Tricuspid regurgitation (TR), back flow of blood from the right ventricle to the right atrium, has been reported in approximately 85% of the population, with 16% having mild or severe TR. Patients with untreated moderate to severe TR are likely to experience decreased exercise capacity and have increased morbidity and mortality, thus affecting the patient's quality of life. Current methods of repair offer limited rates of success, and many patients require further operations to correct returning levels of TR. Incomplete repair may be due to incomplete understanding of the functional anatomy and mechanics of the TV and the underlying causes of TR. It was hypothesized that alterations in the geometry of tricuspid valve annular and subvalvular apparatus induced by ventricular dilatation determine the severity of TR. In vivo measurements of papillary muscle (PM) position in patients with single or biventricular dilatation revealed PM displacement away from the center of the annulus as compared to control patients. Additionally, pulmonary arterial pressure, annulus area, ventricular size and apical displacement of the anterior PM were highly correlated with the severity of TR. An in vitro right-heart simulator was developed to investigate isolated mechanics of TR. Through these in vitro studies it was demonstrated that the tricuspid valve begins to leak at only 40% dilation, much lower than the mitral valve. Additionally, it was shown that isolated PM displacement resulted in significant TR. The highest levels of TR were achieved with a combination of annular dilatation and PM displacement. Alterations in leaflet coaptation, as quantified by measuring the amount of leaflet available for coaptation and leaflet mobility were observed with annular dilatation and PM displacement, both isolated and combined. The changes in leaflet coaptation resulted in redistribution of the forces on the chords originating from the anterior PM and inserting into the anterior and posterior leaflets. The findings herein provide the clinical and scientific community with a mechanistic understanding of the tricuspid valve to further improve intervention and repair of TV disease.

Ce travail se place dans le cadre de la recherche de céramiques susceptibles de fonctionner à plus hautes température que la zircone yttriée, le système le plus employé actuellement pour constituer la couche isolante des barrières thermiques de turbines, aéronautiques ou terrestres. Une analyse des critères auxquels doit répondre une telle céramique a conduit à choisir la famille des perovskites, et, en conclusion de calculs de conductivité thermique par dynamique moléculaire, à sélectionner BaMg1/3Ta2/3O3 (BMT), un composé dont le point de fusion est supérieur à 2900°C. Un mode d'élaboration par voie solide a été développé pour obtenir cet oxyde sous forme dense. En guise de référence, des matériaux denses de zircones yttriées complètement stabilisées ont également été élaborés. Ces deux oxydes ont ensuite été caractérisées expérimentalement : structure par diffraction de rayons X, conductivité thermique jusqu'à 1200°C à partir de la mesure de la diffusivité thermiques par méthode flash laser, coefficient de dilatation entre 200 et 1200°C. Une étu de du gravage thermique de joints de grains, avec suivi par microscopie à force atomique du profil de joints après traitements entre 1100°C et 1400°C, a permis dans certains cas de déterminer le coefficient de diffusion en surface. Il ressort de cette étude que, si la perovskite BMT possède un ensemble de propriétés intéressantes pour constituer une barrière thermique : stabilité structurale, conductivité thermique à 1200°C du même ordre que celle de la zircone yttriée (autour de 2 W.m-1.K-1), coefficient de dilatation élevé (11.10-5 /K entre 200 et 1200°C), des phénomènes de sublima tion sont susceptibles de perturber la stabilité de couches à très hautes températures.

In this study, it was aimed to develop conservation methodologies for the historic sandstones using the case of Nemrut Mount Monument to help their survival in open air conditions. The main conservation approach of this study was holistic as well as aiming at minimum intervention targeted to the problem areas. The most important weathering forms of Nemrut Sandstones were material loss due to loss of scales and granular disintegration as well as detachments by scales, back weathering due to loss of scales, cracking, granular disintegration, rounding/notching and discoloration/biological deposition. Deterioration mechanisms of sandstones were studied on deteriorated and relatively sound sandstones by nondestructive methods of UPV and QIRT, and by microstructural analyses using thin section, XRD and SEM-EDX analyses. In addition, the changes in physical and physcomechanical properties such as, color, bulk density, effective porosity, hydric, hygric and thermal dilatation and CEC of clays were determined. Sandstone deterioration was caused by swelling of clay minerals distributed in their matrix and clay accumulations between the detaching scales. Considerable thermal dilatation characteristics was also an important decay factor. Iron oxides caused discoloration at the surfaces, their phase changes was thought to be important in decay. The use of surfactant DAA, to control clay swelling was found to decrease the hydric dilatation by 40%. The consolidation treatments with nanosilica and silicate dispersions namely Funcosil KSE500STE, SytonX3, KSE300 and KSE100 have improved physicomechanical properties as followed by UPV measurements and decreased hydric dilatation. Their long term behaviour needed to be further investigated.

published_or_final_version / Pharmacology and Pharmacy / Doctoral / Doctor of Philosophy

Diss. (sammanfattning) Stockholm : Karol. inst., 2003. / Härtill 4 uppsatser.

