18,408 research outputs found

    Combining Ethological Thinking and Epidemiological Knowledge to Enhance the Naturalness of Organic Livestock Systems

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    Organic livestock farming places strong emphasis on conditions that allow animals to exhibit behavioural needs. This involves the provision of a natural environment and, in particular, outdoor conditions and a reliance on natural forages. Such environments also allow animals to be effectively integrated into crop production. However, there are potential disease risks associated with these conditions, with control options being partly limited by restrictions on chemoprophylactic measures. Examples from dairy and poultry production demonstrate how a basic understanding of ethology and a knowledge of disease epidemiology can enhance the welfare of animals whilst satisfying the ecological objectives of organic farming. Existing epidemiological models and published data can be used to examine the potential ensuing health hazards and control possibilities and to suggest alternatives

    The Life and Works of George Colman the Elder

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    An attempt has been made in this thesis to present a fully documented Life of Colman, based on examination of all the available material in the form of contemporary accounts, pamphlets and letters. This biography is accompanied by a short account of Colman's literary work other than play-writing, namely his essays in The Connoisseur and later periodicals, and his translations from Terence and Horace$ and by a detailed critical study of his plays, a special effort being made to estimate his indebtedness to earlier English and Continental writers. An attempt is made to ascertain the respective shares of Colman and Garrick in their joint work, The Clandestine Marriage. from the evidence afforded by their letters and by notes found among Colman's papers. A further examination is made of Colman's re-working of earlier plays for representation in his theatres; his versions are compared with the originals and with other adaptations for the eighteenth century stage. Some account, necessarily incomplete, is given of the theatrical history of his plays, and of contemporary and later criticism, drawn from newspapers, magazines and stage histories. His influence as theatrical manager and playwright, particularly the latter, is considered, especially with regard to his opposition to sentimentalism and his support of true comedy, and an attempt is made to indicate his position and the value of his contribution to British drama. An appendix contains a full bibliography of his works, of which no bibliographical account appears hitherto to have been given; a second appendix reproduces the text of the unprinted pantomime, The Genius of Nonsense, from the unique manuscript in the possession of the Henry E. Huntington Librar

    Conditional Production of Superpositions of Coherent States with Inefficient Photon Detection

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    It is shown that a linear superposition of two macroscopically distinguishable optical coherent states can be generated using a single photon source and simple all-optical operations. Weak squeezing on a single photon, beam mixing with an auxiliary coherent state, and photon detecting with imperfect threshold detectors are enough to generate a coherent state superposition in a free propagating optical field with a large coherent amplitude (α>2\alpha>2) and high fidelity (F>0.99F>0.99). In contrast to all previous schemes to generate such a state, our scheme does not need photon number resolving measurements nor Kerr-type nonlinear interactions. Furthermore, it is robust to detection inefficiency and exhibits some resilience to photon production inefficiency.Comment: Some important new results added, to appear in Phys.Rev.A (Rapid Communication

    Scattering of dislocated wavefronts by vertical vorticity and the Aharonov-Bohm effect II: Dispersive waves

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    Previous results on the scattering of surface waves by vertical vorticity on shallow water are generalized to the case of dispersive water waves. Dispersion effects are treated perturbatively around the shallow water limit, to first order in the ratio of depth to wavelength. The dislocation of the incident wavefront, analogous to the Aharonov-Bohm effect, is still observed. At short wavelengths the scattering is qualitatively similar to the nondispersive case. At moderate wavelengths, however, there are two markedly different scattering regimes according to wether the capillary length is smaller or larger than 3\sqrt{3} times depth. The dislocation is characterized by a parameter that depends both on phase and group velocity. The validity range of the calculation is the same as in the shallow water case: wavelengths small compared to vortex radius, and low Mach number. The implications of these limitations are carefully considered.Comment: 30 pages, 11 figure

    Comparison of LOQC C-sign gates with ancilla inefficiency and an improvement to functionality under these conditions

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    We compare three proposals for non-deterministic C-sign gates implemented using linear optics and conditional measurements with non-ideal ancilla mode production and detection. The simplified KLM gate [Ralph et al, Phys.Rev.A {\bf 65}, 012314 (2001)] appears to be the most resilient under these conditions. We also find that the operation of this gate can be improved by adjusting the beamsplitter ratios to compensate to some extent for the effects of the imperfect ancilla.Comment: to appear in PR

    Summary Report of AF1 to Snowmass 2021: Beam Physics and Accelerator Education within the Accelerator Frontier

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    This report summarizes the findings of the AF1 Topical Subgroup to Snowmass 2021, which investigates beam physics and accelerator education within the accelerator frontiers (AF). The report focuses primarily on opportunities for basic accelerator and beam physics, formulated into four grand challenges. In addition, the report also studies the current status of accelerator education, outreach and diversity issues. Physics limits of ultimate beams for future colliders are also briefly discussed.Comment: arXiv admin note: text overlap with arXiv:2203.0681

    A superspace formulation of Abelian antisymmetric tensor gauge theory

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    We apply a superspace formulation to the four-dimensional gauge theory of a massless Abelian antisymmetric tensor field of rank 2. The theory is formulated in a six-dimensional superspace using rank-2 tensor, vector and scalar superfields and their associated supersources. It is shown that BRS transformation rules of fields are realized as Euler-Lagrange equations without assuming the so-called horizontality condition and that a generating functional Wˉ\bar{W} constracted in the superspace reduces to that for the ordinary gauge theory of Abelian rank-2 antisymmetric tensor field. The WT identity for this theory is derived by making use of the superspace formulation and is expressed in a neat and compact form Wˉ/θ=0\partial\bar{W}/\partial\theta=0.Comment: Latex, 19pages, No fig
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