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1

Anderson localized optical fibers  

NASA Astrophysics Data System (ADS)

Anderson localization has been a subject of fascination and intense research for more than fifty years. It is highly desirable to harness its curious and interesting properties in practical applications. We have taken a step in this direction by using this phenomenon as the wave guiding mechanism in optical fibers. We have shown, both experimentally and numerically, that for a moderate amount of disorder in optical fibers, transverse localization results in an effective propagating beam diameter that is comparable to that of a typical index-guiding optical fiber.1, 2 In this work, we investigate the effect of macro-bending on the localization properties in a disordered polymer optical fiber both experimentally and numerically. We show that macro-bending in ranges of practical interest does not significantly affect the beam propagation in Anderson localized fibers as long as the strong localization dominates the effect of bending.

Karbasi, Salman; Koch, Karl W.; Mafi, Arash

2013-02-01

2

Anderson Localization of Solitons  

SciTech Connect

At low temperature, a quasi-one-dimensional ensemble of atoms with an attractive interaction forms a bright soliton. When exposed to a weak and smooth external potential, the shape of the soliton is hardly modified, but its center-of-mass motion is affected. We show that in a spatially correlated disordered potential, the quantum motion of a bright soliton displays Anderson localization. The localization length can be much larger than the soliton size and could be observed experimentally.

Sacha, Krzysztof; Zakrzewski, Jakub [Instytut Fizyki imienia Mariana Smoluchowskiego and Mark Kac Complex Systems Research Center, Uniwersytet Jagiellonski, ulica Reymonta 4, PL-30-059 Krakow (Poland); Laboratoire Kastler-Brossel, UPMC, ENS, CNRS, 4 Place Jussieu, F-75005 Paris (France); Mueller, Cord A. [Laboratoire Kastler-Brossel, UPMC, ENS, CNRS, 4 Place Jussieu, F-75005 Paris (France); Physikalisches Institut, Universitaet Bayreuth, D-95440 Bayreuth (Germany); Delande, Dominique [Laboratoire Kastler-Brossel, UPMC, ENS, CNRS, 4 Place Jussieu, F-75005 Paris (France)

2009-11-20

3

Anderson localization of solitons.  

PubMed

At low temperature, a quasi-one-dimensional ensemble of atoms with an attractive interaction forms a bright soliton. When exposed to a weak and smooth external potential, the shape of the soliton is hardly modified, but its center-of-mass motion is affected. We show that in a spatially correlated disordered potential, the quantum motion of a bright soliton displays Anderson localization. The localization length can be much larger than the soliton size and could be observed experimentally. PMID:20366020

Sacha, Krzysztof; Müller, Cord A; Delande, Dominique; Zakrzewski, Jakub

2009-11-17

4

Anderson localization in laser-kicked molecules  

NASA Astrophysics Data System (ADS)

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

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

2013-08-01

5

Localization by bichromatic potentials versus Anderson localization  

SciTech Connect

The one-dimensional propagation of waves in a bichromatic potential may be modeled by the Aubry-Andre Hamiltonian. This, in turn, presents a localization transition that has been observed in recent experiments using ultracold atoms or light. It is shown here that, in contrast to the Anderson model, the localization mechanism has a classical origin, namely it is not due to a quantum suppression of a classically allowed transport process, but rather is produced by a trapping by the potential. Explicit comparisons with the Anderson model as well as with experiments are presented.

Albert, Mathias; Leboeuf, Patricio [Laboratoire de Physique Theorique et Modeles Statistiques, CNRS, Universite Paris Sud, UMR8626, F-91405 Orsay Cedex (France)

2010-01-15

6

Anderson localization makes adiabatic quantum optimization fail.  

PubMed

Understanding NP-complete problems is a central topic in computer science (NP stands for nondeterministic polynomial time). This is why adiabatic quantum optimization has attracted so much attention, as it provided a new approach to tackle NP-complete problems using a quantum computer. The efficiency of this approach is limited by small spectral gaps between the ground and excited states of the quantum computer's Hamiltonian. We show that the statistics of the gaps can be analyzed in a novel way, borrowed from the study of quantum disordered systems in statistical mechanics. It turns out that due to a phenomenon similar to Anderson localization, exponentially small gaps appear close to the end of the adiabatic algorithm for large random instances of NP-complete problems. This implies that unfortunately, adiabatic quantum optimization fails: The system gets trapped in one of the numerous local minima. PMID:20616043

Altshuler, Boris; Krovi, Hari; Roland, Jérémie

2010-06-24

7

Anderson localization makes adiabatic quantum optimization fail  

PubMed Central

Understanding NP-complete problems is a central topic in computer science (NP stands for nondeterministic polynomial time). This is why adiabatic quantum optimization has attracted so much attention, as it provided a new approach to tackle NP-complete problems using a quantum computer. The efficiency of this approach is limited by small spectral gaps between the ground and excited states of the quantum computer’s Hamiltonian. We show that the statistics of the gaps can be analyzed in a novel way, borrowed from the study of quantum disordered systems in statistical mechanics. It turns out that due to a phenomenon similar to Anderson localization, exponentially small gaps appear close to the end of the adiabatic algorithm for large random instances of NP-complete problems. This implies that unfortunately, adiabatic quantum optimization fails: The system gets trapped in one of the numerous local minima.

Altshuler, Boris; Krovi, Hari; Roland, Jeremie

2010-01-01

8

Universal mechanism for Anderson and weak localization  

PubMed Central

Localization of stationary waves occurs in a large variety of vibrating systems, whether mechanical, acoustical, optical, or quantum. It is induced by the presence of an inhomogeneous medium, a complex geometry, or a quenched disorder. One of its most striking and famous manifestations is Anderson localization, responsible for instance for the metal-insulator transition in disordered alloys. Yet, despite an enormous body of related literature, a clear and unified picture of localization is still to be found, as well as the exact relationship between its many manifestations. In this paper, we demonstrate that both Anderson and weak localizations originate from the same universal mechanism, acting on any type of vibration, in any dimension, and for any domain shape. This mechanism partitions the system into weakly coupled subregions. The boundaries of these subregions correspond to the valleys of a hidden landscape that emerges from the interplay between the wave operator and the system geometry. The height of the landscape along its valleys determines the strength of the coupling between the subregions. The landscape and its impact on localization can be determined rigorously by solving one special boundary problem. This theory allows one to predict the localization properties, the confining regions, and to estimate the energy of the vibrational eigenmodes through the properties of one geometrical object. In particular, Anderson localization can be understood as a special case of weak localization in a very rough landscape.

Filoche, Marcel; Mayboroda, Svitlana

2012-01-01

9

Anderson localization problems in gapless superconducting phases  

NASA Astrophysics Data System (ADS)

The interplay of Anderson localization and different kinds of superconducting order is most interesting in ``gapless'' cases, i.e. for nonvanishing electron density of states at EF. I present a new renormalization group result for Anderson localization in the gapless type II limit of an Ising superconducting (SC) glass. From this calculation a guess is also made for the XY superconducting glass. In both cases, and in contrast to localization in normal systems, two renormalization constants (one for field- and one for coupling constant renormalization) are necessary (and sufficient). The density of states at EF is singular with exponent ?. For the Ising SC-glass I obtain vI = 1/(d - 2), ?I = 1/2, and ?I = 0, while the XY SC-glass has vXY = 1/(d - 2), ?XY = 1, and ?XY = d - 2, all in leading order of the d - 2 expansion and for E = EF. For E?EF a symmetry argument, and also the calculation given here, predict usual localization behaviour with v = 1/(d - 2), ? = 0, and ? = 2 - d in both cases. The effects of Cooper pairs on localization in the pure superconducting glasses is compared with earlier results showing perfect coexistence of Anderson localization with dirty superconductivity approximately described by a nonrandom order parameter. These limiting cases are embedded in a more general field theory given here, which contains three superconducting order parameters and a conventional pair-breaking mechanism.

Oppenmann, R.

1990-08-01

10

Anderson localization of partially incoherent light  

SciTech Connect

We study Anderson localization and propagation of partially spatially incoherent wavepackets in linear disordered potentials, motivated by the insight that interference phenomena resulting from multiple scattering are affected by the coherence of the waves. We find that localization is delayed by incoherence: the more incoherent the waves are, the longer they diffusively spread while propagating in the medium. However, if all the eigenmodes of the system are exponentially localized (as in one- and two-dimensional disordered systems), any partially incoherent wavepacket eventually exhibits localization with exponentially decaying tails, after sufficiently long propagation distances. Interestingly, we find that the asymptotic behavior of the incoherent beam is similar to that of a single instantaneous coherent realization of the beam.

Capeta, D.; Radic, J.; Buljan, H. [Department of Physics, University of Zagreb, PP 332, 10000 Zagreb (Croatia); Szameit, A.; Segev, M. [Physics Department and Solid State Institute, Technion, Haifa 32000 (Israel)

2011-07-15

11

Anderson localization of polar eigenmodes in random planar composites  

NASA Astrophysics Data System (ADS)

Anderson localization of classical waves in disordered media is a fundamental physical phenomenon that has attracted attention in the past three decades. More recently, localization of polar excitations in nanostructured metal-dielectric films (also known as random planar composites) has been subject of intense studies. Potential applications of planar composites include local near-field microscopy and spectroscopy. A number of previous studies have relied on the quasistatic approximation and a direct analogy with localization of electrons in disordered solids. Here I consider the localization problem without the quasistatic approximation. I show that localization of polar excitations is characterized by algebraic rather than by exponential spatial confinement. This result is also valid in two and three dimensions. I also show that the previously used localization criterion based on the gyration radius of eigenmodes is inconsistent with both exponential and algebraic localization. An alternative criterion based on the dipole participation number is proposed. Numerical demonstration of a localization-delocalization transition is given. Finally, it is shown that, contrary to the previous belief, localized modes can be effectively coupled to running waves.

Markel, Vadim A.

2006-12-01

12

Microwave-Driven Atoms: From Anderson Localization to Einstein's Photoeffect  

SciTech Connect

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 photoeffect in the atomic ionization signal.

Schelle, Alexej [Physikalisches Institut der Albert-Ludwigs-Universitaet, Hermann-Herder-Strasse 3, D-79104 Freiburg (Germany); Laboratoire Kastler-Brossel, Universite Pierre et Marie Curie-Paris 6, ENS, CNRS, 4, Place Jussieu, F-75005 Paris (France); Delande, Dominique [Laboratoire Kastler-Brossel, Universite Pierre et Marie Curie-Paris 6, ENS, CNRS, 4, Place Jussieu, F-75005 Paris (France); Buchleitner, Andreas [Physikalisches Institut der Albert-Ludwigs-Universitaet, Hermann-Herder-Strasse 3, D-79104 Freiburg (Germany)

2009-05-08

13

Anderson localization of light near boundaries of disordered photonic lattices  

SciTech Connect

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

Jovic, Dragana M. [Institute of Physics, P. O. Box 57, 11001 Belgrade (Serbia); Texas A and M University at Qatar, P. O. Box 23874, Doha (Qatar); Kivshar, Yuri S. [Nonlinear Physics Center, Research School of Physics and Engineering, Australian National University, Canberra ACT 0200 (Australia); Denz, Cornelia [Institut fuer Angewandte Physik and Center for Nonlinear Science (CeNoS), Westfaelische Wilhelms-Universitaet Muenster, D-48149 Muenster (Germany); Belic, Milivoj R. [Texas A and M University at Qatar, P. O. Box 23874, Doha (Qatar)

2011-03-15

14

Dynamics of Anderson localization in open 3D media.  

PubMed

We develop a self-consistent theoretical approach to the dynamics of Anderson localization in open three-dimensional (3D) disordered media. The approach allows us to study time-dependent transmission and reflection, and the distribution of decay rates of quasimodes of 3D disordered slabs near the Anderson mobility edge. PMID:16486824

Skipetrov, S E; van Tiggelen, B A

2006-02-01

15

Anderson localization of one-dimensional hybrid particles  

NASA Astrophysics Data System (ADS)

We solve the Anderson localization problem on a two-leg ladder by the Fokker-Planck equation approach. The solution is exact in the weak disorder limit at a fixed interchain coupling. The study is motivated by progress in investigating the hybrid particles such as cavity polaritons. This application corresponds to parametrically different intrachain hopping integrals (a “fast” chain coupled to a “slow” chain). We show that the canonical Dorokhov-Mello-Pereyra-Kumar (DMPK) equation is insufficient for this problem. Indeed, the angular variables describing the eigenvectors of the transmission matrix enter into an extended DMPK equation in a nontrivial way, being entangled with the two transmission eigenvalues. This extended DMPK equation is solved analytically and the two Lyapunov exponents are obtained as functions of the parameters of the disordered ladder. The main result of the paper is that near the resonance energy, where the dispersion curves of the two decoupled and disorder-free chains intersect, the localization properties of the ladder are dominated by those of the slow chain. Away from the resonance they are dominated by the fast chain: a local excitation on the slow chain may travel a distance of the order of the localization length of the fast chain.

Xie, Hong-Yi; Kravtsov, V. E.; Müller, M.

2012-07-01

16

Mean-field description of Anderson localization transition  

NASA Astrophysics Data System (ADS)

The Anderson model of noninteracting disordered electrons is studied in high spatial dimensions. In this limit the coupled Bethe-Salpeter equations determining two-particle vertices (parquet equations) reduce to a single algebraic equation for a local vertex. We find a disorder-driven bifurcation point in this equation signaling vanishing of electron diffusion and onset of Anderson localization. There is no bifurcation in d=1,2 where all states are localized. In dimensions d>=3 the mobility edge separating metallic and insulating phase is found for various types of disorder and compared with results of other treatments.

Kolorenc, Jindrich; Janis, Vaclav

2006-03-01

17

Anderson localization for Bernoulli and other singular potentials  

Microsoft Academic Search

We prove exponential localization in the Anderson model under very weak assumptions on the potential distribution. In one dimension we allow any measure which is not concentrated on a single point and possesses some finite moment. In particular this solves the longstanding problem of localization for Bernoulli potentials (i.e., potentials that take only two values). In dimensions greater than one

Rene Carmona; Abel Klein; Fabio Martinelli

1987-01-01

18

Typical-Medium Theory of Mott-Anderson Localization  

NASA Astrophysics Data System (ADS)

The Mott and the Anderson routes to localization have long been recognized as the two basic processes that can drive the metal-insulator transition (MIT). Theories separately describing each of these mechanisms were discussed long ago, but an accepted approach that can include both has remained elusive. The lack of any obvious static symmetry distinguishing the metal from the insulator poses another fundamental problem, since an appropriate static order parameter cannot be easily found. More recent work, however, has revisited the original arguments of Anderson and Mott, which stressed that the key diference between the metal end the insulator lies in the dynamics of the electron. This physical picture has suggested that the "typical" (geometrically averaged) escape rate ? typ-1 = exp < ln ? esc-1> from a given lattice site should be regarded as the proper dynamical order parameter for the MIT, one that can naturally describe both the Anderson and the Mott mechanism for localization. This article provides an overview of the recent results obtained from the corresponding Typical-Medium Theory, which provided new insight into the the two-fluid character of the Mott-Anderson transition.

Dobrosavljevi?, V.

19

Rare Fluctuation Effects in the Anderson Model of Localization  

NASA Astrophysics Data System (ADS)

Two significant advances in the theory of disordered systems in the past three decades have been (i) the development of large disorder Renormalization Group methods, and (ii) a more concerted effort to study of the effects of rare fluctuations or configurations, such as Griffiths' phenomena. A major problem facing the latter in many-body systems has been the enormous numerical resources needed to see these rare phenomena. In this talk, we examine the issue of rare configuration effects in Anderson's original model of localization (1958). In this talk, we examine the issue of rare configuration effects in Anderson's original model of localization. We show that effects due to resonant tunneling among neighboring sites leads not only to anomalous behavior of electronic eigenstates far in the Lifshitz tail, where the density of states is exponentially suppressed, but also leads to singularities in average properties (i.e. the inverse participation ratio) as a function of energy, where the density of states is large. The singular behavior, which separates resonant, Lifshitz-like states from typical, Anderson-localized states, occurs in the insulating phase, and thus is present in all dimensions [1]. Using the analytic solution of a toy model, as well as numerical results of the Anderson model for several different disorder distributions in dimensions d = 1, 2 and 3, we show that this separation of eigenstates due to rare fluctuations is a ubiquitous property of the Anderson model with bounded disorder. This suggests that the half-century-old model, being solvable in polynomial time, is a prime candidate for detailed numerical studies of rare fluctuation effects in disordered systems. [4pt] [1] Sonika Johri and R. N. Bhatt, arXiv1106.1131; and in preparation.

Bhatt, Ravindra

2012-02-01

20

Three-Dimensional Anderson Localization in Variable Scale Disorder  

NASA Astrophysics Data System (ADS)

We report on the impact of variable-scale disorder on 3D Anderson localization of a noninteracting ultracold atomic gas. A spin-polarized gas of fermionic atoms is localized by allowing it to expand in an optical speckle potential. Using a sudden quench of the localized density distribution, we verify that the density profile is representative of the underlying single-particle localized states. The geometric mean of the disordering potential correlation lengths is varied by a factor of 4 via adjusting the aperture of the speckle focusing lens. We observe that the root-mean-square size of the localized gas increases approximately linearly with the speckle correlation length, in qualitative agreement with the scaling predicted by weak scattering theory.

McGehee, W. R.; Kondov, S. S.; Xu, W.; Zirbel, J. J.; DeMarco, B.

2013-10-01

21

Three-dimensional anderson localization in variable scale disorder.  

PubMed

We report on the impact of variable-scale disorder on 3D Anderson localization of a noninteracting ultracold atomic gas. A spin-polarized gas of fermionic atoms is localized by allowing it to expand in an optical speckle potential. Using a sudden quench of the localized density distribution, we verify that the density profile is representative of the underlying single-particle localized states. The geometric mean of the disordering potential correlation lengths is varied by a factor of 4 via adjusting the aperture of the speckle focusing lens. We observe that the root-mean-square size of the localized gas increases approximately linearly with the speckle correlation length, in qualitative agreement with the scaling predicted by weak scattering theory. PMID:24138250

McGehee, W R; Kondov, S S; Xu, W; Zirbel, J J; Demarco, B

2013-10-02

22

Strong coupling to two-dimensional anderson localized modes.  

PubMed

We use a scattering formalism to derive a condition of strong coupling between a resonant scatterer and an Anderson localized mode for electromagnetic waves in two dimensions. The strong coupling regime is demonstrated based on exact numerical simulations, in perfect agreement with theory. The strong coupling threshold can be expressed in terms of the Thouless conductance and the Purcell factor. This connects key concepts in transport theory and cavity quantum electrodynamics, and provides a practical tool for the design or analysis of experiments. PMID:23952400

Cazé, A; Pierrat, R; Carminati, R

2013-07-31

23

Non-conventional Anderson localization in bilayered structures  

NASA Astrophysics Data System (ADS)

We resolve the problem of non-conventional Anderson localization emerging in bilayered periodic-on-average structures with alternating layers of materials with positive and negative refraction indices. Recently, it was numerically discovered that in such structures with weak fluctuations of refractive indices, the localization length Lloc can be enormously large for small wave frequencies ?. Within a new approach allowing us to go beyond the second order of perturbation theory, we derive the expression for Lloc valid for any ? and small variance of disorder, ?2Lt1. In the limit ??0 one gets a quite specific dependence, L-1loc~?4?8. Our approach allows one to establish the conditions under which this effect occurs.

Torres-Herrera, E. J.; Izrailev, F. M.; Makarov, N. M.

2012-04-01

24

Anderson localization of a non-interacting Bose-Einstein condensate  

Microsoft Academic Search

Anderson localization of waves in disordered media was originally predicted fifty years ago, in the context of transport of electrons in crystals. The phenomenon is much more general and has been observed in a variety of systems, including light waves. However, Anderson localization has not been observed directly for matter waves. Owing to the high degree of control over most

Giacomo Roati; Chiara D'Errico; Leonardo Fallani; Marco Fattori; Chiara Fort; Matteo Zaccanti; Giovanni Modugno; Michele Modugno; Massimo Inguscio

2008-01-01

25

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

NASA Astrophysics Data System (ADS)

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

Floß, Johannes; Averbukh, Ilya Sh.

2012-08-01

26

Mean-field theory of Anderson localization: Asymptotic solution in high spatial dimensions  

NASA Astrophysics Data System (ADS)

The Anderson model of noninteracting disordered electrons is studied in high spatial dimensions. We find that off-diagonal one- and two-particle propagators behave as Gaussian random variables with respect to momentum summations. With this simplification and with the electron-hole symmetry we reduce the parquet equations for two-particle irreducible vertices to a single algebraic equation for a local vertex. We find a disorder-driven bifurcation point in this equation signaling vanishing of diffusion and onset of Anderson localization. There is no bifurcation in d=1,2 where all states are localized. A natural order parameter for Anderson localization emerges from the construction.

Janiš, V.; Koloren?, J.

2005-01-01

27

A local moment approach to the degenerate Anderson impurity model.  

PubMed

The local moment approach is extended to the orbitally degenerate (SU(2N)) Anderson impurity model (AIM). Single-particle dynamics are obtained over the full range of energy scales, focusing on particle-hole symmetry in the strongly-correlated regime where the onsite Coulomb interaction leads to many-body Kondo physics with entangled spin and orbital degrees of freedom. The approach captures many-body broadening of the Hubbard satellites and recovers the correct exponential vanishing of the Kondo scale for all N, and its universal scaling spectra are found to be in very good agreement with numerical renormalization group (NRG) results. In particular the high-frequency logarithmic decays of the scaling spectra, obtained here in closed form for arbitrary N, coincide essentially perfectly with available numerics from the NRG. A particular case of an anisotropic Coulomb interaction, in which the model represents a system of N 'capacitively coupled' SU(2) AIMs, is also discussed. Here the model is generally characterized by two low-energy scales, the crossover between which is seen directly in its dynamics. PMID:21832350

Galpin, Martin R; Gilbert, Anne B; Logan, David E

2009-08-13

28

A local moment approach to the degenerate Anderson impurity model  

NASA Astrophysics Data System (ADS)

The local moment approach is extended to the orbitally degenerate (SU(2N)) Anderson impurity model (AIM). Single-particle dynamics are obtained over the full range of energy scales, focusing on particle-hole symmetry in the strongly-correlated regime where the onsite Coulomb interaction leads to many-body Kondo physics with entangled spin and orbital degrees of freedom. The approach captures many-body broadening of the Hubbard satellites and recovers the correct exponential vanishing of the Kondo scale for all N, and its universal scaling spectra are found to be in very good agreement with numerical renormalization group (NRG) results. In particular the high-frequency logarithmic decays of the scaling spectra, obtained here in closed form for arbitrary N, coincide essentially perfectly with available numerics from the NRG. A particular case of an anisotropic Coulomb interaction, in which the model represents a system of N 'capacitively coupled' SU(2) AIMs, is also discussed. Here the model is generally characterized by two low-energy scales, the crossover between which is seen directly in its dynamics.

Galpin, Martin R.; Gilbert, Anne B.; Logan, David E.

2009-09-01

29

Routes Towards Anderson-Like Localization of Bose-Einstein Condensates in Disordered Optical Lattices  

SciTech Connect

We investigate, both experimentally and theoretically, possible routes towards Anderson-like localization of Bose-Einstein condensates in disordered potentials. The dependence of this quantum interference effect on the nonlinear interactions and the shape of the disorder potential is investigated. Experiments with an optical lattice and a superimposed disordered potential reveal the lack of Anderson localization. A theoretical analysis shows that this absence is due to the large length scale of the disorder potential as well as its screening by the nonlinear interactions. Further analysis shows that incommensurable superlattices should allow for the observation of the crossover from the nonlinear screening regime to the Anderson localized case within realistic experimental parameters.

Schulte, T.; Drenkelforth, S.; Kruse, J.; Ertmer, W.; Arlt, J. [Institut fuer Quantenoptik, Universitaet Hannover, Welfengarten 1, D-30167 Hannover (Germany); Sacha, K.; Zakrzewski, J. [Instytut Fizyki Mariana Smoluchowskiego, Uniwersytet Jagiellonski, PL-30-059 Cracow (Poland); Lewenstein, M. [Institut fuer Theoretische Physik, Universitaet Hannover, D-30167 Hannover (Germany); ICFO - Institut de Ciencies Fotoniques, 08034 Barcelona (Spain)

2005-10-21

30

Self-Consistent Theory of Anderson Localization:. General Formalism and Applications  

NASA Astrophysics Data System (ADS)

The self-consistent theory of Anderson localization of quantum particles or classical waves in disordered media is reviewed. After presenting the basic concepts of the theory of Anderson localization in the case of electrons in disordered solids, the regimes of weak and strong localization are discussed. Then the scaling theory of the Anderson localization transition is reviewed. The renormalization group theory is introduced and results and consequences are presented. It is shown how scale-dependent terms in the renormalized perturbation theory of the inverse diffusion coefficient lead in a natural way to a self-consistent equation for the diffusion coefficient. The latter accounts quantitatively for the static and dynamic transport properties except for a region near the critical point. Several recent applications and extensions of the self-consistent theory, in particular for classical waves, are discussed.

Wölfle, P.; Vollhardt, D.

31

Classical Coset Hamiltonian for the Electronic Motion and its Application to Anderson Localization and Hammett Equation  

Microsoft Academic Search

A classical coset Hamiltonian is introduced for the system of one electron in multi-sites. By this Hamiltonian, the dynamical behaviour of the electronic motion can be readily simulated. The simulation reproduces the retardation of the electron density decay in a lattice with site energies randomly distributed - an analogy with Anderson localization. This algorithm is also applied to reproduce the

Guan Xing; Guo-Zhen Wu

2001-01-01

32

The Effects of the Mean-Field Interaction on the Anderson Localization of Graphene Nanoribbons  

NASA Astrophysics Data System (ADS)

A generalized tight-binding (TB) model,footnotetextHancock et al. PRB 81, 245402 (2010). which includes a mean-field Hubbard-U and up to 3rd nearest-neighbor hopping terms, is applied to edge-disordered zigzag graphene nanoribbons in order to study spin-transport within the Landauer-B"utticker formalism. Edge-disorder is modeled by random perturbation of the on-site energy in the range -E..E on all edge atoms, and the resulting Anderson localization lengths determined. We compared the Anderson localization lengths and spin-transport features obtained from the generalized model, an extended TB model (non-interacting) and the simplified TB model (1st nearest neighbor hopping only). Within the range ±E=0.5 eV the Anderson localization length for a single spin was found to decrease by 86.4% with the introduction of the Hubbard-U in the generalized model compared to the non-interacting models, whereas the opposite spin remained unchanged across all model types. For the range ±E=2.0 eV the Anderson localization length for both spin types decreased by 71.4% and 76.2% in the generalized model when compared to the extended TB model, and 76.5% and 80.4% when compared to the simplified TB model.

Baldwin, Jack; Hancock, Y.

2013-03-01

33

The Weak Localization for the Alloy-Type Anderson Model on a Cubic Lattice  

NASA Astrophysics Data System (ADS)

We consider alloy type random Schrödinger operators on a cubic lattice whose randomness is generated by the sign-indefinite single-site potential. We derive Anderson localization for this class of models in the Lifshitz tails regime, i.e. when the coupling parameter ? is small, for the energies E?- C? 2.

Cao, Zhenwei; Elgart, Alexander

2012-09-01

34

Finite-size effects in Anderson localization of one-dimensional Bose-Einstein condensates  

SciTech Connect

We investigate the disorder-induced localization transition in Bose-Einstein condensates for the Anderson and Aubry-Andre models in the noninteracting limit using exact diagonalization. We show that, in addition to the standard superfluid fraction, other tools such as the entanglement and fidelity can provide clear signatures of the transition. Interestingly, the fidelity exhibits good sensitivity even for small lattices. Effects of the system size on these quantities are analyzed in detail, including the determination of a finite-size-scaling law for the critical disorder strength in the case of the Anderson model.

Cestari, J. C. C.; Foerster, A.; Gusmao, M. A. [Instituto de Fisica, Universidade Federal do Rio Grande do Sul, Porto Alegre, Rio Grande do Sul (Brazil)

2010-12-15

35

Anderson localization in optical lattices with speckle disorder  

SciTech Connect

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

Sucu, Serpil; Aktas, Saban; Okan, S. Erol [Department of Physics, Trakya University, 22030 Edirne (Turkey); Akdeniz, Zehra [Piri Reis University, 34940 Tuzla-Istanbul (Turkey); Vignolo, Patrizia [Universite de Nice-Sophia Antipolis, Institut non Lineaire de Nice, CNRS, 1361 route des Lucioles, F-06560 Valbonne (France)

2011-12-15

36

Tailoring Anderson localization by disorder correlations in 1D speckle potentials  

NASA Astrophysics Data System (ADS)

We study Anderson localization of single particles in continuous, correlated, one-dimensional disordered potentials. We show that tailored correlations can completely change the energy-dependence of the localization length. By considering two suitable models of disorder, we explicitly show that disorder correlations can lead to a nonmonotonic behavior of the localization length versus energy. Numerical calculations performed within the transfer-matrix approach and analytical calculations performed within the phase formalism up to order three show excellent agreement and demonstrate the effect. We finally show how the nonmonotonic behavior of the localization length with energy can be observed using expanding ultracold-atom gases.

Piraud, Marie; Sanchez-Palencia, Laurent

2013-02-01

37

Anderson localization of a Bose-Einstein condensate in a 3D random potential.  

PubMed

We study the effect of Anderson localization on the expansion of a Bose-Einstein condensate, released from a harmonic trap, in a 3D random potential. We use scaling arguments and the self-consistent theory of localization to show that the long-time behavior of the condensate density is controlled by a single parameter equal to the ratio of the mobility edge and the chemical potential of the condensate. We find that the two critical exponents of the localization transition determine the evolution of the condensate density in time and space. PMID:18518212

Skipetrov, S E; Minguzzi, A; van Tiggelen, B A; Shapiro, B

2008-04-24

38

Unified description of perturbation theory and band center anomaly in one-dimensional Anderson localization  

NASA Astrophysics Data System (ADS)

We calculated numerically the localization length of one-dimensional Anderson model with diagonal disorder. For weak disorder, we showed that the localization length changes continuously as the energy changes from the band center to the boundary of the anomalous region near the band edge. We found that all the localization lengths for different disorder strengths and different energies collapse onto a single curve, which can be fitted by a simple equation. Thus the description of the perturbation theory and the band center anomaly were unified into this equation.

Kang, Kai; Qin, Shaojing; Wang, Chuilin

2011-09-01

39

Anderson localization of 3d Mn states in semi-Heusler phases  

NASA Astrophysics Data System (ADS)

The solid solutions NiTi1-xMnxSb and CoV1-xMnxSb between metallic compounds are studied. For low Mn concentrations, Mn 3d states are localized as shown by magnetic measurements and electronic structure calculations. Magnetic interactions suddenly and strongly increase near x=0.4, while a semiconductinglike behavior is observed in the range x=0.35-0.45. These features are tentatively explained by the Anderson localization of d states in these disordered solutions. Large magnetoresistance effects are observed in some phases near their magnetic ordering temperature.

Kaczmarska, K.; Pierre, J.; Tobola, J.; Skolozdra, R. V.

1999-07-01

40

Mean-field theories for disordered electrons: Diffusion pole and Anderson localization  

NASA Astrophysics Data System (ADS)

We discuss conditions to be put on mean-field-like theories to be able to describe fundamental physical phenomena in disordered electron systems. In particular, we investigate options for a consistent mean-field theory of electron localization and for a reliable description of transport properties. We argue that a mean-field theory for the Anderson localization transition must be electron-hole symmetric and self-consistent at the two-particle (vertex) level. We show that such a theory with local equations can be derived from the asymptotic limit to high spatial dimensions. The weight of the diffusion pole, i.e., the number of diffusive states at the Fermi energy, in this mean-field theory decreases with the increasing disorder strength and vanishes in the localized phase. Consequences of the disclosed behavior for our understanding of vanishing of electron diffusion are discussed.

Janiš, V.; Koloren?, J.

2005-06-01

41

Anderson localization with second quantized fields in a coupled array of waveguides  

SciTech Connect

We report a theoretical study of Anderson localization of nonclassical light in an array of waveguides in which neighboring waveguides are evanescently coupled and in which the disorder can be added in a controlled manner. We use squeezed light at the input to investigate the effects of nonclassicality and compare the results with those obtained by using conventional classical fields, such as a coherent field and a Gaussian field. Our results show that there is an enhancement in fluctuations of localized light due to the medium's disorder. We find superbunching of the localized light, which may be useful for enhancing the interaction between radiation and matter. Another important consequence of sub-Poissonian statistics of the incoming light is to quench the total fluctuations at the output. Finally, we show that as a result of the multiplicative noise in the problem, the output field is far from Gaussian even if the input is a coherent field.

Thompson, Clinton; Vemuri, Gautam [Department of Physics, Indiana University-Purdue University Indianapolis (IUPUI) Indianapolis, Indiana 46202-3273 (United States); Agarwal, G. S. [Department of Physics, Oklahoma State University, Stillwater, Oklahoma 74078 (United States)

2010-11-15

42

Failure of single-parameter scaling of wave functions in Anderson localization  

NASA Astrophysics Data System (ADS)

We show how to use properties of the vectors which are iterated in the transfer-matrix approach to Anderson localization, in order to generate the statistical distribution of electronic wave-function amplitudes at arbitrary distances from the origin of Ld-1×? disordered systems. For d=1 our approach is shown to reproduce exact diagonalization results available in the literature. In d=2, where strips of width L<=64 sites were used, attempted fits of Gaussian (log-normal) forms to the wave-function amplitude distributions result in effective localization lengths growing with distance, contrary to the prediction from single-parameter scaling theory. We also show that the distributions possess a negative skewness S, which is invariant under the usual histogram-collapse rescaling, and whose absolute value increases with distance. We find 0.15<~-S<~0.30 for the range of parameters used in our study.

Queiroz, S. L.

2002-11-01

43

Anderson localization of a weakly interacting one-dimensional Bose gas  

NASA Astrophysics Data System (ADS)

We consider the phase coherent transport of a quasi-one-dimensional beam of Bose-Einstein condensed particles through a disordered potential of length L . Among the possible different types of flow we identified [T. Paul, P. Schlagheck, P. Leboeuf, and N. Pavloff, Phys. Rev. Lett. 98, 210602 (2007)], we focus here on the supersonic stationary regime where Anderson localization exists. We generalize the diffusion formalism of Dorokhov-Mello-Pereyra-Kumar to include interaction effects. It is shown that interactions modify the localization length and also introduce a length scale L? for the disordered region, above which most of the realizations of the random potential lead to time-dependent flows. A Fokker-Planck equation for the probability density of the transmission coefficient that takes this effect into account is introduced and solved. The theoretical predictions are verified numerically for different types of disordered potentials. Experimental scenarios for observing our predictions are discussed.

Paul, T.; Albert, M.; Schlagheck, P.; Leboeuf, P.; Pavloff, N.

2009-09-01

44

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

SciTech Connect

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

Kravtsov, V. E. [Abdus Salam International Centre for Theoretical Physics, P.O.B. 586, 34100 Trieste (Italy); Yudson, V. I. [Landau Institute for Theoretical Physics, 2 Kosygina St., 117940 Moscow (Russian Federation)

2009-05-14

45

Non-conventional Anderson localization in a matched quarter stack with metamaterials  

NASA Astrophysics Data System (ADS)

We study the problem of non-conventional Anderson localization emerging in bilayer periodic-on-average structures with alternating layers of materials, with positive and negative refraction indices na and nb. Attention is paid to the model of the so-called quarter stack with perfectly matched layers (the same unperturbed by disorder impedances, Za = Zb, and optical path lengths, nada = |nb|db, with da and db being the thicknesses of basic layers). As was recently numerically discovered, in such structures with weak fluctuations of refractive indices (compositional disorder), the localization length Lloc is enormously large in comparison to the conventional localization occurring in the structures with positive refraction indices only. In this paper we develop a new approach, which allows us to derive the expression for Lloc for weak disorder and any wave frequency ?. In the limit ? ? 0 one gets a quite specific dependence, L-1loc??4?8, which is obtained within the fourth order of perturbation theory. We also analyze the interplay between two types of disorder, when in addition to the fluctuations of na and nb, the thicknesses da and db slightly fluctuate as well (positional disorder). We show how conventional localization recovers with the addition of positional disorder.

Torres-Herrera, E. J.; Izrailev, F. M.; Makarov, N. M.

2013-05-01

46

Microscopic derivation of self-consistent equations of Anderson localization in a disordered medium of finite size.  

PubMed

We present a microscopic derivation of self-consistent equations of Anderson localization in a disordered medium of finite size. The derivation leads to a renormalized, position-dependent diffusion coefficient. The position dependence of the latter is due to the position dependence of return probability in a bounded medium. PMID:18517751

Cherroret, N; Skipetrov, S E

2008-04-29

47

Statistics of anomalously localized states at the center of band E = 0 in the one-dimensional Anderson localization model  

NASA Astrophysics Data System (ADS)

We consider the distribution function P(|?|2) of the eigenfunction amplitude at the center-of-band (E = 0) anomaly in the one-dimensional tight-binding chain with weak uncorrelated on-site disorder (the one-dimensional Anderson model). The special emphasis is on the probability of the anomalously localized states (ALS) with |?|2 much larger than the inverse typical localization length ?0. Using the recently found solution for the generating function ?an(u, ?) we obtain the ALS probability distribution P(|?|2) at |?|2?0 ? 1. As an auxiliary preliminary step, we found the asymptotic form of the generating function ?an(u, ?) at u ? 1 which can be used to compute other statistical properties at the center-of-band anomaly. We show that at moderately large values of |?|2?0, the probability of ALS at E = 0 is smaller than at energies away from the anomaly. However, at very large values of |?|2?0, the tendency is inverted: it is exponentially easier to create a very strongly localized state at E = 0 than at energies away from the anomaly. We also found the leading term in the behavior of P(|?|2) at small |?|2 ? ?-10 and show that it is consistent with the exponential localization corresponding to the Lyapunov exponent found earlier by Kappus and Wegner.

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

2013-01-01

48

Exact solution for eigenfunction statistics at the center-of-band anomaly in the Anderson localization model  

NASA Astrophysics Data System (ADS)

An exact solution is found for the problem of the center-of-band (E=0) anomaly in the one-dimensional Anderson model of localization. By deriving and solving an equation for the generating function ?(u,?) we obtained an exact expression in quadratures for statistical moments Iq=?|?E(r)|2q? of normalized wave functions ?E(r) which show violation of one-parameter scaling and emergence of an additional length scale at E?0 .

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

2010-11-01

49

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

NASA Astrophysics Data System (ADS)

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?E, where a is the lattice constant and ?E is the de Broglie wavelength. We develop a regular approach to anomalous statistics of normalized eigenfunctions ?(r) at such commensurability points. The approach is based on an exact integral transfer-matrix equation for a generating function ?r(u, ?) (u and ? 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=pq with q > 2. The descender of the generating function Pr(?)??r(u=0,?) 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 ?(u, ?) at the E = 0 (f=12) anomaly. This equation is nonseparable in variables u and ?. Yet, we show that due to a hidden symmetry, it is integrable and we construct an exact solution for ?(u, ?) explicitly in quadratures. Using this solution we computed moments Im = N (m ? 1) for a chain of the length N ? ? 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.

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

2011-07-01

50

Universal aspects of localized excitations in graphene  

NASA Astrophysics Data System (ADS)

Unique features of nonlinear solitary plasmon excitations in two and three dimensional massless Dirac fluids, with respect to their normal Fermi counterparts, are explored using the Bernoulli pseudopotential method. It is revealed that graphene, as a two dimensional Dirac fluid, possesses some unique characteristics with respect to the propagation of the localized plasmon excitations, which is absent in other ordinary solids. It is also shown that the Mach number limit below/above, which the localized solitary/periodic excitations propagate in a monolayer graphene has a universal value independent of the other environmental parameters such as the electron number-density and the ambient temperature. The amplitude of nonlinear solitary or periodic waves is also remarked to be independent of such parameters and depend only on the Mach-number value of the solitary or periodic excitations. These unique hydrodynamic wave features of the massless Dirac fluid are attributed to the remarkable photon-like linear energy dispersion in Dirac points of graphene material.

Akbari-Moghanjoughi, M.

2013-08-01

51

Numerical renormalization group study of probability distributions for local fluctuations in the Anderson-Holstein and Holstein-Hubbard models.  

PubMed

We show that information on the probability density of local fluctuations can be obtained from a numerical renormalization group calculation of a reduced density matrix. We apply this approach to the Anderson-Holstein impurity model to calculate the ground state probability density ?(x) for the displacement x of the local oscillator. From this density we can deduce an effective local potential for the oscillator and compare its form with that obtained from a semiclassical approximation as a function of the coupling strength. The method is extended to the infinite dimensional Holstein-Hubbard model using dynamical mean field theory. We use this approach to compare the probability densities for the displacement of the local oscillator in the normal, antiferromagnetic and charge ordered phases. PMID:21389469

Hewson, Alex C; Bauer, Johannes

2010-02-23

52

Interference of locally excited surface plasmons  

SciTech Connect

Surface plasmon interactions on a finite silver layer are theoretically investigated using a coupled dipole formalism. The studied system consists of several protruding particles located on the surface of the layer that are scanned with an optical probe. An optical scan-image of the silver surface is obtained by assigning the recorded far-field radiation to the momentary position of the optical probe. Both, probe and protrusions are considered as single dipolar particles. Interferences of the locally excited surface plasmons can be recorded by detecting the radiation emitted into the lower half-space at angles beyond the critical angle of total internal reflection (forbidden light). The resulting scan images show excellent agreement with recent experimental measurements. The theory of the coupled dipole formalism using Green`s functions of a layered reference system is outlined and electromagnetic properties of surface plasmons are discussed. {copyright} {ital 1997 American Institute of Physics.}

Novotny, L. [Swiss Federal Institute of Technology, ETH Zuerich, CH-8092 Zuerich (Switzerland); Hecht, B.; Pohl, D.W. [IBM Research Division, Zurich Research Laboratory, CH-8803 Rueschlikon (Switzerland)

1997-02-01

53

Ground State of Anderson Hamiltonian  

NASA Astrophysics Data System (ADS)

Following the Wiegmann approach the exact expression of the ground state energy for the symmetric Anderson Hamiltonian was obtained. In this paper the calculation is done for the asymmetric Anderson Hamiltonian, of the ground state energy, of the average number of localized electrons and of the charge susceptibility.

Kawakami, Norio; Okiji, Ayao

1982-04-01

54

Anderson Localization Triggered by Spin Disorder—With an Application to Eu x Ca1- x B6  

NASA Astrophysics Data System (ADS)

The phenomenon of Anderson localization is studied for a class of one-particle Schrödinger operators with random Zeeman interactions. These operators arise as follows: Static spins are placed randomly on the sites of a simple cubic lattice according to a site percolation process with density x and coupled to one another ferromagnetically. Scattering of an electron in a conduction band at these spins is described by a random Zeeman interaction term that originates from indirect exchange. It is shown rigorously that, for positive values of x below the percolation threshold, the spectrum of the one-electron Schrödinger operator near the band edges is dense pure-point, and the corresponding eigenfunctions are exponentially localized. Localization near the band edges persists in a weak external magnetic field, H, but disappears gradually, as H is increased. Our results lead us to predict the phenomenon of colossal (negative) magnetoresistance and the existence of a Mott transition, as H and/or x are increased. Our analysis is motivated directly by experimental results concerning the magnetic alloy Eu x Ca1- x B6.

