Detection of a Super Star Cluster as the Ionizing Source in the Low Luminosity AGN NGC 4303

HST UV STIS imaging and spectroscopy of the low luminosity AGN (LLAGN) NGC 4303 have identified the previously detected UV-bright nucleus of this galaxy, as a compact, massive and luminous stellar cluster. The cluster with a size (FWHM) of 3.1 pc, and an ultraviolet luminosity log L (1500 A}(erg/s/A)= 38.33 is identified as a nuclear super star cluster (SSC) like those detected in the circumnuclear regions of spirals and starburst galaxies. The UV spectrum showing the characteristic broad P Cygni lines produced by the winds of massive young stars, is best fitted by the spectral energy distribution of a massive cluster of 1e5 Msol generated in an instantaneous burst 4 Myr ago. No evidence for an additional non-thermal ionizing source associated with an accreting black hole is detected in the ultraviolet. We hypothesize that at least some LLAGNs in spirals could be understood as the result of the combined ionizing radiation emitted by an evolving SSC and a black hole (BH) accreting with low radiative efficiency, coexisting in the inner few parsecs region.Comment: 4 figure

Numerical simulation of vortex-induced vibrations of a pair of cylinders

The 2-D numerical simulation of vortex-induced vibrations of twocloselyspaced parallel rigid circular cylinders, restrained by elastic springs and aligned in a normal direction with respect to the free stream flow, is presented in this work. Fluid-structure interaction is taken into account by a strong coupling based in equilibrium and compatibility conditions at the interfaces. A moving mesh, adjustable to the motion of the bodies, is included using an Arbitrary Lagrangean-Eulerian (ALE) description

Modelling of Multi-terminal VSC-HVDC Links for Power Flows and Dynamic Simulations of AC/DC Power Networks

Power transmission systems are expanded in order to supply electrical energy to remote users, to strengthen their operational security and reliability and to be able to carry out commercial transactions with neighbouring power grids. Power networks successfully expand, at any time, by incorporating the latest technological developments. A case in point is the current growth of electrical power grids, in terms of both infrastructure and operational complexity, to meet an unprecedented upward trend in global demand for electricity. Today’s expansion of the power grid is being supported, more and more, by power electronics, in the form of flexible AC transmission systems and HVDC systems using voltage-sourced converters. The latter option, in particular, has been developing exceedingly rapidly since 1999, when the first commercial VSC- HVDC transmission installation was commissioned; the voltage -sourced converter technology has become the preferred option for transporting electricity when natural barriers are present (e.g. the sea), in Europe and further afield. At least one influential European body has recommended that the next step in the construction of the so-called European super grid, be a meshed HVDC transmission system based on the use of the VSC technology, to facilitate further the massive incorporation of renewable energy sources into the Pan European electrical grid, the harvesting of hydrocarbons that lie in deep sea waters and the energy trading between neighbouring countries.It is in this context that this thesis contributes new knowledge to the modelling of VSC-based equipment and systems for the assessment of steady-state and transient stability analyses of AC/DC power networks. The STATCOM, the back-to -back VSC-HVDC link, the point-to-point VSC-HVDC link and the multi-terminal VSC- HVDC link, all receive research attention in this work. The new models emanating from this research capture all the key steady-state and dynamic characteristics of the equipment and network. This has required a paradigm shift in which the VSC equipment has been modelled, here-to-fore, assuming that a voltage-sourced converter behaves like an idealised voltage source. In contrast, the models developed in this research resort to an array of basic power systems elements, such as a phase-shifting transformer and an equivalent shunt susceptance, giving rise to a two-port circuit where the AC and DC sides of the VSCs are explicitly represented. The ensuing VSC model is fundamentally different from the voltage source model; it represents, in an aggregated manner, the array of semiconductor switches in the converter and its PWM control. The VSC model was used as the basic building block with which to develop all the VSC-base d devices put forward in this thesis. The ultimate device is the multiterminal VSC-HVDC system, which may comprise an arbitrary number of VSC units commensurate with the number of otherwise independent AC sub-networks and a DC network of an arbitrary topology. The steady -state and dynamic simulations of the AC/DC systems are carried out using a unified frame-of-reference which is amenable to the Newton-Raphson algorithm. This framework accommodates, quite naturally, the set of discretised differential equations arising from the synchronous generators, HVDC and FACTS equipment, and the algebraic equations describing the conventional transmission lines, transformers and loads of the AC sub-networks. The application areas covered in this work are: power-flow studies and dynamic simulations

Heterochromia Iridium Congénita: De clínica al diagnóstico

Galería Fotográfica (sin resumen)&nbsp

Design of the strategic direction for the company Eventos 1A Recreación y Turismo SAS of the city of Duitama Boyacá

