Geophysical instruments show great potential for the detailed quantification of soil stratigraphy. In this study, two electromagnetic induction sensors were evaluated on their capacity to map small‐scale variations of the depth to the interface (zin) in a two‐layered soil. On a 2‐ha study site, zin between the silty topsoil and the contrasting clayey subsoil was modeled first by relating the two apparent electrical conductivity (ECa) measurements of the EM38DD sensor to observations of zin obtained by augering. A substantial number of these calibration observations was needed, however, to account for the modeling parameters. To avoid this step, an entirely noninvasive procedure was proposed based on one survey with the DUALEM‐21S sensor. This sensor simultaneously records four ECa values with different coil configurations. These measurements correspond to four different depth response functions that allow modeling zin without calibration observations. The only assumption was a two‐layered soil profile. The zin predictions were validated with 24 independent depth observations. Both procedures resulted in equal correlation coefficients (0.85) between predicted and measured zin and average estimation errors (0.26 m). This indicated that both sensors allowed the accurate mapping of the depth to a contrasting textural layer. With the EM38DD, calibration observations are needed, whereas the four different coil conurations of the DUALEM‐21S sensor provided sufficient information to predict the interface depth without augering.
Objectives: Androgen activity has been implicated in a range of traits and behaviours that have well-documented sex differences. However, the results of the studies on the relationship between testosterone and these traits and behaviours are inconsistent. This study has analyzed i) whether CAG repeat length, a presumed modulator of androgen receptor sensitivity, is associated with sex-dimorphic traits and behaviours (aggressive and non-aggressive risk-taking (ART and NART), dominance, depressive symptoms and self-esteem), and ii) whether CAG repeat length interacts with free testosterone (FT) with respect to these traits and behaviours. Design and methods: Data obtained from a group of adolescent boys (nZ301; mean age: 14.4 years) were analyzed using multivariate general linear modelling (SPSS, Chicago, IL, USA 15.0). Results: We found no direct correlation between CAG repeat length and dependent variables. We found significant interactions between CAG repeat length and testosterone, indicating that FT was more positively related to ART and NART with a shorter repeat length, and that an inverse association of FT with depressive symptoms and a positive association with self-esteem were stronger in boys with a longer CAG repeat length. Conclusion: Our findings indicate the importance of studying FT and CAG repeat length simultaneously with respect to sex-dimorphic traits, taking into account the possible interactions between the two.
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