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Wittenberg 2015
Table of contents
Scientific program – overview
Timetables and abstracts
Monday
Tuesday
Wednesday
List of posters and poster abstracts
Venue
Excursions
List of participants
5
7
15
25
33
51
53
55
Organizer:
Collaborative Research Center 910: “Control of self-organizing
nonlinear systems: Theoretical methods and concepts of application”
http://www.tu-berlin.de/?wittenberg15
Organizing Committee:
Philipp Hövel (TU Berlin), Chair
Anna Zakharova (TU Berlin), Chair
Roland Aust (TU Berlin), Conference Secretary
Yulia Jagodzinski (TU Berlin)
Pavel Gurevich (FU Berlin), Program Committee
Kathy Lüdge (FU Berlin), Program Committee
Serhiy Yanchuk (WIAS Berlin), Program Committee
Jakub Sawicki (TU Berlin), Musical Chair
Stanislav Ax (TU Berlin), Technical Chair
3
Settle in, coffee
Welcome address
K. Showalter (invited)
Lunch
I. Omelchenko (A1)
A.V. Slepnev (B11)
S. Gerloff (B2)
Coffee break
P. Kalle (B4)
S. Martens (B6)
T. Niedermayer (B5)
Coffee break
Poster session
19:00 Dinner
20:30 Conference concert
11:15
11:30
11:50
12:35
14:00
14:20
14:40
15:00
15:30
15:50
16:10
16:30
16:50
Bus travel from parking lot
Zoologischer Garten
Berlin → Wittenberg
10:30 Arrival
8:30
Monday,
September 14th
16:00 Excursions
18:30
19:00 Conference Dinner
14:00
14:45
15:05
15:30
8:00
9:00
9:45
10:15
10:35
10:55
11:15
11:45
12:05
12:25
Tuesday,
September 15th
Breakfast
J. Danckaert (invited)
Coffee break
A. Röhm (B9)
J. Kabuß (B1)
G. Engelhardt (A7)
Coffee break
S. Reichelt (A5)
I. Schneider (A4)
Group photo
Lunch
L. Larger (invited)
D. Puzyrev (A3)
Coffee break
Meeting of Principal
Investigators
18:00 Arrival in Berlin
15:30 Departure by bus
14:45 Closing remarks
8:00
9:00
9:45
10:15
10:35
10:55
11:25
11:45
12:05
12:25
14:00
Wednesday,
September 16th
Breakfast
Y. Kyrychko (invited)
Coffee break
A. Koher (B10)
J. Ladenbauer (B8)
Coffee break
R. Lasarzik (A8)
V. Mehrmann (A2)
M. Curran (A9)
Lunch
Martin Brokate (invited)
Wittenberg 2015
Program schedule – overview
5
Wittenberg 2015
Program schedule – Monday
Monday, September 14th
Chair: Anna Zakharova
11:30
11:50
12:35
Welcome address
Ken Showalter (West Virginia University, USA) (invited)
Synchronization in networks of coupled chemical oscillators
Lunch
Chair: Philipp Hövel
14:00
14:20
14:40
15:00
Iryna Omelchenko (Technische Universität Berlin, Germany) (A1)
The facets of chimera states
Andrei Slepnev (Saratov State University, Saratov, Russia) (B11)
Chimeras, traveling waves, and antiphase synchronization areas in a ring
of non-locally coupled Anishchenko – Astakhov self-sustained oscillators
Sascha Gerloff (Technische Universität Berlin, Germany) (B2)
Local transport via density excitations in confined colloidal mixtures
under shear flow
Coffee break
Chair: Iryna Omelchenko
15:30
16:30
16:50
Peter Kalle (Technische Universität Berlin, Germany) (B4)
Controlling the dynamics of complex fluids by time-delayed feedback
Steffen Martens (Technische Universität Berlin, Germany) (B6)
Position control of traveling dissipative solitons
Thomas Niedermayer (Physikalisch-Technische Bundesanstalt, Germany) (B5)
Optimal defibrillation – an example for control of excitation waves
in a multiscale system
Coffee break
Poster session
19:00
20:30
Dinner
Conference concert
15:50
16:10
7
Invited talk
Wittenberg 2015 Abstract
Synchronization in Networks of Coupled Chemical Oscillators
Kenneth Showalter∗
∗
West Virginia University
Electronic Address: [email protected]
We have studied heterogeneous populations of chemical oscillators to characterize different types of synchronization behavior. We describe the formation of phase clusters
and chimera states in populations of photosensitive oscillators. The nonlocal coupling
occurs via illumination intensity that is dependent on the state of each oscillator. We
then describe studies of phase-lag synchronization in networks of photochemically coupled
oscillators, where the influence of permutation symmetries is explored.
[1] A. F. Taylor et al., Angewandte Chemie Int. Ed. 50, 10161 (2011).
[2] M. R. Tinsley et al., Nature Physics 8, 662 (2012).
[3] S. Nkomo et al., Phys. Rev. Lett. 110, 244102 (2013).
8
Contributed talk
The facets of chimera states
Iryna Omelchenko∗ , Anna Zakharova, Eckehard Schöll
Institut für Theoretische Physik, Technische Universität Berlin, Germany
∗ Electronic Address: [email protected]
Systems of nonlocally coupled oscillators can exhibit complex spatiotemporal patterns,
called chimera states, which consist of coexisting domains of spatially coherent and incoherent dynamics. First observed in the systems of identical elements with symmetric
coupling topology, chimera states have been intensively studied during the last decade.
Recent studies have shown that the concept of a chimera state can be extended to a
broader range of systems and topologies.
We study novel facets of chimera states: robustness and dependence on the nonlinearity
of local dynamics. We discuss the robustness of chimera states in systems of nonidentical elements with regular coupling topology, and in systems of identical elements with
irregular coupling topologies. We compare how these two types of inhomogeneities influence the chimera states, and demonstrate their robustness [1]. Our investigations are
focused on the systems of coupled FitzHugh-Nagumo and Van der Pol oscillators. We
also analyse the impact of local dynamics on the occurrence of chimera states in the
system, regimes of their stability in the parameter space, and uncover the influence of
time delay introduced in the coupling [2].
This work is in collaboration with Astero Provata, Johanne Hizanidis, Julien Siebert,
Philipp Hövel.
[1] I. Omelchenko, A. Provata, J. Hizanidis, E. Schöll, P. Hövel. Phys. Rev. E 91,
022917 (2015).
[2] I. Omelchenko, A. Zakharova,
ArXiv:1503.03377 (2015).
P.
Hövel,
J.
Siebert,
and
E.
Schöll.
9
Contributed talk
Chimeras, Traveling Waves, and Antiphase Synchronization
Areas in a Ring of Non-Locally Coupled Anishchenko –
Astakhov Self-Sustained Oscillators
A.V. Slepnev∗ , T.E. Vadivasova, V.S. Anishchenko
∗
Saratov State University, Saratov, Russia
A ring of non-locally coupled Anishchenko – Astakhov self-sustained oscillators is studied. Such a system can be described by the following equations:

P
σ i+P
dxi


= mxi + yi − xi zi +
(xj − xi ),


dt
2P

j=i−P


i+P
P
dyi
σ
= −xi +
(yj − yi ),

 dt
2P j=i−P




 dzi = g(Φ(x ) − z ),
i
i
dt x
Φ (x) = (x + |x|) ,
2
i = 1, 2, . . . , N,
(1)
where m and g are the control parameters, σ is the coupling strength, P is the number
of coupled neighbors, N is the number of elements in the ring.
The existence of chimera states is demonstrated for the system (1) in the chaotic regime.
The peculiarities of the chimera state origination and the temporal behavior of elements
both in the coherent and incoherent areas of the chimera are discussed. The coherence
regions are plotted in the (r, σ) parameter plane, where r = P/N is the coupling radius.
The study was partially supported by RFBR (research project No. 14-52-12002) and
by the Russian Ministry of Education and Science (project code 1008).
10
Contributed talk
Local transport via density excitations in confined colloidal
mixtures under shear flow
Sascha Gerloff∗ , Tarlan A. Vezirov, Sabine H. L. Klapp
Institut für Theoretische Physik, Technische Universität Berlin, Hardenbergstraße 36,
10623 Berlin, Germany
Driving crystalline surfaces against each other displays a vast variety of complex nonlinear dynamics [1]. For small driving forces, the dynamics of the surfaces are dominated
by a local transport mechanism provided by topological defects. In order to understand
the frictional response of the surfaces, the dynamics and properties of these topological
defects are of great interest.
Here, we investigate the sliding dynamics of colloidal crystal layers of two different species,
which are induced by a strong slit-pore confinement and stabilized by a constant demixing force. The colloids interact via a combined soft-sphere and screened Coulomb
interaction with parameters suitable to model ludox-silica particles. As in previous studies of the one-component system, the colloids are driven by a planar shear flow [2, 3].
Overdamped Brownian dynamics are employed, allowing a detailed examination of the
local dynamics of the topological defects. These are identified as clusters of high and low
local density, forming density excitations. One key result is the connection between the
velocity of the layer and the velocity as well as amount of density excitations, displaying
a strong dependence of the velocity of the layer on the amount of density excitations.
Furthermore, novel dynamics for low local density excitations are observed, which can be
explained by elastic deformations of the adjacent colloidal crystal layers. Moreover, we
are interested in the general influence of the deformable substrate, altering the dynamics
and nucleation of topological defects.
Potentially by obtaining a deep understanding of this mechanism, we aim to develop
feedback control strategies, allowing to alter the frictional response of the considered
system and therefore following previous studies on applying feedback control schemes to
soft matter systems [3].
[1] T. Bohlein, J. Mikhael and C. Bechinger, Nat. Mater. 11, 126-130 (2012)
[2] T. A. Vezirov and S. H. L. Klapp, Phys. Rev. 88, 052307 (2013)
[3] T. A. Vezirov, S. Gerloff and S. H. L. Klapp, Soft Matter 11, 406-413 (2015)
11
Contributed talk
Controlling the dynamics of complex fluids by time-delayed
feedback
Peter Kalle∗ , Maria Zeitz, Jenny Triptow, Holger Stark
Institut fuer Theoretische Physik, TU Berlin, Berlin, Germany
Soft materials or complex fluids strongly respond to external fields and thereby show
prominent non-equilibrium structure formation. Applying specific control strategies to
shape and engineer the flow of Newtonian and complex fluids on the micron scale virtually
is an unexplored field. We study control strategies to manipulate and induce novel
motional flow patterns in different models of complex liquids. The models we consider are
a Newtonian fluid in the limit of small Reynolds numbers where the nonlinear convectionterm is negligible, the two-fluid model where the Navier-Stokes equations are coupled to
an additional permeation term and the nonlinear Oldroyd B model where intrinsic elastic
instabilites can occur, even in the limit of low Reynolds numbers.
