A thesis submitted to the Faculty of Engineering and the Built Environment, University of the Witwatersrand, Johannesburg, in fulfilment of the requirements for the degree of Doctor of Philosophy. Johannesburg, 2016 / The theoretical and experimental investigation of electron spin-resonance relaxation to deposit thermal energy into liquid gadolinium-based contrast agents for cancer hyperthermia treatment is presented. Previous works suggest that using protons in water are inadequate, with a thermal deposition rate of approximately 1 ◦C per two years. A novel component of this research relies on the use of gadolinium-chelated molecules, which are currently used as contrast agents in clinical MRI scans. The chelating agents, or ligands, investigated are Gadobenate (MultiHance R ), Gadopentetate (Magnevist R ), Gadoterate (DotaremR ) and Gadoteridol (ProHance R ). The gadolinium atom has seven unpaired electrons in its inner f shell orbital and as a result has a 660 times stronger paramagnetic response when placed in an external magnetic field. The research tests the hypothesis that by using an appropriate external homogeneous DC magnetic field, together with a radiofrequency excited resonator, that a measurable amount of thermal energy is deposited into a liquid gadolinium-based contrast agent. The aim of this research is to ultimately discover a new cancer hyperthermia treatment. The research theory suggests that a temperature rate of 13.4 ◦C · s−1 can be achieved using the gadolinium-based contrast agents under certain experimental conditions, and a maximum of 29.4 ◦C · s−1 under more optimal conditions. The temperature rates are calculated using parameter values commonly found in literature and practice. The simulation and design of the DC magnetic field coil system is discussed, together with the simulation results and design parameters of the radiofrequency loop-gap resonator. The experimental results and analysis indicate that the selected contrast agents have varied responses based on their chemical nature and that only two out of the four contrast agents, Dotarem and ProHance, show a measurable effect albeit sufficiently small that statistical techniques were necessary to distinguish the effect from background. A model fit to the data is performed in order to determine the spin-lattice relaxation time of the contrast agents under the specified experimental conditions. The model estimate is significantly smaller than the values found in literature under similar conditions, with a spin-lattice relaxation time τ1e of approximately 0.2 ps compared to the literature value of 0.1 ns. Although the observed electron spin resonance heating rate is in the milli-Watt range it is still notably larger (167 000 times) compared to the heating rate obtained using protons. The low temperature rates suggest that a more suitable agent or molecule with a larger spin-relaxation time be used, in order to achieve clinical useful temperature rates in the range of 14 ◦C · s−1. / MT2017

