Scalar field confinement as a model for accreting systems

We investigate the possibility to localize scalar field configurations as a model for black hole accretion. We analyze and resolve difficulties encountered when localizing scalar fields in General Relativity. We illustrate this ability with a simple spherically symmetric model which can be used to study features of accreting shells around a black hole. This is accomplished by prescribing a scalar field with a coordinate dependent potential. Numerical solutions to the Einstein-Klein-Gordon equations are shown, where a scalar filed is indeed confined within a region surrounding a black hole. The resulting spacetime can be described in terms of simple harmonic time dependence.Comment: 18 pages; accepted for publication in Classical and Quantum Gravit

Tropical cyclone rainbands can trigger meteotsunamis

© The Author(s), 2020. This article is distributed under the terms of the Creative Commons Attribution License. The definitive version was published in Shi, L., Olabarrieta, M., Nolan, D. S., & Warner, J. C. Tropical cyclone rainbands can trigger meteotsunamis. Nature Communications, 11(1), (2020): 678, doi:10.1038/s41467-020-14423-9.Tropical cyclones are one of the most destructive natural hazards and much of the damage and casualties they cause are flood-related. Accurate characterization and prediction of total water levels during extreme storms is necessary to minimize coastal impacts. While meteotsunamis are known to influence water levels and to produce severe consequences, their impacts during tropical cyclones are underappreciated. This study demonstrates that meteotsunami waves commonly occur during tropical cyclones, and that they can contribute significantly to total water levels. We use an idealized coupled ocean–atmosphere–wave numerical model to analyze tropical cyclone-induced meteotsunami generation and propagation mechanisms. We show that the most extreme meteotsunami events are triggered by inherent features of the structure of tropical cyclones: inner and outer spiral rainbands. While outer distant spiral rainbands produce single-peak meteotsunami waves, inner spiral rainbands trigger longer lasting wave trains on the front side of the tropical cyclones.We thank all the developers of COAWST, ROMS, WRF, and SWAN models. D.N. was supported by NSF grant AGS-1654831. We would like to thank Dr. K. Bagamian for her editorial and writing suggestions. We would like to thank Dr. A. Aretxabaleta for the internal US Geological Survey internal revision and suggestions

Critical Behavior in the Gravitational Collapse of a Scalar Field with Angular Momentum in Spherical Symmetry

We study the critical collapse of a massless scalar field with angular momentum in spherical symmetry. In order to mimic the effects of angular momentum we perform a sum of the stress-energy tensors for all the scalar fields with the same eigenvalue, l, of the angular momentum operator and calculate the equations of motion for the radial part of these scalar fields. We have found that the critical solutions for different values of l are discretely self-similar (as in the original l=0 case). The value of the discrete, self-similar period, Delta_l, decreases as l increases in such a way that the critical solution appears to become periodic in the limit. The mass scaling exponent, gamma_l, also decreases with l.Comment: 10 pages, 8 figure

¿Cómo elegir un manual de Francés Lengua Extranjera?

Sin resume

DESCAYRAC, C. (1990): Une année en France. Langue et civilisation.

Sin resume

La enseñanza de la civilización en la clase de lengua extranjera.

Sin resume

GARABEDIAN, M., LERASLE, M., MEYER-DREUX, S. (1992). Trampoline I, II. Méthode de Français.

Sin resume

The role of morphology and wave-current interaction at tidal inlets : an idealized modeling analysis

