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Popular use of the phrase best interests of the child has led many to believe that the meaning and definition of best interests has been thoroughly investigated in the respective sectors working with children. However, research in this area tends to be superficial and generalized and the concept remains inconsistently defined. Article 3 of the United Nations Convention on the Rights of the Child states the best interests of the child is to be a primary consideration in all actions concerning children. There is no straightforward way for the best interests of the child to be systematically studied, understood, or applied if there is not a commonly held or accepted conception of what is in the child’s best interests or measurable standards for those human service executives working with children. The purpose of the study was to identify Saskatchewan human service executives’ insights with respect to the best interests of the child principle as these inform practice, policy, and research in human services and, secondly, to examine their perceptions of moral purpose, agency, and efficacy in the application of the BIC principle, as delineated by the UN Committee in the Concluding Observations on the Combined Third and Fourth Periodic Report of Canada, (United Nations, 2012). A qualitative approach, comprised of general interviews with 11 Saskatchewan human service executives, was used to collect data for this study. Using Hood (2007) and Thomas’ (2006) Generic Inductive Qualitative Method (GIQM) approach for coding, data were categorized from interviews using an inductive approach to developing categories and sub-categories to answer the research questions. Reduced data were interpreted and synthesized by the researcher using extant public documents and literature to triangulate results. Exploration of human service executives’ perceptions in this study revealed a number of insights. Human service executives’ conceptions of the best interests of the child were described in detail and a description of the contemporary Childscape of Saskatchewan emerged. The data revealed that many conceptions of the BIC principle existed and although similarities appeared within sectors, the similarities were mainly due to the sector-specific policies and legislation informing human service. Furthermore, human service executives provided descriptions that add to existing theory about decision making on behalf of the BIC and moral purpose, moral agency, and moral efficacy. Implications for future research entail the adoption of intentional planning, collaboration, and incorporating children’s voice into the processes surrounding the BIC in Saskatchewan in an effort to ensure the future Childscape of Saskatchewan is better than the realities described at the time of this study.

Philosophiae Doctor - PhD / The Platreef is a platinum group elements (PGE) deposit located in the Northern limb of the Bushveld Igneous Complex (BIC). It is a series of mafic and ultramafic sills that are overlain by rocks from the Main Zone (MZ) of the BIC. In comparison to PGE deposits (i.e., Merensky Reef and the UG-2 chromitite) occurring in the Critical Zone (CZ) of the Eastern and Western Limbs of the BIC, which are less than 1 m in thickness, the Platreef is 10 to 400 m in thickness and is comprised of a variety of rocks. PGE mineralisation in the Platreef is not confined to a specific rock type, and its distribution and styles also vary with depth and along strike. Despite the numerous researches that have been conducted, the genesis of Platreef is still poorly understood. New major and trace elements in conjunction with Sr–Nd isotope data, generated from whole-rock analyses of different Platreef rocks, were collected from four drill cores along its strike. The data were examined to determine the source of the magmas and identify the processes involved in its genesis. The study also aimed at establishing whether a genetic link exists between the Platreef magmas and the magmas that formed the Lower Zone (LZ), CZ and MZ in the Rustenburg Layered Suite (RLS) of the BIC. The petrography revealed that the Platreef in the four drill cores consists of harzburgite, olivine pyroxenite, pyroxenite, feldspathic pyroxenite and norite. Based on the textural and modal mineralogy variations, feldspathic pyroxenite was subdivided into five types (I, II, III, IV and V). The variation in the average contents of MgO, LaN/YbN and ΣREE for the Platreef rocks are consistent with the modal mineralogy from the least to the most differentiated rocks. However, the Sr–Nd isotope data of the Platreef rocks have revealed two distinct groups of samples with decreasing ɛNd2060. Group 1 consists of pyroxenite and feldspathic pyroxenite II, III and V having ɛNd2060 values that range from –8.4 to –2.9, and 87Sr/86Sr2060 values from 0.707281 to 0.712106. The Platreef rocks of group 2 consist of olivine pyroxenite and feldspathic pyroxenite Type I with ɛNd2060 ranging from –12.6 to –10.8, and 87Sr/86Sr2060 ranging from 0.707545 to 0.710042. In comparison to the LZ, CZ and MZ rocks, which have ɛNd values ranging from –8.5 to –5.1, and 87Sr/86Sr ranging from 0.704400 to 0.709671, Platreef pyroxenite of group 1 have lower negative ɛNd2060 values (from –3.8 to –2.9) and higher 87Sr/86Sr2060 values from 0.709177 to 0.710492, whereas feldspathic pyroxenite of group 1 have overlapping ɛNd2060 values (from –8.4 to –4.9) but also higher 87Sr/86Sr2060 values (from 0.707281 to 0.712106). Instead, the Platreef olivine pyroxenite and feldspathic pyroxenite in group 2 highly negative ɛNd2060 values and overlapping 87Sr/86Sr2060 values. It is therefore suggested that the Platreef magmas derived from the partial melting of an heterogeneous mantle source comprising depleted mantle melts and both metasomatized slightly unradiogenic Nd enriched melts and highly unradiogenic Nd enriched melts from the subcontinental lithospheric mantle. These magmas ascended via the continental crust using different paths and interacted with rocks of different Sr–Nd isotopic compositions which resulted in the formation the hybrid magmas. The study speculates that sulphide saturation in the Platreef magmas was reached in the staging chambers at depth, and the varying styles of the PGE mineralisation in the Platreef rocks are the result of the varying degree of partial melting of the heterogeneous source for their magmas. In conlusion, this study suggests that the genesis of the Platreef is much more complex and should be considered very much independent from processes involved in the genesis of the RLS in the Eastern and Western Limbs of BIC in agreement with earlier studies. / NRF Inkaba ye Africa Iphakade / 2020-08-31

