Orientador: Luiz Eduardo Gomes Garcia Betting / Resumo: Fundamento: Evidências experimentais de modelos animais de crises de ausência sugerem focalidades no início das descargas generalizadas. Estudos clínicos indicam que pacientes com o diagnóstico de epilepsia generalizada idiopática (EGI) exibem anormalidades focais que envolvem o circuito tálamo-cortical no eletroencefalograma (EEG) e na neuroimagem. Objetivos: Investigar a presença de características focais nas descargas generalizadas interictais usando análise quantitativa do EEG (EEGq) e avaliar o córtex do giro do cíngulo usando múltiplas abordagens quantitativas de neuroimagem. Métodos: 75 EEGs de 64 pacientes foram analisados. A primeira espícula generalizada inequívoca foi marcada para cada descarga. Três métodos de análise de fonte geradora da atividade observada foram aplicados: transformação do dipolo em imagem (dipole source imaging-DSI), abordagem LORETA aplicada iterativamente (CLARA), e análise de dipolo equivalente de componentes independentes com análise de agrupamentos. Após processamento do EEG, 32 pacientes (18 mulheres, 32 ± 11) fizeram ressonância magnética. Foram utilizados três métodos para comparar o giro do cíngulo de pacientes e controles: morfometria baseada em voxel (VBM), análise cortical e análise de formato. Resultados: 753 descargas generalizadas foram analisadas. Usando as três técnicas, o lobo frontal foi a principal fonte das descargas (70%), seguido pelos lobos parietal e occipital (14%) e, por fim, os núcleos da base (12%... (Resumo completo, clicar acesso eletrônico abaixo) / Abstract: Background: Experimental evidence from animal models of absence seizures suggests a focal source for the initiation of generalized spike-and-wave (GSW) discharges. Clinical studies indicate that patients diagnosed with idiopathic generalized epilepsy (IGE) exhibit focal electroencephalographic and subtle structural abnormalities, which involve the thalamo-cortical circuitry. Aims: The objectives of the current investigation were to investigate whether interictal generalized discharges exhibit focal characteristics using qEEG analysis and to perform a comprehensive analysis of the cingulate cortex using multiple quantitative structural neuroimaging techniques. Methods: 75 EEG recordings from 64 patients were analyzed. The first unequivocally confirmed generalized spike was marked for each discharge. Three methods of source imaging analysis were applied: dipole source imaging (DSI), classical LORETA analysis recursively applied (CLARA), and equivalent dipole of independent components with cluster analysis. After EEG analysis, 32 patients (18 women, 30± 10 years) and 36 controls (18 women, 32 ±11 years) were imaged by 3 Tesla magnetic resonance (MRI). We used three models to compare cingulate gyrus of patients and the control group: voxel-based morphometry (VBM), cortical analyses and shape analyses. Results: A total of 753 GSW discharges were spatiotemporally analyzed. Source analysis using all three techniques revealed that the frontal lobe was the principal ... (Complete abstract click electronic access below) / Doutor

L’apparition de la segmentation électrique des détecteurs au GeHP et de l’électronique numérique a ouvert la voie à des applications prometteuses, telles que le tracking γ, l’imagerie γ ou la mesure bas bruit de fond, pour lesquelles une connaissance fine de la réponse du détecteur est un atout. L’IPHC a développé une table de scan utilisant un faisceau collimaté, qui sonde la réponse d’un détecteur dans tout son volume en fonction de la localisation de l’interaction. Elle est conçue pour utiliser une technique innovante de scan 3D, le Pulse Shape Comparison Scan, qui a été d’abord simulée afin de démontrer son efficacité. Un détecteur AGATA a été scanné de manière approfondie. Des scan 2D classiques ont permis, entre autres, de mettre en évidence des effets locaux de modification de la collection des charges, liés à la segmentation. Pour la première fois, une base de données 3D, complète, de formes d’impulsions fonction de la position d’interaction a été établie. Elle permettra notamment d’améliorer les performances du spectromètre AGATA. / Recent developments of electrical segmentation of HPGe detectors, coupled with digital electronics have led to promising applications such as γ-ray tracking, γ-ray imaging or low-background measurements which will benefit from a fine knowledge of the detector response. The IPHC has developed a new scanning table which uses a collimated γ-ray beam to investigate the detector response as a function of the location of the γ-ray interaction. It is designed to use the Pulse Shape Comparison Scan technique, which has been simulated in order to prove its efficiency. An AGATA detector has been thoroughly scanned. 2D classical scans brought out, for example, local charge collection modification effects such as charge sharing, due to the segmentation. For the first time, a 3D, complete pulse-shape database has been established. It will especially allow to improve the overall AGATA array performances.

