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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
51

Ultrasonic imaging of the structure and elasticity of the carotid bifurcation

Jackson, Joel R. 05 1900 (has links)
No description available.
52

A fluid mechanic assessment of the total cavopulmonary connection

Ensley, Ann Elizabeth 05 1900 (has links)
No description available.
53

Blood flow evaluation using an intracoronary doppler catheter

Newton, Bradley Scot 05 1900 (has links)
No description available.
54

Hemodynamic wall shear stress in models of atherosclerotic plaques using phase contrast magnetic resonance velocimetry and computational fluid dynamics

Karolyi, Daniel Roberts 05 1900 (has links)
No description available.
55

The prevalence of preclinical atherosclerosis in a healthy adult population

Griffith, Garett J. 03 May 2014 (has links)
Cardiovascular disease (CVD) is a progressive disease that presents signs, such as abnormal thickening or stiffening of arteries, early in its preclinical stage, and screening tools such as carotid intima media thickness (CIMT) measurement and pulse wave velocity (PWV) assessment have the potential to identify individuals prior to the clinical manifestation of CVD. The purpose of this study was to determine the prevalence of preclinical atherosclerosis, as indicated by high CIMT and PWV values, in an adult population aged 40-70 years and free of diagnosed CVD using these screening tools. Secondarily, this study aimed to compare established CVD risk factors and other health parameters between those with elevated or normal arterial health values. Sixty subjects made 2 visits to the Ball State University Human Performance Laboratory. The first visit included basic anthropometric measurements as well as assessment of CIMT and PWV. After a one week objective physical activity assessment, subjects returned to the HPL for assessment of blood lipids and body composition via dual energy x-ray absorptiometry scan. Prevalence of preclinical atherosclerosis was calculated from the total sample as well as within both genders, and an independent samples t-test was conducted in order to identify significant differences in health characteristics between those in the normal and high groups. Abnormal CIMT or PWV values were present in 43% of study subjects; 30% and 18% of the test sample met the criteria for elevated CIMT and PWV, respectively. Significant differences existed between normal and high CIMT and PWV study groups for physical activity, body composition, and blood lipid profile variables. Comparisons within each gender revealed differences in health profile elements. Both the CIMT and PWV measurement techniques may be valuable additions for community CVD screenings, as certain health profile abnormalities may impact each marker of arterial health differently. Additional research is needed in order to determine the cost-effectiveness of these screening tools as a preventive health method. / School of Physical Education, Sport, and Exercise Science
56

Measurements of Turbulence at High Reynolds Numbers / From Eulerian Statistics Towards Lagrangian Particle Tracking

Küchler, Christian 25 March 2021 (has links)
No description available.
57

Measurement of air flow at vacuum conditions using small Venturis

Alonso, Hector January 1980 (has links)
Small Venturis were used to measure air flow rates through cigarette-making machines to a vacuum header. A programmable calculator was used to develop charts for each Venturi. showing flow versus differential pressure at inlet vacuums from 8 in. (203 mm) to 20 in. (508 mm) of mercury. Use of the charts eliminates the need to calculate the flow each time a test is run. An error analysis indicated that large variations in temperature do not affect the result. The accuracy of the charts is not affected as long as the tests are run at room temperature. The Venturis, ranging in size from ½ in. (13 mm) to l ½ in. (38 mm) will continue to be used to measure and monitor vacuum requirements of the machines. / Master of Engineering
58

Measurement of blood flow through proton activation of positron emitting tracers

Miller, Thomas James January 1981 (has links)
Thesis (M.S.)--Massachusetts Institute of Technology, Dept. of Nuclear Engineering, 1981. / MICROFICHE COPY AVAILABLE IN ARCHIVES AND SCIENCE. / Bibliography: leaf 186. / by Thomas James Miller, Jr. / M.S.
59

Probing the circumgalactic medium through optical spectrography and future near-ultraviolet detector development

