News from Bio and Nano Physics

  09.11.2022 Our paper "Resonant diffusion of a gravitactic circle swimmer" has been accepted for publication in Physical Review Letters! (Link)

To describe motion of swimming microorganisms microswimmer models have been employed with great success over the last years. They allow to describe the non-trivial behavior of motile organisms, such as bacteria, sperm cells, and amoebae.

In our paper we discover-using computer simulations and numerical methods-resonance of spatial diffusivity of a microwswimmer subject to external force field, such as gravity. The torque arising from gravitational interaction can cancel out own rotation frequency of a circle swimmer leading to almost unlimited growth of fluctuations. To obtain analytical-numerical solution we used operator-based methods developed in quantum mechanics.

The results of our research will have implications for any active matter system moving under an influence of an external field-gravitaxis, chemotaxis, rheotaxis, etc. Our findings can serve as a guide for experiments in the field of active particles.

 Oleksandr_and_Thomas_PRL2022

  30.09.2022 Our paper "Analytic Solution of an Active Brownian Particle in a Harmonic Well" has been published in Physical Review Letters! (Link)

Active matter and directed motion are central topics in several research fields, including biology, biomedicine, and robotics.
However, exactly solvable problems in active matter are rare.

In our paper, we borrow from quantum mechanics concepts such as the quantization of spin and angular momentum and methods such as perturbation theory to tackle the problem of how an active Brownian particle behaves in a harmonic potential.

By using the passive Brownian particle as a reference system and dealing with the activity as a perturbation, we find exact analytical expressions for the probability distribution in a harmonic potential of an active Brownian particle conditioned to some initial conditions.
Our solution also allows to derive paradigmatic moments, correlation functions and the time-dependent diffusion coefficient.

ABP_HWell_graphical_abstract

 See also https://arxiv.org/abs/2210.04205 for open version. 

  19.-22.09.2022 Group retreat at Bartholomäberg with Soft Matter Theory group from Universität Konstanz

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 group retreat_2
Hiking event Talks and discussions

  08.09.2022, Invited speaker: Talk by T. Franosch, Venice meeting on Fluctuations in small complex systems VI, Title: Gravitaxis of a single active Brownian particle


  07.09.2022Emerging talents: Talk by M. Caraglio and A. Squarcini, Venice meeting on Fluctuations in small complex systems VI,Title: Active Brownian particle in a harmonic well and Several exact results on statistics of single-trajectory spectral densities of stochastic processes beyond their mean values


  14.07.2022, At its Board of Trustees meeting on 27 June 2022, the FWF approved numerous projects by researchers at the University of Innsbruck, also 2 of our research group:

Michele Caraglio (Stand alone project), "Target-Search Strategies of Smart Active Agents"

Thomas Franosch (Stand alone project), "Time-dependent nonlinear shear response in dilute Brownian suspensions"


  28.06.2022, 17:15 Innsbruck Physics Colloquium "Beyond Brownian Motion: From Data to Models", Speaker: Ralf Metzler, Universität Potsdam | Location: lecture hall A


Metzler
Group hike to Gasthof Rauschbrunnen with our guest Prof. Ralf Metzler. 

  21.06.2022, Masterdefensio of Francesco Di Trapani "First Passage Times of Active Brownian Particles" , 13:00, HSB 8


  25.05.2022, 16:15 "Theory Colloquium: Microscopic chaos, fractals and transport in nonequilibrium statistical mechanics"      Speaker: Rainer Klages, Queen Mary University of London, School of Mathematical Sciences | Location: SR 1, ICT building


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Group hike to Höttinger Alm with our guest Prof. Rainer Klages.

day of physics


LNF

 
On #DayofPhysics and #LongNightofResearch the group demonstrated soft matter, Target search of active agents (via Hexbug maze) and computer simulations to the student community and the general public. The main attraction among students and the general public was" Target search of active agents".
 

  05.05.2022 Invited Talk T. Franosch, ICTP Hybrid meeting on "Non-Markovian Dynamics Far From Equilibrium", Title: "Persistent correlations in dilute Brownian suspensions in equilibrium and their fate upon strong driving", link to the video on You Tube

  02.05.2022 PhD final examination of Luigi Zanovello, Title: "Target search of active particles in comlex environments",   Supervisor: Prof. Pietro Faccioli, Prof. Thomas Franosch

Defensio_LZanovello


  14.03.2022, At its Board of Trustees meeting on 07 March 2022, the FWF approved numerous projects by researchers at the University of Innsbruck, also 1 of our research group:

Thomas Franosch (Stand alone project), "Target Search of Single Active Brownian Particles"


  15.10.2022, At its Board of Trustees meeting on 27 September 2021, the FWF approved numerous projects by researchers at the University of Innsbruck, also 1 of our research group:
 
Alessio Squarcini (Lise Meitner project), "Driven lattice Lorentz gases in confinement"

   8.01.2020 Our paper "Target search of active agents crossing high energy barriers" has been published in Physical Review Letters!  (Link)

Many research fields in biology, medicine, and pharmacology involve active agents exploring complex environments in order to reach a target region.

