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227 results on '"Liu, Fengfeng"'

7. Seroepidemiology of enterovirus A71 infection in prospective cohort studies of children in southern China, 2013-2018

Author

Yang, Juan, Liao, Qiaohong, Luo, Kaiwei, Liu, Fengfeng, Zhou, Yonghong, Zou, Gang, Huang, Wei, Yu, Shuanbao, Wei, Xianglin, Zhou, Jiaxin, Dai, Bingbing, Qiu, Qi, Altmeyer, Ralf, Hu, Hongan, Paireau, Juliette, Luo, Li, Gao, Lidong, Nikolay, Birgit, Hu, Shixiong, Xing, Weijia, Wu, Peng, van Doorn, H. Rogier, Horby, Peter W., Simmonds, Peter, Leung, Gabriel M., Cowling, Benjamin J., Cauchemez, Simon, and Yu, Hongjie

Published
2022
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15. The transfer and decay of maternal antibodies against enterovirus A71, and dynamics of antibodies due to later natural infections in Chinese infants: a longitudinal, paired mother–neonate cohort study

Author

Wei, Xianglin, Yang, Juan, Gao, Lidong, Wang, Lili, Liao, Qiaohong, Qiu, Qi, Luo, Kaiwei, Yu, Shuanbao, Zhou, Yonghong, Liu, Fengfeng, Chen, Qi, Zhang, Juanjuan, Dai, Bingbing, Yang, Hao, Zhou, Jiaxin, Xing, Weijia, Chen, Xinhua, He, Min, Ren, Lingshuang, Guo, Jinxin, Luo, Li, Wu, Peng, Chen, Zhiyong, van Doorn, H Rogier, Cauchemez, Simon, Cowling, Benjamin J, and Yu, Hongjie

Published
2021
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16. Distributed Optimal Power Flow Analysis of Active Distribution Networks Based on Intelligent Partition Strategy.

Author

LIU Fengfeng and XUE Dong

Subjects
OPTIMIZATION algorithms, ELECTRICAL load, ENERGY management, INTELLIGENT networks, PROBLEM solving, DISTRIBUTED algorithms
Abstract

With the increasing penetration of distributed energy in power systems, the optimal power flow (OPF) analysis-based distribution network energy management system faces challenges such as high data dimensionality, long solution time, and large computational load. In response to these challenges, this paper aims to use the alternating direction method of multipliers (ADMM) to solve the OPF problem of active distribution systems in a fully distributed fashion. Considering the impact of distribution system partitioning on the performance of distributed algorithms, a data-driven network partitioning method based on measurement data is proposed to accelerate the convergence rate of the optimization algorithm. Moreover, different from traditional ADMM algorithms that rely more or less on certain global information, this paper integrates a consensus-based method to coordinate the balance problem at the interface between regions, thereby achieving a fully distributed solution to the OPF problem. In addition, this paper employs the LinDistFlow AC power flow approximation model to resolve the non-convexity challenges of the OPF problem. Finally, the effectiveness of the proposed method is verified through tests on IEEE distribution network cases of different sizes, and its performance in terms of error accuracy and computation time of the optimization algorithm is superior in comparison to other partitioning methods. [ABSTRACT FROM AUTHOR]

Published
2024
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18. Spectrum of Enterovirus Serotypes Causing Uncomplicated Hand, Foot, and Mouth Disease and Enteroviral Diagnostic Yield of Different Clinical Samples

Author

Gao, Lidong, Zou, Gang, Liao, Qiaohong, Zhou, Yonghong, Liu, Fengfeng, Dai, Bingbing, Liu, Jia, Chen, Zhiyong, Xing, Weijia, Yang, Le, Liang, Hong, Zhang, Yi, Chen, Zhenhua, Luo, Li, Li, Qing, Luo, Kaiwei, Wu, Peng, Mo, Xiaowei, Wang, Lili, Lan, Ke, Horby, Peter W., Cowling, Benjamin J., Simmonds, Peter, Altmeyer, Ralf, van Doorn, H. Rogier, and Yu, Hongjie

Published
2018

25. Emerging Enteroviruses Causing Hand, Foot and Mouth Disease, China, 2010-2016

Author

Li, Yu, Chang, Zhaorui, Wu, Peng, Liao, Qiaohong, Liu, Fengfeng, Zheng, Yaming, Luo, Li, Zhou, Yonghong, Chen, Qi, Yu, Shuanbao, Guo, Chun, Chen, Zhenhua, Long, Lu, Zhao, Shanlu, Yang, Bingyi, Yu, Hongjie, and Cowling, Benjamin J.

