Quantifying cerebral blood flow changes using arterial spin labeling: A comparative study of idiopathic rapid eye movement sleep behavior disorder and Parkinson's disease.

INTRODUCTION: Idiopathic rapid eye movement sleep behavior disorder (iRBD) and Parkinson's disease (PD) have been found to have changes in cerebral perfusion and overlap of some of the lesioned brain areas. However, a consensus regarding the specific location and diagnostic significance of these cerebral blood perfusion alternations remains elusive in both iRBD and PD. The present study evaluated the patterns of cerebral blood flow changes in iRBD and PD. MATERIAL AND METHODS: A total of 59 right-handed subjects were enrolled, including 15 patients with iRBD, 20 patients with PD, and 24 healthy controls (HC). They were randomly divided into groups at a ratio of 4 to 1 for training and testing. A PASL sequence was employed to obtain quantitative cerebral blood flow (CBF) maps. The CBF values were calculated from these acquired maps. In addition, AutoGluon was employed to construct a classifier for CBF features selection and classification. An independent t-test was performed for CBF variations, with age and sex as nuisance variables. The performance of the feature was evaluated using receiver operating characteristic (ROC) curves. A significance level of P < 0.05 was considered significant. CBF in several brain regions, including the left median cingulate and paracingulate gyri and the right middle occipital gyrus (MOG), showed significant differences between PD and HC, demonstrating good classification performance. The combined model that integrates all features achieved even higher performance with an AUC of 0.9380. Additionally, CBF values in multiple brain regions, including the right MOG and the left angular gyrus, displayed significant differences between PD and iRBD. Particularly, CBF values in the left angular gyrus exhibited good performance in classifying PD and iRBD. The combined model achieved improved performance, with an AUC of 0.8533. No significant differences were found in brain regions when comparing CBF values between iRBD and HC subjects. CONCLUSIONS: ASL-based quantitative CBF change features can offer reliable biomarkers to assist in the diagnosis of PD. Regarding the characteristic of CBF in the right MOG, it is anticipated to serve as an imaging biomarker for predicting the progression of iRBD to PD.

Impact of International Trade on the Carbon Intensity of Human Well-Being.

There has been a longstanding debate about the impact of international trade on the environment and human well-being, yet there is little known about such environment and human well-being trade-off. Here, we explore the effect of international trade on the carbon intensity of human well-being (CIWB) globally under the current global trade system and a hypothetical no-trade scenario. We found that between 1995 and 2015, CIWB of 41% of countries declined and 59% of countries increased, caused by international trade, and this resulted in a reduction of the global CIWB and a decline in CIWB inequality between countries. International trade decreased CIWB for high- and upper-middle-income countries and increased CIWB for lower- and middle-income countries. In addition, our results also show that decreases in emission intensity are the most important driver of lower CIWB and the percentage contribution of emission intensity to the improvement in CIWB increases with income. The reduction of emission intensity, population growth, and increase in life expectancy all contribute to CIWB reduction, while the consumption level is the primary factor driving CIWB growth. Our results underscore the importance of studying the impact of international trade on the CIWB of countries at different stages of development.

Exploring the Coordination and Spatial-Temporal Characteristics of the Tourism-Economy-Environment Development in the Pearl River Delta Urban Agglomeration, China.

