Thesis (M.S.)--University of Wisconsin--Madison, 1966. / eContent provider-neutral record in process. Description based on print version record. Includes bibliographical references.

Thesis (Ph. D.)--University of Washington, 1999. / Vita. Includes bibliographical references (p. 390-402).

Thesis (Ph.D.)--Baylor University, 2006. / Includes bibliographical references (p. 168-171).

Thesis (Ph.D.)--RAND Graduate School, 2007. / Includes bibliographical references.

The concept of reciprocal acoustical travel-time measurements as a means of determining path-averaged currents is well established. We have designed an instrument to exploit this principle in studies of the boundary layer just beneath the arctic ice cover. Such measurements are of interest both because of the opportunity provided for comparison with the more commonly acquired point measurements and because of a particular configuration allowing determination of average vorticity, which cannot be achieved with the traditional approach; in addition, their unprecedented sensitivity allows detection of phenomena not observable with traditional sensors. The acoustical instrument was deployed during the spring of 1989 in the sub-ice boundary layer of the Eastern Arctic in order to measure turbulence, path-averaged horizontal current, and relative vorticity. A triangular acoustic array of side 200 m was used to obtain reciprocal transmission measurements at 132 kHz, at 8, 10 and 20 m beneath an ice floe. Pseudo-random coding and real-time signal processing provided precise acoustic travel time and amplitude for each reciprocal path. Mean current along each acoustic path is proportional to travel time difference between reciprocal transmissions. Horizontal velocity normal to the acoustic paths is measured using scintillation drift. The instrument measures horizontal circulation and average vorticity relative to the ice, at length scales characteristic of high frequency internal waves in the region. The rms noise level of the measurements is less than 0.1 mm/s for velocity measurements and 0.01 for vorticity, averaged over one minute. Except near the mechanical resonance frequency of the moorings, the measurement accuracy is limited by multipath interference. Path-averaged horizontal velocity is compared to point measurements and marked differences are observed due to local anomalies of the flow field. The integral measurement of current is particularly sensitive to the passage of internal waves that have wavelengths longer than the horizontal separation of the transducers. A comparison of horizontal velocity at two depths in the boundary layer shows good coherence at internal wave frequencies and some attenuation as the ice is approached. Relative vorticity at internal wave length scales is dominated by horizontal shear caused by flow interaction with ice topography and not by planetary vorticity. Reciprocal acoustical travel time measurements over paths of several hundred meters can be used to probe the statistical behaviour of turbulent velocity fine structure in the ocean. For homogenous isotropic flows, and for long measuring baselines, an analytic expression relating line-averaged and point measurements of velocity is derived. Anisotropic and inhomogeneous flows are also considered. Correction formulas for the spatial and temporal variability of advection velocity along the measuring baseline are obtained. Practical limitations are established, and experimental data from the arctic boundary layer beneath ice is compared with the theory. A new remote sensing technique for measuring turbulent kinetic energy dissipation rate is suggested. / Graduate

