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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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BEGIN:STANDARD
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-80900@www.ph.ed.ac.uk
DTSTAMP:20210723T234101
CREATED:20200910T134851
LAST-MODIFIED:20200910T134851
STATUS:CONFIRMED
DTSTART;TZID=Europe/London:20200923T113000
DTEND;TZID=Europe/London:20200923T123000
SUMMARY:TBD
DESCRIPTION:TBD\n\nSpeaker:\n* Professor Martin Evans (School of Physics &
Astronomy\, University of Edinburgh)
LOCATION:Online - see email.
URL:https://www.ph.ed.ac.uk/events/2020/80900-tbd
END:VEVENT
BEGIN:VEVENT
CLASS:PUBLIC
UID:EVENT-80860@www.ph.ed.ac.uk
DTSTAMP:20210723T234101
CREATED:20200904T100403
LAST-MODIFIED:20200925T143710
STATUS:CONFIRMED
DTSTART;TZID=Europe/London:20200930T113000
DTEND;TZID=Europe/London:20200930T123000
SUMMARY:The many faces of the Fisher-KPP equation
DESCRIPTION:The Fisher KPP equation describes the growth of a stable regio
n into an unstable medium. It was introduced in 1937 both by the biologi
st and statistician Fisher and by the mathematicians Kolmogorov\, Petrovs
ky\, Piscounov to model the propagation of a favorable gene in a populati
on. It is one of the classical examples of the problem of velocity s
election. It also appears in many other contexts\, ranging from the
theory of disordered systems and spin glasses to reaction diffusion
problems\, branching Brownian motion and models of evolution with sel
ection. \n\nAfter a short review\, this talk will try to present severa
l recent results.\n\nSpeaker:\n* Professor Bernard Derrida (Collège de F
rance\, Paris\, France.)
LOCATION:Online - see email
URL:https://www.ph.ed.ac.uk/events/2020/80860-the-many-faces-of-the-fisher
-kpp-equation
END:VEVENT
BEGIN:VEVENT
CLASS:PUBLIC
UID:EVENT-80673@www.ph.ed.ac.uk
DTSTAMP:20210723T234101
CREATED:20200716T102332
LAST-MODIFIED:20200925T154612
STATUS:CONFIRMED
DTSTART;TZID=Europe/London:20201007T113000
DTEND;TZID=Europe/London:20201007T123000
SUMMARY:Building a path-integral calculus: a covariant discretization appr
oach
DESCRIPTION:Path integrals are a central tool when it comes to describing
quantum or thermal fluctuations of particles or fields. Their success date
s back to Feynman who showed how to use them within the framework of quant
um mechanics. Since then\, path integrals have pervaded all areas of physi
cs where fluctuation effects\, quantum and/or thermal\, are important. The
ir appeal is based on the fact that one converts a problem formulated in t
erms of operators into one of sampling classical paths with a given weight
.\n\nMany different definitions are used to define path-integral weight. I
n statistical mechanics\, time-discretization is the standard approach\; i
t implies that\, unlike conventional integrals\, path integration suffers
a serious drawback: in general\, one cannot make non-linear changes of var
iables without committing an error of some sort. In such an approach\, no
path-integral based calculus is possible. We explain which are the mathema
tical reasons causing this important caveat\, and we come up with cures fo
r systems described by one degree of freedom. Our main result is a constru
ction of path integration free of this problem\, through a direct time-dis
cretization procedure. We also compare our time-discretized approach to ot
her definitions of path-integral weights that were used in field theories
of quantum problems.\n\nSpeaker:\n* Vivien Lecomte (Université Grenoble-A
lpes\, France.)
LOCATION:Online - see email
URL:https://www.ph.ed.ac.uk/events/2020/80673-building-a-path-integral-cal
culus-a-covariant-discretization-approach
END:VEVENT
BEGIN:VEVENT
CLASS:PUBLIC
UID:EVENT-80674@www.ph.ed.ac.uk
DTSTAMP:20210723T234101
CREATED:20200716T102514
LAST-MODIFIED:20201008T094626
STATUS:CONFIRMED
DTSTART;TZID=Europe/London:20201014T113000
DTEND;TZID=Europe/London:20201014T123000
SUMMARY:First-order fluctuation-induced phase transitions to collective mo
tion
DESCRIPTION:The transition to collective motion is paradigmatic of active
matter. Self-propelled particles that stochastically align undergo a trans
ition between a disordered state\, at low density and large noise\, and an
ordered one\, at high density and low noise. In the latter phase\, part
icles travel together in a randomly selected direction of space\, hence s
pontaneously breaking its isotropy. The nature of this transition has bee
n at the center of a long-standing debate. Numerical simulations and mean
-fieldish continuous descriptions have led to the common belief that\, de
pending on the type of microscopic interactions between particles\, two t
ypes of transitions could be observed. When particles interact with their
neighbours within a finite-distance\, the transition is first order\, wi
th a coexistence phase separating the disordered gas and the ordered liqu
id. On the contrary\, when particles interact with `toplogical' neighbour
s\, the transition is believed to be continuous. In this talk I will show
how dressing mean-field hydrodynamic descriptions with noise systematica
lly lead to first-order phase transitions. This holds for metric models b
ut\, more surprisingly\, also for topological hydrodynamic theories that
retain the non-local nature of the aligning interactions at the macroscop
ic scale. These results have been confirmed using numerical simulations o
f microscopic models in which particles interact with their k nearest nei
ghbours\, a model which is claimed to be relevant for animal-behaviour st
udies. \n\nSpeaker:\n* Julien Tailleur (Université de Paris)
LOCATION:Online - see email.
URL:https://www.ph.ed.ac.uk/events/2020/80674-first-order-fluctuation-indu
ced-phase-transitions-to-collective-motion
END:VEVENT
BEGIN:VEVENT
CLASS:PUBLIC
UID:EVENT-80675@www.ph.ed.ac.uk
DTSTAMP:20210723T234101
CREATED:20200716T102705
LAST-MODIFIED:20201017T103737
STATUS:CONFIRMED
DTSTART;TZID=Europe/London:20201021T113000
DTEND;TZID=Europe/London:20201021T123000
SUMMARY:Online Seminar: Statistical mechanics foundation of Weber-Fechner
laws
DESCRIPTION:Even though the phenomenological relations between perception
and stimulus have been firmly established\, a theoretical argument for Web
er's and Fechner's law in terms of relevant models or from statistical phy
sics is largely missing. We present such a discussion in terms of response
theory for nonequilibrium systems\, where the induced displacement or cur
rent\, which stands for the perceived stimulus\, crucially depends on the
change in time-symmetric reactivities. Stationary nonequilibria may indeed
generate extra currents by changing the dynamical activity. The argument
finishes by understanding how the extra dynamical activity logarithmically
encodes the actual stimulus.\n\nSee arxiv.org/abs/2009.00923v1\n\nSpeake
r:\n* Christian Maes (University of Leuven)
LOCATION:Online - see email.