The rise of mass tourism has encouraged rapid economic growth; meanwhile, the eco-environmental system has come under increasing pressure. To achieve sustainable development, it is critical to deeply explore the relationship and evolution characteristics between three subsystems: tourism, the economy, and the eco-environment. This study aims to develop a more comprehensive indicator system for evaluating the coupling coordination degree (CCD) of the tourism-economy-environment (TEE) system using statistical data from nine cities in the Pearl River Delta (PRD) urban agglomeration from 2010 to 2019. We investigated the spatial-temporal evolution characteristics and driving forces of the TEE system in the PRD using the CCD model and the geo-detector model. The research results show the following: (1) The comprehensive benefits of the TEE system have increased steadily over the past 10 years, whereas the benefits of the eco-environment subsystem have fluctuated and been relatively unstable. (2) Spatially, in terms of tourism development, the eastern regions of the PRD are more developed than the western regions, and the regions with the greatest tourism benefits have gradually shifted to the northeastern regions of the PRD. Economic development presented an imbalanced but relatively stable spatial pattern. Guangzhou and Shenzhen have been the two most economically developed cities over the past 10 years. The eco-environment development has fluctuated over time, revealing a spatial pattern of cities with low environmental benefits in the center and cities with high eco-environmental benefits in the surrounding regions. (3) The PRD's TEE system has become more integrated, moving from moderate disorder to a model of high-quality coordinated development, demonstrating a spatial pattern in which the cities of high development coordination are located near the Pearl River Estuary, and the coordination decreases the further away they are from the estuary. (4) The major driving factors of heterogeneous TEE coordination development include eco-environment protection, opening-up policies, education investment, technological innovation level, and the regional economic development level. The results are expected to effectively promote economic, tourism, and environmental improvement in the PRD, as well as to provide policy recommendations for coordinated TEE development in other similar urban agglomerations.

Spatial-temporal Evolution and Influencing Factors of Digital Financial Inclusion: County-level Evidence from China.

The vigorous development of information and communications technology has accelerated reshaping of the financial industry. The COVID-19 pandemic has further catalyzed the demand for digital financial services. Digital financial inclusion relies on information technology to overcome spatial limitations. In this case, the research question is whether it adheres to the spatial laws governing conventional financial activities. This study uses exploratory spatial data analysis and a geographical detector to elucidate the spatiotemporal characteristics and factors influencing digital financial inclusion at the county level in China (Data don't include that of Hong Kong, Macao and Taiwan of China) from 2014 to 2020. The research findings indicate: first, China's county-level digital financial inclusion is generally increasing and exhibits significant spatial autocorrelation. Second, population density, level of traditional financial development, government regulation, and education level are key determinants of China's county-level digital financial inclusion. Third, policies should be differentiated by region to narrow the spatial gap in digital financial inclusion. The results provide a reference for other developing countries on using digital technology to develop financial inclusion.

Evolution and control of the COVID-19 pandemic: A global perspective.

We investigated the factors influencing the progression of the pandemic from a global perspective by using the Geodetector and Correlation methods and explored the pandemic response policies and effects in different countries. The results yielded three notable findings. First, empirical results show the COVID-19 pandemic is influenced by various factors, including demographic and economic parameters, international travelers, urbanization ratio, urban population, etc. Among them, the correlation between urban population and confirmed cases is strongest. Cities become the key factor affecting the COVID-19 pandemic, with high urbanization levels and population mobility increases the risk of large-scale outbreaks. Second, among control measures, School-closures, International-travel-restrictions, and Public-gathering-restriction have the best control effect on the epidemic. In addition, the combination of different types of control measures is more effective in controlling the outbreak, especially for Public-gathering-restrictions ∩ School-closures, International-travel-restrictions ∩ Workplace-closures, Public-transport-restrictions ∩ International-travel-restrictions. Third, implementing appropriate control measures in the first month of an outbreak played a critical role in future pandemic trends. Since there are few local cases in this period and the control measures have an obvious effect.

Coupling Coordination Degree between the Socioeconomic and Eco-Environmental Benefits of Koktokay Global Geopark in China.

