Responsive open learning environments (ROLEs) are characterized through their openness for new configurations, new contents and new users, and through their responsiveness to learners' activities in respect to learning goals. Openness specifically encompasses the ability to include new learning...

In this paper, we present a standard quality ladders endogenous growth model with one significant new assumption, that it takes time for firms to learn how to export. We show that this model without Melitz-type assumptions can account for all the evidence that the Melitz (2003) model was...