Different medical imaging modalities provide complementary anatomical and functional information. One increasingly important use of such information is in the clinical management of cardiovascular disease. Multi-modality data is helping improve diagnosis accuracy, and individualize treatment. The Clinical Research Imaging Centre at the University of Edinburgh, has been involved in a number of cardiovascular clinical trials using longitudinal computed tomography (CT) and multi-parametric magnetic resonance (MR) imaging. The critical image processing technique that combines the information from all these different datasets is known as image registration, which is the topic of this thesis. Image registration, especially multi-modality and multi-parametric registration, remains a challenging field in medical image analysis. The new registration methods described in this work were all developed in response to genuine challenges in on-going clinical studies. These methods have been evaluated using data from these studies. In order to gain an insight into the building blocks of image registration methods, the thesis begins with a comprehensive literature review of state-of-the-art algorithms. This is followed by a description of the first registration method I developed to help track inflammation in aortic abdominal aneurysms. It registers multi-modality and multi-parametric images, with new contrast agents. The registration framework uses a semi-automatically generated region of interest around the aorta. The aorta is aligned based on a combination of the centres of the regions of interest and intensity matching. The method achieved sub-voxel accuracy. The second clinical study involved cardiac data. The first framework failed to register many of these datasets, because the cardiac data suffers from a common artefact of magnetic resonance images, namely intensity inhomogeneity. Thus I developed a new preprocessing technique that is able to correct the artefacts in the functional data using data from the anatomical scans. The registration framework, with this preprocessing step and new particle swarm optimizer, achieved significantly improved registration results on the cardiac data, and was validated quantitatively using neuro images from a clinical study of neonates. Although on average the new framework achieved accurate results, when processing data corrupted by severe artefacts and noise, premature convergence of the optimizer is still a common problem. To overcome this, I invented a new optimization method, that achieves more robust convergence by encoding prior knowledge of registration. The registration results from this new registration-oriented optimizer are more accurate than other general-purpose particle swarm optimization methods commonly applied to registration problems. In summary, this thesis describes a series of novel developments to an image registration framework, aimed to improve accuracy, robustness and speed. The resulting registration framework was applied to, and validated by, different types of images taken from several ongoing clinical trials. In the future, this framework could be extended to include more diverse transformation models, aided by new machine learning techniques. It may also be applied to the registration of other types and modalities of imaging data.