Egli, Daniel; Fröhlich, Jürg; Ott, Hans-Rudolf

2011-06-01

55

Magnetoresistance of an Anderson insulator of bosons.  

PubMed

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)~B(4/5). 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. PMID:23889427

Gangopadhyay, Anirban; Galitski, Victor; Müller, Markus

2013-07-09

56

Screened Anderson model  

Microsoft Academic Search

The occupation number ({ital n}{sub {ital f}}) of the impurity orbital ({ital f}) in the Anderson model is calculated as a function of the orbital energy ({var epsilon}{sub {ital f}}), taking into account finite values for the Coulomb interactions between the impurity and the conduction electrons ({ital G}) and between two electrons inside of the localized orbital ({ital U}). For

H. O. Frota; G. D. Mahan

1991-01-01

57

Suppression of Anderson localization of light in one-dimensional disordered photonic superlattices  

NASA Astrophysics Data System (ADS)

The localization properties of electromagnetic modes in one-dimensional disordered photonic superlattices are theoretically studied. The multilayered system is considered to be composed of alternating stacks of two different random-thickness slabs, characterized by nondispersive and/or frequency-dependent electric permittivities and magnetic permeabilities. Results for the localization length are evaluated by using an analytical model for weakly disordered systems as well as its general definition through the transmissivity properties of the heterostructure. Good agreement between both results is observed only for small amplitudes of disorder. The critical frequencies at which the localization length diverges are correctly predicted in the whole frequency spectrum by the analytical model and confirmed via the corresponding numerical calculations. The ?2 dependence of the localization length, previously observed in disordered heterostructures made of material of positive refractive indexes, are confirmed in the present work. In addition, new ?4 and ?-4 dependencies of the localization length in positive-negative disordered photonic superlattices are obtained, under certain specific conditions, in the long and short wavelength limits, respectively. The asymptotic behavior of the localization length in these limits is essentially determined by the particular frequency dispersion that characterizes the metamaterial used in the left-handed layers. When the effects of absorption are considered, then a divergence of the localization length is still observed, under some conditions, in the short wavelength limit.

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

2012-05-01

58

Usual Anderson localization restored in bilayered left- and right-handed structures  

NASA Astrophysics Data System (ADS)

We present a study of the attenuation length in a one-dimensional array of alternating left- and right-handed materials in which both the permittivities and the permeabilities are disordered. This type of structure has been shown to present an anomaly in the attenuation length when only permeabilities are disordered. We derive a simple analytical expression of the attenuation length, when the disorder in the refraction index is due to perturbations in both the permeability and the permittivity. Our expression is able to explain the transition to the anomalous behavior when perturbation only in the permeability or only in the permittivity is considered. Besides, we show that the anomaly is dramatically affected when considering perturbations in permeability and permittivity. The coupling effects are able to restore the ordinary localization length.

Maurel, Agnès; Ourir, Abdelwaheb; Mercier, Jean-François; Pagneux, Vincent

2012-05-01

59

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

SciTech Connect

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

Basko, D.M., E-mail: denis.basko@grenoble.cnrs.fr [Laboratoire de Physique et Modelisation des Milieux Condenses, Universite de Grenoble 1 and CNRS, BP166, 38042 Grenoble (France)

2011-07-15

60

Screened Anderson model  

Microsoft Academic Search

The occupation number (nf) of the impurity orbital (f) in the Anderson model is calculated as a function of the orbital energy (?f), taking into account finite values for the Coulomb interactions between the impurity and the conduction electrons (G) and between two electrons inside of the localized orbital (U). For small values of G, the transitions f2-->f1-->f0 occur, with

H. O. Frota; G. D. Mahan

1991-01-01

61

Subwavelength Localization of Atomic Excitation Using Electromagnetically Induced Transparency  

NASA Astrophysics Data System (ADS)

We report an experiment in which an atomic excitation is localized to a spatial width that is a factor of 8 smaller than the wavelength of the incident light. The experiment utilizes the sensitivity of the dark state of electromagnetically induced transparency (EIT) to the intensity of the coupling laser beam. A standing-wave coupling laser with a sinusoidally varying intensity yields tightly confined Raman excitations during the EIT process. The excitations, located near the nodes of the intensity profile, have a width of 100 nm. The experiment is performed using ultracold Rb87 atoms trapped in an optical dipole trap, and atomic localization is achieved with EIT pulses that are approximately 100 ns long. To probe subwavelength atom localization, we have developed a technique that can measure the width of the atomic excitations with nanometer spatial resolution.

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

2013-07-01

62

The Anderson Quin Cycle  

Microsoft Academic Search

The objective of this study was to make a more refined evaluation of the Anderson Quin Cycle based on most recent information on the performance of various elements that will be used in the Anderson Quin Cycle. My original estimate of the work plan for evaluating and optimizing the Anderson Quin Cycle called for 7000 man hours of work. Since

J. H. Anderson; W. M. Bilbow

1993-01-01

63

Exciting and probing plasmons in graphene by local defects  

NASA Astrophysics Data System (ADS)

The short wavelength of collective excitations, i.e., plasmons, in doped graphene (˜10-20 nm) is very attractive for multiple applications. However, the same short wavelength makes photoexcitation of plasmons in graphene a very challenging task. In this work, we discuss various types of local defects including semiconductor quantum dots, metallic nanoclusters, edges and holes in graphene as means to ``squeeze'' the large wavelength of optical excitation down to the nanometer scale, thus, providing an effective coupling between free photons and plasmons in graphene. In the case of semiconductor quantum dots, we show how plasmons in graphene can be excited and probed by Forster resonance energy transfer from the optically excited quantum dot to the graphene sheet. Specifically, we demonstrate how the calculated dispersion relation of plasmons in graphene as well as of other electronic excitations can be accurately extracted by controlling the backgate voltage and the distance between the quantum dot and graphene [1]. [4pt] [1] K. A. Velizhanin, A. Efimov``Probing plasmons in graphene by resonance energy transfer,'' Phys. Rev. B, 085401, 84 (2011).

Efimov, Anatoly; Velizhanin, Kirill

2012-02-01

64

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

PubMed

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

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

2011-06-02

65

Localized hole effects in inner-shell excitation  

SciTech Connect

Ab initio calculations of valence shell ionization potentials have shown that orbital relaxation and correlation differences usually make contributions of comparable magnitude. In marked contrast to this observation is the situation for deep core ionization, where correlation differences (approx. 1 eV) play a relatively minor role compared to orbital relaxation (approx. 20 eV). Theoretical calculations have shown that this relaxation is most easily described if the 1s-vacancy created by a K-shell excitation is allowed to localize on one of the atomic centers. For molecules possessing a center of inversion, this means that the molecular orbitals that best describe the final state do not transform as any irreducible representation of the molecular point group. Recent experimental work by Shaw, King, Read and Cvejanovic and by Stefani and coworkers has prompted us to carry out further calculations on N/sub 2/, as well as analogous investigations of 1s/sub N/ ..-->.. ..pi..* excitation in NO and N/sub 2/O. The generalized oscillator strengths display a striking similarity and point to the essential correctness of the localized hole picture for N/sub 2/. The theoretical calculations are briefly described, followed by a summary of the results and comparison to experiment, followed by a short discussion.

Rescigno, T.N.; Orel, A.E.

1983-10-14

66

The Bootstrap Multiscale Analysis for the Multi-particle Anderson Model  

NASA Astrophysics Data System (ADS)

We extend the bootstrap multi-scale analysis developed by Germinet and Klein to the multi-particle Anderson model, obtaining Anderson localization, dynamical localization, and decay of eigenfunction correlations.

Klein, Abel; Nguyen, Son T.

2013-06-01

67

Predicted mobility edges in one-dimensional incommensurate optical lattices: an exactly solvable model of anderson localization.  

PubMed

Localization properties of noninteracting quantum particles in one-dimensional incommensurate lattices are investigated with an exponential short-range hopping that is beyond the minimal nearest-neighbor tight-binding model. Energy dependent mobility edges are analytically predicted in this model and verified with numerical calculations. The results are then mapped to the continuum Schrödinger equation, and an approximate analytical expression for the localization phase diagram and the energy dependent mobility edges in the ground band is obtained. PMID:20366867

Biddle, J; Das Sarma, S

2010-02-19

68

Proposed signature of Anderson localization and correlation-induced delocalization in an N-leg optical lattice  

SciTech Connect

We propose a realization of the one-dimensional random dimer model and certain N-leg generalizations using cold atoms in an optical lattice. We show that these models exhibit multiple delocalization energies that depend strongly on the symmetry properties of the corresponding Hamiltonian, and we provide analytical and numerical results for the localization length as a function of energy. We demonstrate that the N-leg systems possess similarities with their one-dimensional ancestors but are demonstrably distinct. The existence of critical delocalization energies leads to dips in the momentum distribution that serve as a clear signal of the localization-delocalization transition. These momentum distributions are different for models with different group symmetries and are identical for those with the same symmetry.

Sedrakyan, T. A.; Kestner, J. P.; Das Sarma, S. [Condensed Matter Theory Center, Department of Physics, University of Maryland, College Park, Maryland 20742 (United States); Joint Quantum Institute, Department of Physics, University of Maryland, College Park, Maryland 20742 (United States)

2011-11-15

69

Controlling the localization and migration of optical excitation  

NASA Astrophysics Data System (ADS)

In the nanoscale structure of a wide variety of material systems, a close juxtaposition of optically responsive components can lead to the absorption of light by one species producing fluorescence that is clearly attributable to another. The effect is generally evident in systems comprising two or more light-absorbing components (molecules, chromophores or quantum dots) with well-characterised fluorescence bands at similar, differentiable wavelengths. This enables the fluorescence associated with transferred energy to be discriminated against fluorescence from an initially excited component. The fundamental mechanism at the heart of the phenomenon, molecular (resonance) energy transfer, also operates in systems where the product of optical absorption is optical frequency up-conversion. In contrast to random media, structurally organised materials offer the possibility of pre-configured control over the delocalization of energy, through molecular energy transfer following optical excitation. The Förster mechanism that conveys energy between molecular-scale components is strongly sensitive to specific forms of correlation between the involved components, in terms of position, spectroscopic character, and orientation; one key factor is a spectroscopic gradient. Suitably designed materials offer a broad scope for the widespread exploitation of such features, in applications ranging from chemical and biological sensing to the detection of nanoscale motion or molecular conformations. Recently, attention has turned to the prospect of actively controlling the process of energy migration, for example by changing the relative efficiencies of fluorescence and molecular energy transfer. On application of static electric fields or off-resonant laser light - just two of the possibilities - each represents a means for achieving active control with ultrafast response, in suitably configured systems. As the principles are established and the theory is developed, a range of new possibilities for technical application is emerging. For example, applications can be envisaged for new forms of all-optical switching and transistor action. There is also interest in engaging with the interplay of optical excitation and local nanoscale force, exploiting local responses to changes in dispersion forces, accompanying molecular energy transfer.

Andrews, David L.; Bradshaw, David S.

2012-09-01

70

Local excitation and local collection of photocurrent in thin-film polycrystalline photovoltaic devices  

NASA Astrophysics Data System (ADS)

The power conversion efficiency of commercial solar modules based on thin-film chalcogenide materials is well below the theoretical limits. To understand the underlying physical mechanisms limiting the efficiency, we investigate local photovoltaic properties isolating the difference between the grain bulk (0.5-2 mkm in size) and the grain boundary in CdTe absorber. Local current-voltage measurements are performed using nano-contacts in conjunction with local electron-hole pairs generation comparing multiple injection techniques. First, the carriers are excited using variable energy electron beam enabling measurements with a spatial resolution down to 20 nm. Second, we have developed a novel approach for high-resolution and high-throughput photocurrent imaging downconverting electron beam into a near-field optical source using a thin film (50 nm) of phosphors. The electron beam is fully absorbed in the phosphors layer, and the cathodoluminescence is used as a local photon source. Third, we generate carriers using a near-filed optical microscope varying the excitation wavelength. The results show that, in a well-optimized material, a large fraction of grain boundaries displays higher photocurrent as compared to grain bulk effectively serving as a three-dimensional distributed photocurrent collector.

Zhitenev, Nikolai; Yoon, Heayoung; Leite, Marina; Lee, Youngmin; Ko, Sarah; Zhao, Yue; Gianfrancesco, Anthony; Haney, Paul; Talin, Alec

2013-03-01

71

Localized vibrational and electronic excitations of impurities in compound semiconductors  

NASA Astrophysics Data System (ADS)

Two types of localized vibrational modes of oxygen substituting for Te in CdTe, i.e., OTe, are reported. In one, OTe is associated with a nearest neighbor (NN) vacancy as a (OTe - VCd) center and hence with C3v symmetry, with its uniaxial axis along <111>, whereas in the other O Te is surrounded by all the four NN Cd's and thus possesses Td site symmetry. By an appropriate control of stoichiometry it is possible to reproducibly generate the formation of either (OTe - VCd) or OTe centers. These configurations are deduced from their ultrahigh resolution infrared signatures. For the (O Te - VCd) centers, consistent with their uniaxial symmetry, a pair of sharp local vibrational modes (LVM) are observed at n1 = 1096.78 cm-1 and n2 = 1108.35 cm-1, the latter nearly twice as intense as the former. In the LVM spectrum of OTe centers with the full complement of NN Cd's, consistent with its Td symmetry, only one LVM signature appears at n0 = 349.79 cm-1. With the increasing temperature, n1 and n2 approach each other and coalesce into a single triply degenerate line at n*0 for temperature T ? T* ˜ 300 K; the uniaxial (C3v) symmetry of (OTe - VCd) transforms to T d symmetry at T* and above, acquired by the (OTe - VCd) centers due to the increasing rate of bond switching among the four possible OTe - VCd <111> directions as T approaches T*. The (OTe - VCd) centers also display a fascinating pair of second harmonics including a coalescence at T* and beyond. We have discovered two types of localized vibrational modes (LVMs) of oxygen related defect centers in stoichiometrically controlled CdSe, a wurtzite crystal. In one, oxygen substitutionally replaces Cd (OCd) as an anti-site impurity with C3v site symmetry. Consistent with its uniaxial configuration, under relatively low resolution a pair of sharp LVMs is observed at mu1 = 1991.77 cm-1 and mu2 = 2001.3 cm-1. Under high resolution, both mu1 and mu2 display a remarkable fine structure which can be traced to the motion of the nearest neighbor Se atoms surrounding the OCd in which oxygen replacing Cd is an anti-site impurity. The host isotopic fine structure is strongly reminiscent of the LVMs of CdSe observed with MgCd impurities. In both cases, the fine structure is associated with nearest neighbor Se atoms set in vibratory motion by the LVMs of OCd or MgCd. In the other, oxygen substitutionally replaces Se (OSe) in the vicinity of a Cd vacancy, labeled as (OSe - VCd) centers, in which the nearest neighbor Cd vacancy occurs on one of three vertical planes of reflection on which OSe also lies. The center displays a local C s symmetry resulting in three infrared absorption peaks at gamma 1 = 1094.11 cm-1, gamma2 = 1107.45 cm -1, and gamma3 = 1126.33 cm-1. With increasing temperature, gamma1 and gamma2 approach each other and coalesce into a single doubly degenerate mode at T 1 ˜ 480 K; the Cs site symmetry of (OSe - VCd) thus transforms to C3v symmetry at higher temperatures, acquired by the increasing rate of bond switching among the three equivalent positions for VCd. At even higher temperatures, gamma3 merges with gamma1 and gamma2 into a single mode at T2 ˜ 560 K; the acquired C 3v site symmetry of (OSe - VCd) further transforms to a quasi-Td symmetry due to the same mechanism. The group IB impurities (Cu, Ag, and Au) incorporated into II-VI zinc blende hosts of ZnTe and CdTe exhibit well resolved excitation lines followed by a photoionization continuum in their infrared absorption spectra. They are associated with transitions from a "1s-like" ground state to various "p-like" excited state characteristic of a hole bound to a Coulomb center. Their spacing agree well with those predicted in the effective mass theory for single acceptors as expected for group IB elements substitutionally replacing the group IIB cations of the host. The occurrence of the simultaneous excitation of the Lyman transitions in combination with the zone center longitudinal optical phonon and hence lying in the photoionization continuum and displaying Fano-like asymme

Chen, Gang

72

Modeling of ion-acoustic soliton excitation through decay process of a localized perturbation  

Microsoft Academic Search

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

H. Hakimi Pajouh; H. Abbasi

2008-01-01

73

Quantifying Anderson's fault types  

Microsoft Academic Search

Anderson [1905] explained three basic types of faulting (normal, strike-slip, and reverse) in terms of the shape of the causative stress tensor and its orientation relative to the Earth's surface. Quantitative parameters can be defined which contain information about both shape and orientation [Célérier, 1995], thereby offering a way to distinguish fault-type domains on plots of regional stress fields and

Robert W. Simpson

1997-01-01

74

The Anderson Quin Cycle  

SciTech Connect

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

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

1993-03-18

75

The acoustic blink reflex: Stimulus dependence, excitability and localizing value  

Microsoft Academic Search

The acoustic blink reflex was examined in 26 subjects with open eyes and 20 subjects with closed eyes by means of an electrooculogram. Amplitude and excitability are highly dependent on the loudness of the stimulus used and on the opening or closure of the eyelids. Particularly if the eyes are closed, it may be necessary to use a stimulus of

W. Sfiring; D. von Cramon

1981-01-01

76

Movability of localized excitations in nonlinear discrete systems: A separatrix problem  

Microsoft Academic Search

We analyze the effect of internal degrees of freedom on the movability properties of localized excitations on nonlinear Hamiltonian lattices by means of properties of a local phase space which is at least of dimension six. We formulate generic properties of a movability separatrix in this local phase space. We prove that due to the presence of internal degrees of

S. Flach; C. R. Willis

1994-01-01

77

Simplicity of eigenvalues in Anderson-type models  

NASA Astrophysics Data System (ADS)

We show almost sure simplicity of eigenvalues for several models of Anderson-type random Schrödinger operators, extending methods introduced by Simon for the discrete Anderson model. These methods work throughout the spectrum and are not restricted to the localization regime. We establish general criteria for the simplicity of eigenvalues which can be interpreted as separately excluding the absence of local and global symmetries, respectively. The criteria are applied to Anderson models with matrix-valued potential as well as with single-site potentials supported on a finite box.

Naboko, Sergey; Nichols, Roger; Stolz, Günter

2013-04-01

78

Topological Anderson insulator.  

PubMed

Disorder plays an important role in two dimensions, and is responsible for striking phenomena such as metal-insulator transition and the integral and fractional quantum Hall effects. In this Letter, we investigate the role of disorder in the context of the recently discovered topological insulator, which possesses a pair of helical edge states with opposing spins moving in opposite directions and exhibits the phenomenon of quantum spin Hall effect. We predict an unexpected and nontrivial quantum phase termed "topological Anderson insulator," which is obtained by introducing impurities in a two-dimensional metal; here disorder not only causes metal-insulator transition, as anticipated, but is fundamentally responsible for creating extended edge states. We determine the phase diagram of the topological Anderson insulator and outline its experimental consequences. PMID:19392389

Li, Jian; Chu, Rui-Lin; Jain, J K; Shen, Shun-Qing

2009-04-01

79

Anderson-Fabry Disease  

Microsoft Academic Search

Anderson-Fabry disease is a multisystemic lysosomal storage disorder due to a deficiency of ?-galactosidase A resulting in\\u000a an accumulation of neutral glycosphingolipids. Due to its rare occurrence the disease is often misdiagnosed or the correct\\u000a diagnose is delayed for many years (Weidemann et al. 2008). Dermatologists except ophthalmologists play the most important role for early diagnosis of this disorder, which

Anna-Christine Hauser

80

Interface localization of light in disordered photonic lattices  

NASA Astrophysics Data System (ADS)

The Anderson localization of light at the interface separating square and hexagonal photonic lattices is demonstrated numerically. The influence of varying lattice intensities and disorder level on the transverse localization of light is discussed. Both suppression and enhancement of light localization in the presence of the interface, depending on the difference in the lattice intensity in both regions, and the position of the excited lattice site are demonstrated. Such localization is compared to the cases with no interfaces. Also, it is analysed how the presence of a phase-slip defect modifies the phenomenon of Anderson localization of light at the interface.

Jovi?, Dragana

2013-07-01

81

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

SciTech Connect

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

Kormos, Marton; Chou Yangzhi; Imambekov, Adilet [Department of Physics and Astronomy, Rice University, Houston, Texas 77005 (United States)

2011-12-02

82

Localized d-d excitations in NiO(100) and CoO(100)  

Microsoft Academic Search

The localized character of the 3d electrons in the antiferromagnetic oxides NiO(100) and CoO(100) has been studied with electron energy-loss spectroscopy at primary energies between 20 and 1200 eV. The spectra of both charge-transfer compounds exhibit weak but sharp loss structures within the insulating gap region due to crystal-field excitations of the 3dn configuration (dn-->dn*). These parity forbidden d-d excitations

A. Gorschlüter; H. Merz

1994-01-01

83

Model supercell local-density calculations of the 3d excitation spectra in NiO  

Microsoft Academic Search

The local-density supercell impurity approach is used to calculate the excitation spectra due to the emission and absorption of a 3d electron in the Mott insulator NiO. Good agreement is found with both photoemission (PES) and inverse photoemission (bremsstrahlung isochromat spectroscopy (BIS)) data. In particular, a BIS excitation gap of 4.1 eV is found compared to 4.3 eV experimentally. The

M. R. Norman; A. J. Freeman

1986-01-01

84

Model supercell local-density calculations of the 3d excitation spectra in NiO  

Microsoft Academic Search

The local-density supercell impurity approach is used to calculate the excitation spectra due to the emission and absorption of a 3d electron in the Mott insulator NiO. Good agreement is found with both photoemission (PES) and inverse photoemission [bremsstrahlung isochromat spectroscopy (BIS)] data. In particular, a BIS excitation gap of 4.1 eV is found compared to 4.3 eV experimentally. The

M. R. Norman; A. J. Freeman

1986-01-01

85

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

NASA Astrophysics Data System (ADS)

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

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

2008-10-01

86

Stochastic resonance in a locally excited system of bistable oscillators  

NASA Astrophysics Data System (ADS)

Stochastic resonance is studied in a one-dimensional array of overdamped bistable oscillators in the presence of a local subthreshold periodic perturbation. The system can be treated as an ensemble of pseudospins tending to align parallel which are driven dynamically by an external periodic magnetic field. The oscillators are subjected to a dynamic white noise as well as to a static topological disorder. The latter is quantified by the fraction of randomly added long-range connections among ensemble elements. In the low connectivity regime the system displays an optimal global stochastic resonance response if a small-world network is formed. In the mean-field regime we explain strong changes in the dynamic disorder strength provoking a maximal stochastic resonance response via the variation of fraction of long-range connections by taking into account the ferromagnetic-paramagnetic phase transition of the pseudospins. The system size analysis shows only quantitative power-law type changes on increasing number of pseudospins.

Gosak, M.; Perc, M.; Kralj, S.

2011-04-01

87

Photoemission spectroscopy for the spin-degenerate Anderson model  

Microsoft Academic Search

A procedure that calculates excitation properties for the Anderson model is reported and applied to photoemission. In the mixed-valence regime, hybridized in the ground state, the one- and two-electron impurity configurations generate two spectral resonances. In the Kondo regime, a phenomenological expression describes the narrow peak at the Fermi level.

H. O. Frota; L. N. Oliveira

1986-01-01

88

Dynamics of 1-D Chains of Magnetic Vortices in Response to Local and Global Excitations  

Microsoft Academic Search

We report the magnetic vortex dynamics of 1-D chains of nanomagnetic disks under a time-dependent magnetic field localized at one end of the chain. The transmission of the peak amplitude of the gyrotropic excitation mode of the vortex core along the chain has been actively controlled by manipulating the geometry and condition of preparation of the magnetic ground states of

Saswati Barman; Anjan Barman; Yoshichika Otani

2010-01-01

89

Manipulation of graphene’s dynamic ripples by local harmonic out-of-plane excitation  

NASA Astrophysics Data System (ADS)

With use of carefully designed molecular dynamics simulations, we demonstrate tuning of dynamic ripples in free standing, thermally fluctuating graphene by applying a local out-of-plane sinusoidal excitation. The local dynamic morphology can be controlled via varying external modulation and the boundary conditions. We fully account for the discrete atomistic structure of graphene, as well as natural energy dissipation due in part to its remarkably high thermal conductivity. In addition to stable dynamic rippling patterns, we observed an unexpected flattening of graphene well below the thermal limit. Our results provide insight into the dynamic response of atomically thin layers to an external time-varying excitation in the presence of realistic thermal fluctuations and energy loss. This suggests intriguing possibilities for modulating the electrical and optical properties of atomically thin membranes via local dynamic morphology control. Contribution of the National Institute of Standards and Technology, an agency of the US government. Not subject to copyright in the USA.

Smolyanitsky, A.; Tewary, V. K.

2013-02-01

90

Manipulation of graphene's dynamic ripples by local harmonic out-of-plane excitation.  

PubMed

With use of carefully designed molecular dynamics simulations, we demonstrate tuning of dynamic ripples in free standing, thermally fluctuating graphene by applying a local out-of-plane sinusoidal excitation. The local dynamic morphology can be controlled via varying external modulation and the boundary conditions. We fully account for the discrete atomistic structure of graphene, as well as natural energy dissipation due in part to its remarkably high thermal conductivity. In addition to stable dynamic rippling patterns, we observed an unexpected flattening of graphene well below the thermal limit. Our results provide insight into the dynamic response of atomically thin layers to an external time-varying excitation in the presence of realistic thermal fluctuations and energy loss. This suggests intriguing possibilities for modulating the electrical and optical properties of atomically thin membranes via local dynamic morphology control. PMID:23306970

Smolyanitsky, A; Tewary, V K

2013-01-11

91

A characterization of the Anderson metal-insulator transport transition  

Microsoft Academic Search

We investigate the Anderson metal-insulator transition for random Schrodinger operators. We define the strong insulator region to be the part of the spectrum where the random operator ex- hibits strong dynamical localization in the Hilbert-Schmidt norm. We introduce a local transport exponent ?(E), and set the metallic trans- port region to be the part of the spectrum with nontrivial transport

Francois Germinet; Abel Klein

2001-01-01

92

Localized short impulses in a nerve model with self-excitable membrane.  

PubMed

During the generation and transmission of nerve impulses, the cytoplasm behaves like an excitable medium that self-regulates the shapes and magnitudes of the output excitation. In connection with this self-regulatory function, one can readily think of the plasma membrane as a nerve organ holding the key role in the mechanisms of generation and transmission of the transmembrane potential, namely, it is expected to provide the essential feedback that stabilizes the stimulus. Here, a simple and coherent picture of self-regulation of the nerve impulse is proposed in terms of one single feedback associated with the main excitable biological organ of the nervous system. In this purpose, an electrodynamic theory is developed within the framework of a cable model in which the membrane capacitor is regarded as a charge-management electrical component with a defined capacity-voltage characteristic. It is found that in both myelinated and myelin-free nerve fiber contexts, the transmembrane excitations are well-localized short impulses whose shape and stability are determined by the capacity-voltage characteristic assumed to govern the self-excitability properties of the nerve membrane. PMID:19905339

Dikandé, Alain M; Bartholomew, Ga-Akeku

2009-10-05

93

Localized short impulses in a nerve model with self-excitable membrane  

NASA Astrophysics Data System (ADS)

During the generation and transmission of nerve impulses, the cytoplasm behaves like an excitable medium that self-regulates the shapes and magnitudes of the output excitation. In connection with this self-regulatory function, one can readily think of the plasma membrane as a nerve organ holding the key role in the mechanisms of generation and transmission of the transmembrane potential, namely, it is expected to provide the essential feedback that stabilizes the stimulus. Here, a simple and coherent picture of self-regulation of the nerve impulse is proposed in terms of one single feedback associated with the main excitable biological organ of the nervous system. In this purpose, an electrodynamic theory is developed within the framework of a cable model in which the membrane capacitor is regarded as a charge-management electrical component with a defined capacity-voltage characteristic. It is found that in both myelinated and myelin-free nerve fiber contexts, the transmembrane excitations are well-localized short impulses whose shape and stability are determined by the capacity-voltage characteristic assumed to govern the self-excitability properties of the nerve membrane.

Dikandé, Alain M.; Bartholomew, Ga-Akeku

2009-10-01

94

Different responses of localized and extended excitons to exciton{endash}exciton scattering manifested in excitation density-dependent photoluminescence excitation spectra  

SciTech Connect

Excitation density-dependent photoluminescence excitation (PLE) measurements are performed for a disordered two-dimensional (2D) In{sub 0.40}Ga{sub 0.60}As/GaAs(311)B quantum dot superlattice (QDSL) containing localized and extended states separated by a mobility edge. For low excitation densities, the PLE spectrum is independent of excitation density. In the extended state region, it takes the shape of the absorption spectrum of the 2D QDSL. With increasing excitation density, the PLE spectral shape is dramatically changed. For excitation densities at which the state filling can be excluded, it is found that the different responses of localized and extended excitons to exciton{endash}exciton scattering are responsible for the observed change in the PLE spectrum. A qualitative explanation for the evolution of the PLE spectrum is presented based on the excitation density-dependent capture, relaxation and recombination times obtained previously in time-resolved photoluminescence (TRPL) experiments. The mobility edge extracted from the modification of the PLE spectrum is in good agreement with that determined by TRPL measurements. To show the effect of coupling strength, a comparison of the excitation density-dependent PLE spectra is made between the 2D QDSL and a weekly coupled quantum dot array. It further confirms the existence of highly extended states in the 2D QDSL. {copyright} 2001 American Institute of Physics.

Lan, Sheng; Nishikawa, Satoshi; Wada, Osamu; Akahane, Kouichi; Okada, Yoshitaka; Kawabe, Mitsuo

2001-06-01

95

Many-Body Theory of Effective Local Potentials for Electronic Excitations. I  

Microsoft Academic Search

We compare the Hartee-Fock (HF), Talman-Shadwick (TS), exact Slater (S), Slater Xalpha, and local-density (LD) schemes, and investigate how well the associated one-electron potentials describe electronic excitations. We discuss in some detail the role of self-interaction in the different schemes, and demonstrate that the Xalpha and LD schemes effectively represent ionic (VN-1) potentials in the core region. In fact, for

Z. Crljen; G. Wendin

1985-01-01

96

Intrinsic localized excitations in nonlinear lattices: Heuristic explanation for the nature of polar nanoregions?  

NASA Astrophysics Data System (ADS)

The study is addressed to a topical problem of self-localization in condensed state with special emphasis on a class of complex oxides categorized as ferroelectric relaxors. Basically, their anomalous temperature response is associated with the dynamics of microscopic scale polar regions supported by somewhat artificial metastable configurations. A unified approach to the spontaneous emergence and stability of the polar nanoregions is assigned to intrinsic localized excitations in Hamiltonian lattices with nonlinearity and non-Gibbsian statistics as necessary and sufficient ingredients of the theory.

Klotins, E.

2010-01-01

97

Ab initio theory for treating local electron excitations in molecules and its performance for computing optical properties.  

PubMed

In this article, as a first step to develop an efficient approximation for predicting the molecular electronic excited state properties at ab initio level, we propose local excitation approximation (LEA). In the LEA scheme, the only local electron excitations within selected substructure (Chromophore) are treated to calculate the targeted excited state wavefunctions, whereas the other electron excitations (local electron excitations in other substructure and charge-transfer excitations between different regions) are simply discarded. This concept is realized by using the localized molecular orbitals (LMO) localizing on the chromophore substructure. If the targeted transitions show the strong local character and the adequate substructure is selected as chromophore region, the LEA scheme can provide excited state properties without large loss of accuracy. The fatal slowdown of convergence speed of Davidson's iterative diagonalization due to the use of LMO can be avoided by additional transformation of LMOs. To assess the accuracy and efficiency of the LEA scheme, we performed test calculations using various compounds at configuration interaction single (CIS) and time-dependent Hartree-Fock (TDHF) level of theory. PMID:19266480

Miura, Masanori; Aoki, Yuriko

2009-11-15

98

Critical Behavior at the Mott-Anderson Transition: A Typical-Medium Theory Perspective  

NASA Astrophysics Data System (ADS)

We present a detailed analysis of the critical behavior close to the Mott-Anderson transition. Our findings are based on a combination of numerical and analytical results obtained within the framework of typical-medium theory—the simplest extension of dynamical mean field theory capable of incorporating Anderson localization effects. By making use of previous scaling studies of Anderson impurity models close to the metal-insulator transition, we solve this problem analytically and reveal the dependence of the critical behavior on the particle-hole symmetry. Our main result is that, for sufficiently strong disorder, the Mott-Anderson transition is characterized by a precisely defined two-fluid behavior, in which only a fraction of the electrons undergo a “site selective” Mott localization; the rest become Anderson-localized quasiparticles.

Aguiar, M. C. O.; Dobrosavljevi?, V.; Abrahams, E.; Kotliar, G.

2009-04-01

99

Critical behavior at the mott-anderson transition: a typical-medium theory perspective.  

PubMed

We present a detailed analysis of the critical behavior close to the Mott-Anderson transition. Our findings are based on a combination of numerical and analytical results obtained within the framework of typical-medium theory-the simplest extension of dynamical mean field theory capable of incorporating Anderson localization effects. By making use of previous scaling studies of Anderson impurity models close to the metal-insulator transition, we solve this problem analytically and reveal the dependence of the critical behavior on the particle-hole symmetry. Our main result is that, for sufficiently strong disorder, the Mott-Anderson transition is characterized by a precisely defined two-fluid behavior, in which only a fraction of the electrons undergo a "site selective" Mott localization; the rest become Anderson-localized quasiparticles. PMID:19518658

Aguiar, M C O; Dobrosavljevi?, V; Abrahams, E; Kotliar, G

2009-04-16

100

Evaluation of nuclear excitation by electronic transition in {sup 235}U plasma at local thermodynamic equilibrium  

SciTech Connect

A complete calculation of the nuclear excitation by electronic transition (NEET) rate of the first excited state of {sup 235}U in a local thermodynamic equilibrium (LTE) plasma is presented. The microscopic dynamics of the NEET probability are described allowing a clear description of the coupling between the atomic and nuclear transitions for the NEET effect. The atomic properties are estimated in the framework of a relativistic average-atom model. The statistical nature of the electronic transition spectrum is described by the mean of a Gaussian distribution around the average-atom configuration. The analysis of characteristic times occurring in the NEET probability allows one to calculate an equivalent excitation rate in a LTE {sup 235}U plasma. In the density-temperature plane, the NEET rate is strongly structured, showing the most relevant hydrodynamic conditions for the NEET process. The number of {sup 235}U nuclei, excited up to the 76.8 eV isomeric level in a high-intensity laser shot, has also been estimated.

Morel, P.; Meot, V.; Gosselin, G.; Gogny, D.; Younes, W. [Commissariat a l'Energie Atomique, Service de Physique Nucleaire, Boite Postale 12, 91680 Bruyeres-le-Chatel (France); Lawrence Livermore National Laboratory, Livermore, California 94551 (United States)

2004-06-01

101

Second-harmonic generation in lithium niobate nanowires for local fluorescence excitation.  

PubMed

We study the nonlinear optical properties of lithium niobate (LiNbO3) nanowires (NWs) fabricated by a top-down ion beam enhanced etching method. First, we demonstrate generation and propagation of the second-harmonic (SH) light in LiNbO3 NWs of typical rectangular cross-sections of 400 x 600 nm2 and length from 10 to 50 ?m. Then, we show local fluorescent excitation of 4',6-diamidino-2-phenylindole (DAPI) dye with the propagated SH signal in standard concentrations as for biological applications. By measuring the detected average power of the propagated fundamental harmonic (FH) and the SH signal at the output of the NWs, we directly prove the dominating role of the SH signal over possible two-photon excitation processes with the FH in the DAPI dye. We estimate that 63 ± 6 pW of the propagated SH average power is required for detectable dye excitation. Finally, we model the waveguiding of the SH light to determine the smallest NW cross-section (around 40x60 nm2) which is potentially able to excite fluorescence with a FH intensity below the cell damage threshold. PMID:23938816

Sergeyev, Anton; Geiss, Reinhard; Solntsev, Alexander S; Steinbrück, Andrea; Schrempel, Frank; Kley, Ernst-Bernhard; Pertsch, Thomas; Grange, Rachel

2013-08-12

102

A local normal description of vibrational excitations of pyramidal molecules in terms of Morse oscillators  

NASA Astrophysics Data System (ADS)

A general description of vibrational excitations of pyramidal molecules in both local and normal representations is presented. This study is restricted to the case when no tunneling motion is allowed. The Hamiltonian is first written in terms of curvilinear internal coordinates. The Wilson’s G matrix as well as the potential are expanded in terms of Morse variables, which allows the identification of a set of six Morse oscillators as zeroth-order Hamiltonian. An algebraic realization of the Hamiltonian is obtained by introducing a linear expansion of the coordinates and momenta in terms of creation and annihilation operators of Morse functions. This algebraic realization provides in natural form the representation of the Hamiltonian in terms of local interactions. The normal interactions are constructed by successive couplings of tensors defined as linear combinations of the ladder operators. The matrix transformation between the local and normal interactions is obtained for the complete Hamiltonian. This analysis provides the spectroscopic parameters in both local and normal schemes in explicit form as functions of the force constants and structure parameters. To exemplify, the analysis of the vibrational excitations of stibine and arsine is presented. Force constants as well as the corresponding x,K relations are given. A comparison with the results obtained using the U(?+1) unitary group approach is included.

Sánchez-Castellanos, M.; Amezcua-Eccius, C. A.; Álvarez-Bajo, O.; Lemus, R.

2008-02-01

103

Modeling of ion-acoustic soliton excitation through decay process of a localized perturbation  

SciTech Connect

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.

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

104

Controlled propagation of locally excited vortex dynamics in linear nanomagnet arrays  

NASA Astrophysics Data System (ADS)

The ability to propagate local electromagnetic excitation in a medium with spatially modulated physical properties is important for fundamental science and also for applications in photonic, phononic and magnonic crystals. Here, we present a controlled propagation of locally excited magnetic vortex dynamics through a linear array of nanomagnetic discs by controlling the polarization, chirality and shape of the discs. The control is based upon the magnetostatic interaction between the nanodiscs, mediated by the magnetic side charges generated by the gyrating vortices. The magnitude and sign of the side charges and their separation depend strongly on the magnetic ground states of the vortices, including the core polarization and the chirality. We find that the transmission of peak amplitude and velocity of propagation of the excitation along the array is optimized for identical core polarization and chirality of the nanodiscs with geometric asymmetry. More than seven times increase in the transmitted amplitude is observed in the optimized structure as opposed to the non-optimized structure, which is also found to be robust to defects.

Barman, Saswati; Barman, Anjan; Otani, Y.

2010-08-01

105

Spatial organization of vegetation arising from non-local excitation with local inhibition in forests  

NASA Astrophysics Data System (ADS)

Pattern formation in the biogeosciences is not limited to consideration of granular and fluid phenomena, but also occurs due to interactions within ecological systems. Here we present a novel mechanism of non-local activation and local inhibition that arises in the dynamics of competition and predation associated with parent trees and their seedlings. These dynamics, known as the Janzen-Connell (JC) effect, arise when recruitment and growth of seedlings is positively correlated to the distance from the parent tree. Such effects generate highly organized vegetation biomass spatial patterns when coupled to a revised Fisher-Kolmogorov (FK) equation. Over a single generation, the revised FK model calculations predict a "hen and chicks" dynamic pattern with mature trees surrounded by new seedlings growing at characteristic spatial distances in agreement with field data. Over longer timescales, the importance of stochastic dynamics, such as those associated with randomly occurring light gaps, increase thereby causing a substantial deviation between predictions from the deterministic FK model and its stochastic counterpart derived to account for such random disturbances. At still longer timescales, however, statistical measures of the spatial organization, specifically the spatial density of mature trees and their minimum spacing, converge between the two model representations.

Thompson, S. E.; Katul, G. G.; Terborgh, J.; Alvarez-Loayza, P.

2009-12-01

106

Critical excitation spectrum of a quantum chain with a local three-spin coupling  

SciTech Connect

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{sub 4},A{sub 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.

McCabe, John F.; Wydro, Tomasz [2331 Gales Court, Scotch Plains, New Jersey 07076 (United States); Statistical Physics Group, P2M Department, Institut Jean Lamour Nancy Universite, Universite Paul Verlaine - Metz BP 70239, F-54506 Vandoeuvre-les-Nancy Cedex (France)

2011-09-15

107

Exact superconducting ground states of the extended Anderson model  

NASA Astrophysics Data System (ADS)

We obtain exact ground states of an extended periodic Anderson model (EPAM) with non-local hybridization and Coulomb repulsion between f and c electrons (Falicov-Kimball term) in one dimension. We show that for a range of parameter values these ground states exhibit composite hole pairing and superconductivity that originate from purely electronic interactions.

Sarasua, L. G.

2011-10-01

108

Testing the Order Parameter of the Anderson Transition  

NASA Astrophysics Data System (ADS)

The typical value of the local density of states ?typ, known as a candidate of the order parameter of the Anderson transition, of two-dimensional disordered electron systems with spin--orbit interactions is studied for assessing the validity of ?typ as the order parameter. We show that ?typ behaves critically as ?typ\\propto (Ec-E)? with ?=0.466± 0.095 near the transition point. It is also found that the exponent ? satisfies the scaling relation with the Lipschitz--Hölder exponent ?0. Furthermore, we demonstrate that fluctuations in ?typ at the Anderson transition obey the generalized Gumbel distribution, which is expected to be the universal distribution function of critical fluctuations of order parameters. These results suggest that ?typ is a suitable quantity of the order parameter of the Anderson transition.

Yakubo, Kousuke; Mizutaka, Shogo

2012-10-01

109

The Anderson Quin Cycle. Final report  

Microsoft Academic Search

The objective of this study was to make a more refined evaluation of the Anderson Quin Cycle based on most recent information on the performance of various elements that will be used in the Anderson Quin Cycle. My original estimate of the work plan for evaluating and optimizing the Anderson Quin Cycle called for 7000 man hours of work. Since

J. H. Anderson; W. M. Bilbow

1993-01-01

110

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

PubMed Central

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.

2010-01-01

111

Core localization and {sigma}* delocalization in the O 1s core-excited sulfur dioxide molecule  

SciTech Connect

Electron-ion-ion coincidence measurements of sulfur dioxide at discrete resonances near the O 1s ionization edge are reported. The spectra are analyzed using a model based upon molecular symmetry and on the geometry of the molecule. We find clear evidence for molecular alignment that can be ascribed to symmetry properties of the ground and core-excited states. Configuration interaction (CI) calculations indicate geometry changes in accord with the measured spectra. For the SO{sub 2} molecule, however, we find that the localized core hole does not produce measurable evidence for valence localization, since the transition dipole moment is not parallel to a breaking {sigma}* O-S bond, in contrast to the case of ozone. The dissociation behavior based upon the CI calculations using symmetry-broken orbitals while fixing a localized core-hole site is found to be nearly equivalent to that using symmetry-adapted orbitals. This implies that the core-localization effect is not strong enough to localize the {sigma}* valence orbital.