Given a set of potential explanatory variables, one model selection approach is to select the best model, according to some criterion, from among the collection of models defined by all possible subsets of the explanatory variables. A popular procedure that has been used in this setting is to select the model that results in the smallest value of the Akaike information criterion (AIC). One drawback in using the AIC is that it can lead to the frequent selection of overspecified models. This can be problematic if the researcher wishes to assert, with some level of certainty, the necessity of any given variable that has been selected. This thesis develops a model selection procedure that allows the researcher to nominate, a priori, the probability at which overspecified models will be selected from among all possible subsets. The procedure seeks to determine if the inclusion of each candidate variable results in a sufficiently improved fitting term, and hence is referred to as the SIFT procedure. In order to determine whether there is sufficient evidence to retain a candidate variable or not, a set of threshold values are computed. Two procedures are proposed: a naive method based on a set of restrictive assumptions; and an empirical permutation-based method. Graphical tools have also been developed to be used in conjunction with the SIFT procedure. The graphical representation of the SIFT procedure clarifies the process being undertaken. Using these tools can also assist researchers in developing a deeper understanding of the data they are analyzing. The naive and empirical SIFT methods are investigated by way of simulation under a range of conditions within the standard linear model framework. The performance of the SIFT methodology is compared with model selection by minimum AIC; minimum Bayesian Information Criterion (BIC); and backward elimination based on p-values. The SIFT procedure is found to behave as designed—asymptotically selecting those variables that characterize the underlying data generating mechanism, while limiting the selection of false or spurious variables to the desired level. The SIFT methodology offers researchers a promising new approach to model selection, whereby they are now able to control the probability of selecting an overspecified model to a level that best suits their needs.

In educational research, students often exist in a multilevel social setting that can be identified by students within classrooms, classrooms nested in schools, schools nested in school districts, school districts nested in school counties, and school counties nested in states. These are considered hierarchical, nested, or multilevel because students are within the same community and share similar experiences which have the potential to influence an outcome. Because students within the same classrooms have similar characteristics, conclusions made on these students cannot be independent. To adapt to the hierarchical, multilevel, or nested data structure, multilevel analysis techniques such as hierarchical linear modeling (HLM) can be used to analyze the data. One purpose of HLM is to specify a model that includes appropriate random effects (Guo, 2005). One method which should be considered for inclusion or exclusion of random effects and to evaluate the goodness of fit of the final model to the data is the comparison of models with different specifications of random effects based on Akaike Information Criterion (AIC), Bayesian Information Criterion (BIC) , or Deviance Information Criterion (DIC) which corrects for bias induced by sample size and number of random effects. AIC, BIC, and DIC are information criteria that measure the statistical fit of a model. There has not been any research conducted in the multilevel literature about the impact of sample size and information criteria. This Monte Carlo Monte Carlo simulation compared the influence of sample size on the ability to select the best model in two-level hierarchical models using the information criteria Akaike Information Criterion, Bayesian Information Criterion, and Deviance Information Criterion. Results of this investigation showed that all three information criteria had very low or nonexistent success in choosing the best hierarchical linear model.

