7th KIAS Conference on Statistical Physics
[Talk 6] Nonequilibrium response in a model for sensory adaptation
SPEAKER | Leihan Tang
INSTITUTE | Beijeihan Tang, Beijinging / HKBU
DATE | July 4(Mon), 2016
TIME | 13:00
PLACE | Korea Institute for Advanced Study (KIAS), Seoul, Korea
ABSTRACT | The ability to monitor nutrient and other environmental conditions with high sensitivity is
crucial for cell growth and survival. Sensory adaptation allows a cell to recover its sensitivity
after a transient response to a shift in the strength of extracellular stimulus. The working
principles of adaptation have been established previously based on rate equations which do not
consider fluctuations in a thermal environment. Recently, Tu and collaborators (Nature Phys.
8:422-8, 2012; Phys. Rev. Lett. 115:118, 2015) performed a detailed analysis of a stochastic
model for the E. coli sensory network. They showed that accurate adaptation is possible only
when the system operates in a nonequilibrium steady-state. They further obtained a relation
among energy dissipation, adaptation speed and adaptation error through model calculation and
suggested that it may hold generally. However, adaptation is only one aspect of the bacterial
chemo-sensing system. Its transient response to ligand concentration fluctuations with high
gain is at least as important. We present here a more refined calculation on the systemí»s
response at all frequencies. The simplicity of the model allows a rigorous treatment using
methods of statistical mechanics. The model also possesses several desirable analytic
properties which make it an attractive testing ground to demystify various general results on
energy dissipation and linear response in nonequilibrium states, including for example the link
to the Harada-Sasa equality for a discrete-state Markov system[1,2].
The work is supported in part by the NSFC under Grant No. U1430237 and by the Research
Grants Council of the Hong Kong Special Administrative Region (HKSAR) under Grant No.
 S.-W. Wang, Y. Lan and L.-H. Tang, JSTAT P07025 (2015).
 S.-W. Wang, K. Kawaguchi, S.-i. Sasa, and L.-H. Tang, arXiv:1601.04463.