6,903 research outputs found

    On the number of nonequivalent propelinear extended perfect codes

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    The paper proves that there exist an exponential number of nonequivalent propelinear extended perfect binary codes of length growing to infinity. Specifically, it is proved that all transitive extended perfect binary codes found by Potapov are propelinear. All such codes have small rank, which is one more than the rank of the extended Hamming code of the same length. We investigate the properties of these codes and show that any of them has a normalized propelinear representation

    HYPERTHYROIDISM AND PREGNANCY

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    Os autores descrevem as etiologias mais frequentes do hipertiroidismo que ocorre na gravidez e referem as alterações imunológicas que caracterizam a doença de Graves e a tolerância imunológica associada à gravidez. Referem o quadro clínico, o diagnóstico laboratorial e o tratamento a efectuar. Como o tratamento médico é o mais frequente, referem os antitiroideus de síntese, suas características e a opção mais conveniente para o tratamento durante a gravidez. The authors describe most common hyperthyroidism aetiologies that occur during pregnancy and also the immunity changes that define Graves disease and the immunity tolerance associated to pregnancy. They also refer the clinical pictur, laboratorial diagnosis and the treatment to be carried out. Medical treatment is mostly based on anti-thyroid drugs. Their characteristics and use during pregnancy are discussed

    Field sources in a Lorentz symmetry breaking scenario with a single background vector

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    This paper is devoted to investigating the interactions between stationary sources of the electromagnetic field, in a model which exhibits explicit Lorentz-symmetry breaking due to the presence of a single background vector. We focus on physical phenomena that emerge from this kind of breaking and which have no counterpart in Maxwell Electrodynamics

    Cutaneous side effects of diabetes treatment

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    As lesões cutâneas são frequentes na diabetes mellitus, havendo um envolvimento da pele em cerca de 30 a 91% dos doentes durante o curso da doença. Estas podem ser não infeciosas ou autoimunes, infeciosas ou resultar de complicações do tratamento da diabetes, pelo uso de insulina ou outros antidiabéticos. O crescente aumento na prevalência da diabetes mellitus tipo 2 e o advento, na última década, de novos antidiabéticos orais e injetáveis com diferentes mecanismos celulares de atuação, justificam não só uma adequada orientação técnica sobre a sequência de introdução de cada classe terapêutica, como o reconhecimento dos seus efeitos laterais, nomeadamente even- tuais reações cutâneas adversas. A resolução destas dermatoses passa pela substituição farmacológica ou pelo aumento da rotatividade do local onde se administra a insulina. Os autores apresentam uma revisão da abordagem terapêutica da diabetes mellitus tipo 2, dando especial destaque às possíveis reações cutâneas adversas aos hipoglicemiantes que hoje em dia temos ao nosso dispor. A pesquisa bibliográfica foi realizada através de ferramentas eletrónicas de pesquisa avançada e não avançada das seguintes fontes de dados: PubMed e Cochrane Library. Os artigos citados foram considerados os mais relevantes.info:eu-repo/semantics/publishedVersio

    Developing a site-conditions map for seismic hazard Assessment in Portugal

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    The evaluation of site effects on a broad scale is a critical issue for seismic hazard and risk assessment, land use planning and emergency planning. As characterization of site conditions based on the shear-wave velocity has become increasingly important, several methods have been proposed in the literature to estimate its average over the first thirty meters (Vs30) from more extensively available data. These methods include correlations with geologic-geographic defined units and topographic slope. In this paper we present the first steps towards the development of a site–conditions map for Portugal, based on a regional database of shear-wave velocity data, together with geological, geographic, and lithological information. We computed Vs30 for each database site and classified it according to the corresponding geological-lithological information using maps at the smallest scale available (usually 1:50000). We evaluated the consistency of Vs30 values within generalized-geological classes, and assessed the performance of expedient methodologies proposed in the literature

    Imaging 3D seismic velocity along the seismogenic zone of Algarve region (southern Portugal)

