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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
361

Ruling out the 'bad things' : how physicians make meaning of persistent unexplained illness in children

Varga, Stefanie January 2008 (has links)
This was a study of physicians' narratives regarding their medical experiences with children with persistent medically unexplained physical illness. The goal was to better understand those attitudes and beliefs that are involved in the construction of meaning regarding the child's symptoms of illness or pain. The study also sought to learn more about physicians' early life experiences with health and illness and their potential to shape diagnostic thinking and treatment. Ten physician participants were interviewed using an open-ended, semistructured interview methodology. Interviews were analyzed using an alternative narrative approach described by Mishler (1986, 1991) to identify key themes within and across interviews for comparative analysis. The subjective experience and dynamic discourse between interviewer and participant were also analyzed (Mishler, 1991; Paget, 1983). Four key themes emerged: (1) the experience of certainty and uncertainty; (2) physician search for restitution; (3) the path to truth and the construction of the physician's illness narrative; and (4) the parallel anxiety between physician and parent. Findings suggested a "stages of training" model or developmental career theme associated with the ways in which physicians make meaning of persistent medically unexplained illness or pain in the child. Implications for diagnosis and treatment include the possibility that the nature of the relationship between physicians and parents-- particularly the ability to negotiate trust, intimacy, and power--may lead to a hidden and collaborative meaning making of symptoms that occurs in exclusion, of the child, Certain early life experiences of the physician may also be brought to bear in the medical encounter with parent and child. Physicians would benefit from training in neutrality and negotiation of therapeutic goals with parents of sick children, as well as training to enhance self-awareness and understanding of the ways in which alliances and conflicts with patients and parents may occur as a result of family of origin issues.
362

A topological framework for modeling belief revision

Jeftha, Lindsey Craig 12 1900 (has links)
Thesis (PhD (Mathematics))--University of Stellenbosch, 2010. / ENGLISH ABSTRACT: Classical formulations model belief revision as a deterministic process. Under certain circumstances, the process may have more than one outcome, which suggests that belief revision is non-deterministic instead. Representations exist that model belief revision in either format, and for both formats there are axiom schemes that determine whether the representation is in fact a belief revision process. Although the axiom scheme for the non-deterministic case generalises that of the deterministic case, both schemes entail that all of the beliefs held by an agent are affected by new information, which is perhaps unintuitive. Rather, one may consider that belief revision should be local, with beliefs only affected if the new information is pertinent to them. We approach the problem of belief revision from the standpoint that it is local and non-deterministic, and the purpose and contribution of this dissertation is the development of a topological framework with which to model belief revision in this manner. / AFRIKAANSE OPSOMMING: Geloofshersiening word gewoonlik as ’n deterministiese proses voorgestel. Meer as een uitkoms mag bestaan vir verskeie omstandighede, wat aandui dat die proses liewer nie-deterministies van aard is. Beide die gevalle word deur aksiomaskemas gereguleer, en die aksiomas vir die nie-deterministiese geval veralgemeen dié van die deterministiese geval. Albei aksiomaskemas stipuleer, miskien onintuïtief, dat alle gelowe van ’n agent deur die nuwe informasie geaffekteer word. ’n Beter metode is dat net daardie gelowe waarvoor die nuwe informasie toepaslik is geaffekteer word. Ons benader die probleem van geloofshersiening uit die standpunt dat dit lokaal en nie-deterministies is, en die doel en bydrae van hierdie proefskrif is dus die ontwikkeling van ’n topologiese raamwerk waarmee ons geloofshersiening op hierdie manier kan voorstel.
363

The relationship between inhibitory control and System 1 and System 2 processes in deductive and spatial reasoning.

Graham, Charlotte January 2007 (has links)
Dual Processing theory proposes that the ability to over ride associative (System 1) in favour of analytical (System 2) processed in deductive reasoning may depend on inhibitory control. The present study applies this association to a spatial reasoning task by adapting a mental rotation task to a multichoice format including System 1 (mirror) and System 2 (rotated image) responses. Fifty undergraduate volunteers from the University of Canterbury responded to a Stroop task as a measure of inhibitory control that was compared with System 1 and System 2 responding from a spatial and a deductive reasoning task. It was expected that people with weaker inhibitory potential would make more System 1 and fewer System 2 responses in both deductive and visual-spatial reasoning tasks. Contrary to expectation System 2 responding dominated for both tasks and correlations between both reasoning tasks and measures of inhibitory control were non-significant. The differing idiosyncratic demands of each task may have obscured any common variables associated with inhibitory control. This research initiated a test for the presence of System 1 and System 2 in spatial reasoning.
364

