12,426 research outputs found
Improving population-specific allele frequency estimates by adapting supplemental data: an empirical Bayes approach
Estimation of the allele frequency at genetic markers is a key ingredient in
biological and biomedical research, such as studies of human genetic variation
or of the genetic etiology of heritable traits. As genetic data becomes
increasingly available, investigators face a dilemma: when should data from
other studies and population subgroups be pooled with the primary data? Pooling
additional samples will generally reduce the variance of the frequency
estimates; however, used inappropriately, pooled estimates can be severely
biased due to population stratification. Because of this potential bias, most
investigators avoid pooling, even for samples with the same ethnic background
and residing on the same continent. Here, we propose an empirical Bayes
approach for estimating allele frequencies of single nucleotide polymorphisms.
This procedure adaptively incorporates genotypes from related samples, so that
more similar samples have a greater influence on the estimates. In every
example we have considered, our estimator achieves a mean squared error (MSE)
that is smaller than either pooling or not, and sometimes substantially
improves over both extremes. The bias introduced is small, as is shown by a
simulation study that is carefully matched to a real data example. Our method
is particularly useful when small groups of individuals are genotyped at a
large number of markers, a situation we are likely to encounter in a
genome-wide association study.Comment: Published in at http://dx.doi.org/10.1214/07-AOAS121 the Annals of
Applied Statistics (http://www.imstat.org/aoas/) by the Institute of
Mathematical Statistics (http://www.imstat.org
The THDM with the Inverse Seesaw Mechanisms
In this paper, we combine the -Two-Higgs-Doublet-Model (THDM) with
the inverse seesaw mechanisms. In this model, the Yukawa couplings involving
the sterile neutrinos and the exotic Higgs bosons can be of order one in the
case of a large . We calculated the corrections to the Z-resonance
parameters , , , together with the branching ratios, and the muon anomalous . Compared with the
current bounds and plans for the future colliders, we find that the corrections
to the electroweak parameters can be contrained or discovered in much of the
parameter space
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