Higher Degree Theses

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Synthesis and kinetics of isomerisation of 2',6'-dihydroxychalcones
(The University of Waikato, 1987) Miles, Christopher O.; Main, Lyndsay
The first-order rate constant, kₒbₛ, for the chalcone - flavanone isomerisation has been determined over the pH range 0-14 in water (μ = 1.0 mol 1⁻¹ with KC1) at 30°C for the following 2' ,6'-dihydroxychalcones: 2' ,6'-dihydroxychalcone (34); 2' ,6'-dihydroxy-4-methoxychalcone (38); 2' ,6'-dihydroxy-3,4-dimethoxychalcone (40); 2' ,6'-dihydroxy-3,4,5-trimethoxychalcone (42); 2' ,6'-dihydroxy-2,4,6-trimethoxychalcone (44); 4-chloro-2' ,6'-dihydroxychalcone (46); 2' ,6'-dihydroxy- 4,4'-dimethoxychalcone (32); 2' ,6'-dihydroxy-3,4,4'-trimethoxychalcone (36); and 2' ,4,6'-trihydroxy-4'-rhamnoglucosyloxychalcone (naringin-chalcone) (48). The pH-rate profiles have been analysed in terms of contributions to cyclisation and ring opening of the various ionised chalcone and flavanone species, and individual rate and equilibrium constants for all the contributing reactions have been determined. Rate measurements with D₂O as the solvent (for 32, 34, 36, 38, 40, 42, 44, 46) revealed a large (presumably primary) hydrogen kinetic isotope effect for one of the contributing reactions, the cyclisation of the chalcone mono-anion. Enthalpies and entropies of activation for the mono-anion cyclisation have also been determined for chalcones 34, 36, 38, 42, 44, and 46. ¹H n.m.r. studies of the product from the cyclisation of the mono-anion in D₂O for two chalcones (34, 38) showed little preference in protonation at the 3-position of the flavanone. Mass spectrometry allowed measurement of the preference for protonation over deuteriation at the 3-position of the flavanone during cyclisation of the mono-anions of 32 and 38, under kinetically-controlled conditions in H₂O - D₂O mixtures. The data obtained were not in accord with the those from kinetic isotope effect measurements. The above results were considered in terms of possible mechanisms for the various reactions involved in the isomerisation. Factors contributing to the specially high rate of cyclisation of 2' ,6'-dihydroxychalcones as compared to simple 2'-hydroxychalcones, and to the high stability of the 5-hydroxyflavanones as compared to simple flavanones (relative to their isomeric chalcones) were also considered. The low stability of the 2' ,6'-dihydroxychalcones, compared to the 2'-hydroxychalcones (relative to their flavanones) was found to be due to a highly reactive mono-anion form combined with a lower first pKₐ, and a greatly reduced susceptibility of the flavanone anions to base-catalysed ring opening. By utilising the above kinetic results, new and improved syntheses of 2' ,6'-dihydroxychalcones have been developed in the face of what are shown to be unreliable literature reports. The following compounds have been synthesised and characterised for the first time: (32); (34); (36); (38); 5-hydroxy-4' -methoxyflavanone (39); (40); 5-hydroxy-3' ,4'-dimethoxyflavanone (41); (42); 5-hydroxy-3' ,4' ,5'-trimethoxyflavanone (43); (44); 5-hydroxy-2' ,4' ,6'-trimethoxyflavanone (45); (46); 5-hydroxy-4'-chloroflavanone (47): 6-benzyl-7-benzyloxy-5-hydroxyflavanone (68); 6-benzyl-5,7-dihydroxyflavanone (69); 2 '-hydroxy-6 '-tetrahydropyrany loxy-3, 4, 5-trimethoxychalcone (70); 3'-benzyl-4' ,6'-dibenzyloxy-2'-hydroxychalcone (72); 2' ,3,4' ,6'-tetrahydroxy- 4-methoxychalcone (86); 2'-hydroxy-4' ,6'-dimethoxy-3'-methylchalcone (93). Two new routes to 2' ,6'-dihydroxychalcones were developed. The first involved base-catalysed condensation of acetophenones and benzaldehydes with free phenolic groups protected as their tetrahydro-pyranyl ethers, followed by deprotection at pH 2. The second involved reaction of flavanones with chlorosilanes, in the presence of 1,8-diazabicyclo[5.4.0]undec-7-ene, in which ring opening of the O-silylated flavanone was immediately followed by silylation of the resultant phenolate oxygen, thereby preventing recyclisation. The crystal structures of 5-hydroxy-4' ,7-dimethoxyflavanone (33) and 2' ,6'-dihydroxy-2,4,6-trimethoxychalcone (44) were determined by X-ray crystallography, 44 being the first 2' ,6'-dihydroxychalcone for which a crystal structure has been obtained. A computer programme was developed for the analysis of pH-rate data for 2'-hydroxy- and 2', 6'-dihydroxy-chalcones, but which is suitable for the analysis of pH-rate data for most mono- or di-acids in which the contributing reactions are (pseudo) first-order. The programme can also include second-order H⁺-catalysed reaction of the di-acid, and one second-order OH⁻-catalysed reaction, and calculates the concentrations of the various ionised species present on the basis that the two pKₐ values may not be well-separated. This programme has been used to successfully analyse the 2' ,4'-dihydroxychalcone - 7-hydroxyflavanone pH-rate profile previously reported, but not analysed, in the same way as for the 2' ,6'-dihydroxychalcones.
X-ray beam modelling in radiotherapy: the effect of lung inhomogeneities
(The University of Waikato, 1990) Metcalfe, Peter Edwin; Round, W. Howell
A lung phantom consisting of epoxy resin based analogs is developed in-house and a quality assurance method, which compares experimental CT numbers with theoretical CT numbers calculated from electronic cross sections, is described. Currently used photon beam inhomogeneity correction models and their inadequacies are discussed. The methods studied include Batho and Equivalent Tissue-Air-Ratio corrections. For a 10 MV high energy photon beam the mean difference in central axis depth dose in the lung phantom for these methods is 8.8% and 3.5%, respectively (for a 5 x 5 cm field). The differences in the beam profiles at an off-axis distance of 5 cm is 12.6% for both methods (for a 10 x 10 cm field). A unified three-dimensional superposition approach to dose calculations used in treatment planning of a polyenergetic 10 MV photon beam in radiotherapy is developed. This radiotherapy X-ray beam computation method involves an electron gamma shower (EGS) Monte Carlo generated surface polyenergetic dose spread array (PDSA), which describes the energy spread from a point interaction source. This is superposed with the relative reduction in polyenergetic total energy released per unit mass (TERMA) as the beam traverses tissue. By comparing primary PDSAs produced at different radiological depths, the effect of beam hardening on the PDSA has been quantified. Calculations show the mean electron range due to the surface 10 MV primary PDSA is 6.67 mm and the mean electron range of the beam hardened primary PDSA is 8.24 mm. In comparison a 3 MV primary monoenergetic dose spread array (MDSA) has a much smaller mean electron range of 4.81 mm. The effect of using a beam hardened PDSA for superposition is also studied. The mean percentage difference between depth dose curves obtained using superposition of a surface and a beam hardened PDSA is only 0.1 %. The mean percentage difference from experimental data for these superposition curves is 1.2% down to 20 cm in a homogeneous phantom. The superposition process is shown to be forgiving to spectral differences in the PDSA but sensitive to spectral changes in the TERMA. A method of scaling PDSAs to account for lung inhomogeneities is introduced which shows good agreement with experimental and Monte Carlo results in the lung phantom. The mean difference in central axis depth dose in the lung phantom for this method is 2.0% for a 5 x 5 cm field. The differences in lung for the beam profile at an off-axis distance of 5 cm is 4.3% for a 10 x 10 cm field.
