We are concerned with forward wave motion simulations in two-dimensional elastic, heterogeneous, semi-infinite media. We use Perfectly Matched Layers (PMLs) to truncate the semi-infinite extent of the physical domain to arrive at a finite computational domain. We use a recently developed hybrid formulation, where the Navier equations for the interior domain are coupled with a mixed formulation for an unsplit-field PML. Here, we implement the hybrid formulation using spectral elements, and report on its performance. The motivation stems from the following considerations: Of concern is the long-time instability that has been reported even in homogeneous and isotropic cases, when the standard complex-stretching function is used in the PML. The onset of the instability is always within the PML zone, and it manifests as error growth in time. It has been suggested that the instability arises when waves impinge at grazing angle on the PML-interior domain interface. Yet, the instability does not always appear. Furthermore, different values of the various PML parameters (mesh density, attenuation strength, order of attenuation function, etc) can either hinder or delay the onset of the instability. It is thus conjectured that the instability is associated with the spectral properties of the discrete operators. In this thesis, we report numerical results based on both Lagrange interpolants, and results based on spectral elements. Spectral elements are explored since they lead to diagonal mass matrices, have improved dispersion error, and, more importantly, have different spectral properties than Lagrangian-based finite elements. Spectral elements are thus used in an attempt to explore whether the reported instability issues could be alleviated. We design numerical experiments involving explosive sources situated at varying depths from the surface, capable of inducing grazing-angle waves. We use the energy decay as the primary metric for reporting the results of comparisons between various spectral element orders and classical Lagrange interpolants. We also report the results of parametric studies. Overall, it is shown that the spectral elements alone are not capable of removing the instability, though, on occasion, they can. Careful parameterization of the PML could also either remove it or alleviate it. The issue remains open. / text

Bending loss in silicon-on-insulator rib waveguides was calculated using conformal mapping of the curved waveguide to an equivalent straight waveguide. Finite-element analysis with perfectly matched layer boundaries was used to solve the vector wave equation. Transmission loss was experimentally measured as a function of bend radius for several SOI waveguides. Good agreement was found between simulated and measured losses, and this technique was confirmed as a good predictor for loss and for minimum bend radius for efficient design.

This thesis investigates the problem of interaction of electromagnetic radiation with human tissues. A Finite Difference Time Domain (FDTD) code has been developed to model a cellular phone radiating in the presence of a human head. In order to implement the code, FDTD difference equations have been solved in a computational domain truncated by a Perfectly Matched Layer (PML). Specific Absorption Rate (SAR) calculations have been carried out to study safety issues in mobile communication.

No description available.

The finite-difference time-domain (FDTD) method is one of most widely used computational electromagnetics (CEM) methods to solve the Maxwell's equations for modern engineering problems. In biomedical applications, like the microwave imaging for early disease detection and treatment, the human tissues are considered as lossy and dispersive materials. The most popular model to describe the material properties of human body is the Debye model. In order to simulate the computational domain as an open region for biomedical applications, the complex-frequency-shifted perfectly matched layers (CFS-PML) are applied to absorb the outgoing waves. The CFS-PML is highly efficient at absorbing the evanescent or very low frequency waves. This thesis investigates the stability of the CFS-PML and presents some conditions to determine the parameters for the one dimensional and two dimensional CFS-PML.The advantages of the FDTD method are the simplicity of implementation and the capability for various applications. However the Courant-Friedrichs-Lewy (CFL) condition limits the temporal size for stable FDTD computations. Due to the CFL condition, the computational efficiency of the FDTD method is constrained by the fine spatial-temporal sampling, especially in the simulations with the electrically small objects or dispersive materials. Instead of modifying the explicit time updating equations and the leapfrog integration of the conventional FDTD method, the spatial filtered FDTD method extends the CFL limit by filtering out the unstable components in the spatial frequency domain. This thesis implements filtered FDTD method with CFS-PML and one-pole Debye medium, then introduces a guidance to optimize the spatial filter for improving the computational speed with desired accuracy.

No description available.

