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X-WR-CALNAME:Statistical Physics and Complexity Group meeting
X-WR-CALDESC:Statistical Physics and Complexity Group meeting
X-PUBLISHED-TTL:PT12H
CALSCALE:GREGORIAN
METHOD:PUBLISH
BEGIN:VTIMEZONE
TZID:Europe/London
X-LIC-LOCATION:Europe/London
BEGIN:DAYLIGHT
TZOFFSETFROM:+0000
TZOFFSETTO:+0100
DTSTART:19810329T010000
RRULE:FREQ=YEARLY;BYMONTH=3;BYDAY=-1SU
TZNAME:BST
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TZOFFSETFROM:+0100
TZOFFSETTO:+0000
DTSTART:19961027T020000
RRULE:FREQ=YEARLY;BYMONTH=10;BYDAY=-1SU
TZNAME:GMT
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END:VTIMEZONE
BEGIN:VEVENT
CLASS:PUBLIC
UID:EVENT-81582@www.ph.ed.ac.uk
DTSTAMP:20220520T182951
CREATED:20210430T101916
LAST-MODIFIED:20210522T125110
STATUS:CONFIRMED
DTSTART;TZID=Europe/London:20210526T100000
DTEND;TZID=Europe/London:20210526T110000
SUMMARY:Socio-ecology of active matter: two experiments with fish
DESCRIPTION:Understanding the collective motion of groups of animals has b
een a long-standing goal of active matter research. Classical swarming and
flocking models consider large homogeneous groups of agents governed by s
imple rules which are capable of producing startling emergent behaviours.
Looking closer\, however\, there is a disconnect between these models and
what can be observed in experiments tracking individuals within groups. In
this talk I will discuss two features – the speed of information flow\,
and differing motivations of individuals – that have been observed to h
ave profound effects on the collective motion of fish. In each case develo
ping theoretical frameworks to explain experimental observations and make
new predictions.\n\nSpeaker:\n* Professor Tim Rogers (University of Bath)
LOCATION:Online - see email.
URL:https://www.ph.ed.ac.uk/events/2021/81582-socio-ecology-of-active-matt
er-two-experiments-with-fish
END:VEVENT
BEGIN:VEVENT
CLASS:PUBLIC
UID:EVENT-81580@www.ph.ed.ac.uk
DTSTAMP:20220520T182951
CREATED:20210430T100716
LAST-MODIFIED:20210531T191427
STATUS:CONFIRMED
DTSTART;TZID=Europe/London:20210602T100000
DTEND;TZID=Europe/London:20210602T110000
SUMMARY:Self-Organized Lane Formation in Bidirectional Transport by Molecu
lar Motors
DESCRIPTION:Within cells\, vesicles and proteins are actively transported
several micrometers along the cytoskeletal filaments. The transport along
microtubules is propelled by dynein and kinesin motors\, which carry the c
argo in opposite directions. Bidirectional intracellular transport is perf
ormed with great efficiency\, even under strong confinement\, as for examp
le in the axon. For this kind of transport system\, one would expect gener
ically cluster formation. In this talk\, I'll discuss the effect of the re
cently observed self-enhanced binding-affinity along the kinesin trajector
ies on the MT. In particular\, a stochastic lattice-gas model will be int
roduced\, where the enhanced binding affinity is realized via a floor-fiel
d. From Monte Carlo simulations and a mean-field analysis we show that thi
s mechanism can lead to self-organized symmetry-breaking and lane-formatio
n which indeed leads to efficient bidirectional transport in narrow enviro
nments. \n\nRef.: R. Jose\, L. Santen: Self-Organized Lane Formation i
n Bidirectional Transport by Molecular Motors\, Phys. Rev. Lett. 124\, 1
98103 (2020).\n\nSpeaker:\n* Professor Ludger Santen (University of Saarla
nd)
LOCATION:Online - see email.
URL:https://www.ph.ed.ac.uk/events/2021/81580-self-organized-lane-formatio
n-in-bidirectional-transport-by-molecular-motors
END:VEVENT
BEGIN:VEVENT
CLASS:PUBLIC
UID:EVENT-81586@www.ph.ed.ac.uk
DTSTAMP:20220520T182951
CREATED:20210430T103210
LAST-MODIFIED:20210603T134122
STATUS:CONFIRMED
DTSTART;TZID=Europe/London:20210609T100000
DTEND;TZID=Europe/London:20210609T110000
SUMMARY:Optimal Work Extraction and the Minimum Description Length Princip
le
DESCRIPTION:We establish a connection between optimal work extraction in s
tochastic thermodynamics and efficient universal data compression\, by sho
wing that the maximal work that can be extracted in an information engine
that relies on the measurement of a quantity X equals the minimum descript
ion length complexity of the statistical model that has X as a sufficient
statistics. This provides design principles for optimal information engine
s. In particular\, it suggests that optimal coding is thermodynamically ef
ficient\, and that it is essential to drive the system into a non-equilibr
ium critical state in order to achieve optimal performance (see arXiv:2006
.04544 or Léo Touzo et al J. Stat. Mech. (2020) 093403)\n\nSpeaker:\n* Ma
tteo Marsili (The Abdus Salam International Centre for Theoretical Physics
)
LOCATION:Online - see email.
URL:https://www.ph.ed.ac.uk/events/2021/81586-optimal-work-extraction-and-
the-minimum-description-length-principle
END:VEVENT
BEGIN:VEVENT
CLASS:PUBLIC
UID:EVENT-81584@www.ph.ed.ac.uk
DTSTAMP:20220520T182951
CREATED:20210430T102328
LAST-MODIFIED:20210610T120632
STATUS:CONFIRMED
DTSTART;TZID=Europe/London:20210616T150000
DTEND;TZID=Europe/London:20210616T160000
SUMMARY:Dispersion in confined and fluctuating systems
DESCRIPTION:I will discuss some recent work on the effective transport pro
perties\, the effective diffusion constant and late time drifts\, in confi
ned systems. In particular I will address diffusion in channel like system
s which are relevant for micro-fluidic and biological systems. Geometrical
features for time independent geometries can lead to a slowing down of di
spersion due to entropic trapping effects and I will present some improvem
ents on the classic Fick-Jacobs approximation for these systems. I will al
so talk about how Taylor dispersion is modified by potential interactions
with the boundaries and variable diffusivity\, notably due to the vanishin
g of the diffusion constants at the boundaries. Finally I will examine dis
persion in systems which have geometrical fluctuations\, either generated
thermally or by driving the surfaces\, in these systems geometric fluctuat
ions can either enhance or diminish dispersion with respect to their stati
c counterparts. \n\nSpeaker:\n* Professor David Dean (University of Borde
aux)
LOCATION:Online - see email.
URL:https://www.ph.ed.ac.uk/events/2021/81584-dispersion-in-confined-and-f
luctuating-systems
END:VEVENT
BEGIN:VEVENT
CLASS:PUBLIC
UID:EVENT-81579@www.ph.ed.ac.uk
DTSTAMP:20220520T182951
CREATED:20210430T100006
LAST-MODIFIED:20210617T191827
STATUS:CONFIRMED
DTSTART;TZID=Europe/London:20210623T100000
DTEND;TZID=Europe/London:20210623T110000
SUMMARY:Gene regulatory networks versus Neural networks and Bipartite Grap
hs: what we can learn on cellular (re)programming
DESCRIPTION:Cell differentiation is one of the most fascinating areas of d
evelopmental biology. This was long thought to be an irreversible process
\, however it has been shown recently that it is possible to reprogramme
fully differentiated cells into a state which strongly resembles embryoni
c stem cells\, via the introduction of a few transcription factors. This
opens up exciting perspective\, however\, no universally accepted theory e
xists that explains the phenomena. The purpose of this work is to drive fo
rward our understanding of cell reprogramming and programming by using too
ls from statistical mechanics. \n\nIn the first part of the talk we pre
sent a model for gene expression dynamics inspired by neural networks. Cel
l types are modelled as hierarchically organized dynamical attractors of t
he gene expression dynamics and reprogramming is rationalised as triggerin
g transitions between attractors laying at different levels of the hierarc
hy. We found two mechanisms for such switching\, induced by noise and dire
ct perturbations\, which offer interesting perspectives on reprogramming e
xperiments. \n\nIn the second part of the talk\, the mechanism for the
effective interactions arising between genes\, is studied by means of a di
rected bipartite graph model\, that integrates the genome and transcriptom
e into a single regulatory network\, evolving according to the AND logic d
ynamics. By adapting percolation theory to directed bipartite graphs\, ev
olving according to the AND logic dynamics\, we are able to determine the
necessary conditions\, in the network parameter space\, under which spars
e bipartite networks can support a multiplicity of stable gene expression
patterns\, under noisy conditions\, as required in stable cell types. In p
articular\, the analysis reveals the possibility of a bi-stability region\
, where the extensive percolating cluster is or is not resilient to pertur
bations\, and it provides valuable insights for the interpretation of gene
knock-out experiments. \n\n\n [1] Percolation on the gene regulatory
\, Giuseppe Torrisi\, Reimer Kühn\, Alessia Annibale\, J. Stat. Mech. (2
020) 083501 \n\n[2] Percolation in Gene Regulatory Networks and its
role in sustaining life\, R Hannam\, R\, Kühn\, A Annibale\, J. Phys.