12
Contributed talk
Position control of traveling dissipative solitons
Steffen Martens1∗ , Christopher Ryll2 , Fredi Tröltzsch2 , Harald Engel1
1
2
Technische Universität Berlin, Institut für Theoretische Physik, 10623 Berlin,
Germany
Technische Universität Berlin, Institut für Mathematik, 10623 Berlin, Germany
Besides travelling waves, moving localized spots – also called dissipative solitons – represent yet another important class of self-organized spatio-temporal structures in nonequilibrium dissipative systems in two spatial dimensions. These moving localized structures can be found either in two-component reaction-diffusion-systems with a global feedback term [1] or in three-component systems like the well-studied Purwins model [2]
∂t u (x, t) = λu (x, t) − u (x, t)3 + k1 − k2 v (x, t) − k3 w (x, t) + Du ∆u (x, t) ,
τ ∂t v (x, t) = u (x, t) − v (x, t) + Dv ∆v (x, t) ,
Θ∂t w (x, t) = u (x, t) − w (x, t) + Dw ∆w (x, t) ,
(1)
x ∈ R2 .
While the particle-like features of localized spot solutions to Eqs. (1) have been widely
investigated [3], in this talk we focus attention to control aspects and present an efficient
method to control the position of these moving localized structures according to a given
protocol of movement. In detail, we present two different approaches to guide a localized
spot along a pre-given trajectory. First, an analytical solution for the control – being
an open-loop control – is proposed which attempts to shift the spot’s “center of mass”
according to a given protocol of movement without disturbing its profile [4]. The control
signal is expressed in terms of the uncontrolled spot profile and its propagation velocity; rendering detailed informations about the reaction kinetics unnecessary. Secondly,
the standard formulation of optimal control with an objective functional involving the
Tikohonov regularization, a L2 -norm of the control, is used. Noteworthy, our analytical
solution for the control coincides with optimal control for vanishing regularization term.
[1] K. Krischner and A. Mikhailov, Phys. Rev. Lett., 73, 3165 (1994).
[2] H.G. Purwins et al., Lect. Notes Phys. 661, 267–308 (2005).
[3] Y. Nishiura et al., Chaos 15, 047509 (2005).
[4] J. Löber and H. Engel, Phys. Rev. Lett. 112, 148305 (2014).
13
Contributed talk
Optimal defibrillation – an example for control of excitation
waves in a multiscale system
Pavel Buran, Thomas Niedermayer∗ , Markus Bär
∗
Physikalisch-Technische Bundesanstalt
Rotating spirals as well as spiral turbulence in the cardiac tissue have been associated
with arrhythmias like the life-threatening ventricular fibrillation. The termination of
these waves by an electrical shock (defibrillation) is an effective therapy, but suffers from
various adverse effects. Recent experimental studies have shown that a sequence of pulses
can terminate fibrillation more gently than a single pulse. In order to find an optimal
defibrillation protocol, we performed extensive simulations. It turns out that the period
between pulses has a crucial influence on the defibrillation success and that the optimal
period is similar to the refractory period of the cells. In addition, a feedback control that
terminates the sequence of defibrillation pulses improves the efficiency of the procedure.
We discuss these findings in the context of excitable media and more general models of
cardiac tissue.
14
Wittenberg 2015
Program schedule – Tuesday
Tuesday, September 15th
Chair: Kathy Lüdge
9:00
9:45
Jan Danckaert (Vrije Universiteit Brussel, Belgium) (invited)
Implementations and simulations of reservoir computing based
on delayed feedback systems
Coffee break
Chair: Dmitry Puzyrev
10:15
10:35
10:55
11:15
André Röhm (Technische Universität Berlin, Germany) (B9)
Semiconductor laser networks and reservoir computing
Julia Kabuß (Technische Universität Berlin, Germany) (B1)
Coherent quantum control beyond the single excitation limit
Georg Engelhardt (Technische Universität Berlin, Germany) (A7)
Topological Bogoliubov excitations in inversion-symmetric systems
of interacting bosons
Coffee break
Chair: André Röhm
11:45
12:05
12:25
Sina Reichelt (Weierstraß-Institut Berlin, Germany) (A5)
Homogenization of Cahn–Hilliard equations
Isabelle Schneider (Freie Universität Berlin, Germany) (A4)
Applying equivariant Pyragas control to our SFB logo
Group photo & lunch
Chair: Serhiy Yanchuk
15:05
15:30
Laurent Larger (FEMTO-ST / Optics dept. P.M. Duffieux, Besançon, France)
Virtual space-time delay dynamics and their chimera states (invited)
Dmitry Puzyrev (WeierstraßInstitut Berlin, Germany) (A3)
Multistability and bifurcations of laser cavity solitons induced
by delayed feedback
Coffee break
Meeting of Principal Investigators
16:00
Excursions
19:00
Conference dinner
14:00
14:45
15
Invited talk
Implementations and simulations of Reservoir Computing based
on delayed feedback systems
J. Danckaert∗ , R.M. Nguimdo, L. Keuninckx, G. Verschaffelt, G. Van der Sande
Applied Physics research group (APHY), Vrije Universiteit Brussel (VUB), Brussels,
Belgium
Reservoir computing (RC) is a bio-inspired research line in machine learning, also
known as Echo State Networks, or Liquid State Machines. In classical RC, the input is
coupled via a randomly-connected input layer to a large amount of nodes in the network
(the “reservoir”). The connections between reservoir nodes are randomly chosen and kept
fixed, i.e. the reservoir is left untrained. The reservoir’s transient dynamical response
is read out by an output layer in which the node states are linearly combined through
weighted sums of these states. The weights of the output layer are optimized in the
training procedure.
It has been shown in 2011 [1] that a single nonlinear node with delayed feedback can
substitute for an entire network of hundreds or more of nodes, maintaining similar information processing power for classification and prediction tasks. Such a delay-based
implementation facilitates experimental realisations of such networks, and can be electronic, opto-electronic as well as photonic.
We introduce the concept of delay-based Reservoir Computing [1], and discuss the
state-of-the-art performance for different implementations (electronic [1], opto-electronic
[2, 3], photonic [4, 5]) and for different tasks. We will show that the fast time scales
that typically govern the dynamics of photonic systems, lead to fast processing speeds
in photonic RC implementations [6]. We will also discuss how different optical modes in
photonic RC systems can be used to simultaneously process several, independent tasks
[7]. We will review experimentally obtained results and compare these with simulations,
and discuss where there are still opportunities for improvement, as well as challenges
(such as the effect of noise [8]) to be tackled in order to solve real world tasks.
[1] L. Appeltant et al., Nat. Commun. 2, 468 (2011).
[2] L. Larger et al., Opt. Express 20, 3241 (2012).
[3] Y. Paquot et al., Sci. Rep. 2, 287 (2012).
[4] F. Duport, et al., Opt. Express 20, 22783 (2012).
[5] D. Brunner, et al., Nat. Commun. 4, 1364 (2013).
[6] R.M. Nguimdo, et al., Opt Express 22, 8672 (2014).
[7] R.M. Nguimdo, et al., IEEE Trans. Neural Netw. Learn. Syst. accepted (2015).
[8] Soriano, et al., IEEE Trans. Neural Netw. Learn. Syst. 26 388 (2014).
16
Contributed talk
Semiconductor Laser Networks and Reservoir Computing
A. Röhm1∗ , F. Böhm1 , K. Lüdge2
2
1 Institut für Theoretische Physik, TU Berlin, 10623 Berlin
Institut für Theoretische Physik, Freie Universität Berlin, 14195 Berlin
Semiconductor lasers possess a variety of advantages, such as their intrinsic speed and
inexpensive mass fabrication. They can be expected to become vital elements of a future
generation of information processing and transmission systems, as modern fabrication
and growth methods allow for complex integrated circuits to be created on a single chip.
In this context, ’all optical computing’ describes the goal of replacing the core elements of electronic computers with corresponding photonic elements. The transistors in
the central processing unit (CPU) of contemporary computers are well suited for executing boolean operations. However, parallel to this already well-established information
processing scheme, an approach inspired by the human brain is the topic of current research. As opposed to the boolean logic of the CPU, these ’artificial neural networks’
can operate on continuous input signals. They are analog computers, i.e. transforming a
continuous input into a desired output. A promising scheme for this type of computing
is the so called ’reservoir computing’, also called ’echo state network’ [1] or ’liquid state
machine’[2]. Reservoir computing was developed for machine learning and has already
been used for spoken digit recognition [3, 4] and chaotic time series prediction [5, 4]
among others. Its appeal lies in the simplicity by which the learning algorithm can be
implemented, enabling its use without the need for highly specialized mathematical tools.
In this work we present our results on the complex dynamics of semiconductor laser
based networks and investigate their potential for reservoir computing tasks, intended as
a model for future generation optical computers.
[1] H. Jaeger, “The ’echo state’ approach to analysing and training recurrent neural
networks,” GMD - German National Research Institute for Computer Science, GMD
Report 148, 2001.
[2] W. Maass, T. Natschläger, and H. Markram, “Real-time computing without stable
states: A new framework for neural computation based on perturbations,” Neural
Comp., vol. 14, p. 2531, 2002.
[3] R. Martinenghi, S. Rybalko, M. Jacquot, Y. K. Chembo, and L. Larger, “Photonic
Nonlinear Transient Computing with Multiple-Delay Wavelength Dynamics,” Phys.
Rev. Lett., vol. 108, p. 244101, 2012.
[4] L. Larger, M. C. Soriano, D. Brunner, L. Appeltant, J. M. Gutierrez, L. Pesquera,
C. R. Mirasso, and I. Fischer, “Photonic information processing beyond turing: an
optoelectronic implementation of reservoir computing,” Opt. Express, vol. 20, no. 3,
pp. 3241–3249, 2012.
