facilities: Final Report.

    SciTech Connect

    Meuleman, G. Allyn

    1987-06-01

    Under direction of the Pacific Northwest Electric Power Planning and Conservation Act of 1980, and the subsequent Northwest Power Planning Council's Columbia River Basin Fish and Wildlife Program, projects have been developed in Idaho to mitigate the impacts to wildlife habitat and production due to the development and operation of the Anderson Ranch and Black Canyon Facilities (i.e., dam, power plant, and reservoir areas). The Anderson Ranch Facility covered about 4812 acres of wildlife habitat while the Black Canyon Facility covered about 1115 acres. These acreages include dam and power plant staging areas. A separate mitigation plan has been developed for each facility. A modified Habitat Evaluation Procedure (HEP) was used to assess the benefits of the mitigation plans to wildlife. The interagency work group used the target species Habitat Units (HU's) lost at each facility as a guideline during the mitigation planning process, while considering the needs of wildlife in the areas. Totals of 9619 and 2238 target species HU's were estimated to be lost in the Anderson Ranch and Black Canyon Facility areas, respectively. Through a series of projects, the mitigation plans will provide benefits of 9620 target species HU's to replace Anderson Ranch wildlife impacts and benefits of 2195 target species HU's to replace Black Canyon wildlife impacts. Target species to be benefited by the Anderson Ranch and/or Black Canyon mitigation plans include the mallard, Canada goose, mink, yellow warbler, black-capped chickadee, ruffed grouse, mule deer, blue grouse, sharp-tailed grouse, ring-necked pheasant, and peregrine falcon.

  6. Shear layer excitation, experiment versus theory

    NASA Technical Reports Server (NTRS)

    Bechert, D. W.; Stahl, B.

    1984-01-01

    The acoustical excitation of shear layers is investigated. Acoustical excitation causes the so-called orderly structures in shear layers and jets. Also, the deviations in the spreading rate between different shear layer experiments are due to the same excitation mechanism. Measurements in the linear interaction region close to the edge from which the shear layer is shed are examined. Two sets of experiments (Houston 1981 and Berlin 1983/84) are discussed. The measurements were carried out with shear layers in air using hot wire anemometers and microphones. The agreement between these measurements and the theory is good. Even details of the fluctuating flow field correspond to theoretical predictions, such as the local occurrence of negative phase speeds.

  7. Nanoscale control of phonon excitations in graphene

    PubMed Central

    Kim, Hyo Won; Ko, Wonhee; Ku, JiYeon; Jeon, Insu; Kim, Donggyu; Kwon, Hyeokshin; Oh, Youngtek; Ryu, Seunghwa; Kuk, Young; Hwang, Sung Woo; Suh, Hwansoo

    2015-01-01

    Phonons, which are collective excitations in a lattice of atoms or molecules, play a major role in determining various physical properties of condensed matter, such as thermal and electrical conductivities. In particular, phonons in graphene interact strongly with electrons; however, unlike in usual metals, these interactions between phonons and massless Dirac fermions appear to mirror the rather complicated physics of those between light and relativistic electrons. Therefore, a fundamental understanding of the underlying physics through systematic studies of phonon interactions and excitations in graphene is crucial for realising graphene-based devices. In this study, we demonstrate that the local phonon properties of graphene can be controlled at the nanoscale by tuning the interaction strength between graphene and an underlying Pt substrate. Using scanning probe methods, we determine that the reduced interaction due to embedded Ar atoms facilitates electron–phonon excitations, further influencing phonon-assisted inelastic electron tunnelling. PMID:26109454

  8. Excitation Methods for Bridge Structures

    SciTech Connect

    Farrar, C.R.; Duffy, T.A.; Cornwell, P.J.; Doebling, S.W.

    1999-02-08

    This paper summarizes the various methods that have been used to excited bridge structures during dynamic testing. The excitation methods fall into the general categories of ambient excitation methods and measured-input excitation methods. During ambient excitation the input to the bridge is not directly measured. In contrast, as the category label implies, measured-input excitations are usually applied at a single location where the force input to the structure can be monitored. Issues associated with using these various types of measurements are discussed along with a general description of the various excitation methods.

  9. Quantum criticality in the pseudogap Bose-Fermi Anderson and Kondo models: Interplay between fermion- and boson-induced Kondo destruction

    NASA Astrophysics Data System (ADS)

    Pixley, J. H.; Kirchner, Stefan; Ingersent, Kevin; Si, Qimiao

    2013-12-01

    We address the phenomenon of critical Kondo destruction in pseudogap Bose-Fermi Anderson and Kondo quantum impurity models. These models describe a localized level coupled both to a fermionic bath having a density of states that vanishes like |?|r at the Fermi energy (?=0) and, via one component of the impurity spin, to a bosonic bath having a sub-Ohmic spectral density proportional to |?|s. Each bath is capable by itself of suppressing the Kondo effect at a continuous quantum phase transition. We study the interplay between these two mechanisms for Kondo destruction using continuous-time quantum Monte Carlo for the pseudogap Bose-Fermi Anderson model with 0localized (Kondo-destroyed) phase. The two solution methods, which are in good agreement in their domain of overlap, provide access to the many-body spectrum, as well as to correlation functions including, in particular, the single-particle Green's function and the static and dynamical local spin susceptibilities. The quantum-critical regime exhibits the hyperscaling of critical exponents and ?/T scaling in the dynamics that characterize an interacting critical point. The (r,s) plane can be divided into three regions: one each in which the calculated critical properties are dominated by the bosonic bath alone or by the fermionic bath alone, and between these two regions, a third in which the bosonic bath governs the critical spin response but both baths influence the renormalization-group flow near the quantum-critical point.

  10. Excitations Propagating Along Surfaces

    E-print Network

    A. V. Stoyanovsky

    2006-05-22

    A number of equations is deduced which describe propagation of excitations along $n$-dimensional surfaces in $R^N$. Usual excitations in wave theory propagate along 1-dimensional trajectories. The role of the medium of propagation of excitations considered in this paper is played by the infinite dimensional space of $(n-1)$-dimensional surfaces in $R^N$. The role of rays is played by $n$-dimensional solution surfaces of the variational problem. Such a generalization of wave theory can be useful in quantum field theory. Among these equations are the generalized Hamilton--Jacobi equation (known in particular cases in the literature), generalized canonical Hamilton equations, and generalized Schrodinger equation. Besides that, a theory of integration of the generalized Hamilton--Jacobi equation is developed.

  11. Entanglement in the many-body localized phase and transition

    NASA Astrophysics Data System (ADS)

    Bardarson, Jens H.

    2015-03-01

    The study of entanglement, both in eigenstates and its evolution after quenches, has been instrumental in advancing our understanding of many-body localized phases--the interacting analogs of the Anderson insulator. In this talk I will discuss in detail three observations related to the entanglement properties of many-body localized systems: (i) A global quench within the many-body localized phase gives rise to a slowly (logarithmically) increasing entanglement entropy. This is due to interaction induced dephasing that is absent in the Anderson insulator and therefore serves as a unique signature of the many-body localized phase. (ii) A local quench from an eigenstate leads to an extensive increase in the entanglement entropy only at the many-body localization transition itself. And (iii) at the many-body localization transition the distribution of entanglement entropies becomes extensively broad, while it vanishes both in the extended metallic phase and in the localized phases. The width of the entanglement distribution, like the long time limit of the local quench, is therefore a useful diagnostic for a many-body localization transition. I explicitly demonstrate how all these features are observed in microscopic spin chain models of many-body localization, and, in particular, discuss how they can be used to detect a many-body mobility edge.

  12. Long-range excitations in time-dependent density functional theory Neepa T. Maitraa

    E-print Network

    Long-range excitations in time-dependent density functional theory Neepa T. Maitraa and David G Adiabatic time-dependent density functional theory fails for excitations of a heteroatomic molecule composed-correlation kernel is necessary for both local and charge-transfer excitations. The root of this is the static

  13. Modeling collective excitations in cortical tissue

    NASA Astrophysics Data System (ADS)

    Kistler, Werner M.; Seitz, Richard; van Hemmen,, J. Leo

    1998-04-01

    We study a two-dimensional system of spiking neurons with local interactions depending on distance. The interactions between the neurons decrease as the distance between them increases and can be either excitatory or inhibitory. Depending on the mix of excitation and inhibition, this kind of system exhibits a rich repertoire of collective excitations such as traveling waves, expanding rings, and rotating spirals. We present a continuum approximation that allows an analytic treatment of plane waves and circular rings. We calculate the dispersion relation for plane waves and perform a linear stability analysis. Only waves that have a speed of propagation below a certain critical velocity, are stable. For target patterns, we derive an integro-differential equation that describes the evolution of a circular excitation. Its asymptotic behavior is handled exactly. We illustrate the analytic results by parallel-computer simulations of a network of 10 6 neurons. In so doing, we exhibit a novel type of local excitation, a so-called ‘paternoster’.

  14. Dynamical Localization in Kicked Quantum Rotors

    NASA Astrophysics Data System (ADS)

    Kamalov, Andrei; Broege, Douglas; Bucksbaum, Philip H.

    2015-05-01

    The quantum periodically ?-kicked rotor has been shown to experience localization within angular momentum space, rotational wavepacket amplification or annihilation, and Bloch oscillations, amongst other effects, depending on the choice of time-separation between individual kicks. Localization within rotation state space has been linked to Anderson localization within 1-D chains, and has been extensively studied with calculations. Previous experiments used cold atoms in optical lattices to measure a related localization phenomenon. We utilize a train of eight femtosecond scale pulses and compare the molecular alignment signal of a true quantum linear rotor at room temperature when it is kicked periodically and aperiodically. Our data is the first observation of the much studied dynamical localization phenomenon within the quantum rotor. Supported through the Stanford PULSE Institute at the SLAC National Accelerator Laboratory by the U.S. Department of Energy, Office of Basic Energy Sciences.

  15. Positron excitation of neon

    NASA Technical Reports Server (NTRS)

    Parcell, L. A.; Mceachran, R. P.; Stauffer, A. D.

    1990-01-01

    The differential and total cross section for the excitation of the 3s1P10 and 3p1P1 states of neon by positron impact were calculated using a distorted-wave approximation. The results agree well with experimental conclusions.

  16. Exploring Excited Hadrons

    E-print Network

    Colin Morningstar

    2008-10-24

    Progress in extracting the spectrum of excited hadron resonances is reviewed and the key issues and challenges in such computations are outlined. The importance of multi-hadron states as simulations are done with lighter pion masses is discussed, and the need for all-to-all quark propagators is emphasized.

  17. Localization, delocalization, and topological phase transitions in the one-dimensional split-step quantum walk

    NASA Astrophysics Data System (ADS)

    Rakovszky, Tibor; Asboth, Janos K.

    2015-11-01

    Quantum walks are promising for information processing tasks because in regular graphs they spread quadratically more rapidly than random walks. Static disorder, however, can turn the tables: unlike random walks, quantum walks can suffer Anderson localization, with their wave function staying within a finite region even in the infinite time limit, with a probability exponentially close to 1. It is thus important to understand when a quantum walk will be Anderson localized and when we can expect it to spread to infinity even in the presence of disorder. In this work we analyze the response of a one-dimensional quantum walk—the split-step walk—to different forms of static disorder. We find that introducing static, symmetry-preserving disorder in the parameters of the walk leads to Anderson localization. In the completely disordered limit, however, a delocalization transition occurs, and the walk spreads subdiffusively to infinity. Using an efficient numerical algorithm, we calculate the bulk topological invariants of the disordered walk and find that the disorder-induced Anderson localization and delocalization transitions are governed by the topological phases of the quantum walk.

  18. On the Aggregation of Local Risk Models for Global Risk Management

    E-print Network

    On the Aggregation of Local Risk Models for Global Risk Management Greg Anderson Vice President: portfolio risk, total risk, optimization, positive definite. 2 #12;1 Introduction Portfolio managers of markets, e.g. equities within various different countries. Each portfolio manager will have her own

  19. Anderson transition in ultracold atoms: Signatures and experimental feasibility

    SciTech Connect

    Garcia-Garcia, Antonio M.; Wang Jiao

    2006-12-15

    Kicked rotators with certain nonanalytic potentials avoid dynamical localization and undergo a metal-insulator transition. We show that typical properties of this transition are still present as the nonanalyticity is progressively smoothed out provided that the smoothing is less than a certain limiting value. We have identified a smoothing-dependent time scale such that full dynamical localization is absent and the quantum momentum distribution develops power-law tails with anomalous decay exponents as in the case of a conductor at the metal-insulator transition. We discuss under what conditions these findings may be verified experimentally by using ultracold atom techniques. It is found that ultracold atoms can indeed be utilized for the experimental investigation of the metal-insulator transition.

  20. Vacuum excitation by sudden (dis-)appearance of a Dirichlet wall in a cavity

    E-print Network

    Harada, Tomohiro; Miyamoto, Umpei

    2016-01-01

    Vacuum excitation by time-varying boundary conditions is not only of fundamental importance but also has recently been confirmed in a laboratory experiment. In this paper, we study the vacuum excitation of a scalar field by the instantaneous appearance and disappearance of a both-sided Dirichlet wall in the middle of a 1D cavity, as toy models of bifurcating and merging spacetimes, respectively. It is shown that the energy flux emitted positively diverges on the null lines emanating from the (dis-)appearance event, which is analogous to the result of Anderson and DeWitt. This result suggests that the semiclassical effect prevents the spacetime both from bifurcating and merging. In addition, we argue that the diverging flux in the disappearance case plays an interesting role to compensate for the lowness of ambient energy density after the disappearance, which is lower than the zero-point level.

  1. 77 FR 72906 - Chessie Logistics Co., LLC-Acquisition and Operation Exemption-J. Emil Anderson & Son, Inc.

    Federal Register 2010, 2011, 2012, 2013, 2014

    2012-12-06

    ...Docket No. FD 35700] Chessie Logistics Co., LLC--Acquisition...Anderson & Son, Inc. Chessie Logistics Co., LLC (Chessie), a...proceeding, Mannheim Armitage Railway, LLC (Mannheim), a wholly...Legal Counsel, Chessie Logistics Co., LLC, 1001 Green...

  2. 10 CFR 8.2 - Interpretation of Price-Anderson Act, section 170 of the Atomic Energy Act of 1954.

    Code of Federal Regulations, 2012 CFR

    2012-01-01

    ...Price-Anderson Act, section 170 of the Atomic Energy Act of 1954. 8.2 Section 8.2 Energy NUCLEAR REGULATORY COMMISSION INTERPRETATIONS...Insurance, in Law and Administration in Nuclear Energy 75 (1959). In the testimony...

  3. GPUSync: A Framework for Real-Time GPU Management Glenn A. Elliott, Bryan C. Ward, and James H. Anderson

    E-print Network

    Anderson, James

    GPUSync: A Framework for Real-Time GPU Management Glenn A. Elliott, Bryan C. Ward, and James H. Anderson Department of Computer Science, University of North Carolina at Chapel Hill Abstract This paper

  4. Universal scaling of nonlinear conductance in the two-channel pseudogap Anderson model: Application for gate-tuned Kondo effect in magnetically doped graphene

    NASA Astrophysics Data System (ADS)

    Lee, Tsung-Han; Zhang, Kenneth Yi-Jie; Chung, Chung-Hou; Kirchner, Stefan

    2013-08-01

    Based on the noncrossing approximation, we calculate both the linear and nonlinear conductance within the two-lead two-channel single-impurity Anderson model where the conduction electron density of states vanishes in a power-law fashion ?|?-?F|r with r=1 near the Fermi energy, appropriate for a hexagonal system. For given gate voltage, we address the universal crossover from a two-channel Kondo phase, argued to occur in doped graphene, to an unscreened local moment phase. We extract universal scaling functions in conductance governing charge transfer through the two-channel pseudogap Kondo impurity and discuss our results in the context of a recent scanning tunneling spectroscopy experiment on Co-doped graphene.

  5. Anderson's impurity-model analysis on CeO1-xFxBiS2

    NASA Astrophysics Data System (ADS)

    Sugimoto, Takuya; Joseph, Boby; Paris, Eugenio; Iadecola, Antonella; Demura, Satoshi; Mizuguchi, Yoshikazu; Takano, Yoshihiko; Mizokawa, Takashi; Saini, Naurang L.

    2015-03-01

    We have investigated the impact of F-doing on CeO1-xFxBiS2 in terms of the electronic-structural parameters of Anderson's impurity-model analysis. It was recently reported using Ce L3-edge x-ray absorption spectroscopy (XAS) that CeOBiS2 falls in the Ce valence fluctuation regime and the F-doping drives the system into the Kondo regime. The Ce L3- edge XAS spectra with the various F-doping levels can be reproduced by adjusting the transfer integral in the Anderson's impurity model. The present analysis indicates that the F-doping to the system corresponds to the decrease of the Ce-Bi transfer integral.

  6. Ferromagnetic instability in a mean-field slave-boson approach for the Anderson lattice

    SciTech Connect

    Dorin, V.; Schlottmann, P. )

    1993-05-15

    We consider a stoichiometric metallic Anderson lattice with orbital degeneracy in the [ital U][r arrow][infinity] limit. A Gutzwiller type of mean-field approximation is formulated in terms of three slave bosons per site in analogy to Kotliar and Ruckenstein's approach for the Hubbard model. In the orbitally nondegenerate case the paramagnetic solution becomes unstable towards ferromagnetism if the valence is smaller than a critical one. This instability is suppressed with increasing orbital degeneracy.

  7. Magnetic frustration in the three-band Anderson lattice model for high-temperature superconductors

    SciTech Connect

    Ihle, D.; Kasner, M. )

    1990-09-01

    The three-band Anderson lattice model for the CuO{sub 2} planes in high-{Tc} superconductors is established. Treating this model by perturbation theory, the effective spin interactions are derived. The antiferromagnetic superexchange integrals are calculated as functions of the direct oxygen transfer and the hole concentration. It is found that frustration in the superexchange occurs, even in the undoped case, which increases with oxygen trnasfer and decreases with hole concentration.

  8. Electronic structure of vitamin B12 within the framework of the Haldane-Anderson impurity model

    NASA Astrophysics Data System (ADS)

    Kandemir, Zafer; Mayda, Selma; Bulut, Nejat

    2015-03-01

    We study the electronic structure of vitamin B12 (cyanocobalamine C63H88CoN14O14P) by using the framework of the multi-orbital single-impurity Haldane-Anderson model of a transition-metal impurity in a semiconductor host. Here, our purpose is to understand the many-body effects originating from the transition-metal impurity. In this approach, the cobalt 3 d orbitals are treated as the impurity states placed in a semiconductor host which consists of the rest of the molecule. The parameters of the resulting effective Haldane-Anderson model are obtained within the Hartree-Fock approximation for the electronic structure of the molecule. The quantum Monte Carlo technique is then used to calculate the one-electron and magnetic correlation functions of this effective Haldane-Anderson model for vitamin B12. We find that new states form inside the semiconductor gap due to the on-site Coulomb interaction at the impurity 3 d orbitals and that these states become the highest occupied molecular orbitals. In addition, we present results on the charge distribution and spin correlations around the Co atom. We compare the results of this approach with those obtained by the density-functional theory calculations.

  9. Magnetostrictive resonance excitation

    DOEpatents

    Schwarz, Ricardo B. (Los Alamos, NM); Kuokkala, Veli-Tapani (Tampere, FI)

    1992-01-01

    The resonance frequency spectrum of a magnetostrictive sample is remotely determined by exciting the magnetostrictive property with an oscillating magnetic field. The permeability of a magnetostrictive material and concomitant coupling with a detection coil varies with the strain in the material whereby resonance responses of the sample can be readily detected. A suitable sample may be a magnetostrictive material or some other material having at least one side coated with a magnetostrictive material. When the sample is a suitable shape, i.e., a cube, rectangular parallelepiped, solid sphere or spherical shell, the elastic moduli or the material can be analytically determined from the measured resonance frequency spectrum. No mechanical transducers are required and the sample excitation is obtained without contact with the sample, leading to highly reproducible results and a measurement capability over a wide temperature range, e.g. from liquid nitrogen temperature to the Curie temperature of the magnetostrictive material.

