Testing homogeneity in semiparametric mixture case–control models

Parametric and semiparametric mixture models have been widely used in applications from many areas, and it is often of interest to test the homogeneity in these models. However, hypothesis testing is non standard due to the fact that several regularity conditions do not hold under the null hypothesis. We consider a semiparametric mixture case–control model, in the sense that the density ratio of two distributions is assumed to be of an exponential form, while the baseline density is unspecified. This model was first considered by Qin and Liang (2011 Qin, J., Liang, K.Y. (2011). Hypothesis testing in a mixture case–control model. Biometrics 67(1):182–198.[Crossref], [PubMed], [Web of Science ®] , [Google Scholar], biometrics), and they proposed a modified score statistic for testing homogeneity. In this article, we consider alternative testing procedures based on supremum statistics, which could improve power against certain types of alternatives. We demonstrate the connection and comparison among the proposed and existing approaches. In addition, we provide a unified theoretical justification of the supremum test and other existing test statistics from an empirical likelihood perspective. The finite-sample performance of the supremum test statistics was evaluated in simulation studies.     

去工业化促进了服务业效率提升吗

世界产业发展史表明,当一国进人工业化中后期,随着生产效率大幅提升,其产业结构演变亦呈现出明显的去工业化特征.以工业化国家为参照,现阶段我国人均收入远未达到工业化国家去工业化时的水平,此时收缩工业产出和就业规模,可视为一种被动去工业化,客观上不利于服务业效率的提升.本文利用2005-2014年我国制造业和服务业数据估计了去工业化对服务业效率的影响.在控制住市场结构和所有制结构等因素的影响后,研究结果显示:①去工业化与服务业效率之间呈现负相关关系;②去工业化通过提高劳动力成本对传统服务业效率产生负效应;③去工业化通过削弱制造业对服务业的有效需求从而不利于生产性服务业效率的提升.     

异质性产品质量与出口加成率

相对于已有研究分析生产率、目的市场选择和市场竞争等因素对出口加成率影响的视角,本文采用2000-2007年企业层面数据测算了28个细分制造业出口产品质量指数及按照会计方法处理的出口加成率,对中国制造业行业产品质量与出口价格加成率的关系进行实证分析.研究结果表明:出口加成率总体并没有随产品质量而提升,但影响因产品质量的异质性而存在差异,劳动密集型制造业出口产品质量显著提高了加成率,而技术和资本密集型产业仍处于阶段性“加成率陷阱”.     

环境公共治理政策的效果评价与优化组合研究

本文构建了包含环境治理体系的动态一般均衡模型,基于模型的研究发现,在经济增长方面生产者补贴较为有效;而技术研发补贴在技术进步中的作用十分显著,其通过“研发投入→绿色技术提升→降低污染物排放”的路径可以实现环境质量的改善.此外,本文还模拟了生产者补贴和技术研发补贴的政策组合对社会福利和污染排放的影响,结果显示,政府可以采用生产者价格补贴或技术研发补贴促进产出水平增长进而提高社会福利水平,同时增大生产者价格补贴和技术研发补贴的幅度则能够通过提高技术水平促使污染水平不断下降.最后,本文给出了社会福利增进与环境质量改善双重目标下生产补贴和技术研发补贴政策的可行性区域,进行了环境公共治理政策的优化组合研究.     

基于化学反应算法的鲜活农产品配送路径优化

文章通过引入时间价格因子考虑在鲜活农产品配送过程的损耗并结合运输成本和惩罚成本构建数学模型.从实际的运用环境出发,考虑到未在期望获得时间内达到运输地点的成本消耗,并且随着时间的推移,鲜活农产品本身也有成本损耗构建目标函数.根据该模型的特点设计化学反应的最小单元分子结构和算法步骤.运用化学反应算法可以很好地解决模型算法过早收敛于局部最优问题.通过实例验证了模型和算法的有效性和科学性.     

基于累积和控制图改进的累积得分控制图

文章针对双边的区域控制图的累积得分思想,设计单边累积得分控制图.利用马尔科夫链的方法计算其平均链长,并与传统的控制图比较.结合快速初始响应方法,设置改进控制图的初始响应值,与带有初始响应的累积和控制图进行过程失控的平均链长的对比.在存在偶然性因素下,改进控制图与传统累积和控制图比较.     

