Modelling Mathematical Reasoning in Physics Education

Many findings from research as well as reports from teachers describe students' problem solving strategies as manipulation of formulas by rote. The resulting dissatisfaction with quantitative physical textbook problems seems to influence the attitude towards the role of mathematics in physics education in general. Mathematics is often seen as a tool for calculation which hinders a conceptual understanding of physical principles. However, the role of mathematics cannot be reduced to this technical aspect. Hence, instead of putting mathematics away we delve into the nature of physical science to reveal the strong conceptual relationship between mathematics and physics. Moreover, we suggest that, for both prospective teaching and further research, a focus on deeply exploring such interdependency can significantly improve the understanding of physics. To provide a suitable basis, we develop a new model which can be used for analysing different levels of mathematical reasoning within physics. It is also a guideline for shifting the attention from technical to structural mathematical skills while teaching physics. We demonstrate its applicability for analysing physical-mathematical reasoning processes with an example.

New activity in the large circumstellar disk of the Be-shell star 48 Librae

Aims. Spectroscopic, polarimetric, and high spectral resolution interferometric data covering the period 1995-2011 are analyzed to document the transition into a new phase of circumstellar disk activity in the classical Be-shell star 48 Lib. The objective is to use this broad data set to additionally test disk oscillations as the basic underlying dynamical process. Methods. The long-term disk evolution is described using the V/R ratio of the violet and red emission components of H alpha and Br gamma, radial velocities and profiles of He I and optical metal shell lines, as well as multi-band BVRI polarimetry. Single-epoch broad-band and high-resolution interferometric visibilities and phases are discussed with respect to a classical disk model and the given baseline orientations. Results. Spectroscopic signatures of disk asymmetries in 48 Lib vanished in the late nineties but recovered some time between 2004 and 2007, as shown by a new large-amplitude and long-duration V/R cycle. Variations in the radial velocity and line profile of conventional shell lines correlate with the V/R behavior. They are shared by narrow absorption cores superimposed on otherwise seemingly photospheric He I lines, which may form in high-density gas at the inner disk close to the photosphere. Large radial velocity variations continued also during the V/R-quiet years, suggesting that V/R may not always be a good indicator of global density waves in the disk. The comparison of the polarization after the recovery of the V/R activity shows a slight increase, while the polarization angle has been constant for more than 20 years, placing tight limits on any 3-D precession or warping of the disk. The broad H-band interferometry gives a disk diameter of (1.72 +/- 0.2) mas (equivalent to 15 stellar radii), position angle of the disk (50 +/- 9)degrees and a relatively low disk flattening of 1.66 +/- 0.3. Within the errors the same disk position angle is derived from polarimetric observations and from photocenter shifts across Br gamma. The high-resolution interferometric visibility and phase profiles show a double or even multiple-component structure. A preliminary estimate based on the size of the Br gamma emitting region indicates a large diameter for the disk (tens of stellar radii). Overall, no serious contradiction between the observations and the disk-oscillation model could be construed.

Fidelity and game-based technology in management education

This study explores educational technology and management education by analyzing fidelity in game-based management education interventions. A sample of 31 MBA students was selected to help answer the research question: To what extent do MBA students tend to recognize specific game-based academic experiences, in terms of fidelity, as relevant to their managerial performance? Two distinct game-based interventions (BG1 and BG2) with key differences in fidelity levels were explored: BG1 presented higher physical and functional fidelity levels and lower psychological fidelity levels. Hypotheses were tested with data from the participants, collected shortly after their experiences, related to the overall perceived quality of game-based interventions. The findings reveal a higher overall perception of quality towards BG1: (a) better for testing strategies, (b) offering better business and market models, (c) based on a pace that better stimulates learning, and (d) presenting a fidelity level that better supports real world performance. This study fosters the conclusion that MBA students tend to recognize, to a large extent, that specific game-based academic experiences are relevant and meaningful to their managerial development, mostly with heightened fidelity levels of adopted artifacts. Agents must be ready and motivated to explore the new, to try and err, and to learn collaboratively in order to perform.

New insights in osteogenic differentiation revealed by mass spectrometric assessment of phosphorylated substrates in murine skin mesenchymal cells

Abstract Background Bone fractures and loss represent significant costs for the public health system and often affect the patients quality of life, therefore, understanding the molecular basis for bone regeneration is essential. Cytokines, such as IL-6, IL-10 and TNFα, secreted by inflammatory cells at the lesion site, at the very beginning of the repair process, act as chemotactic factors for mesenchymal stem cells, which proliferate and differentiate into osteoblasts through the autocrine and paracrine action of bone morphogenetic proteins (BMPs), mainly BMP-2. Although it is known that BMP-2 binds to ActRI/BMPR and activates the SMAD 1/5/8 downstream effectors, little is known about the intracellular mechanisms participating in osteoblastic differentiation. We assessed differences in the phosphorylation status of different cellular proteins upon BMP-2 osteogenic induction of isolated murine skin mesenchymal stem cells using Triplex Stable Isotope Dimethyl Labeling coupled with LC/MS. Results From 150 μg of starting material, 2,264 proteins were identified and quantified at five different time points, 235 of which are differentially phosphorylated. Kinase motif analysis showed that several substrates display phosphorylation sites for Casein Kinase, p38, CDK and JNK. Gene ontology analysis showed an increase in biological processes related with signaling and differentiation at early time points after BMP2 induction. Moreover, proteins involved in cytoskeleton rearrangement, Wnt and Ras pathways were found to be differentially phosphorylated during all timepoints studied. Conclusions Taken together, these data, allow new insights on the intracellular substrates which are phosphorylated early on during differentiation to BMP2-driven osteoblastic differentiation of skin-derived mesenchymal stem cells.