Les relations entre plantes et herbivores occupent une part importante des travaux concernant le rôle de la biodiversité dans le fonctionnement des écosystèmes. Les effets de la diversité des plantes sur les herbivores et la phytophagie se répartissent le long d’un continuum entre résistance et susceptibilité par association, ces deux concepts décrivant respectivement la réduction ou au contraire l’augmentation des dégâts causés par les herbivores avec la diversité des plantes dans les communautés végétales. Si de nombreux travaux menés dans différents écosystèmes suggèrent que la résistance par association est plus fréquente que la susceptibilité par association, les mécanismes sous jacents restent discutés et semblent dépendre de la plus ou moins grande spécialisation des herbivores et de l’identité des espèces végétales associées. En particulier deux questions se posent : (1) quel est l’effet de la diversité des plantes sur la diversité des insectes, et principalement sur les insectes herbivores ? (2) Quelle composante de la diversité des plantes explique le mieux la résistance et la susceptibilité par association ? La méta-analyse présentée dans cette thèse montre que la diversité des animaux augmente avec la diversité des plantes, quels que soient les écosystèmes et les taxons considérés. Dans le cas des Arthropodes, la richesse spécifique des herbivores est mieux corrélée à la richesse spécifique des plantes que celle des prédateurs. De plus, la diversité des herbivores augmente plus rapidement que la diversité des prédateurs avec la diversité des plantes. Ces observations soulèvent un paradoxe : si la diversité des herbivores augmente avec celle des plantes, comment expliquer les nombreux cas où la phytophagie diminue (résistance par association) ? Cette question a fait l’objet d’une approche expérimentale centrée sur le chêne pédonculé et fondée sur la manipulation de la diversité spécifique et génétique des essences forestières. Il en ressort que ces deux niveaux de diversité ont des effets contrastés sur la phytophagie. Les dégâts causés par les insectes herbivores généralistes tendent à augmenter avec la diversité génétique chez leur hôte (susceptibilité par association), alors que les spécialistes ne répondent pas à la diversité génétique chez le chêne. Au contraire, la diversité spécifique est à l’origine d’une résistance par association pour les herbivores spécialistes mais elle est sans effet sur les généralistes. Un résultat original émerge des travaux présentés dans cette thèse : les effets de la diversité des plantes sur les insectes herbivores et leurs dégâts s’exprimeraient principalement à l’échelle locale – celle d’un arbre et de ses voisins immédiats – au travers de « l’apparence » des arbres, une variable conditionnée par leur taille et celle de leurs voisins. La prise en compte de la spécialisation des insectes herbivores et des différentes composantes de la diversité des arbres contribue donc à une meilleure compréhension des mécanismes impliqués dans la résistance et la susceptibilité par association des forêts mélangées. / Functional and structural consequences of plant diversity on insect communities and herbivoryThe relationship between biodiversity and ecosystem functioning remains a key issue in ecology. In particular it has been suggested that plant species diversity can trigger plant-insect interactions, ranging from associational resistance (higher herbivory in monocultures than in more diverse plant communities) to associational susceptibility (higher herbivory in plant mixtures). Although it is now widely acknowledged that associational resistance is more frequent than associational susceptibility, the underlying mechanisms are still debated and seem to depend on herbivore specialization and plant species identity. To contribute to this debate we addressed two questions: (1) What are the consequences of plant diversity for insect herbivore diversity? (2) Which component of plant diversity better accounts for herbivory? On the basis of a meta-analysis we show in this report that animal diversity significantly increase with increasing plant diversity, regardless of habitats or taxa. In arthropods, herbivores species richness increases more steeply with plant richness than predator richness. This result raises an apparent paradox: if herbivore diversity is positively correlated with plant diversity, why herbivory decreases with increasing plant diversity (associational resistance)? To solve this paradox we developed an experimental approach focused on pedunculate oak and based on the manipulation of tree genetic and species diversity. We showed that generalist and specialist herbivores respond differently to the two levels of tree diversity. Herbivory by generalist herbivores significantly increased with oak genetic diversity (i.e. associational susceptibility) while specialist herbivores did not respond to the genetic diversity of their host tree. Conversely, tree species diversity triggered associational resistance to specialist insect herbivores but had no effect on generalists.  The novelty of this works also lies in the identification of a new mechanism that may account for associational resistance in tree species mixtures: host apparency. More apparent oak trees – those that are taller than their neighbours – are more prone to insect damage. Increasing tree species diversity comes together with higher probability of associating faster growing species (such as pine or birch) than can hide neighbouring oaks, reducing their apparency and then their susceptibility. Our findings suggest that accounting for the diet breadth of insect herbivores and the different components of tree diversity can contribute to a better understanding of the mechanisms leading to associational resistance or susceptibility in mixed forests.

