<p>In the 20th century, where tobacco smoking continues to be the leading preventable cause of death, an alarming number of people continue to smoke, despite awareness of the implications of exposure for themselves and those around them. Campaigns for the promotion of effective tobacco legislation and awareness are continuously being confronted by the tobacco industry's reluctance to put the health of their consumers before company profits, leading to a ripple effect of misinformation, serious health risks and economic implications, at least for the consumers. Pregnant women are especially a concern, because exposure to tobacco smoke affects not only the smoking mother but has serious implications for the health of her unborn child. Therefore, the aim of this study was to investigate the effect of maternal exposure to nicotine during all the phases of lung development, or from the onset of the phase of rapid alveolarisation and, whether copper supplementation will prevent the adverse effects of maternal nicotine exposure, on lung development in the offspring.</p>

Offspring phenotype can be adaptively altered via maternal non-genetic inheritance. Such ‘maternal effects’ enable females to adjust their per offspring investment in response to variation in the offspring environment, and thus maximise their reproductive success. Consequently they play a pivotal role in population dynamics and the response of species to environmental change. Despite this, little is known about how maternal effects mediate reproductive investment in response to multiple or novel environmental changes, such as those driven by anthropogenic activity. I use the 2-spot ladybird intraguild predation system, where resources and predation risk are highly variable, to explore the role of maternal effects in the response of a native species to an invasive predator, as well as answering outstanding questions about how maternal effects function under complex and antagonistic sets of variables. The results indicate that it is unlikely that maternally mediated changes in egg phenotype will improve the survival of 2-spot ladybird offspring in the face of predation from larvae of the invasive harlequin ladybird. They do, however, demonstrate the importance of studying maternal effects in the context of the multiple environmental factors, which more accurately represent the complex environments in which organisms live and evolve, corroborating recent theoretical predictions. Finally I provide evidence of the multifaceted nature of parental effects in aposematic species and reveal the role that they may play in shaping the variation in defence and warning coloration observed in adult populations.

Philosophiae Doctor - PhD / In the 20th century, where tobacco smoking continues to be the leading preventable cause of death, an alarming number of people continue to smoke, despite awareness of the implications of exposure for themselves and those around them. Campaigns for the promotion of effective tobacco legislation and awareness are continuously being confronted by the tobacco industry's reluctance to put the health of their consumers before company profits, leading to a ripple effect of misinformation, serious health risks and economic implications, at least for the consumers. Pregnant women are especially a concern, because exposure to tobacco smoke affects not only the smoking mother but has serious implications for the health of her unborn child. Therefore, the aim of this study was to investigate the effect of maternal exposure to nicotine during all the phases of lung development, or from the onset of the phase of rapid alveolarisation and, whether copper supplementation will prevent the adverse effects of maternal nicotine exposure, on lung development in the offspring. / South Africa