Cette thèse étudie les mécanismes de sélection de l'action et de choix de stratégie tels qu'ils apparaissent à travers des expériences animales et des enregistrements neurobiologiques. Nous proposons ensuite des modèles biologiquement plausibles de la sélection de l'action. L'objectif est de mieux comprendre le fonctionnement du cerveau chez les êtres vivants et de pouvoir endéduire des architectures de contrôle bio-inspirées, plus robustes et adaptées à l'environnement. Les modèles étudiés sont réalisés avec des réseaux de neurones artificiels, permettant de modéliser des régions cérébrales et ainsi pouvoir simuler le fonctionnement du cerveau, ce qui permet de tester nos hypothèses sur des robots et des agents virtuels.L'étude de la sélection de l'action pour des robots mobiles implique plusieurs approches. La sélection de l'action peut être étudiée du point de vue du choix entre plusieurs actions basiques, e.g. un choix binaire aller à gauche ou à droite. Ceci passe forcément par l'acquisition et la catégorisation d'instants et d'événements spéciaux, perçus ou effectués, qui représentent des contextes dans lesquels la perception change, le comportement est modifié ou bien la sélection est réalisée. Ainsi, la thèse traite aussi de l'acquisition, la catégorisation et l'encodage de ces événements importants dans la sélection del'action.Enfin, on s'intéressera à la sélection de l'action du point de vue de la sélection de stratégie. Les différents comportements peuvent être dirigés consciemment ou bien être des automatismes acquis avec l'habitude. Le but ici est d'explorer différentes approches pour que le robot puisse développer ces deux capacités, mais aussi d'étudier les interactions entre ces types de mécanismes dans la cadre de tâches de navigation.Les travaux de cette thèse se basent sur la modélisation du fonctionnement de différentes boucles hippocampo-cortico-basales impliquées dans des tâches de navigation, de sélection de l'action et de catégorisations multimodales. En particulier, nous avons un modèle de l'hippocampe permettant d'apprendre des associations spatio-temporelles et des conditionnements multimodaux entre des événements perceptifs. Il se base sur des associations sensorimotrices entre des cellules appelées cellules de lieu qui sont associées avec des actions pour définir des comportements cohérents. Le modèle fait aussi intervenir des cellules de transition hippocampiques, permettant de faire des prédictions temporelles sur les événements futurs. Celles-ci permettent l'apprentissagede séquences spatio-temporelles, notamment du fait qu'elles représentent le substrat neuronal à l'apprentissage d'une carte cognitive, située elle au niveau du cortex préfrontal et/ou pariétal.Ce type de carte permet de planifier des chemins à suivre en fonction des motivations du robot, ce qui permet de rejoindre différents buts précédemment découverts dans l'environnement. / This thesis aims at studying the different mechanisms involved in action selection and decision making processes, according to animal experiments and neurobiological recordings. For that matter, we propose several biologically plausible models for action selection. The goal is to achieve a better understanding of the animal's brain functions. This gives us the opportunity todevelop bioinspired control architectures for robots that are more robust and adaptative to a real environement. These models are based on Artificial Neural Networks, allowing us to test our hypotheses on simulations of different brain regions and function, implemented on robots and virtual agents.Action selection for mobile robots can be approached from different angles. This process can be seen as the selection between two possibilities, e.g. go left or go right. Those mechanisms involve the ability to learn and categorize specific events, encoding contexts where a change in the perception is perceived, a change in the behavior is noticed or the decision is made. There-fore, this thesis studies those capacities of acquisition, categorisation and coding of different events that can be relevant for action selection.We also, approach the action selection as a strategy selection. The different behaviors are guided consciously or through automated behavior learned as habits. We investigate different possibilities allowing a robot to develop those capacities. Also, we aim at studying interactions that can emerge between those mechanisms during navigational behaviors.The work presented in this these is based on the modelisation of the hippocampo-cotico-basal loops involved in the navigational behaviors, the action selection and the multimodal categorisation of events. We base our models on a previous model of the hippocampus for the learning of spatio-temporal associations and for multimodal conditionning of perceptive events. It is based on sensorimotor associations between place cells and actions to achieve navigational behaviors. The model involves also a specific type of hippocampic cells, named transition cells, for temporal prediction of future events. This capacity allows the model to learn spatio-temporal sequences, and it represents the neural substrate for the learning of a cognitive map, hypothesised to be localized in prefrontal and/or parietal areas. This kind of topological map allows to plan the behavior of the robot according to its motivations, which is used in goal orientedexperiments to achieve goals and capture rewards.

There is a requirement for English teachers in Sweden to adapt their teaching to align with the policy documents advocating to foster the students' continuous and lifelong learning. This study aims to address in what way the participating teachers work to create engaging learning environments and lessons that promote communication and cooperation. Furthermore, the study explores which methods the participating teachers use to differentiate instructions and make adaptations to teacher practices and materials to successfully reach each individual student. The data was gathered by conducting qualitative semi-structured interviews with four 7-9 English teachers. The interviews were focused on four main themes: (1) Adaptations for differentiated learning through multi-modality, (2) Adaptations for differentiated learning through the bi-lingual approach, (3) Adaptations for differentiated learning through cooperative learning and (4) Adaptations for differentiated learning through other practices. Based on the guidelines provided by The Swedish National Agency for Education, findings from previous research, and the data collected in this study, it becomes evident that teachers must adopt their teaching in various ways. The adaptation of teaching strategies and practices include ways to effectively engage all of their individual groups of students, as well as the utilization of visual aids, bi-lingual instructional practices, comprehensible input and output, and cooperative learning methods. The results show that these are important ways to differentiate instruction and enhance learning to support the students’ academic and cognitive growth. The presented teacher practices can aid teachers to use differentiated instruction in accordance with the needs of their individual groups of students, both in terms of classes and the individual students within those classes.

No description available.

No description available.

