2,586 research outputs found

    Adsorption of Sugars on Al- and Ga-doped Boron Nitride Surfaces: A Computational Study

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    Molecular adsorption on surfaces is a key element for many applications, including sensing and catalysis. Non-invasive sugar sensing has been an active area of research due to its importance to diabetes care. The adsorption of sugars on a template surface study is at the heart of matter. Here, we study doped hexagonal boron nitride sheets (hh-BNNs) as adsorbing and sensing template for glucose and glucosamine. Using first principles calculations, we find that the adsorption of glucose and glucosamine on hh-BNNs is significantly enhanced by the substitutional doping of the sheet with Al and Ga. Including long range van der Waals corrections gives adsorption energies of about 2 eV. In addition to the charge transfer occurring between glucose and the Al/Ga-doped BN sheets, the adsorption alters the size of the band gap, allowing for optical detection of adsorption. We also find that Al-doped boron nitride sheet is better than Ga-nitride sheet to enhance the adsorption energy of glucose and glucosamine. The results of our work can be potentially utilized when designing support templates for glucose and glucosamine

    Propuesta de un modelo gerencial aplicado a proyectos de Infraestructura vial adjudicados por el Instituto de Desarrollo Urbano (IDU), a partir de la metodología PMBOK

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    Trabajo de investigaciónBasados en la experiencia en la ejecución de contratos de mantenimiento de la infraestructura Vial del Instituto de Desarrollo Urbano (IDU) en la ciudad de Bogotá y en las constantes problemáticas que surgen en las etapas constructivas de los proyectos de mantenimiento. Es necesario buscar alternativas desde el punto de vista de dirección de proyectos para mitigar las circunstancias que no permiten cumplir las expectativas tanto técnicas como económicas de estos proyectos. Enfocados en una correcta planeación, ejecución y control, con el fin de suplir cada una de las necesidades del IDU y de las diferentes tipologías de contratos de mantenimiento ofrecidas por dicha entidad, es por eso que surge la necesidad de generar una herramienta que basada en la experiencia en situaciones atípicas presentadas en la ejecución de proyectos de mantenimiento y en la metodología PMBOK logre mostrar un norte para enfrentarse de una manera coherente a la gerencia de obra en uno de estos contratos.Introducción 1 Generalidades 2 Marcos de referencia 3 Metodología 4 Productos a entregar 5 Descripción de resultados esperados e impacto 6 Desarrollo del proyecto 7 Conclusiones 8 Bibliografía 9 AnexosEspecializaciónEspecialista en Gerencia de Obras Civile

    Crown Graphene Nanomeshes: Highly Stable Chelation-Doped Semiconducting Materials

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    Graphene nanomeshes (GNM's) formed by the creation of pore superlattices in graphene, are a possible route to graphene-based electronics due to their semiconducting properties, including the emergence of fractional eV band gaps. The utility of GNM's would be markedly increased if a scheme to stably and controllably dope them was developed. In this work, a chemically-motivated approach to GNM doping based on selective pore-perimeter passivation and subsequent ion chelation is proposed. It is shown by first-principles calculations that ion chelation leads to stable doping of the passivated GNM's -- both {\it n}- and {\it p}-doping are achieved within a rigid-band picture. Such chelated or ``crown'' GNM structures are stable, high mobility semiconducting materials possessing intrinsic doping-concentration control; these can serve as building blocks for edge-free graphene nanoelectronics including GNM-based complementary metal oxide semiconductor (CMOS)-type logic switches.Comment: 18 pages, 6 figure

    A French Fairy Tale Corpus syntactically and semantically annotated.

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    International audienceFairy tales, folktales and more generally children stories have lately attracted the Natural Language Processing (NLP) community. As such, very few corpora exist and linguistic resources are lacking. The work presented in this paper aims at filling this gap by presenting a syntactically and semantically annotated corpus. It focuses on the linguistic analysis of a Fairy Tales Corpus, and provides the description of the syntactic and semantic resources developed for Information Extraction. Resources include syntactic dependency relation annotation for 120 verbs; referential annotation, which is concerned with annotating each anaphoric occurrence and Proper Name with the most specific noun in the text; ontology matching for a substantial part of the nouns in the corpus; semantic role labelling for 41 verbs using the FrameNet database. The article also sums up previous analyses of this corpus and indicates possible uses of this corpus for the NLP community

    CAL Dataflow Components for an MPEG RVC AVC Baseline Encoder

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    In this paper, an efficient H.264/AVC baseline encoder, described in RVC-CAL actor language, is introduced. The main aim of the paper is twofold: a) to demonstrate the flexibility and ease that is provided by RVC-CAL, which allows for efficient implementation of the presented encoder, and b) to shed light on the advantages that can be brought into the RVC framework by including such encoding tools. The main modules of the designed encoder include: Inter Frame Prediction (Motion Estimation/Compensation), Intra Frame Prediction, and Entropy Coding. Descriptions of the designed modules, accompanied with RVC-CAL design issues are provided. A comparison between different development approaches is also provided. The obtained results show that specifying complex video codecs (e.g. H.264/AVC encoder) using RVC-CAL followed by automatic translation into HDL, which is achievable by the tools that support the standard, results in more efficient HW implementation compared to the traditional HW design flow. A discussion that explains the reasons behind such results concludes the pape
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