NASA Astrophysics Data System (ADS)
Xu, T.; Krems, R. V.
2015-06-01
We consider the dynamics of rotational excitations placed on a single molecule in spatially disordered one-dimensional (1D), two-dimensional (2D) and three-dimensional (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? 1 s. 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.
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.
Anderson Localization and Supersymmetry
NASA Astrophysics Data System (ADS)
Efetov, K. B.
The supersymmetry method for study of disordered systems is shortly reviewed. The discussion starts with a historical introduction followed by an explanation of the idea of using Grassmann anticommuting variables for investigating disordered metals. After that the nonlinear supermatrix ?-model is derived. Solution of several problems obtained with the help of the ?-model is presented. This includes the problem of the level statistics in small metal grains, localization in wires and films, and Anderson metal-insulator transition. Calculational schemes developed for studying these problems form the basis of subsequent applications of the supersymmetry approach.
Probing statistical properties of Anderson localization with quantum emitters
Stephan Smolka; Henri Thyrrestrup; Luca Sapienza; Tau B. Lehmann; Kristian R. Rix; Luis S. Froufe-Pérez; Pedro D. García; Peter Lodahl
2011-03-30
Wave propagation in disordered media can be strongly modified by multiple scattering and wave interference. Ultimately the so-called Anderson-localized regime is reached when the waves become strongly confined in space. So far, Anderson localization of light has been probed in transmission experiments by measuring the intensity of an external light source after propagation through a disordered medium. However, discriminating between Anderson localization and losses in these experiments remains a major challenge. Here we present an alternative approach where we use quantum emitters embedded in disordered photonic crystal waveguides as light sources. Anderson-localized modes are efficiently excited and the analysis of the photoluminescence spectra allows to explore their statistical properties paving a way for controlling Anderson localization in disordered photonic crystals.
Probing statistical properties of Anderson localization with quantum emitters
Smolka, Stephan; Sapienza, Luca; Lehmann, Tau B; Rix, Kristian R; Froufe-Pérez, Luis S; García, Pedro D; Lodahl, Peter
2011-01-01
Wave propagation in disordered media can be strongly modified by multiple scattering and wave interference. Ultimately the so-called Anderson-localized regime is reached when the waves become strongly confined in space. So far, Anderson localization of light has been probed in transmission experiments by measuring the intensity of an external light source after propagation through a disordered medium. However, discriminating between Anderson localization and losses in these experiments remains a major challenge. Here we present an alternative approach where we use quantum emitters embedded in disordered photonic crystal waveguides as light sources. Anderson-localized modes are efficiently excited and the analysis of the photoluminescence spectra allows to explore their statistical properties paving a way for controlling Anderson localization in disordered photonic crystals.
Anderson localization in the seventies and beyond
David Thouless
2009-01-01
Little attention was paid to Anderson's challenging paper on localization for the first ten years, but from 1969 onwards it generated a lot of interest. Around that time a number of challenging questions were raised by the community, on matters such as the existence of a sharp distinction between localized and extended states, or between conductors and insulators. For some
Anderson Localization in the Seventies and Beyond
David Thouless
2010-01-01
Little attention was paid to Anderson's challenging paper on localization for the first ten years, but from 1968 onwards it generated a lot of interest. Around that time a number of important questions were raised by the community, on matters such as the existence of a sharp distinction between localized and extended states, or between conductors and insulators. For some
Anderson localization in QCD-like theories
Matteo Giordano; Tamas G. Kovacs; Ferenc Pittler
2014-09-18
We review the present status of the Anderson transition in the spectrum of the Dirac operator of QCD-like theories on the lattice. Localized modes at the low-end of the spectrum have been found in SU(2) Yang-Mills theory with overlap and staggered valence fermions as well as in Nf=2+1 QCD with staggered quarks. We draw an analogy between the transition from localized to delocalized modes in the Dirac spectrum and the Anderson transition in electronic systems. The QCD transition turns out to be in the same universality class as the transition in the corresponding Anderson model. We also speculate on the possible physical relevance of this transition to QCD at high temperature and the possible finite temperature phase transition in QCD-like models with different fermion contents.
Bistability of anderson localized States in nonlinear random media.
Shadrivov, Ilya V; Bliokh, Konstantin Y; Bliokh, Yuri P; Freilikher, Valentin; Kivshar, Yuri S
2010-03-26
We study wave transmission through one-dimensional random nonlinear structures and predict a novel effect resulting from an interplay of nonlinearity and disorder. We reveal that, while weak nonlinearity does not change the typical exponentially small transmission in the regime of the Anderson localization, it affects dramatically the disorder-induced localized states excited inside the medium leading to bistable and nonreciprocal resonant transmission. Our numerical modeling shows an excellent agreement with theoretical predictions based on the concept of a high-Q resonator associated with each localized state. This offers a new way for all-optical light control employing statistically homogeneous random media without regular cavities. PMID:20366536
Numerical studies on the Anderson localization problem
J. Stein; U. Krey
1981-01-01
The Anderson localization transition has been studied by numerical methods for very large two- and three-dimensional samples with up to 30 000 sites, varying both the energy and the strength of disorder of the electronic system, which is described by a tight-binding Hamiltonian with both diagonal and off-diagonal disorder. By an orthogonal transformation, the system is mapped numerically onto an
Anderson localization of light with topological dislocations
NASA Astrophysics Data System (ADS)
Lobanov, Valery E.; Kartashov, Yaroslav V.; Vysloukh, Victor A.; Torner, Lluis
2013-11-01
We predict Anderson localization of light with nested screw topological dislocations propagating in disordered two-dimensional arrays of hollow waveguides illuminated by vortex beams. The phenomenon manifests itself in the statistical presence of topological dislocations in ensemble-averaged output distributions accompanying standard disorder-induced localization of light spots. Remarkably, screw dislocations are captured by the light spots despite the fast and irregular transverse displacements and topological charge flipping undertaken by the dislocations due to the disorder. The statistical averaged modulus of the output local topological charge depends on the initial vorticity carried by the beam.
Resonant enhancement of Anderson localization: analytical approach.
Herrera-González, I F; Izrailev, F M; Makarov, N M
2013-11-01
We study localization properties of the eigenstates and wave transport in a one-dimensional system consisting of a set of barriers and/or wells of fixed thickness and random heights. The inherent peculiarity of the system resulting in the enhanced Anderson localization is the presence of the resonances emerging due to the coherent interaction of the waves reflected from the interfaces between the wells and/or barriers. Our theoretical approach allows to derive the localization length in infinite samples both out of the resonances and close to them. We examine how the transport properties of finite samples can be described in terms of this length. It is shown that the analytical expressions obtained by standard methods for continuous random potentials can be used in our discrete model, in spite of the presence of resonances that cannot be described by conventional theories. All our results are illustrated with numerical data manifesting an excellent agreement with the theory. PMID:24329215
Anderson localization in the seventies and beyond
NASA Astrophysics Data System (ADS)
Thouless, David
2009-03-01
Little attention was paid to Anderson's challenging paper on localization for the first ten years, but from 1969 onwards it generated a lot of interest. Around that time a number of challenging questions were raised by the community, on matters such as the existence of a sharp distinction between localized and extended states, or between conductors and insulators. For some of these questions the answers are unambiguous. There certainly are energy ranges in which states are exponentially localized, in the presence of a static disordered potential. In a one-diensional potential all states are localized. There is clear evidence, in three dimensions, for energy ranges in which states are extended and diffusive. Magnetic and spin-dependent interactions play an important part in reducing localization effects. For massive particles like electrons and atoms the lowest energy states are localized, but for massless particles like photons and acoustic phonons the lowest energy states are extended. In a one-dimensional disordered system all states are localized. Uncertainties remain. Scaling theory shows that in two-dimensional systems all states are weakly localized, and that there is no minimum metallic conductivity. The interplay between disorder and mutual interactions is still an area of uncertainty, which is very important for electronic systems. Optical and dilute atomic systems provide experimental tests which allow interaction to be much less important. The quantum Hall effect provided a system where states on the Fermi surface are localized, but non-dissipative currents flow in response to an electric field.
Anderson Localization in the Seventies and Beyond
NASA Astrophysics Data System (ADS)
Thouless, David
Little attention was paid to Anderson's challenging paper on localization for the first ten years, but from 1968 onwards it generated a lot of interest. Around that time a number of important questions were raised by the community, on matters such as the existence of a sharp distinction between localized and extended states, or between conductors and insulators. For some of these questions the answers are unambiguous. There certainly are energy ranges in which states are exponentially localized, in the presence of a static disordered potential. In a weakly disordered one-dimensional potential, all states are localized. There is clear evidence, in three dimensions, for energy ranges in which states are extended, and ranges in which they are diffusive. Magnetic and spin-dependent interactions play an important part in reducing localization effects. For massive particles like electrons and atoms the lowest energy states are localized, but for massless particles like photons and acoustic phonons the lowest energy states are extended. Uncertainties remain. Scaling theory suggests that in two-dimensional systems all states are weakly localized, and that there is no minimum metallic conductivity. The interplay between disorder and mutual interactions is still an area of uncertainty, which is very important for electronic systems. Optical and dilute atomic systems provide experimental tests which allow interaction to be much less important. The quantum Hall effect provided a system where states on the Fermi surface are localized, but non-dissipative currents flow in response to an electric field.
Microwave driven atoms: from Anderson localization to Einstein's photo effect
Schelle, Alexej; Buchleitner, Andreas
2008-01-01
We study the counterpart of Anderson localization in driven one-electron Rydberg atoms. By changing the initial Rydberg state at fixed microwave frequency and interaction time, we numerically monitor the crossover from Anderson localization to the photo effect in the atomic ionization signal.
Anderson localization in metamaterials and other complex media (Review Article)
NASA Astrophysics Data System (ADS)
Gredeskul, Sergey A.; Kivshar, Yuri S.; Asatryan, Ara A.; Bliokh, Konstantin Y.; Bliokh, Yuri P.; Freilikher, Valentin D.; Shadrivov, Ilya V.
2012-07-01
This is a review of some recent (mostly ours) results on Anderson localization of light and electron waves in complex disordered systems, including: (i) left-handed metamaterials, (ii) magnetoactive optical structures, (iii) graphene superlattices, and (iv) nonlinear dielectric media. First, we demonstrate that left-handed metamaterials can significantly suppress localization of light and lead to an anomalously enhanced transmission. This suppression is essential at the long-wavelength limit in the case of normal incidence, at specific angles of oblique incidence (Brewster anomaly), and in vicinity of zero-? or zero-? frequencies for dispersive metamaterials. Remarkably, in disordered samples comprised of alternating normal and left-handed metamaterials, the reciprocal Lyapunov exponent and reciprocal transmittance increment can differ from each other. Second, we study magnetoactive multilayered structures, which exhibit nonreciprocal localization of light depending on the direction of propagation and on polarization. At resonant frequencies or realizations such nonreciprocity results in effectively unidirectional transport of light. Third, we discuss the analogy between wave propagation through multilayered samples with metamaterials and charge transport in graphene, which provides a simple physical explanation of unusual conductive properties of disordered graphene superlatices. We predict disorder-induced resonance of the transmission coefficient at oblique incidence of Dirac quasiparticles. Finally, we demonstrate that an interplay of nonlinearity and disorder in dielectric media can lead to bistability of individual localized states excited inside the medium at resonant frequencies. This results in nonreciprocity of wave transmission and unidirectional transport of light.
Anderson localization in Nb/Al superconducting bilayers
Greco, M.; Lacquaniti, V.; Maggi, S.; Menichetti, E.; Rinaudo, G.
2000-01-01
The authors have measured the temperature dependence of resistivity in relatively thick Nb/Al bilayers fabricated at room temperature, observing the decrease of {rho} for increasing T typical of Anderson localization in disordered systems. The authors report the experimental conditions which determine this behavior and compare it to theoretical models for localization in 3D systems.
Critical transport and anomalously localized states at the Anderson transition
H. Obuse; K. Yakubo
2003-01-01
The effect of anomalously localized states (ALS) for electron transport at the critical point of the Anderson transition is numerically investigated for two-dimensional symplectic systems. Defining ALS quantitatively, it is found that a probability of finding ALS at criticality increases with the system size, and saturates in an infinite system. This remarkable feature influences transport properties at criticality.
Super-diffusion in optical realizations of Anderson localization
NASA Astrophysics Data System (ADS)
Krivolapov, Yevgeny; Levi, Liad; Fishman, Shmuel; Segev, Mordechai; Wilkinson, Michael
2012-04-01
We discuss the dynamics of particles in one dimension in potentials that are random in both space and time. The results are applied to recent optics experiments on Anderson localization, in which the transverse spreading of a beam is suppressed by random fluctuations in the refractive index. If the refractive index fluctuates along the direction of the paraxial propagation of the beam, the localization is destroyed. We analyze this broken localization in terms of the spectral decomposition of the potential. When the potential has a discrete spectrum, the spread is controlled by the overlap of Chirikov resonances in phase space. As the number of Fourier components is increased, the resonances merge into a continuum, which is described by a Fokker-Planck equation. We express the diffusion coefficient in terms of the spectral intensity of the potential. For a general class of potentials that are commonly used in optics, the solutions to the Fokker-Planck equation exhibit anomalous diffusion in phase space, implying that when Anderson localization is broken by temporal fluctuations of the potential, the result is transport at a rate similar to a ballistic one or even faster. For a class of potentials which arise in some existing realizations of Anderson localization, atypical behavior is found.
Anderson localization and the theory of dirty superconductors
NASA Technical Reports Server (NTRS)
Kapitulnik, A.; Kotliar, G.
1985-01-01
A study is made of the effect of Anderson localization in dirty superconductors. The scale dependence of the diffusion in the vicinity of the mobility edge results in a strong renormalization of the zero-temperature coherence length. This implies the breakdown of the Ginzburg criterion close to the metal-insulator transition and thus the importance of fluctuations in this regime. The upper critical field is calculated, and possible experiments are also discussed.
Wegner estimate and Anderson localization for random magnetic fields
Laszlo Erdoes; David Hasler
2010-12-23
We consider a two dimensional magnetic Schroedinger operator with a spatially stationary random magnetic field. We assume that the magnetic field has a positive lower bound and that it has Fourier modes on arbitrarily short scales. We prove the Wegner estimate at arbitrary energy, i.e. we show that the averaged density of states is finite throughout the whole spectrum. We also prove Anderson localization at the bottom of the spectrum.
Anderson localization and breakdown of hydrodynamics in random ferromagnets
Bruinsma, R.; Coppersmith, S.N.
1986-05-01
The dynamic structure factor of Heisenberg magnets with weak randomness is computed. Under circumstances which are explained in detail, we find failure of hydrodynamic theory in the longitudinal structure factor due to localization of spin waves. Localization induces a power-law dependence on q and ..omega.. for the neutron scattering line shape near magnetic Bragg spots. The exponent describing the power law is related to the correlation-length exponent of Anderson localization. Random anisotropy magnets appear to be promising candidates for experimental investigations.
Destruction of Anderson localization by a weak nonlinearity
A. S. Pikovsky; D. L. Shepelyansky
2007-08-24
We study numerically a spreading of an initially localized wave packet in a one-dimensional discrete nonlinear Schr\\"odinger lattice with disorder. We demonstrate that above a certain critical strength of nonlinearity the Anderson localization is destroyed and an unlimited subdiffusive spreading of the field along the lattice occurs. The second moment grows with time $ \\propto t^\\alpha$, with the exponent $\\alpha$ being in the range $0.3 - 0.4$. For small nonlinearities the distribution remains localized in a way similar to the linear case.
Transversal Anderson localization of sound in acoustic waveguide arrays.
Ye, Yangtao; Ke, Manzhu; Feng, Junheng; Wang, Mudi; Qiu, Chunyin; Liu, Zhengyou
2015-04-22
We present designs of one-dimensional acoustic waveguide arrays and investigate wave propagation inside. Under the condition of single identical waveguide mode and weak coupling, the acoustic wave motion in waveguide arrays can be modeled with a discrete mode-coupling theory. The coupling constants can be retrieved from simulations or experiments as the function of neighboring waveguide separations. Sound injected into periodic arrays gives rise to the discrete diffraction, exhibiting ballistic or extended transport in transversal direction. But sound injected into randomized waveguide arrays readily leads to Anderson localization transversally. The experimental results show good agreement with simulations and theoretical predictions. PMID:25812602
Transversal Anderson localization of sound in acoustic waveguide arrays
NASA Astrophysics Data System (ADS)
Ye, Yangtao; Ke, Manzhu; Feng, Junheng; Wang, Mudi; Qiu, Chunyin; Liu, Zhengyou
2015-04-01
We present designs of one-dimensional acoustic waveguide arrays and investigate wave propagation inside. Under the condition of single identical waveguide mode and weak coupling, the acoustic wave motion in waveguide arrays can be modeled with a discrete mode-coupling theory. The coupling constants can be retrieved from simulations or experiments as the function of neighboring waveguide separations. Sound injected into periodic arrays gives rise to the discrete diffraction, exhibiting ballistic or extended transport in transversal direction. But sound injected into randomized waveguide arrays readily leads to Anderson localization transversally. The experimental results show good agreement with simulations and theoretical predictions.
Anderson localization and Mott insulator phase in the time domain.
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
Anderson localization and Mott insulator phase in the time domain
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
Photon transport enhanced by transverse Anderson localization in disordered superlattices
NASA Astrophysics Data System (ADS)
Hsieh, P.; Chung, C.; McMillan, J. F.; Tsai, M.; Lu, M.; Panoiu, N. C.; Wong, C. W.
2015-03-01
Controlling the flow of light at subwavelength scales provides access to functionalities such as negative or zero index of refraction, transformation optics, cloaking, metamaterials and slow light, but diffraction effects severely restrict our ability to control light on such scales. Here we report the photon transport and collimation enhanced by transverse Anderson localization in chip-scale dispersion-engineered anisotropic media. We demonstrate a photonic crystal superlattice structure in which diffraction is nearly completely arrested by cascaded resonant tunnelling through transverse guided resonances. By modifying the geometry of more than 4,000 scatterers in the superlattices we add structural disorder controllably and uncover the mechanism of disorder-induced transverse localization. Arrested spatial divergence is captured in the power-law scaling, along with exponential asymmetric mode profiles and enhanced collimation bandwidths for increasing disorder. With increasing disorder, we observe the crossover from cascaded guided resonances into the transverse localization regime, beyond both the ballistic and diffusive transport of photons.
Ferrimagnetism and single-particle excitations in a periodic Anderson model on the honeycomb lattice
NASA Astrophysics Data System (ADS)
Seki, Kazuhiro; Shirakawa, Tomonori; Zhang, Qinfang; Li, Tao; Yunoki, Seiji
2015-04-01
By using the variationalcluster approximation and cluster perturbation theory, we investigate the magnetism and single-particle excitations of a periodic Anderson model on the honeycomb lattice as an effective model for the single-side hydrogenated graphene, namely, graphone. We calculate the magnetic moment as a function of U (Coulomb interaction on impurity sites) with showing that the ground state is ferrimagneticfor any U > 0. We then calculate the single-particle excitations and show that the single-particle excitations are gapless and exhibit quadratic dispersion relation near the Fermi energy.
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.
B. H. Brandow
1986-01-01
A variational study of ground states of the orbitally nondegenerate Anderson lattice model, using a wave function with one variational parameter per Bloch state k, has been extended to deal with essentially metallic systems having a nonintegral number of electrons per site. Quasiparticle excitations are obtained by direct appeal to Landau's original definition for interacting Fermi liquids, scrEqp(k,sigma)=deltaEtotal\\/deltan qp(k,sigma). This
B. Brandow
1986-01-01
A variational study of ground states of the orbitally nondegenerate Anderson lattice model, using a wave function with one variational parameter per Bloch state k, has been extended to deal with essentially metallic systems having a nonintegral number of electrons per site. Quasiparticle excitations are obtained by direct appeal to Landau's original definition for interacting Fermi liquids, scrE\\/sub qp\\/(k,sigma) =
Asymmetric Anderson model and spin excitations in the Kondo insulator YbB{sub 12}
Barabanov, A. F., E-mail: abarabanov@mtu-net.r [Russian Academy of Sciences, Institute for High-Pressure Physics (Russian Federation); Maksimov, L. A. [Kurchatov Institute Russian Research Center (Russian Federation)
2009-07-15
A cluster problem is analyzed as an example demonstrating that the observed three-mode behavior of spin-triplet excitations in YbB{sub 12} can be described by the asymmetric Anderson model with insulating singlet ground state. In the case of an infinite system, it is argued that the behavior of the f subsystem can be analyzed by using an effective Hamiltonian H{sub J} with direct antiferromagnetic f-f exchange interaction. The spin excitation spectrum is shown to have a minimum at the antiferromagnetic vector, as observed experimentally. A distinctive feature of the analysis is the use of singlet and triplet basis operators.
Anderson localization and the topology of classifying spaces
NASA Astrophysics Data System (ADS)
Morimoto, Takahiro; Furusaki, Akira; Mudry, Christopher
2015-06-01
We construct the generic phase diagrams encoding the topologically distinct localized and delocalized phases of noninteracting fermionic quasiparticles for any symmetry class from the tenfold way in one, two, and three dimensions. To this end, we start from a massive Dirac Hamiltonian perturbed by a generic disorder for any dimension of space and for any one of the ten symmetry classes from the tenfold way. The physics of Anderson localization is then encoded by a two-dimensional phase diagram that we deduce from the topology of the space of normalized Dirac masses. This approach agrees with previously known results and gives an alternative explanation for the even-odd effect in the one-dimensional chiral symmetry classes. We also give a qualitative explanation for the Gade singularity and Griffiths effects in the density of states using the first homotopy group of the normalized Dirac masses in two dimensions. Finally, this approach is used to analyze the stability of massless Dirac fermions on the surface of three-dimensional topological crystalline insulators.
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
Mean-field theory and ? expansion for Anderson localization
NASA Astrophysics Data System (ADS)
Harris, A. B.; Lubensky, T. C.
1981-03-01
A general field-theoretic formulation of the Anderson model for the localization of wave functions in a random potential is given in terms of n-component replicated fields in the limit n-->0, and is analyzed primarily for spatial dimension d>=4. Lengths ?1 and ?2 associated with the spatial decay of correlations in the single-particle and two-particle Green's functions, respectively, are introduced. Two different regimes, the weak coupling and strong coupling, are distinguished depending on whether ?-11 or ?-12, respectively, vanishes as the mobility energy, Ec, is approached. The weak-coupling regime vanishes as d-->4+. Mean-field theory is developed from the uniform minimum of the Lagrangian for both the strong- and weak-coupling cases. For the strong-coupling case it gives the exponents va=14, ?a=?a=12, ?=0, and ?=1, where ?a is the exponent associated with the density of extended states and ? is that associated with the conductivity. Simple heuristic arguments are used to verify the correctness of these unusual mean-field values. Infrared divergences in perturbation theory for the strong-coupling case occur for d<8, and an ? expansion (?=8-d) is developed which is found to be identical to that previously analyzed for the statistics of lattice animals and which gives ?a=12-?12, ?=-?9, va=14+?36, and ?=1-5?36. The results are consistent with the Ward identity, which in combination with scaling arguments requires that ?a+?a=1. The treatment takes account of the fact that the average of the on-site Green's function [G(x-->,x-->E)]av is nonzero and is predicated on this quantity being real, i.e., on the density of states vanishing at the mobility edge. We also show that localized states emerge naturally from local minima of finite action in the Lagrangian. These instanton solutions are analyzed on a lattice where the cutoff produced by the lattice constant leads to lattice instantons which exist for all d, in contrast to the case for the continuum model where instanton solutions seem not to occur for d>4. This analysis leads to a density of localized states ?loc satisfying ln?loc~-E2 at large E and ln?loc~-|E-Ec|-? at the mobility edge, where for the weak-coupling case ?=(12)(d-4) and for the strong-coupling case ?=(d-2+?)va-2?a=12+?18 for d<8 and ?=(14)(d-6) for d>8. A brief discussion of the relationship between this work and the theories of localization below four dimensions is presented.
Anderson attractors in active arrays
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.
Image transport through a disordered optical fibre mediated by transverse Anderson localization
NASA Astrophysics Data System (ADS)
Karbasi, Salman; Frazier, Ryan J.; Koch, Karl W.; Hawkins, Thomas; Ballato, John; Mafi, Arash
2014-02-01
Transverse Anderson localization of light allows localized optical-beam-transport through a transversely disordered and longitudinally invariant medium. Its successful implementation in disordered optical fibres recently resulted in the propagation of localized beams of radii comparable to that of conventional optical fibres. Here we demonstrate optical image transport using transverse Anderson localization of light. The image transport quality obtained in the polymer disordered optical fibre is comparable to or better than some of the best commercially available multicore image fibres with less pixelation and higher contrast. It is argued that considerable improvement in image transport quality can be obtained in a disordered fibre made from a glass matrix with near wavelength-size randomly distributed air-holes with an air-hole fill-fraction of 50%. Our results open the way to device-level implementation of the transverse Anderson localization of light with potential applications in biological and medical imaging.
Observation of migrating transverse Anderson localizations of light in nonlocal media.
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
Wang, Wei Hua
Topological Superconductor to Anderson Localization Transition in One-Dimensional Incommensurate.--Topological superconductors (TSCs) have attracted intense recent studies, as they are promising candidates for the practical feasibility on the detection of Majorana fermions in hybrid superconductor-semiconductor wires [8Â10], which
Light focusing in the Anderson Regime
Leonetti, Marco; Mafi, Arash; Conti, Claudio
2014-01-01
Anderson localization is a regime in which diffusion is inhibited and waves (also electromagnetic waves) get localized. Here we exploit adaptive optics to achieve focusing in disordered optical fibers in the Anderson regime. By wavefront shaping and optimization, we observe the generation of a propagation invariant beam, where light is trapped transversally by disorder, and show that Anderson localizations can be also excited by extended speckled beams. We demonstrate that disordered fibers allow a more efficient focusing action with respect to standard fibers in a way independent of their length, because of the propagation invariant features and cooperative action of transverse localizations.
Light focusing in the Anderson regime
NASA Astrophysics Data System (ADS)
Leonetti, Marco; Karbasi, Salman; Mafi, Arash; Conti, Claudio
2014-07-01
Anderson localization is a regime in which diffusion is inhibited and waves (also electromagnetic waves) get localized. Here we exploit adaptive optics to achieve focusing in disordered optical fibres in the Anderson regime. By wavefront shaping and optimization, we observe the generation of a propagation-invariant beam, where light is trapped transversally by disorder, and show that Anderson localizations can be also excited by extended speckled beams. We demonstrate that disordered fibres allow a more efficient focusing action with respect to standard fibres in a way independent of their length, because of the propagation-invariant features and cooperative action of transverse localizations.
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.
Observation of Anderson Localization in Ultrathin Films of Three-Dimensional Topological Insulators.
Liao, Jian; Ou, Yunbo; Feng, Xiao; Yang, Shuo; Lin, Chaojing; Yang, Wenmin; Wu, Kehui; He, Ke; Ma, Xucun; Xue, Qi-Kun; Li, Yongqing
2015-05-29
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 (Bi_{1-x}Sb_{x})_{2}Te_{3} 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. PMID:26066450
Evolution of locally excited avalanches in semiconductors
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.
NASA Astrophysics Data System (ADS)
Smaranda, Ion; Mihut, Lucian; Baibarac, Mihaela; Baltog, Ioan; Lefrant, Serge
2014-09-01
We demonstrate that under continuous single-beam excitation, one can generate an abnormal anti-Stokes Raman emission (AASRE) whose properties are similar to a coherent anti-Stokes Raman scattering. The effect has been observed in mesoscopic materials, which possess intrinsically nonlinear properties [lithium niobate (LiNbO3), bismuth germanium oxide (Bi12GeO20; BGO), bismuth silicon oxide (Bi12GeO20; BSO)], which have a nonzero electric susceptibility of the third order, ?(3)?0. Corroborated Raman and coherent backscattering studies demonstrate that the occurrence of both effects is conditioned by the existence of a mesoscopic morphology of the sample, which is able to ensure efficient transport of the light inside the sample through a multiple light scattering mechanism. In this context, both AASRE and coherent backscattering effects are because of the Anderson localization of the light.
Linear and Nonlinear Anderson Localization in a Curved Potential
NASA Astrophysics Data System (ADS)
Claudio, Conti
2014-03-01
Disorder induced localization in the presence of nonlinearity and curvature is investigated. The time-resolved three-dimensional expansion of a wave packet in a bent cigar shaped potential with a focusing Kerr-like interaction term and Gaussian disorder is numerically analyzed. A self-consistent analytical theory, in which randomness, nonlinearity and geometry are determined by a single scaling parameter, is reported, and it is shown that curvature enhances localization.
Anderson Localization for a Multi-Particle Quantum Graph
Mostafa Sabri
2013-07-18
We study a multi-particle quantum graph with random potential. Taking the approach of multiscale analysis we prove exponential and strong dynamical localization of any order in the Hilbert-Schmidt norm near the spectral edge. Apart from the results on multi-particle systems, we also prove Lifshitz-type asymptotics for single-particle systems. This shows in particular that localization for single-particle quantum graphs holds under a weaker assumption on the random potential than previously known.
Local Optical Excitations in Metals
NASA Astrophysics Data System (ADS)
Gibbs, Laurence Kay Doon
Core spectra of p('6) (--->) p('5)s excitations of rare gas, halogen, and alkali impurities located on the surface and in the bulk of host alkali and Mg metals are presented. The data were obtained by means of differential reflectance spectroscopy in the energy range 5-20 eV using synchrotron radiation. In striking contrast to the absorption profiles of the pure alkalis, linear redshifted profiles are observed at dilution for rare gas adsorbates on alkali surfaces, for Cs adsorbed on Mg, and for Cs dispersed in bulk Na as an alloy. When Cs is dispersed in bulk K the sharp edge characteristic of the pure alkalis is observed. The spectra of Cs and Rb adsorbates on alkali surfaces mirror these same trends, but retain a distinct atomic character. A central result of the present research is that the linear profile may be associated with strong coupling of the excitation to the conduction electrons. A criterion for strong coupling is given which depends on the degree to which the excited impurity level mixes with the host conduction band. There is not at present any theory which can explain these observations. Spectra of halogen adsorbates on alkali and Mg surfaces are also presented; it is found that the ground configuration of isolated halogen atoms on these surfaces is ionic. All the impurity-metal complexes are studied at high concentration when impurity-impurity interactions are important.
Disorder-limited photon propagation and Anderson-localization in photonic crystal waveguides
NASA Astrophysics Data System (ADS)
Wasley, N. A.; Luxmoore, I. J.; Coles, R. J.; Clarke, E.; Fox, A. M.; Skolnick, M. S.
2012-07-01
We investigate the disorder-limited propagation of photons in photonic crystal waveguides in the slow-light regime. We use analysis of Fabry-Perot resonances to map the mode dispersion and extract the photon localization length. Propagation lengths are deduced to be limited to less than 20 ?m for group index >50. Anderson-localized modes are observed at high group indices, when the localization lengths are shorter than the waveguide lengths, consistent with the Fabry-Perot analysis. The results have consequences for integrated quantum-dot single-photon circuits which rely on slow-light effects to enhance emission rates.
Anderson localization and Brewster anomalies in photonic disordered quasiperiodic lattices.
Reyes-Gómez, E; Bruno-Alfonso, A; Cavalcanti, S B; Oliveira, L E
2011-09-01
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. PMID:22060519
Anderson localization and Brewster anomalies in photonic disordered quasiperiodic lattices
Reyes-Gomez, E. [Instituto de Fisica, Universidad de Antioquia, AA 1226, Medellin (Colombia); Bruno-Alfonso, A. [Faculdade de Ciencias, UNESP-Universidade Estadual Paulista, 17033-360 Bauru-SP (Brazil); Cavalcanti, S. B. [Instituto de Fisica, Universidade Federal de Alagoas, 57072-970 Maceio-AL (Brazil); Oliveira, L. E. [Instituto de Fisica, Universidade Estadual de Campinas-UNICAMP, 13083-859 Campinas-SP (Brazil)
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.
NASA Astrophysics Data System (ADS)
Chebrolu, Narasimha Raju; Chatterjee, Ashok
2014-09-01
A single-level Anderson-Holstein model is investigated in the presence of a magnetic field. Employing a Lang-Firsov transformation followed by a zero-phonon averaging, an effective Anderson model is obtained, which is then solved by using the Kikuchi-Morita Cluster variation (CV) method as adopted by Bose and Tanaka in the case of Anderson model. The effect of electron-phonon interaction on the binding energy between a magnetic impurity electron and the conduction electrons and on the local magnetic moment are investigated at zero temperature in the presence of an external magnetic field.
Karbasi, Salman; Frazier, Ryan J; Mirr, Craig R; Koch, Karl W; Mafi, Arash
2013-01-01
We develop and characterize a disordered polymer optical fiber that uses transverse Anderson localization as a novel waveguiding mechanism. The developed polymer optical fiber is composed of 80,000 strands of poly (methyl methacrylate) (PMMA) and polystyrene (PS) that are randomly mixed and drawn into a square cross section optical fiber with a side width of 250 ?m. Initially, each strand is 200 ?m in diameter and 8-inches long. During the mixing process of the original fiber strands, the fibers cross over each other; however, a large draw ratio guarantees that the refractive index profile is invariant along the length of the fiber for several tens of centimeters. The large refractive index difference of 0.1 between the disordered sites results in a small localized beam radius that is comparable to the beam radius of conventional optical fibers. The input light is launched from a standard single mode optical fiber using the butt-coupling method and the near-field output beam from the disordered fiber is imaged using a 40X objective and a CCD camera. The output beam diameter agrees well with the expected results from the numerical simulations. The disordered optical fiber presented in this work is the first device-level implementation of 2D Anderson localization, and can potentially be used for image transport and short-haul optical communication systems. PMID:23929276
Probing Anderson localization of light by weak non-linear effects
NASA Astrophysics Data System (ADS)
Sperling, T.; Bührer, W.; Ackermann, M.; Aegerter, C. M.; Maret, G.
2014-11-01
Breakdown of wave transport due to strong disorder is a universal phenomenon known as Anderson localization (AL). It occurs because of the macroscopic population of reciprocal multiple scattering paths, which in three dimensional systems happens at a critical scattering strength. Intensities on these random loops should thus be highly increased relative to those of a diffusive sample. In order to highlight localized modes of light, we exploit the optical nonlinearities of TiO2. Power dependent and spectrally resolved time of flight distribution measurements in transmission through slabs of TiO2 powders at various turbidities reveal that mostly long loops are affected by nonlinearities and that the deviations from diffusive transport observed at long times are due to these localized modes. Our data are a first step in the experimental investigation of the interplay between nonlinear effects and AL in 3D.
Anderson localization of polaron states Franz X. Bronold 1,2 and Holger Fehske 3,2
Fehske, Holger
Anderson localization of polaron states Franz X. Bronold 1,2 and Holger Fehske 3,2 1 Institut fu# Using the vanishing of the typical polaron tunneling rate as an indicator of the breakdown of itinerancy, we study the localization of polaron states in a generic model for a disordered polaronic material
Localized excitations in UPdSn
NASA Astrophysics Data System (ADS)
Nakotte, H.; Bull, M.; McEwen, K. A.; Robinson, R. A.; Swan, T.; Kelley, T. M.; Eccleston, R. S.; Brück, E.
