Physical Activity Intervention for Leisure-Time Activity Levels Among Older Adults: A Cluster Randomized Trial.

Importance: Current randomized trial evidence of the effects of physical activity interventions in older adults is mainly from developed countries, with little reliable evidence from low- and middle-income countries, such as China, where race, culture, and lifestyles differ substantially from those in Western populations. Objective: To evaluate the effects of a multilevel intervention for increasing leisure-time activity levels in Chinese older adults. Design, Setting, and Participants: This cluster randomized trial was conducted from May 2021 to May 2023, including an 8-week intervention period and a follow-up period of 24 months. Eight villages in China were randomly assigned to the intervention (4 villages) or the control (4 villages) group. Potentially eligible participants were 60 years or older. A total of 511 older adults from the selected 8 villages were enrolled. Interventions: The intervention group received an 8-week socioecological model-based intervention, comprising individual, interpersonal, and community-level components, whereas the control group did not. Main Outcome and Measure: The primary outcome was the change in leisure-time activity at 8 weeks, measured by the Physical Activity Scale for the Elderly (PASE). Possible PASE scores for leisure-time activity range from 0 to 502, with higher scores indicating higher activity levels. Results: A total of 511 older adults from 8 villages were recruited and randomly allocated to the intervention (240 participants, 4 villages) or control (271 participants, 4 villages) groups. The mean (SD) age was 70.95 (5.72) years, and 284 (55.6%) were female participants. Seven serious adverse events (unrelated deaths) were reported. Participants in the intervention group increased leisure-time activity more than those in the control group, with a mean difference in PASE scores of 13.74 points (95% CI, 8.58-18.91 points) between the groups at 8 weeks (P < .001). Significant differences in leisure-time activity were also found over 24 months (mean difference in scores at 4 weeks, 11.66 points; 95% CI, 6.41-16.90 points; P < .001; at 6 months, 12.35 points; 95% CI, 7.19-17.50 points; P < .001; at 12 months, 11.55 points; 95% CI, 6.32-16.78 points; P < .001; and at 24 months, 14.51 points; 95% CI, 9.28-19.75 points; P < .001). Conclusions and Relevance: In this cluster randomized trial, the multilevel intervention was effective in promoting leisure-time activity over 24 months of follow-up in older adults from China. This finding suggests that implementation of such interventions could be an important step in addressing physical inactivity in older adults in low- and middle-income countries. Trial Registration: Chinese Clinical Trial Registry Identifier: ChiCTR2100045653.

Real-time monitoring of the sucrose hydrolysis process based on two-photon coincidence measurements.

Real-time measurement of the biochemical reaction process has important application scenarios. Due to the chirality of a large number of life-sustaining molecules, many parameters of the reaction kinetics involving these chiral molecules, such as the reaction rate and the reagents concentrations, could be tracked by monitoring the optical activity of the substrate and/or product molecules. However, the optical activity of photosensitive biomolecules does not allow traditional laser-based real-time measurement due to the vulnerability of their biochemical properties under high-intensity light regimes. Here we introduce a real-time tracking technique of the sucrose hydrolysis reaction based on two-photon coincidence measurements. The two-photon source is generated based on a spontaneous parametric down-conversion process. During the reaction, the kinetic parameters are obtained by the real-time measurement of the change of the polarization of the photons when operating at extremely low-light regimes. Compared with single-photon counting measurements, two-photon coincidence measurements have higher signal-to-noise ratios and better robustness, which demonstrates the potential value in monitoring the photosensitive biochemical reaction processes.

Wavelength-switchable ultra-narrow linewidth fiber laser enabled by a figure-8 compound-ring-cavity filter and a polarization-managed four-channel filter.

We propose and demonstrate a high-performance wavelength-switchable erbium-doped fiber laser (EDFL), enabled by a figure-8 compound-ring-cavity (F8-CRC) filter for single-longitudinal-mode (SLM) selection and a polarization-managed four-channel filter (PM-FCF) for defining four lasing wavelengths. We introduce a novel methodology utilizing signal-flow graph combined with Mason's rule to analyze a CRC filter in general and apply it to obtain the important design parameters for the F8-CRC used in this paper. By combining the functions of the F8-CRC filter and the PM-FCF assisted by the enhanced polarization hole-burning and polarization dependent loss, we achieve the EDFL with fifteen lasing states, including four single-, six dual-, four tri- and one quad-wavelength lasing operations. In particular, all the four single-wavelength operations are in stable SLM oscillation, typically with a linewidth of <600 Hz, a RIN of ≤-154.58 dB/Hz@≥3 MHz and an output power fluctuation of ≤±3.45%. In addition, all the six dual-wavelength operations have very similar performances, with the performance parameters close to those of the four single-wavelength operations, superior to our previous work and others' similar work significantly. Finally, we achieve the wavelength-spacing tuning of dual-wavelength operations for photonic generation of tunable microwave signals, and successfully obtain a signal at 23.10 GHz as a demonstration.

Four-wavelength-switchable SLM fiber laser with sub-kHz linewidth using superimposed high-birefringence FBG and dual-coupler ring based compound-cavity filter.

We propose and demonstrate a four-wavelength-switchable erbium-doped fiber laser (4WS-EDFL) with a four-channel superimposed high-birefringence fiber Bragg grating (SI-HBFBG) and a dual-coupler ring based compound-cavity (DCR-CC) filter. Both for the first time, a SI-HBFBG as a four-channel reflective filter is used in a multi-wavelength switchable fiber laser to define wavelength channels and a DCR-CC filter is used to select a single mode from dense longitudinal-modes in a fiber laser. We present in detail how to design, fabricate, and characterize the DCR-CC filter with both theoretical analysis and experimental results, which we believe is the first systematic approach for making a compound-cavity based filter used for selecting single-longitudinal mode (SLM) in a fiber laser. The enhanced polarization hole burning effect in a 2.9 m long erbium-doped fiber, coiled inside a three-loop polarization controller, and the polarization-mismatch-induced losses are introduced into the laser cavity to achieve wavelength-switching operations. We show that the 4WS-EDFL can be switched among fifteen lasing states, including four single-wavelength operations, six dual-wavelength operations, four three-wavelength operations and one four-wavelength operation, all with high stability. For demonstration, in switchable single-wavelength operations, the four SLM lasing outputs measured are all with an optical signal to noise ratio of >80 dB, a linewidth of <700 Hz, a relative intensity noise of ≤-156.7 dB/Hz at frequencies over 3 MHz, an output power fluctuation of ≤0.555 dB and excellent polarization characteristics.