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SUMMARY:Machine learning methods in estimates of heart rate variability
DTSTART;VALUE=DATE-TIME:20190920T150000Z
DTEND;VALUE=DATE-TIME:20190920T153000Z
DTSTAMP;VALUE=DATE-TIME:20201031T224050Z
UID:indico-contribution-9-329@zakopane.if.uj.edu.pl
DESCRIPTION:Speakers: Danuta Makowiec (Institute of Theoretical Physics an
d Astrophysics\, University of Gdansk)\nEnormous progress in machine learn
ing achievements\, going together with their excellent implementations on
user-friendly platforms\, have pushed many of us towards this\nmethodology
. Can we get better explanations for studied data? Can we get the explanat
ion easier? In the following we deal with data formed from recordings on h
ealthy people with different age and sex. The problem is how the age and/o
r sex influence the normal rhythm of a healthy heart.\n\nThe healthy human
heart remains under the permanent influence of both branches of the auton
omic neural system (ANS): the parasympathetic (considered to slow down hea
rt rate) and the sympathetic (considered to speed up heart rate). Many mea
sures estimating heart rate variability (HRV) have been proposed in order
to quantify the regulatory function of the ANS. Intensive studies on heal
thy population have found a correlation between an increase in age and a d
ecrease in many HRV indices. Therefore higher values of HRV have been attr
ibuted to better organization of feedback reflexes driving an organism's r
esponse to actual body needs. However\, there are observations suggesting
that abnormal levels of some indices should be related to erratic rhythms\
, i.e.\, rhythms resulting from remodeling of the cardiac tissue due to di
sease or aging. We hypothesize that increase of measures of dynamical pat
terns in elderly indicates at unhealthy autonomic activity\, or possible e
rratic rhythm associated with degradation of cardiac tissue\, or both. Suc
h erratic rhythms might be the first stage of developing silently arrhythm
ogenesis.\n\nThe task of separating different cardiac patient groups on th
e basis of HRV parameters is an urgent problem. If there are differences\,
it might be possible to find noninvasive marker for specific cardiac dise
ases. Answering to these questions demands wide knowledge about the way in
which information hidden in heart rate variability displays the actual st
ate of the heart regulatory system.\n\nhttps://zakopane.if.uj.edu.pl/event
/9/contributions/329/
LOCATION:Kraków
URL:https://zakopane.if.uj.edu.pl/event/9/contributions/329/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Problems in creating adequate stochastic model of memristors
DTSTART;VALUE=DATE-TIME:20190920T143000Z
DTEND;VALUE=DATE-TIME:20190920T150000Z
DTSTAMP;VALUE=DATE-TIME:20201031T224050Z
UID:indico-contribution-9-324@zakopane.if.uj.edu.pl
DESCRIPTION:Speakers: Alexander Dubkov (Lobachevsky State University)\nCur
rently\, the investigations of resistive switching have attracted much att
ention. Electronic devices\, the functioning of which is based on the resi
stive switching\, are called memristors. The memristor as a new fundamenta
l element of the electrical circuit that dissipates energy and has memory
was theoretically predicted by Chua in 1971\, but found its hardware imple
mentation only in 2008. It represents a thin (from several nanometers to s
everal tens nanometers in thickness) dielectric film sandwiched between tw
o conductive electrodes. The switching of a memristor from the low resista
nce state (LRS) to the high resistance state (HRS) is achieved by the rapt
ure of the filament by a voltage pulse (so-called RESET process). The fila
ment can be restored by a voltage pulse of the opposite polarity that resu
lts in the switching from the HRS back to LRS (so-called SET process). As
a result\, its current-voltage characteristic is nonlinear and takes the f
orm of hysteresis. At present\, memristors have found application in diver
se areas of science and technology ranging from information processing to
biologically inspired systems. In particular\, they are considered to be p
romising for application in the next generation non-volatile computer memo
ry (Resistive Random Access Memory\, ReRAM)\, in the neuromorphic computer
systems\, etc.\nAll previous theoretical and experimental studies have ne
glected the important effect of noise on the memory properties of these el
ements. As a result\, an adequate stochastic model of memristor\, taking i
nto account many different factors as well as internal and external noises
\, is still far from being constructed. Difficulties in creating an adequa
te model associated with complex physico-chemical reactions occurring insi
de the film under the action of an applied electric field\, the structure
of the conducting filament\, setting the right conditions at the boundarie
s with contacts\, various memristor materials\, etc. It has already become
clear that to create a real model of the device\, the ideal memristor mod
els proposed by Chua are not enough and it is necessary to consider the sy
stem as multistable in terms of statistical physics approach.\nIn this rep
ort after a brief overview of previous achievements in this area the new r
esults both theoretical and experimental studies of memristors performed i
n the “Laboratory of stochastic multistable systems” of National Resea
rch Lobachevsky State University of Nizhni Novgorod would be presented. Am
ong them\, experimental investigations of the resistive switching in a mem
ristor based on a thin film ZrO2(Y)/Ta2O5 stack under a random noise volta