1998-04-01
We have measured the inelastic-neutron-scattering response of UPdSn using the HET and PHAROS spectrometers at the ISIS and LANSCE facilities, respectively. UPdSn shows some quasielastic scattering, which may be attributed to the hybridization of the 5f-electrons with the conduction electrons. We also find a clear excitation around 40 meV above 40 K. This excitation may be indicative of localized crystal fields in UPdSn, but its strong temperature dependence seems to contradict a simple crystal-field picture. Below TN, an 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 TN.
Localized excitations in UPdSn
NASA Astrophysics Data System (ADS)
Nakotte, H.; Bull, M.; McEwen, K. A.; Robinson, R. A.; Swan, T.; Kelley, T. M.; Eccleston, R. S.; Brück, E.
We have measured the inelastic-neutron-scattering response of UPdSn using HET and PHAROS spetrometers at the ISIS and LANSCE facilities, respectively. UPdSn shows some quasielastic scattering, which may be attributed to the hybridization of the 5f-electrons with the conduction electrons. We also find a clear excitation around 40 meV above 40 K. This excitation may be indicative of localized crystal fields in UPdSn, but its strong temperature dependence seems to contradict a simple crystal-field picture. Below TN, an 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 mechanim(s) may contribute above TN.
Kim, Kihong
2015-06-01
The propagation and the Anderson localization of electromagnetic waves in a randomly-stratified slab, where both the dielectric permittivity and the magnetic permeability depend on one spatial coordinate in a random manner, is theoretically studied. The case where the wave impedance is uniform, while the refractive index is random, is considered in detail. The localization length and the disorder-averaged transmittance of s and p waves incident obliquely on the slab are calculated as a function of the incident angle ? and the strength of randomness in a numerically precise manner, using the invariant imbedding method. It is found that the waves incident perpendicularly on the slab are delocalized, while those incident obliquely are localized. As the incident angle increases from zero, the localization length decreases from infinity monotonically to some finite value. The localization length is found to depend on the incident angle as ?^{-4} and a simple analytical formula, which works quite well for weak disorder and small incident angles, is derived. The localization length does not depend on the wave polarization, but the disorder-averaged transmittance generally does. PMID:26072812
Localized excitations in UPdSn
Nakotte, H.; Robinson, R.A.; Swan, T.; Kelley, T. [Los Alamos National Lab., NM (United States). Manuel Lujan Jr. Neutron Scattering Center; Bull, M. [Univ. of London (United Kingdom); [Univ. of Amsterdam (Netherlands). Van der Waals-Zeeman Inst.; McEwen, K.A. [Univ. of London (United Kingdom); Ecclestone, R.A. [Rutherford Appleton Lab., Chilton (United Kingdom). ISIS Div.; Brueck, E. [Univ. of Amsterdam (Netherlands). Van der Waals-Zeeman Inst.
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.
NASA Astrophysics Data System (ADS)
Javan Mard, Hossein; Dobrosavljevi?, Vladimir; Hoyos, José A.; Miranda, Eduardo
2015-03-01
We implement an efficient strong-disorder renormalization group (SDRG) procedure for disordered tight-binding models in dimension D >= 3 , including the localization properties on Erd?s-Rényi random graphs, which represent an appropriate infinite dimensional limit. Our dramatically improved SDRG algorithm is based on a judicious elimination of most (irrelevant) new bonds generated under RG. It yields excellent agreement with exact numerical results for universal properties at the critical point, without significant increase of the required computer time, even as the spatial dimension is increased beyond D = 3 . This opens an efficient avenue to explore the critical properties of Anderson transition in the strong-coupling limit of high spatial dimensions.
NASA Astrophysics Data System (ADS)
Kang, Joongoo; Wei, Su-Huai
2014-03-01
We present a mechanism for reversible switching of the Anderson localization (AL) of electrons in hydrogenated graphene through modulation of the H coverage on graphene by external electric fields. The main idea is to exploit the unique acid-base chemistry (i.e., proton transfer reaction) between NH3 gas and hydrogenated graphene, which can be controlled by applying perpendicular electric fields. The proposed field-induced control of disorder in hydrogenated graphene not only has scientific merits in a systematic study of AL of electrons in grapheme but can also lead to new insight into the development of a new type of transistor based on reversible on/off switching of AL. Furthermore, the reversible and effective tuning of the H coverage on graphene should be useful for tailoring material properties of weakly hydrogenated graphene. This work was funded by the NREL LDRD program (DE-AC36-08GO28308).
Drabold, David
Electron hopping between localized states: A simulation of the finite-temperature Anderson problem- ficiently disordered one-band model. Sophisticated hopping theory2Â4 proposes that the quantum jump the process of hopping or ``phonon-induced delocalization.'' The hopping6 we describe is correctly between
Kravtsov, V.E., E-mail: kravtsov@ictp.it [Abdus Salam International Centre for Theoretical Physics, P.O. Box 586, 34100 Trieste (Italy); Landau Institute for Theoretical Physics, 2 Kosygina st., 117940 Moscow (Russian Federation); Yudson, V.I., E-mail: yudson@isan.troitsk.ru [Institute for Spectroscopy, Russian Academy of Sciences, 142190 Troitsk, Moscow reg. (Russian Federation)
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.
NASA Astrophysics Data System (ADS)
Shi, Zhou; Wang, Jing; Genack, Azriel
2012-02-01
We report measurements of spectra of the field transmission matrix t for microwave radiation propagating through waveguide filled with randomly positioned dielectric scattering spheres in the Anderson localization transition. Diagonalizing the matrix product tt^ gives the transmission eigenvalues ?n, which yields the optical transmittance, T=?a,b=1^N | tba |^2 =?n=1^N ?n . The ensemble average of the transmittance is equal to the dimensionless conductance, g=
Localized excitations of charged dust grains in dusty plasma lattices
Kourakis, Ioannis; Shukla, Padma Kant [Institut fuer Theoretische Physik IV, Fakultaet fuer Physik und Astronomie, Ruhr-Universitaet Bochum, D-44780 Bochum (Germany); Basios, Vassileios [U.L.B. - Universite Libre de Bruxelles, Centre for Nonlinear Phenomena and Complex Systems, C.P. 231 Physique Statistique et Plasmas, Boulevard du Triomphe, B-1050 Brussels (Belgium)
2005-10-31
The nonlinear aspects of charged dust grain motion in a one-dimensional dusty plasma (DP) monolayer are discussed. Both horizontal (longitudinal, acoustic mode) and vertical (transverse, optic mode) displacements are considered, and various types of localized excitations are reviewed, in a continuum approximation. Dust crystals are shown to support nonlinear kink-shaped supersonic longitudinal solitary excitations, as well as modulated envelope (either longitudinal or transverse) localized modes. The possibility for Discrete Breather (DB-) type excitations (Intrinsic Localized Modes, ILMs) to occur is investigated, from first principles. These highly localized excitations owe their existence to lattice discreteness, in combination with the interaction and/or substrate (sheath) potential nonlinearity. This possibility may open new directions in DP- related research. The relation to previous results on atomic chains as well as to experimental results on strongly-coupled dust layers in gas discharge plasmas is discussed.
NASA Astrophysics Data System (ADS)
Roundy, R. C.; Nemirovsky, D.; Kagalovsky, V.; Raikh, M. E.
2014-06-01
Motivated by recent experiments, where the tunnel magnetoresitance (TMR) of a spin valve was measured locally, we theoretically study the distribution of TMR along the surface of magnetized electrodes. We show that, even in the absence of interfacial effects (like hybridization due to donor and acceptor molecules), this distribution is very broad, and the portion of area with negative TMR is appreciable even if on average the TMR is positive. The origin of the local sign reversal is quantum interference of subsequent spin-rotation amplitudes in the course of incoherent transport of carriers between the source and the drain. We find the distribution of local TMR exactly by drawing upon formal similarity between evolution of spinors in time and of the reflection coefficient along a 1D chain in the Anderson model. The results obtained are confirmed by the numerical simulations.
Sprik, Rudolf
medium where the scat- tering is efficient enough to induce localization has been the reason why only few characterization of the scattering and absorption is needed to understand the transport of light in strongly scat of the scat- tering properties and the optical absorption in Ge powders close to the Anderson localization
Shi, Zhou; Wang, Jing; Genack, Azriel Z.
2014-01-01
The nature of transport of electrons and classical waves in disordered systems depends upon the proximity to the Anderson localization transition between freely diffusing and localized waves. The suppression of average transport and the enhancement of relative fluctuations in conductance in one-dimensional samples with lengths greatly exceeding the localization length, , are related in the single-parameter scaling (SPS) theory of localization. However, the difficulty of producing an ensemble of statistically equivalent samples in which the electron wave function is temporally coherent has so-far precluded the experimental demonstration of SPS. Here we demonstrate SPS in random multichannel systems for the transmittance T of microwave radiation, which is the analog of the dimensionless conductance. We show that for , a single eigenvalue of the transmission matrix (TM) dominates transmission, and the distribution of the is Gaussian with a variance equal to the average of , as conjectured by SPS. For samples in the cross-over to localization, , we find a one-sided distribution for . This anomalous distribution is explained in terms of a charge model for the eigenvalues of the TM ? in which the Coulomb interaction between charges mimics the repulsion between the eigenvalues of TM. We show in the localization limit that the joint distribution of T and the effective number of transmission eigenvalues determines the probability distributions of intensity and total transmission for a single-incident channel. PMID:24516156
NASA Astrophysics Data System (ADS)
Wang, Pei; Sun, Qing-feng; Xie, X. C.
2014-10-01
The Floquet topological superconducting state is a nonequilibrium time-periodic state hosting Majorana fermions. We study its transport properties by using the Kitaev model with time-periodic incommensurate potentials, which experiences phase transition from the Floquet topological superconducting phase to the Anderson localized phase with increasing driving strength. We study both the real time dynamics of the current and the nonanalytic behavior of the tunneling conductance at the transition. Especially, we find that the tunneling conductance changes continuously at the transition, being a finite value in the presence of Floquet-Majorana fermions, but drops to zero as the Majorana fermions vanish. For a special choice of parameters, the Majorana fermions revive at a larger driving strength, accompanied by the revival of conductances.
Ryu, Shinsei; Mudry, Christopher; Obuse, Hideaki; Furusaki, Akira
2007-09-14
We discuss, for a two-dimensional Dirac Hamiltonian with a random scalar potential, the presence of a Z2 topological term in the nonlinear sigma model encoding the physics of Anderson localization in the symplectic symmetry class. The Z2 topological term realizes the sign of the Pfaffian of a family of Dirac operators. We compute the corresponding global anomaly, i.e., the change in the sign of the Pfaffian by studying a spectral flow numerically. This Z2 topological effect can be relevant to graphene when the impurity potential is long ranged and, also, to the two-dimensional boundaries of a three-dimensional lattice model of Z2 topological insulators in the symplectic symmetry class. PMID:17930456
Magnetoresistance of an Anderson Insulator of Bosons
NASA Astrophysics Data System (ADS)
Gangopadhyay, Anirban; Galitski, Victor; Müller, Markus
2013-07-01
We study the magnetoresistance of two-dimensional bosonic Anderson insulators. We describe the change in spatial decay of localized excitations in response to a magnetic field, which is given by an interference sum over alternative tunneling trajectories. The excitations become more localized with increasing field (in sharp contrast to generic fermionic excitations which get weakly delocalized): the localization length ?(B) is found to change as ?-1(B)-?-1(0)˜B4/5. The quantum interference problem maps onto the classical statistical mechanics of directed polymers in random media (DPRM). We explain the observed scaling using a simplified droplet model which incorporates the nontrivial DPRM exponents. Our results have implications for a variety of experiments on magnetic-field-tuned superconductor-to-insulator transitions observed in disordered films, granular superconductors, and Josephson junction arrays, as well as for cold atoms in artificial gauge fields.
Enhanced Electromagnetic Chirality by Locally Excited Surface Plasmon Polaritons
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...
Impurity-assisted nanoscale localization of plasmonic excitations in graphene
NASA Astrophysics Data System (ADS)
Muniz, Rodrigo A.; Dahal, Hari P.; Balatsky, A. V.; Haas, Stephan
2010-08-01
A nonlocal quantum-mechanical model is employed to compute plasmonic excitations of graphene in the presence of an impurity potential. A full diagonalization of the polarization operator is performed, allowing the extraction of all its poles. It is demonstrated that impurities induce the formation of nanoscale localized plasmonic modes. It is also shown that the chemical potential and impurity strength can be tuned to control target features of the localized modes, making graphene an intrinsic plasmonic material. These predictions can be tested by scanning tunneling microscopy experiments.
2014-01-01
At The University of Texas MD Anderson Cancer Center, we have used sonography (US) extensively for more than 2 decades to refine the local and regional staging of invasive breast cancer. Although magnetic resonance imaging is superior to all other imaging modalities in the measurement of the primary tumor and detection of additional foci of malignancy, in our experience US has shown sufficient accuracy in clinical practice to stage most invasive breast cancers. The exceptions are ill-defined tumors such as invasive lobular cancers and tumors in breasts containing extensive diffuse benign disease. An advantage of US is that multifocality or multicentricity can be confirmed via US-guided fine-needle aspiration within 15 minutes and the information shared immediately with the patient and the breast surgeon or medical oncologist. US has also proved indispensable in the evaluation of lymphatic spread because it can evaluate more nodal basins (e.g., the supraclavicular fossa and low neck) than magnetic resonance imaging can and because it can guide needle biopsy to confirm the status of any indeterminate node (including internal mammary nodes) within minutes. PMID:24309983
Measurement-induced disturbance near Anderson localization in one-dimensional systems
NASA Astrophysics Data System (ADS)
Cheng, W. W.; Shan, C. J.; Gong, L. Y.; Zhao, S. M.
2014-09-01
We study the localization transition in several typical one-dimensional single-particle systems by means of measurement-induced disturbance (MID). The results show that the MID presents a rapid drop around the boundary between the localized state and extended ones, and the corresponding first-order derivative exhibits a behavior of divergence around the critical point for deterministic on-site potential systems (e.g. the quasi-periodic model). These characteristics can capture a phase diagram as well as the traditional method. For the non-deterministic on-site systems (e.g. the random dimer model), the states around the resonant energies possess relatively large values for MID, which means that they are extended. In addition, as the random potential ? b exceeds the critical value, the states possessing a large MID vanish completely. These results show that MID can be useful in detecting localization transition in these typical one-dimensional systems.
Nevill Mott; M. Pepper; S. Pollitt; R. H. Wallis; C. J. Adkins
1975-01-01
An outline is given of the electrical properties expected in a disordered solid or fluid which shows a metal-insulator transition of Anderson type. This is one in which the Fermi energy of the electrons passes through a mobility edge separating extended states from states localized by disorder, as the composition or some other parameter is changed. Some of the experimental
2012-01-01
metamaterials Ara A. Asatryan,1 Lindsay C. Botten,1 Michael A. Byrne,1 Valentin D. Freilikher,2 Sergey A, one-dimensional stacks composed of dispersive metamaterials and normal materials are presented that the localization of waves in random stacks composed entirely of either metamaterial or normal dielectric layers
Matter wave transport and Anderson localization in anisotropic three-dimensional disorder
NASA Astrophysics Data System (ADS)
Piraud, Marie; Pezzé, Luca; Sanchez-Palencia, Laurent
2012-09-01
We study quantum transport of matter waves in anisotropic three-dimensional disorder. First, we show that structured correlations can induce rich effects, such as anisotropic suppression of the white-noise limit and inversion of the transport anisotropy. Second, we show that the localization threshold (mobility edge) is strongly affected by a disorder-induced shift of the energy states, which we calculate. Our work is directly relevant to ultracold-matter waves in optical disorder, and implications on recent experiments are discussed. It also offers scope for further studies of anisotropy effects in other systems with controlled disorder, where counterparts of the discussed effects can be expected.
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.
Typical density of states as an order parameter for the Anderson localization
NASA Astrophysics Data System (ADS)
Tam, Ka-Ming; Moore, Conrad; Moreno, Juana; Jarrell, Mark
2015-03-01
The typical medium theory and its recently proposed extensions for models with off-diagonal disorder and multiple bands are significant progress towards the study of localization phenomenon in real materials. The fundamental assumption of these methods is that the typical density of states can be treated as an order parameter. However, its justifications in lattice model is largely lacking. This is predominantly due to two factors. First, the lattice sizes amenable for exact diagonalization is rather limited. Second, the small lattice sizes lead to a very sensitive dependence on the broadening factor. In this work, we use the kernel polynomial method to perform simulation for large system sizes. By adapting the method for the study of criticality, we find that the typical density of states has a well defined finite size scaling behavior. In particular, from the kurtosis, Binder ratio, of the distribution of the density of states for different lattice sizes, we find a clear crossing to identify the critical point. This provides further support that the typical density of states can be used as an order parameter for the localization transition.
Lasting depression in corticomotor excitability associated with local scalp cooling.
Tremblay, François; Remaud, Anthony; Mekonnen, Abeye; Gholami-Boroujeny, Shiva; Racine, Karl-Édouard; Bolic, Miodrag
2015-07-23
In this study, we investigated the effect of local scalp cooling on corticomotor excitability with transcranial magnetic simulation (TMS). Participants (healthy male adults, n=12) were first assessed with TMS to derive baseline measure of excitability from motor evoked potentials (MEPs) using the right first dorsal interosseous as the target muscle. Then, local cooling was induced on the right hemi-scalp (upper frontal region ?15cm(2)) by means of a cold wrap. The cooling was maintained for 10-15min to get a decrease of at least 10°C from baseline temperature. In the post-cooling period, both scalp temperature and MEPs were reassessed at specific time intervals (i.e., T0, T10, T20 and T30min). Scalp surface temperatures dropped on average by 12.5°C from baseline at T0 (p<0.001) with partial recovery at T10 (p<0.05) and full recovery at T20. Parallel analysis of post-cooling variations in MEP amplitude revealed significant reductions relative to baseline at T0, T10 and T20. No concurrent change in MEP latency was observed. A secondary control experiment was performed in a subset of participants (n=5) to account for the mild discomfort associated with the wrapping procedure without the cooling agent. Results showed no effect on any of the dependent variables (temperature, MEP amplitude and latency). To our knowledge, this report provides the first neurophysiological evidence linking changes in scalp temperature with lasting changes in corticomotor excitability. PMID:26067406
Parametric excitation of multiple resonant radiations from localized wavepackets.
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
Parametric excitation of multiple resonant radiations from localized wavepackets
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
Localized collective excitations in doped graphene in strong magnetic fields
Fischer, Andrea M.; Roemer, Rudolf A. [Department of Physics and Centre for Scientific Computing, University of Warwick, Coventry CV4 7AL (United Kingdom); Dzyubenko, Alexander B. [Department of Physics, California State University-Bakersfield, Bakersfield, California 93311 (United States); General Physics Institute, Russian Academy of Sciences, Moscow 119991 (Russian Federation)
2009-10-15
We consider collective excitations in graphene with filled Landau levels (LL's) in the presence of an external potential due to a single charged donor D{sup +} or acceptor A{sup -} impurity. We show that localized collective modes split off the magnetoplasmon continuum and, in addition, quasibound states are formed within the continuum. A study of the evolution of the strengths and energies of magneto-optical transitions is performed for integer filling factors {nu}=1,2,3,4 of the lowest LL. We predict impurity absorption peaks above as well as below the cyclotron resonance. We find that the single-particle electron-hole symmetry of graphene leads to a duality between the spectra of collective modes for the D{sup +} and A{sup -}. The duality shows up as a set of the D{sup +} and A{sup -} magnetoabsorption peaks having the same energies but active in different circular polarizations.
NASA Astrophysics Data System (ADS)
He, Shanjin
1990-01-01
In this thesis, experimental studies of the effects of Anderson localization in a one-dimensional random system and of physical properties of a two-dimensional quasiperiodic system by using acoustic analog techniques are reported. The acoustic simulation of Anderson localization involves a string/mass system. The wave field consists of transverse waves in the the string generated with an electromechanical actuator. The Bloch-wave behavior is verified with the masses spaced periodically. In the study of localization effects, the positions of the masses are varied. Several sets of measurements are made with the positions randomly varied within maximum displacements from lattice sites of 1%, 2%, and 5% of the lattice constant. Inelastic scattering effects in the localization problem are studied with 2% spacing disorder. In this investigation, a measured hopping probability of inelastic scattering as a function of the longitudinal drive amplitude is obtained. Some phase-correlation effects are evident. The acoustic simulation experiment used to investigate the physical properties of quasicrystals involved coupled oscillators in a two-dimensional Penrose lattice. By analogy with a tight-binding model, the tuning forks mounted at the centers of the rhombuses of the Penrose tile as local oscillators are nearest-neighbor-coupled together with arcs of steel wire connecting the tines of neighboring tuning forks. The oscillations of the system is driven by an electromagnet. The responses of the system are monitored by electrodynamic transducers. The eigenvalue spectrum shows a feature resulting from the quasiperiodic symmetry: the spectrum has gaps and bands whose widths are in the ratio of the Golden Mean (surd{5 + 1 })/2. The eigenfunctions of the system are obtained.
Surface plasmon polaritons locally excited on the ridges of metallic gratings
Boyer, Edmond
Surface plasmon polaritons locally excited on the ridges of metallic gratings B. Wang*, and P the surface plasmon polaritons that are locally excited on the ridges (between the indentations) of metallic by an intuitive microscopic model that shines new light on the role of surface plasmons in the transmission
NASA Astrophysics Data System (ADS)
Kettemann, S.; Mucciolo, E. R.; Varga, I.; Slevin, K.
2012-03-01
Dilute magnetic impurities in a disordered Fermi liquid are considered close to the Anderson metal-insulator transition (AMIT). Critical power-law correlations between electron wave functions at different energies in the vicinity of the AMIT result in the formation of pseudogaps of the local density of states. Magnetic impurities can remain unscreened at such sites. We determine the density of the resulting free magnetic moments in the zero-temperature limit. While it is finite on the insulating side of the AMIT, it vanishes at the AMIT, and decays with a power law as function of the distance to the AMIT. Since the fluctuating spins of these free magnetic moments break the time-reversal symmetry of the conduction electrons, we find a shift of the AMIT, and the appearance of a semimetal phase. The distribution function of the Kondo temperature TK is derived at the AMIT, in the metallic phase, and in the insulator phase. This allows us to find the quantum phase diagram in an external magnetic field B and at finite temperature T. We calculate the resulting magnetic susceptibility, the specific heat, and the spin relaxation rate as a function of temperature. We find a phase diagram with finite-temperature transitions among insulator, critical semimetal, and metal phases. These new types of phase transitions are caused by the interplay between Kondo screening and Anderson localization, with the latter being shifted by the appearance of the temperature-dependent spin-flip scattering rate. Accordingly, we name them Kondo-Anderson transitions.
Localized Excited Charge Carriers Generate Ultrafast Inhomogeneous Strain in the Multiferroic BiFeO3
Evans, Paul G.
to monitor the lattice dynamics in a thin film of multiferroic BiFeO3 after above-band-gap photoexcitationLocalized Excited Charge Carriers Generate Ultrafast Inhomogeneous Strain in the Multiferroic BiFeO of existing models of photogenerated stresses in BiFeO3: the relevant excited charge carriers must remain
Local Excitation, Scattering, and Interference of Surface Plasmons
B. Hecht; H. Bielefeldt; L. Novotny; Y. Inouye; D. W. Pohl
1996-01-01
The optical probe of a scanning near-field optical microscope is shown to act as a point source of surface plasmon (SP) polaritons on gold and silver films. Plasmon excitation manifests itself by emission of light in the direction of the SP resonance angle, originating from an area with the shape of a dipole radiation pattern whose extension is given by
Rényi entropy of locally excited states with thermal and boundary effect in 2D CFTs
NASA Astrophysics Data System (ADS)
Guo, Wu-Zhong; He, Song
2015-04-01
We study Rényi 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 Rényi entropy is summation of contribution from thermal effect and local excitation. Secondly, we mainly study the Rényi entropy of locally excited states in 2D CFT with a boundary. We show that the time evolution of Rényi entropy is affected by the boundary, but does not depend on the boundary condition. Moreover, we show that the maximal value of Rényi entropy always coincides with the log of quantum dimension of the primary operator. In terms of quasi-particle interpretation, the boundary behaves as an infinite potential barrier which reflects any energy moving towards it.
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
J. Phys. Chem. B 1998, 102, 3310-3315 Localized Electronic Excitations in Phenylacetylene Dendrimers
Tretiak, Sergei
optical excitation of conjugated dendrimers (fractal antenna macromolecules) are shown to be localized attention [17]. The dy- namics of photophysical (electronic and vibrational en- ergy transfer) as well to anticipate this local- ization by inspecting the molecular orbitals: The sys- tem is conjugated
Local excitations in thin metal films bounded by topological insulators
NASA Astrophysics Data System (ADS)
Granada E, J. C.; Rojas, D. F.
2014-12-01
Electromagnetic excitations arising in a metal slab surrounded by an insulator with a non-trivial topology associated to time reversal symmetry (topological insulator) are described. It is shown that the topological term induces modifications to the dispersion relations of bounding and antibounding surface modes in the long wavelength non-retarded limit which depend on the square of the topological term. In particular, it is shown that a backward wave arises with a group velocity undergoing a relative change which is independent of the film thickness. It is shown that the rotation of the polarization plane induced by the non-trivial topology is a linear function of the topological term for all slab thickness.
Excited state localization in organic molecules consisting of conjugated and nonconjugated segments
E. Zojer; P. Buchacher; F. Wudl; J. Cornil; J. Ph. Calbert; J. L. Brédas; G. Leising
2000-01-01
We investigate, both experimentally and theoretically, a series of novel molecules consisting of conjugated segments (such as stilbene, naphthylene, and anthrylene) that are separated from each other by nonconjugated bridges. Excited state localization effects are studied theoretically by post-Hartree-Fock calculations-taking into account electron correlation effects. In this context, we compute the electron-hole two-particle wave functions for the prominent excited states
Iwata, Suehiro
2008-12-18
Based on the locally projected molecular orbitals, the third and fourth order perturbation corrections for the molecular interaction within the single excitations are evaluated, and the calculated interaction energies are compared with the counterpoise (CP) corrected interaction energy of the Hartree-Fock level of theory. It is demonstrated that the third order calculation is a practical and powerful method to obtain the binding energy almost equal to the CP corrected energy. It requires only one more two-electron integral handling after the LP MO calculation, which is faster than a usual supermolecule HF calculation. For the perturbation expansion, the absolutely local excited orbitals are determined. For small basis sets, it is shown that the partial delocalization of the absolutely local excited orbitals is a compromizing technique to take into account the charge-transfer contribution without reintroducing a large basis set superposition error. PMID:19367996
Transport of quantum excitations via local and nonlocal fluctuations
NASA Astrophysics Data System (ADS)
Zhang, M.; Lee, Tony E.; Sadeghpour, H. R.
2015-05-01
In quantum systems, one usually seeks to minimize dephasing noise and disorder. The efficiency of transport in a quantum system is usually degraded by the presence of noise and disorder. However, it has been shown that the combination of the two can lead to significantly more efficiency than each by itself. Here, we consider how the addition of nonlocal noise, in the form of incoherent hopping, affects the transport efficiency. We show that incoherent hopping introduces additional local extrema in the efficiency function and investigate how the transport dynamics crosses over from a quantum random walk to a classical random walk.
Rényi entropy of locally excited states with thermal and boundary effect in 2D CFTs
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.
Localized and propagating excitations in gapped phases of spin systems with bond disorder
NASA Astrophysics Data System (ADS)
Utesov, O. I.; Sizanov, A. V.; Syromyatnikov, A. V.
2014-10-01
Using the conventional T-matrix approach, we discuss gapped phases in one-, two-, and three-dimensional (3D) spin systems (both with and without a long-range magnetic order) with bond disorder and with weakly interacting bosonic elementary excitations. This work is motivated by recent experimental and theoretical activity in spin-liquid-like systems with disorder and in the disordered interacting boson problem. In particular, we apply our theory to both paramagnetic low-field and fully polarized high-field phases in dimerized spin-1/2 systems and in integer-spin magnets with large single-ion easy-plane anisotropy D with disorder in exchange coupling constants (and/or D). The elementary excitation spectrum and the density of states are calculated in the first order in defects concentration c ?1. In 2D and 3D systems, the scattering on defects leads to a finite damping of all propagating excitations in the band except for states lying near its edges. We demonstrate that the analytical approach is inapplicable for states near the band edges and our numerical calculations reveal their localized nature. We find that the damping of propagating excitations can be much more pronounced in considered systems than in magnetically ordered gapless magnets with impurities. In 1D systems, the disorder leads to localization of all states in the band, while those lying far from the band edges (short-wavelength excitations) can look like conventional wave packets.
Localized excitations in dusty plasma crystals: A survey of theoretical results
Ioannis Kourakis; Padma Kant Shukla; V. Koukouloyannis; B. Farokhi
2008-01-01
The nonlinear aspects of dust motion in one- (1D) and two-dimensional (2D) dust lattices are reviewed. Horizontal (longitudinal, acoustic) as well as vertical (transverse, optic-like) dust grain motion in 1D monolayer is studied. Dust crystals are shown to support nonlinear kink-shaped solitary excitations (density solitons), related to longitudinal (in-plane) dust grain displacement, as well as modulated envelope localized modes associated
Localized Hartree-Fock density-functional calculation of atomic inner-shell excitation
Zhongyuan Zhou
2005-01-01
We present a spin-dependent localized Hartree-Fock (LHF) density-functional theoretical (DFT) approach for the accurate calculation of the electronic energies of atomic inner-shell excited states. In this approach, electron spin-orbitals are obtained by solving Kohn-Sham (KS) equation with a spin-dependent LHF exchange potential and Lee-Yang-Parr correlation potential. A generalized pseudospectral (GPS) technique, allowing non-uniform spatial discretization, is used for high precision
NSDL National Science Digital Library
Hot on the heels of AltaVista's Raging Search (see the May 5, 2000 Scout Report) comes another returned and (somewhat) slimmed-down search engine that focuses on relevant results. Like Raging Search, Excite's new Precision Search uses Google-style link analysis technology ("Deep Analysis") to help identify the most useful sites. Test queries produced consistently relevant results among the top few returns, though an indication of the number of total returns would be helpful, with two banner ads and (in some but not all cases) a Quick Results box on the left that could be quite handy for consumer-related searching. For instance, a search for "Plymouth" yielded links to research and comparisons, blue book values, financing, and service and repair information in the Quick Results box. I was also pleased to see that clicking on one of the other search categories (category, news, photo, audio/video) instantly produces returns for the original query, though the photo databases available seem somewhat limited compared to, say, AltaVista. While users searching for "official" sites will still do best at Google, those who also search for additional resources such as news, photos, and audio/video content may wish to give Excite Precision a run-through.
Modeling of ion-acoustic soliton excitation through decay process of a localized perturbation
Pajouh, H. Hakimi [Department of Physics, Alzahra University, Tehran 19834 (Iran, Islamic Republic of); Abbasi, H. [Faculty of Physics, Amirkabir University of Technology, P. O. Box 15875-4413, Tehran (Iran, Islamic Republic of)
2008-08-15
The possibility of the nonlinear decay of a localized perturbation into the ion-acoustic solitons is studied. The present paper is a theoretical attempt to model the experimental soliton excitation [S. Yi et al., Phys. Plasmas 4, 2436 (1997)] in which solitons are excited by a grid modulating near the ion plasma frequency. It has been reported that a localized wave was created near the grid that would decay nonlinearly into the ion-acoustic soliton and a wave packet [T. E. Sheridan et al., Phys. Plasmas 5, 3165 (1998)]. For this purpose, an unbounded plasma composed of the cold positively charged ions and hot electrons is considered. Electron trapping is included in the model as the result of their nonlinear resonant interaction with the localized potential well. A Gaussian initial perturbation is used to model the localized perturbation. The numerical calculation through a modified Korteweg-de Vries equation simulates the decay of the initial Gaussian perturbation into several ion-acoustic solitons and a wave packet. It is shown that the electron trapping has an essential influence on the decay process.
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.
Ultrahigh Enhancement of Electromagnetic Fields by Exciting Localized with Extended Surface Plasmons
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...
Localization of nonlinear damage using state-space-based predictions under stochastic excitation
NASA Astrophysics Data System (ADS)
Liu, Gang; Mao, Zhu; Todd, Michael; Huang, Zongming
2014-02-01
This paper presents a study on localizing damage under stochastic excitation by state-space-based methods, where the damaged response contains some nonlinearity. Two state-space-based modeling algorithms, namely auto- and cross-predictions, are employed in this paper, and the greatest prediction error will be achieved at the sensor pair closest to the actual damage, in terms of localization. To quantify the distinction of prediction error distributions obtained at different sensor locations, the Bhattacharyya distance is adopted as the quantification metric. There are two lab-scale test-beds adopted as validation platforms, including a two-story plane steel frame with bolt loosening damage and a three-story benchmark aluminum frame with a simulated tunable crack. Band-limited Gaussian noise is applied through an electrodynamic shaker to the systems. Testing results indicate that the damage detection capability of the state-space-based method depends on the nonlinearity-induced high frequency responses. Since those high frequency components attenuate quickly in time and space, the results show great capability for damage localization, i.e., the highest deviation of Bhattacharyya distance is coincident with the sensors close to the physical damage location. This work extends the state-space-based damage detection method for localizing damage to a stochastically excited scenario, which provides the advantage of compatibility with ambient excitations. Moreover, results from both experiments indicate that the state-space-based method is only sensitive to nonlinearity-induced damage, thus it can be utilized in parallel with linear classifiers or normalization strategies to insulate the operational and environmental variability, which often affects the system response in a linear fashion.
Critical excitation spectrum of a quantum chain with a local three-spin coupling.
McCabe, John F; Wydro, Tomasz
2011-09-01
Using the phenomenological renormalization group (PRG), we evaluate the low-energy excitation spectrum along the critical line of a quantum spin chain having a local interaction between three Ising spins and longitudinal and transverse magnetic fields, i.e., a Turban model. The low-energy excitation spectrum found with the PRG agrees with the spectrum predicted for the (D(4),A(4)) conformal minimal model under a nontrivial correspondence between translations at the critical line and discrete lattice translations. Under this correspondence, the measurements confirm a prediction that the critical line of this quantum spin chain and the critical point of the two-dimensional three-state Potts model are in the same universality class. PMID:22060344
Relativistic Coulomb excitation within the time dependent superfluid local density approximation.
Stetcu, I; Bertulani, C A; Bulgac, A; Magierski, P; Roche, K J
2015-01-01
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 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, the dipole pygmy resonance, and giant quadrupole modes are excited during the process. 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. PMID:25615463
Regular and irregular patterns of self-localized excitation in arrays of coupled phase oscillators.
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
Regular and irregular patterns of self-localized excitation in arrays of coupled phase oscillators
NASA Astrophysics Data System (ADS)
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.
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.
