TY  - JOUR
A1  - Winterhalder, Matthias
A1  - Schelter, B
A1  - Kurths, Jürgen
A1  - Schulze-Borthage, A
A1  - Timmer, Jens
T1  - Sensitivity and specificity of coherence and phase synchronization analysis
N2  - In this Letter, we show that coherence and phase synchronization analysis are sensitive but not specific in detecting the correct class of underlying dynamics. We propose procedures to increase specificity and demonstrate the power of the approach by application to paradigmatic dynamic model systems. (c) 2006 Elsevier B.V. All rights reserved
Y1  - 2006
UR  - http://www.sciencedirect.com/science/article/pii/S0375960106004002 ( 11.07.2011]
U6  - https://doi.org/10.1016/j.physleta.2006.03.018
ER  - 
TY  - JOUR
A1  - Vasconcelos, D. B.
A1  - Lopes, S. R.
A1  - Viana, R. L.
A1  - Kurths, Jürgen
T1  - Spatial recurrence plots
N2  - We propose an extension of the recurrence plot concept to perform quantitative analyzes of roughness and disorder of spatial patterns at a fixed time. We introduce spatial recurrence plots (SRPs) as a graphical representation of the pointwise correlation matrix, in terms of a two-dimensional spatial return plot. This technique is applied to the study of complex patterns generated by coupled map lattices, which are characterized by measures of complexity based on SRPs. We show that the complexity measures we propose for SRPs provide a systematic way of investigating the distribution of spatially coherent structures, such as synchronization domains, in lattice profiles. This approach has potential for many more applications, e.g., in surface roughness analyzes
Y1  - 2006
UR  - http://pre.aps.org/pdf/PRE/v73/i5/e056207
U6  - https://doi.org/10.1103/Physreve.73.056207
ER  - 
TY  - BOOK
A1  - Voss, Henning U.
A1  - Kurths, Jürgen
A1  - Schwarz, Udo
T1  - Reconstruction of grand minima of solar activity from radiocarbon data : linear and nonlinear signal analysis
T3  - Preprint NLD
Y1  - 1996
VL  - 28
PB  - Univ.
CY  - Potsdam
ER  - 
TY  - BOOK
A1  - Feudel, Ulrike
A1  - Kurths, Jürgen
A1  - Neiman, Alexander
T1  - The cumulant approach for investigating the noise influence on mode-locking bifurcations
T3  - Preprint NLD
Y1  - 1995
VL  - 16
PB  - Univ.
CY  - Potsdam
ER  - 
TY  - BOOK
A1  - Rosenblum, Michael
A1  - Kurths, Jürgen
T1  - A model of neural control of heart rate
T3  - Preprint NLD
Y1  - 1995
VL  - 12
PB  - Univ.
CY  - Potsdam
ER  - 
TY  - JOUR
A1  - Kurths, Jürgen
A1  - Schwarz, Udo
A1  - Parlitz, Ulrich
A1  - Sonett, Charles P.
T1  - Testing for nonlinearity in radiocarbon data
N2  - The radiocarbon record that has been extended from 7199 BC to 1891 AD is of fundamental importance to understand century-scale variations of solar activity. We have, therefore, studied how to extract information from dynamic reconstructions of this observational record. Using some rather unusual methods of nonlinear dynamics, we have found that the data are significantly different from linear colored noise and that there is some evidence of nonlinear behavior. The method of recurrence plots exhibits that the grand minima of solar activity are quite different in their recurrence. Most remarkably, it suggests that the recent epoch seems to be similar to the Medieval maximum.
Y1  - 1994
UR  - http://www.agnld.uni-potsdam.de/~shw/Paper/n.ps.gz
SN  - 1023-5809
ER  - 
TY  - GEN
A1  - Allefeld, Carsten
A1  - Kurths, Jürgen
T1  - Testing for phase synchronization
N2  - We present different tests for phase synchronization which improve the procedures currently used in the literature. This is accomplished by using a two-samples test setup and by utilizing insights and methods from directional statistics and bootstrap theory. The tests differ in the generality of the situation in which they can be applied as well as in their complexity, including computational cost. A modification of the resampling technique of the bootstrap is introduced, making it possible to fully utilize data from time series.
T3  - Zweitveröffentlichungen der Universität Potsdam : Mathematisch-Naturwissenschaftliche Reihe - paper 071 
Y1  - 2004
U6  - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:kobv:517-opus-20091
ER  - 
TY  - GEN
A1  - Thiel, Marco
A1  - Romano, Maria Carmen
A1  - Kurths, Jürgen
A1  - Rolfs, Martin
A1  - Kliegl, Reinhold
T1  - Generating Surrogates from Recurrences
N2  - In this paper we present an approach to recover the dynamics from recurrences of a system and then generate (multivariate) twin surrogate (TS) trajectories. In contrast to other approaches, such as the linear-like surrogates, this technique produces surrogates which correspond to an independent copy of the underlying system, i. e. they induce a trajectory of the underlying system visiting the attractor in a different way. We show that these surrogates are well suited to test for complex synchronization, which makes it possible to systematically assess the reliability of synchronization analyses. We then apply the TS to study binocular fixational movements and find strong indications that the fixational movements of the left and right eye are phase synchronized. This result indicates that there might be one centre only in the brain that produces the fixational movements in both eyes or a close link between two centres.
T3  - Zweitveröffentlichungen der Universität Potsdam : Humanwissenschaftliche Reihe - paper 238 
KW  - Æ Recurrence Plots
KW  - Surrogate Data
KW  - Hypothesis Test
KW  - Phase Synchronization
Y1  - 2006
U6  - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:kobv:517-opus-56906
ER  - 
TY  - GEN
A1  - Koseska, Aneta
A1  - Zaikin, Alexey
A1  - Kurths, Jürgen
A1  - García-Ojalvo, Jordi
T1  - Timing cellular decision making under noise via cell-cell communication
N2  - Many cellular processes require decision making mechanisms, which must act reliably even in the unavoidable presence of substantial amounts of noise. However, the multistable genetic switches that underlie most decision-making processes are dominated by fluctuations that can induce random jumps between alternative cellular states. Here we show, via theoretical modeling of a population of noise-driven bistable genetic switches, that reliable timing of decision-making processes can be accomplished for large enough population sizes, as long as cells are globally coupled by chemical means. In the light of these results, we conjecture that cell proliferation, in the presence of cell-cell communication, could provide a mechanism for reliable decision making in the presence of noise, by triggering cellular transitions only when the whole cell population reaches a certain size. In other words , the summation performed by the cell population would average out the noise and reduce its detrimental impact.
T3  - Zweitveröffentlichungen der Universität Potsdam : Mathematisch-Naturwissenschaftliche Reihe - paper 148 
Y1  - 2009
U6  - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:kobv:517-opus-45260
ER  - 
TY  - GEN
A1  - Allefeld, Carsten
A1  - Kurths, Jürgen
T1  - An approach to multivariate phase synchronization analysis and its application to event-related potentials
N2  - A method for the multivariate analysis of statistical phase synchronization phenomena in empirical data is presented. A first statistical approach is complemented by a stochastic dynamic model, to result in a data analysis algorithm which can in a specific sense be shown to be a generic multivariate statistical phase synchronization analysis. The method is applied to EEG data from a psychological experiment, obtaining results which indicate the relevance of this method in the context of cognitive science as well as in other fields.
T3  - Zweitveröffentlichungen der Universität Potsdam : Mathematisch-Naturwissenschaftliche Reihe - paper 069 
Y1  - 2004
U6  - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:kobv:517-opus-20106
ER  - 
TY  - INPR
A1  - Pikovskij, Arkadij
A1  - Zaks, Michael A.
