7,145 research outputs found

    Band gap engineering of MoS2_2 upon compression

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    Molybdenum disulfide (MoS2_2) is a promising candidate for 2D nanoelectronic devices, that shows a direct band-gap for monolayer structure. In this work we study the electronic structure of MoS2_2 upon both compressive and tensile strains with first-principles density-functional calculations for different number of layers. The results show that the band-gap can be engineered for experimentally attainable strains (i.e. ±0.15\pm 0.15). However compressive strain can result in bucking that can prevent the use of large compressive strain. We then studied the stability of the compression, calculating the critical strain that results in the on-set of buckling for free-standing nanoribbons of different lengths. The results demonstrate that short structures, or few-layer MoS2_2, show semi-conductor to metal transition upon compressive strain without bucking

    Measuring Regional Cohesion Effects of Large-scale Transport Infrastructure Investments: An Accessibility Approach.

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    Cohesion is considered one of the main policy goals both at a EU an national level. However, there is currently a lack of a common approach to measure cohesion effects of large-scale transport infrastructure investments. Accessibility indicators have an unexploited potential in transportation assessment methodologies. Accessibility is considered an added value of locations, which represents one of the elements contributing to a region’s welfare. Therefore, spatial distribution of accessibility may be used as a proxy to assess regional cohesion. This paper suggests an approach consisting in measuring changes in the spatial distribution of four different accessibility indicators, computed and mapped using a GIS support. Cohesion is subsequently measured calculating a set of inequality indices of the resulting accessibility distribution. It is possible then to assess whether disparities in regional accessibility are increased or reduced after the implementation of a new transport infrastructure. This approach is tested assessing regional cohesion effects of road and rail network developments in Spain in the period 1992-2004. Comparing the results obtained with accessibility indicators and inequality indices allows identifying the main critical factors and sources of bias. The conclusion is that for the rode mode, cohesion has improved, while regional disparities have increased for the rail mode

    Fragmentos de una reflexión sobre literatura y fotografía

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    La interrelación literatura/fotografía supone un campo de investigación muy amplio y complejo, por lo que este trabajo consiste en un trazado general señalando los momentos más significativos de la historia de dicha interrelación en nuestra cultura europea más inmediata. Se parte de la perspectiva de la literatura y de la fotografía como medios de comunicación. Su diferente naturaleza pone de manifiesto una confluencia básica: el arte y la industria. Se considera como antecedente y referente inmediato la relación literatura/pintura para analizar el impacto causado por la aparición de la fotografía. Se perfila un itinerario que va desde la desconfianza inicial de los escritores (al no ser este nuevo medio un producto artístico), hasta su plena aceptación y enriquecimientos recíprocos entre ambos medios. En este camino se deducen dos líneas de interacción literatura/fotografía hasta desembocar en un producto híbrido con autonomía propia: la fotonovela. Se concluye con la reflexión sobre un nuevo destino para ambos medios en el campo común del mundo digital.The interrelation between literature and photography is a wide and complex field of study. This is a general overview in which the main aspects of this interrelation are highlighted. The history of literature and photography as mass media is taken as a point of departure and their overlapping aspects are studied in order to see the connexion between arts and industry. This relationship is seen as both an antecedent as well as an immediate reference for this appearance of photography. A path can be traced from the first writers suspiciouness (due to the fact that photography was not considered an artistic product), until the whole acceptance and following success of both means. Two lines can be observed between this interaction of literature and photography to finally give origin to a new independent genre: the «photonovel». It ends with the reflection about a new kind of interaction between both media in the common ground for digital world

    Aproximación al paratexto de las ediciones del siglo XVI de las Obras de Boscán y algunas de Garcilaso de la Vega

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    De acuerdo con la codificación del paratexto de G.Genette, se analizan los elementos paratextuales de las ediciones de esta obra (prólogos, dedicatorias e índices) publicadas en las distintas tipografías europeas durante el siglo xvi. Se han cotejado fundamentalmente ejemplares depositados en la Biblioteca Nacional de España. Dicho análisis desvela aspectos relativos al contexto cultural y editorial y se infiere que tales ediciones, con escaso cuidado en la tipografía, formaron parte de un circuito de producción editorial de «consumo» en el que es capital la intermediación del editor/impresor y la competitividad en el mercado de la edición de la época.This essay analyzes, according to G. Genette's definition of paratext, the paratextual elements (prologues, dedications, indexes) of the different editions of the Boscan's work published in 16th century European printing houses. Through the comparison of copies in the Biblioteca Nacional de España, this analysis reveals several aspects of the cultural and editorial context and concludes that these editions, that present a poor typography, were devoted to an editorial consuming market where the mediation of the editor / printer and the competitiveness in the editorial marked of the century were capital

    A critical appraisal of phloem-mobile signals involved in tuber induction

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    The identification of FLOWERING LOCUS T (FT) and several FT homologs as phloem-mobile proteins that regulate flowering has sparked the search for additional homologs involved in the long-distance regulation of other developmental processes. Given that flowering and tuber induction share regulatory pathways, the quest for long-distance tuberization signals has been further stimulated. Several tuberization regulators have been proposed as mobile molecules, including the FT family protein StSP6A, the plant growth regulators gibberellins and the microRNA miR172. Although some of these hypotheses are attractive and plausible, evidence that these molecules are transmissible in potato has yet to be obtained. Two mRNAs encoding transcription factors, StBEL5 and POTATO HOMEOBOX 1 (POTH1), are mobile and correlate with tuber induction. However, evidence that StBEL5 or POTH1 are required for tuberization is not available yet. Therefore, there are several good candidates for long-distance molecules in the tuberization process. Further research should test their role as systemic tuberization signals

    Effect of Absorption and Desorption of Hydrogen in Ti and Ti Alloys

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    A study of the hydrogen (H) storage capacity of pure Ti and the Ti‐6Al‐4V alloy is presented. The importance of an accurate quantification of oxygen and hydrogen in the materials used for hydrogen storage, the activation process and the cyclic hydrogenations, the effect of surface quality during hydrogen uptake, the improvement of hydrogen absorption using ion irradiation, and the hydrogen desorption are some topics discussed in this chapter
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