Performance of the adaptive sidelobe blanker detection algorithm inhomogeneous environments

The adaptive sidelobe blanker (ASB) algorithm is a two-stage detector consisting of a first stage adaptive matched filter (AMF) detector followed by a second-stage detector called the adaptive coherence (or cosine) estimator (ACE). Only those data test cells that survive both detection thresholdings are declared signal (target) bearing. We provide exact novel closed-form expressions for the resulting probability of detection (PD) and false alarm (PFA) for the ASB algorithm and demonstrate that under homogeneous data conditions with no signal array response mismatch that (i) the ASB is a constant false alarm rate (CFAR) algorithm, (ii) the ASB has a higher or commensurate PD for a given PFA than both the AMF and the ACE, and (iii) the ASB has an overall performance that is commensurate with Kelly's (1986) benchmark generalized likelihood ratio test (GLRT). A compact statistical summary is derived providing distributions and dependencies among the GLRT, AMF, and the ACE decision statistics     

Stage distributions for five health behaviors in the United States and Australia

BACKGROUND: A key variable for the design of individual and public health interventions is the Stage of Change. The five stages of readiness to change are Precontemplation, Contemplation, Preparation, Action, and Maintenance. The distribution of individuals across the stages of change can provide a valuable tool for designing health interventions. METHODS: The pattern of distribution across the stages of change for five behavioral risk factors is presented from five independent surveys, two from the United States and three from Australia. The five risk factors are smoking, low fat diet, regular exercise, reducing stress, and losing weight. Identical single-item questionnaire items for staging health behaviors were used in all surveys. RESULTS: The stage distributions for the five risk factors were similar across the five independent samples. In general, the pattern of stage distributions was stable across health risk factors, gender, country, and sample. CONCLUSIONS: Single-item survey measures of stage of change that are readily applicable to population studies appear to provide important information about the population characteristics of readiness to change behavioral risk factors. The stability of these distributions suggests that interventions matched by stage may have broad applicability.     

"A lab of one's own". The Balfour Biological Laboratory for Women at Cambridge University, 1884-1914

The Balfour Biological Laboratory for Women was established at Cambridge University in 1884 to prepare the students of Newnham and Girton Colleges to sit the Natural Sciences Tripos, first opened to women in 1881. For thirty years, until its closure in 1914, the Balfour Laboratory served as the central conduit for biological instruction for the women of Cambridge, introducing them to the new program of experimental biology developed by the physiologist Michael Foster and the embryologist Francis Maitland Balfour. Directed by distinguished women graduates, the Balfour Laboratory became recognized as the leading center for women's biological instruction in Britain. Its significance, however, extends beyond its nominal status as a teaching laboratory. It provided university positions for able scientists who otherwise would not have been placed, offered advanced students the opportunity to engage in independent research, and, most important, formed the locus for the scientific subculture created by women at Cambridge to compensate for their exclusion from the social community of science. Drawing upon college and university archival records, this essay offers institutional, social, and biographical research that broadens our understanding of the experience of the first generation of women to pursue a higher education in the life sciences at one of the world's premier universities.     

Scattering by a dielectric cylinder of arbitrary cross section shape

The theory and equations are developed for the scattering pattern of a dielectric cylinder of arbitrary cross section shape. The harmonic incident wave is assumed to have its electric vector parallel with the axis of the cylinder, and the field intensities are assumed to be independent of distance along the axis. Solutions are readily obtained for inhomogeneous cylinders when the permittivity is independent of distance along the cylinder axis. Although other investigators have approximated the field within the dielectric body by the incident field, we treat the total field as an unknown function which is determined by solving a system of linear equations. In the case of the dielectric cylindrical shell of circular cross section, this technique yields results which agree accurately with the exact classical solution. Scattering patterns are also presented in graphical form for a dielectric shell of semicircular cross section, a thin homogeneous plane dielectric sheet of finite width, and an inhomogeneous plane sheet. The effects of surface-wave excitation and mutual interaction among the various portions of the dielectric shell are included automatically in this solutiom     

Ideal forming—II. Sheet forming with optimum deformation

A method is proposed for the design of ideal forming processes. The objective is to directly determine ideal configurations for both the initial and the intermediate stages that are required to form a specified final shape. At the start, it is assumed that formability of local material elements is optimum when they deform in minimum work paths. The ideal global process is then defined as the one having such local deformations optimally distributed in a final shape. Mathematical procedures for implementing these conditions are derived. Primary emphasis is placed upon forming of sheet (membrane) materials under plane-stress conditions, although many of the ideas are applicable to more general forming processes. Sample results illustrate optimum process parameters which the ideal forming theory can provide.