Memory effects on the statistics of fragmentation

We investigate through extensive molecular dynamics simulations the fragmentation process of two-dimensional Lennard-Jones systems. After thermalization, the fragmentation is initiated by a sudden increment to the radial component of the particles' velocities. We study the effect of temperature of the thermalized system as well as the influence of the impact energy of the ``explosion'' event on the statistics of mass fragments. Our results indicate that the cumulative distribution of fragments follows the scaling ansatz $F(m)\propto m^{-\alpha}\exp{[-(m/m_0)^\gamma]}$, where $m$ is the mass, $m_0$ and $\gamma$ are cutoff parameters, and $\alpha$ is a scaling exponent that is dependent on the temperature. More precisely, we show clear evidence that there is a characteristic scaling exponent $\alpha$ for each macroscopic phase of the thermalized system, i.e., that the non-universal behavior of the fragmentation process is dictated by the state of the system before it breaks down.Comment: 5 pages, 8 figure

Localization properties of a tight-binding electronic model on the Apollonian network

An investigation on the properties of electronic states of a tight-binding Hamiltonian on the Apollonian network is presented. This structure, which is defined based on the Apollonian packing problem, has been explored both as a complex network, and as a substrate, on the top of which physical models can defined. The Schrodinger equation of the model, which includes only nearest neighbor interactions, is written in a matrix formulation. In the uniform case, the resulting Hamiltonian is proportional to the adjacency matrix of the Apollonian network. The characterization of the electronic eigenstates is based on the properties of the spectrum, which is characterized by a very large degeneracy. The $2\pi /3$ rotation symmetry of the network and large number of equivalent sites are reflected in all eigenstates, which are classified according to their parity. Extended and localized states are identified by evaluating the participation rate. Results for other two non-uniform models on the Apollonian network are also presented. In one case, interaction is considered to be dependent of the node degree, while in the other one, random on-site energies are considered.Comment: 7pages, 7 figure

A better physical environment in the workplace means higher well-being? A study with healthcare professionals

Physical working conditions have potential effects on health, and play an important role in quality of life, and job satisfaction, yet most studies on the direct or indirect consequences of physical environmental conditions on healthcare professionals’ focus on outcomes such as performance, efficiency, and error. The objective of this study was to analyze the effects of the physical environment quality of healthcare settings on professionals’ wellbeing. The sample comprised 148 healthcare professionals working in inpatient or outpatient care units from four different hospitals. Two independent variables were used: Objective environmental quality (high/low) and Type of care unit (inpatient/outpatient); and three well-being indicators were analyzed: Job satisfaction, Perception of the care unit as close to an ideal care unit, and Subjective stress. Results show that healthcare professionals working in hospitals with better physical conditions feel more satisfied with their job, and perceive the care unit as closer to the ideal. Stress levels were not affected by physical environment quality or the type of care unit

Immune complex induced arthritis in rats: role of lipid mediators on cell infiltration

We investigated the participation of lipid mediators in an experimental immune complex (IC) arthritis model in rats. The animals were subjected to intraarticular injection of anti-bovine sertLm albumin (BSA) IgG antibodies followed by i.v. injection of BSA. Histopathological analysis of the synovial membranes disclosed infiltration of polymorphonuclear (PMN) cells and vascular congestion. Slight increase in vascular permeability, measured by Evans blue dye extravasation into the joints, was detected after 3 h of arthritis. Cellular influx into the articular cavities was most evident at the sixth hour of arthritis with predominance of PMN. Pretreatment with either indomethacin, a cyclooxygenase inhibitor, or L-660,711, a peptido-leukotriene antagonist, did not inhibit cell infiltration, whereas pretreatment with either L-663,536, a 5-lipoxygenase inhibitor, or L-655,240, a thromboxane antagonist, significantly inhibited the phenomenon. Pretreatment with WEB 2170, a platelet activating factor (PAF) antagonist, also significantly inhibited cell influx. These results suggest that thromboxane, LTB4 and PAF mediate cell infiltration in this IC arthritis model

Estimativa de propriedades biofísicas no mapeamento de pastagens utilizando espectroscopia de imageamento e dados do sensor EO1-Hyperion.

Much attention has been devoted recently to the matter of pasture degradation and the identification of such areas. The main interests in degraded pastures are related to the fact that the recovery of such areas could be used to increase beef cattle production and thus reduce the need for the establishment of new agricultural fields, lowering deforestation pressure. Another topic of interest related to degraded pastures is the Brazilian National Climate Change Policy and the Low Carbon Agriculture Program (Programa ABC ? Agricultura de Baixo Carbono) which aims to reduce national carbon dioxide emissions. The recovery of degraded pasture is one of the objectives of this program, which increases the amount of carbon stored in the soil, acting as a carbon sink. However, the identification of degraded pastures through the use of remote sensing is still in development. Here we present a method based on the use of hyperespectral classification and images from the EO1-Hyperion hyperspectral sensor in order to map the occurrence of pasture areas among the cerrado region. The method is based on a linear spectral unmixing model that can be linked to vegetation characteristics and was capable of discriminating the signals of natural savanna vegetation from pasture and bare soil. The procedure used was able to map pasture areas in the Brazilian Pantanal region and estimate biophysical parameters associated to non-photosynthetic vegetation (ANPV ? dry matter). As future research, spectral mixture analysis approache similar to the ones obtained from Hyperion will be developed based on different orbital sensors, in order to evaluate pasture areas in larger regions

Desenvolvimento e calibração de uma guia de onda para TDR.

A medicao da umidade do solo e crucial para pesquisa e manejo de irrigacao. Entre os metodos mais recentes de determinacao de umidade esta o da TDR ("time domain reflectometry") que se baseia na correlacao entre a propriedade dieletrica do solo e a sua umidade. A obtencao do perfil de umidade do solo requer a utilizaco de um grande numero de guias de onda, cujo custo ainda e elevado. Por outro lado, as curvas de calibracao relacionando umidade com constante dieletrica do solo foram desenvolvidas para solos de paises temperados. Os objetivos desse trabalho foram construir uma guia de onda com materiais facilmente encontrados no mercado nacional e calibra-la para solos tropicais. As curvas de calibracao para areia quartzosa e latossolo vermelho escuro sao distintas e diferentes dos modelos apresentados na literatura. A modificacao de um modelo matematico fisicamente embasado permitiu a geracao de curvas de calibracao com bom ajuste, porem independentes para cada tipo de solo