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We introduce a framework for studying collective search by teams. Discoveries are correlated over time and governed by a Brownian path, where search speed is jointly controlled. Agents individually choose when to cease search and implement their best discovery. We characterize equilibrium and optimal policies. Search speeds are constant within active alliances and depend on complementarities between members. A drawdown stopping boundary governs each agent’s search termination. The consequent exit waves, whereby possibly heterogeneous agents cease search simultaneously, exhibit deterministic sequencing but stochastic timing. We highlight environments with lower than optimal equilibrium speeds and search durations, and different exit waves.
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Escape dynamics of confined undulating worms
We investigate the escape dynamics of oligochaeta Lumbriculus variegatus by confining them to a quasi-2D circular chamber with a narrow exit passage. The worms move by performing undulatory and peristaltic strokes and use their head to actively probe their surroundings. We show that the worms follow the chamber boundary with occasional reversals in direction and with velocities determined by the orientation angle of the body with respect to the boundary. The average time needed to reach the passage decreases with its width before approaching a constant, consistent with a boundary-following search strategy. We model the search dynamics as a persistent random walk along the boundary and demonstrate that the head increasingly skips over the passage entrance for smaller passage widths due to body undulations. The simulations capture the observed exponential time-distributions taken to reach the exit and their mean as a function of width when starting from random locations. Even after the head penetrates the passage entrance, we find that the worm does not always escape because the head withdraws rhythmically back into the chamber over distances set by the dual stroke amplitudes. Our study highlights the importance of boundary following and body strokes in determining how active matter escapes from enclosed spaces.
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- Award ID(s):
- 1805398
- PAR ID:
- 10465725
- Date Published:
- Journal Name:
- Soft Matter
- Volume:
- 19
- Issue:
- 23
- ISSN:
- 1744-683X
- Page Range / eLocation ID:
- 4376 to 4384
- Format(s):
- Medium: X
- Sponsoring Org:
- National Science Foundation
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- Free Publicly Accessible Full Text
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Accepted Manuscript1.0
- Journal Article:
- https://doi.org/10.1039/D3SM00211J
