614 research outputs found

    Dramatic reductions of in feed medication via immunization against enteric pathogens

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    The use of in-feed antimicrobials is coming under increased pressure in food animal production. Five field studies examined the impact of vaccines to stimulate protective immunity against pathogens commonly controlled with in-feed antimicrobials (Lawsonia intracellularis, a common enteric pathogen causing ileitis). Grow-finish pigs were immunized and various levels of in-feed antimicrobials used to control or prevent Lawsonia were removed

    A hard metallic material: Osmium Diboride

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    We calculate the structural and electronic properties of OsB2 using density functional theory with or without taking into account spin-orbit (SO) interaction. Our results show that the bulk modulus with and without SO interaction are 364 and 365 Gpa respectively, both are in good agreement with experiment (365-395 Gpa). The evidence of covalent bonding of Os-B, which plays an important role to form a hard material, is indicated both in charge density, atoms in molecules analysis, and density of states analysis. The good metallicity and hardness of OsB2 might suggest its potential application as hard conductors.Comment: Figures improve

    Optical-Depth Scaling of Light Scattering From a Dense and Cold Atomic \u3csup\u3e87\u3c/sup\u3eRb Gas

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    We report investigation of near-resonance light scattering from a cold and dense atomic gas of 87Rb atoms. Measurements are made for probe frequencies tuned near the F=2→ F\u27=3 nearly closed hyperfine transition, with particular attention paid to the dependence of the scattered light intensity on detuning from resonance, the number of atoms in the sample, and atomic sample size. We find that, over a wide range of experimental variables, the optical depth of the atomic sample serves as an effective single scaling parameter which describes well all the experimental data

    Nucleotide sequence of the structural gene (pyrB) that encodes the catalytic polypeptide of aspartate transcarbamoylase of Escherichia coli.

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    The deoxyribonucleotide sequence of pyrB, the cistron encoding the catalytic subunit of aspartate transcarbamoylase (carbamoylphosphate: L-aspartate carbamoyltransferase, EC 2.1.3.2), has been determined. The pyrB gene encodes a polypeptide of 311 amino acid residues initiated by an NH2-terminal methionine that is not present in the catalytically active polypeptide. The DNA sequence analysis revealed the presence of an eight-amino-acid sequence beginning at Met-219 that was not detected in previous analyses of amino acid sequence. This octapeptide sequence provides an additional component of the disordered loop in the equatorial domain of the catalytic polypeptide. It had been found previously that the catalytic polypeptide is expressed from a bicistronic operon that also produces the regulatory polypeptide encoded by pyrI. A single transcriptional control region precedes the structural gene of the catalytic polypeptide and a simple 15-base-pair region separates its COOH terminus from the structural gene of the regulatory polypeptide. The chain-terminating codon of the catalytic polypeptide may contribute to the ribosomal binding site for the regulatory polypeptide and thus assist coordinate expression of the two cistrons

    Use of SC54 for the reduction of salmonella in swine

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    Infections caused by S. choleraesuis have significant economic impact on pork production in the United States (Wilcock and Schwartz 1992). An avirulent live culture vaccine has been described for the purpose of protecting pigs against infections caused by S. choleraesuis (Kramer, Roof et al. 1992) (Roof and Doitchinoff 1995). Other serotypes of Salmonella have been associated with infections in swine in the United States. These includeS. typhimurium and S. typhisuis (Wilcock and Schwartz 1992), S. heidelberg (Reed, Olander et al. 1985), and S. agona (Fernandez, Duhamel et al. 1993). Two experiments were conducted. Experiment number I was designed to determine the effect of an avirulent live culture vaccine (SC540, NOBL Laboratories, Inc.) in swine on an experimental infection of S. typhimurium. Experiment number 2 was designed to determine the effect of SC540 on Salmonella serogroups within a commercial swine farm
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