Schick, Daniel; Herzog, Marc; Wen, Haidan; Chen, Pice; Adamo, Carolina; Gaal, Peter; Schlom, Darrell G; Evans, Paul G; Li, Yuelin; Bargheer, Matias
2014-03-01
We apply ultrafast x-ray diffraction with femtosecond temporal resolution to monitor the lattice dynamics in a thin film of multiferroic BiFeO3 after above-band-gap photoexcitation. The sound-velocity limited evolution of the observed lattice strains indicates a quasi-instantaneous photoinduced stress which decays on a nanosecond time scale. This stress exhibits an inhomogeneous spatial profile evidenced by the broadening of the Bragg peak. These new data require substantial modification of existing models of photogenerated stresses in BiFeO3: the relevant excited charge carriers must remain localized to be consistent with the data. PMID:24655276
NASA Astrophysics Data System (ADS)
Asahi, Tsuyoshi; Matsuo, Yasutaka; Masuhara, Hiroshi
1996-07-01
Transient absorption spectra of the durene-pyromellitic dianhydride (PMDA) charge transfer (CT) crystal, PMDA-doped durene crystal and its molten state were measured by femtosecond diffuse reflectance spectroscopy, and electronic structure and dynamics of the excited state in the CT crystal are discussed. It is directly confirmed that the excited CT singlet state is almost localized (self-trapped) in one donor(D)-acceptor(A) unit within a few picoseconds after excitation. The electronic structure of the excited state is quite polar but it is not an electron transfer state from D to A.
Mechanisms of distributed and localized excitation of unsteady Görtler modes by free-stream vortices
NASA Astrophysics Data System (ADS)
Ivanov, A. V.; Kachanov, Y. S.; Mischenko, D. A.
2014-12-01
The present study is devoted to the investigation of several, presumably most efficient, mechanisms of the production of non-stationary Görtler vortices in a laminar boundary layer on a concave wall due to scattering of 2D and 3D free-stream vortices by streamwise localized 3D and 2D surface and flow non-uniformities. The experiments were carried out by means of the method of controllable non-stationary disturbances. The interaction of downstream-propagating 3D free-stream vortices with the growing boundary layer, presenting natural 2D bas-flow non-uniformity, was found to lead to a rather efficient excitation of unsteady Görtler modes. This mechanism of distributed receptivity is able to modify considerably the growth rates of the excited Görtler vortices in comparison with the linear stability laws. In the present paper, definitions of the coefficients of distributed vortical receptivity are given and some estimates of values of these coefficients are reported. In spite of a high measurement accuracy and a rather broad range of examined parameters, no excitation of Görtler vortices due to other examined mechanisms was identified.
Acoustically Coupled Droplet Combustion and Local Extinction under High Amplitude Excitation
NASA Astrophysics Data System (ADS)
Tran, Phuoc Hai Nguyen
The present experimental study examined the characteristics of liquid ethanol fuel droplet combustion in the presence of high amplitude acoustic excitation, with focus on conditions where high local flame strain can result in the periodic partial extinction and reignition within the flame front in time. These partial extinction phenomena were observed via phase-locked OH* chemiluminescence imaging and identified by the cycle of sudden, severe drop-off in chemiluminescent intensity near the flame stagnation region followed by reignition at the stagnation flame front at a later portion of the acoustic cycle. For increased excitation levels, the burning rate constant values were higher than those for both baseline quiescent and moderate excitation conditions. The experimental acoustic acceleration values were also higher than those for moderate excitation levels. Furthermore, as observed in past studies, these measurements of acoustic acceleration agreed only qualitatively with predictions from the acoustic radiation force theory. The presence of periodic partial extinction did not alter these expected trends. The temporal response in flame luminosity to flow perturbations was also analyzed using the Rayleigh index to determine the degree of thermoacoustic coupling inherent in a burning droplet system for given forcing conditions. When partial extinction was absent, the integrated OH* chemiluminescent intensity oscillated nearly in phase with the pressure perturbation. This led to a positive Rayleigh index, indicating unstable combustion, as was observed in previous studies at moderate excitation. However, partial extinction phenomena altered the relationship between measured intensity and pressure perturbations: the intensity oscillated nearly out of phase with the pressure perturbation. This led to a negative Rayleigh index, indicating stable combustion despite clear evidence of thermoacoustic coupling in the combustion footage and in the combustion property trends. These results indicated that the characterization of thermoacoustic coupling is important to the description of any droplet combustion system undergoing acoustic excitation; however, they also suggested that the Rayleigh index, at least when quantified using OH* chemiluminescence, may not fully capture the nature of thermoacoustic coupling in regimes where partial extinction phenomena occur.
Chen, Xin; Silbey, Robert J
2011-05-12
The non-markovian effect of a fluctuating environment plays an important role in electronic excitation transfer in organic disordered media, such as light-harvesting systems and conjugated polymers. Stochastic Liouville equations (SLE) are used to study the interaction between excitons and the environment. We model the non-markovian environment phenomenologically with a dichotomic process. An exact approach to solve the SLE based on Shapiro and Loginov's differentiation formulas allows us to rigorously study the effect of the non-markovian environment on excitation energy transfer, such as coherence conservation and its implication for transfer efficiency. This simple SLE model goes beyond the perturbative second-order master equation valid for both the weak coupling and short time correlation conditions. In addition, we discuss why our non-markovian model is a good approximation to the SLE model driven by the stationary Gauss-Markov process (Ornstein-Uhlenbeck process) over a broad range of fluctuation strengths and correlation times. Numerical results based on our SLE model for dimeric aggregates and the Fenna-Matthews-Olson (FMO) complex reveal the important interplay of intermolecular coupling, correlation time, and fluctuation strength, and their effects on the exciton relaxation process due to the environmental phonon. The results also uncover the connection between localization and motional narrowing, and the efficiency of electronic excitation transfer, demonstrating that the non-markovian environment is critical for chromophore aggregates to achieve an optimal transfer rate in a noisy environment and to contribute to the robustness of the FMO excitation energy transfer network. PMID:21384851
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.
Gruner, Daniel S.
MgB2 nonlinear properties investigated under localized high rf magnetic field excitation Tamin Tai localized rf magnetic fields. Because of the presence of the small superconducting gap in the band magnetic field, created by a magnetic write head, is integrated into our nonlinear-Meissner-effect scanning
How Local Excitation–Inhibition Ratio Impacts the Whole Brain Dynamics
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
Zhongyuan Zhou; Shih-I. Chu
2007-01-01
We present a spin-dependent localized Hartree-Fock (SLHF) density-functional approach for the treatment of inner-shell excited states of open-shell atomic systems. In this approach, the electron spin-orbitals and single-Slater-determinant energies of an electronic configuration are computed by solving the Kohn-Sham (KS) equation with SLHF exchange potential. The multiplet energy of an inner-shell excited state is evaluated from the single-Slater-determinant energies in
Andreas K. Theophilou; Petros G. Papaconstantinou
2000-01-01
The main objective of this paper is to investigate the applicability of the subspace density-functional theory (SDFT) for the calculation of excited-state energies. The exchange and correlation energy density functionals, Exc(rho), used in the present calculation are local and depend on the polarizability parameter zeta=2S\\/N. The deviations of the calculated excited-state energies from their corresponding experimental values range from 0.1%
Locally focused 3D coronary imaging using volume-selective RF excitation.
Yang, G Z; Burger, P; Gatehouse, P D; Firmin, D N
1999-01-01
This paper describes a locally focused magnetic resonance (MR) imaging method for three-dimensional (3D) zonal echoplanar coronary angiography using volume-selective radiofrequency (RF) excitation. Spatially variable resolution was used for delineating coronary arteries and reducing the effect of residual signals caused by the imperfect excitation profile of the RF pulse. The use of variable resolution enabled the derivation of basis functions having different spatial characteristics pertaining to regional object details, and a significantly smaller number of phase-encoded signal measurements was needed for image reconstruction. Based on the relative significance of each required phase-encoding step, real-time phase-encode reordering was used to minimize the effect of respiratory motion during coronary imaging. To eliminate Nyquist ghosting in oblique echoplanar imaging, the echoplanar data acquired during forward and reverse echoes were reconstructed separately and then averaged with spatial registration for improving the signal-to-noise ratio. The technique was evaluated with phantom experiments and right coronary artery images of 11 asymptomatic volunteers using a 0.5 T MR system. A marked improvement in image quality has been achieved despite a 30% reduction in imaging time. PMID:10025626
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.
Gogan, P; Schmiedel-Jakob, I; Chitti, Y; Tyc-Dumont, S
1995-01-01
The spatial distribution of depolarized patches of membrane during the excitation of single neurons in culture has been recorded with a high spatial resolution (1 micron2/pixel) imaging system based on a liquid-nitrogen-cooled astronomical camera mounted on an inverted microscope. Images were captured from rat nodose neurons stained with the voltage-sensitive dye RH237. Conventional intracellular microelectrode recordings were made in synchrony with the images. During an action potential the fluorescence changes occurred in localized, unevenly distributed membrane areas, which formed clusters of depolarized sites of different sizes and intensities. When fast conductances were blocked by the addition of tetrodotoxin, a reduction in the number and the intensities of the depolarized sites was observed. The blockade by tetrodotoxin of voltage-clamped neurons also reduced the number of depolarized sites, although the same depolarizing voltage step was applied. Similarly, when a voltage-clamped neuron was depolarized by a constant-amplitude voltage step, the number of depolarized sites varied according to the degree of activation of the voltage-sensitive channels, which was modified by changing the holding potential. These results suggest that the spatial patterns of depolarization observed during excitation are related to the operations of ionic channels in the membrane. Images FIGURE 1 FIGURE 2 FIGURE 4 FIGURE 5 FIGURE 6 FIGURE 7 PMID:8527643
NASA Astrophysics Data System (ADS)
Rasmussen, K. Ø.; Christiansen, P. L.; Johansson, M.; Gaididei, Yu. B.; Mingaleev, S. F.
1998-03-01
A one-dimensional discrete nonlinear Schrödinger (DNLS) model with the power dependence, r- s on the distance r, of dispersive interactions is proposed. The stationary states of the system are studied both analytically and numerically. Two kinds of trial functions, exp-like and sech-like are exploited and the results of both approaches are compared. Both on-site and inter-site stationary states are investigated. It is shown that for s sufficiently large all features of the model are qualitatively the same as in the DNLS model with nearest-neighbor interaction. For s less than some critical value, scr, there is an interval of bistability where two stable stationary states exist at each excitation number. The bistability of on-site solitons may occur for dipole-dipole dispersive interaction ( s = 3), while scr for inter-site solitions is close to 2.1. In the framework of the DNLS equation with nearest-neighbor coupling we discuss the stability of highly localized, “breather-like”, excitations under the influence of thermal fluctuations. Numerical analysis shows that the lifetime of the breather is always finite and in a large parameter region inversely proportional to the noise variance for fixed damping and nonlinearity. We also find that the decay rate of the breather decreases with increasing nonlinearity and with increasing damping.
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
Romero, M. J.; van de Lagemaat, J.; Rumbles, G.; Al-Jassim, M. M.
2007-01-01
The authors investigate the localization of photons emitted at the tip during scanning tunneling microscopy measurements on atomically flat gold substrates. Emission patterns of the plasmon-mediated luminescence exhibit distinct features that are assigned to the localized modes of the surface plasmon (LSP) confined to the tunneling gap and propagating modes (PSP) coupled to the LSP by the optical cavity beneath the tip. Tunneling luminescence spectroscopy reveals that the plasmon localization at the tip increases when modes of higher energy are excited. Acquisition of local emission patterns allows us for the simultaneous imaging of LSP and PSP modes.
Local-field excitations in two-dimensional lattices of resonant atoms
Volkov, S. N.; Kaplan, A. E. [Department of Electrical and Computer Engineering, Johns Hopkins University, Baltimore, Maryland 21218 (United States)
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.
Encoding the structure of many-body localization with matrix product operators
NASA Astrophysics Data System (ADS)
Pekker, David; Clark, Bryan K.
2015-03-01
Anderson insulators are non-interacting disordered systems which have localized single particle eigenstates. The interacting analogue of Anderson insulators are the Many-Body Localized (MBL) phases. The natural language for representing the spectrum of the Anderson insulator is that of product states over the single-particle modes. We show that product states over Matrix Product Operators of small bond dimension is the corresponding natural language for describing the MBL phases. In this language all of the many-body eigenstates are encode by Matrix Product States (i.e. DMRG wave function) consisting of only two sets of low bond-dimension matrices per site: the Gi matrix corresponding to the local ground state on site i and the Ei matrix corresponding to the local excited state. All 2 n eigenstates can be generated from all possible combinations of these matrices.
Tanimura, Katsumi; Inami, E.; Kanasaki, J.; Hess, Wayne P.
2006-07-16
We examine the mechanism of electronic bond rupture on semiconductor surfaces induced by laser-generated three-dimensional non-equilibrium valence excitation associated with strong carrier diffusion. For such excited systems, the density of sub-surface valence holes that contribute to two-hole localization on the surface is characterized by quasi Fermi level and effective temperature. The rate of two-hole localization, formulated for equilibrated two-dimensional electronic systems by Sumi [Surf. Sci, 248, 382 (1991)], is re-formulated, and a simple analytical expression is yielded for moderate excitation densities. The resulting theoretical model has been successfully applied in the analysis of recent laser-induced atomic desorption experiments on InP and Si surfaces
Tanimura, K.; Inami, E.; Kanasaki, J. [Institute of Scientific and Industrial Research, Osaka University, 8-1 Mihogaoka, Ibaraki, Osaka 567-0047 (Japan); Hess, Wayne P. [Pacific Northwest National Laboratory, Richland, Washington 99352 (United States)
2006-07-15
We examine the mechanism of electronic bond rupture on semiconductor surfaces induced by laser-generated nonequilibrium three-dimensional valence excitation associated with strong carrier diffusion. For such excited systems, the density of subsurface valence holes that contribute to two-hole localization on the surface is characterized by quasi-Fermi-levels and effective temperature. The rate of two-hole localization, formulated for equilibrated two-dimensional electronic systems by Sumi [Surf. Sci. 248, 382 (1991)], is reformulated, and a simple analytical expression is yielded for moderate excitation densities. The resulting theoretical model has been successfully applied in the analysis of recent laser-induced atomic desorption experiments on InP and Si surfaces.
NASA Astrophysics Data System (ADS)
Koehler, T. R.; Schmidt, J.
1980-10-01
We have studied the properties of naphthalene molecules in a durene host lattice by means of a computer calculation of the intermolecular interactions. The results support earlier experimental findings that the naphthalene molecule in its photo-excited triplet state reorients upon absorption of a quantum of a (pseudo)-localized phonon.
Kneipp, Katrin; Kneipp, Harald
2006-01-01
Surface-enhanced anti-Stokes Raman scattering from pumped excited vibrational levels and surface-enhanced hyper Raman scattering show a quadratic dependence on the excitation intensity and are discussed as incoherent two-photon excited Raman processes performed in strongly enhanced local optical fields of silver- or gold nanoclusters, where both effects can experience very similar electromagnetic enhancement conditions. PMID:16833105
Local calcium gradients during excitation–contraction coupling and alternans in atrial myocytes
Blatter, Lothar A; Kockskämper, Jens; Sheehan, Katherine A; Zima, Aleksey V; Hüser, Jörg; Lipsius, Stephen L
2003-01-01
Subcellular Ca2+ signalling during normal excitation-contraction (E-C) coupling and during Ca2+ alternans was studied in atrial myocytes using fast confocal microscopy and measurement of Ca2+ currents (ICa). Ca2+ alternans, a beat-to-beat alternation in the amplitude of the [Ca2+]i transient, causes electromechanical alternans, which has been implicated in the generation of cardiac fibrillation and sudden cardiac death. Cat atrial myocytes lack transverse tubules and contain sarcoplasmic reticulum (SR) of the junctional (j-SR) and non-junctional (nj-SR) types, both of which have ryanodine-receptor calcium release channels. During E-C coupling, Ca2+ entering through voltage-gated membrane Ca2+ channels (ICa) triggers Ca2+ release at discrete peripheral j-SR release sites. The discrete Ca2+ spark-like increases of [Ca2+]i then fuse into a peripheral ‘ring’ of elevated [Ca2+]i, followed by propagation (via calcium-induced Ca2+ release, CICR) to the cell centre, resulting in contraction. Interrupting ICa instantaneously terminates j-SR Ca2+ release, whereas nj-SR Ca2+ release continues. Increasing the stimulation frequency or inhibition of glycolysis elicits Ca2+ alternans. The spatiotemporal [Ca2+]i pattern during alternans shows marked subcellular heterogeneities including longitudinal and transverse gradients of [Ca2+]i and neighbouring subcellular regions alternating out of phase. Moreover, focal inhibition of glycolysis causes spatially restricted Ca2+ alternans, further emphasising the local character of this phenomenon. When two adjacent regions within a myocyte alternate out of phase, delayed propagating Ca2+ waves develop at their border. In conclusion, the results demonstrate that (1) during normal E-C coupling the atrial [Ca2+]i transient is the result of the spatiotemporal summation of Ca2+ release from individual release sites of the peripheral j-SR and the central nj-SR, activated in a centripetal fashion by CICR via ICa and Ca2+ release from j-SR, respectively, (2) Ca2+ alternans is caused by subcellular alterations of SR Ca2+ release mediated, at least in part, by local inhibition of energy metabolism, and (3) the generation of arrhythmogenic Ca2+ waves resulting from heterogeneities in subcellular Ca2+ alternans may constitute a novel mechanism for the development of cardiac dysrhythmias. PMID:12509476
Curchod, Basile F E; Penfold, Thomas J; Rothlisberger, Ursula; Tavernelli, Ivano
2015-07-20
The application of local control theory combined with nonadiabatic ab initio molecular dynamics to study the photoinduced intramolecular proton transfer reaction in 4-hydroxyacridine was investigated. All calculations were performed within the framework of linear-response time-dependent density functional theory. The computed pulses revealed important information about the underlying excited-state nuclear dynamics highlighting the involvement of collective vibrational modes that would normally be neglected in a study performed on model systems constrained to a subset of the full configuration space. This study emphasizes the strengths of local control theory for the design of pulses that can trigger chemical reactions associated with the population of a given molecular excited state. In addition, analysis of the generated pulses can help to shed new light on the photophysics and photochemistry of complex molecular systems. PMID:26036986
Sodt, Alex J.; Ratner, Mark A.
2010-01-01
We model the triplet-triplet energy transfer experiments from the Closs group [G. L. Closs et al, JACS, 110, p. 2652 (1988)] using a combination of Marcus theory and either Boys or Edmiston-Ruedenberg localized diabatization. We show that relative and absolute rates of electronic excitation transfer may be computed successfully, as we find ?calc = 2.8 per C-C bond, compared with the experimental value ?exp = 2.6, for the case where both donor and acceptor occupy equatorial positions on a rigid cyclohexane bridge. This work highlights the power of using localized diabatization methods as a tool for modeling non-equilibrium processes. PMID:20446743
Anderson transition for Google matrix eigenstates
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.
Describing excited state relaxation and localization in TiO2 nanoparticles using TD-DFT
Berardo, Enrico; Hu, Hanshi; van Dam, Hubertus JJ; Shevlin, S. A.; Woodley, Scott M.; Kowalski, Karol; Zwijnenburg, Martijn A.
2014-10-30
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. Finally, 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.
Ledermüller, Katrin; Schütz, Martin
2014-04-28
A multistate local CC2 response method for the calculation of analytic energy gradients with respect to nuclear displacements is presented for ground and electronically excited states. The gradient enables the search for equilibrium geometries of extended molecular systems. Laplace transform is used to partition the eigenvalue problem in order to obtain an effective singles eigenvalue problem and adaptive, state-specific local approximations. This leads to an approximation in the energy Lagrangian, which however is shown (by comparison with the corresponding gradient method without Laplace transform) to be of no concern for geometry optimizations. The accuracy of the local approximation is tested and the efficiency of the new code is demonstrated by application calculations devoted to a photocatalytic decarboxylation process of present interest. PMID:24784259
Ledermüller, Katrin; Schütz, Martin, E-mail: martin.schuetz@chemie.uni-regensburg.de [Institute of Physical and Theoretical Chemistry, University of Regensburg, Universitätsstraße 31, D-93040 Regensburg (Germany)] [Institute of Physical and Theoretical Chemistry, University of Regensburg, Universitätsstraße 31, D-93040 Regensburg (Germany)
2014-04-28
A multistate local CC2 response method for the calculation of analytic energy gradients with respect to nuclear displacements is presented for ground and electronically excited states. The gradient enables the search for equilibrium geometries of extended molecular systems. Laplace transform is used to partition the eigenvalue problem in order to obtain an effective singles eigenvalue problem and adaptive, state-specific local approximations. This leads to an approximation in the energy Lagrangian, which however is shown (by comparison with the corresponding gradient method without Laplace transform) to be of no concern for geometry optimizations. The accuracy of the local approximation is tested and the efficiency of the new code is demonstrated by application calculations devoted to a photocatalytic decarboxylation process of present interest.
Wang, Zhiqiang; Wen, Bo; Hao, Qunqing; Liu, Li-Min; Zhou, Chuanyao; Mao, Xinchun; Lang, Xiufeng; Yin, Wen-Jin; Dai, Dongxu; Selloni, Annabella; Yang, Xueming
2015-07-22
In reduced TiO2, electronic transitions originating from the Ti(3+)-induced states in the band gap are known to contribute to the photoabsorption, being in fact responsible for the material's blue color, but the excited states accessed by these transitions have not been characterized in detail. In this work we investigate the excited state electronic structure of the prototypical rutile TiO2(110) surface using two-photon photoemission spectroscopy (2PPE) and density functional theory (DFT) calculations. Using 2PPE, an excited resonant state derived from Ti(3+) species is identified at 2.5 ± 0.2 eV above the Fermi level (EF) on both the reduced and hydroxylated surfaces. DFT calculations reveal that this excited state is closely related to the gap state at ?1.0 eV below EF, as they both result from the Jahn-Teller induced splitting of the 3d orbitals of Ti(3+) ions in reduced TiO2. Localized excitation of Ti(3+) ions via 3d ? 3d transitions from the gap state to this empty resonant state significantly increases the TiO2 photoabsorption and extends the absorbance to the visible region, consistent with the observed enhancement of the visible light induced photocatalytic activity of TiO2 through Ti(3+) self-doping. Our work reveals the physical origin of the Ti(3+) related photoabsorption and visible light photocatalytic activity in prototypical TiO2 and also paves the way for the investigation of the electronic structure and photoabsorption of other metal oxides. PMID:26121118
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
NASA Astrophysics Data System (ADS)
Vincent, R.; Marinchio, H.; Sáenz, J. J.; Carminati, R.
2014-12-01
We investigate local control of the excitation of surface plasmon polaritons by a magnetic scatterer placed in the vicinity of a metallic surface. We show that under those conditions a change of about 27% in the surface plasmon intensity can be achieved by flipping the external magnetic field. The magnitude of this phenomenon is given by the magneto-optical Kerr effect (MOKE). A qualitative analysis of our numerical results, based on a perturbative approach, lead to simple analytical expressions for the longitudinal MOKE when the scatter is in close proximity to the surface. These results provide physical insight into the problem and may lead to the design of useful devices.
Bruno, D.; Colonna, G.; Laricchiuta, A. [CNR IMIP Bari, Bari (Italy); Capitelli, M. [CNR IMIP Bari, Bari (Italy); Department of Chemistry, University of Bari, Bari, Italy and CNR IMIP Bari, Bari (Italy)
2012-12-15
Internal and reactive contributions to the thermal conductivity of a local thermodynamic equilibrium nitrogen plasma have been calculated using the Chapman-Enskog method. Low-lying (LL) electronically excited states (i.e., states with the same principal quantum number of the ground state) and high-lying (HL) ones (i.e., states with principal quantum number n> 2) have been considered. Several models have been developed, the most accurate being a model that treats the LL states as separate species while disregarding the presence of HL states, on account of their enormous transport cross sections.
NASA Astrophysics Data System (ADS)
Bogdan, M. M.; Charkina, O. V.
2014-03-01
It is shown that the long-wave dynamics and magnetic properties of one-dimensional systems constructed of the inductively and capacitively coupled split-ring resonators are described by the regularized nonlinear dispersive Klein-Gordon equations. It is found that in such systems a high-frequency magnetic field excites dynamic solitons on a "pedestal"—stable breathers, oscillating in anti-phase with respect to the background of uniform oscillations, which means the existence of regions with a negative magnetic permeability in the system. If supplemented by a medium with negative permittivity, such a system forms a "left-handed" metamaterial in which the regions with the breather excitations are transparent to electromagnetic radiation. This makes it possible to observe them experimentally.
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.
Exact finite volume expectation values of local operators in excited states
B. Pozsgay; I. M. Szecsenyi; G. Takacs
2014-12-29
We present a conjecture for the exact expression of finite volume expectation values in excited states in integrable quantum field theories, which is an extension of an earlier conjecture to the case of general diagonal factorized scattering with bound states and a nontrivial bootstrap structure. The conjectured expression is a spectral expansion which uses the exact form factors and the excited state thermodynamic Bethe Ansatz as building blocks. The conjecture is proven for the case of the trace of the energy-moment tensor. Concerning its validity for more general operators, we provide numerical evidence using the truncated conformal space approach. It is found that the expansion fails to be well-defined for small values of the volume in cases when the singularity structure of the TBA equations undergoes a non-trivial rearrangement under some critical value of the volume. Despite these shortcomings, the conjectured expression is expected to be valid for all volumes for most of the excited states, and as an expansion above the critical volume for the rest.
Exact finite volume expectation values of local operators in excited states
NASA Astrophysics Data System (ADS)
Pozsgay, B.; Szécsényi, I. M.; Takács, G.
2015-04-01
We present a conjecture for the exact expression of finite volume expectation values in excited states in integrable quantum field theories, which is an extension of an earlier conjecture to the case of general diagonal factorized scattering with bound states and a nontrivial bootstrap structure. The conjectured expression is a spectral expansion which uses the exact form factors and the excited state thermodynamic Bethe Ansatz as building blocks. The conjecture is proven for the case of the trace of the energy-moment tensor. Concerning its validity for more general operators, we provide numerical evidence using the truncated conformal space approach. It is found that the expansion fails to be well-defined for small values of the volume in cases when the singularity structure of the TBA equations undergoes a non-trivial rearrangement under some critical value of the volume. Despite these shortcomings, the conjectured expression is expected to be valid for all volumes for most of the excited states, and as an expansion above the critical volume for the rest.
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).
Mukamel, Shaul
(fractal antenna macromolecules) are shown to be localized within segments connected by benzene rings transfer) as well as photochemical processes has been demonstrated to be strongly affected by geometric. It is difficult to anticipate this localization by inspecting the molecular orbitals since the system
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
Atomic mean excitation energies for stopping powers from local plasma oscillator strengths
NASA Technical Reports Server (NTRS)
Wilson, J. W.; Xu, Y. J.; Chang, C. K.; Kamaratos, E.
1984-01-01
The stopping of a charged particle by isolated atoms is investigated theoretically using an 'atomic plasma' model in which atomic oscillator strengths are replaced by the plasma frequency spectrum. The plasma-frequency correction factor for individual electron motion proposed by Pines (1953) is incorporated, and atomic mean excitation energies are calculated for atoms through Sr. The results are compared in a graph with those obtained theoretically by Inokuti et al. (1978, 1981) and Dehmer et al. (1975) and with the experimental values compiled by Seltzer and Berger (1982): good agreement is shown.
JOANNA E. ANDERSON CURRICULUM VITAE
of conflict discussions. Talk presented at the annual meeting of the Canadian Positive Psychology Association with low self-esteem derogate a partner's sacrifices. Talk presented at the annual meeting of the American1 JOANNA E. ANDERSON CURRICULUM VITAE Postdoctoral Fellow Department of Psychology Cornell
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.
LTP is accompanied by an enhanced local excitability of pyramidal neuron dendrites
Andreas Frick; Jeffrey Magee; Daniel Johnston
2004-01-01
The propagation and integration of signals in the dendrites of pyramidal neurons is regulated, in part, by the distribution and biophysical properties of voltage-gated ion channels. It is thus possible that any modification of these channels in a specific part of the dendritic tree might locally alter these signaling processes. Using dendritic and somatic whole-cell recordings, combined with calcium imaging
Constanza Rojas-Molina
2011-10-31
We study the Anderson metal-insulator transition for non ergodic random Schr\\"odinger operators in both annealed and quenched regimes, based on a dynamical approach of localization, improving known results for ergodic operators into this more general setting. In the procedure, we reformulate the Bootstrap Multiscale Analysis of Germinet and Klein to fit the non ergodic setting. We obtain uniform Wegner Estimates needed to perform this adapted Multiscale Analysis in the case of Delone-Anderson type potentials, that is, Anderson potentials modeling aperiodic solids, where the impurities lie on a Delone set rather than a lattice, yielding a break of ergodicity. As an application we study the Landau operator with a Delone-Anderson potential and show the existence of a mobility edge between regions of dynamical localization and dynamical delocalization.
Ekomasov, E G; Murtazin, R R; Ekomasov, A E; Dmitriev, S V
2013-01-01
We study properties of the localized solitons to the sine-Gordon equation excited on the attractive impurity by a moving kink. The cases of one- and two-dimensional spatially extended impurities are considered. For the case of one-dimensional impurity the possibility of excitation of the first even and odd high-amplitude impurity modes by the moving kink is demonstrated. For the case of two-dimensional impurity we show the possibility of excitation of the nonlinear high-amplitude waves of new type called here breathing pulson and breathing 2D soliton. We suggest different analytical expressions to model these nonlinear excitations. The dependencies of the oscillation frequency and the amplitude of the excited impurity modes on the impurity parameters are reported.
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.
Malakhovskii, A. V., E-mail: malakha@iph.krasn.ru [Russian Academy of Sciences, L. V. Kirensky Institute of Physics Siberian Branch (Russian Federation); Gnatchenko, S. L.; Kachur, I. S.; Piryatinskaya, V. G. [National Academy of Sciences of Ukraine, B. Verkin Institute for Low Temperature Physics and Engineering (Ukraine)] [National Academy of Sciences of Ukraine, B. Verkin Institute for Low Temperature Physics and Engineering (Ukraine); Sukhachev, A. L.; Sokolov, A. E.; Strokova, A. Ya.; Kartashev, A. V.; Temerov, V. L. [Russian Academy of Sciences, L. V. Kirensky Institute of Physics Siberian Branch (Russian Federation)] [Russian Academy of Sciences, L. V. Kirensky Institute of Physics Siberian Branch (Russian Federation)
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.
Zhongyuan Zhou; Shih-I Chu
The spin-dependent localized Hartree-Fock (SLHF) density-functional approach is extended to the treatment of the inner-shell excited-state calculation of open-shell atomic systems. In this approach, the electron spin-orbitals in an electronic configuration are obtained by solving Kohn-Sham (KS) equation with SLHF exchange potential and the Slater's diagonal sum rule is used to evaluate the multiplet energy of an inner-shell excited state
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
Powell, B J
2015-01-01
There is longstanding fundamental interest in 6-fold coordinated d(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
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.
ENHANCED WEGNER AND MINAMI ESTIMATES AND EIGENVALUE STATISTICS OF RANDOM ANDERSON MODELS
Boyer, Edmond
for the unfolded eigenvalues; · the local asymptotic ergodicity of the unfolded eigenvalues; In dimension 1, for the standard Anderson model, the improvement enables us to obtain the local spectral statistics at band edge distribution. [Kl10] used this re- duction to study the local ergodicity of the unfolded eigenvalues
Non-local dynamics of weakly nonlinear spin excitations in thin ferromagnetic films
NASA Astrophysics Data System (ADS)
Kiseliev, V. V.; Tankeyev, A. P.
1996-12-01
Effective integro-differential equations of weakly nonlinear dynamics describing the interaction of quasi-one-dimensional exchange-dipole spin-waves are derived for a thin ferromagnetic slab (film). The non-local part of the magnetostatic dispersion of these waves has been taken into account. Algebraic soliton-like states have been predicted. The conditions of their existence and their dynamic properties are investigated depending on the film thickness and on the magnitude and orientation of the external magnetic field. The role of crystallographic magnetic anisotropy in the formation of these states is analysed.
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
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.”
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.
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.
Spatially-antisymmetric localization of matter wave in a bichromatic optical lattice
NASA Astrophysics Data System (ADS)
Cheng, Y.; Adhikari, S. K.
2010-11-01
By direct numerical simulation of the time-dependent Gross-Pitaevskii equation using the split-step Fourier spectral method we study the double-humped localization of a cigar-shaped Bose-Einstein condensate (BEC) in a one-dimensional bichromatic quasi-periodic optical-lattice potential, as used in a recent experiment on the localization of a BEC [G. Roati et al., Nature 453, 895 (2008)]. Such states are spatially antisymmetric and are excited modes of Anderson localization. Where possible, we have compared the numerical results with a variational analysis. We also demonstrate the stability of the localized double-humped BEC states under small perturbation.
Phase Structure of the Topological Anderson Insulator
NASA Astrophysics Data System (ADS)
Xu, Dongwei; Sacksteder, Vincent E.; Qi, Junjie; Liu, Jie; Jiang, Hua; Xie, X. C.
2012-02-01
We report the phase structure of disordered HgTe topological Anderson insulator in a 2-D geometry. We use exact diagonalization to calculate the spectrum and eigenstate structure, and recursive green's functions to calculate the conductance. All observables are measured at several system sizes, allowing us to determine phase transitions and two critical points. The quantized-conductance TAI phase contains two phases: TAI-I lying in a bulk band gap, and TAI-II where bulk states exist but are localized. We find that the TAI-II phase persists at disorder strengths where there is no bulk band gap; a bulk band gap is not necessary to obtain conductance quantization. In a previous work the weak-disorder edge of the TAI phase was explained as a transition into the bulk gap (TAI-I), but we find also a direct transition into the ungapped (TAI-II) quantized phase. Effective medium theory (SCBA) predicts well the boundaries and interior of the TAI-I phase, but fails at larger disorders including the interior of the TAI-II phase. When the system size is smaller than the bulk localization length, the quantized TAI region is bounded by either the bulk band edge or the localization length, but when the system size is large it is bounded by a transition of edge states.
Zhongyuan Zhou; Shih-I. Chu
2005-01-01
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, electron spin orbitals in an electronic configuration are obtained first by solving the Kohn-Sham equation with an exact nonvariational spin-dependent localized Hartree-Fock exchange potential. Then a single-Slater-determinant
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...
Firth, Amy L.; Gordienko, Dmitri V.; Yuill, Kathryn H.; Smirnov, Sergey V.
