In large scale productions of metal sheets, it is important to maintain an effective way to continuously inspect the products passing through the production line. The inspection mainly consists of detection of defects and tracking of ID numbers. This thesis investigates the possibilities to create an automatic inspection system by evaluating different machine learning algorithms for defect detection and optical character recognition (OCR) on metal sheet data. Digit recognition and defect detection are solved separately, where the former compares the object detection algorithm Faster R-CNN and the classical machine learning algorithm NCGF, and the latter is based on unsupervised learning using a convolutional autoencoder (CAE). The advantage of the feature extraction method is that it only needs a couple of samples to be able to classify new digits, which is desirable in this case due to the lack of training data. Faster R-CNN, on the other hand, needs much more training data to solve the same problem. NCGF does however fail to classify noisy images and images of metal sheets containing an alloy, while Faster R-CNN seems to be a more promising solution with a final mean average precision of 98.59%. The CAE approach for defect detection showed promising result. The algorithm learned how to only reconstruct images without defects, resulting in reconstruction errors whenever a defect appears. The errors are initially classified using a basic thresholding approach, resulting in a 98.9% accuracy. However, this classifier requires supervised learning, which is why the clustering algorithm Gaussian mixture model (GMM) is investigated as well. The result shows that it should be possible to use GMM, but that it requires a lot of GPU resources to use it in an end-to-end solution with a CAE.

Doenças cardíacas congênitas são as mais frequentes entre as malformações congênitas graves, afetando de duas a três crianças por 100 nascidos vivos, sendo o defeito do septo atrioventricular (DSAV) responsável por 5% desses, e atingindo cerca de 50% dos pacientes portadores de Síndrome de Down. Caracteriza-se essencialmente por vários graus de desenvolvimento incompleto do tecido septal ao redor das valvas atrioventriculares, bem como de anormalidades na formação das mesmas. Recomenda-se a correção cirúrgica ao redor de 4 meses de vida, no intuito de prevenir o surgimento de hipertensão pulmonar (HP) irreversível devida ao hiperfluxo pulmonar, no entanto a despeito disso, identifica-se a presença de hipertensão pulmonar em pacientes já submetido ä correção do defeito cardíaco. O presente estudo teve por objetivo analisar a prevalência de hipertensão pulmonar diagnosticada através do ecocardiografia e identificar dos fatores de risco em pacientes submetidos à correção cirúrgica de DSAV nos últimos 16 anos no Hospital das Clínicas da Faculdade de Medicina de Ribeirão preto da Universidade de São Paulo (HCFMRP - USP). Foram selecionados pacientes portadores de DSAV, submetidos à correção cirúrgica no HCFMRP - USP, no período de janeiro de 1999 a janeiro de 2016, em seguimento no Ambulatório de Cardiologia Infantil do HCFMRP-USP, considerados portadores de hipertensão pulmonar os pacientes que apresentaram à ecocardiografia valores estimados de pressão sistólica de artéria pulmonar (PSAP) superiores a 30 mmHg. Foram analisadas variáveis clínicas pré e pós-operatórias. Não foi encontrada correlação entre peso e idade na data da correção cirúrgica e presença de HP na avaliação ecocardiográfica pós-operatória; no entanto esta se relacionou com tempo prolongado de circulação extra-corpórea e ventilação mecânica. Houve aumento significativo na sobrevida nos últimos oito anos analisados, refletindo a melhoria na qualidade de atendimento clinico e cirúrgico dos pacientes. A alta perda de seguimento ambulatorial causa preocupação, porém reflete as dificuldades próprias de serviços de saúde de países em desenvolvimento. / Congenital heart diseases are the most common serious congenital malformations, affecting two of three children per 100 newborns, the atrioventricular septal defect (AVSD) is responsible for 5% of these cases, reaching almost 50% of bearers of Down\'s Syndrome. It has been