Objective To understand the relationship of anxiety and depression with social behav?ior of young men who have sex with men（YMSM）.Methods A snowball sampling method was used to re?cruit YMSM aged 15-24 years in Mianyang City，Sichuan Province，to perform social behavior investiga?tion and serological testing. Self?rating anxiety scale（SAS）and self?rating depression scale（SDS）were ap?plied to measure anxiety and depression symptoms. Anxiety and depression symptoms and social behavior were analyzed with univariate analysis by Chi?square test and multivariate analysis by unconditional logis?tic regression. Results A total of 356 and 355 YMSM were separately determined by SAS and SDS，with a median age of 21 years. Of all the participants，62.08% had educational level of college or above， 68.54% were students or office clerks，and 55.06% had household registers in Mianyang. Total average score of SAS and SDS standard score were（42.96 ± 10.81）and（45.63 ± 12.40），and the detection rates of anxiety and depression symptoms were 23.60% and 33.24%，respectively. There was no significant dif?ference in the positive rate of HIV infection between groups with and without anxiety and depression symp?toms（P＞0.05），but the significant difference in syphilis infection rates was observed between groups with and without depression symptoms（P＜0.05）. Multivariate logistic regression showed that compared with insertive YMSM，the MSM with both receptive and insertive anal sex were more likely to detect anxi?ety（OR＝3.524）；suicidal thought and sexual abuse experience were the promoting factors of anxiety symptoms（OR＝2.782，14.013）；open sexual orientation was a protective factor（OR＝0.222）；the MSM with both receptive and insertive anal sex were more likely than insertive MSM and receptive MSM to have depression（OR＝3.916，2.309）；negative attitude of sex orientation and experience of sexual abuse were the promoting factors of depression symptoms（OR＝4.770，7.186）. Conclusion YMSM in Mianyang had high detection rates of anxiety and depression symptoms and poor mental health. Anxiety and depres?sive symptoms were associated with social behavior，and psychological intervention should be carried out.

Objective To analyze the impact of ambient PM2.5 on hospital outpatient visits for respi?ratory diseases. Methods Data on ambient PM2.5，PM10，SO2，NO2，CO，O3-1h and O3-8h in 2017 were collected from Foshan Meteorological Bureau and Foshan Environmental Protection Bureau. Data on daily hospital outpatient visits were collected from two hospitals in Foshan. A time?series analysis using a gener?alized additive model（GAM）was applied to assess the association between ambient PM2.5 concentration and hospital outpatient visits for respiratory diseases after adjustment for long ?term trend，day ?of ?week， meteorological factors and other air pollutants. Results Air pollution in Foshan City showed excellent lev?el as a whole in 2017. The main pollutants of PM2.5，PM10，SO2，NO2，CO，O3-1h，and O3-8h met the sec?ond or higher standards of the National Environmental Air Quality Standard（GB 3095-2012）. The aver?age PM2.5 concentration in Foshan in 2017 was 33.2 μg/ m3，meeting the national second ?level standard. The numbers of days exceeding the standard were 9 days all the year round. The total outpatient visits for respiratory diseases in the two hospitals were 261 158 with average 715.50 visits per day. The hospital dai?ly average outpatient visits for respiratory diseases were positively correlated with the air pollutants of SO2， NO2，and PM10 by the Spearman correlation analysis（R：0.19，0.33，0.20；P＜0.05 for all）. The GAM analysis showed that the daily average concentration of ambient PM2.5 was positively correlated with the hos?pital outpatient visits for respiratory diseases. The effect of ambient PM2.5 was the largest on lag 0 day（ER＝2.744；95% CI：0.701，4.827）. For every 10 μg/m3 increment of ambient PM2.5，the daily outpatient vis?its for respiratory diseases increased by 2.744%。 In the analysis of multi-pollutant model，when introduc?ing O3-1h（ER＝3.425；95% CI：1.278，5.617）and O3-8h（ER＝4.611；95% CI：2.373，6.899），their combined effect with PM2.5 made the correlation between PM2.5 and outpatient visits for respiratory diseases increased significantly. Conclusion The ambient PM2.5 concentration was positively associated with hospi?tal outpatient visits for respiratory diseases in Foshan City.

