1,207 research outputs found
Long-Term Protection from Bovine Viral Diarrhea Virus in Feedlot Cattle
Bovine viral diarrhea virus (BVDV) causes respiratory and reproductive disease. The duration of immunity of an inactivated vaccine (Virashield 5: Grand Laboratories, Freeman, SD) was measured in two challenge studies. In both studies the vaccinated animals demonstrated fewer clinical signs when challenged with Type II BVDV at 11 or 13 months post vaccination. These results indicate that an inactivated vaccine administered properly can protect animals against disease up to at least a year post vaccination
Next--to--Leading Order Corrections to Meson Masses in the Heavy Quark Effective Theory
We use the QCD sum rule approach to calculate the splitting between vector
and pseudoscalar mesons containing one light and one heavy quark, and the
kinetic energy of the heavy quark. Our result for the splitting induced by the
chromomagnetic interaction agrees to the experimental data on charm and beauty
mesons. For the matrix element of the kinetic energy operator, we obtain the
value .Comment: 33 ps., PS figures included, requires REVTEX.3 and psfig,
TUM-T31-42/93/R (additional contribution to kinetic energy taken into
account, marginal changes in the results
Bjorken unpolarized and polarized sum rules: comparative analysis of large-N_F expansions
Analytical all-orders results are presented for the one-renormalon-chain
contributions to the Bjorken unpolarized sum rule for the F_1 structure
function of nu N deep-inelastic scattering in the large-N_F limit. The
feasibility of estimating higher order perturbative QCD corrections, by the
process of naive nonabelianization (NNA), is studied, in anticipation of
measurement of this sum rule at a Neutrino Factory. A comparison is made with
similar estimates obtained for the Bjorken polarized sum rule. Application of
the NNA procedure to correlators of quark vector and scalar currents, in the
euclidean region, is compared with recent analytical results for the
O(alpha_s^4 N_F^2) terms.Comment: 9 page
On the Nature of the Phase Transition in SU(N), Sp(2) and E(7) Yang-Mills theory
We study the nature of the confinement phase transition in d=3+1 dimensions
in various non-abelian gauge theories with the approach put forward in [1]. We
compute an order-parameter potential associated with the Polyakov loop from the
knowledge of full 2-point correlation functions. For SU(N) with N=3,...,12 and
Sp(2) we find a first-order phase transition in agreement with general
expectations. Moreover our study suggests that the phase transition in E(7)
Yang-Mills theory also is of first order. We find that it is weaker than for
SU(N). We show that this can be understood in terms of the eigenvalue
distribution of the order parameter potential close to the phase transition.Comment: 15 page
Understanding and meeting information needs following unintentional injury: comparing the accounts of patients, carers and service providers
Objective. To explore information needs of unintentional injury patients and their carers over time, across services, and how such needs are met from the perspectives of patients, carers and service providers
Next-to-next-to-leading order prediction for the photon-to-pion transition form factor
We evaluate the next-to-next-to-leading order corrections to the
hard-scattering amplitude of the photon-to-pion transition form factor. Our
approach is based on the predictive power of the conformal operator product
expansion, which is valid for a vanishing -function in the so-called
conformal scheme. The Wilson--coefficients appearing in the non-forward
kinematics are then entirely determined from those of the polarized
deep-inelastic scattering known to next-to-next-to-leading accuracy. We propose
different schemes to include explicitly also the conformal symmetry breaking
term proportional to the -function, and discuss numerical predictions
calculated in different kinematical regions. It is demonstrated that the
photon-to-pion transition form factor can provide a fundamental testing ground
for our QCD understanding of exclusive reactions.Comment: 62 pages LaTeX, 2 figures, 9 tables; typos corrected, some references
added, to appear in Phys. Rev.
Expansion of bound state energies in powers of m/M and (1-m/M)
Elaborating on a previous letter, we use a new approach to compute energy
levels of a non-relativistic bound-state of two constituents, with masses m and
M, by systematic expansions - one in powers of m/M and another in powers of
(1-m/M). Technical aspects of the calculations are described in detail.
Theoretical predictions are given for O(alpha(Z*alpha)^5) radiative recoil and
O((Z*alpha)^6) pure recoil corrections to the average energy shift and
hyperfine splitting relevant for hydrogen, muonic hydrogen, and muonium.Comment: 9 pages, revte
Pairing correlations and transitions in nuclear systems
We discuss several pairing-related phenomena in nuclear systems, ranging from
superfluidity in neutron stars to the gradual breaking of pairs in finite
nuclei. We describe recent experimental evidence that points to a relation
between pairing and phase transitions (or transformations) in finite nuclear
systems. A simple pairing interaction model is used in order to study and
classify an eventual pairing phase transition in finite fermionic systems such
as nuclei. We show that systems with as few as 10-16 fermions can exhibit clear
features reminiscent of a phase transition.Comment: Proceedings of COMEX1, Sorbonne, Paris, june 10-13 2003. To appear in
Nuclear Physics
Nonlinear sliding friction of adsorbed overlayers on disordered substrates
We study the response of an adsorbed monolayer on a disordered substrate
under a driving force using Brownian molecular-dynamics simulation. We find
that the sharp longitudinal and transverse depinning transitions with
hysteresis still persist in the presence of weak disorder. However, the
transitions are smeared out in the strong disorder limit. The theoretical
results here provide a natural explanation for the recent data for the
depinning transition of Kr films on gold substrate.Comment: 8 pages, 8 figs, to appear in Phys. Rev.
Vortex Pinball Under Crossed AC Drives in Superconductors with Periodic Pinning Arrays
Vortices driven with both a transverse and a longitudinal AC drive which are
out of phase are shown to exhibit a novel commensuration-incommensuration
effect when interacting with periodic substrates. For different AC driving
parameters, the motion of the vortices forms commensurate orbits with the
periodicity of the pinning array. When the commensurate orbits are present,
there is a finite DC critical depinning threshold, while for the incommensurate
phases the vortices are delocalized and the DC depinning threshold is absent.Comment: 4 pages, 4 postscript figure
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