Southern Africa faced a serious food security crisis after a three-year drought which started in the 1999/2000 season. In 2002, Zimbabwe and its neighbours declared food emergencies. With improved climatic conditions in 2003, Zimbabwe failed to recuperate from the crisis despite its neighbours showing signs of recovery. Instead, the food crisis in Zimbabwe intensified and has threatened the lives of many ordinary Zimbabweans. This paper argues that the land reform programme and its after effects, other government policies, international sanctions and intractable political posturing have all played a significant role in causing and prolonging the post 2000 food crisis in Zimbabwe. International and local food aid became a priority to feed the millions of hungry Zimbabweans. With severe food shortages, food aid became an important political tool used by the main players in the food distribution process to win support or discredit the other side. Drawing from the political theories of famine, this research argues that the food crisis in Zimbabwe is largely due to the failure of political accountability by the government of Zimbabwe, and also by the international relief organizations and other stakeholders who are in and outside Zimbabwe. With a thorough review of primary, secondary and scholarly literature, helped by informal discussions with people living in Zimbabwe, the research found out that the Zimbabwe food crisis has thus far failed to be resolved due to lack of political commitment and competence by the government of Zimbabwe; and an unwillingness by the international community to work with the Mugabe government which many in the west see as a dictatorship.

Population replenishment through recruitment is an essential process for the long term viability of corals and their associated communities, particularly under increasing stresses that threaten their vitality. Although many researchers have identified specific factors that influence individual processes in the early life cycle of corals, few studies to date have attempted to determine the cumulative success of a cohort's progression through these stages in natural reef settings. Specifically, there is a paucity of knowledge regarding appropriate and realistic techniques to forecast the success of recruitment in natural settings, while taking into account both the individual and environmental factors that regulate these recruitment dynamics at local scales. Because of this need, the overall goals of this dissertation research were to (1) assess key life stage processes leading to recruitment - specifically, settlement and early post-settlement processes - for which previous knowledge was limited or absent; and (2) using this knowledge, develop a local-scale recruitment model that assessed the cumulative success of a cohort's progression through all the early life stages and identified those processes that had a strong relative influence on regulating recruitment dynamics. Focusing on the common western Atlantic brooding coral, Porites astreoides, this dissertation research was divided into three main sections to address the overall objectives: (1) identification and quantification of recruitment patterns in natural reef settings, in order to guide the development and testing of the recruitment model (Chapter 2); (2) assessment of the focal species' behaviors, survivorship rates, and factors affecting those rates during its progression through the primary early life stage processes (i.e., basic habitat preferences during the settlement stage, Chapter 3; early post-settlement survivorship, Chapters 4 and 5); and (3) development of a local recruitment model that accounted for the full complement of early life stage processes in a spatially-explicit simulation framework (Chapter 6). While unique study-specific insights were gained from each of the individual chapters, a few general insights emerged with respect to the overarching study objectives from this dissertation research. First, larval supply is a key driver for recruitment, where a high degree of larval loss, either through direct larval mortality or export from the reef, occurs prior to settlement on the substrate. Rates of loss were 96-99% in the model analyses, and as such represent the first major population bottleneck for this species and others with similar life histories. Compounding this larval loss is a second population bottleneck during the early post-settlement stage, where mortality was typically greater than 75% within the first week after settlement. Such high rates of loss have important implications for future population dynamics, as relatively minor changes to these rates of loss can have relatively strong influences on future dynamics. Second, habitat influences on recruitment were found to be relatively minimal when compared to high rates of mortality in both the larval supply and early post-settlement stages. Although the relative influence of habitat may be strong under unique situations where substantial space preemption limits settlement (e.g., high macroalgal cover, sedimentation, or adult coral cover), these effects may not be reflective of average systems. However, the influence of habitat may still be crucial for ensuring that the few individuals who survive the larval supply and the early post-settlement bottlenecks recruit into the future adult population, and these influences may interact with other density-dependent processes as adult cover increases. Overall, this research presents valuable and novel insights on a number of the under-studied early life stage processes. By identifying the key processes which regulate recruitment, this work highlights those stages whose responses to environmental change will have strong impacts on recruitment and subsequent population dynamics. In addition to the process-based insights gained on these dynamics, this work provides informative criteria for managers on the stages most responsive to conservation efforts aimed at promoting resilience and recovery.

