4,182 research outputs found
K-Inflation in Noncommutative Space-Time
The power spectra of the scalar and tensor perturbations in the
noncommutative k-inflation model are calculated in this paper. In this model,
all the modes created when the stringy space-time uncertainty relation is
satisfied are generated inside the sound/Hubble horizon during inflation for
the scalar/tensor perturbations. It turns out that a linear term describing the
noncommutative space-time effect contributes to the power spectra of the scalar
and tensor perturbations. Confronting the general noncommutative k-inflation
model with latest results from \textit{Planck} and BICEP2, and taking and
as free parameters, we find that it is well consistent with
observations. However, for the two specific models, i.e. the tachyon and DBI
inflation models, it is found that the DBI model is not favored, while the
tachyon model lies inside the contour, if the e-folds number is
assumed to be around .Comment: 9 pages, 2 figures. arXiv admin note: substantial text overlap with
arXiv:1404.016
Bayesian nonparametric tests via sliced inverse modeling
We study the problem of independence and conditional independence tests
between categorical covariates and a continuous response variable, which has an
immediate application in genetics. Instead of estimating the conditional
distribution of the response given values of covariates, we model the
conditional distribution of covariates given the discretized response (aka
"slices"). By assigning a prior probability to each possible discretization
scheme, we can compute efficiently a Bayes factor (BF)-statistic for the
independence (or conditional independence) test using a dynamic programming
algorithm. Asymptotic and finite-sample properties such as power and null
distribution of the BF statistic are studied, and a stepwise variable selection
method based on the BF statistic is further developed. We compare the BF
statistic with some existing classical methods and demonstrate its statistical
power through extensive simulation studies. We apply the proposed method to a
mouse genetics data set aiming to detect quantitative trait loci (QTLs) and
obtain promising results.Comment: 32 pages, 7 figure
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