Supersymmetric AdS Backgrounds in String and M-theory

We first present a short review of general supersymmetric compactifications in string and M-theory using the language of G-structures and intrinsic torsion. We then summarize recent work on the generic conditions for supersymmetric AdS_5 backgrounds in M-theory and the construction of classes of new solutions. Turning to AdS_5 compactifications in type IIB, we summarize the construction of an infinite class of new Sasaki-Einstein manifolds in dimension 2k+3 given a positive curvature Kahler-Einstein base manifold in dimension 2k. For k=1 these describe new supergravity duals for N=1 superconformal field theories with both rational and irrational R-charges and central charge. We also present a generalization of this construction, that has not appeared elsewhere in the literature, to the case where the base is a product of Kahler-Einstein manifolds.Comment: LaTeX, 35 pages, to appear in the proceedings of the 73rd Meeting between Physicists and Mathematicians "(A)dS/CFT correspondence", Strasbourg, September 11-13, 200

Fivebranes Wrapped on SLAG Three-Cycles and Related Geometry

We construct ten-dimensional supergravity solutions corresponding to the near horizon limit of IIB fivebranes wrapping special Lagrangian three-cycles of constant curvature. The case of branes wrapping a three-sphere provides a gravity dual of pure N=2 super-Yang-Mills theory in D=3. The non-trivial part of the solutions are seven manifolds that admit two G_2 structures each of which is covariantly constant with respect to a different connection with torsion. We derive a formula for the generalised calibration for this general class of solutions. We discuss analogous aspects of the geometry that arises when fivebranes wrap other supersymmetric cycles which lead to Spin(7) and SU(N) structures. In some cases there are two covariantly constant structures and in others one.Comment: v2: 26 pages, 3 figures, 1 table. Section 7 slightly expanded, references adde

Sasaki-Einstein Metrics on S^2 x S^3

We present a countably infinite number of new explicit co-homogeneity one Sasaki-Einstein metrics on S^2 x S^3, in both the quasi-regular and irregular classes. These give rise to new solutions of type IIB supergravity which are expected to be dual to N=1 superconformal field theories in four-dimensions with compact or non-compact R-symmetry and rational or irrational central charges, respectively.Comment: 20 pages. v2: references added, typos corrected. v3: minor typos correcte

A New Infinite Class of Sasaki-Einstein Manifolds

We show that for every positive curvature Kahler-Einstein manifold in dimension 2n there is a countably infinite class of associated Sasaki-Einstein manifolds X_{2n+3} in dimension 2n+3. When n=1 we recover a recently discovered family of supersymmetric AdS_5 x X_5 solutions of type IIB string theory, while when n=2 we obtain new supersymmetric AdS_4 x X_7 solutions of D=11 supergravity. Both are expected to provide new supergravity duals of superconformal field theories.Comment: 12 pages. v2: minor typos corrected, comment on generalisation to product base manifold

ldentification of virus diseases of grapevine and production of disease-free plants

Der Nachweis von Rebvirosen und die Erzeugung virusfreien PflanzgutesIn dem vorliegenden Übersichtsbericht werden symptomatologische Probleme, der Virusnachweis mit Hilfe von krautigen Testpflanzen und Indikatorreben, serologische Nachweismethoden sowie die Möglichkeiten elektronenmikroskopischer Verfahren behandelt. Abschließend werden die bislang praktizierten Programme für die Erzeugung virusfreien Vermehrungsmaterials diskutiert

The viroses and virus-like diseases of the grapevine

A bibliographic report, 1979-198

Virus diseases of the grapevine in a Sicilian herbarium of the past century

Dried grapevine specimens, collected in Sicily between 1880 and 1886, and showing different morphological and chromatic modifications, were found in a herbarium established in 1830 by Dr. FRANCESCO MINA PALUMBO, a physician of Castelbuono (Palermo). On the basis of symptoms still visible on the specimens and of the herbarium's original explanatory notes, the diseased material was identified as being affected by fanleaf, yellow mosaic and leafroll.Rebvirosen in einem sizilianischen Herbarium aus dem letzten JahrhundertGetrocknete Exemplare von Reben, die zwischen 1880 und 1886 in Sizilien für ein von Dr. FRANCESCO MINA PALUMBO, einem Arzt aus Castelbuono (Palermo), begründetes Herbarium gesammelt worden waren, zeigten verschiedene morphologische und farbliche Modifikationen. Die noch sichtbaren Symptome an den Herbarexemplaren erlauben zusammen mit den erläuternden Originalnotizen eine Diagnose auf Befall durch Reisigkrankheit, Gelbmosaik und Blattrollkrankheit

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