14,402 research outputs found
Feynman-Jackson integrals
We introduce perturbative Feynman integrals in the context of q-calculus
generalizing the Gaussian q-integrals introduced by Diaz and Teruel. We provide
analytic as well as combinatorial interpretations for the Feynman-Jackson
integrals.Comment: Final versio
Extraction of P11 Resonance from pi-N Data and Its Stability
An important question about resonance extraction is how much resonance poles
and residues extracted from data depend on a model used for the extraction, and
on the precision of data. We address this question with the dynamical
coupled-channel (DCC) model developed in Excited Baryon Analysis Center (EBAC)
at JLab. We focus on the P11 pi-N scattering. We examine the model-dependence
of the poles by varying parameters to a large extent within the EBAC-DCC model.
We find that two poles associated with the Roper resonance are fairly stable
against the variation. We also develop a model with a bare nucleon, thereby
examining the stability of the Roper poles against different analytic structure
of the P11 amplitude below pi-N threshold. We again find a good stability of
the Roper poles.Comment: 6 pages, 8 figures, Contribution to the proceedings of 24th
International Nuclear Physics Conference (INPC), Vancouver, Canada, 4-9 July
201
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Next-generation sequencing of dsRNA is greatly improved by treatment with the inexpensive denaturing reagent DMSO.
dsRNA is the genetic material of important viruses and a key component of RNA interference-based immunity in eukaryotes. Previous studies have noted difficulties in determining the sequence of dsRNA molecules that have affected studies of immune function and estimates of viral diversity in nature. DMSO has been used to denature dsRNA prior to the reverse-transcription stage to improve reverse transcriptase PCR and Sanger sequencing. We systematically tested the utility of DMSO to improve the sequencing yield of a dsRNA virus (Φ6) in a short-read next-generation sequencing platform. DMSO treatment improved sequencing read recovery by over two orders of magnitude, even when RNA and cDNA concentrations were below the limit of detection. We also tested the effects of DMSO on a mock eukaryotic viral community and found that dsRNA virus reads increased with DMSO treatment. Furthermore, we provide evidence that DMSO treatment does not adversely affect recovery of reads from a ssRNA viral genome (influenza A/California/07/2009). We suggest that up to 50 % DMSO treatment be used prior to cDNA synthesis when samples of interest are composed of or may contain dsRNA
Double and single pion photoproduction within a dynamical coupled-channels model
Within a dynamical coupled-channels model which has already been fixed from
analyzing the data of the pi N -> pi N and gamma N -> pi N reactions, we
present the predicted double pion photoproduction cross sections up to the
second resonance region, W< 1.7 GeV. The roles played by the different
mechanisms within our model in determining both the single and double pion
photoproduction reactions are analyzed, focusing on the effects due to the
direct gamma N -> pi pi N mechanism, the interplay between the resonant and
non-resonant amplitudes, and the coupled-channels effects. The model parameters
which can be determined most effectively in the combined studies of both the
single and double pion photoproduction data are identified for future studies.Comment: Version to appear in PRC. 16 pages, 13 figure
Catalogue of the morphological features in the Spitzer Survey of Stellar Structure in Galaxies (SG)
A catalogue of the morphological features for the complete Spitzer Survey of
Stellar Structure in Galaxies (SG), including 2352 nearby galaxies, is
presented. The measurements are made using 3.6 m images, largely tracing
the old stellar population; at this wavelength the effects of dust are also
minimal. The measured features are the sizes, ellipticities, and orientations
of bars, rings, ringlenses, and lenses. Measured in a similar manner are also
barlenses (lens-like structures embedded in the bars), which are not lenses in
the usual sense, being rather the more face-on counterparts of the boxy/peanut
structures in the edge-on view. In addition, pitch angles of spiral arm
segments are measured for those galaxies where they can be reliably traced.
More than one pitch angle may appear for a single galaxy. All measurements are
made in a human-supervised manner so that attention is paid to each galaxy. We
used isophotal analysis, unsharp masking, and fitting ellipses to measured
structures. We find that the sizes of the inner rings and lenses normalized to
barlength correlate with the galaxy mass: the normalized sizes increase toward
the less massive galaxies; it has been suggested that this is related to the
larger dark matter content in the bar region in these systems. Bars in the low
mass galaxies are also less concentrated, likely to be connected to the mass
cut-off in the appearance of the nuclear rings and lenses. We also show
observational evidence that barlenses indeed form part of the bar, and that a
large fraction of the inner lenses in the non-barred galaxies could be former
barlenses in which the thin outer bar component has dissolved.Comment: 17 pages, 12 figures, accepted for publication in A&
Life-Giving Migrations: Re-visioning the Mystery of God Through U.S. Hispanic Eyes
This essay reflects on the dangerous situations of human migrations as revelatory of a God-for-us. Drawing on key texts in the Old and New Testaments, the author explores how God’s migration across human landscapes can deepen our understanding of divine and human personhood. It concludes with a few practical reflections that address Latinos/as and their life-seeking migrations across U.S. borders
Dynamical coupled-channels analysis of 1H(e,e'pi)N reactions
We have performed a dynamical coupled-channels analysis of available
p(e,e'pi)N data in the region of W < 1.6 GeV and Q^2 < 1.45 (GeV/c)^2. The
channels included are gamma^* N, pi N, eta N, and pi pi N which has pi Delta,
rho N, and sigma N components. With the hadronic parameters of the model
determined in our previous investigations of pi N --> pi N, pi pi N reactions,
we have found that the available data in the considered W < 1.6 GeV region can
be fitted well by only adjusting the bare gamma^* N --> N^* helicity amplitudes
for the lowest N^* states in P33, P11, S11 and D13 partial waves. The
sensitivity of the resulting parameters to the amount of data included in the
analysis is investigated. The importance of coupled-channels effect on the
p(e,e' pi)N cross sections is demonstrated. The meson cloud effects, as
required by the unitarity conditions, on the gamma^* N --> N^* form factors are
also examined. Necessary future developments, both experimentally and
theoretically, are discussed.Comment: 14 pages, 11 figures. Version to appear in PR
Extraction of P11 resonances from pi N data
We show that two P11 nucleon resonance poles near the pi Delta threshold,
obtained in several analyses, are stable against large variations of parameters
within a dynamical coupled-channels analysis based on meson-exchange
mechanisms. By also performing an analysis based on a model with a bare nucleon
state, we find that this two-pole structure is insensitive to the analytic
structure of the amplitude in the region below pi N threshold. Our results are
M_pole = (1363^{+9}_{-6} -i79^{+3}_{-5}) MeV and (1373^{+12}_{-10}
-i114^{+14}_{-9}) MeV. We also demonstrate that the number of poles in the 1.5
GeV < W < 2 GeV region could be more than one, depending on how the structure
of the single-energy solution of SAID is fitted. For three-pole solutions, our
best estimated result of a pole near N(1710) listed by Particle Data Group is
(1829^{+131}_{-65} -i192^{+88}_{-110}) MeV which is close to the results of
several previous analyses. Our results indicate the need of more accurate pi N
reaction data in the W > 1.6 GeV region for high precision resonance
extractions.Comment: 15 pages, 4 figure
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