904 resultados para 239903 Risk Theory


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A large body of empirical research shows that psychosocial risk factors (PSRFs) such as low socio-economic status, social isolation, stress, type-D personality, depression and anxiety increase the risk of incident coronary heart disease (CHD) and also contribute to poorer health-related quality of life (HRQoL) and prognosis in patients with established CHD. PSRFs may also act as barriers to lifestyle changes and treatment adherence and may moderate the effects of cardiac rehabilitation (CR). Furthermore, there appears to be a bidirectional interaction between PSRFs and the cardiovascular system. Stress, anxiety and depression affect the cardiovascular system through immune, neuroendocrine and behavioural pathways. In turn, CHD and its associated treatments may lead to distress in patients, including anxiety and depression. In clinical practice, PSRFs can be assessed with single-item screening questions, standardised questionnaires, or structured clinical interviews. Psychotherapy and medication can be considered to alleviate any PSRF-related symptoms and to enhance HRQoL, but the evidence for a definite beneficial effect on cardiac endpoints is inconclusive. A multimodal behavioural intervention, integrating counselling for PSRFs and coping with illness should be included within comprehensive CR. Patients with clinically significant symptoms of distress should be referred for psychological counselling or psychologically focused interventions and/or psychopharmacological treatment. To conclude, the success of CR may critically depend on the interdependence of the body and mind and this interaction needs to be reflected through the assessment and management of PSRFs in line with robust scientific evidence, by trained staff, integrated within the core CR team.

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Risk-taking tendencies and environmental opportunities to commit crime are two key features in understanding criminal behavior. Upon release from prison, ex-prisoners have a much greater opportunity to engage in risky activity and to commit criminal acts. We hypothesized that ex-prisoners would exhibit greater risk-taking tendencies compared to prisoners who have fewer opportunities to engage in risky activity and who are monitored constantly by prison authorities. Using cumulative prospect theory to compare the risky choices of prisoners and ex-prisoners our study revealed that ex-prisoners who were within 16 weeks of their prison release made riskier choices than prisoners. Our data indicate that previous studies comparing prisoners behind bars with nonoffenders may have underestimated the risk-taking tendencies of offenders. The present findings emphasize the central role played by risk-taking attitudes in criminal offending and highlight a need to examine offenders after release from prison.

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The aim of this paper is to link empirical findings concerning environmental inequalities with different normative yard-sticks for assessing whether these inequalities should be deemed unjust, or not. We argue that such an inquiry must necessarily take into account some caveats regarding both empirical research and normative theory. We suggest that empirical results must be contextualised by establishing geographies of risk. As a normative yard-stick we propose a moderately demanding social-egalitarian account of justice and democratic citizenship, which we take to be best suited to identify unjust as well as legitimate instances of socio-environmental inequality.

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This paper examines the relationship between concepts of MNE bargaining power and broader concepts of political power. It notes that the analysis of MNE bargaining power presents a number of puzzles from the perspective of political theory. These puzzles arise, in part, from the fact that the overlap between traditional concepts of MNE bargaining power and broader concepts of political power is only a partial one. Despite these problems, it is suggested that political- theory-based approaches can add realism to our understanding of bargaining power.

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Polygenic risk scores have shown great promise in predicting complex disease risk and will become more accurate as training sample sizes increase. The standard approach for calculating risk scores involves linkage disequilibrium (LD)-based marker pruning and applying a p value threshold to association statistics, but this discards information and can reduce predictive accuracy. We introduce LDpred, a method that infers the posterior mean effect size of each marker by using a prior on effect sizes and LD information from an external reference panel. Theory and simulations show that LDpred outperforms the approach of pruning followed by thresholding, particularly at large sample sizes. Accordingly, predicted R(2) increased from 20.1% to 25.3% in a large schizophrenia dataset and from 9.8% to 12.0% in a large multiple sclerosis dataset. A similar relative improvement in accuracy was observed for three additional large disease datasets and for non-European schizophrenia samples. The advantage of LDpred over existing methods will grow as sample sizes increase.

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This paper examines the role of higher-order moments in portfolio choice within an expected-utility framework. We consider two-, three-, four- and five-parameter density functions for portfolio returns and derive exact conditions under which investors would all be optimally plungers rather than diversifiers. Through comparative statics we show the importance of higher-order risk preference properties, such as riskiness, prudence and temperance, in determining plunging behaviour. Empirical estimates for the S&P500 provide evidence for the optimality of diversification.

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The present paper studies the probability of ruin of an insurer, if excess of loss reinsurance with reinstatements is applied. In the setting of the classical Cramer-Lundberg risk model, piecewise deterministic Markov processes are used to describe the free surplus process in this more general situation. It is shown that the finite-time ruin probability is both the solution of a partial integro-differential equation and the fixed point of a contractive integral operator. We exploit the latter representation to develop and implement a recursive algorithm for numerical approximation of the ruin probability that involves high-dimensional integration. Furthermore we study the behavior of the finite-time ruin probability under various levels of initial surplus and security loadings and compare the efficiency of the numerical algorithm with the computational alternative of stochastic simulation of the risk process. (C) 2011 Elsevier Inc. All rights reserved.