Discriminant analysis and random forests are used to create models for classification. The number of variables to be tested for inclusion in a model can be large. The goal of this work was to create an efficient and effective selection program. The first method used was based on the work of others. The resulting models were underperforming, so another approach was adopted. Models were built by adding the variable that maximized new-model accuracy. The two programs were used to generate discriminant-analysis and random forest models for three data sets. An existing software package was also used. The second program outperformed the alternatives. For the small number of runs produced in this study, it outperformed the method that inspired this work. The data sets were studied to identify determinants of performance. No definite conclusions were reached, but the results suggest topics for future study.

The Bushveld Igneous Complex (BIC) is the largest layered mafic intrusion in the world and contains the largest known deposits of vanadium, chromium and Platinum group elements on the planet, as well as large deposits of iron, nickel, copper, tin and fluorite. To aid and improve our understanding of the tectonics that prevailed during the emplacement of the Bushveld Complex relevant data can still be extracted from the metamorphic aureole of the Complex, not the least among which are accurate determinations of pressure conditions during peak metamorphism. A relatively large number of geothermobarometric investigations have been performed on the Bushveld Complex aureole. The summation of all the thermobarometric studies on the Bushveld Complex aureole produces a dataset with largely divergent pressure-estimates, ranging from 1.5 kbar to 5.5 kbar. This study’s main aim was to produce new thermobarometric data for the Eastern Bushveld Complex aureole. To this ends metapelites from the aureole were sampled between Lydenburg and somewhat northwest of Penge. Polished thin-sections were produced for a number of samples and studied under microscope. After XRF analyses were performed on a refined number of samples, pseudosections for these samples were produced using Perplex. Electron microprobe analyses were used to analyze mineral chemistries of five samples and the resultant data used to construct isopleths for these samples in Perplex. The isopleth data was then used to scrutinize and, where possible, refine PT-estimates. The principal results obtained from mineral equilibrium modeling were the pseudosections and isopleths of samples DY09-54 and DY09-56. These samples’ cumulate results suggest that the metapelites of their sampling locality, which lies roughly ~36 km northwest of Penge, reached 530-565 ºC and 2230-2960 bar during peak metamorphism. Modelled isopleths of MnO/(MnO+CaO+FeO+MgO) suggest that these estimates be refined to 550 ± 5 ºC and 2650 ± 20 bar. These pressure estimates agree well with the majority of barometric studies in the literature that post-date the nineteen-eighties. The pressure estimates of 2230-2960 bar suggest that DY09-54 and DY09-56 were at a crustal depth of 7.9-10.4 km during peak metamorphism, assuming that a roughly 1.5 km thick load of rock, mainly of the Rooiberg Group and/or the Lebowa Granite Suite, were situated above the Rustenburg Layered Suite and at the top of the pile that overlay the samples. In such a case the Rustenburg Layered Suite’s contribution to the load would have represented a 4.2-6.7 km thick pile of these mafic rocks and, assuming that the load of Pretoria Group strata in the floor to the Complex had a thickness of 2350 m, the base of the Rustenburg Layered Suite would have been at a crustal depth of 5.6-8.0 km during peak metamorphism and directly above samples DY09-54 and DY09-56. Modelled palaeogeotherms together with the peak-metamorphic crustal depths estimated for samples DY09-54 and DY09-56 suggest that at peak metamorphism the samples’ temperatures had been elevated by no less than 320-355 °C, assuming that no thermal metamorphic effect was active on the samples just prior to the intrusion of the Bushveld Complex. Copyright / Dissertation (MSc)--University of Pretoria, 2012. / Geology / unrestricted

