The worldwide rise of skin cancer incidence rates increases the need to investigate ultraviolet radiation (UVR), as it is one of the main causes of skin cancer. 1 A ’ u to UVR varies depending on different factors such as the location of the individual and shielding effects. In this analysis, we evaluated wearables at different body positions measuring ultraviolet radiation when worn during daily activities at different locations. First, we analyzed which of the body positions provide the most robust measurements. We then devised a new measure, the horizon shielding factor, to evaluate the effect of horizon shielding and explored if high/low horizon shielding factor values coincide with particular geospatial attributes.
Exergames provide a challenging opportunity for home-based training and evaluation of postural control in the elderly population, but affordable sensor technology and algorithms for assessment of whole body movement patterns in the home environment are yet to be developed. The aim of the present study was to evaluate the use of Kinect, a commonly available video game sensor, for capturing and analyzing whole body movement patterns. Healthy adults (. n=20) played a weight shifting exergame under five different conditions with varying amplitudes and speed of sway movement, while 3D positions of ten body segments were recorded in the frontal plane using Kinect and a Vicon 3D camera system. Principal Component Analysis (PCA) was used to extract and compare movement patterns and the variance in individual body segment positions explained by these patterns. Using the identified patterns, balance outcome measures based on spatiotemporal sway characteristics were computed. The results showed that both Vicon and Kinect capture >90% variance of all body segment movements within three PCs. Kinect-derived movement patterns were found to explain variance in trunk movements accurately, yet explained variance in hand and foot segments was underestimated and overestimated respectively by as much as 30%. Differences between both systems with respect to balance outcome measures range 0.3-64.3%. The results imply that Kinect provides the unique possibility of quantifying balance ability while performing complex tasks in an exergame environment.
RationaleIn bioelectrical impedance analysis (BIA) measurements, one pair of electrodes is typically placed dorsal on the right hand (position A) and one pair on the foot. In patients with fragile skin, scars or wounds, this dorsal hand placement is not always possible. This study compares agreement of BIA measurements at seven alternative placements with position A. MethodsBIA measurements were performed with the Bodystat-500 using eight combinations of hand electrodes: at the dorsal side of the hand (position A) or dorsal side hand-forearm (position B and C); at the palmar side of the hand (position D) or palmar side hand-forearm (position E and F) or mixed palmar-dorsal side of the hand (position G and H). ICCs were used to compare alle outcomes to position A. Changes in fat mass ∆FM, fat-free mass ∆FFM and appendicular skeletal muscle mass ∆ASMM were calculated using Kyle’s formula.ResultsSeventy healthy Caucasian participants were measured: median age 22 years, IQR 21-23; mean BMI 22.8 ± 2.5 kg/m². Electrode positions D,G and H showed an ICC 0.99-1.00 for ∆FM, ∆FFM and ∆ASMM with minimal changes in ∆FFM and ∆FM: 0.1–0.4 kg ± 0.3 kg and ∆ASMM: 0.0–0.2 kg ± 0.2 kg. Measurements at position B, C, E, and F showed significant and clinically relevant differences with ∆FM and ∆FFM: 3.8–4.0 kg ± 1.1 kg and ∆ASMM: 2.0–2.1 kg ± 0.6 kg, with ICCs 0.96-0.97.ConclusionAlternatively to the typical electrode placement on the dorsal side of the hand, this study demonstrates that three alternative placements results in an excellent agreement with only minimal changes in FFM, FM and ASMM. In practice, placing electrodes at more proximal positions on the forearm should be avoided. Alternatively, we recommend a mixed or palmar electrode placement on the hand.