A: Math. Theor. 52 334002 (2019) \n\n[3] Cell reprogramming modelled
as transitions in a hierarchy of cell cycles\, R Hannam\, A Annibale\, R K
ühn J. Phys. A: Math. Theor. 50 425601 (2017)\n\nSpeaker:\n* Alessia Ann
ibale (King's College London)
LOCATION:Online - see email.
URL:https://www.ph.ed.ac.uk/events/2021/81579-gene-regulatory-networks-ver
sus-neural-networks-and-bipartite-graphs-what-we-can-learn-on-cellular
END:VEVENT
BEGIN:VEVENT
CLASS:PUBLIC
UID:EVENT-81795@www.ph.ed.ac.uk
DTSTAMP:20220520T182951
CREATED:20210909T140525
LAST-MODIFIED:20211013T155817
STATUS:CONFIRMED
DTSTART;TZID=Europe/London:20210928T150000
DTEND;TZID=Europe/London:20210928T160000
SUMMARY:Einstein's fluctuation relation and Gibbs states far from equilibr
ium
DESCRIPTION:I will present a class of one-dimensional nonequilibrium inter
acting particle models characterised by a so-called "gradient condition" w
hich generalises detailed balance and guarantees the existence of Gibbs-ty
pe local homogeneous stationary states. I will show how\, defining appropr
iate boundary conditions\, this leads to a special symmetry of the models
under time and space reversal which\, rephrased in terms of the large devi
ations function of stationary currents of conserved quantities\, yields a
novel fluctuation relation under reservoir exchange\, independent from the
standard Gallavotti-Cohen symmetry. I will then show that this relation c
an be interpreted as a nonequilibrium and nonlinear generalisation of Eins
tein's relation\, which points to the existence of a Langevin-type hydrod
ynamic equation for the macroscopic behaviour of those models.\n\nSpeaker:
\n* Alexandre Lazarescu (UCLouvain)
LOCATION:Zoom - see email invite.
URL:https://www.ph.ed.ac.uk/events/2021/81795-einsteins-fluctuation-relati
on-and-gibbs-states-far-from-equilibrium
END:VEVENT
BEGIN:VEVENT
CLASS:PUBLIC
UID:EVENT-81794@www.ph.ed.ac.uk
DTSTAMP:20220520T182951
CREATED:20210909T114612
LAST-MODIFIED:20210916T111306
STATUS:CONFIRMED
DTSTART;TZID=Europe/London:20211005T150000
DTEND;TZID=Europe/London:20211005T160000
SUMMARY:Are Confluent Cell Layers Extensile or Contractile?
DESCRIPTION:A lot is understood about the ways in which single cells move
over a surface\, but the motion of confluent layers of epithelial cells\,
which are coupled through strong intercellular junctions\, remains puzzlin
g.\n\nThe cells in epithelial layers can be jammed in a glass-like state\,
they can flock\, or they can show active turbulent-like motility with cha
otic flows and motile topological defects. Active turbulence characterises
active nematics\, and we have been trying to understand why cells that ar
e\, on average\, isotropic can show nematic properties. Moreover\, it is s
urprising that single cells are contractile\, whereas the direction of mot
ion of topological defects in many confluent cell layers suggests that the
layers are behaving as an extensile material.\n\nSpeaker:\n* Professor Ju
lia Yeomans (University of Oxford)
LOCATION:Zoom - see email invite.
URL:https://www.ph.ed.ac.uk/events/2021/81794-are-confluent-cell-layers-ex
tensile-or-contractile
END:VEVENT
BEGIN:VEVENT
CLASS:PUBLIC
UID:EVENT-81800@www.ph.ed.ac.uk
DTSTAMP:20220520T182951
CREATED:20210914T094439
LAST-MODIFIED:20211013T160003
STATUS:CONFIRMED
DTSTART;TZID=Europe/London:20211012T150000
DTEND;TZID=Europe/London:20211012T160000
SUMMARY:The thermodynamic uncertainty relation
DESCRIPTION: The thermodynamic uncertainty relation discovered in 2015 is
arguably one of the most promising insights arising from stochastic therm
odynamics. It relates the mean and fluctuations of any current to the over
all entropy production in a non-equilibrium steady state. It provides a lo
wer bound on the inevitable cost of temporal precision of processes\, lead
ing\, e.g. to the minimal cost for measuring time in a finite temperature
environment. As a tool for thermodynamic inference\, it gives a model-free
universal upper bound on the efficiency of molecular motors in terms of e
xperimentally accessible observables. Recent generalizations are applicabl
e to periodically and time-dependently driven systems.\n\nSpeaker:\n* Prof
essor Udo Seifert (II. Institut fuer Theoretische Physik\, Universitaet St
uttgart)
LOCATION:Zoom - see email invite.
URL:https://www.ph.ed.ac.uk/events/2021/81800-the-thermodynamic-uncertaint
y-relation
END:VEVENT
BEGIN:VEVENT
CLASS:PUBLIC
UID:EVENT-81817@www.ph.ed.ac.uk
DTSTAMP:20220520T182951
CREATED:20210916T114443
LAST-MODIFIED:20211020T182322
STATUS:CONFIRMED
DTSTART;TZID=Europe/London:20211019T150000
DTEND;TZID=Europe/London:20211019T160000
SUMMARY:Competitive growth on a rugged front
DESCRIPTION:When competing species expand into new territory\, the populat
ion is dominated by descendants of a few successful ancestors at the expan
sion front. Successful ancestry is stochastic\, but biased by fitness of t
he individual\, as well as favorable geographic location. I will describe
a simple model of range expansion of competing bacteria\, in which reprodu
ction and competition only take place at the growing front. Based on symme
try considerations a pair of nonlinear stochastic partial differential equ
ations are constructed that describe the coevolution of the profile of the
growing surface and the composition of the bacterial species on the front
. Macroscopic manifestations (phenomenology) of these equations on growth
morphologies (patterns) and genealogical tracks of range expansion will be
presented.\n\nSpeaker:\n* Professor Mehran Kardar (Massachusetts Institut
e of Technology)
LOCATION:Zoom - see email invite.
URL:https://www.ph.ed.ac.uk/events/2021/81817-competitive-growth-on-a-rugg
ed-front
END:VEVENT
BEGIN:VEVENT
CLASS:PUBLIC
UID:EVENT-81804@www.ph.ed.ac.uk
DTSTAMP:20220520T182951
CREATED:20210914T185227
LAST-MODIFIED:20211028T160442
STATUS:CONFIRMED
DTSTART;TZID=Europe/London:20211026T150000
DTEND;TZID=Europe/London:20211026T160000
SUMMARY:Dynamics of Topological Defects in Active Nematics
DESCRIPTION:Topological defects - singular tears of the order parameter fi
eld that cannot be removed by smooth deformations - are often formed in qu
enches from the disordered state or when order is frustrated by curvature\
, external fields or boundary conditions. In equilibrium two-dimensional s
ystems\, such as thin films of superfluids\, crystals\, liquid crystals an
d magnets\, order-disorder transitions are controlled by defect unbinding
described via the Berezinskii-Kosterlitz-Thouless mapping of the statisti
cal physics of defects onto a Coulomb gas. In active liquid crystals\, top
ological defects become motile particles and proliferate spontaneously in
the state of self-sustained turbulent-like motion ubiquitously observed in
these systems.\n\nIn this talk I will outline a framework for formulating
the statistical physics of defects in active nematics as quasiparticles a
nd show that by viewing the active nematic as a collection of swarming and
interacting active defects\, the onset of active turbulence can be descri
bed as an activity-driven defect unbinding transition. A hydrodynamic theo
ry of the gas of unbound defects additonally captures states of hierarchic
ally organized active matter and the role of activity gradients for confin
ing defects and harnessing active flows.\n\nSpeaker:\n* Professor Cristina
Marchetti (UC Santa Barbara)
LOCATION:Zoom - see email invite.
