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X-WR-CALNAME:Statistical Physics and Complexity Group meeting
X-WR-CALDESC:Statistical Physics and Complexity Group meeting
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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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TZOFFSETTO:+0000
DTSTART:19961027T020000
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BEGIN:VEVENT
CLASS:PUBLIC
UID:EVENT-79995@www.ph.ed.ac.uk
DTSTAMP:20210224T210121
CREATED:20200220T173156
LAST-MODIFIED:20200220T173156
STATUS:CONFIRMED
DTSTART;TZID=Europe/London:20200226T113000
DTEND;TZID=Europe/London:20200226T123000
SUMMARY:First passage times for (persistent) random walkers: a mystery
DESCRIPTION:A random walker hops between sites of a lattice\, choosing a n
ew direction at each hop. A persistent random walker has a memory of its h
opping direction\, so the same direction may be used for multiple hops. In
both cases we can ask how long it takes for a particle to fall off the ed
ge of finite lattice: this defines a first passage problem. We find that t
he mean first-passage time\, starting from an edge of the lattice\, is the
same for a random walker and a persistent walker. This implies that rate
at which a persistent walker changes direction does not enter into this fi
rst-passage time. The reason why is (at present) a mystery\; with perhaps
a walker that interpolates between these two behaviours shedding some ligh
t (or not) on it...\n\nSpeaker:\n* Professor Richard Blythe (School of Phy
sics & Astronomy\, University of Edinburgh)
LOCATION:Room 2511\, JCMB
URL:https://www.ph.ed.ac.uk/events/2020/79995-first-passage-times-for-pers
istent-random-walkers-a-mystery
END:VEVENT
BEGIN:VEVENT
CLASS:PUBLIC
UID:EVENT-79966@www.ph.ed.ac.uk
DTSTAMP:20210224T210121
CREATED:20200131T170846
LAST-MODIFIED:20200227T093134
STATUS:CONFIRMED
DTSTART;TZID=Europe/London:20200318T113000
DTEND;TZID=Europe/London:20200318T123000
SUMMARY:Current fluctuations in reset and run-and-tumble processes
DESCRIPTION:I will present work on current fluctuations in stochastic pro
cesses with resetting\, demonstrating in particular how phase transitions
in the large deviations can be understood via a mapping to the classic P
oland-Scheraga model for DNA denaturation [R. J. Harris and H. Touchette\
, J. Phys. A: Math. Theor. 50\, 10LT01 (2017)]. This approach can be ex
tended to treat the case where the dynamics between resets depends on the
value of a parameter fixed at the last reset and\, in this context\, I wi
ll briefly discuss the application to run-and-tumble models of bacterial
dynamics. Finally\, I will mention the recent development of a "Thermodyna
mic Uncertainty Relation" which applies for such run-and-tumble–type pr
ocesses [M. Shreshtha and R. J. Harris\, EPL (Europhysics Letters) 126\,
40007 (2019)].\n\nSpeaker:\n* Dr Rosemary Harris (Queen Mary University of
London)
LOCATION:Room 2511\, JCMB
URL:https://www.ph.ed.ac.uk/events/2020/79966-current-fluctuations-in-rese
t-and-run-and-tumble-processes
END:VEVENT
BEGIN:VEVENT
CLASS:PUBLIC
UID:EVENT-79964@www.ph.ed.ac.uk
DTSTAMP:20210224T210121
CREATED:20200131T170508
LAST-MODIFIED:20200131T170508
STATUS:CONFIRMED
