毛乌素沙漠与黄土高原过渡带气候变化对玉米产量的影响

基于1971~2012年榆林市气象数据和玉米产量数据,分析过去42年毛乌素沙漠与黄土高原过渡带玉米生长期内气候因子的变化趋势,并利用一阶差分法、相关分析、多元逐步回归法分析各生育阶段气候因子对玉米产量的影响。研究结果表明:过去42年,玉米生长期内热量资源呈显著增加的趋势,生长期平均温度、平均最高温度和平均最低温度分别增加0.24℃/10 a、0.26℃/10 a和0.32℃/10 a,降水量、光照时数无显著变化。一阶差分、回归分析结果表明,玉米产量与全生长期平均温度、平均最高温度、积温呈极显著的负相关,其中与平均温度相关系数最大,全生长期温度每升高1℃,玉米减产835.5kg/hm2;与降水量变化呈显著正相关,降水量每增加100mm,玉米增产364.7kg/hm2;与日照时数变化呈负相关,日照时数每增加100h,玉米减产325.8kg/hm2。各生育阶段中,出苗-三叶期至灌浆乳熟期的平均最高温度、平均温度及苗期日照对玉米产量产生负影响,七叶-拔节期的降水和成熟期的平均最高温度对玉米产量产生正影响;多元逐步回归模型分析结果表明,显著影响玉米产量的是抽雄-开花期和灌浆-乳熟期平均最高温度、拔节期降水量、出苗-三叶期日照,模型能够解释毛乌素沙漠与黄土高原过渡带玉米56%的产量变化。     

Spatial assessment of climate change vulnerability at city scale: A study in Bangalore,India

Integrating adaptation and mitigation response actions to climate change in urban-level policies requires comprehensive information on vulnerability patterns, yet a majority of local governments and decision makers in various cities in developing nations lack spatially explicit information on climate change vulnerability and its key drivers. In addition, there is no standardised method for an all-inclusive vulnerability assessment at the local level. Results from higher broad-scale vulnerability assessments are difficult to implement conceptually and technically at the local scale. We present a climate change vulnerability assessment approach at the city scale that considers three main components: exposure, sensitivity and adaptive capacity. Indicators were assessed within each component and were combined using Spatial Multi-Criteria Evaluation (SMCE). The standardisation of indicators under each component was conducted, along with weighting, at each level of the vulnerability assessment hierarchy. The vulnerability assessment approach was applied to an urban area in India; namely, Bangalore metropolitan area. The application of vulnerability assessment approach was demonstrated and a spatial assessment of climate change vulnerability patterns was presented. The spatial pattern of vulnerability identifies areas urgently requiring attention to adaptation action, while vulnerability assessment enables policy intervention and prioritization at local spatial scales. This study presents a rational to integrate vulnerability assessment approach within the urban planning realm in Bangalore metropolitan area where according to our study approximately 91% of the area is facing high degree of climate vulnerability.     

服务外包与我国南方地区农业机械化发展——理论逻辑与经验分析

文章通过梳理已有文献针对土地规模对农户机械技术采纳行为影响的相关观点,理顺其中问题与逻辑,指出我国南方地区在人多地少的特殊农情与农地流转高交易成本的约束下,单纯追求经营个体增加土地面积的发展惯性并不能有效解决机械技术应用的规模性要求,过度依赖农地流转集中扩大经营规模从而推进农业机械化的道路存在一定理论与政策上的误导,需转向以"服务流动"聚合众多小农户机械服务需求的农机服务外包的机械化发展路径。进而,利用广东农户问卷数据,采用Logistic模型,实证考察影响农户农机服务外包行为的因素。研究发现:土地经营规模与土地流转面积对农户农机服务外包影响不显著,但土地细碎化是农户选择农机服务外包的重要制约因素;务农劳动力"老龄化"与"女性化"对农户农机外包的影响并不显著,但农业雇工市场工价、农户的受教育水平、组织化程度及非农收入等禀赋因素及区域政策环境与经济环境变量的区域因素有显著的正向作用。     

