bluuebunny/crossref_metadata_2025 huggingface dataset:
A reference interaction site model approach to depletion forces induced by hard rodlike particles
Authors: González-Mozuelos P. , Méndez-Alcaraz J. M. , Castañeda-Priego R.
Published: December 2005

We study the effective interactions among large hard spherical colloidal particles induced by small hard rodlike particles and compare them with those induced by small hard spherical particles to highlight the specific effects due to the anisotropic shape of the former. This is done by determining the effective pair potentials within the framework of the reference interaction site model approach. The rodlike particles are modeled as N nonoverlapping spherical units arranged in a straight line, so that their total length is N times their transversal diameter. These results are compared against those obtained in the Asakura-Oosawa limit.
Comment on “Path-integral virial estimator based on the scaling of fluctuation coordinates: Application to quantum clusters with fourth-order propagators” [J. Chem. Phys.123, 104101 (2005)]
Authors: Predescu Cristian
Published: December 2005

The comment attempts to clarify what constitutes a safe use of the Feynman-Kac formula for the purpose of deriving estimators through formal differentiation of the density matrix.
Piezoelectric characterization of ejecta from shocked tin surfaces
Authors: Vogan W. S. , Anderson W. W. , Grover M. , Hammerberg J. E. , King N. S. P. , Lamoreaux S. K. , Macrum G. , Morley K. B. , Rigg P. A. , Stevens G. D. , Turley W. D. , Veeser L. R. , Buttler W. T.
Published: December 2005

Using piezoelectric diagnostics, we have measured densities and velocities of ejected particulate as well as “free-surface velocities” of bulk tin targets shock loaded with high explosive. The targets had finely grooved, machined finishes ranging from 10 to 250μin. Two types of piezoelectric sensor (“piezopins”), lithium niobate and lead zirconate titanate, were compared for durability and repeatability; in addition, some piezopins were “shielded” with foam and metal foil in order to mitigate premature failure of the pins in high ejecta regimes. These experiments address questions about ejecta production at a given shock pressure as a function of surface finish; piezopin results are compared with those from complementary diagnostics such as x-ray radiography and time-resolved optical transmission techniques. The mass ejection shows a marked dependence on groove characteristics and cannot be described by a groove defect theory alone.
Understanding glycine conformation through molecular orbitals
Authors: Falzon Chantal T. , Wang Feng
Published: December 2005

The four most stable Cs conformers of glycine have been investigated using a variety of quantum-mechanical methods based on Hartree-Fock theory, density-functional theory (B3LYP and statistical average of orbital potential), and electron propagation (OVGF) treatments. Information obtained from these models were analyzed in coordinate and momentum spaces using dual space analysis to provide insight based on orbitals into the bonding mechanisms of glycine conformers, which are generated by rotation of C–O(H) (II), C–C (III), and C–N (IV) bonds from the global minimum structure (I). Wave functions generated from the B3LYP/TZVP model revealed that each rotation produced a unique set of fingerprint orbitals that correspond to a specific group of outer valence orbitals, generally of a′ symmetry. Orbitals 14a′, 13a′, 12a′, and 11a′ are identified as the fingerprint orbitals for the C–O(H) (II) rotation, whereas fingerprint orbitals for the C–C (III) bond rotation are located as 16a′ [highest occupied molecular orbital (HOMO)], 15a′ [next highest molecular occupied molecular orbital (NHOMO)], 14a′, and 12a′ orbitals. Fingerprint orbitals for IV generated by the combined rotations around the C–C, C–O(H), and C–N bonds are found as 16a′, 15a′, 14a′, 13a′, and 11a′, as well as in orbitals 2a″ and 1a″. Orbital 14a′ is identified as the fingerprint orbital for all three conformational processes, as it is the only orbital in the outer valence region which is significantly affected by the conformational processes regardless rotation of which bond. Binding energies, molecular geometries, and other molecular properties such as dipole moments calculated based on the specified treatments agree well with available experimental measurements and with previous theoretical calculation.
Bond order bond polarizability model for fullerene cages and nanotubes
Authors: Hu Yun Hang , Ruckenstein Eli
Published: December 2005

It is still a challenge to accurately calculate the polarizabilities of large fullerene cages and nanotubes. In this paper, a simple bond order bond polarizability relationship for carbon was found, which allowed us to apply the bond polarizability model to any pentagon isolation rule (PIR) fullerene (cage or nanotube). Following this approach, the following simple equation, α=1.262n, was obtained relating the static dipole polarizability (α) of PIR fullerenes (cages or closed nanotubes) to their number (n) of carbon atoms. Furthermore, it was shown that the polarizabilities of C60 and C70, calculated on the basis of this model, are in excellent agreement with those obtained experimentally and by density-functional theory calculations.
Voltage-controlled tunneling anisotropic magnetoresistance of a ferromagnetic p++-(Ga,Mn)As∕n+-GaAs Zener-Esaki diode
Authors: Giraud R. , Gryglas M. , Thevenard L. , Lemaître A. , Faini G.
Published: December 2005