The effect of voice input on information exchange in computer supported asynchronous group communication
(The University of Waikato, 1991) McQueen, Robert J.; Graham, Ian
Computer support for group communication in the business environment is examined. Study of group activities in videotaped business meetings identified information exchange as the most frequent communication task. Existing computer supported cooperative work (CSCW) systems for group communication are typically based on keyboard input, and this may limit their utility. A voice input prototype system for asynchronous (time separated transactions) group communication (AGC) with simulated conversion to text was developed and tested to determine if advantages over conventional keyboard input computer conferencing existed, and whether this method would have any effect on the information exchange task. An experiment utilizing 12 groups of 5 subjects compared the voice input prototype to an existing keyboard input computer conferencing system for an information exchange task, and over all test subjects, voice input resulted in an increase of the number of words contributed by 151 % and an increase in the information facts disclosed by 38%. For test subjects holding a high proportion of available facts, voice input resulted in increases of 204% in words and 39% for facts. Effective input speed was 150 words per minute for voice input. These results imply that for future asynchronous group communication systems supporting information exchange, incorporation of voice input capability, coupled with large vocabulary, connected word, speaker independent speech recognition should be considered.
The development of secondary education in New Zealand from 1935 to 1970
(The University of Waikato, 1989) Marshall, George Nairn; McLaren, Ian
This study traces the evolution of secondary education in New Zealand from 1935 to 1970, with special reference to questions of curriculum and control. Within the framework of contemporary social, political, and economic developments, it describes the transformation of a system comprising sixty-five schools offering a restricted, specialised curriculum to a mainly selected and limited clientele into one with 210 multilateral schools each catering for an entire age-range of pupils. Data were obtained from official documents and reports, journals, school histories and magazines, newspapers, and other published sources; from unpublished material, especially university theses; from interviews with prominent educationists of the period; and from personal observation and experience. Except for some reference to the Maori denominational boarding schools, the study is confined to state post-primary schools. It includes an examination of the literature related to the topic, and puts forward some theoretical considerations. In 1936, the newly-elected Labour Government set about promoting its ideal of providing equality of educational opportunity for all. However, the post-primary schools were slow to change, even though they were now enrolling increasing numbers of pupils for whom their existing curricula were totally unsuitable. The raising of the school leaving age to fifteen, the introduction of accrediting and the transferring of University Entrance to the sixth form, the release of the Thomas Report, and the inauguration of the new School Certificate all contributed to jolting the post-primary schools from their conservative stance. By the late 40’s, the system was contending with massive roll increases, completely inadequate facilities and resources, and a drastic shortage of teachers. No radical changes in educational policy occurred in the 50’s. The post-primary schools, continued with their struggle to adjust to the post-Thomas era, with its emphasis on catering for individual differences, advancing the social education of pupils, and encouraging greater pupil participation in school affairs. The decade also witnessed the emergence of post-primary teachers as a political force, a revival of the controversy over state aid to private schools, the beginnings of the demise of the technical high school, and the setting up of a Commission on Education in New Zealand to enquire into a wide range of educational issues. As well as ushering in the age of educational technology, the 60’s were characterised by constantly expanding pupil numbers, an increasing need for counselling services in the schools, persistent teacher shortages, the growth of teacher militancy, the rise of ‘pupils’ rights’ movements, the establishing of the Curriculum Development Unit, forward moves in rural education, the general acceptance of the concept of the comprehensive school, and the appearance of the first complete consolidation of the law on education since 1914. These events, trends, and issues provide the raw material of this thesis. Also, at four stages of the period under review, the study examines, in some detail, the policies, practices, and characteristics of the schools themselves, and attempts to present a picture of what it was like to be a principal, a teacher, or a pupil at a New Zealand post-primary school at that time.
Characterization of an extremely thermophilic, anaerobic sulphur-dependent archaebacterium
(The University of Waikato, 1991) Klages, Karin Ursula; Morgan, Hugh W.
The sulphur-dependent archaebacterial isolate ANI was studied in aspects of its ecology, physiology, and enzymology. Organisms closely resembling isolate ANI were enriched from New Zealand hot pools within a temperature range of 55-91°C and a pH range of 5.5- 9.0 and a sodium content above 0.5g/ℓ. The concentration of sodium ions was found to be a third parameter determining the presence or absence of these organisms. Isolate ANI is a neutrophilic, anaerobic extreme thermophile. In the laboratory, growth was observed within a pH range of pH 5.4 to 9.2 and a temperature range between 55 and 85°C. The organism is an obligate heterotroph with a requirement for peptone. In the presence of peptone, several amino acids, α-keto acids, glucose, lactose, casein, and starch stimulate growth. Sodium and sulphur are required for growth. Sodium can be replaced by lithium and sulphur by cystine and glutathione. Sodium is required for utilization of several amino acids and for synthesis of ATP. Presence of a Na⁺ gradient across the cytoplasmic membrane is essential for growth and ATP production. Ionophores affecting the Na⁺ gradient show a strong inhibitory effect, while a protonophore or a K⁺ ionophore exerted virtually no inhibition. In addition to a Na⁺ gradient the existence of either a H⁺ gradient or a membrane potential is required for growth and generation of ATP. The Na⁺ gradient is possibly generated via a Na⁺-translocating ATPase. Utilization of branched-chain amino acids in the presence of sulphur results in production of NH₄, CO₂, H₂, sulphide, and branched-chain fatty acids. When valine is utilized the major fatty acid end product is isobutyrate and with leucine or isoleucine it is isovalerate or 2-methylbutyrate (which could not be distinguished by analytical techniques used here). The metabolic pathway of branched-chain amino acids was investigated. The proposed common metabolic pathway for valine, leucine, and isoleucine involves four steps: deamination and production of the α-keto acid, oxidation of the α-keto acid and production of the acyl-CoA, production of the acyl phosphate from the acyl-CoA, and production of the fatty acid from the acyl phosphate, the latter step being coupled to production of ATP from ADP and inorganic phosphate. The presence of amino acid aminotransferase, α-keto acid oxidoreductase, and fatty acid kinase, which catalyze the first, second and fourth reaction respectively, was demonstrated in crude cell extracts, while the presence of phosphate acyltransferase, catalyzing the third step, was only suggested. Substrate-level phosphorylation is the major, if not the sole means of ATP generation in isolate ANI. Reducing equivalents generated by amino acid oxidation are transferred to a postulated hydrogenase and sulphur reductase respectively and sulphide and H₂ are produced. No inhibitory effect of H₂ could be demonstrated and reduction of sulphur as means for H₂ detoxification does not appear to occur in isolate ANI. Instead, H₂ and sulphide are produced concomitantly during growth. A type II restriction endonuclease of ANI, termed ‘ANi I’, was partially purified and its recognition sequence determined as CTAG. The cut site within the sequence is not known.
