This paper takes global manufacturing listed companies from 2010 to 2022 as samples and uses the difference-in-differences(DID)method to empirically examine the impact of the internationalization of ESG standards on t...This paper takes global manufacturing listed companies from 2010 to 2022 as samples and uses the difference-in-differences(DID)method to empirically examine the impact of the internationalization of ESG standards on the trade competitiveness of multinational enterprises and their mechanisms.The research finds that the internationalization of ESG standards significantly enhances the trade competitiveness of multinational manufacturing enterprises,and this effect is dynamic and sustainable.The mechanism analysis indicates that the internationalization of ESG standards exerts its influence through three pathways:reducing enterprise financing costs,promoting technological innovation,and enhancing brand reputation.The heterogeneity analysis shows that this effect is more significant in enterprises from developed countries,high-pollution industries,and larger enterprises.This paper provides micro-level evidence for understanding the economic consequences of the internationalization of ESG standards and offers policy implications for multinational enterprises to cope with the global ESG rule changes and enhance their trade competitiveness.展开更多
The cumulative expression of multistage deformation is complex multiperiod fractures,which are commonly seen in tectonic zones.The Middle Triassic Leikoupo Formation in the western Sichuan Basin Depression,China,is a ...The cumulative expression of multistage deformation is complex multiperiod fractures,which are commonly seen in tectonic zones.The Middle Triassic Leikoupo Formation in the western Sichuan Basin Depression,China,is a typical marine carbonate reservoir with natural fractures caused mainly by tectonic movements.According to outcrops,drill cores,image logging,and fluid inclusions,the fracture characteristics,types of natural fractures,and interactions of fractures are determined.In total,419 natural fractures in 493.2 m of cores from 7 wells are investigated,which are mainly shear and tensile fractures with a small number of weathering generated fractures.Meanwhile,the results of the stable isotope analysis of δ13C and δ18O,as well as the flow fluid inclusion data,reveal four tectonic periods of fractures with different occurrences.Based on the history of regional tectonic evolution,indicating one period of weathering fractures ascribable to stratal uplift and three periods of structural fractures related to the sequential tectonic movements of the Longmenshan fault belt.By analyzing the interaction relationships of fractures,three types of fracture interaction relationships are observed:cutting,restraining,and overlapping.The four stages fractures are chronologically assigned to(1)the early Indosinian N-S trending compression,(2)the late Indosinian NW-SE compression,(3)the middle Yanshanian NE-SE compression,and(4)the early Himalayan E-W compression.The influence of natural fractures on gas migration and well production in marine carbonates is discussed,and indicates that tectonic fractures could provide seepage channels for gas migration and accumulation from near or distant hydrocarbon source rocks into the Middle Triassic Leikoupo Formation.This study utilizes a pragmatic approach for understanding the fracture genesis mechanism in oil and gas field with multiperiod fractures.展开更多
Purpose:In recent decades,with the availability of large-scale scientific corpus datasets,difference-in-difference(DID)is increasingly used in the science of science and bibliometrics studies.DID method outputs the un...Purpose:In recent decades,with the availability of large-scale scientific corpus datasets,difference-in-difference(DID)is increasingly used in the science of science and bibliometrics studies.DID method outputs the unbiased estimation on condition that several hypotheses hold,especially the common trend assumption.In this paper,we gave a systematic demonstration of DID in the science of science,and the potential ways to improve the accuracy of DID method.Design/methodology/approach:At first,we reviewed the statistical assumptions,the model specification,and the application procedures of DID method.Second,to improve the necessary assumptions before conducting DID regression and the accuracy of estimation,we introduced some matching techniques serving as the pre-selecting step for DID design by matching control individuals who are equivalent to those treated ones on observational variables before the intervention.Lastly,we performed a case study to estimate the effects of prizewinning on the scientific performance of Nobel laureates,by comparing the yearly citation impact after the prizewinning year between Nobel laureates and their prizewinning-work coauthors.Findings:We introduced the procedures to conduct a DID estimation and demonstrated the effectiveness to use matching method to improve the results.As a case study,we found that there are no significant increases in citations for Nobel laureates compared to their prizewinning coauthors.Research limitations:This study ignored the rigorous mathematical deduction parts of DID,while focused on the practical parts.Practical implications:This work gives experimental practice and potential guidelines to use DID method in science of science and bibliometrics studies.Originality/value:This study gains insights into the usage of econometric tools in science of science.展开更多
