3,015 research outputs found
Residues of Correlators in the Strongly Coupled N=4 Plasma
Quasinormal modes of asymptotically AdS black holes can be interpreted as
poles of retarded correlators in the dual gauge theory. To determine the
response of the system to small external perturbations it is not enough to know
the location of the poles: one also needs to know the residues. We compute them
for R-charge currents and find that they are complex except for the
hydrodynamic mode, whose residue is purely imaginary. For different quasinormal
modes the residue grows with momentum q, whereas for the hydrodynamic mode it
behaves as a damped oscillation with distinct zeroes at finite q. Similar to
collective excitations at weak coupling the hydrodynamic mode decouples at
short wavelengths. Knowledge of the residues allows as well to define the time
scale t_H from when on the system enters the hydrodynamic regime, restricting
the validity of hydrodynamic simulations to times t>t_H.Comment: 10 pages, 3 figures, revtex4, v2: improved exposition and figure
Cirugía por toracoscopia videoasistida
La finalidad de este trabajo es reportar el gran auge que está tomando la llamada cirugía mínimamente invasiva en el campo de la cirugía torácica y nuestras primeras experiencias en el medio hospitalario de Mallorca. Este tipo de cirugía está viviendo un verdadero renacimiento gracias a la aplicación de microcámaras de vídeo a la toracoscopia tradicional y a la extensión de sus indicaciones y posibilidades por la creación de nuevo instrumental que posibilita la práctica de numerosas intervenciones en el tórax con un traumatismo quirúrgico mínimo. Hemos utilizado la videotoracoscopia en 10 pacientes con diferentes indicaciones y muy buenos resultados iniciales tanto diagnósticos como terapéuticos
Pescanova frente a la Soberanía Alimentaria
Contiene las notas "Rodaballos y Pescanova", de Manoel Santos (Revista Altermundo) y "España, sobrepesca y las grandes empresas", de Ocean Sentry.La pesca es una de las actividades humanas más antiguas y que más tiempo ha tardado en evolucionar. Sólo desde hace medio siglo se han empezado a introducir innovaciones tecnológicas con respecto a la actividad conocida desde hace milenios. Sin embargo, este último medio siglo está suponiendo una etapa convulsa que mantiene a la pesca enredada en grandes debates que enfrentan el sector. La pesca industrial, liderada por grupos como PESCANOVA, es un buen ejemplo de cómo los patrones de modernización en un entorno de mercados desregulados (en ocasiones de mercado ilegal) no se corresponden con las necesidades reales del planeta
The interaction between jets and clouds in the 3CR galaxies
From the HST/WFPC2 3CR Snapshot Survey, data taken with the filter F555W, F702W and narrow-ramp, a set of galaxies with noticeable extended structure were selected (e.g. 3C 79, 3C 135, 3C 234, etc). All of these objects show large regions of [OIII] λ 5007˚A emission (narrow ramp filter) and the broad-band filters data show similar structures indicating the presence of strong emission in several lines over these regions. The morphology observed seems to be related (e.g. same position angle, direct overlapping or similar shape) with the radio-jet. For some candidates with these properties GMOS/Gemini spectroscopy was taken. These data (both HST direct imaging and Gemini spectroscopy) can be tested with diagnostic diagrams and total UV photons budget to understand the source of energy that is ionizing the gas. This source of ionization was commonly believed to be the UV photons emitted by the powerful active galactic nuclei (AGN), but several of these objects show clearly that shocks produced by the radio jet are the main cause of the observed gas line emission. We show in this work, the results obtained over some of these radio-galaxies: 3C 135, 3C 180, 3C 234 and 3C 284.Fil: Hägele, G. F.. Universidad Autónoma de Madrid; EspañaFil: Feinstein Baigorri, Carlos. Universidad Nacional de La Plata. Facultad de Ciencias Astronómicas y Geofísicas; ArgentinaFil: Macchetto, D. F.. Space Telescope Science Institute; Estados UnidosFil: Montero, F.. Consejo Nacional de Investigaciónes Científicas y Técnicas. Oficina de Coordinación Administrativa Ciudad Universitaria. Instituto de Astronomía y Física del Espacio. - Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Instituto de Astronomía y Física del Espacio; Argentin
cSi Photovoltaic Modules, Main Degradation Factors Case Study: La Puna (Argentina)
