Background Infection with Campylobacter is thought to account for about 5% - 14% of all food and waterborne diarrhoea cases worldwide. By international standards, New Zealand has extremely high rates of campylobacteriosis which are thought to be the highest reported rates worldwide. The incidence has been steadily increasing since 1980 (when the disease became notifiable), reaching a peak of cases in 2003 (396/100,000). Although different surveillance systems complicate international comparisons, New Zealand's particularly high rate still lacks a conclusive explanation. Aims This study investigates the geographical distribution of campylobacteriosis in New Zealand and the relative importance of factors assumed to be affecting the distribution of this disease, including those related to climate, landuse, water and food. The approach aims to explain why certain areas might increase the probability of becoming infected. Methodology A Geographical Information System (GIS) is used to visualise the disease rate, investigate potential disease clustering and identify outliers. Hierarchical regression, including the analysis of residuals, is applied to analyse the variables in their complex interrelation and to investigate whether there is statistical evidence explaining the geographical variation in campylobacteriosis. This study is undertaken at the territorial local authority level, as all required data are available at this spatial scale and covers the period 1997 to 2005. Results and conclusion There is a large geographical variation in campylobacteriosis across New Zealand, ranging from an average annual rate of 97/100,000 to 526/100,000 per territorial local authority (TLA). Generally, there is statistical evidence for global and local clustering of the disease rate. There are upper and lower outliers of campylobacteriosis in New Zealand; however, higher rates primarily appear in the South Island. The hierarchical modelling confirms statistical significance for some of the environmental and sociodemographic variables. The final model explains about 58% of the variation in campylobacteriosis, and the residuals reflect this variation relatively accurately in approximately 75% of all TLAs. Although the evaluation of the results is confronted with a number of challenges, it is concluded that socioeconomic and demographic factors are crucial factors in explaining the observed spatial patterns in the notification data.

No description available.

No description available.

Alluvial gold placers in Otago and northern Southland occur at several stratigraphic horizons within the Late Cretaceous - Recent sedimentary sequence. The gold is derived ultimately from primary sources in the Otago Schist. Poor correlation between the distribution of placers and that of the known primary deposits reflects repeated recycling of gold in the present drainage network and two precursor networks, each with substantially different architecture. The previous drainage networks were inundated and buried during marine or lacustrine transgression. There has been local addition of first cycle gold and immature detritus during each recycling phase. Most of the placer deposits are fluvial in origin but colluvial placers occur locally along the margins of several Central Otago ranges. Aeolian placers and marine placers are rare. Most of the gold in placers north of the Caples/Torlesse Terrane boundary is Au-Ag alloy, except in vicinity of the Hyde-Macraes Shear Zone, where α-Au-Ag-Hg alloy is also present. Conversely, α-Au-Ag-Hg alloy dominates in placers south of the Caples/Torlesse Terrane boundary, except those whose headwaters lie, or lay, in the Torlesse Terrane. These systems that cross the terrane boundary contain Au-Ag and Au-Ag-Hg alloys in the reach downstream of the boundary, and placers with their source in Aspiring Lithologic Association also contain both alloys. Textural and compositional maturity of the placer host generally increase with decreasing age, reach maxima at the Waipounamu Erosion Surface, and generally decrease in tandem with age above this surface. Exceptions occur in northern Southland, where quartz pebble conglomerate placers are actively forming. Fluvial quartz pebble conglomerate placers have not formed in a single sedimentary cycle. Instead, they have formed from precursor sediment where a high water table drives alteration of the labile component, and when uplift and erosion rates, topography and stream gradients are all sufficiently low to drive sedimentary recycling without significant input of low-grade basement detritus. The maturity of pre-marine examples (Taratu, Papakaio and Hogburn Formations) was enhanced by wave-reworking before final inundation during marine transgression. Colluvial placers in alluvial fans at the margins of Quaternary schist antiforms are repeatedly recycled into younger fan sediments during range growth. These ranges grow in width, as well as length and height, at the expense of the intervening basins, which become progressively narrower. The colluvial placers are ultimately reworked into a fluvial placer in an axial river between two ranges, which concentrates all of the colluvial gold into an incised channel once the widening ranges meet. Aeolian placers have formed from fluvial precursors in the semi-arid parts of the rain shadow east of the Southern Alps, particularly on the lower slope of ranges exposed to westerly winds. Silcrete and less common greywacke ventifacts are commonly associated with these placers. Progressive changes in gold particle shape by flattening during transport in fluvial systems has been the most important process in the concentration of gold in placers. Flattening changes the hydrodynamic behaviour of gold particles by increasing their surface area to volume ratio, thereby making them easier to entrain and enabling transport to lower energy parts of the fluvial system. Gold particle flatness determines whether transport or concentration occurs and there is a predictable relationship between particle flatness and transport distance. This relationship explains the typical occurrence of placers immediately downstream of terminal moraines, the confluence with steeper tributary streams and the mouth of incised gorges. In each case, gold with sub-critical flatness is deposited from a higher energy system or reach into a lower energy system or reach, and must be flattened to a critical state before further transport can occur. Chemical mobility of gold in groundwater occurs during uplift, commonly in association with sedimentary recycling. Secondary gold overgrowths are common in some placers and stitch or overgrow transport-induced features such as folds and abrasion marks. Chemical mobilisation and re-precipitation of gold is of minor importance, however, and results in volumetrically insignificant amounts of secondary gold. Increases in gold grain size upward through the section on both the local and the regional scale does not result from gold 'growth', but instead from preservation of progressively more proximal reaches of the host placers with decreasing age.

The rationale behind the research presented in this thesis grew from a perception that, historically, work that was seen to be

Graduation date: 1998

Thesis (Ph.D.)--University of Canterbury, 2007. / Typescript (photocopy). Includes bibliographical references (leaves 223-234). Also available via the World Wide Web.

Inaug.-diss.--Hamburg. / Lebenslauf. "Literatur": p. 94-96.

Thesis (Ph. D.)--University of Chicago, Dept. of Anthropology, August 2003. / Includes bibliographical references. Also available on the Internet.

In any study of the New Zealand economy today it is essential that the major feautures of her historical and geographical background be reviewed. The international ties brought about by her comparatively short history and the implications of her position in the South Pacific, both from the standpoint of climate and comparative isolation, have a vital part in the understanding of New Zealand today. [...]