Considerations on grapevine selection and certification

Different viruses and virus-like diseases can be detrimental to grapevines and their products. The protocols of the assays used to evaluate the impact of viruses have evolved with the progress of the knowledge in aetiology and diagnosis. A wrong interpretation of the data from experiments that compare the performance of virus-infected and non-infected vines may lead to erroneous conclusions. Even if some experiments show that virus infections induce an increase of sugar content, a better evaluation of the experimental data may show that the conclusion drawn is incorrect. The role viruses may play in clonal variability is also discussed

Multidomain switching in the ferroelectric nanodots

Controlling the polarization switching in the ferroelectric nanocrystals, nanowires and nanodots has an inherent specificity related to the emergence of depolarization field that is associated with the spontaneous polarization. This field splits the finite-size ferroelectric sample into polarization domains. Here, based on 3D numerical simulations, we study the formation of 180$^{\circ }$ polarization domains in a nanoplatelet, made of uniaxial ferroelectric material, and show that in addition to the polarized monodomain state, the multidomain structures, notably of stripe and cylindrical shapes, can arise and compete during the switching process. The multibit switching protocol between these configurations may be realized by temperature and field variations

Holographic renormalization and supersymmetry

Holographic renormalization is a systematic procedure for regulating divergences in observables in asymptotically locally AdS spacetimes. For dual boundary field theories which are supersymmetric it is natural to ask whether this defines a supersymmetric renormalization scheme. Recent results in localization have brought this question into sharp focus: rigid supersymmetry on a curved boundary requires specific geometric structures, and general arguments imply that BPS observables, such as the partition function, are invariant under certain deformations of these structures. One can then ask if the dual holographic observables are similarly invariant. We study this question in minimal N = 2 gauged supergravity in four and five dimensions. In four dimensions we show that holographic renormalization precisely reproduces the expected field theory results. In five dimensions we find that no choice of standard holographic counterterms is compatible with supersymmetry, which leads us to introduce novel finite boundary terms. For a class of solutions satisfying certain topological assumptions we provide some independent tests of these new boundary terms, in particular showing that they reproduce the expected VEVs of conserved charges

Nomenclature of grapevine leafroll-associated putative closteroviruses

Comparative immunoenzymatic (ELISA), immunoelectron microscopic (IEM) and immunoblotting tests were carried out with antisera produced in different laboratories and commercial diagnostic kits on closterolike viruses reported in the literature under the name of grapevine corky bark-associated virus (GCBaV) and grapevine leafroll-associated viruses IIa and IIb (GLRaV IIa and GLRaV IIb). The results of these studies have established that GCBaV is the same as GLRaV IIb and that both viruses are apparently identical to an isolate of GLRaV-2 identified in France, whose designation as the authentic GLRaV 2 is proposed. GLRaV IIa is serologically distinct from all known clostero-like viruses of the grapevine and, therefore, the provisional name of grapevine leafroll-associated Virus 6 (GLRaV-6) is suggested for it

Mealybug transmission of grapevine virus A

A closterovirus morphologially and serologically very close or identical to grapevine virus A (GVA) was experimentally transmitted by adults and instars of the Pseudococcidae mealybug Pseudococcus longispinus TARGIONI TOZZETTI from grapevine of cv. Inzolia affected by leafroll and stem pitting to Nicotiana clevelandii GRAY. GVA could not be recovered from infected vines by inoculation of sap but it was mechanically transmitted from N. clevelandii to N. benthamiana DOMIN. With immunosorbent electron microscopy (ISEM) tests, the presence of GVA was ascertained in: both the above herbaceous hosts;Inzolia vines used as donor plants for mealybug transmission tests;formerly virus-free Cabernet Franc and Procupac vines that had shown leafroll symptoms following natural mealybug infestation in a greenhouse where they were grown next to diseased grapes;squashed mealybugs which had fed on infected Inzolia vines.ISEM findings were confirmed by thin sectioning. In all cases filamentous virus particles were found in phloem tissues of infected herbaceous hosts and vines. In addition, donor (Inzolia) and recipient (Cabernet Franc, Procupac and LN-33) grapevines, but not herbaceous hosts, contained isometric virus-like particles and associated cytopathic structures (vesiculated bodies). The occurrence of a mixed infection in donor vines and the apparent transmission of both types of particles to grapevine does not allow to draw conclusions on the etiological significance of GVA in relation to leafroll disease. Further trials with source plants infected with GVA alone are now under way.Übertragung des Rebenvirus A durch SchildläuseEin Closterovirus, das morphologisch und serologisch dem Rebenvirus A (GVA) sehr nahesteht oder mit diesem identisch ist, wurde durch Adulte und Larven der Schildlaus Pseudococcus longispinus TARGIONI TOZZEITI (Pseudococcidae) von an Blattrollkrankheit und Holzrunzeligkeit erkrankten Reben der Sorte Inzolia auf Nicotiana clevelandii GRAY übertragen. Durch Saftübertragung aus infizierten Reben konnte GVA nicht nachgewiesen werden; es wurde jedoch von N. clevelandii auf N. bentamiana DOMIN. mechanisch übertragen. Mittels ISEM konnte GVA nachgewiesen werden: In den beiden oben genannten krautigen Wirtsarten;in Reben der Sorte Inzolia, die als Spenderpflanzen für die Schildlaus-Übertragungsversuche verwendet worden waren;in ursprünglich virusfreien Reben der Sorten Cabernet Franc und Procupac, die Blattrollsymptome gezeigt hatten, nachdem sie in einem Gewächshaus in unmittelbarer Nähe erkrankter Reben spontan von Schildläusen befallen worden waren;in zerquetschten Schildläusen, die an infizierten lnzolia-Reben gesogen hatten.Die ISEM-Befunde wurden an Dünnschnitten bestätigt. In allen Fällen wurden im Phloemgewebe der infizierten krautigen Wirtspflanzen und Reben filamentöse Viruspartikeln gefunden. Zusätzlich enthielten die Spender( Inzolia) und Empfängerreben (Cabernet Franc, Procupac und LN-33), nicht jedoch die krautigen Wirtspflanzen, isometrische virusartige Partikeln zusammen mit cytopathologischen Strukturen (vesiculäre Körper). Wegen des Vorliegens einer Mischinfektion in den Spenderreben und der offensichtlichen Übertragung beider Partikeltypen auf die Rebe ist es nicht möglich, Rückschlüsse auf die ätiologische Bedeutung von GVA im Verhältnis zur Blattrollkrankheit zu ziehen. Weitere Versuche unter Verwendung von Virusquellen, die nur mit GVA infiziert sind, wurden aufgenommen

