基于面源污染约束的油菜生产效率时空变化及成因分析

[目的]分析面源污染约束条件下我国油菜生产效率的动态变化、省际差异及其影响因素,提出提升途径。[方法]采用基于非期望产出的非径向、非角度的数据包络分析模型测算面源污染约束下的油菜生产效率,根据投入冗余、期望产出不足或非期望产出冗余等,分析效率损失成因。[结果]我国油菜生产效率总体上呈现"N型"年际变化特征,其中黄淮区、江浙、重庆、青海和甘肃的油菜生产效率均值高于0.9,云贵和内蒙古的油菜生产效率则低于0.8。全国和长江流域省际差异表现为先扩大后缩小趋势,西北区省际差异最大,黄淮区省际差异最小。总氮和总磷排放量过高是长江流域乃至全国油菜生产效率损失的主要原因。近3年总氮可缩减比例均值大于30%的地区从大到小依次为湖南、内蒙古、贵州、云南和江西,总磷可缩减比例均值大于30%的地区依次为云南、贵州、四川和内蒙古。此外,湖北用工投入冗余、内蒙古化肥投入冗余和单产不足也是其油菜生产效率损失的重要原因。[结论]长江流域需重点削减氮磷径流损失,黄淮区应重点控制氮磷淋溶损失,西北区应重点治理氮磷侵蚀流失。     

Measuring Farm and Market Level Economic Impacts of Improved Maize Production Technologies in Ethiopia: Evidence from Panel Data

While it is often recognised that agricultural technology adoption decisions are intertwined and best characterised by multivariate models, typical approaches to examining adoption and impacts of agricultural technology have focused on single technology adoption choice and ignored interdependence among technologies. We examine farm‐ and market‐level impacts of multiple technology adoption choices using comprehensive household survey data collected in 2010/11 and 2012/13 in Ethiopia. Economic surplus analysis combined with panel data switching endogenous regression models are used to compute the supply shift parameter (K‐shift parameter), while at the same time controlling for the endogeneity inherent in agricultural technology adoption among farmers. We find that our improved technology set choices have significant impacts on farm‐level maize yield and maize production costs, where the greatest effect appears to be generated when various technologies are combined. The change in maize yield and production costs results in an average 26.4% cost reduction per kilogram of maize output (the K‐shift parameter). This increases the producer and consumer surpluses by US$ 140 and US$ 105 million per annum, respectively. These changes in economic surplus help to reduce the number of poor people by an estimated 788 thousand per year. We conclude that deliberate extension efforts and other policies that encourage integration of technologies are important for maize technologies to yield their full potential at both farm and market levels.     

税收成本、非税成本与企业组织形式选择——基于经济模型的研究框架

基于税收考虑的企业组织形式选择也称为最优企业组织形式税务筹划,即选择某种企业组织形式寻求最有效的税务筹划决策,税收成本和非税成本是影响这种有效选择的主要因素。不考虑非税成本时,企业组织形式偏好选择经济模型主要受企业所得税税率、股权转让所得的个人所得税税率、经营所得的个人所得税税率等变量影响。非税成本中的转换成本、牺牲非税优势的成本、协调与沟通成本等也是影响经济模型的重要因素。     

ICT diffusion in public administrations and business dynamics: Evidence from Italian municipalities

Public administrations have been adopting information and communication technologies (ICT) to transform their internal organization and provide better public services to citizens and firms. However, the external benefits, despite being deemed relevant, have been empirically overlooked. We first explore the relation between ICT diffusion in public administrations and business demography at the municipal level by studying the Italian context. Our results show that ICT diffusion in the PA contributes to significantly reducing the death rate of firms and boosting their turnover rate. The adoption of ICT in the PA also exerts a positive impact on the firm birth rate, although it is not statistically significant. These results shed light on the importance of promoting e-government and framing coherent digital agendas as public instruments for supporting entrepreneurship and regional economic development.     

