How does rumination impact cognition? A first mechanistic model.

Rumination is a process of uncontrolled, narrowly-foused neg- ative thinking that is often self-referential, and that is a hall- mark of depression. Despite its importance, little is known about its cognitive mechanisms. Rumination can be thought of as a specific, constrained form of mind-wandering. Here, we introduce a cognitive model of rumination that we devel- oped on the basis of our existing model of mind-wandering. The rumination model implements the hypothesis that rumina- tion is caused by maladaptive habits of thought. These habits of thought are modelled by adjusting the number of memory chunks and their associative structure, which changes the se- quence of memories that are retrieved during mind-wandering, such that during rumination the same set of negative memo- ries is retrieved repeatedly. The implementation of habits of thought was guided by empirical data from an experience sam- pling study in healthy and depressed participants. On the ba- sis of this empirically-derived memory structure, our model naturally predicts the declines in cognitive task performance that are typically observed in depressed patients. This study demonstrates how we can use cognitive models to better un- derstand the cognitive mechanisms underlying rumination and depression

Back to the Future for African Infrastructure? Why State-Ownership Is No More Promising the Second Time Around

Too many African state-owned enterprises (SOEs), particularly those in infrastructure sectors, have a long history of poor performance. African governments and donors labored through the 1970s and 1980s to improve SOE performance through “commercialization”——i.e., methods short of ownership change. These generally failed, giving rise, in the 1990s, to much more heavy reliance on private sector participation and ownership. This approach produced some successes, but Africa’s private participation in infrastructure (PPI) initiatives have been comparatively few and weak. A number of those that have been launched have run into problems, to the point where both investor and African government interest in the approach has waned in the last few years. The reform is not popular—surveys of public opinion in 15 African countries reveal that only a third of respondents prefer private to state-owned firms. Nonetheless, African states (and their supporters) should not jettison the PPI approach. Rather, they should acknowledge its limitations, and recognize the large scope and moderate pace of the preparatory measures required both to improve their investment climates and to make PPI work effectively.privatization, private sector, African state-owned enterprise, commercialization, private participation in infrastructure

Vista D5.2 - Final Assessment Report

Vista examines the effects of conflicting market forces on European performance in ATM, through the evaluation of impact metrics on four key stakeholders, and the environment. Vista models the current, 2035 and 2050 timeframes based on various factors and their potential evolution. Vista’s model covers the three temporal phases of ATM (strategic, pre-tactical and tactical), and represents a typical (busy) day of operations. The model is able to estimate the impact of factors on the different phases independently, allowing us to capture how indicators change under different scenarios and execution phases. This deliverable presents the final results obtained from the model, together with a detailed description of the various parts of the model, the analysis performed to prepare the data, and the model calibration

The 1992 4th NASA SERC Symposium on VLSI Design

Papers from the fourth annual NASA Symposium on VLSI Design, co-sponsored by the IEEE, are presented. Each year this symposium is organized by the NASA Space Engineering Research Center (SERC) at the University of Idaho and is held in conjunction with a quarterly meeting of the NASA Data System Technology Working Group (DSTWG). One task of the DSTWG is to develop new electronic technologies that will meet next generation electronic data system needs. The symposium provides insights into developments in VLSI and digital systems which can be used to increase data systems performance. The NASA SERC is proud to offer, at its fourth symposium on VLSI design, presentations by an outstanding set of individuals from national laboratories, the electronics industry, and universities. These speakers share insights into next generation advances that will serve as a basis for future VLSI design