针对供应信息共享的供应链模型设计与仿真分析

对供应信息共享情况下供应链整体效益的优化程度进行定性与定量分析，分别对供应商、制造商、零售商绩效建立数学模型，并运用Matlab仿真证明了供应信息共享有利于供应链节点企业成本和利润的优化，提出信息共享是成本优化的关键第一步。     

上海大众汽车预批量生产CKD零件准备

上海大众新车型正式投产前需要经历预批量生产阶段，由物流部门负责零件的准备工作。文中介绍了上海大众预批量生产的过程，预批量生产阶段CKD（Completely Knocked Down）零件的准备方式、订购流程和系统架构，并对预批量订货管理提出了优化。     

Investing in guanxi: An analysis of interpersonal relation-specific investment (RSI) in China

This study contributes to a more comprehensive understanding of relation-specific investment (RSI) in interfirm exchanges by introducing a construct for interpersonal RSI. Drawing on economic sociology and qualitative findings, we examine interorganizational RSI and interpersonal RSI as distinct constructs and uncover their roles in relationship performance. In particular, our study focuses on the Chinese interfirm context, in which interpersonal RSI, based on the indigenous practice of guanxi (cultivating social connections), is known as guanxi investment. We adopt a qualitative approach to explore the elements of guanxi investment, and then develop a behavioral measurement scale as a tool for further research. We employ an empirical survey to test and affirm the validity of the scale. The results confirm that in addition to their respective effects, interorganizational and interpersonal RSIs exert an interactive effect on interfirm relationship performance. We offer managerial implications for firms that operate in China.     

我国不同规模企业跨境电子商务应用状况调查分析

根据问卷调研，分析了我国不同规模企业在跨境交易中电子商务的应用水平以及存在的问题。研究发现，跨境电子商务的应用水平由小型企业、中型企业到大型企业逐步升高；对于不同规模企业而言，跨境电商的发展不同，且同一规模企业在跨境交易的不同环节运用电子商务的能力也存在差异。为此，分别从企业、政府、国家层面提出提高跨境电子商务应用水平的意见。     

Why Do Stock Prices Drop by Less Than the Amount of the Dividend? Evidence from a Unique Environment

Abstract:

This paper investigates the effect of a lack of an automated limit order adjustment mechanism on ex-dividend day stock price behavior in a unique environment in which there are no taxes on dividends and capital gains. It finds that the overnight drop in the ask price is smaller than the overnight drop in the bid price. In addition, the study finds that average price drops are smaller than the dividend amount for all dividend sizes. I also find no evidence of a sawtooth-shaped relationship between the dividend amount and the ex-day price drop. These results are generally consistent with the lack of an automated limit order adjustment mechanism.     

Confronting the threat of nuclear winter

Large-scale nuclear war sends large quantities of smoke into the stratosphere, causing severe global environmental effects including surface temperature declines and increased ultraviolet radiation. The temperature decline and the full set of environmental effects are known as nuclear winter. This paper surveys the range of actions that can confront the threat of nuclear winter, both now and in the future. Nuclear winter can be confronted by reducing the probability of nuclear war, reducing the environmental severity of nuclear winter, increasing humanity's resilience to nuclear winter, and through indirect interventions that enhance these other interventions. While some people may be able to help more than others, many people—perhaps everyone across the world—can make a difference. Likewise, the different opportunities available to different people suggests personalized evaluations of nuclear winter, and of catastrophic threats more generally, instead of a one-size-fits-all approach.     

非对称信息下政府对企业节能减排激励机制研究

综合考虑经济增长与节能减排的双重任务,将消费者购买行为、节能减排努力准入标准、政府监督信号考虑在内,构建了政府与企业之间的多任务委托‐代理模型。分别探讨了对称信息和非对称信息下政府如何设计有效的激励机制,鼓励和引导企业积极进行节能减排。结果表明:节能减排努力市场准入标准越高,政府应给与企业越多的固定补贴;政府应根据观测到的企业不同节能减排努力水平设计激励机制;政府监督对促进企业节能减排具有重要作用。