URL:https://www.ph.ed.ac.uk/events/2021/81804-dynamics-of-topological-defe
cts-in-active-nematics
END:VEVENT
BEGIN:VEVENT
CLASS:PUBLIC
UID:EVENT-81836@www.ph.ed.ac.uk
DTSTAMP:20220520T182951
CREATED:20210923T143654
LAST-MODIFIED:20211104T104215
STATUS:CONFIRMED
DTSTART;TZID=Europe/London:20211102T150000
DTEND;TZID=Europe/London:20211102T160000
SUMMARY:Stochastic dynamics of single molecules across phase boundaries
DESCRIPTION:We discuss the stochastic trajectories of single molecules in
a phase-separated liquid\, when a dense and a dilute phase coexist. Starti
ng from a continuum theory of macroscopic phase separation we derive a sto
chastic Langevin equation for molecular trajectories that takes into accou
nt thermal fluctuations. We find that molecular trajectories can be descri
bed as diffusion with drift in an effective potential\, which has a steep
gradient at phase boundaries. We discuss how the physics of phase coexiste
nce affects the statistics of molecular trajectories and in particular the
statistics of displacements of molecules crossing a phase boundary. We al
so investigate the consequences of thermodynamic equilibrium on the statis
tics of single molecule trajectories and the changes brought about by non-
equilibrium conditions. Bridging between single-molecule dynamics and coll
ective dynamics at macroscopic scales we provide a framework to study sing
le-molecule dynamics in phase-separating systems\, which can be used to in
fer key phase separation parameters from the statistics of single-molecule
trajectories.\n\nSpeaker:\n* Stefano Bo (Max Planck Institute for the Phy
sics of Complex Systems)
URL:https://www.ph.ed.ac.uk/events/2021/81836-stochastic-dynamics-of-singl
e-molecules-across-phase-boundaries
END:VEVENT
BEGIN:VEVENT
CLASS:PUBLIC
UID:EVENT-81801@www.ph.ed.ac.uk
DTSTAMP:20220520T182951
CREATED:20210914T161859
LAST-MODIFIED:20211111T160432
STATUS:CONFIRMED
DTSTART;TZID=Europe/London:20211109T150000
DTEND;TZID=Europe/London:20211109T160000
SUMMARY:Statistical physics of learning in neural networks: the importance
of data structure
DESCRIPTION:The highly structured character of data used in training deep
networks is a crucial ingredient of their performance. Yet theoretical wor
k has largely overlooked this structure. Modelling structured data\, analy
zing the learning and the generalization of deep networks trained on this
data\, are major challenges. This talk will describe several recent develo
pments in this direction.\n\nWe shall introduce a generative model for str
uctured datasets\, the hidden manifold model\, in which high-dimensional i
nputs lie on a lower-dimensional folded manifold\, as in real datasets. Th
e analytic study of learning with such data ensembles is possible due to a
Gaussian equivalence stating that the key metrics of interest\, such as t
he training and test errors\, can be fully captured by an appropriately ch
osen Gaussian model. This can also be extended to data drawn from pre-trai
ned generative models. The Gaussian equivalence\, which can be proven in s
ome cases\, allows to apply statistical physics methods that accurately de
scribe the learning dynamics and the phase diagram.\n\nSpeaker:\n* Profess
or Marc Mézard (École normale supérieure)
LOCATION:Zoom - see email invite.
URL:https://www.ph.ed.ac.uk/events/2021/81801-statistical-physics-of-learn
ing-in-neural-networks-the-importance-of-data-structure
END:VEVENT
BEGIN:VEVENT
CLASS:PUBLIC
UID:EVENT-81808@www.ph.ed.ac.uk
DTSTAMP:20220520T182951
CREATED:20210915T082327
LAST-MODIFIED:20211116T170827
STATUS:CONFIRMED
DTSTART;TZID=Europe/London:20211116T150000
DTEND;TZID=Europe/London:20211116T160000
SUMMARY:First-Passage Resetting and its Application to Optimization and to
Wealth Sharing
DESCRIPTION:When does a diffusing particle first reach a specified locatio
n? This question is answered by the first-passage probability. First-passa
ge ideas underlie diverse phenomena\, such as the triggering of integrate-
and-fire neurons in the brain to the execution of stock options. In this t
alk\, I'll first present basic facts about first-passage processes. Then
I'll discuss the notion of first-passage resetting\, in which a diffusing
particle is reset to its starting point whenever a given threshold is fir
st reached. Finally\, I'll present applications of these ideas to optimi
zation in a toy mechanical system and to a simple model of wealth sharing.
\n\nSpeaker:\n* Professor Sidney Redner (Santa Fe Institute)
LOCATION:Zoom - see email invite.
URL:https://www.ph.ed.ac.uk/events/2021/81808-first-passage-resetting-and-
its-application-to-optimization-and-to-wealth-sharing
END:VEVENT
BEGIN:VEVENT
CLASS:PUBLIC
UID:EVENT-81924@www.ph.ed.ac.uk
DTSTAMP:20220520T182951
CREATED:20211016T145408
LAST-MODIFIED:20211126T161950
STATUS:CONFIRMED
DTSTART;TZID=Europe/London:20211123T150000
DTEND;TZID=Europe/London:20211123T160000
SUMMARY:An unexpected bridge between Black Hole sand Glasses
DESCRIPTION:The SYK model and the important role of reparametrization inva
riance there\n Brief recap of classical glass phenomenology and mean-field
glass theory (Parisi and dynamics)\n Reparametrization invariance in glass
y dynamics. Why it is essential for the consistency of the construction -
also: softness is physically relevant and measurable\n For every glass the
re is a strange liquid (or metal)\n(Jorge originally intended to present o
n the topic "Quantum fluctuation dissipation"\, but felt that would overla
p with Laura Foini's talk in February next year.)\n\nSpeaker:\n* Jorge Kur
chan (École Normale Supérieure\, Paris)
LOCATION:Online - see email.
URL:https://www.ph.ed.ac.uk/events/2021/81924-an-unexpected-bridge-between
-black-hole-sand-glasses
END:VEVENT
BEGIN:VEVENT
CLASS:PUBLIC
UID:EVENT-82031@www.ph.ed.ac.uk
DTSTAMP:20220520T182951
CREATED:20211115T190856
LAST-MODIFIED:20211201T093246
STATUS:CONFIRMED
DTSTART;TZID=Europe/London:20211130T150000
DTEND;TZID=Europe/London:20211130T160000
SUMMARY:Hydrodynamic interactions induce microphase separation in active s
ystems
DESCRIPTION:Free of the constraints of equilibrium statistical physics\, a
ctive matter systems exhibit a variety of unexpected phenomena. Their ori
gin lies in detailed balance being broken by the self-propulsion and inter
actions between active particles at the microscopic level. Such systems c
an often be classified as either 'dry' or 'wet' active matter when dominat
ed by friction with their surroundings and long-ranged hydrodynamic inter
actions\, respectively. Manifestations of broken detailed balance in ac
tive matter often comprise novel phases that are absent in equilibrium. In
dry active matter\, an archetypal example is given by the motility-induce
d phase separation\, while in wet active matter\, the same role is played
by 'bacterial turbulence' - large-scale collective motion of a dilute susp
ension of motile organisms. \n\n\n In this talk we introduce a model that
simultaneously includes long-range hydrodynamic interactions between micr
oswimmers and microscopic ingredients necessary for the formation of moti
lity-induced clusters. We demonstrate that the model yields a variety of
new phases. Most importantly\, we find that the growth of motility-induced
clusters is arrested by hydrodynamic interactions leading to microphase
separation. We discuss its mechanism and propose a phase diagram for such
systems. \n\nSpeaker:\n* Professor Alexander Morozov (School of Physics &
Astronomy\, University of Edinburgh)
LOCATION:Online - see email.