M.A. (Historical Studies) / Since its inception in 1902 the aimof the Mine Workers' Union (MWU) was to protect the interests of the White worker. All the strikes organised by the MWU since 1907 had this mission in mind. The position of the skilled worker has always been at stake in the relationship between the government and the mine authorities due to the importance of the goldmine industry. This relationship has been complicated by the industry's dependence on more expensive skilled labour on the one hand and the availability of much cheaper unskilled Black labour on the other hand. White workers who exclusively represented the skilled labour force obtained guarantees for their position in 1911 when work reservation of certain positions wasgranted legal recognition. At the slightest threat to their security the White workers exhibited political power to the extent that this position was considered not negotiable. The MWU's unique relationship with the National Party since 1948 thus gave unequaled protection to a labour union. Socio-political changes in the RSA, especially in the late 1960's and early 1970's, required essential changes in labour relations. The mine industry has also been drawn into the new labour dispensation during the early eighties when jobs for coloured groups and Black people were brought in parity with jobs previously held by White mineworkers. The new labour dispensation proved to be unavoidable already in 1977. This caused resistance by the White mineworkers who considered the changes as treason by the National Party. They used political opportunities in an effort to maintain the status quo in the party's reforms in labour policy. The process which has been seen as politicising and even as militant petered out towards the end of 1981 when it was realised that the new labour dispensation was irreversible and the MWU in collaboration with the Herstige Nasionale Party were unable to obtain a mandate for amending the new labour policies. The MWU finally turned its back on the National Party when the Conservative Party was established in 1982. This party came into being in protest against the National Party's move away from apartheid. The Conservative Party made provision for white workers' right to self-determination as embodied in the old dispensation; it therefore obviously provided a home for the MWU. This merger between the Conservative party and the MWU which came into being after 1982 heralded a new dispensation for the MWU. It also provided the MWU with a new platform for political activities.

M.Com. (Leadership in Performance and Change) / In August 2012 the South African mining industry was the focus of attention due to an illegal strike at Lonmin Platinum mine that resulted in the police shooting striking employees on 16 August 2012. Thirty-four employees lost their lives on that day. An additional ten people died in violent protests in the build-up to the main shooting incident. This strike period has become widely known as ‘Marikana’. This historical incident illustrates how a single incident within an organisation can have an impact at various levels and affect multiple stakeholders. The main objective of this study was to identify the effect that the Marikana mining incident had on Lonmin (the organisation) and its main stakeholders as well as to identify the effect the stakeholders and Lonmin had on each other. In order to reach these objectives an historical timeline of the sequence of events surrounding the Marikana incident was constructed. The main stakeholders involved in the Marikana incident were then identified, and the relationships and the relative strengths between these stakeholders were mapped. The methodology used in the study was Quantitative Narrative Analysis (QNA) as applied by Franzosi (2010). In particular, the content from English newspaper articles sourced from South Africa and England relating to the Marikana mining incident for the period 1 to 24 August 2012 were reviewed, coded and analysed. All relevant data from the articles were recorded in a manual database, coded according to the semantic triplet of ‘actors’, ‘actions’ and ‘subjects’ (S-V-O) (Franzosi, 1989) and analysed based on QNA principles (Franzosi, 2010). First, a sequence analysis was conducted, identifying the roles (consequences) that the respective actors (stakeholders and subgroupings of stakeholders) enacted as well as the order in which they unfolded. The analysis was used to produce a series of network graphs to visually depict the sequence of events and the respective effects of the sequencing of these events. These graphs take the form of stake maps and visually tell the story of how events unfolded and the effects of these events on all the actors involved ...

