Examination of the poverty-environmental degradation nexus in Sub-Saharan Africa

The relationship between environmental degradation and poverty has increasingly become the focus of national strategic decision-making in recent years.However,despite several theoretical explorations on the nexus,a dearth of empirical literature on the poverty-environmental degradation nexus,specifically on Sub-Saharan Africa(SSA),still exists.In this study,we investigated the poverty-environmental degradation nexus in SSA.We hypothesized that poverty is both a cause and effect of environmental degradation,and this relationship is explained as a vicious cycle.Unlike previous studies,we employed several alternative indicators of environmental degradation to examine the poverty-environmental degradation nexus in this study.We used data from 41 countries of SSA between 1996 and 2019 and employed the generalized method of moments(GMM)approach.The findings suggest a cyclical relationship between poverty and environmental degradation in SSA,which confirms that an increase in poverty leads to an increase in environmental degradation,especially in deforestation and PM2.5 emissions.Similarly,the increase in environmental degradation positively affects poverty in SSA.We also confirmed that exogenous conditioning factors such as population growth rate,education,industrialization,and income inequality,institutional quality indicators such as governance effectiveness,control of corruption,freedom ad civil liberty,and democracy,and endogenous factors including fossil fuel energy use,fuelwood energy use,household health expenditure,infant mortality rate,and agriculture productivity influence the nexus between poverty and environmental degradation.The findings on the relationship between poverty and environmental degradation in SSA are a testimonial evidence that both poverty and environmental degradation are significant issues in SSA.Hence,poverty alleviation policies in SSA should not lead to PM2.5 emissions and deforestation,which may as well force people into a poverty-environmental degradation trap.Instead,poverty reduction policies should simultaneously achieve environmental conservation.

新常态下产业结构变动与经济增长——基于省级动态面板数据的GMM方法

新常态下,正确处理好稳增长与调结构的关系,有重要的政策含义。文章通过构建NAV、MLI两个不同的产业结构变动指数,基于省级1993-2013年的面板数据,运用GMM方法进行了实证检验。结果表明:从全国范围来看,短期内,产业结构变动与经济增长之间存在双向格兰杰因果关系,而较长时期内,仅存在经济增长到产业结构变动的单向格兰杰因果关系。其次,从省级层面来看,产业结构变动与经济增长之间的格兰杰因果关系表现出很大的异质性。基于此结论,文章认为,产业政策并不具有较长时期有效性,产业政策的制定需要视期限、地区的不同而择机、择时制定;同时,要规避产业政策缺陷带来的不足,规避"结构负利"的出现。

城市水价预测模型研究与GMM参数校验

主要介绍城市水价预测边际成本方法数学模型及其广义二阶矩(GMM)估计的研究.将水价模型分割为可变成本函数与固定成本函数两部分,为了减小预测误差对每部分函数参数进行了GMM估计与校验.从水的供应与需求两个方面对水价数学模型进行了详细描述,并以我国某地区实际数据为样本对水价预测模型与GMM估计进行了应用;在水价预测模型中还以城市给水管网长度为规模参数,模拟了边际成本定价及其社会剩余变化对管网规模效应的影响.揭示了水价边际价格与边际成本之间的差异,以及城市给水管网规模效应范围及其与水价之间的敏感程度,表明了城市水价预测最优定价的特点.

欠发达地区金融发展与经济增长的实证研究:基于面板数据模型的GMM估计结果

当前,金融发展理论仍在不断深入、细化地向前发展。使用1998——2005年的截面数据考察股票市场和银行系统对欠发达地区经济增长的影响,同时利用广义矩(GMM)技术对动态面板数据进行估计。研究结果表明,在欠发达地区,由于股票市场规模的狭小,其对经济增长的影响不显著;银行体系在经济增长的过程中也没能有效地发挥其推动作用。金融总量不足、结构不合理以及金融机构治理结构混乱,制约了欠发达地区金融发展对经济增长的促进作用。

财政分权、税收竞争与制造业高质量发展——基于变异系数-系统GMM的估计

研究国内财政分权体制和地方政府税收竞争对制造业高质量发展的影响机理及其效应,对制造业高质量发展新路径的形成具有重要意义。文章在构建多维评价指标体系的基础上,依据中国30个省级行政区面板数据,对制造业高质量发展指数进行变异系数处理,并从财政收入分权和财政支出分权双重视角构建系统GMM估计模型,检验财政分权体制下税收总量竞争和税收结构竞争对制造业高质量发展的影响。结果表明:样本考察期内,中国制造业高质量发展指数呈“波浪式”上升趋势,2009-2015年中国制造业高质量发展指数较低,2016-2019年制造业高质量发展指数快速上升;整体上,财政分权与制造业高质量发展呈负相关关系;财政分权体制下,税收总量竞争显著抑制制造业高质量发展,增值税竞争促进制造业高质量发展,企业所得税竞争抑制制造业高质量发展。文章从优化财政分权体制、规范税收优惠政策、实行地区差异化税收政策等角度,提出提升制造业高质量发展的政策建议。

