1,579 research outputs found

    Dynamic Kinetic Resolution of Hetero biaryl Ketones by Zinc- Catalyzed Asymmetr ic Hydrosil ylation

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    Adiastereo- and highly enantioselective dynamic kinetic resolution (DKR) of configurationally labile hetero- biaryl ketones is described. The DKR proceeds by zinc- catalyze dhydrosilylation of the carbonyl group ,thus leading to secondary alcohols bearing axial and central chirality .The strategy relies on the labilization of the stereogenic axis that takes place thanks to aLewis acid–base interaction between anitrogen atom in the heterocycle and the ketone carbonyl group .The synthetic utility of the methodology is demonstrated through stereospecific transformations into either N,N-ligands or appealing axially chiral, bifunctional thiourea organocata- lysts.Ministerio de Ciencia e Innovación (Grants CTQ2016-76908-C2-1-P, CTQ2016-76908-C2-2-P, contract RYC-2013-12585)European FEDER FundsJunta de Andalucía (Grant 2012/FQM 10787)European Union - Marie Skłodowska-Curie (COFUND—Grant Agreement n 8 8 291780

    The role of weeds in the Integrated Pest Management of the white-spotted stinkbug of rice, "Eysarcoris ventralis"

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    “Eysarcoris ventralis” (Hemiptera, Pentatomidae) es la principal plaga del cultivo del arroz en la provincia de Sevilla. Se presenta su dinámica poblacional en la zona y los huéspedes alternativos. “Polypogon monspeliensis” es el huésped fundamental de febrero a julio. El cultivo del arroz sólo se ve atacado por la 5ª y última generación. Ante la ausencia de sustancias activas registradas para su control en Sevilla, se plantea el manejo de la vegetación espontánea huésped como la herramienta más eficaz para reducir las poblaciones y evitar daños al cultivo.“Eysarcoris ventralis” (Hemiptera, Pentatomidae) is the main rice pest in Seville province. Its seasonal development in the area and alternative hosts are presented. “Polypogon monspeliensis” is the main host from February to July. It is only the fifth and last generation that feeds on rice plants. Due to the absence of registered active substances for its control in Sevilla, it is proposed to manage weed host plants as the most effective tool to reduce populations and avoid damage

    Geomatic methods applied to the change study of the la Paúl Rock Glacier, Spanish Pyrenees

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    Producción CientíficaRock glaciers are one of the most important features of the mountain permafrost in the Pyrenees. La Paúl is an active rock glacier located in the north face of the Posets massif in the La Paúl glacier cirque (Spanish Pyrenees). This study presents the preliminary results of the La Paúl rock glacier monitoring works carried out through two geomatic technologies since 2013: Global Navigation Satellite System (GNSS) receivers and Terrestrial Laser Scanning (TLS) devices. Displacements measured on the rock glacier surface have demonstrated both the activity of the rock glacier and the utility of this equipment for the rock glaciers dynamic analysis. The glacier has exhibited the fastest displacements on its west side (over 35 cm yr-1), affected by the Little Ice Age, and frontal area (over 25 cm yr-1). As an indicator of permafrost in marginal environments and its peculiar morphology, La Paúl rock glacier encourages a more prolonged study and to the application of more geomatic techniques for its detailed analysis.Ministerio de Economía, Industria y Competitividad - Fondo Europeo de Desarrollo Regional (project CGL2015-68144-R)Junta de Extremadura - Fondo Europeo de Desarrollo Regional (project GR10071

    Efficiency and Innovation in Sub-Networks of Companies. A Study of the Spanish Ceramics District

