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Elmar Dammann Stefan Behrendt Florina Ştefănică Reinhold Nickolaus 《Zeitschrift für Erziehungswissenschaft》2016,19(2):351-374
This paper examines subject-specific structures and the levels achieved by students of Mechanical and Construction Engineering in the subject of Engineering Mechanics (EM). EM presents a major obstacle for students in the two courses of study mentioned. Until now, researchers have not examined which characteristics of the requirements in EM cause this obstacle. Initial efforts to address this research gap were made in the research project KoM@ING. Competence structure modelling confirms three dimensions of EM: statics, elastostatics and dynamics. This paper presents results on proficiency scaling for statics and dynamics. We found that the subject-specific mathematical requirements primarily explain the item difficulties. Moreover, the following features are relevant for item difficulty: the number of solution steps (for statics), the number of EM-specific terms and the content-specific features of complexity (for dynamics). The mathematical requirements and the content-specific features of complexity are revealed as important didactic elements in this higher education context. 相似文献
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The structure and function of biological systems, for example, cells and proteins, depend strongly on their chemical environment. To investigate such dependence, we design a polydimethylsiloxane-based microfluidic device to encapsulate biological systems in picoliter-sized drops. The content of each individual drop is tuned in a defined manner. As a key feature of our method, the individual chemical composition is determined and related to the drop content. In our case, the drop content is imaged using microscopy methods, while the drops are immobilized to allow for long-time studies. As an application of our device, we study the influence of divalent ions on vimentin intermediate filament networks in a quantitative way by tuning the magnesium concentration from drop to drop. This way we are able to directly image the effect of magnesium on the fluorescently tagged protein in a few hundreds of drops. Our study shows that with increasing magnesium concentration in the drops, the compaction of the networks becomes more pronounced. The degree of compaction is characterized by different morphologies; freely fluctuating networks are observed at comparatively low magnesium concentrations of 5–10 mM, while with increasing magnesium concentration reaching 16 mM they develop into fully aggregated networks. Our approach demonstrates how a systematic study of interactions in biological systems can benefit from the exceptional controllability of microfluidic methods. 相似文献
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