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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.
121

Mechanical and histological disturbances in advanced heart failure and cardiac transplantation

Cameli, Matteo January 2016 (has links)
The general purpose of this thesis is to establish capability and accuracy of speckle tracking echocardiography (STE) in assessing left atrial (LA), left ventricular (LV) and right ventricular (RV) function and their correlation with myocardial fibrosis, filling pressure and clinical outcomes in advanced heart failure (HF) patients before and after heart transplantation (HT). I demonstrated that HT recipients had impaired LV twist dynamics in the form of reduced rotation twist angle and untwist rate but time to peak twist was not different from the age matched controls and other cardiac surgical patients. With a longitudinal study conducted on patients with refractory HF, the best prognostic power has been shown by RV strain analysis. Among the indexes of LV function, the LV ejection fraction (LVEF) demonstrated the lowest diagnostic accuracy; instead LV global circumferential strain (GCS) showed a better sensitivity and specificity than LV global longitudinal strain (GLS). When analyzing the relationship between different severity of myocardial fibrosis and LV cavity function, the strongest function parameter that correlated with severity of myocardial fibrosis was GLS. In contrast, none of diastolic LV function or even measures of exercise capacity correlated with myocardial fibrosis. In patients with end-stage HF, global peak atrial longitudinal strain (PALS), an index of atrial reservoir function was dependent by pulmonary capillary wedge pressure (PCWP) and LV fibrosis, but not influenced by LV systolic function. Results from this study confirm previous evidence of correlation between impaired global PALS and increased PCWP.
122

Magnetresonanztomographische Detektion von Fibrose im linken Vorhof bei Patienten nach Schlaganfall / Detection of left atrial fibrosis in patients after ischemic stroke using cardiovascular magnetic resonance imaging

Wandelt, Laura Kristin 11 July 2019 (has links)
No description available.
123

Assessment of Left Ventricular Function and Hemodynamics Using Three-dimensional Echocardiography

Shahgaldi, Kambiz January 2010 (has links)
Left ventricular (LV) volumes and ejection fraction (EF) are important predictors of cardiac morbidity and mortality. LV volumes provide valuable prognostic information which isparticularly useful in the selection of therapy or determination of the optimal time for surgery. Two-dimensional (2D) echocardiography is the most widely used non-invasive method forassessment of cardiac function, 2D echocardiography has however several limitations inmeasuring LV volumes and EF since the formulas for quantifications are based on geometricalassumptions. Three-dimensional (3D) echocardiography has been available for almost twodecades, although the use of this modality has not gained wide spread acceptance. 3D echocardiography can overcome the above mentioned limitation in LV volume and EF evaluation since it is not based on geometrical assumption. 3D echocardiography has been shownin several studies to be more accurate and reproducible with low inter- and intraobservervariability in comparison to 2D echocardiography regarding the measurements of LV volumesand EF. The overall aim of the thesis was to evaluate the feasibility and accuracy of 3D echocardiography based-methods in the clinical context. In Study I the feasibility of 3D echocardiography was investigated for determination of LV volumes and EF using parasternal, apical and subcostal approaches. The study demonstrated that the apical 3D echocardiography view offers superior visualization. Study II tested the possibility of creating flow-volume loops to differentiate patients with valvular abnormalities from normal subjects. There were significant differences in the pattern from flow-volume loops clearly separating the groups. In Study III the visual estimation, “eyeballing” of EF was evaluated with two- and tri-plane echocardiography in comparison to quantitative 3D echocardiography. The study confirmed that an experienced echocardiographer can, with a high level of agreement estimate EF both with two- and tri-plane echocardiography. Study IV exposed the high accuracy of stroke volume and cardiac output determination using a3D biplane technique by planimetrically tracing the left ventricular outflow tract and indicating that an assumption of circular left ventricular outflow tract is not reliable. In Study V, two 3D echocardiography modalities, single-beat and four-beat ECG-gated 3D echocardiography were evaluated in patients having sinus rhythm and atrial fibrillation. Thesingle-beat technique showed significantly lower inter-and intraobserver variability in LV volumes and EF measurements in patients having atrial fibrillation in comparison to four-beat ECG-gated acquisition due to absence of stitching artifact. All studies demonstrated good results suggesting 3D echocardiography to be a feasible andaccurate method in daily clinical settings. / degree of Medical DoctorQC 20100629
124

