Abstract Habitat selection is a crucial process affecting space use and reproductive success of birds. In this thesis, I investigated spatial and behavioural aspects of nest spacing, brood stage space use, habitat selection and factors affecting reproductive success of breeding common goldeneye (Bucephala clangula) using two large and long-term observational data sets from individually marked females. In the nesting stage, I found that spatial nesting pattern of goldeneye females changed from one year to the next and also between spatial scales. However, increasing aggregation of nesting females decreased nesting success due to increasing rate of nest desertion and nest predation especially at small spatial scale. These results provide evidence of a density-dependent population process in the common goldeneye in terms of association between annual spatial dispersion of nesting females and annual nesting success. In the brood stage, the most important factor affecting habitat selection was the amount of food. However, safe nest sites and food requirements of ducklings were not usually met in the same patch and females with broods adjusted their space-use tactics according to these critical breeding resources. Spatial divergence of these two obligatory resources induced brood movements at various distances shortly after hatching. During movements, broods used different landscape elements such as patches, corridors and matrix in a flexible way without clear fitness consequences in terms of duckling survival. Goldeneye broods suffered heavy losses especially during the early brood stage. Increasing predation risk by northern pike (Esox lucius) decreased survival of young ducklings, but frequent total brood losses suggest that also other factors affected duckling survival. Environmental factors such as temperature or rain were not related to the survival of ducklings.

Doctor of Philosophy / Department of Biology / Brett K. Sandercock / Grasslands are among the most rapidly declining ecosystems in the world. The Flint Hills ecoregion contains one of the largest remaining tracts of tallgrass prairie, but most of the area is managed with high densities of grazing animals and frequent prescribed burns, thereby reducing variation in vegetative structure. A homogeneous landscape leads to lower diversity and abundance of wildlife species, including grassland songbirds. Patch-burn grazing management has been proposed to more closely match the historical interaction between fire and selective grazing by native ungulates. Pastures managed with patch-burn grazing have a greater variety of vegetative structure and plant species composition, and as a result, higher species diversity, abundance, and reproductive success of grassland birds. However, past work has not considered potential effects of regional variation in predation risk and rates of brood parasitism by Brown-headed Cowbirds (Molothrus ater), or annual variation in climatic conditions on the effects of patch-burn grazing management on the reproductive success of grassland songbirds. Over a six year period and at two tallgrass prairie sites, I tested the effects of patch-burn grazing on the reproductive success of three native grassland songbird species, Dickcissels (Spiza americana), Eastern Meadowlarks (Sturnella magna), and Grasshopper Sparrows (Ammodramus savannarum), as well as subsequent effects on the space use, movements, and survival of fledgling Dickcissels. I found only minor effects of patch-burn grazing on the reproductive success of grassland songbirds, supporting previous studies that show that patch-burn grazing does not have negative effects on demographic rates of grassland songbirds. Management regime did not affect densities or territory size of male Dickcissels, but bird densities tended to be higher and territories tended to be smaller on patches within the patch-burn grazing treatment that were burned in the previous year. Thus, patch-burn grazing management might benefit Dickcissel populations by providing higher quality breeding habitat in unburned patches. Last, I found evidence for a potential tradeoff between habitat selection for nests vs. fledglings of Dickcissels in some rangeland management strategies. Parents that realized high reproductive success by nesting in pastures with lower cowbird densities, produced fledglings that faced high rates of depredation by snakes and showed greater movements away from those pastures. Survival rates and movements of Dickcissel fledglings were low, especially during the first week after leaving the nest, which stresses the importance of local habitat conditions. At a larger spatial scale, I tested whether regional differences in habitat structure could drive variation in apparent survival of grassland songbirds. I found that grassland- and shrubland-breeding species had higher estimates of apparent survival than forest-breeding species, contrary to the prevailing viewpoint that birds breeding in dynamic landscapes, such as frequently burned grasslands, should show lower apparent survival than species that breed in woody habitats. The results of my field study show that restoring the historical interaction between fire and grazing on the landscape via patch-burn grazing management could benefit grassland songbirds. Moreover, my dissertation is the first study that tests the effects of patch-burn grazing management on the survival and movements of fledgling Dickcissels, and shows that high cowbird densities can cause a tradeoff between different life-stages. Future conservation efforts should take into account regional variation in species abundance, predator community composition and abundance of Brown-headed Cowbirds when assessing the effects of rangeland management on the demography of grassland songbirds.

No description available.