Diss. (sammanfattning) Göteborg : Göteborgs universitet, 2007. / Härtill 4 uppsatser.

Thesis (Ph.D.)--Indiana University, Dept. of Political Science, 2006. / Title from PDF t.p. (viewed Nov. 17, 2008). Source: Dissertation Abstracts International, Volume: 67-12, Section: A, page: 4681. Adviser: Edward G. Carmines.

Made available in DSpace on 2014-06-11T19:26:56Z (GMT). No. of bitstreams: 0 Previous issue date: 2008-10-23Bitstream added on 2014-06-13T20:47:37Z : No. of bitstreams: 1 benzatti_lfl_me_sjrp.pdf: 732390 bytes, checksum: 881740f368084e6df5cf0fa8794b0073 (MD5) / Neste trabalho estudamos transformações quaseconformes no contexto dos octônios, que são hipercomplexos de oito dimensões. Por não preservar a magnitude dos ângulos, mapeamentos quaseconformes causam uma dilatação linear. A partir da definição métrica de quaseconformidade, utilizamos a forma binomial para mostrar que a distância jf(y) ¡ f(x)j pode ser escrita como um polinômio em r. Com isso, pudemos desenvolver não são um conjunto de fórmulas como também um método computacional simplificado para o cálculo analítico da dilatação. Posteriormente, utilizamos ferramentas gráficas para vizualizar as consequências da dilatação. / In this work we study quasiconformal mappings related to octonionic algebra. Since quasicon- formal mappings do not preserve the magnitude of the angles they cause a linear dilatation. We show that it also happens to 8-dimensional hipercomplex. Based on the metric de¯nition of quasiconformal mapping we show that the distance jf(y)¡f(x)j is a polynomial of variable r. Then it¶s possible to make not only a set of formulas but also a computacional method to calculate the dilatation. We also use some graphical tools to visualize the consequences of dilatation.

Introduction: It had been suggested by a number of recent studies that ultrasonography could become an alternative to digital vaginal examination (VE) for assessing the progress of pregnant women in labour. However, no systematic review and meta-analysis on the effectiveness of ultrasonography was available. Systematic Review: A systematic review and meta-analysis was conducted to investigate the success rate of ultrasonography in comparison with digital VE and the level of agreement between the two methods, in terms of estimating fetal head position, head station and cervical dilatation. Systematic Review Findings: This review found that ultrasonography has a higher success rate than digital VE in estimating fetal head position. Ultrasonography was also in high agreement with digital VE in estimating cervical dilatation, with insignificant difference in the success rate of the two methods in terms of detecting cervical dilatation. There was also a significant correlation between the two methods in estimating head station. However, it was also found by the review that, existing primary studies were mainly conducted in tertiary settings of developed countries. Further research was therefore needed from the perspective of non-tertiary settings and also from developing country settings. In addition, further research was also needed to assess the diagnostic performance of ultrasound in detecting active labour, since it is associated with cervical dilatation. The diagnostic performance of ultrasound in detecting engaged fetal head had also not been investigated, which is necessary because it is associated with head station. Primary Research Aim: As a consequence of these systematic review findings, a primary study was conducted in another clinical setting in a developing country. The aim was to investigate the reproducibility, practicality and acceptability of using ultrasonography to monitor the progress of pregnant women in labour. Research Methods: A cross-sectional study was conducted in a teaching hospital in Ghana. The agreement between ultrasound and digital VE was statistically analysed for the estimation of fetal head position, head station and cervical dilatation. Further statistical analysis was conducted on the diagnostic performance of ultrasound in detecting engaged fetal head, and the diagnostic performance of ultrasound in detecting active labour. A quantitative survey of mothers’ acceptance of intrapartum ultrasound was also conducted. Lastly, caregivers’ views on the practicality of using ultrasound in this developing country setting was also investigated in a qualitative survey. Results of Primary Research: The results regarding reproducibility were as follows: (i) a high between-method agreement was found in the estimation of cervical dilatation, with high ultrasound sensitivity and specificity in detecting active labour; (ii) a statistically significant between-method agreement was found in the estimation of head station, with high ultrasound sensitivity and specificity in detecting engaged fetal head; (iii) a weak between-method agreement was found in the estimation of fetal head position, with ultrasound having a higher success rate than digital VE. The results regarding acceptability showed that most mothers accepted the use of intrapartum ultrasound, and were willing to have the procedure for their future care during labour and childbirth. They also preferred ultrasound to digital VE. With regards to practicality, the responses of caregivers indicate that the introduction of intrapartum ultrasound in this setting could serve as a good complement to digital VE in a number of ways. However, putting it into practice would require wider availability of physical and technical resources. Conclusion: The findings of the reproducibility study were consistent with existing studies in other clinical settings which were investigated in the systematic review. This suggests that ultrasound is a reliable method for assessing the progress of pregnant women in labour. In addition, the unique contribution to existing knowledge obtained from this study was a high ultrasound sensitivity and specificity in detecting active labour and engaged fetal head which were reported for the first time. The findings on mothers’ acceptability were also consistent with existing studies in other settings, which is an indication that there is high acceptance of intrapartum ultrasound by mothers from different settings and cultures. Lastly, caregivers’ views on the practicality of the use of ultrasound during labour indicate that the regular use of intrapartum ultrasound for assessing the progress of labour in pregnant women may require additional resources to make it practicable in this and other similar settings.