Stará a nová levice na politické scéně České republiky / Old and new left in Czech Republic

Blažeková, Radka January 2017 (has links)
The topic of the diploma thesis is a comparison of the old and new left in the Czech Republic. The diploma thesis focuses on a comparison of the selected relevant left-wing political groups operating in the Czech Republic. The thesis examines differences and similarities between the KSČM, the socialist wing of ČSSD on one side and the Green Party and the left-liberal tendencies and offshoots of the ČSSD (such Idealists) on the other hand. The work is divided into three main parts. The first part of the thesis is theoretical. The theoretical part defines main terms such as a political party, political movement, left-right axis of the political spectrum, the old left, the new left etc. The explanation of the terms is very important for understanding the thesis. In the second part of this thesis, I analyze single significant and relevant political parties. I focus on the origin and development of political parties and their electoral program, their attitude to selected issues, electorate, potential cooperation between themselves and so on. The third part is comparative. The goal of this thesis is to find out whether the analyzed political parties fulfill leftist characteristic. Next goal of this thesis is to find out whether the classification on left-right axis of the political spectrum is still...
125

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.
126

Renin-angiotensin-aldosterone system genes and the complex hypertrophic phenotype of hypertrophic cardiomyopathy

Carstens, Nadia 12 1900 (has links)
Thesis (PhD)--Stellenbosch University, 2012. / ENGLISH ABSTRACT: Left ventricular hypertrophy (LVH) is a strong independent predictor of cardiovascular morbidity and mortality, while its regression is associated with an improved clinical prognosis. It is, therefore, vital to elucidate and fully comprehend the mechanisms that contribute to LVH development and to identify markers that indicate a strong predisposition to the development of severe cardiac hypertrophy, before its occurrence. Hypertrophic cardiomyopathy (HCM) serves as a model to investigate LVH development. This primary cardiac disease is characterised by LVH in the absence of increased external loading conditions and is caused by defective sarcomeric proteins, as a result of mutations within the genes encoding these proteins. However, the hypertrophic phenotype of HCM is largely complex, as we see strong variability in the extent and distribution of LVH in HCM, even in individuals with the same disease-causing mutation from the same family; this points toward the involvement of additional genetic and environmental modifiers. Components of the renin-angiotensin-aldosterone system (RAAS) influence LVH indirectly, through their key role in blood pressure regulation, but also directly, due to the direct cellular hypertrophic effects of some RAAS components. Previous genetic association studies aimed at investigating the contribution of RAAS variants to LVH were largely centred on a subset of polymorphisms within the genes encoding the angiotensin converting enzyme (ACE) and angiotensin II type 1 receptor genes, while the renin section and RAAS components downstream from ACE remained largely neglected. In addition, most previous studies have reported relatively small individual effects for a small subset of RAAS variants on LVH. In the present study we, therefore, employ a family-based genetic association analysis approach to investigate the contribution of the entire RAAS to this complex hypertrophic phenotype by exploring both the individual as well as the compound effects of 84 variants within 22 RAAS genes, in a cohort of 388 individuals from 27 HCM families, in which either of three HCM-founder mutations segregate. During the course of this explorative study, we identified a number of RAAS variants that had significant effects on hypertrophy in HCM, whether alone or within the context of a multi-variant haplotype. Through single variant association analyses, we identified variants within the genes encoding angiotensinogen, renin-binding protein, the mannose-6-phosphate receptor, ACE, ACE2, angiotensin receptors 1 and 2, the mineralocorticoid receptor, as well as the epithelial sodium channel and the Na+/K+-ATPase β-subunits, that contribute to hypertrophy in HCM. Using haplotype-based association analyses, we were able to identify haplotypes within the genes encoding for renin, the mannose-6-phosphate receptor, angiotensin receptor 1, the mineralocorticoid receptor, epithelial sodium channel and Na+/K+-ATPase α- and β subunits, as well as the CYP11B1/B2 locus, that contribute significantly to LVH. In addition, we found that some RAAS variants and haplotypes had statistically significantly different effects in the three HCM founder mutation groups. Finally, we used stepwise selection to identify a set of nine risk-alleles that together predicted a 127.80 g increase in left ventricular mass, as well as a 13.97 mm increase in maximum interventricular septal thickness and a 14.67 mm increase in maximum left ventricular wall thickness in the present cohort. In contrast, we show that a