北京非首都功能疏解的思考与刍议——基于"新都市主义"的视角

从集聚的两面性切入"首都城市病"问题,反思疏解集聚的必要性.在回顾城市发展史和总结"新都市主义"理论体系的基础上,认为疏解北京非首都功能应先搞清北京集聚背后的功能因素.通过国际横向对比和国内纵向对比发现,北京存在核心首都功能不强,发展不够紧凑;非核心首都功能和非首都功能冗余,城市增长出现低效率化.因此,将"新都市主义"理论中国化,提出北京未来的疏解思路:TOD模式中国化.     

Likelihood procedure for testing changes in skew normal model with applications to stock returns

The skew normal distribution family is an attractive distribution family due to its mathematical tractability and inclusion of the normal distribution as the special case. It has wide applications in many applied fields such as finance, economics, and medical research. Such a distribution family has been studied extensively since it was introduced by Azzalini in 1985 Azzalini, A. (1985). A class of distributions which includes the normal ones. Scandinavian Journal of Statistics 12:171–178. [Google Scholar] for the first time. Yet, few work has been done on the study of change point problem related to this distribution family. In this article, we propose the likelihood ratio test (LRT) to detect changes in the parameters of the skew normal distribution associated with some asymptotic results of the test statistic. Simulations have been conducted under different scenarios to investigate the performance of the proposed method. Comparisons to some other existing method indicate the comparable power of the method in detecting changes in parameters of the skew normal distribution model. Applications on two real data: Brazilian and Tanzanian stock returns illustrate the detection procedure.     

An optimal online algorithm for the parallel-batch scheduling with job processing time compatibilities

We consider the online (over time) scheduling on a single unbounded parallel-batch machine with job processing time compatibilities to minimize makespan. In the problem, a constant \(\alpha >0\) is given in advance. Each job \(J_{j}\) has a normal processing time \(p_j\). Two jobs \(J_i\) and \(J_j\) are compatible if \(\max \{p_i, p_j\} \le (1+\alpha )\cdot \min \{p_i, p_j\}\). In the problem, mutually compatible jobs can form a batch being processed on the machine. The processing time of a batch is equal to the maximum normal processing time of the jobs in this batch. For this problem, we provide an optimal online algorithm with a competitive ratio of \(1+\beta _\alpha \), where \(\beta _\alpha \) is the positive root of the equation \((1+\alpha )x^{2}+\alpha x=1+\alpha \).     

Network domains in social networking sites: expectations,meanings, and social capital

This paper examines why the use of social networking sites (SNSs) leads to different results in cultivating bridging and bonding social capital for different groups of people. Based on in-depth interviews of 45 university students in Hong Kong, I find that Mainland Chinese students studying in Hong Kong actively use SNSs for seeking practical information about offline matters, and they obtain substantial enacted support from other Mainland students of the same university through SNS use. As a result, they accumulate both bridging and bonding social capital. Local Hong Kong students, however, use SNSs mainly for social information seeking and are only able to accrue limited bridging social capital through SNS use. Drawing on the theory of network domains, I argue that the different offline network structures in which students are located – namely, homogeneous and closed networks versus heterogeneous and open networks – explain this difference. Students with closed offline networks have defined expectations of online ties; they think of their online activities as practical and leading to real changes in their status among peers. Those with open networks have indefinite expectations of their online audience; thus, they interpret online activities differently, thinking of them as recreational, and they are playful in their online behaviour. These different outcomes of online activities consequently lead to diverse results in social capital accrual.     

国内外郊野公园规划案例比较及展望

郊野公园是优化城市空间格局、供人们游憩和健身的重要载体。通过对国内外有代表性的郊野公园规划案例进行归纳总结,利用比较研究的方法对其发展概况、主要活动项目、配套设施建设与相关规划条例等方面进行比较分析,并从选址特征、规划实施与运营管理情况3个方面总结我国郊野公园在规划与管理上的缺点与不足,在此基础上,对我国郊野公园今后的建设与管控模式进行展望。     

我国创业板市场的设立和风险投资退出机制

风险投资对于经济的增长尤其是高新技术的发展有非常重要的意义。而风险投资能够适时地成功退出,是其良好发展的关键。通过分析风险投资退出机制发现,我国新推出的创业板市场较低的上市条件．使风险投资更容易变现和退出。风险投资的不断发展,为创业板市场培育出优秀的上市资源。将创业板市场与风险投资退出机制结合,相辅相成,可以促进风险资金良性循环。     

试论健美操运动对大学生树立终身体育观的影响

高校体育作为学校体育教育的最高层次和最后环节,是学校体育与体育社会化的转折点和学与用的衔接点。因此对大学生来说终身体育教育是我国高校体育教育的重要课题之一。健美操运动不仅能全面锻炼身体的各个部位,更能培养大学生自觉运动的能力和习惯,从而影响他们,使之形成终身体育的观念。     

税费改革前后农村基础教育投入变化及其影响

税费改革是我国农村继土地革命、家庭联产承包责任制后的又一场深刻变革。它不仅给农村经济、社会带来巨大变化,而且直接影响到农村基础教育。文章从分析农村基础教育投入持续偏低导致农村基础教育薄弱入手,探讨了税费改革给农村基础教育投入带来的积极变化和消极影响,并在此基础上提出消除消极影响的对策建议。     

高维混合效应模型的双正则化分位回归方法研究

针对高维混合效应模型,本文提出了一种双正则化分位回归方法.通过对随机和固定效应系数同时实施L1正则化惩罚,一方面能够对重要解释变量进行挑选,另一方面能够消除个体随机波动带来的偏差.求解参数估计的交替迭代算法不仅破解了要同时确定两个调整参数的难题,而且算法速度快.模拟结果也表明该方法不仅对误差类型有很强的抗干扰能力,同时在模型有不同稀疏程度时均表现良好,尤其是对于解释变量多于样本的高维情况.为了方便在实际问题中选择最优正则化参数,本文还对两种参数选取标准进行了比较研究.最后利用新方法对一个教育方面的数据进行了实证演示,找出了在各个分位点处对学生成绩有影响的重要因素.     

Generalized empirical likelihood inference in partial linear regression model for longitudinal data

In this paper, empirical likelihood inference for longitudinal data within the framework of partial linear regression models are investigated. The proposed procedures take into consideration the correlation within groups without involving direct estimation of nuisance parameters in the correlation matrix. The empirical likelihood method is used to estimate the regression coefficients and the baseline function, and to construct confidence intervals. A nonparametric version of Wilk's theorem for the limiting distribution of the empirical likelihood ratio is derived. Compared with methods based on normal approximations, the empirical likelihood does not require consistent estimators for the asymptotic variance and bias. The finite sample behaviour of the proposed method is evaluated with simulation and illustrated with an AIDS clinical trial data set.