[5] K. Vandoorne, P. Mechet, T. Van Vaerenbergh, M. Fiers, G. Morthier, D. Verstraeten, B. Schrauwen, J. Dambre, and P. Bienstman, “Experimental demonstration of reservoir computing on a silicon photonics chip,” Nature Photonics, vol. 5,
no. 3541, 2014.
[6] F. Böhm, A. Zakharova, E. Schöll, and K. Lüdge, “Amplitude-phase coupling drives
chimera states in globally coupled laser networks,” Phys. Rev. E, vol. 91, no. 4, p.
040901 (R), 2015.
17
Contributed talk
Coherent Quantum Control Beyond the Single Excitation Limit
J. Kabuß1∗ , A. Carmele1 , S. Hein1 , N. Naumann1 , M. Kraft1 , L. Droenner1 ,
W.W. Chow2 , A. Knorr1
1
TU Berlin, Institut für Theoretische Physik, Hardenbergstr. 36, 10623 Germany
2 Sandia National Laboratories, Albuquerque, NM 87185-1086, USA
In our presentation, we discuss theoretical models of coherent quantum control with
applications to optomechanical systems and cavity quantum electrodynamics (cQED).
Our goal is to bridge the gap between the semi-classical description of phonon and photon
emission processes with their quantum mechanical based counterparts. In this transition
regime, both quantum fluctuations and strong acoustical/optical fields coexist and render
the problem challenging for non-perturbative approaches. Here, we start by reviewing
our analytical understanding of phonon lasing [1] and coherent quantum control of selffeedback stabilized Rabi oscillations [2]. Given the insights, how to treat and model
quantum mechanically delay differential equations of motions, we proceed by discussing
how to go beyond this single emitter/single excitation limit:
(i) For optomechanical systems, we expand our proposal for a quantum dot based
phonon laser to a many-emitter description and discuss correlated emission dynamics and
superradiant effects [3]. Furthermore, we present an intriguing analogy between typical
optomechanical setups [4] with the Fröhlich coupling in semiconductor bulk materials
with the possibility of engineering on-chip optomechanics.
(ii) For cQED systems, we present an operator based description of feedback in the
Heisenberg picture. By expanding the time-delay differential equations in a hierarchy of
time correlated expectation values, factorization techniques become possible and allow
for a microscopic substantiated semi-classical description of quantum self-feedback.
Supported by our first results, the field of coherent quantum self-feedback offers a wide
range of relevant applications and enables a new way to study fundamental quantum
optical phenomena, e.g. state selective quantum network protocols via feedback control
[5].
[1] J. Kabuß, A. Carmele and, A. Knorr, Phys. Rev. B 88, 064305 (2013)
[2] J. Kabuß, D. O. Krimer, S. Rotter, K. Stannigel, A. Knorr, and A. Carmele,
arXiv:1503.05722. (2015)
[3] L. Droenner and J. Kabuß, SPIE OPTO 93570P (2015) and in preparation
[4] N.L. Naumann, S.M. Hein, A. Knorr, and J. Kabuß, Phys. Rev. A, 90, 043835 (2014)
[5] S. M. Hein, F. Schulze, A. Carmele, and A. Knorr, Phys. Rev. A, 91 052321 (2015).
18
Contributed talk
Topological Bogoliubov excitations in inversion-symmetric
systems of interacting bosons
G. Engelhardt∗ , T. Brandes
On top of the mean-field analysis of a Bose-Einstein condensate, one typically applies
the Bogoliubov theory to analyze quantum fluctuations of the excited modes. Therefore,
one has to diagonalize the Bogoliubov Hamiltonian in a symplectic manner. In our article
we investigate the topology of these Bogoliubov excitations in inversion-invariant systems
of interacting bosons. We analyze how the condensate influences the topology of the
Bogoliubov excitations. Analogously to the fermionic case, here we establish a symplectic
extension of the polarization characterizing the topology of the Bogoliubov excitations
and link it to the eigenvalues of the inversion operator at the inversion-invariant momenta.
We also demonstrate an instructive but experimentally feasible example that this quantity
is also related to edge states in the excitation spectrum.
[1] G. Engelhardt and T. Brandes, Phys. Rev. A 91, 053621 (2015).
19
Contributed talk
Homogenization of Cahn–Hilliard equations
Sina Reichelt∗ , Matthias Liero
∗
Weierstrass Institute Berlin
We present a new result [1] on the asymptotic behavior of Cahn–Hilliard equations
with periodically oscillating coefficients. The period ε > 0 describes the characteristic
length scale of the underlying microstructure and we rigorously derive effective equations
for the limit ε → 0. An application, we have in mind, is the dewetting process of thin
films on (micro-) structured substances. Exploiting the gradient structure as well as the
Γ-convergence of the energy and dissipation functionals, we prove that the limit is a Cahn–
Hilliard equation with homogenized coefficients. Depending on the convexity properties
of the potential (quartic function), we distinguish between two different approaches,
namely, variational inequalities versus the energy-dissipation principle.
[1] Matthias Liero and Sina Reichelt, “Homogenization of Cahn-Hilliard-type equations
via evolutionary Γ-convergence”, WIAS Preprint No. 2114 (2015).
20
Contributed talk
Applying equivariant Pyragas control to our SFB logo
Isabelle Schneider1∗ , Matthias Bosewitz2
2
1 Institut für Mathematik, Freie Universität Berlin, 14195 Berlin
Department of Mathematics, The University of Auckland, New Zealand
By extending the well-known Pyragas control scheme to include spatio-temporal patterns, it is now possible to target the different periodic orbits and stabilize them by a
noninvasive control scheme. In this talk, we give an illustrated step-by step instruction on how to apply equivariant Pyragas control to our SFB logo, i.e. to a ring of ten
Stuart-Landau oscillators with two-nearest-neighbor coupling.
21
Invited talk
Virtual space-time delay dynamics and their chimera states
L. Larger1∗ , B. Penkovskyi1 , Y. Maistrenko2
2
1 FEMTO-ST / Optics dept. P.M. Duffieux,
15B Av. des Montboucons, 25030 Besançon cedex, France
Institute of Mathematics and Center for Medical and Biotechnical Research, NAS of
Ukraine, Tereschenkivska Str. 3, 01601 Kyiv, Ukraine
The infinite dimensional phase space of a delay differential equation can be straightforwardly illustrated by noticing that its initial conditions, even in the simplest case of
a scalar dynamical variable x(t) ruled by τ ẋ(t) = −x(t) + fNL [x(t − τD ], is obviously a
functional of time spanning over an interval covering the duration of the delay τD :
{x0 (t) | t ∈ [−τD ; 0]}.
Such a simple model nevertheless offers a potential for complex motions, “a priori”
similar to that of spatio-temporal dynamics, owing to the huge possibilities provided
by the infinite dimensional character. Such a space-time analogy was indeed studied
more then 20 years ago [1], decomposing the multiple time scale feature (τ τD ) into
a discrete variable n ∈ N illustrating an iteration from one time delay interval to the
next, and a continuous virtual space variable σ ∈ [0; τD ] accounting for the necessary
continuous fluctuations of x over small time scales of the order of τ .
Beyond the mathemical curiosity of such a simple equation of motion developing potentially complex solutions, delay equations have the exciting interest in Physics, more
specifically in Optics, to be experiment-friendly, with a high controlability, appearing as
a tool to explore infinite dimension in the time domain only.
Figure 1: Birth of 3- 2- and single-headed chimera in a delayed feedback laser. The color
coding shows the amplitude of the virtual space-time pattern xσ (n).
This talk will try to bridge the theory and the experiment of delay equations in Optics,
through the illustration of a fascinating self-organized motion known as chimera states.
Chimeras were initially discovered [2] in dynamical systems made of space-distributed
coupled identical oscillators. Simple modeling will be presented, supported by the description of a real-world tunable laser delayed feedback experiment [3]. Space-time analogy will be derived from the model, and the conditions for the emergence of chimeras
will be explained. Recent features will be also reported, such as multi-stability domains
in the parameter space where several kinds of multiple headed chimera can coexist. [4].
[1] F.T. Arecchi et al., Phys. Rev. A 45, pp. R4225–R4228 (1992).
[2] Y. Kuramoto and D. Battogtokh, Nonlin. Phenom. Compl. Syst. 5, pp. 380–385
(2002).
[3] J.-P. Goedgebuer et al., Phys. Rev. Lett. 80, pp. 2249–2252 (1998).
[4] L. Larger et al., Nat. Commun. (to appear, July 2015).
22
Contributed talk
Multistability and bifurcations of laser cavity solitons induced by
delayed feedback
D. Puzyrev1∗ , A.G. Vladimirov1 , S.V. Gurevich2 , S. Yanchuk1
1
Weierstrass Institute for Applied Analysis and Stochastics, Berlin
2 Institute for Theoretical Physics, University of Münster
The influence of delayed optical feedback on the dynamics of cavity solitons in a broad
area laser with a saturable absorber is studied. In the absence of the delayed feedback, the
branch of localized solutions winds itself into spiral on the parameter plane [1]. However,
in the presence of the delayed feedback, solution branches fill the surface of the solution
“tube” in the parameter-coordinate space. Furthermore, the “tube” of solutions is filled
densely with increasing delay time.
This phenomenon, described for the CGLE plane wave case in [2], is analogous to the
appearance of the external cavity modes (ECM) observed in the rate equation models
for semiconductor lasers with delayed feedback.
In addition, it was shown that stability properties of solutions strongly depend on the
delayed feedback parameters: total feedback phase and feedback rate. In particular, the
thresholds of the drift and phase instabilities were obtained analytically. Modulational
instability of the soliton was investigated using large delay approximation. It was found
that the wiggling soliton solutions induced by modulational instability emerge for a range
of delayed feedback parameters.
[1] A.G. Vladimirov, N.N. Rozanov, S.V. Fedorov, and G.V. Khodova. Bifurcation
analysis of laser autosolitons. Quantum Electronics, 27(11):949–952, 1997.
[2] D. Puzyrev, S. Yanchuk, A. Vladimirov, and S. Gurevich. Stability of plane wave solutions in complex Ginzburg–Landau equation with delayed feedback. SIAM Journal
on Applied Dynamical Systems, 13(2):986–1009, 2014.
