Two-dimensional measurement of hydrocarbon fuel concentration using multiple laser-induced plasma-forming regions.

A two-dimensional measurement of fuel distribution in a gasoline spray flow was performed using multiple laser-induced plasma-forming regions. Multiple plasma-forming regions were generated by a laser sheet with a low breakdown threshold for a two-phase flow. To observe the formation of multiple laser-induced plasma-forming regions, shadowgraphs were imaged using a high-speed camera. Hydrogen and oxygen atomic emissions from the plasma-forming regions were obtained by attaching bandpass filters to the high-speed camera, and a two-dimensional visualization of the fuel distribution in the wide plasma-forming region was obtained by dividing the hydrogen line-filtered image with the oxygen line-filtered image. The result complements a novel method for two-dimensional measurement of instantaneous fuel concentration in the reacting flow by utilizing laser-induced breakdown spectroscopy (LIBS).

A prospective therapeutic comparison of simple suture repairs to massive cuff stitch repairs for treatment of small- and medium-sized rotator cuff tears.

PURPOSE: The purpose of this study was to compare the massive cuff stitch (MCS) with the simple stitch in terms of integrity at 2 years after surgery when used to repair small-sized to medium-sized full-thickness rotator cuff tears. METHODS: Seventy-one patients underwent arthroscopic repair of full-thickness rotator cuff tears between December 2004 and June 2006. The tear sizes ranged from 0.5 to 1.5 cm. The mean patient age was 53 years (range, 40 to 69 years), and the mean follow-up time was 33 months (range, 24 to 41 months). Group I (n = 35) underwent MCS repair, and group II (n = 36) underwent simple stitch repair. Results were analyzed by use of the Wilcoxon signed rank test and the Mann-Whitney test. Follow-up ultrasound was performed 24 to 41 months after repair. RESULTS: All patients showed improvements in the visual analog scale for pain, activities of daily living, and University of California, Los Angeles scores (P < .05), but there were no significant differences in scores between groups (P > .05). The satisfaction rating was similar for group I (4.7) and group II (4.3) (P > .05). The failure (retear) rate was significantly lower in group I (14.3%) than in group II (27.8%) (P < .05). CONCLUSIONS: The clinical outcomes between the MCS and simple stitch were not significantly different, but the MCS was superior to the simple stitch in maintaining repair integrity on ultrasound evaluation after arthroscopic repair of small-sized to medium-sized full-thickness rotator cuff tears. LEVEL OF EVIDENCE: Level III, prospective therapeutic comparative study.

A new integrated method for analyzing heart mechanics using a cell-hemodynamics-autonomic nerve control coupled model of the cardiovascular system.

A model of the cardiovascular system coupling cell, hemodynamics, and autonomic nerve control function is proposed for analyzing heart mechanics. We developed a comprehensive cardiovascular model with multi-physics and multi-scale characteristics that simulates the physiological events from membrane excitation of a cardiac cell to contraction of the human heart and systemic blood circulation and ultimately to autonomic nerve control. A lumped parameter model is used to compute the systemic and pulmonary circulations interacting with the cardiac cell mechanism. For autonomic control of the cardiovascular system, we used the approach suggested by Heldt et al. [2002. Computational modeling of cardiovascular response to orthostatic stress. J. Appl. Physiol. 92, 1239-1254] (Heldt model), including baroreflex and cardiopulmonary reflexes. We assumed sympathetic and parasympathetic pathways for the nerve control system. The cardiac muscle response to these reflex control systems was implemented using the activation-level changes in the L-type calcium channel and sarcoplasmic/endoplasmic reticulum calcium ATPase function based on experimental observations. Using this model, we delineated the cellular mechanism of heart contractility mediated by nerve control function. To verify the integrated method, we simulated a 10% hemorrhage, which involves cardiac cell mechanics, circulatory hemodynamics, and nerve control function. The computed and experimental results were compared. Using this methodology, the state of cardiac contractility, influenced by diverse properties such as the afterload and nerve control systems, is easily assessed in an integrated manner.