Lindgren, Andreas; Kivimaeki, Antti; Sorensen, Stacey L. [Department of Synchrotron Radiation Research, Institute of Physics, University of Lund, S-221 00 Lund (Sweden); Kosugi, Nobuhiro [UVSOR, Institute for Molecular Science (IMS), Myodaiji, Okazaki 444-8585 (Japan); Gisselbrecht, Mathieu [MAX-Lab, Box 118, University of Lund, S-221 00 Lund (Sweden); Burmeister, Florian [Department of Physics, Uppsala University, Box 530, S-751 21 Uppsala (Sweden); Naves de Brito, Arnaldo [Laboratorio Nacional de Luz Sincrotron (LNLS), Box 6192, 13084-971 Campinas SP (Brazil)

2008-03-21

112

Local electron beam excitation and substrate effect on the plasmonic response of single gold nanostars.  

PubMed

We performed cathodoluminescence (CL) spectroscopy and imaging in a high-resolution scanning electron microscope to locally and selectively excite and investigate the plasmonic properties of a multi-branched gold nanostar on a silicon substrate. This method allows us to map the local density of optical states from the nanostar with a spatial resolution down to a few nanometers. We resolve, both in the spatial and spectral domain, different plasmon modes associated with the nanostar. Finite-difference time-domain (FDTD) numerical simulations are performed to support the experimental observations. We investigate the effect of the substrate on the plasmonic properties of these complex-shaped nanostars. The powerful CL-FDTD combination helps us to understand the effect of the substrate on the plasmonic response of branched nanoparticles. PMID:24029251

Das, Pabitra; Kedia, Abhitosh; Kumar, Pandian Senthil; Large, Nicolas; Chini, Tapas Kumar

2013-09-12

113

Local electron beam excitation and substrate effect on the plasmonic response of single gold nanostars  

NASA Astrophysics Data System (ADS)

We performed cathodoluminescence (CL) spectroscopy and imaging in a high-resolution scanning electron microscope to locally and selectively excite and investigate the plasmonic properties of a multi-branched gold nanostar on a silicon substrate. This method allows us to map the local density of optical states from the nanostar with a spatial resolution down to a few nanometers. We resolve, both in the spatial and spectral domain, different plasmon modes associated with the nanostar. Finite-difference time-domain (FDTD) numerical simulations are performed to support the experimental observations. We investigate the effect of the substrate on the plasmonic properties of these complex-shaped nanostars. The powerful CL-FDTD combination helps us to understand the effect of the substrate on the plasmonic response of branched nanoparticles.

Das, Pabitra; Kedia, Abhitosh; Senthil Kumar, Pandian; Large, Nicolas; Chini, Tapas Kumar

2013-10-01

114

Not by spikes alone: responses of coordinating neurons and the swimmeret system to local differences in excitation.  

PubMed

Swimmeret coordinating neurons in the crayfish CNS collectively encode a detailed cycle-by-cycle report on features of the motor output to each swimmeret. This information coordinates the motor output that drives swimmeret movements. To see how coordinating neurons responded to forced changes in intersegmental phase, we used a split-bath, repeated-measures experimental design to expose different regions of isolated abdominal nerve cords to different levels of excitation. We present a quantitative description of the firing of power-stroke (PS) motor units and two kinds of coordinating interneurons, ASC(E) and DSC, recorded simultaneously from each swimmeret ganglion under uniform and nonuniform excitation. When anterior and posterior ganglia were excited differently, several parameters of the swimmeret motor pattern were affected. Strengths of PS bursts in each ganglion were determined by local excitation. The phase of PS bursts in neighboring ganglia changed at the excitation boundary. Coordinating neurons from the two ganglia closest to the excitation boundary were most affected by nonuniform excitation. ASC(E) neurons tracked the timing and duration of each PS burst in their home ganglion, but did not follow changes in PS burst strength. DSC neurons changed the duration, phase, and number of spikes per burst. We propose two models to explain these results. First, the period expressed under nonuniform conditions is the sum of local intersegmental latencies and these latencies are determined by local excitation. Second, the phase change at the excitation boundary is determined by local modulation of the targets of the intersegmental coordinating neurons, not by modulation of the coordinating neurons themselves. PMID:17050832

Mulloney, Brian; Hall, Wendy M

2006-10-18

115

Natural triple excitations in local coupled cluster calculations with pair natural orbitals  

NASA Astrophysics Data System (ADS)

In this work, the extension of the previously developed domain based local pair-natural orbital (DLPNO) based singles- and doubles coupled cluster (DLPNO-CCSD) method to perturbatively include connected triple excitations is reported. The development is based on the concept of triples-natural orbitals that span the joint space of the three pair natural orbital (PNO) spaces of the three electron pairs that are involved in the calculation of a given triple-excitation contribution. The truncation error is very smooth and can be significantly reduced through extrapolation to the zero threshold. However, the extrapolation procedure does not improve relative energies. The overall computational effort of the method is asymptotically linear with the system size O(N). Actual linear scaling has been confirmed in test calculations on alkane chains. The accuracy of the DLPNO-CCSD(T) approximation relative to semicanonical CCSD(T0) is comparable to the previously developed DLPNO-CCSD method relative to canonical CCSD. Relative energies are predicted with an average error of approximately 0.5 kcal/mol for a challenging test set of medium sized organic molecules. The triples correction typically adds 30%-50% to the overall computation time. Thus, very large systems can be treated on the basis of the current implementation. In addition to the linear C150H302 (452 atoms, >8800 basis functions) we demonstrate the first CCSD(T) level calculation on an entire protein, Crambin with 644 atoms, and more than 6400 basis functions.

Riplinger, Christoph; Sandhoefer, Barbara; Hansen, Andreas; Neese, Frank

2013-10-01

116

Beam-shape Coefficients, Localization Principle and Excitation of Resonances in Mie's Scattering  

NASA Astrophysics Data System (ADS)

Exact and distance-independent expressions for beam-shape coefficients (BSC's) in various cases are obtained. For a weakly focused beam in the two-dimensional (three-dimensional) case, the expression is shown equal (linearly related) to the value of the beam field at the distance of m/k ( ll+1 /k) from the origin, where m( l) is the azimuthal (principal) angular momentum number and k is the wavenumber. This provides a rigorous foundation for and a better understanding of the localization principle of van de Hulst. Furthermore, it gives corrections to the principle if the beam is more focused. With the knowledge of the asymptotic behavior of the positions and widths (or quality value) for the morphology-dependent resonances (MDR's) in Mie's scattering, the results are applied to discuss and answer questions regarding the excitation of high-Q MDR's by good collimated wave beams focused at positions essentially off the surface of the sphere.

Fu, Pengpeng

117

Attraction of spiral waves by localized inhomogeneities with small-world connections in excitable media.  

PubMed

Trapping and untrapping of spiral tips in a two-dimensional homogeneous excitable medium with local small-world connections are studied by numerical simulation. In a homogeneous medium which can be simulated with a lattice of regular neighborhood connections, the spiral wave is in the meandering regime. When changing the topology of a small region from regular connections to small-world connections, the tip of the spiral waves is attracted by the small-world region, where the average path length declines with the introduction of long distant connections. The "trapped" phenomenon also occurs in regular lattices where the diffusion coefficient of the small region is increased. The above results can be explained by the eikonal equation, the Luther equation, and the relation between the core radius and the diffusion coefficient. PMID:15244920

Wang, Xiaonan; Lu, Ying; Jiang, Minxi; Ouyang, Qi

2004-05-27

118

Localized spin-wave excitation by the evanescent microwave scanning probe  

SciTech Connect

We report a technique for the local contactless spin-wave excitation using the evanescent microwave scanning probe. Our probe is based on a dielectric resonator with the thin slit aperture. It operates at 8.8 GHz, has a spatial resolution of 10-100 {mu}m, and may be operated in the parallel and in the perpendicular magnetic field. The measurements can be performed in contact mode or by scanning the sample at constant probe-sample separation. Using 120-150 nm thick Permalloy films on a glass substrate as test samples, we show how our technique can be used for thickness measurements of thin magnetic films and for the mapping of their magnetic properties, such as magnetization and surface anisotropy.

Sakran, F.; Golosovsky, M.; Davidov, D.; Monod, P. [Racah Institute of Physics, The Hebrew University of Jerusalem, Jerusalem 91904 (Israel); ESPCI, 10 rue Vauquelin, 75231 Paris Cedex 05 (France)

2006-02-15

119

Probing Dynamically Tunable Localized Surface Plasmon Resonances of Film-Coupled Nanoparticles by Evanescent Wave Excitation  

PubMed Central

The localized surface plasmon resonance (LSPR) spectrum associated with a gold nanoparticle (NP) coupled to a gold film exhibits extreme sensitivity to the nano-gap region where the fields are tightly localized. The LSPR of an ensemble of film-coupled NPs can be observed using an illumination scheme similar to that used to excite the surface plasmon resonance (SPR) of a thin metallic film; however, in the present system, the light is used to probe the highly sensitive distance-dependent LSPR of the gaps between NPs and film rather than the delocalized SPR of the film. We show that the SPR and LSPR spectral contributions can be readily distinguished, and we compare the sensitivities of both modes to displacements in the average gap between a collection of NPs and the gold film. The distance by which the NPs are suspended in solution above the gold film is fixed via a thin molecular spacer layer, and can be further modulated by subjecting the NPs to a quasistatic electric field. The observed LSPR spectral shifts triggered by the applied voltage can be correlated with Angstrom scale displacements of the NPs, suggesting the potential for chip-scale or flow-cell plasmonic nanoruler devices with extreme sensitivity.

Mock, Jack J.; Hill, Ryan T.; Tsai, Yu-Ju; Chilkoti, Ashutosh; Smith, David R.

2012-01-01

120

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

SciTech Connect

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.

Volkov, S. N.; Kaplan, A. E. [Department of Electrical and Computer Engineering, Johns Hopkins University, Baltimore, Maryland 21218 (United States)

2010-04-15

121

Spectral diffusion of single molecule fluorescence: A probe of low-frequency localized excitations in disordered crystals  

NASA Astrophysics Data System (ADS)

Spectral diffusion of the transition frequency of single pentacene molecules in p-terphenyl crystal was recently observed experimentally. In this Letter we propose a microscopic theoretical model to explain this phenomenon. Analysis of the experimental data with our model yields detailed microscopic information about the nature and spatial distribution of the localized excitations responsible for the observed spectral diffusion.

Reilly, Philip D.; Skinner, J. L.

1993-12-01

122

2. ANDERSON STREET SCHOOL, 1300 BLOCK BULL STREET, NORTH ELEVATION ...  

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

2. ANDERSON STREET SCHOOL, 1300 BLOCK BULL STREET, NORTH ELEVATION - Savannah Victorian Historic District, Bounded by Gwinnett, East Broad, West Broad Street & Anderson Lane, Savannah, Chatham County, GA

123

5. ANDERSON STREET SCHOOL, 1300 BLOCK BULL STREET, ENTRANCE GATE ...  

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

5. ANDERSON STREET SCHOOL, 1300 BLOCK BULL STREET, ENTRANCE GATE - Savannah Victorian Historic District, Bounded by Gwinnett, East Broad, West Broad Street & Anderson Lane, Savannah, Chatham County, GA

124

Local CC2 response method based on the Laplace transform: Orbital-relaxed first-order properties for excited states  

NASA Astrophysics Data System (ADS)

A multistate local CC2 response method for the calculation of orbital-relaxed first order properties is presented for ground and electronically excited states. It enables the treatment of excited state properties including orbital relaxation for extended molecular systems and is a major step on the way towards analytic gradients with respect to nuclear displacements. The Laplace transform method is employed to partition the eigenvalue problem and the lambda equations, i.e., the doubles parts of these equations are inverted on-the-fly, leaving only the corresponding effective singles equations to be solved iteratively. Furthermore, the state specific local approximations are adaptive. Density-fitting is utilized to decompose the electron-repulsion integrals. The accuracy of the local approximation is tested and the efficiency of the new code is demonstrated on the example of an organic sensitizer for solar-cell applications, which consists of about 100 atoms.

Ledermüller, Katrin; Kats, Daniel; Schütz, Martin

2013-08-01

125

Local CC2 response method based on the Laplace transform: orbital-relaxed first-order properties for excited states.  

PubMed

A multistate local CC2 response method for the calculation of orbital-relaxed first order properties is presented for ground and electronically excited states. It enables the treatment of excited state properties including orbital relaxation for extended molecular systems and is a major step on the way towards analytic gradients with respect to nuclear displacements. The Laplace transform method is employed to partition the eigenvalue problem and the lambda equations, i.e., the doubles parts of these equations are inverted on-the-fly, leaving only the corresponding effective singles equations to be solved iteratively. Furthermore, the state specific local approximations are adaptive. Density-fitting is utilized to decompose the electron-repulsion integrals. The accuracy of the local approximation is tested and the efficiency of the new code is demonstrated on the example of an organic sensitizer for solar-cell applications, which consists of about 100 atoms. PMID:24006978

Ledermüller, Katrin; Kats, Daniel; Schütz, Martin

2013-08-28

126

Local CC2 response method for triplet states based on Laplace transform: excitation energies and first-order properties.  

PubMed

A new multistate local CC2 response method for calculating excitation energies and first-order properties of excited triplet states in extended molecular systems is presented. The Laplace transform technique is employed to partition the left/right local CC2 eigenvalue problems as well as the linear equations determining the Lagrange multipliers needed for the properties. The doubles part in the equations can then be inverted on-the-fly and only effective equations for the singles part must be solved iteratively. The local approximation presented here is adaptive and state-specific. The density-fitting method is utilized to approximate the electron-repulsion integrals. The accuracy of the new method is tested by comparison to canonical reference values for a set of 12 test molecules and 62 excited triplet states. As an illustrative application example, the lowest four triplet states of 3-(5-(5-(4-(bis(4-(hexyloxy)phenyl)amino)phenyl)thiophene-2-yl)thiophene-2-yl)-2-cyanoacrylic acid, an organic sensitizer for solar-cell applications, are computed in the present work. No triplet charge-transfer states are detected among these states. This situation contrasts with the singlet states of this molecule, where the lowest singlet state has been recently found to correspond to an excited state with a pronounced charge-transfer character having a large transition strength. PMID:21197979

Freundorfer, Katrin; Kats, Daniel; Korona, Tatiana; Schütz, Martin

2010-12-28

127

Localized electron dynamics in attosecond-pulse-excited molecular systems: Probing the time-dependent electron density by sudden photoionization  

NASA Astrophysics Data System (ADS)

Ultrafast UV excitation can prepare a nonstationary coherent superposition of molecular electronic states. The purely electronic dynamics before the onset of nuclear motion can be probed by a sudden XUV ionization of the electronic wave packet. Dynamical computations at the many-electron level on the LiH and 1-azabicyclo[3.3.3]undecane (C10H19N) molecules show that molecular frame photoelectron angular distributions reflect the spatial localization and undulations of the electronic coherent superposition accessed by the initial ultrafast UV excitation. The sudden ionization is sensitive to interference effects.

Mignolet, B.; Levine, R. D.; Remacle, F.

2012-11-01

128

Low energy properties of the two-impurity Anderson model  

NASA Astrophysics Data System (ADS)

We investigate the low energy properties of the two-impurity Anderson model with the complete-Fock-space numerical renormalization group method. From the calculated spectral function, correlation functions and self-energy, two energy scales are identified, as onsets of the Kondo resonance and the Fermi liquid behaviors. With the tuning of the RKKY interaction, the latter is uniformly suppressed to zero in the particle-hole symmetric case, resembling the Jones-Varma quantum critical point. In cases with the particle-hole asymmetry, an inter-impurity hybridization term is generated, which turns the quantum critical point into a crossover. Similar behaviors are found with either a direct hopping term or a local magnetic field, to lift the parity or spin degeneracies, respectively. Application to the Anderson lattice model is also presented.

Zhu, Lijun; Zhu, Jian-Xin

2010-03-01

129

Phase-space signatures of the Anderson transition  

NASA Astrophysics Data System (ADS)

We use the inverse participation ratio based on the Husimi function to perform a phase-space analysis of the Anderson model in one, two, and three dimensions. Important features of the quantum states remain observable in phase space in the large system size limit, while they would be lost in a real- or momentum-space description. From perturbative approaches in the limits of weak and strong disorder, we find that the appearance of a delocalization-localization transition is connected to the coupling, by a weak potential, of momentum eigenstates which are far apart in momentum space. While this is fully consistent with the known dependence of the existence of the Anderson transition on dimensionality, the resulting criterion can be applied to other models as well. The phase-space approach thus sheds new light on the metal-insulator transition.

Wobst, André; Ingold, Gert-Ludwig; Hänggi, Peter; Weinmann, Dietmar

2003-08-01

130

A characterization of the Anderson metal-insulator transport transition  

Microsoft Academic Search

We investigate the Anderson metal-insulator transition for random\\u000aSchrödinger operators. We define the strong insulator\\u000aregion to be the part of the spectrum where the random operator\\u000aexhibits strong dynamical localization in the Hilbert-Schmidt\\u000anorm. We introduce a local transport exponent ?(E) and set\\u000athe weak metallic transport region to be the part of the\\u000aspectrum with nontrivial transport (i.e.,

François Germinet; Abel Klein

131

Ultrahigh-field MRI whole-slice and localized RF field excitations using the same RF transmit array.  

PubMed

In this paper, a multiport driving mechanism is numerically implemented at ultra high-field (UHF) magnetic resonance imaging (MRI) to provide 1) homogenous whole-slice (axial, sagittal, or coronal) and 2) highly localized radio frequency (RF) field excitation within the same slices, all with the same RF transmit array (here chosen to be a standard transverse electromagnetic (TEM) resonator/coil). The method is numerically tested using a full-wave model of a TEM coil loaded with a high-resolution/18-tissue/anatomically detailed human head mesh. The proposed approach is solely based on electromagnetic and phased array antenna theories. The results demonstrate that both homogenous whole-slice as well as localized RF excitation can be achieved within any slice of the head at 7 T (298 MHz for proton imaging). PMID:17024837

Ibrahim, Tamer S

2006-10-01

132

Non-local effects in spatial distribution of excitation rates in positive column of glow discharge plasma of molecular gases  

NASA Astrophysics Data System (ADS)

At simulations of gas-discharge plasmas the electron distribution function (EDF) is usually calculated using a local approximation (LA) which is applicable only when electron energy relaxation length le < R -- plasma size. For atomic gases le > 100l (l -- electron free-path-length), so the LA for EDF is not valid up to high pressures. By contrast, in molecular gases due to strong vibrational excitation with low energy threshold, the length le is small le˜l. And so it is assumed everywhere that the LA for EDF calculation in molecular gases is valid in any cases when diffusive approximation R > l is applicable. In this report it is shown that in molecular gases local approximation is inapplicable on the discharge periphery, where ambipolar field exceeds longitudinal field. A heating of fast electrons in ambipolar field gives rise to excitation constants from centre to periphery of discharge.

Kudryavtsev, Anatoly; Bogdanov, Eugene; Tsendin, Lev

2008-10-01

133

Local and nonlocal parametric excitation of GAMs by finite beta drift waves  

NASA Astrophysics Data System (ADS)

The geodesic acoustic modes (GAMs) can be excited in the edge region of toroidal plasmas by mode coupling to primary modes like the drift waves. We will present mode coupling analysis of the excitation of GAMs by finite beta drift waves. The finite beta effects stabilize the excitation of GAMs. The nonlocal study of the excitation of these modes leads to a complex eigenmode equation which yield bounded solutions on the edge density and temperature pedestals. The solutions show a two scale structure in which the fast scale is dictated by the three-wave frequency resonance condition, while the slow scale is determined by the combination of the edge density and/or temperature scales as well as the ion larmor radius.

Guzdar, Parvez; Kleva, Robert; Chakrabarti, Nikhil; Kaw, Predhiman; Naulin, Volker; Rasmussen, Jens

2008-11-01

134

Nonlocal and local magnetization dynamics excited by an RF magnetic field in magnetic multilayers  

NASA Astrophysics Data System (ADS)

A microwave study in spintronic devices has been actively pursued in the past several years due to the fertile physics and potential applications. On one hand, a passive use of microwave can be very helpful to analyze and understand the magnetization dynamics in spintronic devices. Examples include ferromagnetic resonance (FMR) measurements, and various microwave spectrum analyses in ferromagnetic materials. The most important chrematistic parameter for the phenomenological analysis on the magnetization dynamics is, so called, the Gilbert damping constant. In this work, a relatively new measurement technique, a flip-chip FMR measurement, to conduct the ferromagnetic resonance measurements has been developed. The measurement technique is equally comparable to a conventional FMR measurement. The Gilbert damping constants were extracted for single ferromagnetic layer, spin vale structures, and magnetic tunnel junctions (MTJs). On the other hand, an active use of microwave yields a great potential for interesting phenomena which give new functionalities into spintronic devices. For instance, a spin wave excitation by an rf field can be used to reduce the switching field of a ferromagnet, i.e. microwave assisted magnetization reversal, which could be a potential application in advanced recording media. More interestingly, a precessing magnetization driven by an rf field can generate a pure spin current into a neighboring layer, i.e. spin pumping effect, which is one of the candidates for generating a pure spin current. A ferromagnetic tunnel junction (MTJ) is one of the important devices in spintronics, which is also the key device to investigate the local and nonlocal magnetization dynamics in this work. Therefore, it is also important to develop high quality MTJs. My work starts from the development of MTJ with AlOx and MgO tunnel barriers where it was found it is crucial to find the proper condition for forming a few nanometers thick tunnel barrier. After obtaining quality MTJs, we proceeded to the study on magnetization dynamics using the MTJs. First interesting phenomenon found in this work is the microwave assisted magnetization reversal (MAMR). It is found that magnetization reversal can be achieved efficiently by an appropriate power and frequency microwave. Moreover, there is a mutual relationship between microwave power and frequency for achieving a maximum switching field reduction. This effect can be very useful in magnetic data storage device which essentially needs to reduce the "effective" coercivity field. In the study of nonlocal magnetization dynamics, we tried to detect the spin accumulation induced by spin pumping effect in FM/NM/I/FM, FM/I/NM and FM/I/FM structures with a microwave excitation (FM: ferromagnetic material, NM: nonmagnetic material, and I: tunnel barrier). Interestingly, in the FM/I/NM and FM/I/FM structures, we observed ˜muV dc voltage due to the precessing magnetizations. It is found that the dc voltage we observed is much larger than the current the spin pumping theory predicts. Therefore we speculated a new mechanism to explain the results. Although we discussed only a portion of the magnetization dynamics involving nonlinear and nonequilibrium phenomena, it reveals that there is still a fertile physics which has not yet been investigated or explained.

Moriyama, Takahiro

135

Two-dimensional Anderson-Hubbard model in the DMFT + {Sigma} approximation  

SciTech Connect

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.

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

136

The Dystrophin-associated Protein Complex Maintains Muscle Excitability by Regulating Ca2+-dependent K+ (BK) Channel Localization*  

PubMed Central

The dystrophin-associated protein complex (DAPC) consists of several transmembrane and intracellular scaffolding elements that have been implicated in maintaining the structure and morphology of the vertebrate neuromuscular junction (NMJ). Genetic linkage analysis has identified loss-of-function mutations in DAPC genes that give rise to degenerative muscular dystrophies. Although much is known about the involvement of the DAPC in maintaining muscle integrity, less is known about the precise contribution of the DAPC in cell signaling events. To better characterize the functional role of the DAPC at the NMJ, we used electrophysiology, immunohistochemistry, and fluorescent labeling to directly assess cholinergic synaptic transmission, ion channel localization, and muscle excitability in loss-of-function (lf) mutants of Caenorhabditis elegans DAPC homologues. We found that all DAPC mutants consistently display mislocalization of the Ca2+-gated K+ channel, SLO-1, in muscle cells, while ionotropic acetylcholine receptor (AChR) expression and localization at the NMJ remained unaltered. Synaptic cholinergic signaling was also not significantly impacted across DAPC(lf) mutants. Consistent with these findings and the postsynaptic mislocalization of SLO-1, we observed an increase in muscle excitability downstream of cholinergic signaling. Based on our results, we conclude that the DAPC is not involved in regulating AChR architecture at the NMJ, but rather functions to control muscle excitability, in an activity-dependent manner, through the proper localization of SLO-1 channels.

Sancar, Feyza; Touroutine, Denis; Gao, Shangbang; Oh, Hyun J.; Gendrel, Marie; Bessereau, Jean-Louis; Kim, Hongkyun; Zhen, Mei; Richmond, Janet E.

2011-01-01

137

It's All About the Journey: Walter Anderson  

Microsoft Academic Search

There once was a man who risked everything to bring himself and nature into one thing called art. Go behind the scenes on the journey of The Secret World of Walter Anderson to see how author Hester Bass and illustrator E.B. Lewis collaborated on this award-winning biography of Mississippi’s own Walter Anderson. The exhibition, based on the book featuring the

Hester Bass

2012-01-01

138

Flow visualization using fluorescence from locally seeded I2 excited by an ArF excimer laser  

NASA Astrophysics Data System (ADS)

A new concept for flow visualization is demonstrated in which fluorescence from locally seeded iodine is viewed in the wake of simple aerodynamic models at Mach 6. Localized seeding is performed by painting a small area of a ceramic model with a tincture of iodine. When the model is injected into the flow, the adsorbed iodine is entrained into the boundary layer, follows the model contour, and ultimately mixes into the wake region. Planar ``snapshots'' of the wake flow are taken by exciting the iodine with an ArF excimer laser sheet at 193 nm and observing the fluorescence in the 210-600 nm region with an intensified CCD camera.

Exton, R. J.; Balla, R. J.; Shirinzadeh, B.; Hillard, M. E.; Brauckmann, G. J.

139

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

PubMed Central

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.

Sodt, Alex J.; Ratner, Mark A.

2010-01-01

140

Excitation of dark plasmons in metal nanoparticles by a localized emitter.  

SciTech Connect

We study theoretically a dipole emitter placed near a metal nanoparticle and near small chains of two and three nanoparticles. The emitter can efficiently excite dark, or nonradiative, surface-plasmon modes in the nanostructures, in addition to the well-known bright modes. In the case of coupled nanoparticles, the origins of the bright and dark modes can be understood in the context of plasmon hybridization. Excitation of dark modes in nanoparticle chains allows for subwavelength guiding of optical energy with no radiative losses and thus with improved propagation lengths.

Liu, M.; Lee, T.-W.; Gray, S.; Guyot-Sionnest, P.; Pelton, M.; Univ. of Chicago

2009-03-13

141

The fate of optical excitations in small polyhedral ZnS clusters: a theoretical study of the excitation and localization of electrons in Zn4S4 and Zn6S6.  

PubMed

We explore the excited state energy landscape of small polyhedral zinc sulfide clusters (Zn(4)S(4) and Zn(6)S(6)) using time-dependent density functional theory and correlated wave function based methods. We predict the optical absorption and photoluminescence spectra of the polyhedral clusters and demonstrate that, upon relaxation of the excited state, these nanostructures break symmetry and an electron and a hole localize on a small number of Zn (electron) and S (hole) centers. We further test several exchange-correlation potentials for their ability to recover the correlated wave function description of the excited state. Finally, we discuss how the degeneracy of excited states in nanostructures, such as those considered here, results in a Jahn-Teller distortion of the excited state geometry, and how numerical problems arising from this can be circumvented by starting the optimization of excited states from structures distorted along the ground state vibrational normal modes. PMID:21322709

Zwijnenburg, Martijn A; Sousa, Carmen; Illas, Francesc; Bromley, Stefan T

2011-02-14

142

Non-stationary excitation of two localized spin-wave modes in a nano-contact spin torque oscillator  

NASA Astrophysics Data System (ADS)

We measure and simulate micromagnetically a framework based upon a nano-contact spin torque oscillator where two distinct localized evanescent spin-wave modes can be detected. The resulting frequency spectrum is composed by two peaks, corresponding to the excited modes, which lie below the ferromagnetic resonance frequency, and a low-frequency tail, which we attribute to the non-stationary switching between these modes. By using Fourier, wavelet, and Hilbert-Huang transforms, we investigate the properties of these modes in time and spatial domains, together with their spatial distribution. The existence of an additional localized mode (which was neither predicted by theory nor by previous numerical and experimental findings) has to be attributed to the large influence of the current-induced Oersted field strength which, in the present setup, is of the same order of magnitude as the external field. As a further consequence, the excited spin-waves, contrarily to what usually assumed, do not possess cylindrical symmetry: the Oersted field induces these modes to be excited at the two opposite sides of the region beneath the nano-contact.

Consolo, G.; Finocchio, G.; Siracusano, G.; Bonetti, S.; Eklund, A.; A?kerman, J.; Azzerboni, B.

2013-10-01

143

Quantum phase transitions in a pseudogap Anderson-Holstein model  

NASA Astrophysics Data System (ADS)

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

Cheng, Mengxing; Ingersent, Kevin

2013-02-01

144

Periodic Anderson model with electron-phonon correlated conduction band  

NASA Astrophysics Data System (ADS)

This Rapid Communication reports dynamical mean-field calculations for the periodic Anderson model in which the conduction band is coupled to phonons. Motivated in part by recent attention to the role of phonons in the ?-? transition in Ce, this model yields a rich and unexpected phase diagram which is of intrinsic interest. Specifically, above a critical value of the electron-phonon interaction, a first-order transition with two coexisting phases develops in the temperature-hybridization plane, which terminates at a second-order critical point. The coexisting phases display the familiar Kondo screened and local-moment character, yet they also exhibit pronounced polaronic and bipolaronic properties, respectively.

Zhang, Peng; Reis, Peter; Tam, Ka-Ming; Jarrell, Mark; Moreno, Juana; Assaad, Fakher; McMahan, A. K.

2013-03-01

145

Photoelectron emission from island metallic sodium films during the excitation of localized plasmon resonances  

SciTech Connect

The photoelectron emission from island sodium films is studied under the action of radiation that is resonant to the collective electron excitations in the nanoparticles forming a film. Noticeable deviations from the Fowler law and an increase in the photoelectron yield are detected. The dependences of the photoeffect efficiency from these films on their structural parameters, the polarization vector, and the angle of radiation incidence are obtained.

Vartanyan, T. A.; Vashchenko, E. V., E-mail: vashenko.elena@mail.ru; Leonov, N. B.; Przhibel'skii, S. G.; Khromov, V. V. [St. Petersburg State University of Information Technologies, Mechanics, and Optics (Russian Federation)

2009-07-15

146

Reactive and internal contributions to the thermal conductivity of local thermodynamic equilibrium nitrogen plasma: The effect of electronically excited states  

SciTech Connect

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.

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

147

Nanoscale spin reversal by non-local angular momentum transfer following ultrafast laser excitation in ferrimagnetic GdFeCo  

NASA Astrophysics Data System (ADS)

Ultrafast laser techniques have revealed extraordinary spin dynamics in magnetic materials that equilibrium descriptions of magnetism cannot explain. Particularly important for future applications is understanding non-equilibrium spin dynamics following laser excitation on the nanoscale, yet the limited spatial resolution of optical laser techniques has impeded such nanoscale studies. Here we present ultrafast diffraction experiments with an X-ray laser that probes the nanoscale spin dynamics following optical laser excitation in the ferrimagnetic alloy GdFeCo, which exhibits macroscopic all-optical switching. Our study reveals that GdFeCo displays nanoscale chemical and magnetic inhomogeneities that affect the spin dynamics. In particular, we observe Gd spin reversal in Gd-rich nanoregions within the first picosecond driven by the non-local transfer of angular momentum from larger adjacent Fe-rich nanoregions. These results suggest that a magnetic material’s microstructure can be engineered to control transient laser-excited spins, potentially allowing faster (~ 1?ps) spin reversal than in present technologies.

Graves, C. E.; Reid, A. H.; Wang, T.; Wu, B.; de Jong, S.; Vahaplar, K.; Radu, I.; Bernstein, D. P.; Messerschmidt, M.; Müller, L.; Coffee, R.; Bionta, M.; Epp, S. W.; Hartmann, R.; Kimmel, N.; Hauser, G.; Hartmann, A.; Holl, P.; Gorke, H.; Mentink, J. H.; Tsukamoto, A.; Fognini, A.; Turner, J. J.; Schlotter, W. F.; Rolles, D.; Soltau, H.; Strüder, L.; Acremann, Y.; Kimel, A. V.; Kirilyuk, A.; Rasing, Th.; Stöhr, J.; Scherz, A. O.; Dürr, H. A.

2013-04-01

148

Dual effect of local anesthetics on the function of excitable rod outer segment disk membrane  

SciTech Connect

The effects of local anesthetics and a divalent cation, Ca2+, on the function of rhodopsin were estimated from the measurements of light-induced proton uptake. The light-induced proton uptake by rhodopsin in the rod outer segment disk membrane was enhanced at lower pH (4) but depressed at higher pHs (6 to 8) by the tertiary amine local anesthetics lidocaine, bupivacaine, tetracaine, and dibucaine. The order of local anesthetic-induced depression of the proton uptake followed that of their clinical anesthetic potencies. The depression of the proton uptake versus the concentration of the uncharged form of local anesthetic nearly describes the same curve for small and large dose of added anesthetic. Furthermore, a neutral local anesthetic, benzocaine, depressed the proton uptake at all pHs between 4 and 7. These results indicate that the depression of the proton uptake is due to the effect of only the uncharged form. It is hypothesized that the uncharged form of local anesthetics interacts hydrophobically with the rhodopsin in the disk membrane. The dual effect of local anesthetics on the proton uptake, on the other hand, suggests that the activation of the function of rhodopsin may be caused by the charged form. There was no significant change in the light-induced proton uptake by rhodopsin when 1 mM of Ca2+ was introduced into the disk membrane at varying pHs in the absence or presence of local anesthetics. This fact indicates that Ca2+ ion does not influence the diprotonating process of metarhodopsin; neither does it interfere with the local anesthetic-induced changes in the rhodopsin molecule.

Mashimo, T.; Abe, K.; Yoshiya, I.

1986-04-01

149

Mechanism of oxidative stress generation in cells by localized near-infrared femtosecond laser excitation  

NASA Astrophysics Data System (ADS)

We examined the effect of femtosecond (fs) and continuous wave (CW) lasers at near-infrared range on the creation of reactive oxygen species in a human liver cancer cell line. By controlling the mitochondria electron transport chain (ETC), it was found that a major part of the oxidative stress was generated by the laser induced thermal effect on the mitochondria while the remaining part was created by direct free electron liberation by the fs pulses, which could be observed after breaking the ETC. The study helps clarify the major effects produced on animal cells when excited by fs lasers.

He, Hao; Chan, Kam Tai; Kong, Siu Kai; Lee, Rebecca Kit Ying

2009-12-01

150

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

PubMed Central

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

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

2009-01-01

151

4. ANDERSON STREET SCHOOL, 1300 BLOCK BULL STREET, DETAIL OF ...  

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

4. ANDERSON STREET SCHOOL, 1300 BLOCK BULL STREET, DETAIL OF FENCE - Savannah Victorian Historic District, Bounded by Gwinnett, East Broad, West Broad Street & Anderson Lane, Savannah, Chatham County, GA

152

3. ANDERSON STREET SCHOOL, 1300 BLOCK BULL STREET, DETAIL OF ...  

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

3. ANDERSON STREET SCHOOL, 1300 BLOCK BULL STREET, DETAIL OF NORTH ELEVATION - Savannah Victorian Historic District, Bounded by Gwinnett, East Broad, West Broad Street & Anderson Lane, Savannah, Chatham County, GA

153

Local structural changes in excited Ti3+:Al2O3 studied by time-resolved XANES  

NASA Astrophysics Data System (ADS)

Transient changes in the local structure of optically excited Ti3+ ions in a Al2O3 single crystal are studied by time-resolved x-ray absorption spectroscopy. A model considering coupling of the excited E2(C3v) electronic state of the Ti3+ ion to the approximate A1g(Oh) and Eg(Oh) local vibrational modes of the TiO6 octahedron is constructed to fit the experimental data. We determine the magnitude of the A1g(Oh) mode and give an estimate of the Eg(Oh) Jahn-Teller distortion although this analysis does not distinguish between compression and elongation of the oxygen octahedron. Assuming a compressed octahedron, the Eg(Oh) distortion is found to be 0.14±0.02Å with an A1g(Oh) mode of 0.066±0.006Å . In the case of an elongated octahedron the Eg(Oh) distortion is -0.195±0.017Å with an A1g(Oh) mode of 0.052±0.002Å .

Vorobeva, E.; Johnson, S. L.; Beaud, P.; Milne, C. J.; Benfatto, M.; Ingold, G.

2009-10-01

154

Proteomic profiling of neuromas reveals alterations in protein composition and local protein synthesis in hyper-excitable nerves  

PubMed Central

Neuropathic pain may arise following peripheral nerve injury though the molecular mechanisms associated with this are unclear. We used proteomic profiling to examine changes in protein expression associated with the formation of hyper-excitable neuromas derived from rodent saphenous nerves. A two-dimensional difference gel electrophoresis (2D-DIGE) profiling strategy was employed to examine protein expression changes between developing neuromas and normal nerves in whole tissue lysates. We found around 200 proteins which displayed a >1.75-fold change in expression between neuroma and normal nerve and identified 55 of these proteins using mass spectrometry. We also used immunoblotting to examine the expression of low-abundance ion channels Nav1.3, Nav1.8 and calcium channel ?2?-1 subunit in this model, since they have previously been implicated in neuronal hyperexcitability associated with neuropathic pain. Finally, S35methionine in vitro labelling of neuroma and control samples was used to demonstrate local protein synthesis of neuron-specific genes. A number of cytoskeletal proteins, enzymes and proteins associated with oxidative stress were up-regulated in neuromas, whilst overall levels of voltage-gated ion channel proteins were unaffected. We conclude that altered mRNA levels reported in the somata of damaged DRG neurons do not necessarily reflect levels of altered proteins in hyper-excitable damaged nerve endings. An altered repertoire of protein expression, local protein synthesis and topological re-arrangements of ion channels may all play important roles in neuroma hyper-excitability.

Huang, Hong-Lei; Cendan, Cruz-Miguel; Roza, Carolina; Okuse, Kenji; Cramer, Rainer; Timms, John F; Wood, John N

2008-01-01

155

Upper Critical Field and Critical Temperature for Superconducting Alloys Described by the Anderson Model.  

National Technical Information Service (NTIS)

Extending some recent work by H. Shiba the authors have used the Hartree-Fock approximation for the Anderson Model of localized impurity electron states in a superconductor to obtain expressions for the critical temperature in zero magnetic field and for ...

G. B. Arnold

1974-01-01

156

MD Anderson researchers find that chemotherapy is as effective before breast cancer surgery as after  

Cancer.gov

Whether chemotherapy is given before or after breast-conserving therapy does not have an impact on long-term local-regional outcomes, suggesting treatment success is due more to biologic factors than chemotherapy timing, according to a study by researchers at The University of Texas MD Anderson Cancer Center.

157

Ferromagnetism and Kondo Insulator Behavior in the Disordered Periodic Anderson Model  

Microsoft Academic Search

The effect of binary alloy disorder on the ferromagnetic phases of f-electron materials is studied within the periodic Anderson model. We find that disorder in the conduction band can drastically enhance the Curie temperature Tc due to an increase of the local f moment. The effect may be explained qualitatively and even quantitatively by a simple theoretical ansatz. The emergence

Unjong Yu; Krzysztof Byczuk; Dieter Vollhardt

2008-01-01

158

MD Anderson study finds side effects, complications, and mastectomy are more likely after partial breast irradiation:  

Cancer.gov

Accelerated partial breast irradiation (APBI) brachytherapy, the localized form of radiation therapy growing increasingly popular as a treatment choice for women with early-stage breast cancer, is associated with higher rate of later mastectomy, increased radiation-related toxicities and post-operative complications, compared to traditional whole breast irradiation (WBI), according to researchers from The University of Texas MD Anderson Cancer Center.

159

The effect of the exhaustion on the magnetic and optical properties of the periodic Anderson model  

Microsoft Academic Search

We are interested in the study of the “exhaustion problem”, as originally introduced by Nozières, in the Kondo regime, and its manifestations on the magnetic and optical properties of the periodic Anderson model (PAM). In the case of the impurity problem there is only one single energy scale governed by the Kondo temperature TK, below which the local moment is

M. S. Figueira; J. Silva-Valencia; R. Franco

2008-01-01

160

Excite Travel  

NSDL National Science Digital Library

Excite Travel is one of the most comprehensive international guides to communities around the world. Excite Travel provides easy and timely access to information on travel, entertainment, and local business, plus government and community services for all regions of the world.

1998-01-01

161

Taking on Titan: Meet Carrie Anderson  

NASA Video Gallery

When she was a little girl, Carrie Anderson dreamed of becoming an astronomer. Now, as a space scientist at NASA Goddard Space Flight Center, Carrie studies the atmosphere on Titan: one of Saturn's moons and the second largest moon in the solar system. Titan is also a model for what the early Earth might have been like.

Genna Duberstein

2010-12-15

162

Controlling Spiral Dynamics in Excitable Media by a Weakly Localized Pacing  

Microsoft Academic Search

Spiral dynamics controlled by a weakly localized pacing around the spiral tip is investigated. Numerical simulations show two distinct characteristics when the pacing is applied with the weak amplitude for suitable frequencies: for a rigidly rotating spiral, a transition from rigid rotation to meandering motion is observed, and for unstable spiral waves, spiral breakup can be prevented. Successfully preventing spiral

Bing-Wei Li; Li-Li Sun; Bin Chen; He-Ping Ying

2007-01-01

163

The Anderson Quin Cycle. Final report  

SciTech Connect

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

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

1993-03-18

164

Localized excitations in competing bond-order-wave, charge-density-wave, and spin-density-wave systems  

NASA Astrophysics Data System (ADS)

The characteristics of localized excitations in quasi-one-dimensional systems are rather sensitive to the interplay between the electron-phonon (e-ph) and electron-electron (e-e) interactions giving rise to competition and possible coexistence of various symmetry-broken ground states such as the bond-order wave (BOW), the charge-density wave (CDW), and the spin-density wave (SDW). Such effects are observable in halogen-bridged mixed-valence transition-metal complexes, and can be elucidated within the Bogoliubov-de Gennes formalism using an extended Peierls-Hubbard model. The coexistence of local BOW, CDW, and SDW distortions is demonstrated in this paper for polarons and self-trapped excitons (STE) in different symmetry-broken ground states. An extensive study of localized excitations over a wide range of the on-site e-ph coupling ?2 and the Hubbard interaction U leads to the following observations. (a) As ?2 increases at fixed U, the number of bound states inside the gap changes from two to four for the STE case and from two to three for the polaron case. (b) Upon its further increase, one type of STE with a certain pattern of SDW distortion and charge transfer is transforming into another type of STE with a different pattern. (c) A nonmonotonic dependence of the lattice relaxation energy on ?2 is predicted within the lattice relaxation approach developed by Su and Yu earlier, and is attributed to a crossover from the weak-coupling to strong-coupling behavior showing up as the emergence of new bound states inside the gap. Moreover, the nonradiative transition rate of STE is also calculated and is used to tentatively interpret the very short lifetime of STE in PtCl complexes. Such nonmonotonic dependence of the relaxation rate on the coupling constant may also be observed in other quasi-one-dimensional systems as well.

