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F Sagues

Publications and source records attributed to F Sagues.

7 recordsLinked to original sources
PubMed2000

Brownian motion of spiral waves driven by spatiotemporal structured noise

Spiral chemical waves subjected to a spatiotemporal random excitability are experimentally and numerically investigated in relation to the light-sensitive Belousov-Zhabotinsky reaction. Brownian motion is identified and characterized by an effective diffusion coefficient which shows a rather complex dependence on the time and length scales of the noise relative to those of the spiral. A kinematically based model is proposed whose results are in good qualitative agreement with experiments and numerics.

Journal Article↗
PubMed2000

Particle dispersion in synthetic turbulent flows

We study particle dispersion advected by a synthetic turbulent flow from a Lagrangian perspective and focus on the two-particle and cluster dispersion by the flow. It has been recently reported that Richardson's law for the two-particle dispersion can stem from different dispersion mechanisms, and can be dominated by either diffusive or ballistic events. The nature of the Richardson dispersion depends on the parameters of our flow and is discussed in terms of the values of a persistence parameter expressing the relative importance of the two above-mentioned mechanisms. We support this analysis by studying the distribution of interparticle distances, the relative velocity correlation functions, as well as the relative trajectories.

Journal Article↗
PubMed2000

Lifetime enhancement of scroll rings by spatiotemporal fluctuations

The dynamics of three-dimensional scroll rings with spatiotemporal random excitability is investigated numerically using the FitzHugh-Nagumo model. Depending on the correlation time and length scales of the fluctuations, the lifetime of the ring filament is enlarged and a resonance effect between the time scale of the scroll ring and the time correlation of the noise is observed. Numerical results are interpreted in terms of a simplified stochastic model derived from the kinematical equations for three-dimensional excitable waves.

Journal Article↗
PubMed1985

Electrocardiographic and vectorcardiographic study of interatrial conduction disturbances with left atrial retrograde activation.

From 81,000 ECGs we collected 83 cases that fulfilled the criteria of Interatrial Conduction Disturbances with Left Atrial Retrograde Activation (IACD-LARA) (P +/- in II, III and VF with P width greater than or equal to 120 msec.). We present the detailed study of 35 cases with surface ECG and VCG and 29 cases with orthogonal ECG leads. The results are then compared against two control groups: with cardiopathy (30 cases) and without cardiopathy (25 cases). The prevalence of IACD-LARA was nearly 1% globally, and 2% among patients with valvular heart disease. The diagnostic criteria for IACD-LARA are: 1) ECG: P +/- in II, III and VF with P greater than or equal to 120 msec. with open angle (usually greater than 90 degrees) between the first and the second part of the P.2) Orthogonal ECG: P +/- in Y lead with a negative mode greater than 40 msec. 3) VCG: More than 50 msec. above the X or Z axis, duration of the P loop greater than or equal to 110 msec., open angle between the two parts of the P loop in both frontal (131.3 degrees +/- 32.3) and right sagital planes (171.2 degrees +/- 15.1), and presence of notches and slurrings in the last part of the P loop.

Adult↗
PubMed1985

Holter ECG study of the electrocardiographic phenomena in Prinzmetal angina attacks with emphasis on the study of ventricular arrhythmias.

The ECG phenomena in 20 outpatients (121 episodes) suffering from variant angina with transient ST segment elevation greater than 1.5 mm. (Prinzmetal angina) were studied by Holter monitoring. The most important changes in the ECG morphology were: a) increased height of the R wave in all cases, b) the S wave decreased or disappeared, c) the ST segment elevation varied from 1.5 to 38 mm, d) the TQ interval was ascending in 78 episodes, e) there was a double alternance of ST-TQ in 20 episodes and f) the first modification of the ECG was an increase of the T wave height. Arrhythmias were seen in 19 patients (44 episodes). The most frequent were premature ventricular contractions. The prevalence and importance of the ventricular arrhythmias were statistically related to the duration of the episodes (p less than 0.005), the degree of the ST segment elevation (p less than 0.005), the presence of ST-TQ alternance (p less than 0.005) and the presence of increased R wave greater than 25% (p less than 0.025).

Angina Pectoris, Variant↗