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No description available.

Using a state of the art galaxy formation software package, GCD+, we model the formation and evolution of galaxies which resemble our own Galaxy, the Milky Way. The simulations include gravity, gas dynamics, radiative gas cooling, star formation and stellar evolution, tracing the production of several elements and the subsequent pollution of the interstellar medium. The simulations are compared with observations in order to unravel the details of the Milky Way's formation. Several unresolved issues regarding the Galaxy's evolution are specifically addressed. In our first study, limits are placed on the mass contribution of white dwarfs to the dark matter halo which envelopes the Milky Way. We obtain this result by comparing the abundances of carbon and nitrogen produced by a white dwarf-progenitor-dominated halo with the abundances observed in the present day halo. Our results are inconsistent with a white dwarf component in the halo 5% (by mass), however mass fractions of ~1-2% cannot be ruled out. In combination with other studies, this result suggests that the dark matter in the Milky Way is probably non-baryonic. The second component of this thesis probes the dynamical signatures of the formation of the stellar halo. By tracing the halo stars in our simulation, we identify a group of high-eccentricity stars that can be traced to now-disrupted satellites that were accreted by the host galaxy. By comparing the phase space distribution of these stars in our simulations to observed high-eccentricity stars in the solar neighbourhood, we find devidence that such a group of stars - a 'stellar stream' - exists locally in our own Galaxy. Our next set of simulations demonstrate the importance of strong energy feedback from supernova explosions to the regulation of star formation. Strong feedback ensures that the building blocks of galaxy formation remain gas-rich at early epochs. We demonstrate that this process is necessary to reproduce the observed low mass and low metallicity of the stellar halo of the Milky Way. Our simulated galaxy is shown to have a thick disk component similar to that observed in the Milky Way through an abrupt discontinuity in the velocity dispersion-versus-age relation for solar neighbourhood stars. This final study suggests that the thick disk forms in a chaotic merging period during the Galaxy's formation. Our thick disk formation scenario is shown to be consistent with observed properties of the thick disk of the Milky Way.

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No description available.

The opportunity cost of conveyance corridors; highways, hydro lines and pipelines is the monetary value of resource uses foregone; the lost value of physical production resulting from the allocation of land to right-of-way use. Theoretical models were developed for calculating the resource uses foregone and under the criteria of measurability and availability of data, practical equations for conveyance corridors traversing agricultural and forested areas were formulated. Use of practical equations was illustrated by creating hypothetical corridors through the Municipalities of Elton and North Cypress (agricultural application) and through Township 61, Ranges 27 and 28 (forestry application). Conflict between rights-of-way and recreational areas was difficult to quantify and strict economic analysis of opportunity costs was not possible. An alternative technique of reclamation, reparation and mitigation (RRM) was therefore proposed for evaluating opportunity costs. Difficulty in defining wildlife prices and determining the effects of corridors on wildlife prevented the use of the developed economic equation. Thus the alternative technique of RRM was suggested to quantify wildlife opportunity costs. Application of the model produced a comparison of corridor opportunity costs. For a hypothetical corridor, 120 feet wide and 42 miles long traversing agricultural land the highway had a loss of $1, 087,000 and the hydro line with wooden towers a loss of $4000 with steel towers, $13,000. The pipeline had a range of opportunity costs from a benefit of $11,000 to a loss of $127,000. All values were calculated for 50 years, undiscounted. One equation was derived for all corridors in forested areas. Application of this model to a hypothetical corridor, 120 feet wide and 12.6 miles long produced for all corridors, and opportunity cost of $151,000 (calculated for 50 years undiscounted). A questionnaire inquiring about the effects of pipelines on soil productivity was sent (summer 1973) to farmers having a pipeline traversing their property. Nine percent of the respondents indicated an increase in yield due to the pipeline, 25 percent reported no change and 66 percent indicated a decrease in crop yield. However, general lack of data of effects of pipelines on soil productivity suggest the need for further study. Numerous ways are available for reducing opportunity costs of corridors; of which multiple use is one of the best. All land has potential for wildlife utilization and a review of literature suggests that corridors are suitable for wildlife production. Thus where active primary production is not possible or too costly it is recommended that steps be taken to use idle right-of-way lands for wildlife enhancement and production.

No description available.

Thesis (Ph.D.) - Swinburne University of Technology, 2004. / A dissertation presented in fulfillment of the requirements for the degree of Doctor of Philosophy, Swinburne University of Technology - 2004. Typescript. Includes bibliographical references (p. 111-122).

Thesis--Northwestern University, 1968.

Thesis (Ph. D.)--Rhodes University, 1998. / Includes bibliographical references (p. 183-197).