New broadband square-law detector

Compact device has wide dynamic range, accurate square-law response, good thermal stability, high-level dc output with immunity to ground-loop problems, ability to insert known time constants for radiometric applications, and fast response times compatible with computer systems

A new broadband square law detector

A broadband constant law detector was developed for precision power measurements, radio metric measurements, and other applications. It has a wide dynamic range and an accurate square law response. Other desirable characteristics, which are all included in a single compact unit, are: (1) high-level dc output with immunity to ground loop problems; (2) fast response times; (3) ability to insert known time constants; and (4) good thermal stability. The detector and its performance are described in detail. The detector can be operated in a programmable system with a ten-fold increase in accuracy. The use and performance of the detector in a noise-adding radiometer system is also discussed

The wheel has already been invented: Facilitating students' use of existing mechanics resources

Weve been teaching engineering mechanics to first year engineering students for a long time, yet at many engineering faculties around the world there are still significant failure rates⋯ Educators have tried many different approaches to address persistent high failure rates in first year engineering mechanics courses. These approaches often involve the development of new mechanics learning resources in a variety of styles depending on the perceived learning obstacle. As part of a project funded by the Australian Learning and Teaching Council on addressing student learning diversity in engineering mechanics we have developed a framework for reviewing these existing learning resources. This framework has been used to create a database of references to resources, categorising them by attributes such as topics covered and depth of coverage, suitable student learning styles, appropriate learner levels, copyright and accessibility issues. While it is anticipated that academics will use the database to complement their normal subject delivery, it has been developed with student users as the main target audience. Student focus groups have shown that independent study can be ineffective, particularly after hours when assistance is unavailable. The aim of this database is to encourage students to be proactive in improving the quality of their learning by assisting them to select learning resources best suited to their needs, in both content and style of delivery. In this paper we describe the elements of the framework used to review engineering mechanics resources, the resultant database of resources, and the planned evaluation of its effectiveness in improving learning outcomes. The authors intend to demonstrate use of the database at the conference. © 2010 Goldfinch & Gardner

Storage of correlated patterns in a perceptron

We calculate the storage capacity of a perceptron for correlated gaussian patterns. We find that the storage capacity $\alpha_c$ can be less than 2 if similar patterns are mapped onto different outputs and vice versa. As long as the patterns are in general position we obtain, in contrast to previous works, that $\alpha_c \geq 1$ in agreement with Cover's theorem. Numerical simulations confirm the results.Comment: 9 pages LaTeX ioplppt style, figures included using eps

Existence and stability of hole solutions to complex Ginzburg-Landau equations

We consider the existence and stability of the hole, or dark soliton, solution to a Ginzburg-Landau perturbation of the defocusing nonlinear Schroedinger equation (NLS), and to the nearly real complex Ginzburg-Landau equation (CGL). By using dynamical systems techniques, it is shown that the dark soliton can persist as either a regular perturbation or a singular perturbation of that which exists for the NLS. When considering the stability of the soliton, a major difficulty which must be overcome is that eigenvalues may bifurcate out of the continuous spectrum, i.e., an edge bifurcation may occur. Since the continuous spectrum for the NLS covers the imaginary axis, and since for the CGL it touches the origin, such a bifurcation may lead to an unstable wave. An additional important consideration is that an edge bifurcation can happen even if there are no eigenvalues embedded in the continuous spectrum. Building on and refining ideas first presented in Kapitula and Sandstede (Physica D, 1998) and Kapitula (SIAM J. Math. Anal., 1999), we show that when the wave persists as a regular perturbation, at most three eigenvalues will bifurcate out of the continuous spectrum. Furthermore, we precisely track these bifurcating eigenvalues, and thus are able to give conditions for which the perturbed wave will be stable. For the NLS the results are an improvement and refinement of previous work, while the results for the CGL are new. The techniques presented are very general and are therefore applicable to a much larger class of problems than those considered here.Comment: 41 pages, 4 figures, submitte

Ageism in the third age

In the developed world, later life has brought more opportunities to contribute to society and pursue personal goals outside the role of paid work, combined with less stigma and greater recognition of the worth of older people. These values do not necessarily extend to the “oldest old” where some people in the fourth age (people 80 years old and over) continue to face increasing stigma and societal stereotypes from those in the third age (people 60–79 years old). Ageism between these two cohorts is rarely discussed in the literature. Potential ageism involves stereotypical perceptions of the oldest old and may prove detrimental to those transitioning from the third to the fourth age if a resultant resistance to maintain their engagement and independence into older age occurs. This chapter explores the subtleties of these inter-cohort ageist discourses particularly from a health and social care perspective and considers the implications for transitions of older people between the third and fourth age. It addresses the challenges and adjustments needed to ensure continuing and inclusive engagement in society, in order to support independence to grow old without the fear of discrimination

Galaxy Counts, Sizes, Colours and Redshifts in the Hubble Deep Field

We compare the galaxy evolution models of Bruzual & Charlot (1993) with the faint galaxy count, size and colour data from the Hubble and Herschel Deep Fields (Metcalfe et al 1996). For qo=0.05, we find that models where the SFR increases exponentially out to z>2 are consistent with all of the observational data. For qo=0.5, such models require an extra population of galaxies which are only seen at high redshift and then rapidly fade or disappear. We find that, whatever the cosmology, the redshift of the faint blue galaxies and hence the epoch of galaxy formation is likely to lie at z>2. We find no implied peak in the SFR at z=1 and we suggest that the reasons for this contradiction with the results of Madau et al (1996) include differences in faint galaxy photometry, in the treatment of spiral dust and in the local galaxy count normalisation.Comment: 8 pages, 5 eps figures, needs paspconf.st

Eucalypts of Western Australia

The series Trees of Western Australia, which appeared in The Journal of Agriculture of Western Australia, was commenced in 1952 by Charles Austin Gardner, Government Botanist and Curator of the Western Australian Herbarium from 1929 to1960. Until his death in 1970 Gardner published in the series 29 articles, dealing with 117 species of Eucalyptus, the last article appearing in 1966. The articles are of historical and scientific interest. They contain valuable original information on the phytogeography and taxonomy of over half of the Western Australian species of Eucalyptus, based largely on Gardner\u27s personal observations made in the course of his extensive travels in Western Australia. Each species is illustrated by his own diagnostic line drawings.https://researchlibrary.agric.wa.gov.au/bulletins/1215/thumbnail.jp