Game-Theoretic Optimal Power-Link Quality Topology Control in Wireless Sensor Networks

One of the most significant problems in Wireless Sensor Network (WSN) deployment is the generation of topologies that maximize transmission reliability and guarantee network connectivity while also maximizing the network’s lifetime. Transmission power settings have a large impact on the aforementioned factors. Increasing transmission power to provide coverage is the intuitive solution yet with it may come with lower packet reception and shorter network lifetime. However, decreasing the transmission power may result in the network being disconnected. To balance these trade-offs we propose a discrete strategy game-theoretic solution, which we call TopGame that aims to maximize the reliability between nodes while using the most appropriate level of transmission power that guarantees connectivity. In this paper, we provide the conditions for the convergence of our algorithm to a pure Nash equilibrium as well as experimental results. Here we show, using the Indriya WSN testbed, that TopGame is more energy-efficient and approaches a similar packet reception ratio with the current closest state of the art protocol ART. Finally, we provide a methodology for further optimization of our work using an indicator function to distinguish between satisfactory and poor links

Antimicrobial de-escalation in the critically ill patient and assessment of clinical cure: the DIANA study

Purpose: The DIANA study aimed to evaluate how often antimicrobial de-escalation (ADE) of empirical treatment is performed in the intensive care unit (ICU) and to estimate the effect of ADE on clinical cure on day 7 following treatment initiation. Methods: Adult ICU patients receiving empirical antimicrobial therapy for bacterial infection were studied in a prospective observational study from October 2016 until May 2018. ADE was defined as (1) discontinuation of an antimicrobial in case of empirical combination therapy or (2) replacement of an antimicrobial with the intention to narrow the antimicrobial spectrum, within the first 3 days of therapy. Inverse probability (IP) weighting was used to account for time-varying confounding when estimating the effect of ADE on clinical cure. Results: Overall, 1495 patients from 152 ICUs in 28 countries were studied. Combination therapy was prescribed in 50%, and carbapenems were prescribed in 26% of patients. Empirical therapy underwent ADE, no change and change other than ADE within the first 3 days in 16%, 63% and 22%, respectively. Unadjusted mortality at day 28 was 15.8% in the ADE cohort and 19.4% in patients with no change [p = 0.27; RR 0.83 (95% CI 0.60\u20131.14)]. The IP-weighted relative risk estimate for clinical cure comparing ADE with no-ADE patients (no change or change other than ADE) was 1.37 (95% CI 1.14\u20131.64). Conclusion: ADE was infrequently applied in critically ill-infected patients. The observational effect estimate on clinical cure suggested no deleterious impact of ADE compared to no-ADE. However, residual confounding is likely

Composite source models for multi-dimensional signal coding under rate-distortion constraints

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Investigation of thermo-catalytic decomposition of metal-iodide aerosols due to passage through hydrogen recombiners

Passive autocatalytic recombiners (PARs) are a means of preventing hydrogen accumulation in the containment building of a water-cooled nuclear reactor during an accident. A potential problem exists concerning suspended radioactive aerosols: particles passing through the catalytic elements are heated up with significant evaporation of more volatile chemical species. The aerosols, vapours and carrier-gas mixture may chemically react resulting potentially in conversion of easily-retained aerosol material into more troublesome vapours and gases. An experimental programme, RECI, demonstrated that potential exists for PARs to generate volatile forms of iodine, namely molecular iodine, by thermo-catalytic decomposition of metal-iodide aerosols. Here, analysis of RECI results aided by two computer codes, one a field code the other a lumped-parameter approach, provides significant insight into the iodide-iodine phenomenology where, in particular, the rapid cooling of the reacting mixture explains the persistence of volatile species downstream at ambient conditions. While understanding of the phenomenology has progressed, the current results cannot be extrapolated to the reactor case since further experiments are needed reproducing more closely expected accident conditions. © 2009 Elsevier B.V. All rights reserved