A quorum system is a collection of subsets of servers, every two of which intersect. Quorum systems have been suggested as a tool for concurrency control in replicated databases almost twenty years ago. They promised to guarantee strict consistency and to provide high availability and fault-tolerance in the face of server crashes and network partitions. Despite these promises, current commercia...

This report summarizes the state of the art in the research area of quorum systems as represented by the papers [PM01], [ES00], [MRW97], and [AMR+00]. Quorum systems are used in fault tolerant distributed computing systems for ensuring the availability of a replicated service and replicated data, even if the replicated servers fail by crashing benignly or in a byzantine, i.e. arbitrary way. Quo...

Disease caused by antibiotic resistant pathogens is becoming a serious problem, both in human and veterinary medicine. The inhibition of quorum sensing, bacterial cell-to-cell communication, is a promising alternative strategy to control disease. In this study, we determined the quorum sensing-disrupting activity of 20 thiophenones towards the quorum sensing model bacterium V. harveyi. In order...

Vibrio fischeri possesses two quorum-sensing systems, ain and lux, using acyl homoserine lactones as signaling molecules. We have demonstrated previously that the ain system activates luminescence gene expression at lower cell densities than those required for lux system activation and that both systems are essential for persistent colonization of the squid host, Euprymna scolopes. Here, we ask...

The discovery of antibiotics early in the past century marked the beginning of active control and prevention of infectious microbial diseases. However, extensive use of antibiotics has also unavoidably resulted in the emergence of ‘superbugs’ that resist conventional antibiotics. The finding that many pathogens rely on cell-to-cell communication mechanisms, known as quorum sensing, to synchroni...

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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. The un-availability of a quorum system is the probability of the event that no live quorum exists in the system. When such an event occur...

W e discuss how to lock replicated objects by extending the quorum concept and perform methods o n replicas in a nested invocation. Each method i s issued to a quorum. If a pair of methods are compatible, their quorums may not intersect in our protocol even i f one of the methods is an update type. If a method t is invoked o n multiple replicas and each instance of t invokes another update meth...

Quorum Sensing is a special system between bacteria to communicate with the signal molecules. Propolis resin collected from plants by honey bees. The present study examined anti-quorum sensing and antimicrobial activities of water ethanol extracts propolis. propolis were studied against Escherichia coli ATCC 25922 Gram (-), Listeria monocytogenes 7644, Streptococcus mutans CNCTC 8/77, Staphyloc...

Quorum-based Byzantine fault-tolerant protocols for replicated state machines allow replicas to respond to client requests without explicitly agreeing on the request ordering. As long as concurrent write operations do not conflict, quorum-based protocols are more efficient than agreement-based protocols. However, resolving conflicting writes and bringing replicas up-to-date with each other is a...