Ce mémoire illustre la difficile déclinaison du paradigme de l'optimalité lors de sa confrontation aux principes de réalité de systèmes toujours plus complexes. Après avoir récapitulé l'expérience de recherche acquise à travers des contributions variées, qui nous emmènent de problèmes de contrôle en dimension infinie à des applications dans les domaines du spatial, de l'énergie et de l'automobile, les développements spécifiques en matière de prospective long terme seront l'objet d'une attention particulière. Ainsi, le credo que l'optimalité est un canevas nécessaire pour envisager les enjeux d'une modélisation du long terme sera défendu, soutenant l'idée que cette approche devra rester centrale dans nos perspectives de recherche. Mais dans la tradition d'une formation "à la française", cette réflexion ne saura être menée sans revenir au préalable sur les grands principes sous jacents à l'optimalité et leur liaison naturelle avec l'étude des systèmes dynamiques.

This thesis presents data on two separate areas relevant to the prevention of HIV and sexually transmitted infection (STI) transmission in homosexual men. These data arise from the community-based Health in Men (HIM) cohort of HIV-negative homosexual men in Sydney. First, the association of circumcision status with HIV and STIs was examined. Older age, ethnicity and country of birth were demographic factors independently associated with circumcision status. Self-report was a valid measure of circumcision status in this population. Overall, being circumcised was associated with a non-significant reduced risk of HIV seroconversion in the HIM cohort (HR 0.76, 95% CI 0.41-1.41, p=0.381). Among the one-third of participants predominantly practising the insertive role in anal intercourse (AI), being circumcised was associated with a significantly reduced risk of HIV infection (HR 0.15, 95% CI 0.03-0.80, p=0.026). Circumcised HIM participants also had a lower risk of incident syphilis (HR 0.35, 95% CI 0.15-0.84, p=0.019), however circumcision status had no significant effect on the remainder of prevalent and incident STIs examined. Second, risk factors for pharyngeal gonorrhoea and chlamydia were investigated. The BD ProbeTec nucleic acid amplification test (NAAT) had a positive predictive value (PPV) for pharyngeal gonorrhoea diagnosis of only 30.4% (95% CI 25.2-36.1%) when compared to a previously validated NAAT targeting the gonococcal porA pseudogene. Pharyngeal gonorrhoea was common in HIM, mostly occurred without concurrent anogenital infection and may frequently spontaneously resolve. Infection was independently associated with younger age (p-trend=0.001), higher number of male partners (p-trend=0.002), contact with gonorrhoea (p<0.001) and insertive oro-anal sex with casual partners (p-trend=0.044). Pharyngeal chlamydia was less common but a high prevalence/incidence ratio suggested that infection may persist in the pharynx for long periods. Pharyngeal chlamydia was independently associated with receptive penile-oral sex with casual partners (p-trend=0.009). In conclusion, circumcision may have a role as an HIV prevention intervention among the subgroup of homosexual men who predominantly practise insertive rather than receptive AI. Regular screening of the pharynx including a validated supplemental NAAT for gonorrhoea diagnosis may prevent much transmission to anogenital sites, whereas chlamydia occurs too infrequently in the pharynx to recommend routine screening in homosexual men.

