7,658 research outputs found

    Assessment of vegetation condition and health at Claudelands Bush (Jubilee Bush; Te Papanui)

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    As the largest remnant indigenous natural area, Claudelands Bush is a key asset for Hamilton city. With a history including clearance, logging and grazing; high numbers of plant species have been lost from the bush. Some of these pressures still exist today such as drainage, invasion by adventive plant species, presence of animal pests and the small size of the bush fragment. These pressures continue to contribute to native species losses. To reduce species loss and improve vegetation condition and biodiversity, management has been taking place in the area since the 1980’s. Management included planting of native species, weeding of the bush, construction of wind breaks and boardwalks

    Comparison of laser performance for diode-pumped Tm:YLF of various doping concentrations

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    Single-end-pumped laser performance of 2, 4, and 6at.% Tm-doped YLF rods is reported. For the pumping configuration employed, crystal fracture was observed to occur for a thermal load per unit absorption length of ~13W/cm. The 2at.% Tm-doped crystal was found to have a quantum yield of ~90% of that of 4at.% Tm. However, due to a lower thermal loading density, the maximum possible incident pump power is predicted to be >60% higher, hence offering a greater output power per rod for the lower doping concentration. Power scaling considerations are discussed with reference to cross-relaxation, upconversion, and thermal loading of the host crystal

    Galaxy correlations and the BAO in a void universe: structure formation as a test of the Copernican Principle

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    A suggested solution to the dark energy problem is the void model, where accelerated expansion is replaced by Hubble-scale inhomogeneity. In these models, density perturbations grow on a radially inhomogeneous background. This large scale inhomogeneity distorts the spherical Baryon Acoustic Oscillation feature into an ellipsoid which implies that the bump in the galaxy correlation function occurs at different scales in the radial and transverse correlation functions. We compute these for the first time, under the approximation that curvature gradients do not couple the scalar modes to vector and tensor modes. The radial and transverse correlation functions are very different from those of the concordance model, even when the models have the same average BAO scale. This implies that if void models are fine-tuned to satisfy average BAO data, there is enough extra information in the correlation functions to distinguish a void model from the concordance model. We expect these new features to remain when the full perturbation equations are solved, which means that the radial and transverse galaxy correlation functions can be used as a powerful test of the Copernican Principle.Comment: 12 pages, 8 figures, matches published versio

    Key ecological sites of Hamilton City: Volume 1

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    Ecological sites of significance previously identified in 2000 were reviewed in 2011. Natural vegetation in areas acquired by the city since 2000 was also surveyed to identify any new key sites. In total seventy key sites that met the Waikato Regional Council Regional Policy Statement criteria for ecological significance were identified across Hamilton City. Of the original key sites, the total area covered by sites, average site size and overall quality of sites had increased between the 2000 and 2011 surveys. This was due to restoration efforts across the city by Hamilton City Council and the community. Vegetation restoration efforts have had other biodiversity and ecological benefits such as providing additional habitat for the city’s increasing tui population. Key sites are not spread evenly across the city or across landform types. Most key sites are either in gullies or adjoining the Waikato River. Less than 1% of urban alluvial plains and peat bogs are key sites. Two sites on private land have degraded and no longer meet the ecological significance criteria in 2011. The current survey utilised a standard methodology focused on vegetation types. There will be other significant sites not identified including sites with significant fauna values but a detailed and costly survey would be required to identify all such sites. The 1.5% of the city area covered by key sites is well below the 10% minimum recommended to prevent biodiversity decline in urban areas. Areas where vegetation restoration has begun in the city have the potential to expand existing key sites or develop new sites if council and community efforts continue in the future. The Council and its restoration partners should continue to seek ways of increasing native vegetation cover in Hamilton City and restoration of the distinctive gully landform remains the best option
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