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1

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

2

Anderson localization in nonlocal nonlinear media.  

PubMed

We theoretically and numerically investigate the effect of focusing and defocusing nonlinearities on Anderson localization in highly nonlocal media. A perturbative approach is developed to solve the nonlocal nonlinear Schrödinger equation in the presence of a random potential, showing that nonlocality stabilizes Anderson states. PMID:22297343

Folli, Viola; Conti, Claudio

2012-02-01

3

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

4

Bistability of anderson localized States in nonlinear random media.  

PubMed

We study wave transmission through one-dimensional random nonlinear structures and predict a novel effect resulting from an interplay of nonlinearity and disorder. We reveal that, while weak nonlinearity does not change the typical exponentially small transmission in the regime of the Anderson localization, it affects dramatically the disorder-induced localized states excited inside the medium leading to bistable and nonreciprocal resonant transmission. Our numerical modeling shows an excellent agreement with theoretical predictions based on the concept of a high-Q resonator associated with each localized state. This offers a new way for all-optical light control employing statistically homogeneous random media without regular cavities. PMID:20366536

Shadrivov, Ilya V; Bliokh, Konstantin Y; Bliokh, Yuri P; Freilikher, Valentin; Kivshar, Yuri S

2010-03-26

5

Electronic control of optical Anderson localization modes.  

PubMed

Anderson localization of light has been demonstrated in a few different dielectric materials and lithographically fabricated structures. However, such localization is difficult to control, and requires strong magnetic fields or nonlinear optical effects, and electronic control has not been demonstrated. Here, we show control of optical Anderson localization using charge carriers injected into more than 100 submicrometre-scale p-n diodes. The diodes are embedded into the cross-section of the optical waveguide and are fabricated with a technology compatible with the current electronics industry. Large variations in the output signal, exceeding a factor of 100, were measured with 1 V and a control current of 1 mA. The transverse footprint of our device is only 0.125 µm(2), about five orders of magnitude smaller than optical two-dimensional lattices. Whereas all-electronic localization has a narrow usable bandwidth, electronically controlled optical localization can access more than a gigahertz of bandwidth and creates new possibilities for controlling localization at radiofrequencies, which can benefit applications such as random lasers, optical limiters, imagers, quantum optics and measurement devices. PMID:24681777

Mookherjea, Shayan; Ong, Jun Rong; Luo, Xianshu; Guo-Qiang, Lo

2014-05-01

6

Dynamical Localization for Unitary Anderson Models  

NASA Astrophysics Data System (ADS)

This paper establishes dynamical localization properties of certain families of unitary random operators on the d-dimensional lattice in various regimes. These operators are generalizations of one-dimensional physical models of quantum transport and draw their name from the analogy with the discrete Anderson model of solid state physics. They consist in a product of a deterministic unitary operator and a random unitary operator. The deterministic operator has a band structure, is absolutely continuous and plays the role of the discrete Laplacian. The random operator is diagonal with elements given by i.i.d. random phases distributed according to some absolutely continuous measure and plays the role of the random potential. In dimension one, these operators belong to the family of CMV-matrices in the theory of orthogonal polynomials on the unit circle. We implement the method of Aizenman-Molchanov to prove exponential decay of the fractional moments of the Green function for the unitary Anderson model in the following three regimes: In any dimension, throughout the spectrum at large disorder and near the band edges at arbitrary disorder and, in dimension one, throughout the spectrum at arbitrary disorder. We also prove that exponential decay of fractional moments of the Green function implies dynamical localization, which in turn implies spectral localization. These results complete the analogy with the self-adjoint case where dynamical localization is known to be true in the same three regimes.

Hamza, Eman; Joye, Alain; Stolz, Günter

2009-11-01

7

Universalities: From Anderson Localization To Quantum Chaos  

Microsoft Academic Search

Contents1. Introduction 51.1. Impurity States 61.2. Impurity Bands 81.3. Anderson Model 92. Quantum Interference Effects in Disordered Conductors 112.1. Waves in Random Media 122.2. Aharonov-Bohm Oscillations 132.2.1. hc=e 132.2.2. hc=2e 152.3. Variations in Random Potential 162.4. Diffusion 172.5. Thouless Approach 193. Scaling Theory of Localization 204. Perturbation Theory of Disordered Metals 224.1. Green Functions 224.2. Random Potential 234.3. Diagrammatics 244.4....

Boris L. Altshuler; B. D. Simons

1985-01-01

8

Random nanolasing in the Anderson localized regime  

NASA Astrophysics Data System (ADS)

The development of nanoscale optical devices for classical and quantum photonics is affected by unavoidable fabrication imperfections that often impose performance limitations. However, disorder may also enable new functionalities, for example in random lasers, where lasing relies on random multiple scattering. The applicability of random lasers has been limited due to multidirectional emission, lack of tunability, and strong mode competition with chaotic fluctuations due to a weak mode confinement. The regime of Anderson localization of light has been proposed for obtaining stable multimode random lasing, and initial work concerned macroscopic one-dimensional layered media. Here, we demonstrate on-chip random nanolasers where the cavity feedback is provided by the intrinsic disorder. The strong confinement achieved by Anderson localization reduces the spatial overlap between lasing modes, thus preventing mode competition and improving stability. This enables highly efficient, stable and broadband wavelength-controlled lasers with very small mode volumes. Furthermore, the complex interplay between gain, dispersion-controlled slow light, and disorder is demonstrated experimentally for a non-conservative random medium. The statistical analysis shows a way towards optimizing random-lasing performance by reducing the localization length, a universal parameter.

Liu, J.; Garcia, P. D.; Ek, S.; Gregersen, N.; Suhr, T.; Schubert, M.; Mørk, J.; Stobbe, S.; Lodahl, P.

2014-04-01

9

Kolmogorov turbulence, Anderson localization and KAM integrability  

NASA Astrophysics Data System (ADS)

The conditions for emergence of Kolmogorov turbulence, and related weak wave turbulence, in finite size systems are analyzed by analytical methods and numerical simulations of simple models. The analogy between Kolmogorov energy flow from large to small spacial scales and conductivity in disordered solid state systems is proposed. It is argued that the Anderson localization can stop such an energy flow. The effects of nonlinear wave interactions on such a localization are analyzed. The results obtained for finite size system models show the existence of an effective chaos border between the Kolmogorov-Arnold-Moser (KAM) integrability at weak nonlinearity, when energy does not flow to small scales, and developed chaos regime emerging above this border with the Kolmogorov turbulent energy flow from large to small scales.

Shepelyansky, D. L.

2012-06-01

10

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

11

Anderson localization and colocalization of spatially entangled photons  

NASA Astrophysics Data System (ADS)

We explore the propagation of light in a two-photon state in disordered optical systems that induce Anderson localization. We show that entangled-photon pairs demonstrate a surprising behavior that we call Anderson colocalization: While neither photon exhibits Anderson localization, the spatial correlations of the pair remain intact. Furthermore, we show that entangled-photon pairs colocalize faster than classical light localizes in the same system. We also explore the propagation of anticorrelated and partially entangled photon pairs in such systems. The results are developed using a linear systems theory that extends the scope of quantum imaging to incorporate disordered systems.

Abouraddy, Ayman F.; Di Giuseppe, Giovanni; Christodoulides, Demetrios N.; Saleh, Bahaa E. A.

2012-10-01

12

Observing transverse Anderson localization in random air line based fiber  

NASA Astrophysics Data System (ADS)

The concept of Anderson localization has been applied to electromagnetic waves for decades and strong photon localization effect has been observed in many two-dimensional systems including optical lattice and optical fibers. Among different types of optical fibers, both fibers with and without air hole were investigated. Air hole based fiber has significant higher refractive index contrast than other fibers which allow much lower filling fraction in order to observe Anderson localization. In a previous research, Anderson localization was observed near the fiber edge with an air fillfraction of 5.5%. At the fiber center region with only 2.2% air fill-fraction, Anderson localization disappeared. However, we observed Anderson localization in fibers with much lower air fill-fraction. In our experiments, random air line fibers with 150, 250 and 350 ?m diameters were fabricated and characterized by scanning electronic microscopy (SEM). Averaged air line diameters were 177, 247 and 387 nm for the 150, 250 and 350 ?m diameter fibers, respectively. Air fill-fraction was also measured at fiber center, middle and edge regions. Beam profiles were imaged into a charge couple device (CCD) and Anderson localization was observed. Unlike the previous research in which Anderson localization was only observed at the fiber edge due to non-uniform air line distribution, we observed Anderson localization within the fiber area with air fill-fraction significantly lower than the previous investigation. This is because with smaller air line diameter our fiber has higher air lines density than the previous report.

Chen, Minghan; Li, Ming-Jun

2014-02-01

13

Quantum correlations in two-particle Anderson localization.  

PubMed

We predict quantum correlations between noninteracting particles evolving simultaneously in a disordered medium. While the particle density follows the single-particle dynamics and exhibits Anderson localization, the two-particle correlation develops unique features that depend on the quantum statistics of the particles and their initial separation. On short time scales, the localization of one particle becomes dependent on whether or not the other particle is localized. On long time scales, the localized particles show oscillatory correlations within the localization length. These effects can be observed in Anderson localization of nonclassical light and ultracold atoms. PMID:21230976

Lahini, Yoav; Bromberg, Yaron; Christodoulides, Demetrios N; Silberberg, Yaron

2010-10-15

14

Anderson localization in metamaterials and other complex media (Review Article)  

NASA Astrophysics Data System (ADS)

This is a review of some recent (mostly ours) results on Anderson localization of light and electron waves in complex disordered systems, including: (i) left-handed metamaterials, (ii) magnetoactive optical structures, (iii) graphene superlattices, and (iv) nonlinear dielectric media. First, we demonstrate that left-handed metamaterials can significantly suppress localization of light and lead to an anomalously enhanced transmission. This suppression is essential at the long-wavelength limit in the case of normal incidence, at specific angles of oblique incidence (Brewster anomaly), and in vicinity of zero-? or zero-? frequencies for dispersive metamaterials. Remarkably, in disordered samples comprised of alternating normal and left-handed metamaterials, the reciprocal Lyapunov exponent and reciprocal transmittance increment can differ from each other. Second, we study magnetoactive multilayered structures, which exhibit nonreciprocal localization of light depending on the direction of propagation and on polarization. At resonant frequencies or realizations such nonreciprocity results in effectively unidirectional transport of light. Third, we discuss the analogy between wave propagation through multilayered samples with metamaterials and charge transport in graphene, which provides a simple physical explanation of unusual conductive properties of disordered graphene superlatices. We predict disorder-induced resonance of the transmission coefficient at oblique incidence of Dirac quasiparticles. Finally, we demonstrate that an interplay of nonlinearity and disorder in dielectric media can lead to bistability of individual localized states excited inside the medium at resonant frequencies. This results in nonreciprocity of wave transmission and unidirectional transport of light.

Gredeskul, Sergey A.; Kivshar, Yuri S.; Asatryan, Ara A.; Bliokh, Konstantin Y.; Bliokh, Yuri P.; Freilikher, Valentin D.; Shadrivov, Ilya V.

2012-07-01

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

Anderson Localization for Time Quasi Periodic Random Sch\\\\\\  

Microsoft Academic Search

We prove that at large disorder, with large probability and for a set of\\u000aDiophantine frequencies of large measure, Anderson localization in $\\\\Bbb Z^d$\\u000ais {\\\\it stable} under localized time-quasi-periodic perturbations by proving\\u000athat the associated quasi-energy operator has pure point spectrum. The main\\u000atools are the Fr\\\\\\

Jean Bourgain; Wei-Min Wang

2002-01-01

17

Superfluidity versus Anderson Localization in a Dilute Bose Gas  

SciTech Connect

We consider the motion of a quasi-one-dimensional beam of Bose-Einstein condensed particles in a disordered region of finite extent. Interaction effects lead to the appearance of two distinct regions of stationary flow. One is subsonic and corresponds to superfluid motion. The other one is supersonic and dissipative and shows Anderson localization. We compute analytically the interaction-dependent localization length. We also explain the disappearance of the supersonic stationary flow for large disordered samples.

Paul, T.; Leboeuf, P.; Pavloff, N. [Laboratoire de Physique Theorique et Modeles Statistiques, CNRS, Universite Paris Sud, UMR8626, 91405 Orsay Cedex (France); Schlagheck, P. [Institut fuer Theoretische Physik, Universitaet Regensburg, 93040 Regensburg (Germany)

2007-05-25

18

Many-body Anderson localization in one-dimensional systems  

NASA Astrophysics Data System (ADS)

We show, using quasi-exact numerical simulations, that Anderson localization in a disordered one-dimensional potential survives in the presence of attractive interaction between particles. The localization length of the particles' center of mass—computed analytically for weak disorder—is in good agreement with the quasi-exact numerical observations using the time evolving block decimation algorithm. Our approach allows for simulation of the entire experiment including the final measurement of all atom positions.

Delande, Dominique; Sacha, Krzysztof; P?odzie?, Marcin; Avazbaev, Sanat K.; Zakrzewski, Jakub

2013-04-01

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

Super-diffusion in optical realizations of Anderson localization  

NASA Astrophysics Data System (ADS)

We discuss the dynamics of particles in one dimension in potentials that are random in both space and time. The results are applied to recent optics experiments on Anderson localization, in which the transverse spreading of a beam is suppressed by random fluctuations in the refractive index. If the refractive index fluctuates along the direction of the paraxial propagation of the beam, the localization is destroyed. We analyze this broken localization in terms of the spectral decomposition of the potential. When the potential has a discrete spectrum, the spread is controlled by the overlap of Chirikov resonances in phase space. As the number of Fourier components is increased, the resonances merge into a continuum, which is described by a Fokker-Planck equation. We express the diffusion coefficient in terms of the spectral intensity of the potential. For a general class of potentials that are commonly used in optics, the solutions to the Fokker-Planck equation exhibit anomalous diffusion in phase space, implying that when Anderson localization is broken by temporal fluctuations of the potential, the result is transport at a rate similar to a ballistic one or even faster. For a class of potentials which arise in some existing realizations of Anderson localization, atypical behavior is found.

Krivolapov, Yevgeny; Levi, Liad; Fishman, Shmuel; Segev, Mordechai; Wilkinson, Michael

2012-04-01

21

Anderson localization and the theory of dirty superconductors  

NASA Technical Reports Server (NTRS)

A study is made of the effect of Anderson localization in dirty superconductors. The scale dependence of the diffusion in the vicinity of the mobility edge results in a strong renormalization of the zero-temperature coherence length. This implies the breakdown of the Ginzburg criterion close to the metal-insulator transition and thus the importance of fluctuations in this regime. The upper critical field is calculated, and possible experiments are also discussed.

Kapitulnik, A.; Kotliar, G.

1985-01-01

22

Diagrammatic approach to Anderson localization in the quantum kicked rotator  

NASA Astrophysics Data System (ADS)

The phenomenon of Anderson localization in the quantum kicked rotator is analyzed by means of concepts which were originally introduced in condensed matter physics. A diagrammatic language similar to the impurity diagram technique employed in the theory of disordered conductors is developed. The method is applied to a calculation of the quantum return probability and leads to results which coincide (apart from numerical factors) with recent numerical findings.

Altland, Alexander

1993-07-01

23

Anderson Localization for a Multidimensional Model Including Long Range Potentials and Displacements  

NASA Astrophysics Data System (ADS)

We give a short summary on how to combine and extend results of Combes and Hislop [2] (short range Anderson model with additional displacements), Kirsch, Stollmann and Stolz [13] and [14] (long range Anderson model without displacements) to get localization in an energy interval above the infimum of the almost sure spectrum for a continuous multidimensional Anderson model including long range potentials and displacements.

Zenk, Heribert

24

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

25

Anderson Localization: Dynamical Cluster Approximation - Typical Medium Theory Perspective  

NASA Astrophysics Data System (ADS)

Mean field theories like the coherent potential approximation (CPA) and its cluster extensions, including the dynamical cluster approximation (DCA), fail to describe the Anderson localization transition in disordered systems. This failure is intrinsic to these theories as the algebraically averaged quantities used in them always favor the metallic state, and hence cannot describe the localization transition. Here we extend the Typical Medium Theory (TMT), which replaces the average quantities with their corresponding typical (geometrically averaged) equivalents, to its cluster form such that non-local correlations can be incorporated systematically. We apply our method to study the localization phenomena in various dimensions. Such an approach opens a new avenue to study localization effect both in model and in real materials.

Ekuma, Chinedu; Meng, Ziyang; Terletska, Hanna; Moreno, Juana; Jarrell, Mark; Dobrosavljevic, Vladimir

2013-03-01

26

Fractional moment methods for Anderson localization with SAW representation  

NASA Astrophysics Data System (ADS)

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

Suzuki, Fumika

2013-03-01

27

Localization and mobility gap in the topological Anderson insulator  

NASA Astrophysics Data System (ADS)

It has been proposed that disorder may lead to a new type of topological insulator, called the topological Anderson insulator (TAI). Here we examine the physical origin of this phenomenon. We calculate the topological invariants and density of states of the disordered model in a supercell of a two-dimensional HgTe/CdTe quantum well. The topologically nontrivial phase is triggered by a band touching as the disorder strength increases. The TAI is protected by a mobility gap, in contrast to the band gap in conventional quantum spin Hall systems. The mobility gap in the TAI consists of a cluster of nontrivial subgaps separated by almost flat and localized bands.

Zhang, Yan-Yang; Chu, Rui-Lin; Zhang, Fu-Chun; Shen, Shun-Qing

2012-01-01

28

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

29

Analysis of Anderson localization of light in GaN nanocolumns  

Microsoft Academic Search

In disordered materials, the combination of multiple light scattering and optical interference induces the localization of light. This phenomenon is called Anderson localization which is widely observed in electron systems with random potentials. Experimental studies of Anderson localization of light have been performed over the last three decades [I]. However, most of those studies attempted to secure the evidence of

Masaru Sakai; Yuta Inose; Tomi Ohtsuki; Kazuhiro Ema; Akihiko Kikuchi; Katsumi Kishino

2011-01-01

30

Anderson localized modes in a disordered glass optical fiber  

NASA Astrophysics Data System (ADS)

A beam of light can propagate in a time-invariant transversely disordered waveguide because of transverse Anderson localization. We developed a disordered glass optical ber from a porous artisan glass (satin quartz). The refractive index pro le of the disordered glass optical ber is composed of a non-uniform distribution of air voids which can be approximated as longitudinally invariant. The ll-fraction of air voids is higher at the regions closer to the boundary compared with the central regions. The experimental results show that the beam radius of a localized beam is smaller at the regions closer to the boundary than the one at the central regions. In order to understand the reason behind these observations, the fully vectorial modes of the disordered glass ber are calculated using the actual scanning electron microscope image of the ber tip. The numerical calculations show that the modes at regions closer to the boundary of the ber are more localized compared with the modes at the central regions. Coupling of an input beam to the less-localized modes with large tails at the central regions of the ber results in a large beam radius. In comparison, a beam of light launched at the regions close to the boundary couples to the highly compact modes of the ber and results in a small localized beam radius.

Karbasi, Salman; Hosseini, Seyedrasoul; Koch, Karl W.; Hawkins, Thomas; Ballato, John; Mafi, Arash

2014-02-01

31

Image transport using Anderson localized modes in disordered optical fibers  

NASA Astrophysics Data System (ADS)

An optical fiber with a transversely disordered yet longitudinally invariant refractive index profile can propagate a beam of light using transverse Anderson localization. A launched beam of light into the disordered optical fiber expands till it reaches its localization radius beyond which it propagates without further expansion. In contrast to a conventional single-core optical fiber in which a propagating beam of light can only couple to and propagate in the core, the beam of light can be coupled to any point at the tip of the disordered fiber. This property originated from the localized highly multimodal property of disordered optical fibers that can be used for high quality optical image transport. We experimentally compare the quality of the transported images in the disordered polymer optical fibers with those transported through the multicore imaging fibers, as well as conventional single core fibers. The impacts of source wavelength and refractive index difference between the disordered sites on the quality of the transported images in the disordered optical fibers is studied numerically. The role of randomness in improving the quality of transported images is investigated by comparing the full vectorial modes of a disordered fiber with those in a periodic multicore fiber.

Karbasi, Salman; Frazier, Ryan J.; Koch, Karl W.; Hawkins, Thomas; Ballato, John; Mafi, Arash

2014-03-01

32

Anderson Localization for Schrödinger Operators on with Strongly Mixing Potentials  

NASA Astrophysics Data System (ADS)

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

Bourgain, Jean; Schlag, Wilhelm

33

Variational theory of valence fluctuations: Ground states and quasiparticle excitations of the Anderson lattice model  

SciTech Connect

A variational study of ground states of the orbitally nondegenerate Anderson lattice model, using a wave function with one variational parameter per Bloch state k, has been extended to deal with essentially metallic systems having a nonintegral number of electrons per site. Quasiparticle excitations are obtained by direct appeal to Landau's original definition for interacting Fermi liquids, scrE/sub qp/(k,sigma) = deltaE/sub total//deltan qp(k,sigma).

Brandow, B.H.

1986-01-01

34

Anderson localization in optical waveguide arrays with off-diagonal coupling disorder.  

PubMed

We report on the observation of Anderson wave localization in one-dimensional waveguide arrays with off-diagonal disorder. The waveguide elements are inscribed in silica glass, and a uniform random distribution of coupling parameters is achieved by a precise variation of the relative waveguide positions. In the absence of disorder we observe ballistic transport as expected from discrete diffraction in periodic arrays. When off-diagonal disorder is deliberately introduced into the array we observe Anderson localization. The strength of the localization signature increases with higher levels of disorder. PMID:21747520

Martin, Lane; Di Giuseppe, Giovanni; Perez-Leija, Armando; Keil, Robert; Dreisow, Felix; Heinrich, Matthias; Nolte, Stefan; Szameit, Alexander; Abouraddy, Ayman F; Christodoulides, Demetrios N; Saleh, Bahaa E A

2011-07-01

35

Simulating Anderson localization via a quantum walk on a one-dimensional lattice of superconducting qubits  

NASA Astrophysics Data System (ADS)

Quantum walk (QW) on a disordered lattice leads to a multitude of interesting phenomena, such as Anderson localization. While QW has been realized in various optical and atomic systems, its implementation with superconducting qubits still remains pending. The major challenge in simulating QW with superconducting qubits emerges from the fact that on-chip superconducting qubits cannot hop between two adjacent lattice sites. Here we overcome this barrier and develop a gate-based scheme to realize the discrete time QW by placing a pair of qubits on each site of a one-dimensional (1D) lattice and treating an excitation as a walker. It is also shown that various lattice disorders can be introduced and fully controlled by tuning the qubit parameters in our quantum walk circuit. We observe a distinct signature of transition from the ballistic regime to a localized QW with an increasing strength of disorder. Finally, an eight-qubit experiment is proposed where the signatures of such localized and delocalized regimes can be detected with existing superconducting technology. Our proposal opens up the possibility of exploring various quantum transport processes with promising superconducting qubits.

Ghosh, Joydip

2014-02-01

36

Observation of Migrating Transverse Anderson Localizations of Light in Nonlocal Media  

NASA Astrophysics Data System (ADS)

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

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

2014-05-01

37

Observation of migrating transverse anderson localizations of light in nonlocal media.  

PubMed

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

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

2014-05-16

38

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

SciTech Connect

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

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); Belic, Milivoj R. [Texas A and M University at Qatar, P. O. Box 23874, Doha (Qatar)

2010-02-15

39

Localized excitations and their thresholds  

PubMed

We propose a numerical method for identifying localized excitations in discrete nonlinear Schrodinger type models. This methodology, based on the application of a nonlinear iterative version of the Rayleigh-Ritz variational principle yields breather excitations in a very fast and efficient way in one or higher spatial dimensions. The typical convergence properties of the method are found to be super-linear. The usefulness of this technique is illustrated by studying the properties of the recently developed theoretical criteria for the excitation power thresholds for nonlinear modes. PMID:11088275

Kevrekidis; Rasmussen; Bishop

2000-04-01

40

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

41

Anderson Localization for a Multi-Particle Quantum Graph  

NASA Astrophysics Data System (ADS)

We study a multi-particle quantum graph with random potential. Taking the approach of multiscale analysis, we prove exponential and strong dynamical localization of any order in the Hilbert-Schmidt norm near the spectral edge. Apart from the results on multi-particle systems, we also prove Lifshitz-type asymptotics for single-particle systems. This shows in particular that localization for single-particle quantum graphs holds under a weaker assumption on the random potential than previously known.

Sabri, Mostafa

2014-11-01

42

Linear and Nonlinear Anderson Localization in a Curved Potential  

NASA Astrophysics Data System (ADS)

Disorder induced localization in the presence of nonlinearity and curvature is investigated. The time-resolved three-dimensional expansion of a wave packet in a bent cigar shaped potential with a focusing Kerr-like interaction term and Gaussian disorder is numerically analyzed. A self-consistent analytical theory, in which randomness, nonlinearity and geometry are determined by a single scaling parameter, is reported, and it is shown that curvature enhances localization.

Claudio, Conti

2014-03-01

43

Light focusing in the Anderson regime.  

PubMed

Anderson localization is a regime in which diffusion is inhibited and waves (also electromagnetic waves) get localized. Here we exploit adaptive optics to achieve focusing in disordered optical fibres in the Anderson regime. By wavefront shaping and optimization, we observe the generation of a propagation-invariant beam, where light is trapped transversally by disorder, and show that Anderson localizations can be also excited by extended speckled beams. We demonstrate that disordered fibres allow a more efficient focusing action with respect to standard fibres in a way independent of their length, because of the propagation-invariant features and cooperative action of transverse localizations. PMID:25072204

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

2014-01-01

44

The Anderson localization problem, the Fermi–Pasta–Ulam paradox and the generalized diffusion approach  

Microsoft Academic Search

The goal of this paper is twofold. First, based on the interpretation of a quantum tight-binding model in terms of a classical Hamiltonian map, we consider the Anderson localization (AL) problem as the Fermi–Pasta–Ulam (FPU) effect in a modified dynamical system containing both stable and unstable (inverted) modes. Delocalized states in the AL are analogous to the stable quasi-periodic motion

V N Kuzovkov

2011-01-01

45

The Fermi-Pasta-Ulam paradox, Anderson Localization problem and the generalized diffusion approach  

Microsoft Academic Search

The goal of this paper is two-fold. First, based on the interpretation of a quantum tight-binding model in terms of a classical Hamiltonian map, we consider the Anderson localization (AL) problem as the Fermi-Pasta-Ulam (FPU) effect in a modified dynamical system containing both stable and unstable (inverted) modes. Delocalized states in the AL are analogous to the stable quasi-periodic motion

V. N. Kuzovkov

2008-01-01

46

Conductance fluctuation of edge-disordered graphene nanoribbons: Crossover from diffusive transport to Anderson localization  

NASA Astrophysics Data System (ADS)

Conductance fluctuation of edge-disordered graphene nanoribbons (ED-GNRs) is examined using the non-equilibrium Green's function technique combined with the extended Hückel approximation. The mean free path ? and the localization length ? of the ED-GNRs are determined to classify the quantum transport regimes. In the diffusive regime where the length Lc of the ED-GNRs is much longer than ? and much shorter than ?, the conductance histogram is given by a Gaussian distribution function with universal conductance fluctuation. In the localization regime where Lc??, the histogram is no longer the universal Gaussian distribution but a lognormal distribution that characterizes Anderson localization.

Takashima, Kengo; Yamamoto, Takahiro

2014-03-01

47

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

48

The Fermi-Pasta-Ulam paradox, Anderson Localization problem and the generalized diffusion approach  

Microsoft Academic Search

The goal of this paper is two-fold. First, based on the interpretation of a\\u000aquantum tight-binding model in terms of a classical Hamiltonian map, we\\u000aconsider the Anderson localization (AL) problem as the Fermi-Pasta-Ulam (FPU)\\u000aeffect in a modified dynamical system containing both stable and unstable\\u000a(inverted) modes. Delocalized states in the AL are analogous to the stable\\u000aquasi-periodic motion

V. N. Kuzovkov

2008-01-01

49

Measurement-based tailoring of Anderson localization of partially coherent light  

NASA Astrophysics Data System (ADS)

We put forward an experimental configuration to observe transverse Anderson localization of partially coherent light beams with a tunable degree of first-order coherence. The scheme makes use of entangled photons propagating in disordered waveguide arrays and is based on the unique relationship between the degree of entanglement of a pair of photons and the coherence properties of the individual photons constituting the pair. The scheme can be readily implemented with current waveguide-on-a-chip technology, and surprisingly the tunability of the coherence properties of the individual photons is done at the measurement stage, without resorting to changes of the light source itself.

Svozilík, Ji?í; Pe?ina, Jan; Torres, Juan P.

2014-05-01

50

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

51

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

52

The Anderson localization problem, the Fermi-Pasta-Ulam paradox and the generalized diffusion approach  

NASA Astrophysics Data System (ADS)

The goal of this paper is twofold. First, based on the interpretation of a quantum tight-binding model in terms of a classical Hamiltonian map, we consider the Anderson localization (AL) problem as the Fermi-Pasta-Ulam (FPU) effect in a modified dynamical system containing both stable and unstable (inverted) modes. Delocalized states in the AL are analogous to the stable quasi-periodic motion in FPU, whereas localized states are analogous to thermalization, respectively. The second aim is to use the classical Hamilton map for a simplified derivation of exact equations for the localization operator H(z). The latter was presented earlier (Kuzovkov et al 2002 J. Phys.: Condens. Matter 14 13777) treating the AL as a generalized diffusion in a dynamical system. We demonstrate that counter-intuitive results of our studies of the AL are similar to the FPU counter-intuitivity.

Kuzovkov, V. N.

2011-12-01

53

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

54

Tunable Anderson Localization in Hydrogenated Graphene Based on the Electric Field Effect  

NASA Astrophysics Data System (ADS)

Effective control of hydrogenation of graphene is of great scientific and technological importance. However, the reversible control of H density (nH) on graphene is difficult due to the irreversible H2 formation of the detached H adatoms. Here we present a novel mechanism for controlling nH by using the unique proton transfer reaction between NH3 gas and hydrogenated graphene, which can be tuned by applying perpendicular electric fields. Using first-principles calculations, we show that nH can be reversibly tuned by the applied electric fields around the critical density for the Anderson localization in hydrogenated graphene. The proposed field-induced control of H adsorption or desorption on graphene opens a path toward the development of new graphene transistors based on the tunable degree of disorder.

Kang, Joongoo; Wei, Su-Huai

2013-11-01

55

Dynamical mean field theories, Anderson localization and a quantum critical point  

NASA Astrophysics Data System (ADS)

We investigate extended dynamical mean field theory (EDMFT) of the interacting Bose-Fermi system using quasiclassical approximation on the impurity solver. We compare semiclassical results to the exact Quantum Monte Carlo (QMC) solution and find a good agreement in a range of parameters. Taking the classical limit we prove that the transition to the ordered phase is of the first order in any dimension below four. Using the functional formulation of EDMFT we derive a criterion for the instability of the disordered phase. We explain how DMFT and extended DMFT approximations can be formulated in the parquet equation language. A natural extension, based on the parquet formalism, is proposed to incorporate nonlocal particle particle and particle hole fluctuations. We also revisited Anderson localization problem and clarified few unclear aspects.

Pankov, Sergey V.

56

Nonuniversal Intensity Correlations in a Two-Dimensional Anderson-Localizing Random Medium  

NASA Astrophysics Data System (ADS)

Complex dielectric media often appear opaque because light traveling through them is scattered multiple times. Although the light scattering is a random process, different paths through the medium can be correlated encoding information about the medium. Here, we present spectroscopic measurements of nonuniversal intensity correlations that emerge when embedding quantum emitters inside a disordered photonic crystal that is found to Anderson-localize light. The emitters probe in situ the microscopic details of the medium, and imprint such near-field properties onto the far-field correlations. Our findings provide new ways of enhancing light-matter interaction for quantum electrodynamics and energy harvesting, and may find applications in subwavelength diffuse-wave spectroscopy for biophotonics.

García, Pedro David; Stobbe, Søren; Söllner, Immo; Lodahl, Peter

2012-12-01

57

Nonreciprocal Anderson localization in one-dimensional ternary disordered media containing magnetized plasma layers  

NASA Astrophysics Data System (ADS)

This paper proposes a one-dimensional random structure composed of three types of alternating layers of dielectric and magnetized plasma materials. By employing the transfer matrix method, the localization lengths of the waves propagating in opposite directions are calculated. The numerical results demonstrate that nonreciprocal features appear in the averaged localization length and individual transmission resonances. However, in the short wavelength regime, the nonreciprocal behavior of the averaged localization length disappears, and the maximum of differential transmission decreases. The author investigates the effects of the external magnetic field, incident angle, collision frequency, and plasma density of the plasma layer on the reciprocal properties. The frequencies at which nonreciprocity occurs depend on the external magnetic field. Thus, it is possible to realize a photonic diode that is tunable with the external magnetic field. Also found is that for small angles of incidence no significant difference exists between the localization lengths of the forward and backward waves. There is a lower limit for the plasma density of the magnetized plasma layers to obtain nonreciprocal Anderson localization. As the collision frequency increases, the nonreciprocal features of the proposed random system survive.

Ghasempour Ardakani, Abbas

2014-06-01

58

Superconductivity in the generalized periodic Anderson model with strong local attraction  

SciTech Connect

We study a generalized periodic Anderson model with on-site hybridization between wide- and narrow-band electrons and strong and local coupling with the lattice deformation. Provided that the interaction with the lattice is strong enough, the narrow-band electrons will be turned into small polarons which interact attractively with each other over short distances, leading to the formation of local pairs of narrow-band electrons. This leads to a pinning of the Fermi level which is due to the fact that narrow-band electrons exist only in pair states. By means of a generalized Schrieffer-Wolff transformation we eliminate hybridization and obtain an effective Hamiltonian which describes a contact interaction between local pairs and wide-band electrons as well as the direct hopping of local pairs and interparticle Coulomb interactions. In such a system the two types of mechanisms which can lead to superconductivity have been studied. The first one is due to direct local pair hopping and involves exclusively the narrow-band subsystem giving rise to a superconductivity analogous to superfluidity in /sup 4/He. The second one is due to a contact interaction between local pairs and pairs of wide-band electrons. This leads to a superconducting state involving both subsystems where the local pairs of the narrow-band subsystem induce Cooper pairing amongst the electrons of the wide-band subsystem. Consequently, the single-particle spectrum of the wide-band electrons opens up a gap around the position of the narrow band of electrons in pair states.

Robaszkiewicz, S.; Micnas, R.; Ranninger, J.