Ischaemia reperfusion injury (IR-injury) occurs when blood supply to a certain area of the body is blocked, and is subsequently followed by reperfusion. During the period of ischaemia, tissue is damaged as a result of lack of oxygen. Rapid reperfusion is mandatory, but unfortunately causes damage in addition to the damage induced by ischaemia alone. While a prolonged period of ischaemia is harmful to the bodily tissue, short periods of ischaemia interspersed with short bouts of reperfusion have protective effects. This mechanism is called ischaemic preconditioning (IPC). In this thesis, the impact of co-morbidity and age on IR-injury and IPC are explored. Moreover, the possible role of IPC to enhance exercise performance is investigated. Finally an attempt is made to understand the interchangeable effects of IPC and exercise performance in the prevention of IR-injury. Using the brachial artery endothelial function as a surrogate marker, first the consequences of IR-injury in both young and older individuals on endothelial function were studied. It was also assessed whether IPC could prevent endothelial IR-injury. It was found that endothelial function in both groups declined, when IR-injury was not preceded with IPC. However, when IPC was applied prior to IR-injury, a protective effect was detected in young subjects, but not in older participants. In chapter 5, this study was repeated in patients with heart failure, as they are at an increased risk for IR-injury. While in both groups a significant decline in endothelial function was observed, a much larger decline was established in the heart failure group. Moreover, IPC failed to protect against endothelial dysfunction in heart failure patients after IR-injury. The third study presented in this thesis, focused on the question whether exercise performance enhancement during a 5-km time trial was comparable when IPC on the upper legs was applied immediately before the time trial versus 24 hours (24-IPC) prior to exercise. Interestingly, a significant and strong correlation was found in finish time between acute IPC and 24-IPC, suggesting comparable effects of IPC and 24-IPC on exercise performance. In a follow-up study, it was determined whether local IPC applied on the upper arm, or remote IPC applied on the legs, would lead to an improved maximum incremental arm crank exercise test in individuals with a complete spinal cord lesion. The main finding was that upper arm IPC led to an increased performance enhancement, whilst remote IPC (stimulus below the lesion) did not lead to any significant differences. These studies help to inform the best or most practical application of IPC in daily life situations. Some previous work has suggested that exercise may resemble some of the effects of IPC. More specifically, acute exercise might possess the same protective effects against ischaemia-reperfusion injury as IPC. Therefore, in young healthy individuals it was studied, whether an acute bout of endurance or interval exercise is able to protect against brachial endothelial IR-injury. It was established that interval exercise prevented endothelial dysfunction after an IR stimulus, while no protective effect of endurance exercise was found. It was concluded that interval exercise, but not endurance exercise, prevented endothelial dysfunction after an ischaemic period. In conclusion, this thesis provides further evidence for the protective effects of (remote) IPC, both on the prevention of endothelial IR-injury as well as improvement in exercise performance. However, effects may depend on the protocol and population studied.