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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.
231

Investigation of Lateral-Directional Coupling in the Longitudinal Responses of a Transfer Function Simulation Model

Leonard, John 17 December 2003 (has links)
The linear variable stability Transfer Function Simulation Model (TFSM), inspired by the United States Air Force's NF-16D Variable stability In-flight Simulator Test Aircraft (VISTA) and created by Henrik Pettersson, can simulate any desired aircraft. The TFSM represents a non-linear aircraft model with its stability parameters - a collection of gain constants, time constants, damping ratios, and natural frequencies. Stability parameters for aircraft generally fall into two uncoupled modes: longitudinal and lateral-directional. Unfortunately, flight tests using the TFSM exhibited undesired lateral-directional coupling in the longitudinal responses. An S-turn maneuver, formation flight test, and an uncontrolled simulation with an initial bank angle of 60 degrees were the foundation for the investigation to pinpoint the TFSM's errors. The flight tests and subsequent analysis showed that although this model is highly versatile, it has three fundamental problems. First, the original creation of the TFSM incorrectly assumed that the time rate of change for the pitch angle (in the local-horizontal reference frame) is equal to the body-axis pitch-rate for all flight conditions. Second, the TFSM's dynamics do not contain gravity terms. Third, the TFSM cannot generate the angular rates needed in a turn. Integrating the aircraft's pitch, roll, and yaw angles with the equations of motion for aircraft fixed the first problem. Unfortunately, resolving this issue only intensified the second two problems. The results from this thesis show that the last two problems are part of the TFSM and cannot be fixed explicitly. / Master of Science
232

Therapeutic Targeting of the Proinflammatory IL-6-JAK/STAT Signalling Pathways Responsible for Vascular Restenosis in Type 2 Diabetes Mellitus.

Moshapa, Flora Tshepo, Riches-Suman, Kirsten, Palmer, T.M. 31 March 2021 (has links)
Yes / Type 2 diabetes mellitus (T2DM) is increasing worldwide, and it is associated with increased risk of coronary artery disease (CAD). For T2DM patients, the main surgical intervention for CAD is autologous saphenous vein grafting. However, T2DM patients have increased risk of saphenous vein graft failure (SVGF). While the mechanisms underlying increased risk of vascular disease in T2DM are not fully understood, hyperglycaemia, insulin resistance, and hyperinsulinaemia have been shown to contribute to microvascular damage, whereas clinical trials have reported limited effects of intensive glycaemic control in the management of macrovascular complications. This suggests that factors other than glucose exposure may be responsible for the macrovascular complications observed in T2DM. SVGF is characterised by neointimal hyperplasia (NIH) arising from endothelial cell (EC) dysfunction and uncontrolled migration and proliferation of vascular smooth muscle cells (SMCs). This is driven in part by proinflammatory cytokines released from the activated ECs and SMCs, particularly interleukin 6 (IL-6). IL-6 stimulation of the Janus kinase (JAK)/signal transducer and activator of transcription 3 (STAT) pathway is a key mechanism through which EC inflammation, SMC migration, and proliferation are controlled and whose activation might therefore be enhanced in patients with T2DM. In this review, we investigate how proinflammatory cytokines, particularly IL-6, contribute to vascular damage resulting in SVGF and how suppression of proinflammatory cytokine responses via targeting the JAK/STAT pathway could be exploited as a potential therapeutic strategy. These include the targeting of suppressor of cytokine signalling (SOCS3), which appears to play a key role in suppressing unwanted vascular inflammation, SMC migration, and proliferation. / FTM is supported by a University of Botswana PhD scholarship.
233