1987-07-01

59

Electronic excitation spectra of the five-orbital Anderson impurity model: From the atomic limit to itinerant atomic magnetism  

NASA Astrophysics Data System (ADS)

We study the competition of Coulomb interaction and hybridization effects in the five-orbital Anderson impurity model by means of continuous time quantum Monte Carlo, exact diagonalization, and Hartree-Fock calculations. The dependence of the electronic excitation spectra and thermodynamic ground-state properties on the hybridization strength and the form of the Coulomb interaction is systematically investigated for impurity occupation number N ?6. With increasing hybridization strength, a Kondo resonance emerges, broadens and merges with some of the upper and lower Hubbard peaks. Concomitantly, there is an increase of charge fluctuations at the impurity site. In contrast to the single-orbital model, some atomic multiplet peaks and exchange split satellites persist despite strong charge fluctuations. We find that Hund's coupling leads to a state that may be characterized as an itinerant single atom magnet. As the filling is increased, the magnetic moment decreases, but the spin freezing phenomenon persists up to N ?8. When the hybridization is weak, the positions of atomic ionization peaks are rather sensitive to shifts of the impurity on-site energies. This allows to distinguish atomic ionization peaks from quasiparticle peaks or satellites in the electronic excitation spectra. On the methodological side we show that a comparison between the spectra obtained from Monte Carlo and exact diagonalization calculations is possible if the charge fluctuations are properly matched.

Huang, Li; Wehling, Tim O.; Werner, Philipp

2014-06-01

60

Local and average fields inside surface-disordered waveguides: Resonances in the one-dimensional Anderson localization regime  

NASA Astrophysics Data System (ADS)

We investigate the one-dimensional propagation of waves in the Anderson localization regime, for a single-mode, surface disordered waveguide. We make use of both an analytical formulation and rigorous numerical simulation calculations. The occurrence of anomalously large transmission coefficients for given realizations and/or frequencies is studied, revealing huge field intensity concentration inside the disordered waveguide. The analytically predicted dependence of the average intensity, being in good agreement with the numerical results for moderately long systems, fails to explain the intensity distribution observed deep in the localized regime. The average contribution to the field intensity from the resonances that are above a threshold transmission coefficient Tc is a broad distribution with a large maximum at/near mid-waveguide, depending universally (for a given Tc) on the ratio of the length of the disorder segment to the localization length, L/?. The same universality is observed in the spatial distribution of the intensity inside typical (nonresonant with respect to the transmission coefficient) realizations, presenting a shape similar to that of the total average intensity, but with a faster decay. Evidence is given of the self-averaging nature of the random quantity ln[I(x)]/x?-1/?. Higher-order moments of the intensity are also shown.

Sánchez-Gil, José A.; Freilikher, Valentin

2003-08-01

61

Local structural excitations in model glasses  

NASA Astrophysics Data System (ADS)

Structural excitations of model Lennard-Jones glass systems are investigated using the activation-relaxation technique (ARTn), which explores the potential energy landscape around a local minimum energy configuration by converging to a nearby saddle-point configuration. Performing ARTn results in a distribution of barrier energies that is single-peaked for well-relaxed samples. The present work characterizes such atomic-scale excitations in terms of their local structure and environment. It is found that, at zero applied stress, many of the identified events consist of chainlike excitations that can either be extended or ringlike in their geometry. The location and barrier energy of these saddle-point structures are found to correlate with the type of atom involved, and with spatial regions that have low Kelvin eigenshear moduli and are close to the excess free volume within the configuration. Such correlations are, however, weak and more generally the identified local structural excitations are seen to exist throughout the model glass sample. The work concludes with a discussion within the framework of ? and ? relaxation processes that are known to occur in the undercooled liquid regime.

Swayamjyoti, S.; Löffler, J. F.; Derlet, P. M.

2014-06-01

62

Calculation of the spectral dependence of the Anderson localization criterion in a one-dimensional system with correlated diagonal disorder  

NASA Astrophysics Data System (ADS)

We consider the problem of calculating the Anderson criterion for a one-dimensional disordered chain with correlated disorder. We solve this problem by the perturbation method with the inverse correlation length as the small parameter. We show that in a correlated system, the degree of localization not only naturally decreases but its spectral dependence also differs significantly from the spectral dependence in uncorrelated chains. The calculations are based on the method for constructing joint statistics of Green's functions, which was previously used to analyze uncorrelated one-dimensional systems. We illustrate the theoretical calculations with a numerical experiment.

Kozlov, G. G.

2014-04-01

63

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

64

Giant Fluctuations of Local Magnetoresistance of Organic Spin Valves and the Non-Hermitian 1D Anderson Model.  

PubMed

Motivated by recent experiments, where the tunnel magnetoresitance (TMR) of a spin valve was measured locally, we theoretically study the distribution of TMR along the surface of magnetized electrodes. We show that, even in the absence of interfacial effects (like hybridization due to donor and acceptor molecules), this distribution is very broad, and the portion of area with negative TMR is appreciable even if on average the TMR is positive. The origin of the local sign reversal is quantum interference of subsequent spin-rotation amplitudes in the course of incoherent transport of carriers between the source and the drain. We find the distribution of local TMR exactly by drawing upon formal similarity between evolution of spinors in time and of the reflection coefficient along a 1D chain in the Anderson model. The results obtained are confirmed by the numerical simulations. PMID:24949781

Roundy, R C; Nemirovsky, D; Kagalovsky, V; Raikh, M E

2014-06-01

65

Giant Fluctuations of Local Magnetoresistance of Organic Spin Valves and the Non-Hermitian 1D Anderson Model  

NASA Astrophysics Data System (ADS)

Motivated by recent experiments, where the tunnel magnetoresitance (TMR) of a spin valve was measured locally, we theoretically study the distribution of TMR along the surface of magnetized electrodes. We show that, even in the absence of interfacial effects (like hybridization due to donor and acceptor molecules), this distribution is very broad, and the portion of area with negative TMR is appreciable even if on average the TMR is positive. The origin of the local sign reversal is quantum interference of subsequent spin-rotation amplitudes in the course of incoherent transport of carriers between the source and the drain. We find the distribution of local TMR exactly by drawing upon formal similarity between evolution of spinors in time and of the reflection coefficient along a 1D chain in the Anderson model. The results obtained are confirmed by the numerical simulations.

Roundy, R. C.; Nemirovsky, D.; Kagalovsky, V.; Raikh, M. E.

2014-06-01

66

Localized excitations in UPdSn  

SciTech Connect

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

Nakotte, H.; Robinson, R.A.; Swan, T.; Kelley, T. [Los Alamos National Lab., NM (United States). Manuel Lujan Jr. Neutron Scattering Center; Bull, M. [Univ. of London (United Kingdom)]|[Univ. of Amsterdam (Netherlands). Van der Waals-Zeeman Inst.; McEwen, K.A. [Univ. of London (United Kingdom); Ecclestone, R.A. [Rutherford Appleton Lab., Chilton (United Kingdom). ISIS Div.; Brueck, E. [Univ. of Amsterdam (Netherlands). Van der Waals-Zeeman Inst.

1997-11-01

67

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)] [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)] [IBM Research Division, Zurich Research Laboratory, CH-8803 Rueschlikon (Switzerland)

1997-02-01

68

Magnetoresistance of an Anderson Insulator of Bosons  

NASA Astrophysics Data System (ADS)

We study the magnetoresistance of two-dimensional bosonic Anderson insulators. We describe the change in spatial decay of localized excitations in response to a magnetic field, which is given by an interference sum over alternative tunneling trajectories. The excitations become more localized with increasing field (in sharp contrast to generic fermionic excitations which get weakly delocalized): the localization length ?(B) is found to change as ?-1(B)-?-1(0)˜B4/5. The quantum interference problem maps onto the classical statistical mechanics of directed polymers in random media (DPRM). We explain the observed scaling using a simplified droplet model which incorporates the nontrivial DPRM exponents. Our results have implications for a variety of experiments on magnetic-field-tuned superconductor-to-insulator transitions observed in disordered films, granular superconductors, and Josephson junction arrays, as well as for cold atoms in artificial gauge fields.

Gangopadhyay, Anirban; Galitski, Victor; Müller, Markus

2013-07-01

69

Disordered Josephson junction chains: Anderson localization of normal modes and impedance fluctuations  

NASA Astrophysics Data System (ADS)

We study the properties of the normal modes of a chain of Josephson junctions in the simultaneous presence of disorder and absorption. We consider the superconducting regime of small phase fluctuations and focus on the case where the effects of disorder and absorption can be treated additively. We analyze the frequency shift and the localization length of the modes. We also calculate the distribution of the frequency-dependent impedance of the chain. The distribution is Gaussian if the localization length is long compared to the absorption length, while it has a power-law tail in the opposite limit.

Basko, D. M.; Hekking, F. W. J.

2013-09-01

70

Quantum transport in chemically modified two-dimensional graphene: From minimal conductivity to Anderson localization  

NASA Astrophysics Data System (ADS)

An efficient computational methodology is used to explore charge transport properties in chemically modified (and randomly disordered) graphene-based materials. The Hamiltonians of various complex forms of graphene are constructed using tight-binding models enriched by first-principles calculations. These atomistic models are further implemented into a real-space order-N Kubo-Greenwood approach, giving access to the main transport length scales (mean free paths, localization lengths) as a function of defect density and charge carrier energy. An extensive investigation is performed for epoxide impurities with specific discussions on both the existence of a minimum semiclassical conductivity and a crossover between weak to strong localization regime. The 2D generalization of the Thouless relationship linking transport length scales is here illustrated based on a realistic disorder model.

Leconte, N.; Lherbier, A.; Varchon, F.; Ordejon, P.; Roche, S.; Charlier, J.-C.

2011-12-01

71

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

SciTech Connect

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

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

2001-10-31

72

Anderson localization in two-dimensional graphene with short-range disorder: One-parameter scaling and finite-size effects  

NASA Astrophysics Data System (ADS)

We study Anderson localization in graphene with short-range disorder using the real-space Kubo-Greenwood method implemented on graphics processing units. Two models of short-range disorder, namely, the Anderson on-site disorder model and the vacancy defect model, are considered. For graphene with Anderson disorder, localization lengths of quasi-one-dimensional systems with various disorder strengths, edge symmetries, and boundary conditions are calculated using the real-space Kubo-Greenwood formalism, showing excellent agreement with independent transfer matrix calculations and superior computational efficiency. Using these data, we demonstrate the applicability of the one-parameter scaling theory of localization length and propose an analytical expression for the scaling function, which provides a reliable method of computing the two-dimensional localization length. This method is found to be consistent with another widely used method which relates the two-dimensional localization length to the elastic mean free path and the semiclassical conductivity. Abnormal behavior at the charge neutrality point is identified and interpreted to be caused by finite-size effects when the system width is comparable to or smaller than the elastic mean free path. We also demonstrate the finite-size effect when calculating the two-dimensional conductivity in the localized regime and show that a renormalization group ? function consistent with the one-parameter scaling theory can be extracted numerically. For graphene with vacancy disorder, we show that the proposed scaling function of localization length also applies. Last, we discuss some ambiguities in calculating the semiclassical conductivity around the charge neutrality point due to the presence of resonant states.

Fan, Zheyong; Uppstu, Andreas; Harju, Ari

2014-06-01

73

The Anderson Current Loop  

NASA Technical Reports Server (NTRS)

Four-wire-probe concept applied to electrical-resistance transducers. Anderson current loop is excitation-and-signal-conditioning circuit suitable for use with strain gauges, resistance thermometers, and other electrical-resistance transducers mounted in harsh environments. Used as alternative to Wheatstone bridge. Simplifies signal-conditioning problem, enabling precise measurement of small changes in resistance of transducer. Eliminates some uncertainties in Wheatstone-bridge resistance-change measurements in flight research. Current loop configuration makes effects of lead-wire and contact resistances insignificantly small. Also provides output voltage that varies linearly with change in gauge resistance, and does so at double sensitivity of Wheatstone bridge.

Anderson, Karl F.

1994-01-01

74

Localized excitations in amorphous silicon alloys  

SciTech Connect

The valence band edge of a-Si:H is sensitive to H content, while the conduction band edge is not. The optical gap increases 50% going from the isolated SiH group to the polysilane configuration; the smallest energy gap was for the polycrystal models for a-Si:H. Only the complexes involving the Si dangling bond give rise to active states deep in he a-Si fundamental energy gap. Positions of dangling bond defect state agree with photoluminescence of undoped and oxidized a-Si:H films. Incorporation of halogens into a-Si:H increases the optical gap, quasi-localized states near conduction band tail, and resonances deep in the valence band. Carbon increases the optical gap and produces resonances deep in both bands, while tin does not increase the optical gap and produces resonances in upper part of a-Si:H valence band; this is consistent with a model based on relative strength of Si-Si bond to Si-impurity bond. Effects of P dopant are consistent with models based on P in a-Si:H producing dopant-defect pairs, increased Fermi energy, etc. B substitutional dopants (tetrahedral) produces states near the valence band edge which resemble the show impurity levels in crystalline Si. Trigonally bonded B gives rise to states within the a-Si:H fundamental gap. B-H complexes suggest B-H bonds in B-doped a-Si:H, even at low B contents. Figs, 22 refs. (DLC)

Not Available

1987-10-01

75

Intrinsic localized states and nonlinear excitations of Bloch  

Microsoft Academic Search

We address the dynamics of Bloch electrons with Coulomb interaction on a discrete lattice in a electric field. The analysis is based on exact calculations with the inverse scattering method. The results include the intrinsic localized states and nonlinear excitations of Bloch electrons. Such a system can be written as the extended Hubbard model which is relevant to a variety

Wu-Ming Liu; Siu-Tat Chui

2002-01-01

76

Spin pumping by nonreciprocal spin waves under local excitation  

NASA Astrophysics Data System (ADS)

We measured spatial distribution of spin pumping by nonreciprocal magnetostatic surface waves (MSSWs) using inverse spin Hall effect (ISHE) in a YIG/Pt system under local excitation. The local intensity of spin pumping by MSSWs shows center displacement of +/- 0.1 mm from the center of a waveguide according to the reversal of a bias field, which is due to the nonreciprocal propagation of MSSWs over a macroscopic distance. The combination of spin pumping and ISHE enables electrical investigation of local spin dynamics in a magnetic insulator.

Iguchi, R.; Ando, K.; Qiu, Z.; An, T.; Saitoh, E.; Sato, T.

2013-01-01

77

Imaging Ultrafast Demagnetization Dynamics after a Spatially Localized Optical Excitation  

NASA Astrophysics Data System (ADS)

Ultrashort, coherent x-ray pulses of a free-electron laser are used to holographically image the magnetization dynamics within a magnetic domain pattern after creation of a localized excitation via an optical standing wave. We observe a spatially confined reduction of the magnetization within a couple of hundred femtoseconds followed by its slower recovery. Additionally, the experimental results show evidence of a spatial evolution of magnetization, which we attribute to ultrafast transport of nonequilibrium spin-polarized electrons for early times and to a fluence-dependent remagnetization rate for later times.

von Korff Schmising, C.; Pfau, B.; Schneider, M.; Günther, C. M.; Giovannella, M.; Perron, J.; Vodungbo, B.; Müller, L.; Capotondi, F.; Pedersoli, E.; Mahne, N.; Lüning, J.; Eisebitt, S.

2014-05-01

78

Topological Anderson insulator phenomena  

NASA Astrophysics Data System (ADS)

We study the nature of the disorder-induced quantized conductance, i.e., the phenomena of topological Anderson insulator (TAI). The disorder effect in several different systems where the anomalous Hall effect exists is numerically studied using the tight-binding Hamiltonian. It is found that the TAI phenomena can also exist in the modified Dirac model where the quadratic corrections k2?z are included and the electron-hole symmetry is kept. These phenomena also occur in the graphene system with the next-nearest-neighbor coupling and the staggered sublattice potential. For the graphene sheet with Rashba spin-orbit interaction as well as an exchange field, a precursor of TAI is observed. A comparison between the localization length of the two-dimensional ribbon and two-dimensional cylinder structures clearly reveals the topological nature of these phenomena. Furthermore, analysis on the local current density in anomalous quantum Hall systems where the TAI phenomena may or may not arise reveals the nature of TAI phenomena. In the presence of small disorders, the conductance is not quantized and the bulk and edge states coexist in the system. As disorder strength increases, the bulk state is quickly destroyed, while the robust edge state may survive. When the edge state is robust enough to sustain the strong disorder that completely kills the bulk state, TAI phenomena arise.

Xing, Yanxia; Zhang, Lei; Wang, Jian

2011-07-01

79

Localized nonlinear excitations in diffusive Hindmarsh-Rose neural networks  

NASA Astrophysics Data System (ADS)

We study localized nonlinear excitations in diffusive Hindmarsh-Rose neural networks. We show that the Hindmarsh-Rose model can be reduced to a modified Complex Ginzburg-Landau equation through the application of a perturbation technique. We equally report on the presence of envelop solitons of the nerve impulse in this neural network. From the biological point of view, this result suggests that neurons can participate in a collective processing of information, a relevant part of which is shared over all neurons but not concentrated at the single neuron level. By employing the standard linear stability analysis, the growth rate of the modulational instability is derived as a function of the wave number and systems parameters.

Moukam Kakmeni, F. M.; Inack, E. M.; Yamakou, E. M.

2014-05-01

80

Localized excitations in (2+1)-dimensional systems  

NASA Astrophysics Data System (ADS)

By means of a special variable separation approach, a common formula with some arbitrary functions has been obtained for some suitable physical quantities of various (2+1)-dimensional models such as the Davey-Stewartson (DS) model, the Nizhnik-Novikov-Veselov (NNV) system, asymmetric NNV equation, asymmetric DS equation, dispersive long wave equation, Broer-Kaup-Kupershmidt system, long wave-short wave interaction model, Maccari system, and a general (N+M)-component Ablowitz-Kaup-Newell-Segur (AKNS) system. Selecting the arbitrary functions appropriately, one may obtain abundant stable localized interesting excitations such as the multidromions, lumps, ring soliton solutions, breathers, instantons, etc. It is shown that some types of lower dimensional chaotic patterns such as the chaotic-chaotic patterns, periodic-chaotic patterns, chaotic line soliton patterns, chaotic dromion patterns, fractal lump patterns, and fractal dromion patterns may be found in higher dimensional soliton systems. The interactions between the traveling ring type soliton solutions are completely elastic. The traveling ring solitons pass through each other and preserve their shapes, velocities, and phases. Some types of localized weak solutions, peakons, are also discussed. Especially, the interactions between two peakons are not completely elastic. After the interactions, the traveling peakons also pass through each other and preserve their velocities and phases, however, they completely exchange their shapes.

Tang, Xiao-Yan; Lou, Sen-Yue; Zhang, Ying

2002-10-01

81

Localized excitations in (2+1)-dimensional systems.  

PubMed

By means of a special variable separation approach, a common formula with some arbitrary functions has been obtained for some suitable physical quantities of various (2+1)-dimensional models such as the Davey-Stewartson (DS) model, the Nizhnik-Novikov-Veselov (NNV) system, asymmetric NNV equation, asymmetric DS equation, dispersive long wave equation, Broer-Kaup-Kupershmidt system, long wave-short wave interaction model, Maccari system, and a general (N+M)-component Ablowitz-Kaup-Newell-Segur (AKNS) system. Selecting the arbitrary functions appropriately, one may obtain abundant stable localized interesting excitations such as the multidromions, lumps, ring soliton solutions, breathers, instantons, etc. It is shown that some types of lower dimensional chaotic patterns such as the chaotic-chaotic patterns, periodic-chaotic patterns, chaotic line soliton patterns, chaotic dromion patterns, fractal lump patterns, and fractal dromion patterns may be found in higher dimensional soliton systems. The interactions between the traveling ring type soliton solutions are completely elastic. The traveling ring solitons pass through each other and preserve their shapes, velocities, and phases. Some types of localized weak solutions, peakons, are also discussed. Especially, the interactions between two peakons are not completely elastic. After the interactions, the traveling peakons also pass through each other and preserve their velocities and phases, however, they completely exchange their shapes. PMID:12443343

Tang, Xiao-Yan; Lou, Sen-Yue; Zhang, Ying

2002-10-01

82

How Nonlinear Interactions Challenge the Three-Dimensional Anderson Transition  

NASA Astrophysics Data System (ADS)

In disordered systems, our present understanding of the Anderson transition is hampered by the possible presence of interactions between particles. We demonstrate that in boson gases, even weak interactions deeply alter the very nature of the Anderson transition. While there still exists a critical point in the system, below that point a novel phase appears, displaying a new critical exponent, subdiffusive transport, and a breakdown of the one-parameter scaling description of Anderson localization.

Cherroret, Nicolas; Vermersch, Benoît.; Garreau, Jean Claude; Delande, Dominique

2014-05-01

83

How nonlinear interactions challenge the three-dimensional anderson transition.  

PubMed

In disordered systems, our present understanding of the Anderson transition is hampered by the possible presence of interactions between particles. We demonstrate that in boson gases, even weak interactions deeply alter the very nature of the Anderson transition. While there still exists a critical point in the system, below that point a novel phase appears, displaying a new critical exponent, subdiffusive transport, and a breakdown of the one-parameter scaling description of Anderson localization. PMID:24836228

Cherroret, Nicolas; Vermersch, Benoît; Garreau, Jean Claude; Delande, Dominique

2014-05-01

84

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

85

Dynamics of solvent-mediated electron localization in electronically excited hexacyanoferrate(III).  

PubMed

We have used polarization-resolved UV pump-mid-IR probe spectroscopy to investigate the dynamics of electron hole localization for excited-state ligand-to-metal charge-transfer (LMCT) excitation in Fe(CN)(6)(3-). The initially generated LMCT excited state has a single CN-stretch absorption band with no anisotropy. This provides strong evidence that this initial excited state preserves the octahedral symmetry of the electronic ground state by delocalizing the ligand hole in the LMCT excited state on all six cyanide ligands. This delocalized LMCT excited state decays to a second excited state with two CN-stretch absorption bands. We attribute both peaks to a single excited state because the formation time for both peaks matches the decay time for the delocalized LMCT excited state. The presence of two CN-stretch absorption bands demonstrates that this secondary excited state has lower symmetry. This observation, in conjunction with the solvent-dependent time constant for the formation of the secondary excited state, leads us to conclude that the secondary excited state corresponds to a LMCT state with a localized ligand hole. PMID:22233125

Zhang, Wenkai; Ji, Minbiao; Sun, Zheng; Gaffney, Kelly J

2012-02-01

86

Excitation by Local Electric Fields in the Aurora and Airglow  

Microsoft Academic Search

We have developed a method for accurate calculation of the distribution of electron energies in the ionosphere under the influence of an electric field. From this calculation we can predict rates of excitation of radiating states of N., O., and O as a function of the strength of a hypothetical applied field. We find that it is unreasonable to expect

L. R. Megill; N. P. Carleton

1964-01-01

87

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

88

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

89

State-selective optimization of local excited electronic states in extended systems  

NASA Astrophysics Data System (ADS)

Standard implementations of time-dependent density-functional theory (TDDFT) for the calculation of excitation energies give access to a number of the lowest-lying electronic excitations of a molecule under study. For extended systems, this can become cumbersome if a particular excited state is sought-after because many electronic transitions may be present. This often means that even for systems of moderate size, a multitude of excited states needs to be calculated to cover a certain energy range. Here, we present an algorithm for the selective determination of predefined excited electronic states in an extended system. A guess transition density in terms of orbital transitions has to be provided for the excitation that shall be optimized. The approach employs root-homing techniques together with iterative subspace diagonalization methods to optimize the electronic transition. We illustrate the advantages of this method for solvated molecules, core-excitations of metal complexes, and adsorbates at cluster surfaces. In particular, we study the local ?-->?* excitation of a pyridine molecule adsorbed at a silver cluster. It is shown that the method works very efficiently even for high-lying excited states. We demonstrate that the assumption of a single, well-defined local excitation is, in general, not justified for extended systems, which can lead to root-switching during optimization. In those cases, the method can give important information about the spectral distribution of the orbital transition employed as a guess.

Kovyrshin, Arseny; Neugebauer, Johannes

2010-11-01

90

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

91

Excitonic Bound State in the Extended Anderson Model with c-f Coulomb Interaction  

NASA Astrophysics Data System (ADS)

The Anderson model with the Coulomb interaction between the local and conduction electrons is studied in the semiconducting phase. Based on a perturbation theory from the atomic limit, leading contributions for the c-f Coulomb interaction are incorporated as a vertex correction to hybridization. An analytical solution shows that the effective attraction in the intermediate states leads to a bound state localized at the local electron site. Self-consistent equations are constructed as an extension of the non-crossing approximation (NCA) to include the vertex part yielding the bound state. A numerical calculation demonstrates the excitonic bound state inside the semiconducting gap for single-particle excitations, and a discontinuity at the gap edge for magnetic excitations.

Otsuki, Junya

2007-06-01

92

Localized wake-field excitation and relativistic wave-breaking  

SciTech Connect

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

Lehmann, G.; Laedke, E. W.; Spatschek, K. H. [Institut fuer Theoretische Physik, Heinrich-Heine-Universitaet Duesseldorf, D-40225 Duesseldorf (Germany)

2007-10-15

93

Action localization and resonance of highly excited vibrational triatomic system  

Microsoft Academic Search

An algebraic Hamiltonian for H2O, D2O, H2S, CH2 of CH2Br2 and CD2 of CD2Br2 containing anharmonicities and resonances is proposed with coefficients elucidated from the fit with the experimentally observed levels. It is demonstrated that most often the anharmonic parts show clues of action (energy) localization. Resonances are shown full of periodic, quasiperiodic and chaotic motion, while the intersection of

Zhongqing Ji; Guozhen Wu

2000-01-01

94

Entanglement entropy of low-lying excitation in localized interacting system: Signature of Fock space delocalization  

NASA Astrophysics Data System (ADS)

The properties of the entanglement entropy (EE) of low-lying excitations in one-dimensional disordered interacting systems are studied. The ground state EE shows a clear signature of localization, while low-lying excitations show a significantly longer localization length. The dependence of the localization as a function of interaction strength and sample length is studied using the density matrix renormalization group (DMRG). This behavior corresponds to the presence of the predicted many-particle critical energy in the vicinity of the ground state energy. The implications of these results on experiments are discussed.

Berkovits, Richard

2014-05-01

95

Resonance localization in tokamaks excited with ICRF waves  

SciTech Connect

Advanced wave models used to evaluate ICRH in tokamaks typically use warm plasma theory and allow inhomogeneity in one dimension. The majority of these calculations neglect the fact that gyrocenters experience the inhomogeneity via their motion parallel to the magnetic field. The non-local effects of rotational transform and toroidicity can play a significant role in both the propagation and the absorption physics. In strongly driven systems, wave damping can distort the particle distribution function supporting the wave and this produces changes in the absorption. The most common approach is to use Maxwellian absorption rates. We have developed a bounce-averaged Fokker-Planck quasilinear computational model which evolves the population of particles on more realistic orbits. Each wave-particle resonance has its own specific interaction amplitude within any given volume element; these data need only be generated once, and appropriately stored for efficient retrieval. The wave-particle resonant interaction then serves as a mechanism by which the diffusion of particle populations can proceed among neighboring orbits. The local specific spectral energy absorption rate is directly calculable once the orbit geometry and populations are determined. The code is constructed in such fashion as to accommodate wave propagation models which provide the wave spectral energy density on a poloidal cross-section. Information provided by the calculation includes the local absorption properties of the medium which can then be exploited to evolve the wave field.

Kerbel, G.D.; McCoy, M.G.

1985-06-20

96

Local bifurcations of synchronization in self-excited and forced unidirectionally coupled micromechanical resonators  

NASA Astrophysics Data System (ADS)

A unidirectionally coupled system of Microelectromechanical Systems (MEMS) resonators is investigated. Local bifurcations of both the single resonator and the coupled system are analyzed in the design of the coupled system. We discuss the behavior of the coupled system according to the change in the coupling parameter and the excitation force. Phenomena such as quasiperiodic oscillations and synchronization are shown by numerical simulations and studied analytically through perturbation methods. The coupled system shows oscillatory behavior without the excitation force. In the presence of the excitation force the coupled system exhibits complex behavior which can be beneficial in the design of the coupled system as a sensor.

Naik, Suketu; Hikihara, Takashi; Vu, Huy; Palacios, Antonio; In, Visarath; Longhini, Patrick

2012-02-01

97

America's First Illustrator: Alexander Anderson  

NSDL National Science Digital Library

The New York Public Library presents this digital edition of the scrapbooks of 19th-century master illustrator Alexander Anderson. During his 70-year career, Anderson (1775-1870) created wood engravings to illustrate books, periodicals, newspapers, broadsides, and posters, based on his own designs, and the work of other artists. Some of the more prominent works illustrated by Anderson include John Bunyan's "Pilgrim's Progress", O.L. Holley's "Life of Benjamin Franklin", surveys of architecture, and books intended for teaching school children. This digital collection contains 1,332 of Anderson's engravings that can be browsed or searched by subject. To help interested users determine where images in the scrapbooks may have been published, titles of several major printed catalogs of Anderson's work are listed on the collection guide.

98

Effect of structural distortion and polarization in localization of electronic excitations in organic semiconductor materials  

NASA Astrophysics Data System (ADS)

Organic polymers find varied applications in optoelectronic devices such as solar cells, light emitting diodes and lasers. Detailed understanding of charge carrier transport by polarons and excitonic energy transfer producing singlet and triplet excitations is critical to improve their efficiency. We benchmarked the ability of current functional models to describe the spatial extent of self-trapped neutral and charged excitations for MEH-PPV owing to its superior luminescence and experimental evidence. Now we are interested in distinguishing between two distinct origins leading to localization; spatial localization of the wavefunction by itself on the undistorted geometry and localization of the wavefunction assured by distortion of the structure during its relaxation. We suggest localization is produced by electronic rearrangements and character of the functional. We also observe that different functionals place the highest occupied and lowest virtual orbitals at different positions in the energy band diagram based on their ability to predict the extent of localization of these states.

Nayyar, Iffat; Batista, Enrique; Tretiak, Sergei; Saxena, Avadh; Smith, Darryl; Martin, Richard

2012-02-01

99

Localized excitations in amorphous silicon alloys. Final report  

SciTech Connect

The valence band edge of a-Si:H is sensitive to H content, while the conduction band edge is not. The optical gap increases 50% going from the isolated SiH group to the polysilane configuration; the smallest energy gap was for the polycrystal models for a-Si:H. Only the complexes involving the Si dangling bond give rise to active states deep in he a-Si fundamental energy gap. Positions of dangling bond defect state agree with photoluminescence of undoped and oxidized a-Si:H films. Incorporation of halogens into a-Si:H increases the optical gap, quasi-localized states near conduction band tail, and resonances deep in the valence band. Carbon increases the optical gap and produces resonances deep in both bands, while tin does not increase the optical gap and produces resonances in upper part of a-Si:H valence band; this is consistent with a model based on relative strength of Si-Si bond to Si-impurity bond. Effects of P dopant are consistent with models based on P in a-Si:H producing dopant-defect pairs, increased Fermi energy, etc. B substitutional dopants (tetrahedral) produces states near the valence band edge which resemble the show impurity levels in crystalline Si. Trigonally bonded B gives rise to states within the a-Si:H fundamental gap. B-H complexes suggest B-H bonds in B-doped a-Si:H, even at low B contents. Figs, 22 refs. (DLC)

Not Available

1987-10-01

100

Anderson's Orthogonality Catastrophe  

NASA Astrophysics Data System (ADS)

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

Gebert, Martin; Küttler, Heinrich; Müller, Peter

2014-03-01

101

Accurate singlet and triplet excitation energies using the Localized Hartree–Fock Kohn–Sham potential  

Microsoft Academic Search

We assess the accuracy of the LHFX Time-Dependent Density-Functional Theory (TD-DFT) approach, which uses Kohn–Sham orbitals and eigenvalues from the Localized Hartree–Fock (LHF) method and the exchange-only adiabatic local density approximation kernel. We compute 172 singlet and triplet excitation energies of ????, n???, ???? and Rydberg character, for organic molecules of different size. We find that the LHFX method, which

F. Della Sala; E. Fabiano

102

Excitation energies through the locally renormalized equation-of-motion formalism: Singles and doubles model  

NASA Astrophysics Data System (ADS)

The stationary conditions obtained from approximate coupled-cluster functional derived from the numerator-denominator connected expansion (NDC) [K. Kowalski and P. Piecuch, J. Chem. Phys. 122, 074107 (2005)] are employed to calculate the linear response of cluster amplitudes. A simple scheme that involves singly and doubly excited amplitudes, termed locally renormalized equation-of-motion approach with singles and doubles (LR-EOMCCSD), is compared with other excited-state methods that include up to two-body operators in the wave function expansion. In particular, the impact of the local denominators on the excitation energies is discussed in detail. Several benchmark calculations on the CH+, C2, N2, O3, and ClOCl molecules are presented to illustrate the performance of the LR-EOMCCSD approach.

Kowalski, Karol

2006-09-01

103

Intrinsic localized states and nonlinear excitations of Bloch electrons in electric fields  

Microsoft Academic Search

This paper addresses the dynamics of Bloch electrons with Coulomb interaction on a discrete lattice in the electric fields. The analysis is based on exact calculations with the inverse scattering method. The results are interesting, and include intrinsic localized states and nonlinear excitations of Bloch electrons. Such a system can be written as an extended Hubbard model,1 which is relevant

W. M. Liu; J. Q. Liang; S. T. Chui

2001-01-01

104

Covalent bonding effect on the mean excitation energy of H2 with the local plasma model  

NASA Technical Reports Server (NTRS)

Chemical bonding is taken into account explicitly in the determination of the mean excitation energy (I) for stopping power of H2 with the local plasma approximation by employing molecular electronic wave functions for H2 for the first time. This procedure leads to a new value for IH2 that is higher than all accepted experimental and theoretical values.

Kamaratos, E.

1984-01-01

105

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

106

Potential-energy surfaces of local excited states from subsystem- and selective Kohn-Sham-TDDFT  

NASA Astrophysics Data System (ADS)

Calculating excited-state potential-energy surfaces for systems with a large number of close-lying excited states requires the identification of the relevant electronic transitions for several geometric structures. Time-dependent density functional theory (TDDFT) is very efficient in such calculations, but the assignment of local excited states of the active molecule can be difficult. We compare the results of the frozen-density embedding (FDE) method with those of standard Kohn-Sham density-functional theory (KS-DFT) and simpler QM/MM-type methods. The FDE results are found to be more accurate for the geometry dependence of excitation energies than classical models. We also discuss how selective iterative diagonalization schemes can be exploited to directly target specific excitations for different structures. Problems due to strongly interacting orbital transitions and possible solutions are discussed. Finally, we apply FDE and the selective KS-TDDFT to investigate the potential energy surface of a high-lying ? ? ?? excitation in a pyridine molecule approaching a silver cluster.

