The aim of this study was to document the dietary diversity status of preschool children in poor, rural, and ethnic minority areas of Central South China and examine its associated factors both at home and in preschools. A cross-sectional study including 1328 preschool children aged three or five years from two nationally designated poverty counties in Hunan Province was conducted. A dietary diversity score (DDS) was constructed to measure the dietary patterns based on the 24 h recall method. The mean DDS among the sample children was 5.77 (95% confidence interval: 5.70–5.83, range 1 to 9) with a standard deviation of 1.22. Both household characteristics (including the education level of the child’s primary caregiver and the nutritional knowledge of the caregiver) and preschool factors (including the nutritional knowledge of the child’s preschool principal and teachers, nutritional training to children, and the preschool kitchen manager) were positively associated with children’s DDS. The dietary diversity status of children in poor, rural, and ethnic minority areas of Central South China is much lower than that of their peers in other areas. Nutritional education should be provided to caregivers, preschool staff, and children to narrow the gap.

Both home-grown school feeding (HGSF) and short food supply chain (SFSC) emphasize on proximity and aim to strengthen the competitiveness of local smallholder farmers. From a theoretical perspective, HGSF implemented as a type of SFSC could help deliver synergies. A pivotal question is how HGSF can be combined with SFSC and the benefits and drawbacks of such combination. Using an HGSF program which was implemented as an integral part of a free preschool lunch pilot in South Central China, this paper shows that HGSF and SFSC (in its full term) could be combined through one structured demand intervention. This study uses both qualitative and quantitative materials. Qualitative data were collected through focus group discussions with government and preschool staff, parents or caregivers, cooks, World Food Programme representatives and other stakeholders involved in the pilot program. The quantitative part used both small panel data and cross-sectional data from 106 smallholders. This study analyzes the design, implementation, good practices, benefits and constraints of the HGSF-SFSC model. We find that direct purchase from smallholder farmers was linked with higher income and production and dietary diversity. Moreover, this study identifies several constraints of the current HGSF-SFSC model. The policy implications for sustaining and scaling up the current pilot are discussed in the paper.

Understanding how ecological compensation policies reshape ecosystem service (ES) interactions is critical for sustainable watershed management. Using the Miyun Reservoir Basin in northern China as a case study, we examined the dynamic changes in land use, provision of ES, and their trade-offs and synergies (TOS) from 2010 to 2023. Four ES—food production (FP), water yield (WY), nutrient retention (nitrogen and phosphorus, NR and PR), and soil retention (SR)—were quantified using the InVEST model. Spearman’s rank correlation was employed to assess TOS at 1 km, 3 km, and township-level administrative units, and geographically weighted regression (GWR) was applied to explore spatial heterogeneity of ES TOS. Results show: (1) Land use change reflected ecological restoration efforts, with cropland decreasing by 1.69% and forest expanding by 2.16%. (2) ES exhibited spatial heterogeneity; regulating services (WY, NR, PR, SR) improved substantially after 2018, while the FP centroid shifted from downstream to upstream areas. (3) Before 2018, FP showed strong trade-offs with regulating services; following intensified policy implementation, these relationships transformed into synergies. (4) Scale effects were evident: grid-scale TOS were stable, while township-level interactions weakened due to administrative aggregation. Overall, ecological compensation reduced ES trade-offs and enhanced synergies, supporting ecological protection in key water source areas while highlighting the need for performance-based policy refinement.

While information theory is widely used to quantify knowledge combinations, the fundamental principles guiding reference selection in science remain largely unexplored. This study analyzes a large-scale journal citation network to introduce and empirically validate a principle we term “Mediating Similarity”. We posit that a journal’s reference list acts as a strategic cognitive bridge, creating a more efficient informational path from its specific research identity to the broader scientific landscape. Using information-theoretic measures and computational experiments, we tested this principle and its underlying mechanisms. Our findings provide robust, multi-level evidence. First, we confirm the universality of the principle, showing that the mediated path through references is consistently more efficient than the direct path for thousands of journals. Second, perturbation experiments reveal a dual mechanism guiding reference selection: real-world reference portfolios are not merely collections of relevant works, but are synergistically optimal combinations that vastly outperform randomly assembled alternatives. This global optimization, however, operates as a robust “satisficing” strategy, balancing the search for an ideal cognitive path with the practical constraints of scientific discovery. Collectively, these findings reframe reference behavior as a strategic process of navigating a cognitive energy landscape, where journals selectively curate references to enhance their integrative capacity and innovative potential.

Information theory, originally rooted in thermodynamics, is utilized in scientometrics to quantify the diversity and heterogeneity of knowledge combinations. This study analyzes a large-scale journal citation network to introduce and empirically validate a fundamental principle of reference behavior, which we term "Mediating Similarity." We posit that a journal's reference distribution (the knowledge it cites) acts as a cognitive bridge between its own citation distribution (its identity in the scientific landscape) and the overall scientific content distribution (the broader knowledge environment). This phenomenon is captured by the Kullback-Leibler (KL) divergence inequality: the sum of the distances from a journal to its references and from its references to the global landscape is less than the direct distance from the journal to the global landscape. Our experimental findings provide robust, multi-level evidence for this principle. First, we demonstrate the universality of the phenomenon, showing that for all 19,129 journals in our dataset, the mediated KL divergence path is consistently shorter than the direct path. Second, we conducted two perturbation experiments on the top 500 journals ranked by the SJR indicator. Based on our finding that real references are mostly contained within the closest journals as measured by KL divergence, we created a high-relevance candidate pool for each journal, consisting of its real references plus twice the actual number of citations closest un-cited journals. In a global resampling test, we found that the actual reference portfolio exhibited a lower "cognitive energy" (sum of KL divergences) than 99% of 1,000 randomly assembled portfolios from the candidate pool averagely.This indicates that citation is a holistic process that selects for a synergistically optimal combination of references. In a local perturbation test where 10% of real references were swapped, the actual portfolio still outperformed the majority of 1,000 perturbed variations. This suggests that the real-world reference selection process, while driven by an optimization principle, operates as a robust "satisficing" strategy within the constraints of the scientific discovery process. Collectively, these findings reveal that reference behavior is a strategic process. Journals selectively curate references to construct an optimal cognitive path, efficiently shortening the distance between their field and the broader scientific environment.