OLEDs as models for bird magnetoception: detecting electron spin resonance in geomagnetic fields.

Certain species of living creatures are known to orientate themselves in the geomagnetic field. Given the small magnitude of approximately 48 µT, the underlying quantum mechanical phenomena are expected to exhibit coherence times in the microsecond regime. In this contribution, we show the sensitivity of organic light-emitting diodes (OLEDs) to magnetic fields far below Earth's magnetic field, suggesting that coherence times of the spins of charge-carrier pairs in these devices can be similarly long. By electron paramagnetic resonance (EPR) experiments, a lower bound for the coherence time can be assessed directly. Moreover, this technique offers the possibility to determine the distribution of hyperfine fields within the organic semiconductor layer. We extend this technique to a material system exhibiting both fluorescence and phosphorescence, demonstrating stable anticorrelation between optically detected magnetic resonance (ODMR) spectra in the singlet (fluorescence) and triplet (phosphorescence) channels. The experiments demonstrate the extreme sensitivity of OLEDs to both static as well as dynamic magnetic fields and suggest that coherent spin precession processes of coulombically bound electron-spin pairs may play a crucial role in the magnetoreceptive ability of living creatures.

Are Repeated Self-Reports of Psychological Variables Feasible for Patients Near the End of Life at a Palliative Care Unit?

BACKGROUND: Patient-reported outcome (PRO) measurement is crucial to assess the benefit of psychotherapeutic interventions. Is repeated assessment of psychometric self-report data possible, as inpatient palliative care patients suffer from physical and psychological symptoms? What is the self-perceived strain caused by the assessment? Objective The main objective of this study was to investigate the feasibility of a repeated comprehensive psychometric self-assessment of inpatient palliative care patients. Secondary objectives were the PROs of the psychometric assessment. DESIGN: We conducted a prospective cohort study. Patients admitted to our palliative care unit (PCU) were reviewed for eligibility within 72 hours. They were asked for weekly self-reports regarding hope (HHI-D), well-being (FACIT-Sp), anxiety and depression (STADI), and quality of life (QoL; EORTC-QLQ-C-30 single item). The strain caused by the assessment was assessed by a numeric rating scale (0-10) and free comments. RESULTS: Within 11 months, 219 patients were admitted to the PCU. In total, 92 patients were eligible. The most frequent exclusion criterion was "life expectancy <1 week." A total of 60 patients participated at the first point of measurement. The mean of self-perceived strain (Likert scale 0-10) due to the assessment was 1.44 (SD 1.99) at T1. Twenty-four patients participated twice. Here we found increased scores for physical well-being and QoL. CONCLUSION: Repeated assessment of psychological conditions is feasible for 27.4% of inpatients at a German PCU. The most limiting factor is life expectancy of only days at admission to the PCU. However, the self-perceived strain is low.