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Adaptation to past changes in the climate of Britain may be indicative of the way in which society will respond to future climate change. The long run costs associated with climate change are, once full adaptation has occurred, not obviously detrimental. Furthermore even if the frequency of 'extreme events' such as floods and storms increases it is not apparent that these will necessarily be as detrimental to society as they currently might seem since society in effect chooses its exposure to extreme events. Some extreme events such as hard frosts are likely to decrease in frequency. The thesis uses the theory of hedonic prices to examine the role of climate variables in explaining differences in average residential land prices and wage rates relating to 127 English and Welsh counties, Scottish regions, metropolitan areas and London boroughs. Substantial evidence is found in favour of the hypothesis that compensating land price differentials exist for climate variables. An alternative approach to estimating amenity values is to argue that households respond in part to differing levels of environmental amenities by altering their patterns of consumption. This phenomenon can be given a 'Household Production Function' interpretation. Given the assumption of 'demand dependency' between climate variables and marketed commodities it is possible to determine the amenity value of climate change from market data. Using cross country data for 60 countries the analysis points unambiguously to the existence of a 'climatic optimum'. The hedonic technique can also be used as a means of determining the value to British agriculture of a marginal change in climate. In the hedonic approach sale price differentials between land characterised by different climates is given an interpretation in terms of underlying productivity differences. Data characterising over 400 separate transactions in farmland is analysed and the value of marginal changes in climatic variables computed. The analysis suggests that the financial value of climate variables to farmers could in some cases be quite high and also that changes in seasonal patterns and the frequency of 'extreme events' are quite important. The impact of climate change on the chosen destinations of British tourists is also investigated. Destinations are characterised in terms of various 'attractors' including climate variables, travel costs and accommodation costs. Together these variables are used to explain the observed pattern of overseas travel in terms of a model based on the precept of utility maximisation. This approach permits the changes in consumer surplus following climate change to be predicted and effectively identifies the 'optimal' climate for generating tourism. It is argued that British tourists are likely to experience a large gain in welfare in the sense that the attributes of nearby (low cost) locations improve following climate change. Finally, information on marginal willingness to pay for climatic amenities is combined with predictions concerning the scale and direction of possible climate change over Britain in order to provide a money measure of the welfare impact of such changes. Because households appear to prefer a climate characterised by much higher temperatures than currently prevail over Britain households reap large gains from climate change.

Cette étude concerne l'étude d'actionneurs à jets pulsés pour le contrôle de décollements sur une rampe. Des expériences de contrôle en boucle ouverte puis en boucle fermée ont été effectuées avec succès pour réattacher une couche limite turbulente épaisse . Ces tests ont été effectués dans la soufflerie de couches limites du LML (caractérisée par Carlier & Stanislas [2005]), celle-ci ayant la particularité d'avoir une couche limite dillatée permettant d'obtenir des nombre de Reynolds et des temps caractéristiques long. Différents nombre de Reynolds différent basés sur l'épaisseur de quantité de mouvement ont été testés gamme: (Re=75000-12600).Les tests de contrôle en boucle ouverte ont été menées dans la soufflerie pour sélectionner une entrée / sortie adaptée au problème de contrôle, pour identifier les échelles de temps du processus de décollement/réattachement, pour les modéliser, pour choisir les fréquence optimale et pour finalement les utilisées en contrôle en boucle fermée. Ensuite, des contrôleurs simples (Proportionnelle Intégrale (PI) et Régulateur Linéaire Quadratique (RLQ)) ont été implémentés en œuvre expérimentalement en boucle fermée et comparés à des simulations. La réactivité du contrôle, à vitesse de l'écoulement constante, est améliorée par rapport aux résultats en boucle ouverte. La robustesse des contrôleurs a été testée avec des variations de la vitesse de l'écoulement. Ces tests ont mit en évidence la nécessité de contrôleurs plus complexes. Dans cette optique, des contrôleurs robustes H∞, basés sur le modèle linéaire du premier ordre extrait des expériences en boucle ouverte, ont été conçu et simulés. Un modèle Linéaire à Paramètres Variables (LPV) a été proposé. Celui-ci tient compte des variations de la vitesse de l'écoulement. Finalement, un contrôleur robuste H∞ LPV a été proposé pour de future implémentations expérimentales, qui donne de bon résultats en dépit des variations de la vitesse de l'écoulement dans la gamme étudiée. / The current study deals with the employment of the pulsed jet actuators for flow separation over a ramp. Open and closed-loop control experiments were successfully performed to reattach a thick turbulent boundary layer, thanks to large scales of the facility (LML wind tunnel) characterized byCarlier and Stanislas [2005]. They were performed at three Reynolds numbers based on the momentum thickness of the turbulent boundary layer, varying from Re =7500 to 12600.Open-loop control were conducted in wind tunnel experiments to select an adequate input/output for the control problem, identify the time scales of the separation/attachment process, model the separated ow system under actuation, study the inuence of the actuation frequency and extractthe optimal frequencies in the range of study to be used in closed-loop control. Then, simple controllers (Proportional-Integral and Linear Quadratic Regulator) were experimentally implemented in closed-loop congurations and compared to simulations. The control reactivity at constant free stream velocity is improved compared to open-loop results. The robustness of thecontrollers is tested under variations of the free stream velocity, which highlights the need for more complex controllers.Robust H∞ controllers based on rst order model extracted in open-loop experiments, were designed and simulated. Linear Parameter Varying (LPV) model is proposed that takes into account free stream velocity variations. Then, a robust H∞ LPV controller is proposed, that performs well in spiteof free stream velocity variations in all the operating range.

