91,089 results

  • Industrial Agglomeration, Geographic Innovation and Total Factor Productivity: The Case of Taiwan

    Chang, Chia-Lin; Oxley, L. (2008)

    Discussion / Working Papers
    University of Canterbury Library

    RePEc Working Paper Series: No. 14/2008

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  • Testing for Energy Market Integration in China

    Ma, H.; Oxley, L.; Gibson, J. (2008)

    Discussion / Working Papers
    University of Canterbury Library

    RePEc Working Paper Series: No. 12/2008

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  • Use of floral resources by the lacewing Micromus tasmaniae and its parasitoid Anacharis zealandica, and the consequences for biological control by M. tasmaniae

    Robinson, Katherine A.

    Thesis
    Lincoln University

    Arthropod species that have the potential to damage crops are food resources for communities of predators and parasitoids. From an agronomic perspective these species are pests and biocontrol agents respectively, and the relationships between them can be important determinants of crop yield and quality. The impact of biocontrol agents on pest populations may depend on the availability of other food resources in the agroecosystem. A scarcity of such resources may limit biological control and altering agroecosystem management to alleviate this limitation could contribute to pest management. This is a tactic of ‘conservation biological control’ and includes the provision of flowers for species that consume prey as larvae but require floral resources in their adult stage. The use of flowers for pest management requires an understanding of the interactions between the flowers, pests, biocontrol agents and non-target species. Without this, attempts to enhance biological control might be ineffective or detrimental. This thesis develops our understanding in two areas which have received relatively little attention: the role of flowers in biological control by true omnivores, and the implications of flower use by fourth-trophic-level life-history omnivores. The species studied were the lacewing Micromus tasmaniae and its parasitoid Anacharis zealandica. Buckwheat flowers Fagopyrum esculentum provided floral resources and aphids Acyrthosiphon pisum served as prey. Laboratory experiments with M. tasmaniae demonstrated that although prey were required for reproduction, providing flowers increased survival and oviposition when prey abundance was low. Flowers also decreased prey consumption by the adult lacewings. These experiments therefore revealed the potential for flowers to either enhance or disrupt biological control by M. tasmaniae. Adult M. tasmaniae were collected from a crop containing a strip of flowers. Analyses to determine the presence of prey and pollen in their digestive tracts suggested that predation was more frequent than foraging in flowers. It was concluded that the flower strip probably did not affect biological control by lacewings in that field, but flowers could be significant in other situations. The lifetime fecundity of A. zealandica was greatly increased by the presence of flowers in the laboratory. Providing flowers therefore has the potential to increase parasitism of M. tasmaniae and so disrupt biological control. A. zealandica was also studied in a crop containing a flower strip. Rubidium-marking was used to investigate nectar-feeding and dispersal from the flowers. In addition, the parasitoids’ sugar compositions were determined by HPLC and used to infer feeding histories. Although further work is required to develop the use of these techniques in this system, the results suggested that A. zealandica did not exploit the flower strip. The sugar profiles suggested that honeydew had been consumed by many of the parasitoids. A simulation model was developed to explore the dynamics of aphid, lacewing and parasitoid populations with and without flowers. This suggested that if M. tasmaniae and A. zealandica responded to flowers as in the laboratory, flowers would only have a small effect on biological control within a single period of a lucerne cutting cycle. When parasitoids were present, the direct beneficial effect of flowers on the lacewing population was outweighed by increased parasitism, reducing the potential for biological control in future crops. The results presented in this thesis exemplify the complex interactions that may occur as a consequence of providing floral resources in agroecosystems and re-affirm the need for agroecology to inform the development of sustainable pest management techniques.

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  • Proceedings of the Rural Economy and Society Section of the Sociological Association of Aotearoa (N.Z.)

    Fairweather, John R.

    Working or discussion paper
    Lincoln University

    This Discussion Paper records the 14 papers presented in the Rural Economy and Society Section of the Sociological Association of Aotearoa (New Zealand) held at Lincoln University 7-9 December, 1990. The papers cover development issues, rural history, contemporary research and issues relating to the discipline of rural sociology in New Zealand. The development paper examines landownership in Northern England and the tensions surrounding different land uses. The history papers examine the impacts of transport technology, long term trends in agriculture exports, and Shelley's activities in rural education in Canterbury. The contemporary research papers, while wide ranging, include common themes such as how farm people have responded to the economic downturn in recent years by seeking off farm income. Another focus is the rural community with one paper examining local politics and another paper examining public drinking. The disciplinary papers look back at our rural research and then examine prospects and priorities for research in future. This discussion paper includes the full text of the following papers: Olivia Wilson, Landownership and rural development in Britain: a case study of the North Pennines (extended extract); James Watson, Rural New Zealand and the second industrial revolution; Neville Bennet, Cycles and booms in New Zealand agriculture exports (abstract only); Box, car and ace: Shelley in rural Canterbury, 1920-1936; Valerie Walton, Women's economic contribution to the farm; Margaret Begg, Dairy farm women; Richard Le Heron, Mike Roche, Tom Johnston and Susan Bowler, Pluriactivity in New Zealand's agro-commodity chains; Ian Gray, Issues and non-issues in rural local politics; Alison Loveridge, Formal qualifications and farm employees: does getting school certificate really help people become farm owners?; John Fairweather and Hugh Campbell, Public drinking and social organisation in Methven and MT. Somers; Ian Carter and Alison Loveridge, The strange absence of New Zealand rural sociology; Trevor Showdon, Rural sociology in New Zealand: dimensions; interdisciplinary intersections, institutional settings and future research.