Kovyrshin, Arseny; Neugebauer, Johannes

2011-11-01

107

Accurate singlet and triplet excitation energies using the Localized Hartree-Fock Kohn-Sham potential  

NASA Astrophysics Data System (ADS)

We assess the accuracy of the LHFX Time-Dependent Density-Functional Theory (TD-DFT) approach, which uses Kohn-Sham orbitals and eigenvalues from the Localized Hartree-Fock (LHF) method and the exchange-only adiabatic local density approximation kernel. We compute 172 singlet and triplet excitation energies of ? ? ??, n ? ??, ? ? ?? and Rydberg character, for organic molecules of different size. We find that the LHFX method, which is free from the Self-Interaction-Error (SIE) and from empirical parameters, outperforms the state-of-the-art hybrid TD-DFT approaches, and provides the same accuracy for all different classes of excitations. The SIE-free Kohn-Sham orbitals can be thus considered as starting point for TD-DFT developments.

Della Sala, F.; Fabiano, E.

2011-11-01

108

Evolutional Properties of Localized Excitations for Generalized Broer-Kaup System in (2+1) Dimensions  

NASA Astrophysics Data System (ADS)

Using a special Painlevé-Bäcklund transformation as well as the extended mapping approach and the linear superposition theorem, we obtain new families of variable separation solutions to the (2+1)-dimensional generalized Broer-Kaup (GBK) system. Based on the derived exact solution, we reveal some novel evolutional behaviors of localized excitations, i.e. fission and fusion phenomena in the (2+1)-dimensional GBK system.

Zheng, Chun-Long; Ye, Jian-Feng; Xu, Yuan

2006-09-01

109

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

PubMed

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

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

2004-06-25

110

Method for the three-dimensional localization of intramyocardial excitation centers using optical imaging.  

PubMed

This study explores the possibility of localizing the excitation centers of electrical waves inside the heart wall using voltage-sensitive dyes (fluorescent or absorptive). In the present study, we propose a method for the 3-D localization of excitation centers from pairs of 2-D images obtained in two modes of observation: reflection and transillumination. Such images can be obtained using high-speed charge-coupled device (CCD) cameras and photodiode arrays with time resolution up to 0.5 ms. To test the method, we simulate optical signals produced by point sources and propagating ellipsoidal waves in 1-cm-thick slabs of myocardial tissue. Solutions of the optical diffusion equation are constructed by employing the method of images with Robin boundary conditions. The coordinates of point sources as well as of the centers of expanding waves can be accurately determined using the proposed algorithm. The method can be extended to depth estimations of the outer boundaries of the expanding wave. The depth estimates are based on ratios of spatially integrated images. The method shows high tolerance to noise and can give accurate results even at relatively low signal-to-noise ratios. In conclusion, we propose a novel and efficient algorithm for the localization of excitation centers in 3-D cardiac tissue. PMID:16822057

Khait, Vadim D; Bernus, Olivier; Mironov, Sergey F; Pertsov, Arkady M

2006-01-01

111

Local heating of ZnO due to the surface plasmon excitation of Au nanoparticles  

NASA Astrophysics Data System (ADS)

Temperature dependent E2(high) Raman active optical phonon mode was investigated to identify the local heating of the ZnO, due to the surface plasmon excitation of the Au nanoparticles. The variation of the linewidth (FWHM) of E2(high) mode for ZnO was investigated from room temperature to 450 ^oC with 25 ^oC steps under constant 532 nm laser excitation intensity of 2.6*10^5 W/m^2. Linewidth (FWHM) was increased with the temperature and it was fitted into the theoretical model originally developed by Menendez et al, which contains both cubic and quadratic anharmonicities. After optimizing the cubic and quadratic anharmonic coupling constants, the fit was used to estimate the local temperatures of Au/ZnO, which were irradiated with different laser intensities. The estimated local temperature for Au/ZnO was 613 ^oC at the laser intensity of 8.1*10^5 W/m^2. ZnO without Au nanoparticles didn't show any large temperature variation under the different laser intensities. This is a clear evidence for the heat generation of Au nanoparticles due to the surface plasmon excitation.

Ranasingha, Oshadha; Wang, Congjun; Lewis, James P.; Matranga, Christopher

2013-03-01

112

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

113

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

NASA Technical Reports Server (NTRS)

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

Brown, Clifford A.

2011-01-01

114

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

PubMed

We study the nonlinear optical properties of lithium niobate (LiNbO(3)) 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 LiNbO(3) NWs of typical rectangular cross-sections of 400 x 600 nm(2) 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 nm(2)) 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

115

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

116

The time-dependent local density approximation for collective excitations of atomic clusters  

NASA Astrophysics Data System (ADS)

We discuss the calculation of collective excitations in atomic clusters using the time-dependent local density approximation. In principle there are many formulations of the TDLDA, but we have found that a particularly efficient method for large clusters is to use a coordinate space mesh and the algorithms for the operators and the evolution equations that had been developed for the nuclear time-dependent Hartree-Fock theory. The TDLDA works remarkably well to describe the strong excitations in alkali metal clusters and in carbon clusters. We show as an example the benzene molecule, which has two strong features in its spectrum. The systematics of the linear carbon chains is well reproduced, and may be understood in rather simple terms.

Bertsch, G. F.; Yabana, K.

1997-06-01

117

M D Anderson Cancer Center  

Cancer.gov

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

118

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

119

Coupling between localized resonance and excitation of surface waves in metal hole arrays  

NASA Astrophysics Data System (ADS)

We investigate the transition of the dominant resonant transmission mechanism from localized resonance to excitation of surface waves and vice versa in metal hole arrays. The transition occurs continuously with a change in the length of the rectangular holes. We also study the effect of the incident-beam diameter and surface condition on the transmission spectrum. Our experimental results show the important differences between the two mechanisms. They also confirm the theoretical prediction of Bravo-Abad [Phys. Rev. B 76, 241102(R) (2007)].

Miyamaru, Fumiaki; Takeda, Mitsuo Wada

2009-04-01

120

Localized fluorescence excitation in opaque media by time-reversed ultrasonically encoded (TRUE) optical focusing  

NASA Astrophysics Data System (ADS)

To focus light beyond one transport mean free path, time-reversed ultrasonically encoded (TRUE) optical focusing has previously been implemented by both analog and digital devices. By allowing wavefront recording with finer resolution and larger aperture, the analog scheme, which uses photorefractive materials as the phase-conjugate mirror, generates a more complete set of time-reversed optical modes than the digital scheme. Here, we report the direct visualization of localized fluorescence excitation inside a turbid medium by photorefractive time reversal. Further, we imaged fluorescent targets embedded in a turbid phantom whose thickness was four transport mean free paths.

Suzuki, Yuta; Lai, Puxiang; Xu, Xiao; Wang, Lihong

2014-03-01

121

Localized excited charge carriers generate ultrafast inhomogeneous strain in the multiferroic BiFeO3.  

PubMed

We apply ultrafast x-ray diffraction with femtosecond temporal resolution to monitor the lattice dynamics in a thin film of multiferroic BiFeO3 after above-band-gap photoexcitation. The sound-velocity limited evolution of the observed lattice strains indicates a quasi-instantaneous photoinduced stress which decays on a nanosecond time scale. This stress exhibits an inhomogeneous spatial profile evidenced by the broadening of the Bragg peak. These new data require substantial modification of existing models of photogenerated stresses in BiFeO3: the relevant excited charge carriers must remain localized to be consistent with the data. PMID:24655276

Schick, Daniel; Herzog, Marc; Wen, Haidan; Chen, Pice; Adamo, Carolina; Gaal, Peter; Schlom, Darrell G; Evans, Paul G; Li, Yuelin; Bargheer, Matias

2014-03-01

122

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

123

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

2013-10-11

124

Legendre transformation in hubbard and anderson models  

NASA Astrophysics Data System (ADS)

The previously derived variational-derivative equations for the Hubbard model and for the single-impurity Anderson model after the Legendre transformation are represented in the form of a set of two nonlinear integral equations. The one-particle propagators of the number of particles and of the momentum that are defined by these equations exhibit a regular behavior in three limiting cases. First, for both models in the limit of the zero width of the conduction band ( W/ U = 0) there is obtained a result known as the atomic limit. Second, it has been shown that in the limit of U/ W ? 1 the Pauli principle in the form of an additional coupling equation excludes from the perturbation-theory series some class of diagrams that are present in the standard expansion. Finally, for the case of U = ? and N e = N at - 1 in the framework of the Hubbard model there has been obtained an equation that agrees with the exact Nagaoka statement on the saturated ferromagnetism. A calculation has been performed of the density of impurity electron states in the symmetrical Anderson model in the paramagnetic phase for various values of the parameters of the Coulomb interaction U/?? and temperature T/?, where ? is the width of the localized impurity level. The calculation results are in good agreement with the results obtained by other methods.

Chashchin, N. I.

2011-04-01

125

General variable separation solution and new localized excitations for the (2+1)-dimensional nonlinear Schrodinger equation  

NASA Astrophysics Data System (ADS)

By applying a special Backlund transformation, a general variable separation Solution for the (2 + 1)-dimensional nonlinear Schrodinger equation is derived. In addition to some types of the usual localized excitations, Such as dromions, lumps, ring solitons, oscillated dromions, and breathers, soliton structures can be easily constructed by selecting arbitrary functions appropriately. A new class of localized excitations, like fractal-dromions, fractal-lumps, peakons, compactors, and folded excitations of this system is found by selecting appropriate functions. Some interesting novel features of these structures are revealed.

Bai, Cheng-Lin; Hu, Hai-Quan; Wang, Wen-Jun; Zhao, Hong

2006-12-01

126

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

NASA Technical Reports Server (NTRS)

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

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

1984-01-01

127

Localization of bleomycin in a single living cell using three-photon excitation microscopy  

NASA Astrophysics Data System (ADS)

Bleomycin has been used in the clinic as a chemotherapeutic agent for the treatment of several neoplasms, including non-Hodgkins lymphomas, squamous cell carcinomas, and testicular tumors. The effectiveness of bleomycin is believed to be derived from its ability to bind and oxidatively cleave DNA in the presence of a iron cofactor in vivo. A substantial amount of data on BLM has been collected, there is little information concerning the effects of bleomycin in living cells. In order to obtain data pertinent to the effects of BLM in intact cells, we have exploited the intrinsic fluorescence property of bleomycin to monitor the uptake of the drug in mammalian cells. We employed two light microscopy techniques, a wide-field and three-photon excitation (760 nm) fluorescence microscopy. Treatment of HeLa cells with bleomycin resulted in rapid to localization within the cells. In addition data collected from the wide field experiments, three-photon excitation of BLM which considerably reduced the phototoxic effect compared with UV light excitation in the wide-field microscopy indicated co-localization of the drug to regions of the cytoplasm occupied by the endoplasmic reticulum probe, DiOC5. The data clearly indicates that the cellular uptake of bleomycin after one minute includes the nucleus as well as in cytoplasm. Contrary to previous studies, which indicate chromosomal DNA as the target of bleomycin, the current findings suggest that the drug is distributed to many areas within the cell, including the endoplasmic reticulum, an organelle that is known to contain ribonucleic acids.

Abraham, Anil T.; Brautigan, David L.; Hecht, Sidney M.; Periasamy, Ammasi

2001-04-01

128

America's First Illustrator: Alexander Anderson  

NSDL National Science Digital Library

America has produced many notable wood engravers, but Alexander Anderson is one of the first to have name recognition. Born in 1775, he spent his lifetime crafting illustrations for books, periodicals, newspapers, and other commercial ephemera. This delightful digital collection from the New York Public Library brings together sixteen scrapbooks containing almost 10,000 wood engravings by Anderson. Visitors can click on the "Browse Source Titles" area to view the various volumes, and the subjects covered here are quite diverse. Even a cursory search returns dozens of cat engravings, illustrations of slaves, and lottery advertisements. For anyone with an interest in 19th century material culture, this collection is truly wonderful. It is worth making several return trips to get a full sense of the offerings here, and it is one that will bring new rewards upon each visit.

129

Application of the Coupled-Cluster Method to the Single-Impurity Anderson Model  

NASA Astrophysics Data System (ADS)

The Coupled-Cluster method (CCM) is applied to the well known single-impurity Anderson model wherein hybridization may occur between a localized f-orbital and a filled Fermi-sea of conduction electrons. The basic ansatz of the CCM is to write the true wave function ? in terms of a ground-state function ?0 as |?>=e^tildeS|?_0> where the operators tildeS describe the excitations of the system. For this particular system we choose |?_0>=f^_?|0>_f|F> where |F> denotes a filled sea of conduction electrons while |0>f is the unoccupied f-orbital. A simple expression for the ground-state energy is derived and comparisons are made with other methods.

Barry, E.; Farley, C.; Sheridan, K.; Mancini, J.; Fessatidis, V.; Bowen, S.

2003-03-01

130

Ground-state properties of the periodic Anderson model  

NASA Technical Reports Server (NTRS)

The ground-state energy, hybridization matrix element, local moment, and spin-density correlations of a one-dimensional, finite-chain, periodic, symmetric Anderson model are obtained by numerical simulations and compared with perturbation theory and strong-coupling results. It is found that the local f-electron spins are compensated by correlation with other f-electrons as well as band electrons leading to a nonmagnetic ground state.

Blankenbecler, R.; Fulco, J. R.; Gill, W.; Scalapino, D. J.

1987-01-01

131

Anderson testifies on Planet Earth  

NASA Astrophysics Data System (ADS)

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

Wainger, Lisa A.

132

How local excitation-inhibition ratio impacts the whole brain dynamics.  

PubMed

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

Deco, Gustavo; Ponce-Alvarez, Adrián; Hagmann, Patric; Romani, Gian Luca; Mantini, Dante; Corbetta, Maurizio

2014-06-01

133

Dispersion energy evaluated by using locally projected occupied and excited molecular orbitals for molecular interaction  

NASA Astrophysics Data System (ADS)

The dispersion terms are evaluated with the perturbation theory based on the locally projected molecular orbitals. A series of model systems, including some of the S22 set, is examined, and the calculated binding energies are compared with the published results. The basis set dependence is also examined. The dispersion energy correction is evaluated by taking into account the double excitations only of the dispersion type electron configurations and is added to the 3rd order single excitation perturbation energy, which is a good approximation to the counterpoise (CP) corrected Hartree-Fock (HF) binding energy. The procedure is the approximate ``CP corrected HF + D'' method. It ensures that the evaluated binding energy is approximately free of the basis set superposition error without the CP procedure. If the augmented basis functions are used, the evaluated binding energies for the predominantly dispersion-bound systems, such as rare gas dimers and halogen bonded clusters, agree with those of the reference calculations within 1 kcal mol-1 (4 kJ mol-1). The limitation of the present method is also discussed.

Iwata, Suehiro

2011-09-01

134

Fluorescence imaging of local membrane electric fields during the excitation of single neurons in culture.  

PubMed Central

The spatial distribution of depolarized patches of membrane during the excitation of single neurons in culture has been recorded with a high spatial resolution (1 micron2/pixel) imaging system based on a liquid-nitrogen-cooled astronomical camera mounted on an inverted microscope. Images were captured from rat nodose neurons stained with the voltage-sensitive dye RH237. Conventional intracellular microelectrode recordings were made in synchrony with the images. During an action potential the fluorescence changes occurred in localized, unevenly distributed membrane areas, which formed clusters of depolarized sites of different sizes and intensities. When fast conductances were blocked by the addition of tetrodotoxin, a reduction in the number and the intensities of the depolarized sites was observed. The blockade by tetrodotoxin of voltage-clamped neurons also reduced the number of depolarized sites, although the same depolarizing voltage step was applied. Similarly, when a voltage-clamped neuron was depolarized by a constant-amplitude voltage step, the number of depolarized sites varied according to the degree of activation of the voltage-sensitive channels, which was modified by changing the holding potential. These results suggest that the spatial patterns of depolarization observed during excitation are related to the operations of ionic channels in the membrane. Images FIGURE 1 FIGURE 2 FIGURE 4 FIGURE 5 FIGURE 6 FIGURE 7

Gogan, P; Schmiedel-Jakob, I; Chitti, Y; Tyc-Dumont, S

1995-01-01

135

Localized excitations in discrete nonlinear Schrödinger systems: Effects of nonlocal dispersive interactions and noise  

NASA Astrophysics Data System (ADS)

A one-dimensional discrete nonlinear Schrödinger (DNLS) model with the power dependence, r- s on the distance r, of dispersive interactions is proposed. The stationary states of the system are studied both analytically and numerically. Two kinds of trial functions, exp-like and sech-like are exploited and the results of both approaches are compared. Both on-site and inter-site stationary states are investigated. It is shown that for s sufficiently large all features of the model are qualitatively the same as in the DNLS model with nearest-neighbor interaction. For s less than some critical value, scr, there is an interval of bistability where two stable stationary states exist at each excitation number. The bistability of on-site solitons may occur for dipole-dipole dispersive interaction ( s = 3), while scr for inter-site solitions is close to 2.1. In the framework of the DNLS equation with nearest-neighbor coupling we discuss the stability of highly localized, “breather-like”, excitations under the influence of thermal fluctuations. Numerical analysis shows that the lifetime of the breather is always finite and in a large parameter region inversely proportional to the noise variance for fixed damping and nonlinearity. We also find that the decay rate of the breather decreases with increasing nonlinearity and with increasing damping.

Rasmussen, K. Ø.; Christiansen, P. L.; Johansson, M.; Gaididei, Yu. B.; Mingaleev, S. F.

1998-03-01

136

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

137

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

138

Interpolation processes in object perception: reply to Anderson (2007).  

PubMed

P. J. Kellman, P. Garrigan, & T. F. Shipley presented a theory of 3-D interpolation in object perception. Along with results from many researchers, this work supports an emerging picture of how the visual system connects separate visible fragments to form objects. In his commentary, B. L. Anderson challenges parts of that view, especially the idea of a common underlying interpolation component in modal and amodal completion (the identity hypothesis). Here the authors analyze Anderson's evidence and argue that he neither provides any reason to abandon the identity hypothesis nor offers a viable alternative theory. The authors offer demonstrations and analyses indicating that interpolated contours can appear modally despite absence of the luminance relations, occlusion geometry, and surface attachment that Anderson claims to be necessary. The authors elaborate crossing interpolations as key cases in which modal and amodal appearance must be consequences of interpolation. Finally, the authors dispute Anderson's assertion that vision researchers are misguided in using objective performance methods, and they argue that his challenges to relatability fail because contour and surface processes, as well as local and global influences, have been distinguished experimentally. PMID:17500638

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

2007-04-01

139

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

140

Influence of interaction time and population redistribution on the localization of atomic excitation through electromagnetically induced transparency  

NASA Astrophysics Data System (ADS)

We study numerically the localization of atomic excitation based on the dark states formed through electromagnetically induced transparency using interfering coupling beams. In particular, we examine the formation of dark states in a system exhibiting hyperfine splitting, including the effects of optical pumping in this multilevel system, laser polarization, and finite interaction time, and explore the conditions that lead to optimal spatial resolution of the excitation. We find that optimal localization requires long interaction times, due to the slow approach of the atomic system to steady state near the nodes of the standing wave pattern.

Choi, J.; Elliott, D. S.

2014-01-01

141

Kubo-Anderson Mixing in the Turbulent Boundary Layer  

NASA Astrophysics Data System (ADS)

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

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

142

Energy Redistribution and Localization in the Excited States of Ruthenium(II) Polypyridyl Complexes,  

National Technical Information Service (NTIS)

Excited-state absorption and resonance Raman spectra of the mixed-ligand complexes Ru(bpy)(2+)(1) and Ru(bpy)2DIP(2+)(2)(DIP = 4,7-diphenylphenantroline) are reported. The excited-state spectra of these mixed-ligand complexes show that the excited-state e...

C. V. Kumar J. K. Barton I. R. Gould N. J. Turro J. Van Houten

1988-01-01

143

Phase Structure of the Topological Anderson Insulator  

NASA Astrophysics Data System (ADS)

We report the phase structure of disordered HgTe topological Anderson insulator in a 2-D geometry. We use exact diagonalization to calculate the spectrum and eigenstate structure, and recursive green's functions to calculate the conductance. All observables are measured at several system sizes, allowing us to determine phase transitions and two critical points. The quantized-conductance TAI phase contains two phases: TAI-I lying in a bulk band gap, and TAI-II where bulk states exist but are localized. We find that the TAI-II phase persists at disorder strengths where there is no bulk band gap; a bulk band gap is not necessary to obtain conductance quantization. In a previous work the weak-disorder edge of the TAI phase was explained as a transition into the bulk gap (TAI-I), but we find also a direct transition into the ungapped (TAI-II) quantized phase. Effective medium theory (SCBA) predicts well the boundaries and interior of the TAI-I phase, but fails at larger disorders including the interior of the TAI-II phase. When the system size is smaller than the bulk localization length, the quantized TAI region is bounded by either the bulk band edge or the localization length, but when the system size is large it is bounded by a transition of edge states.

Xu, Dongwei; Sacksteder, Vincent E.; Qi, Junjie; Liu, Jie; Jiang, Hua; Xie, X. C.

2012-02-01

144

Time-dependent localized Hartree-Fock density-functional linear response approach for photoionization of atomic excited states  

SciTech Connect

We present a time-dependent localized Hartree-Fock density-functional linear response approach for the treatment of photoionization of atomic systems. This approach employs a spin-dependent localized Hartree-Fock exchange potential to calculate electron orbitals and kernel functions, and thus can be used to study the photoionization from atomic excited states. We have applied the approach to the calculation of photoionization cross sections of Ne ground state. The results are in agreement with available experimental data and have comparable accuracies with other ab initio theoretical results. We have also extended the approach to explore the photoionization from Ne excited states and obtained some results for the photoionization from outer-shell and inner-shell excited states.

Zhou Zhongyuan; Chu, S.-I [Department of Chemistry, University of Kansas, Lawrence, Kansas 66045 (United States)

2009-05-15

145

Mapping the Local Organization of Cell Membranes Using Excitation-Polarization-Resolved Confocal Fluorescence Microscopy  

PubMed Central

Fluorescence anisotropy and linear dichroism imaging have been widely used for imaging biomolecular orientational distributions in protein aggregates, fibrillar structures of cells, and cell membranes. However, these techniques do not give access to complete orientational order information in a whole image, because their use is limited to parts of the sample where the average orientation of molecules is known a priori. Fluorescence anisotropy is also highly sensitive to depolarization mechanisms such as those induced by fluorescence energy transfer. A fully excitation-polarization-resolved fluorescence microscopy imaging that relies on the use of a tunable incident polarization and a nonpolarized detection is able to circumvent these limitations. We have developed such a technique in confocal epifluorescence microscopy, giving access to new regions of study in the complex and heterogeneous molecular organization of cell membranes. Using this technique, we demonstrate morphological changes at the subdiffraction scale in labeled COS-7 cell membranes whose cytoskeleton is perturbed. Molecular orientational order is also seen to be affected by cholesterol depletion, reflecting the strong interplay between lipid-packing regions and their nearby cytoskeleton. This noninvasive optical technique can reveal local organization in cell membranes when used as a complement to existing methods such as generalized polarization.

Kress, Alla; Wang, Xiao; Ranchon, Hubert; Savatier, Julien; Rigneault, Herve; Ferrand, Patrick; Brasselet, Sophie

2013-01-01

146

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

147

New superconducting state of the Anderson-lattice model  

NASA Astrophysics Data System (ADS)

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

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

1989-11-01

148

Einstein-Podolsky-Rosen Spatial Entanglement in Ordered and Anderson Photonic Lattices  

NASA Astrophysics Data System (ADS)

We demonstrate quantum walks of a photon pair in a spatially extended Einstein-Podolsky-Rosen state coupled into an on-chip multiport photonic lattice. By varying the degree of entanglement we observe Anderson localization for pairs in a separable state and Anderson colocalization for pairs in an Einstein-Podolsky-Rosen entangled state. In the former case, each photon localizes independently, while in the latter neither photon localizes, but the pair colocalizes—revealing unexpected survival of the spatial correlations through strong disorder.

Di Giuseppe, G.; Martin, L.; Perez-Leija, A.; Keil, R.; Dreisow, F.; Nolte, S.; Szameit, A.; Abouraddy, A. F.; Christodoulides, D. N.; Saleh, B. E. A.

2013-04-01

149

Subdivision Regulations, City of Anderson, South Carolina.  

National Technical Information Service (NTIS)

The regulations provide, in accordance with South Carolina law, for the regulation of the subdivision of land within the City of Anderson. Included therewith are procedures for preparing and approving plats; design standards for streets, alleys, or rights...

1968-01-01

150

Dr. Dianne Gates-Anderson (Spanish)  

NSDL National Science Digital Library

(Spanish version) Meg A. Mole interview different chemists to learn about their jobs. Dr. Dianne Gates-Anderson is an Environmental Process Engineer at the Department of Energy, Lawrence Livermore National Laboratory.

2012-01-01

151

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

152

Phase structure of the topological Anderson insulator  

NASA Astrophysics Data System (ADS)

We study the disordered topological Anderson insulator in a two-dimensional (square not strip) geometry. We first report the phase diagram of finite systems and then study the evolution of phase boundaries when the system size is increased to a very large 1120×1120 area. We establish that conductance quantization can occur without a bulk band gap, and that there are two distinct scaling regions with quantized conductance: TAI-I with a bulk band gap, and TAI-II with localized bulk states. We show that there is no intervening insulating phase between the bulk conduction phase and the TAI-I and TAI-II scaling regions, and that there is no metallic phase at the transition between the quantized and insulating phases. Centered near the quantized-insulating transition there are very broad peaks in the eigenstate size and fractal dimension d2; in a large portion of the conductance plateau eigenstates grow when the disorder strength is increased. The fractal dimension at the peak maximum is d2?1.5. Effective-medium theory (Coherent Potential Approximation, self-consistent Born approximation) predicts well the boundaries and interior of the gapped TAI-I scaling region, but fails to predict all boundaries save one of the ungapped TAI-II scaling region. We report conductance distributions near several phase transitions and compare them with critical conductance distributions for well-known models.

Xu, Dongwei; Qi, Junjie; Liu, Jie; Sacksteder, Vincent, IV; Xie, X. C.; Jiang, Hua

2012-05-01

153

Astronaut Anderson Works in SPACEHAB  

NASA Technical Reports Server (NTRS)

The Space Shuttle Orbiter Columbia STS-107 mission launched January 16, 2003. STS-107 is strictly a multidiscipline microgravity and Earth science research mission involving 80-plus International experiments to be performed during 16-days, many of which will be managed by the Marshall Space Flight Center in Huntsville, Alabama. The majority of the research will be conducted in the Shuttle's mid deck, the area directly under the cockpit, and in the new SPACEHAB Research Double Module. This is the first flight for that module, which doubles the volume available for experiments and significantly increases the amount and complexity of research from the last dedicated Shuttle science mission, STS-95, flown in 1998 with a single SPACEHAB module. The pressurized module is carried in Columbia's payload bay and is accessible to the crew via a turnel from the Shuttle's mid deck. Pictured is an interesting view, looking through the adjoining tunnel, of astronaut Michael P. Anderson, mission specialist, performing work in SPACEHAB. The first shuttle mission in 2003, the STS-107 mission marks the 113th flight overall in NASA's Space Shuttle program, and the 28th flight of the Space Shuttle Orbiter Columbia.

2003-01-01

154

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

SciTech Connect

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

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

2010-10-19

155

Inner-shell excitation of open-shell atoms: a spin-dependent localized Hartree Fock density-functional approach  

NASA Astrophysics Data System (ADS)

We present a spin-dependent localized Hartree-Fock (SLHF) density-functional approach for the treatment of inner-shell excited states of open-shell atomic systems. In this approach, the electron spin-orbitals and single-Slater-determinant energies of an electronic configuration are computed by solving the Kohn-Sham (KS) equation with SLHF exchange potential. The multiplet energy of an inner-shell excited state is evaluated from the single-Slater-determinant energies in terms of Slater's diagonal sum rule. Based on this procedure, we perform calculations of the total and excitation energies of inner-shell excited states of open-shell atomic systems: Li, B, Ne+, Ne2+, Ne3+ and Na. In the calculation, the electron correlation effect is taken into account via the correlation potential and energy functional of Perdew and Wang (PW) or of Lee, Yang and Parr (LYP). The calculated results are in good agreement with the available experimental and other ab initio theoretical data. In addition, new results for highly excited inner-shell states are also presented.

Zhou, Zhongyuan; Chu, Shih-I.

2007-11-01

156

A new type of localized fast moving electronic excitations in molecular chains  

NASA Astrophysics Data System (ADS)

It is shown that in a Holstein molecular chain placed in a strong longitudinal electric field some new types of excitations can arise. These excitations can transfer a charge over large distance (more than 1000 nucleotide pairs) along the chain retaining approximately their shapes. Excitations are formed only when a strong electric field either exists or quickly arises under especially preassigned conditions. These excitations transfer a charge even in the case when Holstein polarons are practically immobile. The results obtained are applied to synthetic homogeneous PolyG/PolyC DNA duplexes. They can also be provide the basis for explanation of famous H.W. Fink and C. Schönenberger experiment on long-range charge transfer in DNA.

Korshunova, A. N.; Lakhno, V. D.

2014-06-01

157

Local versus nonlocal description of the energy loss of electrons via plasmon excitation backscattering from solid surfaces  

NASA Astrophysics Data System (ADS)

The differences between the local and nonlocal descriptions of the energy loss of electrons backscattered from a Si surface, focusing on surface and bulk plasmon excitations, are studied quantitatively in the present work. Beyond the usually applied “V-shape” electron trajectories, calculations have done for realistic electron trajectories derived by Monte Carlo simulation even in the case of nonlocal description of the electron-energy-loss process. It allowed to perform the detailed investigation of the effects of the interference (i.e., the interaction of the electron with the electric field induced at the earlier stage of its trajectory) in case of real electron trajectories. It is clearly shown that significant interference effects occur only in the case of surface plasmon excitations, however, these are less pronounced than predicted by the simple V-shape trajectory approximation. Furthermore, it is pointed out that the error caused by neglecting interference effects in the case of the local description of electron energy losses through collective excitations in the near-surface region of the solid is less than 6.2% when the primary electron energy is higher than 500 eV. As a consequence, the application of Monte Carlo simulation techniques based on a local description of the electron-energy-loss process is possible at these primary electron energies in order to the fast modeling of the complete near-surface electron-transport process (including inelastic and elastic electron scattering) without significant errors due to the neglect of the interference effects.

Novák, M.

2009-07-01

158

Anderson transition in a three-dimensional kicked rotor  

NASA Astrophysics Data System (ADS)

We investigate Anderson localization in a three-dimensional (3D) kicked rotor. By a finite-size scaling analysis we identify a mobility edge for a certain value of the kicking strength k=kc . For k>kc dynamical localization does not occur, all eigenstates are delocalized and the spectral correlations are well described by Wigner-Dyson statistics. This can be understood by mapping the kicked rotor problem onto a 3D Anderson model (AM) where a band of metallic states exists for sufficiently weak disorder. Around the critical region k?kc we carry out a detailed study of the level statistics and quantum diffusion. In agreement with the predictions of the one parameter scaling theory (OPT) and with previous numerical simulations, the number variance is linear, level repulsion is still observed, and quantum diffusion is anomalous with ?p2??t2/3 . We note that in the 3D kicked rotor the dynamics is not random but deterministic. In order to estimate the differences between these two situations we have studied a 3D kicked rotor in which the kinetic term of the associated evolution matrix is random. A detailed numerical comparison shows that the differences between the two cases are relatively small. However in the deterministic case only a small set of irrational periods was used. A qualitative analysis of a much larger set suggests that deviations between the random and the deterministic kicked rotor can be important for certain choices of periods. Heuristically it is expected that localization effects will be weaker in a nonrandom potential since destructive interference will be less effective to arrest quantum diffusion. However we have found that certain choices of irrational periods enhance Anderson localization effects.

Wang, Jiao; García-García, Antonio M.

2009-03-01

159

Value of epicardial potential maps in localizing pre-excitation sites for radiofrequency ablation. A simulation study  

NASA Astrophysics Data System (ADS)

Using computer simulations, we systematically investigated the limitations of an inverse solution that employs the potential distribution on the epicardial surface as an equivalent source model in localizing pre-excitation sites in Wolff-Parkinson-White syndrome. A model of the human ventricular myocardium that features an anatomically accurate geometry, an intramural rotating anisotropy and a computational implementation of the excitation process based on electrotonic interactions among cells, was used to simulate body surface potential maps (BSPMs) for 35 pre-excitation sites positioned along the atrioventricular ring. Two individualized torso models were used to account for variations in torso boundaries. Epicardial potential maps (EPMs) were computed using the L-curve inverse solution. The measure for accuracy of the localization was the distance between a position of the minimum in the inverse EPMs and the actual site of pre-excitation in the ventricular model. When the volume conductor properties and lead positions of the torso were precisely known and the measurement noise was added to the simulated BSPMs, the minimum in the inverse EPMs was at 12 ms after the onset on average within cm of the pre-excitation site. When the standard torso model was used to localize the sites of onset of the pre-excitation sequence initiated in individualized male and female torso models, the mean distance between the minimum and the pre-excitation site was cm for the male torso and cm for the female torso. The findings of our study indicate that a location of the minimum in EPMs computed using the inverse solution can offer non-invasive means for pre-interventional planning of the ablative treatment.

Hren, Rok

1998-06-01

160

Optical properties of single plasmonic holes probed with local electron beam excitation.  

PubMed

Similar to nanoparticles, nanoscale holes form a basic building block in a wide array of nanophotonic devices. Here we study the spectral and angular cathodoluminescence response of individual nanoholes with diameters ranging from 50 to 180 nm. Taking advantage of the deep-subwavelength excitation resolution, we find that the holes can be excited efficiently at the edge of the hole and that the response becomes stronger in the near-infrared part of the spectrum for larger holes. Using finite-difference time-domain simulations, we characterize the resonant modes inside the holes. We measure the angle-resolved cathodoluminescence response and observe strong beaming toward the side of electron beam excitation, complementary to what was shown for nanoparticles. The angular response can be explained by assuming a coherent superposition of radiating dipole moments, where the contribution of in-plane magnetic and electric dipole components increases for larger diameters. PMID:24936945

Coenen, Toon; Polman, Albert

2014-07-22

161

Localization of excitations in silicon chains by electron donating side groups  

NASA Astrophysics Data System (ADS)

The fluorescence decay kinetics in the copolymer, poly(phenylmethyl-co-p- dimethylanilinemethyl silane) have been studied by steady state and time correlated fluorescence spectroscopy and three absorbing and emitting species are proposed to explain the complex fluorescence decay behavior. In the case of poly(phenyl methyl silane) homopolymer, excitations have been shown to delocalize over several tens of monomer units, however, in the copolymers discussed here the extent of the delocalization has been shown to be dependent on the degree of substitution of the dimethylaniline side group. In the more highly substituted copolymers the excitations are shown to be confined to almost a single monomer unit by the electron donating nature of the dimethylaniline side group. A simple geometric distribution of chain lengths is used to predict the delocalization length of the excitations.