  10. Apparatus for photon excited catalysis

    NASA Technical Reports Server (NTRS)

    Saffren, M. M. (inventor)

    1977-01-01

    An apparatus is described for increasing the yield of photonically excited gas phase reactions by extracting excess energy from unstable, excited species by contacting the species with the surface of a finely divided solid.

  11. Harmonically excited orbital variations

    SciTech Connect

    Morgan, T.

    1985-08-06

    Rephrasing the equations of motion for orbital maneuvers in terms of Lagrangian generalized coordinates instead of Newtonian rectangular cartesian coordinates can make certain harmonic terms in the orbital angular momentum vector more readily apparent. In this formulation the equations of motion adopt the form of a damped harmonic oscillator when torques are applied to the orbit in a variationally prescribed manner. The frequencies of the oscillator equation are in some ways unexpected but can nonetheless be exploited through resonant forcing functions to achieve large secular variations in the orbital elements. Two cases are discussed using a circular orbit as the control case: (1) large changes in orbital inclination achieved by harmonic excitation rather than one impulsive velocity change, and (2) periodic and secular changes to the longitude of the ascending node using both stable and unstable excitation strategies. The implications of these equations are also discussed for both artificial satellites and natural satellites. For the former, two utilitarian orbits are suggested, each exploiting a form of harmonic excitation. 5 refs.

  12. Brain Excitability in Stroke

    PubMed Central

    Carmichael, S. Thomas

    2015-01-01

    There is no current medical therapy for stroke recovery. Principles of physiological plasticity have been identified during recovery in both animal models and human stroke. Stroke produces a loss of physiological brain maps in adjacent peri-infarct cortex and then a remapping of motor and sensory functions in this region. This remapping of function in peri-infarct cortex correlates closely with recovery. Recent studies have shown that the stroke produces abnormal conditions of excitability in neuronal circuits adjacent to the infarct that may be the substrate for this process of brain remapping and recovery. Stroke causes a hypo-excitability in peri-infarct motor cortex that stems from increased tonic ?-aminobutyric acid activity onto neurons. Drugs that reverse this ?-aminobutyric acid signaling promote recovery after stroke. Stroke also increases the sensitivity of glutamate receptor signaling in peri-infarct cortex well after the stroke event, and stimulating ?-amino-3-hydroxyl-5-methyl-4-isoxazole-propionate glutamate receptors in peri-infarct cortex promotes recovery after stroke. Both blocking tonic ?-aminobutyric acid currents and stimulating ?-amino-3-hydroxyl-5-methyl-4-isoxazole-propionate receptors promote recovery after stroke when initiated at quite a delay, more than 3 to 5 days after the infarct. These changes in the excitability of neuronal circuits in peri-infarct cortex after stroke may underlie the process of remapping motor and sensory function after stroke and may identify new therapeutic targets to promote stroke recovery. PMID:21987395

  13. BROADBAND EXCITATION IN NUCLEAR MAGNETIC RESONANCE

    SciTech Connect

    Tycko, R.

    1984-10-01

    Theoretical methods for designing sequences of radio frequency (rf) radiation pulses for broadband excitation of spin systems in nuclear magnetic resonance (NMR) are described. The sequences excite spins uniformly over large ranges of resonant frequencies arising from static magnetic field inhomogeneity, chemical shift differences, or spin couplings, or over large ranges of rf field amplitudes. Specific sequences for creating a population inversion or transverse magnetization are derived and demonstrated experimentally in liquid and solid state NMR. One approach to broadband excitation is based on principles of coherent averaging theory. A general formalism for deriving pulse sequences is given, along with computational methods for specific cases. This approach leads to sequences that produce strictly constant transformations of a spin system. The importance of this feature in NMR applications is discussed. A second approach to broadband excitation makes use of iterative schemes, i.e. sets of operations that are applied repetitively to a given initial pulse sequences, generating a series of increasingly complex sequences with increasingly desirable properties. A general mathematical framework for analyzing iterative schemes is developed. An iterative scheme is treated as a function that acts on a space of operators corresponding to the transformations produced by all possible pulse sequences. The fixed points of the function and the stability of the fixed points are shown to determine the essential behavior of the scheme. Iterative schemes for broadband population inversion are treated in detail. Algebraic and numerical methods for performing the mathematical analysis are presented. Two additional topics are treated. The first is the construction of sequences for uniform excitation of double-quantum coherence and for uniform polarization transfer over a range of spin couplings. Double-quantum excitation sequences are demonstrated in a liquid crystal system. The second additional topic is the construction of iterative schemes for narrowband population inversion. The use of sequences that invert spin populations only over a narrow range of rf field amplitudes to spatially localize NMR signals in an rf field gradient is discussed.

  14. Excitation of Magnetic Dipole Transitions at Optical Frequencies

    NASA Astrophysics Data System (ADS)

    Kasperczyk, Mark; Person, Steven; Ananias, Duarte; Carlos, Luis D.; Novotny, Lukas

    2015-04-01

    We use the magnetic field distribution of an azimuthally polarized focused laser beam to excite a magnetic dipole transition in Eu3 + ions embedded in a Y2O3 nanoparticle. The absence of the electric field at the focus of an azimuthally polarized beam allows us to unambiguously demonstrate that the nanoparticle is excited by the magnetic dipole transition near 527.5 nm. When the laser wavelength is resonant with the magnetic dipole transition, the nanoparticle maps the local magnetic field distribution, whereas when the laser wavelength is resonant with an electric dipole transition, the nanoparticle is sensitive to the local electric field. Hence, by tuning the excitation wavelength, we can selectively excite magnetic or electric dipole transitions through optical fields.

  15. Excitation of magnetic dipole transitions at optical frequencies.

    PubMed

    Kasperczyk, Mark; Person, Steven; Ananias, Duarte; Carlos, Luis D; Novotny, Lukas

    2015-04-24

    We use the magnetic field distribution of an azimuthally polarized focused laser beam to excite a magnetic dipole transition in Eu^{3+} ions embedded in a Y2O3 nanoparticle. The absence of the electric field at the focus of an azimuthally polarized beam allows us to unambiguously demonstrate that the nanoparticle is excited by the magnetic dipole transition near 527.5 nm. When the laser wavelength is resonant with the magnetic dipole transition, the nanoparticle maps the local magnetic field distribution, whereas when the laser wavelength is resonant with an electric dipole transition, the nanoparticle is sensitive to the local electric field. Hence, by tuning the excitation wavelength, we can selectively excite magnetic or electric dipole transitions through optical fields. PMID:25955052

  16. NMR quantum simulation of localization effects induced by decoherence

    E-print Network

    Gonzalo A. Alvarez; Dieter Suter

    2010-04-28

    The loss of coherence in quantum mechanical superposition states limits the time for which quantum information remains useful. Similarly, it limits the distance over which quantum information can be transmitted, resembling Anderson localization, where disorder causes quantum mechanical states to become localized. Here, we investigate in a nuclear spin-based quantum simulator, the localization of the size of spin clusters that are generated by a Hamiltonian driving the transmission of information, while a variable-strength perturbation counteracts the spreading. We find that the system reaches a dynamic equilibrium size, which decreases with the square of the perturbation strength.

  17. Double Excitations of Helium

    NASA Astrophysics Data System (ADS)

    Menzel, Alexander

    1996-05-01

    The double excitations of helium offer an ideal case for investigating electron dynamics in a three-body system. Our study of the He ^1P^o double excitations comprises measurements of the partial photoionization cross sections ?n (He^+) and the partial photoelectron angular distribution parameters ?n for the series N(K,T)^Ai up to the N=5 threshold. The experiment was performed at the ALS undulator beam line 9.0.1., which provided a photon flux of 2 × 10^12 photons per second with a small photon energy bandpass of 7 to 12 meV. This level of differentiation, along with the small bandpass, offers the most critical assessment of the dynamics of the two-electron excitations to date. The principal series K=N-2 are clearly delineated in both ?n and ?_n. The ?n show all minor series with N=K-4 very clearly, in contrast to measurements of the total absorption cross section, as well as very weak members with A=-1. Excellent accord between experiment and theory, particularly the hyperspherical close-coupling method, was found for the dynamic properties in all instances, including the interference pattern due to an overlap of N=5 and N=6 series members. Generally, the Rydberg series of resonance-induced profiles vary greatly depending on the final ionic state He^+(n), whereas the peak-to-valley variation in the ?n within a given series N is of similar magnitude for all n. Interestingly, a striking systematic trend is noted through the various series: the resonance-induced profiles for both the ?n and ?n of the photoelectron satellites are virtually identical provided the final ionic state He^+(n), n >= 2, is reached via an excited series N with ?=1, or ?=2, where ?=N-n. This overall pattern might be attributed to the general similarity of states with the same set of approximately good quantum numbers (N-K), A, and T. We tentatively propose an extension of these systematics for higher series N >= 5, although further theoretical work toward understanding these features of the doubly excited states will be needed. The experiment was performed in close collaboration with C.D. Caldwell, M.O. Krause, S.P. Frigo, and S.B. Whitfield. Valuable theoretical contributions were made by J.-Z. Tang and I. Shimamura. Part of the work appeared in Phys. Rev. Lett. 75, 1479 (1995). This work is supported by the National Science Foundation under grants PHY-9207634 and PHY-9507573.

  18. Conformational Switching by Vibrational Excitation of a Remote NH Bond.

    PubMed

    Lopes Jesus, António Jorge; Reva, Igor; Araujo-Andrade, Cuauhtémoc; Fausto, Rui

    2015-11-18

    Here we describe an unprecedented reversible interconversion between two conformational states, accomplished by selective vibrational excitation of a bond remotely located in relation to the isomerizing fragment. In contrast to previous studies reporting conformational changes via vibrational excitation of a nearby OH group, in this study the transformations were successfully achieved by excitation of a distant NH stretching coordinate. The syn and anti forms of monomeric 6-methoxyindole, which differ in the orientation of the methoxy group, were trapped in low-temperature inert matrixes and characterized spectroscopically. These forms could be selectively shifted in both directions by using near-IR excitations tuned at the frequency of the first NH stretching overtone. The observed isomerization proves the possibility of efficient vibrational relaxation to carry the energy deposited at the NH stretching coordinate into the reactive C-O torsional mode localized on the methoxy group four bonds away from the excited NH moiety. PMID:26376202

  19. Dynamics of nonlinear excitations of helically confined charges

    E-print Network

    Zampetaki, A V; Schmelcher, P

    2015-01-01

    We explore the long-time dynamics of a system of identical charged particles trapped on a closed helix. This system has recently been found to exhibit an unconventional deformation of the linear spectrum when tuning the helix radius. Here we show that the same geometrical parameter can affect significantly also the dynamical behaviour of an initially broad excitation for long times. In particular, for small values of the radius, the excitation disperses into the whole crystal whereas within a specific narrow regime of larger radii the excitation self-focuses, assuming finally a localized form. Beyond this regime, the excitation defocuses and the dispersion gradually increases again. We analyze this geometrically controlled nonlinear behaviour using an effective discrete nonlinear Schr\\"{o}dinger model, which allows us among others to identify a number of breather-like excitations.

  20. Dynamics of nonlinear excitations of helically confined charges

    NASA Astrophysics Data System (ADS)

    Zampetaki, A. V.; Stockhofe, J.; Schmelcher, P.

    2015-10-01

    We explore the long-time dynamics of a system of identical charged particles trapped on a closed helix. This system has recently been found to exhibit an unconventional deformation of the linear spectrum when tuning the helix radius. Here we show that the same geometrical parameter can affect significantly also the dynamical behavior of an initially broad excitation for long times. In particular, for small values of the radius, the excitation disperses into the whole crystal whereas within a specific narrow regime of larger radii the excitation self-focuses, assuming finally a localized form. Beyond this regime, the excitation defocuses and the dispersion gradually increases again. We analyze this geometrically controlled nonlinear behavior using an effective discrete nonlinear Schrödinger model, which allows us among others to identify a number of breatherlike excitations.

  1. CellExcite: an efficient simulation environment for excitable cells

    PubMed Central

    Bartocci, Ezio; Corradini, Flavio; Entcheva, Emilia; Grosu, Radu; Smolka, Scott A

    2008-01-01

    Background Brain, heart and skeletal muscle share similar properties of excitable tissue, featuring both discrete behavior (all-or-nothing response to electrical activation) and continuous behavior (recovery to rest follows a temporal path, determined by multiple competing ion flows). Classical mathematical models of excitable cells involve complex systems of nonlinear differential equations. Such models not only impair formal analysis but also impose high computational demands on simulations, especially in large-scale 2-D and 3-D cell networks. In this paper, we show that by choosing Hybrid Automata as the modeling formalism, it is possible to construct a more abstract model of excitable cells that preserves the properties of interest while reducing the computational effort, thereby admitting the possibility of formal analysis and efficient simulation. Results We have developed CellExcite, a sophisticated simulation environment for excitable-cell networks. CellExcite allows the user to sketch a tissue of excitable cells, plan the stimuli to be applied during simulation, and customize the diffusion model. CellExcite adopts Hybrid Automata (HA) as the computational model in order to efficiently capture both discrete and continuous excitable-cell behavior. Conclusions The CellExcite simulation framework for multicellular HA arrays exhibits significantly improved computational efficiency in large-scale simulations, thus opening the possibility for formal analysis based on HA theory. A demo of CellExcite is available at . PMID:18387205

  2. Get excited: reappraising pre-performance anxiety as excitement.

    PubMed

    Brooks, Alison Wood

    2014-06-01

    Individuals often feel anxious in anticipation of tasks such as speaking in public or meeting with a boss. I find that an overwhelming majority of people believe trying to calm down is the best way to cope with pre-performance anxiety. However, across several studies involving karaoke singing, public speaking, and math performance, I investigate an alternative strategy: reappraising anxiety as excitement. Compared with those who attempt to calm down, individuals who reappraise their anxious arousal as excitement feel more excited and perform better. Individuals can reappraise anxiety as excitement using minimal strategies such as self-talk (e.g., saying "I am excited" out loud) or simple messages (e.g., "get excited"), which lead them to feel more excited, adopt an opportunity mind-set (as opposed to a threat mind-set), and improve their subsequent performance. These findings suggest the importance of arousal congruency during the emotional reappraisal process. PMID:24364682

  3. Broadband near-field enhancement in the macro-periodic and micro-random structure with a hybridized excitation of propagating Bloch-plasmonic and localized surface-plasmonic modes

    NASA Astrophysics Data System (ADS)

    Lu, Haifei; Ren, Xingang; Sha, Wei E. I.; Ho, Ho-Pui; Choy, Wallace C. H.

    2015-10-01

    We demonstrate that the silver nanoplate-based macroscopically periodic (macro-periodic) and microscopically random (micro-random) structure has a broadband near-field enhancement as compared to conventional silver gratings. The specific field enhancement in a wide spectral range (from UV to near-infrared) originates from the abundance of localized surface-plasmonic (LSP) modes in the microscopically random distributed silver nanoplates and propagating Bloch-plasmonic (PBP) modes from the macroscopically periodic pattern. The characterization of polarization dependent spectral absorption, surface-enhanced Raman spectroscopy (SERS), as well as theoretical simulation was conducted to comprehensively understand the features of the broadband spectrum and highly concentrated near-field. The reported macro-periodic and micro-random structure may offer a new route for the design of plasmonic systems for photonic and optoelectronic applications.We demonstrate that the silver nanoplate-based macroscopically periodic (macro-periodic) and microscopically random (micro-random) structure has a broadband near-field enhancement as compared to conventional silver gratings. The specific field enhancement in a wide spectral range (from UV to near-infrared) originates from the abundance of localized surface-plasmonic (LSP) modes in the microscopically random distributed silver nanoplates and propagating Bloch-plasmonic (PBP) modes from the macroscopically periodic pattern. The characterization of polarization dependent spectral absorption, surface-enhanced Raman spectroscopy (SERS), as well as theoretical simulation was conducted to comprehensively understand the features of the broadband spectrum and highly concentrated near-field. The reported macro-periodic and micro-random structure may offer a new route for the design of plasmonic systems for photonic and optoelectronic applications. Electronic supplementary information (ESI) available. See DOI: 10.1039/c5nr03391h

  4. Excitation of Resonant Helioseimic Modes by Solar Flares.

    NASA Astrophysics Data System (ADS)

    Leibacher, John W.; Baudin, Frédéric; Rabello Soares,, Maria Cristina

    2015-08-01

    Flares are known to excite propagating sound waves in the solar atmosphere, and Maurya et al. (2009), using a local analysis (ring diagrams) of the 2003 Halloween flare, showed that they excite resonant p-modes as well. We confirm and extend here these results by:-applying the same analysis to other locations on the Sun at the time of the Halloween flare-analyzing other events also showing a signature of p-mode excitation-looking in detail at the results of the ring diagrams analysis in terms of noise fitting and the center-to-limb variation of ring-diagram power.

  5. Small ab initio Cu(II) oxide cluster model with localized states and strong screening effects accompanying ionization

    NASA Astrophysics Data System (ADS)

    Kondratenko, A. V.; Cederbaum, L. S.

    1991-05-01

    A neutral Cu(II) oxide CuO cluster with external point charges is studied in some detail. This cluster is small enough to allow the investigation of many-body effects by ab initio approaches. The electronic structure of the ground and low excited states as well as of core and valence ionic states of the cluster is discussed. We have thereby applied self-consistent-field, configuration-interaction, and Green's-function methods. The possibility is discussed that the cluster may serve as a model for solid-state Cu(II) oxides. The calculations show that the one-electron states of the cluster are strongly localized on either the copper or oxygen site. Strong screening effects are found to accompany the ionization of both valence and core metal levels of the cluster and result in many-electron shakedown satellites in the spectra. These effects are connected with an intense charge-transfer process from the occupied O 2p states to the vacant Cu 3d? states in accord with predictions of non-parameter-free approaches (based on the Anderson impurity model, the Hubbard model, and other models) for the respective solid-state Cu(II) oxides. Connection is made with experimental x-ray-photoelectron and optical spectra. To substantiate the findings, the results of Green's-function calculations on ZnO and CuO- clusters are also discussed, which are of interest by themselves.

  6. Excitability in Dictyostelium development

    NASA Astrophysics Data System (ADS)

    Schwab, David

    2013-03-01

    Discovering how populations of cells reliably develop into complex multi-cellular structures is a key challenge in modern developmental biology. This requires an understanding of how networks at the single-cell level, when combined with intercellular signaling and environmental cues, give rise to the collective behaviors observed in cellular populations. I will present work in collaboration with the Gregor lab, showing that the signal-relay response of starved cells of the amoebae Dictyostelium discoideum can be well modeled as an excitable system. This is in contrast to existing models of the network that postulate a feed-forward cascade. I then extend the signal-relay model to describe how spatial gradient sensing may be achieved via excitability. One potential advantage of relying on feedback for gradient sensing is in preventing ``cheaters'' that do not produce signals from taking over the population. I then combine these models of single-cell signaling and chemotaxis to perform large-scale agent-based simulations of aggregating populations. This allows direct study of how variations in single-cell dynamics modify population behavior. In order to further test this model, I use the results of a screen for mutant cell lines that exhibit altered collective patterns. Finally, I use an existing FRET movie database of starved cell populations at varying cell densities and dilution rates to study heterogeneity in repeated spatio-temporal activity patterns.

  7. Physical, chemical, and isotopic data for samples from the Anderson Springs area, Lake County, California, 1998-1999

    USGS Publications Warehouse

    Janik, C.J.; Goff, F.; Sorey, M.L.; Rytuba, J.J.; Counce, D.; Colvard, E.M.; Huebner, M.; White, L.D.; Foster, A.

