中国畜牧业高质量发展水平的空间差异与动态演进

目的 推动畜牧业高质量发展是稳秩序、保民生的现实需要,科学设计评价体系和开展测度分析是实现畜牧业高质量发展的内在要求。方法 文章依据畜牧业高质量发展内涵特征,构建涵盖绿色循环发展、供给提质增效、经营管理优化3个维度的中国畜牧业高质量发展水平评价体系,对2010—2019年全国及31省（市、自治区,不含港澳台）畜牧业高质量发展水平进行测度分析。结果 （1）2010—2019年全国畜牧业高质量发展水平提升19.20%,时间上具有向好发展态势,空间上呈现自西向东发展水平依次提高的格局;（2）全国发展水平具有空间非均衡性特征,总体发展差距持续扩大、东部地区内差距扩大态势明显、东部与西部两地区间差距最大,地区内差距是畜牧业高质量发展水平地区差距的主要来源;（3）全国畜牧业高质量发展单极化趋向逐步凸显,从长期看三大区域均存在发展差距扩大的倾向,但呈现中东部趋向多极化、西部趋向单极化的变化态势。结论 发展畜牧业应当坚持生产规模与资源环境相匹配,因地制宜构建适应高质量发展方向的生态生产型体系,积极发挥好东、中、西部地区在技术、资金、资源等生产要素方面的优势,探索种养结合、草牧一体的现代畜牧业。     

高等教育发展与中国制造业结构升级

探究高等教育发展对制造业结构升级的影响和作用机制,有助于推进中国制造业结构升级的进程。基于2008—2017年中国27个省（市、自治区）的省际面板数据,借助中介效应模型,探究了高等教育发展对制造业结构升级的影响及作用机制。研究表明,高等教育可以通过提高人力资本积累、促进技术创新这两条路径推动中国制造业结构升级。行业异质性检验表明,高等教育发展对劳动密集型制造业影响显著为负,对技术密集型制造业影响显著为正;区域异质性分析表明,中部地区高等教育发展对制造业结构升级有显著正向影响。完善高等教育投资体系,并在区域间合理配置高等教育资源以及优化人才培养的学科专业设置,对中国制造业转型升级至关重要。     

Statistical Decision Problems and Bayesian Nonparametric Methods

This paper considers parametric statistical decision problems conducted within a Bayesian nonparametric context. Our work was motivated by the realisation that typical parametric model selection procedures are essentially incoherent. We argue that one solution to this problem is to use a flexible enough model in the first place, a model that will not be checked no matter what data arrive. Ideally, one would use a nonparametric model to describe all the uncertainty about the density function generating the data. However, parametric models are the preferred choice for many statisticians, despite the incoherence involved in model checking, incoherence that is quite often ignored for pragmatic reasons. In this paper we show how coherent parametric inference can be carried out via decision theory and Bayesian nonparametrics. None of the ingredients discussed here are new, but our main point only becomes evident when one sees all priors—even parametric ones—as measures on sets of densities as opposed to measures on finite-dimensional parameter spaces.     

Generalized piecewise linear histograms

We extend the concept of piecewise linear histogram introduced recently by Beirlant, Berlinet and Györfi. The disadvantage of that histogram is that in many models it takes on negative values with probability close to 1. We show that for a wide set of models, the extended class of estimates contains a bona fide density with probability tending to 1 as the sample size n increases to infinity. The mean integrated absolute error in the extended class of estimators decreases with the same rate n^–2/5 as in the original narrower class.     

Firm Density and Industry R & D Intensity: Theory and Evidence

By deriving a formal model of industry R & D that identifies factors influencing industry R & D intensity, this paper first suggests firm density, defined as the inverse of average firm sales or simply the number of firms divided by industry sales, as a measure of market structure that is appropriate in explaining industry R & D intensity. The model shows that the cost structure of R & D, consumer preference over quality and price, the appropriability of R & D, firm density, and the average level of firm R & D intensity jointly determine industry R & D intensity. In particular, firm density has a positive relationship with industry R & D intensity, implying that firms in higher firm-density industries feel fiercer competitive pressure and thus engage more intensively in R & D. An empirical analysis of panel data on industry R & D activities of Korean manufacturing industries during the period 1991–1996 provides supportive evidence for the predictions of the model including the positive relationship between firm density and industry R & D intensity. The theoretical model and the empirical results are also consistent with the recent survey of U.S. corporate R & D activities by the U.S. Department of Commerce and the National Science Foundation (1999).     

中国低密度住宅设计的工业化方向

针对中国城市低密度住宅现状,作者分析了其郊区化、大规模及平民化特征,提出“有人情味”的工业化将是低密度住宅在中国的发展方向。     

贸易结构、技术密度与经济增长——一个分析框架及基于中国数据的检验

以往的国际贸易理论都强调，贸易结构在促进经济增长方面起着重要作用。本文通过VAR模型估计了中国的贸易结构与经济增长的关系，结果显示，中国的贸易结构并不显著影响经济增长。     

大秦线增加资本投入提高运输密度的分析

资本投入对产出数量起决定性作用。通过对大秦线的资本投入对运量增加的影响情况进行分析,说明加强影响列车质量和密度相关设施的资本投入,对提高产出起到重要作用。同时指出对投向大秦线的资本,应向发展重载技术方面倾斜,能对大秦线运输能力的提高起持续性影响作用。     

Analysing Tax–Benefit Reforms Using Non‐Parametric Methods*

Static tax–benefit microsimulation models (MSMs) are widely used and well‐regarded tools for public policy analysis, but it is essential to use them very carefully. This paper focuses on the analysis of MSM output, suggesting the use of non‐parametric methods as a useful, informative and relatively straightforward complement to detect effects not always captured by measures often used to present MSM results. Non‐parametric methods are used here to analyse the output of an MSM applied to the 1998 Italian personal income tax reform, the main change in which concerned the tax schedule: the first tax rate was increased from 10 per cent to 18.5 per cent and the top one was reduced by 4.5 percentage points. Non‐parametric methods highlight that the effects of this reform were very different for different types of households, with low‐income pensioner households among the main losers. Results are checked for robustness by standard statistical methods and compared with empirical results obtainable using quintile histograms.     

区域增长极形成机制研究——以我国珠三角地区与香港为例

运用新经济增长理论和新经济地理理论的观点和模型探讨了区域增长极的形成机制,得出的结论是:区位的比较优势是增长极初步形成和分布的重要因素,经济活动密度在一定的递增区间内成为区域增长极经济和空间规模的主要内生增长源。这一结论既对廖什用市场密度来确定城市体系区位的方法提供了理论依据,又为区域经济的发展指出了一条以点轴经济系统带动区域经济一体化的有效途径。