Rapid Facial Reactions to Emotionally Relevant Stimuli

Thunberg, Monika January 2007 (has links)
<p>The present thesis investigated the relationship between rapid facial muscle reactions and emotionally relevant stimuli. In Study I, it was demonstrated that angry faces elicit increased <i>Corrugator supercilii</i> activity, whereas happy faces elicit increased <i>Zygomaticus major</i> activity, as early as within the first second after stimulus onset. In Study II, during the first second of exposure, pictures of snakes elicited more corrugator activity than pictures of flowers. However, this effect was apparent only for female participants. Study III showed that participants high as opposed to low in fear of snakes respond with increased corrugator activity, as well as increased autonomic activity, when exposed to pictures of snakes. In Study IV, participants high as opposed to low in speech anxiety responded with a larger difference in corrugator responding between angry and happy faces, and also with a larger difference in zygomatic responding between happy and angry faces, indicating that people high in speech anxiety have an exaggerated facial responsiveness to social stimuli. In summary, the present results show that the facial EMG technique is sensitive to detecting rapid emotional reactions to different emotionally relevant stimuli (human faces and snakes). Additionally, they demonstrate the existence of differences in rapid facial reactions among groups for which the emotional relevance of the stimuli can be considered to differ.</p>
234

Rapid Facial Reactions to Emotionally Relevant Stimuli

Thunberg, Monika January 2007 (has links)
The present thesis investigated the relationship between rapid facial muscle reactions and emotionally relevant stimuli. In Study I, it was demonstrated that angry faces elicit increased Corrugator supercilii activity, whereas happy faces elicit increased Zygomaticus major activity, as early as within the first second after stimulus onset. In Study II, during the first second of exposure, pictures of snakes elicited more corrugator activity than pictures of flowers. However, this effect was apparent only for female participants. Study III showed that participants high as opposed to low in fear of snakes respond with increased corrugator activity, as well as increased autonomic activity, when exposed to pictures of snakes. In Study IV, participants high as opposed to low in speech anxiety responded with a larger difference in corrugator responding between angry and happy faces, and also with a larger difference in zygomatic responding between happy and angry faces, indicating that people high in speech anxiety have an exaggerated facial responsiveness to social stimuli. In summary, the present results show that the facial EMG technique is sensitive to detecting rapid emotional reactions to different emotionally relevant stimuli (human faces and snakes). Additionally, they demonstrate the existence of differences in rapid facial reactions among groups for which the emotional relevance of the stimuli can be considered to differ.
235

Feedback Enhancement of Immune Responses by IgE, IgM, and IgG3 Antibodies

Ding, Zhoujie January 2015 (has links)
Antibodies can enhance or suppress the immune responses against their specific antigens. This phenomenon is known as antibody-mediated feedback regulation. We have studied the mechanisms underlying IgE-, IgM-, and IgG3-mediated enhancement of immune responses in mouse models using intravenous immunization. We attempted to answer the following questions: 1) Which cell type presents IgE-complexed antigens to CD4+ T cells? 2) Is complement activation required for specific IgM to enhance antibody responses? 3) Does IgM enhance CD4+ T-cell responses? 4) How are IgG3-antigen complexes transported into B-cell follicles? We found that CD23+ B cells transporting IgE-antigen complexes into B-cell follicles were not required to prime the antigen-specific CD4+ T cells in vivo, whereas CD11c+ cells were indispensable. After examining the three most common subpopulations of CD11c+ cells in the spleen, we determined that it was CD8α- conventional dendritic cells migrating into the T-cell zone following immunization that presented IgE-complexed antigens to CD4+ T cells. Next, we showed that specific IgM from Cµ13 mice, which is unable to activate complement, failed to enhance either antibody or germinal center responses whereas wild-type IgM enhanced both responses. Therefore, specific IgM must activate complement to enhance humoral responses. In addition, wild-type IgM did not up-regulate CD4+ T-cell responses. Finally, we showed that IgG3-antigen complexes were transported by marginal zone B cells into B-cell follicles via binding to complement receptors 1 and 2 (CR1/2) on those cells. The immune complexes were captured by follicular dendritic cells as early as 2 h after immunization. Germinal center responses were also enhanced by IgG3. Using bone marrow chimeric mice, we found that CR1/2 expression was required on both marginal zone B cells and follicular dendritic cells to provide an optimal enhancement of antibody responses.
236

An Exploratory Study of Children's Multi-Sensory Responses to Symbolizing Musical Sound Through Speech Rhythm Patterns

Bennett, Peggy Dee 12 1900 (has links)
The purpose of the study was to investigate the multi-sensory responses of children to symbolizing musical sound through speech rhythm patterns. Speech rhythm patterns consist of the number of syllables and the stress/nonstress relationships of these syllables in a word or a phrase. The research problems were (1) to determine children's responses to speech rhythm patterns according to the differential sensory modes used; (2) to determine the children's responses to speech rhythm patterns by age, and (3) to compare children's responses to speech rhythm patterns by age and sensory modes.
237

