Does baiting influence the relative composition of the diet of foxes?

The changes in the diet of foxes (Vulpes vulpes) in the Jervis Bay Region was assessed following a long-term baiting program by analysing the composition of fox faecal excreta (scats). In all, 470 fox scats were collected between April and August 2003 from two baited sites, Booderee National Park (BNP) and Beecroft Peninsula, and from two unbaited sites in the southern and northern parts of Jervis Bay National Park (SJBNP and NJBNP respectively). Diet was compared between these sites and mammalian diet was also compared from scats collected before baiting in 1996 and after baiting in 2000 at Beecroft Peninsula and in 2001 at Booderee National Park. In 2003, the most common species consumed by foxes was the common ringtail possum (Pseudocheirus peregrinus), except at unbaited NJBNP, where the swamp wallaby (Wallabia bicolor) was the most frequent dietary item. Significant dietary differences were found between unbaited and baited sites, with the long-nosed bandicoot (Perameles nasuta) and P. peregrinus featuring more in the diet of foxes from the baited sites. Marked increases in the frequency of occurrence of P. peregrinus and P. nasuta in fox scats occurred from before baiting through to after baiting. Relative fox abundance, as indexed by the number of scats collected per kilometre, was lowest in Booderee, followed by Beecroft, then SJBNP, with NJBNP having the highest relative abundance of foxes. We suggest that baiting did affect the diet of foxes on both peninsulas and that the dietary changes across baiting histories were intrinsically related to an increase in abundance in some taxa as a result of relaxed predator pressure following sustained fox control. However, the lack of unbaited control sites over the whole study precludes a definitive conclusion.

Entrepreneurship in Mexico : lessons for stakeholders in New Zealand

A “neighbour” separated by 6,000 km of Pacific, Mexico is by far New Zealand’s largest trading partner in Latin America and its 15th largest overall. With two-way trade worth NZ$584 million in 2002, many Mexicans grow up on New Zealand milk powder and baby formula. Not only is Mexico’s population of 100 million a huge potential economic partner in its own right, through its network of free trade agreements, Mexico has preferential access to 860 million consumers in 32 countries covering sixty percent of the world’s GDP.

Like New Zealand, Mexico is a “New World” country open to new ideas and innovation. Also like New Zealand, Mexico is known internationally for economic reforms that have created two outward-looking, world-trading, and competitive economies. During the last 50 years, the Mexican economy has shifted away from the once dominant sectors of agriculture and mining toward more industrial activities, especially in the major urban centres of Mexico City, Monterrey, Guadalajara, and other regional centres, where entrepreneurs are concentrated. With this shift, a new class of entrepreneurs arose with the support of the government.

One of those regional centres is the State of Sinaloa, with its capital city, Culiacán. Spearheaded by a visionary government and personified by the Secretary of Economic Development, Heriberto Felix Guerra. Secretary Felix is himself restaurant entrepreneur who owns a growing chain of “concept food” restaurants in the region.

It is no accident that when New Zealand Prime Minister Helen Clark visited Mexican President Vicente Fox Quesada on 15 November 2001, one of the topics of conversation was the fact that very day their two countries had been benchmarked as two of the world’s most entrepreneurial countries in the Global Entrepreneurship Monitor 2001 survey.

More germane, both countries have low-aspiration entrepreneurs who generate low levels of wealth and have low potential for growth. Both are dominated by micro-businesses that do not have high-value-added components and are not investment-ready and pre-qualified for risk capita.

This leads to the question, what can New Zealanders learn from the experience of Mexican entrepreneurship?

