Thesis (Ph. D.)--University of Washington, 2001. / Vita. Includes bibliographical references (p. 231-238).

Thesis (Ph.D.)--Virginia Commonwealth University, 2010. / Prepared for: Dept. of Biostatistics. Title from resource description page. Includes bibliographical references.

Thesis (Ph. D.)--University of Washington, 2004. / Vita. Includes bibliographical references (p. 91-94).

No description available.

The goal of this study was to show that quantifiable metabolic changes may be used to screen for cancer. NIH III nude mice (n=22) were injected with human GBM cells, with daily urine samples collected pre and post-injection. 14 mice were injected with saline to serve as controls. The measurement of metabolite concentrations took place on an 800 MHz NMR spectrometer. 34 metabolites were identified and quantified, through targeted profiling, with Chenomx Suite 5.1. Univariate statistical analysis showed that 3 metabolites (2-oxoglutarate, glucose and trimethylamine n-oxide) were significantly altered in the presence of tumour, while PCA and PLS-DA models found the maximum variance between the healthy and tumour-bearing groups. Receiver operating characteristic (ROC) curve analysis was applied to the data set to provide a measure of clinical utility. ROC statistics were as high as 0.85 for the analysis of individual metabolites, 0.939 for the analysis of metabolite pairs and 0.996 for PLS-DA models. These results show that metabolomics has potential as a screening tool for cancer. / Medical Physics

Over the past few decades, visualization and application researchers have been investigating vortices and have developed several algorithms for detecting vortex-like structures in the flow. These techniques can adequately identify vortices in most computational datasets, each with its own degree of accuracy. However, despite these efforts, there still does not exist an entirely reliable vortex detection method that does not require significant user intervention. The objective of this research is to solve this problem by introducing a novel vortex analysis technique that provides more accurate results by optimizing the threshold for several computationally-efficient, local vortex detectors, before merging them using the Bayesian method into a more robust detector that assimilates global domain knowledge based on labeling performed by an expert. Results show that when choosing the threshold well, combining the methods does not improve accuracy; whereas, if the threshold is chosen poorly, combining the methods produces significant improvement.

No description available.

Thesis (Ph. D.)--University of Washington, 2005. / Vita. Includes bibliographical references (p. 173-178).

Orientador: Guilherme Monteiro Tosoni / Dissertação (mestrado) - Universidade Estadual de Campinas, Faculdade de Odontologia de Piracicaba / Made available in DSpace on 2018-08-08T15:57:15Z (GMT). No. of bitstreams: 1 Melo_DanielaPitade_M.pdf: 2421264 bytes, checksum: 450ce050ad326e2d47d3b89064367748 (MD5) Previous issue date: 2007 / Resumo: O objetivo, neste trabalho, foi verificar se tempos alternativos de dessensibilização das placas de fósforo do sistema DenOptix causam interferência na qualidade da imagem radiográfica e no diagnóstico de cáries proximais. Foram obtidas imagens de 10 phantoms, constituídos de dentes humanos, utilizando-se placas de fósforo parcialmente dessenbilizadas. Os dez tempos de dessensibilização estudados foram em ordem decrescente: 130s, 98s, 66s, 34s, 25s, 20s, 15s, 10s, 5s e 0s. As imagens foram posteriormente avaliadas, quanto à sua qualidade subjetiva, por dois examinadores. Cada avaliador atribuiu escores para contraste, densidade e nitidez da imagem; para definição das estruturas - esmalte, dentina e junção amelo-dentinária; e para a presença ou ausência de imagem dupla. Os resultados foram submetidos à correlação de Spearman, análise de variância e teste de Tukey. Os tempos de 20s a 130s apresentaram qualidade satisfatória em todos os quesitos abordados. Após esta primeira avaliação, os seis tempos considerados estatisticamente eficazes nos quesitos referentes à qualidade geral da imagem foram submetidos a uma nova avaliação, quanto à presença de cárie proximal. As imagens correspondentes aos tempos selecionados foram interpretadas por cinco avaliadores. Cada avaliador atribuiu um escore para cada uma das faces dentárias interpretadas. Esses escores foram posteriormente comparados ao padrão ouro. Os tempos de dessensibilização alternativos foram avaliados, quanto à sua acurácia no diagnóstico de cárie, por meio da curva ROC. As médias das curvas ROC correspondentes aos tempos de dessensibilização avaliados variaram de 0,61 a 0,66 e não apresentaram diferença estatística significativa entre elas. O desempenho dos tempos de dessensibilização alternativos de 20s a 130s foi satisfatório tanto nos quesitos de qualidade geral da imagem como no diagnóstico de cáries proximais, demonstrando a possibilidade da utilização de tempos alternativos de dessensibilização das placas do sistema DenOptix na redução do tempo de trabalho na clínica diária / Abstract: The aim on this study was to verify if DenOptix¿s phosphor plates alternative erasing times would cause any influence on the image quality and on the diagnosis of approximal caries. Ten human teeth phantoms were radiographed using phosphor plates, partially erased. The chosen erasing times were: 130s, 98s, 66s, 34s, 25s, 20s, 15s, 10s, 5s e 0s. Two observers, independently, evaluated the general quality of each image, scoring the images on contrast, density, sharpness and structures definition (enamel, dentine and enamel-dentine junction). The presence of double image was also evaluated. The resultant data was evaluated using the Spearmen¿s correlation, variance analysis, and Tukey¿s test. The erasing times from 20s to 130s had a satisfactory quality in all the evaluated items. After the first evaluation, the erasing times that showed statistical efficiency in the evaluated quality items of the image went through another evaluation regarding the presence of approximal caries. The images of the selected erasing times were evaluated by five observers. Each observer scored the approximal surfaces of each tooth. The scores were compared to the golden standard. The alternative erasing times were evaluated by their accuracy on predicting caries by means of the ROC curve analysis. The means of the ROC curves of each erasing time evaluated varied from 0,61 to 0,66 and did not show significant statistical difference between them. The alternative erasing times from 20s to 130s was satisfactory both on the quality analysis as on approximal caries diagnosis, what makes the use of those alternative erasing times of DenOptix¿s phosphor plates feasible during clinical practice / Mestrado / Radiologia Odontologica / Mestre em Radiologia Odontológica

<p> The accuracy of a diagnostic test is often evaluated with the measures of sensitivity and specificity and the joint dependence between these two measures is captured by the receiver operating characteristic (ROC) curve. To combine multiple testing results from studies that are assumed to follow the same underlying probability law, a smooth summary receiver operating characteristic (SROC) curve can be fitted. Moses et al. (1993) proposed a least squares approach to fit the smooth SROC curve. </p> <p> In this thesis we overview the summary measures for the ROC curve in single study data as well as the summary statistics for the SROC curves in meta-analysis. These summary statistics include, the area under the curve (AUC), Q* statistic, area swept under the curve (ASC) and the partial area under the curve (pAUC). </p> <p> Our focus, however is mainly on the partial area under the SROC curve as it is being used frequently in meta-analysis of diagnostic testing. The appeal to use the pAUC instead of the full AUC is that the partial area can be used to focus on a clinically relevant region of the SROC curve where false positive rate (FPR) is small. Simulations and considerations for the use of the summary indices of the ROC and SROC curves are presented here. </p> / Thesis / Master of Science (MSc)