Introduction: Functional motility disorders of the colon are poorly defined. Hence, patients with chronic colonic motor dysfunction are treated or undergo surgery without proper diagnosis. Most colonic motility assessment centers around the largest propagating motor pattern in the colon- the High Amplitude Propagating Pressure Wave (HAPW). However, there is no consensus regarding a definition of this important motor pattern. Additionally, no consideration is given to other aspects of colonic motility such as colo-ano-rectal coordination and control by the autonomic nervous system (ANS). The aim of this thesis was to improve understanding of HAPWs and other features of colonic motility in health and constipation, understand how autonomic dysfunction is related to observations in patients, and evaluate the effect of neuromodulation of the ANS. Methods: Motility was assessed in healthy volunteers and patients using water-perfused High Resolution Colonic Manometry (HRCM). To assess the association between ANS and colonic motor activity Heart Rate Variability (HRV) was measured in patients. Spatiotemporal maps were created using HRCM to analyse and quantify colonic motor activity following baseline, and interventions which included proximal balloon distention, meal, and rectal bisacodyl. Low-Level Light Therapy (LLLT) was also applied during HRCM as a method of neuromodulation, to observe its effect on colonic motility. Results: Normal HAPWs are those which have an amplitude of more than 50 mmHg and belong to one of 3 categories: proximally originating, proximal continuing, and transverse/descending. The best intervention sequence to generate these during HRCM assessment is baseline, proximal balloon distention, meal, rectal bisacodyl. Based on their responses to these interventions and the type of HAPWs present, patients could be classified into strong responder, weak responder and non-responder groups. Overall, patients in the strong responder group were most similar to healthy volunteers both with regard to motility and ANS control. Conversely, the weak and non-responders had showed decreased or no motility with decreased parasympathetic input and occasionally sympathetic inhibition. Additionally, other features of motility such as the sphincter of O'Beirne, and lack of colo-ano-rectal coordination were found to lead to constipation even in presence of normal HAPWs. LLLT shows promise in initiating colonic motor activity through neuromodulation of the sacral defecation center. Conclusions: HAPWs can be defined into one of three categories and used to categorize patients based on their HAPW response to different interventions. However, other aspects of colonic motility such as the colo-ano-rectal coordination and autonomic nervous system control of colonic motility should be taken into consideration in diagnosis of constipation, as they can point towards more non-invasive treatment methods such as neuromodulation using LLLT. / Thesis / Master of Science in Medical Sciences (MSMS)

The theme of this dissertation is to advance safety hazard mitigation by detecting and characterizing hidden targets of concern. Ground-penetrating radar (GPR) is used to detect and characterize hidden targets that pose safety hazards at Earth's surface, within shallow soil, and within rock. The resulting images detect unexploded ordnance (UXO) and detect fractures that pose collapse hazards in a mine. Detecting and characterizing fractures and voids within rock prior to excavation can enable mitigation of mine collapse hazards. GPR data were acquired on the wall of a pillar in an underground mine. Strong radar reflections in the field data correlate with fractures and a cave exposed on the pillar walls. Pillar wall roughness was included in migration, a wavefield imaging algorithm, to quantitatively locate fractures and voids and map their spatial relationships within the rock. Quantifying the radar reflection amplitudes enabled mapping the distance between fracture walls. Detecting and characterizing UXO and landmines from a safe distance can enable de-mining. Migration was used to improve GPR imaging for unmanned aerial vehicle (UAV) data acquisitions. Existing algorithms were adapted for UAV flight irregularities and surface topography, and a new algorithm was developed that does not depend on the unknown soil wavespeed. Errors associated with wavespeed and raypath assumptions were quantified. The algorithms were tested with real and synthetic datasets. The improved and new algorithms are more successful than previous algorithms. To detect linear targets at all orientations, fully polarized GPR data are needed. Polarity combinations were investigated to optimize the detection of surface and subsurface small targets and linear targets. Scattering caused by topographic roughness is the primary shallow subsurface noise. For subsurface targets, detection is optimized by migration plus a polarity combination that captures all scattered energy. Strong reflection and scattering from the air-ground boundary can hide surface targets. Detection is optimized by removing the strong isotropic surface scattering, imaging targets by their anisotropic scattering. / Doctor of Philosophy / The theme of this dissertation is to advance safety hazard mitigation by detecting and characterizing hidden targets of concern. Ground-penetrating radar (GPR) is used to detect and characterize hidden targets that pose safety hazards at Earth's surface, within shallow soil, and within rock. The resulting images detect unexploded ordnance (UXO)/landmines and detect fractures that pose collapse hazards in a mine. Detecting and characterizing fractures and voids within rock prior to mining can enable mitigation of mine collapse hazards. GPR data were acquired on the wall of a pillar in an underground mine. Strong radar reflections in the field data correlate with fractures and a cave exposed on the pillar walls. Pillar wall roughness was included in migration, a wavefield imaging algorithm, to quantitatively locate fractures and voids and map their spatial relationships within the rock. Quantifying the radar reflection amplitudes enabled mapping the distance between fracture walls. Detecting and characterizing UXO, landmines from a safe distance can enable de-mining. Migration was used to improve GPR imaging for an unmanned aerial vehicle (drone) data acquisition. Existing algorithms were adapted for drone flight irregularities and surface topography, and a new algorithm was developed that does not depend on the unknown soil properties. Errors associated with the algorithms' assumptions were quantified. The algorithms were tested with real and computer-generated datasets. The improved and new algorithms are more successful than previous algorithms. To detect all targets regardless of their orientation, GPR data need to be acquired with antenna pointing in multiple directions (different polarities). Polarity combinations were investigated to optimize the detection of surface and subsurface small targets and linear targets. Scattering caused by topographic roughness is the primary shallow subsurface noise. For subsurface targets, detection is optimized by migration plus a polarity combination that captures all scattered energy. Strong radar reflection from the air-ground boundary can hide surface targets. Detection is optimized by removing the strong ground surface from the data, and imaging targets by differences in their radar scattering.