    1999-01-01

    Anderson Springs is located about 90 miles (145 kilometers) north of San Francisco, California, in the southwestern part of Lake County. The area was first developed in the late 1800s as a health resort, which was active until the 1930s. In the rugged hills to the south of the resort were four small mercury mines of the eastern Mayacmas quicksilver district. About 1,260 flasks of mercury were produced from these mines between 1909 and 1943. In the 1970s, the high-elevation areas surrounding Anderson Springs became part of The Geysers geothermal field. Today, several electric powerplants are located on the ridges above Anderson Springs, utilizing steam produced from a 240°C vapor-dominated reservoir. The primary purpose of this report is to provide physical, chemical, and isotopic data on samples collected in the Anderson Springs area during 1998 and 1999, in response to a Freedom of Information Act request. In July 1998, drainage from the Schwartz adit of the abandoned Anderson mercury mine increased substantially over a 2-day period, transporting a slurry of water and precipitates down a tributary and into Anderson Creek. In August 1998, J.J. Rytuba and coworkers sampled the Schwartz adit drainage and water from the Anderson Springs Hot Spring for base metal and methylmercury analysis. They measured a maximum temperature (Tm) of 85°C in the Hot Spring. Published records show that the temperature of the Anderson Springs Hot Spring (main spring) was 63°C in 1889, 42–52°C from 1974 through 1991, and 77°C in March 1995. To investigate possible changes in thermal spring activity and to collect additional samples for geochemical analysis, C.J. Janik and coworkers returned to the area in September and December 1998. They determined that a cluster of springs adjacent to the main spring had Tm=98°C, and they observed that a new area of boiling vents and small fumaroles (Tm=99.3°C) had formed in an adjacent gully about 20 meters to the north of the main spring. During August–October 1999, several field trips were conducted in the vicinity of Anderson Springs to continue monitoring and sampling the thermal manifestations. The new fumarolic area had increased in temperature and in discharge intensity since 1998, and a zone of dead trees had developed on the steep bank directly west of the fumaroles. Ground temperatures and diffuse flow of CO2 flow through soils were measured in the area surrounding the main spring and new fumaroles and in the zone of tree-kill.

  8. Vibrations of acrylonitrile in N 1s excited states

    NASA Astrophysics Data System (ADS)

    Ilakovac, V.; Carniato, S.; Gallet, J.-J.; Kukk, E.; Horvati?, D.; Ilakovac, A.

    2008-01-01

    The N 1s near edge x-ray absorption fine structure spectra of acrylonitrile gas are accurately reproduced by a complete ab initio multidimensional vibrational analysis. The role of ?? -orbital localization and hybridization on vibrations accompanying core excitation is discussed. Transition to the ???(C=C-C?N) delocalized orbital excites mostly stretching vibrations of the whole spinal column of the molecule. Promoting a core electron to the localized ???(C?N) produces C?N stretching vibration combined with two strong bending modes of the C-C?N end of the molecule, related to the change of carbon hybridization.

  9. Electronic excitation as a mode of heat dissipation in laser-driven cluster plasmas

    SciTech Connect

    Rajeev, R.; Rishad, K. P. M.; Madhu Trivikram, T.; Krishnamurthy, M.

    2013-12-15

    Electrons streaming out of laser plasma are known for non-local heat transport and energy deposition by the ionization wave. At 100 eV electron temperature, since the electronic excitation cross section is comparable to that of ionization for Ar and CO{sub 2}, a non-local excitation wave akin to the ionization wave is envisaged where energy deposition in excitations forms a excited cluster sheath beyond the laser focus. Here, we show that nano-cluster systems have the right parameters to form such an exciton sheath and experimentally demonstrate this via charge transfer reactions.

  10. Fractal superconductivity near localization threshold

    SciTech Connect

    Feigel'man, M.V.; Ioffe, L.B.; Kravtsov, V.E.; Cuevas, E.

    2010-07-15

    We develop a semi-quantitative theory of electron pairing and resulting superconductivity in bulk 'poor conductors' in which Fermi energy E{sub F} is located in the region of localized states not so far from the Anderson mobility edge E{sub c}. We assume attractive interaction between electrons near the Fermi surface. We review the existing theories and experimental data and argue that a large class of disordered films is described by this model. Our theoretical analysis is based on analytical treatment of pairing correlations, described in the basis of the exact single-particle eigenstates of the 3D Anderson model, which we combine with numerical data on eigenfunction correlations. Fractal nature of critical wavefunction's correlations is shown to be crucial for the physics of these systems. We identify three distinct phases: 'critical' superconductive state formed at E{sub F} = E{sub c}, superconducting state with a strong pseudo-gap, realized due to pairing of weakly localized electrons and insulating state realized at E{sub F} still deeper inside a localized band. The 'critical' superconducting phase is characterized by the enhancement of the transition temperature with respect to BCS result, by the inhomogeneous spatial distribution of superconductive order parameter and local density of states. The major new feature of the pseudo-gapped state is the presence of two independent energy scales: superconducting gap {Delta}, that is due to many-body correlations and a new 'pseudo-gap' energy scale {Delta}{sub P} which characterizes typical binding energy of localized electron pairs and leads to the insulating behavior of the resistivity as a function of temperature above superconductive T{sub c}. Two gap nature of the pseudo-gapped superconductor is shown to lead to specific features seen in scanning tunneling spectroscopy and point-contact Andreev spectroscopy. We predict that pseudo-gapped superconducting state demonstrates anomalous behavior of the optical spectral weight. The insulating state is realized due to the presence of local pairing gap but without superconducting correlations; it is characterized by a hard insulating gap in the density of single electrons and by purely activated low-temperature resistivity ln R(T) {approx} 1/T. Based on these results we propose a new 'pseudo-spin' scenario of superconductor-insulator transition and argue that it is realized in a particular class of disordered superconducting films. We conclude by the discussion of the experimental predictions of the theory and the theoretical issues that remain unsolved.

  11. Molecular analysis and intestinal expression of SAR1 genes and proteins in Anderson's disease (Chylomicron retention disease)

    PubMed Central

    2011-01-01

    Background Anderson's disease (AD) or chylomicron retention disease (CMRD) is a very rare hereditary lipid malabsorption syndrome. In order to discover novel mutations in the SAR1B gene and to evaluate the expression, as compared to healthy subjects, of the Sar1 gene and protein paralogues in the intestine, we investigated three previously undescribed individuals with the disease. Methods The SAR1B, SAR1A and PCSK9 genes were sequenced. The expression of the SAR1B and SAR1A genes in intestinal biopsies of both normal individuals and patients was measured by RTqPCR. Immunohistochemistry using antibodies to recombinant Sar1 protein was used to evaluate the expression and localization of the Sar1 paralogues in the duodenal biopsies. Results Two patients had a novel SAR1B mutation (p.Asp48ThrfsX17). The third patient, who had a previously described SAR1B mutation (p.Leu28ArgfsX7), also had a p.Leu21dup variant of the PCSK9 gene. The expression of the SAR1B gene in duodenal biopsies from an AD/CMRD patient was significantly decreased whereas the expression of the SAR1A gene was significantly increased, as compared to healthy individuals. The Sar1 proteins were present in decreased amounts in enterocytes in duodenal biopsies from the patients as compared to those from healthy subjects. Conclusions Although the proteins encoded by the SAR1A and SAR1B genes are 90% identical, the increased expression of the SAR1A gene in AD/CMRD does not appear to compensate for the lack of the SAR1B protein. The PCSK9 variant, although reported to be associated with low levels of cholesterol, does not appear to exert any additional effect in this patient. The results provide further insight into the tissue-specific nature of AD/CMRD. PMID:21235735

  12. Dynamical Localization for Discrete and Continuous Random Schrödinger Operators

    NASA Astrophysics Data System (ADS)

    Germinet, F.; De Bièvre, S.

    We show for a large class of random Schrödinger operators Ho on and on that dynamical localization holds, i.e. that, with probability one, for a suitable energy interval I and for q a positive real, Here ? is a function of sufficiently rapid decrease, and PI(Ho) is the spectral projector of Ho corresponding to the interval I. The result is obtained through the control of the decay of the eigenfunctions of Ho and covers, in the discrete case, the Anderson tight-binding model with Bernoulli potential (dimension ? = 1) or singular potential (? > 1), and in the continuous case Anderson as well as random Landau Hamiltonians.

  13. Causation's nuclear future: applying proportional liability to the Price-Anderson Act.

    PubMed

    O'Connell, William D

    2014-11-01

    For more than a quarter century, public discourse has pushed the nuclear-power industry in the direction of heavier regulation and greater scrutiny, effectively halting construction of new reactors. By focusing on contemporary fear of significant accidents, such discourse begs the question of what the nation's court system would actually do should a major nuclear incident cause radiation-induced cancers. Congress's attempt to answer that question is the Price-Anderson Act, a broad statute addressing claims by the victims of a major nuclear accident. Lower courts interpreting the Act have repeatedly encountered a major stumbling block: it declares that judges must apply the antediluvian preponderance-of-the-evidence logic of state tort law, even though radiation science insists that the causes of radiation-induced cancers are more complex. After a major nuclear accident, the Act's paradoxically outdated rules for adjudicating "causation" would make post-incident compensation unworkable. This Note urges that nuclear-power-plant liability should not turn on eighteenth-century tort law. Drawing on modern scientific conclusions regarding the invariably "statistical" nature of cancer, this Note suggests a unitary federal standard for the Price-Anderson Act--that a defendant be deemed to have "caused" a plaintiff's injury in direct proportion to the increased risk of harm the defendant has imposed. This "proportional liability" rule would not only fairly evaluate the costs borne by injured plaintiffs and protect a reawakening nuclear industry from the prospect of bank-breaking litigation, but would prove workable with only minor changes to the Price-Anderson Act's standards of "injury" and "fault." PMID:25507406

  14. Causation's nuclear future: applying proportional liability to the Price-Anderson Act.

    PubMed

    O'Connell, William D

    2014-11-01

    For more than a quarter century, public discourse has pushed the nuclear-power industry in the direction of heavier regulation and greater scrutiny, effectively halting construction of new reactors. By focusing on contemporary fear of significant accidents, such discourse begs the question of what the nation's court system would actually do should a major nuclear incident cause radiation-induced cancers. Congress's attempt to answer that question is the Price-Anderson Act, a broad statute addressing claims by the victims of a major nuclear accident. Lower courts interpreting the Act have repeatedly encountered a major stumbling block: it declares that judges must apply the antediluvian preponderance-of-the-evidence logic of state tort law, even though radiation science insists that the causes of radiation-induced cancers are more complex. After a major nuclear accident, the Act's paradoxically outdated rules for adjudicating "causation" would make post-incident compensation unworkable. This Note urges that nuclear-power-plant liability should not turn on eighteenth-century tort law. Drawing on modern scientific conclusions regarding the invariably "statistical" nature of cancer, this Note suggests a unitary federal standard for the Price-Anderson Act--that a defendant be deemed to have "caused" a plaintiff's injury in direct proportion to the increased risk of harm the defendant has imposed. This "proportional liability" rule would not only fairly evaluate the costs borne by injured plaintiffs and protect a reawakening nuclear industry from the prospect of bank-breaking litigation, but would prove workable with only minor changes to the Price-Anderson Act's standards of "injury" and "fault." PMID:25423683

  15. Neural Excitability and Singular Bifurcations.

    PubMed

    De Maesschalck, Peter; Wechselberger, Martin

    2015-12-01

    We discuss the notion of excitability in 2D slow/fast neural models from a geometric singular perturbation theory point of view. We focus on the inherent singular nature of slow/fast neural models and define excitability via singular bifurcations. In particular, we show that type I excitability is associated with a novel singular Bogdanov-Takens/SNIC bifurcation while type II excitability is associated with a singular Andronov-Hopf bifurcation. In both cases, canards play an important role in the understanding of the unfolding of these singular bifurcation structures. We also explain the transition between the two excitability types and highlight all bifurcations involved, thus providing a complete analysis of excitability based on geometric singular perturbation theory. PMID:26246435

  16. Fusion excitation function revisited

    E-print Network

    Ph. Eudes; Z. Basrak; F. Sébille; V. de la Mota; G. Royer; M. Zori?

    2012-09-28

    We report on a comprehensive systematics of fusion-evaporation and/or fusion-fission cross sections for a very large variety of systems over an energy range 4-155 A.MeV. Scaled by the reaction cross sections, fusion cross sections do not show a universal behavior valid for all systems although a high degree of correlation is present when data are ordered by the system mass asymmetry.For the rather light and close to mass-symmetric systems the main characteristics of the complete and incomplete fusion excitation functions can be precisely determined. Despite an evident lack of data above 15A.MeV for all heavy systems the available data suggests that geometrical effects could explain the persistence of incomplete fusion at incident energies as high as 155A.MeV.

  17. Data Center Energy Efficiency and Renewable Energy Site Assessment: Anderson Readiness Center; Salem, Oregon

    SciTech Connect

    Metzger, I.; Van Geet, O.

    2014-06-01

    This report summarizes the results from the data center energy efficiency and renewable energy site assessment conducted for the Oregon Army National Guard in Salem, Oregon. A team led by NREL conducted the assessment of the Anderson Readiness Center data centers March 18-20, 2014 as part of ongoing efforts to reduce energy use and incorporate renewable energy technologies where feasible. Although the data centers in this facility account for less than 5% of the total square footage, they are estimated to be responsible for 70% of the annual electricity consumption.

  18. Quantum transport and integrability of the Anderson model for a quantum dot with multiple leads

    NASA Astrophysics Data System (ADS)

    Cho, Sam Young; Zhou, Huan-Qiang; McKenzie, Ross H.

    2003-09-01

    We show that an Anderson Hamiltonian describing a quantum dot connected to multiple leads is integrable. A general expression for the nonlinear conductance is obtained by combining the Bethe ansatz exact solution with Landauer-Büttiker theory. In the Kondo regime, a closed form expression is given for the matrix conductance at zero temperature and when all the leads are close to the symmetric point. A bias-induced splitting of the Kondo resonance is possible for three or more leads. Specifically, for N leads, with each at a different chemical potential, there can be N-1 Kondo peaks in the conductance.

  19. STS-118 Astronaut Williams and Expedition 15 Engineer Anderson Perform EVA

    NASA Technical Reports Server (NTRS)

    2007-01-01

    As the construction continued on the International Space Station (ISS), STS-118 Astronaut Dave Williams, representing the Canadian Space Agency, participated in the fourth and final session of Extra Vehicular Activity (EVA). During the 5 hour space walk, Williams and Expedition 15 engineer Clay Anderson (out of frame) installed the External Wireless Instrumentation System Antenna, attached a stand for the shuttle robotic arm extension boom, and retrieved the two Materials International Space Station Experiments (MISSE) for return to Earth. MISSE collects information on how different materials weather in the environment of space.

  20. STS-107 Payload Commander Michael Anderson during TCDT M113 training activities

    NASA Technical Reports Server (NTRS)

    2002-01-01

    KENNEDY SPACE CENTER, FLA. -- -- STS-107 Payload Commander Michael Anderson takes a break during training on the operation of an M113 armored personnel carrier during Terminal Countdown Demonstration Test activities, a standard part of launch preparations. STS-107 is a mission devoted to research and will include more than 80 experiments that will study Earth and space science, advanced technology development, and astronaut health and safety. Launch is planned for Jan. 16, 2003, between 10 a.m. and 2 p.m. EST aboard Space Shuttle Columbia.

  1. Observation of the Anderson Metal-Insulator Transition with Atomic Matter Waves: Theory and Experiment

    E-print Network

    Gabriel Lemarié; Julien Chabé; Pascal Szriftgiser; Jean-Claude Garreau; Benoît Grémaud; Dominique Delande

    2009-07-20

    Using a cold atomic gas exposed to laser pulses -- a realization of the chaotic quasiperiodic kicked rotor with three incommensurate frequencies -- we study experimentally and theoretically the Anderson metal-insulator transition in three dimensions. Sensitive measurements of the atomic wavefunction and the use of finite-size scaling techniques make it possible to unambiguously demonstrate the existence of a quantum phase transition and to measure its critical exponents. By taking proper account of systematic corrections to one-parameter scaling, we show the universality of the critical exponent $\

  2. Elementary excitations and flow in the liquid

    NASA Astrophysics Data System (ADS)

    Egami, Takeshi

    2013-03-01

    A new mode of excitation is introduced to elucidate the dynamics in simple liquids at the atomic scale. Some properties of liquid defy easy explanations. For instance, in liquids phonons are overdamped with a very short lifetime. Nevertheless the Dulong-Petit law (CV ~ 3kB) is widely observed at high temperatures. As temperature is reduced the specific heat markedly increases in the supercooled state, only to drop down sharply at the glass transition. Viscosity shows an Arrhenian behavior at high temperatures, but increases rapidly toward the glass transition in the supercooled state. We suggest that these perplexing observations can be naturally explained in terms of the local configurational excitations (LCE's) which locally change the atomic connectivity by an atom losing or gaining one nearest neighbor. We show that the lifetime of LCE, ?LC, is equal to the Maxwell relaxation time, ?M, at temperatures above the crossover temperature, TA. Above TA the phonon mean-free path, ? =cT?LC , where cT is the transverse sound velocity, becomes shorter than the interatomic distance, resulting in phonon localization. Therefore LCE's are the elementary excitations in the liquid. They are independent of each other above TA, but below TA LCE's interact through phonon exchange, resulting in the rapid increase in ?M , culminatingintheglasstransition . LCE' sarealsothemechanism of flow at low temperature under strong shear stress. In this case, however, losing and gaining of the neighbors are strongly coupled, so that ?M = LC / 2 [ 1 ] . Wealsodiscussdynamicheterogeneityin terms of LCE interactions. This work was supported by the U.S. Department of Energy, Office of Basic Energy Sciences, Materials Science and Engineering Division.

  3. Optically excited states in positronium

    NASA Technical Reports Server (NTRS)

    Howell, R. H.; Ziock, Klaus P.; Magnotta, F.; Dermer, Charles D.; Failor, R. A.; Jones, K. M.

    1990-01-01

    Optical excitation are reported of the 1 3S-2 3P transition in positronium, and a second excitation from n=2 to higher n states. The experiment used light from two pulsed dye lasers. Changes in the positronium annihilation rate during and after the laser pulse were used to deduce the excited state populations. The n=2 level was found to be saturable and excitable to a substantial fraction of n=2 positronium to higher levels. Preliminary spectroscopic measurements were performed on n=14 and n=15 positronium.

  4. Pattern Formation in Excitable Media

    NASA Astrophysics Data System (ADS)

    Reynolds, William Nash

    1992-01-01

    The phenomenon of excitability is observed in a wide variety of physical and biological systems. In this work, spatially extended excitable systems are examined from several different perspectives. First, a pedagogical introduction is used to motivate the derivation of the dynamics of one dimensional excitable pulses. In the second part, coupled map techniques for numerical simulation of excitable media and other interfacial systems are described. Examples are given for both excitable media and crystal growth. The third chapter addresses the phenomenon of spiral formation in excitable media. Exact rotating solutions are found for a class of models of excitable media. The solutions consist of two regions: an outer region, consisting of the spiral proper, which exhibits a singularity at its tip, and the core region, obtained by rescaling space in the vicinity of the tip. The tip singularity is resolved in the core region, leading to a consistent solution in all of space. The stability of both the spiral and the core is investigated, with the result that the spiral is found to be stable, and the core unstable. Finally, the stability of excitable waves of the chemical cAMP traveling over aggregating colonies of the slime mold Dictyostelium discoideum is examined by coupling the excitable dynamics of the cAMP signalling system to a simple model of chemotaxis, with result that cellular motion is found to destabilize the waves, causing the initially uniform field of cells to break up into streams.

  5. ANDERSON-TEIXEIRA FINAL PROOF.DOCX (DO NOT DELETE) 3/7/2011 9:29 AM DO BIOFUELS LIFE CYCLE

    E-print Network

    DeLucia, Evan H.

    ANDERSON-TEIXEIRA FINAL PROOF.DOCX (DO NOT DELETE) 3/7/2011 9:29 AM 589 DO BIOFUELS LIFE CYCLE ANALYSES ACCURATELY QUANTIFY THE CLIMATE IMPACTS OF BIOFUELS-RELATED LAND USE CHANGE? Kristina J. Anderson in determining the sustainability of biofuels. To ensure that legal standards are effective in limiting climate

  6. A review of "Translating Investments: Metaphor and the Dynamic of Cultural Change in Tudor-Stuart England." by Judith H. Anderson 

    E-print Network

    Ira Clark

    2006-01-01

    of two poles of translation that include extended, transferred, or polysemous use vs misuse or excessive use, and use requisite for lack of a word, extended or tropic use vs misuse or degenerative or improper use. Anderson?s motto counterbalancing one...

