Objective To explore the applicability of the Perceived Stress Scale(PSS) in Chinese medical students.Methods 773 medical students completed the PSS and the Depression Anxiety Stress Scale (DASS).The reliability and validity of the PSS were analyzed.Results The exploratory factor analysis showed that two factors were extracted from the scale,which could explain 53.74％ of the total variance.The confirmatory factor analysis verified that the structure of the PSS was two-dimensional (x2/df =2.863,CFI =0.943,TLI =0.924,GFI =0.951,AGFI =0.921,RMSEA =0.07).The internal consistency coefficient of the PSS,the perceived stress subscale and the perceived coping ability subscale were 0.858,0.852 and 0.750.The relationship between the PSS and the DASS was significant,which demonstrated that the PSS had a good criterion-related validity.In addition,t-test showed that girls had a higher level of the perceived stress than boys (t =-2.574,P =0.01),and students who lived in rural had a higher level of the perceived stress than students who lived in urban (t =2.788,P =0.005).Conclusion The study indicates that the PSS has a high level of the reliability and validity,and it is worthy of exploring the perceived stress in medical students.

Objective: To evaluate the correlation between electronic cigarette (e-cigarette) use and environmental e-cigarette exposure among residents living in Guangzhou City, so as to provide the evidence for the development of the e-cigarette control policy. Methods: Permanent university students living in Guangzhou City were recruited as investigators from July to October 2021, and the permanent adult residents in communities where the university students lived were randomly selected as participants. Subjects' demographic features, e-cigarette use, passive viewing of e-cigarette use and exposure to e-cigarette advertising were collected using both online and offline questionnaire surveys, and the association of e-cigarette use with passive viewing of e-cigarette use and exposure to e-cigarette advertising were examined using a multivariable logistic regression model. Results: A total of 948 questionnaires were allocated, and 874 valid questionnaires were recovered, with an effective recovery rate of 92.19%. The respondents had a mean age of ( 34.96±13.76 ) years. There were 420 men ( 48.05% ), and 426 married residents ( 48.80% ). The prevalence of e-cigarette use was 14.99%, and the rate of e-cigarette use was 23.81% in men and 6.83% in women. In addition, 27.27% of respondents at ages of 35 to 44 years used e-cigarette, 479 respondents viewed e-cigarette advertising ( 54.81% ) and 510 respondents had at least once passive viewing of e-cigarette use ( 58.35% ). Multivariable logistic regression analysis revealed that a higher frequency of exposure to e-cigarette advertising ( OR: 3.064-5.784, 95%CI: 1.683-12.620 ) and a higher frequency of passive viewing of e-cigarette use ( OR: 2.182-2.349, 95%CI: 1.094-4.526 ) led to a higher rate of e-cigarette use. Conclusions E-cigarette use is affected by passive viewing of e-cigarette use and exposure to e-cigarette advertising among community residents in Guangzhou City. Supervision and restriction is recommended for e-cigarette advertising, marketing, and use in public places.

Objective To investigate the effects of mirror visual feedback (MVF) and electromyographic biofeedback (EMGBF) on upper extremity function in hemiplegic patients after stroke based on task-oriented training. Methods 90 patients with hempiplegia after stroke were randomly divided into control group (n=30), EMGBF group (n=30) and MVF group (n=30). All patients accepted routine rehabilitation and task-oriented training once a day for 8 weeks. The EMGBF group also accepted EMGBF, and the MVF group accepted MVF in addition. They were assessed with Fugl-Meyer Assessment (FMA) and the Upper Extremity Function Test (UEFT), and their integrated electromyogram (iEMG) of affected upper extremities were recorded before and after treatment. Results All the groups improved in scores of FMA and UEFT, as well as the iEMG after treatment (P<0.05), and ranked as the MVF group, the EMGBF group and the control group from improving more to less (P<0.05). Conclusion Mirror visual feedback combined with electromyographic biofeedback may further promote the recovery of upper limb function in patients with hemiplegia after stroke based on task-oriented training.

As a metabolic disorder during pregnancy,gestational diabetes mellitus (GDM) has an important effects on fetal development,neonatal health and maternal long-term health,and is one of the pregnancy complications with high incidence.It is of great significance that we have an accurate understanding of the etiology and risk factors of GDM for its prevention and control.GDM is a complex disease with multiple etiologies.Current studies have shown that the occurrence of GDM may be the result of combined effect of heredity and environment,but the exact etiology is still unclear.In this paper,we summarized the possible etiologies and risk factors of GDM,so as to understand the occurrence and development of GDM better and to provide possible references for prevention and further etiological studies of GDM.

Mediation analysis is mainly used to explore the causal mechanism between independent variable X and dependent variable Y. It determines whether mediator M plays a role and evaluate the role’s degree in the causal path by decomposing the causal path between the independent variable X and the dependent variable Y. However, the classical mediation analysis is generally used for single mediator. This paper introduces a new mediation analysis method for multiple mediators.

At present, traditional methods on statistics have limitations in controlling time- varying confounding. This paper introduces an analysis method, parametric g-formula, which would adjust time-varying confounding, and also exemplifies the steps of its implementation for purpose to provide a new reference for researchers to deal with long-term observational data.