8,160 research outputs found

    Tilt Induced Localization and Delocalization in the Second Landau Level

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    We have investigated the behavior of electronic phases of the second Landau level under tilted magnetic fields. The fractional quantum Hall liquids at ν=\nu=2+1/5 and 2+4/5 and the solid phases at ν=\nu=2.30, 2.44, 2.57, and 2.70 are quickly destroyed with tilt. This behavior can be interpreted as a tilt driven localization of the 2+1/5 and 2+4/5 fractional quantum Hall liquids and a delocalization through melting of solid phases in the top Landau level, respectively. The evolution towards the classical Hall gas of the solid phases is suggestive of antiferromagnetic ordering

    Coleta de dados em campo com auxílio de dispositivos móveis Android.

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    Este Comunicado Técnico visa apresentar os passos necessários para a utilização do programa GeoPaparazzi no campo, incluindo a instalação e o funcionamento do programa, a geração de mapas base personalizados, a configuração de formulários de coleta de dados e a exportação dos dados coletados. Pressupõe-se que o leitor tenha domínio de algumas operações, como procedimentos para copiar dados do computador pessoal para o dispositivo móvel e vice-versa, gerar mapas base ou mosaicos georreferenciados e utilizar programas via linha de comando no computador pessoal.bitstream/item/99818/1/CT-34.pd

    Tailored graph ensembles as proxies or null models for real networks I: tools for quantifying structure

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    We study the tailoring of structured random graph ensembles to real networks, with the objective of generating precise and practical mathematical tools for quantifying and comparing network topologies macroscopically, beyond the level of degree statistics. Our family of ensembles can produce graphs with any prescribed degree distribution and any degree-degree correlation function, its control parameters can be calculated fully analytically, and as a result we can calculate (asymptotically) formulae for entropies and complexities, and for information-theoretic distances between networks, expressed directly and explicitly in terms of their measured degree distribution and degree correlations.Comment: 25 pages, 3 figure

    Non-thermal origin of nonlinear transport across magnetically induced superconductor-metal-insulator transition

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    We have studied the effect of perpendicular magnetic fields and temperatures on the nonlinear electronic transport in amorphous Ta superconducting thin films. The films exhibit a magnetic field induced metallic behavior intervening the superconductor-insulator transition in the zero temperature limit. We show that the nonlinear transport in the superconducting and metallic phase is of non-thermal origin and accompanies an extraordinarily long voltage response time.Comment: 5 pages, 4 figure

    Identification of mineral components in tropical soils using reflectance spectroscopy and advanced spaceborne thermal emission and reflection radiometer (ASTER) data.

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    Soil characteristics provide important support for understanding transformations that occur in environmental systems. Physical characteristics and chemical compositions of soils controlled by pedogenetic processes, climatic changes and land use imply different types of environmental transformations. Reflectance spectroscopy is an alternative soil mapping technique that uses spectral absorption features between visible (VIS) and short-wave infrared (SWIR) wavelengths (0.3?2.5 μm) for determining soil mineralogy. Soil analysis by means of reflectance spectroscopy and orbital optical sensors have provided favorable results in mapping transformation processes in environmental systems, particularly in arid and semiarid climates in extra-tropical terrains. In the case of inter-tropical environments, these methods cannot be readily applied due to local factors such as lack of exposed regolith, high amounts of soil moisture and the presence of dense vegetation. This study uses Advanced Spaceborne Thermal Emission and Reflection Radiometer (ASTER) and reflectance spectroscopy data to map mineral components of soils covering a part of the state of São Paulo, Brazil, which could be linked to key aspects of environmental transformations in this tropical area (e.g., climate change, shifts in agriculture fronts, ph, and soil characteristics). We collected forty-two (42) soil samples at a depth of 0?20 cm, considering that this superficial layer corresponds to the highest correlation with soil properties detected by the ASTER sensor. These samples were measured using a FieldSpec FR spectrometer, and the derived spectra were interpreted for mineral composition. Interpretation was supported by X-ray diffraction analysis on the same samples. The spectral signatures were re-sampled to ASTER VNIR (AST1-4: 0.52?0.86 μm) and SWIR (AST5-9: 1.60?2.43 μm) spectral bandwidths and validated by comparing reflectance spectra of field samples with those extracted from atmospherically corrected and calibrated ASTER pixels. The agreement between spectral signatures measured from soil samples and those derived from ASTER imagery pixels proved plausible, with R2 correlation values ranging from 0.6493 to 0.7886. This signifies that diagnostic spectral features of key minerals in tropical soils can be mapped at the spectral resolution of 9-band ASTER VNIR through SWIR reflectance. We used these spectral signatures as end-members in hyperspectral routine classifications adapted for use with ASTER data. Results proved possible the identification and remote mapping of minerals such as kaolinite, montmorillonite and gibbsite, as well as the distinction between iron-rich and iron-poor soils

