Towards Image-Guided Pediatric Atrial Septal Defect Repair

Congenital heart disease occurs in 107.6 out of 10,000 live births, with Atrial Septal Defects (ASD) accounting for 10\% of these conditions. Historically, ASDs were treated with open heart surgery using cardiopulmonary bypass, allowing a patch to be sewn over the defect. In 1976, King et al. demonstrated use of a transcatheter occlusion procedure, thus reducing the invasiveness of ASD repair. Localization during these catheter based procedures traditionally has relied on bi-plane fluoroscopy; more recently trans-esophageal echocardiography (TEE) and intra-cardiac echocardiography (ICE) have been used to navigate these procedures. Although there is a high success rate using the transcatheter occlusion procedure, fluoroscopy poses radiation dose risk to both patient and clinician. The impact of this dose to the patients is important as many of those undergoing this procedure are children, who have an increased risk associated with radiation exposure. Their longer life expectancy than adults provides a larger window of opportunity for expressing the damaging effects of ionizing radiation. In addition, epidemiologic studies of exposed populations have demonstrated that children are considerably more sensitive to the carcinogenic effects radiation. Image-guided surgery (IGS) uses pre-operative and intra-operative images to guide surgery or an interventional procedure. Central to every IGS system is a software application capable of processing and displaying patient images, registration between multiple coordinate systems, and interfacing with a tool tracking system. We have developed a novel image-guided surgery framework called Kit for Navigation by Image Focused Exploration (KNIFE). This software system serves as the core technology by which a system for reduction of radiation exposure to pediatric patients was developed. The bulk of the initial work in this research endevaour was the development of KNIFE which itself went through countless iterations before arriving at its current state as per the feature requirements established. Secondly, since this work involved the use of captured medical images and their use in an IGS software suite, a brief analysis of the physics behind the images was conducted. Through this aspect of the work, intrinsic parameters (principal point and focal point) of the fluoroscope were quantified using a 3D grid calibration phantom. A second grid phantom was traversed through the fluoroscopic imaging volume of II and flat panel based systems at 2 cm intervals building a scatter field of the volume to demonstrate pincushion and \u27S\u27 distortion in the images. Effects of projection distortion on the images was assessed by measuring the fiducial registration error (FRE) of each point used in two different registration techniques, where both methods utilized ordinary procrustes analysis but the second used a projection matrix built from the fluoroscopes calculated intrinsic parameters. A case study was performed to test whether the projection registration outperforms the rigid transform only. Using the knowledge generated were able to successfully design and complete mock clinical procedures using cardiac phantom models. These mock trials at the beginning of this work used a single point to represent catheter location but this was eventually replaced with a full shape model that offered numerous advantages. At the conclusion of this work a novel protocol for conducting IG ASD procedures was developed. Future work would involve the construction of novel EM tracked tools, phantom models for other vascular diseases and finally clinical integration and use

Designing parametric matter:Exploring adaptive material scale self-assembly through tuneable environments

3D designs can be created using generative processes, which can be transformed and adapted almost infinitely if they remain within their digital design software. For example, it is easy to alter a 3D object's colour, size, transparency, topology and geometry by adjusting values associated with those attributes. Significantly, these design processes can be seen as morphogenetic, where form is grown out of bottom-up logic’s and processes. However, when the designs created using these processes are fabricated using traditional manufacturing processes and materials they lose all of these abilities. For example, even the basic ability to change a shapes' size or colour is lost. This is partly because the relationships that govern the changes of a digital design are no longer present once fabricated. The motivating aim is: how can structures be grown and adapted throughout the fabrication processes using programmable self-assembly? In comparison the highly desirable attribute of physical adaptation and change is universally present within animals and biological processes. Various biological organisms and their systems (muscular or skeletal) can continually adapt to the world around them to meet changing demands across different ranges of time and to varying degrees. For example, a cuttlefish changes its skin colour and texture almost immediately to hide from predators. Muscles grow in response to exercise, and over longer time periods bones remodel and heal when broken, meaning biological structures can adapt to become more efficient at meeting regularly imposed demands. Emerging research is rethinking how digital designs are fabricated and the materials they are made from, leading to physically responsive and reconfigurable structures. This research establishes an interdisciplinary and novel methodology for building towards an adaptive design and fabrication system when utilising material scale computation process (e.g. self-assembly) within the fabrication process, which are guided by stimuli. In this context, adaption is the ability of a physical design (shape, pattern) to change its local material and or global properties, such as: shape, composition, texture and volume. Any changes to these properties are not predefined or constrained to set limits when subjected to environmental stimulus, (temperature, pH, magnetism, electrical current). Here, the stimulus is the fabrication mechanisms, which are governed and monitored by digital design tools. In doing so digital design tools will guide processes of material scale self-assembly and the resultant physical properties. The fabrication system is created through multiple experiments based on various material processes and platforms, from paint and additives, to ink diffusion and the mineral accretion process. A research through design methodology is used to develop the experiments, although the experiments by nature are explorative and incremental. Collectively they are a mixture of analogue and digital explorations, which establish principles and a method of how to grow physical designs, which can adapt based on digital augmentations by guiding material scale self-assembly. The results demonstrate that it is possible to grow physical 2D and 3D designs (shapes and patterns) that could have their properties tuned and adapted by creating tuneable environments to guide the mineral accretion process. Meaning, the desirable and dynamic traits of digital computational designs can be leveraged and extended the as they are made physical. Tuneable environments are developed and defined thought the series experiments within this thesis. Tuneable environments are not restricted to the mineral accretion process, as it is demonstrated how they can manipulate ink cloud patterns (liquid diffusion), which are less constrained in comparison to the mineral accretion process. This is possible due to the use of support mediums that dissipate energy and also contrast materially (they do not diffuse). Combining contrasting conditions (support mediums, resultant material effects) with the idea of tuneable environments reveals how: 1) material growth and properties can be monitored and 2) the possibilities of growing 3D designs using material scale self-assembly, which is not confined to a scaffold framework. The results and methodology highlight how tuneable environments can be applied to advance other areas of emerging research, such as altering environmental conditions during methods of additive manufacturing, such as, suspended deposition, rapid liquid printing, computed axial lithography or even some strategies of bioprinting. During the process, deposited materials and global properties could adapt because of changing conditions. Going further and combining it with the idea of contrasting mediums, this could lead to new types 3D holographic displays, which are grown and not restricted to scaffold frameworks. The results also point towards a potential future where buildings and infrastructure are part of a material ecosystem, which can share resources to meet fluctuating demands, such as, solar shading, traffic congestion, live loading

