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Thesis (Ph.D.)--University of Central Florida, 2009. / Adviser: Charles Negy. Includes bibliographical references (p. 102-107).

The aim of this thesis was to consider the role of appraisals of intrusive thoughts in the development of Obsessive-Compulsive Disorder. A narrative literature review explored the hypothesis that 'normal' intrusive thoughts lie on a continuum with clinical obsessions. The review discussed previous research on intrusive thoughts in nonclinical samples and drew comparisons with characteristics of clinical obsessions. An internet-based empirical investigation employed a randomised controlled trial design in order to test the effectiveness of an intervention based on normalising information in reducing problematic meta-cognitive beliefs. A large sample (N = 148) of young adults (aged 18-20 years) was screened in to the study based on high levels of problematic meta-cognitive beliefs. Participants completed questionnaire measures of meta-cognitive beliefs, obsessive-compulsive symptoms, reactions to intrusive thoughts and experiential avoidance. Participants completed an interactive quiz based on normalising information (experimental condition) or pet information (control condition). Significant reductions in problematic meta-cognitive beliefs and experiential avoidance were observed in both conditions, thus no additional benefit of normalising information was indicated. The implications of these findings are discussed in the context of the potential normalising effects of symptom monitoring. Overall this thesis supports the comparison of 'normal' intrusive thoughts and obsessions and suggests that negative appraisals, such as problematic metacognitive beliefs, may not be the only defining factor in the development of Obsessive-Compulsive Disorder.

Experiments were conducted to measure the thrust generated from a commercial jet engine. This thrust estimation was done using a pneumatic horn as the sound source with two arrays of microphones directly across the exhaust stream. The two arrays were separated by an axial distance downstream. Exhaust centerline measurements were taken at varying engine conditions, specifically; 30%, 50%, 60%, 70%, 80% and 100% engine power. An acoustic thrust estimation showed good agreement with measured thrust during the test campaign. In addition, a full traverse of the acoustic rig through the exhaust stream was completed for the purpose of tomography reconstruction. This reconstruction technique was able to pick up key features of the flow field. / Master of Science / A non-intrusive acoustic approach was used to measure the thrust produced by a commercial jet engine at all engine power levels. This acoustic approach was comprised of a sound source and receiving microphones placed on either side of the jet exhaust stream, just behind the engine. The acoustic measurements were compared to measurements by a load cell on the engine and showed excellent agreement. After the concept was proven, another experiment was conducted in which the sound source and microphones were moved vertically alongside the engine exhaust stream. These line of sight measurements were used to reconstruct the velocity and temperature gradients generated by the jet engine. The reconstructions showed good agreement with the engine geometry and was able to detect key flow features.

This thesis explores the role of guilt in post-traumatic stress disorder (PTSD) and ways of coping with guilt-related thoughts in a clinical sample. The thesis is presented as three papers that include a review of the literature, an empirical research study and critical appraisal of the research process. In the first paper, the author provides a systematic review of 27 studies to determine whether an association exists between guilt and symptoms of post-traumatic stress. Guilt remains an associated feature of PTSD; however, how these two constructs might be linked is not fully understood. Therefore the current review further evaluated the evidence for four competing models conceptualising the guilt-PTSD relationship. Overall, trauma-related guilt was positively related to PTSD symptomology even when controlling for depression. Guilt cognitions reflecting self-blame, perceived responsibility and wrongdoing were frequently associated with PTSD symptoms. Few studies found guilt was no longer related to PTSD symptomology when controlling for shame. Future studies ought to control for overlapping or confounding variables and further explore factors that may mediate the guilt-PTSD relationship such as coping. The second paper provided preliminary validation of a newly developed and unique measure of coping with guilty thoughts (GLAMS) in a clinical sample. A total of 67 participants from primary care services completed the GLAMS and measures of distress, guilt, coping and thought control. Eighteen completed the GLAMS and distress measure two weeks later. Overall the GLAMS evidenced moderate to high internal consistency and acceptable to good concurrent validity. Maladaptive subscales were found to be reliable over time. Higher self-punishment was related to greater guilt and distress and more mindful coping was related to a reduction in guilt supporting construct validity. Future research is required to test the stability of the GLAMS factor structure in a larger clinical sample. The GLAMS may have clinical utility in guiding psychological intervention towards more adaptive ways of coping with guilt. It may also provide a suitable outcome measure by monitoring the frequency in which clients engage in maladaptive ways of coping. The final paper provided a critical evaluation and reflection on the research process. Particular reference was made to the research rationale, methodological and ethical issues and considerations were given for future research and clinical practice. Conclusions drawn from this thesis are limited largely by the cross-sectional nature of most of the studies reviewed in paper 1 and insufficient numbers for the empirical study, which due to methodological and service-related constraints, limited further exploration of the data. Factor analysis and subsequent validation of the GLAMS in a larger sample is required to further support inferences drawn.

