Dissertations / Theses: 'Medical and biomedical engineering'

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Stanier, Jeffrey. "Segmentation and editing of 3-dimensional medical images." Thesis, University of Ottawa (Canada), 1994. http://hdl.handle.net/10393/10031.

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Neuroradiologists rely on scanned images of the human brain to diagnose many pathologies. The images, even those collected in 3-dimensions, are typically displayed as a 2-dimensional collage of slices and much of the intrinsic 3-D structure of the data is lost. Image Atlases are commonly used to delineate and label Volumes Of Interest (VOIs) in 3-dimensional, slice-type, medical data sets. They can serve many purposes: to highlight important regions, to quantify the size and shape of structures in the images, to define a surface for 3-D rendering and to help in navigation through a series of images. To perform these functions, an individual atlas is required for each data set. The purpose of this thesis is to develop a link between the volume data and the individual atlas associated with each set of images. An automatic method of building an individual atlas from the volume data is proposed. The method uses a data-driven, bottom-up segmentation to produce a primitive atlas followed by a knowledge-driven, top-down merging and labelling stage to refine the primitive atlas into an individual atlas. The system was implemented in software using an object-oriented approach which allowed for a high quality user interface and a flexible and efficient implementation of the concepts of an atlas and a VOI. Tests were performed to judge the quality of the segmentations and of the atlas labellings. The results prove that the individual atlases created using the proposed method are sufficiently accurate to aid in visualizing 3-D structures in medical data sets and to quantify the sizes of these structures.

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Zhang, Hongbin. "Signal detection in medical imaging." Diss., The University of Arizona, 2001. http://hdl.handle.net/10150/290512.

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The goal of this research is to develop computational methods for predicting how a given medical imaging system and reconstruction algorithm will perform when mathematical observers for tumor detection use the resulting images. Here the mathematical observer is the ideal observer, which sets an upper limit to the performance as measured by the Bayesian risk or receiver operating characteristic analysis. This dissertation concentrates on constructing the ideal observer in complex detection problems and estimating its performance. Thus the methods reported in this dissertation can be used to approximate the ideal observer in real medical images. We define our detection problem as a two-hypothesis detection task where a known signal is superimposed on a random background with complicated distributions and embedded in independent Poisson noise. The first challenge of this detection problem is that the distribution of the random background is usually unknown and difficult to estimate. The second challenge is that the calculation of the ideal observer is computationally intensive for non stylized problems. In order to solve these two problems, our work relies on multiresolution analysis of images. The multiresolution analysis is achieved by decomposing an image into a set of spatial frequency bandpass images so each bandpass image represents information about a particular fitness of detail or scale. Connected with this method, we will use three types of image representation by invertible linear transforms. They are the orthogonal wavelet transform, pyramid transform and independent component analysis. Based on the findings from human and mammalian vision, we can model textures by using marginal densities of a set of spatial frequency bandpass images. In order to estimate the distribution of an ensemble of images given the empirical marginal distributions of filter responses, we can use the maximum entropy principle and get a unique solution. We find that the ideal observer calculates a posterior mean of the ratio of conditional density functions, or the posterior mean of the ratio of two prior density functions, both of which are high dimensional integrals and have no analytic solution usually. But there are two ways to approximate the ideal observer. The first one is a classic decision process; that is, we construct a classifier following feature extraction steps. We use the integrand of the posterior mean as features, which are calculated at the estimated background close to the posterior mode. The classifier combines these features to approximate the integral (or the ideal observer). Finally, if we know both the conditional density function and the prior density function then we can also approximate the high dimensional integral by Monte Carlo integration methods. Since the calculation of the posterior mean is usually a very high dimensional integration problem, we must construct a Markov chain, which can explore the posterior distribution efficiently. We will give two proposal functions. The first proposal function is the likelihood function of random backgrounds. The second method makes use of the multiresolution representation of the image by decomposing the image into a set of spatial frequency bands. Sampling one pixel in each band equivalently updates a cluster of pixels in the neighborhood of the pixel location in the original image.

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Do, Khoa Tat. "Universal Engineering Programmer - An In-house Development Tool For Developing and Testing Implantable Medical Devices In St. Jude Medical." DigitalCommons@CalPoly, 2011. https://digitalcommons.calpoly.edu/theses/488.

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During development and testing of the functionality of the pacemaker and defibrillator device, engineers in the St. Jude Medical Cardiac Rhythm Management Division use an in-house development tool called Universal Engineering Programmer (UEP) to ensure the device functions as expected, before it can be used to test on an animal or a human during the implantation process. In addition, some applications of UEP are incorporated into the official releases of the device product. UEP has been developed and used by engineers across departments in the St. Jude Medical Cardiac Rhythm Management Division (CRMD). This thesis covers the flexible and reusable design and implementation of UEP features, to allow engineers to easily and effectively develop and test the devices.

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Kasrai, Reza. "On the perception of transparency : psychophysics and applications to medical image visualisation." Thesis, McGill University, 2002. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=38493.

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Transparency is used routinely as part of a host of visualisation functionalities in software applications for image-guided procedures, though little research is devoted to the rigorous validation of the use of transparency in clinical visualisation. This thesis presents three psychophysical studies aiming to understand how the human visual system interacts with transparent stimuli. The first sets out to measure the performance of users in a 3-D manual segmentation task. Visualising the stimuli in stereo improved performance, though no effect of transparent surface rendering was revealed. In addition, subjects performed better using a standard 2-D mouse compared to a 3-D tracking device. The next two studies explore the intensity and figural conditions for perceptual transparency using a novel six-luminance stimulus. While a number of models of intensity conditions have been previously proposed, it was found that the luminance-based formulation of Metelli's episcotister model, and a model based on ratios of Michelson contrasts best predicted the subjects' settings, which were found to be very precise. The results also showed that there exists a reasonably wide range of stimuli that give rise to at least some degree of perceived transparency. It was demonstrated that the relative arrangement of the colours around contour crossings (X-junctions) was a salient feature indicating to the visual system the plausibility of a transparent filter and the depth ordering of layers. In addition, the occlusion of X-junctions and perturbation of the orientation of a transparent filter's contours at the junction gave rise to reductions in performance, indicating the importance of junctions in transparency perception.

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Lorimer, C. J. "Stimuli responsive polymers as medical implants." Thesis, Queen's University Belfast, 2002. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.269126.

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Xiao, Xiao. "Development and control of a multi-dimensional micromanipulation system for bio-medical engineering." Thesis, University of Macau, 2017. http://umaclib3.umac.mo/record=b3691055.

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Tang, Selina Vi Yu. "Synthesis of nanomaterials for biomedical applications." Thesis, University of Nottingham, 2014. http://eprints.nottingham.ac.uk/14101/.

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The field of nanotechnology is growing vastly, both as a field of research and in commercial applications. This rapid growth calls for synthesis methods which can produce high quality nanomaterials, while being scalable. This thesis describes an investigation into the use of a continuous hydrothermal reactor for the synthesis of nanomaterials, with potential use in three different biomedical applications – bone scaffolds, fluorescent biomarkers, and MRI contrast agents. The first chapter of this thesis provides an overview of nanotechnology: the advantages of nanoscale, the commercial industries which can benefit, and the predominant methods currently used to produce nanomaterials. Some advantages and drawbacks of each synthesis route are given, concluding with a description of the Nozzle reactor – the patented technology used for nanomaterial synthesis in this Thesis. Chapter 2 then focusses on the characterisation techniques used in this thesis, detailing the principles of how data is obtained, as well as highlighting the limitations of each method. With the background information in place, chapters 3, 4 and 5 describe more specific nanomaterials and how they can be applied to each of the aforementioned biomedical fields. These chapters provide the technical details of how various nanomaterials can be synthesised using the Nozzle reactor, and the structural data (crystallinity, particle size) obtained from these samples. Furthermore, the functional properties of these nanomaterials are tested and the results, along with a discussion of any trends, are presented. Finally, this thesis concludes with a summary of the results described and emphasises the key areas where further work can be conducted.

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Koo, Jahyun. "Accelerating a medical 3D brain MRI analysis algorithm using a high-performance reconfigurable computer." Thesis, McGill University, 2007. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=18480.

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Many automatic algorithms have been proposed for analyzing Magnetic Resonance Imaging (MRI) data sets. These algorithms allow clinical researchers to analyze their quantitative data with consistently accurate results. With the increasingly large data sets being used in brain mapping, there has been a significant rise in the need for methods to accelerate these algorithms, as their computation can consume many hours. This thesis presents the results from a study on implementing such quantitative analysis algorithms on High-Performance Reconfigurable Computers (HPRCs). The Partial Volume Estimation (PVE), a brain tissue classification algorithm for MRI, was implemented on two SGI RASC RC100 systems using the Mitrion-C High-Level Language (HLL). The CPU-based PVE algorithm was profiled to identify the computationally intensive functions and two floating-point functions, estimating the probability densities (PDs) of tissues and the prior information, were implemented on FPGA-accelerators. Several simulated and real human brain MR images were used to evaluate the accuracy and performance improvement of the FPGA-based PVE algorithm. The Sensitivity and Kappa coefficients were calculated to verify the accuracy of the images resulting from the FPGA-based implementation. The FPGA-based PDs estimation and prior information estimation function achieved an average speedup of 2.5X and 9.4X, respectively. The overall performance improvement of the FPGA-accelerated PVE algorithm over the conventional CPU-based algorithm was 5.1X with four FPGAs.
Plusieurs algorithmes ont été proposés pour l'analyse des données d'imagerie par résonance magnétique (IRM). Ceux-ci ont permis aux chercheurs cliniques d'analyser leurs données avec précision jusqu'à tout récemment. Mais avec l'augmentation des données quantitatives à analyser dans le domaine de l'imagerie du cerveau, il y a un besoin maintenant pour des méthodes pour accélérer ces algorithmes surtout que leur temps de calcul peut prendre plusieurs heures. Cette thèse présente le résultat d'une étude sur l'implémentation de ces algorithmes sur des ordinateurs reconfigurables à haute performance. L'estimation de volume partiel (PVE), un algorithme de classification du tissu de cerveau a été implémenté sur deux systémes SGI RASC RC100 qui utilisent le langage de haut niveau Mitrion-C. L'algorithme PVE sur processeur a été profilé pour identifier les fonctions intensives en temps de calcul et deux fonctions à virgule flottante estimant les densités de probabilité de tissus et l'information antérieure ont été implémenté sur des accélérateurs FPGA. Plusieurs images de cerveau humain simulées et réelles ont été utilisées pour vérifier la précision et l'amélioration en performance de l'algorithme PVE sur FPGA. Les coefficients de sensitivité et kappa ont été mesurés dans le but de vérifier la précision des images de l'implémentation sur FPGA. L'estimation des densités de probabilité sur FPGA et la fonction d'estimation d'information antérieure ont eu pour résultat des gains de performance de 2.5 et 9.4, respectivement. La performance globale de l'amélioration de l'algorithme PVE sur FPGA comparativement à l'algorithme établie sur processeur a été de 5.1 sur quatre processeurs.