  7. The Long Tail: Why the Future of Business is Selling Less or More, Chris Anderson. Hyperion, New York (2006). $24.95, ISBN: 1-4013-0237-8

    E-print Network

    Jansen, James

    2006-01-01

    The Long Tail: Why the Future of Business is Selling Less or More, Chris Anderson. Hyperion, New York (2006). $24.95, ISBN: 1-4013-0237-8 The Long Tail: How Technology is turning mass markets by Chris Anderson is a good and worthwhile read for information scientists, computer scientists, ecommerce

  8. Localization and Glassiness of Bosonic Mixtures in Optical Lattices

    NASA Astrophysics Data System (ADS)

    Roscilde, T.; Horstmann, B.; Cirac, J. I.

    2008-06-01

    In this paper we deal with the general subject of realizing disordered states in optical lattices by using an unequal mixture of fast and slow (or frozen) particles. We discuss the onset of Anderson localization of fast hardcore bosons when brought into interaction with the random potential created by secondary hardcore bosons frozen in a superfluid state. In the case of softcore bosons we discuss how localization phenomena, in the form of fragmentation of the mixture into many metastable droplets, intervene when trying to reach the equilibrium ground state of the system.

  9. Probing many-body localization by spin noise spectroscopy

    NASA Astrophysics Data System (ADS)

    Roy, Dibyendu; Singh, Rajeev; Moessner, Roderich

    2015-11-01

    We propose to apply spin noise spectroscopy (SNS) to detect many-body localization (MBL) in disordered spin systems. The SNS methods are relatively noninvasive techniques to probe spontaneous spin fluctuations. Here, we show that the spin noise signals obtained by cross-correlation SNS with two probe beams can be used to separate the MBL phase from a noninteracting Anderson localized phase and a delocalized (diffusive) phase in the studied models for which we numerically calculate real-time spin noise signals and their power spectra. For an archetypical case of the disordered XXZ spin chain, we also develop a simple phenomenological model.

  10. VOLUME 86, NUMBER 13 P H Y S I C A L R E V I E W L E T T E R S 26 MARCH 2001 Exponential Gain in Quantum Computing of Quantum Chaos and Localization

    E-print Network

    Shepelyansky, Dima

    in Quantum Computing of Quantum Chaos and Localization B. Georgeot and D. L. Shepelyansky Laboratoire de, local- ization, and Anderson transition can be modeled efficiently on a quantum computer. We also show reviews [1,2]). That opens new horizons for computations based on quantum mechanics, as was stressed

  11. Two-photon excited UV fluorescence for protein crystal detection

    PubMed Central

    Madden, Jeremy T.; DeWalt, Emma L.; Simpson, Garth J.

    2011-01-01

    Two-photon excited ultraviolet fluorescence (TPE-UVF) microscopy is explored for sensitive protein-crystal detection as a complement to second-order nonlinear optical imaging of chiral crystals (SONICC). Like conventional ultraviolet fluorescence (UVF), TPE-UVF generates image contrast based on the intrinsic fluorescence of aromatic residues, generally producing higher fluorescence emission within crystals than the mother liquor by nature of the higher local protein concentration. However, TPE-UVF has several advantages over conventional UVF, including (i) insensitivity to optical scattering, allowing imaging in turbid matrices, (ii) direct compatibility with conventional optical plates and windows by using visible light for excitation, (iii) elimination of potentially damaging out-of-plane UV excitation, (iv) improved signal to noise through background reduction from out-of-plane excitation and (v) relatively simple integration into instrumentation developed for SONICC. PMID:21931215

  12. Electronic structure and correlations of vitamin B12 studied within the Haldane-Anderson impurity model

    E-print Network

    Kandemir, Zafer; Bulut, Nejat

    2015-01-01

    We study the electronic structure and correlations of vitamin B12 (cyanocobalamine) by using the framework of the multi-orbital single-impurity Haldane-Anderson model of a transition-metal impurity in a semiconductor host. In this approach, the cobalt 3d orbitals are treated as the impurity states placed in a semiconductor host where the host consists of the rest of the molecule. The parameters of the resulting effective Haldane-Anderson model are obtained within the Hartree-Fock (HF) approximation. The quantum Monte Carlo (QMC) technique is then used to calculate the one-electron and magnetic correlation functions of this effective model. We observe that new states form inside the semiconductor gap found by HF due to the intra-orbital Coulomb interaction at the impurity 3d orbitals. In particular, the lowest unoccupied states correspond to an impurity bound state, which consists of the states from the CN axial ligand and the corring ring as well as the Co e_g orbitals. We present results on the charge distri...

  13. Volcanic termor: Nonlinear excitation by fluid flow

    NASA Astrophysics Data System (ADS)

    Julian, Bruce R.

    1994-06-01

    A nonlinear process analogous to the excitation mechanism of musical wind instruments and human vocal cords can explain many characteristics of volcanic tremor, including (1) periodic and 'chaotic' oscillations, with peaked and irregular spectra respectively, (2) rapid pulsations in eruptions occurring at the same frequency as tremor, (3) systematic changes in tremor amplitude as channel geometry evolves during an eruption, (4) the period doubling reported for Hawaiian deep tremor, and (5) the fact that the onset of termor can be either gradual or abrupt. Volcanic 'long-period' earthquakes can be explained as oscillations excited by transient disturbances produced by nearby earthquakes, fluid heterogeneity, or changes in channel geometry, when the magma flow rate is too low to excite continuous tremor. A simple lumped-parameter tremor model involving the flow of an incompressible viscous fluid through a channel with movable elastic walls leads to a third-order system of nonlinear ordinary differential equations. For different driving fluid pressures, numerical solutions exhibit steady flow, simple limit-cycle oscillations, a cascade of period-doubling subharmonic bifurcations, and chaotic oscillations controlled by a strange attractor of Rossler type. In this model, tremor occurs most easily at local constrictions, and fluid discharge is lower than would occur in unstable steady flow.

  14. Suppression of Rydberg excitation in an ultracold atomic sample

    NASA Astrophysics Data System (ADS)

    Tong, D.; Farooqi, S. M.; Stanojevic, J.; Krishnan, S.; Zhang, Y. P.; Côté, R.; Eyler, E. E.; Gould, P. L.

    2004-05-01

    Recently, the dipole blockade mechanism(M.D. Lukin et al.), Phys. Rev. Lett. 87, 037901 (2001). has been proposed to implement quantum information processing using Rydberg atoms. We report an advance toward this goal, a local excitation blockade in an ultracold sample containing 10^7 ^85Rb atoms. We illuminate the sample with narrowband ( ˜ 100 MHz) 297 nm UV pulses to excite atoms to np_3/2 states (n=30, 70, and 80). The resulting Rydberg atoms are detected by pulsed field ionization. We observe a dramatic suppression of excitation for n=70 and 80, whereas n=30 behaves as isolated atoms. Our local blockade arises, not from dipolie interactions, but from van der Waals interactions which scale very rapidly with n. We present results on the dependence of the blockade on both laser irradiance and atom density, and compare with a mean-field model. The model and experimental measurements agree well.

  15. Excited waves in shear layers

    NASA Technical Reports Server (NTRS)

    Bechert, D. W.

    1982-01-01

    The generation of instability waves in free shear layers is investigated. The model assumes an infinitesimally thin shear layer shed from a semi-infinite plate which is exposed to sound excitation. The acoustical shear layer excitation by a source further away from the plate edge in the downstream direction is very weak while upstream from the plate edge the excitation is relatively efficient. A special solution is given for the source at the plate edge. The theory is then extended to two streams on both sides of the shear layer having different velocities and densities. Furthermore, the excitation of a shear layer in a channel is calculated. A reference quantity is found for the magnitude of the excited instability waves. For a comparison with measurements, numerical computations of the velocity field outside the shear layer were carried out.

  16. Vibrational excitation induces double reaction.

    PubMed

    Huang, Kai; Leung, Lydie; Lim, Tingbin; Ning, Zhanyu; Polanyi, John C

    2014-12-23

    Electron-induced reaction at metal surfaces is currently the subject of extensive study. Here, we broaden the range of experimentation to a comparison of vibrational excitation with electronic excitation, for reaction of the same molecule at the same clean metal surface. In a previous study of electron-induced reaction by scanning tunneling microscopy (STM), we examined the dynamics of the concurrent breaking of the two C-I bonds of ortho-diiodobenzene physisorbed on Cu(110). The energy of the incident electron was near the electronic excitation threshold of E0=1.0 eV required to induce this single-electron process. STM has been employed in the present work to study the reaction dynamics at the substantially lower incident electron energies of 0.3 eV, well below the electronic excitation threshold. The observed increase in reaction rate with current was found to be fourth-order, indicative of multistep reagent vibrational excitation, in contrast to the first-order rate dependence found earlier for electronic excitation. The change in mode of excitation was accompanied by altered reaction dynamics, evidenced by a different pattern of binding of the chemisorbed products to the copper surface. We have modeled these altered reaction dynamics by exciting normal modes of vibration that distort the C-I bonds of the physisorbed reagent. Using the same ab initio ground potential-energy surface as in the prior work on electronic excitation, but with only vibrational excitation of the physisorbed reagent in the asymmetric stretch mode of C-I bonds, we obtained the observed alteration in reaction dynamics. PMID:25489788

  17. The anderson's rotating interferometer and its application to binary star measurements. (French Title: L'interféromètre à rotation de john august anderson (1876-1956) et son application - la tentative de résolution de nouvelles binaires)

    NASA Astrophysics Data System (ADS)

    Bonneau, D.

    2011-12-01

    Following the tests of interferometric observations carried out by Albert A. Michelson with the 2.5 m telescope of the Mount Wilson, George. E. Hale thinks that this technique could be applied to the measurement of close double stars. He asks John A. Anderson to produce an instrument allowing such measurements. The principle of the ocular rotating interferometer and the way of using it for the measurement of double stars are first described. Then the effects of atmospheric dispersion on the observation of the stellar interference fringes and the remedy that Anderson implements to compensate it are described. Images of the Anderson's interferometer are used to present the instrument and to describe its operation. Installed at the 2,5 m telescope, this instrument was used by Anderson and Paul W. Merrill to resolve the spectroscopic binary Capella for the first time, like a 'visual binary'. Moreover, Merrill took the measurement of two difficult visual pairs discovered by Aitken (kap UMa = A 1585 and nu2 Boo = A 1634) and tried to resolve some new visual binaries among stars known as binary spectroscopic, stars with composite spectra, variable stars and some bright stars, which led him to publish a list of 73 stars finally found simple. Finally, the remarks made by Merrill in conclusion of his work will be analyzed.

  18. Exciton-like electromagnetic excitations in non-ideal microcavity supercrystals

    PubMed Central

    Rumyantsev, Vladimir; Fedorov, Stanislav; Gumennyk, Kostyantyn; Sychanova, Marina; Kavokin, Alexey

    2014-01-01

    We study localized photonic excitations in a quasi-two-dimensional non-ideal binary microcavity lattice with use of the virtual crystal approximation. The effect of point defects (vacancies) on the excitation spectrum is investigated by numerical modelling. We obtain the dispersion and the energy gap of the electromagnetic excitations which may be considered as Frenkel exciton-like quasiparticles and analyze the dependence of their density of states on the defect concentrations in a microcavity supercrystal. PMID:25374150

  19. Excitation of channel plasmons in V-shaped grooves in the Kretschmann configuration

    NASA Astrophysics Data System (ADS)

    Ignatov, A. I.; Merzlikin, A. M.; Baryshev, A. V.; Zablotskiy, A. V.; Kuzin, A. A.

    2016-01-01

    Excitation of channel plasmons in a 1D array of V-shaped grooves in a metal film in the Kretschmann configuration was theoretically investigated. The channel plasmons were shown to be excited by the s-polarized incident wave. The excitation of channel plasmons in every single groove of the array manifested itself in a local minimum in the angular spectrum of reflection from the array of the grooves.

  20. High-energy spin and charge excitations in electron-doped copper oxide superconductors.

    PubMed

    Ishii, K; Fujita, M; Sasaki, T; Minola, M; Dellea, G; Mazzoli, C; Kummer, K; Ghiringhelli, G; Braicovich, L; Tohyama, T; Tsutsumi, K; Sato, K; Kajimoto, R; Ikeuchi, K; Yamada, K; Yoshida, M; Kurooka, M; Mizuki, J

    2014-01-01

    The evolution of electronic (spin and charge) excitations upon carrier doping is an extremely important issue in superconducting layered cuprates and the knowledge of its asymmetry between electron- and hole-dopings is still fragmentary. Here we combine X-ray and neutron inelastic scattering measurements to track the doping dependence of both spin and charge excitations in electron-doped materials. Copper L3 resonant inelastic X-ray scattering spectra show that magnetic excitations shift to higher energy upon doping. Their dispersion becomes steeper near the magnetic zone centre and they deeply mix with charge excitations, indicating that electrons acquire a highly itinerant character in the doped metallic state. Moreover, above the magnetic excitations, an additional dispersing feature is observed near the ?-point, and we ascribe it to particle-hole charge excitations. These properties are in stark contrast with the more localized spin excitations (paramagnons) recently observed in hole-doped compounds even at high doping levels. PMID:24762677

  1. From Fixed-Energy Localization Analysis to Dynamical Localization: An Elementary Path

    NASA Astrophysics Data System (ADS)

    Chulaevsky, Victor

    2014-03-01

    We review several techniques initiated by a remarkable work written by Spencer (J Stat Phys 51:1009-1019, 1988) a quarter of century ago, used and further developed in numerous subsequent researches. We also describe a fairly general, elementary derivation of spectral and strong dynamical Anderson localization from the fixed-energy analysis of the Green's functions on locally finite graphs of polynomial growth, obtained either by the multi-scale analysis or by the fractional-moment method. This derivation goes in the same direction as the Simon-Wolf method (Commun Pure Appl Math 39:75-90, 1986), but provides more quantitative estimates, can be adapted to multi-particle models and, combined with a simplified variant of the Germinet-Klein argument (Commun Math Phys 222:415-448, 2001), results in an elementary proof of strong dynamical localization on arbitrary graphs of polynomial growth.

  2. Wavetrain response of an excitable medium to local stochastic forcing

    E-print Network

    DeVille, Lee

    of structures even in one dimension; in particular, they support traveling waves. The proper- ties settles down to a series of traveling pulses whose boundaries can be modeled by moving interfaces [14, 1 in the forcing. 1 #12;On the other hand, it is also known that, in finite-dimensional systems at least, coherence

  3. Gray-body factor and infrared divergences in 1D BEC acoustic black holes Paul R. Anderson,1,*

    E-print Network

    Anderson, Paul R.

    Gray-body factor and infrared divergences in 1D BEC acoustic black holes Paul R. Anderson,1) It is shown that the gray-body factor for a one-dimensional elongated Bose-Einstein condensate (BEC) acoustic in contrast with the case of a Schwarzschild black hole where the gray-body factor vanishes as 0

  4. Identification and Analysis of Learning Preferences of Mentally Ill Adults in Rehabilitative Psychosocial Therapy at the Anderson Mental Health Center.

    ERIC Educational Resources Information Center

    Newman, Michael K.

    A study identified and analyzed the learning preferences of 17 seriously and chronically mentally ill adults participating in the rehabilitative psychosocial therapy program at the Toxaway Church Site of the Anderson Mental Health Center. Staff perceived as boring and unfocused the traditional treatment approach that relied mainly upon…

  5. Improving Smart Card Security using Self-timed Circuits Simon Moore, Ross Anderson, Paul Cunningham, Robert Mullins, George Taylor

    E-print Network

    Moore, Simon

    Improving Smart Card Security using Self-timed Circuits Simon Moore, Ross Anderson, Paul Cunningham for constructing smart card functions that are resistant to side channel attacks and fault injection. A novel alarm propagation technique is also introduced. These techniques have been used to produce a prototype smart card

  6. Program Spotlight: University of Puerto Rico and MD Anderson Partnership Welcomes Its First Graduates, Dedicated to Researching Cancer Health Disparities

    Cancer.gov

    CRCHD joins the Principal Investigators and Diversity Training co-leaders of the University of Puerto Rico and the University of Texas MD Anderson Cancer Center U54 Partnership for Excellence in Cancer Research in congratulating its first MDPhD graduates Sergei Gumá-de La Vega and Nahir Cortés-Santiago.

  7. Effects of quantized scalar fields in cosmological spacetimes with big rip singularities Jason D. Bates* and Paul R. Anderson

    E-print Network

    Anderson, Paul R.

    time the phantom energy density will become infi- nite and the Universe will expand by an infinite that as the Universe expands the phantom energy density increases with the result that in a finite amount of proper. Bates* and Paul R. Anderson Department of Physics, Wake Forest University, Winston-Salem, North Carolina

  8. Interactive Pen-and-Ink Illustration Michael P. Salisbury Sean E. Anderson Ronen Barzel3 David H. Salesin

    E-print Network

    Washington at Seattle, University of

    Interactive Pen-and-Ink Illustration Michael P. Salisbury Sean E. Anderson Ronen Barzel3 David H for creating pen-and-ink illustra- tions. The system uses stroke textures--collections of strokes ar- ranged-photorea- listic rendering, prioritized stroke textures. 1 Introduction Pen-and-ink is an extremely limited medium

  9. Scale-Dependent Reproduction of Pen-and-Ink Illustrations Mike Salisbury Corin Anderson Dani Lischinski David H. Salesin

    E-print Network

    Meenakshisundaram, Gopi

    Scale-Dependent Reproduction of Pen-and-Ink Illustrations Mike Salisbury Corin Anderson Dani This paper describes a representation for pen-and-ink illustrations that allows the creation of high-fidelity illustrations at any scale or resolution. We represent a pen-and-ink illustration as a low-reso- lution grey

  10. Measurements of Vapor Flow Regimes in Liquid Metal Pools M.H. ANDERSON, M. L. CORRADINI, R. BONAZZA

    E-print Network

    California at Los Angeles, University of

    Measurements of Vapor Flow Regimes in Liquid Metal Pools M.H. ANDERSON, M. L. CORRADINI, R. BONAZZA fractions within a pool of low-density liquid metal (NaK) during gas injection inside a horizontal magnetic from 0 to 5 SCFH (0 liquid metal, flow regimes 1

  11. www.water-alternatives.org Volume 7 | Issue 2 Bauer, C. 2014. Book review of Anderson et al. 2012.

    E-print Network

    restrictions on private transfers] 6. Privatising in-stream flows [including water pollution issues] 7www.water-alternatives.org Volume 7 | Issue 2 Bauer, C. 2014. Book review of Anderson et al. 2012. Tapping water markets. RFF Press/Routledge. Water Alternatives 7(2): 436-438 Book Review: Tapping water

  12. Cluster I/O with River: Making the Fast Case Common Remzi H. ArpaciDusseau, Eric Anderson, Noah Treuhaft,

    E-print Network

    Yelick, Katherine

    Cluster I/O with River: Making the Fast Case Common Remzi H. Arpaci­Dusseau, Eric Anderson, Noah University of California, Berkeley Abstract We introduce River, a data­flow programming environment and I/O substrate for clusters of computers. River is designed to provide max­ imum performance in the common case

  13. Cluster I/O with River: Making the Fast Case Common Remzi H. Arpaci-Dusseau, Eric Anderson, Noah Treuhaft,

    E-print Network

    California at Berkeley, University of

    Cluster I/O with River: Making the Fast Case Common Remzi H. Arpaci-Dusseau, Eric Anderson, Noah University of California, Berkeley Abstract We introduce River, a data-flow programming environ- ment and I/O substrate for clusters of computers. River is designed to provide maximum performance in the common case

  14. Cluster I/O with River: Making the Fast Case Common Remzi H. Arpaci-Dusseau, Eric Anderson, Noah Treuhaft,

    E-print Network

    Arpaci-Dusseau, Remzi

    Cluster I/O with River: Making the Fast Case Common Remzi H. Arpaci-Dusseau, Eric Anderson, Noah University of California, Berkeley ¢¡¤£¦¥¦§©¨¤¥ We introduce River, a data-flow programming environment and I/O substrate for clusters of computers. River is designed to provide max- imum performance

  15. 77 FR 72906 - Chessie Logistics Co., LLC-Acquisition and Operation Exemption-J. Emil Anderson & Son, Inc.

