999 resultados para 15482-1


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Researchers want to run scientific experiments focusing on their disciplines. They do not want to know how and where the experiments are executed. Science gateways hide details by coordinating the execution of experiments using different infrastructures and workflow systems. ER-flow/SHIWA and SCI-BUS project developed repositories to share artefacts such as applications, portlets, workflows, etc. inside and among research communities. Sharing artefacts in re-positories enable gateway developers to reuse them when building a new gateway and/or creating a new application.

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The high dependence of herbivorous insects on their host plants implies that plant invaders can affect these insects directly, by not providing a suitable habitat, or indirectly, by altering host plant availability. In this study, we sampled Asteraceae flower heads in cerrado remnants with varying levels of exotic grass invasion to evaluate whether invasive grasses have a direct effect on herbivore richness independent of the current disturbance level and host plant richness. By classifying herbivores according to the degree of host plant specialization, we also investigated whether invasive grasses reduce the uniqueness of the herbivorous assemblages. Herbivorous insect richness showed a unimodal relationship with invasive grass cover that was significantly explained only by way of the variation in host plant richness. The same result was found for polyphagous and oligophagous insects, but monophages showed a significant negative response to the intensity of the grass invasion that was independent of host plant richness. Our findings lend support to the hypothesis that the aggregate effect of invasive plants on herbivores tends to mirror the effects of invasive plants on host plants. In addition, exotic plants affect specialist insects differently from generalist insects; thus exotic plants affect not only the size but also the structural profile of herbivorous insect assemblages.

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Anthropogenic disturbances frequently modify natural disturbance regimes and foster the invasion and spread of nonindigenous species. However, there is some dispute about whether disturbance events or invasive plants themselves are the major factors promoting the local extinction of native plant species. Here, we used a set of savanna remnants comprising a gradient of invasive grass cover to evaluate whether the species richness of Asteraceae, a major component of the Brazilian Cerrado, is affected by invasive grass cover, or alternatively, whether variation in richness can be directly ascribed to disturbance-related variables. Furthermore, we evaluate whether habitat-specialist Asteraceae differ from habitat generalist species in their responses to grass invasion. Abundance and species richness showed unimodal variation along the invasive grass gradient for both total Asteraceae and habitat-generalists. The cerrado-specialist species, however, showed no clear variation from low-to-intermediate levels of grass cover, but declined monotonically from intermediate-to-higher levels. Through a structural equation model, we found that only invasive grass cover had significant effects on both abundance and species density of Asteraceae. The effect of invasive grass cover was especially high on the cerrado-specialist species, whose proportion declined consistently with increasing invasive dominance. Our results support the prediction that invasive grasses reduce the floristic uniqueness of pristine vegetation physiognomies.

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Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

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La ciudad de Madrid ha sido y es uno de los principales polos de actividad científico-tecnológica de España. Concentra una parte fundamental de las instituciones públicas de investigación y desarrollo. Madrid ha sido un lugar de producción y localización científico-tecnológica de primer nivel nacional, desde los comienzos de la Ilustración en la época de Carlos III, posteriormente en el siglos XIX, en la época del "Cajalismo" de principios del XX, con la JAE (Junta de Ampliación de Estudios), con el CSIC y con el Ministerio de Ciencia e Innovación y Madrid Network. Ha existido una secuencia espacial y temporal en la localización de sedes de instituciones científico-técnicas en la ciudad a lo largo del tiempo. Con este trabajo de investigación se analiza la formación de este sistema y sus características básicas, se evalúa si ha formado un conjunto de áreas significativas en la ciudad que permitan hablar de un proyecto o conjunto de proyectos que han formado el sistema científico-técnico de Madrid. Finalmente se analiza cómo es en la actualidad este sistema y si está concluido o si por el contrario está pendiente de terminar y desarrollar en estos momentos a principios del siglo XXI.