Na+-doped zinc oxide nanofiber membrane for high speed humidity sensor

A novel sensitive humidity nanosensor based on Na1-doped ZnO nanofiber membrane has been prepared via electrospinning and calcination. The product was characterized by scanning electron microscopy and X-ray diffraction. During the whole relative humidity (11%–95%) measurement, the response and recovery time is about 3 and 6 s, respectively, with good linearity, and reproducibility. These remarkable and sensitive sensing performances make our product a good candidate in fabricating humidity sensors.

Individual calibration for estimating free-living walking speed using the MTI monitor

Purpose : This study was conducted to devise a new individual calibration method to enhance MTI accelerometer estimation of free-living level walking speed.

Method : Five female and five male middle-aged adults walked 400 m at 3.5, 4.5, and 5.5 km·h-1, and 800 m at 6.5 km·h-1 on an outdoor track, following a continuous protocol. Lap speed was controlled by a global positioning system (GPS) monitor. MTI counts-to-speed calibration equations were derived for each trial, for each subject for four such trials with each of four MTI, for each subject for the average MTI, and for the pooled data. Standard errors of the estimate (SEE) with and without individual calibration were compared. To assess accuracy of prediction of free-living walking speed, subjects also completed a self-paced, "brisk" 3-km walk wearing one of the four MTI, and differences between actual and predicted walking speed with and without individual calibration were examined.

Results : Correlations between MTI counts and walking speed were 0.90 without individual calibration, 0.98 with individual calibration for the average MTI, and 0.99 with individual calibration for a specific MTI. The SEE (mean ± SD) was 0.58 ± 0.30 km·h-1 without individual calibration, 0.19 ± 0.09 km·h-1 with individual calibration for the average MTI monitor, and 0.16 ± 0.08 km·h-1 with individual calibration for a specific MTI monitor. The difference between actual and predicted walking speed on the "brisk" 3-km walk was 0.06 ± 0.25 km·h-1 using individual calibration and 0.28 ± 0.63 km·h-1 without individual calibration (for specific accelerometers).

Conclusion : MTI accuracy in predicting walking speed without individual calibration might be sufficient for population-based studies but not for intervention trials. This individual calibration method will substantially increase precision of walking speed predicted from MTI counts.

The volume of water filtered by a Continuous Plankton Recorder sample: the effect of ship speed

The Continuous Plankton Recorder (CPR) survey is one of the largest plankton-monitoring programmes in the world. Since 1931, the CPR has collected ∼380 000 samples, each representing 10 miles of tow. It has been assumed that the volume of seawater filtered by each sample remained constant and close to 3 m3. In this study, the volume filtered for each CPR sample was measured on two routes (SA and IN), monitored by the CPR survey, between 1995 and 2000. Although the filtered volume was near the theoretical value of 3 m3 on the SA route (3.2 m3), it was significantly higher on the IN route (3.8 m3). A significant negative relationship was found between the volume filtered and the speed of the ships. This relationship indicates that the faster the speed of the ship, the lower the volume filtered. This could have implications for the CPR survey as the speed of the ships has increased continuously since the end of the 1950s. However, no significant correlation was found between the long-term changes in the speed of the ships and two commonly used indicators of plankton variability: the Phytoplankton Colour and the Total Copepods indices. This absence of relationship may indicate that the effect found is small in comparison with the influence of hydroclimatic forcing, although a more extensive study is needed to confirm these findings.