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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
END:DAYLIGHT
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-78588@www.ph.ed.ac.uk
DTSTAMP:20200119T133038
CREATED:20190108T071512
LAST-MODIFIED:20190114T121615
STATUS:CONFIRMED
DTSTART;TZID=Europe/London:20190123T113000
DTEND;TZID=Europe/London:20190123T123000
SUMMARY:Wave solution of non-linear conservation laws II
DESCRIPTION:I will complete what's left from Part I\, then go through an e
xplicit solution of the shallow water waves equations with some set of ini
tial conditions. Time permitting\, I will also give a brief description of
a numerical scheme to deal with general initial conditions.\n\nSpeaker:\n
* Mr Francesco Cagnetta (School of Physics & Astronomy\, University of Edi
nburgh)
LOCATION:Room 4309\, JCMB
URL:https://www.ph.ed.ac.uk/events/2019/78588-wave-solution-of-non-linear-
conservation-laws-ii
END:VEVENT
BEGIN:VEVENT
CLASS:PUBLIC
UID:EVENT-78589@www.ph.ed.ac.uk
DTSTAMP:20200119T133038
CREATED:20190108T071547
LAST-MODIFIED:20190128T065533
STATUS:CONFIRMED
DTSTART;TZID=Europe/London:20190130T113000
DTEND;TZID=Europe/London:20190130T123000
SUMMARY:The Lieb-Yngvason theory of thermodynamics
DESCRIPTION:The structure of thermodynamics follows from the existence of
an extensive\, additive\, and concave entropy function. Yet despite the ce
ntrality of entropy in the theory\, it is often introduced in a roundabout
way via heat engines\, or by invoking notions from statistical mechanics.
Attempts during the during the 20thcentury to formulate a conceptually se
lf-contained and mathematically rigorous version of thermodynamics culmina
ted in the work of Lieb and Yngvason in 1999. They show that a certain phy
sically intuitive notion of ‘adiabatic accessibility’ is mathematicall
y equivalent to the existence of a unique entropy function with the desire
d properties. This modern understanding of thermodynamics is also relevant
to understanding why nonequilibrium physics cannot be similarly encapsula
ted by an entropy principle. I will introduce this theory to the audience.
\n\nSpeaker:\n* Mr Emil Mallmin (School of Physics & Astronomy\, Universit
y of Edinburgh)
LOCATION:Room 2511\, JCMB
URL:https://www.ph.ed.ac.uk/events/2019/78589-the-lieb-yngvason-theory-of-
thermodynamics
END:VEVENT
BEGIN:VEVENT
CLASS:PUBLIC
UID:EVENT-78590@www.ph.ed.ac.uk
DTSTAMP:20200119T133038
CREATED:20190108T071625
LAST-MODIFIED:20190204T121623
STATUS:CONFIRMED
DTSTART;TZID=Europe/London:20190206T113000
DTEND;TZID=Europe/London:20190206T123000
SUMMARY:The Blowtorch Theorem
DESCRIPTION:I will discuss the "Blowtorch theorem" (BT) based on the artic
le "Maes & Netocny\, Ann. Henri Poincaré 14 (2013)". In the framework of
Markov jump processes\, an equilibrium steady state is determined by the e
nergy/entropy part of the transition rates. A nonequilibrium steady state\
, on the other hand\, depends also on the kinetic part. The BT gives a con
dition suggestive of the Comparison Hypothesis (as discussed last week)\,
for when the effect of kinetics is in a sense strong. We will review Kirch
off’s graph-theoretical method of solving the master equation\, and use
it to derive the Blowtorch theorem.\n\nSpeaker:\n* Mr Emil Mallmin (School
of Physics & Astronomy\, University of Edinburgh)
LOCATION:Room 2511\, JCMB
URL:https://www.ph.ed.ac.uk/events/2019/78590-the-blowtorch-theorem
END:VEVENT
BEGIN:VEVENT
CLASS:PUBLIC
UID:EVENT-78591@www.ph.ed.ac.uk
DTSTAMP:20200119T133038
CREATED:20190108T071658
LAST-MODIFIED:20190211T115522
STATUS:CONFIRMED
DTSTART;TZID=Europe/London:20190213T113000