L’objectif de cette thèse est l’étude des changements de la forme de l’hippocampe due à l’atrophie causée par la maladie d’Alzheimer. Pour ce faire, des algorithmes et des méthodes ont été développés pour segmenter l’hippocampe à partir d’imagerie structurelle par résonance magnétique (IRM) et pour modéliser les variations dans sa forme. Nous avons utilisé une méthode de segmentation par propagation de multiple atlas pour la segmentation de l’hippocampe, méthode qui a été démontrée comme étant robuste dans la segmentation des structures cérébrales. Nous avons développé une méthode supervisée pour construire une base de données d’atlas spécifique à la population d’intérêt en propageant les parcellations d’une base de données génériques d’atlas. Les images correctement segmentées sont inspectées et ajoutées à la base de données d’atlas, de manière à améliorer sa capacité à segmenter de nouvelles images. Ces atlas sont évalués en termes de leur accord lors de la segmentation de nouvelles images. Comparé aux atlas génériques, les atlas spécifiques à la population d’intérêt obtiennent une plus grande concordance lors de la segmentation des des images provenant de cette population. La sélection d’atlas est utilisée pour améliorer la précision de la segmentation. La méthode classique de sélection basée sur la similarité des images est ici étendue pour prendre en compte la pertinence marginale maximale (MMR) et la régression des moindres angles (LAR). En prenant en considération la redondance parmi les atlas, des critères de diversité se montrent être plus efficace dans la sélection des atlas dans le cas où seul un nombre limité d’atlas peut-être fusionné. A partir des hippocampes segmentés, des modèles statistiques de la forme (SSM) sont construits afin de modéliser les variations de la forme de l’hippocampe dans la population. La correspondance entre les hippocampes est établie par une optimisation d’ensemble des surfaces paramétriques. Les paramétrages sphériques des surfaces sont aplatis pour faciliter la reparamétrisation et l’interpolation. Le reparamétrage est régularisé par une contrainte de type fluide visqueux, qui est effectué à l’aide d’une implémentation basée sur la transformées en sinus discrète. Afin d’utiliser le SSM pour décrire la forme d’une nouvelle surface hippocampique, nous avons développé un estimateur des paramètres du model de la forme basée sur l’espérance-maximisation de l’algorithme du plus proche voisin itéré (EM-ICP). Un terme de symétrie est inclus pour forcer une consistance entre la transformée directe et inverse entre le modèle et la forme, ce qui permet une reconstruction plus précise de la forme à partir du modèle. La connaissance a priori sur la forme modélisé par le SSM est utilisée dans l’estimation du maximum a posteriori des paramètres de forme. Cette méthode permet de forcer la continuité spatiale et éviter l’effet de sur-apprentissage. Dans l’étude de l’hippocampe dans la maladie d’Alzheimer, nous utilisons le SSM pour modéliser le changement de forme de l’hippocampe entre les sujets sains et des patients souffrant d’Alzheimer. Nous identifions les régions touchées par l’atrophie dans la maladie d’Alzheimer en évaluant la différence entre les groupes de contrôle et ceux d’Alzheimer sur chaque point correspondant sur la surface. L’analyse des changements de la forme est restreinte aux régions présentant des différences significatives entre les groupes, ce qui a pour effet d’améliorer la discrimination basée sur l’analyse en composantes principales (ACP) du SSM. Les composantes principales décrivant la variabilité de la forme à l’intérieur