Objective To analyze the substitutions at amino acid residues of neuraminidases ( NAs) in influenza B virus strains isolated in Jiangsu province from 2010 to 2012 and to further understand the genetic evolution of NAs in those influenza B virus strains .Methods Forty strains of influenza B virus isolated in Jiangsu province from 2010 to 2012 were screened out for this study .A two-step reverse transcrip-tion PCR ( RT-PCR) was performed to amply the gene fragments encoding the neuraminidases of influenza B virus strains.The PCR products were purified and then sequenced in an ABI 3730XL Genetic Analyzer.The evolutionary characteristics of NA gene were analyzed by using DNAStar , Bioedit, MEGA 5.0 and BEAST 1.8.0 softwares.Results The phylogenetic tree analysis of the NA genes showed that the NAs of 28 Vic-toria strains were derived from the Yamagata lineage .There were reassortments between the Victoria lineage-HA and theYamagata lineage-NA.Some of the strains added a glycosylation site at position 462.No substitu-tion was found in important enzyme active sites and neuraminidase inhibitor resistant sites .The Bayesian MCMC analysis showed that the estimated mean evolutionary rate for NA gene was 1.74×10-3(95%HPD:1.46×10-3-2.06×10-3) substitutions/site/year.The dN/dS ratio (ω), an indicator of selective pressure, was 0.24.Conclusion The important amino acid sites of NA were relatively conservative and the evolution -ary rate for NA gene was low .The dN/dS ratio was less than one , indicating that the NA gene was under pu-rifying selection .

Objective: To investigate the spatial clustering characteristics of varicella public health emergency events in Nanjing City from 2017 to 2022, so as to provide the evidence for the development of varicella prevention and control strategies. Methods: Data of varicella public health emergency events in Nanjing City from 2017 to 2022 were collected through Emergency Public Health Management Information System of Chinese Disease Prevention and Control Information System. The software ArcGIS 10.2 was employed for trend-surface analysis, spatial autocorrelation analysis and hotspot analysis to understand the spatial clustering characteristics of varicella public health emergency events. Results: A total of 84 varicella public health emergency events were reported in Nanjing City from 2017 to 2022, with an average attack rate of 2.53% (2 558 cases). Ⅳ-level events were predominant, accounting for 90.48% (76 events). The trend-surface analysis showed lower incidence of varicella public health emergency events in the west of Nanjing City and higher in the east, and lower in the north and higher in the south. The global spatial autocorrelation analysis showed that there was a positive spatial correlation in varicella public health emergency events in 2017 and 2019, indicating spatial clustering (P<0.05). The hot spots were Jiangning District, Gaochun District, Yuhuatai District and Jianye District. Conclusion The incidence of varicella public health emergency events in Nanjing City from 2017 to 2022 has spatial aggregation, with a concentration in suburban areas such as Jiangning District and Gaochun District.

Objective:To compare the self-evaluated learning behavior and achievement of eight-year-program clinical medical students on online and offline problem-based learning (PBL), and to provide references and suggestions for successful implementation of online PBL teaching.Methods:During the three semesters of September 2020 to January 2022, a survey was performed on 100 clinical medical students of 2018 eight-year program on online or offline PBL teaching in Xiangya School of Medicine, Central South University. At the end of PBL courses, the students received questionnaires to self-assess their learning behavior and achievement in online or offline PBL teaching. The data were analyzed using the paired rank sum test with the use of SPSS 26.0.Results:Before class, there were no significant differences in learning behaviors including preparation time, communication with classmates, and materials collecting and sorting between students on online and offline PBL teaching ( P>0.05). In class, no significant differences were found in students' initiative of speaking and degree of satisfaction with classmates' speaking between online and offline teaching ( P>0.05), but the students on offline teaching showed significantly better concentration of attention ( Z=-4.24, P<0.001), listening to classmates' speeches ( Z=-3.42, P=0.001), and classmates' interaction ( Z=-3.11, P=0.002) compared with those on online teaching. No significant differences were observed between online and offline PBL teaching in students' self-evaluated learning achievements including improvements in autonomous learning ability, problem-solving ability, and literature inquiry skills ( P>0.05). Conclusion:Students on online PBL teaching have generally as good pre-class preparation and in-class learning performance as those on offline PBL teaching, indicating that the online PBL mode can be well implemented, and it can also ensure almost the same learning achievement as offline teaching.

Objective:To analyze the online learning behaviors and learning results of students under different teaching modes with different learning motivations, and to provide a reference for optimizing the development of online teaching.Methods:Samples of students taking the physiology small private online course (SPOC) in 2019 and 2020, and students taking the massive open online courses (MOOC) in the same year were selected in the study to discuss the differences in learning behaviors of students under different teaching modes and learning effects on students with different learning motivations. The online learning behaviors of students were analyzed based on their learning engagement, interactive behavior and learning motivation. SPSS 25.0 was used to analyze the data with statistical methods such as function calculation, frequency statistics, regression analysis, rank sum test, correlation test and chi-square test.Results:The learning participation level ( z=14.36, P<0.001), and the human-machine and interpersonal learning interaction level ( z=-11.70, -16.18, both P<0.001) of SPOC learners in 2020 were higher than those in 2019. The overall interactive level was moderately correlated with performances of students ( r=0.42, 0.52, both P<0.001), and the correlation between interpersonal behavior and grades was much more stronger ( r=0.60, 0.55, both P<0.001). The performance composition of SPOC and MOOC learners in 2019 was completely different ( χ2=857.45, P<0.001). The learning effect of externally motivated students was significantly better than that of internally motivated students ( z=-28.42, P<0.001). Conclusion:The teaching mode adopted by the school can affect the learning effect by influencing the students' online learning engagement and interactive behavior. Besides, students' own learning motivation also plays a key role in their academic performance.

Objective:To evaluate the teaching effectiveness of independent experimental design from students' active learning behavior, and further provide the basis for advancing the reform of functional experimental teaching and teaching quality.Methods:In June 2019, 186 undergraduates (5-year-programme and 8-year-programme) of Xiangya School of Medicine were included in the teaching research. Self-administered questionnaires were applied to characterize students' active learning behavior in independent experimental design education. Spearman rank correlation analysis and Logistic regression analysis were used in the study. SPSS 23.0 was used for descriptive analysis of the data.Results:During the independent experimental design, 85.0%(158/186) of the students thought it was necessary and important to conduct independent experimental design education; 72.6%(135/186) of the students tentatively raised new scientific questions; 97.8%(182/186) of the students actively searched literature; 77.4%(144/186) of the students participated in reply positively. The value of correlation coefficient of actively learning behavior "tentatively raising new science questions" and teaching effectiveness "improving the ability of scientific thinking" was 0.81. And only 42.5%(79/186) of the students agreed that students needed to summarize after reporting.Conclusion:Independent experimental design education is welcomed and widely accepted by students, which has effectively improved the capacity for scientific research and innovation spirit of students. Whether students' active learning behavior can be fully mobilized in the education practice is closely related to the teaching effect. And the cultivation of leadership and leading consciousness still need to be improved.