Figure 4. Fluctuation of the internal segments of (A) T4 DNA in 80 nm 130 nm, (B) T4 DNA in 60 nm 100 nm and (C) DNA in 50 nm 70 nm channels.

For all cases, the maximum mean extension m. For (A) and (B), the data m agrees with de Gennes's theory (red, no fitting parameters). Deviation from de Gennes' theory begins at a critical m, above which the data falls into the black curve predicted by the deflection theories of Odijk [6], Wang and Gao [11]. For tighter channels (C), the transition occurs earlier with most data falling in the deflection regime.