9,247 research outputs found
Revisiting the dynamics of catastrophic late Pleistocene glacial-lake drainage, Altai Mountains, central Asia
In this work, we present a whole system model of megafloods from catastrophic ice-dam failure in the late Pleistocene that comprises the study of the dynamics of the glacial lake, the propagation of the flood wave downstream of the dam, and an approximation to the ice breach process. The ice-dam incision rate was simply considered an unknown constant, which was varied systematically to best fit the maximum altitude of the simulated water surface and the paleostage indicators in the downstream valley during the transient megaflood. Hence, the hydrograph resulting from the breach of the ice dam was not prescribed but was an output of the paleohydraulic reconstruction.
By considering two possible configurations of the breach in the ice dam, i.e. full or partial removal of the ice, we constrained the incision rate in the narrow range of 28 − 42 m ⋅ h−1. Two connected glacial lakes, Kuray and Chuja, released 95% of the stored water volume (i.e., 564 km3) in 33.8 hours. A peak discharge of 10.5 M m3 ⋅ s−1 was required to form numerous giant bars and run-up deposits in the Chuja and Katun valleys. The peak streamflow occurred after 11 h when 45% of the available lake volume had been evacuated from the Kuray and Chuja basins. Further verification of the reconstructed megaflood was achieved by studying the computed hydraulic conditions during the lake draining that justify the existence and orientation of several fields of subaqueous gravel-dunes in the glacial lake. Complex spatiotemporal patterns during the recession stage of the flood built most of the fields of bedforms. In terms of nondimensional parameters, the Froude and Shields numbers that formed the dune fields were similar to those observed in large sandy rivers, but the flow was undoubtedly unsteady and two-dimensional.
We conclude by noting that the extensions of the simulated area cannot be cropped or analysed by independent parts in order to predict the formation of the most relevant geological records due to the unsteady, two-dimensional nature of the flow motion and the development of backwater effects in the drainage network. Lastly, the paleohydrological reconstruction of a megaflood has helped not only to infer the dynamics of the event but also to retrodict the mean parameters of the ice-dam failure mechanism.This work was supported by the Spanish Ministry of Science, Innovation and Universities (MICINN/FEDER, UE) under Grant SEDRETOCGL2015-70736-R. P.R.J. was supported by the European Social Fund and the University of Jaén
Irregular self-similar configurations of shock-wave impingement on shear layers
An oblique shock impinging on a shear layer that separates two uniform supersonic streams, of Mach numbers M1 and M2, at an incident angle σi can produce regular and irregular interactions with the interface. The region of existence of regular shock refractions with stable flow structures is delineated in the parametric space (M1,M2,σi) considering oblique-shock impingement on a supersonic vortex sheet of infinitesimal thickness. It is found that under supercritical conditions, the oblique shock fails to deflect both streams consistently and to provide balanced flow properties downstream. In this circumstance, the flow renders irregular configurations which, in the absence of characteristic length scales, exhibit self-similar pseudosteady behaviours. These cases involve shocks moving upstream at constant speed and increasing their intensity to comply with equilibrium requirements. Differences in the variation of propagation speed among the flows yield pseudosteady configurations that grow linearly with time. Supercritical conditions are described theoretically and reproduced numerically using highly resolved inviscid simulation
La hipnosis en psicología del deporte
En este trabajo efectuamos un encuadre de la intervención hipnosugestiva en el ámbito de la psicología del deporte, a través de una revisión crítica de trabajos representativos en distintas facetas de la disciplina. Se hace énfasis en la necesidad de consensuar algunas premisas teóricas que permitan un entendimiento y una aplicación de la hipnosis al deporte de manera justa y objetiva. Finalmente, partiendo de una propuesta conceptual sobre la hipnosis, se apuntan algunas ideas básicas sobre el manejo de la sugestión en el entrenamiento de las principales variables psicológicas relevantes para la ejecución deportivaIn this work, hypnosuggestive intervention will be delt with within the frame of sports psychology. A critical revision of some representative works in the different aspects of this discipline will be used to achieve this goal. We will emphasize the need for a consensus in some thoretical premises that could lead us to a better understanding of hypnosis in sports and allow us to use it in a fair and objective way. Finally, from a conceptual proposal about hypnosis, some new basic ideas about how to use suggestion in the training of the most important psychological variables which are relevant to sports performance will be put forwar