A1  - Feudel, Ulrike
A1  - Kurths, Jürgen
T1  - Singular continuous spectra in dissipative dynamics
N2  - We demonstrate the occurrence of regimes with singular continuous (fractal) Fourier spectra in autonomous dissipative dynamical systems. The particular example in an ODE system at the accumulation points of bifurcation sequences associated to the creation of complicated homoclinic orbits. Two different machanisms responsible for the appearance of such spectra are proposed. In the first case when the geometry of the attractor is symbolically represented by the Thue-Morse sequence, both the continuous-time process and its descrete Poincaré map have singular power spectra. The other mechanism owes to the logarithmic divergence of the first return times near the saddle point; here the Poincaré map possesses the discrete spectrum, while the continuous-time process displays the singular one. A method is presented for computing the multifractal characteristics of the singular continuous spectra with the help of the usual Fourier analysis technique.
T3  - NLD Preprints - 15 
Y1  - 1995
U6  - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:kobv:517-opus-13787
ER  - 
TY  - INPR
A1  - Engbert, Ralf
A1  - Scheffczyk, Christian
A1  - Krampe, Ralf-Thomas
A1  - Rosenblum, Mikhael
A1  - Kurths, Jürgen
A1  - Kliegl, Reinhold
T1  - Tempo-induced transitions in polyrhythmic hand movements
N2  - We investigate the cognitive control in polyrhythmic hand movements as a model paradigm for bimanual coordination. Using a symbolic coding of the recorded time series, we demonstrate the existence of qualitative transitions induced by experimental manipulation of the tempo. A nonlinear model with delayed feedback control is proposed, which accounts for these dynamical transitions in terms of bifurcations resulting from variation of the external control parameter. Furthermore, it is shown that transitions can also be observed due to fluctuations in the timing control level. We conclude that the complexity of coordinated bimanual movements results from interactions between nonlinear control mechanisms with delayed feedback and stochastic timing components.
T3  - NLD Preprints - 41 
Y1  - 1997
U6  - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:kobv:517-opus-14380
ER  - 
TY  - INPR
A1  - Voss, Henning
A1  - Kurths, Jürgen
A1  - Schwarz, Udo
T1  - Reconstruction of grand minima of solar activity from Delta 14 C data : linear and nonlinear signal analysis
N2  - Using a special technique of data analysis, we have found out 34 grand minima of solar activity obtained from a 7,700 years long Δ14C record. The method used rests on a proper filtering of the Δ14C record and the extrapolation of verifiable results for the later history back in time. Additionally, we use a method of nonlinear dynamics, the recurrence rate, to back up the results. Our findings are not contradictory to the record of solar maxima resp. minima by Eddy [5], but constitute a considerable extension. Hence, it has become possible to look closer at the validity of models. This way, we have tested several models for solar activity, esp. the model of Barnes et al. [1]. There are hints for that the grand minima might solely be driven by the 209 year period found in the Δ14C record.
T3  - NLD Preprints - 28 
Y1  - 1996
U6  - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:kobv:517-opus-14083
ER  - 
TY  - INPR
A1  - Thiessenhusen, Kai-Uwe
A1  - Esposito, Larry W.
A1  - Kurths, Jürgen
A1  - Spahn, Frank
T1  - Detection of hidden resonances in Saturn's B-ring
N2  - The Voyager 2 Photopolarimeter experiment has yielded the highest resolved data of Saturn's rings, exhibiting a wide variety of features. The B-ring region between 105000 km and 110000 km distance from Saturn has been investigated. It has a high matter density and contains no significance features visible by eye. Analysis with statistical methods has let us to the detection of two significant events. These features are correlated with the inner 3:2 resonances of the F-ring shepherd satellites Pandora and Prometheus, and may be evidence of large ring paricles caught in the corotation resonances.
T3  - NLD Preprints - 13 
KW  - Planetary Rings
Y1  - 1995
U6  - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:kobv:517-opus-13618
ER  - 
TY  - INPR
A1  - Witt, Annette
A1  - Neiman, Alexander
A1  - Kurths, Jürgen
T1  - Characterizing the dynamics of stochastic bistable systems by measures of complexity
N2  - The dynamics of noisy bistable systems is analyzed by means of Lyapunov exponents and measures of complexity. We consider both the classical Kramers problem with additive white noise and the case when the barrier fluctuates due to additional external colored noise. In case of additive noise we calculate the Lyapunov exponents and all measures of complexity analytically as functions of the noise intensity resp. the mean escape time. For the problem of fluctuating barrier the usual description of the dynamics with the mean escape time is not sufficient. The application of the concept of measures of complexity allows to describe the structures of motion in more detail. Most complexity measures sign the value of correlation time at which the phenomenon of resonant activation occurs with an extremum.
T3  - NLD Preprints - 36 
Y1  - 1997
U6  - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:kobv:517-opus-14556
ER  - 
TY  - INPR
A1  - Guasti, Giovanna
A1  - Engbert, Ralf
A1  - Krampe, Ralf T.
A1  - Kurths, Jürgen
T1  - Phase transitions, complexity, and stationarity in the production of polyrhythms
N2  - Contents: 1 Introduction 2 Experiment 3 Data 4 Symbolic dynamics 4.1 Symbolic dynamics as a tool for data analysis 4.2 2-symbols coding 4.3 3-symbols coding 5 Measures of complexity 5.1 Word statistics 5.2 Shannon entropy 6 Testing for stationarity 6.1 Stationarity 6.2 Time series of cycle durations 6.3 Chi-square test 7 Control parameters in the production of rhythms 8 Analysis of relative phases 9 Discussion 10 Outlook
T3  - NLD Preprints - 57 
Y1  - 2000
U6  - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:kobv:517-opus-14933
ER  - 
TY  - GEN
A1  - Thiel, Marco
A1  - Romano, Maria Carmen
A1  - Kurths, Jürgen
A1  - Rolfs, Martin
T1  - Twin Surrogates to Test for Complex Synchronisation
N2  - We present an approach to generate (multivariate) twin surrogates (TS) based on recurrence properties. This technique generates surrogates which correspond to an independent copy of the underlying system, i. e. they induce a trajectory of the underlying system starting at different initial conditions. We show that these surrogates are well suited to test for complex synchronisation and exemplify this for the paradigmatic system of R¨ossler oscillators. The proposed test enables to assess the statistical relevance of a synchronisation analysis from passive experiments which are typical in natural systems.
T3  - Zweitveröffentlichungen der Universität Potsdam : Humanwissenschaftliche Reihe - paper 264 
Y1  - 2006
U6  - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:kobv:517-opus-57231
ER  - 
TY  - JOUR
A1  - Breitenbach, Sebastian Franz Martin
A1  - Rehfeld, Kira
A1  - Goswami, Bedartha
A1  - Baldini, James U. L.
A1  - Ridley, H. E.
A1  - Kennett, D. J.
A1  - Prufer, K. M.
A1  - Aquino, Valorie V.
A1  - Asmerom, Yemane
A1  - Polyak, V. J.
A1  - Cheng, Hai
A1  - Kurths, Jürgen
A1  - Marwan, Norbert
T1  - Constructing Proxy Records from Age models (COPRA)
JF  - Climate of the past : an interactive open access journal of the European Geosciences Union
N2  - Reliable age models are fundamental for any palaeoclimate reconstruction. Available interpolation procedures between age control points are often inadequately reported, and very few translate age uncertainties to proxy uncertainties. Most available modeling algorithms do not allow incorporation of layer counted intervals to improve the confidence limits of the age model in question.
 We present a framework that allows detection and interactive handling of age reversals and hiatuses, depth-age modeling, and proxy-record reconstruction. Monte Carlo simulation and a translation procedure are used to assign a precise time scale to climate proxies and to translate dating uncertainties to uncertainties in the proxy values. The presented framework allows integration of incremental relative dating information to improve the final age model. The free software package COPRA1.0 facilitates easy interactive usage.
Y1  - 2012
U6  - https://doi.org/10.5194/cp-8-1765-2012
SN  - 1814-9324
VL  - 8
IS  - 5
SP  - 1765
EP  - 1779
PB  - Copernicus
CY  - Göttingen
ER  - 
TY  - JOUR
A1  - Ozturk, Ugur
A1  - Marwan, Norbert
A1  - Korup, Oliver
A1  - Saito, H.