Ablation controlled electrothermal (ET) plasma discharge devices consist of a small diameter capillary through which a large amount of energy is discharged. The high energy in the discharge ablates an inner sleeve material, ionizes the material, and a high energy-density plasma jet accelerates out the open end. ET devices can find applications in internal combustion engines, Tokamak fusion fueling and stabilization, hypervelocity launchers, and propulsion. The ballistic properties of an ET device are highly dependent on the propellant and ablated material. A useful noninvasive technique to characterize a propellant in these types of devices is spectroscopy. The purpose of this study is to design and conduct experiments on the ET facility called PIPE to verify results and assumptions in the ETFLOW simulation code as well as resolve data collection issues such as equipment triggering as spectrometer saturation. Experiments are carried out using an Ocean Optics LIBS2500plus high resolution spectrometer and a Photron FASTCAM SA4 high speed camera. Electron plasma temperatures are estimated using copper peaks in the UV region with the relative line intensity method, and electron plasma density is estimated by measuring the full width at half maximum (FWHM) of the stark broadened H--β line at 486 nm. Electron temperatures between 0.19 eV and 0.49 eV, and electron densities between 4.68*1022 m-3 and 5.75*10²² m⁻³ were measured in the expanding plasma jet about an inch outside the source with values as expected for this region. Velocity measurements of PIPE match well with simulations at around 5333 m/s. This study concluded that the assumption that the propellant Lexan is completely dissociated is a valid assumption, and that the ETFLOW results for electron temperature, density, and bulk plasma velocity match experimental values. / Master of Science

No description available.

<p>Heteroepitaxial SiGeC layers have attracted immenseattention as a material for high frequency devices duringrecent years. The unique properties of integrating carbon inSiGe are the additional freedom for strain and bandgapengineering as well as allowing more aggressive device designdue to the potential for increased thermal budget duringprocessing. This work presents different issues on epitaxialgrowth, defect density, dopant incorporation and electricalproperties of SiGeC epitaxial layers, intended for variousdevice applications.</p><p>Non-selective and selective epitaxial growth of Si_1-x-yGe_xC_y(0≤x≤30, ≤y≤0.02) layershave been optimized by using high-resolution x-ray reciprocallattice mapping. The incorporation of carbon into the SiGematrix was shown to be strongly sensitive to the growthparameters. As a consequence, a much smaller epitaxial processwindow compared to SiGe epitaxy was obtained. Differentsolutions to decrease the substrate pattern dependency (loadingeffect) of SiGeC growth have also been proposed. The key pointin these methods is based on reduction of surface migration ofthe adsorbed species on the oxide. In non-selective epitaxy,this was achieved by introducing a thin silicon polycrystallineseed layer on the oxide. The thickness of this seed layer had acrucial role on both the global and local loading effect, andon the epitaxial quality. Meanwhile, in selective epitaxy,polycrystalline stripes introduced around the oxide openingsact as migration barriers and reduce the loading effecteffectively. Chemical mechanical polishing (CMP) was performedto remove the polycrystalline stripes on the oxide.</p><p>Incorporation and electrical properties of boron-doped Si_1-x-yGe_xC_ylayers (x=0.23 and 0.28 with y=0 and 0.005) with aboron concentration in the range of 3x10¹⁸-1x10²¹atoms/cm3 have also been investigated. In SiGeClayers, the active boron concentration was obtained from thestrain compensation. It was also found that the boron atomshave a tendency to locate at substitutional sites morepreferentially compared to carbon. These findings led to anestimation of the Hall scattering factor of the SiGeC layers,which showed good agreement with theoretical calculations.</p><p><b>Keywords:</b>Silicon germanium carbon (SiGeC), Epitaxy,Chemical vapor deposition (CVD), Loading effect, Highresolution x-ray diffraction (HRXRD), Hall measurements, Atomicforce microscopy (AFM).</p>

