Decentralized Connectivity-Preserving Deployment of Large-Scale Robot Swarms

We present a decentralized and scalable approach for deployment of a robot swarm. Our approach tackles scenarios in which the swarm must reach multiple spatially distributed targets, and enforce the constraint that the robot network cannot be split. The basic idea behind our work is to construct a logical tree topology over the physical network formed by the robots. The logical tree acts as a backbone used by robots to enforce connectivity constraints. We study and compare two algorithms to form the logical tree: outwards and inwards. These algorithms differ in the order in which the robots join the tree: the outwards algorithm starts at the tree root and grows towards the targets, while the inwards algorithm proceeds in the opposite manner. Both algorithms perform periodic reconfiguration, to prevent suboptimal topologies from halting the growth of the tree. Our contributions are (i) The formulation of the two algorithms; (ii) A comparison of the algorithms in extensive physics-based simulations; (iii) A validation of our findings through real-robot experiments.Comment: 8 pages, 8 figures, submitted to IROS 201

Lcc1 and Lcc5 are the main laccases secreted in liquid cultures of Coprinopsis cinerea strains

The litter-degrading dung fungus Coprinopsis cinerea has the high number of seventeen different laccase genes. In this work, ten different monokaryons were compared in their ability to produce laccases in two different complete media at different temperatures. Few strains showed laccase activity at the optimal growth temperature of 37 °C. Nine of the strains gave laccase activities between 0.2 and 5.9 U mL(−1) at the suboptimal temperature of 25 °C in mKjalke medium. Laccase activities in YMG/T medium were detected for only three strains (0.5–4.5 U mL(−1)). Zymograms of supernatants from mKjalke medium resulted in total in 10 different laccase bands but strains differed in distribution. LC–MS/MS analysis with Mascot searches of the annotated C. cinerea genome identified isoenzymes from five different genes (Lcc1, Lcc2, Lcc5, Lcc9 and Lcc10) and of Lcc1 three and of Lcc5 two distinct electrophoretical forms. Lcc1 and Lcc5 were expressed in all laccase positive strains, but not all forms were found in all of the strains. Lcc2, Lcc9 and Lcc10 occurred only in three strains as minor laccases, indicating that Lcc1 and Lcc5 are the main laccases of C. cinerea secreted in liquid mKjalke medium. ELECTRONIC SUPPLEMENTARY MATERIAL: The online version of this article (doi:10.1007/s10482-013-9883-7) contains supplementary material, which is available to authorized users

The discriminatory power of MALDI-TOF mass spectrometry to differentiate between isogenic teicoplanin-susceptible and teicoplanin-resistant strains of methicillin-resistant Staphylococcus aureus

To explore the discriminatory power of matrix-assisted laser desorption ionization-time of flight mass spectrometry (MALDI-TOF MS) for detecting subtle differences in isogenic isolates, we tested isogenic strains of Staphylococcus aureus differing in their expression of resistance to methicillin or teicoplanin. More important changes in MALDI-TOF MS spectra were found with strains differing in methicillin than in teicoplanin resistance. In comparison, very minor or no changes were recorded in pulsed-field gel electrophoresis profiles or peptidoglycan muropeptide digest patterns of these strains, respectively. MALDI-TOF MS might be useful to detect subtle strain-specific differences in ionizable components released from bacterial surfaces and not from their peptidoglycan networ

Uncertain outcomes of geotechnical work illustrated with the example of a road tunnel

This paper presents a number of factors which influence the design and construction of a geotechnical structure, i.e. a road tunnel. For this type of structure, it is necessary to thoroughly examine the geological conditions and the properties of the rock mass. Research carried out on the basis of drilling gives only local results, which consequently only provides an estimated description of the characteristics and properties of the rock mass