38 results on '"Hu, Zengyun"'
Search Results
2. Future challenges of terrestrial water storage over the arid regions of Central Asia
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Peng, Yuzhuo, Zhang, Hao, Zhang, Zhuo, Tang, Bin, Shen, Dongdong, Yin, Gang, Li, Yaoming, Chen, Xi, Hu, Zengyun, and Habib Nazrollozoda, Sulaimon
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- 2024
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3. How does vegetation change under the warm–wet tendency across Xinjiang, China?
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Zhang, Hao, Hu, Zengyun, Zhang, Zhuo, Li, Yaoming, Song, Shiran, and Chen, Xi
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- 2024
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4. Indicator-based assessments of the coupling coordination degree and correlations of water-energy-food-ecology nexus in Uzbekistan
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Song, Shiran, Chen, Xi, Liu, Tie, Zan, Chanjuan, Hu, Zengyun, Huang, Shuangyan, De Maeyer, Philippe, Wang, Min, and Sun, Yu
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- 2023
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5. Deciphering the impact of wind erosion on ecosystem services: An integrated framework for assessment and spatiotemporal analysis in arid regions
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Song, Shiran, Chen, Xi, Hu, Zengyun, Zan, Chanjuan, Liu, Tie, De Maeyer, Philippe, and Sun, Yu
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- 2023
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6. A Unified System for Evaluating, Ranking and Clustering in Diverse Scientific Domains.
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Hu, Zengyun, Chen, Xi, Chen, Deliang, Zhang, Zhuo, Zhou, Qiming, and Li, Qingxiang
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EUCLIDEAN distance , *GEOGRAPHY - Abstract
Evaluating, ranking, and clustering (ERC) stand as fundamental tasks in scientific research, each requiring a mathematical foundation. This study presents an ERC system anchored in the CCHZ-DISO (Chen, Chen, Hu, and Zhou-Distance between Indices of Simulation and Observation) system. Previous research underscores the optimality achieved by the CCHZ-DISO system (Hu et al., 2022). Since the inception of CCHZ- DISO-series research by Hu et al. (2019), DISO has found extensive applications across various domains including geography, hydrology, and economics. Analogous to the CCHZ-DISO system's construction, the ERC system employs the Euclidean distance to perform evaluating, ranking, and clustering tasks. Furthermore, illustrative examples are provided to elucidate the application of the ERC system. In fact, the ERC system unified the evaluating, ranking, and clustering tasks in one simple equation which is more flexible and simpler than the present system. It will have a more widely application than CCHZ-DISO in diverse scientific domains. [ABSTRACT FROM AUTHOR]
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- 2024
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7. Dynamic variations of the COVID-19 disease at different quarantine strategies in Wuhan and mainland China
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Cui, Qianqian, Hu, Zengyun, Li, Yingke, Han, Junmei, Teng, Zhidong, and Qian, Jing
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- 2020
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8. Evaluation and prediction of the COVID-19 variations at different input population and quarantine strategies, a case study in Guangdong province, China
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Hu, Zengyun, Cui, Qianqian, Han, Junmei, Wang, Xia, Sha, Wei E.I., and Teng, Zhidong
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- 2020
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9. Dynamic Changes of Terrestrial Water Cycle Components over Central Asia in the Last Two Decades from 2003 to 2020.
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Odinaev, Mirshakar, Hu, Zengyun, Chen, Xi, Mao, Min, Zhang, Zhuo, Zhang, Hao, and Wang, Meijun
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HYDROLOGIC cycle , *WATER management , *RESOURCE exploitation , *WATER withdrawals , *ARID regions - Abstract
The terrestrial water cycle is important for the arid regions of central Asia (CA). In this study, the spatiotemporal variations in the three climate variables [temperature (TMP), precipitation (PRE), and potential evapotranspiration (PET)] and terrestrial water cycle components [soil moisture (SM), snow water equivalent (SWE), runoff, terrestrial water storage (TWS), and groundwater storage (GWS)] of CA are comprehensively analyzed based on multiple datasets from 2003 to 2020. The major results are as follows: (1) Significant decreasing trends were observed for the TWS anomaly (TWSA) and GWS anomaly (GWSA) during 2003–2020, indicating serious water resource depletion. The annual linear trend values of TWSA and GWSA are −0.31 and −0.27 mm/a, respectively. The depletion centers are distributed over most areas of western and southern Kazakhstan (KAZ) and nearly all areas of Uzbekistan (UZB), Kyrgyzstan (KGZ), and Tajikistan (TJK). (2) TMP and PET have the largest significant negative impacts on SM and SWE. The PRE has a positive impact on terrestrial water variations. (3) During 1999–2019, water withdrawal did not significantly increase, whereas TWS showed a significant decreasing trend. Our results provide a comprehensive analysis of the basic TWS variation that plays a significant role in the water resource management of CA. [ABSTRACT FROM AUTHOR]
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- 2023
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10. Bifurcation analysis of a discrete S I R S epidemic model with standard incidence rate
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Hu, Zengyun, Chang, Linlin, Teng, Zhidong, and Chen, Xi
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- 2016
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11. Climate changes in temperature and precipitation extremes in an alpine grassland of Central Asia
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Hu, Zengyun, Li, Qingxiang, Chen, Xi, Teng, Zhidong, Chen, Changchun, Yin, Gang, and Zhang, Yuqing
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- 2016
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12. Temperature Changes in Central Asia from 1979 to 2011 Based on Multiple Datasets
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Hu, Zengyun, Zhang, Chi, Hu, Qi, and Tian, Hanqin
