TY - JOUR A1 - Bergner, Andre A1 - Frasca, M. A1 - Sciuto, G. A1 - Buscarino, A. A1 - Ngamga, Eulalie Joelle A1 - Fortuna, L. A1 - Kurths, Jürgen T1 - Remote synchronization in star networks JF - Physical review : E, Statistical, nonlinear and soft matter physics N2 - We study phase synchronization in a network motif with a starlike structure in which the central node's (the hub's) frequency is strongly detuned against the other peripheral nodes. We find numerically and experimentally a regime of remote synchronization (RS), where the peripheral nodes form a phase synchronized cluster, while the hub remains free with its own dynamics and serves just as a transmitter for the other nodes. We explain the mechanism for this RS by the existence of a free amplitude and also show that systems with a fixed or constant amplitude, such as the classic Kuramoto phase oscillator, are not able to generate this phenomenon. Further, we derive an analytic expression which supports our explanation of the mechanism. Y1 - 2012 U6 - https://doi.org/10.1103/PhysRevE.85.026208 SN - 1539-3755 VL - 85 IS - 2 PB - American Physical Society CY - College Park ER - TY - JOUR A1 - Rusconi, Marco A1 - Valleriani, Angelo A1 - Dunlop, John William Chapman A1 - Kurths, Jürgen A1 - Weinkamer, Richard T1 - Quantitative approach to the stochastics of bone remodeling JF - epl : a letters journal exploring the frontiers of physics N2 - During life bones constantly adapt their structure to their mechanical environment via a mechanically controlled process called bone remodeling. For trabecular bone, this process modifies the thickness of each trabecula leading occasionally to full resorption. We describe the irreversible dynamics of the trabecular thickness distribution (TTD) by means of a Markov chain discrete in space and time. By using thickness data from adult patients, we derive the transition probabilities in the chain. This allows a quantification, in terms of geometrical quantities, of the control of bone remodeling and thus to determine the evolution of the TTD with age. Y1 - 2012 U6 - https://doi.org/10.1209/0295-5075/97/28009 SN - 0295-5075 VL - 97 IS - 2 PB - EDP Sciences CY - Mulhouse ER - TY - JOUR A1 - Marwan, Norbert A1 - Beller, Gise A1 - Felsenberg, Dieter A1 - Saparin, Peter A1 - Kurths, Jürgen T1 - quantifying changes in the spatial structure of trabecular bone JF - International journal of bifurcation and chaos : in applied sciences and engineering N2 - We apply recently introduced measures of complexity for the structural quantification of distal tibial bone. For the first time, we are able to investigate the temporal structural alteration of trabecular bone. Based on four patients, we show how the bone may alter due to temporal immobilization. KW - 3D medical image analysis KW - pQCT KW - trabecular bone KW - patient immobilization Y1 - 2012 U6 - https://doi.org/10.1142/S0218127412500277 SN - 0218-1274 VL - 22 IS - 2 PB - World Scientific CY - Singapore ER - TY - JOUR A1 - Malik, Nishant A1 - Zou, Y. A1 - Marwan, Norbert A1 - Kurths, Jürgen T1 - Dynamical regimes and transitions in plio-pleistocene Asian monsoon JF - epl : a letters journal exploring the frontiers of physics N2 - We propose a novel approach based on the fluctuation of similarity to identify regimes of distinct dynamical complexity in short time series. A statistical test is developed to estimate the significance of the identified transitions. Our method is verified by uncovering bifurcation structures in several paradigmatic models, providing more complex transitions compared with traditional Lyapunov exponents. In a real-world situation, we apply this method to identify millennial-scale dynamical transitions in Plio-Pleistocene proxy records of the South Asian summer monsoon system. We infer that many of these transitions are induced by the external forcing of the solar insolation and are also affected by internal forcing on Monsoonal dynamics, i.e., the glaciation cycles of the Northern Hemisphere and the onset of the Walker circulation. Y1 - 2012 U6 - https://doi.org/10.1209/0295-5075/97/40009 SN - 0295-5075 VL - 97 IS - 4 PB - EDP Sciences CY - Mulhouse 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 - Frasca, Mattia A1 - Bergner, Andre A1 - Kurths, Jürgen A1 - Fortuna, Luigi T1 - Bifurcations in a star-like network of Stuart-Landau oscillators JF - International journal of bifurcation and chaos : in applied sciences and engineering N2 - In this paper, we analytically study a star motif of Stuart-Landau oscillators, derive the bifurcation diagram and discuss the different forms of synchronization arising in such a system. Despite the parameter mismatch between the central node and the peripheral ones, an analytical approach independent of the number of units in the system has been proposed. The approach allows to calculate the separatrices between the regions with distinct dynamical behavior and to determine the nature of the different transitions to synchronization appearing in the system. The theoretical analysis is supported by numerical results. KW - Complex networks KW - synchronization KW - bifurcations Y1 - 2012 U6 - https://doi.org/10.1142/S0218127412501738 SN - 0218-1274 VL - 22 IS - 7 PB - World Scientific CY - Singapore ER - TY - JOUR A1 - Srinivasan, K. A1 - Senthilkumar, D. V. A1 - Mohamed, I. Raja A1 - Murali, K. A1 - Lakshmanan, M. A1 - Kurths, Jürgen T1 - Anticipating, complete and lag synchronizations in RC phase-shift network based coupled Chua's circuits without delay JF - Chaos : an interdisciplinary journal of nonlinear science N2 - We construct a new RC phase shift network based Chua's circuit, which exhibits a period-doubling bifurcation route to chaos. Using coupled versions of such a phase-shift network based Chua's oscillators, we describe a new method for achieving complete synchronization (CS), approximate lag synchronization (LS), and approximate anticipating synchronization (AS) without delay or parameter mismatch. Employing the Pecora and Carroll approach, chaos synchronization is achieved in coupled chaotic oscillators, where the drive system variables control the response system. As a result, AS or LS or CS is demonstrated without using a variable delay line both experimentally and numerically. Y1 - 2012 U6 - https://doi.org/10.1063/1.4711375 SN - 1054-1500 VL - 22 IS - 2 PB - American Institute of Physics CY - Melville ER - TY - JOUR A1 - Malik, Nishant A1 - Bookhagen, Bodo A1 - Marwan, Norbert A1 - Kurths, Jürgen T1 - Analysis of spatial and temporal extreme monsoonal rainfall over South Asia using complex networks JF - Climate dynamics : observational, theoretical and computational research on the climate system N2 - We present a detailed analysis of summer monsoon rainfall over the Indian peninsular using nonlinear spatial correlations. This analysis is carried out employing the tools of complex networks and a measure of nonlinear correlation for point processes such as rainfall, called event synchronization. This study provides valuable insights into the spatial organization, scales, and structure of the 90th and 94th percentile rainfall events during the Indian summer monsoon (June-September). We furthermore analyse the influence of different critical synoptic atmospheric systems and the impact of the steep Himalayan topography on rainfall patterns. The presented method not only helps us in visualising the structure of the extreme-event rainfall fields, but also identifies the water vapor pathways and decadal-scale moisture sinks over the region. Furthermore a simple scheme based on complex networks is presented to decipher the spatial intricacies and temporal evolution of monsoonal rainfall patterns over the last 6 decades. KW - Indian summer monsoon KW - Event synchronization KW - Complex networks KW - Rainfall patterns Y1 - 2012 U6 - https://doi.org/10.1007/s00382-011-1156-4 SN - 0930-7575 VL - 39 IS - 3-4 SP - 971 EP - 987 PB - Springer CY - New York ER -