News from Bio and Nano Physics
22.01.2024 Our Paper "Characterization and Control of the Run-and-Tumble Dynamics of Escherichia Coli " has been published in Physical Review Letters! (Link)
Forscher:innen der AG Franosch und die Tiroler Wissenschaftlerin Christina Kurzthaler haben gemeinsam mit einem internationalen Team die Bewegungsmuster des Bakteriums Escherichia coli beschrieben. Dafür nutzten sie einen genmodifizierten Bakterienstamm, Experimente unter dem Mikroskop und komplizierte Funktionen.
Der Vergleich von Experimenten und Theorie durch eine intermediäre Streufunktion ist die Leistung von Christina Kurzthaler. Diese Arbeit begann im Rahmen ihrer Doktorarbeit in der Forschungsgruppe von Thomas Franosch. Kurzthaler ist eine der Erstautorinnen der Studie und leitet heute eine eigene Arbeitsgruppe am Max-Planck-Institut für Physik komplexer Systeme in Dresden.
Die Arbeit wurde gerade als Editor’s Pick in Physical Review Letters veröffentlicht, einer der wichtigsten Fachzeitschriften der Physik.
Publikation: Characterization and Control of the Run-and-Tumble Dynamics of Escherichia Coli. Christina Kurzthaler, Yongfeng Zhao, Nan Zhou, Jana Schwarz-Linek, Clemence Devailly, Jochen Arlt, Jian-Dong Huang, Wilson C. K. Poon, Thomas Franosch, Julien Tailleur, Vincent A. Martinez. Phys. Rev. Lett. 132, 038302, DOI: 10.1103/PhysRevLett.132.038302
09.11.2023, Masterdefensio of Thomas Kiechl, "Advanced Sampling Methods for Non-Equilibrium Particles", 10:00, SR 1
24.-26.07.2023 Group and colleagues at a retreat in Bartholomäberg, Austria, in July 2023
19.04.2023 Our paper "Thermophoretic motion of a charged single colloidal particle" has been published in Physical Review E! (Link)
19.04.2023 Our paper "Thermophoresis beyond Local Thermodynamic Equilibrium" has been published in Physical Review Letters! (Link)
The directed drift motion of colloidal particles and molecules along a temperature gradient has
been known for more than 150 years in aqueous solutions. This effect, referred to as thermophoresis constitutes an essential transport mechanism in numerous natural and technical processes.
However, it is still debated, whether thermophoresis obeys a description within reversible thermodynamics by assuming a local thermodynamic equilibration of the system or it turns out to be a transport process of purely non-equilibrium nature.
In our paper, we address this question by measuring the thermophoretic velocity of polystyrene beads of variable radii immersed in an electrolyte solution with different salt concentrations.
For sufficiently high thermal gradients, characterized by a thermal Péclet number Pe larger than one, a pronounced nonlinear behavior in the rescaled drift velocity emerges thereby constituting first experimental corroboration for thermophoretic motion beyond local thermodynamic equilibrium. The corresponding decay in the amplitude of the velocity is in accordance with our hydrodynamic model for thermophoresis.
Furthermore, the obtained data collapse for all radii and salt concentrations suggests also an underlying universal mechanism for the crossover into a genuinely nonlinear regime.
22.03.2023, 16:15 "Theory Colloquium: Coarse-Graining Non-Equilibrium Soft Matter Systems" , Speaker: Gerhard Jung, Universite de Montpellier, France | Location: SR 1, ICT building
09.11.2022 Our paper "Resonant diffusion of a gravitactic circle swimmer" has been accepted for publication in Physical Review Letters! (Link)
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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. |
30.09.2022 Our paper "Analytic Solution of an Active Brownian Particle in a Harmonic Well" has been published in Physical Review Letters! (Link)
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Active matter and directed motion are central topics in several research fields, including biology, biomedicine, and robotics. 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.
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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| 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
07.09.2022, Emerging 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"
28.06.2022, 17:15 Innsbruck Physics Colloquium "Beyond Brownian Motion: From Data to Models", Speaker: Ralf Metzler, Universität Potsdam | Location: lecture hall A
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
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
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"
8.01.2020 Our paper "Target search of active agents crossing high energy barriers" has been published in Physical Review Letters! (Link)
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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. |
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23.9.2020 Our new paper on active crowded needles has been published!
- S Mandal, C Kurzthaler,T Franosch, H Löwen, Crowding-enhanced diffusion: An exact Theory for Highly Entangled Self-Propelled Stiff Filaments, Physical Review Letters 125, 138002 (2020)
see also Physics News article by Rachel Berkowitz
23.6.2020 Group hike to Höttinger Alm with the students of the computational physics class.
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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 microscopy, Phys. Rev. Lett. 121 (7), 078001 (2018)
See Newsroom for more info.
23.7.2018 Group retreat in Gaschurn with the Soft Matter Theory group from Universität Konstanz.
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
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.
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.
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)