Management accounting and the social construction of reality
(The University of Waikato, 1990) Lawrence, Stewart R.; Gilling, Don; Bettison, David; Gilling, Margaret
One of the major problems of researching management accounting practice has been that of research practice. Traditional methods have not been able to yield insights into the richness and diversity of accounting practices in organisational processes. The perspective adopted in this thesis is that accounting practice is a symbolic and value-laden phenomenon that can only be understood in action. One way to understand accounting in action is to undertake a processual, interpretive study of an organisation and its development. The aim is to understand accounting practices where they have been developed and where they are used, as part of the ‘lived experience’ of organisational actors. The organisational setting for this study was that of a medium-sized English book publishing company. The distinctive culture that developed affects and is affected by accounting procedures. The way in which actors called upon and employed accounting procedures in their everyday projects, and the way in which these projects were understood and justified through accounting rationales, are described. The work of the management accountant is influenced both by the particular organisational setting and by the generally accepted constructs through which the professional accountant interprets the world. There is a tension between the rational and the social aspects of accounting practice. Those using accounting systems experience the systems’ inadequacies as purely technical-rational devices. The practice of accounting is actively involved in the regulation, even manipulation, of interpersonal relationships. Accountants have to transcend technique and necessarily become involved in organisational activities as cultural and moral agents. A movement away from a technical conception of management accounting towards a communicative function and understanding is suggested. Such a change in perspective would require an appreciation of the more general interpretive schemes, of which ‘accounting’ is a part, that actors use to understand their reality. It would involve an understanding of the partial nature of the accountants’ perspective and the effect that technical management accounting language and routines have on interpersonal relationships. The next generation of management accountants may regard such understanding as an essential characteristic of ‘practice’. Research using the interpretive approach could play a part in the creation of this new professional perspective.
Estimating and forecasting univariate and multivariate time series using dynamic linear models
(The University of Waikato, 1990) Bolstad, William M.; Foulds, Les R.; Turner, John; Hosking, Roger
This thesis investigates the place of dynamic linear models in time series analysis. These models, which are based on the state space representation of the time series where the dynamic parameters are the state variables, are particularly useful because they are applicable to non-stationary (as well as stationary) time series. In this thesis some forecasting algorithms using dynamic linear models are developed for univariate and multivariate time series, and the effectiveness of these algorithms is investigated. The algorithms are applied to some examples in biometrics and economics. The thesis is based on original research papers published hy the author, which are included as appendices 1-5. Chapter one surveys the field of time series analysis in order to get a broad overview of the subject. There are two main goals in time series analysis: the search for the underlying pattern in the time series, and the prediction of future values of the series. The first leads to the study of the time series in the frequency domain where a harmonic analysis of the time series decomposes it into a sum of sine waves at various frequencies. The second leads to the study of the time series in the time domain. Here the relationship between values a given distance apart is studied for each possible distance, and these relationships are used to predict future values. Chapter two develops the class of second order stationary stochastic processes in the frequency and time domains. The main tool of the frequency domain analysis, the spectral distribution of the process, and the main tool of the time domain analysis, the autocovariance function of the process, are seen to be Fourier transforms of each other. The effect of a time invariant linear filter on a second order stationary stochastic process is determined. It establishes the important results that if a stochastic process is Markovian, it must be the output of a first order linear system excited by Gaussian white noise. The Wiener-Hopf integral equation for the optimal (in terms of minimizing expected squared error) linear filter is developed using the principle of orthogonality. Chapter three introduces the state space representation of a linear dynamic system, develops the Kalman filter by using orthogonal projections, and establishes the recursive equations. Section 3 investigates the efficiency of the dynamic linear model applied to a linearly aggregated time series, and determines the efficiency of estimation using the aggregated time series relative to using the weighted sum of the component model estimators. While it is not surprising that the latter method is more efficient, the exact relative efficiency is developed here for the first time. Chapter four surveys the field of filtering in some non-Gaussian models. While the Kalman filter is still the optimal linear filter in the non-Gaussian case, it may be far from the optimal filter. Chapter five introduces multiprocess dynamic (regression) models to give a filter that is effective for short term forecasting in time series that are subject to abrupt, as well as evolutionary, changes in pattern, and may contain transients (outliers). In Section 3, the multivariate extension of the multiprocess dynamic linear model developed by the author is presented. The forecasting algorithm is used to forecast the quarterly inflation rate in the consumer price index, by using the inflation rates for the six main consumer price subindices, food, housing, household operations, apparel, transportation, and miscellaneous. This method was found to give an improvement over the univariate dynamic linear model forecasts, which in turn are improvements over the naive model forecasts. In Section 4, the biased perturbation multiprocess dynamic linear model developed by the author is presented and used to analyze growth hormone level data in young steers that are subject to dietary stress. The growth hormone level data exhibited the characteristics of pulsatile data, that is exponential decay towards a base level with occasional jumps in level when a pulse of growth hormone is released. The model was found to give an effective method of analyzing pulsatile data that can be implemented in real time. In Section 5, the multiprocess dynamic generalized linear model developed by the author is presented. It is shown to be an effective method for estimating a time varying population proportion. This thesis investigates dynamic linear time series models and has shown their place in the time series analysis framework. The relative efficiency of a dynamic linear model applied to a linearly aggregated time series has been determined. Estimation and forecasting algorithms based on dynamic linear time series models for univariate and multivariate time series have been developed and analyzed. They are effective for time series that contain outliers and exhibit occasional abrupt as well as evolutionary changes in pattern. These algorithms have been applied successfully to non-stationary time series in biology and economics.
The application of parallel processing to radiotherapy dose computation
(The University of Waikato, 1991) Murray, David Campbell; Round, W. Howell; Graham, Ian
Delivery of the correct dose to patients undergoing high-energy x-ray radiotherapy treatment for cancer requires accurate simulation of photon beams. Current algorithms using equivalent depth or tissue-air ratio (TAR) correction techniques fail to accurately model electron transport, and hence show inaccuracy in inhomogeneous regions of the body (especially at high photon energies). Newer techniques such as superposition and Monte Carlo simulation do model these effects, but require a large computational effort. Convolution in Fourier space is adequately fast using even standard microprocessor technology, but this approach lacks the flexibility offered by a density-scalable superposition kernel, available only in real space. However, in order for the real-space superposition algorithm to be clinically useful it is necessary to reduce planning times to acceptable levels. This has been achieved using a multicomputer system based on Inmos T800 transputer modules, where the superposition is calculated using a master/worker network employing synchronous message passing. The calculation is partitioned by decomposing the terma array into a number of command vectors or “grains.” The master task sends a vector to each worker task as it becomes free, and the worker performs the superposition for those interation voxels in the vector, storing the result in a local copy of the dose array. Upon completion of the entire calculation, the worker dose arrays are collected and summed to form the complete dose distribution. This approach has a very small communication overhead and exhibits near-linear speedup with increasing processor number. The superposition algorithm has been incorporated into the GRATIS Treatment Planning System developed at the University of North Carolina. This system, based on the Uɴɪx and X standards, has been installed on a Sun SPARCstation network, with the transputer network attached to the Sbus port of one SPARCstation. The treatment planning system can access the transputers from anywhere in the network, using Sun’s RPC (Remote Procedure Call) standard. Energy deposition kernels required by the superposition algorithm have been produced using the EGS4 Monte Carlo Code System (Stanford Linear Accelerator Center). The user code RTPEDK has been developed to generate spherically symmetric kernels, which are then interpolated by the treatment planning system to form cartesian kernels for use in superposition. Two other user codes, RTPCYL and RTPCART, have been developed to model more general radiotherapy problems based on cylindrical and cartesian scoring geometries, respectively.
