Monday, 09 March 2020
Time Speaker Title Resources
10:00 to 11:30 Christian Maes Mesoscopic aspects of classical transport
12:00 to 13:00 Pramod Pullarkat Physics of biological membranes

In my first lecture I’ll cover physical properties of membranes like self-assembly, elasticity, thermal fluctuations, and budding transitions. If time permits I’ll also discuss analogy between membrane dynamics and dynamics of semi-flexible polymers.

14:30 to 16:00 Julien Tailleur Motility-regulation and (self-)organization in Active Matter (Remote talk)
16:30 to 17:30 Samriddhi Sankar Ray Turbulent transport: Beyond the spherical particle approach
Tuesday, 10 March 2020
Time Speaker Title Resources
10:00 to 11:30 Christian Maes Nonequilibrium response theory
12:00 to 13:00 Pramod Pullarkat Mechanical responses of axons
14:30 to 15:30 Matthias Krüger A Non-equilibrium Bath in Theory and Experiment (Remote talk)
15:30 to 16:00 Navaneetha Krishnan Ravichandran Mode-resolved phonon scattering spectroscopy: Theory and experiments

Quantized lattice vibrations called phonons are the primary heat carriers in semiconductors and certain metals. Mathematically, phonons are defined as the eigenmodesof an idealized crystal lattice with perfectly harmonic potential, and so, can propagate through the crystal without damping when a non-equilibrium distribution of phonons is established. Weak perturbative anharmonicities and defects/boundaries/imperfections in real crystals, however, cause damping of these phonon modes through phonon-phonon and phonon-defect scattering respectively. While first principles computational techniques have enabled accurate descriptions of some of the scattering processes that the phonon modes undergo [1-3], it has been challenging to extract any scattering-related information experimentally, due to the difficulties in exciting individual phonon modes in a non-equilibrium thermal experiment. In this talk, I will describe the theory and implementation of our recent work on the mode-resolved phonon scattering spectroscopy using the transient grating experiment, that enables the extraction of microscopic phonon scattering information, such as phonon mean free paths, directly from a thermal experiment. I will also show some results on the mode-resolved surface scattering rates of phonons in silicon nanofilms extracted using this technique [4].
References:
[1] K. Chen*, B. Song*, N. Ravichandran* et al., Science 367(6477), 2020. [*: Equal contribution]
[2] N. Ravichandran & D. Broido, Nature Communications, 10(827), 2019
[3] F. Tian, B. Song, X. Chen, N. Ravichandran et al., Science 361(6402), 2018
[4] N. Ravichandran, H. Zhang & A. Minnich, Phys. Rev. X, 8(4), 041004, 2018

16:30 to 17:30 Enrico Carlon Universal Properties of Transition Path Times Statistics (Remote talk)
Wednesday, 11 March 2020
Time Speaker Title Resources
10:00 to 11:30 Christian Maes Nonequilibrium response theory - Part II
12:00 to 13:00 -- Discussion
14:30 to 16:00 -- Discussion
Thursday, 12 March 2020
Time Speaker Title Resources
10:00 to 11:30 Christian Maes Statistical forces and pattern formation
12:00 to 12:20 Arghya Das Spatial structure and relaxation in a pair of run and tumble particles

We study the static and dynamic properties of the gap between two run and tumble particles (RTPs) interacting through hardcore repulsion and moving in one dimension in the presence of translational diffusion. We calculate exact gap distribution in the steady state on a ring and find that this is exponentially localised in space, in contrast to the `jammed' configuration emerging in the absence of thermal noise. We also study the relaxation which is an exponential, characterised by a time scale which undergoes a crossover from a system size independent value to a size dependent form. For large systems, the relaxation time increases as the square of the system size. Using the symmetries in the problem we analytically study the full spectrum of the time evolution operator and characterise the transient properties of the gap distribution. On infinite line the system does not have a steady state. The long time behaviour on the infinite line is exactly computed which resembles the gap distribution between interacting passive particles, except a signature of activity for small gap.

12:20 to 12:40 Subhadip Chakraborti Hydrodynamics, superfluidity and giant number fluctuations in a model of self-propelled particles

We derive hydrodynamics of a prototypical one dimensional model, having variable-range hopping, which mimics passive diffusion and ballistic motion of active, or self-propelled, particles. The model has two main ingredients - the hardcore interaction and the competing mechanisms of short and long range hopping. We calculate two density-dependent transport coefficients - the bulk-diffusion coefficient and the conductivity, the ratio of which, despite violation of detailed balance, is connected to number fluctuation by an Einstein relation. In the limit of infinite range hopping, the model exhibits, upon tuning density ρ and activity  ̃q, a “superfluid” transition from a disordered homogeneous phase to an inhomogeneous “ordered” phase of coexisting bulk superfluid and a vacancy “condensate”. The superfluid is characterized by a diverging conductivity, which greatly increases particle (or vacancy) mobility and induces “giant” number fluctuations in the system.

