Relationship between Levels of Testosterone and Cortisol in Saliva and Aggressive Behaviors of Adolescents

Objective To explore the endocfinal factors which influence the aggressive behavior of adolescents. Methods The levels of cortisol （CORT）, testosterone （T）, prolactin （PRL）, and growth hormone （GH） in saliva from 20 aggressive students and 20 non-aggressive control students were measured by radioimmunoassay （RIA）. The students were matched for their gender, age, grade, stage of pubertal development, and economic status of their families. Results The salivary T levels were 22.20±14.50 pg/mL and 19.54±12.52 pg/mL in aggressive male and female students, 13.20±6.85 pg/mL and 5.24±3.03 pg/mL in non-aggressive male and female students （P〈0.05）. The male aggressive students had a lower level of CORT in saliva than non-aggressive male students （P〈0.05）. There were no significant differences in the salivary levels of PRL or GH between the aggressive and non-aggressive groups. Correlation analysis revealed a negative relationship in male students between the salivary CORT levels and the aggression factor scores of the child behavior checklist （CBCL）. In addition, the data also showed a positive relationship between the salivary T levels and the aggression factor scores of CBCL in female students. Multiple linear regression analysis showed that the salivary CORT level was an independent predictive factor for aggressive behaviors in adolescent boys. The higher the CORT level, the less aggressive the boys were. Conclusion CORT and T levels may play a certain role in adolescent aggressive behaviors.

Synchronization of coupled metronomes on two layers

Coupled metronomes serve as a paradigmatic model for exploring the collective behaviors of com- plex dynamical systems, as well as a classical setup for classroom demonstrations of synchronization phenomena. Whereas previous studies of metronome synchronization have been concentrating on symmetric coupling schemes, here we consider the asymmetric case by adopting the scheme of layered metronomes. Specifically, we place two metronomes on each layer, and couple two layers by placing one on top of the other. By varying the initial conditions of the metronomes and adjusting the friction between the two layers, a variety of synchronous patterns are observed in experiment, including the splay synchronization （SS） state, the generalized splay synchronization （GSS） state, the anti-phase synchronization （APS） state, the in-phase delay synchronization （IPDS） state, and the in-phase syn- chronization （IPS） state. In particular, the IPDS state, in which the metronomes on each layer are synchronized in phase but are of a constant phase delay to metronomes on the other layer, is observed for the first time. In addition, a new technique based on audio signals is proposed for pattern detection, which is more convenient and easier to apply than the existing acquisition techniques. Furthermore, a theoretical model is developed to explain the experimental observations, and is employed to explore the dynamical properties of the patterns, including the basin distributions and the pattern transitions. Our study sheds new lights on the collective behaviors of coupled metronomes, and the developed setup can be used in the classroom for demonstration purposes.

Cluster synchronization in complex network of coupled chaotic circuits： An experimental study

By a small-size complex network of coupled chaotic Hindmarsh-Rose circuits, we study experimen- tally the stability of network synchronization to the removal of shortcut links. It is shown that the removal of a single shortcut link may destroy either completely or partially the network synchroniza- tion. Interestingly, when the network is partially desynchronized, it is found that the oscillators can be organized into different groups, with oscillators within each group being highly synchronized but are not for oscillators from different groups, showing the intriguing phenomenon of cluster synchro- nization. The experimental results are analyzed by the method of eigenvalue analysis, which implies that the formation of cluster synchronization is crucially dependent on the network symmetries. Our study demonstrates the observability of cluster synchronization in realistic systems, and indicates the feasibility of controlling network synchronization by adjusting network topology.