We report the numerical evidence of a new state of bacterial turbulence in confined domains. By means of extensive numerical simulations of the Toner-Tu-Swift-Hohenberg model for dense bacterial suspensions in circular geometry, we discover the formation a stable, ordered state in which the angular momentum symmetry is broken. This is achieved by self-organization of a turbulent-like flow into a single, giant vortex of the size of the domain. The giant vortex is surrounded by an annular region close to the boundary, characterized by small-scale, radial vorticity streaks. The average radial velocity profile of the vortex is found to be in agreement with a simple analytical prediction. We also provide an estimate of the temporal and spatial scales of a suitable experimental setup comparable with our numerical findings.
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http://dx.doi.org/10.1103/PhysRevE.106.055103 | DOI Listing |
Phys Rev Lett
December 2024
Department of Physics and Astronomy, University of Rochester, Rochester, New York 14627, USA.
Adv Mater
December 2024
College of Materials Science and Engineering, Nanjing University of Science and Technology, Nanjing, 210094, China.
Colloidal quantum dots (QDs) are attractive gain materials owing to the wide range of accessible colors. However, the existing QD lasers struggle to combine technologically relevant metrics of low threshold and long operating duration with considerable output powers. Here a new class of full-color QD lasers are reported, featuring low threshold, uninterrupted operation for dozens of hours, and multimilliwatt output under quasi-steady-state pumping, by coupling the high-gain QDs with a double-clad pumping scheme.
View Article and Find Full Text PDFPhys Rev E
July 2024
Department of Physics, Emory University, Atlanta, Georgia 30322, USA.
Flocking behavior is observed in biological systems from the cellular to superorganismal length scales, and the mechanisms and purposes of this behavior are objects of intense interest. In this paper, we study the collective dynamics of bovine sperm cells in a viscoelastic fluid. These cells appear not to spontaneously flock, but transition into a long-lived flocking phase after being exposed to a transient ordering pulse of fluid flow.
View Article and Find Full Text PDFFront Sports Act Living
July 2024
Independent Researcher, Switzerland.
The article focuses on an overview of the history, politics and cultural identity of Oldham Athletic AFC between 1960 and 2023. During this period the club, a founding member of the Football League, played across six divisions of the game's pyramid. My hometown club, the Latics faced an existential threat to its survival following relegation to the National League in 2022, before being rescued and brought back into local ownership on the long road back to its recapturing its former status.
View Article and Find Full Text PDFNature
April 2024
School of Mathematical Sciences, University of Nottingham, Nottingham, UK.
Gravity simulators are laboratory systems in which small excitations such as sound or surface waves behave as fields propagating on a curved spacetime geometry. The analogy between gravity and fluids requires vanishing viscosity, a feature naturally realized in superfluids such as liquid helium or cold atomic clouds. Such systems have been successful in verifying key predictions of quantum field theory in curved spacetime.
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