Quasinormal modes of a black hole with a cloud of strings in Einstein-Gauss-Bonnet gravity

The quasinormal modes for a scalar field in the background spacetime corresponding to a black hole, with a cloud of strings, in Einstein-Gauss-Bonnet gravity, and the tensor quasinormal modes corresponding to perturbations in such spacetime, were both calculated using the WKB approximation. In the obtained results we emphasize the role played by the parameter associated with the string cloud, comparing them with the results already obtained for the Boulware-Deser metric. We also study how the Gauss-Bonnet correction to general relativity affects the results for the quasinormal modes, comparing them with the same background in general relativity.Comment: 15 pages, 7 figures; To appear in IJMP

Multiplicity of endemic equilibria for a diffusive SIS epidemic model with mass-action transmission mechanism

We study a diffusive SIS epidemic model with mass-action transmission mechanism and show, under appropriate assumptions on the parameters, the existence of multiple endemic equilibria when the basic reproduction number, $\mathcal{R}_0$, is either less than one or greater than one. Previous studies have left open the question of extinction of disease or persistence when $\mathcal{R}_0<1$. Our results settle completely this open question. Results on the nonexistence/existence and uniqueness of endemic equilibrium are also presented

Traveling wave solutions for two species competitive chemotaxis systems

In this paper, we consider two species chemotaxis systems with Lotka–Volterra competition reaction terms. Under appropriate conditions on the parameters in such a system, we establish the existence of traveling wave solutions of the system connecting two spatially homogeneous equilibrium solutions with wave speed greater than some critical number c∗. We also show the non-existence of such traveling waves with speed less than some critical number c∗0 , which is independent of the chemotaxis. Moreover, under suitable hypotheses on the coefficients of the reaction terms, we obtain explicit range for the chemotaxis sensitivity coefficients ensuring c∗ = c∗0 , which implies that the minimum wave speed exists and is not affected by the chemoattractant