A complex autonomous inventory coupled system is considered. It can take, for example, the form of a network of chemical or biochemical reactors, where the inventory interactions perform the recycling of by-products b...A complex autonomous inventory coupled system is considered. It can take, for example, the form of a network of chemical or biochemical reactors, where the inventory interactions perform the recycling of by-products between the subsystems. Because of the flexible subsystems interactions, each of them can be operated with their own periods utilizing advantageously their dynamic properties. A multifrequency second-order test generalizing the p-test for single systems is described. It can be used to decide which kind of the operation (the static one, the periodic one or the multiperiodic one) will intensify the productivity of a complex system. An illustrative example of the multiperiodic optimization of a complex chemical production system is presented.展开更多
Coal dependence and inefficient decentralized heating have significantly increased China’s energy consumption for winter heating,increasing air pollution and exacerbating the greenhouse effect.In 2017,China implement...Coal dependence and inefficient decentralized heating have significantly increased China’s energy consumption for winter heating,increasing air pollution and exacerbating the greenhouse effect.In 2017,China implemented the Pilot Policy on Clean Winter Heating in Northern China,aiming to achieve high central heating coverage and cleaner energy consumption.Studying the effects of this policy can help promote its implementation and serve as a reference for effective adjustment of the contents in the future.However,few studies have investigated this policy and its carbon reduction effects,and most focus on the provincial or city levels.Therefore,this paper considers the policy’s influence on air pollution and carbon emissions at the county level to provide a precise and comprehensive assessment of the policy effects.We use panel data from 1290 counties in 15 provinces in Northern China from 2014 to 2021,applying a multiperiod difference-in-differences model to quantify the impact of the policy on carbon emissions and air quality in the pilot area.We then conduct a series of tests to demonstrate the robustness of the results and analyze the mechanisms of the policy effects from two perspectives,namely,central heating and natural gas use,through a mediating effect model.Finally,we examine the heterogeneity of policy effects between counties based on geographic location and per capita income levels of rural residents through a moderating effect model.The results reveal that the policy significantly reduces air pollution and carbon emissions in the pilot area by increasing the central heating area and natural gas use.Compared with the central and western regions in the north and areas with low-income rural residents,the policy effects in the eastern regions in the north and areas with high-income rural residents are more pronounced.展开更多
As urbanization accelerates globally,air pollution-particularly PM_(2.5)-is becoming an increasingly significant threat,not only to public health but also the environment.In-depth research on the impact of China’s Ze...As urbanization accelerates globally,air pollution-particularly PM_(2.5)-is becoming an increasingly significant threat,not only to public health but also the environment.In-depth research on the impact of China’s Zero Waste City pilot policy on PM_(2.5)concentration offers valuable insights into the policy’s effectiveness and provides a potential model for environmental governance worldwide.This study employs panel data from 293 Chinese cities from 2014 to 2022 to systematically analyze the impact of the Zero-Waste City policy on PM_(2.5)concentration using a difference-in-differences model.The findings indicate that the policy not only directly reduces PM_(2.5)concentration but also indirectly curbs PM_(2.5)emissions by enhancing green innovation and green economic efficiency.Moreover,the policy’s effects are found to be positively moderated by urban energy dependence and digital financial inclusion,while they are negatively moderated by the government debt ratio.Based on these findings,this study suggests that cities should actively develop their digital economy,reduce government debt,promote green innovation,and improve green economic efficiency,as doing so will enhance their implementation of environmental policies and promote sustainable urban development.展开更多
为帮助企业更好地适应现实业务中的动态环境,研究了运输价格不确定性的多时段多式联运路径与存储协同优化模型。首先,在运输价格确定的环境下建立整数规划数学模型。其次,在运输价格不确定的环境下建立鲁棒优化模型,并将鲁棒优化模型转...为帮助企业更好地适应现实业务中的动态环境,研究了运输价格不确定性的多时段多式联运路径与存储协同优化模型。首先,在运输价格确定的环境下建立整数规划数学模型。其次,在运输价格不确定的环境下建立鲁棒优化模型,并将鲁棒优化模型转化为等价的线性鲁棒对等问题。随后,在传统k-短路算法、迭代贪婪(iterative greedy,IG)算法和自适应大邻域搜索算法(adaptive large neighbourhood search,ALNS)的基础上,提出了混合启发式算法MKIGALNS求解。最后,通过不同规模的算例实验,验证了所提出模型的正确性以及算法的有效性。实验结果表示,在10组算例中,不允许存储时的平均总运营成本为439191元,允许存储时的平均总运营成本为391378元,因此应当进行存储决策,有利于运营成本的降低。鲁棒实验结果表明,随着不确定预算取值的变化,总运营成本以及多时段多式联运运营策略发生变化,揭示了其内在联系。展开更多
