9 resultados para fragmentation


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"Click" chemistry has become an efficient avenue to unimolecular polymeric nanoparticles through the self-crosslinking of individual polymer chains containing appropriate functional groups. Herein we report the synthesis of ultra-small (7 nm in size) polymethyl methacrylate (PMMA) nanoparticles (NPs) by the "metal-free" cross-linking of PMMA-precursor chains prepared by reversible addition-fragmentation chain transfer (RAFT) polymerization containing beta-ketoester functional groups. Intramolecular collapse was performed by the one-pot reaction of beta-ketoester moieties with alkyl diamines in tetrahydrofurane at r.t. (i.e., by enamine formation). The collapsing process was followed by size exclusion chromatography and by nuclear magnetic resonance spectroscopy. The size of the resulting PMMA-NPs was determined by dynamic light scattering. Enamine "click" chemistry increases the synthetic toolbox for the efficient synthesis of metal-free, ultra-small polymeric NPs.

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670 p. Capítulos de introducción, metodología, discusión y conclusiones en castellano e inglés.

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Coherent ecological networks (EN) composed of core areas linked by ecological corridors are being developed worldwide with the goal of promoting landscape connectivity and biodiversity conservation. However, empirical assessment of the performance of EN designs is critical to evaluate the utility of these networks to mitigate effects of habitat loss and fragmentation. Landscape genetics provides a particularly valuable framework to address the question of functional connectivity by providing a direct means to investigate the effects of landscape structure on gene flow. The goals of this study are (1) to evaluate the landscape features that drive gene flow of an EN target species (European pine marten), and (2) evaluate the optimality of a regional EN design in providing connectivity for this species within the Basque Country (North Spain). Using partial Mantel tests in a reciprocal causal modeling framework we competed 59 alternative models, including isolation by distance and the regional EN. Our analysis indicated that the regional EN was among the most supported resistance models for the pine marten, but was not the best supported model. Gene flow of pine marten in northern Spain is facilitated by natural vegetation, and is resisted by anthropogenic landcover types and roads. Our results suggest that the regional EN design being implemented in the Basque Country will effectively facilitate gene flow of forest dwelling species at regional scale.

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For efficient use of conservation resources it is important to determine how species diversity changes across spatial scales. In many poorly known species groups little is known about at which spatial scales the conservation efforts should be focused. Here we examined how the community turnover of wood-inhabiting fungi is realised at three hierarchical levels, and how much of community variation is explained by variation in resource composition and spatial proximity. The hierarchical study design consisted of management type (fixed factor), forest site (random factor, nested within management type) and study plots (randomly placed plots within each study site). To examine how species richness varied across the three hierarchical scales, randomized species accumulation curves and additive partitioning of species richness were applied. To analyse variation in wood-inhabiting species and dead wood composition at each scale, linear and Permanova modelling approaches were used. Wood-inhabiting fungal communities were dominated by rare and infrequent species. The similarity of fungal communities was higher within sites and within management categories than among sites or between the two management categories, and it decreased with increasing distance among the sampling plots and with decreasing similarity of dead wood resources. However, only a small part of community variation could be explained by these factors. The species present in managed forests were in a large extent a subset of those species present in natural forests. Our results suggest that in particular the protection of rare species requires a large total area. As managed forests have only little additional value complementing the diversity of natural forests, the conservation of natural forests is the key to ecologically effective conservation. As the dissimilarity of fungal communities increases with distance, the conserved natural forest sites should be broadly distributed in space, yet the individual conserved areas should be large enough to ensure local persistence.

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[ES]El presente TFG plantea un análisis de la utilización de las redes sociales dentro de la estrategia de comunicación de las organizaciones empresariales. Para ello, se estudia el contexto comunicacional actual, caracterizado por la fragmentación y dispersión de las audiencias, la saturación, la pérdida de la eficacia de la publicidad tradicional, los nuevos hábitos de consumo de medios y la explosión de la conectividad, y el papel de las distintas herramientas de comunicación en entornos digitales: página web, blog corporativo, email marketing, gestión multimedia, mobile marketing, E-commerce y Social Media Marketing. En este contexto y por su relevancia, nos centramos en el estudio de las estrategias de Social Media Marketing. Para ello abordamos las ventajas e inconvenientes de la utilización de redes sociales, cómo efectuar la planificación de la comunicación en redes sociales (objetivos, público, contenidos, plataformas, plan de acción e indicadores), y las nuevas profesiones ligadas a su gestión. Un aspecto relevante que también se analiza es la gestión de la reputación online y las implicaciones que el uso de redes sociales tiene sobre ella, así como los protocolos de actuación ante posibles crisis derivadas de la presencia en estos canales. En las redes sociales se encuentran prácticamente todos los stakeholders de las empresas/marcas, fuente de información continua para mejorar sus negocios. Su utilización, dentro de una comunicación integral de marketing, permite fortalecer la imagen corporativa y lograr un posicionamiento claro y a largo plazo.

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[ES] Los conjuntos de glosas conservados en los mss. medievales representan a menudo la culminación de sucesivos y complicados procesos de fragmentación, reagrupación o/y reelaboración. Debido a su inestabilidad, estos conjuntos constituyen composiciones únicas, por lo que a la hora de editarlos la mejor opción consiste en partir del material conservado en un solo ms., sin utilizar varios testimonios para tratar de reconstruir un texto cuya existencia es meramente conjetural. Este proceder no excluye la posibilidad de recurrir al contenido de otros mss. que transmiten glosas similares a aquellas que forman el conjunto que uno trata de editar y, de hecho, en los casos en los que el contenido de este último resulta problemático o manifiestamente defectuoso, el recurso a estos testimonios paralelos es, más que una posibilidad, una exigencia. El análisis de las dos ediciones del "Commentum Monacense" a Terencio confeccionadas hasta la fecha —la de F. Schlee y la de F. Schorsch— nos proporciona algunos ejemplos concretos al respecto.

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4th International Workshop on Transverse Polisarization Phenomena in Hard Processes (TRANSVERSITY 2014)

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4th International Workshop on Transverse Polisarization Phenomena in Hard Processes (TRANSVERSITY 2014)