Dissertations / Theses on the topic 'Shafran'

The pivotal role of inflated responsibility beliefs in the maintenance and treatment of obsessive-compulsive disorder (OCD) has been clearly demonstrated (Rachman, 1993; Salkovskis, 1998; Shafran, 1997; van Oppen & Arntz, 1994). Yet little is known about the origins of these beliefs, their contribution to a sense of inflated responsibility or the symptoms of OCD, or the contribution of personality to inflated responsibility and to OCD, The aims of this thesis were to investigate a model of the inter-relationships among the personality dimensions of neuroticism and psychoticism, inflated responsibility and OCD, and the origins of inflated responsibility to inflated responsibility and to OCD. In order to achieve these aims, a scale was developed to assess the origins of inflated responsibility based upon the five pathways proposed by Salkovskis, Shafran, Rachman, and Freeston (1999) and the additional domains of guilt, vigilance and thought-action fusion (Shafran, Thordarson, & Rachman, 1996; Shafran, Watkins & Charman, 1996; Tallis, 1994). Eighty-four participants with OCD (age M = 43.36) and 74 control participants (age M =37.14) volunteered to participate in the two studies of this thesis. The aim of Study 1 was to develop and validate a measure of the Origins of Inflated Responsibility (OIR). The results of the first study yielded a 25-ttem scale, the Origins of Inflated Responsibility Questionnaire (OIRQ) with five independent factors: responsibility, strictness, protection from responsibility, critical incidents, and peer blame which demonstrated both internal reliability and temporal stability over a 2-week period. In Study 2, participants also completed the Responsibility Attitudes Scale (Salkovskis, Wroe, Gledhill, Morrison, Forrester, Richards, ct al. (2000) (a measure of inflated responsibility), the Padua Inventory (Sanavio, 1988) (to measure of the symptoms of OCD)y and the Eysenck Personality Inventory-Revised (Eysenck & Eysenck, 1991). Multivariatc Analysis of Variance revealed that the OCD group scored higher on all variables than the control group except for strictness where the groups were not different, and psychoticism where the OCD group scored lower. A series of Multiple Regression analyses revealed that both group and the OIR contributed to inflated responsibility (R2 = .56). When all variables, OIR, inflated responsibility and neuroticism were entered as predictors of OCD, 60% of the variance in OCD was explained however, 49% of the variance was shared by the independent variables suggesting the presence of some underlying construct. Structural Equation Modelling, where all the constructs in the model were examined simultaneously, revealed that neuroticism contributed to the OIR, inflated responsibility and OCD. The OIR were also significant predictors of inflated responsibility and indirectly through inflated responsibility predictive of OCD. The OIR also directly predicted OCD and when the total effects are considered, their contribution was greater than the total effect for inflated responsibility alone. The results of these studies provide good support for the origins of inflated responsibility proposed by Salkovskis et al. (1999), as measured by the OIRQ developed for use in the current thesis. The results also support the contribution of inflated responsibility and neuroticism, as well as the OIR, to OCD, The large amount of variance shared by the OIR, inflated responsibility and neuroticism suggest that there might be some underlying construct, perhaps of a biopsychosocial nature, that requires further investigation for its role in the onset and maintenance of OCD. The clinical relevance of these findings is discussed in terms of early prevention strategies and interventions.

Neste trabalho estudamos uma formulação variacional para a equação de Grad-Shafranov em um conjunto aberto e limitado n c IR. n . Primeiro estabelecemos a relação entre a formulação variacional e a equação original. A seguir, conforme o trabalho de P. Laurence e W. Stredulinsky, provamos que o funcional desta formulação possui um mínimo (supostamente a solução do problema original) e que este possui algumas propriedades de regularidade. Estudamos então o problema quando o domínio n for convexo. Para este caso, apresentamos uma espécie de discretização devido aos mesmos autores. Estabelecemos ainda propriedades geométricas importantes para a solução do problema discretizado.
In this work we study a variational formulation to the Grad-Shafranov equation in an open and bounded set n C 1R n. First we establish a relationship between the variational formulation anel the original equation. Then, according to P. Laurence and \V. Stredulinsky we prove that the functional of this formulation attains a. minimum (supposedly the solution of the original problem) a.nd this minimum has some characteristics of regularity. For the case of n convex, we introduce a kind of discretisation due to the above mentioned authors. We finally establish some important geometric properties of the solution of the discretised problem.