URL:https://www.ph.ed.ac.uk/events/2021/82031-hydrodynamic-interactions-in
duce-microphase-separation-in-active-systems
END:VEVENT
BEGIN:VEVENT
CLASS:PUBLIC
UID:EVENT-81951@www.ph.ed.ac.uk
DTSTAMP:20220520T182951
CREATED:20211026T141217
LAST-MODIFIED:20211207T184130
STATUS:CONFIRMED
DTSTART;TZID=Europe/London:20211207T150000
DTEND;TZID=Europe/London:20211207T160000
SUMMARY:Disordered collective motion in dense assemblies of persistent par
ticles
DESCRIPTION:I will discuss how the nonequilibrium driving forces introduce
d by biological activity or by physical self-propulsion mechanisms generic
ally affect the structure\, dynamics and phase behavior of dense active me
dia. I will use theory and computer simulations to analyse simple models o
f such active materials\, in particular dense systems of self-propelled pa
rticles. I will borrow concepts from the equilibrium physics of amorphous
and crystalline materials to provide a physical understanding of experimen
tal observations performed with more complex systems such as self-propelle
d colloidal and granular systems\, biological tissues\, and bacterial colo
nies with a particular emphasis on the emergence of collective particle mo
tion triggered by self-propulsion.\n\nSpeaker:\n* Dr Ludovic Berthier (Uni
versite de Montpellier)
LOCATION:Online - see email.
URL:https://www.ph.ed.ac.uk/events/2021/81951-disordered-collective-motion
-in-dense-assemblies-of-persistent-particles
END:VEVENT
BEGIN:VEVENT
CLASS:PUBLIC
UID:EVENT-81953@www.ph.ed.ac.uk
DTSTAMP:20220520T182951
CREATED:20211026T143817
LAST-MODIFIED:20211215T144254
STATUS:CONFIRMED
DTSTART;TZID=Europe/London:20211214T150000
DTEND;TZID=Europe/London:20211214T160000
SUMMARY:To reset or not to reset\, that is the question!
DESCRIPTION:Stochastic resetting [1]\, i.e\, stopping an ongoing dynamical
process to start over\, can either accelerate or hinder a first-passage p
rocess. Tuning system parameters can invert the effect of resetting on the
mean completion time of the process\, leading to a resetting transition.
In this talk\, I shall first explore the exact conditions where stochastic
resetting accelerates diffusive transport for a couple of analytically tr
actable systems\, viz.\,\n\n(i) diffusion in a linear potential\, where th
e resetting transition is found to be governed by the Péclet number [2]\,
\n\n(ii) diffusion in a logarithmic potential\, that exhibits a series of
dynamical transitions when the constant strength of the potential in the u
nits of thermal energy\, is tuned [3].\n\nBased on the common trends that
these model systems show\, a general framework can be proposed that reveal
s that the resetting transition is governed by an interplay between therma
l and potential energy\; when thermal energy dominates the dynamics\, rese
tting can expedite the process [4]. Finally\, considering a toy model for
space-dependent diffusion \,I shall show that whenever a dynamical process
is diffusion-controlled\, resetting can\, in principle\, accelerate it [5
]. We believe that our analysis will be useful in a variety of natural as
well as man-made systems where resetting plays a crucial role in diffusive
transport.\n\nReferences:\n\n[1] M. R. Evans\, S. N. Majumdar\, and G. Sc
hehr\, J. Phys. A: Math. Theor. 53\, 193001(2020).\n\n[2] S. Ray\, D. Mond
al and S. Reuveni\, J. Phys. A: Math. Theor. 52\, 255002 (2019).\n\n[3] S.
Rayand S. Reuveni\, J. Chem. Phys. 152\, 234110\, (2020).\n\n[4] S. Rayan
d S. Reuveni\, J. Chem. Phys. (Comm.) 154\, 171103\, (2021).\n\n[5] S. Ray
\, J. Chem. Phys. 153\, 234904\, (2020).\n\nSpeaker:\n* Dr Somrita Ray (In
dian Institute of Technology Tirupati)
LOCATION:Online - see email.
URL:https://www.ph.ed.ac.uk/events/2021/81953-to-reset-or-not-to-reset-tha
t-is-the-question
END:VEVENT
BEGIN:VEVENT
CLASS:PUBLIC
UID:EVENT-81959@www.ph.ed.ac.uk
DTSTAMP:20220520T182951
CREATED:20211027T160726
LAST-MODIFIED:20220112T143909
STATUS:CONFIRMED
DTSTART;TZID=Europe/London:20220111T150000
DTEND;TZID=Europe/London:20220111T160000
SUMMARY:Statistical Physics Analysis of Ecosystems
DESCRIPTION:I will first start with a general introduction on theoretical
ecology\, stressing the reasons that make connections with statistical phy
sics interesting and timely. I will then focus on Lotka-Volterra equations
\, which provide a general model to study large assemblies of strongly int
eracting degrees of freedom in many different fields: biology\, economy an
d in particular ecology. I will present our ongoing works on Lotka-Volterr
a equations for ecosystems formed by many species. I will show that such s
ystems display different “phases” and collective behaviors\, from simp
le regimes with a single equilibrium to complex ones characterized by eith
er an exponential number of multiple equilibria\, all poised at the edge o
f stability\, or chaotic dynamics. Finally\, I will present a study of t
he interplay between artificial selection at the community level and ecolo
gical dynamics. The aim of this talk is to show that methods rooted in
statistical physics of disordered systems allow to shed new light on open
and debated questions in ecology\, and to present a class of models displa
ying very interesting non-equilibrium dynamics. \n\nSpeaker:\n* Professo
r Giulio Biroli (Ecole Normale Supérieure\, Paris\, France )
LOCATION:Online - see email.
URL:https://www.ph.ed.ac.uk/events/2022/81959-statistical-physics-analysis
-of-ecosystems
END:VEVENT
BEGIN:VEVENT
CLASS:PUBLIC
UID:EVENT-81950@www.ph.ed.ac.uk
DTSTAMP:20220520T182951
CREATED:20211026T102359
LAST-MODIFIED:20220119T101822
STATUS:CONFIRMED
DTSTART;TZID=Europe/London:20220118T150000
DTEND;TZID=Europe/London:20220118T160000
SUMMARY:Mechanics and geometry of growing tissues
DESCRIPTION:The mechanical properties of biological tissues are generall
y studied either at a macroscopic level by considering the tissue as a liq
uid (with a non-conserved number of cells) or at a microscopic cellular le
vel by a vertex model that considers the tissue as an evolving graph. \n
We derive a covariant coarse-grained continuum model of a generalized 2 di
mensional vertex model of epithelial tissues. The formulation describes ti
ssues with different underlying geometries\, and allows for analytical des
cription of the macroscopic behavior starting from the microscopic discret
e vertex model. Using a geometrical approach and out-of-equilibrium stat
istical mechanics\, we calculate various mechanical properties of a tissue
\, and their dependence on different variables\, including activity\, and
disorder. Both plastic cellular rearrangements and the elastic response\
, depend on the existence of mechanical residual stresses at a cellular
level. Our main result is an explicit calculation of the cell pressure in
a homeosatic state. Additionally\, we show that the homeostatic pressure
can be negative and due to the existence of mechanical residual stresses.
Using this geometric model we can readily distinct between elasticity and
plasticity in a growing\, flowing\, tissue.\n\nDoron Grossman and Jean-Fr
ançois Joanny\n\nSpeaker:\n* Professor Jean-Francois Joanny (Collège de
France\, Paris\, France.)
LOCATION:Online - see email.
URL:https://www.ph.ed.ac.uk/events/2022/81950-mechanics-and-geometry-of-gr
owing-tissues
END:VEVENT
BEGIN:VEVENT
CLASS:PUBLIC
UID:EVENT-82063@www.ph.ed.ac.uk
DTSTAMP:20220520T182951
CREATED:20211201T100807
LAST-MODIFIED:20220203T084539
STATUS:CONFIRMED
DTSTART;TZID=Europe/London:20220125T150000
DTEND;TZID=Europe/London:20220125T160000
SUMMARY:The mathematics of active matter
DESCRIPTION:A flock of birds\, a shoal of fish\, a swarm of robots\, a
colony of swimming bacteria\; these are examples of systems composed of i
nteracting units that consume energy and collectively generate motion and
mechanical forces on their environment. They show a rich variety of collec
tive behaviour\, much of which remains mysterious. In recent years we have
come to call such systems active matter. Clearly\, biology (living system
s) provides numerous examples of these active matter systems. \n\nI wil
l explain why we call them active matter. Essentially\, this is because th
ey share some of the properties of the constituents of what we call matter
\, i.e. solids\, liquids and gases in that they are made of many interac
ting components. However they have fundamental differences in that many co
nservation laws that govern the interactions of normal (passive) matter ar
e not obeyed by their active components.\n\n(Equilibrium) statistical mech
anics has formed the framework for how we understand the properties of mat
ter. I will argue that ideas developed in statistical mechanics must be au
gmented by a number of new mathematical structures to describe these syste
ms. Then I will describe some recent theoretical work developing this fram
ework for characterising the behaviour of active matter systems. Finally I
will apply it to describe some recent experimental work studying coll
ections of electrically-driven colloidal rollers moving in two dimensions.
