1,551 research outputs found

    Some aspects of the pathology and pathogenesis of bovine tuberculosis (and other published papers)

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    BOVINE TUBERCULOSIS: (1) Introduction (2) Pathogenesis of bovine tuberculosis as based on abattoir records (3) Distribution of the bronchial tree in the bovine lung (4) Bovine pulmonary tuberculosis - (a) Primary infection; (b) Phthisis (5) Tuberculosis of the bovine udder (6) All outbreak of bovine tuberculosis due to udder irrigation (7) References.ABORTION IN SHEEP: (1) Introduction (2) Enzootic abortion in ewes. Reprint (3) Developmental forms of the virus of ovine enzootic abortion. (4) Enzootic abortion in ewes and the complement fixation test. (5) Enzootic abortion in ewes. Immunisation and infection experiments. (6) Tick borne fever as a cause of abortion in sheep. (7) ReferencesMIISCELLANEOUS PUBLICATIONS: (1) Bovine tuberculosis - incorporating a review of John Francis' book. (2) A field trial of M42 (D.D.T.) dip in the control of sheep myiasis. (3) A disease survey of Sourhope Farm

    The Corporate-Consumer Power Dynamic Operating Behind the International Intellectual Property Regime: An Intractable Development Model with Uneven Results

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    The corporate-consumer power dynamic operating behind the international intellectual property regime has created a development model that perpetuates the hegemonic power of corporate elites and their governmental agents at the expense of developing nations. The inequity of the regime seems to be rooted in the paradoxical delegation of exclusive intellectual property rights to private corporate interests who dispense knowledge as a global public good. However, the inequality actually begins with the inception of knowledge itself and is the consequence of natural exclusivity over one’s own thoughts and creations, including how those ideas are conveyed to the public sphere. The freedom to pool individual ideas and resources into corporate structures, combined with the propagation of consumerism, has led to remarkable innovations, but it has also facilitated the concentration of corporate power and the projection of that power abroad. Propelled by this power dynamic, multinational corporations have successfully lobbied for the international restriction of knowledge as a global public good, thereby frustrating attempts to promote a more equitable development model. Nevertheless, an understanding of how the corporate-consumer dynamic operates can help advance potential solutions to address the inequities, while at the same time retaining the beneficial aspects of the regime. By fostering an enlightened global citizenship that is more consistent with public works projects, a new corporate ethic may begin to acknowledge sustainable development goals and embrace a more equitable distribution of global public goods over the long term

    Quantum spin glass in anisotropic dipolar systems

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    The spin-glass phase in the \LHx compound is considered. At zero transverse field this system is well described by the classical Ising model. At finite transverse field deviations from the transverse field quantum Ising model are significant, and one must take properly into account the hyperfine interactions, the off-diagonal terms in the dipolar interactions, and details of the full J=8 spin Hamiltonian to obtain the correct physical picture. In particular, the system is not a spin glass at finite transverse fields and does not show quantum criticality.Comment: 6 pages, 2 figures, to appear in J. Phys. Condens. Matter (proceedings of the HFM2006 conference

    'Hole-digging' in ensembles of tunneling Molecular Magnets

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    The nuclear spin-mediated quantum relaxation of ensembles of tunneling magnetic molecules causes a 'hole' to appear in the distribution of internal fields in the system. The form of this hole, and its time evolution, are studied using Monte Carlo simulations. It is shown that the line-shape of the tunneling hole in a weakly polarised sample must have a Lorentzian lineshape- the short-time half-width ξo\xi_o in all experiments done so far should be ∼E0\sim E_0, the half-width of the nuclear spin multiplet. After a time τo\tau_o, the single molecule tunneling relaxation time, the hole width begins to increase rapidly. In initially polarised samples the disintegration of resonant tunneling surfaces is found to be very fast.Comment: 4 pages, 5 figure