DTSTART;TZID=Europe/London:20200401T113000
DTEND;TZID=Europe/London:20200401T123000
SUMMARY:TBA
DESCRIPTION:TBA\n\nSpeaker:\n* Dr Ludovic Berthier (Universite de Montpell
ier)
LOCATION:Room 2511\, JCMB
URL:https://www.ph.ed.ac.uk/events/2020/79964-tba
END:VEVENT
BEGIN:VEVENT
CLASS:PUBLIC
UID:EVENT-80085@www.ph.ed.ac.uk
DTSTAMP:20210224T210121
CREATED:20200406T092105
LAST-MODIFIED:20200406T092105
STATUS:CONFIRMED
DTSTART;TZID=Europe/London:20200408T113000
DTEND;TZID=Europe/London:20200408T123000
SUMMARY:Current fluctuations in reset and run-and-tumble processes
DESCRIPTION:I will present work on current fluctuations in stochastic\n pr
ocesses with resetting\, demonstrating in particular how phase\n transitio
ns in the large deviations can be understood via a mapping to the\n classi
c Poland-Scheraga model for DNA denaturation [R. J. Harris and H.\n Touche
tte\, J. Phys. A: Math. Theor. 50\, 10LT01 (2017)]. This approach can\n
be extended to treat the case where the dynamics between resets depends on
\n the value of a parameter fixed at the last reset and\, in this context\
, I\n will briefly discuss the application to run-and-tumble models of bac
terial\n dynamics. Finally\, I will mention the recent development of a\n
"Thermodynamic Uncertainty Relation" which applies for such\n run-and-tumb
le–type processes [M. Shreshtha and R. J. Harris\, EPL\n (Europhysics Le
tters) 126\, 40007 (2019)].\n\nSpeaker:\n* Dr Rosemary Harris (Queen Mary
University of London)
LOCATION:Online
URL:https://www.ph.ed.ac.uk/events/2020/80085-current-fluctuations-in-rese
t-and-run-and-tumble-processes
END:VEVENT
BEGIN:VEVENT
CLASS:PUBLIC
UID:EVENT-80049@www.ph.ed.ac.uk
DTSTAMP:20210224T210121
CREATED:20200309T093743
LAST-MODIFIED:20200420T084826
STATUS:CONFIRMED
DTSTART;TZID=Europe/London:20200422T113000
DTEND;TZID=Europe/London:20200422T123000
SUMMARY:Wrinkle patterns in active viscoelastic thin sheets
DESCRIPTION:We show that a viscoelastic thin sheet driven out of equilibri
um by active structural remodelling develops a rich variety of shapes as
a result of a competition between viscous relaxation and activity. In the
regime where active processes are faster than viscoelastic relaxation\, w
rinkles that are formed due to remodelling are unable to relax to a confi
guration that minimises the elastic energy and the sheet is inherently ou
t of equilibrium. We argue that this non-equilibrium regime is of particu
lar interest in biology as it allows the system to access morphologies tha
t are unavailable if restricted to the adiabatic evolution between config
urations that minimise the elastic energy alone. Here\, we introduce acti
vity using the formalism of an evolving target metric and showcase the div
ersity of wrinkling morphologies arising from out of equilibrium dynamics
. \n\nSpeaker:\n* Dr Rastko Sknepnek (University of Dundee)
LOCATION:Online
URL:https://www.ph.ed.ac.uk/events/2020/80049-wrinkle-patterns-in-active-v
iscoelastic-thin-sheets
END:VEVENT
BEGIN:VEVENT
CLASS:PUBLIC
UID:EVENT-80099@www.ph.ed.ac.uk
DTSTAMP:20210224T210121
CREATED:20200426T102532
LAST-MODIFIED:20200426T102651
STATUS:CONFIRMED
DTSTART;TZID=Europe/London:20200429T113000
DTEND;TZID=Europe/London:20200429T123000
SUMMARY:Will a large stable system be complex?