L’objectif de ma thèse visait à étudier les processus évolutifs ayant conduit à l’évolution du mode de vie galligène et à rechercher des effecteurs impliqués dans l’induction des galles dans la famille des Gracillariidae (Lepidoptera) avec un accent particulier sur deux espèces, Borboryctis euryae et Caloptilia cecidophora. Nous avons ainsi démontré que ces deux espèces présentent la particularité de posséder un mode de vie intermédiaire entre mineur de feuille et inducteur de galle. Le tissu prolifératif présent dans la mine de B. euryae s’apparente en effet à une galle et les larves de C. cecidophora connaissent une transition du mode de vie mineur de feuille à galligène au cours de leur développement. Des campagnes de terrain ont permis de découvrir de nouvelles espèces de Caloptilia inductrices de galles, et leur étude phylogénétique a montré qu’elles forment un groupe monophylétique. Enfin, exploitant la transition de mode de vie de C. cecidophora ainsi que son contexte phylogénétique, nous avons appliqué une approche de transcriptomique comparative intra- et inter-espèce afin de rechercher des effecteurs candidats impliqués dans la formation de galle. / The aim of my thesis was to study the evolutionary processes that led to the evolution of the gall-inducing lifestyle and to look for effectors involved in the induction of galls in the Gracillariidae family (Lepidoptera) with a particular focus on two species, Borboryctis euryae and Caloptilia cecidophora. We have demonstrated that these two species have a particular intermediate life-style between leaf-miner and gall-inducer. The proliferative tissue in the B. euryae mine is similar to a gall and the larvae of C. cecidophora undergo a transition from leaf-miner to gall-inducer during their development. Field work has uncovered new gall-inducing Caloptilia species, and their phylogenetic study has shown that they form a monophyletic group. Finally, exploiting the transition of feeding habit of C. cecidophora as well as its phylogenetic context, we applied a comparative intra- and inter-species transcriptomic approach to search for candidate effectors involved in gall induction.

The researcher selected a quantitative cross-sectional design to test the concurrent validity of learning potential and psychomotor ability by evaluating the relationships between mining machine operators’ learning potential and psychomotor ability as well as their work safety behaviour. Work safety behaviour was considered indicative of their capability to operate a moving machine. The utilization of measuring instruments capable of measuring their learning potential and psychomotor ability and measuring safety behaviour by means of their safety score cards provided the required measurement data. The study involved a quantitative investigation into the relationship between learning potential and psychomotor ability as independent variables and safety behaviour as dependent variable. De Vos, Strydom, Fouche and Delport (2002, p.79) defined quantitative research as “based on positivism, which takes scientific explanation to be nomothetic. Its main aims are to measure the social world objectively, to test hypotheses and to predict and explain human behaviour. A quantitative study may therefore be defined as an inquiry into social or human problems based on testing a theory composed of variables, measured with numbers and analysed with statistical procedures in order to determine whether the predictive generalization of the theory holds true.” The aim of the study was to determine the learning potential and psychomotor ability of mining machine operators as well as compare the following sub-groups (based on the biographical variables): age, years’ experience, educational level and gender. The respondents’ work safety behaviour was measured and the relationship between the two measures of the independent variables (learning potential and psychomotor ability) and work safety behaviour determined. / Industrial and Organisational Psychology / M.Com. (Industrial and Organisational Psychology)

No description available.

