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Arpan Dey

Publications and source records attributed to Arpan Dey.

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Collective drift and pinning in active rotator networks with Kuramoto coupling and mixed-sign feedback disorder

Active rotator models provide a minimal phase description of excitable and oscillatory systems, and have long been used to study mutual entrainment, synchronization, and collective transitions. Here, we investigate fully connected active rotator networks with Kuramoto coupling, where a common intrinsic drive competes with local feedback amplitudes drawn from a zero-mean Gaussian distribution. This produces a competition between local pinning and collective phase alignment. Using mean absolute late-time drift and the fractions of positive and negative drifting oscillators, we construct numerical regime maps in the feedback-disorder-coupling plane. At weak coupling, increasing the feedback disorder strength suppresses drift, while stronger coupling can restore positive late-time drift when feedback disorder is not too strong. We interpret these regimes using analytical limits for the uncoupled and coherent strong-coupling cases. We also examine finite-size effects and zero-mean distributed intrinsic frequencies. Together, these results show that mixed-sign local feedback alone can reshape the balance between pinning and drifting in coupled active rotator networks, even when the intrinsic drive is homogeneous.

nlin.AO

Mobility Heterogeneity in a 2D Gaussian Lattice Polymer: A Dynamic Monte Carlo Study

We study mobility heterogeneity in a two-dimensional Gaussian lattice polymer using dynamic Monte Carlo simulations. The polymer dynamics is generated from a local three-monomer move dictionary, which explicitly enumerates allowed bond-preserving updates on a square lattice. As a homogeneous benchmark, this dictionary reproduces the expected Rouse-like behavior of an ideal chain, including the crossover in monomer mean-squared displacement (MSD) and the center-of-mass diffusion scaling $D_{\rm cm} \sim N^{-1}$. We then introduce a two-block version of the model in which the two halves of the chain are updated with different attempt rates, $\omega_A$ and $\omega_B$, while the local move dictionary remains unchanged. For $\rho=\omega_A/\omega_B>1$, the more frequently updated block shows a larger block-resolved MSD at early and intermediate times, producing a positive normalized MSD asymmetry. However, numerical measurements show that the center-of-mass diffusion coefficient remains consistent with $D_{\rm cm} \sim N^{-1}$ for all rate ratios studied. We invoke a simple coarse-grained Rouse argument to explain this result analytically. In this minimal Gaussian setting, rate-induced mobility heterogeneity modifies internal relaxation without changing the Rouse scaling of center-of-mass transport.

cond-mat.soft