Objective: To explore the influence of social support and school connectedness on the developmental trajectory of self efficacy in adolescents and analyze its subgroup effects, so as to provide a basis for enhancing adolescents self-efficacy. Methods: Using a cluster random sampling method, 930 first year middle school students from four schools in Xiangxi Autonomous Prefecture, Hunan Province, were selected for three longitudinal surveys in October 2023 (T1), April 2024 (T2), and October 2024 (T3). The General Self-efficacy Scale (GSES), Social Support Scale (SSS), and School Connectedness Scale (SCS) were administered. Latent growth mixture modeling (LGMM) was used to identify different developmental trajectories of self-efficacy in early adolescence. Multivariate Logistic regression was employed to examine the associations of self-efficacy trajectories with social support and school connectedness in adolescents. Results: The developmental trajectory of self-efficacy in adolescents was classified into three categories:category 1 was low efficacy-rapid growth group (53 students, 6.6%), category 2 was moderate efficacy-stable growth group (793 students, 84.1%), and category 3 was high efficacy-rapid decline group (84 students, 9.3%). Using the low efficacy- rapid growth group as the reference, students with higher social support were more likely to belong to the moderate efficacy- stable growth group ( OR=1.06, 95%CI =1.03-1.08) and the high efficacy-rapid decline group ( OR=1.06, 95%CI = 1.03 -1.09), students with higher school connectedness were more likely to belong to the high efficacy-rapid decline group ( OR= 1.10 , 95%CI =1.03-1.18) (all P <0.05). Subgroup analysis revealed significant effects for boarding status (low efficacy-rapid growth group at T1, t =2.10; high efficacy-rapid decline group in social support, t =-2.15) and only child status (moderate efficacy-stable growth group at T2, t =2.05) (all P <0.05). Conclusions The developmental trajectory of self-efficacy in adolescents exhibits group heterogeneity, with boarding status and only child status showing subgroup effects. Enhancing social support and school connectedness can help improve self-efficacy in adolescents.

Objective: To explore the association of latent profiles of mobile phone dependence and self control with physical exercise among junior high school students, so as to provide references for the prevention of mobile phone dependence and the improvement of self control among junior high school students. Methods: From April to May 2024, a stratified random cluster sampling method was used to select a total of 2 311 students from grade 7 to grade 9 in three public junior high schools in Xiangxi Autonomous Prefecture, Hunan Province. Latent profile analysis was conducted to identify the latent profiles of mobile phone dependence and self control among junior high school students. Pearson correlation analysis was used to examine the correlation between mobile phone dependence and self control, and Chi square test was used to analyze the distribution differences of latent profiles of adolescents across different demographic characteristics. Multiple Logistic regression analysis was applied to explore the association between mobile phone dependence, self control, and physical exercise. Results: Four latent profiles of mobile phone dependence and self control were identified: low dependence-moderate self control group ( n =885, 38.3%), moderate dependence-low self control group ( n =910, 39.4%), high dependence-no self control group ( n =232, 10.0%), and no dependence-high self control group ( n =284, 12.3%). Significant differences were observed in the distribution of latent profiles across gender, grade and only child status ( χ 2=10.85, 35.72, 13.85， P <0.05). Logistic regression analysis showed that, after controlling for demographic variables, compared with the low dependence-moderate self control group, physical exercise was negatively associated with the moderate dependence-low self control group ( OR =0.79) and the high dependence-no self control group ( OR =0.81), while positively associated with the no dependence-high self control group ( OR =1.58) ( P <0.01). Conclusions The influence of physical exercise on junior high school students different potential profile types of mobile phone dependence and self control is different. Schools and families should adopt targeted physical exercise interventions based on the characteristics of different profiles to promote the physical and mental health of junior high school students.

Objective: To analyze the heterogeneity of mobile phone dependence development trajectory in middle school students and its association with loneliness and selfcontrol ability, so as to provide reference for the prevention of mobile phone dependence in middle school students. Methods: A total of 941 grade 1 students from 4 public middle schools in Xiangxi Autonomous Prefecture, Hunan Province were selected for the followup survey by random cluster sampling from October 2023 to April 2024 and October 2024. Mobile Phone Addiction Index (MPAI), University of California, Los Angeles Loneliness Scale-20 (UCLA-20) and Selfcontrol Scales (SCS) were used for questionnaire survey. The heterogeneity of the developmental trajectory of middle school students mobile phone dependence was analyzed by the latent growth curve model (LGMM), and the influencing factors of the developmental trajectory of middle school students mobile phone dependence were explored by multiple Logistic regression analysis. Results: The development trajectory of middle school students mobile phone dependence could be divided into four categories: C1 "low risk slow decline group (n=438,44.6%)", C2 "medium risk slow rise group (n=272,29.7%)", C3 "high risk rapid decline group (n=73,8.6%)" and C4 "high risk rapid rise group (n=158,17.1%)". There were significant differences in the distribution of mobile phone dependence development track heterogeneity subgroups among sex, only child, lodging, and leftbehind students (χ2=117.79, 44.88, 37.09, 130.50, P <0.01). The results of the multinomial Logistic regression model analysis showed that, with C1 group as the reference, C2, C3, and C4 were positively correlated with students loneliness [OR(95%CI)=1.04 (1.02-1.06), 1.11(1.08-1.14), 1.12(1.09-1.14)]; C2 and C4 groups were negatively correlated with students selfcontrol [OR(95%CI)=0.97(0.96-0.99), 0.95(0.93-0.97)] (P<0.01). Conclusions The development trajectory of mobile phone dependence among middle school students is heterogeneous. Reducing the loneliness of individuals and cultivating good selfcontrol ability are helpful to alleviate mobile phone dependence behavior among middle school students.