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- 2014
13. Advanced Climate Simulation and Observation.
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Hu, Zengyun, Tang, Xuguang, and Xin, Qinchuan
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RURAL-urban migration , *ATMOSPHERIC physics , *DROUGHTS , *RADAR meteorology , *GENERATIVE adversarial networks , *METEOROLOGICAL research , *EXTREME weather - Abstract
Global climate changes, particularly extreme weather events, can directly or indirectly affect freshwater availability and food production, and cause disease outbreaks, floods and droughts. Using the advanced research version of the weather research and forecasting model (ARWv3) and a hydrostatic wind speed change equation, Liu et al. [[5]] assessed the effects of four CPSs on a 10 m wind speed simulation over mainland China in the summer of 2003. It was found that the IAP climate model creditably reproduced the spatial patterns of the first three dominant modes of summer rainfall in Thailand, and that the correlation between the observed rainfall anomalies and the Niño 3.4 index could be reproduced through the use of the IAP model. Advanced climate simulations and observations can improve the accuracy of climate change predictions and long-term trends, which can mitigate the impacts of climate events on social and economic development, as well as human lives. [Extracted from the article]
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- 2023
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14. A comparative study of three models to analyze the impact of air pollutants on the number of pulmonary tuberculosis cases in Urumqi, Xinjiang.
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Wang, Yingdan, Gao, Chunjie, Zhao, Tiantian, Jiao, Haiyan, Liao, Ying, Hu, Zengyun, and Wang, Lei
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TUBERCULOSIS ,AIR pollutants ,ENVIRONMENTAL protection ,COMPARATIVE studies ,ENVIRONMENTAL policy ,BOX-Jenkins forecasting - Abstract
In this paper, we separately constructed ARIMA, ARIMAX, and RNN models to determine whether there exists an impact of the air pollutants (such as PM
2.5 , PM10 , CO, O3 , NO2 , and SO2 ) on the number of pulmonary tuberculosis cases from January 2014 to December 2018 in Urumqi, Xinjiang. In addition, by using a new comprehensive evaluation index DISO to compare the performance of three models, it was demonstrated that ARIMAX (1,1,2) × (0,1,1)12 + PM2.5 (lag = 12) model was the optimal one, which was applied to predict the number of pulmonary tuberculosis cases in Urumqi from January 2019 to December 2019. The predicting results were in good agreement with the actual pulmonary tuberculosis cases and shown that pulmonary tuberculosis cases obviously declined, which indicated that the policies of environmental protection and universal health checkups in Urumqi have been very effective in recent years. [ABSTRACT FROM AUTHOR]- Published
- 2023
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15. CCHZ‐DISO: A Timely New Assessment System for Data Quality or Model Performance From Da Dao Zhi Jian.
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Hu, Zengyun, Chen, Deliang, Chen, Xi, Zhou, Qiming, Peng, Yuzhou, Li, Jianfeng, and Sang, Yanfang
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DATA quality , *DATA modeling , *BIG data , *EUCLIDEAN distance , *PHILOSOPHERS - Abstract
With the rapid development of big data, assessment of data quality or model performance has become a hot scientific question. However, most existing lots of metrics focus on specific aspects of the assessment, and comprehensive assessment is rare. Therefore, it is very necessary to develop new assessment system. To address this problem, a new assessment system is constructed which is named after Chen, Chen, Hu, and Zhou (CCHZ)‐distance between indices of simulation and observation (DISO) according to the contributions of Xi Chen, Deliang Chen, Zengyun Hu, and Qiming Zhou. CCHZ‐DISO system builds on the Euclidean Distance and flexible determination of statistical metrics and their numbers. Due to its simplicity and flexibility, CCHZ‐DISO can be readily and widely applied to any subject of science. Therefore, it follows the principle of the Chinese philosopher Lao Zi's Da Dao Zhi Jian which means that the most basic truth is very simple. Plain Language Summary: With the rapid development of big data, assessment of data quality or model performance has become a hot scientific question and plays an essential and key role in any science subject. However, most existing lots of metrics focus on specific aspects of the assessment, and integrative and comprehensive assessment is rare. Therefore, it is very necessary and high urgency to develop new assessment system. To address this problem, in this study, a new assessment system is constructed which is named after Chen, Chen, Hu, and Zhou (CCHZ)‐distance between indices of simulation and observation (DISO) according to the contributions of Xi Chen, Deliang Chen, Zengyun Hu, and Qiming Zhou. CCHZ‐DISO system builds on the Euclidean Distance and flexible determination of statistical metrics and their numbers. Two examples are provided to illustrate the CCHZ‐DISO application. Moreover, we have a brief comparison between CCHZ‐DISO and other approaches to prove the advantage of our new system. Due to its simplicity and flexibility, CCHZ‐DISO can be readily and widely applied to any subject of science. Therefore, it follows the principle of the Chinese philosopher Lao Zi's Da Dao Zhi Jian which means that the most basic truth is very simple. Key Points: A Timely New Assessment System for data quality or model performance is establishedChen, Chen, Hu, and Zhou (CCHZ)‐distance between indices of simulation and observation (DISO) has the advantage to evaluate the overall performance of different models for multiple variables and add the weights of metricsCCHZ‐DISO can be widely used to quality the model performance in any subjects [ABSTRACT FROM AUTHOR]
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- 2022
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16. Indirect Assessment of Watershed SDG7 Development Process Using Nighttime Light Data—An Example of the Aral Sea Watershed.