The rapid economic growth of geoparks has put pressure on their ecological environments. Therefore, to ensure the sustainable development of geoparks, we must explore the coupling relationship between their socioeconomic benefits (SEBs) and eco-environmental benefits (EEBs). Based on coupling coordination theory and using statistical data from 2005 to 2018, in this study, we aimed to establish an indicator system for evaluating the coupling coordination degree (CCD) between the SEBs and EEBs of the Koktokay Global Geopark in China, which is both theoretically and practically relevant for research on the sustainable development of geoparks. As a result, we found the following: First, the comprehensive development level of the SEBs of the Koktokay Global Geopark showed a fluctuating upward trend during the study period. Second, the comprehensive development level of the EEBs of the geopark remained stable but fluctuated slightly: it declined from 2009 to 2012, affected by the deterioration of the eco-environment, and fell to its lowest point in 2012. By strengthening the protection of the eco-environment of geoparks, the EEBs gradually improved and became stable. Finally, we found that the CCD between the SEBs and EEBs of the Koktokay Global Geopark improved from mildly disordered to basically coordinated, indicating that the CCD is developing toward an increasingly higher level. The purpose of this study was to promote the reasonable development of geotourism while focusing on a sound eco-environment and to provide recommendations for the sustainable development of the Koktokay Global Geopark and a reference for the development of other similar geoparks.

The Relationship Between Built Environment and Mental Health of Older Adults: Mediating Effects of Perceptions of Community Cohesion and Community Safety and the Moderating Effect of Income.

Many studies revealed a significant correlation between low-density built environment and the mental health of older adults in developed countries. However, scholars and decision-makers recently began to pay close attention to the effect of this relationship in high-density built environments and in developing countries. Using point-of-interest (POI) data from Baidu and data on 20 communities in Guangzhou, China, which were collected through a questionnaire survey, this study aimed to examine the relationship between built environment and the mental health of older adults as well as the physiological-psychological mediating paths between the two, so as to enrich the research on population aging in the high-density urban context in developing countries. The findings indicated that facility accessibility and distance to parks significantly positively correlated with the mental health of older adults and the number of public transit stations, and the distance to these stations significantly negatively correlated with the mental health of older adults. Also, the perceptions of community cohesion and community safety had a significant mediating effect between the built environment and the mental health of older adults. Furthermore, the moderating effect analysis results verified the moderating effect of income: with an increase in income, the perception of community cohesion enhanced the protection of the mental health of older adults and reduced the mediating effect of the perception of community safety. The results provided a reference for policy-makers and urban planners in their efforts to plan and build health-supporting communities and a healthy aging society.

Fire-Prevention Characteristics of an Active Colloid Prepared from Stimulated Fly Ash Component.

In this paper, an active colloid (AC) with a three-dimensional network framework, prepared from stimulated fly ash (FA) component by an acid-base compound chemical method, was proposed for prevention of coal mine fire. During the stimulation process, the active substance in fly ash can be released and transformed into effective components for fire prevention. Research results show that Al3+, Fe3+, and Ti4+ from FA can serve as metal cross-linking agents to graft-copolymerize with sodium carboxymethyl cellulose. Mg2+ and Ca2+ can be formed into halogenated salts that are encapsulated by composite colloids and cooperate with them to participate in fire prevention. The remaining fly ash solid particles served as an inert component can be fixed in the framework to encapsulate more water, improving the colloid's strength and water retention. The content of the active component was measured by inductively coupled plasma (ICP) emission spectroscopy to evaluate the stimulation effect of fly ash. The gel time, viscosity, water retention, and other performance parameters were determined for evaluation of physical characteristics. The fire-prevention performances of AC were also determined by the inhibition performance test, thermogravimetric analysis, and infrared spectroscopy. Moreover, the fire-prevention mechanism of AC was also explored. These results showed that the AC prepared from the stimulated fly ash component can greatly inhibit the spontaneous combustion of coal and can be chosen as a potential material for prevention of coal mine fire caused by spontaneous combustion of coal.

The Effect of High-Density Built Environments on Elderly Individuals' Physical Health: A Cross-Sectional Study in Guangzhou, China.