URL:https://www.ph.ed.ac.uk/events/2020/80675-online-seminar-statistical-m
echanics-foundation-of-weber-fechner-laws
END:VEVENT
BEGIN:VEVENT
CLASS:PUBLIC
UID:EVENT-80677@www.ph.ed.ac.uk
DTSTAMP:20210723T234101
CREATED:20200716T103126
LAST-MODIFIED:20201019T074529
STATUS:CONFIRMED
DTSTART;TZID=Europe/London:20201028T113000
DTEND;TZID=Europe/London:20201028T123000
SUMMARY:An exact solution for a quasi-two-dimensional exclusion process
DESCRIPTION:We consider a disordered asymmetric exclusion process with two
kinds of particles (labelled 1 and 2\, say) on a finite two-dimensional
toroidal lattice. The dynamics is controlled by particles of type 1\, whi
ch only move horizontally\, with individual hopping rates. The motion of
particles of type 2 depends on the relative position of these with resp
ect to the 1's\, and can be both horizontal and vertical. For this proces
s\, we compute the partition function\, densities and currents exactly. W
e observe a novel microscopic Scott Russell linkage phenomenon: the curre
nt of 2's in the vertical direction is the same as that of 1's in the hor
izontal direction.\n This is joint work with P. Nadeau.\n\nSpeaker:\n* Pro
fessor Arvind Ayyer (Indian Institute of Science\, Bangalore\, India)
LOCATION:Online - see email.
URL:https://www.ph.ed.ac.uk/events/2020/80677-an-exact-solution-for-a-quas
i-two-dimensional-exclusion-process
END:VEVENT
BEGIN:VEVENT
CLASS:PUBLIC
UID:EVENT-81094@www.ph.ed.ac.uk
DTSTAMP:20210723T234101
CREATED:20201031T160126
LAST-MODIFIED:20201031T160126
STATUS:CONFIRMED
DTSTART;TZID=Europe/London:20201104T113000
DTEND;TZID=Europe/London:20201104T123000
SUMMARY:Local: Kermack and McKendrick’s “Contributions to the Mathemat
ical Theory of Epidemics"
DESCRIPTION:This sequence of papers\, published in the late 1920’s\, are
credited with introducing the dominant epidemic modelling paradigm\, now
known as “compartmental models”. These have been widely used by many g
roups to make predictions for the current pandemic. I will summarise the m
odel that is introduced in this work\, before focussing on the special cas
e of the famous SIR (susceptible-infected-recovered) model. This model def
ies an exact solution\, but it is possible to determine quantities like th
e outbreak size analytically\, gain some understanding of the much-discuss
ed R number\, and also find the time-dependent solution in an approximatio
n when the outbreak is small relative to the population size. \n \n\nSp
eaker:\n* Professor Richard Blythe (School of Physics & Astronomy\, Univer
sity of Edinburgh)
LOCATION:Online-see email.
URL:https://www.ph.ed.ac.uk/events/2020/81094-local-kermack-and-mckendrick
s-contributions-to-the-mathematical-theory-of-epidemics
END:VEVENT
BEGIN:VEVENT
CLASS:PUBLIC
UID:EVENT-80826@www.ph.ed.ac.uk
DTSTAMP:20210723T234101
CREATED:20200824T094916
LAST-MODIFIED:20201104T090654
STATUS:CONFIRMED
DTSTART;TZID=Europe/London:20201111T113000
DTEND;TZID=Europe/London:20201111T123000
SUMMARY:Online seminar: Perturbations and boundaries in flocking systems
DESCRIPTION:Polar flocking is one of the simplest but at the same time ric
her examples of collective behaviour in active matter systems. Its physica
l behaviour — stemming from the spontaneous breaking of a continuous sym
metry and the nonequilibrium coupling of density and orientation fluctuati
ons — has been thoroughly investigated in the last two decades\, and we
now have a good understanding of the asymptotic behaviour of isolated syst
ems\, at least in the dry and dilute approximation.\n Considering flocks t
hat are not isolated\, but rather immersed and interacting with the extern
al world\, on the other hand\, forces one to consider the effect of bounda
ries\, surface tension and/or the response to external perturbations. Surf
ace tension\, for instance\, is needed to maintain flock cohesion\, and du
e to their non-equilibrium activity\, finite flocks exhibit faster than eq
uilibrium surface fluctuations. The information inflow from the boundary\,
moreover\, may also alter bulk correlations\, both for isolated flocks or
in the presence of an external perturbations. Asymptotic linear response
theory will also be discussed and compared with recent experimental result
s in active colloids.\n\nSpeaker:\n* Francesco Ginelli ( University of Ins
ubria\, Como\, Italy.)
LOCATION:Online - see email
URL:https://www.ph.ed.ac.uk/events/2020/80826-online-seminar-perturbations
-and-boundaries-in-flocking-systems
END:VEVENT
BEGIN:VEVENT
CLASS:PUBLIC
UID:EVENT-81000@www.ph.ed.ac.uk
DTSTAMP:20210723T234101
CREATED:20201014T092926
LAST-MODIFIED:20201104T090342
STATUS:CONFIRMED
DTSTART;TZID=Europe/London:20201118T113000
DTEND;TZID=Europe/London:20201118T123000
SUMMARY:Online Seminar: Kinetically constrained models: universality resul
ts
DESCRIPTION:Kinetically constrained models were originally introduced in
the 80's based on free volume theories of the glass transition and later
used as a paradigm model for the dynamical facilitation scenario. More re
cently\, a renewed interest comes from the study of their quantum version\
, in connection with the issue of many body localization.\n\nIn this semin
ar I will discuss some recent rigorous results on the critical time scales
of KCM when the temperature goes to zero\, as well as the connection with
the critical behavior of the corresponding deterministic bootstrap percol
ation cellular automata. In particular\, I will provide the full picture o
f the universality classes for KCM in two dimensions. \n\nSpeaker:\n* Cri
stina Toninelli (Université Paris Dauphine)
LOCATION:Online - see email.