characterized essentially by many incomplete development degrees of de septal tissue around the atrioventricular valves, as well as its formation abnormalities. The actual recommendation is to proceed surgical correction nearly 4 months of age, in order to prevent irreversible pulmonary hypertension (PH) due to the pulmonary overflow. Despite of the surgical correction, patients may present pulmonary hypertension. This research aimed to analyze the prevalence of pulmonary hypertension diagnosed by transthoracic echocardiogram and identify risk factors for this outcome in patients undergoing surgical correction of AVSD in the last 16 years at the Hospital das Clínicas da Faculdade de Medicina de Ribeirão Preto da Universidade de São Paulo (HCFMRP - USP). All patients diagnosed with AVSD, submitted to surgical correction and followed at the HCFMRP - USP in the last 16 years and were selected. Those who had systolic pulmonary arterial pressure above 30 mmHg in the echocardiogram evaluation were considered to have pulmonary hypertension. Clinical variables before and after surgery were analyzed. Anthropometric and age data at the surgery had no influence in the presence of PH in the follow up. Although prolonged cardiopulmonary bypass and pulmonary mechanical ventilation had significantly affected that outcome. The survival had increased significantly in the last eight years of our study, reflecting the improvement of assistance. A high loss of follow up was detected and made us very concerned, however shows the difficulties and low investment in the public health system in developing countries.

No description available.

Doenças cardíacas congênitas são as mais frequentes entre as malformações congênitas graves, afetando de duas a três crianças por 100 nascidos vivos, sendo o defeito do septo atrioventricular (DSAV) responsável por 5% desses, e atingindo cerca de 50% dos pacientes portadores de Síndrome de Down. Caracteriza-se essencialmente por vários graus de desenvolvimento incompleto do tecido septal ao redor das valvas atrioventriculares, bem como de anormalidades na formação das mesmas. Recomenda-se a correção cirúrgica ao redor de 4 meses de vida, no intuito de prevenir o surgimento de hipertensão pulmonar (HP) irreversível devida ao hiperfluxo pulmonar, no entanto a despeito disso, identifica-se a presença de hipertensão pulmonar em pacientes já submetido ä correção do defeito cardíaco. O presente estudo teve por objetivo analisar a prevalência de hipertensão pulmonar diagnosticada através do ecocardiografia e identificar dos fatores de risco em pacientes submetidos à correção cirúrgica de DSAV nos últimos 16 anos no Hospital das Clínicas da Faculdade de Medicina de Ribeirão preto da Universidade de São Paulo (HCFMRP - USP). Foram selecionados pacientes portadores de DSAV, submetidos à correção cirúrgica no HCFMRP - USP, no período de janeiro de 1999 a janeiro de 2016, em seguimento no Ambulatório de Cardiologia Infantil do HCFMRP-USP, considerados portadores de hipertensão pulmonar os pacientes que apresentaram à ecocardiografia valores estimados de pressão sistólica de artéria pulmonar (PSAP) superiores a 30 mmHg. Foram analisadas variáveis clínicas pré e pós-operatórias. Não foi encontrada correlação entre peso e idade na data da correção cirúrgica e presença de HP na avaliação ecocardiográfica pós-operatória; no entanto esta se relacionou com tempo prolongado de circulação extra-corpórea e ventilação mecânica. Houve aumento significativo na sobrevida nos últimos oito anos analisados, refletindo a melhoria na qualidade de atendimento clinico e cirúrgico dos pacientes. A alta perda de seguimento ambulatorial causa preocupação, porém reflete as dificuldades próprias de serviços de saúde de países em desenvolvimento. / Congenital heart diseases are the most common serious congenital malformations, affecting two of three children per 100 newborns, the atrioventricular septal defect (AVSD) is responsible for 5% of these cases, reaching almost 50% of bearers of Down\'s Syndrome. It has been characterized essentially by many incomplete development degrees of de septal tissue around the atrioventricular valves, as well as its formation abnormalities. The