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Governments, international agencies, and researchers routinely assess health and income inequalities and inequities so as to better communicate the evidence of their levels and trends to both policy-makers and the general public. Measuring the extent to which differences in health or income are unequal or unfair is, however, complex. This thesis contains three chapters centrally concerned with inequalities, though the focus differs across chapters. Chapter 2 helps address the gap between the requirements of indices often used for measuring income-related health inequality and current research practice by providing a non-technical review and critical assessment of the recent literature. This chapter should function as a guide for policy researchers and analysts to help them be more critical consumers of studies that use these indices while also helping applied researchers in choosing inequality measures that have the normative properties they seek. Most measures of inequality make assumptions about the extent to which society is averse to inequality. Moreover, analysts often assume that attitudes toward inequalities in health or income are the same. Chapter 3 is the first study using a mixed-methods approach to assess public attitudes toward inequalities in income, health, and income-related health inequality to determine preferences and how attitudes toward inequalities in these domains differ. Chapter 2 and 3 contribute to a greater understanding of the measurement and interpretation of inequalities. While chapters 2 and 3 focus on inequalities among individuals within a society, chapter 4 focuses on inequalities globally among societies. Chapter 4 examines global health inequalities that result from medical care use using the example of long-standing drug technologies for treating hypertension. The study links availability and affordability of blood-pressure-lowering medicines with individual use and health outcomes. Chapter 4, therefore, provides an empirical illustration on how country-specific policies can play an important role in either countering or exacerbating health differences. / Thesis / Doctor of Philosophy (PhD) / This thesis concerns itself with different aspects of inequality related to health and income, though the focus differs across chapters. The second and third chapters of this thesis contribute to a greater understanding of the measurement and interpretation of inequalities. Whereas the fourth chapter provides empirical evidence on how country-specific policies can counteract or exacerbate health differences. Chapter 2 comprehensively reviews and critically assesses the literature on the technical and normative properties of indices commonly used for measuring income-related health inequality thereby addressing the gap between the requirements of these indices and current research practice. Chapter 3 investigates public attitudes toward inequalities in income, health, and income-related health inequality to determine preferences and where attitudes toward these inequalities differ. Chapter 4 examines global health inequalities that result from medical care use using the example of long-standing drug technologies for treating hypertension and links availability and affordability of medicines with individual use and health outcomes.

Ce mémoire a pour objet d'observer s'il est théoriquement possible de distinguer les gens par la méthode qu'ils utilisent lorsque vient le temps de prendre des décisions en situation d'incertitude ainsi que lorsqu'il y a un phénomène de corrélation dans la probabilité que certains évènements surviennent dans ce même futur. En se basant sur le principe que l'agent qui prend une décision face au futur est rationnel, deux méthodes seront distinguées, soit l'équation de Bellman et la méthode de la valeur optionnelle. Cette dernière étant une approximation de la première. Dans ce document, il est démontré qu'il serait effectivement possible via une expérience de distinguer les deux types d'individus. Cette distinction est effectuée à l'aide du fait que les individus prennent des décisions différentes dans l'expérience, et ce, selon le type de méthode de calcul qu'ils utilisent pour prendre leurs décisions. Les résultats de ce mémoire sont robustes à l'aversion au risque des individus, mais également au fait que certaines personnes ne prennent pas en compte le phénomène de corrélation qui est présent.

Cette thèse propose une analyse des politiques de stabilisation des prix alimentaires dans les pays pauvres. Afin de représenter la situation dans ces pays, nous considérons dans un modèle de stockage à anticipations rationnelles que les consommateurs ne peuvent pas s'assurer contre le risque prix et qu'ils sont averses au risque. L'incomplétude de marché justifie l'intervention publique et des politiques optimales de stabilisation sont analysées. Une politique optimale de stockage publique implique une augmentation du niveau de stockage. Ce stockage additionnel entraîne l'évincement de tous les stockeurs privés en supprimant les opportunités de profit spéculatif. L'usage de règles complexes d'intervention publique étant peu probable dans des pays pauvres, nous comparons des politiques optimales de stockage alimentaire à des règles simples comme une subvention au stockage privé ou une bande de prix défendue par du stockage public. L'engagement du gouvernement entraîne des gains de bien-être par rapport à une politique discrétionnaire liés à la possibilité de manipuler les anticipations des producteurs et donc de les induire à stabiliser les prix. Les règles simples de stabilisation permettent d'obtenir des gains proches de ceux obtenus avec des politiques optimales. Dans un cadre d'économie ouverte, les instruments de stabilisation sont la politique commerciale et le stockage. Une politique de stockage non accompagnée d'une politique commerciale ne profite pas aux consommateurs, car les bénéfices de la stabilisation se dissipent sur le marché mondial. Au contraire, une politique commerciale optimale permet d'augmenter la stabilisation en exploitant le marché mondial.

