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. 2011 Feb 4;230(2):87–95. doi: 10.1016/j.mbs.2011.01.005

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Copyright © 2011 Elsevier Inc. All rights reserved.

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Fig. 1 — Illustration of the nature of the intersections in the $(I_{1}, I_{2})$ -plane of the curves $g_{1} (I_{1})$ and $g_{2} (I_{2})$ defined by (3.8a), (3.8b), when (a) $R_{0} < 1$ and (b) $R_{0} > 1$ .