22,925 results for 2000

  • Does cooperation enhance competitiveness? : assessing the impacts of collaborative business relationships

    Ryan, Nicholas Paul (2000)

    Masters thesis
    University of Canterbury Library

    Collaboration among firms is now a ubiquitous phenomenon. Many theoretical and managerial perspectives argue that firms that collaborate will outperform those firms that take independent approaches. This thesis reports the results of a study of New Zealand firms that examines the relationship between firm performance and participation in collaborative relationships. Environmental conditions and a firm's strategic orientation are also considered. Given the prevalence of cooperation, the thesis also investigates why many firms do not collaborate. The results of the moderated regression analysis indicate that there are no performance differences, across any of the performance measures used in the study, between firms involved in collaborative activity and firms that choose to remain independent. There is, however, some evidence suggesting that collaborating firms have higher performance levels than firms that would like to collaborate, but are unable to do so. The results also suggest that a firm's strategic orientation influences performance; customer- and technological-orientation both exhibit a positive association with firm performance. The thesis critically evaluates and tests the widely stated but little-tested argument that interfirm collaboration is usually beneficial.

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  • Antimycobacterial natural products

    Copp, Brent (2003-12)

    Journal article
    The University of Auckland Library

    Covering: 1990???2002

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  • Antiparasitic activity of marine pyridoacridone alkaloids related to the ascididemins

    Copp, Brent; Kayser, O; Brun, R; Kiderlen, AF (2003-06)

    Journal article
    The University of Auckland Library

    A series of pyridoacridone alkaloids, including the marine alkaloid ascididemin were tested in vitro for antiparasitic activity against P. falciparum (K1, NF54), L. donovani, T. cruzi, T. b. rhodesiense and two mammalian cell lines (L6, RAW 264.7). Most compounds showed high antiplasmodial activity, moderate antileishmanial activity against both extra- and intracellular forms, and significant trypanocidal effects against T. cruzi and T. b. brucei. However, when tested against mammalian cell lines, most of the compounds were also toxic for macrophage-like RAW 264.7 cells and skeletal muscle myoblast L6 cells. Correlations between molecular structures and antiparasitic activity are discussed in detail. Specific compounds are illustrated with emphasis on their potential as new antiparasitic drug leads.

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  • Chemical discovery and global gene expression analysis in zebrafish

    Pichler, Franz; Laurenson, S; Williams, Liam; Dodd, A; Copp, Brent; Love, Donald (2003-08)

    Journal article
    The University of Auckland Library

    The zebrafish (Danio rerio) provides an excellent model for studying vertebrate development and human disease because of its ex utero, optically transparent embryogenesis and amenability to in vivo manipulation. The rapid embryonic developmental cycle, large clutch sizes and ease of maintenance at large numbers also add to the appeal of this species. Considerable genomic data has recently become publicly available that is aiding the construction of zebrafish microarrays, thus permitting global gene expression analysis. The zebrafish is also suitable for chemical genomics, in part as a result of the permeability of its embryos to small molecules and consequent avoidance of external confounding maternal effects. Finally, there is increasing characterization and analysis of zebrafish models of human disease. Thus, the zebrafish offers a high-quality, high-throughput bioassay tool for determining the biological effect of small molecules as well as for dissecting biological pathways.

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  • Analysis and Evaluation of Single Piles in Laterally Spreading Soil

    McGann CR (2009)

