The viscosity of a suspension swimming bacteria is investigated analytically and numerically. We propose simple model that allows for efficient computation large number bacteria. Our calculations show long-range hydrodynamic interactions, intrinsic to self-locomoting objects in viscous fluid, result dramatic reduction the effective viscosity. In agreement with experiments on suspensions Bacillus subtilis, we related onset large-scale collective motion due interactions between swimmers....

The study of collective motion in bacterial suspensions has been significant recent interest. To better understand the non-trivial spatio-temporal correlations emerging course swimming motile bacteria, a simple model is employed: bacterium represented as force dipole with size, through use short-range repelling potential, and shape. emphasizes two fundamental mechanisms: dipolar hydrodynamic interactions collisions. Using direct particle simulations validated by dedicated experiment, we show...

The physical properties of collectively swimming bacteria have been thoroughly investigated both experimentally and theoretically using simulations. While models successfully predict some aspects the dynamics observed in experiments, experiments vary their underlying assumptions conditions. Hence, it is not clear which are appropriate for experimental setups. Here, we study, two types (agent-based continuous), statistics strains Serratia marcescens, wild-type a nontumbling strain, on...

While the total cover of broken cloud fields can in principle be obtained from one-dimensional measurements, size distribution normally differs between two-dimensional (area) and retrieval (chord length) methods. In this study, we use output high-resolution Large Eddy Simulations to generate a transfer function two. We retrieve chord lengths areas for many clouds, plot one as other, vice versa. find that area conditional on length behaves like gamma with well-behaved parameters, mean μ=1.1L...

Heterogeneous systems of active matter exhibit a range complex emergent dynamical patterns. In particular, it is difficult to predict the properties mixed system based on its constituents. These considerations are particularly significant for understanding realistic bacterial swarms, which typically develop heterogeneities even when grown from single cell. Here, swarms cells with different aspect ratios studied both experimentally and in simulations. contrast previous theory, there no...

Suspensions of self-propelled microscopic particles, such as swimming bacteria, exhibit collective motion leading to remarkable experimentally observable macroscopic properties. Rigorous mathematical analysis this emergent behavior can provide significant insight into the mechanisms behind these experimental observations; however, there are many theoretical questions remaining unanswered. In paper, we study a coupled PDE/ODE system first introduced in physics literature and used investigate...

Glasses are rigid systems in which competing interactions prevent simultaneous minimization of local energies. This leads to frustration and highly degenerate ground states the nature properties still far from being thoroughly understood. We report an analytical approach based on method functional equations that allows us construct Rayleigh approximation state a two-dimensional (2D) random Coulomb system with logarithmic interactions. realize model for 2D glass as cylindrical type II...

Abstract The causes of vertical cloud overlap, the ratio between fraction by area and volume, are studied for fields cumulus convection. Using large‐eddy simulations, structure individual clouds within field is inspected connected to overall cover entire field. First, it shown that overlap can be well approximated total clouds. It then a simple maximum assumption, which commonly used with small layer depth, only account roughly half inefficiency. This due fact represents variations in width...

During meiosis, pairing of homologous chromosomes (homologs) ensures the formation haploid gametes from diploid precursor cells, a prerequisite for sexual reproduction. Pairing during meiotic prophase I facilitates crossover recombination and homolog segregation ensuing reductional cell division. Mechanisms that ensure stable alignment in presence an excess non-homologous have remained elusive, but rapid chromosome movements appear to play role process. Apart attraction, provided by early...

How bacteria sense local chemical gradients and decide to move has been a fascinating area of recent study. Chemotaxis bacterial populations traditionally modeled using either individual-based models describing the motion single bacterium as velocity jump process, or macroscopic PDE that describe evolution density. In these models, hydrodynamic interaction between is usually ignored. However, shown induce collective self-organization resulting in larger mesoscale structures. this paper, role...

Active colloidal particles regularly interact with surfaces in applications ranging from microfluidics to sensing. Recent work has revealed the complex nature of these surface interactions for active particles. Herein, we summarize experiments and simulations that show impact charged nanoparticles on propulsion an colloid near a boundary. Adding not only decreased average separation distance passive because depletion attraction as expected but also apparent Janus zero. Complementary...

The von Neumann-Mullins law for the area evolution of a cell in plane describes how dry foam coarsens time. Recent theory and experiment suggest that dynamics are different on surface three-dimensional object such as sphere. This work considers foams Starting from first principles, we use computer simulation to show curvature-driven motion boundaries leads exponential growth decay areas cells, contrast planar case where is linear. We describe distribution cells final stationary state.