DTEND;TZID=Europe/London:20190213T123000
SUMMARY:The Kramers-Moyal expansion
DESCRIPTION:The Kramers-Moyal expansion is a very useful tool for obtainin
g equations for the evolution of stochastic variables given a master equat
ion formulism. In this talk\, I will derive the Kramers-Moyal expansion an
d discuss when the truncation of this expansion to a Fokker-Planck equatio
n is valid. I will then give a few examples of simple systems where the Kr
amers-Moyal approximation can be used.\n\nSpeaker:\n* Mr Eoin Ó Laighléi
s (School of Physics & Astronomy\, University of Edinburgh)
LOCATION:Room 2511\, JCMB
URL:https://www.ph.ed.ac.uk/events/2019/78591-the-kramers-moyal-expansion
END:VEVENT
BEGIN:VEVENT
CLASS:PUBLIC
UID:EVENT-78606@www.ph.ed.ac.uk
DTSTAMP:20200119T133038
CREATED:20190114T121927
LAST-MODIFIED:20190219T140749
STATUS:CONFIRMED
DTSTART;TZID=Europe/London:20190220T113000
DTEND;TZID=Europe/London:20190220T123000
SUMMARY:Continuum solution of a many-filament Brownian ratchet
DESCRIPTION:I will present a derivation of a two-filament Brownian ratchet
in continuous space\, that generalises to N filaments. Here\, two inhomog
eneous filaments grow and contract\, and interact with a drift-diffusing m
embrane by exclusion. This system approaches a steady state whereby the me
mbrane has a net drift over time induced by a `ratcheting' mechanism. By
taking the continuum limit of a more intuitive lattice-based system\, I de
rive and solve a diffusion equation and set of boundary conditions for thi
s system\, and calculate the steady state velocity of the system as a func
tion of the filament and membrane properties.\n This derivation in fact ge
neralises to an arbitrary number of filaments\, as well as when there are
additional restoring forces between filaments and membrane\, or between ne
ighbouring filaments. From this\, we can draw parallels between this syste
m and the dynamics of actin filament networks that move the leading edge o
f eukaryotic cells.\n\nSpeaker:\n* Anthony Wood (Formerly School of Physic
s & Astronomy\, University of Edinburgh)
LOCATION:Room 2511\, JCMB
URL:https://www.ph.ed.ac.uk/events/2019/78606-continuum-solution-of-a-many
-filament-brownian-ratchet
END:VEVENT
BEGIN:VEVENT
CLASS:PUBLIC
UID:EVENT-78656@www.ph.ed.ac.uk
DTSTAMP:20200119T133038
CREATED:20190208T064549
LAST-MODIFIED:20190208T064549
STATUS:CONFIRMED
DTSTART;TZID=Europe/London:20190313T113000
DTEND;TZID=Europe/London:20190313T123000
SUMMARY:Martin TBC
DESCRIPTION:Abstract TBC\n\nSpeaker:\n* Professor Martin Evans (School of
Physics & Astronomy\, University of Edinburgh)
LOCATION:Room 2511\, JCMB
URL:https://www.ph.ed.ac.uk/events/2019/78656-martin-tbc
END:VEVENT
BEGIN:VEVENT
CLASS:PUBLIC
UID:EVENT-78715@www.ph.ed.ac.uk
DTSTAMP:20200119T133038
CREATED:20190307T174553
LAST-MODIFIED:20190401T071901
STATUS:CONFIRMED
DTSTART;TZID=Europe/London:20190403T113000
DTEND;TZID=Europe/London:20190403T123000
SUMMARY:Creating a start-up business from your research - the story of Quo
rate Technology
DESCRIPTION:The SPC talk on Wednesday will have a different theme from mos
t of our talks. The topic will be the challenges of successfully commercia
lising academic research. Our speakers will be Nick Rankin\, CEO\, and Mik
e Lincoln\, CTO\, of Quorate Technology a company they co-founded in 2012
as a spin-out from the Centre for Speech Technology Research at The Univer
sity of Edinburgh. They have kindly agreed to talk about their experiences
and briefly about their speech recognition technology.\n\n\n\nThe aim is
to make this an interactive session so please bring any questions you have
about commercialisation of your research.
