>Methods to study complex systems

related to PIK flagships Time Series Analysis and Complex Networks

Recurrence plots

Recurrence Plot

Recurrence plots (RPs) provide an alternative way to study various aspects of complex systems, such regime transitions, classification, detection of time-scales, synchronisation, and coupling detection (RP bibliography). Main contributions have been in bivariate extensions (cross RPs) and coupling analysis, new measures of complexity, significance assessments of the RP based results, spatial extensions, parameter selection, RPs for irregularly sampled data, or complex network based quantification.

Complex networks

Complex networks provide a powerful approach to investigate extended and spatio-temporal systems, such as the climate by climate networks. Moreover, they offer an alternative way for a recurrence based time-series analysis by recurrence networks.

Special time-series analysis methods for special problems

Absolute Age

Special problems require especially adopted methods of time-series analysis. For example, proxy records in Earth sciences are often irregularly sampled and come with uncertainties in the dating points. Approaches for considering such dating uncertainties in the subsequent analysis and methods for correlation analysis of irregularly sampled time series have been developed. Such approaches can be helpful for the reconstruction of palaeoclimate complex networks.

>Complexity in applications

Climate and palaeoclimate

The study of palaeoclimate from proxy records is helpful for a better understanding of the climate system. Information based on lake sediments or speleothemes can be used to study complex interrelationships or past climate transitions.

Cover Science 2012

Cardiovascular systems

Besides the main focus on climate related problems, recurrence properties of the cardiovascular system are studied, e.g., to early detect ventricular tachycardia or preeclampsia, or to investigate the coupling mechanisms in the cardio-respiratory system.

EEG analysis

Further interest in life science is related to EEG analysis, aiming at the detection of event related potentials or early signatures of epileptic seizures.

3D image analysis

3D microCT image of trabecular bone

Methods to investigate complexity in 3D have been applied to study structural changes in trabecular bone, such as occurring during osteoporosis or space flights.

>Cave research


Scientific research in caves is performed to explore and survey newly discovered cave parts, but also to collect data for the palaeoclimate studies (samples, monitoring). Cave research is focused on caves in Switzerland (research with isaak), but also in India, Caucasus, Kosovo, and Germany.

>Projects & grants