Smith, David A.; Williams, Scott A.; Jenkner, P.; Miller, Robert D.; Ginsburg, E. J.; Hochstrasser, Robin M.

1994-01-01

162

Non-Fermi-liquid behavior in the periodic anderson model.  

PubMed

We study the Mott metal-insulator transition in the periodic Anderson model with dynamical mean field theory (DMFT). Near the quantum transition, we find a non-Fermi-liquid metallic state down to a vanishing temperature scale. We identify the origin of the non-Fermi-liquid behavior as being due to magnetic scattering of the doped carriers by the localized moments. The non-Fermi-liquid state can be tuned by either doping or external magnetic field. Our results show that the coupling to spatial magnetic fluctuations (absent in DMFT) is not a prerequisite to realizing a non-Fermi-liquid scenario for heavy fermion systems. PMID:18851550

Amaricci, A; Sordi, G; Rozenberg, M J

2008-10-01

163

Quantum Criticality of Quasi-One-Dimensional Topological Anderson Insulators  

NASA Astrophysics Data System (ADS)

We present an analytic theory of quantum criticality in the quasi-one-dimensional topological Anderson insulators of class AIII and BDI. We describe the systems in terms of two parameters (g, ?) representing localization and topological properties, respectively. Surfaces of half-integer valued ? define phase boundaries between distinct topological sectors. Upon increasing system size, the two parameters exhibit flow similar to the celebrated two-parameter flow describing the class A quantum Hall insulator. However, unlike the quantum Hall system, an exact analytical description of the entire phase diagram can be given. We check the quantitative validity of our theory by comparison to numerical transfer matrix computations.

Altland, Alexander; Bagrets, Dmitry; Fritz, Lars; Kamenev, Alex; Schmiedt, Hanno

2014-05-01

164

Size effects on transport properties in topological Anderson insulators  

NASA Astrophysics Data System (ADS)

We study the size effects on the transport properties in topological Anderson insulators (TAIs) by means of the Landauer-Büttiker formalism combined with the nonequilibrium Green function method. Conductances calculated for serval different widths of the nanoribbons reveal that there is no longer quantized plateaus for narrow nanoribbons. The local spin-resolved current distribution demonstrates that the edge states on the two sides can be coupled, leading to enhancement of backscattering as the width of the nanoribbon decreases, thus destroying the perfect quantization phenomena in the TAI. We also show that the main contribution to the nonquantized conductance also comes from edge states. Experiment proposals on TAI are discussed finally.

Li, Wei; Zang, Jiadong; Jiang, Yongjin

2011-07-01

165

High order perturbation theory for nonlinear Anderson model  

NASA Astrophysics Data System (ADS)

The perturbation expansion for the nonlinear Schrödinger equation with a random potential that was developed in earlier works by some of us is extended to higher orders. As the order is increased a solution that is valid for longer time can be found. In particular it is found that Anderson localization persists in the fifth and sixth orders for times when perturbation theory is valid. The perturbation expansion is asymptotic and for the value of the nonlinearity parameter used, the fifth order is the optimal order of the perturbation theory. There are indications that for the sixth order perturbation theory may not be valid.

Fleishon, Gal; Fishman, Shmuel; Soffer, Avy

2014-02-01

166

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

167

Local CC2 response method based on the Laplace transform: Analytic energy gradients for ground and excited states  

NASA Astrophysics Data System (ADS)

A multistate local CC2 response method for the calculation of analytic energy gradients with respect to nuclear displacements is presented for ground and electronically excited states. The gradient enables the search for equilibrium geometries of extended molecular systems. Laplace transform is used to partition the eigenvalue problem in order to obtain an effective singles eigenvalue problem and adaptive, state-specific local approximations. This leads to an approximation in the energy Lagrangian, which however is shown (by comparison with the corresponding gradient method without Laplace transform) to be of no concern for geometry optimizations. The accuracy of the local approximation is tested and the efficiency of the new code is demonstrated by application calculations devoted to a photocatalytic decarboxylation process of present interest.

Ledermüller, Katrin; Schütz, Martin

2014-04-01

168

Local CC2 response method based on the Laplace transform: Analytic energy gradients for ground and excited states.  

PubMed

A multistate local CC2 response method for the calculation of analytic energy gradients with respect to nuclear displacements is presented for ground and electronically excited states. The gradient enables the search for equilibrium geometries of extended molecular systems. Laplace transform is used to partition the eigenvalue problem in order to obtain an effective singles eigenvalue problem and adaptive, state-specific local approximations. This leads to an approximation in the energy Lagrangian, which however is shown (by comparison with the corresponding gradient method without Laplace transform) to be of no concern for geometry optimizations. The accuracy of the local approximation is tested and the efficiency of the new code is demonstrated by application calculations devoted to a photocatalytic decarboxylation process of present interest. PMID:24784259

Ledermüller, Katrin; Schütz, Martin

2014-04-28

169

Local negative magnetic permeability and possibility of observation of breather excitations in magnetic metamaterials  

NASA Astrophysics Data System (ADS)

It is shown that the long-wave dynamics and magnetic properties of one-dimensional systems constructed of the inductively and capacitively coupled split-ring resonators are described by the regularized nonlinear dispersive Klein-Gordon equations. It is found that in such systems a high-frequency magnetic field excites dynamic solitons on a "pedestal"—stable breathers, oscillating in anti-phase with respect to the background of uniform oscillations, which means the existence of regions with a negative magnetic permeability in the system. If supplemented by a medium with negative permittivity, such a system forms a "left-handed" metamaterial in which the regions with the breather excitations are transparent to electromagnetic radiation. This makes it possible to observe them experimentally.

Bogdan, M. M.; Charkina, O. V.

2014-03-01

170

Universality and the QCD Anderson transition.  

PubMed

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

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

2014-03-14

171

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

172

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

PubMed

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. PMID:23503010

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

173

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

174

The interplay between localized and propagating plasmonic excitations tracked in space and time.  

PubMed

In this work, the mutual coupling and coherent interaction of propagating and localized surface plasmons within a model-type plasmonic assembly is experimentally demonstrated, imaged, and analyzed. Using interferometric time-resolved photoemission electron microscopy the interplay between ultrashort surface plasmon polariton wave packets and plasmonic nanoantennas is monitored on subfemtosecond time scales. The data reveal real-time insights into dispersion and localization of electromagnetic fields as governed by the elementary modes determining the functionality of plasmonic operation units. PMID:24702430

Lemke, Christoph; Leissner, Till; Evlyukhin, Andrey; Radke, Jörn W; Klick, Alwin; Fiutowski, Jacek; Kjelstrup-Hansen, Jakob; Rubahn, Horst-Günter; Chichkov, Boris N; Reinhardt, Carsten; Bauer, Michael

2014-05-14

175

Hopping perturbation treatment of the periodic Anderson model around the atomic limit  

Microsoft Academic Search

The periodic Anderson model with two strongly correlated subsystems of d and f electrons and local on-site hybridization is investigated by considering the hopping of d electrons between lattice sites as perturbation. In zero order without the intersite transfer term, the system of correlated d and f electrons can be treated exactly. The delocalization of electrons and the corresponding renormalization

V. A. Moskalenko; P. Entel; M. Marinaro; N. B. Perkins; C. Holtfort

2001-01-01

176

The Possibility of Forming Coupled Pairs in the Periodic Anderson Model  

Microsoft Academic Search

We investigate the generalized periodic Anderson model describing two groups of strongly correlated (d- and f-) electrons with local hybridization of states and d-electron hopping between lattice sites from the standpoint of the possible appearance of coupled electron pairs in it. The atomic limit of this model admits an exact solution based on the canonical transformation method. The renormalized energy

D. F. Digor; P. Entel; M. Marinaro; V. A. Moskalenko; N. B. Perkins

2001-01-01

177

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.

178

Phase diagram of the anisotropic Anderson transition with the atomic kicked rotor: theory and experiment  

NASA Astrophysics Data System (ADS)

We realize experimentally a cold-atom system, the quasiperiodic kicked rotor, equivalent to the three-dimensional Anderson model of disordered solids where the anisotropy between the x direction and the y-z plane can be controlled by adjusting an experimentally accessible parameter. This allows us to study experimentally the disorder versus anisotropy phase diagram of the Anderson metal-insulator transition. Numerical and experimental data compare very well with each other and a theoretical analysis based on the self-consistent theory of localization correctly describes the observed behavior, illustrating the flexibility of cold-atom experiments for the study of transport phenomena in complex quantum systems.

Lopez, Matthias; Clément, Jean-François; Lemarié, Gabriel; Delande, Dominique; Szriftgiser, Pascal; Garreau, Jean Claude

2013-06-01

179

Extended multilinear variable separation approach and multivalued localized excitations for some (2+1)-dimensional integrable systems  

NASA Astrophysics Data System (ADS)

The multilinear variable separation approach and the related ``universal'' formula have been applied to many (2+1)-dimensional nonlinear systems. Starting from the universal formula, abundant (2+1)-dimensional localized excitations have been found. In this paper, the universal formula is extended in two different ways. One is obtained for the modified Nizhnik-Novikov-Veselov equation such that two universal terms can be combined linearly and this type of extension is also valid for the (2+1)-dimensional symmetric sine-Gordon system. The other is for the dispersive long wave equation, the Broer-Kaup-Kupershmidt system, the higher order Broer-Kaup-Kupershmidt system, and the Burgers system where arbitrary number of variable separated functions can be involved. Because of the existence of the arbitrary functions in both the original universal formula and its extended forms, the multivalued functions can be used to construct a new type of localized excitations, folded solitary waves (FSWs) and foldons. The FSWs and foldons may be ``folded'' in quite complicated ways and possess quite rich structures and multiplicate interaction properties.

Tang, Xiao-Yan; Lou, Sen-Yue

2003-09-01

180

The University of Texas MD Anderson Cancer Center  

Cancer.gov

The University of Texas MD Anderson Cancer Center (MD Anderson) was established by the Texas State Legislature in 1941. In 1971, after the passage of the National Cancer Act, MD Anderson became one of the nation’s first NCI-designated comprehensive cancer centers.

181

Algebraic and geometric mean density of states in topological Anderson insulators  

NASA Astrophysics Data System (ADS)

Algebraic and geometric mean density of states in disordered systems may reveal properties of electronic localization. In order to understand the topological phases with disorder in two dimensions, we present the calculated density of states for the disordered Bernevig-Hughes-Zhang model. The topological phase is characterized by a perfectly quantized conducting plateau, carried by helical edge states, in a two-terminal setup. In the presence of disorder, the bulk of the topological phase is either a band insulator or an Anderson insulator. Both of them can protect edge states from backscattering. The topological phases are explicitly distinguished as a topological band insulator or a topological Anderson insulator from the ratio of the algebraic mean density of states to the geometric mean density of states. The calculation reveals that the topological Anderson insulator can be induced by disorders from either a topologically trivial band insulator or a topologically nontrivial band insulator.

Zhang, Yan-Yang; Shen, Shun-Qing

2013-11-01

182

Locally renormalized coupled-cluster equations for singly and doubly excited clusters  

NASA Astrophysics Data System (ADS)

The Numerator-Denominator Connected (NDC) Expansion for the Coupled-Cluster (CC) method [K. Kowalski and P. Piecuch, J. Chem. Phys. 122, 074107 (2005)], is used to construct a new set of stationary conditions for approximate coupled-cluster approaches. Several CC approximations based on models involving singles and doubles (CCSD) are developed and discussed in the context of ground-state applications. The resulting locally-renormalized CCSD (LR-CCSD) equations are shown to regularize the expressions for the cluster amplitudes in the challenging situations that occur when the orbital energy differences approach zero. Affordable schemes for handling the local denominators (all-holes-Jn coupling), that naturally appear in locally renormalized formalisms, are also discussed.

Kowalski, Karol

2006-07-01

183

Near-unity broadband absorption designs for semiconducting nanowire arrays via localized radial mode excitation.  

PubMed

We report design methods for achieving near-unity broadband light absorption in sparse nanowire arrays, illustrated by results for visible absorption in GaAs nanowires on Si substrates. Sparse (<5% fill fraction) nanowire arrays achieve near unity absorption at wire resonant wavelengths due to coupling into 'leaky' radial waveguide modes of individual wires and wire-wire scattering processes. From a detailed conceptual development of radial mode resonant absorption, we demonstrate two specific geometric design approaches to achieve near unity broadband light absorption in sparse nanowire arrays: (i) introducing multiple wire radii within a small unit cell array to increase the number of resonant wavelengths, yielding a 15% absorption enhancement relative to a uniform nanowire array and (ii) tapering of nanowires to introduce a continuum of diameters and thus resonant wavelengths excited within a single wire, yielding an 18% absorption enhancement over a uniform nanowire array. PMID:24922398

Fountaine, Katherine T; Kendall, Christian G; Atwater, Harry A

2014-05-01

184

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

185

Localization of magnetic excitations in 1-D quasiperiodic chains: a semi-classical approach  

NASA Astrophysics Data System (ADS)

A semi-classical theory is employed to investigate the spin wave spectra and the localization profile of linear quasiperiodic binary superlattices, where one of their components is a ferromagnetic material, the other one being an antiferromagnet. The calculations are carried out for the exchange-dominated regime within the framework of the Heisenberg model, considering a torque equation of motion for the magnetizations. For numerical calculations, we consider the antiferromagnetic material as MnF 2, and Fe is the ferromagnetic one. The quasiperiodic arrangement gives rise to localized spin wave spectra, which were observed previously in analogous periodic structures, but only for higher dimensions. Such spectra is analyzed through evaluation of scaling exponents, explicitly demonstrating that our magnetic structure presents fractal features.

Fulco, U. L.; H. A. L. Anselmo, Dory; Albuquerque, E. L.

2004-11-01

186

Wave Localization on Complex Networks  

Microsoft Academic Search

\\u000a In this chapter we consider the role played by Anderson localization in transport through complex networks, for example, an\\u000a optical network. The network is described by a tight binding Hamiltonian, which may be used to determine the properties of\\u000a the Anderson transition according to the statistical properties of its eigenvalues. The Anderson transition properties of\\u000a different complex networks will be

Richard Berkovits; Lukas Jahnke; Jan W. Kantelhardt

187

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

NASA Technical Reports Server (NTRS)

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

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

1986-01-01

188

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

SciTech Connect

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

Malakhovskii, A. V., E-mail: malakha@iph.krasn.ru [Russian Academy of Sciences, L. V. Kirensky Institute of Physics Siberian Branch (Russian Federation); Gnatchenko, S. L.; Kachur, I. S.; Piryatinskaya, V. G. [National Academy of Sciences of Ukraine, B. Verkin Institute for Low Temperature Physics and Engineering (Ukraine)] [National Academy of Sciences of Ukraine, B. Verkin Institute for Low Temperature Physics and Engineering (Ukraine); Sukhachev, A. L.; Sokolov, A. E.; Strokova, A. Ya.; Kartashev, A. V.; Temerov, V. L. [Russian Academy of Sciences, L. V. Kirensky Institute of Physics Siberian Branch (Russian Federation)] [Russian Academy of Sciences, L. V. Kirensky Institute of Physics Siberian Branch (Russian Federation)

2013-01-15

189

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

SciTech Connect

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. [Max Planck Institute for Plasma Physics, EURATOM Association, Boltzmannstr. 2, 85748 Garching (Germany)] [Max Planck Institute for Plasma Physics, EURATOM Association, Boltzmannstr. 2, 85748 Garching (Germany)

2013-08-15

190

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

191

CaMKII locally encodes L-type channel activity to signal to nuclear CREB in excitation-transcription coupling.  

PubMed

Communication between cell surface proteins and the nucleus is integral to many cellular adaptations. In the case of ion channels in excitable cells, the dynamics of signaling to the nucleus are particularly important because the natural stimulus, surface membrane depolarization, is rapidly pulsatile. To better understand excitation-transcription coupling we characterized the dependence of cAMP response element-binding protein phosphorylation, a critical step in neuronal plasticity, on the level and duration of membrane depolarization. We find that signaling strength is steeply dependent on depolarization, with sensitivity far greater than hitherto recognized. In contrast, graded blockade of the Ca(2+) channel pore has a remarkably mild effect, although some Ca(2+) entry is absolutely required. Our data indicate that Ca(2+)/CaM-dependent protein kinase II acting near the channel couples local Ca(2+) rises to signal transduction, encoding the frequency of Ca(2+) channel openings rather than integrated Ca(2+) flux-a form of digital logic. PMID:19047462

Wheeler, Damian G; Barrett, Curtis F; Groth, Rachel D; Safa, Parsa; Tsien, Richard W

2008-12-01

192

Influence of trans and cis defects on the localization of charged excitations in ?-conjugated organic polymers  

NASA Astrophysics Data System (ADS)

Optoelectronic devices with ?-conjugated polymers are in demand for use in light-emitting diodes (LED), solar cells and lasers. A recent study predicted differences in the response of the hyperfine field by polaronic species in organic LEDs. The improved fluorescence exhibited by different isomeric forms of PPV derivatives in these devices motivated us to investigate the influence of various conformational defects of trans and cis nature on the energetics and localization of positive (P^+) and negative (P^-) polarons using density functional theory. We observe the P^+ and P^- states are highly sensitive on the structural conformation and atomic charge distributions. The P^- state is observed to be more localized than P^+in consistent with recent experiments when the polarization effects are included. These defects not only break the particle-hole symmetry but demonstrate higher charge-carrier mobilities for holes than electrons. This helps in tuning the charge-transport and photo-physical properties of organic materials by understanding their structure-property correlations for technological innovations.

Nayyar, Iffat; Batista, Enrique; Tretiak, Sergei; Saxena, Avadh; Smith, Darryl; Martin, Richard

2013-03-01

193

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

PubMed

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

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

2014-07-01

194

Revisitation of the localized excitations of the (2+1)-dimensional KdV equation  

NASA Astrophysics Data System (ADS)

In a previous paper (Lou S-y 1995 J. Phys. A: Math. Gen. 28 7227), a generalized dromion structure was revealed for the (2+1)-dimensional KdV equation, which was first derived by Boiti et al (Boiti M, Leon J J P, Manna M and Pempinelli F 1986 Inverse Problems 2 271) using the idea of the weak Lax pair. In this paper, using a Bäcklund transformation and the variable separation approach, we find there exist much more abundant localized structures for the (2+1)-dimensional KdV equation. The abundance of the localized structures of the model is introduced by the entrance of an arbitrary function of the seed solution. Some special types of dromion solution, lumps, breathers, instantons and the ring type of soliton, are discussed by selecting the arbitrary functions appropriately. The dromion solutions can be driven by sets of straight-line and curved-line ghost solitons. The dromion solutions may be located not only at the cross points of the lines but also at the closed points of the curves. The breathers may breathe both in amplitude and in shape.

Lou, Sen-yue; Ruan, H.-y.

2001-01-01

195

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

196

Electron transport near the Anderson transition  

NASA Astrophysics Data System (ADS)

In this work we examined the probability distribution of conductances in three dimensional metals for signatures of the Anderson transition. To that end, we examined the generalized DMPK equation in the insulating state and developed a formalism to perturbatively calculate the solution. From the solution we calculated the probability distribution of the conductance (g), and found excellent agreement with numerical simulations using the Anderson model. We also verified that the variance of lng varies with average of -lng to the two-fifths power, in congruence with earlier numerical studies. Though not definitive, calculations give no evidence of a singularity in the distribution near g = 1, in contrast to the behavior in quasi-one dimension.

Douglas, Andrew

197

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

198

Microwave excitation of localized electrons in phosphorus-doped silicon single electron transistors  

NASA Astrophysics Data System (ADS)

We investigate the effect of microwave irradiation on the source-drain current of a silicon single electron transistor, with fixed source-drain and gate voltages, at a temperature of 4 K. The source-drain current can be increased, decreased, or even reversed by the radiation, depending on the microwave frequency and dc bias conditions. Some of the source-drain current changes take the form of sharp resonances with high quality factor. We investigate the effect of the microwave irradiation coupling method on the form of these resonances. The coupling method does not modify the center frequency of the resonances however it does alter the resonance shape. We discuss the origin of these resonant features and propose that they originate from the microwave induced spatial redistributions of localized electrons in the single electron transistor.

Creswell, L. A.; Hasko, D. G.; Williams, D. A.

2009-05-01

199

Boson localization and excitations of liquid He4 confined in gelsil  

NASA Astrophysics Data System (ADS)

We present neutron scattering measurements of the phonon-roton (P-R) modes of liquid He4 at saturated vapor pressure confined in 44Å mean pore diameter gelsil in the wave vector range 0.4?Q?2.15Å-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?1.95Å-1) but not at Q?1.7Å-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 He4 , the P-R and layer modes are first observed at a fractional filling of f=76% at low temperature (T=0.4K) . At fillings f=76% , the P-R mode energies lie below the bulk superfluid He4 values in the wave vector range 0.4?Q?1.7Å-1 , especially at Q?1.1Å-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 Tc=1.92K is independently known and lies well below the bulk liquid value T?=2.17K . 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?2.15K , above Tc=1.92K . Since well-defined modes exist because there is Bose-Einstein condensation (BEC), this suggests that there is BEC above Tc , probably localized. Localized BEC appears to exist up to T?T? .

Albergamo, Francesco; Bossy, Jacques; Pearce, Jonathan V.; Schober, Helmut; Glyde, Henry R.

2007-08-01

200

Local Control Model of Excitation-Contraction Coupling in Skeletal Muscle  

PubMed Central

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

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

1997-01-01

201

Photoluminescence Under XUV Excitation Plus a Method of Dipole Summation for Local Fields Calculations.  

NASA Astrophysics Data System (ADS)

Organic and inorganic phosphors have often been used in detectors as a method of converting soft x-rays into visible light, which can then be detected by such devices as photodiodes and CCD's. However, the energy dependence of photoluminescent efficiency has been poorly known. This dissertation reports measurements of photoluminescence as a function of energy from 11 to 450 eV for the phosphors yttrium oxysulfide (Y_2O _2S:Eu), yttrium oxide (Y_2 O_3:Eu), lanthanum oxysulfide (La_2O_2S:Tm), gadolinium oxysulfide (Gd_2O _2S:Tb), and strontium chlorophosphate (Sr _5Cl(PO_4_)3 :Eu). With inelastic electron scattering spectroscopy, the optical properties of these phosphors have also been measured from 2 to 160 eV. Using the measured absorption and reflection coefficients and a model originally derived by H. B. DeVore for semiconductors, it is shown that the major cause of structure in the soft x-ray efficiency of phosphors in this energy range is surface recombination of charge carriers. The efficiency vs. photon energy and change of efficiency vs. total photon dose of an organic phosphor, para-terphenyl, have also been measured. It is found that the data cannot be modeled with the Birks -Black function for quenching of luminescence. A new variation of the Birks-Black function is developed. This function and an empirical function are used to model the damage data, and show that the damage rate goes as approximately the second power of the energy of the incident photons causing the damage. In the second part of this dissertation, a new method for computing momentum-dependent local fields is described. This method makes it possible to relatively quickly perform the dipole summations necessary for calculating the B(q) function for tetragonal lattices, including complex perovskites. Some results are demonstrated for aspect ratios of a simple lattice and for the perovskite structures of two high-temperature superconductors.

Benitez, Eva Lopdrup

202

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,...

203

Local plasticity of dendritic excitability can be autonomous of synaptic plasticity and regulated by activity-based phosphorylation of Kv4.2.  

PubMed

While plasticity is typically associated with persistent modifications of synaptic strengths, recent studies indicated that modulations of dendritic excitability may form the other part of the engram and dynamically affect computational processing and output of neuronal circuits. However it remains unknown whether modulation of dendritic excitability is controlled by synaptic changes or whether it can be distinct from them. Here we report the first observation of the induction of a persistent plastic decrease in dendritic excitability decoupled from synaptic stimulation, which is localized and purely activity-based. In rats this local plasticity decrease is conferred by CamKII mediated phosphorylation of A-type potassium channels upon interaction of a back propagating action potential (bAP) with dendritic depolarization. PMID:24404150

Labno, Anna; Warrier, Ajithkumar; Wang, Sheng; Zhang, Xiang

2014-01-01

204

Mineralocorticoid receptor blocker eplerenone reduces pain behaviors in vivo and decreases excitability in small diameter sensory neurons from local inflamed dorsal root ganglia in vitro  

PubMed Central

Background Inflammation of the dorsal root ganglia (DRG) may contribute to low back pain, postherpetic neuralgia, and neuropathic pain. The mineralocorticoid receptor (MR) plays a pro-inflammatory role in many non-renal tissues, but its role in peripheral pain at the DRG level is not well studied. Methods Local inflammation of the L5 DRG with the immune activator zymosan rapidly leads to mechanical hypersensitivity and increased excitability of sensory neurons. Using this pain model, we applied the MR antagonist eplerenone locally to the inflamed DRG. Excitability of small diameter sensory neurons was examined in acute primary culture, using patch clamp techniques. Results Local eplerenone significantly reduced the mechanical hypersensitivity and shortened its duration. The same dose was ineffective systemically. Immunohistochemical studies showed the MR was present in most neurons, and rapidly translocated to the nucleus 1 day after local DRG inflammation. Activation of satellite glia (defined by expression of glial fibrillary acidic protein) in the inflamed DRG was also reduced by local eplerenone. Increased excitability of small diameter sensory neurons 1 day after inflammation could be observed in vitro. Eplerenone applied in vitro (8 – 12 hours) could reverse this increased excitability. Eplerenone had no effect in neurons isolated from normal, uninflamed DRG. The MR agonist aldosterone (10 nM) applied in vitro increased excitability of neurons isolated from normal DRG. Conclusions The MR may have a pro-nociceptive role in the DRG. Some of its effects may be mediated by neuronal MR. The MR may represent a novel therapeutic target in some pain syndromes.

Dong, Fei; Xie, Wenrui; Strong, Judith A.; Zhang, Jun-Ming

2012-01-01

205

On Mott's formula for the ac-conductivity in the Anderson model  

Microsoft Academic Search

We study the ac-conductivity in linear response theory in the general framework of ergodic magnetic Schrodinger operators. For the Anderson model, if the Fermi energy lies in the localization regime, we prove that the ac-conductivity is bounded by C?2(log 1 ?) d+2 at small frequencies ?. This is to be compared to Mott's formula, which predicts the leading term to

Abel Klein; Olivier Lenoble; Peter M

2006-01-01

206

Critical exponent for the Anderson transition in the three-dimensional orthogonal universality class  

NASA Astrophysics Data System (ADS)

We report a careful finite size scaling study of the metal-insulator transition in Anderson's model of localization. We focus on the estimation of the critical exponent ? that describes the divergence of the localization length. We verify the universality of this critical exponent for three different distributions of the random potential: box, normal and Cauchy. Our results for the critical exponent are consistent with the measured values obtained in experiments on the dynamical localization transition in the quantum kicked rotor realized in a cold atomic gas.

Slevin, Keith; Ohtsuki, Tomi

2014-01-01

207

Localization and Critical Diffusion of Quantum Dipoles in Two Dimensions  

NASA Astrophysics Data System (ADS)

We discuss quantum propagation of dipole excitations in two dimensions. This problem differs from the conventional Anderson localization due to the existence of long-range hops. We find that the critical wave functions of the dipoles always exist which manifest themselves by a scale independent diffusion constant. If the system is T invariant the states are critical for all values of the parameters. Otherwise, there can be a “metal-insulator” transition between this “ordinary” diffusion and the Levy flights (the diffusion constant logarithmically increasing with the scale). These results follow from the two-loop analysis of the modified nonlinear supermatrix ? model.

Aleiner, I. L.; Altshuler, B. L.; Efetov, K. B.

2011-08-01

208

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

209

On the Lower Critical Dimension of the Edwards-Anderson Spin Glass  

NASA Astrophysics Data System (ADS)

The Edwards-Anderson model of Spin Glasses is studied on dilute hyper-cubic lattices in dimensions d=2,3,,. Accurate predictions for the stiffness exponent yd are obtained that describes low-energy excitations. Continuing yd off the integers shows that its zero is located at d=5/2 to within 0.1%, a prediction that is corroborated by other numerical and theoretical work. Related Publication: Phys. Rev. Lett. 95, 197205 (2005). Related Webpage: http://www.physics.emory.edu/faculty/boettcher/ .

Boettcher, Stefan

2006-03-01

210

Aligning a reflection cavity by Anderson's method.  

PubMed

The sounding rocket principle of equivalence measurement uses a set of four laser gauges operating in Fabry-Perot cavities to determine the relative acceleration of two test masses that are chemically different. One end of each cavity is a flat mirror on a test mass. Because the test masses are unconstrained and thus expected to rotate slightly during measurement, and because the distance measurements are made at the sub-picometer level, it is essential to have real-time alignment of the beam entering the cavity. However, the cavity must be used in reflection and space is limited. We show that Anderson's alignment method can be used in reflection, but that it requires that the Fabry-Perot cavity have mirrors with significantly unequal reflectivities. PMID:22695543

Reasenberg, Robert D

2012-06-01

211

H2 Excitation Structure on the Sightlines to ? Scorpii and ? Ophiuci: First Results from the Sub-orbital Local Interstellar Cloud Experiment  

NASA Astrophysics Data System (ADS)

We present the first science results from the Sub-orbital Local Interstellar Cloud Experiment (SLICE): moderate resolution 1020-1070 Å spectroscopy of four sightlines through the local interstellar medium. High signal-to-noise (S/N) spectra of ? Uma, ? Vir, ? Sco, and ? Oph were obtained during a 2013 April 21 rocket flight. The SLICE observations constrain the density, molecular photoexcitation rates, and physical conditions present in the interstellar material toward ? Sco and ? Oph. Our spectra indicate a factor of two lower total N(H2) than previously reported for ? Sco, which we attribute to higher S/N and better scattered light control in the new SLICE observations. We find N(H2) = 1.5 × 1019 cm-2 on the ? Sco sightline, with kinetic and excitation temperatures of 67 and 529 K, respectively, and a cloud density of n H = 56 cm-3. Our observations of the bulk of the molecular sightline toward ? Oph are consistent with previous measurements (N(H2) ? 3 × 1020 cm-2 at T 01(H2) = 66 K and T exc = 350 K). However, we detect significantly more rotationally excited H2 toward ? Oph than previously observed. We infer a cloud density in the rotationally excited component of n H ? 7600 cm-3 and suggest that the increased column densities of excited H2 are a result of the ongoing interaction between ? Oph and its environment; also manifest as the prominent mid-IR bowshock observed by WISE and the presence of vibrationally excited H2 molecules observed by the Hubble Space Telescope.

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

2013-07-01

212

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

SciTech Connect

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

France, Kevin; Nell, Nicholas; Kane, Robert; Green, James C. [Center for Astrophysics and Space Astronomy, University of Colorado, 389 UCB, Boulder, CO 80309 (United States); Burgh, Eric B. [SOFIA/USRA, NASA Ames Research Center, M/S N232-12, Moffett Field, CA 94035 (United States); Beasley, Matthew, E-mail: kevin.france@colorado.edu [Planetary Resources, Inc., 93 S Jackson St 50680, Seattle, WA 98104-2818 (United States)

2013-07-20

213

Hay Lake Specialist's Report: Anderson Mesa Landscape Scale Assessment.  

National Technical Information Service (NTIS)

The Anderson Mesa Landscape Scale Assessment is a comprehensive document that describes the ecosystems structure, processes and functions. The Assessment objectives as outlined in the project initiation letter were as follows: Identify opportunities (proj...

2004-01-01

214

STS-107 M.S Michael Anderson at SPACEHAB  

NASA Technical Reports Server (NTRS)

KENNEDY SPACE CENTER, FLA. -- At SPACEHAB, STS-107 Mission Specialist Michael Anderson (gloved, in center) gets hands-on experience with equipment. Identified as a research mission, STS-107 is scheduled for launch July 19, 2001

2000-01-01

215

MD Anderson study finds cancer related pain often undertreated  

Cancer.gov

More than one third of patients with invasive cancer are undertreated for their pain, with minorities twice as likely to not receive analgesics, according to research from The University of Texas MD Anderson Cancer Center.

216

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

217

Anderson-Fabry disease in children.  

PubMed

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

Sestito, Simona; Ceravolo, Ferdinando; Concolino, Daniela

2013-01-01

218

Localized Hartree-Fock density-functional calculations of singly, doubly, and triply excited Rydberg states of He- and Li- like ions  

NASA Astrophysics Data System (ADS)

An exact spin-dependent localized Hartree-Fock (LHF) exchange potential is derived for both close-shell and open-shell of atomic systems. The LHF exchange potential is free of the Coulomb self-interaction, has the correct long-range behavior, requires only the occupied orbitals, and thus implies the requirements for the investigation of the excited states. An effective procedure of the exact exchange density-functional theory (DFT), the spin-polarized LHF density-functional method, is presented based on the LHF exchange potential for the multiply excited states of the atomic systems. This method is applied to the calculations of singly, doubly, and especially triply excited Rydberg states of He- and Li- like ions. The exchange-only (X-only) results are found to be surprisingly close to those of the Hartree-Fock (HF) method. The correlation effects are considered by incorporating the Lee-Yang-Parr (LYP) correlation potential into the LHF exchange potential. The results are in overall agreement with the available theoretical and experimental data in light of the typical errors of the DFT calculations of the excited states.

Zhou, Zhongyuan; Chu, Shih-I.

2004-05-01

219

Resonance induced by a bound state in the continuum in a two-level nonlinear Fano-Anderson model  

NASA Astrophysics Data System (ADS)

We consider the transmission through a nonlinear media in the framework of a two-level nonlinear Fano-Anderson model. The model is realized in photonic crystal waveguide coupled with two off-channel defects with the instantaneous Kerr-type nonlinearity. We reveal a resonance and argue that it is a result of excitement of bound state in the continuum (BSC) by transmitted wave. The resonance induced by BSC is located at the energy of BSC with a width proportional to the amplitude of incident wave. The BSC exists at any distance between energy levels of the two-level nonlinear Fano-Anderson model that is fundamentally different from the linear case.