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Chen, Chaoliang, Sun, Jiayu, Qian, Jing, Chen, Xi, Hu, Zengyun, Jia, Gongxu, Xing, Xiuwei, and Wei, Shujie
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WATERSHED management ,ORDER statistics ,BODIES of water ,SUSTAINABLE development ,WATERSHEDS ,MACHINE learning - Abstract
The accurate calculation of sustainable development indicators is essential for the accurate assessment of the Sustainable Development Goals. This study develops a methodology that combines nighttime light indices, population distribution data, and statistics in order to examine changes and key drivers of SDG7 in the Aral Sea Basin from 2000–2020. In this study, the best-performing combination of four light indices and five simulation methods (two linear regression methods and three machine learning methods) was selected to simulate the spatial distribution of GDP in the Aral Sea Basin. The results showed that: (1) The prediction using the XGBoost model with TNL had better performance than other models. (2) From 2000 to 2020, the GDP of the Aral Sea Basin shows an uneven development pattern while growing rapidly (+101.73 billion, +585.5%), with the GDP of the lower Aral Sea and the Amu Darya River gradually concentrating in the middle Aral Sea and Syr Darya River basins, respectively. At the same time, the GDP of the Aral Sea Basin shows a strong negative correlation with the area of water bodies. (3) Although there is a small increase in the score (+6.57) and ranking (+9) of SDG7 for the Aral Sea Basin from 2000 to 2020, it is difficult to achieve SDG7 in 2030. Deepening inter-basin energy cooperation, enhancing investment in renewable energy, and increasing energy intensity is key to achieving SDG7. [ABSTRACT FROM AUTHOR]
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- 2022
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17. Effect of Vaccination Time Intervals on SARS-COV-2 Omicron Variant Strain Infection in Guangzhou: A Real-World Matched Case–Control Study.
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Li, Yufen, Guo, Tong, Zhong, Jiayi, Fang, Chuanjun, Xiong, Husheng, Hu, Zengyun, Zhu, Yajuan, Tan, Jinlin, Liu, Shuang, Jing, Qinlong, and Zhang, Dingmei
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SARS-CoV-2 Omicron variant ,VACCINATION ,CASE-control method ,VACCINE effectiveness ,COVID-19 pandemic - Abstract
In April 2022, a COVID-19 outbreak caused by the Omicron variant emerged in Guangzhou. A case–control study was conducted to explore the relationship between vaccination intervals and SARS-CoV-2 infection in the real world. According to the vaccination dose and age information of the cases, a 1:4 matched case–control sample was established, finally including n = 242 for the case group and n = 968 for the control group. The results indicated that among the participants who received three vaccine doses, those with an interval of more than 300 days between the receipt of the first vaccine dose and infection (or the first contact with a confirmed case) were less likely to be infected with SARS-CoV-2 than those with an interval of less than 300 days (OR = 0.67, 95% CI = 0.46–0.99). After age-stratified analysis, among participants aged 18–40 years who received two doses of vaccine, those who received the second dose more than 30 days after the first dose were less likely to be infected with SARS-CoV-2 (OR = 0.53, 95% CI = 0.30–0.96). Our findings suggest that we need to extend the interval between the first dose and the second dose and further explore the optimal interval between the first and second and between the second and third doses in order to improve vaccine efficacy. [ABSTRACT FROM AUTHOR]
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- 2022
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18. Complex dynamical behaviors in a discrete eco-epidemiological model with disease in prey
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Hu, Zengyun, Teng, Zhidong, Jia, Chaojun, Zhang, Long, and Chen, Xi
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- 2014
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19. Dynamical analysis and chaos control of a discrete SIS epidemic model
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Hu, Zengyun, Teng, Zhidong, Jia, Chaojun, Zhang, Chi, and Zhang, Long
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- 2014
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20. Spatial Heterogeneity and Its Influencing Factors of Syphilis in Ningxia, Northwest China, from 2004 to 2017: A Spatial Analysis.
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Wang, Ruonan, Li, Xiaolong, Hu, Zengyun, Jing, Wenjun, and Zhao, Yu
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- 2022
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21. Transmission Risk Prediction and Evaluation of Mountain-Type Zoonotic Visceral Leishmaniasis in China Based on Climatic and Environmental Variables.
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Hao, Yuwan, Luo, Zhuowei, Zhao, Jian, Gong, Yanfeng, Li, Yuanyuan, Zhu, Zelin, Tian, Tian, Wang, Qiang, Zhang, Yi, Zhou, Zhengbin, Hu, Zengyun, and Li, Shizhu
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LEISHMANIASIS ,ECOLOGICAL models ,ECOLOGICAL niche ,RISK assessment ,VISCERAL leishmaniasis ,ZOONOSES ,SOCIOECONOMIC factors ,RANDOM forest algorithms - Abstract
With global warming and socioeconomic developments, there is a tendency toward the emergence and spread of mountain-type zoonotic visceral leishmaniasis (MT-ZVL) in China. Timely identification of the transmission risk and spread of MT-ZVL is, therefore, of great significance for effectively interrupting the spread of MT-ZVL and eliminating the disease. In this study, 26 environmental variables—namely, climatic, geographical, and 2 socioeconomic indicators were collected from regions where MT-ZVL patients were detected during the period from 2019 to 2021, to create 10 ecological niche models. The performance of these ecological niche models was evaluated using the area under the receiver-operating characteristic curve (AUC) and true skill statistic (TSS), and ensemble models were created to predict the transmission risk of MT-ZVL in China. All ten ecological niche models were effective at predicting the transmission risk of MT-ZVL in China, and there were significant differences in the mean AUC (H = 33.311, p < 0.05) and TSS values among these ten models (H = 26.344, p < 0.05). The random forest, maximum entropy, generalized boosted, and multivariate adaptive regression splines showed high performance at predicting the transmission risk of MT-ZVL (AUC > 0.95, TSS > 0.85). Ensemble models predicted a transmission risk of MT-ZVL in the provinces of Shanxi, Shaanxi, Henan, Gansu, Sichuan, and Hebei, which was centered in Shanxi Province and presented high spatial clustering characteristics. Multiple ensemble ecological niche models created based on climatic and environmental variables are effective at predicting the transmission risk of MT-ZVL in China. This risk is centered in Shanxi Province and tends towards gradual radiation dispersion to surrounding regions. Our results provide insights into MT-ZVL surveillance in regions at high risk of MT-ZVL. [ABSTRACT FROM AUTHOR]
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- 2022
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22. Modeling and Preliminary Analysis of the Impact of Meteorological Conditions on the COVID-19 Epidemic.