中国—东盟自贸区“升级版”背景下中泰水果贸易发展的优化建议

基于中泰两国地缘差异性及资源禀赋互补优势,双边水果贸易合作发展取得了令人瞩目的成效,贸易总量持续增长,贸易地位日益凸显,成为两国经贸合作的重要内容.中泰水果贸易合作中仍存在着:水果种类单一、深精加工有限、附加值较低、互补优势尚未充分挖掘、贸易便利化水平不高、国际与地区竞争激烈等突出问题.在打造中国—东盟自贸区“升级版”新形势下,中泰两国应充分立足互补性优势,构建水果商品贸易信息合作平台,增强宣传与培育特色品牌,完善运输渠道与减低物流费用,挖掘国内潜在市场,促进双边水果贸易合作取得更大的成效.     

The impact of age,BMI and sex hormone on aging males’ symptoms and the international index of erectile function scores

Objective: To analyze the impact of age, BMI and sex hormone on aging males’ symptoms (AMS) and the 5-item version of the international index of erectile function (IIEF-5) scores in middle-aged and elderly Chinese men.

Methods: A population-based cross-sectional study was conducted in Jiashan County. A total of 969 men, aged between 40 and 80 years old, were admitted. Physical examination and the sex hormones were measured, and AMS and IIEF-5 scores were assessed.

Results: The oneway ANOVA analysis indicated older age groups had higher AMS total-scores, somatic and sexual sub-scores, and lower IIEF5 scores (all p?r_pairwise) analyses showed the significant associations between AMS and age or sex hormone (cFT, Bio-T, SHBG, and LH) levels, and similar for IIEF5. However, when age was adjusted, the correlation coefficients (r_partial) weakened, and correlation significance disappeared, except LH (for AMS: r_partial?=?0.096, p?=?.009; for IIEF-5: r_partial?= ?0.140, p?=?.001). Multiple linear regressions confirmed the influence of increased age and LH on the AMS and IIEF5 scores.

Conclusion: CFT, Bio-T and SHBG failed to yield any additional predicting information when age was adjusted. To improve the male reproductive health, future research should pay more attention on aging-related comorbidities and how to improve general wellness.     

A transnational networked public sphere of air pollution: analysis of a Twitter network of PM2.5 from the risk society perspective

ABSTRACT

Drawing on digitaltrace data, publicly accessible government documents, and journalistic reports, this research integrates Beck’s risk society theory with digital media theories to examine the mediated process of risk definition and assessment of PM2.5 (particulate matters with a diameter less than 2.5 micrometers) in a networked public sphere. Network and content analysis of a PM2.5 Twitter network shows that political and professional elite remained the most powerful producers of risk definition. Established media played a key role, yet faced challenges from a variety of actors who disseminated and filtered information. Laypersons, while peripheral, actively interacted with elite and established media. The blurring geographic boundary in the PM2.5 Twitter network revealed an emerging transnational public sphere, which, however, was segregated by language. This research advances a layered understanding of the contingent, paradoxical media impact for social changes in a risk society.     

基于多源遥感的城市生态用地识别及生态风险评价

随着城市化进程的不断推进、建设用地不断扩张,城市生态空间正处于剧烈变化中。大量具有生态价值和服务功能的土地不断被侵占,以满足暂时的城市建设需求。但从长远来看,这些生态用地的"消失",将不可避免的影响区域生态平衡,给区域经济的健康发展埋下隐患。广州作为华南的中心城市,改革开放以来,大量外来人口涌入,土地利用变化频繁,生态环境的保护面临着巨大压力。因此,本文基于多源遥感数据,利用监督分类法与综合指数法相综合的复合提取方案对2016年广州生态用地进行空间识别,掌握广州市生态用地存量现状。同时,借助生态风险小区和生态风险等景观指数对广州进行了生态风险评估,结果显示,广州市生态风险呈现明显的多核圈层结构,由多核心的中心向外部逐渐降低。