4,233 research outputs found

    Systematic reviews of complementary therapies – an annotated bibliography. Part 2: Herbal medicine

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    Background Complementary therapies are widespread but controversial. We aim to provide a comprehensive collection and a summary of systematic reviews of clinical trials in three major complementary therapies (acupuncture, herbal medicine, homeopathy). This article is dealing with herbal medicine. Potentially relevant reviews were searched through the register of the Cochrane Complementary Medicine Field, the Cochrane Library, Medline, and bibliographies of articles and books. To be included articles had to review prospective clinical trials of herbal medicines; had to describe review methods explicitly; had to be published; and had to focus on treatment effects. Information on conditions, interventions, methods, results and conclusions was extracted using a pre-tested form and summarized descriptively. Results From a total of 79 potentially relevant reviews pre-selected in the screening process 58 met the inclusion criteria. Thirty of the reports reviewed ginkgo (for dementia, intermittent claudication, tinnitus, and macular degeneration), hypericum (for depression) or garlic preparations (for cardiovascular risk factors and lower limb atherosclerosis). The quality of primary studies was criticized in the majority of the reviews. Most reviews judged the available evidence as promising but definitive conclusions were rarely possible. Conclusions Systematic reviews are available on a broad range of herbal preparations prescribed for defined conditions. There is very little evidence on the effectiveness of herbalism as practised by specialist herbalists who combine herbs and use unconventional diagnosis

    On the Geroch-Traschen class of metrics

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    We compare two approaches to semi-Riemannian metrics of low regularity. The maximally 'reasonable' distributional setting of Geroch and Traschen is shown to be consistently contained in the more general setting of nonlinear distributional geometry in the sense of Colombea

    High-field Zeeman effect of shallow acceptors in germanium

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    Zeeman absorption spectra have been obtained for B and Ga in Ge for B∥〈100〉 in the Voigt configuration with plane-polarized radiation. All twelve allowed transitions were observed for both the G and D lines. The corresponding excited states of these two lines for both impurities behave identically; two recent theoretical results are in good agreement. The measurements are a sensitive probe of the ground states; there are differences between the behavior of these for the two acceptors

    Community rotorcraft air transportation benefits and opportunities

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    Information about rotorcraft that will assist community planners in assessing and planning for the use of rotorcraft transportation in their communities is provided. Information useful to helicopter researchers, manufacturers, and operators concerning helicopter opportunities and benefits is also given. Three primary topics are discussed: the current status and future projections of rotorcraft technology, and the comparison of that technology with other transportation vehicles; the community benefits of promising rotorcraft transportation opportunities; and the integration and interfacing considerations between rotorcraft and other transportation vehicles. Helicopter applications in a number of business and public service fields are examined in various geographical settings

    Aharonov-Bohm-like effect for light propagating in nematics with disclinations

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    Using a geometric approach for the propagation of light in anisotropic media, we investigate what effect the director field of disclinations may have on the polarization state of light. Parallel transport around the defect, of the spinor describing the polarization, indicates the acquisition of a topological phase, in analogy with the Aharonov-Bohm effect.Comment: 6 pages, to appear in Europhysics Letter

    Space-time extensions II

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    The global extendibility of smooth causal geodesically incomplete spacetimes is investigated. Denote by γ\gamma one of the incomplete non-extendible causal geodesics of a causal geodesically incomplete spacetime (M,gab)(M,g_{ab}). First, it is shown that it is always possible to select a synchronised family of causal geodesics Γ\Gamma and an open neighbourhood U\mathcal{U} of a final segment of γ\gamma in MM such that U\mathcal{U} is comprised by members of Γ\Gamma, and suitable local coordinates can be defined everywhere on U\mathcal{U} provided that γ\gamma does not terminate either on a tidal force tensor singularity or on a topological singularity. It is also shown that if, in addition, the spacetime, (M,gab)(M,g_{ab}), is globally hyperbolic, and the components of the curvature tensor, and its covariant derivatives up to order k1k-1 are bounded on U\mathcal{U}, and also the line integrals of the components of the kthk^{th}-order covariant derivatives are finite along the members of Γ\Gamma---where all the components are meant to be registered with respect to a synchronised frame field on U\mathcal{U}---then there exists a CkC^{k-} extension Φ:(M,gab)(M^,g^ab)\Phi: (M,g_{ab}) \rightarrow (\widehat{M},\widehat{g}_{ab}) so that for each γˉΓ\bar\gamma\in\Gamma, which is inextendible in (M,gab)(M,g_{ab}), the image, Φγˉ\Phi\circ\bar\gamma, is extendible in (M^,g^ab)(\widehat{M},\widehat{g}_{ab}). Finally, it is also proved that whenever γ\gamma does terminate on a topological singularity (M,gab)(M,g_{ab}) cannot be generic.Comment: 42 pages, no figures, small changes to match the published versio

