941 resultados para Nonlinear functional analysis


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Dissertação de Mestrado em Finanças Empresariais

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Mestrado em Engenharia Electrotécnica e de Computadores. Área de Especialização de Telecomunicações.

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Trabalho Final de Mestrado para obtenção do grau de Mestre em Engenharia Civil na Área de Especialização de Estruturas

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Trabalho Final de Mestrado para obtenção do grau de Mestre em Engenharia Civil

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Gravity loads can affect a reinforced concrete structure's response to seismic actions, however, traditional procedures for testing the beam behaviour do not take this effect into consideration. An experimental campaign was carried out in order to assess the influence of the gravity load on RC beam connection to the column subjected to cyclic loading. The experiments included the imposition of a conventional quasi-static test protocol based on the imposition of a reverse cyclic displacement history and of an alternative cyclic test procedure starting from the gravity load effects. The test results are presented, compared and analysed in this paper. The imposition of a cyclic test procedure that included the gravity loads effects on the RC beam ends reproduces the demands on the beams' critical zones more realistically than the traditional procedure. The consideration of the vertical load effects in the test procedure led to an accumulation of negative (hogging) deformation. This phenomenon is sustained with the behaviour of a portal frame system under cyclic loads subject to a significant level of the vertical load, leading to the formation of unidirectional plastic hinges. In addition, the hysteretic behaviour of the RC beam ends tested was simulated numerically using the nonlinear structural analysis software - OpenSees. The beam-column model simulates the global element behaviour very well, as there is a reasonable approximation to the hysteretic loops obtained experimentally. (C) 2013 Elsevier Ltd. All rights reserved.

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Este trabalho académico surge no âmbito da realização da dissertação do Mestrado em Engenharia e Gestão Industrial. Tem como objetivo a melhoria da gestão do Departamento de Infraestruturas, numa empresa de produção de motores elétricos para a indústria automóvel, através da análise, implementação e melhoria de um software de gestão de manutenção, de forma a aumentar a eficiência do Departamento. Este estudo foi desenvolvido durante um estágio curricular na empresa Globe Motors Portugal Lda, localizada em Vila do Conde. Para sua sustentação, foi efetuada uma análise funcional, suportada por um Software de gestão de manutenção, de forma a perceber qual a importância que o mesmo tem no funcionamento do Departamento de Infraestruturas. Pretendeu-se compreender quais as vantagens e desvantagens da sua utilização. Posteriormente, implementou-se uma nova versão deste software, analisando-se os pontos fortes e as oportunidades de melhoria, de forma a tornar o Departamento de infraestruturas mais eficiente, através da utilização desta renovada ferramenta de trabalho. Como objetivo último, pretendeu-se à melhoria da organização e gestão do Departamento de infraestruturas, contribuindo para um desenvolvimento de toda a empresa, uma vez que comungamos a ideia de que só é possível ser competitivo, num mercado altamente exigente, através de processos eficientes, possibilitando a redução de custos a todos os níveis.

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Dissertação de Mestrado apresentada ao Instituto de Contabilidade e Administração do Porto para a obtenção do grau de Mestre em Tradução e Interpretação Especializadas, sob orientação do Doutor Manuel Moreira da Silva Esta versão não contém as críticas e sugestões dos elementos do júri

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The paper presented herein proposes a reliability-based framework for quantifying the structural robustness considering the occurrence of a major earthquake (mainshock) and subsequent cascading hazard events, such as aftershocks that are triggered by the mainshock. These events can significantly increase the probability of failure of buildings, especially for structures that are damaged during the mainshock. The application of the proposed framework is exemplified through three numerical case studies. The case studies correspond to three SAC steel moment frame buildings of 3-, 9-, and 20- stories, which were designed to pre-Northridge codes and standards. Twodimensional nonlinear finite element models of the buildings are developed using the Open System for Earthquake Engineering Simulation framework (OpenSees), using a finite-length plastic hinge beam model and a bilinear constitutive law with deterioration, and are subjected to multiple mainshock-aftershock seismic sequences. For the three buildings analyzed herein, it is shown that the structural reliability under a single seismic event can be significantly different from that under a sequence of seismic events. The reliability-based robustness indicator used shows that the structural robustness is influenced by the extent by which a structure can distribute damage.

