Statistical modelling of repeated and multivariate survival data

The emphasis of this thesis lies on complex survival data and on the modelling of this kind of data. Statistical models are developed or adapted and applied to five different real data sets, which all contain repeated censored measurements. To take into account the correlation between these repeated data, a frailty is considered in all statistical analysis used. Extensions of and alternatives for frailty models are considered. The centre-effect on survival after bone marrow transplantation is studied in chapter 2. Models that are able to take into account a time-dependent frailty are proposed and compared. In chapter 3 survival analysis approaches are used for modelling an ecological capture-recapture data set. In chapter 4, the emphasis lies on the frailty model used in a genetic context. Our model is applied on age at onset of Huntington disease. Chapter 5 concerns the estimation of the correlation between processes with frailties. The approach is applied on the Dutch part of the data set from the Caprie trial, involving cardiac, cerebral and peripheral atherosclerosis. In chapter 6, the point of interest is the marginal survivor curve in different simulated balanced and unbalanced longitudinal situations. Finally, in chapter 7 a general summary can be found.UBL - phd migration 201

Contained/Contenu

An exhibition of ceramic and glass works by 7 international artists, in the ceramic museum Musée Ariana in Geneva, curated by Ana Quintero Perez, of the museum, and Monique Deul independent curator and founder of Taste Contemporary in Geneva. Alison Britton contributed 5 ceramic works to the exhibition

Nitrogen-rich indium nitride

Elastic recoil detection analysis, using an incident beam of 200 MeV Au ions, has been used to measureindium nitride films grown by radio-frequency sputtering. It is shown that the films have nitrogen-rich stoichiometry. Nitrogen vacancies are therefore unlikely to be responsible for the commonly observed high background carrier concentration. Ultraviolet Raman and secondary ion mass spectroscopymeasurements are used to probe the state of the excess nitrogen. The nitrogen on indium anti-site defect is implicated, though other possibilities for the site of the excess nitrogen, such as molecular nitrogen, or di-nitrogen interstitials cannot be excluded. It is further shown that a shift in the (0002) x-ray diffraction peak correlates with the excess nitrogen, but not with the oxygen observed in some samples.K.S.A.B. would like to acknowledge the support of an Australian Research Council Fellowship. We would also like to acknowledge the support of the Australian Research Council through a Large grant and a Discovery grant; the support of a Macquarie University Research Development Grant, and the Australian Institute of Nuclear Science and Engineering for SIMS access

Selection of reference genes for gene expression studies in ultraviolet B-irradiated human skin fibroblasts using quantitative real-time PCR

<p>Abstract</p> <p>Background</p> <p>Reference genes are frequently used to normalise mRNA levels between different samples. The expression level of these genes, however, may vary between tissues or cells and may change under certain circumstances. Cytoskeleton genes have served as multifunctional tools for experimental studies as reference genes. Our previous studies have demonstrated that the expression of vimentin, one cytoskeletal protein, was increased in ultraviolet B (UVB)-irradiated fibroblasts. Thus, we examined the expression of other cytoskeleton protein genes, <it>ACTB </it>(<it>actin, beta</it>), <it>TUBA1A </it>(<it>tubulin, alpha 1a</it>), and <it>TUBB1 </it>(<it>tubulin, beta 1</it>), in human dermal fibroblasts irradiated by UVB to determine which of these candidates were the most appropriate reference genes.</p> <p>Results</p> <p>Quantitative real-time PCR followed by analysis with the NormFinder and geNorm software programmes was performed. The initial screening of the expression patterns demonstrated that the expression of <it>VIM </it>was suppressed after UVB irradiation at doses ≥25 mJ/cm²and that the expression of <it>TUBA1A </it>was significantly reduced by UVB doses ≥75 mJ/cm²in cultured human dermal fibroblasts. The analysis of the experimental data revealed <it>ACTB </it>to be the most stably expressed gene, followed by <it>GAPDH </it>(<it>aglyceraldehyde-3-phosphate dehydrogenase</it>), under these experimental conditions. By contrast, <it>VIM </it>was found to be the least stable gene. The combination of <it>ACTB </it>and <it>TUBB1 </it>was revealed to be the gene pair that introduced the least systematic error into the data normalisation.</p> <p>Conclusion</p> <p>The data herein provide evidence that <it>ACTB </it>and <it>TUBB1 </it>are suitable reference genes in human skin fibroblasts irradiated by UVB, whereas <it>VIM </it>and <it>TUBA1A </it>are not and should therefore be excluded as reference genes in any gene expression studies involving UVB-irradiated human skin fibroblasts.</p