OBJECTIVE: To assess the influence of supply and demand factors on the contract behavior of occupational populations with general practitioner (GP) teams.
METHODS: We employed a system dynamics approach to assess and predict the effect of the general practitioner service package (GPSP) and complementary incentive policies on the contract rate for 2015-2030. First, the GPSP is designed to address the unique needs of occupational populations, enhancing the attractiveness of GP contracting services, including three personalized service contents tailored to demand-side considerations: work-related disease prevention (WDP), health education & counseling (HEC), and health-care service (HCS). Second, the complementary incentive policies on the supply-side included income incentives (II), job title promotion (JTP), and education & training (ET). Considering the team collaboration, the income distribution ratio (IDR) was also incorporated into supply-side factors.
RESULTS: The contract rate is predicted to increase to 57.8% by 2030 after the GPSP intervention, representing a 15.4% increase on the non-intervention scenario. WDP and HEC have a slightly higher (by 2%) impact on the contract rate than that from HCS. Regarding the supply-side policies, II have a more significant impact on the contract rate than JTP and ET by 3-5%. The maximum predicted contract rate of 75.2% is expected by 2030 when the IDR is 0.5, i.e., the GP receives 50% of the contract income and other members share 50%.
CONCLUSIONS: The GP service package favorably increased the contract rate among occupational population, particularly after integrating the incentive policies. Specifically, for a given demand level, the targeted content of the package enhanced the attractiveness of contract services. On the supply side, the incentive policies boost GPs\' motivation, and the income distribution motivated other team members.

The security of natural gas supply is not only an important part of China\'s energy security, it also serves as a basic guarantee for China to achieve its dual carbon target and energy transition. Therefore, it is very important to conduct research on the security of China\'s natural gas supply and demand in the context of the dual carbon target. This paper develops a system dynamics (SD) model for natural gas demand forecasting and a generalized Weng\'s model for production forecasting to predict China\'s natural gas demand and production under different scenarios during 2022-2060, and then analyzes China\'s natural gas supply and demand situation and potential import and external dependence based on the forecast results. The simulation results show that (1) under the two demand scenarios D1 and D2, China\'s natural gas demand will peak at 766.02 billion m3 in 2046 and 708.07 billion m3 in 2036 and decline to 521.65 billion m3 and 278.99 billion m3 in 2060 respectively; (2) under the two production scenarios S1 and S2, China\'s natural gas production will peak at 344.581 billion m3 in 2042 and 366.341 billion m3 in 2043 and decrease to about 250 billion m3 in 2060; (3) before 2035, the security of natural gas supply in China will face a challenging situation, the total volume of potential gas imports will gradually increase to about 350 billion m3, and China\'s dependence on natural gas imports will exceed 50%; after 2035, the progress of China\'s energy transition will improve the security of its natural gas supply. This paper proposes four recommendations for expanding gas demand in the near to medium term, promoting conventional and unconventional gas production, diversifying import channels and building emergency reserves to ensure China\'s gas supply security and enable gas to play a \"bridging\" role in the energy transition.

Investigating habitat quality under different climate scenarios holds significant importance for sustainable land resource management and ecological conservation. In this study, considering Nanchang as a case study, a coupled patch-generating land use simulation (PLUS) and system dynamics (SD) model was employed in the simulation and prediction of land usage under shared socioeconomic pathway (SSP) and representative concentration pathway (RCP) scenarios. To assess the habitat quality in Nanchang from 2000 to 2020 and in 2030 under three diverse climate scenarios, we used the Integrated Valuation of Ecosystem Services and Trade-offs (InVEST) model to analyze spatial and temporal changes. The findings indicate that the regions of forest land, cultivated land, and grassland in Nanchang City will dramatically decrease by 2030, the construction land will rapidly expand, and the fluctuations in the unutilized land and water area will be minimal. Additionally, the habitat quality declined from 2000 to 2020, and its spatial distributions changed. Zones having a high overall habitat quality were distributed in the mountains, hills, and lake areas, whereas those with relatively low quality were found in cultivated and urban areas. Under three climate scenarios, in 2030, the habitat quality index for Nanchang City will show a decreasing trend, mainly owing to areas with an index of 0.3-0.5 transitioning to <0.3. Considering each scenario, the degree of habitat degradation increased in the order SSP585>SSP245>SSP119. The findings of this study will inform high-quality development and biodiversity conservation in Nanchang City.

