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91.
Evaluation of Commercial Kits for Dual Extraction of DNA and RNA from Human Body Fluids, ,
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Andrew J. Schweighardt Ph.D. Courtney M. Tate Ph.D. Kristina A. Scott M.S. Kathryn A. Harper M.S. James M. Robertson Ph.D. 《Journal of forensic sciences》2015,60(1):157-165
STR typing of DNA evidence can identify the donor with a high power of discrimination but cannot identify the tissue origin of a body‐fluid stain. Using RNA to attribute a crime scene stain to a particular tissue may aid in reconstruction efforts. With blood from 10 donors, four DNA and RNA coextraction kits were evaluated by measuring yields and STR and mRNA profiles. T tests indicated some significant differences in kit performance. The Zymo Research ZR‐Duet? kit performed best based on average DNA (41.4 ng) and mRNA (4.07 ng) yields and was the only kit to provide complete DNA/RNA profiles for all samples. The consistency of this kit was challenged by data from additional blood and saliva donors. Further testing is advised before a superior kit is unequivocally chosen. Stand‐alone DNA or RNA purification generally offers higher yield, but coextraction may still allow successful STR profiling and tissue source identification. 相似文献
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Natalie Kretsch Jane Mendle Jessica Duncan Cance Kathryn Paige Harden 《Journal of youth and adolescence》2016,45(8):1696-1710
Self-report measures of perceived pubertal timing correspond only weakly with clinical measures of “objective” physical development. Peer and school contexts shape adolescents’ self-perceptions of pubertal timing. The current study examined associations between perceived pubertal timing and the pubertal timing reported by nominated friends and schoolmates. Participants included 2817 adolescents (Mage = 16.6; 49 % female; 16 % Black; 20 % Hispanic) from the National Longitudinal Study of Adolescent Health. Three measures of pubertal timing were included: age-standardized ratings of body changes, comparisons of development relative to peers (relative timing), and, in females, age at menarche. It was hypothesized that relative timing, which explicitly asks adolescents to compare themselves to their peers, would be related to the age-standardized pubertal timing of nominated friends and schoolmates. Surprisingly, there were no associations between relative timing and age-standardized pubertal timing reported by peers, suggesting that pubertal self-perceptions do not fluctuate in response to the average level of development in a friend group. Instead, males were similar to nominated friends and schoolmates in age-standardized ratings of body changes, and females were similar to nominated friends in relative timing, controlling for race, ethnicity, and age. Different self-report measures of pubertal timing index different underlying constructs, and the social processes that influence adolescents’ perceptions of pubertal maturation may differ between genders. 相似文献
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Kathryn L. Modecki Bonnie L. Barber Lynnette Vernon 《Journal of youth and adolescence》2013,42(5):651-661
Technologically mediated contexts are social arenas in which adolescents can be both perpetrators and victims of aggression. Yet, there remains little understanding of the developmental etiology of cyber aggression, itself, as experienced by either perpetrators or victims. The current study examines 3-year latent within-person trajectories of known correlates of cyber-aggression: problem behavior, (low) self-esteem, and depressed mood, in a large and diverse sample of youth (N = 1,364; 54.6 % female; 12–14 years old at T1). Findings demonstrate that developmental increases in problem behavior across grades 8–10 predict both cyber-perpetration and victimization in grade 11. Developmental decreases in self-esteem also predicted both grade 11 perpetration and victimization. Finally, early depressed mood predicted both perpetration and victimization later on, regardless of developmental change in depressed mood in the interim. Our results reveal a clear link between risky developmental trajectories across the early high school years and later cyber-aggression and imply that mitigating trajectories of risk early on may lead to decreases in cyber-aggression at a later date. 相似文献
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Kaylin M. Greene Bora Lee Nicole Constance Kathryn Hynes 《Journal of youth and adolescence》2013,42(10):1557-1572
Prior research suggests that youths’ engagement in out-of-school time programs may be a crucial factor linking program participation to positive outcomes during adolescence. Guided by the theoretical concept of flow and by stage-environment fit theory, the present study explored correlates of engagement in youth programs. Engagement was conceptualized as the extent to which youth found the program activities enjoyable, interesting, and challenging. The current study examined how program content, monetary incentives, and youth demographic characteristics were linked to youth engagement among a sample of primarily low-income middle and high school youth attending 30 out-of-school programs (n = 435, 51 % female). Results from multilevel models suggested that program content and staff quality were strongly associated with youth engagement. Youth who reported learning new skills, learning about college, and learning about jobs through activities in the program were more engaged, as were youth who found the staff caring and competent. Results demonstrated that the link between learning content for the future and engagement was stronger for older youth than younger youth. In addition, there was a trend suggesting that providing a monetary incentive was associated negatively with youth engagement. Taken as a whole, these findings have important implications for researchers, practitioners, and policymakers interested in understanding the characteristics of out-of-school time programs that engage older youth. 相似文献
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This study examined quality and afterschool program designs with a focus on conditions of persistent low quality. Using an action science case study method, data from a quality-improvement project were examined to explore circumstances and reasons for low quality. Four identified program designs varied by emphasis on academics, school alignment, physical space, resources, and grouping strategies, as well as by the operationalization of youth choice. These program design features were found to be dynamically interrelated and key elements of structural quality yet were not found to be targets of state, funder, or agency quality improvement interventions guided by the current broad theory of change for quality initiatives. Structural quality, conceptualized as dynamic and interdependent, may be a prerequisite condition for self-directed quality improvement or a focus of targeted quality interventions. 相似文献
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