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. 2011 Jul 8;6(7):e21960. doi: 10.1371/journal.pone.0021960

Figure 15. Model geometry.

Figure 15

A: Radii Inline graphic and Inline graphic of cells i and j, respectively, the sum of their spherical cap heights Inline graphic and the radius Inline graphic of their contact area Inline graphic. B: Side view of cell i on substrate Inline graphic with full cell radius Inline graphic, substrate adhesion radius Inline graphic, and substrate cap height Inline graphic. Podium cone geometry with base radius Inline graphic, podium tip radius Inline graphic (Inline graphic) and length Inline graphic of podium m. The length is measured from half Inline graphic to the center of the podium tip. C: podium position updates (contact guidance) in 2D. C1: shift of podium 1 of cell j away from podium 1 of cell i. C2: shift of podium 1 of cell k away from the body of cell i for small overlaps (analogously, for the spherical podium tip). C3: move of podium 1 of cell l towards the tangent line (T) of podium 2 of cell i if the overlapping podium exceeds the length of the tangent section (center of cell l to tangent point). The limiting line (L) between cases C2 and C3 is a spherical section. For small simulation step sizes and low cell densities C1 and C2 will generally suffice. Otherwise case C3 is employed to move a podium off another cell. However, full removal requires subsequent application of C1 or C2. Inline graphic and Inline graphic indicate the directional unit vector of podium 1 and 2 of cell i, respectively. The moved podia (cells j, k, l) are represented as their mid-line (dotted). Overlap between cells is defined by the intersection of this mid-line with the full podium of the respective resting cell (cell i) extended by the radius of the moved podium tip.