In the spirit of Lewis Richardson’s original study of the statistics of deadly conflicts, we study the frequency and severity of terrorist attacks worldwide since 1968. We show that these events are uniformly characterized by the phenomenon of “scale invariance,†that is, the...

The motion in the plane of an harmonically bound charged particle interacting with a magnetic field and a half-plane barrier along the positive x-axis is studied. The magnetic field is perpendicular to the plane in which the particle moves. This motion is integrable in between collisions of the...

The immune system is a complex system that learns, remembers what it has learned, and acts to protect us from a variety of pathogens. Here we address the question of how the immune system is able to recognize and learn about pathogens that can rapidly evolve and hence potentially change so as to...

In many biophysical and biochemical experiments one observes the decay of some ligand population due to their capture by an appropriate system of traps. These experiments are usually interpreted under the assumption that the total number of free ligands decays as N(t) ≅ N0 exp(-tτ) for long...