Department of Mathematics, Bernoulli Institute, Faculty of Science and Engineering, University of Groningen, AG Groningen, The Netherlands.|Laboratory of Pediatrics, Section Systems Medicine of Metabolism and Signaling, University of Groningen, University Medical Center Groningen, AV Groningen, The Netherlands.|Laboratory of Pediatrics, Section Systems Medicine of Metabolism and Signaling, University of Groningen, University Medical Center Groningen, AV Groningen, The Netherlands.|Department of Mathematics, Bernoulli Institute, Faculty of Science and Engineering, University of Groningen, AG Groningen, The Netherlands.