Assessing the strain experienced by managers and professional Australian footballers using an augmented job strain model

Generic models of job stress, such as the Job Strain Model (JSM), have recently been criticised for focusing on a small number of general work characteristics while ignoring those that are occupation-specific (Sparks & Cooper, 1999). However this criticism is based on limited research that has not examined the relative influence of all three dimensions of the JSM - job demand, job control and social support - and job-specific stressors. The JSM is the most commonly used model underpinning large-scale occupational stress research (Fox, Dwyer, & Ganster, 1993) and is regarded as the most influential model in the research on the psycho-social work environment, stress and disease in recent times (Kristensen, 1995). This thesis addresses the lack of information on the relative influence of the JSM and job-specific stressors by assessing the capacity of an augmented JSM to predict the strain experienced by managers and professional Australian footballers. The augmented JSM consisted of job-specific stressors in addition to the generic components of the model. Managers and professional Australian footballers represent two very different occupational groups. While the day-today roles of a manager include planning, organising, monitoring and controlling (Carroll & Gillen, 1987), the working life of a professional Australian footballer revolves around preparing for and playing football (Shanahan, 1998). It was expected that the large differences in the work undertaken by managers and professional Australian footballers would maximise the opportunities for identifying job-specific stressors and measuring the extent that these vary from one group to the next. The large disparity between managers and professional footballers was also used to assess the cross-occupational versatility of the JSM when it had been augmented by job-specific stressors. This thesis consisted of three major studies. Study One involved a survey of Australian managers, while studies Two and Three focused on professional Australian footballers. The latter group was under-represented in the literature, and as a result of the lack of information on the stressors commonly experienced by this group, an in-depth qualitative study was undertaken in Study Two. The results from Study Two then informed the survey of professional footballers that was conducted in Study Three. Contrary to previous research examining the relative influence of generic and job-specific stressors, the results only provided moderate support for augmenting the JSM with job-specific stressors. Instead of supporting the versatility of the augmented JSM, the overall findings reinforced the broad relevance of the original JSM. Of the four health outcomes measured in Studies One and Three, there was only one - the psychological health of professional Australian footballers - where the proportion of total variance explained by job-specific stressors exceeded 13%. Despite the generally strong performance of the JSM across the two occupational groups, the importance of demand, control and support diminished when examining the less conventional occupation of professional football. The generic model was too narrow to capture the highly specific work characteristics that are important for this occupational group and, as a result, the job-specific stressors explained significantly more of the strain over and above that already provided by the generic model. These findings indicate that when investigating the stressors experienced by conventional occupational groups such as managers, the large amount resources required to identify job-specific stressors are unlikely to be cost-effective. In contrast, the influence of the more situation specific stressors is significantly greater in unconventional occupations and thus the benefits of identifying these non-generic stressors are more likely to outweigh the costs. Studies One and Three identified strong connections between job-specific stressors and important characteristics of the occupation being studied. These connections were consistent with previous research and suggest that before attempting to identify job-specific stressors, researchers need to first become familiar with the nature and context of the occupation. The final issue addressed in this thesis was the role of work and non-work support. The findings indicate that the support provided by supervisors and colleagues was a significant predictor of wellbeing for both managers and professional footballers. In contrast, the level of explained strain accounted for by non-work support was not significant. These results indicate that when developing strategies to protect and enhance employee well-being, particular attention should be given to monitoring and, where necessary, boosting the effectiveness of work-based support. The findings from this thesis have been fed back to the management and sporting communities via conference presentations and peer-reviewed journals (refer pp 220-221). All three studies have been presented at national and international conferences and, overall, were well received by participants. Similarly, the methods, results and major findings arising from Studies One and Two have been critiqued by anonymous reviewers from two international journals. These papers have been accepted for publication in 2001 and 2002 and feedback from the reviewers indicates that the findings represent a significant and unique contribution to the literature. The results of Study Three are currently under review by a sports psychology journal.

Characterization of the moisture absorption and thermal ageing behaviour of polymeric composite systems using Raman spectroscopy

Advanced polymeric materials and their respective composites are fast becoming one of the world's most frequently used engineering materials. They find application in the manufacture of e.g. boat hulls, high performance motor vehicles, aircraft components and sports goods. Their high specific strength and specific stiffness give them the edge in applications where weight savings are critical, but their long-term durability is often questioned. These materials are susceptible to environmental conditions such as temperature and humidity. There is also a lack of relevant data, due to the long time-scales required for testing. In this study, the Raman technique has been used to monitor the degradation of two composite systems, namely: a rubber toughened vinylester material used in the marine industry and a high temperature bismaleimide/carbon fibre aerospace composite. Preliminary Raman studies show that the toughening rubber particles dispersed in the cured vinylester resin are leached out during hygrothermal ageing. The weight gain during ageing suggests that this leaching process occurs concurrently with the absorption of water molecules. An increase in the degree of cross-linking is observed when bismaleimide/carbon fibre composite is aged at high temperature. This cross- linking tendency decreases with increasing depth within the carbon fibre bundle.

