Nonparametric Bayesian Mixed-effect Model: a Sparse Gaussian Process Approach

Multi-task learning models using Gaussian processes (GP) have been developed and successfully applied in various applications. The main difficulty with this approach is the computational cost of inference using the union of examples from all tasks. Therefore sparse solutions, that avoid using the entire data directly and instead use a set of informative "representatives" are desirable. The paper investigates this problem for the grouped mixed-effect GP model where each individual response is given by a fixed-effect, taken from one of a set of unknown groups, plus a random individual effect function that captures variations among individuals. Such models have been widely used in previous work but no sparse solutions have been developed. The paper presents the first sparse solution for such problems, showing how the sparse approximation can be obtained by maximizing a variational lower bound on the marginal likelihood, generalizing ideas from single-task Gaussian processes to handle the mixed-effect model as well as grouping. Experiments using artificial and real data validate the approach showing that it can recover the performance of inference with the full sample, that it outperforms baseline methods, and that it outperforms state of the art sparse solutions for other multi-task GP formulations.Comment: Preliminary version appeared in ECML201

The Stationary Phase Method for a Wave Packet in a Semiconductor Layered System. The applicability of the method

Using the formal analysis made by Bohm in his book, {\em "Quantum theory"}, Dover Publications Inc. New York (1979), to calculate approximately the phase time for a transmitted and the reflected wave packets through a potential barrier, we calculate the phase time for a semiconductor system formed by different mesoscopic layers. The transmitted and the reflected wave packets are analyzed and the applicability of this procedure, based on the stationary phase of a wave packet, is considered in different conditions. For the applicability of the stationary phase method an expression is obtained in the case of the transmitted wave depending only on the derivatives of the phase, up to third order. This condition indicates whether the parameters of the system allow to define the wave packet by its leading term. The case of a multiple barrier systems is shown as an illustration of the results. This formalism includes the use of the Transfer Matrix to describe the central stratum, whether it is formed by one layer (the single barrier case), or two barriers and an inner well (the DBRT system), but one can assume that this stratum can be comprise of any number or any kind of semiconductor layers.Comment: 15 pages, 4 figures although figure 4 has 5 graph

Caveolin-1 Modulates Mechanotransduction Responses to Substrate Stiffness through Actin-Dependent Control of YAP

The transcriptional regulator YAP orchestrates many cellular functions, including tissue homeostasis, organ growth control, and tumorigenesis. Mechanical stimuli are a key input to YAP activity, but the mechanisms controlling this regulation remain largely uncharacterized. We show that CAV1 positively modulates the YAP mechanoresponse to substrate stiffness through actin-cytoskeleton-dependent and Hippo-kinase-independent mechanisms. RHO activity is necessary, but not sufficient, for CAV1-dependent mechanoregulation of YAP activity. Systematic quantitative interactomic studies and image-based small interfering RNA (siRNA) screens provide evidence that this actin-dependent regulation is determined by YAP interaction with the 14-3-3 protein YWHAH. Constitutive YAP activation rescued phenotypes associated with CAV1 loss, including defective extracellular matrix (ECM) remodeling. CAV1-mediated control of YAP activity was validated in vivo in a model of pancreatitis-driven acinar-to-ductal metaplasia. We propose that this CAV1-YAP mechanotransduction system controls a significant share of cell programs linked to these two pivotal regulators, with potentially broad physiological and pathological implications. Moreno-Vicente et al. report that CAV1, a key component of PM mechanosensing caveolae, mediates adaptation to ECM rigidity by modulating YAP activity through the control of actin dynamics and phosphorylation-dependent interaction of YAP with the 14-3-3-domain protein YWHAH. Cav1-dependent YAP regulation drives two pathophysiological processes: ECM remodeling and pancreatic ADM. © 2018 The Author

Topological defects and misfit strain in magnetic stripe domains of lateral multilayers with perpendicular magnetic anisotropy

