Non-circular rotating beams and CMB experiments

This paper is concerned with small angular scale experiments for the observation of cosmic microwave background anisotropies. In the absence of beam, the effects of partial coverage and pixelisation are disentangled and analyzed (using simulations). Then, appropriate maps involving the CMB signal plus the synchrotron and dust emissions from the Milky Way are simulated, and an asymmetric beam --which turns following different strategies-- is used to smooth the simulated maps. An associated circular beam is defined to estimate the deviations in the angular power spectrum produced by beam asymmetry without rotation and, afterwards, the deviations due to beam rotation are calculated. For a certain large coverage, the deviations due to pure asymmetry and asymmetry plus rotation appear to be very systematic (very similar in each simulation). Possible applications of the main results of this paper to data analysis in large coverage experiments --as PLANCK-- are outlined.Comment: 13 pages, 9 figures, to appear in A&

On the use of the Bingham statistical distribution in microsphere-based constitutive models for arterial tissue

Constitutive models for arterial tissue have been an active research field during the last years. The main micro-constituents of blood vessels are different types of cells and the extra-cellular matrix formed by an isotropic high water content ground substance and a network composed of elastin and collagen fibres. Usually the arterial tissue has been modelled as a hyperelastic material within the framework of continuum mechanics, whereas inclusion of structural tensors into constitutive laws is the most widely used technique to introduce the anisotropy induced by the fibres. Though the different existing fibre bundles present a clear preferential direction, the dispersion inherent to biological tissue advices using of constitutive models including representative structural information associated to the spatial probabilistic distribution of the fibres. Lately, microsphere-based models have demonstrated to be a powerful tool to incorporate this information. The fibre dispersion is incorporated by means of an Orientation Density Function (ODF) that weights the contribution of each fibre in each direction of the micro-sphere. In previous works the rotationally symmetric von Mises ODF was successfully applied to the modelling of blood vessels. In this study, the inclusion of the Bingham ODF into microsphere-based model is analysed. This ODF exhibits some advantages with respect to the von Mises one, like a greater versatility and a comparable response to simple tension and equibiaxial tension tests.Peer ReviewedPostprint (author's final draft

Anisotropic microsphere-based approach to damage in soft fibered tissue

The final publication is available at Springer via http://dx.doi.org/10.1007/s10237-011-0336-9An anisotropic damage model for soft fibered tissue is presented in this paper, using a multi-scale scheme and focusing on the directionally dependent behavior of these materials. For this purpose, a micro-structural or, more precisely, a microsphere-based approach is used to model the contribution of the fibers. The link between micro-structural contribution and macroscopic response is achieved by means of computational homogenization, involving numerical integration over the surface of the unit sphere. In order to deal with the distribution of the fibrils within the fiber, a von Mises probability function is incorporated, and the mechanical (phenomenological) behavior of the fibrils is defined by an exponential-type model. We will restrict ourselves to affine deformations of the network, neglecting any cross-link between fibrils and sliding between fibers and the surrounding ground matrix. Damage in the fiber bundles is introduced through a thermodynamic formulation, which is directly included in the hyperelastic model. When the fibers are stretched far from their natural state, they become damaged. The damage increases gradually due to the progressive failure of the fibrils that make up such a structure. This model has been implemented in a finite element code, and different boundary value problems are solved and discussed herein in order to test the model features. Finally, a clinical application with the material behavior obtained from actual experimental data is also presented.Peer ReviewedPostprint (author's final draft

Sonoelectrochemical Synthesis of Nanoparticles

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Estimating small angular scale CMB anisotropy with high resolution N-body simulations: weak lensing