Lossless Coding of Markov Random Fields with Complex Cliques

Wu, Szu Kuan Steven 14 August 2013 (has links)
The topic of Markov Random Fields (MRFs) has been well studied in the past, and has found practical use in various image processing, and machine learning applications. Where coding is concerned, MRF specific schemes have been largely unexplored. In this thesis, an overview is given of recent developments and challenges in the lossless coding of MRFs. Specifically, we concentrate on difficulties caused by computational intractability due to the partition function of the MRF. One proposed solution to this problem is to segment the MRF with a cutset, and encode the components separately. Using this method, arithmetic coding is possible via the Belief Propagation (BP) algorithm. We consider two cases of the BP algorithm: MRFs with only simple cliques, and MRFs with complex cliques. In the latter case, we study a minimum radius condition requirement for ensuring that all cliques are accounted for during coding. This condition also simplifies the process of conditioning on observed sites. Finally, using these results, we develop a systematic procedure of clustering and choosing cutsets. / Thesis (Master, Mathematics & Statistics) -- Queen's University, 2013-08-12 14:50:00.596
365

Beliefs and the Scientific Enterprise: a Framework Model Based on Kuhn's Paradigms, Polanyi's Commitment Framework, and Radnitzky's Internal Steering Fields

Joldersma, Clarence W. January 1982 (has links)
A signed LAC Non-Exclusive License form from this author is pending. / In this thesis I attempt to develop an alternative to the logical positivist's image of science, which attempts to exclude beliefs from scientific investigations. First I set the problem up by describing what the positivists mean by belief and how they attempt to exclude belief through the use of the scientific method. I begin to develop an alternative by examining the views of three philosophers of science: Thomas S. Kuhn, Michael Polanyi, and Gerard Radnitzky. Each of them provides an alternative to the positivistic conception of science by suggesting that scientific research is surrounded by a framework of tacit beliefs. I present each view in the following way. First I describe the background and context for the framework hypothesis; then I explain the framework itself, including discussions on the nature of the framework, how it is acquired, its role in visible scientific activity, and how switches from one framework to another occur; finally I assess each person's insights, including each's relevance for my thesis. The examination of these views sets the stage for my last chapter. Here I briefly compare the three thinkers, noting similarities and differences. Then I highlight each thinker's unique insights. Finally, I present a brief description of what I believe is a viable alternative to the positivistic image of science, based on the work of the three philosophers.
366

A cortical model of object perception based on Bayesian networks and belief propagation

Durá-Bernal, Salvador January 2011 (has links)
Evidence suggests that high-level feedback plays an important role in visual perception by shaping the response in lower cortical levels (Sillito et al. 2006, Angelucci and Bullier 2003, Bullier 2001, Harrison et al. 2007). A notable example of this is reflected by the retinotopic activation of V1 and V2 neurons in response to illusory contours, such as Kanizsa figures, which has been reported in numerous studies (Maertens et al. 2008, Seghier and Vuilleumier 2006, Halgren et al. 2003, Lee 2003, Lee and Nguyen 2001). The illusory contour activity emerges first in lateral occipital cortex (LOC), then in V2 and finally in V1, strongly suggesting that the response is driven by feedback connections. Generative models and Bayesian belief propagation have been suggested to provide a theoretical framework that can account for feedback connectivity, explain psychophysical and physiological results, and map well onto the hierarchical distributed cortical connectivity (Friston and Kiebel 2009, Dayan et al. 1995, Knill and Richards 1996, Geisler and Kersten 2002, Yuille and Kersten 2006, Deneve 2008a, George and Hawkins 2009, Lee and Mumford 2003, Rao 2006, Litvak and Ullman 2009, Steimer et al. 2009). The present study explores the role of feedback in object perception, taking as a starting point the HMAX model, a biologically inspired hierarchical model of object recognition (Riesenhuber and Poggio 1999, Serre et al. 2007b), and extending it to include feedback connectivity. A Bayesian network that captures the structure and properties of the HMAX model is developed, replacing the classical deterministic view with a probabilistic interpretation. The proposed model approximates the selectivity and invariance operations of the HMAX model using the belief propagation algorithm. Hence, the model not only achieves successful feedforward recognition invariant to position and size, but is also able to reproduce modulatory effects of higher-level feedback, such as illusory contour completion, attention and mental imagery. Overall, the model provides a biophysiologically plausible interpretation, based on state-of-theart probabilistic approaches and supported by current experimental evidence, of the interaction between top-down global feedback and bottom-up local evidence in the context of hierarchical object perception.
367