DESCRIPTION:We consider a first-order dynamical system where the NxN pairw
ise interaction matrix is random and sparse\, i.e. it is the (weighted) ad
jacency matrix of an underlying random graph. We focus on the transient be
haviour in the vicinity of a stationary point. The squared norm of the pop
ulation vector — averaged over the random graph ensemble and uniform ini
tial conditions — may exhibit a large degree of universality at short ti
mes. For oriented graphs\, we can universally characterise the transient b
ehaviour solely in terms of the average connectivity c\, the variance σ2
of the bond disorder\, and simple spectral properties (e.g. presence and l
ocation of outliers). Our predictions are numerically tested on a wide var
iety of graph topologies and bond disorder with excellent agreement\, as w
ell as on simulated first-order dynamics on small empirical networks. On t
he technical side\, the results follow from the calculation of a Dunford-T
aylor integral over the two-point resolvent of random graphs\, which can b
e efficiently computed for large N using the celebrated ‘cavity method
’ — borrowed from the physics of disordered systems.\n\nJoint work wit
h Izaak Neri (King's College London) and Wojciech Tarnowski (Krakow). [htt
ps://arxiv.org/abs/1906.10634]\n\nSpeaker:\n* Dr Pierpaolo Vivo (Dept of M
athematics\, King's College London)
LOCATION:Online - see email.
URL:https://www.ph.ed.ac.uk/events/2020/80099-will-a-large-stable-system-b
e-complex
END:VEVENT
BEGIN:VEVENT
CLASS:PUBLIC
UID:EVENT-80221@www.ph.ed.ac.uk
DTSTAMP:20210224T210121
CREATED:20200507T181754
LAST-MODIFIED:20200511T094357
STATUS:CONFIRMED
DTSTART;TZID=Europe/London:20200513T113000
DTEND;TZID=Europe/London:20200513T123000
SUMMARY:Speed-dispersion-induced alignment: A one-dimensional model inspir
ed by swimming droplets experiments
DESCRIPTION:Richard will discuss the paper:\n\nSpeed-dispersion-induced al
ignment: A one-dimensional model inspired by swimming droplets experim
ents\n\nby Illien et al (2020) Physical Review E 101\, 040602(R)\n\nDetai
ls of talk:\n\nThis paper outlines some experiments of out-of-equilibrium
water droplets that are confined to a one-dimensional channel\, have an ex
cluded volume interaction and collide inelastically. A model of the observ
ed dynamics demonstrates that an interplay between activity and the inelas
tic collisions leads to macroscopic alignment when (i) the energy lost in
collisions is high and (ii) the rate at which particles return to their us
ual speed is low. It also suggests the transient appearance of condensates
at the earlier stages of the alignment process. This system is of interes
t as it combines aspects of persistent exclusion processes (aka run-and-tu
mble) and flocking models.\n\nSpeaker:\n* Professor Richard Blythe (School
of Physics & Astronomy\, University of Edinburgh)
LOCATION:Online - see email.
URL:https://www.ph.ed.ac.uk/events/2020/80221-speed-dispersion-induced-ali
gnment-a-one-dimensional-model-inspired-by-swimming-droplets-experiments
END:VEVENT
BEGIN:VEVENT
CLASS:PUBLIC
UID:EVENT-80222@www.ph.ed.ac.uk
DTSTAMP:20210224T210121
CREATED:20200507T181905
LAST-MODIFIED:20200518T101033
STATUS:CONFIRMED
DTSTART;TZID=Europe/London:20200520T113000
DTEND;TZID=Europe/London:20200520T123000
SUMMARY:Steady-state currents in active matter: origin and implications
DESCRIPTION:It is well known that under rather generic circumstances activ
e systems can generate currents due to\, say\, an external potential. In t
he talk\, I will discuss several implications of this fact on the physics
of different systems. Specifically\, I will focus on interactions between
objects immersed in an active fluid\, the effects of disorder on active pa
rticles\, and escape problems.\n\nSpeaker:\n* Professor Yariv Kafri (Techn
ion)
LOCATION:Online - see email.
