364 research outputs found

    An Einstein-Hilbert Action for Axi-Dilaton Gravity in 4-Dimensions

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    We examine the axi-dilatonic sector of low energy string theory and demonstrate how the gravitational interactions involving the axion and dilaton fields may be derived from a geometrical action principle involving the curvature scalar associated with a non-Riemannian connection. In this geometry the antisymmetric tensor 3-form field determines the torsion of the connection on the frame bundle while the gradient of the metric is determined by the dilaton field. By expressing the theory in terms of the Levi-Civita connection associated with the metric in the ``Einstein frame'' we confirm that the field equations derived from the non-Riemannian Einstein-Hilbert action coincide with the axi-dilaton sector of the low energy effective action derived from string theory.Comment: 6 pages Plain Tex (No Figures), Letter to Editor Classical and Quantum Gravit

    Effectiveness of application of methods of physical rehabilitation in patients of pasty age on osteoarthros of column diseases

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    The article studies the clinical efficacy of the use of methods of physical rehabilitation in patients with osteoarthrosis of the knee joints. The rehabilitation program included post-isometric relaxation exercises and the volume pneumopressing technique for myocorrection, which contributed to the restoration of normal blood flow in the area of the nidus, strengthening muscles and improving joint function

    Quantum Stephani Universe in vicinity of the symmetry center

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    We study a class of spherically symmetric Stephani cosmological models in the presence of a self-interacting scalar field in both classical and quantum domains. We discuss the construction of `canonical' wave packets resulting from the solutions of a class of Wheeler-DeWitt equations in the Stephani Universe. We suggest appropriate initial conditions which result in wave packets containing some desirable properties, most importantly good classical and quantum correspondence. We also study the situation from de-Broglie Bohm interpretation of quantum mechanics to recover the notion of time and compare the classical and Bohmian results. We exhibit that the usage of the canonical prescription and appropriate choices of expansion coefficients result in the suppression of the quantum potential and coincidence between classical and Bohmian results. We show that, in some cases, contrary to Friedmann-Robertson-Walker case, the bound state solutions also exist for all positive values of the cosmological constant.Comment: 22 pages, 19 figures, to appear in JCA

    Respiratory rehabilitation: a physiotherapy approach to the control of asthma symptoms and anxiety

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    OBJECTIVES: The objectives of this study were to verify the degree of anxiety, respiratory distress, and health-related quality of life in a group of asthmatic patients who have experienced previous panic attacks. Additionally, we evaluated if a respiratory physiotherapy program (breathing retraining) improved both asthma and panic disorder symptoms, resulting in an improvement in the health-related quality of life of asthmatics. METHODS: Asthmatic individuals were assigned to a chest physiotherapy group that included a breathing retraining program held once a week for three months or a paired control group that included a Subtle Touch program. All patients were assessed using the Diagnostic and Statistical Manual of Mental Disorders IV, the Sheehan Anxiety Scale, the Quality of Life Questionnaire, and spirometry parameter measurements. RESULTS: Both groups had high marks for panic disorder and agoraphobia, which limited their quality of life. The Breathing Retraining Group program improved the clinical control of asthma, reduced panic symptoms and agoraphobia, decreased patient scores on the Sheehan Anxiety Scale, and improved their quality of life. Spirometry parameters were unchanged. CONCLUSION: Breathing retraining improves the clinical control of asthma and anxiety symptoms and the health-related quality of life in asthmatic patients

    Black Holes with Weyl Charge and Non-Riemannian Waves

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    A simple modification to Einstein's theory of gravity in terms of a non-Riemannian connection is examined. A new tensor-variational approach yields field equations that possess a covariance similar to the gauge covariance of electromagnetism. These equations are shown to possess solutions analogous to those found in the Einstein-Maxwell system. In particular one finds gravi-electric and gravi-magnetic charges contributing to a spherically symmetric static Reissner-Nordstr\"om metric. Such Weyl ``charges'' provide a source for the non-Riemannian torsion and metric gradient fields instead of the electromagnetic field. The theory suggests that matter may be endowed with gravitational charges that couple to gravity in a manner analogous to electromagnetic couplings in an electromagnetic field. The nature of gravitational coupling to spinor matter in this theory is also investigated and a solution exhibiting a plane-symmetric gravitational metric wave coupled via non-Riemannian waves to a propagating spinor field is presented.Comment: 18 pages Plain Tex (No Figures), Classical and Quantum Gravit

    CMB observations in LTB universes: Part I: Matching peak positions in the CMB spectrum

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    Acoustic peaks in the spectrum of the cosmic microwave background in spherically symmetric inhomogeneous cosmological models are studied. At the photon-baryon decoupling epoch, the universe may be assumed to be dominated by non-relativistic matter, and thus we may treat radiation as a test field in the universe filled with dust which is described by the Lema\^itre-Tolman-Bondi (LTB) solution. First, we give an LTB model whose distance-redshift relation agrees with that of the concordance Λ\LambdaCDM model in the whole redshift domain and which is well approximated by the Einstein-de Sitter universe at and before decoupling. We determine the decoupling epoch in this LTB universe by Gamow's criterion and then calculate the positions of acoustic peaks. Thus obtained results are not consistent with the WMAP data. However, we find that one can fit the peak positions by appropriately modifying the LTB model, namely, by allowing the deviation of the distance-redshift relation from that of the concordance Λ\LambdaCDM model at z>2z>2 where no observational data are available at present. Thus there is still a possibility of explaining the apparent accelerated expansion of the universe by inhomogeneity without resorting to dark energy if we abandon the Copernican principle. Even if we do not take this extreme attitude, it also suggests that local, isotropic inhomogeneities around us may seriously affect the determination of the density contents of the universe unless the possible existence of such inhomogeneities is properly taken into account.Comment: 20 pages, 5 figure

    Reading educational reform with actor network theory: Fluid spaces, otherings, and ambivalences

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    In considering two extended examples of educational reform efforts, this discussion traces relations that become visible through analytic approaches associated with actor-network theory (ANT). The strategy here is to present multiple readings of the two examples. The first reading adopts an ANT approach to follow ways that all actors – human and non-human entities, including the entity that is taken to be ‘educational reform’ – are performed into being through the play of linkages among heterogeneous elements. Then, further readings focus not only on the material practices that become enacted and distributed, but also on the otherings that occur: the various fluid spaces and ambivalent belongings that create actor-network(s) but also escape them. For educational research, particularly in educational reform and policy, it is argued that ANT analyses are particularly useful to examine the complex enactments in these dynamics. That is, ANT can illuminate movements of ordering and disordering that occur through minute socio-material connections in educational interventions. ANT readings also can discern, within these attempts to order people and practices, the spaces of flux and instability that enable and protect alternate possibilities

    Cosmological constraints from lensing statistics and supernovae on the cosmic equation of state

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    We investigate observational constraints from lensing statistics and high-z type Ia supernovae on flat cosmological models with nonrelativistic matter and an exotic fluid with equation of state, px=(m/3−1)ρxp_x=(m/3 -1)\rho_x. We show that agreement with both tests at the 68% confidence level is possible if the parameter mm is low (mâ‰Č0.85m \lesssim 0.85) and 0.24â‰ČΩm0â‰Č0.380.24 \lesssim \Omega_{m0} \lesssim 0.38 with lower values of Ωm0\Omega_{m0} corresponding to higher mm. We find that a conventional cosmological constant model with Ωm0≃0.33\Omega_{m0}\simeq 0.33 is the best fit model of the combined likelihood.Comment: 7 pages, 4 postscript figures, revtex, submitted to Phys. Rev.
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