ge in the form of white Gaussian noise signal with certain parameters\, me
asurements of the activation energies of oxygen ion diffusion in yttria st
abilized zirconia by flicker-noise spectroscopy\, probabilistic analysis o
f the voltage-controlled and the current-controlled ideal memristor under
the action of the external voltage in the form of Gaussian noise\, non-sta
tionary distributions and relaxation times in a stochastic model of memris
tor.\n\nhttps://zakopane.if.uj.edu.pl/event/9/contributions/324/
LOCATION:Kraków
URL:https://zakopane.if.uj.edu.pl/event/9/contributions/324/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Classification of diffusion modes in single particle tracking data
: feature based vs. deep learning approach
DTSTART;VALUE=DATE-TIME:20190920T153000Z
DTEND;VALUE=DATE-TIME:20190920T155000Z
DTSTAMP;VALUE=DATE-TIME:20201031T224050Z
UID:indico-contribution-9-285@zakopane.if.uj.edu.pl
DESCRIPTION:Speakers: Janusz Janusz Szwabiński (Wrocław University of Sc
ience and Technology)\nSingle-particle trajectories measured in microscopy
experiments contain important information about dynamic processes undergo
ing in a range of materials including living cells and tissues. However\,
extracting that information is not a trivial task due to the stochastic na
ture of particles’ movement and the sampling noise. It usually starts wi
th the detection of a corresponding motion type of a molecule\, because th
is information may already provide insight into mechanical properties of t
he molecule’s surrounding. \n\nThe most common analysis method uses mean
square displacement (MSD) curves. Within this approach\, one fits the the
oretical curves for various physical models to the data and then selects t
he best fit with statistical analysis. However\, in many cases\, the actua
l trajectories are too short for extracting meaningful information from th
e time-averaged MSDs. Moreover\, the finite localization precision adds a
term to the MSD\, which can limit the interpretation of the data.\n\nClass
ification of trajectories with machine learning (ML) algorithms is one of
the possible approaches to overcome the problems of the MSD method. It is
rooted in computer science and statistics. And it is very appealing becaus
e it would enable automated analysis of many hundreds or even thousands of
trajectories with a reduced amount of manual intervention and initial dat
a curation.\n\nSeveral attempts to analyze SPT trajectories with the tradi
tional ML methods have been already carried out. However\, the methods tha
t have been used for that purpose (e.g. Bayesian approach\, random forest
and a simple back-propagation neural network) belong to the class of so-c
alled feature-based methods. Each trajectory within this approach is descr
ibed by a set of human-engineered features and only those features are pro
vided as input to a classifier model. Thus\, similarly to the MSD based me
thods\, they require the preprocessing of raw data and their interpretabil
ity may be limited for short and noisy trajectories.\n\nIn the talk\, we w
ill present a novel classification method based on convolutional neural ne
tworks (CNN). CNNs is one of the most popular deep learning algorithms\, w
hich excels in image classification. Using them is very appealing because
they operate on raw data. They do not require any feature selection and ex
traction carried out by a human expert. Instead\, they use a cascade of mu
ltiple layers of nonlinear processing units for feature identification\, e
xtraction and transformation in order to learn multiple levels of data rep
resentations. The performance of the CNN classifier trained on artificial
trajectories will be compared with two popular feature based methods (rand
om forest and gradient boosting).\n\nReferences:\n1. Patrycja Kowalek\, Ha
nna Loch-Olszewska\, **Janusz Szwabiński**\, *Classification of diffusion
modes in single particle tracking data: feature based vs. deep learning a
pproach*\, arXiv:1902.07942\, submitted to Phys. Rev. E\n\nhttps://zakopan
e.if.uj.edu.pl/event/9/contributions/285/
LOCATION:Kraków
URL:https://zakopane.if.uj.edu.pl/event/9/contributions/285/
END:VEVENT
BEGIN:VEVENT
SUMMARY:$q$-Neighbor Majority-Vote Model on Complex Networks
DTSTART;VALUE=DATE-TIME:20190920T104000Z
DTEND;VALUE=DATE-TIME:20190920T110000Z
DTSTAMP;VALUE=DATE-TIME:20201031T224050Z
UID:indico-contribution-9-333@zakopane.if.uj.edu.pl
DESCRIPTION:Speakers: Andrzej Krawiecki (Faculty of Physics\, Warsaw Unive
rsity of Technology)\nA $q$-neighbor majority-vote model for the opinion f
ormation is introduced in which agents\nrepresented by two-state spins upd
ate their opinions on the basis of the opinions of \nrandomly chosen subse
ts of $q$ their neighbors ($q$-lobbies). The agents with probability \n$(1
-2p)$\, $0\\le p\\le1/2$\, obey the majority-vote \nrule in which the prob
ability of the opinion flip depends only on the sign of the resultant\nopi
nion of the $q$-lobby\, and with probability $2p$ act independently and ch
ange opinion or\nremain in the actual state with equal probabilities. Thus
\, the parameter $p$ controls the\ndegree of stochasticity in the model. I
n the model under study the\nagents are located in the nodes of complex ne
tworks\, e.g.\, Erd\\"os-R\\'enyi graphs or \nscale-free networks\, and th
e neighborhood of each agent consists of all agents \nconnected with him/h
er by edges\, out of which the $q$-lobby is chosen randomly at each \nstep
of the Monte Carlo simulation. This model is related to a recently introd
uced \n$q$-neighbor Ising model [A.\\ J\\c{e}drzejewski et al.\, Phys.\\ R