A1  - Agarwa, Ankit
A1  - Grossman, M. J.
A1  - Zaiki, M.
A1  - Kurths, Jürgen
T1  - Complex networks for tracking extreme rainfall during typhoons
JF  - Chaos : an interdisciplinary journal of nonlinear science
N2  - Reconciling the paths of extreme rainfall with those of typhoons remains difficult despite advanced forecasting techniques. We use complex networks defined by a nonlinear synchronization measure termed event synchronization to track extreme rainfall over the Japanese islands. Directed networks objectively record patterns of heavy rain brought by frontal storms and typhoons but mask out contributions of local convective storms. We propose a radial rank method to show that paths of extreme rainfall in the typhoon season (August-November, ASON) follow the overall southwest-northeast motion of typhoons and mean rainfall gradient of Japan. The associated eye-of-the-typhoon tracks deviate notably and may thus distort estimates of heavy typhoon rainfall. We mainly found that the lower spread of rainfall tracks in ASON may enable better hindcasting than for westerly-fed frontal storms in June and July.
Y1  - 2018
U6  - https://doi.org/10.1063/1.5004480
SN  - 1054-1500
SN  - 1089-7682
VL  - 28
IS  - 7
PB  - American Institute of Physics
CY  - Melville
ER  - 
TY  - JOUR
A1  - Zhou, Changsong
A1  - Kurths, Jürgen
T1  - Noise-sustained and controlled synchronization of stirred excitable media by external forcing
N2  - Most of the previous studies on constructive effects of noise in spatially extended systems have focused on static media, e.g., of the reaction diffusion type. Because many active chemical or biological processes occur in a fluid environment with mixing, we investigate here the interplay among noise, excitability, mixing and external forcing in excitable media advected by a chaotic flow, in a two-dimensional FitzHugh-Nagumo model described by a set of reaction- advection-diffusion equations. In the absence of external forcing, noise may generate sustained coherent oscillations of the media in a range of noise intensities and stirring rates. We find that these noise-sustained oscillations can be synchronized by external periodic signals much smaller than the threshold. Analysis of the locking regions in the parameter space of the signal period, stirring rate and noise intensity reveals that the mechanism underlying the synchronization behaviour is a matching between the time scales of the forcing signal and the noise-sustained oscillations. The results demonstrate that, in the presence of a suitable level of noise, the stirred excitable media act as self-sustained oscillatory systems and become much easier to be entrained by weak external forcing. Our results may be verified in experiments and are useful to understand the synchronization of population dynamics of oceanic ecological systems by annual cycles
Y1  - 2005
SN  - 1367-2630
ER  - 
TY  - JOUR
A1  - Vincent, Uchechukwu E.
A1  - Kenfack, Anatole
A1  - Senthilkumar, Dharmapuri Vijayan
A1  - Mayer, Dieter
A1  - Kurths, Jürgen
T1  - Current reversals and synchronization in coupled ratchets
N2  - Current reversal is an intriguing phenomenon that has been central to recent experimental and theoretical investigations of transport based on ratchet mechanism. By considering a system of two interacting ratchets, we demonstrate how the coupling can be used to control the reversals. In particular, we find that current reversal that exists in a single driven ratchet system can ultimately be eliminated with the presence of a second ratchet. For specific coupling strengths a current-reversal free regime has been detected. Furthermore, in the fully synchronized state characterized by the coupling threshold k(th), a specific driving amplitude a(opt) is found for which the transport is optimum.
Y1  - 2010
UR  - http://pre.aps.org/
U6  - https://doi.org/10.1103/Physreve.82.046208
SN  - 1539-3755
ER  - 
TY  - JOUR
A1  - Zhang, H.
A1  - Hu, B.
A1  - Hu, G.
A1  - Ouyang, Q.
A1  - Kurths, Jürgen
T1  - Turbulence control by developing a spiral wave with a periodic signal injection in the complex Ginzburg-Laundau equation
Y1  - 2002
ER  - 
TY  - JOUR
A1  - Bittmann, Frank
A1  - Gutschow, Stephan
A1  - Luther, Sven
A1  - Wessel, Niels
A1  - Kurths, Jürgen
T1  - On the functional relationship between postural motor balance and performance at school
N2  - In integrated medical considerations of the biological human system, both intellectual and motor performances in a similar manner are considered as a result of the function of the nervous system. Consequently, universal minimal dysfunctions of the central nervous system may lead to both intellectual and physical anomalies. Therefore, this study tests the hypothesis that there is a connection between the balance ability as a motor parameter and school success as an intellectual parameter. A postural measuring system based on the force-moment sensor technique was used to record the postural balance regulation of 773 children (circle divide 11 +/- 1 years). The school achievement of each child was determined by school grades. Data analysis was performed by linear as well as by nonlinear time series analyses. There are highly significant differences in balance regulation between good and poor pupils recognized by several linear and nonlinear parameters. Good pupils could be discriminated from pupils with bad results in learning to 80 %. The results support the hypothesis mentioned above. One possible explanation for the poor regulation of balance in bad learners could be a deficit in the neural maturity. In future, further developments will be targeted on higher discrimination levels, possibly in order to predict school success. On the other hand, the effects of special movement exercises on the neural development in childhood will be the focus in our further work
Y1  - 2005
ER  - 
TY  - JOUR
A1  - Feudel, Fred
A1  - Witt, Annette
A1  - Gellert, Marcus
A1  - Kurths, Jürgen
A1  - Grebogi, Celso
A1  - Sanjuan, Miguel Angel Fernandez
T1  - Intersections of stable and unstable manifolds : the skeleton of Lagrangian chaos
N2  - We study Hamiltonian chaos generated by the dynamics of passive tracers moving in a two-dimensional fluid flow and describe the complex structure formed in a chaotic layer that separates a vortex region from the shear flow. The stable and unstable manifolds of unstable periodic orbits are computed. It is shown that their intersections in the Poincare map as an invariant set of homoclinic points constitute the backbone of the chaotic layer. Special attention is paid to the finite time properties of the chaotic layer. In particular, finite time Lyapunov exponents are computed and a scaling law of the variance of their distribution is derived. Additionally, the box counting dimension as an effective dimension to characterize the fractal properties of the layer is estimated for different duration times of simulation. Its behavior in the asymptotic time limit is discussed. By computing the Lyapunov exponents and by applying methods of symbolic dynamics, the formation of the layer as a function of the external forcing strength, which in turn represents the perturbation of the originally integrable system, is characterized. In particular, it is shown that the capture of KAM tori by the layer has a remarkable influence on the averaged Lyapunov exponents. (C) 2004 Elsevier Ltd. All rights reserved
Y1  - 2005
ER  - 
TY  - JOUR
A1  - Baptista, Murilo da Silva
A1  - Pereira, Tiago
A1  - Sartorelli, J. C.
A1  - Caldas, Ibere Luiz
A1  - Kurths, Jürgen
T1  - Non-transitive maps in phase synchronization
N2  - Concepts from Ergodic Theory are used to describe the existence of special non-transitive maps in attractors of phase synchronous chaotic oscillators. In particular, it is shown that, for a class of phase-coherent oscillators, these special maps imply phase synchronization. We illustrate these ideas in the sinusoidally forced Chua's circuit and two coupled Rossler oscillators. Furthermore, these results are extended to other coupled chaotic systems. In addition, a phase for a chaotic attractor is defined from the tangent vector of the flow. Finally, it is discussed how these maps can be used for the real-time detection of phase synchronization in experimental systems. (c) 2005 Elsevier B.V. All rights reserved
Y1  - 2005
ER  - 
TY  - JOUR
A1  - Kitajima, H.