Wang, Chui-Lin; Wang, Wen-Zheng; Gu, Guo-Liang; Su, Zhao-Bin; Yu, Lu

1993-10-01

165

Vibrational Excitations of Methane in the Framework of a Local-Mode Anharmonic Model  

NASA Astrophysics Data System (ADS)

The stretching and bending vibrations of methane are described in a local-mode anharmonic symmetry adapted model. Both Hecht- and Fermi-like interactions are considered. We start by establishing the Hamiltonian of the system in terms of internal coordinates and momenta. The Hamiltonian is then rewritten in terms of local creation (annihilation) operators a†i(ai), which are later anharmonized by means of the deformation of the harmonic oscillator algebra to the U(2) algebra. This procedure corresponds to the exact Morse result for the dominant matrix elements involved in the harmonically coupled anharmonic oscillator model (HCAO) introduced by Child and Lawton. We have carried out a fit to 40 experimental levels with an rms deviation of 1.17 cm-1. In addition, we present a description of the dipole transition intensities.

Lemus, R.; Frank, A.

2000-06-01

166

Suppression of Turbulent Dynamics in Models of Cardiac Tissue by Weak Local Excitations  

Microsoft Academic Search

On the basis of a modified FitzHugh-Nagumo system and a quite realistic ionic Fenton-Karma model describing the wave propagation\\u000a in cardiac tissue we resolve the problem of suppressing the fibrillative activity of the heart by a low-voltage local electrical\\u000a forcing. Such a low-energy defibrillation has a great advantage in comparison with other widespread methods since it, in particular,\\u000a does not

E. Zhuchkova; B. Radnayev; S. Vysotsky; A. Loskutov

167

Nonlinear excitation of low-n harmonics in reduced magnetohydrodynamic simulations of edge-localized modes  

NASA Astrophysics Data System (ADS)

Nonlinear simulations of the early edge-localized mode (ELM) phase based on a typical type-I ELMy ASDEX Upgrade discharge have been carried out using the reduced MHD code JOREK. The analysis is focused on the evolution of the toroidal Fourier spectrum. It is found that during the nonlinear evolution, linearly subdominant low-n Fourier components, in particular the n = 1, grow to energies comparable with linearly dominant harmonics. A simple model is developed, based on the idea that energy is transferred among the toroidal harmonics via second order nonlinear interaction. The simple model reproduces and explains very well the early nonlinear evolution of the toroidal spectrum in the JOREK simulations. Furthermore, it is shown for the n = 1 harmonic, that its spatial structure changes significantly during the transition from linear to nonlinearly driven growth. The rigidly growing structure of the linearly barely unstable n = 1 reaches far into the plasma core. In contrast, the nonlinearly driven n = 1 has a rigidly growing structure localized at the plasma edge, where the dominant toroidal harmonics driving the n = 1 are maximal and in phase. The presented quadratic coupling model might explain the recent experimental observation of strong low-n components in magnetic measurements [Wenninger et al., ``Non-linear magnetic perturbations during edge localized modes in TCV dominated by low n mode components,'' Nucl. Fusion (submitted)].

Krebs, I.; Hölzl, M.; Lackner, K.; Günter, S.

2013-08-01

168

Topology, Delocalization via Average Symmetry and the Symplectic Anderson Transition  

NASA Astrophysics Data System (ADS)

A field theory of the Anderson transition in two dimensional disordered systems with spin-orbit interactions and time-reversal symmetry is developed, in which localization is driven by the proliferation of vortex-like topological defects. The sign of the vortex fugacity determines the Z2 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 a N=1-? expansion in the number of replicas, where for small ? 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.

Kane, Charles; Fu, Liang

2013-03-01

169

Topology, delocalization via average symmetry and the symplectic Anderson transition.  

PubMed

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

Fu, Liang; Kane, C L

2012-12-14

170

Chiral Condensate and Mott-Anderson Freeze-Out  

NASA Astrophysics Data System (ADS)

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.

Blaschke, D.; Berdermann, J.; Cleymans, J.; Redlich, K.

2012-07-01

171

Localized excitations in a nonlinearly coupled magnetic drift wave-zonal flow system  

NASA Astrophysics Data System (ADS)

We consider the amplitude modulation of the magnetic drift wave (MDW) by zonal flows (ZFs) in a nonuniform magnetoplasma. For this purpose, we use the two-fluid model to derive a nonlinear Schrödinger equation for the amplitude modulated MDWs in the presence of the ZF potential, and an evolution equation for the ZF potential which is reinforced by the nonlinear Lorentz force of the MDWs. Our nonlinearly coupled MDW-ZFs system of equations admits stationary solutions in the form of a localized MDW envelope and a shock-like ZF potential profile.

Shukla, Nitin; Shukla, P. K.

2010-03-01

172

Localized electrostatic excitations in a Thomas-Fermi plasma containing degenerate electrons  

SciTech Connect

By using the Thomas-Fermi electron density distribution for quantum degenerate electrons, the hydrodynamic equations for ions, and the Poisson equation, planar and nonplanar ion-acoustic solitary waves in an unmagnetized collisionless plasma are investigated. The reductive perturbation method is used to derive cylindrical and spherical Korteweg-de Vries equations. Numerical solutions of the latter are presented. The present results can be useful in understanding the features of small but finite amplitude localized ion-acoustic solitary pulses in a degenerate plasma.

Abdelsalam, U. M. [Fakultaet fuer Mathematik, Ruhr-Universitaet Bochum, D-44780 Bochum (Germany); Moslem, W. M.; Shukla, P. K. [Institut fuer Theoretische Physik IV, Fakultaet fuer Physik und Astronomie, Ruhr-Universitaet Bochum, D-44780 Bochum (Germany)

2008-05-15

173

MgB2 nonlinear properties investigated under localized high rf magnetic field excitation  

NASA Astrophysics Data System (ADS)

The high transition temperature and low surface resistance of MgB2 attracts interest in its potential application in superconducting radio frequency accelerating cavities. However, compared to traditional Nb cavities, the viability of MgB2 at high rf fields is still open to question. Our approach is to study the nonlinear electrodynamics of the material under localized rf magnetic fields. Because of the presence of the small superconducting gap in the ? band, the nonlinear response of MgB2 at low temperature is potentially complicated compared to a single-gap s-wave superconductor such as Nb. Understanding the mechanisms of nonlinearity coming from the two-band structure of MgB2, as well as extrinsic sources of nonlinearity, is an urgent requirement. A localized and strong rf magnetic field, created by a magnetic write head, is integrated into our nonlinear-Meissner-effect scanning microwave microscope [T. Tai , IEEE Trans. Appl. Supercond. 21, 2615 (2011)ITASE91051-822310.1109/TASC.2010.2096531]. MgB2 films with thickness 50 nm, fabricated by a hybrid physical-chemical vapor deposition technique on dielectric substrates, are measured at a fixed location and show a strongly temperature-dependent third harmonic response. We propose that several possible mechanisms are responsible for this nonlinear response.

Tai, Tamin; Ghamsari, B. G.; Tan, T.; Zhuang, C. G.; Xi, X. X.; Anlage, Steven M.

2012-12-01

174

Subradiant hybrid states in the open 3D Anderson-Dicke model  

NASA Astrophysics Data System (ADS)

Anderson localization is a paradigmatic coherence effect in disordered systems, often analyzed in the absence of dissipation. Here we consider the case of coherent dissipation, occurring for open system with coupling to a common decay channel. This dissipation induces cooperative Dicke super- and subradiance and an effective long-range hopping, expected to destroy Anderson localization. We are thus in the presence of two competing effects, i.e. localization driven by disorder and delocalization driven by dissipative opening. Here we demonstrate the existence of a subradiant hybrid regime, emerging from the interplay of opening and disorder, in which subradiant states are hybrid with both features of localized and extended states, while superradiant states are extended. We also provide analytical predictions for this regime, confirmed by numerical simulations.

Biella, A.; Borgonovi, F.; Kaiser, R.; Celardo, G. L.

2013-09-01

175

Lithium abundances of halo dwarfs based on excitation temperature. I. Local thermodynamic equilibrium  

NASA Astrophysics Data System (ADS)

Context: The discovery of the Spite plateau in the abundances of 7Li for metal-poor stars led to the determination of an observationally deduced primordial lithium abundance. However, after the success of the Wilkinson Microwave Anisotropy Probe (WMAP) in determining the baryon density, ?_Bh2, there was a discrepancy between observationally determined and theoretically determined abundances in the case of 7Li. One of the most important uncertain factors in the calculation of the stellar 7Li abundance is the effective temperature, T_eff. Aims: We use sixteen metal-poor halo dwarfs to calculate new T_eff values using the excitation energy method. With this temperature scale we then calculate new Li abundances for this group of stars in an attempt to resolve the 7Li discrepancy. Methods: Using high signal-to-noise (S/N ? 100) spectra of 16 metal-poor halo dwarfs, obtained with the UCLES spectrograph on the AAT, measurements of equivalent widths from a set of unblended Fe I lines are made. These equivalent widths are then used to calculate new T_eff values with the use of the single line radiative transfer program WIDTH6, where we have constrained the gravity using either theoretical isochrones or the Hipparcos parallax, rather than the ionization balance. The lithium abundances of the stars are calculated with these temperatures. Results: The physical parameters are derived for the 16 programme stars, and two standards. These include T_eff, log g, [Fe/H], microturbulence and 7Li abundances. A comparison between the temperature scale of this work and those adopted by others has been undertaken. We find good consistency with the temperatures derived from the H? line by Asplund et al. (2006, ApJ, 644, 229), but not with the hotter scale of Meléndez & Ramírez (2004, ApJ, 615, L33). We also present results of the investigation into whether any trends between 7Li and metallicity or temperature are present in these metal-poor stars. Appendix A is only available in electronic form at the CDS via anonymous ftp to cdsarc.u-strasbg.fr (130.79.128.5) or via http://cdsweb.u-strasbg.fr/cgi-bin/qcat?J/A+A/493/601

Hosford, A.; Ryan, S. G.; García Pérez, A. E.; Norris, J. E.; Olive, K. A.

2009-01-01

176

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

NASA Astrophysics Data System (ADS)

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.

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

2004-03-01

177

Price-Anderson Act: Congressional review begins  

SciTech Connect

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.

Not Available

1984-07-05

178

Anderson-Darling Test based CFAR Detection  

Microsoft Academic Search

An Anderson-Darling(A-D) test based CFAR detector feasible for multiple interfering targets and clutter edge scenarios is proposed and referred as AD-CFAR, which exploits K-sample A-D hypothesis test technique to censor clutter blocks needed for power estimation. Thereafter, AD test is employed for distribution test of the resultant homogenous blocks to select the proper detection algorithm from strategy library composed by

Zhang Wei; Zhang Gong; Qian Guoming

2009-01-01

179

Lithium abundances of halo dwarfs based on excitation temperatures. II. Non-local thermodynamic equilibrium  

NASA Astrophysics Data System (ADS)

Context. The plateau in the abundance of 7Li in metal-poor stars was initially interpreted as an observational indicator of the primordial lithium abundance. However, this observational value is in disagreement with that deduced from calculations of Big Bang nucleosynthesis (BBN), when using the Wilkinson microwave anisotropy probe (WMAP) baryon density measurements. One of the most important factors in determining the stellar lithium abundance is the effective temperature. In a previous study by the authors, new effective temperatures (Teff) for sixteen metal-poor halo dwarfs were derived using a local thermodynamic equilibrium (LTE) description of the formation of Fe lines. This new Teff scale reinforced the discrepancy. Aims: For six of the stars from our previous study we calculate revised temperatures using a non-local thermodynamic equilibrium (NLTE) approach. These are then used to derive a new mean primordial lithium abundance in an attempt to solve the lithium discrepancy. Methods: Using the code MULTI we calculate NLTE corrections to the LTE abundances for the Fe i lines measured in the six stars, and determine new Teff's. We keep other physical parameters, i.e. log g, [Fe/H] and ?, constant at the values calculated in Paper I. With the revised Teff scale we derive new Li abundances. We compare the NLTE values of Teff with the photometric temperatures of Ryan et al. (1999, ApJ, 523, 654), the infrared flux method (IRFM) temperatures of Meléndez & Ramírez (2004, ApJ, 615, L33), and the Balmer line wing temperatures of Asplund et al. (2006, ApJ, 644, 229). Results: We find that our temperatures are hotter than both the Ryan et al. and Asplund et al. temperatures by typically ~110-160 K, but are still cooler than the temperatures of Meléndez & Ramírez by typically ~190 K. The temperatures imply a primordial Li abundance of 2.19 dex or 2.21 dex, depending on the magnitude of collisions with hydrogen in the calculations, still well below the value of 2.72 dex inferred from WMAP + BBN. We discuss the effects of collisions on trends of7Li abundances with [Fe/H] and Teff, as well as the NLTE effects on the determination of log g through ionization equilibrium, which imply a collisional scaling factor SH > 1 for collisions between Fe and H atoms.

Hosford, A.; García Pérez, A. E.; Collet, R.; Ryan, S. G.; Norris, J. E.; Olive, K. A.

2010-02-01

180

Boson localization and excitations of liquid {sup 4}He confined in gelsil  

SciTech Connect

We present neutron scattering measurements of the phonon-roton (P-R) modes of liquid {sup 4}He at saturated vapor pressure confined in 44 A mean pore diameter gelsil in the wave vector range 0.4{<=}Q{<=}2.15 A{sup -1}. Layer modes, modes which propagate in the liquid layers adjacent to the porous media walls, were also observed at wave vectors in the roton region (Q{approx_equal}1.95 A{sup -1}) but not at Q < or approx. 1.7 A{sup -1}. The first goal is to document the filling dependence of the dynamic response and of the P-R mode energies and widths more systematically than has been done in the past. As the gelsil is filled with {sup 4}He, the P-R and layer modes are first observed at a fractional filling of f=76% at low temperature (T=0.4 K). At fillings f=76%, the P-R mode energies lie below the bulk superfluid {sup 4}He values in the wave vector range 0.4{<=}Q{<=}1.7 A{sup -1}, especially at Q{approx_equal}1.1 A{sup -1}, as observed in helium films. As filling is increased, the intensity in the P-R mode increases markedly and the P-R mode energies move toward bulk superfluid values taking bulk values at full filling. The second goal is to determine the temperature dependence of the intensity in the P-R modes in a media in which the superfluid-normal transition temperature T{sub c}=1.92 K is independently known and lies well below the bulk liquid value T{sub {lambda}}=2.17 K. As temperature is increased, the intensity in the P-R and layer modes decreases. However, a well-defined P-R mode is observed at temperatures up to T{approx_equal}2.15 K, above T{sub c}=1.92 K. Since well-defined modes exist because there is Bose-Einstein condensation (BEC), this suggests that there is BEC above T{sub c}, probably localized. Localized BEC appears to exist up to T{approx_equal}T{sub {lambda}}.

Albergamo, Francesco [European Synchrotron Radiation Facility, Boite Postale 220, F-38043 Grenoble Cedex (France); Bossy, Jacques [Centre de Recherche sur les Tres Basses Temperatures, CNRS, BP 166, 38042 Grenoble Cedex 9 (France); Pearce, Jonathan V. [Institut Laue-Langevin, BP 156, 38042 Grenoble (France); Department of Physics and Astronomy, University of Delaware, Newark, Delaware 19716-2570 (United States); Schober, Helmut [Institut Laue-Langevin, BP 156, 38042 Grenoble (France); Glyde, Henry R. [Department of Physics and Astronomy, University of Delaware, Newark, Delaware 19716-2570 (United States)

2007-08-01

181

The Effect of Interband Excitations on Time-Resolved Two-Photon Photoemission via a Localized State at a Metal Surface  

NASA Astrophysics Data System (ADS)

The effect of interband excitations on time-resolved two-photon photoemission from an adsorbate-surface system is investigated. The system is assumed to be composed of two subbands in the bulk and a localized state of the adsorbate, which is in resonance with the upper energy subband. In the two-photon photoemission process, first, an electron in the lower energy subband is excited into the localized state by the pump photon, and subsequently excited above the vacuum level by the probe photon. The first excitation can be divided into two processes, i.e., the direct and the indirect one involving the interband excitation. The excitation probability due to the latter process reaches a maximum at a certain photon energy because of momentum conservation. A two-photon photoemission spectrum shows a peak due to the indirect process at an energy position where the initial state is fixed, as well as one due to the direct process where the intermediate state is fixed. The maximum of the cross-correlation trace of the pump and probe pulses (the pump-probe delay dependence of the photoelectron intensity) at the former peak shows little shift compared to that at the latter one. The intensity of the peak due to the indirect process increases as the pulse duration is decreased.

Sakaue, Mamoru; Kasai, Hideaki; Okiji, Ayao

1998-06-01

182

Field-controlled magnetic order with insulator-metal transitions in a periodic Anderson-like organic polymer.  

PubMed

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

Ding, L J; Yao, K L; Fu, H H

2010-10-29

183

Identification of a dominant mechanism for optical spin injection from a diluted magnetic semiconductor: Spin-conserving energy transfer via localized excitations  

NASA Astrophysics Data System (ADS)

We provide compelling experimental evidence for a spin-conserving energy-transfer process via localized excitations as being responsible for the observed optical spin injection in ZnMnSe/ZnCdSe quantum structures. We show that such a process is common and inherent to a diluted magnetic semiconductor because of strong potential fluctuations.

Chen, W. M.; Buyanova, I. A.; Kayanuma, K.; Nishibayashi, K.; Seo, K.; Murayama, A.; Oka, Y.; Toropov, A. A.; Lebedev, A. V.; Sorokin, S. V.; Ivanov, S. V.

2005-08-01

184

John Anderson’s development of (situational) realism and its bearing on psychology today  

Microsoft Academic Search

In 1927, the Scottish philosopher John Anderson arrived in Australia to take up the chair of Philosophy at the University of Sydney. By the late 1930s, the ‘macrostructure’ of his realist system was in place. It includes a theory of process and a substantial metaphysics, one that opposes positivism, linguistic philosophy and all forms of idealism. However, beyond Australia it

Fiona J. Hibberd

2009-01-01

185

Historical and Architectural Survey of Anderson County, South Carolina.  

National Technical Information Service (NTIS)

TRC, Inc. conducted a historic resources survey of Anderson County, South Carolina. The work was undertaken on behalf of the County of Anderson and was funded by a matching grant provided by South Carolina Department of Parks, Recreation, and Tourism (PRT...

J. S. Revels M. Sherrer

2002-01-01

186

Practice Effects and Composition: A Reply to Anderson  

Microsoft Academic Search

Anderson (1989) argues that our results (Carlson, Sullivan, & Schneider, 1989) confirm several predictions of the ACT* account of skill acquisition, including the occurrence of composition. The ACT* theory does include mechanisms that can account for the major ordinal results of our experiment. However, the quantitative implications of the mechanisms that Anderson invokes to support the occurrence of composition result

Richard A. Carlson; Walter Schneider

1989-01-01

187

Note on Anderson's "Causal Models in Educational Research: Nonrecursive Models."  

ERIC Educational Resources Information Center

|Contrary to Anderson (EJ 187 936), his rule for equation identification is a necessary but not sufficient condition; furthermore, the choice of two-stage or ordinary least squares depends on results and not on methodological properties of estimators. Modification of Anderson's rule and a means for choosing between estimates is offered.…

Shapiro, Jonathan

1979-01-01

188

ESR of a magnetic impurity in the Anderson model  

Microsoft Academic Search

The renormalization group technique is applied to calculate the ESR spin relaxation rate T1-1 of a well-defined magnetic moment in the neighborhood of a spin degenerate Anderson impurity. The effect of the Anderson impurity on T1-1 is analyzed by varying continuously its configuration from doubly to singly occupied, spotlighting the intermediate valence and the Kondo regime.

J. W. M. Pinto; H. O. Frota

2001-01-01

189

ESR of a magnetic impurity in the Anderson model  

Microsoft Academic Search

The renormalization group technique is applied to calculate the ESR spin relaxation rate T1?1 of a well-defined magnetic moment in the neighborhood of a spin degenerate Anderson impurity. The effect of the Anderson impurity on T1?1 is analyzed by varying continuously its configuration from doubly to singly occupied, spotlighting the intermediate valence and the Kondo regime.

J. W. M Pinto; H. O Frota

2001-01-01

190

Magnetic field induced quantum phase transitions in the two-impurity Anderson model  

SciTech Connect

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.

Zhu, Lujun [Los Alamos National Laboratory; Zhu, Jian - Xin [Los Alamos National Laboratory

2010-11-17

191

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

ERIC Educational Resources Information Center

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…

Albert, Marc K.

2008-01-01

192

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

ERIC Educational Resources Information Center

|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…

Albert, Marc K.

2008-01-01

193

The Anderson Reservoir seismic gap - Induced aseismicity?  

USGS Publications Warehouse

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.

Bufe, C. G.

1976-01-01

194

Synergy Effects of Electric and Magnetic Fields on Locally Excited-State Fluorescence of Photoinduced Electron Transfer Systems in a Polymer Film  

Microsoft Academic Search

Photoluminescence of electron donor-acceptor pairs that show photoinduced electron transfer (PIET) has been measured in a polymer film under simultaneous application of electric field and magnetic field. Fluorescence emitted from the locally excited state (LE fluorescence) of 9-methylanthracene (MAnt) and pyrene (Py) is quenched by an electric field in a mixture of 1,3-dicyanobenzene (DCB) with MAnt or Py, indicating that

Kamlesh Awasthi; Toshifumi Iimori; Nobuhiro Ohta

2009-01-01

195

Renormalization-group approach to spectral properties of the two-channel Anderson impurity model  

NASA Astrophysics Data System (ADS)

The impurity Green function and dynamical susceptibilities for the two-channel Anderson impurity model are calculated. An exact expression for the self-energy of the impurity Green function as ratio of two correlation functions is given. The imaginary part of the self-energy scales as ??/TK? for T?0 , serving as a hallmark for non-Fermi behavior. The many-body resonance is pinned to a universal value of 1/(2??) at ?=0 for arbitrary local occupation in contrary to the single-channel Anderson impurity model. Its shape becomes increasingly more symmetric for the Kondo regimes of the model. The dynamical spin and channel susceptibilities are governed by two energy scales TK and Th , and their ??(?) approach a constant value for ??0 .

Anders, Frithjof B.

2005-03-01

196

Bridge-mediated excitation energy transfer pathways through protein media: a Slater determinant-based electronic coupling calculation combined with localized molecular orbitals.  

PubMed

A computational method for calculating electronic coupling and pathway of electron transfer (ET) has been extended to that for excitation energy transfer (EET). A molecular orbital (MO)-based description has been generalized to one based on Slater determinants. This approach reduces the approximations used for the Green's function method from the perturbation of chemical-bond interactions to the perturbation of the configuration interactions. It is, therefore, reasonable to apply this method to EET, which involves the transfer of an electron-hole pair. To represent EET donor, acceptor, and bridge states, we adopted recently developed localized molecular orbitals (LMOs) for constructing locally excited determinants. The LMO approach provides a chemically meaningful interpretation of how each local excitation on the bridge contributes to the total electronic coupling of the EET. We applied the method to six model peptides and calculated their electronic couplings as well as the direct and through-peptide terms. Although the through-peptide term is usually negligibly small compared with the direct term, it can dominate the EET reaction in appropriate situations. The direct term dominates in long-range interactions because the indirect term decays in shorter distances. PMID:21861486

Kawatsu, Tsutomu; Matsuda, Kenji; Hasegawa, Jun-ya

2011-09-12

197

Critical State of the Anderson Transition: Between a Metal and an Insulator  

NASA Astrophysics Data System (ADS)

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.

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

2010-08-01

198

Critical State of the Anderson Transition: Between a Metal and an Insulator  

SciTech Connect

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.

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

199

Resonant charge-exchange involving excited helium atoms and reactive transport of local thermodynamic equilibrium helium plasma  

SciTech Connect

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.

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

200

Localized versus delocalized excitations just above the 3d threshold in krypton clusters studied by Auger electron spectroscopy.  

PubMed

We present Auger spectroscopy studies of large krypton clusters excited by soft x-ray photons with energies on and just above the 3d(52) ionization threshold. The deexcitation spectra contain new features as compared to the spectra measured both below and far above threshold. Possible origins of these extra features, which stay at constant kinetic energies, are discussed: (1) normal Auger process with a postcollision interaction induced energy shift, (2) recapture of photoelectrons into high Rydberg orbitals after Auger decay, and (3) excitation into the conduction band (or "internal" ionization) followed by Auger decay. The first two schemes are ruled out, hence internal ionization remains the most probable explanation. PMID:17902910

Tchaplyguine, M; Kivimäki, A; Peredkov, S; Sorensen, S L; Ohrwall, G; Schulz, J; Lundwall, M; Rander, T; Lindblad, A; Rosso, A; Svensson, S; Mårtensson, N; Björneholm, O

2007-09-28

201

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

PubMed

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

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

2013-10-22

202

The Universality Classes in the Parabolic Anderson Model  

NASA Astrophysics Data System (ADS)

We discuss the long time behaviour of the parabolic Anderson model, the Cauchy problem for the heat equation with random potential onmathbb{Z}d. We consider general i.i.d. potentials and show that exactly four qualitatively different types of intermittent behaviour can occur. These four universality classes depend on the upper tail of the potential distribution: (1) tails at ? that are thicker than the double-exponential tails, (2) double-exponential tails at ? studied by Gärtner and Molchanov, (3) a new class called almost bounded potentials, and (4) potentials bounded from above studied by Biskup and König. The new class (3), which contains both unbounded and bounded potentials, is studied in both the annealed and the quenched setting. We show that intermittency occurs on unboundedly increasing islands whose diameter is slowly varying in time. The characteristic variational formulas describing the optimal profiles of the potential and of the solution are solved explicitly by parabolas, respectively, Gaussian densities. Our analysis of class (3) relies on two large deviation results for the local times of continuous-time simple random walk. One of these results is proved by Brydges and the first two authors in [BHK04], and is also used here to correct a proof in [BK01].

van der Hofstad, Remco; König, Wolfgang; Mörters, Peter

2006-10-01

203

Anderson-Hubbard model in infinite dimensions  

NASA Astrophysics Data System (ADS)

We present a detailed, quantitative study of the competition between interaction- and disorder-induced effects in electronic systems. For this the Hubbard model with diagonal disorder (Anderson-Hubbard model) is investigated analytically and numerically in the limit of infinite spatial dimensions, i.e., within a dynamical mean-field theory, at half-filling. Numerical results are obtained for three different disorder distributions by employing quantum Monte Carlo techniques, which provide an explicit finite-temperature solution of the model in this limit. The magnetic phase diagram is constructed from the zeros of the inverse averaged staggered susceptibility. We find that at low enough temperatures and sufficiently strong interaction there always exists a phase with antiferromagnetic long-range order. A strong coupling anomaly, i.e., an increase of the Néel temperature for increasing disorder, is discovered. An explicit explanation is given, which shows that in the case of diagonal disorder this is a generic effect. The existence of metal-insulator transitions is studied by evaluating the averaged compressibility both in the paramagnetic and antiferromagnetic phases. A rich transition scenario, involving metal-insulator and magnetic transitions, is found and its dependence on the choice of the disorder distribution is discussed.

Ulmke, M.; Janiš, V.; Vollhardt, D.

1995-04-01

204

Remarks on the Hylleraas-Undheim and MacDonald Higher Roots, And Functional Having Local Minimum at The Excited States  

SciTech Connect

The excited states, being energy saddle points in the Hamiltonian eigenfunction Hilbert space, cannot be computed variationally by minimization of the energy. Thus, functionals are presented, that have local minimum at the bound excited states of a non-degenerate Hamiltonian, allowing the computation at any desired accuracy, by using crude approximations of the lower lying states. They are useful for larger systems, because the higher roots of the standard secular equation have, by the Hylleraas-Undheim and MacDonald theorem, several restrictions, which render them of lower quality relative to the lowest root, if the latter is good enough. Preliminary test-results are presented for He {sup 1}S 1s2s.

Bacalis, N. C.; Xiong, Z.; Karaoulanis, D. [Theoretical and Physical Chemistry Institute, National Hellenic Research Foundation, Vasileos Constantinou 48, GR-116 35 Athens (Greece)

2009-08-13

205

Renal involvement in Anderson-Fabry disease.  

PubMed

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

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

206

Local Thermomechanical Characterization of Phase Transitions in Polymers using Band Excitation Atomic Force Acoustic Microscopy with Heated Probe.  

SciTech Connect

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

Nikiforov, Maxim [ORNL

2008-01-01

207

CO2 non-local thermodynamic equilibrium radiative excitation and infrared dayglow at 4.3 micron: Application to Spectral Infrared Rocket Experiment data  

NASA Astrophysics Data System (ADS)

Infrared radiative excitation in non-local thermodynamic equilibrium (non-LTE) regions of the Earth's atmosphere for the V(sub 3) mode vibrationally excited states of CO2 under sunlit conditions and the resulting 4.3-microns limb radiance are calculated using a line-by-line (LBL) radiative transfer model. Excited-state popluation densities and the corresponding vibrational temperature profiles are calculated for the important emitting states using a model which includes radiative absorption and emission as well as various collisional processes. The quenching of O(D(1)/by N2 has a greater impact on these population densities than has been previously reported in the literature. Integrated radiance in a limb view for the 4.3-microns bands is calculated from the model and compared with sunlit earthlimb measurements obtained by the Spectral Infrared Rocket Experiment (SPIRE). Solar pumping is the dominant excitation process for the 4.3-micron emitting states in the daytime. The major contribution to the total limb radiance for tangent heights of 55-95 km is made by the flourescent states at approximately 3600/cm which absorb sunlight at 2.7 microns and then emit preferentially at 4.3 microns. The predicted radiance is in good agreement with the SPIRE measurements for all tangent heights in the 50- to 130-km range. This is the first detailed comparison of results of a full line-by-line non-LTE radiative transfer calculation with 4.3-microns earthlimb radiance data.

Nebel, Henry; Wintersteiner, Peter P.; Picard, R. H.; Winick, Jeremy R.; Sharma, Ramesh D.

1994-05-01

208

SU(3) Anderson impurity model: A numerical renormalization group approach exploiting non-Abelian symmetries  

NASA Astrophysics Data System (ADS)

We show how the density-matrix numerical renormalization group method can be used in combination with non-Abelian symmetries such as SU(N). The decomposition of the direct product of two irreducible representations requires the use of a so-called outer multiplicity label. We apply this scheme to the SU(3) symmetrical Anderson model, for which we analyze the finite size spectrum, determine local fermionic, spin, superconducting, and trion spectral functions, and also compute the temperature dependence of the conductance. Our calculations reveal a rich Fermi liquid structure.

Moca, C?t?lin Pa?cu; Alex, Arne; von Delft, Jan; Zaránd, Gergely

2012-11-01

209

Magnetic properties of the symmetric periodic Anderson model in infinite dimensions  

NASA Astrophysics Data System (ADS)

Within a special kind of slave-boson mean-field approximation, which allows for the symmetry-broken states appropriate for a bipartite lattice, it is found that there is a phase transition to the antiferromagnetic insulator for the symmetric periodic Anderson model, and the critical value of the hybridization matrix element is consistent with the quantum Monte Carlo result of Jarrell, Akhlaghpour, and Pruschke [Phys. Rev. Lett. 70, 1670 (1993)]. Our results suggest that the magnetism is itinerant near the critical value of the hybridization matrix element, and it smoothly crosses over to the local-moment regime as the hybridization decreases to zero.

Sun, Shih-Jye; Yang, Min-Fong; Hong, Tzay-Ming

1993-12-01

210

Dipole moment of water in highly vibrationally excited states: analysis of photofragment quantum-beat spectroscopy measurements using a local-mode hamiltonian.  

PubMed

We present here the analysis of experimental Stark effect measurements made using photofragment quantum beat spectroscopy on the |4,0(-)>, |5,0(-)>, |8,0(+)> and |4,0(-)>|2> vibrational states of H(2)O [ Callegari , A. ; et al. Science 2002 , 297 , 993.]. To link the measured Stark coefficients with the dipole surface, we analyze our results using a coupled anharmonic oscillator model, which takes into account the local-mode nature of higly excited OH stretching vibrations in water, and the tunneling between the two equivalent bonds. The large inertial frame tilt associated with the local-mode bond stretching results in a complex interaction between rotational-, vibrational-, and tunneling-motion, all of which become deeply entangled in the Stark coefficients. A perturbational approach makes it possible to analyze the problem at increasingly higher levels of approximation and to disentangle the different contributions, according to the different time scales involved. This simple model reproduces most experimental values to within a few percent, even for these highly vibrationally excited levels, and gives valuable insight into the complex rotational and vibrational motions that link the dipole moment surface with the Stark coefficients. PMID:19873972

Theule, Patrice; Muenter, John S; Callegari, Andrea

2009-11-26

211

Kinetics and subcellular localization of 5-ALA-induced PpIX in DHL cells via two-photon excitation fluorescence microscopy.  

PubMed

Two-photon excitation fluorescence (TPEF) microscopy was used to measure the 5-aminolevulinic acid (5-ALA)-induced PpIX fluorescence in follicular lymphoma DHL cells. Kinetics of 5-ALA-induced PpIX accumulation in DHL cells under various 5-ALA concentrations was studied. We found that during the course of continuous incubation with 5-ALA, the relationship between the DHL cell fluorescence signal and the incubation time showed a biphasic variation. Initially the PpIX signal increased with the incubation time and reached the maximal value at about 3 h, and then it decreased with time during the subsequent incubation period. By labeling the 5-ALA incubated DHL cells with different organelle-specific fluorescence probes: Rhodamine 123 (for mitochondria), DioC6(3) (for endoplasmic reticulum) and LysoTracker Green (for lysosomes) respectively, we found that 5-ALA-induced PpIX was primarily localized in endoplasmic reticulum and mitochondria; its concentration in the lysosome was much lower. The results suggested that 5-ALA could potentially be an effective photosensitizer in photodynamic purging of DHL cells. Two-photon excitation fluorescence microscope is a useful tool for studying 5-ALA-induced PpIX subcellular localization. PMID:18360713

Chen, Rong; Huang, Zufang; Chen, Guannan; Li, Yongzeng; Chen, Xianlian; Chen, Jianxin; Zeng, Haishan

2008-04-01

212

Neurological complications of anderson-fabry disease.  

PubMed

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

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

2013-01-01

213

The Innocence Project, Marvin AndersonSite: DNA Interactive (www.dnai.org)  

NSDL National Science Digital Library

Interviewee: Marvin Anderson DNAi Location:Applications>Human identification>Innocence>DNA and the Innocence Project On February 28, 2003, Marvin Anderson spoke at a function celebrating the 50th anniversary of the discovery of the structure of DNA.

2008-03-26

214

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

NASA Astrophysics Data System (ADS)

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

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

2012-12-01

215

Synergy Effects of Electric and Magnetic Fields on Locally Excited-State Fluorescence of Photoinduced Electron Transfer Systems in a Polymer Film  

NASA Astrophysics Data System (ADS)

Photoluminescence of electron donor-acceptor pairs that show photoinduced electron transfer (PIET) has been measured in a polymer film under simultaneous application of electric field and magnetic field. Fluorescence emitted from the locally excited state (LE fluorescence) of 9-methylanthracene (MAnt) and pyrene (Py) is quenched by an electric field in a mixture of 1,3-dicyanobenzene (DCB) with MAnt or Py, indicating that PIET from the excited state of MAnt or Py to DCB is enhanced by an electric field. Simultaneous application of electric and magnetic fields enhances the reverse process from the radical-ion pair produced by PIET to the LE fluorescent state of MAnt or Py. As a result, the electric-field-induced quenching of the LE fluorescence is reduced by application of the magnetic fields. Thus, the synergy effect of electric and magnetic fields is observed on the LE fluorescence of MAnt or Py. Exciplex fluorescence spectra resulting from PIET can be obtained by analyzing the field effects on photoluminescence spectra, even when the exciplex fluorescence is too weak to be determined from the steady-state or time-resolved photoluminescence spectra at zero field.

Awasthi, Kamlesh; Iimori, Toshifumi; Ohta, Nobuhiro

2009-09-01

216

Resonance Pacemakers in Excitable Media  

NASA Astrophysics Data System (ADS)

Chemical waves are initiated in an excitable medium by resonance with local periodic forcing of the excitability. Experiments are carried out with a photosensitive Belousov-Zhabotinsky medium, in which the excitability is varied according to the intensity of the imposed illumination. Complex resonance patterns are exhibited as a function of the amplitude and frequency of the forcing. Local resonance-induced wave initiation transforms the medium globally from a quiescent excitable steady state to a periodic state of successive traveling waves.

Chigwada, Tabitha Ruvarashe; Parmananda, P.; Showalter, Kenneth

2006-06-01

217

Modified Bose-Einstein and Fermi-Dirac statistics if excitations are localized on an intermediate length scale: Applications to non-Debye specific heat  

NASA Astrophysics Data System (ADS)

Disordered systems show deviations from the standard Debye theory of specific heat at low temperatures. These deviations are often attributed to two-level systems of uncertain origin. We find that a source of excess specific heat comes from correlations between quanta of energy if excitations are localized on an intermediate length scale. We use simulations of a simplified Creutz model for a system of Ising-like spins coupled to a thermal bath of Einstein-like oscillators. One feature of this model is that energy is quantized in both the system and its bath, ensuring conservation of energy at every step. Another feature is that the exact entropies of both the system and its bath are known at every step, so that their temperatures can be determined independently. We find that there is a mismatch in canonical temperature between the system and its bath. In addition to the usual finite-size effects in the Bose-Einstein and Fermi-Dirac distributions, if excitations in the heat bath are localized on an intermediate length scale, this mismatch is independent of system size up to at least 106 particles. We use a model for correlations between quanta of energy to adjust the statistical distributions and yield a thermodynamically consistent temperature. The model includes a chemical potential for units of energy, as is often used for other types of particles that are quantized and conserved. Experimental evidence for this model comes from its ability to characterize the excess specific heat of imperfect crystals at low temperatures.

Chamberlin, Ralph V.; Davis, Bryce F.

2013-10-01

218

A Management Analysis of the City of Anderson Transit System.  

National Technical Information Service (NTIS)

The basic purpose of the report is to evaluate the previous management structure of the City of Anderson Transportation System (CATS), and to identify and evaluate any changes which have occurred. The main focus of this document is the description of the ...

E. M. Demos

1978-01-01

219

10. VIEW OF SITE B FROM WEST END OF ANDERSON ...  

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

10. VIEW OF SITE B FROM WEST END OF ANDERSON WAY, FACING NORTHEAST (BUILDINGS 131, 130, 129, and 128 ARE VISIBLE.) - Fort McPherson, World War II Station Hospital, Structures, Bordered by Hardee & Thorne Avenues & Howe Street, Atlanta, Fulton County, GA

220

9. VIEW OF SITE B FROM EAST END OF ANDERSON ...  

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

9. VIEW OF SITE B FROM EAST END OF ANDERSON WAY, FACING WEST (BUILDINGS 126, 128, 129, 130, and 131 ARE VISIBLE.) - Fort McPherson, World War II Station Hospital, Structures, Bordered by Hardee & Thorne Avenues & Howe Street, Atlanta, Fulton County, GA

221

6. VIEW OF SITE A FROM ANDERSON WAY NEAR BUILDING ...  

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

6. VIEW OF SITE A FROM ANDERSON WAY NEAR BUILDING 132, FACING SOUTHEAST (BUILDINGS 124, 122, 120, and 118 ARE VISIBLE.) - Fort McPherson, World War II Station Hospital, Structures, Bordered by Hardee & Thorne Avenues & Howe Street, Atlanta, Fulton County, GA

222

Multifractality at Anderson Transitions with Coulomb Interaction  

NASA Astrophysics Data System (ADS)

We explore mesoscopic fluctuations and correlations of the local density of states (LDOS) near localization transition in a disordered interacting electronic system. It is shown that the LDOS multifractality survives in the presence of the Coulomb interaction. We calculate the spectrum of multifractal dimensions in 2+? spatial dimensions and show that it differs from that in the absence of interaction. The multifractal character of fluctuations and correlations of the LDOS can be studied experimentally by scanning tunneling microscopy of two-dimensional and three-dimensional disordered structures.

Burmistrov, I. S.; Gornyi, I. V.; Mirlin, A. D.

2013-08-01

223

Louisa Garrett Anderson (1873-1943), surgeon and suffragette.  

PubMed

Louisa Garrett Anderson, daughter of Britain's first woman doctor, has been largely forgotten today despite the fact that her contribution to the women's movement was as great as that of her mother. Recognized by her contemporaries as an important figure in the suffrage campaign, Anderson chose to lend her support through high-profile action, being one of the few women doctors in her generation who risked their professional as well as their personal reputation in the fight for women's rights by becoming a suffragette - in her case, even going so far as to spend a month in prison for breaking a window on a demonstration. On the outbreak of war, with only the clinical experience she had gained as outpatient surgeon in a women's hospital, Anderson established a series of women-run military hospitals where she was a Chief Surgeon. The most successful was the Endell Street Military Hospital in London, funded by the Royal Army Medical Corps and the only army hospital ever to be run and staffed entirely by women. Believing that a doctor had an obligation to take a lead in public affairs, Anderson continued campaigning for women's issues in the unlikely setting of Endell Street, ensuring that their activities remained in the public eye through constant press coverage. Anderson's achievement was that her work played no small part in expunging the stigma of the militant years in the eyes of the public and - more importantly - was largely instrumental in putting women doctors on equal terms with their male colleagues. PMID:18952990

Geddes, Jennian F

2008-11-01

224

Pengujian Statistik Anderson Darling bagi Taburan Nilai Ekstrim Teritlak (The Anderson-Darling Test Statistic of the Generalized Extreme Value)  

Microsoft Academic Search

Abstrak Makalah ini mempersembahkan kajian untuk membangun dan menilai pen- gujian statistik Anderson-Darling (AD) dalam menguji kesesuaian taburan nilai ek- strim teritlak (GEV). Jadual nilai kritikal statistik AD dibangunkan berdasarkan khi- kuasa dua Pearson dan kebolehjadian statistik bagi taburan GEV menggunakan sim- ulasi Monte Carlo. Nilai kritikal statistik ini dimodelkan menggunakan persamaan regresi untuk menyediakan persamaan bagi menganggar nilai kritikal

Ani Shabri; Abdul Aziz Jemain

225

Kohn's localization in the insulating state: One-dimensional lattices, crystalline versus disordered  

NASA Astrophysics Data System (ADS)

The qualitative difference between insulators and metals stems from the nature of the low-lying excitations, but also-according to Kohn's theory [W. Kohn, Phys. Rev. 133, A171 (1964)]-from a different organization of the electrons in their ground state: electrons are localized in insulators and delocalized in metals. We adopt a quantitative measure of such localization, by means of a ``localization length'' ?, finite in insulators and divergent in metals. We perform simulations over a one-dimensional binary alloy model, in a tight-binding scheme. In the ordered case the model is either a band insulator or a band metal, whereas in the disordered case it is an Anderson insulator. The results show indeed a localized/delocalized ground state in the insulating/metallic cases, as expected. More interestingly, we find a significant difference between the two insulating cases: band versus Anderson. The insulating behavior is due to two very different scattering mechanisms; we show that the corresponding values of ? differ by a large factor for the same alloy composition. We also investigate the organization of the electrons in the many body ground state from the viewpoint of the density matrices and of Boys' theory of localization.

