Seed companies have developed novel weed control technologies to combat herbicide-resistant (HR) weeds based on the use of new genetically-modified (GM) crop cultivars and auxin herbicide formulations. These herbicides can variably affect the growth and yield of susceptible cotton even at low concentrations depending on growth stage at exposure. As such, research was conducted in each of two locations in Mississippi in 2014, 2015, and 2016 to determine the cotton growth stage most susceptible to injury and yield effects from simulated misapplications of sub-lethal 2,4-D or dicamba concentrations. Results indicate that generally a decrease in yield partitioned on lower nodes and inner positions was accompanied by a compensatory increase in yield partitioned on vegetative branches and aborted terminals. However, the magnitude of these yield effects differed based on growth stage at exposure and based on which herbicide was used.

Field studies were conducted to test three application methods for applying antagonistic herbicide combinations: 1) tank mix (TMX), 2) mix-in-line (MIL), and 3) separate boom (SPB). Sethoxydim applied with bentazon, glyphosate applied with dicamba or 2,4-D, and clethodim applied with dicamba or 2,4-D had higher efficacy when applied using the SPB method. Antagonism of all the herbicide combinations above was observed when applied using the TMX and MIL methods. In some cases, antagonism was avoided when using the SPB method. Three application methods tested in greenhouse studies were 1) TMX, 2) synthetic auxin applied first (AAF), and 3) synthetic auxin applied second (AAS). The AAS application method resulted in higher weed control than the TMX and AAF methods. Analysis done through liquid chromatography mass spectrometry supported the greenhouse results with higher rates of glyphosate detected with the AAS method.

Ionisable pesticides can be partially ionised within the range of natural soil pH and this strongly influences their reactivity in soils. This group includes important, worldwide contaminants of groundwater and surface waters. It is essential that their specific behaviour is recognised within risk assessment procedures. Experiments were carried out with ten pesticides (six acids and four bases) and nine arable soils (range in pH, texture and organic matter content) to advance the understanding and prediction of the behaviour of ionisable pesticides in soils. The main conclusions can be summarised as follows:<br />• Adsorption of ionisable pesticides tends to be stronger in soils with lower pH and containing more organic carbon. A regression equation including Log D (lipophilicity corrected for pH), the soil organic carbon content and a pesticide descriptor was selected to predict the adsorption of acids. The behaviour of bases was more complex and approaches specific to each compound seem to be required.<br />• There were some marked differences between the soils in their ability to degrade the different ionisable pesticides. The lack of consistent behaviour renders a global approach to prediction of degradation unrealistic. Distinct types of behaviour could however be distinguished according to the main route of degradation.<br />• Significant correlations between sorption and degradation were only observed for three pesticides out of ten, with faster degradation in soils with stronger sorption.<br />• A centrifugation technique was used to measure adsorption at realistic soil moisture contents and provides a robust characterisation of the fraction of pesticide available for leaching. Time-dependent adsorption was also assessed.<br />The increase in adsorption between one and seven days was not directly related to the level of adsorption although it was more important in soils containing more organic carbon.<br />Although specific interactions between pesticides and soils are still not fully understood, these results provide the basis for a more robust analysis of the behaviour of ionisable pesticides in the environment.