We estimate the impact of weak lensing by strongly nonlinear cosmological structures on the cosmic microwave background. Accurate calculation of large $\ell$ multipoles requires N-body simulations and ray-tracing schemes with both high spatial and temporal resolution. To this end we have developed a new code that combines a gravitational Adaptive Particle-Particle, Particle-Mesh (AP3M) solver with a weak lensing evaluation routine. The lensing deviations are evaluated while structure evolves during the simulation so that all evolution steps--rather than just a few outputs--are used in the lensing computations. The new code also includes a ray-tracing procedure that avoids periodicity effects in a universe that is modeled as a 3-D torus in the standard way. Results from our new simulations are compared with previous ones based on Particle-Mesh simulations. We also systematically investigate the impact of box volume, resolution, and ray-tracing directions on the variance of the computed power spectra. We find that a box size of $512 h^{-1}$ Mpc is sufficient to provide a robust estimate of the weak lensing angular power spectrum in the $\ell$-interval (2,000--7,000). For a reaslistic cosmological model the power $[\ell(\ell+1)C_{\ell}/2\pi]^{1/2}$ takes on values of a few $\mu K$ in this interval, which suggests that a future detection is feasible and may explain the excess power at high $\ell$ in the BIMA and CBI observations.Comment: 49 pages, 13 figures, accepted for publication in Ap

Reducing depopulation in rural Spain: The impact of immigration

The attraction of foreign-born immigrants to rural areas in developed countries has aroused growing interest in recent years. The central issue in this study is the demographic impact of immigration in rural Spain, focusing on depopulated areas. The economic and demographic consequences of depopulation have become major concerns, and the arrival of international migrants has come to be seen as a possible solution. The aim of this study is to add to a literature in which qualitative research and local or regional perspectives predominate. The present research draws on quantitative findings for a significant part of Spain. The evidence in this study is principally based on population figures for the last years of the 20th century, a period of low immigration to Spain, and the early years of the 21st century, when the inflow of foreign migrants gathered intensity. We also explore the early consequences of the present economic crisis, which began in 2008. The analysis is based on estimates of native and foreign-born population growth for a range of territorial aggregations. Counterfactual techniques are also used. The results show that the arrival of immigrants has so far contributed substantially to reducing and even halting or reversing depopulation. A further series of analyses concentrates on the potential of rural areas to retain immigrants in the long run. The study also recommends a comprehensive policy approach in this regard

CMB anisotropy: deviations from Gaussianity due to non-linear gravity

Non-linear evolution of cosmological energy density fluctuations triggers deviations from Gaussianity in the temperature distribution of the cosmic microwave background. A method to estimate these deviations is proposed. N-body simulations -- in a $\Lambda$CDM cosmology -- are used to simulate the strongly non-linear evolution of cosmological structures. It is proved that these simulations can be combined with the potential approximation to calculate the statistical moments of the CMB anisotropies produced by non-linear gravity. Some of these moments are computed and the resulting values are different from those corresponding to Gaussianity.Comment: 6 latex pages with mn.sty, 3 eps figures. Accepted in MNRA

Percepción del uso de leche de cabra como parte del tratamiento a la alergia a la proteína de leche de vaca (APLV) en la región Metropolitana, Chile

La alergia a la proteína de leche de vaca (APLV) es una condición que afecta a un grupo de entre 2-3% de niños menores de tres años y que genera un gran impacto en la salud de los niños que la padecen, así como en los aspectos sociales y económicos de las familias afectadas, debido al alto costo de las formulas alimenticias que se emplean en el tratamiento de esta alergia alimentaria, por lo cual surge la necesidad de nuevas alternativas amplíen oferta existente. Debido a lo anterior, se realizó un estudio sobre la actitud, creencias y conocimientos de padres de familias con niños que sufren de APLV y de un grupo de informantes calificados, el nivel de satisfacción respecto de la actual oferta de productos alimenticios, y en particular, sobre su percepción frente al posible uso de leche cabra como parte del tratamiento de dicha patología. El estudio fue realizado mediante un enfoque exploratorio por medio de técnicas de investigación cualitativa, incluyendo sesiones de grupos focales y entrevistas a informantes calificados. A partir de los antecedentes recopilados, se puede concluir que existe una demanda insatisfecha por parte de las familias con niños que sufren de APLV, lo que se explicaría por la poca variedad y alto costo de los productos alimenticios en los esquemas terapéuticos, por lo que el uso de productos lácteos como apoyo a los esquemas de alimentación tendría una buena aceptabilidad por parte de padres, en la medida que dichos productos cuenten con información adecuada y contribuyan a disminuir los costos del tratamiento