User:Jadrian Miles/Diffusion simulation

• Axon gauges in range 0.25 -- 10 μm (wzhou cite 1). "Extra-thick" axons (~20μm) are rare; about 3% occurrence at most, and only in certain structures.
• Hindered diffusion differs from free diffusion by a "tortuosity" value (Nicholson "Diffusion and related transport mechanisms" '01)
• Volume fraction is ~80% intra? (Nilsson MRI '08)
• Extracellular free D ~= 1.08 μm²/ms (ibid)
• τ_intra ~= 306 ms (but authors claim it's a bad fit) (ibid) (exchange times; see page 178 and ref 35)

Human histology would be useful: hand-compute volume fraction of intracellular fluid, extracellular fluid, and myelin, as well as axon gauges.