Efficiency and persistence in models of adaptation

A cut-and-paste model which mimics a trial-and-error process of adaptation is introduced and solved. The model, which can be thought of as a diffusion process with memory, is characterized by two properties, efficiency and persistence. We establish a link between these properties and determine two transitions for each property, a percolation transition and a depinning transition. If the adaptation process is iterated, the antipersistent state becomes an attractor of the dynamics. Extensions to higher dimensions are briefly discussed.Comment: 4 pages, 4 figures, submitted to publicatio

To Embrace the Other

The article presents a speech by the head of the Pontifical Council for Promoting Christian Unity, Cardinal Walter Kasper, delivered at the council\u27s plenary assembly on November 14, 2006. The Cardinal summarized recent developments like the resolution of some of the Christological differences with the Oriental Orthodox churches. The Cardinal focused on the shifts in ecumenism and emphasized the need for a dialogue of truth based on love and return to the sources in Scripture and the liturgy

Closing the Door on the School of the Assassins

Relates the author\u27s experiences as a participant in a vigil commemorating the seventh anniversary of the murder of six Jesuit priests, their housekeeper and her teenage daughter at the University of Central America in El Salvador