The large tunneling anisotropic magnetoresistance of a ferromagnetic p++-(Ga,Mn)As∕n+-GaAs Zener-Esaki diode is shown in a perpendicular magnetic field over a large temperature and voltage range. Under an applied bias, the tunnel junction transparency is modified, allowing one to continuously tune anisotropic transport properties between the tunneling and the ohmic regimes. Furthermore, an asymmetric bias dependence of the tunneling anisotropic magnetoresistance is also observed: A reverse bias highlights the full (Ga,Mn)As valence-band states contribution, whereas a forward bias only probes part of the density of states and reveals opposite contributions from two valence subbands.
Dielectric response of temperature-graded ferroelectric films
Authors: Cao Hai-Xia , Lo Veng Cheong , Li Zhen-Ya
Published: December 2005

The dielectric susceptibility and dielectric tunability of the temperature-graded BaTiO3 thin films are investigated by using a modified transverse Ising model, taking the four-spin interaction and quantum fluctuation into account. There is a broad and smooth peak of the dielectric susceptibility at low temperature except for the sharp dielectric peak corresponding to the phase-transition temperature, irrespective of the sign of the temperature gradient. This behavior is different from the homogeneous bulk materials. Although the temperature gradient reduces the dielectric susceptibility, the temperature stability of the dielectric susceptibility can be effectively improved between the two dielectric peaks. The quantum fluctuation not only can enhance the temperature stability of the dielectric susceptibility but also has a significant influence on the dielectric tunability. Furthermore, a high dielectric tunability can be achieved by adjusting an appropriate positive temperature gradient, the quantum fluctuation strength, and the four-spin interaction strength.
Direct imaging of core-shell structure in silver-gold bimetallic nanoparticles
Authors: Li Z. Y. , Yuan J. , Chen Y. , Palmer R. E. , Wilcoxon J. P.
Published: December 2005

High-angle annular dark field imaging in the electron microscope has been exploited to reveal the internal structure of monodispersed, bimetallic gold (Au) - silver (Ag) nanoparticles of ∼4nm diameter, prepared using a seed-growth wet chemical method and passivated with an organic layer. Starting with a 3 nm Ag seed particle, deposition of Au atoms to a final overall atomic ratio of Ag:Au=1:2 leads to nanoparticles with an Ag-rich core and an Au-rich shell, as expected. If the overall atomic ratio is 2:1, the core∕shell structure is not observed. The physical significance of these observations is discussed in terms of the stability of particles of nanoscale dimensions.
Packing-dependent pore structures in single-walled carbon nanotube arrays
Authors: Sun C. H. , Li F. , Cheng H. M. , Lu G. Q.
Published: December 2005

Based on a self-similar array model of single-walled carbon nanotubes (SWNTs), the pore structure of SWNT bundles is analyzed and compared with that obtained from the conventional triangular model and adsorption experimental results. In addition to the well known cylindrical endo-cavities and interstitial pores, two types of newly defined pores with diameters of 2–10 and 8–100 nm are proposed, inter-bundle pores and inter-array pores. In particular, the relationship between the packing configuration of SWNTs and their pore structures is systematically investigated.
Single standing carbon nanotube array in gate holes using a silicon nitride cap layer
Authors: Lim Sung Hoon , Yoon Hyun Sik , Moon Jong Hyun , Park Kyu Chang , Jang Jin
Published: December 2005

We studied the growth of a single standing carbon nanotube (CNT) which was grown by plasma-enhanced chemical vapor deposition in the gate hole formed by conventional photolithography in the silicon nitride. The number of CNT per hole increases with increasing the gate hole diameter and a single CNT could be grown in a 3μm hole. A single standing CNT in a gate hole exhibited the turn-on field of 1.6V∕μm and the current density of 16μA at 3.3V∕μm. The emission currents follow the Fowler–Nordheim equation with a field enhancement factor of 1.14×107.
Highly directional emission via coupled surface-plasmon tunneling from electroluminescence in organic light-emitting devices
Authors: Feng Jing , Okamoto Takayuki , Kawata Satoshi
Published: December 2005

We report that highly directional electroluminescence from top-emitting organic light-emitting devices (TEOLEDs) can be achieved by using a two-dimensionally periodically corrugated silver film as a cathode and an organic dye with a narrow bandwidth of emission spectrum as an emitting material. The resonant excitation of surface plasmons on the silver film interfaces contributes to the light transmission through the silver cathode and to the directional emission. The TEOLEDs with a europium complex as an emissive layer show beam divergence of less than 4° and the beam direction is controlled by periodicity of the corrugation.
Complexation of pyrrolidinofullerenes and zinc-phthalocyanine in a bilayer organic solar cell structure
Authors: Koeppe Robert , Sariciftci N. Serdar , Troshin Pavel A. , Lyubovskaya Rimma N.
Published: December 2005

