We investigate the role of the colored noise in two biological systems: (i) adults of Nezaraviridula (L.) (Heteroptera: Pentatomidae), and (ii) polymer translocation. In the first system we analyze,by directionality tests, the response of N. viridula individuals to subthreshold signals plus noise in theirmating behaviour. The percentage of insects that react to the subthreshold signal shows a nonmonotonicbehaviour, characterized by the presence of a maximum, as a function of the noise intensity. This is thesignature of the non-dynamical stochastic resonance phenomenon. By using a “soft” threshold model wefind that the maximum of the input-output cross correlation occurs in the same range of noise intensityvalues for which the behavioural activation of the insects has a maximum. Moreover this maximum valueis lowered and shifted towards higher noise intensities, compared to the case of white noise. In the secondbiological system the noise driven translocation of short polymers in crowded solutions is analyzed. Animproved version of the Rouse model for a flexible polymer is adopted to mimic the molecular dynamicsby taking into account both the interactions between adjacent monomers and the effects of a Lennard-Jones potential between all beads. The polymer dynamics is simulated in a two-dimensional domain bynumerically solving the Langevin equations of motion in the presence of thermal fluctuations and a colorednoise source. At low temperatures or for strong colored noise intensities the translocation process of thepolymer chain is delayed. At low noise intensity, as the polymer length increases, we find a nonmonotonicbehaviour for the mean first translocation time of the polymer centre of inertia. We show how colorednoise influences the motion of short polymers, by inducing two different regimes of translocation in thedynamics of molecule transport.
|Numero di pagine||14|
|Rivista||THE EUROPEAN PHYSICAL JOURNAL. B, CONDENSED MATTER PHYSICS|
|Stato di pubblicazione||Published - 2009|
All Science Journal Classification (ASJC) codes