Urban Areas In China Research Articles

The Digital Divide: Immobility and Vulnerability of Marginalized Groups in Urban Areas in China

The research report delves into the formation and impact paradigm of the digital divide in urban marginalized areas, with a particular attention of how digital divides affect the daily lives of urban marginalized groups. While existing analysis of digital divide in China have predominantly focus on differences between urban and rural areas or eastern and western area, this study centres its attention on the community of Junyuan, Qiaokou District, Wuhan, Hubei Province. Herein lies an research of how the digital divide generated and its ramifications for urban life within a community primarily inhabited by low-income residents, elderly individuals, and migrant workers. Survey results are compared with international research findings related to the digital divide. This comparison leads to a proposed influence paradigm tailored for urban fringe communities based on age and education level. Furthermore, a governance approach is recommended that places emphasis on cultivating user willingness and fostering trust in ICT technology as part of efforts to alleviate the adverse effects of the DD experienced by marginalized groups within cities.

Exploring ultrafine particle emission characteristics from in-use light-duty diesel trucks in China using a portable measurement system

Diesel vehicle exhaust is one of the major contributors to ultrafine particles (UFPs) in urban areas in China. However, there is still a lack of knowledge about UFPs emission characteristics from current in-use diesel vehicles. This study has carried out an on-road test of 10 in-use Light-duty Diesel Trucks (LDDTs) with different emission control standards in China using a self-established portable measurement system based on the Electronic Low-pressure Impactor (ELPI) and characterized the ultrafine particle number (PN) concentration, particle size distribution and metal element contents. The results revealed a significant reduction of 93.37% in the average PN0.1 emission factor of LDDTs from China IV to China VI. Notably, LDDTs compliant with the China VI vehicle emission control standard exhibited the lowest PN0.1 and PM0.1 emission factors, measuring 4.991×1014 #/km and 0.627 g/km, respectively. By taking into account emissions under real driving conditions, we found that the PN emission rates grow with the increase of the Vehicle Specific Power (VSP). The cold-start phase had higher PN emissions than the hot-start phase, with 8590, 1890, 477, and 22 times higher than those of the ambient air (1.18×105 #/cm3), respectively. The installation of Diesel Particulate Filter (DPF) can decrease UFPs by more than 99.8%, while the PN emission factor during the DPF regeneration stage (1.85×1016 #/km) increased by 5 orders of magnitude that of the DPF normal works (7.51×1011 #/km). Metal element contents analysis shows that Fe, Ca, Al and Mg are the dominant elements in UFPs of LDDT exhaust gas, but the element of Ni is slightly increasing in a China VI, possibly due to the new automotive engine exhaust manifolds being made of Ni instead of cast iron for the purpose of having more high-temperature resistance. Our study demonstrates the importance of monitoring and routine maintenance of exhaust after-treatment systems.

Future pathways for green hydrogen: Analyzing the nexus of renewable energy consumption and hydrogen development in Chinese cities

Hydrogen energy offers a promising pathway for achieving zero-carbon urban energy consumption. This study quantitatively analyzes the patterns of hydrogen energy development and its linked to electricity consumption in China's urban areas. It investigates the spatial relationships between hydrogen energy expansion, the potential for green hydrogen production, and overall energy use. Utilizing a coupling coordination degree (CCD) model and a panel vector autoregressive (PVAR) model, the research explores the dynamic interactions between urban hydrogen energy development and the transition to renewable energy sources. In line with Chinese government policy, the study also conducts a scenario analysis of green hydrogen production by 2030, proposing a consumption strategy that balances environmental sustainability with economic growth. The key conclusions are as follows: (1) There is a spatial mismatch between the locations where hydrogen energy is being developed and where the potential for green hydrogen production is greatest. Cities with higher electricity consumption demonstrate stronger synergies in the coordinated development of hydrogen and renewable energy. (2) The development of hydrogen energy significantly accelerates the transition to renewable energy consumption in urban areas, with this impact being more substantial than that of the utilization capacity alone. (3) Hydrogen production in the Plan Scenario is significantly higher than in the Pessimistic Scenario, underscoring the critical importance of implementing renewable hydrogen projects in provinces with high production potential. Future trends in green hydrogen consumption at the provincial level indicate that addressing the challenges of efficient inter-provincial transportation of hydrogen energy remains essential.

