We present a continuous-time generalization of the seminal R&D model of d’Aspremont and Jacquemin (The American Economic Review 78(5): 1133–1137, 1988) to examine the trade-off between the benefits of allowing firms to cooperate in R&D and the corresponding increased potential for product market collusion. We consider all trajectories that are candidates for an optimal solution as well as initi...

In a recent paper [C. DeW. Van Siclen, Phys. Rev. E 59, 2804 (1999)], a random-walk algorithm was proposed as the best method to calculate transport properties of composite materials. It was claimed that the method is applicable both to discrete and continuum systems. The limitations of the proposed algorithm are analyzed. We show that the algorithm does not capture the peculiarities of continu...

A method for controlling low-order chaotic behavior of continuous spatiotemporal systems is developed and demonstrated in a complex, realistic 3D partial differential equation model that is used successfully for predicting El Niño events in the equatorial Pacific. An unstable periodic orbit that involves a full-domain oscillation is stabilized using a feedback control applied to a single degree...

This paper examines the impact of restricting credit to payday borrowers. Using administrative banking data from over fifteen thousand online payday loan users, I exploit a natural experiment surrounding a 2013 U.S. Department of Justice initiative known as Operation Choke Point (OCP), which unexpectedly shut down dozens of online payday lenders. Using a difference in differences framework, I f...