    Giant and reversible extrinsic magnetocaloric effects in La0.7Ca0.3MnO3 films due to strain

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    Large thermal changes driven by a magnetic field have been proposed for environmentally friendly energy efficient refrigeration, but only a few materials which suffer hysteresis show these giant magnetocaloric effects. Here we create giant and reversible extrinsic magnetocaloric effects in epitaxial films of the ferromagnetic manganite La0.7Ca0.3MnO3 using strain mediated feedback from BaTiO3 substrates near a first-order structural phase transition. Our findings should inspire the discovery of giant magnetocaloric effects in a wide range of magnetic materials, and the parallel development of nanostructured bulk samples for practical applications.Comment: 32 pages, 1 Table, 5 figures, supplementary informatio

    Systematic reviews of complementary therapies - an annotated bibliography. Part 1: Acupuncture

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    Background Complementary therapies are widespread but controversial. We aim to provide a comprehensive collection and a summary of systematic reviews of clinical trials in three major complementary therapies (acupuncture, herbal medicine, homeopathy). This article is dealing with acupuncture. Potentially relevant reviews were searched through the register of the Cochrane Complementary Medicine Field, the Cochrane Library, Medline, and bibliographies of articles and books. To be included articles had to review prospective clinical trials of acupuncture; had to describe review methods explicitly; had to be published; and had to focus on treatment effects. Information on conditions, interventions, methods, results and conclusions was extracted using a pretested form and summarized descriptively. Results From a total of 48 potentially relevant reviews preselected in a screeening process 39 met the inclusion criteria. 22 were on various pain syndromes or rheumatic diseases. Other topics addressed by more than one review were addiction, nausea, asthma and tinnitus. Almost unanimously the reviews state that acupuncture trials include too few patients. Often included trials are heterogeneous regarding patients, interventions and outcome measures, are considered to have insufficient quality and contradictory results. Convincing evidence is available only for postoperative nausea, for which acupuncture appears to be of benefit, and smoking cessation, where acupuncture is no more effective than sham acupuncture. Conclusions A large number of systematic reviews on acupuncture exists. What is most obvious from these reviews is the need for (the funding of) well-designed, larger clinical trials

    Complex actions in two-dimensional topology change

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    We investigate topology change in (1+1) dimensions by analyzing the scalar-curvature action 1/2RdV1/2 \int R dV at the points of metric-degeneration that (with minor exceptions) any nontrivial Lorentzian cobordism necessarily possesses. In two dimensions any cobordism can be built up as a combination of only two elementary types, the ``yarmulke'' and the ``trousers.'' For each of these elementary cobordisms, we consider a family of Morse-theory inspired Lorentzian metrics that vanish smoothly at a single point, resulting in a conical-type singularity there. In the yarmulke case, the distinguished point is analogous to a cosmological initial (or final) singularity, with the spacetime as a whole being obtained from one causal region of Misner space by adjoining a single point. In the trousers case, the distinguished point is a ``crotch singularity'' that signals a change in the spacetime topology (this being also the fundamental vertex of string theory, if one makes that interpretation). We regularize the metrics by adding a small imaginary part whose sign is fixed to be positive by the condition that it lead to a convergent scalar field path integral on the regularized spacetime. As the regulator is removed, the scalar density 1/2gR1/2 \sqrt{-g} R approaches a delta-function whose strength is complex: for the yarmulke family the strength is β2πi\beta -2\pi i, where β\beta is the rapidity parameter of the associated Misner space; for the trousers family it is simply +2πi+2\pi i. This implies that in the path integral over spacetime metrics for Einstein gravity in three or more spacetime dimensions, topology change via a crotch singularity is exponentially suppressed, whereas appearance or disappearance of a universe via a yarmulke singularity is exponentially enhanced.Comment: 34 pages, REVTeX v3.0. (Presentational reorganization; core results unchanged.
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