Au cours des dernières décennies, la présence des auralisations dans l’acoustique architecturale et la réalité virtuelle est devenue de plus en plus importante. De nombreuses applications en découlent, telles que les explorations de la réalité virtuelle multimodale ou les études de l’influence acoustique des rénovations et la recherche historique. Malgré ces nombreux cas d’utilisation, peu d’études scientifiques ont été réalisées sur le sujet. L’objectif de cette thèse était donc d’examiner l’utilisation d’auralisations acoustiques de salles, basées sur l’acoustique géométrique (GA) comme outil scientifique et visant à aider à la création d’auralisations historiquement exactes plus écologiquement valables. Déjà dans les années 1930 les premières tentatives ont été entreprises pour rendre audible (de manière imaginaire) les champs sonores. Les développements au cours des 80 dernières années ont conduit à des améliorations significatives des auralisations. Aujourd’hui, si l’on veut créer des auralisations, l’enregistrement anéchoïque réalisé préalablement doit être convolué avec une réponse impulsionnelle ambiante, mesurée ou simulée (RIR). Les logiciels GA sont souvent utilisés pour calculer numériquement la RIR de géométries compliquées. Les méthodes basées sur les ondes sont gourmandes en calcul, nécessitant des modèles géométriques complexes et des données d’entrée complexes. Cette thèse vise à améliorer la qualité des auralisations entièrement calculées. À cette fin, on a étudié l’étalonnage des modèles acoustiques des salles et l’inclusion de la directivité vocale dynamique. Des mesures acoustiques de la pièce ont été réalisées dans quatre salles et des modèles d’acoustique géométrique ont été créés des mêmes espaces. Une procédure méthodique de calibration du modèle a été proposée, réalisée dans les quatre salles, et validée au préalable par comparaison d’estimation de paramètres. Des tests d’écoute subjectifs comparant des auralisations mesurée set simulées pour trois espaces différents ont révélé que les auralisations étaient également perçues pour huit attributs acoustiques évalués. Par la suite, un cadre permettant d’inclure la directivité vocale dynamique a été présenté. Les résultats des tests d’écoute ont montré des différences perceptuelles entre la directivité vocale dynamique et la directivité de source statique pour la plausibilité, l’enveloppement de l’auralisation ainsi que la largeur perçue de la source. L’amélioration de la validité écologique des auralisations a permis d’étudier l’influence des visualisations sur l’expérience acoustique, avec un degré de confiance raisonnable que les effets perçus sont également applicables dans des situations réelles. À cet effet, un cadre a été établi qui a permis des évaluations multimodales de pièces de théâtre et de concerts. Les résultats d’un test d’écoute multi-modal présentant une scène cohérente visuelle-sonore ont confirmé les différences perceptuelles entre les auralisations de directivité vocale dynamique et statique. Dans ce même cadre, un second test d’écoute comparant des scènes visuelles/sonores incohérentes è cohérentes, indiquait qu’avec une distance source-récepteur accrue, les auralisations sont perçues acoustiquement plus éloignées et plus élevée. / Over recent decades, auralizations have become more prevalent in architectural acoustics and virtual reality. Auralizations have numerous use-cases such as multi-modal virtual reality explorations, studies of the acoustical influence of renovations, and historic research. Despite their numerous use-cases, they rarely have been part of scientific studies. Therefore, the goal of this thesis was to examine the use of room acoustical auralizations based on geometrical acoustics (GA) as a scientific tool and aimed to aid in the creation of more ecologically valid historically accurate auralizations. Already in the 1930s first attempts were undertaken to render audible (imaginary) sound fields. Developments over the last 80 years have led to significant improvements of auralizations. Today, if one wishes to create auralizations, generally anechoic recording need to be convolved with either a measured or simulated room impulse response (RIR). GA software are often employed to numerically compute the RIR of complicated geometries. Wave-based methods are computationally intensive, requiring complex geometrical models and complex input data. This thesis aims to enhance the quality of fully computed auralizations. For this purpose the calibration of room acoustical models and the inclusion of dynamic voice directivity were studied. Room acoustical measurements were carried out in four rooms and geometrical acoustics models were created of the same spaces. A methodical calibration procedure was proposed, carried out in the four rooms, and first validated by means of parameter estimation comparison. Subjective listening tests which compared measured and simulated auralizations for three spaces found that the auralizations were equally perceived for 8 tested acoustical attributes. Subsequently, a framework was presented which enabled the inclusion of dynamic voice directivity. The results of listening tests indicated that perceptual differences between dynamic voice directivity and regular static source ordinations in plausibility and envelopment of the auralization as well as perceived width of the source. With the improved ecological validity of the auralizations it was possible to study the influence of visualizations on the acoustical experience, with a reasonable degree of confidence that perceived effects are also applicable in real-life situations. For this purpose, a framework was established which enabled multi-model assessments of theater plays and concerts. Results of a visual-aural coherent multi-modal listening test confirmed the perceptual differences between dynamic and static voice directivity auralizations. A second listening test employing this framework which compared incoherent to coherent aural-visual cues indicated that with increased visual source-receiver distance auralizations are perceived acoustically more distant and louder.

