8,790 research outputs found

    The Thermodynamics of Cosmic String densities in U(1) Scalar Field Theory

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    We present a full characterization of the phase transition in U(1) scalar field theory and of the associated vortex string thermodynamics in 3D. We show that phase transitions in the string densities exist and measure their critical exponents, both for the long string and the short loops. Evidence for a natural separation between these two string populations is presented. In particular our results strongly indicate that an infinite string population will only exist above the critical temperature. Canonical initial conditions for cosmic string evolution are show to correspond to the infinite temperature limit of the theory.Comment: 4 pages, 4 figures, RevTe

    Predicting the critical density of topological defects in O(N) scalar field theories

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    O(N) symmetric λϕ4\lambda \phi^4 field theories describe many critical phenomena in the laboratory and in the early Universe. Given N and D≀3D\leq 3, the dimension of space, these models exhibit topological defect classical solutions that in some cases fully determine their critical behavior. For N=2, D=3 it has been observed that the defect density is seemingly a universal quantity at T_c. We prove this conjecture and show how to predict its value based on the universal critical exponents of the field theory. Analogously, for general N and D we predict the universal critical densities of domain walls and monopoles, for which no detailed thermodynamic study exists. This procedure can also be inverted, producing an algorithm for generating typical defect networks at criticality, in contrast to the canonical procedure, which applies only in the unphysical limit of infinite temperature.Comment: 4 pages, 3 figures, uses RevTex, typos in Eq.(11) and (14) correcte

    Towards zero solid waste: utilising tannery waste as a protein source for poultry feed

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    Zero waste is now a strongly emerging issue for sustainable industrial development where minimisation and utilisation of waste are a priority in the leather industry. In a tannery hides and skins converted in to leather through various processes. Approximately 20% (w/w) of the chrome containing tannery solid waste (TSW) is generated from one tonne of raw hides and skins. However, tannery solid waste may also be a resource if it is managed expertly as we move towards zero waste. This research illustrates the potential of tannery solid waste as a poultry feed additive. An oxidation method was used to achieve 95% of dechroming rate of chrome tanned waste followed with thermal and enzymatic treatment to produce gelatin solution and collagen concentrates. The thermal stability and fibre structure of samples were analysed by Differential Scanning Calorimeter (DSC) and Scanning Electron Microscope (SEM). Protein content and fourteen amino acid concentrations were determined using amino acid analysis. High Performance Liquid Chromatography (HPLC) was used to compare the amino acid composition with wheat and soya bean meal that is conventionally used in poultry feed. The nutrient requirements for poultry feed vary according to the purpose for which they have been developed. The high content of arginine, leucine, threonine, serine and methionine in the extract were of a sufficient level for poultry feed. Hexavalent chromium test was performed and showed that levels of the metal were low enough to be used in feed additives. In addition, the extracted product showed 75% digestibility (in vitro) and appears that treated TSW may be utilised in poultry feed, this demonstrates a clear example of waste utilisation. In Bangladesh plans are being formed to use the extract in poultry feed production

    Anisakis infection in allis shad, Alosa alosa (Linnaeus, 1758), and twaite shad, Alosa fallax (LacépÚde, 1803), from Western Iberian Peninsula Rivers : zoonotic and ecological implications

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    Acknowledgments The authors would like to thank M. N. Cueto and J.M. Antonio (ECOBIOMAR) for their excellent technical support and also Rodrigo López for making the map of the study area. We also thank the personal of the Vigo IEO, for providing information about shad captures at sea collected on the basis of national program (AMDES) included in the European Data Collection Framework (DCF) project. We are also grateful to Comandancia Naval de Tui for providing fishing data. M. Bao is supported by a PhD grant from the University of Aberdeen and also by financial support of the contract from the EU Project PARASITE (grant number 312068). This study was partially supported by a PhD grant from the Portuguese Foundation for Science and Technology (FCT) SFRH/BD/44892/2008) and partially supported by the European Regional Development Fund (ERDF) through the COMPETE—Operational Competitiveness Programme and national funds through Foundation for Science and Technology (FCT), under the project BPEst-C/MAR/ LA0015/2013. The authors thank the staff of the Station of Hydrobiology of the USC BEncoro do Con^ due their participation in the surveys. This work has been partially supported by the project 10PXIB2111059PR of the Xunta de Galicia and the project MIGRANET of the Interreg IV BSUDOE (South-West Europe) Territorial Cooperation Programme (SOE2/P2/E288). D.J. Nachón is supported by a PhD grant from the Xunta de Galicia (PRE/2011/198)Peer reviewedPostprin

    Methods of isolation and identification of pathogenic and potential pathogenic bacteria from skins and tannery effluents

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    Currently there is no standard protocol available within the leather industry to isolate and identify pathogenic bacteria from hides, skins or tannery effluent. This study was therefore carried out to identify simple but effective methods for isolation and identification of bacterial pathogens from the effluent and skins during leather processing. Identification methods based on both phenotypic and genotypic characteristics were investigated. Bacillus cereus and Pseudomonas aeruginosa were used as indicator bacteria to evaluate the isolation and identification methods. Decontaminated calfskins were inoculated with a pure culture of the above mentioned bacterial species followed by a pre-tanning and chromium tanning processes. Effluent samples were collected and skins were swabbed at the end of each processing stage. Bacterial identification was carried out based on the phenotypic characteristics; such as colony appearance on selective solid media, cell morphology following a standard Gram-staining and spore staining techniques, and biochemical reactions, e.g., the ability of a bacterial species to ferment particular sugars and ability to produce certain enzymes. Additionally, an identification system based on bacterial phenotypic characteristics, known as BiologÂź system was applied. A pulsed-filed gel electrophoresis (PFGE) method for bacterial DNA fingerprinting was also evaluated and used for the identification of the inoculated bacteria. The methods described in the study were found to be effective for the identification of pathogenic bacteria from skins and effluent

    Estimation of Precision and Uncertainty of a Calibration Artefact for CMMs

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    A new kind of artefact, based on a modification of the hexapod machine’s well-known structure, has been introduced by Antunes, S. D. et al in [1], in order to determine the global errors of coordinate measuring machines. Here we are presenting results from validation of the technique: using a self-calibrated method and modeling the reference value for calibration based on laser trilateration

    Structural health monitoring of different geometry structures with optical fiber sensors

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    In this paper, we describe the structural health monitoring of several structures, with different geometry, materials and behaviors, using optical fiber sensors. Those studies aimed to demonstrate the feasibility of such technologies in structural health monitoring, with all the advantages inherent to the optical fiber technology

    Numerical simulation of stochastic vortex tangles

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    We present the results of simulation of the chaotic dynamics of quantized vortices in the bulk of superfluid He II. Evolution of vortex lines is calculated on the base of the Biot-Savart law. The dissipative effects appeared from the interaction with the normal component, or/and from relaxation of the order parameter are taken into account. Chaotic dynamics appears in the system via a random forcing, e.i. we use the Langevin approach to the problem. In the present paper we require the correlator of the random force to satisfy the fluctuation-disspation relation, which implies that thermodynamic equilibrium should be reached. In the paper we describe the numerical methods for integration of stochastic differential equation (including a new algorithm for reconnection processes), and we present the results of calculation of some characteristics of a vortex tangle such as the total length, distribution of loops in the space of their length, and the energy spectrum.Comment: 8 pages, 5 figure
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