title: The time machine: Norman Taylor Memorial Lecture 2002

authors: Lowe, David J.

subjects: tephra

abstract: I’ve chosen to talk about five topics dealing with long-standing pedological or paleoenvironmental problems involving tephrostratigraphy. I’ll begin with the oldest tephras and work ‘stratigraphically upwards’ to the youngest. Along the way I’ll mention or show a few of the people I’ve worked with, or who were involved historically in the research areas. The second part of the talk will begin when we reach the year 1952. Among a range of personal observations relating to the birth of the society and to Norman Taylor, I will attempt to explain how I came to be giving this lecture today.

text: The time machine: Norman Taylor Memorial Lecture 2002 I’ve chosen to talk about five topics dealing with long-standing pedological or paleoenvironmental problems involving tephrostratigraphy. I’ll begin with the oldest tephras and work ‘stratigraphically upwards’ to the youngest. Along the way I’ll mention or show a few of the people I’ve worked with, or who were involved historically in the research areas. The second part of the talk will begin when we reach the year 1952. Among a range of personal observations relating to the birth of the society and to Norman Taylor, I will attempt to explain how I came to be giving this lecture today.

year: 2002

title: Evidence for a third thermal parameter of enzymes

authors: Peterson, Michelle E.

abstract: This thesis describes tests of a new hypothesis describing the effect of temperature on enzyme activity. 
Traditionally, the dependence of enzyme activity on temperature has been described by a model (the 'Classical Model') consisting of two processes: the catalytic reaction defined by  ΔG‡cat, and irreversible inactivation defined by ΔG‡inact. 
To account for the anomalies found in the variation of enzyme activity with temperature, a new model (the 'Equilibrium Model') has been formulated to describe the effect of temperature on enzyme activity. 
In addition to the processes described by ΔG‡cat and ΔG‡inact, this model incorporates an inactive (but not denatured) form of the enzyme (Einact) that is in reversible equilibrium with the active form (Eact). The equilibrium between Eact and Einact is described by an equilibrium constant (Keq), whose temperature dependence is characterised in terms of the enthalpy of the equilibrium, ΔHeq, and a new thermal parameter, Teq, which is the temperature at which the concentrations of Eact and Einact are equal. 
This research has set out to: test the 'Equilibrium Model'; investigate the molecular basis of the temperature-dependent interconversion of the active and inactive forms of the enzyme; develop methods for the reliable determination of Teq, and outline the assay parameters required for accurate determination of Teq; examine the biotechnological implications of Teq; and finally, examine the evolutionary and ecological implications of Teq 
The 'Equilibrium Model' was tested by comparing 3D plots of experimental data (expressed as rate versus temperature versus time) collected for five enzymes with the 3D plots of the outputs predicted by the 'Classical' and 'Equilibrium' models. This analysis found that all five enzymes behaved as predicted by the 'Equilibrium Model', in displaying clear temperature optima at time zero, and led to the determination of plausible values for ΔG‡cat, ΔG‡inact, ΔHeq, and Teq. 
The value of Teq was affected when the enzyme-substrate interaction was altered (by the use of different substrates) but was, in general, unaffected by the addition of denaturing or stabilising agents to the assay. These results give some insight into the molecular basis of the equilibrium and, together with the fast timescale with which the Eact/Einact equilibrium occurs, support the hypothesis that it is unlikely that Einact is significantly unfolded and that the transition from Eact to Einact involves only a local (reversible) conformational change, possibly near or at the active site; in contrast to the slower and largely irreversible (under assay conditions) global conformational changes associated with thermal denaturation. 
The methodology for the determination of Teq was developed and extended to allow less laborious determination of Teq and to allow the determination of Teq using assay systems that are less than "ideal". Minimum assay parameters were determined in terms of sampling rate and temperature range. 
The potential implications of Teq for enzyme evolution, protein engineering and enzyme reactor performance have been introduced and discussed. 
The characterisation of three enzymes, once each from a psychrophilic, mesophilic and thermophilic source, has given some indication of the ecological and environmental implications of Teq, and suggests that Teq is a better indication of the source temperature of the enzyme than thermal stability and that ΔHeq  reflects the thermal environment from which the enzyme was sourced. 
The results of this research are such that Teq can now be considered a fundamental thermal parameter of enzymes and is required alongside the Arrhenius activation energy and thermal stability to completely account for the way in which enzyme activity behaves with respect to temperature.

