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IMV is a combination of spontaneous and mechanical ventilation. For numerous reasons, IMV is potentially more advantageous than conventional techniques. By maintaining spontaneous breathing, mechanical augmentation can be titrated to adjust alveolar minute ventilation levels to normal, thereby decreasing the incidence of respiratory alkalemia. There are major differences between the cardiopulmonary effects of IMV and conventional mechanical ventilation. Spontaneous inspiration decreases Ppl and results in better distribution of inspired gas, a better V/Q, and less physiological dead space. In addition, transmural filling pressures, venous return, and cardiac output are more normal than during conventional mechanical ventilation. Maintenance of spontaneous ventilation lowers mean Paw and pulmonary vascular resistance. If venous admixture occurs, it can be minimized by titrating PEEP. Thus, more effective therapy for hypoxemia is possible. If spontaneous breathing is to persist and be efective, work-of-breathing must be minimized. This can be accomplished best when a continuous flow of gas provides optimal CPAP to maintain FRC and to minimize the effects of decreased compliance without depressing cardiac function.  相似文献   
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Rick Downs 《电子设计技术》2007,14(6):172-172,174
运算放大器输出级极限 运算放大器的轨至轨运行是指其输入级或输出级,或者是指其输入级与输出级.作为驱动SAR ADC输入端的一个缓冲器,我们更关注运算放大器轨至轨的输出能力.  相似文献   
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In this article a method of computing multiparameter finite change sensitivities is derived. The method is conceptually simpler than existing techniques and, for certain applications, computationally more efficient.  相似文献   
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An industrial and academic perspective on plantwide control   总被引:1,自引:0,他引:1  
The purpose of this paper is to stress the importance of selecting the right plantwide control structure and the need for a formalized approach that can encompass the many issues that arise in plantwide control design. Since the concept of process control design based on a holistic view of the process came about, the variety of procedures and approaches to the design problem has illustrated the difficulty of a unified approach. Using examples, the need and advantages of using a systematic approach based on considering the plant economics are highlighted. The examples deal with disturbance rejection, throughput maximization and economic optimization of plants consisting of parallel units.  相似文献   
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Rick Downs 《电子设计技术》2005,12(9):i0051-i0052
触摸屏被有效应用于多种信息设备中,如个人教字助理(PDA)以及用于仪表与控制应用领域的通用指示器等。从触摸屏获取信息,井将这些信息传辅至德处理器是一项复杂的难题。本文将介绍电阻式触摸屏的基本工作原理,以及如何高效地将这些模拟辅入信息转换为可用的教字信息,井将解决诸如建立时间、噪声过滤以及速度权衡等问题。  相似文献   
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Combination therapy with intravesical bacillus Calmette-Guérin (BCG) plus IFN-alpha for superficial bladder cancer has been demonstrated to be more effective than either single agent alone in animal studies and of suggested greater efficacy in clinical studies. However, the mechanism by which IFN-alpha enhances BCG-mediated antitumor activity is poorly understood. Using PBMCs from bladder cancer patients, IFN-alpha was found to substantially enhance the efficacy of BCG to induce IFN-gamma production. Among 34 patients tested, 80% showed >4-fold increase. This effect of IFN-alpha was observed in both initial and memory responses to BCG. In addition, IFN-alpha up-regulated BCG-induced IL-12 and TNF-alpha and down-regulated BCG-induced IL-10. Neutralizing endogenous IL-10 or adding exogenous IL-12 provided further synergy for IFN-gamma production. In clinical practice, intravesical IFN-alpha 2B (50 million units (MU)/dose) was observed to accelerate urinary IFN-gamma production to low-dose BCG (one-tenth or one-third of a full dose) in patients treated with combination therapy compared with BCG alone. These results suggest that IFN-alpha is a potent BCG enhancer that polarizes the BCG-induced immune response toward the cellular immune pathway by promoting Th1 cytokine expression and reducing Th2 cytokine expression. This study provides an immunological basis for future rational use of IFN-alpha in conjunction with intravesical BCG for bladder cancer immunotherapy.  相似文献   
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Ultrasonic inspection of tires has previously been performed using low frequencies in air, which results in low spatial resolution. In addition, the tire has not typically been completely inspected. The limited scanning area and scanning resolution in previous work has been the result of difficulties in acquiring and handling large data sets, difficulties in positioning transducers in a large number of locations over a complex shape, and display or interpretation of the large amount of data which would be generated in such a system. A new design is presented which combines a low-cost multiple processor design to perform motion control, data acquisition, and data transfer. The design is generally useful in a number of different nondestructive evaluation and other large-data-set data acquisition and control applications  相似文献   
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