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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.
41

Die teoretiese en empiriese verwantskappe tussen besluitneming, temperament en samehangendheidsin

31 October 2008 (has links)
D.Litt. et Phil. / The aim of this study was to determine possible relationships between sense of coherence, temperament and decision-making and to explore the nature of these relationships. The study was based on the assumption that people attempt to make sense of complex environments and that differences in certain biological and psychological characteristics may lead to differences in the way that people make decisions in complex environments. Temperament was defined as a biological or physiological aspect that influences human behaviour. Sense of coherence was conceptualised as a psychological, global orientation that influences the way in which individuals understand their environments and can therefore give rise to individual differences in behaviour. Decision-making style was defined as a specific behavioural manifestation of the manner in which individuals make sense of complex environments and it was postulated that decision-making would probably be influenced by temperament and sense of coherence. In order to explore the current study’s research questions, a sample of 189 third year and Honours students in Psychology at a tertiary institution was used. The ages of the participants ranged from 19 tot 34 years and the average age was 22 years. More women (91.5%) participated in the study than men (8.5%). As a result of practicalities it was impossible to use a random sample. Three self-report measurements were used to respectively measure sense of coherence, temperament and decision-making style. These were the Orientation to Life Questionnaire, Pavlovian Temperament Survey and Melbourne Decision Making Questionnaire. The Pavlovian Temperament Survey measures three characteristics of the nervous system namely Strength of Excitation, Strength of Inhibition and Mobility of the Nervous Processes. An additional sub-scale was added to measure Balance of the Nervous Processes. The Orientation to Life Questionnaire measures Comprehensibility, Manageability, Meaningfulness as well as total Sense of Coherence. The Melbourne Decision Making Questionnaire measures four decision-making styles: one effective style, Vigilance and three ineffective styles, Procrastination, Hypervigilance and Buck Passing. The raw data that were collected from the completed questionnaires were subjected to several statistical analyses. The data were tested for normality of sub-scale distributions, which lead to logistical regression analyses being used to determine if temperament and sense of coherence can predict differences in decision-making style. Pearson product moment correlations as well as canonical correlations were also used. Multiple analyses of variance were used to determine whether biographical variables could account for any differences in sense of coherence, temperament and decision-making style. The results indicated that differences due to language, year of study or work status did not affect scores with regard to sense of coherence, temperament or decision-making style. The sample could therefore be regarded as quite homogeneous and the effect of confounding variables could be limited. However, generalisability of the results was also compromised. It was found that Strength of Excitation, Strength of Inhibition and Mobility of the Nervous Processes displayed relationships with Sense of coherence as well as the individual aspects of sense of coherence namely Comprehensibility, Manageability and Meaningfulness. This finding points to the possibility that physiological responses and psychological assessment of complex environments are related. Even though Balance of the Nervous Processes was not indicated as related to sense of coherence, it was found that this characteristic of the nervous system may possibly relate to decision-making. In line with these findings, the results indicated the possibility of relationships between a person’s psychological assessment of situations and behavioural outcomes as relationships were found between sense of coherence and decision-making style. It was indicated that certain temperament dimensions possibly displays an inverse relationship with decision-making styles, and especially the use of a hypervigilant decision-making style. However, the role of temperament in the use of a vigilant decision-making style is unclear. Lastly, the results indicated that the emotional assessment of stimuli as meaningful and challenging may possibly give rise to the use of a vigilant decision-making style. The assessment of situations as chaotic and unstructured could possibly relate more to the use of ineffective decision-making styles. An overall conclusion that can be made is that relationships between sense of coherence, temperament and decision-making style do indeed exist but that the nature of the relationships is quite complex. It seems as if different mechanisms are at play with regard to determining the use of effective and ineffective decision-making styles. These mechanisms could possibly lie in the emotional and cognitive assessments of situations. It seems as if a healthy emotional assessment of situations as challenging and meaningful precede the use of an effective, cognitively-based decision-making style. The cognitive assessment of situations as chaotic and unstructured could possibly lead to a more emotional decision-making response and decisions may be postponed, its responsibility may be shifted or it may be handled in a panicky manner. The results of this study should be interpreted with care since the sample was quite homogeneous and not particularly large. The exclusive use of the Melbourne Decision Making Questionnaire to measure decision-making is also problematic and the inclusion of an objective measurement of decision-making efficiency would have been preferable. It is also unclear whether reported decision-making style is equal to true decision-making style. Lastly, it was also decided to move away from Antonovsky’s (1987) recommendations that sense of coherence be treated as one global construct and the individual sub-scales were analysed separately. Future research can make use of similar variables and statistical techniques with bigger and more diverse samples to facilitate the development of an explanatory model for behaviour within complex environments. If the same variables are used, other measurements should be included to expand the conceptual framework. Future research could also test the current findings in practice for example in training or therapy.
42

