A novel approach to chemotaxis: Active particles guided by internal clocks

Abstract

Motivated by the observation of non-exponential run-time distributions of bacterial swimmers, we propose a minimal phenomenological model for taxis of active particles whose motion is controlled by an internal clock. The ticking of the clock depends on an external concentration field, e.g., a chemical substance. We demonstrate that these particles can detect concentration gradients and respond to them by moving up-or down-gradient depending on the clock design, albeit measurements of these fields are purely local in space and instantaneous in time. Altogether, our results open a new route in the study of directional navigation: we show that the use of a clock to control motility actions represents a generic and versatile toolbox to engineer behavioral responses to external cues, such as light, chemical, or temperature gradients.

Wrapped Up: The Motility of Polarly Flagellated Bacteria

“…As chemoattractant concentrations are increased over time, the frequency of directional changes is decreased (33,34). This is in line with a classical chemotaxis strategy where runs in gradient direction elongate on average, compared to runs pointing away from the source of chemoattractant (80,86).…”

“…The run-time distribution of P. putida was found to be nonexponential (108), indicating that, in contrast to the case of E. coli, the duration of runs is controlled by a more complex underlying stochastic process (80). As chemoattractant concentrations are increased over time, the frequency of directional changes is decreased (33,34).…”

Pregnancy Outcome in Women with Heart Disease in a Tertiary Care Centre in Kolkata, India

“…Next, we focus on the stationary two-time velocity autocorrelation of a single oscillator, which can be obtained by putting l = l ′ in Eq. (45). Using Eqs.…”

“…One of the simplest ways to introduce a non-Markovian flipping protocol is to consider a Gamma-distribution P(t, τ ) = (t/τ 2 ) exp(−t/τ ) for the waiting time, where ⟨t⟩ = τ still characterizes the activity. The corresponding autocorrelation of the active force f l (t) in the time as well as in the frequency domain are given by [45,46],…”