This social network study investigated the moderating role of self-control in the association between friendship and the development of externalizing behavior: Antisocial behavior, alcohol use, tobacco use. Previous studies have shown inconsistent findings, and did not control for possible friendship network or selection effects. We tested two complementary hypotheses: (1) That early-adolescents with low self-control develop externalizing behavior regardless of their friends’ behavior, or (2) as a result of being influenced by their friends’ externalizing behavior to a greater extent. Hypotheses were investigated using data from the SNARE (Social Network Analysis of Risk behavior in Early adolescence) study (N = 1144, 50 % boys, Mage 12.7, SD = 0.47). We controlled for selection effects and the network structure, using a data-analysis package called SIENA. The main findings indicate that personal low self-control and friends’ externalizing behaviors both predict early adolescents’ increasing externalizing behaviors, but they do so independently. Therefore, interventions should focus on all early adolescents’ with a lower self-control, rather than focus on those adolescents with a lower self-control who also have friends who engage in externalizing behavior.

Objectives: One explanation for the increase in delinquency in adolescence is that young people are trapped in the so-called maturity gap: the discrepancy between biological and social maturation, which motivates them to engage in delinquency as a temporary means to bridge this gap by emphasizing their maturity. In the current study, we investigated to what extent the discrepancy between pubertal status (i.e., biological maturation) and autonomy in decision making (i.e., social maturation) is related to conflict with parents, which in turn predicts increasing levels of delinquency as well as substance use. Methods: Hypotheses were tested by means of path models in a longitudinal sample of adolescent boys and girls (N = 1,844; M age 13.02) from the Social Network Analyses of Risk behaviors in Early adolescence (SNARE) study using a one-year time interval. Results: Results indicate that biological maturation in interaction with social maturation predict conflict with parents, which in turn was related to higher levels of delinquency and substance use over time. No gender differences were found. Conclusions: These findings reveal that conflict with parents is an important mechanism, linking the interplay of biological and social maturation with delinquency and substance use in early adolescence for boys and girls.

Magnetisable particles, coated with anti-salmonella serum, were used to isolate Salmonella livingstone from pure cultures, mixed cultures and food samples. Beads (10(7] were generally incubated with 10(4) Salm. livingstone cells/ml for 60 min at room temperature. The incubation and washing medium (0.01 mol/l phosphate-buffered saline; PBS) contained 0.1% bovine serum albumin (BSA) and 0.1% Tween 20, respectively. This method gave a recovery for Salm. livingstone of 51.0 +/- 7.8%. However, other micro-organisms such as Aeromonas hydrophila interfered with this test because of non-specific reactions (recovery 50.9 +/- 12.7%). These non-specific reactions could be decreased by using 4% skim milk instead of 0.1% BSA in the incubation medium. The ratio of the recovery of Salm. livingstone relative to the recovery of Aer. hydrophila changed from 0.9 when PBS with 0.1% BSA was used, to 13.4 when PBS with 4% skim milk was used. Immunomagnetic separation of Salmonella spp. from food samples offers good prospects for concentrating salmonella cells from heterogeneous bacterial suspensions, such as enrichment broths.

This study examined friendship (de-)selection processes in early adolescence. Pubertal development was examined as a potential moderator. It was expected that pubertal development would be associated with an increased tendency for adolescents to select their friends based on their similarities in externalizing behavior engagement (i.e., delinquency, alcohol use, and tobacco use). Data were used from the first three waves of the SNARE (Social Network Analysis of Risk behavior in Early adolescence) study (N = 1144; 50 % boys; M age = 12.7; SD = 0.47), including students who entered the first year of secondary school. The hypothesis was tested using Stochastic Actor-Based Modeling in SIENA. While taking the network structure into account, and controlling for peer influence effects, the results supported this hypothesis. Early adolescents with higher pubertal development were as likely as their peers to select friends based on similarity in externalizing behavior and especially likely to remain friends with peers who had a similar level of externalizing behavior, and thus break friendship ties with dissimilar friends in this respect. As early adolescents are actively engaged in reorganizing their social context, adolescents with a higher pubertal development are especially likely to lose friendships with peers who do not engage in externalizing behavior, thus losing an important source of adaptive social control (i.e., friends who do not engage in externalizing behavior).Electronic supplementary materialThe online version of this article (doi:10.1007/s10802-016-0134-z) contains supplementary material, which is available to authorized users.

This study investigated the social status (i.e., popularity, likeability, and friendships) of adolescents with an early onset of externalizing behavior (i.e., alcohol use, tobacco use, and antisocial behavior). Building on Moffitt's dual-taxonomy model, it was hypothesized that early onset adolescents were more popular, but not necessarily more liked or with more friends. Hypotheses were tested using data from the Social Network Analysis of Risk Behaviors in Early Adolescence (SNARE) study (N = 1,100, 50% boys, X age = 12.7, SD = 0.47 years). Findings indicated that adolescents with an early onset of one or more externalizing behaviors were more popular, less liked, and had as many friends as their peers. These findings suggest that early onset adolescents potentially function as role models.