A1  - Kurths, Jürgen
T1  - Synchronized firing of FitzHugh-Nagumo neurons by noise
N2  - We investigate the influence of noise on synchronization between the spiking activities of neurons with external impulsive forces. We first analyze the dependence of the synchronized firing on the amplitude and the angular frequency of the impulsive force in the noise-free system. Three cases (regular spiking, traveling wave, and chaotic spiking) with low synchronized firing are chosen to study effects due to noise. In each case we find that small noise can be a promoter of synchronization phenomena in neural activities, by choosing an appropriate noise intensity acting on some of the neurons. (C) 2005 American Institute of Physics
Y1  - 2005
SN  - 1054-1500
ER  - 
TY  - JOUR
A1  - Baptista, Murilo da Silva
A1  - Kurths, Jürgen
T1  - Chaotic channel
N2  - This work combines the theory of chaotic synchronization with the theory of information in order to introduce the chaotic channel, an active medium formed by connected chaotic systems. This subset of a large chaotic net represents the path along which information flows. We show that the possible amount of information exchange between the transmitter, where information enters the net, and the receiver, the destination of the information, is proportional to the level of synchronization between these two special subsystems
Y1  - 2005
SN  - 1539-3755
ER  - 
TY  - JOUR
A1  - Ziehmann, Christine
A1  - Smith, L.
A1  - Kurths, Jürgen
T1  - The bootstrap and lyapunov exponents in deterministic chaos
Y1  - 1999
ER  - 
TY  - JOUR
A1  - Wessel, Niels
A1  - Konvicka, Jan
A1  - Weidermann, Frank
A1  - Nestmann, S.
A1  - Neugebauer, R.
A1  - Schwarz, U.
A1  - Wessel, A.
A1  - Kurths, Jürgen
T1  - Predicting thermal displacements in modular tool systems
N2  - In the last decade, there has been an increasing interest in compensating thermally induced errors to improve the manufacturing accuracy of modular tool systems. These modular tool systems are interfaces between spindle and workpiece and consist of several complicatedly formed parts. Their thermal behavior is dominated by nonlinearities, delay and hysteresis effects even in tools with simpler geometry and it is difficult to describe it theoretically. Due to the dominant nonlinear nature of this behavior the so far used linear regression between the temperatures and the displacements is insufficient. Therefore, in this study we test the hypothesis whether we can reliably predict such thermal displacements via nonlinear temperature-displacement regression functions. These functions are estimated firstly from learning measurements using the alternating conditional expectation (ACE) algorithm and then tested on independent data sets. First, we analyze data that were generated by a finite element spindle model. We find that our approach is a powerful tool to describe the relation between temperatures and displacements for simulated data. Next, we analyze the temperature-displacement relationship in a silent real experimental setup, where the tool system is thermally forced. Again, the ACE-algorithm is powerful to estimate the deformation with high precision. The corresponding errors obtained by using the nonlinear regression approach are 10-fold lower in comparison to multiple linear regression analysis. Finally, we investigate the thermal behavior of a modular tool system in a working milling machine and get again promising results. The thermally inducedaccuracy using this nonlinear regression analysis. Therefore, this approach seems to be very useful for the development of new modular tool systems. errors can be estimated with 1-2 micrometer
Y1  - 2004
SN  - 1054-1500
ER  - 
TY  - JOUR
A1  - Wessel, Niels
A1  - Aßmus, Joerg
A1  - Weidermann, Frank
A1  - Konvicka, Jan
A1  - Nestmann, S.
A1  - Neugebauer, R.
A1  - Schwarz, Udo
A1  - Kurths, Jürgen
T1  - Modeling thermal displacements in modular tool systems
N2  - In the last decade, there has been an increasing interest in compensating thermally induced errors to improve the manufacturing accuracy of modular tool systems. These modular tool systems are interfaces between spindle and workpiece and consist of several complicatedly formed parts. Their thermal behavior is dominated by nonlinearities, delay and hysteresis effects even in tools with simpler geometry and it is difficult to describe it theoretically. Due to the dominant nonlinear nature of this behavior the so far used linear regression between the temperatures and the displacements is insufficient. Therefore, in this study we test the hypothesis whether we can reliably predict such thermal displacements via nonlinear temperature-displacement regression functions. These functions are estimated firstly from learning measurements using the alternating conditional expectation (ACE) algorithm and then tested on independent data sets. First, we analyze data that were generated by a finite element spindle model. We find that our approach is a powerful tool to describe the relation between temperatures and displacements for simulated data. Next, we analyze the temperature-displacement relationship in a silent real experimental setup, where the tool system is thermally forced. Again, the ACE-algorithm is powerful to estimate the deformation with high precision. The corresponding errors obtained by using the nonlinear regression approach are 10-fold lower in comparison to multiple linear regression analysis. Finally, we investigate the thermal behavior of a modular tool system in a working milling machine and get again promising results. The thermally induced errors can be estimated with 1-2${mu m}$ accuracy using this nonlinear regression analysis. Therefore, this approach seems to be very useful for the development of new modular tool systems.
Y1  - 2004
ER  - 
TY  - JOUR
A1  - Zaikin, Alexei
A1  - Kurths, Jürgen
A1  - Saparin, Peter
A1  - Gowin, W.
A1  - Prohaska, Steffen
T1  - Modeling bone resorption in 2D CT and 3D mu CT images
N2  - We study several algorithms to simulate bone mass loss in two-dimensional and three-dimensional computed tomography bone images. The aim is to extrapolate and predict the bone loss, to provide test objects for newly developed structural measures, and to understand the physical mechanisms behind the bone alteration. Our bone model approach differs from those already reported in the literature by two features. First, we work with original bone images, obtained by computed tomography (CT); second, we use structural measures of complexity to evaluate bone resorption and to compare it with the data provided by CT. This gives us the possibility to test algorithms of bone resorption by comparing their results with experimentally found dependencies of structural measures of complexity, as well as to show efficiency of the complexity measures in the analysis of bone models. For two-dimensional images we suggest two algorithms, a threshold algorithm and a virtual slicing algorithm. The threshold algorithm simulates bone resorption on a boundary between bone and marrow, representing an activity of osteoclasts. The virtual slicing algorithm uses a distribution of the bone material between several virtually created slices to achieve statistically correct results, when the bone-marrow transition is not clearly defined. These algorithms have been tested for original CT 10 mm thick vertebral slices and for simulated 10 mm thick slices constructed from ten I mm thick slices. For three-dimensional data, we suggest a variation of the threshold algorithm and apply it to bone images. The results of modeling have been compared with CT images using structural measures of complexity in two- and three-dimensions. This comparison has confirmed credibility of a virtual slicing modeling algorithm for two-dimensional data and a threshold algorithm for three-dimensional data
Y1  - 2005
SN  - 0218-1274
ER  - 
TY  - JOUR
A1  - Orgis, Thomas
A1  - Brand, Sascha
A1  - Schwarz, Udo
A1  - Handorf, Dörthe
A1  - Dethloff, Klaus
A1  - Kurths, Jürgen
T1  - Influence of interactive stratospheric chemistry on large-scale air mass exchange in a global circulation model
N2  - A new globally uniform Lagrangian transport scheme for large ensembles of passive tracer particles is presented and applied to wind data from a coupled atmosphere-ocean climate model that includes interactive dynamical feedback with stratospheric chemistry. This feedback from the chemistry is found to enhance large-scale meridional air mass exchange in the northern winter stratosphere as well as intrusion of stratospheric air into the troposphere, where both effects are due to a weakened polar vortex.
Y1  - 2009
UR  - http://www.springerlink.com/content/1951-6355
U6  - https://doi.org/10.1140/epjst/e2009-01105-8
SN  - 1951-6355
ER  - 
TY  - JOUR
A1  - Viana, R. L.
A1  - Grebogi, Celso
A1  - Pinto, S. E. D.
A1  - Lopes, S. R.
A1  - Batista, A. M.