2009-01-01
Mitochondria are proposed to be a major oxygen sensor in hypoxic pulmonary vasoconstriction (HPV), a unique response of the pulmonary circulation to low oxygen tension. Mitochondrial factors including reactive oxygen species, cytochrome c, ATP, and magnesium are potent modulators of voltage-gated K+ (Kv) channels in the plasmalemmal membrane of pulmonary arterial (PA) smooth muscle cells (PASMCs). Mitochondria have also been found close to the plasmalemmal membrane in rabbit main PA smooth muscle sections. Therefore, we hypothesized that differences in mitochondria localization in rat PASMCs and systemic mesenteric arterial smooth muscle cells (MASMCs) may contribute to the divergent oxygen sensitivity in the two different circulations. Cellular localization of mitochondria was compared with immunofluorescent labeling, and differences in functional coupling between mitochondria and Kv channels was evaluated with the patch-clamp technique and specific mitochondrial inhibitors antimycin A (acting at complex III of the mitochondrial electron transport chain) and oligomycin A (which inhibits the ATP synthase). It was found that mitochondria were located significantly closer to the plasmalemmal membrane in PASMCs compared with MASMCs. Consistent with these findings, the effects of the mitochondrial inhibitors on Kv current (IKv) were significantly more potent in PASMCs than in MASMCs. The cytoskeletal disruptor cytochalasin B (10 ?M) also altered mitochondrial distribution in PASMCs and significantly attenuated the effect of antimycin A on the voltage-dependent parameters of IKv. These findings suggest a greater structural and functional coupling between mitochondria and Kv channels specifically in PASMCs, which could contribute to the regulation of PA excitability in HPV. PMID:19098127
Two-dimensional Anderson-Hubbard model in the DMFT + {Sigma} approximation
Kuchinskii, E. Z., E-mail: kuchinsk@iep.uran.ru; Kuleeva, N. A.; Nekrasov, I. A.; Sadovskii, M. V., E-mail: sadovski@iep.uran.r [Russian Academy of Sciences, Institute for Electrophysics (Russian Federation)
2010-02-15
The density of states, the dynamic (optical) conductivity, and the phase diagram of the paramagnetic two-dimensional Anderson-Hubbard model with strong correlations and disorder are analyzed within the generalized dynamical mean field theory (DMFT + {Sigma} approximation). Strong correlations are accounted by the DMFT, while disorder is taken into account via the appropriate generalization of the self-consistent theory of localization. We consider the two-dimensional system with the rectangular 'bare' density of states (DOS). The DMFT effective single-impurity problem is solved by numerical renormalization group (NRG). The 'correlated metal,' Mott insulator, and correlated Anderson insulator phases are identified from the evolution of the density of states, optical conductivity, and localization length, demonstrating both Mott-Hubbard and Anderson metal-insulator transitions in two-dimensional systems of finite size, allowing us to construct the complete zero-temperature phase diagram of the paramagnetic Anderson-Hubbard model. The localization length in our approximation is practically independent of the strength of Hubbard correlations. But the divergence of the localization length in a finite-size two-dimensional system at small disorder signifies the existence of an effective Anderson transition.
DEAN P. ANDERSON Department of Zoology
Turner, Monica G.
, and J. Fryxell. 2005. Factors influencing female home-range sizes in elk (Cervus elaphus) in North American landscapes. Landscape Ecology 20:257-271. Anderson D.P. 2005. Preface: Reciprocal interactions the seasonality of estrus in Chimpanzees. Primates 47:43-50. Boesch, C., Z.B.G. Bi, D.P. Anderson, D. Stahl. 2005
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.
Topological approximation of the nonlinear Anderson model.
Milovanov, Alexander V; Iomin, Alexander
2014-06-01
We study the phenomena of Anderson localization in the presence of nonlinear interaction on a lattice. A class of nonlinear Schrödinger models with arbitrary power nonlinearity is analyzed. We conceive the various regimes of behavior, depending on the topology of resonance overlap in phase space, ranging from a fully developed chaos involving Lévy flights to pseudochaotic dynamics at the onset of delocalization. It is demonstrated that the quadratic nonlinearity plays a dynamically very distinguished role in that it is the only type of power nonlinearity permitting an abrupt localization-delocalization transition with unlimited spreading already at the delocalization border. We describe this localization-delocalization transition as a percolation transition on the infinite Cayley tree (Bethe lattice). It is found in the vicinity of the criticality that the spreading of the wave field is subdiffusive in the limit t?+?. The second moment of the associated probability distribution grows with time as a power law ? t^{?}, with the exponent ?=1/3 exactly. Also we find for superquadratic nonlinearity that the analog pseudochaotic regime at the edge of chaos is self-controlling in that it has feedback on the topology of the structure on which the transport processes concentrate. Then the system automatically (without tuning of parameters) develops its percolation point. We classify this type of behavior in terms of self-organized criticality dynamics in Hilbert space. For subquadratic nonlinearities, the behavior is shown to be sensitive to the details of definition of the nonlinear term. A transport model is proposed based on modified nonlinearity, using the idea of "stripes" propagating the wave process to large distances. Theoretical investigations, presented here, are the basis for consistency analysis of the different localization-delocalization patterns in systems with many coupled degrees of freedom in association with the asymptotic properties of the transport. PMID:25019865
Ground states and quasiparticle excitations of the Anderson lattice model
B. H. Brandow
1985-01-01
A variational method described previously has been extended to provide a simple and explicit realization of the Luttinger picture of a periodic Fermi liquid. The result can also be viewed as a renormalized band theory. This provides a general framework for understanding the electronic structure of periodic valence fluctuation systems.
Anderson and Kohn, page 1 Dikaryons, diploids, and evolution
Anderson, James B.
Anderson and Kohn, page 1 - Dikaryons, diploids, and evolution James B. Anderson and Linda M Kohn@utm.utoronto.ca #12;Anderson and Kohn, page 2 - The regular association of unfused, haploid, gametic- type nuclei genomes follow different rules, iii) #12;Anderson and Kohn, page 3 - dikaryons produce recombinant
Anderson transition in a three-dimensional kicked rotor.
Wang, Jiao; García-García, Antonio M
2009-03-01
We investigate Anderson localization in a three-dimensional (3D) kicked rotor. By a finite-size scaling analysis we identify a mobility edge for a certain value of the kicking strength k = k(c) . For k > k(c) dynamical localization does not occur, all eigenstates are delocalized and the spectral correlations are well described by Wigner-Dyson statistics. This can be understood by mapping the kicked rotor problem onto a 3D Anderson model (AM) where a band of metallic states exists for sufficiently weak disorder. Around the critical region k approximately k(c) we carry out a detailed study of the level statistics and quantum diffusion. In agreement with the predictions of the one parameter scaling theory (OPT) and with previous numerical simulations, the number variance is linear, level repulsion is still observed, and quantum diffusion is anomalous with
proportional t(2/3) . We note that in the 3D kicked rotor the dynamics is not random but deterministic. In order to estimate the differences between these two situations we have studied a 3D kicked rotor in which the kinetic term of the associated evolution matrix is random. A detailed numerical comparison shows that the differences between the two cases are relatively small. However in the deterministic case only a small set of irrational periods was used. A qualitative analysis of a much larger set suggests that deviations between the random and the deterministic kicked rotor can be important for certain choices of periods. Heuristically it is expected that localization effects will be weaker in a nonrandom potential since destructive interference will be less effective to arrest quantum diffusion. However we have found that certain choices of irrational periods enhance Anderson localization effects. PMID:19392034
Quantum localization without disorder in interacting Bose-Einstein condensates
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.
Zhou, Zhongyuan; Chu, Shih-I
2009-05-13
electron orbitals and kernel functions, and thus can be used to study the photoionization from atomic excited states. We have applied the approach to the calculation of photoionization cross sections of Ne ground state. The results are in agreement...
J.T. Anderson ,,10 Cusco, Peru
J.T. Anderson ,,10 Cusco, Peru In the summer of May 2010, I was honored to be given an opportunity in Peru. It is located near the Urubamba Valley of the Andes mountain range. Cusco has its historic roots
NASA Astrophysics Data System (ADS)
France, Kevin; Nell, Nicholas; Kane, Robert; Burgh, Eric B.; Beasley, Matthew; Green, James C.
2013-07-01
We present the first science results from the Sub-orbital Local Interstellar Cloud Experiment (SLICE): moderate resolution 1020-1070 Å spectroscopy of four sightlines through the local interstellar medium. High signal-to-noise (S/N) spectra of ? Uma, ? Vir, ? Sco, and ? 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 ? Sco and ? Oph. Our spectra indicate a factor of two lower total N(H2) than previously reported for ? Sco, which we attribute to higher S/N and better scattered light control in the new SLICE observations. We find N(H2) = 1.5 × 1019 cm-2 on the ? Sco sightline, with kinetic and excitation temperatures of 67 and 529 K, respectively, and a cloud density of n H = 56 cm-3. Our observations of the bulk of the molecular sightline toward ? Oph are consistent with previous measurements (N(H2) ? 3 × 1020 cm-2 at T 01(H2) = 66 K and T exc = 350 K). However, we detect significantly more rotationally excited H2 toward ? Oph than previously observed. We infer a cloud density in the rotationally excited component of n H ? 7600 cm-3 and suggest that the increased column densities of excited H2 are a result of the ongoing interaction between ? Oph and its environment; also manifest as the prominent mid-IR bowshock observed by WISE and the presence of vibrationally excited H2 molecules observed by the Hubble Space Telescope.
The Use of Digital Ink in Lecture Presentation Richard Anderson, Ruth Anderson!!!!, Crystal Hoyer,
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
Ryousuke Shiina
2005-01-01
A generalized periodic Anderson model with stable f2 configuration is examined through a Gutzwiller-type variational method (GM). In particular, we focus on the effect of the f2 crystal-field (CF) level scheme with singlet ground and triplet low-lying excited states. It is demonstrated that valence fluctuation from the f2 states is slightly enhanced by a small singlet--triplet CF splitting whereas it
Kosarim, A. V.; Smirnov, B. M. [Joint Institute for High Temperatures RAS, Moscow (Russian Federation); Laricchiuta, A. [CNR IMIP Bari, Bari (Italy); Capitelli, M. [CNR IMIP Bari, Bari (Italy); Department of Chemistry, University of Bari, Bari (Italy)
2012-06-15
The cross sections for charge-exchange and charge-transfer processes are evaluated for collisions of helium ions with parent-atoms in ground and excited states, with the principal quantum number n= 1-5, in the collision energy range from thermal up to 10 eV. Corresponding diffusion-type collision integrals are derived, and the role of 'abnormal' transport of electronically excited states on the reactive thermal conductivity of equilibrium helium plasma, at atmospheric pressure, estimated in the frame of a simplified approach.
Algebraic and geometric mean density of states in topological Anderson insulators
NASA Astrophysics Data System (ADS)
Zhang, Yan-Yang; Shen, Shun-Qing
2013-11-01
Algebraic and geometric mean density of states in disordered systems may reveal properties of electronic localization. In order to understand the topological phases with disorder in two dimensions, we present the calculated density of states for the disordered Bernevig-Hughes-Zhang model. The topological phase is characterized by a perfectly quantized conducting plateau, carried by helical edge states, in a two-terminal setup. In the presence of disorder, the bulk of the topological phase is either a band insulator or an Anderson insulator. Both of them can protect edge states from backscattering. The topological phases are explicitly distinguished as a topological band insulator or a topological Anderson insulator from the ratio of the algebraic mean density of states to the geometric mean density of states. The calculation reveals that the topological Anderson insulator can be induced by disorders from either a topologically trivial band insulator or a topologically nontrivial band insulator.
Aakre Caitlyn Elementary Education Anderson Courtney Elementary Education
Maxwell, Bruce D.
EDUCATION Aakre Caitlyn Elementary Education Anderson Courtney Elementary Education Anderson Sarah Elementary Education Bailey Molly Elementary Education Barber Elizabeth Elementary Education Bechtold Ryan Elementary Education Bigelow Katrina Elementary Education Bigelow Katrina Elementary Education Bradford
K. Birgitta Whaley
2008-01-01
Planar aromatic molecules provide strongly localizing potentials for helium that considerably modify the local superfluid properties of a solvating helium environment. I shall describe some of the effects of these interactions on the solvation structure and spectroscopy of tetracene and phthalocyanine in helium droplets, comparing results of zero and finite temperature quantum Monte Carlo simulations with experimental data. The helium
Ding, L J; Yao, K L; Fu, H H
2011-01-01
The zero- and low-temperature behaviors of a quasi-one-dimensional organic polymer proposed as a symmetrical periodic Anderson-like chain model, in which the localized f orbitals hybridize with the conduction orbitals at even sites, are investigated by means of many-body Green's function theory. In the absence of magnetic field, the ground state of the system turns out to be ferrimagnetic. The temperature-induced phase diagrams have been explored, where the competition between the Hubbard repulsion U on the localized f orbital and the hybridization strength V makes an important impact on the transition temperature. In a magnetic field, it is found that a 1/3 magnetization plateau appears and two critical fields indicating the insulator-metal transitions at zero temperature emerge, which are closely related to the energy bands. Furthermore, the single-site entanglement entropy is a good indicator of quantum phase transitions. The temperature-field-induced phase diagram has also been attained, wherein the magnetization plateau state, the gapless phase and the spin polarized state are revealed. The temperature dependence of thermodynamic quantities such as the magnetization, susceptibility and specific heat are calculated to characterize the corresponding phases. It is also found that the up-spin and down-spin hole excitations are responsible for the thermodynamic properties. PMID:21031205
Topology, delocalization via average symmetry and the symplectic Anderson transition.
Fu, Liang; Kane, C L
2012-12-14
A field theory of the Anderson transition in two-dimensional disordered systems with spin-orbit interactions and time-reversal symmetry is developed, in which the proliferation of vortexlike topological defects is essential for localization. The sign of vortex fugacity determines the Z(2) topological class of the localized phase. There are two distinct fixed points with the same critical exponents, corresponding to transitions from a metal to an insulator and a topological insulator, respectively. The critical conductivity and correlation length exponent of these transitions are computed in an N=1-[symbol: see text] expansion in the number of replicas, where for small [symbol: see text] the critical points are perturbatively connected to the Kosterlitz-Thouless critical point. Delocalized states, which arise at the surface of weak topological insulators and topological crystalline insulators, occur because vortex proliferation is forbidden due to the presence of symmetries that are violated by disorder, but are restored by disorder averaging. PMID:23368359
UNIONE MATEMATICA ITALIANA David F. Anderson, Ayman Badawi, David E.
Badawi, Ayman
BOLLETTINO UNIONE MATEMATICA ITALIANA David F. Anderson, Ayman Badawi, David E. Dobbs Pseudo. ANDERSON - AYMAN BADAWI - DAVID E. DOBBS Sunto. Viene data una condizione sufficiente affinchè un sopra #12;DAVID F. ANDERSON - AYMAN BADAWI - DAVID E. DOBBS536 of R if R%B%T; if I is an ideal of R, then (I
INET 2000 Anderson, Camp The Telecom Road Less Traveled
Camp, L. Jean
1 INET 2000 Anderson, Camp The Telecom Road Less Traveled Brian L. Anderson brian · Efficacy of poverty alleviation programs #12;2 INET 2000 Anderson, Camp The Road Less Chosen · Bangladesh As a Nation · 1,800 miles of railway · 8,500 miles of road In comparison Wisconsin has 110,000 · Per capita
Nikiforov, Maxim [ORNL
2008-01-01
An approach for thermomechanical characterization of phase transitions in polymeric materials (PET) by band excitation acoustic force microscopy is developed. This methodology allows the independent measurement of resonance frequency, Q factor, and oscillation amplitude as a function of temperature of a small volume, from which the thermal evolution of tip-surface spring constant and mechanical dissipation can be extracted. We demonstrate a heating protocol which keeps the contact area and contact force constant, thus allowing for reproducible measurements and quantitative extraction of materials properties including temperature dependence of indentation-based elastic and loss moduli. PACS: 82.35.Lr + 82.35.Jk + 68.37.Ps
Chiral Condensate and Mott-Anderson Freeze-Out
NASA Astrophysics Data System (ADS)
Blaschke, D.; Berdermann, J.; Cleymans, J.; Redlich, K.
2012-07-01
We present the idea of a Mott-Anderson freeze-out that suggests a key role of the localization of the hadron wave functions when traversing the hadronization transition. The extension of hadron wave functions in dense matter is governed by the behavior of the chiral quark condensate such that its melting at finite temperatures and chemical potentials entails an increase of the size of hadrons and thus their geometrical strong interaction cross sections. It is demonstrated within a schematic resonance gas model, that a kinetic freeze-out condition reveals a correlation with the reduction of the chiral condensate in the phase diagram up to 50% of its vacuum value. Generalizing the description of the chiral condensate by taking into account a full hadron resonance gas such correlation gets distorted. We discuss, that this may be due to our approximations in calculating the chiral condensate which disregard both, in-medium effects on hadron masses and hadron-hadron interactions. The latter, in particular due to quark exchange reactions, could lead to a delocalization of the hadron wave functions in accordance with the picture of a Mott-Anderson transition.
Administration Noma Bennett Anderson, PhD
Cui, Yan
Administration Dean Noma Bennett Anderson, PhD Assistant Deans Faculty and Academic Affairs RebeccaD Department of Physical Therapy Chair and Program Director CarolCountLikens,PT,PhD,MBA Department of Physician Assistant Studies Chair & Director Johnna Tanner, MSPAS, PA
The Anderson Model as a matrix model
J. Magnen; G. Poirot; V. Rivasseau
1997-01-01
In this paper we describe a strategy to study the Anderson model of an electron in a random potential at weak coupling by a renormalization group analysis. There is an interesting technical analogy between this problem and the theory of random matrices. In d = 2 the random matrices which appear are approximately of the free type well known to
Biology Office Shauna C. Anderson, Director
Hart, Gus
Biology Biology Office Shauna C. Anderson, Director 375 WIDB, (801) 422-4295 College of Biology program in biology has open enrollment. The Discipline A degree for students who desire a broad approach to biology, the major provides solid preparation for graduate schools in most fields of biology as well
California's Snow Zone Lands Henry W. Anderson
Standiford, Richard B.
. . . . . . . . . . . . . . . . . . . . . . . . 13 Water Losses in Winter and Spring . . . . . . . . . . . . . . . . . . . . . . 13 Water Losses . . . . . . . . . . . . . . . . . . . . . . . . . 15 Water Savings in Summer . . . . . . . . . . . . . . . . . . . . . . . . . . 15 Water LossesManaging California's Snow Zone Lands for Water Henry W. Anderson U S . F O R E S T S E R V I C E R
Fabian Pena; Shawn Kridler; Pete Berger
2008-01-01
The authors will demonstrate how to use a bed of nails to pump up the students at local K-12 schools. The use during Science Road Show presentations will be addressed along with suggestions on how to build the drama and introduce humor and learning.
NASA Astrophysics Data System (ADS)
Pena, Fabian; Kridler, Shawn; Berger, Pete
2008-03-01
The authors will demonstrate how to use a bed of nails to pump up the students at local K-12 schools. The use during Science Road Show presentations will be addressed along with suggestions on how to build the drama and introduce humor and learning.
Jensen, Max
Placement, near to Durham Three aspects of the life of St Mary Magdalene church in Belmont, Durham stand out of the church to provide for the social and recreational needs of the entire local community. St Mary Magdalene is not straightforward! So the ostentatious opulence of the haute coûture fashion houses of la rue Faubourg Saint Honoré
NASA Astrophysics Data System (ADS)
Bozzano, F.; Lenti, L.; Martino, S.; Paciello, A.; Scarascia Mugnozza, G.
2008-10-01
An integrated numerical and geophysical approach was used to investigate the role of local seismic amplification in the reactivation of the Salcito landslide (Italy) after the Molise earthquake of 31 October 2002. Numerical stress-strain analysis with FLAC 5.0 FDM software, performed in dynamic configuration, showed that the 1 Hz frequency was consistent with landslide instability conditions. The Fourier spectrum of the triggering earthquake showed two main peaks occurring at 1 and 2 Hz, respectively, which could be related to local effects. The analysis of H/V spectral ratios of ambient noise records obtained in the landslide area, evidenced amplification effects in the 1-3 Hz range. On the basis of an engineering geology model, numerical modeling of both 1-D and 2-D seismic wave propagation was conducted using linear and nonlinear solutions. The simulation outputs showed (1) a 1 Hz amplification ascribable to 2-D effects due to a landslide mass lying within a basin-like geological structure; (2) a double-peak amplification at about 2 and 3 Hz, respectively, ascribable to 1-D resonance of the landslide mass; and (3) 1-D plus lateral wave effects within the landslide mass in the 2.5-3.5 Hz frequency range. These findings suggest that local amplification of ground motion by the Salcito landslide mass may generate a self-excitation process responsible for its reactivation.
L. Oster; Y. S. Horowitz; S. Biderman; Y. Fuks; Y. Belaish; D. Sattinger
2007-01-01
It is shown that glow peak 5a (a low-temperature satellite of the major glow peak 5) arises from localized electron–hole recombination in a trapping center (TC)–luminescent center (LC) pair believed to be based on Mg2+ –Livac trimers (the TCs) coupled to Ti(OH)n molecules (the LCs). Peak 5 arises from the same complex which has captured an electron only , and
Tarrab-Hazdai, R; Geiger, B; Fuchs, S; Amsterdam, A
1978-01-01
Nicotinic acetylcholine receptor was localized in a receptor-rich membrane preparation from the electric organ of Torpedo californica by applying an immunoferritin technique. The membrane preparation was incubated with (Fab')2 fragments derived from specific rabbit antibodies against the purified acetylcholine receptor and subsequently with ferritin-conjugated goat antiserum to rabbit immunoglobulin. More than 50% of the vesicles were found to be labeled with ferritin while the rest remained unlabeled. Ferritin labeling on both sides of the membrane was evident in open membrane vesicles, whereas in closed vescles the labeling was confined to the outer surface due to the inability of the tracer to penetrate the membrane. These data suggest that antigenic sites of the receptor molecule are exposed on both sides of the excitable membrane, and that acetylcholine receptor may be a transmembrane protein. Images PMID:276886
Energy level statistics in disordered metals with an Anderson transition
Evangelou, S.N. [Univ. of Ioannina (Greece)]|[Institute for Electronic Structure & Lasers, Crete (Greece); Katsanos, D.E. [Univ. of Ioannina (Greece)
1996-12-01
We present numerical scaling results for the energy level statistics in orthogonal and symplectic tight-binding Hamiltonian random matrix ensembles defined on disordered two and three-dimensional electronic systems with and without spin-orbit coupling (SOC), respectively. In the metallic phase for weak disorder the nearest level spacing distribution function P(S), the number variance <({delta}N){sup 2}>, and the two-point correlation function K{sub 2}({epsilon}) are shown to be described by the Gaussian random matrix theories. In the insulating phase, for strong disorder, the correlations vanish for large scales and the ordinary Poisson statistics is asymptotically recovered, which is consistent with localization of the corresponding eigenstates. At the Anderson metal-insulator transition we obtain new universal scale-invariant distribution functions describing the critical spectral density fluctuations.
Price-Anderson Act: Congressional review begins
Not Available
1984-07-05
Every 10 years Congress reviews, amends, and extends the Price-Anderson Act of 1957, which was designed to encourage the new nuclear industry by guaranteeing insurance beyond the level provided by private insurers. The Nuclear Regulatory Commission is recommending five congressional actions for the 1987 extension: reauthorization, replacement of the absolute insurance limitation with an annual limitation of liability, raising the retrospective premium per reactor per incident from $5 million to $10 million, raising the statute of limitations on claims for 20 to 30 years, and retaining current language dealing with extraordinary events. Two bills, H.R. 421 and H.R. 3277, were introduced with provisions that broaden the opportunity for victims compensation and eliminate the subsidy aspect. Hearings began in July, with reactions from the National Taxpayers Union and Nuclear insurance underwriters in conflict over the limitations on liability. DOE and DOE contractors urge continuation of the Price-Anderson limitation.
Laparoscopic Anderson-Hynes pyeloplasty in children
F. Schier
1998-01-01
In two children (ages 14 and 7 years) a laparoscopic Anderson-Hynes pyeloplasty was performed. In the 14-year-old boy a para-anastomotic\\u000a drain was placed; a urinoma developed postoperatively, which was treated by a pyelostoma placed transcutaneously. In the 7-year-old\\u000a boy a transanastomotic pyelostoma splint was placed intraoperatively. The splint was removed 10?days later; the postoperative\\u000a course was uneventful. Operative time was
On Mott's formula for the ac-conductivity in the Anderson model
Abel Klein; Olivier Lenoble; Peter M
2006-01-01
We study the ac-conductivity in linear response theory in the general framework of ergodic magnetic Schrodinger operators. For the Anderson model, if the Fermi energy lies in the localization regime, we prove that the ac-conductivity is bounded by C?2(log 1 ?) d+2 at small frequencies ?. This is to be compared to Mott's formula, which predicts the leading term to
Ground state properties of the two-band Anderson-type model in one dimension
H. Kaga; T. Fujiwara
1986-01-01
We study the ground states of the one-dimensional two-band Anderson type model in both the symmetric and the asymmetric cases. In the symmetric case the analytical expression of the charge-complex distribution function is formally derived, which is then applied to calculate the binding energy of the Kondo state. In the general asymmetric cases the behaviors of localized- and conduction-electron numbers
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.
Magnetic field induced quantum phase transitions in the two-impurity Anderson model
Zhu, Lujun [Los Alamos National Laboratory; Zhu, Jian - Xin [Los Alamos National Laboratory
2010-11-17
In the two-impurity Anderson model, the inter-impurity spin exchange interaction favors a spin singlet state between two impurities leading to the localization of quasiparticles. We show that a local uniform magnetic field can delocalize the quasiparticies to restore the Kondo resonance. This transition is found to be continuous, accompanied by not only the divergence of the staggered (anti ferromagnetic) susceptibility, but also the divergence of the uniform spin susceptibility. This implies that the magnetic field induced quantum phase transitions in Kondo systems are in favor of the local critical type.
Gálisová, Lucia; Stre?ka, Jozef
2015-02-01
A hybrid spin-electron system defined on a one-dimensional double-tetrahedral chain, in which the localized Ising spin regularly alternates with two mobile electrons delocalized over a triangular plaquette, is exactly solved with the help of generalized decoration-iteration transformation. It is shown that a macroscopic degeneracy of ferromagnetic and ferrimagnetic ground states arising from chiral degrees of freedom of the mobile electrons cannot be lifted by a magnetic field in contrast to a macroscopic degeneracy of the frustrated ground state, which appears due to a kinetically driven frustration of the localized Ising spins. An anomalous behavior of all basic thermodynamic quantities can be observed on account of massive thermal excitations, which mimic a temperature-driven first-order phase transition from the nondegenerate frustrated state to the highly degenerate ferrimagnetic state at nonzero magnetic fields. A substantial difference in the respective degeneracies is responsible for an immense low-temperature peak of the specific heat and very abrupt (almost discontinuous) thermal variations of the entropy and sublattice magnetizations. PMID:25768485
NASA Astrophysics Data System (ADS)
Gálisová, Lucia; Stre?ka, Jozef
2015-02-01
A hybrid spin-electron system defined on a one-dimensional double-tetrahedral chain, in which the localized Ising spin regularly alternates with two mobile electrons delocalized over a triangular plaquette, is exactly solved with the help of generalized decoration-iteration transformation. It is shown that a macroscopic degeneracy of ferromagnetic and ferrimagnetic ground states arising from chiral degrees of freedom of the mobile electrons cannot be lifted by a magnetic field in contrast to a macroscopic degeneracy of the frustrated ground state, which appears due to a kinetically driven frustration of the localized Ising spins. An anomalous behavior of all basic thermodynamic quantities can be observed on account of massive thermal excitations, which mimic a temperature-driven first-order phase transition from the nondegenerate frustrated state to the highly degenerate ferrimagnetic state at nonzero magnetic fields. A substantial difference in the respective degeneracies is responsible for an immense low-temperature peak of the specific heat and very abrupt (almost discontinuous) thermal variations of the entropy and sublattice magnetizations.
Giovannini, L.; Montoncello, F.; Nizzoli, F.; Vavassori, P.; Grimsditch, M. (Materials Science Division); (Dipartimento di Fisica); (CNISM); (Basque Foundation for Science)
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).
Percolating states in the topological Anderson insulator
NASA Astrophysics Data System (ADS)
Girschik, Adrian; Libisch, Florian; Rotter, Stefan
2015-06-01
We investigate the presence of percolating states in disordered two-dimensional topological insulators. In particular, we uncover a close connection between these states and the so-called topological Anderson insulator, which is a topologically nontrivial phase induced by the presence of disorder. The decay of this phase could previously be connected to a delocalization of bulk states with increasing disorder strength. We identify this delocalization to be the result of a percolation transition of states that circumnavigate the hills of the bulk disorder potential.
Bray, James William (Niskayuna, NY); Garces, Luis Jose (Niskayuna, NY)
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.
SEAL A SIMPLE ENTITY ANNOTATION LANGUAGE Eike F Anderson
Davies, Christopher
SEAL A SIMPLE ENTITY ANNOTATION LANGUAGE Eike F Anderson The National Centre for Computer introduce the simple entity annotation language SEAL, a fully working subset of the AvDL behaviour definition language introduced by [Anderson 2005]. SEAL presents a simple scripting solution for embedding
Phase diagram for Anderson disorder: Beyond single-parameter scaling
Nigel Goldenfeld; Roger Haydock
2006-01-01
The Anderson model for independent electrons in a disordered potential is transformed analytically and exactly to a basis of random extended states leading to a variant of augmented space. In addition to the widely accepted phase diagrams in all physical dimensions, a plethora of additional, weaker Anderson transitions are found, characterized by the long-distance behavior of states. Critical disorders are
Carl Anderson, former Biol-ogy Department Chair, has been
Ohta, Shigemi
the Bulletin Carl Anderson, former Biol- ogy Department Chair, has been named Senior Scientist pathways in cancerous cells to stop them from growing and... See Carl Anderson on p. 2 Vol. 65 - No. 30 August 26, 2011 RogerStoutenburghD1400810CourtesyofCornellUniversity RogerStoutenburghD2260605 Roger
Participant List and Biographies Cheryl Anderson, canderso@hawaii.edu
Colorado at Boulder, University of
- 92 - APPENDIX A Participant List and Biographies Cheryl Anderson, canderso@hawaii.edu Social Science Research Institute, University of Hawai`i C heryl L. Anderson is a certified planner (AICP), doctoral candidate, and the Director of the Hazards, Climate, and Environment Program, University of Hawai`i
Critical State of the Anderson Transition: Between a Metal and an Insulator
Lemarie, Gabriel; Delande, Dominique [Laboratoire Kastler Brossel, UPMC-Paris 6, ENS, CNRS, 4 Place Jussieu, F-75005 Paris (France); Lignier, Hans; Szriftgiser, Pascal; Garreau, Jean Claude [Laboratoire de Physique des Lasers, Atomes et Molecules, Universite Lille 1 Sciences et Technologies, UMR CNRS 8523, F-59655 Villeneuve d'Ascq Cedex (France)
2010-08-27
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 wave packet 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 the self-consistent theory of localization.
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…
Critical charge fluctuations in a pseudogap Anderson model
NASA Astrophysics Data System (ADS)
Chowdhury, Tathagata; Ingersent, Kevin
2015-01-01
The Anderson impurity model with a density of states ? (? ) ?|?| r containing a power-law pseudogap centered on the Fermi energy (? =0 ) features for 0
The Anderson Reservoir seismic gap - Induced aseismicity?
Bufe, C.G.
1976-01-01
A persistent 10-km seismicity gap along the Calaveras fault appears to be related to the presence of the Leroy Anderson Reservoir in the Calaveras-Silver Creek fault zones southeast of San Jose, California. A magnitude-4.7 earthquake occurred at a depth of 5 km in the centre of the gap on October 3, 1973. The sequence of immediate aftershocks usually accompanying shallow earthquakes of this magnitude in central California did not occur. A bridge crossing the reservoir near its southeast end has been severely deformed, apparently the result of tectonic creep on the Calaveras fault. The occurrence of creep and absence of small earthquakes along the Calaveras in the vicinity of the reservoir suggest a transition from stick slip to stable sliding, possibly brought about by increased pore pressure. ?? 1976.
Anderson metal-insulator transitions with classical magnetic impurities
NASA Astrophysics Data System (ADS)
Jung, Daniel; Kettemann, Stefan
2014-08-01
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 Wc, in the presence of Heisenberg impurities, Wc 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].
Anderson metal-insulator transitions with classical magnetic impurities
Jung, Daniel [School of Engineering and Science, Jacobs University Bremen gGmbH, Campus Ring 1, 28759 Bremen, Germany and Division of Advanced Materials Science, Pohang University of Science and Technology (POSTECH), San 31, Hyoja-dong, Nam-gu, Pohang 790-784 (Korea, Republic of); Kettemann, Stefan [School of Engineering and Science, Jacobs University Bremen gGmbH,Campus Ring 1, 28759 Bremen, Germany and Division of Advanced Materials Science, Pohang University of Science and Technology (POSTECH), San 31, Hyoja-dong, Nam-gu, Pohang 790-784 (Korea, Republic of)
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].
Attosecond Photoscopy of Plasmonic Excitations
NASA Astrophysics Data System (ADS)
Lupetti, Mattia; Hengster, Julia; Uphues, Thorsten; Scrinzi, Armin
2014-09-01
We propose an experimental arrangement to image, with attosecond resolution, transient surface plasmonic excitations. The required modifications to state-of-the-art setups used for attosecond streaking experiments from solid surfaces only involve available technology. Buildup and lifetimes of surface plasmon polaritons can be extracted and local modulations of the exciting optical pulse can be diagnosed in situ.
Foundations of Physics, Vol . 28, No. 4, 1998 Bands of Localized Electromagnetic Waves in
Rusek, Marian
methods and concepts of solid-state physics. Let us mention, e.g., the concept of electron localization in investigations of Anderson localization in solid-state physics is to study the transport equa- tion
Anderson, Tom
, authentication, and security. On a single machine, appli cation developers can rely on the local operating scalable, and dy namically reconfigurable. Experience with a number of ap plications developed under Web Microsystems, Cal ifornia MICRO, Novell, Hewlett Packard, Intel, Microsoft, and Mit subishi. Anderson
Dahlin, Michael D.
, and security. On a single machine, application developers can rely on the local operating system to provide that are geographically distributed, highly available, incrementally scalable, and dynamically reconfiguring. Experience MICRO, Novell, Hewlett Packard, Intel, Microsoft, and Mitsubishi. Anderson was also supported
Localization for random perturbations of anisotropic periodic media
Peter Stollmann; Fachbereich Mathematik; Johann Wolfgang Goethe-Universitiit
1998-01-01
We prove localization for random perturbations of periodic divergence form operators of the form ? · a? · ? near the band edges. Here a? is a matrix function which results from an Anderson type perturbation of a periodic matrix function.
Entanglement of localized states
Giraud, O.; Martin, J.; Georgeot, B. [Laboratoire de Physique Theorique, Universite Toulouse III, CNRS, 31062 Toulouse (France)
2007-10-15
We derive exact expressions for the mean value of Meyer-Wallach entanglement Q for localized random vectors drawn from various ensembles corresponding to different physical situations. For vectors localized on a randomly chosen subset of the basis, tends for large system sizes to a constant which depends on the participation ratio, whereas for vectors localized on adjacent basis states it goes to zero as a constant over the number of qubits. Applications to many-body systems and Anderson localization are discussed.
Fractal Superconductivity near Localization Threshold
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
Charge localization and transport in disordered dielectric materials
Guy Blaise
2001-01-01
The effect of disorder in solid insulators (ceramics and polymers) is to produce localized states (Anderson) from which results the localization of charge. To account for the conduction properties of these materials, the description of localized states in the conduction band tail is based on the Mott's formalism. The mobility edge Ec between localized and extended states is located in
Federal Register 2010, 2011, 2012, 2013, 2014
2010-06-16
...TA-W-73,230A] Plastic Omnium Automotive Exteriors, LLC, Anderson, SC; Plastic Omnium Automotive Exteriors, LLC, Troy, MI; Amended...applicable to workers of Plastic Omnium Automotive Exteriors, LLC, Anderson, South...
