Military Radio Communications Research in Australia

An overview of recent research by the Australian Defence Science and Technology Organisation in the field of military radio communications is presented. A philosophy for improving digital radio system performance over complex, variable channels is outlined. A key breakthrough, called PDF-directed adaptive radio, which can provide substantially greater throughput over HF channels whilst minimising bit-error rate and delay, is described. Simulation results for fast adaptive Schemes applied to both serial-tone and parallel-tone HF modems are presented and shown to significantly out-perform fixed rate modems and modems employing hybrid automatic-repeat-request schemes. A new detector scheme is discussed which has superior performance to conventional detectors for digital traffic in the presence of inter-symbol interference and impulsive noise

A systematic review of high quality randomized controlled trials investigating motor skill programmes for children with developmental coordination disorder

Objective: To identify effective motor training interventions for children with developmental coordination disorder from research graded as high quality (using objective criteria) for the purpose of informing evidence-based clinical practice. Data sources: We followed the guidance for conducting systematic reviews issued by the Centre for Reviews and Dissemination. Six OvidSP electronic databases (AMED, All EBM reviews (including Cochrane), Embase, Ovid MEDLINE, PsychARTICLES Full Text, PsycINFO) were searched systematically. We aimed to retain only randomized control trials and systematic reviews of randomized control trials, defined as the highest level of evidence by the Oxford Centre for Evidence-Based Medicine. We searched reference lists of retained articles to identify further appropriate articles. Review methods: Two reviewers critically appraised and categorized articles by effect size (including confidence intervals), inclusion of power calculations and quality using the Physiotherapy Evidence Database (PEDro) scale. Only studies scoring seven or more on the PEDro scale (classed by the PEDro as high reliability) were retained. Results: No systematic reviews met our criteria for inclusion from 846 articles yielded by the systematic search. Nine randomized control trials investigating 15 interventions to improve motor skills met our inclusion criteria for 'high quality'. Nevertheless, not all included studies were adequately powered for determining an effect. Conclusion: Large effect sizes associated with 95 % confidence intervals suggest that 'Neuromotor Task Training', 'Task-oriented Motor Training' and 'Motor Imagery + Task Practice Training' are the most effective reported interventions for improving motor skills in children with developmental coordination disorder.</p

Explosive dome eruptions modulated by periodic gas-driven inflation

Volcan Santiaguito (Guatemala) "breathes" with extraordinary regularity as the edifice's conduit system accumulates free gas, which periodically vents to the atmosphere. Periodic pressurization controls explosion timing, which nearly always occurs at peak inflation, as detected with tiltmeters. Tilt cycles in January 2012 reveal regular 26 ± 6 min inflation/deflation cycles corresponding to at least ~101 kg/s of gas fluxing the system. Very long period (VLP) earthquakes presage explosions and occur during cycles when inflation rates are most rapid. VLPs locate ~300 m below the vent and indicate mobilization of volatiles, which ascend at ~50 m/s. Rapid gas ascent feeds pyroclast-laden eruptions lasting several minutes and rising to ~1 km. VLPs are not observed during less rapid inflation episodes; instead, gas vents passively through the conduit producing no infrasound and no explosion. These observations intimate that steady gas exsolution and accumulation in shallow reservoirs may drive inflation cycles at open-vent silicic volcanoes. Key Points Regular 26 min inflation/deflation cycles are observed at silicic volcanoInflation rates control whether volcano explodes or passively degassesLocation of gas reservoir and flux of gas through the volcano are quantifie

Noncolliding Squared Bessel Processes

We consider a particle system of the squared Bessel processes with index $\nu > -1$ conditioned never to collide with each other, in which if $-1 < \nu < 0$ the origin is assumed to be reflecting. When the number of particles is finite, we prove for any fixed initial configuration that this noncolliding diffusion process is determinantal in the sense that any multitime correlation function is given by a determinant with a continuous kernel called the correlation kernel. When the number of particles is infinite, we give sufficient conditions for initial configurations so that the system is well defined. There the process with an infinite number of particles is determinantal and the correlation kernel is expressed using an entire function represented by the Weierstrass canonical product, whose zeros on the positive part of the real axis are given by the particle-positions in the initial configuration. From the class of infinite-particle initial configurations satisfying our conditions, we report one example in detail, which is a fixed configuration such that every point of the square of positive zero of the Bessel function $J_{\nu}$ is occupied by one particle. The process starting from this initial configuration shows a relaxation phenomenon converging to the stationary process, which is determinantal with the extended Bessel kernel, in the long-term limit.Comment: v3: LaTeX2e, 26 pages, no figure, corrections made for publication in J. Stat. Phy

Jurassic stratigraphy of the Faroe-Shetland region : implications for the evolution of the proto-NE Atlantic margin