set of previously identified “pro-LVH” polymorphisms rather poorly predicted LVH in the present South African cohort. This is the first RAAS investigation, to our knowledge, to provide clear quantitative effects for a subset of RAAS variants indicative of a risk for LVH development that are representative of the entire pathway. Our findings suggest that the eventual hypertrophic phenotype of HCM is modulated by the compound effect of a number of RAAS modifier loci, where each polymorphism makes a modest contribution towards the eventual phenotype. Research such as that presented here provides a basis on which future studies can build improved risk profiles for LVH development within the context of HCM, and ultimately in all patients with a risk of cardiac hypertrophy. / AFRIKAANSE OPSOMMING: Linker ventrikulêre hipertrofie (LVH) is 'n sterk onafhanklike voorspeller van kardiovaskulêre morbiditeit en mortaliteit, terwyl LVH regressie verband hou met ‘n verbeterde kliniese voorspelling. Dit is dus noodsaaklik om die meganismes wat bydra to LVH ontwikkeling ten volle te verstaan en merkers wat 'n sterk geneigdheid tot die ontwikkeling van ernstige kardiale hipertrofie te identifiseer, voordat dit voorkom. Hipertrofiese kardiomiopatie (HKM) dien as 'n model om LVH ontwikkeling te ondersoek. Hierdie primêre hartsiekte word gekenmerk deur LVH en word meestal veroorsaak deur foutiewe sarkomeer proteïene as gevolg van mutasies binne die gene wat kodeer vir hierdie proteïene. Die hipertrofiese fenotipe van HKM is egter grootliks kompleks; ons sien, by voorbeeld, sterk veranderlikheid in die omvang en die verspreiding van LVH in HKM, selfs in individue met dieselfde siekte-veroorsakende mutasie binne dieselfde gesin, wat dui op die betrokkenheid van addisionele genetiese en omgewing modifiseerders. Komponente van die renien-angiotensien-aldosteroon sisteem (RAAS) beïnvloed LVH indirek, deur middel van hul belangrike rol in bloeddruk regulasie, maar ook direk, as gevolg van die direkte sellulêre hipertrofiese gevolge van sommige RAAS komponente. Vorige genetiese assosiasie studies wat daarop gemik was om die bydrae van RAAS variante LVH te ondersoek, was hoofsaaklik gesentreer op 'n groepie polimorfismes binne die gene wat kodeer vir die “angiotensin converting enzyme” (ACE) en angiotensien II tipe 1-reseptor gene, terwyl die renien gedeelte en RAAS komponente stroomaf van ACE meestal nie ondersoek was nie. Daarbenewens het die meeste vorige studies relatief klein individuele gevolge gerapporteer vir 'n klein groepie RAAS variante op LVH. In die huidige studie het ons dus 'n familie-gebaseerde genetiese assosiasie-analise benadering gebruik om die bydrae van die hele RAAS tot hierdie komplekse hipertrofiese fenotipe te ondersoek deur 'n studie van die individuele-, sowel as die saamgestelde effekte van 84 variante binne 22 RAAS gene, in 'n groep van 388 individue vanaf 27 HKM families, waarin een van drie HCM-stigter mutasies seggregeer. Gedurende die loop van hierdie studie het ons 'n aantal RAAS variante wat ‘n beduidende uitwerking op HKM hipertrofie geïdentifiseer, hetsy alleen of binne die konteks van' n multi-variant haplotipe. Deur middel van enkele variant assosiasie toetsing het ons variante geïdentifiseer binne die gene wat kodeer vir angiotensinogen, renien-bindende proteïen, die mannose-6-fosfaat reseptor, ACE, ACE2, angiotensien reseptore 1 en 2, die mineralokortikoïd reseptor, sowel as die epiteel natrium kanaal en Na+/ K+-ATPase β-subeenhede, wat bydra tot HKM hipertrofie. Deur die gebruik van haplotipe-gebaseerde assosiasie ontleding was ons in staat om haplotipes te identifiseer binne die gene wat kodeer vir renien, die mannose-6-fosfaat reseptor angiotensien reseptor 1, die mineralokortikoïd reseptor, epiteel natrium kanaal en die Na+/ K+-ATPase α-en β subeenhede, sowel as die CYP11B1/B2 lokus, wat aansienlik bydra tot LVH. Verder het ons bevind dat sommige RAAS variante en haplotipes statisties beduidende verskillende effekte gehad het in die drie HKM stigter mutasie groepe. Laastens, het ons stapsgewyse seleksie gebruik om 'n stel van nege risiko-allele wat saam' n toename van 127.80 g in linker ventrikulêre massa, sowel as 'n 13.97 mm toename in maksimum ventrikulêre septale dikte, en' n 14.67 mm verhoging in maksimum linker ventrikulêre wanddikte voorspel, te identifiseer in die huidige kohort. In teenstelling hiermee wys ons dat 'n stel van voorheen geïdentifiseerde "pro-LVH" polimorfismes swakker gevaar het as LVH-voorspellers in die huidige Suid-Afrikaanse kohort. Hierdie is die eerste RAAS ondersoek, tot ons kennis, wat ‘n duidelike kwantitatiewe gevolge vir 'n stel RAAS variante wat ‘n verhoogde risiko tot LVH ontwikkeling aandui, wat verteenwoordigend is van die hele RAAS. Ons bevindinge dui daarop dat die uiteindelike hipertrofiese fenotipe van HKM gemoduleer word deur die saamgestelde effek van 'n aantal RAAS wysiger loki, waar elke polimorfisme ' n beskeie bydrae maak tot die uiteindelike fenotipe. Navorsing soos dié wat hier aangebied word dien as 'n basis waarop toekomstige studies kan bou vir ‘n verbeterde risiko-profiel vir LVH ontwikkeling binne die konteks van die HKM, en uiteindelik in alle pasiënte met' n verhoogde risiko vir kardiale hipertrofie.
127

