Characterization of Bone Material Properties and Microstructure in Osteogenesis Imperfecta/Brittle Bone Disease

Osteogenesis imperfecta (OI) is a genetic disorder primarily associated with mutations to type I collagen and resulting in mild to severe bone fragility. To date, there is very little data quantifying OI cortical bone mechanics. The purpose of this dissertation was to investigate bone microstructure, mineralization, and mechanical properties in adolescents with OI. Characterization studies were performed on small osteotomy specimens obtained from the extremities during routine corrective surgeries. Nanoindentation was used to examine the longitudinal elastic modulus and hardness at the material level for mild OI type I vs. severe OI type III. Both modulus and hardness were significantly higher (by 7% and 8%, respectively) in mild OI cortical bone compared to the more severe phenotype. Lamellar microstructure also affected these properties, as the younger bone material immediately surrounding osteons showed decreased modulus (13%) and hardness (11%) compared to the older interstitial material. A high resolution micro-computed tomography system utilizing synchrotron radiation (SRµCT) was described and used to analyze the microscale vascular porosity, osteocyte lacunar morphometry, and bone mineral density in OI vs. healthy individuals. Vascular porosity, canal diameter, and osteocyte lacunar density were all two to six times higher in OI cortical bone. Osteocytes were also more spherical in shape. Finally, three-point bending techniques were used to evaluate the microscale mechanical properties of OI cortical bone in two different orientations. Elastic modulus, flexural yield strength, ultimate strength, and crack-growth toughness were three to six times higher in specimens whose pore structure was primarily oriented parallel vs. perpendicular to the long bone axis. There was also a strong negative correlation between the elevated vascular porosity of OI cortical bone and its elastic modulus, flexural yield strength, and ultimate strength. This relationship was independent of osteocyte lacunar density and tissue mineral density. In summary, these findings highlight new material and microstructural changes within OI cortical bone that help contribute to its fragility. They also underscore a deep connection between bone structure and mechanical integrity at multiple length scales

Prairie Dogs and Livestock in Rangeland Systems: Balancing Biodiversity and Production in the Northern Mixed-Grass Prairie

