489 research outputs found
Genetic parameters and genomic regions associated with piglet response to vaccination for porcine reproductive and respiratory syndrome (PRRS) virus and co-infection with PRRS virus and porcine circovirus type 2b (PCV2b)
Citation: Dunkelberger, J. R., Serao, N. V. L., Kerrigan, M. A., Lunney, J. K., Rowland, R. R. R., & Dekkers, J. C. M. (2016). Genetic parameters and genomic regions associated with piglet response to vaccination for porcine reproductive and respiratory syndrome (PRRS) virus and co-infection with PRRS virus and porcine circovirus type 2b (PCV2b). Journal of Animal Science, 94, 52-53. doi:10.2527/msasas2016-112Objectives of this research were to estimate genetic parameters and to identify genomic regions associated with PRRS viral load (VL), PCV2b VL, and average daily gain (ADG) in nursery pigs vaccinated or non-vaccinated for PRRS virus (PRRSV), followed by co-infection with PRRSV and PCV2b. Data used included 396 commercial crossbred pigs from two PRRS Host Genetics Consortium trials, all from the same genetic supplier. Pigs were sent to Kansas State University after weaning and randomly sorted into two rooms. All pigs in one room were vaccinated for PRRS, and 28 d later, pigs in both rooms were co-infected with PRRSV and PCV2b, followed for 42 d, and genotyped using the 80K BeadChip. PRRS VL after vaccination and post co-infection and PCV2b VL were calculated as area under the curve of serum viremia from ?28 to 0, 0 to 21, and 0 to 42 d post co-infection, respectively. Genetic parameters were estimated by fitting multivariate animal models in ASReml4 with litter and pen (trial) as additional random effects. Trait-specific fixed effects of trial and weight and age at vaccination were also fitted. Genome-wide association (GWA) studies were performed by fitting SNPs as fixed effects one at a time in bivariate animal models for the non-vaccinated (Non-Vx) and vaccinated (Vx) groups for each trait. Heritability estimates following vaccination were 0.31, 0.07, and 0.10 for ADG Non-Vx, ADG Vx, and PRRS Vx, respectively. During the co-infection period, heritability estimates were slightly higher at 0.53, 0.57, 0.56, 0.20, 0.18, and 0.15 for ADG Non-Vx, ADG Vx, PRRS Non-Vx, PRRS Vx, PCV2b Non-Vx, and PCV2b Vx, respectively. Standard errors ranged from 0.14 to 0.22. A strong, positive genetic correlation (0.95 ± 1.01) was observed for PRRS VL post-vaccination with PRRS VL Non-Vx. Unique genomic regions were identified between Vx and Non-Vx pigs for each trait, the most significant of which was identified for PCV2b VL and located near the major histocompatibility complex, an important region for response to infection. The chromosome 4 region, which has been associated with VL following PRRSV-only infection, was associated with PRRS VL Non-Vx but not PRRS Vx or PRRS VL post-vaccination. Together, these results suggest that selection for improved performance under co-infection of PRRS and PCV2b is possible. Additionally, identification of unique genomic regions between Vx and Non-Vx pigs may enable selection of pigs with better response to vaccination. This research was supported by USDA-NIFA grants 2012–38420–19286 and 2013–68004–20362
Measurements of and Production in + Collisions at = 200 GeV
We report measurements of charmed-hadron (, ) production cross
sections at mid-rapidity in + collisions at a center-of-mass energy of
200 GeV by the STAR experiment. Charmed hadrons were reconstructed via the
hadronic decays , and their charge conjugates,
covering the range of 0.62.0 GeV/ and 2.06.0 GeV/ for
and , respectively. From this analysis, the charm-pair production cross
section at mid-rapidity is = 170 45
(stat.) (sys.) b. The extracted charm-pair cross section is
compared to perturbative QCD calculations. The transverse momentum differential
cross section is found to be consistent with the upper bound of a Fixed-Order
Next-to-Leading Logarithm calculation.Comment: 15 pages, 16 figures. Revised version submitted to Phys. Rev.