Stripe domains are studied in perpendicular magnetic anisotropy films nanostructured with a periodic thickness modulation that induces the lateral modulation of both stripe periods and inplane magnetization. The resulting system is the 2D equivalent of a strained superlattice with properties controlled by interfacial misfit strain within the magnetic stripe structure and shape anisotropy. This allows us to observe, experimentally for the first time, the continuous structural transformation of a grain boundary in this 2D magnetic crystal in the whole angular range. The magnetization reversal process can be tailored through the effect of misfit strain due to the coupling between disclinations in the magnetic stripe pattern and domain walls in the in-plane magnetization configuration

Revisión de los eventos de afloramiento en Galicia: eventos fuera de temporada en las rías (1967–2009)

Over the last decades several studies have been conducted on upwelling along the Galician coast that have significantly improved the knowledge of this process. These investigations showed that upwelling along this coast is a frequent phenomenon during the spring and summer months, pumping colder Eastern North Atlantic Central Water into the rias. Nevertheless, several upwelling events in autumn and winter have been characterized in the Galician rias, indicating that the upwelling process along the Galician coast is not a phenomenon restricted to spring and summer. In this study the recurrence of these upwelling events has been reviewed from published articles and analyzed from 1967 to 2009 along the western and northern Galician coasts in terms of an upwelling index. The highest mean number of days under favorable upwelling conditions per month was observed during spring and summer on the western (18–26 days) and northern (12–14 days) coasts. During autumn and winter the number of days was lower (11–18 days, western coast; 8–10 days, northern coast) although not negligible, showing the possibility of observing upwelling events during this period. In fact, during these months a significant probability of observing favorable upwelling conditions along both coasts (26%) was found, though the most probable situation corresponded to unfavorable upwelling conditions (44%). The results thus revealed that these events cannot be considered isolated episodes. Upwelling processes in the rias should be observed under favorable conditions, such as prevalence of northerly wind at the adjacent western Galician shelf, independently of the season.Durante las últimas décadas se han llevado a cabo varios estudios relacionados con el fenómeno de afloramiento a lo largo de la costa de Galicia que han mejorado significativamente el conocimiento de este proceso. De los resultados de estos trabajos se ha encontrado que el afloramiento a lo largo de esta costa es un fenómeno frecuente durante los meses de primavera y verano, introduciendo Agua Central del Atlántico Norte en el interior de las rías. Sin embargo, en las rías gallegas se han caracterizado varios eventos de afloramiento durante otoño e invierno que indican que este proceso no es un fenómeno exclusivo de las estaciones de primavera y verano. En este estudio se hace una revisión de estos eventos teniendo en cuenta artículos ya publicados y también se analiza su recurrencia a lo largo de las costas oeste y norte de Galicia a partir de datos de índice de afloramiento de 1967 a 2009. El número medio de días por mes con condiciones favorables de afloramiento más elevado se observó durante los meses de primavera y verano en la costa oeste (18–26 días) y costa norte (12–14 días). Durante otoño e invierno este número de días fue menor (11–18 días, costa oeste; 8–10 días, costa norte) aunque no despreciable, indicando la posibilidad de observar eventos de afloramiento durante este periodo. De hecho, durante estos meses se observó una cierta probabilidad de obtener condiciones favorables de afloramiento a lo largo de ambas costas (26%), aunque la situación más probable correspondió a condiciones desfavorables (44%). Estos resultados revelaron que estos eventos no se pueden considerar como episodios aislados. De esto se deduce que los procesos de afloramiento en las rías deberían ser observados bajo condiciones favorables, tales como vientos predominantes del norte en la plataforma adyacente, independientemente de la estación.publishe

Datos estructurales sobre el anticlinal de "San Emiliano-Valgrande" y unidades periféricas (Cordillera Cantábrica)

Se mencionan algunos datos estructurales sobre el anticlinal mecanizado que se extiende, desde las proximidades de San Emiliano (León) hasta el nacimiento del río Valgrande (Asturias), el cual, resulta ser una muy destacada estructura de replegamiento de la Unidad Cabalgante de Pajares. Se citan algunas otras observaciones sobre el carácter, en estazona, de la Unidad Cabalgante de Villamanín, que se le superpone, adquiriendo aquí una notable complejidad en la zona frontal, definiendo una serie de escamas y, conjuntamente, una semiventana tectónica de cierta importancia