As moléculas que compõem um fluído, devido à autodifusão, encontram-se em constante movimento de translação num meio poroso. Observar a migração dessas moléculas de um poro para outro é fundamental para análise das conectividades do meio, resultado importante para a prospecção de óleo e gás, qualidade de membranas filtros, entre outros processos. Se há distintos tempos de relaxações transversais, T2, para os poros, ocorre quando estes apresentam características físico-químicas ou tamanhos diferentes, um experimento capaz de observar esse efeito de troca entre poros é o chamado T2-T2 Exchange proposto em 1993. Esse experimento, na sua versão original, corresponde a um experimento tridimensional que consome muito tempo para ser executado, inviabilizando, por exemplo, o uso em perfilagem de poços petrolíferos. Desta forma, o grupo propôs diminuir o tempo de execução reduzindo uma dimensão do experimento. Este novo método, novo experimento, foi nomeado de T2-Filtered T2-T2 Exchange, o qual utiliza a primeira parte da sequência de pulsos original como um filtro de T2. Com o objetivo de validar o experimento proposto, surgiu a oportunidade de estudar a técnica T2-T2 Exchange como um todo. No decorrer do trabalho, surgiu mais uma nova aplicação da técnica T2-T2 Exchange, a execução simultânea. Tanto a versão tridimensional do T2-T2 Exchange quando a bidimensional, necessitam de uma ciclagem de fase especial. Neste contexto, foi proposto também a execução simultânea dos experimentos T2-Filtered T2-T2 Exchange e Saturation-Recovery-CPMG, adquirindo os sinais separados e empregando a ciclagem de fases distintas. A fim de validar as propostas T2-Filtered T2-T2 Exchange e execução simultânea, se optou por uma amostra padrão, uma cerâmica de alumina foi saturada com água e, então, estudado os núcleos de hidrogênios. A cerâmica foi manufaturada pelo método de prensagem a seco com adição de agentes porogênicos e sinterização, a qual foi caracterizada via porosimetria por intrusão de mercúrio e imagens por microscópio eletrônico de varredura. Em um campo de 2 tesla, frequência de 85 MHz para os núcleos de hidrogênios, foram executados os experimento Saturation-Recovery-CPMG, T2-T2 Exchange e T2-Filtered T2-T2 Exchange. A análise comparativa entre os mapas de correlação T1-T2 e as curvas de trocas obtidos deste, permitiu validar as propostas. Desta forma, se concluiu que a nova sequência T2-Filtered T2-T2 Exchange proposta, é uma poderosa ferramenta com potencial para aplicação em well-logging. / The molecules that make up a fluid inside a porous media are in constant motion due to self diffusion. Observing this migration inside the media is very interesting for analyzing the connectivity between different regions of the sample, which is of great importance to the field of oil and gas prospection. In the case the sample has pores with distinct transverse relaxation times, T2, which happens when they have distinct physical-chemical properties or sizes, an experiment capable of observing the movement from one distinct pore from the other is the T2-T2 Exchange proposed in 1993. This experiment, in its original version, corresponds to a three dimensional experiment which usually takes a very long time, making it unfeasible for well logging for example. Thus, this work proposes a method to drastically reduce the duration of the experiment by eliminating one of its dimensions. It was named T2-Filtered T2-T2 Exchange. It uses the first part of the original sequence as a T2 filter. To validate the filtered technique, the T2-T2 Exchange technique was vastly studied as a whole. Some phase cycling characteristics of the techniques were observed and in the end led to the development of new proposals. The proposal consists of simultaneously performing both the T2-Filtered T2-T2 Exchange and the Saturation-Recovery-CPMG. For the experimental tests of the sequences, a water saturated alumina ceramic sample was chosen as the standard sample. The ceramic was manufactured by a process of dry pressing with addition of some porogenic agents and followed by sinterization. The sample was characterized by mercury injection capillary pressure and scanning electron microscopy. The NMR experiments were performed on a 2 Tesla magnet corresponding to an 85 MHz frequency for protons and the experiments performed wereT2-T2 Exchange, T2-Filtered T2-T2 Exchange and Saturation-Recovery-CPMG. The comparative analysis between the T1-T2 correlation and the exchange curves obtained allowed the validation of the proposals. It was possible to conclude that the T2-Filtered T2-T2 Exchange technique is a powerful tool with potential application in the well-logging field.

The purpose of this study was to evaluate the thesis that matching locus of control with type of relaxation training enhances physiological self-control. This was accomplished by comparing the effectiveness of a somatic and a cognitive relaxation method for internal and external locus of control subjects. It was hypothesized that the two techniques vary in degree of cue salience, and that the attentional strategy of internals would interact with the cognitive approach while externals would respond better to the somatic approach. Subjects were 80 volunteers from stressful occupations who scored high on the State-Trait Anxiety Inventory A-trait scale. Forty internals and 40 externals as defined by extreme scores on the Adult Form Nowicki Strickland Locus of Control Scale were randomly assigned to either the Jacobson or Autogenic group for five weekly laboratory training sessions with daily home practice. The effectiveness of the relaxation training was measured by six dependent variables: EMG, skin temperature, heart rate, State-Trait Anxiety Inventory (A-state and A-trait scales), and self-reported home practice sessions. The data were analyzed by using analyses of variance with repeated measures. The expected interaction between locus of control and type of relaxation training was found only for heart rate. While the treatment was effective in reducing physiological and subjective anxiety for all subjects, internal locus of control subjects and those who received Jacobson training reduced muscle tension and increased temperature better than externals and subjects in the Autogenic group. Externals became more internal during training, and the allegedly stable characteristic of trait anxiety significantly decreased. The possibility that heart rate may be a less easily perceived parameter than EMG or skin temperature is discussed, and it is recommended that future research evaluate other physiological variables for enhanced responsivity under congruent conditions. The importance of further basic research on relaxation training is emphasized, and it is noted other aspects of this widely used treatment approach should be investigated for interactions with locus of control.