Prior to 1963 no previous vegetation studies had been undertaken in this region of the Low Arctic Subalpine/Foothill Zone of the Canadian Western Arctic, although several studies had been completed in similar regions in Arctic Alaska. This study was initiated in 1965 to obtain quantitative and qualitative data on vegetation and environmental relationships, including soil data for characterization of Low Arctic Subalpine/Foothill Zone soils. With these basic data it was considered possible to analyze, integrate and interpret community and soil relationships and to propose a usable classification system for the recognizable ecosystematic units in this portion of the zone. Initial criteria for selecting communities were based on uniformity and discreteness. Vegetation in each community was studied by the single plot method employing phytosociological techniques of the Zurich - Montpellier School as modified by Krajina (1933). Data on environmental conditions collected for each of 166 communities included degree of slope, profile, pattern of topography, exposure, altitude and wind influence. Coefficients of similarity between communities were computed using the formula 2W/A+B X 100, where A is the sum of all measures (abundance and presence) for one community, B is the sum of all measures for another community, and W is the sum of the lower values for each species which the two communities have in common. To determine the degree of affinity and relative hiatus points between groups of communities cluster analysis using the weighted pair - group method was employed. A two-dimensional dendrogram illustrated the individual plots and succeeding clusters. One soil pit was dug in every analyzed plot to either permafrost, water table, coarse ice shattered parent material or bedrock. A total of 498 soil samples for laboratory analysis were collected from all recognizable horizons. Chemical analyses were undertaken to determine organic matter content, total nitrogen, carbon/nitrogen ratio, absorbed phosphorus, exchangeable calcium, magnesium, potassium and sodium, cation exchange capacity pH. Because soil profiles showed considerable variation the results of the chemical analyses were averaged for the organic, organic - mineral and mineral horizons. On the basis of similarity of species composition six orders, eight alliances, fourteen associations, ten subassociations and thirteen variations were distinguished. The order Betuletalia glandulosae dominated the two study areas, occurring on moderately to well drained mesic to xeric slopes. Community development within this order appeared stable under the present topographic and climatic conditions. The Vaccinio - Betuletum glandulosae closely approximated the climatic climax in mesic habitats. Successional concepts on upper slopes appeared of limited value because communities tended to be discrete. Communities dominant on the lower slopes and in the wetlands were characterized by a narrow active, poor to impeded drainage conditions and more intensive frost action. Classification was more difficult in such areas because communities appeared to be less stable. Successional development in such areas with permanent seepage was toward the Betulo - Eriphoretum vaginati. Snow bed habitats were characterized by the order Petasitetalia frigidii , which was distinguished for the first time in North America, and included the previously undescribed Salicetum chamissonis. Sharp environmental gradients between chionophilous and chionophobous communities suggested that the climate had undergone no significant change in the recent past. Similarities between the Low Arctic Subalpine/Foothill Zone communities and those in other arctic regions, especially Scandinavia, were shown to occur. Twelve soil types were distinguished. In all but two cases each soil type was associated with a particular plant association. A form of podzolization previously described in Arctic Alaska was recognized in the Arctic Brown soils. Gleization, however, appeared to be the major soil forming process in this region of the zone. It was associated with both chionophobous and chionophilous vegetation. In the former, it was favoured by poor drainage, a shallow active layer and intensive frost action; in the latter, it appeared related to materials deposited on the snow that were later incorporated into the soil following snow melt. The high organic content and cation exchange capacity and the low acidity and base saturation were concluded to be important chemical characteristics of these soils. Final results using classification methods showed that the present position of the communities in this region of the Low Arctic Subalpine/Foothill Zone were related to elevation, exposure, soil moisture, thickness of the active layer, duration of snow cover, congeliturbation and topography. / Science, Faculty of / Botany, Department of / Graduate

This is a study of human response to the Arctic and Antarctic environments. It is based on two sources of data: the content analysis of original diaries of polar explorers, and the behavioural evaluation of contemporary crews in polar locations. In the latter, four polar stations were chosen, two in each polar region with a total of fifty-five experimental subjects. Twenty-seven other subjects acted as controls for both polar regions: a northern control group located at a semi-isolated site in Canada, and the southern group located in an Argentinian city. Methods applied in this research included the design and coding of categories which were content analyzed from the original diaries of explorers, and on-site procedures. On-site procedures included psychometric material, participant-observation reports and unstructured interviews. Fifteen behavioural measures within the domain of personality, perception of the environment, affection, social stress and community behaviour were administered. It was hypothesized that the human response would be similar in both polar regions because of environmental and sociological similarities, and that the polar setting would affect men and women in a negative way. Results showed that: (i) the polar environment is not perceived as stressful by the crews - a low anxiety state across both polar regions was found, (ii) traumatic experiences of the explorers had led to the perception of the environment in a negative perspective - yet the winter seemed to be a relaxing phase for the crews rather than stressful, (iii) personnel stationed at polar sites may possess special characteristics which distinguish them from the majority of the population, (iv) although cross-cultural differences exist, they are not as strong as might be anticipated - the environment exerts a unifying influence, (v) differences in gender-response are difficult to assess due to the small number of women subjects, but some differences with controls were noted. / Graduate and Postdoctoral Studies / Graduate

No description available.

No description available.