System size and energy dependence of near-side di-hadron correlations
Two-particle azimuthal () and pseudorapidity ()
correlations using a trigger particle with large transverse momentum () in
+Au, Cu+Cu and Au+Au collisions at =\xspace 62.4 GeV and
200~GeV from the STAR experiment at RHIC are presented. The \ns correlation is
separated into a jet-like component, narrow in both and
, and the ridge, narrow in but broad in .
Both components are studied as a function of collision centrality, and the
jet-like correlation is studied as a function of the trigger and associated
. The behavior of the jet-like component is remarkably consistent for
different collision systems, suggesting it is produced by fragmentation. The
width of the jet-like correlation is found to increase with the system size.
The ridge, previously observed in Au+Au collisions at = 200
GeV, is also found in Cu+Cu collisions and in collisions at
=\xspace 62.4 GeV, but is found to be substantially smaller at
=\xspace 62.4 GeV than at = 200 GeV for the
same average number of participants ().
Measurements of the ridge are compared to models.Comment: 17 pages, 14 figures, submitted to Phys. Rev.
Inclusive charged hadron elliptic flow in Au + Au collisions at = 7.7 - 39 GeV
A systematic study is presented for centrality, transverse momentum ()
and pseudorapidity () dependence of the inclusive charged hadron elliptic
flow () at midrapidity() in Au+Au collisions at
= 7.7, 11.5, 19.6, 27 and 39 GeV. The results obtained with
different methods, including correlations with the event plane reconstructed in
a region separated by a large pseudorapidity gap and 4-particle cumulants
(), are presented in order to investigate non-flow correlations and
fluctuations. We observe that the difference between and
is smaller at the lower collision energies. Values of , scaled by
the initial coordinate space eccentricity, , as a function
of are larger in more central collisions, suggesting stronger collective
flow develops in more central collisions, similar to the results at higher
collision energies. These results are compared to measurements at higher
energies at the Relativistic Heavy Ion Collider ( = 62.4 and 200
GeV) and at the Large Hadron Collider (Pb + Pb collisions at =
2.76 TeV). The values for fixed rise with increasing collision
energy within the range studied (). A comparison to
viscous hydrodynamic simulations is made to potentially help understand the
energy dependence of . We also compare the results to UrQMD
and AMPT transport model calculations, and physics implications on the
dominance of partonic versus hadronic phases in the system created at Beam
Energy Scan (BES) energies are discussed.Comment: 20 pages, 12 figures. Version accepted by PR
Isolation of Flow and Nonflow Correlations by Two- and Four-Particle Cumulant Measurements of Azimuthal Harmonics in 200 GeV Au+Au Collisions
A data-driven method was applied to measurements of Au+Au collisions at
200 GeV made with the STAR detector at RHIC to isolate
pseudorapidity distance -dependent and -independent
correlations by using two- and four-particle azimuthal cumulant measurements.
We identified a component of the correlation that is -independent,
which is likely dominated by anisotropic flow and flow fluctuations. It was
also found to be independent of within the measured range of
pseudorapidity . The relative flow fluctuation was found to be for particles of transverse momentum
less than GeV/. The -dependent part may be attributed to
nonflow correlations, and is found to be relative to the
flow of the measured second harmonic cumulant at
Charged-to-neutral correlation at forward rapidity in Au+Au collisions at =200 GeV
Event-by-event fluctuations of the ratio of inclusive charged to photon
multiplicities at forward rapidity in Au+Au collision at =200
GeV have been studied. Dominant contribution to such fluctuations is expected
to come from correlated production of charged and neutral pions. We search for
evidences of dynamical fluctuations of different physical origins. Observables
constructed out of moments of multiplicities are used as measures of
fluctuations. Mixed events and model calculations are used as baselines.
Results are compared to the dynamical net-charge fluctuations measured in the
same acceptance. A non-zero statistically significant signal of dynamical
fluctuations is observed in excess to the model prediction when charged
particles and photons are measured in the same acceptance. We find that, unlike
dynamical net-charge fluctuation, charge-neutral fluctuation is not dominated
by correlation due to particle decay. Results are compared to the expectations
based on the generic production mechanism of pions due to isospin symmetry, for
which no significant (<1%) deviation is observed.Comment: 14 pages, 6 figure
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