The Economic Assimilation of African Immigrants in the United States

This article examines the puzzle that the earnings of African immigrants do not match their high qualifications in terms of educational attainment. We apply cohort analysis to compare the economic assimilation patterns of black African immigrants with that of black non‐African immigrants. We find results that are consistent with the idea that the lower earnings of African immigrants are due to greater difficulty with skill transferability. Africans face substantially lower earnings at entry than black natives and black non‐African immigrants, although they close a substantial part of the initial earnings gap over time. Moreover, the earnings gap at entry has narrowed for recent cohorts; and Africans who migrate during childhood and those with no college education face no disadvantage. We also find similar patterns of assimilation in labour supply and participation in welfare programmes, which indicate that Africans face greater challenges at entry but assimilate at a faster rate.     

案例行动学习法——效率与效果的兼顾

案例教学法、行动学习法等主流商科情境教学模式虽在国内商学院中得到广泛的应用,但囿于使用过程中的资源限制、实施变形及方法本身的局限性,导致教学双方的反馈尚不尽如人意。本文介绍了一种全新的商科情境教学方法--"案例行动学习法"。论文应用建构主义理论探讨了"案例行动学习法"的基本原理,研究了该种方法的能力建构机理,分析了其成为工商管理主流情境教学方法的效率与效果的平衡机理,介绍了前期应用的效果。研究结果表明,"案例行动学习法"作为一种全新的工商管理情境教学方法,能够将案例教学与行动学习两种方法的优点有机结合在一起,具备在全国范围内推广的条件。     

Does Remittance Outflow Stimulate or Retard Economic Growth?

This article evaluates the association between remittance outflow (RMO) and economic growth in the Gulf Cooperation Council (GCC) countries. The results of this evaluation indicate that RMO Granger creates gross domestic product (GDP) per capita in three countries, namely, Bahrain, Oman and Saudi Arabia. Similarly, the results for causality from GDP per capita to RMO are significant for four countries, namely, Bahrain, Kuwait, Qatar, and Saudi Arabia. The findings differ from those of the household consumption model, stating that higher RMO will decrease economic activity. GDP per capita is the main determinant of RMO, suggesting that economic growth promises and encourages continuous RMO and vice versa. The adverse impact of RMO can be minimized by encouraging the local population to be productive in the private sector, as local productivity will reduce the huge influx of foreign workers and provide valuable local investment opportunities to lessen the amount being remitted.     

辽东第一山

大约4亿年前,千山山脉一带是一片海洋,到古生代末期开始形成陆地.经过漫长的地壳变化,到一千万年前,初步形成了千山地貌的基本轮廓.如今,它与长白山山脉相连,绵亘数百里,是整个辽东半岛的脊梁,辽河、鸭绿江分水岭.其中最峻秀的千朵莲花峰就矗立在鞍山城东南.清代文人姚元之有诗云:明霞为饰玉为容,山到辽阳峦嶂重.     

BAN网络节点低功耗MAC协议的设计

本文针对IEEE802.15.6标准中的MAC层协议采用固定保护时间弥补时钟漂移而造成能量浪费这一问题研究并实现一种低功耗的适宜BAN网络的MAC协议。该协议依据超帧结构的模式构建了一种新的MAC帧结构模型,并结合时间补偿算法对帧结构中的保护时间进行自适应调整,最后使用OPNET14.5仿真两种MAC协议。结果表明,本文研究的基于自适应时间补偿帧结构的MAC协议相对于固定的保护时间IEEE802.15.6的MAC协议而言,降低了终端节点能耗以及延长了网络的生存周期。     

普通高等学校继续教育综合改革发展趋势及应对策略--以成都理工大学为例

高等继续教育在高等教育中的比重逐年下降，发展空间受到挤压。针对当前高等继续教育在教育形式、教育机制、教学模式等方面遇到的问题，各高校应调整继续教育办学形式，适时开展网络远程教育，拓展办学范围，加快校外教学站点整合，积极开展优质数字资源建设，以期促进高等继续教育快速发展。     

Modelling hierarchical clustered censored data with the hierarchical Kendall copula

This article proposes a new model for right‐censored survival data with multi‐level clustering based on the hierarchical Kendall copula model of Brechmann (2014) with Archimedean clusters. This model accommodates clusters of unequal size and multiple clustering levels, without imposing any structural conditions on the parameters or on the copulas used at various levels of the hierarchy. A step‐wise estimation procedure is proposed and shown to yield consistent and asymptotically Gaussian estimates under mild regularity conditions. The model fitting is based on multiple imputation, given that the censoring rate increases with the level of the hierarchy. To check the model assumption of Archimedean dependence, a goodness‐of test is developed. The finite‐sample performance of the proposed estimators and of the goodness‐of‐fit test is investigated through simulations. The new model is applied to data from the study of chronic granulomatous disease. The Canadian Journal of Statistics 47: 182–203; 2019 © 2019 Statistical Society of Canada     

发动机环组漏气分析

在对活塞－气缸－活塞环间隙内的气体流动及环的轴向运动进程理论分析与数值计算的基础上,分析了环与活塞结构参数,发动机运行参数诸因素对环组漏气量的影响,为验证模型和正确性,将实测漏气数据与计算结果进行了对比,两者具有很好的一致性。