Bulgakov, Evgeny N.; Sadreev, Almas F.

2009-09-01

220

Pu 4f XPS spectra analyzed in the Anderson impurity model  

NASA Astrophysics Data System (ADS)

X-ray photoemission spectra of the ?, ?, ?, and ? phases of Pu have been analyzed using the Gunnarsson-Schönhammer implementation of the Anderson impurity model. Changes in the relative spectral weights of the two features representing mixed f 5 and f 6 final states are in reasonable agreement with the model's predictions. The Coulomb terms, Uff and Ufc, are quite consistent with those derived from atomic and LDA calculations. Multiplet structure, which agrees with atomic calculations for 4f 135f 5, strongly suggests 5f localization in the final state.

Cox, L. E.; Peek, J. M.; Allen, J. W.

1999-01-01

221

Ground-state of the single impurity Anderson model with correlated conduction electrons  

NASA Astrophysics Data System (ADS)

Utilizing the nonperturbative Lanczos procedure, we study the ground-state spectrum of the Single-Impurity Anderson Model. An additional term is added to the Hamiltonian which represents a Coulomb-repulsion between the conduction electrons. The ground-state energy as well as the singlet-triplet energy is calculated in this strongly interacting system. Our results are consistent with those of Fermi-liquid theory which predicts a renormalization of the low energy properties of the system upon introduction of local, repulsive conduction electron interactions.

Fessatidis, Vassilios; Mancini, Jay D.; Massano, William J.; Bowen, Samuel P.

2002-10-01

222

Mottness scenario for non-Fermi liquid behavior in the periodic Anderson model within dynamical mean-field theory  

Microsoft Academic Search

We study the Mott metal-insulator transition in the periodic Anderson model within dynamical mean-field Theory (DMFT). Near the quantum transition, we find a non-Fermi liquid metallic state down to a vanishing temperature scale. We identify the origin of the non-Fermi liquid behavior as due to magnetic scattering of the doped carriers by the localized moments. The non-Fermi liquid state can

Giovanni Sordi; Adriano Amaricci; Marcelo Rozenberg

2009-01-01

223

STS-89 M.S. Michael Anderson suits up  

NASA Technical Reports Server (NTRS)

STS-89 Mission Specialist Michael Anderson smiles as he completes the donning of his launch/entry suit in the Operations and Checkout (O&C) Building. A major in the U.S. Air Force, Anderson has a master of science degree in physics from Creighton University. He and six fellow crew members will soon depart the O&C and head for Launch Pad 39A, where the Space Shuttle Endeavour will lift off during a launch window that opens at 9:43 p.m. EST, Jan. 22. STS-89 is the eighth of nine planned missions to dock the Space Shuttle with Russia's Mir space station.

1998-01-01

224

Phase Shift of the Asymmetric Friedel-Anderson Impurity  

NASA Astrophysics Data System (ADS)

The ground state of the asymmetric Friedel-Anderson (aFA) impurity is calculated within the FAIR (Friedel artificially inserted resonance) theory. Its properties are investigated by means of the fidelity with different Friedel impurities and by its Friedel oscillations. Friedel impurities with a specific phase shift ? at the Fermi level possess a finite fidelity with the aFA impurity. This phase shift ? determines other properties of the aFA impurity such as the amplitude and displacement of its Friedel oscillations. One can find the parameters of a Friedel impurity which coincides in its Friedel oscillations almost perfectly with the aFA impurity, thereby avoiding an Anderson orthogonality catastrophe.

Bergmann, Gerd

2013-04-01

225

Three-Dimensional Numerical Simulation on Passively Excited Flows by Distributed Local Hot Sources Settled at the D  

Microsoft Academic Search

To unveil dynamic process associated with three-dimensional unsteady mantle convection, we carried out numerical simulation on passively exerted flows by simplified local hot sources just above the CMB and large-scale cool masses beneath smoothed subduction zones. During the study, we used our individual code developed with the finite difference method. The basic three equations are for the continuity, the motion

T. Eguchi; K. Matsubara; M. Ishida

2001-01-01

226

How to Use a Bed of Nails to Facilitate Excitement during a Science Road Show Presentation at Local Schools  

NASA Astrophysics Data System (ADS)

The authors will demonstrate how to use a bed of nails to pump up the students at local K-12 schools. The use during Science Road Show presentations will be addressed along with suggestions on how to build the drama and introduce humor and learning.

Pena, Fabian; Kridler, Shawn; Berger, Pete

2008-03-01

227

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

228

Ultracytochemical localization of acetylcholine-like cations in excited motor end-plates by means of ionic fixation  

Microsoft Academic Search

Summary  Using rapid ionic fixation with molybdic or tungstic heteropolyanions (strong precipitating agents of quaternary ammonium\\u000a cations such as choline and acetylcholine), acetylcholine-like cations were localized aspoint-like precipitates in the synaptic vesicles of resting (electrically nonstimulated) motor nerve terminals. When performed\\u000a at low temperature, the same procedure revealedspot-like precipitates (presumed to be exocytotically released acetylcholine-like cations) in the synaptic cleft in

S. Tsuji

1985-01-01

229

CONDENSED MATTER: ELECTRONIC STRUCTURE, ELECTRICAL, MAGNETIC, AND OPTICAL PROPERTIES: Parametrization of Transfer Matrix: for One-Dimensional Anderson Model with Diagonal Disorder  

NASA Astrophysics Data System (ADS)

In this paper, we developed a new parametrization method to calculate the localization length in one-dimensional Anderson model with diagonal disorder. This method can avoid the divergence difficulty encountered in the conventional methods, and significantly save computing time as well.

Kang, Kai; Qin, Shao-Jing; Wang, Chui-Lin

2010-10-01

230

Markovian Anderson Model: Bounds for the Rate of Propagation  

NASA Astrophysics Data System (ADS)

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

Tcheremchantsev, Serguei

231

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

232

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

233

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

234

Solar Hot Water System Installed at Anderson, South Carolina.  

National Technical Information Service (NTIS)

A description is given of the solar energy hot water system installed in the Days Inns of America, Inc., at Anderson, South Carolina. The building is a low-rise, two-story 114-room motel. The solar system was designed to provide 40 percent of the total ho...

1978-01-01

235

Electronic Excitation Spectra from All-Electron Non-Local Screened Exchange Density Functional Theory: FLAPW Implementation and Applications to Semiconductors, Metals, and Insulators  

NASA Astrophysics Data System (ADS)

The accurate description of electronic excitations for solids including semiconductors, transition metals, and f-electron systems continues to be a major challenge. Recently, Bylander and Kleinman (D. M. Bylander and L. Kleinman, Phys. Rev. B 41), 7868 (1990) and Seidl et al. (A. Seidl, A. Görling, P. Vogl, J. A. Majewski, and M. Levy, Phys. Rev. B 53), 3764 (1996) have explored a non-local screened-exchange (sX) approach within a pseudopotential implementation. In order to overcome the limitations of pseudopotentials (treatment of f-electrons, magnetic systems, spin-orbit relativistic effects), we have implemented the sX approach in the full-potential linearized augmented plane wave (FLAPW) method (H. J. F. Jansen and A. J. Freeman, Phys. Rev. B 30), 561 (1984); S. Massidda et al., Phys. Rev. B 48, 5058 (1993). Results will be presented for elemental and compound semiconductors, transition metals and their compounds, and f-electron systems.

Wolf, Walter; Wimmer, Erich; Massidda, Sandro; Posternak, Michel; Geller, Clint B.

1998-03-01

236

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

PubMed

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 10(6) 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. PMID:24229117

Chamberlin, Ralph V; Davis, Bryce F

2013-10-01

237

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

238

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

239

Quantum critical phase and Lifshitz transition in an extended periodic Anderson model.  

PubMed

We study the quantum phase transition in f-electron systems as a quantum Lifshitz transition driven by selective-Mott localization in a realistic extended Anderson lattice model. Using dynamical mean-field theory (DMFT), we find that a quantum critical phase with anomalous ?/T scaling separates a heavy Landau-Fermi liquid from ordered phase(s). This non-Fermi liquid state arises from a lattice orthogonality catastrophe originating from orbital-selective Mott localization. Fermi surface reconstruction occurs via the interplay between and penetration of the Green function zeros to the poles, leading to violation of Luttinger's theorem in the strange metal. We show how this naturally leads to scale-invariant responses in transport. Thus, our work represents a specific DMFT realization of the hidden-FL and FL* theories, and holds promise for the study of 'strange' metal phases in quantum matter. PMID:22589244

Laad, M S; Koley, S; Taraphder, A

2012-06-13

240

Numerical study of the topological Anderson insulator in HgTe/CdTe quantum wells  

NASA Astrophysics Data System (ADS)

We study the disorder effect on the transport properties in the HgTe/CdTe semiconductor quantum wells. We confirm that at a moderate disorder strength, the initially unquantized two-terminal conductance becomes quantized and the system makes a transition to the topological Anderson insulator (TAI). Conductances calculated for the stripe and cylinder samples reveal the topological feature of TAI and supports the idea that the helical edge states may cause the anomalous quantized plateaus. The influence of disorder is studied by calculating the distributions of local currents. Based on the above-mentioned picture, the phenomena induced by disorder in the quantum spin-Hall region and TAI region are directly explained. Our study of the local-current configurations shed further light on the mechanism of the anomalous plateau.

Jiang, Hua; Wang, Lei; Sun, Qing-Feng; Xie, X. C.

2009-10-01

241

Metastable de-excitation spectroscopy study on the local valence-electron states of the K/Si(100)2 × 1 surface  

NASA Astrophysics Data System (ADS)

The local electronic structure of a potassium adlayer on the Si(100)2 × 1 surface has been studied by metastable de-excitation spectroscopy (MDS), combined with surface characterization by Auger electron spectroscopy and work function variation. MDS spectra from K-adsorbed surfaces in the whole coverage region upto saturation exhibited a sharp peak just below EF originated mainly from the K 4s states. This finding strongly disagrees with the theoretical viewpoint of full ionization of adsorbed alkali-metal atoms by Ciraci and Batra. The MDS intensity for the K 4s-derived states increased rapidly with increasing K coverage ? K at around 0.4. It reached a maximum at ? K ? 0.7, which is followed by a small decrease towards ? K = 1.0. This tendency clearly demonstrates the large variation in the local density of the K 4s-derived states dependent upon coverage. Work function variation for the K/Si(100) system has been explained in terms of adsorption-induced redistribution of valence electrons.

Nishigaki, S.; Matsuda, S.; Sasaki, T.; Kawanishi, N.; Ikeda, Y.; Takeda, H.

1990-05-01

242

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

243

STS-107 Crew Interviews: Michael Anderson, Mission Specialist  

NASA Technical Reports Server (NTRS)

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

2002-01-01

244

STS-107 Crew Interviews: Michael Anderson, Mission Specialist  

NASA Astrophysics Data System (ADS)

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

2002-06-01

245

STS-107 Payload Commander Michael Anderson suits up for TCDT  

NASA Technical Reports Server (NTRS)

KENNEDY SPACE CENTER, FLA. -- STS-107 Payload Commander Michael Anderson completes suit check prior to Terminal Countdown Demonstration Test activities, which include a simulated launch countdown at the pad. STS-107 is a mission devoted to research and will include more than 80 experiments that will study Earth and space science, advanced technology development, and astronaut health and safety. Launch is planned for Jan. 16, 2003, between 10 a.m. and 2 p.m. EST aboard Space Shuttle Columbia. .

2002-01-01

246

The S=1 Underscreened Anderson Lattice model for Uranium compounds  

Microsoft Academic Search

Magnetic properties of uranium and neptunium compounds showing coexistence of the Kondo effect and ferromagnetic order are investigated within the degenerate Anderson Lattice Hamiltonian, describing a 5f2 electronic configuration with S = 1 spins. Through the Schrieffer-Wolff transformation, both an exchange Kondo interaction for the S = 1 f-spins and an effective f-band term are obtained, allowing to describe the

C. Thomas; A. S. R. Simões; J. R. Iglesias; C. Lacroix; N. B. Perkins; B. Coqblin

2011-01-01

247

The canonical transformation method in the periodic Anderson model  

Microsoft Academic Search

We investigate a version of the periodic Anderson model in which both the d- and f-electron subsystems are strongly correlated.\\u000a The one-site hybridization of the electron quantum states in each subsystem and the possibility of the d-electron hopping\\u000a between lattice sites are taken into account. To construct the canonical transformation S-matrix, we use the system of one-site\\u000a orthonormalized functions belonging

V. A. Moskalenko; N. B. Perkins

1999-01-01

248

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

249

Solar hot water system installed at Anderson, South Carolina  

NASA Technical Reports Server (NTRS)

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

1978-01-01

250

UT MD Anderson scientists discover secret life of chromatin:  

Cancer.gov

Chromatin--the intertwined histone proteins and DNA that make up chromosomes--constantly receives messages that pour in from a cell’s intricate signaling networks... But chromatin also talks back, scientists at The University of Texas M.D. Anderson Cancer Center report today in the journal Cell, issuing orders affecting a protein that has nothing to do with chromatin’s central role in gene transcription--the first step in protein formation.

251

Moment closure of the relativistic Anderson and Witting model equation  

NASA Astrophysics Data System (ADS)

It is shown that the closure of the model equation of Anderson and Witting by a moment method leads to transport coefficients of a relativistic gas which differ from those obtained by the usual Chapman and Enskog method. The transport coefficients obtained in the two closures coincide in the non-relativistic limiting case but depart from each other in the relativistic and ultra-relativistic regions.

Cercignani, C.; Kremer, G. M.

2001-02-01

252

Topological Anderson insulator induced by inter-cell hopping disorder  

NASA Astrophysics Data System (ADS)

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

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

2013-11-01

253

Plasminogen activator inhibitor-2 (PAI-2) mRNA is localized in the accumbens nucleus of the mouse brain and is induced in specific brain sites after kainate excitation ? ? Published on the World Wide Web on 3 January 2001  

Microsoft Academic Search

Plasminogen activator inhibitor-2 (PAI-2) specifically inhibits plasminogen activators, extracellular fibrinolytic serine proteases that are also implicated in brain plasticity and toxicity. Primarily localized intracellularly, PAI-2 is thought to also counteract apoptosis mediated by a currently undefined intracellular protease. Here we localized PAI-2 mRNA through in situ hybridization in brain cryosections derived from normal adult mice or after kainate excitation. We

Ronit Sharon; Rene Abramovitz; Ruth Miskin

2001-01-01

254

Localized excitations in competing bond-order-wave, charge-density-wave and spin-density-wave systems II: Competing charge-density-wave and spin-density-wave.  

National Technical Information Service (NTIS)

The extended Peierls-Hubbard model is used to study the competition of the spin-density-wave (SDW) and charge-density-wave (CDW) states as well as the attendant localized excitations in quasi-one-dimensional systems like MX-chains. The ground state proper...

W. Wang Z. Su L. Yu C. Wang

1992-01-01

255

Effective cluster typical medium theory for the diagonal Anderson disorder model in one- and two-dimensions.  

PubMed

We develop a cluster typical medium theory to study localization in disordered electronic systems. Our formalism is able to incorporate non-local correlations beyond the local typical medium theory in a systematic way. The cluster typical medium theory utilizes the momentum-resolved typical density of states and hybridization function to characterize the localization transition. We apply the formalism to the Anderson model of localization in one- and two-dimensions. In one-dimension, we find that the critical disorder strength scales inversely with the linear cluster size with a power law, Wc ? (1/Lc)(1/?), whereas in two-dimensions, the critical disorder strength decreases logarithmically with the linear cluster size. Our results are consistent with previous numerical work and are in agreement with the one-parameter scaling theory. PMID:24934293

Ekuma, Chinedu E; Terletska, Hanna; Meng, Zi Yang; Moreno, Juana; Jarrell, Mark; Mahmoudian, Samiyeh; Dobrosavljevi?, Vladimir

2014-07-01

256

Role of band structure and local-field effects in the low-energy collective electronic excitation spectra of 2H-NbSe2  

NASA Astrophysics Data System (ADS)

We present a study of the electron dynamics in the layered compound 2H-NbSe2. First-principles calculations are used to obtain the band structure employed in the evaluation of the loss function with inclusion of local-field (LF) effects. Two different symmetry directions [(100) and (010)] were explored in the hexagonal basal plane. In both cases, a low-energy charge-carrier plasmon (CCP) at ˜1 eV presenting a negative dispersion over a wide momentum transfer range is found, in agreement with recent experimental results [Wezel , Phys. Rev. Lett.PRLTAO0031-900710.1103/PhysRevLett.107.176404 107, 176404 (2011)]. On the contrary, in the (001) perpendicular direction, the CCP has negative dispersion at small momenta only, presenting strong positive dispersion at larger momenta. Our calculations reveal that this behavior can be explained without invoking many-body effects, as long as band structure effects are properly included in the evaluation of the excitation spectra. In addition to this CCP mode, we find another one with an arclike oscillating dispersion along the perpendicular direction, as well as the appearance of a CCP replica at high momenta due to LF effects.

Faraggi, M. N.; Arnau, A.; Silkin, V. M.

2012-07-01

257

Pu 4f XPS spectra analyzed in the Anderson impurity model  

SciTech Connect

X-ray photoemission spectra of the {alpha},{beta},{gamma}, and {delta} phases of Pu have been analyzed using the Gunnarsson-Schonhammer implementation of the Anderson impurity model. Changes in the relative intensities of the two spectral features representing mixed f{sup 5} and f{sup 6} final states are in reasonable agreement with the model`s predictions. The coulomb terms, U{sub ff} and U{sub fc}, are quite consistent with those derived from atomic and LDA calculations. Multiplet structure, which agrees with atomic calculations for 4f{sup 13}5f{sup 5}, strongly suggests 5f localization in the final state.

Cox, L.E.; Peek, J.M. [Los Alamos National Lab., NM (United States). Nuclear Materials Technology Div.; Allen, J.W. [Univ. of Michigan, Ann Arbor, MI (United States). Dept. of Physics

1998-05-09

258

Diagram theory for the periodic anderson model: Stationarity of the thermodynamic potential  

NASA Astrophysics Data System (ADS)

We develop a diagram theory for the periodic Anderson model assuming that the Coulomb repulsion of localized f electrons is the main parameter of the theory. The f electrons are strongly correlated and the c conduction electrons are uncorrelated. We determine the f-electron correlation function and the c-electron mass operator. We formulate the Dyson equation for c electrons and a Dyson-type equation for f electrons and their propagators. We define the skeleton diagrams for the correlation function and the thermodynamic functional. We establish the stationarity of the renormalized thermodynamic potential under variation of the mass operator. The obtained results are applicable to both the normal and the superconducting system states.

Moskalenko, V. A.; Dohotaru, L. A.; Citro, R.

2010-03-01

259

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

260

Cryogenic exciter  

DOEpatents

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

261

STS-107 Payload Commander Michael Anderson suits up for TCDT  

NASA Technical Reports Server (NTRS)

KENNEDY SPACE CENTER, FLA. - STS-107 Payload Commander Michael Anderson smiles as he undergoes suit check prior to Terminal Countdown Demonstration Test activities, which include a simulated launch countdown at the pad. STS-107 is a mission devoted to research and will include more than 80 experiments that will study Earth and space science, advanced technology development, and astronaut health and safety. Launch is planned for Jan. 16, 2003, between 10 a.m. and 2 p.m. EST aboard Space Shuttle Columbia. .

2002-01-01

262

STS-107 Payload Commander Michael Anderson checks equipment at SPACEHAB  

NASA Technical Reports Server (NTRS)

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

2002-01-01

263

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

264

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

265

Calculations of generalized oscillator strength for electron-impact excitations of krypton and xenon using a relativistic local-density potential  

NASA Astrophysics Data System (ADS)

The generalized oscillator strength (GOS) of an atom is an essential factor in the differential cross section for inelastic scattering of fast charged particles. Recently, Takayanagi et al. [Phys. Rev. A 41, 5948 (1990)] have obtained the GOS for the excitation of atomic krypton to the 4p5(2P1/2)5s and 4p5(2P3/2)5s states from inelastic-scattering measurements using electron-energy-loss spectroscopy. The present study was undertaken with the twofold objective to determine the results of theoretical computations of the scattering parameters of the above experiment and to examine the suitability of a recently developed relativistic local-density-potential method [M. Vijayakumar, N. Vaidehi, and M. S. Gopinathan, Phys. Rev. A 40, 6834 (1989)] to study atomic-collision processes. Calculations have been done to obtain GOS for electron-krypton and electron-xenon collisions in the squared-momentum-transfer range of 0.01 to 10 atomic units. The well-known theory of Bethe has been used for the determination of the GOS in the first-order Born approximation. The present results are in fair agreement with previous Hartree-Slater and Hartree-Fock calculations and with the experimental data available in the literature. Furthermore, results of the present calculations predict that the GOS goes through a minimum, similar to the ``Cooper minimum'' in the photoabsorption cross section, as a function of the value of the momentum transfer. Experiments at slightly higher values of momentum transfer are suggested to verify the position of this minimum.

Padma, R.; Deshmukh, P. C.

1992-09-01

266

Calculations of generalized oscillator strength for electron-impact excitations of krypton and xenon using a relativistic local-density potential  

SciTech Connect

The generalized oscillator strength (GOS) of an atom is an essential factor in the differential cross section for inelastic scattering of fast charged particles. Recently, Takayanagi {ital et} {ital al}. (Phys. Rev. A 41, 5948 (1990)) have obtained the GOS for the excitation of atomic krypton to the 4{ital p}{sup 5}({sup 2}{ital P}{sub 1/2})5{ital s} and 4{ital p}{sup 5}({sup 2}{ital P}{sub 3/2})5{ital s} states from inelastic-scattering measurements using electron-energy-loss spectroscopy. The present study was undertaken with the twofold objective to determine the results of theoretical computations of the scattering parameters of the above experiment and to examine the suitability of a recently developed relativistic local-density-potential method (M. Vijayakumar, N. Vaidehi, and M. S. Gopinathan, Phys. Rev. A 40, 6834 (1989)) to study atomic-collision processes. Calculations have been done to obtain GOS for electron-krypton and electron-xenon collisions in the squared-momentum-transfer range of 0.01 to 10 atomic units. The well-known theory of Bethe has been used for the determination of the GOS in the first-order Born approximation. The present results are in fair agreement with previous Hartree-Slater and Hartree-Fock calculations and with the experimental data available in the literature. Furthermore, results of the present calculations predict that the GOS goes through a minimum, similar to the Cooper minimum'' in the photoabsorption cross section, as a function of the value of the momentum transfer. Experiments at slightly higher values of momentum transfer are suggested to verify the position of this minimum.

Padma, R.; Deshmukh, P.C. (Department of Physics, Indian Institute of Technology, Madras 600036 (India))

1992-09-01

267

Reply. [to the comment by Anderson et al. (1993)  

NASA Technical Reports Server (NTRS)

While Hegg et al. (1993) accepts the criticism of Anderson et al. (1994) in principle, this involves the adoption of an aerosol composition model and the model that they propose to reconcile these observations with the assertion of Charlson et al. (1992) does not agree with many observations, particularly those made over the North Atlantic Ocean. Although the use of a gain factor (i.e. the partial derivative of aerosol mass with respect to the sulfate ion), proposed by Anderson et al., may be valid for particular cases where a proposed composition model really reflects the actual aerosol composition, this procedure is considered questionable in general. The use of sulfate as a tracer for nonsulfate aerosol mass is questionable, because in the present authors' data set, sulfate averaged only about 26% of the dry aerosol mass. The ammonium mass associated with sulfate mass is not analogous to that betwen the oxygen mass and sulfur mass in the sulfate ion. Strong chemical bonds are present between sulfur and oxygen in sulfate, whereas ammonium and sulfate in haze droplets are ions in solution that may or may not be associated with one another. Thus, there is no reason to assume that sulfate will act as a reliable tracer of ammonium mass. Hegg et al. expresses the view that their approach used for estimating sulfate light scattering efficiency is appropriate for the current level of understanding of atmospheric aerosols.

Hegg, Dean A.; Ferek, Ronald G.; Hobbs, Peter V.

1994-01-01

268

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

269

Quantum criticality in the pseudogap two-channel Anderson and Kondo models  

NASA Astrophysics Data System (ADS)

The two-channel Anderson and Kondo impurity models with a density of states ?(E) |E|^r that vanishes at the Fermi energy (E=0) is of current interest in connection with impurities in graphene and in unconventional superconductors. The phase diagram of these models has been established previously [1,2]. We study the low-temperature static and dynamical properties of the models using the numerical renormalization-group method, and compare our results against exact and perturbative analytical theories [2], and against calculations performed within the non-crossing approximation. In the vicinity of the quantum critical points separating local-moment and non-Fermi liquid phases, the static local spin susceptibility is characterized by a set of critical exponents that satisfy the hyperscaling relations expected of an interacting system below its upper critical dimension. The dynamical local susceptibility and the impurity spectral function exhibit forms consistent with frequency-over-temperature scaling, another feature associated with interacting quantum critical points. [1] C. Gonzalez-Buxton and K. Ingersent, Phys. Rev. B 57, 14254 (1998). [2] I. Schneider et al., Phys. Rev. B, 84, 125139 (2011).

Chowdhury, Tathagata; Ingersent, Kevin; Zamani, Farzaneh; Ribeiro, Pedro; Kirchner, Stefan

2013-03-01

270

Charge-transfer correction for improved time-dependent local density approximation excited-state potential energy curves: Analysis within the two-level model with illustration for H2 and LiH  

NASA Astrophysics Data System (ADS)

Time-dependent density-functional theory (TDDFT) is an increasingly popular approach for calculating molecular excitation energies. However, the TDDFT lowest triplet excitation energy, ?T, of a closed-shell molecule often falls rapidly to zero and then becomes imaginary at large internuclear distances. We show that this unphysical behavior occurs because ?T2 must become negative wherever symmetry breaking lowers the energy of the ground state solution below that of the symmetry unbroken solution. We use the fact that the ?SCF method gives a qualitatively correct first triplet excited state to derive a ``charge-transfer correction'' (CTC) for the time-dependent local density approximation (TDLDA) within the two-level model and the Tamm-Dancoff approximation (TDA). Although this correction would not be needed for the exact exchange-correlation functional, it is evidently important for a correct description of molecular excited state potential energy surfaces in the TDLDA. As a byproduct of our analysis, we show why TDLDA and LDA ?SCF excitation energies are often very similar near the equilibrium geometries. The reasoning given here is fairly general and it is expected that similar corrections will be needed in the case of generalized gradient approximations and hybrid functionals.

Casida, Mark E.; Gutierrez, Fabien; Guan, Jingang; Gadea, Florent-Xavier; Salahub, Dennis; Daudey, Jean-Pierre

2000-11-01

271

Finite-size corrections for ground states of Edwards-Anderson spin glasses  

NASA Astrophysics Data System (ADS)

Extensive computations of ground-state energies of the Edwards-Anderson spin glass on bond-diluted, hypercubic lattices are conducted in dimensions d=3, ..., 7. Results are presented for bond densities exactly at the percolation threshold, p=pc, and deep within the glassy regime, p>pc, where finding ground states is one of the hardest combinatorial optimization problems. Finite-size corrections of the form 1/N? are shown to be consistent throughout with the prediction ?=1-y/d, where y refers to the "stiffness" exponent that controls the formation of domain wall excitations at low temperatures. At p=pc, an extrapolation for d?? appears to match our mean-field results for these corrections. In the glassy phase, however, ? does not approach its anticipated mean-field value of 2/3, obtained from simulations of the Sherrington-Kirkpatrick spin glass on an N-clique graph. Instead, the value of ? reached at the upper critical dimension matches another type of mean-field spin glass models, namely those on sparse random networks of regular degree called Bethe lattices.

Boettcher, Stefan; Falkner, Stefan

2012-05-01

272

Pu 4f XPS spectra analysed in Anderson impurity model  

NASA Astrophysics Data System (ADS)

Pu metal displays a sequence of phases, ?, ?, ?, ?, which involve changes in the 5f electronic structure. In the sequence, opposite to expectations in conventional band theory, the volume/Pu atom increases and yet the measured valence band 5f width also increases^1. We report an analysis of the systematic changes in the structured 4f core level XPS spectra^2 using an Anderson impurity model for the 5f electrons and discuss the implications for understanding the phase diagram. ^1 L.E. Cox et al, Phys. Rev. B 46, 13571 (1992). ^2 J.W. Allen et al, J. Electron. Spectrosc. Relat. Phenom., to be published. Supported at LANL by the DoE and at UM by the USDOE under Contract No. DE-FG-02-90ER45416 and by the NSF under Grant No. DMR-94-23741.

Allen, J. W.; Cox, L. E.; Peek, J. M.

1996-03-01

273

Kondo Destruction and Valence Fluctuations in an Anderson Model  

NASA Astrophysics Data System (ADS)

Unconventional quantum criticality in heavy-fermion systems has been extensively analyzed in terms of a critical destruction of the Kondo effect. Motivated by a recent demonstration of quantum criticality in a mixed-valent heavy-fermion system, ?-YbAlB4, we study a particle-hole-asymmetric Anderson impurity model with a pseudogapped density of states. We demonstrate Kondo destruction at a mixed-valent quantum critical point, where a collapsing Kondo energy scale is accompanied by a singular charge-fluctuation spectrum. Both spin and charge responses scale with energy over temperature (?/T) and magnetic field over temperature (H/T). Implications for unconventional quantum criticality in mixed-valence heavy fermions are discussed.

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

2012-08-01

274

Scaling between periodic Anderson and Kondo lattice models  

NASA Astrophysics Data System (ADS)

Continuous-time quantum Monte Carlo method combined with dynamical mean field theory is used to calculate both periodic Anderson model (PAM) and Kondo lattice model (KLM). Different parameter sets of both models are connected by the Schrieffer-Wolff transformation. For degeneracy N=2, a special particle-hole symmetric case of PAM at half filling which always fixes one electron per impurity site is compared with the results of the KLM. We find a good mapping between PAM and KLM in the limit of large on-site Hubbard interaction U for different properties like self-energy, quasiparticle residue and susceptibility. This allows us to extract quasiparticle mass renormalizations for the f electrons directly from KLM. The method is further applied to higher degenerate case and to realistic heavy fermion system CeRhIn5 in which the estimate of the Sommerfeld coefficient is proven to be close to the experimental value.

Dong, R.; Otsuki, J.; Savrasov, S. Y.

2013-04-01

275

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

276

The Friedel-Anderson Impurity with Orbital Degeneracy  

NASA Astrophysics Data System (ADS)

A recently developed compact solution for the non-degenerate Friedel-Anderson impurity is extended to impurities with orbital degeneracy. The singlet ground state is investigated for two and three orbits (corresponding to four and six d-states). The ground state energy and the multi-d-state occupations are calculated. The magnetic moment (above the Kondo temperature) is obtained in different regions of the parameter space of Vsd (s-d-hopping matrix element), Ed (d-state energy), U and Ux (Coulomb and exchange energies). The average d-state occupation can be adjusted to about one, two or three d-electrons. A comparison between different orbital degeneracy but the same d-state occupation is performed. The role of the Coulomb and the exchange interaction in the magnetic and singlet states is analyzed. The challenges for the treatment of a real d-impurity with five d-orbits is discussed.

Zhang, Liye; Bergmann, Gerd

2008-03-01

277

Adult versus Pediatric Neuroblastoma: The M.D. Anderson Cancer Center Experience.  

PubMed

Background. Staging and treatment of adult neuroblastoma has yet to be formalized. We sought to determine the utility of the pediatric classification system in adults and determine the efficacy of different treatment modalities. Methods. Medical records of 118 adults (patients >17 years old) and 112 pediatric patients (ages 2-17), who were treated for neuroblastoma at M.D. Anderson Cancer Center from January 1994 to September 2012, were reviewed. International neuroblastoma risk group (INRG) variables were abstracted. The primary outcome of interest was actuarial progression-free survival. Results. Median age of pediatric patients was 5 years (range 3-16) and 47 years (range 18-82) for adult patients. There were no differences in PFS or OS between stage-matched risk categories between pediatric and adult patients (L1-P = 0.40, L2-P = 0.54, and M-P = 0.73). In the treatment of L1 disease, median PFS for adults treated with surgery and radiation was 11.1 months compared with single modality local treatment ± chemotherapy (6.4 and 5.1 months, resp.; P = 0.07). Median PFS in L2 adult patients was 5.2 months with local therapy and 4 months with the addition of chemotherapy (P = 0.23). Conclusions. Adult and pediatric patients with neuroblastoma achieve similar survival outcomes. INRG classification should be employed to stratify adult neuroblastoma patients and help select treatment. PMID:25024639

Conter, Henry J; Gopalakrishnan, Vancheswaran; Ravi, Vinod; Ater, Joann L; Patel, Shreyaskumar; Araujo, Dejka M

2014-01-01

278

Adult versus Pediatric Neuroblastoma: The M.D. Anderson Cancer Center Experience  

PubMed Central

Background. Staging and treatment of adult neuroblastoma has yet to be formalized. We sought to determine the utility of the pediatric classification system in adults and determine the efficacy of different treatment modalities. Methods. Medical records of 118 adults (patients >17 years old) and 112 pediatric patients (ages 2–17), who were treated for neuroblastoma at M.D. Anderson Cancer Center from January 1994 to September 2012, were reviewed. International neuroblastoma risk group (INRG) variables were abstracted. The primary outcome of interest was actuarial progression-free survival. Results. Median age of pediatric patients was 5 years (range 3–16) and 47 years (range 18–82) for adult patients. There were no differences in PFS or OS between stage-matched risk categories between pediatric and adult patients (L1-P = 0.40, L2-P = 0.54, and M-P = 0.73). In the treatment of L1 disease, median PFS for adults treated with surgery and radiation was 11.1 months compared with single modality local treatment ± chemotherapy (6.4 and 5.1 months, resp.; P = 0.07). Median PFS in L2 adult patients was 5.2 months with local therapy and 4 months with the addition of chemotherapy (P = 0.23). Conclusions. Adult and pediatric patients with neuroblastoma achieve similar survival outcomes. INRG classification should be employed to stratify adult neuroblastoma patients and help select treatment.

Conter, Henry J.; Ravi, Vinod; Ater, Joann L.; Araujo, Dejka M.