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Sun, Chenglong, Chao, Liya, Li, Haiyan, Hu, Zengyun, Zheng, Hehui, and Li, Qingxiang
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- 2022
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23. Analysis of stability for a discrete ratio-dependent predator-prey system
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Chen, Guangye, Teng, Zhidong, and Hu, Zengyun
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- 2011
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24. Study on the Associations between Meteorological Factors and the Incidence of Pulmonary Tuberculosis in Xinjiang, China.
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Gao, Chunjie, Wang, Yingdan, Hu, Zengyun, Jiao, Haiyan, and Wang, Lei
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WIND speed ,ATMOSPHERIC temperature ,TUBERCULOSIS ,HUMIDITY ,MOVING average process ,LOW temperatures - Abstract
Pulmonary tuberculosis (PTB) has been a major threat to global public health. The association between meteorological factors and the incidence of PTB has been widely investigated by the generalized additive model, auto-regressive integrated moving average model and the distributed lag model, etc. However, these models could not address a non-linear or lag correlation between them. In this paper, a penalized distributed lag non-linear model, as a generalized and improved one, was applied to explore the influence of meteorological factors (such as air temperature, relative humidity and wind speed) on the PTB incidence in Xinjiang from 2004 to 2019. Moreover, we firstly use a comprehensive index (apparent temperature, AT) to access the impact of multiple meteorological factors on the incidence of PTB. It was found that the relationships between air temperature, relative humidity, wind speed, AT and PTB incidence were nonlinear (showed "wave-type ", "invested U-type", "U-type" and "wave-type", respectively). When air temperature at the lowest value (−16.1 °C) could increase the risk of PTB incidence with the highest relative risk (RR = 1.63, 95% CI: 1.21–2.20). An assessment of relative humidity demonstrated an increased risk of PTB incidence between 44.5% and 71.8% with the largest relative risk (RR = 1.49, 95% CI: 1.32–1.67) occurring at 59.2%. Both high and low wind speeds increased the risk of PTB incidence, especially at the lowest wind speed 1.4 m/s (RR = 2.20, 95% CI: 1.95–2.51). In particular, the lag effects of low and high AT on PTB incidence were nonlinear. The lag effects of extreme cold AT (−18.5 °C, 1st percentile) on PTB incidence reached a relative risk peak (RR = 2.18, 95% CI: 2.06–2.31) at lag 1 month. Overall, it was indicated that the environment with low air temperature, suitable relative humidity and wind speed is more conducive to the transmission of PTB, and low AT is associated significantly with increased risk of PTB in Xinjiang. [ABSTRACT FROM AUTHOR]
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- 2022
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25. Spatial-temporal changes to GRACE-derived terrestrial water storage in response to climate change in arid Northwest China.
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Zhou, Qiming, Huang, Junyi, Hu, Zengyun, and Yin, Gang
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CLIMATE change ,SNOWMELT ,METEOROLOGICAL observations ,REGIONAL disparities ,ALPINE glaciers ,HYDROLOGIC cycle ,WATER storage - Abstract
Terrestrial water storage (TWS) is an essential element of the water cycle and a key state variable for land surface–atmosphere interaction. This study investigates the changes of TWS in Xinjiang of China in response to climate change, using Gravity Recovery and Climate Experiment (GRACE)-derived data and ground hydrological/meteorological observations in 2003–2015. The results show that the TWS has an overall significant decreasing trend of −2.8 mm per year. TWS is in a state of surplus in the first half year (from February to July), while it is in a state of deficit in the second half year (from August to next January). The change rates in TWS exhibit strong regional disparities, with profound decreasing trends in Tianshan Mountains and increasing in Kunlun Mountains. Further analyses suggest that the spatial-temporal change of TWS was closely related to the variations in seasonal snow melt and glacier retreat due to temperature and precipitation changes. [ABSTRACT FROM AUTHOR]
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- 2022
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26. Dynamical Variations of the Global COVID‐19 Pandemic Based on a SEICR Disease Model: A New Approach of Yi Hua Jie Mu.
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Wang, Xia, Yin, Gang, Hu, Zengyun, He, Daihai, Cui, Qianqian, Feng, Xiaomei, Teng, Zhidong, Hu, Qi, Li, Jiansen, and Zhou, Qiming
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COVID-19 ,COVID-19 pandemic ,CLIMATE change ,ARID regions ,TEMPERATE climate ,TROPICAL climate - Abstract
The ongoing coronavirus disease 2019 (COVID‐19) pandemic has caused more than 150 million cases of infection to date and poses a serious threat to global public health. In this study, global COVID‐19 data were used to examine the dynamical variations from the perspectives of immunity and contact of 84 countries across the five climate regions: tropical, arid, temperate, and cold. A new approach named Yi Hua Jie Mu is proposed to obtain the transmission rates based on the COVID‐19 data between the countries with the same climate region over the Northern Hemisphere and Southern Hemisphere. Our results suggest that the COVID‐19 pandemic will persist over a long period of time or enter into regular circulation in multiple periods of 1–2 years. Moreover, based on the simulated results by the COVID‐19 data, it is found that the temperate and cold climate regions have higher infection rates than the tropical and arid climate regions, which indicates that climate may modulate the transmission of COVID‐19. The role of the climate on the COVID‐19 variations should be concluded with more data and more cautions. The non‐pharmaceutical interventions still play the key role in controlling and prevention this global pandemic. Plain Language Summary: In this work, global COVID‐19 data were used to examine the dynamical variations from the perspectives of immunity and contact over five climate regions: tropical, arid, temperate, cold, and polar. A new approach is proposed to obtain the infection rates based on the COVID‐19 data between the countries with the same climate region over the Northern Hemisphere and Southern Hemisphere. Our results suggest that the COVID‐19 pandemic will persist over a long period of time or enter into regular circulation in multiple periods of 1–2 years. Moreover, it is found that the temperate and cold climate regions have higher infection rates than the tropical and arid climate regions, which indicates that climate may modulate the transmission of COVID‐19. Key Points: A new approached is proposed to predict the future COVID‐19 variations rather than relying on information on other corona virusesCOVID‐19 pandemic will persist in multiple periods of 1–2 yearsThe temperate and cold climate regions have higher infection rates than the tropical and arid climate regions [ABSTRACT FROM AUTHOR]
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- 2021
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27. Bifurcation analysis of a discrete ${SIRS}$ epidemic model with standard incidence rate.