    Federal Register 2010, 2011, 2012, 2013, 2014

    2012-12-06

    ... Surface Transportation Board Chessie Logistics Co., LLC--Acquisition and Operation Exemption-- J. Emil Anderson & Son, Inc. Chessie Logistics Co., LLC (Chessie), a noncarrier, has filed a verified notice of... copy of each pleading must be served on Ariel A. Erbacher, Legal Counsel, Chessie Logistics Co.,...

  16. 10 CFR 8.2 - Interpretation of Price-Anderson Act, section 170 of the Atomic Energy Act of 1954.

    Code of Federal Regulations, 2010 CFR

    2010-01-01

    ... in Nuclear Energy 75 (1959). In the testimony before the Joint Committee last year, Professor Samuel... 10 Energy 1 2010-01-01 2010-01-01 false Interpretation of Price-Anderson Act, section 170 of the Atomic Energy Act of 1954. 8.2 Section 8.2 Energy NUCLEAR REGULATORY COMMISSION INTERPRETATIONS §...

  17. 10 CFR 8.2 - Interpretation of Price-Anderson Act, section 170 of the Atomic Energy Act of 1954.

    Code of Federal Regulations, 2012 CFR

    2012-01-01

    ... in Nuclear Energy 75 (1959). In the testimony before the Joint Committee last year, Professor Samuel... 10 Energy 1 2012-01-01 2012-01-01 false Interpretation of Price-Anderson Act, section 170 of the Atomic Energy Act of 1954. 8.2 Section 8.2 Energy NUCLEAR REGULATORY COMMISSION INTERPRETATIONS §...

  18. 10 CFR 8.2 - Interpretation of Price-Anderson Act, section 170 of the Atomic Energy Act of 1954.

    Code of Federal Regulations, 2011 CFR

    2011-01-01

    ... in Nuclear Energy 75 (1959). In the testimony before the Joint Committee last year, Professor Samuel... 10 Energy 1 2011-01-01 2011-01-01 false Interpretation of Price-Anderson Act, section 170 of the Atomic Energy Act of 1954. 8.2 Section 8.2 Energy NUCLEAR REGULATORY COMMISSION INTERPRETATIONS §...

  19. HighPerformance I/O and Networking Software in Sequoia 2000 Joseph Pasquale, Eric Anderson, Kevin Fall, Jonathan Kay

    E-print Network

    Polyzos, George C.

    Page 1 High­Performance I/O and Networking Software in Sequoia 2000 Joseph Pasquale, Eric Anderson}@cs.ucsd.edu Abstract We describe our experiences producing high­speed network and I/O software in the Sequoia 2000, is a key requirement for Sequoia distributed applications. We present new designs and implementations

  20. Managing Energy and Server Resources in Hosting Centers Jeffrey S. Chase, Darrell C. Anderson, Prachi N. Thakar, Amin M. Vahdat

    E-print Network

    Vahdat, Amin

    Managing Energy and Server Resources in Hosting Centers Jeffrey S. Chase, Darrell C. Anderson approach to managing shared server resources, in which services "bid" for resources as a func- tion data centers managed by third-party hosting providers. Managed hosting in shared centers offers

  1. Genomic organization and reproductive regulation of a carrier/storage protein in the Varroa Mite, Varroa destructor (Anderson & Trueman)

    Technology Transfer Automated Retrieval System (TEKTRAN)

    The complete genomic region and corresponding transcript of the most abundant protein in the phoretic varroa mite, Varroa destructor (Anderson & Trueman), were sequenced and found to be homologous with hemelipoglyco-proteins (HeLP/CP) of acarines. The genomic arrangement showed the presence of 14 in...

  2. A versatile and highly efficient post-functionalization method for grafting organic molecules onto Anderson-type polyoxometalates.

    PubMed

    Vanhaecht, Stef; Jacobs, Jeroen; Van Meervelt, Luc; Parac-Vogt, Tatjana N

    2015-11-28

    A new azide functionalized Anderson polyoxometalate was synthesized, fully characterized and subsequently used as a building block for further POM post-functionalization with organic compounds through a copper catalyzed azide-alkyne cycloaddition (CuAAC) reaction. Optimization of the reaction conditions led to an efficient, fast, convenient and versatile POM coupling method. PMID:26486549

  3. Eternal inflation and localization on the landscape

    SciTech Connect

    Podolsky, Dmitry; Enqvist, Kari E-mail: kari.enqvist@helsinki.fi

    2009-02-15

    We model essential features of eternal inflation on the landscape of a dense discretuum of vacua by the potential V({phi}) = V{sub 0}+{delta}V({phi}), where |{delta}V({phi})| << V{sub 0} is random. We find that the diffusion of the distribution function {rho}({phi},t) of the inflaton expectation value in different Hubble patches may be suppressed due to the effect analogous to the Anderson localization in disordered quantum systems. At late times only the localized part of the distribution function {rho}({phi},t) survives which leads to dynamical selection principle on the landscape. As a result, there exist such islands on the landscape that the probability to measure any but a small value of the cosmological constant in a given Hubble patch is exponentially suppressed.

  4. Plasmonic excitations in ultrathin metal films on dielectric substrates

    NASA Astrophysics Data System (ADS)

    Li, Xiaoguang; Teng, Ao; Özer, Mustafa M.; Shen, Jian; Weitering, Hanno H.; Zhang, Zhenyu

    2014-06-01

    The optical properties of metals are mainly determined by their plasmonic excitations, with various intriguing phenomena associated with systems in reduced dimensions. In this paper, we present a systematic study of the plasmonic excitations in ultrathin metal films on dielectric substrates using two different theoretical approaches, and with Mg thin films on Si as prototype systems. The bulk of the results are obtained using the first approach within first-principles time-dependent local density approximation. We show that the presence of the substrate substantially modifies the plasmon hybridization of the metal films; in turn, the plasmon excitation in the films strongly enhances the absorption of the substrate. The detailed absorption spectra contain several intriguing features. Above the Mg surface plasmon mode, we observe a broad resonance due to the hybridization between the antisymmetric surface plasmon and multipole surface plasmon. Furthermore, below the Mg surface plasmon mode, there also exists a broad absorption feature, caused by individual electron-hole pair excitations. In the second approach, we use a semi-classical local optics model to reveal an intrinsic connection between the broad absorption feature and the multipole surface plasmon modes, which result from the single-particle and collective excitations of the same surface electrons, respectively. Our theoretical predictions on the plasmon dispersions and absorption spectra are also shown to be qualitatively consistent with the latest experimental observations using electron energy loss spectroscopy for Mg thin films grown on Si substrates.

  5. Industrial applications of photonuclear resonance excitation

    E-print Network

    Chichester, David Lee, 1971-

    2000-01-01

    Photonuclear resonance excitation refers to a variety of photonuclear interaction processes that lead to the excitation of a nucleus from some initial state to a higher energy nuclear state. Typical excited nuclear state ...

  6. 46 CFR 111.12-3 - Excitation.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ...ELECTRICAL ENGINEERING ELECTRIC SYSTEMS-GENERAL REQUIREMENTS Generator Construction and Circuits § 111.12-3 Excitation...no static exciter may be used for excitation of an emergency generator unless it is provided with a permanent magnet or a...

  7. Parametric Excitation of a DWSC 

    E-print Network

    Lakhotia, Chandan

    2011-08-08

    Parametric excitation of the DWSC (Deep Water Stable Craneship) is studied in this thesis. It occurs for a system without any external forcing, when one of the coefficients in the equation of motion (EOM) modeling the system varies with time...

  8. The Ce 4{ital f} surface shift: A test for the Anderson-impurity Hamiltonian

    SciTech Connect

    Duo, L.; De Rossi, S.; Vavassori, P.; Ciccacci, F.; Olcese, G.L.; Chiaia, G.; Lindau, I.

    1996-12-01

    Evidence is provided of the role of the different hybridization strengths between the surface and the bulk in determining the magnitude of the surface shift for the shallow Ce 4{ital f} levels, with respect to the deeper core levels. This was achieved by comparing the photoemission core levels for a weakly hybridized case (CeAl) to a case of intermediate hybridization ({gamma}-Ce). For CeAl a 4{ital f} surface shift of 0.45 eV was observed, similar to that for the 5{ital p} core level, whereas a smaller (if any) 4{ital f} surface shift was observed for {gamma}-Ce. Model calculations based on the Anderson impurity Hamiltonian are shown to give a correct evaluation of this effect, which can be exploited as a way of testing the results of such a description for the Ce {ital f} states. {copyright} {ital 1996 The American Physical Society.}

  9. Decay of a nonlinear impurity in a structured continuum from a nonlinear Fano-Anderson model

    SciTech Connect

    Longhi, Stefano

    2007-05-01

    The decay dynamics of a nonlinear impurity mode embedded in a linear structured continuum is theoretically investigated in the framework of a nonlinear Fano-Anderson model. A gradient flow dynamics for the survival probability is derived in the Van Hove ({lambda}{sup 2}t) limit by a multiple-scale asymptotic analysis, and the role of nonlinearity on the decay law is discussed. In particular, it is shown that the existence of bound states embedded in the continuum acts as transient trapping states which slow down the decay. The dynamical behavior predicted in the {lambda}{sup 2}t limit is studied in detail for a simple tight-binding one-dimensional lattice model, which may describe electron or photon transport in condensed matter or photonic systems. Numerical simulations of the underlying equations confirm, in particular, the trapping effect in the decay process due to bound states embedded in the continuum.

  10. Leggett Modes and the Anderson-Higgs Mechanism in Superconductors without Inversion Symmetry

    NASA Astrophysics Data System (ADS)

    Bittner, Nikolaj; Einzel, Dietrich; Klam, Ludwig; Manske, Dirk

    2015-11-01

    We develop a microscopic and gauge-invariant theory for collective modes resulting from the phase of the superconducting order parameter in noncentrosymmetric superconductors. Considering various crystal symmetries, we derive the corresponding gauge mode ?G(q ) and find, in particular, new Leggett modes ?L(q ) with characteristic properties that are unique to noncentrosymmetric superconductors. We calculate their mass and dispersion that reflect the underlying spin-orbit coupling and thus the balance between triplet and singlet superconductivity occurring simultaneously. Finally, we demonstrate the role of the Anderson-Higgs mechanism: while the long-range Coulomb interaction shifts ?G(q ) to the condensate plasma mode ?P(q ), it leaves the mass ?0 of the new Leggett mode unaffected and only slightly modifies its dispersion.

  11. Classical mapping for Hubbard operators: Application to the double-Anderson model

    SciTech Connect

    Li, Bin; Miller, William H.; Levy, Tal J.; Rabani, Eran

    2014-05-28

    A classical Cartesian mapping for Hubbard operators is developed to describe the nonequilibrium transport of an open quantum system with many electrons. The mapping of the Hubbard operators representing the many-body Hamiltonian is derived by using analogies from classical mappings of boson creation and annihilation operators vis-à-vis a coherent state representation. The approach provides qualitative results for a double quantum dot array (double Anderson impurity model) coupled to fermionic leads for a range of bias voltages, Coulomb couplings, and hopping terms. While the width and height of the conduction peaks show deviations from the master equation approach considered to be accurate in the limit of weak system-leads couplings and high temperatures, the Hubbard mapping captures all transport channels involving transition between many electron states, some of which are not captured by approximate nonequilibrium Green function closures.

  12. Extended recursion in operator space (EROS), a new impurity solver for the single impurity Anderson model

    SciTech Connect

    Albers, Robert C; Julien, Jean P

    2008-01-01

    We have developed a new efficient and accurate impurity solver for the single impurity Anderson model (SIAM), which is based on a non-perturbative recursion technique in a space of operators and involves expanding the self-energy as a continued fraction. The method has no special occupation number or temperature restrictions; the only approximation is the number of levels of the continued fraction retained in the expansion. We also show how this approach can be used as a new approach to Dynamical Mean Field Theory (DMTF) and illustrate this with the Hubbard model. The three lowest orders of recursion give the Hartree-Fock, Hubbard I, and Hubbard III approximations. A higher level of recursion is able to reproduce the expected 3-peak structure in the spectral function and Fermi liquid behavior.

  13. High-order terms in the renormalized perturbation theory for the Anderson impurity model

    NASA Astrophysics Data System (ADS)

    Pandis, Vassilis; Hewson, Alex C.

    2015-09-01

    We study the renormalized perturbation theory of the single-impurity Anderson model, particularly the high-order terms in the expansion of the self-energy in powers of the renormalized coupling U ˜. Though the presence of counterterms in the renormalized theory may appear to complicate the diagrammatics, we show how these can be seamlessly accommodated by carrying out the calculation order-by-order in terms of skeleton diagrams. We describe how the diagrams pertinent to the renormalized self-energy and four vertex can be automatically generated, translated into integrals, and numerically integrated. To maximize the efficiency of our approach we introduce a generalized k -particle/hole propagator, which is used to analytically simplify the resultant integrals and reduce the dimensionality of the integration. We present results for the self-energy and spectral density to fifth order in U ˜, for various values of the model asymmetry, and compare them to a numerical renormalization group calculation.

  14. Multi-Overlap Simulations of the $3d$ Edwards-Anderson Ising Spin Glass

    E-print Network

    Bernd A. Berg; Wolfhard Janke

    1997-12-30

    We introduce a novel method for numerical spin glass investigations: Simulations of two replica at fixed temperature, weighted such that a broad distribution of the Parisi overlap parameter $q$ is achieved. Canonical expectation values for the entire $q$-range (multi-overlap) follow by re-weighting. We demonstrate the feasibility of the approach by studying the $3d$ Edwards-Anderson Ising ($J_{ik}=\\pm 1$) spin glass in the broken phase ($\\beta=1$). For the first time it becomes possible to obtain reliable results about spin glass tunneling barriers. In addition, as do some earlier numerical studies, our results support that Parisi mean field theory is valid down to $3d$.

  15. Modified Anderson-Darling Test-Based Target Detector in Non-Homogenous Environments

    PubMed Central

    Li, Yang; Wei, Yinsheng; Li, Bingfei; Alterovitz, Gil

    2014-01-01

    A constant false alarm rate (CFAR) target detector in non-homogenous backgrounds is proposed. Based on K-sample Anderson-Darling (AD) tests, the method re-arranges the reference cells by merging homogenous sub-blocks surrounding the cell under test (CUT) into a new reference window to estimate the background statistics. Double partition test, clutter edge refinement and outlier elimination are used as an anti-clutter processor in the proposed Modified AD (MAD) detector. Simulation results show that the proposed MAD test based detector outperforms cell-averaging (CA) CFAR, greatest of (GO) CFAR, smallest of (SO) CFAR, order-statistic (OS) CFAR, variability index (VI) CFAR, and CUT inclusive (CI) CFAR in most non-homogenous situations. PMID:25177800

  16. d -wave superconductivity in the frustrated two-dimensional periodic Anderson model

    NASA Astrophysics Data System (ADS)

    Wu, Wei; Tremblay, A.-M.-S.

    2015-01-01

    Superconductivity in heavy-fermion materials can sometimes appear in the incoherent regime and in proximity to an antiferromagnetic quantum critical point. Here, we study these phenomena using large-scale determinant quantum Monte Carlo simulations and the dynamical cluster approximation with various impurity solvers for the periodic Anderson model with frustrated hybridization. We obtain solid evidence for a dx2-y2 superconducting phase arising from an incoherent normal state in the vicinity of an antiferromagnetic quantum critical point. There is a coexistence region, and the width of the superconducting dome increases with frustration. Through a study of the pairing dynamics, we find that the retarded spin fluctuations give the main contribution to the pairing glue. These results are relevant for unconventional superconductivity in the Ce-115 family of heavy fermions.

  17. Leveraging Anderson Acceleration for improved convergence of iterative solutions to transport systems

    SciTech Connect

    Willert, Jeffrey; Taitano, William T.; Knoll, Dana

    2014-09-15

    In this note we demonstrate that using Anderson Acceleration (AA) in place of a standard Picard iteration can not only increase the convergence rate but also make the iteration more robust for two transport applications. We also compare the convergence acceleration provided by AA to that provided by moment-based acceleration methods. Additionally, we demonstrate that those two acceleration methods can be used together in a nested fashion. We begin by describing the AA algorithm. At this point, we will describe two application problems, one from neutronics and one from plasma physics, on which we will apply AA. We provide computational results which highlight the benefits of using AA, namely that we can compute solutions using fewer function evaluations, larger time-steps, and achieve a more robust iteration.

  18. Exciting Polaritons with Quantum Light

    NASA Astrophysics Data System (ADS)

    López Carreño, J. C.; Sánchez Muñoz, C.; Sanvitto, D.; del Valle, E.; Laussy, F. P.

    2015-11-01

    We discuss the excitation of polaritons—strongly coupled states of light and matter—by quantum light, instead of the usual laser or thermal excitation. As one illustration of the new horizons thus opened, we introduce "Mollow spectroscopy"—a theoretical concept for a spectroscopic technique that consists of scanning the output of resonance fluorescence onto an optical target—from which weak nonlinearities can be read with high precision even in strongly dissipative environments.

  19. Laser-induced nuclear excitation

    SciTech Connect

    Zon, B. A. Kornev, A. S.

    2010-05-15

    An analysis is presented of the Coulomb excitation of low-lying nuclear levels by the electrons produced by strong-field ionization of atoms. It is shown that the resulting short-lived radioactivity can be as high as on the order of 10{sup 3} Ci for certain isotopes excited by using modern laser systems. Relativistic effects are demonstrated that substantially increase radioactivity as compared to that predicted by nonrelativistic theory results.

  20. Nonequilibrium dynamics of a singlet-triplet Anderson impurity near the quantum phase transition.

    PubMed

    Roura Bas, P; Aligia, A A

    2010-01-20

    We study the singlet-triplet Anderson model (STAM) in which a configuration with a doublet is hybridized with another containing a singlet and a triplet, as a minimal model to describe two-level quantum dots coupled to two metallic leads in effectively a one-channel fashion. The model has a quantum phase transition which separates regions of a doublet and a singlet ground state. The limits of integer valence of the STAM (which include a model similar to the underscreened spin-1 Kondo model) are derived and used to predict the behavior of the conductance through the system on both sides of the transition, where it jumps abruptly. At a special quantum critical line, the STAM can be mapped to an infinite- U ordinary Anderson model (OAM) plus a free spin 1/2. We use this mapping to obtain the spectral densities of the STAM as a function of those of the OAM at the transition. Using the non-crossing approximation (NCA), we calculate the spectral densities and conductance through the system as a function of temperature and bias voltage, and determine the changes that take place at the quantum phase transition. The separation of the spectral density into a singlet and a triplet part allows us to shed light on the underlying physics and to explain a shoulder observed recently in the zero bias conductance as a function of temperature in transport measurements through a single fullerene molecule (Roch et al 2008 Nature 453 633). The structure with three peaks observed in nonequilibrium transport in these experiments is also explained. PMID:21386260

  1. Electron-excited molecule interactions

    SciTech Connect

    Christophorou, L.G. Tennessee Univ., Knoxville, TN . Dept. of Physics)

    1991-01-01

    In this paper the limited but significant knowledge to date on electron scattering from vibrationally/rotationally excited molecules and electron scattering from and electron impact ionization of electronically excited molecules is briefly summarized and discussed. The profound effects of the internal energy content of a molecule on its electron attachment properties are highlighted focusing in particular on electron attachment to vibrationally/rotationally and to electronically excited molecules. The limited knowledge to date on electron-excited molecule interactions clearly shows that the cross sections for certain electron-molecule collision processes can be very different from those involving ground state molecules. For example, optically enhanced electron attachment studies have shown that electron attachment to electronically excited molecules can occur with cross sections 10{sup 6} to 10{sup 7} times larger compared to ground state molecules. The study of electron-excited molecule interactions offers many experimental and theoretical challenges and opportunities and is both of fundamental and technological significance. 54 refs., 15 figs.

