9,689 research outputs found

    Integrated spectra extraction based on signal-to-noise optimization using Integral Field Spectroscopy

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    We propose and explore the potential of a method to extract high signal-to-noise (S/N) integrated spectra related to physical and/or morphological regions on a 2-dimensional field using Integral Field Spectroscopy (IFS) observations by employing an optimization procedure based on either continuum (stellar) or line (nebular) emission features. The optimization method is applied to a set of IFS VLT-VIMOS observations of (U)LIRG galaxies, describing the advantages of the optimization by comparing the results with a fixed-aperture, single spectrum case, and by implementing some statistical tests. We demonstrate that the S/N of the IFS optimized integrated spectra is significantly enhanced when compared with the single aperture unprocessed case. We provide an iterative user-friendly and versatile IDL algorithm that allows the user to spatially integrate spectra following more standard procedures. This is made available to the community as part of the PINGSoft IFS software package.Comment: Accepted for publication in Astronomy & Astrophysics, 12 pages, 7 figure

    Integral Field Spectroscopy based H\alpha\ sizes of local Luminous and Ultraluminous Infrared Galaxies. A Direct Comparison with high-z Massive Star Forming Galaxies

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    Aims. We study the analogy between local U/LIRGs and high-z massive SFGs by comparing basic H{\alpha} structural characteristics, such as size, and luminosity (and SFR) surface density, in an homogeneous way (i.e. same tracer and size definition, similar physical scales). Methods. We use Integral Field Spectroscopy based H{\alpha} emission maps for a representative sample of 54 local U/LIRGs (66 galaxies). From this initial sample we select 26 objects with H{\alpha} luminosities (L(H{\alpha})) similar to those of massive (i.e. M\ast \sim 10^10 M\odot or larger) SFGs at z \sim 2, and observed on similar physical scales. Results. The sizes of the H{\alpha} emitting region in the sample of local U/LIRGs span a large range, with r1/2(H{\alpha}) from 0.2 to 7 kpc. However, about 2/3 of local U/LIRGs with Lir > 10^11.4 L\odot have compact H{\alpha} emission (i.e. r1/2 < 2 kpc). The comparison sample of local U/LIRGs also shows a higher fraction (59%) of objects with compact H{\alpha} emission than the high-z sample (25%). This gives further support to the idea that for this luminosity range the size of the star forming region is a distinctive factor between local and distant galaxies of similar SF rates. However, when using H{\alpha} as a tracer for both local and high-z samples, the differences are smaller than the ones recently reported using a variety of other tracers. Despite of the higher fraction of galaxies with compact H{\alpha} emission, a sizable group (\sim 1/3) of local U/LIRGs are large (i.e. r1/2 > 2 kpc). These are systems showing pre-coalescence merger activity and they are indistinguishable from the massive high-z SFGs galaxies in terms of their H{\alpha} sizes, and luminosity and SFR surface densities.Comment: Accepted for publication in A&A. (!5 pages, 7 figures, 2 tables

    Immersion and invariance stabilization of nonlinear systems: A horizontal contraction approach

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    The main objective of this paper is to propose an alternative procedure to carry out one of the key steps of immersion and invariance stabilising controller design. Namely, the one that ensures attractivity of the manifold whose internal dynamics contains a copy of the desired system behaviour. Towards this end we invoke contraction theory principles and ensure the attractivity of the manifold rendering it horizontally contractive. The main advantage of adopting this alternative approach is to make more systematic the last step of the design with more explicit degrees of freedom to accomplish the task. The classical case of systems in feedback form is used to illustrate the proposed controller design.This work is partially supported by National Basic Research Program of China (973 Program 2013CB035406) ; National Natural Science Foundation of China (NSFC: 61134007 and 61320106009).This is the author accepted manuscript. The final version is available from IEEE via http://dx.doi.org/10.1109/CDC.2015.740268

    Magnetoelectric Effect in Type-II Quantum Cone Induced by Donor Impurity

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    We consider a model of donor centered at the base of a type-II nanocone, in which the excessive electron, released from the donor, is located within a narrow tube-shaped shell exterior region around the cone lateral surface. By solving the one-electron Schrödinger equation we analyze the alteration of the spatial probability distribution of the electron, the period of the Aharonov-Bohm oscillations of the energy levels, and the electric and magnetic moments induced by external electric and magnetic fields, applied along the symmetry axis. We show that the diamagnetic confinement provided by the magnetic field forces the electron to climb along the cone’s border, inducing the electric polarization of the structure. Similarly, the external electric field, which pushes the electron toward cone’s bottom, changes the order of the energy levels with different magnetic momenta varying the magnetic polarization of the structure. Our theoretical analysis reveals a new possibility for the coupling between the polarization and magnetization arising from the quantum-size effect in type-II semiconductor nanocones

