Effect of aggregations of aphids ( Periphyllus spp.) on their size

In autumn, aphids reared on the opposite side of a sycamore leaf from an aggregation ofPeriphyllus acericola nymphs are heavier than aphids reared on uninfested leaves. Groups ofP. testudinaceus nymphs do not enhance the growth of aphids reared opposite.

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Zusammenfassung H?lt man einzelne Blattl?use (Drepanosiphum platanoidis oderPeriphyllus acericola) auf einem Bergahornblatt, das auf der Gegenseite mit einer Aggregation vonPeriphyllus acericola befallen ist, so werden sie etwa um das doppelte schwerer. Dieser Effekt zeigte sich nicht bei Gruppen vonP. testudinaceus.

     

Communication with Best Friends About Sex-Related Topics During Emerging Adulthood

During emerging adulthood, relationships with close friends may be particularly important and influential, yet most research on communication about sex-related topics focuses on emerging adults' communication with parents. Two hundred and five college students (61% female, mean age = 20.5) completed surveys about the frequency and quality of their sex-related conversations with same-sex best friends, and their sexual attitudes and behaviors. These conversations were more frequent between females, and between less religious youth. Sexually active youth discussed most topics more frequently than abstinent youth, although abstinent youth discussed abstinence more frequently. More frequent and comfortable conversations were generally associated with more liberal sexual attitudes, and more positive condom-related attitudes. Differential associations between the specific topics discussed and attitudes about sexuality, HIV, and condoms highlight the importance of examining multiple dimensions of sex-related communication rather than the unidimensional measures typically employed.     

Does Body Image Play a Role in Risky Sexual Behavior and Attitudes?

Body image and sexuality, both physically-oriented domains of the self, are likely linked, but few studies have examined their associations. In the present investigation, we studied emerging adult undergraduates (ages 17–19), focusing specifically on risky sexual behaviors and attitudes. Participants (N=434) completed a survey on body image, lifetime sexual behavior, sexual double standard attitudes, and attitudes about condoms. Males who evaluated their appearance more positively and who were more oriented toward their appearance were more likely to report risky sexual behavior, yet females who evaluated their appearance more positively were less likely to report risky sexual behavior. For most sexual attitudes, patterns did not differ by gender. Individuals who were more oriented toward their appearance believed more in the sexual double standard, and those who had more positive evaluations of their appearance perceived fewer barriers to using condoms. Intervention implications are discussed.An earlier version of this paper was presented at the 2003 Emerging Adulthood Conference, Boston, MA.Doctoral candidate in the Department of Human Development and Family Studies at the Pennsylvania State University. Her research interests include body image, sexuality, and gender in adolescence and emerging adulthood.Associate Professor in the Department of Human Development and Family Studies at the Pennsylvania State University. She received her PhD in developmental psychology from the University of California, Los Angeles. Her research interests include sexuality, interpersonal relationships, and gender role development during adolescence and emerging adulthood.Doctoral candidate in the Department of Human Development and Family Studies at the Pennsylvania State University. Her research interests include gender, adolescent development, and family relationships     

Sexual dimorphism in human browridge volume measured from 3D models of dry crania: A new digital morphometrics approach

Sex estimation from the human skull is often a necessary step when constructing a biological profile from unidentified human remains. Traditional methods for determining the sex of a skull require observers to rank the expression of sexually dimorphic skeletal traits by subjectively assessing their qualitative differences. One of these traits is the prominence of the glabellar region above the browridge. In this paper, the volume of the browridge region was measured from digital 3D models of 128 dry crania (65 female, 63 male). The 3D models were created with a desktop laser scanner, and the browridge region of each 3D model was isolated using geometric planes defined by cranial landmarks. Statistical analysis of browridge-to-cranium volume ratios revealed significant differences between male and female crania. Differences were also observed between geographically distinct populations, and between temporally distinct populations from the same locale. The results suggest that in the future, sex determination of human crania may be assisted by quantitative computer-based volume calculations from 3D models, which can provide increased objectivity and repeatability when compared to traditional forensic techniques. The method presented in this paper can easily be extended to other volumetric regions of the human cranium.