We give an efficient method, combining number-theoretic and combinatorial ideas, to exactly compute black hole entropy in the framework of loop quantum gravity. Along the way we provide a complete characterization of the relevant sector of the spectrum of the area operator, including degeneracies, and explicitly determine the number of solutions to the projection constraint. We use a computer implementation of the proposed algorithm to confirm and extend previous results on the detailed structure of the black hole degeneracy spectrum. 相似文献
Sunto Si dimostra un teorema di punto unito per una classe abbastanza ampia di mappe plurivalenti con pesi fra gli ANR metrici. Questo teorema contiene tanto i classici teoremi di punto fisso di Eilenberg-Montgomery, O' Neill, Darbo come i risultati di connettività di insiemi di punti fissi di famiglie parametrizzate di mappe dovuti a Leray e Browder. 相似文献
Variation of the complex permeability with frequency of Ni1−xZnxFe2O4 (x=0.5, 0.6 and 0.7) prepared by a combustion method has been measured over a wide range of frequency, up to 1.8 GHz. Zn content improves permeability but moves the onset of resonance to lower frequencies.
The influence on some properties of samples prepared by the insertion of small amounts of Ruthenium, Yttrium and rare-earth cations into the Ni0.5Zn0.5MxFe2−xO4 ferrite has been also investigated. Relative losses and Curie temperature of all the samples have been measured. Ferrites substituted with Ru and Gd improve microwave behavior compared to non-substituted samples. 相似文献
In a recent article, we described a seismic inversion method for determining the crustal velocity and attenuation of basins in earthquake-prone regions. We formulated the problem as a constrained nonlinear least-squares optimization problem in which the constraints are the equations that describe the forward wave propagation. Here, we conduct a parametric study to investigate the influence of parameters such as the form of the regularization function, receiver density, preconditioning, noise level of the data, and the multilevel continuation technique on the cost and quality of the inversion. We use the same 2D Los Angeles example as in our earlier study. 相似文献
Towards cooler solid oxide fuel cells: Disorder and dimensionality (see picture) play an important role in determining ion mobility of bulk and artificially nanolayered materials and should be considered in the design of new electrolytes with enhanced conductivity.
We prove the existence of an unbounded connected branch of nontrivial homoclinic trajectories of a family of discrete nonautonomous asymptotically hyperbolic systems parametrized by a circle under assumptions involving topological properties of the asymptotic stable bundles. 相似文献
The structural analysis of strontium hexaferrites SrFexO19 (for x?=?12, 11 and 10) and substituted samples Sr0.7Nd0.3Fe12???yCo0.3O19 (for y?=?0.3,1.3 and 2.3) prepared through the citrate precursor method is shown. Nd and Co substitution modifies saturation magnetization (MS) and increases coercivity (Hc) in samples heat-treated at 1100°C for two hours. Mössbauer analyses show different iron occupancy and the influence of the Fe3?+? content is particularly emphasized. Hematite segregation is observed for some compositions. Samples with low Fe3?+? content show the best magnetic properties with no secondary phase segregation. 相似文献
We study the effects of noise on excitable DS found on nonlinear Kerr cavities, showing that the system exhibits coherence
resonance, characterized by a maximum degree of regularity for intermediate noise intensities. This behavior is observed for
two different ways of applying noise: an additive white uncorrelated spatio-temporal noise and including fluctuations in the
intensity
of an addressing beam. 相似文献
We introduce a notion of orientation of a Fredholm map on a given compact subset of its domain and show that various approaches
to orientation have as outcome the same class of orientable maps. 相似文献