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Clusters appear in nature in a diversity of contexts, involving distances as long as the cosmological ones, and down to atoms and molecules and the very small nuclear size. They also appear in several other scenarios, in particular in biological systems as in ants, bees, birds, fishes, gnus and rats, for instance. Here we describe a model composed of a set of female and male individuals that obeys simple rules that rapidly transform an uniform initial state into a single cluster that evolves in time as a stable dynamical structure. We show that the center of mass of the structure moves as a random walk, and that the size of the cluster engenders a power law behavior in terms of the number of individuals in the system. Moreover, we also examine other possibilities, in particular the case of two distinct species that can evolve to form one or two distinct clusters.
We investigate the problem of the predominance and survival of weak species in the context of the simplest generalization of the spatial stochastic rock-paper-scissors model to four species by considering models in which one, two, or three species ha
In this letter, we investigate the population dynamics in a May-Leonard formulation of the rock-paper-scissors game in which one or two species, which we shall refer to as weak, have a reduced predation or reproduction probability. We show that in a
We present a simple analytical model to describe the fast increase of deaths produced by the corona virus (COVID-19) infections. The D (deaths) model comes from a simplified version of the SIR (susceptible-infected-recovered) model known as SI model.
Reactive oxygen and nitrogen species (ROS and RNS) play important roles in various physiological processes (e.g., phagocytosis) and pathological conditions (e.g., cancer). The primary ROS/RNS, viz., hydrogen peroxide, peroxynitrite ion, nitric oxide,
An epidemiological model is developed for the spread of COVID-19 in South Africa. A variant of the classical compartmental SEIR model, called the SEIQRDP model, is used. As South Africa is still in the early phases of the global COVID-19 pandemic wit