Investigating the CO2 abatement potential of urban residential building from systematic perspective is essential to reach the urban carbon neutrality target. However, previous studies on building CO2 emission trend forecasting were mainly focused on the building operational phase. In this study, a new framework that includes four building stages under a system dynamic model is developed to simulate urban residential building carbon emission changes and the related reduction potentials under three scenarios in Jiangxi Province up to 2060. Results showed that the overall process carbon emission dynamic had already peaked in 2014 under the three scenarios, with a peak value of 38.52 Mt. It then fell to 9.56 Mt in 2060 under the baseline (BAU) scenario. More importantly, seven carbon abatement measures were adopted during four building activities in this study, and the total carbon reduction was not the sum of the carbon reduction potential of the individual measures. Some carbon abatement strategies displayed synergistic effects such as low-carbon electrification where the combination of electrification and clean energy power generation was the largest contributor to reduced carbon emissions during building operation as a comprehensive carbon reduction measure. By contrast, extending a building\'s lifetime restrained the carbon abatement potential during the demolition stage, and it inhibited the carbon emission reduction by 24.84 Mt. These results highlight the significant need for effective policy interventions for clean production and the need to improve prefabricated building proportions, promote electrification, improve energy efficiency, strengthen recycling practices, and extend building lifetimes to promote decarbonization of urban residential building system development.

To compare the long-term effects of the Ministry of Public Health\'s (MOPH) caries preventive interventions for 6- to 12-year-olds (supervised toothbrushing [STB], dental sealant, and combined STB+sealant) to the base case (no intervention) using the System Dynamics Model.
The System Dynamics Model was used to evaluate the intervention scenarios of supervised toothbrushing (STB), sealant, and combined STB+sealant with the base-case scenario. The effectiveness data for the model\'s interventions were obtained from systematic reviews and meta-analyses.
The model determined that the caries-free population increased by 36.2%, 25.5%, and 14.5%, while the caries-affected population decreased by 8.1%, 5.5%, and 3.1% in the combined STB+sealant, sealant, and supervised toothbrushing scenarios compared to the base case at 15 years of age.
Combined STB+sealant is the most efficacious intervention among those administered to children between the ages of 6 and 12 with permanent teeth. In addition, the System Dynamics Model could be helpful in comparing interventions or policies to determine the optimal intervention for a given population.

Understanding the interactions between human and environmental systems is key to sustainable environmental management. Dynamically Coupled Socioeconomic system dynamics models integrated with physically-based Environmental Models (DCSEMs) are promising tools to appropriately capture the non-linear relationships between complex socioeconomic and biophysical systems, thereby supporting sustainable environmental management. However, existing approaches for testing integrated models are commonly based on the point-to-point analysis of model outputs, which is not suitable for DCSEMs that are behaviour pattern oriented. Consequently, the lack of well-defined behaviour pattern-based approaches has limited the adaptability of DCSEMs. To address this gap, this study proposes a novel behaviour pattern-based model testing approach that includes global sensitivity analysis (GSA), auto-calibration algorithms, and evaluation to assess behaviour pattern similarities between model outputs and real-world trends. The proposed approach is demonstrated through a real-world case study, in which an existing DCSEM is calibrated and evaluated to simulate water table depth in the Rechna Doab region of Pakistan. Compared to the conventional numerical point approach, the proposed approach is better suited for DCSEMs, as it replicates observed system behaviour patterns (as opposed to observed point values) over time. Furthermore, the outcomes of the Theil inequality statistical analysis and parameter distribution analysis provide evidence that the suggested approach is effective in testing and improving the performance of the DCSEM by capturing the spatial heterogeneity within the study area. The proposed behaviour-pattern testing procedure is a useful approach for model testing in data-limited, spatially-distributed DCSEMs.