actual recommendation is to proceed surgical correction nearly 4 months of age, in order to prevent irreversible pulmonary hypertension (PH) due to the pulmonary overflow. Despite of the surgical correction, patients may present pulmonary hypertension. This research aimed to analyze the prevalence of pulmonary hypertension diagnosed by transthoracic echocardiogram and identify risk factors for this outcome in patients undergoing surgical correction of AVSD in the last 16 years at the Hospital das Clínicas da Faculdade de Medicina de Ribeirão Preto da Universidade de São Paulo (HCFMRP - USP). All patients diagnosed with AVSD, submitted to surgical correction and followed at the HCFMRP - USP in the last 16 years and were selected. Those who had systolic pulmonary arterial pressure above 30 mmHg in the echocardiogram evaluation were considered to have pulmonary hypertension. Clinical variables before and after surgery were analyzed. Anthropometric and age data at the surgery had no influence in the presence of PH in the follow up. Although prolonged cardiopulmonary bypass and pulmonary mechanical ventilation had significantly affected that outcome. The survival had increased significantly in the last eight years of our study, reflecting the improvement of assistance. A high loss of follow up was detected and made us very concerned, however shows the difficulties and low investment in the public health system in developing countries.

Made available in DSpace on 2016-04-26T20:20:10Z (GMT). No. of bitstreams: 1 Marina Vieira de Figueiredo.pdf: 1372275 bytes, checksum: a0f9d806e932335566efa19346d5a512 (MD5) Previous issue date: 2011-06-06 / For a rule to be legal, in other words, for it to join the system of positive law, it is essential the fulfillment of certain conditions. Once it entered the legal system, it is assumed that this rule is valid, ie, that it was enacted in accordance with the prescription of its base rule (rule of competence). In fact, we start from the premise that the production of a legal rule arises, always, from the appliance (incidence) of another rule, also legal, being essential that the created rule is subsumed to the rule which bases its creation. The problem is that the rules are not always enacted in accordance with the prescription of the higher rules (primary rules of competence). When the members of the system acknowledge that the rule is flawed that is, it was produced illicitly it is opened room for the application of the penalty provided by the secondary rule of competence: invalidity of the rule illegally created. Being the assessment a general and concrete legal rule which introduces into the system another rule, this one individual and concrete, responsible for the formation of the obligation to pay a specific tax it may have been enacted illegally. The review of the assessment is unveiled exactly when the taxable person, or the Treasury itself, believes that this rule is flawed whether related to the person that produced it, to the followed procedure in its drafting or to its contents (individual and concrete rule due the appliance of the tax incidence-matrix rule). Searching the rules which regulate the review of the assessment, as well as the possible defects to which is subdued, we verify that this not always leads to invalidity (not application) of that rule. We conclude, therefore, that, even if the assessment is claimed to be flawed, it may be: (i) sustained in its exact terms; (ii) refined (convalidation); (iii) or entirely or partially revoked. The review of the assessment, thus, does not always with its effacement from the system / Para que uma norma seja jurídica, ou seja, para que ingresse no sistema de direito positivo, é indispensável o preenchimento de certos requisitos. Uma vez que ingressa no sistema jurídico, presume-se que essa norma é válida, ou seja; que foi produzida de acordo com o que prescreve a regra que a fundamenta (norma de competência). De fato, partimos da premissa de que a produção de uma norma jurídica decorre, sempre, da aplicação (incidência) de outra regra, também jurídica, sendo indispensável que a norma criada se subsuma àquilo que prescreve a norma que fundamenta sua criação. O problema