The built environment refers to the objective material environment built by humans in cities for living and production activities. Existing studies have proven that the built environment plays a significant role in human health, but little attention is paid to the elderly in this regard. At the same time, existing studies are mainly concentrated in Western developed countries, and there are few empirical studies in developing countries such as China. Based on POI (point of interest) data and 882 questionnaires collected from 20 neighborhoods in Guangzhou, we employ multilevel linear regression modeling, mediating effect modeling, to explore the path and mechanism of the impact of the built environment on elderly individuals' physical health, especially the mediating effects of physical and social interaction activity. The results show that the number of POIs, the distance to the nearest park and square, and the number of parks and squares are significantly positively correlated with the physical health of the elderly, while the number of bus and subway stations and the distance to the nearest station are significantly negatively correlated. Secondly, physical activity and social networks play a separate role in mediating the effect of the built environment on elderly individuals' physical health. The results enrich the research on the built environment and elderly individuals' health in the context of high-density cities in China and provide some reference basis for actively promoting spatial intervention and cultivating a healthy aging society.

Spatiotemporal Difference Characteristics and Influencing Factors of Tourism Urbanization in China's Major Tourist Cities.

Tourism is crucial for promoting industrial development and is an important driver of China's new type of urbanization. A tourism urbanization index system was constructed in three dimensions: the tourism industry, urbanization, and the ecological environment. The spatial-temporal differentiation characteristics and influencing factors of tourism urbanization in 35 major tourist cities in China from 2009 to 2018 were analyzed using the state space method, standard deviation ellipse, and spatial autocorrelation analysis. The results show the following. (1) Over time, the tourism industry index displays an upward trend, the urbanization index exhibits a more obvious upward trend, and the ecological environment index fluctuates strongly. Under the influence of all three factors, the tourism urbanization index shows a fluctuating rising trend. (2) Regarding the spatial distribution pattern, the development center of tourism urbanization shifts to the southeast, and the distribution direction is northeast-southwest. There is a significant agglomeration in global spatial autocorrelation. The local spatial correlation pattern is dominated by correlation characteristics and supplemented by different characteristics. (3) In terms of influencing factors, policy and regional development strategy, tourism resource endowment, economic development level, and traffic conditions are listed in descending order of influencing degree. Finally, we put forward some suggestions.

Urban Food Takeaway Vitality: A New Technique to Assess Urban Vitality.

As one of the most important criteria for measuring the quality of urban life and the environment, urban vitality has become the focus of urban-related research and related disciplines with an increasing number of advocates for the rapid and harmonious development of urban cities. Urban takeaway can represent urban vitality, but studies have not investigated this in a quantitative manner. Furthermore, current studies rarely focus on or even mention the urban food takeaway vitality generated by the spatial distribution of urban takeaway. This study first calculated the vitality of urban takeaways based on the urban takeaway distribution, building footprint, Open Street Map (OSM) data, and the Rapidly Exploring Random Tree (RRT). Then, the urban vitality was obtained using Tencent-Yichuxing data and night-time light data, followed by a spatial correlation analysis between the urban takeaway vitality and urban vitality. Finally, the results for Beijing, Shanghai, and Guangzhou were compared, and the following conclusions were drawn: (1) there is a significant spatial correlation between the urban takeaway vitality and urban vitality, but the correlation varies in different cities at different times; and (2) even in the same city, different road and building densities have an impact on the correlation. The urban takeaway vitality proposed in this study can be used as a new index to evaluate the urban vitality, which has important theoretical and practical significance for the sustainable development of future urban cities.

Spatiotemporal characteristics and determinants of internal migrant population distribution in China from the perspective of urban agglomerations.

Urban agglomerations are fundamental regional units of development and attract large-scale migrant population. Previous studies have only focused on migrant population distribution in major urban agglomerations. Therefore, this study analysed the spatiotemporal characteristics of migrant population distribution in China during 2000-2010 at city level from the perspective of urban agglomerations. The results indicate that urban agglomerations were accumulation areas of migrant population. Numerous people have migrated into 19 urban agglomerations, which has enlarged regional differences in migrant population distribution. The interprovincial migrant population dominated within urban agglomerations, whereas the intraprovincial migrant population dominated outside urban agglomerations. In the future, intraprovincial migration will become the dominant migration mode. The evolution of migrant population distribution pattern in urban agglomerations agrees with classic theories of unbalanced regional development. The determinants of migration in different regions were compared. Results revealed that economic and government driving forces jointly influenced migration; however, economic forces exceeded government forces. Economic forces were more influential within urban agglomerations, whereas government forces played more important roles outside urban agglomerations. Increased income and job opportunities were the core attractions of urban agglomerations. Moreover, with an increase in the urban agglomeration development level, the influence of economic forces increased, whereas that of government forces decreased. The findings provide a deeper understanding of migrant population distribution in China, which will benefit population management across various regions.

