A comparison of estimators of a common correlation coefficient

It is often of interest to test the hypothesis that all off-diagonal elements of the correlation matrix of a multivariate normal distribution are equal. If the hypothesis of equal correlation can be accepted, it then may be of interest to estimate the common correlation coefficient. In this paper, four estimators of the common correlation are compared in terms of bias, variance, mean squared error, adequacy of the normal approximation, and ease of calculation. The average sample correlation is seen to be comparable to the other estimators and is recommended here since it is the easiest to calculate. The estimators are compared using simulation.     

Bootstrap approaches for estimation and confidence intervals of long memory processes

In this work, we investigate an alternative bootstrap approach based on a result of Ramsey [F.L. Ramsey, Characterization of the partial autocorrelation function, Ann. Statist. 2 (1974), pp. 1296–1301] and on the Durbin–Levinson algorithm to obtain a surrogate series from linear Gaussian processes with long range dependence. We compare this bootstrap method with other existing procedures in a wide Monte Carlo experiment by estimating, parametrically and semi-parametrically, the memory parameter d. We consider Gaussian and non-Gaussian processes to prove the robustness of the method to deviations from normality. The approach is also useful to estimate confidence intervals for the memory parameter d by improving the coverage level of the interval.     

Autoregressiv model identification for multivariate time series

A procedure is developed for the identification of autoregressive models for stationary invertible multivariate Gaussian time series. Model selection is based on either the AIC information criterion or on a statistic called CVR, cross-validatory residual sum of squares. An example is given to show that the forecasts generated by these models compare favorably with those generated by other common time series modeling techniques.     

新时期高校图书馆馆员职业道德初探

新时期高校图书馆馆员职业道德的内容应包括热爱本职工作,严守规章制度,爱护馆藏文献,履行职业职能,真诚团结协作,不断努力学习等.加强高校图书馆馆员职业道德建设要通过正确的途径.     

Supply vessel planning under cost,environment and robustness considerations

Offshore oil and gas installations need reliable cargo deliveries. The vessels supplying these installations on a periodic basis are expensive and constitute a source of emissions of greenhouse gases. Incorporating vessel speed optimization into the supply vessel planning process may significantly reduce fuel consumption and hence emissions. In addition, speed optimization may yield cost reductions if the number of vessels used does not increase. A main uncertainty factor, especially in the winter season, is the weather conditions which impact sailing and service times. Cost minimization and the application of speed optimization strategies may have implications on the robustness of weekly supply vessel schedules since idle times in the schedules are reduced. We develop a simulation-optimization based methodology that considers costs, emissions and robustness in the generation of weekly supply vessel schedules. Results of analyses conducted on real instances show that robustness requirements may yield both increased emissions and costs in the winter season. However, depending on instance characteristics, different degrees of robustness can be incorporated with both costs and emissions reductions through speed optimization.     

《北里志》作者和创作考述

《北里志》是一部描写唐代大中年间长安士子狭邪生活的实录式笔记小说，作者孙棨。《唐摭言》和《唐才子传》误将作者记为赵光远的原因，既与赵光远的家庭出身及骄侈生活有关，又与赵光远狭邪香艳的文风相连。孙棨创作《北里志》，一方面受到晚唐笔记小说创作繁荣的影响，另一方面是想通过叙述艳情故事来垂戒后世。从《北里志》的实际流传情况来看，此书却实开后世艳情小说之端。     

From Bottom of the Barrel to Cream of the Crop: Sequential Screening With Positive Selection

In a number of interesting environments, dynamic screening involves positive selection: in contrast with Coasian dynamics, only the most motivated remain over time. The paper provides conditions under which the principal's commitment optimum is time consistent and uses this result to derive testable predictions under permanent or transient shocks. It also identifies environments in which time consistency does not hold despite positive selection, and yet simple equilibrium characterizations can be obtained.     

90后大学生思想行为特点与教育对策刍议

90后大学生成长于改革开放、经济社会和信息化迅猛发展,结构调整和社会急剧转型时期,价值观念、人际交往、消费方式都发生了巨大的变化,90后身上有着鲜明的时代特点,给高校的教育带来了极大的挑战。坚持以社会主义核心价值观为引领,把握大学生发展大方向;坚持显性教育与隐性教育的有机结合,营造潜移默化的教育氛围;坚持以人为本的教育理念,重视大学生的主体地位和判断能力;坚持以社会实践活动为载体,培养大学生社会责任感和团队合作精神,方能促进大学生成长成才。     

限量促销决策的情感机制——预期和预支情绪的视角

限量促销引发的是一种带有明显时间压力的决策情境。稀缺信息会引发预支情绪,限量品价值会引发预期情绪。预支情绪作为对未来进行展望而体验到的即时情感,有高兴和焦虑两种正负面情感。预期情绪作为人们想象经历确定结果后会有怎样的感受,有预期愉悦和害怕后悔两种正负面情感。在限量促销决策中,二者存在交互作用的可能性。此外,预支与预期情绪中的负面情感通常在临近促销时点时占优,而正面情感则在消息发布时占优。     

直面死亡：舍勒和海德格尔的不同选择

舍勒和海德格尔都放弃了死亡的经验性观点,认为死亡是自我生命的本质组成部分,不过,舍勒把死亡归属于意识的直观确定性,而海德格尔把其归属于此在的存在。二者都把死亡奠基在不同客观时间的现象学时间,不过在舍勒那里是内在时间意识,在海德格尔是更加复杂的时间性。二者都区分了本真的死亡观和非本真的死亡观,不过,对非本真性死亡观的批判在舍勒那里体现为对现代欧洲人的批评,在海德格尔那里体现为对常人的批评。