This report is the result of a joint study by the British Geological Survey (BGS) and Jarðfeingi (the Faroese Earth and Energy Directorate) on behalf of the Faroe-Shetland Consortium (FSC) and presents a regional analysis of Jurassic stratigraphy of the Faroe-Shetland region and the implications for the evolution of the proto-NE Atlantic margin. This report integrates the main conclusions of the various component studies that comprise the ‘Jurassic Project’. Readers are directed to the individual, detailed reports for further background information, a discussion of methodology and a fuller discussion of the conclusions. The detailed reports cover the following subjects: seismic interpretation, structure and thickness (Quinn 2018), sedimentology (Dodd, 2018) and palynology (Riding, 2018a-i and Thomas, 2018a-j)

A dimensionally continued Poisson summation formula

We generalize the standard Poisson summation formula for lattices so that it operates on the level of theta series, allowing us to introduce noninteger dimension parameters (using the dimensionally continued Fourier transform). When combined with one of the proofs of the Jacobi imaginary transformation of theta functions that does not use the Poisson summation formula, our proof of this generalized Poisson summation formula also provides a new proof of the standard Poisson summation formula for dimensions greater than 2 (with appropriate hypotheses on the function being summed). In general, our methods work to establish the (Voronoi) summation formulae associated with functions satisfying (modular) transformations of the Jacobi imaginary type by means of a density argument (as opposed to the usual Mellin transform approach). In particular, we construct a family of generalized theta series from Jacobi theta functions from which these summation formulae can be obtained. This family contains several families of modular forms, but is significantly more general than any of them. Our result also relaxes several of the hypotheses in the standard statements of these summation formulae. The density result we prove for Gaussians in the Schwartz space may be of independent interest.Comment: 12 pages, version accepted by JFAA, with various additions and improvement

Maturation, Peer Context, and Indigenous Girls\u27 Early-Onset Substance Use

This paper examines a biosocial model of the impact of puberty on Indigenous girls\u27 early-onset substance use by considering the potential mediating role of peer context (i.e. mixed-sex peer groups and substance use prototypes) on the puberty and substance use relationship. Data include responses from 360 girls of a common Indigenous cultural group residing on reservations/reserves in the upper Midwest and Canada. Results of structural equation modeling revealed that the statistically significant relationship between girls\u27 pubertal development and early-onset substance use was mediated by both mixed-sex/romantic peer groups and favorable social definitions of substance use. Implications for substance use prevention work include addressing the multiple and overlapping effects of peer influence from culturally-relevant perspectives

Inductive Proof Outlines for Monitors in Java

Abstract. The research concerning Java’s semantics and proof theory has mainly focussed on various aspects of sequential sub-languages. Java, however, integrates features of a class-based object-oriented language with the notion of multi-threading, where multiple threads can concurrently execute and exchange information via shared instance variables. Furthermore, each object can act as a monitor to assure mutual exclusion or to coordinate between threads. In this paper we present a sound and relatively complete assertional proof system for Java’s monitor concept, which generates verification conditions for a concurrent sublanguage JavaMT of Java. This work extends previous results by incorporating Java’s monitor methods

Slot Coating Minimum Film Thickness in Air and in Rarefied Helium

YesThis study assesses experimentally the role of gas viscosity in controlling the minimum film thickness in slot coating in both the slot over roll and tensioned web modes. The minimum film thickness here is defined with respect to the onset of air entrainment rather than rivulets, the reason being that rivulets are an extreme form of instabilities occurring at much higher speeds. The gas viscosity effects are simulated experimentally by encasing the coaters in a sealed gas chamber in which various gases can be admitted. An appropriate choice of two gases was used to compare performances: air at atmospheric pressure and helium at sub-ambient pressure (25mbar), which we establish has a significantly lower “thin film” viscosity than atmospheric air. A capacitance sensor was used to continuously measure the film thickness on the web, which was ramped up in speed at a fixed acceleration whilst visualizations of the film stability were recorded through a viewing port in the chamber. The data collected show clearly that by coating in rarefied helium rather that atmospheric air we can reduce the minimum film thickness or air/gas entrainment low-flow limit. We attribute this widening of the stable coating window to the enhancement of dynamic wetting that results when the thin film gas viscosity is reduced. These results have evident practical significance for slot coating, the coating method of choice in many new technological applications, but it is their fundamental merit which is new and one that should be followed with further data and theoretical underpinning

Accuracy and Stability of Computing High-Order Derivatives of Analytic Functions by Cauchy Integrals

High-order derivatives of analytic functions are expressible as Cauchy integrals over circular contours, which can very effectively be approximated, e.g., by trapezoidal sums. Whereas analytically each radius r up to the radius of convergence is equal, numerical stability strongly depends on r. We give a comprehensive study of this effect; in particular we show that there is a unique radius that minimizes the loss of accuracy caused by round-off errors. For large classes of functions, though not for all, this radius actually gives about full accuracy; a remarkable fact that we explain by the theory of Hardy spaces, by the Wiman-Valiron and Levin-Pfluger theory of entire functions, and by the saddle-point method of asymptotic analysis. Many examples and non-trivial applications are discussed in detail.Comment: Version 4 has some references and a discussion of other quadrature rules added; 57 pages, 7 figures, 6 tables; to appear in Found. Comput. Mat