Agricultural productivity growth in Brazil: Large and small farms excel

The long-standing debate on the relationship between farm size and productivity has been generally limited by the range of farm sizes evaluated and the definition of productivity. In this paper we use data from three Brazilian agricultural censuses to address these issues. In particular, we introduce a wider distribution of farm sizes than presently available from the literature and we employ total factor productivity (TFP) as our performance measure. In doing so, we test which farm size class had the highest TFP levels in 1985 and 2006, how factor productivity growth varied within and across farm size classes between those years, and which policy or factor had the greatest productivity enhancing effect. When examining TFP growth, we move beyond the common decomposition into technical and efficiency changes by identifying the complete distribution of farm productivity performances. We find that by 2006 a U-shaped distribution of productivity over farm sizes had emerged. Considerable 1985–2006 TFP growth differences are prevalent; positive rates for the majority accompany stagnant or negative rates for some. Public education investments were associated with faster productivity growth regardless of farm size, while technical assistance’s positive effect and credit’s negative effect were associated with larger farm sizes. The role of specialization varied by size.     

Measuring industrial upgrading: applying factor analysis in a global value chain framework

ABSTRACT

A key question for promoting international competition is how to improve the position of countries and industries in global value chains (GVCs). The first step is to properly measure industrial upgrading in GVCs. This is not a trivial issue because upgrading has not been defined unambiguously. Several authors have used different (and sometimes related) measures, all of which indicate certain aspects of upgrading. Rather than trying to find the single, ultimate measure of upgrading, we propose a different approach. We examine the multidimensionality of industrial upgrading, using eight indicators in factor analysis. Four of the eight indicators adopt the GVC perspective and include, for example, the growth of the share in value-added exports. We provide three quantitative dimensions of industrial upgrading: process upgrading, product upgrading, and skill upgrading. With these dimensions, we compare and analyze the upgrading of different countries and industries using the World Input–Output Database.     

普惠金融发展的地区差异、收敛性及影响因素研究*——基于中国省级面板数据的检验

本文利用2005—2016年省级面板数据，对我国各地区普惠金融发展水平进行测度，并在此基础上探讨其收敛性及影响因素。结果表明：（1）我国普惠金融发展水平在考察期内总体偏低，并且呈现出显著的地区差异性。（2）绝对β收敛在全国、中部和西部均存在，而东部不存在；条件β收敛在全国、东部和西部均存在，而中部不存在。（3）政府干预程度、市场化程度、人力资本质量、非正规金融以及外商直接投资对普惠金融发展均具有重要的影响。     

Viewpoint: Soda taxes – Four questions economists need to address

The popularity of soda taxes as a public health policy has grown rapidly in the last few years. While the evidence that the tax works in reducing the purchases of soda is emerging, there are a number of questions that are yet to be answered before the broader effectiveness of this measure can be determined. Beyond health effects, there is more specifically a need to better understand the economic mechanisms of change, redistributive effects, as well as causal and spillover effects in food systems and economy more broadly.     

The equity impacts of bus rapid transit: A review of the evidence and implications for sustainable transport

The paper offers an analysis of empirical evidence on the equity impacts of operational Bus Rapid Transit (BRT) systems in the Global South. The focus is on vertical equity, i.e. whether BRT systems achieve progressive benefits for poorer segments of the population. Findings from Africa, Asia, and Latin America all suggest that BRT does offer significant benefits to low-income groups, in terms of travel time and cost savings, access enhancement, and safety and health benefits. However benefits are often skewed toward medium-income users and thus less progressive than they might be. Two primary reasons for this are insufficient spatial coverage and inappropriate fare policies. While many features of BRT potentially allow it to deliver pro-poor outcomes, such outcomes only materialize if BRT implementers pay specific and sustained attention to equity. The paper identifies key issues that need to be addressed to steer BRT implementation toward more socially sustainable outcomes—including better integration with other transit, paratransit, and nonmotorized transport services, and with the housing sector.     