Spatial-Temporal Characteristics in Grain Production and Its Influencing Factors in the Huang-Huai-Hai Plain from 1995 to 2018.

The Huang-Huai-Hai Plain is the major crop-producing region in China. Based on the climate and socio-economic data from 1995 to 2018, we analyzed the spatial-temporal characteristics in grain production and its influencing factors by using exploratory spatial data analysis, a gravity center model, a spatial panel data model, and a geographically weighted regression model. The results indicated the following: (1) The grain production of eastern and southern areas was higher, while that of western and northern areas was lower; (2) The grain production center in the Huang-Huai-Hai Plain shifted from the southeast to northwest in Tai'an, and was distributed stably at the border between Jining and Tai'an; (3) The global spatial autocorrelation experienced a changing process of "decline-growth-decline", and the area of hot and cold spots was gradually reduced and stabilized, which indicated that the polarization of grain production in local areas gradually weakened and the spatial difference gradually decreased in the Huang-Huai-Hai Plain; (4) The impact of socio-economic factors has been continuously enhanced while the role of climate factors in grain production has been gradually weakened. The ratio of the effective irrigated area, the amount of fertilizer applied per unit sown area, and the average per capita annual income of rural residents were conducive to the increase in grain production in the Huang-Huai-Hai Plain; however, the effect of the annual precipitation on grain production has become weaker. More importantly, the association between the three factors and grain production was found to be spatially heterogeneous at the local geographic level.

Determinants of Urban Expansion and Spatial Heterogeneity in China.

China is the world's largest developing country and its regions vary considerably. However, spatial heterogeneity in determinants of urban expansion in prefecture-level cities have not been identified. The present study explored the spatiotemporal characteristics of Chinese urban expansion and adopted a geographically weighted regression (GWR) method to determine this spatial heterogeneity. The results indicated that China experienced massive urban expansion during 1990-2015, with urban areas growing from 4.88 × 104 km2 to 1.06 × 105 km2, 46.42% of which was distributed in the eastern region. The results of the GWR model revealed the spatial heterogeneity in the determinants of urban expansion. Marketization was vital for urban expansion and had a stronger impact in the developed eastern and southern regions than in the less-developed northern and western regions. Globalization and decentralization bi-directionally affected urban expansion. The constraining effects of physical factors were limited and stronger in the developing northern region than in the developed southern region. Identifying the varying determinants of urban expansion is essential for policy-making in various regions.

Printable Stretchable Silver Ink and Application to Printed RFID Tags for Wearable Electronics.

A printable elastic silver ink has been developed, which was made of silver flakes, dispersant, and a fluorine rubber and could be sintered at a low temperature. The printed elastic conductors showed low resistivity at 21 µΩ·cm, which is about 13.2 times of bulk silver (1.59 µΩ·cm). Their mechanical properties were investigated by bending, stretching, and cyclic endurance tests. It was found that upon stretching the resistance of printed conductors increased due to deformation and small cracks appeared in the conductor, but was almost reversible when the strain was removed, and the recovery of conductivity was found to be time dependent. Radio-frequency identification (RFID) tags were fabricated by screen printing the stretchable silver ink on a stretchable fabric (lycra). High performance of tag was maintained even with 1000 cycles of stretching. As a practical example of wearable electronics, an RFID tag was printed directly onto a T-shirt, which demonstrated its normal working order in a wearing state.

Does the path of technological progress matter in mitigating China's PM2.5 concentrations? Evidence from three urban agglomerations in China.