Supersymmetric AdS_5 solutions of M-theory

We analyse the most general supersymmetric solutions of D=11 supergravity consisting of a warped product of five-dimensional anti-de-Sitter space with a six-dimensional Riemannian space M_6, with four-form flux on M_6. We show that M_6 is partly specified by a one-parameter family of four-dimensional Kahler metrics. We find a large family of new explicit regular solutions where M_6 is a compact, complex manifold which is topologically a two-sphere bundle over a four-dimensional base, where the latter is either (i) Kahler-Einstein with positive curvature, or (ii) a product of two constant-curvature Riemann surfaces. After dimensional reduction and T-duality, some solutions in the second class are related to a new family of Sasaki-Einstein spaces which includes T^{1,1}/Z_2. Our general analysis also covers warped products of five-dimensional Minkowski space with a six-dimensional Riemannian space.Comment: 40 pages. v2: minor changes, eqs. (2.22) and (D.12) correcte

Holographic renormalization and supersymmetry

Holographic renormalization is a systematic procedure for regulating divergences in observables in asymptotically locally AdS spacetimes. For dual boundary field theories which are supersymmetric it is natural to ask whether this defines a supersymmetric renormalization scheme. Recent results in localization have brought this question into sharp focus: rigid supersymmetry on a curved boundary requires specific geometric structures, and general arguments imply that BPS observables, such as the partition function, are invariant under certain deformations of these structures. One can then ask if the dual holographic observables are similarly invariant. We study this question in minimal N = 2 gauged supergravity in four and five dimensions. In four dimensions we show that holographic renormalization precisely reproduces the expected field theory results. In five dimensions we find that no choice of standard holographic counterterms is compatible with supersymmetry, which leads us to introduce novel finite boundary terms. For a class of solutions satisfying certain topological assumptions we provide some independent tests of these new boundary terms, in particular showing that they reproduce the expected VEVs of conserved charges.Comment: 70 pages; corrected typo

All supersymmetric solutions of minimal supergravity in six dimensions

A general form for all supersymmetric solutions of minimal supergravity in six dimensions is obtained. Examples of new supersymmetric solutions are presented. It is proven that the only maximally supersymmetric solutions are flat space, AdS_3 x S^3 and a plane wave. As an application of the general solution, it is shown that any supersymmetric solution with a compact horizon must have near-horizon geometry R^{1,1} x T^4, R^{1,1} x K3 or identified AdS_3 x S^3.Comment: 40 pages. v2: two references adde

A Note on Einstein Sasaki Metrics in D \ge 7

In this paper, we obtain new non-singular Einstein-Sasaki spaces in dimensions D\ge 7. The local construction involves taking a circle bundle over a (D-1)-dimensional Einstein-Kahler metric that is itself constructed as a complex line bundle over a product of Einstein-Kahler spaces. In general the resulting Einstein-Sasaki spaces are singular, but if parameters in the local solutions satisfy appropriate rationality conditions, the metrics extend smoothly onto complete and non-singular compact manifolds.Comment: Latex, 13 page