Browsing by Autor "Niels Wessel"

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Classification of cardiovascular time series based on different coupling structures using recurrence networks analysis
(Royal Society, 2013) Gonzalo Marcelo Ramírez-Ávila; A. Gapelyuk; Norbert Marwan; Thomas Walther; Holger Stepan; Jürgen Kurths; Niels Wessel
We analyse cardiovascular time series with the aim of performing early prediction of preeclampsia (PE), a pregnancy-specific disorder causing maternal and foetal morbidity and mortality. The analysis is made using a novel approach, namely the ε -recurrence networks applied to a phase space constructed by means of the time series of the variabilities of the heart rate and the blood pressure (systolic and diastolic). All the possible coupling structures among these variables are considered for the analysis. Network measures such as average path length, mean coreness, global clustering coefficient and scale-local transitivity dimension are computed and constitute the parameters for the subsequent quadratic discriminant analysis. This allows us to predict PE with a sensitivity of 91.7 per cent and a specificity of 68.1 per cent, thus validating the use of this method for classifying healthy and preeclamptic patients.
Classifying healthy women and preeclamptic patients from cardiovascular data using recurrence and complex network methods
(Elsevier BV, 2013) Gonzalo Marcelo Ramírez-Ávila; A. Gapelyuk; Norbert Marwan; Holger Stepan; Jürgen Kurths; Thomas Walther; Niels Wessel
Firefly courtship as the basis of the synchronization-response principle
(Institute of Physics, 2011) Gonzalo Marcelo Ramírez-Ávila; J. L. Deneubourg; Jean‐Luc Guisset; Niels Wessel; Jürgen Kurths
Response to synchronization seems to be a widespread phenomenon specially in biological systems. We highlight this phenomenon studying the courtship of flashing fireflies in which a typical collective rhythm occurring only among the males arises and it is followed by a response of the females. Based on a model issued from electronic fireflies, we explain the synchronization of the males and the active responses of the females in the courtship of mingled (both sexes) populations of fireflies. The model also explains the courtship behavior of other species whose interactions follow the same logic even if their physical features are different. Moreover, the model can make predictions on the behavior of mingled and mixed (natural and artificial) groups of such animals. This finding could be considered as the basis of a new principle, namely the synchronization-response. © Europhysics Letters Association, 2011.