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INTRODUCTION: Toxoplasmosis is usually a benign infection, except in the event of ocular, central nervous system (CNS), or congenital disease and particularly when the patient is immunocompromised. Treatment consists of drugs that frequently cause adverse effects; thus, newer, more effective drugs are needed. In this study, the possible activity of artesunate, a drug successfully being used for the treatment of malaria, on Toxoplasma gondii growth in cell culture is evaluated and compared with the action of drugs that are already being used against this parasite. METHODS: LLC-MK2 cells were cultivated in RPMI medium, kept in disposable plastic bottles, and incubated at 36ºC with 5% CO2. Tachyzoites of the RH strain were used. The following drugs were tested: artesunate, cotrimoxazole, pentamidine, pyrimethamine, quinine, and trimethoprim. The effects of these drugs on tachyzoites and LLC-MK2 cells were analyzed using nonlinear regression analysis with Prism 3.0 software. RESULTS: Artesunate showed a mean tachyzoite inhibitory concentration (IC50) of 0.075µM and an LLC MK2 toxicity of 2.003µM. Pyrimethamine was effective at an IC50 of 0.482µM and a toxicity of 11.178µM. Trimethoprim alone was effective against the in vitro parasite. Cotrimoxazole also was effective against the parasite but at higher concentrations than those observed for artesunate and pyrimethamine. Pentamidine and quinine had no inhibitory effect over tachyzoites. CONCLUSIONS: Artesunate is proven in vitro to be a useful alternative for the treatment of toxoplasmosis, implying a subsequent in vivo effect and suggesting the mechanism of this drug against the parasite.

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 The success of synthetic bone implants requires good interface between the material and the host tissue. To study the biological relevance of fi bronectin (FN) density on the osteogenic commitment of human bone marrow mesenchymal stem cells (hBMMSCs), human FN was adsorbed in a linear density gradient on the surface of PCL. The evolution of the osteogenic markers alkaline phosphatase and collagen 1 alpha 1 was monitored by immunohistochemistry, and the cytoskeletal organization and the cell-derived FN were assessed. The functional analysis of the gradient revealed that the lower FN-density elicited stronger osteogenic expression and higher cytoskeleton spreading, hallmarks of the stem cell commitment to the osteoblastic lineage. The identifi cation of the optimal FN density regime for the osteogenic commitment of hBM-MSCs presents a simple and versatile strategy to signifi cantly enhance the surface properties of polycaprolactone as a paradigm for other synthetic polymers intended for bone-related applications.

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Tese de Doutoramento em Engenharia Civil

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Abstract Background: Right-sided heart failure has high morbidity and mortality, and may be caused by pulmonary arterial hypertension. Fractal dimension is a differentiated and innovative method used in histological evaluations that allows the characterization of irregular and complex structures and the quantification of structural tissue changes. Objective: To assess the use of fractal dimension in cardiomyocytes of rats with monocrotaline-induced pulmonary arterial hypertension, in addition to providing histological and functional analysis. Methods: Male Wistar rats were divided into 2 groups: control (C; n = 8) and monocrotaline-induced pulmonary arterial hypertension (M; n = 8). Five weeks after pulmonary arterial hypertension induction with monocrotaline, echocardiography was performed and the animals were euthanized. The heart was dissected, the ventricles weighed to assess anatomical parameters, and histological slides were prepared and stained with hematoxylin/eosin for fractal dimension analysis, performed using box-counting method. Data normality was tested (Shapiro-Wilk test), and the groups were compared with non-paired Student t test or Mann Whitney test (p < 0.05). Results: Higher fractal dimension values were observed in group M as compared to group C (1.39 ± 0.05 vs. 1.37 ± 0.04; p < 0.05). Echocardiography showed lower pulmonary artery flow velocity, pulmonary acceleration time and ejection time values in group M, suggesting function worsening in those animals. Conclusion: The changes observed confirm pulmonary-arterial-hypertension-induced cardiac dysfunction, and point to fractal dimension as an effective method to evaluate cardiac morphological changes induced by ventricular dysfunction.

