Electric Deflection of Rotating Molecules

We provide a theory of the deflection of polar and non-polar rotating molecules by inhomogeneous static electric field. Rainbow-like features in the angular distribution of the scattered molecules are analyzed in detail. Furthermore, we demonstrate that one may efficiently control the deflection process with the help of short and strong femtosecond laser pulses. In particular the deflection process may by turned-off by a proper excitation, and the angular dispersion of the deflected molecules can be substantially reduced. We study the problem both classically and quantum mechanically, taking into account the effects of strong deflecting field on the molecular rotations. In both treatments we arrive at the same conclusions. The suggested control scheme paves the way for many applications involving molecular focusing, guiding, and trapping by inhomogeneous fields

Effective pair potentials for spherical nanoparticles

An effective description for spherical nanoparticles in a fluid of point particles is presented. The points inside the nanoparticles and the point particles are assumed to interact via spherically symmetric additive pair potentials, while the distribution of points inside the nanoparticles is taken to be spherically symmetric and smooth. The resulting effective pair interactions between a nanoparticle and a point particle, as well as between two nanoparticles, are then given by spherically symmetric potentials. If overlap between particles is allowed, the effective potential generally has non-analytic points, but for each effective potential the expressions for different overlapping cases can be written in terms of one analytic auxiliary potential. Effective potentials for hollow nanoparticles (appropriate e.g. for buckyballs) are also considered, and shown to be related to those for solid nanoparticles. Finally, explicit expressions are given for the effective potentials derived from basic pair potentials of power law and exponential form, as well as from the commonly used London-Van der Waals, Morse, Buckingham, and Lennard-Jones potential. The applicability of the latter is demonstrated by comparison with an atomic description of nanoparticles with an internal face centered cubic structure.Comment: 27 pages, 12 figures. Unified description of overlapping and nonoverlapping particles added, as well as a comparison with an idealized atomic descriptio

Avaliação da Sustentabilidade de Programas Municipais de Coleta Seletiva e Organizações de Catadores de Materiais Recicláveis do Espírito Santo

Os municípios brasileiros enfrentam diversas dificuldades para realizar a coleta seletiva, enquanto as organizações de catadores de materiais recicláveis necessitam vencer diversas disfunções para se tornarem competitivas no mercado. Para superar tais desafios e atender às exigências da Política Nacional de Resíduos Sólidos é necessário conhecer os elementos que interferem no desempenho dos programas de coleta seletiva e organizações de catadores. Nesse sentido, este estudo teve como principal objetivo avaliar os programas de coleta seletiva e organizações de catadores de municípios do estado do Espírito Santo em relação à sustentabilidade e propor estratégia metodológica para delineamento de ações necessárias aos Planos Municipais de Gestão Integrada de Resíduos Sólidos desses municípios. Para tal, foram selecionados 24 municípios, avaliados por seus programas de coleta seletiva, e 23 organizações de catadores sobre os quais foram aplicados questionários para obtenção dos dados necessários para o cálculo dos indicadores e dos índices de sustentabilidade. Além disso, as ações dos Planos Municipais de Gestão Integrada de Resíduos Sólidos foram elencadas e relacionadas com os indicadores de forma a verificar quais ações já eram contempladas pelos planos para não haver repetições ao propor novas ações. A partir do resultado da análise dos indicadores e da verificação das ações dos planos de resíduos, foi apresentada uma proposta metodológica para sugerir ações em complementação ao que foi verificado nos planos. As ações propostas também foram hierarquizadas em graus de urgência temporal para sua implementação, utilizando como critério o peso de cada um dos indicadores. Os indicadores analisados apresentaram resultados, em geral, insatisfatórios em relação à sustentabilidade. A média dos índices de sustentabilidade dos programas de coleta seletiva foi 0,44 (desfavorável em relação à sustentabilidade) com coeficiente de variação de 0,35. Já a média dos índices de sustentabilidade das organizações de catadores foi 0,52 (favorável em relação à sustentabilidade) com coeficiente de variação de 0,12. Ainda foi verificado que as ações descritas nos planos de resíduos tinham caráter subjetivo e eram abrangentes, interferindo no desempenho do município em relação à sustentabilidade, necessitando de complementação. Dessa forma, foi possível propor ações relacionadas ao aprimoramento da coleta seletiva, controle de dados relativos à coleta seletiva e a triagem, educação e divulgação da coleta seletiva, condições de trabalho, saúde e segurança na coleta e no galpão de triagem, estruturação, regularização e autogestão das organizações. Espera-se que, com a implementação das ações propostas, a coleta seletiva e as organizações de catadores se tornem sustentáveis ao longo dos anos. Conforme sugerem os dados obtidos, o delineamento das ações tem grande potencial para aplicação no monitoramento e no desenvolvimento de programas de coleta seletiva e organizações de catadores em direção à sustentabilidade. Dessa forma, essas ações podem proporcionar benefícios à gestão de resíduos sólidos no contexto geral