URL:https://www.ph.ed.ac.uk/events/2020/80222-steady-state-currents-in-act
ive-matter-origin-and-implications
END:VEVENT
BEGIN:VEVENT
CLASS:PUBLIC
UID:EVENT-80215@www.ph.ed.ac.uk
DTSTAMP:20210224T210121
CREATED:20200502T175822
LAST-MODIFIED:20200519T093848
STATUS:CONFIRMED
DTSTART;TZID=Europe/London:20200527T113000
DTEND;TZID=Europe/London:20200527T123000
SUMMARY:On the largest eigenvalue of a random matrix: Tracy-Widom distribu
tion\, large deviations and third order phase transition.
DESCRIPTION:The statistical properties of the largest eigenvalue $\\lambda
_{\\max}$ of a random matrix are of interest in diverse fields such as in
the stability of large ecosystems\, in disordered systems and related st
ochastic growth processes\, in statistical data analysis and even in stri
ng theory. In this talk I will review the developments in the theory of t
he fluctuations of $\\lambda_{\\max}$ in the classical Gaussian ensembles
of Random Matrix Theory -- such as the Gaussian Orthogonal Ensemble. In
the limit of large matrix size $N$\, the probability density function (PD
F) $\\lambda_{\\max}$ consists of a central part described by the celebra
ted Tracy-Widom distribution flanked\, on both sides\, by two large devia
tions tails. While the central part characterizes the typical fluctuati
ons of $\\lambda_{\\max}$\, the large deviations tails are instead asso
ciated to extremely rare fluctuations. I will discuss in particular the t
hird-order phase transition which separates the left tail from the right t
ail\, a transition akin to the so-called Gross-Witten-Wadia phase trans
ition found in 2-d lattice quantum chromodynamics. If time permits\, I wi
ll discuss the occurrence of similar third-order transitions in various
physical problems\, such as the Sardar-Parisi-Zhang equation in $1+1$ di
mensions. \n\nSpeaker:\n* Dr Gregory Schehr (Université de Paris-Sud)
LOCATION:Online - see email.
URL:https://www.ph.ed.ac.uk/events/2020/80215-on-the-largest-eigenvalue-of
-a-random-matrix-tracy-widom-distribution-large-deviations-and-third
END:VEVENT
BEGIN:VEVENT
CLASS:PUBLIC
UID:EVENT-80223@www.ph.ed.ac.uk
DTSTAMP:20210224T210121
CREATED:20200507T182701
LAST-MODIFIED:20200527T093235
STATUS:CONFIRMED
DTSTART;TZID=Europe/London:20200603T113000
DTEND;TZID=Europe/London:20200603T123000
SUMMARY:Some exact results on continuous-time quantum walks
DESCRIPTION: Quantum analogs of classical random walks have been defined
in quantum information theory as a useful concept to implement algorit
hms. Due to interference effects\, statistical properties of quantum
walks can drastically differ from their classical counterparts\, leading
to much faster computations.\n \n In this talk\, we shall discuss
various statistical properties of continuous-time quantum walks on a
lattice\, such as: survival properties of quantum particles in the pr
esence of traps\, the growth of a quantum population in the presence
of a source\, and quantum return probabilities (Loschmidt echoes).\n\nS
peaker:\n* Kirone Mallick (CEA Saclay)
LOCATION:Online - see email.
URL:https://www.ph.ed.ac.uk/events/2020/80223-some-exact-results-on-contin
uous-time-quantum-walks
END:VEVENT
BEGIN:VEVENT
CLASS:PUBLIC
UID:EVENT-80250@www.ph.ed.ac.uk
DTSTAMP:20210224T210121
CREATED:20200526T134546
LAST-MODIFIED:20200526T134546
STATUS:CONFIRMED
DTSTART;TZID=Europe/London:20200610T113000
DTEND;TZID=Europe/London:20200610T123000
SUMMARY:Dynamical Large Deviations of Reflected Diffusions
DESCRIPTION:In this talk I discuss the calculation of the large deviation
functions characterizing the fluctuations of dynamical observables of Mark
ov diffusions with reflecting boundaries. In practice\, these large deviat
ion functions are often found via a spectral calculation. The proper bound
ary conditions for this spectral calculation in the presence of reflecting
boundaries is discussed\, and the implications for the driven process (wh
ich describes how fluctuations arise in the long-time limit) are explored.
