Sources of variability in defining the normal range for left ventricular (LV) motion from contrast ventriculograms were assessed by comparing the function of 183 normal patients from six sites in three countries. Wall motion was measured using the centreline method at seven regions around the LV contour. The influence of institution, heart rate, age, end diastolic volume, body surface area and gender was evaluated using univariate analysis, and then compared using multivariate regression analysis. Wall motion varied significantly but weakly (|r| < 0.32 for all) with site, gender and body surface area in some regions. Variability was greater within sites than between sites. Wall motion was most similar in the two sites with the largest patient populations (N = 49 and N = 52). Normal LV wall motion is influenced by many factors. The reliable definition of the normal range requires analysis of a large number of subjects. For wall motion, the normal population should comprise closer to 50 subjects than the 10-20 that are commonly referenced.
Close to melting transitions it is possible to propagate solitary electromechanical pulses which reflect many of the experimental features of the nerve pulse including mechanical dislocations and reversible heat production. Here we show that one also obtains the possibility of periodic pulse generation when the boundary condition for the nerve is the conservation of the overall length of the nerve. This condition generates an undershoot beneath the baseline ('hyperpolarization') and a 'refractory period', i.e., a minimum distance between pulses. In this paper, we outline the theory for periodic solutions to the wave equation and compare these results to action potentials from the femoral nerve of the locust (locusta migratoria). In particular, we describe the frequently occurring minimum-distance doublet pulses seen in these neurons and compare them to the periodic pulse solutions.corresponding authors: E. Villagran Vargas (villagran.e@gmail.com) and T.
We consider certain approximation for determining the equation of motion for nerve signals by using the model of the lipid melting of membranes. The nerve pulses are found to display nonlinearity and dispersion during the melting transition. In this
ResumenNosotros hemos analizado una aproximación analítica para determinar la ecuación del movimiento de pulsos nerviosos usando el modelo del disolución del lípido en membranas. Los pulsos nerviosos muestran no linealidad y dispersión durante su transición fundente. En este modelo simplificado la ecuación inicial no lineal propuesta por Heimburg y colaboradores se transformó en la conocida ecuación no lineal integrable de Boussinesq. Bajo valores específicos de los parámetros del espacio este Sistema muestra la existencia de estructuras solitónicas singulares y regulares. Después de sus colisiones durante su propagación, fueron observados la creación y el aniquilamiento mutuo (de uno con el otro) de los pulsos a lo largo del nervio.Palabras claves: Ecuación de Boussinesq, solitones singulares, neuronas únicas, código neuronal.
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