• Refine Query
  • Source
  • Publication year
  • to
  • Language
  • 38
  • 21
  • 13
  • 8
  • 5
  • 3
  • 3
  • 2
  • 2
  • 2
  • 1
  • 1
  • 1
  • 1
  • Tagged with
  • 115
  • 22
  • 14
  • 13
  • 11
  • 10
  • 9
  • 9
  • 9
  • 8
  • 8
  • 8
  • 8
  • 7
  • 7
  • 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

Pbx4 is Required to Restrict Second Heart Field and Ventricular Outflow Tract Size

Linstrum, Kelsey January 2015 (has links)
No description available.
52

Development, Characterization, And Implementation Of An In Vitro Model Of Cerebrospinal Fluid Outflow Across The Arachnoid Granulations

Holman, David W. 11 September 2008 (has links)
No description available.
53

Prediction of trabecular meshwork-targeted micro-invasive glaucoma surgery outcomes using anterior segment OCT angiography / 前眼部OCTアンギオグラフィーを用いた線維柱帯切開術効果予測

Okamoto, Yoko 23 March 2022 (has links)
京都大学 / 新制・課程博士 / 博士(医学) / 甲第23793号 / 医博第4839号 / 新制||医||1057(附属図書館) / 京都大学大学院医学研究科医学専攻 / (主査)教授 大森 孝一, 教授 花川 隆, 教授 渡邊 直樹 / 学位規則第4条第1項該当 / Doctor of Medical Science / Kyoto University / DFAM
54

Topology optimization for the duct flow problems in laminar and turbulent flow regimes / 層流および乱流の内部流れを対象としたトポロジー最適化

Kubo, Seiji 25 March 2019 (has links)
京都大学 / 0048 / 新制・課程博士 / 博士(工学) / 甲第21753号 / 工博第4570号 / 新制||工||1712(附属図書館) / 京都大学大学院工学研究科機械理工学専攻 / (主査)教授 西脇 眞二, 教授 松原 厚, 教授 黒瀬 良一 / 学位規則第4条第1項該当 / Doctor of Philosophy (Engineering) / Kyoto University / DFAM
55

Subsidiary Innovation and Diffusion: An Integrated Approach on Learning of Subsidiaries from Diverse Local Environments

Mu, Shaohua Carolyn 01 September 2003 (has links)
This dissertation investigates the factors that influence the learning of subsidiaries from their local environment and the sequential knowledge outflow from the subsidiaries. Scholars have recognized the ability to learn from diverse local environments as a critical source of competitive advantage for multinational corporations (MNCs). However, the factors influencing the extent to which MNCs learn from local environments in order to develop innovative capabilities have not been well understood. Considering the complexity of institutional environments faced by subsidiaries, this dissertation explores cross-level factors that influence subsidiary learning from diverse local environments. At interface levels, a subsidiary's local embeddedness and its learning strategy influence the awareness of local strategic knowledge by the subsidiary. At context levels, local market competition and corporate entrepreneurial culture affect the motivation of a subsidiary to learn from diverse local environments. Finally at subsidiary level, top management team heterogeneity impacts the capability of a subsidiary to learn. This dissertation applies both qualitative and quantitative research methods. Multiple-case studies provide rich details, while survey research tests the generalizability of the proposed conceptual model. Overall, the empirical evidence supports the impact of local embeddedness, learning strategy and corporate entrepreneurial culture on subsidiary learning, and in turn, on knowledge outflow. The impact of top management team heterogeneity turns insignificant upon the simultaneous inclusion of all other factors. The influence of local competition is absent. The control variables include size, technology resources, and internationalization. This dissertation contributes to both MNC and organizational learning literature. The major contribution to MNC literature is the advancement of the understanding of knowledge acquisition and creation of MNCs by learning from the local environment. The cross-level approach with subsidiary as the unit of analysis provides a unique perspective. The major contribution of this dissertation to organizational learning literature lies in the development of a learning framework, and its application to MNC context with empirical tests. This dissertation presents potentials to advance the local responsiveness-global integration framework with a knowledge-based view. / Ph. D.
56