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  • Does forage enrichment promote increased activity in captive capuchin monkeys (Cebus apella)?

    Dutton, Paul E.

    Thesis
    Lincoln University

    In their native habitat of Central and South America, capuchin monkeys (Cebus) spend 45% to 55% of their day foraging and a further 20% travelling. Once these monkeys are introduced into captive environments their diets are selective, seasonal and presented to them by their keepers. The captive environment often leads to various behavioural abnormalities and compensatory behaviours or stereotypies. To address this issue, environmental enrichment can be employed to reduce, cure or prevent such an occurrence. Enrichment can reduce stress, while increasing animal well-being and health in captivity. Despite previous work a better understanding of enrichment, for most neo-tropical primate species, is necessary, in order to improve their captive lifestyles. Feeding of captive primates is more complex than providing a balanced nutritional diet as it must also meet their ethological needs. The manipulation of the presentation of the diet has been shown to significantly decrease the incidence of resting, while significantly increasing the incidence of playing, grooming, foraging and manual manipulation of dietary items. Eleven capuchin monkeys were presented with four different feeding treatments (i.e. cut food presented in bowls, cut food presented around the enclosure, uncut food presented around the enclosure and novel feeding devices presented around the enclosure) from December 2007 until May 2008. At the start of every month one of three feeding treatments was introduced with the cut food in bowls feeding treatment interleaved between the treatments. The different feeding treatments required the monkeys to search for their food, break-up their food into manageable sizes, and obtain food in touch-, tool- and manipulative-dependent methods in order to allow the monkeys an opportunity to display increased activity more in line with their wild conspecifics. The capuchins displayed a period of intense foraging directly following feeding. This period significantly increased (from 44 to 121 min.), along with foraging events and the proportion of time spent foraging, which was more in line with their wild conspecifics. In addition, the frequency of occurrence and the proportion of time spent on locomotion and resting was shown to decrease. Also, abnormal behaviours ceased to occur during the study. Environmental enrichment is a useful tool for providing stimulation, redistributing activity levels more in line with wild conspecifics and to combat abnormal and compensatory behaviours.

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  • Microbial factors associated with the natural suppression of take-all wheat in New Zealand

    Chng, Soon F.

