3,374 research outputs found

    Proceedings of the national workshop on footrot, Perth 19-21 August 2003

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    The financial support of Australian Wool Innovation Ltd (AWI) made it possible for representatives of a range of organisations from across Australia to meet and review ovine footrot. This national workshop held in Perth in August 2003, was the first of its kind for several years and brought together senior researchers, policy makers and producers from all States. The workshop provided an opportunity for the varied approach to footrot control across Australia to be considered in terms of a national approach to footrot control and also for individual States to review their current strategies in the light of experiences in other jurisdictions

    The Standing Wave Phenomenon in Radio Telescopes; Frequency Modulation of the WSRT Primary Beam

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    Inadequacies in the knowledge of the primary beam response of current interferometric arrays often form a limitation to the image fidelity. We hope to overcome these limitations by constructing a frequency-resolved, full-polarization empirical model for the primary beam of the Westerbork Synthesis Radio Telescope (WSRT). Holographic observations, sampling angular scales between about 5 arcmin and 11 degrees, were obtained of a bright compact source (3C147). These permitted measurement of voltage response patterns for seven of the fourteen telescopes in the array and allowed calculation of the mean cross-correlated power beam. Good sampling of the main-lobe, near-in, and far-side-lobes out to a radius of more than 5 degrees was obtained. A robust empirical beam model was detemined in all polarization products and at frequencies between 1322 and 1457 MHz with 1 MHz resolution. Substantial departures from axi-symmetry are apparent in the main-lobe as well as systematic differences between the polarization properties. Surprisingly, many beam properties are modulated at the 5 to 10% level with changing frequency. These include: (1) the main beam area, (2) the side-lobe to main-lobe power ratio, and (3) the effective telescope aperture. These semi-sinusoidsal modulations have a basic period of about 17 MHz, consistent with the natural 'standing wave' period of a 8.75 m focal distance. The deduced frequency modulations of the beam pattern were verified in an independent long duration observation using compact continuum sources at very large off-axis distances. Application of our frequency-resolved beam model should enable higher dynamic range and improved image fidelity for interferometric observations in complex fields. (abridged)Comment: 12 pages, 11 figures, Accepted for publication in A&A, figures compressed to low resolution; high-resolution version available at: http://www.astro.rug.nl/~popping/wsrtbeam.pd

    The introduction, deployment and impact of assistant practitioners in diagnostic radiography in Scotland

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    This article describes the outcomes of an evaluation of the impact of introducing Assistant Practitioners (AP) roles into imaging departments in 13 of the 14 NHS Boards in Scotland. Between 2006 and 2009 some 34 individuals were trained as APs in diagnostic radiography with 33 subsequently taking up AP posts. In 2010 NHS Education for Scotland commissioned an evaluation of the impact brought about through introduction of the diagnostic imaging AP role in imaging departments. The research found that a minority of the managers had considered the workforce implications of introducing the new roles or the supervisory arrangements that would be required. In some sites implementation of the roles had resulted in the release of radiographers for additional training and higher level activities, but in others financial constraints had limited such initiatives. Managers believed that APs had helped maintain or improve service capacity and quality

    The mouse alpha-globin cluster: A paradigm for studying genome regulation and organization

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    The mammalian globin gene clusters provide a paradigm for studying the relationship between genome structure and function. As blood stem cells undergo lineage specification and differentiation to form red blood cells, the chromatin structure and expression of the α-globin cluster change. The gradual activation of the α-globin genes in well-defined cell populations has enabled investigation of the structural and functional roles of its enhancers, promoters and boundary elements. Recent studies of gene regulatory processes involving these elements at the mouse α-globin cluster have brought new insights into the general principles underlying the three-dimensional structure of the genome and its relationship to gene expression throughout time

    Higgs mechanism as a collective effect due to extra dimension

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    A systematic analysis of the unitary electroweak model described by the higher derivative Lagrangian depending on extra dimension [1] is presented.Comment: 11 pages, no figure

    Does low-energy sweetener consumption affect energy intake and body weight? A systematic review, including meta-analyses, of the evidence from human and animal studies

