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.

Consumer response to unit pricing for mobile telephony

This project is a co-operative study between ACCAN and Deakin University. It focuses on Unit Pricing, the practice of displaying the price of goods or services based on a standard quantity, to allow a direct comparison between competitive offers. This study aimed at gauging whether the new unit pricing information for mobile phone contracts assists consumers in assessing and comparing the value provided across alternative contracts within and between suppliers. Some 24 in-depth interviews were conducted with consumers who had recently bought or renewed a mobile phone contract.
The research showed that most consumers could use unit pricing information and some found it useful. Where consumers’ plans had unlimited or infinite capacity, unit pricing information was not relevant. Many consumers preferred voice allowances to be expressed in minutes, rather than in dollar allowances. Data was the most problematic category, as consumers typically had only limited understanding of the amount of data that various applications used. Most did have a broad understanding of what total capacity in data they would need, typically expressed in gigabytes.
Consumers commonly sought simplicity in deciding on which plan they would purchase or renew. A key issue for consumers was not “going over”, that is not exceeding their call, text or data allowances. For that reason, they were prepared to choose a plan that commonly resulted in them not using their full allowances each month. Some consumers used Apps on their smartphones to monitor their usage. Not all consumers had experienced advisory messages about nearing the limits of their plan’s allowances.
The Report recommended that:

R1. Unit pricing should be maintained
R2. Where unit pricing is provided for call costs, these should be expressed in terms of a one-minute call.
R3 Unit pricing for data should be expressed in terms of gigabytes or part thereof.
R4 In advertising mobile phone plans and at point of sales, customers should be provided with three levels of information – 1) overall plan features, 2) unit pricing information and 3) a data calculator.
R5 Level 2 and 3 information should be provided in a standard format across the industry, enabling consumers to make ready comparisons between plans and between competitive offers from different providers.
R6. Continuing public education is needed.
R7. Warnings about going over should always include the date when the allowance period ends and tell consumers what the rate will be if they “go over” based on the Level 2 information.
R8. The Consumer Protection Code should be reviewed in the light of these findings and recommendations.

Enhancing permanganate chemiluminescence detection for the determination of glutathione and glutathione disulfide in biological matrices

Acidic potassium permanganate chemiluminescence enables direct post-column detection of glutathione, but its application to assess the redox state of a wider range of biological fluids and tissues is limited by its sensitivity. Herein we show that the simple on-line addition of an aqueous formaldehyde solution not only enhances the sensitivity of the procedure by two orders of magnitude, but also provides a remarkable improvement in the selectivity of the reagent towards thiols such as glutathione (compared to phenols and amino acids that do not possess a thiol group). This enhanced mode of detection was applied to the determination of glutathione and its corresponding disulfide species in homogenised striatum samples taken from both wild type mice and the R6/1 transgenic mouse model of Huntington's disease, at both 8 and 12 weeks of age. No significant difference was observed between the GSH/GSSG ratios of wild type mice and R6/1 mice at either age group, suggesting that the early disease progression had not significantly altered the intracellular redox environment.