Typescript (photocopy) / vi, 219 leaves : ill. ; 31 cm / Title page, contents and abstract only. The complete thesis in print form is available from the University Library. / Thesis (Ph.D.)--Dept. of Oral Biology, University of Adelaide, 1983

Not available / text

CAPES / O presente trabalho descreve o desenvolvimento de uma técnica para a medição da bioimpedância de tecido animal através do uso de sistema de biotelemetria passiva, possuindo duas unidades sensoras, compostas por apenas um indutor e eletrodos, e duas unidades de leitura constituídas de uma bobina de leitura em série com um capacitor e um resistor (circuito RLC série). Esta técnica permite obter a parte real e imaginária da bioimpedância por meio da medição do módulo e da fase da impedância de entrada do sistema de biotelemetria proposto. A fim de melhor caracterizar o objeto de medição, alguns experimentos foram realizados, usando amostras de tecido animal post mortem (carne bovina), e os respectivos resultados são apresentados e comentados. Com base nestes resultados, o sistema de biotelemetria foi especificado e implementado. Com o intuito de validar a técnica de medição e o sistema de biotelemetria, foram utilizados modelos elétricos para representar a bioimpedância, levando a erros de medição inferiores a ± 4% para a parte real da bioimpedância. Experimentos foram conduzidos com o uso do sistema de biotelemetria e amostras de carne, embaladas a vácuo e com unidades sensoras inseridas. Como resultado, foi possível obter a razão entre duas partes reais da bioimpedância em duas freqüências distantes, denominada de parâmetro Py, e a taxa de anisotropia. O perfil da resposta de Py apresentou correlação com relação a resultados encontrados na literatura. Além disso, neste trabalho descreve-se também uma nova técnica de medição de fase entre dois sinais senoidais e um equipamento para a medição do módulo e da fase da impedância de entrada do sistema de biotelemetria. / This work describes the development of a technique for the measurement of the bioimpedance of animal tissues by means of a passive biotelemetric system, which is made up of two sensor units, each one composed of only an inductor and electrodes, and two reading units that consists of a reading coil in series with a capacitor and with a resistor (series RLC circuit). This technique allows the acquisition of the real and imaginary parts of the bioimpedance through the measurement of the module and phase parts of the input impedance of the proposed biotelemetric system. In order to characterize the object of measurement, some experiments were performed, employing post mortem animal tissue samples (bovine meat). The respective results are presented and discussed in details. Based in these results, the biotelemetric system was specified and implemented. With the purpose to validate the measurement technique and the biotelemetric system, bioimpedance models has been used, leading to measurement errors down to ± 4% to the real part of the bioimpedance. Experiments were carried out using the biotelemetric system and vacuum packed bovine meat samples with sensor units. As a result, it was possible to obtain the ratio between two real parts of the bioimpedance at two distant frequencies, also known as Py parameter, and the anisotropy ratio of meat samples. Besides that, this work also describes a novel simple method to measure the phase difference between two sinusoidal signals and an equipment to measure the module and phase of the input impedance of the biotelemetric system.