des régions discriminantes ont une corrélation plus fortes avec le déclin des scores de mémoire épisodique liée à la pathologie de l’hippocampe dans la maladie d’Alzheimer. / The aim of this thesis is to investigate the shape change in hippocampus due to the atrophy in Alzheimer’s disease (AD). To this end, specific algorithms and methodologies were developed to segment the hippocampus from structural magnetic resonance (MR) images and model variations in its shape. We use a multi-atlas based segmentation propagation approach for the segmentation of hippocampus which has been shown to obtain accurate parcellation of brain structures. We developed a supervised method to build a population specific atlas database, by propagating the parcellations from a smaller generic atlas database. Well segmented images are inspected and added to the set of atlases, such that the segmentation capability of the atlas set may be enhanced. The population specific atlases are evaluated in terms of the agreement among the propagated labels when segmenting new cases. Compared with using generic atlases, the population specific atlases obtain a higher agreement when dealing with images from the target population. Atlas selection is used to improve segmentation accuracy. In addition to the conventional selection by image similarity ranking, atlas selection based on maximum marginal relevance (MMR) re-ranking and least angle regression (LAR) sequence are developed for atlas selection. By taking the redundancy among atlases into consideration, diversity criteria are shown to be more efficient in atlas selection which is applicable in the situation where the number of atlases to be fused is limited by the computational resources. Given the segmented hippocampal volumes, statistical shape models (SSMs) of hippocampi are built on the samples to model the shape variation among the population. The correspondence across the training samples of hippocampi is established by a groupwise optimization of the parameterized shape surfaces. The spherical parameterization of the hippocampal surfaces are flatten to facilitate the reparameterization and interpolation. The reparameterization is regularized by viscous fluid, which is solved by a fast implementation based on discrete sine transform. In order to use the hippocampal SSM to describe the shape of an unseen hippocampal surface, we developed a shape parameter estimator based on the expectationmaximization iterative closest points (EM-ICP) algorithm. A symmetric data term is included to achieve the inverse consistency of the transformation between the model and the shape, which gives more accurate reconstruction of the shape from the model. The shape prior modeled by the SSM is used in the maximum a posteriori estimation of the shape parameters, which is shown to enforce the smoothness and avoid the effect of over-fitting. In the study of the hippocampus in AD, we use the SSM to model the hippocampal shape change between the healthy control subjects and patients diagnosed with AD. We identify the regions affected by the atrophy in AD by assessing the spatial difference between the control and AD groups at each corresponding landmark. Localized shape analysis is performed on the regions exhibiting significant inter-group difference, which is shown to improve the discrimination ability of the principal component analysis (PCA) based SSM. The principal components describing the localized shape variability among the population are also shown to display stronger correlation with the decline of episodic memory scores linked to the pathology of hippocampus in AD.