Made available in DSpace on 2014-06-12T18:02:20Z (GMT). No. of bitstreams: 2 arquivo3641_1.pdf: 6593022 bytes, checksum: 0f5771c7ba5a598c9b448775b9fef6c4 (MD5) license.txt: 1748 bytes, checksum: 8a4605be74aa9ea9d79846c1fba20a33 (MD5) Previous issue date: 2009 / Conselho Nacional de Desenvolvimento Científico e Tecnológico / A leucemia promielocítica aguda (LPA) corresponde a cerca de 20-28% das LMAs nos países latino-americanos, sendo caracterizada pelo acúmulo de células leucêmicas na medula óssea semelhantes a promielócitos e clinicamente associada à coagulopatia, que é responsável pela alta mortalidade precoce nas fases iniciais de tratamento. Apesar da LPA ser geralmente reconhecida por seus caracteres morfológicos, existem casos atípicos. A LPA é uma patologia beneficiada pelo tratamento com ATRA e, portanto, um rápido e eficiente diagnóstico é essencial. A citogenética em geral e a RT-PCR são amplamente utilizadas na detecção da fusão gênica PML-RARα. Estas técnicas fornecem informações adicionais sobre a presenca de outras anormalidades citogenéticas, porém consomem tempo e requerem laboratórios especializados. O padrão da PML provou-se útil ao diagnostico da LPA clássica através de técnicas imunológicas utilizando anticorpos monoclonais ou policlonais. Neste estudo foram analisados 15 pacientes, de ambos os sexos, idade variando de 4 a 17 anos, diagnosticados com LPA no Centro de Oncohematologia Pediátrica do HUOC ou Instituto Nacional do Câncer entre os anos de 2004 a 2008. As amostras de medula óssea dos pacientes foram tratadas de acordo com protocolos padrões sendo realizadas as técnicas de bandeamento G, RT-PCR, FISH usando sonda para o rearranjo PML-RARα e imunofluorescência com anticorpo monoclonal PG-M3. A análise por bandeamento G revelou alterações cromossômicas, com excessão de dois casos que apresentaram cariótipos normais. O estudo apresentou: um cariótipo complexo 47,XX,del(12p),add(14q),del(15q),i(19q),+mar, onde não foi detectada a fusão PML-RARα pela RT-PCR, nem pela FISH; um 48,XX,+2mar, no qual também não foi detectada a fusão PMLRARα pelas técnicas moleculares. Estes dois casos podem conter fusões variantes. Sete casos com t(15;17) foram detectados pela citogenética e confirmados pela FISH; cinco casos com t(15;17) confirmados pela FISH quando não foi possível realizar a análise citogenética. Em três casos a RT-PCR mostrou-se divergente da FISH. A imunofluorescência foi realizada em cinco casos e todos confirmaram o diagnóstico da LPA clássica. Sete pacientes estão vivos, seis em remissão, um em tratamento e oito foram a óbito. Estes dados mostram a importância da união de diversas metodologias para o aperfeiçoamento da eficiência e sensibilidade do diagnóstico e do tratamento desta doença

Made available in DSpace on 2014-06-12T18:02:56Z (GMT). No. of bitstreams: 2 arquivo8119_1.pdf: 4127441 bytes, checksum: 536d2a1ed26f87f1fd0b557a427a3ee2 (MD5) license.txt: 1748 bytes, checksum: 8a4605be74aa9ea9d79846c1fba20a33 (MD5) Previous issue date: 2006 / O turismo é um segmento econômico que exige atenção quanto a sua contribuição para o desenvolvimento sustentável, principalmente pelos impactos econômicos, sociais e ambientais. Esta pesquisa objetiva analisar o potencial de contribuição da Produção Mais Limpa (PML) nos meios de hospedagem de Porto de Galinhas como instrumento de turismo sustentável em apoio à implementação da Agenda 21 do Município de Ipojuca-PE. O estudo foi elaborado a partir de 3 fases, a saber: Fase I, diagnóstico em 13 meios de hospedagem de Porto de Galinhas; Fase II, entrega de relatórios as empresas participantes e orientação para implementação das ações; e, Fase III, aferição de resultados nas empresas. Este trabalho de campo foi conduzido no período de junho a novembro de 2005. Para tal, a pesquisa se desenvolve através das seguintes ações: (1) elaboração de um quadro referencial do desenvolvimento sustentável aplicado à atividade turística; (2) identificação das relações entre as propostas da Agenda 21 de Ipojuca e a metodologia de PML; (3) diagnóstico do potencial de implementação dos passos previstos na PML nos meios de hospedagem de Porto de Galinhas; (4) desenvolvimento de um quadro comparativo entre os programas ambientais existentes e a PML em relação aos princípios do turismo sustentável; e (5) propostas de alternativas para efetiva implementação de PML nos meios de hospedagem. Os resultados alcançados foram bastante positivos, pois o conhecimento do perfil dos meios de hospedagem de Porto de Galinhas permitiu a confirmação da potencialidade do setor hoteleiro em agir pró-ativamente em relação às estratégias da Agenda 21 de Ipojuca. Isto enfatiza que o setor pode e deve contribuir para o desenvolvimento do turismo sustentável

