Reasoning about timeouts

In real-time programming a timeout mechanism allows exceptional behaviour, such as a lack of response, to be handled effectively, while not overly affecting the programming for the normal case. For. example, in a pump controller if the water level has gone below the minimum level and the pump is on and hence pumping in more water, then the water level should rise above the minimum level within a specified time. If not, there is a fault in the system and it should be shut down and an alarm raised. Such a situation can be handled by normal case code that determines when the level has risen above the minimum, plus a timeout case handling the situation when the specified time to reach the minimum has passed. In this paper we introduce a timeout mechanism, give it a formal definition in terms of more basic real-time commands, develop a refinement law for introducing a timeout clause to implement a specification, and give an example of using the law to introduce a timeout. The framework used is a machine-independent real-time programming language, which makes use of a deadline command to represent timing constraints in a machine-independent fashion. This allows a more abstract approach to handling timeouts.

Reasoning about deadlines in concurrent real-time programs

We propose a method for the timing analysis of concurrent real-time programs with hard deadlines. We divide the analysis into a machine-independent and a machine-dependent task. The latter takes into account the execution times of the program on a particular machine. Therefore, our goal is to make the machine-dependent phase of the analysis as simple as possible. We succeed in the sense that the machine-dependent phase remains the same as in the analysis of sequential programs. We shift the complexity introduced by concurrency completely to the machine-independent phase.

An investigation into children’s inductive reasoning strategies:What drives the development of category induction?

In a series of studies, I investigated the developmental changes in children’s inductive reasoning strategy, methodological manipulations affecting the trajectory, and driving mechanisms behind the development of category induction. I systematically controlled the nature of the stimuli used, and employed a triad paradigm in which perceptual cues were directly pitted against category membership, to explore under which circumstances children used perceptual or category induction. My induction tasks were designed for children aged 3-9 years old using biologically plausible novel items. In Study 1, I tested 264 children. Using a wide age range allowed me to systematically investigate the developmental trajectory of induction. I also created two degrees of perceptual distractor – high and low – and explored whether the degree of perceptual similarity between target and test items altered children’s strategy preference. A further 52 children were tested in Study 2, to examine whether children showing a perceptual-bias were in fact basing their choice on maturation categories. A gradual transition was observed from perceptual to category induction. However, this transition could not be due to the inability to inhibit high perceptual distractors as children of all ages were equally distracted. Children were also not basing their strategy choices on maturation categories. In Study 3, I investigated category structure (featural vs. relational category rules) and domain (natural vs. artefact) on inductive preference. I tested 403 children. Each child was assigned to either the featural or relational condition, and completed both a natural kind and an artefact task. A further 98 children were tested in Study 4, on the effect of using stimuli labels during the tasks. I observed the same gradual transition from perceptual to category induction preference in Studies 3 and 4. This pattern was stable across domains, but children developed a category-bias one year later for relational categories, arguably due to the greater demands on executive function (EF) posed by these stimuli. Children who received labels during the task made significantly more category choices than those who did not receive labels, possibly due to priming effects. Having investigated influences affecting the developmental trajectory, I continued by exploring the driving mechanism behind the development of category induction. In Study 5, I tested 60 children on a battery of EF tasks as well as my induction task. None of the EF tasks were able to predict inductive variance, therefore EF development is unlikely to be the driving factor behind the transition. Finally in Study 6, I divided 252 children into either a comparison group or an intervention group. The intervention group took part in an interactive educational session at Twycross Zoo about animal adaptations. Both groups took part in four induction tasks, two before and two a week after the zoo visits. There was a significant increase in the number of category choices made in the intervention condition after the zoo visit, a result not observed in the comparison condition. This highlights the role of knowledge in supporting the transition from perceptual to category induction. I suggest that EF development may support induction development, but the driving mechanism behind the transition is an accumulation of knowledge, and an appreciation for the importance of category membership.

Chronic illness in non-heterosexual contexts: towards a critical LGBTQ health psychology

In this thesis, I contribute to the expansion of lesbian, gay, bisexual, trans and queer (LGBTQ) psychology by examining chronic illness within non-heterosexual contexts. Chronic illness, beyond the confines of HIV/AIDS, has been a neglected topic in LGBTQ psychology and sexual identity is often overlooked within health psychology. When the health of lesbian, gay and bisexual (LGB) people has been considered there has been an over-reliance on quantitative methods and comparative approaches which seek to compare LGB people?s health to their heterosexual counterparts. In contrast, I adopt a critical perspective and qualitative methods to explore LGBTQ health. My research brings together ideas from LGBTQ psychology and critical health psychology to explore non-heterosexuals? experiences of chronic illness and the discursive contexts within which LGB people live with chronic health conditions. I also highlight the heteronormativity which pervades academic health psychology as well as the „lay? health literature. The research presented in this thesis draws on three different sources of qualitative data: a qualitative online questionnaire (n=190), an online discussion within a newsgroup for people with diabetes, and semi-structured interviews with 20 LGB people with diabetes. These data are analysed using critical realist forms of thematic analysis and discourse analysis. In the first analytic chapter (Chapter 3), I report the perspectives of LGB people living with many different chronic illnesses and how they felt their sexuality shapes their experiences of illness. In Chapter 4, I examine heterosexism within an online discussion and consider the ways in which sexuality is constructed as (ir)relevant to a diabetes support forum. In Chapter 5, I analyse LGB people?s talk about the support family and partners provide in relation to their diabetes and how they negotiate wider discourses of gender, sexuality and individualism. In Chapter 6 I explore how diabetes intersects with gay and bisexual men?s sex lives. In the concluding chapter, I discuss the contributions of my research for a critical LGBTQ health psychology and identify some possible areas for future research.