Posttraumatic stress disorder (PTSD) is an anxiety disorder that may follow exposure to severe emotional trauma and presents with various symptoms of anxiety, hyperarousal and cognitive anomalies. Interestingly, only 10-30% of an exposed population will go on to develop full-blown PTSD. Cholinergic neurotransmission is implicated in anxiety as well as other typical manifestations of PTSD, particularly cognitive changes. The frontal cortex and hippocampus regulate and in turn are affected by stress, and have also been implicated in the underlying neuropathology of PTSD. These areas are densely innervated by cholinergic neurons originating from the basal forebrain. In this study, the time dependent sensitization (TDS) model was used to induce symptoms of PTSD in animals. The study was designed to determine the long-term effects of an intense, prolonged aversive procedure on central muscarinic acetylcholine receptor (mAChR) characteristics and the correlation if any of those findings to cognitive aspects and general arousal as characteristics associated with PTSD. In order to achieve this goal, male Sprague-Dawley rats were exposed to the TDS stress paradigm with behavioral/neuro-receptor assessments performed on day 7 post re-stress (duration of each experiment in whole is 14 days). Acoustic startle reflex (ASR) was used to determine emotional state (hyperarousal), while the conditioned taste aversion (CTA) paradigm was implemented in order to assess aversive memory. Muscarinic receptor binding studies were performed in the frontal cortex and hippocampus. Moreover, both the stress-exposed and control animals were pre-tested in the acoustic startle chamber in order to attempt to separate stress sensitive from stress-resilient animals based on predetermined ASR criteria. The ASR niodel was previously validated in our laboratory, while the CTA model was validated in this project before application. In the CTA model, an i.p. injection with lithium chloride (LiCl) (associated with digestive malaise), was used as unconditioned stimulus (US) and was paired with a saccharinlcyclamate drinking solution as conditioned stimulus (CS) to induce aversion to the novel taste (CS) when presented in the absence of the US. Population data of animals tested in the ASR experiment indicated no statistical significant difference between stressed and control animals. However, when each animal was assessed individually, 22.5 % of the exposed population displayed all increase above the predetermined criteria of 35 % in startle response, indicating a state of heightened arousal. In contrast, only 4.2 O h of control animals (no stress) displayed an increase in arousal based on the above mentioned criteria. Muscarinic receptor densities (Bm,) in the total population of animals exposed to stress showed a statistical significant increase in both the hippocampus and frontal cortex when compared to controls, with no changes in & values observed in either one of the areas. In the CTA experiment, TDS stress was implemented as US paired with a saccharinlcyclamate drinking solution as CS. An acute session of prolonged stress (as used in the TDS model) effectively induced aversion to a novel taste and a subsequent reminder of the stress (restress) paired with the CS sustained the acquire adversive memory. Furthermore, LiCl was reintroduced as US in order to assess the effect of prior exposure to two types of stress (acute and TDS) on subsequently acquired CTA memory. Prior exposure to acute stress had no significant effect on subsequently acquired aversive memory when measured either 3- or 7 days post-conditioning (CS-US). Stress-restress (TDS) exposure, however, indicated a significant decrease in aversive memory from 3- to 7 days post-conditioning (CS-US) as well as a significant decrease in aversive memory between the control- and the TDS group 7 days post-conditioning. The mAChR density (B,,) in the frontal cortex; but not in the hippocampus, was elevated at the same point in time (7 days post CS-US pairing) that CTA memory was impaired following TDS stress (stress-restress). Ultimately, these data support an association between altered cholinergic receptors and hyperarousallanxiety in an animal model of PTSD. The data also support the phenomenon of individual susceptibility to stress in animals that parallels that observed in humans exposed to severe trauma. Impaired aversive memory (CTA) is a consequence of prior exposure to TDS stress, but not acute stress, and is likewise mediated by an altered central cholinergic transmission displayed as an increase in mAChRs in the frontal cortex. The lack of studies regarding the influence of the cholinergic system in PTSD related behavior earns ,this project value as inimitable PTSD research. / Thesis (M.Sc. (Pharmacology))--North-West University, Potchefstroom Campus, 2007.

Thèse numérisée par la Direction des bibliothèques de l'Université de Montréal.