Resumen La presente investigación se realizó en la Red de Salud de Barranco – Chorrillos – Surco que involucra 25 establecimientos de salud, durante los meses de enero a junio del 2009 y donde participaron todo el personal asistencial de la red, tomándose como parámetro de medición los niveles altos, medios y bajos según la escala del Maslach Bunout Inventory (MBI). El propósito de la investigación consistió en hallar la Prevalencía del Síndrome de Burnout y la identificación de los factores de riesgo asociados. El presente estudio se justificó por cuanto posee valor teórico, utilidad práctica, relevancia social, y en base a los beneficios netos que genera en salud pública y otras áreas. El estudio se sustenta en las investigaciones realizadas en nuestro País y en otros países. La metodología utilizada fue la de un estudio epidemiológico de tipo descriptivo-transversal, con la aplicación de un diseño de investigación de campo donde la población estuvo conformada por ochocientos veintiséis (826) trabajadores, de los cuales se tomo una muestra del 25% (180). La técnica de observación empleada fue la observación en la cual se aplicó una encuesta formada por 10 preguntas correspondientes a las variables sociodemográficas y el Maslach Bunout Inventory (MBI) que consta de 22 preguntas cerradas en escala de Lickert. El procesamiento de datos permitió determinar que la Prevalencía en el periodo estudiado fue del 12% y que los factores de riesgo asociados fueron la edad de 41-50 años, el estado civil sin pareja, de 0 a 2 hijos, ser técnico y/o auxiliar, tener un trabajo asistencial, la condición laboral de contratado, con un tiempo de servicio de 6 a 15 años, y con un tiempo en el trabajo actual de 6 a 10 años, tener un solo trabajo. En conclusión hallamos una Prevalencía del Síndrome de Burnout y factores de riesgo asociados.

A research report submitted to the Faculty of Science, in partial fulfilment of the requirements for the degree of Master of Science, University of the Witwatersrand, Johannesburg, 2014. / This study investigates to what extent and how teaching informed by variation theory could improve the Grade 11 learners’ interpretation of algebraic functions. The study adopted a learning study approach, where learner difficulties are elicited in a pre-test, and on the basis of the results of the pre-test, a lesson is planned, informed by variation theory, to make it possible for learners to discern what they found difficult. In this study, a pre-test on functions was given to three groups of Grade 11 learners (85 learners in all) in the researcher’s school that enabled the identification of aspects of functions learners found to be most problematic. The lesson was then taught successively to each group. A post-test at the end of each lesson, together with reflection on the lesson led to refinements for the next lesson to the next group. The study describes the changes made to the lessons, and the results of the pre and post tests for each of the three groups. The results showed that while each group improved in the post test, the third group outperformed the others, confirming that an intervention, informed by variation theory, did improved learning. All learners were afforded the opportunity to discern the object of learning and their interpretation of functions improved, with the third group improving the most. Keywords: object of learning, patterns of variation theory, interpretation of functions.