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Carey, Jason. "Axial, flexural and torsional rigidities of two-dimensional braided fibre composite medical catheters." Thesis, University of Ottawa (Canada), 2003. http://hdl.handle.net/10393/28979.

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The development of a one-piece braided model catheter with the same rigidities as the combined medical catheter-guidewire system presently employed during cardiovascular catheterization procedures is the principal goal of this research. This will result in a significant reduction in the time required to insert a cardiovascular catheter. This is also the first and fundamental step in the development of optimal rigidity cardiovascular catheters. To begin, the axial, torsional and flexural rigidities of existing medical catheters were reviewed and measured. A model to predict the longitudinal tensile and in-plane shear moduli of 2D braided structures, needed for the calculations of the axial, torsional and flexural rigidities of braided tubes, was developed. The sensitivity of the model to key constituent and laminar properties was analysed. It was concluded that accurate values of Efl1, E m and Gm are required for the micromechanical model; the model is not sensitive to the remaining elastic constants (nuf12, nu f23, Gfl2, G23). Oversized braided (Kevlar 49 fibre and thermoset matrix) engineering model composite structures---or model catheters---have been used to verify the model. These model catheters have been produced on an existing braiding machine. Kevlar 49 fibre and epoxy resin have been used primarily because the laminar mechanical properties have been measured in a previous experimental study by Flanagan and Munro [72]. There was good agreement (approximately 6%) between the predicted and measured values of the longitudinal elastic modulus of braided tubes which provided confidence in the model. Shear modulus predictions and the range of experimental results also showed reasonable agreement. The results also show that micromechanical models in which accurate values for important elastic constants (Ef11, Em and G m) are used can accurately predict the experimental results. The preceding experimental work was carried out for full coverage rigid thermoset matrix braided fibre composites. Actual medical catheters require flexible matrix and an open fibre mesh rather than full fibre coverage; therefore, it was necessary to select the appropriate matrix and reinforcement for an actual medical catheter. The proposed CLPT model was used to select the appropriate fibre and resin to obtain rigidities similar to those of the existing medical catheter-guidewire systems. Laminar elastic constants were estimated using micromechanical models. The proposed CLPT model reasonably predicted the longitudinal elastic and shear moduli of model catheters produced with one of the selected elastomeric resins. (Abstract shortened by UMI.)

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Lang, Alexandra R. "Medical device design for adolescents." Thesis, University of Nottingham, 2012. http://eprints.nottingham.ac.uk/12501/.

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Adolescents have been identified as users of medical devices who are currently overlooked in the design and development of these products. This research presents a set of studies that investigate the non-clinical user requirements of adolescent medical device users. Interviews with a range of healthcare professionals provided guidance into chronic conditions and devices which are relevant to adolescent populations. Workshops involving healthy adolescents in schools were carried out to elicit adolescent perspectives of current medical device design. The results of this study showed that the range of medical devices presented did not satisfy adolescent user requirements and provided insight into factors which are important to this specific user group. The workshop also identified the acapella® physiotherapy device, used for chest and airway clearance in the treatment of cystic fibrosis, as a suitable case study for further evaluation with real adolescent users. Case study interviews were carried out with adolescents with cystic fibrosis: the users of the acapella®. The interviews identified a range of unmet requirements and expanded on the results from the workshops. In addition to the more general design factors, users of the acapella® highlighted the effect of device use on clinical effectiveness. The data from the workshops and case study interviews was used in a co-design project with an adolescent user of the device. A design specification was interpreted from the data to produce a visual representation of the adolescent requirements. The research has produced two outputs. The first is the development of a prototype tool for eliciting adolescent design priorities for medical devices - The Adolescent Medical Device Assessment Tool (AMDAT) The second deliverable is a set of guidelines which detail the specific requirements and goals of adolescent users of medical devices - Adolescent Medical Device Requirements. This guidance aims to facilitate the consideration of adolescent user requirements in the design and development of new medical devices. The research investigation has contributed new understanding to the fields of human factors and adolescent healthcare. The findings from these studies demonstrate how adolescent populations can be successfully engaged in research tasks. This research investigation has shown that adolescents have specific needs of medical devices and that meeting these needs through user-centred methods may lead to better adherence of use and improved health outcomes.

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Black, Fiona E. "The characterisation and interactions of biomedical polymers." Thesis, University of Nottingham, 1999. http://eprints.nottingham.ac.uk/29655/.

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As the world population grows and the standard of living increases a need for better health care is an important consideration. Over the latter half of this century the use of polymeric materials within the field of medicine has grown considerably. This thesis investigates a variety of novel polymers whose applications within the medical field are both important and varied. In the cases studied, as with other polymeric materials intended for medicinal uses, the interaction with their surfaces is important, as when placed in the body the surface is the first place of contact and hence interaction with the system. Because of the importance of these surface interactions, which can elicit both beneficial and detrimental effects, this thesis is concerned with the surface chemistry and the relationship of this property to the interfacial interactions of the polymeric systems investigated. Chapter 1 will concentrate on providing a historical overview of the field of polymers, especially the applications in the biomedical field. The surface analytical techniques of surface plasmon resonance (SPR), atomic force microscopy (AFM), X-ray photoelectron spectrometry (XPS) and secondary ion mass spectrometry (SIMS) utilised in this the is to investigate the surface properties of the materials of interest will also be introduced. The demand for organ transplants far outweighs the supply of donor organs. Therefore, many patients with a variety of disease die each year. If new organs could be grown utilising the patients own cells, the supply of organs could be increased to meet the demand and these custom grown organ would not nave the problems of rejection as observed with donor ones. This is what tissue engineering aims to do. By utilising polymer matrices, to provide a scaffold for the tissue to grow in the correct configuration and a variety of growth factors and cell signalling agents to ensure the correct differentiation and function of the cells, it is hoped in the future new organs for example lung and livers will be able to be grown on demand. Chapter 3 and 4 concentrate on the in depth study of a polymer intended for such an application. Chapter 3 concentrates on determining the surface chemistry of this polymer system. XPS and SIMS are used to identify the type of chemical groups present at the surface and quantify their contribution to the overall surface layer. Chapter 4, probes the interactions, both specific and non specific with this system using a variety of complementary techniques. SPR is utilised to quantify the extent and rate of the interactions, whilst AFM in force distance mode the strength of these. AFM was also utilised to visualize the absorbed molecules on the polymer surfaces. In Chapter 5 the area of gene therapy is introduced. It is hoped that in the future, gene therapy may form the basis of a cure for inherited gene tic diseases, such as hemophilia and other conditions such as AIDS and some cancers. The main problems which need to be overcome before this aim can be realised are firstly, isolating the correct genes to cure the diseases, and secondly, delivery of these genes. Cationic polymers and cationic lipids are two of the three main areas of research being investigated to find a potential carrier system for the DNA. In Chapter 5, the effect of PEG molecular weight on the condensation of plasmid DNA into a particles by poly(L-lysine)s for gene therapy is investigated. SPR was utilised to investigated the rate and extent of DNA binding and condensation by the various polymers, and utilising AFM the effect of PEG molecular weight on the structure of the observed particles was probed. The gene therapy theme is continued in Chapter 6 where the surface interactions of a cationic lipid / DNA gene therapy complex is investigated by both AFM and SPR. There are two main aims to the studies in this chapter. Firstly, to provide an understanding of the interactions between the DNA and lipid components of the delivery system. It is hoped this will supply further information on its stability, formation and structure and secondly, to provide a knowledge of the interactions of the complex with model surfaces. This may provide an insight into the gene therapy vectors possible mode of interaction with the cell. Chapter 7, is concerned with a family of dendrimeric polymers. The family of interest are the poly(amidoamine) (PAM AM) dendrimers. These have shown potential not only as drug delivery vehicles in the field of cancer chemotherapy and gene therapy, but also in enhancing medical imaging. The investigations performed in Chapter 7 form a basis for understanding the factors effecting the PAMAM's interaction with cell membranes and hence, provide information for optimising their formulation into drug delivery vehicles. The studies undertaken utilised both AFM and SPR as well as a range of model surface. These surfaces possess differing characteristics and were ulilised in conjunction with AFM and SPR to study the effect of dendrimer size, shape, surface charge and charge density on the interaction of these molecules. The final chapter, Chapter 8 discusses the progress made towards the aims of this thesis as outlined in section 1.8 and addresses the avenues for future investigations exposed by experimental work in chapters 3 - 7. Overall it is hoped that the work described in this thesis shows that a multi technique approach, as well as the collaborations of chemists, materials engineers, biophysicist, biologists and clinicians may, in the future lead to a better understanding of the materials utilised in the medical setting and hence provide a systematic design of systems for treating specific disease conditions.