Cruvinel Santiago, Bárbara January 2023 (has links)
The circumgalactic medium (CGM), loosely defined as the region between a galaxy disk and its virial radius, has long been of interest to astronomers and astrophysicists because it acts as an interface between galaxies and their surroundings. Studying it, therefore, gives us hints of how gas flows between galaxies and the intergalactic medium (IGM), fueling star formation for instance. This thesis addresses some of the current and future observation, analysis and instrumentation challenges that should be tackled for a better understanding of the CGM. Chapter 1 is an overview of science related to the CGM and of instruments that our lab works on: the Circumgalactic Hydrogen-Alpha Spectrograph (CHaS) and the Faint Intergalactic-medium Redshifted Emission Balloon (FIREBall). It sets the ground for a better understanding of the science discussed in subsequent chapters. CHaS is an IFU spectrograph installed on a 2.4 m telescope at the MDM Observatory in Arizona (Melso et al. 2022). It has high sensitivity and high spectral resolution, and it collects individual spectra from points across our targets using a microlens array, allowing us to make detailed spectral maps of observed astronomical objects. FIREBall is a balloon-born UV multi-object spectrograph, allowing us to look at yet another emission line prominent in the CGM. In this thesis, we will focus on what a future FIREBall detector might look like. Chapters 2 and 3 present data collected with CHaS in November 2021 from two very distinct objects: NGC 6946 (the Fireworks galaxy) and M76 (the Little Dumbbell nebula). Both chapters address how we process spectral data from CHaS images and the subsequent making of velocity maps. Using CHaS images, we tackle anomalous gas motion and formations in both targets. We compared the data presented in both chapters to previous literature, showing that CHaS velocity maps were more detailed and complimented previous findings. NGC 6946 is known for being a prolific star forming galaxy and also for having holes in its HI distribution, which have historically been attributed to the expansion and bursting of gas bubbles. In Chapter 2, we find that the motion around these holes is indeed consistent with expanding bubbles and galactic fountains on their edges, with velocities in the -20 km/s to 20 km/s range, consistent with what Boomsma et al. (2008) found, going up to +/-60 km/s, similar to the velocities found by Efremov et al. (2002). We also found that Long et al. (2019)'s supernova remnants candidates catalog had a clear position correlation with the boundaries of different holes in the Boomsma et al. (2008) HI hole catalog, suggesting that these holes might indeed be related to gas bubbles resulting from supernova explosions. The Little Dumbbell nebula, on the other hand, show its own set of anomalies. M76 is a butterfly planetary nebula with a central torus and two polar lobes. We find that these lobes are not completely symmetric. In fact, the wester lobe is more rounded and the eastern one is more stretched and fragmented. From our velocity maps, we propose a couple of explanations for how the ISM might interact with the nebula both in the core star's AGB phase and after the nebula is formed to give M76 its shape. Both explanations vary depending on the assumed direction of motion of the star in it its AGB phase, but both are consistent with models by Villaver, Manchado and García-Segura (2012) and Wareing et al. (2007). Moreover, we compare our data to those of other authors and find similar velocity ranges around an axis going from one lobe to another as spectral maps made by Ramos-Larios et al. (2017) and Bryce et al. (1996). Departing from observational data analysis, Chapter 4 focuses on how we can probe further into the CGM by upgrading existing instruments, turning commonplace condensed matter methods into tools for astrophysics. More specifically, Chapter 4 discusses the possibility of switching FIREBall's current UV sensitive emCCD detectors, which rely on coating to be visible-blind and on cryogenic equipment that is heavy for a balloon flight, for devices made out of hexagonal boron nitride (hBN). hBN's main energy bandgap overlaps with the emission lines that FIREBall is interested in capturing, and it can be combined with graphene (which is isomorphic to hBN) to make high quality, quantum efficient devices. While we weren't able to finish full devices, Chapter 4 discusses their fabrication in detail as well as how our Siesta SISL simulations show that even small device defects might be acceptable for a detector. The chapter ends with considerations about how one might fit individual devices as multi-pixel detectors.
60

Quantitative and continuous measurement of cerebral blood flow by a thermal method

Wei, Datong January 1993 (has links)
No description available.

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