URL:https://www.ph.ed.ac.uk/events/2020/81000-online-seminar-kinetically-c
onstrained-models-universality-results
END:VEVENT
BEGIN:VEVENT
CLASS:PUBLIC
UID:EVENT-80910@www.ph.ed.ac.uk
DTSTAMP:20210723T234101
CREATED:20200913T105330
LAST-MODIFIED:20201116T070627
STATUS:CONFIRMED
DTSTART;TZID=Europe/London:20201125T113000
DTEND;TZID=Europe/London:20201125T123000
SUMMARY:Online Seminar: Controlling active matter: From engines to biased
ensembles
DESCRIPTION:Active matter is a class of nonequilibrium systems where every
component extracts energy from its environment to produce an autonomous\,
directed motion. This directed motion yields some anomalous thermo-mechan
ical properties\, and it can lead to collective states without any equilib
rium equivalent. Many previous studies have studied in detail the phase di
agrams of active systems\, and to which extent some equations of states ca
n be drawn beyond equilibrium. Yet\, how to control optimally active matte
r\, with a view either to extracting energy from the system or to promotin
g specific collective states\, remains largely an open question. In this t
alk\, I will discuss how to exploit and control nonequilibrium properties
to (i) design innovative engines with thermodynamic cycles\, and (ii) indu
ce phase transitions in dissipation-biased ensembles.\n\nSpeaker:\n* Étie
nne Fodor (University of Luxembourg)
LOCATION:Online - see email.
URL:https://www.ph.ed.ac.uk/events/2020/80910-online-seminar-controlling-a
ctive-matter-from-engines-to-biased-ensembles
END:VEVENT
BEGIN:VEVENT
CLASS:PUBLIC
UID:EVENT-81124@www.ph.ed.ac.uk
DTSTAMP:20210723T234101
CREATED:20201112T133645
LAST-MODIFIED:20201128T112002
STATUS:CONFIRMED
DTSTART;TZID=Europe/London:20201202T113000
DTEND;TZID=Europe/London:20201202T123000
SUMMARY:Online seminar: Counting statistics for non-interacting fermions i
n a d-dimensional potential
DESCRIPTION:Over the past few decades\, there have been spectacular experi
mental developments in manipulating cold atoms (bosons or fermions) [1\, 2
]\, which allow one to probe quantum many-body physics\, both for interact
ing and noninteracting systems. In this talk we focus on the noninteractin
g Fermi gas\, for which a general theoretical framework has been developed
over the recent years [3\,4]. We consider a generic model of N non-inter
acting spinless fermions in d dimensions confined by a general trapping po
tential (we assume a central potential for d>1)\, in the ground-state. In
d=1\, for specific potentials\, this system is related to classical random
matrix ensembles. We develop a theoretical framework for studying the qua
ntum fluctuations of the number of fermions N_D in a domain D of macroscop
ic size in the bulk of the Fermi gas (in d>1 we assume that D is a spheric
al domain). We show that the variance of N_D grows as N^((d-1)/d) * (A log
(N) + B) for N>>1\, and obtain the explicit dependence of A\,B on the pote
ntial. This leads us to conjecture similar asymptotics for the entanglemen
t entropy of the subsystem D\, in any dimension\, which agrees with exact
results for d=1.\n The talk is based on the recent work [5].\n [1] I. Bloc
h\, J. Dalibard and W. Zwerger\, Rev. Mod. Phys. 80 885 (2008).\n [2] S. G
iorgini\, L. P. Pitaevski and S. Stringari\, Rev. Mod. Phys. 80 1215 (2008
).\n [3] D. S. Dean\, P. Le Doussal\, S. N. Majumdar\, G. Schehr\, Phys. R
ev. A 94\, 063622 (2016).\n [4] D. S. Dean\, P. Le Doussal\, S. N. Majumda
r\, G. Schehr\, J. Phys. A: Math. Theor. 52 144006 (2019).\n [5] N. R. Smi
th\, P. Le Doussal\, S. N. Majumdar\, G. Schehr\, arXiv:2008.01045. \n\
nSpeaker:\n* Dr. Naftali Smith (LPTMS\, CNRS\, Univ. Paris-Sud\, Universit
e Paris-Saclay\, and Ecole Normale Superieure (Paris).)
LOCATION:Online - see email.
URL:https://www.ph.ed.ac.uk/events/2020/81124-online-seminar-counting-stat
istics-for-non-interacting-fermions-in-a-d-dimensional-potential
END:VEVENT
BEGIN:VEVENT
CLASS:PUBLIC
UID:EVENT-81135@www.ph.ed.ac.uk
DTSTAMP:20210723T234101
CREATED:20201124T142740
LAST-MODIFIED:20201124T142740
STATUS:CONFIRMED
DTSTART;TZID=Europe/London:20201209T113000
DTEND;TZID=Europe/London:20201209T123000
SUMMARY:Building Continuous Time Crystals from Rare Events
DESCRIPTION:Abstract: Symmetry-breaking dynamical phase transitions (DPTs)
abound in the fluctuations of non-equilibrium systems. In this talk\, I w
ill show that the spectral features of a particular class of DPTs exhibit
the fingerprints of the recently discovered time-crystal phase of matter.
Using Doob’s transform as a tool\, I will provide a mechanism to build c
lassical time-crystal generators from the rare event statistics of some dr
iven diffusive systems. An analysis of the Doob’s smart field in terms o
f the order parameter of the transition then leads to the time-crystal lat
tice gas (TCLG)\, a model of driven fluid subject to an external packing f
ield\, which presents a clear-cut steady-state phase transition to a time-
crystalline phase characterized by a matter density wave\, which breaks co
ntinuous time-translation symmetry and displays rigidity and long-range sp
atiotemporal order\, as required for a time crystal. A hydrodynamic analys
is of the TCLG transition uncovers striking similarities\, but also key di
fferences\, with the Kuramoto synchronization transition. Possible experim
ental realizations of the TCLG in colloidal fluids will be also discussed.
\n\n\n\nSee https://journals.aps.org/prl/abstract/10.1103/PhysRevLett.125
.160601 \, also available at https://arxiv.org/abs/1912.02733.\n\nSpeake
r:\n* Dr. Carlos Perez Espigares (Universidad de Granada\, Spain)
LOCATION:Online - see email.
URL:https://www.ph.ed.ac.uk/events/2020/81135-building-continuous-time-cry
stals-from-rare-events
END:VEVENT
BEGIN:VEVENT
CLASS:PUBLIC
UID:EVENT-81125@www.ph.ed.ac.uk
DTSTAMP:20210723T234101
CREATED:20201113T140928
LAST-MODIFIED:20201210T085818
STATUS:CONFIRMED
DTSTART;TZID=Europe/London:20201216T113000
DTEND;TZID=Europe/London:20201216T123000
SUMMARY:Inhomogeneous exclusion processes and the efficiency of translatio
n
DESCRIPTION:Motivated by recent experiments on an antibiotic resistance ge
ne\, we investigate genetic interactions between synonymous mutations in
the framework of exclusion models of translation. We show that the ran
ge of possible interactions is markedly different depending on whether tr
anslation efficiency is assumed to be proportional to ribosome current o
r ribosome speed. In the first case every mutational effect has a definit
e sign that is independent of genetic background\, whereas in the second
case the effect-sign can vary depending on the presence of other muta
tions. The latter result is demonstrated using configurations of multiple
translational bottlenecks induced by slow codons.\n\nSpeaker:\n* Professo
r Joachim Krug (Institute for Biological Physics\, University of Cologne)
LOCATION:Online - see email.
