Implications of insecticide resistance for malaria vector control with long-lasting insecticidal nets: trends in pyrethroid resistance during a WHO-coordinated multi-country prospective study.

BACKGROUND: Increasing pyrethroid resistance has been an undesirable correlate of the rapid increase in coverage of insecticide-treated nets (ITNs) since 2000. Whilst monitoring of resistance levels has increased markedly over this period, longitudinal monitoring is still lacking, meaning the temporal and spatial dynamics of phenotypic resistance in the context of increasing ITN coverage are unclear. METHODS: As part of a large WHO-co-ordinated epidemiological study investigating the impact of resistance on malaria infection, longitudinal monitoring of phenotypic resistance to pyrethroids was undertaken in 290 clusters across Benin, Cameroon, India, Kenya and Sudan. Mortality in response to pyrethroids in the major anopheline vectors in each location was recorded during consecutive years using standard WHO test procedures. Trends in mosquito mortality were examined using generalised linear mixed-effect models. RESULTS: Insecticide resistance (using the WHO definition of mortality < 90%) was detected in clusters in all countries across the study period. The highest mosquito mortality (lowest resistance frequency) was consistently reported from India, in an area where ITNs had only recently been introduced. Substantial temporal and spatial variation was evident in mortality measures in all countries. Overall, a trend of decreasing mosquito mortality (increasing resistance frequency) was recorded (Odds Ratio per year: 0.79 per year (95% CI: 0.79-0.81, P < 0.001). There was also evidence that higher net usage was associated with lower mosquito mortality in some countries. DISCUSSION: Pyrethroid resistance increased over the study duration in four out of five countries. Insecticide-based vector control may be compromised as a result of ever higher resistance frequencies

© 2012 INFORMS Overflow Networks: Approximations and

Motivated by call center cosourcing problems, we consider a service network operated under an overflow mechanism. Calls are first routed to an in-house (or dedicated) service station that has a finite waiting room. If the waiting room is full, the call is overflowed to an outside provider (an overflow station) that might also be serving overflows from other stations. We establish approximations for overflow networks with many servers under a resource-pooling assumption that stipulates, in our context, that the fraction of overflowed calls is nonnegligible. Our two main results are (i) an approximation for the overflow processes via limit theorems and (ii) asymptotic independence between each of the in-house stations and the overflow station. In particular, we show that, as the system becomes large, the dependency between each in-house station and the overflow station becomes negligible. Independence between stations in overflow networks is assumed in the literature on call centers, and we provide a rigorous support for those useful heuristics. Subject classifications: overflow networks; cosourcing; heavy-traffic approximations; separation of time scales

限界効用理論の含意

はじめに Ⅰ 限界効用理論 　§1 価値は効用によって決まる　§2 全部効用と最終効用度(限界効用)　§3 最終効用度の均等　Ⅱ 限界効用理論と唯物史観　§4 生活が意識を規定する　§5 生活と意識の交互作用　§6 唯物史観と限界効用理論　Ⅲ限界効用理論と労働価値説　§7 限界効用理論の倫理的中立性