LOCATION:2511
URL:https://www.ph.ed.ac.uk/events/2019/78715-creating-a-start-up-business
-from-your-research-the-story-of-quorate-technology
END:VEVENT
BEGIN:VEVENT
CLASS:PUBLIC
UID:EVENT-78682@www.ph.ed.ac.uk
DTSTAMP:20200119T133038
CREATED:20190220T134453
LAST-MODIFIED:20190408T110232
STATUS:CONFIRMED
DTSTART;TZID=Europe/London:20190410T113000
DTEND;TZID=Europe/London:20190410T123000
SUMMARY:A Simple Introduction to Solvable Vertex Models and Integrable Qua
ntum Spin Chains
DESCRIPTION:I will give a simple description of statistical-mechanical ve
rtex models and then use the transfer matrix approach to relate them to q
uantum spin chains. I will show how a class of such models which are exac
tly solvable are related to solutions of the Yang-Baxter equation. I will
then attempt to give a flavour of the Algebraic Bethe Ansatz technique
for finding the eigenvectors and eigenvalues of the quantum Hamiltonian\
, and mention how this method is related to the existence of an underlyin
g quantum group symmetry.\n\nThe talk is aimed at beginners\; the intenti
on is that if you know what a partition function is you should be able to
follow it all.\n\nSpeaker:\n* Prof. Robert Weston (Heriot-Watt University)
LOCATION:Room 2511\, JCMB
URL:https://www.ph.ed.ac.uk/events/2019/78682-a-simple-introduction-to-sol
vable-vertex-models-and-integrable-quantum-spin-chains
END:VEVENT
BEGIN:VEVENT
CLASS:PUBLIC
UID:EVENT-78621@www.ph.ed.ac.uk
DTSTAMP:20200119T133038
CREATED:20190122T060234
LAST-MODIFIED:20190122T060234
STATUS:CONFIRMED
DTSTART;TZID=Europe/London:20190417T113000
DTEND;TZID=Europe/London:20190417T123000
SUMMARY:Fractons
DESCRIPTION:No\, not vibrational modes of fractal lattices\, the name has
been recycled for anyon-like excitations in 3d. \n\nThese have the peculi
ar feature of displaying reduced mobility - various sorts can only move in
planes\, lines or not at all. Just as anyons in the toric code can be tho
ught of as arising from gauging the global symmetry of the (standard\, nea
rest neighbour interaction) Ising model\, fractons can arise from gauging
subsystem symmetries. An old friend of mine\, the plaquette Ising model\,
provides an example.\n\nSpeaker:\n* Des Johnston (Heriot-Watt University)
LOCATION:Room 2511\, JCMB
URL:https://www.ph.ed.ac.uk/events/2019/78621-fractons
END:VEVENT
BEGIN:VEVENT
CLASS:PUBLIC
UID:EVENT-78676@www.ph.ed.ac.uk
DTSTAMP:20200119T133038
CREATED:20190219T140847
LAST-MODIFIED:20190219T140847
STATUS:CONFIRMED
DTSTART;TZID=Europe/London:20190424T110000
DTEND;TZID=Europe/London:20190424T123000
SUMMARY:Date reserved
DESCRIPTION:TBC
LOCATION:Room 2511\, JCMB
URL:https://www.ph.ed.ac.uk/events/2019/78676-date-reserved
END:VEVENT
BEGIN:VEVENT
CLASS:PUBLIC
UID:EVENT-78677@www.ph.ed.ac.uk
DTSTAMP:20200119T133038
CREATED:20190219T140922
LAST-MODIFIED:20190219T140922
STATUS:CONFIRMED
DTSTART;TZID=Europe/London:20190501T110000
DTEND;TZID=Europe/London:20190501T123000
SUMMARY:Date reserved
DESCRIPTION:TBC
LOCATION:Room 2511\, JCMB
URL:https://www.ph.ed.ac.uk/events/2019/78677-date-reserved
END:VEVENT
BEGIN:VEVENT
CLASS:PUBLIC
UID:EVENT-78846@www.ph.ed.ac.uk
DTSTAMP:20200119T133038
CREATED:20190506T173726
LAST-MODIFIED:20190506T173726
STATUS:CONFIRMED
DTSTART;TZID=Europe/London:20190508T113000
DTEND;TZID=Europe/London:20190508T123000
SUMMARY:A stochastic 3D polymer model of transcriptional dynamics in chrom
atin: variability\, bursting and omnigenic effects
DESCRIPTION:The regulation of the transcriptional programme in a cell is k
ey to its correct functioning\, and underlies diverse phenomena such as d
evelopment\, aging\, and diseases. Here we propose and study a biophysic
al stochastic and nonequilibrium model for transcriptional dynamics based
on the binding of diffusing multivalent transcription factors to chromat