ev.\\ E 92\, 052105 (2015)\;\nA.\\ Chmiel et al.\, Int.\\ J.\\ Modern Phys
.\\ C 29\, 1850041 (2018)]\, with agents obeying \nMetropolis opinion upda
te rule\, in which\, in particular\, first-order ferromagnetic transition
was \nreported\, with the width of the hysteresis loop oscillating with $q
$. In contrast\, in the \n$q$-neighbor majority vote model only second-ord
er ferromagnetic transition is observed. \nTheory for this transition is p
resented both in the mean-field approximation\, valid for\nlarge mean degr
ees of nodes and large $q$\, and in a more elaborate pair approximation. I
n the\nlatter case the predicted location of the critical point $p_{c}$ ag
rees quantitatively with that\nobtained from Monte Carlo simulations for v
arious complex networks with broad range of \nmean degrees of nodes and si
zes of the $q$-lobby. Finite size scaling analysis shows that\nin the vici
nity of the critical point the magnetization shows scalin typical for the\
nmean-field Ising model\, with the critical exponent $\\beta = 1/2$\, but
other critical\nexponents depend on the topology of the underlying complex
network.\n\nhttps://zakopane.if.uj.edu.pl/event/9/contributions/333/
LOCATION:Kraków
URL:https://zakopane.if.uj.edu.pl/event/9/contributions/333/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Dynamical mean field theory of neural networks with power-law diso
rder
DTSTART;VALUE=DATE-TIME:20190920T102000Z
DTEND;VALUE=DATE-TIME:20190920T104000Z
DTSTAMP;VALUE=DATE-TIME:20201031T224050Z
UID:indico-contribution-9-298@zakopane.if.uj.edu.pl
DESCRIPTION:Speakers: Lukasz Kusmierz (RIKEN Center for Brain Science)\nTr
ansitions to chaos have been previously extensively studied in different s
etups of randomly connected networks. The prevailing assumption is that\,
due to the central limit theorem\, synaptic input can be modeled as a Gaus
sian random variable. In this scenario\, a continuous transition has been
found in rate models with smooth activation functions. However\, these mod
els do not take into account that neurons feature thresholds that cut off
small inputs. With such thresholds\, the transition to chaos in Gaussian n
etworks becomes discontinuous\, making it impossible for the network to st
ay close to the edge of chaos and to reproduce biologically relevant low a
ctivity states.\n\nHere we introduce a model with biologically motivated\,
heavy-tailed distribution of synaptic weights and analytically show that
it exhibits a continuous transition to chaos. Notably\, in this model the
edge of chaos is associated with well-known avalanches. We validate our pr
edictions in simulations of networks of binary as well as leaky integrate
and fire neurons. Our results uncover an important functional role of non-
Gaussian distributions of synaptic efficacy and suggest that their heavy t
ails may form a weak sparsity prior that can be useful in biological and a
rtificial adaptive systems.\n\nhttps://zakopane.if.uj.edu.pl/event/9/contr
ibutions/298/
LOCATION:Kraków
URL:https://zakopane.if.uj.edu.pl/event/9/contributions/298/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Entropy Production in Open Systems: The Predominant Role of Intra-
Environment Correlations
DTSTART;VALUE=DATE-TIME:20190920T100000Z
DTEND;VALUE=DATE-TIME:20190920T102000Z
DTSTAMP;VALUE=DATE-TIME:20201031T224050Z
UID:indico-contribution-9-308@zakopane.if.uj.edu.pl
DESCRIPTION:Speakers: Krzysztof Ptaszyński (Institute of Molecular Physic
s\, Polish Academy of Sciences)\nWe show that the entropy production in sm
all open systems coupled to environments made of extended baths is predomi
nantly caused by the displacement of the environment from equilibrium rath
er than\, as often assumed\, the mutual information between the system and
the environment. The latter contribution is strongly bounded from above b
y the Araki-Lieb inequality\, and therefore is not time-extensive\, in con
trast to the entropy production itself. Furthermore\, we show that in the
thermodynamic limit the entropy production is associated mainly with gener
ation of the mutual information between initially uncorrelated environment
al degrees of freedom. We confirm our results with exact numerical calcula
tions of the system-environment dynamics.\n\nhttps://zakopane.if.uj.edu.pl
/event/9/contributions/308/
LOCATION:Kraków
URL:https://zakopane.if.uj.edu.pl/event/9/contributions/308/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Maxwell demons in phase space
DTSTART;VALUE=DATE-TIME:20190920T093000Z
DTEND;VALUE=DATE-TIME:20190920T100000Z
DTSTAMP;VALUE=DATE-TIME:20201031T224050Z
UID:indico-contribution-9-282@zakopane.if.uj.edu.pl
DESCRIPTION:Speakers: Juan MR Parrondo ()\nAlthough there is not a complet
e “proof” of the second law of thermodynamics based on microscopic dyn
amics\, two properties of Hamiltonian systems have been used to prove the
impossibility of work extraction from a single thermal reservoir: Liouvill
e’s theorem and the adiabatic invariance of the volume enclosed by an en
ergy shell (Helmholtz's theorem). In this talk\, I will review these two p
roperties and analyze the dynamics of isothermal and microcanonical Szilar
d engines in the phase space. In particular\, we will see that ergodicity
breaking plays a crucial role in all these variants of the Maxwell demon b
ecause the enclosed volume is no longer an adiabatic invariant in non-ergo
dic systems.\n\nhttps://zakopane.if.uj.edu.pl/event/9/contributions/282/
LOCATION:Kraków
URL:https://zakopane.if.uj.edu.pl/event/9/contributions/282/
END:VEVENT
BEGIN:VEVENT
SUMMARY:How is information decoded in developmental systems?
