Hindrance or facilitator? The economic consequences of national demonstration eco-industrial parks in China.

Many countries attach great importance to the green, low-carbon, and circular development of industrial parks. China is one of them and has entered an exploration journey of national demonstration eco-industrial parks (NDEIPs). However, the impact of the transformation of industrial parks into NDEIPs on local economic development still remains a mystery. To address this issue, we develop an empirical study using a combination of the multi-period difference-in-differences method and the propensity score matching method based on the panel data for 266 cities in China from 2001 to 2021. The results show that industrial parks becoming NDEIPs promotes cities' economic development. This conclusion still holds after a series of robustness tests, such as the reverse causality test and the placebo test. Moreover, the park heterogeneity tests show that the economic consequences vary according to differences in levels, industry types, life cycle phases, and the degree of foreign firm agglomeration. The city heterogeneity tests show that the economic consequences differ based on administrative levels, innovation capabilities, technology industrialization, and environmental friendliness. The spatial heterogeneity tests show that the economic consequences differ according to geographical location and whether situated in the Yangtze River Economic Belt. The policy upgrading heterogeneity tests show that the economic consequences differ during the process of policy upgrading and transformation. In addition, the mechanism tests reveal that green innovation, human capital level, and firm attractiveness mediate the relationship between industrial parks becoming NDEIPs and cities' economic development. This study provides a new perspective for understanding the economic effects of the transformation of industrial parks into NDEIPs, and provides a reference for the government on how to maximize these economic effects.

New energy vehicles' technology innovation coordination strategy based on alliance negotiation under dual credit policy.

The development of new energy vehicles (NEVs) is one of the effective ways to alleviate carbon emissions, environmental pollution, and energy scarcity in the transportation sector. The Chinese government has innovatively proposed the "dual credit policy," but it is still a hot topic whether it can promote the NEVs' technological innovation. In this study, we construct game models and obtain the technological innovation strategies for NEVs under the dual credit policy, considering that the NEV supply chain contains one manufacturer and N suppliers. Further, we construct bargaining game models and study how to encourage manufacturers and suppliers to enhance technological innovation, realize supply chain coordination, and give the alliance strategy to maximize suppliers' profit. We found that the dual credit policy can effectively stimulate technological innovation, and the higher the credit price or technological innovation credit factor, the higher the technical level of NEVs. The findings could guide the government to adjust and revise the policy. Second, we found that the bargaining games could coordinate the NEV supply chain so that decentralized enterprises can achieve optimal technological innovation under centralized decision-making. Third, we found that suppliers can improve their profits by choosing a suitable alliance strategy under the manufacturer's different negotiating power.

A prediction index of the volatile organic compounds pollution conditions in a chemical industrial park based on atmospheric stability.

Volatile organic compounds (VOCs), as common precursors of ozone (O3) and fine particulate matter (PM2.5), are a focus of air pollution prevention and control. Furthermore, with the rapid development of industry, industrial sources have become the largest source of anthropogenic VOCs emissions, leading to economic development while causing great harm to the environment. It is becoming meaningful to efficiently predict the future total volatile organic compounds (TVOC) pollution conditions in chemical industrial parks (CIPs), which can assist managers in carrying out corporate emission management in advance. In this study, TVOC monitoring data and meteorological data from January 1, 2022, to December 31, 2022, were used to innovatively construct the TVOC pollution index. This index comprehensively considers the atmospheric stability and localized horizontal diffusion conditions and can quickly and accurately predict the variations in the TVOC in a CIP in the next 7 days. In addition, we used synoptic weather patterns and backward trajectory analysis to explore the mechanism of VOCs pollution formation in a CIP. The results show that the combined influences of a westerly wind pattern, temperatures above 30 °C, a subtropical high pressure system, more upwind pollutants, and the horizontal and vertical diffusion conditions in the CIP were unfavorable, leading to VOCs pollution.