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Hu, Zengyun, Chang, Linlin, Teng, Zhidong, and Chen, Xi
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BIFURCATION theory ,CHAOS synchronization ,ORBITS (Astronomy) ,COMPUTER simulation ,STANDARD deviations - Abstract
Discrete epidemic models are popularly used to detect the pathogenesis, spreading, and controlling of the diseases. The three-dimensional discrete ${SIRS}$ epidemic models are more suitable than the two-dimensional discrete models to describe the spreading characters of the diseases. In this paper, the complex dynamical behaviors of a three-dimensional discrete ${SIRS}$ epidemic model with standard incidence rate are discussed. We choose the time step size parameter as a bifurcation parameter, the existence, stability, and direction of Hopf bifurcation are proved by using the normal form theorem and bifurcation theory. Moreover, the numerical simulations not only illustrate our results, but they also exhibit the complex dynamical behaviors, such as the invariant cycle, period-7 orbits and period-12 orbits with more than one attractors and chaotic sets. The flip bifurcation caused by the step size parameter is also obtained by a numerical simulation. Most importantly, when the adequate contact rate and the death rate of the infective individuals are chosen as the bifurcation parameters, there also exist a Hopf bifurcation, a flip bifurcation, chaos, and strange attractors. These results provide significant information for the disease controlling when there appear complex dynamical behaviors in the epidemic model. [ABSTRACT FROM AUTHOR]
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- 2016
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28. Where Anthropogenic Activity Occurs, Anthropogenic Activity Dominates Vegetation Net Primary Productivity Change.
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Xie, Conghui, Wu, Shixin, Zhuang, Qingwei, Zhang, Zihui, Hou, Guanyu, Luo, Geping, and Hu, Zengyun
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EFFECT of human beings on climate change ,GRASSLANDS ,CLIMATE change ,LAND cover ,ARABLE land - Abstract
Anthropogenic activities and climate change affect the type, structure and function of ecosystems, resulting in important changes in vegetation net primary productivity (NPP). Therefore, in this study we used the vegetation photosynthesis model (VPM) to reveal the spatiotemporal variations in NPP in Xinjiang from 2000 to 2019. The impacts of climate change and anthropogenic activities on NPP changes were quantified and separated by the residual analysis-control variables (RES-CON) method. The results showed that the average NPP in Xinjiang increased by 17.77% from 2000 to 2019. Anthropogenic activities and climate change generally had a positive impact on NPP from 2000 to 2019. The most important anthropogenic activity was land use and land cover (LULC) transformation from grass to arable land, which significantly increased vegetation productivity. Regarding climate change, precipitation has played a significant role in promoting the productivity of vegetation. Overall, the average contribution of climate change (temperature and precipitation) to NPP variation (21.44%) is much greater than the contribution of anthropogenic activities (3.46%), but in areas where anthropogenic activities occur, the average contribution of anthropogenic activities to NPP variation (75.01%) is much greater than the average contribution of climate change (15.53%). Where there are no anthropogenic activities, the average contribution of climate change to NPP variation is 21.72%. In summary, anthropogenic activities are the main driver of NPP variation in areas where anthropogenic activities occur, while the total area in Xinjiang where climate change is the most important driver is larger than the total area where anthropogenic activities are the dominant driver. [ABSTRACT FROM AUTHOR]
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- 2022
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29. A New Machine Learning Approach in Detecting the Oil Palm Plantations Using Remote Sensing Data.
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Xu, Kaibin, Qian, Jing, Hu, Zengyun, Duan, Zheng, Chen, Chaoliang, Liu, Jun, Sun, Jiayu, Wei, Shujie, and Xing, Xiuwei
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OIL palm ,REMOTE sensing ,RANDOM forest algorithms ,MACHINE learning ,DEFORESTATION ,SUCCESSIVE approximation analog-to-digital converters - Abstract
The rapid expansion of oil palm is a major driver of deforestation and other associated damage to the climate and ecosystem in tropical regions, especially Southeast Asia. It is therefore necessary to precisely detect and monitor oil palm plantations to safeguard the ecosystem services and biodiversity of tropical forests. Compared with optical data, which are vulnerable to cloud cover, the Sentinel-1 dual-polarization C-band synthetic aperture radar (SAR) acquires global observations under all weather conditions and times of day and shows good performance for oil palm detection in the humid tropics. However, because accurately distinguishing mature and young oil palm trees by using optical and SAR data is difficult and considering the strong dependence on the input parameter values when detecting oil palm plantations by employing existing classification algorithms, we propose an innovative method to improve the accuracy of classifying the oil palm type (mature or young) and detecting the oil palm planting area in Sumatra by fusing Landsat-8 and Sentinel-1 images. We extract multitemporal spectral characteristics, SAR backscattering values, vegetation indices, and texture features to establish different feature combinations. Then, we use the random forest algorithm based on improved grid search optimization (IGSO-RF) and select optimal feature subsets to establish a classification model and detect oil palm plantations. Based on the IGSO-RF classifier and optimal features, our method improved the oil palm detection accuracy and obtained the best model performance (OA = 96.08% and kappa = 0.9462). Moreover, the contributions of different features to oil palm detection are different; nevertheless, the optimal feature subset performed the best and demonstrated good potential for the detection of oil palm plantations. [ABSTRACT FROM AUTHOR]
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- 2021
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30. Geographic Distribution of Desert Locusts in Africa, Asia and Europe Using Multiple Sources of Remote-Sensing Data.