The growth and development of American satire: 1630-1895
(The University of Waikato, 1990) Pilditch, Jan; Walker, Marshall; McKim, Anne M.; Arvidson, Ken
The American predilection for ‘soft satire’ is well known. From Benjamin Franklin onwards American satirists have demonstrated a tolerance for human frailty unthinkable in the satires of the great Augustans. This thesis traces the growth and development of American satire from its beginnings in the Colonial period to the end of the nineteenth century. The period encompasses both a change in the understanding of the word ‘satire’, and therefore the type of satire written, and a change in world view which inevitably influenced content. The approach is chronological and historical and follows the growth of American culture as it is manifested in the satires in terms of content, form and language. Early American satires, infused with religious language, imagery, and modes of thought, took their structure from the optimistic American Jeremiad, and asserted the possibility of an ‘ideal America’. This influenced later secular satires which asserted an ‘ideal America’ using a providential frame, forging a link between sacred and secular values. During the course of the American Revolution satirists incorporated essentially secular and humanistic values within the providential frame and continued to assert the possibility of an ‘ideal America’. The effect of the providential frame was twofold. It ensured, in God’s time, an eventual favourable outcome rendering the satires optimistic and therefore corrective rather than destructive. Secondly it allowed for the suppression of realistic detail which could threaten the stability of what was in effect a realistic ideal, an ‘ideal America’. As American millenialism gave way to the humanistic ideals of the enlightenment in American satire the essentially religious view of an ‘ideal America’ gave way to a humane and secular view. The providential frame was dropped and optimism came to depend upon human will. This rendered the value system of the satires unstable. Satire underwent a crisis of authority and Jacksonian democracy was accompanied by works in which the gross materialism of the mob depicted in the attack undermined the democratic ideals the satires asserted. This was accompanied by an increasing Americanization of language, character and content in satirical works which usurped the satiric persona of an authoritative ‘man of letters’ in favour, in some cases, of the man of no letters. The logical dilemma created by notions of a realistic ideal is apparent in satires written immediately before and after the Civil War, so that these satires demonstrate a tendency toward the ‘tragical satire’ seen in the Jacobean period. However, Puritan influence manifested itself elsewhere in American satire in the form of the exemplary figure which, typically journeys like Franklin, along the path to improvement. These figures, like the Providential frame, serve to forge a link between the ideal and therefore absolute, and the real. The figures travel a realistic rather than ideological landscape and in early satires invariably have their share of human faults. They are characterized by an ability to cling to the ideal despite all evidence to the contrary, or by an ability to learn moral and, in the post-Revolutionary satires, essentially Federalist values, including those of the ‘Men of Letters’ who founded the early Republic. In Twain’s Huckleberry Finn, this figure becomes wholly American. The moral growth of Huck in the course of the novel is well known, as are the realistic aspects of his character, but Huck is also intelligent. He demonstrates a facility with language which in earlier satires characterized the satiric persona. It is suggested that as the American absurd hero develops, that figure absorbs the characteristics of the authoritative satiric persona of the ‘man of letters’, creating satire from within, rather than beyond the text - in effect, a democratic satire.
Arginase from Bacillus caldovelox
(The University of Waikato, 1988) Patchett, Mark L.; Daniel, Roy M.; Morgan, Hugh W.
Nine Thermus strains, six thermophilic Bacillus species, six extremely thermophilic archaebacteria and other thermophilic bacteria were cultured in arginine-supplemented media and screened for arginase, arginine deiminase and arginine decarboxylase activity by a reversed-phase liquid chromatography method developed to detect these arginine-catabolizing enzymes in cell-free extracts. Thermus, Bacillus and Sulfolobus strains produced arginase, but arginine deiminase and arginine decarboxylase activities were only detected in two archaebacterial anaerobes and Clostridium thermohydrosulfuricum. Other enzymes of the arginase and arginine deiminase pathways were also present in these bacteria. Inducible arginases (EC 3.5.3.1) were purified from Bacillus caldovelox (DSM 411) and Thermus 4-1A (TRUCC 52) by (NH₄)₂SO₄ and protamine sulphate precipitations, DEAE Sepharose CL-6B ion exchange chromatography, Superose 12 GP-FPLC, Mono Q IE-FPLC and phenyl-Superose HI-FPLC. B. caldovelox arginase has a Mᵣ of ~176000 and a subunit Mᵣ of 32000, suggesting a hexameric subunit structure. It has an isoelectric point of 5.4, a pH optimum for activity of 9 (at 60°C in 0.1M CAPS/NaOH buffer) and requires a divalent cation for activity. The purified enzyme contains 1.2 Mn²⁺ ions and 0.17 Fe²⁺ ions per subunit and is activated ~30% by Mn²⁺. The enzyme has a Kₘ for arginine of 3.4mM at pH9 and 25mM at pH7 and hydrolyses L-canavanine at 4.7% and D-arginine and L-homoarginine at <1% of the rate seen for L-arginine. It is competitively inhibited by L-ornithine with a Kᵢ of 0.55mM at pH9 and 4.4mM at pH7 and has an E, of 46.3kJ/mole at pH9. The B. caldovelox arginase is thermostable with a half life of 105min at 95°C at pH7 in the presence of 0.5mM Mn²⁺ and 25mM aspartic acid. Mn²⁺ and chelating agents or proteins have a synergistic stabilizing effect and it is suggested that an excessive [Mn²⁺] causes inactivation in the absence of a chelating agent. The apoenzyme, prepared by chelation of metal ions at pH7 at 60°C or by incubation at pH4.4 at 20°C, retains its native oligomeric structure but is dissociated into subunits at pH2.5 at 20°C. The subunits reassociate at pH9.5 at 20°C in the absence of Mn²⁺ to form the native oligomer. The Thermus 4-1A arginase has a Mᵣ of ~167000 and a subunit Mᵣ of 33000. It has an isoelectric point of 5.1, a pH optimum of 9.3-9.8 and is activated by V0²⁺, Mn²⁺, Ni²⁺ and Cd²⁺ and less strongly by Co²⁺, Fe²⁺, Mo(III) and Mg²⁺. The purified enzyme contains 0.33 Mn²⁺ ions and 0.1 Fe²⁺ ions per subunit and has an Eₐ of 30.2kJ/mole at pH9.
Studies on sulfate-reducing bacteria which degrade fatty acids and on an obligately anaerobic agarolytic bacterium
(The University of Waikato, 1989) Rees, Gavin Nigel; Harfoot, C.G.; Morgan, Hugh W.