The allocative efficiency of construction land quota in rural China: a perspective of bidders' behavior and regret psychology.

The construction land quota pricing mechanism with cost plus pricing method is not sufficient to reflect its intrinsic value. This diminishes the willingness of farmers to voluntarily reclaim abandoned residential and other rural construction land, leading to suboptimal efficiency in rural land utilization and an excessive squandering of rural land resources. Thus, a sequential auction model with two stages for complementary goods was constructed, which considered the synergic characteristics between the land and quota. Further, regret psychology of bidder was considered in the case of winning or losing. A rational pricing mechanism has been developed to allocate construction land quotas, aiming to enhance farmers' motivation to the vacant homesteads of reclamation and revitalizing the stock of rural construction land. The results revealed that the regret psychology in the case of winning would decrease the transaction price of the quota, i.e., the greater the perceived regret in the case of winning, the more significant the reduction in the bidding price offered. Moreover, the regret psychology in the event of losing/failure would increase the transaction price of quota. Furthermore, publishing only the winner's price after the auction leads to the highest price of the quota offered by the bidder. In contrast, publishing only the loser's bidding price leads to the lowest transaction price of the quota offered by the bidder. In addition, the fee for delayed construction would increase the bidding price of the construction land quota. Therefore, local governments should consider announcing only the winner of price after the quota auction has ended. In addition, imposing a fee for delayed construction would enhance the transaction price of land quota, increase farmers' revenue from land reclamation, and incentivize farmers to reclaim unused rural land.

Enhanced recovery after microdiscectomy: reductions in opioid use, length of stay and cost.

BACKGROUND: Enhanced recovery after surgery (ERAS) protocols are widely used worldwide. Recently, studies of the ERAS program in spinal surgery subspecialties have been reported. The aim of this study was to evaluate the impacts of ERAS in minimally invasive microdiscectomy (MD) surgery. METHODS: This was a retrospective cohort study of patients undergoing MD at a single center. From March 2018 to March 2021, 286 patients were in the ERAS group. A total of 140 patients from March 2017 to February 2018 were in the conventional group. The outcomes included length of stay (LOS), the postoperative numeric rating scale (NRS), complications, 30-day readmission rate, 30-day reoperation rate and cost. Moreover, perioperative factors were also evaluated. RESULTS: Compared with the conventional group, the LOS and cost were reduced in the ERAS group. There were no significant differences in the NRS, complication rate, 30-day readmission or reoperation rates between the groups. Furthermore, postoperative drainage volume, and postoperative opioid use were lower in the ERAS group. CONCLUSIONS: The ERAS protocol for MD surgery reduces LOS, cost and opioid use and accelerates patient recovery.

Construction and application of computerized risk assessment model for supply chain finance under technology empowerment.

This study seeks to assist small and medium enterprises break free of the constraints of the conventional financing model and lessen the supply chain finance risks they face. First, the supply chain financial business model and credit risk are analyzed, followed by a discussion of the application principle of blockchain in the control of supply chain financial credit risk. The next topic up for discussion is the emancipation of individuals and the application of financial technology toward the management of financial risk in supply chains. In the final stage of the development of the computerized risk assessment model, the Fuzzy Support Vector Machine (FSVM) is optimized, and the effectiveness and efficiency of risk classification are enhanced by introducing a variable penalty factor C. To test the efficacy of the C-FSVM risk assessment model, the Chinese auto sector is used as the study's object. According to the results of the study, the C-FSVM model has a classification accuracy of 96.35% for the entire sample, 96.45% for credible firms, and 95.34% for default enterprises. The training time of the C-FSVM model is 473.9s, which is far lower than the SVM and FSVM models' training times of 1631.6s and 1870.2s. In summary, the C-FSVM supply chain financial risk assessment model is effective and has great application value in banking practice.

Epidemiology and the economic burden of traumatic fractures in China: A population-based study.