Objective To understand the status of quality of life（QOL），social support and in?fluencing factors of the compulsory drug abstainers，so as to provide scientific basis for improving their QOL treatment and education in Zhanjiang City. Methods A questionnaire survey was carried out by us?ing self ?compiled general information questionnaire，understanding social support scale and the World Health Organization Quality of Life（WHOQOL?BREF）to investigate drug addicts in a compulsory isola?tion detoxification center in Zhanjiang City. Data were analyzed by Student’s t?test，variance analysis and Pearson correlation analysis. Results A total of 488 male compulsory drug abstainers were investigated， with an average age of（39.32 ± 7.90）years. Of the subjects，47.75%（233/488）had stayed in the center for 6 to 12 months. The total score of perceived social support（52.12 ± 13.52），family support score（18.02 ± 5.45）and other support score（17.01 ± 4.91）of the compulsory drug abstainers were higher than those of domestic norm（all P＜0.01），but the scores of friend support（17.09 ± 5.07），physiological do?main（54.53 ± 15.09），psychological domain（53.20 ± 16.13），social relationship（55.67 ± 18.94）andenvironmental domain（49.14 ± 17.07）were less than those of the domestic norm（all P＜ 0.01）. The low?er the age of the respondents was，the higher the scores in the psychological and environmental domains would be；the higher the level of education was，the higher the scores in the physical，psychological，and environmental domains，perceived social support，family support，friend support，and other support would be；married subjects had higher scores of social relations and family support than those in unstable marriages；the respondents with jobs had higher scores of social relation and environmental domains than those without jobs；the higher the income was，the higher the scores of the physical，psychological，social relationship and environmental domains，and the perceived social support and family support would be； the longer the time in the compulsory detoxification was，the higher the scores of psychological，environ?mental，and other support would be（P＜0.05 for all）. Conclusion The QOL and perceived social sup?port level of compulsory drug abstainers were relatively low in Zhanjiang City. It is suggested that the gov?ernment，society and families should improve the social support for drug abstainers.

Objective To investigate epidemiological characteristics and factors influencing non ?suicidal self?injury（NSSI）behaviors among middle school students in Shenzhen and to provide scientific evidence for its intervention and prevention. Methods A stratified cluster sampling method was used to select middle school students from 10 schools in Shenzhen for questionnaire survey. The survey content in?cluded general conditions and injury behavior. A Chi?square test and logistic regression were used for data analysis. Results A total of 3 737 students，including 2 033 boys and 1 704 girls，were surveyed，and the ratio of males to females was 1.19∶1. The average age of the participants was 15 years old. In the past year，the prevalence rate of NSSI among middle school students in Shenzhen was 34.7%. Unconditional multivariate logistic analysis showed that the NSSI level of students aged 11-16 years was higher than that of the other age groups（OR＝1.220），the students with trauma had higher NSSI level than those without trauma（OR＝1.788），the NSSI level of students living on campus was lower than that of students not liv?ing on campus（OR＝0.724），and the incidence of NSSI among students with close friends was lower（OR＝0.804）. Conclusion s The prevalence rate of NSSI among middle school students in Shenzhen was high. Early detection of NSSI and interventions based on relevant influencing factors should be taken to re?duce and prevent the occurrence of NSSI.

Objective To determine appropriate reference ranges for evaluating local fetal head circumference（HC）. Methods HC measurements of fetuses who accepted ultrasound detection from Sep?tember 2012 to December 2016 in our hospital were collected. Kappa value and Youden index were used to compare the consistency between the reference ranges and the actual data，and evaluate the sensitivity and specificity. Results Data on HC of singleton fetuses at 13-40 gestational weeks were collected. The aver?age age of the pregnant women was 29 years. The proportions of male and female fetuses were 53.1% and 46.9%，respectively，and 97.5% of the fetuses were from Guangdong. The Kappa value and Youden index of the Chinese national reference ranges were 0.86 and 0.97 respectively，higher than those of the other four reference ranges. But the Youden index was on the low side at 23，28，and 40 gestational weeks.In 18 to 28 weeks，the reference ranges of fetal development in white population was doser to the actual detection value. Conclusion s The Chinese national reference ranges of fetal HC are highly consistent with local fetal HC，but not suitable for all gestational weeks. It was recommended to update the reference ranges for Guangdong fetuses.

Objective To explore the breast self?examination（BSE）behavior and associated fac?tors among female college students，so as to provide reference for improving their prevention of breast can?cer and the awareness of breast health care. Methods Questionnaire survey was conducted among female college students in Suzhou City. The survey included the basic conditions of the participants，BSE，and health belief mode（l HBM）. The BSE of respondents was described and analyzed. Univariate and multivari?ate logistic regressions were used to analyze the influencing factors. Results A total of 1 098 female col?lege students in 5 colleges and universities in Suzhou were surveyed，with an average age of（19.90 ± 1.04）years. Of the participants，45.6% were in the first year at the university and 46.2% the second year； 98.9% were the Han nationality，60.3% specialized in the medical science，and 68.5% were from northern Jiangsu（in the north region of the Yangtze River within Jiangsu Province）. The HBM scores related to breast cancer screening，ranking from highest to lowest，were perceived severity，perceived benefit，per?ceived susceptibility，self ?efficacy，and perceived impairment. The scores of knowledge and risk factors for breast cancer were（3.52 ± 0.41）and（4.78 ± 2.27），respectively. Among the respondents，30.1%（330/1 098）had practiced BSE，and 8.8%（90/1 098）practiced monthly. Multivariate logistic regression showed that female students with higher scores of perceived susceptibility（OR＝1.188），self?efficacy（OR＝1.598），breast cancer knowledge derived from health care practitioners（OR＝1.754），female friends（OR＝1.898），and history of breast cancer among immediate family members（OR＝4.205）were more like?ly to practice BSE. Conclusion The BSE rate of female college students was low. Health education should be effectively carried out and breast cancer knowledge should be popularized to improve perceptual susceptibility，self?efficacy，breast cancer prevention consciousness and BSE rate.