é que nem sempre as normas são produzidas de acordo com o que prescrevem as normas superiores (normas primárias de competência). Quando os integrantes do sistema reconhecem que a norma é defeituosa ou seja, sua produção se deu de maneira ilícita abre-se espaço para a aplicação da sanção prevista na norma secundária de competência: nulidade da norma criada ilicitamente. Sendo o lançamento uma norma jurídica geral e concreta que introduz no sistema outra regra, esta individual e concreta, responsável pela constituição do dever de pagar um determinado tributo é possível que seja produzido de maneira irregular. A revisão do lançamento é inaugurada justamente quando o sujeito passivo do tributo, ou o próprio Fisco, crê que esta norma possui algum vício seja em relação ao sujeito que a produziu, ao procedimento observado na sua confecção ou ao seu conteúdo (norma individual e concreta decorrente da aplicação da regra-matriz de incidência tributária). Pesquisando as disposições que disciplinam a revisão do lançamento, bem como os possíveis vícios a que está sujeito, verificamos que nem sempre acarretam a nulidade (não aplicação) dessa norma. Concluímos, assim, que, ainda que se o lançamento for considerado defeituoso, poderá ser: (i) mantido nos seus exatos termos; (ii) corrigido (convalidação); (iii) ou anulado total ou parcialmente. A revisão do lançamento, portanto, nem sempre culminará com sua supressão do sistema

Le cartilage est un tissu clé des articulations synoviales. Suite à un problème mécanique, traumatique ou inflammatoire, le cartilage est dégradé entrainant des douleurs articulaires et une perte de mobilité. Le cartilage étant un tissu non innervé et non vascularisé, son auto-réparation est très faible. De plus en plus de techniques sont développées pour la réparation des défauts cartilagineux mais aucune n’a encore permis d’obtenir un nouveau cartilage pleinement fonctionnel. En particulier, l’ingénierie tissulaire (IT) est une technique très prometteuse qui consiste à obtenir un greffon de cartilage dont les propriétés mécaniques et structurales soient satisfaisantes une fois implantée dans l’articulation. L’IT est basée sur l’association de cellules, d’un biomatériau et de facteurs de croissance. Le but de cette thèse est d’étudier l’effet de l’âge du donneur des cellules sur la synthèse du greffon par l’IT in vitro et sur la qualité du cartilage obtenu lors de l’implantation dans un modèle de rat NUDE. Puis dans une dernière partie, l’impact de l’environnement chimique et mécanique est étudié sur la qualité du greffon. Nos études montrent ainsi que l’âge du donneur aussi bien dans un contexte in vitro ou in vivo impacte la qualité du greffon et la réparation une fois implanté dans l’animal. En effet, les greffons issus des donneurs âgés ont des propriétés mécaniques légèrement plus élevées et une synthèse des protéines de la matrice extracellulaire (MEC) du cartilage significativement plus élevée que les greffons issus de donneurs jeunes. De plus, la réponse inflammatoire des greffons implantés dans un défaut cartilagineux chez le rat NUDE est plus faible pour les donneurs âgés. Enfin, nous montrons que le microenvironnement mécanique (compression ou pression hydrostatique) et chimique (liquide synovial (LS) ou TGF-β pur) joue un rôle important sur la réponse cellulaire. Par ailleurs, en fonction de l’âge, l’association de ces différents facteurs donnent des résultats différents. Par exemple, pour une sollicitation de type compression, c’est le LS qui est à favoriser pour obtenir les greffons de meilleure qualité dans le cas des donneurs âgés. Au contraire, pour la même sollicitation de type compression, c’est la présence de TGF-β1 qui conduit au greffon de meilleure qualité pour les donneurs jeunes. Ces études mettent en évidence l’importance de l’âge du donneur et montrent de plus qu’un protocole IT patient spécifique est la meilleure solution. / Cartilage is an important tissue of synovial joints. Following a mechanical problem, traumatic or inflammatory, the cartilage is degraded causing joint pain and loss of mobility. Because cartilage is a non-innervated and non-vascularized tissue, its self-repair is very weak. More and more techniques