Im Physikunterricht über Validität sprechen

Erstveröffentlichung in: MNU Journal 76(4), 2023Das Aufzeichnen und Auswerten quantitativer Daten hat einen zentralen Stellenwert nicht nur in der Physik, sondern auch im Physikunterricht. Schüler/innen sollen dabei unter anderem beurteilen, welche Schlussfolgerungen aus Daten gezogen werden können und welche nicht. Die Frage nach der Validität der Schlussfolgerungen wird dabei jedoch oft vernachlässigt. Im folgenden Beitrag beleuchten wir den Validitätsbegriff aus Sicht der Physik und des Physikunterrichts und zeigen an einer Beispielaufgabe auf, wie er mit Schüler/inne/n thematisiert werden kann

Mathe braucht man überall? Welche mathematischen Lernvoraussetzungen erwarten Hochschullehrende für Studiengänge außerhalb des MINT-Bereichs?

Welche mathematischen Lernvoraussetzungen sollten Studienanfängerinnen und Studienanfänger außerhalb des MINT-Bereichs mitbringen? Dieser Frage widmete sich die Delphi-Studie MaLeMINT-E. Der vorliegende Beitrag stellt die Studie vor, gibt Einblicke in ihre Ergebnisse und diskutiert Implikationen

Mathematische Lernvoraussetzungen für MINT-Studiengänge aus Sicht der Hochschulen

Welche mathematischen Lernvoraussetzungen erwarten Hochschullehrende der Mathematik von Studienanfängerinnen und -anfängern in MINT-Studiengängen? dieser Frage widmete sich die Delphi-Studie MaLeMINT. Der vorliegende Beitrag gibt Einblicke in die Studie, die Ergebnisse und ihre Rezeption

What’s mathematics doing here? The role of mathematics in German Physics Olympiad tasks

Physics competitions target at motivating students for engaging in physics and at promoting students talented in physics. Physics competitions also aim at conveying a picture of physics as a scientific discipline, going beyond regular physics classes in school, and should thus also include a more intense mathematization of physics problems. Given that physics students often struggle with mathematics, mathematics in the competition may pose a challenge beyond the intended physics challenge. The present paper therefore presents an analysis of theoretical tasks employed in the German Physics Olympiad. Mathematical requirements were (1) identified by analyzing sample solutions and (2) compared to mathematics curricula. Then, (3) the solutions were categorized regarding whether the mathematics employed was used in a tool-like manner, a structuring manner, or both. Findings indicate that the first competition round typically includes rather basic mathematical requirements which are addressed in lower secondary mathematics education. In the higher rounds, more advanced mathematics is needed, which is only taught in the last years of high school, or not taught at all. The structural role of mathematics proved to be essential in the analyzed tasks. Beside the (intended) physics challenges, participants thus have to deal with mathematics they have not learned at school and have to apply mathematics in a different way than is often done at school when participating in the competition. As a consequence, unintended negative effects may occur, potentially counteracting the aim to promote students talented in physics. Implications for science education and future research are discussed

An acoustically-driven biochip - Impact of flow on the cell-association of targeted drug carriers

The interaction of targeted drug carriers with epithelial and endothelial barriers in vivo is largely determined by the dynamics of the body fluids. To simulate these conditions in binding assays, a fully biocompatible in vitro model was developed which can accurately mimic a wide range of physiological flow conditions on a thumbnail-format cell-chip. This acoustically-driven microfluidic system was used to study the interaction characteristics of protein-coated particles with cells. Poly(D,L-lactide-co-glycolide) (PLGA) microparticles (2.86 {\pm} 0.95 {\mu}m) were conjugated with wheat germ agglutinin (WGA-MP, cytoadhesive protein) or bovine serum albumin (BSA-MP, nonspecific protein) and their binding to epithelial cell monolayers was investigated under stationary and flow conditions. While mean numbers of 1500 {\pm} 307 mm-2 WGA-MP and 94 {\pm} 64 mm-2 BSA-MP respectively were detected to be cell-bound in the stationary setup, incubation at increasing flow velocities increasingly antagonized the attachment of both types of surface-modified particles. However, while binding of BSA-MP was totally inhibited by flow, grafting with WGA resulted in a pronounced anchoring effect. This was indicated by a mean number of 747 {\pm} 241 mm-2 and 104 {\pm} 44 mm-2 attached particles at shear rates of 0.2 s-1 and 1 s-1 respectively. Due to the compactness of the fluidic chip which favours parallelization, this setup represents a highly promising approach towards a screening platform for the performance of drug delivery vehicles under physiological flow conditions. In this regard, the flow-chip is expected to provide substantial information for the successful design and development of targeted micro- and nanoparticulate drug carrier systems.Comment: 19 page