    Management Models in SMEs, Strategic Tool in Business Management

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    The business sector constitutes an engine for the Ecuadorian economy through the generation of employment and redistribution of wealth. Therefore, given the current economic dynamics of high competition, globalization of markets, and use of information and communication technologies, business managers need to use different tools such as management models to achieve acceptable levels of utility, profitability, customer satisfaction and permanence in the consumer market. This research involved an analysis of the impact on corporate management of applying different management models of Small and Medium Enterprises (SMEs) in the city of Riobamba, province of Chimborazo (Ecuador). The study was descriptive, cross-sectional, exploratory and non-experimental and it was conducted in the first half of 2019. Data were collected through field investigation and the application of a structured survey with a sample composed of 136 managers, owners and administrators, from a population of 440 entrepreneurs. The results showed that 93% of entrepreneurs knew about the existence of management models, and 41% recorded that total quality is the most applied model followed by continuous improvement (18%) and re-engineering (13%). We conclude that entrepreneurs consider management models to be crucial in the management of their company. Keywords: management model, business management, strategies, competitiveness, SMEs. Resumen El sector empresarial en todos sus niveles constituye un motor para la economía ecuatoriana, por la generación de empleo y redistribución de la riqueza; por ello los gerentes de las empresas dada la actual dinámica económica por la alta competencia, globalización de los mercados, uso de las tecnologías de información y comunicación, entre otras variables, necesita utilizar diferentes herramientas como son los modelos gerenciales para lograr niveles aceptables de utilidad, rentabilidad, satisfacción de los clientes y permanencia en el mercado consumidor. La investigación tiene como objetivo efectuar un análisis de la aplicación e incidencia en la gestión corporativa, de diferentes modelos gerenciales de las Pequeñas y Medianas empresas (Pymes) de la ciudad de Riobamba, provincia de Chimborazo (Ecuador). El estudio es descriptivo, transversal, exploratorio y no experimental efectuado en el primer semestre del año 2019, realizado mediante una investigación de campo, a través de la aplicación de una encuesta estructurada, seleccionando una muestra compuesta por 136 gerentes, propietarios y administradores, de una población de 440 empresarios. Los resultados obtenidos evidenciaron que el 93% de los empresarios conocen de la existencia de modelos gerenciales, el 41% registra que la calidad total es el modelo más aplicado seguido del mejoramiento continuo (18%) y Reingeniería (13%). Se concluye que los empresarios y emprendedores consideran a los modelos gerenciales de mucha importancia en la dirección de su empresa. Palabras clave: modelo gerencial, gestión empresarial, estrategias, competitividad, pymes

    Fabrication of biodegradable synthetic vascular networks and their use as a model of angiogenesis

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    One of the greatest challenges currently faced in tissue engineering is the incorporation of vascular networks within tissue-engineered constructs. The aim of this study was to develop a technique for producing a perfusable, three-dimensional cell friendly model of vascular structures that could be used to study the factors affecting angiogenesis and vascular biology in engineered systems in more detail. Initially, biodegradable synthetic pseudo-vascular networks were produced via the combination of robocasting and electrospinning techniques. The internal surfaces of the vascular channels were then recellularized with human dermal microvascular endothelial cells (HDMECs) with and without the presence of human dermal fibroblasts (HDFs) on the outer surface of the scaffold. After 7 days in culture, channels that had been reseeded with HDMECs alone, demonstrated irregular cell coverage. However when using a co-culture of HDMECs inside and HDFs outside the vascular channels, coverage was found to be continuous throughout the internal channel. Using this cell combination, collagen gels loaded with vascular endothelial growth factor were deposited onto the outer surface of the scaffold and cultured for a further 7 days after which endothelial cell (EC) outgrowth from within the channels into the collagen gel was observed showing the engineered vasculature maintains its capacity for angiogenesis. Furthermore the HDMECs appeared to have formed perfusable tubules within the gel. These results show promising steps towards the development of an in vitro platform upon which to study angiogenesis and vascular biology in a tissue-engineering context

    New molecular tool for a quick and easy detection of apple scab in the field

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    Venturia inaequalis, an agent of apple scab, is the most important pathogen of Malus x domestica. Control measures against this pathogen rely on intensive phytosanitary programs based on predictive models to identify the meteorological conditions conducive to the primary infection. The detection of the pathogen in field, both in naturally infected symptomatic and asymptomatic leaves, is desirable. Loop-mediated isothermal amplification (LAMP) assays are profitable molecular diagnostic tools for the direct detection of pathogens in field. A LAMP assay for V. inaequalis has been designed on the elongation factor 1-alpha sequence. The validation of the LAMP assay was carried out following the international EPPO standard PM 7/98 in terms of specificity, sensitivity, repeatability and reproducibility. Specificity testing was performed using target and non-target species, such as phylogenetically related Venturia species and other pathogens commonly found in apple, resulting in positive amplification only for the target with a time to positive ranging from 20 to 30 min. Sensitivity testing was performed with serial dilutions of DNA of the target and by artificial inoculation of young apple leaves. The reliability of the LAMP assay as an early-detection tool and its user-friendly application make it suitable for the diagnosis of apple scab in the field
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