Algebraic Number Starscapes

We study the geometry of algebraic numbers in the complex plane, and their Diophantine approximation, aided by extensive computer visualization. Motivated by these images, called algebraic starscapes, we describe the geometry of the map from the coefficient space of polynomials to the root space, focussing on the quadratic and cubic cases. The geometry describes and explains notable features of the illustrations, and motivates a geometric-minded recasting of fundamental results in the Diophantine approximation of the complex plane. The images provide a case-study in the symbiosis of illustration and research, and an entry-point to geometry and number theory for a wider audience. The paper is written to provide an accessible introduction to the study of homogeneous geometry and Diophantine approximation. We investigate the homogeneous geometry of root and coefficient spaces under the natural $\operatorname{PSL}(2;\mathbb{C})$ action, especially in degrees 2 and 3. We rediscover the quadratic and cubic root formulas as isometries, and determine when the map sending certain families of polynomials to their complex roots (our starscape images) are embeddings. We consider complex Diophantine approximation by quadratic irrationals, in terms of hyperbolic distance and the discriminant as a measure of arithmetic height. We recover the quadratic case of results of Bugeaud and Evertse, and give some geometric explanation for the dichotomy they discovered (Bugeaud, Y. and Evertse, J.-H., Approximation of complex algebraic numbers by algebraic numbers of bounded degree, Ann. Sc. Norm. Super. Pisa Cl. Sci. (5) 8 (2009), no. 2, 333-368). Our statements go a little further in distinguishing approximability in terms of whether the target or approximations lie on rational geodesics. The paper comes with accompanying software, and finishes with a wide variety of open problems.Comment: 63 pages, 36 figures; this version includes a technical introduction for an expert audienc

Modeling Fine Sediment Behavior in Gravel-Bed Rivers

Fine-grained sediment accumulation in the interstices of gravel beds is a key factor in degrading riverine habitats. However, interstitial deposits are highly dynamic and are not sufficiently understood. This work enhances the understanding of interstitial fine sediment deposition by investigating interstitial storage and ingress, flow, suspended sediment and gravel bed character. Furthermore, this work introduces a numerical suspended sediment deposition model with the power to predict patterns of interstitial ingress. The investigation of interstitial deposition were carried out on two levels. Both data orginating from flume experiments and from three locations of the River Culm, Devon, UK was collected. The experimental data showed the significant influence of small scale variations in flow and bed character and their influence on interstitial ingress. The field investigation showed clear differences in interstitial fine-grained sediment for the different river reaches and an overall higher interstitial ingress compared to recent published data. The numerical model development was realised in a two-step approach. First, the model was coded and calibrated for the flume scale processes and, second, an upscaled reach scale model was devolped for the field data. This reach scale suspended sediment deposition model included flow information, for which depthaveraged two dimensional hydrodynamic models were developed with the software Delft3D. The overall explanatory power of the model at this state is not satisfactory with regards to local deposition distribution. A separate chapter discusses the possible causes and implications of this short coming for further research from a data aquisition and modelling perspective.Great Western Research, ADAS U

