快速城镇化地区不同生计类型农户耕地利用集约度评价 ——以上海市青浦区为例

研究目的:针对快速城镇化地区农户生计分化现象,以上海市青浦区为例,对不同生计策略类型农户的耕地利用集约度进行评价,并分析其影响因素,以期为改善农户土地利用行为、实现土地资源合理高效利用与农户生计可持续发展提供政策参考。研究方法:运用价值形态测度方法核算各生计类型农户的耕地利用集约度,以两水平方差成分模型确定耕地利用集约度影响因素。研究结果:(1)不同生计策略类型农户耕地利用集约度存在差异性,大小顺序依次为专业农业型、传统农业型、农业兼业型、非农兼业型,劳动集约度与资本集约度排序与之基本一致;(2)同一生计策略类型农户的耕地利用集约度存在相似性,耕地利用集约度的总变异中有24.32%是由农户生计策略类型不同而引起的,水平一中农业收入比重、农业补贴、耕地面积、地块平均离家距离、农户离集镇距离与水平二中是否兼业等是影响农户耕地利用集约度的显著因素;(3)模型拟合效果评价表明该方法具有可行性。研究结论:耕地利用集约度不仅与农户自身禀赋有关,而且受生计类型影响,政府相关部门应结合当地实际情况引导农户对这两方面进行调整或完善。     

桑叶配方颗粒物质基准研究

桑叶配方颗粒迄今尚没有统一的质量标准。为提升桑叶配方颗粒的内在质量,对其物质基准评价方法进行了研究。选取具有代表性产地的15批桑叶制备物质基准,采用高效液相色谱法,以芦丁、异槲皮苷、紫云英苷作为评价指标,确定桑叶物质基准的出膏率范围、标志性成分含量及转移率范围,采用超高效液相色谱法,建立物质基准UPLC特征图谱,并对其主要成分进行指认。结果表明:15批物质基准中,芦丁转移率为19.94%～34.05%,异槲皮苷转移率为11.67%～43.58%,紫云英苷转移率为10.73%～43.05%;物质基准特征图谱中,标定了14个共有峰,指认出7个色谱峰,分别为新绿原酸、绿原酸、咖啡酸、芦丁、异槲皮苷、槲皮素-3-O-(6″-O-丙二酰基)-β-D-葡萄糖苷、紫云英苷。所建立的基准评价方法为桑叶配方颗粒质量标准的制定及其后续大规模生产提供了数据基础。     

Diversification and sophistication of livestock products: The case of African countries

This study assesses the level of sophistication of livestock products in Africa by evaluating technology intensity and economic complexity of each product. Using trade data from 1995 to 2012, livestock commodity exports are classified based on technology intensity. Employing a method of reflection in computing the economic complexity of export products, we find that one fifth of African livestock commodity exports are manufactured with low technology while the rest is composed of raw materials. The results also show that the ten most complex livestock commodities represent about a third of African livestock total exports while the world level is almost double this figure. Yet African countries spend a huge share of their wealth on importing complex products. The results imply that by exporting non-complex products Africa loses nearly a third of the total value of its livestock exports. To boost the value of livestock products, African countries should exploit their untapped potential while securing the domestic market to achieve import substitution. This can be done by integrating with global value chains or developing niche markets at the regional or international markets and improving productive capabilities.     

Cox Point Processes: Why One Realisation Is Not Enough

We review a rich class of point process models, Cox point processes, and illustrate the necessity of more than one observation (point patterns) in performing parameter estimation. Furthermore, we introduce a new Cox point process model by treating the intensity function of the underlying Poisson point process as a random mixture of normal components. The behaviour and performance of the new model are compared with those of popular Cox point process models. The new model is exemplified with an application that involves a single point pattern corresponding to earthquake events in California, USA.     

关键驱动力作用下的新疆生态系统服务时空格局分析

[目的]恶劣的生态环境和有限的资源驱动着新疆特殊生态系统服务的形成,人类又通过对生态系统服务的消费来满足和提高自身福祉,需要研究其时空变化并辨识主要驱动因素,支持区域可持续发展。[方法]文章构建了融合不同土地利用类型生态系统服务的价值量排序及服务功能强度矩阵的生态系统服务评估体系,并耦合3种关键驱动因子以评估各个因子的驱动强度,实现对生态系统服务热点与冷点变化的驱动及迁移分析。[结果]2000—2010年全疆生态系统服务总体增加,这一时期生态系统服务的热点区大部分转变为2010—2015年的冷点区,且15年来生态系统服务总体呈现小幅下降趋势。3个时期北疆和南疆人为干扰强度均呈增加趋势,由其驱动的生态系统服务则相应减小;南疆地区植被覆盖范围极其有限,故对生态系统服务驱动强度低;降水在北疆和南疆都能够产生高生态系统服务,但降水量的不稳定性能够使生态系统服务产生较大波动。相比于南疆地区,北疆生态系统在外界干扰下能够体现出更强的抗性和整体性,从而实现相对高效的生态系统服务输出。[结论]对关键驱动因子作用下的生态系统服务进行时空变化分析,有助于理解当地生态系统产生变化的原因,从而为当地生态环境保护提供参考。     

