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The impact of high temperatures (24 to 39 degrees C) and low to moderately high humidities (20 to 70%) on the applicability of TLC systems for drug identification was studied during a 6 month climatologic cycle in Burkina Faso (West Africa). In general, the Rf values as observed on the plates were found to be substantially affected as compared with values obtained at temperate climates. Some TLC systems were more affected than others and the largest deviations of up to 30 Rf units were at low humidities. Tropical conditions also had a negative effect on the reproducibility of Rf values. However, when an Rf-correction procedure was applied, using reference mixtures of known drugs on each plate, accuracy as well as reproducibility of the resulting Rfc values were drastically improved and data thus corrected were found to be compatible with existing TLC data bases developed under moderate climatological conditions. The impact of high to extremely high humidities (70 to 100%) remains to be investigated. 相似文献
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When does the Gender Difference in Rumination Begin? Gender and Age Differences in the Use of Rumination by Adolescents 总被引:1,自引:0,他引:1
A cross-sectional non-clinical sample of 1,218 adolescents, aged 10–17 years, completed measures of stress, rumination, and
depression to allow tests of the response style theory of S. Nolen-Hoeksema [J Res Adolesc 4:519–534, 1994] in adolescents,
in particular whether increasing levels of stress and rumination in early adolescence are predictive of the onset of the gender
difference in depression. Overall, females reported higher levels of stress, rumination, and depression than males. The onset
of the gender differences in stress and depression occurred at age 13 years, and for rumination one year earlier at 12 years.
Significantly, also from 13 years, rumination explained the gender difference in depression by showing that it significantly
mediated the effect of gender on depression. Gender moderated the rumination to depression relationship; specifically the
association was stronger for females than males. Developmental differences were noted in that rumination significantly mediated
between stress and depression earlier in the age range for females than males. Results supported many of the predictions of
Nolen-Hoeksema’s model of the emergence of a gender difference in adolescent depression.
相似文献
Isobel BrownEmail: |
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Michelle Marie Johns Marc Zimmerman Jose A. Bauermeister 《Journal of youth and adolescence》2013,42(1):82-95
Identity-based conceptualizations of sexual orientation may not account adequately for variation in young women’s sexuality. Sexual minorities fare worse in psychosocial markers of wellbeing (i.e., depressive symptoms, anxiety, self esteem, social support) than heterosexual youth; however, it remains unclear whether these health disparities exclusively affect individuals who adopt a sexual minority identity or if they also may be present among heterosexually-identified youth who report same-sex attractions. We examined the relationship between sexual attraction, sexual identity, and psychosocial wellbeing in the female only subsample (weighted, n = 391) of a national sample of emerging adults (age 18–24). Women in this study rated on a scale from 1 (not at all) to 5 (extremely) their degree of sexual attraction to males and females, respectively. From these scores, women were divided into 4 groups (low female/low male attraction, low female/high male attraction, high female/low male attraction, or high female/high male attraction). We explored the relationship between experiences of attraction, reported sexual identity, and psychosocial outcomes using ordinary least squares regression. The results indicated sexual attraction to be predictive of women’s psychosocial wellbeing as much as or more than sexual identity measures. We discuss these findings in terms of the diversity found in young women’s sexuality, and how sexual minority status may be experienced by this group. 相似文献
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The present study examined the longitudinal links between perceptions of family connectedness and body satisfaction in 1,774
(52% female) adolescents. Participants (10–15 years of age at Time 1) completed self-report measures at three measurement
occasions separated by 1 year each. Mean group difference results showed that both body satisfaction levels and perceived
levels of family connectedness decreased over 2 years for the whole sample. As expected, girls were generally less satisfied
with their bodies than boys, particularly in the older cohort. Structural equation modelling was used to assess stability
coefficients and cross-lagged effects, and longitudinal bidirectional effects between perceptions of family connectedness
and body satisfaction were found for girls, but not for boys. This result suggests that adolescent girls’ body satisfaction
is both affected by and a predictor of perceived family connectedness. 相似文献
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Latkoczy C Becker S Dücking M Günther D Hoogewerff JA Almirall JR Buscaglia J Dobney A Koons RD Montero S van der Peijl GJ Stoecklein WR Trejos T Watling JR Zdanowicz VS 《Journal of forensic sciences》2005,50(6):1327-1341
Forensic analysis of glass samples was performed in different laboratories within the NITE-CRIME (Natural Isotopes and Trace Elements in Criminalistics and Environmental Forensics) European Network, using a variety of Laser Ablation Inductively Coupled Plasma Mass Spectrometry (LA-ICP-MS) systems. The main objective of the interlaboratory tests was to cross-validate the different combinations of laser ablation systems with different ICP-MS instruments. A first study using widely available samples, such as the NIST SRM 610 and NIST SRM 612 reference glasses, led to deviations in the determined concentrations for trace elements amongst the laboratories up to 60%. Extensive discussion among the laboratories and the production of new glass reference standards (FGS 1 and FGS 2) established an improved analytical protocol, which was tested on a well-characterized float glass sample (FG 10-1 from the BKA Wiesbaden collection). Subsequently, interlaboratory tests produced improved results for nearly all elements with a deviation of < 10%, demonstrating that LA-ICP-MS can deliver absolute quantitative measurements on major, minor and trace elements in float glass samples for forensic and other purposes. 相似文献