The impact of climate change on labour demand in the plantation sector: the case of tea production in Sri Lanka

Limited opportunities for crop switching and lengthy preharvesting periods make the plantation sector particularly vulnerable to climate change. Surprisingly, however, the economic consequences of climate change on plantation crops are seldom analysed. Drawing on a unique primary panel data set from a representative cross section of 35 tea estates in Sri Lanka over the period 2002–2014, this study implements a structural model of estate profit maximisation to estimate the elasticity of labour demand with respect to different components of weather. Results indicate a negative relationship between labour demand and rainfall in the south‐west monsoon, the north‐east monsoon and the second inter‐monsoon. A positive relationship is found between labour demand and rainfall in the first inter‐monsoon. Overall, predicted changes in rainfall by 2050 are anticipated to reduce labour demand by approximately 1,175,000 person‐days per year across Sri Lanka's tea plantation sector. This is likely to have considerable social and welfare implications, particularly for the Indian Tamil women who comprise the majority of the sector's workforce.     

Estimating effects of cooperative membership on farmers’ safe production behaviors: Evidence from pig sector in China

This research studies the determinants of pig farmers’ participation in farmers’ cooperatives and the effects of farmers’ cooperatives on pig farmers’ behaviors in adopting safe production practices using data from a household survey of 540 cooperative farmers and 270 non-cooperative farmers from four main pig production provinces in China. The propensity score matching (PSM) method was adopted to deal with possible self-selection bias associated with farmers’ participation in farmers’ cooperatives due to observables, which is further supplemented by a sensitivity analysis to assess the degree to which the PSM results are robust to the presence of unobservables. The PSM results show that the cooperative membership has significant and positive influence on farmers’ propensity to adopt safe production practices and the effects are heterogeneous across a number of key cooperative, farm and household attributes. Specifically, the membership effects tend to be bigger for cooperatives led by Investor-owned firms (IOFs) and farms of small production scale. And the effects tend to be greater for households (1) of medium and high level of education, (2) of less than 10 years of pig production experience, (3) of no off-farm job experience, and (4) that are specialized in pig production. The sensitivity analysis further increases our confidence in the results for the feed use and the breed use, however, the results for vaccination, drug use and waste disposable are more sensitive to the influence of unobservables, therefore should be interpreted with caution.     

一种机载三维音频技术的快速计算方法

针对机载三维音频应用的实时性需求，提出了一种基于单耳相对头相关传递函数和改进型混响模型的机载三维音频快速实现方法，在较传统实现方式性能无明显下降的情况下降低了80%的计算量。对提出的算法在F-16战斗机模拟强噪声环境下进行相关主观试听实验，同时在某型飞机音频系统中实验验证。实验结果表明,所提方法在实时处理3路三维音频时，三维音频方位分辨精度在5°以内，可满足实际机载平台使用需求。     

Accounting for the Gender Technology Gap Amongst Smallholder Rice Farmers in Northern Ghana

Narrowing the gender technology gap in agricultural production has become a critical policy issue in sub‐Saharan Africa. A better understanding of the gender technology gap is essential for policy formulation and programme planning to ensure equity in resource allocation, and household‐level food security in low and middle income countries, such as Ghana. We employ a metafrontier approach to analyse the differences in the efficiency of male and female farmers, recognising the endogeneity of some of the variables in the inefficiency effects model, in particular the credit constraints of the rice farmers under study. Our findings show that while the rice farms themselves are very similar, average yields for male managed farms tend to be significantly higher than female managed farms reflecting higher seeding and fertiliser application rates on male managed farms. However, there is no significant difference between the genders in either land used for rice or total output per farm household. We find some evidence that relative to the metafrontier, male managed farms are less efficient than female managed farms. The results further show gender technology gap amongst the smallholder rice farmers with females’ technology gap ratio being significantly greater than that of males, with females operating on a production frontier closer to the metafrontier. Policies that provide females more access to productive resources and other agricultural services could assist in the generation of relatively higher output.     

