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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.
11

Mitral valve replacement complicated by iatrogenic left ventricular outflow obstruction and paravalvular leak: case report and review of literature

Lee, Justin Z., Tey, Kai R., Mizyed, Ahmad, Hennemeyer, Charles T., Janardhanan, Rajesh, Lotun, Kapildeo January 2015 (has links)
BACKGROUND: Left ventricular outflow tract (LVOT) obstruction and paravalvular leak (PVL) are relatively uncommon, but are serious complications of prosthetic valve replacement. CASE PRESENTATION: We present a case that displays the unique therapeutic challenges of treating a patient who developed both LVOT obstruction and mitral PVL after undergoing surgical aortic and mitral valve replacement (MVR). We also describe the use of alcohol septal ablation and albumin-glutaraldehyde (BioGlue) for septal ablation to percutaneously treat the patient's LVOT obstruction, followed by use of an Amplatzer vascular plug for percutaneous closure of an antero-medial mitral PVL associated with severe regurgitation. CONCLUSION: Percutaneous interventional management of these entities may be considered as an initial therapeutic option, especially in high-risk patients with significant morbidity and mortality of repeat surgical operations.
12

A Model to Measure Lymphatic Drainage from the Eye

Kim, Min Hui 12 December 2011 (has links)
Intraocular pressure (IOP) is the most important risk factor for glaucoma development and progression. Most anti-glaucoma treatments aim to lower IOP by enhancing aqueous humor drainage from the eye. Aqueous humor drainage occurs via well-characterized trabecular meshwork (TM) and uveoscleral (UVS) pathways, and the recently described ciliary lymphatics. The relative contribution of the lymphatic pathway to aqueous drainage is not known. We developed a sheep model to quantitatively assess lymphatic drainage along with TM and UVS outflows. Following intracameral injection of 125I-bovine serum albumin (BSA), lymph and blood samples were continuously collected. Lymphatic and TM drainage were quantitatively assessed by measuring 125I-BSA recovery. This quantitative sheep model enables assessment of relative contributions of lymphatic drainage (1.64% ± 0.89%), TM (68.86% ± 9.27%) and UVS outflows (19.87% ± 5.59%), and may help to better understand the effects of glaucoma agents on outflow pathways.
13

A Model to Measure Lymphatic Drainage from the Eye

Kim, Min Hui 12 December 2011 (has links)
Intraocular pressure (IOP) is the most important risk factor for glaucoma development and progression. Most anti-glaucoma treatments aim to lower IOP by enhancing aqueous humor drainage from the eye. Aqueous humor drainage occurs via well-characterized trabecular meshwork (TM) and uveoscleral (UVS) pathways, and the recently described ciliary lymphatics. The relative contribution of the lymphatic pathway to aqueous drainage is not known. We developed a sheep model to quantitatively assess lymphatic drainage along with TM and UVS outflows. Following intracameral injection of 125I-bovine serum albumin (BSA), lymph and blood samples were continuously collected. Lymphatic and TM drainage were quantitatively assessed by measuring 125I-BSA recovery. This quantitative sheep model enables assessment of relative contributions of lymphatic drainage (1.64% ± 0.89%), TM (68.86% ± 9.27%) and UVS outflows (19.87% ± 5.59%), and may help to better understand the effects of glaucoma agents on outflow pathways.
14