Investigation of Anderson lattice behavior in Yb1-xLuxAl3
Bauer, E.D.; Booth, C.H.; Lawrence, J.M.; Hundley, M.F.; Sarrao, J.L.; Thompson, J.D.; Riseborough, P.S.; Ebihara, T.
2003-10-06
Measurements of magnetic susceptibility {chi}(T), specific heat C(T), Hall coefficient R{sub H}(T), and Yb valence {nu} = 2 + n{sub f} [f-occupation number n{sub f} (T) determined from Yb L{sub 3} x-ray absorption measurements] were carried out on single crystals of Yb{sub 1-x}Lu{sub x}Al{sub 3}. The low temperature anomalies observed in {chi}(T) and C(T) corresponding to an energy scale T{sub coh} {approx} 40 K in the intermediate valence, Kondo lattice compound YbAl{sub 3} are suppressed by Lu concentrations as small as 5% suggesting these low-T anomalies are extremely sensitive to disorder and, therefore, are a true coherence effect. By comparing the temperature dependence of various physical quantities to the predictions of the Anderson Impurity Model, the slow crossover behavior observed in YbAl{sub 3}, in which the data evolve from a low-temperature coherent, Fermi-liquid regime to a high temperature local moment regime more gradually than predicted by the Anderson Impurity Model, appears to evolve to fast crossover behavior at x {approx} 0.7 where the evolution is more rapid than predicted. These two phenomena found in Yb{sub 1-x}Lu{sub x}Al{sub 3}, i.e., the low-T anomalies and the slow/fast crossover behavior are discussed in relation to recent theories of the Anderson lattice.
Quantum critical phase and Lifshitz transition in an extended periodic Anderson model.
Laad, M S; Koley, S; Taraphder, A
2012-06-13
We study the quantum phase transition in f-electron systems as a quantum Lifshitz transition driven by selective-Mott localization in a realistic extended Anderson lattice model. Using dynamical mean-field theory (DMFT), we find that a quantum critical phase with anomalous ?/T scaling separates a heavy Landau-Fermi liquid from ordered phase(s). This non-Fermi liquid state arises from a lattice orthogonality catastrophe originating from orbital-selective Mott localization. Fermi surface reconstruction occurs via the interplay between and penetration of the Green function zeros to the poles, leading to violation of Luttinger's theorem in the strange metal. We show how this naturally leads to scale-invariant responses in transport. Thus, our work represents a specific DMFT realization of the hidden-FL and FL* theories, and holds promise for the study of 'strange' metal phases in quantum matter. PMID:22589244
ANDERSON ACCELERATION FOR FIXED-POINT ITERATIONS HOMER F. WALKER AND PENG NI
Walker, Homer F.
ANDERSON ACCELERATION FOR FIXED-POINT ITERATIONS HOMER F. WALKER AND PENG NI Abstract. This paper concerns an acceleration method for fixed-point iterations that originated in work of D. G. Anderson-560], which we accordingly call Anderson acceleration here. This method has enjoyed considerable success
Observations of nighttime winds using pilot balloons in Anderson Creek Valley, Geysers, California
Nappo, C.J.; Snodgrass, H.F.
1981-06-01
Nighttime drainage or downslope winds along the east-facing slope of Anderson Creek Valley located in the Geysers area of northern California are examined using pilot balloons as air parcel tracers. Observations made over four nights show a persistent pattern of winds. Before sunset strong westerly winds blow into the valley. These winds are believed due to the late afternoon sea breeze. Drainage winds become fully developed within 2 h after sunset. The drainage wind has an average speed of approx.3 m s/sup -1/ regardless of the speed of the ambient wind. The drainage layer thickness grows at a rate of approx.80 m per kilometer of downwind distance. Balloons in the drainage current quickly spread throughout the shallow, sidewall canyon containing Anderson Creek. The transition from the local valley wind system to the free, ambient wind occurs at about ridge height, i.e., /sub 5/00 m above the valley basin, for weak ambient winds, and at /sub 3/00 m above the valley basin for strong ambient winds.
On one-step replica symmetry breaking in the Edwards-Anderson spin glass model
Del Ferraro, Gino; Zhou, Hai-Jun; Aurell, Erik
2015-01-01
We consider a one-step replica symmetry breaking description of the Edwards-Anderson spin glass model in 2D. The ingredients of this description are a Kikuchi approximation to the free energy and a second-level statistical model built on the extremal points of the Kikuchi approximation, which are also fixed points of a Generalized Belief Propagation (GBP) scheme. We show that a generalized free energy can be constructed where these extremal points are exponentially weighted by their Kikuchi free energy and a Parisi parameter y, and that the Kikuchi approximation of this generalized free energy leads to second-level, one-step replica symmetry breaking, GBP equations. We then show that contrary to the analogous case of Bethe approximations in locally tree-like graphs this second-level GBP does not have a class of simpler solutions analogous to Survey Propagation. We attribute this discrepancy to the presence of short loops in a region graph description of the Edwards-Anderson model, and argue that it should be ...
Excitation Transport and Electrical Conductivity in Disordered Media.
NASA Astrophysics Data System (ADS)
Franchi, Daniel S.
The investigation of the incoherent/localization transition of excitations in classical and quantum systems has become a popular area of study. The location of the transition and the behavior around the transition, for example the critical exponents are candidates for universal properties when a percolation model is considered. Some of the existing methods to understand the transitions will be described and the quantities of interest will be defined. This includes the electrical conductivity which will be related by linear response theory to the diffusion for a percolation type model of excitons. I then examine two procedures developed by Loring, Mukamel and Franchi the self-consistent mode coupling (SCMC) and the effective dephasing approximation (EDA) which are based on the same general approach, but apply to different aspects of the disorder model. The SCMC applies only to models with spatial disorder where only a fraction of possible sites are active in transport. The EDA applies to quantum systems where there is site energy disorder. To find the qualitative behavior of each method, an appropriate lowest order approximation is made to each of these procedures. This is enough to take advantage of the fact that for the behavior around the transition (and in the localized regime) only the small cluster terms are dominate. Both methods predict the correct long time behavior of the transport quantities for diffusive behavior which is not found in any other dynamic theory of disordered systems. The features of the results, all of which are shown here as derivable from a single unified simplistic approach, are found to be in excellent agreement with those found from many different theories with disorder including fractal dynamics, long range interactions of excitons, the Anderson transition and the Haken-Strobl limit.
Programming Satan's Computer Ross Anderson and Roger Needham
Perrig, Adrian
Programming Satan's Computer Ross Anderson and Roger Needham Cambridge University Computer and maliciously wrong at the most inconvenient possible moment. This is a fascinating problem; and we hope attacked. This brings us to the fascinating subject of cryp- tographic protocol failure. 2 Some Simple
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
Key Infection: Smart Trust for Smart Dust Ross Anderson
Perrig, Adrian
Key Infection: Smart Trust for Smart Dust Ross Anderson University of Cambridge Ross become cheaper and more commoditised, they will become attractive to home users and small businesses technology is given by the `Smart Dust' project which is developing tiny sensors [9]. Its goal is to make
Measuring the Cost of Cybercrime Ross Anderson 1
Savage, Stefan
Measuring the Cost of Cybercrime Ross Anderson 1 Chris Barton 2 Rainer B¨ohme 3 Richard Clayton 4 what we believe to be the first systematic study of the costs of cybercrime. It was prepared the problem. For each of the main categories of cybercrime we set out what is and is not known of the direct
POLAR SEA ICE MAPPING FOR SEAWINDS Hyrum S. Anderson
Long, David G.
POLAR SEA ICE MAPPING FOR SEAWINDS by Hyrum S. Anderson A thesis submitted to the faculty, College of Engineering and Technology #12;viii #12;ABSTRACT POLAR SEA ICE MAPPING FOR SEAWINDS Hyrum S sea ice. Advances in microwave remote sensing technology have allowed a large-scale and detailed study
Error Diffusion Using Linear Pixel Shuffling Peter G. Anderson
Anderson, Peter G.
Error Diffusion Using Linear Pixel Shuffling Peter G. Anderson Rochester Institute of Technology Rochester, NY, USA Abstract Linear pixel shuffling error diffusion is a digital halfton ing algorithm that combines the linear pixel shuffling (LPS) order of visiting pixels in an image with diffusion of quanti
Microdissection: a tool for bee chromosome studies Anderson FERNANDES
Microdissection: a tool for bee chromosome studies Anderson FERNANDES 1,2 , Patrícia Elda Sobrinho a microdissection protocol for cytogenetic studies in bees. This methodology was first used in these insects and may chromosomes and others. For this study, the centromeric region of chromosomes in the stingless bee
A Genetic Algorithm for Grammars James Anderson and Joe Staines
Goldschmidt, Christina
A Genetic Algorithm for Grammars James Anderson and Joe Staines July 1, 2010 Background training data. 1 #12;A Genetic Algorithm for Grammars Of course, there are many more grammars than be able to search heuristically. Project Proposal We propose a project which uses a genetic algorithm
Variational ground states for the periodic Anderson model
P. Fazekas
1987-01-01
A trial state of the kind suggested by Brandow is used for the nondegenerate periodic Anderson model with arbitrary band filling. An approximate N-parameter minimisation is carried out analytically. A Gutzwiller-type approximation leads to predicting a magnetic instability even in the valence fluctuation regime.
Partitions of trees and ACA0 Bernard A. Anderson
Hirst, Jeff
Partitions of trees and ACA0 Bernard A. Anderson Jeffry L. Hirst Appalachian State University is equivalent to the subsystem ACA0 of reverse mathemat- ics. In [1], a version of Ramsey's theorem for trees of Ramsey's theorem are also equivalent. Because there are so few examples of proofs involving ACA0
Lifshitz Tails for Continuous Matrix-Valued Anderson Models
NASA Astrophysics Data System (ADS)
Boumaza, Hakim; Najar, Hatem
2015-04-01
This paper is devoted to the study of Lifshitz tails for a continuous matrix-valued Anderson-type model acting on L^2({R}^d)? {C}D , for arbitrary d? 1 and D? 1 . We prove that, under a hypothesis of non-degeneracy of the bottom of the spectrum, the integrated density of states of the model has a Lifshitz behaviour 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. For d=1 , we prove that the bottom of the spectrum is always non-dege nerate, for any matrix-valued periodic background potential, and thus each quasi-one-dimensional Anderson model has a Lifshitz exponent equal to -1/2.
A struggle for freedom; Maxwell Anderson, 1938-1952
Odeski, Thomas Francis
1979-01-01
of the jungle, the evils of collectivism those of the ant-hill. And since we must choose between them I prefer the jungle. After all, we evolved from the jungle. Nothing will ever evolve from the ant-hill. Anderson was convinced that greater individual...
Elizabeth Garrett Anderson and the professionalism of medical publicity
Claire Brock
2008-01-01
A B S T R A C T • This article examines how early women doctors managed their professional and public images in the second half of the nineteenth century through a case study of the career of the first medical woman to qualify in Britain: Elizabeth Garrett Anderson (1836—1917). In fighting for their cause, Victorian women doctors had to
A Study of Diagrammatic Ink in Lecture Richard Anderson a
Anderson, Richard
delivered from a Tablet PC. The main result of the paper is the identification of three specific challenges of reuse, and the ability to share materials across machines and archive arti- facts of the presentation slides with digital ink on a Tablet PC. We collected data using Classroom Presenter (Anderson et al
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
Chu, Shih-I; Zhou, Zhongyuan
2007-01-17
.1087 57.302 57.305 2p?18s 3P 197.9707 57.2464 1P 197.9706 57.2478 57.456 aFrom LYP potential. bCIIOO #3;26#4;. cReference #3;27#4;. dReference #3;28#4;. BRIEF REPORTS PHYSICAL REVIEW A 75, 014501 #1;2007#2; 014501-2 #8;#3; #1;r#2;= #1;1/4#7;#2;#8;nl #3...,3P #1;n=2#5;8#2; are given in Table II along with the theoretical results of Dirac-Fock method #1;DF#2; #3;20#4; and experimental results #3;20#4;. The relative deviations of our excitation energies to the DF and experimental results are less than 0...
Effects of correlated hybridization in the single-impurity Anderson model
NASA Astrophysics Data System (ADS)
Líbero, Valter; Veiga, Rodrigo
2013-03-01
The development of new materials often dependents on the theoretical foundations which study the microscopic matter, i.e., the way atoms interact and create distinct configurations. Among the interesting materials, those with partially filled d or f orbitals immersed in nonmagnetic metals have been described by the Anderson model, which takes into account Coulomb correlation (U) when a local level (energy Ed) is doubled occupied, and an electronic hybridization between local levels and conduction band states. In addition, here we include a correlated hybridization term, which depends on the local-level occupation number involved. This term breaks particle-hole symmetry (even when U + 2Ed = 0), enhances charge fluctuations on local levels and as a consequence strongly modifies the crossover between the Hamiltonian fixed-points, even suppressing one or other. We exemplify these behaviors showing data obtained from the Numerical Renormalization Group (NRG) computation for the impurity temperature-dependent specific heat, entropy and magnetic susceptibility. The interleaving procedure is used to recover the continuum spectrum after the NRG-logarithmic discretization of the conduction band. The development of new materials often dependents on the theoretical foundations which study the microscopic matter, i.e., the way atoms interact and create distinct configurations. Among the interesting materials, those with partially filled d or f orbitals immersed in nonmagnetic metals have been described by the Anderson model, which takes into account Coulomb correlation (U) when a local level (energy Ed) is doubled occupied, and an electronic hybridization between local levels and conduction band states. In addition, here we include a correlated hybridization term, which depends on the local-level occupation number involved. This term breaks particle-hole symmetry (even when U + 2Ed = 0), enhances charge fluctuations on local levels and as a consequence strongly modifies the crossover between the Hamiltonian fixed-points, even suppressing one or other. We exemplify these behaviors showing data obtained from the Numerical Renormalization Group (NRG) computation for the impurity temperature-dependent specific heat, entropy and magnetic susceptibility. The interleaving procedure is used to recover the continuum spectrum after the NRG-logarithmic discretization of the conduction band. Fundação de Amparo à Pesquisa do Estado de São Paulo - FAPESP.
Tatsuro Endo; Daisuke Ikeda; Yukari Kawakami; Yasuko Yanagida; Takeshi Hatsuzawa
2010-01-01
LSPR from nanostructured noble metals such as gold and silver offers great potential for biosensing applications. In this study, a core-shell structured nanoparticle layer substrate was fabricated and the localized surface plasmon resonance (LSPR) optical characteristics were investigated for DNA in aqueous conditions. Factors such as DNA length dependence, concentration dependence, and the monitoring of DNA aspects (ssDNA or dsDNA)
NASA Astrophysics Data System (ADS)
Furusawa, K.; Ishikawa, Y.; Tashiro, M.; Hazu, K.; Nagao, S.; Ikeda, H.; Fujito, K.; Chichibu, S. F.
2013-07-01
Local carrier dynamics around the sub-surface basal-plane stacking faults (BSFs) accidentally formed in a low dislocation density c-plane GaN were studied by the spatio-time-resolved cathodoluminescence measurement. A high photoelectron (PE) emission efficiency of the front-excitation-type PE-gun enabled to investigate sub-surface defect structures with low acceleration voltages. As a result, the presence of an energy transfer channel of excitons from neutral donor bound states to I1-type BSF bound states was confirmed. Careful comparisons of cathodoluminescence intensity mapping images taken at 3.305 eV and those corresponding to I1-BSFs indicated the presence of prismatic-plane stacking faults connecting the BSFs into a bundle.
Pu 4f XPS spectra analyzed in the Anderson impurity model
Cox, L.E.; Peek, J.M. [Los Alamos National Lab., NM (United States). Nuclear Materials Technology Div.; Allen, J.W. [Univ. of Michigan, Ann Arbor, MI (United States). Dept. of Physics
1998-05-09
X-ray photoemission spectra of the {alpha},{beta},{gamma}, and {delta} phases of Pu have been analyzed using the Gunnarsson-Schonhammer implementation of the Anderson impurity model. Changes in the relative intensities of the two spectral features representing mixed f{sup 5} and f{sup 6} final states are in reasonable agreement with the model`s predictions. The coulomb terms, U{sub ff} and U{sub fc}, are quite consistent with those derived from atomic and LDA calculations. Multiplet structure, which agrees with atomic calculations for 4f{sup 13}5f{sup 5}, strongly suggests 5f localization in the final state.
Decoherence-induced conductivity in the one-dimensional Anderson model
Stegmann, Thomas; Wolf, Dietrich E. [Department of Physics, University of Duisburg-Essen and CENIDE, 47048 Duisburg (Germany); Ujsághy, Orsolya [Department of Theoretical Physics, Budapest University of Technology and Economics, Budafoki út 8., H-1521 Budapest (Hungary)
2014-08-20
We study the effect of decoherence on the electron transport in the one-dimensional Anderson model by means of a statistical model [1, 2, 3, 4, 5]. In this model decoherence bonds are randomly distributed within the system, at which the electron phase is randomized completely. Afterwards, the transport quantity of interest (e.g. resistance or conductance) is ensemble averaged over the decoherence configurations. Averaging the resistance of the sample, the calculation can be performed analytically. In the thermodynamic limit, we find a decoherence-driven transition from the quantum-coherent localized regime to the Ohmic regime at a critical decoherence density, which is determined by the second-order generalized Lyapunov exponent (GLE) [4].
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.
Cumulant expansion of the periodic Anderson model in infinite dimensions
NASA Astrophysics Data System (ADS)
Foglio, M. E.; Figueira, M. S.
1997-11-01
The diagrammatic cumulant expansion for the periodic Anderson model with infinite Coulomb repulsion 0305-4470/30/22/024/img5 is considered here for an hypercubic lattice of infinite dimension 0305-4470/30/22/024/img6. The nearest neighbour hopping of the uncorrelated electrons is described exactly by a conduction band, while two different models of hybridization are treated as a perturbation. The same type of simplifications obtained by Metzner for the cumulant expansion of the Hubbard model in the limit of 0305-4470/30/22/024/img7, are also shown to be valid for the periodic Anderson model. The derivation of these properties had to be modified because of the exact treatment of the conduction band.
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.
Anderson and Belnap’s Invitation to Sin
Alasdair Urquhart
2010-01-01
Quine has argued that modal logic began with the sin of confusing use and mention. Anderson and Belnap, on the other hand,\\u000a have offered us a way out through a strategy of nominalization. This paper reviews the history of Lewis’s early work in modal\\u000a logic, and then proves some results about the system in which “A is necessary” is intepreted
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.
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.
Topological Anderson insulator induced by inter-cell hopping disorder
Lv, Shu-Hui [Hebei Advanced Thin Film Laboratory, College of Physics, Hebei Normal University, Hebei 050024 (China); College of Sciences, Hebei University of Science and Technology, Shijiazhuang 050018 (China); Song, Juntao, E-mail: jtsong@mail.hebtu.edu.cn; Li, Yu-Xian, E-mail: yxli@mail.hebtu.edu.cn [Hebei Advanced Thin Film Laboratory, College of Physics, Hebei Normal University, Hebei 050024 (China)
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.
Yukihiro Shimizu; Alex Hewson; Osamu Sakai
1999-01-01
The specific heat and the magnetisation of an impurity Anderson model,which has a non-Kramers doublet lowest state of an f 2 configurationsubject to the tetragonal crystalline electric field,are investigated using the numerical renormalization group method.We examine two cases where the ground states of the system arenon-Fermi-liquid (NFL) of two-channel Kondo type modeland local-Fermi-liquid (LFL), respectively.In the former case the temperature
NASA Astrophysics Data System (ADS)
Theodosiou, Constantine E.
1988-11-01
In a recent paper Allen, Anderson, and Lin
Astronaut Clay Anderson Speaks With S.C. Students - Duration: 25 minutes.
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,...
Particle Beam Excitation Electron Beam Excitation
Schroder, Dieter K.
Microprobe Microanalysis (EMP) Transmission Electron Microscopy (TEM) Scanning Auger Microscopy (SAMParticle Beam Excitation Electron Beam Excitation Scanning Electron Microscopy (SEM) Electron Projector lens Electron multiplier Fluorescent screen X-Y stage Microchannel plate Immersion lens Measures m
Bearing-Only Localization Using Geometrically Constrained Optimization
Mao, Guoqiang
1 Bearing-Only Localization Using Geometrically Constrained Optimization Adrian N. Bishop, Student Member, IEEE, Brian D.O. Anderson, Life Fellow, IEEE, Baris¸ Fidan, Member, IEEE, Pubudu N. Pathirana simulation. Index Terms-- Angle Measurements, Bearings, Geometric Con- straints, Localization, Optimization
Strong localization of photons in certain disordered dielectric superlattices
Sajeev John
1987-01-01
A new mechanism for strong Anderson localization of photons in carefully prepared disordered dielectric superlattices with an everywhere real positive dielectric constant is described. In three dimensions, two photon mobility edges separate high- and low-frequency extended states from an intermediate-frequency pseudogap of localized states arising from remnant geometric Bragg resonances. Experimentally observable consequences are discussed.
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.
Note: Work function change measurement via improved Anderson method.
Sabik, A; Go?ek, F; Antczak, G
2015-05-01
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. PMID:26026572
Note: Work function change measurement via improved Anderson method
NASA Astrophysics Data System (ADS)
Sabik, A.; Go?ek, F.; Antczak, G.
2015-05-01
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.
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,...
A. Andrzejak, D. Kondo, D. P. Anderson NOMS 2010 Exploiting Non-Dedicated Resources
Kondo, Derrick
A. Andrzejak, D. Kondo, D. P. Anderson NOMS 2010 Exploiting Non-Dedicated Resources for Cloud Computing Artur Andrzejak andrzejak@zib.de Zuse Institute Berlin, Germany Derrick Kondo dkondo@imag.fr INRIA Grenoble, France David P. Anderson davea@ssl.berkeley.edu UC Berkeley, USA #12;A. Andrzejak, D. Kondo, D. P
PRINT ONLY: MISSIONS AND INSTRUMENTS Anderson J. A. Robinson M. S.
Rathbun, Julie A.
PRINT ONLY: MISSIONS AND INSTRUMENTS Anderson J. A. Robinson M. S. Challenges Utilizing Pushframe #12;CHALLENGES UTILIZING PUSHFRAME CAMERA IMAGES. J.A. Anderson1 and M.S. Robinson2 , 1 U University (School of Earth and Space Exploration, Box 871404, Tempe, Arizona 85287-1404, robinson
James Anderson's Political Economy--His Influence on Smith and Malthus
Renee Prendergast
1987-01-01
James Anderson's powerful critique of Adam Smith's position on the corn export bounty was published in 1777. It focuse d on Smith's proposition that the bounty could not lead to increased corn production because it could not increase corn's real price. Smit h's response to the critique is traced in later editions of Wealth of Nations. While Anderson's critique of
Singh, Manish
The perceived transmittance of inhomogeneous surfaces and media Barton L. Anderson a,*, Manish the transmittance of inhomogeneous surfaces and media. Previous work (Anderson, B. L. (1999) Stereoscopic surface a transmittance anchoring principle in determining when transparency is perceived. This principle states
ON -DEDEKIND RINGS AND -KRULL RINGS DAVID F. ANDERSON AND AYMAN BADAWI
Badawi, Ayman
ON -DEDEKIND RINGS AND -KRULL RINGS DAVID F. ANDERSON AND AYMAN BADAWI Abstract. The purpose(RNil(R)) = (Nil(R)) = Nil((R)) = Z((R)), T((R)) = RNil(R) 1 #12;2 DAVID F. ANDERSON AND AYMAN BADAWI is quasilocal
The Innovation Butterfly E.G. Anderson Jr. The Innovation Butterfly
Ghosh, Joydeep
.G. Anderson Jr. Maneuver-Driven Competition (PDCA to OODA to SROM) The SROM Cycle The speed of the cycle is completed) #12;The Innovation Butterfly E.G. Anderson Jr. Maneuver-Driven Competition Slow SROM Loop Fast SROM Loop Market Firm Market Firm Faster SROM loops make the firm more agile
Price-Anderson Act - the third decade. Report to Congress
Saltzman, J.
1983-12-01
Subsection 170p. of the Atomic Energy Act of 1954, as amended, requires that the Commission submit to the Congress by August 1, 1983, a detailed report on the need for continuation or modification of Section 170 of the Act, the Price-Anderson provisions. The report is divided into four sections with detailed subject reports appended to the main report. Sections I through III include an examination of issues that the Commission was required by statute to study (i.e., condition of the nuclear industry, state of knowledge of nuclear safety, and availability of private insurance), and discussion of other issues of interest and importance to the Congress and to the public. The subjects covered are as follows: (1) overview of the Price-Anderson system; (2) the state of knowledge of nuclear safety; (3) availability of private insurance; (4) conditions of the nuclear industry; (5) causality and proof of damages; (6) limitation of liability and subsidy; and (7) a proposal that would provide for removal of the limitation of liability but with limited annual liability payments. Section IV of the report contains conclusions and recommendations. Section V contains a bibliography.
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.
Reply. [to the comment by Anderson et al. (1993)
NASA Technical Reports Server (NTRS)
Hegg, Dean A.; Ferek, Ronald G.; Hobbs, Peter V.
1994-01-01
While Hegg et al. (1993) accepts the criticism of Anderson et al. (1994) in principle, this involves the adoption of an aerosol composition model and the model that they propose to reconcile these observations with the assertion of Charlson et al. (1992) does not agree with many observations, particularly those made over the North Atlantic Ocean. Although the use of a gain factor (i.e. the partial derivative of aerosol mass with respect to the sulfate ion), proposed by Anderson et al., may be valid for particular cases where a proposed composition model really reflects the actual aerosol composition, this procedure is considered questionable in general. The use of sulfate as a tracer for nonsulfate aerosol mass is questionable, because in the present authors' data set, sulfate averaged only about 26% of the dry aerosol mass. The ammonium mass associated with sulfate mass is not analogous to that betwen the oxygen mass and sulfur mass in the sulfate ion. Strong chemical bonds are present between sulfur and oxygen in sulfate, whereas ammonium and sulfate in haze droplets are ions in solution that may or may not be associated with one another. Thus, there is no reason to assume that sulfate will act as a reliable tracer of ammonium mass. Hegg et al. expresses the view that their approach used for estimating sulfate light scattering efficiency is appropriate for the current level of understanding of atmospheric aerosols.
Quantum Monte Carlo investigation of Knight shift anomaly in Periodic Anderson model
NASA Astrophysics Data System (ADS)
Jiang, Mi; Curro, Nicholas; Scalettar, Richard; UC Davis Team; UC Davis Team
2014-03-01
We report a Determinant Quantum Monte Carlo investigation of the Knight shift anomaly observed in nuclear magnetic resonance (NMR) of heavy fermion materials. As opposed to normal Fermi liquids, the Knight shift in heavy fermion materials deviates from the total susceptibility ? below a crossover temperature T*. This deviation is believed to originate in the different temperature dependence of the conduction electron and local moment components of the total susceptibility ?. Here we quantify the behavior of ?cc(T) ,?cf(T) , and ?ff(T) in the framework of periodic Anderson model (PAM), focussing on the evolution with different degree of conduction electron-local moment hybridization. These results confirm several predictions of the two-fluid theory of the Knight shift anomaly, including the demonstration of a universal logarithmic divergence of the contribution of the heavy electrons to the Knight shift. This universal behavior, which occurs with decreasing temperature below T* in the paramagnetic state, agrees well with experimental findings, and indicates that different heavy fermion materials exhibit a common scaling, differing only in the coherence temperature scale, T*.
Filatov, Michael; Huix-Rotllant, Miquel; Burghardt, Irene
2015-05-14
State-averaged (SA) variants of the spin-restricted ensemble-referenced Kohn-Sham (REKS) method, SA-REKS and state-interaction (SI)-SA-REKS, implement ensemble density functional theory for variationally obtaining excitation energies of molecular systems. In this work, the currently existing version of the SA-REKS method, which included only one excited state into the ensemble averaging, is extended by adding more excited states to the averaged energy functional. A general strategy for extension of the REKS-type methods to larger ensembles of ground and excited states is outlined and implemented in extended versions of the SA-REKS and SI-SA-REKS methods. The newly developed methods are tested in the calculation of several excited states of ground-state multi-reference systems, such as dissociating hydrogen molecule, and excited states of donor-acceptor molecular systems. For hydrogen molecule, the new method correctly reproduces the distance dependence of the lowest excited state energies and describes an avoided crossing between the doubly excited and singly excited states. For bithiophene-perylenediimide stacked complex, the SI-SA-REKS method correctly describes crossing between the locally excited state and the charge transfer excited state and yields vertical excitation energies in good agreement with the ab initio wavefunction methods. PMID:25978880
NASA Astrophysics Data System (ADS)
Filatov, Michael; Huix-Rotllant, Miquel; Burghardt, Irene
2015-05-01
State-averaged (SA) variants of the spin-restricted ensemble-referenced Kohn-Sham (REKS) method, SA-REKS and state-interaction (SI)-SA-REKS, implement ensemble density functional theory for variationally obtaining excitation energies of molecular systems. In this work, the currently existing version of the SA-REKS method, which included only one excited state into the ensemble averaging, is extended by adding more excited states to the averaged energy functional. A general strategy for extension of the REKS-type methods to larger ensembles of ground and excited states is outlined and implemented in extended versions of the SA-REKS and SI-SA-REKS methods. The newly developed methods are tested in the calculation of several excited states of ground-state multi-reference systems, such as dissociating hydrogen molecule, and excited states of donor-acceptor molecular systems. For hydrogen molecule, the new method correctly reproduces the distance dependence of the lowest excited state energies and describes an avoided crossing between the doubly excited and singly excited states. For bithiophene-perylenediimide stacked complex, the SI-SA-REKS method correctly describes crossing between the locally excited state and the charge transfer excited state and yields vertical excitation energies in good agreement with the ab initio wavefunction methods.
Materials Modification by Electronic Excitation
NASA Astrophysics Data System (ADS)
Itoh, Noriaki; Stoneham, Marshall
2000-12-01
Photography is a well-known example of changing a material by exciting it with light. This book examines a special case of a more general approach, which uses new lasers or electron beams to address some of the current needs emerging in microelectronics, photonics, and nanotechnology. It analyzes the important features of the changes induced by electronic excitation, identifies what is critical, and provides a basis from which materials modification can be developed successfully. It addresses ideas such as energy localization and charge localization, with detailed comparisons of experiment and theory. It also identifies the ways this understanding links to technological needs, such as selective removal of material, controlled changes, altering the balance between process steps, and possibilities of quantum control. This book will be of particular interest to research workers in physics, chemistry, electronic engineering and materials science.
Extended states in 1-D Anderson chain diluted by periodic disorder
NASA Astrophysics Data System (ADS)
Lazo, E.; Onell, M. E.
2001-05-01
In this work, we generalize the periodic random Anderson model, because instead of using constant site energies between disordered sites, we dilute the Anderson lattice by means of ( P-1) site energies given by an arbitrary periodic function ? l=f (l)=f (l+P), l=2, 3,…,P , where P is the period of the Anderson lattice. Using a block decimation scheme, we analytically find the mathematical conditions for the appearing of delocalized states with critical energies Ec. In addition, we find some of the symmetries associated to the function f (l) which allows the propagation of extended electronic waves through our generalized model.
Functional-integral study of the asymmetric Anderson model for dilute fluctuating-valence systems
NASA Astrophysics Data System (ADS)
Xianxi, Dai; Ting, Chin-Sen
1983-11-01
The functional-integral method in the harmonic approximation which was developed by Amit and Keiter has been extended to study the asymmetric Anderson model. This model gives a valid description of dilute rare-earth ions in metal. The magnetic susceptibility and the occupation number of the localized or f electrons are expressed in terms of some series of double integrals. These double integrals are evaluated numerically by an integration method in number theory. Our results for the temperature-dependent magnetic susceptibility agree quite well with those of renormalization-group calculation by Krishna-Murthy et al. for the f level lying above the Fermi level. However, when the f level lies below the Fermi level, the result of the present approximation loses its agreement with that of the renormalization-group calculation at low temperatures. The f-electron occupation number has also been calculated as a function of temperature and as a function of the energy level of f electrons.
An Archaeological Survey of a Proposed Borrow Pit in Anderson County, Texas
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...
Taking on Titan: Meet Carrie Anderson - Duration: 2 minutes, 45 seconds.
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...
Anderson, James
Baruah Department of Computer Science The University of North Carolina at Chapel Hill {fishern, anderson, baruah}@cs.unc.edu Abstract Most prior theoretical research on partitioning algo- rithms for real
A guide to source materials of the life and work of Lawrence B. Anderson '30
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 ...
All-solid-state ultrafast lasers facilitate multiphoton excitation fluorescence imaging
David L. Wokosin; Victoria Centonze; John G. White; David Armstrong; Gordon Robertson; Allister I. Ferguson
1996-01-01
Improvements in ultrafast laser technology have enabled a new excitation mode for optical sectioning fluorescence microscopy: multiphoton excitation fluorescence imaging. The primary advantages of this technique over laser scanning confocal imaging derive from the localized excitation volume; additional advantages accrue from the longer wavelength of the excitation source. Recent advances in all-solid-state, ultrafast (subpicosecond) laser technology should allow the technique
NASA Astrophysics Data System (ADS)
Narasimha Raju, Ch.; Chatterjee, Ashok
2015-05-01
The single-impurity Anderson-Holstein model is investigated in the presence of a magnetic field by an improved variational method. The phonon degrees of freedom are first eliminated by a modified Lang-Firsov transformation followed by a zero-phonon averaging. The resulting Hamiltonian is then treated by a cluster variational method to study the effects of the electron-phonon interaction and the magnetic field on the ground state energy, local magnetic moment and the binding energy between the magnetic impurity and the conduction electrons.
DETERMINATION OF LOCAL MAGNITUDE, ML, FROM STRONG MOTION ACCELEROGRAMS
HIROO KANAMORI; PAUL C. JENNINGS
1978-01-01
A technique is presented for determination of local magnitude, ML, from strong-motion accelerograms. The accelerograph records are used as an accel- eration input to the equation of motion of the Wood-Anderson torsion seismo- graph to produce a synthetic seismogram which is then read in the standard manner. When applied to 14 records from the San Fernando earthquake, the resulting ML
Effect of correlation in a local description for valence fluctuations
Y. Hammoud; M. A. Khan; C. Demangeat
1982-01-01
The atomic limit of the Anderson lattice Hamiltonian is solved in the case where the Coulomb repulsive U between 4f electrons is greater than the fd hybridization energy. This local model is extended to take into account hybridization between the central atom and its neighbouring sites. The ground state of the two electrons case found by diagonalization of the singlet
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.
Spatiotemporal control of nanooptical excitations
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
Receiver-exciter controller design
NASA Astrophysics Data System (ADS)
Jansma, P. A.