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    La homogeneidad dentro del distrito industrial frente a las empresas externas se ha asumido tradicionalmente en la literatura. Sin embargo, nuestro trabajo sugiere que los distritos muestran un cierto grado de heterogeneidad. Así puede, atendiendo a variables relacionales, hablarse de la existencia de una core network y de una periphery network. A partir de un método cuantitativo se pretende investigar, para el caso del distrito industrial de la cerámica de Castellón (españa), la existencia de diferencias significativas en eficiencia técnica e innovación entre estos dos grupos de empresas. La confirmación de la heterogeneidad interna concita nuevas líneas de trabajo en el campo de los distritos industriales.Homogeneity in the industrial district with respect to outside companies has traditionally been an assumption in the literature. However, this paper suggests that districts show a certain degree of heterogeneity. Thus, based on relational variables, two different networks can be referred to: Core and Periphery. These groups of firms vary in terms of behavior and performance. Using quantitative methods, this research explores the existence of significant differences in technical efficiency and innovation between the two groups of firms in the spanish ceramic tile industrial district. Findings confirming internal heterogeneity suggest new lines of research in this field.L'homogénéité à l'intérieur du district industriel face aux entreprises externes a traditionnellement été assumée dans la littérature. Cependant, notre travail suggère que les districts montrent un certain degré d'hétérogénéité. Il est donc possible, tenant compte de variables relationnelles, de considérer l'existence de core network et de periphery network. À partir d'une méthode quantitative, on prétend faire une recherche, pour le cas du district industriel de céramique de Castellón (espagne), sur l'existence de différences significatives en efficacité technique et en innovation entre ces deux groupes d'entreprises. La confirmation de l'hétérogénéité interne incite à ouvrir de nouvelles lignes de travail dans le champ des districts industriels.A homogeneidade dentro do setor industrial ante as empresas externas vem sendo assumido tradicionalmente na literatura. Contudo, nosso trabalho sugere que os setores mostram um grau de heterogeneidade. Assim, atendendo a variáveis relacionais, pode-se falar da existência de uma core network e de uma periphery network. A partir de um método quantitativo, pretende-se pesquisar, para o caso do setor industrial da cerâmica de Castellón (espanha), a existência de diferenças significativas em eficiência técnica e inovação entre estes dois grupos de empresas. A confirmação da heterogeneidade interna concita novas linhas de trabalhos no campo dos setores industriais.Esta investigación ha sido financiada por el Ministerio de Educación y Ciencia, Plan Nacional de I+D+i (2007-2010), proyecto “El Distrito Industrial: el impacto del Capital Social sobre la Gestión de la Cadena de Suministro” (SEJ2007-62876/ECON

    Efficiency of the ceramic industrial district firms in Castellón: a comparative analysis through non-radial measures

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    La homogeneidad de las empresas pertenecientes al distrito industrial ha sido asumida tradicionalmente en la literatura sobre el tema. Sin embargo, diversos autores han señalado la posibilidad de identificar subredes de relaciones diferentes dentro del mismo. Así, atendiendo a variables relacionales, puede hablarse de la existencia de una core network y de una periphery network (Morrison y Rabellotti, 2005), con diferencias en su comportamiento y resultados. En este trabajo se pretende investigar, para el caso del distrito industrial de la cerámica de Castellón (España), la existencia de diferencias significativas en eficiencia entre estos dos grupos de empresas. Para ello se recurre a una metodología que permite estimar medidas no radiales de eficiencia, obteniéndose para cada una de las empresas un índice de eficiencia de cada uno de los inputs considerados al caracterizar el proceso de transformación, y a partir de estos una medida de eficiencia global. La confirmación de la heterogeneidad interna concita nuevas líneas de trabajo en el campo de los distritos industrialesScholars and practitioners have been led to rethink the principles of territorial systems, such as industrial district. Some authors have pointed the possibility to identified diverse networks of relations inside one district. For instance, and based on relational variables, can be found two different networks: Core and Periphery (Morrison and Rabellotti, 2005). These groups of firms vary in terms of behavior and performance. This research explores for the case of the Spanish ceramic tile industrial district the existence of significant differences in efficiency between the two groups of firms. Findings confirming internal heterogeneity suggest new lines of research in this fieldEsta investigación ha sido financiada por el Ministerio de Educación y Ciencia, Plan Nacional de I+D+i (2007-2010), proyecto “El Distrito Industrial: el impacto del Capital Social sobre la Gestión de la Cadena de Suministro” (SEJ2007-62876/ECON

    Imagen producto-país y crisis en el sector hortícola español: clasificación e impacto en el mercado