Post-release survival of hatchery fishes is imperative to the success of any supplemental stocking program. The purpose of this research was to identify differences between hatchery and wild red drum (Sciaenops ocellatus) and determine if pre-release exposure techniques improve survival of hatchery individuals. Objectives were to contrast survival skills of hatchery and wild red drum from different locations, and examine if exposure to natural stimuli (e.g., habitat, predators, live prey) enhances survival skills in naïve hatchery red drum. Laboratory trials using high-speed videography (250 frames per second, fps) and field mesocosm experiments were used to investigate differences in prey-capture (e.g., attack distance, mean attack velocity, capture time, maximum gape, time to maximum gape, gape cycle duration, and foraging behaviors) and anti-predator performance (e.g., reaction distance, response distance, maximum velocity, time to maximum velocity, mean acceleration, and maximum acceleration) of hatchery and wild red drum. Results indicated that anti-predator performance measures differed significantly between hatchery and wild red drum. Variability in prey-capture and anti-predator performance for hatchery and wild red drum was high (CV range: 5.6 – 76.5%), and was greatest for hatchery fish for the majority of performance variables tested. Exposure to habitat (Spartina alterniflora marsh) did not appear to afford any obvious survival benefits to hatchery red drum, although survival skills did vary according to ontogenetic stage. Hatchery red drum exposed to natural predators (pinfish, Lagodon rhomboides) exhibited significantly greater attack distances during feeding events, and anti-predator performance variables were 20 – 300% in these individuals versus naïve red drum. In predation experiments with free-ranging pinfish predators, mortality rates (Z) ranged from 0.047 – 0.060 h-1 · predator-1; however no significant differences in mortality were found between fish reared with and without predators. Hatchery red drum reared on live prey (Artemia franciscana, mysid shrimp) demonstrated enhanced prey-capture and foraging behaviors as well as anti-predator performance relative to fish reared on artificial (pellet) diets. Findings of this research indicate that several behavioral patterns differed between hatchery and wild red drum; however, these differences can be mediated through the use of various pre-release exposure techniques.

The introduction of sentinel lymph node biopsy (SLNB) has conveyed several new issues, such as the risk of false negativity, long-term consequences, the prognostic significance of micrometastases and whether ALND can be omitted in sentinel lymph node- (SLN) positive patients. Archived SLN specimens from 50 false negative patients and 107 true negative controls were serially sectioned and stained with immunohistochemistry. The detection rate of previously unknown metastases did not differ between the false and the true negative patients. The risk of false negativity was higher in patients with multifocal or hormone receptor-negative tumours, or if only one SLN was found. In a Swedish multicentre cohort, 2216 SLN-negative patients in whom ALND was omitted were followed up for a median of 65 months. The isolated axillary recurrence rate was only 1.0%, and the overall survival was high (93%). The survival of 3369 breast cancer patients (2383 node-negative (pN0), 107 isolated tumour cells (pN0(i+), 123 micrometastases (pN1mi) and 756 macrometastases (pN1)) was analysed. The 5-year cause-specific and event-free survival was worse for pN1mi and pN1 patients than for pN0 patients. There was no difference in survival between pN0(i+) and pN0 patients. Tumour and SLN characteristics in 869 SLN-positive patients were compared between those with and without non-SLN metastases, and the Tenon score was calculated. The risk of non-SLN metastases was higher in case of SLN macrometastases (compared with micrometastases), a high positive/total SLN ratio and Elston grade 3 tumours, and increased with increasing tumour size. The area under the curve (AUC) for the Tenon score was 0.65, and the test thus performed inadequately in this population. In conclusion, despite the risk of false negativity, SLNB with omission of ALND in SLN-negative patients appears to be safe even in the long term. The presence of micrometastases is of prognostic importance and should entail adjuvant treatment. The need for ALND in patients with SLN micro- and even macrometastases has been questioned, but the occurrence of non-SLN metastases is hard to predict, and strong evidence for the safe omission of ALND is lacking.

