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The optical and semiconductor properties of the materials used in the design and manufacture of infrared interference filters play a vital role in defining the spectral performance achievable from a multilayer filter design. This thesis examines the theoretical basis of the behaviour of absorptive and dispersive mechanisms in optical materials and derives methods of determining values for their complex optical constants. By applying these properties to the multilayer filter design, a predictive model for the filter performance has been constructed to determine if a chosen design can achieve the specified spectral performance requirements, prior to manufacture. Examples are given demonstrating the convergence of prediction with practice. This predictive model approach has then been expanded to develop a method for determining the spectral design requirements for the individual filters and coatings integrated into an atmospheric radiometer instrument. This process uses an integrated systems approach, by which the characteristics of all the contributing elements provide a predicted spectral model of the instrument. By then applying reverse synthesis to this model, the particular spectral requirements of the individual filters can be determined. Examples are given of particular spectral design requirements for filters derived using this method. The effects of the space environment on the spectral and physical properties of infrared filters and materials is also presented. This includes a description of the radiation environments to which filters are subjected in low Earth orbit. A quantitative analysis of the effects of this environment on the spectral characteristics of exposed filters and materials is made, together with an assessment of the physical degradation mechanisms that affect filter performance.

Currently many airborne platforms (missiles, targets, and projectiles) contain multiple instrumentation systems to cover the functions of GPS and either telemetry, beacon tracking and/or flight termination. Most of these platforms are not very large, so mounting of various antennas to support these functions are physically close to each other. As a result, unwanted interference (in the form of RF coupling between them) is unavoidable. This paper will discuss the design considerations involved to minimize this interference as well as some lessons learned with its implementation.

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Absorber lined chambers (ALC's) or anechoic type enclosures operated under degraded conditions are introduced. Results of measurements inside scaled model ALC's are reported to demonstrate the feasibility of their use as environment simulators for electromagnetic susceptibility (E.M.S.) measurements over an extremely wide frequency range. The hardware and software of the automated microprocessor based facility developed for the measurement of amplitude and phase of e.m. fields in a volume of space, are described. / A geometrical optic (GO) technique and an 'idealized' material model to predict ALC fields is developed. Computed results are presented for a range of cases including some whose measurement would not be practicable. Using measured and computed data, criteria and guidelines for economic ALC design are established. / An experimental investigation of near-region scattering by various absorbers was carried out to seek the possibility of improving the material model with the objective of improving field prediction using the geometrical theory of diffraction (GTD).

RNA interference (RNAi) is a gene silencing mechanism induced by double-stranded RNA (dsRNA). RNAi has been used extensively to create loss-of-function mutants in many species to identify the functions of genes, but it also has the potential to be used as a species-specific pesticide if the dsRNA can silence essential genes in pests. The mosquito Aedes aegypti is a vector of numerous viruses including Dengue and West Nile virus, and is frequently controlled by chemical insecticides. With growing concerns about the extensive use of broad-spectrum pesticides, new control methods are eagerly sought. In this study, I examined the efficacy of feeding pesticidal dsRNAs to mosquito larvae. A dose-dependent RNAi response and mortality was observed when larvae were fed dsRNA targeting several different genes. Unlike RNAi in the related dipteran Drosophila melanogaster, RNAi in A. aegypti also appeared to be systemic, spreading beyond the gut to other tissues. A degree of species-specificity was also observed, as dsRNA specific to the D. melanogaster β-tubulin gene killed D. melanogaster larvae but did not kill mosquito larvae. RNAi was also used to determine the function of a newly-identified A. aegypti cytochrome P450 (CYP) gene, Aacyp. This gene showed male-biased expression in the mosquitoes, and was expressed primarily in the male abdomen and/or thorax, but unlike some other insect male-biased CYPs, Aacyp was not highly expressed in the reproductive structures. While dsRNA injections successfully knocked down expression of Aacyp, no discernable change in reproductive or male-specific behaviours were noted. Nevertheless, RNAi is still considered a highly versatile tool for both gene function studies and has promising potential to be developed into a novel class of pesticides.

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The release from proactive interference (PI) is a well-studied phenomenon, but its cause is elusive. When a release in PI is caused by changes in the content of to-be-remembered items, the more accurate retrieval is likely a result of changes in context (Watkins & Watkins, 1975). However, changes in context do not readily explain the cause of PI release resulting from a temporal delay. Instead, it could be that during the delay subjects disengage from intrusive information from previous trials. The ability to disengage from no-longer-relevant information is related to fluid intelligence (Gf). I predicted that this ability to disengage, as defined by fluid intelligence, is the driving factor of the time-based release from PI. In order to test this prediction, I administered a free recall task to individuals of high and low Gf. The time between the last two lists was lengthened to cause release. The time manipulation did not cause a release from PI; essentially, this result represents a failure to replicate. Limitations of the study and potential methodological issues are discussed.