are being developed for the cartilage but none has resulted in a new fully functional cartilage. In particular, tissue engineering (TE) is a very promising technique that consists in obtaining a cartilage graft whose mechanical and structural properties are satisfactory once implanted in the joint. TE is based on the association of cells, biomaterial and growth factors. The aim of this thesis is to study the effect of cell donor’s age on graft synthesis by TE in vitro and on the quality of the cartilage obtained during implantation in a NUDE rat model. Then in a last part, the impact of the chemical and mechanical environment is studied on the quality of the graft. Our studies show that the age of the donor both in vitro and in vivo has an impact on graft quality and repair once implanted in the animal. In fact, grafts from older donors have slightly higher mechanical properties and significantly higher synthesis of extracellular matrix proteins (ECM) than grafts from younger donors. In addition, the inflammatory response of grafts implanted in a cartilage defect in the NUDE rat is lower for older donors. Finally, we show that the mechanical microenvironment (compression or hydrostatic pressure) and chemical microenvironment (synovial fluid (SF) or TGF-β) play an important role in the cellular response. Moreover, depending on age, the combination of these different factors gives different results. For example, for a compression solicitation, it is the SF that is to be favored to obtain better quality grafts in the case of elderly donors. On the contrary, for the same compression stress, it is the presence of TGF-β1 that leads to the best quality graft for young donors. These studies highlight the importance of donor age and further show that a specific patient protocol of TE is the best solution.

This thesis investigated the different aspects and mechanisms of leak-before-break (LBB) assessment. The main objective was to improve the understanding of the transition between surface and through wall defects. While existing procedures generally idealise the through-wall crack into a rectangular shape, in reality a crack propagates with a shape depending on the loading. Comparison between the related solutions from established procedures have been undertaken. The apparent variation depending on the solutions used in the assessment has been highlighted. Two different methodologies have been employed to investigate the transition of flaw: (i) non-ideal through-wall and (ii) surface-breaking flaw propagation. The first approach consists of numerical models of non-idealised flaws in order to assess the effect on LBB parameters. For the second approach, experiments have been first carried out to visualise the shape of defect growths. To further study surface-breaking flaws, both experimental and numerical studies were performed. Fatigue tests on deeply notched plates with two crack aspect ratios were carried out. Strain evolutions on the back surface were recorded along the axes parallel and perpendicular to the crack. Numerical models have been prepared to investigate a larger scope. Behaviour of growing surface-breaking defects was examined. Based on the work conducted in this research, the major findings can be summarised as follows: - The existing solutions to carry out a LBB assessment using available procedures were reviewed and discussed. For axial flaws, SIF solutions were found similar and in good agreement with FEA values. Reference stress solutions showed significant difference between BS 7910 and API 579-1/ASME FFS-1. When compared to experimental data, API's solutions were able to distinguish between leak and break cases. - Flaw geometry assumption for through-wall crack yet to become idealised did not always reflect the actual behaviour, especially for COA calculation. In this case, FEA can be used as a good predictive tool for LBB to estimate margins when assessing leak rate. - The experiment using metallic specimens showed that high stress/strain on back surface would provide a good estimate of the crack propagation as it approached break-through. This offers a more accurate monitoring mechanism. Strain-mapping devices such as gauges could be used.