Les talus des routes favorisent la propagation des plantes envahissantes en agissant comme corridors de dissémination ainsi que comme habitats propices à leur établissement et à leur croissance. Le gaillet mollugine (Galium mollugo L., Rubiaceae) est une de ces espèces envahissantes qui utilisent les talus routiers pour étendre leur aire de répartition. Les talus des routes et des pistes cyclables ainsi que les champs en friche du parc national du Bic, dans l'Est du Québec, ont récemment été envahis par le gaillet, ce qui pourrait représenter une menace pour la flore de ce petit parc. Ce mémoire vise à décrire la distribution du gaillet dans le parc, à circonscrire les facteurs qui favorisent la présence ou l'abondance de l'espèce dans les champs en friche et à évaluer son impact sur la richesse et la diversité floristiques. À l'été 2006, 197 quadrats ont été échantillonnés dans les champs en friche du parc pour la caractérisation de leur flore et de leurs particularités physiques et spatiales. La répartition spatiale du gaillet a également été étudiée en bordure des routes, chemins et pistes cyclables du parc ainsi qu'au sein d'un champ en friche. Des modèles de régression logistique ont été élaborés pour déterminer les facteurs qui influencent la présence ou l'absence ainsi que la fréquence d'apparition du gaillet. Des modèles de régression simple ont aussi été construits afin d'étudier l'influence du gaillet sur la richesse et la diversité floristiques. Les modèles montrent que plus la distance qui sépare un site de la route asphaltée la plus proche diminue, plus la probabilité d'y trouver du gaillet en grande quantité augmente. Les talus des routes asphaltées sont nettement plus envahis que ceux des autres types de corridors de transport. Le gaillet a une influence négative à la fois sur la richesse et sur la diversité floristiques. Les talus routiers constituent des habitats propices (milieux bien drainés, conditions très ensoleillées, peu de compétition) pour la plante. La grande quantité de terres en friche qu'on trouve dans le parc national du Bic favorise aussi sa prolifération. Pour freiner, sinon ralentir l'invasion des champs par le gaillet, il serait préférable de ne pas construire de nouvelles routes ou chemins dans le parc et de ne pas asphalter les routes de gravier qui existent déjà. Cela fournirait au gaillet de nouveaux habitats (talus) et corridors de dissémination.

Le travail soumis commence par un aperçu du micro-crédit tel qu’il a été introduit au Bangladesh par M. Yunus. Puis on donne un modèle stochastique des retards de versement. Comme ces retards ne donnent pas lieu à une sanction financière, ils constituent, de fait, une baisse du taux réel de crédit. Ce taux est alors, lui-même, aléatoire. On calcule un taux espéré en fonction de la probabilité de retard de remboursement hebdomadaire. On déduit que ce taux espéré est d’environ 3.5% inférieur au taux (annoncé) du cas déterministe si l’on considère que 3% des retards atteignent 4 semaines. Le travail se poursuit par une étude statistique de données du micro-crédit en Thaïlande. On commence par présenter un modèle de régression logistique du taux de remboursement par rapport aux 23 variables mesurées sur un échantillon de 219 groupes d’emprunteurs. On présente ensuite une sélection des variables les plus pertinentes selon un critère AIC ou BIC par une méthode “backward stepwise”. Finalement des expériences sur des sous-échantillons montrent une bonne stabilité du choix des variables obtenues par la sélection. / This study is inspired from a real scenario of microcredit lending introduced in Bangladesh by Yunus. A stochastic model of random delays in repayment installments is then constructed. Since delays occur without financial penalty, the interest rate is obviously lower than the exact claimed. This rate then becomes a random variable corresponding to the random repayment time, in which simulation results of its distribution are provided. The expected rate is computed as a function of in-time installment probability. It is found around 3.5% lower than the exact one in the deterministic case when considering 3% of delay occurred within four weeks in real practice. The work is extended to a statistical analysis on data of microcredit in Thailand. It is started by presenting a logistic regression model of repayment outcome containing 23 input variables measured on a sample of 219 lending groups. Applying penalized criterion, AIC or BIC together with backward stepwise elimination procedure on the full model, a more parsimonious model kept only most relevant predictors is obtained. Finally, experiments on sub-samples show a stability of the chosen predictors obtained by the selection method.

Dans une forêt du Parc national du Bic, l'activité passée du porc-épic a été reconstituée par une approche dendroécologique, impliquant la datation des cicatrices d'alimentation présentes sur le tronc des pins gris. Cette étude a débuté par la description de la structure de la forêt de pins gris sélectionnée pour l'analyse des cicatrices. Cette forêt provient des feux de forêt de 1847 et 1867 et se compose principalement de deux cohortes de pins gris. L'inventaire des arbres a montré qu'en raison d'une longue période sans feu, la majorité des pins gris présents dans le peuplement sont actuellement morts ou sénescents et les plus jeunes pins gris ont près de 100 ans. Le sapin baumier est l'espèce la plus abondante dans la strate de régénération. Ainsi, en absence de feu la forêt de pins gris sera remplacée par une sapinière. Selon la structure d'âge des cicatrices, l'activité du porc-épic a été particulièrement élevée pendant les années 1980, ce qui concorde avec la création du Parc national du Bic. Avant et après cette période, la fréquentation du site par le porc-épic a été plus faible, principalement au cours des années 1920. La diminution récente du nombre de cicatrices concorde avec le déclin de la population de porcs-épics du Parc national du Bic, telle qu'identifiée par le recensement des tanières actives et la capture d'individus. Il est possible également que la diminution de la population de porcs-épics soit attribuable à une augmentation du nombre de prédateurs dans la région depuis le milieu des années 1980.