Venous thromboembolism (VTE), comprising deep venous thrombosis (DVT) and pulmonary embolism (PE), is a common and preventable cause of morbidity among individuals and hospital in-patient mortality. Further, it imposes a substantial burden upon the community and its health care system and economy. Studies performed in Western societies suggest that the annual incidence of DVT is about 0.8 to 1.2 per 1,000, PE about 0.3 to 0.6 per 1,000, and VTE about 1.0 to 1.8 per 1,000. However, it is not known if these estimates can be generalised to the Australian population because of differences in ethnic composition and other risk factors for VTE among the different populations. In this thesis, I undertook a prospective, community-based cohort study over a 13-month period in 2003 – 2004 to determine the incidence and crude event rate of symptomatic, objectively verified VTE in north-east metropolitan Perth. The study population was broadly representative of the national Australian population in terms of age, sex and ethnic distribution. Cases were identified through multiple overlapping sources. The incidence of DVT, PE and VTE in the community were 0.52 (95% confidence interval, CI: 0.41 – 0.63), 0.31 (95% CI: 0.22 – 0.40) and 0.83 (95% CI: 0.69 – 0.97) per 1000 per year, respectively. The annual incidence of DVT, adjusted to the World Standard population, was 0.35 (95% CI: 0.26 – 0.44) per 1000, PE 0.21 (95% CI: 0.14 – 0.28) per 1000 and VTE 0.57 (95% CI: 0.47 – 0.67) per 1000. The crude event rate for VTE was 0.85 (95% CI: 0.71 – 0.99) per 1000 per year. These findings suggest that the incidence of DVT, PE and VTE are lower than in other Western societies studied. Possible reasons include a lower prevalence of exposure to causal risk factors (genetic and environmental) and incomplete case ascertainment. Knowledge of the local incidence and event rate allows health planners to allocate appropriate resources and evaluate cost-effective preventive measures.

Thesis (Ph.D.)--York University, 2006. Graduate Programme in Psychology. / Typescript. Includes bibliographical references (leaves 122-152). Also available on the Internet. MODE OF ACCESS via web browser by entering the following URL: http://gateway.proquest.com/openurl?url_ver=Z39.88-2004&res_dat=xri:pqdiss&rft_val_fmt=info:ofi/fmt:kev:mtx:dissertation&rft_dat=xri:pqdiss:NR29500

Diss. (sammanfattning) Umeå : Umeå universitet, 2006. / Härtill 4 uppsatser.

Texte remanié de: Thèse--Sc. écon.--Paris I, 1973. / Bibliogr. p. 201-205.

Thesis--University of Oklahoma. / Bibliography: leaf 87.

Thesis--University of Oklahoma. / Bibliography: leaves 83-88.

The purpose of this study was to examine the development of the ability to multitask in children along with other executive control processes that likely underlie goal-directed behavior in novel situations. 35 children, ages 7-11, completed an experimental multitasking paradigm, the Children’s Multiple Activities Game (CMAG), and an existing measure, the Six Parts Test (SPT) as well as two working memory and inhibition tasks and a prospective memory task. Results indicated that multitasking ability improves across this age range and is related to a number of executive abilities. Performance on the CMAG was related to a number of executive abilities, while the SPT was unrelated to these measures. To our knowledge, this is the first study to investigate the development of this ability in children. Findings will be discussed in terms of how this ability develops in relation to cognitive processes that are crucial and account for its variation.

Après la Seconde Guerre mondiale, surtout à partir du début des années 1960, et jusqu’à la fin des années 1980, plusieurs projets de recherche sur le futur ont été menés par des équipes internationales avec pour objectif la promotion d’une « conscience globale », soit un sentiment d'appartenance à une communauté humaine unique partageant un destin commun. Cette thèse examine certains de ces projets, en particulier ceux qui sont menés au sein d’organisations internationales appartenant au système des Nations Unies. Elle démontre que la pratique de la prospective a été, pendant la guerre froide, source de nouvelles conceptions du monde.Les recherches menées se situent à la croisée de plusieurs champs historiographiques dont les trois principaux sont l’histoire du futur, l’histoire intellectuelle transnationale et l’histoire de la globalité. Elles s’articulent autour de la problématique suivante : comment les études sur le futur menées au sein du système onusien pendant la guerre froide ont-elles contribué à faire émerger et à défendre certaines conceptions du global, faisant du futur du monde à la fois une catégorie d’exploration scientifique et une catégorie d’action pour un ensemble d’acteurs internationaux ? / After the Second World War, in particular from the 1960s to the 1980s, several futures studies projects were conducted by international teams. Their goal was to promote the shaping of a « global consciousness » : the sense of belonging to a unique human community sharing a common destiny. This dissertation analyzes some of those projects, particularly those that were conducted within the united nations system. It shows that futurology created new ways of envisioning the world during the Cold War.