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Dissertations / Theses on the topic 'External validation'

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Published: 4 June 2021
Last updated: 28 September 2024

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1

Belding, Jennifer Nicole. "The Embodiment of External Objects: A Self-Validation Perspective." The Ohio State University, 2011. http://rave.ohiolink.edu/etdc/view?acc_num=osu1306892108.

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2

Franco, Ximena. "External validation of comorbid patterns of anxiety disorders in youth." FIU Digital Commons, 2003. http://digitalcommons.fiu.edu/etd/3409.

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This study examined the external validity of comorbidity among anxiety disorders in youth to determine whether specific comorbid conditions (e.g., anxiety disorder externalizing disorders) convey unique information when compared to "pure" anxiety disorder. The sample consisted of 329 youth and their parents who presented to the Child Anxiety and Phobia Program housed within the Child and Family Psychosocial Research Center at Florida International University. Youth were diagnosed using the Anxiety Disorders Interview Schedule for DSMIV: Child and Parent versions (ADIS for DSM-IV: C/P). In addition, questionnaire batteries were administered to assess external validation criteria. Statistically significant differences were found across all measures when comparing a pure anxiety disorder with all the different conditions. The findings suggest that there may be differential meaningfulness in having a single diagnosis of anxiety disorders versus different comorbid patterns. The findings are discussed with respect to theoretical and clinical implications of the current nosological system.
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Truong, Thanh. "Main-Memory Query Processing Utilizing External Indexes." Doctoral thesis, Uppsala universitet, Avdelningen för datalogi, 2016. http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-280374.

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Many applications require storage and indexing of new kinds of data in main-memory, e.g. color histograms, textures, shape features, gene sequences, sensor readings, or financial time series. Even though, many domain index structures were developed, very a few of them are implemented in any database management system (DBMS), usually only B-trees and hash indexes. A major reason is that the manual effort to include a new index implementation in a regular DBMS is very costly and time-consuming because it requires integration with all components of the DBMS kernel. To alleviate this, there are some extensible indexing frameworks. However, they all require re-engineering the index implementations, which is a problem when the index has third-party ownership, when only binary code is available, or simply when the index implementation is complex to re-engineer. Therefore, the DBMS should allow including new index implementations without code changes and performance degradation. Furthermore, for high performance the query processor needs knowledge of how to process queries to utilize plugged-in index. Moreover, it is important that all functionalities of a plugged-in index implementation are correct. The extensible main memory database system (MMDB) Mexima (Main-memory External Index Manager) addresses these challenges. It enables transparent plugging in main-memory index implementations without code changes. Index specific rewrite rules transform complex queries to utilize the indexes. Automatic test procedures validate the correctness of them based on user provided index meta-data. Moreover, the same optimization framework can also optimize complex queries sent to a back-end DBMS by exposing hidden indexes for its query optimizer. Altogether, Mexima is a complete and extensible platform for transparently index integration, utilization, and evaluation.
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Kataoka, Yuki. "External validation of prognostic indices for overall survival of malignant pleural mesothelioma." Kyoto University, 2019. http://hdl.handle.net/2433/245296.

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Fernandes, Ana Sofia Fachada. "Prognostic modelling of breast cancer patients: a benchmark of predictive models with external validation." Doctoral thesis, Faculdade de Ciências e Tecnologia, 2010. http://hdl.handle.net/10362/5087.

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Dissertação apresentada para obtenção do Grau de Doutor em Engenharia Electrotécnica e de Computadores – Sistemas Digitais e Percepcionais pela Universidade Nova de Lisboa, Faculdade de Ciências e Tecnologia
There are several clinical prognostic models in the medical field. Prior to clinical use, the outcome models of longitudinal cohort data need to undergo a multi-centre evaluation of their predictive accuracy. This thesis evaluates the possible gain in predictive accuracy in multicentre evaluation of a flexible model with Bayesian regularisation, the (PLANN-ARD), using a reference data set for breast cancer, which comprises 4016 records from patients diagnosed during 1989-93 and reported by the BCCA, Canada, with follow-up of 10 years. The method is compared with the widely used Cox regression model. Both methods were fitted to routinely acquired data from 743 patients diagnosed during 1990-94 at the Christie Hospital, UK, with follow-up of 5 years following surgery. Methodological advances developed to support the external validation of this neural network with clinical data include: imputation of missing data in both the training and validation data sets; and a prognostic index for stratification of patients into risk groups that can be extended to non-linear models. Predictive accuracy was measured empirically with a standard discrimination index, Ctd, and with a calibration measure, using the Hosmer-Lemeshow test statistic. Both Cox regression and the PLANN-ARD model are found to have similar discrimination but the neural network showed marginally better predictive accuracy over the 5-year followup period. In addition, the regularised neural network has the substantial advantage of being suited for making predictions of hazard rates and survival for individual patients. Four different approaches to stratify patients into risk groups are also proposed, each with a different foundation. While it was found that the four methodologies broadly agree, there are important differences between them. Rules sets were extracted and compared for the two stratification methods, the log-rank bootstrap and by direct application of regression trees, and with two rule extraction methodologies, OSRE and CART, respectively. In addition, widely used clinical breast cancer prognostic indexes such as the NPI, TNM and St. Gallen consensus rules, were compared with the proposed prognostic models expressed as regression trees, concluding that the suggested approaches may enhance current practice. Finally, a Web clinical decision support system is proposed for clinical oncologists and for breast cancer patients making prognostic assessments, which is tailored to the particular characteristics of the individual patient. This system comprises three different prognostic modelling methodologies: the NPI, Cox regression modelling and PLANN-ARD. For a given patient, all three models yield a generally consistent but not identical set of prognostic indices that can be analysed together in order to obtain a consensus and so achieve a more robust prognostic assessment of the expected patient outcome.
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Nacke, Filip. "External validation of a tool to assess medication-related admissions in four Swedish hospitals." Thesis, Uppsala universitet, Avdelningen för farmakokinetik och läkemedelsterapi, 2019. http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-388549.

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External validation of a tool to assess medication-related admissions in four Swedish hospitals Background The MedBridge trial is a large ongoing clinical trial on medication reviews in elderly patients in Sweden with participating hospitals from Uppsala, Enköping, Västerås and Gävle. A tool for assessing medication-related admissions (MRAs) has been developed and validated in Uppsala: Assessment Tool for identifying Hospital Admissions Related to Medications (AT-HARM10). MRAs is often used as an outcome for medication reviews and similar interventions. Validation of AT-HARM10 outside of Uppsala is therefore warranted. Aim The aim was to externally validate AT-HARM10. This was needed since AT-HARM10 was for the first time used outside Uppsala. Materials and methods The readmissions of elderly patients within the MedBridge trial were collected from all participating hospitals. The assessors in this study were two final-year pharmacy students. First, the assessors assessed the readmissions independently of each other and then a consensus meeting was held where the readmissions were discussed, and a consensus was reached. The outcomes in this study were the assessment time, inter-rater reliability and content validity between the hospitals from Uppsala, Enköping, Västerås, and Gävle. The time was measured every day during the assessment period. The inter-rater reliability was calculated for every consensus meeting. The content validity was based on the questions from AT-HARM10 and was collected for each of the assessed readmissions and compared between the four participating hospitals. The content validity of the distribution of questions U1-P10 between the hospitals was tested with a χ2-test. Results In this study, 1687 unplanned readmissions from 893 patients were assessed. Uppsala University Hospital had 6.6 minutes as total mean assessment time including consensus meeting. The total mean time from Enköping, Västerås and Gävle were 6.48, 6.32 and 6.16 minutes respectively. The strength of agreement between the two assessors was substantial in Uppsala, Västerås and Gävle (ĸ 0.80, 0.79 and 0.76 respectively) and perfect in Enköping (ĸ 0.89). For the content validity were there no differences between the hospitals in the distribution of question U1-P10. Conclusion AT-HARM10 was for the first time used outside Uppsala and has been externally validated with data from the hospitals in Enköping, Västerås, and Gävle. The time needed per admission for the two assessors was low which confirms that it is possible to have final-year pharmacy students as assessors. This information is important both within the MedBridge trial and if the tool would be used in outer clinical studies.
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7

Iwakami, Naotsugu. "Optimal Sampling in Derivation Studies was Associated with Improved Discrimination in External Validation for Heart Failure Prognostic Models." Kyoto University, 2020. http://hdl.handle.net/2433/259731.

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8

Hage, Mhamad El. "Etude de la qualité géomorphologique de modèles numériques de terrain issus de l’imagerie spatiale." Thesis, Paris, CNAM, 2012. http://www.theses.fr/2012CNAM0846/document.

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La production de Modèles Numériques de Terrain (MNT) a subi d’importantes évolutions durant les deux dernières décennies en réponse à une demande croissante pour des besoins scientifiques et industriels. De nombreux satellites d’observation de la Terre, utilisant des capteurs tant optiques que radar, ont permis de produire des MNT couvrant la plupart de la surface terrestre. De plus, les algorithmes de traitement d’images et de nuages de points ont subi d’importants développements. Ces évolutions ont fourni des MNT à différentes échelles pour tout utilisateur. Les applications basées sur la géomorphologie ont profité de ces progrès. En effet, ces applications exploitent les formes du terrain dont le MNT constitue une donnée de base. Cette étude a pour objectif d’évaluer l’impact des paramètres de production de MNT par photogrammétrie et par InSAR sur la qualité de position et de forme de ces modèles. La qualité de position, évaluée par les producteurs de MNT, n’est pas suffisante pour évaluer la qualité des formes. Ainsi, nous avons décrit les méthodes d’évaluation de la qualité de position et de forme et la différence entre elles. Une méthode originale de validation interne, qui n’exige pas de données de référence, a été proposée. Ensuite, l’impact des paramètres de l’appariement stéréoscopique, du traitement interférométrique ainsi que du rééchantillonnage, sur l’altitude et les formes, a été évalué. Finalement, nous avons conclu sur des recommandations pour choisir correctement les paramètres de production, en particulier en photogrammétrie.Nous avons observé un impact négligeable de la plupart des paramètres sur l’altitude, à l’exception de ceux de l’InSAR. Par contre, un impact significatif existe sur les dérivées de l’altitude. L’impact des paramètres d’appariement présente une forte dépendance avec la morphologie du terrain et l’occupation du sol. Ainsi, le choix de ces paramètres doit être effectué en prenant en considération ces deux facteurs. L’effet des paramètres du traitement interférométrique se manifeste par des erreurs de déroulement de phase qui affectent principalement l’altitude et peu les dérivées. Les méthodes d’interpolation et la taille de maille présentent un impact faible sur l’altitude et important sur ses dérivées. En effet, leur valeur et leur qualité dépendent directement de la taille de maille. Le choix de cette taille doit s’effectuer selon les besoins de l’application visée. Enfin, nous avons conclu que ces paramètres sont interdépendants et peuvent avoir des effets similaires. Leur choix doit être effectué en prenant en considération à la fois l’application concernée, la morphologie du terrain et son occupation du sol afin de minimiser l’erreur des résultats finaux et des conclusions
The production of Digital Elevation Models (DEMs) has undergone significant evolution duringthe last two decades resulting from a growing demand for scientific as well as industrial purposes.Many Earth observation satellites, using optical and radar sensors, have enabled the production ofDEMs covering most of the Earth’s surface. The algorithms of image and point cloud processing havealso undergone significant evolution. This progress has provided DEMs on different scales, which canfulfill the requirements of many users. The applications based on geomorphology have benefitted fromthis evolution. Indeed, these applications concentrate specifically on landforms for which the DEMconstitutes a basic data.The aim of this study is to assess the impact of the parameters of DEM production byphotogrammetry and InSAR on position and shape quality. The position quality, assessed by DEMproducers, is not sufficient for the evaluation of shape quality. Thus, the evaluation methods ofposition and shape quality and the difference between them are described. A novel method of internalvalidation, which does not require reference data, is proposed. Then, the impact of image matchingand interferometric processing parameters as well as resampling, on elevation and shapes, is assessed.Finally, we conclude on recommendations on how to choose the production parameters correctly,particularly for photogrammetry.We observe little impact from most of the parameters on the elevation, except InSAR parameters.On the other hand, there is a significant impact on the elevation derivatives. The impact of matchingparameters presents a strong dependence on the terrain morphology and the landcover. Therefore,these parameters have to be selected by taking into account these two factors. The effect ofinterferometric processing manifests by phase unwrapping errors that mainly affect the elevation andless the derivatives. The interpolation methods and the mesh size present a small impact on theelevation and a significant impact on the derivatives. Indeed, the value of the derivatives and theirquality depend directly on the mesh size. The selection of this size has to be made according to theforeseen application. Finally, we conclude that these parameters are interdependent and can havesimilar effects. They must be selected according to the foreseen application, the terrain morphologyand the landcover in order to minimize the error in the final results and the conclusions
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Grün, Bettina, Paul Hofmarcher, Kurt Hornik, Christoph Leitner, and Stefan Pichler. "Deriving Consensus Ratings of the Big Three Rating Agencies." Incisive Financial Publishing, 2013. http://epub.wu.ac.at/4052/1/consensus_Rev3.pdf.

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This paper introduces a model framework for dynamic credit rating processes. Our framework aggregates ordinal rating information stemming from a variety of rating sources. The dynamic of the consensus rating captures systematic as well as idiosyncratic changes. In addition, our framework allows to validate the different rating sources by analyzing the mean/variance structure of the rating deviations. In an empirical study for the iTraxx Europe companies rated by the big three external rating agencies we use Bayesian techniques to estimate the consensus ratings for these companies. The advantages are illustrated by comparing our dynamic rating model to a naive benchmark model. (authors' abstract)
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Smith, Allison B. Smith. "Validation Of A Smartphone Application For Measuring Shoulder Internal Rotation and External Rotation Range Of Motion With Intra-Rater Reliability." Otterbein University / OhioLINK, 2016. http://rave.ohiolink.edu/etdc/view?acc_num=otbn1461840909.

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11

Brandes, Alina Christa Annemarie Verfasser], and Wolf [Akademischer Betreuer] [Rogowski. "External validation of decision-analytic models based on claims data of health insurance funds / Alina Christa Annemarie Brandes. Betreuer: Wolf Rogowski." München : Universitätsbibliothek der Ludwig-Maximilians-Universität, 2016. http://d-nb.info/1101343907/34.

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Ferreira, Ester Serrano. "Identificação dos fatores interferentes no transporte de concentrado de hemácias." Universidade de São Paulo, 2017. http://www.teses.usp.br/teses/disponiveis/17/17155/tde-07062017-150220/.

