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The impact of a termination on subsequent pregnancy outcomes has been widely studied. It has been suggested that women who terminate a pregnancy are more likely to have an adverse outcome of a subsequent pregnancy, either miscarriage, or a preterm or low birthweight baby. However, the evidence to date is inconclusive and in some cases contradictory. Hypothesis: It is hypothesised that those who had terminated their first pregnancy are more likely to have an adverse outcome of a subsequent pregnancy, (either miscarriage, preterm delivery (<37 weeks), or low birthweight ((<2500g) as a proxy for gestation). They are also more likely to have shorter gestation at miscarriage, and the gestation at miscarriage is associated with method of termination. Also, women are more likely to show a dose-response in three-pregnancy series, with increasing numbers of consecutive terminations associated with increasingly poorer outcomes. Data and Methodology: Setting and Sample: Aberdeen maternity hospital (AMH) is the level III consultant-led maternity unit for NHS North of Scotland Region. It provides care for pregnant women both with and without complications and for sick neonates. The data were extracted from the Aberdeen Maternity and Neonatal Databank (AMND), with the sample restricted to Aberdeen city women in 1970-1999, and only singleton pregnancy events were included. Outcomes The study group was Termination-Birth (TB) and this group was compared to three comparison pregnancy history groups, Miscarriage-Birth (MB), Birth-Birth (BB) and Birth (B). The outcomes are preterm and low birthweight deliveries and the sub-categories of preterm and low birthweight. In addition, miscarriage on the index event is also considered as an outcome. Methods: The distributions of gestation and birthweight were examined between and within study groups for outcomes of preterm and low birthweight deliveries, and logistic and multinomial regression was used to assess the impact of selected potentially confounding socio-demographic and pregnancy related characteristics on the odds of delivering at different levels of preterm and low birthweight by pregnancy history. The gestation at miscarriage of the index subsequent event is also examined between study groups, as is the method of termination for women whose first pregnancy was terminated. In addition, two and three pregnancy sequences are examined to determine if there was a ‘dose-response’ effect of termination of pregnancy. Results: For women from group TB, the overall difference in average adjusted gestation at delivery is approximately 1 day less for women from group TB compared to women from group MB, and only 2 days from women with only a history of births, these results could be considered clinically insignificant. This thesis has shown that compared with women with a previous birth, and after adjusting for possible confounding factors, births after a previous termination were consistently more likely to result in a preterm delivery. Women who terminated a first pregnancy have an increased likelihood of preterm delivery from a public health perspective, with an overall 40% increase in risk for preterm birth for women from group TB when compared to women from group B (OR 1.35 95%CI 1.15, 1.58). These increased odds of preterm delivery for group TB are very similar to those for women from group MB (OR 1.45, 95%CI 1.18, 1.79). Similarly, after adjustment for potential confounding factors, women from group TB were consistently more likely to deliver a low birthweight baby, when compared to women with from group B, (OR 1.18 95%CI 1.00, 1.38). Women from group MB were also significantly more likely to deliver a low birthweight baby after adjustment for possible confounding factors (OR 1.42 95%CI 1.16, 1.72). Few if any of the explanatory variables are directly modifiable, and the PAF associated with women from group TB is relatively small, when compared to other significant potential risk factors. Women who terminated a first pregnancy were significantly more likely, after adjustment for socio-demographic characteristics to miscarry late (OR 1.74, 95%CI 1.07, 2.84), but there was no difference between medical and surgical terminations. Finally, there was no evidence of a dose response of termination for either preterm or low birthweight deliveries, although there was marked evidence of a dose response of miscarriage. Conclusions The results from a clinical and public health point of view may appear to be contradictory, in that there is an approximate 40% increase in relative risk for preterm delivery, but only an adjusted absolute difference of two days lower gestation at birth for women from group TB. PAF findings indicate only a small overall reduction in the number of preterm deliveries if the exposure to the risk factor of a previous termination was eliminated. Women who undergo a termination should therefore receive full information on factors which might have an influence on the outcome of a subsequent pregnancy, and in addition medical information given to the women should cover details about the termination process, including methods of termination, possible complications, post termination follow up and future contraception.

