1. Israel Institute for Biological Research, P.O.B. 19, Ness‐Ziona 70450, Israel,
2. Biomedical Engineering & Instrumentation Program, NCRR, NIH, 13/3N17, Bethesda, MD 20892, U.S.A.,
3. Laboratory of Theoretical and Physical Biology, NICHD, NIH, 10/10D12 A, Bethesda, MD 20892, U.S.A.