    Theses / Dissertations
    University of Canterbury Library

    Liquefaction–induced lateral spreading is an important load case for pile–founded bridges and port facilities located in seismically active regions. This work presents a kinematic analysis of the effects of lateral spreading on a single pile embedded in a layered soil profile and discusses the applicability of conventional analysis methods to the lateral spreading problem. A series of three–dimensional finite element models are created and analyzed using the OpenSees finite element analysis platform developed at the Pacific Earthquake Engineering Research (PEER) Center. The developed FEA considers a single pile (modeled using beam elements) embedded in a soil continuum (modeled using brick elements). Beam–Solid contact elements are utilized to define the interface between the pile and soil elements. Three distinct reinforced concrete pile designs are considered in the models. Elastoplastic behavior is considered in both the pile and the soil through the use of fiber sections and a Drucker–Prager constitutive model, respectively. Each individual component in the model is validated through a series of simple analyses, ensuring that the desired behavior is captured. Force density–displacement (p – y) curves are extracted from the finite element models and compared to several conventional methods for establishing these curves. The characteristic parameters used in this comparison are initial stiffness and ultimate resistance. Additional, one–dimensional models are created which utilize the same beam elements and consider the soil response through the use of p – y curves generated using both the FEA results and conventional means. The results for the lateral spreading models show that elastoplastic soil behavior must be considered in order to determine appropriate maximum moment demands for piles. Through the extraction of p – y curves from the 3D models, it is determined that the kinematics of the pile greatly influence the extracted curves. A rigid pile undergoing a uniform displacement with depth is the most suitable method for obtaining sensible p – y curves from the models. It is shown that the methods commonly used to establish the characteristic parameters for p – y curves at large overburden pressure (greater depth) estimate values which are in excess of those returned by the finite element models, especially for large pile diameters. In the one– dimensional models, the extracted p – y curves produce moment–curvature demands in piles which are similar to the results of the three–dimensional simulations, while the conventional curves produce demands which do not correlate well with the 3D modeling effort. It is determined that the conventionally–used methods are most applicable for moderately–sized piles subject to loads applied at or above the ground surface, but misrepresent a deeper event such as lateral spreading.

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  • Distomadines A and B, novel 6-hydroxyquinoline alkaloids from the New Zealand ascidian, Pseudodistoma aureum

    Pearce, Allison; Appleton, David; Babcock, Russell; Copp, Brent (2003-05-12)

    Journal article
    The University of Auckland Library

    Distomadines A and B, novel tetracyclic guanidine-containing 6-hydroxyquinoline alkaloids were isolated from the New Zealand ascidian Pseudodistoma aureum and characterised by interpretation of spectroscopic data and chemical derivatisation. Distomadine A exhibited mild antifungal activity but failed to exhibit any biological activity in a range of antitumour, cytotoxicity, anti-inflammatory, and antimycobacterial tests. The known methyl esters of fatty acids eicosapentaenoic acid (EPA), docosahexaenoic acid and eicosatetraenoic acid were also identified in the extract with EPA methyl ester exhibiting mild cytotoxicity to a non-malignant cell line.

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  • The flow and distribution of community forestry benefits : a case study from Pyuthan District, Nepal

    Gentle, Popular (2000)

    Masters thesis
    University of Canterbury Library

    The study was conducted to evaluate the distribution of benefits from Community Forestry (CF) to three economic and two social strata of four community forest user groups in Pyuthan District, Nepal. The benefits of CF were compared in terms of forests products' availability, income and employment generation, and contribution to farming system among the socioeconomic strata of the population. The study compares users' perceptions of availability and reported consumption of forest products now and before CF. The participation and perception of users in decision-making and benefit-sharing system has been assessed in respect to economic and social status of the respondents. Economic stratification of user households into poor, medium and rich was based upon participatory wealth ranking. Social stratification was based on castes; the lower or untouchable castes (so-called) were categorized as a disadvantaged group (DAG) and others as a non-disadvantaged group (NDAG). Both formal and informal research methods (face-to-face questionnaire survey, focus group discussions, observation and committee meetings supported by PRA tools like mapping, ranking and discussions) were applied for information collection. Both perceptions of the majority of the respondents and the data reported by the informants showed the greater scarcity of forest products after CF. Greater scarcity was observed for poor and DAG respondents than for richer and NDAG respondents. Following the scarcity of forest products, the poor and DAG lost more livestock and nutrients to their farmlands. The income and employment opportunities were found very low in comparison to the costs for forest management, forest products, and the opportunity costs of participating in meetings and assemblies. The research concluded that the present practice of CF in the research area is less favorable to poor and DAG than wealthier and NDAG households. In spite of aims to provide forest products in a sustainable and equitable basis, poor and DAG households lost more from the switch to CF. Thus, the present practice of CF is widening the gap between poor and wealthier and DAG and NDAG households, rather than contributing to poverty alleviation as intended by policy. Key words: community forestry, equity, Nepal, poor, disadvantaged group, common property resources.

