In the last 150 years, the City of Yellowknife has transitioned from an area of traditional subsistence living to the largest city in the Northwest Territories (Canada) due to the economic influence of resource extraction. As resource extraction in the area boomed, large quantities of pollutants from mine tailings and emissions from roaster stacks adjacent to gold mines were deposited on the landscape, leaving a known legacy of elevated surface water, sediment, and soil metal(loid) concentrations. Most of the research to date has focused on arsenic in the region, and my thesis expands the body of knowledge to include other metal(loids) of interest, including antimony, lead, and mercury. My thesis's main objective was to determine the spatial and temporal extent of legacy mining emissions near Yellowknife and assess the associated biological risk from these historic emissions. I analyzed select intervals from 20 lake sediment cores for time constrained metal(loid) contaminants of concern. I used a combination of paleotoxicity and paleoecotoxicology methods to establish a spatial and temporal footprint of biological risk associated with historic gold mining activities in the Yellowknife region. I determined that lakes close to the mine exhibited a low-level hazard to aquatic communities before mining, while the onset of mining increased the hazard posed by sediments deposited to acute levels. I also discovered that lakes within 5 km of Giant Mine exceeded guideline values for sedimentary mercury during active mining. Further, I developed methods in paleoecotoxicology that indicated a concordance between time deposited, estimated risk, and observed mortality of native Daphnia sp exposed to time-constrained sediment archives. My thesis demonstrates that paleotoxicity and paleoecotoxicology are effective methods to separate historic and modern influences of industrial development on aquatic biota. Additionally, my research has application extensions for policymakers, remediation scientists, Indigenous Peoples, and those proposing new industrial ventures.

京都大学 / 0048 / 新制・課程博士 / 博士(医学) / 甲第20264号 / 医博第4223号 / 新制||医||1021(附属図書館) / 京都大学大学院医学研究科医学専攻 / (主査)教授 椛島 健治, 教授 松田 秀一, 教授 羽賀 博典 / 学位規則第4条第1項該当 / Doctor of Medical Science / Kyoto University / DFAM

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This study employed a stated choice experiment survey to identify southeastern U.S. farmers’ preferences for contracts to produce Giant Miscanthus. We developed a more theoretically consistent framework which takes into account risk preference and perception information and also accounts for heterogeneous status-quo alternatives. Results from our Random Parameter Logit model indicated that price per ton of harvested Giant Miscanthus, biorefinery harvest, and establishment cost-share all had significant positive effects on the probability of a producer accepting a contract to produce Giant Miscanthus, whereas contract length had a significant negative effect. Our analysis also found evidence of significant preference heterogeneity in producers’ preferences for biorefinery harvest, yield insurance, and contract length. We also found that incorporating risk perception and risk preference information, as well as accounting for heterogeneous status-quo alternatives in the decision framework improved overall model performance even though the respective individual coefficients for these variables were not statistically significant.

Star formation is a complex hierarchical process that witnesses the transfer of mass among a range of scales from large diffuse molecular clouds to crowded clumps and finally down to prestellar cores. The final stage of this process has prestellar cores actively accreting matter while undergoing gravitational collapse on their way to becoming main sequence stars. This thesis presents multi wavelength submillimeter observations of the Perseus molecular cloud using 160 μm, 250 μm, 350 μm, and 500 μm maps of thermal dust emission from the Herschel space observatory. Additionally C18O J = 3 → 2 spectral line emission is observed in four star forming clumps within Perseus using the James Clerk Maxwell Telescope. Spectral line emission allows for the separation of material along the line of sight. Prestellar core mass is derived from observational maps using various source finding algorithms. The mass is overestimated when compared to prestellar core mass found from spectral line data. This overestimation can be mitigated with careful selection of source finding algorithm and background removal. Further, the prestellar core mass derived from spectral line data was the closest match to the initial stellar mass function over dust maps. However, both the spectral line masses and dust map masses do not agree with the IMF confirming a star forming efficiency factor in the evolutionary step between prestellar core and main sequence star. Lastly, a filamentary analysis finds that high mass stars preferentially form in crowded regions close to, or contained within, filament structure. / Thesis / Master of Science (MSc) / Star formation is a complex hierarchical process that witnesses the transfer of mass among a range of scales from large diffuse molecular clouds to crowded clumps and finally down to prestellar cores. The final stage of this process has prestellar cores actively accreting matter while undergoing gravitational collapse on their way to becoming main sequence stars. This thesis presents multi wavelength submillimeter observations of the Perseus molecular cloud using 160 μm, 250 μm, 350 μm, and 500 μm maps of thermal dust emission from the Herschel space observatory. Additionally carbon monoxide spectral line emission is observed in four star forming clumps within Perseus using the James Clerk Maxwell Telescope. Spectral line emission allows for the separation of material along the line of sight. Prestellar core mass is derived from observational maps using various source finding algorithms. The mass is overestimated when compared to prestellar core mass found from spectral line data. This overestimation can be mitigated with careful selection of source finding algorithm and background removal. Further, the prestellar core mass derived from spectral line data was the closest match to the initial stellar mass function over dust maps. However, both the spectral line masses and dust map masses do not agree with the IMF confirming a star forming efficiency factor in the evolutionary step between prestellar core and main sequence star. Lastly, a filamentary analysis finds that high mass stars preferentially form in crowded regions close to, or contained within, filament structure.

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Introduction: Below knee amputation is the safest treatment for aggressive benign and malignant bone tumours of the distal tibia yielding good oncological and functional results. However, in selected patients where limb salvage is feasible and amputation unacceptable to the patient, limb salvage using a distal tibial replacement (DTR) can be considered. This study aims to present the oncological and functional results of the use of this treatment method in our unit. Patients & Methods: A retrospective folder review was performed for all 10 patients who received a modular distal tibial replacement between 01/01/2005 and 31/01/2019 for a primary bone tumour either benign aggressive or malignant. Six were female and the mean age was 31 (1275) years. There were five patients with giant cell tumour of bone, four with osteosarcoma and one with a low-grade chondrosarcoma. The patients with osteosarcoma had neo-adjuvant chemotherapy before surgery. Function was assessed by the Musculoskeletal Tumor Society (MSTS) score. Results: There were six females and four males, with a mean age of 31 (12-75) years. Two patients had local recurrence treated with a BKA and one other patient died of metastases three years postoperatively. At a mean follow-up of three years, the remaining eight patients had a mean MSTS score of 83% (67–93%). There were no radiological signs of loosening, and no revision surgeries. Conclusion: Endoprosthetic replacement of the distal tibia for primary bone tumours can be a safe treatment option in very selected cases.