Influence of structure on the optical limiting properties of nanotubes

We investigate the role of carbon nanotubes structure on their optical limiting properties. Samples of different and well-characterized structural features are studied by optical limiting and pump-probe experiments. The influence of the diameter's size on the nano-object is demonstrated. Indeed, both nucleation and growth of gas bubbles are expected to be sensitive to diameter

Determinants of sedentary behavior, motivation, barriers and strategies to reduce sitting time in older women: a qualitative investigation

Abstract: Sedentary behavior defined as time spent non-exercising seated or reclining posture has been identified has a health risk and associated with frailty and disablement for older adults. Older adults are the most sedentary segment of society. To date no study has investigated the determinants of sedentary behavior in older adults. This study reports a qualitative investigation of the determinants of sedentary behavior, strategies and motivator to reduce sitting time by structured interviews in a group of community dwelling older women (N = 11, age 65 and over). Older women expressed the view that their sedentary behavior is mostly determined by pain which acts both as an incentive to sit and a motivator to stand up, lack of energy in the afternoon, pressure from direct social circle to sit and rest, societal and environmental typecasting that older adult are meant to sit, lack of environmental facilities to allow activity pacing. This qualitative investigation highlighted some factors that older adults consider determinants of their sedentary behavior. Some are identical to those affecting physical activity (self-efficacy, functional limitations, ageist stereotyping) but some appear specific to sedentary behavior (locus of control, pain) and should be further investigated and considered during intervention design. Tailore

Towards a theory of urban sustainability

Este artículo perfila conjuntamente tres ámbitos sociales de la economía, de la política y de la vida cotidiana en un intento de construir una teoría de la sostenibilidad urbana. Se parte de un enfoque holístico que integre el análisis de estos dominios. Se afirma que una correcta comprensión del concepto de sostenibilidad sólo se puede alcanzar si se incorpora la totalidad de tensiones, balances y dinámicas de los tres ámbitos ya señalados. A la vez se reconoce que el deterioro ambiental es el mayor desafío para la consecución de la sostenibilidad.This article draws together the three societal domains of Economy, Politics and Lifeworld in an attempt to construct a theory of urban sustainability. It takes an holistic approach which integrates an analysis devolving on these three domains. The concern with the urban pivots around the transformed role of cities in the transition from industrial to post-industrial society. It asserts that an adequate understanding of the concept of sustainability can only be grasped if the totality of the tensions, balances and dynamics of the three domains outlined above are fully incorporated into the theory. While it concentrates on these three domains it recognises that ecological deterioration, is perhaps the most pressing challenge to sustainability

Existence of the Wigner function with correct marginal distributions along tilted lines on a lattice

In order to determine the Wigner function uniquely, we introduce a new condition which ensures that the Wigner function has correct marginal distributions along tilted lines. For a system in $N$ dimensional Hilbert space, whose "phase space" is a lattice with $N^2$ sites, we get different results depending on whether $N$ is odd or even. Under the new condition, the Wigner function is determined if $N$ is an odd number, but it does not exist if $N$ is even.Comment: 18 page

The Spectrotemporal Filter Mechanism of Auditory Selective Attention

SummaryAlthough we have convincing evidence that attention to auditory stimuli modulates neuronal responses at or before the level of primary auditory cortex (A1), the underlying physiological mechanisms are unknown. We found that attending to rhythmic auditory streams resulted in the entrainment of ongoing oscillatory activity reflecting rhythmic excitability fluctuations in A1. Strikingly, although the rhythm of the entrained oscillations in A1 neuronal ensembles reflected the temporal structure of the attended stream, the phase depended on the attended frequency content. Counter-phase entrainment across differently tuned A1 regions resulted in both the amplification and sharpening of responses at attended time points, in essence acting as a spectrotemporal filter mechanism. Our data suggest that selective attention generates a dynamically evolving model of attended auditory stimulus streams in the form of modulatory subthreshold oscillations across tonotopically organized neuronal ensembles in A1 that enhances the representation of attended stimuli

Wigner Functions on a Lattice

The Wigner functions on the one dimensional lattice are studied. Contrary to the previous claim in literature, Wigner functions exist on the lattice with any number of sites, whether it is even or odd. There are infinitely many solutions satisfying the conditions which reasonable Wigner functions should respect. After presenting a heuristic method to obtain Wigner functions, we give the general form of the solutions. Quantum mechanical expectation values in terms of Wigner functions are also discussed.Comment: 11 pages, no figures, REVTE

A Lifting Relation from Macroscopic Variables to Mesoscopic Variables in Lattice Boltzmann Method: Derivation, Numerical Assessments and Coupling Computations Validation

In this paper, analytic relations between the macroscopic variables and the mesoscopic variables are derived for lattice Boltzmann methods (LBM). The analytic relations are achieved by two different methods for the exchange from velocity fields of finite-type methods to the single particle distribution functions of LBM. The numerical errors of reconstructing the single particle distribution functions and the non-equilibrium distribution function by macroscopic fields are investigated. Results show that their accuracy is better than the existing ones. The proposed reconstruction operator has been used to implement the coupling computations of LBM and macro-numerical methods of FVM. The lid-driven cavity flow is chosen to carry out the coupling computations based on the numerical strategies of domain decomposition methods (DDM). The numerical results show that the proposed lifting relations are accurate and robust

Measurement-induced decoherence and Gaussian smoothing of the Wigner distribution function

We study the problem of measurement-induced decoherence using the phase-space approach employing the Gaussian-smoothed Wigner distribution function. Our investigation is based on the notion that measurement-induced decoherence is represented by the transition from the Wigner distribution to the Gaussian-smoothed Wigner distribution with the widths of the smoothing function identified as measurement errors. We also compare the smoothed Wigner distribution with the corresponding distribution resulting from the classical analysis. The distributions we computed are the phase-space distributions for simple one-dimensional dynamical systems such as a particle in a square-well potential and a particle moving under the influence of a step potential, and the time-frequency distributions for high-harmonic radiation emitted from an atom irradiated by short, intense laser pulses.Comment: Accepted in Annals of Physic

Unstable particles in matter at a finite temperature: the rho and omega mesons

Unstable particles (such as the vector mesons) have an important role to play in low mass dilepton production resulting from heavy ion collisions and this has been a subject of several investigations. Yet subtleties, such as the implications of the generalization of the Breit-Wigner formula for nonzero temperature and density, e.g. the question of collisional broadening, the role of Bose enhancement, etc., the possibility of the kinematic opening (or closing) of decay channels due to environmental effects, the problem of double counting through resonant and direct contributions, are often given insufficient emphasis. The present study attempts to point out these features using the rho and omega mesons as illustrative examples. The difference between the two versions of the Vector Meson Dominance Model in the present context is also presented. Effects of non-zero temperature and density, through vector meson masses and decay widths, on dilepton spectra are studied, for concreteness within the framework of a Walecka-type model, though most of the basic issues highlighted apply to other scenarios as well.Comment: text and figures modifie

Analyzing the Effect of Interview Time and Day on Emergency Medicine Residency Interview Scores

Learning Objectives: To analyze whether interview date or time has an effect on residency interview score for applicants to Emergency Medicine residency programs