The low-density/high-density liquid phase transition for model globular proteins

The effect of molecule size (excluded volume) and the range of interaction on the surface tension, phase diagram and nucleation properties of a model globular protein is investigated using a combinations of Monte Carlo simulations and finite temperature classical Density Functional Theory calculations. We use a parametrized potential that can vary smoothly from the standard Lennard-Jones interaction characteristic of simple fluids, to the ten Wolde-Frenkel model for the effective interaction of globular proteins in solution. We find that the large excluded volume characteristic of large macromolecules such as proteins is the dominant effect in determining the liquid-vapor surface tension and nucleation properties. The variation of the range of the potential only appears important in the case of small excluded volumes such as for simple fluids. The DFT calculations are then used to study homogeneous nucleation of the high-density phase from the low-density phase including the nucleation barriers, nucleation pathways and the rate. It is found that the nucleation barriers are typically only a few $k_{B}T$ and that the nucleation rates substantially higher than would be predicted by Classical Nucleation Theory.Comment: To appear in Langmui

Colonização e neocolonização da gestão de recursos humanos no Brasil (1950-2010)

Human resource management, as a practical field of business administration and as a teaching and research area, has developed vigorously in Brazil. The objective of this critical essay is to present an historical analysis of this evolution over the last 60 years. To do so we characterize and analyze two periods: 1950-1980, which we call colonization; and 1980-2010, which we call neo-colonization. For each period we present the political and economic context, the changes that occurred in human resource management and the corresponding discourse. Our analysis adopts the perspective of post-colonialism, a rising tide in research in organizational studies, and introduces and uses the perspective of tropicalism, a genuinely local approach, which is derived from the cultural movements of the 1960s. We argue that human resource management developed in Brazil from a colonization movement that came from abroad. This movement, which involved both colonizers and colonized, comprised asymmetries in terms of power, but also included interdependence and re-creations.A Gestão de Recursos Humanos (GRH), como campo prático da Administração de Empresas e como área de ensino e pesquisa, desenvolveu-se vigorosamente no Brasil. Este ensaio crítico tem como objetivo apresentar uma análise histórica dessa evolução nos últimos 60 anos. Para isso, caracterizamos e analisamos dois períodos: 19501980, o qual denominamos colonização; e 1980-2010, o qual denominamos neocolonização. Para cada período, apresentamos o contexto político e econômico, as mudanças ocorridas na GRH e o discurso correspondente. Nossa análise adota a perspectiva do pós-colonialismo, uma corrente de pesquisa ascendente em Estudos Organizacionais, e introduz e utiliza a perspectiva do tropicalismo, uma abordagem genuinamente local, derivada dos movimentos culturais dos anos 1960. Nós argumentamos que a GRH desenvolveu-se no Brasil a partir de um movimento de colonização oriundo do estrangeiro. Tal movimento, envolvendo colonizadores e colonizados, compreendeu assimetrias em termos de poder, porém incluiu também interdependências e recriações.La gestión de Recursos Humanos, como campo práctico de la Administración de Empresas, y como área de enseñanza e investigación, se ha desarrollado vigorosamente en el Brasil. Este ensayo crítico tiene como objetivo presentar un análisis histórico de esta evolución en los últimos 60 años. Para eso, caracterizamos y analizamos dos períodos: 1950-1980, el cual denominamos de colonización; y 1980-2010, al que llamamos de neocolonización. Para cada período, nosotros presentamos un contexto político y económico, los cambios ocurridos en la Gestión de los Recursos Humanos, y el discurso correspondiente. Nuestro análisis adopta la perspectiva del Postcolonialismo, una cadena de investigación ascendente en Estudios Organizacionales, e introduce y utiliza la perspectiva del Tropicalismo, un abordaje genuinamente local, derivado de los movimientos culturales de los años 1960. Nosotros argumentamos que la GRH se ha desarrollado en el Brasil a partir de un movimiento de colonización, oriundo del extranjero. Tal movimiento, envolviendo colonizadores y colonizados, comprendió asimetrías en termos de poder, pero incluyó también interdependencias y recreaciones

Electron beam-induced electrostatic charging causes spectral changes of an insulating electrochromic material

Electrostatic charging of electrically insulating samples upon electron irradiation plays a large role in the analysis and processing of materials in biosciences and the semiconductor industry. We have analyzed spectral changes of purple membranes (PMs) containing bacteriorhodopsin, an electrochromic biological material, upon irradiation with electrons at an acceleration voltage of 30kV. We observed a bathochromic shift in the UV/VIS spectrum of PM films, due to internal electric fields generated by charges injected into the films. The experiments demonstrate that spectroscopic changes, accompanying electron beam-induced charge injection into electrochromic materials, enable quantitative analysis of electrostatic charging of insulators upon electron irradiation by optical spectroscopy

Towards optimum Boersch phase contrast electron cryo-microscopy of biological specimens

Extended abstract of a paper presented at Microscopy and Microanalysis 2012 in Phoenix, Arizona, USA, July 29 – August 2, 2012.</jats:p