Election results and the Sznajd model on Barabasi network

The network of Barabasi and Albert, a preferential growth model where a new node is linked to the old ones with a probability proportional to their connectivity, is applied to Brazilian election results. The application of the Sznajd rule, that only agreeing pairs of people can convince their neighbours, gives a vote distribution in good agreement with reality.Comment: 7 pages including two figures, for Eur. Phys. J.

Desulfonation of aliphatic sulfonates by Pseudomonas aeruginosa PAO

Pseudomonas aeruginosa PAO1 used a broad range of alkanesulfonic acids as sole sulfur source for growth, with molar growth yields of 2.2 to 2.9 kg protein per mol sulfur. 4-Phenylbutane-1-sulfonate was desulfonated in vivo to yield 4-pheny 1-1-butyric acid quantitatively as the sole product, suggesting that the desulfonation mechanism is the same as when alkanesulfonates serve as a carbon source for growth. This contrasts with aromatic sulfonate utilization in other organisms, where different desulfonation reactions are used to provide carbon and sulfur. Desulfonation of alkanesulfonates to provide sulfur was repressed by sulfate or thiocyanate, and derepressed in their absence. The alkanesulfonatase system is hence controlled as part of the sulfate starvation-induced stimulo

Riding the sulfur cycle - metabolism of sulfonates and sulfate esters in Gram-negative bacteria

Sulfonates and sulfate esters are widespread in nature, and make up over 95% of the sulfur content of most aerobic soils. Many microorganisms can use sulfonates and sulfate esters as a source of sulfur for growth, even when they are unable to metabolize the carbon skeleton of the compounds. In these organisms, expression of sulfatases and sulfonatases is repressed in the presence of sulfate, in a process mediated by the LysR-type regulator protein CysB, and the corresponding genes therefore constitute an extension of the cys regulon. Additional regulator proteins required for sulfonate desulfonation have been identified in Escherichia coli (the Cbl protein) and Pseudomonas putida (the AsfR protein). Desulfonation of aromatic and aliphatic sulfonates as sulfur sources by aerobic bacteria is oxygen-dependent, carried out by the α-ketoglutarate-dependent taurine dioxygenase, or by one of several FMNH2-dependent monooxygenases. Desulfurization of condensed thiophenes is also FMNH2-dependent, both in the rhodococci and in two Gram-negative species. Bacterial utilization of aromatic sulfate esters is catalyzed by arylsulfatases, most of which are related to human lysosomal sulfatases and contain an active-site formylglycine group that is generated post-translationally. Sulfate-regulated alkylsulfatases, by contrast, are less well characterized. Our increasing knowledge of the sulfur-regulated metabolism of organosulfur compounds suggests applications in practical fields such as biodesulfurization, bioremediation, and optimization of crop sulfur nutritio

Construction of improved plasmid vectors for promoter characterization in Pseudomonas aeruginosa and other Gram-negative bacteria

We report the construction of two broad host range promoter-probe plasmid vectors for rapid analysis of promoters in Gram-negative bacteria. The new vectors, pME4507 and pME4510, carry carbenicillin and gentamycin resistance genes, respectively, and are small sized (4 kb) with a flexible multiple cloning site to facilitate directional cloning of putative promoter elements. The vectors allow rapid plate-based screening for promoter activities, using β-galactosidase as the reporter enzyme. In the absence of an inserted promoter fragment, they display very low background activity, making them a useful tool for analysis of low expression level promoter

An interoperable and self-adaptive approach for SLA-based service virtualization in heterogeneous Cloud environments

Cloud computing is a newly emerged computing infrastructure that builds on the latest achievements of diverse research areas, such as Grid computing, Service-oriented computing, business process management and virtualization. An important characteristic of Cloud-based services is the provision of non-functional guarantees in the form of Service Level Agreements (SLAs), such as guarantees on execution time or price. However, due to system malfunctions, changing workload conditions, hard- and software failures, established SLAs can be violated. In order to avoid costly SLA violations, flexible and adaptive SLA attainment strategies are needed. In this paper we present a self-manageable architecture for SLA-based service virtualization that provides a way to ease interoperable service executions in a diverse, heterogeneous, distributed and virtualized world of services. We demonstrate in this paper that the combination of negotiation, brokering and deployment using SLA-aware extensions and autonomic computing principles are required for achieving reliable and efficient service operation in distributed environments. © 2012 Elsevier B.V. All rights reserved

An SLA-based resource virtualization approach for on-demand service provision

Cloud computing is a newly emerged research infrastructure that builds on the latest achievements of diverse research areas, such as Grid computing, Service-oriented computing, business processes and virtualization. In this paper we present an architecture for SLA-based resource virtualization that provides an extensive solution for executing user applications in Clouds. This work represents the first attempt to combine SLA-based resource negotiations with virtualized resources in terms of on-demand service provision resulting in a holistic virtualization approach. The architecture description focuses on three topics: agreement negotiation, service brokering and deployment using virtualization. The contribution is also demonstrated with a real-world case study

Cloud Workload Prediction by Means of Simulations

Clouds hide the complexity of maintaining a physical infrastructure with a disadvantage: they also hide their internal workings. Should users need to know about these details e.g., to increase the reliability or performance of their applications, they would need to detect slight behavioural changes in the underlying system. Existing solutions for such purposes offer limited capabilities. This paper proposes a technique for predicting background workload by means of simulations that are providing knowledge of the underlying clouds to support activities like cloud orchestration or workflow enactment. We propose these predictions to select more suitable execution environments for scientific workflows. We validate the proposed prediction approach with a biochemical application