OBJECTIVE: We investigate the obesity transition at the country- and regional-levels, by age, gender, and socioeconomic status (SES) and its relationship to three health behavior attributes, including physical activity (PA), sedentary activities (ST), and consumption of ultra-processed foods (CUPF) within the urban population of Colombia, from 20,010 to 2050.
METHODS: The study is informed by cross-sectional data from ENSIN survey. We used these data to develop a system dynamics model that simulates the dynamics of obesity by body mass index (BMI) categories, gender, and SES. This model also uses a conservative co-flow structure for three health-related behaviors (PA, ST, and CUPF).
RESULTS: At the national level, our results indicate that the burden of obesity is shifting towards populations with lower SES as the gross domestic product (GDP) increases, particularly women aged 20-59 years with lower SES. Among this group of women, the highest burden of obesity is among those who do not meet the PA, ST and CUPF recommendations. At the regional level, our findings suggest that the regions are at different stages in the obesity transition.
CONCLUSIONS: The burden of obesity is shifting towards women with lower SES as GDP increases at the national level and across several regions. This obesity transition is paralleled by a high prevalence of women from low SES groups who do not meet the minimum recommendations for PA, CUPF, and ST. Our findings can be used by decision-makers to inform age- and SES- specific policies seeking to tackle the obesity.

The advancement of electricity market reform highlights the need for China\'s photovoltaic (PV) industry to enter the stage of market competition. Under the carbon neutrality, what impacts electricity market reform has on China\'s PV industry is an important issue that needs to be considered. This paper analyzes the driving mechanism of the marketed on-grid price and constructs a system framework for the internal connection within the PV industry under the background of carbon neutrality. Then, two system dynamics (SD) models are built to perform the numerical simulation and analyze the evolution process. The results indicate that during the market competition stage, (i) the on-grid price will be stable at about 0.07 yuan/kWh by 2060; (ii) China\'s PV industry will go through three stages in the future: the first stage is the \"rush to install\" period for carbon peaking before 2030, followed by the \"sluggish installation\" period from 2030 to 2038. The third stage is the outbreak period of \"PV + multi-scenarios.\"; (iii) under three scenarios by 2060, the proportion of PV power generation will account for 46%, 39%, and 32%, respectively, which are higher than those under the benchmark on-grid price; (iv) it is necessary for the government and enterprises to continue increasing support for research and development (R&D). Finally, we put forward corresponding policy recommendations.

As the issue of global climate change caused by carbon emissions is of great concern, China has proposed achieving its achieve carbon peak goal by 2030. Building carbon emissions account for approximately 50% of China\'s total carbon emissions. It is crucial to study the time and values of building carbon peaks. In this paper, based on a system dynamics model, logarithmic mean Divisia index model and Monte Carlo simulation, we predict the building carbon peak in China. The following conclusions are obtained: 1) in the baseline scenario, China\'s building carbon emissions will peak at 5,427 million tons in 2027. In the high-speed development scenario, China\'s building carbon emissions will peak at 6,298 million tons in 2032. In the coordinated development scenario, the green development scenario, the low-carbon development scenario, and the low-speed development scenario, the peak occurs in 2030 at 5,972 million tons, 5,991 million tons, 5,657 million tons, and 6,329 million tons, respectively. 2) According to the comprehensive simulation, China\'s building carbon emissions will reach the peak in 2030, with an 80% probability of reaching 5,729-6,171 million tons.

OBJECTIVE: To compare the effect of three caries preventive interventions provided by Thailand\'s Ministry of Public Health (MOPH): supervised toothbrushing (STB), fluoride varnish (FV), and combined STB+FV from 0 to 5 years old to the base case using the System Dynamics Model (SDM).
METHODS: The SDM was developed to compare the intervention scenarios: STB, FV, and combined STB+FV with the base case scenario. Meta-analyses determined the effective rates of the interventions included in the model.
RESULTS: The model indicated that the population with no caries in deciduous teeth increased by 7.5%, 5.7%, and 4.2% at three years of age, and 12.8%, 9.9%, and 5.9% at five years of age, under STB+FV, STB, and FV respectively when compared to the base case. At three years old, the population with untreated caries in deciduous teeth decreased by 12.9% in STB+FV, 9.8% in STB, and 7.3% in FV, and by 10.9% in STB+FV, 8.5% in STB, and 4.9% in FV, at five years old. The increase in the population without caries is considered clinically significant compared to baseline.
CONCLUSIONS: The model determined that an effective combination of STB and FV should be administered between 0 and 5 years of age to reduce caries in the primary dentition. The SDM could be applied as a \"what-if\" analysis in order to determine the most beneficial intervention or policy by comparing them.