How Do Quasars Impact Their Host Galaxies? From the Studies of Quasar Outflows in Absorption and Emission

Xu, Xinfeng 27 May 2020 (has links)
"Quasar-mode feedback" occurs when momentum and energy from the environment of accreting supermassive black hole couple to the host galaxy. One mechanism for such a coupling is by high-velocity (up to ~0.2c) quasar-driven ionized outflows, appearing as blue-shifted absorption and emission lines in quasar spectra. Given enough energy and momentum, these outflows are capable of affecting the evolution of their host galaxies. This dissertation presents the studies of emission and absorption quasar outflows from different perspectives. (1). By conducting large broad absorption line (BAL) quasar surveys in both Sloan Digital Sky Survey and Very Large Telescopes (VLT), we determined various physics properties of quasar absorption outflows, e.g., the electron number density ((n<sub>e</sub>), the distance of outflows to the central quasar (𝑅), and the kinetic energy carried by the outflow (𝐸̇<sub>k</sub>). We demonstrated that half of the typical BAL outflows are situated at 𝑅 > 100 pc, i.e., having the potential to affect the host galaxies. (2). Our group carried out a Hubble Space Telescope program (PI: Arav) for studying the outflows in the Extreme-UV, collaborating with Dr. Gerard Kriss from Space Telescope Science Institute (STScI). We developed a novel method to fit the multitude of quasar absorption troughs efficiently and accurately. We have identified the most energetic quasar-driven outflows on record and discovered the largest acceleration and velocity-shift for a quasar absorption outflow. (3). By using the VLT data, Xu led the project to study the relationships between BAL outflows and emission line outflows. We found possible connections between these two types of quasar outflows, e.g., the luminosity of the [𝑂<sub>III</sub> λ5007 emission profile decreases with increasing n<sub>e</sub> derived from the BAL outflow in the same quasar. These findings are consistent with BAL and emission outflows being different manifestations of the same wind, and the observed relationships are likely a reflection of the outflow density distribution. / Doctor of Philosophy / Super massive black holes (SMBHs) are believed to exist in the center of almost all massive galaxies, where the brightest accreting ones are named "quasars". "Quasar-mode feedback" occurs when momentum and energy from the environment of accreting SMBHs couple to the host galaxy. One mechanism for such a coupling is by high-velocity (up to ~0.2c) quasar-driven ionized outflows, appearing as blue-shifted absorption and emission lines in quasar spectra. Given enough energy and momentum, these outflows are capable of affecting the evolution of their host galaxies. Such quasar outflows are invoked to explain a variety of observations, e.g., the chemical enrichment of the intergalactic medium (IGM), the shape of the observed quasar luminosity function, and the self-regulation of the growth of the SMBHs. In this dissertation, I focus on studying the emission and absorption outflows observed in quasars spectra, collected with the largest telescopes and most powerful instruments in the world. (1). By conducting large broad absorption line (BAL) quasar surveys in both Sloan Digital Sky Survey and Very Large Telescopes (VLT), we determined various physics properties of quasar absorption outflows, e.g., the electron number density (n<sub>e</sub>), the distance of outflows to the central quasar (𝑅), and the kinetic energy carried by the outflow (𝐸̇<sub>k</sub>). We demonstrated that half of the typical BAL outflows are situated at 𝑅 > 100 pc, i.e., having the potential to affect the host galaxies. (2). Our group carried out a Hubble Space Telescope program (PI: Arav) for studying the outflows in the Extreme-UV, collaborating with Dr. Gerard Kriss from Space Telescope Science Institute (STScI). We developed a novel method to fit the multitude of quasar absorption troughs efficiently and accurately. We have identified the most energetic quasar-driven outflows on record and discovered the largest acceleration and velocity-shift for a quasar absorption outflow. (3). By using the VLT data, Xu led the project to study the relationships between BAL outflows and emission line outflows. We found possible connections between these two types of quasar outflows, e.g., the luminosity of the [𝑂<sub>III</sub>] λ5007 emission profile decreases with increasing n<sub>e</sub> derived from the BAL outflow in the same quasar. These findings are consistent with BAL and emission outflows being different manifestations of the same wind, and the observed relationships are likely a reflection of the outflow density distribution.
57