Objectives: National data on the admission rate, distribution, in-hospital mortality, and economic burden of traumatic fractures in China is unclear. We aimed to conduct a cross-sectional population-based study to determine such above data at the national level in China. Methods: A national administrative database was used to review all traumatic fracture hospitalizations in China during 2020, from which a total of 2,025,169 inpatients with traumatic fractures was retrieved. Admission rates and in-hospital mortality rates stratified by age, sex, and region were calculated. The causes of traumatic fracture and economic burden were described. Results: The admission rate of traumatic fractures of all China population in 2020 was 1.437‰. The admission rate increased with age and varied with genders and causes of injuries. Falls are the leading cause of traumatic fracture hospitalization, followed by road traffic injuries. The most common diagnoses were femoral neck fractures, with a number of 138,377. The in-hospital mortality was 1.209‰. Road traffic injuries led to the highest in-hospital mortality. The median length of stay was 10 days, with the median hospitalization cost of ¥20,900 (about $3,056). Conclusion: Traumatic fractures are concerning conditions with a high admission rate and in-hospital mortality in China, which are mainly caused by falls and road traffic injuries. The government should implement more public health policies to enhance the health of the elderly and improve transportation safety to prevent traumatic fractures.

COVID-19 infection rate but not severity is associated with availability of greenness in the United States.

Human exposure to greenness is associated with COVID-19 prevalence and severity, but most relevant research has focused on the relationships between greenness and COVID-19 infection rates. In contrast, relatively little is known about the associations between greenness and COVID-19 hospitalizations and deaths, which are important for risk assessment, resource allocation, and intervention strategies. Moreover, it is unclear whether greenness could help reduce health inequities by offering more benefits to disadvantaged populations. Here, we estimated the associations between availability of greenness (expressed as population-density-weighted normalized difference vegetation index) and COVID-19 outcomes across the urban-rural continuum gradient in the United States using generalized additive models with a negative binomial distribution. We aggregated individual COVID-19 records at the county level, which includes 3,040 counties for COVID-19 case infection rates, 1,397 counties for case hospitalization rates, and 1,305 counties for case fatality rates. Our area-level ecological study suggests that although availability of greenness shows null relationships with COVID-19 case hospitalization and fatality rates, COVID-19 infection rate is statistically significant and negatively associated with more greenness availability. When performing stratified analyses by different sociodemographic groups, availability of greenness shows stronger negative associations for men than for women, and for adults than for the elderly. This indicates that greenness might have greater health benefits for the former than the latter, and thus has limited effects for ameliorating COVID-19 related inequity. The revealed greenness-COVID-19 links across different space, time and sociodemographic groups provide working hypotheses for the targeted design of nature-based interventions and greening policies to benefit human well-being and reduce health inequity. This has important implications for the post-pandemic recovery and future public health crises.

Factors Influencing Intergovernmental Cooperation on Emission Reduction in Chengdu-Chongqing Urban Agglomeration: An Evolutionary Game Theory Perspective.

In this study, we introduced the realistic problem of a dynamic carbon tax, built several evolutionary game models for cooperative emission reduction by local governments, and determined the factors that influence governments' willingness to cooperate in emission reduction. The findings revealed that, first, the probability of governments opting for cooperative emission reduction strategies increases at different rates depending on the benefits and costs of cooperation. Second, externalities influence governments' willingness to cooperate in emission reduction during cooperative carbon emission reduction. Furthermore, the emergence of a free-riding situation reduces the effectiveness of intergovernmental cooperation in reducing carbon emissions. Third, carbon tax policy can influence the likelihood that local governments will choose cooperative emission reduction, and different carbon tax sizes have different effects on their willingness to choose cooperative emission reduction.

Equality and social determinants of spatial accessibility, availability, and affordability to primary health care in Hong Kong, a descriptive study from the perspective of spatial analysis.