DTSTART;VALUE=DATE-TIME:20190920T073000Z
DTEND;VALUE=DATE-TIME:20190920T080000Z
DTSTAMP;VALUE=DATE-TIME:20201031T224050Z
UID:indico-contribution-9-338@zakopane.if.uj.edu.pl
DESCRIPTION:Speakers: Marcin Zagórski (Marian Smoluchowski Institute of P
hysics\, Jagiellonian University)\nThe development of multicellular organi
sms is a dynamic process in which cells divide\, rearrange\, and interpret
molecular signals to adopt specific cell fates. Despite the intrinsic sto
chasticity of cellular events\, the cells identify their position within t
he tissue with striking precision of one cell diameter in fruit fly or thr
ee cell diameters in vertebrate spinal cord. How do cells acquire this pos
itional information? Where is this information encoded and how do cells de
code it to achieve the observed level of cell fate reproducibility? These
are fundamental questions in biology that are still poorly understood. In
this talk\, I will combine both information theory methods and mechanistic
models to address these questions. I will investigate to what extent the
level of noise in the input signals affects precision of the resulting gen
e expression pattern. I will present data-driven analysis of gene regulato
ry network that interprets two positional cues in the developing spinal co
rd. Interestingly\, the observed precision of gene expression pattern is c
lose to the theoretical limit of precision of decoding of noisy signals.\n
\nhttps://zakopane.if.uj.edu.pl/event/9/contributions/338/
LOCATION:Kraków
URL:https://zakopane.if.uj.edu.pl/event/9/contributions/338/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Levy walk with rests: Escape from bounded domain
DTSTART;VALUE=DATE-TIME:20190920T082000Z
DTEND;VALUE=DATE-TIME:20190920T084000Z
DTSTAMP;VALUE=DATE-TIME:20201031T224050Z
UID:indico-contribution-9-337@zakopane.if.uj.edu.pl
DESCRIPTION:Speakers: Agnieszka Kamińska ()\nThe Levy walk processes with
rests restricted to a region bounded by two absorbing barriers are discu
ssed. The waiting time between the jumps is given by an exponential distri
bution with a constant jumping rate and with a position-dependent jumping
rate. The time of flight for both ranges of $\\alpha$: lower $(0\,1)$ an
d higher $(1\,2)$\, is considered.\nFor constant jumping rate two limits a
re taken into account: of short waiting time that corresponds to Levy walk
s without rests\, and long waiting time which exhibits properties of Levy
flights model. The quantities describing the escape process: first passage
time distribution\, mean first passage time are analysed. The analytical
results are compared with Monte Carlo trajectory simulations.\n\nhttps://z
akopane.if.uj.edu.pl/event/9/contributions/337/
LOCATION:Kraków
URL:https://zakopane.if.uj.edu.pl/event/9/contributions/337/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Lévy flights in steep potential wells: Langevin modeling versus d
irect reponse to energy landscapes
DTSTART;VALUE=DATE-TIME:20190920T080000Z
DTEND;VALUE=DATE-TIME:20190920T082000Z
DTSTAMP;VALUE=DATE-TIME:20201031T224050Z
UID:indico-contribution-9-312@zakopane.if.uj.edu.pl
DESCRIPTION:Speakers: Piotr Garbaczewski (University of Opole)\nThe Eliaza
r-Klafter targeted stochasticity concept \, together and that of the rever
se engineering (reconstruction of the stochastic process once a target pdf
is a priori given)\, has been originally devised for Lévy-driven Langev
in systems. Its generalization\, discussed in [PRE 84\, 011142\, (2011)
]\, involves a non-Langevin alternative which associates with the sam Levy
driver and the same target pdf\, another (Feynman-Kac formula related) c
onfinement mechanism for Lévy flights\, based on a direct reponse to ene
rgy (potential) landscapes\, instead of that to conservative forces. We r
evisit the problem of Lévy motion in steep potential wells\, addressed i
n [A.A. Kharcheva et al.\, J. Stat Mech.\, (2016)\, 054029] and [B. Dybie
c et al. \, PRE 95\, 05201\, (2017)] and discuss the alternative semig
roup (Feynman-Kac) motion scenario. Our focus is on a link with the
problem of boundary data (Dirichlet versus Neumann\, or absorbing versus
reflecting) for the Lévy motion and its generator on the interval (
or bounded domain\, in general).\n\nhttps://zakopane.if.uj.edu.pl/event/9/
contributions/312/
LOCATION:Kraków
URL:https://zakopane.if.uj.edu.pl/event/9/contributions/312/
END:VEVENT
BEGIN:VEVENT
SUMMARY:The Volterra type equation related to the non-Debye relaxation
DTSTART;VALUE=DATE-TIME:20190920T084000Z
DTEND;VALUE=DATE-TIME:20190920T090000Z
DTSTAMP;VALUE=DATE-TIME:20201031T224050Z
UID:indico-contribution-9-310@zakopane.if.uj.edu.pl
DESCRIPTION:Speakers: Katarzyna Górska (INP PAS)\nI will present the solu
tions of Volterra equations with the fading memory given by the Prabhakar
function with negative upper parameter which is relevant to the standard n
on-Debye models of dielectric relaxation\, namely for the Cole-Cole\, Cole