Uncertainty is pervasive in risk assessment. In ecotoxicological risk assessments, it arises from such sources as a lack of data, the simplification and abstraction of complex situations, and ambiguities in assessment endpoints (Burgman 2005; Suter 1993). When evaluating and managing risks, uncertainty needs to be explicitly considered in order to avoid erroneous decisions and to be able to make statements about the confidence that we can place in risk estimates. Although informative, previous approaches to dealing with uncertainty in ecotoxicological modelling have been found to be limited, inconsistent and often based on assumptions that may be false (Ferson & Ginzburg 1996; Suter 1998; Suter et al. 2002; van der Hoeven 2004; van Straalen 2002a; Verdonck et al. 2003a). In this thesis a Generalised Linear Modelling approach is proposed as an alternative, congruous framework for the analysis and prediction of a wide range of ecotoxicological effects. This approach was used to investigate the results of toxicity experiments on the effect of 2,4-Dichlorophenoxyacetic Acid (2,4-D) formulations and 4-Chlorophenol (4-CP, an associated breakdown product) on Daphnia carinata. Differences between frequentist Maximum Likelihood (ML) and Bayesian Markov-Chain Monte-Carlo (MCMC) approaches to statistical reasoning and model estimation were also investigated. These approaches are inferentially disparate and place different emphasis on aleatory and epistemic uncertainty (O'Hagan 2004). Bayesian MCMC and Probability Bounds Analysis methods for propagating uncertainty in risk models are also compared for the first time. For simple models, Bayesian and frequentist approaches to Generalised Linear Model (GLM) estimation were found to produce very similar results when non-informative prior distributions were used for the Bayesian models. Potency estimates and regression parameters were found to be similar for identical models, signifying that Bayesian MCMC techniques are at least a suitable and objective replacement for frequentist ML for the analysis of exposureresponse data. Applications of these techniques demonstrated that Amicide formulations of 2,4-D are more toxic to Daphnia than their unformulated, Technical Acid parent. Different results were obtained from Bayesian MCMC and ML methods when more complex models and data structures were considered. In the analysis of 4-CP toxicity, the treatment of 2 different factors as fixed or random in standard and Mixed-Effect models was found to affect variance estimates to the degree that different conclusions would be drawn from the same model, fit to the same data. Associated discrepancies in the treatment of overdispersion between ML and Bayesian MCMC analyses were also found to affect results. Bayesian MCMC techniques were found to be superior to the ML ones employed for the analysis of complex models because they enabled the correct formulation of hierarchical (nested) datastructures within a binomial logistic GLM. Application of these techniques to the analysis of results from 4-CP toxicity testing on two strains of Daphnia carinata found that between-experiment variability was greater than that within-experiments or between-strains. Perhaps surprisingly, this indicated that long-term laboratory culture had not significantly affected the sensitivity of one strain when compared to cultures of another strain that had recently been established from field populations. The results from this analysis highlighted the need for repetition of experiments, proper model formulation in complex analyses and careful consideration of the effects of pooling data on characterising variability and uncertainty. The GLM framework was used to develop three dimensional surface models of the effects of different length pulse exposures, and subsequent delayed toxicity, of 4-CP on Daphnia. These models described the relationship between exposure duration and intensity (concentration) on toxicity, and were constructed for both pulse and delayed effects. Statistical analysis of these models found that significant delayed effects occurred following the full range of pulse exposure durations, and that both exposure duration and intensity interacted significantly and concurrently with the delayed effect. These results indicated that failure to consider delayed toxicity could lead to significant underestimation of the effects of pulse exposure, and therefore increase uncertainty in risk assessments. A number of new approaches to modelling ecotoxicological risk and to propagating uncertainty were also developed and applied in this thesis. In the first of these, a method for describing and propagating uncertainty in conventional Species Sensitivity Distribution (SSD) models was described. This utilised Probability Bounds Analysis to construct a nonparametric 'probability box' on an SSD based on EC05 estimates and their confidence intervals. Predictions from this uncertain SSD and the confidence interval extrapolation methods described by Aldenberg and colleagues (2000; 2002a) were compared. It was found that the extrapolation techniques underestimated the width of uncertainty (confidence) intervals by 63% and the upper bound by 65%, when compared to the Probability Bounds (P3 Bounds) approach, which was based on actual confidence estimates derived from the original data. An alternative approach to formulating ecotoxicological risk modelling was also proposed and was based on a Binomial GLM. In this formulation, the model is first fit to the available data in order to derive mean and uncertainty estimates for the parameters. This 'uncertain' GLM model is then used to predict the risk of effect from possible or observed exposure distributions. This risk is described as a whole distribution, with a central tendency and uncertainty bounds derived from the original data and the exposure distribution (if this is also 'uncertain'). Bayesian and P-Bounds approaches to propagating uncertainty in this model were compared using an example of the risk of exposure to a hypothetical (uncertain) distribution of 4-CP for the two Daphnia strains studied. This comparison found that the Bayesian and P-Bounds approaches produced very similar mean and uncertainty estimates, with the P-bounds intervals always being wider than the Bayesian ones. This difference is due to the different methods for dealing with dependencies between model parameters by the two approaches, and is confirmation that the P-bounds approach is better suited to situations where data and knowledge are scarce. The advantages of the Bayesian risk assessment and uncertainty propagation method developed are that it allows calculation of the likelihood of any effect occurring, not just the (probability)bounds, and that the same software (WinBugs) and model construction may be used to fit regression models and predict risks simultaneously. The GLM risk modelling approaches developed here are able to explain a wide range of response shapes (including hormesis) and underlying (non-normal) distributions, and do not involve expression of the exposure-response as a probability distribution, hence solving a number of problems found with previous formulations of ecotoxicological risk. The approaches developed can also be easily extended to describe communities, include modifying factors, mixed-effects, population growth, carrying capacity and a range of other variables of interest in ecotoxicological risk assessments. While the lack of data on the toxicological effects of chemicals is the most significant source of uncertainty in ecotoxicological risk assessments today, methods such as those described here can assist by quantifying that uncertainty so that it can be communicated to stakeholders and decision makers. As new information becomes available, these techniques can be used to develop more complex models that will help to bridge the gap between the bioassay and the ecosystem.

