5,042 research outputs found
Statistical Entropy of a BTZ Black Hole from Loop Quantum Gravity
We compute the statistical entropy of a BTZ black hole in the context of
three-dimensional Euclidean loop quantum gravity with a cosmological constant
. As in the four-dimensional case, a quantum state of the black hole
is characterized by a spin network state. Now however, the underlying colored
graph lives in a two-dimensional spacelike surface , and some
of its links cross the black hole horizon, which is viewed as a circular
boundary of . Each link crossing the horizon is colored by a
spin (at the kinematical level), and the length of the horizon is
given by the sum of the fundamental length contributions
carried by the spins of the links . We propose an
estimation for the number of the Euclidean BTZ
black hole microstates (defined on a fixed graph ) based on an analytic
continuation from the case to the case . In our model,
we show that reproduces the Bekenstein-Hawking
entropy in the classical limit. This asymptotic behavior is independent of the
choice of the graph provided that the condition
is satisfied, as it should be in three-dimensional quantum gravity.Comment: 14 pages. 1 figure. Paragraph added on page 7 to clarify the horizon
conditio
Hypersymmetry bounds and three-dimensional higher-spin black holes
We investigate the hypersymmetry bounds on the higher spin black hole
parameters that follow from the asymptotic symmetry superalgebra in higher-spin
anti-de Sitter gravity in three spacetime dimensions. We consider anti-de
Sitter hypergravity for which the analysis is most transparent. This is a
Chern-Simons theory which contains,
besides a spin- field, a spin- field and a spin- field. The
asymptotic symmetry superalgebra is then the direct sum of two-copies of the
hypersymmetric extension of , which contains
fermionic generators of conformal weight and bosonic generators of
conformal weight in addition to the Virasoro generators. Following standard
methods, we derive bounds on the conserved charges from the anticommutator of
the hypersymmetry generators. The hypersymmetry bounds are nonlinear and are
saturated by the hypersymmetric black holes, which turn out to possess
-hypersymmetry and to be "extreme", where extremality can be defined in
terms of the entropy: extreme black holes are those that fulfill the
extremality bounds beyond which the entropy ceases to be a real function of the
black hole parameters. We also extend the analysis to other -solitonic
solutions which are maximally (hyper)symmetric.Comment: 26 page
Combining absolute and relative information in studies on food quality
A common problem in food science concerns the assessment of the quality of food samples. Typically, a group of panellists is trained exhaustively on how to identify different quality indicators in order to provide absolute information, in the form of scores, for each given food sample. Unfortunately, this training is expensive and time-consuming. For this very reason, it is quite common to search for additional information provided by untrained panellists. However, untrained panellists usually provide relative information, in the form of rankings, for the food samples. In this paper, we discuss how both scores and rankings can be combined in order to improve the quality of the assessment
Achieving Very High PV Penetration
This article argues that optimally deployed intermittency solutions could affordably transform solar power generation into the firm power delivery system modern economies require, thereby enabling very high solar penetration and the displacement conventional power generation. The optimal deployment of these highâpenetration enabling solutions imply the existence of a healthy power grid, and therefore imply a central role for utilities and grid operators. This article also argues that a valueâbased electricity compensation mechanism, recognizing the multifaceted, penetrationâdependent value and cost of solar energy, and capable of shaping consumption patterns to optimally match resource and demand, would be an effective vehicle to enable high solar penetration and deliver affordable firm power generation
Aircraft conflict detection using data mining and statistical tools
Nowadays and taking into account the different indicators and the forecast of the air traffic volume from Eurocontrol, it is accepted the idea that the traffic will be doubled by 2030, that is why it is so important to find new and efficient methods which allow the infrastructure absorb such a huge demand. Hence the importance of designs a plan in order to increase the actual capacity. This is the example of ATM MASTER PLAN included inside SESAR (Single European Sky and Research). The main aim of this project is to test a different tool which could lead to detect conflicts on the airspace and find which is its performance compared to a traditional 4D forecast trajectory software. It will be entirely developed on the environment of Python and the Scikitlearn library will be used in order to make the machine learn which is a conflict situation and which not
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