155 resultados para Random utility


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It has often been argued that there exists an underlying biological basis of utility functions. Taking this line of argument a step further in this paper, we have aimed to computationally demonstrate the biological basis of the Black-Scholes functional form as applied to classical option pricing and hedging theory. The evolutionary optimality of the classical Black-Scholes function has been computationally established by means of a haploid genetic algorithm model. The objective was to minimize the dynamic hedging error for a portfolio of assets that is built to replicate the payoff from a European multi-asset option. The functional form that is seen to evolve over successive generations which best attains this optimization objective is the classical Black-Scholes function extended to a multiasset scenario.

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We have first demonstrated that a random laser action generated by a hybrid film composed of a semiconducting organic polymer (SOP) and TiO2 nanoparticles can be used to detect 2,4,6-trinitrotoluene (TNT) vapors. The hybrid film was fabricated by spin-casting SOP solution dispersed with nanosized TiO2 particles on quartz glass. The SOP in the hybrid film functioned as both the gain medium and the sensory transducer. A random lasing action was observed with a certain pump power when the size (diameter of 50 nm) and concentration (8.9 - 1012/cm3) of TiO2 nanoparticles were optimized. Measurements of fluorescence quenching behavior of the hybrid film in TNT vapor atmosphere (10 ppb) showed that attenuated lasing in optically pumped hybrid film displayed a sensitivity to vapors of explosives more than 20 times higher than was observed from spontaneous emission. This phenomenon has been explained with the four-level laser model. Since the sensory transducer used in the hybrid polymer/nanoparticles system could be replaced by other functional materials, the concept developed could be extended to more general domains of chemical or environment detection.

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Glutathione is an endogenous antioxidant and has a ubiquitous role in many of the body’s defences. Treatment with N -acetylcysteine (NAC) has been shown to increase levels of glutathione. NAC has been proposed as a treatment for several illnesses. Objectives : The efficacy and tolerability of NAC was examined across a range of conditions to evaluate the evidence supporting the use of NAC for each indication. Methods : A literature search was conducted using PubMed. Information was also collected from other online sources including the websites of the Therapeutic Goods Administration of Australia and the FDA. Results : Reports ranged from case studies to clinical trials. There is strong evidence to support the use of NAC for the treatment of paracetamol overdose and emerging evidence suggesting it has utility in psychiatric disorders, particularly schizophrenia and bipolar disorder. NAC is safe and well tolerated when administered orally but has documented risks with intravenous administration.

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Antidepressant monotherapy is a first-line treatment for depression; however, not all sufferers will adequately respond to treatment. When treating a patient with treatment-resistant depression, the clinician needs to consider all factors which may contribute to an inadequate response to an antidepressant. These include accuracy of diagnosis and medication adherence, as well as the patient’s personality, lifestyle, life events and social circumstances. If it is determined that treatment resistance is due to failure of efficacy of antidepressant monotherapy, then an augmentation strategy using an atypical antipsychotic may be considered. Treatment using olanzapine/fluoxetine combination (OFC) is one of many options. Four randomized, acute-phase trials have suggested OFC is useful for reducing Montgomery–Åsberg Depression Rating Scale scores after inadequate response to antidepressant monotherapy. OFC has been useful at doses of olanzapine/fluoxetine 6/25, 6/50, 12/25 and 12/50 mg/day, with 1/5 mg/day suggested to be an ineffective dose. Treatment with OFC has been associated with some side effects, including weight gain and the metabolic syndrome, somnolence, dry mouth, increased appetite and headache. Treatment decisions therefore need to be made to balance the risks and benefits.

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Objective. Comorbid mental illness amongst methadone maintenance therapy clients may be common and screening may be warranted. The Mood Disorders Questionnaire (MDQ) is a screening tool for bipolar disorder that has been validated in other treatment settings. Its utility for patients with substance use disorders is assessed in this study.

Methods. Clients of a methadone maintenance program were invited to complete the MDQ when they attended a public Drug and Alcohol Service for their regular scheduled appointments. Information about their history of substance use was also collected.

Results. Eighty clients (43 females, 37 males) aged 35 8.0 years (mean SD) participated in the study. Seventy-four clients completed the MDQ of which 36 (48.6%) obtained a positive screen. A check of client fi les suggested that only three of the 74 participants had a current working diagnosis of bipolar disorder. These three participants had screened positive on the MDQ.

Conclusions. There was a high prevalence of manic symptoms reported by participants, suggesting that screening for bipolar disorder in this population may be warranted. However, there is a risk of false positives with the MDQ, as it does not clearly differentiate between symptoms of mania and drug intoxication.

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Background The quality of behaviour support plans (BSPs) can be an important influence on the quality of the support provided to people with disability who show challenging behaviours. The Behavior Support Plan Quality Evaluation Guide II (BSP-QE II) is one tool that may be useful in assessing the quality of behaviour support plans. It has previously been used to assess BSPs to support children in schools in the USA. In this preliminary study, we examined the utility of the BSP-QE II for assessing behaviour support plans designed for adults with an intellectual disability in community support services in Australia.