A major constraint of beef production within the Standing Rock Reservation has been identified as a reduction in rangeland quality due in large part to wide-scale colonization by black-tailed prairie dogs (Cynomys ludovicianus). The desire exists within the community to design a holistic framework which incorporates livestock management with the goal of increasing production and rangeland health while still maintaining increased diversity associated with prairie dogs. Prairie dogs reduce the carrying capacity of cattle on rangelands by up to 50% on occupied hectares through direct consumption of vegetation and waste due to clipping to improve detection of predators. Livestock stocking rates that do not account for the level of prairie dog occupation can result in a reduction in animal performance and a further decrease in rangeland productivity due to overgrazing. Research is needed to understand season-long use of grazing cattle on and off prairie dog towns to better inform land manager decisions aimed at reducing over-utilization of grasslands and allowing higher production of livestock. This dissertation study was part of a larger study that was conducted in northcentral South Dakota from 2012 to 2016. This dissertation sub-study was designed to evaluate the impact of prairie dogs and cattle on plant community production and composition, and to determine impacts of colonization on livestock grazing behavior, diet quality, and forage intake. Three pastures with varying levels of prairie dog occupation (0%, 20%, and 40%) were studied. Pasture stocking rates were adjusted to account for the level of forage removed by prairie dogs (50%) on active colonies. Two study treatments were evaluated: Ecological Site (n=3) and grazing treatment (n=4). Ecological sites (ES) were Shallow Loam, Loamy, and Thin Claypan. Grazing treatments included two in off-town locations (non-graze (NG) and cattle only graze (CG)) and two in ontown locations (cattle and prairie dog graze (CPD), and prairie dog only graze (PD)). These treatments and their interactions were evaluated to determine their effects on vegetation (e.g. standing crop, diversity, species richness, etc.) and livestock (e.g. animal weight gains, diet quality and quantity, etc.) parameters. Goals of the dissertation herein are to understand 1) the interactions of prairie dogs and livestock on plant communities and 2) the impact of prairie dog occupation on livestock production. Objectives of this dissertation are: 1) Evaluate plant community response to grazing on and off prairie dog towns to determine how livestock and prairie dogs alter plant community production and composition; 2) Develop strategies that enable identification of plant communities of interest on and off prairie dog towns using remote sensing techniques ; 3) Develop methods to utilize programming tools for efficient processing of GPS collar data ; 4) Evaluate relationships between plant communities and cattle grazing locations to identify patterns and trends in livestock grazing behavior throughout the growing season; 5) Evaluate diet nutrient composition and intake by cattle on plant communities on- and off-town over the grazing season; 6) Develop a framework of cattle nutrient consumption in pastures with varying levels of prairie dog occupation; and 7) Synthesize existing research and results from this dissertation to explore potential synergism between prairie dogs and cattle on the landscape from a systems approach. Vegetation analyses show a significant difference in standing crop biomass between grazing treatments, with sites grazed only by cattle having 36% more biomass than those grazed only by prairie dogs. Plant community data suggest that prairie dogs have a greater impact on production and species composition compared to cattle; percent composition of C3 grasses was greatest off-town, whereas percent composition of C4 grasses was greatest on-town. An invasive C3 species of concern in the Northern Great Plains, Kentucky bluegrass, was almost non-existent on-town, but increased substantially off-town over the 5 years of the study for all ES; the most dramatic increase occurred on the Thin Claypan ES. Species diversity was not different between grazing treatments, however species richness was generally greatest on-town. Additionally, for the entire duration of the study (2012-2016), 46 species were only observed on-town and 17 only observed off-town out of a total 113 species observed throughout the 5 years of the study. The remote sensing analyses show that Random Forest (RF) models were highly effective at predicting different vegetation types associated with on and off prairie dog town locations (misclassification rates \u3c 5% for each plant community). However, comparisons between the predicted plant community map using separate years indicate 6.7% of pixels on-town and 24.3% of pixels off-town changed class membership depending on the year. The results show that while RF models may predict with a high degree of accuracy, transition zones between plant communities and inter-annual differences in rainfall may cause instability in fitted models. An essential component of evaluating livestock behavior for this study was accomplished using GPG collars that record both location and activity. Traditional methods of hand-processing of GPS data require a large number of steps which are both time consuming and prone to errors. As part of this dissertation, methods were created to streamline the processing of livestock GPS collar data, resulting in a technical note publication. Due to the open source nature of Program R, custom functions can be created to merge GPS collar data, GIS data layers, and behavior algorithms to improve data processing efficiency. Plant communities of interest for the livestock behavior and intake components of this study were identified as grass-dominated on-town sites (PDG), forb-dominated ontown sites (PDF), and grass dominated off-town sites (NPD). Livestock behavior analyses from this study show cattle slightly prefer grazing on prairie dog towns, with shifts occurring to off-town locations over the duration of the grazing season. Crude protein (CP) content from diet samples for PDF sites were significantly greater than for PDG and NPD sites. Little difference in many of the diet metrics existed, however, between grass dominated sites (PDG and NPD). Despite higher CP content on forb dominated sites on-town (PDF), intake levels were depressed on these communities due to high bare ground and low vegetation production. Individual livestock performance (average daily gains) averaged over the entire length of the study, were 0.74 kg. /day for the 0% occupied pasture, 0.86 kg. /day for the 20% occupied pasture, and 0.85 kg. /day for the 40% occupied pasture. Reduced stocking rate in prairie dog pastures may have contributed to greater individual animal performance. Higher livestock performance for the prairie dog pastures is potentially due to access to a more diverse diet. Reduced stocking rates in prairie dog pastures, however, resulted in a reduction in overall livestock production in terms of kg / ha. At low levels of colonization in pastures, livestock may potentially benefit from increased diet selection, however, reduction in plant biomass on town may negate any potential gains at higher levels of colonization. The results from this study were combined to take a systems approach to understanding the impacts and interactions of prairie dogs and livestock on plant communities, and the impacts of prairie dog occupation on livestock production in northern mixed-grass prairie ecosystems. Our results indicate that having both on-town and off-town plant communities within a pasture can increase biodiversity and heterogeneity at broader landscape scales. Differences in plant community composition may increase diet diversity for grazing livestock, potentially benefiting individual animal gains, provided forage quantity is not limited. At low levels of colonization, livestock production may only be minimally impacted while still realizing benefits to biodiversity

Aspects of the impact of apartheid on commerce and industry in the Western Cape, 1960 to 1990

Includes abstract.Includes bibliographical references (leaves 147-155).The thesis considers the economic performance of South Africa, from the substantial and sustained growth from 1960 to 1974, followed by a period when the South African economy weakened. The Western Cape economy was not reliant on mining, but had a more stable economy relying on agriculture, property and financial services, and later in the period developed high-tech service industries. Business in South Africa suffered punitive rates of tax to pay for the country's apartheid policies. The establishment of the Bantustans as a homeland for the black ethnic groups was a cornerstone of the National Party policy and the cost burden was enormous with the provision of all the trappings of full nationhood. The job reservation policies, which reserved skilled occupations created a skill shortage in the country and towards the end of the period by necessity the policy 'frayed at the edges'. Western Cape business also suffered the impact of the coloured labour preference policy, which was designed to prevent the movement of blacks to the Western Cape

Mapping the mosaic: Travel writers and the construction of urban imaginaries of Prague and Breslau, 1700-1914

From the early 18th century to the beginning of World War One, travel writers from Western Europe and North America interacted with and sustained a genre of travel writing that imposed legibility and external schemes of order on Central European cities like Prague and Breslau. By simplifying or ignoring complex populations, environments and ongoing processes of change in these cities, Western travel writers collectively created imaginary constructions of Prague and Breslau that diverged from these historical urban spaces in ways that reveal travel writers\u27 prejudices and the ideological scaffolding that underpins travel writing as a genre. This argument makes an important contribution to historians\u27 understanding of the objectivity of travel narratives as source material and to the larger question of the empirical limits outsiders experience when encountering foreign environments