Exploration of the Urbanization Process and Its Impact on Vegetation in 125 Resource-Based Cities in China and Comparison with Other Cities

Resource-based cities (RBCs) in China are at a historic juncture in their transformative development. Observing and assessing the role of the resource curse in urban expansion and greening is crucial for the sustainable development of these cities. This study proposes a new framework to extract urban boundary data from 2000 to 2020 in China. Utilizing these data, we analyzed differences in urban expansion intensity and urban vegetation cover between 125 RBCs and 223 non-RBCs. We found the following: (1) While urban areas in China experienced steady growth from 2000 to 2020, the urban area expansion rates of RBCs lagged behind those non-RBCs located in the same geographical areas except in South China, with the lowest annual expansion rate of 1.18% occurring in the Northeast. (2) Although the existing urban areas in some cities show a greening trend, both existing and new urban areas in China are predominantly characterized overall by browning. Surprisingly, RBCs exhibit a stronger greening trend than non-RBCs, particularly in Northwestern China. (3) There is a nuanced interplay and coexistence between resource dependency and urban expansion, with a specific negative correlation when resource dependency is very high or very low. This study provides a novel method and approach for urban boundary delineation. It offers new insights into the developmental characteristics of RBCs, enriching the theoretical framework of resource curse research and supporting the green development of RBCs with robust data.

Evaluating social sustainability of urban regeneration in historic urban areas in China: The case of Xi'an

Urban regeneration involves a highly contested process of social transformation. Examples from China have shown that this process has led to poor social sustainability. Previous studies have not adequately addressed the issue of poor social sustainability. This study aims to address this gap by developing a set of valid and reliable performance indicators for assessing the social sustainability of urban regeneration initiatives in China's Historic Urban Areas (HUAs). Through an extensive literature review and a Delphi survey, critical social sustainability factors facilitating urban regeneration were identified. An assessment tool was subsequently proposed, comprising eight themes, 29 indicators, and a corresponding point-scoring system. Finally, Xi'an was selected as a case study to apply and test the applicability of the tool and to evaluate social sustainability performance to further explore improvement strategies. The results show that adequate housing, housing quality, participation in regeneration initiatives, and safe design were the most critical indicators determining the social sustainability of urban regeneration. Additionally, the results reveal indicators with limited contribution to achieving social sustainability in Xi'an. The research findings have policy implications for pushing socially sustainable urban regeneration initiatives in China.

Transmission of tuberculosis in rural Henan, China: a prospective population-based genomic spatial epidemiological study

ABSTRACT The incidence of tuberculosis (TB) has declined more slowly in rural than urban areas in China, and data on the patterns of transmission and the high-risk populations in rural areas remains scarce. We conducted a population-based study of culture-positive pulmonary TB patients diagnosed in rural Linzhou City, Henan Province from July 2018 to February 2023. Genomic clusters were defined based on whole-genome sequencing and risk factors for clustering were identified by logistic regression. Transmission events were inferred with phybreak and transmission links were sought through epidemiological investigation of clustered patients. Logistic regression was used to explore the relationship between genomic differences of patient isolates and geographical distances of patient residences. Spatial hotspots were defined using kernel density estimation. Of 455 culture-positive patients, 430 were included in the final analysis. Overall, 192 (44.7%,192/430) patients were grouped into 49 clusters. Clusters containing ≥5 patients accounted for 18.4% (9/49) of the clusters and clustering was highest in student patients. No super-spreaders were detected. Confirmed epidemiologic links were identified for only 18.2% of clustered patients. The clustering risk decreased rapidly with increasing distances between patient residences, but 77.6% of clustered patient pairs lived ≥5.0 km apart. Both the Central Subdistrict and Rencun Township were identified as hotspots for TB transmission. Recent transmission appears to be an important driver of the TB burden in Linzhou. The formulation of effective strategies to reduce TB incidence in rural areas will require further studies to identify high-risk populations and venues where local inhabitants congregate and transmit the infection.