\n\nSpeaker:\n* Professor Tanniemola Liverpool (University of Bristol)
LOCATION:Online - see email.
URL:https://www.ph.ed.ac.uk/events/2022/82063-the-mathematics-of-active-ma
tter
END:VEVENT
BEGIN:VEVENT
CLASS:PUBLIC
UID:EVENT-81964@www.ph.ed.ac.uk
DTSTAMP:20220520T182951
CREATED:20211028T105954
LAST-MODIFIED:20220202T093015
STATUS:CONFIRMED
DTSTART;TZID=Europe/London:20220201T150000
DTEND;TZID=Europe/London:20220201T160000
SUMMARY:From gambling to growing in uncertain environments
DESCRIPTION:In unpredictably varying environments\, it is advantageous for
individuals in a population to accept a reduction of their short-term rep
roductive success in exchange for longer-term risk reduction. This phenome
non called bet-hedging\, protects the population from potential damages as
sociated with environmental variations. It is universally present in biolo
gy for instance in bacteria resistance to antibiotics\, in plants delaying
germination or in virus evolution.\n The idea of bet-hedging is perhaps b
est illustrated using Kelly's model\, originally introduced in the context
of gambling models such as horse races. The gambler strives to optimize h
is/her capital growth by placing appropriate bets similarly to the biologi
cal population which invests in appropriate phenotypes to grow and survive
. Following this idea\, we first analyze the trade-off between the average
growth rate of the capital of the gambler and the risk the gambler takes
in Kelly's model [1]. Secondly\, we discuss how to extend that model to de
scribe adaptive strategies of gambling [2]. \n Then\, we turn to the mod
eling of a biological population embedded in fluctuating environments. Ass
uming no sensing mechanism\, we focus on the simplest non-trivial case\, i
.e. two randomly switching phenotypes subjected to two stochastically swit
ching environments. Since the optimal asymptotic (long term) growth rate w
as studied elsewhere\; we focus on finite time growth rate fluctuations.
An exact asymptotic expression for the variance\, alongside with approxima
tions valid in different regimes\, are tested numerically. Our simulations
of the dynamics suggest a close connection between this variance and the
extinction probability\, understood as risk for the population. Motivated
by our previous analysis of Kelly's gambling model\, we study the trade-of
f between the average growth rate and the variance of the biological popul
ation [3]. Despite considerable differences between the two models\, we fi
nd similar optimal trade-off curves (Pareto fronts)\, suggesting that our
conclusions are robust\, and broadly applicable in various fields ranging
from biology/ecology to economics.\n References:\n [1] L. Dinis et
al.\, Phase transitions in optimal betting strategies\, EPL 131\, 60005 (
2020).\n [2] A. Despons et al.\, Adaptive strategy in Kelly's hors
e race model\, arXiv:2201.03387 (2022)\n [3] L. Dinis et al.\, Par
eto-optimal trade-off for phenotypic switching in a stochastic environment
\, https://www.biorxiv.org/content/10.1101/2022.01.18.476793v1\, (2022)\n
\nSpeaker:\n* Dr David Lacoste (ESPCI\, Paris)
LOCATION:Online - see email.
URL:https://www.ph.ed.ac.uk/events/2022/81964-from-gambling-to-growing-in-
uncertain-environments
END:VEVENT
BEGIN:VEVENT
CLASS:PUBLIC
UID:EVENT-82021@www.ph.ed.ac.uk
DTSTAMP:20220520T182951
CREATED:20211112T091258
LAST-MODIFIED:20220209T104826
STATUS:CONFIRMED
DTSTART;TZID=Europe/London:20220208T150000
DTEND;TZID=Europe/London:20220208T160000
SUMMARY:Multibody effects in active particle systems\, and what working in
large space dimension teaches us
DESCRIPTION:Systems made of a large number of self-propelled particles liv
e very far from equilibrium\, which opens the door to unexpected collectiv
e behaviors\, such as the motility-induced phase separation (MIPS). While
a phenomenological understanding of such phenomena was almost immediatel
y available\, microscopics-based approaches are usually difficult to condu
ct. By embedding these many-body systems in a large-dimensional space\, so
me simplifications occur\, and these allow us to pinpoint fundamental phys
ical differences between a conventional equilibrium phase separation drive
n by pairwise forces\, and MIPS\, which had eluded phenomenological\, coar
se-grained\, descriptions. These lie in the intrinsically many-body natu
re of interactions in systems of active particles. \n\nWork done in colla
boration with Thibaut Arnoulx de Pirey\n\nSpeaker:\n* Professor Frédéric
van Wijland (Laboratoire Matière et Systèmes Complexes\, Université de
Paris.)
URL:https://www.ph.ed.ac.uk/events/2022/82021-multibody-effects-in-active-
particle-systems-and-what-working-in-large-space-dimension-teaches-us
END:VEVENT
BEGIN:VEVENT
CLASS:PUBLIC
UID:EVENT-81966@www.ph.ed.ac.uk
DTSTAMP:20220520T182951
CREATED:20211028T154303
LAST-MODIFIED:20220216T082732
STATUS:CONFIRMED
DTSTART;TZID=Europe/London:20220215T150000
DTEND;TZID=Europe/London:20220215T160000
SUMMARY:Quantum bounds and fluctuation-dissipation relations
DESCRIPTION:In recent years\, there has been intense attention on the cons
traints imposed by quantum mechanics on the dynamics of many-body systems
at low temperatures\, triggered by the postulation and derivation of quant
um bounds on transport coefficients or on the chaos rate. In this talk I w
ill discuss the quantum fluctuation-dissipation theorem (the KMS condition
s) as the principle underlying bounds on correlation time scales. By resta
ting the problem in a replicated space\, we show that the quantum bound to
chaos is in fact a direct consequence of the KMS condition\, as applied t
o a particular pair of two-time correlation and response functions. Encour
aged by this\, we describe how quantum fluctuation-dissipation relations a
ct in general as a blurring of the time-dependence of correlations\, which
can imply bounds on their decay rates. Thinking in terms of fluctuation-d
issipation opens a direct connection between bounds and other thermodynami
c properties.\n\nS. Pappalardi\, L. Foini\, J. Kurchan\, arXiv:2110.03497\
n\nSpeaker:\n* Dr Laura Foini (CNRS - Institut de Physique Théorique\, Un
iversité Paris-Saclay\, France)
LOCATION:Online - see email.
URL:https://www.ph.ed.ac.uk/events/2022/81966-quantum-bounds-and-fluctuati
on-dissipation-relations
END:VEVENT
BEGIN:VEVENT
CLASS:PUBLIC
UID:EVENT-81962@www.ph.ed.ac.uk
DTSTAMP:20220520T182951
CREATED:20211028T104407
LAST-MODIFIED:20220223T113211
STATUS:CONFIRMED
DTSTART;TZID=Europe/London:20220222T150000
DTEND;TZID=Europe/London:20220222T160000
SUMMARY:Many-Body Localization: integrability\, glassiness\, and fluctuati
on-driven transitions
DESCRIPTION:Many-Body Localization (MBL) is a peculiar form of ergodicity
breaking and out-of-equilibrium dynamics which occurs in certain interacti
ng quantum systems subject to quenched disorder. In the first part of this
talk\, I will briefly discuss the connection between localization\, integ
rability and glassiness\, in order to motivate the claim that Many-Body L
ocalized systems are both integrable and glassy\, albeit in their own spec
ial way. In the second part of the talk\, I will discuss a toy model to ca
pture the interplay between quenched disorder leading to localisation and
slow\, thermally induced fluctuations affecting the effective local disord
er of the system. I will summarise the rich phenomenology brought about by
these additional fluctuations\, stressing in particular the connections t
o the unfreezing transition and configurational chaos in the simplest mode
ls of glassy systems. This part is based on joint work with Markus Mueller
.\n\nSpeaker:\n* Valentina Ros Dr (CNRS - Université Paris Saclay\, Orsay
)
LOCATION:Online - see email.