Based on personality trait theory and experiential learning theory,lots of studies have revealed a reverse causal relationship between volunteering and the non-cognitive abilities of college students.Using data from a...Based on personality trait theory and experiential learning theory,lots of studies have revealed a reverse causal relationship between volunteering and the non-cognitive abilities of college students.Using data from a longitudinal survey of college students in Hunan Province,China,this study employed the difference-in-differences method to examine the causal relationship between volunteering and non-cognitive abilities,aiming to determine whether volunteering screens or cultivates the non-cognitive abilities of college students.The findings confirmed the screening effect of volunteering on extraversion and conscientiousness and the cultivating effect on agreeableness.However,there was neither a screening effect nor a cultivating effect on emotional stability and openness.It is indicated that volunteering during college primarily screens the non-cognitive abilities of students through personality trait mechanisms,with a limited cultivating effect on non-cognitive abilities.This highlights the necessity to prompt a re-evaluation of how volunteering fulfills its educational function.展开更多
Amid China’s rapid economic growth,significant regional imbalances persisted.To address this disparity,it is essential to pursue high-quality development by fostering endogenous drivers within poverty-stricken areas....Amid China’s rapid economic growth,significant regional imbalances persisted.To address this disparity,it is essential to pursue high-quality development by fostering endogenous drivers within poverty-stricken areas.In late 2011,the Chinese government introduced a new nationwide regional poverty alleviation and development program.This study examines the macroeconomic impacts and micro-level mechanisms of these policies by leveraging manually compiled policy documents and macro and micro data(county economies,enterprises,and land transactions),using a DID approach.The findings reveal that the program significantly boosted economic growth in poor regions without causing negative spillovers to neighboring or paired-assistance areas.Economic growth in the assisted regions was primarily driven by industrialization,encompassing both scale expansion and efficiency gains.A cost-benefit analysis further confirms substantial economic returns and long-term fiscal sustainability.These results provide important policy implications for refining regional poverty policies and advancing balanced development.展开更多
This study proposes a regression-based estimation method in difference-in-differences settings in the presence of time-varying covariates-a scenario commonly encountered in applications.We impose only a conditional pa...This study proposes a regression-based estimation method in difference-in-differences settings in the presence of time-varying covariates-a scenario commonly encountered in applications.We impose only a conditional parallel trends assumption with timevarying covariates and plausible assumptions on the conditional expectation functions.We show that a family of causal effect parameters is exactly the coefficient estimators from our proposed regressions even in the presence of staggered treatment timing and treatment effect heterogeneity across cohorts,time periods,and covariates.These parameters can be further aggregated to the dynamic treatment effects and the overall effect of being treated.We establish the corresponding asymptotic properties.Simulation studies suggest that our proposed regression-based estimators successfully outperform in estimating the causal parameters.Finally,we apply this method to evaluate the effect of intrastate bank deregulation on income inequality in the United States in the setting of Beck et al.(2010).We find substantially different results based on our proposed method.展开更多
The green credit policy(GCP)is an essential financial policy tool for solving the problem of environmental pollution,and urban energy conservation is an effective way to achieve the goal of carbon neutrality.However,e...The green credit policy(GCP)is an essential financial policy tool for solving the problem of environmental pollution,and urban energy conservation is an effective way to achieve the goal of carbon neutrality.However,existing research has not verified the energy-saving effects of green credit(GC)at the city level.Based on panel data from 283 cities in China,this study aims to investigate whether GC can effectively reduce urban energy intensity(EI),which is an important complement to existing research.In terms of research methods,to better evaluate the effect of the policy and exclude the influence of other relevant factors,this study considers the promulgation of the Green Credit Guideline(GCG)in 2012 as the basic event,uses the difference-in-differences(DID)model to investigate the impact of GC on EI,and discusses the main impact mechanism.The key results are follows.(1)GC can effectively reduce urban EI.(2)Public environmental demand positively regulates the negative correlation between GC and EI.(3)GC reduces EI through three main channels:government support,capital investment,and technological innovation;however,the mechanism of industrial structure has no significant effect.(4)The effect of GC is more significant in areas with large urban scales,low environmental regulation intensity,and high industrial agglomeration.Based on the above results,this study presents puts forward targeted policy recommendations to strengthen the role of GC in urban sustainable development.展开更多
