Path-integral study of a two-dimensional Lennard-Jones glass

The glass transition in a quantum Lennard-Jones mixture is investigated by constant-volume path-integral simulations. Particles are assumed to be distinguishable, and the strength of quantum effects is varied by changing h from zero (the classical case) to one (corresponding to a highly quantum-mechanical regime). Quantum delocalization and zero point energy drastically reduce the sensitivity of structural and thermodynamic properties to the glass transition. Nevertheless, the glass transition temperature T-g can be determined by analyzing the phase space mobility of path-integral centroids. At constant volume, the T-g of the simulated model increases monotonically with increasing h. Low temperature tunneling centers are identified, and the quantum versus thermal character of each center is analyzed. The relation between these centers and soft quasilocalized harmonic vibrations is investigated. Periodic minimizations of the potential energy with respect to the positions of the particles are performed to determine the inherent structure of classical and quantum glassy samples. The geometries corresponding to these energy minima are found to be qualitatively similar in all cases. Systematic comparisons for ordered and disordered structures, harmonic and anharmonic dynamics, classical and quantum systems show that disorder, anharmonicity, and quantum effects are closely interlinked.

Monte Carlo studies of phase transitions and adsorption : application to n-6 Lennard-Jones, C60 and zeolite systems

The solid-fluid transition properties of the n - 6 Lennard-Jones system are studied by means of extensive free energy calculations. Different values of the parameter n which regulates the steepness of the short-range repulsive interaction are investigated. Furthermore, the free energies of the n < 12 systems are calculated using the n = 12 system as a reference. The method relies on a generalization of the multiple histogram method that combines independent canonical ensemble simulations performed with different Hamiltonians and computes the free energy difference between them. The phase behavior of the fullerene C60 solid is studied by performing NPT simulations using atomistic models which treat each carbon in the molecule as a separate interaction site with additional bond charges. In particular, the transition from an orientationally frozen phase at low temperatures to one where the molecules are freely rotating at higher temperatures is studied as a function of applied pressure. The adsorption of molecular hydrogen in the zeolite NaA is investigated by means of grand-canonical Monte Carlo, in a wide range of temperatures and imposed gas pressures, and results are compared with available experimental data. A potential model is used that comprises three main interactions: van der Waals, Coulomb and induced polarization by the permanent electric field in the zeolite.

Jones Creek S342

The South Carolina Department of Natural Resources provides maps to recreational and state shellfish grounds, available to the public for recreational harvesting or to commercial harvest. This map shows the location of Jones Creek S342 Recreational Shellfish Ground in Georgetown County.

O efeito da t��cnica de inibi����o de Jones nos m��sculos Masseter e temporal nas disfun����es temporomandibulares

Introdu����o: A disfun����o temporomandibular (DTM), de causa muscular, caracteriza-se por uma dor m��sculo-esquel��tica cr��nica, com sinais e sintomas espec��ficos como a presen��a de Trigger Points (TrPs). Objetivo: Avaliar o efeito da T��cnica de Inibi����o de Jones (TIJ) nos m��sculos masseter e temporal em indiv��duos com DTM, e a identifica����o dos sinais e sintomas, a rela����o entre a severidade da DTM, a ansiedade e a qualidade de sono. M��todos: Estudo quasi-experimental, constitu��do por 16 indiv��duos no grupo experimental (GE) e 17 grupo controle (GC). O grau de severidade foi avaliado pelo ��ndice de Helkimo e as altera����es do sono pelo question��rio de Pittsburgh sobre a qualidade do sono. Apenas o GE foi sujeito a uma TIJ nos TrPs latentes dos m��sculos masseter e temporal. Os dois grupos foram avaliados pr��-interven����o (M0), p��s-interven����o (M1) e 3 semanas ap��s (M2), as amplitudes de movimento ativas de abertura, lateralidade direita/esquerda e protus��o da boca bem como a dor (EVA) em repouso e na abertura m��xima. Resultados: Foi poss��vel observar que quanto maior o grau de DTM, maior a frequ��ncia de ansiedade e pior a qualidade do sono. Observou-se um decr��scimo de TrPs, no GE, ap��s a aplica����o da t��cnica, principalmente no masseter. N��o foi poss��vel verificar diferen��as inter-grupos. Contudo, observou-se no GE uma melhoria em todas as amplitudes avaliadas entre o M0 e o M2. Em rela����o �� EVA em repouso e na abertura m��xima, o GE demonstrou diminui����o da dor no M1 e manteve valores inferiores no M2. Conclus��o: Verifica-se uma diminui����o dos TrPs, uma melhoria das amplitudes ativas bem como uma diminui����o da dor ap��s a aplica����o da TIJ no GE. J�� ao longo do tempo, o efeito �� menos expressivo contudo observam-se valores inferiores comparativamente a M0.

Dynamics of the Dow Jones and the NASDAQ stock indexes

The goal of this study is the analysis of the dynamical properties of financial data series from worldwide stock market indices. We analyze the Dow Jones Industrial Average ( ��� DJI) and the NASDAQ Composite ( ��� IXIC) indexes at a daily time horizon. The methods and algorithms that have been explored for description of physical phenomena become an effective background, and even inspiration, for very productive methods used in the analysis of economical data. We start by applying the classical concepts of signal analysis, Fourier transform, and methods of fractional calculus. In a second phase we adopt a pseudo phase plane approach.