Photoassociative ionization of Na inside a storage ring

Motivated by recent interest in low dimensional arrays of atoms, we experimentally investigated the way cold collisional processes are affected by the geometry of the considered atomic sample. More specifically, we studied the case of photoassociative ionization (PAI) both in a storage ring where collision is more unidirectional in character and in a trap with clear undefinition of collision axis. First, creating a ring shaped trap (atomotron) we investigated two-color PAI dependence with intensity and polarization of a probing laser. The intensity dependence of the PAI rate was also measured in a magneto-optical trap presenting equivalent temperature and density conditions. Indeed, the results show that in the ring trap, the value of the PAI rate constant is much lower and does not show evidences of saturation, unlike in the case of the 3D-MOT. Cold atomic collisions in storage ring may represent new possibilities for study.Comment: 5 pages, 5 figures; Accepted by Optics Communicatio

Gestão e políticas públicas em Minas Gerais: cultura e patrimônio cultural

Aborda-se o papel do Estado e dos seus gestores em relação à adoção de políticas de preservação da cultura e do patrimônio cultural em Minas Gerais. O objetivo central é convidar o leitor a refletir sobre as políticas públicas de preservação do patrimônio cultural e o papel do gestor em relação às ações desenvolvidas no Estado de Minas Gerais, nos diferentes municípios que compõe esse estado

The isotopic composition (d15N, d13C) of agricultural wastes and derived composts.

The aim of this study was to measure variations in the isotopic composition (d13C and d15N) during the composting of different agricultural wastes using bench-scale bioreactors. Four different feedstocks of agricultural wastes (Horse bedding manure + legumes residues; Dairy manure + Jatropha mill cake; Dairy manure + sugarcane residues; Dairy manure) were used for aerobic-thermophilic composting. During composting no significant differences were found between the d13C values of the source material and the compost, except for Dairy manure + sugarcane residues. d15N values increased significantly in composts of Horse bedding manure + legumes residues and Dairy manure + Jatropha mill cake. d15N values of composts may be related to NH3 volatilization during the composting process. Isotopic signatures (d13C, d15N) can be used to differentiate composts from different feedstock sources and d15N values may be a quantitative indicator of NH3 volatilization during composting. Use of bench-scale bioreactors is a promising apparatus to study the dynamics of C and N and stable isotopes signatures during composting, but future adjustments regarding sampling methodology are necessary

Food consumption of Rhammatocerus schistocercoides Rehn (Orthoptera: Acrididae) infected by the fungus Metarhizium flavoviride Gams & Rozsypal.

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Description of a Eulerian–Lagrangian Approach for the Modeling of Cooling Water Droplets

The present paper describes a tool developed in-house for the modeling of free-falling water droplet cooling processes. A two-way coupling model is employed to account for the interactions between the droplets and the carrier fluid, following a Eulerian-Lagrangian approach. In addition, a stochastic separated flow technique is employed, involving random sampling of the fluctuating fluid velocity. In physical modeling, two empirical correlations are considered for determining the heat and mass transfer coefficients, with the possibility of accounting for vibrations. The numerical results indicate the preponderance of the interactions between droplet and carrier fluid at various humidity ratios.Fundação para a Ciência e a Tecnologiainfo:eu-repo/semantics/publishedVersio

Avaliação do módulo de elasticidade de betões de elevado desempenho com cinzas volantes

Os betões de elevado desempenho (BED) geralmente recorrem a materiais e a processos de fabrico de custo mais elevado que o dos betões correntes. Este facto tem condicionado a aplicação destes betões a obras especiais, apesar dos benefícios mecânicos e físicos que resultam a longo prazo poderem superar o maior investimento inicial. Nos últimos anos tem-se desenvolvido BED de custo controlado, substituindo-se parte de cimento por cinzas volantes e adoptando-se materiais e procedimentos de fabrico correntes. Neste trabalho, o módulo de elasticidade dos BED desenvolvidos é determinado experimentalmente e comparado com o obtido com formulações regulamentares e aplicando modelos baseados na teoria dos materiais compósitos

Characterization of a Two-way Coupling Approach for the Simulation of Fluid Flows under Cryogenic Conditions

Ice formation at lifting surfaces and engine intakes is a significant issue affecting regular aircraft operation. The icing on a wing’s leading edge perturbs the airflow around the wing, contributing to a decrease in lift and increasing drag. A step towards the understanding of droplet dynamics under cryogenics is made in the present work. An in-house developed tool is used to study the impact of droplet diameter and air humidity ratio in free-falling water droplets’ flow dynamics. The 3D Navier-Stokes equations are solved in a RANS-based two-way coupling model, which considers that the carrier fluid properties are modified by the presence of a dispersed phase, accounting for mass exchange momentum and energy between them. A Lagrangian/Eulerian formulation is employed to model each of the considered phases. The results obtained are compared with a one-way modeling approach and experimental data to infer the interacting phases’ effect in the overall process dynamics. In this way, it is possible to conclude that for high humidity content, this interaction is predominant and, consequently, needs to be taken into consideration. However, for low humidity ratios, the one-way coupling is a sufficient approximation to the experimental data.Fundação para a Ciência e a Tecnologiainfo:eu-repo/semantics/publishedVersio