10,633 research outputs found

    Ultrasonographic identification of the dorsal atlantoaxial ligament in dogs

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    Objective: To determine the ability to identify the dorsal atlantoaxial ligament during ultrasonographic examination of dogs. Study design: Canine cadaveric study. Sample population: Canine cervical spines (n = 35). Methods: Thirty-five canine cadavers with an estimated body weight of 6-35 kg were retrieved. Five cervical spines were dissected to assess the length and thickness of the dorsal atlantoaxial ligament and correlate ultrasound-guided injection of ink with anatomical dissection. Ultrasonographic evaluation of the dorsal atlantoaxial ligament was performed on 30 cadavers. The visibility of the dorsal atlantoaxial ligament in both the transverse and the sagittal planes was subjectively scored (0-3). Results: The dorsal atlantoaxial ligament was detectable on ultrasonographic examination in all cadavers: 27/30 and 28/30 were graded as moderately visible (grade 2) or clearly visible (grade 3) in the sagittal and transverse view, respectively. Only 1/30 cadaver specimen of a large breed dog was graded as 1 (indistinct) in both the sagittal and transverse planes. None of the cadavers were graded as 0 (not visible) in any view. Conclusion: The dorsal atlantoaxial ligament can be identified in ultrasonographic examination of normal canine cadavers. Future studies on animals with clinical atlantoaxial instability/subluxation are needed to evaluate the role of this imaging technique in providing a safer diagnosis of this condition. Clinical relevance: Ultrasonographic examination of the dorsal atlantoaxial ligament could potentially provide a noninvasive and safe imaging technique that may contribute to the diagnosis of atlantoaxial instability/subluxation in dogs

    Strings in gravity with torsion

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    A theory of gravitation in 4D is presented with strings used in the material action in U4U_4 spacetime. It is shown that the string naturally gives rise to torsion. It is also shown that the equation of motion a string follows from the Bianchi identity, gives the identical result as the Noether conservation laws, and follows a geodesic only in the lowest order approximation. In addition, the conservation laws show that strings naturally have spin, which arises not from their motion but from their one dimensional structure.Comment: 16 page

    Robustness of fossil fish teeth for seawater neodymium isotope reconstructions under variable redox conditions in an ancient shallow marine setting

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    Fossil fish teeth from pelagic open ocean settings are considered a robust archive for preserving the neodymium (Nd) isotopic composition of ancient seawater. However, using fossil fish teeth as an archive to reconstruct seawater Nd isotopic compositions in different sedimentary redox environments and in terrigenous‐dominated, shallow marine settings is less proven. To address these uncertainties, fish tooth and sediment samples from a middle Eocene section deposited proximal to the East Antarctic margin at Integrated Ocean Drilling Program Site U1356 were analyzed for major and trace element geochemistry, and Nd isotopes. Major and trace element analyses of the sediments reveal changing redox conditions throughout deposition in a shallow marine environment. However, variations in the Nd isotopic composition and rare earth element (REE) patterns of the associated fish teeth do not correspond to redox changes in the sediments. REE patterns in fish teeth at Site U1356 carry a typical mid‐REE‐enriched signature. However, a consistently positive Ce anomaly marks a deviation from a pure authigenic origin of REEs to the fish tooth. Neodymium isotopic compositions of cleaned and uncleaned fish teeth fall between modern seawater and local sediments and hence could be authigenic in nature, but could also be influenced by sedimentary fluxes. We conclude that the fossil fish tooth Nd isotope proxy is not sensitive to moderate changes in pore water oxygenation. However, combined studies on sediments, pore waters, fish teeth, and seawater are needed to fully understand processes driving the reconstructed signature from shallow marine sections in proximity to continental sources

    Fermion Helicity Flip Induced by Torsion Field

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    We show that in theories of gravitation with torsion the helicity of fermion particles is not conserved and we calculate the probability of spin flip, which is related to the anti-symmetric part of affine connection. Some cosmological consequences are discussed.Comment: 6 pages, to appear in Europhysics Letter

    Torsion as electromagnetism and spin

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    We show that it is possible to formulate the classical Einstein-Maxwell-Dirac theory of spinors interacting with the gravitational and electromagnetic fields as the Einstein-Cartan-Kibble-Sciama theory with the Ricci scalar of the traceless torsion, describing gravity, and the torsion trace acting as the electromagnetic potential.Comment: 6 pages; published versio

    Echo-subject in Southern Vanuatu versus switch-reference

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    In this talk we discuss the echo subject (ES) system in Whitesands, and contrast the ES system in Whitesands — and Vanuatu ES systems in general — with the better known New Guinean type of switch reference (SR) systems. Like other Southern Vanuatu languages, Whitesands has an ES marker. The ES marker m- is used instead of a normal subject prefix when the subject of a clause is coreferential with some reference(s) of the preceding clause. The antecedent is usually the subject, but it can also be the object, an oblique, or some combinations of these. Together with a brief survey of ES systems in other Vanuatu languages, we will conclude that the ES systems in Vanuatu are used solely for the syntacto-semantic function of reference tracking. This contrasts with the New Guinean type of SR systems, which is used for both reference tracking and the discourse function of indicating participant continuity versus discontinuity. For instance, the so-called ‘same subject’ or ‘coreferential’ marker, other than indicating that some reference is coreferential with another reference, also indicates that the ‘SR pivot’ is a salient participant, and that it will remain foregrounded, or reappear in the foreground sometime later in the discourse

    Strengthening and stretching for rheumatoid arthritis of the hand (SARAH). A randomised controlled trial and economic evaluation

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    Study registration: Current Controlled Trials ISRCTN 89936343.Background - The effectiveness of exercise for improving hand and wrist function in people with rheumatoid arthritis (RA) is uncertain. Objectives - The study aims were (1) to estimate the clinical effectiveness and cost-effectiveness of adding an optimised exercise programme for hands and upper limbs to standard care for patients with RA; and (2) to qualitatively describe the experience of participants in the trial with a particular emphasis on acceptability of the intervention, exercise behaviours and reasons for adherence/non-adherence.This project was funded by the National Institute for Health Research (NIHR) Health Technology Assessment programme and will be published in full in Health Technology Assessment; Vol. 19, No. 19. See the NIHR Journals Library website for further project information. This report has been developed in association with the NIHR Collaboration for Leadership in Applied Health Research and Care Oxford and the NIHR Biomedical Research Unit Funding Scheme. This project benefited from facilities funded through Birmingham Science City Translational Medicine Clinical Research and Infrastructure Trials Platform, with support from Advantage West Midlands
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