Saturation flows of protected dual left turn lanes

Cone, Fred, 1933- January 1989 (has links)
The objective of this study was to provide an estimate of the protected dual left turn saturation flow rates in the Tucson area. The data were collected from dual left turn lanes at six intersections. The headway times were measured in order to calculate the saturation flow rates at each of the study sites. Observations were made at four intersections with left turn protected and at two intersections with permitted plus protected left turns. Saturation flow was measured from the third to the last vehicle in the queue. Observations were made during the time of expected peak traffic flow. A stop watch was used to measure the time intervals to the nearest tenth of a second. The saturation flow rates were then calculated and varied from 1621 to 2017 Vehicles Per Hour of Green Per Lane (VPHGL) for the inside lane to 1737 to 1802 VPHGL in the outside lane.
128

Improving the Left Degree Distribution of Fountain Codes in the Finite-Length Regime

Hayajneh, Khaled 22 August 2013 (has links)
Fountain codes were introduced to provide higher reliability, lower complexities, and more scalability for networks such as the Internet. In this thesis, we study Luby- Transform (LT) codes which are the realization of Fountain codes. In the LT codes, a sparse random factor graph is dynamically generated on both the encoder and decoder sides of the communications channel. The graph is generated from an ensemble degree distribution. The LT codes are also known as rateless codes, in the sense that they can generate potentially limitless codeword symbols from original data and self-adjust to channels with different erasure probabilities. LT Codes also have a very low encoding and decoding complexities when comparing with some traditional block codes, e.g., Reed Solomon (RS) codes and Low-Density-Parity-Check (LDPC) codes. Therefore, LT Codes are suitable for many different kinds of applications such as broadcast transmission. LT codes achieve the capacity of the Binary Erasure Channel (BEC) asymptotically and universally. For finite lengths, the search is continued to nd codes closer to the capacity limits at even lower encoding and decoding complexities. Most previous work on single-layer Fountain coding targets the design via the right degree distribution. The left degree distribution of an LT code is left as Poisson to protect the universality. For finite lengths, this is no longer an issue; thus, we focus on the design of better codes for the BEC and noisy channels as well at practical lengths. We propose two encoding schemes for BEC and noisy channels by shaping the left degree distribution. Our left degree shaping provides codes outperforming regular LT code and all other competing schemes in the literature. For instance, at a bit error rate of 10_{-7} and k = 256, our scheme provides a realized rate of 0.6 which is 23.5% higher than Sorensen et al.'s scheme over BEC. In addition, over noisy channels our proposed scheme achieves an improvement of 14% in the released rates at k = 100 and 30 Belief Propagation (BP) iterations. / Thesis (Master, Electrical & Computer Engineering) -- Queen's University, 2013-08-22 19:40:59.885
129