Stanovení kapacity rozstřikovacího uzávěru v podmínkách omezeného výtoku / Hollow cone valve capacity in the restricted outflow conditions

Nehudek, Adam January 2015 (has links)
The thesis aims to determine the influence partial or complete submerge of hollow cone valve by outflow on its capacity without space restrictions, by outflow into discharge chamber and by outflow into water tunnel of circular cross section. The valve capacity is for mutual comparability purposes usually characterized by discharge coefficient. Research works have been performed on a spatial hydraulic model of the valve with inlet diameter D = 67 mm and an apex angle of a cone 90°. Values of the discharge coefficient obtained from measurements were statistically analyzed. The dependence of discharge coefficient, expressed by energy head, on submerged level was approximated by an exponential function. Exponent value of this function express the dependance rate of valve capacity on downstream water level. This procedure didn’t demonstrate signifiant dependance downstream water level on hollow cone valve capacity, only on tests at outflow to water tunel showed a low increase in the discharge coefficient partly due to the influence of kinetic energy of the stream flowing out of the tunnel on the energy head and also due to underpressure. Independence of discharge coefficient value on valve head has been prooved for head greather than 232 mm. Also was defined 3 stages of interaction outflow jet from valve and downstream water, some of them may cause on real waterworks structures unfavorable situations (may affect excessive load on valve by pressure pulsations). The presented results allow better evaluation of bottom outlets capacity at higher water levels, when the valves are flooded. Significant effect of sufficient aeration (especially in long water tunnels) on valve capacity was also confirmed. Taking into account on the specifics of hollow jet valves and cone valves, it is possible to generalize some of this resultos on them as well.
58

Design, analysis, testing, and evaluation of a prosthetic venous valve

Tanner, Daniel Edward 09 April 2013 (has links)
Chronic Venous Insufficiency (CVI) is characterized by chronic venous hypertension from blood pooling in the lower limbs. The resulting symptoms include leg pain, varicose veins, fatigue, venous edema, skin pigmentation, inflammation, induration, and ulceration. Reflux from incompetent venous valves is a factor in up to 94% of individuals with CVI. Current treatments of CVI include compression stockings, drug therapy, vein disabling, venous stenting, and surgical correction with varying rates of success. However, a minimally invasive correction of deep venous reflux does not currently exist. A transcatheter prosthetic venous valve has the potential to be an effective, minimally invasive treatment for deep venous reflux which could treat up to 1.4 million individuals in the United States suffering from venous ulceration and make more than 1.7 billion dollars each year. Previously developed prosthetic venous valves have had problems with competency, patency, thrombogenicity, biocompatibility, and incorrect sizing. To meet the clinical need a prosthetic valve needs to be developed which succeeds where previous valves have failed. This thesis describes the design, analysis, pre-clinical testing, and evaluation of a novel prosthetic venous valve. Design specifications for an effective prosthetic venous valve were created. Verification tests were developed and performed which demonstrated that the valve met every design specification. Finite element and computational fluid dynamics simulations were performed to analyze the valve and calculated a maximum shear rate of 2300 s-1 in the valve during the high forward flow after a Valsalva maneuver. The valve is made of a biocompatible material that has low thrombogenicity, Poly(vinyl-alcohol) cryogel. On the average, the valve allows less than 0.5 mL/min of reflux at low and high retrograde pressures even after 500,000 cycles, indicating that it will reduce the reflux of individuals with venous reflux by more than 99.4%. The valve closes in less than 0.07 seconds and allows the distal pressure to rise to an average of 7% of the equilibrium pressure 30 seconds after a simulated ankle flexion. The valve increases the outflow resistance an average of 2.3 mmHg*min/L which is much less than obstruction levels,≥ 5 mmHg*min/L. The valve can fit in a 16 French catheter and is capable of percutaneous delivery. The base of the valve is 1.5 times the diameter of the vein in which it is to be implanted to help correct orientation upon deployment. Fluid behind the valve’s leaflets is ejected with a forward flow rate of 400 mL/min, suggesting that thrombus formation will not occur at this location. A stented valve remained patent in a porcine blood flow loop for 3 hours. The valve remains competent without buckling in a constricted vein at rest. The valve can expand to fit a vein with a maximum diameter 1.4 times the valve's initial diameter with low risk of tearing or leaflet prolapse. An IACUC protocol for a 12 week study to test the valve in sheep was prepared and approved. A study to evaluate the valve in humans is proposed with endpoints that can be tested for statistical significance and compared with other treatments for CVI. A set of valves which will correct reflux in the majority of common femoral, femoral, and popliteal deep veins is proposed and a sizing guide for surgeons is provided. The minimum distance between prosthetic valves placed in the same vein segment is 13 cm. A comparison of this valve with previously developed prosthetic venous valves and recommendations for work to be performed in the future are given. The valve proposed in this work is the only valve to meet all design specification for an effective prosthetic venous valve, and therefore shows great potential to be a minimally invasive treatment for deep venous reflux.
59