The main objective of this thesis is to model the magneticstructure of interplanetary coronal mass ejections (ICME) measuredin-situ from the WIND spacecraft positioned at L1. The modeling isdone by a magnetohydrodynamic reconstruction technique based onthe GS equation with a toroidal geometry. The purpose has been toextend the application of the reconstruction program to real dataand to test its performance when different input parameters arechanged. Two events are presented; 16-17 May 2012 and 15-16 May2005 ICMEs have been successfully reconstructed with this model. The main achievements of the study are that a) the code now worksfor real data b) the important parameters that can be changed fordifferent reconstructions in the code are the number of iterationsused to find the optimal Z-axis, the plasma pressure and the orderof the polynomial fitting of the flux functional, c) if all crosssection reconstructions for different variations of theseparameters strongly resembles each other then this is anindication that the model approximation is good and that the fluxrope exists. The results have been compared and verified withpreviously published studies of these events. Using a toroidal geometry for the GS reconstruction method weobtain very similar results to the one obtained with differentreconstruction techniques.This implies that at L1, the ICMEs haveexpanded so much that a cylindrical geometry is sufficient todescribe the flux rope geometry. The toroidal Grad-Shafranovreconstruction technique is best suited for circular, or slightlyelongated, flux rope cross section profiles but have been provento work for one complex ejecta consisting of two merged fluxropes. The toroidal model might become an important asset in thefuture when data from spacecraft closer to the Sun, such as ParkerSolar Probe and Solar Orbiter, is public. When the major radius ofthe flux rope is smaller the choice of geometry will most likelyhave a larger role than for measurements at L1 and so, thetoroidal Grad-Shafranov reconstruction technique will probably bethe better alternative of the models that exists today.

A determinação precisa e rápida das configurações de equilíbrio Magnetohidrodinâmico (MHD) em tokamaks é de fundamental importância para o confinamento magnético do plasma. Através do conhecimento dos parâmetros que caracterizam este equilíbrio MHD é possível controlar o plasma durante a sua formação por processos de realimentação. Uma análise mais detalhada destes parâmetros é necessária, também, entre um disparo e outro, para a estruturação do experimento. Neste trabalho é investigada a reconstrução das configurações de equilíbrio MHD no tokamak TCA/BR a partir de medidas magnéticas externas, utilizando um método que permite uma rápida determinação dos parâmetros principais da descarga. A tese divide-se em duas partes. Na primeira, é apresentada a construção de um código de equilíbrio que resolve a equação de Grad-Shafranov para a configuração geométrica que caracteriza o tokamak TCA/BR. Na segunda, é descrito o processo de reconstrução do equilíbrio MHD através de medidas de campos e fluxos magnéticos externos ao plasma no TCA/BR, e utilizando o método de Função de Parametrização FP. Este método baseia-se no tratamento estatístico de um banco de dados simulados de configurações de equilíbrio, com o objetivo de obter uma expressão simples relacionando os parâmetros que caracterizam o equilíbrio e as medidas realizadas. Os resultados obtidos através da FP são comparados com os obtidos através de outros métodos convencionais.
The accurate and rapid determination of the Magnetohydrodynamic (MHD) equilibrium configuration in tokamaks is a fundamental subject for the magnetic confinement of the plasma. With the knowledge of characteristic plasma MHD equilibrium parameters it is possible to control the plasma position during its formation using feed-back techniques. It is also necessary an on-line analysis between successive discharges to program external parameters for the subsequent discharges. In this work it is investigated the MHD equilibrium configuration reconstruction of the TCA/BR tokamak from external magnetic measurements, using a method that is able to determine fastly the main parameters of discharge. The thesis has two parts. Firstly it is presented the development of an equilibrium co de that solves de Grad-Shafranov equation for the TCA/BR tokamak geometry. Secondly it is presented the MHD equilibrium reconstruction process from external magnetic field and flux measurements using the Function Parametrization FP method. This method is based on the statistical analysis of a database of simulated equilibrium configurations, with the goal of obtaining a simple relationship between the parameters that characterize the equilibrium and the measurements. The results from FP are compared with conventional methods.

