A statistical approach to the inverse problem in magnetoencephalography

Magnetoencephalography (MEG) is an imaging technique used to measure the magnetic field outside the human head produced by the electrical activity inside the brain. The MEG inverse problem, identifying the location of the electrical sources from the magnetic signal measurements, is ill-posed, that is, there are an infinite number of mathematically correct solutions. Common source localization methods assume the source does not vary with time and do not provide estimates of the variability of the fitted model. Here, we reformulate the MEG inverse problem by considering time-varying locations for the sources and their electrical moments and we model their time evolution using a state space model. Based on our predictive model, we investigate the inverse problem by finding the posterior source distribution given the multiple channels of observations at each time rather than fitting fixed source parameters. Our new model is more realistic than common models and allows us to estimate the variation of the strength, orientation and position. We propose two new Monte Carlo methods based on sequential importance sampling. Unlike the usual MCMC sampling scheme, our new methods work in this situation without needing to tune a high-dimensional transition kernel which has a very high cost. The dimensionality of the unknown parameters is extremely large and the size of the data is even larger. We use Parallel Virtual Machine (PVM) to speed up the computation.Comment: Published in at http://dx.doi.org/10.1214/14-AOAS716 the Annals of Applied Statistics (http://www.imstat.org/aoas/) by the Institute of Mathematical Statistics (http://www.imstat.org

Cosmic bulk viscosity through backreaction

We consider an effective viscous pressure as the result of a backreaction of inhomogeneities within Buchert's formalism. The use of an effective metric with a time-dependent curvature radius allows us to calculate the luminosity distance of the backreaction model. This quantity is different from its counterpart for a "conventional" spatially flat bulk viscous fluid universe. Both expressions are tested against the SNIa data of the Union2.1 sample with only marginally different results for the distance-redshift relation and in accordance with the $\Lambda$CDM model. Future observations are expected to be able to discriminate among these models on the basis of indirect measurements of the curvature evolution.Comment: 18 pages, 6 figures, comments and references added, accepted for publication in GR

Desarrollo y fortalecimiento del área de religión y dignidad humana en los centros escolares salesianos (CES)

Gracias por su presencia. Antes de compartir con ustedes el trabajo que se viene desarrollando en los Centros Escolares Salesianos en el ámbito de la evangelización deseo plantearles, con su permiso, dos interrogantes: 1. ¿Un centro escolar católico es tal porque en su propuesta curricular se imparte Religión y consta en la malla curricular? 2. ¿Un centro escolar católico es tal porque se realizan regularmente celebraciones litúrgicas, se prepara para recibir sacramentos, etc.? Con certeza la respuesta a ambas inquietudes ha sido un ¡No! Estamos entonces de acuerdo que las actividades que en ambos casos se mencionan complementan nuestra tarea pero es necesario anclarlas al Proyecto Educativo, de lo contrario se corre el riesgo de convertirse en iniciativas y no en una característica de nuestra oferta educativa

Non-Abelian statistics in the interference noise of the Moore-Read quantum Hall state

We propose noise oscillation measurements in a double point contact, accessible with current technology, to seek for a signature of the non-abelian nature of the \nu=5/2 quantum Hall state. Calculating the voltage and temperature dependence of the current and noise oscillations, we predict the non-abelian nature to materialize through a multiplicity of the possible outcomes: two qualitatively different frequency dependences of the nonzero interference noise. Comparison between our predictions for the Moore-Read state with experiments on \nu=5/2 will serve as a much needed test for the nature of the \nu=5/2 quantum Hall state.Comment: 4 pages, 4 figures v2: typo's corrected, discussions clarified, references adde

Pengaruh Moderasi Word of Mouth Terhadap Hubungan Kepercayaan Dan Keputusan Pembelian Rumah “Paramount Land”

This study aims to determine the effect of moderating variables Word-Of-Mouth on the relationship of Trust and Paramount Land Purchase Decision of house. The study was conducted in several clusters of housing in GadingSerpong. The sampling method used was simple random sampling. The number of samples studied were as many as 200 customers. The collected data is processed and analyzed by the IBMS SPSS 21.The results showed thatthere is significant influence Word of Mouth as a moderating variable on the relationship of Trust and Paramount Land house Purchase Decision. In addition, the Trust as independent variables significantly influence the purchase decision. Word of Mouth as quasi moderator variables (located as independent variablesand moderating variables) significantly influence the purchase decision and have a significant effect as a moderating variable on the relationship between the Trust with the purchase decision