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Chen, Chaoliang, Qian, Jing, Chen, Xi, Hu, Zengyun, Sun, Jiayu, Wei, Shujie, and Xu, Kaibin
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DESERT locust ,LEAF area index ,LEAF temperature ,LOGISTIC regression analysis ,REGRESSION analysis - Abstract
In history, every occurrence of a desert locust plague has brought a devastating blow to local agriculture. Analyses of the potential geographic distribution and migration paths of desert locusts can be used to better monitor and provide early warnings about desert locust outbreaks. By using environmental data from multiple remote-sensing data sources, we simulate the potential habitats of desert locusts in Africa, Asia and Europe in this study using a logistic regression model that was developed based on desert locust monitoring records. The logistic regression model showed high accuracy, with an average training area under the curve (AUC) value of 0.84 and a kappa coefficient of 0.75. Our analysis indicated that the temperature and leaf area index (LAI) play important roles in shaping the spatial distribution of desert locusts. A model analysis based on data for six environmental variables over the past 15 years predicted that the potential habitats of desert locust present a periodic movement pattern between 40°N and 30°S latitude. The area of the potential desert locust habitat reached a maximum in July, with a suitable area exceeding 2.77 × 10
7 km2 and located entirely between 0°N and 40°N in Asia-Europe and Africa. In December, the potential distribution of desert locusts reached its minimum area at 0.68 × 107 km2 and was located between 30°N and 30°S in Asia and Africa. According to the model estimates, desert locust-prone areas are distributed in northern Ethiopia, South Sudan, northwestern Kenya, the southern Arabian Peninsula, the border area between India and Pakistan, and the southern Indian Peninsula. In addition, desert locusts were predicted to migrate from east to west between these areas and in Africa between 10°N and 17°N. Countries in these areas should closely monitor desert locust populations and respond rapidly. [ABSTRACT FROM AUTHOR]- Published
- 2020
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31. Groundwater Depletion Estimated from GRACE: A Challenge of Sustainable Development in an Arid Region of Central Asia.
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Hu, Zengyun, Zhou, Qiming, Chen, Xi, Chen, Deliang, Li, Jianfeng, Guo, Meiyu, Yin, Gang, and Duan, Zheng
- Subjects
- *
ARID regions , *SUSTAINABLE development , *WATER security , *WATER supply , *SOIL moisture , *GROUNDWATER , *WATER storage , *SNOW - Abstract
Under climate change and increasing water demands, groundwater depletion has become regional and global threats for water security, which is an indispensable target to achieving sustainable developments of human society and ecosystems, especially in arid and semiarid regions where groundwater is a major water source. In this study, groundwater depletion of 2003–2016 over Xinjiang in China, a typical arid region of Central Asia, is assessed using the gravity recovery and climate experiment (GRACE) satellite and the global land data assimilation system (GLDAS) datasets. In the transition of a warm-dry to a warm-wet climate in Xinjiang, increases in precipitation, soil moisture and snow water equivalent are detected, while GRACE-based groundwater storage anomalies (GWSA) exhibit significant decreasing trends with rates between-3.61 ± 0.85 mm/a of CSR-GWSA and −3.10 ± 0.91 mm/a of JPL-GWSA. Groundwater depletion is more severe in autumn and winter. The decreases in GRACE-based GWSA are in a good agreement with the groundwater statistics collected from local authorities. However, at the same time, groundwater abstraction in Xinjiang doubled, and the water supplies get more dependent on groundwater. The magnitude of groundwater depletion is about that of annual groundwater abstraction, suggesting that scientific exploitation of groundwater is the key to ensure the sustainability of freshwater withdrawals and supplies. Furthermore, GWSA changes can be well estimated by the partial least square regression (PLSR) method based on inputs of climate data. Therefore, GRACE observations provide a feasible approach for local policy makers to monitor and forecast groundwater changes to control groundwater depletion. [ABSTRACT FROM AUTHOR]
- Published
- 2019
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32. Tackling resolution mismatch of precipitation extremes from gridded GCMs and site-scale observations: Implication to assessment and future projection.
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Li, Jianfeng, Gan, Thian Yew, Chen, Yongqin David, Gu, Xihui, Hu, Zengyun, Zhou, Qiming, and Lai, Yangchen
- Subjects
- *
METEOROLOGICAL precipitation , *INTERPOLATION , *GAGING , *GENERAL circulation model - Abstract
The resolution mismatch between GCMs and in-situ gauge observations is an issue that has to be addressed for assessments and projections of precipitation extremes. The impacts of using different strategies to address this issue on GCM assessments and projections are evaluated in this study. The differences of precipitation extremes derived from GCMs at the original gridded resolutions and site-scale observations can be mostly explained by resolution mismatch. As the spatial and temporal "discontinuous" nature of precipitation, consecutive dry days (precipitation intensity) estimated from GCM data over a grid are likely to be shorter (smaller) than in-situ observations. By interpolating GCMs and observations to a common resolution, areal differences are moderately reduced, but spatial correlations between GCMs and observations may not be necessarily improved. By statistically downscaling the GCM-derived precipitation extremes, the indices agree better with the in-situ observations substantially. Using interpolation or downscaling to resolve resolution mismatch in GCMs may result in contradictory projected changes in extremes. Downscaled precipitation extremes generally change in greater magnitude than interpolated extremes in the projections. • Resolution mismatch explains the differences in precipitation extremes between the gridded GCMs and site-scale observations. • Interpolation partially reduces the differences, and downscaling largely improves the performance of GCM-based extremes. • Using interpolation or downscaling to resolve resolution mismatch may result in contradictory projected changes in extremes. [ABSTRACT FROM AUTHOR]
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- 2020
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33. Scenario analysis of COVID-19 dynamical variations by different social environmental factors: a case study in Xinjiang.