Subjects
Enterovirus infections -- Risk factors, Foot -- Health aspects, Hand -- Health aspects, Mouth -- Health aspects, Health
Abstract

Hand, foot and mouth disease (HFMD) is a common childhood infectious disease caused by enteroviruses (1). In China, HFMD cases must be reported to the Notifiable Infectious Diseases Reporting Information [...]

Published
2018
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26. Epidemiology of Recurrent Hand, Foot and Mouth Disease, China, 2008-2015

Author

Huang, Jiao, Liao, Qiaohong, Ooi, Mong How, Cowling, Benjamin J., Chang, Zhaorui, Wu, Peng, Liu, Fengfeng, Li, Yu, Luo, Li, Yu, Shuanbao, Yu, Hongjie, and Wei, Sheng

Subjects
Coxsackievirus infections -- Complications and side effects -- Diagnosis, Recurrence (Disease) -- Research, Epidemiology -- Analysis, Health
Abstract

Hand, foot and mouth disease (HFMD) is a common childhood infectious disease that is mainly caused by enterovirus A71 (EV-A71), coxsackievirus A16 (CV-A16), and CV-A6 (1). Most HFMD patients exhibit [...]

Published
2018
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27. Preventing Child Sexual Abuse Early: Preschool Teachers' Knowledge, Attitudes, and Their Training Education in China

Author

Zhang, Wenjing, Chen, Jingqi, and Liu, Fengfeng

Abstract

This study is aimed to examine preschool teachers' knowledge of, attitudes about, and training related to child sexual abuse (CSA) prevention in Beijing, China. Two hundred and forty-five preschool teachers were administered the 16-item questionnaire that contained questions on CSA prevention knowledge, attitudes, and teacher training. Results showed that Chinese preschool teachers had limited knowledge on CSA prevention (M = 4.86, SD = 2.12). Less than 5% of the teachers ever attended CSA prevention training programs. Preschool teachers' training on CSA prevention was the significant factor for their knowledge and attitudes. To help protect children against sexual abuse, there is an urgent need to develop appropriate prevention training programs for preschool teachers in China.

Published
2015
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31. Comparison of Patients Hospitalized With Influenza A Subtypes H7N9, H5N1, and 2009 Pandemic H1N1

Author

Wang, Chen, Yu, Hongjie, Horby, Peter W., Cao, Bin, Wu, Peng, Yang, Shigui, Gao, Hainv, Li, Hui, Tsang, Tim K., Liao, Qiaohong, Gao, Zhancheng, Ip, Dennis K. M., Jia, Hongyu, Jiang, Hui, Liu, Bo, Ni, Michael Y., Dai, Xiahong, Liu, Fengfeng, Van Kinh, Nguyen, Liem, Nguyen Thanh, Hien, Tran Tinh, Li, Yu, Yang, Juan, Wu, Joseph T., Zheng, Yaming, Leung, Gabriel M., Farrar, Jeremy J., Cowling, Benjamin J., Uyeki, Timothy M., and Li, Lanjuan

Published
2014
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36. Changing epidemiology of hand, foot, and mouth disease in China, 2013−2019:a population-based study

Author

Hong, Jie, Liu, Fengfeng, Qi, Hongchao, Tu, Wei, Ward, Michael P., Ren, Minrui, Zhao, Zheng, Su, Qing, Huang, Jiaqi, Chen, Xi, Le, Jiaxu, Ren, Xiang, Hu, Yi, Cowling, Ben, Li, Zhongjie, Chang, Zhaorui, Zhang, Zhijie, Hong, Jie, Liu, Fengfeng, Qi, Hongchao, Tu, Wei, Ward, Michael P., Ren, Minrui, Zhao, Zheng, Su, Qing, Huang, Jiaqi, Chen, Xi, Le, Jiaxu, Ren, Xiang, Hu, Yi, Cowling, Ben, Li, Zhongjie, Chang, Zhaorui, and Zhang, Zhijie

