Comparação da temperatura do ar obtida por estação meteorológica convencional e automática.

Este trabalho teve como objetivos comparar os dados da temperatura do ar (temperatura média e extrema), obtidos em uma Estação Meteorológica Convencional com os de uma Estação Meteorológica Automática, e avaliar as estimativas da temperatura média diária do ar por diferentes métodos. As estações meteorológicas estavam localizadas na Estação Agroclimatológica de Pelotas, Capão do Leão (31º52? S, 52º21? W e 13,2 m), Rio Grande do Sul, Brasil. A série de cada elemento foi obtida simultaneamente na Estação Automática e na Estação Convencional durante o período de 22/12/2005 a 21/12/2006. Existe alta equivalência para as medidas das temperaturas extremas e das estimativas das temperaturas médias entre as Estações Meteorológicas Convencional e Automática, independente do método utilizado para o cálculo da temperatura média do ar. O termohigrógrafo mede, com alta precisão, as temperaturas extremas do ar. Verificam-se pequenas diferenças nos horários de ocorrência das temperaturas mínimas e máximas entre as Estações Meteorológicas Convencional e Automática. A análise dos dados indica que a substituição da Estação Meteorológica Convencional pela Estação Meteorológicas Automática, na região Sul do Rio Grande do Sul, não acarreta mudanças significativas na série de dados de temperatura do ar

Elastic Constants of Quantum Solids by Path Integral Simulations

Two methods are proposed to evaluate the second-order elastic constants of quantum mechanically treated solids. One method is based on path-integral simulations in the (NVT) ensemble using an estimator for elastic constants. The other method is based on simulations in the (NpT) ensemble exploiting the relationship between strain fluctuations and elastic constants. The strengths and weaknesses of the methods are discussed thoroughly. We show how one can reduce statistical and systematic errors associated with so-called primitive estimators. The methods are then applied to solid argon at atmospheric pressures and solid helium 3 (hcp, fcc, and bcc) under varying pressures. Good agreement with available experimental data on elastic constants is found for helium 3. Predictions are made for the thermal expectation value of the kinetic energy of solid helium 3.Comment: 9 pages doublecolumn, 6 figures, submitted to PR

Molecular Dynamics Simulations

A tutorial introduction to the technique of Molecular Dynamics (MD) is given, and some characteristic examples of applications are described. The purpose and scope of these simulations and the relation to other simulation methods is discussed, and the basic MD algorithms are described. The sampling of intensive variables (temperature T, pressure p) in runs carried out in the microcanonical (NVE) ensemble (N= particle number, V = volume, E = energy) is discussed, as well as the realization of other ensembles (e.g. the NVT ensemble). For a typical application example, molten SiO2, the estimation of various transport coefficients (self-diffusion constants, viscosity, thermal conductivity) is discussed. As an example of Non-Equilibrium Molecular Dynamics (NEMD), a study of a glass-forming polymer melt under shear is mentioned.Comment: 38 pages, 11 figures, to appear in J. Phys.: Condens. Matte

Does type of hospital ownership influence physicians' daily work schedules? An observational real-time study in German hospital departments

Background: During the last two decades the German hospital sector has been engaged in a constant process of transformation. One obvious sign of this is the growing amount of hospital privatization. To date, most research studies have focused on the effects of privatization regarding financial outcomes and quality of care, leaving important organizational issues unexplored. Yet little attention has been devoted to the effects of privatization on physicians' working routines. The aim of this observational real-time study is to deliver exact data about physicians' work at hospitals of different ownership. By analysing working hours, further impacts of hospital privatization can be assessed and areas of improvement identified. Methods: Observations were made by shadowing 100 physicians working in private, for-profit or non-profit as well as public hospital departments individually during whole weekday shifts in urban German settings. A total of 300 days of observations were conducted. All working activities were recorded, accurate to the second, by using a mobile personal computer. Results: Results have shown significant differences in physicians' working activities, depending on hospital ownership, concerning working hours and time spent on direct and indirect patient care. Conclusion: This is the first real-time analysis on differences in work activities depending on hospital ownership. The study provides an objective insight into physicians' daily work routines at hospitals of different ownership, with additional information on effects of hospital privatization