Algebraic treatment of the confluent Natanzon potentials

Using the so(2,1) Lie algebra and the Baker, Campbell and Hausdorff formulas, the Green's function for the class of the confluent Natanzon potentials is constructed straightforwardly. The bound-state energy spectrum is then determined. Eventually, the three-dimensional harmonic potential, the three-dimensional Coulomb potential and the Morse potential may all be considered as particular cases.Comment: 9 page

Stratospheric Variability and Trends in Models Used for the IPCC AR4

Atmosphere and ocean general circulation model (AOGCM) experiments for the Intergovernmental Panel on Climate Change Fourth Assessment Report (AR4) are analyzed to better understand model variability and assess the importance of various forcing mechanisms on stratospheric trends during the 20th century. While models represent the climatology of the stratosphere reasonably well in comparison with NCEP reanalysis, there are biases and large variability among models. In general, AOGCMs are cooler than NCEP throughout the stratosphere, with the largest differences in the tropics. Around half the AOGCMs have a top level beneath ~2 hPa and show a significant cold bias in their upper levels (~10 hPa) compared to NCEP, suggesting that these models may have compromised simulations near 10 hPa due to a low model top or insufficient stratospheric levels. In the lower stratosphere (50 hPa), the temperature variability associated with large volcanic eruptions is absent in about half of the models, and in the models that do include volcanic aerosols, half of those significantly overestimate the observed warming. There is general agreement on the vertical structure of temperature trends over the last few decades, differences between models are explained by the inclusion of different forcing mechanisms, such as stratospheric ozone depletion and volcanic aerosols. However, even when human and natural forcing agents are included in the simulations, significant differences remain between observations and model trends, particularly in the upper tropical troposphere (200 hPa–100 hPa), where, since 1979, models show a warming trend and the observations a cooling trend

Relation-based Galois connections: towards the residual of a relation

Inma P. Cabrera, Pablo Cordero, Manuel Ojeda-Aciego, Relation-based Galois connections: towards the residual of a relation, CMMSE 2017: Proceedings of the 17th International Conference on Mathematical Methods in Science and Engineering ( ISBN: 978-84-617-8694-7) , pp. 469--475We explore a suitable generalization of the notion of Galois connection in which their components are binary relations. Many different approaches are possible depending both on the (pre-)order relation between subsets in the underlying powerdomain and the chosen type of relational composition.Universidad de Málaga. Campus de Excelencia Internacional Andalucía Tech

The Effect of Zonally Asymmetric Ozone Heating on the Northern Hemisphere Winter Polar Stratosphere

[1] Previous modeling studies have found significant differences in winter extratropical stratospheric temperatures depending on the presence or absence of zonally asymmetric ozone heating (ZAOH), yet the physical mechanism causing these differences has not been fully explained. The present study describes the effect of ZAOH on the dynamics of the Northern Hemisphere extratropical stratosphere using an ensemble of free-running atmospheric general circulation model simulations over the 1 December - 31 March period. We find that the simulations including ZAOH produce a significantly warmer and weaker stratospheric polar vortex in mid-February due to more frequent major stratospheric sudden warmings compared to the simulations using only zonal mean ozone heating. This is due to regions of enhanced Eliassen-Palm flux convergence found in the region between 40°N–70°N latitude and 10–0.05 hPa. These results are consistent with changes in the propagation of planetary waves in the presence of ZAOH predicted by an ozone-modified refractive index

Increasing the order of convergence of iterative schemes for solving nonlinear systems

[EN] A set of multistep iterative methods with increasing order of convergence is presented, for solving systems of nonlinear equations. One of the main advantages of these schemes is to achieve high order of convergence with few Jacobian and functional evaluations, joint with the use of the same matrix of coefficients in the most of the linear systems involved in the process. Indeed, the application of the pseudocomposition technique on these proposed schemes allows us to increase their order of convergence, obtaining new high-order, efficient methods. Finally, some numerical tests are performed in order to check their practical behavior. (C) 2012 Elsevier B.V. All rights reserved.This research was supported by Ministerio de Ciencia y Tecnología MTM2011-28636-C02-02 and FONDOCYT 2011-1-B1-33 República DominicanaCordero Barbero, A.; Torregrosa Sánchez, JR.; Penkova Vassileva, M. (2013). Increasing the order of convergence of iterative schemes for solving nonlinear systems. Journal of Computational and Applied Mathematics. 252:86-94. https://doi.org/10.1016/j.cam.2012.11.024S869425

On the notion of fuzzy adjunctions between fuzzy orders

Las adjunciones (también denominadas conexiones de Galois isótonas) entre dos estructuras matemáticas proporcionan una manera de conectar ambas teorías que permite compartir las ventajas de ambas. Hay varios resultados en la literatura previa acerca de las condiciones necesarias y suficientes para la existencia de conexiones de Galois entre dos conjuntos parcialmente ordenados. En otros trabajos anteriores, los autores han estudiado la existencia y construcción del adjunto por la derecha de una aplicación dada entre conjuntos preordenados o dotados de un orden difuso, entendido éste como una relación binaria difusa satisfaciendo reflexividad, transitividad y antisimetría. Se entiende el término adjunción difusa como una pareja de aplicaciones entre dos conjuntos crisp que están dotados de órdenes difusos para las culaes se verifica la condición ρ(a,g(b)) = ρ(f(a),b). Esta definición no está suficientemente justificada en un contexto difuso puesto que las aplicaciones que se consideran se dan entre conjuntos clásicos. En este trabajo se explica la forma en la que la citada definición está relacionada con las funciones difusas, mostrando así que la definición sí es adecuada en ambiente difuso también. La extensión natural de la noción difusa de adjunción contempla dos posibilidades, según si uno considera igualdades difusas o equivalencias difusas asociadas al orden difuso o no.Universidad de Málaga. Campus de Excelencia Internacional Andalucía Tech

Supertubes versus superconducting tubes

In this paper we show the relationship between cylindrical D2-branes and cylindrical superconducting membranes described by a generic effective action at the bosonic level. In the first case the extended objects considered, arose as blown up type IIA superstrings to D2-branes, named supertubes. In the second one, the cosmological objects arose from some sort of field theories. The Dirac-Born-Infeld action describing supertubes is shown to be equivalent to the generic effective action describing superconducting membranes via a special transformation.Comment: Version with minor text changes with respect to the already publishe