Exploring the effect of city size on carbon emissions: Evidence from 259 prefecture-level cities in China.

As a gathering place for human production activities, cities are the main places where energy consumption and carbon dioxide emissions occur. How to accurately measure city size and test the impact mechanism of city size on carbon emissions of different city levels is still controversial. This study uses the global nighttime light data to identify urban bright areas and built-up areas, and accordingly constructs the city size index of 259 prefecture level cities in China from 2003 to 2019. It avoids the problem of only considering the single index of population size or space size, and makes the measurement of city size more reasonable. We use a dynamic panel model to study the impact of city size on urban carbon emissions per capita, and discuss the heterogeneity of various cities under different population levels and economic development levels. The empirical results indicate that in the scale of cities in China showed a fluctuating growth trend in recent years. The city size index of most cities is clustered at medium and high values. The city size index of cities with different economic development levels and different population-scale levels shows obvious gradient differences but maintains an upward trend. The expansion of supercities (with a population of more than 5 million) introduces a drastic increase in carbon emissions. The carbon emissions growth caused by the expansion of cities that are classified as third tier and below is the smallest, while that caused by the expansion of cities that are classified as first-tier is the largest. The findings suggest differentiated emissions reduction suggestions for cities with different sizes.

The role of intermediate products in the changes of China's energy use: index decomposition of the MRIO model.

From the perspective of supply chain, energy consumption is an aggregation of energy intensity, intermediate input ratio, and final demand. However, research on the role of intermediate input on energy consumption is rare. This paper disaggregates the complete demand model of China based on MRIO (multi-region input-output model) into final demands and intermediate demands, and applied a decomposition approach combining LMDI (logarithmic mean Divisia index) and SDA (structural decomposition analysis) to evaluate the contribution of intermediate intensity, integrating the respective advantages of SDA and LMDI. The results show that both domestic and international intermediated intensities promote China's energy consumption growth in most years. The reasons are as follows: (1) the intermediate efficiency enhanced; (2) the final consumption structure shifted toward the more complex pattern; (3) the market demanded more energy-intensive final goods. All effects are positive except the energy intensity effect. Based on the consistency in aggregation of LMDI, we found that the aggregation of international effects is bigger than the aggregation of domestic effects, illustrating that international factors are the main driving force of China's energy consumption. The research implies that the intermediate process deserves more attention for the mitigation of energy consumption and greenhouse gas emissions. Improvement of intermediate efficiency and structure will be effective.

Anti-fibrotic, anti-VEGF or radiotherapy treatments as adjuvants for pterygium excision: a systematic review and network meta-analysis.

BACKGROUND: Anti-fibrotic, anti-VEGF (vascular endothelial growth factor) medications, or radiotherapy, as adjuvant for pterygium surgical procedure, has been suggested for reducing recurrence, but difficulties may be experienced in deciding which treatment to use. The purpose of this study was to compare the efficacies of these different adjuvants for preventing recurrence following pterygium surgery. METHODS: We conducted a systematic review to identify randomized controlled trials of patients with primary or recurrent pterygium who received anti-fibrotic, anti-VEGF medication, or radiotherapy as adjuvants in combination with surgical procedure. The surgical procedure contained bare sclera technique or petrygium excision combination with tissue grafting. The primary outcome of this study was recurrence. Direct-comparison and Bayesian network meta-analyses were performed to assess direct and indirect evidence of efficacy. RESULTS: We obtained data from 34 randomized controlled trials, representing a total of 2483 patients. Adjuvants included bevacizumab, 5-FU (5-fluorouracil), MMC (mitomycin C), and ß-RT (beta-radiotherapy). Compared with placebo, we found distinguishable improvement in recurrence with bevacizumab (odds ratio [OR] 0.38, 95% confidence interval [CI] 0.18-0.80), MMC (0.12, 95% CI 0.06-0.21), and ß-RT (0.17, 95% CI 0.04-0.69), but not with 5-FU (0.41, 95% CI 0.12-1.39). MMC significantly reduced recurrence when compared to bevacizumab (0.31, 95% CI 0.13-0.77) and 5-FU (0.28, 95% CI 0.08-0.99). The probability of having the most recurrences after excision was lowest for MMC, followed by bevacizumab and ß-RT. Similar results were found in subgroup analyses, including for primary pterygium, and the patients receiving bare sclera technique or conjunctival autograft. CONCLUSIONS: Adjuvants such as MMC, bevacizumab, and ß-RT could effectively prevent recurrence following pterygium excision. However, their efficacy and acceptability require further clarification in future randomized controlled trials.