Beyond the simple Proximity Force Approximation: geometrical effects on the non-retarded Casimir interaction

We study the geometrical corrections to the simple Proximity Force Approximation for the non-retarded Casimir force. We present analytical results for the force between objects of various shapes and substrates, and between pairs of objects. We compare the results to those from more exact numerical calculations. We treat spheres, spheroids, cylinders, cubes, cones, and wings; the analytical PFA results together with the geometrical correction factors are summarized in a table.Comment: 18 pages, 19 figures, 1 tabl

ANCSA and 1991: A Framework for Analysis

We study the geometrical corrections to the simple Proximity Force Approximation (PFA) for the non-retarded Casimir force. We extend traditional PFA in two ways: We take the whole surfaces of the objects facing each other into account, not just the curvatures at the point of closest distance; we take the thickness of the coating of coated objects into account in the formalism. We present analytical and numerical results for a sphere above a substrate, for a spherical shell above a substrate, and for two interacting spheres. We compare the results to those from a multi-polar expansion method, a method based on a more solid foundation.Original Publication: Bo E. Sernelius and C.E. Roman-Velazquez, Test of the proximity force approximation, 2009, Journal of Physics: Conference Series, (161), 012016. http://dx.doi.org/10.1088/1742-6596/161/1/012016 Copyright: Institute of Physics http://journals.iop.org/</p

An MHD study of SN 1006 and determination of the ambient magnetic field direction

In this work we employ an MHD numerical code to reproduce the morphology observed for SN 1006 in radio synchrotron and thermal X-ray emission. We introduce a density discontinuity, in the form of a flat cloud parallel to the Galactic Plane, in order to explain the NW filament observed in optical wavelengths and in thermal X-rays. We compare our models with observations. We also perform a test that contrasts the radio emitting bright limbs of the SNR against the central region, finding additional support to our results. Our main conclusion is that the most probable direction of the ambient magnetic field is on average perpendicular to the Galactic Plane.Comment: 7 pages, 5 figures, accepted by MNRA

International Evidence on Stochastic and Deterministic Monetary Neutrality.

We analyze the issue of the impact of multiple breaks on monetary neutrality results, using a long annual international data set. We empirically verify whether neutrality propositions remain addressable (and if so, whether they hold or not), when unit root tests are carried out allowing for multiple structural breaks in the long-run trend function of the variables. It is found that conclusions on neutrality are sensitive to the number and location of breaks. In order to interpret the evidence for structural breaks, we introduce a notion of deterministic monetary neutrality, which naturally arises in the absence of permanent stochastic shocks to the variables.Deterministic and Stochastic Neutrality and Superneutrality of Money, Unit Roots, Structural Breaks, Resampling Methods

3D MHD simulation of polarized emission in SN 1006

We use three dimensional magnetohydrodynamic (MHD) simulations to model the supernova remnant SN 1006. From our numerical results, we have carried out a polarization study, obtaining synthetic maps of the polarized intensity, the Stokes parameter $Q$, and the polar-referenced angle, which can be compared with observational results. Synthetic maps were computed considering two possible particle acceleration mechanisms: quasi-parallel and quasi-perpendicular. The comparison of synthetic maps of the Stokes parameter $Q$ maps with observations proves to be a valuable tool to discern unambiguously which mechanism is taking place in the remnant of SN 1006, giving strong support to the quasi-parallel model.Comment: 6 pages, 4 figures, accepted by MNRA

La paternidad: un camino en construcción

Actualmente, ante los cambios sociales de hombres y mujeres, el papel de la paternidad ha sufrido diversas modificaciones, ha pasado de un modelo rígido y dominante a una estructura más flexible e igualitaria; de sólo proveedor económico a proveedor de cuidados, afectos, enseñanza, formación y, también, económico. Dado que el ser padre constituye una de las experiencias más valoradas por los varones, en este estudio se analizan las vivencias de diversos aspectos de la paternidad en varones españoles. Aquí se examina: su formación para la paternidad, sus responsabilidades, temores, limitaciones, su concepto de autoridad paterna, sus satisfacciones y las diferencias y semejanzas con la paternidad de sus padres. Se encuentra que los varones están en transición de un modelo tradicional a un nuevo modelo inacabado, que los varones no tienen un modelo al cual adherirse y que han cambiado con respecto a la paternidad de sus padres.Currently, due to the social changes of men and women, the role of the father has suffered diverse modifications; it has gone from a rigid and dominant model to a more flexible and equivalent structure. The father has gone from merely an economic provider to a provider of care, affection, teachings, formation, and economic provision. Given that to be a father is one of the experiences that is most valued by men in this study analyzes the different paternal aspects in Spanish males along with their formation as fathers, their responsibilities, their fears, their limitations; their concept of fatherly authority, their satisfactions, and the differences and similarities with the paternity of their fathers. This study come upon males are in transition from a traditional model to a new unfinished model, they do not have a model to adhere to, and they have changed with respect to the paternity of their fathers

Numerical study of the effect of structure and geometry on van der Waals forces

We use multipolar expansions to find the force on a gold coated sphere above a gold substrate; we study both an empty gold shell and a gold coated polystyrene sphere. We find four characteristic separation ranges. In the first region, which for the empty gold shell occurs for distances, d, smaller than the thickness of the coating, the result agrees with that on a solid gold sphere and varies as d^(-2); for larger separations there is a region where the force behaves as if the coating is strictly two dimensional and varies as d^(-5/2); in the third region the dependence is more unspecific; in the forth region when d is larger than the radius, the force varies as d^(-4). For homogeneous objects of more general shapes we introduce a numerical method based on the solution of an integral equation for the electric field over a system of objects with arbitrary shapes. We study the effect of shape and orientation on the van der Waals interaction between an object and a substrate and between two objects.Comment: 8 pages, presented in the QFEXT07 conference, submitted to Journal of Physics