URL:https://www.ph.ed.ac.uk/events/2020/81125-inhomogeneous-exclusion-proc
esses-and-the-efficiency-of-translation
END:VEVENT
BEGIN:VEVENT
CLASS:PUBLIC
UID:EVENT-81031@www.ph.ed.ac.uk
DTSTAMP:20210723T234101
CREATED:20201020T142612
LAST-MODIFIED:20210107T155502
STATUS:CONFIRMED
DTSTART;TZID=Europe/London:20210113T113000
DTEND;TZID=Europe/London:20210113T123000
SUMMARY:Active Brownian motion in two-dimensions under stochastic resettin
g
DESCRIPTION:We study the position distribution of an active Brownian parti
cle (ABP) in the presence of\n stochastic resetting in two spatial dimensi
ons. We consider three different resetting protocols : (I)\n where both po
sition and orientation of the particle are reset\, (II) where only the pos
ition is reset\,\n and (III) where only the orientation is reset with a ce
rtain rate r. We show that in the first two cases\n the ABP reaches a stat
ionary state. Using a renewal approach\, we calculate exactly the stationa
ry\n marginal position distributions in the limiting cases when the resett
ing rate r is much larger or\n much smaller than the rotational diffusion
constant D R of the ABP. We find that\, in some cases\,\n for a large rese
tting rate\, the position distribution diverges near the resetting point\;
the nature of\n the divergence depends on the specific protocol. For the
orientation resetting\, there is no stationary\n state\, but the motion ch
anges from a ballistic one at short-times to a diffusive one at late times
.\n We characterize the short-time non-Gaussian marginal position distribu
tions using a perturbative\n approach.\n\nSpeaker:\n* Dr Urna Basu (S. N.
Bose National Centre for Basic Sciences\, Kolkata\, India.)
LOCATION:Online - see email.
URL:https://www.ph.ed.ac.uk/events/2021/81031-active-brownian-motion-in-tw
o-dimensions-under-stochastic-resetting
END:VEVENT
BEGIN:VEVENT
CLASS:PUBLIC
UID:EVENT-81014@www.ph.ed.ac.uk
DTSTAMP:20210723T234101
CREATED:20201015T103957
LAST-MODIFIED:20201015T103957
STATUS:CONFIRMED
DTSTART;TZID=Europe/London:20210120T113000
DTEND;TZID=Europe/London:20210120T123000
SUMMARY:Modeling of collective effects in human or molecular pedestrian fl
ows
DESCRIPTION:Designing buildings\, cities\, or video games\, requires to un
derstand how pedestrians move. However\, modeling their motion is not so
obvious. In a first part\, we shall see how experiments can teach us abo
ut the interactions between pedestrians and guide us for the development
of new models at low\, intermediate\, or high densities.\n In a second pa
rt\, we shall change scale\, and consider the molecular pedestrians respo
nsible for transport inside our cells. We will try to understand which ru
les they obey\, and why the cell sometimes uses very counter intuitive so
lutions to organize this transport.\n\nSpeaker:\n* Dr Cecile Appert-Rollan
d
LOCATION:Online - see email.
URL:https://www.ph.ed.ac.uk/events/2021/81014-modeling-of-collective-effec
ts-in-human-or-molecular-pedestrian-flows
END:VEVENT
BEGIN:VEVENT
CLASS:PUBLIC
UID:EVENT-81163@www.ph.ed.ac.uk
DTSTAMP:20210723T234101
CREATED:20201207T162639
LAST-MODIFIED:20210119T161219
STATUS:CONFIRMED
DTSTART;TZID=Europe/London:20210127T113000
DTEND;TZID=Europe/London:20210127T123000
SUMMARY:Universal survival probability for a d-dimensional run-and-tumble
particle
DESCRIPTION:We consider an active run-and-tumble particle (RTP) in d dimen
sions and compute exactly the probability S(t) that the x-component of th
e position of the RTP does not change sign up to time t. When the tumbli
ngs occur at a constant rate\, we show that S(t) is independent of d for
any finite time t (and not just for large t)\, as a consequence of the ce
lebrated Sparre Andersen theorem for discrete-time random walks in one di
mension. Moreover\, we show that this universal result holds for a much w
ider class of RTP models in which the speed v of the particle after each
tumbling is random\, drawn from an arbitrary probability distribution. We
further demonstrate\, as a consequence\, the universality of the record
statistics in the RTP problem.\n\nSpeaker:\n* Satya Majumdar (Université
de Paris-Sud)
LOCATION:Online - see email
URL:https://www.ph.ed.ac.uk/events/2021/81163-universal-survival-probabili
ty-for-a-d-dimensional-run-and-tumble-particle
END:VEVENT
BEGIN:VEVENT
CLASS:PUBLIC
UID:EVENT-81183@www.ph.ed.ac.uk
DTSTAMP:20210723T234101
CREATED:20201217T131615
LAST-MODIFIED:20210128T121917
STATUS:CONFIRMED
DTSTART;TZID=Europe/London:20210203T113000
DTEND;TZID=Europe/London:20210203T123000
SUMMARY:Stochastic Chemical Reaction Networks
DESCRIPTION:The study of chemical reaction networks (CRN's) is a very acti
ve field. Earlier well-known results (Feinberg Chem. Enc. Sci. 42 2229 (19
87)\, Anderson et al Bull. Math. Biol. 72 1947 (2010) ) identify a topolog
ical quantity called deficiency\, for any CRN\, which\, when exactly equal
to zero\, leads to a unique factorized steady-state for these networks. N
o general results exist however for the steady states of non-zero-deficien
cy networks. In this paper\, we show how to write the full moment-hierarch
y for any non-zero-deficiency CRN obeying mass-action kinetics\, in terms
of equations for the factorial moments. Using these\, we can recursively p
redict values for lower moments from higher moments\, reversing the proced
ure usually used to solve moment hierarchies. We show\, for non-trivial ex
amples\, that in this manner we can predict any moment of interest\, for C
RN's with non-zero deficiency and non-factorizable steady states.\n\nSpeak
er:\n* Supriya Krishnamurthy (Fysikum\, Stockholm University)
LOCATION:Online - see email
URL:https://www.ph.ed.ac.uk/events/2021/81183-stochastic-chemical-reaction
-networks
END:VEVENT
BEGIN:VEVENT
CLASS:PUBLIC
UID:EVENT-81112@www.ph.ed.ac.uk
DTSTAMP:20210723T234101
CREATED:20201111T181039
LAST-MODIFIED:20210201T104907
STATUS:CONFIRMED
DTSTART;TZID=Europe/London:20210210T113000
DTEND;TZID=Europe/London:20210210T123000
SUMMARY:Analysing quantum large deviations using classical (unravelled) st
ochastic processes
DESCRIPTION:An important class of non-equilibrium quantum systems can be d
escribed by Markovian models\, using the Lindblad formalism. For example
\, one can consider an atom with a few quantum states\, absorbing energy f
rom a laser\, and emitting photons into its environment. In this case\,
the sequences of emitted photons are random\; their behaviour can be captu
red by a stochastic process for the system wavefunction (or a pure-state d
ensity matrix). Such stochastic processes can be analysed by the methods
of classical probability : I will present a level-2.5 description of thei
r large deviations [1\,2]. This provides a detailed description of the j
oint fluctuations of the system and the emitted photons. Examples includ
e quantum reset processes\, for which this method yields an uncertainty re
lation between the mean and variance of the photon counts [1]. The metho
d can be extended to systems under continuous (weak) measurement\, using t
he theory of quantum state diffusion [2].\n [1] F Carollo\, RL Jack\, and
JP Garrahan\, Phys. Rev. Lett. 122\, 130605 (2019)\n [2] F Carollo\, JP Ga
rrahan\, and RL Jack\, arXiv:2101.04138\n \n\nSpeaker:\n* Robert Jack (D
AMTP\, Cambridge)
LOCATION:Online - see email.