2014-01-01

279

Ab initio study of local d-d excitations in bulk CoO, at the CoO(100) surface, and in octahedral Co2+ complexes  

Microsoft Academic Search

Quantum chemical ab initio calculations are presented for the lowest d-d excitation energies of Co2+ ions in bulk CoO, at the CoO(100) surface and, for comparison, in CoF2, in [Co(NH3)6]2+ complexes, and for Co2+ impurity ions in LiF. Different cluster models have been used for describing the octahedral or distorted octahedral surrounding of the Co2+ ions: A pure point-charge model,

Shouheng Shi; Volker Staemmler

1995-01-01

280

Excite Assistant  

NSDL National Science Digital Library

Just when the concept of "push" technology seems like yesterday's news, Excite, Inc. produces a handy little program, the Excite Assistant, that pushes data to you without being pushy. The Excite Assistant provides you with instant access to various types of up-to-date information such as the weather for your area, the broadcast TV shows on at the moment, updated stock quotes, your horoscope, and more. The information is summarized within the Assistant's window, but when an item requires expansion, your browser is launched. By far the most useful aspect of this program is the mail notification feature. If you use Excite's Web-based mail service, the Excite Assistant, if active, will play a sound and it's icon will blink when new mail arrives. The Assistant will display the subject line and who the mail is from; clicking on the new mail loads it in your browser. Excite Assistant runs on Win95/98/NT and is free but does display small ads.

281

MD Anderson study finds fetal exposure to radiation increases risk of testicular cancer  

Cancer.gov

Male fetuses of mothers that are exposed to radiation during early pregnancy may have an increased chance of developing testicular cancer, according to a study in mice at The University of Texas MD Anderson Cancer Center.

282

M.D. Anderson scientists identify a specialized regulatory T cell that stifles antibody production centers:  

Cancer.gov

A regulatory T cell that expresses three specific genes shuts down the mass production of antibodies launched by the immune system to attack invaders, a team led by scientists at The University of Texas MD Anderson Cancer Center reported...

283

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.

284

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.

285

MD Anderson researchers find that drug combination acts against aggressive chronic lymphocytic leukemia  

Cancer.gov

A two-prong approach combining ibrutinib and rituximab (Rituxin) to treat aggressive chronic lymphocytic leukemia (CLL) produced responses with minor side effects in a Phase 2 clinical trial at The University of Texas MD Anderson Cancer Center.

286

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

Federal Register 2010, 2011, 2012, 2013

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

2010-06-16

287

A new dataset of Wood Anderson magnitude from the Trieste (Italy) seismic station  

NASA Astrophysics Data System (ADS)

The standard torsion Wood Anderson (WA) seismograph owes its fame to the fact that historically it has been used for the definition of the magnitude of an earthquake (Richter, 1935). With the progress of the technology, digital broadband (BB) seismographs replaced it. However, for historical consistency and homogeneity with the old seismic catalogues, it is still important continuing to compute the so called Wood Anderson magnitude. In order to evaluate WA magnitude, the synthetic seismograms WA equivalent are simulated convolving the waveforms recorded by a BB instrument with a suitable transfer function. The value of static magnification that should be applied in order to simulate correctly the WA instrument is debated. The original WA instrument in Trieste operated from 1971 to 1992 and the WA magnitude (MAW) estimates were regularly reported in the seismic station bulletins. The calculation of the local magnitude was performed following the Richter's formula (Richter, 1935), using the table of corrections factor unmodified from those calibrated for California and without station correction applied (Finetti, 1972). However, the WA amplitudes were computed as vector sum rather than arithmetic average of the horizontal components, resulting in a systematic overestimation of approximately 0.25, depending on the azimuth. In this work, we have retrieved the E-W and N-S components of the original recordings and re-computed MAW according to the original Richter (1935) formula. In 1992, the WA recording were stopped, due to the long time required for the daily development of the photographic paper, the costs of the photographic paper and the progress of the technology. After a decade of interruption, the WA was recovered and modernized by replacing the recording on photographic paper with an electronic device and it continues presently to record earthquakes. The E-W and N-S components records were memorized, but not published till now. Since 2004, next to the WA (few decimeters apart), a Guralp 40-T BB seismometer was installed, with a proper period extended to 60 s. Aim of the present work is twofold: from one side to recover the whole data set of MAW values recorded from 1971 until now, with the correct estimate of magnitude, and from the other side to verify the WA static magnification, comparing the real WA data with the ones simulated from broadband seismometer recordings.

Sandron, Denis; Gentile, G. Francesco; Gentili, Stefania; Rebez, Alessandro; Santulin, Marco; Slejko, Dario

2014-05-01

288

Spectroscopy of Localized States in Zinc  

NASA Astrophysics Data System (ADS)

Strong exciton localization involving coupling to the lattice is observed in a II-VI compound semiconductor. The large Stokes shift of the photoluminescence (> 100meV) and a rapid spectral change from the blue to the green region within a narrow temperature (< 20K) range together with broadening under resonant excitation are observed spectroscopically in ZnSe _{1-x}Te_{x } alloys. These observations cannot be explained in the framework of Mott-Anderson localization which has been applied successfully to the majority of observations in weakly disordered bulk semiconductors and superlattices. An extrinsic self-trapping model is successfully employed to explain our experimental results. These experimental results support the coexistence of free and strongly localized states separated by an energy barrier between them, features which are characteristic of the latter model where local lattice relaxation is included. ZnSe/Zn_{1-x}Mn _{x}Se multiple quantum wells with delta-doping of ZnTe in the middle of the ZnSe quantum wells are used to discover microscopic details of such localization under circumstances of a high degree of spatial control in the distribution of Te isoelectronic centers in the realm of a 2D limit. Steady state spectra show that the absorption largely depends on the quantum well contribution while the emission is due to the strong capture of carriers, specifically photoexcited holes, to Te trapping sites which bind a hole in the spatial scale of one lattice constant. The decay time of luminescence changes dramatically from approximately 200psec for the undoped multiple quantum wells to several nanoseconds for the delta-doped structures, reflecting the reduction in the overlap of the electron and hole wave -functions. Energy transfer mechanisms between strongly coupled trapping centers are also studied in these structures with picosecond time resolved spectroscopy. Experimental results show that tunneling process is dominant at low temperatures but is overcome by thermal activation at higher temperatures (T > 70K).

Lee, Donghan

289

Conductance noise in interacting Anderson insulators driven far from equilibrium  

NASA Astrophysics Data System (ADS)

The combination of strong disorder and many-body interactions in Anderson insulators leads to a variety of intriguing nonequilibrium transport phenomena. These include slow relaxation and a variety of memory effects characteristic of glasses. Here we show that when such systems are driven with sufficiently high current and in a liquid-helium bath, a peculiar type of conductance noise can be observed. This noise appears in the conductance versus time traces as downward-going spikes. The characteristic features of the spikes (such as typical width) and the threshold current at which they appear are controlled by the sample parameters. We show that this phenomenon is peculiar to hopping transport and does not exist in the diffusive regime. Observation of conductance spikes hinges also on the sample being in direct contact with the normal phase of liquid helium; when this is not the case, the noise exhibits the usual 1/f characteristics independent of the current drive. A model based on the percolative nature of hopping conductance explains why the onset of the effect is controlled by the current density. It also predicts the dependence on disorder as confirmed by our experiments. To account for the role of the bath, the hopping transport model is augmented by a heuristic assumption involving nucleation of cavities in the liquid helium in which the sample is immersed. The suggested scenario is analogous to the way high-energy particles are detected in a Glaser’s bubble chamber.

Orlyanchik, V.; Ovadyahu, Z.

2005-07-01

290

Anderson–Fabry disease: Clinical manifestations of disease in female heterozygotes  

Microsoft Academic Search

Anderson–Fabry disease is a rare, X-chromosomal lipid storage disorder caused by a deficiency of lysosomal a-galactosidase A. Clinical manifestations of Anderson–Fabry disease include excruciating pain in the extremities (acroparaesthesia), skin vessel ectasia (angiokeratoma), corneal and lenticular opacity, cardiovascular disease, stroke and renal failure, only renal failure being a frequent cause of death. Heterozygote female carriers have often been reported as

C. Whybra; Chr. Kampmann; I. Willers; J. Davies; B. Winchester; J. Kriegsmann; K. Brühl; A. Gal; S. Bunge; M. Beck

2001-01-01

291

Results of a Nationwide Screening for Anderson-Fabry Disease among Dialysis Patients  

Microsoft Academic Search

Anderson-Fabry disease is possibly underdiagnosed in patients with end-stage renal disease. Nationwide screening was therefore undertaken for Anderson-Fabry disease among dialysis patients in Austria. Screening for -galactosidase A (AGAL) deficiency was performed by a blood spot test. In patients with a positive screening test, AGAL activity in leukocytes was deter- mined. Individuals with decreased leukocyte AGAL activity were subjected to

PETER KOTANKO; REINHARD KRAMAR; DANIJELA DEVRNJA; EDUARD PASCHKE; TILL VOIGTLANDER; MARTIN AUINGER; KLAUS DEMMELBAUER; MATTHIAS LORENZ; ANNA-CHRISTINE HAUSER; HANS-JORG KOFLER; KARL LHOTTA; ULRICH NEYER; WOLFGANG PRONAI; MANFRED WALLNER; CLEMENS WIESER; MARTIN WIESHOLZER; HERBERT ZODL; MANUELA FODINGER; GERE SUNDER-PLASSMANN; Krankenhaus Wels; Krankenhaus Lainz; Landeskrankenhaus Salzburg; Landeskrankenhaus Feldkirch; Landeskrankenhaus Klagenfurt

2004-01-01

292

Molecular excitation energies to high-lying bound states from time-dependent density-functional response theory: Characterization and correction of the time-dependent local density approximation ionization threshold  

NASA Astrophysics Data System (ADS)

This paper presents an evaluation of the performance of time-dependent density-functional response theory (TD-DFRT) for the calculation of high-lying bound electronic excitation energies of molecules. TD-DFRT excitation energies are reported for a large number of states for each of four molecules: N2, CO, CH2O, and C2H4. In contrast to the good results obtained for low-lying states within the time-dependent local density approximation (TDLDA), there is a marked deterioration of the results for high-lying bound states. This is manifested as a collapse of the states above the TDLDA ionization threshold, which is at -?HOMOLDA (the negative of the highest occupied molecular orbital energy in the LDA). The -?HOMOLDA is much lower than the true ionization potential because the LDA exchange-correlation potential has the wrong asymptotic behavior. For this reason, the excitation energies were also calculated using the asymptotically correct potential of van Leeuwen and Baerends (LB94) in the self-consistent field step. This was found to correct the collapse of the high-lying states that was observed with the LDA. Nevertheless, further improvement of the functional is desirable. For low-lying states the asymptotic behavior of the exchange-correlation potential is not critical and the LDA potential does remarkably well. We propose criteria delineating for which states the TDLDA can be expected to be used without serious impact from the incorrect asymptotic behavior of the LDA potential.

Casida, Mark E.; Jamorski, Christine; Casida, Kim C.; Salahub, Dennis R.

1998-03-01

293

Transition-state spectroscopy of the photoinduced Ca + CH3F reaction. 3. Reaction following the local excitation to Ca(4s3d 1D).  

PubMed

The Ca* + CH3F --> CaF* + CH3 reaction was studied both experimentally and theoretically. The reaction was photoinduced in Ca...CH3F complexes, which were illuminated by a tunable laser in the range 18 000-24 000 cm-1. The absorption band that leads to the reaction extends between 19 000 and 23 000 cm-1. It is formed of three broad overlapping structures corresponding to the excitation of different electronic states of the complex. The two structures of lowest energy were considered in detail. They are associated with two series of respectively 2 and 3 molecular states correlating to Ca(4s3d 1D) + CH3F at infinite separation between Ca and CH3F. The assignment of these structures to specific electronic transitions of the complex stemmed from theoretical calculations where the Ca...CH3F complex is described by a linear Ca-F-C backbone. 2D potential energy surfaces were calculated by associating a pseudopotential description of the [Ca2+] and [F7+] cores, a core polarization operator on calcium, an extensive Gaussian basis, and a treatment of the electronic problem at the CI-MRCI level. All the excited levels correlating to the 4s2 1S, 4s3d 1D, and 4s4p 1P levels of Ca in the Ca + CH3F channel were documented in a calculation that explored the rearrangement channels where either Ca + CH3F or CaF + CH3 are formed. Then, wavepacket calculations on the 2D-PES's allowed one to simulate the absorption spectrum of the complex, in an approximation where the various electronic states of the complex are not coupled together. The assignment above stemmed from this. The second outcome of the calculation was that whatever the excited level of the complex that is considered, the reaction has to proceed through energy barriers. The electronic excitation of the complex on the red side of the absorption band does not seem to deposit enough energy in the system to overcome these barriers (even the lowest one) or to stimulate tunneling reactions. An alternative reaction mechanism involving a transfer to triplet PES's is proposed. PMID:18232672

Gloaguen, E; Sanz Sanz, C; Collier, M; Gaveau, M-A; Soep, B; Roncero, O; Mestdagh, J-M

2008-02-21

294

Ab initio study of local d-d excitations in bulk CoO, at the CoO(100) surface, and in octahedral Co2+ complexes  

NASA Astrophysics Data System (ADS)

Quantum chemical ab initio calculations are presented for the lowest d-d excitation energies of Co2+ ions in bulk CoO, at the CoO(100) surface and, for comparison, in CoF2, in [Co(NH3)6]2+ complexes, and for Co2+ impurity ions in LiF. Different cluster models have been used for describing the octahedral or distorted octahedral surrounding of the Co2+ ions: A pure point-charge model, a CoO10-6 cluster (CoO8-5 at the surface) embedded in a point-charge (Madelung) field, and a CoO10-6 cluster surrounded by 18 effective core potentials in the next positive coordination shell and embedded in the point-charge field. The calculations for the ground state and the lowest excited states have been performed at the complete active space self-consistent field, valence configuration interaction, and multiconfiguration coupled-electron pair approach levels. The best results for the lowest excitation energies for bulk CoO are 0.80 eV (4T2g) and 1.71 eV (4A2g) which is slightly lower than experimental data derived from optical and electron-energy-loss (EEL) spectra. At the CoO(100) surface, the threefold spatial degenerate 4T1g ground state of bulk CoO is split by about 60 meV into a lower 4A2 and a higher 4E component. The same small splitting has been observed experimentally in high-resolution EEL spectra as a low-energy shoulder of the first Fuchs-Kliewer surface phonon. The splitting of the first excited 4T2g state of CoO at the CoO(100) surface is ~0.4 eV and gives rise to a surface state at 0.35 eV (experimentally at 0.45 eV).

Shi, Shouheng; Staemmler, Volker

1995-10-01

295

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

296

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

297

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

298

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

299

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

300

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

301

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

302

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, Stephen R.; Sorey, Michael L.; Counce, Dale; Colvard, Elizabeth M.

2000-01-01

303

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

304

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

305

Experimental observation of the Anderson metal-insulator transition with atomic matter waves.  

PubMed

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. PMID:19113725

Chabé, Julien; Lemarié, Gabriel; Grémaud, Benoît; Delande, Dominique; Szriftgiser, Pascal; Garreau, Jean Claude

2008-12-19

306

Gutzwiller Method for an Extended Periodic Anderson Model with the c--f Coulomb Interaction  

NASA Astrophysics Data System (ADS)

We study an extended periodic Anderson model with the Coulomb interaction Uc\\aku f between conduction and f electrons by the Gutzwiller method. The crossovers between the Kondo, intermediate-valence, and almost empty f-electron regimes become sharper with Uc\\aku f, and for a sufficiently large Uc\\aku f, become first-order phase transitions. In the Kondo regime, a large enhancement in the effective mass occurs as in the ordinary periodic Anderson model without Uc\\aku f. In addition, we find that a large mass enhancement also occurs in the intermediate-valence regime by the effect of Uc\\aku f.

Kubo, Katsunori

2011-11-01

307

Mass enhancement in an extended periodic Anderson model with valence fluctuations  

NASA Astrophysics Data System (ADS)

We study the mass enhancement in an extended periodic Anderson model with the Coulomb interaction Ucf between conduction and f-electrons by the Gutzwiller method. In the Kondo regime, where the number of f electrons nf per site is almost one, the mass enhancement factor becomes large as in the ordinary periodic Anderson model without Ucf. In the intermediate-valence regime, we find that the mass enhancement factor becomes large for a large Ucf. As a result, the effective mass can vary nonmonotonically as a function of nf, which may be relevant to the experimental observations of CeCu2Si2 under pressure.

Kubo, Katsunori

2012-12-01

308

Density Matrix Renormalization Group Study of the One-Dimensional Anderson Lattice  

NASA Astrophysics Data System (ADS)

We study the ground state and low energy excitations of the one-dimensional Anderson lattice using the density matrix renormalization group technique. We first look at the half-filled case, with the purpose of modeling Kondo insulators. We calculate the charge gap, spin gap and quasiparticle gap as a function of the repulsive interaction U using open boundary conditions for lattices as large as 24 sites. We find that the charge gap is larger than the spin gap for all U for both the symmetric and asymmetric cases. RKKY interactions are evident in the f-spin-f-spin correlation functions at large U in the symmetric case, but are suppressed in the asymmetric case as the f-level approaches the Fermi energy. This suppression can also be seen in the staggered susceptibility chi(q=2k _{f}), and it is consistent with neutron scattering measurements of chi(q) in CeNiSn. We investigate the effect of a small dispersion in the f-band. We find that in the strong coupling limit the quasiparticle gap remains almost unaffected by the hopping of the f-electrons. However, the spin gap is strongly suppressed. We also consider the system away from half-filling (metallic case). We map out the phase diagram by studying the ground state magnetization as a function of band filling using the density matrix renormalization group technique. For strong coupling, we find that the quarter-filled system has an S=0 ground state with strong antiferromagnetic correlations. As additional electrons are added, we find first a ferromagnetic phase, as reported by Moller and Wolfle, and then a phase in which the ground state has total spin S = 0. Within this S = 0 phase, we find RKKY oscillations in the spin-spin correlation functions. In addition, we study the case of a magnetic impurity in a semiconducting host. We compare the behavior of this system with the case of an impurity in a metal.

Guerrero, Mariana

1995-01-01

309

Multifractality and quantum-to-classical crossover in the Coulomb anomaly at the Mott-Anderson metal-insulator transition  

NASA Astrophysics Data System (ADS)

We study the interaction-driven localization transition, which a recent experiment (Richardella et al 2010 Science 327 665) in Ga1-xMnxAs has shown to come along with the multifractal behavior of the local density of states (LDoS) and the intriguing persistence of critical correlations close to the Fermi level. We show that the bulk of these phenomena can be understood within a Hartree-Fock (HF) treatment of disordered, Coulomb-interacting spinless fermions. A scaling analysis of the LDoS correlation demonstrates multifractality with the correlation dimension d2 ? 1.57, which is significantly larger than at a non-interacting Anderson transition and is compatible with the experimental value dexp2 = 1.8 ± 0.3. At the interaction-driven transition, the states at the Fermi level become critical, while the bulk of the spectrum remains delocalized up to substantially stronger interactions. The mobility edge stays close to the Fermi energy in a wide range of disorder strength, as the interaction strength is further increased. The localization transition is concomitant with the quantum-to-classical crossover in the shape of the pseudo-gap in the tunneling density of states, and with the proliferation of metastable HF solutions that suggest the onset of a glassy regime with poor screening properties.

Amini, M.; Kravtsov, V. E.; Müller, M.

2014-01-01

310

Localization of light in a disordered medium  

Microsoft Academic Search

Among the unusual transport properties predicted for disordered materials is the Anderson localization phenomenon. This is a disorder-induced phase transition in the electron-transport behaviour from the classical diffusion regime, in which the well-known Ohm's law holds, to a localized state in which the material behaves as an insulator. The effect finds its origin in the interference of electrons that have

Diederik S. Wiersma; Paolo Bartolini; Ad Lagendijk; Roberto Righini

1997-01-01

311

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

2008-01-25

312

Saturated excitation microscopy with optimized excitation modulation.  

PubMed

Saturated excitation (SAX) microscopy utilizes the nonlinear relation between fluorescence emission and excitation under saturated excitation to improve the spatial resolution of confocal microscopy. In this study, we theoretically and experimentally investigate the saturation of fluorescence excitation under modulated excitation to optimize the excitation conditions for SAX microscopy. Calculation of the relationships between fluorescence and excitation intensity with different modulation frequencies reveals that the lifetime of the triplet state of the fluorescent probe strongly affects the strength of the demodulated fluorescence signals. We also find that photobleaching shows little dependence on the modulation frequency. These investigations allow us to determine the optimum excitation conditions, that is, the conditions providing sufficient fluorescence saturation without strong photobleaching. For a sample stained with ATTO Rho6G phalloidin, we estimate the optimal excitation conditions, which are produced with 50 kHz excitation modulation and a 50 ?sec pixel dwell time, and successfully perform three-dimensional imaging with sub-diffraction resolution. PMID:24488765

Yonemaru, Yasuo; Yamanaka, Masahito; Smith, Nicholas I; Kawata, Satoshi; Fujita, Katsumasa

2014-03-17

313

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

314

Nonperturbative spectral-density function for the Anderson model at arbitrary temperatures  

NASA Technical Reports Server (NTRS)

Using a nonperturbative self-energy solution for the nondegenerate Anderson model, the temperature-dependent spectral-density function is calculated in the symmetric limit. The function is found to give reliable results for all values of the parameter u and inverse temperature beta.

Neal, Henry L.

1991-01-01

315

MD Anderson scientists discover marker to identify, attack breast cancer stem cells  

Cancer.gov

Breast cancer stem cells wear a cell surface protein that is part nametag and part bull’s eye, identifying them as potent tumor-generating cells and flagging their vulnerability to a drug, researchers at The University of Texas MD Anderson Cancer Center report online in Journal of Clinical Investigation.

316

M.D. Anderson study finds previously unconnected molecular networks conspire to promote cancer:  

Cancer.gov

An inflammation-promoting protein triggers deactivation of a tumor-suppressor that usually blocks cancer formation via the NOTCH signaling pathway, a team of researchers led by scientists at The University of Texas M.D. Anderson Cancer Center reports today in Molecular Cell.

317

Dystopian Visions of Global Capitalism: Philip Reeve's "Mortal Engines" and M.T Anderson's "Feed"  

ERIC Educational Resources Information Center

This article examines Philip Reeve's novel for children, "Mortal Engines", and M.T. Anderson's young adult novel, "Feed", by assessing these dystopias as prototypical texts of what Ulrich Beck calls risk society. Through their visions of a fictional future, the two narratives explore the hazards created by contemporary techno-economic progress,…

Bullen, Elizabeth; Parsons, Elizabeth

2007-01-01

318

Conversations with Three Highly Productive Educational Psychologists: Richard Anderson, Richard Mayer, and Michael Pressley  

Microsoft Academic Search

This article seeks to answer the question, What factors characterize highly productive educational psychologists? Using qualitative research methods, we identified three top scholars in educational psychology—Richard Anderson, Richard Mayer, and Michael Pressley—and examined factors that influence their work. Although each scholar had a distinctive trademark characteristic, they had much in common. Each had an impressive lineage, gravitated to centers of

Kenneth A. Kiewra; John W. Creswell

2000-01-01

319

MD Anderson study finds gene therapy kills breast cancer stem cells, boosts chemotherapy:  

Cancer.gov

Gene therapy delivered directly to a particularly stubborn type of breast cancer cell causes the cells to self-destruct, lowers the chance of recurrence and helps increase the effectiveness of some types of chemotherapy, researchers at The University of Texas MD Anderson Cancer Center reported in the Sept. 13 edition of Cancer Cell.

320

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.

321

MD Anderson study finds tamoxifen causes significant side effects in male breast cancer patients:  

Cancer.gov

About half of male breast cancer patients who take the drug tamoxifen to prevent their disease from returning report side effects such as weight gain and sexual dysfunction, which prompts more than 20 percent of them to discontinue treatment, according to researchers at The University of Texas MD Anderson Cancer Center.

322

Absence of diffusion in the Anderson tight binding model for large disorder or low energy  

Microsoft Academic Search

We prove that the Green's function of the Anderson tight binding Hamiltonian decays exponentially fast at long distances on Zv, with probability 1. We must assume that either the disorder is large or the energy is sufficiently low. Our proof is based on perturbation theory about an infinite sequence of block Hamiltonians and is related to KAM methods.

Jürg Fröhlich; Thomas Spencer

1983-01-01

323

MD Anderson study finds that AML patients have high response rate with Vorinostat added to treatment  

Cancer.gov

Adding a drug that activates genes to frontline combination therapy for acute myeloid leukemia resulted in an 85 percent remission rate after initial treatment, researchers at The University of Texas MD Anderson Cancer Center reported at the 53rd Annual Meeting of the American Society of Hematology.

324

MD Anderson study finds everolimus prolongs progression-free survival for patients with neuroendocrine tumors:  

Cancer.gov

Combination treatment with everolimus, an inhibitor of the mammalian target rapamycin (mTOR), and octreotide has shown to improve progression-free survival for patients with advanced neuroendocrine tumors and a history of carcinoid syndrome, according to researchers at The University of Texas MD Anderson Cancer Center.

325

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.

326

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

327

Study led by MD Anderson scientists identifies prostate cancer stem cells among low-PSA cells  

Cancer.gov

Prostate cancer cells that defy treatment and display heightened tumor-generating capacity can be identified by levels of prostate specific antigen (PSA) expressed in the tumor cells, a research team led by scientists at The University of Texas MD Anderson Cancer Center reports in the May 3 edition of Cell Stem Cell.

328

UT MD Anderson study finds metabolic protein plays unexpected role in tumor cell formation and growth:  

Cancer.gov

The embryonic enzyme pyruvate kinase M2 (PKM2) has a well-established role in metabolism and is highly expressed in human cancers. Now, a team led by researchers at The University of Texas MD Anderson Cancer Center reports in advance online publication of the journal Nature that PKM2 has important non-metabolic functions in cancer formation.

329

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.

330

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

331

MD Anderson study identifies novel therapeutic targets for small cell lung cancer  

Cancer.gov

Newly discovered molecular differences between small cell lung cancer and non-small cell lung cancer have revealed PARP1 and EZH2 as potential therapeutic targets for patients with small cell lung cancer, according to the results of a University of Texas MD Anderson study published in Cancer Discovery, a journal of the American Association for Cancer Research.

332

MD Anderson study finds ovarian cancer patients survive longer with BRCA2 mutated in tumors:  

Cancer.gov

Women with high-grade ovarian cancer live longer and respond better to platinum-based chemotherapy when their tumors have BRCA2 genetic mutations, researchers at The University of Texas MD Anderson Cancer Center and the Institute for Systems Biology report in the Oct. 12 issue of the Journal of the American Medical Association.

333

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.

334

Electron spin polarization transfer to the charge-separated state from locally excited triplet configuration: theory and its application to characterization of geometry and electronic coupling in the electron donor-acceptor system.  

PubMed

We present a theoretical model of analysis of the time-resolved electron paramagnetic resonance (TREPR) spectrum of the charge-separated (CS) state generated by the photoinduced electron transfer (ET) reaction via the locally excited triplet state in an electron donor-acceptor (D-A) system with a fixed molecular orientation. We show, by the stochastic-Liouville equation, that chemically induced dynamic electron polarization (CIDEP) of the triplet mechanism is explained by lack of transfer of quantum coherence terms in the primary triplet spin state, resulting in net emissive or absorptive electron spin polarization (ESP) which is dependent on anisotropy of the singlet-triplet intersystem crossing in the precursor excited state. This disappearance of the coherence is clearly shown to occur when the photoinduced ET rate is smaller than the angular frequency of the Zeeman splitting: the transferred coherence terms are averaged to be zero due to effective quantum oscillations during the time that the chemical reaction proceeds. The above theory has been applied to elucidate the molecular geometries and spin-spin exchange interactions (2J) of the CS states for both folded and extended conformers by computer simulations of TREPR spectra of the zinc porphyrin-fullerene dyad (ZnP-C(60)) bridged by diphenyldisilane. On the extended conformation, the electronic coupling is estimated from the 2J value. It has been revealed that the coupling term is smaller than the reported electronic interactions of the porphyrin-C(60) systems bridged by diphenylamide spacers. The difference in the electronic couplings has been explained by the difference in the LUMO levels of the bridge moieties that mediate the superexchange coupling for the long-range ET reaction. PMID:20509645

Kobori, Yasuhiro; Fuki, Masaaki; Murai, Hisao

2010-11-18

335

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

336

Nonlinear excitations in lattices  

NASA Astrophysics Data System (ADS)

We analyze some of the properties of nonlinear excitations occurring in lattices such as polarons, bipolarons or discrete breathers (DBs). While polarons and bipolarons are the result of the self-trapping of one or two electronic carriers by the lattice distortion they generate, DBs occur in networks of identical non-harmonic oscillators as exact solutions to the equations of motion that are both time-periodic and spatially localized. In certain limits, these excitations may be described by a common class of models: the Discrete Nonlinear Schrodinger Equation and its generalizations. We first use an exact perturbative expansion to derive the bipolaronic phase diagram of the 1D adiabatic Holstein-Hubbard model (HH) in the strong coupling limit. In the second part of the thesis we study DBs on d-dimensional cubic lattices with arbitrary power nonlinearity. We compare the exact results to an exponential ansatz approach and to the solution to the Single Nonlinear Impurity (SNI) model. We show that DB excitation thresholds can be evaluated explicitly in the limit of high nonlinearity, and we prove a conjecture by Bustamante and Molina [PRB 62, 15287 (2000)] that the limiting value of the SNI bound state energy is universal as the nonlinearity tends to infinity.

Zhou, Jun

337

Localization, Localization, Localization  

NASA Technical Reports Server (NTRS)

Localization of the two Mars Exploration Rovers involved three independent approaches to place the landers with respect to the surface of Mars and to refine the location of those points on the surface with the Mars control net: 1) Track the spacecraft through entry, descent, and landing, then refine the final roll stop position by radio tracking and comparison to images taken during descent; 2) Locate features on the horizon imaged by the two rovers and compare them to the MOC and THEMIS VIS images, and the DIMES images on the two MER landers; and 3) 'Check' and refine locations by acquisition of MOC 1.5 meter and 50 cm/pixel images.

Parker, T.; Malin, M.; Golombek, M.; Duxbury, T.; Johnson, A.; Guinn, J.; McElrath, T.; Kirk, R.; Archinal, B.; Soderblom, L.

2004-01-01

338

Success and failure of the Friedel-Anderson resonance model for magnetic impurities: 3{ital d} impurities on the surface of Au  

SciTech Connect

The magnetic character of 3{ital d} atoms on the surface of Au is investigated using the method of quantum interference (weak localization). We find that single atoms of V, Cr, Mn, Fe, and Co are magnetic on the surface of Au while single atoms of Sc and Ni are nonmagnetic. Single atoms of Ti are locally spin fluctuating. The magnetic dephasing due to the 3{ital d} impurities has two maxima, one for iron and a smaller one for chromium impurities and a minimum for manganese. This behavior can be qualitatively described within the Friedel-Anderson model although the experimental values are smaller by roughly a factor of 5 than our theoretical estimates within this model. {copyright} {ital 1996 The American Physical Society.}

Beckmann, H.; Bergmann, G. [Department of Physics, University of Southern California, Los Angeles, California 90089-0484 (United States)] [Department of Physics, University of Southern California, Los Angeles, California 90089-0484 (United States)

1996-07-01

339

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

340

Carrier excitation by atomic collisions at semiconductor surfaces  

NASA Astrophysics Data System (ADS)

We have furthered our understanding of the collisional excitation of carriers at semiconductor surfaces due to hyperthermal neutral-atom scattering, with additional experiments and analyses. We compare the excitation efficiency of Xe to Kr over a range of energies and angles for the InP(100) surface. We extract absolute collisional excitation probabilities using optical carrier excitation to determine carrier recombination rates. We compare excitations on InP(100) to InP(110). The results confirm, on a more quantitative basis, the concept of a rapid equilibration of electronic excitations to a transient local lattice excitation in the vicinity of the atomic impact.

Weiss, P. S.; Trevor, P. L.; Cardillo, M. J.

1988-11-01

341

The inducement of meaningful work: a response to Anderson and Weijer.  

PubMed

James A. Anderson and Charles Weijer take the wage payment model proposed by Neil Dickert and Christine Grady and extend the analogy of research participation to unskilled wage labor to include just working conditions. Although noble in its intentions, this moral extension generates unsavory outcomes. Most notably, Anderson and Weijer distinguish between two types of research subjects: occasional and professional. The latter, in this case, receives benefits beyond the moral minima in the form of "the right to meaningful work." The problem is that meaningful work can itself be a form of inducement, and consequently, may in fact increase the incidence of inducement contrary to the intentions of the wage payment model. PMID:16245007

McEachern, Terrence P

2005-01-01

342

Mott-Anderson transition in disordered charge-transfer model: Insights from typical medium theory  

NASA Astrophysics Data System (ADS)

The Mott-Anderson transition in the disordered charge-transfer model displays several new features in comparison to what is found in the disordered single-band Hubbard model, as recently demonstrated by large-scale computational (statistical dynamical mean-field theory) studies. Here we show that a much simpler typical medium theory approach (TMT-DMFT) to the same model is able to capture most qualitative and even quantitative aspects of the phase diagram, the emergence of an intermediate electronic Griffiths phase, and the critical behavior close to the metal-insulator transition. The conceptual and mathematical simplicity of the TMT-DMFT formulation thus makes it possible to gain useful new insight into the mechanism of the Mott-Anderson transition in these models.

Oliveira, W. S.; Aguiar, M. C. O.; Dobrosavljevi?, V.

2014-04-01

343

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

Federal Register 2010, 2011, 2012, 2013

...Docket No. FD 35700] Chessie Logistics Co., LLC--Acquisition and...Anderson & Son, Inc. Chessie Logistics Co., LLC (Chessie), a noncarrier...Erbacher, Legal Counsel, Chessie Logistics Co., LLC, 1001 Green Bay Rd., Unit 204,...

2012-12-06

344

Underscreened Kondo lattice model versus underscreened Anderson lattice model: Application to uranium compounds  

Microsoft Academic Search

We present here two theoretical models, the underscreened Kondo lattice (UKL) model and the underscreened Anderson lattice (UAL) model, which are appropriate models for a description of the coexistence of Kondo effect and ferromagnetic order experimentally observed in various uranium compounds. First we discuss a Kondo-ferromagnetic diagram (KFD), obtained in the framework of the UKL model with S=1 [N.B. Perkins,

B. Coqblin; J. R. Iglesias; N. B. Perkins; Acirete S. Da R. Simoes; Christopher Thomas

2009-01-01

345

Application of the S=1 underscreened Anderson lattice model to Kondo uranium and neptunium compounds  

Microsoft Academic Search

Magnetic properties of uranium and neptunium compounds showing the coexistence of the Kondo screening effect and ferromagnetic order are investigated within the Anderson lattice Hamiltonian with a two-fold degenerate f level in each site, corresponding to 5f2 electronic configuration with S=1 spins. A derivation of the Schrieffer-Wolff transformation is presented and the resulting Hamiltonian has an effective f-band term, in

Christopher Thomas; Acirete S. da Rosa Simões; J. R. Iglesias; C. Lacroix; N. B. Perkins; B. Coqblin

2011-01-01

346

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

347

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

SciTech Connect

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

Dorin, V.; Schlottmann, P. (Department of Physics and Center for Materials Research and Technology, Florida State University, Tallahassee, Florida 32306 (United States))

1993-05-15

348

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.

