Confusingly enough the Sidon sequences of interest to me have a role to play in certain problems connected with the other type of Sidon sequence, as was discovered by Rudin. Fulvio Riccio , Scuola Normale, Sup. These include periodic waves radiating from space curves defined by a phase singularity. In the laboratory these form closed rings that shrink and vanish. In numerical experiments with the corresponding parabolic PDE of reaction and diffusion the rings can also link and knot, making the rings topologically stable.
Activity then persists indefinitely.
A polygon is called rational if all angles are rational multiples of pi. I will discuss these constructions and some associated problems in combinatorial enumeration. There are however exceptions to full ionization which while very non-generic include rather simple explicit functions. However, those models involve closure approximations that result in unpredictable errors in the complex flows that they are employed. Fortunately, in the last decade new methodologies has emerged that allow for such solutions to be obtained at significantly less computational cost through the coupling of a stochastic solution for the polymer chain configuration to a more traditional macroscopic finite-element or spectral flow approximation of the momentum and continuity equations.