Figure 1

(a) ${\mathrm{K}}^{+}$ current $I(t)$ through biological channel (BIO, red) excited at 60 mV, PET nanopore (PET, black) and Kapton nanopore (KPT, blue) at 180 mV. Note differences in scales. (b) Nonsmoothed power spectra of time series shown in (a) of biological BIO channel (red), and synthetic: PET (black) and KPT (blue) pores. BIO and PET channels work at bistable (open/closed) region, KPT channel—in monostable (open) region. $S(f)$ in $(\mathrm{p}\mathrm{A}{)}^2/\mathrm{H}\mathrm{z}$, $f$ in Hz. KPT-pore data are shifted down by one decade unit; otherwise spectra would obscure each other.Reuse & Permissions

Figure 2

Smoothed power spectra. Potassium current series data: PET pore excited at different voltages (line labels, black), biological channel BIO (red)—these spectra are in $(\mathrm{p}\mathrm{A}{)}^2/\mathrm{H}\mathrm{z}={10}^{-24}{\mathrm{A}}^2·\mathrm{s}$; dwell-time series (blue) for bistable channels: biological (label BIO) and synthetic (label PET)—these spectra are in $(\mathrm{m}\mathrm{s}{)}^2/\mathrm{H}\mathrm{z}={10}^{-6}{\mathrm{s}}^3$.Reuse & Permissions

Figure 3

Power spectra for artificially mixed bistable ${\mathrm{K}}^{+}$-current data. (a) Dwell times from PET potassium current series excited at 180 mV; (b) dwell times generated randomly with exponential distribution $P(t_d)=\exp (-t_d/{\tau }_{rnd})$; ${\tau }_{rnd}={\tau }_{\mathrm{P}\mathrm{E}\mathrm{T}}=73\mathrm{m}\mathrm{s}$. Current values taken as follows: black—PET 60 mV series (closed channel) and PET 250 mV series (open channel); blue—chosen randomly from two Gaussian distributions, peaked at 0 (closed channel) and 59 pA (open channel); red—constant values 0 (closed channel) and 59 pA (open channel).Reuse & Permissions

Figure 4

Non-markovian measure $G(\tau )$ [Eq. (2)] for bistable potassium current data—biological (BIO) and synthetic PET excited at 180 mV; time range $T=60\mathrm{m}\mathrm{s}$. $G(\tau )$ for markovian dichotomous series is shown as a dashed line at the bottom.Reuse & Permissions