University of Konstanz
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Transformation of Lead Iodide (Cs<sub>0.05</sub>PbI<sub>2.05</sub>) during Annealing and Its Influence on Perovskite Formation and Solar Cells
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Latent Reciprocal Engagement and Accuracy Variables in Social Relations Structural Equation Modeling
No full textThe social relations model (SRM) is the standard approach for analyzing dyadic data stemming from round-robin designs. The model can be used to estimate correlation-coefficients that reflect the overall reciprocity or accuracy of judgements for individual and dyads on the sample- or population level. Within the social relations structural equation modeling framework and on the statistical grounding of stochastic measurement and classical test theory, we show how the multiple indicator SRM can be modified to capture inter-individual and inter-dyadic differences in reciprocal engagement or inter-individual differences in reciprocal accuracy. All models are illustrated on an open-access round-robin data set containing measures of mimicry, liking, and meta-liking (the belief to be liked). Results suggest that people who engage more strongly in reciprocal mimicry are liked more after an interaction with someone and that overestimating one’s own popularity is strongly associated with being liked less. Further applications, advantages and limitations of the models are discussed.publishe
Morphological traits and machine learning for genetic lineage prediction of two reef-building corals
No full textIntegrating multiple lines of evidence that support molecular taxonomy analysis has proven to be a robust method for species delimitation in scleractinian corals. However, morphology often conflicts with genetic approaches due to high phenotypic plasticity and convergence. Understanding morphological variation among species is crucial to studying coral distribution, life history, ecology, and evolution. Here, we present an application of Random Forest models for coral species identification based on morphological annotation of the corallum and corallites. We show that the integration of molecular and morphological trait analysis can be improved using machine learning. Morphological traits were documented for Porites and Pocillopora coral species that were collected and genotyped through genome-wide, genetical hierarchical clustering, and coalescence analyses for the Tara Pacific Expedition. While Porites only included three tentative species, most Pocillopora species were accounted by included specimens from the western Indian Ocean, tropical Southwestern Pacific, and southeast Polynesia. Two Random Forest models per genus were trained on the morphological annotations using the genetic lineage labels. One model was developed for in-situ image identification and used corallum traits measured from in-situ photographs. Another model for integrative species identification combined corallum and corallite data measured on scanning electron micrographs. Random Forest models outperformed traditional dimension reduction methods like PCA and FAMD followed by k-means and hierarchical clustering by classifying the correct genetic lineage despite morphological clusters overlapping. This machine learning approach is reproducible, cost-effective, and accessible, reducing the need for taxonomic expertise. It can complement molecular and phylogenetic studies and support image identification, highlighting its potential to advance a coral integrative taxonomy workflow.publishe
Hidden quantum correlations in the ground states of quasiclassical spin systems
No full textFrustrated spin models may lead to the formation of both classical noncollinear spin structures and unique quantum phases including highly entangled quantum spin liquids. Here, we study the entanglement and spatial quantum correlations in linear spin-wave theory around a classical spin spiral ground state. We find that the entanglement between pairs of sites is short-ranged, and is completely absent in certain cases. In contrast, the entanglement hidden in multisite clusters is peaked close to phase transitions and shows an asymptotic behavior modulated by the period of the magnetic structure. These findings motivate further exploring the connection in the entanglement properties of fully quantum and of quasiclassical spin models.publishe
Dehydration-Driven Glass Formation in Aqueous Carbonates
No full textAmorphous carbonates, in their liquid and solid (glassy) forms, have been identified to play important roles in biomineralization, volcanism, and deep element cycling. Anhydrous amorphous calcium and calcium–magnesium carbonate (ACC and ACMC05, respectively) are structural glasses that exhibit a glass transition upon being heated. We report a significant effect of the water content on glass formation. The results yield a parametrization enabling prediction of the stability of their liquid and solid amorphous phases as a function of temperature and water content. These results, obtained through novel fast differential scanning calorimetry, demonstrate that hydrous ACC and ACMC05 do indeed exhibit the behavior of structural glasses and that dehydration of these materials by lyophilization is a route that can be used to isothermally cross the glass transition. This work presents a viable process for a significantly wider range of geo- and biomaterials. Dehydration-controlled formation of glassy ACC therefore constitutes the missing link in the transformation from supersaturated aqueous solutions through an intermediate amorphous glassy state to crystalline CaCO3 polymorphs. These results yield direct implications for the mechanistic interpretation of geological processes and biomineralization.publishe
Financial Literacy Games : Increasing Utility Value by Instructional Design in Upper Secondary Education
