低应变反射波法在PHC管桩完整性检测中的应用分析

根据低应变反射波法检测高强度预应力混凝土管桩(PHC)桩身完整性的原理,通过具体工程实例对低应变反射波检测PHC管桩有关问题进行了分析探讨。     

辽宁省大学生亚健康现状及成因研究

以辽宁省6所不同类型院校的1 200名学生为研究对象,对他们的亚健康现状和影响因素进行了调查,可以看出我省大学生亚健康检出率略高于其他省份。影响辽宁省大学生亚健康症状的主要因素:对自身健康的关注度不够、饮食不规律、缺少合理的睡眠和适当的体育锻炼、闲暇时间睡懒觉及上网聊天打游戏;学校相关部门对学生身体状况的重视程度不够,缺少家人的影响与监督;大学生对未来前程的担忧和就业的压迫感、对自身工作能力的不自信。     

A probabilistic ghost in the experimental machine

This paper focuses on the opposition between two contemporary research programs in economics: behavioral economics (BE) and experimental market economics (EME). Our claim is that the arguments of this opposition can be clarified through the lens of another opposition in the philosophy of probability and in probability theory, between Bayesianism and frequentism. We show how this probabilistic opposition has indirectly shaped a controversy in psychology that opposes two research programs – Heuristics and Biases and Ecological Rationality – which play respective roles in the foundations of individual rationality in BE and EME. To understand these theoretical interrelationships, we investigate the 1996 controversy between Kahneman, Tversky, and Gigerenzer. Those psychologists held different views on how probabilistic representations influence the context-dependency of rationality. This provides a rationale to suggest that a probabilistic ghost may be haunting the experimental machine in economics, and explains how and why the oppositions between BE and EME are structured around the interplay between the norms of rationality and the context in which rationality is exercised.     

关于食品安全问题的几点思考

食品安全从社会层面来看,不仅是公共卫生问题,而是社会问题、政治问题,甚至是社会安定团结问题。因此,食品安全问题科学管治意义重大。针对目前的治理现状,笔者从立法、市场行为价值取向、执法监管及媒介引导四个角度进行了思考,并对这些问题提出了建议性意见。     

Semiparametric estimation of multi-asset portfolio tail risk

When correlations between assets turn positive, multi-asset portfolios can become riskier than single assets. This article presents the estimation of tail risk at very high quantiles using a semiparametric estimator which is particularly suitable for portfolios with a large number of assets. The estimator captures simultaneously the information contained in each individual asset return that composes the portfolio, and the interrelation between assets. Noticeably, the accuracy of the estimates does not deteriorate when the number of assets in the portfolio increases. The implementation is as easy for a large number of assets as it is for a small number. We estimate the probability distribution of large losses for the American stock market considering portfolios with ten, fifty and one hundred assets of stocks with different market capitalization. In either case, the approximation for the portfolio tail risk is very accurate. We compare our results with well known benchmark models.     

New technology and old institutions: An empirical analysis of the skill-biased demand for older workers in Europe

Using panel data from nine European countries over the period 1970 to 2007, we examine the impact of information and communication technology (ICT) on the demand for older workers (aged 50 and over). We find evidence of a decrease in demand for older workers in the 1970s and 1980s. It can be argued that the impact of ICT on demand for older workers is skill-biased. However, the skill-biased demand for older workers is mainly reflected in the skill-biased changes in employment shares rather than relative wages. There is some evidence of a gradual deskilling of older workers. We find that labour market institutions such as the national minimum wage, social pacts on wage issues and union density mostly benefit skilled older workers, while coordination of wage setting, extension of collective agreements, social pacts on pensions and centralisation of wage bargaining can alleviate the adverse effects of skill-biased technological change.     

Investigating the effects of job demands and job resources on cabin crew safety behaviors

Cabin crews are crucial to the cabin safety performance of airlines, and may enhance air travel safety and alleviate passenger concerns. Within the limited literature devoted to cabin crew related research, this study aims to examine the causal relationships among “job demands”, “job resources” and cabin crew safety behaviors. Data from a survey of 339 flight attendants working for Taiwanese international airlines were analyzed using structural equation modeling. A variety of fit indices confirmed the overall model fit, and all the paths in the model were statistically significant. Framed in the context of the job demands-resources model, the results reveal negative causality between “job demands” and “cabin crew safety behaviors”, whereas “job resources” are positively related to “upward safety communication”, “in-role” and “extra-role” safety behaviors. The implications of the results for practitioners and future research are discussed.     

探地雷达在公路改扩建工程检测中的应用

公路改扩建工程在广东省正处于快速发展时期,如何准确得到路面病害情况,是旧路处治方案制定面临的主要问题.依托开阳高速改扩建工程,采用三维探地雷达对旧路进行病害检测,得到道路表面及内部的病害分布情况,并分别与人工徒步调查路况及开挖后内部实际情况进行比对.结果表明:当三维探地雷达检测采样间距设置为2.0 cm、驻波时间设置为0.6 ms、时窗设置为85 ns时,可达到较好的检测精准度;三维探地雷达可实现对路面结构内部不同深度位置的裂缝病害进行探测,精确识别3 mm宽裂缝,并了解裂缝的发展方向及性质.     

Introduction to the special section on subsistence marketplaces

We provide an introduction to the special issue on subsistence marketplaces. We briefly describe the stream of subsistence marketplaces, and the conference series associated with the call for papers. We provide a brief overview of the diverse set of papers in the special section.     

浅谈沟通技巧与执行能力在医院管理工作中的应用

为了不断提升医院管理干部的综合能力,不断推进医院向更高层次的跨越和发展,本文将对沟通技巧与执行能力在医院管理工作中的应用进行深入的探讨。