Changing land use intensity in Europe – Recent processes in selected case studies

In recent decades the intensification of agricultural production in many European countries has been one of the key components of land-use change. The impact of agricultural intensification varies according to national and local contexts and a greater understanding of the drivers of intensification will help to mitigate against its negative impacts and harness potential benefits. This paper analyses changes in land use intensity in six case studies in Europe. A total of 437 landowners were interviewed and their responses were analysed in relation to changes in land use intensity and agricultural production between 2001 and 2011. In the case studies in Western and Eastern Europe we observed stabilisation during the last decade, and no clear tendency of increase or decrease of land use intensity. The use of fertilizers and pesticides seems to have decreased in our cases in Western Europe, which is contrary to trends in Eastern Europe. Agricultural production remained stable in almost all cases, except for an increase in Austria and Romania which may indicate that the farming efficiency has increased. A statistical analysis showed a division between study areas in Romania and Austria (increasing land use intensity) versus those in the Netherlands, Denmark and Greece (decreasing). In the Mediterranean cases we observe a process where agriculture is becoming increasingly marginalised, at the same time as changes in function with regard to urbanisation and recreational land uses have taken place. Logistic regression highlighted the importance of farm size and farmer type in understanding changes in land use intensity. The dominant pattern of stabilisation which has occurred over the past 10 years may also partly be a result of effective EU and national environmental and agricultural policies, which are increasingly concerned with improving environmental conditions in rural areas.     

对国内外砂土地震液化评价介绍及比较

本文通过应用国内外不同的勘察规范对同一个工程场地的地震液化等级划分的计算及评价介绍,得出了一个采用不同规范,可取得比较一致的地震砂土液化等级的结论。     

ARBITRAGE‐FREE BILATERAL COUNTERPARTY RISK VALUATION UNDER COLLATERALIZATION AND APPLICATION TO CREDIT DEFAULT SWAPS

We develop an arbitrage‐free valuation framework for bilateral counterparty risk, where collateral is included with possible rehypothecation. We show that the adjustment is given by the sum of two option payoff terms, where each term depends on the netted exposure, i.e., the difference between the on‐default exposure and the predefault collateral account. We then specialize our analysis to credit default swaps (CDS) as underlying portfolios, and construct a numerical scheme to evaluate the adjustment under a doubly stochastic default framework. In particular, we show that for CDS contracts a perfect collateralization cannot be achieved, even under continuous collateralization, if the reference entity’s and counterparty’s default times are dependent. The impact of rehypothecation, collateral margining frequency, and default correlation‐induced contagion is illustrated with numerical examples.     

The role of inventories and capacity utilization as shock absorbers

We examine the role of inventories and capacity utilization (of both capital and labor) for the propagation of business cycle fluctuations. We document a new set of facts regarding the U.S. cyclical regularities of inventories and capacity utilization. First, we find that capital utilization and the flows of services from both capital and labor are procyclical, and comove with the holdings of inventories. Second, we find that labor utilization is procyclical as well, but is weakly negatively correlated with inventories. We build a model that accounts for these facts, and also accounts for the stylized inventory facts, i.e., inventory holdings are procyclical, while the inventory-to-sales ratio is countercyclical. The analysis is centered on the effects of two possible shocks: preference (demand) shocks and technology shocks. Our model shows that inventories and the rate of capital utilization are mostly complements, while inventories and the rate of labor utilization are mostly substitutes. It further shows that temporary demand shocks emphasize the role of inventories as being a “shock absorber,” whereas high-persistence demand shocks, as well as technology shocks of any persistence, emphasize the role of inventories as being a complement to consumption.     

Revisiting carbon disclosure and performance: Legitimacy and management views

With corporate disclosure of carbon emissions rapidly increasing, the long-standing question remains whether carbon disclosure has any influence on the improvement of carbon performance. Previous studies of environmental disclosure and performance have predominantly focused on whether disclosure is a substitute for poor performance. Little attention has been devoted to the more important question about how changes in disclosure may lead to subsequent changes in performance over time. Following the rationales taken by the legitimacy and management perspectives, we revisit the relationship between carbon disclosure and performance, with a focus on changes that disclosure may (or may not) create. Using a change analysis of Global 500 companies and their carbon emission and disclosure data released between 2008 and 2012, this study finds that the change in carbon disclosure levels is positively associated with a subsequent change in carbon performance (examined through direct and indirect carbon emission intensities). Thus, regardless of whether disclosure has been used as a legitimising tool for prior poor performance, this study confirms that carbon disclosure motivates companies and creates an ‘outside-in’ driven effect for subsequent change and improvement in carbon performance. However, the association between changes in carbon disclosure and performance is relatively weaker in high energy-intensive firms.