Although recent research has demonstrated that intrusive memories of negative autobiographical events are an overlapping cognitive feature of depression and PTSD, there is still a general paucity of research investigating the prevalence and maintenance of these memories in depression. Accordingly, the current thesis represented a much-needed program of empirically-driven research that delineated the cognitive processes that underpin the manifestation, experience, and persistence of intrusive memories in depression. Firstly, Study 1 used descriptive and correlational methodologies to outline the content and features of these memories, and explored whether intrusion characteristics linked to intrusive memories in PTSD are also features of intrusive memories in depression. In accord with studies in PTSD samples, sensory features accounted for unique variance in the prediction of depression severity, over and above that accounted for by intrusion frequency. This commonality raised the possibility that cognitive management strategies linked to the persistence of intrusive memories in PTSD may also play a role in depression. Accordingly, Study 2 utilized a cross-sectional and prospective design to investigate whether negative appraisals and cognitive avoidance strategies, which are key to the persistence of intrusive memories in PTSD, similarly play a role in depression. The results demonstrated that assigning negative appraisals to one???s intrusive memory, and attempts to control the memory, were positively associated with intrusion-related distress, level of depression, and cognitive avoidance mechanisms. Additionally, negative appraisals and the use of cognitive mechanisms were predictive of depression concurrently, but not prospectively. Studies 3, 4, and 5 further investigated avoidant intrusion- response strategies by assessing the role of recall vantage perspective in mediating the effects of intrusion-related distress. Study 3 found that although field memories were not experienced as more distressing than observer memories, the results supported an association between an observer vantage perspective and cognitive avoidance mechanisms. As this study employed a correlational design, Study 4 addressed the question of directionality by experimentally manipulating mode of recall to ascertain whether shifting participants into a converse perspective would have differential effects on the reported experience of their intrusive memory. Results indicated that shifting participants from a field to an observer perspective resulted in decreased experiential ratings; specifically, reduced distress and vividness and increased detachment and observation. Also, as anticipated, the converse shift in perspective (from observer to field) did not lead to a corresponding increase in experiential ratings, but resulted in reduced ratings of observation. Study 5 attempted to investigate the stability of this memory orientation phenomenon by investigating mode of recall vantage perspective prospectively. Attrition of participants across the 12-month study limited analyses to the descriptive level, but illustrated that, at least for some individuals, recall vantage perspective remained stable across assessments periods. Collectively, the findings supported the notion that recall perspective has a functional role in the regulation of intrusion-related distress and represents a cognitive avoidance mechanism. Studies 6 and 7 employed experimental methodologies to investigate whether adopting an abstract/analytical mode of processing following a negative event would result in poor emotional processing, or increased distress associated with intrusive memories. Study 6 found no differences in either intrusion frequency or associated levels of distress across the processing conditions, as hypothesized. The results of Study 6 suggested that the predicted effects of ruminative self-focus on intrusion severity may be dependent upon the self-referential nature of the material being processed. Results of Study 7 indicated that inducing an analytical ruminative mode of processing resulted in