“引洮工程”引发的受水区污染治理研究

[目的]为了解决甘肃中部安定区、陇西县、渭源县、临洮县、榆中县和会宁县的人畜饮水、工业用水、生态用水及农业灌溉用水问题,引洮工程通过九甸峡水利枢纽抬高水位将黄河上游洮河支流水资源引入受水区。在受水区,在调水增加本区供水总量的同时,相应增加了增量水资源使用后带来的废污水,客观上对污染治理工作水平提出了更高要求,轻视排污问题将加剧受水区乃至下游的水系污染程度,影响受水区经济社会的可持续发展。[方法]文章采用文献研究法从理论上探讨了环境容量、排污权及其关系。采用定额计量法计算了调水带来的COD和氨氮增量。[结果]调水使得受水区COD和氨氮每年分别增加6 914. 30t和1 440. 48t。就COD而言,受水区平均排放量占该区环境容量的51. 12%,似有较多的容量结余,但区内排放极不平衡,榆中和会宁已经超排。就氨氮而言,受水区平均排放量将占该区环境容量的151. 55%,总体超排很严重。区内除临洮以外,其余5县区均超排,其中,榆中和会宁超排1倍以上。[结论]排污量是假定增量污水符合二级排放标准的前提下计算的,如果处理率低、排放达标率低,则超排现象会更为严重。对此,要从宏观上进行综合治理,诸如完善政府、社会与市场共同治污机制、排污权配置的过渡性制度安排、污水处理企业改革及引导受水区进行产业结构调整等。     

就业结构调整对水库移民土地流转的影响研究*——以南水北调中线工程移民为例

[目的]为促进水库移民的生计恢复及转型,探寻就业结构和土地流转间的交互机制,分析两者间耦合作用对当前移民安置模式及政策的影响。[方法]文章从移民就业结构变迁出发,通过超边际理论构建了安置区移民土地的流转机制模型,推演了从业决策对土地流转行为的影响路径,并运用南水北调农业安置移民数据进行实证检验。[结果]大面积转出土地是移民搬迁后土地处置的主要行为,移民中土地转入户有所增加,但土地集中度却有所减少。移民非农就业较搬迁前有明显上升,并有向当地兼业转移的趋势,但与土地流转间并不互为因果,农村社保还难以弱化其对土地养老的依赖。劳动力数量、非农就业时间、非农收入占比、土地政策等对移民土地流转行为和规模均有显著影响,而外出就业前景和地租水平在促进土地流转行为的同时,却不一定能增加土地流转面积。[结论]移民外迁中可以采用无土安置代替农业安置,推动移民土地流转的关键在于技能培训、政策保障和地租补贴,简单的就业推荐和土地权属划分的作用有限。而对于移民中的农业大户,则需在满足土地转入面积的基础上,保障其在安置区的各项土地权益。     

结构性违约、信用分层与评级机构的策略性反应——来自中国信用债市场的证据

2014年以来，以主要集中于民企的"结构性违约"宣告了中国信用债市场刚性兑付的"结构性打破"，债券市场进入了新的发展阶段。利用2013-2017年债券数据，本文深入分析了结构性违约对评级机构行为和效率的影响，主要有如下发现：首先，信用评级的市场公信力会因政府隐性担保导致的"刚性兑付"而削弱；其次，结构性违约爆发之后，信用评级的整体效率有所提升，但在不同发行主体呈现分化，对于非城投类企业，信用评级对发行利差的影响显著增大，意味着评级公信力的显著提升，而对于城投类企业，评级效率并未明显改善；进一步研究表明，出现这种情况的原因在于评级机构在违约后采取了差异化的评级策略，对于违约风险较大的非城投类债券，评级机构倾向采取"收紧评级"的策略；对于违约风险较低的城投债，评级机构倾向于采取"放宽评级"的策略。这种策略性行为是导致市场"信用分层"的重要原因，并有可能推升民营企业的融资成本。     

复杂山区铁路客运站自动选址研究

无备选站址条件下的客运站自动选址是线站协同优化的前提和基础,而不局限于车站选址的代价最小化,同时考虑连接车站间区间线路的代价具有重要意义。构建复杂山区铁路客运站自动选址模型,首先,建立综合地理信息模型,基于线站一体化的设计理念,实现单个车站选址,确定站心位置及站坪方向;其次,以公路线形优化模型的改进算法完成站—站间自动选线设计;最后,将车站选址代价与区间线路代价紧密结合起来,计算综合代价,实现站址方案的优选。以山区铁路为例对该方法进行验证,结果表明,该方法能高效生成山区铁路车站方案集,并辅助设计人员进行方案优化。     

Sustainable supply chain management and partner engagement to manage climate change information

Climate change poses significant new risks and challenges for businesses and their supply chains. Additionally, in many sectors, Scope 3 indirect greenhouse gas emissions resulting from the sourcing and distribution of goods and services are larger than firms' own carbon footprints. Here we study how firms engage their key stakeholders in their supply chains in obtaining, processing, and transferring relevant climate change‐related information designed to overcome information asymmetry and drive sustainable development. Grounded in organisational information‐processing theory (OIPT), we draw on data from the Carbon Disclosure Project's Climate Change Supply Chain initiative for a qualitative content analysis of a large sample of global firms. Consistent with OIPT, we find that although firms primarily engage their supply chain partners in a variety of ways to reduce information uncertainty around indirect emissions data, effectively interpreting and managing broader sustainability information equivocality becomes a growing priority. Our findings further suggest that firms engage suppliers, customers, and other supply chain partners through basic, transactional, and collaborative types of engagement. We contribute to literatures on interorganisational information processing and sustainable supply chain management by providing a more detailed understanding of how firms engage supply chain partners in the context of climate change.     

