TABLE 5.

Symbol key

Symbol	Definition
H	Height of the ROS.
R	Radius of the disks inside the ROS (disregarding incisures).
DR	Disk of radius R centered at the origin of R2.
m	Number of incisures.
Vj	Limiting jth incisures, assimilated to segments of length R – ro,j.
rj	Radial variable on Vj with origin at ro,j.
	Geometry of the jth incisure with tip at ro,j.
Deff	effective domain of the activation cascade.
k	Number of distinct activated disks each by a single photon.
D*i, eff	ith activated disk.
Ω	DR × (0, H) limiting cylinder enclosing the stack of disks DR.
Ωeff	Deff × (0, H) limiting domain available for diffusion of cGMP and Ca2+.
Bj	Vj × (0, H) limiting vertical rectangles cut on the limiting ROS by the limiting incisures aligned in series.
S	Limiting outer shell (same as lateral boundary of Ω).
dη	Surface measure on S.
ɛo	Width of each disk.
νɛo	Width of each interdiscal space.
σɛo	Width of the outer shell.
1 – μo	Volume ratio of cytosol to the volume of the ROS.
[cGMP]	[cGMP] in the interior of the limiting ROS.
[cGMP]*	[cGMP] in the activated disk(s).
[cGMP]S	[cGMP] in the limiting outer shell.
[cGMP]Bj	[cGMP] on Bj.
[Ca2+]	[Ca2+] in the interior of the limiting ROS.
[Ca2+]*	[Ca2+] in the activated disk(s).
[Ca2+]S	[Ca2+] in the limiting outer shell.
[Ca2+]Bj	[Ca2+] on Bj.
∇S	Gradient along the cylindrical variables of S.
	Gradient along the (rj, z) variables of Bj.
∇(x, y)	Gradient along the horizontal variables (x, y).