304 research outputs found

    Potential dietary feed additives with antibacterial effects and their impact on performance of weaned piglets : a meta-analysis

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    This meta-analysis evaluated the use of potential dietary feed additives (pDFA) with antibacterial effects and their impact on the perfomance of weaned piglets. Twenty-three peer-reviewed in vivo studies, comprising 50 trials, were identified between January 2010 and January 2017. The pDFA in these studies could be grouped in 5 classes: antimicrobial peptides, chitosan, lysozyme, medium chain fatty acids/triglycerides and plant extracts. Mixed-effect meta-analyses with type of pDFA as fixed effect were performed for the growth parameters 'average daily gain' (ADG) and 'feed conversion ratio' (FCR), which are the two most important and used economic performance parameters for farmers. For each class of pDFA, results of the meta-analysis showed significantly higher average daily gain in the group with pDFA compared to the negative control group, while no significant difference with the positive control group was observed. Furthermore, a positive effect on FCR was found, i.e. significantly less feed was needed to gain 1 kg of body weight in the group with pDFA compared to the negative control group. No significant differences with positive control groups were observed for each class of pDFA, except for plant extracts, where the FCR was also significantly reduced in the treatment group. These results suggest that pDFA could reduce the use of antimicrobials without significant negative effects on performance indicators

    Potential dietary feed additives with antibacterial effects and their impact on performance of weaned piglets: A meta-analysis

    Get PDF
    This meta-analysis evaluated the use of potential dietary feed additives (pDFA) with antibacterial effects and their impact on the perfomance of weaned piglets. Twenty-three peer-reviewed in vivo studies, comprising 50 trials, were identified between January 2010 and January 2017. The pDFA in these studies could be grouped in 5 classes: antimicrobial peptides, chitosan, lysozyme, medium chain fatty acids/ triglycerides and plant extracts. Mixed-effect meta-analyses with type of pDFA as fixed effect were performed for the growth parameters ‘average daily gain’ (ADG) and ‘feed conversion ratio’ (FCR), which are the two most important and used economic performance parameters for farmers. For each class of pDFA, results of the meta-analysis showed significantly higher average daily gain in the group with pDFA compared to the negative control group, while no significant difference with the positive control group was observed. Furthermore, a positive effect on FCR was found, i.e. significantly less feed was needed to gain 1 kg of body weight in the group with pDFA compared to the negative control group. No significant differences with positive control groups were observed for each class of pDFA, except for plant extracts, where the FCR was also significantly reduced in the treatment group. These results suggest that pDFA could reduce the use of antimicrobials without significant negative effects on performance indicators

    Evolution of antimicrobial resistance of Salmonella isolates from pigs in Belgium

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    The aim of the present study was to investigate the antimicrobial sensitivity of Salmonella isolates from pigs between 2011 and 2015. In total, 275 Salmonella isolates from samples originating from pigs sent in for diagnostic examination at Animal Health Care Flanders were tested for their sensitivity against different antimicrobials. Except for colistin, where the disk prediffusion test was used, the disk diffusion test was used. E. coli ATCC 25922 was used as reference isolate and the interpretative breakpoints were based on the Clinical and Laboratory Standards Institute

    Saturation of nuclear matter and short-range correlations

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    A fully self-consistent treatment of short-range correlations in nuclear matter is presented. Different implementations of the determination of the nucleon spectral functions for different interactions are shown to be consistent with each other. The resulting saturation densities are closer to the empirical result when compared with (continuous-choice) Brueckner-Hartree-Fock values. Arguments for the dominance of short-range correlations in determining the nuclear-matter saturation density are presented. A further survey of the role of long-range correlations suggests that the inclusion of pionic contributions to ring diagrams in nuclear matter leads to higher saturation densities than empirically observed. A possible resolution of the nuclear-matter saturation problem is suggested.Comment: 5 pages, 1 figure, to be published in Phys.Rev.Let

    Self-consistent Approach to Off-Shell Transport

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    The properties of two forms of the gradient expanded Kadanoff--Baym equations, i.e. the Kadanoff--Baym and Botermans-Malfliet forms, suitable to describe the transport dynamics of particles and resonances with broad spectral widths, are discussed in context of conservation laws, the definition of a kinetic entropy and the possibility of numerical realization. Recent results on exact conservations of charge and energy-momentum within Kadanoff-Baym form of quantum kinetics based on local coupling schemes are extended to two cases relevant in many applications. These concern the interaction via a finite range potential, and, relevant in nuclear and hadron physics, e.g. for the pion--nucleon interaction, the case of derivative coupling.Comment: 35 pages, submitted to issue of Phys. Atom. Nucl. dedicated to S.T. Belyaev on the occasion of his 80th birthday. Few references are adde