OBJECTIVE: Primary health care (PHC) is widely perceived to be the backbone of health care systems. Since the outbreak of COVID-19, PHC has not only provided primary medical services, but also served as a grassroots network for public health. Our research explored the accessibility, availability, and affordability of primary health care from a spatial perspective, to understand the social determinants affecting access to it in Hong Kong. METHOD: This constitutes a descriptive study from the perspective of spatial analysis. The nearest neighbor method was used to measure the geographic accessibility of PHC based on the road network. The 2SFCA method was used to measure spatial availability and affordability to primary health care, while the SARAR model, Spatial Error model, and Spatial Lag model were then constructed to explain potential factors influencing accessibility and availability of PHC. RESULTS: In terms of accessibility, 95% of residents in Hong Kong can reach a PHC institution within 15 minutes; in terms of availability, 83% of residents can receive PHC service within a month; while in terms of affordability, only 32% of residents can afford PHC services with the support of medical insurance and medical voucher. In Hong Kong, education status and household income show a significant impact on accessibility and availability of PHC. Regions with higher concentrations of residents with post-secondary education receive more PHC resources, while regions with higher concentrations of high-income households show poorer accessibility and poorer availability to PHC. CONCLUSION: The good accessibility and availability of primary health care reflects that the network layout of existing PHC systems in Hong Kong is reasonable and can meet the needs of most residents. No serious gap between social groups further shows equality in resource allocation of PHC in Hong Kong. However, affordability of PHC is not ideal. Indeed, narrowing the gap between availability and affordability is key to fully utilizing the capacity of the PHC system in Hong Kong. The private sector plays an important role in this, but the low coverage of medical insurance in outpatient services exacerbates the crowding of public PHC and underutilization of private PHC. We suggest diverting patients from public to private institutions through medical insurance, medical vouchers, or other ways, to relieve the pressure on the public health system and make full use of existing primary health care in Hong Kong.

Assessment of community vulnerability during the COVID-19 pandemic: Hong Kong as a case study.

The COVID-19 pandemic continues to threaten global public health. Reliable assessment of community vulnerability is therefore essential to fighting and mitigating the pandemic. This study presents a framework that considers the roles of internal and external factors, including the components of social vulnerability, exposure, and sensitivity, to comprehensively and accurately assess community vulnerability to the pandemic. With respect to internal factors, we summarized the inherent social characteristics of people groups using census data and explored the roles of both overall and four major thematic social vulnerabilities in shaping community infection by COVID-19. We then designed two external factors to characterize exposure and sensitivity and implemented an aggregation by multiplying them with the internal social vulnerability to achieve a comprehensive vulnerability assessment. The role of the estimated vulnerability in shaping community infection was evaluated by statistical and spatial analysis as well as by risk factor classification using defined rules. This case study of Hong Kong demonstrated the value of our framework in vulnerability assessment and revealed the role of vulnerability in shaping community infection by COVID-19.

Export trade structure transformation and countermeasures in the context of reverse globalization.

With the development of economic globalization, the problem of unequal distribution of globalization dividends among and within countries has become increasingly serious, and reverse globalization has a great impact on the national economy and export trade. This paper uses the KOF Globalization Index and the world input-output tables in World Input-Output Database (WIOD), and empirically studies the transformation of a country's export trade and export structure in the context of reverse globalization from the perspectives of world, country, industry, subdivided manufacturing and service industry. The results show that reverse globalization has a significant non-linear negative effect on economic development and export trade. Compared with developed and European Union (EU) countries, the exports of developing and non-EU countries are more affected by reverse globalization shocks. Reverse globalization has the greatest inhibition on the secondary industry exports, followed by the tertiary industry. The suppressive effects on the exports of 12 subdivided manufacturing and 14 subdivided service in China are significantly greater than that of the United States, but most of sub-industry exports in the United States are more sensitive. Besides, China's exports of high-product-complexity industry such as metal products, medicinal chemicals, electrical and optical products and mechanical equipments are greatly affected by reverse globalization, while the exports of water transportation, construction, land transportation are relatively less restrained.

