The Mixed-Gen on-line series is aimed mainly at PhD students and researchers in their first post-doc. Our goal is to continue providing a venue for these young scientists to share their work, get expert feedback and have an opportunity to strengthen scientific relations within the CECAM community and beyond.

Sessions consist of two parts. In the first, publicly available on Zoom, an experienced speaker and two/three young scientists present talks. In the second, accessible only to registered participants, posters are presented in a GatherTown room.

More detailed information on the program will appear on this page closer to the date of the event.

Links for the session:

To register use the Participate tab on this page

If you do not have a CECAM account register by clicking here...and welcome to CECAM!

Submission of posters

(Please note that - at least for the time being - we shall accept posters only from PhD students or researchers in their first two post-docs)

Register for the session as described above.

After your application is accepted, you will be able to submit a poster. In the CECAM page for this event, go to “My participation” tab and click on “Add a poster”, providing title and abstract following the recommended format. On the same form you can upload your poster file in png or jpg as soon as it is ready. These formats are strict to enable showing of the poster in the Gather session. If the poster file is not ready at the moment of submitting your abstract, you can upload it later by editing your submission (Go to “My participation” tab and click three vertical dots on “Actions” column on table “My posters”). Please upload your poster as soon as possible to enable a decision from the selection committee - see below.

Please note that posters will be visible in the Gather room associated with this session until the end of the series (June 2023) unless otherwise requested.

DEADLINE FOR SUBMISSION: TEN DAYS BEFORE THE EVENT

Selection of posters

Posters will be selected by the event organisers with the support of our main speaker and experts who will take part in the poster session. 

Selection of the talks by PhD or first year postdocs

These contributions, to be broadcasted in the Zoom webinar in the first part of the event, will be selected, after a preliminary screening by the organisers, the main speaker and guest experts, from the posters selected for the Gather session. Please tick “No” to the question “Upgrade to talk?” in your application if you DO NOT WANT your poster to be considered for upgrade to a talk. 

THE DECISION ON THE POSTER AND THE OUTCOME OF THE SELECTION OF THE TALKS WILL BE COMMUNICATED AT THE LATEST FOUR DAYS BEFORE THE EVENT

POSTER SUBMISSIONS BEYOND THIS DEADLINE WILL BE ACCEPTED BUT NOT CONSIDERED FOR UPGRADE TO TALK. SUBMISSION WILL BE DEFINITELY CLOSED FOUR DAYS BEFORE THE EVENT.

SESSION 6. Title and abstract of talks

Nonequilibrium molecular simulation: predicting results when theories don’t exist

Debra Bernhardt , The University of Queensland

The world around us in a nonequilibrium state, and although nonequilibrium statistical mechanics has seen some advances over the past decades, there are many problems that are still intractable.  Problems become particularly difficult when a system is inhomogeneous and evolving in time, but even for nonequilibrium steady state systems predictive theories are not always available.  An example is the determination of viscosities of complex non-Newtonian fluids undergoing shear flow.  Nonequilibrium molecular dynamics simulations give us a way of predicting properties and understanding what happens at the molecular level in cases where theories currently do not exist – and in some cases this can lead to new theories.  They might also provide equilibrium properties when the equilibrium state is not readily accessible or numerical errors are too high at equilibrium.  In this talk I will discuss how deterministic nonequilibrium molecular dynamics simulations can be used to model a range of systems and highlight some of the technical issues that need to be considered in carrying out this type of simulation.

Universal relation between entropy and kinetics

Benjamin Sorkin, Tel Aviv University

The theory of equilibrium thermodynamics is well established and key to the characterization of material properties. Out of equilibrium, for example in the presence of driving or activity, materials are routinely characterized by kinetic properties such as conductivities and diffusion coefficients, while thermodynamic quantities may be ill-defined or difficult to estimate. Relating thermodynamic quantities to kinetic ones is therefore a conceptual challenge with many practical benefits. Based on first principles, we derive a rigorous inequality relating the entropy of a material to the diffusion coefficient of its constituents. We do so by comparing two equivalent pictures — distinguishable particles undergoing diffusion, and indistinguishable particles that mix and approach steady state faster. The relation is universal and applicable to equilibrium as well as nonequilibrium systems. It can be used to obtain bounds for the diffusion coefficient (normal or anomalous) from the calculated thermodynamic entropy or, conversely, to estimate the entropy based on measured diffusion coefficients. We demonstrate the validity and usefulness of the relation through several examples.

Reference

[1]B. Sorkin, H. Diamant and G. Ariel, ArXiv 2212.12746 (2022)

Active turbulence and topological defects in nematic liquid crystals

Pasquale Digregorio, University of Barcelona

Active materials are systems of many particles where single constituents consume energy from the environment and convert it into mechanical work. Active matter models are inspired by macroscopic living systems and biology, and their study is primarily aimed towards a theoretical understanding of collective phenomena like flocking, clustering and other types of self-organisation.

Within a living cell, motor proteins like kinesin are responsible for the transport of intracellular components. The functioning of this active transport is well known and it has been employed to build synthetic assemblies of microtubules, which are stirred at the level of the single components and evolve out of thermal equilibrium. The presence of molecular motors drives chaotic flow at the large scale, which resembles inertial turbulence and is therefore called active turbulence.

We use a model of nematic liquid crystals in the presence of a microscopic active stress to study this system. The onset of active chaotic flows leads to a sustained proliferation of topological defects that retain some unique properties compared with passive liquid crystals. We analyse the morphology and dynamics of these topological defects to deduce fundamental properties of active turbulence.