Research on Searching and Positioning of Buried Underwater Pipelines

Hsiao, Po-yuan 03 February 2005 (has links)
In recent years, ocean has become a place to dispose of industrial and civil waste waters. Hence, there are more and more projects to establish offshore outflow pipes. These underwater pipes should be kept monitored in order to maintain their functions specifically. The purpose of this research was to explore the two outflow pipes in Kaohsiung offshore area, i.e., Chung-chou outflow pipe and Tso-ying outflow pipe, by using an integrated surveying system which includes a side-scan sonar and a sub-bottom profiler. The ultimate objective was to investigate the feasibility of this system in searching and positioning of buried underwater pipelines. Based on this investigation, the offshore section of Chung-chou outflow pipe is about 2.8km in length and extends offshore to the direction of 38o from the west to the south. The water depth at the end of this pipe is about 21m. Among the 2.24km section initiated at the offshore end of the pipe, the buried depths are between 2.2m and 3.2m. There are two disposed gravel zones around the offshore end of the pipe. The first zone is about 130m in length and 10m wide. The second zone is 220m in length and 20m wide. Moreover, based on the side scan sonar images, there are 71 protective concrete blocks located around Chung-chou outflow pipe. The offshore section of Tsao-ying outflow pipe is about 4.76 km in length and extends to the direction of 20o from the west to the south. The water depth at the end of this pipe is about 17m. Among the 3.7km section initiated at the offshore end of the pipe, the buried depths are about 1.0 to 2.5m. A disposed gravel zone with dimensions of 330m in length and 10m wide is located at the end of this pipe. In addition, there are 43 protective blocks located around this outflow pipe. This investigation, incorporated the results conducted on the other three underwater outflow pipes(i.e., Chishui creek outflow pipe, Chinese Petroleum Corporation underwater petroleum pipe off Kaohsiung Harbor and Liuchiuyu water transport pipe), concluded that as far as the buried underwater pipes that are thicker than 1m in diameter are concerned, the integrated system of side scan sonar and sub-bottom profiler provides an useful and trustful tool to get the locations and the buried depth of outflow pipes, as well as the distribution of the protective concrete blocks around these pipes. As to the pipes that are less than 20cm in diameter, the pipes can¡¦t be detected by this equipment. For the pipes that are between 20cm and 1m in diameter, due to limited information collected up to this moment, extensive investigation need to be conducted until a clear understanding can be deduced.
15

Stoffaustrag und Bodenbearbeitung

Machulla, Galina, Nitzsche, Olaf, Schmidt, Walter-Alexander 29 November 2010 (has links) (PDF)
Der vorliegende Bericht stellt Ergebnisse des zweijährigen Projektes "Veränderte Pflanzenschutzmittel- und Nährstoffausträge bei bodenschonender Bewirtschaftung - Risikoanalyse und -vorsorge" vor. Auf landwirtschaftlichen Flächen in der Lommatzscher Pflege wurden mit einer Beregnungsanlage Starkniederschläge (worst-case-Szenario) simuliert. Die Untersuchungen zu Wasser- und Agrochemikalientransport fanden auf Flächen statt, die konventionell mit Pflug, konservierend flach bearbeitet bzw. in Direktsaat bestellt wurden. Die Auswirkungen auf vertikale und horizontale Stofftransporte, insbesondere von Nitrat-Stickstoff und dem Totalherbizid Durano mit dem Wirkstoff Glyphosat wurden untersucht.
16

Numerical Vlasov–Maxwell Modelling of Space Plasma

Eliasson, Bengt January 2002 (has links)
The Vlasov equation describes the evolution of the distribution function of particles in phase space (x,v), where the particles interact with long-range forces, but where shortrange "collisional" forces are neglected. A space plasma consists of low-mass electrically charged particles, and therefore the most important long-range forces acting in the plasma are the Lorentz forces created by electromagnetic fields. What makes the numerical solution of the Vlasov equation a challenging task is that the fully three-dimensional problem leads to a partial differential equation in the six-dimensional phase space, plus time, making it hard even to store a discretised solution in a computer’s memory. Solutions to the Vlasov equation have also a tendency of becoming oscillatory in velocity space, due to free streaming terms (ballistic particles), in which steep gradients are created and problems of calculating the v (velocity) derivative of the function accurately increase with time. In the present thesis, the numerical treatment is limited to one- and two-dimensional systems, leading to solutions in two- and four-dimensional phase space, respectively, plus time. The numerical method developed is based on the technique of Fourier transforming the Vlasov equation in velocity space and then solving the resulting equation, in which the small-scale information in velocity space is removed through outgoing wave boundary conditions in the Fourier transformed velocity space. The Maxwell equations are rewritten in a form which conserves the divergences of the electric and magnetic fields, by means of the Lorentz potentials. The resulting equations are solved numerically by high order methods, reducing the need for numerical over-sampling of the problem. The algorithm has been implemented in Fortran 90, and the code for solving the one-dimensional Vlasov equation has been parallelised by the method of domain decomposition, and has been implemented using the Message Passing Interface (MPI) method. The code has been used to investigate linear and non-linear interaction between electromagnetic fields, plasma waves, and particles.
17

The Relation of Left Ventricular Geometry to Left Ventricular Outflow Tract Shape and Stroke Volume Index Calculations