23
Wittenberg 2015
Program schedule – Wednesday
Wednesday, September 16th
Chair: Philipp Hövel
9:00
9:45
Yuliya Kyrychko (University of Sussex, UK) (invited)
Dynamics of neural networks with discrete and distributed time delays
Coffee break
Chair: Nikita Begun
10:15
10:35
10:55
Andreas Koher (Technische Universität Berlin, Germany) (B10)
Temporal networks and applications to epidemiology
Josef Ladenbauer (Technische Universität Berlin, Germany) (B8)
Low-dimensional spike rate dynamics of coupled adaptive model neurons
Coffee break
Chair: Jason Bassett
11:25
11:45
12:05
12:25
Robert Lasarzik(Technische Universität Berlin, Germany) (A8)
Continuum theories for smectic-A liquid crystals
Volker Mehrmann (Technische Universität Berlin, Germany) (A2)
Optimal control of delay differential-algebraic equations
Mark Curran (Freie Universität Berlin, Germany) (A9)
Reaction-diffusion equations with hysteresis in higher spatial dimensions
Lunch
Chair: Pavel Gurevich
14:00
14:45
15:30
Martin Brokate (Technische Universität München) (invited)
Optimal control in evolutions with hysteresis
Closing remarks
Departure
25
Invited talk
Dynamics of neural networks with discrete and distributed time
delays
Yuliya Kyrychko∗ , Bootan Rahman, Konstantin Blyuss
Department of Mathematics, University of Sussex, Falmer, Brighton, BN1 9QH, United
Kingdom
In this talk I will present a Hopfield-type neural network model, where one sub-system
receives a delayed input from another sub-system. The model includes a combination of
both discrete and distributed delays, where distributed time delays represent the neural
feedback between the two sub-systems, and discrete delays describe the neural interactions within each of the two sub-systems. Stability properties are investigated for different
commonly used distribution kernels, and the results are compared to the corresponding
results on stability analysis for networks with no distributed delays. I will show how
boundaries of the stability region of the trivial equilibrium can be obtained analytically
for the cases of delta, uniform and gamma distributions. Direct numerical simulations
that confirm analytical findings will also be presented.
26
Contributed talk
Temporal Networks and applications to epidemiology
A. Koher∗ , V. Belik, T. Isele, J. Bassett, F. Herrmann, A. Fengler, P. Hövel
Technische Universität Berlin, Hardenbergstr. 36, 10623 Berlin
Network science has developed into a prominent tool, which helps to predict the dynamics of infectious diseases and thereby already led to effective containment and vaccination
strategies [1]. However, if the dynamics is dominated by the time-dependent features of
the network, the classical, static approaches need to be replaced by a description that
incorporates the evolving graph [2].
In this talk we will give an overview of our recent results that connect the (temporal)
network approach with applications to epidemiology. In particular, we focus on the
German animal trade network, which is considered to be an important pathway for
animal-related diseases. We will characterize the graph in terms of static and temporal
features, such as static components and centrality measures in order to propose targeted
vaccination strategies. Furthermore, we will introduce the concept of temporal paths and
use a Boolean matrix formalism to calculate the resulting reachabilty graph. This kind
of network contains a directed edge only if there exists a temporal path between two
nodes in the underlying graph. The algebraic formalism will then be used to evaluate
the vulnerability and reachability of single nodes and to calculate the giant strongly
connected component in the temporal network [3] as a rough estimate for the potential
outbreak size.
Recently, a nonlinear edge-weight transformation has been proposed in order to analyse
the most probable paths in an epidemic outbreak [4]. The idea has been successfully
applied to forecast and track-back human-related diseases, which are mainly transmitted
through the air-transport network on a global scale. Following this promising approach
we will present preliminary results for the German animal trade network and suggest
generalizations to the case of time evolving graphs in the second part of the talk.
Finally, we will evaluate a control mechanism to contain potential epidemic outbreaks
by rearranging the temporal links. This will isolate infected nodes after a certain detection
time and therefore effectively reduce the infectious period. A singular feature of the
animal trade network is given by a functional property, which attaches an attribute to
each node such as piglet production, raising, fattening, slaughtering and trading. In order
to respect this particularity we will give a short overview on techniques, which assess the
role of a node within a network.
[1] L. Danon, A. P. Ford, T. House, C. P. Jewell, M. J. Keeling, G. O. Roberts, J. V.
Ross, and M. C. Vernon. Networks and the epidemiology of infectious disease. Interdisciplinary Perspectives on Infectious Diseases, 2011:1, 2011.
[2] Vincenzo Nicosia, J Tang, Cecilia Mascolo, Mirco Musolesi, Giovanni Russo, and Vito
Latora. Graph metrics for temporal networks. In Petter Holme and Jari Saramäki,
editors, Temporal Networks, Understanding Complex Systems. Springer Berlin Heidelberg, 2013.
[3] Vincenzo Nicosia, J Tang, Mirco Musolesi, Giovanni Russo, Cecilia Mascolo, and Vito
Latora. Components in time-varying graphs. Chaos, 22:023101, 2012.
[4] D. Brockmann and Dirk Helbing. The hidden geometry of complex, network-driven
contagion phenomena. Science, 342:1337–1342, 2013.
27
Contributed talk
Low-dimensional spike rate dynamics of coupled adaptive model
neurons
J. Ladenbauer1,2∗ , M. Augustin1,2 , K. Obermayer1,2
1
Neural Information Processing Group, Technische Universität Berlin
2 Bernstein Center for Computational Neuroscience Berlin
How the properties of single neurons and their coupling give rise to different types
of functionally relevant collective dynamics can be effectively studied using population
activity models derived from calibrated model neurons. The activity of single neurons is
well described by an integrate-and-fire model that take into account neuronal adaptation.
Considering a large population of these model neurons, exposed to fluctuating inputs
and sparsely coupled, the collective spike rate dynamics can be characterized by a lowdimensional ordinary differential equation derived in a mean-field limit using the FokkerPlanck equation. This reduced description is computationally very efficient, directly links
single neuron properties and network dynamics, and allows for convenient mathematical
analyses of biologically relevant rhythmic and asynchronous network states. It is therefore
well suited for the application in mean-field (neural mass) based brain network models.
A model extension that reflects the stochastic dynamics of finite populations (finite-size
effects/noise-induced phenomena) and methods for networks of neuronal networks will
be outlined.
28
Contributed talk
Continuum theories for smectic-A liquid crystals
Robert Lasarzik∗ , Etienne Emmrich
Institut für Mathematik, Technische Universität Berlin, Straße des 17. Juni 136, 10623
Berlin, Deutschland,
Liquid crystals are materials consisting of rod-like molecules that form complex configurations. Depending on the structure, these materials exhibit multifaceted properties
giving rise to multiple applications, such as displays in electronic devices or optical imaging in medicine. The smectic-A phase is characterised by molecules distributed in layers,
in which all molecules are aligned in the direction of the layer normal.
In this talk, we discuss different modelling strategies for smectic-A liquid crystals. A
theory is presented that incorporates possible undulation phenomena, which arise due to
dilatation of the layers. We survey the mathematical theory for such models and give a
new existence result.
29
Contributed talk
Optimal control of delay differential-algebraic equations
P. Kunkel1 , V. Mehrmann2∗
1 Universität Leipzig
Technische Universität Berlin
2
∗
We discuss the solution of optimal control problems with linear delay differential-algebraic
equation (DDAE) constraints. Compared to the already complicated case of standard
differential-algebraic equation (DAE) constraints, several further difficulties arise.
These include the decreased regularity in the solution and the occurrence of higher
derivatives of the input functions. We present the necessary optimality conditions under
the assumption that the method of steps leads to a reasonable solution and discuss the
algebraic properties of the optimality system.
30
Contributed talk
Reaction-Diffusion Equations with Hysteresis in Higher Spatial
Dimensions
Mark Curran∗
∗
Free University of Berlin, SFB 910
In this talk, we will treat the equation
ut = ∆u + f (u, H(u)),
(1)
where u represents a diffusing substance and H(u) is a hysteresis operator defined at every
spatial point. Such equations model processes where the non-diffusing substance H(u)
can be in one of two states, and the switching mechanism between states is determined
by a hysteresis law. These equations model a variety of biological and chemical processes
that exhibit spatial-temporal patterns [1, 2, 3].
Numerical simulations of such models are in agreement with experiment, however questions of the existence and uniqueness of solutions, as well a rigorous explanation of the
mechanisms for pattern formation remain open.
The set of points where H(u) is in one state or the other naturally segregates the domain
into two subdomains. Moreover, a switching mechanism implies that these subdomains
are separated by free boundaries.
I will present conditions on the free boundary and initial data that guarantee the
existence and uniqueness of solutions of (1).
[1] F. Hoppensteadt and W. Jäger. Pattern Formation by Bacteria. In Biological Growth
and Spread, volume 38 of Lecture Notes in Biomathematics (W. Jäger, H. Rost, and
P. Tautu, editors,), pages 68–81. Springer Berlin Heidelberg, 1980.
[2] F. Hoppensteadt, W. Jäger, and C. Pöppe. A hysteresis model for bacterial growth
patterns. In Modelling of Patterns in Space and Time, volume 55 of Lecture Notes
in Biomathematics (W. Jäger and J. D. Murray, editors,) , pages 123-134. Springer
Berlin Heidelberg, 1984.
[3] A. Marciniak-Czochra. Receptor-based models with hysteresis for pattern formation
in hydra. Mathematical Biosciences, 199(1):97–119, 2006.
31
Invited talk
Optimal Control in Evolutions with Hysteresis
Martin Brokate∗
Fakultä für Mathematik M6, TU München, 85747 Garching, Germany
We consider evolutions which arise from a coupling of a differential equation (ordinary
or parabolic) with a rate independent element, the latter being described by a hysteresis operator or a variational inequality. Such evolutions are inherently nonsmooth. We
present results from several collaborations including the author obtained in recent years.
Topics discussed are generalized differentiability properties of the rate independent elements and of the control-to-state mapping, regularization approaches as well as optimality
conditions.