    Marine Evidence-based Sensitivity Assessment (MarESA) – A Guide

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    The Marine Evidence-based Sensitivity Assessment (MarESA) methodology was developed by the Marine Life Information Network (MarLIN) team at the Marine Biological Association of the UK. The following guide details the approach, its assumptions, and its application to sensitivity assessment. The guide discusses: • key terms used in sensitivity assessment; • the definitions and terms used in the MarESA approach; • its assumptions; • the definition of resistance, resilience and sensitivity; • the definition of pressures and their benchmarks; • the step by step process by which the possible sensitivity of each feature (habitat, biotope or species) to each pressure is assessed; • the interpretation and application of evidence to sensitivity assessments on a pressure by pressure basis; and • limitations in the application of sensitivity assessments in management. The MarESA methodology provides a systematic process to compile and assess the best available scientific evidence to determine each sensitivity assessment. The evidence used is documented throughout the process to provide an audit trail to explain each sensitivity assessment. Unlike other expert-based approaches, this means that the MarESA assessments can be repeated and updated. The resultant 'evidence base' is the ultimate source of information for the application of the sensitivity assessments to management and planning decisions. The MarESA dataset and MarLIN website represent the largest review of the potential effects of human activities and natural events on the marine and coastal habitats of the North East Atlantic yet undertaken

    Remarks on the k-error linear complexity of p(n)-periodic sequences

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    Recently the first author presented exact formulas for the number of 2ⁿn-periodic binary sequences with given 1-error linear complexity, and an exact formula for the expected 1-error linear complexity and upper and lower bounds for the expected k-error linear complexity, k >2, of a random 2ⁿn-periodic binary sequence. A crucial role for the analysis played the Chan-Games algorithm. We use a more sophisticated generalization of the Chan-Games algorithm by Ding et al. to obtain exact formulas for the counting function and the expected value for the 1-error linear complexity for pⁿn-periodic sequences over Fp, p prime. Additionally we discuss the calculation of lower and upper bounds on the k-error linear complexity of pⁿn-periodic sequences over Fp

    Quantum Relaxation of Magnetisation in Magnetic Particles

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    At temperatures below the magnetic anisotropy energy, monodomain magnetic systems (small particles, nanomagnetic devices, etc.) must relax quantum mechanically. This quantum relaxation must be mediated by the coupling to both nuclear spins and phonons (and electrons if either particle or substrate is conducting. We analyze the effect of each of these couplings, and then combine them. Conducting systems can be modelled by a "giant Kondo" Hamiltonian, with nuclear spins added in as well. At low temperatures, even microscopic particles on a conducting substrate (containing only 10−5010-50 spins) will have their magnetisation frozen over millenia by a combination of electronic dissipation and the "degeneracy blocking" caused by nuclear spins. Raising the temperature leads to a sudden unblocking of the spin dynamics at a well defined temperature. Insulating systems are quite different. The relaxation is strongly enhanced by the coupling to nuclear spins. At short times the magnetisation of an ensemble of particles relaxes logarithmically in time, after an initial very fast decay; this relaxation proceeds entirely via the nuclear spins. At longer times phonons take over, but the decay rate is still governed by the temperature-dependent nuclear bias field acting on the particles - decay may be exponential or power-law depending on the temperature. The most surprising feature of the results is the pivotal role played by the nuclear spins. The results are relevant to any experiments on magnetic particles in which interparticle dipolar interactions are unimportant. They are also relevant to future magnetic device technology.Comment: 30 pages, RevTex, e:mail , Submitted to J.Low Temp.Phys. on 1 Nov. 199

    Quantum Barkhausen Noise Induced by Domain Wall Co-Tunneling

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    Most macroscopic magnetic phenomena (including magnetic hysteresis) are typically understood classically. Here, we examine the dynamics of a uniaxial rare-earth ferromagnet deep within the quantum regime, so that domain wall motion, and the associated hysteresis, is dominated by large-scale quantum tunneling of spins, rather than classical thermal activation over a potential barrier. The domain wall motion is found to exhibit avalanche dynamics, observable as an unusual form of Barkhausen noise. We observe non-critical behavior in the avalanche dynamics that only can be explained by going beyond traditional renormalization group methods or classical domain wall models. We find that this ``quantum Barkhausen noise'' exhibits two distinct mechanisms for domain wall movement, each of which is quantum-mechanical, but with very different dependences on an external magnetic field applied transverse to the spin (Ising) axis. These observations can be understood in terms of the correlated motion of pairs of domain walls, nucleated by co-tunneling of plaquettes (sections of domain wall), with plaquette pairs correlated by dipolar interactions; this correlation is suppressed by the transverse field. Similar macroscopic correlations may be expected to appear in the hysteresis of other systems with long-range interactions.Comment: 11 pages, 4 figure
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