As we navigate in the world around us, previous experience generally prepares us well to deal with most situations. Cognitive control is required in situations that do not afford a rapidly retrieved solution to a current problem. In the laboratory, cognitive control is usually studied in the context of distractor interference tasks with reaction time as the dependent measure. These studies investigate the ability to selective attend to relevant information presented amidst distraction in space. However, we must also attend to relevant information presented amidst distraction in time. A procedure used to study the temporal constraints of selective attention is the attentional blink (AB) task. Here, a modified AB task is utilized to investigate the memorial consequences of engaging in selective attention at one point in time, on the ability to encode new information presented shortly thereafter, with identification accuracy as the dependent measure. This new procedure enables the empirical investigation of the relationship between selective attention and memory processes that are generally studied in isolation. The current research systematically investigated the relative contribution of intentional and automatic influences over selective attention in an AB task, by manipulating the context in which difficult T1 selection trials were presented. The results suggest that contextual influences of control over selective attention occur via a blend of intentional and automatic processes. Whereas intentional processes may be required to establish control settings in novel contexts, once established, control settings can be recruited automatically. These results extend current research on contextual control of selective attention to a novel domain, and consequently, provide insight into the underlying processes that produce the AB effect. Moreover, these results highlight the important role of context-specific learning in the study of cognitive control. Abstract As we navigate in the world around us, previous experience generally prepares us well to deal with most situations. Cognitive control is required in situations that do not afford a rapidly retrieved solution to a current problem. In the laboratory cognitive control is usually studied in the context of distractor interference tasks with reaction time as the dependent measure. These studies investigate the ability to selective attend to relevant information presented amidst distraction in space. However, we must also attend to relevant information presented amidst distraction in time. A procedure used to study the temporal constraints of selective attention is the attentional blink (AB) task. Here, a modified AB task is utilized to investigate the memorial consequences of engaging in selective attention at one point in time, on the ability to encode new information presented shortly thereafter, with identification accuracy as the dependent measure. This new procedure enables the empirical investigation of the relationship between selective attention and memory processes that are generally studied in isolation. The current research systematically investigated the relative contribution of intentional and automatic influences over selective attention in an AB task, by manipulating the context in which difficult T1 selection trials were presented. The results suggest that contextual influences of control over selective attention occur via a blend of intentional and automatic processes. Whereas intentional processes may be required to establish control settings in novel contexts, once established, control settings can be recruited automatically. These results extend current research on contextual control of selective attention to a novel domain, and consequently, provide insight into the underlying processes that produce the AB effect. Moreover, these results highlight the important role of context-specific learning in the study of cognitive control. Abstract As we navigate in the world around us, previous experience generally prepares us well to deal with most situations. Cognitive control is required in situations that do not afford a rapidly retrieved solution to a current problem. In the laboratory cognitive control is usually studied in the context of distractor interference tasks with reaction time as the dependent measure. These studies investigate the ability to selective attend to relevant information presented amidst distraction in space. However, we must also attend to relevant information presented amidst distraction in time. A procedure used to study the temporal constraints of selective attention is the attentional blink (AB) task. Here, a modified AB task is utilized to investigate the memorial consequences of engaging in selective attention at one point in time, on the ability to encode new information presented shortly thereafter, with identification accuracy as the dependent measure. This new procedure enables the empirical investigation of the relationship between selective attention and memory processes that are generally studied in isolation. The current research systematically investigated the relative contribution of intentional and automatic influences over selective attention in an AB task, by manipulating the context in which difficult T1 selection trials were presented. The results suggest that contextual influences of control over selective attention occur via a blend of intentional and automatic processes. Whereas intentional processes may be required to establish control settings in novel contexts, once established, control settings can be recruited automatically. These results extend current research on contextual control of selective attention to a novel domain, and consequently, provide insight into the underlying processes that produce the AB effect. Moreover, these results highlight the important role of context-specific learning in the study of cognitive control. As we navigate in the world around us, previous experience generally prepares us well to deal with most situations. Cognitive control is required in situations that do not afford a rapidly retrieved solution to a current problem. In the laboratory cognitive control is usually studied in the context of distractor interference tasks with reaction time as the dependent measure. These studies investigate the ability to selective attend to relevant information presented amidst distraction in space. However, we must also attend to relevant information presented amidst distraction in time. A procedure used to study the temporal constraints of selective attention is the attentional blink (AB) task. Here, a modified AB task is utilized to investigate the memorial consequences of engaging in selective attention at one point in time, on the ability to encode new information presented shortly thereafter, with identification accuracy as the dependent measure. This new procedure enables the empirical investigation of the relationship between selective attention and memory processes that are generally studied in isolation. The current research systematically investigated the relative contribution of intentional and automatic influences over selective attention in an AB task, by manipulating the context in which difficult T1 selection trials were presented. The results suggest that contextual influences of control over selective attention occur via a blend of intentional and automatic processes. Whereas intentional processes may be required to establish control settings in novel contexts, once established, control settings can be recruited automatically. These results extend current research on contextual control of selective attention to a novel domain, and consequently, provide insight into the underlying processes that produce the AB effect. Moreover, these results highlight the important role of context-specific learning in the study of cognitive control. / Thesis / Doctor of Philosophy (PhD) / Cognitive control refers to our ability to direct our actions in accordance with our goals. Traditionally, the construct of cognitive control was assumed to be synonymous with the construct of free will. In recent years, cognitive psychologists have questioned the volitional nature of cognitive control. Generally speaking, this thesis investigates the following question; to what extent is control over the allocation of our attentional resources governed by our conscious intentions, or, to what extent are such processes recruited automatically? The results suggest that controlled and automatic processes are not dichotomous in nature, but rather, contribute to performance interactively. While conscious intentions may play a role in the establishment of control procedures in novel contexts, once established these control procedures can be brought online automatically. Decisions regarding the need for effortful processing, given the current context, likely shape the construction of these automatized routines.

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This thesis is concerned with the definition of radiobiology by the Medical Research Council (MRC), the state financed medical research funding organisation, in inter-war Britain. It argues that radiobiology was largely .. defined as a specialty by struggles in surrounding fields - particularily radiology, clinical research and the bio-medical sciences. Groups within each of these fields turned to experimental research into the biological effects of radiation to further their attempts to secure an autonomous professional space within medicine, often against resistance from the leaders of medical practice. The MRC was crucial to these attempts, as it provided the first and major systematic research programme into the medical uses and biological effects of radiation during the inter-war years. However, I argue, experimental research was generally subverted to clinical objectives. Indeed, experimentalists themselves were uneasy about clinical domination of their research. However, they were farced into alliance with clinicians partly because they required a medical justification for using the Council's small supply of radium, and partly because the Council's independence in medical research was threatened by the leaders of medical practice. If the Council was not the ideal place to foster experimental research free from clinical interference, the clinicians who dominated it were also opposed to the control of research by the leaders of medical practice, and were generally mare sympathetic towards the bio-medical sciences. Con~equentlYI mast experimental scient~sts sided with these clinicians in order. to protect the Council's independence. Radiobiology reflected the accomodations each side had to make in this alliance.

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published_or_final_version / Physics / Doctoral / Doctor of Philosophy

published_or_final_version / Literary and Cultural Studies / Master / Master of Arts