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Schnabel, Julia Anne. "Multi-scale active shape description in medical imaging." Thesis, University College London (University of London), 1998. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.286180.

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Unsworth, Jennifer. "Novel porous scaffolds for tissue engineering cartilage." Thesis, University of Nottingham, 2004. http://eprints.nottingham.ac.uk/10187/.

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Damage to cartilage, caused either by disease or injury, affects a large number of people worldwide, severely reducing the patient's quality of life and generating a huge burden on healthcare systems. The limited success of treatment options such as tissue grafts has been the driving force behind much research into tissue engineering strategies for cartilage repair. One of the challenges associated with tissue engineering cartilage is that of generating constructs of clinically relevant sizes since the formation of a crust of tissue at the scaffold periphery restricts the supply of nutrients to the growing tissue. The hypothesis of this thesis was that a tissue engineering system incorporating scaffolds containing both random and anisotropic porosity and a novel flow perfusion bioreactor system would facilitate in vitro tissue formation by enhancing the supply of nutrients to the growing construct. This hypothesis was examined using cartilage as a model tissue. It was shown that scaffolds combining both random and anisotropic porosity (sparse knit scaffolds) had improved flow properties compared to scaffolds containing random porosity alone (needled felt scaffolds). Following studies to characterise the scaffolds and to determine the appropriate conditions for seeding cells into the scaffolds, cartilage formation within the different scaffolds was assessed over a four week culture period. It was found that the flow perfusion system was not as favourable for in vitro cartilage formation as either the commercially available Rotary Cell Culture System (RCCS) or static culture. One of the sparse knit scaffolds (sparse knit 4) and the needled felt were further compared for cartilage formation over an eight week culture period, using static and RCCS culture. With respect to collagen and glycosaminoglycan (GAG) production, cartilage constructs generated from the two scaffold systems were similar. Following static culture it was found that more viable cells were present at the centre of sparse knit 4 scaffolds than needled felt scaffolds. It was therefore concluded that scaffolds combining random and anisotropic porosity were advantageous for culturing tissues in environments where nutrient supply was reliant on diffusion alone.

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Mansouri, Sania. "Immunocamouflage of red blood cells by means of layer- by-layer self-assembly technique for medical transfusion." Thesis, McGill University, 2011. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=97073.

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Shortages in the blood supply have potential life-threatening consequences for patients requiring rapid and urgent blood transfusion. Different attempts described in the literature to produce universal blood have drawbacks and still induce the activation of the immune system. We report here new means of universal red blood cells (RBCs) production using the Layer-by-Layer (LbL) self-assembly technique for the deposition of chitosan-graft-phosphorylcholine (CH-PC), poly-L-lysine-graft-polyethylene glycol (PLL-PEG), hyaluronic acid (HA) and alginate (AL) onto functional and non-fixed RBCs. This idea was based on previous findings where fixed RBCs have been used as template for LbL multilayer assembly for the production of hollow capsules. The aim of this thesis, therefore, was to coat fresh and functional red blood cells (RBCs) with a multilayered polymeric shell.The natural polyelectrolytes, CH-PC, HA, PLL-PEG and AL were successfully assembled in a well-designed multilayer system on non-fixed RBCs in a two-dimensional (2-D) model through the electrostatic LbL assembly technique. A systematic study of constructs formed by two pairs of oppositely charged biocompatible polyelectrolytes has been performed. By modulating the film composition and build-up conditions, such as incorporating the protein-repulsive polyelectrolyte PLL-PEG, adjusting the film thickness and the multilayer permeability, cell recognition by the anti-A antibody is prevented. The main goal of this thesis was to develop a multilayer shell on non-fixed and functional RBCs in suspension. The design in suspension involved, CH-PC, PLL-PEG and AL that were successfully assembled in a nano-organized shell on non-fixed RBCs through the electrostatic LbL self-assembly technique. The RBCs' shape, morphology were not affected by the polyelectrolytes multilayers build-up. The multilayered nanoshell succeeded in preventing anti-A, anti-B, anti-Lewis y and anti-CD44 antibodies interactions with their specific antigens on the RBC membrane. Moreover, the RBCs maintained their initial role after their coating which is to carry oxygen. This research has demonstrated that LbL assembly of polyelectrolytes can be used as means to induce immunocamouflage of RBC antigens. As a preliminary step toward the clinical application of such universal red blood cells, an in vivo study was conducted to evaluate the safety and integrity of coated mice RBCs. The coated mice RBCs survived in bloodstream and did not trigger the immune system. These results represent a significant step toward the potential use of the coated RBCs as a universal blood in medical transfusion.
Les pénuries dans l'approvisionnement de sang ont des conséquences potentiellement mortelles pour les patients nécessitant une transfusion de sang rapide et urgente. Différentes tentatives de production de sang universel décrites dans la littérature présentent des inconvénients et induisent toujours l'activation du système immunitaire. Dans cette étude, nous rapportons une nouvelle stratégie de production de sang universel via la technique de déposition de couche par couche (CpC) de polymères tel que le chitosane-greffé-phosphorylcholine (CH-PC), la poly-L-lysine-greffé-polyéthylène glycol (PLL-PEG), l'acide hyaluronique (HA) et l'alginate (AL) sur les globules rouges (GR) fonctionnels et non-fixés. Cette idée est basée sur des résultats antérieurs, où les globules rouges ont été utilisés comme matrice pour l'auto-assemblage de multicouches pour la production de capsules creuses. L'objectif de cette thèse, était donc d'enrober des GR fonctionnels et non-fixés avec une multicouche polymérique.Les polyélectrolytes naturels, CH-PC, HA, PLL-PEG et AL ont été assemblés dans un système de multicouches sur les globules rouges non fixés dans un modèle deux-dimensions (2-D) via la technique d'assemblage électrostatique CpC. Une étude systématique des constructions formées par deux paires de polyélectrolytes biocompatibles de charges opposées a été effectuée. Par la modulation de la composition du film et les conditions de construction des CpC, telles que l'incorporation de PLL-PEG qui a la propriété de répulsion des protéines et en ajustant l'épaisseur du film et par conséquent la perméabilité de la multicouche, la reconnaissance par l'anticorps anti-A est empêchée.L'objectif principal de cette thèse était de développer une multicouche polymérique sur des GR non fixés et fonctionnels en suspension. Le design en suspension incluant CH-PC, PLL-PEG et AL qui ont été assemblés avec succès dans une multicouche nano-organisée sur des GR non fixés par la technique d'auto-assemblage électrostatique de CpC. La forme et la morphologie des GR n'ont pas été affectées par les multicouches de polymères. Les multicouches polymériques ont réussi à empêcher les anticorps anti-A, anti-B, anti-lewis y et anti-CD44 d'interagir avec leurs antigènes spécifiques à la surface des GR. De plus, les GR enrobés ont maintenu leur rôle initial de transporter l'oxygène. Cette recherche a démontré que l'assemblage de polyélectrolytes par la technique de CpC peut être utilisé comme un moyen d'induire l'immunocamouflage des antigènes érythrocytaires. Comme une étape préliminaire vers l'application clinique de ces GR universels, une étude in vivo a été réalisée pour évaluer la biocompatibilité et l'intégrité des GR de souris enrobés. Les GR enrobés ont survécu dans le sang et n'ont pas déclenché pas le système immunitaire chez la souris. Ces résultats représentent une étape importante vers l'application de ces GR universels en transfusion sanguine.

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Li, Kejia. "Custom biomedical sensors for application in wireless body area networks and medical device integration frameworks." Diss., Kansas State University, 2012. http://hdl.handle.net/2097/14632.

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Doctor of Philosophy
Department of Electrical & Computer Engineering
Steve Warren
The U.S. health care system is one of the most advanced and costly systems in the world. The health services supply/demand gap is being enlarged by the aging population coupled with shortages in the traditional health care workforce and new information technology workers. This will not change if the current medical system adheres to the traditional hospital-centered model. One promising solution is to incorporate patient-centered, point-of-care test systems that promote proactive and preventive care by utilizing technology advancements in sensors, devices, communication standards, engineering systems, and information infrastructures. Biomedical devices optimized for home and mobile health care environments will drive this transition. This dissertation documents research and development focused on biomedical device design for this purpose (including a wearable wireless pulse oximeter, motion sensor, and two-thumb electrocardiograph) and, more importantly, their interactions with other medical components, their supporting information infrastructures, and processing tools that illustrate the effectiveness of their data. The GumPack concept and prototype introduced in Chapter 2 addresses these aspects, as it is a sensor-laden device, a host for a local body area network (BAN), a portal to external integration frameworks, and a data processing platform. GumPack sensor-component design (Chapters 3 and 4) is oriented toward surface applications (e.g., touch and measure), an everyday-carry form factor, and reconfigurability. Onboard tagging technology (Chapters 5 and 6) enhances sensor functionality by providing, e.g., a signal quality index and confidence coefficient for itself and/or next-tier medical components (e.g., a hub). Sensor interaction and integration work includes applications based on the GumPack design (Chapters 7 through 9) and the Medical Device Coordination Framework (Chapters 10 through 12). A high-resolution, wireless BAN is presented in Chapter 8, followed by a new physiological use case for pulse wave velocity estimation in Chapter 9. The collaborative MDCF work is transitioned to a web-based Hospital Information Integration System (Chapter 11) by employing database, AJAX, and Java Servlet technology. Given the preceding sensor designs and the availability of information infrastructures like the MDCF, medical platform-oriented devices (Chapter 12) could be an innovative and efficient way to design medical devices for hospital and home health care applications.

