CONTEXT Early age at first sex has been identified as a risk factor for unplanned pregnancy and HIV infection. However, the emotional relationships and physical behaviors that precede first intercourse, and how they differ by sex, also may provide important cues about how to prevent sexual risk behavior. METHODS The precoital activities of 2,051 adolescents aged 17-19 in Cebu, Philippines, ar...

CONTEXT Despite high levels of sexual activity and risk behaviors among Jamaican youth, few population-based studies have examined their prevalence or correlates. METHODS The prevalence of three sexual risk behaviors was assessed using data from the 2008-2009 Jamaican ?Reproductive Health Survey on a subsample of adolescents aged 15-19 who neither were in a union nor had a child. Factors asso...

animals that can estimate their desirable habitat quality are better able to accordingly adapt their life behaviors. the life cycles of parasitoids are so closely adapted as to match their hosts life behavior. among the various host-parasitoid interactions, a peculiarity is the seasonal synchrony between host and parasitoid activity. the foraging and oviposition behaviors of lysiphlebus fabarum...

Gonadal steroid hormones influence an animal's sexual behavior through two primary means. During development they affect differentiation of the brain (primarily in males), and after puberty, circulating concentrations of steroids influence expression of sexual behaviors. In mammals, sexual behaviors of females are regarded as inherent (independent of steroids secreted by the developing ovary). ...

Non-competitive and non-threatening aspects of social hierarchy, such as politeness, are universal among human cultures, and might have evolved from ritualized submission in primates; however, these behaviors have rarely been studied. Honorific language is a type of polite linguistic communication that plays an important role in human social interactions ranging from everyday conversation to in...

It is known that plant viruses can change the performance of their vectors. However, there have been no reports on whether or how a semipersistent plant virus manipulates the feeding behaviors of its whitefly vectors. Cucurbit chlorotic yellows virus (CCYV) (genus Crinivirus, family Closteroviridae) is an emergent plant virus in many Asian countries and is transmitted specifically by B and Q bi...

The ability of an animal to respond with appropriate defensive behaviors when confronted with an immediate threat can affect its survival and reproductive success. In the roughskin newt (Taricha granulosa), exogenous corticosterone (CORT) rapidly blocks and vasotocin (VT) enhances reproductive behaviors (mainly clasping behavior). Electrophysiological studies have shown that pretreatment of mal...

Homosexual adolescents may face significant health disparities. We examined health-risk behaviors and health cognition related to homosexual behavior in a representative sample of adolescents.Data were obtained from 129,900 adolescents between 2008 and 2012 over 5 cycles of the Korean Youth Risk Behavior Survey, a national survey of students in grades 7 to 12. Various health-risk behaviors and ...

This study estimated the length-weight relationship, sex ratio and population parameters of mantis shrimp, Harpiosquilla harpax from the coastal waters of Pantai Remis, Perak, Malaysia between February 2012 and October 2012. Total length and weight of 804 specimens of H. harpax were measured and the sex ratio was 1: 0.83 (M: F). Males of H. harpax were dominant over the females throughout the s...