Browsing by Author "FERNANDEZ, C"

Now showing 1 - 9 of 9
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    ENERGY DECAY-RATES AND THE DYNAMICAL VONKARMAN EQUATIONS
    (1994) ASTABURUAGA, MA; FERNANDEZ, C; MENZALA, GP
    We find uniform rates of decay of the solutions of the dynamical von Karman equations in the presence of dissipative effects. Our proof is elementary and uses ideas of a recent technique due to E. Zuazua while studying nonlinear dissipative wave equations [1].
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    HUYGENS PRINCIPLE AND SEMILINEAR WAVE-EQUATIONS
    (PERGAMON-ELSEVIER SCIENCE LTD, 1988) ASTABURUAGA, MA; FERNANDEZ, C; MENZALA, GP
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    KICKED DYNAMICS ON HILBERT-SPACES - A NONSTANDARD APPROACH
    (AMER INST PHYSICS, 1995) BERTOGLIO, N; FERNANDEZ, C
    The main purpose of this work is to provide a rigorous interpretation of kicked models, with the aid of nonstandard analysis. These modes are represented by evolution equations involving Dirac's delta functions of time and the method used consists of approximating them by smooth functions on the *R. (C) 1995 American Institute of Physics.
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    LOCAL SMOOTHING EFFECTS FOR A NONLINEAR TIMOSHENKO TYPE EQUATION
    (PERGAMON-ELSEVIER SCIENCE LTD, 1994) ASTABURUAGA, MA; FERNANDEZ, C; MENZALA, GP
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    MATERNAL HEMODYNAMIC ADJUSTMENTS IN IDIOPATHIC FETAL GROWTH-RETARDATION
    (KARGER, 1993) ROSSO, P; DONOSO, E; BRAUN, S; ESPINOZA, R; FERNANDEZ, C; SALAS, SP
    The hemodynamic characteristics of 11 normotensive gravidas with idiopathic fetal growth retardation (FGR), were compared with 11 controls of similar age, parity and body size. At weeks 36-38 of gestation, plasma volume was 3,161 +/- 121 ml in controls and 2,624 +/- 95 ml in the FGR group (p < 0.003); cardiac output (CO) was 6,191 +/- 132 ml/min in controls and 5,483 +/- 186 ml/min in the FGR group (p < 0.01). Total peripheral vascular resistance (TPVR) was lower in controls than in FGR (1,031 +/- 33 vs. 1,306 +/- 62 dyn/s/cm5; p < 0.001). Birth weight was correlated with both plasma volume (r = 0.61; p < 0.01) and CO (r = 0.53; p < 0.02) and inversely correlated with TPVR (r = -0.69; p < 0.001). These results are in line with the hypothesis that a reduced plasma volume leads to a lower CO and, secondarily, to reduced uterine blood flow and FGR.
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    NEWTONIAN SCATTERING IN HILBERT-SPACE
    (ACADEMIC PRESS INC JNL-COMP SUBSCRIPTIONS, 1990) ASTABURUAGA, MA; FERNANDEZ, C; CORTES, V
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    NON-AUTONOMOUS CLASSICAL SCATTERING
    (ACADEMIC PRESS INC JNL-COMP SUBSCRIPTIONS, 1988) ASTABURUAGA, MA; FERNANDEZ, C; CORTES, VH
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    THE DIRECT AND INVERSE PROBLEM IN NEWTONIAN SCATTERING
    (ROYAL SOC EDINBURGH, 1991) ASTABURUAGA, MA; FERNANDEZ, C; CORTES, VH
    In this paper we study the direct and inverse scattering problem on the phase space for a classical particle moving under the influence of a conservative force. We provide a formula for the scattering operator in the one-dimensional case and we settle the properties of the potential that can be deduced from it. We also study the question of recovering the shape of the barriers which can be seen from -infinity and infinity. An example is given showing that these barriers are not uniquely determined by the scattering operator.