participants rating their naturally occurring, self-referential intrusive memories as more negative, more distressing, and evoking a more negative emotional response compared to inducing distraction. Taken together, Studies 6 and 7 suggest the possibility that depressed individuals may get caught up in a ruminative cycle that, due to the documented effects of analytical self-focus, may exacerbate the emotional response elicited by the intrusions and perpetuate biased attentional focus towards them. Finally, Studies 8 and 9 explored suppression as a cognitive avoidance mechanism and addressed some methodological concerns regarding the measurement of this construct. Study 8 investigated the effects of repeated suppression using a method to index the frequency, duration, and associated levels of distress of an experimentally-induced intrusive memory, and assessed whether any observed effects were differentially linked to depressive symptomatology. Results supported a secondary rebound effect in those participants who were most successful at suppressing target intrusions. Study 9 was an investigation of the English version of the TCAQ (Luciano, Algarabel, Tom??s, & Mart??nez, 2005), an index of cognitive control. Study 9 evaluated the association between this measure and performance on a thought suppression task. The results indicated that low TCAQ-20 scorers experienced intrusions of a longer duration and rated these intrusions as more distressing than high TCAQ-20 scorers, supporting the validity of the measure. These findings highlight the role of suppression as a maladaptive mental control strategy and the potential for elevated intrusion-distress to perpetuate its use. Together, the findings of this program of research confirm the importance of intrusive memories in depression, and underscore the need for an empirically-supported model to account for the occurrence and maintenance of these memories.

Turbulent liquid sheets have been proposed to protect solid structures in fusion power plants by attenuating damaging radiation. For the High-Yield Lithium-Injection Fusion Energy (HYLIFE-II) inertial fusion energy (IFE) power plant concept, arrays of molten-salt sheets form a sacrificial barrier between the fusion event and the chamber first wall while permitting target injection and ignition. Thick liquid protection can help make fusion energy commercially attractive by reducing chamber size and prolonging chamber lifetime. Establishing an experimental design database for this basic building block flow will provide valuable information about various thick liquid protection schemes and allow reactor designers to establish acceptable tolerances between chamber components. Turbulent water sheets issuing downwards into ambient air were studied experimentally at Reynolds numbers of 53,000 ??0,000 and Weber numbers of 2,900 ??,000 based on average velocity and the short dimension of the nozzle exit ( and delta). Initial conditions were quantified by the streamwise (x) and transverse (z) velocity components using laser-Doppler velocimetry just upstream of the nozzle exit. Characterization of the mean free-surface position and free-surface fluctuations, or surface ripple, and estimation of the amount of mass ejected as droplets from the free surface were quantified in the near-field (within 25 and delta of the nozzle exit). Surface ripple and mean sheet geometry were determined directly from planar laser-induced fluorescence visualizations of the free surface. The droplets due to the turbulent breakup of the jet, termed here the hydrodynamic source term, were measured using a simple collection technique to within 1 and delta of the nominal free surface of the jet. The influence of various passive flow control techniques such as removing low-momentum fluid at the free surface (boundary-layer cutting) on sheet geometry, surface ripple, and turbulent breakup were also quantified. The data obtained in this research will allow designers of inertial fusion energy systems to identify the parameter ranges necessary for successful implementation of the thick liquid wall protection system.