Five methods were used to isolate sulfate-reducing bacteria using palmitate as the enrichment substrate. (1) Standard enrichment procedures gave rise to pure cultures of Desulfovibrio sapovorans. (2) In enrichments which involved the continual transfer of sediment throughout the isolation, two rod-shaped strains were isolated in pure culture and designated strains HoPal and AmPal. These latter strains had a number of characteristics similar to D. sapovorans, but also varied from the general description by a number of characteristics. Determination of their DNA base composition is required for confirmation of their identification. (3) When pasteurized sediment was used in the enrichments with palmitate as the electron donor, a strain of Desulfotomaculum sapomendens was isolated. (4) When enrichments were carried out at 13°C, a sulfate-reducing bacterium was enriched and purified. This bacterium was identified as Desulfobacterium species. (5) A series of enrichments were carried out whereby an increasing dilution of mud was used as the source material. Tubes with mud from the lower dilutions gave rise to typical Desulfovibrio sapovorans. However, mud used at higher dilutions gave rise to Desulfobacterium species, suggesting that these organisms may be present in higher numbers. Enrichments were carried out using branched-chain fatty acids as the electron donor. Freshwater enrichments with isobutyrate and 2-methyl butyrate gave rise to Desulfotomaculum acetoxidans and Desulfovibrio sapovorans, designated Amib and Am2mb respectively. Estuarine enrichments with isobutyrate and 2-methylbutyrate gave rise to Desulfobacterium vacuolatum, designated Okib and a Desulfosarcina species designated Ok2mb. Enrichments from both freshwater and estuarine sources using isovalerate grew very slowly and were not purified in this study. Studies on the physiology of strain Okib showed it was able to oxidize a range of amino acids and keto acids including proline, branched-chain amino acids, 5-aminovalerate and keto isocaproate. It neither fermented amino acids nor carried out Stickland reactions with pairs of amino acids. During the course of isolating the sulfate-reducing bacteria in this study, an obligately anaerobic agarolytic bacterium was enriched in association with a Desulfovibrio species. The agarolytic bacterium was obtained in pure culture and designated 16AV. This is the first account of the degradation of agar by an obligate anaerobe. Strain 16AV grew only on agar, agarose, galactose and cellobiose producing ethanol, acetate, H₂ and CO₂. Strain 16AV probably represents a new species of the genus Acetivibrio.
Schooling for work in New Zealand: a qualitative study of three high schools
(The University of Waikato, 1987) Sultana, Ronald G.; Wadsworth, Ted; Ramsay, Peter
This ethnographic study set out to discover the messages given to students about work within three high schools in a provincial city of New Zealand. Attention was given to overt and covert messages, and to those messages embedded in the structure of schooling itself. The research also ascertained which of these messages students received, and which of them they accepted and contested. A number of variables which influenced both the transmission and the reception of messages were noted. With regard to teachers, these variables included their ethnicity, their personal ideology, and their group ideology as represented by the ethos of their school. With regard to students, variables included their class location, their gender and ethnicity. A confluence of these factors was observed to determine the nature of educational experiences students underwent at school, and the kinds of messages they received - both overtly and covertly - from teachers. This study contributes to the debate within the “new” sociology of education in that it focuses on the relationship between schooling and the established order in society. The data collected show that more often than not, school structures (form), the curriculum (content) and classroom processes (pedagogy) function to serve the interests of the social order, and specifically to satisfy the needs of industry rather than those of democracy. In various ways, the messages given by teachers and schools are shown to belong to the sphere of teaching for work rather than about work. The difference lies in an education which teaches critically about societal structures with the hope of eventually transforming them into more equitable ones, and an education whose main concern is to reproduce citizens who fit the established structures. While teachers are described functioning in the latter mode, the contradictions, conflicts and dialectics which were observed are highlighted to show that such reproduction does not take place without contestation - both on the part of teachers and on the part of students. This contestation in itself opens up spaces wherein students and teachers can exercise agency and autonomy to question - and formulate alternatives to - the structure.
The regulation of post-natal growth in sheep through the growth hormone - insulin-like growth factor axis
(The University of Waikato, 1991) Oldham, Jenny M.; Molan, Peter C.; Green, T.G. Allan
The GH-IGF axis is one hormonal system which is considered to control muscle growth. To investigate the factors controlling post-natal growth of skeletal muscle in lambs, methods of histological autoradiography were developed in the experiments presented in this thesis to provide sensitive measurement of hormone binding in vitro to receptors. The techniques were used to measure receptors for GH, IGF1 and IGF2 in skeletal muscle of prepubertal lambs which had undergone treatment with exogenous growth factors and/or degrees of nutritional restriction before slaughter. Plasma concentrations of IGF1 were positively correlated with good nutrition and treatment of animals with exogenous GH. Whether or not the changes in plasma IGF1 concentrations are associated with changes in the binding of IGF1 to skeletal muscle is possibly dependent on the age of the animal, the severity of nutritional restriction and the tissue type in skeletal muscle from which measurements were taken. Binding of IGF1 was demonstrated in both the muscle fibre and connective tissue in lambs of six months old, with an increase of binding in connective tissue associated with fasting. In lambs of eight months old, binding was present only in connective tissue and not regulated by GH treatment or nutritional restriction of animals. Plasma concentrations of IGF2 were not altered with fasting of animals. Binding of IGF2 was restricted in distribution to connective tissue in six month old lambs and also insensitive to fasting. The greatest density of IGF1 and IGF2 binding in skeletal muscle was always observed associated with blood vessels. GH binding in skeletal muscle was not demonstrated. In conclusion, connective tissue appears to be a more sensitive target tissue than muscle fibre through which the IGFs may mediate the effects of changes in nutritional status.
Further studies of group 14- cobalt carbonyl chemistry
(The University of Waikato, 1988) Service, Miranda; Mackay, Kenneth M.