  2. Redox Control of Cardiac Excitability

    PubMed Central

    Aggarwal, Nitin T.

    2013-01-01

    Abstract Reactive oxygen species (ROS) have been associated with various human diseases, and considerable attention has been paid to investigate their physiological effects. Various ROS are synthesized in the mitochondria and accumulate in the cytoplasm if the cellular antioxidant defense mechanism fails. The critical balance of this ROS synthesis and antioxidant defense systems is termed the redox system of the cell. Various cardiovascular diseases have also been affected by redox to different degrees. ROS have been indicated as both detrimental and protective, via different cellular pathways, for cardiac myocyte functions, electrophysiology, and pharmacology. Mostly, the ROS functions depend on the type and amount of ROS synthesized. While the literature clearly indicates ROS effects on cardiac contractility, their effects on cardiac excitability are relatively under appreciated. Cardiac excitability depends on the functions of various cardiac sarcolemal or mitochondrial ion channels carrying various depolarizing or repolarizing currents that also maintain cellular ionic homeostasis. ROS alter the functions of these ion channels to various degrees to determine excitability by affecting the cellular resting potential and the morphology of the cardiac action potential. Thus, redox balance regulates cardiac excitability, and under pathological regulation, may alter action potential propagation to cause arrhythmia. Understanding how redox affects cellular excitability may lead to potential prophylaxis or treatment for various arrhythmias. This review will focus on the studies of redox and cardiac excitation. Antioxid. Redox Signal. 18, 432–468. PMID:22897788

  3. Suppression and Revival of Weak Localization through Control of Time-Reversal Symmetry.

    PubMed

    Müller, K; Richard, J; Volchkov, V V; Denechaud, V; Bouyer, P; Aspect, A; Josse, V

    2015-05-22

    We report on the observation of suppression and revival of coherent backscattering of ultracold atoms launched in an optical disorder in a quasi-2D geometry and submitted to a short dephasing pulse, as proposed by Micklitz, Müller, and Altland [Phys. Rev. B 91, 064203 (2015)]. This observation demonstrates a novel and general method to study weak localization by manipulating time reversal symmetry in disordered systems. In future experiments, this scheme could be extended to investigate higher order localization processes at the heart of Anderson (strong) localization. PMID:26047238

  4. Topological excitations in a kagome magnet.

    PubMed

    Pereiro, Manuel; Yudin, Dmitry; Chico, Jonathan; Etz, Corina; Eriksson, Olle; Bergman, Anders

    2014-01-01

    Chirality--that is, left or right handedness--is present in many scientific areas, and particularly in condensed matter physics. Inversion symmetry breaking relates chirality with skyrmions, which are protected field configurations with particle-like and topological properties. Here we show that a kagome magnet, with Heisenberg and Dzyaloshinskii-Moriya interactions, causes non-trivial topological and chiral magnetic properties. We also find that under special circumstances, skyrmions emerge as excitations, having stability even at room temperature. Chiral magnonic edge states of a kagome magnet offer, in addition, a promising way to create, control and manipulate skyrmions. This has potential for applications in spintronics, that is, for information storage or as logic devices. Collisions between these particle-like excitations are found to be elastic at very low temperature in the skyrmion-skyrmion channel, albeit without mass-conservation. Skyrmion-antiskyrmion collisions are found to be more complex, where annihilation and creation of these objects have a distinct non-local nature. PMID:25198354

  5. 46 CFR 111.12-3 - Excitation.

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ... (incorporated by reference; see 46 CFR 110.10-1), except that those for mobile offshore drilling units must meet... 46 CFR 110.10-1). In particular, no static exciter may be used for excitation of an emergency... REQUIREMENTS Generator Construction and Circuits § 111.12-3 Excitation. In general, excitation must...

  6. 46 CFR 111.12-3 - Excitation.

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ... (incorporated by reference; see 46 CFR 110.10-1), except that those for mobile offshore drilling units must meet... 46 CFR 110.10-1). In particular, no static exciter may be used for excitation of an emergency... REQUIREMENTS Generator Construction and Circuits § 111.12-3 Excitation. In general, excitation must...

  7. 46 CFR 111.12-3 - Excitation.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... (incorporated by reference; see 46 CFR 110.10-1), except that those for mobile offshore drilling units must meet... 46 CFR 110.10-1). In particular, no static exciter may be used for excitation of an emergency... REQUIREMENTS Generator Construction and Circuits § 111.12-3 Excitation. In general, excitation must...

  8. 46 CFR 111.12-3 - Excitation.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... (incorporated by reference; see 46 CFR 110.10-1), except that those for mobile offshore drilling units must meet... 46 CFR 110.10-1). In particular, no static exciter may be used for excitation of an emergency... REQUIREMENTS Generator Construction and Circuits § 111.12-3 Excitation. In general, excitation must...

  9. 46 CFR 111.12-3 - Excitation.

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ... (incorporated by reference; see 46 CFR 110.10-1), except that those for mobile offshore drilling units must meet... 46 CFR 110.10-1). In particular, no static exciter may be used for excitation of an emergency... REQUIREMENTS Generator Construction and Circuits § 111.12-3 Excitation. In general, excitation must...

  10. Nanoparticles inside nanodishes for plasmon excitations

    NASA Astrophysics Data System (ADS)

    Wi, Jung-Sub; Son, Jin Gyeong; Han, Sang Woo; Lee, Tae Geol

    2015-11-01

    We demonstrate a simple route to hybridize two different nanomaterials by using three-dimensional nanodishes that can serve as small plasmonic containers to host guest nanoparticles. The nanodishes were fabricated using nanoimprint lithography and oblique-angle film deposition, and the guest nanoparticles were drop-cast onto the host nanodishes. Based on the proposed method, colloidal Au nanoparticles were assembled inside the Au nanodishes in the form of a labyrinth. These Au nanoparticle-nanodish hybrids excited a strong surface plasmon resonance, as verified by a numerical simulation of the local field enhancement and by direct observation of both the enhanced Raman signals and photochemical reactions. Our results point to the potential of the nanodishes as a useful platform for combining diverse nanomaterials and their functionalities.

  11. Single molecule photoluminescence excitation spectroscopy of polyfluorene

    NASA Astrophysics Data System (ADS)

    da Como, Enrico; Lupton, John

    2010-03-01

    Polyfluorene is a remarkable conjugated polymer with a uniquely rich polymorphism [1]. Because of this characteristic it can be considered as a model playground to understand structure-property relationships in conjugated polymers. Here, by low temperature single polymer chain photoluminescence excitation spectroscopy [2], we look at the spectral characteristics of the absorbing and emitting chromophores on a chain. These experiments are performed on both the ?-phase and the glassy disordered structure, elucidating the role of chain polymorphism on conformational relaxation and energy transfer. Moreover, we compare results on multichromophoric polymers with short oligomers, where a single chromophore is responsible for the optical response. These experiments illuminate directly the emergence of chromophores in conjugated polymers through delocalization: how a pi-electron system evolves from a localized molecular (oligomeric) unit into a delocalized species. [4pt] [1] Da Como Nano Lett. [0pt] [2] Walter PRL 2009

  12. Indirect excitation of ultrafast demagnetization.

    PubMed

    Vodungbo, Boris; Tudu, Bahrati; Perron, Jonathan; Delaunay, Renaud; Müller, Leonard; Berntsen, Magnus H; Grübel, Gerhard; Malinowski, Grégory; Weier, Christian; Gautier, Julien; Lambert, Guillaume; Zeitoun, Philippe; Gutt, Christian; Jal, Emmanuelle; Reid, Alexander H; Granitzka, Patrick W; Jaouen, Nicolas; Dakovski, Georgi L; Moeller, Stefan; Minitti, Michael P; Mitra, Ankush; Carron, Sebastian; Pfau, Bastian; von Korff Schmising, Clemens; Schneider, Michael; Eisebitt, Stefan; Lüning, Jan

    2016-01-01

    Does the excitation of ultrafast magnetization require direct interaction between the photons of the optical pump pulse and the magnetic layer? Here, we demonstrate unambiguously that this is not the case. For this we have studied the magnetization dynamics of a ferromagnetic cobalt/palladium multilayer capped by an IR-opaque aluminum layer. Upon excitation with an intense femtosecond-short IR laser pulse, the film exhibits the classical ultrafast demagnetization phenomenon although only a negligible number of IR photons penetrate the aluminum layer. In comparison with an uncapped cobalt/palladium reference film, the initial demagnetization of the capped film occurs with a delayed onset and at a slower rate. Both observations are qualitatively in line with energy transport from the aluminum layer into the underlying magnetic film by the excited, hot electrons of the aluminum film. Our data thus confirm recent theoretical predictions. PMID:26733106

  13. Excitation optimization for damage detection

    SciTech Connect

    Bement, Matthew T; Bewley, Thomas R

    2009-01-01

    A technique is developed to answer the important question: 'Given limited system response measurements and ever-present physical limits on the level of excitation, what excitation should be provided to a system to make damage most detectable?' Specifically, a method is presented for optimizing excitations that maximize the sensitivity of output measurements to perturbations in damage-related parameters estimated with an extended Kalman filter. This optimization is carried out in a computationally efficient manner using adjoint-based optimization and causes the innovations term in the extended Kalman filter to be larger in the presence of estimation errors, which leads to a better estimate of the damage-related parameters in question. The technique is demonstrated numerically on a nonlinear 2 DOF system, where a significant improvement in the damage-related parameter estimation is observed.

  14. Excited-to-excited-state scattering using weak measurements

    NASA Astrophysics Data System (ADS)

    U, Satya Sainadh; Narayanan, Andal

    2015-11-01

    Weak measurements are a subset of measurement processes in quantum mechanics wherein the system, which is being measured, interacts very weakly with the measuring apparatus. Measurement values of observables undergoing a weak interaction and their amplification are concepts that have sharpened our understanding of interaction processes in quantum mechanics. Recent experiments show that naturally occurring processes such as resonance fluorescence from excited states of an atom can exhibit weak value amplification effect. In this paper we theoretically analyze the process of elastic resonance fluorescence from a V -type three-level atomic system, using the well-known Weiskopff-Wigner (WW) theory of spontaneous emission. Within this theory we show that a weak interaction regime can be identified and for suitable choices of initial and final excited states the mean scattering time between these states show an amplification effect during interaction with the vacuum bath modes of the electromagnetic field. We thus show that a system-bath interaction can show weak value amplification. Using our theory we reproduce the published experimental results carried out in such a system. More importantly, our theory can calculate scattering time scales in elastic resonance scattering between multiple excited states of a single atom or between common excited state configurations of interacting multiatom systems.

  15. Excited to excited state scattering using weak measurements

    E-print Network

    Satya Sainadh U; Andal Narayanan

    2015-11-06

    Weak measurements are a subset of measurement processes in quantum mechanics wherein the system which is being measured interacts very weakly with the measuring apparatus. Measurement values of observables undergoing a weak interaction and their amplification, are concepts that have sharpened our understanding of interaction processes in quantum mechanics. Recent experiments show that naturally occurring processes such as resonance fluorescence from excited states of an atom can exhibit weak value amplification effect. In this paper, we theoretically analyze the process of elastic resonance fluorescence from a V-type three level atomic system, using the well known Weiskopff-Wigner (W-W) theory of spontaneous emission. Within this theory, we show that, a weak interaction regime can be identified and for suitable choices of initial and final excited states, the mean scattering time between these states show an amplification effect during interaction with the vacuum bath modes of the electromagnetic field. We thus show for the first time that a system bath interaction can show weak value amplification. Using our theory we reproduce the published experimental results carried out in such a system. More importantly, our theory can calculate scattering timescales in elastic resonance scattering between multiple excited states of a single atom or between common excited state configurations of interacting multi-atom systems.

  16. Magnetically induced pulser laser excitation

    SciTech Connect

    Taylor, R.S.; Leopold, K.E.

    1985-02-15

    A novel excitation scheme has been developed for excimer discharge lasers. The technique uses pulse transformer technology to induce a fast, high voltage pulse directly onto a ground potential laser electrode resulting in the breakdown of the laser gas mix. Saturation of the pulse transformer core inductance then permits efficient energy transfer from the main energy storage circuit into the discharge. When this excitation technique was used in a XeCl laser an output energy density of 2.5 J/l and an overall electrical to optical efficiency of 2% were obtained. The technique appears promising for the development of high energy, high average power excimer lasers.

  17. Excited Fermions at H1

    E-print Network

    E. Sauvan; for the H1 Collaboration

    2007-09-05

    We present a search for excited neutrinos and electrons using all data collected by the H1 experiment at HERA at a center-of-mass energy of 320 GeV with an integrated luminosity of up to 435 pb$^{-1}$. No evidence for excited neutrino or electron production is found. Mass dependent exclusion limits are determined for the ratio of the coupling to the compositeness scale, $f/{\\Lambda}$. These limits greatly extend the excluded region to higher masses than has been possible in previous searches.

  18. Focal cortical infarcts alter intrinsic excitability and synaptic excitation in the reticular thalamic nucleus

    PubMed Central

    Paz, Jeanne T.; Christian, Catherine A.; Parada, Isabel; Prince, David A.; Huguenard, John R.

    2010-01-01

    Focal cortical injuries result in death of cortical neurons and their efferents and ultimately in death or damage of thalamocortical relay (TCR) neurons that project to the affected cortical area. Neurons of the inhibitory reticular thalamic nucleus (nRT) receive excitatory inputs from corticothalamic and thalamocortical axons and are thus denervated by such injuries, yet nRT cells generally survive these insults to a greater degree than TCR cells. nRT cells inhibit TCR cells, regulate thalamocortical transmission, and generate cerebral rhythms including those involved in thalamocortical epilepsies. The survival and reorganization of nRT following cortical injury would determine recovery of thalamocortical circuits following injury. However, the physiological properties and connectivity of the survivors remain unknown. In order to study possible alterations in nRT neurons, we used the rat photothrombosis model of cortical stroke. Using in vitro patch clamp recordings at various times following the photothrombotic injury, we show that localized strokes in the somatosensory cortex induce long-term reductions in intrinsic excitability and evoked synaptic excitation of nRT cells by the end of the first week after the injury. We find that nRT neurons in injured rats show (1) decreased membrane input resistance, (2) reduced low-threshold calcium burst responses, and (3) weaker evoked excitatory synaptic responses. Such alterations in nRT cellular excitability could lead to loss of nRT-mediated inhibition in relay nuclei, increased output of surviving TCR cells and enhanced thalamocortical excitation, which may facilitate recovery of thalamic and cortical sensory circuits. In addition, such changes could be maladaptive, leading to injury-induced epilepsy. PMID:20392967

  19. Adult neurogenesis modifies excitability of the dentate gyrus

    PubMed Central

    Ikrar, Taruna; Guo, Nannan; He, Kaiwen; Besnard, Antoine; Levinson, Sally; Hill, Alexis; Lee, Hey-Kyoung; Hen, Rene; Xu, Xiangmin; Sahay, Amar

    2013-01-01

    Adult-born dentate granule neurons contribute to memory encoding functions of the dentate gyrus (DG) such as pattern separation. However, local circuit-mechanisms by which adult-born neurons partake in this process are poorly understood. Computational, neuroanatomical and electrophysiological studies suggest that sparseness of activation in the granule cell layer (GCL) is conducive for pattern separation. A sparse coding scheme is thought to facilitate the distribution of similar entorhinal inputs across the GCL to decorrelate overlapping representations and minimize interference. Here we used fast voltage-sensitive dye (VSD) imaging combined with laser photostimulation and electrical stimulation to examine how selectively increasing adult DG neurogenesis influences local circuit activity and excitability. We show that DG of mice with more adult-born neurons exhibits decreased strength of neuronal activation and more restricted excitation spread in GCL while maintaining effective output to CA3c. Conversely, blockade of adult hippocampal neurogenesis changed excitability of the DG in the opposite direction. Analysis of GABAergic inhibition onto mature dentate granule neurons in the DG of mice with more adult-born neurons shows a modest readjustment of perisomatic inhibitory synaptic gain without changes in overall inhibitory tone, presynaptic properties or GABAergic innervation pattern. Retroviral labeling of connectivity in mice with more adult-born neurons showed increased number of excitatory synaptic contacts of adult-born neurons onto hilar interneurons. Together, these studies demonstrate that adult hippocampal neurogenesis modifies excitability of mature dentate granule neurons and that this non-cell autonomous effect may be mediated by local circuit mechanisms such as excitatory drive onto hilar interneurons. Modulation of DG excitability by adult-born dentate granule neurons may enhance sparse coding in the GCL to influence pattern separation. PMID:24421758

  20. Enhanced nonlinear interaction in a microcavity under coherent excitation.

    PubMed

    Serna, Samuel; Oden, Jérèmy; Hanna, Marc; Caer, Charles; Le Roux, Xavier; Sauvan, Christophe; Delaye, Philippe; Cassan, Eric; Dubreuil, Nicolas

    2015-11-16

    The large field enhancement that can be achieved in high quality factor and small mode volume photonic crystal microcavities leads to strengthened nonlinear interactions. However, the frequency shift dynamics of the cavity resonance under a pulsed excitation, which is driven by nonlinear refractive index change, tends to limit the coupling efficiency between the pulse and the cavity. As a consequence, the cavity enhancement effect cannot last for the entire pulse duration, limiting the interaction between the pulse and the intra-cavity material. In order to preserve the benefit of light localization throughout the pulsed excitation, we report the first experimental demonstration of coherent excitation of a nonlinear microcavity, leading to an enhanced intra-cavity nonlinear interaction. We investigate the nonlinear behavior of a Silicon-based microcavity subject to tailored positively chirped pulses, enabling to increase the free carrier density generated by two-photon absorption by up to a factor of 2.5 compared with a Fourier-transform limited pulse excitation of equal energy. It is accompanied by an extended frequency blue-shift of the cavity resonance reaching 19 times the linear cavity bandwidth. This experimental result highlights the interest in using coherent excitation to control intra-cavity light-matter interactions and nonlinear dynamics of microcavity-based optical devices. PMID:26698478

  1. [Heart involvement in Anderson-Fabry disease: Italian recommendations for diagnostic, follow-up and therapeutic management].

    PubMed

    Pieruzzi, Federico; Pieroni, Maurizio; Zachara, Elisabetta; Marziliano, Nicola; Morrone, Amelia; Cecchi, Franco

    2015-11-01

    Anderson-Fabry disease is a rare X-linked lysosomal storage disorder caused by mutations of the GLA gene that encodes alpha-galactosidase A. It is characterized by a multisystemic involvement: the renal, neurological, heart, cochleovestibular and cutaneous systems are the most damaged. Morbidity and mortality of Anderson-Fabry disease depend on renal insufficiency, heart failure and nervous system involvement. Left ventricular hypertrophy is the most common cardiac manifestation followed by conduction system disease, valve dysfunction, and arrhythmias. Mild to moderate left ventricular hypertrophy may simulate a non-obstructive hypertrophic cardiomyopathy. Management of Anderson-Fabry disease starting from the diagnosis of cardiac involvement, the prevention of complications, the therapeutic aspects, up to appropriate clinical follow-up, requires a multidisciplinary approach. According to recent management guidelines, only few evidence-based data are available to guide the clinical and therapeutic approach to this rare disease. An Italian Board, composed by nephrologists, cardiologists, geneticists, pediatricians and neurologists has been established in order to approve by consensus a diagnostic and therapeutic management protocol. The authors report the results of this cardiologic management consensus. PMID:26571477

  2. Pattern Formation in Excitable Media

    NASA Astrophysics Data System (ADS)

    Mikhailov, Alexander S.