Bilayer organic solar cells were prepared using zinc-phthalocyanine (ZnPc) and a novel, highly soluble pyrollidinofullerene bearing three chelating pyridyl groups (PyF). The formation of supramolecular complexes between the two compounds is indicated by a significantly increased solubility of ZnPc in dichloromethane upon addition of the PyF. Spin-coating a film of PyF on a vacuum-evaporated film of ZnPc results in a solar cell yielding short circuit current (Isc) densities of 3mA∕cm2 and open-circuit voltages (Voc) of about 0.4V under 100mW∕cm2 simulated AM1.5 illumination. Solar cells prepared by substituting the PyF with a fullerene derivative forming no complexes with ZnPc show significantly lower photovoltaic conversion efficiencies.
Knowledge Diffusion in Localised Economies of SMEs: The Role of Local Supporting Organisations
Authors: Dimitriadis Nikos , Simpson Mike , Andronikidis Andreas
Published: December 2005

The aim of this paper is to discuss the role of various socioeconomic actors in the diffusion of knowledge in localised economies of small and medium sized economics SMEs. The ability of industrial districts to diffuse knowledge quickly and effectively is frequently mentioned as their major advantage, but the actual process has still to be explored. Issues such as the characteristics of localised economies and the relationship between information flow and knowledge diffusion are discussed. A sample of thirty entrepreneurs was contacted and interviewed in Kastoria, a major furcoat production area and Greece's only authentic industrial district. Major findings suggest that the information needs of SMEs have changed in favour of more external and formal information. The role of various local socioeconomic organisations is subsequently becoming more important in the diffusion and creation of knowledge. Policy implications include the creation of a regional network between all the local actors in the form of a discussion forum, the development of an information centre, the increased use of information technologies, the employment of a specialised workforce from outside the district, and the introduction of training programmes.
A Government-Funded Internet Portal as a Promoter of Regional Cluster Relationships: A Case Study from the Australian Wine Industry
Authors: Sellitto Carmine , Burgess Stephen
Published: December 2005

This paper reports on a study that examined the relationship between a small winery cluster and the implementation of a government-sponsored Internet portal—the WinesOfGippsland.com site. Literature relating to industry clusters and Internet portals is examined to identify the beneficial features associated with portals and clusters. The paper makes a link between portal benefits and those typically associated with industry clusters, with the subsequent implications for policy. The study found that the winery business experience after portal implementation enhanced relationships between small wine producers, resulting in outcomes that included resource sharing, informal knowledge exchanges, and innovative practices that resulted in new product development. Indeed, these types of benefits tend also to be reported in successful clusters. Moreover, the authors argue that government policy may achieve more favourable outcomes in promoting e-commerce and Internet adoption in regional areas by identifying established business clusters (more so than ad hoc related groups) that can use their already established relationships quickly and appropriately to leverage the business benefits associated with new technologies.
Clustering Small Enterprise: Lessons from Policy Experience in New Zealand
Authors: Perry Martin
Published: December 2005

Doubts have been raised about the value of cluster-promotion policy given the lack of agreement over how clusters are identified. Such criticism overlooks how clusters are sometimes a mode of inquiry rather than a specific pattern of industrial location. The desire to promote business clusters is connected to a real phenomenon, but policy needs to acknowledge that exemplar clusters do not provide a role model for how other local economies may develop and that industry and market characteristics affect the significance of clustering. Efforts to promote business clusters in New Zealand show how the perceptions of cluster opportunities by business managers differ from those expected by policymakers. A review of twenty-five cluster initiatives identifies six ways that the projects question widespread opportunity to benefit from encouraging localised business collaboration: (1) value-chain division, (2) conditions on cooperation, (3) the need to go national, (4) facilitator dependence, (5) need for a leader, and (6) missing clusters. Policy intervention should be based on determining how best to work with groups of variable significance and character rather than being driven by idealised interpretations of cluster development.
The Orbital Period of Nova V2540 Ophiuchi (2002)
Authors: Ak Tansel , Retter Alon , Liu Alex
Published: December 2005

We present the results of 26 nights of CCD photometry of the nova V2540 Oph (2002) from 2003 to 2004. We find a period of 0.284781 ± 0.000006 d (6.8347 ± 0.0001 h) in the data. Since this period was present in the light curves taken in both years, with no apparent change in its value or amplitude, we interpret it as the orbital period of the nova binary system. The mass–period relation for cataclysmic variables yields a secondary mass of about 0.75 ± 0.04 M⊙. From maximum magnitude–rate of decline relation, we estimate a maximum absolute visual magnitude ofMV= −6.2 ± 0.4 mag. This value leads to an uncorrected distance modulus of (m–M) = 14.7 ± 0.7. By using the interstellar reddening for the location of V2540 Oph, we find a rough estimate for the distance of 5.2 ± 0.8 kpc. We propose that V2540 Oph is either (1) a high-inclination cataclysmic variable showing a reflection effect of the secondary star, or having a spiral structure in the accretion disc, (2) a high-inclination intermediate polar system, or less likely (3) a polar.
Galaxy Groups: Proceedings from a Swinburne University Workshop
Authors: Kilborn Virginia A. , Bekki Kenji , Brough Sarah , Doyle Marianne T. , Evstigneeva Ekaterina A. , Forbes Duncan A. , Koribalski Bärbel S. , Owers Matthew S. , Power Chris , Drinkwater Michael J. , Rohde David J. , Blake Christopher A. , Couch Warrick J. , Pracy Michael B. , Gibson Brad K.
Published: December 2005