Pour respecter les droits d'auteur, la version électronique de cette thèse a été dépouillée de certains documents visuels. La version intégrale de la thèse a été déposée à la Division de la gestion des documents et des archives. / Au cours de son histoire, la salle de cinéma s’est érigée à partir d’une politique d’épuration sensorielle, elle-même héritée d’une longue tradition, faisant de l’expérience spectatorielle cinématographique une expérience de contemplation purement audiovisuelle. Cependant, lorsqu’elle traverse une période de crise, tant économique qu’intermédiale, la salle de cinéma renoue avec un modèle attractionnel, polysensoriel et plus particulièrement tactile, lié au cinéma des origines et à ses premiers lieux de diffusion, mais réprimé lors de l’institutionnalisation du média et de sa stabilisation dans la salle consacrée. Aux États-Unis, c’est notamment le cas autour de 1930, au moment de l’arrivée du cinéma parlant et de la Grande Dépression, de même qu’au cours des années 1950, alors qu’une importante compétition intermédiale liée à l’arrivée de la télévision et couplée à des changements démographiques majeurs affecte les exploitants de salles. C’est de nouveau le cas depuis les années 2000, la déferlante numérique et les possibilités de visionnement à domicile arrachant de plus en plus de spectateurs aux salles. Cette thèse propose l’examen approfondi d’une période et d’un cas exemplaires. Elle analyse précisément le moment où les salles américaines connaissent une baisse de fréquentation majeure au cours des années 1950. Pendant cette période apparaissent plusieurs technologies audiovisuelles, mais également de nombreux gimmicks polysensoriels. Or, ces derniers ne sont qu’une version radicale et matérialisée d’idéaux attractionnels portés par les producteurs et l’industrie cinématographique de l’époque aux États-Unis, ce que démontre l’étude du gimmick tactile Percepto, développé en 1959 par le cinéaste William Castle pour accompagner son film The Tingler. Bien au-delà du simple gadget promotionnel, le dispositif Percepto fait vibrer les sièges et hurler les spectateurs, les sollicitant par une sensation physique directe censée prolonger l’univers du film à même la salle de cinéma. Cette expérience cinématographique singulière valorise en outre le caractère à la fois collectif et participatif du visionnement en salle. À la jonction de plusieurs champs théoriques, soit l’histoire culturelle des sens, l’archéologie des médias et les études de diffusion, cette thèse cherche à mettre au jour le rôle majeur des sens pourtant dits « mineurs », notamment celui du toucher, dans l’histoire de la salle de cinéma américaine, et à resituer la tactilité dans les origines attractionnelles du cinéma, en démontrant de quelle manière le corps du spectateur est, par le biais de stratégies polysensorielles, de nouveau inclus dans l’expérience du cinéma, alors qu’il en est traditionnellement exclu. Par ailleurs, elle vise à réinscrire les gimmicks au sein de l’historiographie du cinéma en général et de celle des salles en particulier, tout en faisant découvrir un dispositif cinématographique tactile jusqu’ici généralement méconnu et oublié par la recherche savante : Percepto. Pour ce faire, la thèse s’appuie sur plusieurs sources de première main et propose l’analyse des éléments suivants : le film The Tingler, le fonctionnement du gimmick, les publicités produites autour du dispositif, son apparition en salles, ainsi que sa réception critique et populaire. / Throughout its history, the movie theater has emerged from politics of sensory purification inherited from a long tradition, making the cinematographic spectatorial experience one of a purely audiovisual contemplation. When going through a period of crisis, be it economic or intermedial, the movie theater reconnects with an attractional, multi-sensory and mainly tactile model linked to the origins of cinema and to its first exhibition spaces, but repressed at the time of the institutionalization of the media and its stabilization in the dedicated theater. In the United States, this is notably the case around 1930 with the arrival of talking pictures and the Great Depression, as well as during the 1950s when significant intermedial competition resulting from the advent of television, coupled with major demographic shifts, affects theater exhibition. This has also been the case since the early 2000s, when the digital surge and the possibilities of home viewing have torn more and more spectators away from theaters. This thesis offers an in-depth examination of an exemplary period and case. It analyzes precisely when American theaters experienced a major drop in attendance during the 1950s. During this period, several audiovisual technologies appeared, along with many multi-sensory gimmicks. However, the latter are only a radical and materialized version of ideals of attractions carried by the producers and the film industry of the time in the United States, as demonstrated by the study of the Percepto tactile gimmick, developed in 1959 by filmmaker William Castle to complement his film The Tingler. Far beyond a simple promotional gadget, the Percepto device makes the seats vibrate and the audience scream, addressing the spectators with a direct physical sensation supposed to extend the fictional world of the film right into the theater. This unique cinematographic experience also underlines both the collective and participatory qualities of theatrical viewing. At the junction of several theoretical fields, namely the cultural history of the senses, media archeology and exhibition studies, this thesis seeks to bring to light the major role of the so-called “minor” senses, in particular that of the touch, in the history of the American cinema, and to restore tactility in relation to the attractional origins of cinema, by demonstrating how the spectator's body is, through multisensory strategies, included again in the experience of cinema although it is traditionally excluded. In addition, it aims to re-establish gimmicks within the historiography of cinema as a whole and that of movie theaters in particular while revealing a tactile cinematographic device largely unknown and forgotten by scholarly research to this day: Percepto. To achieve this, the thesis offers the analysis of the following aspects, based on several primary sources: the film The Tingler, the functioning of the gimmick, the advertisements produced around the device, its theatrical release and exploitation as well as its critical and popular reception.

