1,030 research outputs found

    Optimization method for the determination of material parameters in damaged composite structures

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    An optimization method to identify the material parameters of composite structures using an inverse method is proposed. This methodology compares experimental results with their numerical reproduction using the finite element method in order to obtain an estimation of the error between the results. This error estimation is then used by an evolutionary optimizer to determine, in an iterative process, the value of the material parameters which result in the best numerical fit. The novelty of the method is in the coupling between the simple genetic algorithm and the mixing theory used to numerically reproduce the composite behavior. The methodology proposed has been validated through a simple example which illustrates the exploitability of the method in relation to the modeling of damaged composite structures.Peer ReviewedPostprint (author’s final draft

    Kinematic study of planetary nebulae in NGC 6822

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    By measuring precise radial velocities of planetary nebulae (which belong to the intermediate age population), H II regions, and A-type supergiant stars (which are members of the young population) in NGC 6822, we aim to determine if both types of population share the kinematics of the disk of H I found in this galaxy. Spectroscopic data for four planetary nebulae were obtained with the high spectral resolution spectrograph Magellan Inamori Kyocera Echelle (MIKE) on the Magellan telescope at Las Campanas Observatory. Data for other three PNe and one H II region were obtained from the SPM Catalog of Extragalactic Planetary Nebulae which employed the Manchester Echelle Spectrometer attached to the 2.1m telescope at the Observatorio Astron\'omico Nacional, M\'exico. In the wavelength calibrated spectra, the heliocentric radial velocities were measured with a precision better than 5-6 km s−1^{-1}. Data for three additional H II regions and a couple of A-type supergiant stars were collected from the literature. The heliocentric radial velocities of the different objects were compared to the velocities of the H i disk at the same position. From the analysis of radial velocities it is found that H II regions and A-type supergiants do share the kinematics of the H I disk at the same position, as expected for these young objects. On the contrary, planetary nebula velocities differ significantly from that of the H I at the same position. The kinematics of planetary nebulae is independent from the young population kinematics and it is closer to the behavior shown by carbon stars, which are intermediate-age members of the stellar spheroid existing in this galaxy. Our results are confirming that there are at least two very different kinematical systems in NGC 6822

    El turismo micológico como fuente de ingresos y empleo en el medio rural. El caso de Castilla y León

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    Edible wild mushroom picking is becoming an important source of income in rural areas. The wide range of activitieswhich add value to mycological production (initial sale, transformation, marketing, etc.) include those related to tourismwhich can attract visitors to mushroom producing areas, leading to so-called mycological tourism. To date, no researchexists quantifying the importance thereof in rural areas endowed with such resources. The present research provides thefirst model to estimate this activity’s contribution to the economy of rural areas in the region of Castilla y León. The mainfinding to emerge evidences a close link between influx of visitors, who come principally to pick, and mycological productivityin the region. Based on this relation, we estimate four key variables to determine the impact which said activityhas on the regional economy as a whole: the number of overnight stays and trips made by mycological tourists, as wellas associated expenditure and employment created. Findings underscore the importance of this activity in the regionaltourism industry and point to its significance as a major market niche, particularly during the hotel low season. The needfor public administrators to implement a related management policy is also inferred. La recolección de hongos silvestres comestibles se está convirtiendo en un importante motor generador de rentasen el medio rural. Entre las variadas actividades que aportan valor a la cadena de producción, relacionadas con la micología (primera venta, transformación, comercialización, etc.), se encuentran aquellas de turismo capaces de atraer visitantes a los territorios productores o turismo micológico. En la actualidad no existe ninguna investigación que cuantifique su importancia en las áreas rurales con recurso. Así, en la presente investigación se desarrolla por primera vez un modelo, que se aplica para estimar esta aportación a la economía de los territorios rurales de la comunidad autónoma de Castilla y León. El principal hallazgo obtenido muestra que existe una fuerte relación entre afluencia de visitantes, cuya principal motivación es recolectar, y la productividad micológica del territorio. A partir de esta relación se estiman cuatro variables fundamentales para calcular la importancia de esta actividad en el total de esta economía: el número de pernoctaciones y de viajes realizados por turistas micológicos, así como el gasto asociado y el empleo generado. Los resultados expuestos muestran la importancia relativa de esta actividad sobre el sector del turismo rural en la región, lo que la convierte en un importante nicho de mercado de vital importancia, sobre todo en temporadas de baja ocupación de los establecimientos hoteleros, lo que hace necesario políticas de gestión de esta actividad por parte de las administraciones públicas.