This thesis describes investigations into several areas of group 14-cobalt carbonyl chemistry including substitution of a bridging carbonyl ligand by an R₂GeH₂ species to form a GeCo₂ triangle, reactions of germanium-cobalt carbonyl clusters with transition metal carbonyl anions and the reactions of Et₄NSnCl₃ with group 14-cobalt carbonyl compounds of the form R₃M'Co(CO)₄ (R₃ = Me, ⁿBu, Ph, Cl, Br; M' = Sn, Ge, Si). Further studies of the reaction between MeGeH₃ and Co₂(CO)₈ have led to a new proposal for the reaction scheme. That is: MeGeH₃ + 2Co₂(CO)₈ → MeGeCo₃(CO)₁₁ + HCo(CO)₄ + H₂ + CO Together with the results obtained from a study of the reaction of H₃GeCo(CO)₄ with Co₂(CO)₈, this has allowed the proposal that “In the absence of marked steric effects, where an even number of hydrogen atoms is attached to a germanium hydride species this will react with Co₂(CO)₈ to replace a bridging carbonyl group to form a GeCo₂ triangle with evolution of H₂ and CO; where there is an odd number of attached hydrogen atoms this will react with Co₂(CO)₈ to also give cleavage of the Co-Co bond to yield a GeCo(CO)₄ species and HCo(CO)₄”. It has been found that substitution of both bridging carbonyl groups of GeCo₄(CO)₁₄ by Me₂GeH₂ or MeGeH₃ is possible and the new compounds [Me₂Ge]₂GeCo₄(CO)₁₂ and [MeGeH]₂GeCo₄(CO)₁₂ have been spectroscopically characterised. An X-ray crystal structure determination has been carried out for (Me₂Ge)₂GeCo₄(CO)₁₂ which shows it to comprise of four GeCo₂ triangles connected by Co-Co edges and Ge apices. An analysis of the carbonyl vibrations of [MeGeR]₂GeCo₄(CO)₁₂ (R = Me, H) and GeCo₄(CO)₁₄ has been carried out. Good spectroscopic evidence has been obtained for the formation of (MeGe)₂Co₄(CO)₁₀[Ge(R)Me] (R = Me, H) from the reaction of (MeGe)₂Co₄(CO)₁₁ with Me(R)GeH₂. Similarly, further evidence for the production of [MeGeR]₂Ge₂Co₆(CO)₁₈ from the reaction of Ge₂Co₆(CO)₂₀ with Me(R)GeH₂ has been obtained. The two trigonal pyramidal clusters, [(CO)₄Co]GeC0₃(CO)₉ and MeGeCo₃ (CO)₉, reacted with Me(R)GeH₂ to provide the open-skeleton derivatives [MeGeR]Co₂(CO)₆[GeCo₂(CO)₇] and [MeGeR]Co₂(CO)₆[Ge(Me)Co(CO)₄] respectively. These have been spectroscopically characterised. The thermally initiated ligand substitution reactions of the closo hexanuclear clusters, (RGe)₂Co₄(CO)₁₁ (R = Me, Co(CO)₄), with PPh₃ or P(OEt)₃ resulted in breakdown of the cluster to afford mainly [(R₃P)Co(CO)₃]₂. However, the electron transfer catalysed reaction of (MeGe)₂Co₄(CO)₁₁ with P(OEt)₃ in a 1:1 ratio provided the monosubstituted derivative, (MeGe)₂Co₄(CO)₁₀(POEt)₃, in moderate yields which has been spectroscopically characterised. Similarly, the reaction of (MeGe)₂Co₄(CO)₁₁ with ᵗBuNC at room temperature appeared to yield the monosubstituted derivative (MeGe)₂Co₄(CO)₁₀CNᵗBu. Reaction of [(CO)₄CoGe]₂Co₄(CO)₁₁ with Et₄N[Co(CO)₄] produced the known anionic cluster Et₄N[Ge₂Co₇(CO)₂₁] in comparatively good yields. The same product was obtained from reaction of Ge₂Co₆(CO)₂₀ with Et₄N[Co(CO)₄], however condensation to [(CO)₄CoGe]₂Co₄(CO)₁₁ was required before reaction with the anion takes place. The reactions of Et₄NSnCl₃ with R₃M'Co(CO)₄ (R = Me, ⁿBu, Ph, M' = Sn; R = Ph, M' = Ge; R = Cl, M' = Si) all yielded the known tin-cobalt carbonyl anion, Et₄N[{Cl₂[Co(CO)₄]Sn}₂Co(CO)₃]. Reaction of Et₄NSnCl₃ with Br₃SnCo(CO)₄, however, produced a mixture of anions of the form Et₄N[(BrₓCl₃₋ₓSn)Co(CO)₃(SnClyBr₃₋y)] (x,y = 0-3). This mixture has been characterised by infrared, ¹¹⁹Sn NMR and FAB mass spectroscopy and an X-ray crystal structure determination has been carried out for Et₄N[(Br₂ClSn)₂Co(CO)₃]. Preliminary studies have been carried out for several other related systems.
Physical volcanology, emplacement history and inferred viscosity of two rhyolites
(The University of Waikato, 1989) Stevenson, Richard John; Hodder, Peter; Briggs, Roger M.
Rhyolite lavas have not been observed to erupt in New Zealand. No detailed measurement of the physical volcanological properties of lavas has been undertaken to date. However, the detailed measurement of fabric parameters from lava flow unit profiles, provides an insight into emplacement history, rheological behaviour, and ultimately volcanic hazards of rhyolite lavas. Two contrasting Cenozoic rhyolites were studied: Ben Lomond flow - a calc-alkaline rhyolite flow 3.5 km length of 110 ka age; and a pantelleritic flow sequence of Quaternary age from Mayor Island. The general stratigraphy of a rhyolite flow comprises: finely vesicular pumice; upper obsidian layer; central crystalline rhyolite; lower obsidian layer; and a basal breccia. Fabric measurements include density, proportions of primary and secondary voids, void and autoclast aspect ratios, and microlite length. Porosity data provide information on the distribution of volatiles in an emplacing lava, and spherulites on post-emplacement volatile migration. Primary voids are suppressed below 10 m depth. The largest spherulites most commonly occur above the central rhyolite core, suggesting late flow migration of volatiles from a crystallising flow centre. Supportive evidence is: vesiculation of explosion breccia at c.30 m depth; a coincident peak in water content; and subtle trace element variations. Microlites of uniform length formed prior to emplacement. Subsurface evidence (microlite shape) supports an increasing undercooling, and degassing of an originally hydrous magma, collapsing from an inflated foam before emplacing as a viscous flow. Effervescence occurred within the carapace during flow. Isobaric crystallisation within the flow centre, triggered explosion breccia formation just before and after the flow front stopped advancing. Sixteen years elapsed as the flow centre cooled below the glass transition temperature. Late-flow migration of soluble trace elements is consistent with subtle variations in Na₂O, Cl, H₂O and the development of secondary fabrics. Groundwater metasomatism is manifest in pumiceous fabrics. Viscosity, calculated from major element chemistry, temperature, and water content, is 10⁷ poise for the magma (chamber); 10¹² poise (conduit); and 10¹¹ poise for the central flow. Three peralkaline flows from Mayor Island were studied: Panui flow (a lava pond within a tuff ring); Pre-8 ka flow; and the 8 ka flow sheet. No explosion breccia and no significant spherulitisation or lithophysae occur. Carapace sections show ramp structures, anticlines compressed into spines, and synclinal troughs. In contrast to Ben Lomond, more bubbles occur in the upper obsidian layer. A high flow temperature ( ~ 950°C), variations in microlite length throughout the flow profiles and viscous deformation of powdered and block samples (furnace experiments) point to a fluidal rheology. The main differences between pantelleritic and calc-alkaline emplacement models is a spatter-fed emplacement mode, microlite growth and high temperature isobaric crystallisation during flow. Significant variations in Na₂O, La, Ce and Cl support high temperature migration of volatiles associated with the crystallisation of rhyolite. Sodic fluids were more concentrated in Cl and F in fluid lavas containing 2 - 10 times less water than Ben Lomond. Estimated viscosity of Mayor Island lavas is between 10⁷ - 10⁸ poise. Temperature has a significant contribution to the fluidity of the lava allowing a spatter-fed emplacement and rehomogenisation of the spatter as a distally tapering flow sheet. Void aspect ratio and porosity are parameters that best approximate the theoretical viscosity profile, whereas mean microlite length approximates the temperature curve only for the Mayor Island lavas. The calc-alkaline emplacement model was tested on two poorly exposed rhyolitic centres: Pauanui (Miocene age); and the Okataina Volcanic Centre flows (19 ka - 5.5 ka age). Ben Lomond and Mayor Island flows are compared with overseas rhyolites. The range of morphology of rhyolite landforms is primarily dependent on effusive volume and effusion rate. No significant difference occurs in the viscosity of domes, coulees and flows of similar eruptive chemistry and temperature, from the same volcanic centre.
A chemical investigation of some New Zealand honeys
(The University of Waikato, 1989) Tan, Seng To; Wilkins, Alistair L.; Molan, Peter C.