SNP array typing provides new insights in chromosomal nondisjunction

Background Maternal uniparental disomy (UPD) of chromosome 7 (upd(7)mat) accounts for approximately 10% of patients with Silver-Russell syndrome (SRS). For upd(7)mat and trisomy 7, a significant number of mechanisms have been proposed to explain the postzygotic formation of these chromosomal compositions, but all have been based on as small number of cases. To obtain the ratio of isodisomy and heterodisomy in UPDs (hUPD, iUPD) and to determine the underlying formation mechanisms, we analysed a large cohort of upd(7)mat patients (n = 73) by SNP array typing. Based on these data, we discuss the UPDs and their underlying trisomy 7 formation mechanisms. Results A whole chromosome 7 maternal iUPD was confirmed in 28.8%, a mixture or complete maternal hUPD in 71.2% of patients. Conclusions We could demonstrate that nondisjunction mechanism affecting chromosome 7 are similar to that of the chromosomes more frequently involved in trisomy (and/or UPD), and that mechanisms other than trisomic rescue have a lower significance than previously suspected. Furthermore, we suggest SNP array typing for future parent- and cell-stage-of origin studies in human aneuploidies as they allow the definite classification of trisomies and UPDs, and provide information on recombinational events and their suggested association with aneuploidy formation

DNA methylation at birth and lateral ventricular volume in childhood:a neuroimaging epigenetics study

Background: Lateral ventricular volume (LVV) enlargement has been repeatedly linked to schizophrenia; yet, what biological factors shape LVV during early development remain unclear. DNA methylation (DNAm), an essential process for neurodevelopment that is altered in schizophrenia, is a key molecular system of interest. Methods:In this study, we conducted the first epigenome-wide association study of neonatal DNAm in cord blood with LVV in childhood (measured using T1-weighted brain scans at 10 years), based on data from a large population-based birth cohort, the Generation R Study (N = 840). Employing both probe-level and methylation profile score (MPS) approaches, we further examined whether epigenetic modifications identified at birth in cord blood are: (a) also observed cross-sectionally in childhood using peripheral blood DNAm at age of 10 years (Generation R, N = 370) and (b) prospectively associated with LVV measured in young adulthood in an all-male sample from the Avon Longitudinal Study of Parents and Children (ALSPAC, N = 114). Results: At birth, DNAm levels at four CpGs (annotated to potassium channel tetramerization domain containing 3, KCTD3; SHH signaling and ciliogenesis regulator, SDCCAG8; glutaredoxin, GLRX) prospectively associated with childhood LVV after genome-wide correction; these genes have been implicated in brain development and psychiatric traits including schizophrenia. An MPS capturing a broader epigenetic profile of LVV – but not individual top hits – showed significant cross-sectional associations with LVV in childhood in Generation R and prospectively associated with LVV in early adulthood within ALSPAC. Conclusions: This study finds suggestive evidence that DNAm at birth prospectively associates with LVV at different life stages, albeit with small effect sizes. The prediction of MPS on LVV in a childhood sample and an independent male adult sample further underscores the stability and reproducibility of DNAm as a potential marker for LVV. Future studies with larger samples and comparable time points across development are needed to further elucidate how DNAm associates with this clinically relevant brain structure and risk for neuropsychiatric disorders, and what factors explain the identified DNAm profile of LVV at birth.</p