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  • Efficient Algorithms for the Maximum Subarray Problem by Distance Matrix Multiplication

    Takaoka, Tadao (2002)


    University of Canterbury Library

    We design an efficient algorithm that maximizes the sum of array elements of a subarray of a two-dimensional array. The solution can be used to find the most promising array portion that correlates two parameters involved in data, such as ages and income for the amount of sales per some period. The previous subcubic time algorithm is simplified, and the time complexity is improved for the worst case. We also give a more practical algorithm whose expected time is better than the worst case time.

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  • Towards scalable interfaces using spatial cues for document management

    Edwards, Eddie (2001)


    University of Canterbury Library

    Document management is an unavoidable task. Previous research evaluated the effect of building document management systems exploiting spatial memory. It was proven that spatial memory enhances retrieval tasks for systems dealing with a small number of data items. We investigate the effect of spatial cues with scalable systems. We present EDM (Enhanced Data Mountain), a scalable picture management system based on the Data Mountain by Robertson, Tesle, Tversky & Mullet (1991). Our system exploits the use of spatial cues and spatial memory in retrieving images. This report explains the design methodology behind EDM, in addition to an evaluation that compares EDM with Microsoft’s My Pictures (MP) system for managing pictures. Results show that our subjects were faster at retrieving pictures in the display when using the MP interface, but not significantly so. As expected, the more time subjects spent browsing through the picture groups, the faster they became at retrieval. Subjective satisfaction rating showed an overall preference favouring the MP system over the EDM system. A conclusive statement can not be made regarding the exploitation of spatial memory in scalable systems.

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  • Forces of Nature

    Creek, Alan (2001)


    University of Canterbury Library

    Many systems in the modern world are readily represented as graphs; with nodes representing objects within the system, and edges the relationships between them. The effectiveness of visualisations of complex systems is often dependent on the layout of their graphs; a good layout can provide ready understanding of complexity, while a poor layout does nothing to aid comprehension and can even obscure information. We examine the use of force directed placement (FDP) as an algorithm for automatically laying out connected graphs and introduce ANGLE, a software tool for experimentation with graph layout. FDP assigns properties to nodes and edges analogous with real world objects; principally treating edges as springs and nodes as bodies that are mutually repellent. Iterating over the graph and positioning the nodes according to the notional forces upon them provides a means to arrive at a layout. Previous work has focused primarily on two dimensional layouts with various force models. We tackle the extension into three dimensions and propose a new force model that produces a more reliable quality of layout in a shorter time than earlier models. In addition we look at the problem of terminating layout algorithms at an appropriate time, and examine several means of terminating algorithms when a suitable end result has been achieved.

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  • Music Selection for Internet Radio

    Weiss, Alex (2000)


    University of Canterbury Library

    Music. Radio. The internet. Three very interesting fields which are linked in this project on internet radio stations. A comparative study of existing radio stations is performed. Weaknesses and problems in current internet radio stations, as exposed by the comparative study, are identified. We outline the general problems observed. In particular, focus is placed on automatic music selection. Our approach is based on the notions of music genre, popularity, repetition, catalogue coverage, style continuity and “music programme” generation. A simple internet radio station has already been implemented. The station serves as a platform to test our algorithms.

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  • Mobile Phone Text Entry

    Butts, Lee (2001)


