Orifice plates in a shock tube

This note points out some interesting aspects of a recent study of the flow resulting from the use of area change near the diaphragm of a shock tube. (1) Earlier studies (2,3) have been directed toward the use of area change for increasing the available shock speed, and thus have considered geometries where A4/A1 > 1 and A*/A1 = 1 [see notation on Fig. 1(a)]. In the current work, shock tubes with arbitrary values of these parameters are considered over the complete range of Ms (the shock Mach number)

Non-Euclidean Triangle Centers

Non-Euclidean triangle centers can be described using homogeneous coordinates that are proportional to the generalized sines of the directed distances of a given center from the edges of the reference triangle. Identical homogeneous coordinates of a specific triangle center may be used for all spaces of uniform Gaussian curvature. We also define the median point for a set of points in non-Euclidean space and a planar center of rotation for a set of points in a non-Euclidean plane.Comment: 29 pages, 12 figures; added calculations of planar center of rotation for edges and interior of an isosceles triangl

A Dwarf Form of \u3ci\u3eEuptoieta Claudia\u3c/i\u3e (Lepidoptera: Nymphalidae)

During a collecting vacation in August, 1970, I captured several specimens of Euptoieta claudia (Cramer). After spreading the catch, the interesting gradation shown in the accompanying photograph was noted. Figure 1 shows a wing span range from 1 318\u27\u27 \u27to 2

Helping Our Students Reach Their Full Potential: The Insidious Consequences of Stereotype Threat

A psychological phenomenon may be a significant cause of academic underachievement by minorities in law school. This phenomenon, called stereotype threat, occurs as a result of the fear of confirming a negative group stereotype (such as African-Americans are not as intelligent as Whites). When subject to this threat — as a consequence of being confronted with environmental or explicit triggers — people do worse in academic settings than they otherwise are capable of doing. In this article, I explore the implications of the research on stereotype threat for law schools and make several recommendations to deal with the threat. There are natural implications for law school admissions, of course. If a portion of our applicant pool is affected by stereotype threat, then we cannot trust the accuracy of the metrics we typically use in law school admissions, i.e., prior academic performance and LSAT scores of law school applicants. Indeed, those credentials actually may under-evaluate the academic potential of these applicants, who are often minority students. This should cause law schools to reevaluate their admissions policies. After students are admitted, law school provides fertile ground within which stereotype threat can flourish. This, of course, means that the performance of minorities in law school — in class, on exams, and in other areas — is likely to be diminished, such that many minorities will not perform up to their academic capacity. And, obviously, we would expect this same dynamic to play out on the bar exam. Law schools can address stereotype threat at each of these levels, and they should do so. This article lays out a framework for understanding and dealing with the threat

LDR structural experiment definition

A system study to develop the definition of a structural flight experiment for a large precision segmented reflector on the Space Station was accomplished by the Boeing Aerospace Company for NASA's Langley Research Center. The objective of the study was to use a Large Deployable Reflector (LDR) baseline configuration as the basis for focusing an experiment definition, so that the resulting accommodation requirements and interface constraints could be used as part of the mission requirements data base for Space Station. The primary objectives of the first experiment are to construct the primary mirror support truss and to determine its structural and thermal characteristics. Addition of an optical bench, thermal shield and primary mirror segments, and alignment of the optical components, would occur on a second experiment. The structure would then be moved to the payload point system for pointing, optical control, and scientific optical measurement for a third experiment. Experiment 1 will deploy the primary support truss while it is attached to the instrument module structure. The ability to adjust the mirror attachment points and to attach several dummy primary mirror segments with a robotic system will also be demonstrated. Experiment 2 will be achieved by adding new components and equipment to experiment one. Experiment 3 will demonstrate advanced control strategies, active adjustment of the primary mirror alignment, and technologies associated with optical sensing