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Introdução. O transporte é um procedimento crítico na manutenção da cadeia do frio do sangue. Falhas neste procedimento podem comprometer a sua qualidade e a segurança transfusional. Objetivo. Avaliar as não conformidades (NC) do Hemocentro de Ribeirão Preto relacionadas ao transporte de concentrado de hemácias (CH). Analisar caixas térmicas e gelos recicláveis submetidos à temperatura de 20°C e 30°C e propor melhorias neste processo. Métodologia. Estudo retrospectivo de NC relacionadas ao transporte de CH no software do sistema da qualidade do Hemocentro de Ribeirão Preto e pesquisa experimental realizada com três caixas diferentes em combinação com três gelos recicláveis distintos, simulando uma situação de transporte, nas temperaturas externas de 20°C e 30°C. Realizou-se uma estatística descritiva com os dados. Utilizou-se a metodologia de análise de variância (ANOVA), com o auxílio do software SAS® 9, utilizando a PROC GLM. Para as comparações foram utilizados contrastes ortogonais baseados na distribuição t. Resultados. Os resultados mostraram diferenças significativas no desempenho entre as caixas e entre os gelos recicláveis. No entanto, as maiores diferenças ocorreram entre as temperaturas externas de 20°C e 30°C, indicando a interferência da temperatura externa na temperatura do conteúdo interno. Outra diferença encontrada foi entre pontos de aferição das temperaturas, dentro da mesma caixa, indicando que a distribuição do ar, no interior da caixa não é homogênea. Conclusão. São vários os interferentes existentes durante o transporte de CH, que podem comprometer a qualidade do sangue. O transporte deve ser validado, padronizando o maior número de variáveis possíveis, para minimizar as adversidades que ocorrem durante o procedimento
Introduction. The transport is a critical procedure in the maintenance of the blood cold chain. Failures in this procedure can compromise the blood quality and transfusion safety. Purpose: Evaluate the non-conformances (NC) of Hemocentro de Ribeirão Preto related to the Red Blood Cell (RBC) transport. Verify coolers, recycle ice at a temperature of 20°C and 30°C and propose improvements in this process. Methodology: Retrospective study of NC related to RBC transport in Hemocentro de Ribeirão Preto quality system software. Experimental research performed with three different insulated boxes combined with three different ice packs, simulating a situation of transport in the external temperatures of 20°C and 30°C. It was made a descriptive statistic of the data. The methodology of analysis of variance was used, through the software SAS® 9, using a PROC GLM. To do the comparisons orthogonal contrasts based on t distribution were used. Results: The results shown significant differences between insulated box and ice packs. However, the larger differences occurred between the temperatures of 20°C and 30°C, indicating that the external temperature interfere in the temperature inside the box. Another difference found was between points of temperature, inside the same insulated box, indicating that the air distribution inside the insulated box is not homogeneous. Conclusion. During RBC transport, many interfering exist that can compromise the blood quality. The transport must be validated, standardizing the largest number of details that is possible, to minimize adversity that occur during the procedure
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Ukah, Ugochinyere Vivian. "The fullPIERS risk prediction model for women with pre-eclampsia : external validation, recalibration and added value of a novel biomarker (placental growth factor)." Thesis, University of British Columbia, 2017. http://hdl.handle.net/2429/63394.

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The hypertensive disorders of pregnancy (HDPs), including pre-eclampsia, complicate up to 10% of pregnancies and are leading causes of maternal and perinatal morbidity and mortality. The fullPIERS model was developed to identify and quantify the risks of developing complications for women with pre-eclampsia in high-resource settings and to aid clinicians in managing such pregnancies. Prior to introducing the model into clinical practice, it is important to assess its external validity. Recalibration, if required, and addition of new biomarkers may be helpful to improve the predictive performance of the model. The objectives of this thesis were (i) to assess the external validity of the fullPIERS risk prediction model for women with pre-eclampsia (ii) recalibrate the model if necessary, and (iii) to assess the incremental value of adding the biomarker, placental growth factor (PlGF), to the model. Using abstracted medical records of women admitted into tertiary units in four high-income countries (HICs), the fullPIERS model was assessed for geographical and temporal validity. The model’s predictive ability in women with a broader spectrum of disease including early-onset pre-eclampsia, other HDPs and low and middle-income countries was also assessed using existing cohorts. Good performance was interpreted based on discrimination (AUROCs ≥0.7) and calibration (slope ≥ 0.7). Stratification and classification accuracy of the model were also assessed. The fullPIERS model showed good discriminatory performance on temporal and geographical validity (AUROCs >0.8) and also in broader HDPs (AUROCs >0.7). Medium to high likelihood ratios were estimated (>5 to >10) at a predicted probability cut-off of ≥30% for ruling in adverse maternal outcomes. Calibration was reduced in all cohorts (<0.7), except in the temporal validation, suggesting a need for recalibration. Recalibration of the model improved the calibration performance but did not improve the discriminatory and stratification of the model. There was little incremental value of adding PlGF to the model. The fullPIERS model has been successfully validated externally and can be implemented into routine clinical care in similar settings to inform clinical decisions. This will aid in appropriate allocation of care and resources to the patients, and contributing in reducing maternal morbidity and mortality resulting from pre-eclampsia.
Medicine, Faculty of
Obstetrics and Gynaecology, Department of
Graduate
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Sharf, Allyson J. "External Validation of the MMPI-A-RF with Youth with Mental Health Needs: A Systematic Examination of Symptom-Based Correlates and Interpretive Statements." Thesis, University of North Texas, 2019. https://digital.library.unt.edu/ark:/67531/metadc1538766/.

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Over the last several decades, the Minnesota Multiphasic Personality Inventory - Adolescent (MMPI-A) has remained one of the most extensively studied and commonly used adolescent assessment measures. Most recently, the MMPI-A was revised, published as the Minnesota Multiphasic Personality Inventory - Adolescent Restructured Form (MMPI-A-RF). Given the infancy of the extant MMPI-A-RF literature, the current dissertation sought to be one of the first criterion studies since the test manual to establish its relevant clinical correlates in a sample of youth referred for mental health services. Following in line with previous clinical correlate research, the psychometric properties of the MMPI-A-RF were determined. Under this approach, the present study bolstered support for the construct validity of the RC scales through the identification of clinically relevant, scale and item-level correlates. In particular, the RCd and RC4 evidenced especially strong convergent and discriminant validity. As a result, the current study highlighted the MMPI-A-RF's efficacy in detecting psychopathology along the broad externalizing and internalizing spectrum. In addition, the role of gender and its effect on MMPI-A-RF clinical interpretations were explored. Practical recommendations for ensuring a gender-specific approach to MMPI-A-RF interpretation were outlined.
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Armon, Ruby. "A prospective evaluation of the community assessment tools (CATs) in children and adults with acute lower respiratory tract infections : an external validation study." Thesis, University of Nottingham, 2017. http://eprints.nottingham.ac.uk/45134/.

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Background: CATs is a hospital admission triage tool for influenza and pneumonia, and comprises of 7 criteria (6 objective and 1 subjective); any one of which is expected to trigger hospital admission in adults and children. As the CATs was only recently developed, its performance has only been assessed in the United Kingdom using data from the 2009 A (H1N1) flu pandemic. An external validation study is thus required to assess the generalisability of the CATs in a new patient population before it is recommended for adoption in practice. Aim: The primary aim of this thesis was to prospectively evaluate the predictive performance of the Community Assessment Tools across a range of acute lower respiratory tract infections in a new geographical setting. Five studies were included in this thesis, each addressing a specific objective in order to achieve the primary aim of this research: • The first study examined the predictive performance of individual CATs criteria with regard to the need for hospital based care and mortality, • The second study examined the performance of CATs as unweighted and weighted scoring indexes for assessing these outcomes in adults and children with ALRTI, • The third study compared the performance of the unweighted CATs scoring index and the well-established pneumonia severity score –CRB65 in two separate sensitivity analyses involving cases of suspected ALRTI and pneumonia in adults. • The fourth study sought to investigate the value of clinical intuition in medical decision-making by comparing the performance of the CATs as an unweighted scoring index with or without the inclusion of its subjective criterion (causing other clinical concern). • The fifth study was a qualitative exploration of critical care practices in Nigerian hospitals, conducted to provide contextual interpretation of findings related to the performance of the CATs in predicting the need for critical care and mechanical ventilation. Methods: Data specific to the CATs and CRB65 were recorded at the initial consultation of patients with symptoms suggestive of an acute lower respiratory tract infection. The performance of the tools with regard to predicting the need for hospital admission , acute care interventions (supplemental oxygen, IV antibiotics and IV fluids), or any deaths on admission were assessed using specificity, sensitivity, negative and positive predictive values, Area under Receiver Operating Characteristic Curves (AUROC) with 95% confidence intervals and Hosmer-Lemeshow goodness-of-fit test. The qualitative study was conducted within a pragmatic paradigm and a semi-structured guide was used to for individual interviews with key hospital staff. Thematic analysis was used for analysing interview data. Results: Data were obtained for 1016 (809 children < 16years) consecutive patients from four hospitals in Lagos Nigeria. In the univariate analysis each CATs criterion significantly predicted an outcome which indicated the need for hospital care or mortality, also none of these criteria were redundant in the multivariable analysis. Criterion C representing low oxygen saturation levels of 92% or less and Criterion G –clinicians’ intuition or gut feelings ,were the best predictors of the need for hospital based care and risk of death in both children and adults. The predictive accuracy of the individual criteria was generally low in terms of AUROC values, but this improved when they were combined to create scoring indexes. An unweighted CATs threshold score of three points or more was appropriate for identifying both adults and children who would potentially benefit from hospital based care and therapeutic interventions. In the comparison between CRB65 and the unweighted CATs score, the latter was seen to have better discrimination and calibration qualities for predicting all outcomes in adults with ALRTI, and although both the unweighted CATs and CRB65 scores demonstrated good predictive ability for the outcome ‘in-hospital mortality’ in adults with pneumonia, the unweighted CATs score outperformed the CRB65 in terms of AUROC values, however, the difference was marginal and statistically insignificant. This thesis provided evidence to support considering clinical intuition or gut feelings in the assessment of patients with ALRTI, as the predictive performance of the unweighted CATs score was significantly better with the inclusion of subjective criterion G (causing other clinical concern) than when this criterion was omitted. Due to insufficient data it was not possible to assess the performance of the CATs in regard to the outcome ‘need for critical care’. Findings from the qualitative study revealed that ALRTI was not a common indication for ICU admission in these hospitals, also that clinical predictions tools were not generally used in this regard, rather decisions regarding ICU admissions were determined by the ability to pay and bed availability. Conclusion: the CATs criteria showed geographical generalisability despite differences in case-mix and geographical variations. When combined to create an unweighted scoring system, CATs showed good potential for guiding decisions to admit adults and children with ALRTI to hospital for further care. Although CATs was developed for use during an influenza pandemic, the unweighted CATs score could be a useful tool for guiding admission decisions in adults with interpandemic pneumonia, as it performed reasonably well when compared with a widely validated and established pneumonia severity score.
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Sanhokwe, Marcia. "Determination and validation of medicinal plants used by farmers to control internal and external parasites in goats in the Eastern Cape Province, South Africa." Thesis, University of Fort Hare, 2015. http://hdl.handle.net/10353/2249.

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The broad objective of the study was to determine and validate medicinal plants used by resource-limited farmers to control internal and external parasites in goats in the Eastern Cape Province, South Africa. A survey was conducted among 50 farmers and three herbalists to determine medicinal plants used to control parasites in goats. The survey revealed nine plant species belonging to eight families that were used. Among the identified plant species, Aloe ferox, Acokanthera oppositifolia and Elephantorrhiza elephantina were the plants having the highest Fidelity Level for their use, each scored 100.00 percent, followed by Albuca setosa (83.33 percent). These plants were then selected for validation studies. Gas-Chromatography-Mass-Spectrometry (GC-MS) revealed 7, 33, 26 and 32 bioactive phytochemicals in A. ferox, E. elephantina, A. oppositifolia and A. setosa, respectively. Terpenes and fatty acids were present, oxygenated terpenes being the most abundant hydrocarbons present in all the four plant species. The effect of acetone, methanol and ethanol extracts of leaves of Aloe ferox and Acokanthera oppositifolia on tick repellency and acaricidal activity were investigated on blood engorged Ambylomma hebraeum and Rhipicephalus decoloratus ticks at concentration 15, 30 and 50 percent. The 30 and 50 percent acetone extract of A. ferox and Dazzel dip had the highest acaricidal properties of 100 percent. The 50 percent methanol extract of A. oppositifolia and 50 percent acetone extract of A. ferox had the highest repellency activity of 89 percent and 85.33 percent, respectively. Results from this study revealed that the efficacy of medicinal plants used by farmers to control ticks vary with the type of solvent used for extracting the bioactive compounds. Furthermore, it revealed that Aloe ferox and A. opppositifolia plant extracts possess repellent and acaricidal activities. In a study to investigate the anthelminthic effect of crude extracts of Elephantorrhiza elephantina and Albuca setosa plants, significant anthelminthic effect on nematodes was observed in both plants. In this study, all E. elephantina and A. setosa extracts caused paralysis and mortality. Methanol was the most effective solvent in extracting bioactive compounds and methanol extract showed the best anthelminthic effects among the crude extracts investigated in both plants. The least time taken for the worms to be paralysed was 8.33 mins and 14.33mins in 100mg/ml methanol extracts of E. elephantina and A. setosa, resepectively. Methanol extract of E. elephantina and A. setosa (100mg/ml) had the highest anthelminthic activity and mortality was recorded after 18mins and 20mins, respectively. Results from this study revealed that these two plants possess anthelminthic activities. The study revealed that resource-limited farmers use medicinal plants to control internal and external parasites in goats. Gas-Chromatography-Mass-Spectrometry analysis showed that these plants contain bioactive compounds that have a potential in controlling parasites. Validation studies showed that A. ferox and A. oppositifolia possess repellent and acaricidal activities whereas A. setosa and E. elephantina possess anthelminthic activities.
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Grün, Bettina, Paul Hofmarcher, Kurt Hornik, Christoph Leitner, and Stefan Pichler. "Deriving Consensus Ratings of the Big Three Rating Agencies." Institute for Statistics and Mathematics, WU Vienna University of Economics and Business, 2010. http://epub.wu.ac.at/728/1/document.pdf.