A1  - Kurths, Jürgen
T1  - Bubbling bifurcation : loss of synchronization and shadowing breakdown in complex systems
N2  - Complex dynamical systems with many degrees of freedom may exhibit a wealth of collective phenomena related to high-dimensional chaos. This paper focuses on a lattice of coupled logistic maps to investigate the relationship between the loss of chaos synchronization and the onset of shadowing breakdown via unstable dimension variability in complex systems. In the neighborhood of the critical transition to strongly non-hyperbolic behavior, the system undergoes on-off intermittency with respect to the synchronization manifold. This has been confirmed by numerical diagnostics of synchronization and non-hyperbolic behavior, the latter using the statistical properties of finite-time Lyapunov exponents. (c) 2005 Elsevier B.V. All rights reserved
Y1  - 2005
ER  - 
TY  - JOUR
A1  - Montbrio, Ernest
A1  - Kurths, Jürgen
A1  - Blasius, Bernd
T1  - Synchronization of two interacting populations of oscillators
N2  - We analyze synchronization between two interacting populations of different phase oscillators. For the important case of asymmetric coupling functions, we find a much richer dynamical behavior compared to that of symmetrically coupled populations of identical oscillators. It includes three types of bistabilities, higher order entrainment and the existence of states with unusual stability properties. All possible routes to synchronization of the populations are presented and some stability boundaries are obtained analytically. The impact of these findings for neuroscience is discussed.
Y1  - 2004
UR  - http://www.agnld.uni-potsdam.de/~bernd/papers/pre3.pdf
ER  - 
TY  - JOUR
A1  - Shabunin, A.
A1  - Astakhov, Vladimir V.
A1  - Kurths, Jürgen
T1  - Quantitative analysis of chaotic synchronization by means of coherence
N2  - We use an index of chaotic synchronization based on the averaged coherence function for the quantitative analysis of the process of the complete synchronization loss in unidirectionally coupled oscillators and maps. We demonstrate that this value manifests different stages of the synchronization breaking. It is invariant to time delay and insensitive to small noise and distortions, which can influence the accessible signals at measurements. Peculiarities of the synchronization destruction in maps and oscillators are investigated
Y1  - 2005
SN  - 1539-3755
ER  - 
TY  - JOUR
A1  - Sitz, Andre
A1  - Schwarz, Udo
A1  - Kurths, Jürgen
T1  - The unscented Kalman filter : a powerful tool for data analysis
Y1  - 2004
ER  - 
TY  - JOUR
A1  - Voss, Henning U.
A1  - Timmer, Jens
A1  - Kurths, Jürgen
T1  - Nonlinear dynamical system identification from uncertain and indirect measurements
N2  - We review the problem of estimating parameters and unobserved trajectory components from noisy time series measurements of continuous nonlinear dynamical systems. It is first shown that in parameter estimation techniques that do not take the measurement errors explicitly into account, like regression approaches, noisy measurements can produce inaccurate parameter estimates. Another problem is that for chaotic systems the cost functions that have to be minimized to estimate states and parameters are so complex that common optimization routines may fail. We show that the inclusion of information about the time-continuous nature of the underlying trajectories can improve parameter estimation considerably. Two approaches, which take into account both the errors-in-variables problem and the problem of complex cost functions, are described in detail: shooting approaches and recursive estimation techniques. Both are demonstrated on numerical examples
Y1  - 2004
SN  - 0218-1274
ER  - 
TY  - JOUR
A1  - Thiel, M.
A1  - Romano, Maria Carmen
A1  - Read, P. L.
A1  - Kurths, Jürgen
T1  - Estimation of dynamical invariants without embedding by recurrence plots
N2  - In this paper we show that two dynamical invariants, the second order Renyi entropy and the correlation dimension, can be estimated from recurrence plots (RPs) with arbitrary embedding dimension and delay. This fact is interesting as these quantities are even invariant if no embedding is used. This is an important advantage of RPs compared to other techniques of nonlinear data analysis. These estimates for the correlation dimension and entropy are robust and, moreover, can be obtained at a low numerical cost. We exemplify our results for the Rossler system, the funnel attractor and the Mackey-Glass system. In the last part of the paper we estimate dynamical invariants for data from some fluid dynamical experiments and confirm previous evidence for low dimensional chaos in this experimental system. (C) 2004 American Institute of Physics
Y1  - 2004
SN  - 1054-1500
ER  - 
TY  - JOUR
A1  - Maraun, Douglas
A1  - Kurths, Jürgen
T1  - Cross wavelet analysis: significance testing and pitfalls
N2  - In this paper, we present a detailed evaluation of cross wavelet analysis of bivariate time series. We develop a statistical test for zero wavelet coherency based on Monte Carlo simulations. If at least one of the two processes considered is Gaussian white noise, an approximative formula for the critical value can be utilized. In a second part, typical pitfalls of wavelet cross spectra and wavelet coherency are discussed. The wavelet cross spectrum appears to be not suitable for significance testing the interrelation between two processes. Instead, one should rather apply wavelet coherency. Furthermore we investigate problems due to multiple testing. Based on these results, we show that coherency between ENSO and NAO is an artefact for most of the time from 1900 to 1995. However, during a distinct period from around 1920 to 1940, significant coherency between the two phenomena occurs
Y1  - 2004
SN  - 1023-5809
ER  - 
TY  - JOUR
A1  - Thiel, M.
A1  - Romano, Maria Carmen
A1  - Kurths, Jürgen
T1  - How much information is contained in a recurrence plot?
N2  - Recurrence plots have recently been recognized as a powerful tool for the analysis of data. Not only the visualization of structures of the time series but also the possibility to estimate invariants from them and the possibility to analyze non-stationary data sets are remarkable. However, the question of how much information is encoded in such a two-dimensional and binary representation has not been discussed so far. In this Letter we show that-under some conditions-it is possible to reconstruct an attractor from the recurrence plot, at least topologically. This means that all relevant dynamical information is contained in the plot. (C) 2004 Elsevier B.V. All rights reserved
Y1  - 2004
SN  - 0375-9601
ER  - 
TY  - JOUR
A1  - Ivanchenko, Mikhail V.
A1  - Osipov, Grigory V.
A1  - Shalfeev, V. D.
A1  - Kurths, Jürgen
T1  - Phase synchronization in ensembles of bursting oscillators
N2  - We study the effects of mutual and external chaotic phase synchronization in ensembles of bursting oscillators. These oscillators (used for modeling neuronal dynamics) are essentially multiple time scale systems. We show that a transition to mutual phase synchronization takes place on the bursting time scale of globally coupled oscillators, while on the spiking time scale, they behave asynchronously. We also demonstrate the effect of the onset of external chaotic phase synchronization of the bursting behavior in the studied ensemble by a periodic driving applied to one arbitrarily taken neuron. We also propose an explanation of the mechanism behind this effect. We infer that the demonstrated phenomenon can be used efficiently for controlling bursting activity in neural ensembles
Y1  - 2004
SN  - 0031-9007
ER  - 
TY  - JOUR
A1  - Tokuda, I.
A1  - Kurths, Jürgen
A1  - Allaria, Eugenio
A1  - Meucci, Riccardo
A1  - Boccaletti, Stefano
A1  - Arecchi, Fortunato Tito
T1  - Predicting phase synchronization in a spiking chaotic CO2 laser
N2  - An approach is presented for the reconstruction of phase synchronization phenomena in a chaotic CO2 laser from experimental data. We analyze this laser system in a regime able to phase synchronize with a weak sinusoidal forcing. Our technique recovers the synchronization diagram of the experimental system from only few measurement data sets, thus allowing the prediction of the regime of phase synchronization as well as nonsynchronization in a broad parameter space of forcing frequency and amplitude without further experiments
Y1  - 2004
SN  - 1063-651X
ER  - 
TY  - JOUR
A1  - Ivanchenko, Mikhail V.
A1  - Osipov, Grigory V.
A1  - Shalfeev, V. D.