in in 3D. The results show that the coupling between 3D chromatin structu
re and transcription naturally yields stochastic\, bursty transcription\,
and complex gene correlation networks in the absence of any biochemical
regulation. We will discuss a possible way to capture similar phenomeno
logy with a 1D model.\n\nSpeaker:\n* Professor Davide Marenduzzo (School o
f Physics & Astronomy\, University of Edinburgh)
LOCATION:Room 2511\, JCMB
URL:https://www.ph.ed.ac.uk/events/2019/78846-a-stochastic-3d-polymer-mode
l-of-transcriptional-dynamics-in-chromatin-variability-bursting-and
END:VEVENT
BEGIN:VEVENT
CLASS:PUBLIC
UID:EVENT-78678@www.ph.ed.ac.uk
DTSTAMP:20200119T133038
CREATED:20190219T140951
LAST-MODIFIED:20190219T140951
STATUS:CONFIRMED
DTSTART;TZID=Europe/London:20190515T110000
DTEND;TZID=Europe/London:20190515T123000
SUMMARY:Date reserved
DESCRIPTION:TBC
LOCATION:Room 2511\, JCMB
URL:https://www.ph.ed.ac.uk/events/2019/78678-date-reserved
END:VEVENT
BEGIN:VEVENT
CLASS:PUBLIC
UID:EVENT-79450@www.ph.ed.ac.uk
DTSTAMP:20200119T133038
CREATED:20190625T135812
LAST-MODIFIED:20190625T140000
STATUS:CONFIRMED
DTSTART;TZID=Europe/London:20190626T103000
DTEND;TZID=Europe/London:20190626T113000
SUMMARY:Phase-space geometry of reaction-diffusion dynamics
DESCRIPTION:Fridtjof Brauns will speak about Phase-space geometry of \n
reaction-diffusion dynamics. (Please note the earlier time of 10:30.)
\n The talk should be of particular interest to those working on \n non
-equilibrium statistical mechanics.\n\nSee https://arxiv.org/abs/1812.086
84\n Experimental studies of protein pattern formation (both in vivo and i
n \n vitro) have stimulated new interest in the dynamics of \n react
ion--diffusion systems. However\, a comprehensive theoretical \n unders
tanding of the dynamics of such highly nonlinear\, spatially \n extende
d systems is still missing. Here we show how a description in \n phase
space\, which has proven invaluable in shaping our intuition \n about t
he dynamics of nonlinear ordinary differential equations\, can \n be ge
neralized to mass-conserving reaction--diffusion (McRD) systems.\n\nSpeake
r:\n* Fridtjof Brauns
LOCATION:Room 2511\, JCMB
URL:https://www.ph.ed.ac.uk/events/2019/79450-phase-space-geometry-of-reac
tion-diffusion-dynamics
END:VEVENT
BEGIN:VEVENT
CLASS:PUBLIC
UID:EVENT-79524@www.ph.ed.ac.uk
DTSTAMP:20200119T133038
CREATED:20190726T093830
LAST-MODIFIED:20190726T094104
STATUS:CONFIRMED
DTSTART;TZID=Europe/London:20190925T113000
DTEND;TZID=Europe/London:20190925T123000
SUMMARY:Temperature Interfaces in the Katz-Lebowitz-Spohn Driven Lattice G
as
DESCRIPTION:Authors: Ruslan I. Mukhamadiarov\, Priyanka\, Uwe C. Tauber\n
Department of Physics and Center for Soft Matter and Biological Physics\,\
n Virginia Tech\, Blacksburg\, VA\n We explore the intriguing spatial patt
erns that emerge in a two-dimensional \n spatially inhomogeneous Katz-Leb
owitz-Spohn (KLS) driven lattice gas with \n attractive nearest-neighbor
interactions. The domain is split into two \n regions with hopping rates
governed by different temperatures T > Tc and \n Tc\, respectively\, wher
e Tc indicates the critical temperature for phase \n ordering\, and with
the temperature boundaries oriented perpendicular to the \n drive. In the
hotter region\, the system behaves like the (totally) asymmetric\n exclus
ion processes (TASEP)\, and experiences particle blockage in front of \n
the interface to the critical region.\n To explain this particle density
\n accumulation near the interface\, we have measured the steady-state cur
rent in\n the KLS model at T > Tc and found it to decay as 1/T. In analogy
with TASEP \n systems containing "slow" bonds\, transport in the high-te
mperature subsystem \n is impeded by the lower current in the cooler regi
on\, which tends to set the \n global stationary particle current value.
