447 research outputs found

    Novel Quenched Disorder Fixed Point in a Two-Temperature Lattice Gas

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    We investigate the effects of quenched randomness on the universal properties of a two-temperature lattice gas. The disorder modifies the dynamical transition rates of the system in an anisotropic fashion, giving rise to a new fixed point. We determine the associated scaling form of the structure factor, quoting critical exponents to two-loop order in an expansion around the upper critical dimension dc=7_c=7. The close relationship with another quenched disorder fixed point, discovered recently in this model, is discussed.Comment: 11 pages, no figures, RevTe

    On The Discriminative Control Of Concurrent Responses: The Relations Among Response Frequency, Latency, And Topography In Auditory Generalization 1

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    Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/96671/1/jeab.1962.5-487.pd

    Structure of wavefunctions in (1+2)-body random matrix ensembles

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    Abstrtact: Random matrix ensembles defined by a mean-field one-body plus a chaos generating random two-body interaction (called embedded ensembles of (1+2)-body interactions) predict for wavefunctions, in the chaotic domain, an essentially one parameter Gaussian forms for the energy dependence of the number of principal components NPC and the localization length {\boldmath l}_H (defined by information entropy), which are two important measures of chaos in finite interacting many particle systems. Numerical embedded ensemble calculations and nuclear shell model results, for NPC and {\boldmath l}_H, are compared with the theory. These analysis clearly point out that for realistic finite interacting many particle systems, in the chaotic domain, wavefunction structure is given by (1+2)-body embedded random matrix ensembles.Comment: 20 pages, 3 figures (1a-c, 2a-b, 3a-c), prepared for the invited talk given in the international conference on `Perspectives in Theoretical Physics', held at Physical Research Laboratory, Ahmedabad during January 8-12, 200

    Review of the k-Body Embedded Ensembles of Gaussian Random Matrices

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    The embedded ensembles were introduced by Mon and French as physically more plausible stochastic models of many--body systems governed by one--and two--body interactions than provided by standard random--matrix theory. We review several approaches aimed at determining the spectral density, the spectral fluctuation properties, and the ergodic properties of these ensembles: moments methods, numerical simulations, the replica trick, the eigenvector decomposition of the matrix of second moments and supersymmetry, the binary correlation approximation, and the study of correlations between matrix elements.Comment: Final version. 29 pages, 4 ps figures, uses iopart.st

    Hirota's virtual multi-soliton solutions of N=2 supersymmetric Korteweg-de Vries equations

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    We prove that Mathieu's N=2 supersymmetric Korteweg-de Vries equations with a=1 or a=4 admit Hirota's n-supersoliton solutions, whose nonlinear interaction does not produce any phase shifts. For initial profiles that can not be distinguished from a one-soliton solution at times t<<0, we reveal the possibility of a spontaneous decay and, within a finite time, transformation into a solitonic solution with a different wave number. This paradoxal effect is realized by the completely integrable N=2 super-KdV systems, whenever the initial soliton is loaded with other solitons that are virtual and become manifest through the tau-function as the time grows. Key words and phrases: Hirota's solitons, N=2 supersymmetric KdV, Krasil'shchik-Kersten system, phase shift, spontaneous decay.Comment: Proc. 5th International Workshop `Nonlinear Physics: Theory and Experiment' (June 12-21, 2008; Gallipoli, Italy), 11 page

    Top-down control is not lost in the attentional blink: evidence from intact endogenous cuing.

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    The attentional blink (AB) refers to the finding that performance on the second of two targets (T1 and T2) is impaired when the targets are presented at a target onset asynchrony (TOA) of less than 500 ms. One account of the AB assumes that the processing load of T1 leads to a loss of top-down control over stimulus selection. The present study tested this account by examining whether an endogenous spatial cue that indicates the location of a following T2 can facilitate T2 report even when the cue and T2 occur within the time window of the AB. Results from three experiments showed that endogenous cuing had a significant effect on T2 report, both during and outside of the AB; this cuing effect was modulated by both the cue-target onset asynchrony and by cue validity, while it was invariant to the AB. These results suggest that top-down control over target selection is not lost during the AB. © 2007 Springer-Verlag

    Role of the Subunits Interactions in the Conformational Transitions in Adult Human Hemoglobin: an Explicit Solvent Molecular Dynamics Study

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    Hemoglobin exhibits allosteric structural changes upon ligand binding due to the dynamic interactions between the ligand binding sites, the amino acids residues and some other solutes present under physiological conditions. In the present study, the dynamical and quaternary structural changes occurring in two unligated (deoxy-) T structures, and two fully ligated (oxy-) R, R2 structures of adult human hemoglobin were investigated with molecular dynamics. It is shown that, in the sub-microsecond time scale, there is no marked difference in the global dynamics of the amino acids residues in both the oxy- and the deoxy- forms of the individual structures. In addition, the R, R2 are relatively stable and do not present quaternary conformational changes within the time scale of our simulations while the T structure is dynamically more flexible and exhibited the T\rightarrow R quaternary conformational transition, which is propagated by the relative rotation of the residues at the {\alpha}1{\beta}2 and {\alpha}2{\beta}1 interface.Comment: Reprinted (adapted) with permission from J. Phys. Chem. B DOI:10.1021/jp3022908. Copyright (2012) American Chemical Societ

    Large-scale genome-wide association studies and meta-analyses of longitudinal change in adult lung function.

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    BACKGROUND: Genome-wide association studies (GWAS) have identified numerous loci influencing cross-sectional lung function, but less is known about genes influencing longitudinal change in lung function. METHODS: We performed GWAS of the rate of change in forced expiratory volume in the first second (FEV1) in 14 longitudinal, population-based cohort studies comprising 27,249 adults of European ancestry using linear mixed effects model and combined cohort-specific results using fixed effect meta-analysis to identify novel genetic loci associated with longitudinal change in lung function. Gene expression analyses were subsequently performed for identified genetic loci. As a secondary aim, we estimated the mean rate of decline in FEV1 by smoking pattern, irrespective of genotypes, across these 14 studies using meta-analysis. RESULTS: The overall meta-analysis produced suggestive evidence for association at the novel IL16/STARD5/TMC3 locus on chromosome 15 (P  =  5.71 × 10(-7)). In addition, meta-analysis using the five cohorts with ≥3 FEV1 measurements per participant identified the novel ME3 locus on chromosome 11 (P  =  2.18 × 10(-8)) at genome-wide significance. Neither locus was associated with FEV1 decline in two additional cohort studies. We confirmed gene expression of IL16, STARD5, and ME3 in multiple lung tissues. Publicly available microarray data confirmed differential expression of all three genes in lung samples from COPD patients compared with controls. Irrespective of genotypes, the combined estimate for FEV1 decline was 26.9, 29.2 and 35.7 mL/year in never, former, and persistent smokers, respectively. CONCLUSIONS: In this large-scale GWAS, we identified two novel genetic loci in association with the rate of change in FEV1 that harbor candidate genes with biologically plausible functional links to lung function
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