Diffeomorphisms from higher dimensional W-algebras

Classical W-algebras in higher dimensions have been recently constructed. In this letter we show that there is a finitely generated subalgebra which is isomorphic to the algebra of local diffeomorphisms in D dimensions. Moreover, there is a tower of infinitely many fields transforming under this subalgebra as symmetric tensorial one-densities. We also unravel a structure isomorphic to the Schouten symmetric bracket, providing a natural generalization of w_\infty in higher dimensions.Comment: 10 page

On the stability of circular orbits in galactic dynamics: Newtonian thin disks

The study of off-equatorial orbits in razor-thin disks is still in its beginnings. Contrary to what was presented in the literature in recent publications, the vertical stability criterion for equatorial circular orbits cannot be based on the vertical epicyclic frequency, because of the discontinuity in the gravitational field on the equatorial plane. We present a rigorous criterion for the vertical stability of circular orbits in systems composed by a razor-thin disk surrounded by a smooth axially symmetric distribution of matter, the latter representing additional structures such as thick disk, bulge and (dark matter) halo. This criterion is satisfied once the mass surface density of the thin disk is positive. Qualitative and quantitative analyses of nearly equatorial orbits are presented. In particular, the analysis of nearly equatorial orbits allows us to construct an approximate analytical third integral of motion in this region of phase-space, which describes the shape of these orbits in the meridional plane.Comment: 3 pages, 1 figure. In Proceedings of the MG13 Meeting on General Relativity, Stockholm University, Sweden, 1-7 July 2012. World Scientific, Singapore. Based on arXiv:1206.6501. in The Thirteenth Marcel Grossmann Meeting: On Recent Developments in Theoretical and Experimental General Relativity, Astrophysics, and Relativistic Field Theories (In 3 Volumes), chap. 438, pages 2346-2348 (2015

System dynamics modelling in systems biology and applications in pharmacology

El modelado matemático de sistemas biológicos complejos es uno de los temas clave en la Biología de Sistemas y varios métodos computacionales basados ​​en la simulación computarizada han sido aplicados hasta ahora para determinar el comportamiento de los sistemas no lineales. La Dinamica de Sistemas es una metodología de modelado intuitivo basada en el razonamiento cualitativo por el cual un modelo conceptual se puede describir como un conjunto de relaciones de causa y efecto entre las variables de un sistema. A partir de esta estructura, es posible obtener un conjunto de ecuaciones dinámicas que describan cuantitativamente el comportamiento del sistema. Centrándose en los sistemas farmacológicos, el modelado compartimental a menudo se utiliza para resolver un amplio espectro de problemas relacionados con la distribución de materiales en los sistemas vivos en la investigación, el diagnóstico y la terapia en todo el cuerpo, los órganos y los niveles celulares. En este artículo presentamos la metodología de modelado de Dinámica del Sistema y su aplicación al modelado de un modelo compartimental farmacocinético-farmacodinámico del efecto de profundidad anestésica en pacientes sometidos a intervenciones quirúrgicas, derivando un modelo de simulación en el entorno de simulación orientada a objetos OpenModelica. La Dinamica de Sistemas se puede ver como una herramienta educativa poderosa y fácil de usar y en la enseñanza de Biología de Sistemas.Universidad de Málaga. Campus de Excelencia Internacional Andalucía Tech

Polarimetry SAR detectors for monitoring Mediterranean forest fires events

Over the past decades, the great technological advances made in airborne and space sensors have led to a significant improvement of the remote sensing methods and techniques used for studying worldwide natural ecosystem disturbances. Generally, optical sensors are chosen for investigating landscapes transformation, however, this technology requires certain technical and environmental conditions (sunlight, no cloud-coverage) which are problematic for monitoring some regions of the world. In response to this challenge, this research aims to highlight the capabilities of Synthetic Aperture Radar - SAR satellite sensors for detecting disturbances in Mediterranean forests due to fire events. We are exploring three different methodologies: 1. Monitoring image intensity changes in dense time series of radar data; 2. We are investigating soil moisture changes after the fire that can be detected in intensities of radar images; 3. We are testing novel polarimetric SAR change detectors that are able to extract more information from polarimetric data (intensities and cross-correlations between polarimetric channels). All the procedures in this project were developed by using Co & Cross polarised radar satellite data acquired by the ESA-Sentinel-1 system in C-band, using the Doñana national park (Spain) forest fire event in June-July 2017 as a case study