Lavine, Steven J., Obeng, George B. 01 May 2019 (has links)
Background: Stroke volume (SV) and aortic valve area calculations require the left ventricular (LV) outflow tract (LVOT) or aortic annular area calculations that involve squaring the respective diameters. Area calculation errors became evident with transcatheter aortic valve replacement where areas were underestimated due to an elliptical annulus. We hypothesized that LVOT and annular shape are more elliptical in patients with greater relative LV wall thickness (RWT) leading to underestimation of SV index using 2D Doppler echocardiography. Methods: We studied 203 consecutive patients referred to an outpatient noninvasive laboratory for Doppler echocardiograms which included acceptable 3-dimensional images. 3-dimensional assessment of the LVOT at 3–5 mm from the valve insertion, at the site of valve insertion, and at the sinus of Valsalva (SOV) was performed with assessment of the minor axis (MN), major axis (MJ), and areas at mid-systole. SV index was calculated from LVOT and annular diameters obtained from 2-dimensional echo and from 3-dimensional LVOT areas. Results: An inverse relation of RWT with MN/MJ at mid-systole for the LVOT (r = 0.5812, P < 0.0001) and annulus (r = 0.6865, P < 0.0001) was noted. LVOT and annulus areas were similar among groups at mid-systole. SV index calculated from 2D LVOT dimensions was significantly smaller than using 3D LVOT areas (35.6 ± 8.9 vs 53.6 ± 16.1 mL, P < 0.0001). Conclusion: There is an inverse relation between MN/MJ and RWT at the LVOT and aortic annulus despite the LVOT and annular areas being similar across most geometries resulting in SV index underestimation calculated using LVOT diameters vs 3D LVOT areas.
18

A Multi-Year Analysis of Irrigation Practices Affecting Salt Outflow: A Case Study in Uintah Basin

Cannon, Joel R. 01 May 1977 (has links)
The Colorado River is subject to a salinity problem which affects the downstream user. It has been suggested that approximately 40% of the salinity in the Colorado River results from irrigation return flow. The evapotranspiration process extracts nearly pure water for plant use leaving behind soluable salts which may become part of the return flow. These salts adversely affect the orop yield for the downstream user. Farmers' contributions to the irrigation return flow have been criticized. With the criticisms have been many suggestions on salinity control, including restriction of salt outflow at the farm level through either voluntary or mandatory means. An important element in the policy making procedure is a good information base showing the economic effect of salinity control on the individual farm to which the control affects. To date such a base has not been available. Such an Information base is necessary to establish policies and implement programs to solve the salinity problem in the Colorado River.
19

On the Distances and Energetics of AGN Outflows

Edmonds, Bartlett D. 10 September 2013 (has links)
Active galactic nuclei (AGN) ubiquitously show outflows. It is now widely recognized that these outflows are key components in the evolution of super-massive black holes and their host galaxies. As important as these outflows are, we still lack sufficient understanding of their structure and energetics. The majority of the work presented in this thesis involved photoionization modeling of AGN outflows along with analysis of density diagnostics in order to determine the distances and energetics of observed outflows. The main findings of these analyses are that 1) outflows are often at distances of hundreds to thousands of parsecs from the central supermassive black hole and 2) quasars outflows can be sufficiently powerful to provide feedback in galactic evolution scenarios. We also find in some cases that the recombination timescales of metal ions are long compared with the flux variability timescales. The large distances we find provide a challenge to current outflow models. For example, these outflows cannot be connected with an accretion disk surrounding the supermassive black hole as assumed in some models. Furthermore, the outflows may be out of equilibrium as we find in Mrk 509. In this case, a thorough understanding of time-dependent photoionization effects is necessary. In this thesis, I include early steps toward understanding time-dependent photoionization as well as ionization studies of accretion disk winds. The main results of these theoretical studies is that 1) the appearance of multiple ionization components in an outflow can be an artifact of the incorrect assumption that the outflow is in ionization equilibrium and 2) the shielding gas required in accretion-disk-wind models should have a clear signature in UV spectra, but none has been observed to date. / Ph. D.
20

Study of Interstellar Medium in Star-Forming Galaxies at the Violent Epoch of Galaxy Evolution / 銀河進化の激動期における星形成銀河の星間物質の研究

Seko, Akifumi 23 March 2017 (has links)
京都大学 / 0048 / 新制・課程博士 / 博士(理学) / 甲第20180号 / 理博第4265号 / 新制||理||1613(附属図書館) / 京都大学大学院理学研究科物理学・宇宙物理学専攻 / (主査)教授 太田 耕司, 准教授 栗田 光樹夫, 教授 長田 哲也 / 学位規則第4条第1項該当 / Doctor of Science / Kyoto University / DFAM

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