Suppression of Anderson localization of light and Brewster anomalies in disordered superlattices containing a dispersive metamaterial

Light propagation through 1D disordered structures composed of alternating layers, with random thicknesses, of air and a dispersive metamaterial is theoretically investigated. Both normal and oblique incidences are considered. By means of numerical simulations and an analytical theory, we have established that Anderson localization of light may be suppressed: (i) in the long wavelength limit, for a finite angle of incidence which depends on the parameters of the dispersive metamaterial; (ii) for isolated frequencies and for specific angles of incidence, corresponding to Brewster anomalies in both positive- and negative-refraction regimes of the dispersive metamaterial. These results suggest that Anderson localization of light could be explored to control and tune light propagation in disordered metamaterials.Comment: 4 two-column pages, 3 figure

Vegetation composition and forage mass in grassland with a double structure under two winter grazing regimes.

Remnant areas of Pampas grassland have a distinct double structure. Efficiency of livestock farming on these grasslands depends on practices that are synchronized with natural variation. This study examined the changes in vegetation composition and forage mass during winter to understand the effects of grazing methods in a natural pasture with a double structure that was grazed by heifers

Caracterização do solo sob campo nativo em Bagé/RS, Lavras do Sul/RS e Vacaria/RS .

Os solos agrícolas possuem o maior estoque terrestre de carbono orgânico, sendo um quarto em áreas com pastagens naturais cujas características são dependentes do manejo adotado

Quantitative magneto-optical investigation of superconductor/ferromagnet hybrid structures

We present a detailed quantitative magneto-optical imaging study of several superconductor/ferromagnet hybrid structures, including Nb deposited on top of thermomagnetically patterned NdFeB, and permalloy/niobium with erasable and tailored magnetic landscapes imprinted in the permalloy layer. The magneto-optical imaging data is complemented with and compared to scanning Hall probe microscopy measurements. Comprehensive protocols have been developed for calibrating, testing, and converting Faraday rotation data to magnetic field maps. Applied to the acquired data, they reveal the comparatively weaker magnetic response of the superconductor from the background of larger fields and field gradients generated by the magnetic layer.Comment: 21 pages, including 2 pages of supplementary materia

A Marketplace-based Approach to Cloud Network Slice Composition Across Multiple Domains

Cloud network slicing can be defined as the process that enables isolated end-to-end and on-demand networking abstractions, which: (a) contain both cloud and network resources, and (b) are independently controlled, managed and orchestrated. This paper contributes to the vision of the NECOS project and relevant platform, that aim to address the limitations of current cloud computing infrastructures to accomplish the challenging requirements of the slicing approach. The NECOS platform implements the Slice-as-a-Service model, enabling the dynamic creation of end-to-end (E2E) slices from a set of constituent slice parts contributed from multiple domains. A challenging issue is to define the facility that implements dynamic slice resource discovery, aligned to the requirements of the slice owner or tenant, over different infrastructure providers. Here, we propose a Marketplace-based approach implementing relevant federated interactions for the resource discovery and we detail its architecture, workflows, and information model. We also present its initial implementation details and provide both quantitative and qualitative experimental results validating its main operation

Efeito de duas intensidades de colheita de madeira na estrutura de uma floresta natural na região de Paragominas, Pará.

Foram estudadas as mudanças na estrutura de 108ha de uma floresta primária submetida a duas intensidades de colheita de madeira, na Fazenda Rio Capim, pertencente à Cikel Brasil Verde Madeiras Ltda., no município de Paragominas, Pará. Os dados foram coletados, em dois períodos (2003, antes da exploração, e 2004, após a exploração) em 36 parcelas permanentes quadradas de 0,25ha, estabelecidas aleatoriamente na área, sendo12 em floresta não-explorada: Testemunha - T0; 12 em floresta explorada com colheita apenas do fuste comercial das árvores: Tratamento - T1; e 12 em floresta explorada com colheita do fuste e dos resíduos lenhosos: Tratamento - T2. Em 2003 foram registrados 4469 indivíduos com DAP > 10cm, nas 36 parcelas amostradas (9ha). Sete meses após a exploração (2004), foram observados na área 4531 indivíduos com DAP > 10cm, sendo 4330 vivos. Lecythis idatimon, Poecilanthe effusa, Rinorea flavescens, Eschweilera grandiflora, Eschweilera pedicellata, Inga sp., Protium spp., Vouacapoua americana, Guatteria poeppigiana e Eschweilera coriacea foram as dez espécies mais importantes, tanto antes como após a exploração. A estrutura da floresta, tanto no T1 como no T2, sofreu alterações significantes devido à exploração a que foi submetida. Entretanto, não foram verificadas diferenças significativas entre os três tratamentos, sugerindo que com a intensidade de exploração aplicada, mais a retirada adicional dos resíduos, a floresta manteve as características semelhantes à floresta original, apesar do menor estoque de árvores adultas de espécies comerciais. Recomendam-se estudos sobre a regeneração natural (DAP < 10cm), silvicultura pós-colheita e crescimento da floresta