955 resultados para Highway-railroad grade crossings


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Mémoire numérisé par la Division de la gestion de documents et des archives de l'Université de Montréal

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Blends of chlorobutyl rubber (CIIR) with two grades of ethylene-propylene diene monomer rubber (EPDM) were prepared and the effect of blend ratio on the cure characteristics, hot air ageing resistance, steam ageing resistance, and mechanical properties were evaluated. The blend of CIIR with EPDM grade 301 T showed additive behavior and the blend with the other grade of EPDM (NDR 4640) showed synergistic behavior.

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Cerebral glioma is the most prevalent primary brain tumor, which are classified broadly into low and high grades according to the degree of malignancy. High grade gliomas are highly malignant which possess a poor prognosis, and the patients survive less than eighteen months after diagnosis. Low grade gliomas are slow growing, least malignant and has better response to therapy. To date, histological grading is used as the standard technique for diagnosis, treatment planning and survival prediction. The main objective of this thesis is to propose novel methods for automatic extraction of low and high grade glioma and other brain tissues, grade detection techniques for glioma using conventional magnetic resonance imaging (MRI) modalities and 3D modelling of glioma from segmented tumor slices in order to assess the growth rate of tumors. Two new methods are developed for extracting tumor regions, of which the second method, named as Adaptive Gray level Algebraic set Segmentation Algorithm (AGASA) can also extract white matter and grey matter from T1 FLAIR an T2 weighted images. The methods were validated with manual Ground truth images, which showed promising results. The developed methods were compared with widely used Fuzzy c-means clustering technique and the robustness of the algorithm with respect to noise is also checked for different noise levels. Image texture can provide significant information on the (ab)normality of tissue, and this thesis expands this idea to tumour texture grading and detection. Based on the thresholds of discriminant first order and gray level cooccurrence matrix based second order statistical features three feature sets were formulated and a decision system was developed for grade detection of glioma from conventional T2 weighted MRI modality.The quantitative performance analysis using ROC curve showed 99.03% accuracy for distinguishing between advanced (aggressive) and early stage (non-aggressive) malignant glioma. The developed brain texture analysis techniques can improve the physician’s ability to detect and analyse pathologies leading to a more reliable diagnosis and treatment of disease. The segmented tumors were also used for volumetric modelling of tumors which can provide an idea of the growth rate of tumor; this can be used for assessing response to therapy and patient prognosis.

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Low grade and High grade Gliomas are tumors that originate in the glial cells. The main challenge in brain tumor diagnosis is whether a tumor is benign or malignant, primary or metastatic and low or high grade. Based on the patient's MRI, a radiologist could not differentiate whether it is a low grade Glioma or a high grade Glioma. Because both of these are almost visually similar, autopsy confirms the diagnosis of low grade with high-grade and infiltrative features. In this paper, textural description of Grade I and grade III Glioma are extracted using First order statistics and Gray Level Co-occurance Matrix Method (GLCM). Textural features are extracted from 16X16 sub image of the segmented Region of Interest(ROI) .In the proposed method, first order statistical features such as contrast, Intensity , Entropy, Kurtosis and spectral energy and GLCM features extracted were showed promising results. The ranges of these first order statistics and GLCM based features extracted are highly discriminant between grade I and Grade III. In this study which gives statistical textural information of grade I and grade III Glioma which is very useful for further classification and analysis and thus assisting Radiologist in greater extent.