Technological progress is widely considered to play an important role in reducing air pollution. While growing literature has explored the effects of technological progress on environmental quality, fewer studies have considered the varied effects exerted by different technological progress paths on PM2.5 concentrations. This paper explored the relationship between two different kinds of technological progress (indigenous innovation and technology diffusion) and PM2.5 concentrations. Indigenous innovation was in this study considered to be composed by research and development investment (R&D) and import technology (IM); technology diffusion was represented by foreign direction investment (FDI) and export learning effect represent (EX). A panel data model was employed in order to explore the varied impact of these different technological progress paths on PM2.5 concentrations, using data for 48 cities located in China's three most developed urban agglomerations (Beijing-Tianjin-Hebei, the Yangtze River Delta, and the Pearl River Delta), for the period 2000-2015. The results reveal that without control variables, FDI had a significant negative impact on PM2.5 levels in Beijing-Tianjin-Hebei, and EX a significant positive impact. FDI, R&D, and EX were found to positively correlate with PM2.5 levels in the Yangtze River Delta. In Pearl River Delta, R&D presented a significant negative relationship. The findings of this study provide decision makers and industry managers with a scientific basis from which to approach the task of mitigating PM2.5 concentrations through technological progress.

Examining the influences of urbanization on carbon dioxide emissions in the Yangtze River Delta, China: Kuznets curve relationship.

Exploring the impacts of urbanization on carbon dioxide emissions is a task that is of great significance in efforts to build low-carbon cities in China. While existing literature has identified links between carbon dioxide emissions and urbanization, the impacts of various mechanisms in various urbanization subsystems (economic, demographic, spatial, and social urbanization) on carbon dioxide emissions remain largely unexplored. This study conducts a comprehensive assessment of the multiple effects of urbanization on carbon dioxide emissions in the Yangtze River Delta, based on city panel remote sensing and statistical data covering the years 1992 to 2013. A stepwise panel data model was applied in combination with environmental Kuznets curve theory, so as to address four aspects of urbanization. The results show that carbon dioxide emissions increased notably in the Yangtze River Delta from 141.01 million tons in 1992 to 1448.28 million tons in 2013, and Shanghai and Suzhou were the largest two emitters in region. The impacts of urbanization on carbon dioxide emissions varied with different subsystems of urbanization. Economic urbanization exerted a positive impact in relation to carbon dioxide emissions with the relation between carbon dioxide emissions and gross domestic product per capita showing a Kuznets curve association. Population urbanization has exerted two opposing effects on carbon dioxide emissions, and population density and the proportion of urban population play a negative and positive role respectively. Spatial urbanization was here positively associated with carbon dioxide emissions, a result of the effects of the construction of new infrastructures and the conversion of existing land uses. Social urbanization demonstrated negative correlations in relation to emissions, mainly by improving low-carbon awareness in the general public. The effects of social consumption were insignificant. In addition, a number of control variables were also estimated to have varied effects on carbon dioxide emissions. The different influences of urbanization must, our findings indicate be considered in the task of formulating emission reduction measures for the Yangtze River Delta. Our analysis casts new light on the importance of exploring the multiple effects of urbanization in relation to emissions, knowledge which is vital to building low-carbon cities.

Does modernization affect carbon dioxide emissions? A panel data analysis.

Modernization refers to the general trend of developmental progress that occurs within human societies. We now know that global warming, a result of carbon dioxide emissions, severely threatens the sustainability of human society. It is therefore of significant theoretical and practical implications that the scientific community more thoroughly investigate the impacts of modernization on CO2 emissions. Surprisingly, only a limited number of studies have addressed this topic previously. As the world's largest developing economy and carbon emitter, China faces the dual challenge of peaking carbon emissions by 2030 while realizing basic modernization by 2035. With the purpose of identifying the implications of China's 2035 modernization goal for its 2030 emission peak goal, this study explored the effects of modernization on carbon dioxide emissions in China. Using a comprehensive indicator system, five modernization indexes-addressing industrialization, agricultural modernization, informatization, urbanization, and ecological modernization-were estimated, along with carbon dioxide emissions, for the period 1997-2016, for 30 Chinese provinces. Panel data modeling was then used to examine the impacts of the five modernization indexes on CO2 emissions in China. The results demonstrate that industrialization, agricultural modernization, informatization, and urbanization exerted positive effects on CO2 emissions during the study period, suggesting these aspects of modernization led to increased carbon dioxide emissions. A negative correlation between ecological modernization and carbon dioxide emission was identified, indicating that ecological modernization helped to abate CO2 emissions. The findings emerging from this study hold significant implications for China's policy makers in promoting decarbonization, suggesting the utility of pursuing new-type industrialization, developing organic agriculture and eco-agriculture, popularizing electronic equipment with low power dissipation, building low-carbon cities, and promoting the ecology-oriented transformation of the modernization model.