Deeply Learned Priors for Geometric Reconstruction

This thesis comprises of a body of work that investigates the use of deeply learned priors for dense geometric reconstruction of scenes. A typical image captured by a 2D camera sensor is a lossy two-dimensional (2D) projection of our three-dimensional (3D) world. Geometric reconstruction approaches usually recreate the lost structural information by taking in multiple images observing a scene from different views and solving a problem known as Structure from Motion (SfM) or Simultaneous Localization and Mapping (SLAM). Remarkably, by establishing correspondences across images and use of geometric models, these methods (under reasonable conditions) can reconstruct a scene's 3D structure as well as precisely localise the observed views relative to the scene. The success of dense every-pixel multi-view reconstruction is however limited by matching ambiguities that commonly arise due to uniform texture, occlusion, and appearance distortion, among several other factors. The standard approach to deal with matching ambiguities is to handcraft priors based on assumptions like piecewise smoothness or planarity in the 3D map, in order to "fill in" map regions supported by little or ambiguous matching evidence. In this thesis we propose learned priors that in comparison more closely model the true structure of the scene and are based on geometric information predicted from the images. The motivation stems from recent advancements in deep learning algorithms and availability of massive datasets, that have allowed Convolutional Neural Networks (CNNs) to predict geometric properties of a scene such as point-wise surface normals and depths, from just a single image, more reliably than what was possible using previous machine learning-based or hand-crafted methods. In particular, we first explore how single image-based surface normals from a CNN trained on massive amount of indoor data can benefit the accuracy of dense reconstruction given input images from a moving monocular camera. Here we propose a novel surface normal based inverse depth regularizer and compare its performance against the inverse depth smoothness prior that is typically used to regularize regions in the reconstruction that are textureless. We also propose the first real-time CNN-based framework for live dense monocular reconstruction using our learned normal prior. Next, we look at how we can use deep learning to learn features in order to improve the pixel matching process itself, which is at the heart of multi-view geometric reconstruction. We propose a self-supervised feature learning scheme using RGB-D data from a 3D sensor (that does not require any manual labelling) and a multi-scale CNN architecture for feature extraction that is fast and eficient to run inside our proposed real-time monocular reconstruction framework. We extensively analyze the combined benefits of using learned normals and deep features that are good-for-matching in the context of dense reconstruction, both quantitatively and qualitatively on large real world datasets. Lastly, we explore how learned depths, also predicted on a per-pixel basis from a single image using a CNN, can be used to inpaint sparse 3D maps obtained from monocular SLAM or a 3D sensor. We propose a novel model that uses predicted depths and confidences from CNNs as priors to inpaint maps with arbitrary scale and sparsity. We obtain more reliable reconstructions than those of traditional depth inpainting methods such as the cross-bilateral filter that in comparison offer few learnable parameters. Here we advocate the idea of "just-in-time reconstruction" where a higher level of scene understanding reliably inpaints the corresponding portion of a sparse map on-demand and in real-time.Thesis (Ph.D.) -- University of Adelaide, School of Computer Science, 201

The imperfect woman: femininity and British cinema, 1945-1958

This thesis investigates the reconstruction of femininity in Britain in the post-war period (1945-1958). This is carried out through an examination of the socioeconomic and cultural formation of the period, contemporaneous cultural commentaries, contemporary critical writing about the cinema audience, and selected British films from the period, including a detailed study of Yield to the Night (1956). The thesis utilises a range oftheoretical approaches to these issues - film theory, feminist theory and epistemology, social and oral history, discourse theory and textual analysis. The methodological framework of the thesis reflects its feminist concerns and, in tum, engages with debates within feminist theory concerning questions of methodology and epistemology. Accordingly, the first chapter outlines the methodological framework of the thesis as well as situating it in relation to published work in similar areas. In addition, this chapter introduces the themes of the subsequent chapters and clarifies certain key terms used throughout. The second chapter concentrates on the socio-economic and cultural formation of the period 1945-1958 and argues that this period is marked by particular discursive formations - 'Austerity', 'Affluence' and' Americanisation'. These are then discussed in relation to the ways that they are gendered and thus promote prescribed forms of femininity and womanliness. Chapter three focuses on the presentation of the period in terms of women's experiences of the time. This is achieved through an analysis of the tensions between domesticity, women's entry into the labour market and the discursive pressures on women at this time. Chapter four extends the arguments presented in the previous chapters with reference to selected films from the period - Dance Hall (1950), Turn the Key Softly (1953) and Woman in a Dressing Gown (1957), which is discussed with reference to Brief Encounter (1945). Chapter five analyses two film publications from the period - Penguin Film Review (1946-1949) and The Picturegoer (1931-1960) - in order to establish the discursive construction of the female cinema audience. Finally, Chapter six is an in-depth analysis of Yield to the Night (1956) with respect to critical and audience reception of the film and the issue of the construction of 'Affluent femininity.

