陕西省龙草坪林业局森林碳汇价值评析

分析了森林碳汇的基础理论,阐述了森林碳汇价值的估算方法,对陕西省龙草坪林业局的森林碳汇进行了测算并展望了其意义及应用前景。研究可为评价森林生态效益、探讨森林碳汇融资提供理论依据和参考价值。     

高等教育能打破社会阶层固化吗?--基于有序probit半参数估计及夏普里值分解的实证分析

文章基于2013年中国综合社会调查(CGSS2013)数据,首先运用有序probit 模型的半参数估计方法检验高等教育对社会阶层的影响,其次采用最新发展的基于 R2的夏普里值方法测度高等教育对社会分层形成的贡献率,并从区域视角管窥经济发展和市场化转型条件下高等教育受影响的演进趋势。结果显示：(1)接受过高等教育的居民,确实拥有更高的社会阶层评估。但若剔除家庭背景带来的接受高等教育机会的差距,高等教育促进社会阶层流动的能力明显弱化。基于R2的夏普里值分解表明,高等教育变量的贡献率不到10%,撇去高等教育的代际传递效应后,净效应更低。(2)东部地区有微弱的证据显示高等教育带来的社会阶层提升效应正在展现。无论是从总贡献率还是分解后的直接贡献率看,东部地区的百分比贡献都要高于中西部地区。这说明随着经济发展和市场化改革的推进,高等教育改善社会分层的效果有可能会强化。(3)影响社会分层差异最重要的因素为家庭过去的社会阶层,即社会阶层分布存在明显的代际传递现象。另外,个体特征及经济特征也是影响社会分层的重要因素。文章研究显示,要进一步推进开放型社会阶层的形成,需要在构建市场化导向能力本位的新型社会流动体系制度框架下,确立更为公平的高等教育竞争机制及补偿机制。     

A new perspective on the exporter productivity premium: online trade

We use a unique firm-level data set including 9000 companies from 26 European Union countries covering four different sectors to take a close look at the relationship between online exports and productivity. The online exporter productivity premium is estimated using different techniques (ordinary least squares, quantile regressions and robust estimation). Results consistently indicate that the estimated online exporter productivity premium is statistically different from zero, positive and significant from an economic point of view. European online exporters, according to these results, are approximately 2% more productive than non-online exporters. Productivity differences between firms could be related to variables that are not included in the empirical model. More research would be needed to address this issue in the future.     

Asymptotic expansion of S-estimators of location and covariance

By means of a straightforward application of empirical process theory, we show that S-estimators of multivariate location and covariance are asymptotically equivalent to a sum of independent vector and matrix valued random elements respectively. This provides an alternative proof of asymptotic normality of S-estimators and clearly explains the limiting covariance structure. It also leads to a relatively simple proof of asymptotic normality of the length of the shortest α-fraction.     

Recovering Hicksian Consumer Surplus within a Collective Model: Hausman's Method for the Household

The purpose of this paper is to describe the implications of the collective model of household behavior for the methods used to estimate the economic value of non-marketed environmental resources. After demonstrating how the separability restrictions inherent in the collective model allow individual preference and household income allocation choices to be distinguished, the paper demonstrates how the framework can be used to recover Hicksian consumer surplus. An algebraic example is used to illustrate how the framework can be used in valuing environmental resources.     

Public spending,public governance and economic growth at the Vietnamese provincial level: A disaggregate analysis

This study examines the role of economic governance in the relationship between public spending, private investment, and economic growth in Vietnam at the provincial level. The study data consist of sixty-two Vietnamese provinces for the period 2006–2015. Some notable results are attained by applying a sequential (two-stage) estimation. First, the marginal benefits to economic growth of increased Vietnamese provincial government expenditures may be constrained because of the inefficiency of expenditures on education, business services, and public administration. Second, public spending and private investment are found to be substitutes at the provincial level. Third, based on the Provincial Competitiveness Index (PCI) ranking, used as a proxy for provincial public governance in Vietnam, the significance of public governance can be observed. The study concludes that good governance, characterized by different attributes, such as lower informal charges, greater transparency, and unbiased policy, plays a critical role in improving the impact of government expenditure on economic growth in Vietnamese provinces, particularly through its interactions with private sector investment.     

省域全要素生产率地区差异的动态演进

笔者在运用索洛余值法对我国各地区全要素生产率进行估算的基础上,利用非参数的核密度函数法和马尔可夫链法对全要素生产率地区差异的动态演进进行了分析。研究结果表明,我国各地区全要素生产率差异较大,从东部往西部呈现逐渐降低的梯度分布格局;各地区之间全要素生产率的绝对差距在20世纪80年代呈现缩小趋势,而从1990年以后呈现加速扩大趋势;同时,核密度函数分布呈现双峰收敛趋势,进一步表明全要素生产率两极分化现象严重;从马尔可夫链的稳态分布来看,各地区的全要素生产率将继续保持较大差异,短期内难以实现均衡发展。     

Accurate Short-Term Yield Curve Forecasting using Functional Gradient Descent

We propose a multivariate nonparametric technique for generatingreliable short-term historical yield curve scenarios and confidenceintervals. The approach is based on a Functional Gradient Descent(FGD) estimation of the conditional mean vector and covariancematrix of a multivariate interest rate series. It is computationallyfeasible in large dimensions and it can account for nonlinearitiesin the dependence of interest rates at all available maturities.Based on FGD we apply filtered historical simulation to computereliable out-of-sample yield curve scenarios and confidenceintervals. We back-test our methodology on daily USD bond datafor forecasting horizons from 1 to 10 days. Based on severalstatistical performance measures we find significant evidenceof a higher predictive power of our method when compared toscenarios generating techniques based on (i) factor analysis,(ii) a multivariate CCC-GARCH model, or (iii) an exponentialsmoothing covariances estimator as in the RiskMetrics^TM approach.     

叠加共轭对称训练序列的OFDM系统时频同步方法

针对正交频分复用（OFDM）系统对同步错误率和频率偏移敏感的问题,提出了一种叠加共轭对称训练序列的OFDM系统时间和频率同步方法。该同步方法将快速傅里叶逆变换（IFFT）调制后的序列构成具有共轭对称特性的训练序列,并叠加到OFDM数据符号上;在接收端,利用叠加训练序列和融合循环前缀信息来获取OFDM系统同步信息。理论分析和仿真表明：在信噪比为5 dB时,该同步算法定时同步正确概率已接近100%;在信噪比为4 dB时,频偏估计精度可以达到10-4;该同步算法不仅具有更好的同步性能,而且节省系统的有效带宽以及降低系统的计算法复杂度。     

成都市土地资源可持续利用评价

土地资源可持续利用评价是衡量土地资源是否达到合理利用的评判标准,是评价和监测土地可持续利用的状态和程度。本文从环境、资源、经济及社会四个准则层出发,选取 21个因素作为参评因子,建立评价指标体系;运用基于时点评价法、线性比例法与熵权法进行综合测算,对成都市土地资源可持续利用进行针对性的实践研究。结果表明,成都市土地可持续利用处于一般可持续利用状态,整体态势良好。但成都市土地利用的环境保护性还有待进一步加强,注重协调耕地与社会经济发展的关系,进一步提高耕地的土地利用效益。