32
Wittenberg 2015
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
Poster session
Posters
Jason Bassett (Technische Universität Berlin, Germany) (B10)
A comparative study of the deterministic and stochastic approach of the
population dynamics model SIRS
Fabian Baumann (Technische Universität Berlin, Germany) (B8)
Low-dimensional models for the population dynamics of adaptive
integrate-and-fire neurons
Nikita Begun (Freie Universität Berlin, Germany) (A9)
Stability of hyperbolic attractors
Konstantin Blyuss (University of Sussex, UK)
Time-delayed model of immune response in plants
Fabian Böhm (Technische Universität Berlin, Germany) (B9)
Exploiting multi-stability to achieve chimera states in all-to-all coupled laser
networks
André Eikmeier (Technische Universität Berlin, Germany) (A8)
Nonmonotone stress-strain relations
Sascha Gerloff (Technische Universität Berlin, Germany) (B2)
Shear-induced non-equilibrium transititions in colloidal films by feedback control
Sven Moritz Hein (Technische Universität Berlin, Germany) (B1)
Time-delayed quantum-coherent feedback control: pseudomode approach and
application to photon statistics
Wassilij Kopylov (Technische Universität Berlin, Germany) (A7)
Two-mode Tavis-Cummings model with time-delayed feedback control
Nicolas Naumann (Technische Universität Berlin, Germany) (B1)
Optical control of solid state systems
Felix Rühle (Technische Universität Berlin, Germany) (B4)
Hard and soft particles in inertial microfluidics
Jakub Sawicki (Technische Universität Berlin, Germany) (A1)
Synchronization of organ pipes
Igor Shepelev (Saratov State University, Russia) (B11)
Dynamical chimeras in a ring of oscillators with local coupling
Benjamin Unger (Technische Universität Berlin, Germany) (A2)
Regularization of delay differential-algebraic equations and their input/output
realization
Nicola Vassena (Freie Universität Berlin, Germany) (A4)
Monomolecular reaction networks: a new proof of flux transitivity
Matthias Wolfrum (WeierstraßInstitut Berlin, Germany) (A3)
Chimera states with global feedback
Alexander Ziepke (Technische Universität Berlin, Germany) (B6)
Front propagation in sinusoidally modulated channels and tubes
33
Poster
A Comparative Study of the Deterministic and Stochastic
Approach of the Population Dynamics Model SIRS
J. Bassett1∗ , A. Provata2†
2
1 Technische Universität Berlin, Institute for Theoretical Physics
National Center for Scientific Research “Demokritos”, Institute for Nanoscience and
Nanotechnology
† Electronic Address: [email protected]
Deterministic and stochastic models are often used in population dynamics to analyse
epidemic evolution in spatially distributed populations. In this presentation, the time
evolution of epidemics is generated by the non-linear epidemic SIRS model, in which
the total population is divided in subgroups, which interact either deterministically or
stochastically. These groups are S, I and R with the three symbols referring to population
units, which are identified as Susceptible, Infected and Recovered respectively. For the
deterministic part, a dynamical analysis is performed within the scope of Mean Field
theory. In particular, local stability analysis, vector field, bifurcation analysis, and numerical integration of the system are employed [1]. The threshold for an outbreak is also
defined [2]. In the stochastic part, the Kinetic Monte Carlo (KMC) method is employed
in one dimension to simulate the evolution of the S, I and R local concentrations as individuals (rather than groups/compartments) interact. In the KMC realisations single cell
occupation is assumed by individuals characterised as S, I or R, much as in the approach
of the Ising model. The KMC method is shown to introduce finite size effects, spatial
dependence for the population evolution, poisoning states and nontrivial dependence on
initial conditions, effects which are not predicted by the Mean Field approach. These
effects are attributed to the spatial extension of the system which is taken into account
by the KMC method, while it is ignored in the Mean Field approach [3].
[1] Aadil Lahrouz, Lahcen Omari, Driss Kiouach, Aziza Belmaâti, Complete global
stability for an SIRS epidemic model with generalized non-linear incidence and vaccination, Applied Mathematics and Computation 218, 65196525, 2012.
[2] Shujing Gao and Yujiang Liu and Juan J. Nieto and Helena Andrade, Seasonality
and mixed vaccination strategy in an epidemic model with vertical transmission,
Mathematics and Computers in Simulation 81, 18551868, 2011.
[3] Ganna Rozhnova and Ana Nunes, Stochastic effects in a seasonally forced epidemic
model, Phys. Rev. E 82, 041906, 2010.
34
Poster
Low-dimensional models for the population dynamics of adaptive
integrate-and-fire neurons
M. Augustin1,2∗ , J. Ladenbauer1,2† , F. Baumann1 , K. Obermayer1,2
1
Neural Information Processing Group, Technische Universität Berlin
2 Bernstein Center for Computational Neuroscience Berlin
† Electronic Address: [email protected]
The spiking activity of single neurons can be well described by a two-dimensional
integrate-and-fire model that includes neuronal adaptation caused by slowly decaying
potassium currents. For fluctuating inputs sparsely coupled spiking model neurons exhibit stochastic population dynamics which can be effectively characterized using the
Fokker-Planck equation. This approach leads to a model with an infinite-dimensional
state space and non-standard boundary conditions. However, the spike rate dynamics can be approximated by a low-dimensional ordinary differential equation in different
ways. Here, we first extend these approximation techniques to account for neuronal
adaptation and then evaluate the reduced models in terms of spike rate reproduction
accuracy for a range of biologically plausible input statistics, computational demand and
implementation complexity. These reduced descriptions are well suited for (i) application
in neural mass/mean-field based brain network models, having a link to single neuron
properties retained and being computationally efficient, and (ii) mathematical analyses
of, for example, rhythmic and asynchronous network states.
35
Poster
Stability of hyperbolic attractors
Nikita Begun∗
Freie Universität Berlin, Institut für Mathematik
The dynamical object which we study is a compact invariant set with a suitable hyperbolic structure. Stability of hyperbolic attractors was studied by V. A. Pliss and G.
R. Sell. They assumed that the neutral and the stable linear spaces of the corresponding linearized systems satisfy Lipschitz condition. They showed that if a perturbation is
small, then the perturbed system has a hyperbolic attractor K Y , which is homeomorphic
to the hyperbolic attractor K of the initial system, close to K, and the dynamics on K Y
is close to the dynamics on K. At the same time, it is known that the Lipschitz property
is too strong in the sense that the set of systems without this property is generic. Hence,
there was a need to introduce new methods of studying stability of hyperbolic attractors
without Lipschitz condition. We will show that even without Lipschitz condition there
exists a continuous mapping h such that h(K) = K Y .
36
Poster
Time-delayed model of immune response in plants
K.B. Blyuss∗ , G. Neofytou, Y.N. Kyrychko
Department of Mathematics, University of Sussex, Falmer, Brighton, BN1 9QH, United
Kingdom
In the studies of plant infections, an important role is known to be played by the plant
immune response. In this work we derive and analyse a new mathematical model of plant
immune response with particular emphasis on the effects of post-transcriptional gene
silencing (PTGS). Besides biologically accurate representation of the PTGS dynamics,
the model explicitly includes two time delays to represent the maturation time of the
growing plant tissue and the non-instantaneous nature of the PTGS. Different biologically
realistic steady states are identified, and their stability is studied both analytically and
numerically. This allows us to identify parameter regions associated with recovery and
resistant phenotypes, as well as possible chronic infections, in terms of system parameters
and the time delays. Different types of dynamical behaviour of the system are illustrated
by numerical simulations of the model.
37
Poster
Exploiting multi-stability to achieve chimera states in all-to-all
coupled laser networks
F. Böhm1∗ , K. Lüdge2
1
Institut f. Theo. Physik, Sekr. EW 7-1, Technische Universität Berlin, Hardenbergstr.
36, 10623 Berlin, Germany
2 Institut f. Theo. Physik, Freie Universität Berlin, Arnimallee 14, 14195 Berlin,
Germany
Advancements in fabrication techniques of photonic circuits allow for the realization of
large networks of optically coupled semiconductor lasers as on-chip solutions. These small
devices are promising for the study of complex network dynamics and new methods in
signal processing. Our work focuses on arrays of identical semiconductor lasers where the
individual units are globally coupled by a common mirror in a short external cavity. Using
the Lang-Kobayashi model for the local laser dynamics, we investigate the bifurcation
structure in regards to multistabilities and the occurring rich variety of dynamics . We
identify the material parameters of the lasers, e.g. the amplitude-phase-coupling and the
time scale seperation between electrons and photons as driving forces for multi-stability
and complex synchronization phenomena. We show that regions of multistablity between
the synchronous steady state and asynchronous periodic solutions allow for the formation
of tiny chimera states. The domains of coherence and incoherence that are typical for
chimera states are found to exist simultaneously for the amplitude, phase, and inversion
of the coupled lasers. These tiny chimera states are interesting in regards to established
existence criteria. While chimera states in phase oscillators generally demand nonlocal
coupling, large system sizes, and specially prepared initial conditions, we find chimera
states that are stable for global coupling in a network of only four coupled lasers for
random initial conditions.
[1] F. Böhm, A. Zakharova, E. Schöll, K. Lüdge, Phys. Rev. E 91(4), 040901 (R) (2015)
38
Poster
Nonmonotone stress-strain relations
A. Eikmeier∗
Institut für Mathematik, Technische Universität Berlin, Straße des 17. Juni 136, 10623
Berlin, Germany
Nonmonotone stress-strain relations typically appear in modelling materials under
phase transitions. In the example of a shear-induced isotropic-nematic transition in
liquid crystals (Fig. 1), the stress σxy is nonmonotone in the shear rate Γ.
Proving the existence of solutions to such problems is quite challenging since the lack
of monotonicity prevents us from applying the famous “Minty-Trick” to show that the
limit of solutions to the approximate problems is indeed a solution of the actual problem.
Therefore, we only expect existence of measure-valued solutions instead of weak solutions.
The problem considered in [1] motivates studying a simplified equation, the so-called
backward-forward heat equation
∂u
− ∇ · q(∇u) = 0, x ∈ Ω, t > 0,
∂t
(1)
where q : Rn → Rn is a nonmonotone function. Even though the physical interpretation
of (1) is different since q is not representing the stress, it is mathematically interesting
to investigate because q also generates a nonmonotone operator.
In this poster, we survey results proving the existence of measure-valued solutions to
(1), such as given in [2, 3].
Figure 1: Shear-induced isotropic-nematic transition [1]
[1] S. H. L. Klapp, S. Hess, Shear-stress-controlled dynamics of nematic complex fluids,
Phys. Rev. E, 81 (2010) 051711.