Ontologzed Ethics: New Essays in African Meta-ethics

Ontologized Ethics: New Essays in African Meta-Ethics examines an often neglected meta-ethical issue in African philosophical discourse: the extent to which one’s orientation of being, or idea of what-is – as an individual or as a group of persons – does, or should, determine one’s concept of the good. To what extent is ethics, or our idea of what is permissible or impermissible, grounded on ideas of what fundamentally exists or what it means to be? The aim of this collection of essays, with emphasis on an African philosophical context, will be to establish more firmly and vigorously whether there is an intrinsic link between ontology and morality – that is, whether, and, if so, how the proper norms for human actions can be explained and validated once we make lucid ideas about metaphysical topics such as human nature, community, relationality and spirituality. The essays included in this volume focus rigorously on ethical issues such as communalism, adultery, environmental ethics, and bioethics with the primary aim of showing whether the link between such issues and metaphysical beliefs is trivial or intrinsic

De l'étude fondamentale des intéractions en solution à la conception de matériaux hybrides à base de polyoxométallates

Herein, we report the use of 1H DOSY NMR methodology to track the interaction between aninorganic multireceptor capsule, referring to the well-defined spherical Keplerate-type{Mo132} ion and a series of organic cation (including tetraalklylammonium). The obtainedresults reveal a strong dependence of the self-diffusion coefficient of the cationic guestsbalancing from the solvated to the plugging situations. Quantitative analysis of the data basedon two-site exchange regime, involving the 20 independent {Mo9O9} receptors of the capsule,allowed determining the stability constants associated to the plugging process of the pores.Surprisingly, the affinity of the capsule for a series of cationic guests increases continuouslywith its apolar character. Such observations evidence that the major factor dictating selectivityin the trapping process is mainly the so-called “hydrophobic effect”.Further investigation focused on the design of Keplerate-based materials where theammonium cations was replaced by imidazolium cations. The obtained materials werecharacterized in the solid state by FT-IR, TGA and elemental analysis. These materials exhibitliquid crystalline phase as evidenced by polarized optical microscopy and DSC, however,folding of the alkyl chain prohibit the formation of well organized mesophase. Finally, thisstrategy was extended to cyclic [Na2K2{Mo4O4S4(H2O)3(OH)2}2(P8W48O184)]32- which wasisolated as DODA or imidazolium salt. Solid state NMR evidence the well organization of thesolid. The obtained materials exhibit smectic A liquid crystalline phase and packed ashexagonal lamellar arrangement in the solid state.La première partie de ce mémoire concerne l’étude en solution de systèmes à base de POMset de cations organiques de polarité/taille variables. Ainsi, l’étude des interactions entre unanion Keplerate noté {Mo132} et une large série de cations organiques (composée d’ions alkylammonium AA) a nécessité la mise en place d’une méthodologie spécifique utilisant la RMNDOSY de 1H. La méthode s’est révélée particulièrement efficace et a permis non seulement demettre clairement en évidence l’existence d’interactions anion-cation fortes mais aussil’extraction des constantes d’association à partir d’un traitement quantitatif des données. Cetteétude révèle que le facteur qui domine le processus d’association anion-cation résulte d’un« effet hydrophobe » directement lié au caractère apolaire du cation organique et polaire dusolvant. Les constantes de stabilité sont en accord avec des interactions plutôt fortes. ParParailleurs, une expérience spécifique a permis de titrer les 20 pores présents à la surface de l’ionKeplérate, montrant ainsi la spécificité du processus d’association.La seconde partie de ce mémoire concerne la conception de matériaux à base de Képlerate enjouant sur la nature des cations imidazolium qui lui sont associés. Les phases solides ont étécaractérisées par spectrométrie infrarouge, analyse élémentaire, EDX et analysethermogravimétrique. Ces études montrent que dans certaines conditions, ces systèmes seaffichent un comportement type cristal liquide.La troisième partie s’intéresse spécifiquement aux interactions ionique et/ou van der Waals àl’origine de phénomènes de structuration. L’anion cyclique[Na2K2{Mo4O4S4(H2O)3(OH)2}2(P8W48O184)]32- ( noted 1) a été isolé à l’état solide sous laforme de sels de DODA (dioctadécyl-diméthyl-ammonium) ou d’imidazolium. L’analysestructurale de ces phases par RMN MAS de 1H, 13C et 31P montre sans ambigüitél’organisation des chaines alkyles. Ces résultats croisés avec la microscopie optique polarisée,l’analyse thermique différentielle et la diffraction des rayons X aux petits angles montrentclairement la formation de phases mésomorphes lamellaires dont l’espacement estdirectement lié à la longueur des chaines alkyles