URL:https://www.ph.ed.ac.uk/events/2021/81112-analysing-quantum-large-devi
ations-using-classical-unravelled-stochastic-processes
END:VEVENT
BEGIN:VEVENT
CLASS:PUBLIC
UID:EVENT-81162@www.ph.ed.ac.uk
DTSTAMP:20210723T234101
CREATED:20201207T162441
LAST-MODIFIED:20210119T161054
STATUS:CONFIRMED
DTSTART;TZID=Europe/London:20210217T113000
DTEND;TZID=Europe/London:20210217T123000
SUMMARY:Simulation of extremely rare ultra-fast non-equilibrium processes
close to equilibrium
DESCRIPTION:Work theorems like Crooks equation allow to obtain equilibrium
quantities from non-equilibrium processes. A standard setup is starting
a system in contact to a heat bath in equilibrium\, then executing a pro
cess by changing some external parameter which leads to performing work\,
and ending in some non-equilibrium configuration. The distribution P(W)
of the work allows to extract the free energy difference \\Delta F betwee
n equilibrium starting state and the imaginary final equilibrium state\,
which would be obtained if one waited long enough after the process has b
een finished. The region of P(W) which is most relevant to obtain \\Delta
F is where W is about \\Delta F. Nevertheless\, if the investigate
d system is not too small\, P(W) will be tiny\, like 10^{-15} or smaller
(decreasing with increasing system size) being located in the rare-event
tail. Thus\, when studying such processes by simulation\, one needs to us
e large-deviation approaches applied to the dynamic evolution of the resp
ective model.\n Here we will investigate the question how similar non-eq
uilibrium processes are to the equilibrium ones beyond comparing a scalar
number like the work. Still\, we study this question as a function of th
e measured work W. For that purpose we investigate numerically the unf
olding and refolding of RNA secondary structures under influence of an ex
ternal force f. Fortunately\, for this model the equilibrium behavior can
be accessed exactly by dynamic programming algorithms allowing to sample
equilibrium unfolding and folding processes. We compare between equilib
rium and non-equilibrium dynamics by means of force-extension curves n(f)
and overlap profiles \\sigma(f). Our results indicate that indeed the ex
treme low-probability trajectories which exhibit W near \\Delta F\, and t
hus contribute most to the determination of \\Delta F via Crooks equation
\, are most similar to the equilibrium trajectories.\n\nSpeaker:\n* Prof.
Dr. Alexander Hartmann (Universität Oldenburg\, Institut für Physik)
LOCATION:Online - see email
URL:https://www.ph.ed.ac.uk/events/2021/81162-simulation-of-extremely-rare
-ultra-fast-non-equilibrium-processes-close-to-equilibrium
END:VEVENT
BEGIN:VEVENT
CLASS:PUBLIC
UID:EVENT-81294@www.ph.ed.ac.uk
DTSTAMP:20210723T234101
CREATED:20210214T163621
LAST-MODIFIED:20210222T130249
STATUS:CONFIRMED
DTSTART;TZID=Europe/London:20210224T103000
DTEND;TZID=Europe/London:20210224T113000
SUMMARY:[Note: starting time 10.30] Biophysical principles underlying chro
mosome organisation and transcription
DESCRIPTION:I will describe two biophysical mechanisms underlying chromoso
me organisation which we and others have recently worked on. The first mec
hanism - the bridging-induced attraction - drives intranuclear phase separ
ation (more precisely microphase separation) of DNA-binding proteins. The
other mechanism - loop extrusion - is responsible for the formation of non
equilibrium chromosome loops.\n\nI will also discuss some recent work we h
ave done which aims to find the functional role of microphase separation
in transcription. Specifically I will show how our modelling can be used
to study the dynamics of chromatin transcription\, and to quantitatively p
redict the effect of 3D structure on transcriptional activity in human cel
ls.\n\nSpeaker:\n* Professor Davide Marenduzzo (School of Physics & Astron
omy\, University of Edinburgh)
LOCATION:Online - see email
URL:https://www.ph.ed.ac.uk/events/2021/81294-note-starting-time-1030-biop
hysical-principles-underlying-chromosome-organisation-and-transcription
END:VEVENT
BEGIN:VEVENT
CLASS:PUBLIC
UID:EVENT-81285@www.ph.ed.ac.uk
DTSTAMP:20210723T234101
CREATED:20210211T153739
LAST-MODIFIED:20210216T135308
STATUS:CONFIRMED
DTSTART;TZID=Europe/London:20210303T113000
DTEND;TZID=Europe/London:20210303T123000
SUMMARY:Large Deviations at Level 2.5 for Random Walks in Random Media
DESCRIPTION:For Markov processes converging towards non-equilibrium steady
-states\, the large deviations at Level 2.5 characterize the joint distri
bution of the time-averaged density and of the time-averaged flows that c
an be seen in a long dynamical trajectory. After a brief introduction\, t
his general framework will be illustrated with three examples of one-dimen
sional disordered models:\n\n(i) the Sinai Random Walk on a ring\, where e
ach site has its own probabilities to induce the next jump to the right or
to the left \n\n(ii) the Directed Trap model on a ring\, where each site
has its own trapping time\n\n(iii) the Sisyphus process in a random lands
cape\, where each position has its own reset rate towards the origin\n\nSp
eaker:\n* Cécile Monthus (CNRS\, CEA\, Université Paris Saclay)
LOCATION:Online - see email
URL:https://www.ph.ed.ac.uk/events/2021/81285-large-deviations-at-level-25
-for-random-walks-in-random-media
END:VEVENT
BEGIN:VEVENT
CLASS:PUBLIC
UID:EVENT-81350@www.ph.ed.ac.uk
DTSTAMP:20210723T234101
CREATED:20210226T113239
LAST-MODIFIED:20210226T113239
STATUS:CONFIRMED
DTSTART;TZID=Europe/London:20210310T113000
DTEND;TZID=Europe/London:20210310T123000
SUMMARY:Finite-time Landauer principle
DESCRIPTION:We use optimal transport theory to minimize the thermodynamic
cost associated with the erasure of a bit. In this way\, we generalise Lan
dauer's principle to erasure over a finite amount of time. Furthermore\, w
e discuss its generalisation to erasure with a finite erasure error and we
will look at special protocols such as majority-logic decoding\n\nSpeaker
:\n* Karel Proesmans (University of Luxembourg)
