BackgroundAlthough walking speed is associated with important clinical outcomes and designated as the sixth vital sign of the elderly, few walking-speed estimation algorithms using an inertial measurement unit (IMU) have been derived and tested in the older adults, especially in the elderly with slow speed. We aimed to develop a walking-speed estimation algorithm for older adults based on an IMU.MethodsWe used data from 659 of 785 elderly enrolled from the cohort study. We measured gait using an IMU attached on the lower back while participants walked around a 28 m long round walkway thrice at comfortable paces. Best-fit linear regression models were developed using selected demographic, anthropometric, and IMU features to estimate the walking speed. The accuracy of the algorithm was verified using mean absolute error (MAE) and root mean square error (RMSE) in an independent validation set. Additionally, we verified concurrent validity with GAITRite using intraclass correlation coefficients (ICCs).ResultsThe proposed algorithm incorporates the age, sex, foot length, vertical displacement, cadence, and step-time variability obtained from an IMU sensor. It exhibited high estimation accuracy for the walking speed of the elderly and remarkable concurrent validity compared to the GAITRite (MAE = 4.70%, RMSE = 6.81 𝑐𝑚/𝑠, concurrent validity (ICC (3,1)) = 0.937). Moreover, it achieved high estimation accuracy even for slow walking by applying a slow-speed-specific regression model sequentially after estimation by a general regression model. The accuracy was higher than those obtained with models based on the human gait model with or without calibration to fit the population.ConclusionsThe developed inertial-sensor-based walking-speed estimation algorithm can accurately estimate the walking speed of older adults.

Platinum-dendrimer hybrid nanowires were prepared by electrochemical reduction of the poly͑amidoamine͒ ͑PAMAM͒ dendrimer-platinum͑IV͒ complexes on carbon electrodes covered with alumina template membranes and characterized using scanning probe microscopy and transmission electron microscopy. Direct electrochemical deposition of the fourth and fifth generation dendrimer coordinated platinum ion complexes resulted in formation of well-defined nanowires. The electrochemical reduction of platinum͑IV͒ complexes with fourth or fifth generation PAMAM dendrimers led to the formation of nanowires, due perhaps to the cross-linking of dendrimer molecules via complex formation of amine groups with platinum͑IV͒, intermolecular interaction between dendrimer branches, and potential induced force between the electrode surface and platinum͑IV͒-dendrimer complexes. The nanosized platinum-dendrimer hybrid nanowires prepared electrochemically on glassy carbon electrodes displayed good catalytic activity for electrochemical reduction of oxygen and oxidation of alcohols.

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