836 research outputs found

    Sull'antagonismo in vivo ed in vitro di Acremonium byssoides, endofita in Vitis vinifera, nei confronti di Plasmopara viticola

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    Lo studio dell\u2019interazione fra Acremonium byssoides, Vitis vinifera e Plasmopara viticola, condotto nell\u2019ultimo decennio, ha evidenziato in vitro e in vivo l\u2019attivit\ue0 antagonistica dell\u2019ifomicete, endofita negli organi verdi di alcune cultivars di vite, nei confronti del patogeno. In particolare, \ue8 stato accertato che sospensioni conidiche, filtrati colturali, estratti grezzi e metaboliti di A. byssoides riducono sensibilmente la germinazione delle spore agamiche e gamiche di P. viticola, limitando la produzione di propaguli. Inoltre, l\u2019uso di un microscopio laser confocale e l\u2019impiego di un\u2019opportuna tecnica di decolorazione dei tessuti fogliari, seguita da colorazione di contrasto, ha consentito di visualizzare l\u2019ifomicete, latente nelle nervature di foglie sane e iperparassita dell\u2019oomicete in foglie infette. In queste ultime, infatti, A. byssoides, dopo aver prodotto metaboliti secondari tossici per P. viticola, ne invade e degrada micelio, rami sporangiofori e spore gamiche. Tale attivit\ue0 antagonistica, determinando il contenimento sia della diffusione che della sopravvivenza del patogeno, pu\uf2 assumere, quindi, un ruolo rilevante nella definizione di strategie di difesa biologica contro la peronospora della vite

    Structural changes of tissue samples exposed to low frequency electromagnetic field: A FT-IR absorbance study

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    In the present work, we report on a preliminary Fourier Transform Infrared (FT-IR) Absorbance study performed on different kind of rat tissues, such as kidney and heart, exposed to a "non-ionizing" radiation source at low frequency, in the range typical of micro-waves (300 MHz <v< 300 GHz). The data were collected in a wide wavenumber region, from 400 cm−1to 4000 cm−1. The comparison of the absorbance spectra in the case of the normal tissues with the irradiated ones has shown significant differences in the spectral features in accordance with the morphological analysis performed by the optical microscopy

    Naphthalenone polyketides produced by Neofusicoccum parvum , a fungus associated with grapevine Botriosphaeria dieback

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    A strain of Neofusicoccum parvum isolated from declining vines was pathogenic to grapevine cultivar Inzolia in Sicily. This strain produced some metabolites in liquid medium. Crude extract, through a bio-guided purification process, yielded four naphthalenone polyketides. They were identified by comparison with spectroscopic data and optical proprieties reported in literature as: (3S, 4S)-7-ethyl-3,4,8-trihydroxy-6-methoxy-3,4-dihydro-1-(2H)-naphthalenone, (3S*, 4S*)-3,4-dihydro-3,4,8-trihydroxy-7-(1-hydroxyethyl)-6-methoxy-1-(2H)-naphthalenone, (4S)-3,4-dihydro-4,8-dihydroxy-1-(2H)-naphthalenone, named botryosphaerones D and A, isosclerone, respectively, and (3S*,4S*)-3,4,5-trihydroxy-1-tetralone (1-4). Phytotoxic activity of the isolated compounds (1-4) was tested on grapevine leaves at using the leaf puncture assay. All tested compounds were phytotoxic, with botryosphaerone D showing the greatest activity. The phytotoxic effects decreased when treated leaves were exposed to light. All of the metabolites did not show in vitro antifungal activity against Diplodia seriata, Lasiodiplodia mediterranea, Neofusicoccum vitifusiforme, or Phytophthora citrophthora. This is the first report of in vitro production of botryosphaerones D and A, and 3,4,5-trihydroxy-1-tetralone by N. parvum

    Non-equilibrium Condensation Process in a Holographic Superconductor

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    We study the non-equilibrium condensation process in a holographic superconductor. When the temperature T is smaller than a critical temperature T_c, there are two black hole solutions, the Reissner-Nordstrom-AdS black hole and a black hole with a scalar hair. In the boundary theory, they can be regarded as the supercooled normal phase and the superconducting phase, respectively. We consider perturbations on supercooled Reissner-Nordstrom-AdS black holes and study their non-linear time evolution to know about physical phenomena associated with rapidly-cooled superconductors. We find that, for T<T_c, the initial perturbations grow exponentially and, eventually, spacetimes approach the hairy black holes. We also clarify how the relaxation process from a far-from-equilibrium state proceeds in the boundary theory by observing the time dependence of the superconducting order parameter. Finally, we study the time evolution of event and apparent horizons and discuss their correspondence with the entropy of the boundary theory. Our result gives a first step toward the holographic understanding of the non-equilibrium process in superconductors.Comment: 20 pages, 7 figure