Generation of Transient Quantum Coherence Using Partially Coherent Radiation

Sadeq, Zaheen 26 November 2012 (has links)
We investigate quantum coherences between excited states induced on quantum systems upon excitation by partially coherent radiation sources. Attempts at rejuvenating coherences using noisy sources are also explored. This work is most relevant to studies of photo-excitation of light harvesting systems under natural conditions as well as to quantum optical experiments using partially coherent lasers. The transient coherent response of a model $V$ system upon irradiation by various models of incoherent light is explored and it was found that it was possible to induce transient excited state coherences upon excitation. These excited state coherences eventually become a small fraction of population and the system reaches a mixed state. Lastly, we critique an existing literature model of excitation by noisy laser and we show that the coherence observed in that scenario is artificial. We propose an alternative using a physical model of noisy excitation.
43

Generation of Transient Quantum Coherence Using Partially Coherent Radiation

Sadeq, Zaheen 26 November 2012 (has links)
We investigate quantum coherences between excited states induced on quantum systems upon excitation by partially coherent radiation sources. Attempts at rejuvenating coherences using noisy sources are also explored. This work is most relevant to studies of photo-excitation of light harvesting systems under natural conditions as well as to quantum optical experiments using partially coherent lasers. The transient coherent response of a model $V$ system upon irradiation by various models of incoherent light is explored and it was found that it was possible to induce transient excited state coherences upon excitation. These excited state coherences eventually become a small fraction of population and the system reaches a mixed state. Lastly, we critique an existing literature model of excitation by noisy laser and we show that the coherence observed in that scenario is artificial. We propose an alternative using a physical model of noisy excitation.
44

A Study on the Coherent Atomic Effects and Their Applications

Sun, Qingqing 2010 May 1900 (has links)
Coherent atomic states prepared by laser field can have quantum interference between the different transition amplitudes. Therefore, the medium susceptibility and optical response can be engineered, leading to many interesting phenomena, such as coherent population trapping (CPT), electromagnetically induced transparency (EIT), and lasing without inversion (LWI). We studied the coherence effects in various prototype atomic systems, and found many interesting applications. We solved the slow light bandwidth problem by decomposing the pulse and matching each frequency to its EIT window using a magnetic field gradient. We also considered the probe field deflection induced by the driving field distribution in EIT, and showed that even a broadband pulse can be deflected without serious spreading. In the fast light area, we examined the effects of noise and parameter deviations in a bichromatic Raman type white light cavity. Taking advantage of the adjustable absorption of EIT, we showed that EIT in a laser cavity can have either first-order or second-order phase transitions. Last but not least, we show that the adiabatic population transfer can be used to reverse the weak measurement of an arbitrary field with finite photon number.
45

Swept-frequency sampled grating distributed Bragg reflector lasers optimized for optical coherence tomography applications a thesis /

George, Brandon J. Derickson, Dennis. January 1900 (has links)
Thesis (M.S.)--California Polytechnic State University, 2009. / Mode of access: Internet. Title from PDF title page; viewed on Jan. 20, 2010. Major professor: Dr. Dennis Derickson. "Presented to the Electrical Engineering Department faculty of California Polytechnic State University, San Luis Obispo." "In partial fulfillment of the requirements for the degree [of] Master of Science in Electrical Engineering." "December, 2009." Includes bibliographical references (p. 111).
46

Detection and diagnosis of oral neoplasia with confocal microscopy and optical coherence microscopy

Clark, Anne Lauren. January 2003 (has links) (PDF)
Thesis (Ph. D.)--University of Texas at Austin, 2003. / Vita. Includes bibliographical references. Available also from UMI Company.
47

Electronic decoherence and nonadiabatic chemical dynamics in betaine dye molecules

Hwang, Hyonseok, January 2003 (has links) (PDF)
Thesis (Ph. D.)--University of Texas at Austin, 2003. / Vita. Includes bibliographical references. Available also from UMI Company.
48

Contrast agents for tumor detection with optical coherence tomography /

Zuluaga, Andrés Felipe, January 2000 (has links)
Thesis (Ph. D.)--University of Texas at Austin, 2000. / Vita. Includes bibliographical references (leaves 152-162). Available also in a digital version from Dissertation Abstracts.
49

Optical designs and image processing algorithms for optical coherence tomography detection of glaucoma

Wang, Bingqing 10 September 2015 (has links)
Optical Coherence Tomography (OCT) is an optical tomography technique which provides high resolution non-invasive three-dimensional (3D) structural images of the sample based on coherent properties of light. The dissertation focuses on the use of OCT systems for detecting glaucoma, which is the second leading cause of blindness worldwide. First, as a prerequisite of analyzing ophthalmologic OCT images, a retinal sublayer segmentation algorithm is presented and implemented with GPU assisted computation. Then, a polarization-sensitive optical coherence tomography (PS-OCT) system was constructed for the study of glaucoma. Three closely related clinical and animal studies on early-stage glaucoma detection using either OCT or PS-OCT were performed. Statistical analysis of the study results indicates that the scattering property of retinal nerve fiber layer (RNFL) is the earliest indicator for glaucoma. Finally, to investigate the scattering properties of RNFL, a pathlength-multiplexed scattering-angle-diverse optical coherence tomography (PM-SAD-OCT) system was designed and built. PM-SAD-OCT images were collected from human and rodent retina as well as earthworm nerve cord. PM-SAD-OCT system shows promising potentials to detect neurodegenerative diseases including glaucoma. / text
50

Electronic decoherence and nonadiabatic chemical dynamics in betaine dye molecules

Hwang, Hyonseok 28 August 2008 (has links)
Not available / text

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