The Effects of Context-based Problem-solving Tasks on Students’ Interest and Metacognitive Experiences

Prior knowledge, motivational factors, and metacognition have been long considered basic elements for successful problem-solving process. However, the interplay of these variables with context-based task characteristics has rarely been explored in research. The present study aimed at investigating how context-based task characteristics influence these three elements, and further expands to explore potential differentiated effects across physics’ topics. A multivariate analysis of covariance was conducted with 232 participants from high-track schools in Germany to investigate the effects of task characteristics and task topic with regard to their motivational and metacognitive variables. Overall results indicated that students’ situational interest and estimate of solution correctness decrease through time as a result from their interaction with the tasks characteristics. Furthermore, between-subject factor analyses revealed important differences across the task topics of mechanics and thermodynamics. Finally, the covariate of prior knowledge was positively significant across all analyses. The findings demonstrate the importance of appropriate design of context-based tasks to positively influence students’ motivation and metacognitive processing. Implications of the results, as well as further lines of research are discussed.

Super-resolution microscopy reveals majorly mono- and dimeric presenilin1/γ-secretase at the cell surface

γ-Secretase is a multi-subunit enzyme whose aberrant activity is associated with Alzheimer’s disease and cancer. While its structure is atomically resolved, γ-secretase localization in the membrane in situ relies mostly on biochemical data. Here, we combined fluorescent tagging of γ-secretase subunits with super-resolution microscopy in fibroblasts. Structured illumination microscopy revealed single γ-secretase complexes with a monodisperse distribution and in a 1:1 stoichiometry of PSEN1 and nicastrin subunits. In living cells, sptPALM revealed PSEN1/γ-secretase mainly with directed motility and frequenting ‘hotspots’ or high track-density areas that are sensitive to γ-secretase inhibitors. We visualized γ-secretase association with substrates like amyloid precursor protein and N-cadherin, but not with its sheddases ADAM10 or BACE1 at the cell surface, arguing against pre-formed megadalton complexes. Nonetheless, in living cells PSEN1/γ-secretase transiently visits ADAM10 hotspots. Our results highlight the power of super-resolution microscopy for the study of γ-secretase distribution and dynamics in the membrane.

Stratification with Honors: A Case Study of the “High” Track within United States Higher Education

At present, U.S. postsecondary sorting is best evidenced by an increasingly stratified system of higher education. However, very little attention is paid to even deeper levels of stratification within colleges and universities where academic tracking and its consequences are manifest. Given this significant lack of attention to deepening levels of stratification within many of the most “accessible” postsecondary institutions in the U.S., the purpose of this article is threefold: (1) to introduce readers to the notion of academic tracking within the postsecondary sector, (2) to situate honors education within the U.S. postsecondary tracking structure, and (3) to demonstrate the depths of stratification within a system that is lauded as the contemporary architect of social mobility. Based upon qualitative data collected during the 2016–2017 academic year at one public 4-year “accessible” university, findings illustrate the persistence, structure, and depths of stratification as an unintended consequence of one university’s efforts to reconcile the competing goals of excellence and equity.

About the influence of wheel-rail adhesion on the maximum speed of trains

Wheel-rail adhesion is a fundamental aspect in rail transport, with high impact on traction and braking of trains. In the case of high speeds trains, wheel-rail adhesion is particularly important, as the maximum usable traction force is limited by the adhesion force. The present paper analyses the influence of wheel-rail adhesion on the maximum speed of trains, considering ranges of usual values for the track gradient and the adhesion coefficient and the real data of two Japanese high-speed trains. Analysis shows that low adhesion and high track gradient result in significant reduction of train speed.