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Fu R, Liu W, Wang S, Zhao J, Cui Q, Hu Z, Zhang L, and Wang F
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- Animals, Humans, Computer Simulation, Poverty, COVID-19 epidemiology, One Health, Communicable Diseases
- Abstract
Background: With the rapid advancement of the One Health approach, the transmission of human infectious diseases is generally related to environmental and animal health. Coronavirus disease (COVID-19) has been largely impacted by environmental factors regionally and globally and has significantly disrupted human society, especially in low-income regions that border many countries. However, few research studies have explored the impact of environmental factors on disease transmission in these regions., Methods: We used the Xinjiang Uygur Autonomous Region as the study area to investigate the impact of environmental factors on COVID-19 variation using a dynamic disease model. Given the special control and prevention strategies against COVID-19 in Xinjiang, the focus was on social and environmental factors, including population mobility, quarantine rates, and return rates. The model performance was evaluated using the statistical metrics of correlation coefficient (CC), normalized absolute error (NAE), root mean square error (RMSE), and distance between the simulation and observation (DISO) indices. Scenario analyses of COVID-19 in Xinjiang encompassed three aspects: different population mobilities, quarantine rates, and return rates., Results: The results suggest that the established dynamic disease model can accurately simulate and predict COVID-19 variations with high accuracy. This model had a CC value of 0.96 and a DISO value of less than 0.35. According to the scenario analysis results, population mobilities have a large impact on COVID-19 variations, with quarantine rates having a stronger impact than return rates., Conclusion: These results provide scientific insight into the control and prevention of COVID-19 in Xinjiang, considering the influence of social and environmental factors on COVID-19 variation. The control and prevention strategies for COVID-19 examined in this study may also be useful for the control of other infectious diseases, especially in low-income regions that are bordered by many countries., Competing Interests: The authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest., (Copyright © 2024 Fu, Liu, Wang, Zhao, Cui, Hu, Zhang, and Wang.)
- Published
- 2024
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34. Dynamic variations in and prediction of COVID-19 with omicron in the four first-tier cities of mainland China, Hong Kong, and Singapore.
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Ni X, Sun B, Hu Z, Cui Q, Zhang Z, and Zhang H
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- Humans, China epidemiology, Hong Kong epidemiology, Cities epidemiology, Pandemics, Singapore epidemiology, COVID-19 epidemiology
- Abstract
Background: The COVID-19 pandemic, which began in late 2019, has resulted in the devastating collapse of the social economy and more than 10 million deaths worldwide. A recent study suggests that the pattern of COVID-19 cases will resemble a mini-wave rather than a seasonal surge. In general, COVID-19 has more severe impacts on cities than on rural areas, especially in cities with high population density., Methods: In this study, the background situation of COVID-19 transmission is discussed, including the population number and population density. Moreover, a widely used time series autoregressive integrated moving average (ARIMA) model is applied to simulate and forecast the COVID-19 variations in the six cities. We comprehensively analyze the dynamic variations in COVID-19 in the four first-tier cities of mainland China (BJ: Beijing, SH: Shanghai, GZ: Guangzhou and SZ: Shenzhen), Hong Kong (HK), China and Singapore (SG) from 2020 to 2022., Results: The major results show that the six cities have their own temporal characteristics, which are determined by the different control and prevention measures. The four first-tier cities of mainland China (i.e., BJ, SH, GZ, and SZ) have similar variations with one wave because of their identical "Dynamic COVID-19 Zero" strategy and strict Non-Pharmaceutical Interventions (NPIs). HK and SG have multiple waves primarily caused by the input cases. The ARIMA model has the ability to provide an accurate forecast of the COVID-19 pandemic trend for the six cities, which could provide a useful approach for predicting the short-term variations in infectious diseases.Accurate forecasting has significant value for implementing reasonable control and prevention measures., Conclusions: Our main conclusions show that control and prevention measures should be dynamically adjusted and organically integrated for the COVID-19 pandemic. Moreover, the mathematical models are proven again to provide an important scientific basis for disease control., Competing Interests: The authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest., (Copyright © 2023 Ni, Sun, Hu, Cui, Zhang and Zhang.)
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- 2023
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35. Modeling and analysis of the transmission dynamics of cystic echinococcosis: Effects of increasing the number of sheep.
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He Y, Cui Q, and Hu Z
- Subjects
- Animals, Sheep, Dogs, Basic Reproduction Number, Uncertainty, Echinococcosis epidemiology, Echinococcosis veterinary
- Abstract
A transmission dynamics model with the logistic growth of cystic echinococcus in sheep was formulated and analyzed. The basic reproduction number was derived and the results showed that the global dynamical behaviors were determined by its value. The disease-free equilibrium is globally asymptotically stable when the value of the basic reproduction number is less than one; otherwise, there exists a unique endemic equilibrium and it is globally asymptotically stable. Sensitivity analysis and uncertainty analysis of the basic reproduction number were also performed to screen the important factors that influence the spread of cystic echinococcosis. Contour plots of the basic reproduction number versus these important factors are presented, too. The results showed that the higher the deworming rate of dogs, the lower the prevalence of echinococcosis in sheep and dogs. Similarly, the higher the slaughter rate of sheep, the lower the prevalence of echinococcosis in sheep and dogs. It also showed that the spread of echinococcosis has a close relationship with the maximum environmental capacity of sheep, and that they have a remarkable negative correlation. This reminds us that the risk of cystic echinococcosis may be underestimated if we ignore the increasing number of sheep in reality.
- Published
- 2023
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36. The impact of social support on the quality of life among older adults in China: An empirical study based on the 2020 CFPS.
