The cells of the sinoatrial node (SAN) are self-excitable entities that show a coupled electrical pattern that consists of the synchronized activation of action potentials that determine the heart rate. To accurately describe the behavior of cell membrane proteins, theoretical biophysicists have devoted themselves to the study of the electrical activity of individual cells, which involves solving a large number of coupled differential equations. This computational limitation makes the modeling of a large number of cells unattainable, since the intracellular distribution of Ca 2+ must be considered and this fact increases in grand extent the number of differential equations involved. In this work, we explore different parallel architectures (using OpenMP, MPI, and CUDA libraries) to show advances in the computational modeling and simulation of the SAN using a multicellular array in which the cells are endowed of heterogeneous conductances and are electrically coupled, considering a variable connectivity among them.
Abstract. In [24] we studied the transitional zone between Sinoatrial cells and Atrial cells in the Heart. The present paper study the mechanisms underlying the dynamics of the modeled nets in that paper.
Introduction: Nowadays, childhood diseases as Duchenne muscular dystrophy (DMD) have raised interest in pediatric bone densitometry, since long-term steroid therapy is a serious risk factor for osteoporosis. Even though dual energy X-ray absorptiometry (DXA) is the most used technique to measure bone mineral density (BMD), quantitative computed tomography (QCT) is the most exact way to assess bone health. But the reference values are available for adult populations, and only for a few pediatric populations. Objective: The aim of this study is to measure volumetric BMD (vBMD) values using QCT to determine the reference values of healthy Mexican pediatric population. Material and methods: This is an observational transversal study to measure vBMD from three images of healthy trabecular lumbar spine using QCT. Results: vBMD data has a sigmoid behavior in both genders, with a delayed start for males; the difference in values during puberty have a moderate significant correlation (-0.546, p = 0.004). vBMD values for both genders are 40% lower than the reported for Caucasian pediatric population. Conclusion: These results encourage us to continue this study to increase the confidence of the obtained vBMD reference values for Mexican pediatric population. This will have a high impact in diagnosis accuracy, particularly in chronically ill children, with DMD and other musculoskeletal diseases.
ResumenIntroducción: En la actualidad, enfermedades infantiles como la distrofia muscular de Duchenne (DMD) han despertado el interés en la densitometría ósea pediátrica, ya que la terapia con esteroides a largo plazo es un factor de riesgo grave para la osteoporosis. Aunque la absorciometría de rayos X de energía dual (DXA) es la técnica más utilizada para medir la densidad mineral ósea (DMO), la tomografía computarizada cuantitativa (QCT) es la forma más exacta de evaluar la salud ósea. Pero los valores de referencia están disponibles para poblaciones adultas y solo para unas pocas poblaciones pediátricas. Objetivo: El objetivo de este estudio es medir los valores de DMO volumétrica (vDMO) utilizando QCT para determinar los valores de referencia de la población pediátrica mexicana sana. Material y métodos: Este es un estudio transversal observacional para medir vDMO a partir de tres imágenes de
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