Novel nanocomposite fibres for technical textile applications

Technical textiles, based on advanced polymeric materials, are an important segment of the synthetic textile market. This area has seen considerable growth in recent times, now accounting for almost 25% of all manufactured synthetic fibres, and has driven the recent development of a range of specialist high performance polymer fibres that are stronger, lighter or have improved heat and fire resistance. However, the increasing size of the market has highlighted the need for materials that have improved performance whilst maintaining low manufacturing costs. These factors have resulted in a change in how new specialty fibres are developed and the emphasis in this field is now on the upgrading or improving of the properties of commodity (conventional) fibres by modifying their properties to suit specific applications.

This paper will describe our work on preparing novel polymer nanocomposite fibres by the addition of clay nanoparticles during melt extrusion. The effect of the nanoparticles on the processing of the fibres and the result on the physical morphology and mechanical properties will be described.

An evaluation of the performance of advanced melded composite joints

Melding is an efficient three step composite joining process that involves the selective cure of composite adherends before the final adhesive joint is created using the adherends own resin system. Melding does not require many of the processes and compromises associated with conventional techniques like adhesive bonding and mechanical fastening.

The Taguchi design of experiments technique was used to optimise three melded joint factors for a unidirectional epoxy prepreg material. The performance of the joint was evaluated using tensile and flexural strength as well as flexural modulus. It was found that not having a step for every ply in the joint was the most influential factor affecting joint performance. This was due to the differing failure modes induced by this factors various levels, which varied the amount of fibre breakage at failure.

Structural and material properties of a rapidly cured thermoplastic-toughened epoxy system

Thermoplastic-toughened epoxy resins are widely used as matrices in modern composite prepreg systems. Rapid curing of thermoplastic-toughened epoxy matrix composites results in different mechanical properties. To investigate the structure–property relationship, we investigated a poly(ether sulfone)-modified triglycidylaminophenol/ 4,4'-diamino diphenyl sulfone system that was cured at different heating rates. An intermediate dwell was also applied during the rapid heating of the thermoplasticmodified epoxy system. We found that a higher heating rate led to a larger domain size of the phase-separated macrostructure and also facilitated more complete phase separation. The intermediate dwell helped phase separation to proceed even further, leading to an even larger domain size of the macrostructure. A carbon-fiber-reinforced polymer matrix composite prepreg based on the poly(ether sulfone)-modified multifunctional epoxy system was cured with the same schedule. The rapidly heated composite laminates exhibited higher mode I delamination fracture toughness than the slowly heated material.

Inspection of drop-weight impact damage in woven CFRP laminates fabricated by different processes

The influence of manufacturing process on the drop-weight impact damage in woven carbon/epoxy laminates was inspected by visual observation, dyepenetrant X-ray technique, and optical microscopy observation. The MTM56/ CF0300 woven quasi-isotropic laminates were fabricated by two processes: the autoclave and the Quickstep processes. Quickstep^TM is a novel composite manufacturing process, which was designed for the out-of-autoclave production of high-quality composite parts at lower cost. It utilizes higher heat conduction of fluid other than gas to transfer heat to components, which results in much shorter cure cycles. The laminates cured by this fast heating process showed different impact failure modes from those cured by the conventional autoclave process. The residual indentation in the top side of the Quickstep-cured laminates had a bigger diameter, but a smaller depth at the same impact energy level. Dye-penetrant X-ray revealed more intense and connected impact damage regions in the autoclave-cured laminates. Optical micrography as a supplementary method showed less severe matrix damage in the quickstep-cured laminates indicating a more ductile property of the resin matrix cured at a faster heating rate.