[2] M. Slemrod, Dynamics of measure valued solutions to a backward-forward heat equation, J. Dyn. Differ. Equations, 3 (1991) 1, pp. 1-28.
[3] K. Höllig, J. A. Nohel, A diffusion equation with a nonmonotone constitutive function, Systems of Nonlinear Partial Differential Equations, ed. J. M. Ball, Reidel,
Dordrecht, 1983, pp. 409-422.
39
Poster
Shear-induced non-equilibrium transititions in colloidal films by
feedback control
Sascha Gerloff∗ , Tarlan A. Vezirov, Sabine H. L. Klapp
Colloidal particles under the combined in influence of an external driving force and restricted geometry exhibit a wealth of non-linear phenomena, which are relevant in diverse
fields such as directed particle transport, sorting mechanisms and friction phenomena at
the nanoscale.
Using Brownian dynamic simulations, we investigate non-equilibrium transitions of a
thin film of charged colloids in planar shear flow. The particles interact via a combined
screened Coulomb and softsphere potential with parameters suited to model ludox-silica
particles. By confining the colloids to a narrow slit-pore, the formation of colloidal crystal
layers is induced and the colloids are driven by a planar shear flow, leading to complex
non-linear dynamics.
Considering a bilayer system, we observed several steady states characterized by pinning,
shear-induced melting and reentrant ordering into a moving hexagonal state with synchronised oscillations of the particles [1]. Here, we introduce a global feedback control
scheme, allowing to switch between the pinned and hexagonal state [2]. In our approach
the shear rate becomes a dynamical variable, which relaxes on a timescale (τc ) such that
the instantaneous, configuration-dependent shear stress approaches a pre-imposed value.
Indeed, the final state strongly depends on τc relative to an intrinsic relaxation time of
the uncontrolled system and the critical values of τc are estimated on the basis of a simple
model. Additionally, the introduced feedback control scheme is not limited to the bilayer
system and was successfully applied to the trilayer system, for an appropriate choice of
the target shear stress and control timescale τc .
Moreover, investigating the trilayer system reveals a novel steady state, which is characterized by the separation of the middle layer into two sublayers. We show that the
separated sublayers move in opposite directions, therefore deviating from the imposed
linear velocity profile. Furthermore, the dynamics are enabled by the formation of lanes.
The shear-induced order transition displays a strong impact not only on the structure of
the system but also its rheology.
[1] T. A. Vezirov and S. H. L. Klapp, Phys. Rev. 88, 052307 (2013)
[2] T. A. Vezirov, S. Gerloff and S. H. L. Klapp, Soft Matter 11, 406-413 (2015)
40
Poster
Time-delayed quantum-coherent feedback control: Pseudomode
approach and application to photon statistics
Sven Moritz Hein∗ , Manuel Kraft, Franz Schulze, Alexander Carmele, Andreas Knorr
Technische Universität Berlin, Institut für Theoretische Physik, Hardenbergstraße 36,
10623 Berlin
We present a novel method to tackle the numerical challenges of Pyragas-type timedelayed feedback in quantum optics that arise due to the presence of multiple time scales.
In the usual approach [1, 2, 3], Pyragas-type control is implemented by coupling the
system to a “structured” reservoir using a frequency-dependent coupling constant γ(ω) =
sin(ωL/c), which however requires a very high resolution in frequency space.
We demonstrate that feedback can be modeled effectively by replacing the structured
reservoir by a small (∼ 30) number of damped harmonic oscillators. Using differential
equations for expectation values rather than solving the Schrödinger equation directly
allows to include incoherent processes such as scattering or pumping events. Furthermore,
this approach also points towards a representation of coherent self-sustained time-delayed
feedback in terms of a network without an explicit external feedback loop.
Additionally, we present applications of time-delayed quantum-coherent feedback in
the area of quantum optics. We show how entanglement between nodes in a quantum
network, as well as between photons [4], can be created, enhanced, and controlled. We
also show strong effects of time-delayed quantum-coherent feedback on nonlinear optical
systems, such as a cavity containing a quantum dot or a Kerr medium (χ(3) nonlinearity).
In particular, the number of excitations within such a system strongly depends on the
delay time of the applied feedback loop.
[1] U. Dorner and P. Zoller, Phys. Rev. A 66, 023816 (2002)
[2] A. Carmele et al., Phys. Rev. Lett. 110, 013601 (2013)
[3] F. Schulze et al., Phys. Rev. A 89, 041801 (2014)
[4] S. M. Hein et al., Phys. Rev. Lett. 113, 027401 (2014)
41
Poster
Two-Mode Tavis-Cummings Model with Time-Delayed Feedback
Control
W. Kopylov1∗ , M. Radonjić2 , T. Brandes1 , A. Balaž3 , A. Pelster4
1
Institut für Theoretische Physik, Technische Universität Berlin, D-10623 Berlin,
Germany
2 Photonics Center, Institute of Physics Belgrade, University of Belgrade, Serbia
3 Scientific Computing Laboratory, Institute of Physics Belgrade, University of
Belgrade, Serbia
4 Physics Department and Research Center OPTIMAS, Technische Universität
Kaiserslautern, Germany
We investigate a two-mode laser system by extending the two-mode Tavis-Cummings
model with dissipative channels and incoherent pumping in the thermodynamic limit. To
this end we analytically determine up to four possible non-equilibrium steady states (fixed
points) and show the corresponding complex phase diagram. Various possible phases are
distinguished by the actual number of fixed points and their stability. In addition, we
apply three time delayed Pyragas feedback control schemes. Depending on the time delay
and the strength of the control term this can lead to the stabilization of unstable fixed
points or to the selection of a lasing mode that is macroscopically occupied
42
Poster
Optical control of solid state systems
N.L. Naumann1∗ , J. Kabuß1 , A. Carmele1 , L. Droenner1 , W.W. Chow2 , A. Knorr1
1
Nichtlineare Optik und Quantenelektronik, Institut für Theoretische Physik,
Technische Universität Berlin, Hardenbergstr. 36, 10623 Berlin, Germany
2 Sandia National Laboratories, Albuquerque, New Mexico 87185-1086, USA
The properties of nanostructures such as semiconductor quantum dots (QDs) can be
tailored to particular needs due to advanced fabrication techniques. To make use of these
structures for applications, their dynamics and statistics need to be controlled [1]. In our
investigations, we employ optical control schemes. For instance, an external control laser
can be used to influence the dynamics of the system. Furthermore, the system can be
controlled by feeding back a part of its own dynamics. Optical feedback can be achieved
by reflecting the light field using a mirror. The presented work is composed of two major
parts.
In the first part, we explore systems, which can sustain coherent phonons, as needed
for building phonon lasers. Here, we compare two cases. The first one is the standard
optomechanical setup [2] is considered, where a single photon mode is interacts with
the mechanical mode of a micromechanical osillator via radiation pressure. The second
one is a solid state system, where one or several QDs are coupled to a single phonon
mode. We focus on three effects, which are present in both cases and compare their
characteristics in each case. The similarity of both systems can be demonstrated by
considering the bistability as a stationary property. In the limit of a large number of QDs,
the systems semiconductor system approaches the optomechanical one. Furthermore, we
consider two related effects. By pumping the system with a detuning, which matches
the phonon frequency, the creation of phonons can either be suppressed, or enhanced.
The enhancement of phonons is realized with a blue shifted pump laser and realizes the
creation of coherent phonons in both systems. By increasing the number of QDs, we can
amplify the effects, again approaching the optomechanical system.
For the case with one QD the creation of coherent phonons in the blue detuned regime
was already investigated [3] in the quantum limit. In our current work, we expand the
quantum mechanical description to a number of N QDs. In the second part, methods for
treating optical feedback in the quantum limit are investigated. The feedback can then be
used to control the dynamics of a system intrinsically, which was first proposed in classical
systems [4]. It is included via the coupling to a structured mode continuum and results in
a characteristic parameter, the feedback time τ . Thus, an analytical approach for dealing
with these modes is developed for the Jaynes-Cummings model subject to feedback [5].
Furthermore, a numerical scheme for treating the feedback modes is developed, since
more complex systems are often inaccessible for an analytical treatment. To do this, an
operator based method is being developed resulting in equations, which are valid for each
time interval τ .
[1] J. Kabuß, el at., Phys. Status Solidi B, 248, 872 (2011)
[2] N. Naumann, et al., Phys. Rev. A, 90, 043835 (2014)
[3] J. Kabuß, et al., Phys. Rev. Lett., 109, 054301 (2012)
[4] K. Pyragas, Pys. Lett. A, 170, 421 (1992)
[5] J. Kabuß, et al., arXiv:1503.05722 [quant-ph] (2015)
43
Poster
Hard and soft particles in inertial microfluidics
Felix Rühle∗ , Christopher Prohm, Holger Stark
TU Berlin, Institut für Theoretische Physik, Hardenbergstr. 36, 10623 Germany
We investigate hard and soft particles in rectangular microchannels under the influence of Poiseuille flow at intermediate Reynolds numbers. It is well known that a single
particle shows inertial focussing in this regime [1]. Furthermore, for rectangular channels with sufficiently large aspect ratio only two lateral equilibrium positions exist. In
this contribution we present different aspects of this setting using Lattice-Boltzmann
simulations.
First, we place a pillar in the microchannel [2] and study how it influences the particle
position after passing the pillar. We find that the particle displacement induced by the
pillar is largely outweighed by the cross-streamline migration due to the inertial fluid
flow.
Second, we place a pair of rigid particles close to their equilibrium lateral positions with
varying distance and monitor their relaxation towards the steady state. Our preliminary
results suggest three types of trajectories and that the final particle distance depends on
the inital distance. An in-depth understanding of these trajectories will provide insights
into the properties and dynamics of particle chains as well as the formation of so-called
microfluidic crystals [3].
Third, we make the particles soft and present first results how they move closer to the
center line with increasing softness and ultimately reside on the center line. Deformability
is a key property of biological cells. We are mainly interested in red blood cells, which we
model as a fluid-filled capsule according to [4]. In addition, cancer cells are softer than
conventional cells and our findings may be used to identify them.
[1] G. Segré and A. Silberberg, Nature 189, 209 (1961).
[2] H. Amini et al., Nat. Comm. 4, 1826 (2013).