A redistribuição e ativação elétrica dos dopantes tipo n (As e Sb) e tipo p (Ga e In) em Si com excesso de vacâncias foram analisadas. As vacâncias foram geradas por implantação iônica de altas doses de oxigênio ou nitrogênio em alta temperatura, de acordo com procedimentos já estudados. Em seguida foram implantados os dopantes com dose de 5x1014 cm-2 a 20 keV na região rica em vacâncias. Dopagens idênticas foram realizadas em amostras de Si sem vacâncias e em SIMOX. Em seguida foram feitos recozimentos a 1000ºC por 10 s ou 15 min. Os perfis atômicos dos dopantes foram medidos com Medium Energy Ion Scattering e os perfis dos dopantes ativados, com Hall diferencial. A redistribuição e as propriedades elétricas de cada um dos dopantes no Si sem vacâncias foram bastante similares às observadas no SIMOX, porém várias diferenças foram observadas em relação às amostras com excesso de vacâncias. As vacâncias reduziram a ativação elétrica do As e do Sb, mas proporcionaram maior estabilidade da ativação após recozimentos longos. A redistribuição destes dopantes foi infuenciada pelo íon usado na geração das vacâncias, ou seja, nitrogênio ou oxigênio. O oxigênio proporcionou maior dose retida de As e o nitrogênio, maior dose retida de Sb. Já para o Ga e o In, as vacâncias tiveram papel fundamental na sua redistribuição, diminuindo a difusão para fora das amostras e garantindo maior dose retida. A ativação elétrica do Ga e especialmente a do In foram baixas, onde observamos forte influência do íon pré-implantado, principalmente o oxigênio. / The redistribution and electrical activation of n type (As and Sb) and p type (Ga and In) dopants in Si with excess vacancy concentration were analyzed. The vacancies were formed by high dose ion implantation of oxygen or nitrogen at high temperature, following previously studied procedures. Dopants were implanted to a dose of 5x1014 cm-2 at 20 keV in the vacancy rich regions of the samples. Identical doping implantations were performed in bulk Si and SIMOX. Samples were then submitted to thermal annealing at 1000ºC for 10 s or 15 min. The dopants atomic profiles were obtained by Medium Energy Ion Scattering and the active dopant profiles, by differential Hall measurements. The redistribution and the electrical properties of each dopant in bulk Si were similar to those observed in SIMOX, but several differences were observed in the vacancy-rich samples. Vacancies reduced the electrical activation of As and Sb, although the activation was maintained stable after long annealing times. The redistribution of these dopants was, otherwise, dominated by the ion used in the vacancy generation, i.e., nitrogen or oxygen. The presence of oxygen resulted in larger As retained dose, while the presence of nitrogen, in larger Sb retained dose. Regarding the p type dopants, Ga and In, the vacancies played an important role in their redistribution, reducing their out-diffusion and allowing larger retained doses. Ga and especially In electrical activation was low, where strong influence of the pre-implanted ions was observed, especially oxygen.

INTRODUCAO: A comunicação interatrial tipo \"ostium secundum\" é um defeito cardíaco congênito caracterizado pela deficiência parcial ou total da lâmina da fossa oval, também chamada de septo primo. Corresponde a 10 a 12% do total de cardiopatias congênitas, sendo a mais frequente na idade adulta. Atualmente a oclusão percutânea é o método terapêutico de escolha em defeitos com características anatômicas favoráveis para o implante de próteses na maioria dos grandes centros mundiais. A ecocardiografia transesofágica bidimensional com mapeamento de fluxo em cores é considerada a ferramenta padrão-ouro para a avaliação anatômica e monitoração durante do procedimento, sendo crucial para a ótima seleção do dispositivo. Neste sentido, um balão medidor é introduzido e insuflado através do defeito de forma a ocluí-lo temporariamente. A medida da cintura que se visualiza no balão (diâmetro estirado) é utilizada como referência para a escolha do tamanho da prótese. Recentemente a ecocardiografia tridimensional transesofágica em tempo real tem sido utilizada neste tipo de intervenção percutânea. Neste estudo avaliamos o papel da mesma na ótima seleção do dispositivo levando-se em consideração as dimensões e a geometria do defeito e a espessura das bordas do septo interatrial. METODO: Estudo observacional, prospectivo, não randomizado, de único braço, de uma coorte de 33 pacientes adultos portadores de comunicação interatrial submetidos a fechamento percutâneo utilizando dispositivo de nitinol autocentrável (Cera ®, Lifetech Scientific, Shenzhen, China). Foram analisadas as medidas do maior e menor diâmetro do defeito, sua área e as medidas do diâmetro