Control of conditional pattern with polarization entanglement

Conditional interference patterns can be obtained with twin photons from spontaneous parametric down-conversion and the phase of the pattern can be controlled by the relative transverse position of the signal and idler detectors. Using a configuration that produces entangled photons in both polarization and transverse momentum we report on the control of the conditional patterns by acting on the polarization degree of freedom.Comment: Submitted for publication in Optics Communication

Fitting isochrones to open cluster photometric data III. Estimating metallicities from UBV photometry

The metallicity is a critical parameter that affects the correct determination fundamental characteristics stellar cluster and has important implications in Galactic and Stellar evolution research. Fewer than 10 % of the 2174 currently catalog open clusters have their metallicity determined in the literature. In this work we present a method for estimating the metallicity of open clusters via non-subjective isochrone fitting using the cross-entropy global optimization algorithm applied to UBV photometric data. The free parameters distance, reddening, age, and metallicity simultaneously determined by the fitting method. The fitting procedure uses weights for the observational data based on the estimation of membership likelihood for each star, which considers the observational magnitude limit, the density profile of stars as a function of radius from the center of the cluster, and the density of stars in multi-dimensional magnitude space. We present results of [Fe/H] for nine well-studied open clusters based on 15 distinct UBV data sets. The [Fe/H] values obtained in the ten cases for which spectroscopic determinations were available in the literature agree, indicating that our method provides a good alternative to determining [Fe/H] by using an objective isochrone fitting. Our results show that the typical precision is about 0.1 dex

Activity Recognition based on a Magnitude-Orientation Stream Network

The temporal component of videos provides an important clue for activity recognition, as a number of activities can be reliably recognized based on the motion information. In view of that, this work proposes a novel temporal stream for two-stream convolutional networks based on images computed from the optical flow magnitude and orientation, named Magnitude-Orientation Stream (MOS), to learn the motion in a better and richer manner. Our method applies simple nonlinear transformations on the vertical and horizontal components of the optical flow to generate input images for the temporal stream. Experimental results, carried on two well-known datasets (HMDB51 and UCF101), demonstrate that using our proposed temporal stream as input to existing neural network architectures can improve their performance for activity recognition. Results demonstrate that our temporal stream provides complementary information able to improve the classical two-stream methods, indicating the suitability of our approach to be used as a temporal video representation.Comment: 8 pages, SIBGRAPI 201

Experimental methods on the determination of the mechanical properties of concrete at high temperatures

Até ao momento não existem ainda procedimentos padrão para ensaios a altas temperaturas no betão, pelo que têm sido realizados ensaios a temperaturas elevadas adaptados de ensaios à temperatura ambiente. Os ensaios têm-se dividido entre ensaios a altas temperaturas e residuais após aquecimento e arrefecimento. O primeiro procedimento é mais adequado para a determinação das propriedades mecânicas do betão durante um incêndio enquanto o segundo procedimento é usado para determinar a resistência residual do betão após incêndio. Nesta comunicação apresentam-se os resultados de ensaios realizados por diferentes autores para a determinação das propriedades mecânicas residuais do betão após aquecimento e arrefecimento. Os resultados apresentados dizem respeito a resistências residuais à compressão, tração e flexão e módulo de elasticidade. Os métodos de ensaio aplicados são devidamente descritos e os resultados obtidos são objeto de análises comparativas.ABSTRACT: So far there are no standard procedures for testing concrete at high temperatures which have been conducted according to the ones at ambient temperature. The tests have been divided between tests at high temperatures and residual after heating and cooling. The first procedure is appropriate for determining the mechanical properties of concrete during fire while the second is used to determine the residual mechanical properties of concrete after fire. In this paper are presented the results of tests carried out by different authors for assessing the residual mechanical properties of concrete after heating and cooling. The results presented are respecting to residual compressive, tensile and flexural strength and elasticity modulus. The test methods are described and results obtained are compared

Caracterização dos sedimentos da Lagoa da Apúlia (PNLN), Esposende, NW de Portugal