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Shen T, Li D, Hu Z, Li J, and Wei X
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- Aged, China, Female, Humans, Male, Rural Population, Social Support, Activities of Daily Living, Quality of Life
- Abstract
Background: As aging issues become serious, how to guarantee and improve the quality of life among older adults has become a hot topic in China. This article is aimed to discuss the impact of formal and informal social support on the quality of life among older adults and the differences in gender and urban-rural areas., Methods: The data used in this article are from the 2020 China Family Panel Studies (CFPS). Quality of life is measured from three dimensions of life: satisfaction, self-rated health, and mental state. This article uses the ordered logistic regression model to analyze the impact of social support on life satisfaction and self-rated health, and the binary logistic regression model to analyze the impact of social support on the mental state. The method of Shapley value decomposition further analyzes the contribution of influencing factors to the quality of life., Results: The activities of daily living (ADL) and income significantly impact the quality of life among older adults. Formal and informal social support positively improved the quality of life among older adults, but the effect of informal social support is greater than that of formal social support. The male older adults are significantly better than the female adults across all three dimensions of quality of life. The mental state of urban older adults is better than that of rural older adults., Conclusion: Formal and informal social support should be strengthened to improve the income of older adults. Older adults should be encouraged to participate in social activities and good interpersonal relationships should be established actively. Female older adults should be paid more attention. The proportion of female older adults participating in insurance should be increased, and the family and intergenerational care burden for female older adults should be reduced. The leisure life of urban older adults should be enriched. The basic social insurance and health service systems in rural areas should be improved., Competing Interests: The authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest., (Copyright © 2022 Shen, Li, Hu, Li and Wei.)
- Published
- 2022
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37. Empirical Study of Monthly Economic Losses Assessments for "Standard Unit Lockdown" Due to COVID-19.
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Zhang H, You S, Zhang M, Chen A, Hu Z, Liu Y, Liu D, Yuan P, and Tan Y
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- Brazil, Communicable Disease Control, Cost-Benefit Analysis, Humans, Pandemics, United States, COVID-19 epidemiology, COVID-19 prevention & control
- Abstract
Background: The pandemic of COVID-19 has been shaping economic developments of the world. From the standpoint of government measures to prevent and control the epidemic, the lockdown was widely used. It is essential to access the economic losses in a lockdown environment which will provide government administration with a necessary reference for decision making in controlling the epidemic., Methods: We introduce the concept of "standard unit incident" and an economic losses assessment methodology for both the standard and the assessed area. We build a "standard unit lockdown" economic losses assessment system and indicators to estimate the economic losses for the monthly lockdown. Using the comprehensive assessment system, the loss infected coefficient of monthly economic losses during lockdown in the 40 countries has been calculated to assess the economic losses by the entropy weighting method (EWM) with data from the CSMAR database and CDC website., Results: We observe that countries in North America suffered the most significant economic losses due to the epidemic, followed by South America and Europe, Asia and Africa, and Oceania and Antarctica suffered relatively minor economic losses. The top 10 countries for monthly economic losses during lockdown were the United States, India, Brazil, France, Turkey, Russia, the United Kingdom, Italy, Spain, and Germany. The United States suffered the greatest monthly economic losses under lockdown ($65.3 billion), roughly 1.5 times that of China, while Germany suffered the least ($56.4 billion), roughly 1.3 times that of China., Conclusion: Lockdown as a control and mitigation strategy has great impact on the economic development and causes huge economic losses. The economic impact due to the pandemic has varied widely among the 40 countries. It will be important to conduct further studies to compare and understand the differences and the reasons behind., Competing Interests: The authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest., (Copyright © 2022 Zhang, You, Zhang, Chen, Hu, Liu, Liu, Yuan and Tan.)
- Published
- 2022
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38. Spatiotemporal changes, trade-offs, and synergistic relationships in ecosystem services provided by the Aral Sea Basin.
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Chen CL, Chen X, Qian J, Hu Z, Liu J, Xing X, Yimamaidi D, Zhakan Z, Sun J, and Wei S
- Abstract
Intense human activities in the Aral Sea Basin have changed its natural distribution of land use. Although they provide certain economic benefits, these anthropogenic influences have led to the rapid shrinkage of the Aral Sea, severely affecting the region's ecosystem. However, the spatiotemporal variability of the Aral Sea Basin's Ecosystem Service Values (ESVs) is not well understood. In this study, we used 300-meter resolution land use maps from 1995, 2005, and 2015 and the Patch-generating Land Use Simulation (PLUS) model to predict the future land use patterns of the Aral Sea Basin in 2025. Simultaneously, we divided the Aral Sea Basin into three regions (upstream, midstream, and downstream) and evaluated the dynamic responses of their ESVs to Land Use and Land Cover (LULC) changes. The changes in the types of ecosystem services provided by the Aral Sea Basin, their trade-off, and synergistic relationships were analyzed by weighting their associations. The results showed that from 1995 to 2025, the grassland, urban, and cropland areas in the Aral Sea Basin will expand rapidly, while the areas covered by water bodies will shrink rapidly, causing a total loss of 31.97 billion USD. The downstream loss of 27.79 billion USD of the total amount is mainly caused by the conversion of water bodies to bare land. The ESVs of the middle region will increase by 6.81 billion USD, mainly due to the large amount of water extracted from the Amu Darya and Syr Darya Rivers in the middle regions of the Aral Sea Basin that are used to reclaim cultivated land and expand urban areas. The ESVs and areas experiencing land use changes in the upper regions are relatively small. At the same time, our results show that biodiversity, food production, and water regulation are the major ecosystem service functions, and account for 79.46% of the total ESVs. Of the ecosystem service relationships in the Aral Sea Basin, synergy accounts for 55.56% of the interactions, with a fewer amount of trade-off exchanges. This synergy mainly exists in the relationships involving water regulation, waste treatment and recreation, and culture and tourism. We propose protection measures that will coordinate eco-environmental protection efforts with socioeconomic development in the region in order to achieve the United Nations' sustainable development goals., Competing Interests: Jun Liu is an employee of the TripleSAI Technology, Shenzhen, China., (©2021 Chen et al.)
- Published
- 2021
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