中国医疗保险体系中的自选择与医疗费用——基于灵活就业人员参保行为的研究

我国社会医疗保险已实现全覆盖,现阶段的主要问题在于医保基金能否实现可持续运行。在现行制度安排下,灵活就业群体参加城镇职工医疗保险可能存在逆选择问题,随着就业形态日趋多样化,这将加剧基金运行的不平衡。本文基于2012-2014年中国家庭追踪调查数据(CFPS),利用中国特有的制度特征,在实证上将逆选择效应同道德风险相区分,验证了选择参加城镇职工医保的人群是医疗费用较高的人群。估计表明,自愿选择参加城镇职工医保的人群医疗支出明显高于强制参保群体,大约高78%;而选择参加城镇职工医保的人群医疗支出比选择参加城乡居民医保高约45%。灵活就业人员参加城镇职工医保提升了他们的福利,但如何规避潜在的基金运行风险,是医保制度设计中不可忽视的问题。     

CAUSAL INFERENCE ON EDUCATION POLICIES: A SURVEY OF EMPIRICAL STUDIES USING PISA,TIMSS AND PIRLS

The identification of the causal effects of educational policies is the top priority in recent education economics literature. As a result, a shift can be observed in the strategies of empirical studies. They have moved from the use of standard multivariate statistical methods, which identify correlations or associations between variables only, to more complex econometric strategies, which can help to identify causal relationships. However, exogenous variations in databases have to be identified in order to apply causal inference techniques. This is a far from straightforward task. For this reason, this paper provides an extensive and comprehensive overview of the literature using quasi‐experimental techniques applied to three well‐known international large‐scale comparative assessments, such as PISA, PIRLS or TIMSS, over the period 2004–2016. In particular, we review empirical studies employing instrumental variables, regression discontinuity designs, difference in differences and propensity score matching to the above databases. Additionally, we provide a detailed summary of estimation strategies, issues treated and profitability in terms of the quality of publications to encourage further potential evaluations. The paper concludes with some operational recommendations for prospective researchers in the field.     

Relationship between city size and firm productivity – A new interpretation using the Chinese experience

This paper contributes to the literature on the relationship between city size and firm productivity by focusing on agglomeration, selection (market competition), and sorting (presence of firms with diverse productivity) effects using Chinese firm-level data for 1998–2013. Contrary to the existing literature, our parametric regression estimates from nearly two million firms show that when the selection effect is controlled, productivity advantage in big cities is reversed. This outcome is explained through a quantile regression showing the existence of left-sided sorting (inefficient firms sort themselves to larger cities) in big cities which is not captured in existing empirical literature. We further find that (1) left-sided sorting is stronger in exporters than non-exporters; (2) is also generated mainly in enterprises with high asset-liability ratios; and (3) selection has a positive effect on firm productivity, suggesting that market competition is key in an explanation of the rapid growth of big cities in China.     

Customizing calories: How rejecting (vs. selecting) ingredients leads to lower calorie estimation and unhealthier food choices

Customization of food products has increased substantially in recent years while the desire for healthiness and an emphasis on understanding and providing calorie information continues to dynamically change the landscape of restaurant retail. The authors report four studies demonstrating that different customization routes (i.e., rejecting alternatives from a full product offering versus adding alternatives to a basic product offering) lead to systematic, but predictable, differences in consumers’ estimations of calories. In particular, this research finds that a rejection (vs. selection) customization process leads consumers to persistently estimate lower calories in the final product, which then improves evaluations of the retailer and leads to unhealthier food choices. These findings occur when consumers estimate calories of the exact same final product using the different paths to customization as well as when they create their own customized final product, while accounting for differences in the quantity and type of ingredients selected, suggesting a very general difference in estimations. This research has important implications for consumers who want to manage their weight and for firms that need to manage consumers’ health perceptions.     

兰州铁路枢纽总图方案研究

合理确定兰州铁路枢纽布局有助于完善西北地区铁路网络,促进兰州—西宁城市群发展,提升欧亚大陆桥互联互通能力,发挥兰州地区的桥头堡作用。阐述兰州铁路枢纽现状,指出枢纽内客运站分工及货运设施功能存在问题,提出枢纽发展规划;研究提出兰州铁路枢纽总图方案,包括干支线、疏解线及联络线工程方案与总图方案设计。研究结果表明,兰州将形成衔接11条铁路干线,南客北货的大型环状枢纽格局,更好地支撑西北地区核心路网运输。