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Bladen, John Stuart. "Imaging medical endoscopes in three dimensions using magnetic fields." Thesis, University of Sheffield, 1995. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.364248.

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Pye, Stephen Dominic. "Medical ultrasonics : adaptive time gain compensation in diagnostic imaging." Thesis, University of Edinburgh, 1987. http://hdl.handle.net/1842/29955.

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Cheikh, Al Ghanami Racha. "Novel thermoresponsive particle gels for tissue engineering applications." Thesis, University of Nottingham, 2011. http://eprints.nottingham.ac.uk/12318/.

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Biomaterials play an important role in tissue engineering, where they are used as scaffolds for the 3D culture of cells, to help the generation of neo tissues in-vitro and achieve superior tissue engraftment and regeneration in-vivo. The work presented in this thesis describes how thermoresponsive particle gels, a class of materials not previously investigated for tissue engineering applications, can find important applications in this field. The main gels developed and studied were the aqueous thermoresponsive particle gels prepared from poly(poly(ethylene glycol) methacrylate ethyl ether) (polyPEGMA246-EE) together with polycaprolactone (PCL) microparticles. The thermoresponsive polymer polyPEGMA246-EE, synthesised by free radical polymerisation, was employed as an adsorbing steric stabiliser for polycaprolactone microparticles prepared by the single emulsion solvent evaporation method. The resulting suspensions exhibited reversible temperature induced gelation based on incipient flocculation, where they switched from being free flowing at temperatures below 19°C to form space filling gels at body temperature (37°C) over periods of ~1 minute. On cooling, the suspensions returned to a fluid state. The viscoelastic properties of the particle gels could be controlled by varying the temperature and composition, enabling these gels to be tailored for specific applications. Using NIH3T3 as a model cell line, PCL/polyPEGMA246-EE particle gels exhibited key characteristics advantageous for the 3D culture of cells. These were mainly the ability to assemble around the cells at temperatures, above the LCST of polyPEGMA246-EE, and the provision of a supportive scaffold with appropriate mechanical properties for growth, along with good cytocompatibility enabling cell spreading and proliferation over extended culture times, as well as the rapid return to a flowable state on cooling allowing for suspension transfer, for cell subculture and harvesting, without the need for enzymes. The latter property would also allow for the injectable delivery of the in-vitro conditioned cell-gel constructs for therapeutic applications. Another variant of thermoresponsive particle gels has also been presented in this thesis. Thermoresponsive magnetic-particle gels were developed from the combination of magnetic polystyrene microparticles and the thermoresponsive polymer polyPEGMA246-EE. These exhibited reversible thermogelling behaviour which allowed for cell encapsulation, while their magnetic sensitivity allowed for cell recovery through simple magnetic particle separation. The novel concept of scaffold deconstruction by temperature, and cell recovery through magnetic-particles separation is significant for applications where a scaffold-free outcome would be desired such as the commercial expansion of therapeutic cells. In this thesis, the preparation and application of first generation biocompatible thermoresponsive particle gels is described. The combination of ease of preparation, the potential for scale-up and positive cell response make thermoresponsive particle gels promising as a new class of materials for applications in cell culture, as supports for tissue growth and in cell delivery systems. The materials developed and studied in this thesis are believed to represent a significant contribution to the fields of biomaterials, drug delivery and tissue engineering.

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Sidney, Laura E. "Tissue engineering in hostile environments : the effects and control of inflammation in bone tissue engineering." Thesis, University of Nottingham, 2013. http://eprints.nottingham.ac.uk/13499/.

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The potential effects of introducing bone regeneration strategies into environments of disease and damage are often overlooked, despite the fact that many of the signalling pathways in inflammation have effects on bone development and healing. Embryonic stem cells (ESCs) are increasingly being used to develop models of disease and have potential in osteogenic-cell based therapies. Osteogenic differentiation strategies for ESCs are well established, but the response of these cells to tissue damage and inflammation has not yet been investigated, particularly in comparison to primary osteoblasts. Here, proinflammatory cytokines were used as part of an in vitro model to mimic elements of skeletal disease, such as rheumatoid arthritis and non-union fractures. The response of osteogenically differentiated mouse embryonic stem cells (osteo-mESCs) to the proinflammatory cytokines interleukin 1-β (IL-1β), tumour necrosis factor-α (TNF-α) and interferon-γ (IFN-γ), was compared to that of primary mouse calvarial osteoblasts, already well-described in literature and used as a “benchmark” in this study. Although histology, immunocytochemistry and PCR showed similarities in osteogenic differentiation of the osteo-mESCs and the primary calvarial cells, over 21 days in culture, there were marked differences in the response to the proinflammatory cytokines. Viability of the osteo-mESCs was maintained in response to cytokines, whereas viability of primary cells was significantly reduced. There were marked increases in nitric oxide (NO) and prostaglandin E2 (PGE2) production in primary calvarial cells over the entire 21-day culture period, but this was not seen with osteo-mESCs until day 21. The study then went on to look at the effects of proinflammatory signalling on the in vitro bone formation of the two cell types. Significant differences in the effects of proinflammatory cytokines on bone nodule formation and matrix production were seen when comparing the osteo-mESCs and the calvarial cells. This study demonstrates that while osteo-mESCs share phenotypic characteristics with primary osteoblasts, there are some distinct differences in their biochemistry and response to cytokines. This is relevant to understanding differentiation of stem cells, developing in vitro models of disease, testing new drugs and developing cell therapies. An additional objective in this investigation was to look at tissue engineering strategies as a means of controlling inflammation in bone disease. The primary calvarial osteoblasts were utilised as an in vitro inflammation model, and used to study the effects of anti-inflammatory mediators. Anti-inflammatory-releasing porous scaffolds were manufactured from poly(lactic-co-glycolic acid) (PLGA) and poly(ethylene glycol) (PEG). The calvarial osteoblast inflammation model was used successfully to show successful release of diclofenac sodium from the PLGA/PEG scaffolds. This study demonstrates that there is much to consider in the development of regenerative strategies for bone disease, particularly the role that the effect and control of inflammation will play in bone healing.

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20

Singh, B. "Medical applications of mercuric iodide as a gamma ray detector." Thesis, Cardiff University, 1985. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.356730.

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21

Sawkins, Michael John. "Development of three-dimensional patterning strategies for osteochondral tissue engineering." Thesis, University of Nottingham, 2013. http://eprints.nottingham.ac.uk/12987/.

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Fully-realised three-dimensional patterning strategies enable the development of heterogeneous constructs which can recreate tissue architecture and cellular microenvironments over a large range of length scales. This in turn allows the development of more effective tissue models and tissue engineering therapies. The work presented in this thesis was designed to address the development of patterning methodologies and compatible biomaterial formulations. Poly(lactic-co-glycolic acid)-based (PLGA-based) microspheres were utilised for temporally-controlled protein delivery. Robust protocols were developed for the production of microspheres with two different mean sizes to provide distinct release kinetics which could be further tailored by the addition of a PLGA-poly(ethylene glycol)-PLGA (PLGA-PEG-PLGA) triblock copolymer. A semi-automated microinjection/micromanipulation (MM) system was used to precisely position individual microspheres into cell culture substrates. This approach has the potential to replicate complex interacting signal environments as seen in developmental and repair processes. Demineralised bovine bone, processed with or without a decellularisation step, was enzymatically digested to form solutions capable of gelation under physiological conditions. The resulting hydrogels outperformed collagen as in vitro culture substrates for bone-derived cells and are promising injectable scaffold materials. They were also formed into beads which could encapsulate exogenous proteins and which may be utilised in MM-based patterning strategies. Bioplotting was used to produce alginate hydrogel constructs containing highly viable cell populations. This technique was also used to deposit a PLGA-PEG microparticulate material which could be sintered under physiological conditions to achieve bone appropriate mechanical properties. PLGA-PEG/alginate dual material constructs could also be produced incorporating independent patterns of these two materials and of two cell populations and two protein signals. Bioplotting could therefore be used to produce sophisticated tissue engineering constructs for the repair of large, complex defects. Though this work focused on osteochondral applications much of the data is also more widely-applicable.

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Shi, Bibo. "Regularity-Guaranteed Transformation Estimation in Medical Image Registration." Ohio University / OhioLINK, 2011. http://rave.ohiolink.edu/etdc/view?acc_num=ohiou1312842132.

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23

Thomson, Ross John. "The psychosocial impact of home use medical devices." Thesis, University of Nottingham, 2017. http://eprints.nottingham.ac.uk/39768/.

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Recent increases in life expectancy, combined with the rise of chronic diseases, have led to a rise in the use of medical devices to monitor and treat illnesses in people’s homes. To date, however, little attention has been paid to understanding the impact that these devices have on the home environment, the users of these devices and their partners. This thesis presents three studies investigating the physical, personal and social issues faced by people using home medical devices. The first study consisted of qualitative interviews with 12 device users and seven partners and investigated their experiences of home use medical devices. Analysed thematically, this study described how medical devices can foster or threaten people’s experience of the physical, personal and social aspects of the home environment when medical devices are integrated into their homes. In study two, a questionnaire was developed to investigate the attitudes of healthcare professionals and patients about the relative importance of different medical device characteristics. Different groups of healthcare professionals involved with the provision of medical devices were included (doctors, nurses, pharmacists) as well as medical device users and non-users. The results showed that practical factors (user testing, clear instructions, clinical trials, reducing appointments, training and cost effectiveness) are viewed as more important by professional groups than factors that relate to the home environment (choice and appearance). This indicates a lack of a whole person approach to patient care and the selection of home medical devices. In the third study longitudinal interviews were carried out with four couples, where one of the couple had been diagnosed with Chronic Obstructive Pulmonary Disease (COPD) and prescribed an oxygen concentrator to use at home. The aim of this study was to discover how couples experience the process of being given a medical device to use at home over time. The interviews identified that being given an oxygen concentrator can be the source of an acute episode of uncertainty for some couples and the process of coping was mediated by the expectations that they had prior to being given the device. This research has provided a valuable insight into the poorly understood impact that medical devices have on people’s experience of the home environment.

