The sparrow invasion of 1962

During late 1962 and early 1963, a report that sparrows were at large in the metropolitan area close to Perth drew intense public interest. This article gives some facts about the reported sightings

Spin dynamics in the antiferromagnetic phase for electron-doped cuprate superconductors

Based on the $t$-$t'$-$t''$-$J$ model we have calculated the dynamical spin susceptibilities in the antiferromagnetic (AF) phase for electron-doped cuprates, by use of the slave-boson mean-field theory and random phase approximation. Various results for the susceptibilities versus energy and momentum have been shown at different dopings. At low energy, except the collective spin-wave mode around $(\pi,\pi)$ and 0, we have primarily observed that new resonance peaks will appear around $(0.3\pi,0.7\pi)$ and equivalent points with increasing doping, which are due to the particle-hole excitations between the two AF bands. The peaks are pronounced in the transverse susceptibility but not in the longitudinal one. These features are predicted for neutron scattering measurements.Comment: 5 pages, 3 figures, published version with minor change

Wildlife hazards from 1080 baiting

ONE-SHOT oat baiting with sodium fluoroacetate (1080) is a relatively safe method of trail baiting rabbits. The hazard to wildlife is small and every effort is made to further reduce the hazard by selective application of the poison

Unifying the Phase Diagrams of the Magnetic and Transport Properties of La_(2-x)Sr_xCuO_4, 0 < x < 0.05

An extensive experimental and theoretical effort has led to a largely complete mapping of the magnetic phase diagram of La_(2-x)Sr_xCuO_4, and a microscopic model of the spin textures produced in the x < 0.05 regime has been shown to be in agreement with this phase diagram. Here we use this same model to derive a theory of the impurity-dominated, low temperature transport. Then, we present an analysis of previously published data for two samples: x = 0.002 data from Chen et. al., and x = 0.04 data from Keimer et. al. We show that the transport mechanisms in the two systems are the same, even though they are on opposite sides of the observed insulator-to-metal transition. Our model of impurity effects on the impurity band conduction, variable-range hopping conduction, and coulomb gap conduction, is similar to that used to describe doped semiconductors. However, for La_(2-x)Sr_xCuO_4 we find that in addition to impurity-generated disorder effects, strong correlations are important and must be treated on a equal level with disorder. On the basis of this work we propose a phase diagram that is consistent with available magnetic and transport experiments, and which connects the undoped parent compound with the lowest x value for which La_(2-x)Sr_xCuO_4 is found to be superconducting, x about 0.06.Comment: 7 pages revtex with one .ps figur

Rabbit control with 1080

The lower South-West areas have for some time past been regarded as perhaps the most difficult areas in Western Australia from the point of view of rabbit control. The farmer here has to contend with several factors, peculiar to this area, which make his work more difficult. Such obstacles as bracken fern, falling timber, good burrowing soil and a long breeding season combined with small holdings, lack of rabbit control experience, partial use of the cleared areas (tobacco and potato growers) and a low income potential, have rendered the task of rabbit control exceedingly difficult for the average farmer, especially in the Manjimup-Pemberton areas

Magnetic susceptibility of a CuO2 plane in the La2CuO4 system: I. RPA treatment of the Dzyaloshinskii-Moriya Interactions

Motivated by recent experiments on undoped La2CuO4, which found pronounced temperature-dependent anisotropies in the low-field magnetic susceptibility, we have investigated a two-dimensional square lattice of S=1/2 spins that interact via Heisenberg exchange plus the symmetric and anti-symmetric Dzyaloshinskii-Moriya anisotropies. We describe the transition to a state with long-ranged order, and find the spin-wave excitations, with a mean-field theory, linear spin-wave analysis, and using Tyablikov's RPA decoupling scheme. We find the different components of the susceptibility within all of these approximations, both below and above the N'eel temperature, and obtain evidence of strong quantum fluctuations and spin-wave interactions in a broad temperature region near the transition.Comment: 20 pages, 2 column format, 22 figure

The new approach to rabbit poisoning 1080 and improved methods

The rabbit in Australia has only a relatively short history*, but during that period, of 168 years, has probably done more harm to this country than any other pest. In Western Australia, as in some of the other States, investigations directed towards the improvement of control methods—particularly poisoning—have been intensified over recent years. Although it is recognised that no single method could accomplish eradication or give completely satisfactory control, it is also evident that the improvement of poisoning methods could help greatly. Some of our investigations have been aimed at improving techniques in poisoning procedure and also in finding better poisons. One of the new poisons, 1080 (sodium fluoroacetate) has proved very effective

Topological Defects and the Spin Glass Phase of Cuprates

We propose that the spin glass phase of cuprates is due to the proliferation of topological defects of a spiral distortion of the antiferromagnet order. Our theory explains straightforwardly the simultaneous existence of short range incommensurate magnetic correlations and complete a-b symmetry breaking in this phase. We show via a renormalization group calculation that the collinear O(3)/O(2) symmetry is unstable towards the formation of local non-collinear correlations. A critical disorder strength is identified beyond which topological defects proliferate already at zero temperature.Comment: 7 pages, 2 figures. Final version with some changes and one replaced figur