URL:https://www.ph.ed.ac.uk/events/2022/81962-many-body-localization-integ
rability-glassiness-and-fluctuation-driven-transitions
END:VEVENT
BEGIN:VEVENT
CLASS:PUBLIC
UID:EVENT-82048@www.ph.ed.ac.uk
DTSTAMP:20220520T182951
CREATED:20211124T184048
LAST-MODIFIED:20220304T115015
STATUS:CONFIRMED
DTSTART;TZID=Europe/London:20220301T150000
DTEND;TZID=Europe/London:20220301T160000
SUMMARY:Self-Organization of Lifelike Behaviors
DESCRIPTION:Life is a multifarious bundle of distinct physical phenomena t
hat are distinctive\, but not unique to\, living things. Self-replication\
, energy harvesting\, and predictive sensing are three such phenomena\, an
d each can be given a clear physical definition. In this talk\, we will re
port recent progress in understanding what physical conditions are require
d for the spontaneous emergence of these various lifelike behaviors from a
ssemblages of simple\, interacting components.\n\nSpeaker:\n* Jeremy Engla
nd (Georgia Tech)
LOCATION:Online - see email.
URL:https://www.ph.ed.ac.uk/events/2022/82048-self-organization-of-lifelik
e-behaviors
END:VEVENT
BEGIN:VEVENT
CLASS:PUBLIC
UID:EVENT-82141@www.ph.ed.ac.uk
DTSTAMP:20220520T182951
CREATED:20220128T090340
LAST-MODIFIED:20220311T092957
STATUS:CONFIRMED
DTSTART;TZID=Europe/London:20220308T150000
DTEND;TZID=Europe/London:20220308T160000
SUMMARY:Structured population modeling in demography\, cell biology\, and
immunology
DESCRIPTION:I will highlight the development of mathematical models for st
ructured populations in a number of biological settings. Starting from th
e canonical age-structured McKendrick model\, I will present a model of th
e one-child policy (which itself was implemented as a result of modeling)
and then present a stochastic generalization of it. Structured population
s also naturally arise in cell proliferation models. We adapt them to adde
r-sizer-timer type models and also present stochastic versions. Finally
\, I will outline a new application to T cells with different HIV integra
tion sites\, and analyze this model in the context of ranked clone abundan
ces.\n\nSpeaker:\n* Professor Tom Chou (UCLA)
LOCATION:Online - see email
URL:https://www.ph.ed.ac.uk/events/2022/82141-structured-population-modeli
ng-in-demography-cell-biology-and-immunology
END:VEVENT
BEGIN:VEVENT
CLASS:PUBLIC
UID:EVENT-82123@www.ph.ed.ac.uk
DTSTAMP:20220520T182951
CREATED:20220124T094458
LAST-MODIFIED:20220314T153119
STATUS:CANCELLED
DTSTART;TZID=Europe/London:20220315T150000
DTEND;TZID=Europe/London:20220315T160000
SUMMARY:[CANCELLED] Protein structure and dynamics from a statistical pers
pective
DESCRIPTION:Proteins regulate and manage all processes that make up life a
s we know it. Understanding their structure and how their dynamics relates
to their function allows us to unravel intricate and complex biological p
rocess. A better understanding of these processes can then be used to regu
late them\, and fight e.g. disease. Molecular simulations can shed light i
nto how proteins work\, but rigorous statistical methods are needed to ext
ract meaningful information from these simulations. To obtain quantitative
data that can be compared to experimental data we need a rigorous mathema
tical framework. Using Markov state models are a way of analysing simulati
on trajectory data and in combination with Bayesian inference methods we
can build optimal models from our simulations that are both predictive\,
but also give atomistic details otherwise obscured in experiments. In this
talk I will discuss the mathematical background of Markov state models an
d how to make optimal choices when constructing them from simulation data.
I will also highlight how the results of these models can be used to shed
light on experimental results of clinically relevant proteins such as Cyc
lophilin A. \n\nSpeaker:\n* Dr Antonia Mey (School of Chemistry\, Univers
ity of Edinburgh)
LOCATION:Online - see email.
URL:https://www.ph.ed.ac.uk/events/2022/82123-protein-structure-and-dynami
cs-from-a-statistical-perspective
END:VEVENT
BEGIN:VEVENT
CLASS:PUBLIC
UID:EVENT-82160@www.ph.ed.ac.uk
DTSTAMP:20220520T182951
CREATED:20220203T083323
LAST-MODIFIED:20220323T144217
STATUS:CONFIRMED
DTSTART;TZID=Europe/London:20220322T150000
DTEND;TZID=Europe/London:20220322T160000
SUMMARY:Fluctuations of a swarm of Brownian bees
DESCRIPTION:The “Brownian bees” model is a new member of a family of B
runet-Derrida particle systems which mimic different aspects of biological
selection. The model describes an ensemble of $N$ independent branching
Brownian particles. When a particle branches into two particles\, the part
icle farthest from the origin is eliminated so as to keep the number of pa
rticles constant. In the limit of $N \\to \\infty$\, the coarse-grained pa
rticle density is governed by the solution of a free boundary problem for
a simple reaction-diffusion equation. At long times the particle density a
pproaches a spherically symmetric steady-state solution with a compact sup
port. We studied fluctuations of the “swarm of bees” due to the random
character of the branching Brownian motion in the limit of large but fini
te $N$. We considered a one-dimensional setting and focused on two fluctua
ting quantities: the swarm center of mass $X(t)$ and the swarm radius $l(t
)$. Unsurprisingly\, the variance of $X (t)$ scales as $\\frac{1}{N}$. The
variance of $l(t)$\, however\, exhibits an anomalous scaling $\\frac{\\ln
N}{N}$. This anomaly appears because all spatial scales\, including a nar
row region near the edges of the swarm (where only a few particles are pre
sent)\, contribute to the variance. I will also briefly discuss some large
-deviation properties of the model.\n\nWork done in collaboration with Mao
r Siboni and Pavel Sasorov\n\nSpeaker:\n* Professor Baruch Meerson (Racah
Institute of Physics\, Hebrew University of Jerusalem )
LOCATION:Online - see email.
URL:https://www.ph.ed.ac.uk/events/2022/82160-fluctuations-of-a-swarm-of-b
rownian-bees
END:VEVENT
BEGIN:VEVENT
CLASS:PUBLIC
UID:EVENT-82161@www.ph.ed.ac.uk
DTSTAMP:20220520T182951
CREATED:20220203T164622
LAST-MODIFIED:20220402T153515
STATUS:CONFIRMED
DTSTART;TZID=Europe/London:20220329T150000
DTEND;TZID=Europe/London:20220329T160000
SUMMARY:Non-Gaussian random matrices predict the stability of feasible Lot
ka-Volterra communities
DESCRIPTION:Nearly 50 years ago Robert May sparked the “diversity-stabil
ity debate” in ecology. Assuming that the so-called community matrix has
random entries May claims that an increased number of species promotes in
stability. A decade-long debate has ensued\, including a number of recent
high-profile papers extending May’s work to matrices with more structur
e. Much of the work in this area relies on random matrix theory. I will ex
plain what tools from disordered systems can deliver for the dynamics of
random Lotka-Volterra models. In this context\, I will also discuss recent
work on the spectra of random matrices with generalised correlations\, an
d show how May’s approach can be justified retrospectively\, provided o
ne focuses on the right ensemble of matrices. This ensemble turns out to b
e non-Gaussian\, and I will demonstrate how tools from disordered systems
can be used to calculate their spectra. Universality does not apply in th
is context\, higher-order non Gaussian statistics need to be accounted for
to properly predict the leading eigenvalue of community matrices arising
from random Lotka-Volterra dynamics.\n\nSpeaker:\n* Professor Tobias Galla
(University of Manchester)
LOCATION:Online - see email.
URL:https://www.ph.ed.ac.uk/events/2022/82161-non-gaussian-random-matrices
-predict-the-stability-of-feasible-lotka-volterra-communities
END:VEVENT
BEGIN:VEVENT
CLASS:PUBLIC
UID:EVENT-82168@www.ph.ed.ac.uk
DTSTAMP:20220520T182951
CREATED:20220207T163358
LAST-MODIFIED:20220407T101323
STATUS:CONFIRMED
DTSTART;TZID=Europe/London:20220405T150000
DTEND;TZID=Europe/London:20220405T160000
SUMMARY:Entropy production of non-reciprocal interactions
DESCRIPTION:Non-reciprocal interactions are very common in natural systems
. They can be used to explain the emergence of certain patterns such as bi
rd flocking. Generally\, systems with non-reciprocal interactions are out
of equilibrium\, although they can obey detailed balance under certain con
ditions. In this talk\, I will present a particle model with non-reciproca
l pair interactions between two species of drift-diffusive particles\, say
dogs and sheep. Following a path integral approach\, I will discuss the s
tationary two-point correlation function and the entropy production. Even
in the absence of drift\, detailed balance is broken by non-reciprocity ex
cept for a particular choice of pair interactions.\n\nSpeaker:\n* Dr Rosal
ba Garcia Millan (DAMTP\, University of Cambridge)
LOCATION:Online - see email.