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24

Majani, Ruby. "Gut construction : scaffolds for intestinal tissue engineering." Thesis, University of Nottingham, 2009. http://eprints.nottingham.ac.uk/29319/.

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Forming tissues in the laboratory to replace diseased or dysfunctional tissue or act as models for drug treatment is the goal of tissue engineering. The large intestine epithelium (colon surface) is a tissue which could benefit from both diseased and non-diseased models for the purpose of tackling colon cancer causes and treatments. Scaffolds (cell supports) are a pivotal part in many tissue engineering strategies. This thesis describes the design and production of two separate scaffolds based on the degradable polymer poly(lactic-co-glycolic acid) (PLGA). The first was a two dimensional scaffold to mimic the intestinal basement membrane which was modified with an oxygen plasma. The changes to the surface due to plasma and the degradation properties of the scaffold were extensively studied with SEM, XPS, AFM and GPC. The data showed that the oxygen plasma induced surface porosity and associated changes to surface roughness. The surface chemistry as detected by XPS was unchanged by both plasma treatment and degradation in buffered solution. The plasma treatment did lead to a dramatic loss in molecular weight but the degradation profile of both the untreated and etched films was similar. Extensive cell studies with SEM, live/dead, alamarBlue and Hoechst DNA assays showed that intestinal cells on the plasma treated scaffold was enhanced in terms of morphology, metabolic activity and proliferation. Finally, a two dimensional co-culture model using epithelial and myofibroblasts cell lines on the modified PLGA scaffold was achieved. The second scaffold was a three dimensional scaffold bearing the crypt like architecture of the colon. An accurate mould produced through electron beam lithography using dimensions measured from mouse histological sections. PLGA particles were used to fill the mould and sintered to produce the scaffold. A unique cell seeding approach using cell sheets was used. The cell sheets were produced on plasma polymers of acrylic acid and the discharge power was shown to affect surface wettability, chemistry and cell viability. The cell sheet approach proved to enhance cell attachment to the scaffold compared to individual cell seeding. Finally, a bilayer scaffold with model protein to mimic Wnt protein presence in the lower half of the crypt was studied with ToF-SIMS.

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25

Ginty, Patric J. "The supercritical processing of mammalian cells for applications in tissue engineering." Thesis, University of Nottingham, 2006. http://eprints.nottingham.ac.uk/11919/.

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Conventional methods of combining mammalian cells and synthetic polymers for tissue engineering applications are frequently problematic. This is due to the incompatibility between the sensitive cell component and the harsh polymer processing environments required to form the desired porous scaffold e. g. high temperatures and organic solvents. This results in the necessity for an often inefficient and time consuming two step scaffold seeding process, whereby mammalian cells are added to a pre-fabricated polymer scaffold. High pressure or supercritical CO2 (scCO2) processing is a method of fabricating porous polymer scaffolds at ambient temperatures and without using organic solvents. When pressurised, CO2 becomes highly soluble in a variety of amorphous polymers such as poly(DL-lactic acid) (PDLLA) to produce a high viscosity liquid. Subsequent decompression causes the formation of gas bubbles that become permanent as the polymer vitrifies. Based upon technology at the University of Nottingham, we hypothesised that mammalian cells could be incorporated into poly(DL-lactic acid) (PDLLA) scaffolds using a single step scCO2 process. This would not only make the process more rapid, but it would remove the inefficient scaffold seeding step required in most cell based tissue engineering strategies. Mammalian cells were subject to a range of high pressure CO2 and N2 processing conditions and assessed for cell survival. It was discovered that primary hepatocytes, meniscal fibrochondrocytes, myoblastic C2C12s and 3T3 fibroblasts could survive after exposure to both high pressure gases on a time and pressure dependent basis. Cells exposed to scCO2 for one minute were then assessed for both gene and enzyme function.Using a microarray, it was found that only eight genes (out of 9000) in murine C2C12 cells were significantly down-regulated when compared to untreated cells. Continued cell function was confirmed by measuring BMP-2 induced alkaline phosphatase activity as a measure of osteogenic differentiation in myoblastic C2C12 cells. Alkaline phosphatise activity was indistinguishable between untreated cells and cells exposed to scCO2 for one minute. Additional enzyme and receptor function was confirmed by measuring cytochrome P450 activity in primary hepatocytes after one minute of scCO2 processing. In the second half of the study, these short processing times were found to be sufficient to plasticise and foam porous PDLLA scaffolds. Therefore, cells were incorporated into the biodegradable PDLLA foams by pre-mixing the cell suspension with the polymer powder and exposing to scCO2. Subsequent decompression caused the polymer to foam with the cells trapped within the porous structure. Despite the presence of the plasticised PDLLA, cell survival was confirmed by both an Alamar B1ueTM assay and LIVE/DEADTM staining. Osteogenic differentiation on the scaffolds was confirmed by a stain and assay for BMP-2 induced alkaline phosphatase activity. Finally, a second generation processing piece of processing apparatus was designed that permitted mammalian cells to be passed into a pressurised vessel containing preplasticised PDLLA using a novel high-pressure CO2 injection system. This was made possible by constant optimisation of the high pressure apparatus and the introduction of a cell delivery valve. When injected at high pressures cell survival was found to be reduced when compared with previous experiments although this was likely to be due to the additional mechanical trauma caused by the injection process. Despite this, the live cell population was shown to retain its osteogenic differentiation capacity when induced with BMP-2. With further optimisation of the delivery method, cells may survive this process in sufficient numbers to suggest that it could be used as a method of seeding tissue engineering scaffolds in the future. This development could remove the limitations place on polymer processing time by the finite survival period of the cells, permitting tuning of the scaffold structure to suit the application. In summary, this study has demonstrated that mammalian cells can be incorporated into biodegradable PDLLA scaffolds using a rapid, one-step scCO2 process without the use of toxic solvents or elevated temperatures. Furthermore, the development of the high pressure injection system could allow cells to be incorporated during the fabrication step, removing the restrictions on polymer processing. This technique could be used for the rapid production of tissue cell loaded engineering scaffolds and other associated biotechnological applications where cells and synthetic polymers are combined, such as cell therapy and recombinant protein production.

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Quang, Tri T. "Development of Compact Multimodal Optical Imaging and Medical Assessment Systems." University of Akron / OhioLINK, 2015. http://rave.ohiolink.edu/etdc/view?acc_num=akron1452533192.

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27

Ahmed, Shehnaz. "Self-reporting scaffolds for in situ monitoring for regenerative medicine and tissue engineering applications." Thesis, University of Nottingham, 2018. http://eprints.nottingham.ac.uk/49511/.

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This thesis describes the development and utilisation of a self-reporting scaffold to improve current monitoring methods of the cellular microenvironment. In vitro tissue models hold a lot of promise for regenerative medicine and tissue engineering. However, many models lack the ability to non-invasively monitor in situ cellular responses in a physiologically relevant environment. By development of electrospun self-reporting scaffolds and incorporation of flow culture conditions, this limitation can be overcome. Electrospun matrices have been shown to mimic the structural architecture of the native extracellular matrix, whilst flow conditions have been shown to regulate cellular processes, and enhance mass transport and nutrient exchange throughout polymeric scaffolds. Here we show the development of optically transparent self-reporting electrospun scaffolds that incorporate ratiometric pH-sensitive nanosensors and respond to biological and mechanical cues of the native extracellular matrix through exposure to shear stress. Optically transparent self-reporting scaffolds were fabricated by directly electrospinning pH responsive, ratiometric nanosensors within a gelatin biopolymer matrix. The sensors consist of a porous polyacrylamide matrix which encapsulates pH-sensitive fluorophores that exhibit an additive fluorescent response across the full physiological range between pH 3-8, and a pH-insensitive reference fluorophore. The self-reporting scaffold was able to support cell growth whilst being able to simultaneously monitor local pH changes in real time. A Quasi-Vivo® bioreactor system was also used to generate a flow of cell culture medium and expose cell-seeded scaffolds to a continual shear stress. This novel diagnostic scaffold and the use of flow conditions can help simulate enhance the understanding of in vitro conditions, and generate advanced simulations in vivo to facilitate tissue engineering and regenerative medicine applications.

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Islam, Md Asiful. "Efficient Microwave Imaging Algorithms with On-Body Sensors for Real-Time Biomedical Detection and Monitoring." The Ohio State University, 2017. http://rave.ohiolink.edu/etdc/view?acc_num=osu1502906869993589.

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29

Salem, Aliasger K. "An injectable degradable porous polymer scaffold for tissue engineering and drug delivery." Thesis, University of Nottingham, 2002. http://eprints.nottingham.ac.uk/11918/.

