Objective To reconstruct sparse views CT image based on defective projection data.Methods The position of bad bins in detector determined whether the linear interpolation was applied to the defective projection data.Moreover,reconstruction of air pixels in CT image was achieved rapidly and accurately.Results he experimental results showed that the proposed method could solve the problem from classical ART-TV method that the robustness was unstable due to the different positions of bad bin in CT detector.Conclusion Compared to analytical reconstruction methods,iterative methods can solve the reconstruction problems in this modality so that the radiologist is facilitated to perform image processing and quantitative analysis.

Objective: To investigate the pedestrian traffic safety behaviors of primary and secondary school students in Xiacheng District of Hangzhou,and to provide reference for formulating traffic safety strategy. Methods: In October 2015,nine campuses of six schools in Xiacheng District were selected to observe the pedestrian traffic safety behaviors of the primary and secondary school students walking to and from school,such as taking the zebra crossing,observing the traffic condition,running and playing with cellphones when walking across the road. Results: Totally 2 585 students were investigated,and 2 580 students were valid（99.81%）. When walking across the road,1 887 people took the zebra crossing,accounting for 73.14%;71.89% of boys and 74.51% of girls took the zebra crossing,and there was no significant difference（P>0.05）;64.76% and 81.32% of the students took the zebra crossing on the way to school and home,with a significant difference（P<0.05）. When walking across the road,1 683 students people observed the traffic conditions,accounting for 65.23%;63.61% of boys and 67.02% of girls observed the traffic conditions,and there was no significant difference（P>0.05）;64.05% and 66.39% of the students observed the traffic conditions on the way to school and home,with a significant difference（P<0.05）.There were 362 students running across the road, accounting for 14.03%;15.31% of boys and 12.62% of girls ran across the road,and there was no significant difference（P>0.05）;9.26% and 18.68% of the students ran across the road on the way to school and home,with a significant difference（P<0.05）. There were 53 students playing with cellphones when crossing the road,accounting for 2.05%;2.29% of boys and 1.79% of girls played with cellphones,and there was no significant difference（P>0.05）;1.41% and 2.68% of the students played with cellphones on the way to school and home,with a significant difference（P<0.05）. Conclusions Primary and secondary school students have dangerous behaviors when walking across the road. We should focus on the intervention of not taking the zebra crossing and not observing traffic conditions when crossing the road on the way to school,and playing with cellphones on the way home.

Objective: To learn the status of knowledge,attitude and behaviors of road traffic safety in primary and secondary school students in Xiacheng District of Hangzhou. Methods: The students of fourth to seventh grade from seven schools in Xiacheng District were selected and surveyed for their knowledge,attitude and behaviors of road traffic safety by self-designed questionnaires. Results: Totally 4 006（99.98%）students completed the survey,who mostly had awareness rates of over 90% in knowledge about safe behaviors when walking,walking across the road and riding a bicycle or an electric bicycle. The awareness rates of"should not run across the road","should not ride side by side"and"should not ride on the motorway"were relatively low,which were 81.65%,85.72% and 82.78%,respectively. About 68.47% of students thought it necessary to wear a helmet when riding a bicycle or an electric bicycle,72.22% of students thought it necessary to wear seatbelt or use child safety seat when taking a car. The two rates were significantly higher in girls than boys and in primary school students than secondary school students（P<0.05）. The top three unsafe behaviors the students did in the past six months were"not wear a helmet when riding a bicycle or an electric bicycle","run across the road"and"ride on the motorway",the rates of which were 86.84%,10.06% and 7.91%,respectively. Conclusion The knowledge of road traffic safety among primary and middle school students in Xiacheng District is mastered well. Interventions should be focused on unsafe behaviors including not wearing a helmet when cycling,riding on the motorway and running cross the road.

Objective To investigate the fluctuations in the population density of Aedes albopictus and changes in the population density of Ae. albopictus in different geographical areas and different breeding habitats in Guangdong Province from 2018 to 2023, so as to provide insights into prevention and control of mosquito-borne infectious diseases in the province. Methods Ae. albopictus surveillance sites were assigned in 1 609 townships (streets) from 121 districts (counties) of 21 cities in Guangdong Province during the period between March and November from 2018 to 2023. The surveillance of the population density of Ae. albopictus was performed once a month in each surveillance site, and once a month in specific settings in cities where dengue were highly prevalent in Guangdong Province from December to February of the next year during the period from 2018 through 2023. Four streets (villages) were selected in each surveillance site according to the geographic orientation, and mosquito ovitraps were assigned in gardens, rooftops or public green belts at residential areas, parks, hospitals and construction sites. All mosquito ovitraps were collected, and the mosquito ovitrap index (MOI) was calculated. The population density of Ae. albopictus was classified into four grades in each surveillance site according to MOI, including no risk, low risk, medium risk and high risk. The risk classification of the Ae. albopictus density was analyzed in each surveillance site each year from 2018 to 2023, and the population density of Ae. albopictus was analyzed at different months and in different geographical areas and breeding habitats. Results A total of 118 241 Ae. albopictus surveillance sites were assigned in 21 cities of Guangdong Province from 2018 to 2023, and there were 68.26% of the surveillance sites with the population density of Ae. albopictus that met the requirements for dengue prevention and control, among which low, medium and high risk surveillance sites accounted for 23.61%, 6.67% and 1.47%. The risk classification of the Ae. albopictus density increased rapidly in Guangdong Province since April to May each year from 2018 to 2023, and then gradually reduced since September to October, with the peak during the period between May and July. The mean MOI was 4.21 at each surveillance site in Guangdong Province during the period from 2018 to 2023, with 4.69, 4.80, 4.38, 3.82, 3.38, and 4.33 from 2018 to 2023, respectively. The MOI was 4.35, 4.43, 3.53 and 3.58 in the Pearl River Delta region, and eastern, western, and northern Guangdong Province, respectively, and was 4.18, 5.44, 4.75, 3.24, 4.27 and 3.70 in residential areas, parks, construction sites, hospitals, waste collection stations, and other breeding habitats, respectively. Conclusions The population density of adult Ae. albopictus peaked in Guangdong Province during the period between May and July from 2018 to 2023, with a high density of Ae. albopictus in the Pearl River Delta region and eastern Guangdong Province. Targeted Ae. albopictus control measures are recommended to be implemented prior to the peak of the Ae. albopictus population density to reduce the development of mosquito-borne infectious diseases.