Neste trabalho são apresentados dois novos descritores de forma para tarefas de recuperação de imagens por conteúdo (CBIR) e análise de formas, que são construídos sobre uma extensão do conceito de tensor scale baseada na Transformada de Distância Euclidiana (EDT). Primeiro, o algoritmo de tensor scale é utilizado para extrair informações da forma sobre suas estruturas locais (espessura, orientação e anisotropia) representadas pela maior elipse contida em uma região homogênea centrada em cada pixel da imagem. Nos novos descritores, o limite do intervalo das orientações das elipses do modelo de tensor scale é estendido de 180º para 360º, de forma a melhor discriminar a descrição das estruturas locais. Então, com base em diferentes abordagens de amostragem, visando resumir informações mais relevantes, os novos descritores são construídos. No primeiro descritor proposto, Tensor Scale Sector (TSS), a distribuição das orientações relativas das estruturas locais em setores circulares é utilizada para compor um vetor de características de tamanho fixo, para uma caracterização de formas baseada em região. No segundo descritor, o Tensor Scale Band (TSB), foram considerados histogramas das orientações relativas extraídos de bandas concêntricas, formando também um vetor de características de tamanho fixo, com uma função de distância de tempo linear. Resultados experimentais com diferentes bases de formas (MPEG-7 e MNIST) são apresentados para ilustrar e validar os métodos. TSS demonstra resultados comparáveis aos métodos estado da arte, que geralmente dependem de algoritmos custosos de otimização de correspondências. Já o TSB, com sua função de distância em tempo linear, se demonstra como uma solução adequada para grandes coleções de formas. / In this work, two new shape descriptors are proposed for tasks in Content-Based Image Retrieval (CBIR) and Shape Analysis tasks, which are built upon an extended tensor scale based on the Euclidean Distance Transform (EDT). First, the tensor scale algorithm is applied to extract shape attributes from its local structures (thickness, orientation, and anisotropy) as represented by the largest ellipse within a homogeneous region centered at each image pixel. In the new descriptors, the upper limit of the interval of local orientation of tensor scale ellipses is extended from 180º to 360º, to better discriminate the description of local structures. Then, the new descriptors are built based on different sampling approaches, aiming to summarize the most relevant features. In the first proposed descriptor, Tensor Scale Sector descriptor (TSS), the local distributions of relative orientations within circular sectors are used to compose a fixed-length feature vector, for a region-based shape characterization. For the second method, the Tensor Scale Band (TSB) descriptor, histograms of relative orientations are considered for each circular concentric band, to also compose a fixed-length feature vector, with linear time distance function for matching. Experimental results for different shape datasets (MPEG-7 and MNIST) are presented to illustrate and validate the methods. TSS can achieve high retrieval values comparable to state-of-the-art methods, which usually rely on time-consuming correspondence optimization algorithms, but uses a simpler and faster distance function, while the even faster linear complexity of TSB leads to a suitable solution for very large shape collections.

Les différentes étapes et processus de la fabrication additive (FA) induisent des erreurs de sources multiples et complexes qui soulèvent des problèmes majeurs au niveau de la qualité géométrique du produit fabriqué. Par conséquent, une modélisation effective des écarts géométriques est essentielle pour la FA. Le paradigme Skin Model Shapes (SMS) offre un cadre intégral pour la modélisation des écarts géométriques des produits manufacturés et constitue ainsi une solution efficace pour la modélisation des écarts géométriques en FA.Dans cette thèse, compte tenu de la spécificité de fabrication par couche en FA, un nouveau cadre de modélisation à base de SMS est proposé pour caractériser les écarts géométriques en FA en combinant une approche dans le plan et une approche hors plan. La modélisation des écarts dans le plan vise à capturer la variabilité de la forme 2D de chaque couche. Une méthode de transformation des formes est proposée et qui consiste à représenter les effets de variations sous la forme de transformations affines appliquées à la forme nominale. Un modèle paramétrique des écarts est alors établi dans un système de coordonnées polaires, quelle que soit la complexité de la forme. Ce modèle est par la suite enrichi par un apprentissage statistique permettant la collecte simultanée de données des écarts de formes multiples et l'amélioration des performances de la méthode.La modélisation des écarts hors plan est réalisée par la déformation de la couche dans la direction de fabrication. La modélisation des écarts hors plan est effectuée à l'aide d'une