Onsager-Machlup theory and work fluctuation theorem for a harmonically driven Brownian particle

We extend Tooru-Cohen analysis for nonequilirium steady state(NSS) of a Brownian particle to nonequilibrium oscillatory state (NOS) of Brownian particle by considering time dependent external drive protocol. We consider an unbounded charged Brownian particle in the presence of an oscillating electric field and prove work fluctuation theorem, which is valid for any initial distribution and at all times. For harmonically bounded and constantly dragged Brownian particle considered by Tooru and Cohen, work fluctuation theorem is valid for any initial condition(also NSS), but only in large time limit. We use Onsager-Machlup Lagrangian with a constraint to obtain frequency dependent work distribution function, and describe entropy production rate and properties of dissipation functions for the present system using Onsager-Machlup functional.Comment: 6 pages, 1 figur

The need for farm forestry

16 pages; includes photographs and drawing. This archival publication may not reflect current scientific knowledge or recommendations. Current information available from the University of Minnesota Extension: https://www.extension.umn.edu

Mode-coupling theory for multiple-time correlation functions of tagged particle densities and dynamical filters designed for glassy systems

The theoretical framework for higher-order correlation functions involving multiple times and multiple points in a classical, many-body system developed by Van Zon and Schofield [Phys. Rev. E 65, 011106 (2002)] is extended here to include tagged particle densities. Such densities have found an intriguing application as proposed measures of dynamical heterogeneities in structural glasses. The theoretical formalism is based upon projection operator techniques which are used to isolate the slow time evolution of dynamical variables by expanding the slowly-evolving component of arbitrary variables in an infinite basis composed of the products of slow variables of the system. The resulting formally exact mode-coupling expressions for multiple-point and multiple-time correlation functions are made tractable by applying the so-called N-ordering method. This theory is used to derive for moderate densities the leading mode coupling expressions for indicators of relaxation type and domain relaxation, which use dynamical filters that lead to multiple-time correlations of a tagged particle density. The mode coupling expressions for higher order correlation functions are also succesfully tested against simulations of a hard sphere fluid at relatively low density.Comment: 15 pages, 2 figure

Comment on ``Lyapunov Exponent of a Many Body System and Its Transport Coefficients''

In a recent Letter, Barnett, Tajima, Nishihara, Ueshima and Furukawa obtained a theoretical expression for the maximum Lyapunov exponent $\lambda_1$ of a dilute gas. They conclude that $\lambda_1$ is proportional to the cube root of the self-diffusion coefficient $D$, independent of the range of the interaction potential. They validate their conjecture with numerical data for a dense one-component plasma, a system with long-range forces. We claim that their result is highly non-generic. We show in the following that it does not apply to a gas of hard spheres, neither in the dilute nor in the dense phase.Comment: 1 page, Revtex - 1 PS Figs - Submitted to Physical Review Letter

Dynamic Modeling and Simulation of a Real World Billiard

Gravitational billiards provide an experimentally accessible arena for testing formulations of nonlinear dynamics. We present a mathematical model that captures the essential dynamics required for describing the motion of a realistic billiard for arbitrary boundaries. Simulations of the model are applied to parabolic, wedge and hyperbolic billiards that are driven sinusoidally. Direct comparisons are made between the model's predictions and previously published experimental data. It is shown that the data can be successfully modeled with a simple set of parameters without an assumption of exotic energy dependence.Comment: 10 pages, 3 figure

Experimental test of the Gallavotti-Cohen fluctuation theorem in turbulent flows

We test the fluctuation theorem from measurements in turbulent flows. We study the time fluctuations of the force acting on an obstacle, and we consider two experimental situations: the case of a von K\'arm\'an swirling flow between counter-rotating disks (VK) and the case of a wind tunnel jet. We first study the symmetries implied by the Gallavotti-Cohen fluctuation theorem (FT) on the probability density distributions of the force fluctuations; we then test the Sinai scaling. We observe that in both experiments the symmetries implied by the FT are well verified, whereas the Sinai scaling is established, as expected, only for long times