The wide application of fluid injection has caused a concern of the potential critical risk associated with induced seismicity. To help clarify the concern, this dissertation proposes a statistical approach for assessing seismic transitions associated with fluid injections by scientifically analyzing instrumental measures of seismic events. The assessment problem is challenging due to the uncertain effects of wastewater injections on regional seismicity, along with the limited availability of seismic and injection data. To overcome the challenge, three statistical methods are developed, with each being focused on a different aspect of the problem. Specifically, a statistical method is developed for early detection of induced seismicity, with the potential of allowing for site managers and regulators to act promptly and preparing communities for the increased seismic risk; the second method aims for addressing the further need of quantitatively assessing the transition of induced seismicity, which can reveal the underlying process of induced seismicity and provide data to support probabilistic seismic hazard analysis; and finally, the third method steps further to characterize the process of spatial distribution of induced seismicity, which accounts for spatial evolution of induced seismicity. All the proposed methods are built on the principles of Bayesian technique, which provides a flexible inference framework to incorporate domain expertise and data uncertainty. The effectiveness of the proposed methods is demonstrated using the earthquake dataset for the state of Oklahoma, which shows a promising result: the detection method is able to issue warning of induced seismicity well before the occurrence of severe consequences; the transition model provides a significantly better fit to the dataset than the classical model and sheds light on the underlying transition of induced seismicity in Oklahoma; and the spatio-temporal model provides a most comprehensive characterization of the dataset in terms of its spatial and temporal properties and is shown to have a much better short-term forecasting performance than the “naïve methods”. The proposed methods can be used in combination as a decision-making support tool to identify areas with increasing levels of seismic risk in a quantitative manner, supporting a comprehensive assessment to decide which risk-mitigation strategy should be recommended.

La dégradation induite par éclairement (Light Induced Degradation : LID), s'exprimant par la perte de qualités électriques, est devenu un problème récurrent dans les modules photovoltaïques de silicium de qualité métallurgique (compensé en dopants). Compte tenu des nombreuses impuretés présentes dans ce matériau, la compréhension des mécanismes mis en jeu est très complexe et reste incomplète. Pour cette raison, les seuls mécanismes identifiés à ce jour sont liées à l'action de complexes BO2i. Les travaux réalisés durant cette thèse sur différentes qualités de plaquettes de silicium de type p, ont mis en évidence la participation d'une autre réaction, activée thermiquement à 0.68 eV. D'après nos résultats cette réaction, associée aux complexes CiOi, n'est pas systématique. Elle semble agir si les échantillons ont une concentration en carbone substitutionnel supérieure ou égale à celle du dopage net et s'ils sont soumis à des températures T ≥ 50°C. Cette réaction, intervenant dans la LID, est donc indépendante du degré de compensation du matériau. Nous avons également mis en évidence un phénomène de dégradation à l'obscurité (DID : Degradation In Dark), conduisant à des pertes électriques analogues à celles obtenues par la LID. Cette DID, apparaissant uniquement par chauffe, semble faire intervenir des réactions similaires à celles de la LID. Son étude permet de supposer que des impuretés primaires (lacunes, auto-interstitiel) participent également à ces phénomènes. / Light induced degradation (LID), leading to a deterioration of electrical properties, has become a recurring problem in photovoltaic modules based on metallurgical grade silicon. Due to the many impurities present in the material (compensated by dopants), the mechanisms involved in this phenomenon are very complex and not very well understood. For this reason, the only reactions identified are related to the action of BO2i complexes.Works carried out during this thesis on different grades of p-type silicon wafers have highlighted the involvement of another thermally activated reaction at 0.68 eV. According to our results, this reaction, associated with CiOi complexes, is not systematic. It seems to act if the samples have a substitutional carbon concentration greater than or equal to the net doping and if they are subjected to temperatures T ≥ 50° C. We also highlighted the emergence of a phenomenon of degradation in the dark (DID), leading to similar electrical losses to those obtained by LID. This DID, appearing only by heating, seems to involve similar reactions to LID. Its study allows us to assume that the primary impurities (vacancies, self-interstitials) are also involved in these phenomena.