Author Posting. © American Geophysical Union, 2014. This article is posted here by permission of American Geophysical Union for personal use, not for redistribution. The definitive version was published in Journal of Geophysical Research: Oceans 119 (2014): 8818–8837, doi:10.1002/2014JC010191.The outflowing currents from tidal inlets are influenced both by the morphology of the ebb-tide shoal and interaction with incident surface gravity waves. Likewise, the propagation and breaking of incident waves are affected by the morphology and the strength and structure of the outflowing current. The 3-D Coupled Ocean-Atmosphere-Wave-Sediment Transport (COAWST) modeling system is applied to numerically analyze the interaction between currents, waves, and bathymetry in idealized inlet configurations. The bathymetry is found to be a dominant controlling variable. In the absence of an ebb shoal and with weak wave forcing, a narrow outflow jet extends seaward with little lateral spreading. The presence of an ebb-tide shoal produces significant pressure gradients in the region of the outflow, resulting in enhanced lateral spreading of the jet. Incident waves cause lateral spreading and limit the seaward extent of the jet, due both to conversion of wave momentum flux and enhanced bottom friction. The interaction between the vorticity of the outflow jet and the wave stokes drift is also an important driving force for the lateral spreading of the plume. For weak outflows, the outflow jet is actually enhanced by strong waves when there is a channel across the bar, due to the “return current” effect. For both strong and weak outflows, waves increase the alongshore transport in both directions from the inlet due to the wave-induced setup over the ebb shoal. Wave breaking is more influenced by the topography of the ebb shoal than by wave-current interaction, although strong outflows show intensified breaking at the head of the main channel.We are grateful to the Career Training Interexchange program that facilitated the training period of Maitane Olabarrieta within the USGS. Maitane Olabarrieta also acknowledges funding from the “Cantabria Campus International Augusto Gonzalez Linares Program.”WRG was supported by ONR grant N00014-13-1–0368.2015-06-2

Análisis de las estrategias de diferenciación y posicionamiento de los centros comerciales planificados como formato de distribución

Los centros comerciales planificados son un formato de distribución que ha alcanzado un importante nivel de desarrollo en nuestro país. Por su parte, el incremento del número de centros comerciales operativos está generando un aumento significativo del nivel de competencia entre los mismos. Así, este trabajo pretende un acercamiento general a la realidad actual del formato de los centros comerciales, centrándonos más detalladamente en el ámbito del Territorio Histórico de Vizcaya. El objetivo central de la investigación es el análisis de las estrategias de diferenciación y posicionamiento de los centros comerciales planificados, abordándose asimismo diferentes aspectos relacionados con la gestión de marketing. En el trabajo se lleva a cabo una revisión de la literatura académica más relevante desarrollada en los últimos años en torno a esta temática. Asimismo, se ha desarrollado una investigación empírica de carácter cualitativo, a través de la cual quedan definidos aspectos relevantes de la gestión de marketing de los centros, así como la constatación de la existencia de dos líneas destacadas de diferenciación y posicionamiento: las líneas basadas en los factores “proximidad” y “centro repleto de vida y actividad”.Planned shopping centres as distribution form have achieved a very important level of development in our country. Also, the increasing number of operating shopping centres is creating a growing level of competition. Thus, this paper pretends a general approach to the current situation of the shopping centre form, focusing that approach more precisely in the Historic Territory of Biscay. The main objective of the investigation is the analysis of the differentiation and positioning strategies of planned shopping centres; also, and directly related, the investigation is focused on different aspects of the marketing management area. A review of the more relevant academic literature developed in recent years related to the objectives of the study has been undertaken. In the same way, an empiric qualitative research has been undertaken in order to define relevant aspects of the centres´ marketing management; the results of the qualitative research show two main lines of differentiation and positioning: these lines are the ones based on two factors: “proximity” and “mall full of life and activity

A Comparison of Modelling Approaches for the Long-term Estimation of Origin Destination Matrices in Bike Sharing Systems

Micro-mobility services have gained popularity in the last years, becoming a relevant part of the transportation network in a plethora of cities. This has given rise to a fruitful research area, covering from the impact and relationships of these transportation modes with preexisting ones to the different ways for estimating the demand of such services in order to guarantee the quality of service. Within this domain, docked bike sharing systems constitute an interesting surrogate for understanding the mobility of the whole city, as origin-destination matrices can be obtained straightforward from the information available at the docking stations. This work elaborates on the characterization of such origin-destination matrices, providing an essential set of insights on how to estimate their behavior in the long-term. To do so, the main non-mobility features that affect mobility are studied and used to train different machine learning algorithms to produce viable mobility patterns. The case study performed over real data captured by the bike sharing system of Bilbao (Spain) reveals that, by virtue of a properly selected set of features and the adoption of specialized modeling algorithms, reliable long-term estimations of such origin-destination matrices can be effectively achieved