Economic Value of Vaccines to Address the COVID-19 Pandemic in Hong Kong: A Cost-Effectiveness Analysis.

Objective The coronavirus disease 2019 (COVID-19) pandemic has imposed significant costs on economies. Safe and effective vaccines are a key tool to control the pandemic; however, vaccination programs can be costly. Are the benefits they bestow worth the costs they incur? The relative value of COVID-19 vaccines has not been widely assessed. In this study, a cost-effectiveness analysis was performed to provide evidence of the economic value of vaccines in Hong Kong. Method We developed a Markov model of COVID-19 infections using a susceptible-infected-recovered structure over a 1-year time horizon from a Hong Kong healthcare sector perspective to measure resource utilization, economic burden, and disease outcomes. The model consisted of two arms: do nothing and implement a vaccination program. We assessed effectiveness using units of quality-adjusted life years (QALYs) to measure the incremental cost-effectiveness at a HKD 1,000,000/QALY threshold. Results The vaccination program, which has reached approximately 72% of the population of Hong Kong with two vaccine doses, was found to have a cost of HKD 22,339,700 per QALY gained from February 2021 to February 2022. At a willingness-to-pay threshold, the vaccination program was not cost-effective in the context of the low prevalence of COVID-19 cases before the Omicron wave. However, the cost-effectiveness of a COVID-19 vaccine is sensitive to the infection rate. Hong Kong is now experiencing the fifth wave of the Omicron. It is estimated that the ICER of the vaccination program from February 2022 to February 2023 was HKD 310,094. The vaccination program in Hong Kong was cost-effective in the context of the Omicron. Conclusions Vaccination programs incur a large economic burden, and we therefore need to acknowledge their limitations in the short term. This will help relevant departments implement vaccination programs. From a longer-term perspective, the vaccination program will show great cost-effectiveness once infection rates are high in a regional outbreak. Compared with other age groups, it is suggested that the elderly population should be prioritized to improve the vaccine coverage rate.

Public Rental Housing and Obesogenic Behaviors among Adults in Hong Kong: Mediator Role of Food and Physical Activity Environment.

Public rental housing (PRH) for low-income families has been shown in several studies to be associated with poor health status and obesity. However, the causes of this health disparity are controversial, and the associations and pathways between PRH and obesogenic behaviors remain unknown. Using cross-sectional survey data of 1977 adults living in Hong Kong (aged or over 18) together with multi-source GIS-based environmental data, we examined the associations between PRH and obesogenic behaviors and the extent to which those associations can be explained by neighborhood food and physical environment. The unhealthy food environment, which relates with infrequent fruit and vegetables consumption, was calculated based on the relative density of fast food restaurants and convenience stores to grocery stores. The physical activity environment, which relates to physical inactivity and prolonged sitting, was assessed in terms of density of sports facilities and street greenery, separately. Regressions and mediation analyses show that PRH was negatively associated with physical inactivity directly and also indirectly via higher sports facilities density; however, PRH was positively associated with unhealthy diet largely directly and positively associated with prolonged sitting indirectly via less street greenery. We advanced the international literature of PRH health impact assessment and its environmental health pathways by providing evidence from the least housing-affordable city in the world. The findings provide planning implications in formulating a healthier PRH community for these low-income PRH households and mitigating health disparities induced by housing type.

Auction mechanism on construction land quota with selection on land location.