Bendazzoli, Gian Luigi; Evangelisti, Stefano; Monari, Antonio; Resta, Raffaele

2010-08-01

226

Finite size scaling of entanglement entropy at the Anderson transition with interactions  

NASA Astrophysics Data System (ADS)

We study the entanglement entropy(EE) of disordered one-dimensional spinless fermions with attractive interactions. With intensive numerical calculation of the EE using the density matrix renormalization group method, we find clear signatures of the transition between the localized and delocalized phase. In the delocalized phase, the fluctuations of the EE becomes minimum and independent of the system size. Meanwhile the EE's logarithmic scaling behavior is found to recover to that of a clean system. We present a general scheme of finite size scaling of the EE at the critical regime of the Anderson transition, from which we extract the critical parameters of the transition with good accuracy, including the critical exponent, critical point and a power-law divergent localization length.

Zhao, An

2013-03-01

227

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

SciTech Connect

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).

Giovannini, L.; Montoncello, F.; Nizzoli, F.; Vavassori, P.; Grimsditch, M. (Materials Science Division); (Dipartimento di Fisica); (CNISM); (Basque Foundation for Science)

2011-11-04

228

Observations of nighttime winds using pilot balloons in Anderson Creek Valley, Geysers, California  

SciTech Connect

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.

Nappo, C.J.; Snodgrass, H.F.

1981-06-01

229

Lattice density functional theory of the single-impurity Anderson model: Development and applications  

NASA Astrophysics Data System (ADS)

A lattice density functional theory (LDFT) of the single-impurity Anderson model is presented. In this approach the basic variable is the single-particle density matrix ?ij with respect to the lattice sites and the fundamental unknown functional is the Coulomb interaction energy W[?]. Using general symmetry properties, a two-level ansatz for W[?] in spin-restricted systems is proposed which involves explicitly only the impurity orbital and a single symmetry-adapted conduction-band state. A simple analytical functional dependence of W[?] is derived on the basis of exact results of this two-level problem. The resulting approximation is shown to be exact in two important opposite limits: a totally degenerate conduction band and a conduction band with widely separated discrete levels. Applications to finite rings having N?100 atoms yield very accurate results for ground-state properties such as the kinetic, interaction, and total energy, as well as the occupation and magnetic moment of the local impurity orbital. This holds for all considered interaction strengths, from weak to strong correlations, as well as in the Kondo and intermediate valence regimes. One concludes that the present two-level approximation provides an appropriate framework for investigating subtle electron-correlation effects of the Anderson model within LDFT.

Töws, W.; Pastor, G. M.

2011-06-01

230

Statistical properties of the one dimensional Anderson model relevant for the nonlinear Schrödinger equation in a random potential  

NASA Astrophysics Data System (ADS)

The statistical properties of overlap sums of groups of four eigenfunctions of the Anderson model for localization as well as combinations of four eigenenergies are computed. Some of the distributions are found to be scaling functions, as expected from the scaling theory for localization. These enable to compute the distributions in regimes that are otherwise beyond the computational resources. These distributions are of great importance for the exploration of the nonlinear Schrödinger equation (NLSE) in a random potential since in some explorations the terms we study are considered as noise and the present work describes its statistical properties.

Michaely, E.; Fishman, S.

2012-11-01

231

Categorization of nocturnal drainage flows in the Anderson Creek valley  

SciTech Connect

A network of eight meteorological towers was operated over about a one-year period within the Anderson Creek valley in the Geysers Geothermal Area of northern California. The purpose was to define the noctural wind and temperature structure along the valley's sloped surfaces for use in evaluating the frequency of drainage flows throughout the year and to assess the representativeness of the flows observed during the few nights that intensive studies were undertaken. (ACR)

Gudiksen, P.H.; Walton, J.J.

1981-06-01

232

Agalsidase Alfa in the Treatment of Anderson-Fabry Disease  

Microsoft Academic Search

\\u000a Agalsidase alfa is a formulation of the human enzyme ?-galactosidase A (AGAL), generated by activation of the encoding gene\\u000a in a continuous human cell line. The regular infusion of agalsidase alfa into patients with Anderson-Fabry disease (AFD),\\u000a in whom AGAL deficiency can lead to multi-organ system failure, has been demonstrated to be safe. By facilitating the clearance\\u000a of the substrate

Gregory M. Pastores

233

Spectra of Anderson type models with decaying randomness  

Microsoft Academic Search

In this paper we consider some Anderson type models, with free parts having long range tails and with the random perturbations\\u000a decaying at different rates in different directions and prove that there is a.c. spectrum in the model which is pure. In addition,\\u000a we show that there is pure point spectrum outside some interval. Our models include potentials decaying in

M. Krishna; K. B. Sinha

2001-01-01

234

Astronaut Clay Anderson Speaks With S.C. Students  

NASA Video Gallery

From NASA's International Space Station Mission Control Center, NASA astronaut Clay Anderson participates in a Digital Learning Network (DLN) event with students at Crayton Middle School, Columbia, S.C. The DLN connects students and teachers with NASA experts and education specialists using online communication technologies like video/web conferencing and webcasting. Register for free, interactive events listed in the catalog or watch the webcasts. http://dln.nasa.gov

Gerald T Wright

2012-10-04

235

Charge susceptibility of the spin-degenerate Anderson model  

Microsoft Academic Search

We calculated the charge susceptibility of the Anderson model for finite f-f Coulomb interaction U, via a renormalization-group technique. For an occupation number of the f orbital around unity, the spectrum presents two peaks. One peak is centered at the impurity orbital energy ||?f||, and comes from the transition f0-->f1. The other one is centered at the energy ?f+U. It

H. O. Frota

1991-01-01

236

MD Anderson researchers find coupling of proteins promotes glioblastoma development:  

Cancer.gov

Two previously unassociated proteins known to be overly active in a variety of cancers bind together to ignite and sustain malignant brain tumors, a research team led by scientists at The University of Texas MD Anderson Cancer Center reports this week in the journal Cancer Cell. This research is the first to connect FoxM1 to a molecular signaling cascade that regulates normal neural stem cells...

237

Full density-matrix numerical renormalization group calculation of impurity susceptibility and specific heat of the Anderson impurity model  

NASA Astrophysics Data System (ADS)

Recent developments in the numerical renormalization group (NRG) allow the construction of the full density matrix (FDM) of quantum impurity models [see A. Weichselbaum and J. von Delft, Phys. Rev. Lett.PRLTAO0031-900710.1103/PhysRevLett.99.076402 99, 076402 (2007)] by using the completeness of the eliminated states introduced by F. B. Anders and A. Schiller [F. B. Anders and A. Schiller, Phys. Rev. Lett.PRLTAO0031-900710.1103/PhysRevLett.95.196801 95, 196801 (2005)]. While these developments prove particularly useful in the calculation of transient response and finite-temperature Green's functions of quantum impurity models, they may also be used to calculate thermodynamic properties. In this paper, we assess the FDM approach to thermodynamic properties by applying it to the Anderson impurity model. We compare the results for the susceptibility and specific heat to both the conventional approach within NRG and to exact Bethe ansatz results. We also point out a subtlety in the calculation of the susceptibility (in a uniform field) within the FDM approach. Finally, we show numerically that for the Anderson model, the susceptibilities in response to a local and a uniform magnetic field coincide in the wide-band limit, in accordance with the Clogston-Anderson compensation theorem.

Merker, L.; Weichselbaum, A.; Costi, T. A.

2012-08-01

238

Test of the Singh-Anderson model of transparency.  

PubMed

A new model of achromatic transparency has been recently proposed by Singh and Anderson as an alternative to the model proposed long ago by Metelli. The study reported here compared these models using achromatic stimuli consisting of a transparent disk on a background formed by two adjoining rectangles, with the common border of the rectangles dividing the disk in half. Let a and b denote the luminances of the left and right parts of the background, respectively, and let p and q denote the luminances of the left and right parts of the disk, respectively. The value of b was varied for fixed values of a, p, and q. For these values the Singh-Anderson model predicts that the perceived extent of transparency T of the disk is constant with b, while Metelli's model predicts that T decreases as b increases. Participants rated T. The results confirm the prediction of Metelli's model. It is also shown that the Singh-Anderson model is invalid in principle in that, unlike Metelli's model, it fails to capture the principle of independence of the effects of a, b, p, and q on T. PMID:17879671

Masin, Sergio Cesare; Tommasi, Marco; Da Pos, Osvaldo

2007-06-01

239

Effects of cyclosis on chloroplast-cytoplasm interactions revealed with localized lighting in Characean cells at rest and after electrical excitation.  

PubMed

Cytoplasmic streaming in Characean internodes enables rapid intracellular transport and facilitates interactions between spatially remote cell regions. Cyclosis-mediated distant interactions might be particularly noticeable under nonuniform illumination, in the vicinity of light-shade borders where metabolites are transported between functionally distinct cell regions. In support of this notion, chlorophyll fluorescence parameters assessed on a microscopic area of Chara corallina internodal cells (area of inspection, AOI) responded to illumination of nearby regions in asymmetric manner depending on the vector of cytoplasmic streaming. When a beam of white light was applied through a 400-?m optic fiber upstream of AOI with regard to the direction of cytoplasmic streaming, non-photochemical quenching (NPQ) developed after a lag period in AOI exposed to moderate intensity light. Conversely, no NPQ was induced in the same cell area when the beam position was shifted to an equal distance downstream of AOI. Light-response curves for the efficiency of photosystem II electron transport in chloroplasts differed markedly depending on the illumination pattern (whole-cell versus small area illumination) but these differences were eliminated after the inhibition of cytoplasmic streaming with cytochalasin B. Localized illumination promoted chloroplast fluorescence responses to electrical plasmalemma excitation at high light intensities, which contrasts to the requirement of low to moderate irradiances for observation of the stimulus-response coupling under whole-cell illumination. The results indicate that different photosynthetic capacities of chloroplasts under general and localized illumination are related to lateral transport of nonevenly distributed cytoplasmic components between the cell parts with dominant photosynthetic and respiratory metabolism. PMID:21708122

Bulychev, Alexander A; Dodonova, Svetlana O

2011-06-25

240

Localized Etching of a Polyimide Film by an Atmospheric-Pressure Radio Frequency Microplasma Excited by a 100-?m-? Metal Pipe Electrode  

NASA Astrophysics Data System (ADS)

Atmospheric-pressure He and Ar microplasmas (?-plasmas) have been generated by a 14 MHz radio-frequency (RF) discharge using a metal narrow pipe electrode with an outer diameter of 100 ?m. The metal pipe acts as both a powered electrode and a gas nozzle. The discharge mode changed from a corona discharge to a glow discharge and finally to a thermal spot arc discharge with decreasing discharge gap between the pipe electrode and the grounded plate as well as with increasing RF power. The Ar glow ?-plasma was applied to the localized etching of a polyimide film with a thickness of 0.025 mm in air ambient. The etched spot showed an isotropic profile having a gradual slope with a full width at half maximum of approximately 170 ?m. The etching rate was approximately 3 ?m/s at an RF power of 1.5 W. The optical emission spectrum exhibited second-positive N2 molecular bands and atomic oxygen lines (777 and 845 nm) as well as many Ar atomic lines. It appears that the energetic N2 molecules and UV photons radiated from the excitation states of N2 broke C-C and C-H bonds and then O radicals reacted with the hydrocarbon fragments to produce CO2 and H2O. Consequently, isotropic chemical etching was achieved.

Yoshiki, Hiroyuki

2010-08-01

241

Localization of Brain-Derived Neurotrophic Factor to Distinct Terminals of Mossy Fiber Axons Implies Regulation of Both Excitation and Feedforward Inhibition of CA3 Pyramidal Cells  

PubMed Central

Hippocampal dentate granule cells directly excite and indirectly inhibit CA3 pyramidal cells via distinct presynaptic terminal specializations of their mossy fiber axons. This mossy fiber pathway contains the highest concentration of brain-derived neurotrophic factor (BDNF) in the CNS, yet whether BDNF is positioned to regulate the excitatory and/or inhibitory pathways is unknown. To localize BDNF, confocal microscopy of green fluorescent protein transgenic mice was combined with BDNF immunohistochemistry. Approximately half of presynaptic granule cell–CA3 pyramidal cell contacts were found to contain BDNF. Moreover, enhanced neuronal activity virtually doubled the percentage of BDNF-immunoreactive terminals contacting CA3 pyramidal cells. To our surprise, BDNF was also found in mossy fiber terminals contacting inhibitory neurons. These studies demonstrate that mossy fiber BDNF is poised to regulate both direct excitatory and indirect feedforward inhibitory inputs to CA3 pyramdal cells and reveal that seizure activity increases the pool of BDNF-expressing granule cell presynaptic terminals contacting CA3 pyramidal cells.

Danzer, Steve C.

2005-01-01

242

Cryogenic exciter  

SciTech Connect

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.

Bray, James William (Niskayuna, NY); Garces, Luis Jose (Niskayuna, NY)

2012-03-13

243

The role of contrast in the perception of achromatic transparency: comment on Singh and Anderson (2002) and Anderson (2003).  

PubMed

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 Michelson contrast should be replaced by perceived contrast in this theory. However, their experimental stimuli were nongeneric (i.e., special cases), and their observers had little choice in their matching strategy. Here, the author shows that both of their ratio-of-contrasts theories are incorrect and that problems with their theoretical analyses and experimental designs led them to conclude that mean luminance does not affect perceived transmittance when contrast is held constant. The author also shows that B. L. Anderson's (2003) transmittance anchoring principle is not valid when a transparent surface is perceived to penetrate rather than overlay another surface. Finally, the author shows that M. Singh's (2004) theoretical proof that the ratio-of-Michelson-contrasts theory accurately predicts lightness matching through transparency is incorrect. PMID:18954224

Albert, Marc K

2008-10-01

244

Localization of Cold Atoms in State-Dependent Optical Lattices via a Rabi Pulse  

SciTech Connect

We propose a novel realization of Anderson localization in nonequilibrium states of ultracold atoms in an optical lattice. A Rabi pulse transfers part of the population to a different internal state with infinite effective mass. These frozen atoms create a quantum superposition of different disorder potentials, localizing the mobile atoms. For weakly interacting mobile atoms, Anderson localization is obtained. The localization length increases with increasing disorder and decreasing interaction strength, contrary to the expectation for equilibrium localization.

Horstmann, Birger; Duerr, Stephan [Max-Planck-Institut fuer Quantenoptik, Hans-Kopfermann-Strasse 1, 85748 Garching (Germany); Roscilde, Tommaso [Laboratoire de Physique, CNRS UMR 5672, Ecole Normale Superieure de Lyon, Universite de Lyon, 46 Allee d'Italie, Lyon, F-69364 (France)

2010-10-15

245

Critical metal phase at the Anderson metal-insulator transition with Kondo impurities  

NASA Astrophysics Data System (ADS)

It is well known that magnetic impurities can change the symmetry class of disordered metallic systems by breaking spin and time-reversal symmetry. At low temperature, these symmetries can be restored by Kondo screening. It is also known that at the Anderson metal-insulator transition, wave functions develop multifractal fluctuations with power-law correlations. Here, we consider the interplay of these two effects. We show that multifractal correlations open local pseudogaps at the Fermi energy at some random positions in space. When dilute magnetic impurities are at these locations, Kondo screening is strongly suppressed. When the exchange coupling J is smaller than a certain value J^*, the metal-insulator transition point extends to a critical region in the disorder strength parameter and to a band of critical states. The width of this critical region increases with a power of the concentration of magnetic impurities. [S. Kettemann, E. R. Mucciolo, and I. Varga, Phys. Rev. Lett. 103, 126401 (2009).

Mucciolo, Eduardo; Kettemann, Stefan; Varga, Imre

2010-03-01

246

Two-Dimensional Graphene with Structural Defects: Elastic Mean Free Path, Minimum Conductivity, and Anderson Transition  

NASA Astrophysics Data System (ADS)

Quantum transport properties of disordered graphene with structural defects (Stone-Wales and divacancies) are investigated using a realistic ?-?* tight-binding model elaborated from ab initio calculations. Mean free paths and semiclassical conductivities are then computed as a function of the nature and density of defects (using an order-N real-space Kubo-Greenwood method). By increasing the defect density, the decay of the semiclassical conductivities is predicted to saturate to a minimum value of 4e2/?h over a large range (plateau) of carrier density (>0.5×1014cm-2). Additionally, strong contributions of quantum interferences suggest that the Anderson localization regime could be experimentally measurable for a defect density as low as 1%.

Lherbier, Aurélien; Dubois, Simon M.-M.; Declerck, Xavier; Roche, Stephan; Niquet, Yann-Michel; Charlier, Jean-Christophe

2011-01-01

247

Area laws in a many-body localized state and its implications for topological order  

NASA Astrophysics Data System (ADS)

The question whether Anderson insulators can persist to finite-strength interactions—a scenario dubbed many-body localization—has recently received a great deal of interest. The origin of such a many-body localized phase has been described as localization in Fock space, a picture we examine numerically. We then formulate a precise sense in which a single energy eigenstate of a Hamiltonian can be adiabatically connected to a state of a non-interacting Anderson insulator. We call such a state a many-body localized state and define a many-body localized phase as one in which almost all states are many-body localized states. We explore the possible consequences of this; the most striking is an area law for the entanglement entropy of almost all excited states in a many-body localized phase. We present the results of numerical calculations for a one-dimensional system of spinless fermions. Our results are consistent with an area law and, by implication, many-body localization for almost all states and almost all regions for weak enough interactions and strong disorder. However, there are rare regions and rare states with much larger entanglement entropies. Furthermore, we study the implications that many-body localization may have for topological phases and self-correcting quantum memories. We find that there are scenarios in which many-body localization can help to stabilize topological order at non-zero energy density, and we propose potentially useful criteria to confirm these scenarios.

Bauer, Bela; Nayak, Chetan

2013-09-01

248

Anderson-Hynes dismembered pyeloplasty performed using the da Vinci robotic system  

Microsoft Academic Search

Introduction. To evaluate and describe the use of the da Vinci robotic system in performing laparoscopic Anderson-Hynes pyeloplasty.Technical Considerations. Between June 2001 and February 2002, 9 patients underwent laparoscopic Anderson-Hynes pyeloplasty with the da Vinci telerobotic surgical system. The diagnosis was based on the presenting symptoms and radiologic imaging findings. The technique for da Vinci-assisted Anderson-Hynes pyeloplasty followed the same

Matthew T Gettman; Richard Neururer; Georg Bartsch; Reinhard Peschel

2002-01-01

249

Wave localization in complex networks with high clustering.  

PubMed

We show that strong clustering of links in complex networks, i.e., a high probability of triadic closure, can induce a localization-delocalization quantum phase transition (Anderson-like transition) of coherent excitations. For example, the propagation of light wave packets between two distant nodes of an optical network (composed of fibers and beam splitters) will be absent if the fraction of closed triangles exceeds a certain threshold. We suggest that such an experiment is feasible with current optics technology. We determine the corresponding phase diagram as a function of clustering coefficient and disorder for scale-free networks of different degree distributions P(k) approximately k;{-lambda}. Without disorder, we observe no phase transition for lambda<4, a quantum transition for lambda>4, and an additional distinct classical transition for lambda>4.5. Disorder reduces the critical clustering coefficient such that phase transitions occur for smaller lambda. PMID:18999764

Jahnke, Lukas; Kantelhardt, Jan W; Berkovits, Richard; Havlin, Shlomo

2008-10-23

250

Quantum resonances in selective rotational excitation of molecules with a sequence of ultrashort laser pulses  

NASA Astrophysics Data System (ADS)

The periodically kicked rotor is a paradigm system for studying classical and quantum chaos. In the quantum regime, the dynamics of the kicked rotor exhibit such phenomena as suppression of classical chaos, Anderson localization in angular momentum and quantum resonances in the accumulation of rotational energy. Even though these effects have been studied with ultracold atoms in optical fields and Rydberg atoms in microwave fields, they have never been observed in a real rotational system. In this work we study the effect of quantum resonance in the rotational excitation of a diatomic molecule. By using femtosecond pulse shaping and rotational state-resolved detection, we measure the rotational distribution of molecules interacting with a train of pulses. We show enhancement of population transfer from the ground to the excited rotational states at resonance, and demonstrate selective rotational excitation of two nitrogen isotopes. We utilize fractional quantum resonances for separating para- and ortho-nitrogen, paving the way to novel methods of coherent control of molecular rotation.

Zhdanovich, Sergey; Bloomquist, Casey; Floss, Johannes; Averbukh, Ilya; Hepburn, John; Milner, Valery

2012-10-01

251

Quantum resonances in selective rotational excitation of molecules with a sequence of ultrashort laser pulses  

NASA Astrophysics Data System (ADS)

The periodically kicked rotor is a paradigm system for studying classical and quantum chaos. In the quantum regime, the dynamics of the kicked rotor exhibit such phenomena as suppression of classical chaos, Anderson localization in angular momentum and quantum resonances in the accumulation of rotational energy. Even though these effects have been studied with ultracold atoms in optical fields and Rydberg atoms in microwave fields, they have never been observed in a real rotational system. In this work we study the effect of quantum resonance in the rotational excitation of a diatomic molecule. By using femtosecond pulse shaping and rotational state-resolved detection, we measure the rotational distribution of molecules interacting with a train of pulses. We show enhancement of population transfer from the ground to the excited rotational states at resonance, and demonstrate selective rotational excitation of two nitrogen isotopes. We utilize fractional quantum resonances for separating para- and ortho-nitrogen, paving the way to novel methods of coherent control of molecular rotation.

Zhdanovich, Sergey; Bloomquist, Casey; Floss, Johannes; Averbukh, Ilya; Hepburn, John; Milner, Valery

2012-06-01

252

Increased peripheral nerve excitability and local NaV1.8 mRNA up-regulation in painful neuropathy  

PubMed Central

Background Neuropathic pain caused by peripheral nerve injury is a chronic disorder that represents a significant clinical challenge because the pathological mechanisms have not been fully elucidated. Several studies have suggested the involvement of various sodium channels, including tetrodotoxin-resistant NaV1.8, in affected dorsal root ganglion (DRG) neurons. We have hypothesized that altered local expression of NaV1.8 in the peripheral axons of DRG neurons could facilitate nociceptive signal generation and propagation after neuropathic injury. Results After unilateral sciatic nerve entrapment injury in rats, compound action potential amplitudes were increased in both myelinated and unmyelinated fibers of the ipsilateral sciatic nerve. Tetrodotoxin resistance of both fiber populations and sciatic nerve NaV1.8 immunoreactivity were also increased. Further analysis of NaV1.8 distribution revealed that immunoreactivity and mRNA levels were decreased and unaffected, respectively, in the ipsilateral L4 and L5 DRG; however sciatic nerve NaV1.8 mRNA showed nearly an 11-fold ipsilateral increase. Nav1.8 mRNA observed in the sciatic nerve was likely of axonal origin since it was not detected in non-neuronal cells cultured from nerve tissue. Absence of changes in NaV1.8 mRNA polyadenylation suggests that increased mRNA stability was not responsible for the selective peripheral mRNA increase. Furthermore, mRNA levels of NaV1.3, NaV1.5, NaV1.6, NaV1.7, and NaV1.9 were not significantly different between ipsilateral and contralateral nerves. We therefore propose that selective NaV1.8 mRNA axonal transport and local up-regulation could contribute to the hyperexcitability of peripheral nerves in some neuropathic pain states. Conclusion Cuff entrapment injury resulted in significantly elevated axonal excitability and increased NaV1.8 immunoreactivity in rat sciatic nerves. The concomitant axonal accumulation of NaV1.8 mRNA may play a role in the pathogenesis of this model of neuropathic pain.

Thakor, Devang Kashyap; Lin, Audrey; Matsuka, Yoshizo; Meyer, Edward M; Ruangsri, Supanigar; Nishimura, Ichiro; Spigelman, Igor

2009-01-01

253

Price-Anderson Nuclear Safety Enforcement Program. 1996 Annual report  

SciTech Connect

This first annual report on DOE`s Price Anderson Amendments Act enforcement program covers the activities, accomplishments, and planning for calendar year 1996. It also includes the infrastructure development activities of 1995. It encompasses the activities of the headquarters` Office of Enforcement in the Office of Environment, Safety and Health (EH) and Investigation and the coordinators and technical advisors in DOE`s Field and Program Offices and other EH Offices. This report includes an overview of the enforcement program; noncompliances, investigations, and enforcement actions; summary of significant enforcement actions; examples where enforcement action was deferred; and changes and improvements to the program.

NONE

1996-01-01

254

Electric dipolar susceptibility of the Anderson-Holstein model  

NASA Astrophysics Data System (ADS)

The temperature dependence of the electric dipolar susceptibility ?P is discussed on the basis of the Anderson-Holstein model with the use of a numerical renormalization group (NRG) technique. Note that ? P is related to the phonon Green's function D. In order to obtain a correct temperature dependence for ? P at low temperatures, we propose a method to evaluate ? P through the Dyson equation from the charge susceptibility ? c calculated by using the NRG instead of the direct NRG calculation of D. We find that the irreducible charge susceptibility estimated from ? c agree with the perturbation calculation, suggesting that our method works well.

Fuse, Takahiro; Hotta, Takashi

2013-06-01

255

Theoretical studies of electronic band-tail states, Anderson transition and surfaces of amorphous semiconductors  

NASA Astrophysics Data System (ADS)

In this dissertation, we study the Anderson transition within the electronic band tail states, and amorphous surfaces. The disorder induced band tail states is one of the unique character of amorphous semiconductors. Because of the proximity to the Fermi level, the nature of these band tail states is of obvious interest to theory of doping and transport. The study of amorphous solid surface is also an interesting area for theory. It is possible to have some major rearrangements near surfaces of amorphous solids (the amorphous analog of surface reconstruction), and the local bonding environment could be dramatically different from that of bulk. The study of the surfaces can also help people toward understanding the growth mechanism. First, electronic band tail states of amorphous silicon and amorphous diamond were studied based on the large (4096 atom) and realistic structural models. To solve the large tight-binding Hamiltonian matrices, we used two order N methods: the maximum entropy method for computing the total densities of states, and the modified Lanczos techniques for computing the individual energy eigenstates in the band gap regions. The DC conductivity was estimated with the Kubo formula. Next, the structural and electronic properties of the surfaces of tetrahedral amorphous carbon (ta-C) were also studied with a first-principles, local basis LDA technique. We reported two structural models made under different conditions, and examined the transition of the local bonding environment from the bulk to the surface. In the study of band tail states, we observe that Anderson (local-to-extended) transition within the band states proceeds by "cluster proliferation". We interpret the nature of band tail states in terms of a "resonant cluster model" through which one can qualitatively understand the evolution of the states from midgap toward the mobility edges. In the study of ta-C surfaces, we observe that nearly 50% surface atoms are threefold coordinated and planar rings or chains are formed with the spsp2 bonds. This "graphization" character also significantly influences its electronic properties. Electrons are easily de-localized within these surface spsp2 rings/chains and some the surface electronic eigenstates become extended along the surface through such rings/chains.

Dong, Jianjun

256

Ferromagnetism in the two-dimensional periodic Anderson model  

SciTech Connect

Using the constrained-path Monte Carlo method, we studied the magnetic properties of the two-dimensional periodic Anderson model for electron fillings between 1/4 and 1/2. We also derived two effective low-energy theories to assist in interpreting the numerical results. For 1/4 filling, we found that the system can be a Mott or a charge-transfer insulator, depending on the relative values of the Coulomb interaction and the charge-transfer gap between the two noninteracting bands. The insulator may be a paramagnet or antiferromagnet. We concentrated on the effect of electron doping on these insulating phases. Upon doping we obtained a partially saturated ferromagnetic phase for low concentrations of conduction electrons. If the system were a charge-transfer insulator, we would find that the ferromagnetism is induced by the well-known Ruderman-Kittel-Kasuya-Yosida interaction. However, we found a novel correlated hopping mechanism inducing the ferromagnetism in the region where the nondoped system is a Mott insulator. Our regions of ferromagnetism spanned a much smaller doping range than suggested by recent slave boson and dynamical mean-field theory calculations, but they were consistent with that obtained by density-matrix renormalization group calculations of the one-dimensional periodic Anderson model.

Batista, C. D.; Bonca, J.; Gubernatis, J. E.

2001-05-01

257

When should cardiologists suspect Anderson-Fabry disease?  

PubMed

Anderson-Fabry disease is a lysosomal storage disorder caused by ?-galactosidase defects and progressive intracellular accumulation of globotriaosylceramide. The disease can be specifically treated with enzyme replacement therapy. Hemizygous men and heterozygous women can develop cardiac disease. Whereas men experience the most severe clinical phenotype, clinical presentation in women varies from asymptomatic to severely symptomatic. The characteristic cardiac phenotype is left ventricular hypertrophy mimicking sarcomeric hypertrophic cardiomyopathy or hypertensive heart disease. Early or prehypertrophy cardiac involvement may escape detection, unless electrocardiographic clues are present. The cardiac markers that raise suspicion of Anderson-Fabry disease include a short PR interval without a ? wave and a prolonged QRS interval, supraventricular and ventricular arrhythmias, and concentric left ventricular hypertrophy. Extracardiac features include renal failure, corneal deposits, and nervous, gastrointestinal, and cutaneous manifestations. Useful family data include cardiac and extracardiac traits in relatives and absence of male-to-male transmission. Symptoms are subtle, and the interval between the onset of symptoms and diagnosis may be as long as 20 years. As such, the diagnosis is typically late. Endomyocardial biopsy shows optically empty myocytes on light microscopy and dense osmiophilic bodies constituted of globotriaosylceramide on electron microscopy. Alpha-galactosidase A activity is reduced in hemizygous men but not in heterozygous women. Genetic testing is the gold standard for the diagnosis. In conclusion, a correct and timely diagnosis offers the possibility of disease-specific treatment that leads to sustained clinical benefits for cardiac and noncardiac signs and symptoms. PMID:21059442

Gambarin, Fabiana I; Disabella, Eliana; Narula, Jagat; Diegoli, Marta; Grasso, Maurizia; Serio, Alessandra; Favalli, B M E Valentina; Agozzino, Manuela; Tavazzi, Luigi; Fraser, Alan G; Arbustini, Eloisa

2010-11-15

258

Applying the Anderson-Darling Test to Suicide Clusters.  

PubMed

Background: Suicide clusters at Cornell University and the Massachusetts Institute of Technology (MIT) prompted popular and expert speculation of suicide contagion. However, some clustering is to be expected in any random process. Aim: This work tested whether suicide clusters at these two universities differed significantly from those expected under a homogeneous Poisson process, in which suicides occur randomly and independently of one another. Method: Suicide dates were collected for MIT and Cornell for 1990-2012. The Anderson-Darling statistic was used to test the goodness-of-fit of the intervals between suicides to distribution expected under the Poisson process. Results: Suicides at MIT were consistent with the homogeneous Poisson process, while those at Cornell showed clustering inconsistent with such a process (p = .05). Conclusions: The Anderson-Darling test provides a statistically powerful means to identify suicide clustering in small samples. Practitioners can use this method to test for clustering in relevant communities. The difference in clustering behavior between the two institutions suggests that more institutions should be studied to determine the prevalence of suicide clustering in universities and its causes. PMID:23502060

Mackenzie, Donald W

2013-03-15

259

Fotoemissao no modelo de Anderson para compostos de terras-raras com valencia flutuante. (Photoemission in the Anderson model for rare earth compounds with floating valences).  

National Technical Information Service (NTIS)

X-ray photoemission spectra (XPS) are calculated for the spin-degenerate Anderson model of valence fluctuation compounds. Based on the renormalization group technique originally introduced by Wilson to calculate the magnetic susceptibility for the Kondo m...

H. O. Frota

1985-01-01

260

Award for Distinguished Scientific Early Career Contributions to Psychology: Adam K. Anderson  

ERIC Educational Resources Information Center

|Adam K. Anderson, recipient of the Award for Distinguished Scientific Early Career Contributions to Psychology, is cited for his outstanding contribution to understanding the representation of emotion and its influence on cognition. By combining psychological and neuroscience techniques with rigorous and creative experimental designs, Anderson

American Psychologist, 2009

2009-01-01

261

Carl V. Anderson oral history interview by Michael Hirsh, September 10, 2008  

Microsoft Academic Search

This is an oral history interviewer with Holocaust concentration camp liberator Carl V. Anderson. Anderson was a sergeant in the 63rd Infantry Division when it liberated Landsberg on April 29, 1945. The division arrived in France in December 1944 and fought in the Battle of the Bulge before proceeding on the Central Europe Campaign. They encountered Landsberg while en route

Carl V. Anderson; Michael Hirsh

2008-01-01

262

Melinda's Closet: Trauma and the Queer Subtext of Laurie Halse Anderson's Speak  

Microsoft Academic Search

Speak, Laurie Halse Anderson’s Michael L. Printz Honor Book, can be read as a coming-out story. The novel tells the story of Melinda Sordino, who, during the summer before her freshman year in high school, is raped at a party by an older boy who goes to the same school Melinda will attend in the fall. After the attack, Melinda,

Don Latham

2007-01-01

263

Comment on Anderson and Cuneo's "The Height + Width Rule in Children's Judgments of Quantity."  

ERIC Educational Resources Information Center

|Bogartz questions the Anderson and Cuneo study (p335-78 of this issue) on statistical-methodological grounds and on their positions concerning the concepts of conservation, centration, and compensation. (For Anderson and Cuneo's rejoinder to Bogartz, see p388-92 of this journal issue.) (SJL)|

Bogartz, Richard S.

1978-01-01

264

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

Federal Register 2010, 2011, 2012, 2013

...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,...

2013-07-12

265

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

PubMed

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

Kleinman, Kim

2013-01-01

266

Price-Anderson Nuclear Safety Enforcement Program. 1997 annual report  

SciTech Connect

This report summarizes activities in the Department of Energy's Price-Anderson Amendments Act (PAAA) Enforcement Program in calendar year 1997 and highlights improvements planned for 1998. The DOE Enforcement Program involves the Office of Enforcement and Investigation in the DOE Headquarters Office of Environment, Safety and Health, as well as numerous PAAA Coordinators and technical advisors in DOE Field and Program Offices. The DOE Enforcement Program issued 13 Notices of Violation (NOV`s) in 1997 for cases involving significant or potentially significant nuclear safety violations. Six of these included civil penalties totaling $440,000. Highlights of these actions include: (1) Brookhaven National Laboratory Radiological Control Violations / Associated Universities, Inc.; (2) Bioassay Program Violations at Mound / EG and G, Inc.; (3) Savannah River Crane Operator Uptake / Westinghouse Savannah River Company; (4) Waste Calciner Worker Uptake / Lockheed-Martin Idaho Technologies Company; and (5) Reactor Scram and Records Destruction at Sandia / Sandia Corporation (Lockheed-Martin).

NONE

1998-01-01

267

Kondo behavior in the asymmetric Anderson model: Analytic approach  

NASA Astrophysics Data System (ADS)

The low-temperature behavior of the asymmetric single-impurity Anderson model is studied by diagrammatic methods resulting in analytically controllable approximations. We first discuss the ways one can simplify parquet equations in critical regions of singularities in the two-particle vertex. The scale vanishing at the critical point defines the Kondo temperature at which the electron-hole correlation function saturates. We show that a two-particle criticality exists at any filling of the impurity level. A quasiparticle resonance peak in the spectral function, however, forms only in almost electron-hole symmetric situations. We relate the Kondo temperature with the width of the resonance peak. Finally, we discuss the existence of satellite Hubbard bands in the spectral function.

Janiš, Václav; Augustinský, Pavel

2008-02-01

268

Effects of band filling in the Anderson-Falicov-Kimball model  

NASA Astrophysics Data System (ADS)

In this work, we study the Anderson-Falicov-Kimball model within the dynamical mean field theory for the Bethe lattice, restricting our analysis to the nonmagnetic case. The one-particle density of states is obtained by both arithmetic and geometric averages over disorder, since only the latter can detect localization in the absence of an energy gap. Varying the strengths of Coulomb interaction and disorder at zero temperature, we construct phase diagrams for this model, where we distinguish spectral regions with localized states, with extended states, or with a correlation-induced gap. With this, we identify metal-insulator transitions driven by correlation and disorder, as well as the competition between these effects. This is done for various band fillings, since our main interest here is to study how the variation of the electron density affects the phase diagrams previously obtained for half-filling. The picture revealed by the density of states is further checked by evaluating the static and dynamic conductivities, including temperature effects.

Carvalho, Rubens D. B.; Gusmão, M. A.

2013-02-01

269

Quantum Group Symmetries of the Anderson Model of a Magnetic Impurity  

NASA Astrophysics Data System (ADS)

The Anderson model of a magnetic impurity is integrable if the local density of states at the impurity site is Lorentzian (width ?). Bethe Ansatz (BA) methods have failed to extract local dynamical properties. The integrable model has huge Yangian ``quantum group symmetries'' not apparent in the BA. Explicitly, the first-quantized expression for the Yangian spin generator that commutes with the Hamiltonian is sumi ?i S_i: ?i = (hi - Ed -U/2)^2 + U sumj ne i ( n_din_dj,h_i - 1/2i? ?_ij?_ij ). Here i labels the electrons, Si is their spin, hi is the one-body kinetic energy and s-d hybridisation, n_di is the projection onto the impurity orbital, and ?_ij = ± 1 or 0 measures the relative order of the particles, d-electrons are at the origin, ?_ij is the exchange operator. When transcribed into second-quantized formalism, a second Yangian ``pseudospin'' generator that completes the full SO(4) symmetry is found. The ground state of the symmetric model is the unique state annihilated by both Yangian generators.

Haldane, F. D. M.

2002-03-01

270

Ground state and excitation properties of the quantum kagom'e system ZnCu3(OH)6Cl2 investigated by local probes.  

NASA Astrophysics Data System (ADS)

We present a comprehensive study on the ground state and excitation spectrum of the S=1/2, analytically pure and perfect kagom'e system ZnCu3% (OH)6Cl2 using the following measurements: magnetization, muon spin rotation frequency shift K, transverse relaxation time T2^*% , and zero field relaxation, and Cl nuclear spin-lattice relaxation T1. Using our data we address four questions which are at the heart of the investigation of the quantum kagom'e system: Do S=1/2 spins on kagom% 'e lattice freeze? Is the ground state magnetic? What is the density of excited states, and is there a gap in the spin energy spectra? Finally, does the lattice distort in order to accommodate spin-Peierls state? We found no sign of singlet formation, no long range order nor spin freezing, and no sign of spin-Peierls transition even at temperatures as low as 60 mK. The density of states has an E^1/4 energy dependence with a negligible magnetic gap to excitation. Thus ZnCu3(OH)6Cl2 is an exotic magnet with no broken continuous symmetry but gapless excitations.

Ofer, Oren; Keren, Amit; Nytko, Emily; Shores, Matthew; Bartlett, Bart; Nocera, Daniel; Amato, Alex; Baines, Chris

2007-03-01

271

Selective ?-bond fission in bromoacetyl chloride upon local excitation at the carbonyl functional group via the n??*(C=O) electronic transition  

Microsoft Academic Search

One of the continuing challenges in chemistry is to develop qualitative understanding and predictive ability for the branching between energetically allowed product chan­ nels. In the area of chemical reaction dynamics, studies of molecular dissociation have proven particularly valuable. For unimolecular dissociation following thermal, infrared multi photon, 1 or overtone excitation 2 in the ground elec­ tronic state, statistical theories

M. D. Person; P. W. Kash; S. A. Schofield; L. J. Butler

1991-01-01

272

Excited upsilon radiative decays  

SciTech Connect

Bottomonium S-wave states were studied using lattice NRQCD. Masses of ground and excited states were calculated using multiexponential fitting to a set of correlation functions constructed using both local and wavefunction-smeared operators. Three-point functions for M1 transitions between vector and pseudoscalar states were computed. Robust signals for transitions involving the first two excited states were obtained. The qualitative features of the transition matrix elements are in agreement with expectations. The calculated values of matrix elements for {Upsilon}(2S) and {Upsilon}(3S) decay are considerably larger than values inferred from measured decay widths.

Lewis, Randy; Woloshyn, R. M. [Department of Physics and Astronomy, York University, Toronto, Ontario, M3J 1P3 (Canada); TRIUMF, 4004 Wesbrook Mall, Vancouver, British Columbia, V6T 2A3 (Canada)

2011-11-01

273

Non-Equilibrium Tunneling Effects of Interacting Hubbard-Anderson Impurities.  

National Technical Information Service (NTIS)

Non-equilibrium interaction effects of Hubbard-Anderson impurities have been experimentally studied by means of STM/STS methods and theoretically analyzed using self-consistent approach based on Keldysh formalism.

P. I. Arseev N. S. Maslova V. I. Panov S. V. Savinov

2001-01-01

274

MD Anderson studies find proton therapy treatment preserves quality of life for men with prostate cancer  

Cancer.gov

Two studies led by The University of Texas MD Anderson Cancer Center have found that proton therapy preserves the quality of life, specifically urinary and bowel function, in men treated with this targeted radiation modality for prostate cancer.

275

MD Anderson study explains high platelets in ovarian cancer patients; survival reduced  

Cancer.gov

Highly elevated platelet levels fuel tumor growth and reduce the survival of ovarian cancer patients, an international team of researchers led by scientists at The University of Texas MD Anderson Cancer center reports in the New England Journal of Medicine.

276

Adaptive Thouless-Anderson-Palmer approach to inverse Ising problems with quenched random fields.  

PubMed

The adaptive Thouless-Anderson-Palmer equation is derived for inverse Ising problems in the presence of quenched random fields. We test the proposed scheme on Sherrington-Kirkpatrick, Hopfield, and random orthogonal models and find that the adaptive Thouless-Anderson-Palmer approach allows accurate inference of quenched random fields whose distribution can be either Gaussian or bimodal. In particular, another competitive method for inferring external fields, namely, the naive mean field method with diagonal weights, is compared and discussed. PMID:23848649

Huang, Haiping; Kabashima, Yoshiyuki

2013-06-19

277

Kondo hole route to incoherence in the periodic Anderson model  

NASA Astrophysics Data System (ADS)

The interplay of disorder and interactions in strongly correlated electronic systems is a subject of perennial interest. In this work, we have investigated the effect of Kondo-hole type disorder on the dynamics and transport properties of heavy fermion systems. We employ the periodic Anderson model within the framework of coherent potential approximation and dynamical mean field theory. The crossover from lattice coherent behaviour to an incoherent single-impurity behaviour is reflected in all aspects: a highly frequency (?)-dependent hybridization becomes almost flat, the coherence peak in resistivity (per impurity) gives way to a Hammann form that saturates at low temperature (T); the Drude peak and the mid-infrared peak in the optical conductivity vanish almost completely. The zero temperature resistivity can be captured in a closed form expression, and we show how the Nordheim's rule gets strongly modified in these systems. The thermopower exhibits a characteristic peak, which changes sign with increasing disorder, and its location is shown to correspond to the low energy scale of the system (?L). In fact, the thermopower appears to be much more sensitive to disorder variations than the resistivity. A comparison to experiments yields quantitative agreement.

