4,775 research outputs found

    Supersonic wings with significant leading-edge thrust at cruise

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    Experimental/theoretical correlations are presented which show that significant levels of leading edge thrust are possible at supersonic speeds for certain planforms which match the theoretical thrust distribution potential with the supporting airfoil geometry. The analytical process employed spanwise distribution of both it and/or that component of full theoretical thrust which acts as vortex lift. Significantly improved aerodynamic performance in the moderate supersonic speed regime is indicated

    Estimating the causal effect of a time-varying treatment on time-to-event using structural nested failure time models

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    In this paper we review an approach to estimating the causal effect of a time-varying treatment on time to some event of interest. This approach is designed for the situation where the treatment may have been repeatedly adapted to patient characteristics, which themselves may also be time-dependent. In this situation the effect of the treatment cannot simply be estimated by conditioning on the patient characteristics, as these may themselves be indicators of the treatment effect. This so-called time-dependent confounding is typical in observational studies. We discuss a new class of failure time models, structural nested failure time models, which can be used to estimate the causal effect of a time-varying treatment, and present methods for estimating and testing the parameters of these models

    Supersonic aircraft Patent

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    Design of supersonic aircraft with novel fixed, swept wing planfor

    A comparison of the clinical populations of the Oregon Optometric Center and the Pacific University Optometric Clinics

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    This is a study comparing the populations of two optometric clinics. The purpose of this study is to present a statistical comparison of the Oregon Optometric Center and the Pacific University Optometric Clinic. A questionnaire was completed by Junior and Senior Optometry. Students to record these differences. The results showed significant differences between the two populations as to the patient\u27s last visual examination, last medical or dental examination, residence, education, entrance habitual visual acuity, presbyopic near prescripti on, and the near nonpresbyopic prescription. Recommendations are included for present use and further study
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