Drawing on local legitimacy theory,which posits that firms seek acceptance and approval from their local community and stakeholders,we examine the effect of corporate governance(CG)quality on corporate social responsi...Drawing on local legitimacy theory,which posits that firms seek acceptance and approval from their local community and stakeholders,we examine the effect of corporate governance(CG)quality on corporate social responsibility(CSR)activities in Korea.Enhancing CG quality and engaging in CSR activities are increasingly important for firms’long-term sustainability.Using the KEJI-CSR index and the KCGS CG score,we find that CG quality positively influences CSR activities.Specifically,if the CG quality score increases by one standard deviation,CSR improves by approximately 1.6–2.3%of the mean CSR score.Furthermore,the relationship between CG and CSR is stronger for business conglomerates(chaebol-affiliated firms),suggesting that sound CG practices can promote CSR activities more effectively when the interests of management and stakeholders are better aligned.This finding supports local legitimacy theory.Our findings are robust under various tests,including difference-in-differences analysis and propensity score matching.An interesting policy implication is that multinational enterprises or foreign investors should prioritize the CG quality of their local subsidiaries or investee firms.Better CG practices can enhance CSR activities,which are essential for long-term survival in local markets.This study,however,is limited to Korea and may not be generalizable to other emerging markets with different governance structures.展开更多
Long-term exposure to fine particulate matters(PM_(2.5))has been associated with respiratory and cardiovascular diseases and the burden are potentially higher in China experiencing heavy air pollution.In this study,we...Long-term exposure to fine particulate matters(PM_(2.5))has been associated with respiratory and cardiovascular diseases and the burden are potentially higher in China experiencing heavy air pollution.In this study,we established the exposure-response association between long-term exposures to PM_(2.5)and lung function and blood pressure in Chinesemiddle-aged and older adults using linearmixed-effects and generalized additive mixedmodels based on 3 waves longitudinal health outcomes data by enrolling 19,988 participants from 121 cities across themainland of China.We also assessed the effect of Clean Air Policy(CAP)based on a quasi-experimental difference-in-differences(DID)design.A 10μg/m^(3)increase in PM_(2.5)concentration was associated with a 7.18(95%confidence interval[CI]:-8.35,-6.02)L/min decrease in PEF(peak expiratory flow)and a 0.72(95%[CI]:0.53,0.90)and a 0.30(95%[CI]:0.18,0.42)mmHg increase in systolic and diastolic blood pressure,respectively.The associations were more pronounced in males and rural areas for PEF,but similar across subgroups for blood pressure.DID results suggested that the effect of CAP on health outcomes were sensitive tomagnitudes of reduction in PM_(2.5).A 5μg/m^(3)reduction in PM_(2.5)or more generally led to 18.70(95%[CI]:0.79,36.61)higher PEF and-2.05(95%[CI]:-3.87,-0.23)lower diastolic blood pressure,respectively,compared to no reduction or increase in exposure.However,the effects were significant only in rural areas.Our analysis support CAP aiming to benefit public health and provides insights to inform future control policy for efficiently decreasing air pollution exposure burden.展开更多
Environmental protection policies(EPPs)play a pivotal role in advancing sustainable development and maintaining ecological balance by establishing clear directives and standards.However,a comprehensive methodology to ...Environmental protection policies(EPPs)play a pivotal role in advancing sustainable development and maintaining ecological balance by establishing clear directives and standards.However,a comprehensive methodology to evaluate the effectiveness of these policies remains underdeveloped.Here,we employ a difference-in-differences(DID)approach to assess the effectiveness of EPPs,using the implementation of the Resident Work(RW)policy as a quasi-natural experiment.Drawing on urban-level panel data from the Yangtze River Basin between 2016 and 2021,we demonstrate that the DID model robustly evaluates the RW policy's impact on water quality improvement.Cities that adopted the RW policy experienced a 0.0098 reduction in water pollution compared to non-adopting cities.A dynamic analysis revealed progressive water quality improvements over time,with stronger effects observed in economically disadvantaged cities.Furthermore,higher policy evaluation scores correlated with greater improvements in water quality.This study highlights the utility of the DID model in quantifying EPP effectiveness and offers a scalable framework for policy evaluation in environmental management.展开更多
