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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
1

EMPIRICAL AND CONCEPTUAL APPROACHES TO LIFE-HISTORY TRADE-OFFS: THE SIZE AND NUMBER OF OFFSPRING IN BROODS OF A PARASITOID WASP

Saeki, Yoriko 01 January 2012 (has links)
Trade-offs in resource allocation underlie key life history traits of organisms. My dissertation focuses on the size-number trade-off in clonal broods of offspring using the polyembryonic wasp, Copidosoma bakeri parasitizing immature stages of the moth Agrotis ipsilon. I aim to characterize responses of wasp brood size and individual body mass by manipulating the environments in order to understand the allocation pattern in the size number trade-off. In reviewing the functional forms of trade-off relationships in relation to resource constraints, I distinguish among three main trade-off types based on graphical representations of the relationship between the trade-off variables: linear, convex (inverse), and concave. The size-number trade-off in C. bakeri shows convex relationship. Characteristics of the trade-off are sex specific: female broods have larger body mass but smaller brood size than do male broods. When food intake of the host was increased, the trade-off between wasp body mass and brood size for both sexes shifts toward both higher wasp brood size and higher body mass. When the host has better access to food late in development, the size-number trade-off curve moves up and to the right on the graph. However, the trait combinations shift along the same trade-off curve toward greater wasp body mass but smaller brood size when the host development time is shorter due to more resources in early in development. I also investigate temperature effects on the size-number trade-off. C. bakeri brood size significantly increases with high temperature early in host development. There is no shift in the allocation pattern of the size-number trade-off with temperature. Finally, I test effects of body mass on longevity, fecundity, and mating competitiveness of C. bakeri. Larger body size increases female longevity, and mated females produce more eggs than unmated females. There are no significant relationships between male body mass and longevity or mating competitiveness. Mating reduces male longevity independent of body mass. The different impact of body mass on fitness between male and female wasps suggests the observed sex-specific allocation patterns of the size-number trade-off. Implications of the experiments and possible follow-up work are discussed.
2

Lean knowledge life cycle framework to support lean product development

Maksimovic, Maksim January 2013 (has links)
This research thesis presents the development of a novel Lean Knowledge Life Cycle (LeanKLC) framework to support the transformation into a Lean Product Development (LeanPD) knowledge environment. The LeanKLC framework introduces a baseline model to understand the three dimensions of knowledge management in product development as well as its contextualisation with acclaimed LeanPD process models. The LeanKLC framework comprises 23 tasks, each accomplished in one of the seven key stages, these being: knowledge identification, previous knowledge capture, knowledge representation, knowledge sharing, knowledge integration, knowledge use and provision and dynamic knowledge capture. The rigorous research methodology employed to develop the LeanKLC framework entailed extensive data collection starting with a literature review to highlight the gap in the current body of knowledge. Additionally, industrial field research provides empirical evidence on the current industrial perspectives and challenges in managing product development knowledge. This research was part of a European FP7 project entitled Lean Product and Process Development (LeanPPD), which provided the opportunity to involve industrial collaborators in action research to support practical aspects during the LeanKLC framework development. The synthesis with the current LeanPD paradigm is accomplished by demonstrating the LeanKLC stages in two distinct streams related to the development of A3 thinking for problem solving and the development of trade-off curves to facilitate set based design at the conceptual stage. The novel LeanKLC is validated in two case studies providing the industry with detailed insights on real product development applications. In particular this research highlights that the LeanPD knowledge environment is a wide subject area that has not yet been thoroughly understood and that industry engagement in empirical research is vital in order to realise any form of LeanPD transformation.

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