Thesis (M.S.E.C.E.)--University of Delaware, 2007. / Principal faculty advisors: Fouad Kiamilev and Robert F. Rogers, Dept. of Electrical and Computer Engineering. Includes bibliographical references.

Thesis (M.C.E.)--University of Delaware, 2006. / Principal faculty advisor: James T. Kirby, Dept. of Civil & Environmental Engineering. Includes bibliographical references.

Thesis (M.Phil.)--Hong Kong University of Science and Technology, 2007. / Includes bibliographical references (leaves 55-60). Also available in electronic version.

Thesis (Ph.D.)--Hong Kong University of Science and Technology, 2007. / Includes bibliographical references (leaves 151-166). Also available in electronic version.

The osteoclast ruffled border is a highly convoluted, complex membrane that is necessary for bone resorption. It is thought to form following mass lysosomal fusion with the boneapposing plasma membrane and vesicular trafficking is vital for its formation and function. The aim of this PhD was to better understand the ultrastructure, formation and function of the ruffled border using TEM and advanced imaging techniques. Ruffled border reformation following calcitonin treatment was visualised and the stages of ruffled border formation were described. Ruffled borders in healthy and osteopetrotic osteoclasts were also imaged by TEM and characterised using a morphological grading system. The key findings of this thesis are as follows: (1) vacuoles, not lysosomes, are the primary contributors of membrane to the ruffled border and the membrane projections of the ruffled border form passively as a consequence of channel formation, not actively by membrane folding, (2) extracellular vesicles are located, and appear to be released, at the ruffled border. Various functional aspects of the ruffled border were also investigated. Vesicles near the ruffled border were identified and characterised by immunoelectron microscopy based on their content and morphology. We found no morphological defects in ruffled borders in mice deficient in Plekhm1. In osteoclasts derived from patients with a SNX10 mutation, we found that while the cells retained the capacity to form well-developed ruffled borders, they did so less often than healthy control osteoclasts. Importantly, we observed that even in a population of healthy osteoclasts, ruffled border morphology is highly heterogeneous because they are at different stages in the resorption cycle. In conclusion, the data in this thesis provide novel findings, previously unseen details regarding how resorbing osteoclasts interact with the bone surface, and have revealed unique insights into ruffled border morphology, formation and the vesicles with which it interacts.

Scattering from X-ray Mirrors deals with the the phenomena observed when x-rays are reflected from high quality mirror surfaces at grazing incidence. The presence of micro- irregularities in the reflecting surface causes power to be deviated away from the specular direction and into the wings of the angular distribution of radiation. Both theoretical and experimental investigations are presented. The two principal theories of the scattering of electromagnetic radiation are reviewed and are shown to produce identical results in the smooth surface limit. The scalar theory is further developed so as to be applicable to a scattering surface which can be described by an arbitrary surface height distribution function for any surface autocovariance function. The theoretical advances reported suggest a means by which the surface height distribution statistics of mirror surfaces might be derived from experimental scattering measurements. The experimental work in the thesis deals with a scattering experiment designed to test these theoretical developments. The development work involved in the construction of the Variable Angle Scattering Experiment (VASE) is presented and the anomalous results obtained from scattering measurements from two test flat x-ray mirrors are discussed. A shadowing model is devised to account for the anomalous results from the VASE. The shadowing model is then shown to be in good agreement with the VASE data and with data from other scattering experiments. The shadowing model, which provides a means of measuring the properties of pure mirror surfaces, is further developed to enable measurements of surface structure on mirrors which have become specked with small sparse contaminant features, thus allowing highly sensitive estimates of contaminant density and height to be made.

No description available.

The restoration of images degraded by a stochastic, time varying point spread func-tion(PSF) is addressed. The object to be restored is assumed to remain fixed during the observation time. A sequence of observations of the unknown object is assumed available. The true value of the random PSF is not known. However, for each observation a "noisy" measurement of the random PSF at the time of observation is assumed available. Practical applications in which the PSF is time varying include situations in which the images are obtained through a nonhomogeneous medium such as water or the earth's atmosphere. Under such conditions, it is not possible to determine the PSF in advance, so attempts must be made to extract it from the degraded images themselves. A measurement of the PSF may be obtained by either isolating a naturally occurring point object in the scene, such as a reference star in optical astronomy, or by artificially installing an impulse light source in the scene. The noise in the measurements of point spread functions obtained in such a manner are particularly troublesome in cases when the light signals emitted by the point object are not very strong. In this thesis, we formulate a model for this restoration problem with PSF measurement error. A maximum likelihood filter and a Wiener filter are then developed for this model. Restorations are performed on simulated degraded images. Comparisons are made with standard filters of the classical restoration model(ignoring the PSF error), and also with results based on the averaged degraded image and averaged PSF's. Experimental results confirm that the filters we developed perform better than those based on averaging and than those ignoring the PSF measurement error. / Applied Science, Faculty of / Electrical and Computer Engineering, Department of / Graduate

This thesis presents an algorithm for image reconstruction from projections intended for use in a new class of volume imaging PET scanners. The algorithm is based on the inversion of the three dimensional Radon Transform as it applies to the truncated cylindrical detector geometry and is derived from the X-ray Transform inversion given by the Orlov recovery operator. The algorithm is tested using Monte Carlo simulations of several phantom geometries and employs a single iterative step to include all detected events in the reconstruction. The reconstructed images are good representations of the original objects, however the iterative step is a source of some significant artefacts in the images. Also discussed is the extension of the Radon Transform technique to a non-iterative method for three dimensional image reconstruction using all detected events. / Science, Faculty of / Physics and Astronomy, Department of / Graduate

Technological advances in image acquisition speeds and new contrast agents, in both clinical and basic research settings, have enabled entirely new approaches to functional imaging in living systems. Analysis of dynamic and multidimensional data requires very different approaches to the classical segmentation and visualization tools developed for purely structural or anatomical imaging. This thesis details the development of two different spatiotemporal analysis approaches for high-speed in-vivo dynamic optical imaging. Optical imaging is a diverse, versatile, and generally inexpensive modality that can take advantage of a wide range of endogenous and exogenous sources of optical contrast within living tissue. While light scattering can limit resolution and sensitivity of imaging in deeper tissues, optical imaging is well suited for small animal studies where it can be used for studies of physiology and disease processes, for pharmaceutical development and as a test-bed for translation to clinical applications. In the first part of this work, we present and apply spatiotemporal analysis techniques which we define as `dynamic contrast enhancement' methods. We apply these methods to in-vivo whole body small animal molecular optical imaging to demonstrate that dynamic analysis can be used for longitudinal assessment of organ function. We then demonstrate the equivalence of our approach to dynamic contrast enhanced magnetic resonance imaging. This optical technique could allow for better informed drug development and longitudinal toxicity evaluation. This technique could also serve as a platform for the development of functional imaging methods using dynamic MRI. We then apply spatiotemporal analysis techniques to high speed optical hemodynamic imaging data acquired on the exposed rodent cortex. The purpose of this work is to develop a mechanistically-based spatiotemporal model of neurovascular coupling, in order to better understand the basis of functional magnetic resonance imaging data in the human brain. Our results also provide new insights into potential links between neurovascular disruption and disease pathophysiology in the brain.