1982-06-01
A description of the general design of both the block 3 and block 4 receiver-exciter controllers for the Deep Space Network (DSN) Mark IV-A System is presented along with the design approach. The controllers are designed to enable the receiver-exciter subsystem (RCV) to be configured, calibrated, initialized and operated from a central location via high level instructions. The RECs are designed to be operated under the control of the DMC subsystem. The instructions are in the form of standard subsystem blocks (SSBs) received via the local area network (LAN). The centralized control provided by RECs and other DSCC controllers in Mark IV-A is intended to reduce DSN operations costs from the Mark III era.
Receiver-exciter controller design
NASA Technical Reports Server (NTRS)
Jansma, P. A.
1982-01-01
A description of the general design of both the block 3 and block 4 receiver-exciter controllers for the Deep Space Network (DSN) Mark IV-A System is presented along with the design approach. The controllers are designed to enable the receiver-exciter subsystem (RCV) to be configured, calibrated, initialized and operated from a central location via high level instructions. The RECs are designed to be operated under the control of the DMC subsystem. The instructions are in the form of standard subsystem blocks (SSBs) received via the local area network (LAN). The centralized control provided by RECs and other DSCC controllers in Mark IV-A is intended to reduce DSN operations costs from the Mark III era.
Quantum fluctuations and excitations in antiferromagnetic quasicrystals
Wessel, Stefan [Institut fuer Theoretische Physik III, Universitaet Stuttgart, D-70550 Stuttgart (Germany); Milat, Igor [Theoretische Physik, ETH Zuerich, CH-8093 Zurich (Switzerland)
2005-03-01
We study the effects of quantum fluctuations and the excitation spectrum for the antiferromagnetic Heisenberg model on a two-dimensional quasicrystal, by numerically solving linear spin-wave theory on finite approximants of the octagonal tiling. Previous quantum Monte Carlo results for the distribution of local staggered magnetic moments and the static spin structure factor are reproduced well within this approximate scheme. Furthermore, the magnetic excitation spectrum consists of magnonlike low-energy modes, as well as dispersionless high-energy states of multifractal nature. The dynamical spin structure factor, accessible to inelastic neutron scattering, exhibits linear-soft modes at low energies, self-similar structures with bifurcations emerging at intermediate energies, and flat bands in high-energy regions. We find that the distribution of local staggered moments stemming from the inhomogeneity of the quasiperiodic structure leads to a characteristic energy spread in the local dynamical spin susceptibility, implying distinct nuclear magnetic resonance spectra, specific for different local environments.
Ultrafast optical excitation of magnetic skyrmions
NASA Astrophysics Data System (ADS)
Ogawa, N.; Seki, S.; Tokura, Y.
2015-04-01
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.
Ultrafast optical excitation of magnetic skyrmions.
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
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.
Dynamic light diffusion, three-dimensional Anderson localization and lasing in inverted opals
C. Conti; A. Fratalocchi
2008-01-01
Photons propagate in photonic crystals in the same way as electrons propagate in solids. The periodical refractive index induces forbidden frequency bands, which nurture a variety of novel integrated devices and several fundamental studies ranging from threshold-less lasers to quantum computing. However, these investigations have to face the unavoidable disorder of real-world structures: if on one hand it largely hampers
Energy-Level and Wave-Function Statistics in the Anderson Model of Localization
Bernhard Mehlig; Michael Schreiber
Universal aspects of correlations in the spectra and wave functions of closed, complex quantum systems can be described by\\u000a random-matrix theory (RMT) [1]. On small energy scales, for example, the eigenvalues, eigenfunctions and matrix elements of\\u000a disordered quantum systems in the metallic regime [2] or those of classically chaotic quantum systems [3] exhibit universal\\u000a statistical properties very well described by
Anderson localization in a spatially correlated random potential under a strong magnetic field
Boyer, Edmond
. It is known that some materials such as GaAs-AlGaAs heterojunctions are indeed described by such correlated]. In the usual approach of a white noise random potential the impurities at different points are sta- tistically magnetic field, in which the magnetic length 1 eB is small, the model of a white noise random potential
Isaac Newton Institute for Mathematical Sciences Mathematics and Physics of Anderson Localization
applies to the transport of many types of waves: quantum, electromagnetic, acoustic, and even ocean waves propagating over a random seabed. It also proved to be crucial for an understanding of such important
Exciting Effects of Excited 0+ Energies
McCutchan, E.A.; Zamfir, N.V.; Casten, R.F. [Wright Nuclear Structure Laboratory, Yale University, New Haven, CT 06520 (United States)
2004-09-13
The significance of considering excited 0+ states is discussed in both an experimental and theoretical context. Experimental results on possible phase transitional nuclei are presented. New calculations on Yb and Hf nuclei in the framework of the IBA-1 model are presented and compared to previous fits in this region.
Snyder, Jeff; Haas, Martin; Hennig, Jürgen; Zaitsev, Maxim
2012-02-01
Parallel excitation is being studied intensively for applications in MR imaging and in particular for selecting arbitrary shapes as regions of interest. In this work, parallel excitation was applied to arbitrarily shaped voxel selection in spectroscopy and investigated for different excitation k-space trajectories (radial, rectilinear, and spiral) and acceleration factors. Each trajectory was segmented into multiple excitations to increase the overall bandwidth during target selection. Acceleration by parallel excitation was used to decrease the number of segments. Evaluation of spatial and spectral localization of the target of interest was performed in simulation and phantom experiments, and was compared with the point resolved spectroscopy (PRESS) experiment with standard voxels. The selective excitation experiments demonstrated excellent spatial localization and a broad frequency response, although PRESS was superior in direct comparisons with respect to signal-to-noise ratio (SNR) and outer volume suppression. Extensive SNR variation was observed dependent on trajectory (8%-90%), with the preferred radial case producing approximately 40%-60% SNR of the PRESS case. Accelerated trajectories at R = 4 provided comparable artifact signal and target excitation accuracy compared with their nonaccelerated counterparts; however, further acceleration (R = 8) resulted in increased artifact (33% increase at R = 8). PMID:21721040
Second order U-perturbation approach to the Anderson lattice model in high dimensions
NASA Astrophysics Data System (ADS)
Schweitzer, H.; Czycholl, G.
1989-01-01
We study the periodic Anderson model (PAM), i.e. highly correlated, localized f-shells on a d-dimensional (simple-cubic) lattice hybridized with the states of a (tight-binding) conduction band. At least for the symmetric PAM (i.e. the unperturbed f-level energy E f and E f+U lie symmetric around the chemical potential, where U denotes the on-site Coulomb correlation between the f-electrons,) the second order (standard) U-perturbation treatment around the non-magnetic Hartree-Fock solution provides for a proper approximate treatment of the PAM even for relatively large values of U. In this communication we study this approach in the limit of high dimensions d of the underlying lattice. In this limit, which has recently been introduced by Metzner and Vollhardt for the Hubbard model, the selfenergy becomes site-diagonal, i.e. momentum independent, because of which the explicit calculation of the selfenergy in second order in U is much simpler than in lower dimensions. But one still obtains an f-electron spectral function, which shows all the properties, which are usually expected for heavy fermion systems, in particular single-particle peaks near to E f and E f+U, a strongly temperature dependent many-particle (Kondo) resonance peak near to the chemical potential, a hybridization (coherence) gap at the chemical potential, etc. Thus practical calculations may become much simpler for high d, but the essential physics remains the same as for realistic low d (=1,2,3).
How the Edwards-Anderson Model reaches its Mean-Field Limit; Simulations in d=3,...,7
NASA Astrophysics Data System (ADS)
Boettcher, Stefan; Falkner, Stefan
2012-02-01
Extensive computations of ground state energies of the Edwards-Anderson spin glass on bond-diluted, hypercubic lattices are conducted in dimensions d=3,,. Results are presented for bond-densities exactly at the percolation threshold, p=pc, and deep within the glassy regime, p>pc, where finding ground-states becomes a hard combinatorial problem. The ``stiffness'' exponent y that controls the formation of domain wall excitations at low temperatures is determined in all dimensions. Finite-size corrections of the form 1/N^? are shown to be consistent throughout with the prediction ?=1-y/d. At p=pc, an extrapolation for d->? appears to match our mean-field results for these corrections. In the glassy phase, ? does not approach the value of 2/3 for large d predicted from simulations of the Sherrington-Kirkpatrick spin glass. However, the value of ? reached at the upper critical dimension does match certain mean-field spin glass models on sparse random networks of regular degree called Bethe lattices.[4pt] [1] S. Boettcher and S. Falkner, arXiv:1110.6242;[2] S. Boettcher and E. Marchetti, PRB77, 100405 (2008);[3] S. Boettcher, PRL95, 197205 (2005).
Optimizing Disinfection Pretreatment using Excitation-emission Matrix Fluorescence Spectroscopy
Katherine Y. Bell; Juan Sánez; Martha J. M. Wells
2012-01-01
Excitation-emission matrix fluorescence spectroscopy (EEM) can be used to characterize organic matter present in water samples. When excited, the intensity of fluorescence emitted can be used to generate a representation of organic matter makes it possible to localize fluorescence centers related to particular groups, which can ‘fingerprint’ a sample. The technique is applicable to wastewater samples to identify contributors of
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.
Excitation Mechanisms of RE Ions in Semiconductors
NASA Astrophysics Data System (ADS)
Braud, Alain
This chapter presents an overview of the mechanisms responsible for the excitation of optically active rare-earth (RE) ions in semiconductors. Besides resonant excitation of the RE 4f shell, several non-resonant processes can take place in which the host is excited first. These indirect mechanisms involve nonradiative transfer of the recombination energy of electrons and holes to nearby RE ions. Distinct excitation processes arise because of the various conditions under which the electron may recombine with a hole. The different possibilities are presented and discussed in the first part of this chapter. Carriers of opposite charge bind to each other to form either a free exciton or a trapped (bound) exciton. In the latter case, the trapping can arise from the incorporation of RE ions which induces distortions of the host lattice. The exciton trapping can also be due to an impurity, a local defect or even an extended defect. Other possible mechanisms involve the capture of an electron by the 5d shell changing the valence state from trivalent to divalent with the subsequent capture of a hole. Finally, the role of impurities associated with donor-acceptor pairs in the recombination of electrons and holes with energy transfer to RE ions is discussed. In the second part of this chapter the specific case of RE-doped GaN is considered. Results are presented to show that local defects play a major role in the excitation process by binding excitons with a subsequent energy transfer to RE ions. A general modelling of the RE excitation mechanism mediated by bound excitons (BE) is presented and discussed. Finally, experiments using two excitation sources are shown to give valuable information concerning the RE-related defects.
Lemarie, Gabriel; Delande, Dominique [Laboratoire Kastler Brossel, UPMC-Paris 6, ENS, CNRS, 4 Place Jussieu, F-75005 Paris (France); Chabe, Julien; Szriftgiser, Pascal; Garreau, Jean Claude [Laboratoire PhLAM, , Universite de Lille 1, CNRS, CERLA, F-59655 Villeneuve d'Ascq Cedex (France); Gremaud, Benoit [Laboratoire Kastler Brossel, UPMC-Paris 6, ENS, CNRS, 4 Place Jussieu, F-75005 Paris (France); Centre for Quantum Technologies, National University of Singapore, 3 Science Drive 2, Singapore 117543 (Singapore)
2009-10-15
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 wave function 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 {nu}=1.59{+-}0.01, which is found to be equal to the one previously computed for the Anderson model.
Experimental Observation of the Anderson Metal-Insulator Transition with Atomic Matter Waves
Chabe, Julien; Szriftgiser, Pascal; Garreau, Jean Claude [Laboratoire de Physique des Lasers, Atomes et Molecules, Universite des Sciences et Technologies de Lille, CNRS, CERLA, F-59655 Villeneuve d'Ascq Cedex (France); Lemarie, Gabriel; Gremaud, Benoit; Delande, Dominique [Laboratoire Kastler-Brossel, Universite Pierre et Marie Curie-Paris 6, ENS, CNRS, 4 Place Jussieu, F-75005 Paris (France)
2008-12-19
We realize experimentally an atom-optics quantum-chaotic system, the quasiperiodic kicked rotor, which is equivalent to a 3D disordered system that allows us to demonstrate the Anderson metal-insulator transition. Sensitive measurements of the atomic wave function and the use of finite-size scaling techniques make it possible to extract both the critical parameters and the critical exponent of the transition, the latter being in good agreement with the value obtained in numerical simulations of the 3D Anderson model.
Effect of polymer microenvironment on excitation energy migration and transfer.
Misra, Vinita; Mishra, Hirdyesh
2008-04-10
Excitation energy transfer between the dye pair acriflavine (donor) to rhodamine-6G (acceptor) in various polymers [polyvinyl alcohol (PVA), cellulose acetate, and polymethyl methacrylate (PMMA)] was studied using steady-state and time-resolved fluorescence spectroscopy at room temperature. In all these polymers, at higher acceptor concentrations, direct energy transfer from acriflavine to rhodamine-6G followed the Förster theory, which is indicated by the agreement in the values of the observed critical transfer distance with that calculated from spectral overlap. On the other hand, at low acceptor concentrations, the excitation energy migration influences the kinetics, resulting in a significantly higher value of the observed critical transfer distance, which is explained on the basis of Loring et al. (Loring, R. F.; Anderson, H. C.; Fayer, M. D. J. Chem. Phys. 1984, 80, 5731-5744) and Huber (Huber, D. L. Phys. Rev. B: Condens. Matter Mater. Phys. 1979, 20 2307-2314) theories. It was observed that the spectral overlap for donor-donor transport (excitation migration) and donor-acceptor transfer (energy transfer) and thereby other energy transfer parameters were influenced by the microenvironment of the polymers. The efficiency of energy transfer (eta) was the highest in PMMA and the lowest in PVA. Further, the study of acceptor dynamics under energy transfer showed that the rise time of the acceptor also depends on the nature of the polymer microenvironment. PMID:18348559
Influence of local spin polarization to the Kondo effect
NASA Astrophysics Data System (ADS)
Li, Huan; Guo, Wei
2007-03-01
We use the spin non-degenerate single impurity Anderson model to investigate the influence of the local spin polarization to the Kondo effect. By using the Schrieffer-Wolff transformation, we obtain a generalized s-d exchange Hamiltonian, which describes the interaction between a polarized local spin and conduction electrons. In this case, the singlet is no longer an eigenstate as shown by variational calculations where the splitting of the local energy ? = ? d? - ? d? can be arbitrarily small. The local spin polarization generates the instability of the singlet ground state of the S = 1/2 s-d exchange model.
Shouting to be Heard in Advertising Simon P. Anderson and Andr de Palma
Paris-Sud XI, Université de
Shouting to be Heard in Advertising Simon P. Anderson and André de Palma July 2011 revised October 2012 Abstract Advertising competes for scarce consumer attention, so more profitable advertisers send of loud shouters or large range of quiet whisperers. All advertisers prefer there to be less shouting
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…
Michigan, University of
1 Web Search with Metadata Links and Multimedia Presentations G. Ozsoyoglu, M. R. Anderson, Z. M. Ozsoyoglu Department of Electrical Engineering and Computer Science Case Western Reserve University, and report its preliminary testing. Contact Author: Gultekin Ozsoyoglu tekin@eecs.cwru.edu http
von Delft, Jan
Kondo screening cloud in the single-impurity Anderson model: A density matrix renormalization group through the mechanism of the Kondo effect. This gives rise to spin-spin correlations between the magnetic this phenomenon, the so-called Kondo cloud, by means of the density matrix renormalization group method
Serial exploitation of global sea cucumber fisheries Sean C Anderson1
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
SILK { a playful blend of Scheme and Java Kenneth R. Anderson, BBN Technologies, Cambridge, MA
Strickland, Stevie
SILK { a playful blend of Scheme and Java Kenneth R. Anderson, BBN Technologies, Cambridge, MA) interpreter in Java [after [6] p. 176]. Abstract SILK (Scheme in about 50 K) is a compact Scheme imple- mented Scheme in Java, but its access to Java was awkward. The current version has altered SILK's syntax
Virtual herding for flexible livestock management a review Dean M. AndersonA,D
. Additional keywords: grazing systems, hoof-action, livestock management, paddocks, pastures, plantanimalVirtual herding for flexible livestock management a review Dean M. AndersonA,D , Rick E. Estell Cruces, NM 88003, USA. B Department of Animal and Range Sciences, New Mexico State University, Las Cruces
The visual core of a hyperbolic 3manifold James W. Anderson and Richard D. Canary \\Lambda
Canary, Dick
The visual core Before describing the basic properties of the visual core, we give some definitionsThe visual core of a hyperbolic 3manifold James W. Anderson and Richard D. Canary \\Lambda Faculty of the visual core of a hyperbolic 3manifold N = H 3 =\\Gamma. One may think of the visual core as a harmonic
Bio390 Glucose and the Kidney ANSWERS thanks to Dr. J.F. Anderson,
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
D. L. Shepelyansky
2011-02-22
The critical exponents for the Anderson transition in three and four effective dimensions are discussed on the basis of previous data obtained for the frequency modulated kicked rotator. Without appeal to a scaling function they are shown to be in a satisfactory agreement with the theoretical relation known for them.
Polar Sea Ice Mapping Using SeaWinds Data Hyrum S. Anderson and David G. Long
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 of Bayes detection to produce sea ice extent maps. Statistical models for sea ice and ocean are represented
Journal of Philosophy, Inc. Author(s): Alan Ross Anderson and Nuel D. Belnap, Jr.
Belnap, Nuel
Journal of Philosophy, Inc. Enthymemes Author(s): Alan Ross Anderson and Nuel D. Belnap, Jr. Source: The Journal of Philosophy, Vol. 58, No. 23, American Philosophical Association Eastern Division Fifty: Journal of Philosophy, Inc. Stable URL: http://www.jstor.org/stable/2023169 Accessed: 28/05/2009 15
ANALYSIS OF SOME PHYSICAL PROPERTIES OF CERIUM COMPOUNDS IN THE ANDERSON MODEL
Paris-Sud XI, Université de
E 1105 ANALYSIS OF SOME PHYSICAL PROPERTIES OF CERIUM COMPOUNDS IN THE ANDERSON MODEL P the theory of Lacroix-Lyon-Caen et al., who have calculated the magnetic susceptibility of a cerium Kondo of the exchange parameter 0393n(EF) and the Kondo temperature TK of some cerium compounds from susceptibility
What Drives the Choice of a Third Party Logistics Provider? Edward Anderson , Tim Coltman*
Coltman, Tim
1 What Drives the Choice of a Third Party Logistics Provider? Edward Anderson , Tim Coltman and the direction of the research project. #12;2 What Drives the Choice of a Third Party Logistics Provider of their distinctive value propositions a fact one would also expect holds true when companies choose a logistics
Dystopian Visions of Global Capitalism: Philip Reeve's "Mortal Engines" and M.T Anderson's "Feed"
ERIC Educational Resources Information Center
Bullen, Elizabeth; Parsons, Elizabeth
2007-01-01
This article examines Philip Reeve's novel for children, "Mortal Engines", and M.T. Anderson's young adult novel, "Feed", by assessing these dystopias as prototypical texts of what Ulrich Beck calls risk society. Through their visions of a fictional future, the two narratives explore the hazards created by contemporary techno-economic progress,…
Real-Time Character Animation for Computer Games Eike F Anderson
Davies, Christopher
Real-Time Character Animation for Computer Games Eike F Anderson National Centre for Computer Animation Bournemouth University ABSTRACT The importance of real-time character animation in computer games and prospects of their real-time application, ranging from the animation of simple articulated objects to real-time
Generation of the S boxes of Tiger Ross Anderson 1 and Eli Biham 2
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
Albert E. Myles; Rachael Carter
2011-01-01
Evaluating the Economic Impact of Festivals and Special Events: Lessons From the 32st Annual Peter Anderson Arts and Crafts Festival in Ocean Springs, Mississippi Background: Festivals are an integral part of the economies of most communities in Mississippi. The economic benefits of festivals can be assigned a dollar value, but no amount of money will accurately reflect the personal and
How democratic will e-Democracy be? Stuart Anderson Massimo Felici
Felici, Massimo
How democratic will e-Democracy be? Stuart Anderson Massimo Felici LFCS, School of Informatics developments (e.g., e-Government, e-Democracy, e-Voting, etc.) of the Information Society expose the limits multidisciplinary audi- ence. This panel advocates a multidisciplinary debate on e-Democracy: How democratic will e-Democracy
Phase diagram for Anderson disorder: Beyond single-parameter scaling Nigel Goldenfeld
Haydock, Roger
Phase diagram for Anderson disorder: Beyond single-parameter scaling Nigel Goldenfeld Department, Cambridge CB3 0WA, United Kingdom Roger Haydock Department of Physics and Materials Science Institute, 1274 in a disordered potential is transformed analytically and exactly to a basis of random extended states leading
Rebound Discharge in Deep Cerebellar Nuclear Neurons Reza Tadayonnejad & Dustin Anderson &
Turner, Ray
Rebound Discharge in Deep Cerebellar Nuclear Neurons In Vitro Reza Tadayonnejad & Dustin Anderson the capacity to translate membrane hyperpolarizations into a rebound increase in firing frequency. The primary. In particular, it was shown that large diameter cells in the rat DCN exhibit two phenotypes of rebound discharge
A Limit Study of JavaScript Parallelism Emily Fortuna Owen Anderson Luis Ceze Susan Eggers
Anderson, Richard
A Limit Study of JavaScript Parallelism Emily Fortuna Owen Anderson Luis Ceze Susan Eggers Computer://sampa.cs.washington.edu Abstract--JavaScript is ubiquitous on the web. At the same time, the language's dynamic behavior makes on the potential parallelism of JavaScript appli- cations, including popular web pages and standard Java
Decadal climate cycles and declining Columbia River salmon James J. Anderson
Washington at Seattle, University of
1 Decadal climate cycles and declining Columbia River salmon James J. Anderson School of Fisheries - This paper explores the effects of the interaction of anthropogenic trends and climate cycles on salmon river salmon production resulted from the interactions of human activities and climatic regime shifts
Stuart, Steven J.
233 Faculty Anderson, David P., Adjunct Professor, Chemical and Biomolecular Engineering. BA, Associate Professor, Parks, Recreation, and Tourism Management. BA, Illinois Wesleyan University, 1992; MS Professor, History. BA, University of North Carolina, 1990; MA, 1994, PhD, 1998, University of Mississippi
Salvucci, Dario D.
domain knowledge, and to decide whether to output the response during or after computation. The ACT-R theory (Anderson, 1993) seems well-suited to address these challenges. ACT-R allows for the creation strategies. We are currently experimenting with an ACT-R model of the task to ascertain its ability
An Integrated Theory of the Mind John R. Anderson and Daniel Bothell
Byrne, Mike
University Adaptive control of thoughtrational (ACTR; J. R. Anderson & C. Lebiere, 1998) has evolved are presented as examples of specialized systems in ACTR. These modules are associated with distinct cortical. We have been working on a cognitive architecture called adaptive control of thoughtrational (ACTR
Demonstration of the Secure Wireless Agent Testbed (SWAT) Gustave Anderson Andrew Burnheimer will demonstrate the Secure Wireless Agent Testbed (SWAT), a unique facility developed at Drexel University systems. SWAT is an implemented system that fully integrates: (1) mobile agents, (2) wireless ad hoc multi
Understanding Diagrammatic Ink in Lecture Richard Anderson, Crystal Hoyer, Craig Prince,
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
On the Stability of Web Crawling and Web Reid Anderson1
Chaudhuri, Surajit
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
High-Performance Task Distribution for Volunteer Computing David P. Anderson
Korpela, Eric J.
High-Performance Task Distribution for Volunteer Computing David P. Anderson Eric Korpela Rom], Distributed.net [6] and Folding@home [12]. Volunteer computing is being used in high-energy physics, molecular overloaded, requests fail and hosts become idle. Thus, server performance can limit the computing capacity
LEGO MindStorms: Not Just for K-12 Anymore Frank Klassner, Scott D. Anderson
Klassner, Frank
LEGO MindStorms: Not Just for K-12 Anymore Frank Klassner, Scott D. Anderson Department 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 Robotics
AUTO ANSWER CIRCUIT DESIGN FOR AN ANDERSON JACOBSON AD 342 MODEM
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...
Biology 390 Problem: Evaporative Water Loss and Temp Reg. thanks to Dr. J.F. Anderson,
Prestwich, Ken
by evaporative cooling during one day by a 70 kg mammal whose rate of metabolism is 3,000 Kcal/day. Assume evaporative cooling is the only mode of heat exchange this mammal can use to regulate its body temperature, iBiology 390 Problem: Evaporative Water Loss and Temp Reg. thanks to Dr. J.F. Anderson, Dept Zoology
Acetaldehyde Aldol Condensation Kinetics J. 8. ANDERSON' and M. S. PETERS
Anderson, James B.
Acetaldehyde Aldol Condensation Kinetics J. 8. ANDERSON' and M. S. PETERS University of Illinois, Urbana, 111. ACETALDEHYDEmay react to form aldol when- ever acetaldehyde and hydroxide ions are present reactions such as the formation of pentaerythrose. The mechanism of the acetaldehyde aldol reaction has been
ON STATIONARY VACUUM SOLUTIONS TO THE EINSTEIN EQUATIONS MICHAEL T. ANDERSON
Anderson, Michael
systems, e.g. stars * *or black holes. The reasoning here is that as one moves further and further away physical syste* *ms such as isolated stars or black holes, outside regions of matter. The most important MICHAEL T. ANDERSON 0.Introduction. A stationary space-time (M, g
Inference of Tamoxifen's Effects on Prevention of Breast U T M. D. Anderson Cancer Center
Jin, Jiashun
Inference of Tamoxifen's Effects on Prevention of Breast Cancer by Yu Shen U T M. D. Anderson Cancer Center Department of Biostatistics, Unit 1411 1515 Holcombe Blvd, Houston, TX 77030 EMAIL yshen Surgical Adjuvant Breast and Bowel Project's Breast Cancer Prevention Trial (NSABP- BCPT), evaluated
A Novel Low-Power FPGA Routing Switch Jason H. Anderson and Farid N. Najm
Najm, Farid N.
A Novel Low-Power FPGA Routing Switch Jason H. Anderson and Farid N. Najm Department of Electrical FPGA routing switch that can operate in three different modes: high-speed, low-power or sleep. High in industrial FPGA designs. Specifi- cally, we show that a considerable fraction of routing switches may
Plate Tectonics as a Far-From-Equilibrium Self-Organized System Don L. Anderson
Anderson, Don L.
Plate Tectonics as a Far- From- Equilibrium Self-Organized System By Don L. Anderson Word Count: 3 and other forces at the top. Plate tectonics was once regarded as passive motion of plates on top of mantle convection cells but it now appears that continents and plate tectonics organize the flow in the mantle
Nanoscale control of phonon excitations in graphene
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
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.
Testing the excitability of human motoneurons
McNeil, Chris J.; Butler, Jane E.; Taylor, Janet L.; Gandevia, Simon C.
2013-01-01
The responsiveness of the human central nervous system can change profoundly with exercise, injury, disuse, or disease. Changes occur at both cortical and spinal levels but in most cases excitability of the motoneuron pool must be assessed to localize accurately the site of adaptation. Hence, it is critical to understand, and employ correctly, the methods to test motoneuron excitability in humans. Several techniques exist and each has its advantages and disadvantages. This review examines the most common techniques that use evoked compound muscle action potentials to test the excitability of the motoneuron pool and describes the merits and limitations of each. The techniques discussed are the H-reflex, F-wave, tendon jerk, V-wave, cervicomedullary motor evoked potential (CMEP), and motor evoked potential (MEP). A number of limitations with these techniques are presented. PMID:23630483
Nanoscale control of phonon excitations in graphene.
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
Quantum revivals and many-body localization
NASA Astrophysics Data System (ADS)
Moore, Joel; Vasseur, Romain; Parameswaran, Siddharth
2015-03-01
We show that the interaction-induced dephasing that distinguishes many-body localized phases from Anderson insulators has a striking consequence for quantum revivals in the time evolution of local observables. We examine the magnetization dynamics of a single ``qubit'' spin weakly coupled to an otherwise isolated disordered spin chain and first demonstrate that in the localized regime the spin chain is unable to act as a source of dissipation for the qubit, which therefore retains an imprint of its initial magnetization at infinite time. For Anderson localization, the magnetization exhibits periodic revivals, whose rate is strongly suppressed upon adding interactions after a time scale corresponding to the onset of dephasing. In contrast, the ergodic phase acts as a bath for the qubit, with no revivals visible on the time scales studied. The suppression of quantum revivals provides a quantitative, experimentally observable alternative to entanglement growth as a measure of the ``non-ergodic but dephasing'' nature of many-body localized systems.
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.
Exciting flavored bound states
NASA Astrophysics Data System (ADS)
Rojas, E.; El-Bennich, B.; de Melo, J. P. B. C.
2014-10-01
We study ground and radial excitations of flavor singlet and flavored pseudoscalar mesons within the framework of the rainbow-ladder truncation using an infrared massive and finite interaction in agreement with recent results for the gluon-dressing function from lattice QCD and Dyson-Schwinger equations. Whereas the ground-state masses and decay constants of the light mesons as well as charmonia are well described, we confirm previous observations that this truncation is inadequate to provide realistic predictions for the spectrum of excited and exotic states. Moreover, we find a complex conjugate pair of eigenvalues for the excited D(s) mesons, which indicates a non-Hermiticity of the interaction kernel in the case of heavy-light systems and the present truncation. Nevertheless, limiting ourselves to the leading contributions of the Bethe-Salpeter amplitudes, we find a reasonable description of the charmed ground states and their respective decay constants.
Global Dynamics of a Parametrically and Externally Excited Thin Plate
WEI ZHANG; ZHAOMIAO LIU; PEI YU
2001-01-01
Both the local and global bifurcations of a parametrically and externally excited simply supported rectangular thin plate are analyzed. The formulas of the thin plate are derived from the von Kármán equation and Galerkin's method. The method of multiple scales is used to find the averaged equations. The numerical simulation of local bifurcation is given. The theory of normal form,
Passivation of photocarrier recombination on CdS photoanode by two-color excitation
Nakabayashi, Seiichiro; Kira, Akira (Institute of Physical and Chemical Research, Saitama (Japan))
1990-09-20
A CdS single-crystal photoelectrode in aqueous solution containing sodium sulfite was subjected to two-color excitation. The photocurrent caused by UV excitation was markedly enhanced by simultaneous sub-bandgap excitation; no photocurrent occurred for the sub-bandgap excitation alone. The enhancement is explained in terms of passivation of a recombination center by sub-bandgap excitation. The presence of such a recombination center is supported by photocapacitance measurement. Polarized two-color excitation and electrolyte electroreflectance spectroscopy revealed that the recombination center is not localized on the uppermost surface layer but penetrates inside.
Detecting Breather Excitations with Inelastic Tunneling Spectroscopy
Jian-Xin Zhu; K. O. Rasmussen; A. R. Bishop; A. V. Balatsky
2004-07-08
We propose inelastic electron tunneling spectroscopy scanning tunneling microscopy (IETS-STM) as a means of exciting and observing intrinsic localized modes (breathers) in a macromolecule. As a demonstration, inelastic tunneling features of the density of states are calculated for a simple nonlinear elastic Morse chain. The general formalism we have developed for the IETS is applicable to other nonlinear extended objects, such as DNA on a substrate.
STM-excited luminescence on organic materials
S. F. Alvarado; L. Libioulle; P. F. Seidler
1997-01-01
A scanning tunneling microscope (STM) is used to generate electroluminescence from thin films of tris(8-hydroxyquinolato) aluminum (Alq3) deposited on Au(111) substrates. The emission spectra are highly dependent on the local structural features of the thin film. Furthermore, the intensity distribution is modulated by the collective charge-carrier excitations of the tip and the substrate. This is manifested as a red-shifted emission
Tibor Rakovszky; Janos K. Asboth
2015-05-18
Quantum walks are promising for information processing tasks because on regular graphs they spread quadratically faster than random walks. Static disorder, however, can turn the tables: unlike random walks, quantum walks can suffer Anderson localization, whereby the spread of the walker stays within a finite region even in the infinite time limit. It is therefore important to understand when we can expect a quantum walk to 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 generic 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 sets in, and the walk spreads subdiffusively. Using an efficient numerical algorithm, we calculate the bulk topological invariants of the disordered walk, and interpret the disorder-induced Anderson localization and delocalization transitions using these invariants.
Coulomb Drag for Strongly Localized Electrons: A Pumping Mechanism M. E. Raikh1
von Oppen, Felix
of Anderson local- ization [16], diffusive layers with correlated disorder [17], and double-layer systems-dimensional systems, the theories of Coulomb drag shared the common scenario of quasiparticles (electrons, holes noise. In equilibrium, the average K12 hn1tn2t i is an even function of . Suppose now
Christian Sadel
2015-06-15
We show that the Anderson model has a transition from localization to delocalization at exactly 2 dimensional growth rate on antitrees with normalized edge weights which are certain discrete graphs. The kinetic part has a one-dimensional structure allowing a description through transfer matrices which involve some Schur complement. For such operators we introduce the notion of having one propagating channel and extend theorems from the theory of one-dimensional Jacobi operators that relate the behavior of transfer matrices with the spectrum. These theorems are then applied to the considered model. In essence, in a certain energy region the kinetic part averages the random potentials along shells and the transfer matrices behave similar as for a one-dimensional operator with random potential of decaying variance. At $d$ dimensional growth for $d>2$ this effective decay is strong enough to obtain absolutely continuous spectrum, whereas for some uniform $d$ dimensional growth with $dspectrum in this energy region. At exactly uniform $2$ dimensional growth also some singular continuous spectrum appears, at least at small disorder. As a corollary we also obtain a change from singular spectrum ($d\\leq 2$) to absolutely continuous spectrum ($d\\geq 3)$ for random operators of the type $\\mathcal{P}_r \\Delta_d \\mathcal{P}_r+\\lambda \\mathcal{V}$ on $\\mathbb{Z}^d$, where $\\mathcal{P}_r$ is an orthogonal radial projection, $\\Delta_d$ the discrete adjacency operator (Laplacian) on $\\mathbb{Z}^d$ and $\\lambda \\mathcal{V}$ a random potential.
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.
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.
Charge transfer from delocalized excited states in a bulk heterojunction material
NASA Astrophysics Data System (ADS)
Kaake, Loren G.; Moses, Daniel; Heeger, Alan J.
2015-02-01
Charge generation in an organic photovoltaic blend was investigated using transient absorption spectroscopy. In films of pure electron donating material, subpicosecond spectral oscillations were observed and assigned to torsional modes associated with excited state relaxation and localization. These modes are systematically suppressed in the presence of fullerene, indicating that a significant fraction of charge transfer occurs prior to excited state localization.