Public participation and NGO activity in nature-based solutions in urban areas of China

This paper analyses the degree and types of public participation in Nature-Based Solutions (NBS) projects in China. The paper is based upon the premise that NBS affect multiple aspects of the city as a place for the daily lives and activities of citizens and that NBS implementation can benefit from citizen and stakeholder involvement. NBS thus offer a platform for stimulating engagement between the local government and the public. Case studies are examined through a literature review, site visits, and interviews with researchers, local officials and NGOs in China. The paper indicates that there has been significant progress since the 1990s in formal requirements of public participation through Chinese legislation promoting the inclusiveness of the public in environmental and NBS decision-making, and acknowledgment of the importance of NGOs, however actual implementation of soliciting public opinion and involvement in NBS project design has been more limited. The case studies suggest that the level of involvement of the public in NBS activities and decision-making is the reciprocal of the size of the project, where there is a high-level of involvement in the smaller local projects, but minimal involvement in larger-scale NBS projects. We find that Public Private Partnerships (PPPs) have a significant potential to help finance NBS projects providing the project can forecast low risk and positive revenue for investors, therefore this model would merit further exploration. However, PPPs may also involve limited public participation by citizens and stakeholders beyond private companies and may therefore require targeted efforts to address local communities’ needs and interests. Local people are the most important (and willing) actors and opinionators in projects that directly affect their lives, livelihoods and well-being. The findings highlight the important role of NGOs in promoting and facilitating public participation, and accompanying co-benefits, in several of the Chinese case studies. Our study also suggests that symbiosis between local governments and the citizens could be invoked by local community-based organisations (e.g. Community Resident Committees or similar) that can act as a liaison point and catalyst to public participation in NBS projects, although significant training would also be required.

The Impact of Environmental Factors on Mental Health and Well-being in Urban Areas of China

Background: Over the years, a lot of work has been done within the context of Chinese industry, promoting industrialized urban areas. As a result, the environment of the associated industrialized urban regions has been polluted mainly due to the promotion of emissions. This might also impact the associated individuals' overall mental health and wellbeing. As a result, the current study has focused on the impact of environmental factors on mental health and wellbeing of the individuals within the context of industrialized urban areas in China. Methods: For this purpose, the "China Labor-force Dynamic Survey (CLDS) dataset" of 2020 was considered. A regression model was used to determine the impact of work environment, subjective perception and built environment on the mental health of the associated citizens. In this regard, the industrial employees were also taken into account. Results: The results obtained from this research show significant association within the context of mental health and industrial employees, however, significant association was observed within the context of residents (p < 0.05). Conclusion: In conclusion the environmental factors essentially play an essential role in influencing the mental wellbeing of the individuals, emphasizing the integration of greener environment to attain significant outcomes.

The Influence of Three-Dimensional Building Morphology on PM2.5 Concentrations in the Yangtze River Delta

The rapid urbanization of urban areas in China has brought about great variation in the layout of cities and serious air pollution. Recently, the focus has been directed toward understanding the role of urban morphology in the generation and spread of atmospheric pollution, particularly in PM2.5 emissions. However, there have been limited investigations into the impact of three-dimensional (3D) features on changes in PM2.5 concentrations. By analyzing a wealth of data on building structures based on a mixed linear model and variance partition analysis in the Yangtze River Delta throughout 2018, this study sought to examine the associations between PM2.5 concentrations and urban building form, and further compared the contributions of two-dimensional (2D) and 3D building features. The findings revealed that both 2D and 3D building forms played an important role in PM2.5 concentrations. Notably, the greater contribution of 3D building forms on PM2.5 concentrations was observed, especially during the summer, where they accounted for 20% compared to 7% for 2D forms. In particular, the building height range emerged as a crucial local factor affecting PM2.5 concentrations, contributing up to 12%. Moreover, taller buildings with more variability in height were found to aid in the dispersion of pollution. These results underscore the substantial contribution of 3D building morphology to PM2.5 pollution, contrasting with previous studies. Furthermore, compact buildings were linked to lower pollution levels, and an urban landscape characterized by polycentric urban structures and lower fragmentation was deemed more favorable for sustainable urban development. This study is significant in investigating the contribution of 3D morphology to PM2.5 and its importance for pollution dispersion mechanisms. It suggests the adoption of a polycentric urban form with a broader range of building heights in urban planning for local governments in the Yangtze River Delta.