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This study examined students considered at risk of non-completion of their Ontario Secondary School Diploma and aimed to offer insight into the questions, "What factors currently lead to school disconnect" and "How can these factors be addressed?" Eight students currently enrolled in an alternative learning environment participated in the study. Each was asked to take part in two, digitally recorded interviews that were subsequently transcribed by the researcher. The data were then coded and analysed according to specific themes: obstacles, empowerment, goals, views about success, opinions of school, and power of the teacher. From these themes, three broad focus areas emerged that were used to keep the data analysis focused: worldview, school effects, and self-image. Variances between the data collected and ideas presented in the current literature were highlighted as a reminder that when dealing with a human population, we cannot rely on textbook definitions and theory alone.

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A cardiovascular disease risk factor reduction program was implemented in the Niagara region. To gain an understanding of this program from the participants ' perspective, 10 participants of the program were interviewed to document their perceptions of what they learned in the program, their perceptions of their behaviour change and their perceptions of factors that facilitated or impeded any behaviour change. The learning style inventory and PET test were also given to the participants to further understand their perceptions. Findings unique to this study highlighted aspects of the andragogical model, self-directed learning theory, learning style preference and psychological type that were prominent in the participants' comments and perspectives. Implications for practice, theory development and further research are suggested.

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The purpose of this project was to discern the inherent tension present in narratives told by adolescents with a visual impairment as they attempted to make sense of their experiences, specifically those surrounding risk. Mediated action, based on the foundational work of Vygotsky and Bakhtin, was used as both a theoretical and methodological approach; it is the theory that there are two components that constitute any human action: the "agent," or the person who is doing the acting, and the "mediational means" that he or she is using to accomplish the action in question. Tension ensues as neither is able to fully explain human behaviour. Ten adolescents with a visual impairment participated in a narrative interview, revealing numerous counter-narratives surrounding risk-taking, including "experimentation undertaken using good judgment." Participants offered examples of how they engaged, appropriated, resisted and transformed the dominant narratives of disability and adolescence in their identity formation.

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Youth have been found to engage in various risk-taking behaviours at higher rates than any other age group. However, there is a lack of research on the division between adaptive and maladaptive risk behaviours among adolescents and emerging adults. Adaptive risk-taking behaviours may present youth with ways to successfully partake in the risk behaviours that they are naturally inclined to engage in. The relationship between activity engagement and positive youth development has been extensively studied and cited as a way to expose youth to positive experiences and promote successful development. However, the relationship between activity engagement and risk behaviours among youth has yetto be studied in depth. This study investigated the potential relationship between various adaptive and maladaptive risk behaviours and activity engagement among youth, through an indirect link through five mediator variables. These potential mediators represented the three systems in Jessor's Problem Behaviour Theory. Participants included 276 youth (M = 19.06 years, SD = 1.60, 89.1 % female) from Brock University. Results revealed that activity engagement significantly predicted greater adaptive social risk behaviours among youth. However, there was no mediating effect through the problem behaviour systems. Correlations revealed that being male was associated with more maladaptive risk behaviours and fewer adaptive risk behaviours than females. Additionally, behavioural engagement specifically related to less maladaptive physical health risks and psychological engagement related to greater adaptive social risks. Overall, these findings suggest that activity engagement may be differentially related to the various types of risk-taking and gender associations may exist between the various types and dimensions of risk behaviours, but future work is needed to understand the variables that may explain such relationships.

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This survey presents within a single model three theories of decentralization of decision-making within organizations based on private information and incentives. Renegotiation, collusion, and limits on communication are three sufficient conditions for decentralization to be optimal.

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The attached file is created with Scientific Workplace Latex

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Thèse numérisée par la Division de la gestion de documents et des archives de l'Université de Montréal

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Nous y introduisons une nouvelle classe de distributions bivariées de type Marshall-Olkin, la distribution Erlang bivariée. La transformée de Laplace, les moments et les densités conditionnelles y sont obtenus. Les applications potentielles en assurance-vie et en finance sont prises en considération. Les estimateurs du maximum de vraisemblance des paramètres sont calculés par l'algorithme Espérance-Maximisation. Ensuite, notre projet de recherche est consacré à l'étude des processus de risque multivariés, qui peuvent être utiles dans l'étude des problèmes de la ruine des compagnies d'assurance avec des classes dépendantes. Nous appliquons les résultats de la théorie des processus de Markov déterministes par morceaux afin d'obtenir les martingales exponentielles, nécessaires pour établir des bornes supérieures calculables pour la probabilité de ruine, dont les expressions sont intraitables.