167 research outputs found

    Mechanostimulation of Medicago truncatula leads to enhanced levels of jasmonic acid

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    Wounding of plants leads to endogenous rise of jasmonic acid (JA) accompanied with the expression of a distinct set of genes. Among them are those coding for the allene oxide cyclase (AOC) that catalyses a regulatory step in JA biosynthesis, and for 1-deoxy-D-xylulose 5-phosphate synthase 2 (DXS2), an enzyme involved in isoprenoid biosynthesis. To address the question how roots and shoots of Medicago truncatula respond to mechanostimulation and wounding, M. truncatula plants were analysed in respect to JA levels as well as MtAOC1 and MtDXS2-1 transcript accumulation. Harvest-caused mechanostimulation resulted in a strong, but transient increase in JA level in roots and shoots followed by a transient increase in MtAOC1 transcript accumulation. Additional wounding of either shoots or roots led to further increased JA and MtAOC1 transcript levels in shoots, but not in roots. In situ hybridization revealed a cell-specific transcript accumulation of MtAOC1 after mechanostimulation in companion cells of the vascular tissue of the stem. AOC protein, however, was found to occur constitutively in vascular bundles. Further, transcript accumulation of MtDXS2-1 was similar to that of MtAOC1 in shoots, but its transcript levels were not enhanced in roots. Repeated touching of shoots increased MtAOC1 transcript levels and led to significantly shorter shoots and increased biomass. In conclusion, M. truncatula plants respond very sensitively to mechanostimulation with enhanced JA levels and altered transcript accumulation, which might contribute to the altered phenotype after repeated touching of plants

    Activation and Oxidation of Mesitylene C–H Bonds by (Phebox)Iridium(III) Complexes

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    Production of Single W Bosons at LEP

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    We report on the observation of single W boson production in a data sample collected by the L3 detector at LEP2. The signal consists of large missing energy final states with a single energetic lepton or two hadronic jets. The cross-section is measured to be 0.610.33+0.43±0.05  pb0.61^{+0.43}_{-0.33} \pm 0.05 \; \rm{pb} at the centre of mass energy \sqrt{s}=172 \GeV{}, consistent with the Standard Model expectation. From this measurement the following limits on the anomalous γ\gammaWW gauge couplings are derived at 95\% CL: 3.6Δκγ1.5\rm -3.6 \Delta \kappa_\gamma 1.5 and 3.6λγ3.6\rm -3.6 \lambda_\gamma 3.6

    Fusion of Sensory Information, Internal Models, and Policy in Autonomic Computing Systems

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    Distributed Policy Conflict Analysis Using Information Models and Ontologies

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    The Policy Continuum – Policy Authoring and Conflict Analysis

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    The policy continuum is a fundamental component of any policy-based management implementation for autonomic networking, but as of yet has no formal operational semantics. We propose a policy continuum model and accompanying policy authoring process that demonstrates the key properties that set a continuum apart from a non-hierarchical policy model. As part of the policy authoring process we present a policy conflict analysis algorithm that leverages the information model, making it applicable to arbitrary applications and continuum levels. The approach for policy conflict analysis entails analysing a candidate policy (either newly created or modified) on a pair-wise basis with already deployed policies and potential conflicts between the policies are fed back to the policy author. Central to the approach is a two-phase algorithm which firstly determines the relationships between the pair of policies and secondly applies an application specific conflict pattern to determine if the policies should be flagged as potentially conflicting. In this paper we present the formal policy continuum and two-phase conflict analysis algorithm as part of the policy authoring process, we describe an implementation where we demonstrate the detection of potential conflicts within a policy continuum. (C) 2008 Elsevier B.V. All rights reserved.X1124sciescopu

    Conflict Prevention via Model-driven Policy Refinement, in Large Scale Management of Distributed Systems

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    On Harnessing Information Models and Ontologies for Policy Conflict Analysis

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