With the advances in the computing world, computational fluid dynamics (CFD) is becoming more and more critical tool in the field of fluid dynamics. In the past few decades, a huge number of CFD models have been developed with ever improved performance. In this research a robust CFD model, called Riemann2D, is extended to model flow over a mobile bed and applied to a full scale dam break problem. Riemann2D, an object oriented hyperbolic solver that solves shallow water equations with an unstructured triangular mesh and using high resolution shock capturing methods, provides a generic framework for the solution of hyperbolic problems. The object-oriented design of Riemann2D has the flexibility to apply the model to any type of hyperbolic problem with the addition of new information and inheriting the common components from the generic part of the model. In a part of this work, this feature of Riemann2D is exploited to enhance the model capabilities to compute flow over mobile beds. This is achieved by incorporating the two dimensional version of the one dimensional non-capacity model for erodible bed hydraulics by Cao et al. (2004). A few novel and simple algorithms are included, to track the wet/dry and dry/wet fronts over abruptly varying topography and stabilize the solution while using high resolution shock capturing methods. The negative depths computed from the surface gradient by the limiters are algebraically adjusted to ensure depth positivity. The friction term contribution in the source term, that creates unphysical values near the wet/dry fronts, are resolved by the introduction of a limiting value for the friction term. The model is validated using an extensive variety of tests both on fixed and mobile beds. The results are compared with the analytical, numerical and experimental results available in the literature. The model is also tested against the actual field data of 1957 Malpasset dam break. Finally, the model is applied to simulate dam break flow of Warsak Dam in Pakistan. Remotely sensed topographic data of Warsak dam is used to improve the accuracy of the solution. The study reveals from the thorough testing and application of the model that the simulated results are in close agreement with the available analytical, numerical and experimental results. The high resolution shock capturing methods give far better results than the traditional numerical schemes. It is also concluded that the object oriented CFD model is very easy to adapt and extend without changing the generic part of the model.

Au cours des dernières années, l’essor spectaculaire des microsystèmes (ou MEMS), qui touche tous les domaines industriels, est à l’origine de nombreux et nouveaux progrès technologiques. Néanmoins, dans ce contexte prometteur de large envergure, la fiabilité des MEMS s’avère être la problématique à améliorer pour franchir la phase d’industrialisation à grande échelle. C’est dans le cadre de cette thématique de fiabilité des microsystèmes, que s’inscrit ce travail.La température étant un paramètre majeur entrant dans de nombreux mécanismes d’endommagement des MEMS, notre étude présente la conception et la réalisation d’un banc de thermographie infrarouge de haute résolution (2 µm), associé à la mise en œuvre d’une méthodologie d’analyse et de traitement des mesures infrarouges.Ce dispositif innovant permet un diagnostic in-situ, sans contact et rapide des défaillances des MEMS par mesures locales et quantitatives des pertes thermiques associées. Cet outil constitue une avancée importante pour détecter, mesurer et comprendre les mécanismes d’endommagement des MEMS. Il nous permet de reconstituer des images thermiques de tout type de microsystème en cours de fonctionnement ou soumis à des tests de vieillissement accéléré, et ceci afin de réaliser une analyse fine et rapide de leur fiabilité.Ce travail apporte de nouveaux résultats en ce qui concerne la détection des mécanismes de défaillance de différents types de MEMS-RF et tout particulièrement des MEMS-RF avec contact électrique. / Over the last few years, considerable effort has gone into the study of the failure mechanisms and reliability of MicroElectroMechanical Systems (MEMS). MEMS performance and reliability are affected by many parameters, such as the complex physical interactions between thermo-mechanical deformation, current flow, high power actuation and contact heating. In particular, temperature is a key issue for the design of a low loss and reliable MEMS. In order to improve device reliability it is essential to understand the thermal behaviours of RF-MEMS under standard or harsh current conditions. In this work, we present a new approach to investigate the failure mechanism of MEMS. An original set-up has been developed to localise and measure the heat loss of MEMS during actuation. Thermal characterization has been performed using infrared thermography to investigate the thermal sensitivity of MEMS. A brand new infrared bench was developed for temperature distribution measurement. An infrared camera, operating in the 1,5 - 5 µm bandwidth, was coupled to a new specific optic to reach an enhanced spatial resolution better than 2 µm/pixel. This work presents several results obtained on different advanced RF-MEMS including RF-MEMS switches where failure mechanism had been diagnosed.

