Patterns of alcohol use and marijuana use among students at 2- and 4-year institutions

Objective: The objective of this study was to understand substance use patterns of alcohol, marijuana, and simultaneous alcohol and marijuana (SAM) use among 2- and 4-year college students. Participants: Participants were 526 young adults aged 18–23 (n?=?355 4-year students; n?=?171 2-year students) recruited from February 2015 to January 2016 who were participating in a larger longitudinal study. Methods: Latent class analysis (LCA) was used to identify past-month classes of alcohol, marijuana, and SAM use. Results: Among both 2- and 4-year students, a four-class solution yielded the best-fitting model, with 2-year classes tending to include greater marijuana use and less alcohol use and 4-year classes tending to include heavy alcohol use. Demographic characteristics were largely similar across classes. Conclusions: Classes of alcohol, marijuana, and SAM use differed by education status. Screening and prevention efforts for 4-year students may need to be tailored for the needs of 2-year students.     

关于科学发现机器的研究

本文阐述了科学发现的两个判据,在知识存贮有劣性原理的基础上,提出了知识存贮不完全性原理,指出存在一类逻辑上具有非放大性,但认识论上具有放大性的演绎发现机器。在休谟问题逻辑学范围内不可解原理的基础上,论证了不存在通用的归纳发现机器,但建立局部合理的、有效的、完备的归纳发现机器是可行的。最后,本文描述了科学发现机器的结构,并在文献的基础上,描述了一种同时具有发生与评价功能的归纳发现机器并论证了它的合理性。     

W18Cr4V钢制造齿轮铣刀的热处理工艺

首先介绍W18Cr4V钢所含合金元素及其主要作用。随后重点分析W18Cr4V高速钢制造盘形齿轮铣刀的热处理工艺。掌握高速钢的热处理工艺方法,对于提高刀具的耐用度及加工质量具有现实意义。采用不同的热处理工艺参数,能得到不同的性能,同时也可满足不同工作条件和性能要求以及应用场合。     

艾滋病疗法的评价及疗效的预测

根据美国艾滋病医疗实验机构ACTG提供的两组数据,利用二次拟合预测了持续使用这四种艾滋病疗法的效果,并对这些疗法做出了一定的评价。     

“狂飙突进”时代的偏激——对五四作家心理状态的审视与反思

五四作家普遍表现出偏激情绪 ,其心理根源于作家们严重的焦虑和孤独与强烈的叛逆。而作家们的这种心理又是当时社会现实与作家个人经历、天赋禀性的产物。作家们的偏激情绪产生了激进的思想和激烈的言论 ,一方面以其狂飙突进的气势猛烈攻击封建传统与旧文化 ,另一方面由于潜在的农民文化心理的作用而不可避免地留下不少缺憾。同时 ,这种偏激情绪在文学创作中也产生了一定的影响     

Electronic payment mechanisms in social security: Extending the reach of benefit and contribution transactions

More often than not, the existing modes of contribution collection and benefit payment of social security organizations are adapted to the collective arrangements that characterize employer‐employee relationships. Extending coverage to individuals in difficult‐to‐reach groups, however, may require new modalities of service that can cope with many separate, secure transactions rather than a few bulk data transfers between organizations. Recent developments in electronic payment show its wide applicability in enabling huge volumes of such individual transactions. It is in this light that the article explores the potentials of this technology and identifies possible arrangements through which electronic payments could surmount barriers that stand in the way of covering difficult‐to‐reach groups. The high level of mobile phone penetration on a global scale augurs well for using e‐payment mechanisms to collect social security contributions and to deliver social security benefits and services. A generic model is used to describe the requisite elements to implement electronic payments in social protection programmes. Based on empirical evidence of current social protection practices from around the world, five scenarios are presented to describe possible configurations for electronic payment, from the simplest to the most sophisticated. The broader objective is to contribute in a practical manner to the international commitment to extend social protection to all, as defined by the 2030 Sustainable Development Goals.     

Pension reforms in EU11 countries: An evaluation of post‐socialist pension policies

This article evaluates the pension policy pathways of the 11 former state socialist nations that have joined the European Union since 2004. Focusing primarily on the post‐2004 period, the analysis discusses the most important measurable outcomes of these countries’ pension reforms, in terms of poverty alleviation, pension adequacy and fiscal sustainability. Going beyond the quantifiable concepts, we also investigate the quality of the 11 countries’ pension systems in terms of equity as well as efficiency, emphasizing the less conspicuous design errors present in these systems. Although these errors have received little attention to date, they may harm pension schemes along several dimensions, including their fiscal sustainability.     

Une jeunesse stigmatisée: l'influence du chômage précoce sur le chômage ultérieur

Le chômage rencontré au début du parcours professionnel favorise‐t‐il le chômage ultérieur? Pour le savoir, les auteurs suivent la trajectoire de quelque 700 000 actifs allemands sur une période de vingt‐quatre ans en utilisant des données administratives appariées employeurs‐salariés. Grâce à la méthode des variables instrumentales (l'instrument étant ici la fermeture de l'entreprise), ils font apparaître des séquelles durables du chômage précoce, chaque nouvelle journée chômée pendant les huit premières années de vie active augmentant d'une demi‐journée en moyenne le chômage des seize années suivantes. Selon des régressions quantiles, le caractère prolongé et répété des épisodes de chômage initial renforce sensiblement cet «effet cicatrice».     

引入整合风险的4PL模式下供应链资源整合优化

在对4PL模式下供应链资源整合运作特征及整合中主导因素及其关系进行简要描述的基础上,围绕对整合决策具有重要影响作用的整合风险进行了分析;提出了引入整合风险的资源整合决策模式,建立了4PL模式下供应链资源整合决策的拓展多目标优化数学模型,搭建了改进的蚁群寻优算法实现该整合决策优化过程的求解。最后通过算例验证了优化过程及算法的有效性与可行性。整合决策优化模型及算法突出体现了4PL的运作优势,突出了从战略高度及系统性角度对供应链整合风险的把握,同时实现了资源整合优化多目标之间的权衡。     

Convexity-based clustering criteria: theory,algorithms, and applications in statistics

This paper deals with the construction of optimum partitions of for a clustering criterion which is based on a convex function of the class centroids as a generalization of the classical SSQ clustering criterion for n data points. We formulate a dual optimality problem involving two sets of variables and derive a maximum-support-plane (MSP) algorithm for constructing a (sub-)optimum partition as a generalized k-means algorithm. We present various modifications of the basic criterion and describe the corresponding MSP algorithm. It is shown that the method can also be used for solving optimality problems in classical statistics (maximizing Csiszárs -divergence) and for simultaneous classification of the rows and columns of a contingency table.