LOCATION:Online - see email
URL:https://www.ph.ed.ac.uk/events/2021/81350-finite-time-landauer-princip
le
END:VEVENT
BEGIN:VEVENT
CLASS:PUBLIC
UID:EVENT-80911@www.ph.ed.ac.uk
DTSTAMP:20210723T234101
CREATED:20200913T105552
LAST-MODIFIED:20210307T123912
STATUS:CONFIRMED
DTSTART;TZID=Europe/London:20210317T113000
DTEND;TZID=Europe/London:20210317T123000
SUMMARY:Informatic versus Thermodynamic Entropy Production in Active Syste
ms
DESCRIPTION:Stochastic thermodynamics connects the steady-state entropy pr
oduction rate (EPR) of a system connected to a heat bath with the log rati
o of probabilities of forward and time-reversed trajectories. Extending th
e resulting formula to coarse-grained models of systems much further from
equilibrium\, such as schools of fish or herds of wildebeest\, results in
an informatic EPR (IEPR) that depends only on order parameter dynamics and
no longer is connected with microscopic heat flow\, but remains a valuabl
e quantifier of macroscopic irreversibility. I will discuss where the conn
ection with heat flow gets lost\, and the ambiguities caused by its absenc
e. I will also consider cases where the same coarse-grained models describ
e more microscopic processes (such as motors moving along filaments in the
cytoskeleton) for which a connection to heat flow should be recoverable.
To achieve this we can embed thecoarse-grained model into a larger model i
nvolving explicit (if schematic) chemical reactions such that the whole sy
stem is governed by linear irreversible thermodynamics -- which applies wh
enever fluxes are linear in thermodynamic forces. (It does not require tho
se forces to be linear in order parameters\, so the full nonlinearity of t
he coarse grained active model is retained.) All the active terms in the o
rder parameter dynamics then become off-diagonal elements of an Onsager ma
trix whose symmetry determines the remaining chemical couplings and thus t
he overall heat production. This exceeds the IEPR by a term that is a larg
e constant in uniform systems\, but contains additional spatial informatio
n in nonuniform ones.\n\nSpeaker:\n* Professor Michael Cates (DAMTP\, Camb
ridge)
URL:https://www.ph.ed.ac.uk/events/2021/80911-informatic-versus-thermodyna
mic-entropy-production-in-active-systems
END:VEVENT
BEGIN:VEVENT
CLASS:PUBLIC
UID:EVENT-81336@www.ph.ed.ac.uk
DTSTAMP:20210723T234101
CREATED:20210225T181403
LAST-MODIFIED:20210225T181403
STATUS:CONFIRMED
DTSTART;TZID=Europe/London:20210324T113000
DTEND;TZID=Europe/London:20210324T123000
SUMMARY:Non-equilibrium dynamics of exactly solvable cellular automata
DESCRIPTION:In both classical and quantum non-equilibrium there is curren
tly much interest in systems with constrained dynamics. I will consider o
ne class of such problems\, that of deterministic classical cellular auto
mata\, specifically the so-called Rules 54\, 201 and 150 CAs. These corre
spond to discrete time and deterministic counterparts of stochastic latti
ce systems often studied in the context of glasses or of Rydberg atoms\,
specifically the Fredrickson-Andersen\, the PXP\, and the XOR-FA kinetica
lly constrained models. I will show how these CAs are integrable and how
many properties of their dynamics can be computed exactly using matrix pr
oduct states\, including non-equilibrium steady\n states\, time-correlator
s and dynamical large deviations.\n \n\nSpeaker:\n* Juan P. Garrahan (Un
iversity of Nottingham )
LOCATION:Online - see email
URL:https://www.ph.ed.ac.uk/events/2021/81336-non-equilibrium-dynamics-of-
exactly-solvable-cellular-automata
END:VEVENT
BEGIN:VEVENT
CLASS:PUBLIC
UID:EVENT-81283@www.ph.ed.ac.uk
DTSTAMP:20210723T234101
CREATED:20210208T201842
LAST-MODIFIED:20210326T121556
STATUS:CONFIRMED
DTSTART;TZID=Europe/London:20210331T113000
DTEND;TZID=Europe/London:20210331T123000
SUMMARY:Phase separation in active systems: field theoretical description
DESCRIPTION:Active particles extract energy from the environment and dissi
pate it to self-propel. One of their notable self-organizing phenomenologi
es is phase separation into dense (liquid) and dilute (vapor) regions\, wh
ich happens even for purely repulsive units. This phenomena\, although gen
erically happening far-from-equilibrium\, was first described via an appro
ximate mapping onto equilibrium liquid-vapor phase separation.\n\nRecently
it has become clear\, however\, that phase separation in active systems g
enerically displays strongly non-equilibrium features. In experiments\, ph
ase separation is often arrested to a finite length-scale (micro-phase sep
aration). Active systems can undergo bubbly phase separation\, where a see
mingly boiling liquid coexists with a vapour region\, and even more comple
x forms of phase separation have been observed experimentally. \n\nI will
describe our recent efforts to describe phase separation in active matter
and\, more generally\, in systems where detailed balance is broken locall
y. These results will be investigated via field-theoretical analysis\, ex
tending Model B to include the leading-order terms that break detailed bal
ance (Active Model B+). This allowed to rationalize microphase separation
\, of either liquid droplets or vapour bubbles\, and bubbly phase separati
on via a generic mechanism: the fact that at high activity Ostwald ripenin
g can go into reverse. We further discover that activity can cause an inst
ability of the liquid-vapor interface\, giving rise to another form of act
ive phase separation resembling to active foam states. Simulations of part
icle models further strengthen the figure. \n\nSpeaker:\n* Cesare Nardini
( CEA-Saclay\, France)
LOCATION:Online - see email
URL:https://www.ph.ed.ac.uk/events/2021/81283-phase-separation-in-active-s
ystems-field-theoretical-description
END:VEVENT
BEGIN:VEVENT
CLASS:PUBLIC
UID:EVENT-81296@www.ph.ed.ac.uk
DTSTAMP:20210723T234101
CREATED:20210214T164140
LAST-MODIFIED:20210331T142520
STATUS:CONFIRMED
DTSTART;TZID=Europe/London:20210407T113000
DTEND;TZID=Europe/London:20210407T123000
