9,694 research outputs found

    Images in clinical medicine. Percutaneous mitral valvuloplasty

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    Geomorfología litoral y significación de las variacones del nivel del mar

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    Depto. de Geodinámica, Estratigrafía y PaleontologíaFac. de Ciencias GeológicasTRUEpu

    A Derivation of Three-Dimensional Inertial Transformations

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    The derivation of the transformations between inertial frames made by Mansouri and Sexl is generalised to three dimensions for an arbitrary direction of the velocity. Assuming lenght contraction and time dilation to have their relativistic values, a set of transformations kinematically equivalent to special relativity is obtained. The ``clock hypothesis'' allows the derivation to be extended to accelerated systems. A theory of inertial transformations maintaining an absolute simultaneity is shown to be the only one logically consistent with accelerated movements. Algebraic properties of these transformations are discussed. Keywords: special relativity, synchronization, one-way velocity of light, ether, clock hypothesis.Comment: 16 pages (A5), Latex, one figure, to be published in Found. Phys. Lett. (1997

    Conversion of supraventricular arrhythmias to sinus rhythm using flecainide

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    We evaluated the efficacy of flecainide acetate (given intravenously to a maximal dose of2 mg kg−1 and then orally in a dose of 100 mg b.d. or 100 mg t.d.s.) in the conversion to sinus rhythm of 50 patients exhibiting supraventricular arrhythmias (39 with atrial fibrillation, 6 with atrial flutter, 4 with supraventricu tachycardia and onewith supraventricular tachycardia in association with the Wolff—Parkinson—White syndrome). Conversion was achieved in 36 patients (72%) (29 cases with atrial fibrillation, 4 cases with supraventricular tachycardia, 2 cases with atrial flutter and one case with Wolff—Parkinson-White syndrome), over a mean period of 7.4 ± 9 h. The patients in which conversion was achieved had arrhythmias which had been in existence for a shorter time (5.3 ± 9.8 days) than those in which conversion was not achieved (16.7 ± 26.2 days) (P<0.01). The mean dosage of flecainide used to achieve conversion was 2.5 ± 2.36 mg kg−1. Flecainide appears to be an effective agent for the conversion to sinus rhythm of atrial fibrillation and supraventricular tachycardias. Its efficacy in cases of atrial flutter has not yet been demonstrate

    Análisis de secuencias de islas barrera pleistocenas en relación con variaciones del nivel del mar, laguna de La Mata (Alicante)

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    En la laguna de La Mata (Alicante) se estudia un complejo de cordones litorales pleistocenos que forman el cierre de la actual laguna. Se analizan las secuencias resultantes y los posibles indicadores de variaciones del nivel del mar. Asimismo se interpretan estos depósitos en base a una curva aparente de tendencias del nivel del mar, obtenida con la suma de las componentes eustáticas cíclicas y la componente relativa debida al factor tectónico aplicado. [ABSTRACT] A complex of Pleistocene coastal barriers is studied in La Mata lagoon (Alicante). The resuting sequences are analyzed in order to establish indicators 0f sea level changes. These deposits can be correlated with an apparent curve of sea level tendencies obtained with the sum of the cyclic eustatic component and the relative component due to the tectonic factor applied

    Instrumentation for Millimeter-wave Magnetoelectrodynamic Investigations of Low-Dimensional Conductors and Superconductors

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    We describe instrumentation for conducting high sensitivity millimeter-wave cavity perturbation measurements over a broad frequency range (40-200 GHz) and in the presence of strong magnetic fields (up to 33 tesla). A Millimeter-wave Vector Network Analyzer (MVNA) acts as a continuously tunable microwave source and phase sensitive detector (8-350 GHz), enabling simultaneous measurements of the complex cavity parameters (resonance frequency and Q-value) at a rapid repetition rate (approx. 10 kHz). We discuss the principal of operation of the MVNA and the construction of a probe for coupling the MVNA to various cylindrical resonator configurations which can easily be inserted into a high field magnet cryostat. We also present several experimental results which demonstrate the potential of the instrument for studies of low-dimensional conducting systems.Comment: 20 pages including fig
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