2 resultados para failure analysis strategy

em QSpace: Queen's University - Canada


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The purpose of this research is to investigate the various social, political and economic factors that contributed to Canada’s failure to implement a universal school lunch program during the 1940s. Although Canada developed several other social welfare programs in the post-war period, it remains one of the only industrialized nations that does not provide hot meals to children in elementary or secondary schools. Data from the province of Ontario, a major site of postwar reconstruction and policy-making, has been taken up to inform the broader national discourse on school lunches from the 1940s. National, Ontario provincial and City of Toronto archival records were collected and analyzed according to common themes, in order to identify key barriers that constrained government support of a hot meal program. Archival records were identified using key words, and were limited to materials created between 1930-1952. Analysis suggests that sufficient need for a hot meal program had not been established during the 1940s. Despite misleading nutrition messages, rates of malnutrition and nutrient-related disease were at an all-time low, and many Ontario school boards did not appear to have the necessary infrastructure required to supply all pupils with hot meals. The Canadian government had already employed significant resources to improve existing social security programs by coupling them with health education. This strategy reflected a shift in understanding malnutrition as a knowledge-based problem, as opposed to income-based. This understanding was further reinforced through the moralized dissemination of nutrition information, which placed blame on women for improperly raising their children. Ultimately, the strong uptake of nutrition as a public health issue in Ontario may have limited prospective responses to solutions already utilized in the public health domain, and directed favour away from a universal school lunch program for Canada.

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Successful fertilization depends upon the activation of metaphase II arrested oocytes by sperm-borne oocyte activating factor (SOAF). Failure of oocyte activation is considered as the cause of treatment failure in a proportion of infertile couples. SOAF induces the release of intracellular calcium in oocyte which leads to meiotic resumption and pronuclear formation. Calcium release is either in the form of single calcium transient in echinoderm and amphibian oocytes or several calcium oscillations in ascidian and mammalian oocytes. Although the SOAF attributes are established, it is not clear which sperm protein(s) play such role. Sperm postacrosomal WW binding protein (PAWP) satisfies a developmental criteria set for a candidate SOAF. This study shows that recombinant human PAWP protein or its transcript acts upstream of calcium release and fully activates the amphibian and mammalian oocytes. Interference trials provided evidence for the first time that PAWP mediates sperm-induced intracellular calcium release through a PPXY/WWI domain module in Xenopus, mouse and human oocytes. Clinical applications of PAWP were further investigated by prospective study on the sperm samples from patients undergoing intracytoplasmic sperm injection (ICSI). PAWP expression level, analyzed by flow cytometry, was correlated to ICSI success rate and embryonic development. This study also explored the developmental expression of the other SOAF candidate, PLCζ in male reproductive system and its function during fertilization. Our findings showed for the first time that PLCζ most likely binds to the sperm head surface during epididymal passage and is expressed in epididymis. We demonstrated that PLCζ is also compartmentalized early in spermiogenesis and thus could play an important role during spermiogenesis. Detailed analysis of in vitro fertilization revealed that PLCζ disappears from sperm head during acrosome reaction and is not detectable during sperm incorporation into the oocyte cytoplasm. In conclusion, this dissertation provides evidence for the essential non-redundant role of sperm PAWP in amphibian and mammalian fertilization; recommends PAWP as a biomarker for prediction of ICSI outcomes in infertile couples; and proposes that sperm PLCζ may have functions other than inducing oocyte activation during fertilization.