We present the proceedings from a two-day workshop held at Swinburne University on 2005 May 24–25. The workshop participants highlighted current Australian research on both theoretical and observational aspects of galaxy groups. These proceedings include short one-page summaries of a number of the talks presented at the workshop. The talks presented ranged from reconciling N-body simulations with observations, to the Hı content of galaxies in groups and the existence of ‘dark galaxies’. The formation and existence of ultra-compact dwarfs in groups, and a new supergroup in Eridanus were also discussed.
The Legacy of Early Uranium Efforts in Australia, 1906 - 1945: From Radium Hill to the Atomic Bomb and Today
Authors: Mudd Gavin M.
Published: December 2005

The existence of uranium minerals has been documented in Australia since the late nineteenth century, and uranium-bearing ores were discovered near Olary ('Radium Hill') and in the Gammon Ranges (Mount Painter) in north-eastern South Australia early in the twentieth century. This occurred shortly after the discovery of radioactivity and the isolation of radium, and a mining rush for radium quickly began. At Radium Hill, ore was mined and concentrated on site before being transported to Woolwich in Sydney, where the radium and uranium were extracted and refined. At Mount Painter, the richness of the ore allowed direct export overseas. The fledgling Australian radium industry encountered many difficulties, with the scale of operations generally much smaller than at overseas counterparts. Remoteness, difficulties in treating the ore, lack of reliable water supplies and labour shortages all characterized the various attempts at exploitation over a period of about 25 years to the early 1930s. Hope in the potential of the industry, however, was eternal. When the British were working with the Americans during the Second World War to develop the atomic bomb, they secretly requested Australia to undertake urgent and extensive studies into the potential supply of uranium. This led to no exports but it did lay the groundwork for Australia's post-war uranium industry that has dominated the nation's nuclear diplomacy ever since. Some three decades later, the modest quantity of radioactive waste remaining at Woolwich was rediscovered, creating a difficult urban radioactive waste dilemma. The history of both the pre-war radium–uranium industry and Australia's involvement in the war-time exploration work is reviewed, as well as the radioactive waste problems resulting from these efforts, which, despite their relatively small scale, persist and present challenges in more modern times.
Assessing the influence of shrubs and their interspaces on enhancing infiltration in an arid Australian shrubland.
Authors: Dunkerley DL
Published: December 2005

In assessments of rangeland condition, the fraction of the soil surface lying beneath the canopy of a plant
has been widely adopted as a measure of soil protection afforded by the plant, and of the size of the area
of altered micro-environment associated with it. In this local environment, various factors produce more
permeable soils that allow faster uptake of rainwater than occurs through soils in the open interspaces
between plants, or in degraded rangeland where plant canopy cover has been diminished. However, the
nature and location of the transition from 'shrub' to 'interspace' hydrologic behaviour has remained illdefined,
and the appropriateness of this two-phase subdivision of shrublands remains to be established.
This paper reports on a study designed to begin this process by assessing the size of the 'zone of
influence' exerted by bluebush shrubs (Maireana spp.) on water infiltration rates in their vicinity, using a
test site at Fowlers Gap, north of Broken Hill, NSW.
Using radial transects of infiltrometer data extending from close to the stem into the open interspace, it is
shown that infiltration rates do not change abruptly at the canopy margin. Rather, enhanced water uptake
persists for some distance into the interspace. According to present results, the plant canopy only covers
the central one-third of this larger zone of influence, and so provides an inadequate measure of it.
Measures of the persistence in time and lateral extent of the zone of influence may provide more
meaningful and more sensitive measures of rangeland condition in the arid and semi-arid shrublands.
Discrimination of arid vegetation composition with high resolution CASI imagery.
Authors: Lewis M
Published: December 2005

CASI (Compact Airborne Spectrographic Imager) airborne imagery, with high spectral and spatial resolution, was evaluated for the discrimination of composition and variation in arid vegetation at Fowlers Gap Arid Zone Research Station in western New South Wales. The imagery was calibrated to surface reflectance using field reference spectra collected near the time of the overflight, and analysed in relation to reflectance spectra of plants at Fowlers Gap. Maps showing abundance of total perennial vegetation, chenopod shrubs and trees, were produced using methods that separated the vegetation contribution from mixed-pixel responses. Results of these analyses were compared with field data on percentage ground cover for 85 one hectare sample plots, collected within four weeks of the overflight. In all cases, the cover of vegetation that was discriminated and mapped was less than 25%. The study demonstrates that high-spectral resolution imagery, combined with new approaches to image analysis, offers considerable scope for discrimination of vegetation variation in arid landscapes. It is possible to spectrally discriminate and map the abundance of several functional vegetation components, even in sparse vegetation, and this information is particularly relevant for management applications. As imagery from high-spectral resolution sensors, both air- and satellite-borne, becomes more readily available in Australia, the benefits to be derived from these data will be more widely applied. Key words: arid vegetation, species composition, hyperspectral imagery, remote sensing, vegetation spectra
Changes in ant species composition and community organisation along grazing gradients in semi-arid rangelands of the Northern Territory.
Authors: Hoffmann B
Published: December 2005