Contexte: Plusieurs études ont démontré que les indices environnementaux associés à la cigarette peuvent provoquer des envies de consommer (« cravings ») chez les fumeurs, ce qui nuit aux efforts d’abandon de la substance et favorise le maintien du tabagisme. Un bon nombre d’études en imagerie cérébrale ont examiné les bases neurophysiologiques de cette caractéristique clinique. Le tabagisme se caractérise aussi par l’incapacité des représentations négatives de la consommation (méfaits médicaux et sociaux) d’influencer la consommation des fumeurs. Étonnamment toutefois, très peu de travaux de recherche se sont intéressés à examiner les bases neurophysiologiques de cette insouciance envers les méfaits de la cigarette chez les fumeurs. En utilisant l'imagerie cérébrale fonctionnelle, l'objectif de cette étude était: d’examiner la réponse neurophysiologique des fumeurs chroniques à des images qui illustrent les effets négatifs de la cigarette (campagne anti-tabac); d’examiner le caractère affectif de cette réactivité utilisant des conditions contrôles (c.-à-d., images aversives non-liées au tabac et appétitives liées au tabac); d'examiner la connectivité fonctionnelle durant cette tâche entre les systèmes affectifs et exécutifs (une interaction qui peut favoriser ou entraver l'impact des évènements aversifs). Méthodes: 30 fumeurs chroniques ont passé une session de neuroimagerie durant laquelle ils devaient regarder des images appétitives et aversives de cigarettes, des images aversives non-reliées au tabac et des images neutres. Résultats: Les images aversives liés au tabagisme suscitent une plus grande activation dans le cortex médial préfrontal, l'amygdale, le gyrus frontal inférieur et le cortex orbitofrontal latéral en comparaison avec les images neutres, mais une moins grande activation dans des structures médiaux / sous-corticales comparé aux images aversives non-reliés et images appétitives reliées aux tabac. L’activité du système exécutif présente une connectivité fonctionnelle négative avec le système affectif lorsque les images aversives sont liées au tabac, mais pas quand elles ne le sont pas. Conclusions: Le modèle d'activation du cerveau observé suggère qu’il y a un biais dans la réactivité des fumeurs chroniques lorsqu’ils observent des représentations négatives de la consommation du tabac. L’activité du système exécutif cérébral semble promouvoir chez les fumeurs une baisse d’activité dans des régions impliquées dans la genèse d’une réponse physiologique affective; il s’agit d’un mécanisme qui permettrait de réduire l’impact persuasif de ces représentations des méfaits de la cigarette sur la consommation des fumeurs. / Background: Studies have shown that appetitive smoking-related stimuli trigger important cravings in smokers which promote the maintenance of smoking behavior. Neuroimaging studies have been valuable in elucidating the mechanisms underlying this clinical feature. However, another important but under-explored feature of tobacco dependence is the inability for aversive smoking-related stimuli, such as anti-smoking campaigns, to influence this craving and smoking response. Using functional magnetic resonance imaging, the goal of this study was three-fold: to examine the neurobiological response of chronic smokers when processing aversive smoking-related cues; to further characterize this response using control conditions (i.e., aversive nonsmoking-related, appetitive smoking-related cues); to examine the pattern of functional connectivity during this task between executive and affective systems that may interact in ways that promote or hinder the impact of aversive events. Methods: Thirty chronic smokers passively viewed aversive smoking-related, aversive nonsmoking-related, appetitive smoking-related and neutral images presented in a block design while being scanned. Results: Aversive smoking-related stimuli elicited significantly greater activation in the medial prefrontal cortex, amygdala, inferior frontal gyrus and lateral orbitofrontal cortex than neutral stimuli. Aversive smoking-related stimuli elicited lower activation in medial/subcortical structures compared to the processing of aversive nonsmoking-related and appetitive smoking cues. Executive and affective systems are negatively associated when aversive cues are smoking-related, but not when nonsmoking-related. Conclusion: The brain activation pattern observed suggests that chronic smokers experience an aversive response when processing aversive smoking related stimuli, however we argue that the latter triggers a weaker negative emotional and driving response than the aversive nonsmoking-related and appetitive smoking-related cues respectively. Executive systems, activated during aversive smoking-related processing, may act to down-regulate activity in regions key to an affective and persuasive response; a mechanism that may reduce the extent to which “feeling bad” affects a change in behavior.

This diploma thesis deals with the problem of portfolio optimization in relation to the mean vector and the variance matrix of yields. The emphasis is put on Mar- kowitz model. In the thesis there are explored some possibilities of robustification based on the used parametric set. Beside the classic formulation of the task our focus is also devoted to the cases in which short sales are not allowed. The core of the thesis constitutes of a simulation study that models the impact of errors in the estimation of the input parameters of Markowitz model. It takes into account different types of risk aversions and different approaches to modelling parameter perturbations . Therefore it specifies the hypothesis of the dominating influence of the mean vector estimate which is valid only for a risk lover. 1