text: Evidence for a third thermal parameter of enzymes This thesis describes tests of a new hypothesis describing the effect of temperature on enzyme activity. 
Traditionally, the dependence of enzyme activity on temperature has been described by a model (the 'Classical Model') consisting of two processes: the catalytic reaction defined by  ΔG‡cat, and irreversible inactivation defined by ΔG‡inact. 
To account for the anomalies found in the variation of enzyme activity with temperature, a new model (the 'Equilibrium Model') has been formulated to describe the effect of temperature on enzyme activity. 
In addition to the processes described by ΔG‡cat and ΔG‡inact, this model incorporates an inactive (but not denatured) form of the enzyme (Einact) that is in reversible equilibrium with the active form (Eact). The equilibrium between Eact and Einact is described by an equilibrium constant (Keq), whose temperature dependence is characterised in terms of the enthalpy of the equilibrium, ΔHeq, and a new thermal parameter, Teq, which is the temperature at which the concentrations of Eact and Einact are equal. 
This research has set out to: test the 'Equilibrium Model'; investigate the molecular basis of the temperature-dependent interconversion of the active and inactive forms of the enzyme; develop methods for the reliable determination of Teq, and outline the assay parameters required for accurate determination of Teq; examine the biotechnological implications of Teq; and finally, examine the evolutionary and ecological implications of Teq 
The 'Equilibrium Model' was tested by comparing 3D plots of experimental data (expressed as rate versus temperature versus time) collected for five enzymes with the 3D plots of the outputs predicted by the 'Classical' and 'Equilibrium' models. This analysis found that all five enzymes behaved as predicted by the 'Equilibrium Model', in displaying clear temperature optima at time zero, and led to the determination of plausible values for ΔG‡cat, ΔG‡inact, ΔHeq, and Teq. 
The value of Teq was affected when the enzyme-substrate interaction was altered (by the use of different substrates) but was, in general, unaffected by the addition of denaturing or stabilising agents to the assay. These results give some insight into the molecular basis of the equilibrium and, together with the fast timescale with which the Eact/Einact equilibrium occurs, support the hypothesis that it is unlikely that Einact is significantly unfolded and that the transition from Eact to Einact involves only a local (reversible) conformational change, possibly near or at the active site; in contrast to the slower and largely irreversible (under assay conditions) global conformational changes associated with thermal denaturation. 
The methodology for the determination of Teq was developed and extended to allow less laborious determination of Teq and to allow the determination of Teq using assay systems that are less than "ideal". Minimum assay parameters were determined in terms of sampling rate and temperature range. 
The potential implications of Teq for enzyme evolution, protein engineering and enzyme reactor performance have been introduced and discussed. 
The characterisation of three enzymes, once each from a psychrophilic, mesophilic and thermophilic source, has given some indication of the ecological and environmental implications of Teq, and suggests that Teq is a better indication of the source temperature of the enzyme than thermal stability and that ΔHeq  reflects the thermal environment from which the enzyme was sourced. 
The results of this research are such that Teq can now be considered a fundamental thermal parameter of enzymes and is required alongside the Arrhenius activation energy and thermal stability to completely account for the way in which enzyme activity behaves with respect to temperature.

year: 2005

title: The Debate over 'Kai Tangata' (Maori Cannibalism): New Perspectives from the Correspondence of the Marists

authors: Jennings, William

subjects: cannibalism

abstract: French Marist missionaries working in New Zealand from 1838 sometimes mentioned Maori cannibalism in their correspondence. This article finds that the Marists considered cannibalism to be a cultural practice of minor interest, not a defining point of difference between Maori and Europeans. The article also finds some evidence of ritual cannibalism, but not of mass battlefield cannibalism or of the eating of people for food.

text: The Debate over 'Kai Tangata' (Maori Cannibalism): New Perspectives from the Correspondence of the Marists French Marist missionaries working in New Zealand from 1838 sometimes mentioned Maori cannibalism in their correspondence. This article finds that the Marists considered cannibalism to be a cultural practice of minor interest, not a defining point of difference between Maori and Europeans. The article also finds some evidence of ritual cannibalism, but not of mass battlefield cannibalism or of the eating of people for food.

year: 2011