    Thesis
    Lincoln University

    Take-all, caused by the soilborne fungus, Gaeumannomyces graminis var. tritici (Ggt), is an important root disease of wheat that can be reduced by take-all decline (TAD) in successive wheat crops, due to general and/or specific suppression. A study of 112 New Zealand wheat soils in 2003 had shown that Ggt DNA concentrations (analysed using real-time PCR) increased with successive years of wheat crops (1-3 y) and generally reflected take-all severity in subsequent crops. However, some wheat soils with high Ggt DNA concentrations had low take-all, suggesting presence of TAD. This study investigated 26 such soils for presence of TAD and possible suppressive mechanisms, and characterised the microorganisms from wheat roots and rhizosphere using polymerase chain reaction (PCR) and denaturing gradient gel electrophoresis (DGGE). A preliminary pot trial of 29 soils (including three from ryegrass fields) amended with 12.5% w/w Ggt inoculum, screened their suppressiveness against take-all in a growth chamber. Results indicated that the inoculum level was too high to detect the differences between soils and that the environmental conditions used were unsuitable. Comparison between the Ggt DNA concentrations of the same soils collected in 2003 and in 2004 (collected for the pot trial), showed that most soils cropped with 2, 3 and 4 y of successive wheat had reduced Ggt DNA concentrations (by 195-2911 pg g-1 soil), and their disease incidences revealed 11 of the 29 test soils with potential take-all suppressiveness. Further pot trials improved the protocols, such that they were able to differentiate the magnitudes of suppressiveness among the soils. The first of the subsequent trials, using 4% w/w Ggt inoculum level, controlled conditions at 16°C, 80% RH with alternate 12 h light/dark conditions, and watering the plants twice weekly to field capacity (FC), screened 13 soils for their suppressiveness against take-all. The 13 soils consisted of 11 from the preliminary trial, one wheat soil that had been cropped with 9 y of wheat (considered likely to be suppressive), and a conducive ryegrass soil. The results revealed that 10 of these soils were suppressive to take-all. However, in only four of them were the effects related to high levels of microbial/biological involvement in the suppression, which were assessed in an experiment that first sterilised the soils. In a repeat trial using five of the soils H1, H3, M2, P7 (previously cropped with 3, 3, 4 and 9 y successive wheat, respectively) and H15 (previously cropped with 5 y of ryegrass), three of them (H1, H3 and M2) had reduced Ggt DNA concentrations (>1000 pg g-1 soil reductions), and were confirmed to be suppressive to take-all. A pot trial, in which 1% of each soil was transferred into a γ-irradiated base soil amended with 0.1% Ggt inoculum, indicated that soils H1 and H3 (3 y wheat) were specific in their suppressiveness, and M2 (4 y wheat) was general in its suppressiveness. The microbial communities within the rhizosphere and roots of plants grown in the soils, which demonstrated conduciveness, specific or general suppressiveness to take-all, were characterised using PCR-DGGE, and identities of the distinguishing microorganisms (which differentiated the soils) identified by sequence analysis. Results showed similar clusters of microorganisms associated with conducive and suppressive soils, both for specific and general suppression. Further excision, re-amplification, cloning and sequencing of the distinguishing bands showed that some actinomycetes (Streptomyces bingchengensis, Terrabacter sp. and Nocardioides sp.), ascomycetes (Fusarium lateritium and Microdochium bolleyi) and an unidentified fungus, were associated with the suppressive soils (specific and general). Others, such as the proteobacteria (Pseudomonas putida and P. fluorescens), an actinomycete (Nocardioides oleivorans), ascomycete (Gibberella zeae), and basidiomycete (Penicillium allii), were unique in the specific suppressiveness. This indicated commonality of some microorganisms in the take-all suppressive soils, with a selected distinguishing group responsible for specific suppressiveness. General suppressiveness was considered to be due to no specific microorganisms, as seen in soil M2. An attempt to induce TAD by growing successive wheat crops in pots of Ggt-infested soils was unsuccessful with no TAD effects shown, possibly due to variable Ggt DNA concentrations in the soils and addition of nutrients during the experiment. Increasing numbers of Pseudomonas fluorescens CFU in the rhizosphere of plants, during successive wheat crops was independent of the Ggt DNA concentrations and disease incidence, suggesting that increases in P. fluorescens numbers were associated with wheat monoculture. This study has demonstrated that TAD in New Zealand was due to both specific and general suppressiveness, and has identified the distinguishing microorganisms associated with the suppression. Since most of these distinguishing microorganisms are known to show antagonistic activities against Ggt or other soilborne pathogens, they are likely to act as antagonists of Ggt in the field. Future work should focus on validating their effects either individually, or interactively, on Ggt in plate and pot assays and under field conditions.

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  • Modelling the spread of invasive species across heterogeneous landscapes

    Pitt, Joel P. W.