Ether extracts were made from aqueous solutions of various floral types of New Zealand honeys with the use of a continuous liquid/liquid extractor. The components of the extracts were methylated before being separated and identified by gas chromatography and mass spectrometry. When a component could not be identified in this way, bulk extraction of representative unifloral honey samples was carried out and the extractives separated by preparative layer chromatography. The structures of the major components were then elucidated by techniques such as high resolution probe mass spectrometry and one and two dimensional ¹H and ¹³C nuclear magnetic resonance spectroscopy, and on one occasion also by X-ray crystallography. Classes of compounds identified include hydrocarbons, straight chain mono- and dibasic acids, aromatic substances, monoterpenes and degraded carotenoid-like extractives. Compounds reported for the first time in honey include 2,6-dimethyl-6(8)-hydroxy-2-trans-2, 7-octadienoic acid, 3 ,5 ,5-trimethylcyclohex-2-en-1-one, 3 ,5 ,5-trimethylcyclohex-2-ene-1,4- dione, 4-hydroxy-4-(3-oxo-1-butenyl)-3,5,5-trimethylcyclohex-2-en-1-one, 4- (3-oxo-1-butenylidene)-3 ,5 ,5-trimethylcyclohex-2-en-1-one, trans-cis and trans-trans-abscisic acid, 1,4-dihydroxybenzene and 2,6,6-trimethyl-1-(3- oxo-trans-1-butenyl)-cyclohexane-trans-cis-l,2,4-triol. The triol appears to be a new compound. Quantitative analyses of extractable organic substances from a series of white clover type, manuka, ling/heather, thyme, nodding thistle, vipers bugloss, kamahi and willow honeys afforded chromatograms which serve to uniquely characterise the floral sources of the honeys. Correlation was sought between the occurrence of extractable organic substances and the non-peroxide antibacterial activity of honey. Various potential antibacterial components were identified in this way. Quantitative testing of the pure compounds showed that 1,4-dihydroxybenzene probably accounts for all of the non-peroxide antibacterial activity of vipers bugloss honey, and that 4-hydroxy-3,5-dimethoxybenzoic acid and 2-hydroxy-3-phenylpropionic acid account for 0.2-0.35% and 1.6-3.2% respectively of the non-peroxide antibacterial activity in manuka honey.
A study of learned helplessness in school children
(The University of Waikato, 1989) Ukpong, Eno Macaulay; Haigh, Neil; Katterns, Robert; Mitchell, David; van Kraayenoord, Christa
This study grew out of the researcher’s concern about the high rate of school failure and drop-out among students in Nigerian schools. It focussed on the phenomenon of Learned Helplessness, a factor that seemed likely to account for some school learning problems. In the course of the study, instruments and procedures that might be used to identify learned helpless school learners were developed and trialled and an in-depth investigation of their cognitive and emotional life was undertaken. The first phase of the study which focussed on identification issues, involved the trial of four identification procedures - a written description of Learned Helplessness. Learned Helplessness Traits Checklist, an Interview and an Attribution Questionnaire. In the second phase of the study, a case study strategy was adopted to explore the cognitive and emotional life of six Form Two children identified as learned helpless as an outcome of the phase one investigation. The data gathered during the first phase highlighted both strengths and limitations in each of the identification procedures and thus, the need to use several contrastive procedures to ensure accurate identification. The case study data confirmed that the six children exhibited cognitive, motivational and emotional deficits that have been identified in previous studies as facets of Learned Helplessness syndrome. The data also indicated that in a school setting, Learned Helplessness develops over an extended time frame and may wax and wane as classroom conditions change. Important individual differences in some aspects of the children’s helplessness were also revealed. These differences were apparent in the children’s perception of factors responsible for their learning difficulties, their coping strategies, and their emotional responses to some situations that prompted their helplessness. Educational implications that followed from the case study centre on the need for more studies aimed at identifying school factors that might encourage the incidence of Learned Helplessness. Most importantly, teachers, counsellors and others who wish to work effectively with children who appear to have given up on learning should endeavour to gain insights into their inner life and consider the children’s attributions seriously, in order to detect and correct attributions which are unrealistic. An understanding of the children’s views of themselves and factors which account for their learned helplessness may also correct any faulty attributions that others might have made for their learning difficulties. Second, there is also a need to create awareness among educators and classroom teachers about conditions that might precipitate a feeling of helplessness and to suggest diagnostic strategies to help curb the occurrence of the phenomenon. In the final stage of the study it was concluded that learned helpless learners characteristically exhibit behaviours certain overt and covert behaviours which understandably hamper their performance. To obtain a holistic view and understanding of these behaviours requires the use of several contrastive research strategies. Such, the researcher hopes might yield information that could assist in the planning of intervention programmes for learned helpless school learners.
Cloned xylanolytic and cellulolytic enzymes from an extreme thermophile
(The University of Waikato, 1990) Schofield, Linley Rose; Daniel, Roy M.
Heat treatment was a successful purification step for five xylanolytic and cellulolytic enzymes cloned from the extreme thermophile ‘Caldocellum saccharolyticum’ strain Tp8T6.3.3.1. Temperature and length of heat treatment can be altered to give high recovery, or a high degree of purification. Higher purification could be gained by heat treatment at an acidic pH. Various studies showed that further factors, such as protein concentration, were also important. The substrate specificities of the five enzymes were investigated. The β-xylosidase had a very narrow substrate specificity, with high activity only on o- or p-nitrophenyl β-D-xylopyranoside and no activity on xylobiose. It showed some transferase activity. The xylanase had high activity on xylan, releasing xylobiose and some xylotriose. It also hydrolysed carboxymethylcellulose, 4-methylumbelliferyl β-D-cellobioside (MUC) and p-nitrophenyl β-D-cellobioside but could not hydrolyse xylobiose. It showed transferase activity on p-nitrophenyl β-D-xylopyranoside. The β-glucosidase also had broad substrate specificity, with activity on cellobiose and aryl glycosides, but not xylobiose. The carboxymethylcellulase acted as an endoglucanase, with high activity only on carboxymethylcellulose. The MUCase appeared to have two catalytic sites. The N-terminal domain acted as an exoglycobiohydrolase, with high activity on xylan, MUC and p-nitrophenyl β-D-cellobioside, while the C-terminal domain acted as an endoglucanase, with high activity on carboxymethylcellulose. The xylanase was purified and found to have a molecular weight of 42 000 and an isoelectric point of approximately 5.0. It showed optimum activity at pH 5.0 - 7.7 and had an activation energy of 44kJmol⁻¹. The half life at 75°C was 20 minutes in the presence of 0.5mgml⁻¹ bovine serum albumin. The xylanase was stable at room temperature at pH 4.5 - 11.5 in the presence of 0.5mgml⁻¹ bovine serum albumin. Xylose did not appear to inhibit the xylanase, but xylobiose may be inhibitory. The Kₘ for oat spelts xylan was 0.02% (w/v) at pH 6.0. The xylanase had higher activity on oat spelts and sugar cane bagasse xylan than larchwood xylan. The two catalytic residues were predicted to be positioned at the N-terminus of the xylanase. A truncated MUCase containing only one catalytic domain (the exoglycobiohydrolase) was studied. It retained activity on the substrates that the entire protein (containing all domains) hydrolysed. The truncated MUCase had a molecular weight of 84 000. Activities on MUC and Avicel were stable for at least 24 hours at 75°C. The activation energy of the truncated MUCase on MUC was lower (39kJmol⁻¹) than that of the entire protein (55kJmol⁻¹). The two catalytic residues of the exoglycobiohydrolase domain were predicted to be positioned at the N-terminus of the MUCase. The two catalytic residues of the endoglucanase domain, present in the entire protein, were predicted to be in the middle of the C-terminal endoglucanase domain.