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This paper introduces a model framework for dynamic credit rating processes. Our framework aggregates ordinal rating information stemming from a variety of rating sources. The dynamic of the consensus rating captures systematic as well as idiosyncratic changes. In addition, our framework allows to validate the different rating sources by analyzing the mean/variance structure of the rating errors. In an empirical study for the iTraxx Europe companies rated by the big three external rating agencies we use Bayesian techniques to estimate the consensus ratings for these companies. The advantages are illustrated by comparing our dynamic rating model to a benchmark model. (author´s abstract)
Series: Research Report Series / Department of Statistics and Mathematics
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Madine, George. "Psychological Health in Companies. An investigation into the relationships between work characteristics, job roles and psychological health in companies." Thesis, University of Bradford, 2009. http://hdl.handle.net/10454/4287.

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The research literature contains a significant amount of information on the psychological health of managers, however, relatively little has been written about the psychological health of workers. There has been a long held assumption that there is little difference in the psychological health of workers and managers. This study challenges that assumption and investigates differences in psychological health that appertain to job role and job characteristics determined by job role. This study tested two related hypotheses, firstly, that 'managers have significantly better psychological health than workers'; secondly, that 'that better psychological health was largely due to the increased self esteem that comes from having a more socially desirable role'. Initial analyses of the data indicated that hypothesis 1 was upheld, but when split by sex hypothesis 1 was only upheld for females and not males; similarly hypothesis 2 was only upheld for females. This result was attributed to the influence of two variables, the 'attribution of blame' and 'need for external validation', and the different moderator and mediator roles they play for males and females. The study contradicts the assertion that the psychological health of workers and managers is similar, if not the same, and uses the differences found to explain why research in this field has often produced conflicting results. Areas of potential future research are indicated.
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Machrafi, Hatim. "Développement et validation expérimentale de schémas cinétiques pour des mélanges d'hydrocarbures pour une combustion HCCI : étude du processus d'auto-inflammation et application au moteur à combustion interne." Paris 6, 2007. http://www.theses.fr/2007PA066040.

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Une des solutions très prometteuses pour la réduction des émissions polluantes et de la consommation des moteurs à combustion interne est la mise en place de combustions alternatives pour une optimisation à la source. En particulier, de nombreuses études sont menées autour du développement d’une combustion en charge homogène par auto inflammation appelée « Homogeneous Charged Compression Ignition ». Cependant, le contrôle de ce mode de combustion nécessite une recherche avancée incluant une approche interdisciplinaire associant la chimie, la mécanique des fluides et les contraintes d’un fonctionnement moteur. Cette thèse a pour objet l’étude de l’auto inflammation en mode homogène traité d’un point de vue numérique et expérimental. L'étude numérique s’intéresse au développement de mécanismes réduits de carburants de référence. Ces mécanismes réduits sont introduits dans le cadre de modèles plus généraux simulant un fonctionnement de cycle moteur, se focalisant sur trois carburants de référence ; le n-heptane, l'isooctane et le toluène. Trois mécanismes et un mécanisme « mélange » sont ainsi proposés et font l’objet tout d’abord d’une validation numérique et ensuite d’une validation expérimentale. Le mécanisme final « mélange » est composé de 62 réactions et de 49 espèces. En outre, l'interaction des oxydes d’azote NO avec les hydrocarbures est incluse par un appendice cinétique. La validation expérimentale est effectuée dans une gamme de paramètres respectant les conditions de fonctionnement d’un mode HCCI. Les gammes de température d'admission sont comprise entre 35 et 70 °C, avec une richesse entre 0,28 et 0,64 et des taux de compression entre 7 et 14, et ceci pour différentes teneurs des 3 composées de base formant le carburant. En particulier, les carburants testés présentent une gamme complète de proportion de n-heptane/iso-octane. En ce qui concerne le cas des mélanges de n-heptane/toluène, la valeur maximum étudiée du pourcentage volumique de toluène est de 40 %. Des analyses comparatives entre l'essence, le gasoil et leurs substituts de référence sont proposées. En outre, l'effet de NO sur le processus d'auto-inflammation est étudié jusqu'à une addition de 170 ppm. Une étude complète des effets de l’introduction d’EGR est présentée avec en particulier les effets de la dilution par N2 et CO2, les effets du niveau thermiques sur une gamme de 30 à 120 °C, et les effets chimiques de certaines espèces comme le CO, le CH2O et de CH3CHO. L'analyse expérimentale a été soutenue par le mécanisme validé. De cette analyse aboutit un ensemble de conclusions en ce qui concerne le contrôle du processus d'auto-inflammation en mode HCCI.
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Caron, Jérôme. "Etude et validation clinique d'un modèle aux moments entropique pour le transport de particules énergétiques : application aux faisceaux d'électrons pour la radiothérapie externe." Thesis, Bordeaux, 2016. http://www.theses.fr/2016BORD0452/document.

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En radiothérapie externe, les simulations des dépôts de dose aux patients sont réalisées sur des systèmesde planification de traitement (SPT) dotés d'algorithmes de calcul qui diffèrent dans leur modélisationdes processus physiques d'interaction des électrons et des photons. Or ces SPT, bien que rapides enclinique, montrent parfois des erreurs significatives aux abords des hétérogénéités du corps humain. Montravail de thèse a consisté à valider le modèle aux moments entropique M1 pour des faisceaux d'électronscliniques. Cet algorithme développé au CELIA dans le cadre de la physique des plasmas repose sur larésolution de l'équation cinétique de transport de Boltzmann linéarisée selon une décomposition auxmoments. M1 nécessite une fermeture du système d'équations basée sur le H-Théorème (maximisationde l'entropie). Les cartographies de dose 1D de faisceaux d'électrons de 9 et 20 MeV issues de M1 ontété comparées à celles issues de codes de référence : macro Monte-Carlo clinique (eMC) et full Monte-Carlo (GEANT-MCNPX) ainsi qu'à des données expérimentales. Les cas tests consistent en des fantômesd'abord homogènes puis de complexité croissante avec insertion d'hétérogéenéités mimant les tissus osseuxet pulmonaire. In fine, le modèle aux moments M1 démontre des propriétés de précision meilleures quecertains algorithmes de type Pencil Beam Kernel encore utilisés cliniquement et proches de celles fourniespar des codes full Monte-Carlo académiques ou macro Monte-Carlo cliniques, même dans les cas testscomplexes retenus. Les performances liées aux temps de calcul de M1 ont été évaluées comme étantmeilleures que celles de codes Monte-Carlo
In radiotherapy field, dose deposition simulations in patients are performed on Treatment Planning Systems (TPS) equipped with specific algorithms that differ in the way they model the physical interaction processes of electrons and photons. Although those clinical TPS are fast, they show significant discrepancies in the neighbooring of inhomogeneous tissues. My work consisted in validating for clinical electron beams an entropic moments based algorithm called M1. Develelopped in CELIA for warm and dense plasma simulations, M1 relies on the the resolution of the linearized Boltzmann kinetic equation for particles transport according to a moments decomposition. M1 equations system requires a closure based on H-Theorem (entropy maximisation). M1 dose deposition maps of 9 and 20 MeV electron beams simulations were compared to those extracted from reference codes simulations : clinical macro Monte-Carlo (eMC) and full Monte-carlo (GEANT4-MCNPX) codes and from experimental data as well. The different test cases consisted in homogeneous et complex inhomogeneous fantoms with bone and lung inserts. We found that M1 model provided a dose deposition accuracy better than some Pencil Beam Kernel algorithm and close of those furnished by clinical macro and academic full Monte-carlo codes, even in the worst inhomogeneous cases. Time calculation performances were also investigated and found better than the Monte-Carlo codes
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Winter, Audrey. "Modèles d'appariement du greffon à son hôte, gestion de file d'attente et évaluation du bénéfice de survie en transplantation hépatique à partir de la base nationale de l'Agence de la Biomédecine." Thesis, Montpellier, 2017. http://www.theses.fr/2017MONTS024/document.

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La transplantation hépatique (TH) est la seule intervention possible en cas de défaillance hépatique terminale. Une des limitations majeures à la TH est la pénurie d'organes. Pour pallier ce problème, les critères de sélection des donneurs ont été élargis avec l'utilisation de foie de donneurs dits à "critères étendus" (extended criteria donor (ECD)). Cependant, il n'existe pas de définition univoque de ces foies ECD. Un score donneur américain a donc été mis en place : le Donor Risk Index (DRI), pour qualifier ces greffons. Mais à qui doit-on donner ces greffons "limites"? En effet, une utilisation appropriée des greffons ECD pourrait réduire la pénurie d'organes. Le but de cette thèse est d'établir un nouveau système d'allocation des greffons qui permettrait à chaque greffon d'être transplanté au candidat dont la transplantation permettra le plus grand bénéfice de survie et d'évaluer l'appariement entre donneurs et receveurs en tenant compte des greffons ECD.La première étape a consisté à effectuer une validation externe du DRI ainsi que du score qui en découle : l'Eurotransplant-DRI. Toutefois la calibration et la discrimination n'étaient pas maintenus dans la base française. Un nouveau score pronostique donneur a donc été élaboré : le DRI-Optimatch, à l'aide d'un modèle de Cox donneur ajusté sur les covariables receveur. Le modèle a été validé par bootstrap avec correction de la performance par l'optimisme.La seconde étape consista à explorer l'appariement entre donneur et receveur afin d'attribuer les greffons ECD de manière optimale. Il a été tenu compte des critères donneurs et receveurs, tels qu'évalués par le DRI-Optimatch et par le MELD (Model for End-stage Liver Disease, score pronostique receveur), respectivement. La méthode de stratification séquentielle retenue s'inspire du principe de l'essai contrôlé randomisé. Nous avons alors estimé, à l'aide de rapport de risques, quel bénéfice de survie un patient donné (repéré à l'aide du MELD) pourrait avoir avec un greffon donné (repéré à l'aide du DRI-Optimatch) en le comparant avec le groupe de référence composé des patients (même MELD), éligibles à la greffe, restés sur liste dans l'attente d'un meilleur greffon (DRI-Optimatch plus petit).Dans une troisième étape, nous avons développé un système d'allocation basé sur le bénéfice de survie alliant deux grands principes dans l'allocation de greffons; l'urgence et l'utilité. Dans ce type de système, un greffon alloué est attribué au patient avec la plus grande différence entre la durée de vie post-transplantation prédite et la durée estimée sur la liste d'attente pour un donneur spécifique. Ce modèle est principalement basé sur deux modèles de Cox : un pré-greffe et un post-greffe. Dans ces deux modèles l'évènement d'intérêt étant le décès du patient, pour le modèle pré-greffe, la censure dépendante a été prise en compte. En effet, sur liste d'attente le décès est bien souvent censuré par un autre évènement : la transplantation. Une méthode dérivée de l'Inverse Probability of Censoring Weighting a été utilisée pour pondérer chaque observation. De plus, données longitudinales et données de survie ont aussi été utilisées. Un modèle "en partie conditionnel", permettant d'estimer l'effet de covariables dépendantes du temps en présence de censure dépendante, a été utilisé pour modéliser la survie pré-greffe.Après avoir développé un nouveau système d'allocation, la quatrième et dernière étape, nous a permis de l'évaluer à travers de simulation d'évènement discret ou DES : Discret Event Simulation
Liver transplantation (LT) is the only life-saving procedure for liver failure. One of the major impediments to LT is the shortage of organs. To decrease organ shortage, donor selection criteria were expanded with the use of extended criteria donor (ECD). However, an unequivocal definition of these ECD livers was not available. To address this issue, an American Donor Risk Index (DRI) was developed to qualify those grafts. But to whom should those ECD grafts be given? Indeed, a proper use of ECD grafts could reduce organ shortage. The aim of this thesis is to establish a new graft allocation system which would allow each graft to be transplanted in the candidate whose LT will allow the greatest survival benefit; and to evaluate the matching between donors and recipients taking into account ECD grafts.The first step was the external validation of the DRI as well as the resultant Eurotransplant-DRI score. However, calibration and discrimination were not maintained on the French database. A new prognostic donor score: the DRI-Optimatch was then developed using a Cox donor model with adjustment on recipient covariates. The model was validated by bootstrapping with correction of the performance by the optimism.The second step was to explore the matching between donors and recipients in order to allocate ECD grafts optimally. Consideration should be given to the donor and recipient criteria, as assessed by the DRI-Optimatch and the Model for End-stage Liver Disease (MELD), respectively. The sequential stratification method retained is based on the randomized controlled trial principle. We then estimated, through hazard ratios, the survival benefit for different categories of MELD and DRI-Optimatch compared against the group of candidates remaining on the wait list (WL) and waiting for a transplant with a graft of better quality (lower DRI-Optimatch).In the third step, we have developed an allocation system based on survival benefit combining the two main principles in graft allocation; urgency and utility. In this system, a graft is allocated to the patient with the greatest difference between the predicted post-transplant life and the estimated waiting time for a specific donor. This model is mainly based on two Cox models: pre-LT and post-LT. In these two models the event of interest being the death of the patient, for the pre-graft model, the dependent censoring was taken into account. Indeed, on the WL, death is often censored by another event: transplantation. A method derived from Inverse Probability of Censoring Weighting was used to weight each observation. In addition, longitudinal data and survival data were also used. A partly conditional model, to estimate the effect of time-dependent covariates in the presence of dependent censoring, was therefore used for the pre-LT model.After developing a new allocation system, the fourth and final step was to evaluate it through Discrete Event Simulation (DES)
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22

Zambon, Azevedo Vittoria. "Mise au point d’un nouvel outil diagnostique de l’obésité sarcopénique : relations avec la dysfonction du tissu adipeux, l’insulinorésistance et la sévérité de l’atteinte hépatique." Electronic Thesis or Diss., Sorbonne université, 2024. https://accesdistant.sorbonne-universite.fr/login?url=https://theses-intra.sorbonne-universite.fr/2024SORUS170.pdf.