    Thesis
    Lincoln University

    Invasive species are well known to cause millions of dollars of economic as well as ecological damage around the world. New Zealand, as an island nation, is fortunate because it has the opportunity to regulate and monitor travel and trade to prevent the establishment of new species. Nevertheless foreign species continue to arrive at the borders and continue to cross them, thus requiring some form of management. The control and management of a new incursion of an invasive species would clearly benefit from predictive tools that might indicate where and how quickly the species is likely to spread after it has established. During the process of spread an invasing species must interact with a complex and heterogeneous environment and the suitability of the habitat in a region determines whether it survives. Many dispersal models ignore such interactions and while they may be interesting theoretical models, they are less useful for practical management of invasive species. The purpose of this study was to create and investigate the behaviour of a spatially explicit model that simulates insect dispersal over realistic landscapes. The spatially explicit model (Modular Dispersal in GIS, MDiG) was designed as am open-source modular framework for dispersal simulation integrated within a GIS. The model modules were designed to model an an approximation of local diffusion, long distance dispersal, growth, and chance population mortality based on the underlying suitability of a region for establishment of a viable population. The spatially explicit model has at its core a dispersal module to simulate long distance dispersal based an underlying probability distribution of dispersal events. This study illustrates how to extract the frequency of long distance dispersal events, as well as their distance, from time stamped occurrence data, to fit a Cauchy probability distribution that comprises the dispersal module. An investigation of the long distance dispersal modules behaviour showed that, in general, it generated predictions of the rate of spread consistent with those of analytical partial differential and integrodifference equations. However, there were some differences. Spread rate was found to be mainly dependent on the measurement technique used to determine the invasion front or boundary, therefore an alternative method to determine the boundary of a population for fat-tailed dispersal kernels is presented. The method is based on the point of greatest change in population density. While previously it was thought that number of foci rather than foci size was more important in stratified dispersal and that finer resolution simulations would spread more quickly, simulations in this study showed that there is an optimal resolution for higher spread rates and rate of area increase. Additionally, much research has suggested that the observed lag at the beginning of an invasion may be due to lack of suitable habitats or low probability of individuals striking the right combination of conditions in a highly heterogeneous environment. This study shows an alternative explanation may simply be fewer dispersal event sources. A case study is described that involved the application of the spatially explicit dispersal model to Argentine ant spread to recreate the invasion history of that species in New Zealand. Argentine ant is a global invasive pest which arrived in New Zealand in 1990 and has since spread to both main islands of New Zealand, primarily through human mediated dispersal. The spatially explicit simulation model and its prediction ability were compared to that of a uniform spread model based on equivalent total area covered. While the uniform spread model gave more accurate predictions of observed occurrences early in the invasion process it was less effective as the invasion progressed. The spatially explicit model predicted areas of high probability of establishment (hot spots) consistent with where populations have been found but accuracy varied between 40-70% depending on the year of the simulation and parameter selection. While the uniform spread model sometimes slightly outperformed or was equivalent to the simulation with respect to accuracy early in the invasion process, it did not show the relative risk of establishment and was less effective later in the invasion when stochastic random events generated by the simulation model were averaged to represent trends in the pattern of spread. Additionally, probabilistic predictions as generated by the spatially explicit model allow the uncertainty of prediction to be characterised and communicated. This thesis demonstrates that heterogeneous spread models can give more insight and detail than one dimensional or homogeneous spread models but that both can be useful at different stages of the invasion process. The importance of compiling appropriate data on dispersal and habitat suitability to aid invasion management has been highlighted. Additionally, a number of important hypotheses that need to be addressed to increase understanding of how species interact with the complex environment, have been identified and discussed.

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  • The role of resource subsidies in enhancing biological control of aphids by hoverflies (Diptera: Syrphidae)

    Laubertie, Elsa

    Thesis
    Lincoln University

    In this thesis, experiments were conducted in the laboratory and the field to determine whether the provision of floral resources to hoverflies could enhance the biological control of aphids. The overall aim was to clarify hoverfly behaviour and ecology in an agroecosystem in order to understand the potential of these insects for biocontrol under a conservation biological control (CBC) regime. A preliminary experiment in New Zealand compared the effect of different coloured water-traps on catches of the hoverflies Melanostoma fasciatum (Macquart) and Melangyna novaezelandiae (Macquart). Significantly more individuals were caught in completely yellow traps than in traps with green outer walls and yellow inner walls or in completely green traps. This suggested that if a measure of hoverfly numbers relating to a particular distance along a transect is required, consideration should be given to the ability of hoverflies to detect yellow traps from a distance. The use of traps that are green outside would more accurately reflect the local abundance of hoverflies, as the insect would be likely to see the yellow stimulus only when above or close to the trap. Also, the addition of rose water significantly increased the number of M. fasciatum caught. From a suite of flowering plants chosen for their ability in other studies to increase hoverfly visit frequencies, laboratory experiments were conducted in France to determine the plant’s effectiveness at enhancing Episyrphus balteatus (De Geer) ‘fitness’, and to evaluate whether adult feeding on flowers was related to performance. Phacelia (Phacelia tanacetifolia Bentham cv. Balo), followed by buckwheat (Fagopyrum esculentum Moench cv. Katowase) and coriander (Coriandrum sativum L.) gave the optimal reproductive potential of female E. balteatus. There was no correlation between pollen and nectar consumption, and there was no discernible positive correlation between the quantity of pollen ingested and the resulting female performance. Phacelia and buckwheat were then studied as resource subsidies in the field in New Zealand. The effect of incorporating phacelia or buckwheat in the margins of 5 m x 5 m broccoli plots was tested for hoverfly activity and floral ‘preferences’. Hoverflies which had fed on phacelia and buckwheat pollen were found up to 17.5 m from the floral strips and females of M. fasciatum and M. novaezelandiae consumed more phacelia pollen than that of buckwheat in the field. These results support the choice of phacelia as an ideal floral resource subsidy in crops for enhanced biological control by these New Zealand species. The need for studying hoverfly movement in a large-scale field experiment was apparent from the field studies, so the next experiment was carried out in a field 450 × 270 m and flies were marked via their ingestion of the pollen of phacelia. The focus was on the proportion of flies having consumed the pollen. Although large quantities of pollen were found in some hoverfly guts, most did not contain phacelia pollen and very few were captured at 50 m from phacelia, compared with numbers at the border of the floral strip. A possible explanation was that hoverflies feed on a large variety of pollen species, reducing the relative attraction of phacelia flowers. Another possibility was that hoverflies dispersed from the phacelia away from the crop. Also, pollen digestion rates are likely to be a factor. Finally, a series of experiments was conducted in the field and laboratory to study hoverfly efficacy through oviposition and larval behaviour. In field experiments, female M. fasciatum and M. novaezelandiae laid more eggs where buckwheat patches were larger; however higher oviposition rates did not lead to improved aphid population suppression. In greenhouse experiments, larvae of E. balteatus could initiate a decline in aphid numbers at the predator: prey ratio 1: 8.3, however this control did not persist. Experiments in the laboratory showed that hoverfly larvae became more active and left the system while aphid numbers declined or numbers of larvae increased. This behaviour was caused by two factors: hunger and avoidance of conspecific larvae. Further experiments showed that the avoidance of conspecifics was caused by mutual interference rather than cannibalism. The results of this work highlight the importance of hoverfly dispersal ability. Given the observations of foraging behaviour of females and mutual interference observed between larvae, and the lack of success in CBC by hoverflies in experiments at the crop scale, it is essential to assess the impact of insect predators and parasitoids at a landscape scale.