Thesis (LLM. (Development and Management Law)) -- University of Limpopo, 2022 / The study looks into the phenomenon of Black Economic Empowerment in South Africa (B-BBEE) in the mining sector. The newly elected government in South Africa had to deal with the injustices of the past under the apartheid government and had to introduce programmes to help the Historically Disadvantaged South Africans and building the economy. For many years, the mining sector contributed to the South African economy; however, mining operations in South Africa have not given the Historically Disadvantaged South Africans opportunities to participate in the mining industries or partake in the mining sector. The introduction of the Broad-Based Black Economic Empowerment in South Africa aims to promote and provide better opportunities to the previously disadvantaged communities in South Africa. However, it has been reflected that there is a slow transformation in the mining industry and economic participation of the Historically Disadvantaged South Africans in South Africa. The study finds that broad-based black economic empowerment (B-BBEE) policies have had little developmental impact and were not properly implemented in the mining sector. Keywords: Broad-Based Black Economic Empowerment, Affirmative Action, Empowerment and the Mining Sector in South Africa

Objective: To determine if paternal preconception exposure to ionizing radiation through uranium mining increases the risk of congenital anomaly (CA) in offspring. Methods: A population-based matched case-control study was conducted. Cases were infants with CAs recorded in the Canadian Congenital Anomalies Surveillance System and born alive in Ontario 1979-86 (ICD-9 codes 740-759); controls were liveborn infants without CAs identified from Ontario birth certificates and individually matched to cases (case-control file {CCF}). Exposed fathers were identified through the linkage of the CCF to the Mining Master File or the National Dose Registry file, which include those who worked in Ontario uranium mines 1952-1986. For men who linked with a case or control child, radon, gamma and total gonadal doses were estimated for three preconception periods: entire, 3-months and 6-months. Odds ratios were estimated using conditional logistic regression. Results: Linkage of 28,991 uranium miners and 40,482 case-control pairs of fathers and offspring in the CCF identified 431 discordant pairs. There was no evidence of increased risk of a child having a CA if the father was ever a uranium miner before conception of the child (OR=0.89, 95% CI=0.74–1.08). Since gamma radiation (especially during the 6-month preconception period) is more biologically relevant to gonads than radon, further analyses were performed on 117 discordant pairs where data on gamma exposures were available. When ever/never miner, exposed to gamma (yes/no), and gamma dose-response variables were all in the model, there was no ever/never miner effect (OR=1.20, 95% CI=0.85–1.69, p-value=0.30), an inverse association for exposure to gamma (OR=0.42, 95% CI=0.25–0.71, p-value=0.001), but most importantly, there was no statistically significant dose-response relationship between gamma dose during the 6-month preconception period and all CAs (OR=1.15 per loge {mSv+0.01}, 95% CI=0.83–1.59, p-value=0.40). Similarly, no dose-response relationship was observed for exposure to gamma radiation in the 3-month preconception period, or for radon or total gonadal radiation in the 3- or 6-month preconception periods. Conclusion: There was no increased risk of a CA among liveborn children of Ontario uranium miners who were exposed to radon, gamma or total radiation during the 3- or 6-month periods before conception.