This paper presents an analysis of the power loss of a set of photovoltaic modules exposed for more than fifteen years to solar radiation and other environmental factors. The study covered modules installed in 1989 and concluded with modules installed in 2004 (to 2009). Many of them were located in places high above the sea level and with high values of ultraviolet radiation. It is known that this power loss is caused by various factors: loss of optical properties of the protective glass, loss of transmittance of the encapsulation material (EVA), increase in series resistance, decrease in shunt resistance as well as other factors not analyzed in this study. The contribution of each of these factors to the power loss is measured and discussed in this analysis.Fil: Montero Larocca, María Teresa. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Salta. Instituto de Investigaciones en Energía no Convencional. Universidad Nacional de Salta. Facultad de Ciencias Exactas. Departamento de Física. Instituto de Investigaciones en Energía no Convencional; ArgentinaFil: Cadena, Carlos Alberto. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Salta. Instituto de Investigaciones en Energía no Convencional. Universidad Nacional de Salta. Facultad de Ciencias Exactas. Departamento de Física. Instituto de Investigaciones en Energía no Convencional; ArgentinaFil: Tamasi, Mariana Julia Luisa. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina. Comisión Nacional de Energía Atómica; Argentin
Torque distribution strategy for a four In-wheel fully electric car
Jornadas de Automática, 2 - 4 de septiembre de 2015. BilbaoElectromobility promises to have a strong impact
in several aspects of our life: introducing new
means of transport concepts, proposing new business models and allowing to create new vehicle
configurations impossible with traditional combustion engines. Regarding the latter, this paper
presents a novel torque distribution strategy for a
4 in-wheel electric vehicle which aims to reduce the
total longitudinal slip. The control strategy is designed off-line supported by a simulator and tested
both in simulation (with a different model from the
used for designing) as well as on a real sized prototype. The results show that the total longitudinal
slip is successfully reduced after applying the control strategy and additionally, the radius described
by the vehicle while cornering is slightly closer to
the theoretical Ackerman radius.Ministerio de Economía y Competitividad DPI2013-46912-C2-
Analysis and operational challenges of dynamic ride sharing demand responsive transportation models
There is a wide body of evidence that suggests sustainable mobility is not only a technological question, but that automotive technology will be a part of the solution in becoming a necessary albeit insufficient condition. Sufficiency is emerging as a paradigm shift from car ownership to vehicle usage, which is a consequence of socio-economic changes. Information and Communication Technologies (ICT) now make it possible for a user to access a mobility service to go anywhere at any time. Among the many emerging mobility services, Multiple Passenger Ridesharing and its variants look the most promising. However, challenges arise in implementing these systems while accounting specifically for time dependencies and time windows that reflect users’ needs, specifically in terms of real-time fleet dispatching and dynamic route calculation. On the other hand, we must consider the feasibility and impact analysis of the many factors influencing the behavior of the system – as, for example, service demand, the size of the service fleet, the capacity of the shared vehicles and whether the time window requirements are soft or tight. This paper analyzes - a Decision Support System that computes solutions with ad hoc heuristics applied to variants of Pick Up and Delivery Problems with Time Windows, as well as to Feasibility and Profitability criteria rooted in Dynamic Insertion Heuristics. To evaluate the applications, a Simulation Framework is proposed. It is based on a microscopic simulation model that emulates real-time traffic conditions and a real traffic information system. It also interacts with the Decision Support System by feeding it with the required data for making decisions in the simulation that emulate the behavior of the shared fleet. The proposed simulation framework has been implemented in a model of Barcelona’s Central Business District. The obtained results prove the potential feasibility of the mobility concept.Postprint (published version
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