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  • Evolutionary bargaining games

    Wright, Julian K. D.

    Working or discussion paper
    Lincoln University

    The simple Nash demand game is analysed in an evolutionary context. The evolutionarily stable strategies (ESS) are characterised in the cases where players have symmetric and asymmetric roles. Introducing stochastic effects we show conditions under which the set of Nash equilibria converges to the Nash bargaining solution as the noise becomes negligible. Two evolutionary models are given for which these conditions are satisfied. In each case above the simulated limit outcome of the replicator selection dynamics is given for a range of parameter values. Both approaches give evolutionary support for the Nash bargaining solution.

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  • Papers presented at the New Zealand Branch, Australian Agricultural Economics Society Conference, Blenheim, July 1988

    Agribusiness and Economics Research Unit

    Working or discussion paper
    Lincoln University

    The themes for the 1986 Conference of the New Zealand Branch of the Australian Agricultural Economics Society were Trade Policy and the GATT Negotiations, Non-Government Arrangements for Funding Agricultural Research, Adjustment in Agriculture, and International Agribusiness Issues. This discussion paper includes the full text of the following papers: Don Greenfield, Trade policy and the GATT negotiations; Donald MacLaren, On the meaning and measurement of agricultural trade distortions; I.J. Bourke and D. Wije-Wardana, GATT multilateral trade negotiations and forest products trade; Ronnie Horesh and S SriRamaratnam, Technical aspects of trade negotiations; Veronica Jardine, Grant M. Scobie and Gary R. Baker, The incidence of trade policies on agriculture: the case of ecuador; T.D. Heiler, Operating a R & D organisation in the user pay environment; R.A. Richardson, Funding and resource allocation in rural and wool research - An Australian viewpoint; R.W.M. Johnson, Adjustiment in agriculture: agribusiness; D.K. Crump, Adjustment in the wheat and flour industry; John Gibson, Bert Ward & Ralph Lattimore, Structural adjustment in egg price determination; Walter Morre and Ron Sandrey, Adjustiment in the kiwifruit industry; A.J. Pollock, Speech notes for AAES NZ branch conference; Roland Woods, International marketing - prospects for statutory producer marketing organisations; A.C. Zwart , Controlling exports : the role of marketing boards; R.W.M. Johnson, Commodity markets and NZ exports; O. Negendank, Kiwifruit - a case for the international coordination of marketing strategies; Y.S. Chiao, Is the recent sharp drop in fertiliser usage a major concern for pastoral production?; Gus Hooke, Why farmers should worry about the budget balance; Ronnie Horesh, Social policy bonds; Grant M. Scoble and Veronica Jardine, Macroeconomic policy, the real exchange rate and agricultural growth: the case of Ecuador; S. SriRamaratnam The New Zealand live sheep export quota: the potential impact and economic considerations; R.L. St. Hill, Single market disequilibrium models: an introduction and application to agricultural finance in New Zealand.