The present study aimed to explore whether demographic variables are predictors of labour review case outcomes. In order to investigate the aim of the present study, two research questions were put forward. The first question centered on whether demographic variables of the parties in a case, are predictors of reviews outcomes. In addition to looking at these broader patterns, the study also focused more specifically on whether the demographic variables of presiding officers predict the outcomes of reviews of CCMA cases. The present study is classified as archival in nature and is quantitative, non-experimental and an ex post facto design. The sample for the present research was gathered by analysing Labour Review Reports that was accessed through the University of the Witwatersrand Library. A sample of 100 case reports was gathered in order to make accurate inferences from the sample about the target population. A Chi-Square test of association was conducted on the data gathered. There was no significant in relation to gender, age and case outcomes. On the other hand, race of the judge, applicant and respondent did provide evidence of significance. However, as a result of insignificance, log linear modelling could not be conducted.

Cuando los valores posibles de una variable aleatoria son continuos y no negativos, incluyendo el valor cero con probabilidad no nula, la variable es denominada semicontinua o cero-in acionada y posiblemente sea pertinente suponer que presenta una distribución mixta de probabilidades constituida por una distribución de Bernoulli para explicar si la respuesta toma el valor cero o no y una distribución continua positiva para explicar si ésta última no es cero. En el análisis de regresión, el modelo de dos partes (MDP) es tradicionalmente usado para explicar una variable semicontinua. En el MDP la respuesta presenta este tipo de distribución mixta y sus parámetros son expresados de tal manera que posibilite estimar el efecto de un conjunto de covariables sobre la media de esta respuesta condicionada a que tome valores positivos y sobre la probabilidad de que la respuesta tome el valor cero. El objetivo de la tesis es estudiar un modelo alternativo al MDP, que llamaremos modelo de regresión cero-in acionada a la media (MCIM), cuya parametrización permita estimar e interpretar efectos de covariables sobre la media total de la respuesta, en lugar de la media condicionada a valores positivos. Además, optamos por la distribución gamma generalizada (MCIM-GG) para modelar ciertas características de los valores positivos de la respuesta, tales como, por ejemplo, la asimetría positiva y la curtosis pronunciada. Estas características, junto con el exceso de valores cero, son típicas en diferentes ejemplos de variables respuestas en la Economía y la Medicina. Los resultados del estudio de simulación muestran un adecuado desempeño de las estimaciones de máxima verosimilitud del MCIM-GG bajo diferentes escenarios de nidos según porcentajes de valores ceros de la respuesta y tamaños de muestra. Por último, los resultados de la aplicación muestran que el MCIM-GG puede tener un mejor ajuste a los datos respecto al MDP-GG, así como proporcionar una más directa interpretación de los efectos de ciertas covariables sobre la media de los gastos en educación de adolescentes participantes del estudio Niños del Milenio en el Perú. / Tesis

by Wai-kuen Wong. / Thesis (M.Phil.)--Chinese University of Hong Kong, 1993. / Includes bibliographical references (leaves 57). / Chapter Chapter 1 : --- Introduction --- p.1 / Chapter Chapter 2 : --- Estimation of Correlation between Censored and Polytomous Variables --- p.5 / Chapter 2.1 : --- Model --- p.5 / Chapter 2.2 : --- Maximum Likelihood Estimation between a Censored and a Polytomous Variable --- p.7 / Chapter 2.3 : --- Simulation Study --- p.14 / Chapter 2.4 : --- Extension to Several Variables --- p.18 / Chapter Chapter 3 : --- An application -- Correlation Structure Analysis --- p.33 / Chapter 3.1 : --- Model --- p.33 / Chapter 3.2 : --- Two-stage Estimation Procedure --- p.35 / Chapter 3.3 : --- Optimization Procedure --- p.37 / Chapter Chapter 4 : --- Conclusion --- p.40 / Tables --- p.42 / References --- p.57