349

Many electron variational ground state of the two dimensional Anderson lattice  

SciTech Connect

A variational upper bound of the ground state energy of two dimensional finite Anderson lattices is determined as a function of lattice size (up to 16 x 16). Two different sets of many-electron basis vectors are used to determine the ground state for all values of the coulomb integral U. This variational scheme has been successfully tested for one dimensional models and should give good estimates in two dimensions.

Zhou, Y.; Bowen, S.P. [Argonne National Lab., IL (United States). Materials Science Div.; Mancini, J.D. [Fordham Univ., Bronx, NY (United States). Dept. of Physics

1991-02-01

350

The relativistic Burnett equations from a moment closure of the Anderson and Witting model equation  

NASA Astrophysics Data System (ADS)

The Burnett constitutive equations for the dynamic pressure, heat flux and pressure deviator of a relativistic gas are calculated from a moment closure of the Anderson and Witting model equation. The transport coefficients obtained are compared with those that follow by the use of the full Boltzmann equation. The comparison shows that all transport coefficients have the same behavior in the ultra-relativistic and in the relativistic regime up to ?= mc2/( kT)?0.5.

Samojeden, L. L.; Kremer, G. M.

2002-05-01

351

MD Anderson study finds qigong improves quality of life for breast cancer patients undergoing radiation therapy  

Cancer.gov

Researchers from The University of Texas MD Anderson Cancer Center have found qigong, an ancient mind-body practice, reduces depressive symptoms and improves quality of life in women undergoing radiotherapy for breast cancer. The study, published in the journal Cancer, is the first to examine qigong in patients actively receiving radiation therapy and includes a follow-up period to assess benefits over time.

352

Central nervous system involvement in Anderson-Fabry disease: a clinical and MRI retrospective study  

Microsoft Academic Search

Background: Anderson-Fabry disease (AFD) is an X-linked lysosomal storage disorder caused by deficiency of alpha-galactosidase A. Central nervous system (CNS) manifestations consist mainly of cerebrovascular events. Brain MRI results are often abnormal. Purpose: The aim of the study was to describe CNS involvement in a group of Italian patients with AFD. Methods: Clinical and brain MRI data of 43 patients

S Buechner; M Moretti; A P Burlina; G Cei; R Manara; R Ricci; R Mignani; R Parini; R Di Vito; G P Giordano; P Simonelli; G Siciliano; W Borsini

2008-01-01

353

Anderson-Fabry disease with cerebrovascular complications in two Italian families  

Microsoft Academic Search

.   We describe four patients with cerebrovascular complications from two unrelated Italian families with Anderson-Fabry disease.\\u000a Clinical examination, neuroimaging (MRI), biochemical and genetic analyses were carried out in all the patients. ?-Galactosidase\\u000a A activity was detected by fluorimetric assay and genetic analysis was performed by DNA sequencing. Family 1. A male patient presented recurrent strokes when he was 34 years

W. Borsini; G. Giuliacci; F. Torricelli; E. Pelo; F. Martinelli; M. R. Scordo

2002-01-01

354

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

NASA Astrophysics Data System (ADS)

Two isostructural compounds based on Anderson polyoxoanions, [Cu(phen)] 2[CrMo 6H 5O 24] ( 1) and [Cu(phen)] 2[AlMo 6H 5O 24] ( 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) Å 3, R1 = 0.0240, Z = 2 and GOF = 1.140 for 1, and in the monoclinic space group P2(1)/ n with a = 5.6641(3) Å, b = 21.3346(13) Å, c = 14.6909(9) Å, ? = 97.9120(10)°, V = 1758.37(18) Å 3, R1 = 0.0529, Z = 2 and GOF = 0.0994 for 2. Single crystal X-ray diffraction reveals that the compounds 1 and 2 are both built up of Anderson polyoxoanions and copper-phen complexes. The structural feature of 1 and 2 is that the Anderson polyoxoanions act as multidentate ligands linking copper-phen complex to form 1D chains. Compounds 1 and 2 not only represent new Anderson-type POM-supported transition metal organic-inorganic hybrid compounds with extend structure, but also verify the feasibility of constructing these compounds through hydrothermal methods.

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

2010-04-01

355

1/(N-1) expansion based on a perturbation theory in U of an SU(N) Anderson impurity  

NASA Astrophysics Data System (ADS)

We propose a new large-N scheme to an N-fold degenerate impurity Anderson model with a finite Coulomb interaction U [1,2]. This approach is different from the conventional theories, such as 1/N expansion and non-crossing approximation, which are based on a perturbation expansion in the hybridization strength V. Our expansion scheme uses a scaling that takes u=(N-1)U as an independent variable, and provides the Hartree-Fock (HF) approximation at zeroth order. Then, to leading order in 1/(N-1) it describes the Hartree-Fock random phase approximation (HF-RPA). The higher-order corrections describe systematically the fluctuations beyond the HF-RPA. We have calculated the renormalized parameters for the local Fermi liquid up to order 1/(N-1)^2, and found that the next-leading-order results agree closely with the exact NRG results at N=4, where the degeneracy is still not really large. This ensures the reliability of our approach for N >=4. We apply this approach to Kondo physics in quantum dots. [1] A.O., R. Sakano, and T. Fujii, PRB 84, 113301 (2011). [2] A.O., PRB 85, 155404 (2012).

Oguri, Akira; Sakano, Rui; Fujii, Tatsuya

2013-03-01

356

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

357

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

NASA Astrophysics Data System (ADS)

Studies of the goodness-of-fit test, which describes how well a model fits a set of observations with an assumed distribution, have long been the subject of statistical research. The selection of an appropriate probability distribution is generally based on goodness-of-fit tests. This test is an effective means of examining how well a sample data set agrees with an assumed probability distribution that represents its population. However, the empirical distribution function test gives equal weight to the differences between the empirical and theoretical distribution functions corresponding to all observations. The modified Anderson-Darling test, suggested by Ahmad et al. (1988), uses a weight function that emphasizes the tail deviations at the upper or lower tails. In this study, we derive new regression equation forms of the critical values for the modified Anderson-Darling test statistics considering the effect of unknown shape parameters. The regression equations are derived using simulation experiments for extreme value distributions such as the log-Gumbel, generalized Pareto, GEV, and generalized logistic models. In addition, power test and at-site frequency analyses are performed to evaluate the performance and to explain the applicability of the modified Anderson-Darling test.

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

2013-08-01

358

Local magnitude scale in Slovenia  

NASA Astrophysics Data System (ADS)

In the paper a calibration study of the local magnitude scale in Slovenia is presented. The Seismology and Geology Office of the Slovenian Environment Agency routinely reports the magnitudes MLV of the earthquakes recorded by the Slovenian seismic stations. The magnitudes are computed from the maximum vertical component of the ground velocity with the magnitude equation that was derived some thirty years ago by regression analysis of the magnitudes recorded by a Wood-Anderson seismograph in Trieste and a short period seismograph in Ljubljana. In the study the present single magnitude MLV equation is replaced by a general form of the Richter local magnitude MWA equation. The attenuation function and station-component corrections that compensate the local effects near seismic stations are determined from the synthetic Wood-Anderson seismograms of a large data set by iterative least-square method. The data set used consists of approximately 18 000 earthquakes during a period of 14 yr, each digitally recorded on up to 29 stations. The derived magnitude equation is used to make the final comparison between the new MWA magnitudes and the routinely calculated MLV magnitudes. The results show good overall accordance between both magnitude equations. The main advantage of the introduction of station-component corrections is the reduced uncertainty of the local magnitude that is assigned to a certain earthquake.

Bajc, J.; Zaplotnik, Ž.; Živ?i?, M.; ?arman, M.

2013-04-01

359

Resources available for nuclear power plant emergencies under the Price-Anderson Act and the Robert T. Stafford Disaster Relief and Emergency Assistance Act  

SciTech Connect

Through a series of TABLETOP exercises and other events that involved participation by State and Federal organizations, the need was identified for further explanation of financial and other related resources available to individuals and State and local governments in a major emergency at a nuclear power plant. A group with representatives from the Nuclear Regulatory commission, the Federal Emergency Management Agency, and the American Nuclear Insurers/Mutual Atomic Energy Liability Underwriters was established to work toward this end. This report is the result of that effort. This document is not meant to modify, undermine, or replace any other planning document (e.g., the Federal Radiological Emergency Response Plan or the Federal Response Plan). Its purpose is to clarify issues that have surfaced regarding resources available under the Price-Anderson and Stafford Acts.

Not Available

1992-07-01

360

Utilization of Live Localized Weather Information for Sustainable Agriculture  

Microsoft Academic Search

Authors: Jim Anderson VP, Global Network and Business Development WeatherBug® Professional Jeremy Usher Managing Director, Europe WeatherBug® Professional Localized, real-time weather information is vital for day-to-day agronomic management of all crops. The challenge for agriculture is twofold in that local and timely weather data is not often available for producers and farmers, and it is not integrated into decision-support tools

J. Anderson; J. Usher

2010-01-01

361

Disorder-induced localization in crystalline phase-change materials  

Microsoft Academic Search

Localization of charge carriers in crystalline solids has been the subject of numerous investigations over more than half a century. Materials that show a metal-insulator transition without a structural change are therefore of interest. Mechanisms leading to metal-insulator transition include electron correlation (Mott transition) or disorder (Anderson localization), but a clear distinction is difficult. Here we report on a metal-insulator

T. Siegrist; P. Jost; H. Volker; M. Woda; P. Merkelbach; C. Schlockermann; M. Wuttig

2011-01-01

362

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

USGS Publications Warehouse

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

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

1999-01-01

363

Anisotropic behavior of quantum transport in graphene superlattices: Coexistence of ballistic conduction with Anderson insulating regime  

NASA Astrophysics Data System (ADS)

We report on the possibility to generate highly anisotropic quantum conductivity in disordered graphene-based superlattices. Our quantum simulations, based on an efficient real-space implementation of the Kubo-Greenwood formula, show that in disordered graphene superlattices the strength of multiple scattering phenomena can strongly depend on the transport measurement geometry. This eventually yields the coexistence of a ballistic waveguide and a highly resistive channel (Anderson insulator) in the same two-dimensional platform, evidenced by a ?yy/?xx ratio varying over several orders of magnitude, and suggesting the possibility of building graphene electronic circuits based on the unique properties of chiral massless Dirac fermions in graphene.

Pedersen, Jesper Goor; Cummings, Aron W.; Roche, Stephan

2014-04-01

364

STS-118 Astronaut Williams and Expedition 15 Engineer Anderson Perform EVA  

NASA Technical Reports Server (NTRS)

As the construction continued on the International Space Station (ISS), STS-118 Astronaut Dave Williams, representing the Canadian Space Agency, participated in the fourth and final session of Extra Vehicular Activity (EVA). During the 5 hour space walk, Williams and Expedition 15 engineer Clay Anderson (out of frame) installed the External Wireless Instrumentation System Antenna, attached a stand for the shuttle robotic arm extension boom, and retrieved the two Materials International Space Station Experiments (MISSE) for return to Earth. MISSE collects information on how different materials weather in the environment of space.

2007-01-01

365

STS-89 Mission Specialist Michael Anderson is assisted with his flight suit in the white room  

NASA Technical Reports Server (NTRS)

STS-89 Mission Specialist Michael Anderson is assisted with his ascent and re-entry flight suit in the white room at Launch Pad 39A before entering Space Shuttle Endeavour for launch. The STS- 89 mission will be the eighth docking of the Space Shuttle with the Russian Space Station Mir. After docking, Mission Specialist Andrew Thomas, Ph.D., will transfer to the space station, succeeding David Wolf, M.D., who will return to Earth aboard Endeavour. Dr. Thomas will live and work on Mir until June. STS- 89 is scheduled for a Jan. 22 liftoff at 9:48 p.m.

1998-01-01

366

STS-107 Payload Commander Michael Anderson during TCDT M113 training activities  

NASA Technical Reports Server (NTRS)

KENNEDY SPACE CENTER, FLA. -- -- STS-107 Payload Commander Michael Anderson takes a break during training on the operation of an M113 armored personnel carrier during Terminal Countdown Demonstration Test activities, a standard part of launch preparations. STS-107 is a mission devoted to research and will include more than 80 experiments that will study Earth and space science, advanced technology development, and astronaut health and safety. Launch is planned for Jan. 16, 2003, between 10 a.m. and 2 p.m. EST aboard Space Shuttle Columbia.

2002-01-01

367

MD Anderson study finds depression and shortened telomeres increase bladder cancer mortality  

Cancer.gov

The combination of shortened telomeres, a biological marker of aging associated with cancer development, and elevated depression significantly impacted bladder cancer mortality, according to data presented at the 11th Annual AACR International Conference on Frontiers in Cancer Prevention Research. As part of an ongoing, large-scale epidemiologic study of bladder cancer, researchers from the MD Anderson Cancer Center in Houston collected clinical and mental health information on 464 patients with bladder cancer. They assessed patients' depression levels with the Center for Epidemiologic Studies Depression Scale.

368

Application of the S=1 underscreened Anderson lattice model to Kondo uranium and neptunium compounds  

Microsoft Academic Search

Magnetic properties of uranium and neptunium compounds showing the\\u000acoexistence of Kondo screening effect and ferromagnetic order are investigated\\u000awithin the Anderson lattice Hamiltonian with a two-fold degenerate $f$-level in\\u000aeach site, corresponding to $5f^2$ electronic configuration with $S=1$ spins. A\\u000aderivation of the Schrieffer-Wolff transformation is presented and the\\u000aresulting Hamiltonian has an effective $f$-band term, in addition to

Christopher Thomas; Acirete S. da Rosa Simões; J. R. Iglesias; C. Lacroix; N. B. Perkins; B. Coqblin

2010-01-01

369

Cardiac Anderson-Fabry disease: Lessons from a 25-year-follow up.  

PubMed

Sarcomeric hypertrophic cardiomyopathy (HCM) is the most common genetic cause of unexplained left ventricular hypertrophy and has no specific treatment. Anderson-Fabry disease (AFD) is rare and usually multisystemic, but occasionally expresses clinically as a predominantly cardiac phenotype mimicking HCM. We describe an illustrative case of a patient followed regularly for 25 years with a diagnosis of familial HCM and no identified sarcomeric mutations. Next-generation sequencing analysis identified a novel pathogenic mutation in the GLA gene, leading to a diagnosis of previously unknown multisystemic AFD, with consequent implications for the patient's treatment and prognosis and familial screening. PMID:24830310

Brito, Dulce; Miltenberger-Miltenyi, Gabriel; Moldovan, Oana; Navarro, Carmen; Madeira, Hugo Costa

2014-04-01

370

Dynamic susceptibility of the Anderson model: A quantum Monte Carlo study  

SciTech Connect

Using a highly accurate method of analytic continuation, we calculated the dynamic susceptibility and NMR relaxation rate 1/{ital T}{sub 1} of magnetic (Anderson or Kondo) impurities over the {ital entire} range {ital T}{much lt}{ital T}{sub {ital K}} to {ital T}{much gt}{ital T}{sub {ital K}}. We find that the susceptibility and NMR relaxation rate are universal functions when properly scaled and that the NMR relaxation rate is directly proportional to the universal Kondo resistivity.

Jarrell, M. (Department of Physics, University of Cincinnati, Cincinnati, Ohio (USA)); Gubernatis, J.E. (Theoretical Division, Los Alamos National Laboratory, Los Alamos, New Mexico (USA)); Silver, R.N. (Theoretical Division, Los Alamos National Laboratory, Los Alamos, New Mexico (USA) Manuel Lujan, Jr. Neutron Scattering Center, Los Alamos National Laboratory, Los Alamos, New Mexico (USA))

1991-09-01

371

Atmospheric optical turbulence measurements taken at Anderson Mesa, Flagstaff, Arizona between 13-19 November 1989  

NASA Astrophysics Data System (ADS)

From 13 to 19 November 1989, the Naval Postgraduate School Atmospheric Optics Group acquired atmospheric optical turbulence measurements at the 31-inch Lowell Observatory telescope dome facility on Anderson Mesa, 16 km southeast of Flagstaff, Arizona. The parameters measured, the transverse coherence length and the isoplanatic angle, were part of an ongoing site survey for a large-scale, ground-based, synthetic aperture system (100 to 300 m baseline stellar interferometer). This report compiles, analyses and summarizes the acquired optical data. Also discussed are the synoptic meteorological events present during the data acquisition period.

Vaucher, Gail T.; Vaucher, Christopher A.; Walters, Donald L.

1991-01-01

372

Magnetic susceptibility and electronic specific heat of Anderson lattice with finite f-band width  

NASA Astrophysics Data System (ADS)

We study an extension of the periodic Anderson model by considering finite f-band width. A variational method recently developed, has been used to study the temperature dependence of the average valence of magnetic susceptibility chi(sub s) and electronic specific heat C(sub v) for different values of the f-band width. As f-band width increases, the low-temperature peak in chi(sub s) and C(sub v) becomes more broad and shifts towards the high-temperature region.

Panwar, Sunil; Singh, Ishwar

1994-11-01

373

Molecular analysis and intestinal expression of SAR1 genes and proteins in Anderson's disease (Chylomicron retention disease)  

PubMed Central

Background Anderson's disease (AD) or chylomicron retention disease (CMRD) is a very rare hereditary lipid malabsorption syndrome. In order to discover novel mutations in the SAR1B gene and to evaluate the expression, as compared to healthy subjects, of the Sar1 gene and protein paralogues in the intestine, we investigated three previously undescribed individuals with the disease. Methods The SAR1B, SAR1A and PCSK9 genes were sequenced. The expression of the SAR1B and SAR1A genes in intestinal biopsies of both normal individuals and patients was measured by RTqPCR. Immunohistochemistry using antibodies to recombinant Sar1 protein was used to evaluate the expression and localization of the Sar1 paralogues in the duodenal biopsies. Results Two patients had a novel SAR1B mutation (p.Asp48ThrfsX17). The third patient, who had a previously described SAR1B mutation (p.Leu28ArgfsX7), also had a p.Leu21dup variant of the PCSK9 gene. The expression of the SAR1B gene in duodenal biopsies from an AD/CMRD patient was significantly decreased whereas the expression of the SAR1A gene was significantly increased, as compared to healthy individuals. The Sar1 proteins were present in decreased amounts in enterocytes in duodenal biopsies from the patients as compared to those from healthy subjects. Conclusions Although the proteins encoded by the SAR1A and SAR1B genes are 90% identical, the increased expression of the SAR1A gene in AD/CMRD does not appear to compensate for the lack of the SAR1B protein. The PCSK9 variant, although reported to be associated with low levels of cholesterol, does not appear to exert any additional effect in this patient. The results provide further insight into the tissue-specific nature of AD/CMRD.

2011-01-01

374

Summary of data acquisition and field operations: Terra Resources, Anderson Canyon No. 3-17, Lincoln County, Wyoming; Terra Resources, North Anderson Canyon No. 40-16, Sweetwater County, Wyoming. Topical report, August 1989  

SciTech Connect

A summary is presented of open-hole data collected on two cooperative wells for the GRI Tight Gas Sands Program. The overall objective of gathering well data in the Frontier Formation is to identify and evaluate technological problems in formation evaluation and hydraulic fracturing. Open-hole data acquisition is emphasized for the Anderson Canyon No. 3-17, a full cooperative well (i.e., coring, logging, cased-hole stress testing, fracture monitoring). Data collected on the North Anderson Canyon No. 40-16, a partial cooperative well (i.e., logging only), is described in an appendix.

Not Available

1989-08-01

375

Anderson-Gruneisen parameter under high temperature in (Fe,Mn,Co,Mg)2SiO4  

NASA Astrophysics Data System (ADS)

The Anderson-Grüneisen parameter (?) is of considerable importance to Earth scientists because it sets limitations on the thermo-elastic properties of the lower mantle and core. However, there are several formulations on the Grüneisen parameter, which are in frequent use and predict varying dependence of d as a function of temperature. In this paper, the expressions for thermal expansion, thermal expansion coefficients and bulk modulus are obtained considering the anharmonic dependence on temperature and are applied to study these constants to (Fe,Mn,Co,Mg)2SiO4. Using the derived expressions, we have shown that different parameters on which the Anderson-Grüneisen parameter (?) depends are temperature dependent, but above all the Anderson-Grüneisen parameter (?) is independent of temperature. The results obtained have been found to be comparable to experimental data.

Gupta, S.; Goyal, S. C.

2012-07-01

376

Two new architectures based on Anderson-type polyoxoanions and cadmium fragments  

NASA Astrophysics Data System (ADS)

Two new hybrid compounds with cadmium cations/coordination complexes as linkers, (C 6H 5NO 2) 4[(H 2O) 14Cd 3(CrMo 6H 6O 24) 2] 1 (C 6H 5NO 2 = pyridine-4-carboxylic acid) and H[(H 2O) 2(C 6H 5NO 2)(C 6H 4NO 2)Cd] 2[CrMo 6H 6O 24]·9H 2O 2 (C 6H 5NO 2, C 6H 4NO 2 = pyridine-3-carboxylic acid), have been synthesized and characterized by elemental analyses, IR, TG, and single-crystal X-ray diffraction. Compound 1 crystallizes in the polar space group Pc and is made up of [CrMo 6H 6O 24] 3- polyoxoanions covalently linked by cadmium cations to yield an unprecedented one-dimensional chain, which represents the first example of one-dimensional assemblies based on Anderson-type POMs and cadmium cations. Adjacent inorganic chains are further in close contact by pyridine-4-carboxylic acid glues to form three-dimensional supramolecular polar networks via strong hydrogen-bonding interactions. Compound 2 exhibits a three-dimensional supramolecular channel framework constructed from cationic cadmium-pyridine-3-carboxylic acid coordination polymer sheets pillared by Anderson-type polyoxoanions, with dissociated water molecules situated in the channels. Furthermore, both of the compounds exhibit photoluminescent properties at ambient temperature.

An, Haiyan; Xu, Tieqi; Jia, Cuiying; Zheng, Hui; Mu, Wensheng

2009-09-01

377

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

378

Acoustically excited heated jets. 1: Internal excitation  

NASA Technical Reports Server (NTRS)

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

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

1988-01-01

379

The anderson's rotating interferometer and its application to binary star measurements. (French Title: L'interféromètre â?¡ rotation de john august anderson (1876-1956) et son application - la tentative de résolution de nouvelles binaires)  

NASA Astrophysics Data System (ADS)

Following the tests of interferometric observations carried out by Albert A. Michelson with the 2.5 m telescope of the Mount Wilson, George. E. Hale thinks that this technique could be applied to the measurement of close double stars. He asks John A. Anderson to produce an instrument allowing such measurements. The principle of the ocular rotating interferometer and the way of using it for the measurement of double stars are first described. Then the effects of atmospheric dispersion on the observation of the stellar interference fringes and the remedy that Anderson implements to compensate it are described. Images of the Anderson's interferometer are used to present the instrument and to describe its operation. Installed at the 2,5 m telescope, this instrument was used by Anderson and Paul W. Merrill to resolve the spectroscopic binary Capella for the first time, like a 'visual binary'. Moreover, Merrill took the measurement of two difficult visual pairs discovered by Aitken (kap UMa = A 1585 and nu2 Boo = A 1634) and tried to resolve some new visual binaries among stars known as binary spectroscopic, stars with composite spectra, variable stars and some bright stars, which led him to publish a list of 73 stars finally found simple. Finally, the remarks made by Merrill in conclusion of his work will be analyzed.

Bonneau, D.

2011-12-01

380

Coherence of Elementary Excitations in a Disordered Electron System  

NASA Astrophysics Data System (ADS)

The localization properties of the single-particle and collective electron excitations were investigated in the intentionally disordered GaAs/AlGaAs superlattices by weak-field magnetoresistance and Raman scattering. The localization length of the individual electron was found to be considerably larger than that of the collective excitations. This suggests that the disorder has a weaker effect on the electrons than on their collective motion and that the interaction which gives rise to the collective effects increases localization.

Pusep, Yu. A.; Ribeiro, M. B.; Carrasco, V. E.; Zanelatto, G.; Galzerani, J. C.

2005-04-01

381

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

382

Excitation of instability waves  

NASA Astrophysics Data System (ADS)

A brief survey is given on artificial excitation of instability waves in parallel flows. There are basically two categories of unstable flows: (1) convectively unstable and (2) absolutely unstable flows. The perturbation level in convectively unstable flows, e.g., boundary layers and most free shear flows, depends on the excitation only. On the other hand, absolutely unstable flows, e.g., wake flows and hot jets, do maintain fluctuations independent of an exterior excitation. Finally, effects of non-parallel mean flow and of varying boundary conditons on instability wave excitation are discussed.

Bechert, D. W.

1985-12-01

383

Anderson-Fabry disease: a histopathological study of three cases with observations on the mechanism of production of pain  

Microsoft Academic Search

A clinical review and histopathological study of three cases of Anderson-Fabry disease is presented and pathological changes in the central and peripheral nervous systems are reported, in some sites for the first time. These are telangiectatic changes in vessels of the sympathetic ganglia in the vertebral trunk; storage of glycolipid in pigmented cells of the substantia nigra and in anterior

Pauline Kahn

1973-01-01

384

MD Anderson study finds drug combination improves progression-free survival for women with metastatic breast cancer:  

Cancer.gov

In an international Phase III randomized study, everolimus, when combined with the hormonal therapy exemestane, has been shown to dramatically improve progression-free survival for women with metastatic breast cancer, according to research from The University of Texas MD Anderson Cancer Center.

385

A direct anchoring of Anderson-type polyoxometalates in aqueous media with tripodal ligands especially containing the carboxyl group.  

PubMed

Polyoxometalate-based organic-inorganic hybrids were synthesized by direct modification of the parent Anderson cluster with both the traditional tripodal ligand, CH3C(CH2OH)3, and a novel one containing a carboxyl group, CH3C(CH2OH)2(COOH), which was inaccessible from the traditional self-assembly protocol. PMID:24356499

Zhang, Jiangwei; Huang, Yichao; Zhang, Jin; She, Shan; Hao, Jian; Wei, Yongge

2014-02-21

386

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.

387

MD Anderson researchers find that breast cancer patients with BRCA gene are diagnosed almost 8 years earlier than generation before  

Cancer.gov

Women with a deleterious gene mutation are diagnosed with breast cancer almost eight years earlier than relatives of the previous generation who also had the disease and/or ovarian cancer, according to new research from the University of Texas MD Anderson Cancer Center.

388

LABOR QUALITY AND ECONOMICS DEVELOPMENT: DEVELOPMENT STRATEGIES FOR ANDERSON COUNTY, SOUTH CAROLINA, IN THE NEW GLOBAL COMPETITION  

Microsoft Academic Search

Industry came to South Carolina in the first half of this century to find cheap labor. By the 1990s, industry was coming in search of quality labor--a change whose pace accelerates as the decade of the nineties blends into the 21st century. Potential investors who raise inquiries with the Anderson County Office of Economic Development are less and less interested

William A. Ward

1997-01-01

389

Two Anderson impurities in a two-dimensional host with Rashba spin-orbit interaction  

NASA Astrophysics Data System (ADS)

We study the two-dimensional two-impurity Anderson model with additional Rashba spin-orbit interaction by means of the modified perturbation theory. The impurity Green's functions we construct exactly reproduce the first four spectral moments. We discuss the height and the width of the even or odd Kondo peaks as functions of the interimpurity distance and the Rashba energy ER (the strength of the Rashba spin-orbit interaction). For small impurity separations the Kondo temperature shows a nonmonotonic dependence on ER, being different in the even and the odd channels. We predict that the Kondo temperature has only an almost-linear dependence on ER and not an exponential increase with ER.

Ivanov, T. I.

2012-10-01

390

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

391

Carrier doping to a partially disordered state in the periodic Anderson model on a triangular lattice  

NASA Astrophysics Data System (ADS)

We investigate the effect of hole and electron doping to half-filling in the periodic Anderson model on a triangular lattice by the Hartree-Fock approximation at zero temperature. At half-filling, the system exhibits a partially disordered insulating state, in which a collinear antiferromagnetic order on an unfrustrated honeycomb subnetwork coexists with nonmagnetic state at the remaining sites. We find that the carrier doping destabilizes the partially disordered state, resulting in a phase separation to a doped metallic state with different magnetic order. The partially disordered state is restricted to the half-filled insulating case, while its metallic counterpart is obtained as a metastable state in a narrow electron doped region.

Hayami, Satoru; Udagawa, Masafumi; Motome, Yukitoshi

2012-12-01

392

Classical mapping for Hubbard operators: Application to the double-Anderson model.  

PubMed

A classical Cartesian mapping for Hubbard operators is developed to describe the nonequilibrium transport of an open quantum system with many electrons. The mapping of the Hubbard operators representing the many-body Hamiltonian is derived by using analogies from classical mappings of boson creation and annihilation operators vis-à-vis a coherent state representation. The approach provides qualitative results for a double quantum dot array (double Anderson impurity model) coupled to fermionic leads for a range of bias voltages, Coulomb couplings, and hopping terms. While the width and height of the conduction peaks show deviations from the master equation approach considered to be accurate in the limit of weak system-leads couplings and high temperatures, the Hubbard mapping captures all transport channels involving transition between many electron states, some of which are not captured by approximate nonequilibrium Green function closures. PMID:24880265

Li, Bin; Miller, William H; Levy, Tal J; Rabani, Eran

2014-05-28

393

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

394

Relativistic ionized gases: Ohm and Fourier laws from Anderson and Witting model equation  

NASA Astrophysics Data System (ADS)

The relativistic laws of Ohm and Fourier are determined for binary mixtures of electrons with protons or photons subjected to external electromagnetic fields, by using the Anderson and Witting model equation. General expressions for the electrical and thermal conductivities for relativistic degenerate ionized gas mixtures are determined and explicit expressions for the transport coefficients are given for the particular cases: (i) a non-relativistic mixture of protons and non-degenerate electrons; (ii) an ultra-relativistic mixture of photons and non-degenerate electrons; (iii) a non-relativistic mixture of protons and completely degenerate electrons; (iv) an ultra-relativistic mixture of photons and completely degenerate electrons and (v) a mixture of non-relativistic protons and ultra-relativistic completely degenerate electrons.

Kremer, G. M.; Patsko, C. H.

2003-05-01

395

Anderson's Conjecture and the Maximal Monoid Class Over which Projective Modules are Free  

NASA Astrophysics Data System (ADS)

A positive solution is given to a conjecture of D. F. Anderson (Pacific J. Math. 79(1978), 5-17, p. 11) concerning freeness of finitely generated projective modules over normal monoid algebras. In the special case of torsion divisor class groups, or equivalently, the case of an integral extension, this conjecture was proved in 1982 (see Gubeladze, Generalized Serre problem for affine rings generated by monomials, Izdat. Tbiliss. Gos. Univ., Tbilisi, 1982, and Chouinard, MR 84c: 13009). Using that result, the author obtains a description of the maximal class of commutative monoids satisfying the cancellation condition for which all finitely generated projective modules over the corresponding semigroup algebra (with any principal ideal domain as coefficient ring) are free. Namely, this class turns out to be the so-called "seminormal" monoids. By the same token a complete answer is given to some questions posed by Chouinard in the paper cited above.Bibliography: 16 titles.

Gubeladze, I. D.

1989-02-01

396

Laparoscopic Anderson-Hynes procedure as a treatment of ureteropelvic junction obstruction caused by fibroepithelial polyp.  

PubMed

Fibroepithelial polyps (FEPs) are rare benign ureteral neoplasms of mesodermal origin. As an intrinsic cause of ureteropelvic junction obstruction (UPJO) they are very uncommon. Excretory urography and diuretic renography used by many urologists to diagnose a UPJO may not detect the ureteral polyp. We present a case of ureteropelvic junction obstruction caused by a fibroepithelial polyp, which was not diagnosed preoperatively. The patient underwent successful laparoscopic excision of the polyp with Anderson-Hynes pyeloplasty. We believe that laparoscopy is a useful, minimally invasive operative technique in the treatment of FEPs and may be considered a procedure of choice in large polyps, in which cases the endoscopic procedure is difficult or impossible to perform. PMID:24501609

Szydelko, Tomasz; Tuchendler, Tomasz; Litarski, Adam; Urba?czyk, Grzegorz; Apozna?ski, Wojciech; Janczak, Dariusz

2013-12-01

397

Laparoscopic Anderson-Hynes procedure as a treatment of ureteropelvic junction obstruction caused by fibroepithelial polyp  

PubMed Central

Fibroepithelial polyps (FEPs) are rare benign ureteral neoplasms of mesodermal origin. As an intrinsic cause of ureteropelvic junction obstruction (UPJO) they are very uncommon. Excretory urography and diuretic renography used by many urologists to diagnose a UPJO may not detect the ureteral polyp. We present a case of ureteropelvic junction obstruction caused by a fibroepithelial polyp, which was not diagnosed preoperatively. The patient underwent successful laparoscopic excision of the polyp with Anderson-Hynes pyeloplasty. We believe that laparoscopy is a useful, minimally invasive operative technique in the treatment of FEPs and may be considered a procedure of choice in large polyps, in which cases the endoscopic procedure is difficult or impossible to perform.

Tuchendler, Tomasz; Litarski, Adam; Urbanczyk, Grzegorz; Apoznanski, Wojciech; Janczak, Dariusz

2013-01-01

398

Classical mapping for Hubbard operators: Application to the double-Anderson model  

NASA Astrophysics Data System (ADS)

A classical Cartesian mapping for Hubbard operators is developed to describe the nonequilibrium transport of an open quantum system with many electrons. The mapping of the Hubbard operators representing the many-body Hamiltonian is derived by using analogies from classical mappings of boson creation and annihilation operators vis-à-vis a coherent state representation. The approach provides qualitative results for a double quantum dot array (double Anderson impurity model) coupled to fermionic leads for a range of bias voltages, Coulomb couplings, and hopping terms. While the width and height of the conduction peaks show deviations from the master equation approach considered to be accurate in the limit of weak system-leads couplings and high temperatures, the Hubbard mapping captures all transport channels involving transition between many electron states, some of which are not captured by approximate nonequilibrium Green function closures.