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  • Capital budgeting and policy evaluation using option pricing theory

    Seed, Peter

    Working or discussion paper
    Lincoln University

    For the past three decades analysts have relied primarily on discounted cash flow (DCF) techniques to evaluate projects and policies where cash flows were spread over time. However, recent developments point to DCF being superseded by techniques incorporating option pricing theory as the preferred project and policy appraisal technique, see Brennan and Schwartz (1985), Trigeorgis and Mason (1987), Myers (1987) and Kensinger (1987). Over the past five years option pricing theory has been applied to a broad range of valuation problems. For example, Bardsley and Cashin (1990) have valued the Australian Wheat Corporation's minimum price scheme. Seed and Anderson (1991a and 1991b) have suggested option pricing methodologies for evaluating New Zealand government primary sector policy, Trigeorgis (1990) has demonstrated how an option pricing approach may be used to value managerial flexibility, while Paddock, Seigle and Smith (1988) and Mason and Baldwin (1988) have described techniques for valuing petroleum leases and energy subsidies, respectively. Not only does this demonstrate the flexibility of the underlying theory, but it also suggests a major change has taken place in the way the rights and obligations attached to cash flows are being valued. However, while the option pricing approach has much appeal for financial theorists and academics, policy makers and officials know little or nothing about the technique. This report attempts to remedy this imbalance by outlining the strengths and weaknesses of option pricing methodologies. The report demonstrates in non technical language that the contingent claims approach may be used to value a wide range of assets, cash flows or policy programmes. However, when people think of options they usually think of options on shares which give holders the right to buy or sell them. This association is largely due to the put option transactions of the entrepreneurs of New Zealand finance in the mid to late 1980s. The recent advent of exchange traded options on ordinary shares has also contributed to options' higher profile. While a share option's actual market price depends on supply and demand for the rights attached to the option, Fisher Black and Myron Scholes, derived a theoretical model which can be used to estimate a fair option price. However, Black and Scholes also suggested their model could be used to value risky debt, shareholders' equity, and even options on options. Most initial research and applications of Black and Scholes' work concentrated on pricing share options. However, it was not long before researchers were applying the underlying theory behind option pricing to a number of other valuation problems which had option like characteristics. Broadly, the new applications were classes of contingent claims. That is, assets whose price is dependant on the price of some other asset or occurrence of some event.

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  • Development of a stochastic solute transport model

    Kulasiri, Don

    Book
    Lincoln University

    This document summarises research in stochastic modelling of contaminant transport in aquifers with the specific objective of developing a model for the aquifers which are being built by Lincoln Ventures Ltd. Prior to and during the term of this contract, a study of mathematical theories and applications of stochastic differential calculus was undertaken in order to formulate numerical models which characterise the flow in heterogeneous porous media. A preliminary model was developed using Mathematica® and computational experiments are being carried out to make further improvements to the model.

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  • On development and comparative study of two Markov models of rainfall in the dry zone of Sri Lanka

    Punyawardena, B. V. R.; Kulasiri, Don

    Book
    Lincoln University

    Being closer to the equator, the most important climatic element for agricultural production in Sri Lanka is rainfall which is erratic and highly unpredictable in nature, especially in the dry zone. This study attempts to model the weekly rainfall climatology of dry zone using Markov processes as the driving mechanism based on the 51 years of past data. The weekly occurrence of rainfall was modelled by two-state first and second order Markov chains while the amount of rainfall on a rainy week was approximated by taking random variates from the best fitted right skewed probability distribution out of Gamma, Weibull, Log-Normal and Exponential distributions. The parameters of the both models namely, elements of transition matrices, and scale and shape parameters of the desired distribution, were determined using weekly data. Both first and second Markov chains performed similarly in terms of modelling weekly rainfall occurrence and amount of rainfall if rain occurred. Use of second order Markov chain did not enhance the representativeness of the simulated data to the observed data in spite of being penalised for its large number of computations. Weekly rainfall data generated with the first-order Markov chain model preserve the statistical and seasonal characteristics that exist in the historical records.

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  • Using Flexi to detect a trend in count and binary longitudinal data

    Young Jim

    Book
    Lincoln University

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  • Further evidence on the consequences of foreign direct investment for the New Zealand economy

    Kawa, Izabela; Fox, Mark A.

    Working or discussion paper
    Lincoln University

    After 1984 the New Zealand economy underwent a radical transformation, moving from, arguably, the most regulated economy in the western world to the world’s freest market economy (Passow, 1992). One aspect of this economic deregulation involved major changes in the area of foreign investment - restrictions in areas such as exchange control, overseas borrowing and access to capital markets were gradually removed. These new, liberal policies and an extensive privatisation program opened up a number of opportunities to overseas investors (OECD, 1993). Subsequently, in the early 1990s, the government declared a further relaxation of policies and introduced an investment promotion program. The political and economic impact of foreign investment in New Zealand has been the subject of intense public debate. Recently Dr Don Brash, Governor of the Reserve Bank of New Zealand, has made arguments in favour of foreign investment, concluding that ‘Almost all foreign investment will be of benefit to New Zealand and New Zealanders’ (Brash, 1995, p.254). Dr Brash asserts that foreign investment provides capital, technology, market knowledge, and market contacts. On the other hand, concerns are raised that foreign investment threatens New Zealand’s sovereignty and results in the exploitation of our markets and resources.