Macroalgal dynamics on Caribbean coral forereefs

Renken, Hendrik January 2008 (has links)
Tropical coral reefs are among the most diverse ecosystems of the world but facing increasing threats to their health. Over the last thirty years, many Caribbean coral reefs have undergone dramatic changes and experienced large losses in coral cover, due to direct and indirect anthropogenic disturbances. The results of which are reefs with low rugosity, changed trophic dynamics and low fish diversity. In recent times reefs have failed to recover from disturbances due to an increase in frequency and severity of disturbances and stresses. In the Caribbean on many coral reefs this has resulted in a shift towards macroalgal dominance by species of the phylum Phaeophyta. The processes and factors affecting the standing crop of macroalgae are many and complex. Two main hypotheses are identified in the literature as being the driving forces of algal dynamics: nutrient dynamics (availability, supply and uptake) and herbivory. However, many studies have been found to be inconclusive because of the complexity of the coral reef ecosystem, which makes it difficult if not impossible to control for all factors and processes influencing the standing crop of macroalgae such as light, water flow and sedimentation. The inherent characteristics of macroalgae, like morphology and life history, make them behave differently. Whilst herbivore characteristics, like size of mouth parts, feeding modes and preferences, will influence the amount of algal biomass removed. The spatial context (i.e. coral fore reef vs. back reef) will influence the effects of both bottom-up and top-down controls. Besides these inter-habitat differences, macroalgae within similar habitats but differing geographical locations may respond differently, for example, a forereef exposed to the open ocean or a forereef located in a sheltered bay. This thesis attempts to provide insight into the dynamics of two dominant brown macroalgae on Caribbean coral reefs, Dictyota spp. and Lobophora variegata. This aim was addressed by developing a model for the macroalga species Dictyota to model the various processes and factors on a coral forereef affecting percentage cover. Further, the patch dynamics of both Lobophora variegata and Dictyota were investigated to gain an insight into their dynamics under varying environmental conditions: the windward and leeward sides of an atoll. Finally, herbivory is identified as one of the key process affecting macroalgal cover. I investigated this process by deploying cages on both the windward and leeward side of the atoll to investigate the effects of grazing pressure under varying environmental conditions. A Bayesian Belief Network model was developed for Dictyota spp. to model the bottom-up and top-down processes on a coral forereef determining the percentage cover. The model was quantified using relationships identified in the scientific literature and from field data collected over a nine moth period in Belize. This is the first BBN model developed for brown macroalgae. The fully parameterized model identified areas of limited knowledge and because of its probabilistic nature it can explicitly communicate the uncertainties associated with the processes and interactions on standing crop. As such the model may be used as a framework for scientific research or monitoring programmes and it is expected that the model performance to predict macroalgal percentage cover will improve once new information becomes available. Size-based transition matrices were developed for both Dictyota spp. and Lobophora variegata to investigate the patch dynamics under varying environmental conditions: the windward and leeward sides of an atoll. The matrices reveal that standard measures of algal percent cover might provide a misleading insight into the underlying dynamics of the species. Modelling the patch dynamics with matrices provided insight into the temporal behaviour of macroalgae. This is an important process to understand because patch dynamics are determining competitive interactions with other coral reef benthic organisms. The outcome of competitive interactions will differ with macroalgal species. This study indicate that Dictyota spp. responded strongly to differing environmental conditions in that it has reduced growth rates and lower percent cover on the leeward side of the atoll, whilst Lobophora variegata showed far less sensitivity to environmental conditions. The patch dynamics of Dictyota spp. also showed a higher temporal variation than Lobophora variegata but only on the exposed forereef. A caging experiment was set up to investigate the response of both macroalgal species to different grazing pressure scenarios, under varying environmental conditions. Dictyota spp. had a significant response to environmental conditions in that a higher percentage cover was found on the exposed side of the atoll, whilst for Lobophora variegata the response was far less obvious. The less clear response of Lobophora variegata was very likely caused by competition of Dictyota with Lobophora due to the very high cover Dictyota obtained in the cages where all herbivores were excluded. The low grazing pressure treatments also showed an increase in cover of Dictyota, whilst for Lobophora, only a reduction in the rate of increase could be observed. The results indicate that on the leeward side of the atoll, fish grazing alone seems sufficient to control the standing crop of Dictyota and Lobophora variegata. Retrospective analysis of the experimental design showed that the limited size of the experimental set up could have confounded the results for Lobophora as well. In future experiments it is recommended to increase number replicates. Management of coral reef habitats is frequently constrained by a lack of funds and resources. The BBN Model once fully parameterized can provide a useful tool for coral reef management, because the model allows exploration of different reef scenario’s, which in turn can aid in prioritizing management strategies. Furthermore, the thesis provided an insight into the complexities of macroalgal dynamics. The responses of macroalgae to physiological factors and ecological processes are species specific and dependent on the location, and caution against generalizing on what controls the standing crop of macroalgae. Therefore it is argued that future investigations into algal ecology should clearly define the species, habitat and location. This can help to make informed management decisions.
368

Breast self-examination : the effects of autobiographical accounts and a multimedia support program on women's knowledge, beliefs and behaviour