-Davidson\, and Havriliak-Negami models. These integro-differential equati
ons are solved by using the umbral calculus and Laplace transform method w
hose results are identically for the same fixed values of the used paramet
ers.\n\nhttps://zakopane.if.uj.edu.pl/event/9/contributions/310/
LOCATION:Kraków
URL:https://zakopane.if.uj.edu.pl/event/9/contributions/310/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Fundamental limitations of the step quantum heat engine
DTSTART;VALUE=DATE-TIME:20190919T133000Z
DTEND;VALUE=DATE-TIME:20190919T135000Z
DTSTAMP;VALUE=DATE-TIME:20201031T224050Z
UID:indico-contribution-9-307@zakopane.if.uj.edu.pl
DESCRIPTION:Speakers: Marcin Łobejko (University of Gdańsk)\nThe model o
f a step quantum heat engine (SQHE) is defined as a working body\, given b
y the two-level system (TLS)\, acting separately (i.e. in steps) with the
heat baths and the energy storage system (a battery). A single step of the
engine is defined as the unitary and energy conserving operation. For the
general SQHE we prove the fundamental attainable efficiency\, given as a
function of a cold and hot temperature\, which is below the Carnot efficie
ncy. The reason is that the engine is quasi-autonomous\, i.e. there is no
extra external control like fields commonly used in a non-autonomous setti
ng\, but in contrary the SQHE is realised by a unique physical process of
the TLS population inversion via a strong coupling with the heat bath. For
our model of the SQHE we additionally discuss the problem of the work def
inition for the fully quantum systems. So far one of the reasonable defini
tion of the work (consistent with the fluctuation theorems) is given by th
e change in a mean energy of the battery which has additionally a translat
ional symmetry\, i.e. these changes do not depend on how much energy
is currently stored in the battery. However\, this symmetry impose a no
nphysical property that the battery cannot have a ground state. We solve t
his problem showing that the battery with a ground state can be used as a
proper energy storage system only if the work is defined as a change of th
e ergotropy instead of a mean energy.\n\nhttps://zakopane.if.uj.edu.pl/eve
nt/9/contributions/307/
LOCATION:Kraków
URL:https://zakopane.if.uj.edu.pl/event/9/contributions/307/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Exact resuts on Quantum Walks
DTSTART;VALUE=DATE-TIME:20190919T123000Z
DTEND;VALUE=DATE-TIME:20190919T130000Z
DTSTAMP;VALUE=DATE-TIME:20201031T224050Z
UID:indico-contribution-9-328@zakopane.if.uj.edu.pl
DESCRIPTION:Speakers: Kirone MALLICK (IPhT\, CEASaclay France)\nQuantum an
alogs of classical random walks have been defined in quantum information t
heory as a useful concept to implement algorithms. Due to interference e
ffects\, statistical properties of quantum walks can drastically differ fr
om their classical counterparts\, leading to much faster computations.\n \
nWe shall present various statistical properties of continuous-time qua
ntum walks on a lattice\, such as: survival properties of quantum partic
les in the presence of traps (i.e. a quantum generalization of the Donsker
-Varadhan stretched exponential law)\, the growth of a quantum population
in the presence of a source\, quantum return probabilities and Loschmid
t echoes.\n\nhttps://zakopane.if.uj.edu.pl/event/9/contributions/328/
LOCATION:Kraków
URL:https://zakopane.if.uj.edu.pl/event/9/contributions/328/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Non-Hermitean and Zeno limit of the quantum first detection proble
m
DTSTART;VALUE=DATE-TIME:20190919T130000Z
DTEND;VALUE=DATE-TIME:20190919T133000Z
DTSTAMP;VALUE=DATE-TIME:20201031T224050Z
UID:indico-contribution-9-323@zakopane.if.uj.edu.pl
DESCRIPTION:Speakers: Felix Thiel (Bar-Ilan University)\nThe classical fir
st-passage theory for random walks is generalized to quantum systems by us
ing repeated attempts with a fixed frequency $1/\\tau$ to find the system
in the detection state $| \\psi_\\text{d}\\rangle$. The first successful o
f these attempts defines the time $T = N \\tau$ of first *detected* arriva
l. Here\, the Zeno limit $\\tau\\to0$ of diverging detection frequency is
investigated. The repeated detection setup is compared with a non-Hermitea
n Schrödinger equation. Using an electrostatic analogy we can determine a
ll absorbtion modes in the Zeno limit and find the pdf as well as all mome
nts of $T$ for systems with a discrete energy spectrum. The pdf has a scal
ing form in $\\tau$. Applying known results from the repeated detection se
tup to the non-Hermitean equation shows that the mean dissipation time in
the latter system is quantized.\n\nhttps://zakopane.if.uj.edu.pl/event/9/c
ontributions/323/
LOCATION:Kraków
URL:https://zakopane.if.uj.edu.pl/event/9/contributions/323/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Mimicking heterogeneous diffusion with time dependent random diffu
sivity.