Li, Bin; Miller, William H.; Levy, Tal J.; Rabani, Eran

2014-05-01

399

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

1996-02-08

400

Volcanic ash dispersed in the Wyodak-Anderson coal bed, Powder River Basin, Wyoming  

USGS Publications Warehouse

Minerals derived from air-fall volcanic ash were found in two zones in the upper Paleocene Wyodak-Anderson coal bed of the Fort Union Formation in the Powder River Basin of Wyoming, and are the first reported evidence of such volcanic material in this thick (> 20 m) coal bed. The volcanic minerals occur in zones that are not visually obvious because they contain little or no clay. These zones were located by geophysical logs of the boreholes and X-ray radiography of the cores. The zones correspond to two of a series of incremental core samples of the coal bed that have anomalous concentrations of Zr, Ba, Nb, Sr, and P2O5. Two suites of minerals were found in both of the high-density zones. A primary suite (not authigenic) consists of silt-sized quartz grains, biotite, and minor zircon. A minor suite consists of authigenic minerals, including calcite, pyrite, kaolinite, quartz, anatase, barite, and an alumino-phosphate (crandallite?). The original volcanic ash is inferred to have consisted of silica glass containing phenocrysts of quartz, biotite, zircon, and possibly, associated feldspars, pyroxenes, and amphiboles. The glass, as well as the less stable minerals, probably dissolved relatively quickly and contributed to the minor authigenic mineral suite or was removed from the peat as a result of the prevailing hydrologic conditions present in a raised peat formation. This type of volcanic ash suggests that suggests that volcanic material could have rained on the peat; this fallout may have also had a fertilizing effect on the peat by providing nutrients essential for plant growth thus contributing to the thick accumulations of the Wyodak-Anderson bed. Notwithstanding, the presence of these minerals provides evidence for the contribution by volcanic sources to the mineral content of coal, but not as tonsteins. ?? 1991.

Triplehorn, D. M.; Stanton, R. W.; Ruppert, L. F.; Crowley, S. S.

1991-01-01

401

Quantum fluctuations and excitations in antiferromagnetic quasicrystals  

SciTech Connect

We study the effects of quantum fluctuations and the excitation spectrum for the antiferromagnetic Heisenberg model on a two-dimensional quasicrystal, by numerically solving linear spin-wave theory on finite approximants of the octagonal tiling. Previous quantum Monte Carlo results for the distribution of local staggered magnetic moments and the static spin structure factor are reproduced well within this approximate scheme. Furthermore, the magnetic excitation spectrum consists of magnonlike low-energy modes, as well as dispersionless high-energy states of multifractal nature. The dynamical spin structure factor, accessible to inelastic neutron scattering, exhibits linear-soft modes at low energies, self-similar structures with bifurcations emerging at intermediate energies, and flat bands in high-energy regions. We find that the distribution of local staggered moments stemming from the inhomogeneity of the quasiperiodic structure leads to a characteristic energy spread in the local dynamical spin susceptibility, implying distinct nuclear magnetic resonance spectra, specific for different local environments.

Wessel, Stefan [Institut fuer Theoretische Physik III, Universitaet Stuttgart, D-70550 Stuttgart (Germany); Milat, Igor [Theoretische Physik, ETH Zuerich, CH-8093 Zurich (Switzerland)

2005-03-01

402

Anomalous localization in low-dimensional systems with correlated disorder  

NASA Astrophysics Data System (ADS)

This review presents a unified view on the problem of Anderson localization in one-dimensional weakly disordered systems with short-range and long-range statistical correlations in random potentials. The following models are analyzed: the models with continuous potentials, the tight-binding models of the Anderson type, and various Kronig-Penney models with different types of perturbations. Main attention is paid to the methods of obtaining the localization length in dependence on the controlling parameters of the models. Specific interest is in an emergence of effective mobility edges due to certain long-range correlations in a disorder. The predictions of the theoretical and numerical analysis are compared to recent experiments on microwave transmission through randomly filled waveguides.

Izrailev, F. M.; Krokhin, A. A.; Makarov, N. M.

2012-03-01

403

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

404

Energy localization in nonlinear lattices  

Microsoft Academic Search

We discuss the process by which energy, initially evenly distributed in a nonlinear lattice, can localize itself into large amplitude excitations. We show that the standard modulational instability mechanism, which can initiate the process by the formation of small amplitude breathers, is completed efficiently, in the presence of discreteness, by energy exchange mechanisms between the nonlinear excitations which favor systematically

Thierry Dauxois; Michel Peyrard

1993-01-01

405

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

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

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

406

A narrow band contribution with Anderson localization in Ag-doped layered cobaltites Bi2Ba3Co2Oy  

Microsoft Academic Search

We have systematically investigated the influence of the Ag doping on magnetization M(T), resistivity &rgr;(T), thermoelectric power S(T), and thermal conductivity ?(T) in the layered cobaltites Bi2Ba3?xAgxCo2Oy(0?x?2) samples. For Ag-doped sample, the magnetic susceptibility indicates the ground state is dominated by the low-spin states of the combination of Co3+ and Co4+. The metal-insulator transition existing in Ag-free sample is suppressed

R. Ang; Y. P. Sun; X. Luo; W. H. Song

2007-01-01

407

A narrow band contribution with Anderson localization in Ag-doped layered cobaltites Bi2Ba3Co2Oy  

Microsoft Academic Search

We have systematically investigated the influence of the Ag doping on magnetization M(T), resistivity rho(T), thermoelectric power S(T), and thermal conductivity kappa(T) in the layered cobaltites Bi2Ba3-xAgxCo2Oy (0<=x<=2) samples. For Ag-doped sample, the magnetic susceptibility indicates the ground state is dominated by the low-spin states of the combination of Co3+ and Co4+. The metal-insulator transition existing in Ag-free sample is

R. Ang; Y. P. Sun; X. Luo; W. H. Song

2007-01-01

408

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

409

Magnetostrictive resonance excitation.  

National Technical Information Service (NTIS)

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 co...

R. B. Schwartz V. T. Kuokkala

1990-01-01

410

Identification of Mott insulators and Anderson insulators in self-assembled gold nanoparticles thin films  

NASA Astrophysics Data System (ADS)

How the interparticle tunnelling affects the charge conduction of self-assembled gold nanoparticles is studied by three means: tuning the tunnel barrier width by different molecule modification and by substrate bending, and tuning the barrier height by high-dose electron beam exposure. All approaches indicate that the metal-Mott insulator transition is governed predominantly by the interparticle coupling strength, which can be quantified by the room temperature sheet resistance. The Hubbard gap, following the prediction of quantum fluctuation theory, reduces to zero rapidly as the sheet resistance decreases to the quantum resistance. At very low temperature, the fate of devices near the Mott transition depends on the strength of disorder. The charge conduction is from nearest-neighbour hopping to co-tunnelling between nanoparticles in Mott insulators whereas it is from variable-range hopping through charge puddles in Anderson insulators. When the two-dimensional nanoparticle network is under a unidirectional strain, the interparticle coupling becomes anisotropic so the average sheet resistance is required to describe the charge conduction.How the interparticle tunnelling affects the charge conduction of self-assembled gold nanoparticles is studied by three means: tuning the tunnel barrier width by different molecule modification and by substrate bending, and tuning the barrier height by high-dose electron beam exposure. All approaches indicate that the metal-Mott insulator transition is governed predominantly by the interparticle coupling strength, which can be quantified by the room temperature sheet resistance. The Hubbard gap, following the prediction of quantum fluctuation theory, reduces to zero rapidly as the sheet resistance decreases to the quantum resistance. At very low temperature, the fate of devices near the Mott transition depends on the strength of disorder. The charge conduction is from nearest-neighbour hopping to co-tunnelling between nanoparticles in Mott insulators whereas it is from variable-range hopping through charge puddles in Anderson insulators. When the two-dimensional nanoparticle network is under a unidirectional strain, the interparticle coupling becomes anisotropic so the average sheet resistance is required to describe the charge conduction. Electronic supplementary information (ESI) available. See DOI: 10.1039/c3nr06627d

Jiang, Cheng-Wei; Ni, I.-Chih; Tzeng, Shien-Der; Wu, Cen-Shawn; Kuo, Watson

2014-05-01

411

Excitation Mechanisms of RE Ions in Semiconductors  

NASA Astrophysics Data System (ADS)

This chapter presents an overview of the mechanisms responsible for the excitation of optically active rare-earth (RE) ions in semiconductors. Besides resonant excitation of the RE 4f shell, several non-resonant processes can take place in which the host is excited first. These indirect mechanisms involve nonradiative transfer of the recombination energy of electrons and holes to nearby RE ions. Distinct excitation processes arise because of the various conditions under which the electron may recombine with a hole. The different possibilities are presented and discussed in the first part of this chapter. Carriers of opposite charge bind to each other to form either a free exciton or a trapped (bound) exciton. In the latter case, the trapping can arise from the incorporation of RE ions which induces distortions of the host lattice. The exciton trapping can also be due to an impurity, a local defect or even an extended defect. Other possible mechanisms involve the capture of an electron by the 5d shell changing the valence state from trivalent to divalent with the subsequent capture of a hole. Finally, the role of impurities associated with donor-acceptor pairs in the recombination of electrons and holes with energy transfer to RE ions is discussed. In the second part of this chapter the specific case of RE-doped GaN is considered. Results are presented to show that local defects play a major role in the excitation process by binding excitons with a subsequent energy transfer to RE ions. A general modelling of the RE excitation mechanism mediated by bound excitons (BE) is presented and discussed. Finally, experiments using two excitation sources are shown to give valuable information concerning the RE-related defects.

Braud, Alain

412

Quantum criticality in the two-channel pseudogap Anderson model: A test of the non-crossing approximation  

NASA Astrophysics Data System (ADS)

We investigate the dynamical properties of the two-channel Anderson model using the noncrossing approximation (NCA) supplemented by numerical renormalization-group calculations. We provide evidence supporting the conventional wisdom that the NCA gives reliable results for the standard two-channel Anderson model of a magnetic impurity in a metal. We extend the analysis to the pseudogap two-channel model describing a semi-metallic host with a density of states that vanishes in power-law fashion at the Fermi energy. This model exhibits continuous quantum phase transitions between weak- and strong-coupling phases. The NCA is shown to reproduce the correct qualitative features of the pseudogap model, including the phase diagram, and to yield critical exponents in excellent agreement with the NRG and exact results. The forms of the dynamical magnetic susceptibility and impurity Green's function at the fixed points are suggestive of frequency-over-temperature scaling.

Zamani, Farzaneh; Chowdhury, Tathagata; Ribeiro, Pedro; Ingersent, Kevin; Kirchner, Stefan

2013-03-01

413

Violent Video Games: Specific Effects Violent Content Aggressive Thoughts Behavior Craig A. Anderson Nicholas L. Carnage Mandy Flanagan Arline J. Benjamin Jr. Janie Eubank Jeffery C. Valentine  

EPA Pesticide Factsheets

Did you mean: Violent Video Games: Specific Effects Violent Content Aggressive Thoughts Behavior Craig A. Anderson Nicholas L. Carnage Mandy Flanagan Arline J. Benjamin Jr. Janie Eubank Jeffery C. Valentine ?

414

Surface plasmon excitation in a hollow prism  

NASA Astrophysics Data System (ADS)

We design a hollow prism to excite surface plasmon. The prism is coated with polymethyl methacrylate (PMMA) containing rhodamine 6G (Rh6G) and 30 nm thick Ag film on the inner surface. After filling the hollow prism with alcohol and CS2, we measured the reflectance angle spectrum and observed the significant absorption, which indicates that the localized surface plasmon is excited at the Ag-PMMA interface. This hollow prism structure may be used in analyzing the composition and reaction process of the liquid or gas at the same time.

Li, Jin; Zhang, Yundong; Li, Hanyang; Ma, Lei; Yua, Ping

2012-04-01

415

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

416

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.

417

Anderson-Fabry disease: clinical manifestations and impact of disease in a cohort of 98 hemizygous males  

Microsoft Academic Search

OBJECTIVESTo determine the natural history of Anderson-Fabry disease (AFD) as a baseline for efficacy assessment of potentially therapeutic drugs.DESIGNThe first large cross sectional study of a patient cohort from the AFD clinical and genetic register (UK), maintained for the last 15 years.MEASURESPrevalence, mortality, frequency of AFD manifestations, and impact of disease on patient lives, assessed from the AFD register and

K D MacDermot; A Holmes; A H Miners

2001-01-01

418

MD Anderson-led study finds metabolic protein wields phosphate group to activate cancer-promoting genes  

Cancer.gov

A metabolic protein that nourishes cancer cells also activates tumor-promoting genes by loosening part of the packaging that entwines DNA to make up chromosomes, a team led by scientists at The University of Texas MD Anderson Cancer Center reports in the Aug. 16 issue of Cell. Working in cell lines and mouse models of glioblastoma multiforme, the most lethal form of brain tumor, the team showed that pyruvate kinase M2 (PKM2) fuels tumor growth by influencing a histone protein.

419

The Central Control Room Man-Machine Interface at the Clinton P. Anderson Meson Physics Facility (LAMPF)  

Microsoft Academic Search

The control system for the Clinton P. Anderson Meson Physics Facility (LANPF) is organized around an on-line digital computer. Accelerator operations are conducted from the Central Control Room (CCR) where two identical but independent operator consoles provide the man-machine interface. This paper traces the evolution of the man-machine interface from the initial concepts of a computer control system. Special emphasis

B. L. Hartway; J. Bergstein; C. M. Plopper

1973-01-01

420

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.

421

MD Anderson study finds majority of older, early-stage breast cancer patients benefit from radiation after lumpectomy  

Cancer.gov

For the majority of older, early-stage breast cancer patients, radiation therapy following breast conserving surgery may help prevent the need for a later mastectomy, according to research from The University of Texas MD Anderson Cancer Center. The findings, published in the journal Cancer, are contrary to current national treatment guidelines, which recommend that older women with early stage, estrogen-positive disease be treated with lumpectomy followed by estrogen blocker therapy alone -- and forgo radiation therapy post-surgery.

422

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

423

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.  

PubMed

The number of proton and carbon ion therapy centers is increasing; however, since the publication of the International Commission on Radiation Units and Measurements report, there has been no dedicated report dealing with proton therapy quality assurance. The purpose of this article is to describe the quality assurance procedures performed on the passively scattered proton therapy beams at The University of Texas M. D. Anderson Cancer Center Proton Therapy Center in Houston. The majorities of these procedures are either adopted from procedures outlined in the American Association of Physicists in Medical Task Group (TG) 40 report or are a modified version of the TG 40 procedures. In addition, new procedures, which were designed specifically to be applicable to the synchrotron at the author's center, have been implemented. The authors' procedures were developed and customized to ensure patient safety and accurate operation of synchrotron to within explicit limits. This article describes these procedures and can be used by others as a guideline for developing QA procedures based on particle accelerator specific parameters and local regulations pertinent to any new facility. PMID:19610316

Arjomandy, Bijan; Sahoo, Narayan; Zhu, X Ronald; Zullo, John R; Wu, Richard Y; Zhu, Mingping; Ding, Xiaoning; Martin, Craig; Ciangaru, George; Gillin, Michael T

2009-06-01

424

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

425

Linguistic validation of the Greek M.D. Anderson Symptom Inventory - Head and Neck Module  

PubMed Central

Background Our goal is to linguistically validate the Greek translation of the M.D. Anderson Symptom Inventory Index – Head and Neck Module. Patients & Methods Following forward and backward translation of the previously validated head and neck cancer specific items of the English MDASI-HN into Greek (G-MDASI-HN), it was administered along with a cognitive debriefing to head and neck cancer patients able to read and understand Greek. Individual and group responses are presented using descriptive statistics. Results From 02/2009 through 06/2009 30 subjects with head and neck cancer completed the G-MDASI-HN followed by completion of the accompanying cognitive debriefing. Ninety-eight percent of the individual G-MDASI-HN items were completed. “Voice” item was not completed by 5 patients. Average time to complete the G-MDASI-HN was 13.3 minutes. Average ease of completion was rated at 1.21 on a 0 to 10 scale with “0” being “very easy” and “10” being “very hard”. Only 10% of patients reported trouble completing any item, namely “distress” and “numbness”. Conclusions The Greek-MDASI-HN is linguistically valid and a patient-reported instrument that can be used both in outcomes research and as a clinical tool.

Gunn, G. Brandon; Koukourakis, Michael I.; Mendoza, Tito R.; Cleeland, Charles S.; Rosenthal, David I.

2012-01-01

426

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

427

Identification of Mott insulators and Anderson insulators in self-assembled gold nanoparticles thin films.  

PubMed

How the interparticle tunnelling affects the charge conduction of self-assembled gold nanoparticles is studied by three means: tuning the tunnel barrier width by different molecule modification and by substrate bending, and tuning the barrier height by high-dose electron beam exposure. All approaches indicate that the metal-Mott insulator transition is governed predominantly by the interparticle coupling strength, which can be quantified by the room temperature sheet resistance. The Hubbard gap, following the prediction of quantum fluctuation theory, reduces to zero rapidly as the sheet resistance decreases to the quantum resistance. At very low temperature, the fate of devices near the Mott transition depends on the strength of disorder. The charge conduction is from nearest-neighbour hopping to co-tunnelling between nanoparticles in Mott insulators whereas it is from variable-range hopping through charge puddles in Anderson insulators. When the two-dimensional nanoparticle network is under a unidirectional strain, the interparticle coupling becomes anisotropic so the average sheet resistance is required to describe the charge conduction. PMID:24752439

Jiang, Cheng-Wei; Ni, I-Chih; Tzeng, Shien-Der; Wu, Cen-Shawn; Kuo, Watson

2014-06-01

428

Evaluating Quality in Clinical Cancer Research: The M.D. Anderson Cancer Center Experience  

PubMed Central

Background Despite the unquestionable importance of clinically oriented research designed to test the safety and efficacy of new therapies in patients with malignant disease, there is limited information regarding strategies to evaluate the quality of such efforts at academic institutions. Methods To address this issue, a committee of senior faculty at the University of Texas M.D. Anderson Cancer Center established specific criteria by which investigators from all departments engaged in clinical research could be formally evaluated. Scoring criteria were established and revised based on the results of a pilot study. Beginning in January 2004, the committee evaluated all faculty involved in clinical research within 35 departments. Scores for individual faculty members were assigned on a scale of 1 (outstanding) to 5; a score of 3 was set as the standard for the institution. Each department also received a score. The results of the evaluation were shared with departmental chairs and the Chief Academic Officer. Results 392 faculty were evaluated. The median score was 3. Full professors more frequently received a score of 1, but all faculty ranks received scores of 4 and 5. As a group, tenure/tenure track faculty achieved superior scores compared to nontenure track faculty. Conclusions Based on our experience, we believe it is possible to conduct a rigorous consensus-based evaluation of the quality of clinical cancer research being conducted at an academic medical center. It is reasonable to suggest such evaluations can be used as a management tool and may lead to higher-quality clinical research.

Cox, James D.; Giralt, Sergio A.; Veazie, Mary L.; Ajani, Jaffer A.; Bruner, Janet M.; Chan, Ka Wah; Hittelman, Walter N.; Hunt, Kelly K.; Iyer, Revathy B.; Karp, Daniel D.; Kuban, Deborah A.; Lippman, Scott M.; Raad, Issam I.; Rodriguez-Bigas, Miguel A.; Zwelling, Leonard A.; Markman, Maurie

2009-01-01

429

Response to the commentaries of Melissa S Anderson and Murray J Dyck.  

PubMed

Anderson and Dyck claim that the current trend of almost exclusively using citation-based evaluative metrics to assess the research output of scholars is unsound. I agree with them in this, but I feel that, for practical reasons, this system will not disappear in the near future, so we must concentrate on making it fairer. Both commentators doubt whether numerically expressing each contributor's relative contribution is feasible. I admit that an important precondition for this task is the possibility of an informed, democratic debate among equals about the relative contribution of each contributor to the article. Mechanisms should be established to protect vulnerable researchers in the academic field in the same way as safeguards exist today to protect vulnerable research participants. Theoretically, however, I think that the fair allocation of authorship credit is possible, and much of this task is already being performed routinely when contributors determine the order of their names in the byline, being well aware of the widespread assumption that this order mostly mirrors the order of their relative contributions. All they would have to do as an additional task is to express this order in numbers. If they cannot reach a consensus, they could always choose not to express their relative contribution in numbers, in which case the presumption would be that they contributed equally. My proposal could, at best, make the system fairer and, at worst, not reduce the options that evaluators already have. PMID:23038802

Kovacs, Jozsef

2013-08-01

430

Suitability of Palestine salt dome, Anderson Co. , Texas for disposal of high-level radioactive waste  

SciTech Connect

The suitability of Palestine salt dome, in Anderson County, Texas, is in serious doubt for a repository to isolate high-level nuclear waste because of abandoned salt brining operations. The random geographic and spatial occurrence of 15 collapse sinks over the dome may prevent safe construction of the necessary surface installations for a repository. The dissolution of salt between the caprock and dome, from at least 15 brine wells up to 500 feet deep, may permit increased rates of salt dissolution long into future geologic time. The subsurface dissolution is occurring at a rate difficult, if not impossible, to assess or to calculate. It cannot be shown that this dissolution rate is insignificant to the integrity of a future repository or to ancillary features. The most recent significant collapse was 36 feet in diameter and took place in 1972. The other collapses ranged from 27 to 105 feet in diameter and from 1.5 to more than 15 feet in depth. ONWI recommends that this dome be removed from consideration as a candidate site.

Patchick, P.F.

1980-01-01

431

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

432

Quantum Monte Carlo simulations of the degenerate single-impurity Anderson model  

NASA Astrophysics Data System (ADS)

We present results of quantum Monte Carlo simulations of the degenerate, single-impurity, Anderson model. Using maximum-entropy methods, we performed the analytic continuation of the imaginary-time Green's functions produced by these simulations to obtain their real-frequency, single-particle, spectral densities for degeneracies of N=2, 4, and 6. Incorporating higher degeneracies into the model enables us, on the one hand, to compare Monte Carlo results with the self-consistent large-N approximation (NCA) and numerical-renormalization-group calculations (NGR) and, on the other hand, to bring the models closer to the physical systems. The low temperatures reached in our calculations are comparable to, or even lower than, the corresponding Kondo temperatures. The NCA and NRG calculations were found to show qualitatively good agreement with our results: the Kondo temperature increases with increasing degeneracy, and the amplitude of the side peaks in the spectral density decreases as degeneracy increases while the half-width of these peaks increases.

Bon?a, J.; Gubernatis, J. E.

1993-05-01

433

The paleomagnetic record of late Quaternary secular variation from Anderson Pond, Tennessee  

NASA Astrophysics Data System (ADS)

A paleomagnetic record of the Earth's secular variation between 12,500 and 21,000 years B.P. has been recovered from two replicate wet-sediment cores of Anderson Pond, Tennessee (36.0°N, 274.5°E). Error analysis indicates that the cores are correctly oriented in the vertical plane, but that some azimuthal offsets of individual core segments did occur. These offsets were corrected by cross-correlation between the two replicate cores. The final paleomagnetic data set is internally consistent and easily correlated with other high-resolution late Quaternary paleomagnetic records from the eastern United States. There is no evidence for any regional excursion or global reversal between 12,500 and 21,000 years B.P. Time series analysis indicates that both the field-vector and VGP distributions are non-Fisherian and distinctly "far-sided" compared to the axial-dipole expectation. The far-sided effect is interpreted to be geomagnetic in source rather than an error in the DRM/PDRM mechanism. Spectral analysis suggests that the secular variation is due primarily to a single irregular waveform with a period of about 3200 years. This is interpreted to result from zonal drift of the non-dipole field past Tennessee at the rate of about 0.11°/year.

Lund, Steve P.; Banerjee, Subir K.

1985-02-01

434

Anderson lattice in the intermediate valence compound Ce3Ni2B2N3-?  

NASA Astrophysics Data System (ADS)

We have studied magnetic, thermodynamic, and transport properties of Ce3Ni2B2N3-? and its solid solution with the Tc?13 K superconductor La3Ni2B2N3-?. The solid solution (La,Ce)3Ni2B2N3-? reveals a rapid reduction of Tc by increasing the Ce content with a complete suppression of superconductivity at the composition La2.85Ce0.15Ni2B2N3-?. The low-temperature properties characterize Ce3Ni2B2N3-? as an intermediate valence system with a moderately enhanced Sommerfeld value ??54 mJ/mol K2 and a susceptibility ?0?1.6×10-3 emu/mol, increased by about one order of magnitude as compared to the respective value ?0?0.2×10-3 emu/mol of superconducting La3Ni2B2N3-? (?=26 mJ/mol K2) which serves as reference with a nonmagnetic rare earth ion. The electrical resistivity and thermoelectric power of Ce3Ni2B2N3-? are analyzed in terms of the degenerate Anderson lattice model revealing a characteristic Kondo temperature TKALM~1100 K.

Ali, Tahir; Bauer, Ernst; Hilscher, Gerfried; Michor, Herwig

2011-03-01

435

Anderson type polyoxomolybdate as cathode material of lithium battery and its reaction mechanism  

NASA Astrophysics Data System (ADS)

Anderson type polyoxomolybdate, Na3[AlMo6O24H6] (NAM), was studied as the cathode material of lithium battery. Discharge capacity and cycle performance of NAM cathode largely depended on the mixing method of active material with conductive additive and the type of conductive additive. NAM ball-milled with ketjen black (KB) showed very high initial discharge capacity of 437 mAh g-1 and the most stable cycle performance with high capacity retention of 91.2% after 50 cycles. The results of ex situ XRD showed that the crystal structure changes of NAM was irreversible during the first discharge-charge process and changed to amorphous state completely after 5 cycles. Ex situ Raman spectra showed the structure of molecular cluster ion [AlMo6O24H6]3- is stable during the discharge process. These data have demonstrated that the high discharge capacity and stable cycle performance of NAM originate in the improvement of the electric conductivity and the stable molecular cluster ion [AlMo6O24H6]3- that is independent from the recoverability of its crystal structure.

Ni, Erfu; Uematsu, Shinya; Sonoyama, Noriyuki

2014-12-01

436

Disorder in quantum vacuum: Casimir-induced localization of matter waves.  

PubMed

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. PMID:21231273

Moreno, G A; Messina, R; Dalvit, D A R; Lambrecht, A; Maia Neto, P A; Reynaud, S

2010-11-19

437

Dynamical Localization for Discrete and Continuous Random Schrödinger Operators  

NASA Astrophysics Data System (ADS)

We show for a large class of random Schrödinger operators Ho on and on that dynamical localization holds, i.e. that, with probability one, for a suitable energy interval I and for q a positive real, Here ? is a function of sufficiently rapid decrease, and PI(Ho) is the spectral projector of Ho corresponding to the interval I. The result is obtained through the control of the decay of the eigenfunctions of Ho and covers, in the discrete case, the Anderson tight-binding model with Bernoulli potential (dimension ? = 1) or singular potential (? > 1), and in the continuous case Anderson as well as random Landau Hamiltonians.

Germinet, F.; De Bièvre, S.

438

Shear layer excitation, experiment versus theory  

NASA Technical Reports Server (NTRS)

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

Bechert, D. W.; Stahl, B.

1984-01-01

439

Testing the excitability of human motoneurons.  

PubMed

The responsiveness of the human central nervous system can change profoundly with exercise, injury, disuse, or disease. Changes occur at both cortical and spinal levels but in most cases excitability of the motoneuron pool must be assessed to localize accurately the site of adaptation. Hence, it is critical to understand, and employ correctly, the methods to test motoneuron excitability in humans. Several techniques exist and each has its advantages and disadvantages. This review examines the most common techniques that use evoked compound muscle action potentials to test the excitability of the motoneuron pool and describes the merits and limitations of each. The techniques discussed are the H-reflex, F-wave, tendon jerk, V-wave, cervicomedullary motor evoked potential (CMEP), and motor evoked potential (MEP). A number of limitations with these techniques are presented. PMID:23630483

McNeil, Chris J; Butler, Jane E; Taylor, Janet L; Gandevia, Simon C

2013-01-01

440

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

441

Temperature and excitable cells  

PubMed Central

Temperature affects a host of biological processes, one of which is the conduction velocity of action potentials (AP). The velocity-temperature profile of APs has remained remarkably conserved across excitable animal and plant cells. Herein, we will not analyze this behavior in terms of temperature sensitivities of single molecules (e.g., ion channels), but rather we present a phenomenological thermodynamic interpretation. By assuming that APs are acoustic phenomena, one arrives at testable predictions about the temperature-dependence of the macroscopic material properties of the excitable cell membrane. These material properties set constraints on the excitability of a cell membrane and allow us to hypothesize about its typical relaxation timescales. The presented approach—by virtue of its thermodynamic nature—is by no means limited to temperature. It applies equally well to all thermodynamic variables (e.g., mechanical stretch, pH, ion concentrations, etc.) and to underline this argument we discuss some implications and predictions for sensory physiology.

Fillafer, Christian; Schneider, Matthias F

2013-01-01

442

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

443

Fractal superconductivity near localization threshold  

SciTech Connect

We develop a semi-quantitative theory of electron pairing and resulting superconductivity in bulk 'poor conductors' in which Fermi energy E{sub F} is located in the region of localized states not so far from the Anderson mobility edge E{sub c}. We assume attractive interaction between electrons near the Fermi surface. We review the existing theories and experimental data and argue that a large class of disordered films is described by this model. Our theoretical analysis is based on analytical treatment of pairing correlations, described in the basis of the exact single-particle eigenstates of the 3D Anderson model, which we combine with numerical data on eigenfunction correlations. Fractal nature of critical wavefunction's correlations is shown to be crucial for the physics of these systems. We identify three distinct phases: 'critical' superconductive state formed at E{sub F} = E{sub c}, superconducting state with a strong pseudo-gap, realized due to pairing of weakly localized electrons and insulating state realized at E{sub F} still deeper inside a localized band. The 'critical' superconducting phase is characterized by the enhancement of the transition temperature with respect to BCS result, by the inhomogeneous spatial distribution of superconductive order parameter and local density of states. The major new feature of the pseudo-gapped state is the presence of two independent energy scales: superconducting gap {Delta}, that is due to many-body correlations and a new 'pseudo-gap' energy scale {Delta}{sub P} which characterizes typical binding energy of localized electron pairs and leads to the insulating behavior of the resistivity as a function of temperature above superconductive T{sub c}. Two gap nature of the pseudo-gapped superconductor is shown to lead to specific features seen in scanning tunneling spectroscopy and point-contact Andreev spectroscopy. We predict that pseudo-gapped superconducting state demonstrates anomalous behavior of the optical spectral weight. The insulating state is realized due to the presence of local pairing gap but without superconducting correlations; it is characterized by a hard insulating gap in the density of single electrons and by purely activated low-temperature resistivity ln R(T) {approx} 1/T. Based on these results we propose a new 'pseudo-spin' scenario of superconductor-insulator transition and argue that it is realized in a particular class of disordered superconducting films. We conclude by the discussion of the experimental predictions of the theory and the theoretical issues that remain unsolved.

Feigel'man, M.V., E-mail: feigel@landau.ac.r [L.D. Landau Institute for Theoretical Physics, Kosygin st. 2, Moscow 119334 (Russian Federation); Moscow Institute of Physics and Technology, Moscow 141700 (Russian Federation); Ioffe, L.B., E-mail: ioffe@physics.rutgers.ed [L.D. Landau Institute for Theoretical Physics, Kosygin st. 2, Moscow 119334 (Russian Federation); Department of Physics and Astronomy, Rutgers University, Piscataway, NJ 08854 (United States); CNRS and Universite Paris-Sud, UMR 8626, LPTMS, Orsay Cedex, F-91405 France (France); Kravtsov, V.E. [L.D. Landau Institute for Theoretical Physics, Kosygin st. 2, Moscow 119334 (Russian Federation); Abdus Salam International Center for Theoretical Physics, Trieste (Italy); Cuevas, E. [Departamento de Fisica, Universidad de Murcia, E-30071 Murcia (Spain)

2010-07-15

444

Strong correlation induced charge localization in antiferromagnets  

PubMed Central

The fate of a hole injected in an antiferromagnet is an outstanding issue of strongly correlated physics. It provides important insights into doped Mott insulators closely related to high-temperature superconductivity. Here, we report a systematic numerical study of t-J ladder systems based on the density matrix renormalization group. It reveals a surprising result for the single hole's motion in an otherwise well-understood undoped system. Specifically, we find that the common belief of quasiparticle picture is invalidated by the self-localization of the doped hole. In contrast to Anderson localization caused by disorders, the charge localization discovered here is an entirely new phenomenon purely of strong correlation origin. It results from destructive quantum interference of novel signs picked up by the hole, and since the same effect is of a generic feature of doped Mott physics, our findings unveil a new paradigm which may go beyond the single hole doped system.

Zhu, Zheng; Jiang, Hong-Chen; Qi, Yang; Tian, Chushun; Weng, Zheng-Yu

2013-01-01

445

Localization and percolation in random elastic networks  

NASA Astrophysics Data System (ADS)

We consider a minimal model for a disordered phonon system that shows rich behavior in the localization properties of the phonons. We use a percolation analysis to argue for a localization/delocalization transition of the phonon modes and predict the speed of sound in the delocalized region, with comparison to numerics. We show that in contrast to the behavior in electronic systems (cf. Anderson localization), the transition exists for arbitrarily large disorder, albeit with an exponentially small critical frequency. The structure of the modes reflects a divergent percolation length that arises from the disorder in the springs without being explicitly present in the definition of our model. We calculate the critical frequency as a function of density and test the prediction numerically using a recursive Green function method. We further explore the existence of delocalized states in the two-dimensional version of this model.

Krich, Jacob; Amir, Ariel; Vitelli, Vincenzo; Oreg, Yuval; Imry, Yoseph

2013-03-01

446

Entanglement Entropy in a One-Dimensional Disordered Interacting System: The Role of Localization  

NASA Astrophysics Data System (ADS)

The properties of the entanglement entropy (EE) in one-dimensional disordered interacting systems are studied. Anderson localization leaves a clear signature on the average EE, as it saturates on the length scale exceeding the localization length. This is verified by numerically calculating the EE for an ensemble of disordered realizations using the density matrix renormalization group method. A heuristic expression describing the dependence of the EE on the localization length, which takes into account finite-size effects, is proposed. This is used to extract the localization length as a function of the interaction strength. The localization length dependence on the interaction fits nicely with the expectations.

Berkovits, Richard

2012-04-01

447

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

448

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

449

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.