GMM方法在金融领域的发展与应用——2013年度诺贝尔经济学奖获得者拉尔斯·彼得·汉森学术贡献评述

基于诺贝尔经济学奖评审委员会的公报,2013年度诺贝尔经济学奖得主拉尔斯·彼得·汉森的学术贡献在于揭示了广义矩估计在经济学界方法论的开创性,以及其在金融资产定价领域的应用及延伸研究,开创性地检验了消费资本资产定价模型,推动了金融资产定价理论的发展。广义矩估计方法因其一般性及普适性,在金融计量和市场微观经济等领域应用尤其广泛,并拓展至宏观经济学领域。目前,该方法在我国金融领域的应用研究远不及国外文献成熟,存在方法论难度较大、模型适用性有待考察、方法能否正确使用等因素。

带常数项的向量误差校正模型的GMM估计方法

将Quintos研究的一类不带常数项的协整向量的GMM估计推广到带常数项的协整向量的GMM估计 ,利用Johansen的降秩估计法得到了参数的估计、渐近性分布。文中所得的结论包括了Johansen和Quintos两文中的结论。

Small Sample Estimation in Dynamic Panel Data Models: A Simulation Study

We used simulated data to investigate both the small and large sample properties of the within-groups (WG) estimator and the first difference generalized method of moments (FD-GMM) estimator of a dynamic panel data (DPD) model. The magnitude of WG and FD-GMM estimates are almost the same for square panels. WG estimator performs best for long panels such as those with time dimension as large as 50. The advantage of FD-GMM estimator however, is observed on panels that are long and wide, say with time dimension at least 25 and cross-section dimension size of at least 30. For small-sized panels, the two methods failed since their optimality was established in the context of asymptotic theory. We developed parametric bootstrap versions of WG and FD-GMM estimators. Simulation study indicates the advantages of the bootstrap methods under small sample cases on the assumption that variances of the individual effects and the disturbances are of similar magnitude. The boostrapped WG and FD-GMM estimators are optimal for small samples.

中国被诉反倾销寒蝉效应分析——基于引力模型的系统GMM估计

基于2001~2011年国外反倾销面板案件数据，构造以同期对华反倾销最多的27个国家或地区为截面的动态面板数据模型，应用系统GMM模型实证分析国外对华反倾销对中国总出口的影响。结果显示。国外对华反倾销调查并没有抑制中国出口，而反倾销措施对中国总出口有明显的负面影响。总的来看，国外对华反倾销使得中国总出口明显下降，中国被诉反倾销寒蝉效应显著存在。

The mechanism and heterogeneity of environmental regulations'impact on the technological progress of dairy farming

The study analyses the theoretical mechanism through which environmental regulation affects the dairy industry’s technological progress,with a particular focus on how the effect is conditional on farm size.Using the input–output data of dairy farms of different sizes from 2009 to 2019 in 10 Chinese provinces/autonomous regions in China and the quantitative measurement index of environmental regulation,the study estimates environmental regulation’s heterogeneous influences on the dairy industry’s technological progress by dynamic panel data models.The empirical results suggest that,first,environmental regulation has a U-type influence on the technological progress of dairy farming.The U-type influence means moving from pollution control’s high cost and low technology progress to the high profit and high innovation input generated by optimizing the breeding structure.Second,the promotion of dairy farming technology depends on farm size.The effect of environmental regulation on technological progress in moderately large-farms showed a U-type relationship.In contrast,the effect in free-range and large-size dairy farms showed a linear and positive relationship.The government should further strengthen environmental regulation based on advancing moderately large-farms in compliance with market mechanisms in the long run.Particular attention should be paid to the forms of environmental regulation so that dairy cattle breeding technology can break through the inflection point of the“U”curve as soon as possible and ensure the significance of the rising stage.Along the way,technical support should be provided for realizing environmental protection and economic growth.