DTSTART;VALUE=DATE-TIME:20190919T100000Z
DTEND;VALUE=DATE-TIME:20190919T102000Z
DTSTAMP;VALUE=DATE-TIME:20201031T224050Z
UID:indico-contribution-9-334@zakopane.if.uj.edu.pl
DESCRIPTION:Speakers: Vittoria Sposini (University of Potsdam (Germany) &
BCAM (Spain))\nA considerable number of systems have recently been report
ed in which Brownian yet non-Gaussian dynamics was observed. These are pro
cesses characterised by a linear growth in time of the mean squared displa
cement\, yet the probability density function of the particle displacement
is distinctly non-Gaussian\, and often of exponential (Laplace) shape. Th
is behaviour has been interpreted as resulting from diffusion in inhomogen
eous environments and mathematically represented through a variable\, stoc
hastic diffusion coefficient. Indeed different models describing a fluctua
ting diffusivity have been studied. In particular\, we focus on the theory
of diffusing diffusivity and consider the very generic class of the gener
alised Gamma distribution for the random diffusion coefficient. Moreover\,
addressing the first passage problem for a specific diffusing diffusivity
model\, we emphasize that even when the non-Gaussian character appears fo
r certain regimes only and in the tails of the distributions (thus with lo
w probability)\, it may be essential for those systems in which rare event
s dominate triggered actions.\n\nhttps://zakopane.if.uj.edu.pl/event/9/con
tributions/334/
LOCATION:Kraków
URL:https://zakopane.if.uj.edu.pl/event/9/contributions/334/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Cross-diffusion in concentrated reactive systems revealed by pertu
rbation of FKPP wave front
DTSTART;VALUE=DATE-TIME:20190919T104000Z
DTEND;VALUE=DATE-TIME:20190919T110000Z
DTSTAMP;VALUE=DATE-TIME:20201031T224050Z
UID:indico-contribution-9-304@zakopane.if.uj.edu.pl
DESCRIPTION:Speakers: Gabriel Morgado (Institute of Physical Chemistry - P
AN / Sorbonne Universite)\nThe sensitivity to perturbations of the Fisher\
, Kolmogorov\, Petrovskii\, and Piskunov (FKPP) wave front is used to find
a quantity revealing the perturbation of diffusion in a concentrated solu
tion. We consider two chemical species A and B engaged in the reaction A +
B $\\rightarrow$ 2A. When A and B have different diffusivities $D_A$ and
$D_B$\, the deterministic dynamics includes cross-diffusion terms due to t
he deviation from the dilution limit [1].\n\nThe behaviors of the front sp
eed\, the shift between the concentration profiles of the two species\, an
d the width of the reactive zone are investigated\, both analytically and
numerically. The analytic results are deduced from a perturbation approach
in the limit of small diffusion terms with respect to reaction terms. The
shift between the two profiles turns out to be a well-adapted criterion p
resenting noticeable variations with the deviation from the dilution limit
in a wide range of parameter values. In particular\, the difference betwe
en the shifts obtained in a dilute system and a concentrated system increa
ses as $D_B$ differs from $D_A$\, especially in the case $D_B>D_A$ [2]. \n
\n[1] L. Signon\, B. Nowakowski\, and A. Lemarchand\, Phys. Rev. E **93**\
, 042402 (2016).\n[2] G. Morgado\, B. Nowakowski\, and A. Lemarchand\, Phy
s. Rev. E **99**\, 022205 (2019).\n\nhttps://zakopane.if.uj.edu.pl/event/9
/contributions/304/
LOCATION:Kraków
URL:https://zakopane.if.uj.edu.pl/event/9/contributions/304/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Thermodynamic Efficiency in Dissipative Chemistry
DTSTART;VALUE=DATE-TIME:20190919T102000Z
DTEND;VALUE=DATE-TIME:20190919T104000Z
DTSTAMP;VALUE=DATE-TIME:20201031T224050Z
UID:indico-contribution-9-302@zakopane.if.uj.edu.pl
DESCRIPTION:Speakers: Emanuele Penocchio (University of Luxembourg)\nChemi
cal processes in closed systems inevitably relax to equilibrium. Living sy
stems avoid this fate and give rise to a much richer diversity of phenomen
a by operating under nonequilibrium conditions. Recent experiments in diss
ipative self-assembly also demonstrated that by opening reaction vessels a
nd steering certain concentrations\, an ocean of opportunities for artific
ial synthesis and energy storage emerges. To navigate it\, thermodynamic n
otions of energy\, work and dissipation must be established for these open
chemical systems. Here\, we do so by building upon recent theoretical adv
ances in nonequilibrium statistical physics. As a central outcome\, we sho
w how to quantify the efficiency of such chemical operations and lay the f
oundation for performance analysis of any dissipative chemical process.\n\
nhttps://zakopane.if.uj.edu.pl/event/9/contributions/302/
LOCATION:Kraków
URL:https://zakopane.if.uj.edu.pl/event/9/contributions/302/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Of Brains and Markets
DTSTART;VALUE=DATE-TIME:20190919T093000Z
DTEND;VALUE=DATE-TIME:20190919T100000Z
DTSTAMP;VALUE=DATE-TIME:20201031T224050Z
UID:indico-contribution-9-286@zakopane.if.uj.edu.pl