This blockage is induced by the \n extended particle clusters\, growing l
ogarithmically with system size\, in the \n critical region. We observe t
he density profiles in both high-and low-\n temperature subsystems to be s
imilar to the well-characterized coexistence \n and maximal-current phase
s in (T)ASEP models with open boundary conditions\, \n which are respecti
vely governed by hyperbolic and trigonometric tangent \n functions. Yet i
f the lower temperature is set to Tc\, we detect marked \n fluctuation co
rrections to the mean-field density profiles\, e.g.\, the \n correspondin
g critical KLS power law density decay near the interfaces into \n the co
oler region. If the temperature interface is aligened parallel to the\n dr
ive\, we observe the cooler region to act as an absorbing sink for particl
e \n transport\, with blockages emerging at the subsystem boundaries.\n R
ef.: R.I. Mukhamadiarov\, Priyanka\, and U.C.T.\, arXiv:1907.08576\n Resea
rch was sponsored by the Army Research Office (ARO) and was accomplished\n
under Grant Number W911NF-17-1-0156.\n\nSpeaker:\n* Professor Uwe Tauber
(Virginia Tech)
LOCATION:Room 2511\, JCMB
URL:https://www.ph.ed.ac.uk/events/2019/79524-temperature-interfaces-in-th
e-katz-lebowitz-spohn-driven-lattice-gas
END:VEVENT
BEGIN:VEVENT
CLASS:PUBLIC
UID:EVENT-79688@www.ph.ed.ac.uk
DTSTAMP:20200119T133038
CREATED:20191007T084430
LAST-MODIFIED:20191007T084430
STATUS:CONFIRMED
DTSTART;TZID=Europe/London:20191009T113000
DTEND;TZID=Europe/London:20191009T123000
SUMMARY:RSB40 Conference update
DESCRIPTION:I will give an update on the conference "40 years of Replica S
ymmetry \n Breaking: A conference about systems with many states". I will
not \n discuss any of the technical details of replicas\, but will focus
on \n the interesting results obtained in areas like\n\nDeep neural netw
orks\n Statistical mechanics of protein evolution\n The glass transition\n
\n I will mention if the time the ongoing question of whether replica \n
symmetry breaking occurs in 3 dimensions.\n Slides and videos from the con
ference are available athttps://sites.google.com/view/rsb40/home\n\nSpeake
r:\n* Dr Peter Mottishaw (School of Physics & Astronomy\, University of Ed
inburgh)
LOCATION:Room 2511\, JCMB
URL:https://www.ph.ed.ac.uk/events/2019/79688-rsb40-conference-update
END:VEVENT
BEGIN:VEVENT
CLASS:PUBLIC
UID:EVENT-79675@www.ph.ed.ac.uk
DTSTAMP:20200119T133038
CREATED:20191002T163040
LAST-MODIFIED:20191002T163040
STATUS:CONFIRMED
DTSTART;TZID=Europe/London:20191016T113000
DTEND;TZID=Europe/London:20191016T123000
SUMMARY:Dynamical fluctuation theory in a nutshell
DESCRIPTION:A dynamical fluctuation is an atypical value of a time-integra
ted observable such as entropy production\, particle current\, or number o
f state transitions in a stochastic system. A comprehensive theory exists
for how to characterize the likelihood of a dynamical fluctuation\, and to
determine the ensemble of system trajectories which realize it\, given th
at the observation times involved are large. In this talk I will explain t
he basic elements of this theory in the context of Markov jump processes.