URL:https://www.ph.ed.ac.uk/events/2022/82168-entropy-production-of-non-re
ciprocal-interactions
END:VEVENT
BEGIN:VEVENT
CLASS:PUBLIC
UID:EVENT-82172@www.ph.ed.ac.uk
DTSTAMP:20220520T182951
CREATED:20220210T083540
LAST-MODIFIED:20220214T084656
STATUS:CONFIRMED
DTSTART;TZID=Europe/London:20220412T150000
DTEND;TZID=Europe/London:20220412T160000
SUMMARY:Stochastic Thermodynamics: cost of precise biochemical oscillation
s and active heat engines
DESCRIPTION:I will provide a brief introduction to stochastic thermodynami
cs\, a modern theoretical framework that generalizes thermodynamics to sm
all nonequilibrium systems. Two prominent relations in the field will be
discussed. The older fluctuation theorem and the more recent thermodynami
c uncertainty relation that we obtained in 2015. I will then talk about
two of our recent results. First\, for biochemical oscillations\, such as
circadian rhythms\, in stochastic systems\, we have conjectured the un
iversal minimal free energy cost of coherent oscillations. Second\, activ
e cyclic heat engines are heat engines with a working substance is in th
e presence of hidden dissipative degrees of freedom such as bacteria. In
this case\, the external bath is an active medium (or active matter). We
have derived a generic second law for active heat engines\, which has been
a challenge since active heat engines have been introduced in an experim
ent in 2016. \n\nSpeaker:\n* Dr Andre Cardoso Barato (University of Ho
uston)
LOCATION:Online - see email.
URL:https://www.ph.ed.ac.uk/events/2022/82172-stochastic-thermodynamics-co
st-of-precise-biochemical-oscillations-and-active-heat-engines
END:VEVENT
BEGIN:VEVENT
CLASS:PUBLIC
UID:EVENT-82229@www.ph.ed.ac.uk
DTSTAMP:20220520T182951
CREATED:20220320T110514
LAST-MODIFIED:20220420T092438
STATUS:CONFIRMED
DTSTART;TZID=Europe/London:20220419T150000
DTEND;TZID=Europe/London:20220419T160000
SUMMARY:Inspection Paradox Approach to Stochastic Resetting
DESCRIPTION:Passengers arriving at a bus stop at a random time may on aver
age wait longer than the mean time between bus arrivals—a counter-intuit
ive result\, since one expects to wait less when coming some time after th
e previous bus departed. In this talk\, I will review the origins of this
phenomenon\, a.k.a. the inspection paradox\, and use the lessons learned t
o explain why\, and under which conditions\, stochastic resetting expedite
s the completion of random processes: from diffusion\, via enzymatic react
ions\, and on to realistic versions of stochastic search and animal foragi
ng. To this end\, I will (re)derive a series of central results that appea
red in the literature using nothing but elementary mathematical tools—em
phasizing the strength of the approach and the deep probabilistic insight
it provides on stochastic resetting and how it works.\n\nReferences\n\n[1]
S. Reuveni\, M. Urbakh & J. Klafter\, PNAS 111 (12)\, 4391\, (2014).\n\n[
2] S. Reuveni\, Phys. Rev. Lett. 116\, 170601\, (2016).\n\n[3] A. Pal & S.
Reuveni\, Phys. Rev. Lett. 118\, 030603\, (2017).\n\n[4] T. Rotbart\, S.
Reuveni & M. Urbakh\, Nature Communications\, 9\, 779\, (2018).\n\n[5] A.
Pal\, I. Eliazar & S. Reuveni\, Phys. Rev. Lett. 122\, 020602\, (2019).\n\
n[6] S. Ray\, D. Mondal & S. Reuveni. J. Phys. A. 52\, 255002\, (2019).\n\
n[7] A. Pal\, Ł. Kuśmierz & S. Reuveni. Phys. Rev. Research 2 (4)\, 0431
74\, (2020).\n\n[8] A. Pal\, S. Kostinski & S. Reuveni. J. Phys. A: Math.
Theor. 55\, 021001\, (2022)\n\nSpeaker:\n* Dr Shlomi Reuveni (Tel Aviv Uni
versity)
LOCATION:Online - see email.
URL:https://www.ph.ed.ac.uk/events/2022/82229-inspection-paradox-approach-
to-stochastic-resetting
END:VEVENT
BEGIN:VEVENT
CLASS:PUBLIC
UID:EVENT-82232@www.ph.ed.ac.uk
DTSTAMP:20220520T182951
CREATED:20220321T095018
LAST-MODIFIED:20220427T093232
STATUS:CONFIRMED
DTSTART;TZID=Europe/London:20220426T150000
DTEND;TZID=Europe/London:20220426T160000
SUMMARY:Simplicity in high-dimensional dynamics of ecosystems
DESCRIPTION:Natural ecosystems exhibit astounding richness\, suggesting th
at we treat them as many-variable interacting systems. This raises two imp
ortant questions: What collective phenomena might be observed? And how do
such complex dynamical systems allow for many species to coexist? I’ll f
irst discuss dynamical phase-transitions in ecosystems\, and “thermodyna
mic” variables which determine their large-scale behaviour. Then\, I’l
l present a theory for how interactions between species organize to allow
many species to coexist. For both parts\, data from experiments confirm th
e theoretical predictions\, providing evidence for high-dimensionality in
those systems.\n\nSpeaker:\n* Professor Guy Bunin (Physics Department\, Te
chnion)
LOCATION:Online - see email.
URL:https://www.ph.ed.ac.uk/events/2022/82232-simplicity-in-high-dimension
al-dynamics-of-ecosystems
END:VEVENT
BEGIN:VEVENT
CLASS:PUBLIC
UID:EVENT-82227@www.ph.ed.ac.uk
DTSTAMP:20220520T182951
CREATED:20220320T095533
LAST-MODIFIED:20220504T144112
STATUS:CONFIRMED
DTSTART;TZID=Europe/London:20220503T150000
DTEND;TZID=Europe/London:20220503T160000
SUMMARY:Will large economies be stable?
DESCRIPTION:We study networks of firms in which inputs for production are
not easily substitutable\, as in several real-world supply chains. Buildin
g on Robert May's original argument for large ecosystems\, we argue that s
uch networks generically become dysfunctional when their size increases\,
when the heterogeneity between firms becomes too strong\, or when substitu
tability of their production inputs is reduced. At marginal stability and
for large heterogeneities\, we find that the distribution of firm sizes de
velops a power-law tail\, as observed empirically. Crises can be triggered
by small idiosyncratic shocks\, which lead to “avalanches” of default
s characterized by a power-law distribution of total output losses. This s
cenario would naturally explain the well-known “small shocks\, large bus
iness cycles” puzzle\, as anticipated long ago by Bak\, Chen\, Scheinkma
n\, and Woodford.\n\nSpeaker:\n* Professor Jean-Philippe Bouchaud (École
Normale Supérieure and Capital Fund Management)
LOCATION:Online - see email.
URL:https://www.ph.ed.ac.uk/events/2022/82227-will-large-economies-be-stab
le
END:VEVENT
BEGIN:VEVENT
CLASS:PUBLIC
UID:EVENT-82230@www.ph.ed.ac.uk
DTSTAMP:20220520T182951
CREATED:20220320T135442
LAST-MODIFIED:20220510T183436
STATUS:CONFIRMED
DTSTART;TZID=Europe/London:20220510T150000
DTEND;TZID=Europe/London:20220510T160000
SUMMARY:Protein structure and dynamics from a statistical perspective
DESCRIPTION:Proteins regulate and manage all processes that make up life a
s we know it. Understanding their structure and how their dynamics relates
to their function allows us to unravel intricate and complex biological p
rocess. A better understanding of these processes can then be used to regu
late them\, and fight e.g. disease. Molecular simulations can shed light i
nto how proteins work\, but rigorous statistical methods are needed to ext
ract meaningful information from these simulations. To obtain quantitative
data that can be compared to experimental data we need a rigorous mathema
tical framework. Using Markov state models are a way of analysing simulati
on trajectory data and in combination with Bayesian inference methods we
can build optimal models from our simulations that are both predictive\,
but also give atomistic details otherwise obscured in experiments. In this
talk I will discuss the mathematical background of Markov state models an
d how to make optimal choices when constructing them from simulation data.
I will also highlight how the results of these models can be used to shed
light on experimental results of clinically relevant proteins such as Cyc
lophilin A. \n\nSpeaker:\n* Dr Antonia Mey (School of Chemistry\, Univers
ity of Edinburgh)
LOCATION:Online - see email.
