10,663 research outputs found
Recent progress on the notion of global hyperbolicity
Global hyperbolicity is a central concept in Mathematical Relativity. Here,
we review the different approaches to this concept explaining both, classical
approaches and recent results. The former includes Cauchy hypersurfaces, naked
singularities, and the space of the causal curves connecting two events. The
latter includes structural results on globally hyperbolic spacetimes, their
embeddability in Lorentz-Minkowski, and the recently revised notions of both,
causal and conformal boundaries. Moreover, two criteria for checking global
hyperbolicity are reviewed. The first one applies to general splitting
spacetimes. The second one characterizes accurately global hyperbolicity and
spacelike Cauchy hypersurfaces for standard stationary spacetimes, in terms of
a naturally associated Finsler metric.Comment: 18 pages, 1 figure. Extended and updated contribution to the meeting
"New Developments in Lorentzian Geometry" Berlin, Nov. 200
Multiple hypothesis testing and clustering with mixtures of non-central t-distributions applied in microarray data analysis
Multiple testing analysis, based on clustering methodologies, is usually applied in Microarray Data Analysis for comparisons between pair of groups. In this paper, we generalize this methodology to deal with multiple comparisons among more than two groups obtained from microarray expressions of genes. Assuming normal data, we define a statistic which depends on sample means and sample variances, distributed as a non-central t-distribution. As we consider multiple comparisons among groups, a mixture of non-central t-distributions is derived. The estimation of the components of mixtures is obtained via a Bayesian approach, and the model is applied in a multiple comparison problem from a microarray experiment obtained from gorilla, bonobo and human cultured fibroblasts.Clustering, MCMC computation, Microarray analysis, Mixture distributions, Multiple hypothesis testing, Non-central t-distribution
Coherence of the posterior predictive p-value based on the posterior odds.
^aIt is well-known that classical p-values sometimes behave
incoherently for testing hypotheses in the sense that, when
, the support given to
is greater than or equal to the support given to
. This problem is also found for posterior
predictive p-values (a Bayesian-motivated alternative to classical
p-values). In this paper, it is proved that, under some conditions,
the posterior predictive p-value based on the posterior odds is
coherent, showing that the choice of a suitable discrepancy variable
is crucial
MOND's acceleration scale as a fundamental quantity
Some quantum-cosmic scaling relations indicate that the MOND acceleration
parameter a_0 could be a fundamental quantity ruling the self-gravitating
structures, ranging from stars and globular clusters up to superclusters of
galaxies and the whole observed universe. We discuss such coincidence relations
starting from the Dirac quantization condition ruling the masses of primordial
black holes.Comment: 6 page
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