Size-Dependent Transition to High-Dimensional Chaotic Dynamics in a Two-Dimensional Excitable Medium

The spatiotemporal dynamics of an excitable medium with multiple spiral defects is shown to vary smoothly with system size from short-lived transients for small systems to extensive chaos for large systems. A comparison of the Lyapunov dimension density with the average spiral defect density suggests an average dimension per spiral defect varying between three and seven. We discuss some implications of these results for experimental studies of excitable media.Comment: 5 pages, Latex, 4 figure

The influence of ‘topic and resource’ on some aspects of social theorising

Developments in sociological theory since the 1960s have been responses to disciplinary problems rather than changes in fashion. The problem of topic and resource—where sociology has to use everyday understandings and practices as study resources even though they are legitimate topics of enquiry—has been an important and sometimes neglected spur to many of these developments. The turn to discourse, conversation analysis and the rise of Bourdieu's reflexivity are all attempts to address the problem, but each is shown to be unsatisfactory in different ways. In summary, they seek to address the issue as requiring either a principled methodological or a principled theoretical solution, and neither approach is capable of comprehensively addressing the matter. It is argued that these ‘solutions’ depend, in turn, on one of two particular construals of what the ‘problem’ consists in, neither of which is necessary or coherent. Each, it is argued, depends on a philosophical trick: making language out to need formal improvement (the Bertrand Russell trick) or introducing inappropriate scepticism to everyday life (the René Descartes trick). It is suggested that treating topic and resource not as a problem but as something which opens up new areas of investigation successfully deflates the issue and avoids unnecessary theoretical and methodological contortions

Feminist phenomenology and the woman in the running body

Modern phenomenology, with its roots in Husserlian philosophy, has been taken up and utilised in a myriad of ways within different disciplines, but until recently has remained relatively under-used within sports studies. A corpus of sociological-phenomenological work is now beginning to develop in this domain, alongside a longer standing literature in feminist phenomenology. These specific social-phenomenological forms explore the situatedness of lived-body experience within a particular social structure. After providing a brief overview of key strands of phenomenology, this article considers some of the ways in which sociological, and particularly feminist phenomenology, might be used to analyse female sporting embodiment. For illustrative purposes, data from an autophenomenographic project on female distance running are also included, in order briefly to demonstrate the application of phenomenology within sociology, as both theoretical framework and methodological approach

Contestable adulthood: variability and disparity in markers for negotiating the transition to adulthood

Recent research has identified a discreet set of subjective markers that are seen as characterizing the transition to adulthood. The current study challenges this coherence by examining the disparity and variability in young people’s selection of such criteria. Four sentence-completion cues corresponding to four differentcontexts in which adult status might be contested were given to 156 British 16- to 17-year-olds. Their qualitative responses were analyzed to explore patterns whilst capturing some of their richness and diversity. An astonishing amount of variability emerged, both within and between cued contexts.The implications of this variability for how the transition to adulthood is experienced are explored. The argument is made that markers of the transition to adulthood are not merely reflective of the bio–psycho–social development of young people. Rather, adulthood here is seen as an essentially contested concept,located within the discursive interactional environment in which young people participate

When veiled silences speak: reflexivity, trouble and repair as methodological tools for interpreting the unspoken in discourse-based data

Researchers who have attempted to make sense of silence in data have generally considered literal silences or such things as laughter. We consider the analysis of veiled silences where participants speak, but their speaking serves as ‘noise’ that ‘veils’, or masks, their inability or unwillingness to talk about a (potentially sensitive) topic. Extending Lisa Mazzei’s ‘problematic of silence’ by using our performativity-performance analytical method, we propose the purposeful use of ‘unusual conversational moves’, the deployment of researcher reflexivity, and the analysis of trouble and repair as methods to expose taken-for-granted normative frameworks in veiled silences. We illustrate the potential of these research practices through reference to our study on men’s involvement in reproductive decision-making, in which participants demonstrated an inability to engage with the topic. The veiled silence that this produced, together with what was said, pointed to the operation of procreative heteronormativity

Models and metaphors: complexity theory and through-life management in the built environment

Complexity thinking may have both modelling and metaphorical applications in the through-life management of the built environment. These two distinct approaches are examined and compared. In the first instance, some of the sources of complexity in the design, construction and maintenance of the built environment are identified. The metaphorical use of complexity in management thinking and its application in the built environment are briefly examined. This is followed by an exploration of modelling techniques relevant to built environment concerns. Non-linear and complex mathematical techniques such as fuzzy logic, cellular automata and attractors, may be applicable to their analysis. Existing software tools are identified and examples of successful built environment applications of complexity modelling are given. Some issues that arise include the definition of phenomena in a mathematically usable way, the functionality of available software and the possibility of going beyond representational modelling. Further questions arising from the application of complexity thinking are discussed, including the possibilities for confusion that arise from the use of metaphor. The metaphor of a 'commentary machine' is suggested as a possible way forward and it is suggested that an appropriate linguistic analysis can in certain situations reduce perceived complexity

Effect of parasympathetic stimulation on brain activity during appraisal of fearful expressions

Autonomic nervous system activity is an important component of human emotion. Mental processes influence bodily physiology, which in turn feeds back to influence thoughts and feelings. Afferent cardiovascular signals from arterial baroreceptors in the carotid sinuses are processed within the brain and contribute to this two-way communication with the body. These carotid baroreceptors can be stimulated non-invasively by externally applying focal negative pressure bilaterally to the neck. In an experiment combining functional neuroimaging (fMRI) with carotid stimulation in healthy participants, we tested the hypothesis that manipulating afferent cardiovascular signals alters the central processing of emotional information (fearful and neutral facial expressions). Carotid stimulation, compared with sham stimulation, broadly attenuated activity across cortical and brainstem regions. Modulation of emotional processing was apparent as a significant expression-by-stimulation interaction within left amygdala, where responses during appraisal of fearful faces were selectively reduced by carotid stimulation. Moreover, activity reductions within insula, amygdala, and hippocampus correlated with the degree of stimulation-evoked change in the explicit emotional ratings of fearful faces. Across participants, individual differences in autonomic state (heart rate variability, a proxy measure of autonomic balance toward parasympathetic activity) predicted the extent to which carotid stimulation influenced neural (amygdala) responses during appraisal and subjective rating of fearful faces. Together our results provide mechanistic insight into the visceral component of emotion by identifying the neural substrates mediating cardiovascular influences on the processing of fear signals, potentially implicating central baroreflex mechanisms for anxiolytic treatment targets