estirado com balão medidor obtidas por meio das duas modalidades ecocardiográficas. Os defeitos foram considerados como elípticos ou circulares segundo a sua geometria; as bordas ao redor da comunicação foram consideradas espessas (>2 mm) ou finas. O dispositivo selecionado foi igual ou ate 2 mm maior que o diâmetro estirado na ecocardiografia transesofágica bidimensional (padrão-ouro). Na tentativa de identificar uma variável que pudesse substituir o diâmetro estirado do balão para a ótima escolha do dispositivo uma série de correlações lineares foram realizadas. RESULTADOS: A idade e peso médio foram de 42,1 ± 14,9 anos e 66,0 ± 9,4kg, respectivamente; sendo 22 de sexo feminino. Não houve diferenças estatísticas entre os diâmetros maior e menor ou no diâmetro estirado dos defeitos determinados por ambas as modalidades ecocardiográficas. A correlação entre as medidas obtidas com ambos os métodos foi ótima (r > 0,90). O maior diâmetro do defeito, obtido à ecoardiografia transesofágica tridimensional, foi a variável com melhor correlação com o tamanho do dispositivo selecionado no grupo como um todo (r= 0,89) e, especialmente, nos subgrupos com geometria elíptica (r= 0,96) e com bordas espessas ao redor do defeito (r= 0,96). CONCLUSÃO: Neste estudo em adultos com comunicações interatriais tipo ostium secundum submetidos à oclusão percutânea com a prótese Cera ®, a ótima seleção do dispositivo pôde ser realizada utilizando-se apenas a maior medida do defeito obtida na ecocardiografia transesofágica tridimensional em tempo real, especialmente nos pacientes com defeitos elípticos e com bordas espessas. / INTRODUCTION: The ostium secundum atrial septal defect is a congenital heart disease characterized by partial or total deficiency of the fossa ovalis, also known as the septum primum. It corresponds to 10-12% of all congenital heart defects, being the most frequently found in adulthood. Currently, percutaneous closure is the therapeutic method of choice for defects with suitable anatomic features for device implantation in most centers in the world. Bi-dimensional transesophageal echocardiography with color flow mapping is considered the gold-standard tool for anatomic assessment and procedural monitoring, being crucial for optimal device selection. In this regard, a sizing balloon is introduced and inflated across the defect with temporary occlusion. The waist measurement seen on the balloon (stretched diameter) is used as a reference for selection of device size. Recently, real time three-dimensional transesophageal echocardiography has been utilized in this type of percutaneous intervention. In this study we assessed the role of this modality in optimal device selection taking into consideration the dimensions and the geometry of the defect and the thickness of the interatrial septum rims. METHODS: Observational, prospective, non-randomized, single-arm study of a cohort of 33 adults with atrial septal defects submitted to percutaneous closure using a self-centered nitinol device (Cera (TM), Lifetech Scientific, Shenzhen, China). The largest and the smallest diameter of the defect, its area and the measurements of the stretched diameter of the sizing balloon were assessed by both echocardiographic modalities. The defects were considered as elliptical or circular according to their geometry; the rims surrounding the defect were considered thick (> 2 mm) or thin. The selected device was equal to or 2 mm larger than the stretched diameter on bi-dimensional transesophageal echocardiography (gold-standard). In an attempt to identify a variable that could replace the stretched balloon diameter, a series of linear correlations were performed. RESULTS: The mean age and weight were 42.1 ± 14.9 years and 66.0 ± 9.4 kgs, respectively; being 22 of the female gender. There were no statistical differences between the largest and smallest diameters of the defects and the stretched diameters determined by both echocardiographic modalities. The correlation between the measurements obtained by both methods was excellent (r > 0.90). The largest defect diameter obtained by three-dimensional transesophageal echocardiography was the variable that showed the best correlation with the selected device size in the entire group (r= 0.89), especially in the subgroups with elliptical geometry (r= 0.96) and with thick rims surrounding the defect (r=0.96). CONCLUSIONS: In this study in adults with ostium secundum atrial septal defects submitted to percutaneous occlusion with the Cera (TM) device, optimal device selection could be performed using solely the largest diameter of the defect obtained by real time three-dimensional transesophageal echocardiography, especially in patients with elliptical defects and thick rims.

