arXiv subjects

Tanniemola Liverpool

Publications and source records attributed to Tanniemola Liverpool.

3 recordsLinked to original sources

arXiv2024

Controlling wall particle interactions with activity

We calculate the effective forces on hard disks near walls embedded inside active nematic liquid crystals. When the disks are sufficiently close to the wall and the flows are sufficiently slow, we can obtain exact expressions for the effective forces. We find these forces and the dynamics of disks near the wall depend both on the properties of the active nematic and on the anchoring conditions on the disks and the wall. Our results show that the presence of active stresses attract planar anchored disks to walls if the activity is extensile, and repel them if contractile. For normal anchored disks the reverse is true; they are attracted in contractile systems, and repelled in extensile ones.

cond-mat.soft↗

arXiv2022

Fluctuations of cell geometry and their non-equilibrium thermodynamics in living epithelial tissue

We measure different contributions to entropy production in a living functional epithelial tissue. We do this by extracting the functional dynamics of development while at the same time quantifying fluctuations. Using the translucent Drosophila melanogaster pupal epithelium as an ideal tissue for high resolution live imaging [1], we measure the entropy associated with the stochastic geometry of cells in the epithelium. This is done using a detailed analysis of the dynamics of the shape and orientation of individual cells which enables separation of local and global aspects of the tissue behaviour. We find intriguingly that we can observe irreversible dynamics in the cell geometries but without a change in the entropy associated with those degrees of freedom, showing that there is a flow of energy into those degrees of freedom. Hence the living system is controlling how the entropy is being produced and partitioned into its different parts.

cond-mat.soft↗

arXiv2020

Steady state running rate sets the speed and accuracy of accumulation of swimming bacterial populations

We study the chemotaxis of a population of genetically identical swimming bacteria undergoing run and tumble dynamics driven by stochastic switching between clockwise and counterclockwise rotation of the flagellar rotary system. Understanding chemotaxis quantitatively requires that one links the switching rate of the rotary system in a gradient of chemoattractant/repellant to experimental measures of the efficiency of a population of bacteria in moving up/down the gradient. Here we achieve this by using a probabilistic model and show that the response of a population to the gradient is complex. We find the changes to a phenotype (the steady state switching rate in the absence of gradients) affects the average speed of the response as well as the width of the distribution and both must be taken into account to optimise the overall response of the population in complex environments. This is due to the behaviour of individuals in the 'tails' of the distribution. Hence we show that for chemotaxis, the behaviour of atypical individuals can have a significant impact on the fitness of a population.

q-bio.CB↗