Objective: To determine if paternal preconception exposure to ionizing radiation through uranium mining increases the risk of congenital anomaly (CA) in offspring. Methods: A population-based matched case-control study was conducted. Cases were infants with CAs recorded in the Canadian Congenital Anomalies Surveillance System and born alive in Ontario 1979-86 (ICD-9 codes 740-759); controls were liveborn infants without CAs identified from Ontario birth certificates and individually matched to cases (case-control file {CCF}). Exposed fathers were identified through the linkage of the CCF to the Mining Master File or the National Dose Registry file, which include those who worked in Ontario uranium mines 1952-1986. For men who linked with a case or control child, radon, gamma and total gonadal doses were estimated for three preconception periods: entire, 3-months and 6-months. Odds ratios were estimated using conditional logistic regression. Results: Linkage of 28,991 uranium miners and 40,482 case-control pairs of fathers and offspring in the CCF identified 431 discordant pairs. There was no evidence of increased risk of a child having a CA if the father was ever a uranium miner before conception of the child (OR=0.89, 95% CI=0.74–1.08). Since gamma radiation (especially during the 6-month preconception period) is more biologically relevant to gonads than radon, further analyses were performed on 117 discordant pairs where data on gamma exposures were available. When ever/never miner, exposed to gamma (yes/no), and gamma dose-response variables were all in the model, there was no ever/never miner effect (OR=1.20, 95% CI=0.85–1.69, p-value=0.30), an inverse association for exposure to gamma (OR=0.42, 95% CI=0.25–0.71, p-value=0.001), but most importantly, there was no statistically significant dose-response relationship between gamma dose during the 6-month preconception period and all CAs (OR=1.15 per loge {mSv+0.01}, 95% CI=0.83–1.59, p-value=0.40). Similarly, no dose-response relationship was observed for exposure to gamma radiation in the 3-month preconception period, or for radon or total gonadal radiation in the 3- or 6-month preconception periods. Conclusion: There was no increased risk of a CA among liveborn children of Ontario uranium miners who were exposed to radon, gamma or total radiation during the 3- or 6-month periods before conception.

The purpose of this study was to evaluate a programme aimed at equipping adult mine workers in the North-West Province in computer-based skills. The study describes how the use of computers for learning has transformed some of the mine workers in an Own-Time learning environment, where computers were integrated in their learning activities, compared to the Full-Time adult learning environment, which did not present a similar opportunity. The perspective of using a combination of two teaching methodologies in the Adult Education and Training (AET) curriculum provided at this mine sought to minimise the conventional didactic instructional approaches, whereby the facilitator does most of the talking while learners become passive listeners. Activity theory (AT), in tandem with the reviewed literature, was well suited as a theoretical framework for this study, since it takes a developmental view of minds and technological interaction in context. The activity system was used to map how existing work-related practices fitted into each component, which includes the subject, object, rule, community and division of labour. A case study was applied as a guiding design in the study in which seventeen mine workers participated. The computer activity was illustrated from multiple perspectives, using a qualitative approach and associated epistemologies and beliefs regarding the engagement with mediational tools. Boundary crossings, the zone of proximal development, and the eight-step-model from activity theory were used to scrutinise the learners’ beliefs, attitudes, knowledge, practices and contradictions. These important aspects assisted in obtaining data through participant observation, interviews and field notes. To discover patterns, concepts, themes and meanings from the notes and transcripts, data analysis was blended with these aspects. This study demonstrated the use of the above-mentioned methods at appropriate times. Without ideal and effective research methods, the quality of evidence of this study would have suffered and elucidations of connections would have been inadequate. The findings revealed that the AET programme made an impact on the company and on the individual participants, in their homes, their place of work, and their communities. Change in the workers’ performance after attending AET computer-based programmes was noticeable especially regarding their literate and numerate knowledge and skills. Contradictions and disturbances in the AET programme were also identified, and an intervention was proposed to facilitate a computer programme that includes the curriculum components such as mouse skills, keyboarding, data manipulation and desktop publishing. The study proposes that the AET policy needs to cover Own-Time learners, even though their learning is not obligatory, in the same way as it covers the Full-Time learners. A modified activity theory, contextualised for a situation such as that in the mine in question, was contributed in the study. Furthermore, some limitations and recommendations for future research were identified from the findings. The proposed AT for adult learners suggests a new way of exploring the practices of mind and technology interaction for adult learners, incorporating cultural backgrounds, age, language, values and beliefs as well as reflective decision making. / Science and Technology Education / D. Ed. (Comparative Education)