Bayesian penalized B-spline estimation approach for epidemic models

Ordinary differential equations (ODEs) are normally used to model dynamic processes in applied sciences such as biology, engineering, physics, and many other areas. In these models, the parameters are usually unknown, and thus they are often specified artificially or empirically. Alternatively, a feasible method is to estimate the parameters based on observed data. In this study, we propose a Bayesian penalized B-spline approach to estimate the parameters and initial values for ODEs used in epidemiology. We evaluated the efficiency of the proposed method based on simulations using the Markov chain Monte Carlo algorithm for the Kermack–McKendrick model. The proposed approach is also illustrated based on a real application to the transmission dynamics of hepatitis C virus in mainland China.     

苏格兰独立问题的历史与未来

苏格兰自1707年并入英联合王国后,要求独立的呼声始终未断,2007年苏格兰民族党成为执政党后,独立呼声愈演愈烈。"苏格兰的未来将由苏格兰人民来决定",2014年9月18日苏格兰进行独立公投。从历史沿革、政治权势博弈两个方面入手可把握苏格兰独立问题的整体脉络。将英国政治制度中的务实传统与当前多重利益因素综合考虑,可诠释苏格兰独立问题的产生原因、英国政府同意公投的实用主义倾向。     

道德治理的三重向度——斯密视角及其当下启示

道德治理概念的提出,既是直面当前道德问题的一种理论自觉,也成为改善当下社会道德状况、提升道德水平的现实课题。而亚当·斯密对导致道德情操败坏的原因的分析,以及对惩罚与正义、欲望与良知、报偿与信仰的理论叙述,对当下社会认识各种败德现象的成因以及就解决各种道德问题所能谋求的治理之道,提供了可资借鉴的理论资源和实践参照。     

Sensitivity Analysis Using Risk Measures

In a quantitative model with uncertain inputs, the uncertainty of the output can be summarized by a risk measure. We propose a sensitivity analysis method based on derivatives of the output risk measure, in the direction of model inputs. This produces a global sensitivity measure, explicitly linking sensitivity and uncertainty analyses. We focus on the case of distortion risk measures, defined as weighted averages of output percentiles, and prove a representation of the sensitivity measure that can be evaluated on a Monte Carlo sample, as a weighted average of gradients over the input space. When the analytical model is unknown or hard to work with, nonparametric techniques are used for gradient estimation. This process is demonstrated through the example of a nonlinear insurance loss model. Furthermore, the proposed framework is extended in order to measure sensitivity to constant model parameters, uncertain statistical parameters, and random factors driving dependence between model inputs.     

Asymptotic theory for maximum likelihood estimates in reduced-rank multivariate generalized linear models

Reduced-rank regression is a dimensionality reduction method with many applications. The asymptotic theory for reduced rank estimators of parameter matrices in multivariate linear models has been studied extensively. In contrast, few theoretical results are available for reduced-rank multivariate generalized linear models. We develop M-estimation theory for concave criterion functions that are maximized over parameter spaces that are neither convex nor closed. These results are used to derive the consistency and asymptotic distribution of maximum likelihood estimators in reduced-rank multivariate generalized linear models, when the response and predictor vectors have a joint distribution. We illustrate our results in a real data classification problem with binary covariates.     

基于问题解决的全面质量管理

指出了车间主管的角色在于创设工作场所，发挥员工潜力。归纳了4种类型的问题解决方法：自我否定，别人过错，鸵鸟型，问题解决型，分析了强有力车间的概念。依据全面质量管理标准，将其与问题解决相联系，给出了全面质量管理的特征，阐明了两者之间的关系。     

Multinomial Selection in the Presence of Infinite Alternatives

We propose a new procedure for the multinomial selection problem to solve a real problem of any modern Air Force: the elaboration of better air-to-air tactics for Beyond Visual Range air-to-air combat that maximize its aircraft survival probability H(θ, ω), as well as enemy aircraft downing probability G(θ, ω). In this study, using a low-resolution simulator with generic parameters for the aircraft and missiles, we could increase an average success rate of 16.69% and 16.23% for H(θ, ω) and G(θ, ω), respectively, to an average success rate of 76.85% and 79.30%. We can assure with low probability of being wrong that the selected tactic has greater probability of yielding greater success rates in both H(θ, ω) and G(θ, ω) than any simulated tactic.     

Pathways and transitions of gamblers over two years

Moderate-risk and problem gamblers represent 1.4% and 0.4% of the Québec population, respectively. Research on gamblers’ trajectories has been hampered by methodological shortcomings leading to heterogeneous results. The present research was conducted in the Province of Québec with a representative sample of adult gamblers and aims to explore how gamblers change over time according to the severity of their gambling problems. Using a 2-year follow-up prospective design (3 waves), 179 gamblers selected from a representative survey were divided into the 4 PGSI (Problem Gambling Severity Index) categories. Beyond the decreasing trend in PGSI scores detected within the overall sample using a linear growth model, our analyses revealed that moderate-risk gamblers are heterogeneous in their composition and evolution, comprising stable moderate-risk, recent cases and former problem gamblers. Over three waves, one-third of moderate-risk gamblers improved, one-third remained stable and one-third became problem gamblers. The subgroups transitioning in and out of the moderate-risk category differed in terms of reported changes in gambling behaviours and consequences. Problem gamblers remain vulnerable over time, being at risk of experiencing chronic problems. Results highlight the necessity of subgroup-specific prevention programmes and treatment services that address both the non-linearity of risky gambling and the chronicity of problem gambling.     

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.     

基于盾构掘进参数的LVQ神经网络地层识别

以苏州4号线2标及2号线东延伸线5标地铁工程为背景，分析了盾构机的掘进参数：千斤顶推力、推进速度、刀盘扭矩、螺旋机转速和同步注浆量在不同地层条件下的变化规律。提出了基于盾构机掘进参数的学习向量量化（Learning Vector Quantization，LVQ）神经网络地层识别方法。建立了以盾构机五个掘进参数作为输入，地层特性编码为输出的数学模型，通过每种地层100组训练样本对模型进行训练，通过57步训练，训练样本误差控制在0.1以内，并用每种地层50组检验样本进行检验，地层总体识别率达到82.7%。