Lan Ma; Chris Janetopoulos; Liu Yang; Peter N. Devreotes; Pablo A. Iglesias
2004-01-01
Chemotaxing cells, such as Dictyostelium and mammalian neutrophils, sense shallow chemoattractant gradients and respond with highly polarized changes in cell morphology and motility. Uniform chemoattractant stimulation induces the transient translocations of several downstream signaling components, including phosphoinositide 3-kinase (PI3K), tensin homology protein (PTEN), and phosphatidylinositol 3,4,5-trisphosphate (PI(3,4,5)P3). In contrast, static spatial chemoattractant gradients elicit the persistent, amplified localization of these
Charge transfer excitations from excited state Hartree-Fock subsequent minimization scheme
Theophilou, Iris, E-mail: i.theophilou@fz-juelich.de [Peter Grunberg Institut (PGI) Forschungszentrum Jülich, D-52425 Jülich (Germany)] [Peter Grunberg Institut (PGI) Forschungszentrum Jülich, D-52425 Jülich (Germany); Tassi, M.; Thanos, S. [Institute for Advanced Materials, Physicochemical Processes, Nanotechnology and Microsystems, ‘Demokritos’ National Center for Scientific Research, 15310 Athens (Greece)] [Institute for Advanced Materials, Physicochemical Processes, Nanotechnology and Microsystems, ‘Demokritos’ National Center for Scientific Research, 15310 Athens (Greece)
2014-04-28
Photoinduced charge-transfer processes play a key role for novel photovoltaic phenomena and devices. Thus, the development of ab initio methods that allow for an accurate and computationally inexpensive treatment of charge-transfer excitations is a topic that nowadays attracts a lot of scientific attention. In this paper we extend an approach recently introduced for the description of single and double excitations [M. Tassi, I. Theophilou, and S. Thanos, Int. J. Quantum Chem. 113, 690 (2013); M. Tassi, I. Theophilou, and S. Thanos, J. Chem. Phys. 138, 124107 (2013)] to allow for the description of intermolecular charge-transfer excitations. We describe an excitation where an electron is transferred from a donor system to an acceptor one, keeping the excited state orthogonal to the ground state and avoiding variational collapse. These conditions are achieved by decomposing the space spanned by the Hartree-Fock (HF) ground state orbitals into four subspaces: The subspace spanned by the occupied orbitals that are localized in the region of the donor molecule, the corresponding for the acceptor ones and two more subspaces containing the virtual orbitals that are localized in the neighborhood of the donor and the acceptor, respectively. Next, we create a Slater determinant with a hole in the subspace of occupied orbitals of the donor and a particle in the virtual subspace of the acceptor. Subsequently we optimize both the hole and the particle by minimizing the HF energy functional in the corresponding subspaces. Finally, we test our approach by calculating the lowest charge-transfer excitation energies for a set of tetracyanoethylene-hydrocarbon complexes that have been used earlier as a test set for such kind of excitations.
Singlet-triplet Hamiltonian for spin excitations in a Kondo insulator
Barabanov, A. F., E-mail: abarabanov@mtu-net.r [Russian Academy of Sciences, Institute of High-Pressure Physics (Russian Federation); Maksimov, L. A. [Moscow Institute of Physics and Technology (Russian Federation)
2010-08-15
In the nonsymmetric version of the periodic Anderson model for a Kondo insulator, an effective singlet-triplet Hamiltonian H{sub s-t} with indirect antiferromagnetic f-f exchange is constructed, which makes it possible to analyze the dynamic magnetic susceptibility {chi}{sub f}(k, {omega}) of f electrons. Hamiltonian H{sub s-t} is used to describe the experimentally observed dispersion of the three-level spin excitation spectrum in YbB{sub 12}. A distinguishing feature of this analysis is the introduction of small-radius singlet and triplet collective f-d excitations that form low- and high-lying spin bands during motion over the lattice.
NASA Astrophysics Data System (ADS)
Hasegawa, Jun-ya
2013-05-01
Solvatochromic effect in proteins and solutions was described by a configuration interaction singles (CIS) wave function with fragment-localized molecular orbitals. Coarse-grained analysis indicated that the CI wave function can be described by local excitations and charge-transfer (CT) excitations between the chromophore and the environment. We developed an atomic-orbital direct runcated CIS code and applied the excited states of retinal chromophore in bacteriorhodopsin and MeOH environments, and those of s-trans-acrolein in water. Number of excitation operators was significantly reduced by eliminating the CT excitations between the environmental fragments. The truncated CIS wave functions reproduced the original excitation energies very well.
Not Available
1992-07-01
Through a series of TABLETOP exercises and other events that involved participation by State and Federal organizations, the need was identified for further explanation of financial and other related resources available to individuals and State and local governments in a major emergency at a nuclear power plant. A group with representatives from the Nuclear Regulatory commission, the Federal Emergency Management Agency, and the American Nuclear Insurers/Mutual Atomic Energy Liability Underwriters was established to work toward this end. This report is the result of that effort. This document is not meant to modify, undermine, or replace any other planning document (e.g., the Federal Radiological Emergency Response Plan or the Federal Response Plan). Its purpose is to clarify issues that have surfaced regarding resources available under the Price-Anderson and Stafford Acts.
Zhang, David Yu
2014 Rice University / UT MD Anderson Med Into Grad Program in Translational Cancer Diagnostics & Therapeutics Research for Bioengineers & Biophysicists Program Details: Rice University and The University Research for Bioengineers and Biophysicists. Doctoral students from Rice's Bioengineering, Biochemistry
Zhang, Jiangwei; Liu, Zhenhua; Huang, Yichao; Zhang, Jin; Hao, Jian; Wei, Yongge
2015-05-19
The ?2-O atom in Anderson polyoxometalates was regioselectively activated by the introduction of protons, which, upon functionalization with triol ligands, could afford a series of unique ? isomers of the organically-derived Anderson cluster {[RCC(CH2O)3]MMo6O18(OH)3}(3-). Herein proton-controlled isomer transformation between the ? and ? isomer was observed by using the fingerprint region in the IR spectra and (13)C NMR spectra. PMID:25959667
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.
Excitation of magnetic dipole transitions at optical frequencies.
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 Y_{2}O_{3} 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
BROADBAND EXCITATION IN NUCLEAR MAGNETIC RESONANCE
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.
Effective models for Anderson impurity and Kondo problems from continuous unitary transformations
NASA Astrophysics Data System (ADS)
Krones, Jörn; Uhrig, Götz S.
2015-03-01
The method of continuous unitary transformations (CUTs) is applied to the Anderson impurity and the Kondo model aiming at the systematic derivation of convergent effective models. If CUTs are applied in a conventional way, diverging differential equations occur. Similar to poor man's scaling, the energy scale, below which the couplings diverge, corresponds to the Kondo temperature TK. We present a way to apply CUTs to the Kondo and to the Anderson impurity model so that no divergences occur but a converged effective low-energy model is derived with small finite parameters at arbitrarily small energies. The ground state corresponds to a bound singlet with a binding energy given by the Kondo temperature TK.
Magnetostrictive resonance excitation
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.
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.
Pulse excitation of bolometer bridges
NASA Technical Reports Server (NTRS)
Rusk, S. J.
1972-01-01
Driving bolometer bridge by appropriately phased excitation pulses increases signal-to-noise ratio of bolometer sensor which operates on a chopped light beam. Method allows higher applied voltage than is possible by conventional ac or dc excitation.
Anderson–Stuart model to analyze conductivity of fluormica glass-ceramics
Mahantappa S Jogad
2002-01-01
AC and DC conductivities have been measured in glass-ceramics (GC) at different temperatures in the range 298–628 K and in the frequency range 100 Hz–5 MHz. Using the Anderson–Stuart model, we have calculated the activation energy, which is observed to be lower than that of the DC conductivity. The analysis for glass-ceramics indicates that the conductivity variation with frequency exhibits
Ferromagnetic instability in a mean-field slave-boson approach for the Anderson lattice
Dorin, V.; Schlottmann, P. (Department of Physics and Center for Materials Research and Technology, Florida State University, Tallahassee, Florida 32306 (United States))
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.
ACCURACY OF THE BRCAPRO RISK ASSESSMENT MODEL IN MALES PRESENTING TO MD ANDERSON FOR BRCA TESTING
Carolyn Garby; Arun Banu M. D; Jackson Michelle M. S. CGC; Litton Jennifer M. D; HashmiSyed M. D; Giordano Sharon M. D MPH; Singletary Claire M. S CGC
2012-01-01
ACCURACY OF THE BRCAPRO RISK ASSESSMENT MODEL IN MALES PRESENTING TO MD ANDERSON FOR BRCA TESTING\\u000aPublication No. _______\\u000aCarolyn A. Garby, B.S.\\u000aSupervisory Professor: Banu Arun, M.D.\\u000aHereditary Breast and Ovarian Cancer (HBOC) syndrome is due to mutations in BRCA1 and BRCA2 genes. Women with HBOC have high risks to develop breast and ovarian cancers. Males with HBOC are
Solution of the multichannel Anderson impurity model: Ground state and thermodynamics
C. J. Bolech; N. Andrei
2005-01-01
We present the solution of the SU(N)?SU(M) Anderson impurity model using the Bethe-Ansatz. We first explain what extensions to the formalism were required for the solution. Subsequently we determine the ground state and derive the thermodynamics over the full range of temperature and fields. We identify the different regimes of valence fluctuation at high temperatures, followed by moment formation or
Variational ground state for the periodic Anderson model with an indirect hybridization
Zheng Hang
1987-01-01
As the direct on-site hybridization is forbidden by inversion symmetry in most of the mixed-valence compounds, an indirect on-site hybridization mediated by phonons has been introduced into the periodic Anderson model to constitute our model system. Then we try to construct a variational ground state for the model Hamiltonian by the following steps. First, we develop a new procedure to
Harmonically excited orbital variations
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.
Temperature and excitable cells
Fillafer, Christian; Schneider, Matthias F
2013-01-01
Temperature affects a host of biological processes, one of which is the conduction velocity of action potentials (AP). The velocity-temperature profile of APs has remained remarkably conserved across excitable animal and plant cells. Herein, we will not analyze this behavior in terms of temperature sensitivities of single molecules (e.g., ion channels), but rather we present a phenomenological thermodynamic interpretation. By assuming that APs are acoustic phenomena, one arrives at testable predictions about the temperature-dependence of the macroscopic material properties of the excitable cell membrane. These material properties set constraints on the excitability of a cell membrane and allow us to hypothesize about its typical relaxation timescales. The presented approach—by virtue of its thermodynamic nature—is by no means limited to temperature. It applies equally well to all thermodynamic variables (e.g., mechanical stretch, pH, ion concentrations, etc.) and to underline this argument we discuss some implications and predictions for sensory physiology. PMID:24563710
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.
Get excited: reappraising pre-performance anxiety as excitement.
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
Localization for a Nonlinear Sigma Model in a Strip Related to Vertex Reinforced Jump Processes
NASA Astrophysics Data System (ADS)
Disertori, Margherita; Merkl, Franz; Rolles, Silke W. W.
2014-12-01
We study a lattice sigma model which is expected to reflect Anderson localization and delocalization transition for real symmetric band matrices in 3D, but describes the mixing measure for a vertex reinforced jump process too. For this model we prove exponential localization at any temperature in a strip, and more generally in any quasi-one dimensional graph, with pinning (mass) at only one site. The proof uses a Mermin-Wagner type argument and a transfer operator approach.
Search for Gluonic Excitations
Paul Eugenio
2007-10-01
Studies of meson spectra via strong decays provide insight regarding QCD at the confinement scale. These studies have led to phenomenological models for QCD such as the constituent quark model. However, QCD allows for a much richer spectrum of meson states which include extra states such as exotics, hybrids, multi-quarks, and glueballs. First discussion of the status of exotic meson searches is given followed by a discussion of plans at Jefferson Lab to double the energy of the machine to 12 GeV, which will allow us to access photoproduction of mesons in search for gluonic excited states.
Search for Gluonic Excitations
Eugenio, Paul [Florida State University, Department of Physics, Tallahassee, Florida 32306 (United States)
2007-10-26
Studies of meson spectra via strong decays provide insight regarding QCD at the confinement scale. These studies have led to phenomenological models for QCD such as the constituent quark model. However, QCD allows for a much richer spectrum of meson states which include extra states such as exotics, hybrids, multi-quarks, and glueballs. First discussion of the status of exotic meson searches is given followed by a discussion of plans at Jefferson Lab to double the energy of the machine to 12 GeV, which will allow us to access photoproduction of mesons in search for gluonic excited states.
NSDL National Science Digital Library
The Concord Consortium
2011-12-13
Investigate how atoms can be excited to give off radiation (photons) with models of electron energy diagrams. Explore the effects of energy levels in atoms through interactive computer models. Learn about the different electron orbitals of an atom, and explore three-dimensional models of the atoms. Learn about photons and why they are emitted, and gain an understanding of the link between energy levels and photons as you discover how an atom?s electron configuration affects which wavelengths of light it will admit or absorb.
Electronic excitation as a mode of heat dissipation in laser-driven cluster plasmas
NASA Astrophysics Data System (ADS)
Rajeev, R.; Rishad, K. P. M.; Madhu Trivikram, T.; Krishnamurthy, M.
2013-12-01
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 CO2, 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.
Cobo, Marcio Fernando; Reichert, Detlef; Saalwächter, Kay; deAzevedo, Eduardo Ribeiro
2014-11-01
A composed Gaussian local field is proposed to describe the effect of molecular motions on NMR signals of SIn units (e.g., CHn or NHn), based upon the well-know Anderson-Weiss (AW) approximation. The approach is exemplified on constant-time recoupled dipolar chemical-shift correlation (tC-recDIPSHIFT) experiments, providing an analytical formula that can be used as a fitting function in studies of intermediate-regime motions. By comparison of analytical tC-recDIPSHIFT curves and dynamic spin dynamics simulations, we show that for heteronuclear spin pairs (SI system), the AW treatment assuming the usual Gaussian local field is accurate. However, the approximation fails for the case of SIn spin systems for motional rates higher than a few kHz. Based on earlier work of Terao et al., who proposed a decomposition of CHn dipolar powder patterns into to 2(n) spin-pair-type patterns, we propose an AW approach based upon a double-Gaussian local field. We derive an analytical formula for tC-recDIPSHIFT signals, and demonstrate its accuracy by comparison with simulations of several motional geometries and rates, and with experimental results for a model sample. The approach is not limited to the tC-recDIPSHIFT experiment and should be of general use in dipolar-coupling based experiments probing (partially) mobile SIn molecular moieties. PMID:25442780
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,
Hybrid excitation synchronous generators for island operation
K. Kamiev; J. Nerg; J. Pyrho?nen; V. Zaboin
2010-01-01
The paper discusses Hybrid Excitation Synchronous Machines (HESMs) principles and their application possibilities. HESMs combine both features of traditional wound field synchronous machines (SMs) and permanent magnet synchronous machines (PMSMs). Such electrical machines have two different rotor excitation sources: PM excitation and wound field excitation. The wound field excitation is used to control the excitation flux in the air gap,
... disease has gone into remission. Does Localized Scleroderma Go Away? As a general rule, localized scleroderma is ... disease has gone into remission. Does Localized Scleroderma Go Away? As a general rule, localized scleroderma is ...
NASA Astrophysics Data System (ADS)
Mead, Roy D.
This dissertation describes high-resolution tunable laser photodetachment studies of both valence and dipole -bound excited states of negative ions. Also discussed is a merged laser-ion beam photodetachment spectrometer. The photodetachment cross section of C(,2)('-) displays many sharp resonances, due to excitation of autodetaching levels of the B('2)(SIGMA)(,u)('+) valence state lying above the onset of the (C(,2) + e) continuum. The positions of approximately 1,000 resonances were measured, allowing the spectroscopic constants of the ground X('2)(SIGMA)(,g)('+) and excited B('2)(SIGMA)(,u)('+) states to be determined, including spin-rotation constants. The previously unobserved A('2)(PI)(,u) state has been characterized by deperturbation analysis. Strong A-X transitions are predicted near 2.5 microns. The widths of C(,2)('-) resonances with v = 6 -10 and J = 1-60 have also been measured, providing autodetachment rates as a function of both rotation and vibration, ranging from 10('8) to 10('11) s('-1). The first conclusive observation of an entirely new class of states, called dipole-bound or dipole-supported states, is discussed for the case of acetaldehyde enolate (vinyl oxide) negative ion. In these novel states, the extra electron is weakly bound ((TURN)5 cm('-1)) in a very diffuse orbital ((TURN)100 (ANGSTROM)) by the dipole moment of the neutral core. Weak electric fields (< 70 V/cm) are found to rapidly detach the dipole-bound electron. These dipole-bound states resemble Rydberg states of neutrals, but differ from Rydbergs in many important respects. They should be present for all neutrals with dipole moments > 2 Debye. The merged laser-ion beam (also known as coaxial -beams) spectrometer has 0.0005 cm('-1) resolution in the visible region, simultaneously achieving very high sensitivity. It employs quadrupole beam deflectors to merge and laser and negative ion beams, and can scan spectra either by scanning the laser frequency or the Doppler shift of the ion beam. Both electrons and neutral photodetachment products are detected. Even very low energy electrons (< 20 meV) are collected and counted, and the collector may be adjusted to collect either all electrons or only low energy electrons as needed.
Parity-dependent localization in N strongly coupled chains
NASA Astrophysics Data System (ADS)
Weinmann, Dietmar; Evangelou, S. N.
2014-10-01
Anderson localization of wave functions at zero energy in quasi-one-dimensional (1D) systems of N disordered chains with interchain coupling t is examined. Localization becomes weaker than for the 1D disordered chain (t =0) when t is smaller than the longitudinal hopping t'=1, and localization becomes usually much stronger when t ?t'. This is not so for all N. We find "immunity" to strong localization for open (periodic) lateral boundary conditions when N is odd (a multiple of 4), with localization that is weaker than for t =0 and rather insensitive to t when t ?t'. The peculiar N dependence and a critical scaling with N are explained by a perturbative treatment in t'/t, and the correspondence to a weakly disordered effective chain is shown. Our results could be relevant for experimental studies of localization in photonic waveguide arrays.
Neuromorphic excitable maps for visual processing.
Rasche, Christoph
2007-03-01
An excitable membrane is described which can perform different visual tasks such as contour detection, contour propagation, image segmentation, and motion detection. The membrane is designed to fit into a neuromorphic multichip system. It consists of a single two-dimensional (2-D) layer of locally connected integrate-and-fire neurons and propagates input in the subthreshold and the above-threshold range. It requires adjustment of only one parameter to switch between the visual tasks. The performance of two spiking membranes of different connectivity is compared, a hexagonally and an octagonally connected membrane. Their hardware and system suitability is discussed. PMID:17385636
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.
Fusion excitation function revisited
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.
Causation's nuclear future: applying proportional liability to the Price-Anderson Act.
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
Causation's nuclear future: applying proportional liability to the Price-Anderson Act.
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
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.
Metastable Quasimolecules in Excited Gases
V. N. Malnev; R. A. Naryshkin
2008-09-09
Quasimolecules, which consist of two differently excited atoms in a resonantly excited gas, are considered. The energy of dissociation and typical sizes of such molecules are calculated in the first order of quantum-mechanical perturbation theory with the help of the dipole-dipole interaction operator. It is shown that there exist metastable quasimolecules, whose dipole radiative transition to the ground state (two non-excited atoms) is forbidden. The lifetime of such molecules is estimated and it is shown that quasimolecules may considerably affect the transport processes in a resonantly excited gas.
Machine learning for many-body physics: The case of the Anderson impurity model
NASA Astrophysics Data System (ADS)
Arsenault, Louis-François; Lopez-Bezanilla, Alejandro; von Lilienfeld, O. Anatole; Millis, Andrew J.
2014-10-01
Machine learning methods are applied to finding the Green's function of the Anderson impurity model, a basic model system of quantum many-body condensed-matter physics. Different methods of parametrizing the Green's function are investigated; a representation in terms of Legendre polynomials is found to be superior due to its limited number of coefficients and its applicability to state of the art methods of solution. The dependence of the errors on the size of the training set is determined. The results indicate that a machine learning approach to dynamical mean-field theory may be feasible.
NASA Astrophysics Data System (ADS)
Vaucher, Gail T.; Vaucher, Christopher A.; Walters, Donald L.
1991-01-01
From 13 to 19 November 1989, the Naval Postgraduate School Atmospheric Optics Group acquired atmospheric optical turbulence measurements at the 31-inch Lowell Observatory telescope dome facility on Anderson Mesa, 16 km southeast of Flagstaff, Arizona. The parameters measured, the transverse coherence length and the isoplanatic angle, were part of an ongoing site survey for a large-scale, ground-based, synthetic aperture system (100 to 300 m baseline stellar interferometer). This report compiles, analyses and summarizes the acquired optical data. Also discussed are the synoptic meteorological events present during the data acquisition period.
Exponential scaling limit of the single-particle Anderson model via adaptive feedback scaling
Victor Chulaevsky
2015-03-09
We propose a reformulation of the bootstrap version of the Multi-Scale Analysis (BMSA), developed by Germinet and Klein, to make explicit the fact that BMSA implies asymptotically exponential decay of eigenfunctions (EFs) and of EF correlators (EFCs), in the lattice Anderson models with diagonal disorder, viz. with an IID random potential. We also show that the exponential scaling limit of EFs and EFCs holds true for a class of marginal distributions of the random potential with regularity lower than H\\"older continuity of any positive order.
Coupling Mediated Coherent Control of Localized Surface Plasmon Polaritons.
Zeuner, Franziska; Muldarisnur, Mulda; Hildebrandt, Andre; Förstner, Jens; Zentgraf, Thomas
2015-06-10
We investigate the phase-dependent excitation of localized surface plasmon polaritons in coupled nanorods by using nonlinear spectroscopy. Our design of a coupled three-nanorod structure allows independent excitation with cross-polarized light. Here, we show that the excitation of a particular plasmon mode can be coherently controlled by changing the relative phase of two orthogonally polarized light fields. Furthermore, we observe a phase relation for the excitation that is dominantly caused by damping effects. PMID:25978694
Collective Dynamics for Network-Organized Identical Excitable Nodes
NASA Astrophysics Data System (ADS)
Tao, Yu-Cheng; Cui, Ming-Zhu; Li, Hai-Hong; Yang, Jun-Zhong
2015-02-01
We investigate the collective dynamics of network-organized identical excitable nodes. We theoretically analyze the stability of the rest state and propose that there are two different transition paths: the stationary path and the oscillatory path. We find that, although the onset of collective dynamics strongly depend on the network topology, the local dynamics and how local nodes interact with each other decide the transition path and the involved bifurcation.
Anderson-Gruneisen parameter under high temperature in (Fe,Mn,Co,Mg)2SiO4
NASA Astrophysics Data System (ADS)
Gupta, S.; Goyal, S. C.
2012-07-01
The Anderson-Grüneisen parameter (?) is of considerable importance to Earth scientists because it sets limitations on the thermo-elastic properties of the lower mantle and core. However, there are several formulations on the Grüneisen parameter, which are in frequent use and predict varying dependence of d as a function of temperature. In this paper, the expressions for thermal expansion, thermal expansion coefficients and bulk modulus are obtained considering the anharmonic dependence on temperature and are applied to study these constants to (Fe,Mn,Co,Mg)2SiO4. Using the derived expressions, we have shown that different parameters on which the Anderson-Grüneisen parameter (?) depends are temperature dependent, but above all the Anderson-Grüneisen parameter (?) is independent of temperature. The results obtained have been found to be comparable to experimental data.
ANDERSON-TEIXEIRA FINAL PROOF.DOCX (DO NOT DELETE) 3/7/2011 9:29 AM DO BIOFUELS LIFE CYCLE
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
The excitation of geodesic acoustic mode flows by a resonant magnetic field and by resonant heating
Kleva, Robert G.; Hassam, A. B. [Institute for Research in Electronics and Applied Physics, University of Maryland, College Park, Maryland 20742-3511 (United States)
2013-03-15
Toroidal magnetohydrodynamic (MHD) simulations demonstrate that sheared poloidal flows in tokamaks can be generated by the resonant excitation of the geodesic acoustic mode (GAM). Poloidal flows are generated by two resonant excitation methods: oscillating currents in an external coil and an oscillating heat source. The coil current and the heat source oscillate in time at the local GAM frequency. The sheared poloidal flow generated by the excitation of the GAM may be useful for the suppression of plasma instabilities.
Analysis of polyphase brushless exciter
Xiaochuan Jia; Jih-Sheng Jason Lai; Byeong-Mun Song
2000-01-01
This paper presents modeling and simulation of the operation of an 11 phase brushless exciter. The analytical method is based on Kron's tensor method, which is developed for dealing efficiently with the time-varying topology of an exciter circuit during a digital computer solution. The inductances, which are variable with rotor position, are calculated by the 2-D FEM method. The detailed
High-energy spin and charge excitations in electron-doped copper oxide superconductors.
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
High-energy spin and charge excitations in electron-doped copper oxide superconductors
NASA Astrophysics Data System (ADS)
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.
2014-04-01
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.
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.
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.
Hoagland, H.; Crozier, W. J.
1931-01-01
Rotation of an inclined surface on which Helix is creeping straight upward, such that the axis of the animal is turned at a right angle to its previous position, but in the same plane, leads to negatively geotropic orientation after a measurable latent period or reaction time. The duration of the latent period is a function of the slope of the surface. The magnitude of the standard deviation of the mean latent period is directly proportional to the mean latent period itself, so that the relative variability of response is constant. The dependence of reaction time upon extent of displacement from symmetrical orientation in the gravitational field is found also by tilting the supporting surface, without rotation in the animal's own plane. On slopes up to 55°, the relation between latent period and the sine of the slope is hyperbolic; above this inclination, the latent period sharply declines. This change in the curve is not affected by the attachment of moderate loads to the snail's shell (up to 1/3 of its own mass), and is probably a consequence of loss of passive stable equilibrium when rotated. When added loads do not too greatly extend the snail's anterior musculature, the latent period for the geotropic reaction is decreased, and, proportionately, its ?. These facts are discussed from the standpoint that geotropic excitation in these gasteropods is due to impressed muscle-tensions. PMID:19872624
Spatio-temporal dynamics of optically excited excitonic wavepackets in semiconductor quantum wells
S. Kuckenburg; A. Knorr; S. W. Koch
2000-01-01
Optical excitation of a semiconductor quantum well leads to a built up of coherent polarization as well as charge carrier densities in the valence and conduction band. Ultrashort and spatially localized optical pulses make it possible to study the preparation, propagation and scattering of carrier wavepackets. Recent work has investigated the electronic transport phenomena for above bandedge excitation under the
Frequency-selective induction of excitation waves near sub- and supercritical Hopf bifurcation
Gerold Baier; Markus Müller
2004-01-01
We study diffusively coupled excitable systems where local perturbations induces propagation waves only within finite frequency bands. Resonance-associated complex wave trains are found for parameters fixed near the subcritical Hopf bifurcation, and crisis-associated regular spiking near a supercritical Hopf bifurcation. Whereas in the subcritical case the qualitative excitation pattern of the coupled system is similar to that of an individual
Noise-sustained oscillation and synchronization of excitable media with stirring
Neufeld, Z. (Zoltan); Zhou, C. (Changsong); Kurths, J. (Jürgen),; Kiss, I. Z.
2004-01-01
Constructive effects of noise have been well studied in spatially extended systems. In most of these studies, the media are static, reaction-diffusion type, and the constructive effects are a consequence of the interplay between local excitation due to noise perturbation and propagation of excitation due to diffusion. Many chemical or biological processes occur in a fluid environment with mixing. In this paper, we investigate the interplay among noise, excitability, diffusion and mixing in excitable media advected by a chaotic flow, in a 2-d Fitz Hugh-Nagumo model described by the reaction-advection-diffusion equations. Without stirring, noise can only generate non-coherent excited patches of the static media. In the presence of stirring, we can observe three dynamical and pattern formation regimes: (i) Non-coherent excitation, when mixing is not strong enough to achieve synchronization of independent excitations developed at different locations; (ii) Coherent global excitation, when noise-perturbation survives the mixing to generate a synchronized excitation of the whole domain; and (iii) Homogenization, when strong enough stirring dilutes quickly those noise-induced local excitations. In the presence of an external sub-threshold periodic forcing, the period of-the noise-sustained oscillations can be locked by the forcing period with different ratios. Our results may be verified in experiments and find applications in population dynamics of oceanic ecological systems.
Excitation of Er{sup 3+} ions in SiO{sub 2} with Si nanocrystals
Prokofiev, A. A. [Russian Academy of Sciences, Ioffe Physicotechnical Institute (Russian Federation)], E-mail: LXPRO@mail.ioffe.ru; Moskalenko, A. S. [Martin-Luther-Universitaet Halle-Wittenberg, Institut fuer Physik (Germany); Yassievich, I. N. [Russian Academy of Sciences, Ioffe Physicotechnical Institute (Russian Federation)
2008-08-15
Probabilities of excitation of erbium ions via Coulomb interaction with carriers localized in silicon nanocrystals embedded in SiO{sub 2}, in recombination and intraband relaxation of these carriers, have been calculated.
Opioids Excite Dopamine Neurons by Hyperpolarization of Local Interneurons
S. W. Johnson; R. A. North
1992-01-01
Increased activity of dopamine-containing neurons in the ventral tegmental area is necessary for the reinforcing ef- fects of opioids and other abused drugs. Intracellular re- cordings from these cells in slices of rat brain in vitroshowed that opioids do not affect the principal (dopamine-contain- ing) neurons but hyperpolarize secondary (GABA-contain- ing) interneurons. Experiments with agonists and antago- nists selective for
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.
Dynamic patterns and their interactions in networks of excitable elements
NASA Astrophysics Data System (ADS)
Gong, Pulin; Steel, Harrison; Robinson, Peter; Qi, Yang
2013-10-01
Formation of localized propagating patterns is a fascinating self-organizing phenomenon that happens in a wide range of spatially extended, excitable systems in which individual elements have resting, activated, and refractory states. Here we study a type of stochastic three-state excitable network model that has been recently developed; this model is able to generate a rich range of pattern dynamics, including localized wandering patterns and localized propagating patterns with crescent shapes and long-range propagation. The collective dynamics of these localized patterns have anomalous subdiffusive dynamics before symmetry breaking and anomalous superdiffusive dynamics after that, showing long-range spatiotemporal coherence in the system. In this study, the stability of the localized wandering patterns is analyzed by treating an individual localized pattern as a subpopulation to develop its average response function. This stability analysis indicates that when the average refractory period is greater than a certain value, there are too many elements in the refractory state after being activated to allow the subpopulation to support a self-sustained pattern; this is consistent with symmetry breaking identified by using an order parameter. Furthermore, in a broad parameter space, the simple network model is able to generate a range of interactions between different localized propagating patterns including repulsive collisions and partial and full annihilations, and interactions between localized propagating patterns and the refractory wake behind others; in this study, these interaction dynamics are systematically quantified based on their relative propagation directions and the resultant angles between them before and after their collisions. These results suggest that the model potentially provides a modeling framework to understand the formation of localized propagating patterns in a broad class of systems with excitable properties.
KÃ¶nig, Wolfgang
EIGENVALUE FLUCTUATIONS FOR LATTICE ANDERSON HAMILTONIANS MAREK BISKUP1, RYOKI FUKUSHIMA2. Biskup, R. Fukushima and W. KÃ¶nig. Reproduction, by any means, of the entire article for non-commercial purposes is permitted without charge. 1 #12;2 BISKUP, FUKUSHIMA, KÃ?NIG where (d) is the standard lattice
KÃ¶nig, Wolfgang
EIGENVALUE FLUCTUATIONS FOR LATTICE ANDERSON HAMILTONIANS MAREK BISKUP 1 , RYOKI FUKUSHIMA 2. Fukushima and W. KÃ¶nig. Reproduction, by any means, of the entire article for nonÂcommercial purposes is permitted without charge. 1 #12; 2 BISKUP, FUKUSHIMA, KÃ?NIG where # (d) is the standard lattice Laplacian
R. C. Anderson; C. M. Bartlett
1996-01-01
Skrjabinoclava inornatae Wong & Anderson, 1987 was found in one of five adult greater yellowlegs Tringa melanoleuca collected near Framboise, Cape Breton, Nova Scotia, Canada. This is the first report of a member of the genus in this host. The infection is regarded as sporadic and a further indication that the host distribution of members of Skrjabinoclava may be determined
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…
Rinard, Martin
Hierarchical Concurrency in Jade Daniel J. Scales, Martin C. Rinard, Monica S. Lam, and Jennifer M. Anderson Computer Systems Laboratory Stanford University, CA 94305 Abstract Jade is a data, or C++. A Jade programmer simply augments the program with assertions specify ing how the program
Collisional damping of plasma waves on a pure electron plasma column M. W. Anderson and T. M. O'Neil
California at San Diego, University of
Collisional damping of plasma waves on a pure electron plasma column M. W. Anderson and T. M. O of electron plasma waves or TrivelpieceGould waves on a pure electron plasma column is discussed. The damping in a pure electron plasma differs from that in a neutral plasma, since there are no ions to provide
A Conceptual Knowledge-link model for supporting Dental Implant Anderson Luis Szejka1,2,a
Boyer, Edmond
A Conceptual Knowledge-link model for supporting Dental Implant Process Anderson Luis Szejka1,2,a.rudek@pucpr.br, dherve.panetto@univ-lorraine.fr. Keywords: Knowledge-link. Medical Image Processing. Dental Implant visualization of CT images to define the parameters for dental implant process leaving to the dentist discretion
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
A. A. Kasim; M. K. Al-Sadoon; Y. R. Al-Shawa
1993-01-01
Eimeria scinci Phisalix 1923, is redescribed from the gall bladder of six of 20 (30%) specimens of the sandfish lizard, Scincus mitranus Anderson 1871 from Zulfi in the central region of Saudi Arabia. This report represents a new host and geographic record for the parasite. Oocyst measurements were similar to those reported previously from Scincus officinalis Laurenti 1768 in Tunisia.
Cicirello, Vincent A.
Intelligent Systems Demonstration: The Secure Wireless Agent Testbed (SWAT) Gustave Anderson Chestnut Street Philadelphia, PA 19104 Abstract We will demonstrate the Secure Wireless Agent Testbed (SWAT for next-generation wireless mobile agent systems. SWAT is an implemented system that fully integrates: 1
3. Discussion by T. Van Gestel, B. De Moor, B.D.O. Anderson and P. Van Overschee
endorse their other comments. References [1] D.F. Enns, Model reduction for control system design, Ph3. Discussion by T. Van Gestel, B. De Moor, B.D.O. Anderson and P. Van Overschee Frequency weighted balancing [1] is an important technique with interpretations and ap- plications in system identification
Ion-temperature-gradient modes in stellarator geometry (T Rafiq, J Anderson, M Nadeem and M Persson)
Ion-temperature-gradient modes in stellarator geometry (T Rafiq, J Anderson, M Nadeem and M Persson Göteborg, Sweden) The stability of the ion-temperature gradient mode has been examined in the short calculations have been presented on field line of reference at $\\theta =\\zeta =0$ on the magnetic surface $s=0
Goldschmidt, Christina
UModelling Leaf Shape Evolution Jotun Hein, Nick Jones, Miltos Tsiantis, James Anderson and John on simple models of shape evolution and their application to leaf shapes. Shape analysis is a well in the Tsiantis group (Piazza et al, 2010; Hay and Tsiantis, 2006). Leaf shape can be described as simple
Importance of considering helium excited states in He+ scattering by an aluminum surface
NASA Astrophysics Data System (ADS)
Iglesias-García, A.; García, Evelina A.; Goldberg, E. C.