Although recent research has demonstrated that intrusive memories of negative autobiographical events are an overlapping cognitive feature of depression and PTSD, there is still a general paucity of research investigating the prevalence and maintenance of these memories in depression. Accordingly, the current thesis represented a much-needed program of empirically-driven research that delineated the cognitive processes that underpin the manifestation, experience, and persistence of intrusive memories in depression. Firstly, Study 1 used descriptive and correlational methodologies to outline the content and features of these memories, and explored whether intrusion characteristics linked to intrusive memories in PTSD are also features of intrusive memories in depression. In accord with studies in PTSD samples, sensory features accounted for unique variance in the prediction of depression severity, over and above that accounted for by intrusion frequency. This commonality raised the possibility that cognitive management strategies linked to the persistence of intrusive memories in PTSD may also play a role in depression. Accordingly, Study 2 utilized a cross-sectional and prospective design to investigate whether negative appraisals and cognitive avoidance strategies, which are key to the persistence of intrusive memories in PTSD, similarly play a role in depression. The results demonstrated that assigning negative appraisals to one???s intrusive memory, and attempts to control the memory, were positively associated with intrusion-related distress, level of depression, and cognitive avoidance mechanisms. Additionally, negative appraisals and the use of cognitive mechanisms were predictive of depression concurrently, but not prospectively. Studies 3, 4, and 5 further investigated avoidant intrusion- response strategies by assessing the role of recall vantage perspective in mediating the effects of intrusion-related distress. Study 3 found that although field memories were not experienced as more distressing than observer memories, the results supported an association between an observer vantage perspective and cognitive avoidance mechanisms. As this study employed a correlational design, Study 4 addressed the question of directionality by experimentally manipulating mode of recall to ascertain whether shifting participants into a converse perspective would have differential effects on the reported experience of their intrusive memory. Results indicated that shifting participants from a field to an observer perspective resulted in decreased experiential ratings; specifically, reduced distress and vividness and increased detachment and observation. Also, as anticipated, the converse shift in perspective (from observer to field) did not lead to a corresponding increase in experiential ratings, but resulted in reduced ratings of observation. Study 5 attempted to investigate the stability of this memory orientation phenomenon by investigating mode of recall vantage perspective prospectively. Attrition of participants across the 12-month study limited analyses to the descriptive level, but illustrated that, at least for some individuals, recall vantage perspective remained stable across assessments periods. Collectively, the findings supported the notion that recall perspective has a functional role in the regulation of intrusion-related distress and represents a cognitive avoidance mechanism. Studies 6 and 7 employed experimental methodologies to investigate whether adopting an abstract/analytical mode of processing following a negative event would result in poor emotional processing, or increased distress associated with intrusive memories. Study 6 found no differences in either intrusion frequency or associated levels of distress across the processing conditions, as hypothesized. The results of Study 6 suggested that the predicted effects of ruminative self-focus on intrusion severity may be dependent upon the self-referential nature of the material being processed. Results of Study 7 indicated that inducing an analytical ruminative mode of processing resulted in participants rating their naturally occurring, self-referential intrusive memories as more negative, more distressing, and evoking a more negative emotional response compared to inducing distraction. Taken together, Studies 6 and 7 suggest the possibility that depressed individuals may get caught up in a ruminative cycle that, due to the documented effects of analytical self-focus, may exacerbate the emotional response elicited by the intrusions and perpetuate biased attentional focus towards them. Finally, Studies 8 and 9 explored suppression as a cognitive avoidance mechanism and addressed some methodological concerns regarding the measurement of this construct. Study 8 investigated the effects of repeated suppression using a method to index the frequency, duration, and associated levels of distress of an experimentally-induced intrusive memory, and assessed whether any observed effects were differentially linked to depressive symptomatology. Results supported a secondary rebound effect in those participants who were most successful at suppressing target intrusions. Study 9 was an investigation of the English version of the TCAQ (Luciano, Algarabel, Tom??s, & Mart??nez, 2005), an index of cognitive control. Study 9 evaluated the association between this measure and performance on a thought suppression task. The results indicated that low TCAQ-20 scorers experienced intrusions of a longer duration and rated these intrusions as more distressing than high TCAQ-20 scorers, supporting the validity of the measure. These findings highlight the role of suppression as a maladaptive mental control strategy and the potential for elevated intrusion-distress to perpetuate its use. Together, the findings of this program of research confirm the importance of intrusive memories in depression, and underscore the need for an empirically-supported model to account for the occurrence and maintenance of these memories.