Parametric and Non-Parametric Survival Analysis of Patients with Acute Myeloid Leukemia (AML)

Background: Acute Myeloid leukemia (AML) is the most prominent acute leukemia in adults. In the United States, we experience over 20,000 cases per year. Over the past decade, improvements in the diagnosis of subtypes of AML and advances in therapeutic approaches have improved the outlook for patients with AML. However, despite these advancements, the survival rate among patients who are less than 65 years of age is only 40 percent. Purpose: The purpose of the paper is to study if there exists any significant difference in the survival probabilities of male and female AML patients. Also, we want to investigate if there is any parametric probability distribution that best fits the male and female patient survival and compare the survival probabilities with the non-parametric Kaplan-Meier (KM) method. Methods: We used both parametric and non-parametric statistical methods to perform the survival analysis to assess the survival probabilities of 2015 patients diagnosed with AML. Results: We found evidence of a statistically significant difference between the mean survival time of male and female patients diagnosed with AML. We performed parametric survival analysis and found a Generalized Extreme Value (GEV) distribution best fitting the data of the survival time for male and female patients. We then estimated the survival probabilities and compared them with the frequently used non-parametric Kaplan-Meier (KM) survival method. Conclusion: The comparison between the survival probability estimates of the two methods revealed a better survival probability estimate by the parametric method than the Kaplan-Meier. We also compared the median survival time of male and female patients individually with descriptive, parametric, and non-parametric methods of analysis. The parametric survival analysis is more robust and efficient because it is based on a well-defined parametric probabilistic distribution, hence preferred over the non-parametric Kaplan-Meier estimate. This study offers therapeutic significance for further enhancement to treat patients with Acute Myeloid Leukemia.

数字经济驱动全国商品统一大市场建设的机理与路径

建设全国统一大市场是加快构建新发展格局的基础支撑和内在要求,是构建高水平社会主义市场经济体制的关键之举。全国商品统一大市场是全国统一大市场的重要组成部分。以数字经济驱动全国商品统一大市场建设是数字经济时代的重要举措。从机理和现实看,数字经济可以突破时空和信息非对称性限制,与传统产业深度融合,重构实体经济,加速实现供需平衡,畅通国内大循环,进而驱动全国商品统一大市场建设。由于各地数字经济发展基础不同,地区间出现了数字鸿沟。同时,“大数据杀熟”“竞价排名”等新型垄断手段对价格机制具有破坏性,会弱化数字经济的驱动作用。基于2016—2020年我国省级面板数据,利用静态和动态面板数据模型进行实证研究发现,当前我国数字经济能显著驱动全国商品统一大市场建设。数字经济驱动全国商品统一大市场建设的实现路径有三:一是推动区域数字经济协调发展,缩小地区间数字鸿沟;二是加快流通业数字化转型,强化流通体系支撑作用;三是提升政府数字经济治理能力,提高数字经济规制效率。

数字普惠金融赋能乡村全面振兴

要想在数字时代的大背景下推动乡村全面振兴,实现乡村高质量发展,势必需要借助数字金融工具。因此,研究数字普惠金融能否推动乡村全面振兴具有较强的理论和现实意义。本文分别构建静态面板模型和动态面板模型对数字普惠金融与乡村全面振兴之间的关系进行实证研究。研究发现,数字普惠金融发展对乡村振兴的影响呈现非线性特征,二者之间存在先抑制后促进的“U”形关系;现阶段数字普惠金融发展已越过极值点,其发展确实能够促进乡村全面振兴。通过剔除直辖市样本、替换核心解释变量进行稳健性检验后,该结论依然成立。异质性分析显示,在高人口水平地区,二者之间显著存在“U”形关系,数字普惠金融发展对乡村全面振兴具有更强推动作用。本文研究为数字普惠金融与乡村振兴之间的关系认定提供了新的理论依据,为我国推动乡村全面振兴提供了路径支持,并且为实现乡村经济高质量发展制定更为匹配的金融政策提供良好参考。

都市圈促进区域共同富裕研究——以成渝地区双城经济圈为例

都市圈的发展对于实现区域共同富裕至关重要。文章以成渝地区双城经济圈为例,测算共同富裕发展水平指数,分析成渝地区双城经济圈共同富裕的区域差异,实证检验了共同富裕的收敛特征。结果发现:成渝地区双城经济圈共同富裕不具有明显的σ收敛特点,但存在绝对β收敛和条件β收敛的事实;都市圈建设会加速共同富裕的收敛进程;都市圈建设在加速共同富裕的收敛进程中存在显著的差异性,都市圈建设对成都平原城市群共同富裕的加速效果最为明显,川南地区的正向影响较弱,川东北地区对共同富裕的影响最弱。

Hierarchical parameter estimation of DFIG and drive train system in a wind turbine generator

A new hierarchical parameter estimation method for doubly fed induction generator （DFIG） and drive train system in a wind turbine generator （WTG） is proposed in this paper. Firstly, the parameters of the DFIG and the drive train are estimated locally under different types of disturbances. Secondly, a coordination estimation method is further applied to identify the parameters of the DFIG and the drive train simultaneously with the purpose of attaining the global optimal estimation results. The main benefit of the proposed scheme is the improved estimation accuracy. Estimation results confirm the applicability of the proposed estimation technique.

