Correlation of fatigue with disability and accelerometer-measured daily physical activity in patients with relapsing-remitting MS.

BACKGROUND: Fatigue is one of the most common symptoms in patients with multiple sclerosis (MS). Furthermore, measuring its effects on patients in daily life is challenging. This study aimed to discover the association between relapsing-remitting MS (RRMS) patients' disability, fatigue, and accelerometer-measured physical activity. METHODS: A total of 41 patients with RRMS with an Expanded Disability Status Scale (EDSS) level of 0-5.5 and 20 healthy controls completed the Modified Fatigue Impact Scale (MFIS) and the Fatigue Severity Scale (FSS) questionnaires. The EDSS was evaluated for all patients with RRMS, and all participants performed the MS Functional Composite (MSFC) test and six-min walk test and wore an accelerometer for seven days. RESULTS: Patients with an EDSS level of 0-2.5 were found to have higher fatigue levels (p < 0.001) than healthy controls but lower levels than patients with an EDSS level of 3-5.5 (p < 0.001). A significant correlation was found to exist between fatigue and disability level measured by the EDSS (EDSS/FSS, r=0.750/p=0.001; EDSS/MFIS, r=0.661/p=0.001) and with the MSFC test in the patient group (MSFC/FSS, r = -0.350 p=0.025; MSFC/MFIS, r = -0.423/p=0.007). Total daily activity correlated with fatigue as measured by the FSS (MVPS/FSS r = -0.357/p=0.028, step count/FSS r = -0.463/p=0.003), but no correlation was found between the EDSS or the MSFC. CONCLUSION: A lower disability rate, better physical condition, and higher daily-living activity were found to predict lower fatigue levels.

Harmonics as an alternative method for measuring I0 during x-ray absorption spectroscopy experiments at laboratory scale.

In the recent years, the advent of an efficient and compact laboratory-scale spectrometer for x-ray absorption spectroscopy experiments has been extensively reported in the literature. Such modern instruments offer the advantage to routinely use x-ray absorption spectroscopy on systematic studies, which is usually unconceivable at synchrotron radiation source facilities due to often limited time access. However, one limiting factor is the fact that due to laboratory x-ray source brightness compared to a synchrotron, two separate measures of the incoming and transmitted x-ray intensities, i.e., the so-called I0 and I1, respectively, are usually required. Herein, we introduce and discuss an alternative approach for measuring I0 and I1 simultaneously. Based on the usage of harmonics arising naturally from the use of monochromator crystals, the reliability and robustness of our proposed approach is demonstrated through experiments at the Co K-edge measured using Co metal foil and at the Nd L3-edge measured in Nd2O3.