Global ETD Search
Search theses and dissertations gathered from participating repositories worldwide. Every result links back to the library that holds it. No account is needed.
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Showing 1 to 20 of 35 for “"phase contrast imaging"”.
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X-ray phase contrast imaging of preclinical atherosclerosis
… biochemical profile, followed by angiographic imaging. However, patients with subclinical atherosclerotic disease can also be at high risk for ACS. In fact, nearly half of the patients suffer from sudden cardiac death without any prior indication of atherosclerotic disease. For these patients, …
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Compact tomographic X-ray phase-contrast imaging of breast cancer
Non-invasive imaging plays an important role throughout the clinical diagnosis and management process of breast cancer. Unfortunately, existing imaging methods lack the combination of spatial resolution and soft-tissue contrast necessary to visualize pathological changes in the breast. X-ray …
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Capabilities and limitations of Phase Contrast Imaging techniques with X-rays and neutrons
Phase Contrast Imaging (PCI) was studied with the goal of understanding its relevance and its requirements. Current literature does not provide insight on the effect of a relaxation in coherence requirements on the PCI capabilities of an imaging system. This problem is all the more important since …
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An experimental study of turbulence by phase-contrast imaging in the DIII-D takamak
Thesis (Ph. D.)--Massachusetts Institute of Technology, Dept. of Physics, 1997.
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Phase contrast imaging measurements and modeling of short wavelength turbulence in the DIII-D tokamak
The DIII-D phase contrast imaging (PCI) diagnostic has been upgraded and used to measure turbulence in the outer plasma region (0.7 < r/a < 1). These upgrades extended its operational range to high frequencies (10 kHz - 10 MHz), short wavelength (2 - 30 cm-1), and improved the signal-to-noise ratio …
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A study of reversed shear Alfvén eigenmodes in Alcator C-Mod with phase contrast imaging
… shear equilibria during the current ramp-up phase and sawtoothing phase are studied through the spatial and temporal characteristics of the RSAEs. Analysis of the spatial structures of RSAEs measured by phase contrast imaging, and interpreted with a synthetic diagnostic using numerical …
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A Novel Method to Assess Pulse Wave Velocity using Single Velocity Encoding in Phase Contrast Imaging
… of pulse wave velocity (PWV) using conventional phase contrast magnetic resonance imaging (PC-MRI) is recognized as a standard technique to assess arterial stiffness by measuring the arrival times of blood velocity waveforms. Conventional PC-MRI requires the acquisition of two sets of complex …
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A combined phase contrast imaging and heterodyne interferometer system for multiscale fluctuation measurements on DIII-D
… a heterodyne interferometer to the pre-existing phase contrast imaging (PCI) system, both of which measure line-integrated electron-density fluctuations. The port-space footprint is minimized by using a single 10.6 pm CO2 laser and a single beampath. With temporal bandwidths in excess of 1 MHz, …
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Studies of ICRF mode conversion with phase contrast imaging and full-wave simulations in Alcator C-Mod
… codes be validated against experiment. The phase contrast imaging (PCI) technique has been used on Alcator C-Mod to measure directly the rf waves. The measurements were compared to predictions of full-wave simulations using a synthetic diagnostic method. The measured mode converted wave …
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Developing a Microbubble-based Contrast Agent for X-ray Phase Contrast Imaging to Detect Neovasculature in Breast Cancer
X-ray phase contrast imaging (XPC) generates contrast from refraction and scattering of X-rays, unlike absorption in conventional radiology. This technique greatly improves the sharpness of boundaries and reveals micro-structured tissues that are not easily detected by conventional absorption-based …
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Turbulence and transport studies with phase contrast imaging in the Alcator C-Mod tokamak and comparisons with gyrokinetic simulations
An upgraded phase contrast imaging (PCI) diagnostic is used to study turbulence and transport in Alcator C-Mod. The upgraded PCI system is capable of measuring density fluctuations with high temporal (2 kHz-5 MHz) and wavenumber (0.5-55 cm-1) resolution. An upgrade of the system has enabled PCI to …
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Ultracold Fermi gas with repulsive interactions
… with a mean-field model for the ferromagnetic phase transition. However, later research showed the absence of enhanced spin fluctuation, which is definitive evidence against the ferromagnetic phase transition. Still, our work triggered a lot of research on repulsive interactions in ultracold …
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Investigation of alternative jet fuels in gas turbine combustion systems using x-ray radiography
… to conventional jet fuel. In this work, x-ray phase-contrast imaging is performed at 90,517 Hz on a combusting fuel spray in a realistic gas turbine combustor, allowing characterization of breakup process of fuel into ligaments and then individual droplets as it leaves a nozzle. This imaging is …
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Two-Color interferometry as a fluctuation diagnostic on Alcator C-Mod
… local oscillator using high bandwidth analog in-phase/quadrature electronics, replacing lower bandwidth digital fringe counting electronics. The raw outputs of the high bandwidth electronics, which are proportional to the sine and cosine of the interferometric phase shift, are digitized at up to …
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Impact of alternative jet fuels on gas turbine combustion systems
… droplet distributions at this condition, a 2D phase Doppler anemometer (PDA) is used to characterize alternative jet fuels’ sprays and compare them to the Jet-A fuel spray in a realistic single-cup swirl-stabilized ‘referee’ combustor, under the umbrella of the Aviation Sustainability Center’s …
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Techniques for Reducing Beam-Induced Damage in Electron Microscopy
Imaging biomolecules in their natural state at an atomic scale resolution is crucial to the un- derstanding of such molecules. Under the banner of Quantum Electron Microscopy (QEM), two novel electron microscopy schemes have been proposed to achieve nanometer-scale resolution while practically …
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Digital Rock: Understanding the mechanism of Enhanced Oil Recovery (EOR) Core Floods
… lower than 10 ft d-1 using Magnetic Resonance Imaging (MRI). For that reason, an optimisation toolbox, which uses the relaxation times and the diffusion coefficients of the porous system as input and derives the optimum experimental parameters for the MRI sequence, was developed. The novel MRI …
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Experimental application and numerical study of reflectometry in the Alcator C-Mod tokamak
… reflectometry is similar to that measured by the phase contrast imaging system. Simulations also indicate that plasma curvature extends the reflectometry response to fluctuations of high poloidal wavenumber. A preliminary study indicates that reflectometry can be used to estimate the correlation …
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Patterns of Hemolymph Pressure Related to Tracheal Tube Collapse in the Beetle Pterostichus commutabulis
… prothorax while simultaneously using synchrotron phase contrast imaging to observe morphological changes in the trachea. We observed that a pressure pulse co-occurred with every tube compression observed throughout the body, suggesting that pulses in hemolymph pressure are responsible for tracheal …
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Analysis of a Proposed Cell Binding Site on Caenorhabditis Elegans Collagen Type Iv
… the homozygous null phenotype. Nomarski and phase contrast imaging indicate that CBS mutants exhibit a worse morphological phenotype than homozygous null mutants. Immunocytochemical techniques were used to analyze physical defects of body wall muscle structure and function in animals with the …
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