[3] W. Lee et al., PNAS 107, 22413 (2010).
[4] T. Krüger, F. Varnik and D. Raabe, Comput. Math. Appl. 61, 3485 (2011).
44
Poster
Synchronization of Organ Pipes
Natalia Spitha1∗ , Jakub Sawicki1 , Anna Zakharova1 , Markus Abel2 , Eckehard Schöll1
1
Institut für Theoretische Physik, Technische Universität Berlin
2 Institut für Physik und Astronomie, Universität Potsdam
The synchronization of organ pipes has become a truly interdisciplinary topic in recent
years, driven by theoretical approaches to synchronization [2], computational aeroacoustics [4], and musical acoustics [1, 3].
One important theoretical question is the transition to synchronization, most often
characterized in the parameter plane of coupling strength and frequency detuning. The
synchronization region in this plane is generally called Arnold tongue, and is one of the
main characteristics of synchronizing nonlinear systems.
For organ pipes, there are a few relevant scenarios where synchronization enters into
the game: If pipes are put close to each other in the prospect, the pipes may weaken the
sound emitted, because they synchronize in anti-phase. Reflecting walls may play a role,
when the signal is fed back onto itself. The transition of organ pipes to synchronization
has been studied for a model of two coupled van der Pol oscillators [5], where a constant
coupling was used. Consequently, in this project, we aim at the detailed study the
behavior of the Arnold tongue for a more complex coupling model. We consider two
coupled van der Pol oscillators, which have been established as an effective description
for organ pipes:
ẍi (t) + ωi2 xi (t) − µ 1 − γxi (t)2 x˙i (t) = C(τ )ẋj (t − τ ), i, j = 1, 2
(1)
1
where ωi are the eigenfrequencies, C(τ ) = κ
+ κτ2 is the coupling strength, which
τ2
depends on the delay time τ . κi are two coupling factors. The coupling is delayed,
because the sound travels a certain distance d between the pipes. The coupling strength
depends on that distance, since the sound wave is attenuated according to the radiation
of a spherical wave emitted from the pipe mouth. Within the coupling strength C(τ ) we
have a near field term (∝ τ12 ) and a far field term (∝ τ1 ).
[1] M. Abel, S. Bergweiler and R. Gerhard-Multhaupt. Synchronization of organ pipes:
experimental observations and modeling. J. Acoust. Soc. Am. 119, 2467–2475
(2006).
[2] M. Abel, K. Ahnert and S. Bergweiler. Synchronization of Sound Sources. Phys.
Rev. Lett. 103, 114301 (2009).
[3] R. Bader. Nonlinearities and Synchronization in Musical Acoustics and Music Psychology. (Springer, 2013).
[4] J. Fischer. PhD thesis, Universität Potsdam, 2014.
[5] J. Sawicki. Synchronization of Organ Pipes. Master’s thesis, Technische Universität
Berlin, 2014.
45
Poster
Dynamical chimeras in a ring of oscillators with local coupling
I.A. Shepelev∗ , T.E. Vadivasova, V.V. Semenov
Saratov State University, Saratov, Russia
∗ Electronic Address: igor [email protected]
Chimera states in oscillatory ensembles attract the great interest today [1,2]. The
nonlocal character of connections of ensemble elements is one of the typical features of
chimera state. Beside of chimeras in oscillatory ensembles, so called virtual chimera
can exist in a single system with time delayed feedback [3]. It is known that a system
with delayed feedback is similar to a spatially distributed system with periodic boundary
conditions. Using this analogy one can obtain the chimera state in a ring of oscillators
with local unidirectional connections between the elements. Their properties should be
similar to chimera properties in a system with delayed feedback.
In this work we construct the chimera state similar to the virtual chimera in a ring of
oscillators with the local unidirectional nonlinear coupling described in [3]. In addition
we study the chimera regimes in a ring of Duffing oscillators with the local unidirectional
coupling. The stable chimera-like regimes can be observed in this case if some asymmetry
is introduced in the unit of the ring. For example, it can be an asymmetrical friction.
The ring in this case is described as follows:

dxn


= yn ,

dt


 dyn = −αyn − x3n + G(xn ) + k(xn − xn−1 ),
dt
(
β1 xn , xn < 0,
G(xn ) =
β2 xn , xn ≥ 0.
The chimera-like structures evolution is studied with the coupling strength variation for
different numbers of the ring units. The noise influence on chimeras has been also considered.
The study was partially supported by RFBR (research project No.
14-52-12002).
[1] Y. Kuramoto, D. Battogtokh, Nonlinear Phenom. Complex Syst. 5, 380 (2002).
[2] M.J. Panaggio, D.M. Abrams, Nonlinearity 28(3), R67 (2005).
[3] L. Larger, B. Penkovsky, and Y. Maistrenko, Phys. Rev. Lett. 111, 054103 (2013).
46
Poster
Regularization of delay differential-algebraic equations and their
input/output realization
P. Schulze, B. Unger∗
∗
Technische Universität Berlin
Simulation of complex physical, chemical or biological processes described by mathematical models is a standard tool in research and industry. Besides the computational cost
for solving high fidelity models, it might even be challenging to develop the underlying
dynamical system due to its complex nature. Data-driven model order reduction is a
promising approach to construct low-dimensional models directly from measurements.
The rate of change of realistic models often depends not only on the current time point,
but also on the configuration at previous time instances and we wish to preserve this
delay structure in the reduced model.
In this poster, we present a data-driven realization methodology for descriptor systems
with retarded argument and unknown delay, which is a generalization of the Loewner
framework [1]. The realization of the form
E ẋ(t) = A1 x(t) + A2 x(tτ ) + Bu(t),
y(t) = Cx(t)
(1a)
(1b)
is obtained with low computational cost directly from measured input/output data. The
internal delay time is estimated by solving a least-square optimization over some sample
data. Numerical examples outline the effectiveness of the approach.
The state equation (1a) belongs to the more general class of linear time-varying delay
differential-algebraic equations (DDAEs) given by
E(t)ẋ(t) = A1 (t)x(t) + A2 (t)x(t − τ ) + f (t),
(2)
which are essentially ill-posed in general and hence require a suitable regularization prior
to the numerical treatment. We present a novel regularization methodology for the
DDAE (2), which is a generalization of the strangeness-free reformulation procedure [3]
to DDAEs and allows for an efficient computation of the strangeness and shift index
[4]. The resulting regularized system is well-posed and suitable for classical numerical
algorithms.
[1] A. J. Mayo and A. C. Antoulas. A framework for the solution of the generalized
realization problem. Linear Algebra Appl., 425(2-3):634-662, 2007.
[2] V. Mehrmann. Index concepts for differential-algebraic equations. Preprint 03-2012,
Institut für Mathematik, TU Berlin, Str. des 17. Juni 136, D-10623 Berlin, FRG,
2012.
[3] P. Kunkel and V. Mehrmann. Differential-Algebraic Equations. Analysis and Numerical Solution. European Mathematical Society, 2006.
[4] P. Ha and V. Mehrmann. Analysis and Numerical Solution of Linear Delay
Differential-Algebraic Equations. Preprint 42-2014, Institut für Mathematik, TU
Berlin, Str. des 17. Juni 136, D-10623 Berlin, FRG, 2014.
47
Poster
Monomolecular Reaction Networks: a new proof of flux
transitivity
Nicola Vassena∗
Institute of Mathematics - Free University of Berlin - Germany
We study the network response to perturbations of a reaction rate j*. Specifically, we
describe which other reaction rates j respond by nonzero reaction flux, at steady state.
Nonzero responses of j to j* are called flux influence of j* on j. Mochizuki and Fiedler
established transitivity of flux influence, for monomolecular reaction networks. We give
a new, independent, and conceptually simplified proof of that intriguing fact. Our proof
uses standard connectivity concepts from graph theory, and Mengers Theorem. Based
on the network structure, only, this also leads to a simplified characterization of all flux
influence sets.
[1] A. Mochizuki and B. Fiedler, Sensitivity of chemical reaction networks: a structural
approach. 1. Examples and the carbon metabolic network, J Theor Biol. 2015 Feb
21;367:189-202
[2] B. Fiedler and A. Mochizuki, Sensitivity of chemical reaction networks: a structural
approach. 2. Regular monomolecular systems, Math. Meth. Appl. Sci. 2015.
48
Poster
Chimera states with global feedback
M. Wolfrum∗ , O. Omel’chenko
Weierstraß-Institut für Angewandte Analysis und Stochastik, Berlin
We present some recent results on chimera states in systems with global feedback. We
show how to stablize chimera states close to complete coherence and those with small
numbers of oscillators. For small numbers of oscillators we can identify the emergence
of chimera states as a result of transitions to chaos via period doubling cascades, torus
breakup and intermittency.
49
Poster
Front Propagation in Sinusoidally Modulated Channels and
Tubes
A. Ziepke∗ , S. Martens, and H. Engel
Institut für Theoretische Physik, Technische Universität Berlin, Germany
Propagation of traveling fronts in channels and tubes with periodically modulated
cross-section Q(x) is investigated. In the fashion of our recent paper [1], we apply asymptotic analysis for a small changing rate of the channel’s and tube’s cross-sections to reduce
the dimensionality of the problem. Within this approach, the Neumann boundary condition translates into a boundary-induced advection term. Treating the latter as a weak
perturbation, we derive an equation of motion for the front position [2]. In particular,
we study numerically the propagation of fronts through sinusoidally modulated channels
and tubes with period length L using the Schlögl model as an example. We map the
reaction-diffusion equation for the corrugated geometry onto a regular grid and, finally,
solve it numerically. The numerical simulations demonstrate that our analytical results
predict properly the nonlinear dependence of the propagation velocity on the ratio of
the spatial period of the cross-section’s modulation to the intrinsic width of the front,
including propagation failure.
[1] S. Martens, J. Löber, and H. Engel, Phys. Rev. E, 91, 022902 (2015).
[2] J. Löber and H. Engel, Phys. Rev. Lett., 112, 148305 (2014).
50
Wittenberg 2015
Venue
Venue
The Workshop on Control of Self-Organizing Nonlinear Systems will take place
in LEUCOREA, Lutherstadt Wittenberg
(Collegienstraße 62, 06886 Lutherstadt Wittenberg, Germany).
