Brane World in a Topological Black Hole Bulk

We consider a static brane in the background of a topological black hole, in arbitrary dimensions. For hyperbolic horizons, we find a solution only when the black hole mass assumes its minimum negative value. In this case, the tension of the brane vanishes, and the brane position coincides with the location of the horizon. For an elliptic horizon, we show that the massless mode of Randall-Sundrum is recovered in the limit of large black hole mass.Comment: Latex, 8 pages, v2: Additional references, to appear in MPL

Polyphenolic Characterisation of Vranac, Kratosija and Cabernet Sauvignon (Vitis vinifera L. cv.) Grapes and Wines from Different Vineyard Locations in Montenegro

In Montenegro, red wines are produced predominantly, and Vranac accounts for nearly 80% of thesewines, followed by Kratosija and Cabernet Sauvignon. In order to characterise polyphenols in red varieties,grapes were sampled from representative vineyards at harvest time during 2011 and 2012. The contentand distribution of extractable anthocyanins, low-molecular mass proanthocyanidins (LMP) and highmolecularmass proanthocyanidins (HMP) in the seeds and skins of the grape berries were evaluated byapplying a five-day extraction method using ethanol:water (12:88) as extraction solvent. On average, thehighest content of LMP (2 006 and 1 690 mg/kg of grape fresh mass in years 2011 and 2012 respectively),HMP (2 705 and 2 805 mg/kg in years 2011 and 2012 respectively) and anthocyanins (1 035 mg/kg in theyear 2011) was found in the Cabernet Sauvignon grapes. The highest content of anthocyanins (1 113 mg/kgin the year 2012) and the lowest content of LMP (1 103 and 846 mg/kg in years 2011 and 2012 respectively)was found in Vranac grapes. Kratosija grapes had the lowest anthocyanin content (456 and 517 mg/kg inyears 2011 and 2012 respectively), and levels of LMP were similar to Vranac. The percentage distributionsof LMP between skins and seeds were 34:66, 39:61 and 49:51, whereas the distributions of HMP betweenskins and seeds were 67:33, 62:38 and 64:36 for Vranac, Kratosija and Cabernet Sauvignon respectively.All varieties had more LMP in the seeds and more HMP in the skins of the grapes. The results obtained areimportant to better understand the polyphenolic potential of Montenegrin red grape varieties

The trace of the heat kernel on a compact hyperbolic 3-orbifold

The heat coefficients related to the Laplace-Beltrami operator defined on the hyperbolic compact manifold H^3/\Ga are evaluated in the case in which the discrete group \Ga contains elliptic and hyperbolic elements. It is shown that while hyperbolic elements give only exponentially vanishing corrections to the trace of the heat kernel, elliptic elements modify all coefficients of the asymptotic expansion, but the Weyl term, which remains unchanged. Some physical consequences are briefly discussed in the examples.Comment: 11 page

Aspects of hidden and manifest SL(2,R) symmetry in 2D near-horizon black-hole background

The invariance under unitary representations of the conformal group SL(2,R) of a quantum particle is rigorously investigated in two-dimensional spacetimes containing Killing horizons using DFF model. The limit of the near-horizon approximation is considered. If the Killing horizon is bifurcate the conformal symmetry is hidden, i.e. it does not arise from geometrical spacetime isometries, but the whole Hilbert space turns out to be an irreducible unitary representation of SL(2,R) and the time evolution is embodied in the unitary representation. In this case the symmetry does not depend on the mass of the particle and, if the representation is faithful, the conformal observable K shows thermal properties. If the Killing horizon is nonbifurcate the conformal symmetry is manifest, i.e. it arises from geometrical spacetime isometries. The SL(2,R) representation which arises from the geometry selects a hidden conformal representation. Also in that case the Hilbert space is an irreducible representation of SL(2,R) and the group conformal symmetries embodies the time evolution with respect to the local Killing time. However no thermal properties are involved. The conformal observable K gives rise to Killing time evolution of the quantum state with respect to another global Killing time present in the manifold. Mathematical proofs about the developed machinery are supplied and features of the operator H_g = -({d^2}/{dx^2})+ ({g}/{x^2}), with g=-1/4 are discussed. It is proven that a statement, used in the recent literature, about the spectrum of self-adjoint extensions of H_g is incorrect.Comment: 22 pages, 1 figure, latex 2e, some misprint corrected, a reference and a footnote adde