文摘This paper takes global manufacturing listed companies from 2010 to 2022 as samples and uses the difference-in-differences(DID)method to empirically examine the impact of the internationalization of ESG standards on the trade competitiveness of multinational enterprises and their mechanisms.The research finds that the internationalization of ESG standards significantly enhances the trade competitiveness of multinational manufacturing enterprises,and this effect is dynamic and sustainable.The mechanism analysis indicates that the internationalization of ESG standards exerts its influence through three pathways:reducing enterprise financing costs,promoting technological innovation,and enhancing brand reputation.The heterogeneity analysis shows that this effect is more significant in enterprises from developed countries,high-pollution industries,and larger enterprises.This paper provides micro-level evidence for understanding the economic consequences of the internationalization of ESG standards and offers policy implications for multinational enterprises to cope with the global ESG rule changes and enhance their trade competitiveness.
基金The first,second,and fifth authors acknowledge the financial support provided by the National Natural Science Foundation of China(41672133)The second author also acknowledges the National Natural Science Foundation of China(4207021285).
文摘The cumulative expression of multistage deformation is complex multiperiod fractures,which are commonly seen in tectonic zones.The Middle Triassic Leikoupo Formation in the western Sichuan Basin Depression,China,is a typical marine carbonate reservoir with natural fractures caused mainly by tectonic movements.According to outcrops,drill cores,image logging,and fluid inclusions,the fracture characteristics,types of natural fractures,and interactions of fractures are determined.In total,419 natural fractures in 493.2 m of cores from 7 wells are investigated,which are mainly shear and tensile fractures with a small number of weathering generated fractures.Meanwhile,the results of the stable isotope analysis of δ13C and δ18O,as well as the flow fluid inclusion data,reveal four tectonic periods of fractures with different occurrences.Based on the history of regional tectonic evolution,indicating one period of weathering fractures ascribable to stratal uplift and three periods of structural fractures related to the sequential tectonic movements of the Longmenshan fault belt.By analyzing the interaction relationships of fractures,three types of fracture interaction relationships are observed:cutting,restraining,and overlapping.The four stages fractures are chronologically assigned to(1)the early Indosinian N-S trending compression,(2)the late Indosinian NW-SE compression,(3)the middle Yanshanian NE-SE compression,and(4)the early Himalayan E-W compression.The influence of natural fractures on gas migration and well production in marine carbonates is discussed,and indicates that tectonic fractures could provide seepage channels for gas migration and accumulation from near or distant hydrocarbon source rocks into the Middle Triassic Leikoupo Formation.This study utilizes a pragmatic approach for understanding the fracture genesis mechanism in oil and gas field with multiperiod fractures.
基金This work was supported by grants from the National Natural Science Foundation of China,with No.NSFC62006109 and NSFC12031005.
文摘Purpose:In recent decades,with the availability of large-scale scientific corpus datasets,difference-in-difference(DID)is increasingly used in the science of science and bibliometrics studies.DID method outputs the unbiased estimation on condition that several hypotheses hold,especially the common trend assumption.In this paper,we gave a systematic demonstration of DID in the science of science,and the potential ways to improve the accuracy of DID method.Design/methodology/approach:At first,we reviewed the statistical assumptions,the model specification,and the application procedures of DID method.Second,to improve the necessary assumptions before conducting DID regression and the accuracy of estimation,we introduced some matching techniques serving as the pre-selecting step for DID design by matching control individuals who are equivalent to those treated ones on observational variables before the intervention.Lastly,we performed a case study to estimate the effects of prizewinning on the scientific performance of Nobel laureates,by comparing the yearly citation impact after the prizewinning year between Nobel laureates and their prizewinning-work coauthors.Findings:We introduced the procedures to conduct a DID estimation and demonstrated the effectiveness to use matching method to improve the results.As a case study,we found that there are no significant increases in citations for Nobel laureates compared to their prizewinning coauthors.Research limitations:This study ignored the rigorous mathematical deduction parts of DID,while focused on the practical parts.Practical implications:This work gives experimental practice and potential guidelines to use DID method in science of science and bibliometrics studies.Originality/value:This study gains insights into the usage of econometric tools in science of science.