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  • Residual concentrations and persistence of the anticoagulant rodenticides brodifacoum and diphacinone in fauna

    Fisher, P. M.

    Thesis
    Lincoln University

    Brodifacoum is a highly effective anticoagulant rodenticide that presents a secondary hazard to some non-target wildlife. The high acute toxicity of brodifacoum to mammals and birds, and its prolonged persistence in liver predicates secondary risk to predators and scavengers of poisoned rodents. Hence there is a need to improve ability to monitor and predict hazards of brodifacoum to non-targets, and optimise use patterns accordingly. Use of a less persistent anticoagulant rodenticide, diphacinone, is an alternative approach currently under investigation in New Zealand. This thesis describes a series of laboratory and pen studies that address information gaps relevant to the assessment of non-target hazards in continued use of brodifacoum, and of using diphacinone as an alternative. Non-lethal techniques for determining sublethal brodifacoum exposure in birds was investigated in chickens. Elevation of prothrombin time was a less reliable index than residual concentrations in tissues. Samples requiring less invasive procedures, such as dried blood spots or faeces, have potential to detect recent sublethal brodifacoum exposure and refinement of these indices could be useful in proactive monitoring of avian wildlife. Residual brodifacoum in eggs of sublethally-exposed hens raised further questions regarding wider non-target hazard and adverse effects on development of fertile eggs or chicks. A laboratory trial with rats found a positive correlation between residual brodifacoum concentrations in liver and the amount of brodifacoum ingested as bait. An estimated 14-22% of ingested brodifacoum was excreted in rat faeces in the period between ingestion of a lethal dose and death, indicating another potentially significant environmental pathway for brodifacoum transfer. In considering diphacinone as a less persistent alternative rodenticide to brodifacoum, evaluation of residual concentrations and persistence in pig tissues was required to estimate secondary hazard to human consumers and adequate with-holding periods for hunting feral pigs in areas where diphacinone was applied. A pen trial showed that domestic pigs were more susceptible to diphacinone toxicity, and thus primary poisoning risk, than previously estimated. Hepatic half-life of diphacinone in pigs was approximately 14 days, indicating reduced persistence in comparison to brodifacoum and enabling estimates of with-holding periods for hunting feral pigs from areas where diphacinone baits were applied. To investigate potential hazards of diphacinone use to invertebrates a trial using tree weta, a native New Zealand invertebrate, was undertaken. Weta readily ate diphacinone wax block baits with no mortality or weight loss evident, indicating low susceptibility. Residual whole-body diphacinone concentrations did not increase with the amount of diphacinone bait eaten. A simple, deterministic risk assessment suggested that, as a single secondary exposure, the maximum diphacinone concentration measured in weta would present a low risk to non-target birds. Given international recognition of the high secondary hazard and corresponding restrictions on use of brodifacoum, continued availability of brodifacoum to non-licensed users and sustained field applications for possum and rodent control in New Zealand is an exceptional use pattern. New data in this thesis suggest that baiting strategies that minimise the amount of brodifacoum available in the environment are important and regulatory review of some New Zealand brodifacoum applications should address this. In parallel, development of diphacinone as an alternative to brodifacoum should continue, as new data here confirms lower persistence in mammalian liver than brodifacoum, and also indicates low toxicity to invertebrates. However further investigation of multiple-exposure hazard and potential sublethal effects of diphacinone on non-target mammals and birds is warranted before extensive and sustained field applications of diphacinone are undertaken.

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  • A nested logit model of vehicle fuel efficiency and make-model choice

    McCarthy, Patrick S.; Tay, Richard S.

    Working or discussion paper
    Lincoln University

    Using data from a 1989 household survey of new vehicle buyers, this paper develops and estimates a nested logit model of new vehicle demands where the make-models in the lower nest are partitioned by their fuel efficiencies in the upper nest. In comparison with the more restrictive multinomial logit model, the results support a nested structure of vehicle choice. Among the findings, improvements in vehicle size, safety and quality increase a make-model's demand. Females, lower income households, younger consumers, non-white purchasers, and buyers in more densely populated areas exhibit higher demands for more fuel efficient vehicles. The results also indicate that vehicle demands have an approximate unitary elasticity with respect to capital cost and are elastic with respect to operating costs.

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  • Some economic aspects of Conference and non-Conference wool shipping

    Chudleigh, P. D.