Ce travail de recherche présente une méthode originale de résolution de l'équation de Grad-Shafranov en MHD idéale pour un équilibre axisymétrique avec frontière libre. Le problème est résolu dans un espace orthogonal des flux où l'équation de Grad-Shafranov se réduit à un Laplacien. Un principe variationnel est ensuite utilisé afin d'obtenir la solution. Le maillage est un ensemble de lignes de flux qui sont déplacées jusqu'à ce que l'équilibre soit atteint. La frontière libre est déformée suivant un algorithme de minimisation d'erreur du type Newton-Raphson jusqu'à ce que le flux soit constant le long de la frontière. Le mariage de ces deux méthodes permet de calculer précisément et rapidement l'équilibre pour des géométries et des pressions de fluide variées
This work presents a unique method to solve the Grad-Shafranov equation for an ideal axisymmetric MHD equilibrium with free boundary. This problem is solved in an orthogonal flux space reducing the Grad-Shafranov equation to a Laplacian which allows to use a variationnal principle to obtain the solution. The mesh is a set of flux lines which are deformed until they all rest in equilibrium. The free boundary is treated using an error minimization based on Newton-Raphson algorithm which moves the boundary until the flux is constant along it. The coupling of these two medhods gives really quick and precise equilibriums for all sorts of fluid shapes and pressures

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Cette thèse participe au développement de méthodes numériques avancées pour simuler les instabilités du plasma pour la fusion par confinement magnétique dans les tokamaks. Ces écoulements sont décrits dans un cadre général par des modèles fluides de type magnetohydrodynamique(MHD) et peuvent être considérés comme incompressibles dans certaines approximations connues sous le nom de modèles MHD réduits. Dans ce travail, la contrainte d’incompressibilité est traitée par l’introduction de fonctions de courant. Une conséquence de cette formulation est l’apparition de termes différentiels d’ordre 4 dans les équations. L’utilisation de fonctions C 1 est alors nécessaire pour appliquer la méthode des éléments finis de Galerkin conforme. Nous avons utilisé la méthode des éléments finis dite de Clough Tocher(CT) réduite sur des triangulations générales. La méthode a été validée sur des problèmes simples, puis étendue à des problèmes pertinents pour l’étude des plasmas de fusion. Tout d’abord, l’équilibre des plasmas décrit par l’équation de Grad-Shafranov a été abordé. Ensuite, nous avons étudié des modèles incompressibles dans une formulation fonction de courant pure. Premièrement, nous avons introduit une discrétisation des équations incompressibles de Navier-Stokes qui constituent un sous-modèle des équations de la MHD incompressible. Nous avons montré la stabilité en énergie de la méthode et démontré ses performances sur certains cas tests standards. Nous avons ensuite étendu ce schéma numérique aux équations de la MHD incompressible. Nous avons également démontré la stabilité en énergie de l’approche numérique et appliqué le schéma numérique à la simulation d’un problème d’instabilité du plasma connu sous le nom de "instabilité du tilt".Au vu des résultats obtenus, la méthode CT s’est révélée adaptée à la simulation des instabilités du plasma décrites par les modèles MHD. En raison de sa capacité à représenter des géométries complexes, elle se compare favorablement aux autres méthodes numériques en termes de précision, de temps CPU, de coût mémoire et de la flexibilité
This thesis participates in the development of advanced numerical methods to simulate plasma instabilities for fusion by magnetic confinement in tokamaks. These flows are described in a general framework by magnetohydrodynamic(MHD) fluid models and can be considered incompressible in some approximations known as reduced MHD models. In this work, the incompressibility constraint is dealt with by the introduction of stream functions. A consequence of this formulation is the appearence of differential terms of order 4 in the equations. The use of C 1 functions is then required to apply the conforming Galerkin finite element method. We have used the the so-called reduced Clough-Tocher(CT) finite element method on general triangulations. The method has been validated on simple problems and then extented to problems relevant for the study of fusion plasmas. First, plasma equilibrium described by the Grad-Shafranov equation, has been investigated. Then we have studied incompressible models in a pure streamfunction formulation. First, we introduced a discretization of the incompressible Navier-Stokes equations which constitute a sub-model of the incompressible MHD equations. We have shown the stability in energy of the method and demontrated its performance on some standard test cases. We have then extended this numerical scheme to the incompressible MHD equations. We have also proved the stability in energy of the numerical approach and applied the numerical scheme to the simulation of the well known "tilt instability". In view of the results obtained, the CT method appears to be suitable for the simulation of plasma instabilities described by MHD models. Due to its capability to represent complex geometry, it compares favorably to other numerical methods in term of accuracy, CPU time, memory cost and versatility. jfavorably to other numerical methods in term of accuracy, CPU time, memory cost and versatility