Method  Experienced practitioners were surveyed concerning the relevance of BSP-QE II components to the evaluation of BSPs in Australia, and an audit was conducted of randomly selected BSPs submitted as a statutory requirement to the Office of the Senior Practitioner.

Results  The BSP-QE II showed evidence of acceptable construct validity and interrater reliability. There was evidence of a need for substantial improvement in the quality of BSPs, consistent with previous findings conducted using other audit tools.

Conclusions The findings support the utility of the BSP-QE II, to inform and evaluate service planning in supporting adults with intellectual disability who show challenging behaviour.

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Introduction and Aims. Despite considerable success in tobacco control, many teenagers in Australia and other industrialised countries still smoke tobacco. There is mixed evidence on the relative influence of proximal social networks (parents/siblings/peers) on pre- and early-teen smoking, and no research has examined how these influences compare after accounting for school- and community-level effects.The aim of this study was to compare the relative influences of parents, siblings and peers, after accounting for school- and community-level variation in smoking.

Design and Methods.
A cross-sectional fixed and random effects model of smoking prevalence was used, with individuals (n = 7314) nested within schools (n = 231) nested within communities (n = 30). Grade 6 and 8 students (modal ages 11 and 13 years) completed an on-line survey. Key variables included parent/sibling/peer use. Controls included alcohol involvement, sensation seeking, pro-social beliefs, laws/norms about substance use and school commitment.

Results.There was significant variation in smoking at both the school and community levels, supporting the need for a multilevel model. Individual-level predictors accounted for much of the variance at higher levels. The strongest effects were for number of friends who smoke, sibling smoking and alcohol involvement. Smaller significant effects were found for parent smoking. At the community level, socioeconomic disadvantage was significant, but community-level variance in pro-social and drug-related laws/norms was not related to smoking.

Discussion and Conclusions. Cross-level interactions were generally non-significant. Early teenage smoking was best explained by sibling and peer smoking, and individual risks largely accounted for the substantial variation observed across schools and communities. In terms of future tobacco control, findings point to the utility of targeting families in disadvantaged communities.[Kelly AB, O'Flaherty M, Connor JP, Homel R, Toumbourou JW, Patton GC, Williams J. The influence of parents, siblings and peers on pre- and early-teen smoking: A multilevel model.

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Objective : To explore the relationship between overweight/obesity and utility in adolescents.

Methods : Data were collected from 2890 adolescents attending 13 secondary schools in the state of Victoria, Australia. The Assessment of Quality of Life 6-Dimension (AQoL-6D) questionnaire was used to measure individual utility. Adolescent's height and weight were measured and weight status categories assigned according to the World Health Organization adolescent growth standards. Multivariate linear regression analyses were undertaken for the whole population and subpopulations of boys and girls to estimate the mean differences in utility scores between 1) overweight and healthy weight and 2) obese and healthy weight adolescents, while controlling for demographic and socioeconomic status variables.

Results : The mean age of adolescents was 14.6 years, 56.2% were boys, 22.2% were overweight, and 9.4% were obese. The mean utility of healthy weight adolescents was 0.860. After adjustments, the overweight and obese groups reported significantly lower mean utility scores (differences: −0.018 and −0.059, respectively, relative to the healthy weight group). This can be interpreted as equivalent to a stated willingness to sacrifice 1.8% and 5.9% of a life in perfect health or 2.3% and 6.8% of a life at healthy weight. A significant utility difference associated with overweight was only experienced by girls (−0.039, P = 0.003). Both sexes experienced significant utility differences associated with obesity, but the magnitude was double for girls (−0.084, P < 0.001) relative to boys (−0.041, P = 0.022).

Conclusion : Utility is lower among overweight and more so among obese adolescents.

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The focus of this paper is on the community impact of education research, as conceived specifically within a changing context of research assessment in Australia, first mooted by the previous Federal Coalition (conservative) Government within a new Research Quality Framework (RQF), and now to be reworked by the Excellence in Research for Australia (ERA) initiated by the incoming Federal Labour (progressive) Government. Convinced that a penchant for the utility of research will not go away, irrespective of the political orientations of government, our interest is in exploring: the assumption that research, particularly in areas such as education, should have an impact in the community (as this was first defined within the RQF); the difficulties much education research (despite its “applied” characterisation) has in complying with this ideal; and what a community impact requirement means for the kinds of education research that will be privileged in the future. In particular, we are concerned about the potential narrowing of education research directed at or by community impact and what is lost in the process. One potential loss or weakening is in the positional autonomy of higher education to conduct independent education research.

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Automatic human action recognition has been a challenging issue in the field of machine vision. Some high-level features such as SIFT, although with promising performance for action recognition, are computationally complex to some extent. To deal with this problem, we construct the features based on the Distance Transform of body contours, which is relatively simple and computationally efficient, to represent human action in the video. After extracting the features from videos, we adopt the Conditional Random Field for modeling the temporal action sequences. The proposed method is tested with an available standard dataset. We also testify the robustness of our method on various realistic conditions, such as body occlusion or intersection.