Comparability and feasibility of wrist- and hip-worn accelerometers in free-living adolescents

Objective: To determine the comparability and feasibility of wrist- and hip-worn accelerometers among free-living adolescents. Design: 89 adolescents (age = 13–14 years old) from eight secondary schools in New South Wales (NSW), Australia wore wrist-worn GENEActiv and hip-worn ActiGraph (GT3X+) accelerometers simultaneously for seven days and completed an accelerometry behavior questionnaire. Methods: Bivariate correlations between the wrist- and hip-worn out-put were used to determine concurrent validity. Paired samples t-test were used to compare minutes per day in moderate-to-vigorous physical activity (MVPA). Group means and paired sample t-tests were used to analyze participants’ perceptions of the wrist- and hip-worn monitoring protocols to assist with determining the feasibility. Results: Wrist-worn accelerometry compared favorably with the hip-worn in average activity (r = 0.88, p < 0.001) and MVPA (r = 0.84 p < 0.001, mean difference = 3.54 min/day, SD = 12.37). The wrist-worn accelerometer had 50% fewer non-valid days (75 days, 12%) than the hip-worn accelerometer (n = 152, 24.4%). Participants reported they liked to wear the device on the wrist (p < 0.01), and that it was less uncomfortable (p = 0.02) and less embarrassing to wear on the wrist (p < 0.01). Furthermore, that they would be more willing to wear the device again on the wrist over the hip (p < 0.01). Conclusions: Our findings reveal there is a strong linear relationship between wrist- and hip-worn accelerometer out-put among adolescents in free-living conditions. Adolescent compliance was significantly higher with wrist placement, with participants reporting that it was more comfortable and less embarrassing to wear on the wrist

Excited-State Proton Transfer in <i>syn</i>-2-(2′-Pyridyl)pyrrole Occurs on the Nanosecond Time Scale in the Gas Phase

Microwave and UV excitation spectra of 2-(2′-pyridyl)pyrrole (2PP) have been recorded at high resolution in the gas phase. Analyses of these data show that the <i>syn</i> conformer of 2PP is a planar molecule in both the ground (S₀) and first excited (S₁) electronic states, and that the S₁ state undergoes a relatively slow excited-state proton transfer (ESPT) reaction when excited by light, as measured by the homogeneous line broadening that is observed in its UV spectrum. Apparently, excitation of the S₁ state moves electronic charge from the pyrrole ring to the pyridine ring, but the simultaneous transfer of the proton is inhibited by an unfavorably oriented dipole under solvent-free conditions. The rate of the ESPT reaction is enhanced by more than an order of magnitude with simultaneous excitation of a 144 cm^–1 in-plane vibrational mode