5,846 research outputs found

    Origin and assessment of bruises in beef cattle at slaughter

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    Studies of bruises, as detected on carcasses at the slaughterhouse, may provide useful information about the traumatic situations the animals endure during the pre-slaughter period. In this paper, we review scientific data on the prevalence, risk factors and estimation of the age of bruises in beef cattle. Risk factors such as animal characteristics, transport conditions, stocking density, livestock auction and handling of the animals are discussed. Investigation of the age of bruises could provide information on when in the meat chain bruises occur and, could help to pinpoint where preventive measures should be taken, from the stage of collecting the animals on the farm until slaughter. We review the methods available to assess the age of the bruises; data on human forensic research are also included. The feasibility to identify traumatic episodes during the pre-slaughter period, in order to improve animal welfare is discusse

    Dispersion relation formalism for virtual Compton scattering off the proton

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    We present in detail a dispersion relation formalism for virtual Compton scattering (VCS) off the proton from threshold into the Δ(1232)\Delta(1232)-resonance region. Such a formalism can be used as a tool to extract the generalized polarizabilities of the proton from both unpolarized and polarized VCS observables over a larger energy range. We present calculations for existing and forthcoming VCS experiments and demonstrate that the VCS observables in the energy region between pion production threshold and the Δ(1232)\Delta(1232)-resonance show an enhanced sensitivity to the generalized polarizabilities.Comment: 51 pages, 15 figure

    Dispersion analysis for generalized spin polarizabilities

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    We report on a dispersion relation formalism for the virtual Compton scattering (VCS) reaction on the proton, which for the first time allows a dispersive evaluation of 4 generalized polarizabilities. The dispersion formalism provides a new tool to analyze VCS experiments above pion threshold, thus increasing the sensitivity to the generalized polarizabilities of the nucleon.Comment: 5pages, 2 figures, to appear in the Proceedings of the Symposium on the Gerasimov-Drell-Hearn Sum Rule and the Spin Structure in the Nucleon Resonance Region (GDH2000), June 14-17 2000, Mainz, German

    Twist-2 Generalized TMDs and the Spin/Orbital Structure of the Nucleon

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    Generalized transverse-momentum dependent parton distributions (GTMDs) encode the most general parton structure of hadrons. Here we focus on two twist-2 GTMDs which are denoted by F1,4F_{1,4} and G1,1G_{1,1} in parts of the literature. As already shown previously, both GTMDs have a close relation to orbital angular momentum of partons inside a hadron. However, recently even the mere existence of F1,4F_{1,4} and G1,1G_{1,1} has been doubted. We explain why this claim does not hold. We support our model-independent considerations by calculating the two GTMDs in the scalar diquark model and in the quark-target model, where we also explicitly check the relation to orbital angular momentum. In addition, we compute F1,4F_{1,4} and G1,1G_{1,1} at large transverse momentum in perturbative Quantum Chromodynamics and show that they are nonzero.Comment: 29 pages, 6 figures; two clarifications and a reference added; version to appear in Phys. Rev.

    Optical spectroscopy and photodissociation dynamics of multiply charged ions

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    Multiply charged ions are intruiging species whose reactivity and thermodynamic stability depends on the extent of ligation. The possibility of dissociating to two singly charged ions, which is often highly exothermic, leads to spectroscopy and dissociation dynamics that are qualitatively different from their singly charged counterparts. Various methods of producing multiply charged ions are discussed. Spectroscopy of small molecular dications, ligated/solvated transition metal dications, and multiply charged biological ions and metal cluster ions are discussed, with emphasis on our studies of d–d transitions in solvated transition metal dications, and the ensuing dissociation dynamics

    Observing collapse in two colliding dipolar Bose-Einstein condensates

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    We study the collision of two Bose-Einstein condensates with pure dipolar interaction. A stationary pure dipolar condensate is known to be stable when the atom number is below a critical value. However, collapse can occur during the collision between two condensates due to local density fluctuations even if the total atom number is only a fraction of the critical value. Using full three-dimensional numerical simulations, we observe the collapse induced by local density fluctuations. For the purpose of future experiments, we present the time dependence of the density distribution, energy per particle and the maximal density of the condensate. We also discuss the collapse time as a function of the relative phase between the two condensates.Comment: 6 pages, 7 figure

    Vibrational Spectroscopy of Intermediates in Benzene-to-Pheno Conversion by FeO+

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    Gas-phase FeO+ can convert benzene to phenol under thermal conditions. Two key intermediates of this reaction are the [HO-Fe-C6H5]+ insertion intermediate and Fe+(C6H5OH) exit channel complex. These intermediates are selectively formed by reaction of laser ablated Fe+ with specific organic precursors and are cooled in a supersonic expansion. Vibrational spectra of the sextet and quartet states of the intermediates in the O–H stretching region are measured by infrared multiphoton dissociation (IRMPD). For Fe+(C6H5OH), the O–H stretch is observed at 3598 cm−1. Photodissociation primarily produces Fe+ + C6H5OH; Fe+(C6H4) + H2O is also observed. IRMPD of [HO-Fe-C6H5]+ mainly produces FeOH+ + C6H5 and the O–H stretch spectrum consists of a peak at ∌3700 cm−1 with a shoulder at ∌3670 cm−1. Analysis of the experimental results is aided by comparison with hybrid density functional theory computed frequencies. Also, an improved potential energy surface for the FeO+ + C6H6 reaction is developed based on CBS-QB3 calculations for the reactants, intermediates, transition states, and products

    Evolutionary branching in a stochastic population model with discrete mutational steps

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    Evolutionary branching is analysed in a stochastic, individual-based population model under mutation and selection. In such models, the common assumption is that individual reproduction and life career are characterised by values of a trait, and also by population sizes, and that mutations lead to small changes in trait value. Then, traditionally, the evolutionary dynamics is studied in the limit of vanishing mutational step sizes. In the present approach, small but non-negligible mutational steps are considered. By means of theoretical analysis in the limit of infinitely large populations, as well as computer simulations, we demonstrate how discrete mutational steps affect the patterns of evolutionary branching. We also argue that the average time to the first branching depends in a sensitive way on both mutational step size and population size.Comment: 12 pages, 8 figures. Revised versio

    CCS from industrial sources

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    The literature concerning the application of CCS to industry is reviewed. Costs are presented for different sectors including ``high purity'' (processes which inherently produce a high concentration of CO2), cement, iron and steel, refinery and biomass. The application of CCS to industry is a field which has had much less attention than its application to the electricity production sector. Costs range from less than 201110/tCO2uptoabove2011 10/tCO 2 up to above 2011 100/tCO 2 . In the words of a synthesis report from the United Nations Industrial Development Organisation (UNIDO) ``This area has so far not been the focus of discussions and therefore much attention needs to be paid to the application of CCS to industrial sources if the full potential of CCS is to be unlocked''
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