Lente de contacto híbrida de geometría inversa en córnea irregular con presencia de isla central tras cirugía LASIK
La lente híbrida de geometría inversa PS ofrece una mejoría de la calidad visual en pacientes con córneas irregulares tras cirugía refractiva miópica, mostrándose como una excelente opción en aquellos casos en que el insuficiente lecho corneal imposibilita retratamientos posteriores
Método de Prospección y Caracterización de materias primas
Número de publicación: ES2341697 A1 (24.06.2010)También publicado como: ES2341697 B2 (26.04.2011)Número de Solicitud: Consulta de Expedientes OEPM (C.E.O.) P200803674(23.12.2008)Método de prospección y caracterización geológica de materias primas. El método objeto de la invención consiste en el uso de un sistema SIG para la gestión y utilización de datos obtenidos previamente almacenados en medios de almacenamiento de datos conformando bases de datos independientes que son fusionadas y cuyo resultado es trasferido al sistema SIG para representar las localizaciones y materias primas que se encuentran en dicha ubicación elegida o viceversa.Universidad de Almerí
Impulse Control Disorders and Dopamine-Related Creativity: Pathogenesis and Mechanism, Short Review, and Hypothesis
Impulse control disorder (ICD), including pathological gambling, hypersexuality, and compulsive shopping has been linked to antiparkinsonian medication, especially dopamine agonists. The mechanism of ICD is not completely clear, but it seems that ICD is the result of an activation of dopamine receptors, mostly D3 in the ventral striatum. Patients treated with dopamine agonists that have preferential affinity for D3 (including ropinirole and pramipexole) are much more prone to develop ICD. In addition, a genetic component is probably present, especially in young patients. Finally, environment and lifestyle may also play a role: those patients engaged in physical, social, and artistic activities are probably less likely to develop ICD compared to those patients with poor physical activity living in isolated environments
VNUML vs GNS3 en el desarrollo de laboratorios de redes virtuales
El aprendizaje práctico de redes de computadores
es reconocido como un proceso crítico que permite
a los estudiantes consolidar los conceptos introducidos
en las lecciones teóricas. En este sentido, las
tecnologías de virtualización están adquiriendo gran
relevancia debido a que permiten desarrollar laboratorios
de redes de computadores con un reducido
coste de despliegue y gestión. Este artículo presenta
un análisis comparativo entre GNS3 y VNUML, que
son herramientas de virtualización open-source que
han sido empleadas para el desarrollo de laboratorios
de red virtuales para llevar a cabo el proceso de
enseñanza-aprendizaje en las asignaturas Arquitectura
de Redes y Arquitectura de Redes Avanzadas
del Grado en Ingeniería Informática impartido en la
Universidad de Murcia. El estudio presenta las principales
ventajas y/o deficiencias de cada herramienta
tanto para profesores como alumnos y se identifican
los escenarios en los que parece más adecuada su
utilización.SUMMARY -- The practical learning of computer networks is
known to be a critical process in order to allow
students to consolidate the concepts introduced in
theoretical lessons. In this sense, virtualization technologies
are becoming popular since they allow
to set up a computer network laboratory with a reduced
deployment and management cost. This paper
presents a comparative analysis performed between
GNS3 and VNUML, which are open-source
tools for virtualization that have been used for developing
virtual network laboratories that support the
teaching-learning process in the Networks Architecture
and Advanced Networks Architecture subjects
of the Computer Engineering degree at the University
of Murcia. The study presents the main advantages
and/or deficiencies of each tool not only for professors
but also for students and identifies the scenarios
where the use of each tool seems to be more
appropriate.Peer Reviewe
Regresión no lineal mediante la evolución de modelos Híbridos de Redes Neuronales
El presente trabajo es una primera aproximación a
la formación de modelos de redes neuronales con
unidades ocultas de tipo híbrido (sigmoides,
producto) que siendo aproximadores universales,
puedan utilizarse como modelos no lineales de
regresión cuando las características del espacio de
las variables independientes lo aconsejen. Dada la
dificultad que presenta la aplicación de algoritmos
de aprendizaje de búsqueda local para esta
tipología de modelos, se utiliza un algoritmo de
programación evolutiva donde se definen
operadores de mutación específicos. Los
experimentos realizados con cuatro funciones de
prueba, las tres funciones de Friedman y una
propuesta por los autores, muestran resultados
muy prometedores en esta direcció
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