Ivermectin also called the wonder drug has been used over the years to control internal and external parasites in livestock. In humans it has been used for the control of several neglected tropical diseases. With regards to efforts to control malaria, mass drug administration (MDA) of ivermectin in humans and livestock has been considered as a potential tool. This is due to challenges in malaria preventive strategies such as insecticide resistance in mosquitoes, shift in their behaviors and residual transmission. Ivermectin reduces malaria transmission by targeting the mosquito nervous system resulting in their death. Ivermectin and its metabolites could have great impacts on the environment as well as human and health. In temperate settings, impacts of ivermectin in the environment were studied due to intense use of the drug in livestock. There is also a necessity to study effects of ivermectin in the tropics before MDA for malaria vector control. Despite its great potential, previous studies done recorded toxicity and sensitivity of the drug to most arthropods mainly dung organisms because ivermectin is released in dung at high concentrations for the case of livestock. With dung organism activity being affected the dung decomposition process is disrupted, cattle avoid these grazing areas leading to financial losses. In the tropics where there is a high number of malaria cases, there is no information on the impacts of the drug in the environment. We placed standardized dung pats from ivermectin-treated and control cattle to determine the effect of ivermectin on dung degradation and dung fauna in Tanzania. For the dung degradation study, at 15, 30 and 45 days post placement, we observed a total of 220 dung pats in the field. We measured termite colonization; wet weight of the entire pat; water content; dry weight of the 10 g subsamples and organic matter from subsamples and the whole pat. For the dung fauna study, we collected fresh dung 3, 10 and 29 days post treatment and put the pats out in the field to be colonized by insects before being transferred to emergence traps. We also did a semi field study where we collected dung pats 1,2,3 and 5 days post treatment to obtain larvae counts. We qualitatively assessed insect larvae activity in the field experiment and observed and counted larvae in the semi field study. We found that termites colonized pats from cattle treated with ivermectin more readily compared to controls (p < 0.001). Compared to control pats, the treated pats' wet weight decreased more slowly on day 15 (p < 0.001), day 30 (p < 0.001), and on day 45 (p = 0.037). Percent dry weight increased over time and similarly between the treatments as water content decreased. Organic matter of the 10g sub samples was similar between the treatments. Total organic matter in the whole pats showed significant differences on day 15 (p < 0.001), and day 30 (p = 0.003), but not on day 45 (p = 0.291). Qualitatively, we observed that pats from treated cattle had less insect larvae activity as compared to controls in the field study. In the semi field study, we counted less larvae in the pats from ivermectin-treated cattle than in the control pats (p < 0.001). Our results indicate that ivermectin and its residues affect dung degradation and dung fauna in tropical savanna settings, and the environmental safety may be at risk upon mass drug administration in livestock. / Master of Science in Life Sciences / Ivermectin is a drug commonly used in livestock and humans to control most parasitic infections. Malaria is a disease transmitted by female Anopheles mosquitoes and prevalent in tropical regions mostly the sub-Saharan Africa. There are efforts worldwide to reduce transmission of malaria such as the used of insecticide treated bed nets as well as use of repellents and spraying insecticides indoors. These efforts are challenged by insecticide resistance in mosquitoes, change in mosquito behavior as well as remaining malaria cases after such interventions are applied. With such challenges comes a need to use ivermectin which has the ability to kill mosquitoes. Despite its great potential, evidence from temperate regions record that ivermectin affects the environment by decreasing dung insect activity, affecting the developmental process and causing a delay in dung decomposition. These effects cause cattle to avoid such pasture areas, resulting in an increase in pest pressure and affecting the economy in general. In the tropics where malaria is prevalent and plans are in place to use ivermectin in mass drug administration for mosquito control, there is a need to look at the environmental impact of the drug. We placed 1 kg dung pats from ivermectin-treated and control cattle to determine the effect of ivermectin on dung degradation and dung fauna in Tanzania. For the dung degradation study; at 15, 30 and 45 days after pats were placed in the field, we observed a total of 220 dung pats. We measured termite colonization; wet weight of the entire pat; water content; dry weight of the 10 g subsamples and organic matter from subsamples and the whole pat. For the dung fauna study, we collected fresh dung 3,10 and 29 days post treatment and put the pats out in the field to be colonized by insects before being transferred to emergence traps. We also did a semi field study where pats were collected 1,2,3 and 5 days post treatment to obtain larvae counts. We qualitatively assessed insect larvae activity in the field experiment and observed and counted larvae in the semi field study. We found that termites colonized pats from cattle treated with ivermectin more readily compared to controls, and treated pats' wet weight decreased more slowly. Dry weight of dung increased as water content decreased with no differences between the treatments. Organic matter of the subsamples did not differ in the treatments but the average mass of organic matter of the individual dung pats decreased slower in ivermectin-treated pats. Qualitatively, we observed that pats from treated cattle had less insect larvae activity as compared to controls in the field study. In the semi field study, we counted more larvae in control pats than the ivermectin pats. Our results indicate that ivermectin and its residues affect dung degradation and dung fauna in tropical savanna settings, and the environmental safety may be at risk upon mass drug administration setting.