An empirical analysis of residential meter degradation in Gauteng Province, South Africa

Understanding the degradation rates of water meters assists utilities in making informed management decisions regarding meter replacement programmes and meter technology selection. This research evaluated the performance of 200 residential meters of two different technologies commonly used in Gauteng, South Africa, namely velocity meters and volumetric meters. This was done by conducting empirical meter testing in a verification laboratory and evaluating the degradation accuracy of each meter technology based on age and volume. Results indicate that velocity meters experience an accuracy degradation rate of approximately −1.13% per 1 000 kL of volume passed through the meter and an inferred initial error of −10.80%. Meter accuracy was not strongly related to age of the velocity meters tested. Volumetric meters did not exhibit a strong link with either age or accumulated volume, indicated by a loose grouping of results. These results indicate that accumulated volume of a velocity meter is a more reliable predictor of accuracy than age, and should be used when planning replacement strategies for velocity meters. Additionally, the lack of predictable degradation rates related to either age or accumulated volume for volumetric meters indicates that the accuracy of volumetric meters is primarily affected by other external factors, such as particulates or entrained air in the water network. These findings will assist utility managers in predicting the accuracy of their meter fleet and in making informed decisions regarding meter replacement.

Improvement of Student Critical Thinking Skills with the Natural Product Mini Project Laboratory Learning

This research aims to investigate effect of learning using natural product mini project laboratory on students’ critical thinking skills. The research was conducted on sixth semester of 59 students of chemistry and chemistry education program from one of the state universities in West Nusa Tenggara, Indonesia in 2012/2013. This research revealed class where the student learn using natural product mini project laboratory had more critical thinking skills than those using verification laboratory. The average n-gain of critical thinking skills for experiment class was 0.58 while for the control class was 0.37. The highest n-gain in the experiment class was 0.70 for “deciding on an action (selecting criteria to judge possible solutions) indicators”, while the smallest n-gain was 0.47 for “the making and judging value of judgments (balancing, weighing, and deciding) indicators. We concluded that the natural product mini project laboratory was better than verification laboratory in improving the students’ critical thinking skills.

Validation and verification of automated urine particle analysers

There is often uncertainty on how validation and verification of newly introduced tests should be conducted, and there is a real risk of verification becoming a meaningless ritual, rather than a useful exercise. This article reviews the literature and makes recommendations regarding the validation and verification of automated urine particles analysers. A generic practical approach to verification is also recommended. For many analysers, the accuracy of white blood cells, epithelial cells and bacterial counts is corroborated by a number of independent evaluations; thus, any verification laboratory work could be significantly scaled down. Conversely, in the scenario that automated urine microscopy is used as a screening test to reduce the number of urines cultured, the extremely variable performance reported in the literature requires a full-scale verification to define the optimal cut-off values that give a sensitivity of >98% with the local settings and circumstances. With some analysers, the risk of carry-over also needs to be assessed, as part of the verification process, and exclusion criteria (urines requiring culture regardless of the microscopy results) need to be well defined, as there are patients or specimen types for which the performance of microscopy as a screening test may not be adequate.