SUMMARY:Macroscopic description of confined particles with repulsive inter
action in equilibrium
DESCRIPTION:Systems of interacting particles confined in external potentia
ls are ubiquitous in nature. Particularly\, pairwise repulsive interactio
ns with power-law singularities have taken a special place in physics and
mathematics. I will discuss properties of a class of N particles interac
ting via pairwise repulsive interaction potential and confined by an exte
rnal potential which tries to pull them to its minimum. On the other hand
the repulsive interaction and the entropy try to spread them apart forcin
g them to settle down over some region with an inhomogeneous density. I w
ill discuss how the large-N macroscopic description of the system in term
s of this density depends on the nature and range of the repulsive intera
ction\, form of the confining potential and external constraints\, and ho
w the mean density of particles get affected by these factors.\n\nSpeaker:
\n* Anupam Kundu (International centre for theoretical sciences\, Bangalor
e)
LOCATION:Online - see email
URL:https://www.ph.ed.ac.uk/events/2021/81296-macroscopic-description-of-c
onfined-particles-with-repulsive-interaction-in-equilibrium
END:VEVENT
BEGIN:VEVENT
CLASS:PUBLIC
UID:EVENT-81328@www.ph.ed.ac.uk
DTSTAMP:20210723T234101
CREATED:20210224T164833
LAST-MODIFIED:20210401T133906
STATUS:CONFIRMED
DTSTART;TZID=Europe/London:20210414T113000
DTEND;TZID=Europe/London:20210414T123000
SUMMARY:Kardar-Parisi-Zhang universality in 1D exciton-polariton systems
DESCRIPTION:Exciton-polaritons are bosonic short-lived quasiparticles whic
h are created in a semiconductor quantum well under optical pumping\, w
here they arise from the strong-coupling of excitons (electron-hole excita
tions) and of the photons trapped in the micro-cavity. They behave collec
tively as a quantum fluid\, which is genuinely out-of-equilibrium becaus
e of its driven-dissipative nature. They were shown to exhibit the non-
equilibrium analogue of a Bose-Einstein condensation\, where a large fract
ion of the bosons condense into a single quantum state. Recently\, an une
xpected connection has been unveiled between the statistical properties of
the phase of the one-dimensional exciton-polariton condensate and the on
es of a stochastically growing interface\, described by the Kardar-Paris
i-Zhang (KPZ) equation. In this talk\, I will further explore this connec
tion\, and show that it extends well beyond the mere KPZ scaling exponents
. I will study in details the statistics of the fluctuations of the phase
of the condensate\, and show that by tailoring an appropriate confinement
potential for the polaritons\, different geometrical universality sub-cl
asses\, well-known for the KPZ interface\, can be realized in this system.
I will show in particular that the fluctuations of the phase follow the
expected Tracy-Widom GOE\, or GUE distributions\, and that their two-poin
t correlations follow the corresponding Airy processes. These results are
based on numerical simulations of the generalized Gross-Pitaevskii equati
on describing the exciton-polariton condensate with realistic experimental
parameters\, indicating that all the KPZ features are indeed observable i
n current experimental set-ups.\n \n\nSpeaker:\n* Prof Leonie Canet (Uni
versity Grenoble Alpes)
LOCATION:Online - see email
URL:https://www.ph.ed.ac.uk/events/2021/81328-kardar-parisi-zhang-universa
lity-in-1d-exciton-polariton-systems
END:VEVENT
BEGIN:VEVENT
CLASS:PUBLIC
UID:EVENT-81168@www.ph.ed.ac.uk
DTSTAMP:20210723T234101
CREATED:20201210T164758
LAST-MODIFIED:20210413T155247
STATUS:CONFIRMED
DTSTART;TZID=Europe/London:20210421T113000
DTEND;TZID=Europe/London:20210421T123000
SUMMARY:Population Dynamics in a Changing Environment: Random versus Perio
dic Switching
DESCRIPTION:Environmental changes greatly influence the evolution of popul
ations. Here\, we study the dynamics of a population of two strains\, one
growing slightly faster than the other\, competing for resources in a time
-varying binary environment modeled by a carrying capacity switching eithe
r randomly or periodically between states of abundance and scarcity. The p
opulation dynamics is characterized by demographic noise (birth and death
events) coupled to a varying environment. We elucidate the similarities an
d differences of the evolution subject to a stochastically and periodicall
y varying environment. Importantly\, the population size distribution is g
enerally found to be broader under intermediate and fast random switching
than under periodic variations\, which results in markedly different asymp
totic behaviors between the fixation probability of random and periodic sw
itching. We also determine the detailed conditions under which the fixatio
n probability of the slow strain is maximal.\n\nRelevant Publications:\n\n
1. Ami Taitelbaum\, Robert West\, Michael Assaf\, and Mauro Mobilia\, „P
opulation Dynamics in a Changing Environment: Random versus Periodic Switc
hing “\, Phys. Rev. Lett. 125\, 048105 (2020)\n\n2. Karl Wienand\, Erwin
Frey\, and Mauro Mobilia\, „Evolution of a Fluctuating Population in a
Randomly Switching Environment “\, Phys. Rev. Lett. 119\, 158301 (2017)\
n\nSpeaker:\n* Michael Assaf (The Racah Institute of Physics)
LOCATION:Online - see email
URL:https://www.ph.ed.ac.uk/events/2021/81168-population-dynamics-in-a-cha
nging-environment-random-versus-periodic-switching
END:VEVENT
BEGIN:VEVENT
CLASS:PUBLIC
UID:EVENT-81286@www.ph.ed.ac.uk
DTSTAMP:20210723T234101
CREATED:20210211T154516
LAST-MODIFIED:20210427T154514
STATUS:CANCELLED
DTSTART;TZID=Europe/London:20210428T113000
DTEND;TZID=Europe/London:20210428T123000
SUMMARY:[CANCELLED] Hydrodynamic interactions induce microphase separation
in active systems
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-induc
ed phase separation\, while in wet active matter\, the same role is played
by 'bacterial turbulence' - large-scale collective motion of a dilute su
spension of motile organisms.\n In this talk we introduce a model that sim