Analýza vlivu potenciálně vybudovaného vodního díla na odtok vody z vybraného povodí pomocí hydrologického modelování

REZEK, Alfred January 2019 (has links)
The object of this dissertation is to describe the influence of water works on the outflow from a watershed through the Hydrologic Modelling System Hec HMS. It is a direct application to the particular watershed of the Bílský Stream. In the theoretical part about relevant literature, solutions to the topics related to this issue are found. It focuses especially on the water balance in the watershed; the outflow from the watershed and other factors by which the watershed is influenced; extreme flows and flood activity with appropriate security steps such as water basins. At the end of the part on the literature, there are five different systems for creating hydrologic models with the specialisation on the Hec HMS model. The practical part is about preparing input data for the hydrologic model and its subsequent creation. Particular runoff from different N-year precipitation (N = 2, 10, 50 and 100) are compared. Two hydrologic models have been created for comparison, one with the watershed without a reservoir and the second one with a reservoir included. The resultant part is about watching flows, volumes of runoffs and the tranformation of the flood wave in a reservoir between N-year precipitation and two different models of watershed.
60

Variabilidade oceânica associada à variabilidade climática da vazão na bacia do rio São Francisco / Oceanic variability related to river outflow at São Francisco Hydrographic basin

Costa, Karine Mirieli dos Santos 06 February 2012 (has links)
Esta pesquisa tem como objetivo avaliar a relação existente entre o comportamento anual dos oceanos e o da vazão na Bacia do Rio São Francisco, Brasil, para o período de 1968 a 2004. Foram construídos modelos de regressão linear múltipla para simular o valor da vazão anual em Ponte da Taquara, Alto São Francisco, com base em índices climáticos e no valor médio da Temperatura da Superfície do Mar (TSM) em áreas específicas dos oceanos Pacífico e Atlântico. Os índices climáticos considerados foram a Oscilação Decadal do Pacífico (ODP), Indice de Oscilação Sul (IOS) e anomalias de TSM nas regiões de Niño. Os padrões oceânicos de correlação linear entre a TSM do Pacífico e a vazão dos postos do Alto São Francisco e o Médio São Francisco, indicam valores positivos em toda a costa oeste da América do Norte e do Sul e região equatorial e fortes sinais negativos na costa leste da Ásia e Austrália. Este padrão é bastante semelhante ao padrão espacial do primeiro modo obtido pela aplicação de análise multivariada à TSM no Oceano Pacífico, que é associado à Oscilação Multidecadal do Pacífico. A consideração de defasagem mensal no cálculo do coeficiente de correlação linear entre os valores de vazão e TSM indicam que a TSM dos meses mais próximos ao da vazão têm maior potencial para serem considerados como seus preditores. Observa-se a diminuição da correlação linear entre TSM do Pacífico e a vazão dos postos do Médio e Baixo São Francisco em relação aos postos do Alto São Francisco. O que sugere que o Oceano Pacífico apresenta maior influência na variabilidade da vazão nos postos localizados mais ao sul da Bacia do São Francisco. Por outro lado, observa-se o aumento dos valores do coeficiente de correlação linear no Atlântico Sul principalmente para a vazão dos postos do Médio e Sub-Médio, indicando possivelmente a maior influência do Oceano Atlântico na vazão de postos localizados mais a nordeste da bacia hidrográfica considerada. O padrão oceânico indicado pelos valores de correlação linear entre a TSM e os postos do Sub- Médio São Francisco indica a presença de um dipolo meridional, com anomalias negativas e positivas na bacia do Atlântico Sul tropical e subtropical. O IOS e ODP apresentam maior valor de correlação para a vazão observada no Alto e Médio São Francisco. As