Xiuqing Li

How administrative-division adjustments influence agricultural production constitutes a vital issue to unpack the linkage between county-level urbanization and food security across China. This paper treats China's new round of county-to-city upgrading (CCU policy) as a quasi-natural experiment and uses county-level panel data from 2000 to 2022 to examine its effect on total grain production through a staggered difference-in-differences approach. The results show that CCU policy significantly increases county-level total grain output. This finding indicates that administrative upgrading does not simply crowd out agricultural production; instead, it may promote grain production through administrative empowerment. Mechanism analysis shows that CCU policy works mainly through three channels: improving agricultural production conditions, optimizing county-level factor allocation, and promoting the transformation of agricultural operations. Further analysis shows that the production-enhancing effect of CCU policy is accompanied by an increase in fertilizer input in the long run, suggesting that grain output growth may exhibit input-intensification characteristics and generate pressure on green agricultural production. Heterogeneity analysis indicates that the positive effect of CCU policy on total grain output is more pronounced in counties with higher terrain ruggedness, in non-major grain-producing areas, and in counties with stronger economic foundations. From the perspective of administrative empowerment, this study extends the literature on the agricultural consequences of county-level urbanization and provides empirical evidence for coordinating administrative division adjustment, grain production capacity, and green agricultural transformation.

Energy poverty is one of the major challenges to global sustainable development, while digital development, as a significant trend of the current era, is considered a key pathway to transcend traditional energy governance frameworks. Anchored in provincial panel data spanning 30 regions across China from 2003 to 2023, this study systematically examines the impact and heterogeneity of digital development on energy poverty and further explores the underlying mechanisms and nonlinear characteristics. The findings show that digital development can significantly alleviate energy poverty, and this conclusion remains valid after addressing endogeneity issues and conducting a series of robustness tests. However, the poverty reduction effect of digital development exhibits significant regional heterogeneity: the mitigation effect in central and western regions is significantly stronger than that in eastern regions, the effect in northern regions is higher than that in southern regions, and the effect in energy-disadvantaged regions is better than that in advantageous regions. Additionally, digital development alleviates energy poverty through mediating pathways such as promoting non-agricultural employment, improving human capital levels, and driving technological innovation. Notably, digital development demonstrates threshold effects and quantile heterogeneity in relation to energy poverty, characterized by diminishing marginal returns as digital development progresses; regions with higher levels of energy poverty experience more significant poverty reduction effects from digital development. This research provides a theoretical basis for energy poverty governance under the global energy crisis and offers empirical references for other countries to achieve energy sustainability goals (SDG7) through context-specific digital transformations.

Research into the resilience of the water-energy-food-ecology (WEFE) system is of great significance to ensure the safety and high quality of resources in the Yellow River Basin. To investigate WEFE system resilience and its influencing factors, this paper constructs an indicator system for WEFE system resilience based on prefecture-level city data from the Yellow River Basin spanning the years 2008 to 2021, and explores its dynamic evolution. Furthermore, this paper employs the Partial Least Squares (PLS) regression model to explore the factors influencing WEFE system resilience. It utilizes a spatial panel model to investigate the spatial spillover effects of these factors. The results indicate that WEFE system resilience in the Yellow River Basin exhibits a fluctuating upward trend. Spatially, a pattern of “low in the middle and upstream regions, high in the downstream regions” emerges. Among the driving factors, infrastructure development and the degree of innovation exhibit negative spatial spillover effects, while other factors demonstrate positive spatial spillover effects. Therefore, integrated basin management needs to be promoted by considering the systematic interlinkages of water, energy, food production and ecology and the sustainable use of resources to ensure the long-term resilience of cities. These findings provide valuable insights for policymakers to formulate more effective and coordinated resource management strategies in the Yellow River Basin, and also contributes to enriching the international literature on WEFE system research.

In this paper, we provide an effective method for estimating the thresholds of the stochastic models with time delays by using of the nonnegative semimartingale convergence theorem. Firstly, we establish the stochastic delay differential equation models for two diseases, and obtain two thresholds of two diseases and the sufficient conditions for the persistence and extinction of two diseases. Then, numerical simulations for co-infection of HIV/AIDS and Gonorrhea in Yunnan Province, China, are carried out. Finally, we discuss some biological implications and focus on the impact of some key model parameters. One of the most interesting findings is that the stochastic fluctuation and time delays introduced into the deterministic models can suppress the outbreak of the diseases, which can provide some useful control strategies to regulate the dynamics of the diseases, and the numerical simulations verify this phenomenon.