While somewhat technical\, most of the developments can be made physically
intuitive by exploiting the clear analogy to ensemble theory in equilibri
um physics\, with distributions over microstates generalized to distributi
on of dynamical trajectories\, and the large N-limit replaced by the large
t-limit. In the following session we apply these tools to an analytically
solvable model. \n\nSpeaker:\n* Mr Emil Mallmin (School of Physics & Ast
ronomy\, University of Edinburgh)
LOCATION:Room 2511\, JCMB
URL:https://www.ph.ed.ac.uk/events/2019/79675-dynamical-fluctuation-theory
-in-a-nutshell
END:VEVENT
BEGIN:VEVENT
CLASS:PUBLIC
UID:EVENT-79676@www.ph.ed.ac.uk
DTSTAMP:20200119T133038
CREATED:20191002T170513
LAST-MODIFIED:20191021T144533
STATUS:CONFIRMED
DTSTART;TZID=Europe/London:20191023T113000
DTEND;TZID=Europe/London:20191023T123000
SUMMARY:Dynamical fluctuations: a solved example
DESCRIPTION:In this talk I will apply the tools of dynamical large deviati
on theory introduced in the previous week's talk to a 1D asymmetric random
walk conditioned on spending a finite fraction of time at the origin. Thi
s problem was first studied by Nyawo & Touchette (PRE 98\, 052103 (2018))
in the continuum where they revealed a dynamical phase transition. At a c
ritical time-fraction\, there is a transition from trajectories localized
around the origin to trajectories which escape after some fraction of time
. The lattice version is solvable in closed form and is one of several mod
els examined in a recent publication of mine (J. Phys. A. 52 425002 (2019)
). \n\nSpeaker:\n* Mr Emil Mallmin (School of Physics & Astronomy\, Unive
rsity of Edinburgh)
LOCATION:Room 2511\, JCMB
URL:https://www.ph.ed.ac.uk/events/2019/79676-dynamical-fluctuations-a-sol
ved-example
END:VEVENT
BEGIN:VEVENT
CLASS:PUBLIC
UID:EVENT-79756@www.ph.ed.ac.uk
DTSTAMP:20200119T133038
CREATED:20191103T214145
LAST-MODIFIED:20191103T214222
STATUS:CONFIRMED
DTSTART;TZID=Europe/London:20191106T113000
DTEND;TZID=Europe/London:20191106T123000
SUMMARY:The Hopfield model of neural networks
DESCRIPTION:I will use the Hopfield model as a common thread to review som
e aspects of the statistical mechanics of neural networks. Starting from t
he definition of the model and connection with spin glasses\, I will discu
ss it's representation as a restricted Boltzmann machine and how\, within
the latter representation\, one can witness the emergence of the layered s
tructure typical of deep learning methods.\n The talk will serve as a pres
entation of the reading group---another weekly meeting focused on an aspec
t of theoretical statistical mechanics.\n\nSpeaker:\n* Mr Francesco Cagnet
ta (School of Physics & Astronomy\, University of Edinburgh)
LOCATION:Room 2511\, JCMB
URL:https://www.ph.ed.ac.uk/events/2019/79756-the-hopfield-model-of-neural
-networks
END:VEVENT
BEGIN:VEVENT
CLASS:PUBLIC
UID:EVENT-79673@www.ph.ed.ac.uk
DTSTAMP:20200119T133038
CREATED:20191002T152605
LAST-MODIFIED:20191111T103632
STATUS:CONFIRMED
DTSTART;TZID=Europe/London:20191113T113000
DTEND;TZID=Europe/London:20191113T123000
SUMMARY:Conference talks on turbulence and microswimmer collective behavio
ur
DESCRIPTION:Viktor Skultety and James Hitchen will give dry-runs of their
upcoming conference talks.\n\nJames' talk (~10 min):\n\nThe mechanism of l
ong turbulent lifetimes in a low-dimensional model of plane Couette flow\n
\nRecently\, our understanding of the transition to turbulence has signifi
cantly changed due to the discovery of exact solutions of the Navier-Stoke
s equations and the introduction of the self-sustaining process in paralle
l shear flows. This theory has been very successful in describing the main
features of weakly turbulent states\, including the metastable nature of
turbulence close to the transition and the super-exponential dependence of
its lifetime on the Reynolds number. The main strength of this approach i