A Lagoa da Apúlia é um espaço natural enquadrado no Parque Natural Litoral do Norte (PNLN). Tem existido interesse, por parte do PNLN, em reabilitar este ambiente classificado como zona de proteção parcial do tipo 1 e com o seu Habitat classificado como prioritário pela Diretiva Habitats. O objetivo do estudo é compreender os processos que controlam o enchimento da lagoa e, para tal, aproveitou-se uma intervenção levada a cabo pelo PNLN, para amostrar o material proveniente até 4 metros profundidade. Foram recolhidas 10 amostras provenientes de 3 perfis. As amostras foram sujeitas ao seguinte tratamento laboratorial: secagem em estufa a temperatura inferior a 40 °C; quartilhamento; análise dimensional obtida por crivação no RoTap durante 15 minutos, segundo uma escala dimensional com intervalos iguais a √2, e por Sedigraph, para as partículas inferiores a 62 μm. Para os cálculos granulométricos e dos parâmetros estatísticos foi usado o programa SEDMAC/SEDPC (Henriques, 2003). Cada fração retida nos crivos foi observada à lupa binocular, tendo sido registada qualitativamente a composição, a sua abundância relativa, a forma e o desgaste dos grãos. O enchimento da Lagoa da Apúlia, até 4 metros de profundidade, é genericamente constituído por sedimentos areno-lodosos, variando de areão, 15 % nas camadas mais profundas, a areia, 30 % nas intermédias, contendo uma fração fina abundante, até cerca de 60 % de limo e argila nas camadas do topo. Os grãos são, na sua maioria, de quartzo, biotite e moscovite, de modo geral, com forma esférica a subdiscoide e apresentando-se angulosos a subangulosos. No estudo à lupa existiu uma especial atenção para a pesquisa de organismos (ou seus restos) de origem marinha e terrestre, que se verificou serem inexistentes, no caso dos de origem marinha, aparecendo apenas restos de origem vegetal. Os resultados indicam que os sedimentos até à profundidade amostrada, são de origem próxima, cujo transporte ocorreu com variações de energia, atingindo condições para a deposição gravítica da fração fina de lodo. Conclui-se que a Lagoa da Apúlia tem sido dominada por assoreamento, por ação de transporte fluvial. A condição lacustre com interesse a ser preservada em termos de Habitat, embora historicamente instalada, está ameaçada, sendo a colmatação da lagoa a tendência dominante atualmente. Os estudos realizados na região por Granja, et al. (2010), indicam que a área esteve sujeita a três fases distintas, sendo a primeira correspondente a um ambiente do tipo estuarino ou fluvial, a segunda a um ambiente de lagoa e a terceira a um ambiente eólico, terminando com a pedogénese deste. Neste contexto, a Lagoa da Apúlia pode ser usada como testemunho da evolução ambiental da zona litoral norte.info:eu-repo/semantics/publishedVersio

Conservation of Orbital Angular Momentum in Stimulated Down-Conversion

We report on an experiment demonstrating the conservation of orbital angular momentum in stimulated down-conversion. The orbital angular momentum is not transferred to the individual beams of the spontaneous down-conversion, but it is conserved when twin photons are taken individually. We observe the conservation law for an individual beam of the down-conversion through cavity-free stimulated emission.Comment: Submitted for publication in Phys. Rev. Let

Micro-firms way to succeed: How owners manage people

This study explores the configurations of people management practices in micro-firms and their relation with entrepreneurial orientation and firm performance in a four-year window. Based on the ability-, motivation- and opportunity-focused practices framework, we identify configurations of HRM practices used in micro-firms and, in conjugation with entrepreneurial orientation, how they affect employee growth and net income. We analyzed data collected from 114 micro-firm owners combined with firm objective performance measures using Multiple Correspondence Analysis and Cluster Analysis. Results show a taxonomy of three configurations of HRM practices associated with different entrepreneurial orientation strategic postures in micro-firms: “Financial centric HRM practices”, “Operations centric HRM practices”, and “People centric HRM practices”. We assume that configurational methods can help uncover the complexity of the interplay between HRM practices and strategic postures on micro-firm performance. This study contributes to the literature in micro-firms by revealing effective people-related managerial practices on performance.info:eu-repo/semantics/publishedVersio

Structural fluctuations and quantum transport through DNA molecular wires: a combined molecular dynamics and model Hamiltonian approach

Charge transport through a short DNA oligomer (Dickerson dodecamer) in presence of structural fluctuations is investigated using a hybrid computational methodology based on a combination of quantum mechanical electronic structure calculations and classical molecular dynamics simulations with a model Hamiltonian approach. Based on a fragment orbital description, the DNA electronic structure can be coarse-grained in a very efficient way. The influence of dynamical fluctuations arising either from the solvent fluctuations or from base-pair vibrational modes can be taken into account in a straightforward way through time series of the effective DNA electronic parameters, evaluated at snapshots along the MD trajectory. We show that charge transport can be promoted through the coupling to solvent fluctuations, which gate the onsite energies along the DNA wire