The mosaic leafhopper Orientus ishidae: host plants, spatial distribution, infectivity, and transmission of 16SrV phytoplasmas to vines

Orientus ishidae (Matsumura) is an Asian species introduced into Europe and recently associated with 16SrV phytoplasmas, related to grapevine “flavescence dorée”. Its life cycle, host plants, spatial distribution, infection and vector capability have been investigated in vine-growing areas of Piedmont, NW Italy. The spatial distribution of adults in vineyards was studied by applying interpolation methods to trap capture data. Insects were subject to molecular analyses to verify phytoplasma presence and identity. DNA extraction and PCR were made to detect 16SrV phytoplasmas. Transmission experiments were set up, using different sources for phytoplasma acquisition, and two plant species and an artificial diet for inoculation. Whole mount in situ hybridization was made to detect phytoplasmas in the salivary glands of adults. In the vineyard agro-ecosystem, 19 plant species (11 families), mainly broadleaf trees and shrubs, were recognized as host plants of the insect. Adults were more abundant on putative host plants than on grapevines, with a clear clustering at the edges of vineyards, and without a massive intrusion into the vineyard from outside. 16SrV phytoplasmas were detected only in adults captured with yellow sticky traps (20 out of 188 tested). The transmission of 16SrV phytoplasmas was successful after phytoplasma acquisition from infected broad bean and inoculation on grapevine

Comunità microbica associata a Hyalesthes obsoletus Signoret, vettore del Legno nero della vite

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Applying and validating the PTVA-3 Model at the Aeolian Islands, Italy: assessment of the vulnerability of buildings to tsunamis

The volcanic archipelago of the Aeolian Islands (Sicily, Italy) is included on the UNESCO World Heritage list and is visited by more than 200 000 tourists per year. Due to its geological characteristics, the risk related to volcanic and seismic activity is particularly high. Since 1916 the archipelago has been hit by eight local tsunamis. The most recent and intense of these events happened on 30 December 2002. It was triggered by two successive landslides along the north-western side of the Stromboli volcano (Sciara del Fuoco), which poured approximately 2–3×10<sup>7</sup> m<sup>3</sup> of rocks and debris into the Tyrrhenian Sea. The waves impacted across the whole archipelago, but most of the damage to buildings and infrastructures occurred on the islands of Stromboli (maximum run-up 11 m) and Panarea. <br><br> The aim of this study is to assess the vulnerability of buildings to damage from tsunamis located within the same area inundated by the 2002 event. The assessment is carried out by using the PTVA-3 Model (Papathoma Tsunami Vulnerability Assessment, version 3). The PTVA-3 Model calculates a Relative Vulnerability Index (RVI) for every building, based on a set of selected physical and structural attributes. Run-up values within the area inundated by the 2002 tsunami were measured and mapped by the Istituto Italiano di Geofisica e Vulcanologia (INGV) and the University of Bologna during field surveys in January 2003. Results of the assessment show that if the same tsunami were to occur today, 54 buildings would be affected in Stromboli, and 5 in Panarea. The overall vulnerability level obtained in this analysis for Stromboli and Panarea are "average"/"low" and "very low", respectively. Nonetheless, 14 buildings in Stromboli are classified as having a "high" or "average" vulnerability. For some buildings, we were able to validate the RVI scores calculated by the PTVA-3 Model through a qualitative comparison with photographs taken by INGV and the University of Bologna during the post-tsunami survey. With the exception of a single structure, which is partially covered by a coastal dune on the seaward side, we found a good degree of accuracy between the PTVA-3 Model forecast assessments and the actual degree of damage experienced by buildings. This validation of the model increases our confidence in its predictive capability. Given the high tsunami risk for the archipelago, our results provide a framework for prioritising investments in prevention measures and addressing the most relevant vulnerability issues of the built environment, particularly on the island of Stromboli

Surfactant-like Effect and Dissolution of Ultrathin Fe Films on Ag(001)

The phase immiscibility and the excellent matching between Ag(001) and Fe(001) unit cells (mismatch 0.8 %) make Fe/Ag growth attractive in the field of low dimensionality magnetic systems. Intermixing could be drastically limited at deposition temperatures as low as 140-150 K. The film structural evolution induced by post-growth annealing presents many interesting aspects involving activated atomic exchange processes and affecting magnetic properties. Previous experiments, of He and low energy ion scattering on films deposited at 150 K, indicated the formation of a segregated Ag layer upon annealing at 550 K. Higher temperatures led to the embedding of Fe into the Ag matrix. In those experiments, information on sub-surface layers was attained by techniques mainly sensitive to the topmost layer. Here, systematic PED measurements, providing chemical selectivity and structural information for a depth of several layers, have been accompanied with a few XRD rod scans, yielding a better sensitivity to the buried interface and to the film long range order. The results of this paper allow a comparison with recent models enlightening the dissolution paths of an ultra thin metal film into a different metal, when both subsurface migration of the deposit and phase separation between substrate and deposit are favoured. The occurrence of a surfactant-like stage, in which a single layer of Ag covers the Fe film is demonstrated for films of 4-6 ML heated at 500-550 K. Evidence of a stage characterized by the formation of two Ag capping layers is also reported. As the annealing temperature was increased beyond 700 K, the surface layers closely resembled the structure of bare Ag(001) with the residual presence of subsurface Fe aggregates.Comment: 4 pages, 3 figure