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Cell transplantation on biodegradable scaffolds is an established approach in tissue engineering to the problem of the regeneration of diseased or damaged tissues. As cells grow and organise themselves, they secrete their own extracellular matrix, while the polymer degrades into natural metabolites resulting in eventual natural tissue replacement. Polymeric materials used for these scaffolds must satisfy a number of requirements. These include defined cell-interactive properties, porosity, biodegradability, mechanical and controlled release properties. To date, scaffolds have been designed to conform to these requirements. However, the need to perform defined three-dimensional structures requires prior knowledge of the dimensions of the defect or cavity to be filled. Furthermore the general use of toxic solvents in the processing of these scaffolds prevents the incorporation of biological agents and cells during fabrication. Therefore, poor transportation of cells through the scaffolds can result in low cell seeding efficiencies. Finally such scaffolds require an invasive operation for transplantation of the material. In contrast a number of injectable materials have been proposed and investigated. The transformation from liquid pre-cursor to gel in such systems can, however, require cell harmful trigger signals such as UV exposure or pH changes. Furthermore, these injectable gels lack a porous structure preventing effective cell migration and restricting tissue formation and vascularisation tothe barrier of diffusion for signalling and nutrient molecules. The work in this thesis presents a scaffold that is both injectable and conforms to the requirements of water-insoluble porous scaffolds. This starts with the synthesis of a biotinylated poly (lactic acid)-poly (ethylene glycol) (PLA-PEG) copolymer. The polymer is degradable, protein resistant and cell interactive when used in conjunction with biotinylated cell adhesive peptides. The biotin unit tethered to the PEG-PLA also provides the polymer with self-assembling properties when used in conjunction with avidin. In contrast to alternative injectable materials, the scaffold presented in this thesis is porous. This porosity is necessary for tissue ingrowth and vascularization. Therefore, before progressing on to the manufacture of the scaffold, a systematic study of two cell types involved in vascularisation was carried out over defined pore features. These studies revealed that cell behaviour over pore features was related to cell type, cell density and pore size. This had significant implications for the injectable scaffold in development because proposed advantages were delivery of a variety of cell types, controlled porous structure, and efficient cell seeding. Microparticles were then manufactured from the PLA-PEG-biotin using a single emulsion manufacturing process. Surface Plasmon Resonance (SPR) confirmed that these microparticles would bind efficiently to avidin. The condition for optimum self-assembling of particles was then determined using aggregation studies. These studies showed that a critical quantity of avidin was required for microparticles to aggregate together. The ability to aggregate particles of different sizes leads to the potential for controlling scaffold porosity. Rheological testing showed that the scaffold's mechanical properties could be tailored to that of the tissue in which regeneration is required. The self-assembly of microparticles was also demonstrated to form complex three-dimensional scaffolds without the use of toxic solvents. Scaffolds prepared in simulated tissues maintained shape upon injection. Scaffolds were then self-assembled with cells entrapped within them. Cell viability within the self-assembling scaffolds was confirmed by Alamar Blue assays. In vivo studies have demonstrated that cell-scaffold composites permit tissue ingrowth and thus readily undergo vascularisation. The novel molecular-interaction mechanism of self-assembly of these scaffolds differentiates this material from other injectable systems. The formation of porous scaffolds within a cavity or a soft-tissue could be a pre-requisite for tissue remodelling using new cell sources that are dependent on vascularisation and tissue ingrowth. The basic component of the scaffold is a biodegradable microparticle that presents a protein resistant surface with biotinylated moieties. Therefore, standard controlled release technologies and biotin-avidin mediated surface engineering can be combined with the self-assembly to form biomimetic scaffolds that stimulate integrin-mediated cell adhesion and then release growth factors.

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30

Delorme, Sebastien. "Biomechanical analysis of ankle kinematics and ligament strain in snowboarding." Thesis, University of Ottawa (Canada), 2004. http://hdl.handle.net/10393/29096.

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Because snowboarders are known to injure their ankles more often than alpine skiers, it has been postulated that stiffer snowboard boots would provide better protection to the ankle ligaments than current soft boots do. To test this hypothesis, we have measured the kinematics of the feet and lower legs of five snowboarders riding down a course of 10 gates on a ski hill using an electromagnetic motion tracking system. Results were obtained with each snowboarder wearing soft boots and stiffer step-in boots. The measurements were expressed in anatomically relevant rotations of the ankle joint complex. Two models were developed to predict ligament strains from rotations of the ankle joint complex: (1) a statistical model using published ligament strain measured on cadaver specimens at various combinations of ankle rotations as an interpolation and extrapolation table to predict strains in two ankle ligaments at the rotations measured during the snowboarding trials; (2) a personalized 2-degrees-of-freedom kinematic model of the ankle joint complex, based on the Denavit-Hartenberg formulation of serial-link manipulators, to predict strains in flue ankle ligaments from the relative position of the shank and foot. The experimental results showed that the left and right ankles are asymmetrically rotated, mostly in dorsiflexion, eversion and external rotation. Compared to step-in boots and bindings, soft boots and strap bindings allowed more rotation of the ankle joint complex and more strain in the anterior talofibular ligament, according to the statistical model. The kinematic model was not sensitive enough to detect differences in ligament strains between the 2 types of equipment. A functional determination of the axes of rotation of the talocrural and subtalar joints could further improve the predictions of this model. This is the first known study to document experimentally the kinematics of snowboarding. It generally confirms the expectation that softer boats allow significantly wider ranges of ankle rotation and ligament strain.

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Zhang, Jing 1961. "System identification of bladder hydrodynamics." Thesis, McGill University, 1994. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=26440.

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Understanding bladder mechanics and the changes caused by bladder outlet obstruction is an important task in urology. In this work, bladder mechanics are examined in terms of bladder hydrodynamics: the relation between a perturbing volume applied to the bladder and the evoked pressure change. A PC-based experimental system was built which can generate a computer-controlled perturbation volume and measure volume and pressure signals.
The bladders of six minipigs, three normal and three obstructed, were subjected to stochastic volume perturbations about different average volume levels and evoked pressure changes were measured. The hydrodynamic stiffness transfer function relating volume and pressure was calculated and described by a second-order, lumped parametric model having inertial, viscous and elastic terms. Estimates of the elastic constant (K) increased linearly with volume in both normal and obstructed animals. The rate of increase was substantially greater in the obstructed animals than in the normals. Consequently, this approach shows promise for distinguishing normal and obstructed bladder mechanics.

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Veerassamy, Shalini. "Revisiting hemodynamic analysis of pulmonary edema after the onset of left ventricular dysfunction using a mathematical model of the cardiovascular system." Thesis, McGill University, 2000. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=31075.

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The aim of this project was to extend a mathematical model of the cardiovascular circulation, originally built by Burkhoff and Tyberg [6]. The model was implemented in Simulink and consists of 6 lumped vascular compartments interconnected by segments allowing unidirectional blood flow. A set of 6 differential equations describe changes in blood volume in the four systemic and two ventricular compartments as functions of time in terms of the pressure across each compartment and the resistances between them. The model was used to investigate why pulmonary venous pressure rises after the onset of left ventricular dysfunction. Special attention was given to the pericardial and peripheral resistance effects. Sensitivity analysis showed that our parameter values and ratios were more appropriate than those of Burkhoff and Tyberg [6]. We conclude that, although stressed volume has a fundamental role in raising the pulmonary venous pressure, contractile strength and systemic arterial resistance also contribute considerably.

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Galiana, Laura. "Identification of ankle stiffness components in stroke patients." Thesis, McGill University, 2002. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=79230.

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The purpose of this study was to measure ankle stiffness in stroke patients using system identification, which provides an objective method of separating reflex and intrinsic stiffness components.
We studied twelve (12) stroke patients with clinical evidence of ankle spasticity and compared them with nine (9) gender- and age-matched controls. Subjects lay supine with their foot attached to an electro-hydraulic actuator by a custom-fitted boot. Series of pseudo-random binary sequences were used to rotate the ankle. The position, torque, and EMG recorded during these perturbations were used to separate the reflex and intrinsic contributions of ankle stiffness.
The results of this study showed that ankle stiffness was increased in four (4) stroke patients, mostly due to the increased reflex stiffness component. Furthermore, the changes in reflex stiffness varied with position; ankle stiffness increased in these stroke subjects as the ankle was dorsiflexed. The reflex gain parameter explained the increased reflex stiffness.

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Hauerstock, David. "Telemetric measurement of compressive loads in the sheep lumbar spine." Thesis, McGill University, 2000. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=30785.

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The goal of this study was to develop and validate a system for the telemetric measurement of in vivo compressive intervertebral loads in the sheep, and to measure these loads in a variety of activities.
A miniature load cell and radio transmitter were implanted in the L3--L4 space of the spine. A total of four sheep were operated on; one was sacrificed five days after surgery, due to failure of the transmitter, and another was sacrificed after failing to ambulate for two weeks after surgery. The other two animals (average mass 67 kg) were kept for five weeks, during which a range of activities were performed, including standing, lying prone, walking/trotting, and jumping.
Results for a range of activities were as follows: in walking at 1.5 m/s, average maximum and minimum loads were 461 N and 256 N, respectively; in walking at 2m/s, average maximum and minimum loads were 684 N and 303 N, respectively; in standing, loads averaged 161 N; and in lying prone, loads averaged 212 N. The highest loads were recorded in jumping, where the peak load was 1290 N.
The results of this study demonstrate for the first time, to our knowledge, the magnitude of in vivo axial loads in the sheep lumbar spine. These findings have implications for the evaluation of studies which employ the sheep model to test spinal implants. As treatment methods for disc degeneration progress from the spacer and fusion approach to more sophisticated prostheses and tissue engineered disc replacements which preserve segmental mobility, such data will become even more important to the design, animal testing, and evaluation of implants.

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Shen, Litao. "Diffusion tensor imaging application." Thesis, Purdue University, 2015. http://pqdtopen.proquest.com/#viewpdf?dispub=1602902.