A1  - Kurths, Jürgen
T1  - Phase synchronization of chaotic intermittent oscillations
N2  - We study phase synchronization effects of chaotic oscillators with a type-I intermittency behavior. The external and mutual locking of the average length of the laminar stage for coupled discrete and continuous in time systems is shown and the mechanism of this synchronization is explained. We demonstrate that this phenomenon can be described by using results of the parametric resonance theory and that this correspondence enables one to predict and derive all zones of synchronization
Y1  - 2004
SN  - 0031-9007
ER  - 
TY  - JOUR
A1  - Rosenblum, Michael
A1  - Pikovskij, Arkadij
A1  - Kurths, Jürgen
T1  - Synchronization approach to analysis of biological systems
N2  - In this article we review the application of the synchronization theory to the analysis of multivariate biological signals. We address the problem of phase estimation from data and detection and quantification of weak interaction, as well as quantification of the direction of coupling. We discuss the potentials as well as limitations and misinterpretations of the approach
Y1  - 2004
SN  - 0219-4775
ER  - 
TY  - JOUR
A1  - Zaikin, Alexei A.
A1  - López, L
A1  - Baltanás, J. P.
A1  - Kurths, Jürgen
A1  - Sanjuan, Miguel Angel Fernández
T1  - Vibrational resonance in noise-induced structure
N2  - We report on the effect of vibrational resonance in a spatially extended system of coupled noisy oscillators under the action of two periodic forces, a low-frequency one (signal) and a high-frequency one (carrier). Vibrational resonance manifests itself in the fact that for optimally selected values of high-frequency force amplitude, the response of the system to a low-frequency signal is optimal. This phenomenon is a synthesis of two effects, a noise- induced phase transition leading to bistability, and a conventional vibrational resonance, resulting in the optimization of signal processing. Numerical simulations, which demonstrate this effect for an extended system, can be understood by means of a zero-dimensional "effective" model. The behavior of this "effective" model is also confirmed by an experimental realization of an electronic circuit.
Y1  - 2002
UR  - http://link.aps.org/abstract/PRE/v66/e011106
ER  - 
TY  - JOUR
A1  - Ebeling, Werner
A1  - Molgedey, Lutz
A1  - Kurths, Jürgen
A1  - Schwarz, Udo
T1  - Entropy, complexity, predictability, and data analysis of time series and letter sequences
N2  - The structure of time series and letter sequences is investigated using the concepts of entropy and complexity. First conditional entropy and transinformation are introduced and several generalizations are discussed. Further several measures of complexity are introduced and discussed. The capability of these concepts to describe the structure of time series and letter sequences generated by nonlinear maps, data series from meteorology, astrophysics, cardiology, cognitive psychology and finance is investigated. The relation between the complexity and the predictability of informational strings is discussed. The relation between local order and the predictability of time series is investigated.
Y1  - 2002
UR  - http://www.pik-potsdam.de/~kropp/myown/book.html
SN  - 3-540-41324-3
ER  - 
TY  - JOUR
A1  - Zaikin, Alexei A.
A1  - García-Ojalvo, Jordi
A1  - Schimansky-Geier, Lutz
A1  - Kurths, Jürgen
T1  - Noise induced propagation in monostable media
N2  - We show that external fluctuations are able to induce propagation of harmonic signals through monostable media. This property is based on the phenomenon of doubly stochastic resonance, where the joint action of multiplicative noise and spatial coupling induces bistability in an otherwise monostable extended medium, and additive noise resonantly enhances the response of the system to a harmonic forcing. Under these conditions, propagation of the harmonic signal through the unforced medium i observed for optimal intensities of the two noises. This noise-induced propagation is studied and quantified in a simple model of coupled nonlinear electronic circuits.
Y1  - 2002
UR  - http://link.aps.org/abstract/PRL/v88/e010601
ER  - 
TY  - JOUR
A1  - Sitz, Andre
A1  - Schwarz, Udo
A1  - Kurths, Jürgen
A1  - Voss, Henning U.
T1  - Estimation of parameters and unobserved components for nonlinear systems from noisy time series
N2  - We study the problem of simultaneous estimation of parameters and unobserved states from noisy data of nonlinear time-continuous systems, including the case of additive stochastic forcing. We propose a solution by adapting the recently developed statistical method of unscented Kalman filtering to this problem. Due to its recursive and derivative-free structure, this method minimizes the cost function in a computationally efficient and robust way. It is found that parameters as well as unobserved components can be estimated with high accuracy, including confidence bands, from heavily noise-corrupted data.
Y1  - 2002
UR  - http://pre.aps.org/
ER  - 
TY  - JOUR
A1  - Zhou, Changsong
A1  - Kurths, Jürgen
A1  - Kiss, Istvan Z.
A1  - Hudson, J. L.
T1  - Noise-enhanced phase synchronization of chaotic oscillators
Y1  - 2002
ER  - 
TY  - JOUR
A1  - Zhou, Changsong
A1  - Kurths, Jürgen
T1  - Noise-induced phase synchronization and synchronization transitions in chaotic oscillators
Y1  - 2002
ER  - 
TY  - JOUR
A1  - Boccaletti, Stefano
A1  - Kurths, Jürgen
A1  - Osipov, Grigory V.
T1  - The synchronization of chaotic systems
Y1  - 2002
ER  - 
TY  - JOUR
A1  - Tokuda, I.
A1  - Kurths, Jürgen
A1  - Rosa, Epaminondas
T1  - Learning phase synchronization from nonsynchronized chaotic regimes
Y1  - 2002
ER  - 
TY  - JOUR
A1  - Osipov, Grigory V.
A1  - Kurths, Jürgen
T1  - Regular and chaotic phase synchronization of coupled circle maps
Y1  - 2002
ER  - 
TY  - JOUR
A1  - Sitz, Andre
A1  - Schwarz, Udo
A1  - Kurths, Jürgen
A1  - Maus, Doris
A1  - Wiese, Michael
A1  - Warnecke, Günter
T1  - Signatures of acoustic emission signals generated during high speed cutting
N2  - Acoustic emission signals generated during high speed cutting of steel are investigated. The data are represen ted in time-folded form. Several methods from linear and nonlinear data analysis based on time- and frequency- domain are applied to the data and reveal signatures of the observed acoustic emission signal. These investiga tions are necessary for modeling the cutting process by means of differential equations.
Y1  - 2001
UR  - http://www.agnld.uni-potsdam.de/~shw/Paper/21618.pdf
ER  - 
TY  - JOUR
A1  - Thiel, Marco
A1  - Romano, Maria Carmen
A1  - Schwarz, Udo
A1  - Kurths, Jürgen
A1  - Hasinger, Günther
A1  - Belloni, Tomaso
T1  - Nonlinear Time series analysis of the X-ray flux of compact objects
N2  - We analyse the X-ray light curves of compact objects using linear and nonlinear time series analysis methods. A Power Density Spectrum (PDS) describes the overall second order properties of the observed data well. To look beyond we propose the nonlinear Q-statistic to detect an asymmetry of the time series. This allows us to find relevant time scales. This method even grants a subclassification of the known states of X-ray sources.
Y1  - 2001
SN  - 0004-640x
ER  - 
TY  - JOUR
A1  - Marwan, Norbert
A1  - Nowaczyk, Norbert R.
A1  - Kurths, Jürgen
A1  - Thiel, Marco
T1  - Cross recurrence plot based rescaling of geological time series
N2  - The rescaling of geological data series to a geological reference time series is of major interest in many investigations. For example, geophysical borehole data should be correlated to a given data series whose time scale is known in order to achieve an age-depth function or the sedimentation rate for the borehole data. Usually this synchronization is performed visually and by hand. Instead of using this wiggle matching by eye, we present the application of cross recurrence plots for such tasks. Using this method, the synchronization and rescaling of geological data to a given time scale is much easier and faster than by hand.
Y1  - 2001
SN  - 1029-7006
ER  - 
TY  - JOUR
A1  - Kurths, Jürgen
A1  - Schwarz, Udo
T1  - Nichtlineare Wissenschaften - neue Paradigmen und Konzepte
N2  - In den letzten 2 Jahrzehnten des 20. Jahrhunderts hat sich mit der rasanten Entwicklung der Nichtlinearen Wissenschaften ein weiterer Umbruch vollzogen, der eine ausgepraegte Nachhaltigkeit in Wissenschaft und Technik ebenso wie in der Gesellschaft erwarten laesst. Die Nichtlinearen Wissenschaften werden auch als Nichtlineare Dynamik, Wissenschaft Komplexer Systeme oder etwas eingegrenzt Chaostheorie bezeichnet.
