A Methodology to Engineer and Validate Dynamic Multi-level Multi-agent Based Simulations

This article proposes a methodology to model and simulate complex systems, based on IRM4MLS, a generic agent-based meta-model able to deal with multi-level systems. This methodology permits the engineering of dynamic multi-level agent-based models, to represent complex systems over several scales and domains of interest. Its goal is to simulate a phenomenon using dynamically the lightest representation to save computer resources without loss of information. This methodology is based on two mechanisms: (1) the activation or deactivation of agents representing different domain parts of the same phenomenon and (2) the aggregation or disaggregation of agents representing the same phenomenon at different scales.Comment: Presented at 3th International Workshop on Multi-Agent Based Simulation, Valencia, Spain, 5th June 201

Study protocol for an international, multicentre stepped-wedge cluster randomised trial to evaluate the impact of a digital antimicrobial stewardship smartphone application

Introduction With the widespread use of electronic health records and handheld electronic devices in hospitals, informatics-based antimicrobial stewardship interventions hold great promise as tools to promote appropriate antimicrobial drug prescribing. However, more research is needed to evaluate their optimal design and impact on quantity and quality of antimicrobial prescribing. Methods and analysis Use of smartphone-based digital stewardship applications (apps) with local guideline directed empirical antimicrobial use by physicians will be compared with antimicrobial prescription as per usual as primary outcome in three hospitals in the Netherlands, Sweden and Switzerland. Secondary outcomes will incl

Detecting ancient codispersals and host shifts by double dating of host and parasite phylogenies: Application in proctophyllodid feather mites associated with passerine birds

Inferring cophylogeographic events requires matching the timing of these events on both host and symbiont (e.g., parasites) phylogenies because divergences of hosts and their symbionts may not temporally coincide, and host switches may occur. We investigate a large radiation of birds (Passeriformes) and their permanent symbionts, the proctophyllodid feather mites (117 species from 116 bird species; six genes, 11,468 nt aligned) using two time‐calibration strategies for mites: fossils only and host phylogeography only. Out of 10 putative cophylogeographic events 4 agree in timing for both symbiont and host events being synchronous co‐origins or codispersals; three were based on host shifts, but agree in timing being very close to the origin of modern hosts; two disagree; and one large basal mite split was seemingly independent from host phylogeography. Among these events was an ancient (21–25.3 Mya), synchronous codispersal from the Old World leading to the origin and diversifications of New World emberizoid passerids and their mites, the thraupis + quadratus species groups of Proctophyllodes. Our framework offers a more robust detection of host and symbiont cophylogeographic events (as compared to host‐symbiont reconciliation analysis and using host phylogeography for time‐calibration) and provides independent data for testing alternative hypotheses on timing of host diversification and dispersal.Peer Reviewedhttps://deepblue.lib.umich.edu/bitstream/2027.42/138927/1/evo13309-sup-0003-figureS3.pdfhttps://deepblue.lib.umich.edu/bitstream/2027.42/138927/2/evo13309.pdfhttps://deepblue.lib.umich.edu/bitstream/2027.42/138927/3/evo13309-sup-0006-figureS6.pdfhttps://deepblue.lib.umich.edu/bitstream/2027.42/138927/4/evo13309_am.pdfhttps://deepblue.lib.umich.edu/bitstream/2027.42/138927/5/evo13309-sup-0009-figureS9.pdfhttps://deepblue.lib.umich.edu/bitstream/2027.42/138927/6/evo13309-sup-0005-figureS5.pdfhttps://deepblue.lib.umich.edu/bitstream/2027.42/138927/7/evo13309-sup-0004-figureS4.pdfhttps://deepblue.lib.umich.edu/bitstream/2027.42/138927/8/evo13309-sup-0002-figureS2.pdfhttps://deepblue.lib.umich.edu/bitstream/2027.42/138927/9/evo13309-sup-0008-figureS8.pd

Brachytic2/ZmABCB1 functions in IAA export from intercalary meristems

Dwarfism traits in Zea mays are regulated by multiple factors including the hormone auxin. Dwarf brachytic2 (br2) mutants harbour lesions in the gene encoding an orthologue of Arabidopsis thaliana ABCB1 which functions in auxin efflux out of meristematic regions in the shoot and root. br2 mesocotyls and coleoptiles exhibit reduced auxin transport. However, the dwarf stature of br2 derives from shortened lower internodes whilst the upper portion of the plant is completely normal. As such, it is counter-intuitive to attribute br2 dwarfism exclusively to reduced auxin export out of the shoot apex. Arabidopsis abcb1 mutants exhibit only minor reductions in auxin transport and plant height unless combined with mutations in the ABCB19 auxin transporter. Phylogenetic modelling analysis excludes the possibility that BR2 is more closely related to ABCB19 which has three more closely related orthologues in maize. BR2 is expressed in nodal meristems, and analyses of auxin transport and content indicate that BR2 function in these grass-specific tissues is analogous to ABCB1 function in the shoot and root apex of Arabidopsis. These results indicate that ABCB1/BR2 function is conserved between dicots and monocots, but also suggests that this function must be understood in the context of the segmental organization of grass plants

Global Patterns and Drivers of Ecosystem Functioning in Rivers and Riparian Zones

River ecosystems receive and process vast quantities of terrestrial organic carbon, the fate of which depends strongly on microbial activity. Variation in and controls of processing rates, however, are poorly characterized at the global scale. In response, we used a peer-sourced research network and a highly standardized carbon processing assay to conduct a global-scale field experiment in greater than 1000 river and riparian sites. We found that Earth’s biomes have distinct carbon processing signatures. Slow processing is evident across latitudes, whereas rapid rates are restricted to lower latitudes. Both the mean rate and variability decline with latitude, suggesting temperature constraints toward the poles and greater roles for other environmental drivers (e.g., nutrient loading) toward the equator. These results and data set the stage for unprecedented “next-generation biomonitoring” by establishing baselines to help quantify environmental impacts to the functioning of ecosystems at a global scale

Seismic structure across the rift valley of the Mid-Atlantic Ridge at 23°20′ (MARK area): Implications for crustal accretion processes at slow spreading ridges

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