Programming Generalization: A Comparison of Behavioral and Cognitive Response Transfer Operations in Assertive Training

Lefebvre, Richard Craig 05 1900 (has links)
The assertive training literature has documented the effectiveness of both behavioral and cognitive methods to increase individual's assertiveness. However, the ability for such methods to enhance the generalization of treatment effects to untrained assertive response classes and the natural environment has been poor. In addition, little notice has been paid to the durability of these changes. Although the past several years have witnessed more intensive efforts by investigators to program generalization as part of their interventions, results have continued to be disappointing. A specific generalization-enhancing treatment strategy, self-directed practice, has been utilized with much success in phobic populations. This strategy, and the theoretical orientation it reflects, has been proposed for use in assertive training. The present study sought to examine the effectiveness of this method as compared to the traditional assertive training procedures and investigate the role of self-efficacy expectations in mediating initial behavior change and its subsequent generalization.
238

Guarded and Unguarded Responses to Sentence Completion Tests Among Normal Adolescents and Juvenile Delinquents

Fazel, Mohammed K. 01 May 1967 (has links)
This study was designed to test the responses of a group of juvenile delinquests and a group of normal adolescents to a sentence completion test. The test used was a modified form of Sack's Sentence Completion test in two forms--form A, first person stems and form B, third person stems. The hypothesis to be tested were (1) people project more in the third person, (2) the normal projects more, and (3) there would be no difference in projection on neutral items. The results bear out the three hypothesis. The sex scale, however, was an exception. This may be due to the deficiency of items on this particular scale.
239

Effects of Self-Selected and Imposed Intensity of Acute Exercise on the HPA-axis Response and Psychological Well-Being in Inactive Women with High Levels of Stress

Wardwell, Kyoko Konaka 02 September 2011 (has links)
No description available.
240

Effects of hypothermically reduced plantar skin inputs on anticipatory and compensatory balance responses

Germano, Andresa M. de Castro, Schmidt, Daniel, Milani, Thomas L. 30 August 2016 (has links) (PDF)
Background Anticipatory and compensatory balance responses are used by the central nervous system (CNS) to preserve balance, hence they significantly contribute to the understanding of physiological mechanisms of postural control. It is well established that various sensory systems contribute to the regulation of balance. However, it is still unclear which role each individual sensory system (e.g. plantar mechanoreceptors) plays in balance regulation. This becomes also evident in various patient populations, for instance in diabetics with reduced plantar sensitivity. To investigate these sensory mechanisms, approaches like hypothermia to deliberately reduce plantar afferent input have been applied. But there are some limitations regarding hypothermic procedures in previous studies: Not only plantar aspects of the feet might be affected and maintaining the hypothermic effect during data collection. Therefore, the aim of the present study was to induce a permanent and controlled plantar hypothermia and to examine its effects on anticipatory and compensatory balance responses. We hypothesized deteriorations in anticipatory and compensatory balance responses as increased center of pressure excursions (COP) and electromyographic activity (EMG) in response to the hypothermic plantar procedure. 52 healthy and young subjects (23.6 ± 3.0 years) performed balance tests (unexpected perturbations). Subjects’ foot soles were exposed to three temperatures while standing upright: 25, 12 and 0 °C. COP and EMG were analyzed during two intervals of anticipatory and one interval of compensatory balance responses (intervals 0, 1 and 2, respectively). Results Similar plantar temperatures confirmed the successful implementation of the thermal platform. No significant COP and EMG differences were found for the anticipatory responses (intervals 0 and 1) under the hyperthermia procedure. Parameters in interval 2 showed generally decreased values in response to cooling. Conclusion No changes in anticipatory responses were found possibly due to sensory compensation processes of other intact afferents. Decreased compensatory responses may be interpreted as the additional balance threat, creating a more cautious behavior causing the CNS to generate a kind of over-compensatory behavior. Contrary to the expectations, there were different anticipatory and compensatory responses after reduced plantar inputs, thereby, revealing alterations in the organization of CNS inputs and outputs according to different task difficulties.

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