URL:https://www.ph.ed.ac.uk/events/2022/82230-protein-structure-and-dynami
cs-from-a-statistical-perspective
END:VEVENT
BEGIN:VEVENT
CLASS:PUBLIC
UID:EVENT-82207@www.ph.ed.ac.uk
DTSTAMP:20220520T182951
CREATED:20220307T091356
LAST-MODIFIED:20220518T124054
STATUS:CONFIRMED
DTSTART;TZID=Europe/London:20220517T150000
DTEND;TZID=Europe/London:20220517T160000
SUMMARY:Condensation transition in large deviations of the Ornstein-Uhlenb
eck process and of reset fractional Brownian motion
DESCRIPTION:I will present recent results for two problems related to stoc
hastic dynamics:\n\n(i) the full distribution of the time integral of the
nth moment of an Ornstein-Uhlenbeck process.\n\n(ii) the full distribution
of the mean position of a fractional Brownian motion with stochastic rese
tting to the origin.\n\nWe find that both in problem (i) for n>2\, and in
problem (ii)\, the long-time scaling form of the distribution obey large-d
eviation principles with anomalous exponents (i.e.\, the exponents are not
equal to 1).\n\nThe rate functions\, that we calculate exactly\, exhibit
first-order dynamical phase transitions which separate between a homogeneo
us phase that describes the Gaussian distribution of typical fluctuations\
, and a "condensed" phase that describes the tails of the distributions.\n
\nRemarkably\, the anomalous exponents and the rate functions are identica
l for the two problems\, up to scaling factors.\n\nThe talk is based on th
e two recent papers:\n\nN. R. Smith\, Phys. Rev. E 105\, 014120 (2022)\, a
nd\n\nN. R. Smith and S. N. Majumdar\, arXiv:2202.03546\n\nSpeaker:\n* Dr.
Naftali Smith (Ecole Normale Superieure and Ben-Gurion University of the
Negev)
LOCATION:Online - see email.
URL:https://www.ph.ed.ac.uk/events/2022/82207-condensation-transition-in-l
arge-deviations-of-the-ornstein-uhlenbeck-process-and-of-reset
END:VEVENT
BEGIN:VEVENT
CLASS:PUBLIC
UID:EVENT-82240@www.ph.ed.ac.uk
DTSTAMP:20220520T182951
CREATED:20220323T085137
LAST-MODIFIED:20220503T093914
STATUS:CONFIRMED
DTSTART;TZID=Europe/London:20220524T150000
DTEND;TZID=Europe/London:20220524T160000
SUMMARY:Field Theory of stochastic particle systems
DESCRIPTION:Field theory has been a major work-horse of statistical mechan
ics for a long time\, because it naturally accommodates many interacting
agents within the same framework and is easily extended to incorporate add
itional interactions and reactions. A particularly interesting applicatio
n is active matter\, where particles turn environmental energy\, i.e. che
mical fuel\, into mechanical energy\, for example self-propulsion. Doi-P
eliti field theories are designed to retain the particle nature of the c
onstituents of such stochastic particle systems. In the present talk\, I
will review how Doi-Peliti field theories can be built and used to chara
cterise active matter to reveal how it breaks time-reversal symmetry.\n\n
Speaker:\n* Dr Gunnar Pruessner (Imperial College\, London)
LOCATION:Online - see email.
URL:https://www.ph.ed.ac.uk/events/2022/82240-field-theory-of-stochastic-p
article-systems
END:VEVENT
BEGIN:VEVENT
CLASS:PUBLIC
UID:EVENT-82234@www.ph.ed.ac.uk
DTSTAMP:20220520T182951
CREATED:20220321T095439
LAST-MODIFIED:20220321T095531
STATUS:CONFIRMED
DTSTART;TZID=Europe/London:20220531T150000
DTEND;TZID=Europe/London:20220531T160000
SUMMARY:TBD
DESCRIPTION:TBD\n\nSpeaker:\n* Dr Anna Frishman (Physics Department\, Tech
nion)
LOCATION:Online - see email.
URL:https://www.ph.ed.ac.uk/events/2022/82234-tbd
END:VEVENT
BEGIN:VEVENT
CLASS:PUBLIC
UID:EVENT-82328@www.ph.ed.ac.uk
DTSTAMP:20220520T182951
CREATED:20220519T135420
LAST-MODIFIED:20220519T135420
STATUS:CONFIRMED
DTSTART;TZID=Europe/London:20220607T150000
DTEND;TZID=Europe/London:20220607T160000
SUMMARY:TBD
DESCRIPTION:TBD\n\nSpeaker:\n* Dr Chris Brackley (School of Physics & Astr
onomy\, University of Edinburgh)
LOCATION:Online - see email.
URL:https://www.ph.ed.ac.uk/events/2022/82328-tbd
END:VEVENT
BEGIN:VEVENT
CLASS:PUBLIC
UID:EVENT-82330@www.ph.ed.ac.uk
DTSTAMP:20220520T182951
CREATED:20220519T135754
LAST-MODIFIED:20220519T135833
STATUS:CONFIRMED
DTSTART;TZID=Europe/London:20220614T150000
DTEND;TZID=Europe/London:20220614T160000
SUMMARY:TBD
DESCRIPTION:TBD\n\nSpeaker:\n* Dr Katja Klobas (University of Oxford)
LOCATION:Online - see email.
URL:https://www.ph.ed.ac.uk/events/2022/82330-tbd
END:VEVENT
BEGIN:VEVENT
CLASS:PUBLIC
UID:EVENT-82333@www.ph.ed.ac.uk
DTSTAMP:20220520T182951
CREATED:20220519T140411
LAST-MODIFIED:20220520T164043
STATUS:CONFIRMED
DTSTART;TZID=Europe/London:20220621T150000
DTEND;TZID=Europe/London:20220621T160000
SUMMARY:Complex-tensor theory of simple smectics
DESCRIPTION:The same properties that make smectic phases so interesting co
ncomitantly contrive to make them challenging to model. They're interestin
g becacuse they are excellent systems for exploring self-assembly and topo
logy since they accommodate both dislocation- and disclination-type defect
s. However\, these cause the traditional complex scalar order parameter pr
oposed by de Gennes to be multi-valued\, creating ambiguity. While this is
not a fatal issue for theoreticians treating isolated defects\, it causes
crippling issues for numerical approaches that seek to model situations i
nvolving many defects. One option is to employ microscopic models that exp
licitly simulate each microscopic layer but this is computationally costly
and developing a macroscopic order parameter that can be used to simulate
many defects on a global coordinate system is required.\n\nWe present a c
omplex tensor order parameter to describe the local degree of lamellar ord
ering\, layer displacement and orientation and a phenomenological Landau t
heory that accounts for bulk\, compression and curvature free energies. Th
is proposed field theory is analogous to the Landau-de Gennes theory for n
ematics. This theory has the capacity to model both parallel and perpendic
ular contributions\, but can also reduce to previous employed models of si
mple smectics. Homeotropic and planar anchoring are included through equiv
alents to the nematic Rapini-Papoular and Fournier conditions\, respective
ly. We implement an overdamped a time-dependent Ginzburg–Landau model t
o solve for the relaxation dynamics of simple smectic systems. \n\nWe d
emonstrate the theory’s capability in describing both dislocations and d
isclinations\, as well as arrested configurations and colloid-induced loca
l ordering. Though versatile\, this theory considerably simplifies numeric
s\, facilitating future studies of smectic phases and their topological de
fects under large deformations in non-trivial geometries\n\nSpeaker:\n* Dr
. Tyler Shendruk (School of Physics & Astronomy\, University of Edinburgh)
LOCATION:Online - see email.
URL:https://www.ph.ed.ac.uk/events/2022/82333-complex-tensor-theory-of-sim
ple-smectics
END:VEVENT
BEGIN:VEVENT
CLASS:PUBLIC
UID:EVENT-82332@www.ph.ed.ac.uk
DTSTAMP:20220520T182951
CREATED:20220519T140224
LAST-MODIFIED:20220519T141811
STATUS:CONFIRMED
DTSTART;TZID=Europe/London:20220628T150000
DTEND;TZID=Europe/London:20220628T160000
SUMMARY:TBD
DESCRIPTION:TBD\n\nSpeaker:\n* Dr Gianmaria Falasco (University of Padova)
LOCATION:Online - see email.
URL:https://www.ph.ed.ac.uk/events/2022/82332-tbd
END:VEVENT
END:VCALENDAR