    Strategic planning for community sustainability in model forests: Case study of the Yoro model forest, Honduras

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    El estudio plantea una planificación estratégica de desarrollo en los Bosques Modelo a partir del estudio del caso del Bosque Modelo de Yoro, en Honduras, en donde el sector de la industria maderera y en concreto el subsector de carpintería y mueble, parece tener más ventajas competitivas para producir productos de exportación que generen riqueza en la zona, dada la escasa capacidad de compra de la región. A este subsector se le realiza un Análisis estratégico, una Elección estratégica y una Implementación estratégica determinando que el desarrollo del subsector podría pasar por crear una cooperativa capaz de suministrar partes de muebles a una empresa de carácter internacional que tenga como estrategia comercial la venta de muebles naturales, ecológicos y que esté comprometida socialment

    A gain-scheduled LPV control for oxygen stoichiometry regulation in PEM fuel cell systems

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    The article addresses the LPV control of a Polymer Electrolyte Membrane Fuel Cell (PEMFC). In order to optimize efficiency, PEMFCs require reliable control systems ensuring stability and performance, as well as robustness to model uncertainties and external perturbations. On the other hand, PEMFCs present a highly nonlinear behavior that demands nonlinear and/or adaptive control strategies to achieve high performance in the entire operating range. Here, a linear parameter varying (LPV) gain scheduled control is proposed. The control is based on a piecewise affine LPV representation of the PEMFC, a model that can be available in practice. In order to deal with the saturation of the control action, an LPV anti-windup compensation is also proposed. The complete control strategy is applied to several experimental practical situations in a laboratory fuel cell system to evaluate its performance and the reliability of the proposed algorithms.The research of F.D. Bianchi was supported by the European Regional Development Funds (ERDF, FEDER Programa Competitivitat de Catalunya 2007-2013). The research of C. Kunusch has been supported by the Seventh Framework Programme of the European Community through the Marie Curie actions (GA: PCIG09-GA-2011-293876) and project Puma-Mind (GA: FCH-JU-2011-1-303419), as well as by the CICYT project DPI2011-25649 (MICINN-Spain). The research of C. Ocampo-Martinez has been supported by the project MACPERCON (Ref. 201250E027) of the CSIC. The research of R.S. Sánchez Peña has been supported by CONICET and grant PICT2008-290 from the PRH Program of the Ministry of Science, Technology and Innovation of Argentina.Peer Reviewe

    Association Between Medication Adherence and Oxidative Stress in Patients With First-Episode Mania

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    Poor adherence is a major problem in patients with manic episodes that impairs functionality and has unknown effects on oxidative stress. The objective of this study was to analyze the relationship between adherence to medication, severity of symptoms and oxidative stress in a sample of patients with a first episode of mania. A longitudinal, 6-month study was performed in 60 patients, who were classified as adherent and non-adherent to medication (mainly antipsychotics). Blood levels of oxidative stress parameters and expression of the antioxidant nuclear transcription factor NRF2 in mononuclear cells of peripheral blood were assessed at baseline and at the end of follow-up. In addition, clinical symptoms and functioning were evaluated. Linear multivariate regression was used to determine the relationship between adherence, oxidative stress, and clinical symptoms. Finally, 44 patients completed follow-up. The results of this study showed that at 6-month follow-up, adherence was significantly associated with better functioning and reduced clinical symptoms. Additionally, more severe symptoms were associated with increased levels of oxidative stress and antioxidant parameters. At study completion, non-adherents exhibited greater levels of antioxidants than adherent patients. In conclusion, poor adherence to medication is associated with a poorer prognosis in the medium term and causes increased antioxidant response.This study has been funded by Instituto de Salud Carlos III through the projects PI12/02077, PI16/01164, PI14/01900 (Co-funded by European Regional Development Fund/European Social Fund. Investing in your future); the Basque Foundation for Health Innovation and Research (BIOEF); Networking Center for Biomedical Research in Mental Health (CIBERSAM) and the University of the Basque Country (GIC12/84). The psychiatric research department in University Hospital Araba is supported by the Stanley Research Foundation (03-RC-003). SG has a PhD fellowship from the University of the Basque Country

    The first Hochschild cohomology group of a schurian cluster-tilted algebra

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    Given a cluster-tilted algebra B we study its first Hochschild cohomology group HH1(B) with coefficients in the B-B-bimodule B. We find several consequences when B is representation-finite, and also in the case where B is cluster-tilted of type Ã.Fil: Assem, Ibrahim. University of Sherbrooke; CanadáFil: Redondo, Maria Julia. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Bahía Blanca. Instituto de Matemática Bahía Blanca. Universidad Nacional del Sur. Departamento de Matemática. Instituto de Matemática Bahía Blanca; Argentin

    Parathyroid hormone-related protein as a renal regulating factor: From Vessels to Glomeruli and Tubular Epithelium

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    Parathyroid hormone (PTH) and PTH-related protein (PTHrP) produce similar biological effects through the PTH/PTHrP receptor. Less is known about the physiological role of PTHrP, which was first identified as the agent of the humoral hypercalcemia of malignancy. Despite the widespread production of PTHrP in healthy individuals, the concentration of the protein is below the detectable limit of current assays, suggesting that PTHrP normally functions locally in an autocrine or paracrine manner. Thus, some differences in their biological activities have been described and they may be related to the presence of different receptors. In this regard, a second receptor that binds selectively to PTH has also been found. Recent studies have demonstrated the expression of both PTH/PTHrP receptor and protein in the renal glomeruli. Moreover, there are convincing data that support a direct role of PTH and PTHrP in modulating renal blood flow and glomerular filtration rate. This multifunctional protein, PSHrP, also has a proliferative effect on both glomerular mesangial cells and tubular epithelial cells. Increases in the expression of PTHrP have been observed in several experimental models of nephropathies, suggesting that PTHrP upregulation is a common event associated with the mechanism of renal injury and repair
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