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L'obésité sarcopénique (OS) est une condition caractérisée par la coexistence de l'obésité et de la sarcopénie, c'est-à-dire une réduction de la masse et de la fonction musculaires. Diagnostiquer l'OS est très complexe en raison de l'absence de critères diagnostiques universellement acceptés, ce qui entraîne des diagnostics imprécis et une estimation hautement variable de sa prévalence. Face à ces limitations, l'objectif de cette thèse était de développer un outil de diagnostic empirique pour l'OS aidé d'intelligence artificielle, basé sur l'analyse de la composition corporelle. Nous avons élaboré l'AIM-SO score dans une population de sujets en surpoids/obésité puis nous l'avons testé dans deux autres populations, l'une de patients avec obésité sévère subissant une chirurgie bariatrique, l'autre dans la population générale de l'UK Biobank. Une étude longitudinale a également été menée, avec un suivi à un an chez les sujets ayant subi une chirurgie bariatrique. Nous avons étudié les corrélations cliniques, en particulier cardiométaboliques et hépatiques, notamment histologiques per-opératoires, dans la cohorte bariatrique. La prévalence d'OS a été très proche entre ces trois cohortes. L'OS diagnostiquée par l'AIM-SO score était associée à de multiples comorbidités cardiométaboliques, ainsi qu'à une forme plus sévère d'atteinte inflammatoire et fibrosante du foie. Malgré la perte de poids, le bénéfice métabolique (rémission des comorbidités) après chirurgie bariatrique était moindre chez les patients ayant une OS. Des analyses préliminaires de la cohorte UK Biobank ont montré une association significative entre l'OS diagnostiquée par l'AIM-SO score et des paramètres de fonctionnalité musculaire, en particulier la force musculaire. Nous proposons ce nouvel outil diagnostique pour standardiser le diagnostic d'OS et identifier des patients en situation d'obésité avec sarcopénie dont le phénotype cardiométabolique et hépatique est plus sévère. Le diagnostic d'OS pourrait également renseigner le bénéfice attendu des différentes interventions à visée de réduction pondérale participant ainsi à une prise en charge médicale personnalisée
Sarcopenic obesity (SO) is a condition characterized by the coexistence of obesity and sarcopenia, the latter defined as a reduction in muscle mass and function. Diagnosing SO is highly complex due to the lack of universally accepted diagnostic criteria, leading to imprecise diagnoses and highly variable prevalence estimates. Given this scenario, this thesis aimed to develop an empirical diagnostic tool for SO using artificial intelligence, based on the analysis of body composition. We developed the AIM-SO score in a population of patients with overweight/obesity and tested it in two other populations: patients with severe obesity undergoing bariatric surgery (BS) and the general population of the UK Biobank. A longitudinal study with a one-year follow-up was conducted in subjects who underwent BS. We examined clinical correlations, particularly cardiometabolic and hepatic, including perioperative histological findings in the bariatric cohort. The prevalence of SO was similar across these three cohorts. SO diagnosed by the AIM-SO score was associated with multiple cardiometabolic comorbidities and more severe inflammatory and fibrosing liver damage. Despite weight loss, the metabolic benefit (remission of comorbidities) after BS was lower in patients with SO. Preliminary analyses of the UK Biobank cohort showed a significant association between SO diagnosed by the AIM-SO score and parameters of muscular functionality, particularly muscle strength. We propose this new diagnostic tool to standardize the SO diagnosis and identify patients with obesity and sarcopenia who exhibit more severe cardiometabolic and hepatic phenotype. Diagnosing SO could also inform the expected benefit of various weight loss interventions, thus contributing to personalized medical management
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23

Karlsson, Kristin E. "Benefits of Pharmacometric Model-Based Design and Analysis of Clinical Trials." Doctoral thesis, Uppsala universitet, Institutionen för farmaceutisk biovetenskap, 2010. http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-133104.

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Quantitative pharmacokinetic-pharmacodynamic and disease progression models are the core of the science of pharmacometrics which has been identified as one of the strategies that can make drug development more effective. To adequately develop and utilize these models one needs to carefully consider the nature of the data, choice of appropriate estimation methods, model evaluation strategies, and, most importantly, the intended use of the model. The general aim of this thesis was to investigate how the use of pharmacometric models can improve the design and analysis of clinical trials within drug development. The development of pharmacometric models for clinical assessment scales in stroke and graded severity events, in this thesis, show the benefit of describing data as close to its true nature as possible, as it increases the predictive abilities and allows for mechanistic interpretations of the models. Performance of three estimation methods implemented in the mixed-effects modeling software NONMEM; 1) Laplace, 2) SAEM, and 3) Importance sampling, applied when modeling repeated time-to-event data, was investigated. The two latter methods are to be preferred if less than approximately half of the individuals experience events. In addition, predictive performance of two validation procedures, internal and external validation, was explored, with internal validation being preferred in most cases. Model-based analysis was compared to conventional methods by the use of clinical trial simulations and the power to detect a drug effect was improved with a pharmacometric design and analysis. Throughout this thesis several examples have shown the possibility of significantly reducing sample sizes in clinical trials with a pharmacometric model-based analysis. This approach will reduce time and costs spent in the development of new drug therapies, but foremost reduce the number of healthy volunteers and patients exposed to experimental drugs.
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24

Brand-Labuschagne, Lelani. "Development and validation of new scales for psychological fitness and work characteristics of blue collar workers / Lelani Brand-Labuschagne." Thesis, North-West University, 2010. http://hdl.handle.net/10394/4429.

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Over the last decade the focus has shifted to ensure a holistic view of employee well-being in organisations by focusing on both physical and psychological well-being. Previous research suggests that work characteristics and psychological work-related well-being influence both the individual (i.e. health) and organisational outcomes (i.e. commitment, safety, productivity, etc.). Moreover, the increasing importance of focusing on work-related psychological well-being of employees is evident in legislation from around the world. In South Africa the Occupational Health and Safety legislation, spesifically the Construction Regulations, also recognises the importance of the psychological well-being of employees and refers to it as ?psychological fitness?. However, no clear definition or instrument for psychological fitness exists. Similarly, no instrument exist to measure work characteristics of blue-collar workers. The objectives of this research were 1) to propose a defintion for psychological fitness of blue-collar employees 2) to propose a theoretical framework to better our understanding of psychological fitness 3) to develop a psychological fitness instrument for blue-collar employees that is suitable for the South African context 4) to test the psychometric properties of the newly developed psychological fitness instrument 5) to develop a work characteristics questionnaire for blue-collar mine workers to gain insight into their work experiences, and 6) to evaluate the psychometric properties of the newly developed job demands-resources scale for blue-collar mine workers. The empirical study consisted of two phases. During the first phase, following an extensive literature review, a definition and theoretical framework for psychological fitness was proposed. Thereafter, a new instrument for measuring psychological fitness was developed and tested. An instrument for measuring the work characteristics of blue-collar mine workers has also been developed to further the understanding of their work experiences. During the second phase, the psychometric properties of the newly developed psychological fitness instrument were tested (i.e. factorial validity, factorial invariance, reliability and external validity; N = 2769). Furthermore, the psychometric properties of the newly developed job demands-resources scale for blue collar workers were also investigated (i.e. factorial validity, reliability and the relationship with theoretically relevant external variables; N = 361). During the conceptualisation process, the definition of psychological fitness has been proposed based on previous work-related well-being literature. The work-related well-being concepts, distress and eustress were proposed as indicators of psychological fitness. Therefore, psychological fitness was defined as a state in which an employee display high levels of emotional and mental energy and high levels of psychological motivation to be able to work and act safely. The dimensions of burnout and engagement were proposed as possible indicators of psychological fitness and included exhaustion, mental distance, cognitive weariness, vitality and work devotion. Furthermore, the underlying work-related well-being theories and models were identified as the theoretic framework to enable the development of a questionnaire for psychological fitness. In order to ensure that the low literacy employees understand the meaning of each questionnaire close attention has been paid during the development of items. Firstly, the psychological fitness instrument (SAPFI) for blue-collar employees has been translated into all the official languages of South Africa following a multistage translation process. Secondly, the job demands-resources scale for blue collar mine workers (JDRSM) has been translated into the three most commonly spoken languages (Sesotho, isiXhosa and Setswana) by employees working in this specific mine. During this phase various problematic items were identified and eliminated from both questionnaires using the Rasch measurement model. The final phase included the validation study where the psychometric properties of both the new instruments were investigated. The SAPFI results provided evidence for factorial validity, factorial invariance, reliability and significant relations with external variables of the distress scale. Although evidence was provided for the factorial validity, reliability and external validity of the eustress scale, factorial invariance could not be confirmed. Furthermore, the JDRSM results provided evidence for the factorial validity, reliability (except for the workload scale) and external validity. Recommendations for future research were made.
Thesis (Ph.D. (Industrial Psychology))--North-West University, Potchefstroom Campus, 2011.
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AGAZZI, Alessandro. "Positive Displacement Pumps: Pressure Modelling for Performance Analysis." Doctoral thesis, Università degli studi di Ferrara, 2016. http://hdl.handle.net/11392/2403254.

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La distribuzione della pressione all'interno di pompe volumetriche rotative varia periodicamente con la posizione del rotore; le conseguenti forze di pressione variabili rappresentano le principali fonti di vibrazioni e rumore. Questa tesi presenta diverse metodologie di modellazione per la simulazione dell'evoluzione di pressione in funzione della posizione del rotore in condizioni di lavoro, per questo tipo di pompe. Da un lato, viene sviluppato un approccio a parametri concentrati, applicato ad una pompa ad ingranaggi esterni per applicazioni automobilistiche; d’altro lato, viene studiato un approccio empirico, adottato nel caso di una famiglia di pompe a palette a cilindrata variabile. Nel primo approccio, il volume fluido della pompa è suddiviso in volumi di controllo e viene risolto un sistema di equazioni di continuità. La metodologia di modellazione è generale e può essere applicata a qualsiasi pompa ad ingranaggi a denti diritti con profilo ad evolvente. I vari coefficienti di efflusso in regime laminare o turbolento sono stimati mediante opportune simulazioni fluidodinamiche CFD. Il modello è stato soddisfacentemente validato mediante il confronto con risultati sperimentali, in termini di efficienza volumetrica e di ripple di pressione in mandata, in differenti condizioni operative. Il modello validato ha poi permesso di svolgere un’indagine di sensibilità, utile per l’ottimizzazione di parametri progettuali e funzionali della pompa: profondità e larghezza della ”Epsilon Groove”, eccentricità delle ruote nel corpo pompa, caratteristiche e temperatura dell’olio. . I risultati di questa analisi saranno utili nell’ottimizzazione dell’efficienza e del comportamento dinamico. Venendo all'approccio empirico, la modellazione della distribuzione di pressione non si basa in questo caso su leggi fisiche, ma sulla parametrizzazione di dati sperimentali: vengono individuate regole di correlazione tra le caratteristiche dell’evoluzione di pressione e i parametri geometrici e funzionali, relativamente ad una specifica famiglia di pompe di diverse dimensioni. Come applicazione del modello empirico, è stata condotta un'analisi del regime di usura e lubrificazione nel contatto tra le palette e l'anello statorico; tale analisi è stata effettuata mediante un metodo originale basato sul modello di usura di Archard, che associa il coefficiente di usura alle forze di contatto ottenute mediante il modello empirico, al tasso di usura ed alla durezza del materiale, misurati sperimentalmente; i risultati ottenuti vengono confrontati con i risultati forniti da un modello di lubrificazione elasto-idrodinamica al fine di valutare lo spessore del meato ed il regime di lubrificazione. Questo metodo è applicato ad un caso industriale al fine di dare indicazioni per la scelta appropriata dei materiali. Come risultato generale, entrambi gli approcci di modellizzazione producono risultati affidabili, utili per l'analisi delle eccitazioni vibro-acustiche, per l'ottimizzazione strutturale, nonché per la valutazione del regime di lubrificazione ed usura. Tuttavia si rileva che, da un lato, l'approccio a parametri concentrati permette di simulare il comportamento di pompe di diversa tipologia e di valutare l’effetto di una vasta gamma di modifiche, da prendere in considerare per l’ottimizzazione del progetto. D'altro lato, i modelli empirici sono meno flessibili rispetto ai modelli a parametri concentrati, in quanto sono applicabili solo a una famiglia di pompe; tuttavia, essi rappresentano strumenti efficaci per la R&S in ambito industriale, in quanto sono caratterizzati da tempi di sviluppo più rapidi e da un più facile impiego.
The pressure distribution inside rotary positive displacement pumps periodically varies with rotor position; the consequent variable pressure forces represent the main sources of casing vibration and noise emission. This dissertation presents different modelling methodologies for the simulation of pressure evolution in this kind of pumps, as a function of rotor position in working conditions: a lumped parameter approach is developed and applied to an external gear pump for automotive applications, while an empirical approach is studied and adopted in the case of a family of variable displacement vane pumps. In the former approach, the fluid volume of the pump is divided in several control volumes and a system of continuity equations is solved. This modelling methodology is general and can be applied to any spur gear pump with involute profile. The flow discharge coefficients in laminar or turbulent regime are estimated by appropriate CFD simulations. The validation of the model has been satisfactorily carried out for comparison with experimental results in term of volumetric efficiency and outlet pressure ripple, in different operating conditions. Through the validated model, a sensitivity analysis has been carried out, useful for optimizing some design and operating parameters of the pump: depth and width of the "Epsilon Groove", gear eccentricity with respect to the pump casing, oil temperature and properties. The results of this analysis will be useful for the optimization of the efficiency and the dynamic behaviour. On the other hand, the empirical approach for modelling pressure distribution is not based on physical laws, but on the parametrization of experimental data: correlation rules are established between the characteristics of the pressure evolution and the design and functional parameters of a specific family of pumps of different size. As a model application, the analysis of the wear and lubrication regime in the sliding contact between the vanes and the pressure ring is developed; this analysis is carried out through an original methodology based on Archard’s wear model, which associates the wear coefficient to the contact forces given by the empirical model, the wear rate and the material hardness, experimentally measured; the results are compared with the outcomes obtained from an EHD lubrication model in order to evaluate the film thickness and the lubrication regime. This method is applied to an industrial case in order to give indications for the proper selection of materials. As a general result, both modelling approaches give reliable results, useful for the analysis of the vibro-acoustic excitations, the optimization of the structural design, as well as the assessment of wear and lubrication regime. It is worth noting that, on the one hand, the lumped parameter approach allows the simulation of the behaviour of pumps of different type and design and makes it possible to account for a wide range of modifications, to be considered for optimization purposes. On the other hand, empirical models are less flexible than lumped parameter models, as they are applicable only to a single family of pumps; however, they represent efficient tools for R&D in industrial environment, due to faster development time and more friendly use.
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Jaouen, Tristan. "Caractérisation du cancer de la prostate de haut grade à l’IRM multiparamétrique à l’aide d’un système de diagnostic assisté par ordinateur basé sur la radiomique et utilisé comme lecteur autonome ou comme second lecteur." Electronic Thesis or Diss., Lyon, 2022. http://www.theses.fr/2022LYSE1140.