    University of Canterbury Library

    The rapid growth of Short Message Service (SMS) text messaging has meant that a fast and efficient text input method is a very important aspect of a mobile phone interface. The best way to test a new method is an empirical evaluation, but this is a time consuming and complex task. An alternative would be to predict the performance of a new method using a prediction model. Previous prediction models and evaluations of current text entry methods are discussed. The previous models have been shown to be highly inaccurate. A new prediction technique is presented that uses pilot study data and text analysis instead of the complex mathematical formulas of previous techniques. Predictions for the multi-press with next and T9 input methods are compared to the actual performance results of an empirical evaluation. The empirical evaluation also compares the performance of the newer T9 system to that of the more common multi-press method. T9 was significantly faster when entering sentences containing only dictionary words. However, the two methods were not significantly different when entering a mix of sentences that contained dictionary and non-dictionary words. As T9 remembers non-dictionary words that a user enters, it was concluded that T9 was the better method. Subjective data re- flected this with 60% of subjects stating that they preferred T9 over multi-press. The prediction technique was found to be too inaccurate to be useful to interface designers. The main failing of this and previous techniques appears to be the inability to accurately predict the mental preparation factor of the text entry actions. Further work to develop a method to calculate such values is needed.

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  • Medium access control protocols for WDM optical networks

    Mollard, Robert (2001)


    University of Canterbury Library

    Wavelength-division multiplexing (WDM) has emerged as the most popular technology for utilising the huge bandwidth of optical fibre. This paper surveys medium access control protocols for the star, bus and ring WDM network topologies. The performance of two recently developed protocols, Pipelining Cyclic Scheduling Algorithm (PCSA) and Reservation/ACK/Transmission Protocol (RATP), is evaluated by stochastic simulation. It was found that RATP’s performance (measured by throughput and delay) degrades sharply with the increase in network size, making it impractical for use in metropolitan- or wide-area networks. PCSA does not suffer from this restriction, and can realise a throughput of 1. It also delivers short average packet delays, especially under light to moderate system loads.

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  • The Reverse Problem of Range Query.

    Takaoka, Tadao (2002)


    University of Canterbury Library

    We dcsign an efficient algorithm for the problem of the two-dimensional range query. In the range query problem, we specify a range of a rectangular shape in a given (n, n) array, and munt the number of points in the range. If the points have weights, we compute the sum of the weights in the range. In the problem, we give a value v and find a range whcxe sum Clluals the value. time for our algorithms is O(n310gn). We also give an algorithm with O(vn2 log2n) time. This is fast for a small v. We briefly mmpare our problem with the maximum subarray problem where we obtain a subarray that maximizes the sum. We dcsign an efficient algorithm for the problem of the two-dimensional range query. In the range query problem, we specify a range of a rectangular shape in a given (n, n) array, and munt the number of points in the range. If the points have weights, we compute the sum of the weights in the range. In the problem, we give a value v and find a range whcxe sum Clluals the value. time for our algorithms is O(n310gn). We also give an algorithm with O(vn2 log2n) time. This is fast for a small v. We briefly mmpare our problem with the maximum subarray problem where we obtain a subarray that maximizes the sum.

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  • Kottamide E, the first example of a natural product bearing the amino acid 4-amino-1,2-dithiolane-4-carboxylic acid (Adt)

    Appleton, David; Copp, Brent (2003-12-08)

    Journal article
    The University of Auckland Library

    Kottamide E, a novel alkaloid containing dibrominated indole enamide, oxalic acid diamide and 4-amino-1,2-dithiolane-4-carboxamide moieties, has been isolated from the New Zealand ascidian Pycnoclavella kottae. Characterisation was achieved by interpretation of spectroscopic data.

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  • 1,3-dimethyl-8-oxoisoguanine, a new purine from the New Zealand ascidian Pseudodistoma Cereum

    Appleton, David; Page, MJ; Lambert, G; Copp, Brent (2004-02)

    Journal article
    The University of Auckland Library

    A new purine, 1,3-dimethyl-8-oxoisoguanine (2) was isolated from the New Zealand ascidian Pseudodistoma cereum. The structure of 2 was elucidated by the use of standard spectroscopic techniques, including natural abundance H-1-N-15 2D NMR.

