STScI has continued the development of systems for HST data calibration. The calibration database system (CDBS) tracks information about all HST calibration files. CDBS has been rebuilt to be more automated and provide some additional capabilities for users. We have also begun investigating the requirements for an on-the-fly calibration system. This system would allow users to retrieve data tha...

The principal causes of cracking in prestressed concrete sleepers are the dynamic loads induced by track irregularities and imperfections in the wheel-rail contact and the in-phase and out-of-phase track resonances. The most affected points are the mid-span and rail-seat sections of the sleepers. Central and rail-seat crack detection require visual inspections, as legislation establishes, and i...

Previous studies about engagement in MOOCs has focused primarily on behavioral engagement and less attention has been paid to cognitive engagement. This may lead to incomplete or even incorrect understandings about students experience and learning in MOOCs. In this study, we use number of lectures watched as a proxy for behavioral engagement and number of pauses in lectures watched as a proxy f...

We consider a model of strategic trading with asymmetric information of an asset whose value follows a Brownian motion. An insider continuously observes a signal that tracks the evolution of the asset’s fundamental value. The value of the asset is publicly revealed at a random time. The equilibrium has two regimes separated by an endogenously determined time T . In [0 T ), the insider gradually...

We built software to support student reasoning about a phenomenon and development of hypotheses to explain it. The goal is to engage students in asking questions, generating hypotheses and testing predictions. Rashi, an intelligent tutor, tracks students’ investigations (e.g., hypotheses, questions, data collection, and inferences) and helps articulate how evidence and theories are related. The...

Ziel des Beitrags ist, einen Überblick über aktuelle Entwicklungen und Ausprägungen von MOOCs sowie die Erfahrungen und Ergebnisse aus der Untersuchung von zwei MOOCs vorzustellen, die 2011 und 2012 durchgeführt wurden. Besondere Schwerpunkte liegen dabei auf der Bedeutung und Ausprägung der Beteiligungsformen in den verschiedenen MOOC-Formaten, der Beteiligung in den beiden untersuchten MOOCs ...