Smith, Nicola January 2012 (has links)
Each year more than 44,000 women are diagnosed with breast cancer and more than 12,000 of these die from the disease. These mortality rates are relatively high compared to the rest of Europe (Berrino et al., 2007; Mayor, 2003), which in part is due to the advanced stage of the disease at first presentation (McCready et al., 2005; Sant et al., 2003). Regular breast self-examination (BSE) can facilitate early detection (Cancer Research UK, 2008), yet it is not widespread. Identifying the motivational and contextual factors is likely to lead to the development of effective interventions as part of being ‘breast-aware’. This is particularly important given that mammography screening may not be effective (Crossing & Mansezewicz, 2003) or recommended for younger women (Cancer Research UK, 2008) and that BSE may be beneficial in offering women the opportunity to create a positive relationship with their body. This study considered the utility of a proposed Extended Health Belief Model (E-HBM) as a framework for understanding women’s knowledge, beliefs and behaviour. It sought to develop a new way to provide guidance and to encourage BSE by investigating the effect of autobiographical accounts of breast-cancer patients and a multimedia BSE support programme comparing video-enhanced or static guided instructions. The study adopted a 2x2 mixed methods design and 60 white British women aged between 19 and 67 participated. Analysis of Covariance revealed an interaction effect of autobiographical accounts and BSE support on BSE frequency and proficiency and regression analyses examined the utility of the E-HBM, with confidence being the main predictor. Moreover, thematic analysis elicited five themes; Previous Experience, BSE Irregularity, Perceived Susceptibility, Coping Style and The Usability of the 5 Step Model of BSE. The study concludes that the 5-step technique encourages BSE through creating a more pleasant experience, as women form an improved relationship with their breasts. Both the video-enhanced and static BSE supports are effective in terms of encouraging BSE and the effect of autobiographical accounts appears to be dependent on the type support. The practical implications and direction for future BSE interventions are discussed.
369

Essays on Artefactual and Virtual Field Experiments in Choice Under Uncertainty

Tsang, Ming 01 December 2016 (has links)
In the area of transportation policy, congestion pricing has been used to alleviate traffic congestion in metropolitan areas. The focus of Chapter 1 is to examine drivers’ perceived risk of traffic delay as one determinant of reactions to congestion pricing. The experiment reported in this essay recruits commuters from the Atlanta and Orlando metropolitan areas to participate in a naturalistic experiment where they are asked to make repeated route decisions in a driving simulator. Chapter 1 examines belief formation and adjustments under an endogenous information environment where information about a route can be obtained only conditional on taking the route. If the subjects arrive to the destination late, i.e. beyond an assigned time threshold, they are faced with a discrete (flat) penalty. In contrast, Chapter 2 examines subjective beliefs in a setting where the penalty for a late arrival is continuous, such that a longer delay incurs additional penalty on the driver. The primary research question is: does belief formation differ when the late penalty is induced as a continuous amount compared to when it is induced as a discrete amount? In particular, will we observe a difference in learning across the range of congestion probabilities under different penalty settings? In the continuous penalty setting, we do not observe a difference in learning across the range of congestion probabilities. In contrast, in the discrete penalty setting we observe significant belief adjustments in the lowest congestion risk scenario. In Chapter 3 the “source method” is used to examine how uncertainty aversion differs across events that have the same underlying objective probabilities but are presented under varying degrees of uncertainty. Subjects are presented with three lottery tasks that rank in order of increasing uncertainty. Given the choices observed in each task a source function is estimated jointly with risk attitudes under different probability weighting specifications of the source function. Results from the Prelec probability weighting suggest that, as the degree of uncertainty increases, subjects display increased pessimism; in contrast, the Tversky-Kahneman (1992) and the Power probability weightings detect no such difference. Thus, the conclusion regarding uncertainty aversion are contingent on which probability weighting specification is assumed for the source function.
370

The Healing Power of Music and Chants amongst The Ahl-E Haqq People

Vatanpour, Azadeh 01 April 2017 (has links)
This thesis examines current practices of music and prayers in the context of Jam ritual among the Ahl-e Haqq, a vernacular religion group in Iranian Kurdistan. I examine the construction and sacralization of the sacred instrument of the Ahl-e Haqq, tanbūr. I also explore the sacred prayer, kalām, and the association of prayer and music. Through the ethnographic method, participant observations, and interviewing religious figures and master musicians during the fieldwork in Sahneh, Iran, I investigate the relation of the Ahl-e Haqq prayers and music, and their effect on healing during their sacred ritual performance. Drawing primarily on scholarship from David Hufford and Bonnie Blair O’Connor, I theorize to show the distinction between healing and cure. Also using Leonard Primiano’s concept of vernacular religion, my aim is to show how the Ahl-e Haqq define their vernacular health belief system. This thesis examines the effect of music and prayers on healing in particular contexts and how it influences the daily wellbeing.

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