No description available.

In this dissertation we aim to perform a multi-wavelength analysis of galaxy clusters. We discuss various methods for clustering in order to determine physical parameters of galaxy clusters required for this type of study. A selection of galaxy clusters was chosen from 4 papers, (Popesso et al. 2007b, Yoon et al. 2008, Loubser et al. 2008, Brownstein & Mo at 2006) and restricted by redshift and galactic latitude to reveal a sample of 40 galaxy clusters with 0.0 < z < 0.15. Data mining using Virtual Observatory (VO) and a literature survey provided some background information about each of the galaxy clusters in our sample with respect to optical, radio and X-ray data. Using the Kayes Mixture Model (KMM) and the Gaussian Mixing Model (GMM), we determine the most likely cluster member candidates for each source in our sample. We compare the results obtained to SIMBADs method of hierarchy. We show that the GMM provides a very robust method to determine member candidates but in order to ensure that the right candidates are chosen we apply a select choice of outlier tests to our sources. We determine a method based on a combination of GMM, the QQ Plot and the Rosner test that provides a robust and consistent method for determining galaxy cluster members. Comparison between calculated physical parameters; velocity dispersion, radius, mass and temperature, and values obtained from literature show that for the majority of our galaxy clusters agree within 3 range. Inconsistencies are thought to be due to dynamically active clusters that have substructure or are undergoing mergers, making galaxy member identi cation di cult. Six correlations between di erent physical parameters in the optical and X-ray wavelength were consistent with published results. Comparing the velocity dispersion with the X-ray temperature, we found a relation of T0:43 as compared to T0:5 obtained from Bird et al. (1995). X-ray luminosity temperature and X-ray luminosity velocity dispersion relations gave the results LX T2:44 and LX 2:40 which lie within the uncertainty of results given by Rozgacheva & Kuvshinova (2010). These results all suggest that our method for determining galaxy cluster members is e cient and application to higher redshift sources can be considered. Further studies on galaxy clusters with substructure must be performed in order to improve this method. In future work, the physical parameters obtained here will be further compared to X-ray and radio properties in order to determine a link between bent radio sources and the galaxy cluster environment. / MSc (Space Physics), North-West University, Potchefstroom Campus, 2013

In this dissertation we aim to perform a multi-wavelength analysis of galaxy clusters. We discuss various methods for clustering in order to determine physical parameters of galaxy clusters required for this type of study. A selection of galaxy clusters was chosen from 4 papers, (Popesso et al. 2007b, Yoon et al. 2008, Loubser et al. 2008, Brownstein & Mo at 2006) and restricted by redshift and galactic latitude to reveal a sample of 40 galaxy clusters with 0.0 < z < 0.15. Data mining using Virtual Observatory (VO) and a literature survey provided some background information about each of the galaxy clusters in our sample with respect to optical, radio and X-ray data. Using the Kayes Mixture Model (KMM) and the Gaussian Mixing Model (GMM), we determine the most likely cluster member candidates for each source in our sample. We compare the results obtained to SIMBADs method of hierarchy. We show that the GMM provides a very robust method to determine member candidates but in order to ensure that the right candidates are chosen we apply a select choice of outlier tests to our sources. We determine a method based on a combination of GMM, the QQ Plot and the Rosner test that provides a robust and consistent method for determining galaxy cluster members. Comparison between calculated physical parameters; velocity dispersion, radius, mass and temperature, and values obtained from literature show that for the majority of our galaxy clusters agree within 3 range. Inconsistencies are thought to be due to dynamically active clusters that have substructure or are undergoing mergers, making galaxy member identi cation di cult. Six correlations between di erent physical parameters in the optical and X-ray wavelength were consistent with published results. Comparing the velocity dispersion with the X-ray temperature, we found a relation of T0:43 as compared to T0:5 obtained from Bird et al. (1995). X-ray luminosity temperature and X-ray luminosity velocity dispersion relations gave the results LX T2:44 and LX 2:40 which lie within the uncertainty of results given by Rozgacheva & Kuvshinova (2010). These results all suggest that our method for determining galaxy cluster members is e cient and application to higher redshift sources can be considered. Further studies on galaxy clusters with substructure must be performed in order to improve this method. In future work, the physical parameters obtained here will be further compared to X-ray and radio properties in order to determine a link between bent radio sources and the galaxy cluster environment. / MSc (Space Physics), North-West University, Potchefstroom Campus, 2013