Y1  - 2001
UR  - http://www.agnld.uni-potsdam.de/~shw/Paper/2001ArtChaos.pdf
SN  - 0177- 3674
ER  - 
TY  - JOUR
A1  - Marwan, Norbert
A1  - Kurths, Jürgen
T1  - Nonlinear analysis of bivariate data with cross recurrence plots
N2  - We use the extension of the method of recurrence plots to cross recurrence plots (CRP) which enables a nonlinear analysis of bivariate data. To quantify CRPs, we develop further three measures of complexity mainly basing on diagonal structures in CRPs. The CRP analysis of prototypical model systems with nonlinear interactions demonstrates that this technique enables to find these nonlinear interrelations from bivariate time series, whereas linear correlation tests do not. Applying the CRP analysis to climatological data, we find a complex relationship between rainfall and El Nino data.
Y1  - 2001
UR  - http://arxiv.org/abs/physics/0201061
ER  - 
TY  - JOUR
A1  - Zaikin, Alexei A.
A1  - Murali, K.
A1  - Kurths, Jürgen
T1  - Simple electronic circuit model for doubly stochastic resonance
N2  - We have recently reported the phenomenon of doubly stochastic resonance [Phys. Rev. Lett. 85, 227 (2000)], a synthesis of noise-induced transition and stochastic resonance. The essential feature of this phenomenon is that multiplicative noise induces a bimodality and additive noise causes stochastic resonance behavior in the induced structure. In the present paper we outline possible applications of this effect and design a simple lattice of electronic circuits for the experimental realization of doubly stochastic resonance.
Y1  - 2001
UR  - http://link.aps.org/abstract/PRE/v63/e020103
ER  - 
TY  - JOUR
A1  - Zaikin, Alexei A.
A1  - Kurths, Jürgen
T1  - Additive noise in noise-induced nonequilibrium transitions
Y1  - 2001
SN  - 1054-1500
ER  - 
TY  - JOUR
A1  - Hassan, M. K.
A1  - Kurths, Jürgen
T1  - Transition from random to ordered fractals in fragmentation of particles in an open system
Y1  - 2001
ER  - 
TY  - BOOK
A1  - Pikovskij, Arkadij
A1  - Rosenblum, Michael
A1  - Kurths, Jürgen
T1  - Synchronization : a universal concept in nonlinear sciences
T3  - Cambridge nonlinear science series
Y1  - 2001
SN  - 0-521-59285-2
VL  - 12
PB  - Cambridge Univ. Press
CY  - Cambridge
ET  - 1st paperback ed., repr
ER  - 
TY  - JOUR
A1  - Zaikin, Alexei A.
A1  - Kurths, Jürgen
T1  - Additive noise and noise-induced nonequilibrium phase transitions
Y1  - 2000
SN  - 1-563-96826-6
ER  - 
TY  - JOUR
A1  - Anishchenko, Vadim S.
A1  - Vadivasova, T. E.
A1  - Kopeikin, A. S.
A1  - Kurths, Jürgen
A1  - Strelkova, G. I.
T1  - Effect of noise on the relaxation to an invariant probability measure of nonhyperbolic chaotic attractors
Y1  - 2001
ER  - 
TY  - JOUR
A1  - Pikovskij, Arkadij
A1  - Rosenblum, Michael
A1  - Kurths, Jürgen
T1  - Phase synchronization in regular and chaotic systems
Y1  - 2000
SN  - 0218-1274
ER  - 
TY  - JOUR
A1  - Zöller, Gert
A1  - Hainzl, Sebastian
A1  - Kurths, Jürgen
T1  - Observation of growing correlation length as an indicator for critical point behavior prior to large earthquakes
Y1  - 2001
ER  - 
TY  - JOUR
A1  - Krampe, Ralf-Thomas
A1  - Engbert, Ralf
A1  - Kliegl, Reinhold
A1  - Kurths, Jürgen
T1  - Koordination und Synchronisation der Hände beim rhythmischen Timing
Y1  - 2000
ER  - 
TY  - JOUR
A1  - Gowin, W.
A1  - Saparin, Peter
A1  - Kurths, Jürgen
T1  - Bone architecture quantification: Measures of complexity compared to failure lead results
Y1  - 2001
ER  - 
TY  - JOUR
A1  - Hassan, M. K.
A1  - Kurths, Jürgen
T1  - Competitive random sequential adsorption of point and fixed-sized particles: analytical results
Y1  - 2001
ER  - 
TY  - JOUR
A1  - Beim Graben, Peter
A1  - Saddy, Douglas
A1  - Schlesewsky, Matthias
A1  - Kurths, Jürgen
T1  - Symbolic dynamics of event-related brain potentials
Y1  - 2000
ER  - 
TY  - JOUR
A1  - Gowin, W.
A1  - Saparin, Peter
A1  - Kurths, Jürgen
A1  - Felsenberg, D.
T1  - Bone Architecture assessment with Measures of Complexity
Y1  - 2001
ER  - 
TY  - JOUR
A1  - Wessel, Niels
A1  - Voss, Andreas
A1  - Malberg, Hagen
A1  - Ziehmann, Christine
A1  - Voss, Henning U.
A1  - Schirdewan, Alexander
A1  - Meyerfeldt, Udo
A1  - Kurths, Jürgen
T1  - Nonlinear analysis of complex phenomena in cardiological data
N2  - The main intention of this contribution is to discuss different nonlinear approaches to heart rate and blood pressure variability analysis for a better understanding of the cardiovascular regulation. We investigate measures of complexity which are based on symbolic dynamics, renormalised entropy and the finite time growth rates. The dual sequence method to estimate the baroreflex sensitivity and the maximal correlation method to estimate the nonlinear coupling between time series are employed for analysing bivariate data. The latter appears to be a suitable method to estimate the strength of the nonlinear coupling and the coupling direction. Heart rate and blood pressure data from clinical pilot studies and from very large clinical studies are analysed. We demonstrate that parameters from nonlinear dynamics are useful for risk stratification after myocardial infarction, for the prediction of life-threatening cardiac events even in short time series, and for modelling the relationship between heart rate and blood pressure regulation. These findings could be of importance for clinical diagnostics, in algorithms for risk stratification, and for therapeutic and preventive tools of next generation implantable cardioverter defibrillators.
Y1  - 2000
ER  - 
TY  - JOUR
A1  - Marwan, Norbert
A1  - Schwarz, Udo
A1  - Kurths, Jürgen
A1  - Strecker, Manfred
T1  - ENSO Impact on landslide generation in northwestern Argentina
N2  - Climatic changes are of major importance in landslide generation in the Argentine Andes. Increased humidity as a potential influential factor was inferred from the temporal clustering of landslide deposits during a period of significantly wetter climate, 30,000 years ago. A change in seasonality was tested by comparing past (inferred from annual-layered lake deposits, 30,000 years old) and modern (present-day observations) precipitation changes. Quantitative analysis of cross recurrence plots were developed to compare the influence of the El Nino/Southern Oscillation (ENSO) on present and past rainfall variations. This analysis has shown the stronger influence of NE trades in the location of landslide deposits in the intra-andean basin and valleys, what caused a higher contrast between summer and winter rainfall and an increasing of precipitation in La Nina years. This is believed to reduce thresholds for landslide generation in the arid to semiarid intra-andean basins and valleys.
