Arrive at or import a general ratio / concentration.

[pbuttigieg]

We require a class that represents concentrations and , both in a molecular sense (e.g. PATO:0000033) and in a count-based way (similar to PATO:0001470).

e.g. the concentration of "dissolved" organic carbon in water, the concentration of organisms that realise a prey role in a given area.

Related issues:
pato-ontology/pato#59