Ce mémoire est consacré à la compensation des effets de flous dans une image, communément appelés effets de volume partiel (EVP), avec comme objectif d’application l’amélioration qualitative et quantitative des images en médecine nucléaire. Ces effets sont la conséquence de la faible résolutions spatiale qui caractérise l’imagerie fonctionnelle par tomographie à émission mono-photonique (TEMP) ou tomographie à émission de positons (TEP) et peuvent être caractérisés par une perte de signal dans les tissus présentant une taille comparable à celle de la résolution spatiale du système d’imagerie, représentée par sa fonction de dispersion ponctuelle (FDP). Outre ce phénomène, les EVP peuvent également entrainer une contamination croisée des intensités entre structures adjacentes présentant des activités radioactives différentes. Cet effet peut conduire à une sur ou sous estimation des activités réellement présentes dans ces régions voisines. Différentes techniques existent actuellement pour atténuer voire corriger les EVP et peuvent être regroupées selon le fait qu’elles interviennent avant, durant ou après le processus de reconstruction des images et qu’elles nécessitent ou non la définition de régions d’intérêt provenant d’une imagerie anatomique de plus haute résolution(tomodensitométrie TDM ou imagerie par résonance magnétique IRM). L’approche post-reconstruction basée sur le voxel (ne nécessitant donc pas de définition de régions d’intérêt) a été ici privilégiée afin d’éviter la dépendance aux reconstructions propres à chaque constructeur, exploitée et améliorée afin de corriger au mieux des EVP. Deux axes distincts ont été étudiés. Le premier est basé sur une approche multi-résolution dans le domaine des ondelettes exploitant l’apport d’une image anatomique haute résolution associée à l’image fonctionnelle. Le deuxième axe concerne l’amélioration de processus de déconvolution itérative et ce par l’apport d’outils comme les ondelettes et leurs extensions que sont les curvelets apportant une dimension supplémentaire à l’analyse par la notion de direction. Ces différentes approches ont été mises en application et validées par des analyses sur images synthétiques, simulées et cliniques que ce soit dans le domaine de la neurologie ou dans celui de l’oncologie. Finalement, les caméras commerciales actuelles intégrant de plus en plus des corrections de résolution spatiale dans leurs algorithmes de reconstruction, nous avons choisi de comparer de telles approches en TEP et en TEMP avec une approche de déconvolution itérative proposée dans ce mémoire. / Partial Volume Effects (PVE) designates the blur commonly found in nuclear medicine images andthis PhD work is dedicated to their correction with the objectives of qualitative and quantitativeimprovement of such images. PVE arise from the limited spatial resolution of functional imaging witheither Positron Emission Tomography (PET) or Single Photon Emission Computed Tomography(SPECT). They can be defined as a signal loss in tissues of size similar to the Full Width at HalfMaximum (FWHM) of the PSF of the imaging device. In addition, PVE induce activity crosscontamination between adjacent structures with different tracer uptakes. This can lead to under or overestimation of the real activity of such analyzed regions. Various methodologies currently exist tocompensate or even correct for PVE and they may be classified depending on their place in theprocessing chain: either before, during or after the image reconstruction process, as well as theirdependency on co-registered anatomical images with higher spatial resolution, for instance ComputedTomography (CT) or Magnetic Resonance Imaging (MRI). The voxel-based and post-reconstructionapproach was chosen for this work to avoid regions of interest definition and dependency onproprietary reconstruction developed by each manufacturer, in order to improve the PVE correction.Two different contributions were carried out in this work: the first one is based on a multi-resolutionmethodology in the wavelet domain using the higher resolution details of a co-registered anatomicalimage associated to the functional dataset to correct. The second one is the improvement of iterativedeconvolution based methodologies by using tools such as directional wavelets and curveletsextensions. These various developed approaches were applied and validated using synthetic, simulatedand clinical images, for instance with neurology and oncology applications in mind. Finally, ascurrently available PET/CT scanners incorporate more and more spatial resolution corrections in theirimplemented reconstruction algorithms, we have compared such approaches in SPECT and PET to aniterative deconvolution methodology that was developed in this work.