DESCRIPTION:Speakers: Reimer Kuehn (Department of Mathematics\, King's Col
lege London)\nIn this talk\, we explore an approach to understanding price
fluctuations within a market via considerations of functional dependencie
s between asset prices. Interestingly\, this approach suggests a class of
models of a type used earlier to describe the dynamics of real and artific
ial neural networks. Statistical physics approaches turn out to be suitabl
e for an analysis of their collective properties. We first motivate the ba
sic phenomenology and modeling arguments before moving on to discussing so
me major issues with inference and empirical verification. In particular\,
we focus on the natural creation of market states through the inclusion o
f interactions and how these then interfere with inference. This is primar
ily addressed in a synthetic setting. Finally we investigate real data to
test the ability of our approach to capture some key features of the behav
ior of financial markets.\n\nhttps://zakopane.if.uj.edu.pl/event/9/contrib
utions/286/
LOCATION:Kraków
URL:https://zakopane.if.uj.edu.pl/event/9/contributions/286/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Fluctuation Theorems for Systems without Stationary PDF: KPZ case
DTSTART;VALUE=DATE-TIME:20190919T080000Z
DTEND;VALUE=DATE-TIME:20190919T082000Z
DTSTAMP;VALUE=DATE-TIME:20201031T224050Z
UID:indico-contribution-9-331@zakopane.if.uj.edu.pl
DESCRIPTION:Speakers: Horacio S. Wio (Institute for Cross-Disciplinary Phy
sics and Complex Systems)\nWe analyze a couple of simple systems\, without
stationary probability distribution\, in order to show how to proceed fo
r obtaining detailed as well as integral fluctuation theorems in such a ki
nd of systems. To reach such a goal\, we exploit a path integral approach
that adequately fits to this kind of study. This methodology\, together wi
th the variational approach\, are also exploited to analize fluctuation th
eorems in the paradigmatic KPZ equation\, as well as to determine a Large
Deviation Function. This lead us to conjecture that a higher critical dime
nsion does not exists for the KPZ system.\n\nhttps://zakopane.if.uj.edu.pl
/event/9/contributions/331/
LOCATION:Kraków
URL:https://zakopane.if.uj.edu.pl/event/9/contributions/331/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Active Interface Equations
DTSTART;VALUE=DATE-TIME:20190919T073000Z
DTEND;VALUE=DATE-TIME:20190919T080000Z
DTSTAMP;VALUE=DATE-TIME:20201031T224050Z
UID:indico-contribution-9-322@zakopane.if.uj.edu.pl
DESCRIPTION:Speakers: Martin Evans (University of Edinburgh)\nIn this work
we consider the role of active inclusions in a growing interface\, for ex
ample membrane binding proteins which catalyse growth in the plasma membra
ne of eukaryotic cells. The interface is thus rendered active and is desc
ribed by two coupled fields: the height field of the interface and the den
sity of the inclusions. The equations generalise to active interface grow
th the Kardar Parisi Zhang equation which descibes nonequilibrium growth a
nd also represents many other systems driven out of out of equilibrium. I
n our model inclusions gravitate towards minima of the height field and th
en catalyse growth which generates interface waves. This leads to complex
kinematic waves and pattern formation and the proteins are able to surf th
e waves they create. The interface width displays a novel superposition o
f scaling and sustained oscillations distinct from KPZ physics.\n\nF Cagne
tta\, M. R. Evans and D Marenduzzo Phys. Rev. Lett. 120\, 258001 (2018)\
nF Cagnetta\, M. R. Evans and D Marenduzzo Phys. Rev. E 99\, 042124 (201
9)\n\nhttps://zakopane.if.uj.edu.pl/event/9/contributions/322/
LOCATION:Kraków
URL:https://zakopane.if.uj.edu.pl/event/9/contributions/322/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Single particle diffusion in periodic potentials
DTSTART;VALUE=DATE-TIME:20190919T084000Z
DTEND;VALUE=DATE-TIME:20190919T090000Z
DTSTAMP;VALUE=DATE-TIME:20201031T224050Z
UID:indico-contribution-9-284@zakopane.if.uj.edu.pl
DESCRIPTION:Speakers: Oded Farago (Ben Gurion University)\nWe calculate th
e time-dependent probability distribution function (PDF) of an overdamped
Brownian particle moving in a one-dimensional periodic potential energy $U
(x)$. The PDF is found by solving the corresponding Smoluchowski diffusion
equation. We derive the solution for any periodic even function $U(x)$ an
d demonstrate that it is asymptotically (at large times $t$) correct up to
terms decaying faster than $1/t^{3/2}$. As part of the derivation\, we al
so recover the Lifson-Jackson formula for the effective diffusion coeffici
ent of the dynamics. The derived solution exhibits agreement with Langevin
dynamics simulations. The approach is generalized for inhomogeneous syste
ms where\, in additional to the periodic potential\, the particle also exp
eriences a periodic diffusion coefficient. The application of a one-dimens
ional (Fick-Jacobs) diffusion equation for describing Brownian dynamics in
