Performance of the square root information filter for navigation of the Mariner 10 spacecraft

The use is described of a sequential least squares filter in the orbit determination for the Mariner Venus-Mercury (Mariner 10) spacecraft. The orbit determination strategy outlining the use of both the sequential filter and a conventional batch filter is given. Highlighted are the mission events from launch to the first Mercury encounter with emphasis on the sequential filter performance. Advantages to the mission derived from the sequential filter are pointed out

On the choice of parameters in solar structure inversion

The observed solar p-mode frequencies provide a powerful diagnostic of the internal structure of the Sun and permit us to test in considerable detail the physics used in the theory of stellar structure. Amongst the most commonly used techniques for inverting such helioseismic data are two implementations of the optimally localized averages (OLA) method, namely the Subtractive Optimally Localized Averages (SOLA) and Multiplicative Optimally Localized Averages (MOLA). Both are controlled by a number of parameters, the proper choice of which is very important for a reliable inference of the solar internal structure. Here we make a detailed analysis of the influence of each parameter on the solution and indicate how to arrive at an optimal set of parameters for a given data set.Comment: 14 pages, 15 figures. Accepted for publication on MNRA

Book Review

Review of: MARY R. ENGLISH, SITING LOW-LEVEL RADIOACTIVE WASTE DISPOSAL FACILITIES: THE PUBLIC POLICY DILEMMA. (Quorum Books 1992) [278 pp.], Appendices, index, introduction, references. LC-91-42774; ISBN 0-89930-560-1. [$49.95 cloth. One Madison Avenue, New York NY 10010.

Information and Communications Technology in Chronic Disease Care: Why is Adoption So Slow and Is Slower Better?

Unlike the widespread adoption of information and communications technology (ICT) in much of the economy, adoption of ICT in clinical care is limited. We examine how a number of not previously emphasized features of the health care and ICT markets interact and exacerbate each other to create barriers for adoption. We also examine how standards can address these barriers and the key issues to consider before investing in ICT. We conclude that the ICT market exhibits a number of unique features that may delay or completely prevent adoption, including low product differentiation, high switching costs, and lack of technical compatibility. These barriers are compounded by the many interlinked markets in health care, which substantially blunt the use of market forces to influence adoption. Patient heterogeneity also exacerbates the barriers by wide variation in needs and ability for using ICT, by high demands for interoperability, and by higher replacement costs. Technical standards are critical for ensuring optimal use of the technology. Careful consideration of the socially optimal time to invest is needed. The value of waiting in health care is likely to be so much greater than in other sectors because the costs of adopting the wrong type of ICT are so much higher.