The coordinated development among economy, society, energy, and environment and their impacts on public health in China's cities

As China's urban areas rapidly developed, prefecture-level cities faced challenges in the coordinated development of the economy, society, energy, and environment (ESEE), which could impact public health. Previous research had examined the interactions between the various ESEE systems and their effects on public health. However, relatively few studies had conducted comprehensive analyses across different systems and regions. This paper aimed to conduct an in-depth analysis in this field. First, it calculated the ESEE development levels using principal component analysis, the entropy method, and data from 278 Chinese cities between 2012 and 2021. Next, it employed a coupling coordination degree model, which reflects the degree of coordinated development between different systems, to explore the coordinated development levels and trends of the four ESEE systems in each prefecture-level city. Furthermore, this paper innovatively used a spatial Durbin model, incorporating ESEE coordination levels to investigate their impact on public health in local and surrounding areas. The results indicated that the positive impact of ESEE coordinated development on local public health was 0.5082, while the impact on surrounding areas was 2.0240. This influence was more pronounced in smaller cities, suggesting the need to enhance regional cooperation, balance developmental disparities, and promote ESEE coordinated development to improve public health.

Is it a matter of design?

Rural and urban areas in China have traditionally represented contrasting realms, largely due to the country’s dual social structure. However, efforts to reduce inequalities and encourage harmonious planning are reshaping both urban and rural landscapes, leading to new hybridized forms of living. These transformations emphasize the importance of design disciplines in experimenting with innovative settlement models and architectural projects. Recognizing the interconnectedness and mutual dependence of urban and rural areas is a fertile perspective to frame the countryside as a significant frontier in China’s cutting-edge architectural movements. China’s rural revitalization strategy represents the latest initiative aimed at improving conditions in the Chinese countryside and enhancing the well-being of its residents. Aligned with the principles of ecological civilization, this policy calls for the development of new esthetic dimensions that reflect technological advancements, cultural diversity, socioeconomic values, and political narratives, echoing similar sustainable agendas worldwide. The contributions selected for this special issue showcase how various design attitudes have embodied the countryside development mandate in far-sighted proposals of transformation that addresses several crucial challenges of contemporary living, such as wealth distribution, economic stimulation, cultural heritage preservation, and the relationship with nature. These examples suggest that by challenging the ideological commitments supporting their feasibility, design practice, and research can be fundamental tools for reorienting policy formulation beyond solving specific issues through targeted design approaches.

Research on the Development Characteristics of Urban Commercial Districts in the Consumer Society: A Case Study of Shanghai

With the advent of the consumer era, the spatial structure of urban areas in China has undergone significant changes, exhibiting new development characteristics. This study aims to investigate the consumer space structure, functional structure, and consumer demand from three dimensions. By examining the development history, architectural space, and community form, as well as studying the basic attributes and behavioral characteristics of consumers, it summarizes that Shanghai’s commercial communities demonstrate a mutual penetration of consumption and non-consumption. The need for a community-oriented, experiential integration of commercial formats is evident in these areas.

Study on main sources of aerosol pH and new methods for additional reduction of PM2.5 during winter severe pollution: Based on the PMF-GAS model

In recent years, the air quality in urban areas of China has been a significant improvement. However, further advancements in air quality remain challenging, particularly in addressing the persistent problem of severe particulate matter (PM) pollution in winter. In-depth research on the aerosol acidity (pH) is beneficial for analyzing the pollution characteristics of PM and providing support for the continuous improvement of PM pollution. In this study, the sources of water-soluble inorganic ions (WSIIs) of PM2.5 in Zhengzhou were analyzed based on the PMF-GAS method, and the contribution of different sources to aerosol acidity was further investigated in conjunction with the ISORROPIA-II thermodynamic model. The research results indicate that secondary aerosols are the main source, and controlling the emissions of secondary aerosols and gaseous precursors is a crucial measure for reducing PM2.5 concentrations. Furthermore, the study revealed that targeted reductions of major pollution sources across varying pH ranges could significantly lower PM2.5 concentrations. In the range of pH < 4, when the contribution of secondary aerosol source is 23.9%, PM2.5 concentrations can be reduced by 40.6%, resulting in an additional emission reduction of 5.9 μg m−3. In the range of 4 < pH < 6, PM2.5 can be reduced by 36.9% at a contribution of 16.5% from secondary aerosol source, achieving an additional emission reduction of 7.0 μg m−3. This research provides important theoretical support for gaining a deeper understanding of the sources and control of atmospheric pollution, offering strategies to expedite the achievement of PM2.5 standards and further mitigating its impacts on human health and the environment.