The impact of cattle grazing on ant diversity, species composition and community organisation was investigated in the Victoria River District of the Northern Territory, using distance from water as a surrogate of grazing intensity. Two gradients were sampled, one on red earth at Kidman Springs (5 plots), the other on black cracking clay at Mount Sanford (6 plots). Sites were sampled in April (both sites) and October (Kidman Springs only)1998. The two sites supported distinctly different ant communities, with 70 species at Kidman Springs and 36 at Mount Sanford. Species richness and total abundance did not change significantly with distance from water, although species richness was always greatest at the most distant plot. However, multivariate analysis showed that ant species composition changed markedly. Despite large changes in species composition, the abundance of only six of the 24 most common species (two at Kidman Springs and four at Mount Sanford) were significantly correlated with grazing intensity. The abundance of Bassian taxa was promoted by grazing, whereas the species richness of Torresian taxa and the abundance and species richness of Widespread taxa were suppressed. Ant functional group analysis showed community organisation was resilient, with slight changes being primarily driven by Hot Climate Specialists and dependent on the season. However, the relative richness of five functional groups correlated significantly with grazing intensity, all negatively. Ant variables suppressed by grazing were positively associated with patch cover variables and litter, and negatively correlated with annual grass and bare ground, and may serve as indicators of rangeland condition. Key words: biodiversity, cattle grazing, indicators, piosphere, rangeland management, semi-arid, tropical savannas
Can social interactions affect food searching efficiency of cattle?
Authors: Ksiksi T , Laca EA
Published: December 2005

Experienced members of a herd of cattle, referred to as social models in this paper, may play an important part in the searching pattern of naive animals. Naive animals may distribute themselves more evenly because their expectations of preferred areas are not as developed as the expectations of experienced animals. We tested three treatments to investigate if social models tend to transmit information about places of grazing to naive ones or if food distribution tends to be more uniform when animals have less experience with the area. A fenced paddock with 192 trays spaced at about 5 m apart was used to conduct this experiment. Treatment one was the clumped distribution treatment (CDT). Food trays were placed as sets of four. Treatment two was the scattered distribution treatment (SDT). Food trays were placed evenly covering different areas of the paddock. In these two treatments, steers were allowed to find 32 trays with feed in the presence of a social model. Treatment three is a control (CT). Steers were allowed to find 32 trays containing feed with no social model present. The experiment lasted seven days and starting on day four, CDT had a higher FL/NL (ratio of found locations to new locations) than CT (P<0.05). This suggests that naive animals tend to be more efficient in finding preferred food locations in the presence of an experienced model. CDT had a higher FLNL than SDT on days three, six and seven of the experiment (P<0.05). This suggests that the initial distribution of food affected the searching efficiency of naive animals. Moreover, within three days steers in all three treatments did better than expected by chance in locating food. Key words: Grazing, searching, distribution, spatial memory
Studies of soil seedbanks in native and sown pastures in northern New South Wales
Authors: Lodge G. M.
Published: December 2005

Total and germinable soil seedbanks (litter and soil) were studied for a native pasture and three sown pastures (dominated by Phalaris aquatica L. cv. Sirosa) in northern New South Wales from 1993 to 1996. Soil core samples were taken from continuously grazed plots for both pasture types and two oversown treatments in the native pasture and from a spring-autumn rest treatment at the sown pasture sites. At each site above ground herbage mass was also estimated regularly as part of the Temperate Pasture Sustainability Key Program.
For all sites and treatments, the proportion of germinable seeds as a percentage of the total (dormant and germinable) seedbank ranged from 1–26% for the native pasture and 1–39% for the sown pastures. Germinable seed numbers ranged from 280 to 26,110 seeds per m2, while total seedbank numbers were from 6700 to 178,360 seeds per m2. Native pasture herbage mass was dominated by native perennial grasses, but seeds of these species were less than 20% of the total seed bank in all treatments in 1994 and 1995. At the sown pasture sites, most of the germinable (51–92%) and total (65–97%) seedbanks were either barnyard grass (Echinochloa crus-galli (L.) Beauv, annual ryegrass (Lolium rigidum Gaudin), subterranean clover (Trifolium subterraneum L.) or wireweed (Polygonum aviculare L.). Since seeds of annuals and other forbs generally dominated both the total and germinable seedbanks of these perennial grass-based pastures, these species were likely to increase over time.
Seeds of the sown perennial grass Phalaris aquatica L, cv. Sirosa were less than 1% of the total seedbanks in pastures sown in 1990 and less than 3% of those sown in 1979. With above average summer rainfall at the native pasture site in 1996 and prolific growth of redgrass, seeds of this species were 38–63% of the total and 11–29% of the germinable seedbank in May 1996. Except at this site and time, the species composition of the total and germinable seedbanks did not generally reflect the dominance of the above ground herbage mass of these pastures by perennial grasses.
Causes of the extinction of native mammals of the Western Division of New South Wales: an ecological interpretation of the nineteenth century historical record
Authors: Lunney Daniel
Published: December 2005

