The Murchison Widefield Array is a dipole-based aperture array synthesis telescope designed to operate in the 80-300 MHz frequency range. It is capable of a wide range of science investigations but is initially focused on three key science projects: detection and characterization of three-dimensional brightness temperature fluctuations in the 21 cm line of neutral hydrogen during the epoch of reionization (EoR) at redshifts from six to ten; solar imaging and remote sensing of the inner heliosphere via propagation effects on signals from distant background sources; and high-sensitivity exploration of the variable radio sky. The array design features 8192 dual-polarization broadband active dipoles, arranged into 512 ldquotilesrdquo comprising 16 dipoles each. The tiles are quasi-randomly distributed over an aperture 1.5 km in diameter, with a small number of outliers extending to 3 km. All tile-tile baselines are correlated in custom field-programmable gate array based hardware, yielding a Nyquist-sampled instantaneous monochromaticuvcoverage and unprecedented point spread function quality. The correlated data are calibrated in real time using novel position-dependent self-calibration algorithms. The array is located in the Murchison region of outback Western Australia. This region is characterized by extremely low population density and a superbly radio-quiet environment, allowing full exploitation of the instrumental capabilities.

Computational aspects of host-parasite phylogenies form part of a set of general associations between areas and organisms, hosts and parasites, and species and genes. The problem is not new and the commonalities of exploring vicariance biogeography (organisms tracking areas) and host-parasite co-speciation (parasites tracking hosts) have been recognised for some time. Methods for comparing host-parasite phylogenies are now well established and fall within two basic categories defined in terms of the way the data are interpreted in relation to the comparison of host-parasite phylogenies, so-called a posteriori, eg Brooks' Parsimony Analysis (BPA), or a priori, eg reconciled trees and other model-based methods, as implemented in the program TreeMap; the relative merits of the two philosophies inherent in these two approaches remain hotly debated. This paper reviews the computational methods currently available to analyse host-parasite relationships.