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Nous avons développé un système de diagnostic assisté par ordinateur (CAD) basé sur des régions d'intérêt pour caractériser le cancer de la prostate avec un grade de l'International Society of Urological Pathology (ISUP) ≥2 lors d'une IRM multiparamétrique (IRM-mp). Les paramètres de l'image provenant de 2 jeux de données multi-constructeurs de 265 IRM pré-prostatectomie et 112 IRM pré-biopsie ont été combinés en utilisant la régression logistique. Les meilleurs modèles contenaient le 2e percentile d’ADC (ADC2) et le taux de rehaussement normalisé (WI) dans la zone périphérique (ZP) et le 25e percentile d'ADC (ADC25) dans la zone de transition (ZT). Ils ont été associés dans le système CAD. Le CAD a été évalué rétrospectivement sur 2 jeux de données multi-constructeurs contenant respectivement 158 et 105 IRM pré-biopsie de notre institution (test interne) et d'une autre institution (test externe). Deux radiologues ont indépendamment décrit les lésions ciblées par la biopsie. Le score PI-RADSv2 (Prostate Imaging-Reporting and Data System version 2) attribué prospectivement lors de la biopsie et le score CAD ont été comparés aux résultats de la biopsie. A l’échelle des patients, les aires sous la courbe Receiver Operating Characteristic (AUC) du score PI-RADSv2 étaient de 82% (IC 95% : 74-87) et 85% (IC 95% : 79-91) dans les jeux de données de test interne et externe respectivement. Pour les deux radiologues, le score CAD avait des AUC similaires dans les jeux de données interne (82%, IC 95% : 76-89, p=1 ; 84%, IC 95% : 78-91, p=1) et externe (82%, IC 95% : 76-89, p=0.82 ; 86%, IC 95% : 79-93, p=1). La combinaison du PI-RADSv2 et du CAD aurait pu éviter 41 à 52% des biopsies tout en manquant 6 à 10% des cancers ISUP≥2. Le système CAD a confirmé sa robustesse dans une étude multicentrique impliquant 22 scanners et des protocoles d'imagerie très hétérogènes. Dans l'analyse par patient, le CAD et le PI-RADSv2 avaient des performances similaires en termes d’AUC (76%, IC 95% : 70-82 contre 79%, IC 95% : 73-86 ; p=0.34) et de sensibilité (86%, IC 95% : 76-96 contre 89%, IC 95% : 79-98 pour le PI-RADSv2≥4). La spécificité du CAD (62%, IC 95% : 53-70 contre 49% ; IC 95% : 39-59 pour le PI-RADSv2≥4) permettait une complémentarité avec le score PI-RADSv2 pour potentiellement éviter 50% des biopsies, tout en manquant 13% des cancers ISUP≥2. Ces résultats étaient similaires à ceux rapportés dans les cohortes de test issues d’un unique centre et ont ouvert la voie à de nouvelles applications du CAD. Le CAD a d’abord permis une bonne discrimination des cancers ISUP≥2 chez des patients placés en surveillance active. Son AUC (80% ; IC 95% : 74-86) était similaire à celle du score PI-RADSv2 attribué prospectivement par des uro-radiologues spécialisés (81%, IC 95% : 74-87 ; p=0.96). Le CAD était plus spécifique que les scores PI-RADS≥3 (p<0.001) et PI-RADS≥4 (p<0.001). Il pourrait offrir une solution pour sélectionner les patients pouvant éviter sans risque une biopsie de confirmation ou de suivi dans le cadre de leur surveillance active (25%). Il manquerait alors 5% des cancers ISUP≥2. Le CAD a enfin été confronté aux IRM-mp pré-prostatectomie de 56 patients japonais, issus d’une population qui est géographiquement éloignée de sa population d’entraînement et qui intéresse de par ses faibles taux d’incidence et de mortalité du cancer de la prostate. Son AUC était alors similaire au score PI-RADSv2 attribué par un radiologue expérimenté dans la ZP (80%, IC 95% : 71-90 contre 80%, IC 95% : 71-89 ; p=0.886) et dans la ZT (79%, IC 95% : 66-90 contre 93%, 95%CI : 82-96 ; p=0.051). Ces résultats prometteurs et robustes sur des jeux de données hétérogènes suggèrent que le CAD pourrait être utilisée dans la routine clinique quotidienne comme un second lecteur pour aider à sélectionner les patients pouvant éviter la biopsie en toute sécurité. Ce CAD pourrait aider les lecteurs moins expérimentés à caractériser les lésions de la prostate
We developed a region of interest-based (ROIs) computer-aided diagnosis system (CAD) to characterize International Society of Urological Pathology grade (ISUP) ≥2 prostate cancers at multiparametric MRI (mp-MRI). Image parameters from two multi-vendor datasets of 265 pre-prostatectomy and 112 pre-biopsy MRIs were combined using logistic regression. The best models used the ADC 2nd percentile (ADC2) and normalized wash-in rate (WI) in the peripheral zone (PZ) and the ADC 25th percentile (ADC25) in the transition zone (TZ). They were combined in the CAD system. The CAD was retrospectively assessed on two multi-vendor datasets containing respectively 158 and 105 pre-biopsy MRIs from our institution (internal test dataset) and another institution (external test dataset). Two radiologists independently outlined lesions targeted at biopsy. The Prostate Imaging-Reporting and Data System version 2 (PI-RADSv2) score prospectively assigned at biopsy and the CAD score were compared to biopsy findings. At patient level, the areas under the Receiver Operating Characteristic curve (AUC) of the PI-RADSv2 score were 82% (95% CI: 74-87) and 85% (95% CI: 79-91) in the internal and external test datasets respectively. For both radiologists, the CAD score had similar AUC results in the internal (82%, 95% CI: 76-89, p=1; 84%, 95% CI: 78-91, p=1) and external (82%, 95% CI: 76-89, p=0.82; 86%, 95% CI: 79-93, p=1) test datasets. Combining PI-RADSv2 and CAD findings could have avoided 41-52% of biopsies while missing 6-10% of ISUP≥2 cancers. The CAD system confirmed its robustness showing good discrimination of ISUP ≥2 cancers in a multicentric study involving 22 different scanners with highly heterogeneous image protocols. In per patient analysis, the CAD and the PI-RADSv2 had similar AUC values (76%, 95% CI: 70-82 vs 79%, 95% CI: 73-86; p=0.34) and sensitivities (86%, 95% CI: 76-96 vs 89%, 95% CI: 79-98 for PI-RADSv2 ≥4). The specificity of the CAD (62%, 95% CI: 53-70 vs 49%, 95% CI: 39-59 for PI-RADSv2 ≥4) could be used to complement the PI-RADSv2 score and potentially avoid 50% of biopsies, while missing 13% of ISUP ≥2 cancers. These findings were very similar to those reported in the single center test cohorts. Given its robustness, the CAD could then be exploited in more specific applications. The CAD first provided good discrimination of ISUP ≥2 cancers in patients under Active Surveillance. Its AUC (80%, 95% CI: 74-86) was similar to that of the PI-RADS score prospectively assigned by specialized uro-radiologists at the time of biopsy (81%, 95% CI: 74-87; p=0.96). After dichotomization, the CAD was more specific than the PI-RADS ≥3 (p<0.001) and the PI-RADS ≥4 scores (p<0.001). It could offer a solution to select patients who could safely avoid confirmatory or follow-up biopsy during Active Surveillance (25%), while missing 5% of ISUP≥2 cancers. Finally, the CAD was tested with the pre-prostatectomy mp-MRIs of 56 Japanese patients, from a population which is geographically distant from its training population and which is of interest because of its low prostate cancer incidence and mortality. The CAD obtained an AUC similar to the PI-RADSv2 score assigned by an experience radiologist in the PZ (80%, 95% CI: 71-90 vs 80%, 95% CI: 71-89; p=0.886) and in the TZ (79%, 95% CI: 66-90 vs 93%, 95%CI: 82-96; p=0.051). These promising and robust results across heterogeneous datasets suggest that the CAD could be used in clinical routine as a second opinion reader to help select the patients who could safely avoid biopsy. This CAD may assist less experience readers in the characterization of prostate lesions
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Cohen, Jérémie. "Stratégies diagnostiques des pharyngites de l'enfant : du test de diagnostic rapide aux règles de décision clinique." Thesis, Paris 5, 2014. http://www.theses.fr/2014PA05S011/document.

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Introduction – La place des tests de diagnostic rapide (TDR) et des règles de décision cliniques (RDC) pour le diagnostic des pharyngites à streptocoque du groupe A (SGA) chez l’enfant varie selon les recommandations internationales en raison de doutes sur la stabilité des performances diagnostiques du TDR et d’une validation insuffisante des RDC. Méthodes – Dans une étude prospective multicentrique (n=17) ambulatoire réalisée au sein du réseau clinique pédiatrique ACTIV de 2009 à 2011, 1776 enfants avec pharyngite ou sains ont été soumis à des prélèvements de gorge pour réaliser un TDR et une mise en culture (test de référence). Nous avons étudié l’effet indépendant de variables liées aux patients et aux médecins sur les performances diagnostiques du TDR, exploré systématiquement les faux-Positifs (FP) du TDR et réalisé une validation externe et une comparaison des RDC existantes. Résultats – La sensibilité du TDR (en moyenne 87%) variait selon la présentation clinique (âge, signes cliniques), l’inoculum bactérien et le phénomène de portage (paramètres aussi liés entre eux), et selon des variables liées aux médecins (dont le type d’activité clinique). La valeur prédictive négative du TDR était élevée (autour de 90%) et stable. Les FP du TDR étaient positifs pour le SGA en PCR. Aucune RDC n’était satisfaisante en termes de calibration et de discrimination. Conclusion – Le TDR est suffisant pour le diagnostic de pharyngite à SGA si les cliniciens évaluent leurs propres performances et les améliorent si besoin. Aucune RDC ne peut être recommandée en pratique clinique en pédiatrie
Background – The roles of rapid antigen detection tests (RADT) and clinical prediction rules (CPR) for the diagnosis of group A streptococcus (GAS) in children with pharyngitis vary across international clinical guidelines. This might be related to unstable diagnostic accuracy of RADTs and insufficient validation of CPRs. Methods – In a prospective multicenter (n=17) office-Based study that took place in France within the ACTIV network between 2009 and 2011, 1776 children with pharyngitis or healthy controls underwent throat swabs to perform a RADT and a throat culture (reference standard). We assessed the independent effect of patient- and physician-Level characteristics on the accuracy of a RADT, systematically re-Analyzed RADT false-Positive results, and externally validated and compared existing CPRs. Results – RADT sensitivity (overall 87%) varied according to clinical signs and symptoms, bacterial inoculum size and GAS throat carriage (factors also related to each other), and according to physician-Level characteristics (including type of clinical practice). RADT negative predictive value was high (about 90%) and stable. RADT false-Positives were positive for GAS when using a new PCR technique. No CPR had sufficient performances regarding calibration and discrimination. Conclusions – RADTs are sufficient for diagnosing GAS pharyngitis if clinicians accept diagnostic accuracy monitoring and adequate training when needed. No CPR can be recommended for use in pediatrics
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RUSCIO, DANIELE. "Tempi di Reazione alla Guida: Il ruolo dei processi attentivi, decisionali ed emotivi sulle aspettative di pericolo in contesti reali e virtuali." Doctoral thesis, Università Cattolica del Sacro Cuore, 2014. http://hdl.handle.net/10280/2872.

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Lo scopo della presente ricerca è studiare il peso del fattore umano nei tempi di reazione alla guida. I tempi di reazione son stati studiati sin dalle origini della Psicologia sperimentale, tuttavia se applicati alla guida risulta obsoleto a causa delle specifiche condizioni in cui la reazione si svolge, ai cambiamenti del traffico moderno e ai nuovi dispositivi di supporto intelligente. In letteratura emerge chiaramente l’influenza sul tempo di reazione delle aspettative, della salienza della risposta, della percezione del rischio, dei carichi cognitivi e delle condizioni di rilevazione. La presente ricerca si prefigge di affrontare l’impatto e le modalità di influenza di questi aspetti psicologici sui tempi di reazione alla guida. In particolare i dati registrati in condizioni di guida ecologica reale saranno usati per a) studiare l’influenza delle aspettative sui processi attentivi, emozionali e di presa di decisione alla guida in risposta al pericolo, e b) per valutare l’influenza di diversi livelli di realismo di simulazioni e simulatori virtuali sui processi psicologici che determinano l’IPTR. I risultati mostrano differenze significative nelle diverse fasi che compongono l’IPTR nelle diverse condizioni. I simulatori di guida si sono rivelati avere una validità relativa, ma non assoluta rispetto ai processi attivati nelle condizioni ecologiche, dimostrandosi però in grado di ricreare e modificare coerentemente i processi di avvistamento del pericolo in funzione della prevedibilità dello stesso; rendendoli strumenti utili per l’apprendimento. La ricerca fornisce informazioni sul funzionamento dei processi cognitivi ed emotivi alla guida utili per la ricostruzione degli incidenti, la sicurezza e la prevenzione stradale.
The aim of the present research is to study the role of human factor in a salient driving ability for road accident prevention, that is reaction time to danger. Reaction times (RTs) have been investigated since the origin of experimental Psychology, however when applied to driving, the values became obsolete due to modern driving conditions and interaction with advance driving automatic systems and devices. The influence of expectation, urgency, risk perception, cognitive load and driving conditions on the process that determine RTs have been steadily proven in literature. The present research aims to tackle the influence of these factors on RTs while driving. In particular data measured in real-life driving are used to a) study the influence of expectation on attention, emotions and decision making process, and b) assess the influence of virtual settings with different levels of realism, on the psychological process that determine RTs. A specific task that manipulate driver’s expectations was created to assess the influence of attention and decision making process in the different context on RTs. Results show significant differences in the RTs phases, for different situation. Driving simulators with different levels of realism proved to not have absolute validity, but rather relative on the meanings and learning process in detecting danger and deciding what response foster; giving us interesting information for drivers education, road safety and accident reconstruction.
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29

RUSCIO, DANIELE. "Tempi di Reazione alla Guida: Il ruolo dei processi attentivi, decisionali ed emotivi sulle aspettative di pericolo in contesti reali e virtuali." Doctoral thesis, Università Cattolica del Sacro Cuore, 2014. http://hdl.handle.net/10280/2872.