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    By reducing energy density, low-energy sweeteners (LES) might be expected to reduce energy intake (EI) and body weight (BW). To assess the totality of the evidence testing the null hypothesis that LES exposure (versus sugars or unsweetened alternatives) has no effect on EI or BW, we conducted a systematic review of relevant studies in animals and humans consuming LES with ad libitum access to food energy. In 62 of 90 animal studies exposure to LES did not affect or decreased BW. Of 28 reporting increased BW, 19 compared LES with glucose exposure using a specific ‘learning’ paradigm. Twelve prospective cohort studies in humans reported inconsistent associations between LES use and Body Mass Index (-0.002 kg/m2/year, 95%CI -0.009 to 0.005). Meta-analysis of short- term randomized controlled trials (RCTs, 129 comparisons) showed reduced total EI for LES- versus sugar-sweetened food or beverage consumption before an ad libitum meal (-94 kcal, 95%CI -122 to -66), with no difference versus water (-2 kcal, 95%CI -30 to 26). This was consistent with EI results from sustained intervention RCTs (10 comparisons). Meta-analysis of sustained intervention RCTs (4 weeks to 40 months) showed that consumption of LES versus sugar led to relatively reduced BW (nine comparisons; -1.35 kg, 95%CI –2.28 to - 0.42), and a similar relative reduction in BW versus water (three comparisons; -1.24 kg, 95%CI –2.22 to -0.26). Most animal studies did not mimic LES consumption by humans, and reverse causation may influence the results of prospective cohort studies. The preponderance of evidence from all human RCTs indicates that LES do not increase EI or BW, whether compared with caloric or non-caloric (e.g., water) control conditions. Overall, the balance of evidence indicates that use of LES in place of sugar, in children and adults, leads to reduced EI and BW, and possibly also when compared with water

    Theoretical predictions for the direct detection of neutralino dark matter in the NMSSM

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    We analyse the direct detection of neutralino dark matter in the framework of the Next-to-Minimal Supersymmetric Standard Model. After performing a detailed analysis of the parameter space, taking into account all the available constraints from LEPII, we compute the neutralino-nucleon cross section, and compare the results with the sensitivity of detectors. We find that sizable values for the detection cross section, within the reach of dark matter detectors, are attainable in this framework. For example, neutralino-proton cross sections compatible with the sensitivity of present experiments can be obtained due to the exchange of very light Higgses with m_{h_1^0}\lsim 70 GeV. Such Higgses have a significant singlet composition, thus escaping detection and being in agreement with accelerator data. The lightest neutralino in these cases exhibits a large singlino-Higgsino composition, and a mass in the range 50\lsim m_{\tilde\chi_1^0}\lsim 100 GeV.Comment: Final version to appear in JHEP. References added. LaTeX, 53 pages, 23 figure

    Glassy transition in a disordered model for the RNA secondary structure

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    We numerically study a disordered model for the RNA secondary structure and we find that it undergoes a phase transition, with a breaking of the replica symmetry in the low temperature region (like in spin glasses). Our results are based on the exact evaluation of the partition function.Comment: 4 pages, 3 figure

    Quantum oscillator on complex projective space (Lobachewski space) in constant magnetic field and the issue of generic boundary conditions

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    We perform a 1-parameter family of self-adjoint extensions characterized by the parameter ω0\omega_0. This allows us to get generic boundary conditions for the quantum oscillator on NN dimensional complex projective space(CPN\mathbb{C}P^N) and on its non-compact version i.e., Lobachewski space(LN\mathcal L_N) in presence of constant magnetic field. As a result, we get a family of energy spectrums for the oscillator. In our formulation the already known result of this oscillator is also belong to the family. We have also obtained energy spectrum which preserve all the symmetry (full hidden symmetry and rotational symmetry) of the oscillator. The method of self-adjoint extensions have been discussed for conic oscillator in presence of constant magnetic field also.Comment: Accepted in Journal of Physics

    Probing the Higgs mechanism via γγ→W+W−\gamma\gamma\to W^+W^-

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    We investigate the sensitivity of the reaction γγ→W+W−\gamma\gamma\to W^+W^- to the Higgs sector based on the complete one-loop corrections in the minimal Standard Model and the gauged non-linear σ\sigma-model. While this sensitivity is very strong for the suppressed cross-section of equally polarized photons and longitudinal W bosons, it is only marginal for the dominant mode of transverse polarizations. The corrections within the σ\sigma-model turn out to be UV-finite in accordance with the absence of \log\MH terms in the Standard Model with a heavy Higgs boson.Comment: 12 pages uuencoded postscrip
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