252 research outputs found
Armillaria root rot on highbush blueberry (Vaccinium corymbosum L.) in north-eastern Italy (Trentino region)
No full textIon and electron local transport inside Single Helicity islands in the Reversed Field Pinch
No full textThe ion and electron diffusion coefficients inside the helical magnetic core in a single helicity reversed field pinch (RFP) toroidal plasma have been numerical determined by a Monte Carlo test particle approach. A new algorithm aimed at approximating with polyhedra the magnetic surfaces obtained with Poincaré cross sections has been developed. Stationary simulations of test ion and electron transport have been performed: they allow the determination of the average diffusion coefficients inside the helical core both for ions and electrons, which are much lower than those found in standard multiple helicity plasmas. Results are discussed and compared with those found in previous RFP simulations. The technique may be relevant also for stellarator and tokamak studies
Prima relazione dell'infezione radicale da Armillaria sul mirtillo alto fusto (Vaccinium corymbosum L.) in Trentino
No full textFirst report of Armillaria root rot on highbush blueberry (Vaccinium corymbosum L.) in north-eastern Italy (Trentino region)
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Microhabitat distributions and species interactions of ectoparasites on the gills of cichlid fish in Lake Victoria, Tanzania
No full textHeterogeneous exposure to parasites may contribute to host species differentiation. Hosts often harbour multiple parasite species which may interact and thus modify each other's effects on host fitness. Antagonistic or synergistic interactions between parasites may be detectable as niche segregation within hosts. Consequently, the within-host distribution of different parasite taxa may constitute an important axis of infection variation among host populations and species. We investigated the microhabitat distributions and species interactions of gill parasites (four genera) infecting 14 sympatric cichlid species in Lake Victoria, Tanzania. We found that the two most abundant ectoparasite genera (the monogenean Cichlidogyrus spp. and the copepod Lamproglena monodi) were non-randomly distributed across the host gills and their spatial distribution differed between host species. This may indicate microhabitat selection by the parasites and cryptic differences in the host-parasite interaction among host species. Relationships among ectoparasite genera were synergistic: the abundances of Cichlidogyrus spp. and the copepods L. monodi and Ergasilus lamellifer tended to be positively correlated. In contrast, relationships among morphospecies of Cichlidogyrus were antagonistic: the abundances of morphospecies were negatively correlated. Together with niche overlap, this suggests competition among morphospecies of Cichlidogyrus. We also assessed the reproductive activity of the copepod species (the proportion of individuals carrying egg clutches), as it may be affected by the presence of other parasites and provide another indicator of the species specificity of the host-parasite relationship. Copepod reproductive activity did not differ between host species and was not associated with the presence or abundance of other parasites, suggesting that these are generalist parasites, thriving in all cichlid species examined from Lake Victoria.sponsorship: This research was funded by the Swiss National Science Foundation and the University of Groningen, the Netherlands (Ubbo Emmius Programme). Infrastructure was provided by the Natural History Museum in Lugano, Switzerland and Hasselt University, Belgium (EMBRC Belgium -FWO project GOH3817N). We acknowledge Antoine Pariselle for help with identification of parasites belonging to Cichlidogyrus. (Swiss National Science Foundation, University of Groningen, the Netherlands (Ubbo Emmius Programme), Natural History Museum in Lugano, Switzerland, Hasselt University, Belgium (EMBRC Belgium - FWO project)|GOH3817N)status: Published onlin
Resonance between passing fast ions and MHD instabilities both in the tokamak and the RFP configurations
No full textFilamentary structures are observed during edge relaxation events associated with spontaneous enhanced confinement periods in the Madison Symmetric Torus reversed-field pinch (Dexter R.N., Kerst D.W., Lovell T.W., Prager S.C. and Sprott J.C. 1991 Fusion Technol. 19 131). The spatiotemporal shape of these structures is measured through extended toroidal and poloidal arrays of high-frequency magnetic probes at the plasma boundary. A simple model is used to interpret these structures as field-aligned current filaments, which are born at the reversal surface and propagate in the toroidal direction. The results found in MST share interesting commonalities with recent observations of filaments made during edge-localized modes in tokamaks and spherical tokamaks, as far as typical time scales, spatial localization and particle transport are concerned. Moreover, the dynamo effect produced by these events is estimated and compared with that produced during sawteeth. Though a single event has a small impact, the cumulative contribution of many of them produces a significant dynamo effect
High-Throughput preliminary screening of microorganisms with potential activity against Plasmopara viticola by means of quantitative Real-Time Polymerase Chain Reaction
No full textPerturbative transport studies in the reversed-field pinch
No full textIn this paper we present the results of transient transport experiments in a reversed-field pinch device. Measurements have been made in the Madison Symmetric Torus experiment using a novel soft x-ray diagnostic. Spontaneous transient transport events are observed in enhanced confinement shots obtained using the pulsed parallel current drive technique, as a consequence of bursts of magnetic fluctuations triggered by an edge resonant m = 0 instability. The perturbed electron heat diffusivity, chi(e), is estimated through a numerical transient heat transport model, and the values thus obtained are compared with those measured in similar unperturbed enhanced confinement and standard plasmas using the power balance technique
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