periodic corrugated channels is also discussed.\n\nhttps://zakopane.if.uj
.edu.pl/event/9/contributions/284/
LOCATION:Kraków
URL:https://zakopane.if.uj.edu.pl/event/9/contributions/284/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Competition between cancer and immune system cells in an inhomogen
eous system: A thermostatted kinetic theory approach
DTSTART;VALUE=DATE-TIME:20190919T082000Z
DTEND;VALUE=DATE-TIME:20190919T084000Z
DTSTAMP;VALUE=DATE-TIME:20201031T224050Z
UID:indico-contribution-9-283@zakopane.if.uj.edu.pl
DESCRIPTION:Speakers: Annie Lemarchand (Sorbonne Université\, CNRS)\nThe
treatment of cancer by boosting the immune system is a recent and promisin
g therapeutic strategy. During interactions\, the immune system cells lear
n to recognize cancer cells. Analogously\, the cancer cells can develop th
e ability to blend into the surrounding tissue and mislead the immune syst
em cells.\n\nI will present a model of cell interactions in the framework
of thermostatted kinetic theory [1\,2]. Cell activation\, learning process
es\, and memory loss due to cell death are reproduced by regulating the ce
ll activity introduced in the model. By analogy with energy dissipation in
a mechanical system\, the control of the activity fluctuations is achieve
d by a so-called thermostat. Proliferation of cancer cells is reproduced b
y autocatalytic processes. For each cell type\, I will write down the ther
mostatted kinetic equations for the distribution functions of position\, v
elocity\, and activity and explain how the direct simulation Monte Carlo (
DSMC) method has been adapted to solve them.\n\nThe numbers and activities
of cancer cells and immune system cells are followed for different initia
l distributions of cells. The effect of the thermostat on cancer evolution
will be compared to unexplained clinical observations. I will show that t
he model is able to reproduce an apparent elimination of the tumor precedi
ng a long period of equilibrium\, eventually followed by the proliferation
of the cancer cells\, according to a process identified as "the three E's
" of immunoediting\, for "Elimination\, Equilibrium and Escape" [3\,4].\n\
n1. C. Bianca and A. Lemarchand\, Commun. Nonlinear Sci. Numer. Simul. 20\
, 14 (2015).\n2. C. Bianca\, C. Dogbe\, and A. Lemarchand\, Acta Appl. Mat
h. 189\, 1 (2015).\n3. C. Bianca and A. Lemarchand\, J. Chem. Phys. 145\,
154108 (2016).\n4. L. Masurel\, C. Bianca\, and A. Lemarchand\, Physica A
506\, 462 (2018).\n\nhttps://zakopane.if.uj.edu.pl/event/9/contributions/2
83/
LOCATION:Kraków
URL:https://zakopane.if.uj.edu.pl/event/9/contributions/283/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Stochastic Resetting
DTSTART;VALUE=DATE-TIME:20190918T153000Z
DTEND;VALUE=DATE-TIME:20190918T160000Z
DTSTAMP;VALUE=DATE-TIME:20201031T224050Z
UID:indico-contribution-9-319@zakopane.if.uj.edu.pl
DESCRIPTION:Speakers: Satya Majumdar (CNRS\, LPTMS\, Universite Paris-Sud
(Orsay)\, France)\nEvolving stochastic process\, when interrupted at rando
m epochs and reset to its initial condition\, reaches a new nonequilibrium
stationary state. The approach to the stationary state is accompanied by
an unusual `dynamical phase transition'. Moreever\, the mean first-passage
time to a fixed target becomes a minimum at an optimal value of the reset
ting rate. This makes the diffusive search process rather efficient. Reset
ting dynamics has been studied intensively in the last few years and is a
rapidly emerging field in stochastic processes and nonequilibrium systems.
In this talk\, I'll give an overview of this evolving field.\n\nhttps://z
akopane.if.uj.edu.pl/event/9/contributions/319/
LOCATION:Kraków
URL:https://zakopane.if.uj.edu.pl/event/9/contributions/319/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Introduction to the quantum first detection problem
DTSTART;VALUE=DATE-TIME:20190918T150000Z
DTEND;VALUE=DATE-TIME:20190918T153000Z
DTSTAMP;VALUE=DATE-TIME:20201031T224050Z
UID:indico-contribution-9-317@zakopane.if.uj.edu.pl
DESCRIPTION:Speakers: Eli Barkai (Bar-Ilan University)\nWe consider quantu
m dynamics on a graph\, with repeated strong measurements performed locall
y at a fixed time interval $\\tau$. For example a particle starting on no
de $x$ and measurements performed on another node $x'$. From the basic pos
tulates of quantum mechanics the string of measurements yields a sequence
no\,no\,no\, $\\cdots$ and finally in the $n$-th attempt a yes\, i.e. the
particle is detected. Statistics of the first detection time $n \\tau$ ar
e investigated\, and compared with the corresponding classical first passa
ge problem. Dark states\, Zeno physics\, a quantum renewal equation\, wind
ing number for the first return problem (work of A. Grunbaum et al.)\, to
tal detection probability\, detection time operators and time wave functio
ns are discussed.\n\nhttps://zakopane.if.uj.edu.pl/event/9/contributions/3
17/
LOCATION:Kraków
URL:https://zakopane.if.uj.edu.pl/event/9/contributions/317/
END:VEVENT
END:VCALENDAR