In recent years there has been a growing demand to produce lightweight high pressure die cast (HPDC) parts for structural applications to decrease vehicle mass and to reduce manufacturing costs. Due to the coupled rapid heat flow and complex flow/deformation that occur in the process, the formation of microstructure and defects in HPDC are still not fully understood. Developing a better understanding of microstructure formation is essential to enable advances in die design and process optimisation, as well as alloy development, to improve the quality and productivity of HPDC components. Therefore, this thesis aims to enhance this understanding by conducting detailed microstructural analysis of samples produced in controlled HPDC experiments. In the first series of experiments, various microstructure characterisation techniques were used to study salient HPDC microstructural features. The microstructures of castings were characterised at different length scales, from the scale of the casting to the scale of the eutectic interlamellar spacing. The results show that the salient as-cast microstructural features, e.g. externally solidified crystals (ESCs), defect bands, surface layer, grain size distribution, porosity and hot tears were similar for both two HPDC-specific Al alloys used, AlSi4MgMn and AlMg5Si2Mn. The formation of these features has been explained by considering the influence of flow and solidification during each stage of the HPDC process. The formation of defect bands is further studied by investigating the ratio between band thickness ( ) and average grain size in the band ( ). Suitable methods for measuring w and dsb in HPDC have been developed. The w/dsb relationship of defect bands has been investigated in HPDC specimens from a range of alloys, casting geometries and band locations within castings. The bands were measured to be 7-18 mean grains wide. This is substantial evidence that defect bands form due to strain localisation in partially solidified alloys during cold-chamber and hot-chamber HPDC. At the end of solidification, dilatant shear bands contain a higher eutectic volume fraction and/or porosity content than adjacent material. In the cross-section of the AM50 Mg alloy, the centrally-located band contains a much higher volume fraction of concentrated porosity than the second-outermost band and insignificant porosity was found in the outermost band. The level of porosity in bands was attributed to the relative difficulty of feeding shrinkage for each band location. As the feeding of material during the intensification stage is important for the reduction of porosity, the influence of intensification pressure (IP) and gate thickness on the transport of material through the gate during the latter stages of HPDC were investigated. Microstructural characterisation of the gate region indicated a marked change in feeding mechanism with increasing IP and gate size. Castings produced with a high IP and/or thick gate contained a relatively low fraction of total porosity and shear band-like features existed through the gate, suggesting that semi-solid strain localisation in the gate is involved in feeding during the pressure intensification stage. When a low IP is combined with a thin gate, no shear band was observed in the gate and feeding was less effective, resulting in a higher level of porosity in the HPDC component. As equiaxed primary crystals are subjected to intense shear during HPDC, their agglomeration and bending behaviour were investigated in the last series of experiment. Samples produced by near-static cooling, HPDC and Thixomoulding®, where the solidifying crystals experience different levels of mechanical stresses, were characterised. The electron backscatter diffraction (EBSD) technique was used to acquire grain misorientation data which is linked to the crystal agglomeration and bending behaviour during solidification. The number fraction of low-energy grain boundaries in HPDC and Thixomoulded samples was substantially higher than in ‘statically cooled’ samples. This is attributed to the much higher shear stresses and pressure applied on the solidifying alloy in HPDC and Thixomoulding, which promote crystal collisions and agglomeration. In-grain misorientations were found to be significant only in branched dendritic crystals which were subjected to significant shear stresses. This is related to the increased bending moment acting on long protruding dendrite arms compared to more compact crystal morphologies.