Study on thermoplastic-modified multifunctional epoxies : influence of heating rate on cure behaviour and phase separation

The effect of heating rate on the cure behaviour and phase separation of thermoplastic-modified epoxy systems was investigated. Polyethersulphone (PES) modified multifunctional epoxies, triglycidyl-aminophenol (TGAP) and tetraglycidyldiaminodiphenylmethane (TGDDM), as well T300/914 prepreg were used. It was shown that heating rate had a significant influence on the cure kinetics and phase structures of investigated systems. Greater heating rate causes higher epoxy conversion. The domain size of the macrophases formed from phase separation increases with the increase of heating rate. A more complete phase separation is achieved by fast heated thermoplastic-modified epoxy blends.

Thermal and mechanical properties of a dendritic hydroxyl-functional hyperbranched polymer and tetrafunctional epoxy resin blends

Blends of a tetrafunctional epoxy resin, tetraglycidyl- 4,40'-diaminodiphenylmethane (TGDDM), and a hydroxylfunctionalized hyperbranched polymer (HBP), aliphatic hyperbranched polyester Boltorn H40, were prepared using 3,3'-diaminodiphenyl sulfone (DDS) as curing agent. The phase behavior and morphology of the DDS-cured epoxy/HBP blends with HBP content up to 30 phr were investigated by differential scanning calorimetry (DSC), dynamic mechanical analysis (DMA), and scanning electron microscopy (SEM). The phase behavior and morphology of the DDS-cured epoxy/HBP blends were observed to be dependent on the blend composition. Blends with HBP content from 10 to 30 phr, show a particulate morphology where discrete HBP-rich particles are dispersed in the continuous cured epoxy-rich matrix. The cured blends with 15 and 20 phr exhibit a bimodal particle size distribution whereas the cured blend with 30 phr HBP demonstrates a monomodal particle size distribution. Mechanical measurements show that at a concentration range of 0–30 phr addition, the HBP is able to almost double the fracture toughness of the unmodified TGDDM epoxy resin. FTIR displays the formation of hydrogen bonding between the epoxy network and the HBP modifier.

Strain rate effects on the energy absorption of rapidly manufactured composite tubes

Quasi-static and intermediate rate axial crush tests were conducted on tubular specimens of Carbon/Epoxy (Toray T700/G83C) and Glass/Polypropylene (Twintex). The quasi-static tests were conducted at 10 mm/min (1.67 x 10¯⁴ m/s); five different crush initiators were used. Tests at intermediate rates were performed at speeds of 0.25, 0.5, 0.75, 1, 2, and 4m/s. Modes of failure and specific energy absorption (SEA) values were studied. The highest SEA measured was 86 kJ/kg. This value was observed using Carbon/Epoxy samples at quasi static rates with a 45° chamfer initiator. The highest energy absorption for Twintex tubes was observed to be 57.56 kJ/kg during 45° chamfer initiated tests at 0.25 m/s. Compared with steel and aluminium, SEA values of 15 and 30 kJ/kg, respectively, the benefits of using composite materials in crash structures become apparent.

Nonisothermal Crystallization Behavior of Poly(m-xylene adipamide)/Montmorillonite Nanocomposites

This article reports the nonisothermal crystallization behavior of MXD6 and its clay nanocomposite system (MXD6/MMT) using differential scanning calorimetry (DSC). The DSC experimental data were analyzed by theoretical modeling of the crystallization kinetics using the Avrami, Ozawa, Jeziorny, and the combined Avrami―Ozawa semiempirical models. It has been determined that these models adequately described the crystallization behavior of the MXD6 nanocomposite at cooling rates below 20 °C/min, but there was a deviation from linear dependence at higher cooling rates. This was attributed to changes of both the free energy and the cooling crystallization function K(T) over the entire crystallization process, as well as possible relaxation effects leading to structural rearrangements. In addition, the activation energy determined using the differential isoconversional method of Friedman was also found to vary, indicating changes in both the free energy and crystallization mechanism. Despite the lack of a reliable theoretical model, the heterogeneous nucleating activity of the MMT nanoparticles was demonstrated and quantified using Dobreva's method (Φ = 0.71), and the crystallization rate for the nanocomposite system was found to be greater than pure MXD6 by up to 79% at 40 °C/min.