La empresa Eventos 1A Recreación y Turismo S.A.S es una empresa Boyacense que presta los servicios en actividades de bienestar empresarial, mercadeo BTL, producción y organización de eventos y turismo, la cual requiere establecer una planificación estratégica de acuerdo a los continuos cambios del mercado y las exigencias de la competitividad. Un diseño del direccionamiento estratégico permitirá encaminar a la organización hacia la prestación de un mejor servicio, posicionarse en el sector y conocer mejor la organización para que el proceso de toma de decisiones sea efectivo integrando las áreas de la empresa. El objetivo general es elaborar la propuesta de intervención enfocada en el diseño del direccionamiento estratégico para la empresa Eventos 1A Recreación y turismo S.A.S. de la ciudad de Duitama Boyacá, para lograr este objetivo se plantea realizar el diagnóstico de la situación actual de la empresa en lo referente a la gestión estratégica mediante un análisis del microentorno, macroentorno e interno; construir un marco de referencia alrededor de los modelos de gestión estratégica como PEST, Matriz EFAS, MMGO (Modelo de modernización para la gestión de organizaciones), 5 fuerzas de Porter, Matriz IFAS, Prospectiva Estratégica (escenarios), Matriz Dofa y Cuadro de Mando Integral; diseñar estrategias del direccionamiento estratégico y elaborar un plan de acción para las estrategias diseñadas. El tipo de investigación fue descriptivo, con enfoque cualitativo. Se hizo uso de entrevista a directivos, empleados, clientes, proveedores y empresas competidoras cuya información se plasma en las herramientas de administración estratégica.The company Eventos 1A Recreación y Turismo S.A.S is a Boyacense company that provides services in business wellness activities, BTL marketing, production and organization of events and tourism, which requires establishing strategic planning according to continuous market changes and the demands of the competitiveness. A design of the strategic direction will allow the organization to be directed towards providing a better service, positioning itself in the sector and getting to know the organization better so that the decision-making process is effective integrating the areas of the company. The general objective is to prepare the intervention proposal focused on the design of the strategic direction for the company Eventos 1 A Recreación y turismo S.A.S. from the city of Duitama Boyacá, in order to achieve this objective, a diagnosis of the current situation of the company in relation to strategic management is proposed, through an analysis of the macro, micro and internal environments; build a frame of reference around strategic management models such as PEST, EFAS Matrix, MMGO (Modernization Model for Organizational Management), Porter's 5 Forces, IFAS Matrix, Strategic Prospective (scenarios); Dofa Matrix and Balanced Scorecard; design strategies of the strategic direction and elaborate an action plan for the designed strategies. The type of research was descriptive, with a qualitative approach. An interview was used with managers, employees, clients, suppliers and competing companies whose information is reflected in the strategic management toolsMagíster en Administración de Empresas - MB

La relación entre ventajas competitivas y resultados empresariales en la industria agroalimentaria aragonesa

Este trabajo investiga la relación entre las ventajas competitivas y resultados empresariales en el marco de la industria agroalimentaria (IAA) en Aragón (España). Se propone un modelo de ecuaciones estructurales cuyas relaciones se construyen teniendo en cuenta la literatura existente sobre el tema tanto en su vertiente teórica como empírica. Sobre una muestra de 194 empresas agroalimentarias aragonesas y un total de 19 indicadores, seleccionados para inferir las ventajas competitivas empresariales, se ha utilizado la técnica de Partial Least Squares (PLS) para contrastar las relaciones estructurales. La importancia de las actividades de innovación, introducción de nuevos productos y relaciones con los proveedores sobresalen sobre otros tipos de actividades y confirman cuatro de las siete hipótesis enunciadas.Industria agroalimentaria (IAA), Aragón, ventajas competitivas, Modelo de Ecuaciones Estructurales (MEE), Agricultural and Food Policy, C31, C51, L66, R10,

Association between chloroplast DNA and mitochondrial DNA haplotypes in Prunus spinosa L. (Rosaceae) populations across Europe

Chloroplast DNA (cpDNA) and mitochondrial DNA (mtDNA) were studied in 24 populations of Prunus spinosa sampled across Europe. The cpDNA and mtDNA fragments were amplified using universal primers and subsequently digested with restriction enzymes to obtain the polymorphisms. Combinations of all the polymorphisms resulted in 33 cpDNA haplotypes and two mtDNA haplotypes. Strict association between the cpDNA haplotypes and the mtDNA haplotypes was detected in most cases, indicating conjoint inheritance of the two genomes. The most frequent and abundant cpDNA haplotype (C20; frequency, 51 %) is always associated with the more frequent and abundant mtDNA haplotype (M1; frequency, 84 %). All but two of the cpDNA haplotypes associated with the less frequent mtDNA haplotype (M2) are private haplotypes. These private haplotypes are phylogenetically related but geographically unrelated. They form a separate cluster on the minimum-length spanning tree.We thank Dr Remy J. Petit for providing significant support as a coordinator during this project, and for helpful suggestions and valuable comments on the manuscript. The research was supported by the European Community research programme FAIR5‐CT97‐3795

From Microscopic to Macroscopic Description of Composite Thin Panels: A Roadmap for their Simulation in Time Domain

In this paper, we show a simulation strategy for composite dispersive thin-panels, starting from their microscopic characteristics and ending into a time-domain macroscopic model. In a first part, we revisit different semianalytic methods that may be used to obtain the S-parameter matrices. The validity of them is assessed with numerical simulations and experimental data. We also include some formulas that may be used to tailor the shielding effectiveness of panels in a design phase. In a second part, we present an extension to dispersive media of a subgridding hybrid implicit–explicit algorithm finite difference time domain (FDTD) devised by the authors to deal with that kind of materials. The method, here presented and applied to the FDTD method, is a robustly stable alternative to classical impedance boundary condition techniques. For this, a previous analytical procedure allowing to extract an equivalent effective media from S-parameters is presented, thus making this road map able to simulate any kind of dispersive thin layer. A numerical validation of the algorithm is finally shown by comparing with experimental data