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    The present seismic tomographic study is focused around Algarve region, in South of Portugal. To locate the seismic events and find the local velocity structure of epicentral area, the P and S arrival times at 38 stations are used. The data used in this study were obtained during the Algarve campaign which worked from January/2006 to July/2007. The preliminary estimate of origin times and hypocentral coordinates are determined by the Hy- poinverse program. Linearized inversion procedure was applied to comprise the following two steps: 1) finding the minimum 1D velocity model using Velest and 2) simultaneous relocation of hypocenters and determination of local velocity structure. The velocity model we have reached is a 10 layer model which gave the lowest RMS, after several runnings of eight different velocity models that we used “a priori”. The model parameterization assumes a continuous velocity field between 4.5 km/s and 7.0 km/s until 30 km depth. The earth structure is represented in 3D by velocity at discrete points, and velocity at any intervening point is determined by linear interpolation among the surrounding eight grid points. A preliminary analysis of the resolution capabilities of the dataset, based on the Derivative Weight Sum (DWS) distribution, shows that the velocity structure is better resolved in the West part of the region between the surface to15 km. The resulting tomographic image has a prominent low-velocity anomaly that shows a maximum decrease in P-wave velocity in the first 12 kms in the studied region. We also identified the occurrence of local seismic events of reduced magnitude not catalogued, in the neighbourhood of Almodôvar (low Alentejo). The spatial distribution of epicentres defines a NE-SW direction that coincides with the strike of the mapped geological faults of the region and issued from photo-interpretation. Is still expectable to refine the seismicity of the region of Almodôvar and establish more rigorously its role in the seismotectonic picture of the region. This work is expected to produce a more detailed knowledge of the structure of the crust over the region of Algarve, being able to identify seismogenic zones, potentially generators of significant seismic events and also the identification of zones of active faults

    Modeling electrodialysis and a photochemical process for their integration in saline wastewater treatment.

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    Oxidation processes can be used to treat industrial wastewater containing non-biodegradable organic compounds. However, the presence of dissolved salts may inhibit or retard the treatment process. In this study, wastewater desalination by electrodialysis (ED) associated with an advanced oxidation process (photo-Fenton) was applied to an aqueous NaCl solution containing phenol. The influence of process variables on the demineralization factor was investigated for ED in pilot scale and a correlation was obtained between the phenol, salt and water fluxes with the driving force. The oxidation process was investigated in a laboratory batch reactor and a model based on artificial neural networks was developed by fitting the experimental data describing the reaction rate as a function of the input variables. With the experimental parameters of both processes, a dynamic model was developed for ED and a continuous model, using a plug flow reactor approach, for the oxidation process. Finally, the hybrid model simulation could validate different scenarios of the integrated system and can be used for process optimization

    TRANSIENT KNICKPOINTS” NO LEITO DOS RIOS, SIGNIFICADO NA EVOLUÇÃO DA PAISAGEM

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    Neste trabalho apresenta-se uma síntese sobre a relevância dos knickpoints na estruturação do perfil longitudinal dos rios e indirectamente, na evolução da paisagem. Aborda-se o significado dos knickpoints relativamente aos conceitos de equilíbrio e desequilíbrio do perfil longitudinal, difundidos na literatura. Leis que regem a incisão fluvial, testadas em modelos físico-matemáticos, estabelecidos nas duas últimas décadas, são também referidas. Salientam-se as potencialidades que decorrem deste tipo de análise quantitativa dos perfis longitudinais dos rios, nomeadamente: a identificação de troços relíquia e troços ajustados a novas condições de equilíbrio; a reconstituição de antigos leitos (erodidos) a jusante de knickpoints transitórios e a correlação com outras unidades geomorfológicas, como sejam os terraços fluviais. A relação entre o comportamento das vagas de erosão com a morfologia dos knickpoints e com certos modelos de evolução da paisagem é salientada neste trabalho
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