Time-series China urban land use mapping (2016–2022): An approach for achieving spatial-consistency and semantic-transition rationality in temporal domain

The global urbanization trend is geographically manifested through city expansion and the renewal of internal urban structures and functions. Time-series urban land use (ULU) maps are vital for capturing dynamic land changes in the urbanization process, giving valuable insights into urban development and its environmental consequences. Recent studies have mapped ULU in some cities with a unified model, but ignored the regional differences among cities; and they generated ULU maps year by year, but ignored temporal correlations between years; thus, they could be weak in large-scale and long time-series ULU monitoring. Accordingly, we introduce an temporal-spatial-semantic collaborative (TSS) mapping framework to generating accurate ULU maps with considering regional differences and temporal correlations. Firstly, to support model training, a large-scale ULU sample dataset based on OpenStreetMap (OSM) and Sentinel-2 imagery is automatically constructed, providing a total number of 56,412 samples with a size of 512 × 512 which are divided into six sub-regions in China and used for training different classification models. Then, an urban land use mapping network (ULUNet) is proposed to recognize ULU. This model utilizes a primary and an auxiliary encoder to process noisy OSM samples and can enhance the model's robustness under noisy labels. Finally, taking the temporal correlations of ULU into consideration, the recognized ULU are optimized, whose boundaries are unified by a time-series co-segmentation, and whose categories are modified by a knowledge-data driven method. To verify the effectiveness of the proposed method, we consider all urban areas in China (254,566 km2), and produce a time-series China urban land use dataset (CULU) at a 10-m resolution, spanning from 2016 to 2022, with an overall accuracy of CULU is 82.42%. Through comparison, it can be found that CULU outperforms existing datasets such as EULUC-China and UFZ-31cities in data accuracies, spatial boundaries consistencies and land use transitions logicality. The results indicate that the proposed method and generated dataset can play important roles in land use change monitoring, ecological-environmental evolution analysis, and also sustainable city development.

Shyness, Sport Engagement, and Internalizing Problems in Chinese Children: The Moderating Role of Class Sport Participation in a Multi-Level Model.

The relations between shyness and internalizing problems have been mainly explored at the individual level, with little known about its dynamics at the group level. This study aims to examine the mediating effect of individual-level sport engagement and the moderating effect of class-level sport participation in the relations between shyness and internalizing problems. The participants were 951 children attending primary and middle school from grade 3 to grade 7 (Mage = 11 years, 509 boys) in urban areas of China. Cross-sectional data were collected using self-report assessments. Multi-level analysis indicated that (1) shyness was positively associated with internalizing problems; (2) sport engagement partially mediated the relations between shyness and internalizing problems; and (3) class sport participation was a cross-level moderator in the mediating relations between shyness, sport engagement, and internalizing problems. Shy children in classes with a higher level of sport participation tend to have less sport engagement and more internalizing problems than those in classes with a lower level of sport participation. These findings illuminate implications from a multi-level perspective for shy children's adjustment in a Chinese context. The well-being of shy children could be improved by intervening in sport activity, addressing both individual engagement and group dynamics, such as class participation.

Kolmogorov-Zurbenko filter coupled with machine learning to reveal multiple drivers of surface ozone pollution in China from 2015 to 2022

Near-surface ozone pollution is a significant concern in China. Its meteorological drivers are uncontrolled, stressing an urgent need to quantify the anthropogenic-driven components. This study employs explainable machine learning (ML) algorithms to predict ozone concentrations, emphasizing the anthropogenic-driven trends after accounting for meteorological effects. Results present that radiation is the most important meteorological factor affecting ozone pollution in the Yangtze River Delta (YRD), Pearl River Delta (PRD), and Sichuan Basin (SCB), while temperature is dominant for the North China Plain (NCP). Even at lower temperatures, stronger solar radiation can still lead to the accumulation of higher ozone concentrations. The anthropogenic-driven ozone concentration showed an upward trend in China, with an interannual growth rate of 2.61 μg/m3 a−1 from 2015 to 2022. Nonetheless, its rising trend experienced a post-2019 downturn, due to the COVID-19 lockdown and emission reduction strategies. It started to rise in 2022. Regionally, NCP has the highest ozone concentration, the SCB has the most pronounced increase in 2022, but the PRD has no noticeable variation and no significant seasonal change after 2019. As for precursor emissions, the urban areas in China are mostly located in the VOC-limited (volatile organic component) and transitional regimes, highlighting that VOC control is more cost-effective.