More Texans are living with HIV infection than ever before. in fact, there has been a 6% increase annually, since 2002. This trend is not a result of increased HIV/AIDS incidence, but rather improving life expectancy of those living with HIV. Due to significant advances in HIV/AIDS testing, prevention, and treatment, individuals with HIV are living longer than ever before. However, throughout the state, the life expectancy of a person infected with HIV/AIDS varies spatially. This study investigates and attempts to explain the spatial distribution of HIV/AIDS survival rates by examining neighborhood socioeconomic characteristics. the results suggest that, contrary to expectation, the lowest survival rates occur, not in extreme poverty areas, but rather in moderate SES areas. Too rich to qualify for free treatments, but not rich enough to afford purchasing such treatments, the middle income living with HIV infection are caught between the cracks. the results provide important input for targeting public health interventions to improve HIV/AIDS survival.

This study explored the experiences and survival strategies of teachers in Zimbabwe in the context of low salaries that were brought by the adoption of the multicurrency system in 2009. The specific objectives were to: (i) examine the main socio-economic challenges that teachers are facing after the dollarization of the economy; (ii) establish how the teachers are coping with the challenges; and (iii) illuminate some of the key areas in which in which government may improve conditions and enhance teachers’ wellbeing so as to retain them in the education sector. To achieve its objectives, the study adopted a qualitative interpretive research paradigm. Data collection entailed conducting in-depth interviews with 20 male and female teachers drawn from primary and secondary schools in high and low density areas of the capital Harare. The objective of the interviews was to explore the coping strategies of the teachers in the post-crisis period. The livelihood framework provided the theoretical and analytical framework for the study. The key thesis of this framework is that there is a direct link between assets and the options people possess in practice to pursue alternative activities that can generate the income level required for survival. The interview guide was thus designed to solicit information of the respondents’ income levels; income-generating activities, expenditure and purchasing patterns, rural-urban ties, social networks, and community participation. The key findings of the study were that: the main socio economic challenges that the teachers are facing after the dollarization of the economy include poor salaries, poor living conditions, poor working conditions, demotivation, and restricted career growth paths and to cope with these challenges, the teachers are using the five identified forms of capital—human, physical, natural, financial, and social— to sustain their livelihoods. However a salient finding was that the teachers generally reduced their expenditure and diversified their sources of income as coping strategies. The study concludes with the following three policy recommendations. First, the government should consider using tangible compensation to improve teachers’ remuneration. Second, the government should also improving infrastructure in educational institutions to ensure that working conditions are conducive for teachers to carry out their work effectively. Third and finally, the government in partnership with organizations that promote children’s rights should mobilize resources that can be used to improve teacher motivation. These could include incentives, accelerated promotions and manpower development. / Mini Dissertation (MSocSci)--University of Pretoria, 2016. / Sociology / MSocSci / Unrestricted

Background: We characterized B-cell non-Hodgkin lymphoma (NHL) cases over ten years at a tertiary children's hospital to contribute to the body of knowledge on pediatric lymphoma in developing countries with a high human immunodeficiency virus (HIV) burden. Methods: A retrospective cohort study using clinical and laboratory records of children newly diagnosed with B-cell NHL from January 2005 to December 2014. Results: Seventy-five children ≤ 15 years were included. The majority had Burkitt lymphoma (n = 61). Twenty-five percent (n = 19) were HIV positive and 16% (n = 12) had concurrent active tuberculosis. Bulky disease was present in 65.7% (n = 46) and 30.1% (n = 22) were classified as Lymphomes Malins B (LMB) risk group C. The five year survival estimates for HIV-negative and HIV-positive children were similar in our cohort: 81% vs. 79% for eventfree survival and 85% vs. 83.9% for overall survival. Of three children with Burkitt lymphoma, HIV and LMB group C, two died within one year. Conclusions: Irrespective of HIV status, the survival of children in our B-cell NHL cohort compares favorably with cure rates in developed nations, although advanced disease remains associated with a poor prognosis. Characterization of childhood NHL cases contributes to accurate risk stratification and tailored treatment.

The aim of the research is the statistical modelling of parametric survival distributions of grouped survival data of long- and shortterm policies in the insurance industry, by means of a method of maximum likelihood estimation subject to constraints. This methodology leads to explicit expressions for the estimates of the parameters, as well as for approximated variances and covariances of the estimates, which gives exact maximum likelihood estimates of the parameters. This makes direct extension to more complex designs feasible. The statistical modelling offers parametric models for survival distributions, in contrast with non-parametric models that are used commonly in the actuarial profession. When the parametric models provide a good fit to data, they tend to give more precise estimates of the quantities of interest such as odds ratios, hazard ratios or median lifetimes. These estimates form the statistical foundation for scientific decisionmaking with respect to actuarial design, maintenance and marketing of insurance policies. Although the methodology in this thesis is developed specifically for the insurance industry, it may be applied in the normal context of research and scientific decision making, that includes for example survival distributions for the medical, biological, engineering, econometric and sociological sciences. / Dissertation (PhD (Mathematical Statistics))--University of Pretoria, 2002. / Mathematics and Applied Mathematics / unrestricted

