On CK, PCK and student dropout in the early phase of math (teacher) education at university

Die DIssertation beschreibt zentrale Themen der Lehrerbildung im Fach Mathematik. In einer theoretischen Auseinandersetzung, beginnend mit Lee S. Shulmans viel zitierten Artikeln von 1986 und 1987, wird auf mögliche Gliederungen des professionellen Wissens einer Lehrkraft eingegangen. Hierbei wird besonders der Begriff der Fachdidaktik genauer betrachtet, da diese (nach Shulman) als Übergang zwischen der Fachwissenschaft und der Pädagogik eine besondere Relevanz für die Lehrperson hat. Neben der Eingliederung der Fachdidaktik in die Topologie des professionellen Wissens einer Lehrkraft, spielt hierbei auch ihre innere Struktur eine zentrale Rolle. Dieses Thema wurde bereits von internationalen Forschergruppen behandelt, die erreichten Ergebnisse lassen aber Einigkeit und empirische Evidenz oft vermissen. In dieser Arbeit wird eine eigene Gliederung und Sichtweise, zusammen mit empirischen Ergebnissen vorgestellt. Ein weiterer, unbestreitbar relevanter Punkt in der Lehrerbildung ist die mathematisch, fachwissenschaftliche Ausbildung selbst. Es werden Analysen zur Prädiktion des Studienerfolgs im ersten Semester (Analysis 1) vorgestellt. Diese angewandten Prädiktionsmodelle basieren auf jüngeren statistischen Verfahren (aus dem Bereich des maschinellen Lernens) und erlauben, bereits zu Beginn des Studiums, eine Identifikation von Risikogruppen, aufgrund von wenigen, leicht zugänglichen Hintergrundinformationen der Studierenden. Die Ergebnisse erlauben eine differenzierte Betrachtung des Studienerfolgs von Mathematik Lehramtskandidatinnen und -kandidaten, im Vergleich zu ihren Kommilitoninnen und Kommilitonen

Design Methodology for the Electrification of Urban Bus Lines with Battery Electric Buses

Electrically powered buses reduce CO$_{2}$ and noise emissions in urban areas and thus promote the trend towards more livable cities. Upon this reason, more and more cities are introducing their first electrified lines as pilot projects. However, no standardized technology has yet emerged, which is why statements on interactions between vehicle, operation and infrastructure in public transport are proving to be difficult to make. In order to be able to make statistically significant statements in this respect, a simulation model was developed that depicts the three subsystems vehicle, operation and infrastructure. On the basis of measurement data from the PRIMOVE research project in Mannheim, in which an urban bus line is operated with two electrically powered buses, the simulation model was validated and a data basis was laid for further investigations. As a result, simulation studies with more than 700 simulated operating days could be carried out, the results of which represent the input for the following statistical analysis. Based on this analysis, the interactions described above will be demonstrated in the design of the main technical parameters, the battery lifespan and the energy demand of electrical bus lines. Through the findings of these simulations, an optimized version of the already electrified bus line in Mannheim will then be presented. Finally, a novel design methodology for electrification based on a multi-objective optimization is introduced. All parameters of the system are variable in order to apply the presented methodology to other projects and thus underline the general validity of the work

The spectral data for Hamiltonian stationary Lagrangian tori in R^4

This article determines the spectral data, in the integrable systems sense, for all weakly conformally immersed Hamiltonian stationary Lagrangian in $\R^4$. This enables us to describe their moduli space and the locus of branch points of such an immersion. This is also an informative example in integrable systems geometry, since the group of ambient isometries acts non-trivially on the spectral data and the relevant energy functional (the area) need not be constant under deformations by higher flows.Comment: 30 pages. Version 3: a complete rewrite of version 2 with new results and two significant correction

Atomic layer deposition-based tuning of the pore size in mesoporous thin films studied by in situ grazing incidence small angle x-ray scattering

Atomic layer deposition (ALD) enables the conformal coating of porous materials, making the technique suitable for pore size tuning at the atomic level, e.g., for applications in catalysis, gas separation and sensing. It is, however, not straightforward to obtain information about the conformality of ALD coatings deposited in pores with diameters in the low mesoporous regime (< 10 nm). In this work, it is demonstrated that in situ synchrotron based grazing incidence small angle x-ray scattering (GISAXS) can provide valuable information on the change in density and internal surface area during ALD of TiO2 in a porous titania film with small mesopores (3-8 nm). The results are shown to be in good agreement with in situ x-ray fluorescence data representing the evolution of the amount of Ti atoms deposited in the porous film. Analysis of both data sets indicates that the minimum pore diameter that can be achieved by ALD is determined by the size of the Ti-precursor molecule

3D/4D ultrasound registration of bone

This paper presents a method to reduce the invasiveness of Computer Assisted Orthopaedic Surgery (CAOS) using ultrasound. In this goal, we need to develop a method for 3D/4D ultrasound registration. The premilinary results of this study suggest that the development of a robust and ``realtime'' 3D/4D ultrasound registration is feasible

PFOS induces behavioral alterations, including spontaneous hyperactivity that is corrected by dexamfetamine in zebrafish larvae

Perfluorooctane sulfonate (PFOS) is a widely spread environmental contaminant. It accumulates in the brain and has potential neurotoxic effects. The exposure to PFOS has been associated with higher impulsivity and increased ADHD prevalence. We investigated the effects of developmental exposure to PFOS in zebrafish larvae, focusing on the modulation of activity by the dopaminergic system. We exposed zebrafish embryos to 0.1 or 1 mg/L PFOS (0.186 or 1.858 µM, respectively) and assessed swimming activity at 6 dpf. We analyzed the structure of spontaneous activity, the hyperactivity and the habituation during a brief dark period (visual motor response), and the vibrational startle response. The findings in zebrafish larvae were compared with historical data from 3 months old male mice exposed to 0.3 or 3 mg/kg/day PFOS throughout gestation. Finally, we investigated the effects of dexamfetamine on the alterations in spontaneous activity and startle response in zebrafish larvae. We found that zebrafish larvae exposed to 0.1 mg/L PFOS habituate faster than controls during a dark pulse, while the larvae exposed to 1 mg/L PFOS display a disorganized pattern of spontaneous activity and persistent hyperactivity. Similarly, mice exposed to 0.3 mg/kg/day PFOS habituated faster than controls to a new environment, while mice exposed to 3 mg/kg/day PFOS displayed more intense and disorganized spontaneous activity. Dexamfetamine partly corrected the hyperactive phenotype in zebrafish larvae. In conclusion, developmental exposure to PFOS in zebrafish induces spontaneous hyperactivity mediated by a dopaminergic deficit, which can be partially reversed by dexamfetamine in zebrafish larvae