The Keck Planet Imager and Characterizer (KPIC) is a cost-effective upgrade path to the W.M. Keck observatory (WMKO) adaptive optics (AO) system, building on the lessons learned from first and second-generation extreme AO (ExA0) coronagraphs. KPIC will explore new scientific niches in exoplanet science, while maturing critical technologies and systems for future ground-based (TMT, FELT, GMT) and space-based planet imagers (HabEx, LUVOIR). The advent of fast low-noise IR cameras (IR-APD, MKIDS, electron injectors), the rapid maturing of efficient wavefront sensing (WFS) techniques (Pyramid, Zernike), small inner working angle (IWA) coronagraphs (e.g., vortex) and associated low-order wavefront sensors (LOWFS), as well as recent breakthroughs in high contrast high resolution spectroscopy, open new direct exoplanet exploration avenues that are complementary to planet imagers such as VLT-SPHERE and the Gemini Planet Imager (GPI). For instance, the search and detailed characterization of planetary systems on solar-system scales around late-type stars, mostly beyond SPHERE and GPI's reaches, can be initiated now at WMKO.

This thesis studies the monohydrate, dihydrate and in some cases, trihydrate of five carboxylic acids, namely acetic acid, propanoic acid, T-difluoroacetic acid, Gdifluoroacetic acid and trifluoacetic acid using the technique of Fourier tranform microwave spectroscopy. The rotational and centrifugal distortion constants of these hydrates were determined with high accuracy. Ab initio calculations were also performed to locate the different conformational minima of the hydrates and to optimize their structures. Comparison of the ab initio predicted rotational and centrifugal distortion constants with the experimentally observed values allows us to determine the structures of the global minimum conformations of the various hydrates without ambiguity. Hydrogen-bonded ring structures are found to be the predominant feature in all observed hydrates. In this structural arrangement, all the hydrogen bonds formed are located in the same ring, and the cooperativity effect between them significantly strengthens each hydrogen bond, as suggested by the sharp increase of their binding energies in the larger hydrates. The fine and hyperfine splittings observed in the specrum were also successfully analyzed, which allows information on the dynamics of the intramolecular large amplitude tunnelling motions to be extracted explicitly. In the final part of this thesis, the equilibrium constants for the formation of monohydrates of the different carboxylic acids involved in this thesis, together with that of formic acid whose microwave spectrum has been analyzed elsewhere, were calculated to approximately derive their abundances under typical atmospheric conditions. It was found that about 2% of FMA, ACA and PPA will complex with one H2O molecule to form monohydrates in the low troposphere, while for TFA, the value increases to about 15%, mainly as a result of the larger binding energy of TFA–(H2O) due to fluorination on the end group.

Reduced-activation ferritic steels are considered as the primary candidate materials for structural applications within nuclear fusion power plants. It is known that by mechanically alloying ferritic steel powder with Y (usually in the form of Y₂O₃) then consolidating the material by hot isostatic pressing, a nanoscale dispersion of oxygen rich nanoclusters as small as ~2nm is introduced into the microstructure. This vastly improves high temperature strength and creep resistance, and the nanoclusters also act as trapping sites for helium and point defects produced under irradiation. In this thesis, the evolution of the oxide nanoclusters in a Fe-14Cr-2W-0.3Ti & 0.3Y₂O₃ ODS alloy was investigated primarily using atom probe tomography. The microstructure was characterised at various points during processing to give an insight into the factors influencing the formation of the nanoclusters. It was found that the nanoclusters nucleated during the mechanical alloying stage, then followed near classical nucleation and growth mechanisms keeping the same composition of ~8%Y, ~12%Ti,~25%O and ~45%Cr throughout. The formation and evolution of 5-15nm grain boundary oxides was also observed, and these were shown to form first as Cr₂O₃ particles that subsequently transform into a Y-Ti-O based oxide on further processing. The influence of mechanical alloying with 0.5wt.%Fe₂Y rather than 0.3wt.%Y₂O₃ was also investigated, and this showed that there was no difference in the final microstructure produced provided the level of Ti in the starting powder was tightly controlled. Without sufficient Ti, the nanoclusters were Y-O based and ~6nm diameter. Both the Y-O and Y-Ti-O nanoclusters were moderately stable on annealing at 1200°C for up to 100 hours, with only minimal coarsening observed. Ti was found not to influence the coarsening rate of the nanoclusters significantly. The stability of the oxide nanoclusters under irradiation was investigated by using Fe²⁺ ion irradiation to simulate displacement cascade damage in the ODS-Eurofer material (the official European candidate material for testing in the ITER fusion test reactor). Doses up to ~6 dpa at 400°C were used, and there was no significant change to the nanocluster distribution. However segregation of Mn to dislocations was observed after irradiation. These results indicate that ODS steels are good candidate structural materials, as the microstructure is stable at high temperature and under irradiation. The starting powders, and processing parameters need to be tightly controlled in order to produce the optimal material for use in service.