CAPES / O presente trabalho descreve o desenvolvimento de uma técnica para a medição da bioimpedância de tecido animal através do uso de sistema de biotelemetria passiva, possuindo duas unidades sensoras, compostas por apenas um indutor e eletrodos, e duas unidades de leitura constituídas de uma bobina de leitura em série com um capacitor e um resistor (circuito RLC série). Esta técnica permite obter a parte real e imaginária da bioimpedância por meio da medição do módulo e da fase da impedância de entrada do sistema de biotelemetria proposto. A fim de melhor caracterizar o objeto de medição, alguns experimentos foram realizados, usando amostras de tecido animal post mortem (carne bovina), e os respectivos resultados são apresentados e comentados. Com base nestes resultados, o sistema de biotelemetria foi especificado e implementado. Com o intuito de validar a técnica de medição e o sistema de biotelemetria, foram utilizados modelos elétricos para representar a bioimpedância, levando a erros de medição inferiores a ± 4% para a parte real da bioimpedância. Experimentos foram conduzidos com o uso do sistema de biotelemetria e amostras de carne, embaladas a vácuo e com unidades sensoras inseridas. Como resultado, foi possível obter a razão entre duas partes reais da bioimpedância em duas freqüências distantes, denominada de parâmetro Py, e a taxa de anisotropia. O perfil da resposta de Py apresentou correlação com relação a resultados encontrados na literatura. Além disso, neste trabalho descreve-se também uma nova técnica de medição de fase entre dois sinais senoidais e um equipamento para a medição do módulo e da fase da impedância de entrada do sistema de biotelemetria. / This work describes the development of a technique for the measurement of the bioimpedance of animal tissues by means of a passive biotelemetric system, which is made up of two sensor units, each one composed of only an inductor and electrodes, and two reading units that consists of a reading coil in series with a capacitor and with a resistor (series RLC circuit). This technique allows the acquisition of the real and imaginary parts of the bioimpedance through the measurement of the module and phase parts of the input impedance of the proposed biotelemetric system. In order to characterize the object of measurement, some experiments were performed, employing post mortem animal tissue samples (bovine meat). The respective results are presented and discussed in details. Based in these results, the biotelemetric system was specified and implemented. With the purpose to validate the measurement technique and the biotelemetric system, bioimpedance models has been used, leading to measurement errors down to ± 4% to the real part of the bioimpedance. Experiments were carried out using the biotelemetric system and vacuum packed bovine meat samples with sensor units. As a result, it was possible to obtain the ratio between two real parts of the bioimpedance at two distant frequencies, also known as Py parameter, and the anisotropy ratio of meat samples. Besides that, this work also describes a novel simple method to measure the phase difference between two sinusoidal signals and an equipment to measure the module and phase of the input impedance of the biotelemetric system.

Thesis: Ph. D., Massachusetts Institute of Technology, Department of Nuclear Engineering, 1977 / Bibliography : leaves 169-175. / Ph. D. / Ph. D. Massachusetts Institute of Technology, Department of Nuclear Engineering

A high performance liquid chromatographic (HPLC) system consisting of a binary mobile phase, a µBondapak C₁₈ column, and a fluorescence detector was used to separate the B-6 vitamers pyridoxal (PL), pyridoxine CPN), and pyridoxamine (PM) as well as the internal standard deoxypyridoxine. An extraction procedure, compatible with the HPLC system, was developed to isolate the B-6 vitamers from rat livers, kidneys, and brains. PL values were derived from the sum of tissue PL and pyridoxal phosphate (PLP), the latter having been dephosphorylated to PL. Similarly, PN values were the sum of tissue PN and pyridoxine phosphate (PNP) and PM data the sum of PM and pyridoxamine phosphate (PMP). Separation and quantitation of tissue vitamers were successful and reflected significant relationships between rat vitamin B-6 intakes and tissue concentrations of the B-6 vitamers PL and PM as well as total B-6 vitamer concentration. PM was found to be the major vitamer in all tissues. The HPLC data were compared to values obtained by the AOAC microbiological (MB) assay performed on the same samples. Significant correlations (r) ranging from 0.31 - 0.73 for PL, 0.30 - 0.47 for PM, and 0.48 - 0.55 for total B-6 vitamer concentration were observed between values obtained via the methods. Both HPLC and MB vitamer data approximated reported values. The HPLC method offered the advantages of relative speed and simplicity. / M.S.