What are the impacts of demographic structure on CO2 emissions? A regional analysis in China via heterogeneous panel estimates.

This study comprehensively investigated the impacts of demographic structure on CO2 emissions in China at the national level and the regional level for the first time. Panel cointegration modeling was employed to test the long-run relationships between CO2 emissions and six demographic structure variables, namely, dependency ratio, sex ratio, higher education ratio, industrial employment ratio, urbanization ratio, and average household size. The fully modified ordinary least squares method was then applied to estimate the long-run elasticity of CO2 emissions for the six demographic structure variables. The results suggested that long-run relationships between CO2 emissions and demographic structure existed at both the national level and the regional level. Dependency ratio was found to exert negative effects on CO2 emissions in China and its three sub-regions. Positive associations between sex ratio and CO2 emissions were revealed to exist in China and West China, and CO2 emissions elasticity for sex ratio was relatively high in West China. Higher education ratio had a positive effect on CO2 emissions in East China. Industrial employment ratio was found to positively correlate with CO2 emissions in China, East China, and Central China. Urbanization ratio was demonstrated to increase CO2 emissions at the national level and the regional level, and CO2 emissions elasticity for urbanization ratio decreased from West China to Central China, and then to East China. Negative correlations between average household size and CO2 emissions were detected at both the national level and the regional level. Based on the findings of this study, several practical recommendations were proposed, including optimizing age structure, promoting gender equality, advocating low-carbon lifestyles and low-carbon consumption patterns, promoting industrial upgrading and industrial structure optimization, building low-carbon cities and less carbon-intensive public infrastructure systems, and improving residential energy efficiency.

Examining the Impacts of Urban Form on Air Pollution in Developing Countries: A Case Study of China's Megacities.

Urban form is increasingly being identified as an important determinant of air pollution in developed countries. However, the effect of urban form on air pollution in developing countries has not been adequately addressed in the literature to date, which points to an evident omission in current literature. In order to fill this gap, this study was designed to estimate the impacts of urban form on air pollution for a panel made up of China's five most rapidly developing megacities (Beijing, Tianjin, Shanghai, Chongqing, and Guangzhou) using time series data from 2000 to 2012. Using the official Air Pollution Index (API) data, this study developed three quantitative indicators: mean air pollution index (MAPI), air pollution ratio (APR), and continuous air pollution ratio (CAPR), to evaluate air pollution levels. Moreover, seven landscape metrics were calculated for the assessment of urban form based on three aspects (urban size, urban shape irregularity, and urban fragmentation) using remote sensing data. Panel data models were subsequently employed to quantify the links between urban form and air pollution. The empirical results demonstrate that urban expansion surprisingly helps to reduce air pollution. The substitution of clean energy for dirty energy that results from urbanization in China offers a possible explanation for this finding. Furthermore, urban shape irregularity positively correlated with the number of days with polluted air conditions, a result could be explained in terms of the influence of urban geometry on traffic congestion in Chinese cities. In addition, a negative association was identified between urban fragmentation and the number of continuous days of air pollution, indicating that polycentric urban forms should be adopted in order to shorten continuous pollution processes. If serious about achieving the meaningful alleviation of air pollution, decision makers and urban planners should take urban form into account when developing sustainable cities in developing countries like China.