Due to unreasonable pricing, farmers have low enthusiasm for reclaiming their homesteads, which can be used to generate construction land quota. This paper studies how to design a feasible pricing mechanism to stimulate the enthusiasm of farmers. First, we analyze the practice that the local government gives the developers with quota the selection, the right to select the location of the land to be auctioned. Then, applying sequential auction theory, we propose first- and second-price sealed-bid sequential auction models and design quota auction pricing mechanisms. Through theoretical and numerical analysis, we obtain the equilibrium strategy and analyze the impact of selection and on developers' bidding pricing on quota. The results show that the selection can enhance the developer's quota bidding price and farmers' income. And the higher the value of selection to the developer, the higher the quota bidding price and farmer's income. Contrarily, the larger the number of developers, the smaller the quota bidding price and farmers' income. Finally, the quota bidding price and farmers' income in the second-price sealed-bid sequential auction are higher than in the first-price sealed-bid sequential auction.

Supply chain coordination strategy for NEVs based on supplier alliance under dual-credit policy.

In this paper, we assume that the supply chain for new energy vehicles (NEVs) consists of a manufacturer and N parts suppliers, considering that the R&D investment of both manufacturer and suppliers will affect the market demand of NEVs and NEVs credit, we construct decentralized and centralized decision-making models under the dual-credit policy to study the R&D investment strategy of supply chain enterprises. Furthermore, considering that suppliers can form alliances, we establish bargaining game models under the conditions of the non-alliance and alliance of suppliers, and discuss the coordination strategy for the NEVs supply chain. It is found that, under the dual-credit policy, the higher the credit coefficient of technology improvement, the higher the transaction price of credits, and the higher the R&D investment of supply chain. Dual-credit policy can effectively encourage NEVs supply chain to increase R&D investment, improve NEV technology level, and improve the profit of supply chain. Under the dual-credit policy, the increment profit distribution strategy based on a bargaining game model can coordinate the NEVs supply chain. When suppliers separately negotiate with the manufacturer, bringing the negotiation sequence forward, the supplier can get more profits. However, as the manufacturer has the right to determine the negotiation sequence, the supplier can only get the profit of the last round of negotiation, and the manufacturer can get excess profit. Forming a suppliers alliance can solve this problem effectively, and increase the profit of all suppliers when the alliance`s negotiating power is improved to a certain threshold.

Assessment of the emission factors for potentially toxic elements from coal-fired boilers and sintering furnaces in a steel production plant.

The emission factor (EF), the weight of potentially toxic elements (PTEs) per unit energy or weight of sinter produced were evaluated for coal-fired boilers and sintering furnaces integrated in a steel plant. From three coal-fired boilers, 15 samples were taken while 22 samples were taken from four sintering furnaces. Investigations were performed on the EF of lead, cadmium, mercury, arsenic and chromium (VI). The coefficient of variance for the first 3 samples from each PTE was used to decide whether 2 more samples were necessary for the investigation. Three samples were sufficient for Cr (VI), however, 5 samples were required for Pb, Cd, Hg, and As, since the variances in concentrations of the first three samples exceeded 20%. The ranges for the ratio of the laboratory-based EF to the default EF applied by the Environment Protection Administration (EPA Taiwan) for Pb, Cd, Hg, and As for the coal-fired boiler were 0.08-0.013, 0.014-0.017, 0.019-0.033, 0.047-0.066 and for the sintering furnaces were 0.059-0.232, 0.05-0.151, 0.05-0.364, and 0.067-0.824. The ratio for Cr (VI)- was constant at 0.005 for all the coal fired boilers while it ranged from 0.057-0.709 for the sintering furnaces. Whilst source identification, enrichment factors, and spatial distributions for PTEs are often studied, laboratory-based investigations on the EFs for PTEs from industrial plants are rarely performed. This study filled the information gap and compared the obtained EFs with the EPA default values. To avoid overcharging industrial plants equipped with the best available technology for emission control, the EPA should apply field investigations and laboratory-based EFs instead of the default EPA EFs to calculate air pollution fees. Insights from this investigation can be applied to promote the adoption of appropriate air pollution control devices to cut down the emission of PTEs.

Spatiotemporal mapping and assessment of daily ground NO2 concentrations in China using high-resolution TROPOMI retrievals.

