Exponential localization of singular vectors in spatiotemporal chaos

In a dynamical system the singular vector (SV) indicates which perturbation will exhibit maximal growth after a time interval $\tau$. We show that in systems with spatiotemporal chaos the SV exponentially localizes in space. Under a suitable transformation, the SV can be described in terms of the Kardar-Parisi-Zhang equation with periodic noise. A scaling argument allows us to deduce a universal power law $\tau^{-\gamma}$ for the localization of the SV. Moreover the same exponent $\gamma$ characterizes the finite-$\tau$ deviation of the Lyapunov exponent in excellent agreement with simulations. Our results may help improving existing forecasting techniques.Comment: 5 page

Logarithmic bred vectors in spatiotemporal chaos: structure and growth

Bred vectors are a type of finite perturbation used in prediction studies of atmospheric models that exhibit spatially extended chaos. We study the structure, spatial correlations, and the growth- rates of logarithmic bred vectors (which are constructed by using a given norm). We find that, after a suitable transformation, logarithmic bred vectors are roughly piecewise copies of the leading Lyapunov vector. This fact allows us to deduce a scaling law for the bred vector growth rate as a function of their amplitude. In addition, we relate growth rates with the spectrum of Lyapunov exponents corresponding to the most expanding directions. We illustrate our results with simulations of the Lorenz '96 model.Comment: 8 pages, 8 figure

Covariant hydrodynamic Lyapunov modes and strong stochasticity threshold in Hamiltonian lattices

We scrutinize the reliability of covariant and Gram-Schmidt Lyapunov vectors for capturing hydrodynamic Lyapunov modes (HLMs) in one-dimensional Hamiltonian lattices. We show that,in contrast with previous claims, HLMs do exist for any energy density, so that strong chaos is not essential for the appearance of genuine (covariant) HLMs. In contrast, Gram-Schmidt Lyapunov vectors lead to misleading results concerning the existence of HLMs in the case of weak chaos.Comment: 4 pages, 4 figures. Accepted for publication in Physical Review

Chromosome 10 in the tomato plant carries clusters of genes responsible for field resistance/defence to Phytophthora infestans

AbstractThe main objective of the present study was to reanalyse tomato expression data that was previously submitted to the Tomato Expression Database to dissect the resistance/defence genomic and metabolic responses of tomato to Phytophthora infestans under field conditions. Overrepresented gene sets belonging to chromosome 10 were identified using the Gene Set Enrichment Analysis, and we found that these genes tend to be located towards the end of the chromosome 10. An analysis of syntenic regions between Arabidopsis thaliana chromosomes and the tomato chromosome 10 allowed us to identify conserved regions in the two genomes. In addition to allowing for the identification of tomato candidate genes participating in resistance/defence in the field, this approach allowed us to investigate the relationships of the candidate genes with chromosomal position and participation in metabolic functions, thus offering more insight into the phenomena occurring during the infection process

Un sistema de vigilancia en salud pública para alertas tempranas

The paper describes a generic software architecture for Public Health Surveillance information Systems and the implementation of a reporting system for infectious diseases in rural areas, implementing such architecture. The architecture is a component-based, interoperable, flexible and open approach and the system is implemented using open source technologies. The software application has been piloted in the Department of Cauca in Colombia, in the framework of a telemedicine Project funded by the European Union Commission.En este artículo se describe en detalle una arquitectura genérica para Sistemas de Vigilancia en Salud Pública y la implementación de un sistema de vigilancia de alertas tempranas en zonas rurales de países en desarrollo que utiliza la arquitectura propuesta. El sistema cumple con los requisitos de reusabilidad, desarrollo basado en componentes, flexibilidad, interoperabilidad y utilización de tecnologías abiertas. Esta herramienta fue piloteada en el departamento del Cauca, en Colombia, en el marco de un proyecto de investigación y desarrollo financiado por la Comisión Europea

Un modelo de referencia para la especificación y análisis de Sistemas de Información para Vigilancia en Salud Pública

The specification of Health Information Systems is one of the more difficult stages in a software development project, especially when the development team has a limited knowledge about health care domain, because of the complexity of health business processes. The paper presents a reference model for the specification and analysis of Information systems for Public Health Surveillance. The aim of this model is to facilitate the design of the Requirements and Analysis Models defined in traditional software development processes. The usability of the model was demonstrated by supporting the requirements specification and analysis of a public health surveillance system in the Department of Cauca, Colombia. The proposed approach enhances the reusability and interoperability of final systems and it can be extended to any information system in a different domain.La especifiación de sistemas de información en el dominio de la salud es una de las tareas más difíciles dentro del proceso de desarrollo de este tipo de sistemas, debido principalmente al desconocimiento que normalmente tienen los equipos de desarrollo software acerca del dominio del problema y a la complejidad de los procesos de salud. El artículo presenta un Modelo de Referencia para la especificación y análisis de Sistemas de Información para Vigilancia en Salud Pública. El objetivo principal es facilitar el diseño de los modelos de Requerimientos y Análisis. La usabilidad del modelo es demostrada mediante el desarrollo de las etapas de especificación de requerimientos y análisis de un sistema de información para vigilancia en Salud Pública en el departamento del Cauca, Colombia. El modelo de referencia propuesto permite también la reusabilidad e interoperabilidad de los sistemas finales y puede ser extendido a otro tipo de sistemas de información

Refractive Properties of Binary Mixtures Formed by an Isomer of Chlorobutane and Butyl Ethyl Ether

Refractive indices of the binary mixtures containing an isomer of chlorobutane (1-chlorobutane, 2-chlorobutane, 2-methyl-1-chloropropane, or 2-methyl-2-chloropropane) and butyl ethyl ether have been measured at seven temperatures from T = 283.15 to 313.15 K From these data refractive index deviations were calculated and correlated with a Redlich-Kister polynomial expansion. The refractive index deviations were found positive. Finally, from these refractive indices both densities and surface tensions of the studied systems were predicted and compared with previously reported values

OEGMerge: un modelo de mezcla de ontologías basado en casuísticas

Desde hace tiempo la mezcla de ontologías es una actividad necesaria, sin embargo, los actuales métodos de mezcla de ontologías no tienen una casuística detallada ni una formalización precisa. Para la validación de estos métodos, es conveniente disponer de una casuística lo más completa posible. Por ello, en este artículo se presenta el modelo OEGMerge, desarrollado a partir de la experiencia del Grupo de Ingeniería Ontológica (OEG) de la UPM, en el que se describe detallada y formalmente la casuística de mezcla y las acciones a realizar en cada caso. En esta primera aproximación sólo se abarca taxonomía de conceptos, atributos y relacione