Whenever searching involves overcoming energy barriers, naive computer simulations may become inefficient, while advanced methods specific for a rare transition cannot be straightforwardly applied because of the non-equilibrium character of active agents.

In our paper, we solve this problem by developing an algorithm generalizing Transition Path Sampling (a renowned algorithm for enhanced sampling) to active Brownian dynamics.

PRL_target-search

 


  23.9.2020 Our new paper on  active crowded needles has been published! 


 23.6.2020 Group hike to Höttinger Alm with the students of the computational physics class.

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  27.4.2019 The group demonstrated soft matter, active particles and computer simulations to the public at the University of Innsbruck campus open day. The silly putty and soap propelled boats were a big hit with the kids!
open_day2

open_day

 

   10.4.2019 Prof. Dr. Felix Höfling from the Freie Universität Berlin presents his work on "Emergence of molecular friction in liquids: a memory kernel perspective" at the theory colloquium.

 

  16.8.2018 Our new paper on the dynamics of catalytic Janus particles has been published! 

  • C Kurzthaler, C Devailly, J Arlt, T Franosch, WCK Poon, VA Martinez, AT Brown, Probing the spatiotemporal dynamics of catalytic Janus colloids with single-particle tracking and differential dynamic microscopyPhys. Rev. Lett. 121 (7), 078001 (2018) 

See Newsroom for more info. 

outreach_janus(credit: AT Brown, University of Edinburgh)

 


 23.7.2018 Group retreat in Gaschurn with the Soft Matter Theory group from Universität Konstanz.


Group retreat 2018

  15.6.2018 Hiking day with the ITP!


  13.6.2018 Prof. Dr. Martin Oettel from the University of Tuebingen presents his work on 'Small particles at fluid interfaces: model systems for 2d gravity, the Casimir effect and anomalously fast diffusion' at the Theory colloquium (17.15h,   2S17, 1st floor, ITP)


  22.5.2018 Luca Pizzagalli from the University of Trento joins us for his master project


 

Past events

CMD26 – The 26th Conference of the Condensed Matter Division of the EPS

conference logo groningen

Groningen (Netherlands), September 4-9, 2016

The 26th Conference of the Condensed Matter Division will encompass all areas of Condensed Matter Physics, from soft matter and biophysics to correlated electron systems and quantum simulators. CMD 26 follows on the success of CMD 24 in Edinburgh in 2012 and CMD 25 / Condensed Matter in Paris in 2014, and turnout is expected to be large. Please visit the conference website at http://cmd26.eu/home/ .

3rd International Workshop – Nonlinear Response in Complex Matter 

Primošten (Croatia), September 26-30, 2016

This workshop features lectures dealing with the nonlinear response of complex systems upon application of external perturbations, with contributions from groups dealing with experiment, computer simulation and theory. Examples are the response in strong external fields, non-linear rheology of dense complex fluids, plastic events in amorphous solids, or granular materials.

conference logo croatia

It is part of a series of workshops with this title and is sponsored by the DFG-Research Unit FOR 1394 “Nonlinear response to probe vitrification”. The last workshop took place in Erlangen in 2013. Complex systems are characterized by many degrees of freedom with competing interaction. For understanding the highly complex dynamics it is extremely helpful to go beyond the linear response. A detailed characterization of the spatio-temporal nonlinear response to homogeneous and inhomogeneous perturbations contains important additional pieces of information about the underlying structural and dynamical properties. In macro-rheological experiments this amounts, e.g., to the understanding of shear thinning, shear thickening or the occurrence of shear bands. However, the full scope of the nonlinear response and the corresponding non-equilibrium behavior has yet to be fully explored.

This workshop will be a platform for discussions on recent developments in this active and multi-disciplinary field. By bringing together workers from these different fields, a fruitful exchange about the similar behaviors but also the differences, ranging from microscopic to macroscopic length scales, is envisaged.

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Organisation

Scientific: Andreas Heuer
(Universität Münster)

Financial: Matthias Fuchs
(Universität Konstanz)

Local: Thomas Franosch, David Smith
(Universität Innsbruck, RBI Zagreb)

Web/Technical: Markus Blank-Burian
(Universität Münster)

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