L'ataxie spinocérébelleuse de type 7 (SCA7) est une maladie neurodégénerative due à une expansion de CAG traduit en polyQ dans la protéine ataxine-7. La SUMOylation, modification post-traductionnelle que nous avons identifiée moduler l'agrégation de la protéine mutante, est facilitée par une SUMO E3 ligase.Nous avons identifié RanBP2, une nucléoporine appartenant au complexe du pore nucléaire en tant que SUMO E3 ligase, via SUMO-1 de l'ataxine-7. En effet, le silencing de RanBP2 induit l'agrégation de l'ataxine-7 mutante, ce qui démontre l'implication de RanBP2 dans la physiopathologie de SCA7. Nous montrons également que l'ataxine-7 endogène est une cible modifiée par SUMO-1 et -2. L'ataxine-7 poly-SUMOylée, grâce à la présence de chaines SUMO2/3, est capable de recruter RNF4. Cette protéine conduit à la dégradation de l'ataxine-7 mutante par la voie du protéasome. La dégradation est abolie en présence d'un mutant de RNF4.Dans un modèle murin KI SCA7, nous avons quantifié l'expression des gènes impliqués dans la voie de la SUMOylation au niveau des régions les plus touchées du cerveau. Le niveau d'expression des ARNs messagers montre des altérations dépendantes des répétitions CAG du gène SCA7. A 6 mois (avant le début de la pathologie), les premières dérégulations sont observées; à 12 mois (à un stade avancé de la maladie), on note une diminution statistiquement significative de Sumo-1 dans le cervelet des souris Atxn7100Q/5Q. Ces résultats, alliés à l'observation de l'accumulation anormale des protéines SUMO-1 et RanBP2 dans le cervelet d'un patient SCA7, suggèrent que les voies de la SUMOylation in vivo peuvent être perturbées dans SCA7. / Spinocerebellar ataxia type 7 (SCA7) is a neurodegenerative disease caused by a CAG expansion (polyQ) in the protein ataxin-7. SUMOylation, a post-translational modification that we identified to modulate mutant protein aggregation in a SCA7 cellular model, is facilitated by a SUMO E3 ligase. Here, we identified RanBP2 (Nup358), a nucleoporin belonging to the nuclear pore complex, as the major E3 enzyme implicated in ataxin-7 modification by SUMO-1. Indeed, RanBP2 silencing renders mutant ataxin-7 more prone to aggregation, thus demonstrating the implication of RanBP2 in SCA7 pathophysiology. We also show that endogenous ataxin-7 is a target for both SUMO-1 and -2 modification. Poly-SUMOylated ataxin-7 presents a docking site composed of SUMO2/3 chains for the recruitment of RNF4: this protein is a SUMO E3 ubiquitin ligase that mediates degradation of mutant ataxin-7 by the proteasome pathway. The degradation is abolished in presence of a mutant form of RNF4. In a SCA7 knock-in mouse model we quantified expression of SUMO-pathway related genes in cerebellum and retina, the most affected regions using quantitative RT-PCR. SUMO-related genes show expanded repeat-dependent alterations in expression patterns. At 6 months (before onset), deregulations begin to occur; by 12 months (late stage of disease), there is a statistically significant impairment in Sumo-1 levels in Atxn7100Q/5Q cerebellum. These results, together with the observation that SUMO-1 and RanBP2 protein accumulate abnormally in the cerebellum of a SCA7 patient, suggest that in vivo SUMO-modifying pathways may be perturbed in SCA7.

No description available.