创新价值链视角下的区域创新活动收敛分析

基于创新价值链视角,将我国创新活动分为知识创新、科研创新、产品转化创新3个阶段,运用空间面板收敛模型对各类创新活动进行收敛检验,研究结果显示：①空间自回归因子和扰动项的空间滞后因子对创新增长率有显著正向影响,说明创新水平增长在地区间具有显著的空间效应,存在空间示范效应和外生冲击传递效应,同时空间面板模型拟合效果整体上优于普通面板模型,说明我国创新活动收敛中有必要考虑空间因素;②知识创新和知识转化创新水平存在稳定的绝对β收敛,科研创新水平不存在收敛,通过基尼系数时序图验证了我国科研创新活动存在“马太效应”,另外两类创新活动水平则朝着收敛的趋势发展;③高校资源、市场化水平分别对知识创新和产品转化创新收敛有显著促进作用,信息化水平对三大创新活动收敛都有显著的促进作用。     

On Crop Biodiversity, Risk Exposure, and Food Security in the Highlands of Ethiopia

This paper investigates the effects of crop genetic diversity on farm productivity and production risk in the highlands of Ethiopia. Using a moment-based approach, the analysis uses a stochastic production function capturing mean, variance, and skewness effects. Welfare implications of diversity are evaluated using a certainty equivalent, measured as expected income minus a risk premium (reflecting the cost of risk). We find that the effect of diversity on skewness dominates its effect on variance, meaning that diversity reduces the cost of risk. The analysis also shows that the beneficial effects of diversity become of greater value in degraded land.     

食品微生物检验样品采集保存及检验分析

采集和保存样品是食品微生物检验工作的第一步,对后续的微生物检验工作的顺利开展至关重要.食品微生物检验样品的质量和状况对检验结果起着决定性作用.因此,现就食品微生物检验样品的采集、保存、检验过程进行探究,其目的是保障食品微生物检测结果能够真实反映其食品安全现状.     

基于深度学习模型的种植结构复杂区农作物精细分类研究

目的 卫星遥感技术具有覆盖范围广、探测周期短、调查成本低等优势而广泛应用于大区域农作物分类。然而在种植结构复杂区（如城乡结合部）,因其地块破碎、同期生长的作物种类多且分布分散,利用传统的统计分类或机器学习方法进行农作物分类时仍存在精度不高的问题。为提高种植结构复杂区农作物分类精度。方法 文章选取河北省廊坊市广阳区为研究区,以GF-1 PMS全色多光谱融合影像为数据源,采用U-Net、PSPNet及DeepLabv3+,3种深度学习模型进行农作物分类研究。分析模型参数对农作物分类精度的影响,评价3种深度学习模型的农作物分类精度,优选农作物精细分类方法。结果 （1）学习率与3种深度学习模型的分类精度呈正相关关系,较大的学习率（0.01,0.001）下,3种模型收敛速度快,分类精度高。批样本量与模型分类稳定性相关,批样本量设为100时,3种模型的分类稳定性最好。（2）相比PSPNet、DeepLabv3+模型,U-Net模型分类效果最好,总体分类精度为89.32%。（3）GF-1 PMS影像结合U-Net模型可有效提升种植结构复杂区农作物分类精度,大宗作物春玉米、夏玉米的分类精度在80%以上,花生、红薯、蔬菜小宗作物分类精度在60%以上。结论 该研究可为准确获取种植结构复杂区的农作物类型、面积及空间分布信息提供参考依据。     

递延所得税项目、条件稳健性与非条件稳健性

以所得税会计准则的执行以及企业所得税改革为背景,从条件稳健性与非条件稳健性两方面考察了中国上市公司2007～2010年递延所得税项目对会计稳健性的影响,证明了递延所得税资产和递延所得税收益(费用)既导致了非条件稳健性,又导致了条件稳健性；而递延所得税负债引起了条件稳健性,在非条件稳健性方面,不但没有表现出稳健性,反而表现出一定的激进性,说明企业在对递延所得税负债的确认上,不但没有高估负债,反而可能低估负债.     

Renminbi＇s Potential to Become a Global Currency

This paper is a tentative endeavor to delineate the potential of the renminbi to become a global currency. It first analyzes the critical economic, financial and policy attributes that are required to support a currency to gain an international role. It then examines whether China has the potential to acquire these attributes. The paper concludes by offering some provisional observations on the implications for Asia and the global economy, should the renminbi evolve into a world currency in the coming decades.