Plastic relaxation was observed in InᵡGa₁₋ᵡN/GaN epilayers grown on c-plane sapphire substrates. The relaxation obeys the universal hyperbolic relation between the strain and the reciprocal of the layer thickness. Plastic relaxation in this material system reveals that there is no discontinuous relaxation at critical thickness and once a layer starts to relieve, it follows the same strain-thickness dependence, unconstrained by the original misfit until the material system work hardens. From x-ray diffraction calibration, the in-plane and normal relaxation constants KP0 and KN0 for the InᵡGa₁₋ᵡN/GaN grown on sapphire were found to be −0.98 ± 0.03 and +0.51 ± 0.03 nm, respectively. / Singapore-MIT Alliance (SMA)

Thèse numérisée par la Division de la gestion de documents et des archives de l'Université de Montréal

The objective of this study is to characterize the long-term behavior of an austenitic-ferritic stainless steel-based pretensioned system for strengthening reinforced concrete bridge pier caps in shear. Stress relaxation experiments were conducted on UNS S32101 stainless steel bars subjected to various initial stresses and temperatures within the low homologous temperature (LHT) regime. Data from these experiments were used to develop a viscoplastic constitutive model to describe the long-term time- and temperature-dependent behavior of the stainless steel bars. This mechanics-based approach is integrated with an analytical method based on strut-and-tie analysis to compute the shear strength of reinforced concrete pier caps strengthened with this external pretensioned system.

Thesis (Ph.D.)--McMaster University (Canada), 1994. / Source: Dissertation Abstracts International, Volume: 56-08, Section: B, page: 4313. Adviser: A. D. Bain.

Mémoire (M.Ed.)-- Université du Québec à Chicoutimi, 1993. / Résumé disponible sur Internet. CaQCU Document électronique également accessible en format PDF. CaQCU

Traditional treatment for insomnia has been chemotherapy-- despite short-term value and side effects. Need for an alternative has led to research on behavioral treatment methods for insomnia. Relaxation training has consistently produced effective results, but the limited research on biofeedback and stimulus control suggests that they too may be viable alternate treatment methods. The present research investigated electromyogram (EMG) biofeedback, pseudo-EMG biofeedback, relaxation, training, and stimulus control as methods of treating sleep-onset insomnia. Volunteers consisting of 12 males and 24 females were recruited through newspaper advertisements. Subjects had no known physical cause for insomnia and were either free of sleeping medication or kept their dosage constant during the study. Subjects were matched for age and sex, randomly assigned to one of the four treatment groups, then randomly assigned to one of three therapists. Results indicated that pretreatment EMG scores for the four groups were high but not significantly different-- while post treatment EMG scores were not significantly reduced. Pretreatment sleep-latency measures were high, but not significantly different from each other. Post treatment latency measures were significantly reduced, but not significantly different from each other. Correlation between EMG-change scores and sleep-latency-change measures was non-significant. Pretreatment nightly awakenings for the four groups were not significantly different. Post treatment awakenings for the four groups were significantly reduced, but not significantly different from each other. There were not significant interactions for therapist or treatment with any of the dependent variables.

This study was designed to compare the clinical effectiveness of EMG biofeedback and progressive relaxation training in the treatment of muscle tension headache. These procedures also were compared with a treatment-element control group. Results from this study indicated that EMG biofeedback, progressive relaxation, and the control procedures all led to significant improvements across sessions on EMG and most self-report measures. There was little evidence that either treatment technique was superior to the other or to the control procedures. Although in most cases there were rather large numerical differences between groups, these differences generally were not statistically significant. Analysis of correlations between EMG and self-report data revealed a pattern of variable but generally nonsignificant relationships. However, for the biofeedback and progressive relaxation groups, there were a number of highly significant correlations. The pattern of correlations suggested that the relationship between EMG tension and subjective headache pain may be better predicted by something other than a strict linear model.