2,316 research outputs found

    Slowly Rotating Anisotropic Neutron Stars in General Relativity and Scalar-Tensor Theory

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    Some models (such as the Skyrme model, a low-energy effective field theory for QCD) suggest that the high-density matter prevailing in neutron star interiors may be significantly anisotropic. Anisotropy is known to affect the bulk properties of nonrotating neutron stars in General Relativity. In this paper we study the effects of anisotropy on slowly rotating stars in General Relativity. We also consider one of the most popular extensions of Einstein's theory, namely scalar-tensor theories allowing for spontaneous scalarization (a phase transition similar to spontaneous magnetization in ferromagnetic materials). Anisotropy affects the moment of inertia of neutron stars (a quantity that could potentially be measured in binary pulsar systems) in both theories. We find that the effects of scalarization increase (decrease) when the tangential pressure is bigger (smaller) than the radial pressure, and we present a simple criterion to determine the onset of scalarization by linearizing the scalar-field equation. Our calculations suggest that binary pulsar observations may constrain the degree of anisotropy or even, more optimistically, provide evidence for anisotropy in neutron star cores.Comment: 19 pages, 7 figures, 1 table. Matches version in press in CQG. Fixed small typo

    Avaliação da influência das propriedades de adesivos e da geometria de laminados de fibra de carbono no comportamento de ensaios de arranque

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    O presente trabalho foi desenvolvido para estudar a liga betão, com a técnica de reforço de estruturas NSM executado um programa experimental para avaliar a influência do comprimento de amarração, da profundidade de colocação do laminado, da um adesivo com resistência melhorada ao fogo, no comportamento da ligação laminado-betão

    Laccase partition in ATPS: finding some molecular descriptors

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    Aqueous Two-Phase Systems (ATPS) are known since 1896, when Beijerinck reported the formation of a biphasic system after mixing aqueous solutions of gelatine and agar or gelatine and starch. However, only in the 50’s, Albertsson showed the potential of these systems in the separation and purification of several biological constituents.1 In general, ATPS are obtained by mixing two aqueous solutions of different constituents that become immiscible above certain critical conditions, like temperature, concentration, etc. Both phases are composed mainly by water (>80%) and each one is enriched in a different component. ATPS formed by two polymers or a polymer and a salt represent the traditional systems. Nevertheless, other alternative biphasic systems can be obtained using surfactants, micellar compounds or ionic liquids

    Above ground biomass functions with vegetation indices for multiple use systems of two evergreen oaks

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    Remote sensing is a promising approach for above ground biomass estimation, as forest parameters can be obtained indirectly. The analysis in space and time is quite straight forward due to the flexibility of the method to determine forest crown parameters with remote sensing. It can be used to evaluate and monitoring for example the development of a forest area in time and the impact of disturbances, such as silvicultural practices or deforestation. The vegetation indices, which condense data in a quantitative numeric manner, have been used to estimate several forest parameters, such as the volume, basal area and above ground biomass. The objective of this study was the development of allometric functions to estimate above ground biomass using vegetation indices as independent variables. The vegetation indices used were the Normalized Difference Vegetation Index (NDVI), Enhanced Vegetation Index (EVI), Simple Ratio (SR) and Soil-Adjusted Vegetation Index (SAVI). QuickBird satellite data, with 0.70 m of spatial resolution, was orthorectified, geometrically and atmospheric corrected, and the digital number were converted to top of atmosphere reflectance (ToA). Forest inventory data and published allometric functions at tree level were used to estimate above ground biomass per plot. Linear functions were fitted for the monospecies and multispecies stands of two evergreen oaks (Quercus suber and Quercus rotundifolia) in multiple use systems, montados. The allometric above ground biomass functions were fitted considering the mean and the median of each vegetation index per grid as independent variable. Species composition as a dummy variable was also considered as an independent variable. The linear functions with better performance are those with mean NDVI or mean SR as independent variable. Noteworthy is that the two better functions for monospecies cork oak stands have median NDVI or median SR as independent variable. When species composition dummy variables are included in the function (with stepwise regression) the best model has median NDVI as independent variable. The vegetation indices with the worse model performance were EVI and SAVI

    A simple microfluidic device for the deformability assessment of blood cells in a continuous flow

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    Blood flow presents several interesting phenomena in microcirculation that can be used to develop microfluidic devices capable to promote blood cells separation and analysis in continuous flow. In the last decade there have been numerous microfluidic studies focused on the deformation of red blood cells (RBCs) flowing through geometries mimicking microvessels. In contrast, studies focusing on the deformation of white blood cells (WBCs) are scarce despite this phenomenon often happens in the microcirculation. In this work, we present a novel integrative microfluidic device able to perform continuous separation of a desired amount of blood cells, without clogging or jamming, and at the same time, capable to assess the deformation index (DI) of both WBCs and RBCs. To determine the DI of both WBCs and RBCs, a hyperbolic converging microchannel was used, as well as a suitable image analysis technique to measure the DIs of these blood cells along the regions of interest. The results show that the WBCs have a much lower deformability than RBCs when subjected to the same in vitro flow conditions, which is directly related to their cytoskeleton and nucleus contents. The proposed strategy can be easily transformed into a simple and inexpensive diagnostic microfluidic system to simultaneously separate and assess blood cells deformability.The authors acknowledge the financial support provided by PTDC/SAU-ENB/116929/2010 and EXPL/EMS-SIS/ 2215/2013 from FCT (Fundação para a Ciência e a Tecnologia), COMPETE, QREN and European Union (FEDER). R. O. Rodrigues, D. Pinho and V. Faustino acknowledge respectively, the PhD scholarships SFRH/BD/97658/2013, SFRH/BD/89077/2012 and SFRH/BD/99696/ 2014 granted by FCT. The authors would also like to thank Dr. Ângela Fernandes for providing the blood samples and Dr. Ricardo Calhelha for supplying the tissue culture medium used in this work.info:eu-repo/semantics/publishedVersio

    Controle do alho-macho (Sisyrinchium platense Johnst): pesquisas realizadas na Embrapa Pecuária Sul.

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