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Lo scopo della presente ricerca è studiare il peso del fattore umano nei tempi di reazione alla guida. I tempi di reazione son stati studiati sin dalle origini della Psicologia sperimentale, tuttavia se applicati alla guida risulta obsoleto a causa delle specifiche condizioni in cui la reazione si svolge, ai cambiamenti del traffico moderno e ai nuovi dispositivi di supporto intelligente. In letteratura emerge chiaramente l’influenza sul tempo di reazione delle aspettative, della salienza della risposta, della percezione del rischio, dei carichi cognitivi e delle condizioni di rilevazione. La presente ricerca si prefigge di affrontare l’impatto e le modalità di influenza di questi aspetti psicologici sui tempi di reazione alla guida. In particolare i dati registrati in condizioni di guida ecologica reale saranno usati per a) studiare l’influenza delle aspettative sui processi attentivi, emozionali e di presa di decisione alla guida in risposta al pericolo, e b) per valutare l’influenza di diversi livelli di realismo di simulazioni e simulatori virtuali sui processi psicologici che determinano l’IPTR. I risultati mostrano differenze significative nelle diverse fasi che compongono l’IPTR nelle diverse condizioni. I simulatori di guida si sono rivelati avere una validità relativa, ma non assoluta rispetto ai processi attivati nelle condizioni ecologiche, dimostrandosi però in grado di ricreare e modificare coerentemente i processi di avvistamento del pericolo in funzione della prevedibilità dello stesso; rendendoli strumenti utili per l’apprendimento. La ricerca fornisce informazioni sul funzionamento dei processi cognitivi ed emotivi alla guida utili per la ricostruzione degli incidenti, la sicurezza e la prevenzione stradale.
The aim of the present research is to study the role of human factor in a salient driving ability for road accident prevention, that is reaction time to danger. Reaction times (RTs) have been investigated since the origin of experimental Psychology, however when applied to driving, the values became obsolete due to modern driving conditions and interaction with advance driving automatic systems and devices. The influence of expectation, urgency, risk perception, cognitive load and driving conditions on the process that determine RTs have been steadily proven in literature. The present research aims to tackle the influence of these factors on RTs while driving. In particular data measured in real-life driving are used to a) study the influence of expectation on attention, emotions and decision making process, and b) assess the influence of virtual settings with different levels of realism, on the psychological process that determine RTs. A specific task that manipulate driver’s expectations was created to assess the influence of attention and decision making process in the different context on RTs. Results show significant differences in the RTs phases, for different situation. Driving simulators with different levels of realism proved to not have absolute validity, but rather relative on the meanings and learning process in detecting danger and deciding what response foster; giving us interesting information for drivers education, road safety and accident reconstruction.
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Santos, Marisa da Silva. "Validação externa de modelos de predição de pneumonia pós cirurgia cardíaca." Universidade do Estado do Rio de Janeiro, 2010. http://www.bdtd.uerj.br/tde_busca/arquivo.php?codArquivo=1751.

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Este trabalho versa sobre a validação externa de um modelo para predição de pneumonias em pacientes submetidos a cirurgias cardíacas. Também apresenta uma revisão dos métodos e técnicas para análise crítica e avaliação de desempenho dos modelos preditivos em medicina e discorre sobre aplicações do nomograma. Método: Dados de uma série de 527 pacientes, consecutivamente submetidos a cirurgias cardíacas entre Junho de 2000 e Agosto de 2002, foram utilizados para desenvolver os modelos de prognósticos. Foram realizadas análise de regressão logística múltipla e árvore de classificação e regressão (CART) para identificar fatores preditivos para a ocorrência de pneumonia. Diversos fatores de risco simples e convencionais pré-operatórios foram avaliados. Os modelos foram validados internamente com um método de bootstrap Um nomograma foi desenvolvido para melhorar a aplicabilidade clínica. O desempenho do nomograma foi avaliado por meio de medidas de calibração, discriminação e indicadores globais. Em uma segunda etapa estudo em um hospital público foi realizado com 333 pacientes adultos submetidos a cirurgias cardíacas entre Outubro de 2006 e Maio de 2007. Modelos construídos previamente por meio de regressão logística (LRM) e árvore de classificação e regressão (CART) foram validados com dados externos. Resultados: Um modelo de nomograma simples foi desenvolvido e validado internamente, mostrando discriminação moderada e boa calibração (AUC 0,79; escore Brier 0,064, ângulo de discriminação 0,13; Hosmer-Lemeshow p = 0,27). Pneumonia ocorreu em 7,6% dos pacientes da amostra de validação externa. LRM apresentou melhor desempenho com baixa discriminação (R2 7,1%, Brier=0,06, AUC=0,694) e com calibração adequada (Hosmer-Lemeshow p=0,08). Conclusões: As probabilidades preditas mostraram concordância global com a freqüência observada de pneumonia após cirurgia cardíaca. O nomograma forneceu uma predição satisfatória da probabilidade de pneumonia. Sua aplicabilidade para o uso clínico pode facilitar a informação do paciente e do cirurgião antes da cirurgia cardíaca. Foi validado externamente um modelo capaz de identificar pacientes de alto risco para pneumonia submetidos à cirurgias cardíacas. CART apresentou um bom desempenho na derivação e maiores perdas do que LRM, quanto à discriminação e calibração, na amostra de validação.
This study concerns the external validation of a prediction model for pneumonias after cardiac surgery. It also presents a review of methods and techniques for critical appraisal and performance assessment of clinical predictive models and nomogram applications. Methods: A consecutive series of 527 patients who underwent cardiac surgeries between June 2000 and August 2002 was used to develop a prognostic model.. Multiple logistic regression analysis was performed to predict the occurrence of pneumonia. Diverse simple and conventional preoperative risk factors were evaluated. The model was internal validated with bootstrap. A nomogram was developed to enhance clinical applicability. The performance was evaluated by calibration, discrimination and global measures. Prospective study was done to validate models predicting pneumonia after cardiac surgery with 333 adult patients who underwent cardiac surgery from October 2006 to May 2007. Previously constructed logistic regression (LRM) and classification and regression tree (CART) models were validated with external data. Results: a simple nomogram model was developed and showing low discrimination and good calibration (AUC 0.79, Brier score 0.064, discrimination slope 0.13, Hosmer-Lemeshow p=0.27). Pneumonia occurred in 7.5% of patients in the external validation set. LRM performed better with moderate discrimination (R2 7.1%, Brier=0.06, AROC=0.694) and calibration (Hosmer-Lemeshow P=0.08). Conclusions: Overall agreement between the predicted probabilities and observed frequencies was good in the development and the internal validation set. The nomogram predicts the probability of pneumonia for individual patients and may help in informing patients and surgeons before undergoing cardiac surgery. We validated a model that can identify which patients undergoing cardiac surgery are at high risk for pneumonia. CART performs well in derivation, and looses more discrimination and calibration than LRM in the validation set.
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Ouendo, Edgard-Marius D. "Indigence et soins de santé primaires en République du Bénin: approche de solutions au problème d'identification des indigents dans les formations sanitaires publiques." Doctoral thesis, Universite Libre de Bruxelles, 2005. http://hdl.handle.net/2013/ULB-DIPOT:oai:dipot.ulb.ac.be:2013/211005.

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Introduction: Du fait des faibles résultats enregistrés par différents systèmes de santé dans le monde, la conférence d'Alma Ata de 1978 avait préconisé l’approche des Soins de Santé Primaires. Pour renforcer cette approche et faciliter l’accessibilité universelle aux soins, l’Initiative de Bamako fut adoptée en 1987. Cette initiative se fonde sur la participation financière des patients aux soins. L'une des conséquences est le coût financier des soins pour les bénéficiaires avec un risque d'exclusion de certains patients. Mais l’Initiative de Bamako suggère les dispositions à prendre pour éviter l'exclusion des indigents. Au Bénin, les comités de gestion des centres de santé ont la responsabilité de veiller à l'accès aux soins des indigents. Mais malgré cela, la prise en charge des indigents n’est pas effective. Les professionnels de la santé se plaignent de ne pas disposer de critères d'identification des indigents. Sur cette base, l'identification des indigents constitue la pierre angulaire de leur prise en charge. En conséquence, la mise en place d'une stratégie opérationnelle fondée sur l'identification des indigents par les personnes ressources de la communauté et soutenue par un outil quantitatif d'identification, permet une identification fiable des indigents en vue de leur prise en charge sanitaire.

Méthode: Après un état des lieux de la situation des indigents dans le système de santé au Bénin, trois études ont été réalisées pour approfondir la question des indigents;

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Doctorat en Sciences de la santé publique
info:eu-repo/semantics/nonPublished

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32

Guillot, Mathieu. "Conception et validation d'une matrice 2D de détecteurs à fibres scintillantes plastiques pour la dosimétrie en radiothérapie externe." Thesis, Université Laval, 2013. http://www.theses.ulaval.ca/2013/29962/29962.pdf.

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Cette thèse porte sur le développement et la caractérisation d’une matrice 2D de détecteurs à fibres scintillantes plastiques pour la dosimétrie des faisceaux de photons d’énergie mégavoltage utilisés en radiothérapie. Les propriétés visées lors de la conception du détecteur matriciel furent la justesse, l’équivalence à l’eau, une bonne résolution spatiale, un nombre élevé de détecteurs, et une lecture à haute fréquence des doses déposées. La première partie de cette thèse fut consacrée à améliorer la justesse de la méthode spectrale utilisée pour corriger l’effet Cerenkov. Deux procédures aptes à extraire de façon juste les coefficients d’étalonnage ont été développées. Les résultats ont montré que cette méthode peut corriger l’effet Cerenkov avec une justesse de 1%. La seconde partie de cette thèse fut consacrée à la conception, la réalisation et la validation d’un détecteur matriciel composé de 781 dosimètres insérés dans un fantôme eau-équivalent. Un système optique a aussi été développé. Il fut déterminé qu’en moyenne, l’écart-type des mesures est inférieure à 1 % pour les doses supérieures à 6.3 cGy. Il fut aussi démontré que les distributions de dose ne sont pas perturbées (à +/- 1.1 %) par la présence des dosimètres à l’intérieur du fantôme. La caractérisation de la dépendance angulaire a révélée que les incidences des faisceaux ont peu d’impact sur la justesse des mesures. Le détecteur matriciel a aussi été validé dans le contexte de la radiothérapie à intensité modulée (IMRT). Onze plans de traitement ont été mesurés et les résultats ont montré d’excellents accords avec les doses calculées à l’aide d’algorithmes convolution-superposition ou mesurées avec des films radiochromiques. La sensibilité et la spécificité du détecteur matriciel aux erreurs de position d’une lame et d’un banc de lame d’un collimateur multi-lames (MLC) ont été déterminées en appliquant la théorie de détection du signal. Cette étude conclut que les dosimètres à fibres scintillantes plastiques pourraient permettre d’améliorer la qualité de la dosimétrie en IMRT, en raison de leurs avantages par rapport aux autres dosimètres, tels que l’équivalence à l’eau, une haute résolution spatiale, la lecture à haute fréquence, et une très faible dépendance angulaire.
This thesis deals with the development and characterization of a 2D array of plastic scintillation detectors for the dosimetry of megavoltage energy photon beams used in radiation therapy. The characteristics sought with the detector array are accuracy, water-equivalence, a good spatial resolution, a large number of detectors and a high frequency readout of the doses deposited. The first part of this thesis is devoted to the improvement of the accuracy of the spectral method used to correct the Cerenkov effect. A study has determined the optimal attenuation characteristics for the optical fibers and two procedures able to accurately extract the calibration coefficients were developed. Measurements performed in various situations showed that this method can correct the Cerenkov effect with an accuracy of 1 %. The second part of this thesis relates to the design, realization and validation of a detector array consisting of 781 plastic scintillation detectors inserted vertically into a plane of a water-equivalent phantom. An novel optical system was also designed. It was determined that, on average, the standard deviation of measurements is smaller than 1 % for doses deposited greater than 6.3 cGy. It was also demonstrated that the dose distributions are not perturbed (within +/- 1.1 %) by the presence of the detectors inside the phantom. The characterization of the angular dependence showed that the incidences of radiation beams have very little effect on the accuracy of measurements. The detector array was also validated in the context of intensity-modulated radiation therapy (IMRT). Eleven treatment plans were measured and the results showed excellent agreements with dose distributions calculated with convolution-superposition algorithms or measured with radiochromic films. The sensitivity and specificity of the detector array to position errors of one leaf and one leaf bank of a multileaf collimator (MLC) were also determined by applying the principles of signal detection theory. The study concluded that plastic scintillation detectors could allow improving the quality of dosimetry in IMRT, due to their advantages compared to other dosimeters, such as water-equivalence, high frequency readout, high spatial resolution and a very low angular dependence.
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Boissard, Philippe. "Dosimétrie in vivo en radiothérapie externe avec imageurs portals au silicum amorphe : de la méthode à la validation clinique." Toulouse 3, 2012. http://thesesups.ups-tlse.fr/1676/.

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La dosimétrie in vivo en transmission réalisée avec les imageurs portals apparait être une alternative intéressante pour la réalisation de la dosimétrie in vivo en Radiothérapie externe. Une nouvelle méthode basée sur des fonctions de Rapport Tissue Maximum finit (RTMf) et sur une séparation Primaire / Diffusée est proposée. La dose dans le patient peut alors être estimée à partir du signal transmis mesuré pendant le traitement. 46 configurations test réalisées à l'aide de fantômes d'eau solide ont été proposées pour réaliser l'évaluation globale de la méthode. En outre, une étude clinique de validation a été conduite pour 494 patients. Les images portals ont été acquises à l'aide d'imageur portals au silicium amorphe montés sur des accélérateur Clinacs Varian(tm). La dose dans le patient est calculée par rétroprojection de la dose portal à l'aide du logiciel EPIgray(tm) (logiciel développé en collaboration avec la société DOSIsoft(tm)) et est comparée à celle planifiée à l'aide logiciel Eclipse Varian(tm) (algorithme Pencil Beam). Les écarts entre les doses planifiées et les dose mesurées sont reportés pour chaque point d'intérêt. Les résultats sont dans les niveaux de tolérances habituels de la dosimétrie in vivo (moyenne=0. 7% 1s= 2. 7% pour les mesures sur fantômes; moyenne =-0. 6% 1s= 2. 8% pour les mesures in vivo sur patients). Pour conclure, la dosimétrie in vivo en transmission est facile à utiliser en conditions de routine clinique (pas de temps additionnels lors du traitement). En utilisant la méthode proposée, la dose peut être calculée en tous points dans le patient. La précision des résultats est plus qu'acceptable pour le cadre de la dosimétrie in vivo
Transit dosimetry performed with Electronic Portal Imaging Devices (EPIDs) appears as an interesting alternative for in vivo dose verification for patients receiving external Radiotherapy. A new method based on a transit Tissue Maximum Ratio (TMRt) and Primary/Scatter separation is proposed. The dose inside the patient could be estimated from the transmitted signal measured during irradiation. 46 test cases were defined, using solid water phantoms, for the overall method assessment. Moreover, a clinical study was driven for 494 patients. Portal Images are acquired using a-Si EPID mounted on 4 Varian Clinacs(tm). The dose in the patient is estimated from the back projection of the portal dose with EPIgray(tm) (software developed in a partnership with DOSIsoft(tm)) and compared with calculated data (Varian Eclipse(tm) software using pencil beam algorithm). Deviations between stated and measured doses are reported for each point of interest. The results are within the accepted tolerance of classical in vivo dosimetry (mean=0. 7% 1SD= 2. 7% for in-phantom dose verifications; mean =-0. 6% 1SD= 2. 8% for in vivo dose verifications). To conclude, transit dosimetry is easy to use systematically in clinical routine (no additional time for data acquisition). Using this method, the in vivo dose can be computed at any point. The accuracy of this method was more than acceptable for in vivo purpose
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El, Hage Mhamad. "Etude de la qualité géomorphologique de modèles numériques de terrain issus de l'imagerie spatiale." Phd thesis, Conservatoire national des arts et metiers - CNAM, 2012. http://tel.archives-ouvertes.fr/tel-00780682.