This thesis uses affect theory and studies of emotion to analyse literary representations of the everyday in fictional and non-fictional writing about Muslim migrant women in the UK from 1906 to 2012. Postcolonial literary studies tend to value exceptional events over mundane life, which causes possible issues of exoticism and a danger of homogenising distinct experiences. This thesis offers a theorisation of migration that foregrounds everyday experience through an engagement with theories of objects, bodies and space, as well as emotional experiences that are specific to migrant subjectivity. It analyses two groups of texts: early twentieth century travel writing by Atiya Fyzee, Shahbano Begum Maimoona Sultan and Zeyneb Hanoum, and contemporary literary texts by Yeshim Ternar, Farhana Sheikh, Monica Ali, Leila Aboulela, Elif Shafak and Fadia Faqir. The thesis is structured thematically into three sections, each section containing two chapters, one about travel writing and another about contemporary texts. In the first section, in order to examine how the texts negotiate foreignness in daily life, I consider hospitality theory, which describes how social power relations are based on roles of host and guest. In the second section, I argue that melancholia is an emotional experience endemic to migrancy. The texts demonstrate how this emotion is manifest communally as well as individually, which also shows the political potential of emotion. In the third section, I investigate how emotional processes of migration are described spatially in the texts. The findings of this research show that emotional knowledge is a major concern for migrant writers as a way of engaging with and critiquing the social and political climates of each text. This is produced through narrations about feeling in general and specific emotions, such as irritation or anxiety. Emotional experience is illustrated in conjunction with identities that are both fluid and intersectional, where gender and class converge with ethnicity and religion. The texts also show specifically affective styles of writing that concentrate on focalising women's intimate experiences through, for example, diary entries, bildungsroman or psychological realism. While the differing contexts reflect the particularities of each experience, there are sufficient similarities of narrative content and style to suggest that affective experience is a major concern for this body of literature. Overall, this thesis demonstrates the productive uses of affect theory as a critical stance for analysing postcolonial literature.

碩士
國立中央大學
數學研究所
97
In this thesis, we consider a new type of Grad-Shafranov equation : $$displaystyle Delta u=Big(1+frac{cu}{kappa}Big)^{-kappa+frac{1}{2}} $$ arising from the plasma physics (see Ref. cite{HF1} and cite{HF2} by L.-N. Hau and W.-Z. Fu). Using the method of regular perturbation, we investigate the limiting behavior of positive solutions (for 1D case) with respect to the parameter Kappa $kappa$ (as $kappa o infty$). In addition, the global existence, uniqueness and asymptotic behavior of positive radial solutions will be proved as well.

博士
國立中央大學
太空科學研究所
95
Grad-Shafranov (GS) reconstruction technique is a data analysis tool for reconstruction of two-dimensional (2D) coherent field structures from data taken by single satellite traversing a current layer by solving the GS equation as a spatial initial value problem. For magnetohydrostatic approximation, the GS reconstruction technique has been developed by Hau and Sonnerup [1999] and successfully applied to the Earth’s magnetopause, to the magnetic cloud in the solar wind, and to the flux rope by various authors. In previous studies based on the analysis of AMPTE/IRM and Cluster data, the magnetopause current layers of tangential-discontinuity type are found to be imbedded with a string of magnetic islands moving down the magnetotail. In this thesis, we first present a rare event of triple magnetopause crossings encountered by AMPTE/IRM using the similar magnetohydrostatic GS construction method that shows similar features of magnetic islands embedded within the overall tangential discontinuity-like current layer. Detailed analyses of the magnetopause normal orientation, the deHoffmann-Teller (HT) velocity, and the invariant axis indicate that these are likely to be part of the same magnetopause structures moving inward and outward seen by the same spacecraft. The thesis also presents the first new results from a recently developed version of GS reconstruction in the presence of field-aligned flow based on the formulation of Sonnerup et al. [2006] that can be applied to rotational discontinuity-like magnetopause current layer structures. A new GS solver that incorporates the field-aligned flow is benchmarked with an exact analytical solution to demonstrate the accuracy of the new GS reconstruction scheme. It is then applied to the magnetopause crossings by the AMPTE/IRM on September 15, 1984, and by the Cluster 1 (C1) and the Cluster 3 (C3) on July 5, 2001. In the AMPTE/IRM event, the reconstructed magnetic field map shows that the magnetopause current layer becomes thinner than that recovered from the magnetohydrostatic reconstruction, an effect due to the presence of field-aligned flow [Hau, 1996]. For the Cluster event, the agreement between map-predicted and measured values of the field-line invariants along the trajectory of the spacecraft not used in generating the map is less than perfect but most of the differences are accounted by the time evolutionary effect due to developing reconnection at a site close to the spacecraft. An important new feature is that the field-aligned flow, as seen in the HT frame, is supersonic in the magnetopause region and is qualitatively and quantitatively as expected for supersonic flow in a duct (a flux tube). We provide an estimate of 0.47 mV/m for the reconnection electric field.