Twenty-four mammal species – predominantly the medium-sized, ground-dwelling mammals with a dependence on grass/herbs and seeds – disappeared forever from the landscape of the Western Division of New South Wales in a period of 60 years from first settlement in 1841. The present study examines the causes of this extinction episode by constructing a picture of the changing landscape from the historical record and interpreting the findings ecologically. The conclusions point to an extinction process that can be largely attributed to the impact of sheep, an impact that was exacerbated in the scarce and fragile refuges of the flat landscape in times of intense and frequent drought. This conclusion differs from those of many others, particularly Kerin in the Western Lands Review, who pointed to "the impact of feral animals, rather than overgrazing" as the cause of mammal extinctions, and Morton, who considered that the rabbit was "principally (although not entirely)" responsible for mammal extinctions in the rangelands. The rabbit plague in the Western Division from the early 1880s and the influx of foxes in the last years of the 19th century expedited the local demise of some species and even delivered the final blow to surviving remnant populations of a few species of native mammals but they were not the primary agent of extinction. Historical accounts give prominence to the rapidly growing wool industry in the 19th century. From its dominant position as an export commodity, wool became the chief means of the successful spread of colonial settlement. By 1853 there were about 300,000 sheep based at the southern end of the Darling on the watered frontages, which were all taken up by 1858. The west of the Darling was largely occupied by sheep farmers between 1859 and 1876. The history of settlement around Menindee from 1841 can be read as a devastating critique of the failure to realise that the west could not sustain a pattern of land use imposed on it from another world. The deterioration of the pastoral landscape was such that by the late 1880s the "walls of the pastoral fortresses... were beginning to crumble of their own accord, as the foundations on which they were built — the physical environment — altered under stresses...". The sequence of occupation and land use in the Western Division and the timing of the loss of native mammal species allows the conclusion to be drawn that it was sheep, and the way the land was managed for the export wool industry, that drove so many of the mammal species to extinction. The impact of ever-increasing millions of sheep on all frontages, through all the refuges, and across all the landscape by the mid 1880s is the primary cause of the greatest period of mammal extinction in Australia in modern times.
The extent and status of remnant vegetation in Queensland and its implications for statewide vegetation management and legislation
Authors: Wilson B.  A. , Neldner V. J. , Accad A.
Published: December 2005

Vegetation classification, survey and mapping provide key information underpinning the implementation of statewide vegetation management legislation and associated policies in Queensland. This paper summarises: (i) the Queensland Herbarium survey and mapping methods and land classification system and its role in vegetation management legislation; and, (ii) the current extent and rate of vegetation clearing by bioregion, sub-region and Broad Vegetation Group; (iii) and the amount of vegetation protected under legislated statewide bioregional and regional ecosystem thresholds. Information also is provided on the pre-clearing and current extent by 18 Broad Vegetation Groups and the area of non-remnant woody vegetation by bioregion. The implications for vegetation management are discussed, along with a comparison of clearing statistics derived from other studies that use different classification and mapping methodologies.
The majority of Queensland has relatively continuous native vegetation cover (82% remnant native vegetation remaining in 1999). The productive soils of the southern part of the Brigalow Belt, lowlands in South-east Queensland, New England Tableland and Central Queensland Coast have been, however, extensively cleared with 7–30% of remnant vegetation remaining. Between 1997 and 1999, the annual rate of remnant clearing in Queensland was 4460 km2 of which over 60% occurred in the Brigalow Belt bioregion. A greater proportion of this recent clearing occurred in Broad Vegetation Groups that are associated with less fertile and/or more arid parts of the State compared with pre 1997 clearing.
For bioregions and regional ecosystems where past clearing has been extensive, a substantial proportion (50–91%) of the remaining vegetation is protected by bioregional and regional ecosystem thresholds prescribed under statewide legislation and associated policies. For other bioregions and regional ecosystems, other factors such as rainfall, soil and areas of high conservation value are likely to play a larger role in determining the amount of vegetation protected. However, the effectiveness of the Queensland legislation cannot be assessed until regional planning processes have been completed and all criteria addressed.
A review of the potential role of greenhouse gas abatement in native vegetation management in Queensland's rangelands
Authors: Henry B. K. , Danaher T. , McKeon G. M. , Burrows W. H.
Published: December 2005