12:40 to 13:00 Pritha Dolai Universality in single file diffusion of active particles

We study the single-file dynamics of three classes of active particles: run-and-tumble particles, active Brownian particles and active Ornstein-Uhlenbeck particles. At high activity values, the particles, interacting via purely repulsive forces, aggregate into several motile and dynamical clusters of comparable size. We find that the cluster size distribution of these aggregates is a scaled function of the density and activity parameters across the three models of active particles with the same scaling function. The velocity distribution function of these mobile clusters is non-Gaussian. We show that the effective dynamics of these clusters can explain the observed emergent scaling of the mean-squared displacement of tagged particles for all the three models with identical scaling exponents and functions. Concomitant with the clustering seen at high activities, we observe that the static density correlation function displays rich structures, including several peaks in the static two-point function, reminiscent of particle clustering induced by effective attractive interactions, while the dynamical variant shows non-diffusive scaling. Our study reveals a universal scaling behavior in the single-file dynamics of strongly interacting active particles.

14:30 to 16:00 -- Poster
16:30 to 17:30 Christopher Jarzynski Classical fluctuation theorems (Remote talk)

Brief review of relevant macroscopic thermodynamics.
Introduction to and derivations of nonequilibrium work relations.
Connections to 2nd Law: probabilities of observing "violations".
Guessing the direction of Time's Arrow.
Discussion of fluctuation theorems for entropy production.

Friday, 13 March 2020
Time Speaker Title Resources
10:00 to 11:30 Christian Maes Large deviations in Nonequilibrium
12:00 to 13:00 Ranjini Bandyopadhyay Activity-induced fluidization of a jammed suspension of bidisperse colloidal spheres
14:30 to 16:00 Julien Tailleur On the anomalous thermomechanics of dry active matter (Remote talk)
16:30 to 17:30 Satya N Majumdar Persistence and first-passage properties of stochastic processes
Monday, 16 March 2020
Time Speaker Title Resources
10:00 to 11:00 Satya N Majumdar Universal survival probability of a run and tumble particle in d dimensions.
11:30 to 12:30 Abhishek Dhar Active Brownian particles: mapping to equilibrium polymers and exact computation of moments

I will discuss (i) an exact mapping  between  trajectories of Active Brownian Particles (ABP) and various polymer configuration and (ii) an exact method of computing all moments, of both positional and orientational degrees of freedom of free and harmonically trapped ABPs. Some applications will be discussed.

14:30 to 14:50 Ion Santra RTP IN 2 DIMENSIONS

We study a set of RTP in 2 spatial dimensions, where the orientation of the particle can change by discrete or continuous values. We calculate the position distributions and show the transition from short time active to long time passive limit.

14:50 to 15:10 Prashant Singh Run and tumble particle in inhomogeneous media

I will talk about run and tumble dynamics in inhomogeneous medium in one dimension. The run and tumble dynamics is a simple model that mimics bacterial chemotaxis. The dynamics in  homogenous medium is known to become diffusive at large times. Question is what happens in inhomogeneous medium? Presenting a toy model, I will show that the fluctuations become non-diffusive at large time and the distribution obeys a scaling form which can be exactly computed. I will also discuss about the first-passage properties and persistent exponents for the toy model.

15:10 to 15:30 Santanu Das Statistics of overtake events by a self-driven tagged agent
16:00 to 17:30 Edgar Roldán Non-equilibrium signals of life (Remote talk)

First I will review theoretical and experimental efforts to characterize sources of irreversibility and dissipation in living systems from measurements of few fluctuating variables. Special emphasis will be given to the case of active mechanosensory hair bundles in the ear of the bullfrog. 

Tuesday, 17 March 2020
Time Speaker Title Resources
10:00 to 11:00 Simone Pigolotti Error-speed correlations in biopolymer synthesis (Remote talk)
11:30 to 12:30 Sanjib Sabhapandit Barrier-crossing rate via the full First-passage probability distribution
14:30 to 15:30 Sayantan Majumdar Yielding in a dense suspension of adhesive amorphous particles
16:00 to 17:30 Edgar Roldán Stochastic resetting by RNA polymerases fromtranscriptional pauses (Remote talk)

The second lecture will discuss fluctuations of RNA polymerases during transcription. I will present minimal models that describe recovery from transcriptional pauses using stochastic resetting and their application to experimental data.

Thursday, 19 March 2020
Time Speaker Title Resources
10:00 to 11:00 Sashi Thutupalli TBA
11:30 to 12:30 Vijaykumar Krishnamurthy TBA
14:30 to 15:00 Hari Kumar Yadalam Statistics of energy transport across squeezed thermal baths
15:00 to 15:30 Vinu Varghese Pulikkottil Mathematical modeling of stimulus driven dendritic spine formation
16:00 to 17:30 Edgar Roldán Extreme-value statistics of biological transport phenomena: insights from martingales and random matrices (Remote talk)

The third lecture will be focused on  extreme-value statistics of biological processes, presenting exact solutions for extreme excursions of molecular motors and their associated entropy production. This lecture will conclude with a swift appetizer on the usage of martingales and random matrix theory to tackle extreme-value statistics.