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Splenic marginal zone lymphoma (SMZL) is a low grade B-cell non-Hodgkin's lymphoma. The molecular pathology of this entity remains poorly understood. To characterise this lymphoma at the molecular level, we performed an integrated analysis of 1) genome wide genetic copy number alterations 2) gene expression profiles and 3) epigenetic DNA methylation profiles.We have previously shown that SMZL is characterised by recurrent alterations of chromosomes 7q, 6q, 3q, 9q and 18; however, gene resolution oligonucleotide array comparative genomic hybridisation did not reveal evidence of cryptic amplification or deletion in these regions. The most frequently lost 7q32 region contains a cluster of miRNAs. qRT-PCR revealed that three of these (miR-182/96/183) show underexpression in SMZL, and miR-182 is somatically mutated in >20% of cases of SMZL, as well as in >20% of cases of follicular lymphoma, and between 5-15% of cases of chronic lymphocytic leukaemia, MALT-lymphoma and hairy cell leukaemia. We conclude that miR-182 is a strong candidate novel tumour suppressor miRNA in lymphoma.The overall gene expression signature of SMZL was found to be strongly distinct fromthose of other lymphomas. Functional analysis of gene expression data revealed SMZL to be characterised by abnormalities in B-cell receptor signalling (especially through the CD19/21-PI3K/AKT pathway) and apoptotic pathways. In addition, genes involved in the response to viral infection appeared upregulated. SMZL shows a unique epigenetic profile, but analysis of differentially methylated genes showed few with methylation related transcriptional deregulation, suggesting that DNA methylation abnormalities are not a critical component of the SMZL malignant phenotype.

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NR2E3, a photoreceptor-specific nuclear receptor (PNR), represses cone-specific genes and activates several rod-specific genes. In humans, mutations in NR2E3 have been associated with the recessively-inherited enhanced short-wavelength sensitive S-cone syndrome (ESCS) and, recently, with autosomal dominant (ad) retinitis pigmentosa (RP) (adRP). In the present work, we describe two additional families affected by adRP that carry a heterozygous c.166G&gt;A (p.G56R) mutation in the NR2E3 gene. Functional analysis determined the dominant negative activity of the p.G56R mutant protein as the molecular mechanism of adRP. Interestingly, in one pedigree, the most common causal variant for ESCS (p.R311Q) cosegregated with the adRP-linked p.G56R mutation, and the compound heterozygotes exhibited an ESCS-like phenotype, which in 1 of the 2 cases was strikingly "milder" than the patients carrying the p.G56R mutation alone. Impaired repression of cone-specific genes by the corepressors atrophin-1 (dentatorubral-pallidoluysian atrophy [DRPLA] gene product) and atrophin-2 (arginine-glutamic acid dipeptide repeat [RERE] protein) appeared to be a molecular mechanism mediating the beneficial effect of the p.R311Q mutation. Finally, the functional dominance of the p.R311Q variant to the p.G56R mutation is discussed.

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A structural and functional analysis of the 5'-end region of the Xenopus laevis vitellogenin gene A1 revealed two transcription initiation sites located 1.8 kilobases apart. A RNA polymerase II binding assay indicates that both promoters form initiation complexes efficiently. In vitro, using a transcription assay derived from a HeLa whole-cell extract, the upstream promoter is more than 10-fold stronger than the downstream one. In contrast, both promoters have a similar strength in a HeLa nuclear extract. In vivo, that is in estrogen-stimulated hepatocytes, it is the downstream promoter homologous to the one used by the other members of the vitellogenin gene family, which is 50-fold stronger than the upstream promoter. Thus, if functional vitellogenin mRNA results from this latter activity, it would contribute less than 1% to the synthesis of vitellogenin by fully induced Xenopus hepatocytes expressing the four vitellogenin genes. In contrast, both gene A1 promoters are silent in uninduced hepatocytes. Transfection experiments using the Xenopus cell line B3.2 in which estrogen-responsiveness has been introduced reveal that the strong downstream promoter is controlled by an estrogen responsive element (ERE) located 330 bp upstream of it. The upstream promoter can also be controlled by the same ERE. Since the region comprising the upstream promoter is flanked by a 200 base pair long inverted repeat with stretches of homology to other regions of the X. laevis genome, we speculate that it might have been inserted upstream of the vitellogenin gene A1 by a recombination event and consequently brought under control of the ERE lying 1.5 kilobases downstream.