1,139 research outputs found

    Evidence and Narrative

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    Mad Cow Disease: An Approach to its Containment

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    When is Freshman\u27s Dream Actually True?

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    We address the problem of determining what points in a field satisfy Freshman\u27s Dream, or equivalently, when a monomial behaves additively. It is conjectured that the only additive points over the rational numbers are trivial. In the case of finite fields, we generalize well-known results about uni-variate polynomials to bivariate homogeneous polynomials in order to count the number of additive points

    Oracle Database 10g: a beginner's guide

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    Regression of ranked responses when raw responses are censored

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    We discuss semiparametric regression when only the ranks of responses are observed. The model is Yi=F(xi′β0+εi)Y_i = F (\mathbf{x}_i'{\boldsymbol\beta}_0 + \varepsilon_i), where YiY_i is the unobserved response, FF is a monotone increasing function, xi\mathbf{x}_i is a known p−p-vector of covariates, β0{\boldsymbol\beta}_0 is an unknown pp-vector of interest, and εi\varepsilon_i is an error term independent of xi\mathbf{x}_i. We observe {(xi,Rn(Yi)):i=1,…,n}\{(\mathbf{x}_i,R_n(Y_i)) : i = 1,\ldots ,n\}, where RnR_n is the ordinal rank function. We explore a novel estimator under Gaussian assumptions. We discuss the literature, apply the method to an Alzheimer's disease biomarker, conduct simulation studies, and prove consistency and asymptotic normality.Comment: 33 pages, 6 figure

    Integrating the Base of Aircraft Data (BADA) in CTAS Trajectory Synthesizer

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    The Center-Terminal Radar Approach Control (TRACON) Automation System (CTAS), developed at NASA Ames Research Center for assisting controllers in the management and control of air traffic in the extended terminal area, supports the modeling of more than four hundred aircraft types. However, 90% of them are supported indirectly by mapping them to one of a relatively few aircraft types for which CTAS has detailed drag and engine thrust models. On the other hand, the Base of Aircraft Data (BADA), developed and maintained by Eurocontrol, supports more than 300 aircraft types, about one third of which are directly supported, i.e. they have validated performance data. All these data were made available for CTAS by integrating BADA version 3.8 into CTAS Trajectory Synthesizer (TS). Several validation tools were developed and used to validate the integrated code and to evaluate the accuracy of trajectory predictions generated using CTAS "native" and BADA Aircraft Performance Models (APM) comparing them with radar track data. Results of these comparisons indicate that the two models have different strengths and weaknesses. The BADA APM can improve the accuracy of CTAS predictions at least for some aircraft types, especially small aircraft, and for some flight phases, especially climb
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