Constant Curvature Black Holes

Constant curvature black holes are constructed by identifying points in anti-de Sitter space. In n dimensions, the resulting topology is R^{n-1} * S_1, as opposed to the usual R^2 * S_{n-2} Schwarzschild black hole, and the corresponding causal structure is displayed by a (n-1)-dimensional picture, as opposed to the usual 2-dimensional Kruskal diagram. The five dimensional case, which can be embedded in a Chern-Simons supergravity theory, is analyzed in detail.Comment: New references added and some improvements in the presentation introduced, 5 pages, 2 eps figures, REVTe

Impact of Alternative Skin Contact Procedures on the Aroma Composition of White Wine

Zelen, Ribolla Gialla and Malvasia Istriana, grapes from the Vitis vinifera (L.) varieties, were subjectedto four processes involving grape skin contact. Fresh and fruity young wines were produced by adding6% or 12% grape berries, respectively, during alcoholic fermentation, freezing the pomace (Fp) and thefreezing whole grapes (Fg). Wine-free volatile aromatic compounds were determined using two extractiontechniques coupled to gas chromatography (GC). These aromatic compounds and wine standard chemicalparameters were compared to control wines produced without skin contact. Esters, higher alcohols,terpenes, volatile phenols and C6 alcohols proved to be the most important sensorial odorants in wines.Both the content of aromatic compounds and the odour activity values showed some positive effects fromskin contact. The freezing of the grapes and addition of 12% grape berries proved most effective forZelen and Malvasia Istriana, producing a more intensive fruity and floral odour, a less intensive solventodour and additional freshness. The same processes resulted only in additional fruitiness or a less intensivesolvent odour in Ribolla Gialla while the lowest concentrations of grape derived terpenes were achieved forthis variety. The three varieties were most affected by freezing processes. During the sensorial evaluation,the wines that had been subjected to skin contact were generally preferred to the control wines

The Wahlquist-Newman solution

Based on a geometrical property which holds both for the Kerr metric and for the Wahlquist metric we argue that the Kerr metric is a vacuum subcase of the Wahlquist perfect-fluid solution. The Kerr-Newman metric is a physically preferred charged generalization of the Kerr metric. We discuss which geometric property makes this metric so special and claim that a charged generalization of the Wahlquist metric satisfying a similar property should exist. This is the Wahlquist-Newman metric, which we present explicitly in this paper. This family of metrics has eight essential parameters and contains the Kerr-Newman-de Sitter and the Wahlquist metrics, as well as the whole Pleba\'nski limit of the rotating C-metric, as particular cases. We describe the basic geometric properties of the Wahlquist-Newman metric, including the electromagnetic field and its sources, the static limit of the family and the extension of the spacetime across the horizon.Comment: LaTeX, 18 pages, no figures. Accepted for publication in Phys. Rev.

Tunnelling Methods and Hawking's radiation: achievements and prospects

The aim of this work is to review the tunnelling method as an alternative description of the quantum radiation from black holes and cosmological horizons. The method is first formulated and discussed for the case of stationary black holes, then a foundation is provided in terms of analytic continuation throughout complex space-time. The two principal implementations of the tunnelling approach, which are the null geodesic method and the Hamilton-Jacobi method, are shown to be equivalent in the stationary case. The Hamilton-Jacobi method is then extended to cover spherically symmetric dynamical black holes, cosmological horizons and naked singularities. Prospects and achievements are discussed in the conclusions.Comment: Topical Review commissioned and accepted for publication by "Classical and Quantum Gravity". 101 pages; 6 figure

The horizon and its charges in the first order gravity

In this work the algebra of charges of diffeomorphisms at the horizon of generic black holes is analyzed within first order gravity. This algebra reproduces the algebra of diffeomorphisms at the horizon, (Diff(S^1)), without central extension

Gravitational collapse to toroidal, cylindrical and planar black holes

Gravitational collapse of non-spherical symmetric matter leads inevitably to non-static external spacetimes. It is shown here that gravitational collapse of matter with toroidal topology in a toroidal anti-de Sitter background proceeds to form a toroidal black hole. According to the analytical model presented, the collapsing matter absorbs energy in the form of radiation (be it scalar, neutrinos, electromagnetic, or gravitational) from the exterior spacetime. Upon decompactification of one or two coordinates of the torus one gets collapsing solutions of cylindrical or planar matter onto black strings or black membranes, respectively. The results have implications on the hoop conjecture.Comment: 6 pages, Revtex, modifications in the title and in the interpretation of some results, to appear in Physical Review