Concern about the risk of harmful human-induced climate change has resulted in international efforts to reduce greenhouse gas emissions to the atmosphere. We review the international and national context for consideration of greenhouse abatement in native vegetation management and discuss potential options in Queensland. Queensland has large areas of productive or potentially productive land with native woody vegetation cover with approximately 76 million ha with woody cover remaining in 1991. High rates of tree clearing, predominantly to increase pasture productivity, continued throughout the 1990s with an average 345,000 ha/a estimated to have been cleared, including non-remnant (woody regrowth) as well as remnant vegetation. Estimates of greenhouse gas emissions associated with land clearing currently have a high uncertainty but clearing was reported to contribute a significant proportion of Australia's total greenhouse gas emissions from 1990 (21%) to 1999 (13%). In Queensland, greenhouse emissions from land clearing were estimated to have been 54.5 Mt CO2-e in 1999. Management of native vegetation for timber harvesting and the proliferation of woody vegetation (vegetation thickening) in the grazed woodlands also represent large carbon fluxes. Forestry (plantations and native forests) in Queensland was reported to be a 4.4 Mt CO2-e sink in 1999 but there are a lack of comprehensive data on timber harvesting in private hardwood forests. Vegetation thickening is reported for large areas of the c. 60 million ha grazed woodlands in Queensland. The magnitude of the carbon sink in 27 million ha grazed eucalypt woodlands has been estimated to be 66 Mt CO2-e/a but this sink is not currently included in Australia's inventory of anthropogenic greenhouse emissions.
Improved understanding of the function and dynamics of natural and managed ecosystems is required to support management of native vegetation to preserve and enhance carbon stocks for greenhouse benefits while meeting objectives of sustainable and productive management and biodiversity protection.
Bore drain replacement in south-west Queensland: benefits and costs for land managers
Authors: Pegler Lachlan , Moore Renée , Bentley Delphine
Published: December 2005

The Bore Drain Replacement Project (BDRP) in south-west Queensland provided government subsidies to land managers to convert water distribution systems from open earth bore drains to piped water systems, thereby addressing Great Artesian Basin (GAB) sustainability issues. To fully evaluate the benefits and costs of the project for land managers, both a financial benefit-cost analysis and a study of land managers' perceptions were conducted.
The main benefit for land managers from bore drain replacement, was a substantial decrease in operating costs (mean decrease of 87%). Results of the financial benefit-cost analysis showed that the mean private benefit to total cost ratio (BP:CT) (0.86, at a real discount rate of 6%, over 10 years) was less than the break-even value of unity . The mean BP:CT (0.6) for land managers with less than 50% of bore drains on mulga (Acacia aneura F. Muell ex. Benth) land systems was also less than unity, while those land managers with bore drains predominately on mulga land systems had a mean BP:CT that only marginally exceeded unity (1.1). With a government subsidy (study mean 72%), the private benefits to private cost ratio (BP:CP), averaged across all land managers in the study, was 2.25. The break-even subsidy level for land managers was calculated as 17% of the total capital cost.
Land managers perceived a number of important benefits from bore drain replacement that were not included in the financial benefit-cost analysis, due to difficulty quantifying values. These included benefits from changes in grazing management, increased time-savings and an improved quality of life. In general, there were no changes documented in animal productivity, native and feral animal populations, or carrying capacity in the 18 months since piping, although potential changes for the future were identified. Some land managers noted improvements to natural resource condition near bore drains after closure, while most expected little deterioration in natural resource condition near the new water points.
Recommendations are made for ongoing funding support for bore drain replacement, including further monitoring and evaluation, with emphasis on conducting an economic public and private benefit-cost analysis. Land managers' capacity to pay, willingness to adopt change and public benefits of the project should be considered in cost sharing arrangements and determination of future government subsidy levels.
Ground cover in temperate native perennial grass pastures. I. A comparison of four estimation methods
Authors: Murphy S. R. , Lodge G. M.
Published: December 2005

Studies were conducted to compare visual estimates of ground cover and canopy cover by both inexperienced and experienced observers and to compare those estimates with those from more objective methods in native pastures in the high rainfall, temperate rangelands of northern NSW. Ground cover and canopy cover of 60 quadrats was estimated using visual, mapped area, digital image analysis and photo point quadrat methods. Inexperienced observers were trained by estimating ground cover of reference quadrats. Differences between mean visual estimates of ground cover and canopy cover for experienced and inexperienced observers were not significant (P>0.05). Mean ground cover estimates by the mapped area, digital image analysis and point quadrat methods were also not different from each other. The overall relationship between mean visual estimate and mean objective estimate of ground cover was non-linear (second order polynomial, R2 = 0.93), observers tending to underestimate in the mid-range (20 to 80%) of cover compared with objective methods. Mean visual estimate of ground cover was 73.7% compared with the mean objective estimate of 83.7%. Visual estimates of canopy cover (mean 34.6%) were highly correlated (R2 = 0.90) with those of the mapped area method (mean 34.3%) and the relationship was linear. Measurement of ground cover is a standard technique used in many pasture ecology and management studies and is increasingly being used by land managers to monitor pasture production and sustainability. Inexperienced observers were trained quickly and easily to estimate ground cover and canopy cover with sufficient accuracy to identify ranges of cover using visual estimation, indicating that the visual estimation technique should be suitable for estimating ground cover in land management research.
Vegetation changes in a semiarid tropical savanna, northern Australia: 1973 - 2002
Authors: Bastin Gary , Ludwig John , Eager Robert , Liedloff Adam , Andison Reginald , Cobiac Michael
Published: December 2005

