168 research outputs found
Effects of Zilpaterol Hydrochloride Supplementation on Growth Performance,Carcass Characteristics and Production Economics of SteersDiffering in Breed Composition
The β–adrenergic agonist zilpaterol hydrochloride (ZH) affects skeletal muscle growth, but little is known if this response is influenced by differences in genetic background of cattle. The objective of this study was to determine the effects of ZH on growth, carcass characteristics and production economic responses of Angus-sired (ANG) and SimAngus-sired (SIMANG) steers. Pens within each block × breed composition were randomly assigned to either ZH (8.3 ppm of DM; fed for the final 20 d before slaughter) or control (CON; 0 ppm ZH). Steers were ultrasounded before ZH inclusion and following withdrawal to determine the influence of ZH on change in ribeye area (REA), fat thickness and percent intramuscular fat (IMF). Carcass and feedlot performance data were collected and used to determine breed composition and ZH effects on economic responses. The interaction of breed composition × ZH had no influence on measured responses. Breed composition did not influence change in ultrasound measurements during the ZH feeding period or feedlot performance. Carcasses from SIMANG steers had larger REA and improved YG, while ANG steers had increased marbling scores. SimAngus-sired steers produced a greater percentage of YG 2 and a lower percentage of YG 3 carcasses than ANG steers. A greater proportion of ANG carcasses were classified as upper 2/3 Choice while a greater proportion of SIMANG carcasses were included in the lower 1/3 Choice designation. Carcass value per cwt was greater for ANG compared to SIMANG carcasses while other economic responses were similar. Feeding ZH improved ADG, YG, and REA and resulted in increased YG 2 carcasses. Total carcass value was greater for ZH compared to CON. While CON had increased IMF during ZH feeding, this did not manifest into differences in QG. Breed composition influenced carcass grid premiums, but not overall carcass value. Feeding ZH improved carcass value by increasing HCW. Responses among breed composition were as expected for ANG vs SIMANG cattle types. The resultant economic effect was that grid premiums for higher-grading ANG cattle were offset by larger HCW for SIMANG, leading to similar overall carcass values. Finally, the influence of ZH on growth and carcass traits was as expected with increased carcass value being realized through heavier HCW
Which forms of child/adolescent externalizing behaviors account for late adolescent risky sexual behavior and substance use?
Background: Health risk behaviors like substance use (alcohol, tobacco, soft/hard drugs) and risky sexual behavior become more prevalent in adolescence. Children with behavior problems are thought to be prone to engage in health risk behaviors later in life. It is, however, unclear which problems within the externalizing spectrum account for these outcomes. Methods: Three hundred and nine children were followed from age 4/5 years to 18 years (14-year follow-up). Level and course of parent-rated opposition, physical aggression, status violations and property violations were used to predict adolescent-reported substance use and risky sexual behavior at age 18 years. Results: Both level and change in physical aggression were unique predictors of all forms of adolescent health risk behavior. Levels of status violations predicted smoking and soft drug use only, while change in property violations predicted each of the health risk behaviors. The links between opposition and health risk behaviors were accounted for by co-occurring problem behaviors. Conclusions: Of externalizing problems, physical aggression is the best predictor of adolescent substance use and risky sexual behavior from childhood onwards. Possible explanations and implications of these findings, and future research directions are discussed. © 2007 The Authors
Dynamics of Warped Flux Compactifications
We discuss the four dimensional effective action for type IIB flux
compactifications, and obtain the quadratic terms taking warp effects into
account. The analysis includes both the 4-d zero modes and their KK
excitations, which become light at large warping. We identify an `axial' type
gauge for the supergravity fluctuations, which makes the four dimensional
degrees of freedom manifest. The other key ingredient is the existence of
constraints coming from the ten dimensional equations of motion. Applying these
conditions leads to considerable simplifications, enabling us to obtain the low
energy lagrangian explicitly. In particular, the warped K\"ahler potential for
metric moduli is computed and it is shown that there are no mixings with the KK
fluctuations and the result differs from previous proposals. The four
dimensional potential contains a generalization of the Gukov-Vafa-Witten term,
plus usual mass terms for KK modes.Comment: 37 pages. v2. References added, typos corrected. v3. Matches JHEP
versio
Single Spin Asymmetry in Polarized Proton-Proton Elastic Scattering at GeV
We report a high precision measurement of the transverse single spin
asymmetry at the center of mass energy GeV in elastic
proton-proton scattering by the STAR experiment at RHIC. The was measured
in the four-momentum transfer squared range \GeVcSq, the region of a significant interference between the
electromagnetic and hadronic scattering amplitudes. The measured values of
and its -dependence are consistent with a vanishing hadronic spin-flip
amplitude, thus providing strong constraints on the ratio of the single
spin-flip to the non-flip amplitudes. Since the hadronic amplitude is dominated
by the Pomeron amplitude at this , we conclude that this measurement
