Look at behavior of the compartmental model

[aarmey]

I'd like to get a better understanding of how the compartmental model behaves. Specifically, I'm interested in whether there's accumulation of any species at the PS border during stimulation. Any sort of spatial pattern is something we could look at as validation of our results and model improvements.

@sumedha-k has parameters from fitting for all the binding rates. For the diffusivity on the surface, we'll just have to vary this and see how it affects the results over time.