Approximate Discrete Probability Distribution Representation using a Multi-ResolutionBinary Tree

Computing and storing probabilities is a hard problem as soon as one has to deal with complex distributions over multiples random variables. The problem of efficient representation of probability distributions is central in term of computational efficiency in the field of probabilistic reasoning. The main problem arises when dealing with joint probability distributions over a set of random variables: they are always represented using huge probability arrays. In this paper, a new method based on a binary-tree representation is introduced in order to store efficiently very large joint distributions. Our approach approximates any multidimensional joint distributions using an adaptive discretization of the space. We make the assumption that the lower is the probability mass of a particular region of feature space, the larger is the discretization step. This assumption leads to a very optimized representation in term of time and memory. The other advantages of our approach are the ability to refine dynamically the distribution every time it is needed leading to a more accurate representation of the probability distribution and to an anytime representation of the distribution

Resolving the internal magnetic structure of the solar network

We analyze the spectral asymmetry of Stokes V (circularly polarized) profiles of an individual network patch in the quiet Sun observed by Sunrise/IMaX. At a spatial resolution of 0.15"-0.18", the network elements contain substructure which is revealed by the spatial distribution of Stokes V asymmetries. The area asymmetry between the red and blue lobes of Stokes V increases from nearly zero at the core of the structure to values close to unity at its edges (one-lobed profiles). Such a distribution of the area asymmetry is consistent with magnetic fields expanding with height, i.e., an expanding magnetic canopy (which is required to fulfill pressure balance and flux conservation in the solar atmosphere). Inversion of the Stokes I and V profiles of the patch confirms this picture, revealing a decreasing field strength and increasing height of the canopy base from the core to the periphery of the network patch. However, the non-roundish shape of the structure and the presence of negative area and amplitude asymmetries reveal that the scenario is more complex than a canonical flux tube expanding with height surrounded by downflows.Comment: accepted for publication in ApJ Letter

Maltose-binding protein is a potential carrier for oral immunizations

In humans and most animal species such as pigs, vaccination via the oral route is a prerequisite for induction of a protective immunity against enteropathogens. Hereto, live attenuated microorganisms can be used. However, these microorganisms often are either too attenuated to induce sufficient intestinal immunity or are still too virulent resulting in clinical signs. We previously demonstrated that it is possible to induce immunity against enteropathogens by targeting antigen towards enterocytes. Maltose-binding protein (MBP) is part of the maltose/maltodextrin system of Escherichia coli. MBP is a relatively small protein (42.5 kDa) approximately 3 × 4 × 6.5 nm in size with surface residues capable of both hydrogen bonding interactions and hydrophobic interactions. Recombinant proteins are often fused to MPB to improve their yield and to increase their solubility. In mice, these fusion proteins showed an enhanced immunogenicity following systemic immunization. More recently, this has been attributed to interaction of MBP with TLR4 on dendritic cells (DCs). TLR4 is also expressed in the enterocytes of the gut. Therefore, we examined if oral administration of MPB-FedF to 4-week-old pigs could be used to induce an immune response against F18+ verotoxigenic E. coli in pigs. Also we examined if the oral administration of MBP to pigs is able to induce an immune response. In both experiments cholera toxin was used as oral adjuvant

Orphan penumbrae: Submerging horizontal fields

We investigate the properties of orphan penumbrae, which are photospheric filamentary structures observed in active regions near polarity inversion lines that resemble the penumbra of regular sunspots but are not connected to any umbra. We use Hinode data from the Solar Optical Telescope to determine the properties of orphan penumbrae. Spectropolarimetric data are employed to obtain the vector magnetic field and line-of-sight velocities in the photosphere. Magnetograms are used to study the overall evolution of these structures, and G-band and Ca II H filtergrams are to investigate their brightness and apparent horizontal motions. Orphan penumbrae form between regions of opposite polarity in places with horizontal magnetic fields. Their magnetic configuration is that of $\Omega$-shaped flux ropes. In the two cases studied here, the opposite-polarity regions approach each other with time and the whole structure submerges as the penumbral filaments disappear. Orphan penumbrae are very similar to regular penumbrae, including the existence of strong gas flows. Therefore, they could have a similar origin. The main difference between them is the absence of a "background" magnetic field in orphan penumbrae. This could explain most of the observed differences. The fast flows we detect in orphan penumbrae may be caused by the siphon flow mechanism. Based on the similarities between orphan and regular penumbrae, we propose that the Evershed flow is also a manifestation of siphon flows.Comment: 15 pages, 15 figure

Abastament d'aigua en comunitats rurals de El Salvador: Propostes per a la sostenibilitat social.

El capítulo de ejecución puede significar el 80% de la asignación presupuestaria en los proyectos de infraestructura en general, y los de abastecimiento y saneamiento de agua en particular. Sin embargo, factores como seguimiento, evaluación, capacitación, legalización, o sensibilización, a menudo de difícil -si no imposible- justificación económica ante financiadores y donantes, pueden llegar a constituir entre el 80% y el 90% de las causas de fracaso de los proyectos. Este artículo expone la metodología que Ingeniería Sin Fronteras Cataluña (ESF) y la Asociación de Desarrollo Comunal –El Salvador (CORDES) han desarrollado desde el año 1999 en áreas rurales de El Salvador en los aspectos no puramente técnicos de los proyectos que garanticen su sostenibilidad social. Pretende que resulte de utilidad para otros profesionales u organizaciones que trabajen también en el campo del agua en comunidades rurales.El capítol d'execució pot significar el 80% de l'assignació pressupostària en els projectes d'infrastructura en general, i en els d'abastament i sanejament d'aigua en particular. No obstant, factors com ara el seguiment, avaluació, capacitació, legalització, o sensibilització, sovint de difícil -si no impossible- justificació econòmica davant de finançadors i donants, poden arribar a constituir entre el 80% i el 90% de les causes de fracàs dels projectes. Aquest article exposa la metodologia que Enginyeria Sense Fronteres Catalunya (ESF) i l'Associació de Desenvolupament Comunal –El Salvador (CORDES) han desenvolupat des de l'any 1999 en àrees rurals del Salvador en els aspectes no purament tècnics dels projectes que garanteixin la seva sostenibilitat social. Pretén resultar d'utilitat per a altres professionals o organitzacions que treballen també al sector de l'aigua en comunitats rurals.Peer Reviewe