Kumar, Pramod; Vidhyadhiraja, N. S.

2013-03-01

278

Band Magnetism in the Two Channel Anderson Lattice Model  

NASA Astrophysics Data System (ADS)

The two channel Anderson Model for uranium ions, comprised of a quadrupolar and a magnetic doublet, exhibits non-Fermi-liquid properties in the paramagnetic phase caused by incoherent spin scattering of a degenerate ground state. It is expected, that the residual entropy will be quenched by a phase transition. The magnetic properties of this model are investigated through the crossover from the Kondo to the weak mixed-valent regime using dynamical mean field theory. A magnetic transition is found in the crossover regime at incommensurable wave vectors. The tendency towards nearest neighbour anti-ferromagnetism is enhanced in the Kondo regime. However, a spin density wave transition, which has an increasing q-vector for a decreasing effective coupling J=V^2/|?_f|, maintains the highest transition temperature T_m. At small coupling, Tm is governed by the RKKY energy scale J^2?(0) in accordance with the Doniach criterion. We report hints to a ferro-magnetic transition in the mixed-valent regime. The origin of the competition between anti-ferromagnetism and spin density waves at small q wave-vectors are discussed. A connection to channel ordering and odd-frequency superconductivity is made. Ref: F.B. Anders, Phys.Rev. Lett., 83, 4638

Anders, Frithjof B. B.

2000-03-01

279

On Diversity of Configurations Generated by Excitable Cellular Automata with Dynamical Excitation Intervals  

NASA Astrophysics Data System (ADS)

Excitable cellular automata with dynamical excitation interval exhibit a wide range of space-time dynamics based on an interplay between propagating excitation patterns which modify excitability of the automaton cells. Such interactions leads to formation of standing domains of excitation, stationary waves and localized excitations. We analyzed morphological and generative diversities of the functions studied and characterized the functions with highest values of the diversities. Amongst other intriguing discoveries we found that upper boundary of excitation interval more significantly affects morphological diversity of configurations generated than lower boundary of the interval does and there is no match between functions which produce configurations of excitation with highest morphological diversity and configurations of interval boundaries with highest morphological diversity. Potential directions of future studies of excitable media with dynamically changing excitability may focus on relations of the automaton model with living excitable media, e.g. neural tissue and muscles, novel materials with memristive properties and networks of conductive polymers.

Adamatzky, Andrew

2012-12-01

280

On the local relaxation of solid neon upon Rydberg excitation of a NO impurity: the role of the NO(A)-Ne interaction potential and zero-point quantum delocalization.  

PubMed

The local relaxation of solid neon subsequent to the impulsive excitation of the NO chromophore to its A(3s sigma) Ryberg state is investigated using molecular dynamics simulations. This study makes use of empirical NO(X,A)-Ne isotropic pair potentials as well as a recently developed ab initio triatomic potential energy surface for the excited state. The role of these interaction potentials is analyzed, including many-body effects. In particular, empirical potentials, designed to reproduce correctly both the NO X-A steady-state absorption and emission bands, are shown to lead to a good description of the subpicosecond relaxation dynamics. The 600 fs expansion of the electronic bubble fairly agrees with experimental data. This relatively long time scale with respect to solid Argon, which was previously attributed to the range of the NO(A)-Ne interaction, is presumably related to the quantum nature of the medium. The time-resolved local relaxation of the Ne solid is understandably intermediate between that of classical solids (e.g., Ar) and that of quantum solids (e.g., H(2)). PMID:19754051

Pajón-Suárez, Pedro; Rojas-Lorenzo, Germán A; Rubayo-Soneira, Jesús; Hernández-Lamoneda, Ramón; Larrégaray, Pascal

2009-12-31

281

Incompleteness of the Thouless, Anderson, and Palmer mean-field description of the spin-glass phase  

NASA Astrophysics Data System (ADS)

We analyze the low-temperature behavior of mean-field equations of Thouless, Anderson, and Palmer (TAP). We demonstrate that degeneracy in free energy makes the low-temperature TAP states unstable. Different solutions of the TAP equations, independent in the TAP approach, become coupled if an infinitesimal interaction between them is introduced. By means of real spin replicas we derive a self-averaging free energy free of unstable states with local magnetizations and homogeneous overlap susceptibilities between different spin replicas as order parameters. We thereby extend the TAP approach to a consistent description of the spin-glass phase for all configurations of spin exchange with (marginally) stable and thermodynamically homogeneous free energy.

Janiš, V.

2006-08-01

282

Applicability of bosonization and the Anderson-Yuval methods at the strong-coupling limit of quantum impurity problems  

NASA Astrophysics Data System (ADS)

The applicability of bosonization and the Anderson-Yuval (AY) approach at strong coupling is investigated by considering two generic impurity models: the interacting resonant-level model and the anisotropic Kondo model. The two methods differ in the renormalization of the conduction-electron density of states (DOS) near the impurity site. Reduction in the DOS, absent in bosonization but accounted for in the AY approach, is shown to be vital in some models yet superfluous in others. The criterion is the stability of the strong-coupling fixed point. Renormalization of the DOS is essential for an unstable fixed point but superfluous when a decoupled entity with local dynamics is formed. This rule can be used to boost the accuracy of both methods at strong coupling.

Borda, L.; Schiller, A.; Zawadowski, A.

2008-11-01

283

Excited Delirium  

PubMed Central

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.

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

2011-01-01

284

Excited baryons  

SciTech Connect

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

Mukhopadhyay, N.C.

1986-01-01

285

Excite's Channels  

NSDL National Science Digital Library

Whatever your opinion about the television-ization of the Internet, channels are coming to a search engine near you. Excite is the latest service to reorganize its content into channels (currently fourteen, from Arts & Entertainment to Travel & Regional). The search interface Excite users have come to know is still available, but many of the other services have been integrated into the channel lineup. NewsTracker, for example (discussed in the February 7, 1997 Scout Report) will show up both in My Channel (a customizable page with content tailored to individual tastes through the magic of cookies) and in the News channel. Users of NewsTracker in its previous incarnation will find their settings still intact when they visit the News channel. Each channel page offers current headlines, Excite services, chat and bulletin boards, and guided web tours, among other resources. If you know exactly what you're looking for, stick to the search interface; if you're in a browsing mood, check out the channels.

286

The dynamics of a harmonically excited system having rigid amplitude constraints. I - Subharmonic motions and local bifurcations. II - Chaotic motions and global bifurcations  

Microsoft Academic Search

An analysis of symmetric double impact motions, both harmonic and subharmonic, is presented. The motions and their stability are determined analytically and local bifurcations are considered. The frequency response curves indicate that there are regions in parameter space for which no stable symmetric orbits with two impacts exist. The motions that can occur in such regions over some open sets

S. W. Shaw

1985-01-01

287

Increased peripheral nerve excitability and local NaV1.8 mRNA up-regulation in painful neuropathy  

Microsoft Academic Search

BACKGROUND: Neuropathic pain caused by peripheral nerve injury is a chronic disorder that represents a significant clinical challenge because the pathological mechanisms have not been fully elucidated. Several studies have suggested the involvement of various sodium channels, including tetrodotoxin-resistant NaV1.8, in affected dorsal root ganglion (DRG) neurons. We have hypothesized that altered local expression of NaV1.8 in the peripheral axons

Devang Kashyap Thakor; Audrey Lin; Yoshizo Matsuka; Edward M Meyer; Supanigar Ruangsri; Ichiro Nishimura; Igor Spigelman

2009-01-01

288

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

NASA Astrophysics Data System (ADS)

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

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

289

Successful salvage therapy with Daptomycin for osteomyelitis caused by methicillin-resistant Staphylococcus aureus in a renal transplant recipient with Fabry-Anderson disease  

PubMed Central

Daptomycin is licensed in adults for the management of Staphylococcus aureus methicillin-resistant infections, including bone and skin complicated infections. We describe for the first time its use in a renal transplant recipient for Fabry-Anderson Disease with right heel osteomyelitis. The patient was unresponsive to first-line Teicoplanin and second-line Tigecycline, whereas he was successfully treated with third-line Daptomycin monotherapy at 4 mg/Kg/qd for 4 weeks. Local debridement was performed in advance of each line of treatment.

2012-01-01

290

Local carrier dynamics around the sub-surface basal-plane stacking faults of GaN studied by spatio-time-resolved cathodoluminescence using a front-excitation-type photoelectron-gun  

NASA Astrophysics Data System (ADS)

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.

Furusawa, K.; Ishikawa, Y.; Tashiro, M.; Hazu, K.; Nagao, S.; Ikeda, H.; Fujito, K.; Chichibu, S. F.

2013-07-01

291

Strong localization of photons in certain disordered dielectric superlattices  

Microsoft Academic Search

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.

Sajeev John

1987-01-01

292

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

USGS Publications Warehouse

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.

Janik, Cathy J.; Goff, Fraser; Walter, S. R.; Sorey, M. L.; Counce, Dale; Colvard, E. M.

2000-01-01

293

Rydberg Excitation of Bose-Einstein Condensates  

SciTech Connect

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

Heidemann, Rolf; Raitzsch, Ulrich; Bendkowsky, Vera; Butscher, Bjoern; Loew, Robert; Pfau, Tilman [5. Physikalisches Institut, Universitaet Stuttgart, Pfaffenwaldring 57, 70569 Stuttgart (Germany)

2008-01-25

294

Rydberg excitation of Bose-Einstein condensates.  

PubMed

Rydberg atoms provide a wide range of possibilities to tailor interactions in a quantum gas. Here, we report on Rydberg excitation of Bose-Einstein condensed 87Rb atoms. The Rydberg fraction was investigated for various excitation times and temperatures above and below the condensation temperature. The excitation is locally blocked by the van der Waals interaction between Rydberg atoms to a density-dependent limit. Therefore, the abrupt change of the thermal atomic density distribution to the characteristic bimodal distribution upon condensation could be observed in the Rydberg fraction. The observed features are reproduced by a simulation based on local collective Rydberg excitations. PMID:18232977

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

2008-01-22

295

Energy-Level and Wave-Function Statistics in the Anderson Model of Localization  

Microsoft Academic Search

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

Bernhard Mehlig; Michael Schreiber

296

Conductivity and magnetoresistance of FeSi in the Anderson-localized regime  

NASA Astrophysics Data System (ADS)

The temperature dependence of the conductivity, ?(T), of FeSi at T ~ 100-170 K follows the Arrhenius law with the value of the band gap Eg ~ 50 +/- 5 meV. Between Tv ~ 15-25 K andT*v ~ 3-4 K it agrees with the Mott-type varriable-range hopping. No tendency of saturation in ?(T) is observed down to 1.4 K. The relative magnetoresistance, ??/?, is negative at T <= 4.2 K and H < 1 T with the amplitude value ~ 0.2%. In higher fields, up to 35 T, it is positive and demonstrates a complex magnetic field and temperature dependence suggesting both positive and negative contributions. At T >= 77 K, ??/? is negligible. The positive component of ??/? agrees with that of the Osaka model which takes into account both correlation and spin-flip effects. The negative contribution is attributed to the Zeeman splitting of the mobility threshold predicted by Kamimura and Kurobe. The temperature dependence of the hopping frequency with the pre-exponent v0 ~ 2.8 × 1012s-1, the value of the internal field,HI ~ 60 kOe, and the maximum value of the correlation energy, Um ~ 17 K, are obtained.

Lisunov, K. G.; Arushanov, E. K.; Kloc, Ch.; Broto, J.; Leotin, J.; Rokoto, H.; Respaud, M.; Bucher, E.

1996-02-01

297

Disorder-enhanced transport in photonic quasi-crystals: Anderson localization and delocalization  

Microsoft Academic Search

We demonstrate experimentally that disorder enhances transport of waves in Penrose-type photonic quasicrystals. Increasing disorder gives rise to a transition from “bumpy ride” to diffusive transport.

Liad Levi; Mikael Rechtsman; Barak Freedman; Tal Schwartz; Ofer Manela; Mordechai Segev

2010-01-01

298

Edge-disorder-induced Anderson localization and conduction gap in graphene nanoribbons  

Microsoft Academic Search

We study the effect of the edge disorder on the conductance of the graphene nanoribbons (GNRs). We find that already very modest edge disorder is sufficient to induce the conduction energy gap in the otherwise metallic GNRs and to lift any difference in the conductance between nanoribbons of different edge geometry. We relate the formation of the conduction gap to

M. Evaldsson; I. V. Zozoulenko; Hengyi Xu; T. Heinzel

2008-01-01

299

Experimental Observation of the Anderson Metal-Insulator Transition with Atomic Matter Waves  

SciTech Connect

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.

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

300

Observation of the Anderson metal-insulator transition with atomic matter waves: Theory and experiment  

SciTech Connect

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.

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

301

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

Code of Federal Regulations, 2010 CFR

...Price-Anderson Act, section 170 of the Atomic Energy Act of 1954. 8.2 Section...Price-Anderson Act, section 170 of the Atomic Energy Act of 1954. (a) It is my...indemnity agreement entered into by the Atomic Energy Commission under the...

2009-01-01

302

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

Code of Federal Regulations, 2010 CFR

...Price-Anderson Act, section 170 of the Atomic Energy Act of 1954. 8.2 Section...Price-Anderson Act, section 170 of the Atomic Energy Act of 1954. (a) It is my...indemnity agreement entered into by the Atomic Energy Commission under the...

2010-01-01

303

Decoherence-induced conductivity in the discrete one-dimensional Anderson model: A novel approach to even-order generalized Lyapunov exponents  

NASA Astrophysics Data System (ADS)

A recently proposed statistical model for the effects of decoherence on electron transport manifests a decoherence-driven transition from quantum-coherent localized to Ohmic behavior when applied to the one-dimensional Anderson model. Here we derive the resistivity in the Ohmic case and show that the transition to localized behavior occurs when the coherence length surpasses a value which only depends on the second-order generalized Lyapunov exponent ?-1. We determine the exact value of ?-1 of an infinite system for arbitrary uncorrelated disorder and electron energy. Likewise all higher even-order generalized Lyapunov exponents can be calculated, as exemplified for fourth order. An approximation for the localization length (inverse standard Lyapunov exponent) is presented, by assuming a log-normal limiting distribution for the dimensionless conductance T. This approximation works well in the limit of weak disorder, with the exception of the band edges and the band center.

Zilly, Matías; Ujsághy, Orsolya; Woelki, Marko; Wolf, Dietrich E.

2012-02-01

304

Politicizing Young Adult Literature: Reading Anderson's "Speak" as a Critical Text.  

ERIC Educational Resources Information Center

Considers how critical texts confront difficult topics. Argues that students need to read, write, and talk about these relevant issues. Suggests that reading literature can be an ethical as well as an intellectual process, and as such it can assist adolescents in coping with their tumultuous lives. Focuses on Laurie Halse Anderson's novel "Speak."…

Alsup, Janet

2003-01-01

305

Suppression of the virtual anderson transition in the impurity band of doped quantum well structures  

NASA Astrophysics Data System (ADS)

We have previously observed activation-type conductivity with low activation energies of heavily doped p-GaAs/AlGaAs quantum well structures at low temperatures. It has been attributed to the delocalization of the electron states near the maximum of a narrow impurity band in the sense of the Anderson transition. The possibility of this delocalization at a relatively low impurity concentration is associated with the narrowness of the impurity band in the presence of weak disorder. In this case, charge carriers were activated from the tail of the band and their presence was due to the background (weak) compensation. In this work, we study the dependence of the above virtual Anderson transition on the external compensation and impurity concentration. It has been found that an increase in the compensation does not initially affect the Anderson transition; however, at a higher compensation, it leads to the suppression of the transition owing to the growing disorder. An increase in the impurity concentration also initially leads to the suppression of the Anderson transition due to the disorder associated with the partial overlap of the Hubbard bands. However, the conductivity becomes metallic at a fairly high concentration due to the Mott transition.

Agrinskaya, N. V.; Kozub, V. I.; Poloskin, D. S.

2011-09-01

306

Adolescent Identities and Sexual Behavior: An Examination of Anderson's Player Hypothesis  

ERIC Educational Resources Information Center

|We investigate the social and behavioral characteristics of male adolescents who self-identify as players, focusing particularly on Anderson's claim that this social role is inextricably linked with poverty and minority status. Results indicate that black respondents, those affiliated with liberal peers and young men who initially report a…

Giordano, Peggy C.; Longmore, Monica A.; Manning, Wendy D.; Northcutt, Miriam J.

2009-01-01

307

MD Anderson-led preclinical research shows normal gene hinders breast cancer chemotherapy  

Cancer.gov

Presence of normal p53, a tumor suppressor gene, instead of a mutated version, makes breast cancer chemotherapy with doxorubicin less effective. The preclinical study led by MD Anderson scientists was published today in the journal Cancer Cell. The research, which challenges the existing paradigm, is another step closer to personalized cancer medicine for breast cancer.

308

The Uses of Practitioner Research and Status Issues in Educational Research: Reply to Gary Anderson.  

ERIC Educational Resources Information Center

Critiques Anderson's response to the theme issue, "Research for Doctoral Students in Education," asserting that questions he raises have few straightforward answers. Agrees that because efforts to study and improve educational practice too often impose abstract findings on school and teachers, it is important to develop a literature based in…

Metz, Mary Haywood; Page, Reba N.

2002-01-01

309

Wildlife Impact Assessment Anderson Ranch, Black Canyon, and Boise Diversion Projects, Idaho. Final Report.  

National Technical Information Service (NTIS)

This report presents an analysis of impacts on wildlife and their habitats as a result of construction and operation of the US Bureau of Reclamation's Anderson Ranch, Black Canyon, and Boise Diversion Projects in Idaho. The objectives were to: (1) determi...

B. Martin K. Ablin-Stone

1986-01-01

310

Community of Inquiry in e-Learning: A Critical Analysis of the Garrison and Anderson Model  

ERIC Educational Resources Information Center

This article is based on a constructively critical analysis of the "community of inquiry" model developed by Garrison and Anderson (2003) as part of their "e-learning" research. The authors claim that certain collaborative interactions create "distant presence" fostering the emergence of a "community of inquiry" which has a positive influence on…

Jezegou, Annie

2010-01-01

311

Approximation of modified Anderson-Darling test statistics for extreme value distributions with unknown shape parameter  

NASA Astrophysics Data System (ADS)

Critical values for the modified Anderson-Darling test statistics are newly derived.Regression equations of test statistics for several distributions were suggested.A power study was performed to compare the efficiency of the goodness-of-fit tests.

Heo, Jun-Haeng; Shin, Hongjoon; Nam, Woosung; Om, Juseong; Jeong, Changsam

2013-08-01

312

4. VIEW OF SITE A FROM ANDERSON WAY, FACING SOUTH/SOUTHWEST. ...  

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

4. VIEW OF SITE A FROM ANDERSON WAY, FACING SOUTH/SOUTHWEST. (BUILDINGS 126, 124, 122, 120, and 114 ARE VISIBLE.) - Fort McPherson, World War II Station Hospital, Structures, Bordered by Hardee & Thorne Avenues & Howe Street, Atlanta, Fulton County, GA

313

On Planetary Evolution and the Evolution of Planetary Science During the Career of Don Anderson  

Microsoft Academic Search

The planets of our solar system have long been viewed by Don Anderson as laboratories for testing general aspects of planetary evolution and as points of comparison to the Earth. I was fortunate to have been a student 39 years ago in a course at Caltech that Don taught with Bob Kovach on the interiors of the Earth and the

S. C. Solomon

2003-01-01

314

Anderson v. University of Wisconsin: Handicap and Race Discrimination in Readmission Procedures.  

ERIC Educational Resources Information Center

"Anderson v. University of Wisconsin" gives important guidance to universities by detailing the components of race and handicap discrimination claims, and illustrating how these claims can succeed. Readmission procedures that could reduce the likelihood of charges of discrimination are suggested. (Author/MLW)

Smith, Elizabeth R.

1989-01-01

315

UT MD Anderson study finds advances in breast cancer don't extend to older women:  

Cancer.gov

The survival rates for older women with breast cancer lag behind younger women diagnosed with the disease, indicating that the elder population may be missing out on improvements in treatment and detection, according to new research from The University of Texas MD Anderson Cancer Center.

316

MD Anderson study finds inflammatory mediator promotes colorectal cancer by stifling protective genes:  

Cancer.gov

Chronic inflammation combines with DNA methylation, a process that shuts down cancer-fighting genes, to promote development of colorectal cancer, scientists at The University of Texas MD Anderson Cancer Center report today in the advance online publication of the journal Nature Medicine.

317

Perturbation approach to the ground state of the asymmetric Anderson model  

NASA Astrophysics Data System (ADS)

The ground state of the asymmetric Anderson model for strong d-electron correlation is investigated by perturbation theory in the s-d mixing integral. The d-level fixed at the Fermi level is shown to be almost unoccupied for ?/D-->0, ?(D) being the d-level (conduction-band) width. The case for moderate ?/D is also discussed.

Inagaki, Satoru

1980-01-01

318

Exact expression of the ground-state energy for the symmetric anderson model  

NASA Astrophysics Data System (ADS)

The exact expression of the ground-state energy for the symmetric Anderson model is obtained with the use of the Wiegmann approach. It is found that some of the quasi-momenta appearing in Wiegmann's paper are necessarily complex to obtain the expression of the ground-state energy.

Kawakami, Norio; Okiji, Ayao

1981-12-01

319

Core-level photoemission spectrum for the spin-degenerate Anderson model  

Microsoft Academic Search

The core-level photoemission for the spin-degenerate single-impurity Anderson model is calculated taking into account the electrostatic interaction of the core hole with the conduction electrons. This interaction changes the spectrum qualitatively and reduces the hybridization between the valence level and the conduction band.

J. J. S. Brito; H. O. Frota

1990-01-01

320

MD Anderson develops prognostic model for MDS related to prior cancer therapy  

Cancer.gov

A large-scale analysis of patients whose myelodysplastic syndrome is related to earlier cancer treatment overturns the notion that all of them have a poor prognosis, researchers from the University of Texas MD Anderson Cancer Center report at the 53rd Annual Meeting of the American Society of Hematology.

321

Finding Order in Chaos: Complexity in the Career of Don L Anderson  

Microsoft Academic Search

Don Anderson's career has been marked by a long standing interest in plate tectonics and the earth's interior. But from time to time, he has departed from these major themes to investigate related topics. For example, during the 1970's, he proposed several seminal ideas, such as the applicability of cracks and fracture theory to earthquakes, and the idea of accelerated

P. Rundle; J. Rundle; W. Klein

2003-01-01

322

MD Anderson-led study finds two targeted therapies act against Ewing's sarcoma tumors  

Cancer.gov

A pair of targeted therapies shrank tumors in some patients with treatment-resistant Ewing's sarcoma or desmoplastic small-round-cell tumors, according to research led by investigators from The University of Texas MD Anderson Cancer Center reported at the American Association for Cancer Research Annual Meeting 2012.

323

Enzyme replacement therapy in Anderson-Fabry's disease: beneficial clinical effect on vital organ function  

Microsoft Academic Search

Two recent randomized trials pointed out the bene- ficial effect of enzyme replacement therapy on bio- chemical parameters in patients with Anderson-Fabry's disease. Clinical end-points, such as amelioration or stabilization of renal function deterioration, or improve- ment of left ventricular hypertrophy have not been evaluated in depth. We report the case of a patient whose moderately impaired renal function was

Dominique Chauveau; Jean-Pierre Grunfeld

324

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

SciTech Connect

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.

Meuleman, G. Allyn

1987-06-01

325

Invasion Waves in Populations with Excitable Dynamics  

Microsoft Academic Search

Whilst the most obvious mechanism for a biological invasion is the occupation of a new territory as a result of direct ingress by individuals of the invading population, a more subtle “invasion” may occur without significant motion of invading individuals if the population dynamics in a predator prey scenario has an “excitable” character. Here, “excitable” means that a local equilibrium

J. Brindley; V. H. Biktashev; M. A. Tsyganov

2005-01-01

326

Localization of a Bose-Fermi mixture in a bichromatic optical lattice  

SciTech Connect

We study the localization of a cigar-shaped superfluid Bose-Fermi mixture in a quasiperiodic bichromatic optical lattice (OL) for interspecies attraction and intraspecies repulsion. The mixture is described by the Gross-Pitaevskii equation for the bosons, coupled to a hydrodynamic mean-field equation for fermions at unitarity. We confirm the existence of the symbiotic localized states in the Bose-Fermi mixture and Anderson localization of the Bose component in the interacting Bose-Fermi mixture on a bichromatic OL. The phase diagram in boson and fermion numbers showing the regions of the symbiotic and Anderson localization of the Bose component is presented. Finally, the stability of symbiotic and Anderson localized states is established under small perturbations.

Cheng Yongshan [Instituto de Fisica Teorica, UNESP - Universidade Estadual Paulista, 01.140-070, Sao Paulo, Sao Paulo (Brazil); Department of Physics, Hubei Normal University, 435002 Huangshi (China); Adhikari, S. K. [Instituto de Fisica Teorica, UNESP - Universidade Estadual Paulista, 01.140-070, Sao Paulo, Sao Paulo (Brazil)

2011-08-15

327

Direct determination of the transition to localization of light in three dimensions  

NASA Astrophysics Data System (ADS)

Diffusive wave transport in three-dimensional media should show a phase transition, with increasing disorder, to a state without transport. This transition was first discussed by Anderson in the context of the metal-insulator transition, but is generic for all waves, as was realized later. However, the quest for the experimental demonstration of `Anderson' localization in three dimensions has been a challenging task. For electrons and cold atoms, the challenge lies in the possibility of bound states in a disordered potential. Therefore, electromagnetic and acoustic waves have been the prime candidates for the observation of Anderson localization. The main challenge in using light lies in the distinction between the effects of absorption and localization. Here, we present measurements of the time dependence of the transverse width of the transmitted-light intensity distribution, which provides a direct measure of the localization length, independent of absorption. This provides direct evidence for a localization transition in three dimensions.

Sperling, T.; Bührer, W.; Aegerter, C. M.; Maret, G.

2013-01-01

328

Plasmonic excitations in nanostructures  

NASA Astrophysics Data System (ADS)

The prevalent classical model of plasmonic calculations for nano-scale metallic clusters is based on the Mie solution. Which consists of solving Maxwell's equations with the material being represented by a dielectric function on its spatial location. However, such a semi-empirical continuum description necessarily breaks down beyond a certain level of coarseness introduced by atomic length scales. Even the bulk based model used for the dielectric function fails by itself. This limitation of the Mie solution has been established by a quantum mechanical calculation with self-consistent treatment of the dielectric response. In order to understand better the plasmonic excitations at nearly atomic scale, we explored the collective electromagnetic response of atomic chains of various sizes and geometries, and we also computed plasmons in graphene in the presence of an impurity. For the atomic chains, we calculated the plasmonic resonances as a function of the system shape, direction of the external applied field, electron filling and atomic separation. Their frequency, oscillator strength and spatial modulation of the induced charge density were analyzed. It was shown that longitudinal and transverse modes can be controlled in amplitude and frequency by the cluster size. It was also observed an abrupt dependence of the modes on the electronic filling. We also find that changes in atomic spacings have a very different impact on low-energy vs. high-energy modes. And it was seen that changing the position of a single atom in a nanostructure can completely alter its collective dielectric response. This strong sensitivity to small changes is the key to controlling the dielectric properties of atomic scale structures, and it can thus become the gateway to a new generation of quantum devices which effectively utilize quantum physics for new functionalities. For graphene it was shown that impurities induce the formation of nanoscale localized plasmonic excitations in graphene sheets. It was studied the dependence of these excitations on the magnitude and size of the impurity potential and electronic filling. It was shown that the impurity potential and doping can be used to tune the properties of nano-plasmonic excitations, demonstrating that graphene is an inherently plasmonic material. It was found that the chemical potential can be used to turn them on and off, but it does not affect their frequency. While their frequency and amplitude can be tuned by varying the strength of the impurity potential. The method employed for this calculation had not been seen before. In principle the results discussed can be tested experimentally by high-frequency optical probes or STM. These results showed that collective excitations in finite systems have properties different from their bulk correspondents. Since there is not a macroscopic number of electrons in the system, the variation of one single electron causes observable differences. The localized resonant modes are very sensitive to even small variations in the system, for example the position of a single atom. This makes it difficult to establish general rules about the properties of collective excitations in atomic structures. On the other hand it also provides a vast range of possibilities that can be explored for achieving new functionalities.

Muniz, Rodrigo Angelo

329

Elementary Excitations and Crossover Phenomenon in Liquids  

NASA Astrophysics Data System (ADS)

The elementary excitations of vibration in solids are phonons. But in liquids phonons are extremely short lived and marginalized. In this Letter through classical and ab initio molecular dynamics simulations of the liquid state of various metallic systems we show that different excitations, the local configurational excitations in the atomic connectivity network, are the elementary excitations in high temperature metallic liquids. We also demonstrate that the competition between the configurational excitations and phonons determines the so-called crossover phenomenon in liquids. These discoveries open the way to the explanation of various complex phenomena in liquids, such as fragility and the rapid increase in viscosity toward the glass transition, in terms of these excitations.

Iwashita, T.; Nicholson, D. M.; Egami, T.

2013-05-01

330

DETERMINATION OF LOCAL MAGNITUDE, ML, FROM STRONG MOTION ACCELEROGRAMS  

Microsoft Academic Search

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

HIROO KANAMORI; PAUL C. JENNINGS

1978-01-01

331

A new local magnitude scale for the Finnish seismic network  

Microsoft Academic Search

A total of 1259 synthesized Wood-Anderson recordings from 216 local and regional earthquakes were used to establish a new ML scale for Finland. The hypocentral distances of the events range from 25 to 1940 km and the reported magnitudes from 1 to 4.The attenuation function (?log A0 in Richter's original definition of ML), magnitudes, and station corrections for the eleven

Marja Uski; Antero Tuppurainen

1996-01-01

332

Temperature and pressure dependence of the Anderson-Grüneisen parameter delta for NaCl crystal  

Microsoft Academic Search

A relation for the temperature dependence of the Anderson-Grüneisen parameter delta has been developed from thermodynamical considerations. It has been shown that Chang's relation (delta=2gamma) is a particular case of this expression. delta has been calculated for rock-salt crystal at different temperatures and pressures and the results have been compared with values of delta computed from the basic equation for

M. N. Sharma; S. Gupta

1975-01-01

333

Transient dynamics and steady state behavior of the Anderson–Holstein model with a superconducting lead  

NASA Astrophysics Data System (ADS)

We analyze the nonequilibrium dynamics and steady-state behavior of the two-terminal Anderson–Holstein model with a superconducting and a normal conducting lead. In the deep Kondo limit we develop an analytical description if no phonons are included and a rate equation approach when phonons are present. Both cases are compared with the numerically exact diagrammatic Monte Carlo method obtaining a good agreement. For small voltages we find a pronounced enhancement of phonon sidebands due to the SC DOS.

Albrecht, K. F.; Soller, H.; Mühlbacher, L.; Komnik, A.

2013-12-01

334

Greek M.D. Anderson Symptom Inventory: Validation and Utility in Cancer Patients  

Microsoft Academic Search

Objective: The M.D. Anderson Symptom Inventory (MDASI) is a brief assessment of the severity and impact of cancer-related symptoms. The purpose of this study was the translation and validation of the questionnaire in Greek (G-MDASI). Methods: The translation and validation of the assessment took place at a Pain Relief and Palliative Care Unit. The final validation sample included 150 cancer

Kyriaki Mystakidou; Charles Cleeland; Eleni Tsilika; Emmanuela Katsouda; Aphrodite Primikiri; Efi Parpa; Lambros Vlahos; Tito Mendoza

2004-01-01

335

K-Sample Anderson-Darling Tests of Fit, for Continuous and Discrete Cases  

Microsoft Academic Search

Two k-sample versions of the Anderson-Darling (AD) test of fit are proposed and their asymptotic null distributions are derived for the continuous as well as the discrete case. In the continuous case the asymptotic distributions coincide with the (k 1)-fold convolution of the 1-sample AD asymptotic distribution. Monte Carlo simulation is used to investigate the null distribution small sample behavior

F. W. Scholz; M. A. Stephens

336

1\\/N expansion of the nonequilibrium single-impurity Anderson Model  

Microsoft Academic Search

Results are presented for the nonequilibrium single-impurity Anderson model using a large-N approach, where N is the degeneracy of the impurity level. Using the Keldysh formalism, we extend the slave-boson functional integral method of Read and Newns to the out of equilibrium current carrying case. The correlation function for the slave boson is shown to exhibit a long time power

Zurab Ratiani; Aditi Mitra

2009-01-01

337

A diagrammatic solution of the single-impurity Anderson model in the Kondo regime  

NASA Astrophysics Data System (ADS)

We study the single-impurity Anderson model with diagrammatic techniques. We employ the parquet approach to determine the electron-hole and electron-electron irreducible vertices self-consistently. We demonstrate that when the dominant contributions from the critical region of the singularity driven by multiple electron-hole scatterings are properly taken into account we make the parquet equations soluble and recover the Kondo asymptotics in the symmetric as well as in the asymmetric cases.

Janiš, V.; Augustinský, P.

2007-06-01

338

Adaptive and self-averaging Thouless-Anderson-Palmer mean-field theory for probabilistic modeling  

Microsoft Academic Search

We develop a generalization of the Thouless-Anderson-Palmer (TAP) mean-field approach of disorder physics, which makes the method applicable to the computation of approximate averages in probabilistic models for real data. In contrast to the conventional TAP approach, where the knowledge of the distribution of couplings between the random variables is required, our method adapts to the concrete set of couplings.

Manfred Opper; Ole Winther

2001-01-01

339

Modified James–Anderson method for stress intensity factors of three-dimensional cracked bodies  

Microsoft Academic Search

James and Anderson have proposed a method for the determination of stress intensity factors for three dimensional cracked bodies from experimentally-measured two-dimensional fatigue crack growth data. In the present work, the method is improved through the use of 3D fatigue crack closure theory, and it is shown that the modified method can accurately evaluate stress intensity factors for 3D cracks.

Haijun Shen; Wanlin Guo

2005-01-01

340

Extracellular matrix turnover and disease severity in Anderson–Fabry disease  

Microsoft Academic Search

Summary  \\u000a Background: Anderson–Fabry Disease (AFD) is an inherited metabolic disease associated with premature death secondary to cardiovascular\\u000a and renal disease. Patients with AFD develop progressive left ventricular (LV) remodelling and heart failure. We hypothesized\\u000a that altered extracellular matrix (ECM) turnover contributes to the pathophysiology of cardiac disease in AFD. Methods and Results: Twenty-nine consecutive patients (44.1 ± 11.7 years, 15

J. S. Shah; D. A. Hughes; M. H. Tayebjee; R. J. MacFadyen; A. B. Mehta; P. M. Elliott

2007-01-01

341

Spin-lattice relaxation rate of a magnetic impurity in the spin degenerate Anderson model  

Microsoft Academic Search

The renormalization group formalism was applied to calculate the spin-lattice\\u000arelaxation rate of a well-defined magnetic moment in the neighborhood of a spin\\u000adegenerate Anderson impurity. In the Kondo regime, the spin-lattice relaxation\\u000arate as a function of the temperature presents a peak at the Kondo temperature;\\u000afor temperature much lower then the Kondo temperature, the system behaves as a

J. W. M. Pinto; H. O. Frota

2004-01-01

342

Esr of a Magnetic Probe in the Neighborhood of AN Anderson Impurity  

Microsoft Academic Search

The renormalization group formalism was applied to calculate the spin lattice relaxation rate T1-1 of a magnetic probe located in the neighborhood of a spin degenerate Anderson impurity. In the Kondo regime, T1-1 as a function of the temperature T presents a peak at the Kondo temperature TK. For T≪TK, the system behaves as a heavy Fermi liquid, with an

J. W. M. Pinto; H. O. Frota

2010-01-01

343

Spin-lattice relaxation rate of a magnetic impurity in the spin degenerate Anderson model  

Microsoft Academic Search

The renormalization group formalism was applied to calculate the spin-lattice relaxation rate of a well-defined magnetic moment in the neighborhood of a spin degenerate Anderson impurity. In the Kondo regime, the spin-lattice relaxation rate as a function of the temperature presents a peak at the Kondo temperature; for temperature much lower then the Kondo temperature, the system behaves as a

J. W. M. Pinto; H. O. Frota

2004-01-01

344

MD Anderson study shows new approach connecting smokers to quit lines increases smoking cessation treatment enrollment  

Cancer.gov

Self-identified smokers directly connected to a tobacco cessation quit line are 13 times more likely to enroll in a treatment program as compared to smokers who are handed a quit line referral card and encouraged to call on their own, according to a new study led by researchers at the University of Texas MD Anderson Cancer Center and published online in JAMA Internal Medicine.

345

Periodic Anderson model with correlated conduction electrons: Variational and exact diagonalization study  

NASA Astrophysics Data System (ADS)

We investigate an extended version of the periodic Anderson model (the so-called periodic Anderson-Hubbard model) with the aim to understand the role of interaction between conduction electrons in the formation of the heavy-fermion and mixed-valence states. Two methods are used: (i) variational calculation with the Gutzwiller wave function optimizing numerically the ground-state energy and (ii) exact diagonalization of the Hamiltonian for short chains. The f-level occupancy and the renormalization factor of the quasiparticles are calculated as a function of the energy of the f orbital for a wide range of the interaction parameters. The results obtained by the two methods are in reasonably good agreement for the periodic Anderson model. The agreement is maintained even when the interaction between band electrons, Ud, is taken into account, except for the half-filled case. This discrepancy can be explained by the difference between the physics of the one- and higher-dimensional models. We find that this interaction shifts and widens the energy range of the bare f level, where heavy-fermion behavior can be observed. For large-enough Ud this range may lie even above the bare conduction band. The Gutzwiller method indicates a robust transition from Kondo insulator to Mott insulator in the half-filled model, while Ud enhances the quasiparticle mass when the filling is close to half filling.

Hagymási, I.; Itai, K.; Sólyom, J.

2012-06-01

346

Admittance of the SU(2) and SU(4) Anderson quantum RC circuits  

NASA Astrophysics Data System (ADS)

We study the Anderson model as a description of the quantum RC circuit for spin-1/2 electrons and a single level connected to a single lead. Our analysis relies on the Fermi liquid nature of the ground state, which fixes the form of the low-energy effective model. The constants of this effective model are extracted from a numerical solution of the Bethe ansatz equations for the Anderson model. They allow us to compute the charge relaxation resistance Rq in different parameter regimes. In the Kondo region, the peak in Rq as a function of the magnetic field is recovered and proven to be in quantitative agreement with previous numerical renormalization group results. In the valence-fluctuation region, the peak in Rq is shown to persist, with a maximum value of h/2e2, and an analytical expression is obtained using perturbation theory. We extend our analysis to the SU(4) Anderson model where we also derive the existence of a giant peak in the charge relaxation resistance.

Filippone, Michele; Le Hur, Karyn; Mora, Christophe

2013-07-01

347

Local transport measurements on epitaxial graphene  

NASA Astrophysics Data System (ADS)

Growth of large-scale graphene is still accompanied by imperfections. By means of a four-tip scanning tunneling and electron microscope (4-tip STM/SEM), the local structure of graphene grown on SiC(0001) was correlated with scanning electron microscope images and spatially resolved transport measurements. The systematic variation of probe spacings and substrate temperature has clearly revealed two-dimensional transport regimes of Anderson localization as well as of diffusive transport. The detailed analysis of the temperature dependent data demonstrates that the local on-top nano-sized contacts do not induce significant strain to the epitaxial graphene films.

Baringhaus, J.; Edler, F.; Neumann, C.; Stampfer, C.; Forti, S.; Starke, U.; Tegenkamp, C.

2013-09-01

348

Light localization in nonuniformly randomized lattices.  

PubMed

We address Anderson localization of light in disordered optical lattices where the disorder strength varies across the transverse direction. Such variation changes the preferred domains where formation of localized eigenmodes is most probable, hence drastically impacting light localization properties. Thus, step-like disorder results in formation of modes with different decay rates at both sides of the interface, while a smoothly varying disorder yields appearance of modes that are extended within weakly disordered domains and rapidly fade away in strongly disordered domains. PMID:22297327

Kartashov, Yaroslav V; Konotop, Vladimir V; Vysloukh, Victor A; Torner, Lluis

2012-02-01

349

Spatiotemporal dynamics of networks of excitable nodes  

NASA Astrophysics Data System (ADS)

A network of excitable nodes based on the photosensitive Belousov-Zhabotinsky reaction is studied in experiments and simulations. The addressable medium allows both local and nonlocal links between the nodes. The initial spread of excitation across the network as well as the asymptotic oscillatory behavior are described. Synchronization of the spatiotemporal dynamics occurs by entrainment to high-frequency network pacemakers formed by excitation loops. Analysis of the asymptotic behavior reveals that the dynamics of the network is governed by a subnetwork selected during the initial transient period.

Steele, Aaron J.; Tinsley, Mark; Showalter, Kenneth

2006-03-01

350

Hydrothermal assembly and luminescence property of lanthanide-containing Anderson polyoxometalates  

SciTech Connect

Two compounds, {l_brace}[Sm(H{sub 2}O){sub 5}]{sub 2}(TeMo{sub 6}O{sub 24}){r_brace}.6H{sub 2}O (1) and {l_brace}[Eu(H{sub 2}O){sub 7}]{sub 2} (TeMo{sub 6}O{sub 24}){r_brace}.5H{sub 2}O (2) have been synthesized by hydrothermal reactions and characterized by elemental analyses, IR spectra, thermal stability analyses, X-ray powder diffraction, and single-crystal X-ray diffraction. Compound 1 represents the first example of a 2D layer architecture constructed from Anderson-type polyoxoanions [TeMo{sub 6}O{sub 24}]{sup 6-} and rare-earth ions Ln{sup 3+}. Compound 2 displays a 1D chain structure built up of alternating Anderson-type polyoxoanions [TeMo{sub 6}O{sub 24}]{sup 6-} and rare-earth ions Eu{sup 3+} along the c-axis. Luminescence measurement of 2 exhibits typical red fluorescent emission of the Eu{sup 3+} ion at room temperature. Furthermore, the emission is intense enough to be observed macroscopically under UV irradiation (365 nm). - Graphical abstract: Two compounds based on Anderson-type polyoxoanion building blocks and rare-earth ions have been synthesized under hydrothermal conditions. Compound 1 exhibits a 2D layer architecture constructed from [TeMo{sub 6}O{sub 24}]{sup 6-} anions and rare-earth ions Ln{sup 3+}. Compound 2 displays a 1D chain structure and possesses the intense luminescence property.