    1997-03-01

    In this talk I give a short review of the history and the current state of theoretical research on spiral wave patterns in excitable media. I start with the theoretical model of wave propagation in excitable media proposed in 1946 by Wiener and Rosenblueth(N. Wiener and A. Rosenblueth, The mathematical formulation of the problem of conduction of impulses in a network of connected excitable elements, specifically in cardiac muscle, Arch. Inst. Cardiol. Mexico 16 (1946) 205). This model describes spiral waves rotating around obstacles. I show how, by taking additionally into account curvature effects and gradual recovery of the medium after passage of an excitation wave, the model is generalized to describe freely rotating spiral waves and the breakup which produces spirals. In the context of this kinematic model, complex dynamics of spiral waves, i.e. their meandering, drift and resonance, is discussed. Instabilities of spiral waves in confined geometries, i.e. inside a circular region and on a sphere, are analyzed. At the end, I show how spiral waves in such systems can be efficiently controlled by application of a delayed global feedback. The talk is based on the review paper(A. S. Mikhailov, V. A. Davydov, and V. S. Zykov, Complex dynamics of spiral waves and motion of curves, Physica D 70 (1994) 1) and the monograph(A. S. Mikhailov, Foundations of Synergetics I, 2nd revised edition (Springer, Berlin, 1994)).

  3. Elementary Excitations in Quantum Liquids.

    ERIC Educational Resources Information Center

    Pines, David

    1981-01-01

    Discusses elementary excitations and their role in condensed matter physics, focusing on quantum plasma, helium liquids, and superconductors. Considers research primarily conducted in the 1950s and concludes with a brief survey of some closely related further developments. (Author/JN)

  4. High Excitation Gas and ISM

    NASA Technical Reports Server (NTRS)

    Peeters, E.; Martin-Hernandez, N. L.; Rodriguez-Fernandez, N. J.; Tielens, A. G. G. M.

    2004-01-01

    An overview is given of ISO results on regions of high excitation ISM and gas, i.e. HII regions, the Galactic Centre and Supernovae Remnants. IR emission due to fine-structure lines, molecular hydrogen, silicates, polycyclic aromatic hydrocarbons and dust are summarized, their diagnostic capabilities illustrated and their implications highlighted.

  5. Communicating the Excitement of Science

    ScienceCinema

    Michael Turner

    2010-01-08

    In this talk (which will include some exciting science) I will discuss some lessons I have learned about communicating science to scientists (in my own field and others), students, the public, the press, and policy makers in giving 500+ colloquia and seminars, 300+ public lectures and many informal presentations (including cocktail parties).

  6. Launch Excitement with Water Rockets

    ERIC Educational Resources Information Center

    Sanchez, Juan Carlos; Penick, John

    2007-01-01

    Explosions and fires--these are what many students are waiting for in science classes. And when they do occur, students pay attention. While we can't entertain our students with continual mayhem, we can catch their attention and cater to their desires for excitement by saying, "Let's make rockets." In this activity, students make simple, reusable…

  7. Communicating the Excitement of Science

    SciTech Connect

    Michael Turner

    2009-06-05

    In this talk (which will include some exciting science) I will discuss some lessons I have learned about communicating science to scientists (in my own field and others), students, the public, the press, and policy makers in giving 500+ colloquia and seminars, 300+ public lectures and many informal presentations (including cocktail parties).

  8. Actin Automata: Phenomenology and Localizations

    NASA Astrophysics Data System (ADS)

    Adamatzky, Andrew; Mayne, Richard

    Actin is a globular protein which forms long filaments in the eukaryotic cytoskeleton, whose roles in cell function include structural support, contractile activity to intracellular signaling. We model actin filaments as two chains of one-dimensional binary-state semi-totalistic automaton arrays to describe hypothetical signaling events therein. Each node of the actin automaton takes state "0" (resting) or "1" (excited) and updates its state in discrete time depending on its neighbor's states. We analyze the complete rule space of actin automata using integral characteristics of space-time configurations generated by these rules and compute state transition rules that support traveling and mobile localizations. Approaches towards selection of the localization supporting rules using the global characteristics are outlined. We find that some properties of actin automata rules may be predicted using Shannon entropy, activity and incoherence of excitation between the polymer chains. We also show that it is possible to infer whether a given rule supports traveling or stationary localizations by looking at ratios of excited neighbors that are essential for generations of the localizations. We conclude by applying biomolecular hypotheses to this model and discuss the significance of our findings in context with cell signaling and emergent behavior in cellular computation.

  9. Spontaneous excitation of atoms near a phase-conjugating mirror

    SciTech Connect

    Cook, R.J.; Milonni, P.W.

    1988-07-01

    The authors show by means of a semiclassical theory that the ground state of a localized collection of two-level atoms is unstable when the atomic sample is sufficiently close to a phase-conjugating mirror with high gain. Any small disturbance causes the atoms to become excited and begin fluorescing, the fluorescence taking the form of a sequence of superradiant pulses. Experiments to test this prediction seem possible.

  10. Electron acceleration by parametrically excited Langmuir waves. [in ionospheric modification

    NASA Technical Reports Server (NTRS)

    Fejer, J. A.; Graham, K. N.

    1974-01-01

    Simple physical arguments are used to estimate the downward-going energetic electron flux due to parametrically excited Langmuir waves in ionospheric modification experiments. The acceleration mechanism is a single velocity reversal as seen in the frame of the Langmuir wave. The flux is sufficient to produce the observed ionospheric airglow if focusing-type instabilities are invoked to produce moderate local enhancements of the pump field.

  11. Validation of the Lower-Risk MD Anderson Prognostic Scoring System for Patients With Myelodysplastic Syndrome.

    PubMed

    Komrokji, Rami; Ramadan, Hanadi; Al Ali, Najla; Corrales-Yepez, Maria; Zhang, Ling; Padron, Eric; Lancet, Jeffrey; List, Alan

    2015-06-01

    The International Prognostic Scoring System (IPSS) is the most widely used tool for risk assessment and treatment decisions for myelodysplastic syndrome (MDS). Several new models have been proposed to identify a subset of lower-risk patients with MDS who are experiencing inferior than expected outcomes. We validated the Lower-Risk MD Anderson Risk Model (LR-MDAS) in 1288 lower-risk patients with MDS by the IPSS. On the basis of the LR-MDAS, 228 patients (17%) were in category 1, 730 patients (57%) were in category 2, 315 patients (25%) were in category 3, and 15 patients (1%) were in an unknown category. The median overall survival for the corresponding LR-MDAS categories was (1) 109 months (95% confidence interval [CI], 82-137), (2) 56 months (95% CI, 58-73), and (3) 29 months (95% CI, 24-35) (P < .005). Overall, 25% of patients were upstaged to category 3. LR-MDAS refined prognostic value among very low-, low-, and intermediate-risk Revised IPSS. The rate of acute myeloid leukemia transformation according to LR-MDAS was 15%, 18%, and 29% for categories 1, 2, and 3, respectively (P < .005). Our data validate the prognostic value of the LR-MDAS model, but the utility of it as a treatment decision tool should be studied prospectively. PMID:26297280

  12. An inventory of wetlands in the East Fork Poplar Creek floodplain, Anderson and Roane Counties, Tennessee

    SciTech Connect

    1992-12-01

    An inventory of wetlands within the floodplain of East Fork Poplar Creek (EFPC) in Anderson and Roane Counties, Tennessee was conducted during October, 1991 through May, 1992 for the US Department of Energy (DOE) by the US Army Corps of Engineers, Nashville District. About 15 miles of EFPC channel and 500 acres of its floodplain are contaminated with mercury and other contaminants released from the Y-12 Plant on the DOE Oak Ridge Reservation. The wetland inventory will serve as baseline information for DOE`s remedial action planning and National Environmental Policy Act compliance efforts related to the contamination. In order to provide broad wetland determinations beyond which future wetland definitions are unlikely to expand, the 1989 Federal Manual for Identifying And Delineating Jurisdictional Wetlands was utilized. Using the manual`s methodology in a contaminated system under the approved health and safety plan presented some unique problems, resulting in intrusive sampling for field indicators of hydric soils being accomplished separately from observation of other criteria. Beginning with wetland areas identified on National Wetland Inventory Maps, the entire floodplain was examined for presence of wetland criteria, and 17 wetlands were identified ranging from 0.01 to 2.81 acres in size. The majority of wetlands identified were sized under 1 acre. Some of the wetlands identified were not delineated on the National Wetland Inventory Maps, and much of the wetland area delineated on the maps did not meet the criteria under the 1989 manual.

  13. Ultrastructural study of renal involvement in two females with Anderson-Fabry disease.

    PubMed

    Tosoni, A; Nebuloni, M; Zerbi, P; Vago, L; Comotti, C; Sessa, A

    2005-01-01

    Anderson-Fabry disease (AFD) is a rare X-linked lipid storage disorder due to a deficient lysosomal a-galactosidase A (a-Gal) activity. In males with the classic form of the disease the enzymatic defect leads to progressive accumulation of glycosphingolipids (GL) in different organs, mainly in the kidney, heart, and brain, causing severe multisystem failure. AFD is usually mild in heterozygous females, but severe cerebrovascular, renal, and cardiac manifestations have been rarely described. The aim of this study is to describe renal involvement of mild symptomatic female carriers by ultrastructural analysis focusing to microvascular lesions, considered to be one of the major causes of systemic disease in AFD. Resin-embedded renal biopsies from 2 sisters with isolated mild proteinuria and belonging to a family group with AFD were observed by light and electron microscopy. In spite of the mild clinical symptoms, diffuse GL storages were demonstrated in all types of glomerular cells and in interstitial endothelial cells. Moreover, platelets were frequently observed in glomerular vassels, a feature coherent with a possible role of prothrombotic state, and platelet activation, in early glomerular lesions. PMID:16036875

  14. Advanced Anderson-Fabry disease presenting with left ventricular apical aneurysm and ventricular tachycardia

    PubMed Central

    Poulin, Marie-France; Shah, Alap; Trohman, Richard G; Madias, Christopher

    2015-01-01

    A 54-year-old female with Anderson-Fabry disease (AFD)-R342Q missense mutation on exon 7 in alpha-galactosidase A (GLA) gene - presented with sustained ventricular tachycardia. Imaging confirmed the presence of a new left ventricular apical aneurysm (LVAA) and a significantly reduced intra-cavitary gradient compared to two years prior. AFDcv is an X-linked lysosomal storage disorder caused by GLA enzyme deficiency. The phenotypic expression of AFD in the heart is not well described. Cardiac involvement can include left ventricular hypertrophy (LVH), which is typically symmetric, but can also mimic hypertrophic cardiomyopathy (HCM). Left ventricular apical aneurysm is a rare finding in HCM. We suggest a shared mechanism of LVAA formation in AFD and HCM, independent of the underlying cardiomyopathy. Mechanisms of LVAA formation in HCM include genetic predisposition and long-standing left ventricular wall stress from elevated intra-cavitary systolic pressures due to mid-cavitary obstruction. Both mechanisms are supported in this patient (a brother with AFD also developed a small LVAA). Screening for AFD should be considered in cases of unexplained LVH, particularly in patients with the aneurysmal variant of HCM. PMID:26090373

  15. Suitability of Palestine salt dome, Anderson Co. , Texas for disposal of high-level radioactive waste

    SciTech Connect

    Patchick, P.F.

    1980-01-01

    The suitability of Palestine salt dome, in Anderson County, Texas, is in serious doubt for a repository to isolate high-level nuclear waste because of abandoned salt brining operations. The random geographic and spatial occurrence of 15 collapse sinks over the dome may prevent safe construction of the necessary surface installations for a repository. The dissolution of salt between the caprock and dome, from at least 15 brine wells up to 500 feet deep, may permit increased rates of salt dissolution long into future geologic time. The subsurface dissolution is occurring at a rate difficult, if not impossible, to assess or to calculate. It cannot be shown that this dissolution rate is insignificant to the integrity of a future repository or to ancillary features. The most recent significant collapse was 36 feet in diameter and took place in 1972. The other collapses ranged from 27 to 105 feet in diameter and from 1.5 to more than 15 feet in depth. ONWI recommends that this dome be removed from consideration as a candidate site.

  16. Phase diagram and reentrance for the 3D Edwards-Anderson model using information theory

    NASA Astrophysics Data System (ADS)

    Cortez, V.; Saravia, G.; Vogel, E. E.

    2014-12-01

    Data compressor techniques are used to study the phase diagram of the generalized Edwards-Anderson model in three dimensions covering the full range of mixture between ferromagnetic (concentration 1-x) and antiferromagnetic interactions (concentration x). The recently proposed data compressor wlzip is used to recognize criticality by the maximum information content in the files storing the simulation processes. The method allows not only the characterization of the ferromagnetic to paramagnetic (FP) transition (x<0.22, or x>0.78) but also it equally well yields the spin-glass to paramagnetic (SP) transition (0.22

  17. Transverse localization of light in nonlinear photonic lattices with dimensionality crossover

    SciTech Connect

    Jovic, Dragana M.; Belic, Milivoj R.; Denz, Cornelia

    2011-10-15

    In a numerical study, we demonstrate the dimensionality crossover in Anderson localization of light. We consider crossover from the two-dimensional (2D) to the one-dimensional (1D) lattice, optically induced in both linear and nonlinear dielectric media. The joint influence of nonlinearity and disorder on Anderson localization in such systems is discussed in some detail. We find that, in the linear regime, the localization is more pronounced in two dimensions than in one dimension. We also find that the localization in the intermediate cases of crossover is less pronounced than in both the pure 1D and 2D cases in the linear regime, whereas in the nonlinear regime this depends on the strength of the nonlinearity. There exist strongly nonlinear regimes in which 1D localization is more pronounced than the 2D localization, opposite to the case of the linear regime. We find that the dimensionality crossover is characterized by two different localization lengths, whose behavior is different along different transverse directions.

  18. Diffusion and excitation transfer of excited alkali-metal atoms

    NASA Astrophysics Data System (ADS)

    Bouledroua, M.; Dalgarno, A.; Côté, R.

    2002-01-01

    We report calculations of diffusion, excitation transfer, width, and shift cross sections. We use these cross sections to obtain the diffusion coefficient and the width and line shift due to collisions of alkali-metal atoms in the impact approximation. The results are compared to analytical expressions obtained from semiclassical treatments, and with measured widths for sodium atoms. Extension to other alkali metal atoms is also given.

  19. Phonon localization drives polar nanoregions in a relaxor ferroelectric

    NASA Astrophysics Data System (ADS)

    Manley, M. E.; Lynn, J. W.; Abernathy, D. L.; Specht, E. D.; Delaire, O.; Bishop, A. R.; Sahul, R.; Budai, J. D.

    2014-04-01

    Relaxor ferroelectrics exemplify a class of functional materials where interplay between disorder and phase instability results in inhomogeneous nanoregions. Although known for about 30 years, there is no definitive explanation for polar nanoregions (PNRs). Here we show that ferroelectric phonon localization drives PNRs in relaxor ferroelectric PMN-30%PT using neutron scattering. At the frequency of a preexisting resonance mode, nanoregions of standing ferroelectric phonons develop with a coherence length equal to one wavelength and the PNR size. Anderson localization of ferroelectric phonons by resonance modes explains our observations and, with nonlinear slowing, the PNRs and relaxor properties. Phonon localization at additional resonances near the zone edges explains competing antiferroelectric distortions known to occur at the zone edges. Our results indicate the size and shape of PNRs that are not dictated by complex structural details, as commonly assumed, but by phonon resonance wave vectors. This discovery could guide the design of next generation relaxor ferroelectrics.

  20. Excitation mechanisms of Er optical centers in GaN epilayers

    NASA Astrophysics Data System (ADS)

    George, D. K.; Hawkins, M. D.; McLaren, M.; Jiang, H. X.; Lin, J. Y.; Zavada, J. M.; Vinh, N. Q.

    2015-10-01

    We report direct evidence of two mechanisms responsible for the excitation of optically active Er3+ ions in GaN epilayers grown by metal-organic chemical vapor deposition. These mechanisms, resonant excitation via the higher-lying inner 4f shell transitions and band-to-band excitation of the semiconductor host, lead to narrow emission lines from isolated and the defect-related Er optical centers. However, these centers have different photoluminescence spectra, local defect environments, decay dynamics, and excitation cross sections. The photoluminescence at 1.54 ?m from the isolated Er optical center which can be excited by either mechanism has the same decay dynamics, but possesses a much higher excitation cross-section under band-to-band excitation. In contrast, the photoluminescence at 1.54 ?m from the defect-related Er optical center can only be observed through band-to-band excitation but has the largest excitation cross-section. These results explain the difficulty in achieving gain in Er doped GaN and indicate approaches for realization of optical amplification, and possibly lasing, at room temperature.

  1. Local constants of motion imply information propagation

    NASA Astrophysics Data System (ADS)

    Friesdorf, M.; Werner, A. H.; Goihl, M.; Eisert, J.; Brown, W.

    2015-11-01

    Interacting quantum many-body systems are expected to thermalize, in the sense that the evolution of local expectation values approaches a stationary value resembling a thermal ensemble. This intuition is notably contradicted in systems exhibiting many-body localisation (MBL). In stark contrast to the non-interacting case of Anderson localisation, the entanglement of states grows without limit over time, albeit slowly. In this work, we establish a novel link between quantum information theory and notions of condensed matter physics, capturing this phenomenon in the Heisenberg picture. We show that the mere existence of local constants of motion, often taken as the defining property of MBL, together with a generic spectrum of the Hamiltonian, is already sufficient to rigorously prove information propagation: these systems can be used to send a classical bit over arbitrary distances, in that the impact of a local perturbation can be detected arbitrarily far away. This counterintuitive result is compatible with and further corroborates the intuition of a slow entanglement growth following global quenches in MBL systems. We perform a detailed perturbation analysis of quasi-local constants of motion and also show that they indeed can be used to construct efficient spectral tensor networks, as recently suggested. Our results provide a detailed and at the same time model-independent picture of information propagation in MBL systems.

  2. Autoresonant excitation of dark solitons.

    PubMed

    Borich, M A; Shagalov, A G; Friedland, L

    2015-01-01

    Continuouslyphase-locked (autoresonant) dark solitons of the defocusing nonlinear Schrodinger equation are excited and controlled by driving the system by a slowly chirped wavelike perturbation. The theory of these excitations is developed using Whitham's averaged variational principle and compared with numerical simulations. The problem of the threshold for transition to autoresonance in the driven system is studied in detail, focusing on the regime when the weakly nonlinear frequency shift in the problem differs from the typical quadratic dependence on the wave amplitude. The numerical simulations in this regime show a deviation of the autoresonance threshold on the driving amplitude from the usual 3/4 power dependence on the driving frequency chirp rate. The theory of this effect is suggested. PMID:25679688

  3. Tachyonic thermal excitations and causality

    E-print Network

    Ernst Trojan; George V. Vlasov

    2011-10-08

    We consider an ideal Fermi gas of tachyonic thermal excitations as a continuous medium and establish when it satisfies the causality condition. At high temperature the sound speed is always subluminal $c_stachyon matter below the critical temperature $T_ctachyon mass $m$. The pressure $P$ and energy density $E$ cannot be arbitrary small, but $P$ can exceed $E$, and $P=2.36E$ when $T\\rightarrow T_c$.

  4. Oscillator response to nonstationary excitation

    NASA Technical Reports Server (NTRS)

    Spanos, P.-T. D.; Solomos, G. P.

    1984-01-01

    Analytical solutions are presented regarding probability density distributions of various response parameters of a lightly damped oscillator. The oscillator is subjected to a broad-band stochastic excitation which possesses a time-variant power spectrum. The analytical solutions are derived by utilizing appropriate Fokker-Planck equations which govern Markovian approximations of the response parameters considered. The reliability of the approximate analytical solution is tested by using pertinent data generated by a digital Monte Carlo study.

