Fig. 1.
Fusion pores modeled as toroidal (a) and ellipsoidal (b) surfaces of revolution around the z-axis. Rp is the pore radius from the central axis to the central plane of the bilayer. Rb is half the limiting separation between the parallel bilayer midplanes (b) as well as a principal (meridian) radius of curvature of the toroid (a). The angle φ is used to parameterize the ellipse (Eqs. 2a and 2b). The horizontal axis and contour normal form an angle, θ, which is useful in calculating R2 (the parallel radius of curvature) with the aid of Meunier's theorem (see text)