addresses the question about the presence of a hadronic spin flip due to the
Pomeron exchange in polarized proton-proton elastic scattering.Comment: 12 pages, 6 figure
High non-photonic electron production in + collisions at = 200 GeV
We present the measurement of non-photonic electron production at high
transverse momentum ( 2.5 GeV/) in + collisions at
= 200 GeV using data recorded during 2005 and 2008 by the STAR
experiment at the Relativistic Heavy Ion Collider (RHIC). The measured
cross-sections from the two runs are consistent with each other despite a large
difference in photonic background levels due to different detector
configurations. We compare the measured non-photonic electron cross-sections
with previously published RHIC data and pQCD calculations. Using the relative
contributions of B and D mesons to non-photonic electrons, we determine the
integrated cross sections of electrons () at 3 GeV/10 GeV/ from bottom and charm meson decays to be = 4.0({\rm
stat.})({\rm syst.}) nb and =
6.2({\rm stat.})({\rm syst.}) nb, respectively.Comment: 17 pages, 17 figure
Evolution of the differential transverse momentum correlation function with centrality in Au+Au collisions at GeV
We present first measurements of the evolution of the differential transverse
momentum correlation function, {\it C}, with collision centrality in Au+Au
interactions at GeV. {\it C} exhibits a strong dependence
on collision centrality that is qualitatively similar to that of number
correlations previously reported. We use the observed longitudinal broadening
of the near-side peak of {\it C} with increasing centrality to estimate the
ratio of the shear viscosity to entropy density, , of the matter formed
in central Au+Au interactions. We obtain an upper limit estimate of
that suggests that the produced medium has a small viscosity per unit entropy.Comment: 7 pages, 4 figures, STAR paper published in Phys. Lett.
Longitudinal double-spin asymmetry and cross section for inclusive neutral pion production at midrapidity in polarized proton collisions at sqrt(s) = 200 GeV
We report a measurement of the longitudinal double-spin asymmetry A_LL and
the differential cross section for inclusive Pi0 production at midrapidity in
polarized proton collisions at sqrt(s) = 200 GeV. The cross section was
measured over a transverse momentum range of 1 < p_T < 17 GeV/c and found to be
in good agreement with a next-to-leading order perturbative QCD calculation.
The longitudinal double-spin asymmetry was measured in the range of 3.7 < p_T <
11 GeV/c and excludes a maximal positive gluon polarization in the proton. The
mean transverse momentum fraction of Pi0's in their parent jets was found to be
around 0.7 for electromagnetically triggered events.Comment: 6 pages, 3 figures, submitted to Phys. Rev. D (RC
Longitudinal scaling property of the charge balance function in Au + Au collisions at 200 GeV
We present measurements of the charge balance function, from the charged
particles, for diverse pseudorapidity and transverse momentum ranges in Au + Au
collisions at 200 GeV using the STAR detector at RHIC. We observe that the
balance function is boost-invariant within the pseudorapidity coverage [-1.3,
1.3]. The balance function properly scaled by the width of the observed
pseudorapidity window does not depend on the position or size of the
pseudorapidity window. This scaling property also holds for particles in
different transverse momentum ranges. In addition, we find that the width of
the balance function decreases monotonically with increasing transverse
momentum for all centrality classes.Comment: 6 pages, 3 figure
Measurement of the Bottom contribution to non-photonic electron production in collisions at =200 GeV
The contribution of meson decays to non-photonic electrons, which are
mainly produced by the semi-leptonic decays of heavy flavor mesons, in
collisions at 200 GeV has been measured using azimuthal
correlations between non-photonic electrons and hadrons. The extracted
decay contribution is approximately 50% at a transverse momentum of GeV/. These measurements constrain the nuclear modification factor for
electrons from and meson decays. The result indicates that meson
production in heavy ion collisions is also suppressed at high .Comment: 6 pages, 4 figures, accepted by PR
Palaeoenvironmental control on distribution of crinoids in the Bathonian (Middle Jurassic) of England and France
Bulk sampling of a number of different marine and marginal marine lithofacies in the British Bathonian has allowed us to assess the palaeoenvironmental distribution of crinoids for the first time. Although remains are largely fragmentary, many species have been identified by comparison with articulated specimens from elsewhere, whilst the large and unbiased sample sizes allowed assessment of relative proportions of different taxa. Results indicate that distribution of crinoids well corresponds to particular facies. Ossicles of Chariocrinus and Balanocrinus dominate in deeper-water and lower-energy facies,with the former extending further into shallower-water facies than the latter. Isocrinus dominates in shallower water carbonate facies, accompanied by rarer comatulids, and was also present in the more marine parts of lagoons. Pentacrinites remains are abundant in very high-energy oolite shoal lithofacies. The presence of millericrinids within one, partly allochthonous lithofacies suggests the presence of an otherwise unknown hard substrate from which they have been transported. These results are compared to crinoid assemblages from other Mesozoic localities, and it is evident that the same morphological ad-aptations are present within crinoids from similar lithofacies throughout the Jurassic and Early Cretaceous
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