Thesis (M. Tech.) - Central University of Technology, Free State, 2006 / Electron microscopy plays an important role in diagnostic histopathology. When this investigation is anticipated, extra tissue is submitted directly for electron microscopy. However, often it is decided only later in a problematic case to perform this investigation and then the only tissue available is embedded in the routine laboratory’s paraffin block. This tissue has to be retrieved from the wax and this entails using a clearing agent before the rest of the electron microscopy method can be implemented. Traditionally xylene is the agent that is used but has the disadvantage of being extremely toxic. This study compared the morphological effects of a relatively new and non toxic clearing agent, Tissueclear®, with that of xylene. Exposure of tissue to clearing agents for 30 minutes and overnight was performed to assess whether Tissueclear® gave better results in the long term than xylene, in the hope that the laboratory turn around time could be improved and the amount of toxic reagents used in the EM laboratory will be reduced. A second part of the study involved a questionnaire submitted to laboratory staff to assess their knowledge of xylene toxicity. Of the 325 cases submitted for electron microscopy at Universitas Hospital between January 2004 and July 2005, 140 of these had to be retrieved from paraffin wax. Four specimens were prepared from each case. Two were processed in xylene for 30 minutes and overnight and two in Tissueclear® for 30 minutes and overnight. The specimens were evaluated for consistency and resin compaction as well as ultrastructural preservation of the cell membrane, cytoplasmic content and extracellular material. The results showed that Tissueclear® and xylene gave comparable results after 30 minutes and that Tissueclear® was superior after overnight processing. This meant that a specimen submitted for electron microscopy would be processed immediately without waiting for the following morning as was the case with xylene and that the processing time for such a specimen had been shortened from 3 to 2 days. It also meant that the laboratory staff was exposed to one less toxic reagent. The results on the questionnaire showed that there were large areas of ignorance regarding toxicity as well as appropriate safety procedures that need to be followed in the laboratory. It is hoped that this study will improve awareness in this regard and encourage the use of other newer less toxic reagents.

The computer-aided analysis is poised to play an increasingly prominent role in medicine and healthcare. Benefiting from the increasing computing power, various machine learning frameworks have been developed in the biomedical field, bringing significant improvements in real-world clinical applications. However, for many diseases, the development of these life-supporting algorithms is still in its infancy. To bridge this gap: This thesis is dedicated to the development of efficient algorithms for better image intervention and addressing data quality challenges in machine learning algorithms to provide direct guidance for real-world clinical applications. With the above goals, three topics are explored in depth. First, we develop a novel tissue analysis framework for cardiac substrate identification and tissue heterogeneity assessment. In particular, we creatively used model uncertainty to measure tissue structure information, offering a means of extracting the tissue heterogeneity information in a non-invasive way for real-time imaging and processing. The tissue analysis framework in the first aim is based on the fully supervised technique, which relies heavily on the availability of large-scale datasets with accurate annotations. Such high-quality datasets are extremely time-consuming to acquire, especially for biomedical segmentation tasks. To lessen the need for the labeling process, we further develop three weakly supervised learning frameworks to address data and labeling challenges caused by limited data resources. Finally, we develop an in-vivo tissue analysis framework on cardiac datasets, aiming to provide real-time guidance for clinical ablation procedures. Our models could contribute to the improvement of ablation treatment by identifying the ablation targets and avoiding critical structures within the hearts.

