TY - JOUR A1 - Schmidt, Isabelle A1 - Brunner, Martin A1 - Preckel, Franzis T1 - Effects of achievement differences for internal/external frame of reference model investigations BT - A test of robustness of findings over diverse student samples JF - British journal of educational psychology N2 - Background Achievement in math and achievement in verbal school subjects are more strongly correlated than the respective academic self-concepts. The internal/external frame of reference model (I/E model; Marsh, 1986, Am. Educ. Res. J., 23, 129) explains this finding by social and dimensional comparison processes. We investigated a key assumption of the model that dimensional comparisons mainly depend on the difference in achievement between subjects. We compared correlations between subject-specific self-concepts of groups of elementary and secondary school students with or without achievement differences in the respective subjects. Aims The main goals were (1) to show that effects of dimensional comparisons depend to a large degree on the existence of achievement differences between subjects, (2) to demonstrate the generalizability of findings over different grade levels and self-concept scales, and (3) to test a rarely used correlation comparison approach (CCA) for the investigation of I/E model assumptions. Samples We analysed eight German elementary and secondary school student samples (grades 3–8) from three independent studies (Ns 326–878). Method Correlations between math and German self-concepts of students with identical grades in the respective subjects were compared with the correlation of self-concepts of students having different grades using Fisher's Z test for independent samples. Results In all samples, correlations between math self-concept and German self-concept were higher for students having identical grades than for students having different grades. Differences in median correlations had small effect sizes for elementary school students and moderate effect sizes for secondary school students. Conclusions Findings generalized over grades and indicated a developmental aspect in self-concept formation. The CCA complements investigations within I/E-research. KW - academic self-concept KW - frame of reference KW - elementary school students KW - dimensional comparisons KW - internal/external frame-of-reference model Y1 - 2017 U6 - https://doi.org/10.1111/bjep.12198 SN - 0007-0998 SN - 2044-8279 VL - 88 IS - 4 SP - 513 EP - 528 PB - Wiley CY - Hoboken ER - TY - JOUR A1 - Sachse, Dirk A1 - Billault, Isabelle A1 - Bowen, Gabriel J. A1 - Chikaraishi, Yoshito A1 - Dawson, Todd E. A1 - Feakins, Sarah J. A1 - Freeman, Katherine H. A1 - Magill, Clayton R. A1 - McInerney, Francesca A. A1 - van der Meer, Marcel T. J. A1 - Polissar, Pratigya A1 - Robins, Richard J. A1 - Sachs, Julian P. A1 - Schmidt, Hanns-Ludwig A1 - Sessions, Alex L. A1 - White, James W. C. A1 - West, Jason B. A1 - Kahmen, Ansgar ED - Jeanloz, R T1 - Molecular Paleohydrology interpreting the Hydrogen- Isotopic Composition of Lipid Biomarkers from Photosynthesizing Organisms JF - Annual review of earth and planetary sciences JF - Annual Review of Earth and Planetary Sciences N2 - Hydrogen-isotopic abundances of lipid biomarkers are emerging as important proxies in the study of ancient environments and ecosystems. A decade ago, pioneering studies made use of new analytical methods and demonstrated that the hydrogen-isotopic composition of individual lipids from aquatic and terrestrial organisms can be related to the composition of their growth (i.e., environmental) water. Subsequently, compound-specific deuterium/hydrogen (D/H) ratios of sedimentary biomarkers have been increasingly used as paleohydrological proxies over a range of geological timescales. Isotopic fractionation observed between hydrogen in environmental water and hydrogen in lipids, however, is sensitive to biochemical, physiological, and environmental influences on the composition of hydrogen available for biosynthesis in cells. Here we review the factors and processes that are known to influence the hydrogen-isotopic compositions of lipids-especially n-alkanes-from photosynthesizing organisms, and we provide a framework for interpreting their D/H ratios from ancient sediments and identify future research opportunities. KW - paleoclimate KW - paleoclimate proxy KW - deuterium KW - organic geochemistry Y1 - 2012 SN - 978-0-8243-2040-9 U6 - https://doi.org/10.1146/annurev-earth-042711-105535 SN - 0084-6597 VL - 40 IS - 1 SP - 221 EP - 249 PB - Annual Reviews CY - Palo Alto ER - TY - JOUR A1 - Schmidt, Isabelle A1 - Brunner, Martin A1 - Keller, Lena A1 - Scherrer, Vsevolod A1 - Wollschlager, Rachel A1 - Baudson, Tanja Gabriele A1 - Preckel, Franzis T1 - Profile formation of academic self-concept in elementary school students in grades 1 to 4 JF - PLoS one Y1 - 2017 U6 - https://doi.org/10.1371/journal.pone.0177854 SN - 1932-6203 VL - 12 PB - PLoS CY - San Fransisco ER -