We measured vegetation changes inside and outside two exclosures built in 1973 on red calcareous loam soils located in Conkerberry Paddock on Victoria River Research Station in northern Australia. These two exclosures were unburnt since their establishment in 1973 until exclosure 1 was unintentionally burnt late in the dry season (October) of 2001. Data from permanent transects and examples from photopoints illustrate that from mostly bare soils in 1973, total pasture biomass recovered relatively rapidly both inside and outside exclosures (in about five years). This initial recovery was primarily due to the establishment of annual grasses and forbs. After this five year period, there was a consistent increase in the biomass of perennial grasses, such as Heteropogon contortus and Dichanthium spp. Also in the first five years after exclosure, the exotic shrub, Calotropis procera,invaded the study area, but then largely disappeared in a period of lower wet-season rainfall in the late 1980s. The density of native tree species, particularly Hakea arborescens, Eucalyptus pruinosa and Lysiphyllum cunninghamii increased in general, but more so inside one or other of the exclosures. Although the late dry-season fire of 2001 reduced the density of larger H. arborescens and L. cunninghamii inside the exclosure at Site 1, this effect was not apparent for smaller trees and for trees outside this exclosure. Our findings show that savanna vegetation can change massively in the medium term (29 years) and that exclosure from cattle grazing can contribute to our understanding of the role of livestock in such change. However, exclosures by themselves do not provide adequate information about the processes leading to vegetation change replicated experimental studies are needed. That substantial increase in the biomass and proportion of perennial grasses occurred with light to moderate cattle grazing implies that these rangelands can be managed for production, although control of woody vegetation is an issue.
Native grassland management: a botanical study of two native grassland management options on a commercial cattle property
Authors: McGufficke B.
Published: December 2005

Variations in the botanical composition of two native grasslands, each managed differently, were investigated on a commercial cattle property in northern NSW. One grassland had not been fertilised, whilst fertiliser and subterranean clover had been applied by aerial application to the other grassland. Soils in both treatments had the same Bray 1 phosphorus level when the study was conducted. The fertilised grassland was stocked at triple the rate of the other grassland. Although more native species were recorded in the fertilised grassland many species had a lower frequency than in the unfertilised grassland; and introduced species tended to have a higher frequency in the fertilised grassland. ground cover was significantly higher in the fertilised grassland in spite of the greatly increased stocking rate.
Herbage condition assessment of an infertile range grassland based on site production potential.
Authors: Christie EK
Published: December 2005

The herbage production of mixed native mulga grassland communities, all differing in basal area, was measured between October and March each year over a four year period. The four seasons differed in total precipitation and length of, as well as continuity of the growing period. Basal area was found to be well correlated with peak standing grass biomass and with litter and root yield. Furthermore, basal area was found to be an adequate index of potential grass production irrespective of year. Basal area could be used as a determinant for condition assessment of these grassland communities growing on infertile soils, as well as an indicator of stocking rate. Photographic standards for field use are presented.
The Shrubs of Poplar Box (Eucalyptus populnea) Lands and their Biology.
Authors: Hodgkinson KC
Published: December 2005

Of the 25 species of shrubs common in poplar box lands, 17 are considered to have reached the status of being a "woody weed" in New South Wales and/or Queensland. Thickening up of scrub in pastoral areas appears to have been episodic after periods of above-average rainfall. Germination of seed may occur at most times of the year if soil moisture is high. Fire promotes germination of species with hard seeds (some Acacia, Cassia and Dodonaea spp.). Increased shrub density usually follows soil disturbance if seed is present, and once established, the individuals of most apecies appear to be long-lived. Productivity of shrub communities is commensurate with rainfall. The species are well adapted to tolerate drought and they retain leaves under extreme water stress. Most species flower and set seed each year in the spring and summer period but in more arid parts of poplar box lands some species reproduce opportunistically after good rainfall. In favourable conditions most species produce copious quantities of seed. Dormancy is common in seed recently shed and loss of dormancy may occur within months or up to 3 years after seed shed. All species are subject to invertebrate and vertebrate predation and death of individuals or whole populations may sometimes result. A few species are moderately palatable to domestic livestock and native herbivores; the majority are rarely eaten even by starving animals. The regenerative ability of shrubs following fire or grazing differs amongst species and is affected by shrub size.