    Mapeamento e identificação da época de desmatamento das áreas de expansão da agricultura no MATOPIBA.

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    Esse trabalho teve como objetivo avaliar a expansão da agricultura do bioma Cerrado na região do MATOPIBA, através de máscaras agrícolas geradas a partir das séries temporais de índice de vegetação NDVI do sensor MODIS, e identificar a época em que ocorreu o desmatamento das áreas de expansão, utilizando os mapas de área antropizada do Projeto de Monitoramento do Desmatamento dos Biomas Brasileiros por Satélite (PMDBBS)

    Mapeamento semiautomático de áreas agrícolas no Estado do Mato Grosso.

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    A soja é a cultura agrícola que mais cresceu nas últimas décadas no Brasil. O crescimento da produtividade está associado aos avanços tecnológicos, ao manejo e à eficiência dos produtores. O cultivo ocorre principalmente nas regiões Centro-Oeste e Sul do país, onde a soja firmou-se como um dos produtos mais destacados da agricultura nacional e da balança comercial. Entre as tecnologias disponíveis para o monitoramento de atividades agrícolas podemos citar as imagens orbitais do sensor Moderate Resolution Imaging Spectroradiometer (MODIS). Este trabalho tem como objetivo identificar e mapear as grandes áreas agrícolas do Estado de Mato Grosso por meio de imagens do sensor MODIS dos anos de 2009, 2010, 2011 e 2012. Os resultados obtidos foram comparados a estimativas de área plantada do IBGE e mostram boa concordância entre os dados estimados por sensoriamento remoto e estimativas oficiais

    Cost - minimization Analysis of Treprostinil vs. Epoprostenol as an Alternate to Oral Therapy: Non - responders for the Treatment of Pulmonary Arterial Hypertension

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    Idiopathic pulmonary arterial hypertension (IPAH) is associated with substantial morbidity and mortality. Treprostinil was compared to epoprostenol for the economic impact of treating IPAH patients who failed or were not candidates for bosentan. METHODS: The model was a cost-minimization analysis, assuming clinical equivalence was achieved by proper dosing of both drugs, in terms of survival and surrogate measures. Two theoretical cohorts of 270 patients were treated with subcutaneous treprostinil and intravenous epoprostenol, and were evaluated over 3 years using a spreadsheet model. Annual survival rates were estimated for the cohorts so that at endpoint 114 (42%) patients survived in both groups. The model utilized resource valuation data for medication and supply costs from Medicare; hospital, consultation, surgical, and diagnostic procedural fees from North Carolina hospitals; and costs to treat adverse events from published sources. Costs were obtained from standard lists and were presented as 2003 US dollars, discounted at 3%. Sensitivity analyses were performed testing all model uncertainties. RESULTS: In the base case analysis, treprostinil demonstrated savings of 22,701 US dollars and 37,433 US dollars per patient over 1- and 3-year time horizons, respectively. The greatest savings came from reduced or minimal hospitalizations attributed to the dose titration and treatment of adverse events, such as sepsis, associated with epoprostenol and its delivery system. Probabilistic sensitivity analyses resulted in average 3-year cost-savings of 41,051 US dollars (Standard Deviation = 13,902 US dollars) per patient. CONCLUSIONS: By initiating and continuing treatment with treprostinil over a 3-year period, the economic burden associated with IPAH may be reduced compared to treatment with epoprostenol. The greatest saving with treprostinil was attributed to decreased sepsis
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