    Working or discussion paper
    Lincoln University

    It is suggested that the freight rate that an alternative wool shipping service could offer will influence the Conference rate for wool shipped from New Zealand to Europe. Data are presented showing that wool freight rate increases over the past five years have been less than freight rate increases for dairy products and meat, the possibility that wool freight rates may have been held back due to the threat of an alternative service in the form of bulk carriers is suggested. Freight rates for a hypothetical specialised wool service are estimated and compared with Conference rates. These comparisons show that the Conference rates in 1972 and 1976 were very close to the estimated rates for the specialised service. It is also shown that the estimated rates are sensitive to a number of assumptions regarding the specialised service. It is concluded that alternative systems of shipping wool warrant closer investigation in order for the wool industry to move towards the most efficient system for shipping wool to Europe. Whilst it appears quite feasible for wool to be carried by an alternative service within the context of the current wool marketing system, it is likely that the economics of an alternative service would benefit substantially from changes in various aspects of the wool marketing system. In addition, it is probable that a specialised wool service could be geared closely to the wool industry and would permit change and improvements to be effected more easily than the present liner service where wool is viewed as a general cargo. The proposition that the withdrawal of wool from the current liner service would create higher freight rates for other export cargoes may be true in the short term. It is quite probable that the liner service would adjust in the longer term to the new cargo mix so offsetting the need for higher rates of freight, this is especially so since a withdrawal of wool would reduce the high imbalance, by weight and by volume, of the northbound/southbound trades. Apart from detailed investigations into alternative shipping systems, other fruitful areas for study suggested are; (i) Cross subsidy effects between products of freight rates set by the Conference should be identified so that Government policies on protection/subsidisation can be formulated more rationally. (ii) The requirements of wool importers in Europe should be researched more fully, especially with respect to frequency of service and order delivery times. (iii) Further research and investigations are required into how the withdrawal of wool would affect the overall efficiency of the Conference service. Whether cargoes other than wool are best serviced by a shipping service that includes or excludes wool should be investigated in the national interest.

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  • A comment on fisheries and agricultural trade relationships between New Zealand and Japan

    Kitson, G. W.

    Working or discussion paper
    Lincoln University

    The primary objective of this paper is to assess the validity of New Zealand's negotiating strategies with Japan over the question of improved access for New Zealand's agricultural, forestry and fish products in the Japanese market in return for continued access to fish in New Zealand's economic management zones by Japan. This assessment should be regarded as preliminary in so far as it is based only on a subjective evaluation of the facts which surround the issue. These facts were gathered largely as a result of a visit to Japan in November and December 1977, during which discussions were held with fishing companies, fishing industry organisations, officials representing both New Zealand and Japanese interests, and researchers. In addition a good deal of documentary information was gathered from various sources in Japan. It is probable that further evaluation of this will be made subsequently with the objective both of providing New Zealand negotiators with a more detailed and objective data base for their negotiations than is currently available and to provide New Zealand commercial fishing and trading organisations with information of use in developing their marketing plans and in assessing the validity of these marketing plans. Because the New Zealand approach has been to link fishing relationships with agricultural, especially livestock product, relationships, through the format of its negotiations with Japan, it is necessary to discuss not only Japanese fisheries policies and sensitivities but also the inter-relationships of these to livestock policies and the Japanese food economy. For this reason discussions in Japan were extended to food and agricultural economists and officials and information gathered from these sources.

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  • Board structure of New Zealand listed companies : an international comparative study

    Fox, Mark A.

    Working or discussion paper
    Lincoln University

    Remarkably little is known about the boards of directors of New Zealand companies. The most recent research in this area was conducted by Turner (1985) who examined CEO duality among listed companies for 1984, and Chandler and Henshall (1982) who examined board size, incidence of executive chairmanship and the proportion of outsiders on the boards of listed companies. In section two of this paper, I seek to expand on these earlier studies and, in particular, identity what changes in board structure have subsequently occurred. This analysis should give us a sense of the responsiveness of New Zealand companies to pressures to reform corporate governance and the current state of corporate governance with respect to board structure characteristics. In the terminology of Boyd, Carroll, and Howard (1996), this analysis is micro and descriptive in nature. Micro, because I examine board variables, and descriptive because I am focusing on a single country, New Zealand. The approach taken in section two of this paper is not dissimilar to much previous corporate governance research. As Boyd et al. state, "much prior work has taken a descriptive rather than a comparative or explanatory focus" (1996, p.16). In fact international comparative research on board structure is a neglected area, with Boyd et al. (1996) commenting that: " ... international research on corporate governance appears surprisingly scarce" (p.3); and " ... much remains to be done to understand the function and effectiveness of international boards, and to provide comparisons across nations" (p.16). That international corporate governance research is so scarce it is somewhat surprising, especially when several studies indicate that there are in fact marked differences in board structure between some countries (Dalton, Kesner, and Rechner, 1988; Dalton and Kesner, 1987). As Daily and Dalton (1994) demonstrate, these differences in board structure may have important implications for the performance and, ultimately, the very survival of corporations. Section three this paper examines previous international studies of board structure, making comparisons with the available New Zealand data. Section four of this paper contains a discussion and conclusions.

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