This study determines the influence of causation versus effectuation on entrepreneurial firm survival in high and low dynamism industries. Causation approaches a problem with the end in mind while effectuation’s point of departure is the means. Causal logic predicts a best case future scenario and then gathers the necessary resources to realize that scenario. This is contrasted by effectual logic that attempts to “control” the future by making use of the resources in hand (and those that can be borrowed) while trying to achieve the best possible result. The study consists of a means analysis testing for firm survival in highly dynamic industries per “pure” causal or effectual approach and of a variance analysis, testing for survival as a function of the mixed use of causation and effectuation in both high and low dynamism industries. The product of the means analysis indicates that only two entrepreneurs out of a cohort of 1771 follow a “pure” causal or “pure” effectual approach. As a result of this finding the incidence of “pure” causal or effectual approaches in either high or low dynamism industries is negligible. The output from the variance analysis indicates that causation is a significantly better predictor of entrepreneurial survival than effectuation in both high and low dynamism industries at a 99% confidence level. Below is a summary of the survival probabilities for both high and low dynamism industries across the causal/effectual decision spectrum.This study determines the influence of causation versus effectuation on entrepreneurial firm survival in high and low dynamism industries. Causation approaches a problem with the end in mind while effectuation’s point of departure is the means. Causal logic predicts a best case future scenario and then gathers the necessary resources to realize that scenario. This is contrasted by effectual logic that attempts to “control” the future by making use of the resources in hand (and those that can be borrowed) while trying to achieve the best possible result. The study consists of a means analysis testing for firm survival in highly dynamic industries per “pure” causal or effectual approach and of a variance analysis, testing for survival as a function of the mixed use of causation and effectuation in both high and low dynamism industries. The product of the means analysis indicates that only two entrepreneurs out of a cohort of 1771 follow a “pure” causal or “pure” effectual approach. As a result of this finding the incidence of “pure” causal or effectual approaches in either high or low dynamism industries is negligible. The output from the variance analysis indicates that causation is a significantly better predictor of entrepreneurial survival than effectuation in both high and low dynamism industries at a 99% confidence level. Below is a summary of the survival probabilities for both high and low dynamism industries across the causal/effectual decision spectrum. Copyright / Dissertation (MBA)--University of Pretoria, 2010 / Gordon Institute of Business Science (GIBS) / unrestricted

An ever-changing world and environment demands on organizations ability to adapt. Research shows that organizations that can respond adaptively to change have a greater chance of surviving. This study aimed to identify and account for factors in organizational culture that are seen as adaptive. The study was carried out through a qualitative narrative literature study where 11 articles in different research fields were examined. The study identified factors that characterized an adaptive organizational culture. These factors were flexibility, risk-taking, innovation, creativity and openness to change. The study also reports on appropriate strategies and desirable conditions for creating an adaptive organizational culture where the organization is adaptable in relation to its environment. Examples of that are the importance of establishing commitment, involvement, trust, internal adaption and common purpose, when implementing an adaptive organizational culture. Furthermore the role of leadership and the significance of the organizational structure are discussed in relation to adaptive organizational culture. Despite the results of this study, there is a complexity in assessing an adaptive organizational culture and the field requires more research.

Eighty-three (21M, 62F) of 194 black bears captured during 1994-1996 were equipped with radio collars. Annual survival rates estimated with Kaplain-Meier staggered entry approach for radio collared adult females, adult males, subadult females, and subadult males were 95.3, 100.0, 90.4 and 50.0% respectively. Hunting, handling, vehicle collisions, and natural causes accounted for 81.0, 11.1, 3.2, and 1.6% of mortality. Twenty, 9.8, and 70.6 % of bears harvested were harvested in the deer firearm season, the deer archery season, and the bear firearm season, respectively. Twenty-three cubs were equipped with expandable radio collars (11M,10F) or transmitters implanted subcutaneously (2M,0F) in 1995-1996. Six cubs (4M, 2F) died, 6 (3M,3F) survived their first year, and the status of 11 cubs (6M, 5F) was unknown. Survival rates (date marked until 4 December) estimated with Kaplain-Meier and Heisey-Fuller were 64.3 and 64.7% respectively. Interval survival rates were 71% (15 March to 31 May), 100% (1 June to 31 July), 92% (1 August to 31 August), and 100% (1 September to 4 December). Intraspecific aggression (33.3%), starvation (16.7%), unknown causes (16.7%) and predation (16.7%) were the causes of mortality. Total home range size for males and adult, subadult, and transitional age females were 7.2, 5.5, 5.6 and 7.2 km2 (95% MCP) and 11.2, 6.8, 9.0, and 10.0 km2 (95% normal kernel). Females with cubs had larger fall ranges than spring and summer ranges. Seasonal ranges of solitary females did not differ when estimated with MCP. Bears exhibited home range overlap among and within sex classes. / Master of Science