s that it allows for a semi-analytical description of the turbulent dynami
cs in the form of a rather low-dimensional model. Here we systematically d
evelop a novel low-dimensional model that allows us to investigate the ori
gin of the very long turbulent life-times close to the transition. We find
that there exists a particular periodic orbit that acts as a porous refle
cting barrier between the laminar and turbulent states\, and that serves t
o greatly increase the time before relaminarisation.\n\nViktor's talk (~30
min):\n\nThe role of correlations in the collective behaviour of microswi
mmer suspensions\n\nThe main distinction of 'active matter' from its passi
ve counterpart is the ability to extract energy from the environment (cons
ume food) and convert it into directed motion. One of the most striking co
nsequences of this distinction is the appearance of collective motion in s
elf-propelled particles suspended in a fluid observed in recent experiment
s and simulations: at low densities particles move around in an uncorrelat
ed fashion\, while at higher densities they organise into jets and vortice
s comprising many individual swimmers. Although this problem received sign
ificant attention in recent years\, the precise origin of the transition i
s poorly understood. Here we present a novel kinetic theory that captures
correlations below the transition\, and is non-perturbative in the swimmer
density. We show that correlations cannot be neglected at any density.\n\
nSpeakers:\n* Mr Viktor Skultety (School of Physics & Astronomy\, Universi
ty of Edinburgh)\n* Mr James Hitchen (School of Physics & Astronomy\, Univ
ersity of Edinburgh)
LOCATION:Room 2511\, JCMB
URL:https://www.ph.ed.ac.uk/events/2019/79673-conference-talks-on-turbulen
ce-and-microswimmer-collective-behaviour
END:VEVENT
BEGIN:VEVENT
CLASS:PUBLIC
UID:EVENT-79817@www.ph.ed.ac.uk
DTSTAMP:20200119T133038
CREATED:20191119T153324
LAST-MODIFIED:20191119T153324
STATUS:CONFIRMED
DTSTART;TZID=Europe/London:20191120T113000
DTEND;TZID=Europe/London:20191120T123000
SUMMARY:Breaking replica symmetry at two different temperatures
DESCRIPTION:I will provide a basic introduction to the idea an overlap dis
tribution to describe phase transitions in disordered systems and for a si
mple problem show how this can be calculated using Parisi's replica symmet
ry breaking scheme. I will then summarise our current research on how thi
s can be extended to the overlap between 2 different temperatures. This re
search is in collaboration with Bernard Derrida.\n\nThe agenda.\n\n\n Intr
oduction to overlap distribution to describe phase transitions - ferromagn
et vs spin glass.\n \n \n Why we would like to know the overlap distributi
on between two different temperatures - chaos or not?\n \n \n Random energ
y model - the simplest non-trivial model.\n \n \n Overlap distribution in
the random energy model and 1 step replica symmetry breaking at a single t
emperature.\n \n \n Generalisation of the replica symmetry breaking scheme
to 2 temperatures.\n \n\n\nThe basic concepts of overlap distributions an
d replicas are discussed in Mézard\, M.\, Parisi\, G. and Virasoro\, M.\,
1987. Spin glass theory and beyond: An Introduction to the Replica Metho
d and Its Applications\n\nSpeaker:\n* Dr Peter Mottishaw (School of Physic
s & Astronomy\, University of Edinburgh)
LOCATION:Room 2511\, JCMB
URL:https://www.ph.ed.ac.uk/events/2019/79817-breaking-replica-symmetry-at
-two-different-temperatures
END:VEVENT
BEGIN:VEVENT
CLASS:PUBLIC
UID:EVENT-79795@www.ph.ed.ac.uk
DTSTAMP:20200119T133038
CREATED:20191111T124351
LAST-MODIFIED:20191127T101246
STATUS:CONFIRMED
DTSTART;TZID=Europe/London:20191127T113000
DTEND;TZID=Europe/London:20191127T123000
SUMMARY:Extreme value distributions: the “max-stable distribution” app
roach
DESCRIPTION:The maximum of some large set of independent\, identically-dis
tributed random variables is known to approach one of three distributions