纤维蛋白胶粘合法联合神经生长因子治疗周围神经损伤的临床疗效

目的探讨纤维蛋白胶(FG)粘合法联合神经生长因子(NGF)治疗周围神经损伤的临床疗效。方法选取我院2006年8月至2013年10月就诊的124例腓总神经损伤患者,随机均分为两组,对照组患者单纯使用缝合法,试验组患者在缝合法的基础上配合使用FG粘合法联合NGF治疗,随访6个月以上,分析两组患者的运动功能和患肢感觉疗效。结果试验组患者总有效率明显优于对照组,差异有统计学异议(P<0.05)。结论周围神经损伤的修复与再生过程中使用FG粘合法联合NGF治疗,可有效改善患者症状,安全性高,不良反应较少。     

Defining Ownership: An empirical assessment of the ownership measures

Ownership is considered to be one of the crucial governance mechanisms; however, there have been no systematic attempts at validating the construct and measures used to operationalize ownership. We review the current understanding of ownership and the measures used by each perspective, namely blockholder/dispersed shareholder perspective, owner identity perspective, and aggregated ownership perspective. We thereafter critique each of these perspectives, offer hypotheses regarding their validity, and empirically assess each ownership measure vis‐à‐vis firm performance outcomes. We utilize a sample of 3,990 US firms to test our hypotheses and find no consistent results for the blockholder measure, or for the owner identity measure. However, the aggregated ownership measure consistently accounts for significant increases in explanation of variance in firm performance. Copyright © 2018 ASAC. Published by John Wiley & Sons, Ltd.     

山西省乡村休闲旅游地空间分布特征及影响因素研究

［目的］通过对山西省乡村休闲旅游地的空间分布特征及影响因素进行研究，旨在为山西省的乡村旅游发展提供合理的参考建议。［方法］选取山西省213处国家级和省级乡村旅游示范点为研究对象，运用最临近点指数对其空间分布类型进行判别，并运用地理集中指数和地理联系率对其分布均衡程度和地理联系程度进行考量，通过核密度图进一步分析其空间分布指向，在此基础上对影响因素进行分析。［结果］山西省乡村休闲旅游地空间分布呈集聚分布的特点，且与经济规模和人口密度在空间上的均衡、配合程度较高。［结论］（1）山西省乡村休闲旅游地包括以太原和晋中为主的中部密集区和以临汾、运城、晋城为主的南部密集区，且都以各地级市为中心向周边扩展，大多数示范点分布于城郊地区； （2）经济发展、人口密度、资源禀赋、区位因素和社会因素是影响山西省乡村休闲旅游地分布的主要因素，其中农业科技类、农事体验类和特色村镇类多分布于经济和人口密度较高的地区。     

基于限制因素组合序列的耕地质量提升潜力研究*——以什邡市为例

[目的]通过分析什邡市耕地质量现状,充分把握影响耕地质量的主导因素并进行质量提升分区,测算不同质量提升区的提升潜力,以期为全市耕地质量的建设与发展指明方向。[方法]依据农用地分等理论,构建2014年什邡市耕地质量限制性指数评价体系,采用限制性指数模型测算耕地质量限制性指数,结合因素组合法、耕地质量潜力测算法,分别进行耕地质量提升分区及其提升潜力评价。[结果]什邡市耕地质量现状差异显著,地域分布特征明显;因素限制程度以中限制为主,多因素共同主导限制耕地比重大;各质量分区限制特征明显,各区耕地质量提升潜力在时序上和空间上也存在差异。高等别耕地集中分布于南部平原,受土壤酸碱度中等限制和剖面构型高程度限制为主;北部丘陵区以及南部河谷低洼地带主要为低等别耕地,表现为坡度与灌溉因素较高程度限制为主;综合提升潜力较大的耕地集中于北部丘陵区与南部河谷低洼地带。[结论]什邡市范围内耕地质量差异明显,存在普遍限制且分区限制特征明显,各区提升潜力空间差异明显。     

Functional Itô calculus†

We extend some results of the Itô calculus to functionals of the current path of a process to reflect the fact that often the impact of randomness is cumulative and depends on the history of the process, not merely on its current value. We express the differential of the functional in terms of adequately defined partial derivatives to obtain an Itô formula. We develop an extension of the Feynman-Kac formula to the functional case and an explicit expression of the integrand in the Martingale Representation Theorem. We establish that under certain conditions, even path dependent options prices satisfy a partial differential equation in a local sense. We exploit this fact to find an expression of the price difference between two models and compute variational derivatives with respect to the volatility surface.