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Objectives: To evaluate the prophylactic efficacy of the human papillomavirus (HPV) quadrivalent vaccine in preventing low grade cervical, vulvar, and vaginal intraepithelial neoplasias and anogenital warts (condyloma acuminata). Design: Data from two international, double blind, placebo controlled, randomised efficacy trials of quadrivalent HPV vaccine (protocol 013 (FUTURE I) and protocol 015 (FUTURE II)). The trials were to be 4 years in length, and the results reported are from final study data of 42 months' follow-up. Setting: Primary care centres and university or hospital associated health centres in 24 countries and territories around the world. Participants: 17 622 women aged 16-26 years enrolled between December 2001 and May 2003. Major exclusion criteria were lifetime number of sexual partners (>4), history of abnormal cervical smear test results, and pregnancy. Intervention: Three doses of quadrivalent HPV vaccine (for serotypes 6, 11, 16, and 18) or placebo at day 1, month 2, and month 6. Main outcome measures: Vaccine efficacy against cervical, vulvar, and vaginal intraepithelial neoplasia grade I and condyloma in a per protocol susceptible population that included subjects who received all three vaccine doses, tested negative for the relevant vaccine HPV types at day 1 and remained negative through month 7, and had no major protocol violations. Intention to treat, generally HPV naive, and unrestricted susceptible populations were also studied. Results: In the per protocol susceptible population, vaccine efficacy against lesions related to the HPV types in the vaccine was 96% for cervical intraepithelial neoplasia grade I (95% confidence interval 91% to 98%), 100% for both vulvar and vaginal intraepithelial neoplasia grade I (95% CIs 74% to 100%, 64% to 100% respectively), and 99% for condyloma (96% to 100%). Vaccine efficacy against any lesion (regardless of HPV type) in the generally naive population was 30% (17% to 41%), 75% (22% to 94%), and 48% (10% to 71%) for cervical, vulvar, and vaginal intraepithelial neoplasia grade I, respectively, and 83% (74% to 89%) for condyloma. Conclusions: Quadrivalent HPV vaccine provided sustained protection against low grade lesions attributable to vaccine HPV types (6, 11, 16, and 18) and a substantial reduction in the burden of these diseases through 42 months of follow-up. Trial registrations: NCT00092521 and NCT00092534.

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La ciencia no es solo un conjunto de conocimientos acumulados, sino también una forma activa de aprender sobre el mundo que nos rodea. La forma en que se adquieren los conocimientos sobre la naturaleza del mundo está en el fondo del proceso de investigación, y constituye un modelo de aprendizaje recomendado y respaldado por unas normas nacionales sobre educación de la ciencia. En este texto se pueden encontrar la secuencia de experiencias que forman la investigación en ciencias.

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La ciencia no es solo un conjunto de conocimientos acumulados, sino también una forma activa de aprender sobre el mundo que nos rodea. La forma en que se adquieren los conocimientos sobre la naturaleza del mundo está en el fondo del proceso de investigación, y constituye un modelo de aprendizaje recomendado y respaldado por unas normas nacionales sobre educación de la ciencia. En este texto se pueden encontrar la secuencia de experiencias que forman la investigación en ciencias.

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La ciencia no es solo un conjunto de conocimientos acumulados, sino también una forma activa de aprender sobre el mundo que nos rodea. La forma en que se adquieren los conocimientos sobre la naturaleza del mundo está en el fondo del proceso de investigación, y constituye un modelo de aprendizaje recomendado y respaldado por unas normas nacionales sobre educación de la ciencia. En este texto se puede encontrar la secuencia de experiencias que forman la investigación en ciencias.

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La ciencia no es solo un conjunto de conocimientos acumulados, sino también una forma activa de aprender sobre el mundo que nos rodea. La forma en que se adquieren los conocimientos sobre la naturaleza del mundo está en el fondo del proceso de investigación, y constituye un modelo de aprendizaje recomendado y respaldado por unas normas nacionales sobre educación de la ciencia. En este texto se pueden encontrar la secuencia de experiencias que forman la investigación en ciencias.

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La ciencia no es solo un conjunto de conocimientos acumulados, sino también una forma activa de aprender sobre el mundo que nos rodea. La forma en que se adquieren los conocimientos sobre la naturaleza del mundo está en el fondo del proceso de investigación, y constituye un modelo de aprendizaje recomendado y respaldado por unas normas nacionales sobre educación de la ciencia. En este texto se pueden encontrar la secuencia de experiencias que forman la investigación en ciencias.

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La ciencia no es solo un conjunto de conocimientos acumulados, sino también una forma activa de aprender sobre el mundo que nos rodea. La forma en que se adquieren los conocimientos sobre la naturaleza del mundo está en el fondo del proceso de investigación, y constituye un modelo de aprendizaje recomendado y respaldado por unas normas nacionales sobre educación de la ciencia. En este texto se pueden encontrar la secuencia de experiencias que forman la investigación en ciencias.

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