(Fréchet\, Gumbel or Weibull). In this talk\, I will show that these are\
, in fact\, special cases of a common distribution\, a fact that can be es
tablished from a self-similarity property known in the trade as “max sta
bility”. Time permitting\, I will also write down a recipe for determini
ng the large-N limiting forms\, since this is likely to be most useful in
applications.\n\nSpeaker:\n* Professor Richard Blythe (School of Physics &
Astronomy\, University of Edinburgh)
LOCATION:Room 2511\, JCMB
URL:https://www.ph.ed.ac.uk/events/2019/79795-extreme-value-distributions-
the-max-stable-distribution-approach
END:VEVENT
BEGIN:VEVENT
CLASS:PUBLIC
UID:EVENT-79870@www.ph.ed.ac.uk
DTSTAMP:20200119T133038
CREATED:20191202T214514
LAST-MODIFIED:20191202T214514
STATUS:CONFIRMED
DTSTART;TZID=Europe/London:20191204T113000
DTEND;TZID=Europe/London:20191204T123000
SUMMARY:Continuous-time quantum walks
DESCRIPTION:Given a graph\, classical random walks evolve a probability di
stribution over its vertices. Quantum walks do the same but for wave funct
ions\, which are described by giving the wave's amplitude at each vertex.
A photon traversing an array of crystals is a physical example of a quantu
m walk. Here\, it's not just a particle walking a graph\, but a wave propa
gating through it and interfering with itself. Interference changes the be
haviour of the walk in surprising ways and it has been shown to provide po
werful computational advantages.\n\nIn this talk I'll introduce the topic
of continuous-time quantum walks. We will focus on studying the scattering
of wave packets on open graphs. The final goal is to explain Andrew M. Ch
ild's paper "Universal computation by quantum walk" (2009)\, which provide
s a method to execute any quantum computation (i.e. simulate any quantum e
volution) using quantum walks. If there's time left\, I will briefly discu
ss some of the algorithms that have been proposed using quantum walks.\n\n
Speaker:\n* Pablo Andres-Martinez (School of Informatics\, University of E
dinburgh)
LOCATION:Room 2511\, JCMB
URL:https://www.ph.ed.ac.uk/events/2019/79870-continuous-time-quantum-walk
s
END:VEVENT
BEGIN:VEVENT
CLASS:PUBLIC
UID:EVENT-79674@www.ph.ed.ac.uk
DTSTAMP:20200119T133038
CREATED:20191002T152858
LAST-MODIFIED:20191209T151111
STATUS:CONFIRMED
DTSTART;TZID=Europe/London:20191211T113000
DTEND;TZID=Europe/London:20191211T123000
SUMMARY:First-passage times of many persistent random walkers in higher di
mensions
DESCRIPTION:The field of active matter studies particles\, or collections
thereof\, which consume energy to perform motion. This defining property's
main consequence is the breaking of detailed balance: active systems are
inherently out of equilibrium\, and as such cannot be described by the Bol
tzmann distribution. With a general framework of non-equilibrium statistic
al mechanics lacking\, active-matter models serve as an effective means by
which we can develop our intuition for the former.\n\nOriginally inspired
by Escherichia coli bacteria\, one such set of models which have been hea
vily studied are run-and-tumble models. While much analytical work has bee
n conducted at a field-theoretic level\, almost all microscopic\, interact
ing run-and-tumble models are limited in particle number and are restricte
d to one dimension. Here\, we will first lift the latter restriction by pr
esenting an approximate solution to a two-particle first-passage problem i
n two dimensions. We will then extend this approach by generalising to N d
ilute particles in d dimensions\, and present evidence for clustering beha
viour even at very low densities.\n\nSpeaker:\n* Mr Matthew Metson (School
of Physics & Astronomy\, University of Edinburgh)
LOCATION:Room 2511\, JCMB
URL:https://www.ph.ed.ac.uk/events/2019/79674-first-passage-times-of-many-
persistent-random-walkers-in-higher-dimensions
END:VEVENT
END:VCALENDAR