méthode orientée données. Sur la base des données des écarts obtenues à partir de simulations par éléments finis, deux méthodes d'analyse modale: la transformée en cosinus discrète (DCT) et l'analyse statistique des formes (SSA) sont exploitées. De plus, les effets des paramètres des pièces et des procédés sur les modes identifiés sont caractérisés par le biais d'un modèle à base de processus Gaussien.Les méthodes présentées sont finalement utilisées pour obtenir des SMSs haute-fidélité pour la fabrication additive en déformant les contours de la couche nominale avec les écarts prédits et en reconstruisant le modèle de surface non idéale complet à partir de ces contours déformés. Une toolbox est développée dans l'environnement MATLAB pour démontrer l'efficacité des méthodes proposées. / The intricate error sources within different stages of the Additive Manufacturing (AM) process have brought about major issues regarding the dimensional and geometrical accuracy of the manufactured product. Therefore, effective modeling of the geometric deviations is critical for AM. The Skin Model Shapes (SMS) paradigm offers a comprehensive framework aiming at addressing the deviation modeling problem at different stages of product lifecycle, and is thus a promising solution for deviation modeling in AM. In this thesis, considering the layer-wise characteristic of AM, a new SMS framework is proposed which characterizes the deviations in AM with in-plane and out-of-plane perspectives. The modeling of in-plane deviation aims at capturing the variability of the 2D shape of each layer. A shape transformation perspective is proposed which maps the variational effects of deviation sources into affine transformations of the nominal shape. With this assumption, a parametric deviation model is established based on the Polar Coordinate System which manages to capture deviation patterns regardless of the shape complexity. This model is further enhanced with a statistical learning capability to simultaneously learn from deviation data of multiple shapes and improve the performance on all shapes.Out-of-plane deviation is defined as the deformation of layer in the build direction. A layer-level investigation of out-of-plane deviation is conducted with a data-driven method. Based on the deviation data collected from a number of Finite Element simulations, two modal analysis methods, Discrete Cosine Transform (DCT) and Statistical Shape Analysis (SSA), are adopted to identify the most significant deviation modes in the layer-wise data. The effect of part and process parameters on the identified modes is further characterized with a Gaussian Process (GP) model. The discussed methods are finally used to obtain high-fidelity SMSs of AM products by deforming the nominal layer contours with predicted deviations and rebuilding the complete non-ideal surface model from the deformed contours. A toolbox is developed in the MATLAB environment to demonstrate the effectiveness of the proposed methods.

This thesis deals with image analysis methods which can be exploited in exoscopic analysis of sedimentary grains, specifically for the purpose of distinguishing between geomorphologic geneses which influenced a form of sedimentary grains. The images of sedimentary grains were acquired by a scanning electron microscope. The main contribution is the proposal of multiple methods that can significantly automate the exoscopic analysis. These methods cover the automatic segmentation of grains in image, the automatic analysis of roundness of 2D grain projection and the classification of geomorphologic geneses according to the grain surface structure. In the section concerning the automatic segmentation, a segmentation method enabling an easy subsequent manual result correction was proposed. This method is based on the split-and-merge approach. The individual steps the procedure were designed to exploit specific properties of sedimentary grain images in order to obtain the best segmentation results. In the section concerning the automatic roundness analysis of 2D projection of sedimentary grains, an influence of pixel resolution on a result roundness value was evaluated. Further, a minimal number of grains, which is necessary to analyze in order to reliably compare a pair of geomorphological geneses, was investigated. For the determination of this number, a method was proposed and experimentally verified. In the section of automatic analysis of sedimentary grain surface structure, a method for classification of geomorphologic geneses was proposed. The method utilizes low-level texture features which describes individual images of sedimentary grains. A model of geomorphological genesis is constituted of a set of histograms representing occurrences of different configurations of low-level texture features. The methods proposed in the thesis were tested and evaluated based on a database, which consists of sedimentary grain samples from 4 different geomorphological geneses (eolic, glacial, slope and volcanic).

