Topological methods Neumann boundary conditions Nonlinear boundary value problems Third order ODE's Three-ion electrodiffusion Topological index Two-ion electro-diffusion Unequal valencies Boundary conditions Boundary value problem Existence of solutions Painleve Astronomía Boundary value problems Boundary values CRECIMIENTO Diffusion Dirichlet boundary condition Dirichlet boundary conditions Dirichlet type Electrodiffusion Ermakov invariant Ermakov-Painlevé reduction Ermakov-Ray-Reid systems Existence and uniqueness results Existence of Solutions Existence results Galaxia Half lines I-V equation