Le stockage des déchets radioactifs dans des formations géologiques profondes nécessite d'excaver de la roche en grande profondeur pour accueillir les différentes installations. L'argilite du Callovo-Oxfordian a été choisie comme une potentielle formation hôte grâce à sa capacité de rétention et ses propriétés hydromécaniques. L'objectif de la thèse est d'étudier numériquement la fissuration induite lors du creusement des galeries souterraines à -490 m de profondeur. Un modèle Éléments Finis 3D (méthode E-FEM) est développé pour représenter la fissuration. Plusieurs critères sont proposés pour caractériser les fissures avec une ouverture en mode I ou un glissement en mode II. L'influence de l'anisotropie des propriétés de l'argilite et du champ de contrainte in situ sur les réseaux de fractures et la convergence des galeries est principalement étudiée. L'origine géologique de l'argilite, la complexité de sa microstructure et les grandes dimensions des galeries amènent à des incertitudes sur les propriétés hydromécaniques de ce matériau. La prise en compte des variabilités spatiales des paramètres mécaniques de la roche se fait au travers de champs aléatoires corrélés. Des Méthodes Éléments Finis probabilistes avec des formulations de Galerkin (méthodes d’intégration stochastique indirecte) sont ensuite développées avec une approche non intrusive pour propager ces incertitudes pour des systèmes linéaires et non linéaires (avec et sans fissuration). Ces méthodes sont ensuite appliquées à des problèmes d’excavation pour propager les incertitudes paramétriques associées au comportement de l'argilite. Les résultats sont comparés par rapport à ceux obtenus par des méthodes d’intégration stochastique directe (famille des méthodes dites de Monte-Carlo). / A 3D numerical modelling using the Enhanced Finite Element Method (E-FEM) is developped to address induced fracture networks around drifts after an excavation in Callovo-Oxfordian claystone (COx). A transversely isotropic behaviour is considered for the host rock and two failure criteria are proposed and implemented to characterize shear and tensile fractures: an anisotropic/isotropic Mohr Coulomb criterion with sliding (mode II) and an anisotropic principal strain criterion with mode I opening. Numerical simulations of underground excavations are presented and the results are discussed compared to in situ observations. The influence of the anisotropy of rock properties and in situ stress field on the induced fractures and the convergence of drifts are also studied. The geological origin of the COx as well as the large size of drifts lead to a large uncertainty related to hydro-mechanical properties of this material. Stochastic problems for linear and non linear systems are more and more of interest because it is an important issue to quantify uncertainties when parameters (loading, material properties) are modelled by correlated random fields. Despite a slow convergence, Monte Carlo methods are the most often used to solve these problems thanks to its easy implementation (non intrusive computation). Probabilistic Finite Element methods like Galerkin formulations which produce a coupled system are often viewed as intrusive. Here, we want to show that is possible to compute them in a non intrusive way and with the same accuracy as Monte Carlo methods which are considered as a reference. These methods are applied to take into account and to propagate parametric uncertainties related to claystone's behavior. 3D Numerical results are presented and discussed concerning the induced fracture networks around drifts and the anisotropic convergence of walls.

ITC/USA 2010 Conference Proceedings / The Forty-Sixth Annual International Telemetering Conference and Technical Exhibition / October 25-28, 2010 / Town and Country Resort & Convention Center, San Diego, California / Most helicopter programs require the acquisition of parameters from the rotating systems. Historically, these systems made use of electromechanical slip rings for the transfer of power, control, and data from within the helicopter's cabin to the rotating hardware. Slip rings are primarily used in dedicated instrumentation vehicles and are not commonly used in production platforms that may require instrumentation of the rotating systems for in-service load and fatigue monitoring. Additionally, the use of slip rings requires time and money to integrate the hardware and equipment into the aircraft in order to perform rotor data acquisition. The time needed to perform modifications to transmissions and drive trains plays a big factor in the increased costs of aircraft development. Less intrusive installations would minimize the need for mechanical changes and would improve the time needed to install the instrumentation. This paper describes a wireless system approach to perform the test without the slip ring, and provides performance data that validates this new method of instrumenting unobtrusively to save time and money without sacrificing data integrity.