A aplicação de corrente elétrica na pele humana estimula alguns dos nervos periféricos e fibras do corpo humano, causando diversas reações tais como o aumento da produção de suor. Além disso, a análise dessas reações pode ser usada para diagnosticar doenças como diabetes. No entanto, grande parte dos aparelhos de estimulação elétrica comerciais utilizam sinais de onda quadrada. Esses sinais não são ideais uma vez que estimulam não somente as glândulas desejadas (fibras C), mas também as fibras A-delta do corpo, responsáveis pela sensação rápida de dor. Neste contexto, este trabalho apresenta o desenvolvimento de um sistema eletrônico para controlar a estimulação elétrica da pele humana. O objetivo do sistema é tornar possível o teste diferentes padrões de pulsos de corrente elétrica, a fim de obter a forma ideal para maximizar os efeitos desejados com um mínimo de dor. Como resultado do projeto tem-se o desenvolvimento de um dispositivo eletrônico microcontrolado que gera pulsos elétricos baseados em sinais pré-programados recebidos de um PC via USB. Além disso, o sistema é capaz de medir o valor da impedância da pele durante a estimulação elétrica, o que pode complementar o processo de diagnóstico. Os resultados dos testes realizados com o sistema mostraram que a intensidade da dor durante a estimulação pode ser minimizada apenas com a forma do pulso, sem a alteração da amplitude e da energia do sinal. Além disso, uma pequena diferença na impedância da pele foi observada quando diferentes formas de onda foram aplicadas. / It has been found that electrical current applied to the human skin stimulates some of the peripheral nerves and fibers of the human body, causing several reactions such as the increase of sweat production. Moreover the analyses of such reactions can be used to diagnose some diseases, for example diabetes. Nevertheless, most of the electrical stimulation devices, which use mostly square wave signals, are not optimal since they stimulate not only the desired glands (C-fiber) but also the Aδ-fibers of the body, responsible for the fast pain sensation. In this context, this work presents the development of a microcontroller based electronic system for controlling the electrical stimulation of human skin. The objective of the system was to make it possible to test different patterns of electric current pulses, in order to obtain the ideal shape for maximizing the desired stimulation effects with minimal pain. The result of the project was an electronic device that generates electrical pulses based on pre-programmed signals, which are received through a USB interface from a PC. Moreover the system was able to measure the skin impedance value during the electrical stimulation, complementing the diagnosis. The results of the tests carried out with the system showed that the pain intensity during the stimulation could be minimized according to the pulse shape not changing the amplitude and energy of the signal. Moreover a slight difference in the skin impedance was observed when different shapes were applied.

A aplicação de corrente elétrica na pele humana estimula alguns dos nervos periféricos e fibras do corpo humano, causando diversas reações tais como o aumento da produção de suor. Além disso, a análise dessas reações pode ser usada para diagnosticar doenças como diabetes. No entanto, grande parte dos aparelhos de estimulação elétrica comerciais utilizam sinais de onda quadrada. Esses sinais não são ideais uma vez que estimulam não somente as glândulas desejadas (fibras C), mas também as fibras A-delta do corpo, responsáveis pela sensação rápida de dor. Neste contexto, este trabalho apresenta o desenvolvimento de um sistema eletrônico para controlar a estimulação elétrica da pele humana. O objetivo do sistema é tornar possível o teste diferentes padrões de pulsos de corrente elétrica, a fim de obter a forma ideal para maximizar os efeitos desejados com um mínimo de dor. Como resultado do projeto tem-se o desenvolvimento de um dispositivo eletrônico microcontrolado que gera pulsos elétricos baseados em sinais pré-programados recebidos de um PC via USB. Além disso, o sistema é capaz de medir o valor da impedância da pele durante a estimulação elétrica, o que pode complementar o processo de diagnóstico. Os resultados dos testes realizados com o sistema mostraram que a intensidade da dor durante a estimulação pode ser minimizada apenas com a forma do pulso, sem a alteração da amplitude e da energia do sinal. Além disso, uma pequena diferença na impedância da pele foi observada quando diferentes formas de onda foram aplicadas. / It has been found that electrical current applied to the human skin stimulates some of the peripheral nerves and fibers of the human body, causing several reactions such as the increase of sweat production. Moreover the analyses of such reactions can be used to diagnose some diseases, for example diabetes. Nevertheless, most of the electrical stimulation devices, which use mostly square wave signals, are not optimal since they stimulate not only the desired glands (C-fiber) but also the Aδ-fibers of the body, responsible for the fast pain sensation. In this context, this work presents the development of a microcontroller based electronic system for controlling the electrical stimulation of human skin. The objective of the system was to make it possible to test different patterns of electric current pulses, in order to obtain the ideal shape for maximizing the desired stimulation effects with minimal pain. The result of the project was an electronic device that generates electrical pulses based on pre-programmed signals, which are received through a USB interface from a PC. Moreover the system was able to measure the skin impedance value during the electrical stimulation, complementing the diagnosis. The results of the tests carried out with the system showed that the pain intensity during the stimulation could be minimized according to the pulse shape not changing the amplitude and energy of the signal. Moreover a slight difference in the skin impedance was observed when different shapes were applied.