11,425 research outputs found

    Harmonization of welfare standards for the protection of pigs with the EU-rules: the case of Croatia

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    Three quarters of Croatian pigs are produced in small production units (1-5 sows) and on family farms with mixed farming activities. Only few farms have specialized production units with up-to-date technologies and comply with EU standards. The future competitiveness of Croatian pig production is therefore questionable unless production systems are changing. Modernisation will most probably result in the expansion and intensification of larger farms and the termination of a great number of small farms. The aim of this study was to investigate how the welfare of pigs on Croatian farms would be affected by modernisation. Seventeen Croatian pig farmers were interviewed to describe the different pig production systems, while the welfare of pigs was assessed using resource-based and animal-based welfare indicators. Three production systems were distinguished: part-time family farms (PFF), full-time family farms (FFF) and farm enterprises (FE). Resources-based welfare indicators were investigated in 17 pens located on seven PFF, 25 pens distributed across six FFF and seven pens were visited at two FE. Animal-based welfare indicators were assessed on 21 pigs at PFF, 90 pigs at FFF and 18 pigs at FE. The study demonstrated that different production systems have different welfare problems. Based on resource-based indicators pig welfare was better ensured on FE, but based on animal-based indicators there was no clear difference in welfare between the three production systems. Based on these findings is it unlikely that the modernisation of current production systems in Croatia will significantly improve pig welfare. From a welfare point of view, neither the enlargement nor the termination of pig farms can be supported. However, the number of farms involved in this study was too small to allow for generalisation. The case-study does, however, point at the importance of further studies into the specific welfare problems of each of the production-systems and their different solutions. These studies should be of larger scale in order to get a representative picture of pig welfare in Croatia, and its assurance within the process of modernisation

    The Phase Diagram and Spectrum of Gauge-Fixed Abelian Lattice Gauge Theory

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    We consider a lattice discretization of a covariantly gauge-fixed abelian gauge theory. The gauge fixing is part of the action defining the theory, and we study the phase diagram in detail. As there is no BRST symmetry on the lattice, counterterms are needed, and we construct those explicitly. We show that the proper adjustment of these counterterms drives the theory to a new type of phase transition, at which we recover a continuum theory of (free) photons. We present both numerical and (one-loop) perturbative results, and show that they are in good agreement near this phase transition. Since perturbation theory plays an important role, it is important to choose a discretization of the gauge-fixing action such that lattice perturbation theory is valid. Indeed, we find numerical evidence that lattice actions not satisfying this requirement do not lead to the desired continuum limit. While we do not consider fermions here, we argue that our results, in combination with previous work, provide very strong evidence that this new phase transition can be used to define abelian lattice chiral gauge theories.Comment: 42 pages, 30 figure

    Strongly coupled U(1) lattice gauge theory as a microscopic model of Yukawa theory

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    Dynamical chiral symmetry breaking in a strongly coupled U(1) lattice gauge model with charged fermions and scalar is investigated by numerical simulation. Several composite neutral states are observed, in particular a massive fermion. In the vicinity of the tricritical point of this model we study the effective Yukawa coupling between this fermion and the Goldstone boson. The perturbative triviality bound of Yukawa models is nearly saturated. The theory is quite similar to strongly coupled Yukawa models for sufficiently large coupling except the occurrence of an additional state -- a gauge ball of mass about half the mass of the fermion.Comment: 4 page

    Chiral Fermions on the Lattice through Gauge Fixing -- Perturbation Theory

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    We study the gauge-fixing approach to the construction of lattice chiral gauge theories in one-loop weak-coupling perturbation theory. We show how infrared properties of the gauge degrees of freedom determine the nature of the continuous phase transition at which we take the continuum limit. The fermion self-energy and the vacuum polarization are calculated, and confirm that, in the abelian case, this approach can be used to put chiral gauge theories on the lattice in four dimensions. We comment on the generalization to the nonabelian case.Comment: 31 pages, 5 figures, two refs. adde