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La production de Modèles Numériques de Terrain (MNT) a subi d'importantes évolutions durant les deux dernières décennies en réponse à une demande croissante pour des besoins scientifiques et industriels. De nombreux satellites d'observation de la Terre, utilisant des capteurs tant optiques que radar, ont permis de produire des MNT couvrant la plupart de la surface terrestre. De plus, les algorithmes de traitement d'images et de nuages de points ont subi d'importants développements. Ces évolutions ont fourni des MNT à différentes échelles pour tout utilisateur. Les applications basées sur la géomorphologie ont profité de ces progrès. En effet, ces applications exploitent les formes du terrain dont le MNT constitue une donnée de base. Cette étude a pour objectif d'évaluer l'impact des paramètres de production de MNT par photogrammétrie et par InSAR sur la qualité de position et de forme de ces modèles. La qualité de position, évaluée par les producteurs de MNT, n'est pas suffisante pour évaluer la qualité des formes. Ainsi, nous avons décrit les méthodes d'évaluation de la qualité de position et de forme et la différence entre elles. Une méthode originale de validation interne, qui n'exige pas de données de référence, a été proposée. Ensuite, l'impact des paramètres de l'appariement stéréoscopique, du traitement interférométrique ainsi que du rééchantillonnage, sur l'altitude et les formes, a été évalué. Finalement, nous avons conclu sur des recommandations pour choisir correctement les paramètres de production, en particulier en photogrammétrie.Nous avons observé un impact négligeable de la plupart des paramètres sur l'altitude, à l'exception de ceux de l'InSAR. Par contre, un impact significatif existe sur les dérivées de l'altitude. L'impact des paramètres d'appariement présente une forte dépendance avec la morphologie du terrain et l'occupation du sol. Ainsi, le choix de ces paramètres doit être effectué en prenant en considération ces deux facteurs. L'effet des paramètres du traitement interférométrique se manifeste par des erreurs de déroulement de phase qui affectent principalement l'altitude et peu les dérivées. Les méthodes d'interpolation et la taille de maille présentent un impact faible sur l'altitude et important sur ses dérivées. En effet, leur valeur et leur qualité dépendent directement de la taille de maille. Le choix de cette taille doit s'effectuer selon les besoins de l'application visée. Enfin, nous avons conclu que ces paramètres sont interdépendants et peuvent avoir des effets similaires. Leur choix doit être effectué en prenant en considération à la fois l'application concernée, la morphologie du terrain et son occupation du sol afin de minimiser l'erreur des résultats finaux et des conclusions.
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35

Servagi-Vernat, Stéphanie. "Etude dosimétrique et évaluation de fonctions objectives développées en radiothérapie externe : application à la validation d'une nouvelle technique en radiothérapie." Thesis, Besançon, 2014. http://www.theses.fr/2014BESA2078/document.

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L’objectif principal de notre travail était d’évaluer deux nouvelles technologies, l’arcthérapie par la technique Rapid’Arc de chez Varian Medical System® et l’irradiation hélicoïdale avec Tomotherapy Hi-Art de chez Accuray® dans les tumeurs des Voies Aéro-Digestives Supérieures. Dans un premier temps, nous avons montré que ces 2 techniques étaient équivalentes du point de vue de la délivrance de la dose à partir de cas théoriques (30 cas) mais également in vivo à partir d’une population de patients analysée de façon prospective dans le cadre de l’étude nationale ARTORL (115 cas). Puis, nous avons cherché à augmenter le ratio thérapeutique en combinant l’une de ces 2 techniques avec des nouvelles techniques d’irradiation en conditions stéréotaxiques (Cyberknife d’Accuray® et Vero de Brainlab®). Nous avons étudié ensuite la toxicité radio-induite la plus fréquente dans notre population, à savoir la xérostomie. Aucun facteur prédictif de toxicités n’a pu être mis en évidence. Toutefois, nous avons pu créer un modèle prédictif de la fonction de récupération de la glande sous maxillaire, celles-ci étant souvent moins bien protégées. L’ensemble de ces résultats confirme les capacités « conformationnelles » de ces 2 nouvelles techniques innovantes et de leurs équivalences d’un point de vue dosimétrique et surtout clinique. Par ailleurs, cette équivalence dosimétrique de ces deux machines a également été retrouvée dans l’irradiation de tumeur pelvienne, dans le cadre de l’étude prospective ARTPELVIS. Le suivi ultérieur de ces populations permettra de confirmer l’équivalence clinique de ces 2 techniques d’un point de vue carcinologique
The main objectif of our work was to assess two new technologies, arctherapy by Rapid'Arc technology from Varian Medical System® and helical irradiation with Tomotherapy Hi-Art, Accuray® in Head and Neck cancer. First, we showed that these 2 techniques were equivalent in terms of dose delivery from theoretical cases (30 cases), but also in vivo from a population of patients analyzed prospectively included in the national study ARTORL (115 cases). Then, we tried to increase the therapeutic ratio by combining one of these 2 techniques with new techniques for stereotactic irradiation (Cyberknife of Accuray® and Vero Brainlab®). We then studied the most common toxicity in our population, ie xerostomia. No predictif factor could be highlighted. However, we were able to create a predictive model of the recovery function of the sub-mandibular gland, they tend to be less well protected. All these results confirm the "conformational" capacity of these two new innovative techniques, their equivalences dosimetric and especially clinically. These results were confirmed in an another location in the prospective study ARTPELVIS. Subsequent monitoring of these populations will confirm the clinical equivalence of these new technologies
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Timoumi, Youssef. "Influence des contraintes externes et de la charge en frigorigène sur le fonctionnement d'un groupe frigorifique : validation de modèles thermiques d'échangeurs." Paris 12, 1986. http://www.theses.fr/1986PA120021.

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Un groupe frigorifique ciat rb 35 a ete place dans seize situations de fonctionnement differentes, pour des charges comprises entre 1300 et 2100 grammes. Au total 118 regimes de fonctionnement ont ete etudies et les resultats experimentaux stockes en bibliotheque de donnees. L'analyse de ces donnees a permis les etudes suivantes: analyse des conditions de fonctionnement et de performance du groupe en fonction des parametres de reglage externes, l'analyse de l'influence de la charge en frigorigene a contraintes externes egales, amelioration des modelisations thermiques d'echangeurs a changement de phase
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Timoumi, Youssef. "Influence des contraintes externes et de la charge en frigorigène sur le fonctionnement d'un groupe frigorifique validation de modèles thermiques d'échangeurs /." Grenoble 2 : ANRT, 1986. http://catalogue.bnf.fr/ark:/12148/cb37601550j.

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38

Idani, Akram. "B/UML : Mise en relation de spécifications B et de descriptions UML pour l'aide à la validation externe de développements formels en B." Phd thesis, Université Joseph Fourier (Grenoble), 2006. http://tel.archives-ouvertes.fr/tel-00118718.

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Les exigences qui s'appliquent aux composants logiciels et aux logiciels embarqués justifient l'utilisation des meilleures techniques disponibles pour garantir la qualité des spécifications et conserver cette qualité lors du développement du code. Les méthodes formelles, et parmi elles la méthode B, permettent d'atteindre ce niveau de qualité. Cependant, ces méthodes utilisent des notations et des concepts spécifiques, qui génèrent souvent une faible lisibilité et une difficulté d'intégration dans les processus de développement et de certification. Ainsi, proposer des environnements de spécification, de développement de programmes et de logiciels, combinant des méthodes formelles et des méthodes semi-formelles largement utilisées dans les projets industriels, en l'occurrence B et UML, s'avère d'une grande importance. Notre intérêt porte précisément sur la méthode B qui est une méthode formelle utilisée pour modéliser des systèmes et prouver l'exactitude de leur conception par raffinements successifs. Mais les spécifications formelles sont difficiles à lire quand elles ne sont pas accompagnées d'une documentation. Cette lisibilité est essentielle pour une bonne compréhension de la spécification, notamment dans des phases de validation ou de certification. Aujourd'hui, en B, cette documentation est fournie sous forme de texte, avec, quelquefois, des schémas explicitant certaines caractéristiques du système. L'objectif de ce travail de thèse est de mettre en relation des spécifications en B avec des diagrammes UML, qui constituent un standard de facto dans le monde industriel et dont le caractère graphique améliore la lisibilité. Nous avons axé notre processus de dérivation de diagrammes de classes à partir de spécifications B autour d'une technique d'ingénierie inverse guidée par un ensemble de correspondances structurelles et sémantiques spécifiées à un méta-niveau. Quant à la dérivation de diagrammes d'états/transitions, elle a été orientée vers une technique d'abstraction de graphes d'accessibilité construits par une exploration exhaustive du comportement de la spécification.
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39

Chemingui, Makram. "Conceptualisation et validation d'une échelle de mesure de la qualité des travaux d'audit externe et interne : application selon la démarche du paradigme de Churchill." Besançon, 2004. http://www.theses.fr/2004BESA0001.

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L'approche traditionnelle de la qualité de l'audit débouche sur une incapacité à évaluer la pertinence des travaux d'audit menés. Nous estimons que le contrôle de la qualité de l'audit doit désormais se situer au niveau de la mise en œuvre. Il s'agit désormais de mesurer l'adaptabilité des travaux d'audit réalisés aux zones de risque de l'entreprise. L'objectif principal de cette thèse est de développer des échelles de mesure des travaux d'audit interne et externe permettant l'expérimentation de cette nouvelle approche d'évaluation. En se limitant à une vision " contractualiste " de la firme, la conception et la validation des échelles de mesure sont réalisées dans le cadre d'un protocole expérimental selon le paradigme de Churchill. Articulant des phases quantitatives basées sur deux questionnaires de recherche (141 répondants) et des phases qualitatives (entretiens avec les experts de l'audit), cette démarche a démontré la fiabilité et la validité de la majorité des échelles obtenues
The traditional approach of audit quality is today unable to allow a real evaluation of the adequacy of the audit tasks realized. We believe that the control of audit quality must now repose on the adequacy of the audit programs to the risks facing the firm. The main aim of this thesis is to develop scales, for measuring internal and external audit tasks, which will enable to experiment this new evaluation approach. By considering only the "contractualist" vision of the firm, the design and validation of measurement scales are realised within the framework of an experimental protocol according to Churchill's paradigm. This approach has confirmed the reliability and validity of the majority of the scales obtained, by linking up two distinctive phases: quantitative phases based on two research questionnaires (141 respondents) and qualitative phases based on interviews with audit experts
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Lippy, Robert D. "Development of the seasonal beliefs questionnaire : a measure of cognitions specific to seasonal affective disorder /." Download the thesis in PDF, 2005. http://www.lrc.usuhs.mil/dissertations/pdf/Lippy2005.pdf.

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41

Redelsperger, Jean-Luc. "Elaboration et validation d'un modele tridimensionnel de convection profonde atmospherique : application au cas des lignes de grains tropicales." Paris 6, 1987. http://www.theses.fr/1987PA066199.

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Un modele numerique anelastique et non hydrostatique est developpe dans le but de simuler la convection atmospherique profonde. Apres un ensemble de tests de sensibilite, le modele est applique a un cas de ligne de grains tropicale observee durant l'experience copt 81. Les resultats de la simulation sont compares statistiquement aux observations de radars doppler, montrant un tres bon accord. Une description detaillee de la ligne de grains est donnee (courant de gravite, organisation des courants ascendants et descendants, influence de la partie stratiforme), ainsi qu'une analyse detaillee des bilans dynamiques et thermodynamiques
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42

Page, Jonathan. "Développement et validation de l'application de la force de Lorentz dans le modèle aux moments entropiques M1. Étude de l'effet du champ magnétique sur le dépôt de dose en radiothérapie externe." Thesis, Bordeaux, 2018. http://www.theses.fr/2018BORD0248/document.

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La majorité des patients atteints d'un cancer sont soignés par la technique de la radiothérapie, l'une des trois principales modalités de traitement avec la chirurgie et la chimiothérapie. Elle consiste en la délivrance d'une radiation de haute énergie sur un volume cible. Son but est de détruire les cellules cancéreuses sans endommager les tissus sains. En pratique, on utilise divers outils numériques afin de prévoir de quelle manière sera déposée l'énergie dans le corps du patient. Ces méthodes peuvent néanmoins présenter des imprécisions ou un temps de calcul trop long pour leur utilisation en milieu clinique. Par conséquent, nous avons développé un nouveau modèle permettant de simuler le transport et le dépôt d'énergie de particules dans des tissus humains, de manière rapide et précise. De nouvelles installations permettant de traiter les patients de cette manière tout en effectuant une imagerie par résonance magnétique entrent actuellement sur le marché. Les champs magnétiques induits par cette technique ont pour effet secondaire et délétère de dévier les particules chargées, injectées ou créées dans le milieu, pouvant modifier fortement le dépôt d'énergie. Malgré cela, il n'existe actuellement pas de modèle permettant de rendre compte de ces effets de manière précise et rapide. Nous nous proposons d'introduire les effets magnétiques dans notre modèle afin de répondre à cette problématique. Nous appuyons la validation de notre modèle par des comparaisons numériques avec un code Monte-Carlo de référence, FLUKA, ainsi que par des comparaisons expérimentales effectuées à l'Institut Bergonié
The majority of patients diagnosed with cancer are treated by radiotherapy, one of the principal treatment modality with surgery and chemotherapy. It consists in the delivery of high energy radiation on a target volume. It aims to destroy the cancerous cells without damaging sane tissues. In clinical practice, numerical tools are used in order to predict how the energy will be deposited in the patient's body. However, these methods can lack of accuracy or cost too much in terms of calculation time to be suitable for clinical use. As a consequence, we developed a new model able to calculate the transport and energy deposition of ionizing particles in human tissues, efficiently and accurately. New installations allowing the treatment of patients by radiotherapy while imaging them by Magnetic Resonance Imagery are currently marketed. The magnetic fields induced by this technology have as secondary and noxious effect to deflect the charged particles injected or created in the target medium, which might modify highly the deposited energy. Despite that, there aren't yet commercially available numerical solution allowing to reproduce these effects accurately and quickly. We implemented the magnetic effects in our model to. We validate our model by numerical comparisons with a reference Monte-Carlo code, FLUKA, and with experimental comparisons led in the Bergonié Institute (Bordeaux)
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43

Knochel, Hervé. "Développement et validation d'un modèle numérique de circulation océanique à coordonnées [sigma] pour l'étude climatique de l'Atlantique nord." Université Joseph Fourier (Grenoble), 1998. http://www.theses.fr/1998GRE10256.