文摘A complex autonomous inventory coupled system is considered. It can take, for example, the form of a network of chemical or biochemical reactors, where the inventory interactions perform the recycling of by-products between the subsystems. Because of the flexible subsystems interactions, each of them can be operated with their own periods utilizing advantageously their dynamic properties. A multifrequency second-order test generalizing the p-test for single systems is described. It can be used to decide which kind of the operation (the static one, the periodic one or the multiperiodic one) will intensify the productivity of a complex system. An illustrative example of the multiperiodic optimization of a complex chemical production system is presented.
基金supported by the National Social Science Fund of China[Grant No.21BGL181]to Yan Chen.
文摘Coal dependence and inefficient decentralized heating have significantly increased China’s energy consumption for winter heating,increasing air pollution and exacerbating the greenhouse effect.In 2017,China implemented the Pilot Policy on Clean Winter Heating in Northern China,aiming to achieve high central heating coverage and cleaner energy consumption.Studying the effects of this policy can help promote its implementation and serve as a reference for effective adjustment of the contents in the future.However,few studies have investigated this policy and its carbon reduction effects,and most focus on the provincial or city levels.Therefore,this paper considers the policy’s influence on air pollution and carbon emissions at the county level to provide a precise and comprehensive assessment of the policy effects.We use panel data from 1290 counties in 15 provinces in Northern China from 2014 to 2021,applying a multiperiod difference-in-differences model to quantify the impact of the policy on carbon emissions and air quality in the pilot area.We then conduct a series of tests to demonstrate the robustness of the results and analyze the mechanisms of the policy effects from two perspectives,namely,central heating and natural gas use,through a mediating effect model.Finally,we examine the heterogeneity of policy effects between counties based on geographic location and per capita income levels of rural residents through a moderating effect model.The results reveal that the policy significantly reduces air pollution and carbon emissions in the pilot area by increasing the central heating area and natural gas use.Compared with the central and western regions in the north and areas with low-income rural residents,the policy effects in the eastern regions in the north and areas with high-income rural residents are more pronounced.
基金The authors declare that fund support was received from National Social Science Fund of China[Grant No.23BJL010].
文摘As urbanization accelerates globally,air pollution-particularly PM_(2.5)-is becoming an increasingly significant threat,not only to public health but also the environment.In-depth research on the impact of China’s Zero Waste City pilot policy on PM_(2.5)concentration offers valuable insights into the policy’s effectiveness and provides a potential model for environmental governance worldwide.This study employs panel data from 293 Chinese cities from 2014 to 2022 to systematically analyze the impact of the Zero-Waste City policy on PM_(2.5)concentration using a difference-in-differences model.The findings indicate that the policy not only directly reduces PM_(2.5)concentration but also indirectly curbs PM_(2.5)emissions by enhancing green innovation and green economic efficiency.Moreover,the policy’s effects are found to be positively moderated by urban energy dependence and digital financial inclusion,while they are negatively moderated by the government debt ratio.Based on these findings,this study suggests that cities should actively develop their digital economy,reduce government debt,promote green innovation,and improve green economic efficiency,as doing so will enhance their implementation of environmental policies and promote sustainable urban development.