How to foster visitors’ environmentally responsible behaviour in nature-based tourism of South Korea
(The University of Waikato, 2026) Lee, Jiwon; Ryan, Chris; Cockburn-Wootten, Cheryl
The COVID-19 pandemic reshaped patterns of mobility, leisure, and tourism, highlighting the importance of nearby green spaces for physical and psychological wellbeing. At the same time, increasing environmental crises underscored the vulnerability of the tourism sector to climate change. Within this context, nature-based tourism (NBT) has gained attention for its potential to promote stress recovery, attentional restoration, and wellbeing, as explained by Attention Restoration Theory and Stress Recovery Theory. These restorative outcomes are also associated with ecological awareness and environmentally responsible behaviour (ERB). However, empirical research examining the relationships among multidimensional visitor experiences, restorative outcomes, environmental attitudes (NEP), and ERB remains limited, particularly in East Asian contexts. South Korea provides a distinctive setting for this inquiry due to its mountainous geography and cultural traditions emphasising harmony with nature. In particular, Seoul’s Dullegil trails, which attract over 1.6 million visitors annually, offer a unique urban nature-based tourism context where natural and urban landscapes coexist. Accordingly, the objectives of this study are: (1) to identify the multidimensional nature of visitor experiences within Korean nature-based tourism settings; (2) to examine how these experiential dimensions relate to restorative outcomes and environmental attitudes; and (3) to investigate how such experiences and outcomes contribute to environmentally responsible behaviour (ERB). Guided by a post-positivist paradigm, this study employs a mixed methods design to capture both generalizable patterns and in-depth insights into visitor experiences. Quantitative data were collected through on-site surveys to examine relationships among key variables, while qualitative data were obtained from semi-structured interviews to explore the meanings behind individual experiences. According to the interview guideline suggested by Castillo-Montoya (2016) interview questions were systematically developed and total 26 participants were recruited through purposive and snowball sampling of visitors to Seoul’s Dullegil trails. Interviews were conducted on-site or nearby between December 2023 and January 2024, lasting 45–60 minutes. Visual prompts, such as photos of hiking routes, were used to encourage rich responses. All interviews were recorded, transcribed in Korean, and translated into English with back-translation to ensure accuracy. For the analysis of qualitative interview, thematic analysis, following Braun and Clarke (2006)’s six-phase framework, identified ten overarching themes and 64 experiential codes, capturing cognitive, emotional, relational, and aesthetic dimensions of trekking. Frequently reported experiences included appreciation of scenery, pleasure and excitement, and stress relief. These qualitative insights informed the development of 57 structured survey items, validated through expert review using the Content Validity Index. A pilot survey with 119 responses confirmed the reliability of all items via PCA, KMO, and Bartlett’s tests, providing a robust foundation for the subsequent quantitative phase. In the quantitative phase, 598 valid survey responses were collected from trekkers on Seoul’s Dullegil trails to test hypotheses developed from the qualitative stage. Exploratory factor analysis confirmed nine experiential dimensions—immersion, therapeutic, achievement, reflective, learning, social interaction, social bonding, unpleasant, and perceived risk—alongside restorative outcomes (RES), environmental attitudes (NEP), and environmentally responsible behaviour (ERB). Structural equation modelling demonstrated robust measurement properties and adequate model fit, explaining substantial variance in RES (R² = 0.617), NEP (R² = 0.328), and ERB (R² = 0.406). Immersive experience emerged as the strongest and most consistent predictor, exerting positive effects on all three outcomes. Therapeutic, achievement, and learning experiences influenced both RES and ERB, while reflective experience predicted only RES. Social bonding was positively associated with RES and ERB, whereas casual interaction had a targeted effect on ERB alone. Perceived risk showed no significant associations, while unpleasant experiences unexpectedly heightened NEP. Among outcome relationships, RES predicted ERB but not NEP, whereas NEP directly predicted ERB, indicating distinct but complementary pathways to responsible behaviour. These findings demonstrate that specific experiential dimensions contribute differently to restorative outcomes and environmentally responsible behaviour. In particular, immersive and therapeutic experiences emerged as important pathways promoting both restoration and pro-environmental engagement, while eco-centric beliefs (NEP) directly influenced environmentally responsible behaviour (ERB). This study advances theory and practice in nature-based tourism by integrating qualitative insights with quantitative modelling. It extends Attention Restoration Theory, Stress Recovery Theory, and Social Exchange Theory by identifying nine experiential dimensions and incorporating embodiment, broaden-and-build, self-determination, social norm, and social capital perspectives. Managerially, findings recommend trail designs that prioritise immersive and therapeutic features, foster social bonding, and enhance exploratory learning to jointly promote restoration and environmentally responsible behaviour. Limitations include the urban, Seoul-specific trekking context, cross-sectional and self-reported data, and limited sensitivity of NEP to short-term experiences. Future research should test generalisability across settings, employ longitudinal/experimental designs, incorporate behavioural observations (e.g., GPS/litter audits), use complementary attitudinal constructs (e.g., identity, place attachment), and examine negative experiences alongside positive ones.
The influence of organisational environmental sustainability on employee outcomes
(The University of Waikato, 2026) Sheeran, Zane; Sutton, Anna; Cooper-Thomas, Helena D.
As two global challenges - climate change and mental health crises - intensify, organisations are increasingly being called to address both environmental sustainability and human well-being. In this thesis, we investigate whether environmental sustainability within organisations can simultaneously support the natural environment and enhance positive human outcomes, specifically, well-being and performance. Grounded in the theories of Person-Organisation fit and Self Determination, we address the overarching question: Can sustainability in organisations enhance the well-being and performance of employees? This thesis consists of four interconnected studies, that each explored key parts of this question using diverse populations and research methods. Study One (N = 292 ) used a cross-sectional design to examine whether university students who perceive their institutions as more environmentally sustainable report higher levels of well-being, and whether this relationship is moderated by their environmental attitudes. Study Two (N = 199) focused on an employee population and assessed how perceived organisational sustainability relates to both employee well-being and job performance using a cross-sectional design. It also tested whether sustainability mediates the relationship between well-being and performance, offering novel insights into the mechanisms linking sustainability and human outcomes. Study Three (N = 628 [T1], 493 [T2]) used network analysis to examine the interconnectedness of sustainability with work-related and employee variables over time. Finally, Study Four (N =72) used a mixed methods intervention-based design with a waitlist control to investigate potential causality, testing whether increasing employees’ perceptions of their workplaces’ sustainability could influence their well-being and performance. The findings indicate that environmental sustainability within organisations is positively related to both well-being and performance. Study One showed students who perceived their institution as more environmentally sustainable reported higher well-being, independent of their personal environmental attitudes. Study Two showed that sustainability and well-being independently predicted job performance, with sustainability adding explanatory value beyond well-being and partially mediating the well-being–performance relationship. Study Three demonstrated stable interconnections between sustainability, well-being, performance, and person–organisation fit over time. Finally, Study Four provided initial evidence for potential causal effects. Combined, these findings have important implications for organisations and their leadership. By authentically embedding sustainability into core workplace strategy and culture, organisations can not only address pressing environmental challenges and reap the related benefits such as increased public image, but also cultivate healthier and higher-performing employees.

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