Y1  - 2000
SN  - 1029-7006
ER  - 
TY  - JOUR
A1  - Wessel, Niels
A1  - Schumann, Agnes
A1  - Wessel, Niels
A1  - Schumann, Agnes
A1  - Schirdewan, Alexander
A1  - Voss, Andreas
A1  - Kurths, Jürgen
T1  - Entropy measures in heart rate variability data
Y1  - 2000
ER  - 
TY  - JOUR
A1  - Hainzl, Sebastian
A1  - Zöller, Gert
A1  - Kurths, Jürgen
A1  - Zschau, Jochen
T1  - Seismic quiescence as an indicator for large earthquakes in a system of self-organized criticality
Y1  - 2000
ER  - 
TY  - JOUR
A1  - Zaks, Michael A.
A1  - Park, Eun Hyoung
A1  - Kurths, Jürgen
T1  - On phase synchronization by periodic force in chaotic oscillators with saddle equilibria
Y1  - 2000
ER  - 
TY  - JOUR
A1  - Hainzl, Sebastian
A1  - Zöller, Gert
A1  - Kurths, Jürgen
T1  - Self-organization of spatio-temporal earthquake clusters
Y1  - 2000
ER  - 
TY  - JOUR
A1  - Boccaletti, Stefano
A1  - Valladares, D. L.
A1  - Kurths, Jürgen
T1  - Synchronization of chaotic structurally nonequivalent systems
Y1  - 2000
ER  - 
TY  - JOUR
A1  - Ziehmann, Christine
A1  - Smith, Leonard A.
A1  - Kurths, Jürgen
T1  - Localized Lyapunov exponents and the prediction of predictability
Y1  - 2000
ER  - 
TY  - JOUR
A1  - Anishchenko, Vadim S.
A1  - Kopeikin, A. S.
A1  - Kurths, Jürgen
T1  - Studying hyperbolicity in chaotic systems
Y1  - 2000
ER  - 
TY  - JOUR
A1  - Kurths, Jürgen
A1  - Seehafer, Norbert
A1  - Spahn, Frank
T1  - Nichtlineare Dynamik in der Physik : Forschungsbeispiele und Forschungstrends
Y1  - 1999
UR  - http://www.phil.uni-augsburg.de/dgksnd
SN  - 3-540-65329- 5
ER  - 
TY  - JOUR
A1  - Marwan, Norbert
A1  - Trauth, Martin H.
A1  - Schwarz, Udo
A1  - Kurths, Jürgen
A1  - Strecker, Manfred
T1  - Climate dynamics of varved pleistocene lake sediments in nw Argentina
Y1  - 1999
SN  - 1029-7006
ER  - 
TY  - JOUR
A1  - Hainzl, Sebastian
A1  - Zöller, Gert
A1  - Kurths, Jürgen
T1  - Self-organized criticality model for earthquakes : Quiescence, foreshocks and aftershocks
Y1  - 1999
ER  - 
TY  - JOUR
A1  - Pikovskij, Arkadij
A1  - Rosenblum, Michael
A1  - Zaks, Michael A.
A1  - Kurths, Jürgen
T1  - Phase synchronization of regular and chaotic oscillators
Y1  - 1999
ER  - 
TY  - JOUR
A1  - Hainzl, Sebastian
A1  - Zöller, Gert
A1  - Kurths, Jürgen
T1  - Similar power laws for foreshock and aftershock sequences in a spring block model for earthquakes
Y1  - 1999
ER  - 
TY  - JOUR
A1  - Zaks, Michael A.
A1  - Pikovskij, Arkadij
A1  - Kurths, Jürgen
T1  - On the generalized dimensions for the fourier spectrum of the thue-morse sequence
Y1  - 1999
ER  - 
TY  - JOUR
A1  - Voss, Henning U.
A1  - Kurths, Jürgen
T1  - Reconstruction of nonlinear time-delayed feedback models from optical data
Y1  - 1999
ER  - 
TY  - JOUR
A1  - Park, Eun Hyoung
A1  - Zaks, Michael A.
A1  - Kurths, Jürgen
T1  - Phase synchronization in the forced lorenz system
Y1  - 1999
ER  - 
TY  - JOUR
A1  - Lai, Ying Cheng
A1  - Grebogi, Celso
A1  - Kurths, Jürgen
T1  - Modeling of deterministic chaotic systems
Y1  - 1999
ER  - 
TY  - JOUR
A1  - Zaikin, Alexei A.
A1  - Kurths, Jürgen
T1  - Modeling Cognitive Control in Simple Movements
Y1  - 1999
SN  - 1-563-96863-0
ER  - 
TY  - JOUR
A1  - Kolodner, P.
A1  - Abel, Markus
A1  - Kurths, Jürgen
A1  - Voss, Henning U.
T1  - Amplitude equations from spatiotemporal binary-fluid convection data
Y1  - 1999
UR  - http://www.stat.physik.uni-potsdam.de/~markus/papers/PRL83-3422.pdf
ER  - 
TY  - JOUR
A1  - Rosenblum, Michael
A1  - Kurths, Jürgen
A1  - Pikovskij, Arkadij
A1  - Schafer, C.
A1  - Tass, Peter
A1  - Abel, Hans-Henning
T1  - Synchronization in Noisy Systems and Cardiorespiratory Interaction
Y1  - 1998
ER  - 
TY  - JOUR
A1  - Heuer, Axel
A1  - Schultheiss, J.
A1  - Hodgson, N.
A1  - Kurths, Jürgen
A1  - Menzel, Ralf
A1  - Raab, Volker
T1  - Transverse effects in phase conjugate laser mirrors based on stimulated brillouin scattering
Y1  - 1999
ER  - 
TY  - JOUR
A1  - Schwache, A.
A1  - Kurths, Jürgen
A1  - Mitschke, F.
A1  - Voss, Henning U.
T1  - Equations of motion from chaotic data : a driven optical fiber ring resonator
Y1  - 1999
ER  - 
TY  - JOUR
A1  - Rosenblum, Michael
A1  - Abel, Hans-Henning
A1  - Kurths, Jürgen
A1  - Schäfer, Carsten
T1  - Synchronization in the human cardiorespiratory system
Y1  - 1999
ER  - 
TY  - JOUR
A1  - Schwarz, Udo
A1  - Spahn, Frank
A1  - Grebogi, Celso
A1  - Kurths, Jürgen
A1  - Petzschmann, Olaf
T1  - Length scales of clustering in granular gases
Y1  - 1999
ER  - 
TY  - JOUR
A1  - Park, Eun Hyoung
A1  - Rosenblum, Michael
A1  - Kurths, Jürgen
A1  - Zaks, Michael A.
T1  - Alternating locking ratios in imperfect phase synchronization
Y1  - 1999
ER  - 
TY  - JOUR
A1  - Braun, Robert
A1  - Feudel, Fred
A1  - Gebogi, C.
A1  - Kurths, Jürgen
A1  - Witt, Annette
T1  - Tracer dynamics in a flow of driven vortices
Y1  - 1999
ER  - 
TY  - JOUR
A1  - Rosenblum, Michael
A1  - Pikovskij, Arkadij
A1  - Kurths, Jürgen
T1  - From Phase to Lag Synchronization in Coupled Chaotic Oscillators
N2  - We study synchronization transitions in a system of two coupled self-sustained chaotic oscillators. We demonstrate that with the increase of coupling strength the system first undergoes the transition to phase synchronization. With a further increase of coupling, a new synchronous regime is observed, where the states of two oscillators are nearly identical, but one system lags in time to the other. We describe thisregime as a state with correlated amplitudes and a constant phase shift. These transitions are traced in the Lyapunov spectrum.
Y1  - 1997
ER  - 
TY  - JOUR
A1  - Pikovskij, Arkadij
A1  - Kurths, Jürgen
T1  - Coherence Resonance in a Noise-Driven Excitable System
N2  - We study the dynamics of the excitable Fitz Hugh-Nagumo system under external noisy driving. Noise activates the system producing a sequence of pulses. The coherence of these noise-induced oscillations is shown to be maximal for a certain noise amplitude. This new effect of coherence resonance is explained by different noise dependencies of the activation and the excursion times. A simple one-dimensional model based on the Langevin dynamics is proposed for the quantitative description of this phenomenon.
Y1  - 1997
ER  -