Left-libertarian theory of rights

Millett Fisher, Arabella Marie Amy January 2012 (has links)
The human rights that are defended in libertarian literature tend to be limited in scope, which entails that the duties that people can be compelled to fulfil are similarly minimal. For this reason a commitment to libertarianism tends to be seen as incompatible with support for subsistence rights, enforceable positive duties, and redistributive taxation, since each one of these issues may require the infringement of libertarian property rights. In this thesis I aim to challenge these assumptions about libertarianism and to show that if a more plausible reading of libertarianism is adopted – what has come to be known as left-libertarianism – then this will generate a more substantial range of rights and correlative duties which are not only compatible with redistributive taxation, but in fact entail it. I show that libertarianism, despite its contention that human rights are exclusively negative, does not rule out subsistence rights provided that these are understood as negative rights, for example: a right not to be deprived of the means of subsistence, or deprived of a clean living environment. Negative rights can be violated not only by individuals or by institutions, but also by individuals supporting institutions. In order to respect the negative rights of others it is necessary to refrain from supporting or contributing to institutions that violate these rights. Moreover, failure to respect these rights brings about a positive duty of rectification, demonstrating the potential for positive libertarian duties even in the absence of positive rights. Since the manner in which rights can be violated is extensive, so is the scope of those individuals that owe rectification. The fundamental libertarian rights of self-ownership, which I characterise as three property rights – over the body, over the faculties (including talents, abilities and labour) and over what one can produce through exercising those faculties in conjunction with the body – demonstrate how we can come to have property rights over external objects, but self-ownership does not confer permanent private property rights over unlimited external worldly resources. In fact, a robust right of self-ownership is incompatible with the radically inegalitarian appropriation with which libertarianism is ordinarily associated. Given the equal rights of selfownership of every individual, it is far more plausible to conceive of the world as held in some egalitarian manner, rather than as unowned and available for appropriation in such a way that would disadvantage latecomers. I propose an egalitarian understanding of world ownership which comprises common ownership of land, and joint ownership of other external worldly resources such as oil and minerals. Taking the injustice of radically inegalitarian appropriation in conjunction with a duty to rectify past injustices, there follows a libertarian argument for redistribution, but crucially this redistributive taxation is collected not on income but on natural resource use. On a left-libertarian theory of rights, then, there is no right to appropriate unlimited resources, but there is a right to redistribution in the event of past injustices, including the misappropriation of worldly resources.
130

Writing Chinese Characters: Right or Left? : The Chinese Discriminatory Policy of Left-Handedness Correction in Terms of Handwriting

Xie, Jiawei January 2016 (has links)
Chinese left-handed are found to be very few, especially in terms of handwriting. The Chinese educational policy that fully entitles teachers in primary school to change the left-handed students to write with their right-hand, by nudging and even force, is found to be mainly blamed as the main cause. The thesis is to raise the ethical discussion and define this policy as being discriminatory against the left-handed by checking the features, definition and identification of discrimination, and reasons forming and supporting such a discriminatory policy will be taken into the major consideration as the source of discrimination. Therefore, the thesis is to propose solutions to help with the abolishment of the policy and the elimination of the prejudicial attitudes toward the left-handed, especially in terms of writing. The thesis itself, due to the limit of previous research and scientific support, has its own blindness or disadvantage, however, such a work could be helpful with the later discussion.

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