We investigate issues related to the probe complexity of the And-Or quorum system and its implementation in a dynamic environment. Our contribution is twofold: We first analyze the algorithmic probe complexity of the And-Or quorum system, and present two optimal algorithms. The first is a non-adaptive algorithm with O( √ n log n) probe complexity, which matches a known lower bound. The second i...

Quorum systems serve as a basic tool providing a uniform and reliable way to achieve coordination in a distributed system. They are useful for distributed and replicated databases, name servers, mutual exclusion, and distributed access control and signatures. Traditionally, two basic methods have been used to evaluate quorum systems: the analytical approach, and simulation. This paper proposes ...

Quorum sensing, a population density-dependent mechanism for bacterial communication and gene regulation, plays a crucial role in the symbiosis between alfalfa and its symbiont Sinorhizobium meliloti. The Sin system, one of three quorum sensing systems present in S. meliloti, controls the production of the symbiotically active exopolysaccharide EPS II. Based on DNA microarray data, the Sin syst...

.......................................................................................................................................................... 5 PAPERS IN THIS THESIS.................................................................................................................................. 6 ABBREVIATIONS ...........................................................................

The bacterium Pseudomonas aeruginosa is an opportunistic human pathogen that uses a quorum sensing signal cascade to activate expression of dozens of genes when sufficient population densities have been reached. Quorum sensing controls production of several key virulence factors, including secreted proteases such as elastase. Cooperating groups of bacteria growing on protein are susceptible to ...

Data replication is a central mechanism for the engineering of fault-tolerant distributed systems, and is used in the realization of most cloud computing services. This paper explores the use of Coloured Petri Nets (CPNs) for model-based testing of quorum-based distributed systems. We have used model-based testing to validate a distributed storage implemented using the Go language and the Gorum...

Quorum sensing is a communication system by which bacteria use signal molecules to induce physiological response. In natural marine environments, quorum suspected occur in regions with high cell densities. Free-living bacteria, however, are largely believed exist at concentrations too low make of density-dependent quorum-sensing system. Due so-called ‘free-living’ inhabiting gels composed exopo...

Quorum sensing is a bacterial mechanism used to synchronize the coordinated response of a microbial population. Because quorum sensing in Gram-negative bacteria depends on release and detection of a diffusible signaling molecule (autoinducer) among a multicellular group, it is considered a simple form of cell-cell communication for the purposes of mathematical analysis. Stochastic equation syst...

Quorum quenching (QQ) enzymes, which disrupt the quorum sensing signaling process, have attracted considerable attention as new antimicrobial agents. However, their low catalytic efficiency for quorum sensing molecules remains a challenge. Herein, we present an antisense RNA-based high-throughput screen system for directed evolution of a quorum quenching enzyme. The screening system was constru...

We deal with storage systems and quorum systems for a dynamic environment where servers may join and leave the system. We suggest a file storage system construction based on the ‘And-Or’ quorum system, that has a O( √ n) write complexity, O( √ n log n) read complexity and a constant data blowup-ratio, where n represents the number of processors in the network. Our construction is fault-tolerant...