    Chemically modified dsRNA induces RNAi effects in insects in vitro and in vivo: a potential new tool for improving RNA-based plant protection

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    Global agriculture loses over $100 billion of produce annually to crop pests such as insects. Many of these crop pests either are not currently controlled by artificial means or have developed resistance against chemical pesticides. Long dsRNAs are capable of inducing RNAi in insects and are emerging as novel, highly selective alternatives for sustainable insect management strategies. However, there are significant challenges associated with RNAi efficacy in insects. In this study, we synthesized a range of chemically modified long dsRNAs in an approach to improve nuclease resistance and RNAi efficacy in insects. Our results showed that dsRNAs containing phosphorothioate modifications demonstrated increased resistance to southern green stink bug saliva nucleases. Phosphorothioate-modified and 2′-fluoro-modified dsRNA also demonstrated increased resistance to degradation by soil nucleases and increased RNAi efficacy in Drosophila melanogaster cell cultures. In live insects, we found chemically modified long dsRNAs successfully resulted in mortality in both stink bug and corn rootworm. These results provide further mechanistic insight into the dependence of RNAi efficacy on nucleotide modifications in the sense or antisense strand of the dsRNA in insects and demonstrate for the first time that RNAi can successfully be triggered by chemically modified long dsRNAs in insect cells or live insects

    Search for Point Sources of High Energy Neutrinos with AMANDA

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    This paper describes the search for astronomical sources of high-energy neutrinos using the AMANDA-B10 detector, an array of 302 photomultiplier tubes, used for the detection of Cherenkov light from upward traveling neutrino-induced muons, buried deep in ice at the South Pole. The absolute pointing accuracy and angular resolution were studied by using coincident events between the AMANDA detector and two independent telescopes on the surface, the GASP air Cherenkov telescope and the SPASE extensive air shower array. Using data collected from April to October of 1997 (130.1 days of livetime), a general survey of the northern hemisphere revealed no statistically significant excess of events from any direction. The sensitivity for a flux of muon neutrinos is based on the effective detection area for through-going muons. Averaged over the Northern sky, the effective detection area exceeds 10,000 m^2 for E_{mu} ~ 10 TeV. Neutrinos generated in the atmosphere by cosmic ray interactions were used to verify the predicted performance of the detector. For a source with a differential energy spectrum proportional to E_{nu}^{-2} and declination larger than +40 degrees, we obtain E^2(dN_{nu}/dE) <= 10^{-6}GeVcm^{-2}s^{-1} for an energy threshold of 10 GeV.Comment: 46 pages, 22 figures, 4 tables, submitted to Ap.

    Self-consistent Green's function approaches

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    We present the fundamental techniques and working equations of many-body Green's function theory for calculating ground state properties and the spectral strength. Green's function methods closely relate to other polynomial scaling approaches discussed in chapters 8 and 10. However, here we aim directly at a global view of the many-fermion structure. We derive the working equations for calculating many-body propagators, using both the Algebraic Diagrammatic Construction technique and the self-consistent formalism at finite temperature. Their implementation is discussed, as well as the inclusion of three-nucleon interactions. The self-consistency feature is essential to guarantee thermodynamic consistency. The pairing and neutron matter models introduced in previous chapters are solved and compared with the other methods in this book.Comment: 58 pages, 14 figures, Submitted to Lect. Notes Phys., "An advanced course in computational nuclear physics: Bridging the scales from quarks to neutron stars", M. Hjorth-Jensen, M. P. Lombardo, U. van Kolck, Editor

    In medium T-matrix for superfluid nuclear matter

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    We study a generalized ladder resummation in the superfluid phase of the nuclear matter. The approach is based on a conserving generalization of the usual T-matrix approximation including also anomalous self-energies and propagators. The approximation here discussed is a generalization of the usual mean-field BCS approach and of the in medium T-matrix approximation in the normal phase. The numerical results in this work are obtained in the quasi-particle approximation. Properties of the resulting self-energy, superfluid gap and spectral functions are studied.Comment: 38 pages, 19 figures, Introduction rewritten, Refs. adde
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