268 research outputs found

    SZTAKI desktop grid: building a scalable, secure platform for desktop grid computing

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    In this paper we present a concept how separate desktop grids can be used as building blocks for larger scale grids by organizing them in a hierarchical tree. We describe an enhanced security model which satisfies the requirements of the hierarchical setup and is aimed for real-world deployment

    MECHANISM OF CATIONIC LACTAM POLYMERIZATION

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    The authors suggested a new mechanism for the interpretation of cationic lactam polymerization according to which in the chain propagation reaction. through the appropriate intermediates. compounds belonging to various polymer homologous series are formed and additional polymerization processes are superimposed onto the original ones. On the basis of the new mechanism a kinetic model has been developed by the computer simulation of which rate and equilibrium constants could be determined. The latter enabled. a good quantitative description of polymerization

    SZTAKI desktop grid: a modular and scalable way of building large computing grids

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    So far BOINC based desktop grid systems have been applied at the global computing level. This paper describes an extended version of BOINC called SZTAKI desktop grid (SZDG) that aims at using desktop grids (DGs) at local (enterprise/institution) level. The novelty of SZDG is that it enables the hierarchical organisation of local DGs, i.e., clients of a DG can be DGs at a lower level that can take work units from their higher level DG server. More than that, even clusters can be connected at the client level and hence work units can contain complete MPI programs to be run on the client clusters. In order to easily create master/worker type DG applications a new API, called as the DC-API has been developed. SZDG and DC-API has been successfully applied both at the global and local level, both in academic institutions and in companies to solve problems requiring large computing power

    Glycogen Synthase Kinase 3: Ion Channels, Plasticity, and Diseases

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    Glycogen synthase kinase 3β (GSK3) is a multifaceted serine/threonine (S/T) kinase expressed in all eukaryotic cells. GSK3β is highly enriched in neurons in the central nervous system where it acts as a central hub for intracellular signaling downstream of receptors critical for neuronal function. Unlike other kinases, GSK3β is constitutively active, and its modulation mainly involves inhibition via upstream regulatory pathways rather than increased activation. Through an intricate converging signaling system, a fine-tuned balance of active and inactive GSK3β acts as a central point for the phosphorylation of numerous primed and unprimed substrates. Although the full range of molecular targets is still unknown, recent results show that voltage-gated ion channels are among the downstream targets of GSK3β. Here, we discuss the direct and indirect mechanisms by which GSK3β phosphorylates voltage-gated Na+ channels (Nav 1.2 and Nav 1.6) and voltage-gated K+ channels (Kv 4 and Kv 7) and their physiological effects on intrinsic excitability, neuronal plasticity, and behavior. We also present evidence for how unbalanced GSK3β activity can lead to maladaptive plasticity that ultimately renders neuronal circuitry more vulnerable, increasing the risk for developing neuropsy-chiatric disorders. In conclusion, GSK3β-dependent modulation of voltage-gated ion channels may serve as an important pharmacological target for neurotherapeutic development

    Distributed Environment for Efficient Virtual Machine Image Management in Federated Cloud Architectures

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    The use of Virtual Machines (VM) in Cloud computing provides various benefits in the overall software engineering lifecycle. These include efficient elasticity mechanisms resulting in higher resource utilization and lower operational costs. VM as software artifacts are created using provider-specific templates, called VM images (VMI), and are stored in proprietary or public repositories for further use. However, some technology specific choices can limit the interoperability among various Cloud providers and bundle the VMIs with nonessential or redundant software packages, leading to increased storage size, prolonged VMI delivery, stagnant VMI instantiation and ultimately vendor lock-in. To address these challenges, we present a set of novel functionalities and design approaches for efficient operation of distributed VMI repositories, specifically tailored for enabling: (i) simplified creation of lightweight and size optimized VMIs tuned for specific application requirements; (ii) multi-objective VMI repository optimization; and (iii) efficient reasoning mechanism to help optimizing complex VMI operations. The evaluation results confirm that the presented approaches can enable VMI size reduction by up to 55%, while trimming the image creation time by 66%. Furthermore, the repository optimization algorithms, can reduce the VMI delivery time by up to 51% and cut down the storage expenses by 3%. Moreover, by implementing replication strategies, the optimization algorithms can increase the system reliability by 74%

    Petrological evidence in support of the death mask model for Ediacaran soft-bodied preservation in South Australia

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    Microbially mediated early diagenetic pyrite formation in the immediate vicinity of organic material has been the favoured mechanism by which to explain widespread preservation of soft-bodied organisms in late Ediacaran sedimentary successions, but an alternative rapid silicification model has been proposed for macrofossil preservation in sandstones of the Ediacara Member in South Australia. We here provide petrological evidence from Nilpena National Heritage Site and Ediacara Conservation Park to demonstrate the presence of grain-coating iron oxides, framboidal hematite, and clay minerals along Ediacara Member sandstone bedding planes, including fossil-bearing bed soles. SEM and petrographic data reveal that framboids and grain coatings, which we interpret as oxidized pyrite, formed before the precipitation of silica cements. In conjunction with geochemical and taphonomic considerations, our data suggest that anactualistically high concentrations of silica need not be invoked to explain Ediacara Member fossil preservation: we conclude that the pyritic ‘death mask’ model remains compelling.AGL is funded by the Natural Environment Research Council [grant number NE/L011409/2]. SM acknowledges support from the European Union’s Horizon 2020 Research and Innovation Programme under Marie Skłodowska-Curie grant agreement 747877 ... JJM recognises support from Mitacs ..

    EDGeS: a bridge between desktop grids and service grids

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    Desktop grids and service grids widely used by their different users communities as efficient solutions for making full use of computing power and achieving loads balances across Intranet or Internet. Nevertheless,little work has been done to combine these two grids technologies together to establish a seamless and vast grid resources pool. In this paper we will present a new European FP7 infrastructure project:EDGeS (enabling desktop grids for e-science), which aim to build technological bridges to facilitate interoperability between desktop grid and service grid. We give also a taxonomy of existing grid systems: desktop grids such as BONIC and XtremWeb, service grids such as EGEE. Then we describe furtherly our solution for identifying translation technologies for porting applications between desktop grids and service grids, and vice versa. There are three themes in our solution, which discuss actual popular bridging technologies, user access issues, and distributed data issues about deployment and application development

    ENTICE VM image analysis and optimised fragmentation

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    Virtual machine (VM) images (VMIs) often share common parts of significant size as they are stored individually. Using existing de-duplication techniques for such images are non-trivial, impose serious technical challenges, and requires direct access to clouds' proprietary image storages, which is not always feasible. We propose an alternative approach to split images into shared parts, called fragments, which are stored only once. Our solution requires a reasonably small set of base images available in the cloud, and additionally only the increments will be stored without the contents of base images, providing significant storage space savings. Composite images consisting of a base image and one or more fragments are assembled on- demand at VM deployment. Our technique can be used in conjunction with practically any popular cloud solution, and the storage of fragments is independent of the proprietary image storage of the cloud provider
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