This paper describes how feature extraction on ancient pottery can be combined with recent developments in artificial intelligence to draw up an automated, but still flexible classification system. These features include for instance several dimensions of the vessel's body, ratios thereof, an abstract representation of the overall shape, the shape of vessel segments and the number and type of attachments such as handles, lugs and feet. While most traditional approaches to classification are based on statistical analysis or the search for fuzzy clusters in high-dimensional spaces, we apply machine learning techniques, such as decision tree algorithms and neural networks. These methods allow for an objective and reproducible classification process. Conclusions about the "typability" of data, the evolution of types and the diagnostic attributes of the types themselves can be drawn as well.

CdZnTe-Detektoren, zur direkten Messung von Gammastrahlung, die bei der Behandlung mit beschleunigten Teilchen entsteht, besitzen das Potential eine Reichweitenkontrolle zu ermöglichen und die Strahlendosis zu erfassen. Jedoch stellt die Identifizierung einzelner, energetisch nahe beieinander liegenden Photonenenergien, bei einem solchen Volumendetektor eine besondere Herausforderung dar. Die vorliegende Arbeit beschäftigt sich mit der Entwicklung von Methoden zur Korrektur der Signalformen am Volumenhalbleiter CdZnTe und der damit verbundenen Verbesserung der Energie- und Zeitinformation des Detektors. Dies ist wichtig für den Einsatz in der therapeutischen Medizin mit beschleunigten Teilchen, da Ladungsträger durch Gammastrahlung in unterschiedlichen Tiefen des Detektors generiert werden und einen tiefenabhängigen Fehler in der Detektorgenauigkeit erzeugen. / CdZnTe detectors, used for the direct measurement of gamma radiation generated during the treatment with accelerated particles, have the potential to provide a range control and to detect the radiation dose. However, the identification of individual energetically close photon energies in such a volume detector is a particular challenge. The present work deals with the development of methods for correcting the signal forms of the CdZnTe and the associated improvement of the energy and time information of the detector This is important for use in accelerated particle medicine because charge carriers are generated by gamma radiation at different depths of the detector and produce a depth dependent error in detector accuracy.

No description available.

Den större ischiasskåran (incisura ischiadica major) är en inskärning i höftbenet som karakteriseras av morfologier, användbara för att estimera biologiskt kön. Slutsatser gjorda från okulära observationer kan variera beroende på utövare och därmed kan morfologiska metoder anses vara mindre tillförlitliga gentemot metriska metoder. Tillvägagångssättet för denna uppsats bestod av en jämförande studie mellan en metod som använder formanalys och en som använder vinkelgrad för att bedöma biologiskt kön, på den större ischiasskåran. I denna uppsats användes ett praktiskt tillvägagångssätt för att observera 33 höftben från Sankt Hans medeltida kyrkogård. Det osteologiska materialet var inlånat från Gotlands museum och det praktiska arbetet utfördes på plats på magasinet, under våren 2024. Undersökningsmaterialet avgränsades till att inkludera endast vuxna individer av både manligt och kvinnligt kön. Resultaten visade att det finns en korrelation mellan kurvan på inskärningen och biologiskt kön. I diskussionsdelen av uppsatsen diskuterades tillförlitlighet och användarvänlighet för de två metoderna samt hur de kan nyttjas i osteologiska sammanhang. / The greater sciatic notch (incisura ischiadica major) is an incision in the hip bone that is characterized by morphologies, useful to assess biological sex. Conclusions that are made from visual observations may vary between practitioners, and therefore, morphological methods can be less reliable than metric methods. The approach of this essay consisted of a comparative study between a method using shape analysis and one using angle degree to assess biological sex, on the greater sciatic notch. In this essay, a practical approach was applied to observe 33 hip bones from Sankt Hans medieval cemetery. The material was borrowed from Gotland’s Museum, and the practical work was performed on site, during spring of 2024. The studied material was delimitated to include only adult individuals consisting of both males and females. The results showed that there is a correlation between the curve of the incision and biological sex. In the discussion, the essay explored the reliability and user-friendliness of the two methods, along with their potential applications in osteological contexts.