A common characteristic in neurodegenerative diseases of the brain is death of specific neuronal populations. The lack of neuron proliferation and axon extension in most parts of the central nervous system leads to chronic loss of neurons in the case of injury or disease. Therefore it is essential to identify signals involved in neurogenesis and neuronal survival. A favorable model in which to study these events is the olfactory sensory neurons in the main olfactory epithelium and their target in the glomeruli of the olfactory bulb. In spite of constant regeneration, each olfactory sensory neuron maintain expression of one particular odorant receptor and the specificity of their axonal projections to the glomeruli. Most mammals also have an accessory olfactory system consisting of the sensory neurons in the vomeronasal epithelium and their target area the accessory olfactory bulb. Differential expression of receptors and other genes divides the olfactory and vomeronasal epithelium into zones, but the function and mechanisms underlying the establishment of these zones are still elusive. We identified four genes with graded expression patterns that correlated with the zones of the olfactory epithelium. One of the identified genes encodes a retinoic acid synthesizing enzyme, RALDH-2. We showed that RALDH-2 was expressed in a gradient in cells of the lamina propria underneath the olfactory epithelium, suggesting a possible retinoic acid regulation of zonally expressed genes in the olfactory epithelium. To investigate the role of retinoic acid in the olfactory systems, we generated a transgenic mouse strain that selectively expressed a dominant negative retinoic acid receptor in mature olfactory and vomeronasal neurons. We found that subsequent to the establishment of axonal projections, the neurons of both olfactory systems died prematurely by retrograde caspase-3 activation. In the main olfactory system the onset of apoptosis was associated with the appearance of incorrect heterogenous glomeruli with axons of more than one OR identity. Additionally, the activity regulated cell adhesion molecule kirrel-2 was down regulated suggesting an additional regulation of this gene by retinoic acid. Deficient retinoic acid signaling in olfactory sensory neurons could thus induce apoptosis by changing the parameters for axonal competition by neural activity and kirrel-2 expression. We found evidence for a selective neuronal death in the accessory olfactory system of the dnRAR mice, where only vomeronasal sensory neurons belonging to the basal zone died by retrograde caspase-3 activation. This implies that the two populations of sensory neurons in the vomeronasal epithelium differently depend on retinoic acid for their survival.

<i>Escherichia coli</i> O157 is a food borne pathogen of increasing public health concern worldwide. Cattle have been implicated as the primary reservoir of <i>E. coli</i> O157. The fact that the livestock industry has rapidly expanded in Saskatchewan makes it imperative to have a clear scientific understanding of the prevalence of <i>E. coli</i> O157 in this province as well as its survival in soil under ambient conditions.<p>Longitudinal and point studies were employed to determine the prevalence of <i>E. coli</i> O157 among Saskatchewans cattle. During a 2-year period, 23 feedlot and cattle operations were examined and an overall prevalence of 15.6% was reported. The most important finding was that the prevalence rates were highly dependent on cattle density. All <i>E. coli</i> O157 isolates obtained from this study were characterized by using multiplex PCR, RAPD fingerprinting, a Vero cell cytotoxicity assay and antibiotic susceptibility tests. This characterization revealed a surprisingly highly virulent and heterogenous population of <i>E. coli</i> O157 isolates. <p>Subsequently, the survival characteristics of <i>E. coli</i> O157:H7 ATCC 43894 in sterile soil and manure-amended soil microcosms, as well as in situ under ambient environmental conditions were examined. Findings from this work indicated that desiccation had the most lethal effect on cell viability, whereas nutritionally-rich soils significantly increased survival times of the pathogen population. <p>A final study was designed to examine the survival strategy of hyper- and hypothermally adapted <i>E. coli</i> O157 cells exposed to high and low temperatures, with specific focus on the role of RpoS. Using wild type and its rpoS null allele <i>E. coli</i> O157 strains, in combination with 2D PAGE, It was found that both heat and cold post-acclimation stimulons consisted of two large sub-groups: (i) stress proteins, and (ii) housekeeping proteins. Comparative proteomic analyses revealed that the GroEL/S chaperonin complex and Pnp ribonuclease played a crucial role in growth resumption during high and low temperatures, respectively. Notably, RpoS had no control over key stress proteins in either stress stimulon. RpoS, however, showed a significantly more pronounced role during cold temperatures, where it was seen to regulate key proteins involved in homoeoviscous adaptation as well as various housekeeping proteins of both stress stimulons.

