title: Testing Macromolecular Rate Theory

authors: Kraakman, Kirsty Leigh

subjects: enzymes

abstract: Enzymatic rate increase with respect to temperature has widely been described by transition-state theory. The experimentally observed rate decline above an optimum temperature (Tₒₚₜ) for enzymes has previously been attributed to thermal denaturation, despite the known discrepancies with this rationalisation. Recently, a new model has been proposed to describe the temperature dependence of enzymatic rates: macromolecular rate theory (MMRT). This new theory incorporates heat capacity into the rate equation to provide a more robust thermodynamic description of rates, and account for the distinct curvature seen in biological temperature-rate profiles. The current study explores the effect of enzyme vibrational modes on heat capacity, and how alterations to the distribution of these modes, by heavy isotope substitution, affect the change in heat capacity along the reaction coordinate. The results presented show clear evidence for the role of vibrational mode frequency distributions in governing the curvature of temperature-rate profiles, and present a hypothesis for how this shift differs for the enzyme-substrate complex and the enzyme-transition state complex. The study also addresses the ability of MMRT to accurately model enzymatic rates over a wide temperature range for two different enzymes. As a result of this study, a new MMRT equation was generated to include a temperature dependence term for the heat capacity, a factor previously considered negligible. The data generated has shown that heat capacity is temperature dependent and this is a significant factor in accurately describing enzymatic rates with respect to temperature. In particular, for complex enzymatic reactions whose enthalpy distribution is significantly narrowed over the reaction co-ordinate. These findings have helped to develop MMRT to provide more accurate descriptions of a broader range of data. Additionally, the conclusions regarding vibrational mode distribution provide insight into the physical basis for heat capacity changes over the course of the enzymatic reaction. Investigation of the hypotheses generated from this research will offer further insight into the mechanistic contributions of vibrational modes and heat capacity in enzyme catalysis.

text: Testing Macromolecular Rate Theory Enzymatic rate increase with respect to temperature has widely been described by transition-state theory. The experimentally observed rate decline above an optimum temperature (Tₒₚₜ) for enzymes has previously been attributed to thermal denaturation, despite the known discrepancies with this rationalisation. Recently, a new model has been proposed to describe the temperature dependence of enzymatic rates: macromolecular rate theory (MMRT). This new theory incorporates heat capacity into the rate equation to provide a more robust thermodynamic description of rates, and account for the distinct curvature seen in biological temperature-rate profiles. The current study explores the effect of enzyme vibrational modes on heat capacity, and how alterations to the distribution of these modes, by heavy isotope substitution, affect the change in heat capacity along the reaction coordinate. The results presented show clear evidence for the role of vibrational mode frequency distributions in governing the curvature of temperature-rate profiles, and present a hypothesis for how this shift differs for the enzyme-substrate complex and the enzyme-transition state complex. The study also addresses the ability of MMRT to accurately model enzymatic rates over a wide temperature range for two different enzymes. As a result of this study, a new MMRT equation was generated to include a temperature dependence term for the heat capacity, a factor previously considered negligible. The data generated has shown that heat capacity is temperature dependent and this is a significant factor in accurately describing enzymatic rates with respect to temperature. In particular, for complex enzymatic reactions whose enthalpy distribution is significantly narrowed over the reaction co-ordinate. These findings have helped to develop MMRT to provide more accurate descriptions of a broader range of data. Additionally, the conclusions regarding vibrational mode distribution provide insight into the physical basis for heat capacity changes over the course of the enzymatic reaction. Investigation of the hypotheses generated from this research will offer further insight into the mechanistic contributions of vibrational modes and heat capacity in enzyme catalysis.

year: 2017

title: Enhancing athletic performance: Can video modelling and feedback on forehand hitting increase passing accuracy of field hockey players?

