2,092 research outputs found

    The α\alpha Dynamo Effects in Laboratory Plasmas

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    A concise review of observations of the α\alpha dynamo effect in laboratory plasmas is given. Unlike many astrophysical systems, the laboratory pinch plasmas are driven magnetically. When the system is overdriven, the resultant instabilities cause magnetic and flow fields to fluctuate, and their correlation induces electromotive forces along the mean magnetic field. This α\alpha-effect drives mean parallel electric current, which, in turn, modifies the initial background mean magnetic structure towards the stable regime. This drive-and-relax cycle, or the so-called self-organization process, happens in magnetized plasmas in a time scale much shorter than resistive diffusion time, thus it is a fast and unquenched dynamo process. The observed α\alpha-effect redistributes magnetic helicity (a measure of twistedness and knottedness of magnetic field lines) but conserves its total value. It can be shown that fast and unquenched dynamos are natural consequences of a driven system where fluctuations are statistically either not stationary in time or not homogeneous in space, or both. Implications to astrophysical phenomena will be discussed.Comment: 21 pages, 15 figures, submitted to Magnetohydrodynamic

    Management of Dravet syndrome and emerging therapy options

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    Introduction: Dravet syndrome is an early onset epileptic and genetic encephalopathy. Although a well-recognised electroclinical picture is key to diagnosis, a mutation in the SCN1A gene is found in excess of 80%. In general prognosis is poor overall for seizure control and neurodevelopment. With careful phenotyping of the condition and review of treatment response we have become aware of the antiepileptic drugs that are most likely to help, but more importantly drugs that may lead to deterioration and consequently to avoid. Despite this, a significant number of children continue to have seizures and there is little evidence to suggest that we have substantially changed the prognosis in these patients. Areas covered: This review explores current views on the diagnosis and treatment of Dravet syndrome. Consideration is given to the underlying genetics, as well as agents proving to be useful in the management of seizures, including those currently under trial. This has been prepared utilising a review of current literature, as well as expert opinion. Expert opinion: Considerable experience in the field has led to a knowledge of optimised treatment in this condition. This involves both acute and maintenance treatment. Despite this, there has been little impact on overall outcomes. Newer treatments now provide promise with regard to seizure control; whether this will have an impact on overall outcome remains to be seen

    De Novo Genome Sequence of "Candidatus Liberibacter solanacearum" from a Single Potato Psyllid in California.

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    The draft genome sequence of "Candidatus Liberibacter solanacearum" strain RSTM from a potato psyllid (Bactericera cockerelli) in California is reported here. The RSTM strain has a genome size of 1,286,787 bp, a G+C content of 35.1%, 1,211 predicted open reading frames (ORFs), and 43 RNA genes

    Risk Analyses and Risk Management - Slope Instabilities in Alpine Environments

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    Two prominent deep-seated gravitational slope deformations in the Eastern Alps (Tyrol, Austria) have been activated in the last seven years and pose serious threats to the densely populated valleys. Based on multidisciplinary field investigations, different hazard scenarios of slope failures have been evaluated for risk management processes. These event scenarios, which are characterised by strongly varying volumes of the failing slide masses as well as by different probabilities of occurrence, and varying disintegration factors control different accumulation and damage scenarios. Finally, these evaluations and risk analyses aimed to define “design events”, i.e. which scenarios are relevant for the dimensioning of mitigation measures. The main aim is to sustainably enable further land use, in comparison to the overall geohazard risks that are also present at several other sites in Tyrol (Austria)

    Cultural differences in intimacy: The influence of gender-role ideology and individualism-collectivism

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    Two studies examined emotional intimacy in European Canadian and Chinese Canadian dating relationships. Cultural differences in gender-role ideology and individualism–collectivism were hypothesized to differentially contribute to selfdisclosure and responsiveness, and in turn, intimacy. Study 1 revealed that Chinese Canadians’ lower intimacy relative to European Canadians was mediated by their greater gender-role traditionalism but not by their individualism or collectivism. Study 2 further linked greater gender-role traditionalism to lower self-disclosure, and in turn, lower intimacy. Results also revealed that Chinese Canadians’ lower intimacy mediated their lower relationship satisfaction and higher rate of relationship termination in Study 1, but that Chinese Canadians were not any more likely to terminate their relationships in Study 2

    Saturation of Magnetorotational Instability through Magnetic Field Generation

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    The saturation mechanism of Magneto-Rotational Instability (MRI) is examined through analytical quasilinear theory and through nonlinear computation of a single mode in a rotating disk. We find that large-scale magnetic field is generated through the alpha effect (the correlated product of velocity and magnetic field fluctuations) and causes the MRI mode to saturate. If the large-scale plasma flow is allowed to evolve, the mode can also saturate through its flow relaxation. In astrophysical plasmas, for which the flow cannot relax because of gravitational constraints, the mode saturates through field generation only.Comment: 9 pages, 10 figures to appear in ApJ, Jun 2009, 10 v69

    Methyl group dynamics in a confined glass

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    We present a neutron scattering investigation on methyl group dynamics in glassy toluene confined in mesoporous silicates of different pore sizes. The experimental results have been analysed in terms of a barrier distribution model, such a distribution following from the structural disorder in the glassy state. Confinement results in a strong decreasing of the average rotational barrier in comparison to the bulk state. We have roughly separated the distribution for the confined state in a bulk-like and a surface-like contribution, corresponding to rotors at a distance from the pore wall respectively larger and smaller than the spatial range of the interactions which contribute to the rotational potential for the methyl groups. We have estimated a distance of 7 Amstrong as a lower limit of the interaction range, beyond the typical nearest-neighbour distance between centers-of-mass (4.7 Amstrong).Comment: 5 pages, 3 figures. To be published in European Physical Journal E Direct. Proceedings of the 2nd International Workshop on Dynamics in Confinemen

    Nuclear Fusion Power – An Overview of History, Present and Future

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