文摘为帮助企业更好地适应现实业务中的动态环境,研究了运输价格不确定性的多时段多式联运路径与存储协同优化模型。首先,在运输价格确定的环境下建立整数规划数学模型。其次,在运输价格不确定的环境下建立鲁棒优化模型,并将鲁棒优化模型转化为等价的线性鲁棒对等问题。随后,在传统k-短路算法、迭代贪婪(iterative greedy,IG)算法和自适应大邻域搜索算法(adaptive large neighbourhood search,ALNS)的基础上,提出了混合启发式算法MKIGALNS求解。最后,通过不同规模的算例实验,验证了所提出模型的正确性以及算法的有效性。实验结果表示,在10组算例中,不允许存储时的平均总运营成本为439191元,允许存储时的平均总运营成本为391378元,因此应当进行存储决策,有利于运营成本的降低。鲁棒实验结果表明,随着不确定预算取值的变化,总运营成本以及多时段多式联运运营策略发生变化,揭示了其内在联系。
文摘Based on personality trait theory and experiential learning theory,lots of studies have revealed a reverse causal relationship between volunteering and the non-cognitive abilities of college students.Using data from a longitudinal survey of college students in Hunan Province,China,this study employed the difference-in-differences method to examine the causal relationship between volunteering and non-cognitive abilities,aiming to determine whether volunteering screens or cultivates the non-cognitive abilities of college students.The findings confirmed the screening effect of volunteering on extraversion and conscientiousness and the cultivating effect on agreeableness.However,there was neither a screening effect nor a cultivating effect on emotional stability and openness.It is indicated that volunteering during college primarily screens the non-cognitive abilities of students through personality trait mechanisms,with a limited cultivating effect on non-cognitive abilities.This highlights the necessity to prompt a re-evaluation of how volunteering fulfills its educational function.
基金Supported by the National Natural Science Foundation of China(NSFC)(Grant No.72173131)for“Research on New Trends and Driving Forces in China’s Labor Income Share:A Micro Perspective Based on Enterprise Behavior”the China Postdoctoral Science Foundation(Grant No.2023M743940)for“Research on the Income Distribution Effects of Transport Infrastructure Construction:Theoretical Analysis and Quantitative Assessment”.
文摘Amid China’s rapid economic growth,significant regional imbalances persisted.To address this disparity,it is essential to pursue high-quality development by fostering endogenous drivers within poverty-stricken areas.In late 2011,the Chinese government introduced a new nationwide regional poverty alleviation and development program.This study examines the macroeconomic impacts and micro-level mechanisms of these policies by leveraging manually compiled policy documents and macro and micro data(county economies,enterprises,and land transactions),using a DID approach.The findings reveal that the program significantly boosted economic growth in poor regions without causing negative spillovers to neighboring or paired-assistance areas.Economic growth in the assisted regions was primarily driven by industrialization,encompassing both scale expansion and efficiency gains.A cost-benefit analysis further confirms substantial economic returns and long-term fiscal sustainability.These results provide important policy implications for refining regional poverty policies and advancing balanced development.
基金supported by the Special Project for Training Young Science and Technology Talents in Early Career Development of Jiangxi Province,China(Grant No.20244BCE52087).
文摘This study proposes a regression-based estimation method in difference-in-differences settings in the presence of time-varying covariates-a scenario commonly encountered in applications.We impose only a conditional parallel trends assumption with timevarying covariates and plausible assumptions on the conditional expectation functions.We show that a family of causal effect parameters is exactly the coefficient estimators from our proposed regressions even in the presence of staggered treatment timing and treatment effect heterogeneity across cohorts,time periods,and covariates.These parameters can be further aggregated to the dynamic treatment effects and the overall effect of being treated.We establish the corresponding asymptotic properties.Simulation studies suggest that our proposed regression-based estimators successfully outperform in estimating the causal parameters.Finally,we apply this method to evaluate the effect of intrastate bank deregulation on income inequality in the United States in the setting of Beck et al.(2010).We find substantially different results based on our proposed method.
基金Natural Science Foundation of China(Key Program,No 72133003)Key Projects of Philosophy and Social Sciences Research,Ministry of Education,(Grant No.:22JZD008).
文摘The green credit policy(GCP)is an essential financial policy tool for solving the problem of environmental pollution,and urban energy conservation is an effective way to achieve the goal of carbon neutrality.However,existing research has not verified the energy-saving effects of green credit(GC)at the city level.Based on panel data from 283 cities in China,this study aims to investigate whether GC can effectively reduce urban energy intensity(EI),which is an important complement to existing research.In terms of research methods,to better evaluate the effect of the policy and exclude the influence of other relevant factors,this study considers the promulgation of the Green Credit Guideline(GCG)in 2012 as the basic event,uses the difference-in-differences(DID)model to investigate the impact of GC on EI,and discusses the main impact mechanism.The key results are follows.(1)GC can effectively reduce urban EI.(2)Public environmental demand positively regulates the negative correlation between GC and EI.(3)GC reduces EI through three main channels:government support,capital investment,and technological innovation;however,the mechanism of industrial structure has no significant effect.(4)The effect of GC is more significant in areas with large urban scales,low environmental regulation intensity,and high industrial agglomeration.Based on the above results,this study presents puts forward targeted policy recommendations to strengthen the role of GC in urban sustainable development.