Abstract

Background: Hand, foot, and mouth disease (HFMD) is an important public health problem. A monovalent EV-A71 vaccine was launched in China in 2016. Previous studies showed that inactivated monovalent EV-A71 vaccines were highly efficient against HFMD associated with EV-A71 but not against HFMD with other etiologies, leading to a hypothesis that the introduction of EV-A71 vaccines might change the pathogen spectrum and epidemiological trend of HFMD. In this study, we described for the first time the changing epidemiological characteristics of HFMD after the launch of the EV-A71 vaccine. Methods: We extracted individual-based epidemiological data on HFMD cases reported to the Chinese Center for Disease Control and Prevention between January 2013 and December 2019. We described the changing epidemiological characteristics of HFMD before and after vaccine launch according to the distribution of diseases characteristics (demographic, temporal, and geographical) and evaluated the potential changes in risk factors of severe patients. All analyses were stratified by the phase before and after vaccine launch, and by enterovirus serotype. Findings: During 2013−2019, 15,316,710 probable cases of HFMD were reported. Of these, 787,197 (5·1%) were laboratory confirmed and 76,982 (0·5%) were severe. After the launch of the EV-A71 vaccine, the median age of HFMD patients infected with EV-A71 increased from 2·24 years (IQR:1·43, 3·56) to 2·81 years (IQR:1·58, 4·01). The proportion of patients less than 3 years of age decreased while the proportion of patients 3−5 years of age increased. There was a large decrease (60·7%) in the proportion of severe cases as well as a decline (28·3%) in HFMD patients infected with EV-A71. After the launch of the EV-A71 vaccine, the severe illness rate and mortality rate of HFMD patients in all age groups has decreased sharply, 62·20% and 83·78% respectively. The timing of the HFMD epidemic peak was delayed (1-2 months). After the launch of EV-A71 v

Published
2022

39. Assessing asymptomatic, pre-symptomatic and symptomatic transmission risk of SARS-CoV-2

Author

Wu, Peng, Liu, Fengfeng, Chang, Zhaorui, Lin, Yun, Ren, Minrui, Zheng, Canjun, Li, Yu, Peng, Zhibin, Qin, Yin, Yu, Jianxing, Geng, Mengjie, Yang, Xiaokun, Zhao, Hongting, Li, Zhili, Zhou, Sheng, Ran, Lu, Cowling, Benjamin J, Lai, Shengjie, Chen, Qiulan, Wang, Liping, Tsang, Tim K, and Li, Zhongjie

Abstract

BACKGROUND: The relative contributions of asymptomatic, presymptomatic, and symptomatic transmission of severe acute respiratory syndrome coronavirus 2 have not been clearly measured, although control measures may differ in response to the risk of spread posed by different types of cases. METHODS: We collected detailed information on transmission events and symptom status based on laboratory-confirmed patient data and contact tracing data from 4 provinces and 1 municipality in China. We estimated the variation in risk of transmission over time and the severity of secondary infections by symptomatic status of the infector. RESULTS: There were 393 symptomatic index cases with 3136 close contacts and 185 asymptomatic index cases with 1078 close contacts included in the study. The secondary attack rates among close contacts of symptomatic and asymptomatic index cases were 4.1% (128 of 3136) and 1.1% (12 of 1078), respectively, corresponding to a higher transmission risk from symptomatic cases than from asymptomatic cases (odds ratio, 3.79; 95% confidence interval, 2.06-6.95). Approximately 25% (32 of 128) and 50% (6 of 12) of the infected close contacts were asymptomatic from symptomatic and asymptomatic index cases, respectively, while more than one third (38%) of the infections in the close contacts of symptomatic cases were attributable to exposure to the index cases before symptom onset. CONCLUSIONS: Asymptomatic and presymptomatic transmissions play an important role in spreading infection, although asymptomatic cases pose a lower risk of transmission than symptomatic cases. Early case detection and effective test-and-trace measures are important to reduce transmission.

Published
2021

40. High‐Temperature Stability Amorphous Ternary AlBN Dielectric Films on N++GaN.

Author

Liu, Fengfeng, Li, Yuxiong, Devaux, Xavier, Lu, Yuan, Luo, Yi, Sui, Zhanpeng, Cai, Yong, and Jiang, Chunping

Subjects
DIELECTRIC thin films, PULSED laser deposition, THIN films, DIELECTRIC films, STRAY currents, PERMITTIVITY
Abstract