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    [EN] This research provides a conceptual framework to analyse the concept of ‘crisis’ and its multiple origins in the Spanish horticultural sector, the largest horticultural exporter in Europe. For this purpose, this study provides a typology of crises and a classification according to their nature, reasons, and temporary impact. Consequently, this research reviews and chronologically classifies the harmful campaigns that have originated several of those crises. Additionally, the impact on the perceived product-country image is analysed through an empirical research based on the results of a survey of consumers in several European countries.[ES] Esta investigación proporciona un marco conceptual para analizar el concepto “crisis” y sus orígenes en el sector hortícola español, el mayor exportador hortícola de Europa. Para este propósito, este estudio proporciona una tipología de crisis y una clasificación de acuerdo con su naturaleza, motivos e impacto temporal. En consecuencia, esta investigación revisa y clasifica cronológicamente las campañas inter-nacionales perjudiciales que han originado varias de esas crisis. Además, el impacto en la imagen percibida del producto-país se analiza a través de una investigación empírica basada en los resultados de una encuesta dirigida a consumidores finales en varios países europeos.Serrano-Arcos, MM.; Pérez-Mesa, JC.; Sánchez-Fernández, R. (2018). Product-country image and crises in the Spanish horticultural sector: Classification and impact on the market. Economía Agraria y Recursos Naturales - Agricultural and Resource Economics. 18(1):111-133. doi:10.7201/earn.2018.01.05SWORD11113318

    Generalized continuum model for the analysis of nonlinear vibrations of taut strings with microstructure

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    Classical continuum models are unable to capture the response of a microstructured solid when the scale effect is relevant. In vibration analysis, this limitation appears when the solid undergoes vibrations of wavelength that approaches the characteristic length of the microstructure. A discrete model may be formulated to account for this effect, but this comes at the expenses of high computational costs. For example, scale effects are relevant in strings employed in sensing applications which often rely on information gathered in the nonlinear dynamic regime. In this work, we study the dynamic behavior of a taut string modeled as a lattice of particles linked to first neighbors by linear springs. We develop an inertia-gradient generalized continuum model of the chain, which undergoes nonlinear vibrations. Unlike the corresponding classical continuum model, enrichment of the kinetic energy density with the characteristic length of the microstructure permits the model to capture short-wavelength vibrations. Comparison of the response predicted by the continuum models highlights that the generalized model provides better estimations of the dynamic response of the considered microstructured string in the nonlinear regime and at short wavelengths.Program during academic year 2017-18. This work was supported by the Ministerio de Economía y Competitividad de España (grant numbers DPI2014-57989-P and BES-2015-073720).Publicad

    Evaluación de preferencias híbridas para la investigación turística utilizando opiniones solicitadas y no solicitadas: una aplicación en turismo rural

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    Social media analysis is a powerful tool for tourism research that, at a relatively low cost, can be used to manage and process large datasets of comments, ratings, and shares from different online communities. However, the heterogeneous nature of unsolicited opinions, the complexity of natural language assessment, and differences in the characteristics of social-data sources hinder the accurate assessment of preferences. Likewise, the use of solicited data sources, such as direct polling, is typically resource-intensive, time-consuming, and geographically limited. We analyze a hybrid approach that combines active polling with passive social media analysis to rate tourist experience. To this end, we present a novel multiple criteria decision analysis model for preference-extraction from solicited and unsolicited data. The proposed approach can significantly reduce the number of polls required to accurately assess the preferences of a community, especially when surveying rural destinations, which are sparsely populated geographic areas situated outside cities and towns.info:eu-repo/semantics/publishedVersio

    OTELO survey: optimal emission-line flux determination with OSIRIS/GTC

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    Emission-line galaxies are important targets for understanding the chemical evolution of galaxies in the universe. Deep, narrow-band imaging surveys allow to detect and study the flux and the equivalent widths (EW) of the emission line studied. The present work has been developed within the context of the OTELO project, an emission line survey using the Tunable Filters (TF) of OSIRIS, the first generation instrument on the GTC 10.4m telescope located in La Palma, Spain, that will observe through selected atmospheric windows relatively free of sky emission lines. With a total survey area of 0.1 square degrees distributed in different fields, reaching a 5 \sigma depth of 10^-18 erg/cm^2/s and detecting objects of EW < 0.3 A, OTELO will be the deepest emission line survey to date. As part of the OTELO preparatory activities, the objective of this study is to determine the best combination of sampling and full width at half maximum (FWHM) for the OSIRIS tunable filters for deblending H\alpha from [NII] lines by analyzing the flux errors obtained. We simulated the OTELO data by convolving a complete set of synthetic HII galaxies in EW with different widths of the OSIRIS TFs. We estimated relative flux errors of the recovered H\alpha and [NII]6583 lines. We found that, for the red TF, a FWHM of 12 A and a sampling of 5 A is an optimal combination that allow deblending H\alpha from the [NII]6583 line with a flux error lower than 20%. This combination will allow estimating SFRs and metallicities using the H\alpha flux and the N2 method, respectively.Comment: 16 pages, 9 figures. Some authors added. Accepted for publication in PAS
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