ultaneously includes long-range hydrodynamic interactions between microswi
mmers and microscopic ingredients necessary for the formation of motility
-induced clusters. We demonstrate that the model yields a variety of new
phases. Most importantly\, we find that the growth of motility-induced clu
sters is arrested by hydrodynamic interactions leading to microphase sepa
ration. We discuss its mechanism and propose a phase diagram for such syst
ems.\n\nSpeaker:\n* Professor Alexander Morozov (School of Physics & Astro
nomy\, University of Edinburgh)
LOCATION:Online - see email
URL:https://www.ph.ed.ac.uk/events/2021/81286-hydrodynamic-interactions-in
duce-microphase-separation-in-active-systems
END:VEVENT
BEGIN:VEVENT
CLASS:PUBLIC
UID:EVENT-81567@www.ph.ed.ac.uk
DTSTAMP:20210723T234101
CREATED:20210426T181416
LAST-MODIFIED:20210426T181647
STATUS:CONFIRMED
DTSTART;TZID=Europe/London:20210505T113000
DTEND;TZID=Europe/London:20210505T123000
SUMMARY:RNA Polymerase interactions and elongation rate
DESCRIPTION:We show that non-steric molecular interactions between RNA po
lymerase (RNAP) motors that move simultaneously on the same DNA track det
ermine strongly the kinetics of transcription elongation. With a focus on
the role of collisions and cooperation\, we introduce a stochastic model
that allows for the exact analytical computation of the stationary prope
rties of transcription elongation. This models explains the origin of the
experimentally observed effect of cooperative pushing. This enhancement
of the average RNAP velocity and elongation rate\, is shown to require a
molecular repulsion beyond steric hindrance and in excess of a critical s
trength. It persists up to a critical RNAP density above which jamming du
e to mutual blocking takes over. Surprisingly\, for strong repulsion and
at the same time strong stochastic blocking\, cooperative pushing is su
ppressed at low RNAP densities but a reentrance regime at intermediate de
nsities appears. For a simpler model we report density anticorrelations a
long the track that arise from slow transcription sites.\n\nV. Belitsky a
nd G.M. Schütz\, J. Theor. Biol.\, 462:370-380 (2019) \n\nSpeaker:\n* G
unter M. Schütz (Institute of Biological Information Processing\, Forschu
ngszentrum Jülich )
LOCATION:Online - see email
URL:https://www.ph.ed.ac.uk/events/2021/81567-rna-polymerase-interactions-
and-elongation-rate
END:VEVENT
BEGIN:VEVENT
CLASS:PUBLIC
UID:EVENT-81577@www.ph.ed.ac.uk
DTSTAMP:20210723T234101
CREATED:20210430T095332
LAST-MODIFIED:20210430T095332
STATUS:CONFIRMED
DTSTART;TZID=Europe/London:20210512T113000
DTEND;TZID=Europe/London:20210512T123000
SUMMARY:Collective phenomena in oscillator networks
DESCRIPTION:It is well known that ensembles of oscillators exhibit differe
nt collective properties\, the simplest form being the synchronization de
scribed by the Kuramoto model. In some setups\, the "macroscopic" phase i
s characterized by its own non-trivial dynamics whose relationship with t
he "microscopic" evolution of the single oscillators is far from being un
derstood. I'll go through a series of models to discuss the role of vario
us ingredients\, including heterogeneity\, the dynamical complexity of th
e single oscillators\, and the presence of inhibitory/excitatory coupling
. A special attention will be devoted to neuronal type of networks.\n\nSp
eaker:\n* Professor Antonio Politi (University of Aberdeen)
LOCATION:Online - see email.
URL:https://www.ph.ed.ac.uk/events/2021/81577-collective-phenomena-in-osci
llator-networks
END:VEVENT
BEGIN:VEVENT
CLASS:PUBLIC
UID:EVENT-81569@www.ph.ed.ac.uk
DTSTAMP:20210723T234101
CREATED:20210427T101026
LAST-MODIFIED:20210505T094441
STATUS:CONFIRMED
DTSTART;TZID=Europe/London:20210519T113000
DTEND;TZID=Europe/London:20210519T123000
SUMMARY:Eco-evolutionary dynamics of a fluctuating population in a switchi
ng environment
DESCRIPTION:Environmental variability greatly influences how the size and
composition of a population evolve\, i.e. its eco-evolutionary dynamics. I
n this talk\, I will consider a population of finite and fluctuating size
whose growth is limited by a binary carrying capacity switching either ran
domly or periodically in time. This models environmental changes between s
tates of resources abundance and scarcity. The population consists of two
strains\, one slightly faster than the other\, competing under two scenari
os: one in which competition is solely for resources\, and another one in
which the slow ("cooperating") strain produces a public good. I will discu
ss how the coupling of demographic noise with environmental variability af
fects the population's eco-evolutionary dynamics. In particular\, we will
see how the population size distribution and the fixation probability of t
he slow/cooperative strain are influenced by environmental variability. In
the simple model of resource competition these features will be analysed
by stressing the similarities and differences of the evolution subject to
a randomly/periodically switching environment. In the context of the publi
c good scenario\, I will address the question of when it is best to cooper
ate in a randomly switching environment. If time permits\, I will also out
line new survival scenarios arising in rock-paper-scissors games in popula
tions of fluctuating size.\n\nSpeaker:\n* Associate Professor Mauro Mobili
a (University of Leeds)
LOCATION:Online - see email.
URL:https://www.ph.ed.ac.uk/events/2021/81569-eco-evolutionary-dynamics-of
-a-fluctuating-population-in-a-switching-environment
END:VEVENT
BEGIN:VEVENT
CLASS:PUBLIC
UID:EVENT-81582@www.ph.ed.ac.uk
DTSTAMP:20210723T234101
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:20210723T234101
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:20210723T234101
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:20210723T234101
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:20210723T234101
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
END:VCALENDAR