2014-11-01
The He+/Al system is a very interesting projectile-surface combination which was thought initially as an example of a pure Auger neutralization mechanism. Then, because of the measured reionization explained by the antibonding interaction of the projectile state with the core target states, the resonant charge exchange with the band states was considered as another important contribution to the neutralization. Nevertheless, by only considering the neutralization to the ground state of helium, the measured ion survival probability is still overestimated. On the other hand, measurements of electron emission from an Al surface bombarded by He positive ions suggested the possibility of occupied excited states of helium due to the ion-surface collision. In this work, we also include the excited states of He within the time-dependent scattering process in which both neutralization mechanisms, resonant and Auger, are simultaneously contemplated. Our starting point is a multiorbital Anderson Hamiltonian projected over the selected space of ground and excited atomic configurations. An extra term related to the Auger mechanism is added to this Hamiltonian. A difference with previous works is that this approach includes the electron spin and, therefore, the spin fluctuation statistics in the charge-exchange process is correctly taken into account. We find a notable improvement in the agreement with the experiments and also that the interference between both mechanisms is not dramatic.
Industrial applications of photonuclear resonance excitation
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 ...
Rosnes, Mali H; Yvon, Carine; Long, De-Liang; Cronin, Leroy
2012-09-01
A comprehensive study of the isomer-independent synthesis of TRIS ((HOCH(2))(3)CNH(2)) Mn-Anderson compounds from Na(2)MoO(4)·2H(2)O, via the corresponding octamolybdate species, is presented. Three octamolybdate salts of [Mo(8)O(26)](4-) in the ?-isomer form, with tetramethylammonium (TMA), tetraethylammonium (TEA) and tetrapropylammonium (TPA) as the counter cation, were synthesised from the sodium molybdate starting material. Fine white powdery products for the three compounds were obtained, which were fully characterised by elemental analysis, TGA, solution and solid state Raman, IR and ESI-MS, revealing a set ratio of Na and organic cations for each of the three compounds; (TMA)(2)Na(2)[Mo(8)O(26)] (1), (TEA)(3)Na(1)[Mo(8)O(26)] (2) and (TPA)(2)Na(2)[Mo(8)O(26)] (3), and the analyses also confirmed that the three compounds all consisted of the octamolybdate in the ?-isomeric form. ESI-MS analyses of 1, 2 and 3 show similar fragmentation for these ?-isomers compared to the previously reported study for the ?-isomer ((TBA)(4)[?-Mo(8)O(26)]) (A) in the synthesis of ((TBA)(3)[MnMo(6)O(18)((OCH(2))(3)CNH(2))(2)]) (B), and compounds 1, 2 and 3 were successfully used to synthesise equivalent TRIS Mn-Anderson compounds: (TMA)(3)[MnMo(6)O(18)((OCH(2))(3)CNH(2))(2)] (4), (TEA)(3)[MnMo(6)O(18)((OCH(2))(3)CNH(2))(2)] (5) and (TPA)(2)Na(1)[MnMo(6)O(18)((OCH(2))(3)CNH(2))(2)] (6), as well as Na(3)[MnMo(6)O(18)((OCH(2))(3)CNH(2))(2)] (7). This is the first example where symmetric organically-grafted Mn-Anderson compounds have been synthesised in DMF from anything but the {Mo(8)O(26)} ?-isomer. PMID:22825595
Recanati, Catherine
proposed to understand certain metal- insulator transitions, is now considered an ubiquitous phenomenon transport associated with incoherent wave scattering [4]. So far, AL has been reported for light waves in di
proposed to understand certain metal- insulator transitions, is now considered an ubiquitous phenomenon transport associated with incoherent wave scattering [4]. So far, AL has been reported for light waves
Bragg grating writing in acoustically excited optical fiber
NASA Astrophysics Data System (ADS)
Oliveira, Roberson A.; Cook, Kevin; Canning, John; Pohl, Alexandre A. P.
2010-07-01
The inscription of Bragg gratings in optical fiber under acoustic excitation is proposed and demonstrated. A permanent change in the refractive index as the period of the grating is modulated with periodic acoustic excitation during UV grating writing leads to sampling of the structure and the production of spectral combs. A physical contribution to index change through stress profiling reveals a complicated picture of UV-induced index change, well beyond simple localized defect and structural changes. The method offers the potential for tuning and tailoring conventional uniform gratings during the writing process using adjustable acoustic wave functions, an approach to control the writing process.
Parametric Excitation of a DWSC
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...
Collisional excitation of interstellar formaldehyde
NASA Technical Reports Server (NTRS)
Green, S.; Garrison, B. J.; Lester, W. A., Jr.; Miller, W. H.
1978-01-01
Previous calculations for rates of excitation of ortho-H2CO by collisions with He have been extended to higher rotational levels and kinetic temperatures to 80 K. Rates for para-H2CO have also been computed. Pressure-broadening widths for several spectral lines have been obtained from these calculations and are found to agree with recent data within the experimental uncertainty of 10%. Excitation of formaldehyde by collisions with H2 molecules is also discussed.
Two-photon excitation photodynamic therapy with Photofrin
NASA Astrophysics Data System (ADS)
Karotki, Aliaksandr; Khurana, Mamta; Lepock, James R.; Wilson, Brian C.
2005-09-01
Photodynamic therapy (PDT) based on simultaneous two-photon (2-?) excitation has a potential advantage of highly targeted treatment by means of nonlinear localized photosensitizer excitation. One of the possible applications of 2-? PDT is a treatment of exodus age-related macular degeneration where highly targeted excitation of photosensitizer in neovasculature is vital for reducing collateral damage to healthy surrounding tissue. To investigate effect of 2-? PDT Photofrin was used as an archetypal photosensitizer. First, 2-? absorption properties of Photofrin in the 750 - 900 nm excitation wavelength range were investigated. It was shown that above 800 nm 2-? interaction was dominant mode of excitation. The 2-? cross section of Photofrin was rather small and varied between 5 and 10 GM (1 GM = 10-50 cm4s/photon) in this wavelength range. Next, endothelial cells treated with Photofrin were used to model initial effect of 2-? PDT on neovasculature. Ultrashort laser pulses provided by mode-locked Ti:sapphire laser (pulse duration at the sample 300 fs, repetition rate 90 MHz, mean laser power 10 mW, excitation wavelength 850 nm) were used for the excitation of the photosensitizer. Before 2-? excitation of the Photofrin cells formed a single continuous sheet at the bottom of the well. The tightly focused laser light was scanned repeatedly over the cell layer. After irradiation the cell layer of the control cells stayed intact while cells treated with photofrin became clearly disrupted. The light doses required were high (6300 Jcm(-2) for ~ 50% killing), but 2-? cytotoxicity was unequivocally demonstrated.
NASA Technical Reports Server (NTRS)
Goshchitskii, B. N.; Davydov, S. A.; Karkin, A. E.; Mirmelstein, A. V.; Sadovskii, M. V.
1990-01-01
Theoretical interpretation of recent experiments on radiationally disordered high-temperature superconductors is presented, based on the concepts of mutual interplay of Anderson localization and superconductivity. Microscopic derivation of Ginzburg-Landau coefficients for the quasi-two-dimensional system in the vicinity of localization transition is given in the framework of the self-consistent theory of localization. The 'minimal metallic conductivity' for the quasi-two-dimensional case is enhanced due to a small overlap of electronic states on the nearest neighbor conducting planes. This leads to a stronger influence of localization effects than in ordinary (three-dimensional) superconductors. From this point of view even the initial samples of high-temperature superconductors are already very close to Anderson transition. Anomalies of H(c2) are also analyzed, explaining the upward curvature of H(c2)(T) and apparent independence of dH(c2)/dT (T = T(sub c)) on the degree of disorder as due to localization effects. Researchers discuss the possible reasons of fast T(sub c) degradation due to the enhanced Coulomb effects caused by the disorder induced decrease of localization length. The appearance and growth of localized magnetic moments is also discussed. The disorder dependence of localization length calculated from the experimental data on conductivity correlates reasonably with the theoretical criterion for suppression of superconductivity in the system with localized electronic states.
Localization at the edge of a 2D topological insulator by Kondo impurities with random anisotropies.
Altshuler, B L; Aleiner, I L; Yudson, V I
2013-08-23
We consider chiral electrons moving along the one-dimensional helical edge of a two-dimensional topological insulator and interacting with a disordered chain of Kondo impurities. Assuming the electron-spin couplings of random anisotropies, we map this system to the problem of the pinning of the charge density wave by the disordered potential. This mapping proves that arbitrary weak anisotropic disorder in coupling of chiral electrons with spin impurities leads to the Anderson localization of the edge states. PMID:24010457
GW approach to Anderson model in and out of equilibrium : scaling properties in the Kondo regime.
Spataru, Dan Catalin
2010-03-01
The low-energy properties of the Anderson model for a single impurity coupled to two leads are studied using the GW approximation. We find that quantities such as the spectral function at zero temperature, the linear-response conductance as function of temperature or the differential conductance as function of bias voltage exhibit universal scaling behavior in the Kondo regime. We show how the form of the GW scaling functions relates to the form of the scaling functions obtained from the exact solution at equilibrium. We also compare the energy scale that goes inside the GW scaling functions with the exact Kondo temperature, for a broad range of the Coulomb interaction strength in the asymptotic regime. This analysis allows to clarify a presently suspended question in the literature, namely whether or not the GW solution captures the Kondo resonance.
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.
Crossover from conventional to inverse indirect magnetic exchange in the depleted Anderson lattice
NASA Astrophysics Data System (ADS)
Aulbach, Maximilian W.; Titvinidze, Irakli; Potthoff, Michael
2015-05-01
We investigate the finite-temperature properties of an Anderson lattice with regularly depleted impurities. The physics of this model is ruled by two different magnetic exchange mechanisms: conventional Ruderman-Kittel-Kasuya-Yosida (RKKY) interaction at weak hybridization strength V and an inverse indirect magnetic exchange (IIME) at strong V , both favoring a ferromagnetic ground state. The stability of ferromagnetic order against thermal fluctuations is systematically studied by static mean-field theory for an effective low-energy spin-only model emerging perturbatively in the strong-coupling limit as well as by dynamical mean-field theory for the full model. The Curie temperature is found at a maximum for a half-filled conduction band and at intermediate hybridization strengths in the crossover regime between RKKY and IIME.
Non-Gaussian Spatial Correlations Dramatically Weaken Localization
NASA Astrophysics Data System (ADS)
Javan Mard, H.; Andrade, E. C.; Miranda, E.; Dobrosavljevi?, V.
2015-02-01
We perform variational studies of the interaction-localization problem to describe the interaction-induced renormalizations of the effective (screened) random potential seen by quasiparticles. Here we present results of careful finite-size scaling studies for the conductance of disordered Hubbard chains at half-filling and zero temperature. While our results indicate that quasiparticle wave functions remain exponentially localized even in the presence of moderate to strong repulsive interactions, we show that interactions produce a strong decrease of the characteristic conductance scale g* signaling the crossover to strong localization. This effect, which cannot be captured by a simple renormalization of the disorder strength, instead reflects a peculiar non-Gaussian form of the spatial correlations of the screened disordered potential, a hitherto neglected mechanism to dramatically reduce the impact of Anderson localization (interference) effects.
Suppression and Revival of Weak Localization through Control of Time-Reversal Symmetry
NASA Astrophysics Data System (ADS)
Müller, K.; Richard, J.; Volchkov, V. V.; Denechaud, V.; Bouyer, P.; Aspect, A.; Josse, V.
2015-05-01
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.
TDCS increases cortical excitability: direct evidence from TMS-EEG.
Romero Lauro, Leonor J; Rosanova, Mario; Mattavelli, Giulia; Convento, Silvia; Pisoni, Alberto; Opitz, Alexander; Bolognini, Nadia; Vallar, Giuseppe
2014-09-01
Despite transcranial direct current stimulation (tDCS) is increasingly used in experimental and clinical settings, its precise mechanisms of action remain largely unknown. At a neuronal level, tDCS modulates the resting membrane potential in a polarity-dependent fashion: anodal stimulation increases cortical excitability in the stimulated region, while cathodal decreases it. So far, the neurophysiological underpinnings of the immediate and delayed effects of tDCS, and to what extent the stimulation of a given cerebral region may affect the activity of anatomically connected regions, remain unclear. In the present study, we used a combination of Transcranial Magnetic Stimulation (TMS) and Electroencephalography (EEG) in order to explore local and global cortical excitability modulation during and after active and sham tDCS. Single pulse TMS was delivered over the left posterior parietal cortex (PPC), before, during, and after 15 min of tDCS over the right PPC, while EEG was recorded from 60 channels. For each session, indexes of global and local cerebral excitability were obtained, computed as global and local mean field power (Global Mean Field Power, GMFP and Local Mean Field Power, LMFP) on mean TMS-evoked potentials (TEPs) for three temporal windows: 0-50, 50-100, and 100-150 msec. The global index was computed on all 60 channels. The local indexes were computed in six clusters of electrodes: left and right in frontal, parietal and temporal regions. GMFP increased, compared to baseline, both during and after active tDCS in the 0-100 msec temporal window. LMFP increased after the end of stimulation in parietal and frontal clusters bilaterally, while no difference was found in the temporal clusters. In sum, a diffuse rise of cortical excitability occurred, both during and after active tDCS. This evidence highlights the spreading of the effects of anodal tDCS over remote cortical regions of stimulated and contralateral hemispheres. PMID:24998337
Resonant transfer excitation: Interference effects
Shafroth, S.M. [North Carolina Univ., Chapel Hill, NC (United States). Dept. of Physics and Astronomy; Benhenni, M. [North Carolina Univ., Chapel Hill, NC (United States). Dept. of Physics and Astronomy]|[Toulouse-3 Univ., 31 (France). Lab. de Decharges dans les Gaz; Swenson, J.K. [Oak Ridge National Lab., TN (United States)]|[Lawrence Livermore National Lab., CA (United States); Schulz, M. [Oak Ridge National Lab., TN (United States)]|[Missouri Univ., Rolla, MO (United States). Dept. of Physics; Giese, J.P.; Schone, H. [Oak Ridge National Lab., TN (United States)]|[Kansas State Univ., Manhattan, KS (United States). Dept. of Physics; Vane, C.R.; Dittner, P.F.; Datz, S. [Oak Ridge National Lab., TN (United States)
1991-12-31
Interference effects in RTE (Resonant Transfer Excitation) can be studied for low Z projectiles via Auger electrons emitted from highly ionized fast moving projectile ions following collisions with low Z targets. RTE in ion-atom collisions is closely related to dielectronic recombination. In the latter case which is of practical interest to the fusion power program an electron with the proper velocity incident on a highly charged ion is resonantly captured and simultaneously interacts with an inner shell electron to excite it, thus forming a doubly excited state which may decay predominantly by X-ray emission for higher Z ions or by Auger electron decay for lower Z ions. The resonant velocity is that of the Auger electron emitted by the ion in the doubly excited state in RTE the electrons to be captured are in low Z atomic (typically He) or Molecular (typically H{sub 2}) targets and the ions are produced by accelerators in highly charged states with the appropriate resonant velocity. The resonance is much broadened by the velocity distribution of the target electrons. Thus the resonance width as a function of projectile energy is determined by folding the Compton profile of the target electrons with the dielectronic recombination cross sections. A weaker effect and more speculative is Two Electron Transfer Excitation. Here one target electron excites the projectile 1s electron to the 2p shell for example and the other target electron is captured to an excited state of the projectile. This effect becomes more important at projectile energies higher than the energy where the RTE cross section has its maximum value. The electron--electron interaction has been beautifully demonstrated by Zouros et al. Finally, there might be interference with shakeup. This paper will present angular distribution measurements of Auger lines so that the effects of interference between these various processes can be studied.
Resonant transfer excitation: Interference effects
Shafroth, S.M. (North Carolina Univ., Chapel Hill, NC (United States). Dept. of Physics and Astronomy); Benhenni, M. (North Carolina Univ., Chapel Hill, NC (United States). Dept. of Physics and Astronomy Toulouse-3 Univ., 31 (France). Lab. de Decharges dans les Gaz); Swenson, J.K. (Oak Ridge National Lab., TN (United States) Lawrence Livermore National Lab., CA (United States)); Schulz, M. (Oak R
1991-01-01
Interference effects in RTE (Resonant Transfer Excitation) can be studied for low Z projectiles via Auger electrons emitted from highly ionized fast moving projectile ions following collisions with low Z targets. RTE in ion-atom collisions is closely related to dielectronic recombination. In the latter case which is of practical interest to the fusion power program an electron with the proper velocity incident on a highly charged ion is resonantly captured and simultaneously interacts with an inner shell electron to excite it, thus forming a doubly excited state which may decay predominantly by X-ray emission for higher Z ions or by Auger electron decay for lower Z ions. The resonant velocity is that of the Auger electron emitted by the ion in the doubly excited state in RTE the electrons to be captured are in low Z atomic (typically He) or Molecular (typically H{sub 2}) targets and the ions are produced by accelerators in highly charged states with the appropriate resonant velocity. The resonance is much broadened by the velocity distribution of the target electrons. Thus the resonance width as a function of projectile energy is determined by folding the Compton profile of the target electrons with the dielectronic recombination cross sections. A weaker effect and more speculative is Two Electron Transfer Excitation. Here one target electron excites the projectile 1s electron to the 2p shell for example and the other target electron is captured to an excited state of the projectile. This effect becomes more important at projectile energies higher than the energy where the RTE cross section has its maximum value. The electron--electron interaction has been beautifully demonstrated by Zouros et al. Finally, there might be interference with shakeup. This paper will present angular distribution measurements of Auger lines so that the effects of interference between these various processes can be studied.
Performance seeking control excitation mode
NASA Technical Reports Server (NTRS)
Schkolnik, Gerard
1995-01-01
Flight testing of the performance seeking control (PSC) excitation mode was successfully completed at NASA Dryden on the F-15 highly integrated digital electronic control (HIDEC) aircraft. Although the excitation mode was not one of the original objectives of the PSC program, it was rapidly prototyped and implemented into the architecture of the PSC algorithm, allowing valuable and timely research data to be gathered. The primary flight test objective was to investigate the feasibility of a future measurement-based performance optimization algorithm. This future algorithm, called AdAPT, which stands for adaptive aircraft performance technology, generates and applies excitation inputs to selected control effectors. Fourier transformations are used to convert measured response and control effector data into frequency domain models which are mapped into state space models using multiterm frequency matching. Formal optimization principles are applied to produce an integrated, performance optimal effector suite. The key technical challenge of the measurement-based approach is the identification of the gradient of the performance index to the selected control effector. This concern was addressed by the excitation mode flight test. The AdAPT feasibility study utilized the PSC excitation mode to apply separate sinusoidal excitation trims to the controls - one aircraft, inlet first ramp (cowl), and one engine, throat area. Aircraft control and response data were recorded using on-board instrumentation and analyzed post-flight. Sensor noise characteristics, axial acceleration performance gradients, and repeatability were determined. Results were compared to pilot comments to assess the ride quality. Flight test results indicate that performance gradients were identified at all flight conditions, sensor noise levels were acceptable at the frequencies of interest, and excitations were generally not sensed by the pilot.
Crystal-field excitations in UPdSn
NASA Astrophysics Data System (ADS)
Nakotte, H.; Robinson, R. A.; Bull, M.; McEwen, K.; Ecclestone, R.; Bruck, E.
1996-03-01
We have measured the inelastic neutron-scattering response of UPdSn at various temperatures using the spectrometers HET and PHAROS at ISIS and= LANSCE, respectively. Above 100 K, we find a clear excitation around 40= meV in addition to the phonon contribution. We believe that this excitation should be attributed to crystal fields and its observation in uranium intermetallics is very unusual. Furthermore, we find a strong shift in energy of this excitation to about 50 meV when entering the low-temperature magnetic phase, which we believe may be attributed to magnetically-driven structural distortions and a subsequent change in the local surrounding of the U ions.
Excitation of multipole plasmons by optical vortex beams.
Sakai, Kyosuke; Nomura, Kensuke; Yamamoto, Takeaki; Sasaki, Keiji
2015-01-01
Localized surface plasmon resonance (LSPR) has been shown to exhibit a strong potential for nanoscale electromagnetic field manipulation beyond the diffraction limit. Particularly dark mode plasmons circumvent radiation loss and store the energy long in time, which raise the prospect of interesting plasmonics applications, for example biochemical sensing and nanoscale lasing. Here we theoretically investigate a method of exciting multipole plasmons, including dark modes, using normally incident light. By performing numerical calculations, we show that multipole plasmons in metal nanodisks can be selectively excited by circularly-polarized optical vortex beams. We study the electromagnetic fields of the beam cross-sections and their correspondence with the excited multipole plasmon modes with respect to spin and orbital angular momenta. The transfer of angular momentum between photons and plasmons is also discussed. PMID:25672226
Bogoliubov excitations of disordered Bose-Einstein condensates
Gaul, Christopher [Departamento de Fisica de Materiales, Universidad Complutense, E-28040 Madrid (Spain); Mueller, Cord A. [Centre for Quantum Technologies, National University of Singapore, Singapore 117543 (Singapore)
2011-06-15
We describe repulsively interacting Bose-Einstein condensates in spatially correlated disorder potentials of arbitrary dimension. The first effect of disorder is to deform the mean-field condensate. The second is that the quantum excitation spectrum and condensate population are affected. By a saddle-point expansion of the many-body Hamiltonian around the deformed mean-field ground state, we derive the fundamental quadratic Hamiltonian of quantum fluctuations. Importantly, a basis is used such that excitations are orthogonal to the deformed condensate. Via Bogoliubov-Nambu perturbation theory, we compute the effective excitation dispersion, including mean free paths and localization lengths. Corrections to the speed of sound and average density of states are calculated, due to correlated disorder in arbitrary dimensions, extending to the case of weak lattice potentials.
Excitation of Multipole Plasmons by Optical Vortex Beams
Sakai, Kyosuke; Nomura, Kensuke; Yamamoto, Takeaki; Sasaki, Keiji
2015-01-01
Localized surface plasmon resonance (LSPR) has been shown to exhibit a strong potential for nanoscale electromagnetic field manipulation beyond the diffraction limit. Particularly dark mode plasmons circumvent radiation loss and store the energy long in time, which raise the prospect of interesting plasmonics applications, for example biochemical sensing and nanoscale lasing. Here we theoretically investigate a method of exciting multipole plasmons, including dark modes, using normally incident light. By performing numerical calculations, we show that multipole plasmons in metal nanodisks can be selectively excited by circularly-polarized optical vortex beams. We study the electromagnetic fields of the beam cross-sections and their correspondence with the excited multipole plasmon modes with respect to spin and orbital angular momenta. The transfer of angular momentum between photons and plasmons is also discussed. PMID:25672226
No Maxwell Electromagnetic Wave Field Excited In Cloaked Concealment
Xie, Ganquan; Xie, Feng; Xie, Lee
2009-01-01
The GL electromagnetic (EM) modeling is used to simulate the 3D EM full wave field propagation through cloaks. The 3D GL simulation of the EM wave field excited by a point source outside of the cloaks has been done. The simulation of the EM wave field from the point source excitation inside of the cloak device is presented in this paper. By using the GL modeling simulation, we found a phenomenon that there is no Maxwell EM wave field which is excited by nonzero local sources inside of the single layer cloaked concealment. The theoretical proof of the phenomenon by GL method is proposed in this paper. The GL method is fully different from the conventional methods. The GL method has double abilities of the theoretical analysis and numerical simulations to research the physical process and cloak metamaterial properties that is exhibited in this paper.
NASA Astrophysics Data System (ADS)
Shimizu, Yukihiro; Hewson, Alex; Sakai, Osamu
1999-09-01
The specific heat and the magnetisation of an impurity Anderson model,which has a non-Kramers doublet lowest state of an f 2 configurationsubject to the tetragonal crystalline electric field,are investigated using the numerical renormalization group method.We examine two cases where the ground states of the system arenon-Fermi-liquid (NFL) of two-channel Kondo type modeland local-Fermi-liquid (LFL), respectively.In the former case the temperature dependence of the specific heatshows a broad peak which has an entropy,0.5ln 2, in the absence of the magnetic field.The specific heat shows two peaks in a very weak magnetic field:one has the same temperature dependence as in the absence of the magneticfield, the other at very low temperatures shows a release of the residualentropy, 0.5 ln 2.In the LFL case the specific heat shows only one peak which hasan entropy, ln 2, in the absence of the magnetic field.The temperature dependence does not change in a very weak magnetic field.The ?-coefficient of the specific heat and the magneticsusceptibility never show - ln T dependence in the LFL case, even whenthe parameters are very close to the critical situation betweenNFL and LFL ground state.
Arjomandy, Bijan; Sahoo, Narayan; Zhu, X Ronald; Zullo, John R; Wu, Richard Y; Zhu, Mingping; Ding, Xiaoning; Martin, Craig; Ciangaru, George; Gillin, Michael T
2009-06-01
The number of proton and carbon ion therapy centers is increasing; however, since the publication of the International Commission on Radiation Units and Measurements report, there has been no dedicated report dealing with proton therapy quality assurance. The purpose of this article is to describe the quality assurance procedures performed on the passively scattered proton therapy beams at The University of Texas M. D. Anderson Cancer Center Proton Therapy Center in Houston. The majorities of these procedures are either adopted from procedures outlined in the American Association of Physicists in Medical Task Group (TG) 40 report or are a modified version of the TG 40 procedures. In addition, new procedures, which were designed specifically to be applicable to the synchrotron at the author's center, have been implemented. The authors' procedures were developed and customized to ensure patient safety and accurate operation of synchrotron to within explicit limits. This article describes these procedures and can be used by others as a guideline for developing QA procedures based on particle accelerator specific parameters and local regulations pertinent to any new facility. PMID:19610316
Extracting Excitations from Model State Entanglement
NASA Astrophysics Data System (ADS)
Sterdyniak, A.; Regnault, N.; Bernevig, B. A.
2011-03-01
We extend the concept of an entanglement spectrum from the geometrical to the particle bipartite partition. We apply this to several fractional quantum Hall wave functions on both sphere and torus geometries to show that this new type of entanglement spectra completely reveals the physics of bulk quasihole excitations. While this is easily understood when a local Hamiltonian for the model state exists, we show that the quasihole wave functions are encoded within the model state even when such a Hamiltonian is not known. As a nontrivial example, we look at Jain’s composite fermion states and obtain their quasiholes directly from the model state wave function. We reach similar conclusions for wave functions described by Jack polynomials.
Photoacoustic excitation profiles of gold nanoparticles?
Feis, Alessandro; Gellini, Cristina; Salvi, Pier Remigio; Becucci, Maurizio
2014-01-01
The wavelength dependence of the laser-induced photoacoustic signal amplitude has been measured for water dispersions of 10, 61, and 93 nm diameter gold nanospheres. The whole region of the localized surface plasmon resonance has been covered. This “photoacoustic excitation profile” can be overlayed with the extinction spectrum between 450 nm and 600 nm in the case of the smallest nanoparticles. At variance, the larger-sized nanoparticles display a progressive deviation from the extinction spectrum at longer wavelength, where the photoacoustic signal becomes relatively smaller. Considering that photoacoustics is intrinsically insensitive to light scattering, at least for optically thin samples, the results are in agreement with previous theoretical work predicting (i) an increasing contribution of scattering to extinction when the nanoparticle size increases and (ii) a larger scattering component at longer wavelengths. Therefore, the method has a general validity and can be applied to selectively determine light absorption by plasmonic systems. PMID:25302155
Multiscale photosynthetic and biomimetic excitation energy transfer
NASA Astrophysics Data System (ADS)
Ringsmuth, A. K.; Milburn, G. J.; Stace, T. M.
2012-07-01
Recent evidence suggests that quantum coherence enhances excitation energy transfer (EET) through individual photosynthetic light-harvesting protein complexes (LHCs). Its role in vivo is unclear however, where transfer to chemical reaction centres (RCs) spans larger, multi-LHC/RC networks. Here we predict maximum coherence lengths possible in fully connected chromophore networks with the generic structural and energetic features of multi-LHC/RC networks. A renormalization analysis reveals the dependence of EET dynamics on multiscale, hierarchical network structure. Surprisingly, thermal decoherence rate declines at larger length scales for physiological parameters and coherence length is instead limited by localization due to static disorder. Physiological parameters support coherence lengths up to ~ 5nm, which is consistent with observations of solvated LHCs and invites experimental tests for intercomplex coherences in multi-LHC/RC networks. Results further suggest that a semiconductor quantum dot network engineered with hierarchically clustered structure and small static disorder may support coherent EET over larger length scales, at ambient temperatures.
Adjustable, Broadband, Selective Excitation with Uniform Phase
Kristin E. Cano; Mari A. Smith; A. J. Shaka
2002-01-01
An advance in the problem of achieving broadband, selective, and uniform-phase excitation in NMR spectroscopy of liquids is outlined. Broadband means that, neglecting relaxation, any frequency bandwidth may be excited even when the available radiofrequency (RF) field strength is strictly limited. Selective means that sharp transition edges can be created between pure-phase excitation and no excitation at all. Uniform phase
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.
Adult neurogenesis modifies excitability of the dentate gyrus
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
NASA Astrophysics Data System (ADS)
Ramos, Edwin; Franco, Roberto; Silva-Valencia, Jereson; Figueira, Marcos Sergio
2014-12-01
We study the thermopower S, linear thermal conductance ?, linear electric conductance G and thermoelectric figure of merit Z properties of a single-walled zig-zag carbon nanotube side coupled to a correlated quantum dot (QD). We employ the recently developed U-finite atomic approach for the Single Impurity Anderson model (SIAM). The quantum dot is linked to the localized states in the model, considering a finite Coulombic repulsion U, and the conduction band in the model is associated with the single walled zig-zag metallic carbon nanotube (n=3), and is described by a tight-binding approximation in order to obtain Green's function of the nanotube. The thermoelectric transport coefficients were obtained using the Keldysh non-equilibrium Green's function technique with the Onsager relation in the linear regime automatically satisfied. Results indicate that this system can be employed in possible thermoelectric device applications at low temperatures when strong charge fluctuations are present in the QD.
Modeling excitable systems: Reentrant tachycardia
NASA Astrophysics Data System (ADS)
Lancaster, Jarrett L.; Hellen, Edward H.; Leise, Esther M.
2010-01-01
Excitable membranes are an important type of nonlinear dynamical system, and their study can be used to provide a connection between physical and biological circuits. We discuss two models of excitable membranes important in cardiac and neural tissues. One model is based on the Fitzhugh-Nagumo equations, and the other is based on a three-transistor excitable circuit. We construct a circuit that simulates reentrant tachycardia and its treatment by surgical ablation. This project is appropriate for advanced undergraduates as a laboratory capstone project or as a senior thesis or honors project and can also be a collaborative project, with one student responsible for the computational predictions and another for the circuit construction and measurements.
Autoresonant excitation of antiproton plasmas.
Andresen, G B; Ashkezari, M D; Baquero-Ruiz, M; Bertsche, W; Bowe, P D; Butler, E; Carpenter, P T; Cesar, C L; Chapman, S; Charlton, M; Fajans, J; Friesen, T; Fujiwara, M C; Gill, D R; Hangst, J S; Hardy, W N; Hayden, M E; Humphries, A J; Hurt, J L; Hydomako, R; Jonsell, S; Madsen, N; Menary, S; Nolan, P; Olchanski, K; Olin, A; Povilus, A; Pusa, P; Robicheaux, F; Sarid, E; Silveira, D M; So, C; Storey, J W; Thompson, R I; van der Werf, D P; Wurtele, J S; Yamazaki, Y
2011-01-14
We demonstrate controllable excitation of the center-of-mass longitudinal motion of a thermal antiproton plasma using a swept-frequency autoresonant drive. When the plasma is cold, dense, and highly collective in nature, we observe that the entire system behaves as a single-particle nonlinear oscillator, as predicted by a recent theory. In contrast, only a fraction of the antiprotons in a warm plasma can be similarly excited. Antihydrogen was produced and trapped by using this technique to drive antiprotons into a positron plasma, thereby initiating atomic recombination. PMID:21405235
Dynamics of Elastic Excitable Media
Julyan H. E. Cartwright; Victor M. Eguiluz; Emilio Hernandez-Garcia; Oreste Piro
1999-05-20
The Burridge-Knopoff model of earthquake faults with viscous friction is equivalent to a van der Pol-FitzHugh-Nagumo model for excitable media with elastic coupling. The lubricated creep-slip friction law we use in the Burridge-Knopoff model describes the frictional sliding dynamics of a range of real materials. Low-dimensional structures including synchronized oscillations and propagating fronts are dominant, in agreement with the results of laboratory friction experiments. Here we explore the dynamics of fronts in elastic excitable media.
Matlock, Stanley Wayne
1976-01-01
EVALUATION OF THE MODIFIED ANDERSON SAMPLER FOR DETERMINING PARTICLE SIZE DISTRIBUTIONS AND RESPIRABLE CONCENTRATIONS OF PARTICULATE MATTER PRESENT IN THE WORKING ENVIRONMENT OF COTTONSEED OIL MILLS A Thesis by STANLEY WAYNE MATLOCK Submitted... to the Graduate College of Texas A&M University in partial fulfillment of the requirement for the degree of MASTER OF SCIENCE August 1976 Major Subject: Agricultural Engineering FVALUATION OF THE MODIFIED ANDERSON SAMPLER FOR DETERMINING PARTICLE SIZE...
Daniel T. Lackland; David L. Bachman; Timothy D. Carter; Derek L. Barker; Stephen Timms; Harvinder Kohli
Background and Purpose—South Carolina and the southeastern United States have maintained the highest stroke mortality in the country. The Anderson and Pee Dee Stroke Study is an assessment of cerebrovascular disease incidence in 2 geographically defined communities in the stroke belt. Methods—Strokes were identified in the Anderson and Pee Dee areas of South Carolina. All hospitalized and out-of-hospital deaths occurring
David F. Moore; Markus Ries; Evelyn L. Forget; Raphael Schiffmann
2007-01-01
Background: Fabry-Anderson disease is an x-linked deficiency of lysosomal alpha-galactosidase A (GALA), resulting in chronic renal failure, cardiac arrhythmia, hypertrophy, valvular disease, pain (acro-paraesthesiae) and stroke, together with premature mortality. The disease has a significant impact on quality of life (QOL), as illustrated by studies using the EQ-5D. A specific treatment is available for Fabry-Anderson disease consisting of intravenous enzyme
Widespread Inhibition Proportional to Excitation Controls the Gain of a Leech Behavioral Circuit
Sandini, Giulio
Neuron Article Widespread Inhibition Proportional to Excitation Controls the Gain of a Leech network underlying local bending be- havior in leeches depends on widespread inhibition. Using behavioral the amplitude of a simple reflexive response--local bending--in the medicinal leech, a response that is elicited
Relaxation of Excited States in Nonlinear Schrödinger Equations
Tai-Peng Tsai; Horng-Tzer Yau
2001-10-08
We consider a nonlinear Schr\\"odinger equation in $\\R^3$ with a bounded local potential. The linear Hamiltonian is assumed to have two bound states with the eigenvalues satisfying some resonance condition. Suppose that the initial data is small and is near some nonlinear {\\it excited} state. We give a sufficient condition on the initial data so that the solution to the nonlinear Schr\\"odinger equation approaches to certain nonlinear {\\it ground} state as the time tends to infinity.