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A background-independent, Lorentz-covariant approach to compute conserved charges in odd-dimensional AdS gravity, alternative to the standard counterterms method, is presented. A set of boundary conditions on the asymptotic extrinsic and Lorentz curvature, rather than a Dirichlet boundary condition on the metric is used. With a given prescription of the boundary term, a well-defined action principle in any odd dimension is obtained. The same boundary term regularizes the Euclidean action and gives the correct black hole thermodynamics. The conserved charges are obtained from the asymptotic symmetries through Noether theorem without reference to any background. For topological AdS black holes the vacuum energy matches the expression conjectured by Emparan, Johnson and Myers \cite{Emparan-Johnson-Myers} for all odd dimensions., 5 pages, no figures, revtex

The quantization of the massless Thirring model in the light-cone using functional methods is considered. The need to compactify the coordinate $x^-$ in the light-cone spacetime implies that the quantum effective action for left-handed fermions contains excitations similar to abelian instantons produced by composite of left-handed fermions. Right-handed fermions don't have a similar effective action. Thus, quantum mechanically, chiral symmetry must be broken as a result of the topological excitations. The conserved charge associated to the topological states is quantized. Different cases with only fermionic excitations or bosonic excitations or both can occur depending on the boundary conditions and the value of the coupling., Comment: title changed, one reference added, accepted in Phys. Lett. B

It is pointed out that the action recently proposed by Ba\~nados et al. for gravitation in odd dimensions higher (and lower) than four, provides a natural quantization for the gravitational constant. These theories possess no dimensionful parameters and hence they may be power counting renormalizable., Comment: 9 pages, LaTeX

An innovative two-step route was successfully applied to the microwave-assisted synthesis of Pr–ZrSiO 4 , V–ZrSiO 4 and Cr–YAlO 3 ceramic pigments. It is able to reduce the total synthesis time from many hours down to a few minutes. Industrial batches were pelletized and underwent a short time pre-heating in conventional electric furnace (from 300 up to 1000 °C) prior to dielectric heating in microwave oven (2.45 GHz, 800 W continuous or paused). Pre-heating is necessary to reach a thermal level at which pigment precursors are activated under microwave irradiation (high enough tan δ of dielectric properties). Activation kinetics was followed by measuring (optical pyrometer) the external temperature of crucible during MW irradiation and the internal temperature at the end of heating process. Pigments were characterized by colourimetry (CIE Lab) and XRPD with Rietveld refinement. The V–ZrSiO 4 system is easily activated, already at pre-heating of 300 °C, with good reaction yield and colour performance; nevertheless it is difficult to keep under control, as temperatures exceeding 1200 °C are rapidly reached. The Pr–ZrSiO 4 system is activated after pre-heating over 600 °C and exhibits a slow kinetics, resulting in a low reaction yield and unsatisfactory colour. The Cr–YAlO 3 pigment is formed with colour and reaction yield close to those of the correspondent industrial product, even though after pre-heating at 800 °C or more. A peculiar behaviour of silica phases was observed in zircon systems, particularly after lower pre-heating temperatures. It consists in an early transformation of quartz (present as precursor) into cristobalite and abundant amorphous phase, before the SiO 2 + ZrO 2 → ZrSiO 4 transformation occurred.