regiões selecionadas nos oceanos Pacífico, Atlântico e Índico e os índices Niño1+2, Niño 3 e Niño 4 para a construção do modelo linear para a simulação da vazão anual suavizada explicam 96% da variância total da vazão. No caso da vazão sem suavização as variáveis selecionadas pelo modelo elaborado explicam 52% da variância total. O padrão atmosférico anômalo associado aos dois primeiros subperíodos da vazão em Ponte da Taquara, de 1968 a 1978 e de 1979 a 1988, caracterizados em média por anomalias negativas e positivas, respectivamente, apresenta condições atmosféricas específicas às anomalias observadas da vazão. Em geral, anomalias negativas (positivas) de vazão em Ponte da Taquara são acompanhadas por ODP negativa, com anomalias negativas (positivas) de TSM no Pacífico Equatorial. / This research concerned to propose a valuation about the relationship between annual oceanic behavior and river outflow at São Francisco Hydrographic Basin, in Brazil, for the period from 1968 to 2004. Linear model based on multiple regression were built for annual river outflow at Ponte da Taquara, located at High São Francisco sub-basin. Climatic indexes and Sea Surface Temperature (SST) averages for selected areas over Pacific and Atlantic oceans were taken as independent variables in the modeling. Pacific Decadal Oscillation (PDO), Southern Oscillation Index (SOI) and SST anomalies at the Niño regions were also considered as independent variables in the modeling. The specific oceanic areas were selected through linear correlation calculation between river outflow at High São Francisco and SST. Oceanic patter represented by linear correlation between Pacific SST and river outflow at High São Francisco and Medium São Francisco shows positive values throughout the west coast of North and South America and the equatorial areas and, high negative values at oceanic areas to the east of Asia and Australia. This patter is quite similar to that obtained as the first mode of multivariate analysis applied over Pacific basin, and is related to the PDO. The consideration of temporal lag between SST river outflow monthly values showed that the smaller interval provide the best linear correlation. Linear correlation patter over Pacific is more significant for river outflow observed at the southern area of São Francisco Basin in relation to those located at northern areas. This aspect suggests that Pacific Ocean plays a more significant role to determination of river outflow observed at the south of the hydrographic basin. On the other hand, linear correlation values are greater at South Atlantic when river outflow for Sub-Medium São Francisco is considered. This result suggests that South Atlantic Ocean can play a greater role for the determination for climatic variability for river outflow observed at northern areas of São Francisco Basin. The oceanic correlation pattern for South Atlantic Ocean also shows a dipole mode, between tropical and subtropical latitudes, for fluvial stations located at the northern areas of the hydrographic basin. SOI and PDO present greater correlation values for river outflow observed at High and Medium São Francisco Basin. Ocean Pacific, Atlantic and Indian and the indexes Niño1+2, Niño 3 e Niño 4 variables, selected for the linear model elaboration to river outflow simulation, explain 96% of the total variance. In the case of not smoothed data, the variance explained by the linear model is equal to 52%. The atmospheric averaged patterns for the considered two first subperiods, from 1968 to 1978 and from 1979 to 1988, that are characterized by negative and positive river outflow anomalies at High São Francisco, present atmospheric conditions closely related to the observed river outflow anomalies. In general, river outflow negative (positive) anomalies at High São Francisco are related to negative PDO and SST negative anomalies (positive) at equatorial Pacific.

Page generated in 0.0396 seconds