Application of distorted models in developing scaled structural models

In the design and development of dynamically similar structural models a distorted model of the panel is used. The panel thickness is made larger than that dictated by geometric scaling, and the mass of the panel is decreased by adding mass to the surface of the panel to counteract the additional stiffness obtained by the thickness increase

The Apollo 15 deployable boom anomaly

During the Apollo 15 mission, a boom with an attached mass spectrometer was required to retract periodically so that the instrument would not be in the field of view of other experiments. The boom did not fully retract on five of 12 occasions. Data analysis indicated that the boom probably retracted to within approximately 2.54 centimeters (1 inch) of full retraction. The pertinent boom-design details, the events in the mission related to the anomaly, a discussion of the inflight and postflight investigation of the problem, a discussion of the design changes to the boom mechanism as a result of the investigation, and subsequent flight performance are presented

Laser amplification in an inhomogeneous plasma

The propagation of an electromagnetic wave into an inhomogeneous plasma was studied. In a plasma with large density gradients a QTX mode propagating perpendicular to the magnetic field can encounter a resonance and a cutoff separated by a distance comparable to the incident wave length. In this region the wave is evanescent, and in general there will be a reflected and transmitted wave, and amplification will occur in the region near the resonance. The amplification is important for the study of nonlinear phenomena and for feedback stabilization applications

Learning Together: Using Action Research to Design Professional Development

After being part of a week-long math institute, both the principal and the Mathematics Specialist from an urban school district partnered to develop a professional development plan. It incorporated a Lesson Study Model that supported collaborative learning teams, focused on the instructional process, and incorporated reflection and feedback. Although the faculty had engaged in other forms of professional development, the lesson study process was seen as a powerful vehicle that invited a level of coaching and cross-collaboration. This article focuses on the shared viewpoints of the principal and the Mathematics Specialist who worked together to build a mechanism for professional learning for improved mathematical proficiency and understanding

Acid-base homeostasis in the human system

Acid-base regulation is a cooperative phenomena in vivo with body fluids, extracellular and intracellular buffers, lungs, and kidneys all playing important roles. The present account is much too brief to be considered a review of present knowledge of these regulatory systems, and should be viewed, instead, as a guide to the elements necessary to construct a simple model of the mutual interactions of the acid-base regulatory systems of the body

Ground truth applications to orbit refinements

A weighted least-squares recursive estimator program is reported for simulating spacecraft orbital position by analyzing earth and sun sensor data. The program uses constant time adjustment for a set of ephemeris data to eliminate intrack error and to improve attitude determination accuracy

Improved Limits on B0B^{0} decays to invisible (+γ)(+\gamma) final states

We establish improved upper limits on branching fractions for B0 decays to final States 10 where the decay products are purely invisible (i.e., no observable final state particles) and for final states where the only visible product is a photon. Within the Standard Model, these decays have branching fractions that are below the current experimental sensitivity, but various models of physics beyond the Standard Model predict significant contributions for these channels. Using 471 million BB pairs collected at the Y(4S) resonance by the BABAR experiment at the PEP-II e+e- storage ring at the SLAC National Accelerator Laboratory, we establish upper limits at the 90% confidence level of 2.4x10^-5 for the branching fraction of B0-->Invisible and 1.7x10^-5 for the branching fraction of B0-->Invisible+gammaComment: 8 pages, 3 postscript figures, submitted to Phys. Rev. D (Rapid Communications

Web document summarisation: a task-oriented evaluation

We present a query-biased summarisation interface for Web searching. The summarisation system has been specifically developed to act as a component in existing Web search interfaces. The summaries allow the user to more effectively assess the content of Web pages. We also present an experimental investigation of this approach. Our experimental results shows the system appears to be more useful and effective in helping users gauge document relevance than the traditional ranked titles/abstracts approach