Giving It a Shot with a Different Approach: Prosocial Strategies Moderate the Joint Effects of Agentic and Communal Goals on Bullying.

This study uses polynomial regression and response surface analyses to investigate the joint effects of agentic and communal goals on bullying and the moderating role of prosocial strategies. The sample included 917 adolescents (Mage = 13.54, SD = 1.02) from rural, suburban, and urban areas in China. The findings revealed that higher agentic and lower communal goals were associated with a linear rise in bullying. Surprisingly, when both social goals were higher simultaneously, bullying followed an inverted U-shaped pattern. Furthermore, prosocial strategies moderated the joint effects of the two social goals. Adolescents who are more likely to use prosocial strategies do not show significant changes in bullying when both goals are at a higher level. In contrast, those who are less likely to do so show a linear rise in bullying, regardless of changes in social goals. This study improves our understanding and intervention of bullying behavior, emphasizing a non-pathological perspective.

Extensive inequality of residential greenspace exposure within urban areas in China

Ensuring residents' equal access to high quality urban greenspace is vital for urban environmental justice and sustainable urban development. However, most previous studies have mainly focused on greenspace quantity, overlooking its quality. Moreover, the national-level spatial distribution pattern of residential greenspace exposure (RGE) within urban areas remains unclear. Here, we have improved the existing RGE assessment framework by integrating both the quality and quantity of urban greenspace to evaluate RGE and its associated inequality across 119,692 blocks in 334 Chinese cities in 2020. We find that the spatial distribution pattern of RGE varies with urban size. Large cities exhibit a distinct clustering of low RGE in their central areas, whereas small cities tend to show a pronounced clustering of high RGE in the central areas. RGE in Chinese cities indicates extensive inequality, as the average RGE of high-exposed people is nearly four times greater than that of low-exposed people. Moreover, residents in larger cities are more prone to experiencing greater inequalities compared to those in smaller cities. We also find that the landscape metrics (i.e., connectance index and mean Euclidean nearest-neighbor distance) of greenspace possess a strong explanatory power (R2 = 0.431) for the observed inequality. Our study underscores the importance of optimizing the landscape structure of urban greenspace and enhancing equality in the quality of greenspace. These findings provide novel insights for urban greenspace planning and promoting urban environmental justice.

Social-emotional problems in 3-to 5-year-old children: a cross-sectional study of highly educated migrants in a Chinese urban area.

Previous research has primarily examined the mental well-being of children from labor migrant families, yet there is a lack of understanding regarding the mental well-being of children from highly educated migrant backgrounds. This study investigated the social-emotional problems of 3-5-year-olds from highly educated migrant families residing in an urban area of China, as well as explored potential differences in demographic variables. A cross-sectional study was conducted in Qiantang District, Hangzhou, China, with 1,494 (53.3% boys) children selected via a convenient sampling method. The Ages & Stages Questionnaires: social-Emotional, Second Edition (ASQ:SE-2) was used to measure social-emotional problems. The results showed that 23.6% of the children were at risk for social-emotional problems. More boys (26.7%) than girls (20.1%) had scores above the cut-off. Additionally, more children in the low socioeconomic status (29.9%) had scores above the cut-off than those in the high socioeconomic status (18.9%). There were three common issues among all age groups: "being more active than others," "excessive attachment to parents," and "being overly friendly with strangers. The social-emotional development of children from highly educated migrant families is a significant aspect that deserves recognition, contributing valuable insights to the existing literature on this topic.

Planning and reconstruction of the old city in the future

With the acceleration of urbanization, the renovation planning and renovation of old urban areas have become an important issue. This article conducts an in-depth analysis of a case study on the renovation and planning of an old urban area in China, exploring how to achieve modernisation and sustainable development of the old urban area while preserving its historical and cultural heritage This article adopts a case study method, selects typical cities as research objects, deeply analyses the practical process, effectiveness, and challenges of urban renovation planning and old house reconstruction, and proposes corresponding strategic suggestions. Through detailed analysis and comparison of the case, the aim is to provide useful reference and guidance for other cities in terms of renovation planning and old house reconstruction.