As an illustration of our results\, I will discuss two particular applica
tions (reflected Ornstein-Uhlenbeck process and reflected Brownian motion
with drift). Finally\, I mention open problems and possible extensions of
this work. \n\nSpeaker:\n* Johan du Buisson (Stellenbosch University\, De
partment of Physics)
URL:https://www.ph.ed.ac.uk/events/2020/80250-dynamical-large-deviations-o
f-reflected-diffusions
END:VEVENT
BEGIN:VEVENT
CLASS:PUBLIC
UID:EVENT-80234@www.ph.ed.ac.uk
DTSTAMP:20210224T210121
CREATED:20200513T161021
LAST-MODIFIED:20200611T135128
STATUS:CONFIRMED
DTSTART;TZID=Europe/London:20200617T113000
DTEND;TZID=Europe/London:20200617T123000
SUMMARY:Bringing together two paradigms of non-equilibrium: Driven dynamic
s of aging systems
DESCRIPTION:Non-equilibrium behaviour can be broadly split into two catego
ries. The first is aging\, where a system can in principle reach an equi
librium state but its slow dynamics leads to extremely long transients dur
ing which the properties of the system depend on its age since preparation
. In the second category are driven systems\, whose dynamics breaks detail
ed balance leading to non-equilibrium steady states. An attractive way of
constructing descriptions of such driven systems is based on maximum entro
py arguments in trajectory space\, leading to so-called biased trajectory
ensembles.\n In this talk I will describe how these two non-equilibrium sc
enarios interact\, by studying the bias-driven dynamics of two simple mode
ls that are inspired by the physics of glasses and exhibit aging at low te
mperatures. The analysis allows one to detect dynamical phase transitions
that reveal unexpected qualitative differences in the robustness of aging
to additional driving.\n\nSpeaker:\n* Professor Peter Sollich (Universitä
t Göttingen\, Institut für Theoretische Physik)
LOCATION:Online - see email.
URL:https://www.ph.ed.ac.uk/events/2020/80234-bringing-together-two-paradi
gms-of-non-equilibrium-driven-dynamics-of-aging-systems
END:VEVENT
BEGIN:VEVENT
CLASS:PUBLIC
UID:EVENT-80231@www.ph.ed.ac.uk
DTSTAMP:20210224T210121
CREATED:20200512T181215
LAST-MODIFIED:20200618T100731
STATUS:CONFIRMED
DTSTART;TZID=Europe/London:20200624T113000
DTEND;TZID=Europe/London:20200624T123000
SUMMARY:Flagellar length control in biflagellate eukaryotes: time-of-fligh
t\, shared pool\, train traffic and cooperative phenomena
DESCRIPTION:Flagella of eukaryotic cells are transient long cylindrical pr
otrusions. Very recently we have developed a stochastic model for flagell
ar length control based on a time-of-flight (ToF) mechanism. The proteins
needed to form and maintain flagella are synthesized in the cell body an
d transported to the distal tips by Intra-flagellar transport (IFT) train
s. We represent the traffic of IFT trains as a totally asymmetric simple
exclusion process (TASEP). The ToF mechanism for each flagellum\, togeth
er with the TASEP-based description of the IFT trains\, combined with a
scenario of sharing of a common pool of flagellar structural proteins in
biflagellates\, can account for all key features of experimentally known
phenomena. These include ciliogenesis\, resorption\, deflagellation as w
ell as regeneration after selective amputation of one of the two flagella
. Moreover\, we make new predictions on the flagellar length fluctuations
and the role of the common pool.\n\nSpeaker:\n* Professor Debashish Chow
dhury FNA\, FASc\, FNASc (Department of Physics\, Indian Institute of Tech
nology\, Kanpur 208016\, India)
LOCATION:Online - see email.