Nitrogen dioxide (NO2) is an important air pollutant that causes direct harms to the environment and human health. Ground NO2 mapping with high spatiotemporal resolution is critical for fine-scale air pollution and environmental health research. We thus developed a spatiotemporal regression kriging model to map daily high-resolution (3-km) ground NO2 concentrations in China using the Tropospheric Monitoring Instrument (TROPOMI) satellite retrievals and geographical covariates. This model combined geographically and temporally weighted regression with spatiotemporal kriging and achieved robust prediction performance with sample-based and site-based cross-validation R2 values of 0.84 and 0.79. The annual mean and standard deviation of ground NO2 concentrations from June 1, 2018 to May 31, 2019 were predicted to be 15.05 ± 7.82 µg/m3, with that in 0.6% of China's area (10% of the population) exceeding the annual air quality standard (40 µg/m3). The ground NO2 concentrations during the coronavirus disease (COVID-19) period (January and February in 2020) was 14% lower than that during the same period in 2019 and the mean population exposure to ground NO2 was reduced by 25%. This study was the first to use TROPOMI retrievals to map fine-scale daily ground NO2 concentrations across all of China. This was also an early application to use the satellite-estimated ground NO2 data to quantify the impact of the COVID-19 pandemic on the air pollution and population exposures. These newly satellite-derived ground NO2 data with high spatiotemporal resolution have value in advancing environmental and health research in China.

An improved sequential auction with complementarity for pricing the construction land quota.

The paradox between idle homesteads in rural areas and the shortage of construction land in urban areas is concerning. Hence, local governments encourage farmers to reclaim their idle homesteads and farmlands to generate quota. However, the current quota price, which is based on the land reclamation cost, is often inadequate to motivate farmers. This study proposed that the construction land quota and construction land are complementary items, and hence, their pricing should be studied simultaneously instead of independently. Therefore, the classical sequential auction model with complementarity was improved using the core characteristics of quota transactions and those were applied to design optimal pricing mechanisms. Subsequently, the influence of relevant factors on the bidding price was analysed. The results indicated that the bidding price decreases with an increase in the number of bidders and that a bidder's revenue is at a loss when they acquire the quota but fail to obtain the land; hence, the revenue probability is lost. However, bidding prices increase when the fine of delaying construction increases. To raise the quota price and encourage relatively more farmers to reclaim their idle homesteads, local governments should appropriately increase the delaying construction fines or repurchase the quota at a premium from the bidder who acquires the quota but fails to obtain the land, which is beneficial for easing conflict between construction land demands and farmland protection and for promoting the sustainable development of China's social economy.

Impact of product subsidies on R&D investment for new energy vehicle firms: Considering quality preference of the early adopter group.

Different consumer groups accept new energy vehicles sequentially from the perspective of innovation diffusion theory, and the early adopter group has recently been identified. By assuming that the density of early adopters is increasing at minimum acceptable quality thresholds, this paper proposes a vertical quality differentiation model of product R&D with product subsidies. The impact of product subsidies on the R&D investment of new energy vehicle firms is discussed. We show that the early adopters' characteristics may affect the stagnant marginal R&D investment of new energy vehicle firms by increasing sales, which determines the impact mechanism of product subsidies. For firms with decreasing marginal R&D investments, insufficient R&D investments result from financial constraints. If insufficient R&D resources deter firms from conducting R&D, substantial unit subsidies invariably incentivize firms to spend their entire R&D budget. Firms with increasing marginal R&D investments, insufficient R&D profits, or financial constraints are prevented from increasing R&D investment. Product subsidies generally have a crowding-in effect on firms not subject to financial constraints, and this effect increases with the unit subsidy. However, the existence of a crowding-in effect may require sufficiently large unit subsidies. In both situations, product subsidies cannot modulate financial constraints if the firm has spent its entire R&D budget. In the first situation, we also show that product subsidies should be replaced by a funding support policy. In contrast, the second situation shows that a funding support policy should be coordinated with product subsidies.