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Central nervous system (CNS) related conditions and diseases like mild traumatic brain injury (mTBI) and multiple sclerosis (MS) affect people’s life quality, yet there is no single test for the diagnosis of these diseases or conditions. Patients may need to wait for years until they are diagnosed correctly to get the correct treatment, which is often too late. Thus, there is a strong need to develop some techniques to aid the diagnosis of CNS-related conditions and diseases. The conventional MRI can reveal the structure of the brain but cannot detect the difference between the healthy tissue and the anomalies. Diffusion tensor imaging (DTI) has been used for detecting white matter integrity and demyelination for the past decade in experiments and has been proven to have the ability to depict the problem effectively. In the past decade, many techniques were found based on DTI data, and these techniques improved pre-processing, processing, and post-processing.

Though there are many software and APIs that can provide functions for DTI file input/output (IO), visualization and other DTI related topics, there is no general software or API that is dedicated to covering the whole processing procedure of DTI that at the same time can be extended easily by the user. This thesis is dedicated to developing a software that can be used to aid in the diagnosis of CNS-related conditions and diseases while at the same time trying to cover as many topics as possible. Another purpose is to make the software highly extensible.

This thesis work first introduces the background of CNS-related disease and uses MS as an example to introduce the process of demyelination and the white matter integrity problem, which are involved in these CNS-related diseases and conditions. Then the diffusion process and the technique that can detect the diffusion signal (DTI) is presented. After this, concepts and meaning of the secondary metrics are discussed. Then, current existing software and APIs and their advantages and disadvantages are outlined. After these points, the techniques that are discussed in this thesis as well as their advantages are outlined. This part is followed by the charts and code samples which can illustrate the process and structure of this software. Then different modules and their results are explained.

In this software, the results are represented by images and 3D models. There are color images, pseudo color images with different schemes and gray scale images. Images are mainly included to represent the FA and MD data. In this software, streamlines are generated from the eigenvalue and eigenvector. Then a bundled result for the streamline is also realized in this software. The streamline and bundled results are 3D models. For 3D models, there are mainly two ways to display the real 3D model. One is the naked eye 3D which doesn’t require the user to wear glasses but has less stereoscopic characteristics. As the stereoscopic monitors and glasses are more and more popular and easily accessible, this software also provides stereoscopic views for 3D models, and the user can choose red & blue, interlaced techniques with proper glasses.

This thesis work ends with the discussion of the results and limitations of DTI. Finally, there is a discussion about the future work that can improve the performance of this software and topics that need to be covered.

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Lakhotia, Kritika. "Visualization and quantification of 3D tumor-host interface architecture reconstructed from digital histopathology slides." Thesis, State University of New York at Buffalo, 2016. http://pqdtopen.proquest.com/#viewpdf?dispub=10127616.

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Oral cavity cancer (OCC) is a type of cancer of the lip, tongue, salivary glands and other sites in the mouth (buccal or oral cavity) and is the sixth leading cause of cancer worldwide. Patients with OCC are treated based on a staging system: low-stage patients typically receive less aggressive therapy compared to high-stage patients. Unfortunately, low-stage patients are sometimes at risk for locoregional recurrence. Recently, a semi-quantitative risk scoring system has been developed to assess the locoregional recurrence risk for low-stage patients. This risk scoring system is based on tissue characteristics determined on 2D histopathology images under a microscope. This modality limits the appreciation of the 3D architecture of the tumor and its associated morphological features. This thesis aims to visualize 3D models of the tumor-host interface reconstructed from serially-sectioned histopathology slides and quantify their clinically validated morphological features to predict locoregional recurrence after treatment. The 3D models are developed and quantified for 6 patient cases using readily available tools. This pilot study provides a framework for an automated diagnostic technique for 3D visualization and morphological analysis of tumor biology which is traditionally done using 2D analysis.

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Thompson, Carla M. "The Utility of Patient-Specific CT Dose Estimation Maps." Cleveland State University / OhioLINK, 2015. http://rave.ohiolink.edu/etdc/view?acc_num=csu1440534502.

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Huang, Jiwei. "Multispectral Imaging of Skin Oxygenation." The Ohio State University, 2012. http://rave.ohiolink.edu/etdc/view?acc_num=osu1356637098.

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Perring, Steve. "Clinical applications of the three dimensional (3D) analysis and visualisation of medical slice images." Thesis, University of Southampton, 1992. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.387074.

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He, Jianyi. "THE COMMERCIAL IMPACT ON BUSINESS MODELS OF MEDICAL IMAGING SOLUTIONS THROUGH DATA-ANALYTICAL METHODOLOGIES." Case Western Reserve University School of Graduate Studies / OhioLINK, 2021. http://rave.ohiolink.edu/etdc/view?acc_num=case1620233525109266.

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Wadkins, David Allen. "Nanoparticles: nanoscale systems for medical applications." Thesis, University of Iowa, 2017. https://ir.uiowa.edu/etd/6008.

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The goal of this project was to develop a series of nano platforms for single cell analysis and drug delivery. Nanoparticles are a promising option to improve our medical therapies by controlling biodistribution and pharmacokinetics of therapeutics. Nanosystems also offer significant opportunity to improve current imaging modalities. The systems developed during this thesis work can be foundations for developing advanced therapies for obesity and improving our fundamental understandings of single cell behavior. The first of the two systems we attempt to create was a drug delivery system that could selectively target adipose tissue to deliver uncoupling agents and drive browning of adipose tissue and associated weight loss. Protonophores have a history of significant toxic side effects in cardiac and neuronal tissues a recently discovered protonophore, but BAM-15, has been shown to have reduced cytotoxicity. We hypothesized that the altered biodistribution of BAM-15 encapsulated in a nanoparticle could provide systemic weight loss with minimized side effects. The second system developed utilized quantum dots to create a fluorescent barcode that could be repeatedly identified using quantitative fluorescent emission readings. This platform would allow for the tracking of individual cells, allowing repeat interrogation across time and space in complex multicellular environments. Ultimately this work demonstrates the process and complexity involved in developing nanoparticulate systems meant to interact with incredibly complex intracellular environments.

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Paik, Isha. "Development of an in vitro pump : mechanical characterization and surface engineering of elastomeric membranes." Thesis, University of Nottingham, 2013. http://eprints.nottingham.ac.uk/28237/.

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In vitro modelling offers the potential of recapitulating human degenerate tissue for physiological studies and pharmacological screening. Yet, few systems have been developed to date, primarily due to the lack of vascularisation in engineered tissue. Here, the development of an in vitro pump is addressed. This will be the first component of a long term strategy to build internal circulatory systems for in vitro engineered tissue. Firstly, mechanical characterisation and surface biocompatibility of spin coated poly(dimethylsiloxane) (PDMS) elastomeric membranes was investigated to assess whether PDMS could be used as a structural constituent. Results showed that spin coating speed defines both film thickness and specific mechanical properties since tensile testing revealed that PDMS membranes exhibit thickness-dependent mechanical properties. Plasma polymerisation of allylamine was used to surface engineer the hydrophobic PDMS surface to promote cell adhesion and proliferation. Surface characterisation revealed that PDMS surfaces became hydrophilic and nitrogen enriched as a result of plasma polymerised allylamine (ppAAm) deposition. Additionally, a thick ppAAm deposition (92 nm) is required to minimise hydrophobic recovery of PDMS. Cell culture studies showed that cells readily attached to ppAAm (92 nm) deposited PDMS and that these surfaces were best suited to cultivating cells compared to other surface treatments. Secondly, a method was developed to control cell positioning on the PDMS surface, since cell alignment is required to generate directional and contractile force. The deposition of ppAAm (92 nm) and airbrushing of extracellular matrix (ECM) aerosols can be spatially restricted using a micro-stencil. Individual and multiple cell line patterns were achieved that remained faithful for ≤ 10 days. Importantly, this technique micropatterned cells at high resolution over macro scales. External mechanical stimulation was used to influence cell alignment and cytoskeletal organisation on ppAAm (92 nm)/ Fibronectln (Fn) micropatterned PDMS. Results showed that incorporating substrate strain with surface micropatterning can be used to control site- and alignment- specific cell attachment.

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Hidalgo-Bastida, Lilia Araida. "Development of a novel porous scaffold : assessment of its suitability for cardiac muscle engineering." Thesis, University of Nottingham, 2008. http://eprints.nottingham.ac.uk/29087/.

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Cellular transplantation, a current therapy for cardiac failure, does not consider the need for a physical support or biochemical factors required by the cardiomyocyte. The aim of this project was to establish the Extra Cellular Matrix (ECM), architectural and mechanical properties of a flexible scaffold to assist the maintenance of a cardiac cell line cultured under mechanical stimuli. Previously, mechanical stimulation has been proved to have an effect in cardiomyocytes similar to that of growth factors on other cells and promotes protein expression, differentiation and survival [1]. Poly-(1,8-octanediol-co-citric acid) [POC] is an elastomer that can be processed into scaffolds for tissue engineering. Mechanical properties of the POC were compared at different porosity, storage method and strain rate. POC, with an ultimate elongation of 60-160%, did support cardiac cell attachment when coated with fibronectin. Seeding strategies were evaluated to find optimal conditions and static seeding resulted more favourable for cell adhesion and survival than other dynamics approaches. In collaboration with the University of Leeds, cardiomyocytes were cultured in a dynamic bioreactor, Tencell, under continuous and discontinuous stretching regimes. Mechano-stimulation of cardiac constructs encouraged cell survival in the discontinuous regime and up-regulated the expression of actc1 and nppa genes regardless of the treatments. It was concluded that although mechanical stimulation had a positive effect on cell survival and gene expression, tissue formation was not promoted.

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Kim, Wan. "Study of parallel MR imaging techniques." Thesis, State University of New York at Buffalo, 2015. http://pqdtopen.proquest.com/#viewpdf?dispub=1594739.