authors: Platt, Dylan

abstract: Research in applied behaviour analysis and sports performance is becoming more evident in sporting environments. I aimed to explore the effectiveness of video modelling (VM), and video modelling combined with feedback (VF), and whether combined video modelling and video feedback (VM+VF) is an effective coaching tool to teach and improve athletes’ skill accuracy. A single subject multiple baseline design across participants was used. Four male field hockey players, who were all members of the same North Island National U18 team, took part in this study. The intervention had three phases: beginner-level video modelling; intermediate level video modelling; intermediate video modelling + video feedback. Participants watched a short instructional video and then practiced their forehand hitting in a structured practice session which was videotaped. Both video modelling conditions were effective, but the most performance gains were seen in Phase 3 where video feedback was added. All the participants showed an increase in the number of successful forehand hits after being exposed to VM and VM+VF, supporting the effectiveness of the intervention. These findings add to the existing body of work that supports the use of applied behaviour analysis techniques in sports training. Video modelling and video feedback may be useful for enhancing skill execution in field hockey. Further research should be conducted to determine the long-term retention of these skills and the usability of similar interventions for other technical aspects of field hockey and other sports.

text: Enhancing athletic performance: Can video modelling and feedback on forehand hitting increase passing accuracy of field hockey players? Research in applied behaviour analysis and sports performance is becoming more evident in sporting environments. I aimed to explore the effectiveness of video modelling (VM), and video modelling combined with feedback (VF), and whether combined video modelling and video feedback (VM+VF) is an effective coaching tool to teach and improve athletes’ skill accuracy. A single subject multiple baseline design across participants was used. Four male field hockey players, who were all members of the same North Island National U18 team, took part in this study. The intervention had three phases: beginner-level video modelling; intermediate level video modelling; intermediate video modelling + video feedback. Participants watched a short instructional video and then practiced their forehand hitting in a structured practice session which was videotaped. Both video modelling conditions were effective, but the most performance gains were seen in Phase 3 where video feedback was added. All the participants showed an increase in the number of successful forehand hits after being exposed to VM and VM+VF, supporting the effectiveness of the intervention. These findings add to the existing body of work that supports the use of applied behaviour analysis techniques in sports training. Video modelling and video feedback may be useful for enhancing skill execution in field hockey. Further research should be conducted to determine the long-term retention of these skills and the usability of similar interventions for other technical aspects of field hockey and other sports.

year: 2025

title: 'Freedom’s Ramparts on The Sea': The postcolonial New Zealand landscape and the quest for sustainability

authors: Morad, Munir

subjects: postcolonialism

abstract: New Zealand’s colonial legacy has had a major impact on the shape of its landscape. The European settlement of New Zealand transformed both the land itself as well as the tenure arrangements that had hitherto followed traditional Maori practices. The increasing political influence of the modem conservation movement in New Zealand has been mirrored by a parallel rise in Maori engagement with environmental issues. Land tenure claims brought by the Maori under the 1970’s Treaty of Waitangi Act have enabled an alliance of Maori and environmental interests to be forged. This linkage however is very recent, and if the current unsustainable land use practices are to be mitigated in New Zealand, a synthesis of the essential elements in both cultural traditions is necessary.
Culture shapes how people identify and evaluate elements of their environment, and influences their behaviour and experiences. At a more pragmatic level, culture provides the social infrastructure and institutions that determine how renewable land resources are used and managed. The authors highlight the links between postcolonial culture and landscape management in New Zealand, contrasting Pakeha-Maori points of view and attempting to mediate between these conflicting positions. These links are examined in the context of new social, economic and ecological forces that are shaping the country’s postcolonial landscape.

text: 'Freedom’s Ramparts on The Sea': The postcolonial New Zealand landscape and the quest for sustainability New Zealand’s colonial legacy has had a major impact on the shape of its landscape. The European settlement of New Zealand transformed both the land itself as well as the tenure arrangements that had hitherto followed traditional Maori practices. The increasing political influence of the modem conservation movement in New Zealand has been mirrored by a parallel rise in Maori engagement with environmental issues. Land tenure claims brought by the Maori under the 1970’s Treaty of Waitangi Act have enabled an alliance of Maori and environmental interests to be forged. This linkage however is very recent, and if the current unsustainable land use practices are to be mitigated in New Zealand, a synthesis of the essential elements in both cultural traditions is necessary.
Culture shapes how people identify and evaluate elements of their environment, and influences their behaviour and experiences. At a more pragmatic level, culture provides the social infrastructure and institutions that determine how renewable land resources are used and managed. The authors highlight the links between postcolonial culture and landscape management in New Zealand, contrasting Pakeha-Maori points of view and attempting to mediate between these conflicting positions. These links are examined in the context of new social, economic and ecological forces that are shaping the country’s postcolonial landscape.

year: 2003