The South African education system is in crisis; with low matric pass rates, high dropout rates, teacher strikes, rising pregnancy rates among teenaged learners, and assaults by learners on educators and other learners. The system is unable to cope with the multiple demands placed on it and a number of NGOs are stepping in to aid the system. This study is an evaluation of an NGO aimed at developing learners through the application of the Appreciative Inquiry approach. The Appreciative Inquiry approach is a method for generating change within an organisation by looking at what works in the organisation and facilitating active participation. The main findings from this study were that the programme seems to have positively affected learners‟ performance both academically and behaviourally; the programme was perceived to have raised the general standard of academic performance at the school. / Psychology / M.A. (Psychology)

Text in Afrikaans, abstract in English / Writer investigates the constitutionality of section 18(4)(d) of the Child Care Act 74 of 1983 against the backdrop of the South African common law and the common law of comparative legal systems. In the South Africa law the mother of an illegitimate child has guardianship. The natural father does not have parental power which weakens his legal position. In analysing the judgement of the Constitutional Court, writer criticises the court for stating that in the case of a newborn baby the kind of discrimination which section 18( 4 )( d) authorises against a natural father may be justifiable in the initial period after the child is born. The constitutional position of the natural father in American jurisprudence is discussed at length. Writer concludes that the natural father has to take positive steps to vest a right to be heard in an adoption application. Proposals for legal reform are also made. / Private Law / LL. M. (Law)

The South African education system is in crisis; with low matric pass rates, high dropout rates, teacher strikes, rising pregnancy rates among teenaged learners, and assaults by learners on educators and other learners. The system is unable to cope with the multiple demands placed on it and a number of NGOs are stepping in to aid the system. This study is an evaluation of an NGO aimed at developing learners through the application of the Appreciative Inquiry approach. The Appreciative Inquiry approach is a method for generating change within an organisation by looking at what works in the organisation and facilitating active participation. The main findings from this study were that the programme seems to have positively affected learners‟ performance both academically and behaviourally; the programme was perceived to have raised the general standard of academic performance at the school. / Psychology / M.A. (Psychology)

Text in Afrikaans, abstract in English / Writer investigates the constitutionality of section 18(4)(d) of the Child Care Act 74 of 1983 against the backdrop of the South African common law and the common law of comparative legal systems. In the South Africa law the mother of an illegitimate child has guardianship. The natural father does not have parental power which weakens his legal position. In analysing the judgement of the Constitutional Court, writer criticises the court for stating that in the case of a newborn baby the kind of discrimination which section 18( 4 )( d) authorises against a natural father may be justifiable in the initial period after the child is born. The constitutional position of the natural father in American jurisprudence is discussed at length. Writer concludes that the natural father has to take positive steps to vest a right to be heard in an adoption application. Proposals for legal reform are also made. / Private Law / LL. M. (Law)