Competence and self-esteem during transition from childhood to adolescence.

Change and stability in competence and self-esteem of fifth- and sixth-grade boys and girls were examined across a 1-year period, in which approximately one half of the children made the transition from elementary to secondary school (transition groups) and the other half continued in the same school (nontransition groups). Beginning at the end of the school year before transition, the Perceived Competence Scale for Children and the Teacher's Rating Scale of Child's Actual Competence were administered at 6-mo intervals. There was no notable transition effect either early or late in the new school year. Overall, children's perceived competence increased and was stable across the 1-year period. Teacher ratings also reflected competence gains for children in nontransition groups; but for children in transition groups they were substantially lower in secondary than in elementary school. The results indicate that entry into secondary school represents significant change from elementary school, but that most children negotiate the transition without undue difficulty. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Perceptions of puberty: Adolescent, parent, and health care personnel.

This study was designed (a) to examine relations among ratings of pubertal stage by adolescents, parents, and health care personnel, and (b) to determine if accuracy of adolescent and parent ratings varied with stage of puberty. Ss were 90 healthy adolescents: 46 boys, ages 10–15, and 44 girls, ages 9–15, and their parents. Ss were shown photos of the 5 stages of puberty (Tanner criteria). Ss rated the adolescents" pubertal stage, and a nurse practioner completed an examination to rate the adolescents" stage. Correlations between adolescent and examiner ratings ranged from r?=?.77 to r?=?.91 (p?≤?.001, κ?=?.33 to .50), and between parent and examiner from r?=?.75 to r?=?.87 (p?≤?.001, κ?=?.13 to .55). When inaccurate, Ss ratings were lower than examiner ratings and less accurate at later stages of puberty. Use of adolescent and parent ratings is limited if precise ratings of stage are necessary to answer a research question. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Swelling and Rheological Studies of Some Starch Hydrogels

Hydrogels with moderate water retention capacity and salt stability have been prepared from starch, oxidized starch, and amylopectin all crosslinked with epichlorohydrin. The swelling power was measured in water and in various salt solutions of different concentrations. The swelling capacity decreases with increasing both the crosslinker and the polymer concentration. The plateau modulus (G′_p) of the prepared gels was determined from complex dynamic viscosity measurements. G′_p was measured as a function of the epichlorohydrin and polymer concentrations. The loss modulus (G″) for the prepared gels was also measured and was always found to be almost zero. The molecular weight between two entanglement points (mesh width) was estimated from the G′_p values. The ratio between the number of elastically effective entanglement points, calculated from the G′_p values, and that calculated from complete conversion of the cross-linker was also estimated for various gels. It was found that this ratio is very small (0.2–0.7%) for gels prepared with 10 wt-% starch, it increases however to 13% at higher starch concentration of 25 wt-%.     

Relations between hormone levels and observational measures of aggressive behavior of young adolescents in family interactions.

Relations between hormone levels and aggressive behavior of adolescents in family interactions were examined in 30 boys and 30 girls, 9 to 14 years of age. The adolescents represented all five stages of pubertal development (Tanner criteria). Circulating levels of gonadotropins (luteinizing hormone and follicle-stimulating hormone), gonadal steroids (testosterone and estradiol), adrenal androgens (dehydroepiandrosterone, dehydroepiandrosterone sulphate, and androstenedione), and testosterone-estradiol binding globulin were assessed. These hormones are responsible for growth and sexual development during puberty and correlate with Tanner stage. The behavioral measures described the adolescents' expressions of anger and attempts to control or defy their parents and were based on videotaped family interactions during problem-solving tasks. On the basis of multiple regression analyses, higher estradiol and androstenedione levels were associated with higher degrees of aggressive behaviors for girls. Findings were sparse for boys. Findings are discussed in terms of (a) effects of degree of stability of hormone levels on detection of hormone-behavior relations, (b) organizing and activating influences of hormones on behavior, and (c) other mechanisms possibly underlying the relations. (PsycINFO Database Record (c) 2010 APA, all rights reserved)