基于新知识生产函数的青海高新技术企业创新驱动力研究

基于新经济增长模型,通过岭回归实证检验,分析了青海省高新技术企业创新产出的影响因素。实证结果显示企业内部研发投入和人力资本对创新产出有积极作用,集聚知识溢出水平对创新产出的贡献较大,政府支持力度对创新产出的作用不稳定。最后,结合高新技术企业调研现状和实证结果提出了高新技术企业提高创新产出的对策建议。     

生态文明建设背景财政扶持、林权改革对林业生产效率的影响

基于2000—2016年中国省际面板数据,利用DEA-Malmquist指数法对中国林业生产效率的区域差异和时序变化进行研究,运用面板Tobit模型检验财政扶持对林业生产效率的影响并验证林权改革对二者关系的调节作用。研究发现:在生态文明建设背景下,林业生产效率存在显著的区域差异;技术进步对于全要素生产率的提升起到重要推进作用;财政扶持与林权改革均对林业生产效率产生了正向影响,但林权改革并没有对财政扶持与林业生产效率的关系产生积极调节作用。因此,各省份应当通过加大政府扶持力度、优化投资方式、深化集体林权制度改革等措施促进林业生产效率提升。     

老龄化与碳排放：消费效应还是生产效应？——基于2002-2017年中国省级面板数据的实证研究

人口老龄化是经济增长的一大阻碍,它对碳排放的影响是做出环境政策抉择的关键因素.以中国2002—2017年的省级面板数据为研究样本,从理论与实证两个层面分析人口老龄化与碳排放的关系及影响机制.一方面,构建包含碳排放的世代交叠模型(overlapping generations,OLG),发现老龄化主要通过消费效应和生产效应两个路径对碳排放产生影响;另一方面,从实证层面发现老龄化与碳排放之间存在倒"U"形关系,而且消费效应在人口老龄化与碳排放的关系中起到部分中介作用,生产效应的影响则不显著.     

Fuzzy modelling of static system optimum traffic assignment problem having multi origin-destination pair

Traffic congestion is an unpreventable problem to avoid in a transportation network and it has negative effects on traffic accident, time wasting, traffic delay and safety problem. Besides, in transportation networks, drivers do not want to deal with traffic jam while traversing between specified origin-destination pair. Therefore, traffic assignment (TA) is imperative to improve traffic management, transportation safety, time, and cost savings. System Optimum Traffic Assignment Problem (SOTAP) is a kind of TA model which aims to minimize the total system travel time on the network, and satisfies the flow conservation constraints. To model the SOTAP more realistically, the imprecise parameters can be taken as fuzzy. Therefore, in this paper, we focus on converting the conventional SOTAP to a fuzzy quadratic programming problem (QPP) which is named System Optimum Fuzzy Traffic Assignment Problem (SOFTAP). Here, link travel time is expressed with BPR function as generally used in the literature by converting to fuzzy except link-dependent parameters. Thus, the nonlinear objective function of SOFTAP is expressed in terms of fuzzy link flows and fuzzy link travel times. A solution approach from the literature is modified to the reconstructed SOFTAP.     

环境公平感知、社会信任与农户低碳生产行为*——以农膜、秸秆处理为例

［目的］研究旨在探讨环境公平感知和社会信任与农户低碳生产行为之间的关系，为促进农户生产行为向低碳化方向转变提供对策建议。［方法］基于陕西和甘肃两省的村域调查数据，以农膜和秸秆处理为例，运用二元logistic模型探讨环境公平感知和社会信任对农户低碳生产行为的影响，并结合分层回归分析了社会信任在环境公平感知和农户低碳生产行为间的调节效应。［结果］（1）在环境公平感知维度中，人际公平感知正向影响农户的农膜和秸秆处理行为； （2）对社会信任来讲，人际信任对农户农膜和秸秆处理行为均有显著的促进作用，而制度信任仅对农户秸秆处理行为具有正向影响； （3）人际信任在种际公平感知和农户农膜处理行为之间具有显著的正向调节效应，而制度信任在两者之间具有显著的负向调节效应； 同样，人际信任在人际公平感知和农户秸秆处理行为之间具有正向调节效应，而制度信任弱化了人际公平感知对农户秸秆处理行为的影响。［结论］环境公平感知和社会信任是影响农户低碳生产行为的关键因素，且社会信任在种际公平感知和农户农膜处理行为之间以及在人际公平感知和农户秸秆处理行为之间具有显著的调节作用。     

Bitcoin price and its marginal cost of production: support for a fundamental value

This study back-tests a marginal cost of production model proposed to value the digital currency Bitcoin. Results from both conventional regression and vector autoregression (VAR) models show that the marginal cost of production plays an important role in explaining Bitcoin prices, challenging recent allegations that Bitcoins are essentially worthless. Even with markets pricing Bitcoin in the thousands of dollars each, the valuation model seems robust. The data show that a price bubble that began in the Fall of 2017 resolved itself in early 2018, converging with the marginal cost model. This suggests that while bubbles may appear in the Bitcoin market, prices will tend to this bound and not collapse to zero.