Pastoral resources and their management in the north-eastern goldfields, Western Australia

This report commences with a brief section in which rangeland survey information is put into a pastoral management context. It then describes the environment in terms of types of rangeland and climate. Types of rangeland are described in terms of pasture types, land systems and land types. A pasture type is a kind of land at a plant community or landform scale. It is what is seen out of the window of a vehicle and what monitoring sites are located on. A land system can be seen as a pattern of pasture types in a characteristic position in the landscape. Similar land systems are grouped into land types - these may be easier to deal with on a station plan if there are many land systems present

Improvements of organic aerosol representations and their effects in large-scale atmospheric models

Organics dominate the composition of the atmospheric aerosol, especially in the fine mode, influencing some of its characteristics such as the hygroscopicity, which is of climatic relevance for the Earth system. This study targets an improvement in the description of organic aerosols suitable for large-scale modelling, making use of recent developments based on laboratory and field measurements. In addition to the organic mass and particle number distribution, the proposed method keeps track of the oxidation state of the aerosol based on the OH exposure time, describing some of its chemical characteristics. This study presents the application of the method in a global chemistry climate model, investigates the sensitivity to process formulations and emission assignments, provides a comparison with observations and analyses the climate impact. <br></br> Even though the organic aerosol mass distribution is hardly affected by the new formulation, it shows impacts (regionally of the order of 10 % to 20 %) on parameters directly influencing climate via the direct and indirect aerosol effects. Furthermore, the global distribution of the organic O:C ratio is analysed in detail, leading to different regimes in the oxidation state: low O:C ratios over the tropical continents due to small OH concentrations caused by OH depletion in chemical reactions, and enhanced oxidation states over the tropical oceans based on less OH scavengers and at high altitudes due to longer atmospheric residence time. Due to the relation between O:C ratio and the aerosol hygroscopicity the ageing results in a more physically and chemically consistent description of aerosol water uptake by the organic aerosol. In comparison with observations reasonable agreement for the O:C ratio within the limits of a global model of the simulations is achieved

A key to the species of bluebushes (Maireana species) of the arid southern shrublands of Western Australia

This key has been produced to make identification of Maireana species (the bluebushes) easier in the arid shrublands region of Western Australia. It attempts to use everyday terms rather than technical botanical terms wherever possible and includes an illustrated diagram for ease of identification. A flow diagram - as opposed to traditional botanical keys - allows for visual tracking of steps taken in the key and hence makes it easier to backtrack if the final identified species seems incorrect.Fruit chacters alluded to at various steps in the key are also presented, and drawings of each species fruits are also included to provide a quick check of final identifications

Preliminary results on performance testing of a turbocharged rotary combustion engine

The performance of a turbocharged rotary engine at power levels above 75 kW (100 hp) was studied. A twin rotor turbocharged Mazda engine was tested at speeds of 3000 to 6000 rpm and boost pressures to 7 psi. The NASA developed combustion diagnostic instrumentation was used to quantify indicated and pumping mean effect pressures, peak pressure, and face to face variability on a cycle by cycle basis. Results of this testing showed that a 5900 rpm a 36 percent increase in power was obtained by operating the engine in the turbocharged configuration. When operating with lean carburetor jets at 105 hp (78.3 kW) and 4000 rpm, a brake specific fuel consumption of 0.45 lbm/lb-hr was measured

Are there brown dwarfs in globular clusters?

We present an analytical method for constraining the substellar initial mass function in globular clusters, based on the observed frequency of transit events. Globular clusters typically have very high stellar densities where close encounters are relatively common, and thus tidal capture can occur to form close binary systems. Encounters between main sequence stars and lower-mass objects can result in tidal capture if the mass ratio is > 0.01. If brown dwarfs exist in significant numbers, they too will be found in close binaries, and some fraction of their number should be revealed as they transit their stellar companions. We calculate the rate of tidal capture of brown dwarfs in both segregated and unsegregated clusters, and find that the tidal capture is more likely to occur over an initial relaxation time before equipartition occurs. The lack of any such transits in recent HST monitoring of 47 Tuc implies an upper limit on the frequency of brown dwarfs (< 15 % relative to stars) which is significantly below that measured in the galactic field and young clusters.Comment: MNRAS in pres

The evolution of a warped disc around a Kerr black hole

We consider the evolution of a warped disc around a Kerr black hole, under conditions such that the warp propagates in a wavelike manner. This occurs when the dimensionless effective viscosity, alpha, that damps the warp is less than the characteristic angular semi-thickness, H/R, of the disc. We adopt linearized equations that are valid for warps of sufficiently small amplitude in a Newtonian disc, but also account for the apsidal and nodal precession that occur in the Kerr metric. Through analytical and time-dependent studies, we confirm the results of Demianski & Ivanov, and of Ivanov & Illarionov, that such a disc takes on a characteristic warped shape. The inner part of the disc is not necessarily aligned with the equator of the hole, even in the presence of dissipation. We draw attention to the fact that this might have important implications for the directionality of jets emanating from discs around rotating black holes.Comment: 8 pages, 6 figures, to be published in MNRA

The Formation of Molecular Clouds

In a recent paper, Elmegreen (2000) has made a cogent case, from an observational point of view, that the lifetimes of molecular clouds are comparable to their dynamical timescales. If so, this has important implications for the mechanisms by which molecular clouds form. In particular we consider the hypothesis that molecular clouds may form not by {\it in situ} cooling of atomic gas, but rather by the agglomeration of the dense phase of the interstellar medium (ISM), much, if not most, of which is already in molecular form.Comment: 6 pages, no figures, accepted on 20 June 2001 for publication in MNRA