What gross weight and range for an advanced HSCT?

A review of studies conducted in 1986 indicates that a 300 passenger, 5500 nautical mile range aircraft should weigh less than 400,000 pounds. Some data from a British Aerospace Society of Automotive Engineers (SAE) paper will be shown that purport to be an advanced Concorde that meets the range payload specifications at a gross weight of 360,000 pounds. Previous studies by Peter Coen of Langley Research Center support these results. The weight of a supersonic transport is important from the point of view of how much effort should be expended in developing lower sonic boom technologies. It is obvious that a 360,000 pound aircraft can be modified to a more acceptable boom level than a 700,000 pound one

The Evolution of Ellipticals, Spirals and Irregulars: Overcoming Selection Bias

The Hubble Deep Fields represent our best opportunity for probing galaxy evolution over a substantive look-back time. However as with any dataset the HDFs are prone to selection biases. These biases are extremely severe beyond z \~1.25 such that a meaningful interpretation of generic galaxy evolution is not possible. We can however extract well defined volume-limited samples at z < 1. The data are entirely consistent with passive/null-evolution for ellipticals, spirals and irregulars however this concluion is tempered by small number statistics. Alas stringent constraints on galaxy evolution await an order of magnitude increase in the number of HDFs.Comment: To appear in Proc. of the ESO/ECF/STSCI workshop on Deep Fields, Garching Oct 2000, (Publ: Springer

Riemann-Hilbert analysis for Jacobi polynomials orthogonal on a single contour

Classical Jacobi polynomials $P_{n}^{(\alpha,\beta)}$, with $\alpha, \beta>-1$, have a number of well-known properties, in particular the location of their zeros in the open interval $(-1,1)$. This property is no longer valid for other values of the parameters; in general, zeros are complex. In this paper we study the strong asymptotics of Jacobi polynomials where the real parameters $\alpha_n,\beta_n$ depend on $n$ in such a way that $$\lim_{n\to\infty}\frac{\alpha_{n}}{n}=A, \quad \lim_{n\to\infty}\frac{\beta_{n}}{n}=B,$$ with $A,B \in \mathbb{R}$. We restrict our attention to the case where the limits $A,B$ are not both positive and take values outside of the triangle bounded by the straight lines A=0, B=0 and $A+B+2=0$. As a corollary, we show that in the limit the zeros distribute along certain curves that constitute trajectories of a quadratic differential. The non-hermitian orthogonality relations for Jacobi polynomials with varying parameters lie in the core of our approach; in the cases we consider, these relations hold on a single contour of the complex plane. The asymptotic analysis is performed using the Deift-Zhou steepest descent method based on the Riemann-Hilbert reformulation of Jacobi polynomials.Comment: 37 pages, 10 figure

Understanding Equitable Assessment: How Preservice Teachers Make Meaning of DisAbility

Disproportionality of historically marginalized populations in special education continues to be a critical concern. The identification of students with disabilities is reliant on valid and reliable assessment that is free of bias. The extent to which this is possible given measurement constraints and an increasingly diverse student population is unclear. How teachers are trained to design, select, administer, score, and interpret assessment data related to the identification of students with disabilities is vastly under-researched considering the significant implications of assessment practices. In this study, six special education preservice teachers engaged in an assessment methods course during their second semester of an initial certification program. This study focuses on shifts in preservice teacher understanding and the associated learning experiences in the course. Findings from this study have the potential to inform general and special education teacher preparation coursework