No full textEmpirical findings show that students often have insufficient financial literacy, even though they increasingly make independent financial decisions. Financial education at school can provide a foundation for a lifelong proactive approach to financial matters with increasing utility value and financial interest. This includes the simulation of future financial decisions with serious games. Despite a wide range of serious games to promote financial literacy, there is a lack of empirical research on the instructional design of such games. This includes the instructional design of game mechanics as action-guiding and reflection prompts for debriefing. In a quasi-experimental intervention study with a 2 × 2 research design, upper secondary students were assigned to four groups (n = 293). They played the game Moonshot with different combinations of game mechanics and reflection prompts. Based on mixed ANOVA analysis, the combination of strategic game mechanics and direct reflection prompts significantly increased students’ utility value for a financial literacy game, which underlines the importance of the instructional design of game mechanics and reflection prompts in serious games. But only a group-independent time effect was found for financial interest. Theoretical and practical implications are discussed.publishe
Einfluss von Umweltfaktoren auf die Abundanz und die Verteilung von Sturzbäumen an Seeufern in Brandenburg : Bericht der ARGE „Team Seeufer MMM“ für das Landesamt für Umwelt Brandenburg, Ref. W26
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Dropout analysis : A method for data from Internet-based research and dropR, an R-based web app and package to analyze and visualize dropout
No full textWith Internet-based research, non-response such as lack of responses to particular items and dropout have become interesting dependent variables due to highly voluntary participation and large numbers of participants (Reips, 2000, 2002b). In this article, we develop and discuss the methodology of using and analyzing dropout in Internet-based research, and we present dropR, an R package and web service (web application) to analyze and visualize dropout. The web app was written in R using Shiny, a free software environment for statistical computing and graphics. Among other features, dropR turns input from datasets into accessible and publication-ready visual displays of dropout curves. It calculates parameters relevant to dropout analysis, such as chi-square values and odds ratios for points of difference, initial drop, and percent remaining in stable states. It provides Kaplan–Meier survival statistics and tests survival curve differences. With automated inferential components, it identifies critical points in dropout and critical differences between dropout curves for different experimental conditions (Kolmogorov–Smirnov and rho-family statistics) and produces related statistical copy. Requiring no programming knowledge, dropR is provided as a free web application at https://dropr.eu and for programmers as an R package (under a cost free general public license, GPL-3, https://cran.r-project.org/web/licenses/GPL-3) from researchers for researchers. All code and materials are openly available on GitHub (https://github.com/iscience-kn/dropR).publishe
Are we heading towards a global decrease in coregonine catches?
No full textCoregonines have specific ecological needs, making them potentially very vulnerable to changes in lake conditions. A contemporary concern is that many lakes worldwide are experiencing environmental changes due to anthropogenic pressure and climate warming. Here, we compiled long-term data of coregonine catches from 27 lakes from three continents in the northern hemisphere. Declines in catch were observed in 67% of the lakes during the first two decades of the 21 st century, with a significant trend (p-value<0.05) in 44% of the cases. An analysis to determine whether trends are globally linked to environmental conditions and specific lake attributes was carried out on 26 lakes for the period 2000–2019. Several local declines in catches had already been documented in the literature and are likely to be due to local forcing such as nutrients, species invasions and changes in fishing practices. Nevertheless, on a global scale, our results indicate that lakes, which exhibited a significant decrease in catch were larger and more nutrient-poor than other lakes. The rate of change in catches appeared to be related to the trophic state of the lake. The specific effect of warming is difficult to determine during the studied period. When warming occurred outside the period of egg incubation, decreasing trends were more frequently observed in nutrient-poor than in mesotrophic lakes. In conclusion, our findings suggest that achieving oligo- or ultraoligotrophic conditions, as required in developed countries to control phytoplankton blooms and enhance water quality, could pose significant challenges for future management of coregonine fisheries.publishe
Extending Awareness of Open Science via Peers : The ERUA Open Science Ambassador Programme
No full textReaching researchers in terms of Open Science-related matters is a big challenge for Open Science professionals. To encourage peer exchange among researchers working at universities of the European Reform University Alliance (ERUA), we launched the ERUA Open Science Ambassador Programme. In this programme, four researchers working at different universities of the alliance took on the role as Open Science ambassadors. This paper illuminates the programme’s aims and discusses the risks we faced. It outlines how we got the programme going, explaining how we recruited our ambassadors, how we connected them, what knowledge and materials we equipped them with and how we communicated the programme within the alliance. Furthermore, the paper delineates the ambassadors’ activities, giving recommendations based on the challenges we encountered and the experiences we made. The paper is a valuable source of information for institutions that consider setting up similar Open Science ambassador programmes.publishe