title: Sub-optimal choice in the Brushtail possum (Trichosurus vulpecula): The effect of terminal link duration on choice

authors: Bremner, Stephanie J

subjects: Sub-optimal

abstract: Sub-optimal choice procedures are commonly used to investigate an animal model of human gambling, and the numerous variables which can affect choice responding (Zentall, 2011). This procedure typically presents two alternatives, one which provides less overall reinforcement than the other. This study aimed to examine whether manipulating terminal link duration on both alternatives would have an effect on possums level of preference towards either alternative, and whether possums would attend to overall reinforcement probability, or discriminative stimuli. Overall, subjects responded optimally at all terminal link durations, regardless of position of the optimal alternative. Response latencies towards the non-preferred alternative were longer than those towards the preferred alternative. Response rates towards both stimuli on the discriminative alternative were similar, indicating that possums were not discriminating between these stimuli. This suggests that terminal link duration does not affect preference when it is altered on both alternatives. The results of this study along with other research in this area suggests that the variables that appear to have the strongest influence on sub-optimal choice are impulsivity and reinforcer deprivation levels, or motivating operations.

text: Sub-optimal choice in the Brushtail possum (Trichosurus vulpecula): The effect of terminal link duration on choice Sub-optimal choice procedures are commonly used to investigate an animal model of human gambling, and the numerous variables which can affect choice responding (Zentall, 2011). This procedure typically presents two alternatives, one which provides less overall reinforcement than the other. This study aimed to examine whether manipulating terminal link duration on both alternatives would have an effect on possums level of preference towards either alternative, and whether possums would attend to overall reinforcement probability, or discriminative stimuli. Overall, subjects responded optimally at all terminal link durations, regardless of position of the optimal alternative. Response latencies towards the non-preferred alternative were longer than those towards the preferred alternative. Response rates towards both stimuli on the discriminative alternative were similar, indicating that possums were not discriminating between these stimuli. This suggests that terminal link duration does not affect preference when it is altered on both alternatives. The results of this study along with other research in this area suggests that the variables that appear to have the strongest influence on sub-optimal choice are impulsivity and reinforcer deprivation levels, or motivating operations.

year: 2016

title: Characterizing the mechanical properties of fused deposition modelling natural fiber recycled polypropylene composites

authors: Milosevic, M.

abstract: The objective of this investigation was to characterize the performance of natural fiber reinforced polypropylene composites in fused deposition modelling (FDM). Composite filaments comprising of pre-consumer recycled polypropylene with varying contents of hemp or harakeke fibers were extruded from which tensile test specimens were made using FDM. Filament and test specimens were tensile tested and properties were compared with plain polypropylene samples; the ultimate tensile strength and Young’s modulus of reinforced filament increased by more than 50% and 143%, respectively, for both 30 wt % hemp or harakeke compared to polypropylene filament. However, the same degree of improvement was not seen with the FDM test specimens, with several compositions having properties lower than for unfilled polypropylene. SEM analysis of fracture surfaces revealed uniform fiber dispersion and reasonable fiber alignment, but porosity and fiber pull-out were also observed. Fiber reinforcement was found to give benefit regarding dimensional stability during extrusion and FDM, which is of major importance for its implementation in FDM. Recommendations for optimization of processing in order to enhance build quality and improve mechanical properties are provided.

text: Characterizing the mechanical properties of fused deposition modelling natural fiber recycled polypropylene composites The objective of this investigation was to characterize the performance of natural fiber reinforced polypropylene composites in fused deposition modelling (FDM). Composite filaments comprising of pre-consumer recycled polypropylene with varying contents of hemp or harakeke fibers were extruded from which tensile test specimens were made using FDM. Filament and test specimens were tensile tested and properties were compared with plain polypropylene samples; the ultimate tensile strength and Young’s modulus of reinforced filament increased by more than 50% and 143%, respectively, for both 30 wt % hemp or harakeke compared to polypropylene filament. However, the same degree of improvement was not seen with the FDM test specimens, with several compositions having properties lower than for unfilled polypropylene. SEM analysis of fracture surfaces revealed uniform fiber dispersion and reasonable fiber alignment, but porosity and fiber pull-out were also observed. Fiber reinforcement was found to give benefit regarding dimensional stability during extrusion and FDM, which is of major importance for its implementation in FDM. Recommendations for optimization of processing in order to enhance build quality and improve mechanical properties are provided.

year: 2017

title: Beyond structuralism: Exploring a semantic based approach for describing the Māori language in grammar books and textbooks for pedagogical purposes

authors: Taiapa, Michael William

subjects: Māori

abstract: Since the 1950s, the advancements and developments in English language studies has had a profound impact on its description that has made it less syntactically driven and more communicatively oriented. This has the potential to influence language description moving it from a purely structurally focused orientation to a more semantically focused one that could influence pedagogic outcomes in more meaningful and useful ways. Nevertheless, in the case of the Māori language, its description has largely focused on structure linguistics that was prevalent in the 19th and early 20th centuries. There has been very little focus on a semantic description and this, in turn, is reflected in grammar books and textbooks on te reo. This thesis set out to explore a semantic approach to describe te reo and to rethink how this type of description may be realized and included in the design of grammar books and textbooks for the teaching and learning of te reo in the broader field of second language pedagogy and acquisition. The thesis also includes a practical component in which a small sample of Māori language teachers were interviewed to determine how linguistic and/ or semantic approaches to describe te reo may have or have impacted on their own beliefs, attitudes, and teaching practices (See, Chapter 7). Thus, it is argued here that research-based studies, advancements, and developments in language descriptions over the past five decades (See, for example, Council of Europe, 1949; Fillmore, 1967; Longacre, 1968; & Crombie, 1985b) should play central roles in the design of a semantic based description of the Māori language from which a linguistic based description can significantly benefit.

text: Beyond structuralism: Exploring a semantic based approach for describing the Māori language in grammar books and textbooks for pedagogical purposes Since the 1950s, the advancements and developments in English language studies has had a profound impact on its description that has made it less syntactically driven and more communicatively oriented. This has the potential to influence language description moving it from a purely structurally focused orientation to a more semantically focused one that could influence pedagogic outcomes in more meaningful and useful ways. Nevertheless, in the case of the Māori language, its description has largely focused on structure linguistics that was prevalent in the 19th and early 20th centuries. There has been very little focus on a semantic description and this, in turn, is reflected in grammar books and textbooks on te reo. This thesis set out to explore a semantic approach to describe te reo and to rethink how this type of description may be realized and included in the design of grammar books and textbooks for the teaching and learning of te reo in the broader field of second language pedagogy and acquisition. The thesis also includes a practical component in which a small sample of Māori language teachers were interviewed to determine how linguistic and/ or semantic approaches to describe te reo may have or have impacted on their own beliefs, attitudes, and teaching practices (See, Chapter 7). Thus, it is argued here that research-based studies, advancements, and developments in language descriptions over the past five decades (See, for example, Council of Europe, 1949; Fillmore, 1967; Longacre, 1968; & Crombie, 1985b) should play central roles in the design of a semantic based description of the Māori language from which a linguistic based description can significantly benefit.

year: 2023