  5. Wedding ring shaped excitation coil

    DOEpatents

    MacLennan, Donald A. (Gaithersburg, MD); Tsai, Peter (Olney, MD)

    2001-01-01

    A high frequency inductively coupled electrodeless lamp includes an excitation coil with an effective electrical length which is less than one half wavelength of a driving frequency applied thereto, preferably much less. The driving frequency may be greater than 100 MHz and is preferably as high as 915 MHz. Preferably, the excitation coil is configured as a non-helical, semi-cylindrical conductive surface having less than one turn, in the general shape of a wedding ring. At high frequencies, the current in the coil forms two loops which are spaced apart and parallel to each other. Configured appropriately, the coil approximates a Helmholtz configuration. The lamp preferably utilizes an bulb encased in a reflective ceramic cup with a pre-formed aperture defined therethrough. The ceramic cup may include structural features to aid in alignment and/or a flanged face to aid in thermal management. The lamp head is preferably an integrated lamp head comprising a metal matrix composite surrounding an insulating ceramic with the excitation integrally formed on the ceramic. A novel solid-state oscillator preferably provides RF power to the lamp. The oscillator is a single active element device capable of providing over 70 watts of power at over 70% efficiency.

  6. Vibrationally excited hydroxyl tagging velocimetry.

    PubMed

    Grady, Nathan; Pitz, Robert W

    2014-11-01

    A new molecular-based velocity method is developed for high-temperature flame gases based on the hydroxyl tagging velocimetry (HTV) technique. In vibrationally excited HTV (VE-HTV), two photons from a KrF laser (248 nm) dissociate H2O into a tag line of vibrationally excited OH (v=1). The excited state OH tag is selectively detected in a background of naturally occurring ground state OH (v=0). In atmospheric pressure laboratory burners, the OH (v=1) tag persists for 5-10 ?s, allowing single-shot velocity measurements along a 2 cm line under lean, stoichiometric, and rich flame conditions with temperatures reaching 2300 K. Mean velocity measurements are demonstrated in a lean (?=0.78) premixed H2/air turbulent flame (Re=26,550) laboratory flame. The VE-HTV method is best suited to measure high-speed velocities in hot combustion environments in the presence of background OH. PMID:25402874

  7. Phonon-polariton excitations in photonic crystals Kerwyn Casey Huang,* Peter Bienstman, John. D. Joannopoulos, and Keith A. Nelson

    E-print Network

    Fan, Shanhui

    Phonon-polariton excitations in photonic crystals Kerwyn Casey Huang,* Peter Bienstman, John. D The incorporation of materials which exhibit transverse phonon-polariton excitations into a photonic crystal localization in the polaritonic material and metalliclike bands with complete flux expulsion in an extremely

  8. Cooperative behavior between oscillatory and excitable units: the peculiar role of positive coupling-frequency correlations

    E-print Network

    Bernard Sonnenschein; Thomas K. DM. Peron; Francisco A. Rodrigues; Jürgen Kurths; Lutz Schimansky-Geier

    2014-08-15

    We study the collective dynamics of noise-driven excitable elements, so-called active rotators. Crucially here, the natural frequencies and the individual coupling strengths are drawn from some joint probability distribution. Combining a mean-field treatment with a Gaussian approximation allows us to find examples where the infinite-dimensional system is reduced to a few ordinary differential equations. Our focus lies in the cooperative behavior in a population consisting of two parts, where one is composed of excitable elements, while the other one contains only self-oscillatory units. Surprisingly, excitable behavior in the whole system sets in only if the excitable elements have a smaller coupling strength than the self-oscillating units. In this way positive local correlations between natural frequencies and couplings shape the global behavior of mixed populations of excitable and oscillatory elements.

  9. DE-1 and COSMOS 1809 observations of lower hybrid waves excited by VLF whistler mode waves

    NASA Technical Reports Server (NTRS)

    Bell, T. F; Inan, U. S.; Lauben, D.; Sonwalkar, V. S.; Helliwell, R. A.; Sobolev, Ya. P.; Chmyrev, V. M.; Gonzalez, S.

    1994-01-01

    Past work demostrates that strong lower hybrid (LH) waves can be excited by electromagnetic whistler mode waves throughout large regions of the topside ionosphere and magnetosphere. The effects of the excited LH waves upon the suprathermal ion population in the topside ionosphere and magnetosphere depend upon the distribution of LH wave amplitude with wavelength lambda. The present work reports plasma wave data from the DE-1 and COSMOS 1809 spacecraft which suggests that the excited LH wave spectrum has components for which lambda less than or equal to 3.5 m when excitation occurs at a frequency roughly equal to the local lower hybrid resonance frequency. This wavelength limit is a factor of approximately 3 below that reported in past work and suggests that the excited LH waves can interact with suprathermal H(+) ions with energy less than or equal to 6 eV. This finding supports recent work concerning the heating of suprathermal ions above thunderstorm cells.

  10. Resource Paper: Molecular Excited State Relaxation Processes.

    ERIC Educational Resources Information Center

    Rhodes, William

    1979-01-01

    Develops the concept of oscillatory v dissipative limits as it applies to electronic excited state processes in molecular systems. Main emphasis is placed on the radiative and nonradiative dynamics of the excited state of a molecule prepared by interaction with light or some other excitation source. (BT)

  11. On Planetary Evolution and the Evolution of Planetary Science During the Career of Don Anderson

    NASA Astrophysics Data System (ADS)

    Solomon, S. C.

    2003-12-01

    The planets of our solar system have long been viewed by Don Anderson as laboratories for testing general aspects of planetary evolution and as points of comparison to the Earth. I was fortunate to have been a student 39 years ago in a course at Caltech that Don taught with Bob Kovach on the interiors of the Earth and the planets. At that time, Mariner 4 had not yet flown by Mars, the lunar Ranger program was still in progress, and it was permissible to entertain the hypothesis that all of the terrestrial planets were identical in bulk composition. In the last four decades spacecraft have visited every planet from Mercury to Neptune; samples from the Moon, Mars, asteroids, and comets reside in our laboratories; and more than 100 planets have been discovered orbiting other stars. More importantly, traditionally distinct fields have merged to the point where planetary scientists must be conversant with the findings and modes of thinking from astronomy and biology as well as the geosciences. A few examples illustrate this confluence. Theoretical models for the structure of the atmospheres of gas-giant planets led to the first astronomical detection of an extrasolar planetary atmosphere for the transiting planet HD209458b. Although the atmospheric models were based on those for solar-system gas giants, the 3.5-day orbital period means that this planet is 100 times closer to its star than Jupiter is to the Sun, its effective temperature is 1100 K, and the detected signature of the planetary atmosphere was absorption by neutral sodium. Sodium in Mercury's exosphere, detected astronomically from Earth, figures into the question of how the terrestrial planets came to have distinct bulk compositions. Hypotheses to account for Mercury's high uncompressed density, and by inference its high ratio of metal to silicate, range from chemical gradients in the early solar nebula to preferential removal of silicates from a differentiated protoplanet by nebular heating or giant impact disruption, processes that would have affected the final composition of the other inner planets to lesser degrees. These hypotheses will be distinguishable by future remote sensing measurements from a spacecraft in Mercury orbit, but all lead to the prediction that volatile species such as sodium should be deficient in Mercury's silicate fraction. The most recent models for Mercury's exosphere are consistent with the idea that the required fresh supply of sodium from Mercury's surface is no greater than that predicted for meteorite infall. One of the leading questions driving the current exploration of Mars is whether the surface or subsurface was ever conducive to the origin and evolution of life. Sites of hydrothermal circulation within the crust may have provided the necessary energy and chemical building blocks. Remote sensing of candidate hydrothermal minerals at the Martian surface is the leading technique being used to seek such sites, but paleomagnetism may offer another route. Several hypotheses link hydrothermal activity to either the formation of magnetic carriers during the lifetime of the Martian dynamo or the alteration of such carriers after the dynamo ceased, leading to the possibility that high-resolution mapping of crustal magnetism may provide a prospecting tool for promising Martian biological habitats. As Don Anderson showed us by example throughout his career, students of the Earth need not confine their attention to a single planet or even a single planetary system. The lessons from diverse fields that planetary scientists must master to stay current will keep all of us --- like Don --- young and curious.

  12. Chronic renal failure, dialysis, and renal transplantation in Anderson-Fabry disease.

    PubMed

    Sessa, Adalberto; Meroni, Mietta; Battini, Graziana; Righetti, Marco; Mignani, Renzo

    2004-09-01

    Anderson-Fabry disease (AFd) is a rare, inherited, x-linked disease characterized by the deficiency of the lysosomal enzymatic alpha-galactosidase A activity (alpha-Gal-A). The enzyme defect leads to progressive accumulation of glycosphingolipids (GL) in all kinds of cells, tissues, organs, and body fluids. The clinical manifestations are very protean, the residual activity of alpha-Gal-A and/or different gene mutations might explain different phenotypes, but as yet these concepts have not been proven. Usually, patients with AFd show 3 clinical phases, more evident in men than in heterozygous women. The first phase (childhood and adolescence) is characterized by myalgia, arthralgia, acroparesthesia, fever, cutaneous angiokeratomas, and corneal opacities. The second phase is characterized mainly by renal involvement. In the third phase, severe renal impairment and involvement of cerebrovascular and cardiovascular systems are present. The progression to end-stage renal disease (ESRD) is common in hemizygous males (3rd-5th decade of life); usually, death occurs because of cerebral and/or cardiovascular complications in patients undergoing chronic dialysis therapies. The survival of patients with AFd in dialysis is better than in diabetic patients, but it clearly is decreased compared with uremic patients with other nephropathies, despite a lower mean age of uremia (50 versus 60 y). The outcome of kidney transplantation is similar to that found in other patients with ESRD, despite controversial issues published in the past. The use of a kidney donor with normal alpha-Gal-A activity in the control of the metabolic systemic disease is unproven. The recurrence of GL deposits in the kidney graft has been documented rarely. The definitive treatment for AFd is enzyme replacement therapy with purified alpha-Gal-A produced by a genetically engineered human cell line or Chinese hamster oocytes: relatively short-term studies have shown a significant treatment effect on clinical outcome measures. PMID:15490423

  13. Gutzwiller wave-function solution for Anderson lattice model: Emerging universal regimes of heavy quasiparticle states

    NASA Astrophysics Data System (ADS)

    Wysoki?ski, Marcin M.; Kaczmarczyk, Jan; Spa?ek, Jozef

    2015-09-01

    The recently proposed diagrammatic expansion (DE) technique for the full Gutzwiller wave function (GWF) is applied to the Anderson lattice model. This approach allows for a systematic evaluation of the expectation values with full Gutzwiller wave function in finite-dimensional systems. It introduces results extending in an essential manner those obtained by means of the standard Gutzwiller approximation (GA), which is variationally exact only in infinite dimensions. Within the DE-GWF approach we discuss the principal paramagnetic properties and their relevance to heavy-fermion systems. We demonstrate the formation of an effective, narrow f band originating from atomic f -electron states and subsequently interpret this behavior as a direct itineracy of f electrons; it represents a combined effect of both the hybridization and the correlations induced by the Coulomb repulsive interaction. Such a feature is absent on the level of GA, which is equivalent to the zeroth order of our expansion. Formation of the hybridization- and electron-concentration-dependent narrow f band rationalizes the common assumption of such dispersion of f levels in the phenomenological modeling of the band structure of CeCoIn5. Moreover, it is shown that the emerging f -electron direct itineracy leads in a natural manner to three physically distinct regimes within a single model that are frequently discussed for 4 f - or 5 f -electron compounds as separate model situations. We identify these regimes as (i) the mixed-valence regime, (ii) Kondo/almost-Kondo insulating regime, and (iii) the Kondo-lattice limit when the f -electron occupancy is very close to the f -state half filling, ?1 . The nonstandard features of the emerging correlated quantum liquid state are stressed.

  14. Non-equilibrium STLS approach to transport properties of single impurity Anderson model

    SciTech Connect

    Rezai, Raheleh Ebrahimi, Farshad

    2014-04-15

    In this work, using the non-equilibrium Keldysh formalism, we study the effects of the electron–electron interaction and the electron-spin correlation on the non-equilibrium Kondo effect and the transport properties of the symmetric single impurity Anderson model (SIAM) at zero temperature by generalizing the self-consistent method of Singwi, Tosi, Land, and Sjolander (STLS) for a single-band tight-binding model with Hubbard type interaction to out of equilibrium steady-states. We at first determine in a self-consistent manner the non-equilibrium spin correlation function, the effective Hubbard interaction, and the double-occupancy at the impurity site. Then, using the non-equilibrium STLS spin polarization function in the non-equilibrium formalism of the iterative perturbation theory (IPT) of Yosida and Yamada, and Horvatic and Zlatic, we compute the spectral density, the current–voltage characteristics and the differential conductance as functions of the applied bias and the strength of on-site Hubbard interaction. We compare our spectral densities at zero bias with the results of numerical renormalization group (NRG) and depict the effects of the electron–electron interaction and electron-spin correlation at the impurity site on the aforementioned properties by comparing our numerical result with the order U{sup 2} IPT. Finally, we show that the obtained numerical results on the differential conductance have a quadratic universal scaling behavior and the resulting Kondo temperature shows an exponential behavior. -- Highlights: •We introduce for the first time the non-equilibrium method of STLS for Hubbard type models. •We determine the transport properties of SIAM using the non-equilibrium STLS method. •We compare our results with order-U2 IPT and NRG. •We show that non-equilibrium STLS, contrary to the GW and self-consistent RPA, produces the two Hubbard peaks in DOS. •We show that the method keeps the universal scaling behavior and correct exponential behavior of Kondo temperature.

  15. The University of Texas M.D. Anderson Cancer Center Proton Therapy Facility

    SciTech Connect

    Smith, Alfred; Newhauser, Wayne; Latinkic, Mitchell; Hay, Amy; Cox, James; McMaken, Bruce; Styles, John

    2003-08-26

    The University of Texas M.D. Anderson Cancer Center (MDACC), in partnership with Sanders Morris Harris Inc., a Texas-based investment banking firm, and The Styles Company, a developer and manager of hospitals and healthcare facilities, is building a proton therapy facility near the MDACC main complex at the Texas Medical Center in Houston, Texas USA. The MDACC Proton Therapy Center will be a freestanding, investor-owned radiation oncology center offering state-of-the-art proton beam therapy. The facility will have four treatment rooms: three rooms will have rotating, isocentric gantries and the fourth treatment room will have capabilities for both large and small field (e.g. ocular melanoma) treatments using horizontal beam lines. There will be an additional horizontal beam room dedicated to physics research and development, radiation biology research, and outside users who wish to conduct experiments using proton beams. The first two gantries will each be initially equipped with a passive scattering nozzle while the third gantry will have a magnetically swept pencil beam scanning nozzle. The latter will include enhancements to the treatment control system that will allow for the delivery of proton intensity modulation treatments. The proton accelerator will be a 250 MeV zero-gradient synchrotron with a slow extraction system. The facility is expected to open for patient treatments in the autumn of 2005. It is anticipated that 675 patients will be treated during the first full year of operation, while full capacity, reached in the fifth year of operation, will be approximately 3,400 patients per year. Treatments will be given up to 2-shifts per day and 6 days per week.

  16. The role of localization in glasses and supercooled liquids

    E-print Network

    Bembenek, Scott D.; Laird, Brian Bostian

    1996-01-01

    Localized excitations (tunneling modes, soft harmonic vibrations) are believed to play a dominant role in the thermodynamics and transport properties of glasses at low temperature. Using instantaneous normal?mode (INM) analysis, we explore the role...

  17. Excitability of guided waves in composites with PWAS transducers

    NASA Astrophysics Data System (ADS)

    Shen, Yanfeng; Giurgiutiu, Victor

    2015-03-01

    Piezoelectric Wafer Active Sensors (PWAS) are convenient enablers for generating and receiving ultrasonic guided waves. The wide application of composite structures has put new challenges for the Structural Health Monitoring (SHM) and Nondestructive Evaluation (NDE) community due to the general anisotropic behaviors and complicated guided wave features in composites. The excitability of guided waves in composite structures directly influences the implementation of active sensing systems to achieve the best interrogation of certain sensing directions. This paper presents a hybrid modeling technique for studying the excitably of guided waves in composite structures with PWAS transducers. This hybrid technique comprehensively covers local finite element model (FEM), semi-analytical finite element (SAFE) method, and analytical guided wave solutions. Harmonic analysis of a small-size local FEM with non-reflective boundaries (NRB) was carried out for obtaining guided wave generation features in plate structures. The PWAS transducers were modeled with coupled filed elements. Thus, the FEM can fully capture the geometry and material property effects of PWAS transducers and their influence on the guided wave excitation. SAFE method was used to obtain the complicated guided wave features in composites such as dispersion curves and modeshapes. The SAFE procedure was coded into MATLAB Graphical User Interface (GUI), and the software SAFE-DISPERSION was developed. To study the excitability of each wave mode, we considered all the possible wave modes being generated simultaneously and propagating independently. The analytical wave expressions based on the exact guided wave solution with Hankel functions were used to join the SAFE method and the local FEM. Formulated in frequency domain, the hybrid model is highly efficient, providing an over determined equation system for the calculation of mode participation factors. Case studies were carried out: (1) the Lamb wave excitability in an aluminum plate was investigated and compared with classical pin force models to show the feasibility of the hybrid technique; (2) the guided wave excitability in a woven glass fiber composite (GFRP) plate was studied with circular and square PWAS transducers. The paper finishes with summary, conclusions, and suggestions for future work.

  18. Speech synthesis by glottal excited linear prediction.

    PubMed

    Childers, D G; Hu, H T

    1994-10-01

    This paper describes a linear predictive (LP) speech synthesis procedure that resynthesizes speech using a 6th-order polynomial waveform to model the glottal excitation. The coefficients of the polynomial model form a vector that represents the glottal excitation waveform for one pitch period. A glottal excitation code book with 32 entries for voiced excitation is designed and trained using two sentences spoken by different speakers. The purpose for using this approach is to demonstrate that quantization of the glottal excitation waveform does not significantly degrade the quality of speech synthesized with a glottal excitation linear predictive (GELP) synthesizer. This implementation of the LP synthesizer is patterned after both a pitch-excited LP speech synthesizer and a code excited linear predictive (CELP) speech coder. In addition to the glottal excitation codebook, we use a stochastic codebook with 256 entries for unvoiced noise excitation. Analysis techniques are described for constructing both codebooks. The GELP synthesizer, which resynthesizes speech with high quality, provides the speech scientist a simple speech synthesis procedure that uses established analysis techniques, that is able to reproduce all speed sounds, and yet also has an excitation model waveform that is related to the derivative of the glottal flow and the integral of the residue. It is conjectured that the glottal excitation codebook approach could provide a mechanism for quantitatively comparing the differences in glottal excitation codebooks for male and female speakers and for speakers with vocal disorders and for speakers with different voice types such as breathy and vocal fry voices. Conceivably, one could also convert the voice of a speaker with one voice type, e.g., breathy, to the voice of a speaker with another voice type, e.g., vocal fry, by synthesizing speech using the vocal tract LP parameters for the speaker with the breathy voice excited by the glottal excitation codebook trained for vocal fry. PMID:7963019

  19. Peculiarities of collisional excitation transfer with excited screened energy levels of atoms

    SciTech Connect

    Gerasimov, V. A.; Gerasimov, V. V.; Pavlinskiy, A. V.

    2007-09-15

    We report an experimental discovery of deviations from the known regularities in collisional excitation transfer processes for metal atoms. The collisional excitation transfer with excited screened energy levels of thulium and dysprosium atoms is studied. The selecting role of the screening 6s shell in collisional excitation transfer is shown.

  20. Surface plasmon polariton excitation by second harmonic generation in single organic nanofibers.

    PubMed

    Simesen, Paw; Søndergaard, Thomas; Skovsen, Esben; Fiutowski, Jacek; Rubahn, Horst-Günter; Bozhevolnyi, Sergey I; Pedersen, Kjeld

    2015-06-15

    Coherent local excitation of surface plasmon polaritons (SPPs) by second-harmonic generation (SHG) in individual aligned crystalline organic functionalized para-phenylene nanofibers deposited on a thin silver film is demonstrated. The SH-SPP generation is considered theoretically and investigated experimentally with angular-resolved leakage radiation spectroscopy for normal incidence of the excitation beam. Both measurements and simulations show asymmetric excitation of left- and right-propagating SH-SPPs, which is explained as an effect of fiber molecules being oriented at an angle relative to the silver film surface. PMID:26193608