    Botryosphaeriaceae species associated with diseased loquat trees in Italy and description of Diplodia rosacearum sp. nov

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    [EN] Loquat (Eriobotrya japonica) is a fruit tree cultivated in several countries in the Mediterranean region. A survey of a loquat orchard in Sicily ( Italy) revealed the presence of plants showing dieback symptoms and cankers with wedge-shaped necrotic sectors. Fungi from the genera Diplodia and Neofusicoccum were isolated from symptomatic plants. On the basis of morphological characters and DNA sequence data four species were identified, Neofusicoccum parvum, N. vitifusiforme, Diplodia seriata and a novel Diplodia species, which is here described as D. rosacearum sp. nov. Inoculation trials of loquat plants cv Sanfilipparo showed that N. parvum, D. seriata and D. rosacearum were pathogenic to this host. Although variability was observed between isolates, N. parvum and D. rosacearum were the most aggressive species.This research was supported by Servizio VII Fitosanitario Forestale del Dipartimento Regionale, Azienda Regionale Foreste Demaniali. Artur Alves acknowledges financing by European Funds through COMPETE and by National Funds through the Portuguese Foundation for Science and Technology (FCT) to the research unit CESAM (UID/AMB/50017/2013 - POCI-01-0145-FEDER-007638) and himself (FCT Investigator Programme - IF/00835/2013), and support by the Contributi avvio e sviluppo collaborazioni internazionali (CORI-2014), Visiting Professor Programme at the University of Palermo, Italy. The authors thank Dr. Giuseppe Lo Giudice for allowing carrying out the surveys in his loquat field.Giambra, S.; Piazza, G.; Alves, A.; Mondello, V.; Berbegal Martinez, M.; Armengol Fortí, J.; Burruano, S. (2016). Botryosphaeriaceae species associated with diseased loquat trees in Italy and description of Diplodia rosacearum sp. nov. Mycosphere (Online). 7(7):978-989. https://doi.org/10.5943/mycosphere/si/1b/9S9789897

    Early stage scaling in phase ordering kinetics

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    A global analysis of the scaling behaviour of a system with a scalar order parameter quenched to zero temperature is obtained by numerical simulation of the Ginzburg-Landau equation with conserved and non conserved order parameter. A rich structure emerges, characterized by early and asymptotic scaling regimes, separated by a crossover. The interplay among different dynamical behaviours is investigated by varying the parameters of the quench and can be interpreted as due to the competition of different dynamical fixed points.Comment: 21 pages, latex, 7 figures available upon request from [email protected]

    Relaxation and Coarsening Dynamics in Superconducting Arrays

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    We investigate the nonequilibrium coarsening dynamics in two-dimensional overdamped superconducting arrays under zero external current, where ohmic dissipation occurs on junctions between superconducting islands through uniform resistance. The nonequilibrium relaxation of the unfrustrated array and also of the fully frustrated array, quenched to low temperature ordered states or quasi-ordered ones, is dominated by characteristic features of coarsening processes via decay of point and line defects, respectively. In the case of unfrustrated arrays, it is argued that due to finiteness of the friction constant for a vortex (in the limit of large spatial extent of the vortex), the typical length scale grows as ℓs∼t1/2\ell_s \sim t^{1/2} accompanied by the number of point vortices decaying as Nv∼1/tN_v \sim 1/t . This is in contrast with the case that dominant dissipation occurs between each island and the substrate, where the friction constant diverges logarithmically and the length scale exhibits diffusive growth with a logarithmic correction term. We perform extensive numerical simulations, to obtain results in reasonable agreement. In the case of fully frustrated arrays, the domain growth of Ising-like chiral order exhibits the low-temperature behavior ℓq∼t1/zq\ell_q \sim t^{1/z_q}, with the growth exponent 1/zq1/z_q apparently showing a strong temperature dependence in the low-temperature limit.Comment: 9 pages, 5 figures, to be published in Phys. Rev.

    Scaling Model of Annihilation-Diffusion Kinetics for Charged Particles with Long-Range Interactions

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    We propose the general scaling model for the diffusio n-annihilation reaction A++A−⟶∅A_{+} + A_{-} \longrightarrow \emptyset with long-range power-law i nteractions. The presented scaling arguments lead to the finding of three different regimes, dep ending on the space dimensionality d and the long-range force power e xponent n. The obtained kinetic phase diagram agrees well with existing simulation data and approximate theoretical results.Comment: RevTEX, 7 pages, no figures, accepted to Physical Review
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