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Dans cette these, un modele numerique de circulation generale oceanique est mis en uvre dans le but d'effectuer une etude climatique de l'atlantique nord. Le modele presente la particularite d'utiliser une coordonnee verticale epousant le relief sous-marin (coordonnee ). Il inclut en outre un modele unidimensionnel integral de couche melangee de type krauss-turner pour parametriser la penetration des forcages atmospheriques de surface dans l'ocean. L'etude d'une simulation climatologique type montre la capacite du modele a reproduire les traits dominants de la circulation generale avec en particulier une representation realiste de la trajectoire du gulf stream et de son decollement a cape hatteras. Des etudes de sensibilite du modele sont egalement effectuees, mettant en evidence certains aspects caracteristiques, comme l'importance de la resolution verticale dans la representation de la circulation profonde ou l'amelioration de la penetration des forcages thermohalins du fait de l'utilisation du modele de couche melangee. Ces etudes de simulations climatologiques fournissent un etat climatique moyen de l'ocean, a partir duquel la variabilite interannuelle du modele est etudiee dans le cadre d'une simulation incluant des flux atmospheriques mensuels, issus de la reanalyse ncep/ncar entre 1958 et 1997. L'etude se concentre sur l'eau de la mer du labrador (lsw), montrant une variabilite interannuelle coherente de cette masse d'eau et validant ainsi de maniere tres positive les donnees de forcage du ncep/ncar. La simulation met de plus en evidence une inadequation du parametrage du forcage salin de surface. Malgre cela, le modele reproduit de maniere realiste les periodes observees de forte et faible convection en mer du labrador et fait apparaitre une propagation d'anomalies chaudes et froides dans la circulation cyclonique du gyre subpolaire.
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44

Mejia, Omar Asdrubal Vilca. "Predição de mortalidade em cirurgia de coronária e/ou valva no InCor: validação de dois modelos externos e comparação com o modelo desenvolvido localmente (InsCor)." Universidade de São Paulo, 2012. http://www.teses.usp.br/teses/disponiveis/5/5156/tde-11072012-113541/.

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Objetivo: Novas tendências na avaliação de risco trazem evidências de que modelos externos recalibrados ou remodelados funcionam melhor localmente. O objetivo deste estudo foi validar dois modelos externos e formular um modelo local, comparando-os na predição de mortalidade nos pacientes operados de coronária e/ou valva no InCor-HCFMUSP. Método: Entre 2007 e 2009, 3.000 pacientes foram sequencialmente operados de coronária e/ou valva no InCor-HCFMUSP. No banco de dados, foi realizada a validação dos modelos 2000 Bernstein-Parsonnet (2000BP) e EuroSCORE (ES), mediante testes de calibração e discriminação. O InsCor de 2.000 pacientes foi elaborado mediante a utilização de técnicas de bootstrap. Nos próximos 1.000 pacientes foi realizada a validação interna do modelo, e seu desempenho medido frente ao 2000BP e ES. Resultados: Houve uma diferença significativa na prevalência dos fatores de risco entre as populações do estudo, ES e 2000BP. Na validação externa dos modelos, o ES apresentou uma boa calibração (P=0,596); no entanto, o 2000BP revelou-se inadequado (P=0,047). Na discriminação, a área abaixo da curva ROC revelou-se boa para ambos os modelos, ES (0,79) e 2000BP (0,80). Utilizando a técnica de bootstrap, 10 variáveis: idade >70 anos, sexo feminino, cirurgia associada, infarto do miocárdio <90 dias, reoperação, cirurgia da valva aórtica, cirurgia da valva tricúspide, creatinina <2mg/dl, fração de ejeção <30% e estado pré-operátorio crítico (eventos), foram selecionadas para formulacão do InsCor. Na validação interna do InsCor, a calibração foi adequada, com P=0,184. Na discriminação, a área abaixo da curva ROC foi boa (0,79). Neste grupo, a área abaixo da curva ROC foi de 0,81 e 0,82 para o ES e 2000BP, respectivamente, mostrando-se apropriada para ambos os modelos. Conclusões: O InsCor e o ES tiveram melhor desempenho que o 2000BP em todas as fases da validação; pórem o novo modelo, além de se identificar com os fatores de risco locais, é mais simples e objetivo para a predição de mortalidade nos pacientes operados de coronária e/ou valva no InCor-HCFMUSP
Background: New trends in risk assessment bring evidence that recalibrated or remodeled external models work best locally. The aim of this study was to validate two external models and formulate a local model, comparing them to predict mortality in patients who underwent coronary bypass surgery and/or heart valve surgery at InCor-HCFMUSP. Method Between 2007 and 2009, 3.000 patients were sequentially operated to coronary bypass surgery and/or heart valve surgery at InCor-HCFMUSP. The database was assessment to validate the models 2000 Bernstein-Parsonnet (2000BP) and EuroSCORE (ES) through calibration and discrimination tests. The InsCor of 2,000 patients (2/3 of database) was elaborated using bootstrap techniques. Over the next 1000 patients (1/3 of database) the internal validation of the InsCor was performed and its performance compared against the 2000BP and ES. Results: Significant difference in the prevalence of risk factors was found among the external and study populations (P<0,001). In the external validation of these models, the ES showed good calibration (P = 0.596); however, 2000BP was inadequate (P = 0.047). In discrimination, the area under the ROC curve was good for both models, ES (0.79) and 2000BP (0.80). With the bootstrap technique, 10 variables: age> 70 years, female, CABG + valve surgery, myocardial infarction <90 days, reoperation, aortic valve surgery, tricuspid valve surgery, creatinine <2mg/dl, ejection fraction <30% and critical preoperative state (events) were chosen to formulate the InsCor. In the validation of InsCor, the calibration was appropriate with P = 0.184. In discrimination, the area under the ROC curve was good (0.79). In this group, the area under the ROC curve was 0.81 and 0.82 for ES and 2000BP, respectively, being suitable for both models. Conclusions: The InsCor and ES outperformed the 2000BP at all stages of validation, but the new model, besides identifying itself with the local risk factors, is more simple and objective for the prediction of mortality in patients who underwent coronary bypass surgery and/or heart valve surgery at InCor-HCFMUSP.
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45

Brendel, Karl. "Méthodes d'évaluation de modèles non linéaires à effets mixtes dans le cadre d'analyses de population en pharmacocinétique et pharmacodynamie." Paris 11, 2006. http://www.theses.fr/2006PA114823.

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Cette thèse est consacrée à l’évaluation des modèles non linéaires à effets mixtes pour les modèles de population en pharmacocinétique et/ou pharmacodynamie. Nous avons réalisé une revue systématique de la littérature de des analyses de population publiées entre 2002 et 2004. Nous avons ensuite développé différents critères permettant l’évaluation externe d’un modèle pharmacocinétique. Ces critères sont basés sur les observations, les hyperparamètres et la vraisemblance. Nous avons illustré ces différents critères en utilisant deux jeux de données simulés et un vrai jeu de données. Nous avons évalué par simulation les différents tests possibles sous H0 pour l’un de ces critères basé sur les observations, nommé erreurs de pédiction de distribution normalisées (NPDE). Nous nous sommes finalement intéressés au comportement des NPDE avec des covariables en simulant différents jeux de données de validation sans covariable, avec une covariable discrète ou une covariable continue
This thesis is about non-linear mixed effect models for population pharmacokinetic and/or pharmacodynamic analyses. We performed a survey of the literature on all the population analyses published between 2002 and 2004, in order to obtain an overview on the different evaluation methods. Secondly, we have developed and illustrated different metrics for external model evaluation. We illustared these different metrics by using two simulated datasets and one real dataset. These metrics are based on observations, hyperparameters and on the likelihood. We evaluated by simulation different tests under the null hypothesis, for one of the metric based on observations, called Normalized Prediction Distribution Error (NPDE). Finally, we illustrated the behaviour of the NPDE with covariate models, by simulating different validation datasets without covariate, with a categorical or a continuous covariate
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46

Lee, Ming-Hsun, and 李明勳. "Verification, Validation and Prediction in CFDwith Applications of Motor External Flow Simulations." Thesis, 2005. http://ndltd.ncl.edu.tw/handle/26992995486657978265.

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碩士
淡江大學
航空太空工程學系碩士班
93
The theme of research in this thesis is the motor external flow simulations with numerical method and calculation the flow rate then relatively prove each other with the experimental result. Carry on the numerical simulation in simplifying the motor at first, compare its result with the experiment of each other again, if the result of income within the range of acceptable, the step is verified to the true motor according to this. The motive of research in this thesis is because the flow rate and temperature rise of the motor can receiving the result with the experiment measure, but whenever alter the size of the component within the motor need to make the mould to cast again, really consume a lot of time and cost. So if can make good use of motor external flow simulations with numerical method, as long as revise its parameter in the computer that can receive the result, it can save a large amount of time and cost. Build the grid which constructs the way and define boundary condition by the simplifies motor, to understand when the true motor external flow simulations, how build it construct by good grid quality and define correct boundary condition it will be influencing solve. This thesis passes a series of simple internal flow motor、simple external flow motor、external flow motor and add four fins of heat dissipation、external flow motor and add twenty-four fins of heat dissipation with numerical simulation and experiment measure and true motor external flow, follow in order and advance step by step to establish a set of systematic verification procedure and by dealing with the course of simplifying motor, solve the uncertain factor with numerical and experiment, in order to set up good verification and validation norm.
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47

Fontenot, Jolie Carol. "Toward a communication-centered measure of organizational identification : initial scale development and validation of the C-OI." Thesis, 2006. http://hdl.handle.net/2152/23961.

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Due to the lack of an operationalization that centers on communication, the communication field has needed a measure that captures the unique elements interaction plays in the formation of organizational identification (OI). This dissertation offers an alternate conceptualization and operationalization of organizational identification designed to be communication-centered, and labels it Communicative Organizational Identification (C-OI). C-OI is a type of behavioral identification that is defined as the manifestation of solidarity with the values of a collective through verbal and nonverbal behaviors expressed to internal and external others. This measure was theorized as having 4 subscales: internal verbal communication, external verbal communication, internal nonverbal communication, and external nonverbal communication. To validate this measure, three rounds of data collection were utilized, ultimately reducing the measure from 46 to 10 items with three subscales: internal verbal, external verbal, and nonverbal. Both confirmatory factor analysis and exploratory factor analysis were used in examining underlying dimensions. This measure was shown to have acceptable levels of internal consistency (Chronbach’s [alpha] = .87), comparable to alternate measures of OI. Through the use of hierarchical multiple regression the C-OI measure and its subscales were shown to have at least some incremental validity in comparison to the Mael and Ashforth (1992) in predicting communication competence of co-workers, perceived organizational support, organization-based self-esteem, intent to quit, and organizational tenure. The C-OI measure also had incremental validity in comparison to the Cheney (1982) Organizational Identification Questionnaire (OIQ) in predicting organizational tenure. The C-OI’s three subscales also showed incremental validity over several existing measures. Through Pearson product moment correlations convergent validity was illustrated for the C-OI and its subscales. The C-OI does not focus on the decision-making elements of OI’s conceptualization (Cheney, 1982), nor does it attend to its role in motivation. This dissertation also used self-report measures, and the issue of common method bias could apply here. Future research is needed to validate further the measure of C-OI particularly in terms of establishing discriminant validity, and measuring multiple targets of identification.
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48

Moreira, Ana Catarina Freire. "Using Magnetic Resonance Images for planning treatments in External Radiotherapy - Validation procedures for planning "MRI-only"." Master's thesis, 2013. https://repositorio-aberto.up.pt/handle/10216/70932.

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49

Moreira, Ana Catarina Freire. "Using Magnetic Resonance Images for planning treatments in External Radiotherapy - Validation procedures for planning "MRI-only"." Dissertação, 2013. https://repositorio-aberto.up.pt/handle/10216/70932.

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50

"External Validation of an Instructional Design Model for High Fidelity Simulation: Model Application in a Hospital Setting." Doctoral diss., 2011. http://hdl.handle.net/2286/R.I.8948.

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abstract: The purpose of this study was to investigate the use of the design characteristics component of the Jeffries/National League for Nursing Framework for Designing, Implementing, and Evaluating Simulations when developing a simulation-based approach to teaching structured communication to new graduate nurses. The setting for the study was a medium sized tertiary care hospital located in the southwestern United States. Participants in the study were an instructional designer (who also served as the researcher), two graduate nursing education specialists, one unit based educator, and 27 new graduate nurses and registered nurses who had been in practice for less than six months. Design and development research was employed to examine the processes used to design the simulation, implementation of the simulation by faculty, and course evaluation data from both students and faculty. Data collected from the designer, faculty and student participants were analyzed for evidence on how the design characteristics informed the design and implementation of the course, student achievement of course goals, as well as student and faculty evaluation of the course. These data were used to identify the strengths and weaknesses of the model in this context as well as suggestions for strengthening the model. Findings revealed that the model generally functioned well in this context. Particular strengths of the model were its emphasis on problem-solving and recommendations for attending to fidelity of clinical scenarios. Weaknesses of the model were inadequate guidance for designing student preparation, student support, and debriefing. Additionally, the model does not address the role of observers or others who are not assigned the role of primary nurse during simulations. Recommendations for strengthening the model include addressing these weaknesses by incorporating existing evidence in the instructional design of experiential learning and by scaffolding students during problem-solving. The results of the study also suggested interrelationships among the design characteristics that were not previously described; further exploration of this finding may strengthen the model. Faculty and instructional designers creating clinical simulations in this context would benefit from using the Jeffries/National League for Nursing Model, adding external resources to supplement in areas where the model does not currently provide adequate guidance.
Dissertation/Thesis
Ph.D. Educational Technology 2011
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