Towards a Real-Time Warning System for Detecting Inaccuracies in Photoplethysmography-Based Heart Rate Measurements in Wearable Devices. - Rania Islmabouli; Marlene Brunner; Devender Kumar; Mahdi Sareban; Gunnar Treff; Michael Neudorfer; Josef Niebauer; Arne Bathke; Jan David Smeddinck (CoRR, 2025)