5,607 research outputs found
Efficient Numerical Evaluation of Feynman Integral
Feynman loop integrals are a key ingredient for the calculation of higher
order radiation effects, and are responsible for reliable and accurate
theoretical prediction. We improve the efficiency of numerical integration in
sector decomposition by implementing a quasi-Monte Carlo method associated with
the CUDA/GPU technique. For demonstration we present the results of several
Feynman integrals up to two loops in both Euclidean and physical kinematic
regions in comparison with those obtained from FIESTA3. It is shown that both
planar and non-planar two-loop master integrals in the physical kinematic
region can be evaluated in less than half a minute with
accuracy, which makes the direct numerical approach viable for precise
investigation of higher order effects in multi-loop processes, e.g. the
next-to-leading order QCD effect in Higgs pair production via gluon fusion with
a finite top quark mass.Comment: 8 pages, 5 figures, published in Chinese Physics
Dust in the Local Group
How dust absorbs and scatters starlight as a function of wavelength (known as
the interstellar extinction curve) is crucial for correcting for the effects of
dust extinction in inferring the true luminosity and colors of reddened
astrophysical objects. Together with the extinction spectral features, the
extinction curve contains important information about the dust size
distribution and composition. This review summarizes our current knowledge of
the dust extinction of the Milky Way, three Local Group galaxies (i.e., the
Small and Large Magellanic Clouds, and M31), and galaxies beyond the Local
Group.Comment: 21 pages, 11 figures; invited review article published in "LESSONS
FROM THE LOCAL GROUP -- A Conference in Honour of David Block and Bruce
Elmegreen" eds. Freeman, K.C., Elmegreen, B.G., Block, D.L. & Woolway, M.
(SPRINGER: NEW YORK), pp. 85-10
A statistical thin-tail test of predicting regulatory regions in the Drosophila genome
Background: The identification of transcription factor binding sites (TFBSs)
and cis-regulatory modules (CRMs) is a crucial step in studying gene
expression, but the computational method attempting to distinguish CRMs from
NCNRs still remains a challenging problem due to the limited knowledge of
specific interactions involved. Methods: The statistical properties of
cis-regulatory modules (CRMs) are explored by estimating the similar-word set
distribution with overrepresentation (Z-score). It is observed that CRMs tend
to have a thin-tail Z-score distribution. A new statistical thin-tail test with
two thinness coefficients is proposed to distinguish CRMs from non-coding
non-regulatory regions (NCNRs). Results: As compared with the existing
fluffy-tail test, the first thinness coefficient is designed to reduce
computational time, making the novel thin-tail test very suitable for long
sequences and large database analysis in the post-genome time and the second
one to improve the separation accuracy between CRMs and NCNRs. These two
thinness coefficients may serve as valuable filtering indexes to predict CRMs
experimentally. Conclusions: The novel thin-tail test provides an efficient and
effective means for distinguishing CRMs from NCNRs based on the specific
statistical properties of CRMs and can guide future experiments aimed at
finding new CRMs in the post-genome time.Comment: arXiv admin note: substantial text overlap with arXiv:1402.533
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