Liu Ying [Key Laboratory of Polyoxometalates Science of Ministry of Education, College of Chemistry, Northeast Normal University, Changchun City, JiLin 130024 (China); Liu Shuxia [Key Laboratory of Polyoxometalates Science of Ministry of Education, College of Chemistry, Northeast Normal University, Changchun City, JiLin 130024 (China)], E-mail: liusx@nenu.edu.cn; Cao Ruige; Ji Hongmei; Zhang Shiwei; Ren Yuanhang [Key Laboratory of Polyoxometalates Science of Ministry of Education, College of Chemistry, Northeast Normal University, Changchun City, JiLin 130024 (China)

2008-09-15

351

Localization in a Quasi-Periodic One Dimensional System  

Microsoft Academic Search

We study mobility edges and Anderson-like localization in a disorder-free, one-dimensional quasi-periodic system. In particular, we study a bichromatic sinusoidal lattice potential where a primary periodic lattice is perturbed by a secondary lattice with a period that is incommensurate with that of the primary lattice. This interesting potential admits both extended and localized states without the presence of disorder. We

John Biddle; Donald Priour; Sankar Das Sarma

2009-01-01

352

Probing localization in absorbing systems via Loschmidt echos.  

PubMed

We measure Anderson localization in quasi-one-dimensional waveguides in the presence of absorption by analyzing the echo dynamics due to small perturbations. We specifically show that the inverse participation number of localized modes dictates the decay of the Loschmidt echo, differing from the Gaussian decay expected for diffusive or chaotic systems. Our theory, based on a random matrix modeling, agrees perfectly with scattering echo measurements on a quasi-one-dimensional microwave cavity filled with randomly distributed scatterers. PMID:19659075

Bodyfelt, Joshua D; Zheng, Mei C; Kottos, Tsampikos; Kuhl, Ulrich; Stöckmann, Hans-Jürgen

2009-06-23

353

Hyperridge of triply excited states  

NASA Astrophysics Data System (ADS)

We present a theory for the definition and the reliable calculation of correlated wave functions of a special class of triply excited states and for their rigorous geometrical analysis. This class is named the three-electron ionization ladder (THEIL) and refers to the simultaneous excitation of three electrons in valence states near threshold. Application to the Li THEIL of 4S ° symmetry reveals impressive localization properties. In analogy with a similar analysis of the ``two-electron ionization ladder,'' which leads smoothly to the so-called ``Wannier ridge'' at the E=0 threshold, the present results suggest the existence of a ``hyperridge'' at E=0 with the following properties: (1) The ion core and the three electrons lie in a plane, (2) ||r1||=||r2||=||r3||, and (3) ?12=?23=?31. .AE

Komninos, Y.; Chrysos, M.; Nicolaides, C. A.

1988-10-01

354

Spatiotemporal control of nanooptical excitations.  

PubMed

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

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

2010-03-08

355

All-solid-state ultrafast lasers facilitate multiphoton excitation fluorescence imaging  

Microsoft Academic Search

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

David L. Wokosin; Victoria Centonze; John G. White; David Armstrong; Gordon Robertson; Allister I. Ferguson

1996-01-01

356

Invariants of the single-impurity Anderson model and implications for conductance functionals  

NASA Astrophysics Data System (ADS)

An exact relation between the conductance maximum G0 at zero temperature and a ratio of lead densities is derived within the framework of the single-impurity Anderson model: G_0={\\mathfrak R}[n] \\frac{2e^2}{h} , where {\\mathfrak R}[n]=4\\Delta N_{{\\cal L},x} \\Delta N_{{\\cal R},x}/(\\Delta N_{{\\cal L},x}+\\Delta N_{{\\cal R},x})^2 and \\Delta N_{{\\cal L},x} , \\Delta N_{{\\cal R},x} denote the excess density in the left/right lead at distance x due to the presence of the impurity at the origin, x = 0. The relation constitutes a parameter-free expression of the conductance of the model in terms of the ground-state density that generalizes an earlier result to the generic case of asymmetric lead couplings. It turns out that the specific density ratio, {\\mathfrak R}[n] , is independent of the distance to the impurity x, the (magnetic) band structure and filling fraction of the contacting wires, the strength of the onsite interaction, the gate voltage and the temperature. Disorder-induced backscattering in the contacting wires has an impact on {\\mathfrak R} that we discuss. Our result suggests that it should be possible, in principle, to determine experimentally the peak conductance of the Anderson impurity by performing a combination of measurements of ground-state densities.

Evers, F.; Schmitteckert, P.

2013-08-01

357

Finding Order in Chaos: Complexity in the Career of Don L Anderson  

NASA Astrophysics Data System (ADS)

Don Anderson's career has been marked by a long standing interest in plate tectonics and the earth's interior. But from time to time, he has departed from these major themes to investigate related topics. For example, during the 1970's, he proposed several seminal ideas, such as the applicability of cracks and fracture theory to earthquakes, and the idea of accelerated plate tectonics. Although on the surface, these topics might seem quite disparate from mantle convection, seismic structure of the earth's interior, and thermodynamics of mineral phases, they nonetheless are now known to share common theoretical underpinnings. In particular, the concepts of nonlinear dynamical systems, complexity, chaos, and energy and fitness landscapes can be used to describe the evolution of all complex nonlinear systems. The principle of minimum free energy (maximum fitness) is frequently used to obtain Langevin-type equations for such systems, and ideas of statistical field theory are employed to obtain scaling exponents and other features. In this talk, we describe these ideas and relate them to the types of problems in which Don Anderson has been primarily interested.

Rundle, P.; Rundle, J.; Klein, W.

2003-12-01

358

Noninvasive determination of local wavespeed and distensibility of the femoral artery by comb-excited Fourier velocity-encoded magnetic resonance imaging: Measurements on athletic and nonathletic human subjects  

Microsoft Academic Search

Summary The local distensibility of arteries is of interest because distensibility varies from artery to artery, may be altered by disease to different extents in different arteries, and may be modified by physiological or pharmacological means. Using magnetic resonance imaging (MRI) we have measured local arterial wavespeed in the femoral artery in healthy human subjects and calculated local arterial distensibility.

Maria Tarnawski; Gerard Cybulski; Denis Doorly; Charles Dumoulin; Robert Darrow; Colin Caro

1994-01-01

359

Excitations Propagating Along Surfaces  

Microsoft Academic Search

A number of equations is deduced which describe propagation of excitations along $n$-dimensional surfaces in $R^N$. Usual excitations in wave theory propagate along 1-dimensional trajectories. The role of the medium of propagation of excitations considered in this paper is played by the infinite dimensional space of $(n-1)$-dimensional surfaces in $R^N$. The role of rays is played by $n$-dimensional solution surfaces

A. V. Stoyanovsky

2003-01-01

360

Patriot Games: Yes, Indeed, the British Are Coming! But M. T. Anderson's Revolutionary War Novel Is Unlike Anything You've Ever Read  

ERIC Educational Resources Information Center

|This article presents an interview with 38-year-old writer Matthew Tobin Anderson. In the interview, Anderson talks about his experiences, passion for writing, teenage interests, and his relation to the distinguished writer Mark Twain. He also states the importance of liberty and what it takes to be a patriot and a loyalist. Furthermore, Matthew…

Horning, Kathleen

2006-01-01

361

Excited state dynamics of phthalocyanine films  

SciTech Connect

Femtosecond pump-probe transient absorption measurements were performed for thermally evaporated polycrystalline vanadyl and lead phthalocyanine (VOPc and PbPc) films in order to obtain information about the excitation energy migration and relaxation. The films were shown to be composed of phase II and amorphous material. Fast excitation localization in phase II was concluded from measurement and analysis of the ground and excited state spectra. Comparison of the ground state, difference absorption, and luminescence spectra suggests a small oscillator strength of the electronic transition from the lowest excited state to the ground state. The influence of local heating on the transient spectra is discussed, and the possibility to obtain the excitation decay kinetics free from this influence is proposed. Exciton-exciton annihilation with a time dependent rate (proportional to t{sup -0.5}) is observed in both films. This is explained by one-dimensional diffusion-limited annihilation. Linear relaxation times are equal to 28{+-}6 and 42{+-}8 ps and approximate intermolecular excitation hopping times of 0.1 divide 0.4 and 0.02 divide 0.08 ps were determined for VOPc and PbPc, respectively. 22 refs., 8 figs., 1 tab.

Gulbians, V.; Valkunas, L. [Vilnius Inst. of Physics (Lithuania); Chachisvillis, M.; Sundstrom, V. [Lund Univ. (Sweden)

1996-02-08

362

Nuclear excitations and reaction mechanisms  

NASA Astrophysics Data System (ADS)

Research concerning nuclear excitations and reaction mechanisms is described. Among the various subjects discussed are: photon scattering, consistency condition between seagull quadrapole terms and the absorption sum rule, Raman scattering to negative-parity states, non-local terms due to exchange and retardation effects in charge-transfer equations, consistency and meaning of various approximate channel coupling array equations, derivation of equations used in empirical nuclear reaction analyses, multi-cluster n-particle scattering theory, converged molecular bound state calculations, and WKB-type approximation in angular momenta for central potentials.

Fallieros, S.; Levin, S. F.; Li, C. T.

1980-10-01

363

Organic photochemistry: Exciting excited-state aromaticity  

NASA Astrophysics Data System (ADS)

In 1972, Baird published rules describing aromaticity and antiaromaticity in the lowest triplet excited states of annulenes. The fortieth anniversary of Baird's rules -- which are the reverse of Hückel's rules for aromaticity and antiaromaticity in the ground state -- ought to be celebrated before 2012 comes to an end.

Ottosson, Henrik

2012-12-01

364

Exciting dark matter in the Galactic Center  

SciTech Connect

We reconsider the proposal of excited dark matter (DM) as an explanation for excess 511 keV gamma rays from positrons in the Galactic center. We quantitatively compute the cross section for DM annihilation to nearby excited states, mediated by exchange of a new light gauge boson with off-diagonal couplings to the DM states. In models where both excited states must be heavy enough to decay into e{sup +}e{sup -} and the ground state, the predicted rate of positron production is never large enough to agree with observations, unless one makes extreme assumptions about the local circular velocity in the Milky Way, or alternatively if there exists a metastable population of DM states which can be excited through a mass gap of less than 650 keV, before decaying into electrons and positrons.

Chen Fang; Cline, James M.; Fradette, Anthony; Frey, Andrew R.; Rabideau, Charles [Physics Department, McGill University, 3600 University Street, Montreal, Quebec, H3A 2T8 (Canada)

2010-02-15

365

Exciting dark matter in the Galactic Center  

NASA Astrophysics Data System (ADS)

We reconsider the proposal of excited dark matter (DM) as an explanation for excess 511 keV gamma rays from positrons in the Galactic center. We quantitatively compute the cross section for DM annihilation to nearby excited states, mediated by exchange of a new light gauge boson with off-diagonal couplings to the DM states. In models where both excited states must be heavy enough to decay into e+e- and the ground state, the predicted rate of positron production is never large enough to agree with observations, unless one makes extreme assumptions about the local circular velocity in the Milky Way, or alternatively if there exists a metastable population of DM states which can be excited through a mass gap of less than 650 keV, before decaying into electrons and positrons.

Chen, Fang; Cline, James M.; Fradette, Anthony; Frey, Andrew R.; Rabideau, Charles

2010-02-01

366

Extraoral maxillofacial prosthetic rehabilitation at the M. D. Anderson Cancer Center: A survey of patient attitudes and opinions  

Microsoft Academic Search

Statement of problem. Measures of satisfaction after extraoral maxillofacial prosthetic rehabilitation have been sparsely reported. Purpose. This article reviews the care-related opinions of patients who were provided extraoral prostheses at the M. D. Anderson Cancer Center over the course of 10 years. Material and methods. A questionnaire was delivered to 263 extraoral prosthetic patients to elucidate their degree of satisfaction

Jeffery C. Markt; James C. Lemon

2001-01-01

367

Identification and Analysis of Learning Preferences of Mentally Ill Adults in Rehabilitative Psychosocial Therapy at the Anderson Mental Health Center.  

ERIC Educational Resources Information Center

|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…

Newman, Michael K.

368

MD Anderson study finds SUMO-snipping protein plays crucial role in T and B cell development  

Cancer.gov

When SUMO grips STAT5, a protein that activates genes, it blocks the healthy embryonic development of immune B cells and T cells unless its nemesis breaks the hold, a research team led by scientists at The University of Texas MD Anderson Cancer Center reports in Molecular Cell.

369

[Comment on ``Mechanical Properties and Processes in the Mantle'' by Sykes, Kay and Anderson] Disagreement With Terms  

Microsoft Academic Search

Attention is invited to the misuse of the word `rheology' by some of your writers. See, for example, `Mechanical Properties and Processes in the Mantle,' by Sykes, Kay, and Anderson, in the December issue of EOS.The word `rheology,' as defined in Dictionary of Geological Terms, Dolphin, 1962, page 423; and Glossary of Geology and Earth Sciences with Supplement, American Geological

J. H. Tatsch

1971-01-01

370

Dynamics of the Anderson model for dilute magnetic alloys: A quantum Monte Carlo and maximum entropy study  

Microsoft Academic Search

In this article we describe the results of a new method for calculating the dynamical properties of the Anderson model. QMC generates data about the Matsubara Green's functions in imaginary time. To obtain dynamical properties, one must analytically continue these data to real time. This is an extremely ill-posed inverse problem similar to the inversion of a Laplace transform from

R. N. Silver; J. E. Gubernatis; D. S. Sivia; M. Jarrell

1990-01-01

371

Cramer–von Mises and Anderson-Darling goodness of fit tests for extreme value distributions with unknown parameters  

Microsoft Academic Search

The use of goodness of fit tests based on Cramer–von Mises and Anderson-Darling statistics is discussed, with reference to the composite hypothesis that a sample of observations comes from a distribution, FH, whose parameters are unspecified. When this is the case, the critical region of the test has to be redetermined for each hypothetical distribution FH. To avoid this difficulty,

Francesco Laio

2004-01-01

372

Survival and recurrence factors in adult medulloblastoma: The M.D. Anderson Cancer Center experience from 1978 to 1998  

Microsoft Academic Search

Medulloblastoma is a rare adult primary brain tumor for which limited retrospective studies are available to elucidate natural history or to guide therapy. A retro- spective chart and imaging review of adult patients (aged >18 years) with medulloblastoma was performed to identify survival and prognostic factors. Fifty-seven patients were evaluated at the University of Texas M.D. Anderson Cancer Center from

Lara J. Kunschner; John Kuttesch; Kenneth Hess; W. K. Alfred Yung

373

Hydromagnetic waves excited during an ssc  

Microsoft Academic Search

The effects of hydromagnetic perturbations that were excited by an ssc were seen at L = 8.2, - 12 ø geomagnetic latitude, 0610 geomagnetic local time in Explorer 12 energetic particle and magnetic field data, and on ground magnetograms. The entire day side magnetosphere was compressed by 2-3 RE in 2-3 min. This compression and the accompanying increase in magnetopause

Richard L. Kaufmann; David N. Walker

1974-01-01

374

Route to strong localization of light: the role of disorder.  

PubMed

By employing Random Matrix Theory (RMT) and first-principle calculations, we investigated the behavior of Anderson localization in 1D, 2D and 3D systems characterized by a varying disorder. In particular, we considered random binary layer sequences in 1D and structurally disordered photonic crystals in two and three dimensions. We demonstrated the existence of a unique optimal degree of disorder that yields the strongest localization possible. In this regime, localized modes are constituted by defect states, which can show subwavelength confinement properties. These results suggest that disorder offers a new avenue for subwavelength light localization in purely dielectric media. PMID:23038363

Molinari, Diego; Fratalocchi, Andrea

2012-07-30

375

Hubbard physics in the symmetric half-filled periodic anderson-hubbard model  

NASA Astrophysics Data System (ADS)

Two very different methods — exact diagonalization on finite chains and a variational method — are used to study the possibility of a metal-insulator transition in the symmetric half-filled periodic Anderson-Hubbard model. With this aim we calculate the density of doubly occupied d sites ( gn d ) as a function of various parameters. In the absence of on-site Coulomb interaction ( U f ) between f electrons, the two methods yield similar results. The double occupancy of d levels remains always finite just as in the one-dimensional Hubbard model. Exact diagonalization on finite chains gives the same result for finite U f , while the Gutzwiller method leads to a Brinkman-Rice transition at a critical value ( U {/d c }), which depends on U f and V.

Hagymási, I.; Itai, K.; Sólyom, J.

2013-05-01

376

Extended recursion in operator space (EROS), a new impurity solver for the single impurity Anderson model  

SciTech Connect

We have developed a new efficient and accurate impurity solver for the single impurity Anderson model (SIAM), which is based on a non-perturbative recursion technique in a space of operators and involves expanding the self-energy as a continued fraction. The method has no special occupation number or temperature restrictions; the only approximation is the number of levels of the continued fraction retained in the expansion. We also show how this approach can be used as a new approach to Dynamical Mean Field Theory (DMTF) and illustrate this with the Hubbard model. The three lowest orders of recursion give the Hartree-Fock, Hubbard I, and Hubbard III approximations. A higher level of recursion is able to reproduce the expected 3-peak structure in the spectral function and Fermi liquid behavior.

Albers, Robert C [Los Alamos National Laboratory; Julien, Jean P [Los Alamos National Laboratory

2008-01-01

377

Hydrothermal synthesis of two Anderson POM-supported transition metal organic–inorganic compounds  

Microsoft Academic Search

Two isostructural compounds based on Anderson polyoxoanions, [Cu(phen)]2[CrMo6H5O24] (1) and [Cu(phen)]2[AlMo6H5O24] (2) (phen=1,10-phenaanthroline), have been hydrothermally synthesized and characterized by IR, XPS, EPR spectra, TG analyses, magnetic susceptibility, and single-crystal X-ray diffraction. Compounds crystallize in the monoclinic space group P2(1)\\/n with a=5.66710(10)Å, b=21.3723(5)Å, c=14.7092(3)Å, ?=98.10(10)°, V=1763.79(6)Å3, R1=0.0240, Z=2 and GOF=1.140 for 1, and in the monoclinic space group P2(1)\\/n with

Hui-yuan Ma; Li-zhou Wu; Hai-jun Pang; Xin Meng; Jun Peng

2010-01-01

378

New supramolecular hybrids based on A-type Anderson polyoxometalates and Mn–Schiff-base complexes  

Microsoft Academic Search

By combination of metal–Schiff-base complexes and A-type Anderson heteropolymolybdates, two new metal–Schiff-base polyoxometalate hybrid compounds [Mn(salen)(H2O)2]2Na3[IMo6O24]·18H2O (1) and [Mn(salpn)(H2O)2]2Na3[IMo6O24]·10H2O (2) (salen=N,N?-ethylene-bis(salicylideneiminate) and salpn=N,N?-(1,3-propylene)bis(salicylideneiminate)) have been successfully isolated. Compounds 1 and 2 were characterized by the single crystal X-ray diffraction analysis, elemental analysis, IR spectroscopy, TG analyses and XPS spectra. Single-crystal X-ray diffraction analysis revealed that both compounds exhibit 3-D supramolecular

Qiong Wu; Shi-Wei Lin; Yang-Guang Li; En-Bo Wang

379

Backbone structure of the Edwards-Anderson spin-glass model  

NASA Astrophysics Data System (ADS)

We study the ground-state spatial heterogeneities of the Edwards-Anderson spin-glass model with both bimodal and Gaussian bond distributions. We characterize these heterogeneities by using a general definition of bond rigidity, which allows us to classify the bonds of the system into two sets, the backbone and its complement, with very different properties. This generalizes to continuous distributions of bonds the well-known definition of a backbone for discrete bond distributions. By extensive numerical simulations we find that the topological structure of the backbone for a given lattice dimensionality is very similar for both discrete and continuous bond distributions. We then analyze how these heterogeneities influence the equilibrium properties at finite temperature and we discuss the possibility that a suitable backbone picture can be relevant to describe spin-glass phenomena.

Romá, F.; Risau-Gusman, S.

2013-10-01

380

Decay of a nonlinear impurity in a structured continuum from a nonlinear Fano-Anderson model  

SciTech Connect

The decay dynamics of a nonlinear impurity mode embedded in a linear structured continuum is theoretically investigated in the framework of a nonlinear Fano-Anderson model. A gradient flow dynamics for the survival probability is derived in the Van Hove ({lambda}{sup 2}t) limit by a multiple-scale asymptotic analysis, and the role of nonlinearity on the decay law is discussed. In particular, it is shown that the existence of bound states embedded in the continuum acts as transient trapping states which slow down the decay. The dynamical behavior predicted in the {lambda}{sup 2}t limit is studied in detail for a simple tight-binding one-dimensional lattice model, which may describe electron or photon transport in condensed matter or photonic systems. Numerical simulations of the underlying equations confirm, in particular, the trapping effect in the decay process due to bound states embedded in the continuum.

Longhi, Stefano [Dipartimento di Fisica and Istituto di Fotonica e Nanotecnologie del CNR, Politecnico di Milano, Piazza Leonardo da Vinci 32, I-20133 Milan (Italy)

2007-05-01

381

The Ce 4{ital f} surface shift: A test for the Anderson-impurity Hamiltonian  

SciTech Connect

Evidence is provided of the role of the different hybridization strengths between the surface and the bulk in determining the magnitude of the surface shift for the shallow Ce 4{ital f} levels, with respect to the deeper core levels. This was achieved by comparing the photoemission core levels for a weakly hybridized case (CeAl) to a case of intermediate hybridization ({gamma}-Ce). For CeAl a 4{ital f} surface shift of 0.45 eV was observed, similar to that for the 5{ital p} core level, whereas a smaller (if any) 4{ital f} surface shift was observed for {gamma}-Ce. Model calculations based on the Anderson impurity Hamiltonian are shown to give a correct evaluation of this effect, which can be exploited as a way of testing the results of such a description for the Ce {ital f} states. {copyright} {ital 1996 The American Physical Society.}

Duo, L.; De Rossi, S.; Vavassori, P.; Ciccacci, F. [Istituto Nazionale Fisica della Materia--Dipartimento di Fisica, Politecnico di Milano, piazza Leonardo da Vinci 32, I-20133 Milano (Italy); Olcese, G.L. [Dipartimento di Chimica e Chimica Industriale, Universita di Genova, via Dodecaneso 31, I-16146 Genova (Italy); Chiaia, G.; Lindau, I. [Department of Synchrotron Radiation Research, Lund University, Soelvegatan 14, S-22362 Lund (Sweden)

1996-12-01

382

1/( N - 1) expansion approach to full-counting statistics for the SU( N) Anderson model  

NASA Astrophysics Data System (ADS)

We apply a recently developed 1/( N - 1) expansion to the full-counting statistics for the N-fold degenerate Anderson impurity model in the Kondo regime. This approach is based on the perturbation theory in the Coulomb interaction U and is different from the conventional large- N theories, such as the usual 1/ N expansion and non-crossing approximation. We have confirmed that the calculations carried out up to order 1/( N - 1)2 agree closely with those of the numerical renormalization group at N = 4, where the degeneracy is still not so large. This ensures the applicability of our approach for N ? 4. We present the results of the cumulants of the probability distribution function for a nonequilibrium current through a quantum dot in the particle-hole symmetric case.

Oguri, Akira; Sakano, Rui

2013-08-01

383

Fermi surface reconstruction in the Kondo lattice model and the periodic Anderson model  

NASA Astrophysics Data System (ADS)

We study the ground state properties of the Kondo lattice model (KLM) and the periodic Anderson model (PAM) in a two-dimensional square lattice with the variational Monte Carlo method. In addition to the conventional second-order antiferromagnetic transition, we find a novel type of quantum phase transition which induces the change of topology of the Fermi surface (Fermi surface reconstruction). The Fermi surface reconstruction is originated from the mechanism of the energy gain and is characteristic both of the KLM and of the PAM. We show the ground state phase diagrams of both models and discuss the relation to the recent experiments which have investigated the change of the Fermi surface.

Watanabe, Hiroshi; Ogata, Masao

2009-03-01

384

High-energy neutron dosimetry at the Clinton P. Anderson Meson Physics Facility  

SciTech Connect

Neutron energy spectrum measurements performed at the Clinton P. Anderson Meson Physics Facility indicated potential areas for high energy neutron exposure to personnel. The low sensitivity of the Los Alamos thermoluminescent dosimeter (TLD) to high energy neutrons warranted issuing a NTA dosimeter in addition to the TLD badge to employees entering these areas. The dosimeter consists of a plastic holder surrounding NTA film that has been desiccated and sealed in a dry nitrogen environment. A study of the fading of latent images in NTA film demonstrated the success of this packaging method to control the phenomenon. The Los Alamos NTA dosimeter is characterized and the fading study discussed. 10 refs., 4 figs., 2 tabs.

Mallett, M.W.; Vasilik, D.G.; Littlejohn, G.J.; Cortez, J.R.

1990-01-01

385

ARPES in strongly correlated 4f and 5f systems: Comparison to the Periodic Anderson Model  

SciTech Connect

The electronic structure of both Ce and U heavy fermions appears to consist of extremely narrow, nearly temperature independent bands (i.e., no spectral weight loss or transfer with temperature). A small dispersion of the f-bands above the Kondo temperature is easily measurable so that a Kondo resonance, as defined by NCA, is not evident. Preliminary results, however, indicate that the Periodic Anderson Model captures some of the essential physics. Angle-integrated resonant photoemission results on {delta}-Pu indicate a narrow 5f feature at E{sub F}, similar in width to f-states in Ce and U compounds, but differing in that cross-section behavior of the near-E{sub F} feature suggests substantial 6D admixture.

Arko, A.J.; Joyce, J.J.; Cox, L.E. [and others

1997-12-01

386

Transport across an Anderson quantum dot in the intermediate coupling regime  

NASA Astrophysics Data System (ADS)

We describe linear and nonlinear transport across a strongly interacting single impurity Anderson model quantum dot with intermediate coupling to the leads, i.e. with tunnel coupling ? of the order of the thermal energy kBT. The coupling is large enough that sequential tunneling processes (second order in the tunneling Hamiltonian) alone do not suffice to properly describe the transport characteristics. Upon applying a density matrix approach, the current is expressed in terms of rates obtained by considering a very small class of diagrams which dress the sequential tunneling processes by charge fluctuations. We call this the "dressed second order" (DSO) approximation. One advantage of the DSO is that, still in the Coulomb blockade regime, it can describe the crossover from thermally broadened to tunneling broadened conductance peaks. When the temperature is decreased even further (kBT < ?), the DSO captures Kondesque behaviours of the Anderson quantum dot qualitatively: we find a zero bias anomaly of the differential conductance versus applied bias, an enhancement of the conductance with decreasing temperature as well as universality of the shape of the conductance as function of the temperature. We can without complications address the case of a spin degenerate level split energetically by a magnetic field. In case spin dependent chemical potentials are assumed and only one of the four chemical potentials is varied, the DSO yields in principle only one resonance. This seems to be in agreement with experiments with pseudo spin [U. Wilhelm, J. Schmid, J. Weis, K.V. Klitzing, Physica E 14, 385 (2002)]. Furthermore, we get qualitative agreement with experimental data showing a cross-over from the Kondo to the empty orbital regime.

Kern, Johannes; Grifoni, Milena

2013-09-01

387

Excitation of spin waves by an electric current  

Microsoft Academic Search

The excitation of spin waves in an unbounded ferromagnetic film by a direct spin-polarized current distributed over a small area is treated macroscopically. The derived critical threshold current for excitation has two additive terms: The first arises from radiation of spin waves and is constant. The second arises from local viscous dissipation and varies in proportion to damping coefficient, external

J. C Slonczewski

1999-01-01

388

Ultrasound excited thermography - advances due to frequency modulated elastic waves  

Microsoft Academic Search

Ultrasound excited thermography allows for defect selective imaging using thermal waves that are generated by elastic waves. The mechanism involved is local friction or hysteresis which turns a dynamically loaded defect into a heat source which is identified by a thermography system. If the excitation frequency matches to a resonance of the vibrating system, temperature patterns can occur that are

Thomas Zweschper; Gernot Riegert; A. Dillenz; Gerd Busse

2005-01-01

389

Approximation of effective lifetimes for spatially nonuniform excitation of atoms  

Microsoft Academic Search

This paper analyzes the error of the Biberman approximation and interprets results obtained when the zone of primary excitation of atoms is localized inside gaseous media. This occurs during the contraction of a discharge column or during the excitation of atoms by a narrow beam of high-speed particles (electrons, protons, photons). The authors consider a volume of gas in the

N. N. Bezuglov; A. N. Klyucharev

1986-01-01

390

Excited Charm States  

SciTech Connect

Characteristics of mass spectra and decays of orbitally excited charm mesons and baryons, expected on the basis of quark models and Heavy Quark Symmetry, are briefly described. The difficulties associated with measurements on these excited states are discussed. The accuracy and reliability of currently available experimental information is examined. The reasons, for the widely accepted spin-parity assignments to the observed excited mesons and baryons, are stated. Finally, the experimental data, with the accepted spin-parity assignments, is compared with expectations based on quark models and Heavy Quark Symmetry.

Shukla, S.

1994-12-31

391

Molecular excitation in sprites  

Microsoft Academic Search

We have determined the molecular internal energy distribution in the N2 B³IIg state from the fluorescence measured during the observations of sprites during 1995. Spectrally resolved data from two different instruments and three different sprites are compared with theoretical spectra to obtain excited state vibrational distributions. Energy dependent electron excitation cross-sections and laboratory data were used to estimate the energies

B. D. Green; M. E. Fraser; W. T. Rawlins; L. Jeong; W. A. M. Blumberg; S. B. Mende; G. R. Swenson; D. L. Hampton; E. M. Wescott; D. D. Sentman

1996-01-01

392

Molecular excitation in sprites  

Microsoft Academic Search

We have determined the molecular internal energy distribution in the N2 B3Pig state from the fluorescence measured during the observations of sprites during 1995. Spectrally resolved data from two different instruments and three different sprites are compared with theoretical spectra to obtain excited state vibrational distributions. Energy dependent electron excitation cross-sections and laboratory data were used to estimate the energies

B. D. Green; M. E. Fraser; W. T. Rawlins; L. Jeong; W. A. M. Blumberg; S. B. Mende; G. R. Swenson; D. L. Hampton; E. M. Wescott; D. D. Sentman

1996-01-01

393

Nuclear Excitation by Electronic Processes: NEEC and NEET Effects  

SciTech Connect

The nuclear excitation by electron capture (NEEC) and nuclear excitation by electronic transition (NEET), and related de-excitation, are two important electromagnetic processes to modify the nuclear state populations. In this paper, we present, on one hand, an experiment accepted at GANIL (France) in September 2004 to measure the NEEC effect with a fully stripped 57Fe ion beam and, on the other hand, a complete calculation leading to the NEET rate of the first excited state of the 235U in a local thermodynamic equilibrium (LTE) plasma.

Morel, P.; Daugas, J.M.; Gosselin, G.; Meot, V.; Gogny, D. [Commissariat a l'Energie Atomique, DIF/DPTA/Service de Physique Nucleaire, BP12, 91680 Bruyeres-le-Chatel (France)

2005-05-24

394

Fermi-surface and charge-spin excitations in strongly correlated electron systems  

SciTech Connect

Fermi-surface and low-energy excitations in a variety of strongly correlated electron systems are studied by using the numerically exact diagonalization method in two-dimensional square lattice. In the one-band Hubbard and extended Hubbard models, the electronic structure in both insulating and metallic states are examined. The structure in the periodic Anderson model is also studied and compared with that in the above models. In the tJ model as well as the negative U Hubbard model, the excitation spectra in the superconducting states are calculated. In particular, in the tJ model the superconductivity with d(x{sup 2}-y{sup 2})-wave pairing is found to be mapped onto the BCS state. It is shown that the systematic study in a variety of models provides an opportunity to construct a unified picture of strongly correlated systems.

Maekawa, S. [Nagoya Univ. (Japan)

1995-05-01

395

Singlet-triplet Hamiltonian for spin excitations in a Kondo insulator  

SciTech Connect

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.

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

396

Wait! Don't Turn That Dial! More Excitement to Come! The Effects of Story Length and Production Pacing in Local Television News on Channel Changing Behavior and Information Processing in a Free Choice Environment  

Microsoft Academic Search

This article investigates whether news story length and production pac- ing affect channel changing behavior in younger and older adults. Viewers used a remote control device to choose among four local news programs that varied systematically by story length and pacing. In gen- eral, pacing and length have greater effects on younger viewers. Fast pacing increased viewers' evaluations of the

Annie Lang; Mija Shin; Samuel D. Bradley; Zheng Wang; Seungjo Lee; Deborah Potter

2005-01-01

397

Testing the excitability of human motoneurons  

PubMed Central

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.

McNeil, Chris J.; Butler, Jane E.; Taylor, Janet L.; Gandevia, Simon C.

2013-01-01

398

Excitation of waves in an inhomogeneous plasma  

SciTech Connect

The evolution of initial perturbations in a spatially inhomogeneous cold electron plasma in the absence of an external magnetic field is considered. The excitation of both continuous-spectrum bulk plasma waves and surface plasma waves with a discrete frequency spectrum is investigated. Analytic solutions are obtained in the long-wavelength limit, and the excitation of waves of arbitrary length is analyzed numerically. The local, integral, and spatial spectra are calculated, as well as the field structures and dispersion properties of waves in waveguides filled nonuniformly with a plasma. It is shown that, in a plasma with a smooth boundary, there also exist surface waves with a discrete spectrum (although with somewhat different properties as compared to those in a plasma with a sharp boundary), which are excited together with continuous-spectrum bulk waves during the evolution of the initial perturbation.

Kuzelev, M. V. [Moscow State University (Russian Federation)

2008-06-15

399

Extending the Newns-Anderson model to allow nanotransport studies through molecules with floppy degrees of freedom  

NASA Astrophysics Data System (ADS)

The Newns-Anderson model is ubiquitous in studies of the molecular transport in the presence of solvent (outer) reorganization. The present work demonstrates that intramolecular reorganization can also be significant for the transport through molecules with floppy degrees of freedom, for which the Newns-Anderson model can be extended. The expressions of the model parameters deduced from electronic structure calculations for (4, 4')-bipyridine (44BPY) quantitatively differ from those characteristic for outer reorganization due to strong intramolecular anharmonicities. These expressions can be utilized as input in transport calculations for 44BPY-based molecular junctions of experimental interest (Xu B. and Tao N. J., Science, 301 (2003) 1221; Pobelov I. V. et al., J. Am. Chem. Soc., 130 (2008) 16045; Widawsky J. R. et al., Nano Lett., 12 (2012) 354).

Bâldea, Ioan

2012-08-01

400

Phase relaxation in slowly changing environments: Evaluation of the Kubo-Anderson model for a continuous-time random walk  

NASA Astrophysics Data System (ADS)

The Kubo-Anderson model is a stochastic model of phase relaxation of an ensemble of systems in a fluctuating environment. This model is usually studied under the assumption that the system-environment interaction is a Gaussian stochastic process. This assumption only holds if the environment changes a very large number of times on the time scale of the system's motion. This paper reviews our work on the Kubo-Anderson model for the case where this interaction is a continuous-time random walk. A continuous-time random walk is a simple model for a `slowly changing environment', i.e., one which makes a relatively small number of changes on the time scale of the system's motion. We present the key results from this model and show how to apply them to common problems in magnetic resonance spectroscopy and and non-linear optical spectroscopy.

Packwood, Daniel M.

2013-02-01

401

Excitation Methods for Bridge Structures  

SciTech Connect

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

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

1999-02-08

402

An overview of the comprehensive proton therapy machine quality assurance procedures implemented at The University of Texas M. D. Anderson Cancer Center Proton Therapy Center-Houston  

SciTech Connect

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.

Arjomandy, Bijan; Sahoo, Narayan; Zhu, X. Ronald; Zullo, John R.; Wu, Richard Y.; Zhu Mingping; Ding Xiaoning; Martin, Craig; Ciangaru, George; Gillin, Michael T. [Department of Radiation Physics, University of Texas M. D. Anderson Cancer Center, 1840 Old Spanish Trail, Houston, Texas 77025 (United States)

2009-06-15

403

Anderson-Fabry disease: clinical manifestations and impact of disease in a cohort of 60 obligate carrier females  

Microsoft Academic Search

EDITOR—Anderson-Fabry disease (AFD) is a sphingolipid storage disorder resulting from the deficiency of the lysosomal enzyme Æ-galactosidase. Unlike most other lysosomal diseases, the inheritance is X linked. Disease manifestations in female heterozygotes have been reported, but are considered to be rare and usually mild. 1 Asymptomatic corneal dystrophy (cornea verticillata and posterior lenticular cataract) is present in about 70% and

K D MacDermot; A Holmes; A H Miners

2001-01-01

404

Babies, Child Bearers and Commodification: Anderson, Brazier et al., and the Political Economy of Commercial Surrogate Motherhood  

Microsoft Academic Search

It is argued by Anderson and also in the BrazierReport that Commercial Surrogate Motherhood (C.S.M.)contracts and agencies should be illegal on thegrounds that C.S.M. involves the commodification ofboth mothers and babies. This paper takes issue withthis view and argues that C.S.M. is not inconsistentwith the proper respect for, and treatment of,children and women. A case for the legalisation ofC.S.M. is

Hugh V. McLachlan; J. K. Swales

2000-01-01

405

Babies, child bearers and commodification: Anderson, Brazier et al., and the political economy of commercial surrogate motherhood.  

PubMed

It is argued by Anderson and also in the Brazier Report that Commercial Surrogate Motherhood (C.S.M.) contracts and agencies should be illegal on the grounds that C.S.M. involves the commodification of both mothers and babies. This paper takes issue with this view and argues that C.S.M. is not inconsistent with the proper respect for, and treatment of, children and women. A case for the legalization of C.S.M. is made. PMID:10977156

McLachlan, H V; Swales, J K

2000-01-01

406

Relaxational dynamics of the Edwards-Anderson model and the mean-field theory of spin-glasses  

Microsoft Academic Search

Langevin equations for the relaxation of spin fluctuations in a soft-spin version of the Edwards-Anderson model are used as a starting point for the study of the dynamic and static properties of spin-glasses. An exact uniform Lagrangian for the average dynamic correlation and response functions is derived for arbitrary range of random exchange, using a functional-integral method proposed by De

H. Sompolinsky; Annette Zippelius

1982-01-01

407

Nailing the Coffin Shut on Doubts That Violent Video Games Stimulate Aggression: Comment on Anderson et al. (2010)  

Microsoft Academic Search

Over the past half century the mass media, including video games, have become important socializers of children. Observational learning theory has evolved into social–cognitive information processing models that explain that what a child observes in any venue has both short-term and long-term influences on the child’s behaviors and cognitions. C. A. Anderson et al.’s (2010) extensive meta-analysis of the effects

L. Rowell Huesmann

2010-01-01

408

MD Anderson study finds lung cancer patients live longer if they use beta-blockers while receiving radiotherapy  

Cancer.gov

Patients with non-small-cell lung cancer survive longer if they are taking beta-blockers while receiving radiotherapy, according to a study of 722 patients published in the cancer journal Annals of Oncology. Researchers at the University of Texas MD Anderson Cancer Center reviewed the progress and outcomes of patients who had received radiotherapy as their main or first line of treatment for cancer.

409

MD Anderson study finds weekly dose reduces a targeted drug's side effects but not its activity against acute lymphocytic leukemia  

Cancer.gov

A potent chemotherapy agent wrapped within a monoclonal antibody selectively destroys the malignant cells responsible for acute lymphocytic leukemia (ALL) in either weekly or monthly dosing, researchers report at the 54th ASH Annual Meeting and Exposition. This "Trojan horse" assault on the cancer cells has significantly increased the response rate among patients with ALL, and now an MD Anderson Cancer Center clinical trial finds that weekly dosing works well and reduces side effects.

410

A detailed pathologic examination of heart tissue from three older patients with Anderson–Fabry disease on enzyme replacement therapy  

Microsoft Academic Search

BackgroundCardiac disease causes considerable morbidity and mortality in men and women with Anderson–Fabry disease (AFD), an X-linked inborn metabolic defect caused by deficiency of the lysosomal enzyme ?-galactosidase A. Treatment with recombinant enzyme preparations aims to attenuate and reverse accumulation of the major enzyme substrate, globotriaosylceramide (Gb3). Pathologic data examining the effect of enzyme replacement therapy (ERT) in vivo are

Mary N. Sheppard; Paul Cane; Richard Florio; Nicholas Kavantzas; Lydia Close; Jaymin Shah; Philip Lee; Perry Elliott

2010-01-01

411

Weak Disorder Localization and Lifshitz Tails  

NASA Astrophysics Data System (ADS)

This paper is devoted to the study of localization of discrete random Schrödinger Hamiltonians in the weak disorder regime. Consider an i.i.d. Anderson model and assume that its left spectral edge is 0. Let ? be the coupling constant measuring the strength of the disorder. For ? small, we prove a Lifshitz tail type estimate and use it to derive localization in a band starting at 0 going up to a distance of the average of the potential. In this energy region, we show that the localization length at energy E is bounded from above by a constant times the square root of the distance between E and the average of the potential. Résumé. Dans cet article, nous étudions la localisation à faible désordre pour des opérateurs de Schrödinger aléatoires discrets. Considérons un modèle d'Anderson i.i.d. dont le bord spectral gauche vaut 0. Soit ? la constante de couplage mesurant le désordre. Pour ? petit, nous démontrons une estimée de type estimée de Lifshitz pour la densité d'états, et nous utilisons cette estimée pour prouver que le spectre de cet opérateur est localisé dans un intervalle allant de l'énergie 0 jusqu'à une distance de l'ordre de de la moyenne du potentiel. Dans cette région d'énergie, la longueur de localisation à une énergie E est majorée par une constante fois la racine de la distance séparant E de la moyenne du potentiel.

Klopp, Frédéric

412

Molecular excitation in sprites  

NASA Astrophysics Data System (ADS)

We have determined the molecular internal energy distribution in the N2 B³IIg state from the fluorescence measured during the observations of sprites during 1995. Spectrally resolved data from two different instruments and three different sprites are compared with theoretical spectra to obtain excited state vibrational distributions. Energy dependent electron excitation cross-sections and laboratory data were used to estimate the energies of electrons producing the red sprite radiance. Implications for chemical production in the mesosphere and critical future measurements are discussed.

Green, B. D.; Fraser, M. E.; Rawlins, W. T.; Jeong, L.; Blumberg, W. A. M.; Mende, S. B.; Swenson, G. R.; Hampton, D. L.; Wescott, E. M.; Sentman, D. D.

413

Enzyme Replacement Therapy in Orphan and Ultra-Orphan Diseases: The Limitations of Standard Economic Metrics as Exemplified by Fabry-Anderson Disease  

Microsoft Academic Search

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

David F. Moore; Markus Ries; Evelyn L. Forget; Raphael Schiffmann

2007-01-01

414

Exact interacting Green's function for the Anderson impurity at high bias voltages  

NASA Astrophysics Data System (ADS)

We describe some exact high-energy properties of a single Anderson impurity connected to two noninteracting leads in a nonequilibrium steady state. In the limit of high bias voltages, and also in the high-temperature limit at thermal equilibrium, the model can be mapped onto an effective non-Hermitian Hamiltonian consisting of two sites, which correspond to the original impurity and its image that is defined in a doubled Hilbert space referred to as Liouville-Fock space. For this, we provide a heuristic derivation using a path-integral representation of the Keldysh contour and the thermal field theory, in which the time evolution along the backward contour is replicated by extra degrees of freedom corresponding to the image. We find that the effective Hamiltonian can also be expressed in terms of charges and currents. From this, it can be deduced that the dynamic susceptibilities for the charges and the current fluctuations become independent of the Coulomb repulsion U in the high bias limit. Furthermore, the equations of motion for the Green's function and two other higher-order correlation functions constitute a closed system. The exact solution obtained from the three coupled equations extends the atomic-limit solution such that the self-energy correctly captures the imaginary part caused by the relaxation processes at high energies. The spectral weights of the upper and lower Hubbard levels depend sensitively on the asymmetry in the tunneling couplings to the left and right leads.