URL:https://www.ph.ed.ac.uk/events/2020/80231-flagellar-length-control-in-
biflagellate-eukaryotes-time-of-flight-shared-pool-train-traffic-and
END:VEVENT
BEGIN:VEVENT
CLASS:PUBLIC
UID:EVENT-80252@www.ph.ed.ac.uk
DTSTAMP:20210224T210121
CREATED:20200526T135145
LAST-MODIFIED:20200526T135145
STATUS:CONFIRMED
DTSTART;TZID=Europe/London:20200701T113000
DTEND;TZID=Europe/London:20200701T123000
SUMMARY:Numerical computation and estimation of large deviations
DESCRIPTION:I will give in this talk a basic overview of numerical methods
developed recently for computing large deviation functions characterizing
the fluctuations of observables of Markov processes\, which are used in s
tatistical physics to model nonequilibrium processes. I will focus on two
methods - direct diagonalization and importance sampling - to explain how
the estimation of large deviations relates in general to optimal control t
heory\, and what differences or difficulties arise when treating reversibl
e vs non-reversible processes. I will end by discussing pros and cons of d
ifferent numerical methods\, as well as problems that remain in the field
of numerical large deviations.\n\nSpeaker:\n* Professor Hugo Touchette (St
ellenbosch University\, Department of Mathematical Sciences)
URL:https://www.ph.ed.ac.uk/events/2020/80252-numerical-computation-and-es
timation-of-large-deviations
END:VEVENT
BEGIN:VEVENT
CLASS:PUBLIC
UID:EVENT-80229@www.ph.ed.ac.uk
DTSTAMP:20210224T210121
CREATED:20200511T100859
LAST-MODIFIED:20200702T094222
STATUS:CONFIRMED
DTSTART;TZID=Europe/London:20200708T113000
DTEND;TZID=Europe/London:20200708T123000
SUMMARY:Absolute Negative Mobility: can it take place in thermal equilibri
um?
DESCRIPTION:Absolute Negative Mobility (ANM) is a phenomenon whereby curre
nt in a stationary system is in a direction opposite to the driving fi
eld. Naïve argument suggests that ANM cannot take place in systems in th
ermal equilibrium as this could lead to a violation of the second law of
thermodynamics. Thus numerous previous theoretical and experimental studie
s of ANM have dealt with the response to a driving field in nonequilibriu
m steady states. In this talk a simple lattice model of a driven trace
r is introduced and demonstrated to exhibit ANM in equilibrium\, with no
violation of the basic laws of thermodynamics. The limits of validity o
f the naïve argument are elucidated and the entropy production which acc
ompany the motion of the tracer is calculated.\n\nSpeaker:\n* David Mukame
l (Department of Physics of Complex Systems Weizmann Institute of Science
Israel)
LOCATION:Online - see email.