The purpose of this study was to describe how three pupils in the senior room of Wandering Spirit Survival School in Toronto responded behaviorally to the cultural and academic experiences provided. Participant observation was used to collect data for the study during the period of September 10 to November 15, 1981. Information concerning pupil behavior was gathered during: periods of total-class instruction and periods of individual instruction by the regular classroom teacher; individually-assigned task time; class sessions with visiting resource persons; free time; Ojibway and French language instruction; instruction at Winchester Public School; Sacred Circle feasts; and recess. Pupil seatwork was collected and studied. Additional information was obtained through interviews with the three Subjects and with the director.<p>The study was conducted over a period of ten weeks and totalled ninety-seven hours fifty-one minutes of observation time. The Subjects were students in the senior room of Wandering Spirit Survival School, an alternative school for native children in Toronto, and their class consisted of thirteen pupils from grades five to eight. The procedures of this study yielded descriptive data of each Subject's behavior during the various types of activities observed. From the behavioral data, an account described each S's behavior over the ten-week study period, as it occurred in various situations and with various instructors/resource persons.' Frequency of behavior and changes in behavior were noted. The behavior of Ss was also discussed in light of the cultural and academic goals of the school. The data suggested that the school was partially meeting its cultural goals and was failing to meet its academic goals in the case of the three Ss studied.<p>Wandering Spirit Survival School aimed at providing a safe, nonthreatening environment for its pupils. The atmosphere of the school and the cultural activities of the Sacred Circle, feasts, and Ojibway language instruction were found to be useful in creating a sense of pride in being Indian for the three Ss of the study. More could have been done in providing pupils with a knowledge and understanding of native heritage, native history, and contemporary native issues. Although Ojibway language was taught three times a week, the three Ss of the study had not learned to read, write, or speak any of the language during the ten weeks of this study.<p>A second goal of Wandering Spirit Survival School was to prepare pupils academically so that, if they chose, they could successfully continue their education beyond grade eight. Observations suggested that the three Ss of the study were not being academically prepared for high school according to this study. The Ss spent a great deal of class instruction time engaged in other activities: talking, drawing pictures, walking around, playing with articles at their desks, leaving the room Their behavior was the same regardless of who the instructor was. The Ss were most attentive during audio-visual presentations and during lessons involving activity on the part of pupils. However, the teaching done at the school involved, for the most part, the use of textbooks and workbooks.<p>The teacher appeared to hold higher expectations for Jim than for Donald and Agnes. These expectations were reflected in the small amount<br> [Abstract truncated. Pages iv - v missing from thesis.]

The field of survival analysis has experienced tremendous growth during the latter half of the 20th century. The methodological developments of survival analysis that have had the most profound impact are the Kaplan-Meier method for estimating the survival function, the log-rank test for comparing the equality of two or more survival distributions, and the Cox proportional hazards (PH) model for examining the covariate effects on the hazard function. The accelerated failure time (AFT) model was proposed but seldom used. In this thesis, we present the basic concepts, nonparametric methods (the Kaplan-Meier method and the log-rank test), semiparametric methods (the Cox PH model, and Cox model with time-dependent covariates) and parametric methods (Parametric PH model and the AFT model) for analyzing survival data.<p> We apply these methods to a randomized placebo-controlled trial to prevent Tuberculosis (TB) in Ugandan adults infected with Human Immunodificiency Virus (HIV). The objective of the analysis is to determine whether TB preventive therapies affect the rate of AIDS progression and survival in HIV-infected adults. Our conclusion is that TB preventive therapies appear to have no effect on AIDS progression, death and combined event of AIDS progression and death. The major goal of this paper is to support an argument for the consideration of the AFT model as an alternative to the PH model in the analysis of some survival data by means of this real dataset. We critique the PH model and assess the lack of fit. To overcome the violation of proportional hazards, we use the Cox model with time-dependent covariates, the piecewise exponential model and the accelerated failure time model. After comparison of all the models and the assessment of goodness-of-fit, we find that the log-logistic AFT model fits better for this data set. We have seen that the AFT model is a more valuable and realistic alternative to the PH model in some situations. It can provide the predicted hazard functions, predicted survival functions, median survival times and time ratios. The AFT model can easily interpret the results into the effect upon the expected median duration of illness for a patient in a clinical setting. We suggest that the PH model may not be appropriate in some situations and that the AFT model could provide a more appropriate description of the data.

In large-scale peer-assisted live streaming systems with hundreds of online channels, it becomes critically important to investigate the lifetime pattern of streaming sessions to have a better understanding of peer dynamics. Aiming to improve performance of the P2P streaming systems, the goal of this thesis is twofold: 1) for popular channels, we wish to identify superior peers, that contribute a higher percentage of upload capacities and stay for a longer period of time; 2) for unpopular channels, we seek to explore factors that affect the peer instability. Utilizing more than 130 GB worth of run-time traces from a large-scale real-world live streaming system, UUSee, we conduct a comprehensive and in-depth statistical analysis. Using survival analysis techniques, we discover critical factors that may influence the longevity. Based on the Cox regression models we built, we also discuss several interesting insights from our measurement results.

In large-scale peer-assisted live streaming systems with hundreds of online channels, it becomes critically important to investigate the lifetime pattern of streaming sessions to have a better understanding of peer dynamics. Aiming to improve performance of the P2P streaming systems, the goal of this thesis is twofold: 1) for popular channels, we wish to identify superior peers, that contribute a higher percentage of upload capacities and stay for a longer period of time; 2) for unpopular channels, we seek to explore factors that affect the peer instability. Utilizing more than 130 GB worth of run-time traces from a large-scale real-world live streaming system, UUSee, we conduct a comprehensive and in-depth statistical analysis. Using survival analysis techniques, we discover critical factors that may influence the longevity. Based on the Cox regression models we built, we also discuss several interesting insights from our measurement results.