Oguri, Akira; Sakano, Rui

2013-10-01

415

Da Vinci robot assisted Anderson-Hynes dismembered pyeloplasty: technique and 1 year follow-up.  

PubMed

In experienced hands, laparoscopic pyeloplasty is an effective alternative treatment for symptomatic ureteropelvic junction obstruction (UPJO). Although laparoscopic surgery can clearly benefit patients, laparoscopic pyeloplasty using conventional instrumentation is complex. The purpose of this report is to evaluate the feasibility of robot assisted laparoscopic surgery. Eleven pyeloplasties for UPJO were performed via a laparoscopic transperitoneal approach exclusively with the da Vinci Surgical System. The mean procedure time was 197 min (range 110-310 min). All operations were completed laparoscopically with no intraoperative complications and negligible blood loss. All patients recovered rapidly after surgery with excellent functional results at the 1 year follow-up. Our initial experience suggests that robot assisted Anderson-Hynes pyeloplasty is a safe and effective alternative to conventional laparoscopic surgery. In our opinion, robot assisted surgery will allow urologists to perform complex procedures with greater precision, confidence, and better results, as well as enable them to adapt the whole spectrum of laparoscopic procedures to their field. PMID:12942276

Bentas, Wassilios; Wolfram, Marc; Bräutigam, Ronald; Probst, Michael; Beecken, Wolf-Dietrich; Jonas, Dietger; Binder, Jochen

2003-07-09

416

Organic–inorganic hybrids constructed by Anderson-type polyoxoanions and copper coordination complexes  

Microsoft Academic Search

Four organic–inorganic hybrid compounds based on Anderson-type polyoxoanions, namely, {[Cu(2,2?-bpy)(H2O)3]2[Cr(OH)6Mo6O18]}{[Cu(2,2?-bpy)(H2O)Cl][Cu(2,2?-bpy)(H2O)(NO3)][Cr(OH)6Mo6O18]}·18H2O (1), [Cu(2,2?-bpy)(H2O)2Cl]{[Cu(2,2?-bpy)(H2O)2][Cr(OH)6Mo6O18]}·4H2O (2), (H3O){[Cu(2,2?-bpy)(H2O)2]2[Cu(2,2?-bpy)(H2O)]2}[Cr(OH)6Mo6O18]3·36H2O (3), and (H3O){[Cu(2,2?-bpy)(H2O)2]2[Cu(2,2?-bpy)(H2O)]2}[Al(OH)6Mo6O18]3·33H2O (4), were isolated by conventional solution method, and crystal structures have been determined by single-crystal X-ray diffraction. Among them, compound 1 displays a discrete supramolecular structure, compound 2 shows a chainlike structure with chloro-copper complexes as counteranions, and compounds 3 and 4 are

Rui-Ge Cao; Shu-Xia Liu; Ying Liu; Qun Tang; Liang Wang; Lin-Hua Xie; Zhong-Min Su

2009-01-01

417

The Thouless Anderson Palmer equation for an analogue neural network with temporally fluctuating white synaptic noise  

NASA Astrophysics Data System (ADS)

Effects of synaptic noise on the retrieval process of associative memory neural networks are studied from the viewpoint of neurobiological and biophysical understanding of information processing in the brain. We investigate the statistical mechanical properties of stochastic analogue neural networks with temporally fluctuating synaptic noise, which is assumed to be white noise. Such networks, in general, defy the use of the replica method, since they have no energy concept. The self-consistent signal-to-noise analysis (SCSNA), which is an alternative to the replica method for deriving a set of order parameter equations, requires no energy concept and thus becomes available in studying networks without energy functions. Applying the SCSNA to stochastic networks requires the knowledge of the Thouless-Anderson-Palmer (TAP) equation which defines the deterministic networks equivalent to the original stochastic ones. The study of the TAP equation which is of particular interest for the case without energy concept is very less, while it is closely related to the SCSNA in the case with energy concept. This paper aims to derive the TAP equation for networks with synaptic noise together with a set of order parameter equations by a hybrid use of the cavity method and the SCSNA.

Ichiki, Akihisa; Shiino, Masatoshi

2007-08-01

418

Water-quality assessment of the Middle Fork Anderson River watershed, Crawford and Perry Counties, Indiana  

USGS Publications Warehouse

This report, on water quality for streams in Crawford and Perry Counties, Indiana, defines the variation in concentrations of nutrients, inorganic constituents, suspended sediment, bacteria, and phytoplankton in streams, and chlorinated hydrocarbons in bed materials in the Middle Fork Anderson River watershed; identifies areas and sources of water-quality problems; and determines the effects of existing flood-retarding structures on water quality. The data base for this water-quality assessment included five sets of samples collected from September 1975 through July 1976. Temperature, specific conductance, pH, and dissolved-oxygen concentration of water were measured, and stream discharge was estimated at 25 sites. Samples for laboratory analysis were collected at 9 of these sites in September 1975, at 8 of the sites in December 1975, and at 7 of the sites in March, June, and July 1976. Surface-water quality in the watershed is generally good except for problem-causing concentrations of bacteria, dissolved oxygen, and phosphorus at some sites along the main stem during low flow, and manganese at most sites year-round. (Woodard-USGS)

Ayers, M. A.

1978-01-01

419

Quantum-Mechanical Variant of the Thouless-Anderson-Palmer Equation for Error-Correcting Codes  

NASA Astrophysics Data System (ADS)

Statistical mechanics of information has been applied to problems in various research topics of information science and technology [1],[2]. Among those research topics, error-correcting code is one of the most developed subjects. In the research field of error-correcting codes, Nicolas Sourlas showed that the so-called convolutional codes can be constructed by spin glass with infinite range p-body interactions and the decoded message should be corresponded to the ground state of the Hamiltonian [3]. Ruján pointed out that the bit error can be suppressed if one uses finite temperature equilibrium states as the decoding result, instead of the ground state [4], and the so-called Bayes-optimal decoding at some specific condition was proved by Nishimori [5] and Nishimori and Wong [6]. Kabashima and Saad succeeded in constructing more practical codes, namely low-density parity check (LDPC) codes by using the infinite range spin glass model with finite connectivities [7]. They used the so-called TAP (Thouless-Anderson-Palmer) equations to decode the original message for a given parity check.

Inoue, J.; Saika, Y.; Okada, M.

420

Numerical evidence against both mean field and droplet scenarios of the Edwards-Anderson model  

NASA Astrophysics Data System (ADS)

From tempered Monte Carlo simulations, we have obtained accurate probability distributions p(q) of the spin-overlap parameter q for finite Edwards-Anderson (EA) and Sherrington-Kirkpatrick (SK) spin-glass systems at low temperatures. Our results for p(q) follow from averages over 10^5 disordered samples of linear sizes L=4-8 and over 15 ; 000 samples for L=10. In both the SK and EA models, at temperatures as low as 0.2Tsg, where Tsg is the transition temperature, p(q) varies insignificantly with L. This does not fit the trend that the droplet model predicts for large L. We have also calculated correlation functions, F(q1,q2), from which rms deviations, ?p, over different realizations of quenched disorder, as well as thermal fluctuations, w, of q values, follow. Our numerical results for ?p and w scale as ?L and 1/L, respectively, in the SK model. This fits in well with mean field predictions. On the other hand, our data for w and ?p vary little, if at all, for the EA model.

Fernandez, Julio F.; Alonso, Juan J.

2013-03-01

421

Valence Instability and Mass Enhancement in an Extended Periodic Anderson Model  

NASA Astrophysics Data System (ADS)

In CeCu2Si2, CeCu2Ge2 and CeRh1-xIrxIn5, the shape of the superconducting region is asymmetric and the superconducting transtition temperature Tc reaches its maximum far away from the antiferromagnetic quantum critical point. Onishi and Miyake ascribed the asymmetric behavior of Tc to the enhanced valence fluctuations. They introduced the repulsive interaction Ucf between a conduction electron and an f electron, in addition to the Coulomb interaction U between f electrons and studied the periodic Anderson model (PAM) with both U and Ucf (which is the so-called extended PAM). We investigated the valence instability in the extended PAM and two-fold degenerate extended PAM with the dynamical mean field theory. In these models, we found that the valence instability is observed when Ucf is larger than the conduction band width 2W and the f-electron level ?f is deeper than the lower bound of the conduction band, -W. It is also found that the orbital degeneracy suppresses the valence instability. In the parameter region of inducing the valence instability, we investigate the mass enhancement factor Zf-1 which is related to the specific heat.

Sugibayashi, Takashi; Saiga, Yasuhiro; Hirashima, Dai

2008-03-01

422

Validation of the M. D. Anderson Symptom Inventory multiple myeloma module  

PubMed Central

Background The symptom burden associated with multiple myeloma (MM) is often severe. Presently, no instrument comprehensively assesses disease-related and treatment-related symptoms in patients with MM. We sought to validate a module of the M. D. Anderson Symptom Inventory (MDASI) developed specifically for patients with MM (MDASI-MM). Methods The MDASI-MM was developed with clinician input, cognitive debriefing, and literature review, and administered to 132 patients undergoing induction chemotherapy or stem cell transplantation. We demonstrated the MDASI-MM’s reliability (Cronbach ? values); criterion validity (item and subscale correlations between the MDASI-MM and the European Organization for Research and Treatment of Cancer Quality of Life Questionnaire (EORTC QLQ-C30) and the EORTC MM module (QLQ-MY20)), and construct validity (differences between groups by performance status). Ratings from transplant patients were examined to demonstrate the MDASI-MM’s sensitivity in detecting the acute worsening of symptoms post-transplantation. Results The MDASI-MM demonstrated excellent correlations with subscales of the 2 EORTC instruments, strong ability to distinguish clinically different patient groups, high sensitivity in detecting change in patients’ performance status, and high reliability. Cognitive debriefing confirmed that the MDASI-MM encompasses the breadth of symptoms relevant to patients with MM. Conclusion The MDASI-MM is a valid, reliable, comprehensive-yet-concise tool that is recommended as a uniform symptom assessment instrument for patients with MM.

2013-01-01

423

Agalsidase alfa (Replagal™) in the treatment of Anderson-Fabry disease  

PubMed Central

Anderson-Fabry disease (AFD) is an X-linked storage disorder caused by a deficiency of the lysosomal hydrolase a-galactosidase A (AGAL) and the resultant accumulation of its glycosphingolipid substrate (Gb3) in several tissue types. Major morbidity and reduced life expectancy among affected individuals are a consequence of renal, cardiac and cerebrovascular involvement. Symptomatic males and females with AFD have been described, although the onset of clinical manifestations may be delayed and more variable among the latter patient group, partly attributed to lyonization. Agalsidase alfa (Replagal™) is a recombinant formulation of human AGAL which has been demonstrated to modify the course of AFD in treated patients. Factors that may influence clinical outcomes include disease stage at the point of treatment initiation and antibody formation. There is incomplete understanding of AFD pathophysiology. Early diagnosis and timely intervention may be essential. The use of adjunctive therapies, directed at risk reduction (eg, aspirin for stroke prophylaxis), require careful scrutiny, but such agents are likely to be vital components of a comprehensive approach to patient care. Long-term studies may clarify the optimal dose and frequency of enzyme administration. Meanwhile, budding strategies such as chaperone-mediated enzyme enhancement may offer the potential for an alternative or multimodality approach to the management of AFD.

Pastores, Gregory M

2007-01-01

424

Novel edge excitations of two-dimensional electron liquid in a magnetic field  

Microsoft Academic Search

We investiggate the low-energy spectrum of excitations of a compressible electron liquid in a strong magnetic field. These excitations are localized at the periphery of the system. The analysis of a realistic model of a smooth edge yields new branches of acoustic excitation spectrum in addition to the well known edge magnetoplasmon mode. The velocities are found and the observability

I. L. Aleiner; L. I. Glazman

1994-01-01

425

Itinerant versus localized magnetism in CoV1-xMnxSb solutions  

NASA Astrophysics Data System (ADS)

Magnetic properties and resistivity of CoV1-xMnxSb have been investigated. For x<=0.35 Mn states are localized well below EF and polarized. An increase of Mn concentration rises interactions between Mn moments. Resistivity is metallic for low and large Mn contents and semiconducting for x=0.3-0.5, most probably due to Anderson localization effects related to atomic disorder.

Kaczmarska, K.; Pierre, J.; Tobo?a, J.

1999-05-01

426

Disorder in Quantum Vacuum: Casimir-Induced Localization of Matter Waves  

SciTech Connect

Disordered geometrical boundaries such as rough surfaces induce important modifications to the mode spectrum of the electromagnetic quantum vacuum. In analogy to Anderson localization of waves induced by a random potential, here we show that the Casimir-Polder interaction between a cold atomic sample and a rough surface also produces localization phenomena. These effects, that represent a macroscopic manifestation of disorder in quantum vacuum, should be observable with Bose-Einstein condensates expanding in proximity of rough surfaces.

Moreno, G. A. [IFIBA-Departamento de Fisica, FCEyN, UBA, Ciudad Universitaria, 1428 Buenos Aires (Argentina); Theoretical Division, MS B213, Los Alamos National Laboratory, Los Alamos, New Mexico 87545 (United States); Messina, R. [Laboratoire Kastler Brossel, case 74, CNRS, ENS, UPMC, Campus Jussieu, F-75252 Paris Cedex 05 (France); SYRTE--Observatoire de Paris 61, avenue de l'Observatoire, F-75014 Paris (France); Dalvit, D. A. R. [Theoretical Division, MS B213, Los Alamos National Laboratory, Los Alamos, New Mexico 87545 (United States); Lambrecht, A.; Reynaud, S. [Laboratoire Kastler Brossel, case 74, CNRS, ENS, UPMC, Campus Jussieu, F-75252 Paris Cedex 05 (France); Maia Neto, P. A. [Instituto de Fisica, UFRJ, CP 68528, Rio de Janeiro, RJ, 21941-972 (Brazil)

2010-11-19

427

Disordered Electrons in a Strong Magnetic Field: Transfer Matrix Approaches to the Statistics of the Local Density of States  

Microsoft Academic Search

We present two novel approaches to establish the local density of states as an order parameter field for the Anderson transition problem. We first demonstrate for 2D quantum Hall systems the validity of conformal scaling relations which are characteristic of order parameter fields. Second we show the equivalence between the critical statistics of eigenvectors of the Hamiltonian and of the

Axel Dohmen; Peter Freche; Martin Janssen

1996-01-01

428

Soliton excitation in superlattice.  

National Technical Information Service (NTIS)

Excitation of soliton in superlattice has been investigated theoretically. It is noted that the soliton velocity u and the length L depend on the amplitude E(sub 0) and that an increase in the amplitude causes soliton width L to approach zero and the velo...

S. Y. Mensah F. K. A. Allotey N. G. Mensah A. K. Twum

1995-01-01

429

On Planetary Evolution and the Evolution of Planetary Science During the Career of Don Anderson  

NASA Astrophysics Data System (ADS)

The planets of our solar system have long been viewed by Don Anderson as laboratories for testing general aspects of planetary evolution and as points of comparison to the Earth. I was fortunate to have been a student 39 years ago in a course at Caltech that Don taught with Bob Kovach on the interiors of the Earth and the planets. At that time, Mariner 4 had not yet flown by Mars, the lunar Ranger program was still in progress, and it was permissible to entertain the hypothesis that all of the terrestrial planets were identical in bulk composition. In the last four decades spacecraft have visited every planet from Mercury to Neptune; samples from the Moon, Mars, asteroids, and comets reside in our laboratories; and more than 100 planets have been discovered orbiting other stars. More importantly, traditionally distinct fields have merged to the point where planetary scientists must be conversant with the findings and modes of thinking from astronomy and biology as well as the geosciences. A few examples illustrate this confluence. Theoretical models for the structure of the atmospheres of gas-giant planets led to the first astronomical detection of an extrasolar planetary atmosphere for the transiting planet HD209458b. Although the atmospheric models were based on those for solar-system gas giants, the 3.5-day orbital period means that this planet is 100 times closer to its star than Jupiter is to the Sun, its effective temperature is 1100 K, and the detected signature of the planetary atmosphere was absorption by neutral sodium. Sodium in Mercury's exosphere, detected astronomically from Earth, figures into the question of how the terrestrial planets came to have distinct bulk compositions. Hypotheses to account for Mercury's high uncompressed density, and by inference its high ratio of metal to silicate, range from chemical gradients in the early solar nebula to preferential removal of silicates from a differentiated protoplanet by nebular heating or giant impact disruption, processes that would have affected the final composition of the other inner planets to lesser degrees. These hypotheses will be distinguishable by future remote sensing measurements from a spacecraft in Mercury orbit, but all lead to the prediction that volatile species such as sodium should be deficient in Mercury's silicate fraction. The most recent models for Mercury's exosphere are consistent with the idea that the required fresh supply of sodium from Mercury's surface is no greater than that predicted for meteorite infall. One of the leading questions driving the current exploration of Mars is whether the surface or subsurface was ever conducive to the origin and evolution of life. Sites of hydrothermal circulation within the crust may have provided the necessary energy and chemical building blocks. Remote sensing of candidate hydrothermal minerals at the Martian surface is the leading technique being used to seek such sites, but paleomagnetism may offer another route. Several hypotheses link hydrothermal activity to either the formation of magnetic carriers during the lifetime of the Martian dynamo or the alteration of such carriers after the dynamo ceased, leading to the possibility that high-resolution mapping of crustal magnetism may provide a prospecting tool for promising Martian biological habitats. As Don Anderson showed us by example throughout his career, students of the Earth need not confine their attention to a single planet or even a single planetary system. The lessons from diverse fields that planetary scientists must master to stay current will keep all of us --- like Don --- young and curious.

Solomon, S. C.

2003-12-01

430

The pioneer woman's view of migraine: Elizabeth Garrett Anderson's thesis "Sur la migraine".  

PubMed

This is a presentation of a doctoral thesis of 1870. The author was English but the thesis and the examinations were in French. Elizabeth Garrett Anderson, usually referred to as E.G.A., was the first woman in Britain to obtain the title of M.D., but not the first in Europe. Nadeshda Prokofevna Suslova, a Russian, received her M.D. in 1867 in Zurich, the most liberal university at that time, soon to be flooded by female students from Russia. E.G.A. had been applying to the few possible European universities but she settled for Paris after the Empress Eugenie had decided that she should be accepted there. This meant that she could succeed without having to be a Paris resident, just by writing a thesis and passing a series of examinations presided over by Paul Broca. This was important as she was already conducting private and dispensary practice, and could not find a locum (she insisted on a woman). E.G.A. had suffered many setbacks, for being a woman, as such being unacceptable in dissection rooms and operating theatres, and generally in a professional career where women were unheard of. She was finally permitted to receive her medical diploma from the Worshipful Society of Apothecaries of London. She wrote about her thesis: "I have chosen Headache as its subject. I had to find a subject which could be well studied without post-mortem observations, of which I can have but very few in either private or dispensary practice; and I wished also to take a large subject, one that demanded some insight into the harmony that exists between the main physiological functions." Marcia Wilkinson (M.W.), who worked in the Elizabeth Garrett Anderson Hospital in London for 35 years, heard there of E.G.A.'s thesis on migraine and sent for it from Paris. In 1966 she translated it into English from the original French, being interested both in the subject and in the person of this resolute and lucid woman. When H. Isler found the French thesis in the British Library he intended to translate it but, after discussion, we decided on a joint effort (95% of the translation is by M.W.; very few details were changed, and some footnotes added for better understanding). We think that E.G.A.'s text is a classic, showing profound understanding, sound practical advice, and also, in its theoretical part, the limits of neurophysiological knowledge in Paris when Brown-Sequard was "charge des cours" there. We may add that in her various examinations she had to answer questions, in French, on the use of footprints by the police, the general nature of fishes, toxic fishes, electric fishes, cod liver oil, and the secretion of tears. She earned much applause from the public, which consisted of male French students, and the overt appreciation of Paul Broca, head examiner, and Dr Wurtz, the Dean of the Faculte de Médecine. The impact of her thesis in the 19th century was modest. It appears to be rather marginal in the German literature of the early 20th century, but it has imprinted the management of migraine at the City of London Migraine Clinic in the last thirty years. The importance of nutrition, regular meals, regular habits, the need to supplement analgesics with antiemetics, and the treatment of the attack with rest, and great quantities of hot tea, were certainly related to E.G.A.'s doctrine. The internationally prevailing recommendation to give antiemetics, and then only analgesics, as well as the combination of both in one tablet, may thus be traced back to E.G.A. via the teachings of M.W. and Nat Blau. PMID:10099853

Wilkinson, M; Isler, H

1999-01-01

431

Organic-inorganic hybrids constructed by Anderson-type polyoxoanions and copper coordination complexes  

SciTech Connect

Four organic-inorganic hybrid compounds based on Anderson-type polyoxoanions, namely, {l_brace}[Cu(2,2'-bpy)(H{sub 2}O){sub 3}]{sub 2}[Cr(OH){sub 6}Mo{sub 6}O{sub 18}]{r_brace}{l_brace}[Cu(2,2'-bpy)(H{sub 2}O)Cl][Cu(2,2'-bpy) (H{sub 2}O)(NO{sub 3})][Cr(OH){sub 6}Mo{sub 6}O{sub 18}]{r_brace}.18H{sub 2}O (1), [Cu(2,2'-bpy)(H{sub 2}O){sub 2}Cl]{l_brace}[Cu(2,2'-bpy)(H{sub 2}O){sub 2}][Cr(OH){sub 6}Mo{sub 6}O{sub 18}]{r_brace}.4H{sub 2}O (2), (H{sub 3}O){l_brace}[Cu(2,2'-bpy)(H{sub 2}O){sub 2}]{sub 2}[Cu(2,2'-bpy)(H{sub 2}O)]{sub 2}{r_brace}[Cr(OH){sub 6}Mo{sub 6}O{sub 18}]{sub 3}.36H{sub 2}O (3), and (H{sub 3}O){l_brace}[Cu(2,2'-bpy)(H{sub 2}O){sub 2}]{sub 2}[Cu(2,2'-bpy)(H{sub 2}O)]{sub 2}{r_brace}[Al(OH){sub 6}Mo{sub 6}O{sub 18}]{sub 3}.33H{sub 2}O (4), were isolated by conventional solution method, and crystal structures have been determined by single-crystal X-ray diffraction. Among them, compound 1 displays a discrete supramolecular structure, compound 2 shows a chainlike structure with chloro-copper complexes as counteranions, and compounds 3 and 4 are isomorphic and exhibit unique 3D open frameworks with lattice water molecules residing in the channels. The compounds 3 and 4 represent the first example of 3D organic-inorganic hybrid compounds in the TMs/2,2'-bpy/POMs system. Investigation of the reaction conditions reveals that the geometry and size of the anions together with its coordinating abilities to the metal centers have a decisive influence on both the composition and the dimensionality of the final compounds. - Graphical Abstract: Four organic-inorganic hybrids based on Anderson-type polyoxoanions have been synthesized. Compound 1 displays a discrete structure, 2 shows a chainlike structure, 3 and 4 are isomorphic and exhibit unique 3D open frameworks with lattice waters residing in the channels. The different structures suggest that the overall structures of the compounds are influenced by the nature of the acidic anions.

Cao Ruige [Key Laboratory of Polyoxometalates Science of the Ministry of Education, College of Chemistry, Northeast Normal University, Changchun City, JiLin 130024 (China); Liu Shuxia [Key Laboratory of Polyoxometalates Science of the Ministry of Education, College of Chemistry, Northeast Normal University, Changchun City, JiLin 130024 (China)], E-mail: liusx@nenu.edu.cn; Liu Ying; Tang Qun; Wang Liang; Xie Linhua; Su Zhongmin [Key Laboratory of Polyoxometalates Science of the Ministry of Education, College of Chemistry, Northeast Normal University, Changchun City, JiLin 130024 (China)

2009-01-15

432

Organic-inorganic hybrids constructed by Anderson-type polyoxoanions and copper coordination complexes  

NASA Astrophysics Data System (ADS)

Four organic-inorganic hybrid compounds based on Anderson-type polyoxoanions, namely, {[Cu(2,2?-bpy)(H2O)3]2[Cr(OH)6Mo6O18]}{[Cu(2,2?-bpy)(H2O)Cl][Cu(2,2?-bpy)(H2O)(NO3)][Cr(OH)6Mo6O18]}·18H2O (1), [Cu(2,2?-bpy)(H2O)2Cl]{[Cu(2,2?-bpy)(H2O)2][Cr(OH)6Mo6O18]}·4H2O (2), (H3O){[Cu(2,2?-bpy)(H2O)2]2[Cu(2,2?-bpy)(H2O)]2}[Cr(OH)6Mo6O18]3·36H2O (3), and (H3O){[Cu(2,2?-bpy)(H2O)2]2[Cu(2,2?-bpy)(H2O)]2}[Al(OH)6Mo6O18]3·33H2O (4), were isolated by conventional solution method, and crystal structures have been determined by single-crystal X-ray diffraction. Among them, compound 1 displays a discrete supramolecular structure, compound 2 shows a chainlike structure with chloro-copper complexes as counteranions, and compounds 3 and 4 are isomorphic and exhibit unique 3D open frameworks with lattice water molecules residing in the channels. The compounds 3 and 4 represent the first example of 3D organic-inorganic hybrid compounds in the TMs/2,2?-bpy/POMs system. Investigation of the reaction conditions reveals that the geometry and size of the anions together with its coordinating abilities to the metal centers have a decisive influence on both the composition and the dimensionality of the final compounds.

Cao, Rui-Ge; Liu, Shu-Xia; Liu, Ying; Tang, Qun; Wang, Liang; Xie, Lin-Hua; Su, Zhong-Min

2009-01-01

433

Adult ependymal tumors: prognosis and the M. D. Anderson Cancer Center experience  

PubMed Central

Ependymomas in adults are rare and often misdiagnosed. This study reports on a series of adult patients with confirmed ependymoma treated at The University of Texas M. D. Anderson Cancer Center (MDACC). Patients aged >17 and with ependymoma were identified, and clinical data were collected by retrospective chart review. Descriptive statistics were used to describe the clinical data, Kaplan–Meier methods were used to generate survival curves, and Cox proportional hazards models were used to evaluate the association of clinical characteristics with survival. This series included 123 adult patients [51% male; median age 39 years (18–72)]. Forty had tumors in the brain, 80 in the spine, and 3 had both. The majority were Grade I/II lesions (108) vs Grade III (anaplastic; 15). Eighteen patients had tumors that were reclassified as ependymal tumors at MDACC. The most common presenting symptom was pain, with an average of 4 symptoms reported prior to diagnosis. Sixty-three percent of patients had a gross total resection, and 49% received radiation therapy. Average follow-up was 5.5 years, and 13% had died. Median time to recurrence was 21 months (Grade II) brain and 18 months (Grade III). Worse outcome measured by overall and progression-free survival were associated with brain location (P = .01, P = .04) and tumor anaplasia (P = .0025, P = .001). An MIB-1 > 10 was associated with worse outcome (P = .03). Tumor grade and brain location are associated with a worse prognosis. Reclassification of ependymoma by neuropathologists is common. Results of this study have lead to a multicenter study to further define important diagnostic and prognostic variables for adults with ependymoma.

Armstrong, Terri S.; Vera-Bolanos, Elizabeth; Bekele, B. Nebiyou; Aldape, Kenneth; Gilbert, Mark R.

2010-01-01

434

The University of Texas M.D. Anderson Cancer Center Proton Therapy Facility  

NASA Astrophysics Data System (ADS)

The University of Texas M.D. Anderson Cancer Center (MDACC), in partnership with Sanders Morris Harris Inc., a Texas-based investment banking firm, and The Styles Company, a developer and manager of hospitals and healthcare facilities, is building a proton therapy facility near the MDACC main complex at the Texas Medical Center in Houston, Texas USA. The MDACC Proton Therapy Center will be a freestanding, investor-owned radiation oncology center offering state-of-the-art proton beam therapy. The facility will have four treatment rooms: three rooms will have rotating, isocentric gantries and the fourth treatment room will have capabilities for both large and small field (e.g. ocular melanoma) treatments using horizontal beam lines. There will be an additional horizontal beam room dedicated to physics research and development, radiation biology research, and outside users who wish to conduct experiments using proton beams. The first two gantries will each be initially equipped with a passive scattering nozzle while the third gantry will have a magnetically swept pencil beam scanning nozzle. The latter will include enhancements to the treatment control system that will allow for the delivery of proton intensity modulation treatments. The proton accelerator will be a 250 MeV zero-gradient synchrotron with a slow extraction system. The facility is expected to open for patient treatments in the autumn of 2005. It is anticipated that 675 patients will be treated during the first full year of operation, while full capacity, reached in the fifth year of operation, will be approximately 3,400 patients per year. Treatments will be given up to 2-shifts per day and 6 days per week.

Smith, Alfred; Newhauser, Wayne; Latinkic, Mitchell; Hay, Amy; McMaken, Bruce; Styles, John; Cox, James

2003-08-01

435

Cushing's syndrome secondary to ectopic ACTH secretion: The University of Texas MD Anderson Cancer Center Experience  

PubMed Central

Background Cushing's syndrome (CS) secondary to ectopic ACTH secretion (EAS) has been described in association with a variety of tumors. The current experience with this syndrome is based on a few case series and individual case reports. Limited data are available about the tumors associated with CS-EAS in cancer center setting. This report describes CS-EAS at MD Anderson Cancer Center to further enhance our understanding and management of this syndrome. Methods This is a retrospective review for 43 patients with CS-EAS who were diagnosed between 1979 and 2009 at our institution. Results Different neuroendocrine tumors were associated with CS-EAS. Twenty one patients (48.9%) had tumors located in the chest cavity with bronchial carcinoid and small cell lung cancer representing the two most common causes. The ACTH source remained occult in 4 patients (9.3 %) despite extensive work-up. Clinical presentation was variable and the classical features of CS were not evident in some patients. Death occurred in 27 patients (62.8%) and the median overall survival was 32.2 months. Major morbidities included new onset or worsening hyperglycemia (77%), symptomatic venous thromboembolism (14%) and infections (23%). Conclusions In CS-EAS cases seen at a comprehensive cancer center, tumors originating in the chest cavity were the leading tumors associated with this syndrome. We suspect that CS-EAS is underreported because of the atypical presentation in some cases. Thus, we suggest careful evaluation of patients with neuroendocrine tumors to avoid missing co-existing CS-EAS.

Ejaz, Shamim; Vassilopoulou-Sellin, Rena; Busaidy, Naifa L.; Hu, Mimi I.; Waguespack, Steven G.; Jimenez, Camilo; Ying, Anita K.; Cabanillas, Maria; Abbara, Maher; Habra, Mouhammed Amir

2011-01-01

436

Chronic renal failure, dialysis, and renal transplantation in Anderson-Fabry disease.  

PubMed

Anderson-Fabry disease (AFd) is a rare, inherited, x-linked disease characterized by the deficiency of the lysosomal enzymatic alpha-galactosidase A activity (alpha-Gal-A). The enzyme defect leads to progressive accumulation of glycosphingolipids (GL) in all kinds of cells, tissues, organs, and body fluids. The clinical manifestations are very protean, the residual activity of alpha-Gal-A and/or different gene mutations might explain different phenotypes, but as yet these concepts have not been proven. Usually, patients with AFd show 3 clinical phases, more evident in men than in heterozygous women. The first phase (childhood and adolescence) is characterized by myalgia, arthralgia, acroparesthesia, fever, cutaneous angiokeratomas, and corneal opacities. The second phase is characterized mainly by renal involvement. In the third phase, severe renal impairment and involvement of cerebrovascular and cardiovascular systems are present. The progression to end-stage renal disease (ESRD) is common in hemizygous males (3rd-5th decade of life); usually, death occurs because of cerebral and/or cardiovascular complications in patients undergoing chronic dialysis therapies. The survival of patients with AFd in dialysis is better than in diabetic patients, but it clearly is decreased compared with uremic patients with other nephropathies, despite a lower mean age of uremia (50 versus 60 y). The outcome of kidney transplantation is similar to that found in other patients with ESRD, despite controversial issues published in the past. The use of a kidney donor with normal alpha-Gal-A activity in the control of the metabolic systemic disease is unproven. The recurrence of GL deposits in the kidney graft has been documented rarely. The definitive treatment for AFd is enzyme replacement therapy with purified alpha-Gal-A produced by a genetically engineered human cell line or Chinese hamster oocytes: relatively short-term studies have shown a significant treatment effect on clinical outcome measures. PMID:15490423

Sessa, Adalberto; Meroni, Mietta; Battini, Graziana; Righetti, Marco; Mignani, Renzo

2004-09-01

437

NRG study of a generalized Anderson impurity model with non Fermi liquid fixed point.  

NASA Astrophysics Data System (ADS)

We study with the Wilson numerical renormalization group method the phase diagram of a twofold orbitally degenerate doubly occupied Anderson impurity model. Strikingly, the model presents a non-trivial fixed point, similar to that of the two-impurity Kondo problem, which separates a Kondo-screened regime from a Kondo-unscreened one. This novel fixed point is even more robust than that, since it can only be destabilized by orbital or gauge symmetry breaking. We calculate the impurity spectral function (DOS) which shows quite an interesting behavior across the fixed point. In the Kondo screened regime and close to the fixed point the DOS displays, riding on top of a broader peak, a very narrow resonance at the Fermi level. The resonance shrinks upon approaching the fixed point, and finally disappears at the fixed point. Beyond that, in the Kondo-unscreened regime, the narrow resonance is now replaced by a narrow pseudogap gradually opening up. The doubly occupied model has electron-hole symmetry; however the novel fixed point exists even without that symmetry. In general the DOS pseudogap in the Kondo-unscreened regime gets partly filled in, but will still pin the chemical potential. While this impurity model is interesting per se, we are pursuing its use as a tool to understand, via Dynamical Mean Field Theory, the behavior of a strongly correlated lattice model close to the Mott transition. We argue that this lattice model should encounter the non-trivial fixed point just before the Mott transition and react to its instability by spontaneous generation of a superconducting order parameter.

de Leo, Lorenzo; Fabrizio, Michele

2004-03-01

438

Anderson-Stuart Model to Analyze DC Conductivity of Fluormica Glassceramics  

NASA Astrophysics Data System (ADS)

The Glassceramics (GC) are essentially polycrystalline solids in the matrix of residual glass phase. They are interesting in view of the scientific and technological importance. The fluormica glass system (K2O MgO Al2O3 MgF2 B2O3 SiO2) was prepared for a specific composition by melt quench technique, and the fluormica GC phase was obtained by giving heat treatment at 1123 K to the glass sample [1]. The transition from glass to GC was confirmed using XRD. The fluormica are structural analogues of natural mica. Here the K+ ions are weakly cross-bonded in tetrahedral sheet. Fluormica exhibits an unusual combination of properties like machinability, resistance to withstand high temperatures, high dielectric constant with low loss, and high DC resistivity [2]. We have measured the DC conductivity (s) as a function of temperature (T) using the two-probe method. These measurements have been analyzed using the Anderson-Stuart (AS) model [3]. The Arrhenius plots of s vs T exhibit two linear regions, and the activation energy of the GC is found to be larger than that of glass [1]. The physical parameters selected to fit s vs T using the AS model which describes fairly well the ionic conduction in the fluormica glass system, are found to be reasonable. However, it appeared that a distribution of activation energies instead of single activation energy is necessary, to explain the experimental data. Dr Mahntappa S Jogad would like to acknowledge the American Physical Society’s Kilambi Ramavataram Committee and the Fulbright Foreign Scholarship Board, for a visiting fellowship. References: 1. M S Jogad, B S Krishnamurthy and V Saraswati, Asian Journal of Physics, 6, Nos, 142, 158 (1997) 2. Mahantappa S Jogad, B S Krishnamurthy and V Saraswati, J Non Crystalline Solids (Communicated). 3. M. D. Ingram, Phys. Chem. Glasses, 28, 215 (1987).

Jogad, Mahantappa S.; Krishnamurthy, B. S.; Saraswati, V.

2001-03-01

439

DFT treatment of transport through Anderson junction: exact results and approximations  

NASA Astrophysics Data System (ADS)

Since the pioneering break-junction experiments of Reed and Tour measuring the conductance of dithiolated benzene between gold leads, many researchers in physics and chemistry have been calculating conductance for such systems using density functional theory (DFT). Off resonance, the predicted current is often 10-100 times larger than that measured. This error is often ascribed to the application of ground-state DFT to a non-equilibrium problem. I will argue that, in fact, this is largely due to errors in the density functional approximations in popular use, rather than necessarily errors in the methodology. A stark illustration of this principle is the ability of DFT to reproduce the exact transmission through an Anderson junction at zero-temperature and weak bias, including the Kondo plateau, but only if the exact ground-state density functional is used. In fact, this case can be used to reverse-engineer the exact functional for this problem. Popular approximations can also be tested, including both smooth and discontinuous functionals of the density, as well as symmetry-broken approaches. [4pt] [1] Kondo effect given exactly by density functional theory, J. P. Bergfield, Z. Liu, K. Burke, and C. A. Stafford, arXiv:1106.3104; [0pt] [2] Broadening of the Derivative Discontinuity in Density Functional Theory, F. Evers, and P. Schmitteckert, arXiv:1106.3658; [0pt] [3] DFT-based transport calculations, Friedel's sum rule and the Kondo effect, P. Tr"oster, P. Schmitteckert, and F. Evers, arXiv:1106.3669; [0pt] [4] Towards a description of the Kondo effect using time-dependent density functional theory, G. Stefanucci, and S. Kurth, arXiv:1106.3728.

Burke, Kieron

2012-02-01

440

Branched relaxation of electronic excitations in rare-gas crystals with traps of different types  

Microsoft Academic Search

Luminescence excitation spectra are used as a probe of competition between exciton traps of two types: exciton localization centres and centres of exciton trapping followed by transforming to another electronic state. A strong competition between localization and transforming centres takes place only under excitation above the dielectric gap Eg (with energy E > Eg ). For E < Eg the

A. N. Ogurtsov; A. M. Ratner; E. V. Savchenko; V. Kisand; S. Vielhauer

2000-01-01

441

Magnetostrictive resonance excitation  

DOEpatents

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.

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

1992-01-01

442

[Laufberger's excitation theory].  

PubMed

The author gives an account of V. Laufberger's Excitation theory at the occasion of the 100th anniversary of his birthday. This work was published as a monograph in 1947 and contains many data which foresee the further development of neuro-sciences and other scientific disciplines. From a certain aspect it is more cybernetic than Wiener's "Cybernetics" published one year later. It applies in a genial way the principle of logical elements made up of binary functional elements, backfeeds, parallel organization of neuron networks, and memories based on so-called spinning excitations. It is the first modern model of cerebral activity. It combines within one system the neuron and psychic level of organization of the brain. PMID:2224962

Radil, T

1990-08-24

443

Trapped and excited  

SciTech Connect

The trapped w modes of stars with a first order phase transition (a density discontinuity) are computed and the excitation of some of the modes of these stars by a perturbing shell is investigated. Attention is restricted to odd parity (''axial'') w modes. With R the radius of the star, M its mass, R{sub i} the radius of the inner core and M{sub I} the mass of such core, it is shown that stars with R/M{ge}5 can have several trapped w modes, as long as R{sub i}/M{sub i}{lt}2.6. Excitation of the least damped w mode is confirmed for a few models. All of these stars can only exist, however, for values of the ratio between the densities of the two phases, greater than {approximately}46. We also show that stars with a phase transition and a given value of R/M can have far more trapped modes than a homogeneous single density star with the same value of R/M, provided both R/M and R{sub i}/M{sub i} are smaller than 3. If the phase transition is very fast, most of the stars with trapped modes are unstable to radial oscillations. We compute the time of instability, and find it to be comparable to the damping of the w mode excited in most cases where w-mode excitation is likely. If on the other hand the phase transition is slow, all the stars are stable to radial oscillations.

Andrade, Zeferino

2001-06-15

444

Excitable scale free networks  

NASA Astrophysics Data System (ADS)

When a simple excitable system is continuously stimulated by a Poissonian external source, the response function (mean activity versus stimulus rate) generally shows a linear saturating shape. This is experimentally verified in some classes of sensory neurons, which accordingly present a small dynamic range (defined as the interval of stimulus intensity which can be appropriately coded by the mean activity of the excitable element), usually about one or two decades only. The brain, on the other hand, can handle a significantly broader range of stimulus intensity, and a collective phenomenon involving the interaction among excitable neurons has been suggested to account for the enhancement of the dynamic range. Since the role of the pattern of such interactions is still unclear, here we investigate the performance of a scale-free (SF) network topology in this dynamic range problem. Specifically, we study the transfer function of disordered SF networks of excitable Greenberg-Hastings cellular automata. We observe that the dynamic range is maximum when the coupling among the elements is critical, corroborating a general reasoning recently proposed. Although the maximum dynamic range yielded by general SF networks is slightly worse than that of random networks, for special SF networks which lack loops the enhancement of the dynamic range can be dramatic, reaching nearly five decades. In order to understand the role of loops on the transfer function we propose a simple model in which the density of loops in the network can be gradually increased, and show that this is accompanied by a gradual decrease of dynamic range.

Copelli, M.; Campos, P. R. A.

2007-04-01

445

Fragment-based configuration interaction wave function to calculate environmental effect on excited states in proteins and solutions  

NASA Astrophysics Data System (ADS)

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.

Hasegawa, Jun-ya

2013-05-01

446

Harmonically excited orbital variations  

SciTech Connect

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.

Morgan, T.

1985-08-06

447

Ultrafast excited state dynamics of tris-  

NASA Astrophysics Data System (ADS)

Time resolved anisotropy measurements and time dependent transient absorption measurements are used to study the evolution of the photoexcited Franck-Condon state to the formation of the long-lived triplet metal-to-ligand charge-transfer (3MLCT) state in tris- (2,2'-bipyridine) ruthenium(II). [Ru(bpy)3]2+ represents a large class of inorganic compounds with interesting and potentially applicable photophysical properties. These compounds have generated much interest in the inorganic chemistry community because their photophysical properties are easily manipulated by synthetic chemistry methods. However, little remains known about the processes which govern the evolution from initial photoexcitation to the formation of the long-lived excited state. Metal to ligand charge transfer, when used to describe inorganic compounds, is a description of how the compound reacts to the absorption of light. Typically, these inorganic compounds are made of a transition metal with organic ligands, consisting of carbon, nitrogen and oxygen, coordinated in a highly symmetrical manner to the metal center. The highest occupied molecular orbitals (HOMO) in these compounds are isoenergetic with the frontier atomic orbitals of the metal and are localized to the metal center. The lowest unoccupied molecular orbitals (LUMO) are isoenergetic with the coordinating ligand orbitals and are localized to the ligands. Upon absorption of light in which an electron is promoted from the HOMO to the LUMO, the electron is excited from the metal to the ligands. Time dependent transie