Conference Center
The LEUCOREA building is located in the south east of Wittenberg’s historic
center, between Collegienstraße and Wallstraße.
The lecture room will be the “Audimax” at LEUCOREA.
Breakfast, lunch and dinner
For all participants housed in LEUCOREA, breakfast will be served in the cafeteria on the first floor. Participants staying in Luther-Hotel Wittenberg will
have their breakfast at the hotel.
Lunch and dinner will be served in the cafeteria of LEUCOREA for all participants.
The conference dinner on Tuesday evening will be served at the restaurant
“Haus des Handwerks” (Collegienstraße 53a, 06886 Lutherstadt Wittenberg).
51
Venue
Wittenberg 2015
Oral presentations
All contributed oral presentations will last 15 min plus 5 min for questions. All
speakers are invited to test their laptops during the coffee breaks. The projector
will be equipped with a VGA cable.
Poster presentations
The poster session on Monday evening will take place in the seminar rooms 1
and 2 on the first floor. To mount the posters, pins will be provided. Posters
should be in DIN A0 format (84 cm wide and 120 cm high).
Transport
Coach Berlin - Wittenberg
Transportation by coach will be provided from and to Berlin.
Bus transfer:
Monday, September 14th
Berlin → Lutherstadt Wittenberg
Departure: 8:30am, Zoologischer Garten (Hardenbergplatz, bus parking area in
front of the train station), Berlin
Wednesday, September 16th
Lutherstadt Wittenberg → Berlin
Departure: 3:30pm
Expected arrival: 6:00pm, Zoologischer Garten, Berlin
WiFi/WLAN
Free wireless internet will be available. You are invited to bring your laptop and
make use of the wireless connection.
WiFi network guide for the workshop
1. Connect to the WiFi (or SSID) “Event-Net” network.
2. Activate the dynamic IP configuration (DHCP). It is very common to have
dynamic configuration set on the wireless interfaces. Typically it will not
be necessary to perform this step.
3. No username is required. Enter the password event-pw1 in the appropriate
field.
If you have an eduroam account, you may connect to the network “eduroam”
with your own login credentials.
52
Wittenberg 2015
Non-scientific program
Tuesday, September 15th: Excursions
In addition to the scientific program, you may choose between three different
guided tours around Wittenberg and a canoe tour. All excursions start on
Tuesday at 4:00pm, leaving from LEUCOREA.
Please register for one of the excursions on the registration lists in Audimax on
Monday. Please note that the canoe tour is limited to 20 participants (in case
of more than 20 interested participants: decision by drawing lots).
The guided tours through Wittenberg will end in the city of Wittenberg. The
canoe tour participants will be transfered direct to the conference dinner restaurant.
1. On tour with Barbara Cranach & Katharina von Bora
(starting at 4:00pm, English language)
Join the wives of Martin Luther and Lucas Cranach on a city tour through
Lutherstadt Wittenberg. Anno 1535 – Come on a comfortable walking tour
with the noble wives of Lucas Cranach and Martin Luther. Barbara and
Katharina know entertaining and interesting stories that cannot be found
in any guidebook. Experience the private life during the Reformation time
in Lutherstadt Wittenberg. Look into the bright eyes of Barbara while
talking about her new fur coat or listen to Katharina’s loud heartbeat
while talking about her first great love. (duration: 1 hour)
2. Auf den Spuren von Lucas Cranach
(starting at 4:00pm, German language)
Lucas Cranach war als Hofmaler, Bürgermeister, Drucker und Buchhändler
sowie als Freund Martin Luthers eine Schlüsselfigur für die Ausbreitung
53
Wittenberg 2015
der Reformation. Bei einem Gang entlang der historischen Meile in der
Lutherstadt Wittenberg werden zusätzlich zur Geschichte der Reformation
die zwei Häuser Cranachs gezeigt, sein Wirken als Drucker und Verleger
und die von ihm geschaffenen Bilder und Holzschnitte vorgestellt. Das
Werk Lucas Cranachs des Jüngeren wird ebenfalls erläutert. (duration:
1.5 hours)
3. Marie’s Bierbraureise
(starting at 4:00pm, German language)
Erleben Sie die Geschichte der Braukunst im historischen Wittenberg und
freuen Sie sich auf lehrreiche und lustige Unterhaltung mit Marie dem
Waschweib. Hören Sie auf einem Rundgang durch die mittelalterlichen
Gassen, Geschichte und Geschichten aus dem Wittenberg des 16. Jahrhunderts und von der Kunst zum Gelingen des guten Gerstensaftes. Anschließend begleiten Sie Marie durch die Wittenberger Brauerei und genießen Sie die Verkostung der aktuellen Sorten. (duration: 1.5 hours)
4. Canoe tour from Elster to Wittenberg
(starting at 4:00pm)
You will be transferred by bus to the starting point of the tour in Elster
and canoeing back to Wittenberg on the river Elbe. Be sure to wear
comfortable clothing and possibly take sun glasses / hat / towel / et
cetera with you. (duration: 1.5 hours + transfer)
54
Wittenberg 2015
Vadim Anishchenko (B11)
Saratov State University, Russia
Roland Aust (Z)
Institut für Theoretische Physik, TU Berlin
Stanislav Ax (Z)
Markus Bär (B5)
Physikalisch-Technische Bundesanstalt, Berlin
Jason Bassett (B10)
p. 34
Fabian Baumann (B8)
p. 35
Neural Information Processing Group, TU Berlin
Maximilian Becker (B5)
Nikita Begun (A9)
p. 36
Institut für Mathematik, FU Berlin
Vitaly Belik (B10)
Konstantin Blyuss
p. 37
University of Sussex, UK
Fabian Böhm (B9)
p. 38
Martin Brokate
p. 32
Technische Universität München
55
Wittenberg 2015
Alexander Carmele (B1)
Mark Curran (A9)
p. 31
Jan Danckaert
p. 16
Vrije Universiteit Brussel, Belgium
Leon Droenner (B1)
André Eikmeier (A8 )
p. 39
Institut für Mathematik, TU Berlin
Etienne Emmrich (A8 )
Harald Engel (B6)
Georg Engelhardt (A7 )
p. 19
Sebastian Eydam (A3)
Weierstraß-Institut, Berlin
Alexander Fengler (B10)
Sascha Gerloff (B2)
Pavel Gurevich (A9)
56
p. 11
p. 40
Wittenberg 2015
Sven Moritz Hein (B1)
p. 41
Philipp Hövel (B10)
Thomas Isele (B10)
Julia Kabuß (B1)
p. 18
Peter Kalle (B4)
p. 12
Sabine Klapp (B2)
Andreas Koher (B10)
p. 27
Wassilij Kopylov (A7 )
p. 42
Manuel Kraft (B1)
Christian Kreusler (A8 )
Sanjukta Krishnagopal
Birla Institute of Technology and Science, India
Yuliya Kyrychko
p. 26
University of Sussex, UK
57
Wittenberg 2015
Josef Ladenbauer (B8)
p. 28
Laurent Larger
p. 22
UMR CNRS FEMTO-ST, France
Robert Lasarzik (A8 )
p. 29
Judith Lehnert (A1)
Kathy Lüdge (B9)
Institut für Theoretische Physik, FU Berlin
Yuriy Maistrenko
The National Academy of Sciences of Ukraine, Ukraine
Steffen Martens (B6)
p. 13
Maria Masoliver Vila (A1)
Volker Mehrmann (A2)
p. 30
Alexander Mielke (A5)
Nicolas Naumann (B1)
p. 43
Thomas Niedermayer (B5)
p. 14
58
Wittenberg 2015
Klaus Obermayer (B8)
Iryna Omelchenko (A1)
p. 9
Viola Paschke (A2)
Dmitry Puzyrev (A3)
p. 23
Sina Reichelt (A5)
p. 20
André Röhm (B9)
p. 17
Felix Rühle (B4)
p. 44
Christopher Ryll (B6)
Jakub Sawicki (A1)
p. 45
Isabelle Schneider (A4)
p. 21
Eckehard Schöll (A1)
Igor Shepelev (B11)
p. 46
59
Wittenberg 2015
Ken Showalter
p. 8
West Virginia University, USA
Andrei Slepnev (B11)
p. 10
Yuya Tokuta (A4)
Liudmila Tumash (A1)
Benjamin Unger (A2)
p. 47
Tatjana Vadivasova (B11)
Nicola Vassena (A4)
p. 48
Matthias Wolfrum (A3)
p. 49
Serghiy Yanchuk (A3)
Anna Zakharova (A1)
Konstantinos Zemas (A9)
Alexander Ziepke (B6)
60
p. 50
Monday,
September 14th
Settle in, coffee
Welcome address
K. Showalter (invited)
Lunch
I. Omelchenko (A1)
A.V. Slepnev (B11)
S. Gerloff (B2)
Coffee break
P. Kalle (B4)
S. Martens (B6)
T. Niedermayer (B5)
Coffee break
Poster session
8:30 Bus travel from parking lot
Zoologischer Garten
Berlin → Wittenberg
10:30 Arrival
11:15
11:30
11:50
12:35
14:00
14:20
14:40
15:00
15:30
15:50
16:10
16:30
16:50
19:00 Dinner
20:30 Conference concert
8:00
9:00
9:45
10:15
10:35
10:55
11:15
11:45
12:05
12:25
14:00
14:45
15:05
15:30
Tuesday,
September 15th
Breakfast
J. Danckaert (invited)
Coffee break
A. Röhm (B9)
J. Kabuß (B1)
G. Engelhardt (A7)
Coffee break
S. Reichelt (A5)
I. Schneider (A4)
Group photo
Lunch
L. Larger (invited)
D. Puzyrev (A3)
Coffee break
Meeting of Principal
Investigators
16:30 Excursions
18:30
19:00 Conference Dinner
8:00
9:00
9:45
10:15
10:35
10:55
11:25
11:45
12:05
12:25
14:00
Wednesday,
September 16th
Breakfast
Y. Kyrychko (invited)
Coffee break
A. Koher (B10)
J. Ladenbauer (B8)
Coffee break
R. Lasarzik (A8)
V. Mehrmann (A2)
M. Curran (A9)
Lunch
Martin Brokate (invited)
14:45 Closing remarks
15:30 Departure by bus
18:00 Arrival in Berlin

here - Institut für Theoretische Physik

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