文摘Drawing on local legitimacy theory,which posits that firms seek acceptance and approval from their local community and stakeholders,we examine the effect of corporate governance(CG)quality on corporate social responsibility(CSR)activities in Korea.Enhancing CG quality and engaging in CSR activities are increasingly important for firms’long-term sustainability.Using the KEJI-CSR index and the KCGS CG score,we find that CG quality positively influences CSR activities.Specifically,if the CG quality score increases by one standard deviation,CSR improves by approximately 1.6–2.3%of the mean CSR score.Furthermore,the relationship between CG and CSR is stronger for business conglomerates(chaebol-affiliated firms),suggesting that sound CG practices can promote CSR activities more effectively when the interests of management and stakeholders are better aligned.This finding supports local legitimacy theory.Our findings are robust under various tests,including difference-in-differences analysis and propensity score matching.An interesting policy implication is that multinational enterprises or foreign investors should prioritize the CG quality of their local subsidiaries or investee firms.Better CG practices can enhance CSR activities,which are essential for long-term survival in local markets.This study,however,is limited to Korea and may not be generalizable to other emerging markets with different governance structures.
基金supported by the National Institute of Environmental Health Sciences(NIEHS)of United States(No.R00ES027511)the National Natural Science Foundation of China(No.42201303).
文摘Long-term exposure to fine particulate matters(PM_(2.5))has been associated with respiratory and cardiovascular diseases and the burden are potentially higher in China experiencing heavy air pollution.In this study,we established the exposure-response association between long-term exposures to PM_(2.5)and lung function and blood pressure in Chinesemiddle-aged and older adults using linearmixed-effects and generalized additive mixedmodels based on 3 waves longitudinal health outcomes data by enrolling 19,988 participants from 121 cities across themainland of China.We also assessed the effect of Clean Air Policy(CAP)based on a quasi-experimental difference-in-differences(DID)design.A 10μg/m^(3)increase in PM_(2.5)concentration was associated with a 7.18(95%confidence interval[CI]:-8.35,-6.02)L/min decrease in PEF(peak expiratory flow)and a 0.72(95%[CI]:0.53,0.90)and a 0.30(95%[CI]:0.18,0.42)mmHg increase in systolic and diastolic blood pressure,respectively.The associations were more pronounced in males and rural areas for PEF,but similar across subgroups for blood pressure.DID results suggested that the effect of CAP on health outcomes were sensitive tomagnitudes of reduction in PM_(2.5).A 5μg/m^(3)reduction in PM_(2.5)or more generally led to 18.70(95%[CI]:0.79,36.61)higher PEF and-2.05(95%[CI]:-3.87,-0.23)lower diastolic blood pressure,respectively,compared to no reduction or increase in exposure.However,the effects were significant only in rural areas.Our analysis support CAP aiming to benefit public health and provides insights to inform future control policy for efficiently decreasing air pollution exposure burden.
基金supported by The Yangtze River Joint Research Phase Ⅱ Program(No.2022-LHYJ-02-0402).
文摘Environmental protection policies(EPPs)play a pivotal role in advancing sustainable development and maintaining ecological balance by establishing clear directives and standards.However,a comprehensive methodology to evaluate the effectiveness of these policies remains underdeveloped.Here,we employ a difference-in-differences(DID)approach to assess the effectiveness of EPPs,using the implementation of the Resident Work(RW)policy as a quasi-natural experiment.Drawing on urban-level panel data from the Yangtze River Basin between 2016 and 2021,we demonstrate that the DID model robustly evaluates the RW policy's impact on water quality improvement.Cities that adopted the RW policy experienced a 0.0098 reduction in water pollution compared to non-adopting cities.A dynamic analysis revealed progressive water quality improvements over time,with stronger effects observed in economically disadvantaged cities.Furthermore,higher policy evaluation scores correlated with greater improvements in water quality.This study highlights the utility of the DID model in quantifying EPP effectiveness and offers a scalable framework for policy evaluation in environmental management.
