Our indebtedness to Bernard rests upon his having reminded us. that we
view the terrain in all issues more clearly because we rest atop an i
ntellectual mountain created by our mentors, past and present. Thus we
are justly indebted to John Davidson and his seminal teachings on tra
nsport and reaction; an issue addressed here on the large (fluidised b
ed) medium (porous catalyst) and microscopic (human cell) scales.