    Optical Conductivity in a Two-Band Superconductor: Pb

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    We demonstrate the effect of bandstructure on the superconducting properties of Pb by calculating the strong-coupling features in the optical conductivity, σ(ω)\sigma(\omega), due to the electron-phonon interaction. The importance of momentum dependence in the calculation of the properties of superconductors has previously been raised for MgB2_2. Pb resembles MgB2_2 in that it is a two band superconductor in which the bands' contributions to the Fermi surface have very different topologies. We calculate σ(ω)\sigma(\omega) by calculating a memory function which has been recently used to analyze σ(ω)\sigma(\omega) of Bi2_2Sr2_2CaCu2_2O8+δ_{8+\delta}. In our calculations the two components of the Fermi surface are described by parameterizations of de Haas--van Alphen data. We use a phonon spectrum which is a fit to neutron scattering data. By including the momentum dependence of the Fermi surface good agreement is found with the experimentally determined strong-coupling features which can be described by a broad peak at around 4.5 meV and a narrower higher peak around 8 meV of equal height. The calculated features are found to be dominated by scattering between states within the third band. By contrast scattering between states in the second band leads to strong-coupling features in which the height of the high energy peak is reduced by 50\sim 50% compared to that of the low energy peak. This result is similar to that in the conventional isotropic (momentum independent) treatment of superconductivity. Our results show that it is important to use realistic models of the bandstructure and phonons, and to avoid using momentum averaged quantities, in calculations in order to get quantitatively accurate results

    Analysis of the Fusion Hindrance in Mass-symmetric Heavy Ion Reactions

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    The fusion hindrance, which is also denominated by the term extra-push, is studied on mass-symmetric systems by the use of the liquid drop model with the two-center parameterization. Following the idea that the fusion hindrance exists only if the liquid drop barrier (saddle point) is located at the inner side of the contact point after overcoming the outer Coulomb barrier, the reactions in which two barriers are overlapped with each other are determined. It is shown that there are many systems where the fusion hindrance does not exist for the atomic number of projectile or target nucleus Z43Z\leq43, while for Z>43Z>43, all of the mass-symmetric reactions are fusion-hindered.Comment: 6 pages, 4 figures. to be published in Sci. in China

    Adiabatic and Non-Adiabatic Contributions to the Free Energy from the Electron-Phonon Interaction for Na, K, Al, and Pb

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    We calculate the adiabatic contributions to the free energy due to the electron--phonon interaction at intermediate temperatures, 0kBT<ϵF0 \leqslant k_{B} T < \epsilon_{F} for the elemental metals Na, K, Al, and Pb. Using our previously published results for the nonadiabatic contributions we show that the adiabatic contribution, which is proportional to T2T^{2} at low temperatures and goes as T3T^{3} at high temperatures, dominates the nonadiabatic contribution for temperatures above a cross--over temperature, TcT_{c}, which is between 0.5 and 0.8 TmT_{m}, where TmT_{m} is the melting temperature of the metal. The nonadiabatic contribution falls as T1T^{-1} for temperatures roughly above the average phonon frequency.Comment: Updated versio

    Connie Myers v. Albertsons, Inc. : Brief of Appellee

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    Appeal of the Judgment of Michael Glasmann Based upon a Jury Verdict Second Judicial District Court Weber County, State of Uta

    Antenna-coupled TES bolometer arrays for CMB polarimetry

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    We describe the design and performance of polarization selective antenna-coupled TES arrays that will be used in several upcoming Cosmic Microwave Background (CMB) experiments: SPIDER, BICEP-2/SPUD. The fully lithographic polarimeter arrays utilize planar phased-antennas for collimation (F/4 beam) and microstrip filters for band definition (25% bandwidth). These devices demonstrate high optical efficiency, excellent beam shapes, and well-defined spectral bands. The dual-polarization antennas provide well-matched beams and low cross polarization response, both important for high-fidelity polarization measurements. These devices have so far been developed for the 100 GHz and 150 GHz bands, two premier millimeter-wave atmospheric windows for CMB observations. In the near future, the flexible microstrip-coupled architecture can provide photon noise-limited detection for the entire frequency range of the CMBPOL mission. This paper is a summary of the progress we have made since the 2006 SPIE meeting in Orlando, FL

    Antenna-coupled TES bolometer arrays for CMB polarimetry

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    We describe the design and performance of polarization selective antenna-coupled TES arrays that will be used in several upcoming Cosmic Microwave Background (CMB) experiments: SPIDER, BICEP-2/SPUD. The fully lithographic polarimeter arrays utilize planar phased-antennas for collimation (F/4 beam) and microstrip filters for band definition (25% bandwidth). These devices demonstrate high optical efficiency, excellent beam shapes, and well-defined spectral bands. The dual-polarization antennas provide well-matched beams and low cross polarization response, both important for high-fidelity polarization measurements. These devices have so far been developed for the 100 GHz and 150 GHz bands, two premier millimeter-wave atmospheric windows for CMB observations. In the near future, the flexible microstrip-coupled architecture can provide photon noise-limited detection for the entire frequency range of the CMBPOL mission. This paper is a summary of the progress we have made since the 2006 SPIE meeting in Orlando, FL
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