Dielectric films have played a vital role in the development of micro‐ and nanoelectronic devices over the past decades. However, the stability of current dielectrics under extreme high‐temperature conditions is still a major shortcoming to be overcome. Herein, the successful fabrication of high‐quality amorphous ternary AlBN dielectric films on n++GaN substrates by pulsed laser deposition (PLD) at room temperature (25 ± 2 °C) is reported. Systematic characterizations on the morphology, structure, chemical composition, and band offsets properties of the fabricated films reveal that both as‐deposited and 800 °C postdeposition annealing (PDA) thin films are amorphous and exhibit good physical and electrical properties. Large band offsets (>2.0 eV), high dielectric constants (>10), and low leakage currents are achieved in both cases. Furthermore, the leakage current density in the Au/AlBN/n++GaN junctions of 800 °C PDA thin films is reduced by approximately one order of magnitude compared with those of as‐deposited thin films. The demonstration of these excellent properties indicates that the amorphous AlBN dielectric thin films are promising candidates for integrated dielectric layers in electronic devices for harsh environment applications. [ABSTRACT FROM AUTHOR]

Published
2022
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43. Intra-area factors dominate the spatio-temporal transmission heterogeneity of hand, foot, and mouth disease in China: A modelling study

Author

Hong, Shangzhi, primary, Liu, Fengfeng, additional, Bauer, Cici, additional, Chen, Yue, additional, Tu, Wei, additional, Zhang, Jun, additional, Hu, Jian, additional, Zhang, Wenyi, additional, Hu, Yi, additional, Lynn, Henry S., additional, Li, Yu, additional, Chang, Zhaorui, additional, Li, Zhongjie, additional, and Zhang, Zhijie, additional

Published
2021
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44. Basic Reproduction Number of Enterovirus 71 and Coxsackievirus A16 and A6: Evidence From Outbreaks of Hand, Foot, and Mouth Disease in China Between 2011 and 2018

Author

Zhang, Zhong, Liu, Yang, Liu, Fengfeng, Ren, Minrui, Nie, Taoran, Cui, Jinzhao, Chang, Zhaorui, and Li, Zhongjie

Abstract

BACKGROUND: Enterovirus 71 (EV-A71), coxsackievirus A16 (CV-A16), and coxsackievirus A6 (CV-A6) are common serotypes causing hand, foot, and mouth disease (HFMD). Analyses on the basic reproduction number (R0) of common pathogens causing HFMD are limited and there are no related studies using field data from outbreaks in mainland China. METHODS: We estimated the pathogen-specific basic reproduction number based on laboratory-confirmed HFMD outbreaks (clusters of ≥10 HFMD cases) reported to the national surveillance system between 2011 and 2018. The reproduction numbers were calculated using a mathematical model and the cumulative cases during the initial growth periods. RESULTS: This study included 539 outbreaks, of which 198 were caused by EV-A71, 316 by CV-A16, and 25 by CV-A6. All 10 417 cases involved were children. Assuming the outbreaks occurred in closed systems and the incubation period is 5 days, the median (interquartile range [IQR]) R0 estimates of EV-A71, CV-A16, and CV-A6 were 5.06 (2.81, 10.20), 4.84 (3.00, 9.00), and 5.94 (3.27, 10.00). After adjusting for seroprevalences, the R0 (IQR) estimates for EV-A71, CV-A16 (optimistic and conservative scenarios), and CV-A6 were 12.60 (7.35, 25.40), 9.29 (6.01, 19.20), 15.50 (9.77, 30.40), and 25.80 (14.20, 43.50), respectively. We did not observe changes in the R0 of EV-A71 after vaccine licensure (P = .67). CONCLUSIONS: HFMD is highly transmissible when caused by the 3 most common serotypes. In mainland China, it primarily affects young children. Although a vaccine became available in 2016, we have not yet observed any related changes in the disease dynamics.

Published
2020

46. Assessing Asymptomatic, Presymptomatic, and Symptomatic Transmission Risk of Severe Acute Respiratory Syndrome Coronavirus 2

Author

Wu, Peng, primary, Liu, Fengfeng, additional, Chang, Zhaorui, additional, Lin, Yun, additional, Ren, Minrui, additional, Zheng, Canjun, additional, Li, Yu, additional, Peng, Zhibin, additional, Qin, Yin, additional, Yu, Jianxing, additional, Geng, Mengjie, additional, Yang, Xiaokun, additional, Zhao, Hongting, additional, Li, Zhili, additional, Zhou, Sheng, additional, Ran, Lu, additional, Cowling, Benjamin J, additional, Lai, Shengjie, additional, Chen, Qiulan, additional, Wang, Liping, additional, Tsang, Tim K, additional, and Li, Zhongjie, additional

Published
2021
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