人口老龄化与碳排放强度——基于劳动供给的中介效应与遮掩效应

基于2003—2020年省际面板数据,运用固定效应模型、动态GMM(广义矩估计)模型分析人口老龄化与碳排放强度之间的关系,应用中介效应模型分析劳动年龄人口、劳动生产率、劳动力质量、劳动参与率在人口老龄化与碳排放强度之间的作用路径。研究结果表明:人口老龄化与碳排放强度之间呈倒“U”形关系;样本期内,劳动年龄人口中介效应不显著;劳动生产率、劳动力质量具有部分中介效应;男性劳动参与率、女性劳动参与率具有遮掩效应。

农产品国际贸易与价格变动对农民收入的影响——基于28个省域面板数据的分析

实现农民增收是解决“三农”问题的核心,也是维护农村社会稳定、构建新发展格局的有力支撑。在对外开放新格局不断拓宽的背景下,分析农产品国际贸易与农民收入之间的关系有较大理论和现实意义。中国是农产品国际贸易大国,农产品进出口贸易会影响农民收入并以价格信号传导。以2002—2020年中国28个省(直辖市)相关数据为样本对农产品进出口额、农产品价格和农民收入三者关系进行实证分析。结果表明农产品出口可以促进农民增收,农产品进口虽然对农民收入有正向作用但存在地区异质性;农产品出口对中低收入农民群体的增收作用较大,进口则相反;价格变动是农产品国际贸易影响农民收入的中介变量。因此,建议扩大优势农产品出口并适当调节农产品进口;鼓励农户适度规模经营实现多渠道增收;保持国内农产品市场稳定并提高其市场化程度,最大限度发挥市场机制和价格信号的作用。

金融发展影响能源消费结构吗?--跨国经验分析

金融发展经常被认为是经济增长的一个重要推动因素。同样的,金融发展也可能会影响能源需求。金融发展可以通过促进金融系统发展、带动经济增长并促进产业结构调整这样的传导途径,使能源消费结构发生变动。本文对全球55个国家23年(1985～2007)的面板数据库的研究发现,金融发展的确会影响能源消费与需求,进而影响能源消费结构的变动。实证结果表明,金融发展会促进"化石燃料"能源和替代能源消费的增加,减少可再生能源的消费,对能源消费结构的改善有着一定的促进作用。所以,在制定能源相关政策和对高能耗部门进行产业调整时,要考虑金融发展的影响。

雷击风机时叶片和塔筒对接地装置冲击接地特性的影响

风机接地装置的冲击接地特性评估方法目前仍缺少指导规范。实际雷击中雷电流在经过叶片和塔筒时会在其中形成波过程,对接地装置的冲击接地电阻和地电位升(GPR)产生影响。为此,通过矩量法和Fouier变换的仿真计算,探讨了在不同叶片和塔筒总高度、不同土壤电阻率、不同接地装置尺寸和不同雷电流波形的情况下,在风机遭遇雷电流时叶片和塔筒对接地装置冲击接地特性的影响,并运用波过程理论对影响机理进行了分析。通过计算可以发现,由于在风机遭遇雷电流时叶片和塔筒中雷电流波会发生折反射,所以实际地电位升会出现振荡,从而会对接地装置的冲击接地电阻产生影响。

地方政府竞争对环境污染影响效应的实证研究

基于中国1998—2012年省际动态面板数据和通过改进后熵值法计算得到的环境污染综合指数,运用系统广义矩估计(GMM)实证地方政府竞争对环境污染的影响效应。结果表明:地方政府竞争对环境污染呈显著的正向影响,即地方政府竞争显著增加了地区污染排放,降低了区域环境质量。而经济发展水平、资本存量与环境污染均呈倒"U"形关系,经济发展短期会带来环境污染,长远则有助于环境质量的改善;资本存量决定了一个地方的投资能力,投资速度过猛或滞后均会给环境造成影响。认为,应从改革传统政绩考核办法、确立地方政府环境责任制度等方面优化地方政府竞争机制;并进一步加大地方政府环境治理投资力度,着力解决环境污染问题,从而提高环境质量。