Controlled Anisotropic Deformation of Ag Nanoparticles by Si Ion Irradiation

The shape and alignment of silver nanoparticles embedded in a glass matrix is controlled using silicon ion irradiation. Symmetric silver nanoparticles are transformed into anisotropic particles whose larger axis is along the ion beam. Upon irradiation, the surface plasmon resonance of symmetric particles splits into two resonances whose separation depends on the fluence of the ion irradiation. Simulations of the optical absorbance show that the anisotropy is caused by the deformation and alignment of the nanoparticles, and that both properties are controlled with the irradiation fluence.Comment: Submitted to Phys. Rev. Lett. (October 14, 2005

Optical absorption and photoluminescence spectroscopy of the growth of silver nanoparticles

Results obtained from the optical absorption and photoluminescence (PL) spectroscopy experiments have shown the formation of excitons in the silver-exchanged glass samples. These findings are reported here for the first time. Further, we investigate the dramatic changes in the photoemission properties of the silver-exchanged glass samples as a function of postannealing temperature. Observed changes are thought to be due to the structural rearrangements of silver and oxygen bonding during the heat treatments of the glass matrix. In fact, photoelectron spectroscopy does reveal these chemical transformations of silver-exchanged soda glass samples caused by the thermal effects of annealing in a high vacuum atmosphere. An important correlation between temperature-induced changes of the PL intensity and thermal growth of the silver nanoparticles has been established in this Letter through precise spectroscopic studies.Comment: 15 pages,4 figures,PDF fil

Noise reduction in muon tomography for detecting high density objects

The muon tomography technique, based on multiple Coulomb scattering of cosmic ray muons, has been proposed as a tool to detect the presence of high density objects inside closed volumes. In this paper a new and innovative method is presented to handle the density fluctuations (noise) of reconstructed images, a well known problem of this technique. The effectiveness of our method is evaluated using experimental data obtained with a muon tomography prototype located at the Legnaro National Laboratories (LNL) of the Istituto Nazionale di Fisica Nucleare (INFN). The results reported in this paper, obtained with real cosmic ray data, show that with appropriate image filtering and muon momentum classification, the muon tomography technique can detect high density materials, such as lead, albeit surrounded by light or medium density material, in short times. A comparison with algorithms published in literature is also presented

Study of the bacterial community affiliated to Hyalesthes obsoletus, the insect vector of “bois noir” phytoplasma of grape

Grape yellows caused by phytoplasmas afflict several important wine-producing areas of Europe. A grape yellows with increasingincidence in European vineyards is “bois noir” (BN), caused by ‘Candidatus Phytoplasma solani’. Its vector is the planthopperHyalesthes obsoletus Signoret (Hemiptera Cixiidae), occasionally feeding on grapevine. An innovative strategy for reducing thediffusion of the disease could be symbiotic control, exploiting the action of symbiotic microorganisms of the insect host. To investigatethe occurrence of possible microbial candidates for symbiotic control we performed a molecular characterization of thebacteria associated to H. obsoletus. Length heterogeneity PCR was applied for a preliminary population screening. Taxonomicaffiliations of the bacterial species were analyzed by denaturing gradient gel electrophoresis, showing, within the microbial diversity,the intracellular reproductive parasite Wolbachia pipientis and a Bacteroidetes symbiont with 92% nt identity with ‘CandidatusSulcia muelleri’. PCR essays specific for these bacteria showed they co-localize in several organs of H. obsoletus. Fluorescentin situ hybridization was performed to assess the distribution of these microorganisms within the insect body, showing interestinglocalization patterns, particularly in insect gonads and salivary glands. These results could be a starting point for a deeper investigationof functions and relationships between microbial species

Precision measurements of Linear Scattering Density using Muon Tomography

We demonstrate that muon tomography can be used to precisely measure the properties of various materials. The materials which have been considered have been extracted from an experimental blast furnace, including carbon (coke) and iron oxides, for which measurements of the linear scattering density relative to the mass density have been performed with an absolute precision of 10%. We report the procedures that are used in order to obtain such precision, and a discussion is presented to address the expected performance of the technique when applied to heavier materials. The results we obtain do not depend on the specific type of material considered and therefore they can be extended to any application.Comment: 16 pages, 4 figure