Chapter 14

Diffusion Equation in
Spherical Coordinates

*Extract*: ...

Figure 1b: The spherical coordinate system used
in the analysis of diffusion in three dimensions, where
a source or sink of protein mass, *Q _{s}*, is created at the
cell centre. Simplified protein redistribution by
diffusion is illustrated in the text by two examples: the first by
solving at spherical grid points defined on the radial vector

*r*, assuming angular symmetry, i.e., no variations in polar angle or azimuthal angle, and the second by solving at spherical grid points on

*r*and polar angle grid points on, but assuming azimuthal angular symmetry, i.e., no variations in angle (image reproduced from [1] with permission of the authors).

1. Calvert, P. D., J. A. Peet,
A. Bragin, W. E. Schiesser and E. N. Pugh Jr., Fluorescence
Relaxation in 3D from Diffraction-limited Sources of PAGFP or Sinks of
EGFP Created by Multiphoton Photoconversion, *Journal of Microscopy*,
225, No. 1, January, 2007, pp. 49-71.