Changes in risky gambling prevalence among a New Zealand population cohort

Evidence suggests that problem gambling is an unstable state where gamblers move into and out of risk over time. This article looks at longitudinal changes in risky gambling and the factors associated with an increased risk (measured by the Problem Gambling Severity Index [PGSI]) in the current New Zealand context, which has experienced a doubling of the electronic gaming machine (EGM) market over the last two decades. Respondents from a nationally representative baseline sample (n = 2672) were recontacted two years later to assess changes in gambling behaviours. Among the 901 respondents reached at follow-up, average gambling risk increased over time, and the prevalence of those who had at least some level of gambling risk (i.e. low-risk or greater) more than doubled (from 4.7% to 12.4%). The majority (80.2%) of those who were at risk at follow-up had not been at risk at baseline. Multivariate linear regression analyses show that the predictors of low to moderate increased risk include Pacific ethnicity; high neighbourhood deprivation status; baseline frequent, continuous gambler type; baseline PGSI status; and playing EGMs. These findings highlight the need to develop theories of gambling addiction trajectories and to identify the earliest point along the trajectory where public health interventions should occur.     

“第三极文化”视野下的中国电影美学

第三极文化理论对中国电影美学建设具有启示意义,在第三极理论的视野下,对中国电影的美学渊源、美学精神、美学内涵进行重新观照,有助于解释或解答许多困惑性的问题,尤其对中国电影的民族化建设具有重要的启示价值.     

气藏水平井连续携液理论与实验

在气藏水平井中随着生产管柱倾斜角度的变化，井筒内液体的重力作用会发生改变，从而引起气液两相流型的变化。以产气为主的气井井筒内液体主要以液膜、液滴的形式出现，由此出现了液滴模型与液膜模型两种解释积液的理论。从这两种携液理论出发，考虑生产管柱倾斜角度的影响，对倾斜管内液滴、液膜进行受力分析，推导出了随管柱倾斜角度变化的连续携液临界流速的计算式，使之适用于水平井连续携液临界流量的计算。设计制作了水平气井连续携液实验装置并进行了实验研究，观测气藏水平井中气水两相运动与流型变化情况并测试其临界携液气量，结果表明，气藏水平井中水平井段的液体以液膜携带为主，但直井段中越接近井口，越以液滴携带为主，液滴模型也能适用于计算气藏水平井的连续携液临界流速。     

改进离散人工蜂群算法规划异形满版服饰图案切割路径

服饰图案切割路径规划是服饰图案自动切割技术的关键部分之一。文中用改进的离散人工蜂群算法实现了激 光切割系统对异形满版服饰图案的切割工艺路径规划优化。首先,把满版服饰图案激光切割路径规划转化为广义旅行 商问题求解,证明了路径规划转化成普通TSP问题比转化成第一类广义TSP问题更为有效,并给出了路径规划中“图案 始切割点”的优化选择方法。然后结合部分匹配交叉和启发式变异搜索方法的人工蜂群算法求解TSP问题,证明了与 A*算法及遗传算法相比,该方法更为优越。并且该方法已应用于激光切割机切割异形满版服饰图案路径规划的生产实 践,运行可靠,比未规划时的工艺路线平均提高效率33.7%。该方法提供了一种解决TSP问题的新方法,具有一定的理 论意义和价值     

Mixed-effects Models with Skewed Distributions for Time-varying Decay Rate in HIV Dynamics

After initiation of treatment, HIV viral load has multiphasic changes, which indicates that the viral decay rate is a time-varying process. Mixed-effects models with different time-varying decay rate functions have been proposed in literature. However, there are two unresolved critical issues: (i) it is not clear which model is more appropriate for practical use, and (ii) the model random errors are commonly assumed to follow a normal distribution, which may be unrealistic and can obscure important features of within- and among-subject variations. Because asymmetry of HIV viral load data is still noticeable even after transformation, it is important to use a more general distribution family that enables the unrealistic normal assumption to be relaxed. We developed skew-elliptical (SE) Bayesian mixed-effects models by considering the model random errors to have an SE distribution. We compared the performance among five SE models that have different time-varying decay rate functions. For each model, we also contrasted the performance under different model random error assumptions such as normal, Student-t, skew-normal, or skew-t distribution. Two AIDS clinical trial datasets were used to illustrate the proposed models and methods. The results indicate that the model with a time-varying viral decay rate that has two exponential components is preferred. Among the four distribution assumptions, the skew-t and skew-normal models provided better fitting to the data than normal or Student-t model, suggesting that it is important to assume a model with a skewed distribution in order to achieve reasonable results when the data exhibit skewness.     

Investigating impacts of complex sampling on latent growth curve modelling

We investigate the impacts of complex sampling on point and standard error estimates in latent growth curve modelling of survey data. Methodological issues are illustrated with empirical evidence from the analysis of longitudinal data on life satisfaction trajectories using data from the British Household Panel Survey, a national representative survey in Great Britain. A multi-process second-order latent growth curve model with conditional linear growth is used to study variation in the two perceived life satisfaction latent factors considered. The benefits of accounting for the complex survey design are considered, including obtaining unbiased both point and standard error estimates, and therefore correctly specified confidence intervals and statistical tests. We conclude that, even for the rather elaborated longitudinal data models that were considered, estimation procedures are affected by variance-inflating impacts of complex sampling.     

Goodness-of-fit tests of generalized linear mixed models for repeated ordinal responses

Categorical longitudinal data are frequently applied in a variety of fields, and are commonly fitted by generalized linear mixed models (GLMMs) and generalized estimating equations models. The cumulative logit is one of the useful link functions to deal with the problem involving repeated ordinal responses. To check the adequacy of the GLMMs with cumulative logit link function, two goodness-of-fit tests constructed by the unweighted sum of squared model residuals using numerical integration and bootstrap resampling technique are proposed. The empirical type I error rates and powers of the proposed tests are examined by simulation studies. The ordinal longitudinal studies are utilized to illustrate the application of the two proposed tests.     

小说的影像阐释及其意义解读

小说的影像阐释是当代影视剧生产的重要源泉,在视觉文化主导的今天,小说的影像阐释不仅使小说进入文字阅读和视听感知结合的“共读”时代,而且为影像作品提供了丰富的内容和形式。同时,小说的影像阐释已经对当代作家的小说书写、小说生成方式及小说传播形态产生了意义深远的影响。     

英国电影审查、分级制与其社会语境

中国电影不断走向世界的同时,国际电影也愈来愈深刻地影响中国电影市场,如何在全球化视野中推进中国电影业的发展,这就成为中国电影应对国际国内电影发展新挑战的关键所在,而重构中国电影审查与分级制度则是其中的重要环节之一。研究美国、英国、加拿大、澳大利亚等电影工业发达国家相对成熟发达的电影审查与分级制度及其历史性转型经验,不仅对于建立有中国特色的电影分级制度有着实际而又重要的借鉴作用,而且对于深入透视西方当代传媒制度也意义重大。     

Improving variance function estimation in semiparametric longitudinal data analysis

We propose an efficient and robust method for variance function estimation in semiparametric longitudinal data analysis. The method utilizes a local log‐linear approximation for the variance function and adopts a generalized estimating equation approach to account for within subject correlations. We show theoretically and empirically that our method outperforms estimators using working independence that ignores the correlations. The Canadian Journal of Statistics 39: 656–670; 2011. © 2011 Statistical Society of Canada