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  • AK37: the first pyridoacridine described capable of stabilizing the topoisomerase I cleavable complex

    Marshall, KM; Holden, JA; Koller, A; Kashman, Y; Copp, Brent; Barrows, LR (2004-10)

    Journal article
    The University of Auckland Library

    Pyridoacridines are marine natural products that contain planar structures. Almost all are cytotoxic and capable of DNA intercalation. Several pyridoacridines have demonstrated anti-cancer activity, being able to generate reactive oxygen species or to inhibit topoisomerase (Topo) II. Synthetic pyridoacridines were characterized and compared to other pyridoacridines as well as the Topo-inhibiting drugs (etoposide, 9-aminocamptothecin and wakayin) in a series of in vitro enzyme systems. We found AK37 was able to stabilize a DNA???Topo I cleavable complex, but not a DNA???Topo II cleavable complex. To our knowledge, this is the first report of a DNA???Topo I cleavable complex stabilizing pyridoacridine. Structure comparison studies demonstrated that this activity was lost when an extra ???F??? ring was added, but activity was not affected when the ???D??? ring was removed. AK37 inhibited the catalytic activity of both human Topo I and II.

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  • Marine natural products

    Blunt, JW; Copp, Brent; Munro, MHG; Northcote, PT; Prinsep, MR (2003-02)

    Journal article
    The University of Auckland Library

    This review covers the literature published in 2001 for marine natural products, with 497 citations (373 for the period January to December 2001) and includes 793 compounds isolated from marine microorganisms and phytoplankton, green algae, brown algae, red algae, sponges, coelenterates, bryozoans, molluscs, tunicates and echinoderms. The emphasis is on new compounds and new stereochemical assignments (683 for 2001), together with relevant biological activities, source organisms and country of origin. Syntheses that confirm or revise structures or stereochemistries have been included (95), including any first total synthesis of a marine natural product.

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  • Mechanism of ascididemin-induced cytotoxicity

    Matsumoto, SS; Biggs, J; Copp, Brent; Holden, JA; Barrows, LR (2003-02)

    Journal article
    The University of Auckland Library

    Some marine animals are rich sources of unique polycyclic aromatic alkaloids that are cytotoxic against tumor cell lines and effective in mouse tumor xenograft models. Ascididemin is a pyridoacridine alkaloid originally derived from a Didemnum sp. tunicate. It has potent cytotoxicity against tumor cells in vitro and in vivo. Preclinical screening at NCI revealed the antineoplastic activities of ascididemin and a synthetic analogue 48. Ascididemin has been reported to inhibit topoisomerase II and induce topoisomerase II-mediated DNA cleavage. This study, however, focuses on the unique ability of ascididemin and two synthetic analogues (48 and 109) to cleave DNA in the absence of topoisomerase I or II. An in vitro assay revealed their concentration-dependent ability to cleave DNA and identified dithiothreitol as the sole requirement for maximal activity. On the basis of shared structural features of the three analogues, a double N-bay region and iminoquinone heterocyclic ring, two possible mechanisms of action were hypothesized:??? (1) generation of reactive oxygen species facilitated by metal binding to the common phenanthroline bay region, and (2) production of reactive oxygen species by direct reduction of the iminoquinone moiety. Experimental results supported direct iminoquinone reduction and ROS generation as the mechanism of ascididemin cytotoxicity. Antioxidants protected against DNA cleavage in vitro and protected cultured Chinese hamster ovary cells from toxicity. Additionally, it was shown that cells deficient in the ability to repair reactive oxygen species damage to their DNA were more susceptible to ascididemin and analogues than repair competent cells. Ascididemin-treated cells were also shown to induce oxygen-stress related proteins, further implicating the production of reactive oxygen species as the mechanism of cytotoxicity for these molecules.

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  • Technology for high-throughput screens: the present and future using zebrafish

    Love, Donald; Pichler, Franz; Dodd, Andrew; Copp, Brent; Greenwood, David (2004-12)

    Journal article
    The University of Auckland Library

    The zebrafish is a popular vertebrate model organism with similar organ systems and gene sequences to humans. Zebrafish embryos are optically transparent enabling organ visualisation, which can be complemented with gene expression analysis at the transcript and protein levels. Furthermore, zebrafish can be treated with small molecules and drugs in a microtitre plate format for high-throughput analysis and for the identification and validation of drugs. High-throughput methodologies for use in zebrafish include phenotype-based visualisation, transcript studies using low-density DNA microarrays and proteomic analysis. These technologies offer significant whole-organism biological value in the drug discovery and drug development pipeline.

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