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In MRI, it is more desirable to scan less data as possible because it reduces MRI scanning time. We want to get a clear image by reconstructing the signals we acquire from the MRI machine. Special scanning or sampling techniques are needed to overcome this issue based on various mathematical methods.

We present an improved random sampling pattern for SAKE (simultaneous autocalibrating and k-space estimation) reconstruction and an iterative GRAPPA reconstruction using Wiener filter.

In our iterative method using Wiener filter, in contrast to the conventional GRAPPA where only the auto calibration signals (ACS) are used to find the convolution weights, our proposed method iteratively updates the convolution weights using both the acquired and reconstructed data from previous iterations in the entire k-space. To avoid error propagation, the method applies adaptive Wiener filter on the reconstructed data. Experimental results demonstrate that even with a smaller number of ACS lines the proposed method improves the SNR when compared to GRAPPA.

In compressed sensing MRI, it is very important to design sampling pattern for random sampling. For example, SAKE (simultaneous auto-calibrating and k-space estimation) is a parallel MRI reconstruction method using random undersampling. It formulates image reconstruction as a structured low-rank matrix completion problem. Variable density (VD) Poisson discs are typically adopted for 2D random sampling. The basic concept of Poisson disc generation is to guarantee samples are neither too close to nor too far away from each other. However, it is difficult to meet such a condition especially in the high density region. Therefore the sampling becomes inefficient. In this paper, we present an improved random sampling pattern for SAKE reconstruction. The pattern is generated based on a conflict cost with a probability model. The conflict cost measures how many dense samples already assigned are around a target location, while the probability model adopts the generalized Gaussian distribution which includes uniform and Gaussian-like distributions as special cases. Our method preferentially assigns a sample to a k-space location with the least conflict cost on the circle of the highest probability. To evaluate the effectiveness of the proposed random pattern, we compare the performance of SAKEs using both VD Poisson discs and the proposed pattern. Experimental results for brain data show that the proposed pattern yields lower normalized mean square error (NMSE) than VD Poisson discs.

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Haemer, Gillian. "Optimizing Radio Frequency Coil Performance for Parallel Magnetic Resonance Imaging at Ultra High Field| Evaluation and Optimization of Integrated High Permittivity Materials." Thesis, New York University, 2018. http://pqdtopen.proquest.com/#viewpdf?dispub=10751718.

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In the time since magnetic resonance imaging (MRI) was introduced, scientific progress has allowed for a factor-of-ten increase in static magnetic (B₀) field strength, and has developed MR into a clinical workhorse. This increase in B₀ field strength has the potential to provide significant gains to the inherent signal-to-noise ratio of resulting images. However, this progress has been limited by degradations in the spatial homogeneity of the radiofrequency magnetic fields used for nuclear excitation (B₁), which have wavelengths comparable to the dimensions of the human body in modern high-field MRI. Techniques to improve homogeneity, including B₁-shimming and parallel transmission, require multi-element radiofrequency (RF) transmit arrays. Increasing B₀ field strength is also associated with an increase in the deposition of RF energy into the subject, clinically measured and regulated as Specific energy Absorption Rate (SAR), deposited in tissue during image acquisition. High permittivity materials (HPMs) have the potential to augment RF coil performance outside of B₁-shimming or parallel transmission methods. The use of HPM pads placed in existing RF coils has also been shown to provide a potential reduction of array SAR in nuclear excitation, as well as potential performance benefits in signal reception. However, the question of how best to strategically use these materials in the space between the coil and the sample in order to maximize benefit and alleviate any potential problems has not yet been thoroughly addressed.

The contributions presented in this dissertation demonstrate the potential utility of the integration of HPMs into transmit-receive RF coils, as an integral component of the hardware design. A framework to quickly choose the relative permittivities of integrated materials, optimized relative to an absolute standard (rather than relative to a different design) is introduced, and used to demonstrate that readily available material properties can provide significant improvements in multi-element transmit performance. A subsequent analysis of practical effects and limitations of these materials on the RF coil resonance properties is performed, including the description of a unique adverse resonance splitting phenomenon and how to avoid it. A transmit/receive RF coil design is built and evaluated, first on its own experimentally, and then in simulation with a helmet-shaped high permittivity material former to examine the benefits and challenges associated with HPM integration into RF coils.

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Gordon, Kerry. "Modelling and monitoring of medical time series." Thesis, University of Nottingham, 1986. http://eprints.nottingham.ac.uk/12369/.

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In this thesis we examine several extensions to the dynamic linear model framework, outlined by Harrison and Stevens (1976), in order to adapt these models for use in the on-line analysis of medical time series that arise from routine clinical settings. The situation with which we are most concerned is that where we are monitoring individual patients and wish to detect abrupt changes in the patient's condition as soon as possible. A detailed background to the study and application of dynamic linear models is given, and other techniques for time series monitoring are also discussed when appropriate. We present a selection of specific models that we feel may prove to be of practical use in the modelling and monitoring of medical time series, and we illustrate how these models may be utilized in order to distinguish between a variety of alternative changepoint-types. The sensitivity of these models to the specification of prior information is examined in detail. The medical background to the time series examined requires the development of models and techniques enabling us to analyze generally unequally-spaced time series. We test the performance of the resulting models and techniques using simulated data. We then attempt to build a framework for bivariate time series modelling, allowing, once more, for the possibility of unequally spaced data. In particular, we suggest mechanisms whereby causality and feedback may be introduced into such models. Finally, we report on several applications of this methodology to actual medical time series arising in various contexts including kidney and bone-marrow transplantation and foetal heart monitoring.

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Young, Melissa Denton. "Arterial Calcification and the Clinical Implications on Stent Function." Case Western Reserve University School of Graduate Studies / OhioLINK, 2013. http://rave.ohiolink.edu/etdc/view?acc_num=case1364999090.

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Lewandowski, Mark E. "The Design, Fabrication, and Evaluation of Mobile Point-of-Care Systems for Cellular Imaging in Microfluidic Channels." Case Western Reserve University School of Graduate Studies / OhioLINK, 2018. http://rave.ohiolink.edu/etdc/view?acc_num=case1512576064493513.

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Lee, Zhi Hou. "Improved multiple input multiple output blind equalization algorithms for medical implant communication." Thesis, University of Nottingham, 2015. http://eprints.nottingham.ac.uk/28726/.

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Medical implant sensor that is used to monitor the human physiology signals is helpful to improve the quality of life and prevent severe result from the chronic diseases. In order to achieve this, the wireless implant communication link that delivers the monitored signal to a multiple antennas external device is an essential portion. However, the existing conventional narrow band Medical Implant Communications System (MICS) has low data rate because of the bandlimited channel is allocated. To improve the data rate in the radio frequency communication, ultra-wide band technology has been proposed. However, the ultra-wide band technology is relatively new and requires living human to be the test subject in order to validate the technology performance. In this condition, the test on the new technology can rise ethical challenge. As a solution, we improve the data rate in the conventional narrow band MICS. The improvement of data rate on the narrow band implies the information bandwidth is larger than the allocated channel bandwidth, and therefore the high frequency components of the information can loss. In this case, the signal suffers the intersymbol-interference (ISI). Instead of that, the multiple antennas external device can receive the signal from other transmitting implant sensor which has the same operating frequency. As a result, the signal is further hampered by co-channel interference (CCI). To recover the signal from the ISI and CCI, multiple-input multiple output (MIMO) blind equalization that has source separation ability can be exploited. Cross-Correlation Constant Modulus Algorithm (CC-CMA) is the conventional MIMO blind equalization algorithm that can suppress ISI and CCI and able to perform source separation. However, CC-CMA has only been analyzed and simulated in the modulation of Phase Shift Keying (PSK). The performance of CC-CMA in multi-modulus modulation scheme such as 4-Pulse-amplitude modulation (PAM) and 16-Quadrature amplitude modulation (QAM), which has higher data rate than PSK, has not been analyzed. Therefore, our work is to analysis and optimize CC-CMA on the multi-modulus modulation scheme. From our analysis, we found that the cost function of CC-CMA is biased cost function. Instead of that, from our simulation, CC-CMA introduces an unexpected shrinking effect whereby the amplitudes of the equalizer outputs have been reduced, especially in multi-modulus modulation scheme. This shrinking effect is not severe in PSK because the decision of a PSK symbol is based on phase, but not amplitude. Unfortunately, this is severe in multi-modulus modulation scheme. To overcome this shrinking effect in multi-modulus modulation scheme, we propose Cross-Independent Constant Modulus Algorithm (CI-CMA). Based on the convergence analysis, we identify the new optimum dispersion value and mixing parameter in CI-CMA. From the simulation results, we confirm that CI-CMA is able to perform equalization and source separation in the multi-modulus modulation scheme. In order to improve the steady state performance of CI-CMA, we perform the steady state mean square error (MSE) analysis of CI-CMA using the energy preservation theorem that was developed by Mai and Sayed in 2001, and our result is more accurate than the previous work. From our analysis, only the reduction in adaptation step size can reduce the steady state MSE, but it is well known that the MSE is indeed a tradeoff with the speed of convergence. Therefore without sacrificing convergence speed, our last effort is to propose hybrid algorithms. The hybrid algorithms are done by combining a new adaptive constant modulus algorithm (ACMA), a decision directed algorithm and a cross-correlation function. From the simulation results, we found that the hybrid algorithms can show low steady state error and thereby improve the reliability of the communication link. The main achievement of this thesis is the discovery of new dispersion value through the convergence analysis.

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Warrick, Philip A. "A VRML-based anatomical visualization tool for medical education." Thesis, National Library of Canada = Bibliothèque nationale du Canada, 1997. http://www.collectionscanada.ca/obj/s4/f2/dsk2/ftp01/MQ29635.pdf.

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Dissertations / Theses on the topic 'Medical and biomedical engineering'

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