Nicholas C. Miller

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A mathematical model of the circulatory system based on the principles of venous return is described and applied to the condition of acceleration stress. The model consists of two single compartments representing the pulmonary and systemic portions of the circulatory system. During periods of acceleration stress the pressure in the systemic compartment,(More)
A new cascade impactor has been designed specifically for pharmaceutical inhaler testing. This impactor, called the Next Generation Pharmaceutical Impactor (NGI), has seven stages and is intended to operate at any inlet flow rate between 30 and 100 L/min. It spans a cut size (D50) range from 0.54-microm to 11.7-microm aerodynamic diameter at 30 L/min and(More)
The calibration of the first stage of the twin-stage impinger, an instrument proposed for use in measuring the spray size from metered-dose inhalers, was performed with monodisperse aerosols by a standard technique for cascade impactors. The mean cut point was found to be not particularly sensitive to operating variables which may be expected to occur in(More)
Design theory for cascade impactors is well developed, and design principles can be summarized quite succinctly. The key geometric parameters of three commonly used impactors have been compared to design guidelines. Calibration theory and practice have undergone improvement in recent years. Published results show distinctly different characteristics for(More)
Purpose. This work was performed in order to compare and contrast results obtained from cascade impactor measurements on metered dose inhalers (MDIs) using a variety of inlet ports. Methods. The collection characteristics of four cascade impactor ports (a physical model of the human throat, a simplified geometry intended to mimic the physical model, and two(More)
Purpose. The purpose of this study is to investigate the effect of drug load, the coating of impactor stages, and the design of cascade impactors on albuterol MDIs particle size distribution measurements. The results of the investigation will be used to explain the 'loading effect' recently reported. Methods. Particle size distribution parameters of a(More)
A new test method is described for assessing the loss of prime in metered-dose aerosols. Two representative metered-dose valve designs and two storage positions were used to assess the utility of this test method at three different sites. Loss of prime, defined as a valve delivery 15% below the mean, was detected in three of the four test configurations.(More)
The analysis of fields in periodic dielectric structures arise in numerous applications of recent interest, ranging from photonic bandgap structures and plasmonically active nanostructures to metamaterials. To achieve an accurate representation of the fields in these structures using numerical methods, dense spatial discretization is required. This, in(More)
One sub-field of Genetic Programming (GP) which has gained recent interest is semantic GP, in which programs are evolved by manipulating program semantics instead of program syntax. This paper introduces a new semantic GP algorithm, called SGP+, which is an extension of an existing algorithm called SGP. New crossover and mutation operators are introduced(More)
A mathematical model is derived that describes oxygen concentration in a retinal capillary in terms of the local rate of oxygen utilization and arterial pressure at eye level. The model is applied to describe the loss of vision that occurs upon exposure to acceleration stress. As applied to animals, the model provides a qualitative explanation for the(More)