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Global COVID-19 Pandemic Waves: Limited Lessons Learned Worldwide over the Past Year

Engineering 2022年第6期8卷 91-98页

作者： Yongyue Wei Jinxing Guan Xiao Ning Yuelin Li Liangmin Wei Sipeng Shen Ruyang Zhang Yang Zhao Hongbing Shen Feng Chen Department of Epidemiology and Biostatistics School of Public HealthNanjing Medical UniversityNanjing 211166China China International Cooperation Center for Environment and Human Health&Center for Global Health Nanjing Medical UniversityNanjing 211166China Department of Biomedical Engineering School of Biological Science and Medical EngineeringSoutheast UniversityNanjing 210096China Institute for Social and Economic Research and Policy Columbia UniversityNew YorkNY 10027USA

The occurrence of coronavirus disease 2019(COVID-19)was followed by a small burst of cases around the world;afterward,due to a series of emergency non-pharmaceutical interventions(NPIs),the increas-ing number of confirmed cases slowed down in many ***,the lifting of control measures by the government and the public’s loosening of precautionary behaviors led to a sudden increase in cases,arousing deep concern across the *** deep concern across the *** study evaluates the situation of the COVID-19 pandemic in countries and territories worldwide from January 2020 to February *** to the time-varying reproduction number(R(t))of each country or territory,the results show that almost half of the countries and territories in the world have never controlled the *** the countries and territories that had once contained the occurrence,nearly half failed to maintain their prevention and control,causing the COVID-19 pandemic to rebound across the world—resulting in even higher waves in half of the rebounding countries or *** work also proposes and uses a time-varying country-level transmission risk score(CTRS),which takes into account both R(t)and daily new cases,to demonstrate country-level or territory-level transmission potential and ***-varying hierarchical clustering of time-varying CTRS values was used to successfully reveal the countries and territories that contributed to the recent aggravation of the global pandemic in the last quarter of 2020 and the beginning of 2021,and to identify countries and territories with an increasing risk of COVID-19 transmission in the near ***,a regression analysis indicated that the introduction and relaxation of NPIs,including workplace closure policies and stay-at-home requirements,appear to be associated with recent global transmission *** conclu-sion,a systematic evaluation of the global COVID-19 pandemic over the past year indicates that

关键词： COVID-19 Global pandemic prevention and control effect

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effects of Different Herbicides on Maize Growth and Weed control in Maize Fields

引用

Agricultural Science & Technology 2017年第9期18卷 1738-1740页

作者： Yanyan CHEN Yang YANG Jing ZHOU Guiyuan MENG College of Agriculture and Biotechnology Hunan University of HumanitiesScience and Technology Collaborative Innovation Center for Farmland Weeds control Technology and Application in Hunan Province

effects of four herbicides(paraquat, acetochlor, nicosulfuron and atrazine) on the growth of maize and control effect of plant quantity and fresh weight of weeds were studied. The results showed that 15 days after spraying the herbicides on weeds,the prevention and control effect of paraquat on weeds was the optimum, and its effects on the plant quantity and fresh weight of weeds were above 81.57%; the prevention and control effect of acetochlor on weeds was the second best; the prevention and control effect of atrazine on weeds was the worst, and its effects on the plant quantity and fresh weight of weeds were only 51.04% and 37.86%. After 30 or 45 days, the prevention and control effect of atrazine and nicosulfuron on weeds in the maize fields was better than the other herbicides, and their effects on the plant quantity and fresh weight of weeds were higher than 70.00% and 85.00%. Acetochlor and paraquat had certain phytotoxicity to the growth of maize after about 15 days, and its leaves became yellow and grew slowly. On the whole, nicosulfuron had good prevention and control effect on weeds and had no phytotoxicity to the growth of maize.

关键词： Maize Herbicides Weeds Growth prevention and control effect

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