URL:https://www.ph.ed.ac.uk/events/2020/80229-absolute-negative-mobility-c
an-it-take-place-in-thermal-equilibrium
END:VEVENT
BEGIN:VEVENT
CLASS:PUBLIC
UID:EVENT-80900@www.ph.ed.ac.uk
DTSTAMP:20210224T210121
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:20210224T210121
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:20210224T210121
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:20210224T210121
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:20210224T210121
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:20210224T210121
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:20210224T210121
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:20210224T210121
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:20210224T210121
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:20210224T210121
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:20210224T210121
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:20210224T210121
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:20210224T210121
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:20210224T210121
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:20210224T210121
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:20210224T210121
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:20210224T210121
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:20210224T210121
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:20210224T210121
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:20210224T210121
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:20210224T210121
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-80911@www.ph.ed.ac.uk
DTSTAMP:20210224T210121
CREATED:20200913T105552
LAST-MODIFIED:20200913T110318
STATUS:CONFIRMED
DTSTART;TZID=Europe/London:20210317T113000
DTEND;TZID=Europe/London:20210317T123000
SUMMARY:TBD
DESCRIPTION:TBD\n\nSpeaker:\n* Professor Michael Cates (DAMTP\, Cambridge)
URL:https://www.ph.ed.ac.uk/events/2021/80911-tbd
END:VEVENT
BEGIN:VEVENT
CLASS:PUBLIC
UID:EVENT-81283@www.ph.ed.ac.uk
DTSTAMP:20210224T210121
CREATED:20210208T201842
LAST-MODIFIED:20210208T201842
STATUS:CONFIRMED
DTSTART;TZID=Europe/London:20210331T113000
DTEND;TZID=Europe/London:20210331T123000
SUMMARY:TBA
DESCRIPTION:TBA\n\nSpeaker:\n* Cesare Nardini ( CEA-Saclay\, France)
LOCATION:Online - see email
URL:https://www.ph.ed.ac.uk/events/2021/81283-tba
END:VEVENT
BEGIN:VEVENT
CLASS:PUBLIC
UID:EVENT-81296@www.ph.ed.ac.uk
DTSTAMP:20210224T210121
CREATED:20210214T164140
LAST-MODIFIED:20210214T164140
STATUS:CONFIRMED
DTSTART;TZID=Europe/London:20210407T113000
DTEND;TZID=Europe/London:20210407T123000
SUMMARY:TBA
DESCRIPTION:TBA\n\nSpeaker:\n* Anupam Kundu (International centre for theo
retical sciences\, Bangalore)
LOCATION:Online - see email
URL:https://www.ph.ed.ac.uk/events/2021/81296-tba
END:VEVENT
BEGIN:VEVENT
CLASS:PUBLIC
UID:EVENT-81328@www.ph.ed.ac.uk
DTSTAMP:20210224T210121
CREATED:20210224T164833
LAST-MODIFIED:20210224T164833
STATUS:CONFIRMED
DTSTART;TZID=Europe/London:20210414T113000
DTEND;TZID=Europe/London:20210414T123000
SUMMARY:TBA
DESCRIPTION:TBA\n\nSpeaker:\n* Prof Leonie Canet (University Grenoble Alpe
s)
LOCATION:Online - see email
URL:https://www.ph.ed.ac.uk/events/2021/81328-tba
END:VEVENT
BEGIN:VEVENT
CLASS:PUBLIC
UID:EVENT-81168@www.ph.ed.ac.uk
DTSTAMP:20210224T210121
CREATED:20201210T164758
LAST-MODIFIED:20210223T191814
STATUS:CONFIRMED
DTSTART;TZID=Europe/London:20210421T113000
DTEND;TZID=Europe/London:20210421T123000
SUMMARY:TBA
DESCRIPTION:TBA\n\nSpeaker:\n* Michael Assaf (The Racah Institute of Physi
cs)
LOCATION:Online - see email
URL:https://www.ph.ed.ac.uk/events/2021/81168-tba
END:VEVENT
BEGIN:VEVENT
CLASS:PUBLIC
UID:EVENT-81286@www.ph.ed.ac.uk
DTSTAMP:20210224T210121
CREATED:20210211T154516
LAST-MODIFIED:20210224T164735
STATUS:CONFIRMED
DTSTART;TZID=Europe/London:20210428T113000
DTEND;TZID=Europe/London:20210428T123000
SUMMARY:TBA
DESCRIPTION:TBA\n\nSpeaker:\n* Professor Alexander Morozov (School of Phys
ics & Astronomy\, University of Edinburgh)
LOCATION:Online - see email
URL:https://www.ph.ed.ac.uk/events/2021/81286-tba
END:VEVENT
END:VCALENDAR