Chaotic systems share with stochastic processes several properties that make them almost undistinguishable. In this communication we introduce a representation space, to be called the complexity-entropy causality plane. Its horizontal and vertical axis are suitable functionals of the pertinent probability distribution, namely, the entropy of the system and an appropriate statistical complexity measure, respectively. These two functionals are evaluated using the Bandt-Pompe recipe to assign a probability distribution function to the time series generated by the system. Several well-known model-generated time series, usually regarded as being of either stochastic or chaotic nature, are analyzed so as to illustrate the approach. The main achievement of this communication is the possibility of clearly distinguishing between them in our representation space, something that is rather difficult otherwise.

We consider a model for population dynamics such as for the evolution of bacterial colonies which is of the Fisher type but where the competitive interaction among individuals is nonlocal, and show that spatial structures with interesting features emerge. These features depend on the nature of the competitive interaction as well as on its range, specifically on the presence or absence of tails in, and the central curvature of, the influence function of the interaction.

The interaction between swift charged particles and the electronic surface modes of a cylindrical cavity is described according to classical and quantum-mechanical formulations. We perform a quantization of the collective modes and obtain expressions for the coupling with external probes moving with arbitrary trajectories. We study the case of particles moving parallel to the channel axis and derive the probabilities of single and multiple plasmon excitation and the average energy loss. A correspondence between the classical and quantum pictures is shown. The scaling properties of the interaction terms are studied and general scaling functions are obtained, which may be applied to a wide range of particle velocities and cavity sizes, including microcapillaries and nanotubes.